3,385 research outputs found

    Detection of Interstellar C_2 and C_3 in the Small Magellanic Cloud

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    We report the detection of absorption from interstellar C_2 and C_3 toward the moderately reddened star Sk 143, located in the near 'wing' region of the SMC, in optical spectra obtained with the ESO VLT/UVES. These detections of C_2 (rotational levels J=0-8) and C_3 (J=0-12) absorption in the SMC are the first beyond our Galaxy. The total abundances of C_2 and C_3 (relative to H_2) are similar to those found in diffuse Galactic molecular clouds -- as previously found for CH and CN -- despite the significantly lower average metallicity of the SMC. Analysis of the rotational excitation of C_2 yields an estimated kinetic temperature T_k ~ 25 K and a moderately high total hydrogen density n_H ~ 870 cm^-3 -- compared to the T_01 ~ 45 K and n_H ~ 85-300 cm^-3 obtained from H_2. The populations of the lower rotational levels of C_3 are consistent with an excitation temperature of about 34 K.Comment: accepted to MNRAS; 10 pages, 6 figure

    Students’ Use of Symmetry with Gauss’s Law

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    To study introductory student difficulties with electrostatics, we compared student techniques when finding the electric field for spherically symmetric and non-spherically symmetric charged conductors. We used short interviews to design a free-response and multiple-choice-multiple-response survey that was administered to students in introductory calculus-based courses. We present the survey results and discuss them in light of Singh\u27s results for Gauss\u27s Law, Collins and Ferguson\u27s epistemic forms and games, and Tuminaro\u27s extension of games and frames

    Increased leukotriene C 4 and vasogenic edema surrounding brain tumors in humans

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    Leukotrines are pharmacologically active compounds that promote vascular permeability. In this study we sought to determine whether tissue leukotriene–like immunoreactivity was increased in intracranial tumors associated with peritumoral edema. In 20 patients undergoing craniotomy tissue specimens were immediately frozen after removal and tissue leukotriene C 4 levels were determined by radioimmunoassay. An index of peritumoral edema was estimated from preoperative contrast-enhanced computed tomographic scans. There was a significant correlation between brain edema and tissue leukotriene levels ( p < 0.003). Metastatic tumors (n = 8) had the highest leukotriene C 4 level at 13.8 ± 8.5 pg/mg tissue (mean ± SE) and the highest index of edema 5.7 ± 1.8. The mean leukotriene C 4 level in the gliomas (n + 5) ws 6.2 ± 2.3 pg/mg tissue and the edema index was 2.1 ± 0.6. There was no edema and no neoplasma in he temporal lobes removed for seizure (n + 2), and their level of leukotriene C 4 was 0.4 ± 0.1 pg/mg tissue. The formation of leukotriene C 4 is stimulated by intracranial tumors. Leukotrienes increase blood–brain barrier permeability and may be important in the formation of vasogenic edema surrounding tumors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50315/1/410190613_ftp.pd

    Niagara Birds: A compendium of articles and species accounts of the birds of the Niagara Region in Ontario

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    Full colour 702 p and additional corrigendaNiagara Birds consists of some 25 articles and 368 species accounts authored by professional ornithologists and highly experienced amateur birders. An excellent account of the birds of Niagara up to the year 1965 was written by Clark Beardslee and Harold Mitchell in Birds of the Niagara Frontier Region*. Our purpose of writing Niagara Birds was to update the avian diversity in Regional Niagara over the succeeding 41-year period 1966 to 2006 and to provide a base from which to note future changes in this bird-rich and attractive corner of Ontario’s Niagara Peninsula. With topics ranging from the interaction of birds and grape growers to the effect of West Nile Virus on owls, these articles will appeal to a broad spectrum of readers. The data-filled species accounts for both common and extremely rare birds of Niagara will be of interest to the general reader, students, researchers and professional ornithologists. The design and layout of the book was created by Judie Shore of Aurora Ontario. *Beardslee, C.S., and H.D. Mitchell. 1965. Birds of the Niagara Frontier Region: An annotated check-list. Bulletin of the Buffalo Society of Natural Sciences 22:1 -478

    Directing diarrhoeal disease research towards disease-burden reduction

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    Despite gains in controlling mortality relating to diarrhoeal disease, the burden of disease remains unacceptably high. To refocus health research to target disease-burden reduction as the goal of research in child health, the Child Health and Nutrition Research Initiative developed a systematic strategy to rank health research options. This priority-setting exercise included listing of 46 competitive research options in diarrhoeal disease and their critical and quantitative appraisal by 10 experts based on five criteria for research that reflect the ability of the research to be translated into interventions and achieved disease-burden reduction. These criteria included the answerability of the research questions, the efficacy and effectiveness of the intervention resulting from the research, the maximal potential for disease-burden reduction of the interventions derived from the research, the affordability, deliverability, and sustainability of the intervention supported by the research, and the overall effect of the research-derived intervention on equity. Experts scored each research option independently to delineate the best investments for diarrhoeal disease control in the developing world to reduce the burden of disease by 2015. Priority scores obtained for health policy and systems research obtained eight of the top 10 rankings in overall scores, indicating that current investments in health research are significantly different from those estimated to be the most effective in reducing the global burden of diarrhoeal disease by 2015

    Microglial inhibition of neuroprotection by antagonists of the EP1 prostaglandin E2 receptor

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    © 2009 Carlson et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
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