47,813 research outputs found

    Relativistic Effects of Mixed Vector-Scalar-Pseudoscalar Potentials for Fermions in 1+1 Dimensions

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    The problem of fermions in the presence of a pseudoscalar plus a mixing of vector and scalar potentials which have equal or opposite signs is investigated. We explore all the possible signs of the potentials and discuss their bound-state solutions for fermions and antifermions. The cases of mixed vector and scalar P\"{o}schl-Teller-like and pseudoscalar kink-like potentials, already analyzed in previous works, are obtained as particular cases

    Unified Treatment of Mixed Vector-Scalar Screened Coulomb Potentials for Fermions

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    The problem of a fermion subject to a general mixing of vector and scalar screened Coulomb potentials in a two-dimensional world is analyzed and quantization conditions are found.Comment: 7 page

    New solutions of the D-dimensional Klein-Gordon equation via mapping onto the nonrelativistic one-dimensional Morse potential

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    New exact analytical bound-state solutions of the D-dimensional Klein-Gordon equation for a large set of couplings and potential functions are obtained via mapping onto the nonrelativistic bound-state solutions of the one-dimensional generalized Morse potential. The eigenfunctions are expressed in terms of generalized Laguerre polynomials, and the eigenenergies are expressed in terms of solutions of irrational equations at the worst. Several analytical results found in the literature, including the so-called Klein-Gordon oscillator, are obtained as particular cases of this unified approac

    Sheep Grazing Patterns for Better Land Management: Adjusting GPS Tracking Protocol

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    Small ruminant livestock systems in northeast Portugal are an extensive activity based on daily grazing paths across the landscape. The flocks use multiple patches of multiple land cover types in different ways throughout the year. Shepherd and flock interactions determine the resting and feeding spots utilized by sheep and goats according to the biotic and abiotic conditions. Information about the herding home range is central to managing the land use and vegetation cover and optimizing sheep and goats\u27 productivity in traditional systems. This study\u27s main objective is to contribute to calibrate a shepherding GPS protocol to monitor sheep flocks based on fieldwork in Vimieiro (Mirandela) on a protected area of the European Natura 2000 network. We answer two farmers\u27 and breeders\u27 requests for using GPS collars to monitor the landscape usage by sheep: (1) How closely do collared sheep remain within the flock? (2) How do the collars perform on different logging frequencies to estimate patch occupancy? We analyzed the grazing paths based on three collars\u27 5-minute GPS positions from winter to summer solstices. We investigated the differences in extent, duration, and frequency data of each collar throughout the season change based on spatial regressions. Results show no significant differences among the three collars ranges. It also indicates that positions collected every 15 and 30 minutes could be adequate. It means that a flock monitoring low cost can be generalized, providing accurate information to manage the pastoral territory and increase the small ruminant\u27s productivit

    On Duffin-Kemmer-Petiau particles with a mixed minimal-nonminimal vector coupling and the nondegenerate bound states for the one-dimensional inversely linear background

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    The problem of spin-0 and spin-1 bosons in the background of a general mixing of minimal and nonminimal vector inversely linear potentials is explored in a unified way in the context of the Duffin-Kemmer-Petiau theory. It is shown that spin-0 and spin-1 bosons behave effectively in the same way. An orthogonality criterion is set up and it is used to determine uniquely the set of solutions as well as to show that even-parity solutions do not exist.Comment: 10 page

    Tritium clouds environmental impact in air into the Western Mediterranean Basin evaluation

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    The paper considers short-term releases of tritium (mainly but not only tritium hydride (HT)) to the atmosphere from a potential ITER-like fusion reactor located in the Mediterranean Basin and explores if the short range legal exposure limits are exceeded (both locally and downwind). For this, a coupled Lagrangian ECMWF/FLEXPART model has been used to follow real time releases of tritium. This tool was analyzed for nominal tritium operational conditions under selected incidental conditions to determine resultant local and Western Mediterranean effects, together with hourly observations of wind, to provide a short-range approximation of tritium cloud behavior. Since our results cannot be compared with radiological station measurements of tritium in air, we use the NORMTRI Gaussian model. We demonstrate an overestimation of the sequence of tritium concentrations in the atmosphere, close to the reactor, estimated with this model when compared with ECMWF/FLEXPART results. A Gaussian “mesoscale” qualification tool has been used to validate the ECMWF/FLEXPART for winter 2010/spring 2011 with a database of the HT plumes. It is considered that NORMTRI allows evaluation of tritium-in-air-plume patterns and its contribution to doses

    Bound states of bosons and fermions in a mixed vector-scalar coupling with unequal shapes for the potentials

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    The Klein-Gordon and the Dirac equations with vector and scalar potentials are investigated under a more general condition, Vv+Vs=constantV_{v}+V_{s}= \mathrm{constant}. These intrinsically relativistic and isospectral problems are solved in a case of squared hyperbolic potential functions and bound states for either particles or antiparticles are found. The eigenvalues and eigenfuntions are discussed in some detail and the effective Compton wavelength is revealed to be an important physical quantity. It is revealed that a boson is better localized than a fermion when they have the same mass and are subjected to the same potentials.Comment: 3 figure
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