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During the first days in space, i.e., after a transition from 1G to 0G, more than 50% of the astro- (and cosmonauts) suffer from the Space Adaptation Syndrome (SAS).The symptoms of SAS, like nausea and dizziness, are especially provoked by head movements. Astronauts have mentioned close similarities between the symptoms of SAS and the symptoms they experienced after a 1 hour centrifuge run on Earth, i.e., after a transition from 3G to 1G (denoted by Sickness Induced by Centrifugation, SIC). During several space missions, we related susceptibility to SAS and to SIC in 11 astronauts and found 4 of them being susceptible to both SIC and SAS, and 7 being not susceptible to SIC nor to SAS. This correspondence in susceptibility suggests that SIC and SAS share the same underlying mechanism. To further study this mechanism, several vestibular parameters have been investigated (e.g. postural stability, vestibularly driven eye movements, subjective vertical). We found some striking changes in individual cases that are possibly due to the centrifuge run. However, the variability between subjects generally is very large, making physiological links to SIC and SAS still hard to find.

We have performed the ab initio calculations based on density functional theory to investigate the B3-B1 phase transition and mechanical properties of ZnS. The elastic stiffness coefficients, C11, C12, C44, bulk modulus, Kleinman parameter, Shear modulus, Reuss modulus, Voigt modulus and anisotropy factor are calculated for two polymorphs of ZnS: zincblende (B3) and rocksalt (B1). Our results for the structural parameters and elastic constants at equilibrium phase are in good agreement with the available theoretical and experimental values. Using the enthalpy-pressure data, we have observed the B3 to B1 structural phase transition at 18.5 GPa pressure. In addition to the elastic coefficients under normal conditions, we investigate the pressure dependence of mechanical properties of both phases: up to 65 GPa for B1-phase and 20 GPa for B3-phase. © 2008 Elsevier B.V. All rights reserved.

This paper develops a recursive algorithm for estimating the least-cost transition firing sequences that match the observation of a sequence of labels produced by transition activity in a given labeled Petri net. The Petri nets we consider have transitions that are observable (i.e., their firing produces a not necessarily unique label) or unobservable (i.e., their firing does not produce any label). We assume that each transition in the given net (including unobservable transitions) is associated with a nonnegative cost which captures its likelihood (e.g., the cost could be inversely proportional to the amount of workload or power required to execute the transition). Assuming full knowledge of the structure of a given labeled Petri net, we aim at finding the firing sequence(s) that has (have) the least total cost and is (are) consistent with the observed label sequence. The existence of unobservable transitions in the net makes this task extremely challenging since the number of firing sequences that is consistent with the label observations can potentially be Infinite. Under some conditions on the unobservable transitions of the Petri net, we show that it is possible to use a recursive algorithm that finds the least-cost firing sequence(s) while reconstructing only a finite number of such firing sequences. In particular, if the unobservable transitions in the net are contact-free and have strictly positive costs, this algorithm has storage and computational complexity that is polynomial in the length of the observed sequence of labels. © 2007 IEEE. 4963 4968

Transition metal salt-pluronic liquid crystalline (TMS-PLC) mesophases of A-P85, B-P85 and ((1 - x)A + xB)-P85 (where A is [Cd(H2O) 4](NO3)2, B is [Zn(H2O) 6](NO3)2 and P85 is a triblock copolymer, HO(CH2CH2O)26(CH2(CH 3)CHO)40(CH2CH2O)26H) have been used to produce mesostructured metal sulfide films. The TMS-PLC mesophases of A-P85, B-P85 and (A + B)-P85 are well ordered with a salt/P85 mole ratio between 3.0 and 11.0 with a 3D hexagonal structure. The reaction between the mesophases of A-P85, B-P85 and ((1 - x)A + xB)-P85 and H2S gas at room temperature produces mesostructured CdS, ZnS and Cd1-xZn xS films, respectively. The initial salt concentrations in the TMS-PLC phase determine the final Cd(ii) and Zn(ii) ions in the Cd 1-xZnxS crystal structure, where x can be controlled between 0.0 and 1.0. Fresh samples of the mesophase reacted under an H 2S atmosphere are continues films that slowly leach out excess P85 producing P85 rich dendrite domains and aggregates of 50 to 100 nm particles of mesostructured CdS, ZnS or Cd1-xZnxS. However, well homogenized TMS-PLC mesophases produce stable film samples upon H2S reaction.