Condensation and Evaporation of Mutually Repelling Particles :Steady states and limit cycles

We study condensation and evaporation of particles which repel each other, using a simple set of rules on a square lattice. Different results are obtained for a mobile and an immobile surface layer.A two point limit cycle is observed for high temperature and low pressure in both cases. Here the coverage oscillates between a high and a low value without ever reaching a steady state. The results for the immobile case depend in addition on the initial coverage.Comment: 8 pages, 3 figure

On the role of laser-induced microstructures in influencing the surface energy of magnesia partially stabilized zirconia bioceramic

Surface energy must in some way be connected to surface chemistry and is therefore an important determinant of a biomaterial’s functions. This work elucidates the basic phenomena and wetting mechanisms associated for a widely used bioinert ceramic, magnesia partially stabilized zirconia (MgO-PSZ) following CO2 laser treatment. Contact angles for a set of test liquids were used to measure the wettability characteristics and to reduce the surface energy of the MgO-PSZ before and after CO2 laser treatment. CO2 laser treatment of the MgO-PSZ surface was seen to effect an improvement in the material’s wettability characteristics. Furthermore, it was found that the extent of wettability modi®cation was closely related to the microstructure induced by CO2 laser radiation on the surface of the MgO-PSZ

Improvement and decline of cognitive function in schizophrenia over one year: a longitudinal investigation using latent growth modelling.

BACKGROUND: Long-term follow-up studies of people with schizophrenia report stability of cognitive performance; less is known about any shorter-term changes in cognitive function. METHODS: This longitudinal study aimed to establish whether there was stability, improvement or decline in memory and executive functions over four assessments undertaken prospectively in one year. Cognitive performance was assessed during randomized controlled trials of first- and second-generation antipsychotic medication. Analyses used a latent growth modeling approach, so that individuals who missed some testing occasions could be included and trajectories of cognitive change explored despite missing data. RESULTS: Over the year there was significant decline in spatial recognition but no change in pattern recognition or motor speed. Improvement was seen in planning and spatial working memory tasks; this may reflect improved strategy use with practice. There were significant individual differences in the initial level of performance on all tasks but not in rate of change; the latter may have been due to sample size limitations. Age, sex, premorbid IQ and drug class allocation explained significant variation in level of performance but could not predict change. Patients randomized to first-generation drugs improved more quickly than other groups on the planning task. CONCLUSION: We conclude that cognitive change is present in schizophrenia but the magnitude of change is small when compared with the large differences in cognitive function that exist between patients. Analyses that retain patients who drop out of longitudinal studies, as well as those who complete testing protocols, are important to our understanding of cognition in schizophrenia.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are