Improved Pseudofermion Approach for All-Point Propagators

Quark propagators with arbitrary sources and sinks can be obtained more efficiently using a pseudofermion method with a mode-shifted action. Mode-shifting solves the problem of critical slowing down (for light quarks) induced by low eigenmodes of the Dirac operator. The method allows the full physical content of every gauge configuration to be extracted, and should be especially helpful for unquenched QCD calculations. The method can be applied for all the conventional quark actions: Wilson, Sheikoleslami-Wohlert, Kogut-Susskind, as well as Ginsparg-Wilson compliant overlap actions. The statistical properties of the method are examined and examples of physical processes under study are presented.Comment: LateX, 26 pages, 10 eps figure

The usefulness of higher-order constitutive relations for describing the Knudsen layer

The Knudsen layer is an important rarefaction phenomenon in gas flows in and around microdevices. Its accurate and efficient modeling is of critical importance in the design of such systems and in predicting their performance. In this paper we investigate the potential that higher-order continuum equations may have to model the Knudsen layer, and compare their predictions to high-accuracy DSMC (direct simulation Monte Carlo) data, as well as a standard result from kinetic theory. We find that, for a benchmark case, the most common higher-order continuum equation sets (Grad's 13 moment, Burnett, and super-Burnett equations) cannot capture the Knudsen layer. Variants of these equation families have, however, been proposed and some of them can qualitatively describe the Knudsen layer structure. To make quantitative comparisons, we obtain additional boundary conditions (needed for unique solutions to the higher-order equations) from kinetic theory. However, we find the quantitative agreement with kinetic theory and DSMC data is only slight

Capturing the Knudsen layer in continuum-fluid models of non-equilibrium gas flows

In hypersonic aerodynamics and microflow device design, the momentum and energy fluxes to solid surfaces are often of critical importance. However, these depend on the characteristics of the Knudsen layer - the region of local non-equilibrium existing up to one or two molecular mean free paths from the wall in any gas flow near a surface. While the Knudsen layer has been investigated extensively using kinetic theory, the ability to capture it within a continuum-fluid formulation (in conjunction with slip boundary conditions) suitable for current computational fluid dynamics toolboxes would offer distinct and practical computational advantages

USAID Contributes to Building National Capacity to Strengthen Food Security: An Example from Mali

Food Security and Poverty, Downloads May 2008-July 2009: 13,

Ammonia uptake and release in the MnX₂–NH₃ (X = Cl, Br) systems and structure of the Mn(NH₃)nX₂ (n = 6, 2) ammines

Hexa-ammine complexes, Mn(NH<sub>3</sub>)<sub>6</sub>X<sub>2</sub> (X = Cl, Br), have been synthesized by ammoniation of the corresponding transition metal halide and characterized by Powder X-ray diffraction (PXRD) and Raman spectroscopy. The hexa-ammine complexes are isostructural (Cubic,Fm-3m, Z = 4; a = 10.2742(6) Å and 10.527(1) Å for X = Cl, Br respectively). Temperature programmed desorption (TPD) demonstrated that ammonia release from Mn(NH<sub>3</sub>)<sub>6</sub>X<sub>2</sub> complexes occurred in three stages corresponding to the release of 4, 1 and 1 NH<sub>3</sub> equivalents respectively. The chloride and bromide both exhibit a deammoniation onset temperature below 323 K. The di-ammoniates from the first desorption step were isolated during TPD measurements and their crystal structures determined by Rietveld refinement against PXRD data (X = Cl: orthorhombicCmmm, a = 8.1991(9) Å, b = 8.2498(7) Å, c = 3.8212(4) Å, Z = 2; X = Br: orthorhombic Pbam, a = 6.0109(5) Å, b = 12.022(1) Å, c = 4.0230(2) Å, Z= 2)

The dose-response association between V̇O2peak and self-reported physical activity in children

This is an accepted manuscript of an article published by Taylor & Francis in Journal of Sports Sciences on 13/05/2020, available online: https://doi.org/10.1080/02640414.2020.1756682 The accepted version of the publication may differ from the final published version.© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. Background: Previous research into the association between aerobic fitness and physical activity in children is equivocal. However, previous research has always assumed that such an association was linear. This study sought to characterize the dose–response association between physical activity and aerobic fitness and to assess whether this association is linear or curvilinear and varies by sex, age and weight status. Methods: Physical activity (assess using the Physical Activity Questionnaire), aerobic fitness (20 m shuttle-run), BMI, screen-time and socio-demographic data were collected at ages 12, 14 and 16 years in (n = 1422) volunteers from 9 English schools. Multilevel-regression modelling was used to analyse the longitudinal data. Results: The analysis identified a significant inverted “u-shaped” association between VO2max and PAQ. This relationship remained having controlling for the influences of sex, age and weight status. Daily screen time >4 hours and deprivation were also associated with being less fit (P < 0.01). Conclusions: This longitudinal study suggests that the dose–response relationship between PA and aerobic fitness in children is curvilinear. The health benefits of PA are greater in less active children and that sedentary and less active children should be encouraged to engage in PA rather than more active children to increase existing levels of PA.Published versio