4,916 research outputs found

    Cryogenic seal remains leaktight during thermal displacement

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    Cryogenic seals protect the surfaces of a plastic member in a low-pressure system subjected to extreme temperature changes. The outer seal is an aluminum expansion ring bonded to the lens outer surface and the inner seal consists of a resin-filled aluminum U-ring bonded to the inner surface

    Ecology of anthocorid (Hemipt.: Anthocoridae) predators of the pear psylla (Homopt.: Psyllidae) in the Okanagan Valley, British Columbia

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    The supposition is not valid that the disappearance of the native <i>Anthocoris melanocerus</i> from pear orchards late in the summer is because of competitive displacement by the introduced <i>A. nemoralis</i>. It is because <i>A. melanocerus</i> migrates to where prey are most abundant whereas <i>A. nemoralis</i> remains on pear. <i>A. melanocerus</i> is concentrated on willows in the spring, moves to pear when <i>Psylla pyricola</i> becomes abundant, and moves to cottonwood when aphids on it become abundant and the numbers of <i>P. pyricola</i> on pear have become low

    Heat treatment: A viable methyl bromide alternative for managing stored-product insects in food-processing facilities

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    Heat treatment involves raising and maintaining temperatures of grain storage structures, warehouses, and food-processing facilities between 50 to 60°C to manage stored-product insect species. The duration of heat treatment is application-specific and may vary from 6 h for an empty storage facility to 24 h for an entire food-processing facility. Laboratory and commercial trials with high temperatures during the last decade, especially with forced air gas heaters, have resulted in a wealth of information on (1) understanding responses of insect species and life stages to heat, (2) heat distribution within a treated area, and (3) techniques necessary for gauging effectiveness of commercial heat treatments. Insect responses vary with the temperature, among species, and within a species among life stages. Air movement and strategic placement of fans are important for eliminating cool spots.Keywords: Heat, Forced air, Flour mills, Methyl bromide alternativ

    Structurally specific thermal fluctuations identify functional sites for DNA transcription

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    We report results showing that thermally-induced openings of double stranded DNA coincide with the location of functionally relevant sites for transcription. Investigating both viral and bacterial DNA gene promoter segments, we found that the most probable opening occurs at the transcription start site. Minor openings appear to be related to other regulatory sites. Our results suggest that coherent thermal fluctuations play an important role in the initiation of transcription. Essential elements of the dynamics, in addition to sequence specificity, are nonlinearity and entropy, provided by local base-pair constraints

    A Simple Model for r-Process Scatter and Halo Evolution

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    Recent observations of heavy elements produced by rapid neutron capture (r-process) in the halo have shown a striking and unexpected behavior: within a single star, the relative abundances of r-process elements heavier than Eu are the same as the same as those of solar system matter, while across stars with similar metallicity Fe/H, the r/Fe ratio varies over two orders of magnitude. In this paper we present a simple analytic model which describes a star's abundances in terms of its ``ancestry,'' i.e., the number of nucleosynthesis events (e.g., supernova explosions) which contributed to the star's composition. This model leads to a very simple analytic expression for the abundance scatter versus Fe/H, which is in good agreement with the data and with more sophisticated numerical models. We investigate two classes of scenarios for r-process nucleosynthesis, one in which r-process synthesis events occur in only \sim 4% of supernovae but iron synthesis is ubiquitous, and one in which iron nucleosynthesis occurs in only about 9% of supernovae. (the Wasserburg- Qian model). We find that the predictions in these scenarios are similar for [Fe/H] \ga -2.5, but that these models can be readily distinguished observationally by measuring the dispersion in r/Fe at [Fe/H] \la -3.Comment: AASTeX, 21 pages, includes 4 figure

    Towards cyber-physical systems as services: the ASIP protocol

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    The development of Cyber-Physical Systems needs to address the heterogeneity of several components that interact to build a single application. In this paper we present a model to enable easy integration and interaction of micro-controllers. Specifically, we describe the Arduino Service Interface Protocol (ASIP), we provide an implementation and client libraries for Java, Racket and Erlang, together with the description of a practical example
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