Chiral and herringbone symmetry breaking in water-surface monolayers

We report the observation from monolayers of eicosanoic acid in the L′2 phase of three distinct out-of-plane first-order diffraction peaks, indicating molecular tilt in a nonsymmetry direction and hence the absence of mirror symmetry. At lower pressures the molecules tilt in the direction of their nearest neighbors. In this region we find a structural transition, which we tentatively identify as the rotator-herringbone transition L2d−L2h

Falls in the general elderly population: a 3- and 6- year prospective study of risk factors using data from the longitudinal population study 'Good ageing in Skane'.

Accidental falls in the elderly are a major health problem, despite extensive research on risk factors and prevention. Only a limited number of multifactorial, long-term prospective studies have been performed on risk factors for falls in the general elderly population. The aim of this study was to identify risk factors predicting falls in a general elderly population after three and six years, using a prospective design

Stabilization of tilt order by chain flexibility in Langmuir monolayers

Langmuir monolayers are modeled as systems of short chains, which are confined to a planar surface at one end, but free to move within the plane. The phase behavior is calculated in a mean field approximation, which combines the self consistent field method with elements of classical density functional theory. It is shown that phases with tilt order are unstable in systems of stiff chains, but can be stabilized by chain conformational entropy in systems of sufficiently flexible chains. The chain entropy is also responsible for the appearance of an additional untilted phase, the liquid expanded phase. The region of stability of the different phases is discussed, and their microscopic structure is analyzed in some detail.Comment: to appear in Phys. Rev.