A non-spherical core in the explosion of supernova SN 2004dj

An important and perhaps critical clue to the mechanism driving the explosion of massive stars as supernovae is provided by the accumulating evidence for asymmetry in the explosion. Indirect evidence comes from high pulsar velocities, associations of supernovae with long-soft gamma-ray bursts, and asymmetries in late-time emission-line profiles. Spectropolarimetry provides a direct probe of young supernova geometry, with higher polarization generally indicating a greater departure from spherical symmetry. Large polarizations have been measured for 'stripped-envelope' (that is, type Ic) supernovae, which confirms their non-spherical morphology; but the explosions of massive stars with intact hydrogen envelopes (type II-P supernovae) have shown only weak polarizations at the early times observed. Here we report multi-epoch spectropolarimetry of a classic type II-P supernova that reveals the abrupt appearance of significant polarization when the inner core is first exposed in the thinning ejecta (~90 days after explosion). We infer a departure from spherical symmetry of at least 30 per cent for the inner ejecta. Combined with earlier results, this suggests that a strongly non-spherical explosion may be a generic feature of core-collapse supernovae of all types, where the asphericity in type II-P supernovae is cloaked at early times by the massive, opaque, hydrogen envelope.Comment: Accepted for publication by Nature (results embargoed until 23 March 2006); 14 pages, 2 figure

Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans

Background: The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleepwake cycle has not been fully characterized. Methodology/Principal Findings: We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days) and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity ‘room ’ light (,90–150 lux) or moderate light supplemented with bright light (,10,000 lux) for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h). Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54 % (17–94%) and after bright light by 52 % (range 12–84%), as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness

First dose behavioral tolerance to phencyclidine on food-rewarded bar pressing behavior in the rat

The behavioral effects of single doses of phencyclidine (PCP) were examined in drug-naive adult male Holtzman rats trained to press a bar on a fixed ratio (4) schedule (FR 4 ), i.e., a reward of sugarsweetened milk was earned on every fourth bar press. Groups of rats (four to eight rats per group) received specific doses of PCP which were held constant for each group throughout the study. Dose-response curves for PCP given in doses of 1.0, 1.8, 2.4, and 3.2 mg/kg IP were first determined and then redetermined at weekly intervals. A drug-free interval of 7–8 days was maintained between injections given weekly over a period of 4 weeks. The final dose of PCP was administered after a 4-week drug-free period. Evidence was obtained for first dose behavioral tolerance as shown by the significantly shortened duration of suppression of bar pressing on subsequent injections. Although subsequent weekly effects of equal doses of PCP showed no significant differences, they all differed significantly from the first injection. The reduced response to PCP was shown to be due to learned behavioral tolerance as demonstrated when PCP (3.2 mg/kg IP) was given to drug-naive animals in their home cages and 1 week later given the second dose in the operant behavioral situation. Under these circumstances, the second dose of PCP showed a similarly protracted depression of FR 4 responding as other animals given the drug for the first time in the operant situation. Subsequent weekly injections in the operant situation produced similar behavioral tolerance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46412/1/213_2004_Article_BF00426513.pd

Are Cal/OSHA Regulations Protecting Farmworkers in California From Heat-Related Illness?

ObjectiveDetermine compliance with and effectiveness of California regulations in reducing farmworkers' heat-related illness (HRI) risk and identify main factors contributing to HRI.MethodsIn a cross-sectional study of Latino farmworkers, core body temperature (CBT), work rate, and environmental temperature (WBGT) were monitored over a work shift by individual ingestible thermistors, accelerometers, and weather stations, respectively. Multiple logistic modeling was used to identify risk factors for elevated CBT.ResultsAlthough farms complied with Cal/OSHA regulations, worker training of HRI prevention and hydration replacement rates were insufficient. In modeling (AOR [95% CI]) male sex (3.74 [1.22 - 11.54]), WBGT (1.22 [1.08 - 1.38]), work rate (1.004 [1.002 - 1.006]), and increased BMI (1.11 [1.10 - 1.29]) were all independently associated with elevated CBT.ConclusionRisk of HRI was exacerbated by work rate and environmental temperature despite farms following Cal/OSHA regulations

Particulate Matter, Endotoxin, and Worker Respiratory Health on Large Californian Dairies

ObjectiveTo assess respiratory exposures and lung function in a cross-sectional study of California dairy workers.MethodsExposure of 205 dairy and 45 control (vegetable processing) workers to particulate matter and endotoxin was monitored. Pre- and postshift spirometry and interviews were conducted.ResultsGeometric mean inhalable and PM2.5 concentrations were 812 and 35.3 μg/m3 versus 481.9 and 19.6 μg/m3, respectively, for dairy and control workers. Endotoxin concentrations were 329 EU/m3 or 1122 pmol/m3 and 13.5 EU/m3 or 110 pmol/m3, respectively, for dairy and control workers. In a mixed-effects model, forced vital capacity decreased across a work shift by 24.5 mL (95% confidence interval, -44.7 to -4.3; P = 0.018) with log10 (total endotoxin) and by 22.0 mL (95% confidence interval, -43.2 to -0.08; P = 0.042) per hour worked.ConclusionsModern California dairy endotoxin exposures and shift length were associated with a mild acute decrease in forced vital capacity

Cost Effectiveness of ACE Inhibitor Treatment for Patients with Type 1 Diabetes Mellitus

Objective: Current guidelines recommend treating patients with type 1 diabetes mellitus with ACE inhibitors after the onset of microalbuminuria. Recent clinical trials have shown ACE inhibitors can affect the development of nephropathy when initiated prior to the onset of microalbuminuria. Our objective is to examine the cost effectiveness of treating adults aged over 20 years with an ACE inhibitor (captopril) immediately following diagnosis of type 1 diabetes versus treating them after the onset of microalbuminuria. Design: Using a semi-Markov model, we calculated four main outcome measures: lifetime direct medical costs (discounted), QALYs, cumulative incidence of end-stage renal disease (ESRD), and number of days of ESRD over a lifetime. Medical costs are in 1999 US dollars. Setting: All analyses were from the viewpoint of a single US payer responsible for all direct medical costs, including screening for microalbuminuria, ACE inhibitor treatment (captopril), management of major diabetic complications, and routine annual medical costs not specific to diabetes. Methods: We applied the model to a hypothetical cohort of 10 Results: We estimated that the incremental cost of early use of captopril for the average adult with type 1 diabetes is $US27 Conclusion: This model, with its underlying assumptions and data, suggests that early treatment with captopril provides modest benefit at reasonable cost effectiveness, from the US single-payer perspective, in the prevention of ESRD compared with delaying treatment until diagnosis of microalbuminuria. Early treatment with other ACE inhibitors will provide similar cost effectiveness if they have equivalent efficacy, compliance and price per dose. Treatment may be considered among patients at age 20 years with new onset of type 1 diabetes. This conclusion is sensitive to the extent that ACE inhibitors delay onset of microalbuminuria. Other factors such as the patient's age and glycaemic level must be considered when deciding to initiate early treatment.ACE-inhibitors, Captopril, Cost-utility, Diabetic-nephropathies