538 research outputs found

    Genetic variability and phylogenetic relationships of the autochthonous horse breed for meat production based on mitochondrial DNA

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    Publicado en el año 2008 en: Revista ITEA, 104 (2), 283-289. http://www.aida-itea.org/index.php/revista/contenidos?idArt=85&lang=esp Webs desde donde descargar las ponencias: http://acteon.webs.upv.es/ Web del congreso: http://www.uco.es/genetica/MERAGEM/xivreunion.htmSe han estudiado la variabilidad y relaciones genéticas de las cuatro poblaciones equinas de aptitud cárnica de España de protección especial (41 muestras) (Burguete (BUR): 10, Jaca Navarra (JAC): 11, Hispano Bretón (HB): 10 y Agrupación Hipermétrica del Pirineo (AHP): 10) a través del estudio del ADN mitocondrial (ADNmt). Se han encontrado 15 haplotipos en las 4 razas analizadas determinados por la existencia de 19 posiciones polimórficas de las cuales 18 han sido posiciones informativas parsimoniosas y 1 no informativa (singleton). La diversidad haplotípica (Hd) ha oscilado entre 0,758 del AHP y 0,993 del BUR siendo el valor medio de todas las razas de de 0,929 (SD = 0,016). La raza JAC ha presentado el mayor valor de diversidad nucleotídica (0,023). Casi la totalidad de los haplotipos encontrados los han compartido las razas analizadas excepto el haplotipo 8 que sólo lo ha presentado la AHP, el haplotipo 10 la raza BUR, los haplotipos 13 y 14 el HB y el haplotipo 15 la raza JAC. No se ha encontrado un agrupamiento claro de las poblaciones analizadas, lo que confirma los múltiples orígenes maternos previamente indicado por varios autores. No obstante, al haberse encontrado haplotipos específicos en las 4 poblaciones analizadas se deben tenerlos en cuenta a la hora de llevar a cabo los planes de conservación.Genetic variability and phylogenetic relationships of the autochthonous horse breed for meat production based on mitochondrial DNA We have studied the genetic variability and relationships of four endangered Spanish equine populations for meat production using mitochondrial DNA (mtDNA) (41 horses, 30 of them belong to Burguete (BUR), Hispano Bretón (HB) and Agrupación Hipermétrica del Pirineo (AHP) populations and the other 11 samples belong to Jaca Navarra (JAC) breed. Fifteen haplotypes were found and 19 polomorphic sites were detected, eighteen of them were parsimony informative sites and the other one was a singleton. Haplotipic diversity (Hd) ranged from 0.758 of AHP to 0.993 of BUR breed. The average Hd value was 0.929 (SD = 0.016). The JAC breed presented the highest nucleotide diversity value (0.023). Most of haplotypes found have been shared by the four horse populations except haplotype 8 that only was presented by AHP populaton, haplotype 10 by BUR, the haplotypes 13 and 14 by HB and haplotype 15 by JAC breed. A clear group of horses belong to the same population were not shown. These results confirm the multiple maternal origin previously shown by other authors. However we have found haplotypes specific of each breed that is important to take in account in their conservation programmes

    Dynamics of Gravitating Magnetic Monopoles

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    According to previous work on magnetic monopoles, static regular solutions are nonexistent if the vacuum expectation value of the Higgs field η\eta is larger than a critical value ηcr\eta_{{\rm cr}}, which is of the order of the Planck mass. In order to understand the properties of monopoles for η>ηcr\eta>\eta_{{\rm cr}}, we investigate their dynamics numerically. If η\eta is large enough (ηcr\gg\eta_{{\rm cr}}), a monopole expands exponentially and a wormhole structure appears around it, regardless of coupling constants and initial configuration. If η\eta is around ηcr\eta_{{\rm cr}}, there are three types of solutions, depending on coupling constants and initial configuration: a monopole either expands as stated above, collapses into a black hole, or comes to take a stable configuration.Comment: 11 pages, revtex, postscript figures; results for various initial conditions are added; to appear in Phys. Rev.

    Static Gravitational Global Monopoles

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    Static solutions in spherical symmetry are found for gravitating global monopoles. Regular solutions lacking a horizon are found for η<1/8π\eta < 1/\sqrt{8\pi}, where η\eta is the scale of symmetry breaking. Apparently regular solutions with a horizon are found for 1/\sqrt{8\pi} \le \eta \alt \sqrt{3/8\pi}. Though they have a horizon, they are not Schwarzschild. The solution for η=1/8π\eta = 1/\sqrt{8\pi} is argued to have a horizon at infinity. The failure to find static solutions for η>3/8π0.3455\eta > \sqrt{3/8\pi} \approx 0.3455 is consistent with findings that topological inflation begins at η0.33\eta \approx 0.33.Comment: 4 pages, 6 figure

    Mealiness assessment in apples using MRI techniques

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    Small samples of Top Red apples stored 6 months under controlled atmosphere (expected to be non-mealy) and 2°C (expected to be mealy) have been used for MRI imaging. Multi-slice-multi-echo magnetic resonance images (64*64 pixels) have been recorded with a 8 ms echo time. Three out of four apples corresponding to the sample maintained under controlled atmosphere did not developed mealiness while three out of four fruits corresponding to the sample stored at 2°C became mealy after 6 months of storage. The minimum T2 values obtained for the mealy apples show to be significantly lower (F = 13.21) when compared with non-mealy apples pointing that a more desegregated structure and a lower juiciness content leads to lower T2 signal. Also, there is a significant linear correlation (r = −0.76) between the number of pixels with a T2 value below 35 ms within a fruit image and the deformation parameter registered during the Magness–Taylor firmness test. Finally, all T2 maps of mealy apples show a regional variation of contrast which is not shown for non-mealy apples. Significant differences (F = 19.43) between mealy and non-mealy apples are found in the histograms of the T2 maps as mealy apples show a skew histogram combined with a “tail” in their high T2 extreme which is not shown in the histograms of non-mealy apples. These histogram features are also shown for an apple showing internal breakdown indicating that in mealy apples there is a differential water movement that may precede internal breakdown

    Quasi-Black Holes from Extremal Charged Dust

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    One can construct families of static solutions that can be viewed as interpolating between nonsingular spacetimes and those containing black holes. Although everywhere nonsingular, these solutions come arbitrarily close to having a horizon. To an observer in the exterior region, it becomes increasingly difficulty to distinguish these from a true black hole as the critical limiting solution is approached. In this paper we use the Majumdar-Papapetrou formalism to construct such quasi-black hole solutions from extremal charged dust. We study the gravitational properties of these solutions, comparing them with the the quasi-black hole solutions based on magnetic monopoles. As in the latter case, we find that solutions can be constructed with or without hair.Comment: 18 page

    Charge dynamics in the Mott insulating phase of the ionic Hubbard model

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    We extend to charge and bond operators the transformation that maps the ionic Hubbard model at half filling onto an effective spin Hamiltonian. Using these operators we calculate the amplitude of the charge density wave in different dimensions. In one dimension, the charge-charge correlations at large distance d decay as 1/(d^3 ln^{3/2}d), in spite of the presence of a charge gap, as a consequence of remaining charge-spin coupling. Bond-bond correlations decay as (-1)^d 1/(d ln^{3/2}d) as in the usual Hubbard model.Comment: 4 pages, no figures, submitted to Phys. Rev. B printing errors corrected and some clarifications adde

    Confinement Effects in Antiferromagnets

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    Phase equilibrium in confined Ising antiferromagnets was studied as a function of the coupling (v) and a magnetic field (h) at the surfaces, in the presence of an external field H. The ground state properties were calculated exactly for symmetric boundary conditions and nearest-neighbor interactions, and a full zero-temperature phase diagram in the plane v-h was obtained for films with symmetry-preserving surface orientations. The ground-state analysis was extended to the H-T plane using a cluster-variation free energy. The study of the finite-T properties (as a function of v and h) reveals the close interdependence between the surface and finite-size effects and, together with the ground-state phase diagram, provides an integral picture of the confinement in anisotropic antiferromagnets with surfaces that preserve the symmetry of the order parameter.Comment: 10 pages, 8 figures, Accepted in Phys. Rev.

    Mealiness assessment in apples and peaches using MRI techniques

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    Mealiness (woolliness in peaches) is a negative attribute of sensory texture that combines the sensation of a desegregated tissue with the sensation of lack of juiciness. In this study, 24 apples cv. Top Red and 8 peaches cv. Maycrest, submitted to 3 and 2 different storage conditions respectively have been tested by mechanical and MRI techniques to assess mealiness. With this study, the results obtained on apples in a previous work have been validated using mathematical features from the histograms of the T2 maps: more skewed and the presence of a tail in mealy apples, similar to internal breakdown. In peaches, MRI techniques can also be used to identify woolly fruits. Not all the changes found in the histograms of woolly peaches are similar from those observed in mealy apples pointing to a different underlying physiological change in both disorder

    Polar Perturbations of Self-gravitating Supermassive Global Monopoles

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    Spontaneous global symmetry breaking of O(3) scalar field gives rise to point-like topological defects, global monopoles. By taking into account self-gravity,the qualitative feature of the global monopole solutions depends on the vacuum expectation value v of the scalar field. When v < sqrt{1 / 8 pi}, there are global monopole solutions which have a deficit solid angle defined at infinity. When sqrt{1 / 8 pi} <= v < sqrt{3 / 8 pi}, there are global monopole solutions with the cosmological horizon, which we call the supermassive global monopole. When v >= sqrt{3 / 8 pi}, there is no nontrivial solution. It was shown that all of these solutions are stable against the spherical perturbations. In addition to the global monopole solutions, the de Sitter solutions exist for any value of v. They are stable against the spherical perturbations when v sqrt{3 / 8 pi}. We study polar perturbations of these solutions and find that all self-gravitating global monopoles are stable even against polar perturbations, independently of the existence of the cosmological horizon, while the de Sitter solutions are always unstable.Comment: 10 pages, 6 figures, corrected some type mistakes (already corrected in PRD version

    Cosmic Strings in the Abelian Higgs Model with Conformal Coupling to Gravity

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    Cosmic string solutions of the abelian Higgs model with conformal coupling to gravity are shown to exist. The main characteristics of the solutions are presented and the differences with respect to the minimally coupled case are studied. An important difference is the absence of Bogomolnyi cosmic string solutions for conformal coupling. Several new features of the abelian Higgs cosmic strings of both types are discussed. The most interesting is perhaps a relation between the angular deficit and the central magnetic field which is bounded by a critical value.Comment: 22 pages, 10 figures; to appear in Phys. Rev.
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