538 research outputs found
Genetic variability and phylogenetic relationships of the autochthonous horse breed for meat production based on mitochondrial DNA
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
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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
According to previous work on magnetic monopoles, static regular solutions
are nonexistent if the vacuum expectation value of the Higgs field is
larger than a critical value , which is of the order of the
Planck mass. In order to understand the properties of monopoles for
, we investigate their dynamics numerically. If is
large enough (), a monopole expands exponentially and a
wormhole structure appears around it, regardless of coupling constants and
initial configuration. If is around , 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
Static solutions in spherical symmetry are found for gravitating global
monopoles. Regular solutions lacking a horizon are found for , where 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 is argued to have a horizon at infinity.
The failure to find static solutions for
is consistent with findings that topological inflation begins at .Comment: 4 pages, 6 figure
Mealiness assessment in apples using MRI techniques
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
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
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
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
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
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
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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