Stopping distance for high energy jets in weakly-coupled quark-gluon plasmas

We derive a simple formula for the stopping distance for a high-energy quark traveling through a weakly-coupled quark gluon plasma. The result is given to next-to-leading-order in an expansion in inverse logarithms ln(E/T), where T is the temperature of the plasma. We also define a stopping distance for gluons and give a leading-log result. Discussion of stopping distance has a theoretical advantage over discussion of energy loss rates in that stopping distances can be generalized to the case of strong coupling, where one may not speak of individual partons.Comment: 20 pages, 4 figures [change from v1: fixed embarrassing reference error

The Mass Distribution of Stellar-Mass Black Holes

We perform a Bayesian analysis of the mass distribution of stellar-mass black holes using the observed masses of 15 low-mass X-ray binary systems undergoing Roche lobe overflow and five high-mass, wind-fed X-ray binary systems. Using Markov Chain Monte Carlo calculations, we model the mass distribution both parametrically---as a power law, exponential, gaussian, combination of two gaussians, or log-normal distribution---and non-parametrically---as histograms with varying numbers of bins. We provide confidence bounds on the shape of the mass distribution in the context of each model and compare the models with each other by calculating their relative Bayesian evidence as supported by the measurements, taking into account the number of degrees of freedom of each model. The mass distribution of the low-mass systems is best fit by a power-law, while the distribution of the combined sample is best fit by the exponential model. We examine the existence of a "gap" between the most massive neutron stars and the least massive black holes by considering the value, M_1%, of the 1% quantile from each black hole mass distribution as the lower bound of black hole masses. The best model (the power law) fitted to the low-mass systems has a distribution of lower-bounds with M_1% > 4.3 Msun with 90% confidence, while the best model (the exponential) fitted to all 20 systems has M_1% > 4.5 Msun with 90% confidence. We conclude that our sample of black hole masses provides strong evidence of a gap between the maximum neutron star mass and the lower bound on black hole masses. Our results on the low-mass sample are in qualitative agreement with those of Ozel, et al (2010).Comment: 56 pages, 22 figures, 9 tables, as accepted by Ap

Systematic review of the evidence on housing interventions for ‘housing-vulnerable’ adults and its relationship to wellbeing

Access to safe, good quality affordable housing is essential to wellbeing and housing related factors can have an important influence on neighbourliness and sense of community belonging. A recent scoping review on housing and wellbeing identified a lack of review-level evidence around the impact of housing interventions on wellbeing of people who are vulnerable to discrimination or exclusion in relation to housing (Preston et al., 2016). This systematic review was commissioned to address that gap. We synthesise and consider the quality of evidence on how housing interventions can contribute to improving the lives of adults who are vulnerable in relation to the security of their housing tenure (‘housing-vulnerable’ adults)

Marine latitude/altitude OH distributions: Comparison of Pacific Ocean observations with models

Reported here are tropical/subtropical Pacific basin OH observational data presented in a latitude/altitude geographical grid. They cover two seasons of the year (spring and fall) that reflect the timing of NASA's PEM-Tropics A (1996) and B (1999) field programs. Two different OH sensors were used to collect these data, and each instrument was mounted on a different aircraft platform (i.e., NASA's P-3B and DC-8). Collectively, these chemical snapshots of the central Pacific have revealed several interesting trends. Only modest decreases (factors of 2 to 3) were found in the levels of OH with increasing altitude (0-12 km). Similarly, only modest variations were found (factors of 1.5 to 3.5) when the data were examined as a function of latitude (30° N to 30° S). Using simultaneously recorded data for CO, O3, H2O, NO, and NMHCs, comparisons with current models were also carried out. For three out of four data subsets, the results revealed a high level of correspondence. On average, the box model results agreed with the observations within a factor of 1.5. The comparison with the three-dimensional model results was found to be only slightly worse. Overall, these results suggest that current model mechanisms capture the major photochemical processes controlling OH quite well and thus provide a reasonably good representation of OH levels for tropical marine environments. They also indicate that the two OH sensors employed during the PEM-Tropics B study generally saw similar OH levels when sampling a similar tropical marine environment. However, a modest altitude bias appears to exist between these instruments. More rigorous instrument intercomparison activity would therefore seem to be justified. Further comparisons of model predictions with observations are also recommended for nontropical marine environments as well as those involving highly elevated levels of reactive non-methane hydrocarbons. Copyright 2001 by the American Geophysical Union

Investigations into free tropospheric new particle formation in the central Canadian arctic during the winter/spring transition as part of TOPSE

In this paper, we investigate the role of in situ new particle production in the central Canadian sub-Arctic and Arctic as part of the TOPSE experiment. Airborne measurements conducted primarily in the free troposphere were made from 50° to 90°W longitude and 60° to 85°N latitude during the period from February to May 2000. Data pertinent to this paper include 3–4 nm diameter (Dp) particles, ultrafine condensation nuclei (Dp \u3e 3 nm), fine particles (0.2 \u3c Dp \u3c 3 μm), and the possible nucleation precursor, sulfuric acid, and its precursor, sulfur dioxide. For data averaged over this period, most species showed little evidence for a latitudinal trend. Fine aerosol number concentrations, however, showed a slight increase with latitude. The evolution of various species concentrations over the period of the study show that fine particles also had a consistent temporal trend, increasing at all altitudes from February to May, whereas sulfur dioxide at the surface tended to peak in late March. Ultrafine condensation nuclei and 3–4 nm particles showed no temporal trends. Little evidence for in situ new particle production was observed during the study, except for one atypical event where SO2concentrations were 3.5 ppbv, 2 orders of magnitude higher than typical levels. This paper cannot address the question of whether the observed condensation nuclei were produced in situ by a low particle production rate or transported from lower latitudes

Novel analysis of global DNA methylation in the limbic system of the bovine brain

Citation: Cantrell, B. A., McKay, S. D., Weaber, R. L., Funston, R. N., & Lachance, H. (2016). Novel analysis of global DNA methylation in the limbic system of the bovine brain. Journal of Animal Science, 94, 43-43. doi:10.2134/jas2016.94supplement443xThere has been limited research focusing on the genetic-environmental interactions in bovine brains. Global DNA methylation has been measured in brains of several species, but has yet to be examined in bovine. The objective of this study was to characterize global DNA methylation in 9 regions of the limbic system in the bovine brain: amygdala, bed nucleus of the stria terminalis, cingulate gyrus, dorsal raphe, hippocampus, hypothalamus, nucleus accumbens, periaqueductal gray, and prefrontal cortex. DNA was extracted from brain and blood samples of 6 Red Angus × Simmental steers (less than 20 mo of age), using the DNA Extraction Kit from Agilent Technologies (Santa Clara, CA) and a phenol chloroform extraction. Percent of global DNA methylation was determined using the MethylFlash Methylated DNA Quantification Kit (Colormetric) from Epigentek (Farmingdale, NY). Varying amounts of global DNA methylation were observed among the 9 functionally distinct regions of the bovine limbic system. Amygdala, bed nucleus of the stria terminalis, cingulate gyrus, dorsal raphe, periaqueductal gray, prefrontal cortex, and nucleus accumbens are all significantly different (P < 0.05) from 1 or more brain tissue type, using a paired t test in SPSS (IBM, Armonk, NY). Conversely, global DNA methylation of blood was not significantly different (P < 0.05) from any brain tissue type. This study shows significant differences in global DNA methylation among different tissue types in the limbic system of the bovine brain. Understanding the differences in global DNA methylation within different tissues in the brain will facilitate future research involving the effects of differential methylation with regard to economically important traits

Coupled evolution of BrOx-ClOx-HOx-NOx chemistry during bromine-catalyzed ozone depletion events in the arctic boundary layer

Extensive chemical characterization of ozone (O3) depletion events in the Arctic boundary layer during the TOPSE aircraft mission in March-May 2000 enables analysis of the coupled chemical evolution of bromine (BrOx), chlorine (ClOx), hydrogen oxide (HOx) and nitrogen oxide (NOx) radicals during these events. We project the TOPSE observations onto an O3 chemical coordinate to construct a chronology of radical chemistry during O3 depletion events, and we compare this chronology to results from a photochemical model simulation. Comparison of observed trends in ethyne (oxidized by Br) and ethane (oxidized by Cl) indicates that ClOx chemistry is only active during the early stage Of O3 depletion (O3 &gt; 10 ppbv). We attribute this result to the suppression of BrCl regeneration as O3 decreases. Formaldehyde and peroxy radical concentrations decline by factors of 4 and 2 respectively during O3 depletion and we explain both trends on the basis of the reaction of CH2O with Br. Observed NOx concentrations decline abruptly in the early stages Of O3 depletion and recover as O3 drops below 10 ppbv. We attribute the initial decline to BrNO3 hydrolysis in aerosol, and the subsequent recovery to suppression of BrNO3 formation as O3 drops. Under halogen-free conditions we find that HNO4 heterogeneous chemistry could provide a major NOx sink not included in standard models. Halogen radical chemistry in the model can produce under realistic conditions an oscillatory system with a period of 3 days, which we believe is the fastest oscillation ever reported for a chemical system in the atmosphere