Pages

Event search results

  • Date:18MondayMarch 2024

    Atom-Probe Tomography and its Myriad Applications in Chemistry

    More information
    Time
    11:00 - 12:15
    Location
    Gerhard M.J. Schmidt Lecture Hall
    Lecturer
    Prof. David N. Seidman
    McCormick School of Engineering, Northwestern University
    Organizer
    Department of Molecular Chemistry and Materials Science
    Homepage
    Contact
    AbstractShow 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.
    Colloquia
  • Date:18MondayMarch 2024

    Foundations of Computer Science Seminar

    More information
    Time
    11:15 - 12:15
    Title
    Toward Better Depth Lower Bounds: A KRW-like theorem for Strong Composition
    Location
    Jacob Ziskind Building
    Room 155
    Lecturer
    Or Meir
    University of Haifa
    Organizer
    Department of Computer Science and Applied Mathematics
    Seminar
    Contact
    AbstractShow 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
    Lecture
  • Date:19TuesdayMarch 2024

    STATISTICAL MECHANICS DAY XV

    More information
    Time
    08:00 - 08:00
    Location
    Nella and Leon Benoziyo Physics Library
    Library Room
    Chairperson
    Oren Raz
    Organizer
    Department of Physics of Complex Systems
    Homepage
    Contact
    Conference
  • Date:19TuesdayMarch 2024

    Israeli RNA Meeting 2023 in memory of Prof. Yossi Sperling

    More information
    Time
    08:30 - 16:00
    Location
    The David Lopatie Conference Centre
    Chairperson
    Schraga Schwartz
    Organizer
    Abisch-Frenkel RNA Therapeutics Center , Azrieli Institute for Systems Biology
    Contact
    Conference
  • Date:19TuesdayMarch 2024

    iSCAR Breakfast Seminar

    More information
    Time
    09:00 - 10:00
    Location
    Max and Lillian Candiotty Building
    Auditorium
    Lecturer
    Dr. Yaniv Elkouby
    From the stem cell to the follicle: Unpredicted cellular machineries in oocyte production and reproduction
    Organizer
    Department of Immunology and Regenerative Biology
    Contact
    Lecture
  • Date:19TuesdayMarch 2024

    Dimensionality bottleneck uncovers simple action selection rules in hunting zebrafish

    More information
    Time
    12:30 - 13:30
    Location
    Gerhard M.J. Schmidt Lecture Hall
    Lecturer
    Dr. Lilach Avitan
    Edmond and Lily Safra Center for Brain Sciences The Hebrew University of Jerusalem
    Organizer
    Department of Brain Sciences
    Contact
    DetailsShow 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.il
    AbstractShow 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.
    Lecture
  • Date:19TuesdayMarch 2024

    New approaches to glycan synthesis and glycan-based biosensing

    More information
    Time
    14:00 - 15:00
    Location
    Gerhard M.J. Schmidt Lecture Hall
    Lecturer
    Prof. Mattan Hurevich
    Institute of Chemistry Hebrew University
    Organizer
    Department of Chemical and Structural Biology
    Contact
    Lecture
  • Date:20WednesdayMarch 2024

    Employing the Hegelian Aufhebung Principle for Predicting New Catalytic Pathways

    More information
    Time
    11:00 - 12:00
    Location
    Perlman Chemical Sciences Building
    Room 404
    Lecturer
    Prof. Anatoly Frenkel
    Stony Brook University and Brookhaven National Laboratory
    Organizer
    Department of Molecular Chemistry and Materials Science
    Contact
    AbstractShow 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.
    Lecture
  • Date:21ThursdayMarch 2024

    Special Guest Seminar with Prof. Eugene V. Koonin

    More information
    Time
    11:00 - 12:00
    Title
    "Global structure and evolution of the virosphere"
    Location
    Arthur and Rochelle Belfer Building for Biomedical Research
    Botnar Auditorium
    Lecturer
    Prof. Eugene V. Koonin
    Organizer
    Department of Molecular Genetics
    Contact
    AbstractShow 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.
    Lecture
  • Date:21ThursdayMarch 2024

    Physics Colloquium

    More information
    Time
    11:15 - 12:30
    Title
    Fractional statistics of anyons in mesoscopic colliders
    Location
    Edna and K.B. Weissman Building of Physical Sciences
    Auditorium
    Lecturer
    Prof. Gwendal Fève
    Sorbonne University , Paris, France
    Organizer
    Department of Condensed Matter Physics
    Contact
    DetailsShow full text description of Refreshments will be served at 11:00...»
    Refreshments will be served at 11:00
    AbstractShow 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).

    Colloquia
  • Date:21ThursdayMarch 2024

    The Golden Approach for Overcoming Bio-Barriers: Delivering Nanomedicine to Brain and Beyond

    More information
    Time
    14:00 - 15:00
    Location
    Max and Lillian Candiotty Building
    Auditorium
    Lecturer
    Prof. Rachela Popovtzer
    Faculty of Engineering and The Institute of Nanotechnology and Advanced Materials. Bar-Ilan University, Israel
    Organizer
    Dwek Institute for Cancer Therapy Research
    Cancer Research Club
    Contact
    DetailsShow full text description of Meeting URL: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6K...»
    Meeting URL: https://weizmann.zoom.us/j/5065402023?pwd=a3Z6KzRCU0xJaUFoM2Y5emZwZm1oZz09

    Lecture
  • Date:21ThursdayMarch 2024

    Chemistry and the Information beyond the Genome Sequence

    More information
    Time
    14:00 - 15:00
    Location
    Gerhard M.J. Schmidt Lecture Hall
    Lecturer
    Prof. Andreas Marx
    Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz Germany
    Organizer
    Department of Chemical and Structural Biology
    Contact
    Lecture
  • Date:21ThursdayMarch 2024

    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 - 16:00
    Location
    Nella and Leon Benoziyo Building for Biological Sciences
    Auditorium
    Lecturer
    Dr. Ronit Ilouz
    Molecular and Cellular Mechanisms of Neurological Diseases, Bar-Ilan University
    Organizer
    Department of Biomolecular Sciences
    Contact
    DetailsShow 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.
    Lecture
  • Date:24SundayMarch 2024

    Hippocampal pathology and pathophysiology in the development of temporal lobe epileptogenesis

    More information
    Time
    11:00 - 12:00
    Location
    Gerhard M.J. Schmidt Lecture Hall
    Lecturer
    Prof. Robert S. Sloviter
    The Neuroscience Institute MRC 245 Morehouse School of Medicine, Atlanta GA
    Organizer
    Department of Brain Sciences
    Contact
    DetailsShow 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.il
    AbstractShow 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.
    Lecture
  • Date:25MondayMarch 2024

    Mind… The Science

    More information
    Time
    08:00 - 08:00
    Location
    The David Lopatie Conference Centre
    Chairperson
    Talia Suissa
    Homepage
    Contact
    Conference
  • Date:25MondayMarch 2024

    EPS AI discussion seminar - Neural General Circulation Models for weather and climate predictions

    More information
    Time
    15:00
    Location
    also via zoom: https://weizmann.zoom.us/j/95890082380?pwd=TnZxc1NoSkxUbjM3SVB0dVpCdVRtZz09
    M. Magaritz Seminar Room
    Lecturer
    Janni Yuval
    Organizer
    Department of Earth and Planetary Sciences
    Contact
    Lecture
  • Date:27WednesdayMarch 2024

    Exploring Inorganic and Organic Biomass for generation of Fuels and Chemical Commodities

    More information
    Time
    11:00 - 12:00
    Location
    Perlman Chemical Sciences Building
    Room 404
    Lecturer
    Dr. José Geraldo Nery
    São Paulo State University - UNESP
    Organizer
    Department of Molecular Chemistry and Materials Science
    Contact
    AbstractShow 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).
    Lecture
  • Date:31SundayMarch 2024

    Large scale circulation adjustments to aerosol-cloud interactions and its radiative effect

    More information
    Time
    11:00
    Location
    Sussman Family Building for Environmental Sciences
    M. Magaritz Seminar Room
    Lecturer
    Guy Dagan
    Hebrew University of Jerusalem
    Organizer
    Department of Earth and Planetary Sciences
    Contact
    AbstractShow 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.
    Lecture
  • Date:31SundayMarch 2024

    Science Literacy for All: Implications for Sustainability Education

    More information
    Time
    13:00 - 14:00
    Title
    IES/SAERI- Sustainability and Energy Research Initiative Seminar Series
    Location
    Nella and Leon Benoziyo Building for Biological Sciences
    Room 690
    Lecturer
    Prof. David Fortus
    Department of Science Teaching -WIS
    Organizer
    Sustainability and Energy Research Initiative (SAERI)
    Contact
    DetailsShow full text description of Host: Prof. Ron Milo...»
    Host: Prof. Ron Milo
    Lecture
  • Date:02TuesdayApril 2024

    iSCAR Seminar

    More information
    Time
    09:00 - 10:00
    Location
    Max and Lillian Candiotty Building
    Auditorium
    Organizer
    Department of Immunology and Regenerative Biology
    Contact
    Lecture

Pages