Binding energy of localized biexcitons in quantum wells

A variational calculation of the ground state energy of a biexciton in a GaAs/AlGaAs quantum well is presented. The well width fluctuations leading to trapping of the biexcitons are modeled by a parabolic potential. The results obtained for different well widths are compared with recent experimental data. Good agreement is obtained both for the biexciton binding energy and for the Haynes factor. We find that the structure of a biexciton is similar to the one of the H_2 molecule.Comment: 9 pages, 4 figure

Beyond Mean Field Confrontation of Different Models with High Transverse Momentum Proton Spectra

Several models have been proposed to simulate heavy ion reactions beyond the mean field level. The lack of data in phase space regions which may be sensitive to different treatments of fluctuations made it difficult to judge these approaches. The recently published high energy proton spectra, measured in the reaction 94 AMeV Ar + Ta, allow for the first time for a comparison of the models with data. We find that these spectra are reproduced by Quantum Molecular Dynamics (QMD) and Boltzmann Uehling Uhlenbeck (BUU) calculations. Models like Boltzmann Langevin (BL) in which additional fluctuations in momentum space are introduced overpredict the proton yield at very high energies. The BL approach has been successfully used to describe the recently measured very subthreshold kaon production assuming that the fluctuations provide the necessary energy to overcome the threshold in two body collisions. Our new findings suggest that the very subthreshold kaon production cannot be due to two body scattering and thus remains a open problem.Comment: 5 pages, 3 figures (eps), revte

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Individual repeatability and heritability of divorce in a wild population

Funding All authors were supported by a European Research Council grant to JMR. Fieldwork was supported by the Natural Sciences and Engineering Research Council of Canada and the University of British Columbia. Acknowledgments We thank the Tsawout and Tseycum First Nation bands for access to Mandarte, Peter Arcese, Lukas Keller, Pirmin Nietlisbach, and the University of Aberdeen Maxwell High Performance Computing cluster.Peer reviewedPostprin

Quantifying inbreeding avoidance through extra-pair reproduction

© 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.Peer reviewedPublisher PD

Effects of PDE4 inhibitors on lipopolysaccharide-induced priming of superoxide anion production from human mononuclear cells.

AIMS: Phosphodiesterase 4 (PDE4) inhibitors have been described as potent anti-inflammatory compounds, involving an increase in intracellular levels of cyclic 3',5'-adenosine monophosphate (AMP). The aim of this study was to compare the effects of selective PDE4 inhibitors, rolipram and RP 73-401 with the cell permeable analogue of cyclic AMP, dibutyryl-cyclic AMP (db-cAMP) and the anti-inflammatory cytokine interleukin-10 (IL-10) on superoxide anion production from peripheral blood mononuclear cells preincubated with lipopolysaccharide (LPS). MAJOR FINDINGS: We report that, after incubation of the cells with LPS, a large increase in superoxide anion production was observed. Rolipram or RP 73-401 (10(-8) to 10(-5) M) induced significant reductions of fMLP-induced superoxide anion production in cells incubated with or without LPS. The db-cAMP (10(-5) to 10(-3) M) also elicited dose-dependent inhibitions of the fMLP-induced superoxide anion production. In contrast, IL-10 (1 or 10 ng/ml) did not elicit a reduction in fMLP-induced superoxide anion production in both conditions. PRINCIPAL CONCLUSION: These results suggest that the inhibitory activity of PDE4 inhibitors on fMLP-induced production of superoxide anion production is mediated by db-cAMP rather than IL-10