Upcoming Seminars & Events

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December 18, 2014
9:00am - 5:00pm
Analysis, Spectra, and Number Theory: A Conference in Honor of Peter Sarnak on his 61th Birthday

The conference will focus on analytic number theory, with emphasis on its many relationships with analysis and spectral theory. Topics to be highlighted include arithmetic quantum chaos, analysis of families of L-functions, arithmetic statistics, and connections with ergodic theory. It will include a problem session to suggest future directions for the field.

For registration and the full list of speakers, see the conference website.

Speaker: ,
Location:
McDonnell Hall A02
December 19, 2014
1:30pm - 2:30pm
TBA - McGibbon
Speaker: Jason McGibbon, University of Massachusetts
Location:
IAS Room S-101
February 2, 2015
4:30pm - 5:30pm
TBA - Barnett
Speaker: Alex Barnett, Dartmouth College
Location:
Fine Hall 214
February 3, 2015
4:30pm - 5:30pm
Height Fluctuations in Interacting Dimers

Perfect matchings of Z^2 (also known as non-interacting dimers on the square lattice) are an exactly solvable 2D statistical mechanics model. It is known that the associated height function behaves at large distances like a massless gaussian field, with the variance of height gradients growing logarithmically with the distance. As soon as dimers mutually interact, via e.g. a local energy function favoring the alignment among neighboring dimers, the model is not solvable anymore and the dimer-dimer correlation functions decay polynomially at infinity with a non-universal (interaction-dependent) critical exponent. We prove that, nevertheless, the height fluctuations remain gaussian even in the presence of interactions, in the sense that all their moments converge to the gaussian ones at large distances. The proof is based on a combination of multiscale methods with the path-independence properties of the height function. Joint work with V. Mastropietro and F. Toninelli.

Speaker: Alessandro Giuliani, University of Rome 3
Location:
Jadwin Hall 343
February 5, 2015
3:00pm - 4:00pm
TBA - Scott
Speaker: Alex Scott, Oxford University
Location:
Fine Hall 224
February 9, 2015
4:30pm - 5:30pm
Disordered Hyperuniform Materials: New States of Matter

While there are four commonly observed states of matter (solid crystal, liquid, gas, and plasma), we have known for some time now that there exist many other forms of matter. For example, both quasicrystals and liquid crystals are states of matter that possess properties that are intermediate between those of crystals and conventional liquids. The focus of my talk will be disordered hyperuniform many-body systems [1], which can be regarded to be new distinguishable states of disordered matter in that they behave more like crystals or quasicrystals in the manner in which they suppress large-scale density fluctuations, and yet are also like liquids and glasses because they are statistically isotropic structures with no Bragg peaks. Thus, disordered hyperuniform systems can be regarded to possess a "hidden order" that is not apparent on short length scales while being structurally rotationally invariant. I will describe a variety of different examples of such disordered states of matter, both equilibrium and nonequilibrium varieties. I will demonstrate that there exist classical ground states that are hyperuniform and disordered in a high-density regime down to some critical density, below which the system undergoes a phase transition to ordered states [2]. Disordered hyperuniform systems appear to be endowed with novel physical properties, including complete photonic band gaps comparable in size to those in photonic crystals [3] and improved electronic band-gap properties. Moreover, we have recently shown that photoreceptor cell patterns (responsible for detecting light) in avian retina have evolved to be disordered and hyperuniform [4].

1. S. Torquato and F. H. Stillinger, "Local Density Fluctuations,
Hyperuniform Systems, and Order Metrics," Phys. Rev. E, 68, 041113 (2003).

2. R. D. Batten, F. H. Stillinger and S. Torquato, "Classical Disordered
Ground States: Super-Ideal Gases, and Stealth and Equi-Luminous
Materials," J. Appl. Phys., 104, 033504 (2008).

3. M. Florescu, S. Torquato and P. J. Steinhardt, "Designer Disordered
Materials with Large, Complete Photonic Band Gaps," Proc. Nat. Acad. Sci.,
106, 20658 (2009).

4. Y. Jiao, T. Lau, H. Haztzikirou, M. Meyer-Hermann, J. C. Corbo, and S.
Torquato, "Avian Photoreceptor Patterns Represent a Disordered
Hyperuniform Solution to a Multiscale Packing Problem," Phys. Rev. E, 89,
022721 (2014).

Speaker: Sal Torquato , Princeton University
Location:
Fine Hall 214
February 12, 2015
3:00pm - 4:00pm
TBA - Parzanchevski
Speaker: Ori Parzanchevski, IAS
Location:
Fine Hall 224
February 12, 2015
4:30pm - 5:30pm
TBA - Baldwin
Speaker: John Baldwin, Boston College
Location:
Fine Hall 314
February 16, 2015
4:30pm - 5:30pm
Hypothesis Testing on Random Networks

I will discuss some new hypothesis testing problems on random graph models. A popular example is the problem of detecting community structure in a graph. Here we will consider more exotic situations, such as testing one of the basic assumption in social network analysis: whether the graph has "geometric structure". We will also talk about dynamical models of random graphs (such as preferential attachment), and how to test different hypotheses on the "history" of these graphs.

Speaker: Sebastien Bubeck, Princeton University - ORFE
Location:
Fine Hall 214
February 23, 2015
4:30pm - 5:30pm
TBA - Sullivan
Speaker: Blair Sullivan, North Carolina State University
Location:
Fine Hall 214
February 24, 2015
4:30pm - 5:30pm
TBA - Subhro Ghosh
Speaker: Subhro Ghosh, Princeton University
Location:
Jadwin Hall 343
March 2, 2015
4:30pm - 5:30pm
TBA - Rafael de la Llave
Speaker: Rafael de la Llave, Georgia Tech
Location:
Fine Hall 214
March 5, 2015
3:00pm - 4:00pm
TBA - Denham
Speaker: Graham Denham, University of Western Ontario
Location:
Fine Hall 314
March 9, 2015
4:30pm - 5:30pm
TBA - Chan
Speaker: Garnet Chan, Princeton University
Location:
Fine Hall 214
March 23, 2015
4:30pm - 5:30pm
TBA - Rebecca Willett
Speaker: Rebecca Willett, University of Wisconsin - Madison
Location:
Fine Hall 214
March 25, 2015
4:30pm - 5:30pm
TBA - Poonen
Speaker: Bjorn Poonen, MIT
Location:
Fine Hall 314
March 30, 2015
4:30pm - 5:30pm
TBA - Laura Waller
Speaker: Laura Waller, UC-Berkeley - Elec. Eng. & Computer Science
Location:
Fine Hall 214
March 31, 2015
4:30pm - 5:50pm
Localization - delocalization transition for particles in random flow
Speaker: Grisha Falkovich, Weizmann Institute
Location:
Jadwin Hall 343
April 2, 2015
3:00pm - 4:00pm
TBA - Wilson
Speaker: Glen Wilson , Rutgers University
Location:
Fine Hall 314
April 7, 2015
4:30pm - 5:30pm
TBA - Wendelin Werner
Speaker: Wendelin Werner, ETH, Zurich
Location:
Jadwin Hall 343

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