Rhythmogenic neuronal networks, pacemakers, and k-cores (2008)
Schwab, David J., Bruinsma, Robijn F., Levine, Alex J.
Neuronal networks are controlled by a combination of the dynamics of individual neurons and the connectivity of the network that links them together. We study a minimal model of the preBotzinger...
Effective Viscosity of a Dilute Suspension of Membrane-bound Inclusions (2008)
Henle, Mark L., Levine, Alex J.
When particulate suspensions are sheared, perturbations in the shear flows around the rigid particles increase the local energy dissipation, so that the viscosity of the suspension is effectively...
Corrections to the Saffman-Delbruck mobility for membrane bound proteins (2007)
Naji, Ali, Levine, Alex J., Pincus, Philip A.
Recent experiments by Y. Gambin et al. [PNAS 103, 2098 (2006)] have called into question the applicability of the Saffman-Delbruck diffusivity for proteins embedded in the lipid bilayers. We present...
Hydrodynamic Screening And Nonequilibrium Phase Transitions In Stokesian Fluidised Beds (2007)
Alex J Levine, Sriram Ramaswamy, Erwin Frey, Robijn Bruinsma
this paper we calculate the statistical properties of velocity and concentration fluctuations in steady-state sedimentation ignoring fluid inertia, using the method
Buckling and force propagation along intracellular microtubules (2007)
Das, Moumita, Levine, Alex J., MacKintosh, F. C.
Motivated by recent experiments showing the buckling of microtubules in cells, we study theoretically the mechanical response of, and force propagation along elastic filaments embedded in a...
The effect of curvature and topology on membrane hydrodynamics (2007)
Henle, Mark L., McGorty, R., Dinsmore, A. D., Levine, Alex J.
We study the mobility of extended objects (rods) on a spherical liquid-liquid interface to show how this quantity is modified in a striking manner by both the curvature and the topology of the...
Non-equilibrium mechanics and dynamics of motor activated gels (2007)
MacKintosh, Fred C., Levine, Alex J.
The mechanics of cells is strongly affected by molecular motors that generate forces in the cellular cytoskeleton. We develop a model for cytoskeletal networks driven out of equilibrium by molecular...
Rheology and Contact Lifetime Distribution in Dense Granular Flows (2007)
Silbert, Leonardo E., Grest, Gary S., Brewster, Robert, Levine, Alex J.
We study the rheology and distribution of interparticle contact lifetimes for gravity-driven, dense granular flows of non-cohesive particles down an inclined plane using large-scale, three...
Intermolecular Adhesion in Conjugated Polymers (2006)
Schmit, Jeremy D., Levine, Alex J.
Conjugated polymers are observed to aggregate in solution. To account for this observation we propose a inter-chain binding mechanism based on the intermolecular tunneling of the delocalized...
Capillary wave dynamics on supported viscoelastic films: Single and double layers (2006)
Henle, Mark L., Levine, Alex J.
We study the capillary wave dynamics of a single viscoelastic supported film and of a double layer of immiscible viscoelastic supported films. Using both simple scaling arguments and a continuum...
Filamin cross-linked semiflexible networks: Fragility under strain (2006)
DiDonna, B. A., Levine, Alex J.
The semiflexible F-actin network of the cytoskeleton is cross-linked by a variety of proteins including filamin, which contain Ig-domains that unfold under applied tension. We examine a simple...
Unfolding cross-linkers as rheology regulators in F-actin networks (2005)
DiDonna, B. A., Levine, Alex J.
We report on the nonlinear mechanical properties of a statistically homogeneous, isotropic semiflexible network cross-linked by polymers containing numerous small unfolding domains, such as the...
Plug flow and the breakdown of Bagnold scaling in cohesive granular flows (2005)
Brewster, Robert, Grest, Gary S., Landry, James W., Levine, Alex J.
Cohesive granular media flowing down an inclined plane are studied by discrete element simulations. Previous work on cohesionless granular media demonstrated that within the steady flow regime where...
The nonlinear elasticity of an $\alpha$-helical polypeptide: Monte Carlo studies (2004)
Chakrabarti, Buddhapriya, Levine, Alex J.
We perform Monte Carlo simulations to study the elastic properties of the helix-coil worm-like chain model of alpha-helical polypeptides. In this model the secondary structure enters as a scalar...
The nonlinear elasticity of an $\alpha$-helical polypeptide (2004)
Chakrabarti, Buddhapriya, Levine, Alex J.
We study a minimal extension of the worm-like chain to describe polypeptides having alpha-helical secondary structure. In this model presence/absence of secondary structure enters as a scalar...
Intermolecular adhesion in conducting polymers (2004)
Schmit, Jeremy D., Levine, Alex J.
We analyze the interaction of two conducting, charged polymer chains in solution using a minimal model for their electronic degrees of freedom. We show that a crossing of the two chains in which the...
The helix--coil transition on the worm--like chain (2004)
I propose a variation of the standard worm--like chain model to account for internal order parameter (helix/coil) fields on the polymer chain. This internal order parameter field influences polymer...
Dynamics of rigid and flexible extended bodies in viscous films and membranes (2003)
Levine, Alex J., Liverpool, T. B., MacKintosh, F. C.
We study the dynamics of extended rod-like bodies in (or associated with) membranes and films. We demonstrate a striking difference between the mobilities in films and bulk fluids, even when the...
On the mobility of extended bodies in viscous films and membranes (2003)
Levine, Alex J., Liverpool, T. B., MacKintosh, F. C.
We develop general methods to calculate the mobilities of extended bodies in (or associated with) membranes and films. We demonstrate a striking difference between in-plane motion of rod-like...
Stability of Monomer-Dimer Piles (2001)
Ertas, Deniz, Halsey, Thomas C., Levine, Alex J., Mason, Thomas G.
We measure how strong, localized contact adhesion between grains affects the maximum static critical angle, theta_c, of a dry sand pile. By mixing dimer grains, each consisting of two spheres that...
Shear-induced Diffusion in Dilute Suspensions of Charged Colloids (2001)
Breedveld, Victor, Levine, Alex J.
We propose a model for the nonequilibrium enhancement of colloidal self-diffusion in an externally imposed shear flow in charged systems. The enhancement of diffusion is calculated in terms of the...
Dynamics of viscoelastic membranes (2001)
Levine, Alex J., MacKintosh, F. C.
We determine both the in-plane and out-of-plane dynamics of viscoelastic membranes separating two viscous fluids in order to understand microrheological studies of such membranes. We demonstrate the...
Two-point microrheology and the electrostatic analogy (2001)
Levine, Alex J., Lubensky, T. C.
The recent experiments of Crocker et al. suggest that microrheological measurements obtained from the correlated fluctuations of widely-separatedprobe particles determine the rheological properties...
The response function of a sphere in a viscoelastic two-fluid medium (2000)
Levine, Alex J., Lubensky, T. C.
In order to address basic questions of importance to microrheology, we study the dynamics of a rigid sphere embedded in a model viscoelastic medium consisting of an elastic network permeated by a...
One- and two-particle microrheology (2000)
Levine, Alex J., Lubensky, T. C.
We study the dynamics of rigid spheres embedded in viscoelastic media and address two questions of importance to microrheology. First we calculate the complete response to an external force of a...
Boundary Effects in Chiral Polymer Hexatics (1999)
Kamien, Randall D., Levine, Alex J.
Boundary effects in liquid-crystalline phases can be large due to long-ranged orientational correlations. We show that the chiral hexatic phase can be locked into an apparent three-dimensional N+6...
Impurity mediated nucleation in hexadecane-in-water emulsions (1998)
Herhold, Amy, Ertas, Deniz, Levine, Alex J., King Jr, H. E.
We report detailed nucleation studies on the liquid-to-solid transition of hexadecane using nearly monodisperse hexadecane-in-water emulsions. A careful consideration of the kinetics of isothermal...
Halsey, Thomas C., Levine, Alex J.
Capillary forces significantly affect the stability of sandpiles. We analyze the stability of sandpiles with such forces, and find that the critical angle is unchanged in the limit of an infinitely...
Capillary-Wave and Chain-Length Effects at Polymer/Polymer Interfaces (1997)
Lacasse, Martin-D., Grest, Gary S., Levine, Alex J.
A continuum-space bead-spring model is used to study the phase behavior of binary blends of homopolymers and the structure of the interface between the two immiscible phases. The structure of the...
Corrections to the Saffman-Delbrück Mobility for Membrane Bound Proteins
Naji, Ali, Levine, Alex J., Pincus, P. A.
Recent experiments (Gambin, Y., R. Lopez-Esparza, M. Reffay, E. Sierecki, N. S. Gov, M. Genest, R. S. Hodes, and W. Urbach. 2006. Proc. Natl. Acad. Sci. USA. 103:2098–2102) have called into...