1,107 research outputs found

    Si(Li) position sensitive detector

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    A position sensitive detector was made using the lithium diffused layer of a lithium-drifted-silicon detector as the uniform resistive layer. An expression is derived for estimating the resistance from the thickness of the lithium layer. Expressions for the noise and ballistic deficit for single differentiation-double integration pulse shaping are presented. Room temperature data for a 1 Mev proton beam on a 45 mm long detector shows that the linearity is better than .05% and that the position resolution is 1.06 + or - .05 mm

    Three-body bound states with zero-range interaction in the Bethe-Salpeter approach

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    The Bethe-Salpeter equation for three bosons with zero-range interaction is solved for the first time. For comparison the light-front equation is also solved. The input is the two-body scattering length and the outputs are the three-body binding energies, Bethe-Salpeter amplitudes and light-front wave functions. Three different regimes are analyzed: ({\it i}) For weak enough two-body interaction the three-body system is unbound. ({\it ii}) For stronger two-body interaction a three-body bound state appears. It provides an interesting example of a deeply bound Borromean system. ({\it iii}) For even stronger two-body interaction this state becomes unphysical with a negative mass squared. However, another physical (excited) state appears, found previously in light-front calculations. The Bethe-Salpeter approach implicitly incorporates three-body forces of relativistic origin, which are attractive and increase the binding energy.Comment: 13 pages, 7 figure

    Veterinary use of bacteriophage therapy in intensively-reared livestock

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    Zoonoses are infectious diseases transmitted directly or indirectly between animals and humans. Several important zoonotic pathogens colonize farm animals asymptomatically, which may lead to contamination of the food chain and public health hazards. Moreover, routine sampling of carcasses at retail by government authorities over the past 20 years suggests the prevalence of antibiotic resistance in foodborne pathogens has increased. If this continues, antibiotics may be ineffective against such pathogens in the future and alternative approaches, such as phage therapy, may be necessary. Intensive livestock farming is the only realistic way of meeting the demand for meat from an increasing global population and growth in middle class consumers in developing countries, particularly in Asia. This review elaborates on the use of phages to control zoonotic pathogens in intensively-reared livestock (poultry and pigs)

    Bound state structure and electromagnetic form factor beyond the ladder approximation

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    We investigate the response of the bound state structure of a two-boson system, within a Yukawa model with a scalar boson exchange, to the inclusion of the cross-ladder contribution to the ladder kernel of the Bethe-Salpeter equation. The equation is solved by means of the Nakanishi integral representation and light-front projection. The valence light-front wave function and the elastic electromagnetic form factor beyond the impulse approximation, with the inclusion of the two-body current, generated by the cross-ladder kernel, are computed. The valence wave function and electromagnetic form factor, considering both ladder and ladder plus cross-ladder kernels, are studied in detail. Their asymptotic forms are found to be quite independent of the inclusion of the cross-ladder kernel, for a given binding energy. The asymptotic decrease of form factor agrees with the counting rules. This analysis can be generalized to fermionic systems, with a wide application in the study of the meson structure.Comment: 19 pages, 6 figures, submitted to Phys. Lett.

    Fermion dynamics in torsion theories

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    In this work we have studied the non-geodesical behaviour of particles with spin 1/2 in Poincar\'e gauge theories of gravity, via the WKB method and the Mathisson-Papapetrou equation. We have analysed the relation between the two approaches and we have argued the different advantages associated with the WKB approximation. Within this approach, we have calculated the trajectories in a particular Poincar\'e gauge theory, discussing the viability of measuring such a motion.Comment: 17 pages, 2 figures, minor changes, conclusions unchanged. It matches the version published in JCA

    Intervenciones en el espacio urbano. Estaciones de Vila do Conde y Póvoa de Varzim

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    Intervenciones en el espacio rural. Estaciones de Vilar do Pinheriro, Modivas Sul y Mindelo

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    Chromosome 1p13 genetic variants antagonize the risk of myocardial infarction associated with high ApoB serum levels

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    PMCID: PMC3480949This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
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