Events

Details: Zoom link to join: https://weizmann.zoom.us/j/98861083979?pwd=Q1FmbDBYNHR2QnN ... Read more

Abstract: Hippocampal place cells fire in a spatially selective manner and are thought to ... Read more Hippocampal place cells fire in a spatially selective manner and are thought to support the formation of a cognitive-map that allows the association of an event to its spatial context. It has long been thought that within familiar spatial contexts, such cognitive maps should be stable over time, and that individual place cells should retain their firing properties. However, recent findings have demonstrated that hippocampal spatial codes gradually change over timescales of minutes to weeks. These finding raised several fundamental questions: What are the contributions of the passage of the time and the amount of experience to the observed drift in hippocampal ensemble activity? To what extent are different aspect of place code stability affected by time and experience? To address these questions, I conducted a series of Ca2+ imaging experiments in which mice repeatedly explored familiar environments. Different environments were visited at different intervals, which allowed distinguishing between the contribution of time and experience to code stability. I found that time and experience differentially affected distinct aspects of hippocampal place codes: changes in activity rates were mostly affected by time, whereas changes in spatial tuning was mostly affected by experience. These findings suggest that different biological mechanisms underlie different aspects of representational drift in the hippocampus. These findings add to the growing body of research suggesting that representational drift is an inherent property of neural networks in vivo, and point to the different candidate mechanisms that could underlie this drift. https://weizmann.zoom.us/j/98861083979?pwd=Q1FmbDBYNHR2QnNKSUNpeHlLdm94dz09 Meeting ID: 988 6108 3979 Password: 682422

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Special seminar with Dr. Yaara Oren

Date:

16

Monday

August

2021

Lecture / Seminar

Time: 15:00-16:00

Title: Beyond Darwin: understanding cancer persister cells

Lecturer: Dr. Yaara Oren

Organizer: Department of Molecular Genetics

Contact: sandra.britton@weizmann.ac.il

Details: zoom: https://weizmann.zoom.us/j/96160519106?pwd=ZSs0NXd0WWZSaTBQTTRxSkZ5dmRvdz09

Abstract: Despite favorable initial response to therapy, a third of cancer patients will d ... Read more Despite favorable initial response to therapy, a third of cancer patients will develop recurrent disease and succumb to it within five years of diagnosis. While there has been much progress in characterizing the pathways that contribute to stable genetic drug resistance, the mechanisms underlying early reversible resistance, also known as persisters-driven resistance, remain largely unknown. It has long been believed that persisters represent a subset of cells that happen to be non-proliferating at the time of treatment, and therefore can survive drugs that preferentially kill rapidly proliferating cells. However, in my talk I will describe a rare persister population which, despite not harboring any resistance-conferring mutation, can maintain proliferative capacity in the presence of drug. To study this rare, transiently-resistant, cycling persister population, we developed Watermelon, a high-complexity expressed barcode lentiviral library for simultaneous tracing of each cell’s clonal origin and proliferative and transcriptional states. We combine single cell transcriptomics with imaging and metabolomics to show that cycling and non-cycling persisters arise from different cell lineages with distinct transcriptional and metabolic programs. Finally, I will describe how by studying persister cells we can gain critical insights on cellular memory, fate, and evolution, which can guide the development of better anti-cancer treatments.

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Principles of functional circuit connectivity: Insights from the zebrafish optic tectum

Date:

04

Wednesday

August

2021

Lecture / Seminar

Time: 10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. German Sumbre

Organizer: Department of Brain Sciences

Details: Host: Dr. Takashi Kawashima takashi.kawashima@weizmann.ac.il tel: 2995

Abstract: Spontaneous neuronal activity in sensory brain regions is spatiotemporally struc ... Read more Spontaneous neuronal activity in sensory brain regions is spatiotemporally structured, suggesting that this ongoing activity may have a functional role. Nevertheless, the neuronal interactions underlying these spontaneous activity patterns, and their biological relevance, remain elusive. We addressed these questions using two-photon and light-sheet Ca2+ imaging of intact zebrafish larvae to monitor the fine structure of the spontaneous activity in the zebrafish optic tectum (the fish's main visual center. We observed that the spontaneous activity was organized in topographically compact assemblies, grouping functionally similar neurons rather than merely neighboring ones, reflecting the tectal retinotopic map. Assemblies represent all-or-none-like sub-networks shaped by competitive dynamics, mechanisms advantageous for visual detection in noisy natural environments. Furthermore, the spontaneous activity structure also emerged in “naive” tecta (tecta of enucleated larvae before the retina connected to the tectum). We thus suggest that the formation of the tectal network circuitry is genetically prone for its functional role. This capability is an advantageous developmental strategy for the prompt execution of vital behaviors, such as escaping predators or catching prey, without requiring prior visual experience. Mutant zebrafish larvae for the mecp2 gene display an abnormal spontaneous tectal activity, thus representing an ideal control to shed light on the biological relevance of the tectal functional connectivity. We found that the tectal assemblies limit the span of the visual responses, probably improving visual spatial resolution.

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Love the neighbor – Unraveling the tumor microenvironment using multiplexed imaging

Date:

08

Thursday

July

2021

Lecture / Seminar

Time: 14:00-15:00

Location: Max and Lillian Candiotty Building

Lecturer: Dr. Leeat Keren

Organizer: Dwek Institute for Cancer Therapy Research

Contact: michal.av@weizmann.ac.il

Details: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09

Yes I Can ! Neural indicators of self-views and their motivational value

Date:

22

Tuesday

June

2021

Lecture / Seminar

Time: 12:30

Lecturer: Prof. Talma Hendler

Organizer: Department of Brain Sciences

Details: Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more

Abstract: Positive view of oneself is central for social motivation and emotional well-b ... Read more Positive view of oneself is central for social motivation and emotional well-being. Such views largely depend on the known positive-bias of social feedbacks, as well as on the value one gives to social attributes such as power or affiliation. Diminished positive self views are a common denominator in depression and social anxiety, suggesting a transdiagnostic biomarkers, yet its neural mechanism is unclear. My talk will describe a series of studies using multiscale imaging and behavioral accounts and their modeling to address the interaction between self related cognition, motivation and learning from experience. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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The interaction of valence and information gain during learning, perception and decision-making

Date:

27

Thursday

May

2021

Lecture / Seminar

Time: 11:00-12:30

Lecturer: Ido Toren (PhD Thesis Defense)

Organizer: Department of Brain Sciences

Details: Neurobiology Students & Postdocs Seminar Zoom link to join: https://weizmann. ... Read more

Abstract: Decision making is a fundamental ability to human life. Even the simplest decisi ... Read more Decision making is a fundamental ability to human life. Even the simplest decision we make requires integration of multiple factors in our brain, such as prior knowledge, information from the environment, emotions and many more. Despite many years of research and numerous important and ground-breaking findings on how learning and decision-making are generated in our brain, a lot of knowledge is still required for a comprehensive understanding of it. My research initiated from the motivation to understand the unique contribution of valence (rewards and punishments) – when presented as feedback during learning – to perception and decision-making. For that purpose, I studied multiple groups of individuals under different experimental conditions created to elucidate behavioral and neural responses to rewards and punishments. I asked how prediction errors (PE, the difference between expected and received outcomes) bias the perception of time, and how valence and information from feedback, factors that are often indistinguishable, differently guide decision making in a multi-choice environment. Using functional MRI and computational models, I found that positive and negative PEs, known to drive learning, bias the perception of time in opposite directions. Positive PEs induce change in the perceived time so it seems longer compared to a neutral condition (no PE). In contrast, when a negative PE is detected, time is perceived to be shorter. My results identify the Putamen, a structure that receives dopaminergic projections and is involved in time perception, as the brain region that likely drives this bias and underlies the interaction between time perception and prediction-errors. In addition, I demonstrated that knowing the outcome valence in advance can enable an information-based decision making, namely one that is not affected by the valence itself and is driven only by the information available in the environment. Because uncertainty regarding choice increases when more options are available to choose from, a ‘right’ feedback provides more information to the learning process, compared to a ‘wrong’ feedback. This was accompanied by a differential activation in the ACC, PFC and striatum. Importantly, in this context, punishment avoidance is equally rewarding, and indeed I found that choice behavior and the neural networks underlying choice and feedback processing are similar in the two scenarios – for punishments and rewards. Overall, my work develops and suggests computational and neural mechanisms for specific roles of the information carried by prediction-errors. These findings can enhance our understanding of the fundamental roles of valence and information gain during learning and decision making. Zoom link to join: https://weizmann.zoom.us/j/92234357805?pwd=aVkrR21CSUVtVS9tSEJYRDkwOFRidz09 Meeting ID: 922 3435 7805 Password: 648092

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Technologies for all-optical interrogation of neural circuits in behaving animalsTechnologies for all-optical interrogation of neural circuits in behaving animals

Date:

25

Tuesday

May

2021

Lecture / Seminar

Time: 12:30

Lecturer: Dr. Adam Packer

Organizer: Department of Brain Sciences

Details: Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more

Abstract: Neural circuits display complex spatiotemporal patterns of activity on the milli ... Read more Neural circuits display complex spatiotemporal patterns of activity on the millisecond timescale during behavior. Understanding how these activity patterns drive behavior is a fundamental problem in neuroscience, and remains a major challenge due to the complexity of their spatiotemporal dynamics. The ability to manipulate activity in genetically defined sets of neurons on the millisecond timescale using optogenetics has provided a powerful new tool for making causal links between neuronal activity and behavior. I will discuss novel approaches that combine simultaneous two-photon calcium imaging and two-photon targeted optogenetic photostimulation with the use of a spatial light modulator (SLM) to provide ‘all-optical’ readout and manipulation of the same neurons in vivo. This approach enables reading and writing of activity in neural circuits with single-cell resolution and single action potential precision during behavior. I will describe the power, limitations and future potential of this approach; and discuss how it can be used to address many important problems in neuroscience, including transforming our search for the neural code and the links between neural circuit activity and behavior. Zoom link to join- https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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Heat Shock Factor 1-dependent extracellular matrix remodeling mediates the transition from chronic intestinal inflammation to colon cancer

Date:

27

Tuesday

April

2021

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Oshrat Galibov-Levi

Organizer: Department of Biomolecular Sciences

Abstract: In the colon, long-term exposure to chronic inflammation drives colitis-associat ... Read more In the colon, long-term exposure to chronic inflammation drives colitis-associated colon cancer (CAC). However, molecular understanding of how this occurs is still lacking. Within the tumor, cancer cells are surrounded by a variety of non-malignant cells and by the extracellular matrix (ECM), which together compose the tumor microenvironment (TME), which is essential for tumor homeostasis and progression. While the cancer cells are highly mutated, the stromal cells are genomically stable. Master regulator heat shock factor 1 (HSF1) was shown to play an important part in the transcriptional reprogramming of the TME. By using proteomic and advanced methods of microscopy and image analysis we show that HSF1-dependent ECM remodeling plays a crucial role in mediating inflammation-driven colon cancer. /j/95881429481?pwd=VkxwUmg1Z2ErZmhpZDJqMTZwellGZz09

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Atmospheric Dynamics on Jupiter: New Results from the Juno Mission

Date:

22

Thursday

April

2021

Colloquium

Time: 11:15-12:30

Location: https://weizmann.zoom.us/j/94477142638?pwd=aWNlZGVzNmdJdnJVZVNZUi9sZ0VBZz09

Lecturer: Yohai Kaspi

Organizer: Faculty of Physics

Abstract: NASA's Juno Mission is now completing its 5 year nominal mission around Jupiter, ... Read more NASA's Juno Mission is now completing its 5 year nominal mission around Jupiter, orbiting the planet in an eccentric polar-orbit every 53 days. One of the prime mission objectives is better understanding the atmospheric dynamics through gravitational, microwave, infrared and magnetic measurements. In this talk, we will focus on three new results explaining different aspects of the dynamics on Jupiter. First, infrared imaging data revealed that Jupiter’s poles are surrounded by 5 cyclones around the North Pole and 8 cyclones around the South Pole. We explain the location, size and stability of these circumpolar cyclones based on vorticity dynamics. Second, using microwave data, revealing Jupiter’s deep ammonia abundance structure, we show that Jupiter has 8 meridional circulation cells in each hemisphere. These cells resemble in their governing physics Earth's midlatitude Ferrel cells, and relate to the observed red and white belts and zones at Jupiter’s cloud-level. Finally, using Juno’s gravity measurements we constrain the depth of Jupiter’s east-west jet-streams, and the depth (mass) of the most iconic vortex in the Solar system — Jupiter’s Great Red Spot. Overall, this unique multiple instrument dataset allows now explaining the governing physics of several outstanding aspects of Jupiter’s internal and atmospheric dynamics. We will also compare the dynamics to those of Saturn, generalizing some of the this new understanding.

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Cellular and circuit basis of distinct memory formation in the hippocampus

Date:

06

Tuesday

April

2021

Lecture / Seminar

Time: 12:30

Lecturer: Dr. Christoph Schmidt-Hieber

Organizer: Department of Brain Sciences

Details: Zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUd ... Read more

Abstract: Formation and retrieval of distinct memories are complementary processes that pu ... Read more Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. zoom link to join-https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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Solving computational problems with coupled lasers

Date:

18

Thursday

March

2021

Colloquium

Time: 11:15-12:30

Location: https://weizmann.zoom.us/j/94477142638?pwd=aWNlZGVzNmdJdnJVZVNZUi9sZ0VBZz09

Lecturer: Nir Davidson

Organizer: Faculty of Physics

Using Ultra-High Field MRI to Study the Human Brain Lecture / Seminar website

Abstract: Computational problems may be solved by realizing physics systems that can simul ... Read more Computational problems may be solved by realizing physics systems that can simulate them. Here we present a new system of coupled lasers in a modified degenerate cavity that is used to solve difficult computational tasks. The degenerate cavity possesses a huge number of degrees of freedom (300,000 modes in our system), that can be coupled and controlled with direct access to both the x-space and k-space components of the lasing mode. Placing constraints on these components are mapped on different computational minimization problems. Due to mode competition, the lasers select the mode with minimal loss to find the solution. We demonstrate this ability for simulating XY spin systems and finding their ground state, for phase retrieval, for imaging through scattering medium, and more.

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Using Ultra-High Field MRI to Study the Human Brain

Date:

04

Thursday

March

2021

Lecture / Seminar

Time: 09:00-10:00

Location: ZOOM

Lecturer: Dr. Edna Furman-Haran and Dr. Tali Weiss

Organizer: Department of Life Sciences Core Facilities

Contact: Edna.Haran@weizmann.ac.il

Gallery: Using Ultra-High Field MRI to Study the Human Brain Gallery

Room Temperature 13C-DNP in Diamond Powder

Date:

18

Thursday

February

2021

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Dr. Daphna Shimon

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Zoom Link: Zoom: https://weizmann.zoom.us/j/91742036303?pwd=cWJuOFBEZUpYU3p6bHBj ... Read more Zoom Link: Zoom: https://weizmann.zoom.us/j/91742036303?pwd=cWJuOFBEZUpYU3p6bHBjUEduRllxdz09 Passcode: 771770 Electron and nuclear spins in diamond have long coherence and relaxation times at room temperature, making them a promising platform for applications such as biomedical and molecular imaging and nanoscale magnetic field sensing. While the optically-active nitrogen-vacancy (NV) defect has received a great deal of attention, the substitutional nitrogen (or P1) center also exhibits long coherence and relaxation times. These P1 centers are typically present at significantly larger concentrations (about an order magnitude larger) than NVs, allowing us to explore the role of P1-P1 interactions in mediating DNP. The system can, in principle, show DNP via the solid effect (SE), cross effect (CE) and Overhauser effect (OE) depending on the P1 concentration and the field. Here, we show enhancement of natural abundance 13C nuclei found within the diamond, using the unpaired electron of the P1 center (concentration 110-130 ppm) in particles with a 15-25 μm diameter, under static conditions at room temperature and 3.4 T. We discuss the DNP spectrum, the active DNP mechanisms and what we can learn about the diamond powder from DNP.

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Crystallization Mechanisms: Classical, Nonclassical, and Beyond

Date:

08

Monday

February

2021

Colloquium

Time: 11:00-12:00

Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09

Lecturer: Prof. Boris Rybtchinski

Organizer: Faculty of Chemistry

Abstract: Understanding how order evolves during crystallization represents a long-standin ... Read more Understanding how order evolves during crystallization represents a long-standing challenge. We will describe our recent studies on crystallization of organic molecules and proteins by cryo-TEM imaging and cryo-STEM tomography. They reveal mechanisms, in which order evolution proceeds via diverse pathways, including various intermediate states. Based on these findings, we suggest a general outlook on molecular crystallization.

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Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization”.

Date:

31

Sunday

January

2021

Lecture / Seminar

Time: 11:00-12:00

Lecturer: Prof. Talila Volk

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWF ... Read more Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWFhZVUVzZz09 The genetic material of live organisms is packed and stored within the nucleus. It contains DNA wrapped around the nucleosomes, which then organized into chromatin fibers that partition into distinct compartments, which eventually fill the entire nucleus. Chromatin three dimensional topology is essential for proper accessibility of transcription factors, which control tissue-specific gene expression programs. Whereas chromatin partition into specific domains has been described in cells in culture conditions, information regarding chromatin 3 dimensional distribution in tissues within live organisms is still missing. We have imaged the chromatin in muscle fibers of live, intact Drosophila larvae, and revealed its 3 dimensional structure. Our results demonstrate novel 3 dimensional architecture of the chromatin which is evolutionary conserved, and has important implications on the regulation of gene expression.

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“Low-field MRI: new perspectives”

Date:

28

Thursday

January

2021

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Prof. Najat Salameh

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Zoom: Link: https://weizmann.zoom.us/j/98957854014?pwd=ZTEyazd6cThxUE90L3ZJbkdkb ... Read more Zoom: Link: https://weizmann.zoom.us/j/98957854014?pwd=ZTEyazd6cThxUE90L3ZJbkdkbkFWQT09 passcode: 159170 Magnetic Resonance Imaging (MRI) is a non-ionizing, non-invasive imaging modality that has become key in modern medicine. Its high value resides in a broad range of soft tissue contrasts or biomarkers that can be tuned to enable the identification and follow-up of many pathophysiological or metabolic processes. Such developments were made possible thanks to almost forty years of hardware and software development, yet access to MRI nowadays remains exclusive, bound to radiology suites in hospitals, and restricted to less than half of the world population. This limited accessibility is mostly due to its one-fits-all design and its prerequisites for intense magnetic field strength that impact cost, siting infrastructure, and clinical compatibility. One way to improve accessibility in MRI is to lower the magnetic field strength that will naturally influence cost, siting, and compatibility. Further, lowering the field strength can translate in smaller footprint designs which geometry and contrast could purposely be tuned to certain targeted applications. Indeed, relaxation mechanisms are known to change with the surrounding magnetic field, with larger T1 dispersion at low field that have for the most part been unexplored. Although very promising, many challenges arise linked to the lower intrinsic nuclear spin polarization inherent to low field technologies, calling for original and innovative approaches to reach clinical relevance. During this seminar, Prof. Najat Salameh will describe those challenges and possible solutions by presenting the current landscape of low field imaging and recent progress made at the Center for Adaptable MRI Technology, Basel University.

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Layers of primary visual cortex as a window into internal models about predicted and simulated environments

Date:

26

Tuesday

January

2021

Lecture / Seminar

Time: 12:30-13:30

Lecturer: Prof. Lars Muckli

Organizer: Department of Brain Sciences

Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more

Abstract: Normal brain function involves the interaction of internal processes with incomi ... Read more Normal brain function involves the interaction of internal processes with incoming sensory stimuli. We have created a series of brain imaging experiments (using 7T fMRI) that sample internal models and feedback mechanisms in early visual cortex. Primary visual cortex (V1) is the entry-stage for cortical processing of visual information. We can show that there are 3 information counter-streams concerned with: (1) retinotopic visual input, (2) top-down predictions of internal models generated by the brain, and (3) top-down imagery acting independently of the perception and prediction loop. Internal models amplify and disamplify incoming information, but there is also mental imagery not interfering with visual perception. Our results speak to the conceptual framework of predictive coding. Healthy brain function will strike a balance between the precision of prediction and prediction update based on prediction error. Our results incorporate state of the art, layer-specific ultra-high field fMRI and other imaging techniques. We argue that fMRI with its capability of measuring dendritic energy consumption is sensitive to activity in different parts of layer spanning neurons, enriching our computational understanding of counter stream brain mechanisms. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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Marine electrical imaging reveals novel freshwater transport mechanism in Hawaiʻi

Date:

26

Tuesday

January

2021

Lecture / Seminar

Time: 11:00

Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09

Lecturer: Eric Attias

Organizer: Department of Earth and Planetary Sciences

Abstract: Conventional hydrogeologic models employed to compute ocean island sustainable y ... Read more Conventional hydrogeologic models employed to compute ocean island sustainable yields and aquifer storage neglect the nearshore and onshore submarine environment’s complexity. However, the onshore aquifer at the island of Hawaiʻi exhibits a significant volumetric discrepancy between high-elevation freshwater recharge and coastal discharge. This study presents a novel transport mechanism of freshwater moving from onshore to onshore via a multilayer formation of water-saturated layered basalts with interbedded low-permeability layers of ash/soil, as revealed by marine-controlled source electromagnetic (CSEM) imaging. We propose that this newly discovered transport mechanism of fresh water may be the governing mechanism in other volcanic islands. Additionally, our water column CSEM imaging detects multiple vertical freshwater plumes extending from the seafloor to the ocean surface. These findings provide valuable information to elucidate hydrogeologic and oceanographic rocesses affecting biogeochemical cycles in coastal waters worldwide.

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New perspectives on interlayer excitons in two-dimensional heterostructures

Date:

19

Tuesday

January

2021

Lecture / Seminar

Time: 18:00-19:00

Lecturer: Dr. Ouri Karni

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCaz ... Read more Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCazNwZz09 Two-dimensional layered (van-der-Waals) heterostructures, made by stacking different monolayers of semiconducting transition-metal dichalcogenides, have been drawing much attention as versatile platforms for studying fundamental solid-state phenomena and for designing opto-electronic devices. Interlayer excitons, electron-hole pairs that bind to each other across the interlayer spacing in these heterostructures, hold promise as key tools for probing the interlayer interface structure, and for exploring many-body interactions(1). With long lifetimes, spin polarization, and electric tunability, interlayer excitons are also promising as flexible information carriers(2, 3). However, they were mostly studied through the scope of their visible light emission, missing essential properties such as their momentum-space image or their absorption strength, necessary for rigorous study of their many-body interactions and potential applications. In this talk I will present our recent studies aimed at measuring such unknown interlayer exciton properties and their dependence on the heterostructure. I will show a new interlayer exciton in WSe2/MoS2 heterostructures which we discovered based on its light emission in infra-red wavelengths, rather than in the visible range(4). I will demonstrate its properties as inferred from its optical interrogation. Then, I will present the quantitative measurement of the elusive optical absorption spectrum of interlayer excitons using electric-field modulation spectroscopy, essential for coherent coupling of light to those excitons(5). Finally, I will reveal how time- and angle-resolved photoemission spectroscopy is used to image the interlayer exciton in momentum-space, yielding its size and binding energy, so far inaccessible through optics(5).

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Vision and Robotics Seminar

Date:

14

Thursday

January

2021

Lecture / Seminar

Time: 12:15-13:30

Title: Next generation localization microscopy - or - how and why to ruin a perfectly good microscope

Lecturer: Yoav Shechtman

Organizer: Faculty of Mathematics and Computer Science,Department of Computer Science and Applied Mathematics,Department of Mathematics

Contact: michal.zer-barak@weizmann.ac.il

Details: In localization microscopy, the positions of individual nanoscale point emitters ... Read more

Abstract: In localization microscopy, the positions of individual nanoscale point emitters ... Read more In localization microscopy, the positions of individual nanoscale point emitters (e.g. fluorescent molecules) are determined at high precision from their point-spread functions (PSFs). This enables highly precise single/multiple-particle-tracking, as well as super-resolution microscopy, namely single molecule localization microscopy (SMLM). To obtain 3D localization, we employ PSF engineering – namely, we physically modify the standard PSF of the microscope, to encode the depth position of the emitter. In this talk I will describe how this method enables unprecedented capabilities in localization microscopy

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‘Identification of Dynamic Components in the Liquid-Liquid Phase Separation of CPEB4 by EPR Spectroscopy’

Date:

14

Thursday

January

2021

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Dr. Manas Seal

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Link: https://weizmann.zoom.us/j/96046369379?pwd=emp0U0wwcmpNQlhsMisrNmp0bjRDdz ... Read more Link: https://weizmann.zoom.us/j/96046369379?pwd=emp0U0wwcmpNQlhsMisrNmp0bjRDdz09 Passcode: 693143 The molecular mechanisms and associated structures and dynamics of liquid-liquid phase separation (LLPS) proteins that form membrane-less organelles in cells have attracted considerable interest in recent years. EPR spectroscopy along with site directed spin labelling (SDSL) using nitroxide spin labels is a well-established technique to study dynamics of proteins. In this seminar I will discuss the dynamic properties of the spin labelled low complexity N-terminal domain of cytoplasmic polyadenylation element binding-4 protein (CPEB4NTD) in its LLPS and non-LLPS states. We found the coexistence of three CPEB4NTD populations with distinct spin label rotational correlation times before and after LLPS. We identified population I as the predominant protein species in the dilute phase, with fast motions that agree with expected dynamic properties of monomeric CPEB4NTD. We assigned population III to a compact ensemble that undergo slow motions, and population II to a looser ensemble experiencing intermediate motions. LLPS, which took place with increasing temperature is associated with increased population of II at the expense of III, while population I remains constant. At the end based on these findings, I will present a three-component equilibrium model that postulates the existence of LLPS-competent CPEB4NTD species (II and III) prior to macroscopic phase separation.

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Diffusion properties of intracellular metabolites: compartment specific probes for cell structure and physiology

Date:

05

Tuesday

January

2021

Lecture / Seminar

Time: 12:30-13:30

Lecturer: Prof. Itamar Ronen

Organizer: Department of Brain Sciences

Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more

Abstract: Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invas ... Read more Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invasive investigations of tissue microstructure, and provides quantitative cytomorphological information on a spatial scale well below the nominal resolution of MRI. The main limitation of DWI is its lack of compartmental specificity, as its “reporter molecule” is water, ubiquitous in all tissue compartments and cell types. Brain metabolites are mostly confined to the intracellular space, and their concentrations vary across cell types. Several metabolites give rise to quantifiable magnetic resonance spectroscopy (MRS) signatures, and are thus considered as compartment-specific and sometimes cell-specific markers. Sensitization of MRS to diffusion results in a set of diffusion properties for a variety of intracellular metabolites, from which microstructural information specific to the intracellular space can be obtained. A proper choice of experimental settings can be used to investigate properties that range from cytoplasmic viscosity and tortuosity of the intracellular space, to overall cell morphological features. The specificity of some metabolites to different cell types such as neurons and astrocytes opens the way to studying morphological properties of different cell populations and monitoring their modulation by physiological changes in health and disease. The presentation will introduce methodological concepts of diffusion-weighted MRS, followed by simple examples that demonstrate the unique ability of diffusion-weighted MRS to characterize cell-type specific structural features. Special emphasis will be bestowed on experimental and modelling frameworks that merge the specificity of diffusion-weighted MRS with the sensitivity of DWI to gain insights on tissue microstructure beyond what each method can separately provide. Zoom link to join:https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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Nanoinclusions in diamonds: trapped fluids and solid molecular N2 and CO2

Date:

05

Tuesday

January

2021

Lecture / Seminar

Time: 11:00

Location: https://weizmann.zoom.us/j/7621438333?pwd=c0lpdlQzYSthellXWG9rZnM0ZDRFZz09

Lecturer: Oded Navon

Organizer: Department of Earth and Planetary Sciences

Abstract: Diamonds are perfect boxes for delivering samples of fluids and volatile species ... Read more

From design to optical properties in colloidal semiconductor nanocrystals

Date:

28

Monday

December

2020

Colloquium

Time: 11:00-12:00

Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09

Lecturer: Prof. Dan Oron

Organizer: Faculty of Chemistry

Contact: samzallag@gmail.com

Abstract: Colloidal semiconductor nanocrystals have turned over the past three decades fro ... Read more Colloidal semiconductor nanocrystals have turned over the past three decades from a scientific curiosity to a component in numerous commercial products, particularly in displays, lighting and light detection. On the one hand these are complex chemically synthesized entities, and on the other they behave, in many senses, as ‘giant’ artificial atoms. The interplay between these two enables us to imbue them with unique optical properties by design of their internal structure. I will go over some of our recent efforts in utilizing designer nanocrystals for various applications, including luminescence upconversion (the conversion of two low energy photons into a single high energy photon), electric field sensing and optical gain. Finally, I will discuss opportunities for the development of colloidal sources of non-classical states of light and our recent advances in quantum spectroscopy, enabling to study the optical and electronic properties of single quantum dots with unprecedented precision.

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Chemosignals are a form of human social communication

Date:

24

Thursday

December

2020

Lecture / Seminar

Time: 15:00-16:00

Lecturer: Eva Mishor (PhD Thesis Defense)

Organizer: Department of Brain Sciences

Details: Zoom link to join: https://weizmann.zoom.us/j/98031517872?pwd=U0EvNG5EdGJBL24zW ... Read more

Abstract: Although animals are known to heavily rely on chemical signals for intraspecies ... Read more Although animals are known to heavily rely on chemical signals for intraspecies communication, the matter of human chemical communication remains greatly contentious. I will present evidence supporting the claim that humans, just like other animals, rely on bodily-odors to effectively navigate the social world. First, I will present a quantification of people’s overt olfactory-sampling behavior. Of approximately 400 respondents, 94% acknowledged engaging in smelling their close relationships, and approximately 60% acknowledged sniffing strangers. Next, we tested if this olfactory information is employed for socially-relevant behavioral decisions, such as trust, a key element in human socialization. We found that subliminal exposure to body-odor increased implicit trustworthiness attributed to anthropomorphic non-humans. Finally, I will describe the effect of a specific body-volatile, Hexadecanal (HEX), on human impulsive aggression. Using validated behavioral paradigms, we observed a remarkable dissociation: sniffing HEX blocked aggression in men, but triggered aggression in women. Using functional brain imaging, we uncovered a pattern of brain activity mirroring behavior: In both men and women, HEX increased activity in an area implicated in the perception of social cues. Hex then modulated functional connectivity in a brain network implicated in aggressive behavior in a sex-dependent manner. Altogether, the thesis puts forward the hypothesis that chemosignals are a form of human social communication. Under this premise, human sampling behavior of self and others’ body-volatiles provides one with important information that, in turn, affects behaviors central to human society, such as trust and aggression. Zoom link to join: https://weizmann.zoom.us/j/98031517872?pwd=U0EvNG5EdGJBL24zWmpKUlY1akdnZz09 Meeting ID: 980 3151 7872 Password: 976632

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Behavioural signatures of a developing neural code

Date:

22

Tuesday

December

2020

Lecture / Seminar

Time: 12:30-13:30

Lecturer: Prof. Lilach Avitan

Organizer: Department of Brain Sciences

Details: Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laU ... Read more

Abstract: During early life the neural code must develop to appropriately transform sensor ... Read more During early life the neural code must develop to appropriately transform sensory inputs into behavioural outputs. However little is known about how developments in neural representations directly impact on behaviour. By combining behavioural analysis with 2-photon calcium imaging at multiple timepoints from 4 to 15 dpf in the optic tectum of developing zebrafish larvae, we demonstrate a link between the maturity of neural coding in the visual brain and developmental changes in visually-guided behavior. We show that visually-driven hunting behavior improves from 4 to 15 days post-fertilization, becoming faster and more accurate. During the same period population activity in parts of the optic tectum refines, improving decoding and information transmission for particular spatial positions. Together these results show that developmental signatures of an emerging neural code can be directly related to observable properties of behaviour. Please click the link below to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

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Zoom lecture: Nanoscale Optical Imaging Of Individual And Densely Packed Microgel Colloids

Date:

06

Sunday

December

2020

Lecture / Seminar

Time: 11:00-12:00

Lecturer: Prof. Frank Scheffold

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Zoom Link: https://weizmann.zoom.us/j/95267372668?pwd=dEhvRlA3SGtvVTQ1QnVmZ3JJ ... Read more Zoom Link: https://weizmann.zoom.us/j/95267372668?pwd=dEhvRlA3SGtvVTQ1QnVmZ3JJdTZEQT09 Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles uniquely. This study explores the frequency-dependent linear viscoelastic properties of dense suspensions of micron-sized microgels in conjunction with an analysis of the local particle structure and morphology-based on superresolution microscopy. By identifying the dominating mechanisms that control the elastic and dissipative response, we can explain these widely studied soft particle assemblies' rheology. Interestingly, our results suggest that the polymer brush-like corona's lubrification reduces friction between the microgel contacts.

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How cells determine their volume

Date:

30

Monday

November

2020

Colloquium

Time: 11:00-12:00

Location: https://weizmann.zoom.us/j/98063488104?pwd=N3VqTC9sU1A4RHVDZ1dhOGVxbU1iUT09

Lecturer: Prof. Sam Safran

Organizer: Faculty of Chemistry

Contact: samzallag@gmail.com

Abstract: Living cells regulate their volume using a diverse set of mechanisms, to maintai ... Read more Living cells regulate their volume using a diverse set of mechanisms, to maintain their structural and functional integrity. The most widely-used mechanism to control cell volume is active ion transport. Experiments on adhered cells surprisingly revealed that their volume is significantly reduced as their basal area is increased1. We have developed a physical theory2 which considers both electrostatics and cell activity to predict a generic relation for how adhered cells regulate their volume in response to changes in their area, in agreement with the observations. Those measurements also show that the nuclear volume scales with the cell volume. Recently, the Volk group3 using intact-organism imaging, discovered that changes in nuclear volume dramatically varies the spatial organization of chromatin (DNA and associated proteins); this may have important consequences for gene expression. A simple polymeric model4 that includes the competition of chromatin self-attraction and interactions with the nuclear membrane, predicts transitions in the chromatin organization relative to the nucleus from peripheral to central to conventional, as the nuclear volume is reduced, as measured in the experiments of the Volk group.

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Love thy neighbor - unraveling the tumor microenvironment by multiplexed imaging

Date:

17

Tuesday

November

2020

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Dr. Leeat Keren

Organizer: Department of Biomolecular Sciences

Abstract: Tumors are spatially organized ecosystems that are comprised of distinct cell ty ... Read more Tumors are spatially organized ecosystems that are comprised of distinct cell types, each of which can assume a variety of phenotypes defined by coexpression of multiple proteins. To underscore this complexity, and move beyond single cells to multicellular interactions, it is essential to interrogate cellular expression patterns within their native context in the tissue. We have pioneered MIBI-TOF (Multiplexed Ion Beam Imaging by Time of Flight), a platform that enables simultaneous imaging of forty proteins within intact tissue sections at subcellular resolution. In this talk, I will describe our application of multiplexed imaging to study the tumor immune microenvironment in triple negative breast cancer. Our work reveals archetypical organizations, linking molecular expression patterns, cell composition and histology, which are predictive of patient survival.

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Recent Advances in Flow and Imaging Flow Cytometry

Date:

05

Thursday

November

2020

Lecture / Seminar

Time: 09:00-10:00

Title: Briefs

Location: https://weizmann.zoom.us/j/96479787051?pwd=cGx2eHhNeEc3WE9sbnV1ZW1oYWI2QT09

Lecturer: Dr. Ziv Porat

Organizer: Department of Life Sciences Core Facilities

Contact: Ziv.Porat@weizmann.ac.il

Zoom lecture: Quantum sensor assisted magnetic resonance

Date:

15

Thursday

October

2020

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Prof. Ashok Ajoy

Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy

Details: Yeda Research and Development Ltd. is the commercial branch of the Weizmann Inst ... Read more

Abstract: Nuclear magnetic resonance (NMR) spectroscopy, is renowned for its high chemic ... Read more Nuclear magnetic resonance (NMR) spectroscopy, is renowned for its high chemical specificity, but suffers from low sensitivity and poor spatial resolution. This has largely locked up NMR in “central facilities”, where the measurement paradigm involves taking the sample to the NMR spectrometer. We are innovating a class of optical NMR probes that can allow one to invert this paradigm, effectively bringing the NMR spectrometer into the sample. This would open possibilities for NMR probes of analytes in their local environment. These “deployable” NMR sensors rely on a uniquely optically addressable spin platform constructed out of nanoparticles of diamonds, hosting defect centers (NV centers) and 13C nuclei. Such electron-nuclear spin hybrids serve dual-roles as optical “polarization injectors” and optical NMR detectors while also being targetable to within the sample of interest. I will focus on the main ingredients of this technology, while alluding to potential frontier applications opened as a result. Zoom link: https://weizmann.zoom.us/j/98496818322?pwd=RW03TWtTUUpKYXBXQlJtbnprMTRKdz09 passcode: 888482

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Visualizing Strongly-Interacting Quantum Matter

Date:

24

Thursday

September

2020

Colloquium

Time: 11:15-12:30

Location: https://weizmann.zoom.us/j/92790893230?pwd=VlRjVzkvaGZ5YWRvcXFGWXVXZ3dXdz09

Lecturer: Shahal Ilani

Organizer: Faculty of Physics

Microscopy and Spectroscopic Imaging of Nanostructures Conference website

Abstract: When quantum mechanics and Coulomb repulsion are combined in a pristine solid, s ... Read more When quantum mechanics and Coulomb repulsion are combined in a pristine solid, some of the most fascinating electronic phases in nature can emerge. Interactions between electrons can form correlated insulators, electronic liquids, and in extreme cases even quantum electronic solids. These phases are predicted to exhibit their most striking features in real-space, however, they are also extremely fragile, preventing their visualization with existing experimental tools. In this talk, I will describe our experiments that use a pristine carbon nanotube as a new type of a scanning probe, capable of imaging electrical charge with unprecedented sensitivity and minimal invasiveness. I will show how using this platform we were able to obtain the first images of the quantum crystal of electrons, visualize the collective hydrodynamic flow of interacting electrons in graphene, and unravel the parent state that underlies the physics of strongly-interacting electrons in the recently-discovered system of magic angle twisted bilayer graphene.

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Reversing personalized medicine

Date:

10

Thursday

September

2020

Lecture / Seminar

Time: 13:30-14:30

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Gal Markel

Organizer: Department of Biological Regulation

Contact: michal.av@weizmann.ac.il

Details: the link for the lecture's zoom room https://weizmann.zoom.us/j/5065402023?pwd= ... Read more

Abstract: Personalized medicine in oncology is focused on fitting drugs to the appropriat ... Read more Personalized medicine in oncology is focused on fitting drugs to the appropriate patients, mainly by identifying unique mutations in tumor genomics and development of highly selective drugs. The main challenge is that the relevant populations grow smaller, while development costs are constant, leading to significant reduction in effective drug development. The immune system provides personalized anti cancer response, and immune checkpoint inhibitors enable decent responses over a wide array of tumors. The outstanding challenge is that efficacy is observed in less than a third of the patients. Here we explore strategies to alter the patient in a way that will enable standard of care immunotherapy to exert its full potential, i.e. fitting the patients to the existing immunotherapeutic medications.

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Microscopy and Spectroscopic Imaging of Nanostructures

Date:

03

Thursday

September

2020

Conference

Time: 08:00-18:00

Location: Gerhard M.J. Schmidt Lecture Hall

Contact: reshef.tenne@weizmann.ac.il

Structure Sensitivity in Catalysis

Date:

23

Sunday

August

2020

Lecture / Seminar

Time: 14:00-15:00

Title: Joint special seminar of the depts. of Organic Chemistry & Materials and Interfaces

Location: https://weizmann.zoom.us/j/95177555007?pwd=aDE5V2FVL2hRSDB5cFFuMTRQckViZz09

Lecturer: Dr. Charlotte Vogt

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Some fundamental concepts of catalysis are as of yet not fully explained but are ... Read more Some fundamental concepts of catalysis are as of yet not fully explained but are of paramount importance for the development of improved supported metal catalysts for chemical industries and environmental remediation. Structure (in)sensitivity is such a fundamental physical concept in catalysis, which relates the rate of a catalytic reaction per unit surface area to the size of a nanoparticle. If this rate per unit surface area changes with catalyst particle size, a reaction is termed structure sensitive. Conversely if it does not - a reaction is termed structure insensitive. Historically, many fundamental physical concepts explaining the behavior of metal nanoparticular catalysts have been formulated by studying single crystal facets with surface science techniques which has left a considerable gap in our basic knowledge of catalysts at work. By using and developing state-of-the-art operando (micro)spectroscopic techniques, inter alia operando high-temperature high-pressure FT-IR, in-situ high-resolution STEM, and quick-X-ray absorption spectroscopy (quick-XAS) with millisecond time resolution, over the last few years I have been exploring the fundamental physical concepts behind fundamental structure-activity relationships of catalytic reactions by studying non-model catalysts at work. For example, by applying these methods to study a structure sensitive reaction (carbon dioxide hydrogenation) to a structure insensitive one (ethene hydrogenation) we show that the same geometric and electronic effects that we find to explain structure sensitivity make it unlikely for structure insensitivity to exist (while we do observe it empirically). However, interestingly, in the case of the structure insensitive ethene hydrogenation reaction, such size-dependent nanoparticle restructuring effects as the decrease of the reversibility of adsorbate-induced restructuring and the increase of carbon diffusion with increasing particle size are observed by quick-XAS (see Figure 1). While for the structure sensitive CO2 hydrogenation no such perturbation was observed. We further show that this particle size dependent restructuring induced by ethene hydrogenation can make a structure sensitive reaction structure insensitive. Hence, we may postulate that structure insensitive reactions should rather be termed apparently structure insensitive, which changes our fundamental understanding of the age-old empirical observation of structure insensitivity.

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ClearSight™: A portable system that uses diffusion NMR to probe the margins of excised tumors

Date:

16

Thursday

July

2020

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Dr. Saul Stokar

Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy

Abstract: Zoom link: https://weizmann.zoom.us/j/91154950215?pwd=ZkRsTWJzL1AzMWpNbFVSVUF4d0 ... Read more Zoom link: https://weizmann.zoom.us/j/91154950215?pwd=ZkRsTWJzL1AzMWpNbFVSVUF4d05zQT09 Password: 388848 Diffusion NMR weighted NMR and MRI are very powerful techniques for investigating microscopic details about tissue architecture, either normal or in a diseased state. In addition to its traditional use in diagnosing stroke and ischemic injury in the brain, in recent years DWI has been used to diagnose various kinds of cancer, including breast, prostate and lung cancers. In this seminar we will present an overview of a novel portable system that uses DWI to check whether the margins of excised breast tumors are tumor-free. This is extremely important both for the patient and the hospital, since it obviates the need to perform additional surgery if the subsequent pathology indicates the presence of tumor on the margin of the excised tissue, something that occurs today in up to 25% of breast-conserving surgeries. We shall provide an overview of diffusion MRI, the unique challenges of performing MRI in or near the operating theater, the architecture of ClearCut's system, computer simulations of its performance and an overview of the clinical results obtained to date.

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The power of ONE: Immunology in the age of single cell genomics

Date:

02

Thursday

July

2020

Lecture / Seminar

Time: 14:00-15:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Ido Amit

Organizer: Dwek Institute for Cancer Therapy Research

Contact: yam.nof@weizmann.ac.il

Sparsity-based Methods for Rapid MRI

Date:

25

Thursday

June

2020

Lecture / Seminar

Time: 09:30-10:30

Lecturer: Dr. Efrat Shimron

Organizer: Clore Institute for High-Field Magnetic Resonance Imaging and Spectroscopy

Abstract: Zoom Lecture: https://weizmann.zoom.us/j/99058507421 Magnetic Resonance Ima ... Read more Zoom Lecture: https://weizmann.zoom.us/j/99058507421 Magnetic Resonance Imaging (MRI) is a superb imaging modality that provides high-quality images of the human body. However, one of its major limitations is the long acquisition time, which hinders the MRI clinical use. The acquisition time can be shortened by acquiring less data; however, this requires suitable methods for accurate image reconstruction from subsampled data, which is acquired with a sub-Nyquist rate. In this seminar, four novel methods for image reconstruction from subsampled data will be presented. These methods build upon the well-established frameworks of Parallel Imaging (PI) and Compressed Sensing (CS), utilize a-priori knowledge about data sparsity, and address current limitations of PI-CS methods. The first two methods accelerate static MRI scans by introducing the Convolution-based Reconstruction (CORE) framework, which offers a parameter-free non-iterative reconstruction. Experiments with in-vivo 7T brain data demonstrated that these methods perform comparably to the well-established GRAPPA and l1-SPIRiT methods, with the advantage of shorter computation times and reduced need for parameter calibration. The next two developed methods accelerate dynamic MRI scans that provide temperature monitoring in High Intensity Focused Ultrasound (MRgHIFU) thermal ablation treatments. The developed methods enable rapid MR monitoring by reconstructing temperature changes from subsampled data. Validation experiments were performed with in-vivo data from clinical treatments of prostate cancer in humans; these showed that the proposed methods significantly outperform two state-of-the-art methods in the temperature reconstruction task

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Vesicle membrane ‘quarantine’ by mechanochemical insulation maintains apical membrane homeostasis during exocytosis

Date:

16

Tuesday

June

2020

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Kamalesh Kumari

Organizer: Department of Biomolecular Sciences

Abstract: Exocrine glands in our bodies secret copious amounts of cargo (like- sweat, sali ... Read more Exocrine glands in our bodies secret copious amounts of cargo (like- sweat, saliva, digestive enzymes, chemokines, etc.) via. giant secretory vesicles, that are micron-scale in diameter. During the secretion of these giant vesicles, a large amount of the membrane is constantly added to the apical surface of the cells that can perturb its size, composition, and function that are vital to cell survival. Hemostatic maintenance of the cell surface in terms of size, shape, and composition is extremely challenging in the face of continuous secretion, which what we ventured to understand. We use a combination live-cell imaging and correlative light and electron microscopy (CLEM) approach, to uncover a novel a mechanism of exocytosis allowing the secretory cells to maintain membrane homeostasis during secretion. I will present to you data to describe what we call as - the crumpling and sequestration model of exocytosis.

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Cancer Research Club - Prof Dan Landau: Novel genomics perspectives on cancer evolution: from basic principles to therapeutic optimization

Date:

04

Thursday

June

2020

Lecture / Seminar

Time: 14:00-15:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Dan Landau

Organizer: Department of Biological Regulation

Contact: yam.nof@weizmann.ac.il

Mass Photometry – a new way to study biomolecules

Date:

02

Tuesday

June

2020

Lecture / Seminar

Time: 10:00-10:45

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Adar Sonn-Segev

Organizer: Department of Biomolecular Sciences

Abstract: One of the main challenges of researchers that utilize purified proteins for in- ... Read more One of the main challenges of researchers that utilize purified proteins for in-vitro assays is the characterization of the purity and heterogeneity of their proteins in solution. To find out this information, you can employ native gel electrophoresis, gel-filtration chromatography, dynamic light scattering or mass spectroscopy. While some of these methods have low resolution and require large amounts of protein, others are time consuming and require a lot of knowledge to operate and interpret. Mass photometry is a new ground-breaking tool to analyze biomolecules. It is based on interferometric scattering microscopy and enables the accurate mass measurement of single molecules in solution, in their native state without the need for labels, and provides results within minutes. It provides a rapid, accurate and simple analysis of the oligomeric state of proteins in solution. In fact, mass photometry offers optimal conditions for studying sample heterogeneity, protein-protein and protein-nucleic acid interactions, protein oligomerization, macromolecular assemblies many more. Mass photometry represents a truly novel approach for the analysis of individual biomolecules in solution. I will illustrate the unique capabilities of mass photometry by discussing a broad selection of recently published examples and provide insight into the strengths and limitations of this approach. * Weizmann Institute has collaborated with Refeyn Ltd to make mass photometry available to all Weizmann research community, with an on-site specialist, Dr. Adar Sonn-Segev, to help with its implementation.

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Chemistry Colloquium

Date:

11

Monday

May

2020

Colloquium

Time: 11:00-12:15

Title: The Macromolecular Structure of Mucus, Our Bodies’ First Line of Defense Against Pathogens

Location: https://weizmann.zoom.us/j/92049901272

Lecturer: Prof. Debbie Fass

Organizer: Faculty of Chemistry

Contact: yael.lepek@weizmann.ac.il

Abstract: Respiratory viruses such as coronavirus spread from person to person through dro ... Read more Respiratory viruses such as coronavirus spread from person to person through droplets of saliva or mucus. Face masks decrease the dissemination of such droplets and thereby minimize viral propagation from someone who may be contagious. Mucus did not evolve, though, to help pathogens spread. Quite the opposite. Mucus arose early in the evolution of multicellular animals to exclude undesirable bacteria from body tissues, a primitive type of immunity. The cooperation between cilia* and mucus also helped prevent aquatic organisms from being smothered by sediments and enabled them to clean or collect particulate matter from their exteriors. Producing mucus was likely a prerequisite for evolution of the gut and of the types of respiratory organs necessary for terrestrial life. Today, mucus protects the large, exposed interior surfaces of our respiratory and gastrointestinal tracts from bacteria, viruses, parasites, and chemical/physical hazards. But what material is mucus? Mucus is a hydrogel made of heavily glycosylated protein molecules called “mucins,” each of which is nearly 3 megadaltons in size. Individual giant mucin molecules are disulfide bonded to one another, generating an extended mesh. Using cryo-electron microscopy and X-ray crystallography, we have discovered the three-dimensional structure of mucins and gained insight into the mechanism by which they assemble step-wise into hydrogels. ______________________________________________________ * cell-surface, rope-like structures that beat in coordinated waves

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Canceled: Nanoscale Electronic Phenomena in Ferroelectric Thin Films

Date:

18

Wednesday

March

2020

Lecture / Seminar

Time: 11:00-12:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Alexei Gruverman

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: This seminar consists of two parts. The first part is related to the investigati ... Read more This seminar consists of two parts. The first part is related to the investigation of mechanism of tunable domain wall (DW) conductivity in the ferroelectric LiNbO3 thin films with sub-µm thickness, Using a combination of scanning transmission electron microscopy (STEM) and local probe techniques we generate and delineate the electrically-charged 180º DWs and test their conducting behavior using local probe spectroscopy and imaging under electrical bias. More importantly, electrical tunability of DW conductivity by sub-coercive voltage is realized through the changes in DW conformity. The obtained results provide tangible evidence that the charged DWs can be used as multilevel logic elements in analog computing devices. The second part discusses the dynamic switching behavior in the HfO2-based films investigated by a combination of local probe microscopy and pulse switching techniques. Application of HfO2-based materials to ferroelectric memory and logic devices has generated considerable interest as they allow overcoming significant problems associated with poor compatibility of perovskite ferroelectrics with CMOS processing. High-resolution studies of the time- and field-dependent evolution of the domain structure in La:HfO2 thin film capacitors provides an insight into the mechanism of imprint - one of the main degradation effects hindering integration of ferroelectric HfO2 into CMOS-compatible memory technology.

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Recovering Lost Information in the Digital World

Date:

15

Sunday

March

2020

Lecture / Seminar

Time: 13:15

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Yonina Eldar, WIS

Organizer: Department of Physics of Complex Systems

Contact: perla.zalcberg@weizmann.ac.il

Abstract: The conversion of physical analog signals to the digital domain for further proc ... Read more The conversion of physical analog signals to the digital domain for further processing inevitably entails loss of information.The famous Shannon-Nyquist theorem has become a landmark in analog to digital conversion and the development of digital signal processing algorithms. However, in many modern applications, the signal bandwidths have increased tremendously, while the acquisition capabilities have not scaled sufficiently fast. Furthermore, the resulting high rate digital data requires storage, communication and processing at very high rates which is computationally expensive and requires large amounts of power. In this talk, we present a framework for sampling and processing a wide class of wideband analog signals at rates far below Nyquist by exploiting signal structure and the processing task. We then show how these ideas can be used to overcome fundamental resolution limits in optical microscopy, ultrasound imaging, quantum systems and more. We demonstrate the theory through several demos of real-time sub-Nyquist prototypes and devices operating beyond the standard resolution limits combining high spatial resolution with short integration time.

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MR spectroscopy at 7 tesla – initial experiences in Glasgow

Date:

05

Thursday

March

2020

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr Graeme Keith

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Much has been written of the potential of ultra-high field MR scanners, such as ... Read more Much has been written of the potential of ultra-high field MR scanners, such as 7 tesla, due to their inherently higher signal-to-noise ratio (SNR). This native boost is of great use in making techniques that operate in a low SNR regime, such as spectroscopy, more viable. Application of spectroscopic techniques at 7 tesla also come with a secondary, yet perhaps more important benefit in increased spectral resolution. This can allow for the quantitative investigation of metabolites that are difficult to resolve and measure reliably at lower field strengths. This seminar will relate early experiences in spectroscopy from the Siemens Terra 7T system at the University of Glasgow. This will include the optimisation of single voxel techniques for clinical studies, such as the measurement of glutamate in neuroinflammatory conditions, as well as an update on development work, such as a spectral 2D correlated spectroscopy (COSY) acquisition for investigation of glioma tumours, including a focus on 2-hydorxyglutarate. It will also cover the development of a novel MR spectroscopic imaging (MRSI) technique based on the EPSI sequence, which will allow for high resolution, full spectral bandwidth 7T acquisitions in a clinically viable time, by application of compressed sensing methods

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From Cognition to Depression: Using Magnetic Resonance Spectroscopy to Study In-vivo Neurochemistry

Date:

03

Tuesday

March

2020

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Assaf Tal

Organizer: Department of Brain Sciences

Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance wit ... Read more

Abstract: Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concent ... Read more Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concentrations of several metabolites in the brain non-invasively. I will present our work using MRS to study two aspects of brain metabolism. First, I'll talk about our work on functional MRS, whereby we look at neurochemical changes during or after learning or function. In the second half of the talk, I will focus on new methods we're developing in the lab, and in particular on our ability to measure the thermal relaxation times of metabolites, which probe specific cellular and subcellular microenvironments. I will present some preliminary data showing where and how this could be useful.

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Chemical Biology Seminar Series

Date:

27

Thursday

February

2020

Lecture / Seminar

Time: 14:00-15:00

Title: In Vivo Chemical Probes for MRI and Fluorescence Imaging

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Kazuya Kikuchi

Organizer: The Dr. Barry Sherman Institute for Medicinal Chemistry

The Biological Age Concept: Predicting Healthspan and Lifespan using Genomics, Epigenomics and Proteomics from Saliva and Plasma

Date:

27

Thursday

February

2020

Lecture / Seminar

Time: 14:00-15:00

Title: Guest Talk with Prof Jaap Goudsmit

Lecturer: Prof. Jaap Goudsmit

Organizer: Department of Molecular Cell Biology

Contact: sigal.laor-shoham@weizmann.ac.il

Details: The Biological Age Concept: Predicting Healthspan and Lifespan using Genomics, E ... Read more

Assurance of Clonality Next-Generation Single-Cell Dispensing in Cell Line Development and Single-Cell Genomics

Date:

24

Monday

February

2020

Lecture / Seminar

Time: 10:00-11:00

Title: Presentation & ‘Cytena f.sight’ hands-on

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Dr. Adrian Zambrano

Organizer: Department of Life Sciences Core Facilities

Contact: elena.ainbinder@weizmann.ac.il

Looking into the rocks of Acheulo-Yabrudian Qesem Cave (Israel, 420-200 kya)

Date:

20

Thursday

February

2020

Lecture / Seminar

Time: 11:30-12:30

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Aviad Agam

Organizer: Academic Educational Research

Contact: lior.regev@weizmann.ac.il

Abstract: The Acheulo-Yabrudian Cultural Complex (AYCC, ~420,000-200,000 years ago) is a l ... Read more The Acheulo-Yabrudian Cultural Complex (AYCC, ~420,000-200,000 years ago) is a local Levantine entity, characterized by a set of innovative human cultural and biological adaptations, including the habitual use of fire, technological innovations such as blade and Quina scraper production, and more. Qesem Cave (QC, central Israel) is one of the key sites of the AYCC. I will present the results of two recent studies, exploring the rich lithic assemblages yielded from this important site. The first combines macroscopic classification of flint artefacts with a geological survey and petrographic and geochemical analyses, aimed at identifying patterns of flint acquisition and use. The results show that local Turonian flint was often brought and used at the cave, while flint from other, non-Turonian origins, was also used in noteworthy proportions, in specific categories, implying selectivity in flint procurement and exploitation through time. The second study combines Raman spectroscopy and artificial intelligence (AI) to build temperature predictive models, aimed at identifying the temperatures to which flint artefacts were exposed. The results show that blades were heated at lower median temperatures (259℃) compared to flakes (413℃), suggesting the intentional and controlled heat treatment of flint specifically for blade production, more than 300,000 years ago. Both datasets and their implications will be discussed in a broader perspective.

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M.Sc thesis defense: "The origin of anharmonic atomic motion in halide perovskite crystals"

Date:

13

Thursday

February

2020

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Adi Cohen

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Halide perovskites (ABX3) attracted much of attention in the last years due to t ... Read more Halide perovskites (ABX3) attracted much of attention in the last years due to their excellent photovoltaic activity. They are unique in the sense that they exhibit long carrier lifetime despite having many apparent structural defects. Recent studies in our group concluded that this unique behavior is due to strong coupling between the electronic band structure and the strongly anharmonic motion of the atoms within the crystal. Therefore, it is imperative to understand the source of anharmonic atomic motion in this class of materials. Studies have indicated the B-cation lone pair to be a possible source for strong anharmonic behavior in the perovskite crystals. In order to understand the anharmonic behavior and its origin, I investigated a series of perovskites with different lone pair stereoactivity. Using low frequency Raman spectroscopy, I quantified the level of anharmonicity and determined the influence of the B-cation lone pair on the structural dynamics.

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The Genomics of Fasting and Inflammation Reveals Dynamic Cooperativity Between Transcription Factors

Date:

09

Sunday

February

2020

Lecture / Seminar

Time: 15:00-16:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Ido Goldstein

Organizer: Life Sciences

Contact: yael.kuperman@weizmann.ac.il

The earliest evidence of a Lisfranc’s fracture

Date:

06

Thursday

February

2020

Lecture / Seminar

Time: 11:30-12:30

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Sara Borgel

Organizer: Academic Educational Research

Contact: lior.regev@weizmann.ac.il

Abstract: Recent archaeological excavations at Manot Cave, an Early Upper Palaeolithic sit ... Read more Recent archaeological excavations at Manot Cave, an Early Upper Palaeolithic site in the Western Galilee, Israel, retrieved the remains of a partial left foot of a young adult, including the talus, the calcaneus, the cuboid and the first, second and fifth metatarsals. The pedal remains were found close to one another, in the same archaeological unit, and were associated with an Early Upper Palaeolithic assemblage. Our study aimed at describing the anatomy of the Manot Cave pedal bones using morphometric parameters. A comparison to foot bones of recent modern humans, Anatomically Modern Humans and Neanderthals was carried out to establish the Manot Cave specimen population affiliation. Additionally, µCT images were used to verify a suspected injury in the base of the second metatarsal. The shape and size of the Manot pedal bones indicated a modern morphology for all bones, albeit few Neanderthal-like characteristics. Imaging analysis confirmed the existence of a healed trauma in the second metatarsal, with the plantar third of the base misaligned with the shaft and a fracture line on the lateral side. These features are consistent with a fracture known as Lisfranc’s fracture, most probably caused by an impact to the dorsum of the foot. This injury usually leads to ligamentous instability and collapse of the transverse and longitudinal arches, causing severe walking difficulties. Full recovery requires rest and immobility for several weeks. As mobility was crucial to maintain the hunter-gatherer lifeway of this group, the survival of this individual indicates a supportive community at Manot Cave.

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Whole-brain fMRI of the Behaving Mouse

Date:

04

Tuesday

February

2020

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Itamar Kahn

Organizer: Department of Brain Sciences

Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance wit ... Read more

Abstract: Functional MRI is used pervasively in human brain research, enabling characteriz ... Read more Functional MRI is used pervasively in human brain research, enabling characterization of distributed brain activity underlying complex perceptual and cognitive processes. However, heretofore this technique has been limited in utility in rodents. I will present whole-brain functional imaging of head-fixed mice performing go/no-go odor discrimination in a platform allowing precise odor-delivery system, non-invasive sniff recordings and lick detection, detailing the brain regions subserving this behavior from the naïve state to task proficiency including learning of rule reversal. I will briefly discuss efforts to expand the mouse fMRI platform to additional modalities and conclude by describing the prospects of this approach more broadly.

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Imaging single cells in live models for neurodevelopmental and sleep disorders

Date:

28

Tuesday

January

2020

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Lior Applebaum

Organizer: Department of Brain Sciences

Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For accessibility ... Read more

Catalyst Images, Imaging and Imagination: Visualizing Molecules and Atoms in Action on Catalytic Surfaces

Date:

28

Tuesday

January

2020

Lecture / Seminar

Time: 11:00-12:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Bert M. Weckhuysen

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Catalysts play a pivotal role in modern society since they enable the production ... Read more Catalysts play a pivotal role in modern society since they enable the production of chemicals and fuels that we rely on every day. The search for new and improved solid catalysts to speed up and access novel chemical reactions is a never-ending challenge, but has become increasingly important due to the environmental challenges that we are currently facing. For this purpose, constant improvements in synthesis methods are required in general, but more specifically, improvements in characterization methods in terms of spatiotemporal resolution is the key toward tailored catalytic reactions. In an ideal case, a real time visualization of the reactants, intermediates and reaction products on the surface of the catalyst is possible, allowing for a molecular movie of the catalytic reaction in space and time. Certain characterization techniques exist that are sensitive enough to measure the reactants at the reaction surface of the catalyst (e.g. vibrational spectroscopy). However, in order to really understand the catalytic behaviour, we need to move toward single molecules and atoms at the (sub-) nanometer scale. Improvements in this direction have already led to an increased understanding of the catalytic processes, but the combination of nanometer resolution in space and pico- to nanosecond resolution in time has remained largely elusive in the world of heterogeneous catalysis. In this lecture, I will discuss the state-of-the-art of time- and space-resolved spectroscopy and microscopy methods for catalysis research, and discuss the movement in the field toward the visualization of individual molecules at catalyst surfaces to construct the ultimate “molecular movie of sustainability” (Figure 1). Special emphasis will be on the compatibility of operando characterization techniques with the desired reaction environment (e.g. liquid or gas phase) and what we can do to ensure the spatiotemporal resolution is not hampered by the reaction requirements of the catalytic reactions. I will touch upon a variety of techniques, ranging from (time-resolved and surface-enhanced) vibrational spectroscopy, single molecule fluorescence, scanning probe techniques combined with optical and vibrational spectroscopy, as well as X-ray spectroscopy and microscopy.

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Chemical and Biological Physics Dept Seminar

Date:

28

Tuesday

January

2020

Lecture / Seminar

Time: 11:00

Title: Wide-Field Single Photon-Counting Imaging for Fast and Highly Sensitive In Vivo Cell Tracking

Location: Perlman Chemical Sciences Building

Lecturer: Dr Rinat Ankri

Organizer: Department of Chemical and Biological Physics

Contact: lucio.frydman@weizmann.ac.il

Abstract: Biomolecular imaging at the preclinical stage is an essential tool in various bi ... Read more Biomolecular imaging at the preclinical stage is an essential tool in various biomedical research areas such as immunology, oncology or neurology. Among all modalities available to date, optical imaging techniques play a central role, while fluorescence, in particular in the NIR region of the spectrum, provides high sensitivity and high specificity with relatively cheap instrumentation. Several whole-body optical pre-clinical NIR imaging systems are commercially available. Instruments using continuous wave (CW or time-independent) illumination allow basic small animal imaging at low cost. However, CW techniques cannot provide fluorescence lifetime contrast, which allows to probe the microenvironment and affords an increased multiplexing power. In the first part of my talk I will introduce our single photon, time-gated, phasor-based fluorescence lifetime Imaging method which circumvents limitations of conventional techniques in speed, specificity and ease of use, using fluorescent lifetime as the main contrast mechanism. In the second part of my talk I will present the tracking and multiplexing of two different cell populations, based on their different lifetimes (following their fluorescent dyes-loading). Despite major advantages of optical based NIR imaging, the reason that NIR imagers are not clinically used, is that only very few such fluorescent molecules absorb and emit in the NIR (or in the shortwave infrared, SWIR region), and even fewer have favorable biological properties (and FDA approval). I will introduce small lung cancer and dendritic cells tracking using small polyethylene glycol/phosphatidylethanolamine (PEG–PE) micelles loaded with NIR dyes (using commercial dyes as well as dyes synthesized in Prof. Sletten’s lab, UCLA Chemistry Dept.). Micelles’ endocytosis into cells affords efficient loading and exhibits strong bio stability, enabling to track the loaded cells for several days using these formulations, even though dyes were diluted by cells division (leading to reduced dye concentration within the dividing cells). Moreover, fluorescent lifetime contrast (achieved through our time-gated imaging method), significantly improved these cells detection. These advances in NIR fluorescence based imaging open up new avenues toward NIR and SWIR imaging for biomedical applications, such as tracking and monitoring cells during immunotherapy and/or drug delivery (treatment monitoring) for various types of disease.

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Chemical and Biological Physics Guest Seminar

Date:

26

Sunday

January

2020

Lecture / Seminar

Time: 14:00-15:00

Title: Non-Genetic “Optogenetics”: Silicon Based Bio-Interfaces for Multi-scale Optical Modulation

Location: Perlman Chemical Sciences Building

Lecturer: Dr Menahem (Hemi) Rotenberg

Organizer: Department of Chemical and Biological Physics

Contact: lucio.frydman@weizmann.ac.il

Abstract: Bioelectronics for cellular interrogation requires a minimally invasive introduc ... Read more Bioelectronics for cellular interrogation requires a minimally invasive introduction of an electrical probe to the cell. Despite tremendous developments in the field of electroceuticals in the past decades, the available technologies are still associated with major limitations. Micropipette electrodes, micro- and nanoelectrode arrays, and nano-field effect transistors allow intracellular access with extremely high spatial resolution. However, these technologies are substrate-bound, do not allow reconfigurable recording or stimulation, and lack deep tissue access, which limits their use to in vitro application. Optogenetics can offer numerous mechanistic insights into cellular processes, but its spatial resolution is limited, especially for 3D tissues. Moreover, it requires genetic modification, which limits its potential therapeutic applications. In this talk, I will present my recent studies of developing new approaches for bio-interfaces using silicon micro- and nanostructures for non-genetic optical modulation, spanning from sub cellular interrogation with extremely high spatial resolutions to whole organ optical modulation. For sub-cellular interrogation, we used tailored made photovoltaic silicon nanowires with p-i-n core-shell design. These nanowires were hybridized with living myofibroblasts and used as free sanding cell-silicon hybrids with leadless optical modulation capabilities. We used focused laser to perform intracellular electrical interrogation with high, sub-cellular spatial resolution. Thereafter, we used these hybrids to tackle a long-standing debate regarding electrical coupling between myofibroblasts and cardiomyocytes in vivo, by interrogating specific myofibroblasts within the 3D volume of the cardiac tissue. We also show this technology’s utility for neuronal investigation by hybridizing myelinating oligodendrocytes and interfacing them with neurons, allowing the investigation of calcium transients’ role in the myelination process with unprecedented spatial control. For whole organ interface we used flexible single crystalline silicon membranes, that were able to adhere and wrap around the heart and sciatic nerve. We used optical stimulation to perform heart pacing at different location on the heart, and sciatic nerve excitation. These results demonstrate potential biomedical applications for cardiac resynchronization therapy and sciatic nerve neuro-regenerative treatments.

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Visualizing activity dependent signaling dynamics in intact neuronal circuits

Date:

21

Tuesday

January

2020

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Tal Laviv

Organizer: Department of Brain Sciences

Details: Joint Seminar-Depts of Neurobiology & Biomolecular Sciences Hosts: Prof. Ro ... Read more

Abstract: Sensory experience can change the structure and function of neurons in the bra ... Read more Sensory experience can change the structure and function of neurons in the brain over a wide range of timescales, from milliseconds-second modulation of synaptic activity to long-lasting alterations of genetic programs, lasting minutes to hours. While conversion of synaptic activity into long-lasting nuclear signaling is vital for learning and neuronal development, we still lack a clear understanding of its basic operating principles. To address this, I will describe recent advancements using two-photon fluorescence lifetime imaging and new biosensors which allowed us to image the activity of CREB, an activity-dependent transcription factor important for synaptic plasticity, at single cell resolution in awake mice. Simultaneous imaging of CREB and Ca2+ in the visual cortex permitted us to explore how sensory deprivation (dark-rearing) can modulate the sensitivity and duration of CREB activity to sensory-evoked Ca2+ elevations. Future work using this approach will allow us to unravel synapse to nucleus signaling dynamics underlying experience-dependent plasticity in the brain.

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Visualizing activity dependent signaling dynamics in intact neuronal circuits

Date:

21

Tuesday

January

2020

Lecture / Seminar

Time: 12:30-13:30

Title: Joint Seminar - Dept. of Neurobiology & Biomolecular Sciences

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Tal Laviv - Joint Seminar - Dept. of Neurobiology & Biomolecular Sciences

Organizer: Department of Biomolecular Sciences

Abstract: Sensory experience can change the structure and function of neurons in the brain ... Read more Sensory experience can change the structure and function of neurons in the brain over a wide range of timescales, from milliseconds-second modulation of synaptic activity to long-lasting alterations of genetic programs, lasting minutes to hours. While conversion of synaptic activity into long-lasting nuclear signaling is vital for learning and neuronal development, we still lack a clear understanding of its basic operating principles. To address this, I will describe recent advancements using two-photon fluorescence lifetime imaging and new biosensors which allowed us to image the activity of CREB, an activity-dependent transcription factor important for synaptic plasticity, at single cell resolution in awake mice. Simultaneous imaging of CREB and Ca2+ in the visual cortex permitted us to explore how sensory deprivation (dark-rearing) can modulate the sensitivity and duration of CREB activity to sensory-evoked Ca2+ elevations. Future work using this approach will allow us to unravel synapse to nucleus signaling dynamics underlying experience-dependent plasticity in the brain.

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Soil Spectroscopy throughout the Years: Availabilities and Capabilities

Date:

19

Sunday

January

2020

Lecture / Seminar

Time: 11:00

Location: Sussman Family Building for Environmental Sciences

Lecturer: Eyal Ben-Dor

Organizer: Department of Earth and Planetary Sciences

Abstract: The soil spectroscopy discipline has been progressed over the past two decades q ... Read more The soil spectroscopy discipline has been progressed over the past two decades quite remarkably. Many portable point spectrometers became available through that time where recently also image spectrometers have become quite popular. The technology was used in the laboratory, field, and airborne levels and provided a new capability for a rapid and quantitative view of a large number of samples. At the same time platforms were also developed to carry the new family of sensors for remote sensing applications of large areas using ground and airborne vehicles ( manned and un-manned) and recently even satellites. This progress has led to a large number of activities in exploiting the spectroscopy for many applications within the soil science discipline. As the data acquisition increases and the soil spectral database has been enlarged, a new technique to compile soil spectral database together with methods to effectively analyze them has also been developed. To that end, activities to deal with the data mining process using big databases were successfully adopted from other disciplines while also designed especially for the soil spectroscopy activity. The results demonstrated that soil spectroscopy could be used for many applications from different domains such as soil mapping, precision agriculture, and laboratory work and can progress the soil science discipline quite forward. In this talk, we will review the history of soil spectroscopy from the first spectrometer and platform to the present situation. A particular emphasis will be given to the recent applications that have been developed in our group and to the future capability of this critical technology from all perspectives and to the new horizon it may open as expressed by space agencies such as NASA, ESA, ASI, JAXA, ISA and DLR.

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From connectome to function: connectivity features underlying neuronal population dynamics in the nematode C. elegans

Date:

14

Tuesday

January

2020

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Manuel Zimmer

Organizer: Department of Brain Sciences

Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance w ... Read more

Abstract: A fundamental problem in neuroscience is to elucidate the relationship between n ... Read more A fundamental problem in neuroscience is to elucidate the relationship between neuronal network anatomy and its functional dynamics. The nematode worm C. elegans is an ideal model to study these problems. Its nervous system has just 302 neurons and all synaptic connections between them have been fully mapped. Using a large-scale Ca2+-imaging approach, we previously discovered nervous system wide neuronal population dynamics in the worm that encode action commands. These dynamics feature various network attractor states during which neurons coordinate and synchronize their activities, thereby providing functional interaction maps. In this talk, I will discuss unpublished work where we combine graph-theoretical and experimental approaches to understand which anatomical features in network connectivity relate to these functional dynamics and interactions between neurons.

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Chemical and Biological Physics Guest Seminar

Date:

14

Tuesday

January

2020

Lecture / Seminar

Time: 11:00-12:00

Title: Emerging exotic quantum phenomena in 1D molecular chains on surfaces

Location: Perlman Chemical Sciences Building

Lecturer: Dr Pavel Jelinek

Organizer: Department of Chemical and Biological Physics

Contact: oren.tal@weizmann.ac.il

Abstract: Low dimensional materials offer very interesting material and physical propertie ... Read more Low dimensional materials offer very interesting material and physical properties due to reduced dimensionality. Nowadays, mostly 2D materials are the focus of attention. However, 1D systems often show far more exotic behavior, such as Tomanaga-Luttinger liquid, Peierls distortion, etc.. In this talk, we will present different classes of 1D molecular chains formed on metallic surfaces by on-surface synthesis, which physical and chemical properties were investigated by low temperature UHV scanning probe microscopy supported by theoretical analysis. First, we will introduce a novel strategy to synthesize [1] a new class of intrinsically quasi-metallic one-dimensional (1D) -conjugated polymers featuring topologically non-trivial quantum states. Furthermore, we unveiled the fundamental relation between quantum topology, -conjugation and metallicity of polymers [2]. Thus, we will make a connection between two distinct worlds of topological band theory (condensed matter physics) and -conjugation polymer science (chemistry). We strongly believe this may stimulate new ways of thinking towards a design of novel organic quantum materials. In second part, we will demonstrate unusual mechanical and electronic properties of hydrogen bonded chains formed on a metallic surface driven by quantum nuclaar effects within the chain. We will show, that the concerted proton tunneling not only enhances the mechanical stability of the chain, but it also gives rise to new in-band gap electronics states localized at the ends of the chain. [1] A. Grande-Sanchez et al. Angew. Chem. Int. Ed. 131, 6631-6635 (2019). [2] B. Cierra et al arXiv preprint arXiv:1911.05514

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Chemical and Biological Physics Guest Seminar

Date:

12

Sunday

January

2020

Lecture / Seminar

Time: 14:00

Title: Allosteric signal propagation studied by transient IR spectroscopy

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Peter Hamm

Organizer: Department of Chemical and Biological Physics

Contact: gilad.haran@weizmann.ac.il

Denise Cai: Linking memories across time and by Tristan Shuman: Breakdown of spatial coding and interneuron synchronization in epileptic mice

Date:

09

Thursday

January

2020

Lecture / Seminar

Time: 14:30-15:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Denise Cai and Tristan Shuman

Organizer: Department of Brain Sciences

Details: Back-to-back Talk (1-hour long in total) Host: Prof. Nachum Ulanovsky nachum. ... Read more

Abstract: Denise Cai: Linking memories across time The compilation of memories, collecte ... Read more Denise Cai: Linking memories across time The compilation of memories, collected and aggregated across a lifetime defines our human experience. My lab is interested in dissecting how memories are stored, updated, integrated and retrieved across a lifetime. Recent studies suggest that a shared neural ensemble may link distinct memories encoded close in time. Using in vivo calcium imaging (with open-source Miniscopes in freely behaving mice), TetTag transgenic system, chemogenetics, electrophysiology and novel behavioral designs, we tested how hippocampal networks temporally link memories. Multiple convergent findings suggest that contextual memories encoded close in time are linked by directing storage into overlapping hippocampal ensembles, such that the recall of one memory can trigger the recall of another temporally-related memory. Alteration of this process (e.g. during aging, PTSD, etc) affect the temporal structure of memories, thus impairing efficient recall of related information. Tristan Shuman: Breakdown of spatial coding and interneuron synchronization in epileptic mice Temporal lobe epilepsy causes severe cognitive deficits yet the circuit mechanisms that alter cognition remain unknown. We hypothesized that the death and reorganization of inhibitory connections during epileptogenesis may disrupt synchrony of hippocampal inhibition. To test this, we simultaneously recorded from CA1 and dentate gyrus (DG) in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between CA1 and DG in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit using a novel wire-free Miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This place cell instability emerged ~6 weeks after status epilepticus, well after the onset of chronic spontaneous seizures and interneuron death. Finally, our CA1 network model showed that desynchronized inputs can impair information content and stability of CA1 place cells. Together, these results demonstrate that temporally precise intra-hippocampal communication is critical for spatial processing and hippocampal desynchronization contributes to spatial coding deficits in epileptic mice.

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Imaging deep: sensory and state coding in subcortical circuits

Date:

09

Thursday

January

2020

Lecture / Seminar

Time: 11:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Jan Grundemann

Organizer: Department of Brain Sciences

Details: Host: Dr. Yaniv Ziv yaniv.ziv@weizmann.ac.il tel: 4275 For assistance with ... Read more

Abstract: Internal states, including affective or homeostatic states, are important behavi ... Read more Internal states, including affective or homeostatic states, are important behavioral motivators. The amygdala is a key regulator of motivated behaviors, yet how distinct internal states are represented in amygdala circuits is unknown. Here, by longitudinally imaging neural calcium dynamics across different environments in freely moving mice, we identify changes in the activity levels of two major, non-overlapping populations of principal neurons in the basal amygdala (BA) that predict switches between exploratory and non-exploratory (defensive, anxiety-like) states. Moreover, the amygdala broadcasts state information via several output pathways to larger brain networks, and sensory responses in BA occur independently of behavioral state encoding. Thus, the brain processes external stimuli and internal states orthogonally, which may facilitate rapid and flexible selection of appropriate, state-dependent behavioral responses.

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Intricate Assembly Mechanism of Mucin Glycoproteins Revealed by Cryo-electron Microscopy of Polymers

Date:

31

Tuesday

December

2019

Lecture / Seminar

Time: 14:30-15:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Gabriel Javitt

Organizer: Department of Chemical and Structural Biology

Physical Genomics Harnessing physics and chemistry for single-molecule analysis of the human genome

Date:

30

Monday

December

2019

Lecture / Seminar

Time: 14:15

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Yuval Ebenstein, TAU

Organizer: Department of Physics of Complex Systems

Contact: perla.zalcberg@weizmann.ac.il

Abstract: DNA is an amazing memory device that holds the operating system of life. However ... Read more DNA is an amazing memory device that holds the operating system of life. However, DNA sequencing fails to extract the full range of information associated with genetic material and is lacking in its ability to resolve variations between genomes. As a consequence, many genomic features remain poorly characterized in the human genome reference. In addition, the information content of the genome extends beyond the base sequence in the form of chemical modifications such as DNA methylation or DNA damage lesions that chemically encode our life experiences in our DNA. By applying experimental principles of single molecule detection we gain access to the structural variation and long range patterns of genetic and epigenetic information. We show how physical extension of long DNA molecules on surfaces and in nanofluidic channels reveals such information in the form of a linear, optical “barcode” showing distinct types of observables. Recent results from our lab demonstrate our ability to detect epigenetic marks and various forms of DNA damage on individual genomic DNA molecules and use this information for medical diagnostics.

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Hyperactive FOXA1 Signaling in Breast Cancer Endocrine Resistance and Metastasis - When Genomics Meet Epigenomics

Date:

26

Thursday

December

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Max and Lillian Candiotty Building

Lecturer: Dr. Rachel Schiff

Organizer: Department of Biological Regulation

Contact: yam.nof@weizmann.ac.il

The Large Synoptic Survey Telescope: Status Update and Prospects for Science

Date:

26

Thursday

December

2019

Colloquium

Time: 11:15-12:30

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Steven M. Kahn

Organizer: Faculty of Physics

Details: 11:00 - Coffee, Tae and more

Abstract: The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field groun ... Read more The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field ground-based telescope designed to provide a time-domain imaging survey of the entire southern hemisphere of sky in six optical colors (ugrizy). Over ten years, LSST will obtain ~ 1,000 exposures of every part of the southern sky, enabling a wide-variety of distinct scientific investigations, ranging from studies of small moving bodies in the solar system, to constraints on the structure and evolution of the Universe as a whole. The development of LSST is a collaboration between the US National Science Foundation, which is supporting the development of the telescope and data system, and the US Department of Energy, which is supporting the development of the 3.2 gigapixel camera, the largest digital camera ever fabricated for astronomy. Approved in 2014, LSST is now well into construction, and is on track to beginning operations in 2022. I will review the design and technical status of the Project, and provide an overview of some of the exciting science highlights that we expect to come from this facility.

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Simulating the whole of magnetic resonance

Date:

19

Thursday

December

2019

Lecture / Seminar

Time: 09:30-10:30

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Ilia Kuprov

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: In a couple of years from now, we will finish kernel programming for Spinach – ... Read more In a couple of years from now, we will finish kernel programming for Spinach – a spin dynamics simulation library that supports all types of magnetic resonance spectroscopy, from Gd3+ DEER, through DNP and NMR, and all the way to singlet state diffusion MRI, including chemical kinetics, optimal control, and advanced relaxation theories. This level of generality hinges on: 1. The ability to treat classical degrees of freedom (diffusion, hydrodynamics, radiofrequency and microwave phases, stochastic tumbling, etc.) at the same conceptual level as spin degrees of freedom – the corresponding classical equations of motion must be integrated into the density matrix formalism. 2. The ability to survive enormous Kronecker products. A well digitised medical phantom would have at least a hundred points in each of the three directions, meaning a dimension of at least 1003 = 106 for the spatial dynamics generator matrices. At the same time, a typical radical contains upwards of ten coupled spins, meaning a Liouville space dimension of at least 410. Direct products of spin and spatial dynamics generators would then have the dimension in excess of 1012 even before chemical kinetics is considered. 3. Code parallelisation over cluster architectures, including the possibility of using a GPU on each node of the cluster. The principal problem is parallelisation mode switching between powder averages, indirect dimensions of pulse sequences, frequency points of frequency domain simulations, etc. – each simulation type would in general require a different mode of parallelisation and GPU utilisation. This report is about solving all of this, and on where the dark art of simulating a time-domain magnetic resonance experiment stands at the moment. Two recent innovations are the abandonment of Liouville equation in favour of Fokker-Planck equation as the core formalism, and the use of tensor structured objects that never open Kronecker products. A separate story is recent GPUs: NVidia Tesla V100 performs ~1013 double-precision multiplications per second – an astounding amount of computing power that is surprisingly easy to use.

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Decipher the properties of sex-shared yet dimorphic neuronal circuits

Date:

18

Wednesday

December

2019

Lecture / Seminar

Time: 15:15

Location: The David Lopatie Hall of Graduate Studies

Lecturer: Vladyslava Pechuk (MSc Thesis Defense/PhD Proposal)

Organizer: Department of Brain Sciences

Abstract: The nervous system of sexually reproducing species is built to accommodate their ... Read more The nervous system of sexually reproducing species is built to accommodate their sex-specific needs and thus contains sexually dimorphic properties. Males and females respond to environmental sensory cues and transform the input into sexually dimorphic traits. New findings reveal a significant difference in the way the two sexes in the nematode C. elegans respond to aversive stimuli. Further analysis of the function of the circuit for aversive behaviors unveiled how stimuli elicit non-dimorphic sensory neuronal activity, proceeded by dimorphic postsynaptic interneuron activity, generating the sexually dimorphic behavior. Here, we propose to uncover how genetic sex defines the properties of the sex-shared circuit for aversive behaviors. We will explore the circuit at the behavioral, connectome and genetic levels. Using calcium imaging, optogenetics, synaptic trans-labeling, transcriptome profiling and a candidate gene approach we will map the functional connections and define the dimorphic responses of all the cells in the avoidance circuit in both sexes. Since in vertebrates and invertebrates, males and females share most of the nervous system, studies of the development of dimorphic aspects of the shared nervous system are crucial for understanding the effects of sex on brain and behavior and specifically, how do changes in connectivity generate dimorphic behaviors, and how both are modulated by the genetic sex.

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At the Interface between Organic and Inorganic Matter: Interactions and Design of Simple Functional Coatings

Date:

18

Wednesday

December

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Meital Reches

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Several natural processes are mediated by the interactions between organic and ... Read more Several natural processes are mediated by the interactions between organic and inorganic materials. The immune response towards an implant inserted into the body is mediated by proteins. Composite materials are formed by the interactions of organic materials (usually proteins) and minerals. Biofouling, the process in which organisms attached to surfaces, is also mediated by organic molecules. Understanding the nature of interactions between organic and inorganic materials will bring to the development of improved implants, new composites and antifouling materials. This lecture will present single-molecule force spectroscopy measurements of the interactions between individual biomolecules (either amino acid residues or short peptides) and inorganic surfaces in aqueous solution. Using this method, we were able to measure low adhesion forces and could clearly determine the strength of interactions between individual amino acid residues and inorganic substrates. Our results with peptides also shed light on the factors that control the interactions at the organic-inorganic interface. Based on our knowledge from single molecule experiments, we designed a short peptide (tripeptide) that can spontaneously form a coating that resists biofilm formation. Our results clearly demonstrate the formation of a coating on various surfaces (glass, titanium, silicon oxide, metals and polymers). This coating prevents the first step of antifouling, which involves the adsorption of bioorganic molecules to the substrate. In addition, it significantly reduces the attachment of various organisms such as bacteria and fungi to surfaces. Another variation of this peptide can encourage the adhesion of mammalian cells while preventing biofilm formation.

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In vivo multimodality imaging of immune-vascular interactions in cardiovascular disease

Date:

12

Thursday

December

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Katrien Vandoorne

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Cardiovascular disease is a result of genetic and environmental risk factors tha ... Read more Cardiovascular disease is a result of genetic and environmental risk factors that together generate arterial and cardiac pathologies. Blood vessels connect multiple organ systems throughout the entire body allowing organs to interact via circulating messengers. Multimodality imaging achieves integration of these interfacing systems’ distinct processes, quantifying interactions that contribute to cardiovascular disease. Noninvasive multimodality imaging techniques are emerging tools that can further our understanding of this complex and dynamic interplay. Multichannel multimodality imaging including optics, CT, PET and MRI, are particularly promising because they can simultaneously sample multiple biomarkers. As the opportunities provided by imaging expand, mapping interconnected systems will help us decipher the complexity of cardiovascular disease and monitor novel therapeutic strategies.

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Spatial Transcriptomics: A getting started guide to the 10x genomics Visium Spatial Gene expression Solution

Date:

03

Tuesday

December

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Nicola Cahill

Organizer: Department of Life Sciences Core Facilities

Contact: Hadas.Keren-Shaul@weizmann.ac.il

Abstract: The Visium Spatial Gene Expression Solution from 10x Genomics analyzes complete ... Read more The Visium Spatial Gene Expression Solution from 10x Genomics analyzes complete transcriptomes in intact tissue sections, allowing you to discover genes and markers relevant to your research without having to rely on known targets. Preserving spatial resolution offers critical information for understanding the relationships between cellular function, phenotype, and location in the tissue.

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Attosecond Interferometry

Date:

28

Thursday

November

2019

Colloquium

Time: 11:15-12:30

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Nirit Dudovich

Organizer: Faculty of Physics

Details: 11:00 Coffee, Tae and more

Abstract: Attosecond science is a young field of research that has rapidly evolved over th ... Read more Attosecond science is a young field of research that has rapidly evolved over the past decade. The progress in this field opened a door into a new area of research that allows one to observe multi-electron dynamics in atoms, molecules and solids. One of the most important aspect of attosecond spectroscopy lies in its coherent nature. Resolving the internal coherence is a primary challenge in this field, serving as a key step in our ability to reconstruct the internal dynamics. As in many other branches in physics, coherence is resolved via interferometry. In this talk, I will describe advanced schemes for attosecond interferometry. The application of these schemes provides direct insights into a range of fundamental phenomena in nature, from tunneling and photoionization in atomic systems to ultrafast chiral phenomena in molecules.

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Preclinical Imaging using Electron Paramagnetic Resonance

Date:

28

Thursday

November

2019

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Boris Epel

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Electron Paramagnetic Resonance (EPR) Imaging is a well-established method for t ... Read more Electron Paramagnetic Resonance (EPR) Imaging is a well-established method for the study of spatial distribution and local environment of electron paramagnetic centers and spin probes. One of the most important applications of modern EPR imaging is in vivo oximetry in which soluble spin probes with oxygen-dependent relaxation rates are used. Partial oxygen pressure (pO2) levels in tumors are major determinants of the response to cancer therapy. I will present the results of the in vivo oxygen guided radiation targeting study. This study combines pO2 images and conformal radiation delivery using 3D-printed blocks to achieve high precision treatment of tumor hypoxic areas. The study demonstrates that the dose to well-oxygenated tumor volumes in fibrosarcoma tumors in mice can be considerably reduced without compromising the outcome.

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Application of Electron Crystallography Methods in Metallurgy

Date:

20

Wednesday

November

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Louisa Meshi

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Due to the direct correlation among the physical properties and crystal structur ... Read more Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.

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Dynamic functional organization of midbrain dopamine neurons during complex behavior

Date:

19

Tuesday

November

2019

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Ben Engelhard

Organizer: Department of Brain Sciences

Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance w ... Read more

Abstract: Dopamine is an essential neurotransmitter in brain that has been implicated in m ... Read more Dopamine is an essential neurotransmitter in brain that has been implicated in many devastating brain conditions and associated behavioral deficits, including working memory deficits in Parkinson's disease, motivational deficits in schizophrenia, attention deficits in ADHD and more. However, in contrast to the variety of functions clinically attributed to dopamine, the neurobiological literature has considered dopamine neurons to be mainly involved in reward processing, raising the question of how a diverse array of functions can be accounted for by such a limited behavioral role. The involvement of ventral tegmental area (VTA) dopamine neurons in reward processing and learning has been firmly shown using Pavlovian conditioning or simple cue-reward association behaviors; in those experiments, dopamine neurons behaved as a functionally homogenous population dopamine activity in more complex behaviors has been less well studied, mainly due to technical difficulties of monitoring large ensembles of genetically identified dopamine neurons during complex behavior. To overcome this gap, we performed new experiments of dopamine function by combining a novel technique for studying VTA dopamine neurons (2-photon calcium imaging via a GRIN lens) with a complex behavioral assay (navigation-based decision making in virtual reality). We show that during complex behavior, dopamine neurons divide into distinct, anatomically organized, functional subpopulations that mediate different aspects of the behavior (Engelhard et al., Nature 2019). This newfound functional diversity of dopamine neurons offers a novel view of the behavioral role of dopamine: rather than consisting of a single functional block, dopamine neurons may flexibly encode a diverse array of behavioral variables via distinct functional subpopulations that emerge in response to behavioral demands.

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Application of Electron Crystallography Methods in Metallurgy

Date:

13

Wednesday

November

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Louisa Meshi

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Due to the direct correlation among the physical properties and crystal structur ... Read more Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.

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Transmission Electron Microscopy in Motion

Date:

03

Sunday

November

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Frances M. Ross

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: We can watch crystals grow in the electron microscope by adding atoms one at a t ... Read more We can watch crystals grow in the electron microscope by adding atoms one at a time onto a clean surface. The movies tell us about kinetics and thermodynamics but can also be entertaining, frustrating, or both at the same time. I will attempt to share the joy of this type of “in situ” microscopy as we aim to understand how atoms assemble into nanowires or nanocrystals and use the information to control the formation of more complicated nanostructures with new properties

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Characterization of Biomolecule and Structure Changes using Polarization Transfer from Hyperpolarized Water

Date:

31

Thursday

October

2019

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Jihyun Kim

Organizer: Department of Molecular Chemistry and Materials Science

Mini-Symposium on Demystifying machine learning for microscopy Conference website

Abstract: Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool for ... Read more Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool for the characterization of protein structure and intermolecular interactions. However, NMR is not readily applicable to determine fast structural changes and weak interactions between molecules because of low signal sensitivity and time requirements to record multi-dimensional NMR spectra. To overcome these limits, the hyperpolarization technique of dissolution dynamic nuclear polarization (D-DNP) is combined with NMR. Not all molecules can be directly hyperpolarized. Instead, polarization transfer from hyperpolarized small molecules to a target of interest can be utilized as a means of obtaining polarization, as well as for detecting intermolecular interactions between these molecules Here, hyperpolarized water-assisted NMR spectroscopy was developed to measure intermolecular interactions with water. Firstly, the use of DNP hyperpolarization was demonstrated for the accurate determination of intermolecular cross-relaxation rates between hyperpolarized water and fluorinated target molecules.[1] Because hyperpolarized water acts as a source spin with a large deviation of the population from the equilibrium, the 19F signal on the target molecules is enhanced through NOE, allowing obtain an entire NOE buildup curve in a single, rapid measurement. When the hyperpolarized water-assisted NMR experiment is applied to a protein, water hyperpolarization can be transferred to amide protons on the protein through proton exchange. Further, this polarization spreads within the protein through intramolecular NOE to nearby protons including aliphatic groups.[2] By utilizing this polarization transfer, this method extends to measure enhanced 2D NMR spectra of the protein under folded and refolding conditions.[3] With the ability to rapidly measure protein signals that were enhanced through transferred polarization from hyperpolarized water, NMR spectra can be acquired within the timescale of the protein folding. Compared to the folded protein experiment, signals attributed to exchange-relayed NOEs are not observable in the refolding experiment (Figure 1b). These differences are explained by the absence of long-range contacts with nearby exchangeable protons such as OH protons

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Mini-Symposium on Demystifying machine learning for microscopy

Date:

31

Thursday

October

2019

Conference

Time: 08:00

Location: David Lopatie Conference Centre

Contact: ofra.golani@weizmann.ac.il

Molecular Electron Microscopy for Studies on Mechanism of Molecular Motions and Reactions

Date:

28

Monday

October

2019

Colloquium

Time: 11:00-12:15

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Eiichi Nakamura

Organizer: Faculty of Chemistry

Life Science Lectures- Recovering lost information: potential applications in biomedical research

Date:

03

Thursday

October

2019

Lecture / Seminar

Time: 10:00-11:30

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Yonina Eldar

Organizer: Life Sciences

Contact: ela.ulman@weizmann.ac.il

Details: Benoziyo Biochemistry Auditorium, room 191c Light refreshment will be served at ... Read more

Abstract: The conversion of physical analog signals to the digital domain for further proc ... Read more The conversion of physical analog signals to the digital domain for further processing inevitably entails loss of information. In many modern applications, the signal bandwidths have increased tremendously, while the acquisition capabilities have not scaled sufficiently fast. Furthermore, the resulting high rate digital data requires storage, communication and processing at very high rates which is computationally expensive and requires large amounts of power. In the context of medical imaging sampling at high rates often translates to high radiation dosages, increased scanning times, bulky medical devices, and limited resolution. In this talk, we present a framework for sampling and processing a wide class of wideband analog signals at rates far below the standard Nyquist rate, by exploiting signal structure and the processing task and show several demos of real-time sub-Nyquist prototypes. We consider applications of these ideas to a variety of problems including fast and quantitative MRI, wireless ultrasound, and super-resolution in microscopy and ultrasound which combines high spatial resolution with short integration time. We then show how the ideas of exploiting the task, structure and model can be used to develop interpretable model-based deep learning methods that can adapt to existing structure and are trained from small amounts of data.

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Chemical and Biological Physics Guest Seminar

Date:

24

Tuesday

September

2019

Lecture / Seminar

Time: 11:00

Title: Probing Reactions at Electrochemical and Catalytic Interfaces with X-ray Spectroscopies

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Robert Weatherup

Organizer: Department of Chemical and Biological Physics

Contact: baran.eren@weizmann.ac.il

Abstract: Probing the chemical reactions occurring at electrochemical and catalytic interf ... Read more Probing the chemical reactions occurring at electrochemical and catalytic interfaces under realistic conditions is critical to selecting and designing improved materials for energy storage, corrosion prevention, and chemical production. Soft X-ray spectroscopies offer powerful element- and chemical-state-specific information with the required nm-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of interfaces under realistic liquid- and gas-phase environments.1 Here we introduce several membrane-based approaches developed in recent years in order to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid and solid-gas interfaces at atmospheric pressures.2–5 These rely on reaction cells sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber.2,3 Thin (

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Chemical and Biological Physics Dept Special Seminar

Date:

15

Sunday

September

2019

Lecture / Seminar

Time: 11:00

Title: Single-Molecule Spectroscopy with Catalysts, Conductive Polymers, and Optical Microresonators

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Randall Goldsmith

Organizer: Department of Chemical and Biological Physics

Contact: gilad.haran@weizmann.ac.il

Applications of Hadamard Transform in NMR Spectroscopy

Date:

09

Monday

September

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Eriks Kupce

Organizer: Department of Molecular Chemistry and Materials Science

Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM

Date:

05

Thursday

September

2019

Lecture / Seminar

Time: 10:30

Location: Perlman Chemical Sciences Building

Lecturer: Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM

Organizer: Department of Chemical Research Support

Enhanced single-molecule imaging through mechanistic analysis of blinking and point-spread function engineering?

Date:

09

Tuesday

July

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Peter Dedecker

Organizer: Department of Chemical and Structural Biology

Measuring nanometre distances in biomolecules using EPR Spectroscopy

Date:

27

Thursday

June

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Janet Lovett

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: EPR spectroscopy can be used to measure nanometre-scale distances within biomole ... Read more EPR spectroscopy can be used to measure nanometre-scale distances within biomolecules and other soft matter, through determining the dipolar coupling between paramagnetic centres. These can be placed site-specifically within the molecules-of-interest as spin labels. Some experiments that measure the dipolar coupling will be introduced, and results including new spin labels and applications of the methodology will be discussed.

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Methods and Problems in BioImaging Workshop

Date:

24

Monday

June

2019

Conference

Time: 08:00-18:00

Location: David Lopatie Conference Centre

Contact: ofra.golani@weizmann.ac.il

Single and multi-frequency saturation methods for molecular and microstructural contrast in human MRI”

Date:

20

Thursday

June

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Elena Vinogradov

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Magnetic Resonance Imaging (MRI) provides excellent quality images of soft tissu ... Read more Magnetic Resonance Imaging (MRI) provides excellent quality images of soft tissues and is an established modality for diagnosis, prognosis and monitoring of various diseases. Majority of MRI scans in clinical practice today report on anatomy, morphology and sometimes physiology. The new area of active studies is aimed at developing MRI contrast methods for the detection of the events at the microstructural and molecular level employing endogenous properties. Here, we will discuss methods that employ single- and multi-frequency saturation to detect events on microstructural and molecular level. First, we will describe principles and translational aspects of Chemical Exchange Saturation Transfer1(CEST). CEST employs selective saturation of the exchanging protons and subsequent detection of the water signal decrease to create images that are weighted by the presence of a metabolite or pH2. We will describe aspects of translating CEST to reliable clinical applications and discuss its potential uses in human oncology, specifically breast cancer. Second, we will describe a method called inhomogeneous Magnetization Transfer3 (ihMT), which employs dual-frequency saturation to create contrast originating from the residual dipolar couplings and thus specific to microstructure. We will focus on the application of ihMT to the detection of myelin in brain and spinal cord. Finally, we will discuss a novel exchange-sensitive method based on the balanced steady-state free precession (bSSFP) sequence as an alternative way for chemical exchange detection (bSSFPX4). Using an effective field description, similarities between bSSFP and CW application can be explored and utilized for in-vivo MRI contrast. [1] K. Ward, et.al., JMR,143,79-87 (2000). [2] J. Zhou, et.al., Nature Medicine, 9,1085-1090 (2003). [3] G. Varma, et.al., MRM, 73, 614-622 (2015). [4] S. Zhang, et.al., JMR, 275, 55-67 (2017).

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Brain control and readout at biologically relevant resolutions

Date:

17

Monday

June

2019

Lecture / Seminar

Time: 11:00

Location: Max and Lillian Candiotty Building

Lecturer: Dr. Or Shemesh

Organizer: Department of Brain Sciences

Details: Host: Prof. Rony Paz rony.paz@weizmann.ac.il tel: 6236 For assistance with acc ... Read more

Abstract: Understanding the neural basis of behavior requires studying the activity of neu ... Read more Understanding the neural basis of behavior requires studying the activity of neural networks. Within a neural network, single neurons can have different firing properties, different neural codes and different synaptic counterparts. Therefore, it will be useful to readout from the brain and control it at a single-cell resolution. However, until recently, single cell readout and control in the brain were not feasible. The first scientific problem we addressed, is this regard, was the low spatial resolution of light based neural activation. Opsins are genetically encoded light switches for neurons that cause neural firing, or inhibition, when illuminated (and are therefore called “opto-genetic” molecules). However, optogenetic experiments are biased by ‘crosstalk’: the accidental stimulation of dozens of cells other than the cell of interest during neuron photostimulation. This is caused by expression of optogenetic molecules through the entirety of the cells, from the round cell body (“soma”) to the elongated neural processes. Our solution was molecular-focusing: by limiting the powerful opsin CoChR to the cell body of the neuron, we discovered that we could excite the cell body of interest alone. This molecule, termed “somatic-CoChR” was stimulated with state of the art holographic stimulation to enable millisecond temporal control which can emulate actual brain activity. Thus, we achieved for the first time single cell optogenteic stimulation at sub millisecond temporal precision. A second challenge was imaging the activity of multiple cells at a single cell resolution. The most popular neural activity indicator is the genetically encoded calcium sensor GCaMP, due to its optical brightness and high sensitivity. However, the fluorescent signal originating from a cell body is contaminated with multiple other fluorescent signals that originate from neurites of neighboring cells. This leads to a variety of artifacts including non-physiological correlation between cells and an impaired ability to distinguish between signals coming from different cells. To solve this, we made a cell body-targeted GCaMP. We screened over 30 different targeting motifs for somatic localization of GCaMP, and termed the best one, in terms of somatic localization, “SomaGCaMP”. This molecule was tested in live mice and zebrafish and can report the activity of thousands of neurons at a single cell resolution. A third challenge was voltage imaging in the brain, since genetically encoded indicators still suffered from either low sensitivity, or from low brightness. To record voltage, we used nitrogen vacancy nanodiamonds, known to be both very bright and sensitive to electric fields. Our aim was to bring the nanodiamonds to the membrane so the large electric field created by the action potential could impinge upon them and change their fluorescence. By making the nanodiamonds hydrophobic through surface chemistry modification, and inserting them into micelles, we labeled neural membranes with monodisperse diamonds for hours. We are now in the process of assessing the sensitivity of the nanodiamonds to the membrane voltage. Altogether, thinking backwards from fundamental limitations in neuroscience is instrumental in deriving strategies to fix these limitations and study the brain. In the future, we will use similar approaches to study and heal brain disease, at single-cell and subcellular resolutions.

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Design and validation of a head coil for MRI at 7T

Date:

12

Wednesday

June

2019

Lecture / Seminar

Time: 15:00-16:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Shajan Gunamony

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Radio frequency (RF) coil design for ultra-high field MRI scanners is an active ... Read more Radio frequency (RF) coil design for ultra-high field MRI scanners is an active field of research. We have recently developed an 8-channel transmit, 32-channel receive 7T head coil at the University of Glasgow. We focused on an open-faced design to make the setup less claustrophobic and more acceptable in a clinical environment. Furthermore, the coil can be used in both the scanner modes. I will also present our internal validation process which allows home-built RF coils to be used in vivo.

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Finding a Needle: Correlative Light and Volume EM Approach to Resolve Vesicular Fusion

Date:

28

Tuesday

May

2019

Lecture / Seminar

Time: 10:15-10:30

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Nadav Scher

Organizer: Department of Biomolecular Sciences

Abstract: Most biological phenomena must be studied across scales, ranging from entire org ... Read more Most biological phenomena must be studied across scales, ranging from entire organisms to molecules in cells. However, bridging these scales can often be challenging, especially if dynamic changes in protein composition must be examined together with changes in cellular organization and ultrastructure. To overcome these challenges, we are developing an imaging approach harnessing the strengths of fluorescence microscopy and large volume electron microscopy, which can be achieved with a focused ion beam scanning electron microscope (FIB/SEM). In my talk, I will present the state-of-the-art in our correlative light and volume electron microscopy workflow and demonstrate its application for the study of secretion in the fruit fly’s salivary gland.

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Revealing the dynamic stability of fusion pores in giant vesicles through live, super-resolution microscopy

Date:

28

Tuesday

May

2019

Lecture / Seminar

Time: 10:00-10:15

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Tom Biton

Organizer: Department of Biomolecular Sciences

Abstract: Exocytosis occurs in all living cells and is essential for many cellular process ... Read more Exocytosis occurs in all living cells and is essential for many cellular processes including metabolism, signaling, and trafficking. During exocytosis, cargo loaded vesicles dock and fuse with the plasma membrane to release their content. To accommodate different cargos and cellular needs exocytosis must occur across scales; From synaptic vesicles that are only ~50nm in diameter, and neuroendocrine vesicles that are in the ~500nm range to giant secretory vesicles filled with viscous cargo, such as in the acinar cells in the exocrine pancreas, that reach up to a few µm in diameter. Yet, how fusion and content release are adapted to remain function across these scales is not well understood. It is well established that during exocytosis of small vesicles, vesicle fusion can proceed through one of two pathways: The first is complete incorporation, when the vesicular membrane fuses to the target membrane and the fusion pore expand irreversibly, incorporating the vesicular membrane into the target membrane. The second is “kiss-and-run”, when the fusion pore flickers, opening briefly and collapsing rapidly into two separate membranes. I am interested in understanding how exocytosis occurs in giant vesicles witch challenge efficient secretion and membrane homeostasis due to their massive size and viscous content. I am using the salivary gland of D. Melanogaster, as a model system for giant vesicles secretion. The vesicles in the gland measure between 5-8 µm, fuse and secrete viscous content into a preformed lumen. To visualize the secretion process, I adapted a method for super-resolution microscopy to live-gland imaging. I observed that fusion pores of giant vesicles expand to a stable opening of up to 3µm and slowly constricts down to hundreds of nm or less during secretion. Because constricting a membrane pore from “infinity” in molecular terms, back to a very narrow ‘stalk’ demands an investment of energy, I hypothesized that this is mediated by a specialized protein machinery. I am currently screening for the components of the machinery using the enormous power of Drosophila genetics by taking a candidate gene approach. My preliminary results identify the BAR domain containing protein, MIM (missing in metastasis) as a key regulator of pore dynamics, leading to new and exciting insights into the molecular mechanism of cellular secretion and membrane homeostasis in live tissues.

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Life Science Lectures - Emerging imaging technologies to study cell architecture, dynamics and function

Date:

27

Monday

May

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Dr. Jennifer Lippincott-Schwartz

Organizer: Life Sciences

Contact: ela.ulman@weizmann.ac.il

Details: Host : Prof. Zvulun Elazar Light refreshments will be served at 13:40 in the lobby

Imaging the human brain: ultra-high field MRI and new biomarkers

Date:

26

Sunday

May

2019

Lecture / Seminar

Time: 13:00

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Rita Schmidt

Organizer: Department of Physics of Complex Systems

Contact: perla.zalcberg@weizmann.ac.il

Abstract: Times New Roman (Headings CS) ... Read more

Departmental Seminar

Date:

26

Sunday

May

2019

Lecture / Seminar

Time: 13:00-14:00

Title: Developing a highly sensitive CRISPR based platform for virus and host functional genomics

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Yaara Finkel

Organizer: Department of Molecular Genetics

Contact: evi@weizmann.ac.il

CRASH COURSE ON GENOMICS and BIOINFORMATICS OF CANCER

Date:

18

Thursday

April

2019

Lecture / Seminar

Time: 11:45-14:00

Location: Max and Lillian Candiotty Building

Lecturer: Prof. Eytan Ruppin, Prof. Itay Tirosh

Organizer: Department of Biomolecular Sciences

Contact: tamar.cohen@weizmann.ac.il

The mechanics of malaria parasite invasion of the red cell (and beyond): seeking a balanced view of parasite-host contributions to entry

Date:

16

Tuesday

April

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Jacob Baum

Organizer: Department of Biomolecular Sciences

Abstract: Entry of the malaria parasite merozoite, the micron sized cell responsible for b ... Read more Entry of the malaria parasite merozoite, the micron sized cell responsible for blood-stage malaria infection, into the human red blood cell defines establishment of malaria disease. The process is rapid yet contains a great depth of cell biology, one eukaryotic cell actively penetrating the other. Entry has long been seen as a very parasite-centric process with the merozoite literally driving its way into a passive erythrocyte. This is in marked contrast to other pathogens that utilise host-cell phagocytosis to gain entry to human cells. Has this inbalanced view been over-stated in the case of the merozoite? Recent data from several groups suggests that erythrocyte biophysics (including membrane biophysical properties) also contributes to the process of merozoite entry. Here, I will present our latest insights into the role of both parasite and host cell factors and how they might be contributing to lowering the energy barrier required to get the merozoite inside the human red blood cell. With a particular focus on cell imaging, I will present our vision of invasion being a balanced equation with parasite motor force and host membrane deformability both contributing to allow the blood-stage malaria parasite (and may be beyond the blood stages) get in.

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Advanced Electron Microscopy Symposium

Date:

10

Wednesday

April

2019

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11

Thursday

April

2019

Conference

Time: 08:00

Location: David Lopatie Conference Centre

Organizer: Department of Chemical Research Support

Contact: sharon.wolf@weizmann.ac.il

Growth mechanisms of quasi-1D semiconductors and oxides deduced from real-time electron microscopy

Date:

08

Monday

April

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Kolibal Miroslav

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: One-dimensional materials represent an attractive class of nanostructures, mainl ... Read more One-dimensional materials represent an attractive class of nanostructures, mainly because of their geometry which inherently implies applications such as electrodes for sensing purposes or conduction channels in nanoscale electronics. Different mechanisms may be utilized to prepare nanowires, e.g. stress-driven one-dimensional diffusion, metal-catalyzed growth (VLS) etc. The most important role in identifying and description of the growth mechanisms is played by real-time microscopies, mostly TEM. However, although very powerfull in terms of image resolution, TEM is also limited in use, especially because of very strict sample geometry requirements. In this seminar talk, I will present our real-time in-situ scanning electron microscopy experiments of nanowire growth. Two different material systems will be presented – germanium nanowires catalyzed by Au nanoparticles and WOx nanowires. As for the latter case, our experiments reveal a very unusual oxidation mechanism of tungsten disulfide nanotubes, resulting in tungsten oxide nanowire formation. The talk will summarize studies on quasi-1D systems conducted at IPE and CEITEC BUT.

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Metal oxide growth within block copolymers – mechanism, challenges and opportunities

Date:

07

Sunday

April

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Tamar Segal-Peretz

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Self-assembly of block copolymers (BCP) is a well-known method for nanostructure ... Read more Self-assembly of block copolymers (BCP) is a well-known method for nanostructure fabrication at the 5-50 nm scale. Recently, sequential infiltration synthesis (SIS) was developed from atomic layer deposition (ALD) chemistry for selective growth of inorganic materials within polymers. In this talk, I will discuss SIS mechanism and growth process development as well as our work on combining BCP self-assembly with SIS for nanoparticle structuring, 3D imaging with TEM tomography, ultrafiltration membranes, and advanced 3D nanofabrication.

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Optics in the Air

Date:

03

Wednesday

April

2019

Lecture / Seminar

Time: 14:00

Location: Sussman Family Building for Environmental Sciences

Lecturer: Joseph Shaw

Organizer: Department of Earth and Planetary Sciences

Abstract: This talk will use photographs and diagrams to illustrate and explain some of th ... Read more This talk will use photographs and diagrams to illustrate and explain some of the beautiful optical phenomena observable in nature, such as ice‐crystal halos, rainbows, and sky colors, and will relate them to ongoing research into the spectral and spatial distribution of polarization in the atmosphere. Our group at Montana State University has pioneered all‐sky imaging methods to study skylight polarization and relate it to properties of airborne particles, clouds, and the underlying surface. Brief results from a deployment of all‐sky polarization imagers at the August 2017 solar eclipse will be shown and related to a more general discussion of atmospheric optical effects that can be seen by eye. The talk takes its title from my 2017 book, which describes optical phenomena in nature, especially as seen through airplane windows.

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Imaging phase transitions with scanning SQUID

Date:

01

Monday

April

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Beena Kalisky

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: We use a local magnetic imaging technique, scanning SQUID microscopy, to map t ... Read more We use a local magnetic imaging technique, scanning SQUID microscopy, to map the spatial distribution of electronic states near surfaces and interfaces. We track conductivity, superconductivity and magnetism in systems undergoing phase transitions, where the local picture is particularly meaningful. I will describe two measurements: At the superconductor-insulator transition in NbTiN we map superconducting fluctuations and detect a non-trivial behavior near the quantum critical point. Near the metal to insulator transition at the 2D LaAlO3/SrTiO3 interface, we find that the conduction landscape changes dramatically and identify the way different types of defects control the behavior.

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Molecules in Large and Small Pores as Observed by NMR Spectroscopy. Pore Structure, Tortuosity and Molecular Interactions

Date:

31

Sunday

March

2019

Lecture / Seminar

Time: 15:30-16:30

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Istvan Furo

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: The seminar summarizes three recent studies (1,2,3) since that share some comm ... Read more The seminar summarizes three recent studies (1,2,3) since that share some common elements: they concern porous materials and the method used is NMR spectroscopy. Yet, the aims differ. In the first study (1), the unknown is the pore structure. In particular, pore structure in hydrogels is difficult to access as water cannot be removed without affecting the pores and in the presence of water the well-honed gas sorption and mercury porosimetries just do not work. The method we invented to remedy this situation is called size-exclusion quantification (SEQ) NMR and it can be seen as the multiplexed analogue of inverse size exclusion chromatography. In effect, we sample by diffusion NMR the size distribution in a polydisperse polymer solution before and after it had been equilibrated with a porous matrix. Size-dependent polymer ingress reveals the pore structure. The method has several advantages over possible alternatives, not least its speed. In the second study (2), we sample the self-diffusion of neat water and other molecules like dimethyl sulfoxide (DMSO) and their mixtures by NMR diffusion experiments for those fluids imbibed into controlled pore glasses (CPG, pore size range 7.5 to 73 nm). Their highly interconnected structure is scaled by pore size and exhibits pore topology independent of size. Relative to the respective diffusion coefficients obtained in bulk phases, we observe a reduction in the diffusion coefficient that is independent of pore size for the larger pores and becomes stronger toward the smaller pores. Geometric tortuosity governs the behavior at larger pore sizes, while the interaction with pore walls becomes the dominant factor toward smaller pore diameters. Deviation from the trends predicted by the popular Renkin equation and variants (4) indicates that the interaction with the pore wall is not just a simple steric one. In the third study (3), the porous material is hydrated cellulose. In that matrix, we identify by using 2H MAS NMR two different groups of water molecules being in slow exchange with each other. Water molecules in one of the groups exhibit anisotropic molecular motions with a high order parameter. Based on, among other things, the observed behavior with increasing vapor pressure, we argue that this water is an integral structural element of the cellulose fibril, that itself is an aggregate of the basic units, the cellulose nanofibrils.

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The Lab on a Beam: From Learning Physics to Atomic Manipulation in Scanning Transmission Electron Microscopy

Date:

13

Wednesday

March

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Sergei Kalinin

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Atomically-resolved imaging of materials has become the mainstay of modern mater ... Read more Atomically-resolved imaging of materials has become the mainstay of modern materials science, as enabled by advent of aberration corrected scanning transmission electron microscopy (STEM). However, the wealth of quantitative information contained in the fine details of atomic structure or spectra remains largely unexplored. In this talk, I will present the new opportunities enabled by physics-informed big data and machine learning technologies to extract physical information from static and dynamic STEM images. The deep learning models trained on theoretically simulated images or labeled library data demonstrate extremely high efficiency in extracting atomic coordinates and trajectories, converting massive volumes of statistical and dynamic data into structural descriptors. I further present a method to take advantage of atomic-scale observations of chemical and structural fluctuations and use them to build a generative model (including near-neighbor interactions) that can be used to predict the phase diagram of the system in a finite temperature and composition space. Similar approach is applied to probe the kinetics of solid-state reactions on a single defect level and defect formation in solids via atomic-scale observations. Finally, synergy of deep learning image analytics and real-time feedback further allows harnessing beam-induced atomic and bond dynamics to enable direct atom-by-atom fabrication. Examples of direct atomic motion over mesoscopic distances, engineered doping at selected lattice site, and assembly of multiatomic structures will be demonstrated. These advances position STEM towards transition from purely imaging tool for atomic-scale laboratory of electronic, phonon, and quantum phenomena in atomically-engineered structures.

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Spectral editing techniques for chemical exchange saturation transfer imaging

Date:

12

Tuesday

March

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Jiadi Xu

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI tec ... Read more Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through water. CEST MRI is still under development and one major impediment for more widespread application is limited specificity due to spectral overlap of CEST signal from other metabolites and proteins. In this presentation, I will demonstrate several novel CEST spectral editing techniques developed by our group to extract information from CEST images, such as one variable delay multi pulse (VDMP) CEST that acts an exchange rate filter to separate CEST effects from the confounding factors, one ultra-short echo (UTE)-CEST method that can monitor in vivo protein aggregation process and one polynomial and Lorentzian line-shape fitting (PLOF) CEST that can detect creatine and phosphocreatine in tissue with high specialty. Their applications on the stroke and Alzheimer’s disease models will be covered. At last, I will explore one artificial neural network approach to overcome the challenges of implementing the CEST technique on 3T clinical MRI scanners.

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Pulsed Dipolar EPR Spectroscopy: From Model Systems to In-Cell

Date:

07

Thursday

March

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Olav Schiemann

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Understanding the function of biomolecules on a molecular level requires knowled ... Read more Understanding the function of biomolecules on a molecular level requires knowledge about their structure and conformational changes during function. Site directed spin labeling (SDSL) in combination with pulsed dipolar EPR spectroscopy (PDS) enables to gather such information on the nanometer length scale. In the talk, it will be shown that this approach enables the localization of metal ions within the fold of biomolecules, also of those metal ions with large zero-field splitting, where the high-field approximation breaks down. It will also be shown that this cannot only be done in vitro but also within cells. Last but not least, an example will be given where a conformational change of a protein is not only followed on the length- but also on the microsecond time resolution using PDS/SDSL.

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Mn(II) EPR tracks the hydrolysis state and ATP/ADP dependent conformation in yeast Hsp90 chaperone

Date:

28

Thursday

February

2019

Lecture / Seminar

Time: 14:00-15:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Angeliki Giannoulis

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Hsp90 plays a central role in cell homeostasis by assisting folding and maturati ... Read more Hsp90 plays a central role in cell homeostasis by assisting folding and maturation of many client proteins. In order to perform this chaperoning activity Hsp90 hydrolyzes ATP, which requires Mg(II) as cofactor and the hydrolysis is coupled to large global conformational changes. Hsp90 is homo-dimeric with each monomer consisting of three consecutive domains (CTD, MD, NTD). The ATPase site is found in each of the two NTDs, while the CTDs constitute the dimerization site. X-ray crystallography and FRET have provided insights on the conformational cycle of Hsp90 which involves transition from a nucleotide-free ‘open’ to a nucleotide-bound ‘closed’ conformation by dimerization of the NTDs. However, there are still open questions on whether the chaperone shifts global conformation as a consequence of hydrolysis. Here, we investigate the ATPase site and the concomitant conformational changes at various nucleotide-bound states (pre-hydrolysis, intermediate high energy and post- hydrolysis states) in yeast Hsp90 using EPR techniques. To do so, we substituted the Mg(II) cofactor with paramagnetic Mn(II) and performed hyperfine and pulsed dipolar EPR experiments, to probe short and long range interactions, respectively. Specifically, we tracked ATP hydrolysis by exploring the Mn(II) coordination by the nucleotide phosphates using 31P electron nuclear double resonance (ENDOR) spectroscopy. The interaction of the Mn(II) with protein residues in the different hydrolysis states was investigated by 14/15N ELDOR-detected nuclear magnetic resonance (EDNMR). Last, we measured the distance between the two Mn(II) cofactors in each of the monomers using double electron–electron resonance (DEER/PELDOR) spectroscopy. Here, we measured a well-defined Mn(II)-Mn(II) distance of 4.3 nm in the pre-hydrolysis state, which changes both in width and mean distance in the post-hydrolysis state providing experimental evidence to the existence of two different ‘closed’ conformations for the ATP and ADP bound states. Within our approach one can probe both local and global interactions from a single sample via exploitation of intrinsic sites (here Mg(II)->Mn(II)) that can potentially yield new structural insights previously challenging to observe with FRET and EPR using site-specific spin labeling.

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"DLTS defects characterization of process and irradiation induced defects in 4H-SiC”

Date:

28

Thursday

February

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Mmantsae Diale

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: 4H-SiC epitaxial layers were irradiated using various radioactive sources and pa ... Read more 4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.

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DLTS defects characterization of process and irradiation induced defects in 4H-SiC

Date:

28

Thursday

February

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Mmantsae Diale

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: 4H-SiC epitaxial layers were irradiated using various radioactive sources and pa ... Read more 4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.

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Diamond quantum technologies: magnetic sensing, hyperpolarization and noise spectroscopy

Date:

27

Wednesday

February

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Nir Bar-Gill

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as ... Read more Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as well-controlled quantum systems, with promising applications ranging from quantum information science to magnetic sensing. In this talk, I will first introduce the NV center system and the experimental methods used for measuring them and controlling their quantum spin dynamics. I will mention the application of magnetic sensing using NVs through the realization of a magnetic microscope [1]. I will then describe our work on nuclear hyperpolarization, potentially relevant for enhanced MRI contrast, and research into open quantum systems and quantum thermodynamics [2]. Finally, I will present related control sequences, which can be used to perform optimized quantum noise spectroscopy, allowing for precise characterization of the environment surrounding a quantum sensor [3]. 1. E. FARCHI ET. AL., SPIN 7, 1740015 (2017). 2. HOVAV, Y., NAYDENOV, B., JELEZKO, F. AND BAR-GILL, N., PHYS. REV. LETT. 120, 6, 060405 (2018) 3. Y. ROMACH ET. AL., PHYS. REV. APPLIED 11, 014064 (2019).

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Chemical and Biological Physics and Organic Chemistry Seminar

Date:

26

Tuesday

February

2019

Lecture / Seminar

Time: 11:00-12:00

Title: The Dynamics of Charged Excitons in Electronically and Morphologically Homogeneous Single-Walled Carbon Nanotubes

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof Michael J. Therien

Organizer: Department of Chemical and Biological Physics

Contact: ron.naaman@weizmann.ac.il

Abstract: The trion, a three-body charge-exciton bound state, offers unique opportunities ... Read more The trion, a three-body charge-exciton bound state, offers unique opportunities to simultaneously manipulate charge, spin and excitation in one-dimensional single-walled carbon nanotubes (SWNTs) at room temperature. Effective exploitation of trion quasiparticles requires fundamental insight into their creation and decay dynamics. Such knowledge, however, remains elusive for SWNT trion states, due to the electronic and morphological heterogeneity of commonly interrogated SWNT samples, and the fact that transient spectroscopic signals uniquely associated with the trion state have not been identified. Here length-sorted SWNTs and precisely controlled charge carrier-doping densities are used to determine trion dynamics using femtosecond pump-probe spectroscopy. Identification of the trion transient absorptive hallmark enables us to demonstrate that trions (i) derive from a precursor excitonic state, (ii) are produced via migration of excitons to stationary hole-polaron sites, and (iii) decay in a first-order manner. Importantly, under appropriate carrier-doping densities, exciton-to-trion conversion in SWNTs can approach 100% at ambient temperature. We further show that ultrafast pump-probe spectroscopy, coupled with these fundamental insights into trion formation and decay dynamics, enables a straightforward approach for quantitatively evaluating the extent of optically-driven free carrier generation (FCG) in SWNTs: this work provides fundamental new insights into how quantum yields for optically-driven FCG [Φ(Enn → h+ + e−)] in SWNTs may be modulated as functions of the optical excitation energy and medium dielectric strength. Collectively, these findings open up new possibilities for exploiting trions in SWNT optoelectronics, ranging from photovoltaics, photodetectors, to spintronics.

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Chemical and Biological Physics Guest Seminar

Date:

14

Thursday

February

2019

Lecture / Seminar

Time: 11:00

Title: A surface science approach to molecular and atomic contacts

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Dr. Richard Berndt

Organizer: Department of Chemical and Biological Physics

Contact: oren.tal@weizmann.ac.il

Abstract: Using low-temperature scanning tunneling microscopy we investigate molecular and ... Read more Using low-temperature scanning tunneling microscopy we investigate molecular and atomic structures at single crystal surfaces to explore their electron transport properties from the tunnelling range to ballistic transport. The experiments aim at maximizing the control over the junction properties and probe conductances, forces, shot-noise, and the emission of photons. We are particularly interested in molecules that exhibit switching behaviour of, e.g., their conformations or spin states. Results from metallic and molecular junctions will be presented.

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Towards plug and play parallel transmission for 7T human brain MRI with universal pulses

Date:

07

Thursday

February

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Nicolas Boulant

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Parallel transmission has been the most promising approach to counteract the rad ... Read more Parallel transmission has been the most promising approach to counteract the radiofrequency (RF) field inhomogeneity problem in MRI at ultra-high field. Despite tremendous progress made by the community for more than a decade, the technology yet has failed to be embraced in routine practice because of a more complex safety management and a cumbersome calibration procedure for each subject in the scanner. After thorough tests and validations to address the former point, universal pulses were proposed a couple of years ago to circumvent the workflow problem in head imaging at 7T. For a given RF coil, they consist of designing, offline, pulse solutions to mitigate the RF field inhomogeneity problem while being robust to intersubject variability, all within explicit hardware and safety constraints. This talk will present the latest sequence and pulse developments incorporating these solutions, now covering 3D (GRE, MPRAGE, TSE, MP-FLAIR, DIR, 3D-EPI) and 2D (GRE, MB-EPI) sequences with first routine results for fMRI (resting-state HCP-style, localizer paradigm) and ongoing clinical studies (Multiple Sclerosis), thereby making parallel transmission one step closer to clinical routine and at zero cost for the user. Perhaps interestingly, to reach the desired versatility and simplicity, some solutions were inspired from solid-state NMR methods. To date the proposed universal pulses cumulate tests on around 50 volunteers and across 4 sites. They have never failed to return brain images virtually free of B1+ artefacts at 7T.

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Extension of in-situ nanoindentation results by (S)TEM graphical data processing

Date:

06

Wednesday

February

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Vasily A. Lebedev

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Nanomechanical measurements allow us to determine mechanical characteristics o ... Read more Nanomechanical measurements allow us to determine mechanical characteristics of nano- and microobjects, which is required for further calculations of the mechanical parameters of the structures based on them. At the same time, in-situ measurements are carried out in the SEM and TEM chambers. Thus, it is possible to acquire graphic information that can supplement the indentation data. In this work, indentation of titania microspheres with different phase composition was tested by MEMS-based Hysitron PI-95 at Zeiss Libra 200MC TEM. Evaluation of the mechanical properties of microspheres in the elastic region was made according to the Hertz model. It turned out that annealing of the amorphous titania leads to an increase in the Young modulus, whereas the hydrothermal treatment reduces it from 27 to 4 Gpa. The differences in the destruction process was demonstrated for these kinds of particles. It has been shown, that hydrothermal treatment of titania microspheres leads to the formation of a reticular internal structure, whereas annealing results in sintering of the internal structure of microspheres. In the process of indentation, corresponding videos were also recorded, including the probe approach, indentation, and destruction of the microspheres. In order to process the videos we coded the program based on free Python packages. Using the Digital Image Correlation (DIC) algorithm, relative probe displacements were measured during indentation (Fig. 1a). The results obtained allowed us to clarify the calibration of the movement of the indenter in free sample tests, as well as to determine the drift function in real measurements. These results are important for long-term measurements, in particular creep tests. Based on graphical data we were able to determine the evolution of the shape of indented microspheres. During the video processing, areas of individual objects were determined, sizes of contact areas were calculated, and changes in linear dimensions of the deformed objects were determined (Fig. 1b). Therefore, a large amount of quantitative data was obtained from electron microscopy images. Fig.1 Illustration of probe displacement determination (a) and the shape evolution analysis

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Time-resolved neural activity and plasticity in behaving rodents using high field MRI

Date:

05

Tuesday

February

2019

Lecture / Seminar

Time: 14:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Noam Shemesh

Organizer: Department of Brain Sciences

Details: Light refreshments before the seminar Host: Prof. Elad Schneidman elad.schneidm ... Read more

Microstructural MRI: beyond the Standard Model

Date:

03

Sunday

February

2019

Lecture / Seminar

Time: 16:30-17:30

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Noam Shemesh

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Despite the importance of tissue microstructure in health and disease, its nonin ... Read more Despite the importance of tissue microstructure in health and disease, its noninvasive characterization remains a formidable challenge. Signal representations (diffusion/kurtosis tensors) are unspecific while tissue modelling using ideal geometries representing different cellular components have failed when scrutinized vis-à-vis histology: axon diameter, for example, is overestimated by factors of >6. Biophysical models characterizing signal behavior in specific diffusion-weighting regimes (power law scaling in “q” or “t”) have been more recently proposed as more reliable means for characterizing tissues. In recent years, the most prevalent biophysical model for diffusion in tissues was termed the “Standard Model”, consisting of a sum of gaussian components (nearly always two), one of which with zero diffusivity (stick). In the lecture, we will present validity regimes for the standard model and provide evidence for its limits. We will then propose a few novel means for characterizing

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Neuromodulation of dendritic excitability

Date:

29

Tuesday

January

2019

Lecture / Seminar

Time: 14:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Mickey London

Organizer: Department of Brain Sciences

Details: Host: Dr.Ivo Spiegel ivo.spiegel@weizmann.ac.il tel: 4415 For assistance with ... Read more

Abstract: The excitability of the apical tuft of layer 5 pyramidal neurons is thought to p ... Read more The excitability of the apical tuft of layer 5 pyramidal neurons is thought to play a crucial role in behavioral performance and synaptic plasticity. We show that the excitability of the apical tuft is sensitive to adrenergic neuromodulation. Using two-photon dendritic Ca2+ imaging and in vivo whole-cell and extracellular recordings in awake mice, we show that application of the a2A-adrenoceptor agonist guanfacine increases the probability of dendritic Ca2+ events in the tuft and lowers the threshold for dendritic Ca2+ spikes. We further show that these effects are likely to be mediated by the dendritic current Ih. Modulation of Ih in a realistic compartmental model controlled both the generation and magnitude of dendritic calcium spikes in the apical tuft. These findings suggest that adrenergic neuromodulation may affect cognitive processes such as sensory integration, attention, and working memory by regulating the sensitivity of layer 5 pyramidal neurons to top-down inputs.

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Proteins on membrane interfaces: Structure and dynamics of lipid-protein fibers from advanced fluorescence spectroscopy and microscopy methodologies

Date:

22

Tuesday

January

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Manuel Prieto

Organizer: Department of Chemical and Structural Biology

Understanding properties of advanced low-dimensional materials by low-voltage atomic-scale TEM experiments

Date:

22

Tuesday

January

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Ute Kaiser

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: A new type of transmission electron microscopes operating at electron energies b ... Read more A new type of transmission electron microscopes operating at electron energies between 80keV and 20keV has been developed to obtain structural and electronic properties of advanced low-dimensional material at the atomic scale. It allows to undercut most of the materials knock-on damage thresholds and enables sub-Angstroem resolution in an 4000x4000 pixels, single-shoot image down to 40keV by correcting not only the geometrical aberrations of the objective lens but also its chromatic aberration. During the imaging process, the interaction of the beam electrons with the low-dimensional material can, nevertheless, results in changes of the atomic structure due to ionization and radiolysis, and sophisticated sample preparation methods are employed to reduce these effects. In this talk, we briefly outline key instrumental and methodological developments and report on structural properties of low-dimensional materials. We not only determine the structure of the pristine material but also use the electron beam to engineer defined properties. Thus, we show for instance the dynamics of extended defects in MoTe2 and WS2 and the creation of a commensurate charge density wave (CDW) in a monolayer 1T-TaSe2, as well as properties of MnPS3, and moreover the dynamics and bond order changing of dirhenium molecule in single-walled carbon nanotubes. Finally we intercalate bilayer graphene by lithium and study in-situ lithiation and delithiation between bilayer graphene, identify single Li atoms as well as the structure of the new high density crystalline Li- phase.

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Connecting the dots: functional and structural insights into the Legionella pneumophila Dot/Icm secretion system

Date:

22

Tuesday

January

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Dr. David Chetrit

Organizer: Department of Biomolecular Sciences

Abstract: Type IV secretion systems (T4SS) are widespread in bacteria and despite their fu ... Read more Type IV secretion systems (T4SS) are widespread in bacteria and despite their fundamental importance in processes such as DNA conjugation and pathogenesis of plants, animals and humans, they are among the most complex and yet arguably the least understood secretion systems in the prokaryotic kingdom. Using live fluorescence microscopy in conjunction with cryo-electron tomography, we determined the in-situ structure of the T4SS of the respiratory pathogen Legionella pneumophila, called Dot/Icm. Unexpectedly, we have discovered that the major ATPases energizing center in the cytosol of the bacterial cell creates a dynamic assembly and forms a unique central channel in that it is constructed by a hexameric array of dimeric proteins. We have showed that the ATPase DotB cycles between the cytosol and the Type IV machine, indicating that it is involved in energizing the Type IV apparatus once a signal is received to initiate protein translocation. Our data changed the existing paradigm for how T4SS function and provides new insights for future studies that are important for a complete understanding of host pathogen interaction processes.

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Imaging Topological Materials

Date:

17

Thursday

January

2019

Colloquium

Time: 11:15-12:30

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Prof. Jenny Hoffman

Organizer: Faculty of Physics

Contact: hadar.lappin@weizmann.ac.il

Details: 11:00 – coffee, tea, and more

Abstract: Today’s electronic technology – the pixels on the screen and the process to ... Read more Today’s electronic technology – the pixels on the screen and the process to print the words on the page – are all made possible by the controlled motion of an electron’s charge. In the last decade, the discovery of topological band insulators with robust spin-polarized surface states has launched a new subfield of physics promising a new paradigm in computing. When topology is combined with strong electron correlations, even more interesting states of matter can arise, suggesting additional applications in quantum computing. Here we present the first direct proof of a strongly correlated topological insulator. Using scanning tunneling microscopy to probe the real and momentum space structure of SmB6, we quantify the opening of a Kondo insulating gap. Within that gap, we discover linearly dispersing surface states with the heaviest observed Dirac states in any material – hundreds of times the mass of a free electron. We show how single atom defects can scatter these surface states, which paves the way towards manipulating single atoms and thus controlling surface states and their excitations at the nanoscale.

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Using solution NMR spectroscopy to characterise the dynamics of side chains and ions in proteins

Date:

17

Thursday

January

2019

Lecture / Seminar

Time: 10:00-11:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Flemming Hansen

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Proteins are dynamic entities and function is often related to motions on time-s ... Read more Proteins are dynamic entities and function is often related to motions on time-scales from picoseconds to seconds. Understanding not only the backbone, but also the dynamics and interactions of side chains and ions within proteins is crucial, because side chains cover protein surfaces and are imperative for substrate recognition and both side chains and ions are key for most active sites in enzymes. New NMR-based methods, anchored in 13C-direct-detection, to characterise the motions and interactions of functional side chains in large proteins will be presented. One class of experiments is aimed at arginine side chains and allows the strength of interactions formed via the guanidinium group to be quantified. NMR measurements of the solvent exchange rate of labile guanidinium protons as well as measurements of the rotational motion about the Nε-Cζ bond allows for such quantifications. Secondly, a new class of NMR experiments is presented, which relies on 13C-13C correlation spectra and allows a general quantification of motion and structure of side chains in large proteins. The new 13C-13C correlation spectra are applied to a 82 kDa protein, where well-resolved spectra with minimal overlap are obtained within a few hours. NMR-based methods to characterise potassium binding in medium-large proteins will also be presented. Due to its size, 15N-ammonium can be used as a proxy for potassium to probe potassium binding in medium-large proteins. NMR pulse sequences will be presented to select specific spin density matrix elements of the 15NH4+ spin system and to measure their relaxation rates in order to characterise the rotational correlation time of protein-bound 15NH4+ as well as report on chemical exchange events of the 15NH4+ ion.

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Special Guest Seminar with Ariel Schwartz

Date:

17

Thursday

January

2019

Lecture / Seminar

Time: 10:00

Title: “Deep Semantic Genome and Protein Representation for Annotation, Discovery, and Engineering”

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Ariel Schwartz

Organizer: Department of Molecular Genetics

Contact: sandra.britton@weizmann.ac.il

Abstract: Computational assignment of function to proteins with no known homologs is still ... Read more Computational assignment of function to proteins with no known homologs is still an unsolved problem. We have created a novel, function-based approach to protein annotation and discovery called D-SPACE (Deep Semantic Protein Annotation Classification and Exploration), comprised of a multi-task, multi-label deep neural network trained on over 70 million proteins. Distinct from homology and motif-based methods, D-SPACE encodes proteins in high-dimensional representations (embeddings), allowing the accurate assignment of over 180,000 labels for 13 distinct tasks. The embedding representation enables fast searches for functionally related proteins, including homologs undetectable by traditional approaches. D-SPACE annotates all 109 million proteins in UniProt in under 35 hours on a single computer and searches the entirety of these in seconds. D-SPACE further quantifies the relative functional effect of mutations, facilitating rapid in-silico mutagenesis for protein engineering applications. D-SPACE incorporates protein annotation, search, and other exploratory efforts into a single cohesive model. We have recently extended this work from protein to DNA, enabling assignment of function to whole genomes and metagenomic contigs in seconds. Conserved genomic motifs as well as the functional impact of mutations in coding as well as non-coding genomic regions can be predicted directly from raw DNA sequence without the use of traditional comparative genomics approaches for motif detection, such as multiple sequence alignments, PSSMs, and profile HMMs.

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Chemical and Biological Physics and Organic Chemistry Seminar

Date:

15

Tuesday

January

2019

Lecture / Seminar

Time: 11:00

Title: The Renaissance of Sabatier CO2 Hydrogenation Catalysis

Location: Perlman Chemical Sciences Building

Lecturer: Charlotte Vogt‎

Organizer: Department of Chemical and Biological Physics

Contact: baran.eren@weizmann.ac.il

Abstract: The 100-year old Sabatier reaction, i.e. catalytic CO2 hydrogenation, is now see ... Read more The 100-year old Sabatier reaction, i.e. catalytic CO2 hydrogenation, is now seeing a renaissance due to its application in Power-to-Methane processes for electric grid stability and potential CO2 emission mitigation [1]. To date however, the fundamentals of this important catalytic reaction are still a matter of debate. This is partly due to the structure sensitive nature of CO2 hydrogenation: not all surface atoms of the active phase nanoparticles have the same specific activity. Recently, we have showed how the mechanism of catalytic CO2 methanation depends on Ni nanoparticle size using a unique set of well-defined silica-supported Ni nanoclusters (in the range 1-7 nm) and advanced characterization methods (i.e., operando FT-IR, and operando quick X-ray absorption spectroscopy) [2]. By utilizing fundamental theoretical concepts proving why CO2 is structure sensitive, and how CO2 is activated mechanistically and linking spectroscopic descriptors to these fundamental findings we ultimately leverage our understanding with a toolbox of structure sensitivity, and a library of reducible and non-reducible supports (SiO2, Al2O3, CeO2, ZrO2 and TiO2), tuning the selectivity and activity of methanation over Ni [3]. For example, we show that CO2 hydrogenation over Ni can and does form propane. This work contributes to our ability to produce “ideal” catalysts by improving the understanding of the catalytic sites and reaction pathways responsible for higher activity and even C-C coupling. This toolbox is thus not only useful for the highly active and selective production of methane within the Power-to-Methane concept, but also provides new insights for CO2 activation towards value-added chemicals thereby reducing the deleterious effects of this environmentally harmful molecule.

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G-CLEF and the search for Biomarkers in Exoplanets Atmospheres

Date:

08

Tuesday

January

2019

Colloquium

Time: 11:15-12:30

Location: Edna and K.B. Weissman Building of Physical Sciences

Lecturer: Dr. Sagi Ben-Ami

Organizer: Faculty of Physics

Contact: hadar.lappin@weizmann.ac.il

Details: 11:00 Coffee, tea and more

Abstract: Following a review of G-CLEF – a first light High-R spectrograph for the Giant ... Read more Following a review of G-CLEF – a first light High-R spectrograph for the Giant Magellan Telescope, I will present a concept extreme high resolution spectrograph optimized for molecular oxygen detection, a prominent biomarker in Earth atmosphere, using the transmission spectroscopy method. The instrument is based on the transmission properties of Fabry Perot Interferometers, and despite its modest dimensions is capable of achieving spectral resolution and sampling frequency in excess of R~300,000. I will discuss design parameters and the unique aspects that needs to be taken into account in the design of an FPI based instrument, and conclude with MC simulation results demonstrating the advantages of such a novel instrument.

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Fluorescent Sensors and Imaging agents

Date:

08

Tuesday

January

2019

Lecture / Seminar

Time: 11:00-12:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Tony James

Organizer: Department of Molecular Chemistry and Materials Science

Ben May Theory and Computation Seminar

Date:

07

Monday

January

2019

Lecture / Seminar

Time: 11:00

Title: New Mathematics to Understand Life One Photon at a Time

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Steve Pressé

Organizer: Department of Chemical and Biological Physics

Contact: gilad.haran@weizmann.ac.il

Abstract: Monitoring life in action—as it occurs in real time within the cellular cytopl ... Read more Monitoring life in action—as it occurs in real time within the cellular cytoplasm at the relevant single molecule scale—remains an important challenge. In order to see life unravel and monitor specific biomolecules as they diffuse and assemble in the cytoplasm, we create contrast with the cellular background by fluorescently labeling biomolecules. Yet the diffraction limit of light naively keeps us from peering into length scales comparable to those of single molecules. For this reason, the 2014 Chemistry Nobel Prize was awarded for separating signals from particles in time that cannot otherwise be separated in space to localize biomolecular structures to a precision beyond the diffraction limit. However, this process is slow and thus we compromise temporal resolution by separating signal in time. Here we present new Mathematics that make it possible to consider complex dynamical signals from which we can build a story of life in action starting from single, or very few, photons. The methods we present—motivated by the tools of Bayesian nonparametrics—show us how to achieve diffraction-limited tracking from signal previously considered insufficient. If time allows, we will discuss extensions of our methods to inferring diffusional dynamics from single photon arrivals from confocal imaging methods

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Chemical and Biological Physics Guest Seminar

Date:

30

Sunday

December

2018

Lecture / Seminar

Time: 09:30

Title: New Frontiers in Membrane Biophysics

Location: Perlman Chemical Sciences Building

Lecturer: Dr. Raya Sorkin

Organizer: Department of Chemical and Biological Physics

Contact: terry.debesh@weizmann.ac.il

Abstract: Membranes compartmentalize living matter into cells and subcellular structures. ... Read more Membranes compartmentalize living matter into cells and subcellular structures. Many life processes involve membrane topological changes and remodelling: the uptake of materials via endocytosis and secretion by exocytosis, the generation of intra or extra-cellular vesicles as well as various membrane fusion processes. In order to get to the bottom of these fundamental physiological processes, it is vital to study membrane mechanical properties and membrane deformation. In this talk I will present the results of our research on several aspects of vesicle generation and membrane fusion using single molecule techniques. By means of an AFM force spectroscopy study we characterized the mechanical properties of small natural vesicles, called extracellular vesicles (EVs). Investigating the mechanical properties of these vesicles and their lipid and protein content provided new insights into the still poorly understood processes underlying vesicle generation. Acoustic Force Spectroscopy (AFS) was the choice for our novel methodology to measure cell mechanical properties. It enabled our finding that uptake of EVs by cells changes cellular deformability, a process that may have implications in several disease states where EV levels are significantly elevated, such as malaria and breast cancer. Combining optical tweezers with confocal fluorescence microscopy was the perfect tool for the investigation of membrane remodelling by calcium sensor proteins which are crucial in neuronal communication. We discovered surprising differences between the action mechanisms of two structurally similar proteins, Doc2b and Synaptotagmin-1 (Syt1), as determined by quantifying the strength and probabilities of protein-induced membrane-membrane interactions. Overall these fundamentally new insights into central biological processes were possible by our biophysical characterization of membranes using a powerful combination of single molecule techniques: Optical tweezers combined with confocal fluorescent microscopy, AFS and AFM.

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Symmetry breaking in the synthesis of chiral nanocrystals

Date:

26

Wednesday

December

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Gil Markovich

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: In recent years we have been studying the handedness controlled synthesis of ino ... Read more In recent years we have been studying the handedness controlled synthesis of inorganic nanocrystals made of materials which crystallize in chiral space-groups. In the talk I will discuss the demonstration of strong chiral amplification in the colloidal synthesis of intrinsically chiral lanthanide phosphate nanocrystals, quantitatively measured via the circularly polarized luminescence of the lanthanide ions within the nanocrystals. Together with the group of Ori Cheshnovsky, we were able to measure single particle handedness though circularly polarized emission microscopy. We obtained 100% enantiomeric purity of the nanocrystals by using chiral tartaric acid molecules in the synthesis which act as an external “chiral field”, sensitively directing the amplified nanocrystal handedness through a discontinuous transition between left- and right-handed excess. The amplification involves also spontaneous symmetry breaking into either left- or right-handed nanocrystals below a critical temperature, in the absence of the tartaric acid molecules. These characteristics suggest a conceptual framework for chiral amplification, based on the statistical thermodynamics of critical phenomena, which we use (with Haim Diamant) to quantitatively account for the observations.

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Paramagnetic tagging of proteins for structural biology applications

Date:

25

Tuesday

December

2018

Lecture / Seminar

Time: 15:00-16:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Xun-Cheng Su

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Site-specific installation of paramagnetic lanthanide ions in proteins is a powe ... Read more Site-specific installation of paramagnetic lanthanide ions in proteins is a powerful method in delineating the structures, dynamics and interactions of proteins by NMR and EPR. Since most proteins do not have a paramagnetic center, efforts towards site-specific labeling of proteins with paramagnetic ions have thus been made via thiol chemistry, click chemistry, and molecular biology. The formation of disulfide bond between a protein and the paramagnetic tag is mostly applied in protein modifications, whereas the disulfide bond tether succumbs to low stability in reducing conditions or high pH. We have been focusing on development of paramagnetic tagging proteins in formation of a stable thioether bond for analysis of proteins in vitro and in cells using NMR and EPR. A number of stable paramagnetic tags have been designed and the performance of the respective protein conjugates has been evaluated in vitro and in cells by high resolution NMR spectroscopy. Using these high-performance paramagnetic tags, we were able to determine the 3D structure of a protein in live cells and 3D structure of unstable and short-lived thioester intermediate of Sortase A with pseudocontact shifts (PCSs) as structural restraints.

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“Anharmonicity and Electron-Phonon Interaction in Dielectrically-Confined 2D Materials”

Date:

19

Wednesday

December

2018

Lecture / Seminar

Time: 14:00-15:30

Location: Perlman Chemical Sciences Building

Lecturer: Matan Menahem

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Electron-phonon interaction (EPI) is the influence of structural dynamics on cha ... Read more Electron-phonon interaction (EPI) is the influence of structural dynamics on charge-carrier’s band structure, by changes in the potential acting on a charge carrier due to atomic displacements. When the atomic displacements are anharmonic, and the quasi-harmonic approximation is no longer sufficient, the existing theory fails to explain or predict the macroscopic properties of the material. In quantum confined systems with dielectric mismatch between well and barrier, the effect of atomic displacements on the dielectric environment of charge carriers is greater due to dielectric confinement. 2D hybrid halide perovskites (HHPs) are easy to synthesize, easily tunable dielectric confined materials with pronounced optical response, even at room temperature. Recent studies show the effect of anharmonicity on the optical properties of 3D perovskites and strong EPI in 2D HHPs, affected by temperature. I aim to investigate the effect of anharmonicity on the dielectric environment of charge carriers in prototypical dielectric confined 2D HHPs, using various methods of optical spectroscopy. I hypothesize that anharmonicity would decrease the excitonic binding energy and electron-phonon scattering, due to more efficient charge screening and phonon-phonon scattering.

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Halide Exchange in Single Crystal Halide Perovskites

Date:

17

Monday

December

2018

Lecture / Seminar

Time: 14:00-15:00

Location: Perlman Chemical Sciences Building

Lecturer: Aya Osherov

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Halide Perovskites (HaPs) have remarkable electronic and optical characteristics ... Read more Halide Perovskites (HaPs) have remarkable electronic and optical characteristics, but much is still unknown regarding the connection between their physical and chemical properties. Cation or anion substitution can change the optical absorption edge, with or without change of structure. In this work I explored the halide exchange reaction in methylammonium lead tri-halides single crystals (SCs) in order to understand the process of exchange and the stability of the product(s). I demonstrate halide exchange in mm-sized SCs, achieved by diffusion. Using the Boltzmann-Matano method and diffusion profiles obtained by electron dispersive spectroscopy it is possible to evaluate the halide diffusion coefficients, which are not constant and depend on the mixture of halides. For all permutations, the change in composition as result of the diffusion, strongly affects the optical and electrical properties and especially the band gap of the semiconducting crystals, as seen in cathodoluminescence measurements in the scanning electron microscope. While these gradients cause a lattice parameter change and may cause a symmetry change, X-ray diffraction measurements show that if the interchanged halide pair is such that their sizes are relatively similar (e.g., and , and but not and ) the resulting material remains surprisingly single crystalline. These findings are valid, no matter which one of the two halides is being exchanged. These results suggest that for these similar-sized halide pairs, this exchange occurs through a solid-state chemical reaction such that the resulting crystal orientation is determined by that of the initial crystal.

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“Diffusion NMR of out-of-equilibrium mixtures”

Date:

11

Tuesday

December

2018

Lecture / Seminar

Time: 09:30

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Jean-Nicolas Dumez

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: The NMR spectra of molecular species in solution mixtures can be separated wit ... Read more The NMR spectra of molecular species in solution mixtures can be separated with diffusion-ordered NMR spectroscopy (DOSY), a ‘virtual chromatography’ approach based on the measurement of translational diffusion coefficients. Classic DOSY experiments, however, require several minutes are not applicable to many important time-evolving mixtures. Taking advantage of the concept of spatial encoding, we show here that DOSY data can be collected in a single scan of less than one second for several types of out-of-equilibrium mixtures. SPEN provides an acceleration of DOSY experiments by several orders of magnitude. SPEN DOSY pulse sequences are developed, that compensate for convection effects and are suitable for measurements in low-viscosity organic solvents, a requirement to monitor organic chemical reactions. We also show how to collect multiple consecutive scans from short-lived, non-renewable signals produced by dissolution dynamic nuclear polarisation (D-DNP), which is a versatile and powerful hyperpolarisation method. These methodological developments are supported by advanced numerical simulations, based on a Fokker-Plank formalism to describe simultaneously the spin and spatial dynamics. An exemple of hyperpolarised sample is given with a model mixture of small molecules, while the ability to monitor a reacting mixture is illustrated with a diamination reaction in dichloromethane. The proposed UF DOSY methodology may contribute towards a real-time diffusion NMR analysis of mixtures, to help in the identification of a sample’s components and in the analysis of molecular interactions.

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“Diffusion NMR of out-of-equilibrium mixtures”

Date:

11

Tuesday

December

2018

Lecture / Seminar

Time: 09:30-10:30

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Jean-Nicolas Dumez

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: The NMR spectra of molecular species in solution mixtures can be separated with ... Read more The NMR spectra of molecular species in solution mixtures can be separated with diffusion-ordered NMR spectroscopy (DOSY), a ‘virtual chromatography’ approach based on the measurement of translational diffusion coefficients. Classic DOSY experiments, however, require several minutes are not applicable to many important time-evolving mixtures. Taking advantage of the concept of spatial encoding, we show here that DOSY data can be collected in a single scan of less than one second for several types of out-of-equilibrium mixtures. SPEN provides an acceleration of DOSY experiments by several orders of magnitude. SPEN DOSY pulse sequences are developed, that compensate for convection effects and are suitable for measurements in low-viscosity organic solvents, a requirement to monitor organic chemical reactions. We also show how to collect multiple consecutive scans from short-lived, non-renewable signals produced by dissolution dynamic nuclear polarisation (D-DNP), which is a versatile and powerful hyperpolarisation method. These methodological developments are supported by advanced numerical simulations, based on a Fokker-Plank formalism to describe simultaneously the spin and spatial dynamics. An exemple of hyperpolarised sample is given with a model mixture of small molecules, while the ability to monitor a reacting mixture is illustrated with a diamination reaction in dichloromethane. The proposed UF DOSY methodology may contribute towards a real-time diffusion NMR analysis of mixtures, to help in the identification of a sample’s components and in the analysis of molecular interactions.

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A new way cancer cells cope with proteotoxic stress

Date:

28

Wednesday

November

2018

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Dr. Peter Tsvetkov

Organizer: Department of Biomolecular Sciences

Abstract: Maintaining protein homeostasis is crucial for cell survival and coping with env ... Read more Maintaining protein homeostasis is crucial for cell survival and coping with environmental stressors. The mechanisms that cells deploy to cope with increased proteotoxic burden are still poorly understood. In this work, using genetic screens, cancer genomics analysis and biochemical validations we determine a new way cancer cells can cope with increased proteotoxic burden. This mechanism involves two complementary cellular adaptations that are sufficient to promote cell survival when proteasome function is suppressed. These cellular adaptations are naturally occurring in many cancer types and evolutionary conserved and entail a vulnerability that can be targeted with a newly identified mitochondrial pathway inhibitor for which the unique mechanism of action we describe.

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Vision and Robotics Seminar

Date:

22

Thursday

November

2018

Lecture / Seminar

Time: 12:15-13:30

Title: System-Aware Compression: Optimizing Imaging Systems from the Compression Standpoint

Location: Jacob Ziskind Building

Lecturer: Yehuda Dar

Organizer: Faculty of Mathematics and Computer Science

Contact: efrat.levitsky@weizmann.ac.il

Small Animal Brain Diffusion Imaging: From White Matter Evolution to Brain Disease Diagnosis

Date:

22

Thursday

November

2018

Lecture / Seminar

Time: 10:00-11:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Hao Lei

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: White matter (WM) plays a central role in the long-range connection and coordina ... Read more White matter (WM) plays a central role in the long-range connection and coordinated communication between different brain regions. Diffusion magnetic resonance imaging (DMRI) uses the diffusion of water molecules as an endogenous probe to characterize WM microstructural integrity in and structural connectivity of the brain. The usefulness of DMRI in clinical settings and basic neuroscience research has been fully demonstrated. Our laboratory has been using DMRI and DMRI-based tractography to study normal and diseased brain of small animals (i.e., rodents and tree shrews) in the last ten years. In this talk, I will share some of these experiences, focusing on two stories. The first is the use of a super-resolution DMRI approach to reveal fine anatomical architecture in the brain of tree shew, and how the WM configuration in this squirrel-like mammal compared with the others on the evolutionary tree. The second is concerning the histological underpinning of dMRI changes in rat models of neurodegenerative diseases.

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Spotlight on Science

Date:

21

Wednesday

November

2018

Lecture / Seminar

Time: 12:00

Title: Single-Cell Genomics Reveals a Novel Regulatory Role of the Immune System in Obesity

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Diego Jaitin

Contact: yaelpj@weizmann.ac.il

Novel Nanophotonics in the Ultrafast Transmission Electron Microscope

Date:

21

Wednesday

November

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Ido Kaminer

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: We will discuss new science and applications enabled by the ultrafast interactio ... Read more We will discuss new science and applications enabled by the ultrafast interactions of electrons and laser pulses inside electron microscopes. Such interactions enable novel microscopy techniques with time-correlated measurements and the new method of stimulated electron energy loss spectroscopy (SEELS). From the standpoint of fundamental science, controlling ultrafast strong-field interactions inside electron microscopes enable exploring new principles for generating extreme ultraviolet and x-ray radiation, as well as novel light-matter interactions in nanostructures and in 2D materials.

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Development of Memory Systems in the Human Brain

Date:

20

Tuesday

November

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Noa Ofen

Organizer: Department of Brain Sciences

Abstract: Episodic memory – the ability to encode, maintain and retrieve information – ... Read more Episodic memory – the ability to encode, maintain and retrieve information – is critical for everyday functioning at all ages, yet little is known about the development of episodic memory systems and their brain substrates. In this talk, I will present data from a series of studies with which we begin to identify how brain development underlies changes in episodic memory throughout childhood and adolescence. Using structural MRI data, I will present evidence demonstrating how brain development sets limits on cognitive developmnet. I will show that individual differences in fine structural measures of the hippocampus, a region known to be critical for episodic memory, and the prefrontal cortex (PFC), a region that shows protracted structural development, partially explain age-related improvement in episodic memory. Using functional neuroimaging methods including functional MRI (fMRI) and electrocorticography (ECoG), I will present our ongoing attempts to characterize the neural correlates of episodic memory development. Evidence from fMRI studies suggest that age differences in episodic memory functioning may primarily relate to age differneces in PFC activation and connectivity patterns. Intracranial evidence further underscores the role of the PFC in memory and reveals that spatiotemporal propagation of frontal activity supports memory formation in children. I will highlight the challenges in investigaitons of brain-behavior relations in pediatric populations and discuss how advances in methodologies provide unique opportunities for moving towards a mechanistic understanding of developmental changes.

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Nuclear Genome Nanostructure Imaging at Single Molecule Resolution

Date:

20

Tuesday

November

2018

Lecture / Seminar

Time: 10:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Prof. Christoph Cremer

Organizer: Department of Molecular Genetics

Contact: Ingrid.lehrer@weizmann.ac.il

Abstract: Super-resolution fluorescence microscopy allows quantitative studies of nuclear ... Read more Super-resolution fluorescence microscopy allows quantitative studies of nuclear genome organization on the nanoscale1. Here we report on results obtained by single molecule localization microscopy (SMLM). SMLM has made possible to explore chromatin nanostructure down to the imaging of single histones, of short oligosequences, or single DNA sites; presently, an intranuclear optical resolution down to the 5 nm range has been achieved. Applying a novel SMLM technique (fBALM)2, the DNA distribution across entire nuclei at nanoscale resolution was quantitatively determined, localizing in individual nuclear optical sections up to ~4 million individual DNA bound single fluorophore molecule positions, corresponding to about one position per nucleosome. Intensity profile analyses of the intranuclear DNA distributions indicated sharp transitions between high-density domains and low-density compartments, with differences up to almost two orders of magnitude; compacted regions had a minimum diameter down to ca. 50 nm diameter. In contrast to these results, conventional resolution imaging of the same nuclear sites indicated only small differences in the compaction of different regions, combined with very smooth density transitions. Taken together, the quantitative compaction estimates support models of a nuclear organization based on highly compartmentalized chromatin nanostructures3.

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Chemical and Biological Physics Special Seminar

Date:

13

Tuesday

November

2018

Lecture / Seminar

Time: 11:00

Title: Studying cell dynamics using Quantitative Phase Imaging (QPI)

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Gabriel Popescu

Organizer: Department of Chemical and Biological Physics

Contact: nir.gov@weizmann.ac.il

Abstract: Light scattering limits the quality of optical imaging of unlabeled biospecimens ... Read more Light scattering limits the quality of optical imaging of unlabeled biospecimens: too little scattering and the sample is transparent, exhibiting low contrast, and too much scattering washes the structure information altogether. Recent advances in QPI, an approach by which the pathlength shifts induced by a specimen are mapped at each point in the field of view, allow us to connect the two regimes. We developed spatial light interference microscopy (SLIM) as a high-sensitivity, high-resolution QPI method, which open new applications for studying structure and dynamics. SLIM provides interesting data on cell growth and intracellular transport, specifically, it distinguishes between random and deterministic cargo motion. We measured subtle vesicle transport changes following optogenetic stimulation of live cells. Based on principles of holography, we developed a new optical technique for measuring cell traction. We performed simultaneous measurements of cell growth and cellgenerated forces and showed their evolution during cell differentiation. However, SLIM works best for thin specimens, such as single cell layers and tissue slices. To expand this type of imaging to thick, multiply scattering media, we developed gradient light interference microcopy (GLIM). GLIM is capable of suppressing the incoherent background due to multiple scattering. We demonstrate the use of GLIM to image various samples bovine embryos and live brain slices. Intrinsic dynamic markers promise to provide information about embryo viability, prior to implantation.

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Diffusion MRI methods derived from solid-state NMR spectroscopy

Date:

08

Thursday

November

2018

Lecture / Seminar

Time: 09:30-10:00

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Daniel Topgaard

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Diffusion MRI is an excellent method for detecting subtle microscopic changes of ... Read more Diffusion MRI is an excellent method for detecting subtle microscopic changes of the living human brain, but often fails to assign the experimental observations to specific structural properties such as cell density, size, shape, or orientation. When attempting to solve this problem, we have chosen to disregard essentially all previous work in the field of diffusion MRI, and instead translate data acquisition and processing schemes from multidimensional solid-state NMR spectroscopy [1, 2]. Key elements of our approach are q-vector trajectories and correlations between isotropic and directional diffusion encoding. By approximating the water displacement probability as a sum of anisotropic Gaussians, the voxel composition can be reported as a diffusion tensor distribution where each component of the distribution corresponds to a distinct tissue environment. Our new methods yield estimates of the complete diffusion tensor distribution or well-defined statistical properties thereof, such as the mean and variance of isotropic diffusivities, mean-square anisotropy, and orientational order parameter, which derive from analogous parameters in solid-state NMR and can be related to the structural properties of the tissue. This presentation will give an overview of the new methods, including basic physical principles, pulse sequences, and data processing, as well as examples of applications in soft matter systems from lipid membranes to living brains.

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Diffusion MRI methods derived from solid-state NMR spectroscopy

Date:

08

Thursday

November

2018

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Daniel Topgaard

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Diffusion MRI is an excellent method for detecting subtle microscopic changes of ... Read more Diffusion MRI is an excellent method for detecting subtle microscopic changes of the living human brain, but often fails to assign the experimental observations to specific structural properties such as cell density, size, shape, or orientation. When attempting to solve this problem, we have chosen to disregard essentially all previous work in the field of diffusion MRI, and instead translate data acquisition and processing schemes from multidimensional solid-state NMR spectroscopy [1, 2]. Key elements of our approach are q-vector trajectories and correlations between isotropic and directional diffusion encoding. By approximating the water displacement probability as a sum of anisotropic Gaussians, the voxel composition can be reported as a diffusion tensor distribution where each component of the distribution corresponds to a distinct tissue environment. Our new methods yield estimates of the complete diffusion tensor distribution or well-defined statistical properties thereof, such as the mean and variance of isotropic diffusivities, mean-square anisotropy, and orientational order parameter, which derive from analogous parameters in solid-state NMR and can be related to the structural properties of the tissue. This presentation will give an overview of the new methods, including basic physical principles, pulse sequences, and data processing, as well as examples of applications in soft matter systems from lipid membranes to living brains.

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Diffusion MRI methods derived from solid-state NMR spectroscopy

Date:

08

Thursday

November

2018

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Daniel Topgaard

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Diffusion MRI is an excellent method for detecting subtle microscopic changes o ... Read more Diffusion MRI is an excellent method for detecting subtle microscopic changes of the living human brain, but often fails to assign the experimental observations to specific structural properties such as cell density, size, shape, or orientation. When attempting to solve this problem, we have chosen to disregard essentially all previous work in the field of diffusion MRI, and instead translate data acquisition and processing schemes from multidimensional solid-state NMR spectroscopy [1, 2]. Key elements of our approach are q-vector trajectories and correlations between isotropic and directional diffusion encoding. By approximating the water displacement probability as a sum of anisotropic Gaussians, the voxel composition can be reported as a diffusion tensor distribution where each component of the distribution corresponds to a distinct tissue environment. Our new methods yield estimates of the complete diffusion tensor distribution or well-defined statistical properties thereof, such as the mean and variance of isotropic diffusivities, mean-square anisotropy, and orientational order parameter, which derive from analogous parameters in solid-state NMR and can be related to the structural properties of the tissue. This presentation will give an overview of the new methods, including basic physical principles, pulse sequences, and data processing, as well as examples of applications in soft matter systems from lipid membranes to living brains

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Machine Learning and Statistics Seminar

Date:

07

Wednesday

November

2018

Lecture / Seminar

Time: 11:15-12:30

Title: Estimation in extreme noise levels with application to cryo-electron microscopy

Location: Jacob Ziskind Building

Lecturer: Tamir Bendory

Organizer: Faculty of Mathematics and Computer Science

Contact: efrat.levitsky@weizmann.ac.il

Ultrahigh Field MR Imaging in the Mesosphere Where Physics, Life Sciences, Computer Sciences and Medicine Meet

Date:

28

Sunday

October

2018

Lecture / Seminar

Time: 16:30-17:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Thoralf Niendorf

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: The development of ultrahigh field magnetic resonance (UHF-MR) is moving forward ... Read more The development of ultrahigh field magnetic resonance (UHF-MR) is moving forward at an amazing speed that is breaking through technical barriers almost as fast as they appear. UHF-MR has a staggering number of potential uses in neuroscience, neurology, radiology, cardiology, internal medicine, physiology, oncology, nephrology, ophthalmology and other related clinical fields. With over 50,000 MR examinations already performed at 7.0 Tesla, the reasons for moving UHF-MR into clinical applications are more compelling than ever. The value UHF-MR has already proven itself many times over at lower field strengths; now 7.0 T has opened a window on tissues, organs, and (patho)physiological processes that have been largely inaccessible in the past. Images from these instruments have revealed new aspects of the anatomy, functions and physio-metabolic characteristics of the brain, heart, joints, kidneys, liver, eye, and other organs/tissues, at an unparalleled quality. 50,000 sounds like a large number, but in fact we have barely cracked open the door and have yet to truly assess what lies on the other side. To this end this presentation documents advances and progress of UHF-MR with the goal to engage the interest of clinical adopters, basic scientists, engineers, and translational researchers from many areas. To meet this goal the traits, challenges and opportunities for discovery of human UHF-MRI will be surveyed. The considerations run from technical advances to early clinical applications. Examples of UHF-MR strategies are demonstrated. Their added value over the kindred counterparts at lower fields is explored along with an outline of research promises. Encouraging developments into enabling multiple channel radiofrequency (RF) antennae concepts (Figure 1) are reviewed. Frontier applications of MR at 7.0 T are surveyed including cardiac imaging (Figure 1), ophthalmic MRI and high spatial resolution MRI of the brain. Heteronuclear UHF-MR applications are explored with a focus on in vivo mapping of electrolytes including potassium MRI and sodium MRI (Figure 1). Practical obstacles of UHF MR are outlined including MR safety. Insights into RF heating induced by conductive stents and implants are provided. Current trends in UHF-MR are considered together with their clinical implications. A concluding section ventures a glance beyond the horizon including explorations into Extreme Field MR (EF-MR) which envisions human MR at 20 Tesla, which is an important leap of the imagination because it aims to fill a crucial "resolution gap" in our understanding of human biology (39, 40). It is the speakers hope that this presentation will convey the seeds of this vision and inspire the audience to become pioneers in these amazingly promising new areas of biomedical research: ultrahigh field and extreme field MR..

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Unravelling the tumor immune microenvironment by multiplexed imaging

Date:

28

Sunday

October

2018

Lecture / Seminar

Time: 15:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. Leeat Yankielowicz-Keren

Organizer: Department of Immunology,Department of Molecular Cell Biology,Department of Molecular Genetics

Contact: Ingrid.lehrer@weizmann.ac.il

Interactive Microscopy Image Analysis with IMARIS

Date:

28

Sunday

October

2018

Lecture / Seminar

Time: 10:30

Location: Max and Lillian Candiotty Building

Lecturer: Georgia Golfis

Organizer: Department of Life Sciences Core Facilities

Contact: ofra.golani@weizmann.ac.il

Details:

Information processing at hippocampal synapses

Date:

18

Thursday

October

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. J. Simon Wiegert

Organizer: Department of Brain Sciences

Details: Host: Dr. Ofer Yizhar ofer.yizhar@weizmann.ac.il tel: 6957 For assistance wit ... Read more

Abstract: Synapses change their strength in response to specific activity patterns. This f ... Read more Synapses change their strength in response to specific activity patterns. This functional plasticity is assumed to be the brain’s primary mechanism for information storage. We combine optogenetic and chemogenetic control of synapses in rat hippocampal slice cultures with calcium and glutamate imaging of their spines and boutons. This approach enables us to perform all-optical quantal analysis of synaptic transmission, to induce long-term potentiation (LTP), long-term depression (LTD), or both forms of plasticity in sequence, to chronically manipulate activity and to follow the fate of individual synapses for 7 days. We ask how plasticity and activity are integrated at Schaffer collateral synapses over time. Our findings suggest that activity-dependent changes in the transmission strength of individual synapses are transient, but have long-lasting consequences for synaptic lifetime.

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“From “Crowdoxidation” to Organoselenide C-E Bond Cleavage: Enlisting the help of Chalcogens in Analysis of Biological Systems Trough Novel Probe Design”

Date:

25

Tuesday

September

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. David G. Churchill

Organizer: Department of Molecular Chemistry and Materials Science

Surface Micro-Spectroscopy and Spectro-Microscopy Conference website

Abstract: Our laboratory is studying small molecule selenium-containing organic and organo ... Read more Our laboratory is studying small molecule selenium-containing organic and organometallic systems for their potential selective fluorescence imaging properties; our goal is to eventually probing aspects of neurodegenerative disease and disease models in a more precise way based on the present state of the art. Like some transition metals, heavier chalcogens also have capacity for redox with common changes in their valence state from 2 to 4 and from 4 to 6 being possible. Also, reduced heavier chalcogenide centers such as selenium have the ability for metal chelation. The optical characteristics are sometimes profoundly changed by an additional 2+ oxidation state at e.g. a selenium atom when the Se is in an aromatic ring or as a direct aryl substituent to a fluorogenic framework. While the atom which can become chemically oxidized may be contained within an aromatic ring, or present as a substituent, there is also the possibility for C-E bond rupture; C-Se bond c! leavage was studied with selective biothiol detection in mind and therefore, the extent of Se-C rupture possible is a design parameter in these small fluorogenic molecules and its study is ongoing. Sulfur chemistry in biology is dynamic and diverse; therefore, we are hereby exploring the extent of versatility available for selenium in small synthetic molecules in the context of biology, and specifically, towards better understanding and addressing aging and neurodegenerative disease research.

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Surface Micro-Spectroscopy and Spectro-Microscopy

Date:

02

Sunday

September

2018

-

06

Thursday

September

2018

Conference

Time: 08:00

Location: David Lopatie Conference Centre

Contact: sidney.cohen@weizmann.ac.il

In situ structural studies of the cell cytoskeleton by cryo-electron tomography

Date:

27

Monday

August

2018

Lecture / Seminar

Time: 14:00-15:00

Title: Special Guest Seminar

Location: Max and Lillian Candiotty Building

Lecturer: Prof. Ohad Medalia

Organizer: Department of Biological Regulation

Contact: tamar.cohen@weizmann.ac.il

Abstract: Recent advances in cryo-electron microscopy revolutionized the possibilities and ... Read more Recent advances in cryo-electron microscopy revolutionized the possibilities and capabilities of structural analysis. This presents an exciting opportunity to explore the architecture of macromolecular-complexes which could not be crystallized, but also opens a window into in situ structural determination. Here, I will discuss the excitement in resolving macromolecular structures at atomic resolution and report on advances and challenges in studying molecular assemblies in individual cells and multicellular organisms at ~1nm of resolution. A special focus will be given to the functional organization of the cell’s cytoskeleton, i.e., the actin cytoskeleton, intermediate filaments and nuclear lamins. Our study indicates that in situ structural biology, at high-resolution, shed light on structural assemblies that can only be studied in their native environment, i.e. the cell.

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“Determination of Nanocatalyst Structure “on-the-Fly” by a Neural Network Approach”

Date:

11

Wednesday

July

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Anatoly Frenkel

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Tracking the structure of heterogeneous catalysts under operando conditions rema ... Read more Tracking the structure of heterogeneous catalysts under operando conditions remains a challenge due to the paucity of experimental techniques that can provide atomic-level information for catalytic metal species. Here we report on the use of X-ray absorption spectroscopy (XANES and EXAFS) and supervised machine learning (SML) for determining the three-dimensional geometry of metal catalysts. Artificial neural network (NN) is used to unravel the hidden relationship between the XANES features and catalyst geometry. In the case of EXAFS, NN is used to obtained the radial distribution function directly from the spectra. Our approach allows one to solve the structure of a metal catalyst from its experimental XANES and EXAFS spectra. These applications are demonstrated by reconstructing the average size, shape and morphology of well-defined platinum nanoparticles1 and monitoring structural changes in bulk Fe during its structural phase transition from BCC to FCC upon heating.2 This method is applicable to the determination of nanomaterial structure in operando studies It also allows on-the-fly analysis, and is a promising approach for high-throughput and time-dependent studies.

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MODELING PROTEIN CONFORMATIONAL CHANGES WITH CROSS-LINKS AND SAXS PROFILES

Date:

03

Tuesday

July

2018

Lecture / Seminar

Time: 14:00-15:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Dr. Dina Schneidman

Organizer: Department of Chemical and Structural Biology

Abstract: Proteins generally populate multiple structural states in solution. Transitions ... Read more Proteins generally populate multiple structural states in solution. Transitions between these states are important for function, such as allosteric signaling and enzyme catalysis. Structures solved by X-ray crystallography provide valuable, but static, atomic resolution structural information. In contrast, cross-linking mass spectrometry (XLMS) and small angle X-ray scattering (SAXS) datasets contain information about conformational and compositional states of the system. The challenge lies in the data interpretation since the cross-links in the data often comes from multiple structural states. We have developed a novel computational method that simultaneously uncovers the set of structural states that are consistent with a given dataset (XLMS or SAXS). The input is a single atomic structure, a list of flexible residues, and an experimental dataset. The method finds multi-state models (models that specify two or more co-existing structural states) that are consistent with the data. The method was applied on multiple SAXS and XLMS datasets, including large multi-domain proteins and proteins with long disordered fragments. The applicability of the method extends to other datasets, such as 2D class averages from Electron Microscopy, and residual dipolar couplings.

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Sensory processing across behavioral and neuromodulatory states

Date:

03

Tuesday

July

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Yuval Nir

Organizer: Department of Brain Sciences

Details: Host: Dr.Ivo Spiegel ivo.spiegel@weizmann.ac.il tel: 4415 For assistance with ... Read more

Abstract: "Sensory disconnection" – conditions when the same sensory stimulus does not r ... Read more "Sensory disconnection" – conditions when the same sensory stimulus does not reliably affect behavior or subjective experience - is a defining feature of sleep, and similar processes may occur during light anesthesia or during cognitive lapses in wakefulness. What are the changes in brain activity that mediate sensory disconnection? In a series of studies in humans and rodents, we investigate how "disconnected" states affect sensory processing. The first set of studies reveals differences in neuronal responses to identical sensory stimuli across states. We find that in humans, cognitive lapses after sleep deprivation involve attenuated and delayed single-neuron responses in MTL co-occurring with local slow/theta waves. In the auditory domain, we show in both rodents and humans that responses in sleep and light anesthesia are preserved up to A1, challenging the classic "thalamic gating" notion, but robust attenuation occurs later in high-level cortical regions. In addition, sleep affects more strongly responses that require integration over long time intervals, and responses to high-frequency content. The second set of studies investigates the underlying mechanisms, testing the potential role of locus coeruleus-noradrenaline (LC-NE) neuromodulation. In rats, we test how NE signaling affects the probability to wake up from sleep in response to sounds. We establish a new approach for selective in-vivo LC optogenetics by showing effects on spiking activity, evoked sleep-wake transitions, and pupil dilation. Combined LC and auditory stimulation synergistically increases the probability of awakenings beyond independent effects of sound and laser alone, supporting a role for LC-NE activity in mediating sensory responses. We also tested the effects of NE levels on sensory perception and sensory-evoked activity (EEG, fMRI) in awake humans. Pharmacologically manipulating NE levels in double-blind placebo-controlled experiments, we found that NE modulates sensitivity and accuracy of visual perception without significant effects on decision bias (criterion). In addition, NE increased the fidelity of late EEG visual responses, and selectively modulated BOLD fMRI responses in high-order visual cortex, suggesting that NE plays an enabling causal role in visual awareness by affecting late visual processing.

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Hyperion Mass Cytometry Imaging System

Date:

27

Wednesday

June

2018

Lecture / Seminar

Time: 09:00-11:00

Location: Max and Lillian Candiotty Building

Lecturer: Dr. Roberto Spada

Organizer: Department of Life Sciences Core Facilities

Contact: tomer-meir.salame@weizmann.ac.il

Details: Imaging mass cytometry (IMC) is a novel multiparametric, quantitative technique ... Read more

New era in cryo electron microscopy reflected in studies of a bacteriophage phage at near atomic resolution

Date:

21

Thursday

June

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Elena Orlova

Organizer: Department of Chemical and Structural Biology

FROM CANCER GENOMICS TO IMMUNOTHERAPY Conference website

Abstract: During the last decade electron microscopy become a powerful tool in structural ... Read more During the last decade electron microscopy become a powerful tool in structural studies of large biological complexes. Cryo electron microscopy enabled us to reveal molecular dynamics of the complexes by analysis of samples in solution. This was made possible by long-standing efforts in sample preparations (cryo-EM imaging), in development of hardware, automation in data collection, methods in image analysis and, eventually, interpretation of results. Here I would like to share my experience in using these approaches in analysis of structural organisation of bacteriophages exemplified by the SPP1 phage. It is important to highlight critical steps in obtaining near-atomic resolution structures of the biocomplexes. We have obtained high resolution structures of main components of the phage such as a capsid and its nano-motor engaged into packaging of genome and its release.

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Chemical and Biological Physics Guest Seminar

Date:

19

Tuesday

June

2018

Lecture / Seminar

Time: 09:30

Title: The fascinating photochemistry of Photosystem II unraveled with the use of low temperature EPR spectroscopy

Location: Perlman Chemical Sciences Building

Lecturer: Dr Andrea Pavlou

Organizer: Department of Chemical and Biological Physics

Contact: amit.finkler@weizmann.ac.il

FROM CANCER GENOMICS TO IMMUNOTHERAPY

Date:

19

Tuesday

June

2018

Conference

Time: 08:00-14:00

Location: Dolfi and Lola Ebner Auditorium

Contact: yardena.samuels@weizmann.ac.il

The multi-scale structure of chromatin in the nucleus

Date:

03

Sunday

June

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Yuval Garini

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: The DNA in a human cell which is ~3 meters long is packed in a tiny nucleus of ... Read more The DNA in a human cell which is ~3 meters long is packed in a tiny nucleus of ~10 μm radius. The DNA is surrounded by thousands of proteins, and it is highly dynamic while taking part in the process of protein expression and cell division. Nevertheless, it must stay organized to prevent chromosome entanglement. Studying this nanometer – micrometer scale structure is difficult, as it falls short of the optical resolution, while electron microscopy is limited due to the need to fixate the sample. We therefore adopted various methods for studying the organization of the genome in the nucleus, including live-cell imaging, time-resolved spectroscopy and single molecule methods such as AFM. It allowed us to identify that a protein, lamin A, forms chromatin loops thereby restricting the chromatin dynamics in the whole nucleus volume. Based on the results, we conclude that the organization of the DNA in the nucleus is based on a “DNA matrix”, a structure that we describe here for the first time. The experimental methods we use necessitate the use of biophysical modeling based on Smoluchowski equation, modified diffusion equations and polymer physics. I will describe the problem, the methods we use, the results and the conclusions as described above.

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GlucoCEST - From Quantification to numerical optimization and in vivo application

Date:

31

Thursday

May

2018

Lecture / Seminar

Time: 09:30-10:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Moritz Zaiss

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: For the aim of using glucose as a biodegradable MRI contrast agent, employing ... Read more For the aim of using glucose as a biodegradable MRI contrast agent, employing chemical exchange saturation transfer of its hydroxyl protons to water, it is necessary to quantify the individual hydroxyl exchange rates. In the intermediate to fast exchange regime this can be done using multiple-power CEST spectra acquisition of glucose solutions at physiological conditions, and extracting the exchange rates by a Bloch-McConnell fit. With this information presaturation and sequence parameter optimization can be performed in silico, and translated to glucoCEST sequence application in vivo at 3 T, 7 T, and 9.4 T. First data of glucoCEST at 7 T and 9.4 T in braintumors will be presented.

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UCSC Genome Browser: New features and hidden features Q & A session

Date:

17

Thursday

May

2018

Lecture / Seminar

Time: 10:00

Location: Max and Lillian Candiotty Building

Lecturer: Kate Rosenbloom

Organizer: Department of Life Sciences Core Facilities

Contact: shifra.ben-dor@weizmann.ac.il

Details: Kate Rosenbloom has been a UCSC browser engineer since 2003, working to integrat ... Read more

Abstract: For the past several years, a main focus of the UCSC browser group has been deve ... Read more For the past several years, a main focus of the UCSC browser group has been developing data organization and display features in response to the massive expansion of data quantity and variety in the genomics field. There will be a short talk covering recent features motivated by these issues, highlighting two of the newest - the Track Collection Builder tool, and the new pairwise interaction ('interact') track type. This will be followed by a quick tour through some not-so-obvious browser features such as exon-only display, isoform hiding, highlights, and track reordering. There will be ample time for questions, reflections and suggestions about browser features and data.

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Developmental Club Series 2017-2018

Date:

16

Wednesday

May

2018

Lecture / Seminar

Time: 10:00

Title: Imaging and Regulation of the Cellular Events that Shape the Vertebrate Embryo

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Prof. Jerome Gros

Organizer: Department of Molecular Genetics

Contact: ingrid.lehrer@weizmann.ac.il

Synaptic dynamics in mouse visual cortex

Date:

15

Tuesday

May

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Tara Keck

Organizer: Department of Brain Sciences

Abstract: Homeostatic synaptic scaling is thought to occur cell-wide, but recent evidence ... Read more Homeostatic synaptic scaling is thought to occur cell-wide, but recent evidence suggests this form of stabilizing plasticity can be implemented more locally in reduced preparations. To investigate the spatial scales of plasticity in vivo, we used repeated two-photon imaging in mouse visual cortex after sensory deprivation to measure TNF-α dependent increases in spine size as a proxy for synaptic scaling in vivo in both excitatory and inhibitory neurons. We found that after sensory deprivation, increases in spine size are restricted to a subset of dendritic branches, which we confirmed using immunohistochemistry. We found that the dendritic branches that had individual spines that increased in size following deprivation, also underwent a decrease in spine density. Within a given dendritic branch, the degree of spine size increases is proportional to recent spine loss within that branch. Using computational simulations, we show that this compartmentalized form of synaptic scaling better retained the previously established input-output relationship in the cell, while restoring activity levels. We then investigated the relationship between new spines that form after this spine loss and strengthening and find that their spatial positioning facilitates strengthening of maintained synapses.

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Life Science Colloquium

Date:

14

Monday

May

2018

Colloquium

Time: 11:00-12:00

Title: Imaging immunity

Location: Dolfi and Lola Ebner Auditorium

Lecturer: Prof. Hidde Ploegh

Organizer: Life Sciences

Contact: daphna.freeman@weizmann.ac.il

In vivo identification of brain structures functionally involved in spatial learning and strategy switch

Date:

13

Sunday

May

2018

Lecture / Seminar

Time: 10:00

Location: Nella and Leon Benoziyo Building for Brain Research

Lecturer: Dr. Suellen DeAlmeida-Correa

Organizer: Department of Brain Sciences

Details: Benoziyo Brain Research Building Room 113 Host: Dr.Ivo Spiegel ivo.spiegel@we ... Read more

Abstract: Spatial learning is a complex behavior which includes, among others, encoding of ... Read more Spatial learning is a complex behavior which includes, among others, encoding of space, sensory and motivational processes, arousal and locomotor performance. Today, our view on spatial navigation is largely hippocampus-centrist. Less is known about the involvement of brain structures up- and downstream, or out of this circuit. Here, we provide the fist in vivo assessment of the neural matrix underlying spatial learning, using functional manganese-enhanced MRI (MEMRI) and voxel-wise whole brain analysis. Mice underwent place-learning (PL) vs. response-learning (RL) in the water cross maze (WCM) and its readout was correlated to the Mn2+ contrasts. Thus, we identified structures involved in spatial learning largely overlooked in the past, due to methods focused on region of interest (ROI) analyses. Add-on experiments pointed to bias in Mn2+ accumulati! on towards projection terminals, suggesting that our mapping was mostly formed by projection sites of the originally activated structures. This is corroborated by in-depth analysis of MEMRI data after WCM learning showing mostly downstream targets of the hippocampus. These differ between fornical afferences from vCA1 and direct innervation from dCA1/iCA1 (for PL), and structures along the longitudinal association bundle originating in vCA1 (for RL). To elucidate the pattern of Mn2+ accumulation seen on the scans we performed c-fos expression analyses following learning in the WCM. This helped us identify the structures initially activated during spatial learning and its underlying connectivity to establish the matrix. Finally, to test the causal involvement of these structures we inhibited them (through DREADDs) while mice performed in the WCM task. We also focused on the causal involvement of the mPFC-HPC circuit on strategy switch during WCM learning. We believe that this study might shed light into new brain structures involved in spatial learning and strategy switch and complement the current knowledge on these circuits’ connectivity. Moreover, we elucidated some functional mechanisms of MEMRI, clarifying the interpretation of data obtained with this method and its possible future applications.

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Deciphering the cellular copper trafficking mechanism in order to develop a new generation of antibiotics and biomarkers

Date:

10

Thursday

May

2018

Lecture / Seminar

Time: 09:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Sharon Ruthstein

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: In the last couple of years, my lab has been exploring the cellular copper cyc ... Read more In the last couple of years, my lab has been exploring the cellular copper cycle in eukaryotic and prokaryotic systems using Electron Paramagnetic Resonance (EPR) spectroscopy. While most of the proteins involved in the copper cycle are believed to be known, as well as some of the crystal structures, there is still lack of information on the kinetic and the transfer mechanism of the copper in the cellular environment. Since dysfunction of the copper regulation system can lead to neurological diseases and to the cell death, it is essential to understand every little detail in the copper ycle to be able to control it according to specific needs EPR has become a powerful tool for studying complex dynamic biological systems since it is not limited to the protein size and does not require crystallization. Hence, the biological system can be studied in solution, lipids, and even the cellular environment. In our group, we are applying various EPR measurements together with computations, biochemistry experiments, CD and NMR to identify the copper binding sites, as well as to understand how one protein in the cycle coordinated to another protein to transfer the metal ion. We target the conformational changes that occur in each protein, and we aim to gain also kinetic data on the transfer mechanism. In this talk, I will present our results on the copper transfer mechanism in the human and E.coli cells. I will also demonstrate how basic understanding of the function of these systems can assist us in designing new class of antibiotics and biomarkers for hypoxic systems.

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Atlases of structure-function relationships in small motifs: the limits of modularity

Date:

08

Tuesday

May

2018

Lecture / Seminar

Time: 14:00

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Dr. James Sharpe

Organizer: Azrieli Institute for Systems Biology

Contact: Ingrid.lehrer@weizmann.ac.il

Abstract: Abstract: I will discuss our work on visualizing “topology atlases” which a ... Read more Abstract: I will discuss our work on visualizing “topology atlases” which act as a map of possible circuit designs for small 3-node regulatory motifs. These can help in understanding the relationship between a circuit's structure and its function, but how is this relationship affected if the circuit must perform multiple distinct functions within the same organism? In particular, to what extent do multi‐functional circuits contain modules which reflect the different functions? We computationally surveyed a range of bi‐functional circuits which show no simple structural modularity: They can switch between two qualitatively distinct functions, while both functions depend on all genes of the circuit. Our analysis revealed two distinct classes: hybrid circuits which overlay two simpler mono‐functional sub‐circuits within their circuitry, and emergent circuits, which do not. In this second class, the bi‐functionality emerges from more complex designs which are not fully decomposable into distinct modules and are consequently less intuitive to predict or understand. These non‐intuitive emergent circuits are just as robust as their hybrid counterparts, and we therefore suggest that the common bias toward studying modular systems may hinder our understanding of real biological circuits. Relevant papers: 1. A spectrum of modularity in multi-functional gene circuits. Jiménez A, Cotterell J, Munteanu A, Sharpe J. (2017) Mol Syst Biol 13(4):925. doi: 10.15252/msb.20167347 http://msb.embopress.org/content/13/4/925 2. An atlas of gene regulatory networks reveals multiple three-gene mechanisms for interpreting morphogen gradients. Cotterell J, Sharpe J. (2010) Mol Syst Biol 6:425. doi: 10.1038/msb.2010.74 http://msb.embopress.org/content/6/1/425 Bio: James Sharpe was originally captivated by computer programming, but upon learning about the digital nature of the genetic code, chose to study Biology for his undergraduate degree at Oxford University (1988-1991). He then did his PhD on the genetic control of embryo development at NIMR, London (1992-1997) and in parallel started writing computer simulations of multicellular development. During his post-doc in Edinburgh, he began modelling the dynamics of limb development, and also invented a new optical imaging technology called Optical Projection Tomography (OPT), which is dedicated to imaging specimens too large for microscopy - tissues and organs. In 2006 he moved to Barcelona, becoming a senior group leader at the Centre for Genomic Regulation, and focusing on a systems biology approach to modelling limb development – combining experimentation with computer modelling. In this way the group demonstrated that the signalling proteins which pattern the fingers during embryogenesis, act as a Turing reaction-diffusion system. In 2011 he became the coordinator of the Systems Biology Program, and in 2017 was recruited to EMBL as Head of the new Barcelona outstation on Tissue Biology and Disease Modelling.

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G-INCPM Special Seminar - Dr. Daniel Liber, Business Development Manager, Automation, Takara Bio Europe - "SMARTer ICELL8: The Open Platform for Single-Cell Genomics"

Date:

01

Tuesday

May

2018

Lecture / Seminar

Time: 14:30-15:30

Location: Gerhard M.J. Schmidt Lecture Hall

Organizer: Department of Biomolecular Sciences

Contact: shlomit.gilad@weizmann.ac.il

Abstract: Single-cell genomics allows to understand cellular heterogeneity at an unprecede ... Read more Single-cell genomics allows to understand cellular heterogeneity at an unprecedented resolution. The SMARTer ICELL8 Single-Cell System gives more control in the experimental design, more confidence in the data and unique workflow flexibilities while reducing the experimental costs. The ICELL8 multi-nanowell chip can isolate hundreds of cells from multiple samples at once, from the very small, like nuclei from frozen tissues, to the very large, like primary cardiomyocytes and spheroids. The SMARTer ICELL8 has been validated for multiple applications, including gene expression analysis, full-length transcriptomics, T-Cell Receptor sequencing and ATAC-seq, which have been developed by Takara Bio’s R&D or ICELL8 users.

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Special Seminar:Tightly Linking Chemistry and Biology through Covalent Bonds

Date:

25

Wednesday

April

2018

Lecture / Seminar

Time: 11:00-12:30

Location: Helen and Milton A. Kimmelman Building

Lecturer: Prof. Xiaoguang Lei

Organizer: Department of Molecular Chemistry and Materials Science

Abstract: Biological interactions are always weak and transient, which present significant ... Read more Biological interactions are always weak and transient, which present significant challenges for us to dissecting these processes! Therefore, biocompatible covalent bond formations (or so called ligations) may greatly facilitate the studies of these complex biological processes through turning the week and transient interactions to the strong covalent interactions. In this lecture, I will present several examples from our laboratory about how we use novel covalent small molecule probes or biocompatible ligation chemistry to dissect fundamental cellular events such as programmed cell death as well as to explore the complex protein structures and protein-protein interactions. In particular, I will focus on an emerging technology we have been actively developing over the past 5 years, chemical cross-linking of proteins coupled with mass spectrometry analysis (CXMS). I will demonstrate that how novel bioconjugation chemistry enable the new advancement of CXMS and how we apply CXMS as a powerful tool in combination of X-ray crystallography or Cryo-electron microscopy to elucidate the complex protein machinery structures and systematically map protein-protein interactions.

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"Quantitative chemical imaging in vivo"

Date:

23

Monday

April

2018

Colloquium

Time: 11:00-12:15

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Yamuna Krishnan

Organizer: Faculty of Chemistry

Abstract: Department of Chemistry & Grossman Institute of Neuroscience and Quantitative Bi ... Read more Department of Chemistry & Grossman Institute of Neuroscience and Quantitative Biology The University of Chicago DNA can be self-assembled into molecularly precise, well-defined, synthetic assemblies on the nanoscale, commonly referred to as designer DNA nanodevices. My lab creates synthetic, chemically responsive, DNA-based fluorescent probes. (1) In 2009 my lab discovered that these designer nanodevices could function as fluorescent reporters to quantitatively image ions in real time in living systems. (2,3) Until this innovation, it was not at all obvious whether such DNA nanodevices could function inside a living cell without being interfered with, or interfering with, the cells own networks of DNA control (4). In this talk I will discuss unpublished work on how we have expanded this technology from ion imaging (5,6) to now quantitatively imaging reactive species as well as enzymatic cleavage with sub-cellular spatial resolution in vivo. References: 1. Chakraborty, K., et al., Nucleic acid based nanodevices in biological imaging. Ann. Rev. Biochem., 2016 85, 349-373. 2. Modi, S., et al. A DNA nanomachine that maps spatial and temporal pH changes in living cells. Nature Nanotechnology, 2009, 4, 325-330. 3. Modi, S., et al. Two DNA nanomachines map pH of intersecting endocytic pathways. Nature Nanotechnology, 2013, 8, 459-467. 4. Surana, S., et al. Designing DNA nanodevices for compatibility with the immune system of higher organisms. Nature Nanotechnology, 2015, 10, 741-747. 5. Saha, S., et al. A pH-insensitive DNA nanodevice quantifies chloride in organelles of living cells. Nature Nanotechnology, 2015, 10, 645-651. 6. Chakraborty, K., et al., High lumenal chloride in the lysosome is critical for lysosome function. eLife, 2017, 6, e28862. 7. Dan, K. et al., DNA nanodevices map enzymatic activity in vivo. 2018 (in revision). 8. Thekkan, S. et al A DNA-based fluorescent reporter maps HOCl dynamics in the maturing phagosome. 2018 (submitted)

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Collective Sensing and Decision-Making in Animal Groups: From Fish Schools to Primate Societies

Date:

17

Tuesday

April

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Iain D. Couzin

Organizer: Department of Brain Sciences

Abstract: Understanding how social influence shapes biological processes is a central chal ... Read more Understanding how social influence shapes biological processes is a central challenge in contemporary science, essential for achieving progress in a variety of fields ranging from the organization and evolution of coordinated collective action among cells, or animals, to the dynamics of information exchange in human societies. Using an integrated experimental and theoretical approach I will address how, and why, animals exhibit highly-coordinated collective behavior. I will demonstrate new imaging and virtual reality (VR) technology that allows us to reconstruct (automatically) the dynamic, time-varying sensory networks by which social influence propagates in groups. This allows us to identify, for any instant in time, the most socially-influential individuals, to reveal the (counterintuitive) relationship between network structure and social contagion, and to predict the magnitude of complex behavioural cascades within groups before they actually occur. By investigating the coupling between spatial and information dynamics in groups we also demonstrate that emergent problem solving is the predominant mechanism by which mobile groups sense, and respond to complex environmental gradients. Finally I will reveal the critical role uninformed, or unbiased, individuals play in effecting fast, democratic consensus decision-making in collectives, and will test these predictions with experiments involving schooling fish and wild baboons, as well as suggest how such results may relate to decision-making in neural systems.

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Is mesoscopic resolution for BOLD fMRI enough? MR Imaging of electrical properties as a more direct probe of neuronal activation

Date:

15

Sunday

April

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Dr. Rita Schmidt

Organizer: Department of Brain Sciences

Details: Host: Prof. Alon Chen alon.chen@weizmann.ac.il tel: 4490 For accessibility iss ... Read more

Abstract: Current state of the art ultra-high field MRI scanners have already achieved sub ... Read more Current state of the art ultra-high field MRI scanners have already achieved submillimeter resolution in 3D imaging of the human brain. Studies of the functional activity in the brain - by Blood Oxygen Level Dependent (BOLD) technique - have utilized this capability to observe mesoscopic (200-300µm) structures in humans. However, does BOLD tell us the full story? With current state of the art in mind, we are looking for the next step forward to better understand the brain physiology. I will share an on-going research on the mapping of electrical properties, aimed at studying functional activity in the human brain and offering a more direct probe of neuronal activity. The research includes a new computational technique for estimating electrical properties from an MR experiment, as well as the implementation of fast acquisition techniques. I will also show a correlation between changes in the electrical conductivity and basic activation paradigms (visual or motor) demonstrating faster response versus BOLD signal.

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Cell Penetration and Membrane Fusion: Two Sides of the Same Coin

Date:

10

Tuesday

April

2018

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Pavel Jungwirth

Organizer: Department of Biomolecular Sciences

Abstract: Cell penetrating peptides have a unique potential for targeted drug delivery, th ... Read more Cell penetrating peptides have a unique potential for targeted drug delivery, therefore, mechanistic understanding of their membrane action has been sought since their discovery over 20 years ago. While ATP-driven endocytosis is known to play a major role in their internalization, there has been also ample evidence for the importance of passive translocation for which the direct mechanism, where the peptide is thought to directly pass through the membrane via a temporary pore, has been widely advocated. In this talk, I will question this view and demonstrate that arginine-rich cell penetrating peptides can instead enter vesicles and cells by inducing multilamellarity and fusion, analogously to the action of calcium ions. The molecular picture of this penetration mode, which differs qualitatively from the previously proposed direct mechanism, is provided by molecular dynamics simulations. In addition, the kinetics of vesicle agglomeration and fusion by nonaarginine, nonalysine, and calcium ions are documented in real time by fluorescence techniques and the induction of multilamellar phases in vesicles and cells is revealed both via electron microscopy and fluorescence spectroscopy. We thus show that the newly identified passive cell penetration mechanism is analoguous to vesicle fusion induced by calcium ions, demonstrating that the two processes are of a common mechanistic origin.

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"Inorganic nanotubes and fullerene-like nanoparticles at the crossroad between materials science and nanotechnology and their applications"

Date:

09

Monday

April

2018

Colloquium

Time: 11:00-12:15

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Reshef Tenne

Organizer: Faculty of Chemistry

Abstract: After almost 100 years of research inorganic layered (2D) materials, like MoS2, ... Read more After almost 100 years of research inorganic layered (2D) materials, like MoS2, are currently used as catalysts, lubricants, and perhaps most importantly in rechargeable Li- ion batteries. After a short briefing on the history of 2D materials research,1 the concepts which lead to the first synthesis of hollow-cage nanostructures, including nanotubes (INT) and fullerene-like (IF) nanoparticles from 2D compounds, will be presented. The progress with the high-temperature synthesis and characterization of new inorganic nanotubes (INT) and fullerene-like (IF) nanoparticles (NP) will be presented. In particular, the synthesis and structure of nanotubes from the ternary “misfit” layered compounds (MLC), like LnS-TaS2 (Ln= La, Ce, Gd, Ho, Er), CaCoO-CoO2 and numerous other MLC were elucidated. More recently nanotubes (and nanoscrolls) from quaternary MLC were reported. Major progress has been achieved in elucidating the structure of INT and IF using advanced microscopy techniques, like aberration corrected TEM and related techniques. Mechanical, electrical and optical measurements of individual WS2 nanotubes reveal their unique quasi-1D characteristics. This analysis demonstrate their different behavior compared to the bulk phase. Applications of the IF/INT as superior solid lubricants and for reinforcement of variety of polymers and light metal alloys was demonstrated. Few recent studies indicate that this brand of nanoparticles is less toxic than most nanoparticles. With expanding product lines, manufacturing and sales, these nanomaterials are gradually becoming an industrial commodity. 1. L. Panchakarla, B. Visic and R. Tenne, “Perspective”, J. Am. Chem. Soc. 2017, 139, 12865-12878.

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Controlling Nucleic-Acid-Based Processes by Light

Date:

28

Wednesday

March

2018

Lecture / Seminar

Time: 10:00-11:00

Location: Nella and Leon Benoziyo Building for Biological Sciences

Lecturer: Prof. Andreas Moglich

Organizer: Department of Biomolecular Sciences

Abstract: Sensory photoreceptor proteins underpin sensation of incident light and mediate ... Read more Sensory photoreceptor proteins underpin sensation of incident light and mediate numerous organismal adaptations of behavior, lifestyle and physiology. Photoreceptors excel in the reversibility, noninvasiveness and spatiotemporal precision of the biological responses they elicit. For exactly these benefits, photoreceptors have found frequent use as light-gated actuators for the control by light of intracellular processes and parameters, an application area known as optogenetics. The engineering of novel photoreceptors, that is, protein actuators with custom-tailored light-gated function, has greatly expanded the repertoire provided by natural photoreceptors and has thereby unlocked additional areas for optogenetic intervention. By recombining blue-light-sensitive light-oxygen-voltage (LOV) photosensor modules with effector modules of desired output activity, we have generated several implements for the optogenetic control of nucleic-acid-based biological processes, e.g., endonuclease cleavage and gene expression. Biochemical analyses of structure, function and signaling mechanism of sensory photoreceptors unravel the molecular bases for light-dependent allostery and inform the engineering of additional representatives.

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Visualizing Synapse Formation and Elimination in vivo

Date:

27

Tuesday

March

2018

Lecture / Seminar

Time: 12:30

Location: Gerhard M.J. Schmidt Lecture Hall

Lecturer: Prof. Elly Nedivi

Organizer: Department of Brain Sciences

Details: Host: Dr.Ivo Spiegel ivo.spiegel@weizmann.ac.il tel: 4415 For assistance with ... Read more

Abstract: The introduction of two-photon microscopy for in vivo imaging has opened the doo ... Read more The introduction of two-photon microscopy for in vivo imaging has opened the door to chronic monitoring of individual neurons in the adult brain and the study of structural plasticity mechanisms at a very fine scale. Perhaps the biggest contribution of this modern anatomical method has been the discovery that even across the stable excitatory dendritic scaffold there is significant capacity for synaptic remodeling, and that synaptic structural rearrangements are a key mechanism mediating neural circuit adaptation and behavioral plasticity in the adult. To monitor the extent and nature of excitatory and inhibitory synapse dynamics on individual L2/3 pyramidal neurons in mouse visual cortex in vivo, we labeled these neurons with a fluorescent cell fill as well as the fluorescently tagged synaptic scaffolding molecules, Teal-Gephyrin to label inhibitory synapses, and mCherry-PSD-95 to label excitatory synapses. We simultaneously tracked the daily dynamics of both synapse types using spectrally resolved two-photon microscopy. We found that aside from the lower magnitude of excitatory synaptic changes in the adult, as compared to inhibitory ones, excitatory synapse dynamics appear to follow a different logic than inhibitory dynamics. While excitatory dynamics seem to follow a sampling strategy to search for and create connections with new presynaptic partners, inhibitory synapse dynamics likely serve to locally modulate gain at specific cellular locales.

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Frontiers in Magnetic Resonance Imaging

Date:

27

Tuesday

March

2018

Conference

Time: 08:00

Location: David Lopatie Conference Centre

Contact: tali.scherf@weizmann.ac.il

Assessing Hot-Electron Dynamics in Nanoparticles with Transient Absorption Spectroscopy - Nanoparticle Interactions and Potential Implications for Catalysis

Date:

21

Wednesday

March

2018

Lecture / Seminar

Time: 11:00-12:00

Location: Perlman Chemical Sciences Building

Lecturer: Prof. Holger Lange

Organizer: Department of Molecular Chemistry and Materials Science

The annual meeting of the Israeli Live Imaging Forum Conference website

Abstract: Proximal metallic and semiconductor nanocrystals can interact in various ways. ... Read more Proximal metallic and semiconductor nanocrystals can interact in various ways. Time-resolved photoluminescence allows to address interaction dependeces, which happen on picosecond timescales. We were able to reveal an unanticipated dependence on the gold nanoparticle size. Looking deeper into the gold afterwards leads to the plasmon dynamics, for example hot-electron generation, which is happening faster than picoseconds. We found dependences of the hot electron generation on the excitation conditions which will allow more systematic studies of the plasmon-assisted catalysis

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Special Seminar: "Single molecule, real-time (SMRT) sequencing - advanced genomics with long read sequencing"

Date:

15

Thursday

March

2018

Lecture / Seminar

Time: 10:00-11:00

Location: Max and Lillian Candiotty Building

Lecturer: Dr. Swati Ranade

Organizer: Department of Life Sciences Core Facilities

Contact: Hadas.Keren-Shaul@weizmann.ac.il

The annual meeting of the Israeli Live Imaging Forum

Date:

15

Thursday

March

2018

Conference

Time: 08:00

Location: David Lopatie Conference Centre

Contact: ronen.alon@weizmann.ac.il

“Imaging the Future: How Neuroimaging Might Better People’s Lives”

Date:

06

Tuesday

March

2018

Lecture / Seminar

Time: 12:30

Location: Arthur and Rochelle Belfer Building for Biomedical Research

Lecturer: Prof. John Gabrieli

Organizer: Department of Brain Sciences