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Date:18MondayMarch 2024Colloquia
Atom-Probe Tomography and its Myriad Applications in Chemistry
More information Time 11:00 - 12:15Location Gerhard M.J. Schmidt Lecture HallLecturer Prof. David N. Seidman
McCormick School of Engineering, Northwestern UniversityOrganizer Department of Molecular Chemistry and Materials ScienceHomepage Contact Abstract Show full text abstract about atom-probe tomograph (APT) can dissect a nanotip shaped spec...» atom-probe tomograph (APT) can dissect a nanotip shaped specimen (radius <50 nm) atom-byatom
and by atomic plane-by-plane, and then the dissected volume can be reconstructed from the
positions of the atoms in three-dimensions (3-Ds), with atomic-scale resolution plus assigning an
elemental or isotopic identity to each atom with a detection efficiency of ~80% (E. W. Mueller, J. A.
Panitz, S. B. McLane, 1968). To be specific an APT consists of a field-ion microscope (FIM), which
one uses to observe individual atoms on the surface of a nanotip with atomic resolution ( E. W. Mueller
and Bahadur, 1956).plus a special time-of-flight (TOF) mass spectrometer to determine the mass-tocharge
state ratio (m/n) of each charged field-evaporated atomic or molecular ion: the nanotip is at a
positive potential with respect to ground. In a modern APT a picosecond ultraviolet (UV) laser,
operating in a pulsed mode, is utilized to thermally activate field-evaporated atoms from the surface of
a nanotip as positively charged ions. The ions are detected using a microchannel plate (MCP) detector,
with a gain of 107, which serves as the primary detector of the evaporated ions, which, in turn, yields
their m/n values from their TOFs. Behind the primary detector is a secondary detector, which yields
the 2-D positions of the field-evaporated ions in different {hkl} planes on the surface of a nanotip,
which to first order is a highly faceted hemisphere. With continuing pulsed field-evaporation the atoms
in the bulk of a nanotip are sequentially detected, thereby yielding the 3rd dimension and hence the
name atom-probe tomograph (APT). In addition to the functional principles of an APT, select research
applications are presented. -
Date:18MondayMarch 2024Lecture
Foundations of Computer Science Seminar
More information Time 11:15 - 12:15Title Toward Better Depth Lower Bounds: A KRW-like theorem for Strong CompositionLocation Jacob Ziskind Building
Room 155Lecturer Or Meir
University of HaifaOrganizer Department of Computer Science and Applied Mathematics
SeminarContact Abstract Show full text abstract about One of the major open problems in complexity theory is provi...» One of the major open problems in complexity theory is proving super-logarithmic lower bounds on the depth of circuits. Karchmer, Raz, and Wigderson (Computational Complexity 5(3/4), 1995) suggested approaching this problem by proving that depth complexity of a composition of two functions is roughly the sum of their individual depth complexities. They showed that the validity of this conjecture would imply the desired lower bounds.
The intuition that underlies the KRW conjecture is that composition should behave like a "direct-sum problem", in a certain sense, and therefore the depth complexity of the composition should be the sum of the individual depth complexities. Nevertheless, there are two obstacles toward turning this intuition into a proof: first, we do not know how to prove that the composition must behave like a direct-sum problem -
Date:19TuesdayMarch 2024Conference
STATISTICAL MECHANICS DAY XV
More information Time 08:00 - 08:00Location Nella and Leon Benoziyo Physics Library
Library RoomChairperson Oren RazOrganizer Department of Physics of Complex SystemsHomepage Contact -
Date:19TuesdayMarch 2024Conference
Israeli RNA Meeting 2023 in memory of Prof. Yossi Sperling
More information Time 08:30 - 16:00Location The David Lopatie Conference CentreChairperson Schraga SchwartzOrganizer Abisch-Frenkel RNA Therapeutics Center , Azrieli Institute for Systems BiologyContact -
Date:19TuesdayMarch 2024Lecture
iSCAR Breakfast Seminar
More information Time 09:00 - 10:00Location Max and Lillian Candiotty Building
AuditoriumLecturer Dr. Yaniv Elkouby
From the stem cell to the follicle: Unpredicted cellular machineries in oocyte production and reproductionOrganizer Department of Immunology and Regenerative BiologyContact -
Date:19TuesdayMarch 2024Lecture
Dimensionality bottleneck uncovers simple action selection rules in hunting zebrafish
More information Time 12:30 - 13:30Location Gerhard M.J. Schmidt Lecture HallLecturer Dr. Lilach Avitan
Edmond and Lily Safra Center for Brain Sciences The Hebrew University of JerusalemOrganizer Department of Brain SciencesContact Details Show full text description of Host: Dr. Yoav Livneh yoav.livneh@weizmann.ac.il tel: 6230...» Host: Dr. Yoav Livneh yoav.livneh@weizmann.ac.il
tel: 6230
For accessibility issues:naomi.moses@weizmann.ac.ilAbstract Show full text abstract about Animal movements are complex, high-dimensional, and lead to ...» Animal movements are complex, high-dimensional, and lead to many different consequences. Thus, efficiently quantifying the behavior and uncovering the underlying representation used by the animal pose a great challenge. Tracking freely behaving zebrafish larvae using a high-speed camera and analyzing their movements, we reveal that zebrafish movements can be described using exactly two parameters. Mapping all possible two-dimensional movement representations, we identified the representation used by the fish. We show that fish do not trivially represent distance and angles as separate parameters, but rather mix them nonlinearly. Moreover, when hunting, this specific nonlinear relation depends on the prey angle and further dictates a particular set of potential movements. These results uncover, for the first time, the underlying action selection principles of hunting behavior, suggesting that behind this seemingly complex behavior there is a simple and low-dimensional process.
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Date:19TuesdayMarch 2024Lecture
New approaches to glycan synthesis and glycan-based biosensing
More information Time 14:00 - 15:00Location Gerhard M.J. Schmidt Lecture HallLecturer Prof. Mattan Hurevich
Institute of Chemistry Hebrew UniversityOrganizer Department of Chemical and Structural BiologyContact -
Date:20WednesdayMarch 2024Lecture
Employing the Hegelian Aufhebung Principle for Predicting New Catalytic Pathways
More information Time 11:00 - 12:00Location Perlman Chemical Sciences Building
Room 404Lecturer Prof. Anatoly Frenkel
Stony Brook University and Brookhaven National LaboratoryOrganizer Department of Molecular Chemistry and Materials ScienceContact Abstract Show full text abstract about Understanding mechanisms of work for a wide range of applied...» Understanding mechanisms of work for a wide range of applied nanomaterials begins with identifying “active units” in operating conditions, zooming in on the “active sites” and ends with a model explaining their role for functioning of the material or device. There are two main hurdles that we are particularly interested in overcoming: 1) heterogeneity of active species and sites and 2) their dynamics that can be directly responsible for their mechanisms. One possible method, ideally suitable for capitalizing on these challenges for rational design of new catalytic pathways, is the Aufhebung (sublation) principle from the Hegelian dialectics. It describes the process of advancing knowledge by integrating the two opposites: the thesis and antithesis. We adopt this principle to leverage the inherent heterogeneity of catalytic active species and active sites in metal catalysts for understanding and predicting new catalytic pathways for CO and CO2 conversion reactions. Starting with atomically dispersed (the thesis) Pt on ceria support, we use multimodal, operando characterization for monitoring formation of nanoparticles (the antithesis), identify reaction active species and unique active sites at the metal-support interface. With this knowledge, we design the “single-atoms” catalysts (synthesis) possessing the same active sites and enhanced stability in reaction conditions. I will highlight the role of oxygen vacancies for enhancing the dynamicity of Pt atoms and opening new reaction pathways for direct and reverse water gas shift reactions and CO oxidation reaction.
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Date:21ThursdayMarch 2024Lecture
Special Guest Seminar with Prof. Eugene V. Koonin
More information Time 11:00 - 12:00Title "Global structure and evolution of the virosphere"Location Arthur and Rochelle Belfer Building for Biomedical Research
Botnar AuditoriumLecturer Prof. Eugene V. KooninOrganizer Department of Molecular GeneticsContact Abstract Show full text abstract about Viruses and virus-like mobile genetic elements are ubiquitou...» Viruses and virus-like mobile genetic elements are ubiquitous parasites (and sometime symbionts) of all cellular life forms and the most abundant biological entities on earth. The recent, unprecedented advances of comparative genomics and metagenomics have led to the discovery of diverse novel groups of viruses and a rapid expansion of the chartered region of the virosphere. These discoveries provide for a vastly improved understanding of the evolutionary relationships within the virosphere. Arguably, we are approaching the point when the global architecture of the virus world can be outlined in its entirety, and the key evolutionary events in each of its domains can be reconstructed. I will present such an outline of the global organization of the virosphere and the corresponding megataxonomy, including 6 distinct virus realms, that has been recently approved by the International Committee on Taxonomy of Viruses, as well as some new candidates. The expansion of the prokaryotic virosphere that is being shown to include many groups of viruses, particularly, those with RNA genomes, previously thought to be eukaryote-specific, will be emphasized. I will further discuss the position of viruses within the wider space of replicators and the recent dramatic expansion of the “alternative virosphere” that includes viroids and diverse viroid-like viruses that seem to have evolved on multiple, independent occasions. -
Date:21ThursdayMarch 2024Colloquia
Physics Colloquium
More information Time 11:15 - 12:30Title Fractional statistics of anyons in mesoscopic collidersLocation Edna and K.B. Weissman Building of Physical Sciences
AuditoriumLecturer Prof. Gwendal Fève
Sorbonne University , Paris, FranceOrganizer Department of Condensed Matter PhysicsContact Details Show full text description of Refreshments will be served at 11:00...» Refreshments will be served at 11:00Abstract Show full text abstract about In three-dimensional space, elementary particles are divided...» In three-dimensional space, elementary particles are divided between fermions and bosons according to the properties of symmetry of the wave function describing the state of the system when two particles are exchanged. When exchanging two fermions, the wave function acquires a phase, φ=π. On the other hand, in the case of bosons, this phase is zero, φ=0. This difference leads to deeply distinct collective behaviors between fermions, which tend to exclude themselves, and bosons which tend to bunch together. The situation is different in two-dimensional systems which can host exotic quasiparticles, called anyons, which obey intermediate quantum statistics characterized by a phase φ varying between 0 and π [1,2].
For example in the fractional quantum Hall regime, obtained by applying a strong magnetic field perpendicular to a two-dimensional electron gas, elementary excitations carry a fractional charge [3,4] and have been predicted to obey fractional statistics [1,2] with an exchange phase φ=π/m (where m is an odd integer). Using metallic gates deposited on top of the electron gas, beam-splitters of anyon beams can be implemented. I will present how the fractional statistics of anyons can be revealed in collider geometries, where anyon sources are placed at the input of a beam-splitter [5,6]. The partitioning of anyon beams is characterized by the formation of packets of anyons at the splitter output. This results in the observation of strong negative correlations of the electrical current, which value is governed by the anyon fractional exchange phase φ [5,7].
[1] B. I. Halperin, Phys. Rev. Lett. 52, 1583–1586 (1984).
[2] D. Arovas, J. R. Schrieffer, F. Wilczek, Phys. Rev. Lett. 53, 722–723 (1984).
[3] R. de Picciotto et al., Nature 389, 162–164 (1997).
[4] L. Saminadayar, D. C. Glattli, Y. Jin, B. Etienne, Phys. Rev. Lett. 79, 2526–2529 (1997)
[5] B. Rosenow, I. P. Levkivskyi, B. I. Halperin, Phys. Rev. Lett. 116, 156802 (2016).
[6] H. Bartolomei et al. Science 368, 173-177 (2020).
[7] Lee, JY.M., Sim, HS, Nature Communications 13, 6660 (2022).
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Date:21ThursdayMarch 2024Lecture
Chemistry and the Information beyond the Genome Sequence
More information Time 14:00 - 15:00Location Gerhard M.J. Schmidt Lecture HallLecturer Prof. Andreas Marx
Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz GermanyOrganizer Department of Chemical and Structural BiologyContact -
Date:21ThursdayMarch 2024Lecture
The Golden Approach for Overcoming Bio-Barriers: Delivering Nanomedicine to Brain and Beyond
More information Time 14:00 - 15:00Location Max and Lillian Candiotty Building
AuditoriumLecturer Prof. Rachela Popovtzer
Faculty of Engineering and The Institute of Nanotechnology and Advanced Materials. Bar-Ilan University, IsraelOrganizer Dwek Institute for Cancer Therapy Research
Cancer Research ClubContact Details Show full text description of Meeting URL: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6K...» Meeting URL: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09
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Date:21ThursdayMarch 2024Lecture
Allosteric modulation of protein kinase A in individuals affected by NLPD-PKA , a neurodegenerative disease in which the RIß-L50R variant is expressed
More information Time 15:00 - 16:00Location Nella and Leon Benoziyo Building for Biological Sciences
AuditoriumLecturer Dr. Ronit Ilouz
Molecular and Cellular Mechanisms of Neurological Diseases, Bar-Ilan UniversityOrganizer Department of Biomolecular SciencesContact Details Show full text description of Protein Kinase A (PKA) plays a crucial role in regulating ne...» Protein Kinase A (PKA) plays a crucial role in regulating neuronal functions, and its dysregulation has been implicated in neurodegenerative diseases. Despite extensive research on isoform-specific PKA holoenzymes, consisting of regulatory subunit dimers and catalytic subunits, the pathological consequences of impaired PKA holoenzyme assembly have remained unexplored.
In this presentation, I will highlight a novel molecular mechanism underlying a PKA-dependent neurodegenerative disease, as well as the initial evidence of a mutation leading to PKA holoenzyme disassembly and disrupted allostery in patients. Additionally, I will introduce a molecular approach for controlling PKA activity, which is crucial for addressing PKA dysfunction observed across various neurodegenerative diseases.
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Date:24SundayMarch 2024Lecture
Hippocampal pathology and pathophysiology in the development of temporal lobe epileptogenesis
More information Time 11:00 - 12:00Location Gerhard M.J. Schmidt Lecture HallLecturer Prof. Robert S. Sloviter
The Neuroscience Institute MRC 245 Morehouse School of Medicine, Atlanta GAOrganizer Department of Brain SciencesContact Details Show full text description of Host: Prof. Menahem Segal menahem.segal@weizmann.ac.il Fo...» Host: Prof. Menahem Segal menahem.segal@weizmann.ac.il
For accessibility issues: naomi.moses@weizmann.ac.ilAbstract Show full text abstract about In families with febrile seizures and temporal lobe epilepsy...» In families with febrile seizures and temporal lobe epilepsy, mutations affecting different GABAergic mechanisms suggest that failure of chloride conductance to limit depolarization may be directly epileptogenic. This “GABAergic disinhibition” hypothesis has been discounted historically for two reasons. First, early attempts to produce hippocampal sclerosis and epilepsy simply by eliminating hippocampal GABA neurons consistently failed to do so. Second, the notion persists that because clinical epilepsy diagnosis is typically delayed for years or decades after brain injury, temporal lobe epileptogenesis should be presumed to involve a complex pathological transformation process that reaches completion during this “latent period.” Recent advances clarify both issues. Although spatially limited hippocampal GABA neuron ablation causes only submaximal granule cell hyperexcitability, more spatially extensive ablation maximizes granule cell hyperexcitability and triggers nonconvulsive granule cell status epilepticus, hippocampal sclerosis, and epilepsy. Recent studies also show that disinhibited granule cells begin to generate clinically subtle seizures immediately post-injury, and these seizures then gradually increase in duration to become clinically obvious. Therefore, rather than being a seizure-free “gestational” state of potentially interruptible epileptogenesis, the “latent period” is more likely an active epileptic state when barriers to seizure spread and clinical expression are gradually overcome by a kindling process. The likelihood that an epileptic brain state exists long before clinical diagnosis has significant implications for anti-epileptogenesis studies. The location, magnitude, and spatial extent of inherited, autoimmune, and injury-induced disinhibition may determine the latency to clinical diagnosis and establish the continuum between the benign, treatable, and refractory forms of temporal lobe epilepsy.
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Date:25MondayMarch 2024Conference
Mind… The Science
More information Time 08:00 - 08:00Location The David Lopatie Conference CentreChairperson Talia SuissaHomepage Contact -
Date:25MondayMarch 2024Lecture
EPS AI discussion seminar - Neural General Circulation Models for weather and climate predictions
More information Time 15:00Location also via zoom: https://weizmann.zoom.us/j/95890082380?pwd=TnZxc1NoSkxUbjM3SVB0dVpCdVRtZz09
M. Magaritz Seminar RoomLecturer Janni YuvalOrganizer Department of Earth and Planetary SciencesContact -
Date:27WednesdayMarch 2024Lecture
Exploring Inorganic and Organic Biomass for generation of Fuels and Chemical Commodities
More information Time 11:00 - 12:00Location Perlman Chemical Sciences Building
Room 404Lecturer Dr. José Geraldo Nery
São Paulo State University - UNESPOrganizer Department of Molecular Chemistry and Materials ScienceContact Abstract Show full text abstract about Biomass is characterized as "material of biological ori...» Biomass is characterized as "material of biological origin, excluding material embedded in
geological formations or fossilized." It serves as a valuable resource for energy production and as
a foundational material for the synthesis of various commodity and specialty materials. The
composition of biomass is notably more diverse and intricate than that of crude oil, resulting in
significant distinctions between a conventional petroleum refinery and a biomass refinery, often
referred to as a biorefinery. Unlike crude oil, which is typically abundant in gaseous, liquid, and
solid hydrocarbons featuring a high carbon-to-oxygen (C/O) ratio, biomass primarily consists of
complex biomacromolecules with a considerably lower C/O ratio. The conversion of biomass into
commodity chemicals presents a promising approach to diminish society's reliance on fossil fuel
resources—the predominant challenge of the 21st century. This challenge necessitates the
development of tools and technologies to facilitate the transition from a predominantly
petroleum-based to an alternative bio-based chemical industry. The objective of this seminar is
to showcase the recent advancements we have made in enhancing bio-based platform
molecules for the production of commodity or specialty chemicals. We achieve this through the
utilization of C2 to C6 bio-based platforms, exemplified by polyols (e.g., glycerol), furanoids (e.g.,
furfural), and carboxylic acids (e.g., levulinic acid). -
Date:31SundayMarch 2024Lecture
Large scale circulation adjustments to aerosol-cloud interactions and its radiative effect
More information Time 11:00Location Sussman Family Building for Environmental Sciences
M. Magaritz Seminar RoomLecturer Guy Dagan
Hebrew University of JerusalemOrganizer Department of Earth and Planetary SciencesContact Abstract Show full text abstract about The impact of anthropogenic aerosols on clouds is a leading ...» The impact of anthropogenic aerosols on clouds is a leading source of uncertainty in estimating the effect of human activity on the climate system. The challenge lies in the scale difference between clouds (~1-10 km) and general circulation and climate (~1000 km). To address this, we utilize three different novel sets of simulations that allow to resolve convection while also including a epresentation of large-scale processes. Our findings demonstrate that aerosol-cloud interaction intensifies tropical overturning circulation. Employing a weak temperature gradient approximation, we attribute variations in circulation to clear-sky humidity changes driven by warm rain suppression by aerosols. In two sets of simulations accounting for sub-tropical-tropical coupling, we show that aerosol-driven sub-tropical rain suppression leads to increased advection of cold and moist air from the sub-tropics to the tropics, thus enhancing tropical cloudiness. The increased tropical cloudiness has a strong cooling effect by reflecting more of the incoming solar radiation. The classical “aerosol-cloud lifetime effect” is shown here to have a strong remote effect (sub-tropical aerosols increase cloudiness in the tropics), thus widening the concept of cloud adjustments to aerosol perturbation with important implications for marine cloud brightening. -
Date:31SundayMarch 2024Lecture
Science Literacy for All: Implications for Sustainability Education
More information Time 13:00 - 14:00Title IES/SAERI- Sustainability and Energy Research Initiative Seminar SeriesLocation Nella and Leon Benoziyo Building for Biological Sciences
Room 690Lecturer Prof. David Fortus
Department of Science Teaching -WISOrganizer Sustainability and Energy Research Initiative (SAERI)Contact Details Show full text description of Host: Prof. Ron Milo...» Host: Prof. Ron Milo -
Date:31SundayMarch 2024Lecture
Elucidating sites and mechanisms of GLP-1 action
More information Time 15:00 - 16:00Location Arthur and Rochelle Belfer Building for Biomedical Research
Botnar AuditoriumLecturer Prof. Daniel J Drucker
Mt. Sinai Hospital, Lunenfeld Tanenbaum Research Institute University of Toronto, Canada.Organizer Life Sciences
Metabollic Research ForumContact