7,177 research outputs found

    Telespectrograph Patent

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    Telespectrograph for analyzing upper atmosphere by tracking bodies reentering atmosphere at high velocitie

    Quantum dynamics of the avian compass

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    The ability of migratory birds to orient relative to the Earth's magnetic field is believed to involve a coherent superposition of two spin states of a radical electron pair. However, the mechanism by which this coherence can be maintained in the face of strong interactions with the cellular environment has remained unclear. This Letter addresses the problem of decoherence between two electron spins due to hyperfine interaction with a bath of spin 1/2 nuclei. Dynamics of the radical pair density matrix are derived and shown to yield a simple mechanism for sensing magnetic field orientation. Rates of dephasing and decoherence are calculated ab initio and found to yield millisecond coherence times, consistent with behavioral experiments

    Research on the application of satellite remote sensing to local, state, regional, and national programs involved with resource management and environmental quality

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    Project summaries and project reports are presented in the area of satellite remote sensing as applied to local, regional, and national environmental programs. Projects reports include: (1) Douglas County applications program; (2) vegetation damage and heavy metal concentration in new lead belt; (3) evaluating reclamation of strip-mined land; (4) remote sensing applied to land use planning at Clinton Reservoir; and (5) detailed land use mapping in Kansas City, Kansas

    Cartesian Bicategories II

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    The notion of cartesian bicategory, introduced by Carboni and Walters for locally ordered bicategories, is extended to general bicategories. It is shown that a cartesian bicategory is a symmetric monoidal bicategory

    Development program for 35 watt traveling-wave tube space amplifier Final report, 30 Jun. 1967 - 30 Sep. 1969

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    Development of 35-watt, S band, traveling wave tube amplifier for Saturn 5 instrument uni

    Information and Opportunistic Behavior in Federal Crop Insurance Programs

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    Opportunistic behavior in crop insurance can arise due to asymmetric information between producers and the Federal Crop Insurance Corporation. Producers who insure fields using transitional yields based on county average yields or who select options such as buy-up coverage or revenue insurance may increase their return from crop insurance. Using field-level crop insurance contract data for several crops in five growing regions, we find evidence that producers can profit from using buy-up coverage, revenue insurance, and transitional yields and that the level of producer opportunism is crop but not necessarily land-quality specific and is greater due to premium subsidization.opportunistic behavior, crop insurance, buy-up, revenue, transitional yields

    EST analysis of male accessory glands from Heliconius butterflies with divergent mating systems

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    <p>Abstract</p> <p>Background</p> <p><it>Heliconius </it>butterflies possess a remarkable diversity of phenotypes, physiologies, and behaviors that has long distinguished this genus as a focal taxon in ecological and evolutionary research. Recently <it>Heliconius </it>has also emerged as a model system for using genomic methods to investigate the causes and consequences of biological diversity. One notable aspect of <it>Heliconius </it>diversity is a dichotomy in mating systems which provides an unusual opportunity to investigate the relationship between sexual selection and the evolution of reproductive proteins. As a first step in pursuing this research, we report the generation and analysis of expressed sequence tags (ESTs) from the male accessory gland of <it>H. erato </it>and <it>H. melpomene</it>, species representative of the two mating systems present in the genus <it>Heliconius</it>.</p> <p>Results</p> <p>We successfully sequenced 933 ESTs clustering into 371 unigenes from <it>H. erato </it>and 1033 ESTs clustering into 340 unigenes from <it>H. melpomene</it>. Results from the two species were very similar. Approximately a third of the unigenes showed no significant BLAST similarity (E-value <10<sup>-5</sup>) to sequences in GenBank's non-redundant databases, indicating that a large proportion of novel genes are expressed in <it>Heliconius </it>male accessory glands. In both species only a third of accessory gland unigenes were also found among genes expressed in wing tissue. About 25% of unigenes from both species encoded secreted proteins. This includes three groups of highly abundant unigenes encoding repetitive proteins considered to be candidate seminal fluid proteins; proteins encoded by one of these groups were detected in <it>H. erato </it>spermatophores.</p> <p>Conclusion</p> <p>This collection of ESTs will serve as the foundation for the future identification and evolutionary analysis of male reproductive proteins in <it>Heliconius </it>butterflies. These data also represent a significant advance in the rapidly growing collection of genomic resources available in <it>Heliconius </it>butterflies. As such, they substantially enhance this taxon as a model system for investigating questions of ecological, phenotypic, and genomic diversity.</p

    A detailed study of the photo-injection annealing of thermally diffused InP solar cells

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    A detailed analysis of the annealing of thermally diffused InP solar cells fabricated by the Nippon Mining Co. is presented. The cells were irradiated with 1 MeV electrons, and the induced degradation is measured using deep level transient spectroscopy and low temperature (86 K) IV measurements. Clear recovery of the photovoltaic parameters is observed during low temperature (T is less than 300 K) solar illuminations (1 sun, AMO) with further recovery at higher temperatures (300 less than T less than 500 K). For example, the output of a cell which was irradiated up to a fluence of 1 x 10(exp 16) cm(sup -2) was observed to recover to within 5 percent of the pre-irradiation output. An apparent correlation between the recovery of I(sub sc) and the annealing of the H4 defect and of the minority carrier trapping centers is observed. An apparent correlation between the recovery of VO, and the annealing of the H5 defect is also observed. These apparent correlations are used to develop a possible model for the mechanism of the recovery of the solar cells

    High temperature annealing of minority carrier traps in irradiated MOCVD n(+)p InP solar cell junctions

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    Deep level transient spectroscopy was used to monitor thermal annealing of trapping centers in electron irradiated n(+)p InP junctions grown by metalorganic chemical vapor deposition, at temperatures ranging from 500 up to 650K. Special emphasis is given to the behavior of the minority carrier (electron) traps EA (0.24 eV), EC (0.12 eV), and ED (0.31 eV) which have received considerably less attention than the majority carrier (hole) traps H3, H4, and H5, although this work does extend the annealing behavior of the hole traps to higher temperatures than previously reported. It is found that H5 begins to anneal above 500K and is completely removed by 630K. The electron traps begin to anneal above 540K and are reduced to about half intensity by 630K. Although they each have slightly different annealing temperatures, EA, EC, and ED are all removed by 650K. A new hole trap called H3'(0.33 eV) grows as the other traps anneal and is the only trap remaining at 650K. This annealing behavior is much different than that reported for diffused junctions
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