Publications

Dutch translation, by Gerard de Vries, of a revised version: “Vorm en ethiek: Nabokovs romans en het scholen van de ontvankelijkheid” (“Form and Ethics: Nabokov’s Fiction and the Education of Sensibilities”) De Tweede Ronde (Amsterdam), Winter 1998/99: 191-200. Russian-language version: “Nabokov i etika kamufliazha,” in Vladimir Nabokov: Pro et Contra, ed. B. V. Averin. St. Petersburg: Russian Christian Institute for the Humanities, 2001 II: 377–86.

This article describes briefly several applications of a molecular theory of lipid organization in membranes to systems of biophysical interest. After introducing the basic concepts of this mean field theory we outline three of its recent applications. i) Calculations of lipid chain conformational statistics in membrane bilayers, and comparison of the results (e.g. bond orientational order parameters) to experiment and molecular dynamics simulations. Good agreement is found. ii) A molecular model for lipid-protein interactions, which explicitly considers the effects of a rigid hydrophobic protein on the elastic (conformational) properties of the lipid bilayer. We also analyze the role of the `hydrophobic mismatch' between the protein and lipid bilayer thickness. iii) A molecular level calculation of the vesicle to micelle transition, attendant upon the addition of ('curvature loving') surfactant to a lipid bilayer vesicle. Future applications, e.g. to the calculation of the free energy barriers involved in membrane fusion are briefly mentioned.

For sixty years, from 1260 to 1323, the Mamluk state in Egypt and Syria was at war with the Ilkhanid Mongols based in Persia. This is the first comprehensive study of the political and military aspects of the early years of the war, from the battle of 'Ayn Jalut in 1260 to the battle of Homs in 1281. In between these campaigns, the Mamluk-Ilkhanid struggle was continued in the manner of a 'cold war' with both sides involved in border skirmishes, diplomatic manoeuvres, and espionage. Here, as in the major battles, the Mamluks usually maintained the upper hand, establishing themselves as the foremost Muslim power at the time. By drawing on previously untapped Persian and Arabic sources, the author sheds new light on the confrontation, examining the war within the context of Mongol/Mamluk relations with the Byzantine Empire, the Latin West and the Crusading states.

A two-dimensional lattice model, originally introduced by Granek et al. [J. Chem. Phys. 101, 4331 (l994)], is used to demonstrate the intricate coupling between the intramicellar interactions that determine the optimal aggregation geometry of surfactant molecules in dilute solution, and the intermicellar interactions that govern the phase behavior at higher concentrations. Three very different scenarios of self-assembly and phase evolution are analyzed in detail, based on Monte Carlo studies and theoretical interpretations involving mean-field, Landau-Ginzburg, Bethe-Peierls, and virial expansion schemes. The basic particles in the model are `'unit micelles'' which, due to spontaneous self-assembly or because of excluded area interactions, can fuse td form larger aggregates; These aggregates are envisaged as hat micelles composed of a bilayerlike body surrounded: by a curved semitoroidal rim. The system's Hamiltonian involves one- through four-body potentials between the unit micelles, which account for their tendency to form aggregates of different shapes, e.g., elongated vs disklike micelles. Equivalently the configurational energy of the system is a sum of micellar self-energies involving the packing free energies of the constituent molecules in the bilayer body and in rim segments of different local curvature. The rim energy is a sum of a line tension term and a 1D curvature energy which depends on the rim spontaneous curvature and bending rigidity. Different combinations of these molecular parameters imply different optimal packing geometries and hence different self-assembly and phase behaviors. The emphasis in this paper Is on systems of `'curvature loving'' amphiphiles which, in our model, are characterized by negative line tension. The three systems studied are: (i) A dilute solution of stable disklike micelles which, upon increasing the concentration, undergoes a first-order phase transition to a continuous bilayer with isolated hole defects. An intermediate modulated `'checkerboard'' phase appears under certain conditions at low temperatures. (ii) A system of unit micelles which in dilute solution tend to associate into Linear micelles. These micelles are rodlike gt low temperatures, becoming increasingly more flexible as the temperature increases.-Upon increasing the concentration the micelles grow and undergo (in 2D) a continuous transition into nematic and `'stripe'' phases of long rods. At still higher concentrations the micellar stripes fuse into continuous sheets with line defects. (iii) A system in which, already in dilute solution, the micelles favor the formation of branched aggregates, analogous to the branched cylindrical micelles recently observed in certain surfactant solutions, As the concentration increases the micelles associate into networks (''gels'') composed of a mesh of linear micelles linked by `'T-like'' intermicellar junctions. The network may span the entire system or phase separate and coexist with a dilute micellar phase, depending on the details of the molecular packing parameters. (C) 1995 American Institute of Physics.