Learn More
An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain--for example as required by packings composed of deformable but(More)
A few years ago a " jamming diagram " has been proposed as a nonequilibrium phase diagram to describe the physics of glass transitions and granular materials in a unified way. Granular systems " jam " , i.e. develop a yield stress, when their packing fraction reaches a certain critical value upon compression. At zero temperature and load, this transition(More)
Selective binding of multivalent ligands within a mixture of polyvalent amphiphiles provides, in principle, a simple mechanism for driving domain formation in self-assemblies. Divalent cations are shown here to crossbridge polyanionic amphiphiles, which thereby demix from neutral amphiphiles and form spots or rafts within vesicles as well as stripes within(More)
An ensemble approach for force networks in static granular packings is developed. The framework is based on the separation of packing and force scales, together with an a priori flat measure in the force phase space under the constraints that the contact forces are repulsive and balance on every particle. In this paper we will give a general formulation of(More)
Polyphosphoinositides are among the most highly charged molecules in the cell membrane, and the most common polyphosphoinositide, phosphatidylinositol-4,5-bisphosphate (PIP(2)), is involved in many mechanical and biochemical processes in the cell membrane. Divalent cations such as calcium can cause clustering of the polyanionic PIP(2), but the origin and(More)
We study the origin of the scaling behavior in frictionless granular media above the jamming transition by analyzing their linear response. The response to local forcing is non-self-averaging and fluctuates over a length scale that diverges at the jamming transition. The response to global forcing becomes increasingly nonaffine near the jamming transition.(More)
The effects of particle shape on the vibrational properties of colloidal glasses are studied experimentally. "Ellipsoidal glasses" are created by stretching polystyrene spheres to different aspect ratios and then suspending the resulting ellipsoidal particles in water at a high packing fraction. By measuring displacement correlations between particles, we(More)
We numerically study the distribution P(f) of contact forces in frictionless bead packs, by averaging over the ensemble of all possible force network configurations. We resort to umbrella sampling to resolve the asymptotic decay of P(f) for large f , and determine P(f) down to values of order 10{-45} for ordered and disordered systems in two (2D) and three(More)
A scenario for the yielding of granular matter is presented by considering the ensemble of force networks for a given contact network and applied shear stress tau. As tau is increased, the probability distribution of contact forces becomes highly anisotropic, the difference between average contact forces along minor and major axes grows, and the allowed(More)
By calculating the linear response of packings of soft frictionless disks to quasistatic external perturbations, we investigate the critical scaling behavior of their elastic properties and nonaffine deformations as a function of the distance to jamming. Averaged over an ensemble of similar packings, these systems are well described by elasticity, while in(More)