Phase Separation of Rigid-Rod Suspensions in Shear Flow

We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

How do types of employment relate to health indicators? Findings from the Second European Survey on Working Conditions

http://deepblue.lib.umich.edu/bitstream/2027.42/56182/1/Benavides FG, How do types of employment relate to health indicators - Findings from the Second European Survey on Working Conditions, 2000.pd

First gut contents in a Cretaceous sea turtle

Modern sea turtles utilize a variety of feeding strategies ranging from herbivory to omnivory. In contrast, the diets of fossil sea turtles are poorly known. This study reports the first direct evidence: inoceramid bivalve shell pieces (encased in phosphatic material) preserved within the body cavities of several small protostegid turtles (cf. Notochelone) from the Lower Cretaceous of Australia. The shell fragments are densely packed and approximately 5–20 mm across. Identical shell accumulations have been found within coprolite masses from the same deposits; these are of a correct size to have originated from Notochelone, and indicate that benthic molluscs were regular food items. The thin, flexible inoceramid shells (composed of organic material integrated into a prismatic calcite framework) appear to have been bitten into segments and ingested, presumably in conjunction with visceral/mantle tissues and encrusting organisms. Although protostegids have been elsewhere interpreted as potential molluscivores, their primitive limb morphology is thought to have limited them to surface feeding. However, the evidence here that at least some forms were able to utilize benthic invertebrate prey indicates that, like modern sea turtles, protostegids probably exhibited a much broader range of feeding habits

Heterogeneous nucleation and microstructure formation in colloidal model systems with various interactions

Recent studies of crystal nucleation and further microstructure formation in colloidal model systems are reviewed. Homogeneous as well as different heterogeneous nucleation scenarios will be discussed. We focus on the crystallization process of one component colloidal model systems with hard sphere like interaction, long range electrostatic interaction and depletion force induced attractive interaction. Heterogeneous crystallization on flat and smooth substrates, on structured substrates, induced by different kind of seed particles as well as inoculation adding a larger amount of seeds will be presented