תוצאות חיפוש לאירועים
Studying the role of fluids in the mantle through natural samples and experiments
More information שעה11:00 - 12:00 מיקוםבניין משפחת זוסמן
M. Magaritz Seminar Room
Institute of Earth Sciences, The Hebrew University of Jerusalem
מארגןהמחלקה למדעי כדור הארץ וכוכבי הלכת צרו קשר תקציר Show full text abstract about Mantle fluids are the primary carriers of key volatile eleme...»Mantle fluids are the primary carriers of key volatile elements that make the Earth’s long-term planetary habitability possible. The interaction of such volatile-rich fluids with the mantle rocks, especially the sub-cratonic lithospheric mantle leads to alteration of the mantle as well as its melting. High-density fluids encased inside diamonds are the best natural representation of mantle fluid compositions, suggesting their compositions are saline, silicic or carbonatitic. However, the origin and role in the mantle as well as their role in altering the mantle are still unclear.
In my research, we approach these questions by experimentally simulating the interaction of volatile-rich fluids with mantle rocks at known pressure and temperature relevant to the mantle. Examining different mixtures of volatiles (H2O and CO2) and mantle rocks (peridotite and eclogite), we attempt to understand the origin of each type of fluid found in diamonds as well as study the effect of such interaction on the mantle chemistry and mineralogy.
Compiling many experimental studies reveals that fluids ranging from silicic to low-Mg carbonatitic are formed in systems of eclogite+H2O+CO2, the more CO2 in the system, the more carbonatitic the fluid is. Fluids ranging from low-Mg carbonatitic to high-Mg carbonatitic in nature are the results of the formation of fluids in the peridotite-H2O-CO2 system. The more CO2 in the system, the more high-Mg carbonatitic the fluid composition is. These results suggest that the various fluids found in the mantle result from changes in the bulk composition of the mantle rocks.
The mantle rocks are significantly affected during percolation of such fluids through them. For example, experimentally interacting silicic fluid with peridotite demonstrated the formation of various metasomatic peridotites as a function of pressure and temperature, composing of amphibole and mica. The mineral assemblages, chemistry, and P-T conditions in the experiments are similar to those found in metasomatic xenoliths from Kimberly, South Africa, and surrounding localities.
Magnetic Resonance Seminar: "Quantum sensing of out-of-equilibrium systems with magnetic resonance”
More information שעה16:00 - 17:00 מיקוםבניין פרלמן למדעי הכימיה
Shlomo Alexander Science Lounge
מרצהDr. Gonzalo A. Alvarez
Centro Atómico Bariloche, Instituto Balseiro & Instituto de Nanociencia y Nanotecnologia
מארגןמרכז למדע וטכנולוגיה קוונטית צרו קשר תקציר Show full text abstract about Reliable processing of quantum information is crucial for qu...»Reliable processing of quantum information is crucial for quantum technologies development. Characterizing the ubiquitous out-of-equilibrium quantum systems [1-3] is essential for designing optimal control and quantum sensing strategies. However, this task is highly challenging due to the complex high-order correlations and non-stationary nature. In this talk, I will present methods to characterize the decoherence of out-of-equilibrium quantum systems [1,4-6]. Using quantum simulations with Solid-State Nuclear Magnetic Resonance, we quantify "out-of-time order correlations" (OTOCs [2-3]) to define a critical threshold in disturbances to achieve reliable control of large quantum systems [1,4-5]. Furthermore, we develop a framework for quantum sensing the dynamics of out-of-equilibrium systems . The sensor manifests spectral and non-Markovian properties, providing a quantum technology to probe time-correlation properties and mitigate the decoherence effects of non-stationary environments.
 G. A. Alvarez, D. Suter, R. Kaiser. Science 349, 846 (2015).
 R.J. Lewis-Swan, A. Safavi-Naini, A.M. Kaufman, A.M. Rey. Nat. Rev. Phys. 1, 627 (2019).
 B. Swingle. Nat. Phys. 14, 988 (2018).
 F.D. Dominguez, M.C. Rodriguez, R. Kaiser, D. Suter, G.A. Alvarez. Phys. Rev. A 104, 012402 (2021).
 F.D. Dominguez, G.A. Alvarez. Phys. Rev. A 104, 062406 (2021).
 M. Kuffer, A. Zwick, G.A. Alvarez. PRX Quantum 3, 020321 (2022).
Date:29שנימאי 202331רביעימאי 2023כנסים
Ultrafast, Nonlinear and Quantum Optics
More information שעה08:00 - 08:00 מיקוםמרכז כנסים על-שם דויד לופאטי יושב ראשTalia Tzahor מארגןהמחלקה לפיסיקה של מערכות מורכבות , מרכז לפוטוניקה על-שם קראון דף בית צרו קשר
Systems Biology Seminar 2022-2023
More information שעה10:00 - 11:00 מיקוםבניין ארתור ורושל בלפר למחקר ביורפואי
מארגןמכון עזריאלי למערכות ביולוגיות צרו קשר
Solar Panels for Light-to-Chemical Conversion
More information שעה11:00 - 12:15 כותרת2023 G.M.J. SCHMIDT MEMORIAL LECTURE מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהSarah Amzallag מארגןהפקולטה לכימיה דף בית צרו קשר תקציר Show full text abstract about Solar panels are well known to produce electricity, but they...»Solar panels are well known to produce electricity, but they are also in early-stage development for the production of sustainable fuels and chemicals. These panels mimic plant leaves in shape and function as demonstrated for overall solar water splitting to produce green H2 by the laboratories of Nocera and Domen.1,2
This presentation will give an overview of our recent progress to construct prototype solar panel devices for the conversion of carbon dioxide and solid waste streams into fuels and higher-value chemicals through molecular surface-engineering of solar panels with suitable catalysts. Specifically, a standalone ‘photoelectrochemical leaf’ based on an integrated lead halide perovskite-BiVO4 tandem light absorber architecture has been built for the solar CO2 reduction to produce syngas.3 Syngas is an energy-rich gas mixture containing CO and H2 and currently produced from fossil fuels. The renewable production of syngas may allow for the synthesis of renewable liquid oxygenates and hydrocarbon fuels. Recent advances in the manufacturing have enabled the reduction of material requirements to fabricate such devices and make the leaves sufficiently light weight to even float on water, thereby enabling application on open water sources.4 The tandem design also allows for the integration of biocatalysts and the selective and bias-free conversion of CO2-to-formate has been demonstrated using enzymes.5 The versatility of the integrated leaf architecture has been demonstrated by replacing the perovskite light absorber by BiOI for solar water and CO2 splitting to demonstrate week-long stability.6
An alternative solar carbon capture and utilisation technology is based on co-deposited semiconductor powders on a conducting substrate.2 Modification of these immobilized powders with a molecular catalyst provides us with a photocatalyst sheet that can cleanly produce formic acid from aqueous CO2.7 CO2-fixing bacteria grown on such a ‘photocatalyst sheet’ enable the production of multicarbon products through clean CO2-to-acetate conversion.8 The deposition of a single semiconductor material on glass gives panels for the sunlight-powered conversion plastic and biomass waste into H2 and organic products, thereby allowing for simultaneous waste remediation and fuel production.9 The concept and prospect behind these integrated systems for solar energy conversion,10 related approaches,11 and their relevance to secure and harness sustainable energy supplies in a fossil-fuel free economy will be discussed.
Foundations of Computer Science Seminar
More information שעה11:15 - 12:30 כותרתThe Randomized k-Server Conjecture is False! מיקוםבניין יעקב זיסקינד
Hebrew University of Jerusalem
מארגןהמחלקה למדעי המחשב ומתמטיקה שימושית
צרו קשר פרטים נוספים Show full text description of We prove a few new lower bounds on the randomized competitiv...»We prove a few new lower bounds on the randomized competitive ratio for the k-server problem and other related problems, resolving some long-standing conjectures. In particular, for metrical task systems (MTS) we asympotically settle the competitive ratio and obtain the first improvement to an existential lower bound since the introduction of the model 35 years ago (in 1987).
More concretely, we show:
1. There exist (k 1)-point metric spaces in which the randomized competitive ratio for the k-server problem is Omega(log^2 k). This refutes the folklore conjecture (which is known to hold in some families of metrics) that in all metric spaces with at least k 1 points, the competitive ratio is Theta(logk).
2. Consequently, there exist n-point metric spaces in which the randomized competitive ratio for MTS is Omega(log^2 n). This matches the upper bound that holds for all metrics. The previously best existential lower bound was Omega(logn) (which was known to be tight for some families of metrics).
3. For all k
תקציר Show full text abstract about We prove a few new lower bounds on the randomized competitiv...»We prove a few new lower bounds on the randomized competitive ratio for the k-server problem and other related problems, resolving some long-standing conjectures. In particular, for metrical task systems (MTS) we asympotically settle the competitive ratio and obtain the first improvement to an existential lower bound since the introduction of the model 35 years ago (in 1987).
More concretely, we show:
1. There exist (k 1)-point metric spaces in which the randomized competitive ratio for the k-server problem is Ω(log^2 k). This refutes the folklore conjecture (which is known to hold in some families of metrics) that in all metric spaces with at least k 1 points, the competitive ratio is Θ(logk).
2. Consequently, there exist n-point metric spaces in which the randomized competitive ratio for MTS is Ω(log^2 n). This matches the upper bound that holds for all metrics. The previously best existential lower bound was Ω(logn) (which was known to be tight for some families of metrics).
3. For all k<n∈ℕ, for *all* n-point metric spaces the randomized k-server competitive ratio is at least Ω(logk), and consequently the randomized MTS competitive ratio is at least Ω(logn). These universal lower bounds are asymptotically tight. The previous bounds were Ω(logk/loglogk) and Ω(logn/loglogn), respectively.
4. The randomized competitive ratio for the w-set metrical service systems problem, and its equivalent width-w layered graph traversal problem, is Ω(w^2). This slightly improves the previous lower bound and matches the recently discovered upper bound.
5. Our results imply improved lower bounds for other problems like k-taxi, distributed paging and metric allocation.
These lower bounds share a common thread, and other than the third bound, also a common construction.
Joint work with Sébastien Bubeck and Christian Coester.
Site-Specific Isopeptide Bond Formation: A Powerful Tool for the Generation of Potent and Nontoxic Antimicrobial Peptides
More information שעה10:00 - 11:00 מיקוםבניין לביוכימיה על שם נלה וליאון בנוזיו
מרצהDr. Naiem Wani
Dept. of Biomolecular Sciences-WIS
מארגןהמחלקה למדעים ביומולקולריים צרו קשר
Homogeneous (De)hydrogenative Catalysis for a Circular Economy
More information שעה11:00 - 12:00 מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהDr. Amit Kumar
School of Chemistry, University of St. Andrews, St. Andrews, KY169ST, UK
מארגןהמחלקה לכימיה מולקולרית ולמדע חומרים צרו קשר תקציר Show full text abstract about The development of sustainable methods for the closed-loop p...»The development of sustainable methods for the closed-loop production and recycling of plastics is an important challenge of current times. Reactions based on catalytic (de)hydrogenation are atom-economic, and sustainable routes for organic transformations.1 Using the following examples, this lecture will discuss the application of homogeneous (de)hydrogenative catalysis for the synthesis and degradation of polymers to enable a circular economy: (a) synthesis of polyamides/nylons from the ruthenium catalysed dehydrogenative coupling of diamines and diols and its reverse reaction i.e. hydrogenative depolymerisation of nylons,2 (b) synthesis of polyureas from the ruthenium/manganese catalysed dehydrogenative coupling of diamines3,4 and methanol, and its reverse reaction, i.e. hydrogenative depolymerisation of polyureas (Figure 1B)5, (c) Synthesis of polyethyleneimines from manganese catalysed coupling of ethylene glycol and ethylenediamine or the self-coupling of ethanolamine,6 and (d) Synthesis of polyureas and polyurethanes from the dehydrogenative coupling of diformamides and diamines/diols and its reverse reaction i.e. hydrogenative depolymerisation of polyureas and polyurethanes to diformamides and diamines/diols.7 Some applications of some of the polymers made using dehydrogenative processes in the field of batteries will also be discussed.8
Bacterial community indicators to monitor the health of our changing environment
More information שעה11:30 - 12:30 מיקוםhttps://weizmann.zoom.us/j/92703563162?pwd=cW5pb0Nzcm1XS2RObyt6NVZHRUFHUT09 מרצהProf. Gavin Lear
University of Auckland
מארגןהמחלקה למדעי הצמח והסביבה צרו קשר
Cognitive neuroscience of learning and memory in human infants
More information שעה12:30 - 13:30 מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהProf. Nick Turk-Browne
Dept of Psychology, Yale University
מארגןהמחלקה למדעי המוח צרו קשר פרטים נוספים Show full text description of Host- Dr. Michal Ramot firstname.lastname@example.org For ac...»Host- Dr. Michal Ramot email@example.com
For accessibility issues: firstname.lastname@example.org
תקציר Show full text abstract about In this talk, I will present the approach my lab has develop...»In this talk, I will present the approach my lab has developed for performing fMRI studies in awake infants during cognitive tasks. I will share some of our recent studies and highlight some of the big open questions that remain to be addressed, with potential to reveal the brain systems underlying how infants perceive and attend to their environment, why infants are such proficient learners, and why we all have amnesia for infant experiences. Despite countless limitations and challenges at present, this work suggests that awake infant fMRI could become more feasible, useful, and ubiquitous in cognitive neuroscience.
Electrosome assembly: a first look at the structural principles underlying ion channel biogenesis
More information שעה14:00 - 15:00 מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהProf. Daniel Minor
Departments of Biochemistry & Biophysics University of California San Francisco
מארגןהמחלקה לביולוגיה מבנית וכימית צרו קשר
Evolution in a Cup – use of small-scale bioreactors to study dynamics of microorganism
More information שעה09:00 - 10:00 מיקוםבניין ע"ש מקס ולילאן קנדיוטי
מרצהDr. Ghil Jona
The Bacteriology & Genomic Repository Unit
מארגןהמחלקה לתשתיות מחקר מדעי החיים צרו קשר
More information שעה11:15 - 12:30 כותרתElastic Strain Engineering for Unprecedented Properties מיקוםבניין הפיסיקה ע"ש עדנה וק.ב. וייסמן
מרצהProf. Ju Li
MIT – Cambridge, Massachusetts, USA
מארגןהפקולטה לפיסיקה צרו קשר פרטים נוספים Show full text description of Refreshments at 11:00...»Refreshments at 11:00 תקציר Show full text abstract about The emergence of “ultra-strength materials” that can withsta...»The emergence of “ultra-strength materials” that can withstand significant fractions of the ideal strength at component scale without any inelastic relaxation harbingers a new field within mechanics of materials. Recently, we have experimentally achieved more than 13% reversible tensile strains in Si that fundamentally redefines what it means to be Si, and ~7% uniform tensile strain in micron-scale single-crystalline diamond bridge arrays, where thousands of transistors and quantum sensors can be integrated in one diamond microbridge. Elastic Strain Engineering (ESE) aims to endow material structures with very large stresses and stress gradients to guide electronic, photonic, and spin excitations and control energy, mass, and information flows. As “smaller is stronger” for most engineering materials at room temperature, a much larger dynamical range of tensile-and-shear deviatoric stresses for small-scale structures can be achieved, as the defect (e.g., dislocation, crack) population dynamics change from defect-propagation to defect-nucleation controlled. Thus, all six stress components can be used to tune the physical and chemical properties of a material like a 7-element alloy. Four pillars of ESE need to be addressed experimentally and computationally: (a) making materials and structures that can withstand deviatoric elastic strain patterns that are exceptionally large and extended in space-time volume, inhomogeneous, dynamically reversible, or combinations thereof, (b) measuring and understanding how functional properties such as photonic and electronic characteristics vary with imposed elastic strain tensor, (c) characterizing and modeling the mechanisms of stress relaxations; the goal is not to use them for forming but to defeat them at service temperatures (usually room temperature and above) and extended timescales, and (d) computational design based on first principles, e.g. predicting ideal strength surface, topological changes in band structures, etc. assisted by machine learning.
Vision and AI
More information שעה12:15 - 13:15 כותרתSpaceborne multi-view computational tomography (CT) מיקוםבניין יעקב זיסקינד
מארגןהמחלקה למדעי המחשב ומתמטיקה שימושית
צרו קשר תקציר Show full text abstract about We describe new computer vision tasks stemming from upcoming...»We describe new computer vision tasks stemming from upcoming multiview tomography from space. Solutions involve both novel imaging hardware and computational algorithms, based on machine learning and differential rendering. This can transform climate research and medical X-ray CT. The key idea is that advanced computing can enable computed tomography of volumetric scenes, based scattered radiation. We describe an upcoming space mission (CloudCT, funded by the ERC). It has 10 nano-satellites that will fly in an unprecedented formation, to capture the same scene (cloud fields) from multiple views simultaneously, using special cameras. The satellites and cameras are built now. They - and the algorithms - are specified to meet computer vision tasks, including geometric and polarimetric self-calibration in orbit, and estimation of 3D volumetric distribution of matter and microphysical properties. Deep learning and differential rendering enable analysis to scale to big data downlinked from orbit. Core ideas are generalized for medical X-ray imaging, to enable significant reduction of dose and acquisition time, while extracting chemical properties per voxel. The creativity of the computer vision and graphics communities can assist in critical needs for society, and this talk points out relevant challenges.
Volatile cortical working memory representations crystalize with practice
More information שעה12:30 - 13:30 מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהProf. Peyman Golshani
David Geffen School of Medicine, UCLA
מארגןהמחלקה למדעי המוח צרו קשר פרטים נוספים Show full text description of Host-Prof. Ofer Yizhar email@example.com For acc...»Host-Prof. Ofer Yizhar firstname.lastname@example.org
For accessibility issues: email@example.com
תקציר Show full text abstract about Working memory (WM), the process through which information i...»Working memory (WM), the process through which information is transiently maintained and manipulated over a brief period of time, is essential for most cognitive functions. However, the mechanisms underlying the generation and stability of WM neuronal representations at the population level remain elusive. To uncover these mechanisms, we trained head-fixed mice to perform an olfactory working memory task and used optogenetics to delineate circuits causal for behavioral performance. We used mesoscopic and light bead two photon imaging to record from up to 35,000 secondary motor cortical neurons simulataneously across multiple days and show differential stabilization of different task parameters with learning and practice of the task. We find that cortical working memory representations causal for task performance are highly volatile but only stabilize after multiple days of practice well after task learning. We hypothesize that representational drift soon after learning may allow for higher levels of flexibility for new task rules.
I will also review some of the new open-source tools developed for large-scale imaging of neural activity patterns in freely behaving animals.
Somatic mutation in normal tissues
More information שעה14:00 - 15:00 מרצהDr. Inigo Martincorena
Group Leader, Sanger Institute, Cambridge, UK.
מארגןהמכון לחקר הטיפול בסרטן עש דואק
Cancer Research Club
צרו קשר פרטים נוספים 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
Ben May Lecutre Series
More information שעה14:00 - 15:00 כותרתCoherence Maps and State-to-State Pathways of Excitation Energy Transfer מיקוםאולם הרצאות ע"ש גרהרד שמידט מרצהProf Nancy Makri
University of Illinois at Urbana-Champaign
מארגןמרכז לתיאוריה כימית וחישוביות על שם בן מיי צרו קשר תקציר Show full text abstract about The interplay among electronic coherence, vibrational dampin...»The interplay among electronic coherence, vibrational damping, quantum dispersion, topological effects and thermal fluctuations leads to rich behaviors in the dynamics of excitation energy flow. We use real-time path integral methods developed in our group to perform fully quantum mechanical simulations of excitation energy transfer in large molecular aggregates. The systems are described through a Frenkel exciton Hamiltonian where all vibrational normal modes of each molecular unit and their coupling to the ground and excited electronic states are treated explicitly at any temperature. Simulations have been carried out in J aggregates of perylene bisimide, model dendrimers, and photosynthetic light harvesting complexes. Coherence maps offer powerful visualization tools that reveal the creation and destruction of quantum superpositions and enable a state-to-state pathway analysis of energy flow.
Special guest seminar
More information שעהכל היום כותרתT cell memory, metabolism and the microbiome מיקוםבניין ע"ש מקס ולילאן קנדיוטי
מרצהProfessor Sammy Bedoui מארגןהמחלקה לאימונולוגיה ורגנרציה ביולוגית צרו קשר
More information שעה11:00 - 12:00 מיקוםבניין משפחת זוסמן
M. Magaritz Seminar Room
מארגןהמחלקה למדעי כדור הארץ וכוכבי הלכת צרו קשר
Chemical and Biological Physics Guest Seminar
More information שעה10:00 - 11:00 כותרתMaterials with a twist: atomically controlled interfaces for clean energy מיקוםבניין פרלמן למדעי הכימיה
מרצהProf Magali Lingenfelder
Max Planck-EPFL Laboratory for Molecular Nanoscience and Technology, Ecole Polytechnique Federale de Lausanne (EPFL)
מארגןהמחלקה לפיסיקה כימית וביולוגית צרו קשר תקציר Show full text abstract about Our society faces a critical challenge in shifting from a re...»Our society faces a critical challenge in shifting from a reliance on carbon-based energy to sustainable renewable sources. A key step towards achieving clean energy lies in developing efficient catalysts that can convert chemical energy into electricity or use electrons to generate chemical energy.
In our research group, we tackle these challenges by creating customized materials that draw inspiration from nature (biomimicry) and combine principles from interfacial chemistry and surface physics. For this presentation, I focus on the process of photosynthesis as inspiration for the design, characterization, and dynamic nature of functional interfaces that drive energy conversion processes such as CO2 electroreduction and water splitting.
I will also discuss the application of cutting-edge scanning probe microscopy, which allows us to visualize dynamic electrochemical processes at the nanoscale (operando imaging). Additionally, I will highlight our use of unconventional strategies that leverage chiral molecules and abundant two-dimensional materials to enhance electrocatalytic conversion processes.
(References : Nanoletters, 2021, 21, 2059; Nature Comm., 2022, 13, 3356, IJC 62, 11, 2022).