1,244 research outputs found
Cooling of the H Chondrite Parent Body: Examination and Assessment of 40Ar/39Ar Age Data
No abstract available
A comparison of short-term and long-term air pollution exposure associations with mortality in two cohorts in Scotland
Air pollutionâmortality risk estimates are generally larger at longer-term, compared with short-term, exposure time scales. We compared associations between short-term exposure to black smoke (BS) and mortality with long-term exposureâmortality associations in cohort participants and with short-term exposureâmortality associations in the general population from which the cohorts were selected. We assessed short-to-mediumâterm exposureâmortality associations in the RenfrewâPaisley and Collaborative cohorts (using nested caseâcontrol data sets), and compared them with long-term exposureâmortality associations (using a multilevel spatiotemporal exposure model and survival analyses) and short-to-mediumâterm exposureâmortality associations in the general population (using time-series analyses). For the RenfrewâPaisley cohort (15,331 participants), BS exposureâmortality associations were observed in nested caseâcontrol analyses that accounted for spatial variations in pollution exposure and individual-level risk factors. These cohort-based associations were consistently greater than associations estimated in time-series analyses using a single monitoring site to represent general population exposure {e.g., 1.8% [95% confidence interval (CI): 0.1, 3.4%] vs. 0.2% (95% CI: 0.0, 0.4%) increases in mortality associated with 10-ÎŒg/m3 increases in 3-day lag BS, respectively}. Exposureâmortality associations were of larger magnitude for longer exposure periods [e.g., 3.4% (95% CI: â0.7, 7.7%) and 0.9% (95% CI: 0.3, 1.5%) increases in all-cause mortality associated with 10-ÎŒg/m3 increases in 31-day BS in caseâcontrol and time-series analyses, respectively; and 10% (95% CI: 4, 17%) increase in all-cause mortality associated with a 10-ÎŒg/m3 increase in geometic mean BS for 1970â1979, in survival analysis]. After adjusting for individual-level exposure and potential confounders, short-term exposureâmortality associations in cohort participants were of greater magnitude than in comparable general population time-series study analyses. However, short-term exposureâmortality associations were substantially lower than equivalent long-term associations, which is consistent with the possibility of larger, more persistent cumulative effects from long-term exposures
Northwest Africa 11522: A New Paired Stone of Martian Polymict Regolith Breccia Northwest Africa 7034
No abstract available
Cooling of the H Chondrite Parent Body: Examination and Assessment of 40Ar/39Ar Age Data
No abstract available
Antiretrovirals to prevent HIV infection: Pre-and postexposure prophylaxis
More than 3 million people are now receiving antiretroviral therapy (ART) worldwide. Currently, the indications for ART depend primarily on CD4 count, blood viral burden, and clinical signs and symptoms suggesting advanced HIV disease. However, interest is increasing in ART's preventive potential. Postexposure prophylaxis following both occupational and nonoccupational exposure to HIV is the standard-of-care in many settings. Observational and ecologic studies suggest that ART administered to HIV-infected people reduces transmission within serodiscordant couples. Pre-exposure prophylaxis to prevent HIV infection is a potentially safe and intermittent intervention for very high-risk people, and clinical trials to evaluate this preventive strategy are underway. The prevention benefits of ART may begin to affect the decision of when to start therapy and add a much-needed strategy to current HIV prevention efforts
Revisiting the 40Ar/39Ar Chronology of Lunar Meteorite NWA 773 Provides New Constraints on its Diachronous Geologic History
No abstract available
The Nakhlites Sample Multiple Igneous Units: Evidence From 40Ar/39Ar Chronology And Geochemistry
No abstract available
Excited Baryon Decay Widths in Large N_c QCD
We study excited baryon decay widths in large N_c QCD. It was suggested
previously that some spin-flavor mixed-symmetric baryon states have strong
couplings of O(N_c^{-1/2}) to nucleons [implying narrow widths of O(1/N_c)], as
opposed to the generic expectation based on Witten's counting rules of an
O(N_c^0) coupling. The calculation obtaining these narrow widths was performed
in the context of a simple quark-shell model. This paper addresses the question
of whether the existence of such narrow states is a general property of large
N_c QCD. We show that a general large N_c QCD analysis does not predict such
narrow states; rather they are a consequence of the extreme simplicity of the
quark model.Comment: 9 page
The perseveration of checking thoughts and moodâasâinput hypothesis
This paper describes two experiments designed to investigate how a current model of task perseveration, the mood-as-input hypothesis, might be applied to activities relevant to compulsive checking. The mood-as-input hypothesis predicts that perseveration at an open-ended task will be determined by a combination of the âstop rulesâ adopted for the task, and the valency of the mood state in which the task is conducted. Experiment 1 required participants to generate items that should be checked for safety/security if they were leaving their home unattended. Experiment 2 used an analogue recall task, in which participants were asked to recall items from a comprehensive list of items that should be checked if they were to leave their home safe/secure. Both experiments found that perseveration at the tasks was determined by particular configurations of mood and stop rules for the task. Of most relevance to compulsive checking was the fact that facilitated perseveration occurred when participants were asked to undertake the tasks in a negative mood using âas many as canâ stop rules. Implications for the factors that develop and maintain compulsive checking are discussed
The effect of dietary calcium inclusion on broiler gastrointestinal pH: quantification and method optimization
There is little consensus as to the most appropriate methodology for the measurement of gastrointestinal pH in chickens. An experiment was conducted to establish the optimum sampling method for the determination of broiler digesta pH in birds fed differing levels of dietary calcium. Ross 308 broilers (n = 60) were fed one of two experimental diets, one containing 0.8% monocalcium phosphate and 2% limestone and one containing 0.4% monocalcium phosphate and 1% limestone. Four factors were investigated to determine the most appropriate method of measuring broiler gastrointestinal digesta pH: removal from the tract, prolonged air exposure, altering the temperature of the assay, and controlling the water content of the digesta. The conditions were assessed at bird ages from 7 to 42 d post hatch. Dietary Ca content had no significant effect on in situ pH, but it contributed towards variance in ex situ pH of both gizzard and duodenum digesta
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