29,727 research outputs found

    Addressing data management training needs: a practice based approach from the UK

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    In this paper, we describe the current challenges to the effective management and preservation of research data in UK universities, and the response provided by the JISC Managing Research Data programme. This paper will discuss, inter alia, the findings and conclusions from data management training projects of the first iteration of the programme and how they informed the design of the second, paying particular attention to initiatives to develop and embed training materials

    Are All Particles Identical?

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    We consider the possibility that all particles in the world are fundamentally identical, i.e., belong to the same species. Different masses, charges, spins, flavors, or colors then merely correspond to different quantum states of the same particle, just as spin-up and spin-down do. The implications of this viewpoint can be best appreciated within Bohmian mechanics, a precise formulation of quantum mechanics with particle trajectories. The implementation of this viewpoint in such a theory leads to trajectories different from those of the usual formulation, and thus to a version of Bohmian mechanics that is inequivalent to, though arguably empirically indistinguishable from, the usual one. The mathematical core of this viewpoint is however rather independent of the detailed dynamical scheme Bohmian mechanics provides, and it amounts to the assertion that the configuration space for N particles, even N ``distinguishable particles,'' is the set of all N-point subsets of physical 3-space.Comment: 12 pages LaTeX, no figure

    Flexible Parametrization of Generalized Parton Distributions: The Chiral-Odd Sector

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    We present a physically motivated parameterization of the chiral-odd generalized parton distributions. The parametrization is an extension of our previous one in the chiral-even sector which was based on the reggeized diquark model. While for chiral even generalized distributions a quantitative fit with uncertainty estimation can be performed using deep inelastic scattering data, nucleon electromagnetic, axial and pseudoscalar form factors measurements, and all available deeply virtual Compton scattering data, the chiral-odd sector is far less constrained. While awaiting the analysis of measurements on pseudoscalar mesons exclusive electroproduction which are key for the extraction of chiral odd GPDs, we worked out a connection between the chiral-even and chiral-odd reduced helicity amplitudes using Parity transformations. The connection works for a class of models including two-components models. This relation allows us to estimate the size of the various chiral odd contributions and it opens the way for future quantitative fits.Comment: 35 pages, 18 figures, text changes, corrected typos, added fig.

    The "Unromantic Pictures" of Quantum Theory

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    I am concerned with two views of quantum mechanics that John S. Bell called ``unromantic'': spontaneous wave function collapse and Bohmian mechanics. I discuss some of their merits and report about recent progress concerning extensions to quantum field theory and relativity. In the last section, I speculate about an extension of Bohmian mechanics to quantum gravity.Comment: 37 pages LaTeX, no figures; written for special volume of J. Phys. A in honor of G.C. Ghirard

    Molecular studies on intraspecific diversity and phylogenetic position of Coniothyrium minitans

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    Simple sequence repeat (SSR)±PCR amplification using a microsatellite primer (GACA)% and ribosomal RNA gene sequencing were used to examine the intraspecific diversity in the mycoparasite Coniothyrium minitans based on 48 strains, representing eight colony types, from 17 countries world-wide. Coniothyrium cerealis, C. fuckelii and C. sporulosum were used for interspecific comparison. The SSR±PCR technique revealed a relatively low level of polymorphism within C. minitans but did allow some differentiation between strains. While there was no relationship between SSR±PCR profiles and colony type, there was some limited correlation between these profiles and country of origin. Sequences of the ITS 1 and ITS 2 regions and the 5±8S gene of rRNA genes were identical in all twenty-four strains of C. minitans examined irrespective of colony type and origin. These results indicate that C. minitans is genetically not very variable despite phenotypic differences. ITS and 5±8S rRNA gene sequence analyses showed that C. minitans had similarities of 94% with C. fuckelii and C. sporulosum (which were identical to each other) and only 64% with C. cerealis. Database searches failed to show any similarity with the ITS 1 sequence for C. minitans although the 5±8S rRNA gene and ITS 2 sequences revealed an 87% similarity with Aporospora terricola. The ITS sequence including the 5±8S rRNA gene sequence of Coniothyrium cerealis showed 91% similarity to Phaeosphaeria microscopica. Phylogenetic analyses using database information suggest that C. minitans, C. sporulosum, C. fuckelii and A. terricola cluster in one clade, grouping with Helminthosporium species and 'Leptosphaeria' bicolor. Coniothyrium cerealis grouped with Ampelomyces quisqualis and formed a major cluster with members of the Phaeosphaeriacae and Phaeosphaeria microscopica

    Shift Equivalence of Measures and the Intrinsic Structure of Shocks in the Asymmetric Simple Exclusion Process

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    We investigate properties of non-translation-invariant measures, describing particle systems on \bbz, which are asymptotic to different translation invariant measures on the left and on the right. Often the structure of the transition region can only be observed from a point of view which is random---in particular, configuration dependent. Two such measures will be called shift equivalent if they differ only by the choice of such a viewpoint. We introduce certain quantities, called translation sums, which, under some auxiliary conditions, characterize the equivalence classes. Our prime example is the asymmetric simple exclusion process, for which the measures in question describe the microscopic structure of shocks. In this case we compute explicitly the translation sums and find that shocks generated in different ways---in particular, via initial conditions in an infinite system or by boundary conditions in a finite system---are described by shift equivalent measures. We show also that when the shock in the infinite system is observed from the location of a second class particle, treating this particle either as a first class particle or as an empty site leads to shift equivalent shock measures.Comment: Plain TeX, 2 figures; [email protected], [email protected], [email protected], [email protected]
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