Ludovic Berthier: Universal nature of particle displacements close to the glass transition "Dynamic heterogeneity in glassy materials has been extensively studied in the last decade because it reveals detailed informations about the relevant spatio-temporal fluctuations characterizing the slow dynamics in these materials. The self-part of the van Hove function, that is, the probability distribution function of particles displacements, Gs(r,t), attracts renewed interest because it is directly accessible in dense colloidal systems via microscopy techniques. Surprisingly, this function has received little attention from theoreticians beyond its qualitative description. Revisiting numerical and experimental data, we have discovered that Gs(r,t) displays a simple and universal behaviour near the glass transition. I will present convincing evidence for this behaviour and introduce and solve a generic model to explain both the shape and the temperature evolution of the data in a variety of glass-formers."

Alexander Burin: Theory of slow relaxation in amorphous solids induced by external electric field. Applications to dielectric constant and hopping conductivity TBA

Horacio Castillo: Fluctuations in the aging of structural glasses "The presence of dynamical heterogeneities is increasingly being recognized as a crucial factor in the understanding of the glass transition. However a clear physical picture for the origin of these heterogeneities is still lacking. Here we present a detailed numerical study of fluctuations in the aging regime of a simple binary Lennard-Jones glass former. A possible physical mechanism for the origin of dynamical heterogeneities in the non-equilibrium dynamics of glassy systems predicts universal scaling of the probability distributions of two-time local fluctuations, and this scaling is indeed approximately satisfied by our data. We also discuss the dynamical spatial correlations in the aging regime, and find that for most waiting times $t_w$ and final times $t$, both the dynamical susceptibility $\chi_4(t,t_w)$ and the dynamical correlation length $\xi_4(t,t_w)$ can be approximated as products of two factors: i) a waiting time dependent scale and ii) a scaling function dependent on $t,t_w$ only through the value of the intermediate scattering function $C(t,t_w)$."

Claudio Chamon: Universality in glassy dynamics "Do we really need to fully answer why glasses form before we better understand glassy dynamics? In this talk we explore the point of view that, by starting from the fact that glassy systems exist (as nature presents us with concrete examples), we can then attempt to characterize whatever possible universal properties there are in glassy dynamics by exploring dynamical symmetries (see also the talk by L. Cugliandolo). We analyze scale invariance, and a larger symmetry, reparametrization invariance, and their implications to dynamical heterogeneities in glassy systems. We test the implications of the symmetry principle using numerical simulations."

Marek Cieplak: Two-state behavior in an exact model of protein folding "We present the results of an exact analysis of a model energy landscape of a protein [1] to clarify the notion of the transition state and the physical meaning of the phi values determined in protein engineering experiments. We benchmark our findings to various theoretical approaches proposed in the literature for the identification and characterization of the transition state. [1] I. Chang, M. Cieplak, J.R. Banavar, and A. Maritan, Protein Science 13, 2446 (2004)"

Leticia Cugliandolo: Dynamic fluctuations in glassy and simple coarsening systems "In recent years it became clear that dynamic spatio-temporal fluctuations in glassy systems, either in the super-cooled liquid or the glass, are especially important. In this talk I shall briefly discuss an analytic approach to this problem based on time-reparametrization symmetry (see also the talk by C. Chamon); I shall describe results from numerical simulations use to put this analytic approach to the test; and I shall confront certain aspects of the mesoscopic dynamics of glasses to the one of simpler coarsening phenomena."

Mark Ediger: Dynamics of polymer glasses during active deformation "Polymer glasses can often be deformed significantly without breaking. What microscopic mechanism allows this flow under conditions where mobility is otherwise absent? We utilize an optical photobleaching technique to measure the segmental mobility of polymer glasses active deformation. It has been previously established that the reorientation of dilute dye molecules (on the time scale of thousands of seconds) can monitor the segmental dynamics of a polymer melt. Here we utilize this method to measure mobility during tensile deformation of a free-standing poly(methyl methacrylate) glass. We have observed increases in mobility during deformation from Tg-10 K to Tg -30 K, with larger changes at lower temperatures. At Tg-22 K, with a stress of 16 MPa, segmental mobility increases slowly at first and then dramatically, so that the increase in mobility during deformation reaches a factor of about 600. After removing the stress, we observe that the enhanced mobility disappears slowly. These measurements are compared to continuum and mesoscopic models of polymer glass dynamics and rheology."

Michael Falk: The Statistical Mechanics of Strain Localization in Metallic Glasses "Metallic glasses represent a promising high strength material, but their use is limited by the onset of a shear banding instability when their material strength is exceeded. Recent simulation studies of the initiation and development of localized deformation in molecular dynamics simulations of a number of amorphous systems reveal the structural changes that accompany plastic deformation and localization involve a decrease in the local short range ordering. We have simulated both two-dimensional and three-dimensional systems in nanoindentation [1], uniaxial tension [2] and compression [3] in plane strain. The degree of strain localization depends sensitively on the quench rate during sample preparation, with localization only arising in more gradually quenched samples. A systematic analysis of simulated systems in simple shear geometries [4] reveals that a Boltzmann-like relationship between strain rate and structure holds over large variations in both the applied strain rate and the initial structural state of the glass. Scaling is observed over eight orders of magnitude in strain rate. The consequences of this scaling for constitutive models of glass plasticity will be discussed. [1] Y. Shi and M.L. Falk, “Structural transformation and localization during simulated nanoindentation of a non-crystalline metal film,” Applied Physics Letters, Vol. 86, pp. 011914 (2005). [2] Y. Shi and M.L. Falk, “Strain localization and percolation of stable structure in amorphous solids,” Physical Review Letters, Vol. 95, pp. 095502 (2005). [3] Y. Shi and M.L. Falk, “Atomic-scale simulations of strain localization in three-dimensional model amorphous solids,” Physical Review B, Vol. 73, pp. 214201 (2006). [4] Y. Shi, M.B. Katz, H. Li and M.L. Falk, “Evaluation of the ‘disorder temperature’ and ‘free volume’ formalisms via simulations of shear banding in amorphous solids,” submitted."

Andreas Fleischmann: TBA TBA

Peter Harrowell: The Spatial Character of Irreversible Relaxation in a Supercooled Liquid "The defining feature of structural and mechanical relaxation in a dense phase is its effective irreversibility. In this paper we use molecular dynamics simulations of a glass-forming liquid to study the spatial distribution of irreversible reorganization."

Bela Joos: Microstructure and aging of a polymer glass subjected to instantaneous shear strains "The application of instantaneous shear deformations on a polymer glass modifies the energy landscape of the glass in non-trivial ways. Using molecular dynamics simulations on a freely-jointed chain model, we investigate the effect of the strain on the heterogeneities in the glassy system. The resulting behaviour can be separated into two regimes: elastic for small shear deformations, and plastic for large deformations. Dynamic heterogeneity in the system tends to diminish with deformation. The increased homogenization can be seen, for instance, through changes in the distribution of particle mobilities, both in space and in time, as the glass relaxes following an affine deformation. The evolution of the local stresses were correlated to the local diffusion constants and used to discuss the evolution of the energy landscape. The effect of the deformation on the aging process will also be addressed, as we present some new insight into the local structure and dynamics of the glassy state."

Maria Kilfoil: Direct observation of dynamical heterogeneities near the attraction-driven glass "Dynamical heterogeneity is believed to be the origin of the slow structural relaxations that take place in molecular glasses, and in model systems such as colloidal glasses and gels. In hard sphere liquids close to the glass transition, structural relaxation has been shown to take place through highly-correlated string-like motion of a few mobile particles, with the dynamical heterogeneity related to heterogeneity in the local density. There is mounting evidence that the different pathways to solidification brought about by crowding in hard spheres and by interparticle attraction in attractive systems might all be due to increased steric hindrance followed by glassy behavior at the onset of solidification. In this talk I will show the microscopic dynamics of a suspension of colloids with attractive interaction by confocal fluorescence microscopy. We study the distinct and self parts of the van Hove density-density correlation function applied to our experimental data. Separable fast and slow populations emerge in the self part, while the distinct part shows a pronounced signature of dynamic heterogeneities close to the gel transition, dominated by the fast particles. The slow population close to the gel transition shares features with an attraction-driven colloidal glass, including a plateau in the mean squared displacement that provides an estimate for the dynamical localization length. If time permits, I will also discuss the low frequency mechanical properties extracted from the particle pair distance fluctuations."

James Langer: Dynamics and Thermodynamics of the Glass Transition "I will present a summary of the excitation-chain theory of the glass transition, with emphasis on why I think a theoretical framework of this kind is needed in place of mean-field theories, and as a supplement to kinetic constraints and/or jamming pictures. If time permits, I will discuss connections between this theory, spatial heterogeneity in glass-forming systems, and stretched-exponential decay of correlations."

Craig Maloney: Amorphous systems in the athermal, quasistatic limit "Metallic glasses; packings of sand grains, lumps of clay, and many other soft materials all share the same hallmark traits: they deform reversibly (elastically) at low stresses and irreversibly (plastically) at higher stresses, yet lack any underlying crystalline order. In crystalline materials it is generally accepted that the microstructural objects which govern the mechanical behavior are dislocations in the crystal, and most work in the field of crystalline plasticity focuses on describing deformation in terms of them. In the case of amorphous systems, on the other hand, despite decades of work the situation is not so clear. I will present results from extensive computer simulations of simple 2D model amorphous systems subjected to shear in the limit of zero temperature and zero strain rate. In the limit of zero applied strain, the fluctuating piece of the elastic displacement fields will be shown to possess long range correlations which can be rationalized simply in terms of local random forces acting on a homogeneous elastic sheet, and the contribution of these fluctuations to the reduction of the shear modulus in these systems will be discussed. At larger applied strains, plasticity will be shown to occur during discrete cascades of localized, spatially correlated deformation, and a mechanism for this organization will be discussed. These long-range spatial correlations give rise to simple scaling laws which govern the system size dependence of the spectrum of plastic event sizes. Furthermore, we will show that the emergent behavior is insensitive to the precise nature of the underlying interactions, giving support to the notion that plasticity in a broad class of simple amorphous systems can be understood within a unified framework."

Michael Moore: Understanding glasses via spin glasses "A replica formulism will be set up for describing supercooled liquids near their glass transition. The resulting effective potential is equivalent to that for an Ising spin glass in a magnetic field. Results will be taken from simulations of spin glasses to provide an explanation of the main features of glasses."

Douglas Osheroff: The Role of TLS-TLS Interactions In the Dielectric and Accoustic Responses in Glasses "It is now recognized that interactions between tunnelling entities in structural glasses modify the dielectric and accoustic responses of these materials at low temperatures. In addition, these interactions in the presence of a changing electric or strain field result in new dynamical behavior. The speaker will review the state of our knowledge concerning these interactions and their consequences."

Zvi Ovadyahu: Dissipative effects in the electron glass "The out-of-equilibrium transport properties of Anderson insulators exhibit many glassy features. These include slow relaxation, slow approach to a steady state, ageing, and other memory effects that are common characteristics of other types of glasses. However, in contrast with most other glasses, the system dynamics does not slow down upon cooling below a ‘glass-temperature’, a feature consistent with the behavior expected of a quantum glass. The dependence of the dynamics on temperature and carrier concentration suggests the relevance of dissipative effects presumably associated with the coupling of hopping processes to the electronic bath."

Steven Plotkin: Multiple minima problems in biopolymers "I will describe how multiple minima problems arise in heteropolymers, the glassy behavior that emerges, and how these problems are resolved in real proteins. A concept that is central to many theories and applications, from glass physics to protein structure prediction, is that of a meaningful distance metric. I will describe how to systematically generalize the notion of distance to cases where the objects are no longer points, but are higher-dimensional objects such as space curves. Finding the minimal transformation from one space curve to another involves the development of special algorithms utilizing analytic geometry: traditional approaches of integrating partial differential equations will generally not yield a minimal solution, due to the presence of an infinite number of extrema on the effective landscape."

Kenneth Schweizer: Glassy Dynamics and Mechanical Properties of Quiescent and Stressed Particle Suspensions "A predictive microscopic theory for the self-dynamics of glassy hard sphere fluids and colloid/nanoparticle suspensions has been developed which includes activated barrier hopping processes. Calculations of the volume fraction dependent alpha relaxation time, shear viscosity and self-diffusion constant are in good agreement with experiment. Stochastic trajectory solution of the nonlinear Langevin equation of motion allows all single particle time and wavevector dependent correlation functions to be determined. Various measures of dynamic fluctuation effects have been studied including the nongaussian parameter, diffusion-relaxation decoupling and mobility bifurcation, and comparison with experiments, simulations and ideal mode coupling theory have been carried out. External deformation is treated based on the simple idea that stress distorts the confining nonequilibrium free energy which weakens transient localization and accelerates thermally activated viscous flow. Power law and/or exponential dependences of the elastic modulus and yield stress on colloid volume fraction are predicted, and flow curves exhibit an intermediate shear rate dependence of an effective power law form. Most recently the theory has been generalized to treat fluids of nonspherical rigid hard objects. The ideal kinetic glass transition boundary is predicted to be a nonmonotonic function of particle aspect ratio, and is remarkably similar to the jamming behavior of granular materials. The object shape dependence of the entropic barrier and alpha relaxation time have also been studied. Finally, the theoretical approach has been extended and extensively applied to sticky nanoparticle and colloidal suspensions that form polymer-mediated depletion gels. The predicted consequences of a rich interplay between physical bond formation and excluded volume constraints on mechanical properties, transport coefficients and the delayed gel collapse phenomenon have been determined and quantitatively confronted with experiment. This work was done in collaboration with Drs. Erica J. Saltzman, Vladimir Kobelev, Galina Yatsenko and Yeng-Long Chen."

David Weitz: Structure and Properties of Colloidal Glasses "This talk will present recent results exploring the behavior of colloidal glasses, both when there is only a very short range repulsive interaction between the particles, and also when there is a somewhat longer range attractive interaction between the particles. In addition, the behavior of the pariticles under shear will be discussed."

Peter Wolynes: Classical and Quantum Aspects of Structural Glasses "Supercooled liquids and glasses can be viewed as aperiodic crystals. Pursuing this view leads to the random first order transition theory of glasses. A liquid in this picture can be thought of as a mosaic of local energy landscapes. The theory explains quantitatively, without adjustable parameters, the super-Arrhenius slowing of dynamics and emergence of nonexponential relaxation in the supercooled liquid regime. The aging regime of glasses is also quantitatively treated. When quantized, the theory yields a description of the two level systems and Boson peak excitations that dominate the low temperature properties of amorphous solids."

Clare Yu: Dipole Glasses Are Different from Spin Glasses: Absence of a Dipole Glass Transition for Randomly Dilute Classical Ising Dipoles "Dilute dipolar systems in three dimensions are expected to undergo a spin glass transition as the temperature decreases. Contrary to this, we find from Wang-Landau Monte Carlo simulations that at low concentrations x, dipoles randomly placed on a cubic lattice with dipolar interactions do not undergo a phase transition. We find that in the thermodynamic limit the ``glass'' transition temperature T_g goes to zero as 1/sqrt{N} where N is the number of dipoles. The entropy per particle at low temperatures is larger for lower concentrations (x=4.5%) than for higher concentrations (x=20%). Recent specific heat measurements on LiHoYF have confirmed the absence of a transition and the presence of a residual entropy at low temperatures."