Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session F40: Leo Kadanoff Session II / GSNP Student Awards 
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Sponsoring Units: GSNP DCMP Chair: Susan Coppersmith, Bulbul Chakraborty, University of Wisconsin, Brandeis University Room: 343 
Tuesday, March 15, 2016 11:15AM  11:27AM 
F40.00001: Fractions, trees and unfinished business. Boris Shraiman In this talk, mourning the loss of a teacher and a dear friend, I would like to share some unfinished thoughts loosely connecting  via Farey fraction trees  Kadanoff's study of universality of quasiperiodic route to chaos with the effort to understand universal features of genealogical trees. [Preview Abstract] 
Tuesday, March 15, 2016 11:27AM  11:39AM 
F40.00002: A potential mechanism for a singular solution of the Euler Equations Michael Brenner, Sahand Hormoz, Alain Pumir We describe a potential mechanism for a singular solution of the Euler equation. The mechanism involves the interaction of vortex filaments, but occurs sufficiently quickly and at small enough scales that it could have plausibly evaded experimental and computational detection. Scaling estimates for the characteristics of this solution will be presented, as well as numerical simulations of the initial stages. [Preview Abstract] 
Tuesday, March 15, 2016 11:39AM  11:51AM 
F40.00003: Nonlinear dynamics of a strongly driven single spin solid state qubit~ S. N. Coppersmith, Thibaut Jullien, P. Scarlino, E. Kawakami, D. R. Ward, D. E. Savage, M. G. Lagally, Mark Friesen, M. A. Eriksson, L. M. K. Vandersypen This talk will discuss how dynamical systems theory can yield new insight into some exotic behavior found in experiments on strongly driven quantum spins in silicon/silicongermanium heterostructures. ~Spin resonance experiments were performed by using ac voltages to drive an electron wavefunction in a strong magnetic field gradient. ~Nontrivial dependence of the resonance frequency on applied power, including the observation of multiple resonant frequencies at one power, are shown to be consistent with frequencydependent attenuation in the highfrequency lines. ~The method of analysis is very similar to that presented in the course on nonlinear dynamics that Leo Kadanoff developed at the University of Chicago in the early 1990's. [Preview Abstract] 
Tuesday, March 15, 2016 11:51AM  12:03PM 
F40.00004: Learning in a noisy environment: a Lyapunov equation approach Sara A Solla, Yarden Cohen, Predrag Cvitanovic Consider a behavioral task described as a finite time trajectory through a $d$dimensional space, segmented in $K$ time steps, and thus fully specified by a vector $X$ in the $n=dK$ dimensional state space of possible trajectories. Consider the dynamics of learning a desired target trajectory $X^{*}$. In the vicinity of $X^{*}$, the learning dynamics at the $t$th discrete learning time step can be linearized to $Y_{t+1}=M Y_{t}+\xi_{t}$, where, $Y_{t}=X_{t}X^{*}$ and $\xi$ is independent Gaussian noise of zero mean and covariance $\Delta$. The balance between contracting dynamics and noise leads to an asymptotic covariance $Q$ that obeys the Lyapunov equation $Q=M Q M^T+\Delta$. Given $Q$, how can the unknown deterministic component $M$ be estimated the presence of noise? We propose the use of systematic target perturbations $X^{*} \to X^{*}+\epsilon V_j$, with unit vectors $V_j$, $1 \le j \le n$ that span the space $X$. We argue, convincingly if not rigorously, that the linear response to these perturbations fully characterizes the asymptotic dynamics of the learning process. We illustrate the method by analyzing networks of neurons with either intrinsic or extrinsic noise, at time resolutions that span from spike timing to spiking rates. [Preview Abstract] 

F40.00005: ABSTRACT WITHDRAWN 
Tuesday, March 15, 2016 12:15PM  12:27PM 
F40.00006: Nonlinear dynamics, Waddington landscape and stem cells Chao Tang There are hundreds of different cell types (skin, neuron, muscle, etc.) in human body, all derived from the stem cell and all have the same genetic information. About 60 years ago, Waddington speculated that the different cell types correspond to different minima in a landscape emerged from genetic interactions. Recently, biologists succeeded in transforming one cell type to another by perturbing the genetic interactions in a cell. I will discuss the experiments and a mathematical model of a set of such cell type transformations in mice, in which we can see an actual example of the Waddington landscape and ways to alter it to facilitate cell type transformation  in particular, to reprogram a differentiated cell back into a stem cell. [Preview Abstract] 
Tuesday, March 15, 2016 12:27PM  12:39PM 
F40.00007: From Glaciers to Icebergs Wendy Zhang I will describe works from a collaboration between physics and glaciology that grew out of interactions at the {\it Computations in Science} seminar Leo Kadanoff organized at the University of Chicago. The first project considers the interaction between ocean waves and Antarctic ice shelves, large floating portions of ice formed by glacial outflows. Backofenvelop calculation and seismic sensor data suggest that crevasses may be distributed within an ice shelf to shield it from wave energy. We also examine numerical scenarios in which changes in environmental forcing causes the ice shelf to fail catastrophically. The second project investigates the aftermath of iceberg calving off glacier terminus in Greenland using data recorded via timelapse camera and terrestrial radar. Our observations indicate that the mÃ©lange of icebergs within the fjord experiences widespread jamming during a calving event and therefore is always close to being in a jammed state during periods of terminus quiescence. Joint work with Jason Amundson, Ivo R. Peters, Julian Freed Brown, Nicholas Guttenberg, Justin C Burton, L. Mac Cathles, Ryan Cassotto, Mark Fahnestock, Kristopher Darnell, Martin Truffer, Dorian S. Abbot and Douglas MacAyeal. [Preview Abstract] 
Tuesday, March 15, 2016 12:39PM  12:51PM 
F40.00008: Multifractals, random walks and Arctic sea ice Sahil Agarwal, John Wettlaufer We examine the longterm correlations and multifractal properties of daily satellite retrievals of Arctic sea ice albedo, extent, and ice velocity for decadal periods. The approach harnesses a recent development called Multifractal Temporally Weighted Detrended Fluctuation Analysis (MFTWDFA), which exploits the intuition that points closer in time are more likely to be related than distant points. In both data sets we extract multiple crossover times, as characterized by generalized Hurst exponents, ranging from synoptic to decadal. The method goes beyond treatments that assume a single decay scale process, such as a firstorder autoregression, which cannot be justifiably fit to these observations. The ice extent data exhibits white noise behavior from seasonal to biseasonal time scales, whereas the clear fingerprints of the short (weather) and long ($\sim$ 7 and 9 year) time scales remain, the latter associated with the recent decay in the ice cover. Thus, long term persistence is reentrant beyond the seasonal scale and it is not possible to distinguish whether a given ice extent minimum/maximum will be followed by a minimum/maximum that is larger or smaller in magnitude. The ice velocity data show long term persistence in auto covariance. [Preview Abstract] 
Tuesday, March 15, 2016 12:51PM  1:03PM 
F40.00009: Phase transition to turbulence in a pipe Nigel Goldenfeld Leo Kadanoff taught us much about phase transitions, turbulence and collective behavior. Here I explore the transition to turbulence in a pipe, showing how a collective mode determines the universality class. Near the transition, turbulent puffs decay either directly or through splitting, with characteristic timescales that exhibit a superexponential dependence on Reynolds number. Direct numerical simulations reveal that a collective mode, a socalled zonal flow emerges at large scales, activated by anisotropic turbulent fluctuations, as represented by Reynolds stress. This zonal flow imposes a shear on the turbulent fluctuations that tends to suppress their anisotropy, leading to a Landau theory of predatorprey type, in the directed percolation universality class. Stochastic simulations of this model reproduce the functional form and phenomenology of pipe flow experiments. Talk based on work performed with HongYan Shih and TsungLin Hsieh. [Preview Abstract] 
Tuesday, March 15, 2016 1:03PM  1:15PM 
F40.00010: Material Flows in an Active Nematic Liquid Crystal Stephen DeCamp 
Tuesday, March 15, 2016 1:15PM  1:27PM 
F40.00011: Lie Algebraic Analysis of Thin Film Marangoni Flows: Multiplicity of SelfSimilar Solutions Zachary Nicolaou 
Tuesday, March 15, 2016 1:27PM  1:39PM 
F40.00012: Ordertochaos transition in the hardness of random Boolean satisfiability problems Melinda Varga . [Preview Abstract] 
Tuesday, March 15, 2016 1:39PM  1:51PM 
F40.00013: HamiltonianBased Model to Describe the Nonlinear Physics of Cascading Failures in PowerGrid Networks Yang Yang 
Tuesday, March 15, 2016 1:51PM  2:03PM 
F40.00014: Cell fate reprogramming by control of intracellular network dynamics Jorge G.T. Zanudo 
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