HOMELESS HIGH SCHOOL STUDENTS IN AMERICA: WHO COUNTS?

After interviewing homeless high school students, the research team in a Colorado school district discovered that many students had not revealed their true living conditions (homelessness) to anyone in the school district. This research team developed an anonymous survey written around the homeless categories identified in the McKinney-Vento federal legislation. Results revealed students who identified as homeless for a portion of their high school years in numbers and percentages alarmingly higher than the district had on file. In fact, over 25 times as many homeless students were identified by this process than by the previously-used district system for identifying homelessness. An equally alarming finding is that very few students identified their homeless status to a teacher, counselor, or school administrator. This article identifies statistical patterns to predict homelessness and provides recommendations for administrative practices

Polarisation of high-energy emission in a pulsar striped wind

Recent observations of the polarisation of the optical pulses from the Crab pulsar motivated detailed comparative studies of the emission predicted by the polar cap, the outer gap and the two-pole caustics models. In this work, we study the polarisation properties of the synchrotron emission emanating from the striped wind model. We use an explicit asymptotic solution for the large-scale field structure related to the oblique split monopole and valid for the case of an ultra-relativistic plasma. This is combined with a crude model for the emissivity of the striped wind and of the magnetic field within the dissipating stripes themselves. We calculate the polarisation properties of the high-energy pulsed emission and compare our results with optical observations of the Crab pulsar. The resulting radiation is linearly polarised. In the off-pulse region, the electric vector lies in the direction of the projection on the sky of the rotation axis of the pulsar, in good agreement with the data. Other properties such as a reduced degree of polarisation and a characteristic sweep of the polarisation angle within the pulses are also reproduced.Comment: Proceedings of the 363. WE-Heraeus Seminar on: Neutron Stars and Pulsars (Posters and contributed talks) Physikzentrum Bad Honnef, Germany, May.14-19, 2006, eds. W.Becker, H.H.Huang, MPE Report 291, pp.108-11

Hydrostatic Expansion and Spin Changes During Type I X-Ray Bursts

We present calculations of the spin-down of a neutron star atmosphere due to hydrostatic expansion during a Type I X-ray burst. We show that (i) Cumming and Bildsten overestimated the spin-down of rigidly-rotating atmospheres by a factor of two, and (ii) general relativity has a small (5-10%) effect on the angular momentum conservation law. We rescale our results to different neutron star masses, rotation rates and equations of state, and present some detailed rotational profiles. Comparing with recent observations of large frequency shifts in MXB 1658-298 and 4U 1916-053, we find that the spin-down expected if the atmosphere rotates rigidly is a factor of two to three less than the observed values. If differential rotation is allowed to persist, we find that the upper layers of the atmosphere spin down by an amount comparable to the observed values; however, there is no compelling reason to expect the observed spin frequency to be that of only the outermost layers. We conclude that hydrostatic expansion and angular momentum conservation alone cannot account for the largest frequency shifts observed during Type I bursts.Comment: Submitted to the Astrophysical Journal (13 pages, including 4 figures

Estimating the impact of unsafe water, sanitation and hygiene on the global burden of disease: evolving and alternative methods.

The 2010 global burden of disease (GBD) study represents the latest effort to estimate the global burden of disease and injuries and the associated risk factors. Like previous GBD studies, this latest iteration reflects a continuing evolution in methods, scope and evidence base. Since the first GBD Study in 1990, the burden of diarrhoeal disease and the burden attributable to inadequate water and sanitation have fallen dramatically. While this is consistent with trends in communicable disease and child mortality, the change in attributable risk is also due to new interpretations of the epidemiological evidence from studies of interventions to improve water quality. To provide context for a series of companion papers proposing alternative assumptions and methods concerning the disease burden and risks from inadequate water, sanitation and hygiene, we summarise evolving methods over previous GBD studies. We also describe an alternative approach using population intervention modelling. We conclude by emphasising the important role of GBD studies and the need to ensure that policy on interventions such as water and sanitation be grounded on methods that are transparent, peer-reviewed and widely accepted

Pathogens, disease, and the social-ecological resilience of protected areas

It is extremely important for biodiversity conservation that protected areas are resilient to a range of potential future perturbations. One of the least studied influences on protected area resilience is that of disease. We argue that wildlife disease (1) is a social-ecological problem that must be approached from an interdisciplinary perspective; (2) has the potential to lead to changes in the identity of protected areas, possibly transforming them; and (3) interacts with conservation both directly (via impacts on wild animals, livestock, and people) and indirectly (via the public, conservation management, and veterinary responses). We use southern African protected areas as a case study to test a framework for exploring the connections between conservation, endemic disease, and social-ecological resilience. We first define a set of criteria for the social-ecological identity of protected areas. We then use these criteria to explore the potential impacts of selected diseases (foot-and-mouth disease, anthrax, malaria, rabies, rift valley fever, trypanosomiasis, and canine distemper) on protected area resilience. Although endemic diseases may have a number of direct impacts on both wild animals and domestic animals and people, the indirect pathways by which diseases influence social-ecological resilience also emerge as potentially important. The majority of endemic pathogens found in protected areas do not kill large numbers of wild animals or infect many people, and may even play valuable ecological roles; but occasional disease outbreaks and mortalities can have a large impact on public perceptions and disease management, potentially making protected areas unviable in one or more of their stated aims. Neighboring landowners also have a significant impact on park management decisions. The indirect effects triggered by disease in the human social and economic components of protected areas and surrounding landscapes may ultimately have a greater influence on protected area resilience than the direct ecological perturbations caused by disease

Beyond the coaches eye: Understanding the ‘how’ and ‘why’ of maturity selection biases in male academy soccer

This study explored academy football coaches’ perceptions and experiences of managing individual differences in the maturity timing of male adolescent football players in an English Premier League academy. Using a longitudinal mixed method design, 98 under 12–16 players were assessed for maturity status, growth velocities, and match performance grade. Interviews with nine respective coaches were conducted in parallel. The qualitative and quantitative data were combined to generate a contextualised richer understanding and four archetypal case studies. Findings showed coaches perceive various advantages and disadvantages to players maturing either ahead or in the delay of their peers and had different expectations of performance based upon a players maturity status; biological maturity status and timing had large implications for selection and release decisions. This study highlights the challenges of developing, managing and selecting adolescent players in elite male youth football. Biological maturation confounds talent identification and development, and academy environments need to monitor maturity status and educate coaches and selectors on the complexities and intricacies of individual differences in maturity timing

Glycated hemoglobin and associated risk factors in older adults

BACKGROUND: The aim of this study is to investigate the relationships between HbA1c and other risk factors like obesity, functional fitness, lipid profile, and inflammatory status in older adults. Epidemiological evidence suggests that HbA1c is associated with cardiovascular and ischemic heart disease risk. Excess of body weight and obesity are considered to play a central role in the development of these conditions. Age is associated with several risk factors as increased body fat and abdominal fat, deterioration of the lipid profile, diabetes, raising in inflammatory activity, or decreased functional fitness. METHODS: Data were available from 118 participants aged 65-95 years, including 72 women and 46 men. Anthropometric variables were taken, as was functional fitness, blood pressure and heart rate. Blood samples were collected after 12 h fasting, and HbA1c, hs-CRP, TG, TC, HDL-C, LDL-C, and glycaemia were calculated. Bivariate and partial correlations were performed to explore associations amongst the variables of interest. Differences between groups were explored by performing factorial analysis of variance. RESULTS: HbA1c levels ranged from 4.6%-9.4% with 93% of the cases below 6.5%. Women had higher HbA1c, glycaemia, TC, BMI, and lower and upper flexibility than men. Men had higher BW, WC, 6-min walking distance, and VO2peak than women. Age, SBP, DBP, HRrest, HRpeak, HDL-C, LDL-C, TG, TG/HDL-C ratio, Log10 hs-CRP, upper and lower strength, and agility and dynamic balance were similar in men and women. HbA1c had positive associations with glycaemia, HDL-C, TG/HDL-C, BW, WC, BMI, but not with functional fitness, TC, LDL-C, Log10 hs-CRP, PAD, or PAS. Obese participants had higher HbA1c than non-obese only when IDF and not USDHHS criteria were applied. CONCLUSIONS: Older women had higher HbA1c than men, even after controlling for BMI. HbA1c associates equally with BW, BMI or WC. Population-based criteria are recommended to classify obesity and to identify higher levels of HbA1c in obese older adults. HbA1c associates with atherogenic dyslipidemia particularly with TG and TG/HDL-C ratio, but not with TC, HDL-C, or LDL-C. HbA1c is not associated with hs-CRP, and with functional fitness and aerobic endurance

Chandra Observations of Type Ia Supernovae: Upper Limits to the X-ray Flux of SN 2002bo, SN 2002ic, SN 2005gj, and SN 2005ke

We set sensitive upper limits to the X-ray emission of four Type Ia supernovae (SNe Ia) using the Chandra X-ray Observatory. SN 2002bo, a normal, although reddened, nearby SN Ia, was observed 9.3 days after explosion. For an absorbed, high temperature bremsstrahlung model the flux limits are 3.2E-16 ergs/cm^2/s (0.5-2 keV band) and 4.1E-15 ergs/cm^2/s (2-10 keV band). Using conservative model assumptions and a 10 km/s wind speed, we derive a mass loss rate of \dot{M} ~ 2E-5 M_\odot/yr, which is comparable to limits set by the non-detection of Halpha lines from other SNe Ia. Two other objects, SN 2002ic and SN 2005gj, observed 260 and 80 days after explosion, respectively, are the only SNe Ia showing evidence for circumstellar interaction. The SN 2002ic X-ray flux upper limits are ~4 times below predictions of the interaction model currently favored to explain the bright optical emission. To resolve this discrepancy we invoke the mixing of cool dense ejecta fragments into the forward shock region, which produces increased X-ray absorption. A modest amount of mixing allows us to accommodate the Chandra upper limit. SN 2005gj is less well studied at this time. Assuming the same circumstellar environment as for SN 2002i, the X-ray flux upper limits for SN 2005gj are ~4 times below the predictions, suggesting that mixing of cool ejecta into the forward shock has also occurred here. Our reanalysis of Swift and Chandra data on SN 2005ke does not confirm a previously reported X-ray detection. The host galaxies NGC 3190 (SN 2002bo) and NGC 1371 (SN 2005ke) each harbor a low luminosity (L_X ~ 3-4E40 ergs/s) active nucleus in addition to wide-spread diffuse soft X-ray emission.Comment: 16 pages, to appear in ApJ (20 Nov 2007

Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: Systematic review and meta-regression

Objective: To assess the impact of inadequate water and sanitation on diarrhoeal disease in low- and middle-income settings. Methods: The search strategy used Cochrane Library, MEDLINE & PubMed, Global Health, Embase and BIOSIS supplemented by screening of reference lists from previously published systematic reviews, to identify studies reporting on interventions examining the effect of drinking water and sanitation improvements in low- and middle-income settings published between 1970 and May 2013. Studies including randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined were eligible. Risk of bias was assessed using a modified Ottawa-Newcastle scale. Study results were combined using meta-analysis and meta-regression to derive overall and intervention-specific risk estimates. Results: Of 6819 records identified for drinking water, 61 studies met the inclusion criteria, and of 12 515 records identified for sanitation, 11 studies were included. Overall, improvements in drinking water and sanitation were associated with decreased risks of diarrhoea. Specific improvements, such as the use of water filters, provision of high-quality piped water and sewer connections, were associated with greater reductions in diarrhoea compared with other interventions. Conclusions: The results show that inadequate water and sanitation are associated with considerable risks of diarrhoeal disease and that there are notable differences in illness reduction according to the type of improved water and sanitation implemented