The primordial Helium-4 abundance determination: systematic effects

By extrapolating to O/H = N/H = 0 the empirical correlations Y-O/H and Y-N/H defined by a relatively large sample of ~ 45 Blue Compact Dwarfs (BCDs), we have obtained a primordial 4Helium mass fraction Yp= 0.2443+/-0.0015 with dY/dZ = 2.4+/-1.0. This result is in excellent agreement with the average Yp= 0.2452+/-0.0015 determined in the two most metal-deficient BCDs known, I Zw 18 (Zsun/50) and SBS 0335-052 (Zsun/41), where the correction for He production is smallest. The quoted error (1sigma) of < 1% is statistical and does not include systematic effects. We examine various systematic effects including collisional excitation of Hydrogen lines, ionization structure and temperature fluctuation effects, and underlying stellar HeI absorption, and conclude that combining all systematic effects, our Yp may be underestimated by ~ 2-4%. Taken at face value, our Yp implies a baryon-to-photon number ratio eta = 4.7x10^-10 and a baryon mass fraction Omega_b h^2_{100} = 0.017+/-0.005 (2sigma), consistent with the values obtained from deuterium and Cosmic Microwave Background measurements. Correcting Yp upward by 2-4% would make the agreement even better.Comment: 12 pages, 5 PS figures, to appear in "Matter in the Universe", ed P. Jetzer, K. Pretzl and R. von Steiger, Kluwer, Dordrecht (2002

Strength of Hydrogen Bond Network Takes Crucial Roles in the Dissociation Process of Inhibitors from the HIV-1 Protease Binding Pocket

To understand the underlying mechanisms of significant differences in dissociation rate constant among different inhibitors for HIV-1 protease, we performed steered molecular dynamics (SMD) simulations to analyze the entire dissociation processes of inhibitors from the binding pocket of protease at atomistic details. We found that the strength of hydrogen bond network between inhibitor and the protease takes crucial roles in the dissociation process. We showed that the hydrogen bond network in the cyclic urea inhibitors AHA001/XK263 is less stable than that of the approved inhibitor ABT538 because of their large differences in the structures of the networks. In the cyclic urea inhibitor bound complex, the hydrogen bonds often distribute at the flap tips and the active site. In contrast, there are additional accessorial hydrogen bonds formed at the lateral sides of the flaps and the active site in the ABT538 bound complex, which take crucial roles in stabilizing the hydrogen bond network. In addition, the water molecule W301 also plays important roles in stabilizing the hydrogen bond network through its flexible movement by acting as a collision buffer and helping the rebinding of hydrogen bonds at the flap tips. Because of its high stability, the hydrogen bond network of ABT538 complex can work together with the hydrophobic clusters to resist the dissociation, resulting in much lower dissociation rate constant than those of cyclic urea inhibitor complexes. This study may provide useful guidelines for design of novel potent inhibitors with optimized interactions

A probability-conserving cross-section biasing mechanism for variance reduction in Monte Carlo particle transport calculations

In Monte Carlo particle transport codes, it is often important to adjust reaction cross sections to reduce the variance of calculations of relatively rare events, in a technique known as non-analogous Monte Carlo. We present the theory and sample code for a Geant4 process which allows the cross section of a G4VDiscreteProcess to be scaled, while adjusting track weights so as to mitigate the effects of altered primary beam depletion induced by the cross section change. This makes it possible to increase the cross section of nuclear reactions by factors exceeding 10^4 (in appropriate cases), without distorting the results of energy deposition calculations or coincidence rates. The procedure is also valid for bias factors less than unity, which is useful, for example, in problems that involve computation of particle penetration deep into a target, such as occurs in atmospheric showers or in shielding

Baseline Religion Involvement Predicts Subsequent Salivary Cortisol Levels Among Male But not Female Black Youth

Background: Compared to Whites, Blacks are exposed to higher levels of chronic stress in the United States. As a result, major Black-White differences exist in the baseline and response of cortisol. Yet, the potential association between baseline religiosity and subsequent cortisol levels of Blacks are not known. Objectives: In the current study we aimed to determine the association between baseline religious behaviors and daytime salivary cortisol level among male and female Black youth. Materials and Methods: With a longitudinal design, data came from wave 1 (1994) and wave 6 (2000) of a cohort from an urban area in the Midwest of the United States. The study followed 227 Black adolescents (109 males and 118 females) for six years. Socio-demographics and religious behaviors (frequency of participation in religious activities) were measured at baseline. Base morning cortisol level at wave 6 was the outcome. We fitted a linear regression model to test the association between baseline religiosity at wave 1 and cortisol level at wave 6, while baseline age, socio-economics, and psychological symptoms were controlled. Results: In the pooled sample, frequency of participation in religious activities at baseline was negatively associated with mean cortisol level at follow up (r = -0.29, P > 0.01) among all, males (r = -0.38, P > 0.01), but not females (r = -.20, P > 0.05). Frequency of participation in religious activities remained a significant predictor of subsequent cortisol level (b = -0.283, 95% CI = -.107 - -0.022) while the effect of age, socioeconomics, and psychological symptoms were controlled. We could only find such an association among male Black youth (b = -0.368, 95% CI = -0.148 - -0.024) but not female Black youth (b = -0.229, 95% CI = -.113 - 0.011). Conclusions: Religiosity has been used as a coping mechanism among Blacks. Religiosity may also be related to stress regulation among Black youth. Future studies need to test complex associations between race, sex, religiosity, chronic stress, coping, and function of hypothalamo-pituitary-adrenal (HPA). It is not known whether male Black youth who are and those who are not religious differently cope with stress associated with daily discrimination and living in disadvantaged neighborhoods

Measuring the health of the Indian elderly: evidence from National Sample Survey data

<p>Abstract</p> <p>Background</p> <p>Comparable health measures across different sets of populations are essential for describing the distribution of health outcomes and assessing the impact of interventions on these outcomes. Self-reported health (SRH) is a commonly used indicator of health in household surveys and has been shown to be predictive of future mortality. However, the susceptibility of SRH to influence by individuals' expectations complicates its interpretation and undermines its usefulness.</p> <p>Methods</p> <p>This paper applies the empirical methodology of Lindeboom and van Doorslaer (2004) to investigate elderly health in India using data from the 52^ndround of the National Sample Survey conducted in 1995-96 that includes both an SRH variable as well as a range of objective indicators of disability and ill health. The empirical testing was conducted on stratified homogeneous groups, based on four factors: gender, education, rural-urban residence, and region.</p> <p>Results</p> <p>We find that region generally has a significant impact on how women perceive their health. Reporting heterogeneity can arise not only from cut-point shifts, but also from differences in health effects by objective health measures. In contrast, we find little evidence of reporting heterogeneity due to differences in gender or educational status within regions. Rural-urban residence does matter in some cases. The findings are robust with different specifications of objective health indicators.</p> <p>Conclusions</p> <p>Our exercise supports the thesis that the region of residence is associated with different cut-points and reporting behavior on health surveys. We believe this is the first paper that applies the Lindeboom-van Doorslaer methodology to data on the elderly in a developing country, showing the feasibility of applying this methodology to data from many existing cross-sectional health surveys.</p

Does Selective Migration Explain the Hispanic Paradox?: A Comparative Analysis of Mexicans in the U.S. and Mexico

Latino immigrants, particularly Mexican, have some health advantages over U.S.-born Mexicans and Whites. Because of their lower socioeconomic status, this phenomenon has been called the epidemiologic “Hispanic Paradox.” While cultural theories have dominated explanations for the Paradox, the role of selective migration has been inadequately addressed. This study is among the few to combine Mexican and U.S. data to examine health selectivity in activity limitation, self-rated health, and chronic conditions among Mexican immigrants, ages 18 and over. Drawing on theories of selective migration, this study tested the “healthy migrant” and “salmon-bias” hypotheses by comparing the health of Mexican immigrants in the U.S. to non-migrants in Mexico, and to return migrants in Mexico. Results suggest that there are both healthy migrant and salmon-bias effects in activity limitation, but not other health aspects. In fact, consistent with prior research, immigrants are negatively selected on self-rated health. Future research should consider the complexities of migrants’ health profiles and examine selection mechanisms alongside other factors such as acculturation

Disability and the Immigrant Health Paradox: Gender and Timing of Migration

Although research has documented better health and longer life expectancy among the foreign-born relative to their U.S.-born counterparts, the U.S. Mexican-origin immigrant population is diverse and the healthy immigrant effect likely varies by key structural and demographic factors such as gender, migration history, and duration in the United States. Using a life course framework, we use data from the Hispanic Established Populations for the Epidemiologic Study of the Elderly (H-EPESE 1993–2013) which includes Mexican-American individuals aged 65 and older to assess the heterogeneity in the immigrant health advantage by age of migration and gender. We find that age of migration is an important delineating factor for disability among both men and women. The healthy immigrant hypothesis is only observable among mid- and late-life migrant men for ADL disability. While among immigrant women, late-life migrants are more likely to have an IADL disability putting them at a health disadvantage. These findings illustrate that Mexican immigrants are not a homogeneous group and migrant health selectivity depends on both gender and when migrants arrived in the United States

Blinded predictions of distribution coefficients in the SAMPL5 challenge

In the context of the SAMPL5 challenge water-cyclohexane distribution coefficients for 53 drug-like molecules were predicted. Four different models based on molecular dynamics free energy calculations were tested. All models initially assumed only one chemical state present in aqueous or organic phases. Model A is based on results from an alchemical annihilation scheme; model B adds a long range correction for the Lennard Jones potentials to model A; model C adds charging free energy corrections; model D applies the charging correction from model C to ionizable species only. Model A and B perform better in terms of mean-unsigned error ([Formula: see text] D units − 95 % confidence interval) and determination coefficient [Formula: see text] , while charging corrections lead to poorer results with model D ([Formula: see text] and [Formula: see text] ). Because overall errors were large, a retrospective analysis that allowed co-existence of ionisable and neutral species of a molecule in aqueous phase was investigated. This considerably reduced systematic errors ([Formula: see text] and [Formula: see text] ). Overall accurate [Formula: see text] predictions for drug-like molecules that may adopt multiple tautomers and charge states proved difficult, indicating a need for methodological advances to enable satisfactory treatment by explicit-solvent molecular simulations. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10822-016-9969-1) contains supplementary material, which is available to authorized users

Psychoneuroimmunology: application to ocular diseases

Psychoneuroimmunology (PNI) is a relatively new discipline within the field of neuroscience which researches the relationship between emotional states, the central and peripheral nervous systems, and the endocrine and immune systems. Negative psychological states, such as stress, anxiety, and depression, may alter immune system regulation and modulation of peripheral cytokines. A plethora of PNI studies have shown that increased psychological stress and depression are associated with an alteration of immune functioning and worsened health outcomes for many conditions. To date, application of PNI methodology has not been reported for ocular diseases. This article provides an historical perspective on the origins of the rift between the emotional and spiritual from physical aspects of disease. A review of how stress is mediated through sympathetic adrenomedullary and hypothalamic pituitary axis activation with shifts in immunity is provided. The literature which supports spirituality in healing is presented. Finally, ocular diseases which would be most amenable to a PNI approach are discussed

Genetic dissection of fruit quality traits in the octoploid cultivated strawberry highlights the role of homoeo-QTL in their control

Fruit quality traits are major breeding targets in the Rosaceae. Several of the major Rosaceae species are current or ancient polyploids. To dissect the inheritance of fruit quality traits in polyploid fleshy fruit species, we used a cultivated strawberry segregating population comprising a 213 full-sibling F1 progeny from a cross between the variety ‘Capitola’ and the genotype ‘CF1116’. We previously developed the most comprehensive strawberry linkage map, which displays seven homoeology groups (HG), including each four homoeology linkage groups (Genetics 179:2045–2060, 2008). The map was used to identify quantitative trait loci (QTL) for 19 fruit traits related to fruit development, texture, colour, anthocyanin, sugar and organic acid contents. Analyses were carried out over two or three successive years on field-grown plants. QTL were detected for all the analysed traits. Because strawberry is an octopolyploid species, QTL controlling a given trait and located at orthologous positions on different homoeologous linkage groups within one HG are considered as homoeo-QTL. We found that, for various traits, about one-fourth of QTL were putative homoeo-QTL and were localised on two linkage groups. Several homoeo-QTL could be detected the same year, suggesting that several copies of the gene underlying the QTL are functional. The detection of some other homoeo-QTL was year-dependent. Therefore, changes in allelic expression could take place in response to environmental changes. We believe that, in strawberry as in other polyploid fruit species, the mechanisms unravelled in the present study may play a crucial role in the variations of fruit quality