Precision Masses of the low-mass binary system GJ 623

We have used Aperture Masking Interferometry and Adaptive Optics (AO) at the Palomar 200'' to obtain precise mass measurements of the binary M dwarf GJ 623. AO observations spread over 3 years combined with a decade of radial velocity measurements constrain all orbital parameters of the GJ 623 binary system accurately enough to critically challenge the models. The dynamical masses measured are m_{1}=0.371\pm0.015 M_{\sun} (4%) and m_{2}=0.115\pm0.0023 M_{\sun} (2%) for the primary and the secondary respectively. Models are not consistent with color and mass, requiring very low metallicities.Comment: 7 pages, 5 figures. Accepted for Ap

PHENIX Highlights

Recent highlights of measurements by the PHENIX experiment at RHIC are presented.Comment: 8 pages, 9 figures. Talk at Quark Matter 200

Readability and test-retest reliability of a psychometric instrument designed to assess HIV/AIDS attitudes, beliefs, behaviours and sources of HIV prevention information of young adults

Objective: This comparative study evaluated the readability and test-retest reliability of a questionnaire designed to assess the attitudes, beliefs behaviours and sources of information about HIV/AIDS among young adults recruited from universities in the United States of America (USA), Turkey and South Africa. Design/Setting: The instrument was administered on two occasions, within a two week interval, to 219 university students in the USA (n = 66), Turkey (n = 53) and South Africa (n = 100). Method: The psychometric instrument developed has five major subscales: demographic, HIV/AIDS attitudes and beliefs, HIV risk sexual behaviour, alcohol and drug use, and HIV sources of information. Results: The instrument’s readability evaluation revealed a Flesch-Kincaid score (literacy difficulty level of the questionnaire) of 8.4, indicating that respondents would need an eighth grade reading level to understand the survey. The overall test-retest reliability coefficients for the items on the demographic subscale were generally high (0.893–0.997). Similarly, high test-retest reliability was obtained for the HIV risk sexual behaviour (0.738–0.996) and the alcohol and drug use (0.562–1.000) subscales. Much lower test-retest reliability was obtained for the HIV/AIDS attitudes and beliefs (0.32–0.80), and sources of information about HIV/AIDS (0.370–0.892) subscales. Conclusion: We found no discernible difference in the reliability data among the respondents from the three countries. The instrument should be of interest to clinicians and researchers investigating the HIV risk behaviours of young adults and older age groups with an eighth grade reading level. The availability of this instrument may enhance HIV population and intervention studies internationally.Web of Scienc

Population genomic, olfactory, dietary, and gut microbiota analyses demonstrate the unique evolutionary trajectory of feral pigs

Domestication is an intriguing evolutionary process. Many domestic populations are subjected to strong human-mediated selection, and when some individuals return to the wild, they are again subjected to selective forces associated with new environments. Generally, these feral populations evolve into something different from their wild predecessors and their members typically possess a combination of both wild and human selected traits. Feralisation can manifest in different forms on a spectrum from a wild to a domestic phenotype. This depends on how the rewilded domesticated populations can readapt to natural environments based on how much potential and flexibility the ancestral genome retains after its domestication signature. Whether feralisation leads to the evolution of new traits that do not exist in the wild or to convergence with wild forms, however, remains unclear. To address this question, we performed population genomic, olfactory, dietary, and gut microbiota analyses on different populations of Sus scrofa (wild boar, hybrid, feral and several domestic pig breeds). Porcine single nucleotide polymorphisms (SNPs) analysis shows that the feral population represents a cluster distinctly separate from all others. Its members display signatures of past artificial selection, as demonstrated by values of FST in specific regions of the genome and bottleneck signature, such as the number and length of runs of homozygosity. Generalised FST values, reacquired olfactory abilities, diet, and gut microbiota variation show current responses to natural selection. Our results suggest that feral pigs are an independent evolutionary unit which can persist so long as levels of human intervention remain unchanged

Operando analysis of a solid oxide fuel cell by environmental transmission electron microscopy

Correlating the microstructure of an energy conversion device to its performance is often a complex exercise, notably in solid oxide fuel cell (SOFC) research. SOFCs combine multiple materials and interfaces that evolve in time due to high operating temperatures and reactive atmospheres. We demonstrate here that operando environmental transmission electron microscopy can simplify the identification of structure-property links in such systems. By contacting a cathode-electrolyte-anode cell to a heating and biasing microelectromechanical system in a single-chamber configuration, a direct correlation is found between the environmental conditions (O2 and H2 partial pressures, temperature), the cell voltage, and the microstructural evolution of the fuel cell, down to the atomic scale. The results shed new insights into the impact of the anode oxidation state and its morphology on the cell electrical properties.Comment: 18 pages, 5 figure

The Potential Energy Landscape and Mechanisms of Diffusion in Liquids

The mechanism of diffusion in supercooled liquids is investigated from the potential energy landscape point of view, with emphasis on the crossover from high- to low-T dynamics. Molecular dynamics simulations with a time dependent mapping to the associated local mininum or inherent structure (IS) are performed on unit-density Lennard-Jones (LJ). New dynamical quantities introduced include r2_{is}(t), the mean-square displacement (MSD) within a basin of attraction of an IS, R2(t), the MSD of the IS itself, and g_{loc}(t) the mean waiting time in a cooperative region. At intermediate T, r2_{is}(t) posesses an interval of linear t-dependence allowing calculation of an intrabasin diffusion constant D_{is}. Near T_{c} diffusion is intrabasin dominated with D = D_{is}. Below T_{c} the local waiting time tau_{loc} exceeds the time, tau_{pl}, needed for the system to explore the basin, indicating the action of barriers. The distinction between motion among the IS below T_{c} and saddle, or border dynamics above T_{c} is discussed.Comment: submitted to pr

Relevance of baseline hard proton-proton spectra for high-energy nucleus-nucleus physics

We discuss three different cases of hard inclusive spectra in proton-proton collisions: high $p_T$ single hadron production at $\sqrt{s}\approx$ 20 GeV and at $\sqrt{s}$ = 62.4 GeV, and direct photon production at $\sqrt{s}$ = 200 GeV; with regard to their relevance for the search of Quark Gluon Plasma signals in A+A collisions at SPS and RHIC energies.Comment: Proceeds. Hot Quarks 2004 Int. Workshop on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions. 26 pages. 26 figs. [minor corrs., refs. added

Multifactorial Patterns of Gene Expression in Colonic Epithelial Cells Predict Disease Phenotypes in Experimental Colitis

Background— The pathogenesis of inflammatory bowel disease (IBD) is complex and the need to identify molecular biomarkers is critical. Epithelial cells play a central role in maintaining intestinal homeostasis. We previously identified five “signature” biomarkers in colonic epithelial cells (CEC) that are predictive of disease phenotype in Crohn\u27s disease. Here we investigate the ability of CEC biomarkers to define the mechanism and severity of intestinal inflammation. Methods— We analyzed the expression of RelA, A20, pIgR, tumor necrosis factor (TNF), and macrophage inflammatory protein (MIP)-2 in CEC of mice with dextran sodium sulfate (DSS) acute colitis or T-cell-mediated chronic colitis. Factor analysis was used to combine the five biomarkers into two multifactorial principal components (PCs). PC scores for individual mice were correlated with disease severity. Results— For both colitis models, PC1 was strongly weighted toward RelA, A20, and pIgR, and PC2 was strongly weighted toward TNF and MIP-2, while the contributions of other biomarkers varied depending on the etiology of inflammation. Disease severity was correlated with elevated PC2 scores in DSS colitis and reduced PC1 scores in T-cell transfer colitis. Downregulation of pIgR was a common feature observed in both colitis models and was associated with altered cellular localization of pIgR and failure to transport IgA. Conclusions— A multifactorial analysis of epithelial gene expression may be more informative than examining single gene responses in IBD. These results provide insight into the homeostatic and proinflammatory functions of CEC in IBD pathogenesis and suggest that biomarker analysis could be useful for evaluating therapeutic options for IBD patients