6,989 research outputs found

    The Specific Heat of a Ferromagnetic Film.

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    We analyze the specific heat for the O(N)O(N) vector model on a dd-dimensional film geometry of thickness LL using ``environmentally friendly'' renormalization. We consider periodic, Dirichlet and antiperiodic boundary conditions, deriving expressions for the specific heat and an effective specific heat exponent, \alpha\ef. In the case of d=3d=3, for N=1N=1, by matching to the exact exponent of the two dimensional Ising model we capture the crossover for \xi_L\ra\infty between power law behaviour in the limit {L\over\xi_L}\ra\infty and logarithmic behaviour in the limit {L\over\xi_L}\ra0 for fixed LL, where ξL\xi_L is the correlation length in the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from [email protected]

    Lactococcus lactis subsp. lactis as a natural anti-listerial agent in the mushroom industry

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    peer-reviewedMushroom growth substrates from different commercial producers of mushrooms (Agaricus bisporus) were screened for the presence of bacteria with potential for use as biocontrol agents for controlling Listeria monocytogenes in the mushroom production environment. Eight anti-listerial strains were isolated from different sources and all were identified using 16s rRNA gene sequencing as Lactococcus lactis subsp. lactis. Whole-genome sequencing of the Lc. lactis isolates indicated that strains from different sites and substrate types were highly similar. Colony MALDI-TOF mass spectrometry found that these strains were Nisin Z producers but inhibitory activity was highly influenced by the incubation conditions and was strain dependant. The biofilm forming ability of these strains was tested using a crystal violet assay and all were found to be strong biofilm formers. Growth of Lc. lactis subsp. lactis using mixed-biofilm conditions with L. monocytogenes on stainless steel resulted in a 4-log reduction of L. monocytogenes cell numbers. Additional sampling of mushroom producers showed that these anti-listerial Lc. lactis strains are commonly present in the mushroom production environment. Lc. lactis has a generally regarded as safe (GRAS) status and therefore has potential for use as an environmentally benign solution to control L. monocytogenes in order to prevent product contamination and to enhance consumer confidence in the mushroom industry

    Dimensional Crossover in the Large N Limit

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    We consider dimensional crossover for an O(N)O(N) Landau-Ginzburg-Wilson model on a dd-dimensional film geometry of thickness LL in the large NN-limit. We calculate the full universal crossover scaling forms for the free energy and the equation of state. We compare the results obtained using ``environmentally friendly'' renormalization with those found using a direct, non-renormalization group approach. A set of effective critical exponents are calculated and scaling laws for these exponents are shown to hold exactly, thereby yielding non-trivial relations between the various thermodynamic scaling functions.Comment: 25 pages of PlainTe

    The Influence of Thermal Pressure on Equilibrium Models of Hypermassive Neutron Star Merger Remnants

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    The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state, angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (~5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically-symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear equations of state, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parametrized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger.Comment: 20 pages, 12 figures. Accepted for publication in Ap

    Two new species of Marmosopus (Acari: Astigmata) from rodents of the genus Scotinomys (Cricetidae) in Central America

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    http://deepblue.lib.umich.edu/bitstream/2027.42/57139/1/OP703.pd

    Left atrial function and remodelling in aortic stenosis.

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    AIMS: The present study sought to determine the relationship between left atrial (LA) volume (structural changes) and LA function as assessed by strain rate imaging in patients with aortic stenosis (AS). METHODS AND RESULTS: The study consisted of a total of 64 consecutive patients with severe AS (<1 cm²) and 20 healthy control subjects. The phasic LA volumes and function (tissue Doppler-derived strain) were assessed in all patients. As compared with healthy controls, all strain-derived parameters of LA function were reduced in patients with AS. Conversely, only indexed LA passive volume (increased) (7.6 ± 3.8 vs. 10.5 ± 5.1 ml/m², P= 0.02) and LA active fraction (decreased) (43 ± 6.7 vs. 31 ± 13.3%, P< 0.001) (volume-based parameters) were significantly different between AS and controls. In AS, LA volume-derived function parameters were poorly correlated with LA strain parameters. In fact, by multivariable analysis, no LA phasic strain parameters emerged as independently associated with LA phasic volume parameters. CONCLUSIONS: In AS, changes in LA function did not parallel changes in LA size. Furthermore, the increase in LA volume does not necessarily reflect the presence of intrinsic LA dysfunctio

    Study protocol: Reporting characteristics of intervention trials of animals published in the Journal of Dairy Science in 2017

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    Objectives The scope of this cross-sectional observational study is to evaluate prevalence of reporting the 19 objective items of the REFLECT statement checklist (Sargeant et al., 2010), with the primary outcome being prevalence of sample size calculation, in clinical trials published in the Journal of Dairy Science from January to December of 2017. We will also determine risk of bias in individual studies using the Cochrane Risk of Bias 2.0 tools for individually randomized, parallel group trials; cluster randomized, parallel group trials; and individually randomized, cross-over trials (Higgins et al., 2016)
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