2,102 research outputs found

    Dynamics and instabilities near the glass transition: From clusters to crystals

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    Molecular dynamics simulation has been used to explore the evolution, kinetics, and dynamics of a liquid–glass transition in clusters and bulk matter. We demonstrate a dynamical indicator that characterizes the onset of the glass transition in clusters and is consistent with other indicators of glass transitions in bulk systems. This criterion, based on changes in chaotic behavior as measured by the largest Liapunov exponent, reveals aspects of the microscopic processes associated with the phase change from liquid to glass, and provides a connection between the thermodynamic and dynamical behavior of systems and their multidimensional potential surfaces

    A global map to aid the identification and screening of critical habitat for marine industries

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    Marine industries face a number of risks that necessitate careful analysis prior to making decisions on the siting of operations and facilities. An important emerging regulatory framework on environmental sustainability for business operations is the International Finance Corporation’s Performance Standard 6 (IFC PS6). Within PS6, identification of biodiversity significance is articulated through the concept of “Critical Habitat”, a definition developed by the IFC and detailed through criteria aligned with those that support internationally accepted biodiversity designations. No publicly available tools have been developed in either the marine or terrestrial realm to assess the likelihood of sites or operations being located within PS6-defined Critical Habitat. This paper presents a starting point towards filling this gap in the form of a preliminary global map that classifies more than 13 million km2 of marine and coastal areas of importance for biodiversity (protected areas, Key Biodiversity Areas [KBA], sea turtle nesting sites, cold- and warm-water corals, seamounts, seagrass beds, mangroves, saltmarshes, hydrothermal vents and cold seeps) based on their overlap with Critical Habitat criteria, as defined by IFC. In total, 5798×103 km2 (1.6%) of the analysis area (global ocean plus coastal land strip) were classed as Likely Critical Habitat, and 7526×103 km2 (2.1%) as Potential Critical Habitat; the remainder (96.3%) were Unclassified. The latter was primarily due to the paucity of biodiversity data in marine areas beyond national jurisdiction and/or in deep waters, and the comparatively fewer protected areas and KBAs in these regions. Globally, protected areas constituted 65.9% of the combined Likely and Potential Critical Habitat extent, and KBAs 29.3%, not accounting for the overlap between these two features. Relative Critical Habitat extent in Exclusive Economic Zones varied dramatically between countries. This work is likely to be of particular use for industries operating in the marine and coastal realms as an early screening aid prior to in situ Critical Habitat assessment; to financial institutions making investment decisions; and to those wishing to implement good practice policies relevant to biodiversity management. Supplementary material (available online) includes other global datasets considered, documentation and justification of biodiversity feature classification, detail of IFC PS6 criteria/scenarios, and coverage calculations

    IRISS (Increasing Resilience in Surveillance Societies) FP7 European Research Project, Deliverable 3.2: Surveillance Impact Report

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    External research report produced for the European Commission as part of the FP7 IRISS project: Increasing Resilience in Surveillance Socieities, containing European case studies on the varying formats of neighbourhood watch, including the cultural and historical factors which may influence the creation of neighbourhood watch groups in the first instance. Overview of neighbourhood watch in the United Kingdom and analysis of the changing role of the police in relation to community policing and the impact which this has had on the primary purpose of neighbourhood watch organisations.This deliverable was written as part of the IRISS project which received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 285593. Additional co-authors: Alessia Ceresa, Chiara Fonio, Walter Peissl, Robert Rothman, Jaro Sterbik Lamina, Ivan Szekely, Beatrix Vissy, Wolfgang Bonß, Daniel Fischer, Gemma Galdon Clavell, Reinhard Kreissl, Alexander Neumann, Nils Zurawsk

    NLO Higgs boson production plus one and two jets using the POWHEG BOX, MadGraph4 and MCFM

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    We present a next-to-leading order calculation of Higgs boson production plus one and two jets via gluon fusion interfaced to shower Monte Carlo programs, implemented according to the POWHEG method. For this implementation we have used a new interface of the POWHEG BOX with MadGraph4, that generates the codes for generic Born and real processes automatically. The virtual corrections have been taken from the MCFM code. We carry out a simple phenomenological study of our generators, comparing them among each other and with fixed next-to-leading order results.Comment: 27 pages, 21 figure

    A Novel Motif Identified in Dependence Receptors

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    Programmed cell death signaling is a critical feature of development, cellular turnover, oncogenesis, and neurodegeneration, among other processes. Such signaling may be transduced via specific receptors, either following ligand binding—to death receptors—or following the withdrawal of trophic ligands—from dependence receptors. Although dependence receptors display functional similarities, no common structural domains have been identified. Therefore, we employed the Multiple Expectation Maximization for Motif Elicitation and the Motif Alignment and Search Tool software programs to identify a novel transmembrane motif, dubbed dependence-associated receptor transmembrane (DART) motif, that is common to all described dependence receptors. Of 3,465 human transmembrane proteins, 25 (0.7%) display the DART motif. The predicted secondary structure features an alpha helical structure, with an unusually high percentage of valine residues. At least four of the proteins undergo regulated intramembrane proteolysis. To date, we have not identified a function for this putative domain. We speculate that the DART motif may be involved in protein processing, interaction with other proteins or lipids, or homomultimerization

    Differential cross sections and polarization observables from CLAS K* photoproduction and the search for new N* states

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    The reaction gamma p -\u3e K*(+)Lambda was measured using the CLAS detector for photon energies between the threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. For the first time, spin-density matrix elements have been extracted for this reaction. Differential cross sections, spin density matrix elements, and the Lambda recoil polarization are compared with theoretical predictions using the BnGa partial wave analysis. The main result is the evidence for significant contributions from N(1895) 1/2(-) and N(2100) 1/2(+) to the reaction. Branching ratios for decays into K*Lambda for these resonances and further resonances are reported. (C) 2017 The Author. Published by Elsevier B.V

    Photon beam asymmetry Sigma for eta and eta \u27 photoproduction from the proton

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    Measurements of the linearly-polarized photon beam asymmetry Sigma for photoproduction from the proton of eta and eta \u27 mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the gamma p -\u3e eta p reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the gamma p -\u3e eta \u27 p reaction. For gamma p -\u3e eta p, the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For gamma p -\u3e eta \u27 p, the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn-Gatchina model strengthens the evidence for four nucleon resonances - the N(1895)1/2(-), N(1900)3/2(+), N(2100)1/2(+) and N(2120)3/2(-) resonances which presently lack the four-star status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process. (C) 2017 The Authors. Published by Elsevier B.V

    Precision measurements of g1g_1 of the proton and the deuteron with 6 GeV electrons

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    The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions

    Exclusive eta electroproduction at W \u3e 2 GeV with CLAS and transversity generalized parton distributions

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    The cross section of the exclusive eta electroproduction reaction ep -\u3e e\u27p\u27eta was measured at Jefferson Laboratorywith a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d(4) sigma/dtdQ(2) dx(B)d phi(eta) and structure functions sigma(U) = sigma(T) + epsilon sigma(L), sigma(TT), and sigma(LT), as functions of t, were obtained over a wide range of Q(2) and x(B). The eta structure functions are compared with those previously measured for pi(0) at the same kinematics. At low t, both pi(0) and eta are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. The pi(0) and eta data, when taken together, can facilitate the flavor decomposition of the transversity GPDs
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