7,310 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

    Health and Wellness: The Shift From Managing Illness to Promoting Health

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    Examines the rise in health plan initiatives to promote wellness as a way for employers to manage costs and to engage employees in their own healthcare decisions through wellness activities, behavior modification programs, and health risk assessments

    Chiral Properties of Pseudoscalar Mesons on a Quenched 20420^4 Lattice with Overlap Fermions

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    The chiral properties of the pseudoscalar mesons are studied numerically on a quenched 20420^4 lattice with the overlap fermion. We elucidate the role of the zero modes in the meson propagators, particularly that of the pseudoscalar meson. The non-perturbative renormalization constant ZAZ_A is determined from the axial Ward identity and is found to be almost independent of the quark mass for the range of quark masses we study; this implies that the O(a2)O(a^2) error is small. The pion decay constant, fπf_{\pi}, is calculated from which we determine the lattice spacing to be 0.148 fm. We look for quenched chiral log in the pseudoscalar decay constants and the pseudoscalar masses and we find clear evidence for its presence. The chiral log parameter δ\delta is determined to be in the range 0.15 -- 0.4 which is consistent with that predicted from quenched chiral perturbation theory.Comment: Version accepted for publication by PRD. A few minor typographical errors have been corrected. 24 pages, 11 figure

    A feasibility study of signed consent for the collection of patient identifiable information for a national paediatric clinical audit database

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    Objectives: To investigate the feasibility of obtaining signed consent for submission of patient identifiable data to a national clinical audit database and to identify factors influencing the consent process and its success. Design: Feasibility study. Setting: Seven paediatric intensive care units in England. Participants: Parents/guardians of patients, or patients aged 12-16 years old, approached consecutively over three months for signed consent for submission of patient identifiable data to the national clinical audit database the Paediatric Intensive Care Audit Network (PICANet). Main outcome measures: The numbers and proportions of admissions for which signed consent was given, refused, or not obtained (form not returned or form partially completed but not signed), by age, sex, level of deprivation, ethnicity (South Asian or not), paediatric index of mortality score, length of hospital stay (days in paediatric intensive care). Results: One unit did not start and one did not fully implement the protocol, so analysis excluded these two units. Consent was obtained for 182 of 422 admissions (43%) (range by unit 9% to 84%). Most (101/182; 55%) consents were taken by staff nurses. One refusal (0.2%) was received. Consent rates were significantly better for children who were more severely ill on admission and for hospital stays of six days or more, and significantly poorer for children aged 10-14 years. Long hospital stays and children aged 10-14 years remained significant in a stepwise regression model of the factors that were significant in the univariate model. Conclusion: Systematically obtaining individual signed consent for sharing patient identifiable information with an externally located clinical audit database is difficult. Obtaining such consent is unlikely to be successful unless additional resources are specifically allocated to training, staff time, and administrative support

    The Negativity of the Overlap-Based Topological Charge Density Correlator in Pure-Glue QCD and the Non-Integrable Nature of its Contact Part

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    We calculate the lattice two-point function of topological charge density in pure-glue QCD using the discretization of the operator based on the overlap Dirac matrix. Utilizing data at three lattice spacings it is shown that the continuum limit of the correlator complies with the requirement of non-positivity at non-zero distances. For our choice of the overlap operator and the Iwasaki gauge action we find that the size of the positive core is ~2a (with a being the lattice spacing) sufficiently close to the continuum limit. This result confirms that the overlap-based topological charge density is a valid local operator over realistic backgrounds contributing to the QCD path integral, and is important for the consistency of recent results indicating the existence of a low-dimensional global brane-like topological structure in the QCD vacuum. We also confirm the divergent short-distance behavior of the correlator, and the non-integrable nature of the associated contact part.Comment: 13 pages, 5 figure

    Pion Decay Constant, ZAZ_A and Chiral Log from Overlap Fermions

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    We report our calculation of the pion decay constant fπf_\pi, the axial renormalization constant ZAZ_A, and the quenched chiral logarithms from the overlap fermions. The calculation is done on a quenched 20420^4 lattice at a=0.148a=0.148 fm using tree level tadpole improved gauge action. The smallest pion mass we reach is about 280 MeV. The lattice size is about 4 times the Compton wavelength of the lowest mass pion.Comment: Lattice2001(Hadronic Matrix Elements), 3pages, 5figure

    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
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