3,162 research outputs found

    Infrastructure for Open Access: Mechanics, Economics, Politics

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    Using the Pennsylvania State University Libraries as a case study, this essay explores the development of a library-based open access publishing program, and illustrates how open access library publishing can facilitate open access models by providing additional infrastructure for the dissemination of scholarly content

    The relationship between biophysical variables and halocarbon distributions in the waters of the Amundsen and Ross Seas, Antarctica

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    Little is known regarding the distribution of volatile halogenated organic compounds (halocarbons) in Antarctic waters and their relation to biophysical variables. During the austral summer (December to January) in 2007-08 halocarbon and pigment concentrations were measured in the Amundsen (100-130 degrees W) and Ross Sea (158 degrees W-160 degrees E). In addition, halocarbons were determined in air, snow and sea ice. The distribution of halocarbons was influenced to a large extent by sea ice, and to a much lesser extent by pelagic biota. Concentrations of naturally produced halocarbons were elevated in the surface mixed layer in ice covered areas compared to open waters in polynyas and in the bottom waters of the Ross Sea. Higher concentrations of halocarbons were also found in sea ice brine compared to the surface waters. Incubations of snow revealed an additional source of halocarbons. The distribution of halocarbons also varied considerably between the Amundsen and Ross Seas, mainly due to the different oceanographic settings. For iodinated compounds, weak correlations were found with the presence of pigments indicative of Phaeocystis, mainly in the Ross Sea. Surface waters of the Amundsen and Ross Seas are a sink for bromoform (saturation anomalies, SA, -83 to 11%), whereas sea ice was found to be both a source and sink (SA -61-97%). In contrast, both surface waters and sea ice were found to be a source of chloroiodomethane (SA -6-1 200% and 91-22 000 resp.). Consequently, polar waters can have a substantial impact on global halocarbon budgets and need to be included in large-scale assessments. (C) 2012 Elsevier B.V. All rights reserved

    State Methamphetamine Precursor Policies and Changes in Small Toxic Lab Methamphetamine Production

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    Domestic production of methamphetamine in small toxic labs (STLs) results in significant community safety and health consequences. This paper examines the effects of state-level policies implemented in the middle of the last decade in reaction to a rapid increase in STL labs. These policies focused on controlling access to the methamphetamine precursor chemicals ephedrine and pseudoephedrine and the relationship of such policies with actual STL seizure rates. Data include (a) primary legal research on state laws/regulations in all 50 states in effect as of October 1, 2005; and (b) STL seizure counts for 2004–2006. Results from random effects cross-sectional time-series regression models showed that states with the greatest reduction in STL seizures had comprehensive policies involving quantity limits on methamphetamine precursor purchases, clerk intervention requirements (such as requiring buyer identification) and regulatory agency specification for monitoring compliance and tracking multiple purchases. Criminalizing purchasing violations was not related to STL reductions

    Evaluation of Participation and Environments for Individuals with Disabilities: An Evidence-Based Practice Project Bailey

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    This Evidence-Based Practice (EBP) project considered the following question: What measures are available to evaluate participation and environmental supports and barriers for individuals with disabilities and what are their psychometric properties

    Off-Equilibrium Dynamics in Finite-Dimensional Spin Glass Models

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    The low temperature dynamics of the two- and three-dimensional Ising spin glass model with Gaussian couplings is investigated via extensive Monte Carlo simulations. We find an algebraic decay of the remanent magnetization. For the autocorrelation function C(t,tw)=[]avC(t,t_w)=[]_{av} a typical aging scenario with a t/twt/t_w scaling is established. Investigating spatial correlations we find an algebraic growth law Ο(tw)∌twα(T)\xi(t_w)\sim t_w^{\alpha(T)} of the average domain size. The spatial correlation function G(r,tw)=[<Si(tw)Si+r(tw)>2]avG(r,t_w)=[< S_i(t_w)S_{i+r}(t_w)>^2]_{av} scales with r/Ο(tw)r/\xi(t_w). The sensitivity of the correlations in the spin glass phase with respect to temperature changes is examined by calculating a time dependent overlap length. In the two dimensional model we examine domain growth with a new method: First we determine the exact ground states of the various samples (of system sizes up to 100×100100\times 100) and then we calculate the correlations between this state and the states generated during a Monte Carlo simulation.Comment: 38 pages, RevTeX, 14 postscript figure

    The efficient low-mass Seyfert MCG-05-23-016

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    The Seyfert 1.9 galaxy MCG-05-23-016 has been shown to exhibit a complex X-ray spectrum. This source has moderate X-ray luminosity, hosts a comparably low-mass black hole, but accretes at a high Eddington rate, and allows us to study a super massive black hole in an early stage. Three observations of the INTEGRAL satellite simultaneous with pointed Swift/XRT observations performed from December 2006 to June 2007 are used in combination with public data from the INTEGRAL archive to study the variability of the hard X-ray components and to generate a high-quality spectrum from 1 to 150 keV. The AGN shows little variability in the hard X-ray spectrum, with some indication of a variation in the high-energy cut-off energy ranging from 50 keV to >>100 keV, with an electron plasma temperature in the 10 - 90 keV range. The reflection component is not evident and, if present, the reflected fraction can be constrained to R < 0.3 for the combined data set. Comparison to previous observations shows that the reflection component has to be variable. No variability in the UV and optical range is observed on a time scale of 1.5 years. The hard X-ray spectrum of MCG-05-23-016 appears to be stable with the luminosity and underlying power law varying moderately and the optical/UV flux staying constant. The spectral energy distribution appears to be similar to that of Galactic black hole systems, e.g. XTE 1118+480 in the low state. The AGN exhibits a remarkably high Eddington ratio of L(bol)/L(Edd)> 0.8 (or L(bol)/L(Edd) > 0.1, if we consider a higher mass of the central engine) and, at the same time, a low cut-off energy around 70 keV. Objects like MCG-05-23-016 might indicate the early stages of super massive black holes, in which a strong accretion flow feeds the central engine.Comment: 8 pages, 5 figures, accepted for publication in A&

    Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence

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    The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the region's high HIV prevalence is accepted by many as conventional wisdom. In this paper, we evaluate the quantitative and qualitative evidence offered by the principal proponents of the concurrency hypothesis and analyze the mathematical model they use to establish the plausibility of the hypothesis

    Animal models of hypertension: a scientific statement from the American Heart Association

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    Hypertension is the most common chronic disease in the world, yet the precise cause of elevated blood pressure often cannot be determined. Animal models have been useful for unraveling the pathogenesis of hypertension and for testing novel therapeutic strategies. The utility of animal models for improving the understanding of the pathogenesis, prevention, and treatment of hypertension and its comorbidities depends on their validity for representing human forms of hypertension, including responses to therapy, and on the quality of studies in those models (such as reproducibility and experimental design). Important unmet needs in this field include the development of models that mimic the discrete hypertensive syndromes that now populate the clinic, resolution of ongoing controversies in the pathogenesis of hypertension, and the development of new avenues for preventing and treating hypertension and its complications. Animal models may indeed be useful for addressing these unmet needs

    Operational experience, improvements, and performance of the CDF Run II silicon vertex detector

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    The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.Comment: Preprint accepted for publication in Nuclear Instruments and Methods A (07/31/2013
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