4,458 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

    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

    Evaluation of a school-based nutrition and physical activity programme for Grade 4 learners in the Western Cape province

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    Objective: This study aimed to evaluate the effectiveness of the Making the Difference programme (MTDP), an education-and activity-based intervention for Grade 4 learners at primary schools in the Western Cape. Design: This was a cross-sectional, post-intervention survey of an existing programme, using control schools as a comparator. Setting and subjects: The study involved Western Cape primary schools in the 2009 school year. Schools were randomly sampled from two regions. Four intervention (active in the MTDP) and five control (non-participating) schools (n = 325 learners) were selected. Outcome measures: The following outcome measures were assessed using an administered questionnaire to learners: learners' knowledge of, attitudes towards, and behaviour in relation to nutrition and physical activity. Results: A small but significant improvement (eating vegetables and taking lunch boxes to school) was demonstrated with regard to self-reported behaviour in relation to nutrition in the intervention group. However, this behaviour was not explained by differences in barriers to healthy eating, self-efficacy or knowledge, which were not different between the groups, or by perceived social support, which was actually significantly increased in the control group. Groups displayed no differences in physical activity or sedentary behaviour. However, the results showed a significant difference between the groups in terms of a reduction in perceived barriers to physical activity and increased physical activity self-efficacy in the active group. Conclusion: While the MTDP only had a modest effect on the self-reported nutrition and physical activity behaviour of the learners, results regarding lower perceived barriers to physical activity and increased physical activity self-efficacy were promising

    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

    Effect of Exposure on the Mechanical Properties of Gamma MET PX

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    The effect of a service environment exposure on the mechanical properties of a high Nb content TiAl alloy, Gamma MET PX , was assessed. Gamma MET PX, like other TiAl alloys, experiences a reduction of ductility following high temperature exposure. Exposure in Ar, air, and high-purity oxygen all resulted in a loss of ductility with the ductility reduction increasing with oxygen content in the exposure atmosphere. Embrittling mechanisms, including bulk microstructural changes, moisture induced environmental embrittlement, and near surface effects were investigated. The embrittlement has been shown to be a near-surface effect, most likely due to the diffusion of oxygen into the alloy

    Glueball Spectrum and Matrix Elements on Anisotropic Lattices

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    The glueball-to-vacuum matrix elements of local gluonic operators in scalar, tensor, and pseudoscalar channels are investigated numerically on several anisotropic lattices with the spatial lattice spacing ranging from 0.1fm - 0.2fm. These matrix elements are needed to predict the glueball branching ratios in J/ψJ/\psi radiative decays which will help identify the glueball states in experiments. Two types of improved local gluonic operators are constructed for a self-consistent check and the finite volume effects are studied. We find that lattice spacing dependence of our results is very weak and the continuum limits are reliably extrapolated, as a result of improvement of the lattice gauge action and local operators. We also give updated glueball masses with various quantum numbers.Comment: 22 pages, 16 figures, revtex

    Prevalence and Characteristics Associated with Chronic Noncancer Pain in Suicide Decedents: A National Study

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    Objective: The aims were to estimate the prevalence of CNCP in suicide decedents, and compare sociodemographic and clinical characteristics of people who die by suicide (i) with and without a history of CNCP and (ii) among decedents with CNCP who are younger (<65 years) and older (65 + years). Method: We examined all closed cases of intentional deaths in Australia in 2014, utilizing the National Coronial Information System. Results: We identified 2,590 closed cases of intentional deaths in Australia in 2014 in decedents over 18 years of age. CNCP was identified in 14.6% of cases. Decedents with CNCP were more likely to be older, have more mental health and physical health problems, and fewer relationship problems, and were more likely to die by poisoning from drugs, compared with decedents without CNCP. Comparisons of older and younger decedents with CNCP found that compared to younger (<65 years) decedents with CNCP, older decedents (65 + years) were less likely to have mental health problems. Conclusions: This is the first national study to examine the characteristics of suicide deaths with a focus on people with CNCP. Primary care physicians should be aware of the increased risk for suicide in people living with CNCP, and it may be useful for clinicians to screen for CNCP among those presenting with suicidal behaviors
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