5,043 research outputs found

    An introduction to the genus Sordaria

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    An introduction to the genus Sordari

    Effects of methoprene on extreme temperature tolerance and reproduction of Tribolium castaneum (Coleoptera: Tenebrionidae)

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    The juvenile hormone analogue methoprene is a reduced-risk insecticide. It disrupts insect development of immature stages preventing the emergence of adults. Several studies have shown that lower concentrations that permit the emergence of adults also have sub-lethal effects. Exposure to methoprene (Diacon II) at 3.33 ppm reduced the heat tolerance of Tribolium castaneum (Herbst) adults. However, it did not affect the heat tolerance of larvae at 0.07 ppm. Higher concentrations of methoprene were lethal to larvae without heat treatment. Methoprene (67 ppm) had no effect on the cold tolerance of adults. Furthermore, methoprene (0.03 ppm) did not alter cold tolerance of larvae. Exposure to 15°C for 2 weeks increased the cold tolerance of adults from 4 d to 7 d, and larvae 3 d to 5 d; however, methoprene concentrations had no effect on cold tolerance. Tribolium castaneum larvae exposed to methoprene (0.001 ppm) had lower fecundity as adults. Males were more affected than females in reducing the offspring when paired with untreated mates. These results show the potential of methoprene as an emerging insecticide and a viable alternative to currently used synthetic insecticides. The data on the effect of methoprene on extreme temperature tolerance of T. castaneum have been submitted to the Journal of Stored Products Research.Keywords: Methoprene, Extreme temperature tolerance, Reproduction, Larvae, Adult

    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

    Analysis of Offshore Wind Energy Leasing Areas for the Rhode Island/Massachusetts Wind Energy Area

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    The National Renewable Energy Laboratory (NREL), under an interagency agreement with the Bureau of Ocean Energy Management (BOEM), is providing technical assistance to BOEM on the identification and delineation of offshore leasing areas for offshore wind energy development within the Atlantic Coast Wind Energy Areas (WEAs) established by BOEM in 2012. This report focuses on NREL's evaluation of BOEM's Rhode Island/Massachusetts (RIMA) WEA leasing areas. The objective of the NREL evaluation was to assess the proposed delineation of the two leasing areas and determine if the division is reasonable and technically sound. Additionally, the evaluation aimed to identify any deficiencies in the delineation. As part of the review, NREL performed the following tasks: 1. Performed a limited review of relevant literature and RIMA call nominations. 2. Executed a quantitative analysis and comparison of the two proposed leasing areas 3. Conducted interviews with University of Rhode Island (URI) staff involved with the URI Special Area Management Plan (SAMP) 4. Prepared this draft report summarizing the key findings

    The retarding ion mass spectrometer on dynamics Explorer-A

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    An instrument designed to measure the details of the thermal plasma distribution combines the ion temperature-determining capability of the retarding potential analyzer with the compositional capabilities of the mass spectrometer and adds multiple sensor heads to sample all directions relative to the spacecraft ram directions. The retarding ion mass spectrometer, its operational modes and calibration are described as well as the data reduction plan, and the anticipated results

    The Paluxy River Footprints Revisited

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    Field research by the authors at various times between 1982 and 1989 helped expose some of the elongate impressions imbedded in alleged 108 million year old Cretaceous ledges along the Paluxy River near Glen Rose, Texas. These human-like footprints were exposed in the same horizon with theropod dinosaur ichnites, as have prints in river itself over the decades, as reported by the local residents (I, 2). In order to thoroughly document such significant discoveries, several excavations were initiated since the 1986 ICC proceedings in the search for pristine ichnites. The results of these excavations plus the observable results of many previous excavations and the aspect ratio studies of many of the footprints strongly support the hypothesis that humans and dinosaurs coexisted. Furthermore, when radiocarbon dating results are combined with the paleoanthropological studies, the most logical conclusions are that: dinosaur extinction 65 million years ago is a myth; the long ages for sedimentary rock strata formation are non-existent; dinosaur extinction could have been caused by a major worldwide catastrophe happening perhaps only thousands of years ago

    A low upper-limit on the lithium isotope ratio in HD140283

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    We have obtained a high-S/N (900-1100), high-resolving-power (R=95000) spectrum of the metal-poor subgiant HD 140283 in an effort to measure its 6Li/7Li isotope ratio. From a 1-D atmospheric analysis, we find a value consistent with zero, 6Li/7Li = 0.001, with an upper limit of 6Li/7Li < 0.026. This measurement supersedes an earlier detection (0.040 +/- 0.015(1sigma)) by one of the authors. HD 140283 provides no support for the suggestion that Population II stars may preserve their 6Li on the portion of the subgiant branch where 7Li is preserved. However, this star does not defeat the suggestion either; being at the cool end of subgiant branch of the Spite plateau, it may be sufficiently cool that 6Li depletion has already set in, or the star may be sufficiently metal poor that little Galactic production of 6Li had occurred. Continued investigation of other subgiants is necessary to test the idea. We also consider the implications of the HD 140283 upper limit in conjunction with other measurements for models of 6Li production by cosmic rays from supernovae and structure formation shocks.Comment: 8 pages, 4 figures; accepted for publication in Astronomy and Astrophysic

    Imaging the Earth's Interior: the Angular Distribution of Terrestrial Neutrinos

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    Decays of radionuclides throughout the Earth's interior produce geothermal heat, but also are a source of antineutrinos. The (angle-integrated) geoneutrino flux places an integral constraint on the terrestrial radionuclide distribution. In this paper, we calculate the angular distribution of geoneutrinos, which opens a window on the differential radionuclide distribution. We develop the general formalism for the neutrino angular distribution, and we present the inverse transformation which recovers the terrestrial radioisotope distribution given a measurement of the neutrino angular distribution. Thus, geoneutrinos not only allow a means to image the Earth's interior, but offering a direct measure of the radioactive Earth, both (1) revealing the Earth's inner structure as probed by radionuclides, and (2) allowing for a complete determination of the radioactive heat generation as a function of radius. We present the geoneutrino angular distribution for the favored Earth model which has been used to calculate geoneutrino flux. In this model the neutrino generation is dominated by decays in the Earth's mantle and crust; this leads to a very ``peripheral'' angular distribution, in which 2/3 of the neutrinos come from angles > 60 degrees away from the downward vertical. We note the possibility of that the Earth's core contains potassium; different geophysical predictions lead to strongly varying, and hence distinguishable, central intensities (< 30 degrees from the downward vertical). Other uncertainties in the models, and prospects for observation of the geoneutrino angular distribution, are briefly discussed. We conclude by urging the development and construction of antineutrino experiments with angular sensitivity. (Abstract abridged.)Comment: 25 pages, RevTeX, 7 figures. Comments welcom
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