80 research outputs found

    Accretion Disks Around Black Holes: Twenty Five Years Later

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    We study the progress of the theory of accretion disks around black holes in last twenty five years and explain why advective disks are the best bet in explaining varied stationary and non-stationary observations from black hole candidates. We show also that the recently proposed advection dominated flows are incorrect.Comment: 30 Latex pages including figures. Kluwer Style files included. Appearing in `Observational Evidence for Black Holes in the Universe', ed. Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland

    Virulence of 32 Salmonella Strains in Mice

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    Virulence and persistence in the BALB/c mouse gut was tested for 32 strains of Salmonella enterica for which genome sequencing is complete or underway, including 17 serovars within subspecies I (enterica), and two representatives of each of the other five subspecies. Only serovar Paratyphi C strain BAA1715 and serovar Typhimurium strain 14028 were fully virulent in mice. Three divergent atypical Enteritidis strains were not virulent in BALB/c, but two efficiently persisted. Most of the other strains in all six subspecies persisted in the mouse intestinal tract for several weeks in multiple repeat experiments although the frequency and level of persistence varied considerably. Strains with heavily degraded genomes persisted very poorly, if at all. None of the strains tested provided immunity to Typhimurium infection. These data greatly expand on the known significant strain-to-strain variation in mouse virulence and highlight the need for comparative genomic and phenotypic studies

    Is Malaysia’s banded langur, Presbytis femoralis femoralis, actually Presbytis neglectus neglectus? Taxonomic revision with new insights on the radiation history of the Presbytis species group in Southeast Asia

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    The disjunct distribution of Presbytis femoralis subspecies across Sumatra (P. f. percura), southern (P. f. femoralis) and northern (P. f. robinsoni) Peninsular Malaysia marks the unique vicariance events in the Sunda Shelf. However, the taxonomic positions and evolutionary history of P. f. femoralis are unresolved after decades of research. To elucidate this evolutionary history, we analyzed 501 base pairs of the mitochondrial HVSI gene from 25 individuals representing Malaysia’s banded langur, with the addition of 29 sequences of Asian Presbytis from Genbank. Our results revealed closer affinity of P. f. femoralis to P. m. mitrata and P. m. sumatrana while maintaining the monophyletic state of P. f. femoralis as compared to P. f. robinsoni. Two central theses were inferred from the results; (1) P. f. femoralis does not belong in the same species classification as P. f. robinsoni, and (2) P. f. femoralis is the basal lineage of the Presbytis in Peninsular Malaysia. Proving the first hypothesis through genetic analysis, we reassigned P. f. femoralis of Malaysia to Presbytis neglectus (Schlegel’s banded langur) (Schlegel in Revue Methodique, Museum d’Histoire Naturelle des Pays-Bas 7:1, 1876) following the International Code of Zoological Nomenclature (article 23.3). The ancestors of P. neglectus are hypothesized to have reached southern Peninsular Malaysia during the Pleistocene and survived in refugium along the western coast. Consequently, they radiated upward, forming P. f. robinsoni and P. siamensis resulting in the highly allopatric distribution in Peninsular Malaysia. This study has successfully resolved the taxonomic position of P. neglectus in Peninsular Malaysia while providing an alternative biogeographic theory for the Asian Presbytis

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Current benzodiazepine issues

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    This article deals with some of the recent evidence bearing on the issues of the liability of benzodiazepines to lead to abuse, dependence, and adverse behavioral effects. Reviews of epidemiological, clinical and experimental literature indicated that the previous conclusion about abuse of these drugs still holds: the vast majority of the use of benzodiazepines is appropriate. Problems of nonmedical use arise nearly exclusively among people who abuse other drugs. Nevertheless, there are reasons for concern about patients who take benzodiazepines regularly for long periods of time. These drugs can produce physiological dependence when taken chronicaly, and although this does not appear to result in dose escalation or other evidence of “psychological dependence,” physiological dependence can result in patient discomfort if drug use is abruptly discontiniued. Also, physicians are currently prescribing shorter-acting benzodiazepines in preference to longer-acting benzodiazepines. The shorter-acting drugs can produce a more intense withdrawal syndrome following chronic administration. Furthermore, rates of use of benzodiazepines increase with age, and elderly patients are more likely than younger ones to take the drug chronically. The clearest adverse effect of benzodiazepines is impairment of memory. This, too, may be particular concern in older patients whose recall in the absence of drug is typically impaired relative to younger individuals, and who are more compromised following drug administration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46347/1/213_2005_Article_BF02245824.pd

    Molecular and functional properties of P2X receptors—recent progress and persisting challenges

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    Untreated Reproductive Morbidities among Ever Married Women of Slums of Rajkot City, Gujarat: The Role of Class, Distance, Provider Attitudes, and Perceived Quality of Care

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    It is a common problem in India for women in the reproductive age group to suffer from reproductive illnesses and not seek care. This paper is an attempt to assess untreated reproductive morbidities and to study factors affecting treatment-seeking behavior among ever married women of urban slums. We selected 1,046 women of the reproductive age group (15–49 years) using two-stage cluster sampling for a community-based, cross-sectional study. From this sample, 593 responses reporting reproductive morbidity were analyzed for treatment-seeking behavior and its correlates. Information was collected on demographics, socioeconomic status, self-reported reproductive morbidity, and treatment-seeking patterns, along with reasons for not utilizing available health services, all using a pretested, structured interview schedule. Univariate and multivariate analyses were done in SPSS 15.0. In our sample, 57% of women had at least one reproductive morbidity; of these, only one third sought health care. Women belonging to the Scheduled Castes/Scheduled Tribes caste group (OR = 3.92, 95% CI 1.44–10.64), at a distance of more than 2 km from a health facility (OR = 2.67, 95% CI 1.28–5.58), and whose duration of illness was more than 1 year (OR = 14.44, 95% CI 3.66–56.87) accessed fewer reproductive health services compared to their counterparts. The present study found that a lower sense of need, the cost of care, and societal barriers were the reasons for not seeking care. Providers’ poor attitudes, poor quality of services, and long waiting times were found to be the reasons for not utilizing health facilities. The determinants for accessing reproductive health care were resources available at the household level, social factors, the availability of services, and behaviors related to health. Government facilities remained underutilized

    Density-driven interstitial water motion in sediments

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    Sediment depth distributions and fluxes of dissolved chemical substances have been interpreted as being a result of reaction, diffusion, bioturbation and irrigation1,2. However, several studies suggest that density-driven convection3 can alter the depth distribution and increase the fluxes of dissolved substances when density decreases below the sediment surface 4-7. We present here temperature-time series measurements for a freshwater lake undergoing autumn cooling. These are the first in situ observations of heat transport due to motion of interstitial waters over periods of less than 1 hour. Density, calculated from temperature, decreases with depth at the time and place that this motion occurs. © 1982 Nature Publishing Group
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