3,652 research outputs found

    Solid state microelectronics tolerant to radiation and high temperature

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    The 300 C electronics technology based on JFET thick film hybrids was tested up to 10 to the 9th power rad gamma (Si) and 10 to the 15th power neutrons/sq cm. Circuits and individual components from this technology all survived this total dose although some devices required 1 hour of annealing at 200 or 300 C to regain functionality. This technology used with real time annealing should function to levels greater than 10 to the 10th power rad gamma and 10 to the 16th power n/sq cm

    A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

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    This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982). We have introduced two changes to the original protocol that both streamline the procedure and increase sample uniformity. First, we normalize all sperm volumes using freezing media that does not contain the cryoprotectant. Second, cryopreserved sperm are stored in cryovials instead of capillary tubes. The rates of sperm freezing and thawing (δ°C/time) are probably the two most critical variables to control in this procedure. For this reason, do not substitute different tubes for those specified. Working in teams of 2 it is possible to freeze the sperm of 100 males per team in ~2 hrs. Sperm cryopreserved using this protocol has an average of 25% fertility (measured as the number of viable embryos generated in an in vitro fertilization divided by the total number of eggs fertilized) and this percent fertility is stable over many years

    Decuplet Baryon Structure from Lattice QCD

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    The electromagnetic properties of the SU(3)-flavor baryon decuplet are examined within a lattice simulation of quenched QCD. Electric charge radii, magnetic moments, and magnetic radii are extracted from the E0 and M1 form factors. Preliminary results for the E2 and M3 moments are presented giving the first model independent insight to the shape of the quark distribution in the baryon ground state. As in our octet baryon analysis, the lattice results give evidence of spin-dependent forces and mass effects in the electromagnetic properties. The quark charge distribution radii indicate these effects act in opposing directions. Some baryon dependence of the effective quark magnetic moments is seen. However, this dependence in decuplet baryons is more subtle than that for octet baryons. Of particular interest are the lattice predictions for the magnetic moments of Ω\Omega^- and Δ++\Delta^{++} for which new recent experimental measurements are available. The lattice prediction of the Δ++/p\Delta^{++}/p ratio appears larger than the experimental ratio, while the lattice prediction for the Ω/p\Omega^-/p magnetic moment ratio is in good agreement with the experimental ratio.Comment: RevTeX manuscript, 34 pages plus 21 figures (available upon request

    Glueball matrix elements on anisotropic lattices

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    We describe a lattice calculation of the matrix elements relevant for glueball production in J/ψJ / \psi radiative decays. The techniques for such a calculation on anisotropic lattices with an improved action are outlined. We present preliminary results showing the efficacy of the computational method.Comment: 3 pages (LaTeX), 3 figures (PostScript), Presented at Lattice '9

    Baryon Octet to Decuplet Electromagnetic Transitions

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    The electromagnetic transition moments of the SU(3)SU(3)-flavor baryon octet to decuplet are examined within a lattice simulation of quenched QCD. The magnetic transition moment for the N  γΔN \; \gamma \to \Delta channel is found to be in agreement with recent experimental analyses. The lattice results indicate μpΔ/μp=0.88(15)\mu_{p \Delta} / \mu_p = 0.88(15). In terms of the Particle Data Group convention, fM1=0.231(41)f_{M1} = 0.231(41) GeV1/2{}^{-1/2} for p  γΔ+p \; \gamma \to \Delta^+ transitions. Lattice predictions for the hyperon M1M1 transition moments agree with those of a simple quark model. However the manner in which the quarks contribute to the transition moments in the lattice simulation is different from that anticipated by quark model calculations. The scalar quadrupole form factor exhibits a behavior consistent with previous multipole analyses. The E2/M1E2/M1 multipole transition moment ratios are also determined. The lattice results suggest REMGE2/GM1=+3±8R_{EM} \equiv -{\cal G}_{E2}/{\cal G}_{M1} = +3\pm 8 \% for p  γΔ+p \; \gamma \to \Delta^+ transitions. Of particular interest are significant nonvanishing signals for the E2/M1E2/M1 ratio in Ξ\Xi^- and Σ\Sigma^- electromagnetic transitions.Comment: PostScript file, 37 pages including figures. U. MD PP #93-085, U. KY PP #UK/92-09, TRIUMF PP #TRI-PP-92-12

    APIS: Arkansas Planning Information System

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    The Federal Water Pollution Control Act Amendments of 1972 call for the restoration and maintenance of the chemical, physical and biological integrity of the Nation\u27s waters. The Act sets forth two primary goals; 1) the elimination of the discharge of all pollutants into the navigable waters of the United States by 1985 and 2) an interim level of water quality that provides for the protection of fish, shellfish, wildlife and recreation by July 1, 1983. Section 208 of the Act mandated the development and implementation of area wide water quality management plans to achieve the goals previously mentioned

    A Lattice Study of Quark and Glue Momenta and Angular Momenta in the Nucleon

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    We report a complete calculation of the quark and glue momenta and angular momenta in the proton. These include the quark contributions from both the connected and disconnected insertions. The quark disconnected insertion loops are computed with Z4Z_4 noise, and the signal-to-noise is improved with unbiased subtractions. The glue operator is comprised of gauge-field tensors constructed from the overlap operator. The calculation is carried out on a 163×2416^3 \times 24 quenched lattice at β=6.0\beta = 6.0 for Wilson fermions with κ=0.154,0.155\kappa=0.154, 0.155, and 0.15550.1555 which correspond to pion masses at 650,538650, 538, and 478478~MeV, respectively. The chirally extrapolated uu and dd quark momentum/angular momentum fraction is found to be 0.64(5)/0.70(5)0.64(5)/0.70(5), the strange momentum/angular momentum fraction is 0.024(6)/0.023(7)0.024(6)/0.023(7), and that of the glue is 0.33(6)/0.28(8)0.33(6)/0.28(8). The previous study of quark spin on the same lattice revealed that it carries a fraction of 0.25(12)0.25(12) of proton spin. The orbital angular momenta of the quarks are then obtained from subtracting the spin from their corresponding angular momentum components. We find that the quark orbital angular momentum constitutes 0.47(13)0.47(13) of the proton spin with almost all of it coming from the disconnected insertions.Comment: Renormalization section is expanded to include more details. There are slight changes in the final numbers. A few modification and corrections are made in the rest of the tex

    Frugivory and Seed Dispersal by Carnivorans

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    Seed dispersal is critical to the ecological performance of sexually reproducing plant species and the communities that they form. The Mammalian order Carnivora provide valuable and effective seed dispersal services but tend to be overlooked in much of the seed dispersal literature. Here we review the literature on the role of Carnivorans in seed dispersal, with a literature search in the Scopus reference database. Overall, we found that Carnivorans are prolific seed dispersers. Carnivorans’ diverse and plastic diets allow them to consume large volumes of over a hundred families of fruit and disperse large quantities of seeds across landscapes. Gut passage by these taxa generally has a neutral effect on seed viability. While the overall effect of Carnivorans on seed dispersal quality is complex, Carnivorans likely increase long-distance dispersal services that may aid the ability of some plant species to persist in the face of climate change
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