26,669 research outputs found

    Recent results using all-point quark propagators

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    Pseudofermion methods for extracting all-point quark propagators are reviewed, with special emphasis on techniques for reducing or eliminating autocorrelations induced by low eigenmodes of the quark Dirac operator. Recent applications, including high statistics evaluations of hadronic current correlators and the pion form factor, are also described.Comment: LateX, 3 pages, 6 eps figures, Lattice2002(algor), corrected some typo

    Key Components and Best Practices for Environmental Impact Assessments

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    New and emerging activities pose risks to the conservation and sustainable development of ABNJ in the absence of prior assessment, and remain a significant gap under UNCLOS. Environmental impact assessments and strategic environmental assessments are widely accepted as valuable tools for incorporating environmental and social concerns into decision making processes with respect to specific projects or activities (EIAs) or policies, plans or programmes (SEAs). The development of a new international instrument to address the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction ("international Instrument") is an opportunity to incorporate best practices for EIAs and SEAs already found under a number of multilateral and regional agreements, and apply lessons learned from their application. Importantly, the new Instrument should also provide the mechanism for the assessment of cumulative impacts of activities and climate change

    Hadronic Correlators from All-point Quark Propagators

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    A method for computing all-point quark propagators is applied to a variety of processes of physical interest in lattice QCD. The method allows, for example, efficient calculation of disconnected parts and full momentum-space 2 and 3 point functions. Examples discussed include: extraction of chiral Lagrangian parameters from current correlators, the pion form factor, and the unquenched eta-prime.Comment: LATTICE01(Algorithms and Machines

    The Limits of Liability in Promoting Safe Geologic Sequestration of CO2

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    Deployment of new technologies is vital to climate change policy, but it invariably poses difficult tradeoffs. Carbon capture and storage (“CCS”), which involves the capture and permanent burial of CO2 emissions, exemplifies this problem. This article provides an overview of CCS in Part I, focusing on geologic sequestration, and analyzes the scientific work on the potential for releases of CO2 and brine from sequestrian reservoirs. Part II evaluates the comparative advantages of government regulation and common law liability. Part III examines the relative efficiencies of different doctrines of common law liability when applied to likely releases from sequestrian sites. The authors propose a hybrid legal framework in Part IV that combines a traditional regulatory regime with a novel two-tiered system of liability that is calibrated to objective site characteristics.The Kay Bailey Hutchison Center for Energy, Law, and Busines

    An airborne remote sensing system for urban air quality

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    Several NASA sponsored remote sensors and possible airborne platforms were evaluated. Outputs of dispersion models for SO2 and CO pollution in the Washington, D.C. area were used with ground station data to establish the expected performance and limitations of the remote sensors. Aircraft/sensor support requirements are discussed. A method of optimum flight plan determination was made. Cost trade offs were performed. Conclusions about the implementation of various instrument packages as parts of a comprehensive air quality monitoring system in Washington are presented

    The Populations of Comet-Like Bodies in the Solar system

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    A new classification scheme is introduced for comet-like bodies in the Solar system. It covers the traditional comets as well as the Centaurs and Edgeworth-Kuiper belt objects. At low inclinations, close encounters with planets often result in near-constant perihelion or aphelion distances, or in perihelion-aphelion interchanges, so the minor bodies can be labelled according to the planets predominantly controlling them at perihelion and aphelion. For example, a JN object has a perihelion under the control of Jupiter and aphelion under the control of Neptune, and so on. This provides 20 dynamically distinct categories of outer Solar system objects in the Jovian and trans-Jovian regions. The Tisserand parameter with respect to the planet controlling perihelion is also often roughly constant under orbital evolution. So, each category can be further sub-divided according to the Tisserand parameter. The dynamical evolution of comets, however, is dominated not by the planets nearest at perihelion or aphelion, but by the more massive Jupiter. The comets are separated into four categories -- Encke-type, short-period, intermediate and long-period -- according to aphelion distance. The Tisserand parameter categories now roughly correspond to the well-known Jupiter-family comets, transition-types and Halley-types. In this way, the nomenclature for the Centaurs and Edgeworth-Kuiper belt objects is based on, and consistent with, that for comets.Comment: MNRAS, in press, 11 pages, 6 figures (1 available as postscript, 5 as gif). Higher resolution figures available at http://www-thphys.physics.ox.ac.uk/users/WynEvans/preprints.pd

    Automorphisms of Partially Commutative Groups II: Combinatorial Subgroups

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    We define several "standard" subgroups of the automorphism group Aut(G) of a partially commutative (right-angled Artin) group and use these standard subgroups to describe decompositions of Aut(G). If C is the commutation graph of G, we show how Aut(G) decomposes in terms of the connected components of C: obtaining a particularly clear decomposition theorem in the special case where C has no isolated vertices. If C has no vertices of a type we call dominated then we give a semi-direct decompostion of Aut(G) into a subgroup of locally conjugating automorphisms by the subgroup stabilising a certain lattice of "admissible subsets" of the vertices of C. We then characterise those graphs for which Aut(G) is a product (not necessarily semi-direct) of two such subgroups.Comment: 7 figures, 63 pages. Notation and definitions clarified and typos corrected. 2 new figures added. Appendix containing details of presentation and proof of a theorem adde

    Toll-like receptor expression in C3H/HeN and C3H/HeJ mice during Salmonella enterica serovar Typhimurium infection

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    Here, we have investigated the mRNA expression of Toll-like receptor 2 (TLR-2), TLR-4, and MD-2 in spleens and livers of C3H/HeN mice (carrying wild-type TLR-4) and C3H/HeJ mice (carrying mutated TLR-4) in response to Salmonella infection. During Salmonella infections, TLR-4 is activated, leading to increased TLR-2 and decreased TLR-4 expression
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