לוח שנה משולב

For a group G and a normal (=conjugation invariant) subset A, let be the subgroup generated by A, and let X_A be the Cayley graph of with generating set A. 

I will talk about:

1) The diameter of X_A, in the case G is a higher rank lattice. 

2) The mixing time of X_A, in case G is a compact simple Lie group. 

3) Applications of the above. 

Based on joint works and works in progress with Chen Meiri, Itay Glazer, Peter Keevash, Michael Larsen, and Noam Lifshitz.

In this talk we explain how the Toda lattice model, one of the earliest examples of nonlinear completely integrable systems, can demonstrate that certain configurations in the classical phase space are, in fact, symplectic balls in disguise. No background in symplectic geometry is needed. The talk is based on a joint work with Vinicius Ramos and Daniele Sepe.

 

Important information: A light lunch will be served right after. From now on, announcements regarding our Mathematics Colloquium will be sent only to the pure math department mailing list. If you are not on that list and wish to receive future announcements, please REGISTER to this mailing list. There is also a calendar you can add to your own google calendar, it'll be updated whenever a talk is added to the schedule.

We greatly encourage all faculty, students and postdocs to attend. 

See you there!

Shira and Shachar.

Humanity makes great use of the electric field effect: charging and discharging capacitors in low density semiconductors systems is the underpinning of the analog and digital electronics that define our age. At the same time, we know quantum matter to include far more than just electrical conductors and insulators.  I will describe the physics of crystalline graphite multilayers with rhombohedral stacking, where the competition between electron hopping within- and between- the graphene planes leads to a flat dispersion characterized by high electronic density of states and Berry curvature, which can be tuned by a perpendicular electric field.  Using electrostatic gates to tune both this interlayer potential and the total carrier density, I will show that a dizzying variety of magnetic and superconducting states can be realized, often within the same device. The exceptional experimental reproducibility of these structurally simple systems allows us to investigate a variety of effects in a controlled environment, including the role of spin orbit coupling or a moire potential, providing insight into the mechanisms of magnetism and superconductivity.  Most strikingly, quantized Hall effects and superconductivity can be realized in the same field-effect transistor for only slightly different values of a gate voltage, providing a versatile platform both to both study the mechanisms underlying these phases as well as build highly controllable interfaces between these paradigmatic phases of quantum matter.   

Twenty-seven percent of the world’s terrestrial area is classified as arid or hyper-arid, regions that are second only to oceans in the sparsity of measurement sites. Contrary to popular perception, these desert areas are dynamic ecosystems that respond sensitively to changes in water availability, temperature, and carbon dioxide (CO2) levels. As such, they can serve as important indicators and potentially moderators of climate change. Efforts to understand the dynamics and feedback mechanisms between the main players affecting desert weather and climate can be divided, by-and-large, into two groups: (1) addressing the most pressing knowledge gaps of desert weather and climate systems; and (2) exploring processes that have not previously been considered but are hypothesized to be more important than presumed, representing a realm of "unknown unknowns". One example to the “unknown unknowns” realm is related to non-rainfall water inputs (i.e., fog, dew, and atmospheric water vapor adsorption). Traveling between the Negev, Namib, and Sahara deserts, we will look into this largely overlooked phenomenon. We will point to the similarities between these deserts and ask how widespread this phenomenon may be. Spoiler - we don't know, but we sure need to.

How cancer arises from a single normal cell is still the subject of active debate, affecting intervention strategies. While many cells may harbor oncogenic mutations, only a few unpredictably end-up developing a full-blown tumour. Various theories have been proposed to explain that transition, but none has been tested in vivo at the single cell level. Here using an optogenetic approach we permanently turn on an oncogene (KRASG12V) in a single cell of a zebrafish brain that, only in synergy with the transient co-activation of a reprogramming factor (VENTX/NANOG/OCT4), undergoes a deterministic malignant transition and robustly and reproducibly develops within 6 days into a full-blown cancer. The controlled way in which a single cell can thus be manipulated to give rise to cancer lends support to the “ground state theory of cancer initiation” through “short-range dispersal” of the first malignant cells preceding tumour growth.P. Scerbo B. Tisserand, M. Delagrange , H.Debare,   B.Ducos, D. BensimonStudents interested in meeting the speaker after the seminar may sign up here:LINKFOR THE LATEST UPDATES AND CONTENT ON SOFT MATTER AND BIOLOGICAL PHYSICS AT THE WEIZMANN, VISIT OUR WEBSITE: https://www.bio

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