3,211 research outputs found

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    High temperature dielectric properties of Apical, Kapton, Peek, Teflon AF, and Upilex polymers

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    Reliable lightweight systems capable of providing electrical power at the magawatt level are a requirement for future manned space exploration missions. This can be achieved by the development of high temperature insulating materials which are not only capable of surviving the hostile space environment but can contribute to reducing the mass and weight of the heat rejection system. In this work, Apical, Upilex, Kapton, Teflon AF, and Peek polymers are characterized for AC and DC dielectric breakdown in air and in silicone oil at temperatures up to 250 C. The materials are also tested in terms of their dielectric constant and dissipation factor at high temperatures with an electrical stress of 60 Hz, 200 V/mil present. The effects of thermal aging on the properties of the films are determined after 15 hours of exposure to 200 and 250 C, each. The results obtained are discussed and conclusions are made concerning the suitability of these dielectrics for use in capacitors and cable insulations in high temperature environments

    Attention-deficit hyperactivity disorder-like traits and distractibility in the visual periphery

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    We examined the performance of non-clinical subjects with high and low levels of self-reported ADHD-like traits in a novel distractibility paradigm with far peripheral visual distractors, the likely origin of many distractors in everyday life. Subjects were tested on a Sustained Attention to Response Task with distractors appearing before some of the target/non-target stimuli. When the distractors appeared 80 ms before the targets/non-targets, participants with high levels of ADHD-like traits were less affected in their reaction times than those with lower levels. Reducing the distractor-target/non-target interval to 10 ms removed the reaction time advantage for the high group. We suggest that at 80 ms the distractors were cueing the arrival of the target/non-target and that those with high levels of ADHD-like traits were more sensitive to the cues. Increased sensitivity to stimuli in the visual periphery is consistent with hyper-responsiveness at the level of the superior colliculus

    Challenges in Integrating Biological Data Sources

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    this report, we examine the technical challenges to integration, critique the available tools and resources, and compare the cost and advantages of various methodologies. We begin by analyzing the basic steps in strict and complete integration: 1) transformation of the various schemas to a common data model; 2) matching of semantically related schema objects; 3) schema integration; 4) transformation of data to the federated database on demand; and 5) matching of semantically equivalent data. Some progress has been made on generic problems such as (1) and (3) within the wider database community, but issues of semantics (steps (2) and (5)) have only been dealt with any degree of success by domain experts within the biological community. We then look at the solution space of integration strategies as defined by two axes, the "tightness" of federation and the "degree" of instantiation, discuss where various solutions fall on this plane, and examine their cost and advantages/disadvantages. Finally, we examine technical challenges that are not -3- July 12, 199

    A Multimetric Assessment of Stream Condition in the Northern Lakes and Forests Ecoregion Using Spatially Explicit Statistical Modeling and Regional Normalization

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    We sampled fish communities, water temperature, water chemistry, physical habitat, and catchment characteristics for 94 stream sites selected randomly throughout the Northern Lakes and Forests ecoregion and used those data to explicitly model reference conditions and assess ecological stream condition at each site via a regional normalization framework. The streams we sampled were first order through fourth order, and the catchments ranged from 0.9 to 458 km2. We developed multiple linear regression (MLR) models that predicted fish community metrics, water chemistry characteristics, and local physical habitat from catchment characteristics; we used these models to compare existing conditions with the conditions that would be expected based on the regression models. Our results indicated that the fish communities were relatively unimpaired because the catchment variables associated with human‐induced land use change were important in only 1 of the 10 fish metric models. Agricultural land use was a significant variable in the MLR equation for species of Lepomis (sunfish). Agricultural land use and urban land use were both significant variables in all of the MLR models predicting water chemistry variables; urban land use was a significant variable in the MLR model predicting the percent coverage of all instream cover types. Regional normalization indicated that none of the sites were impaired based on fish community attributes. However, our analysis based on water chemistry metrics indicated that 22– 35% of the sites were impaired and that, based on physical habitat, 6–14% of the sites were impaired. A comparison with other published studies of the ecoregion suggested that the regional normalization process correctly characterized stream condition.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141590/1/tafs0697.pd

    Adultery and the Rumor Mill: les bourgeois de Molinchart and El gran galeoto

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    This article seeks to challenge interpretations of the adultery plot as a subversive current in nineteenth-century literature by examining two texts that are often dismissed by contemporary critics: Les bourgeois de Molinchart (1854), a novel by the French writer Champfleury (the pseudonym of Jules Husson), and El gran Galeoto (1881), a play by the Spanish playwright Jos, Echegaray. In each of these works, the rumor of the adultery precedes and to a large extent precipitates the infidelity at the end of the work. In committing adultery, therefore, the protagonists are not rising up against social norms so much as capitulating to the expectations of society, enacting a plot that has been projected upon them. The essay compares and contrasts the treatment of the rumor mill in the two works and examines the literary strategies that the writers use to undercut a transgressive reading of the infidelity plot

    A comprehensive collection of chicken cDNAs

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    AbstractBirds have played a central role in many biological disciplines, particularly ecology, evolution, and behavior. The chicken, as a model vertebrate, also represents an important experimental system for developmental biologists, immunologists, cell biologists, and geneticists. However, genomic resources for the chicken have lagged behind those for other model organisms, with only 1845 nonredundant full-length chicken cDNA sequences currently deposited in the EMBL databank. We describe a large-scale expressed-sequence-tag (EST) project aimed at gene discovery in chickens (http://www.chick.umist.ac.uk). In total, 339,314 ESTs have been sequenced from 64 cDNA libraries generated from 21 different embryonic and adult tissues. These were clustered and assembled into 85,486 contiguous sequences (contigs). We find that a minimum of 38% of the contigs have orthologs in other organisms and define an upper limit of 13,000 new chicken genes. The remaining contigs may include novel avian specific or rapidly evolving genes. Comparison of the contigs with known chicken genes and orthologs indicates that 30% include cDNAs that contain the start codon and 20% of the contigs represent full-length cDNA sequences. Using this dataset, we estimate that chickens have approximately 35,000 genes in total, suggesting that this number may be a characteristic feature of vertebrates

    Intoxicants and the invention of 'consumption'

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    In 1600 the word ‘consumption’ was a term of medical pathology describing the ‘wasting, petrification of things’. By 1700 it was also a term of economic discourse: ‘In commodities, the value rises as its quantity is less and vent greater, which depends upon it being preferred in its consumption’. The article traces the emergence of this key category of economic analysis to debates over the economy in the 1620s and subsequent disputes over the excise tax, showing how ‘consumption’ was an early term in the developing lexicon of political economy. In so doing the article demonstrates the important role of ‘intoxicants’ – i.e. addictive and intoxicating commodities like alcohols and tobaccos – in shaping these early meanings and uses of ‘consumption’. It outlines the discursive importance of intoxicants, both as the foci for discussions of ‘superfluous’ and ‘necessary’ consumption and the target of legislation on consumption. And it argues that while these discussions had an ideological dimension, or dimensions, they were also responses to material increases in the volume and diversity of intoxicants in early seventeenth-century England. By way of conclusion the article suggests the significance of the Low Countries as a point of reference for English writers, as well as a more capacious and semantically sensitive approach to changes in early-modern consumption practices
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