Why Russia and China Have Not Formed an Anti-American Alliance

"Why Russia and China Have Not Formed an Anti-American Alliance," Naval War College Review, 56: 4 (Autumn 2003), pp. 39-61

Civil Society and Philanthropy Under Putin

"Civil Society and Philanthropy Under Putin," The International Journal of Not-for-Profit Law 8: 3 (May 2006

The Limits of U.S.-China Military Cooperation: Lessons from 1995-1999

"The Limits of U.S.-China Military Cooperation: Lessons from 1995-1999" (with Kurt Campbell) The Washington Quarterly 29: 1 (Winter 2005), pp. 169-186

Attractive asymmetric inclusions in elastic membranes under tension: cluster phases and membrane invaginations

Up-down asymmetric inclusions impose a local, spontaneous curvature to an elastic membrane. When several of them are inserted in a same membrane, they feel effective forces mediated by the membrane, both of elastic and entropic nature. Following an approach initiated by Dommersnes and Fournier in the vanishing tension case [Eur. Phys. J. B 12, 9 (1999)], and also using a pseudo-analytical micellization theory, we derive the statistical mechanics of asymmetric inclusion assemblies when they are also subject to an additional short-range, attractive interaction. Our main conclusion is that generically, when the membrane is under tension, these inclusions live in small clusters at equilibrium, leading to local membrane invaginations. We also propose a novel curvature-induced demixing mechanism: when inclusions imposing local curvatures of opposite sign coexist, they tend to demix in distinct clusters under realistic conditions. This work has potential implications in the context of the thermodynamics of proteins embedded in biological lipid bilayers

Packing-Limited Growth

We consider growing spheres seeded by random injection in time and space. Growth stops when two spheres meet leading eventually to a jammed state. We study the statistics of growth limited by packing theoretically in d dimensions and via simulation in d=2, 3, and 4. We show how a broad class of such models exhibit distributions of sphere radii with a universal exponent. We construct a scaling theory that relates the fractal structure of these models to the decay of their pore space, a theory that we confirm via numerical simulations. The scaling theory also predicts an upper bound for the universal exponent and is in exact agreement with numerical results for d=4.Comment: 6 pages, 5 figures, 4 tables, revtex4 to appear in Phys. Rev. E, May 200