42,749 research outputs found

    Staggered Heavy Baryon Chiral Perturbation Theory

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    Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms the order of the cubed pion mass, which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms the order of the squared lattice spacing. The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in detail. The resulting chiral forms are appropriate to lattice results obtained with operators already in use and could be used to study the restoration of taste symmetry in the continuum limit. I assume that the fourth root of the fermion determinant can be incorporated in staggered chiral perturbation theory using the replica method.Comment: 54 pages; v2: corrected discussion in Sec. III.C, conclusions unchange

    Transparency in environment impact assessment decision-making: Recent developments in Western Australia

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    Transparency in decision-making, involving the establishment of explicit goals and objectives combined with open, facilitative procedures, has recently been advocated as an important principle for effective environmental impact assessment (EIA). This paper examines recent changes to EIA practice in Western Australia that emphasise clear procedures for decision-making. Current practices focus on objectives established for relevant environmental factors identified during the screening and scoping stages of EIA. These objectives are then used as decision criteria for project decision-making following public review. An example from a recent assessment is provided. Some strengths and weaknesses of this approach to transparent EIA decision-making are also examined

    Decomposition tables for experiments. II. Two--one randomizations

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    We investigate structure for pairs of randomizations that do not follow each other in a chain. These are unrandomized-inclusive, independent, coincident or double randomizations. This involves taking several structures that satisfy particular relations and combining them to form the appropriate orthogonal decomposition of the data space for the experiment. We show how to establish the decomposition table giving the sources of variation, their relationships and their degrees of freedom, so that competing designs can be evaluated. This leads to recommendations for when the different types of multiple randomization should be used.Comment: Published in at http://dx.doi.org/10.1214/09-AOS785 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Decomposition tables for experiments I. A chain of randomizations

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    One aspect of evaluating the design for an experiment is the discovery of the relationships between subspaces of the data space. Initially we establish the notation and methods for evaluating an experiment with a single randomization. Starting with two structures, or orthogonal decompositions of the data space, we describe how to combine them to form the overall decomposition for a single-randomization experiment that is ``structure balanced.'' The relationships between the two structures are characterized using efficiency factors. The decomposition is encapsulated in a decomposition table. Then, for experiments that involve multiple randomizations forming a chain, we take several structures that pairwise are structure balanced and combine them to establish the form of the orthogonal decomposition for the experiment. In particular, it is proven that the properties of the design for such an experiment are derived in a straightforward manner from those of the individual designs. We show how to formulate an extended decomposition table giving the sources of variation, their relationships and their degrees of freedom, so that competing designs can be evaluated.Comment: Published in at http://dx.doi.org/10.1214/09-AOS717 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Solidification under zero gravity: A Long Duration Exposure Facility (LDEF) experiment for an early space shuttle mission

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    The preliminary design of two series of simple experiments the objectives of which are to determine the effect of an absence of gravity on (1) the general morphology of the structure, (2) location of ullage space, and (3) magnitude of surface tension driven convection, during the solidification of several metallic and nonmetallic systems is described. Details of the investigative approach, experimental procedure, experimental hardware, data reduction and analysis, and anticipated results are given

    Familial Ménière's disease: clinical and genetic aspects

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    ABSTRACT Background and purpose:Mre's disease is not uncommon, with an incidence in Caucasians of about one in 2000. The incidence peaks in the fifth decade. Cases are usually isolated or sporadic, but in perhaps five per cent other family members are affected. We report here the clinical and genetic characteristics of a comprehensive set of familial Mre's disease cases from the UK.Methods:Forty-six affected families were studied. All cases were diagnosed using the American Academy of Otolaryngolog 8211;Head and Neck Surgery committee on hearing and equilibrium 1995, or more stringent, criteria.Outcomes and results:Autosomal dominant inheritance with reduced penetrance was the most likely mode of inheritance overall. Apparent genetic anticipation was observed, but may also be a result of ascertainment bias given the collection strategy. There was also a slight tendency for cases to result from maternal transmission within the families in this set. The family pedigrees are presented, and the authors have also set up a website at which all the pedigrees may be viewed in greater detai

    Prospects for improved Λc\Lambda_c branching fractions

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    The experimental uncertainty on the branching fraction \b(\Lambda_c \to p K^- \pi^+) = (5.0 \pm 1.3)% has not decreased since 1998, despite a much larger data sample. Uncertainty in this quantity dominates that in many other quantities, including branching fractions of Λc\Lambda_c to other modes, branching fractions of bb-flavored baryons, and fragmentation fractions of charmed and bottom quarks. Here we advocate a lattice QCD calculation of the form factors in ΛcΛ+ν\Lambda_c \to \Lambda \ell^+ \nu_\ell (the case =e+\ell = e^+ is simpler as the mass of the lepton can be neglected). Such a calculation would yield an absolute prediction for the rate for ΛcΛ+ν\Lambda_c \to \Lambda \ell^+ \nu_\ell. When combined with the Λc\Lambda_c lifetime, it could provide a calibration for an improved set of Λc\Lambda_c branching fractions as long as the accuracy exceeds about 25%.Comment: 8 pages, 2 figures, version to be published in Phys.\ Rev.\

    A Minimal Contact Diet and Physical Activity Intervention for White-Collar Workers

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    Minimal contact lifestyle interventions with multiple components coupled with health screening have the potential to improve worker health. The purpose of this study was to test a minimal contact multiple component lifestyle diet and exercise intervention. The multiple components that were included in this project included a worksite health screening, brief counseling session, emailed newsletter, and a pedometer. In response to the intervention, participants reported an increase in green salad, fruit, and vegetable consumption as well as an increase in self-efficacy for consuming three servings of fruits and vegetables a day. Study participants also demonstrated a significant increase in physical activity as shown by their responses to the question, “During leisure time I walk.” A minimal contact multiple component worksite health promotion program with relatively high feasibility and low cost can improve workers’ health-related behaviors, and participants can become more aware of their health

    Cryogenic Fluid Management Experiment (CFME) trunnion verification testing

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    The Cryogenic Fluid Management Experiment (CFME) was designed to characterize subcritical liquid hydrogen storage and expulsion in the low-g space environment. The CFME has now become the storage and supply tank for the Cryogenic Fluid Management Facility, which includes transfer line and receiver tanks, as well. The liquid hydrogen storage and supply vessel is supported within a vacuum jacket to two fiberglass/epoxy composite trunnions which were analyzed and designed. Analysis using the limited available data indicated the trunnion was the most fatigue critical component in the storage vessel. Before committing the complete storage tank assembly to environmental testing, an experimental assessment was performed to verify the capability of the trunnion design to withstand expected vibration and loading conditions. Three tasks were conducted to evaluate trunnion integrity. The first determined the fatigue properties of the trunnion composite laminate materials. Tests at both ambient and liquid hydrogen temperatures showed composite material fatigue properties far in excess of those expected. Next, an assessment of the adequacy of the trunnion designs was performed (based on the tested material properties)
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