9,349 research outputs found

    Comparative verification between GEM model and official aviation terminal forecasts

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    The Generalized Exponential Markov (GEM) model uses the local standard airways observation (SAO) to predict hour-by-hour the following elements: temperature, pressure, dew point depression, first and second cloud-layer height and amount, ceiling, total cloud amount, visibility, wind, and present weather conditions. GEM is superior to persistence at all projections for all elements in a large independent sample. A minute-by-minute GEM forecasting system utilizing the Automated Weather Observation System (AWOS) is under development

    A 10-year Study of Factors Associated with Alcohol Treatment Use and Non-use in a U.S. Population Sample

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    Background This study seeks to identify changes in perceived barriers to alcohol treatment and predictors of treatment use between 1991–92 and 2001–02, to potentially help understand reported reductions in treatment use at this time. Social, economic, and health trends during these 10 years provide a context for the study. Methods Subjects were Whites, Blacks, and Hispanics. The data were from the National Longitudinal Alcohol Epidemiologic Survey (NLAES) and the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). We conducted two analyses that compared the surveys on: 1) perceived treatment barriers for subjects who thought they should get help for their drinking, and 2) variables predicting past-year treatment use in an alcohol use disorder subsample using a multi-group multivariate regression model. Results In the first analysis, those barriers that reflected negative beliefs and fears about seeking treatment as well as perceptions about the lack of need for treatment were more prevalent in 2001–02. The second analysis showed that survey year moderated the relationship between public insurance coverage and treatment use. This relationship was not statistically significant in 1991–92 but was significant and positive in 2001–02, although the effect of this change on treatment use was small. Conclusions Use of alcohol treatment in the U.S. may be affected by a number of factors, such as trends in public knowledge about treatment, social pressures to reduce drinking, and changes in the public financing of treatment

    On the stability analysis of periodic sine-Gordon traveling waves

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    We study the spectral stability properties of periodic traveling waves in the sine-Gordon equation, including waves of both subluminal and superluminal propagation velocities as well as waves of both librational and rotational types. We prove that only subluminal rotational waves are spectrally stable and establish exponential instability in the other three cases. Our proof corrects a frequently cited one given by Scott.Comment: 22 pages, 6 figure

    Laboratory Rearing of \u3ci\u3eLycaeides Melissa Samuelis\u3c/i\u3e (Lepidoptera: Lycaenidae), An Endangered Butterfly in Michigan

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    The Karner blue butterfly (Lycaeides melissa samuelis) is listed as a federally endangered species in the United States. It occurs in oak savanna and pine barren habitats from eastern Minnesota to New Hampshire. In 1994, we successfully reared Karner blue larvae under controlled laboratory conditions for experimental purposes, and report on those rearing methods here. We collected 20 female Karner blue adults of the spring generation from two areas in Michigan, and housed them in cages in an environmental chamber at 240 -26°C for 5 days. The female butterflies produced 154 eggs, of which 72 hatched in an average of 4.5 days, and 68 first instars survived. Eggs, larvae and pupae were kept in a growth chamber at 24°C. Developmental time from egg to adult averaged 26 days; the average duration of each instar ranged from 3 to 4 days, and the average pupal duration was 8 days. Thirty three lab- oratory-reared Karner blue larvae successfully completed the 4 instars, and were released as adults into maternal collection sites. Laboratory rearing may be a viable means of providing Karner blue individuals for reintroduction into areas where the species is extirpated, for supplementation of small populations, or for research. Ultimately, such methods may become an integral part in the recovery of this and other rare invertebrate species

    Cloning of the cellular receptor for amphotropic murine retroviruses reveals homology to that for gibbon ape leukemia virus

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    The host and tissue specificity of retrovirus infection is largely determined by specific cellular receptors that mediate virus entry. Genes encoding these receptors are widely distributed in the genome, and the receptors identified to date show no sequence similarity. We have identified the cellular receptor for amphotropic murine retroviruses, Ram-1, by screening a rat cDNA expression library introduced into amphotropic virus-resistant hamster cells. The 656-amino acid receptor is homologous to the gibbon ape leukemia virus receptor at both hydrophobic termini but is highly divergent in the central hydrophilic region. Both receptors appear to be integral membrane proteins having multiple membrane-spanning regions. Identification of this family of receptors will help define the evolutionary relationship between retroviruses and their cellular receptors
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