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BEGIN:VEVENT
DTSTAMP:20240806T022347Z
UID:1715068800@ist.ac.at
DTSTART:20240507T100000
DTEND:20240507T110000
DESCRIPTION:Speaker: Noga Alon\nhosted by Matthew Kwan\nAbstract: I will de
scribe a recent joint work with Matia Bucic and Lisa Sauermannabout the in
vestigation of extremal problems in discrete geometryfor typical norms.The
results include surprisingly tight solutions of the unit and distinctdist
ances problems for typical norms\, as well as a determination of thechroma
tic number of the unit distance graph for a typical planar norm.This settl
es\, in a strong form\, questions and conjectures of Matousek\,of Brass\,
of Chilakamarri and Robertson and of Brass\, Moser and Pach.
LOCATION:Mondi 2\, Central Building\, ISTA
ORGANIZER:omerhalil.unal@ist.ac.at
SUMMARY:Noga Alon: Distance problems for typical norms
URL:https://talks-calendar.ista.ac.at/events/4944
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20240806T022347Z
UID:1715155200@ist.ac.at
DTSTART:20240508T100000
DTEND:20240508T110000
DESCRIPTION:Speaker: Roy Meshulam\nhosted by Matthew Kwan\nAbstract: In rec
ent years there is a growing interest in higher dimensional random complex
es\, both as natural extensions of random graphs\, and as potential tools
for new applications. We will focus on relatively new models of random com
plexes and their generic topological properties:1. A classical theorem of
Alon and Roichman asserts that the Cayley graph C(G\,S) of a group G with
respect to a logarithmic size random subset S of G is a good expander. We
consider a k-dimensional analogue of Cayley graphs\, called Balanced Cayle
y Complexes\, discuss the spectral gap of their (k-1)-Laplacian and in par
ticular obtain a high dimensional version of the Alon-Roichman theorem.2.
A permutation complex is the order complex of the intersection of two line
ar orders. We describe some properties of these complexes and discuss boun
ds on the probability that a permutation complex associated with random or
ders is topologically k-connected.Joint work with Omer Moyal.3. A classica
l result of Erdos and Gallai asserts that a graph G=(V\,E) with |E|> k(|V|
-1)/2 must contain a simple cycle of length at least k+1. We describe a hi
gh dimensional qualitative version of this result and discuss some questio
ns that arise in the random setting.Joint work with Ilan Newman and Yuri R
abinovich.
LOCATION:Moonstone Seminar Room C\, ISTA
ORGANIZER:omerhalil.unal@ist.ac.at
SUMMARY:Roy Meshulam: Aspects of Random Simplicial Complexes
URL:https://talks-calendar.ista.ac.at/events/4950
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20240806T022347Z
UID:1715158800@ist.ac.at
DTSTART:20240508T110000
DTEND:20240508T120000
DESCRIPTION:Speaker: Petar N. Petrov\nhosted by Mikhail Lemeshko\nAbstract:
Cryo-electron microscopy can visualize biomolecules at high resolution in
a near-native state\, but the technique is limited by the low contrast of
specimens together with their sensitivity to electron radiation. To maxim
ize image contrast\, a phase plate can be employed to apply an additional
delay between the scattered and unscattered beams in a diffraction plane o
f the microscope. While this approach is widely used in optical microscopy
\, phase plates developed for electron microscopy have been prone to being
charged by or scattering the electron beam\, leading to unstable behavior
and resolution loss. To overcome these limitations\, we have developed a
laser-based phase plate (LPP). A laser beam\, amplified and focused by a F
abry-Perot optical cavity\, intersects the unscattered electron beam to im
part the desired phase shift. The LPP provides a stable phase shift over h
ours while keeping material objects far from the electron beam path to avo
id scattering and decoherence. The reliability of the LPP paves the way fo
r several future directions in cryo-electron microscopy and tomography. Im
proved contrast at low spatial frequencies enables detection of small part
icles inaccessible to conventional (defocus-based) phase contrast imaging\
, as well as superior correction of beam-induced motions. Additionally\, t
he LPP eliminates the need for specimen defocus and\, in combination with
a spherical aberration corrector\, permits near-perfect contrast transfer
over many orders of magnitude in resolution (from ~100 nm to 0.1 nm). Simu
ltaneous visualization of both small and large structural features promise
s to benefit cryo-electron tomography by providing high-resolution informa
tion together with larger-scale context. I will show our progress on singl
e-particle reconstructions and tomography with the LPP and discuss prospec
ts for the new imaging modalities enabled by the LPP based on a combinatio
n of experiments and simulations.
LOCATION:Moonstone Building\, Seminar Room C\, ISTA
ORGANIZER:omerhalil.unal@ist.ac.at
SUMMARY:Petar N. Petrov: Cryo-electron microscopy with a laser phase plate
URL:https://talks-calendar.ista.ac.at/events/4961
END:VEVENT
BEGIN:VEVENT
DTSTAMP:20240806T022347Z
UID:1720771200@ist.ac.at
DTSTART:20240712T100000
DTEND:20240712T110000
DESCRIPTION:Speaker: Stefan Wuttke\nhosted by Maria Ibanez\nAbstract: The c
hemistry of metal-organic and covalent organic frameworks (MOFs and COFs)
is perhaps the most diverse and inclusive among the chemical sciences\, an
d yet it can be radically expanded by blending it with nanotechnology. The
result is reticular nanoscience\, an area of reticular chemistry that has
an immense potential in virtually any technological field.In this talk\,
we explore the extension of such an interdisciplinary reach by surveying t
he explored and unexplored possibilities that framework nanoparticles can
offer. We localize these unique nanosized reticular materials at the junct
ure between the molecular and the macroscopic worlds\, and describe the re
sulting synthetic and analytical chemistry\, which is fundamentally differ
ent from conventional frameworks. Such differences are mirrored in the pro
perties that reticular nanoparticles exhibit\, which we described while re
ferring to the present state-of-the-art and future promising applications
in medicine\, catalysis\, energy-related applications\, and sensors. Final
ly\, the bottom-up approach of reticular nanoscience\, inspired by nature\
, is brought to its full extension by introducing the concept of augmented
reticular chemistry. Its approach departs from a single-particle scale to
reach higher mesoscopic and even macroscopic dimensions\, where framework
nanoparticles become building units themselves and the resulting super-ma
terials approach new levels of sophistication of structures and properties
LOCATION:Sunstone Bldg / Ground floor / Big Seminar Room B\, ISTA
ORGANIZER:
SUMMARY:Stefan Wuttke: Reticular Nanoscience: Bottom-Up Assembly Nanotechno
logy
URL:https://talks-calendar.ista.ac.at/events/5068
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