6,192 research outputs found

    NN interaction in a Goldstone boson exchange model

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    Adiabatic nucleon-nucleon potentials are calculated in a six-quark nonrelativistic chiral constituent quark model where the Hamiltonian contains a linear confinement and a pseudoscalar meson (Goldstone boson) exchange interaction between quarks. Calculations are performed both in a cluster model and a molecular orbital basis, through coupled channels. In both cases the potentials present an important hard core at short distances, explained through the dominance of the [51]_{FS} configuration, but do not exhibit an attractive pocket. We add a scalar meson exchange interaction and show how it can account for some middle-range attraction.Comment: 32 pages with 12 eps figures incorporated, RevTeX. Final version published in PR

    Time-based measurement of personal mite allergen bioaerosol exposure over 24 hour periods

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    © 2016 Tovey et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, colocated with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical development and clinical applications

    Prevalence of drugged drivers among non-fatal driver casualties presenting to a trauma centre in Hong Kong

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    OBJECTIVE: To investigate the prevalence and characteristics of abusive drug exposure among non-fatal motor vehicle driver casualties presenting to a designated trauma centre in Hong Kong. DESIGN: Cross-sectional study. SETTING: Designated trauma centre/regional accident and emergency department in Hong Kong. SUBJECTS: Non-fatal motor vehicle driver casualties who presented to the trauma centre from 1 January 2007 to 31 December 2007. MAIN OUTCOME MEASURES: Screening of abusive drug exposure using commercial bedside urine immunoassay kits. RESULTS: Drug screening was performed in 395 injured drivers, 10% of whom tested positive for the drugs of interest. Ketamine was the most commonly detected abusive substance (found in 45% of the subjects). A significantly higher proportion of young drivers (aged <25 years) screened positive (odds ratio=2.3; 95% confidence interval, 1.0-5.2; P=0.04), with the rate being 21%. The presence of these drugs in urine was related to the time of occurrence of the crash; those occurring between midnight and dawn revealed a trend towards a higher proportion of casualties testing drug-positive (odds ratio=2.2; 95% confidence interval, 0.9-5.3; P=0.07). There were no significant differences in the frequency of persons testing positive for the screened drugs with respect to gender, class of motor vehicle driven, or the day of the week on which the crash occurred. CONCLUSIONS: The prevalence of drugged driving among non-fatal casualties in our series of Hong Kong drivers was 10%. The frequency of such drivers testing positive for drugs was significantly higher in persons aged less than 25 years. These findings indicate a need to amend existing laws and implement on-site drug screening for suspected drugged drivers.published_or_final_versio

    Fabrication and transport critical currents of multifilamentary MgB2/Fe wires and tapes

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    Multifilamentary MgB2/Fe wires and tapes with high transport critical current densities have been fabricated using a straightforward powder-in-tube (PIT) process. After annealing, we measured transport jc values up to 1.1 * 105 A/cm2 at 4.2 K and in a field of 2 T in a MgB2/Fe square wire with 7 filaments fabricated by two-axial rolling, and up to 5 * 104 A/cm2 at 4.2 K in 1 T in a MgB2/Fe tape with 7 filaments. For higher currents these multifilamentary wires and tapes quenched due to insufficient thermal stability of filaments. Both the processing routes and deformation methods were found to be important factors for fabricating multifilamentary MgB2 wires and tapes with high transport jc values.Comment: 13 pages, 7 figure

    Malondialdehyde level and some enzymatic activities in subclinical mastitis milk

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    The purpose of this study was to evaluate the changes occurring in milk malondialdehyde (MDA) level and some enzymatic activities as a result of subclinical mastitis (SCM) in dairy cows. A total of 124 milk samples were collected from 124 lactating cows from the same herd in the period between the 2nd week after calving and the 10th week postpartum. They were classified by bacterial culture and the California mastitis test (CMT) as positive were deemed to have glands with SCM, and the periodic incidence rate of SCM was 26.6%. The most common bacterial isolates from SCM cases were Staphylococcus aureus (47%) and coagulase negative Staphylococci (CNS) (27%). The mean level of MDA and activities of lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) were significantly higher in SCM milk than in normal milk, while the mean activity of glutathione peroxidase (GPx) was significantly lower in SCM milk than in normal milk. There were no differences in the activities of superoxide dismutase (SOD) and aspartate aminotransferase (AST) between normal milk and SCM milk. Therefore, the measurement of milk MDA level and GPx, LDH and ALP activities, appears to be a suitable diagnostic method for identifying SCM in dairy cows.Key words: Subclinical mastitis, mastitis diagnostic, etiology, malonaldehyde (MDA), enzym

    Convergence and divergence in the evolution of cat skulls: temporal and spatial patterns of morphological diversity

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    Background: Studies of biological shape evolution are greatly enhanced when framed in a phylogenetic perspective. Inclusion of fossils amplifies the scope of macroevolutionary research, offers a deep-time perspective on tempo and mode of radiations, and elucidates life-trait changes. We explore the evolution of skull shape in felids (cats) through morphometric analyses of linear variables, phylogenetic comparative methods, and a new cladistic study of saber-toothed cats. Methodology/Principal Findings: A new phylogenetic analysis supports the monophyly of saber-toothed cats (Machairodontinae) exclusive of Felinae and some basal felids, but does not support the monophyly of various sabertoothed tribes and genera. We quantified skull shape variation in 34 extant and 18 extinct species using size-adjusted linear variables. These distinguish taxonomic group membership with high accuracy. Patterns of morphospace occupation are consistent with previous analyses, for example, in showing a size gradient along the primary axis of shape variation and a separation between large and small-medium cats. By combining the new phylogeny with a molecular tree of extant Felinae, we built a chronophylomorphospace (a phylogeny superimposed onto a two-dimensional morphospace through time). The evolutionary history of cats was characterized by two major episodes of morphological divergence, one marking the separation between saber-toothed and modern cats, the other marking the split between large and small-medium cats. Conclusions/Significance: Ancestors of large cats in the ‘Panthera’ lineage tend to occupy, at a much later stage, morphospace regions previously occupied by saber-toothed cats. The latter radiated out into new morphospace regions peripheral to those of extant large cats. The separation between large and small-medium cats was marked by considerable morphologically divergent trajectories early in feline evolution. A chronophylomorphospace has wider applications in reconstructing temporal transitions across two-dimensional trait spaces, can be used in ecophenotypical and functional diversity studies, and may reveal novel patterns of morphospace occupation

    A study of pentaquarks on the lattice with overlap fermions

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    We present a quenched lattice QCD calculation of spin-1/2 five-quark states with uuddsˉuudd\bar{s} quark content for both positive and negative parities. We do not observe any bound pentaquark state in these channels for either I = 0 or I =1. The states we found are consistent with KN scattering states which are checked to exhibit the expected volume dependence of the spectral weight. The results are based on overlap-fermion propagators on two lattices, 12^3 x 28 and 16^3 x 28, with the same lattice spacing of 0.2 fm, and pion mass as low as ~ 180 MeV.Comment: accepted for publication in Phys. Rev.

    Harvesting convalescent plasma for hyperimmune intravenous globulin production: a multicentre randomised double-blind controlled trial for treatment of patients with serious S-OIV H1N1 infection

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    Poster Presentations: Emerging / Infectious Diseases: abstract no. P107-Ab0089Symposium Theme: Translating Health Research into Policy and Practice for Health of the Populationpublished_or_final_versio
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