3,690 research outputs found

    Extraction of the Axial Nucleon Form Factor from Neutrino Experiments on Deuterium

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    We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers (Q2Q^2), where the spatial structure of the nucleon is important, and use the Nachtman scaling variable ξ\xi to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high Q2Q^2 where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from \numu experiments on deuterium. We obtain an updated world average value from \numud, \numubarH and pion electroproduction experiments of MAM_{A} = 1.014±0.014GeV/c21.014 \pm 0.014 GeV/c^2. Our parameterizations are useful in modeling ν\nu interactions at low energies (e.g. for \numu oscillations experiments). The predictions for high Q2Q^2 can be tested in the next generation electron and \numu scattering experiments.Comment: Presented by A. Bodek at the European Physical Society Meeting, EPS2007, Manchester, England, July 2007, 4 pages, 2 figure

    Partitioning of the global fossil CO2 sink using a 19-year trend in atmospheric O2

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    O2/N2 is measured in the Cape Grim Air Archive (CGAA), a suite of tanks filled with background air at Cape Grim, Tasmania (40.7°S, 144.8°E) between April 1978 and January 1997. Derived trends are compared with published O2/N2 records and assessed against limits on interannual variability of net terrestrial exchanges imposed by trends of δ13C in CO2. Two old samples from 1978 and 1987 and eight from 1996/97 survive critical selection criteria and give a mean 19-year trend in δ(O2/N2) of -16.7 ± 0.5 per meg yr-1, implying net storage of +2.3 ± 0.7 GtC (1015 g carbon) yr-1 of fossil fuel CO2 in the oceans and +0.2 ± 0.9 GtC yr-1 in the terrestrial biosphere. The uptake terms are consistent for both O2/N2 and δ13C tracers if the mean 13C isotopic disequilibrium flux, combining terrestrial and oceanic contributions, is 93 ± 15 GtC ‰ yr-1. Copyright 1999 by the American Geophysical Union

    PIM-1 membranes containing POSS - graphene oxide for CO2 separation

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    PIM-1 mixed matrix membranes (MMMs) were fabricated with polyhedral oligomeric silsesquioxane (POSS) and graphene oxide (GO) functionalized with POSS (GO-POSS), and tested for CO2/N2 (single gas) and CO2/CH4 (1:1, v:v gas mixture). The CO2 permeability of the best performing fresh MMM (containing 0.05 wt% GO-POSS) was ~ 12000 Barrer, which is 69% higher than that of the neat PIM-1 membrane, with about the same selectivity (CO2/CH4 selectivity ~ 12 and CO2/N2 selectivity ~ 20). In both cases, the gas separation data surpass the 2008 Robeson upper bound. In addition to the initial CO2 permeability enhancement, the use of GO-POSS is an efficient strategy to slow down physical aging. The MMM at a filler loading of 0.75 wt% showed less than half of the reduction in CO2 permeability than the neat PIM-1 membrane 160 days after preparation (26% for the MMM vs 58% for the purely polymeric one). © 2022 The Author(s

    The CSIRO Mk3L climate system model version 1.0 – Part 1: Description and evaluation

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    The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulations and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. This paper describes the model physics and software, analyses the control climatology, and evaluates the ability of the model to simulate the modern climate. <br><br> Mk3L incorporates a spectral atmospheric general circulation model, a <i>z</i>-coordinate ocean general circulation model, a dynamic-thermodynamic sea ice model and a land surface scheme with static vegetation. The source code is highly portable, and has no dependence upon proprietary software. The model distribution is freely available to the research community. A 1000-yr climate simulation can be completed in around one-and-a-half months on a typical desktop computer, with greater throughput being possible on high-performance computing facilities. <br><br> Mk3L produces realistic simulations of the larger-scale features of the modern climate, although with some biases on the regional scale. The model also produces reasonable representations of the leading modes of internal climate variability in both the tropics and extratropics. The control state of the model exhibits a high degree of stability, with only a weak cooling trend on millennial timescales. Ongoing development work aims to improve the model climatology and transform Mk3L into a comprehensive earth system model

    Mutation Testing as a Safety Net for Test Code Refactoring

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    Refactoring is an activity that improves the internal structure of the code without altering its external behavior. When performed on the production code, the tests can be used to verify that the external behavior of the production code is preserved. However, when the refactoring is performed on test code, there is no safety net that assures that the external behavior of the test code is preserved. In this paper, we propose to adopt mutation testing as a means to verify if the behavior of the test code is preserved after refactoring. Moreover, we also show how this approach can be used to identify the part of the test code which is improperly refactored

    Difference schemes with point symmetries and their numerical tests

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    Symmetry preserving difference schemes approximating second and third order ordinary differential equations are presented. They have the same three or four-dimensional symmetry groups as the original differential equations. The new difference schemes are tested as numerical methods. The obtained numerical solutions are shown to be much more accurate than those obtained by standard methods without an increase in cost. For an example involving a solution with a singularity in the integration region the symmetry preserving scheme, contrary to standard ones, provides solutions valid beyond the singular point.Comment: 26 pages 7 figure

    Testing And Data Recovery Excavations At The Jayroe Site (41HM51), Hamilton County, Texas

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    In 2003–2004, Prewitt and Associates, Inc., performed National Register of Historic Places testing and subsequent data recovery excavations at the Jayroe site (41HM51) in Hamilton County for the Texas Department of Transportation, Environmental Affairs Division, under Texas Antiquities Permit Nos. 3211 and 3405. The investigations were prompted by the planned replacement of the County Road 294 bridge at the Leon River (CSJ No. 0909-29-030), in compliance with Section 106 of the National Historic Preservation Act and its implementing regulations (36 CFR Part 800) and the Antiquities Code of Texas. Testing consisted of the excavation of 6 backhoe trenches and 19 test units, and the data recovery work consisted mainly of hand excavation of 153 contiguous 1x1-m units within a single block, with 2 backhoe trenches and 2 manual units apart from the block excavation. Combined, the testing and data recovery identified 16 cultural features interpreted as 3 open hearths, 4 shallow earth ovens or surface hearths, 8 scatters of various kinds of debris, and 1 knapping station. The excavations recovered 322 chipped stone tools, 26 cores, 6,589 pieces of unmodified debitage, 21 ground or battered stone tools, 38 potential pigment sources, 43 ceramic sherds, 15 modified bone artifacts, 7,649 animal bones, 1,200 mussel shells, and macrobotanical remains. Four analytical units are defined for the site, only one of which—the Toyah phase component— has much interpretive potential. It is interpreted as a campsite used at least several times, mostly in the a.d. 1470s, at which butchering of mostly bison and deer, late-stage lithic tool manufacture and repair, and other maintenance tasks figured prominently in the site activities. The artifacts recovered and records generated by the project are curated at the Center for Archaeological Studies, Texas State University

    Symmetry-preserving discrete schemes for some heat transfer equations

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    Lie group analysis of differential equations is a generally recognized method, which provides invariant solutions, integrability, conservation laws etc. In this paper we present three characteristic examples of the construction of invariant difference equations and meshes, where the original continuous symmetries are preserved in discrete models. Conservation of symmetries in difference modeling helps to retain qualitative properties of the differential equations in their difference counterparts.Comment: 21 pages, 4 ps figure

    Role of bulk and surface phonons in the decay of metal surface states

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    We present a comprehensive theoretical investigation of the electron-phonon contribution to the lifetime broadening of the surface states on Cu(111) and Ag(111), in comparison with high-resolution photoemission results. The calculations, including electron and phonon states of the bulk and the surface, resolve the relative importance of the Rayleigh mode, being dominant for the lifetime at small hole binding energies. Including the electron-electron interaction, the theoretical results are in excellent agreement with the measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure

    Aesthetics and literature : a problematic relation?

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    The paper argues that there is a proper place for literature within aesthetics but that care must be taken in identifying just what the relation is. In characterising aesthetic pleasure associated with literature it is all too easy to fall into reductive accounts, for example, of literature as merely "fine writing". Belleslettrist or formalistic accounts of literature are rejected, as are two other kinds of reduction, to pure meaning properties and to a kind of narrative realism. The idea is developed that literature-both poetry and prose fiction-invites its own distinctive kind of aesthetic appreciation which far from being at odds with critical practice, in fact chimes well with it
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