Discovery of disc precession in the M31 dipping X-ray binary Bo 158

We present results from three XMM-Newton observations of the M31 low mass X-ray binary XMMU J004314.4+410726.3 (Bo 158), spaced over 3 days in 2004, July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic intensity dips were previously seen to occur on a 2.78-hr period, due to absorption in material that is raised out of the plane of the accretion disc. The report of these observations stated that the dip depth was anti-correlated with source intensity. However, our new observations do not favour a strict intensity dependance, but rather suggest that the dip variation is due to precession of the accretion disc. This is to be expected in LMXBs with a mass ratio <~ 0.3 (period <~ 4 hr), as the disc reaches the 3:1 resonance with the binary companion, causing elongation and precession of the disc. A smoothed particle hydrodynamics simulation of the disc in this system shows retrograde rotation of a disc warp on a period of ~11 P_orb, and prograde disc precession on a period of ~29 P_orb. This is consistent with the observed variation in the depth of the dips. We find that the dipping behaviour is most likely to be modified by the disc precession, hence we predict that the dipping behaviour repeats on a 81+/-3 hr cycle.Comment: 9 pages, 6 figures, accepted for publication by MNRAS, changed conten

Quintessence and Thermal Matter

We investigate the effects of thermal interactions on tracking models of quintessence. We show that even Planck-suppressed interactions between matter and the quintessence field can alter its evolution. The dark energy equation of state is in many cases strongly affected by matter couplings. We obtain a bound on the coupling between quintessence and relativistic relic particles such as the photon or neutrino.Comment: LaTex, 11 pages, 5 figures. Minor additions. Version to appear in Physics Letters

Entropy Production at RHIC

For central heavy ion collisions at the RHIC energy, the entropy per unit rapidity dS/dy at freeze-out is extracted with minimal model dependence from available experimental measurements of particle yields, spectra, and source sizes estimated from two-particle interferometry. The extracted entropy rapidity density is consistent with lattice gauge theory results for a thermalized quark-gluon plasma with an energy density estimated from transverse energy production at RHIC.Comment: 6 pages, 2 figures, Revtex, version to appear in PL

Employing geographical principles for sampling in state of the art dialectological projects

The aims of this paper are twofold: First, we locate the most effective human geographical methods for sampling across space in large-scale dialectological projects. We propose two geographical concepts as a basis for sampling decisions: Geo-demographic classification, which is a multidimensional method used for the socio-economic grouping of areas. We also develop an updated version of functional regions that can be used in sociolinguistic research. We then report on the results of a pilot project that applies these models to collect data regarding the acceptability of vernacular morpho-syntactic forms in the North-East of England. Following the method of natural breaks advocated for dialectology by Horvath and Horvath (2002), we interpret breaks in the probabilistic patterns as areas of dialect transitions. This study contributes to the debate about the role and limitations of spatiality in linguistic analysis. It intends to broaden our knowledge about the interfaces between human geography and dialectology

Nurturing environments and nutrient-rich diets may improve cognitive development: analysis of cognitive trajectories from six to sixty months from the MAL-ED study (OR10-01-19)

Objectives: To identify clusters of cognitive developmental trajectories and associated differentiating factors of children aged 6 to 60 months old in 5 low to middle-income sites.Methods: We followed 835 children and assessed anthropometry at enrolment (≤ 17 d old); bi-weekly illness data (0–24 and 60 mo); non-diarrheal and diarrheal stools (0–24 mo) analyzed for a panel of enteropathogens; quantitative complementary food intakes (9–24 and 60 mo); micronutrient status (Fe, Zn, Vit A; 7, 15, and 24 mo); quality of the child\u27s home environment (6, 24, and 60 mo) and maternal reasoning ability and depressive symptoms via questionnaire. Child cognitive development was assessed by the Bayley Scales of Infant Development III (6, 15 and 24 mo) and Wechsler Preschool and Primary Scale of Intelligence (60 mo). Clusters of trajectories were identified using a latent class mixed model. Differences between clusters were described using discriminant analysis to rank the contribution of each variable using correlation-adjusted t-scores (CAT).Results: Five clusters were identified. From 51 discriminatory factors, 10 had greatest descriptive power: HOME score at 60 mo (mean CAT2 ± SD: 34.6 ± 0.35), proportion of days ill from 0–24 mo (23.9 ± 0.18), years of maternal schooling (13.8 ± 0.23), mean nutrient densities of zinc (12.3 ± 0.07), protein (8.95 ± 0.09), vitamin B6 (8.2 ± 0.10), phytate (7.91 ± 0.05) and mean energy (7.82 ± 0.04) from complementary foods (9–24 mo), % days of exclusive breastfeeding (0–6 mo; 6.42 ± 0.10) and weight-for-age at enrolment (6.14 ± 0.17). The discriminant analysis model fit was statistically significant (Wilk\u27s λ 0.54, P \u3c 0.01).Conclusions: Early life factors associated with higher scoring trajectories included stimulation and support for the child in their home, complementary feeding that typified greater diversity and animal-source foods, and maternal years of schooling. Influences associated with lower scoring trajectories included lower weight at enrolment and higher prevalence of illness. Policies promoting maternal and child nutrition, education and fostering a nurturing environment are likely to have greatest impact on child development

Discovery and modelling of disc precession in the M31 X-ray binary Bo 158?

The low mass X-ray binary (LMXB) associated with the M31 globular cluster Bo 158 is known to exhibit intensity dips on a ~2.78 hr period. This is due to obscuration of the X-ray source on the orbital period by material on the outer edge of the accretion disc. However, the depth of dipping varied from <10% to \~83% in three archival XMM-Newton observations of Bo 158. Previous work suggested that the dip depth was anticorrelated with the X-ray luminosity. However, we present results from three new XMM-Newton observations that suggest that the evolution of dipping is instead due to precession of the accretion disc. Such precession is expected in neutron star LMXBs with mass ratios <0.3 (i.e. with orbital periods <4 hr), such as the Galactic dipping LMXB 4U 1916-053. We simulated the accretion disc of Bo 158 using cutting-edge 3D smoothed particle hydrodynamics (SPH), and using the observed parameters. Our results show disc variability on two time-scales. The disc precesses in a prograde direction on a period of 81+/-3 hr. Also, a radiatively-driven disc warp is present in the inner disc, which undergoes retrograde precesson on a \~31 hr period. From the system geometry, we conclude that the dipping evolution is driven by the disc precession. Hence we predict that the dipping behaviour repeats on a ~81 hr cycle.Comment: 6 pages, 4 figures, to appear in proceedings "The X-ray Universe 2005", San Lorenzo de El Escoriale (Madrid, Spain), 26-30 September 200

Iron Deficiency is Related to Depressive Symptoms in United States Nonpregnant Women of Reproductive Age : A Cross-Sectional Analysis of NHANES 2005-2010

This study was supported by the John L. Beard Program Endowment Fund.Peer reviewedPublisher PD

Interactive computer-based interventions for sexual health promotion (Protocol)

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