# Statistical Mechanics Conference

## 108th Statistical Mechanics Conference

Sunday, December 16, 2012 at 08:00am -

108th List of invited talks and abstracts

108th Short talk schedule

108 SMC presentation of invited talks

## LIST OF INVITED SPEAKERS AND THEIR TALK INFORMATION

**E. Andrei, Rutgers University**

Electronic Cloaking of impurities through Landau level filling in grapheneAbstract: TBA

**M. Anisimov, University of Maryland**

Entropy-driven liquid-liquid transitions in pure substances

Abstract: Twenty years ago Poole et al. [1] suggested that the anomalous properties of supercooled water may be caused by a critical point that terminates a line of metastable liquidÃ¢liquid separation of lower-density and higher-density water. The hypothesized existence of two liquid states in pure water can be globally viewed in the context of liquid polyamorphism, a phenomenon that has been experimentally observed or theoretically suggested in silicon, liquid phosphorus, triphenyl phosphate, and in some other molecular-network-forming substances [2]. We have developed a phenomenological model in which liquid water at low temperatures is viewed as an

thermal solutionof two hydrogen-bond network structures with different entropies and densities [3]. Alternatively to lattice-gas models, in which fluid phase separation is driven by energy, the phase transition in the athermal two-state water is driven by entropy upon increasing the pressure, while the critical temperature is defined by the

reactionequilibrium constant. The order parameter is associated with the entropy, while the ordering field is a combination of temperature and pressure. The model predicts the location of density maxima at the locus of a near-constant fraction of the lower-density structure. Another example of entropy-driven liquid polyamorphism is the transition between the structurally ordered 'Blue Phase III' and disordered liquid in some chiral materials [4]. Thermodynamics of this transition is remarkably similar to that of the hypothesized liquid-liquid transition in supercooled water. However, unlike the metastable transition in supercooled water, the transition between the Blue Phase III and ordinary liquid state is located in the stable region and is experimentally accessible.

- Poole, P. H., Sciortino, F., Essmann, U. & Stanley, H. E.
Phase behaviour of metastable water

, Nature (London) 360, 324 (1992). - McMillan, P. F.
Polyamorphic transformations in liquids and glasses

J. Mater. Chem. 14, 1506 (2004). - Holten, V. & Anisimov, M. A.
Entropy-driven liquid-liquid separation in supercooled water

, Sci. Rep. 2, 713 (2012). http://www.nature.com/scientificreports - Anisimov, M. A., Agayan, V. A. & Collings, P. J.
Nature of the Blue-Phase-III isotropic critical point: An analogy with the liquid-gas transition

, Phys. Rev. E 57, 582-595 (1998).

**J. Banavar, University of Maryland**

- Coathors: Samir Suweis, Filippo Simini, and Amos Maritan

Network architectures of mutualistic ecological communities

- Abstract: TBA

**J. Beamish, University of Alberta, Canada**

Elastic and Plastic Behavior in Solid Helium?

Abstract: TBA

**A. Bertozzi, University of California Los Angeles**

Mathematics of crime

Abstract: There is an extensive applied mathematics literature developed for problems in the biological and physical sciences. Our understanding of social science problems from a mathematical standpoint is less developed, but also presents some very interesting problems, especially for young researchers. This lecture uses crime as a case study for using applied mathematical techniques in a social science application and covers a variety of mathematical methods that are applicable to such problems. We will review recent work on agent based models, methods in linear and nonlinear partial differential equations, variational methods for inverse problems and statistical point process models. From an application standpoint we will look at problems in residential burglaries and gang crimes. Examples will consider both "bottom up'' and "top down'' approaches to understanding the mathematics of crime, and how the two approaches could converge to a unifying theory.

**C. Callan, Princeton University**

TBA

**M. Chan, Pennsylvania State University**

The rise and fall of supersolidity

**J. Chen, University of Waterloo**

"Structures induced from a polymer-membrane interaction: Monte Carlo simulations"

Abstract: Models of self-avoiding polymer chains and fluctuating two-dimensional surfaces have been widely used to provide fundamental understanding of the physical properties of a large variety of synthetic and biological systems. In soft materials (in particular biological materials), linear macromolecules (such as DNA and proteins) and fluctuating surface objects (such as lipid vesicles and cell membranes) are known to coexist and interact with each other. The implications of the interaction between biological polymers and membranes are not only modification of their own physical properties, but sometimes also the yield of profound structural and dynamical properties that are otherwise impossible.

J. Z. Y. Chen, "First-order swollen-to-globular transition of a confined polymer in a soft tube", Phys. Rev. Lett. 98, 088302(2007);

J. Z. Y. Chen, "Model of a polymer chain adsorbed to a soft membrane surface", Phys. Rev. E (R) 82, 060801(2010);

Yu-cheng Su and J. Z. Y. Chen, "Budding transition of a self-avoiding polymer confined by a soft membrane adhering onto a flat wall", to be published (2012).

**P. Constantin, Princeton University**

TBA

**I. Corwin, Clay Mathematics Institute and MIT**

"Integrability in the Kardar-Parisi-Zhang universality class"

Abstract: I will explain the role of quantum integrable systems, bethe ansatz, symmetric function theory and algebraic combinatorics in computing statistics and observables for certain models in the KPZ universality class (include the KPZ equation itself).

**R. Dorfman, University of Maryland**

Jan Sengers- Fifty Years in Nonequilibrium Statistical Physics

Abstract: Starting with his groundbreaking doctoral work, completed in 1962, Jan Sengers continued, and continues, to make fundamental contributions to statistical physics. This talk with give a brief survey of some of his theoretical contributions to the kinetic theory of gases, and nonequilibrium statistical mechanics, as well as his experimental work on transport properties of fluids, including fluids near their critical points and fluids in non-equilibrium stationary states.

**M. Dykman, Michigan State University**

Quantum heating and switching via quantum activation in modulated systems

Abstract: Nonlinear vibrations are attracting interest in many areas, from nanomechanics to circuit and cavity QED to Josephson junctions. They also allow one to address a fairly general problem of quantum fluctuations in systems away from thermal equilibrium. We will show that these fluctuations display unusual features, including the mechanism of switching between coexisting stable states of forced vibrations that has no analog in equilibrium systems. We call it quantum activation. The scaling behavior of the switching rates will be outlined and a comparison with experiment will be made. Fragility of the rates of rare events like interstate switching will be also discussed. Click HERE for extended version of the abstract.

**F. Dyson, Institute for Advanced Studies**

New strategies for prisoner's dilemma

Abstract: TBA

**J-P. Eckmann, University of Geneva**

Non-equilibrium steady states for networks of springs

Abstract: The theory of non-equilibrium steady states is fairly well understood for the case of 1-dimensional systems of masses connected by harmonic and an-harmonic springs. In this talk I discuss the extensions to a set of more complicated networks of connections. These include *n*-dimensional slabs which are connected to heat baths at their ends. Under an explicit genericity assumptions on the couplings, arbitrary networks can be treated.

The arguments are based on controllability and conditions on the spring potentials at infinity. I will focus my talk on the controllability.

**P. Fendley, University of Virginia**

"Exact and simple results for the XYZ spin chain"

Abstract: Long ago, Onsager, Kaufman and Yang computed the spontaneous magnetization in the Ising model. Their result is remarkable not only in that it can be computed exactly, but in that the resulting formula is extremely simple. I will explain how similar results occur in models without free-fermion structure as well, for example in the XYZ spin chain when the couplings obey

J_{_}x J_{_}y + J_{_}y J_{_}z + J_{_}x J_{_} z = 0. I will also explain how a hidden supersymmetry plays a crucial role.

**E. Fort, ESPCI, Paris**

Statistical properties of path-memory driven dual objects

Abstract: We have recently discovered a macroscopic object composed of a material particle dynamically coupled to a wave packet. The particle is a droplet bouncing on the surface of a vertically vibrated liquid bath; its pilot-wave is the result of the superposition of the surface waves it excites. Above an excitation threshold, this symbiotic object, designated as a walker

becomes self-propelled. Click HERE for the full abstract.

**P. Fratzl, Max Planck Institute of Colloids and Interfaces**

Coauthors: P. Fratzl, M. J. Harrington, F. D. Fischer

"Modeling the phase transformation which controls the mechanical behavior of a protein filament"

Abstract: Some protein-based fibers, as found for example in the egg-shell of the marine whelk, require a combination of stiffness and extensibility to protect the organism. In whelk egg-case, the protein is initially kept by a large number of weak bonds in a relatively compact conformation with high stiffness. The fiber is then able to extend by transformation of the protein into a much more extended conformation in a process similar to a phase transformation. X-ray diffraction reveals the coexistence of the low-strain and the high-strain conformations in a proportion defined by the applied force. The process is modeled using well-known theories of phase transformation in materials.

**J. Frohlich, ETH Zurich **

Dissipative Motion from a Hamiltonian Point of View

Abstract: I will describe a system consisting of a tracer particle interacting with a dispersive wave medium; (one may think of a heavy particle moving through a dense Bose gas at zero temperature, in the limit of very large particle mass and very large gas density). This is an example of a Hamiltonian system with infinitely many degrees of freedom that describes dissipative phenomena. One can show that a friction force with memory acts on the particle and causes it to decelerate. Friction is due to the particle's emission of Cherenkov radiation of sound waves into the gas. For an ideal Bose gas, the particle decelerates until it comes to rest. Time permitting, some applications of these results to mechanisms of decoherence are pointed out.

**G. Gallavotti, Universita di Roma La Sapienza & Rutgers University**

Formal perturbation analysis of a non equilibrium stationary state

Abstract: System considered is a simple rotator subject to a consrvative force, a constant torque and a random forcing (Langevin type). The possible expansion o the stationary state in powers of the conservative force strength is discussed.

**C. Giardina, University of Modena and Reggio Emilia**

"Exactly solvable diffusions and heat conduction"

Abstract: I will discuss a model of interacting diffusions for heat conduction. The model has an underlying SU(1,1) algebraic structure which makes it solvable by duality. A full control of correlation functions, showing long-range behavior typical of non-equilibrium systems, is obtained and the relevance of the model to the problem of Fourier law is discussed. If time permits, I will also show applications of the model to population genetics.

**R. Goldstein, Cambridge University**

"Shape of a Ponytail and the Statistical Physics of Hair Fiber Bundles"

Abstract: A bundle of hair, whether a paintbrush or a ponytail, adopts a shape determined by the interplay of the stiffness and weight of the individual fibers and their intrinsic waviness or curliness. Since a typical bundle may have ten thousand individual hairs, each with a distinct profile of intrinsic curvatures, the determination of its shape is a problem in the statistical physics of disordered systems. In work with Patrick B. Warren and Robin C. Ball we have developed a variational theory for the properties of hair bundles. The theory is based on the local density and mean orientation of hairs, with the effects of random curvatures subsumed into a local energy functional. This decomposition reveals how the concept of an `equation of state' of hair appears naturally in the force balance that governs the equilibrium shape of the bundle. Specializing to long, narrow, axisymmetric bundles, an ansatz of self-similarity allows the many-body problem to be reduced to an equivalent single-fiber one for the envelope of the bundle. The interplay between filament stiffness and weight, and the pressure arising from random curvatures defines two main regimes of ponytail shapes, and a matched asymptotic analysis that links them. This reduction in turn allows the equation of state of hair to be determined from measurements of ponytail shapes. A robust image-processing method for determining the three-dimensional shapes of individual hairs and a procedure for extracting the envelope of a bundle are described in detail. Measurements of those properties for commercially-available hair switches are presented, and it is shown that the equation of state thus determined is essentially Hookean, with a spring constant determined by the bending elasticity and the spectrum of random curvatures of individual fibers.

**D. Hekstra, University of Texas Southwestern**

Making histories: population fluctuations in replicate closed ecosystems

Abstract: TBA

**M. Kardar, MIT**

Polymer-mediated entropic forces between scale-free objects

Abstract: The number of configurations of a polymer is reduced in the vicinity of a barrier; the resulting loss of entropy leading to a repulsive force. When the obstacles are scale invariant shapes (such as cones, wedges, lines or planes) the only relevant length scales are the polymer size R and characteristic separations, severely constraining the functional form of entropic forces. Specifically, we consider a polymer (single strand or star) attached to the tip of a cone, at a separation h from a surface (or another cone). At close proximity, such that h « R, separation is the only remaining relevant scale and the entropic force must take the form F = A kT /h. The amplitude A is universal, and can be related to exponents ? governing the anomalous scaling of polymer correlations in the presence of obstacles. We use analytical, numerical and epsilon-expansion techniques to compute the exponent ? for a polymer attached to the tip of the cone (with or without an additional plate or cone) for ideal and self-avoiding polymers. The entropic force is of the order of 0.1pN at 0.1?m for a single polymer, and can be increased for a star polymer.

**M. Kastner, National Institute for Theoretical Physics - Wallenberg Research Centre **

"Relaxation timescales in closed long-range quantum spin models"

Abstract: The approach to equilibrium is studied for long-range quantum Ising models where the interaction strength decays like $r^{-alpha}$ at large distances $r$. For a class of initial states, expectation values are found to show a Gaussian decay in time. In a certain regime of the exponent $alpha$, the corresponding relaxation times exhibit a non-trivial system size dependence. Increasing the long-range character of the interactions beyond a certain threshold, relaxation takes place in two steps on two widely separated time scales, showing pronounced prethermalization plateaus. Specializing to a triangular lattice in two spatial dimensions, these results can be used for benchmarking of an ion-trap based quantum simulator.

**H. Kojima, Rutgers University**

Simultaneous Measurements of Torsional Oscillation and 10 MHz Ultrasound Propagation in Solid He-4 at Low Temperatures

Abstract: The superfluidity interpretation of the observed anomalous increases in the frequencies of torsional oscillators (TO) containing solid He-4 samples has come under serious questions. Our work is motivated to search for possible signatures in ultrasound propagation that may be correlated with the TO anomaly. Ultrasound propagation in solid He-4 is sensitive to the presence of dislocation lines which have been proposed as a possible origin of the observed TO anomaly. Observations of sharp changes in the propagation velocity and attenuation of ultrasound at the same temperature as the TO anomaly will be presented.

**D. Lathrop, University of Maryland**

"Characterization of Quantized Vortices in Superfluid Helium"

Abstract: Turbulence in superfluid 4-Helium is dominated by reconnection and ring collapse or quantized vortices. We utilize micron and nano-scale ice particles to visualize the dynamics of quantized vortices and the normal component. After briefly reviewing our observations of these phenomena, I will discuss reconnection dynamics at large and small scales. Those dynamics might be tested against similarity solutions of different current competing theoretical models.

**S. Leibler, Rockefeller University**

TBA

**H. Levine, Rice University**

Cell Motility - getting from the individual to collective tissue motion

Abstract: Eukaryotic cells crawl by the coordinated dynamics of their cytoskeletal proteins, especially actin and myosin. This coordination can be controlled by external signals such as chemical gradients, the nature of the substrate, and their interactions with other cells. This talk will sketch our recent work on constructing biophysical models of individual and collective cell motility, especially including recent efforts to explain tissue dynamics experiments by Trepat et al by invoking coupling between cellular polarization and overall cell velocity.

**B. Mulder, FOM Institute AMOLF**

Taking directions: Principles of self-organisation in the plant cortical array

Abstract: The majority of plant cells grow by expansion along single axis. To control this direction they employ a unique intracellular structure, the so-called transverse array. A dynamic network of microtubules bound to inside of the plasma membrane self-organizes into this highly aligned and robustly oriented non-equilibrium steady state. We have developed both an analytical model as well as an event-driven simulation scheme to elucidate how collisions between the dynamic microtubules lead to the observed ordering, uncovering a molecular-level selection mechanism we have dubbed "survival of the aligned".

**A. Panagiotopoulos, Princeton University**

Anisotropic Structures from Isotropic Building Blocks: Grafted Nanoparticle Systems

Abstract:It is easy to understand the self-assembly of particles with anisotropic shapes or interactions into highly extended structures. However, there is no established strategy for creating a range of anisotropic structures from common spherical nanoparticles. We focus here on the possibility to obtain stable two-dimensional patterns of spherically grafted nanoparticles when suspended as a free-standing film. Morphological phase diagrams in terms of particle particle and particle-polymer attractions are systematically studied for nanoparticles with different grafted chain lengths. We observe morphologies ranging from dispersed particles, finite stripes to percolating networks. Although the formation of stripes for this system is generally understood to be linked to the grafted chain deformation upon aggregation of the particle cores, resulting in an effective anisotropic interparticle potential, we find that anisotropic self-assembly can be reproduced by coarse-graining the interactions into 2-dimensional isotropic potentials obtained by a simple inverse-Boltzmann procedure.

**I. Procaccia, The Weizmann Institute of Science**

"Plasticity and Shear Bands in Amorphous Solids"

Abstract: I will present the unfolding theory of what is plasticity and how to predict mechanical yielding in amorphous solids. The theory is based on understanding the zero-temperature and quasistatic conditions but then evolves to finite temperatures and finite strain rates. In particular it will be shown how to predict the zero-temperature value of external strain where shear-banding can occur,and how to derive the Johnson-Samwer T^{{2/3}} law for the temperature dependent yield stress.

**M. Rigol, Georgetown University**

"Nonequilibrium dynamics of a quasi-disordered quantum system after a quench"

Abstract: After a sudden quench, the dynamics and thermalization of isolated quantum systems are topics that have generated increasing attention in recent years. This is in part motivated be the desire of gaining a deeper understanding of how statistical behavior emerges out of the unitary evolution in isolated quantum systems and in part by novel experiments with ultracold gases. For integrable systems, several studies have found that the unitary dynamics does not lead to thermal expectation values of observables after relaxation. However, those expectation values can still be described utilizing generalized ensembles, which take into account the existence of relevant sets of conserved quantities. In this talk, we discuss how a delocalization-to- localization transition in an integrable (quasi-)disordered quantum system changes the picture above. In the localized regime, we show that some observables equilibrate while others fail to do so. In addition, standard generalized ensembles fail to describe observables after equilibration.

**S. Sachdev, Harvard University**

Conformal field theories in 3 dimensions, and holography

Abstract: I will review basic aspects of the connection between conformal field theories in 2+1 dimensions and gravity theories on AdS_4. I will show how these methods allow computation of non-zero temperature transport properties near quantum phase transitions of experimental interest.

**M. Sano, Tokyo University**

Directed Percolation and Transition to Turbulence in Sheared Liquid Crystals

Abstract: Dynamics of topological defects in liquid crystals plays important roles in phase ordering dynamics and transition to a "turbulent state" mediated by defects. Because of easy accessibility to a large aspect ratio and visualization of defects, liquid crystal is an ideal experimental system for studying nonequilibrium transition phenomena. We characterized decaying or surviving processes of turbulent patches injected from the upstream of a flowing liquid crystal to mimic the onset of shear flow turbulence such as in a pipe flow or Poiseuille flow. After briefly reviewing our previous results on directed percolation (DP) experiment in liquid crystal without shear flow, I will explain how the DP-like behavior is modified or not modified in the presence of shear flow. It is turned out that the critical condition for the DP transition is reduced with increasing the shear rate and eventually a different type of transition to an absorbing state can be observed. The transitions to an absorbing state in this shear flow system are characterized in a two parameter phase diagram.

**T. Sasamoto, Chiba University **

"The stationary correlations of the 1D KPZ equation"

Abstract: The Kardar-Parisi-Zhang (KPZ) equation, which was introduced in 1986 to describe surface growth phenomena, has been considered to be one of the most basic equation in non-equilibrium statistical physics and has been studied extensively by various methods such as the dynamical renormalization group, mode-coupling etc. Two years ago, the first exact solution was obtained for the one-dimensional version with narrow wedge initial condition[1]. Since then several generalizations have been obtained.

In this talk after reviewing these developments, we present our results of the height distribution and the two point correlation function for the KPZ equation in the steady state[2]. We explain basic ideas for the derivation based on the replica method and discuss its importance.

[1] T. Sasamoto and H. Spohn, Phys. Rev. Lett. 104, 230602 (2010), G. Amir, I. Corwin, J. Quastel, Comm. Pure Appl. Math., 64, 466-537 (2011).

[2] T. Imamura, T. Sasamoto, Phys. Rev. Lett. 108, (2012), arXiv:1210.4278.

**R. Seiler, Technische Universitaet Berlin **

The Quantum Sanov Theorem: A Cradle for Fundamental Results in Information Theory

Abstract: TBA

**E. Stanley, Boston University**

The fragilityof interdependency: Coupled networks and switching phenomena

Abstract: Recent disasters ranging from abrupt financial flash crashes

and large-scale power out- ages to sudden death among the elderly dramatically exemplify the fact that the most dangerous vulnerability is hiding in the many interdependencies among different networks. In the past year, we have quantified failures in interconnected networks, and demonstrated the need to consider mutually dependent network properties in designing resilient systems. Specifically, we have uncovered new laws governing the nature of switching phenomena in coupled networks, and found that phenomena that are continuous second order

phase transitions in isolated networks become discontinuous abrupt first order

transitions in in- terdependent networks [S. V. Buldyrev, R. Parshani, G. Paul, H. E. Stanley, and S. Havlin, Catastrophic Cascade of Failures in Interdependent Networks,

Nature 464, 1025 (2010); J. Gao, S. V. Buldyrev, H. E. Stanley, and S. Havlin, Novel Behavior of Networks Formed from Interdependent Networks,

Nature Physics 8, 40 (2012). We conclude by discussing the network basis for understanding sudden death in the elderly, and the possibility that financial Ã¢flash crashesÃ¢ are not unlike the catastrophic first-order failure incidents occur- ring in coupled networks. Specifically, we study the coupled networks that are responsible for financial fluctuations. It appears that trend switching phenomena

that we uncover are remarkably independent of the scale over which they are analyzed. For example, we find that the same laws governing the formation and bursting of the largest financial bub- bles also govern the tiniest finance bubbles, over a factor of 1,000,000,000 in time scale [T. Preis, J. Schneider, and H. E. Stanley, Switching Processes in Financial Markets,

Proc. Natl. Acad. Sci. USA 108, 7674 (2011); T. Preis and H. E. Stanley, Bubble Trouble: Can a Law Describe Bubbles and Crashes in Financial Markets?

Physics World 24, No. 5, 29 (May 2011)]. This work was carried out in collaboration with a number of colleagues, chief among whom are T. Preis (Mainz & ETH), J. J. Schneider (Mainz), S. Havlin & R. Parshani (Bar-Ilan), S. V. Buldyrev (Yeshiva U), J. Gao & G. Paul (BU).

**D. Stein, New York University**

Thermal Fluctuations and Nanowire Stability

Abstract: In classical field theories subject to a small, externally applied noise, a crossover between different activation behaviors can occur as one or more control parameters is varied. This crossover has some (but not all) features of a second-order phase transition, and shares a number of features with the well-known crossover from thermally activated hopping to quantum tunneling through a barrier as temperature is lowered in certain quantum field theories. While the mathematics of such systems are interesting in themselves, they also have applications to systems at the mesoscopic and nanoscopic scales. I will discuss one such application, to thermally induced breakup of monovalent metallic nanowires, emphasizing the connection to recent (and not so recent) experiments as well as the possibility of new nanoscopic devices.

**J. Ortiz Zarate, Universidad Complutense Madrid**

"Fluctuating hydrodynamics for nonequilibrium steady states"

Abstract: The application of fluctuating hydrodynamics to study the spatiotemporal evolution of thermal fluctuations in nonequilibrium steady states is reviewed. The important contributions of Jan Sengers to this field in the last decades, both experimental and theoretical,Â are emphasized. Some basic ideas, such as what is the more fundamental formulation of the fluctuation-dissipation theorem arise naturally, and will be open for discussion.

**J. Zhang, NYU**

Thermal convection with mobile boundaries: experimental attempts to simulate continental dynamics

Abstract: Thermal convection, which is ubiquitous in nature, has been one of the most studied dynamical systems in the past 30 years. There, a fluid that is confined within rigid boundaries is cooled at the top and heated from below becomes unstable as the imposed temperature difference is sufficiently large. If one of the confining boundaries is mobile, subject to the viscous drag of the fluid flow, the dynamics of the coupled system may exhibit some surprising behaviors (e. g. oscillation and localization). I will discuss the possible connection between this system and the geophysical process of continental drift.

**W. Zhang, University of Chicago**

"Still water Dead zones and collimated ejecta from the impact of granular jets"

Abstract: Children learn that liquids are an intermediate state of matter: like gases, they flow easily but, like solids, they exist in a condensed state due to inter-particle attractions. In graduate school they may be taught that liquids can be simulated without attractions if the particle density is kept high by confinement. However, even without attractions or confinement, non-cohesive particles can behave like a liquid: when a high-density jet of grains hits a target it ejects particles in a thin sheet similar to the water bells created by liquid-jet impact. Our experiments, simulations and continuum modeling show that such ejecta sheets are generic and independent of the jet's internal kinematic features and the target shape. We show that this insensitivity arises because,surprisingly, the highly dissipative dense granular jet impact is controlled by the limit of perfect fluid flow. In contrast with the expectation that scattering provides sufficient information to reconstruct the internal state, the macroscopic observables, e.g., thin-sheet ejection angle, give little information about the jet dynamics when the density is high.

## PRESENTATIONS OF TALKS GIVEN AT THE 108th STATISTICAL MECHANICS CONFERENCE

M. Anisimov, University of MarylandEntropy-Driven Liquid-Liquid Transitions in Pure Substances

S. Buldyrev, Yeshiva University

The Fragility of Interdependency: Coupled Networks and Switching Phenomena

I. Corwin, Clay Mathematics Institute and MIT

Integrability in the Kardar-Parisis-Zhang Universality class

M. Dykman, Michigan State University

Quantum heating and switching via quantum activation in modulated systems

J.P. Eckmann, University of Geneva

Non-equilibrium steady states for networks pf springs

P. Fendley, University of Virginia

The uses of topology for spin systems

P. Fratzl, Max Planck Institute for Colloids and Interfaces

Modeling the phase transformation which controls the mechanical behavior of a protein filament

J. Froehlich, ETH Zurich

Dissipative motion from a hamiltonian point of view

G. Gallavotti, University of Rome

Formal perturbation analysis of a non equilibrium stationary state

C. Giardina, University of Modena and Reggio Emilia

Exactly solvable diffusions and heat conduction

R. Goldstein, Cambridge University

Shape of a ponytail and the statistical physics of hair fiber bundles

Tribute to Harry Swinney by R. Goldstein

D. Hekstra, University of Texas, Southwestern

Making histories: population fluctuations in replicate closed ecosystems

M. Kardar, MIT

Polymer-mediated entropic forces between scale-free objects

M. Kastner, National Institute for Theoretical Physics

Relaxation timescales in closed long-range quantum spin models

H. Kojima,Rutgers University

Simultaneous measurements of torsional oscillation and 10 MHz ultrasound propogation in solid He-4 at low temperatures

J. Ortiz, Universidad Complutense Madrid

Fluctuating hydrodynamics for nonequilibrium steady states

M. Rigol, Georgetown University

Nonequilibrium dynamics of a quasi-disordered quantum system after a quench

T. Sasamoto, Chiba University

The stationary correlations of the ID KPZ equation

D. Stein, New York University

Thermal fluctuations and Nonowire Stability