4,838 research outputs found
The Sunyaev-Zel'dovich temperature of the intracluster medium
The relativistic Sunyaev-Zel'dovich (SZ) effect offers a method, independent
of X-ray, for measuring the temperature of the intracluster medium (ICM) in the
hottest systems. Here, using N-body/hydrodynamic simulations of three galaxy
clusters, we compare the two quantities for a non-radiative ICM, and for one
that is subject both to radiative cooling and strong energy feedback from
galaxies. Our study has yielded two interesting results. Firstly, in all cases,
the SZ temperature is hotter than the X-ray temperature and is within ten per
cent of the virial temperature of the cluster. Secondly, the mean SZ
temperature is less affected by cooling and feedback than the X-ray
temperature. Both these results can be explained by the SZ temperature being
less sensitive to the distribution of cool gas associated with cluster
substructure. A comparison of the SZ and X-ray temperatures (measured for a
sample of hot clusters) would therefore yield interesting constraints on the
thermodynamic structure of the intracluster gas.Comment: This version accepted for publication in MNRAS following minor
revisio
The absorption of light by rough metal surfaces—A three-dimensional ray-tracing analysis
From 'River Cottage' to 'Chicken Run': Hugh Fearnley-Whttingstall and the class politics of ethical consumption
Lifestyle television provides a key site through which to explore the dilemmas of ethical consumption, as the genre shifts to consider the ethics of different consumption practices and taste cultures. UK television cook Hugh Fearnley-Whittingstall's TV programmes offer fertile ground not only for thinking about television personalities as lifestyle experts and moral entrepreneurs, but also for thinking about how the meanings and uses of their television image are inflected by genre. In this article we explore how the shift from the lifestyled downshifting narrative of the River Cottage series to the 'campaigning culinary documentary' Hugh's Chicken Run exposes issues of celebrity, class and ethics. While both series are concerned with ethical consumption, they work in different ways to reveal a distinction between 'ethical' and 'unethical' consumption practices and positions - positions that are inevitably classed
Transiting Exoplanet Yields for the Roman Galactic Bulge Time Domain Survey Predicted from Pixel-Level Simulations
The Nancy Grace Roman Space Telescope (Roman) is NASA's next astrophysics
flagship mission, expected to launch in late 2026. As one of Roman's core
community science surveys, the Galactic Bulge Time Domain Survey (GBTDS) will
collect photometric and astrometric data for over 100 million stars in the
Galactic bulge to search for microlensing planets. To assess the potential with
which Roman can detect exoplanets via transit, we developed and conducted
pixel-level simulations of transiting planets in the GBTDS. From these
simulations, we predict that Roman will find between 60,000 and
200,000 transiting planets, over an order of magnitude more planets than
are currently known. While the majority of these planets will be giants
() on close-in orbits ( au), the yield also includes
between 7,000 and 12,000 small planets (). The
yield for small planets depends sensitively on the observing cadence and season
duration, with variations on the order of 10-20% for modest changes in
either parameter, but is generally insensitive to the trade between surveyed
area and cadence given constant slew/settle times. These predictions depend
sensitively on the Milky Way's metallicity distribution function, highlighting
an opportunity to significantly advance our understanding of exoplanet
demographics, particularly across stellar populations and Galactic
environments.Comment: Accepted to ApJS; 64 pages, 18 figure
A Retrospective Database Analysis of Neonatal Morbidities to Evaluate a Composite Endpoint for Use in Preterm Labor Clinical Trials
Objective To propose and assess a composite endpoint (CE) of neonatal benefit based on neonatal mortality and morbidities by gestational age (GA) for use in preterm labor clinical trials. Study Design A descriptive, retrospective analysis of the Medical University of South Carolina Perinatal Information System database was conducted. Neonatal morbidities were assessed for inclusion in the CE based on clinical significance/risk of childhood neurodevelopmental impairment, frequency, and association with GA in a mother– neonate linked cohort, comprising women with uncomplicated singleton pregnancies delivered at !24 weeks’ GA.
Results Among 17,912 mother–neonate pairs, neonates were at a risk of numerous severe but infrequent morbidities. Clinically important, predominantly rare events were combined into a CE comprising neonatal mortality and morbidities, which decreased in frequency with increasing GA. The highest CE frequency occurred at \u3c31 weeks. High frequency of respiratory distress syndrome, bronchopulmonary dysplasia, and sepsis drove the CE. Median length of hospital stay was longer at all GAs in those with the CE compared with those without.
Conclusions Descriptive epidemiological assessment and clinical input were used to develop a CE to measure neonatal benefit, comprising clinically meaningful outcomes. These empirical data and CE allowed trials investigating tocolytics to be sized appropriately
New determination of the D0→K−π+π0 and D0→K−π+π+π− coherence factors and average strong-phase differences
AbstractMeasurements of the coherence factors (RKππ0 and RK3π) and the average strong-phase differences (δDKππ0 and δDK3π) for the decays D0→K−π+π0 and D0→K−π+π+π− are presented. These parameters are important inputs to the determination of the unitarity triangle angle γ in B∓→DK∓ decays, where D designates a D0 or D¯0 meson decaying to a common final state. The measurements are made using quantum correlated DD¯ decays collected by the CLEO-c experiment at the ψ(3770) resonance, and augment a previously published analysis by the inclusion of new events in which the signal decay is tagged by the mode D→KS0π+π−. The measurements also benefit from improved knowledge of external inputs, namely the D0D¯0 mixing parameters, rDKπ and several D-meson branching fractions. The measured values are RKππ0=0.82±0.07, δDKππ0=(164−14+20)°, RK3π=0.32−0.28+0.20 and δDK3π=(225−78+21)°. Consideration is given to how these measurements can be improved further by using the larger quantum-correlated data set collected by BESIII
Egalitarianism in surgical training: let equity prevail
This study aimed to quantify core surgical trainee (CST) differential attainment (DA) related to three cohorts; white UK graduate (White UKG) versus black and minority ethnic UKG (BME UKG) versus international medical graduates (IMGs). The primary outcome measures were annual review of competence progression (ARCP) outcome, intercollegiate Membership of the Royal College of Surgeons (iMRCS) examination pass and national training number (NTN) selection. Intercollegiate Surgical Curriculum Programme (ISCP) portfolios of 264 consecutive CSTs (2010–2017, 168 white UKG, 66 BME UKG, 30 IMG) from a single UK regional post graduate medical region (Wales) were examined. Data collected prospectively over an 8-year time period was analysed retrospectively. ARCP outcomes were similar irrespective of ethnicity or nationality (ARCP outcome 1, white UKG 60.7% vs BME UKG 62.1% vs IMG 53.3%, p=0.395). iMRCS pass rates for white UKG vs BME UKG vs IMG were 71.4% vs 71.2% vs 50.0% (p=0.042), respectively. NTN success rates for white UKG vs BME UKG vs IMG were 36.9% vs 36.4% vs 6.7% (p=0.023), respectively. On multivariable analysis, operative experience (OR 1.002, 95% CI 1.001 to 1.004, p=0.004), bootcamp attendance (OR 2.615, 95% CI 1.403 to 4.871, p=0.002), and UKG (OR 7.081, 95% CI 1.556 to 32.230, p=0.011), were associated with NTN appointment. Although outcomes related to BME DA were equitable, important DA variation was apparent among IMGs, with iMRCS pass 21.4% lower and NTN success sixfold less likely than UKG. Targeted counter measures are required to let equity prevail in UK CST programmes
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