9,651 research outputs found

    A snake of a different color: physiological color change in Arizona black rattlesnakes

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    Coloration may serve a variety of behavioral (e.g., crypsis, communication) and physiological (e.g., thermoregulation, protection) functions for terrestrial ectotherms. However, optimal coloration for a given function may vary over environments (spatial or temporal) or conflict with other functions. Physiological color change (rapid change due to movement of pigment granules within chromatophores) may be an adaptation to resolve conflicting selective pressures on coloration. The proximate factors related to physiological color change are well known in many animals, but few studies have investigated the ecological or evolutionary implications of this behavior. Here, we present alternative hypotheses for physiological color change and discuss biotic and abiotic factors that may have led to the maintenance and/or loss of this behavior among populations of Arizona black rattlesnakes (_Crotalus cerberus_). We discuss what is known about this behavior and propose to investigate the function and evolution of coloration and color change in _C. cerberus_

    The determinants of participation in a social program: Evidence from a prototypical job training program

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    This paper decomposes the participation process of a prototypical program into eligibility, awareness, application, acceptance and enrollment. With this decomposition, we determine the sources of unequal participation for different groups, and demonstrate that variables often have very different effects at different stages in the participation process. Our analysis shows that personal choices substantially affect participation and that awareness of program eligibility is a major source of variation in participation.Social program participation; job training performance standards; cream skimming; job training partnership act (JTPA)

    Public perceptions of recycled water: a survey of visitors to the London 2012 Olympic Park

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    The Old Ford Water Recycling Plant, operated by Thames Water, was used to supply non-potable recycled blackwater to some of the venues at the London 2012 Games. In an effort to learn from this experience, Thames Water commissioned a survey of visitors to the Olympic Park during the Games to explore public responses to the water recycling project. Results show a very high level of support for using non-potable recycled blackwater, both in public venues and in homes. Such findings may indicate a growing receptivity towards this technology, and show that Thames Water (and other private water companies) are well placed to encourage and even lead public discussion around the role of water reuse in the future of urban water supplies

    The Determinants of Participation in a Social Program: Evidence from a Prototypical Job Training Program

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    This paper decomposes the participation process of a prototypical program into eligibility, awareness, application, acceptance and enrollment. With this decomposition, we determine the sources of unequal participation for different groups, and demonstrate that variables often have very different effects at different stages in the participation process. Our analysis shows that personal choices substantially affect participation and that awareness of program eligibility is a major source of variation in participation.

    NGC 4314. III. Inflowing Molecular Gas Feeding a Nuclear Ring of Star Formation

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    NGC 4314 is an early-type barred galaxy containing a nuclear ring of recent star formation. We present CO(1-0) interferometer data of the bar and circumnuclear region with 2.3 x 2.2 arcsec spatial resolution and 13 km/s velocity resolution acquired at the Owens Valley Radio Observatory . These data reveal a clumpy circumnuclear ring of molecular gas. We also find a peak of CO inside the ring within 2 arcsec of the optical center that is not associated with massive star formation. We construct a rotation curve from these CO kinematic data and the mass model of Combes et al. (1992). Using this rotation curve, we have identified the location of orbital resonances in the galaxy. Assuming that the bar ends at corotation, the circumnuclear ring of star formation lies between two Inner Lindblad Resonances, while the nuclear stellar bar ends near the IILR. Deviations from circular motion are detected just beyond the CO and H-alpha ring, where the dust lanes along the leading edge of the bar intersect the nuclear ring. These non-circular motions along the minor axis correspond to radially inward streaming motions at speeds of 20 - 90 km/s and clearly show inflowing gas feeding an ILR ring. There are bright HII regions near the ends of this inflow region, perhaps indicating triggering of star formation by the inflow.Comment: 25 pages, uses aasms.sty. 7 Postscript figures, 12 JPEG figures. Figures may be retrieved from ftp://clyde.as.utexas.edu/pub/N4314COfigs.tar.g

    An application of multiattribute decision analysis to the Space Station Freedom program. Case study: Automation and robotics technology evaluation

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    The results are described of an application of multiattribute analysis to the evaluation of high leverage prototyping technologies in the automation and robotics (A and R) areas that might contribute to the Space Station (SS) Freedom baseline design. An implication is that high leverage prototyping is beneficial to the SS Freedom Program as a means for transferring technology from the advanced development program to the baseline program. The process also highlights the tradeoffs to be made between subsidizing high value, low risk technology development versus high value, high risk technology developments. Twenty one A and R Technology tasks spanning a diverse array of technical concepts were evaluated using multiattribute decision analysis. Because of large uncertainties associated with characterizing the technologies, the methodology was modified to incorporate uncertainty. Eight attributes affected the rankings: initial cost, operation cost, crew productivity, safety, resource requirements, growth potential, and spinoff potential. The four attributes of initial cost, operations cost, crew productivity, and safety affected the rankings the most
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