XMM-Newton observations of the complex spin pulse of the intermediate polar PQ~Geminorum

The intermediate polar PQ Geminorum shows a complex pulsation, caused by a spinning white dwarf, which varies markedly with wavelength. We report XMM-Newton observations, including the soft and hard X-ray bands and the first UV lightcurves of this star. We update the ephemeris for PQ Gem allowing us to align these data with a compilation of lightcurves from the optical to the X-ray. Building on work by previous authors, we show how a model in which accretion flows along skewed field lines, viewed at the correct inclination, can explain the major features of the lightcurves in all bands. We discuss how the skew of the field lines relates to the spinning down of the white-dwarf rotation.Comment: 7 pages, 7 figures, accepted for publication in MNRA

Sexual behaviour of men and women within age-disparate partnerships in South Africa: implications for young women's HIV risk

BACKGROUND: Age-disparate partnerships are hypothesized to increase HIV-risk for young women. However, the evidence base remains mixed. Most studies have focused only on unprotected sex among women in the partnership. Consequently, little is known about other risky behaviours, such as transactional sex, alcohol use, and concurrency, as well as the behaviours of the men who partner with young women. We therefore examined differences in various sexual behaviours of both young women and their male partners by partnership age difference. METHODS: We used nationally representative data from South Africa (2012) on partnerships reported by 16-24 year old black African women (n = 818) and by black African men in partnerships with 16-24 year old women (n = 985). We compared sexual behaviours in age-disparate partnerships and age-similar partnerships, using multiple logistic regression to control for potential confounders and to assess rural/urban differences. RESULTS: Young women in age-disparate partnerships were more likely to report unprotected sex than young women in similar-aged partnerships (aOR:1.51; p = 0.014; 95%CI:1.09-2.11). Men in partnerships with young women were more likely to report unprotected sex (aOR:1.92; p<0.01; 95%CI:1.31-2.81), transactional sex (aOR:2.73; p<0.01; 95%CI:1.64-4.56), drinking alcohol before sex (aOR:1.60; p = 0.062; 95%CI:0.98-2.61), and concurrency (aOR:1.39; p = 0.097; 95%CI:0.94-2.07) when their partners were five or more years younger. The association between age-disparate partnerships and transactional sex (aOR:4.14; p<0.01; 95%CI: 2.03-8.46) and alcohol use (aOR:2.24; p<0.013; 95%CI:1.20-4.19) was only found in urban areas. CONCLUSIONS: Results provide evidence that young women's age-disparate partnerships involve greater sexual risk, particularly through the risky behaviours of their male partners, with the risk amplified for young women in urban areas

Developing an integrated concept for the E-ELT Multi-Object Spectrograph (MOSAIC): design issues and trade-offs

We present a discussion of the design issues and trade-offs that have been considered in putting together a new concept for MOSAIC, the multi-object spectrograph for the E-ELT. MOSAIC aims to address the combined science cases for E-ELT MOS that arose from the earlier studies of the multi-object and multi-adaptive optics instruments. MOSAIC combines the advantages of a highly-multiplexed instrument targeting single-point objects with one which has a more modest multiplex but can spatially resolve a source with high resolution (IFU). These will span across two wavebands: visible and near-infrared

Fine Particulates, Preterm Birth, and Membrane Rupture in Rochester, NY

Background: It remains unclear whether fine particulate (PM2.5) exposure affects risk of preterm birth and prelabor rupture of membranes. Unmeasured, poorly measured, and undiscovered individual-level confounders might have introduced bias into past studies that relied on between-women comparisons. Methods: This was a longitudinal study of preterm birth and prelabor rupture of membranes in Rochester, NY, 2004–2012 (N = 3,264 women, N = 7,121 singleton births). We used conditional logistic regression to match pregnancies to the same woman and estimate the odds of each outcome associated with average PM2.5 concentrations during each trimester and whole pregnancy. Results: For preterm birth, adjusted odds ratios (95% confidence interval) for 1 µg/m3 increase in PM2.5 in the first trimester, second trimester, third trimester, and whole pregnancy were 1.11 (1.04, 1.18), 1.09 (1.02, 1.16), 1.06 (1.00, 1.13), and 1.17 (1.07, 1.28), respectively. For prelabor rupture of membranes, corresponding odds ratios were 1.00 (0.97, 1.04), 0.99 (0.96, 1.02), 0.99 (0.96, 1.03), and 0.99 (0.94, 1.04), respectively. Conclusion: Risk of preterm birth was greater for pregnancies with elevated PM2.5 exposure than other pregnancies to the same women at lower exposure. We did not observe an association between PM2.5 concentrations and prelabor rupture of membranes

Twisted accretion curtains in the intermediate polar FO Aquarii

We report on a ~37-ks XMM-Newton observation of the intermediate polar FO Aquarii, presenting X-ray and UV data from the EPIC and OM cameras. We find that the system has changed from its previously reported state of disc-overflow accretion to one of purely disc-fed accretion. We detect the previously reported `notch' feature in the X-ray spin pulse, and explain it as a partial occultation of the upper accretion pole. Maximum flux of the quasi-sinusoidal UV pulse coincides with the notch, in keeping with this idea. However, an absorption dip owing to the outer accretion curtains occurs 0.27 later than the expected phase, which implies that the accretion curtains are twisted, trailing the magnetic poles. This result is the opposite of that reported in PQ Gem, where accreting field lines were found to lead the pole. We discuss how such twists relate to the accretion torques and thus the observed period changes of the white dwarfs, but find no simple connection.Comment: 7 pages, 5 figures. Accepted by MNRA

The antiphase boundary in half-metallic Heusler alloy Co2Fe(Al,Si) : atomic structure, spin polarization reversal, and domain wall effects

Atomic resolution scanning transmission electron microscopy reveals the presence of an antiphase boundary in the half-metallic Co2Fe(Al,Si) full Heusler alloy. By employing the density functional theory calculations, we show that this defect leads to reversal of the sign of the spin-polarization in the vicinity of the defect. In addition, we show that this defect reduces the strength of the exchange interactions, without changing the ferromagnetic ordering across the boundary. Atomistic spin calculations predict that this effect reduces the width of the magnetic domain wall compared to that in the bulk