Line Shape Broadening in Surface Diffusion of Interacting Adsorbates with Quasielastic He Atom Scattering

The experimental line shape broadening observed in adsorbate diffusion on metal surfaces with increasing coverage is usually related to the nature of the adsorbate-adsorbate interaction. Here we show that this broadening can also be understood in terms of a fully stochastic model just considering two noise sources: (i) a Gaussian white noise accounting for the surface friction, and (ii) a shot noise replacing the physical adsorbate-adsorbate interaction potential. Furthermore, contrary to what could be expected, for relatively weak adsorbate-substrate interactions the opposite effect is predicted: line shapes get narrower with increasing coverage.Comment: 4 pages, 2 figures (slightly revised version

Genetic relationship of the marismeña cow with some andalusian breeds

The Marismeña breed has a large variety of coat colors, this fact could be explained by the influence of other Andalusian breeds like Pajuna, or Berrenda. The objective of this research work was to detect the influence of some different Andalusian bovine breeds into the Marismeña bovine population from Doñana National Park. For the DNA extraction blood samples were used from the races: (n=224) Marismeña (40), Berrenda en Colorado (40), Berrenda en Negro (32) y Pajuna (40); as control groups, Palmera (43) and Nelore (29). A 27 microsatellites battery applied in the European project of bovine breeds characterization was used in this work. Most of microsatellites were Hardy-Weinberg equilibrated, except Berrenda en Negro was found 11 in disequilibrium (p<0.01). The individual assignment was performed with Bayesian (Structure) method. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Marismeña breed. Thus, the Marismeña breed may not be admixture with Pajuna, Berrenda en Negro or Berrenda en Colorado.La raza Marismeña es una de las razas con el color de capa más variado, incluye desde los colores sólidos hasta los berrendos. El objetivo de este trabajo fue detectar la influencia de algunas razas andaluzas en la población bovina Marismeña del Parque Nacional de Doñana. Se utilizó sangre para la extracción de ADN de animales de las razas (n): Marismeña (40), Berrenda en Colorado (40), Berrenda en Negro (32) y Pajuna (40); se manejaron como poblaciones control la Palmera (43) y la Nelore (29). Se utilizó una batería de 27 microsatélites que fueron aplicados en el proyecto europeo de caracterización de razas bovinas. La mayoría de los microsatélites se encontraron en equilibrio Hardy-Weinberg excepto la Berrenda en Negro que tuvo 11 en desequilibrio (p<0,01). Se realizó un análisis de asignación de los individuos a su población con el programa Structure versión 2.1. El análisis bayesiano para asignación multilocus indicó que la raza Marismeña es la que esta genéticamente mejor definida. Se analizaron valores de k (número de poblaciones) de 2 a 6. Se concluye que la raza Marismeña no tiene influencia de Pajuna o de las Berrendas

Genetic characterization of the canarian sheep with microsatellites

The Canarian sheep is an autochthonous breed used for milk production. In this work 28 microsatellite markers are used to characterize this population. Samples from different breeders are collected randomly and allelic frequencies, heterozygosity and Fis has been calculated. The main conclusion is that it is an ovine breed with an elevated genetic diversity and homogeneity. This study constitutes the first step for any management strategy because it permits to know the genetic situation of the breed, to design a microsatellite panel for parentage test, to establish the genetic relationships with other ovine populations, to assign individuals to populations or traceability of derived products.Se ha caracterizado genéticamente una población de oveja Canaria, raza autóctona dedicada a la producción de leche, con 28 microsatélites de ADN. Se han calculado frecuencias alélicas, heterocigosidad y Fis. Puede concluirse que se trata de una raza ovina con elevada diversidad genética y que es genéticamente homogénea. Este estudio es básico para cualquier estrategia de gestión de la raza pues se conoce su situación genética. A partir de este punto puede abordarse el control de la genealogía con marcadores moleculares pues, con los resultados obtenidos, puede diseñarse un panel de microsatélites (8-10) para control de paternidad. También se pueden estudiar sus relaciones genéticas con otras poblaciones ovinas españolas o extranjeras, o la asignación de individuos a poblaciones o trazabilidad de productos derivados de esta raza

Quasi-elastic peak lineshapes in adsorbate diffusion on nearly flat surfaces at low coverages: the motional narrowing effect in Xe on Pt(111)

Quasi-elastic helium atom scattering measurements have provided clear evidence for a two-dimensional free gas of Xe atoms on Pt(111) at low coverages. Increasing the friction due to the surface, a gradual change of the shape of the quasi-elastic peak is predicted and analyzed for this system in terms of the so-called motional narrowing effect. The type of analysis presented here for the quasi-elastic peak should be prior to any deconvolution procedure carried out in order to better extract information from the process, e.g. diffusion coefficients and jump distributions. Moreover, this analysis also provides conditions for the free gas regime different than those reported earlier.Comment: 12 pages, 4 figures (revised version

Understanding the impact of line-of-sight in the ergodic spectral efficiency of cellular networks

In this paper we investigate the impact of lineof-sight (LoS) condition in the ergodic spectral efficiency of cellular networks. To achieve this goal, we have considered the kappa-mu shadowed model, which is a general model that provides an excellent fit to a wide set of propagation conditions. To overcome the mathematical complexity of the analysis, we have split the analysis between large and small-scale effects. Building on the proposed framework, we study a number of scenarios that range from heavily-fluctuating LoS to deterministic-LoS. Finally, we shed light on the interplay between fading severity and spectral efficiency by means of the amount of fading.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Genetic relationship of the Chiapas sheep breed with some spanish breeds

In the Southeastern part of Mexico, there are ovines descendent from Spanish ovines that were introduced in XVI century. The objective was to characterize ovine populations from Chiapas and the genetic distances with some Spanish breeds. 27 widely used microsatellites in biodiversity studies were employed in this research work. Ovines from Canary Islands were the more genetically distant from Mexicans. An algorithm inferring such admixture of genotypes of the population was used (one of de ancestors belongs to a different population). The number of inferred populations (K) was from 2 to 7 and the total number of iterations was 800000. When K=3, breeds from Chiapas were grouped, Palmera in another group and Merino, Sopravissana and Canaria in the third group. With K= 4. The breeds from Chiapas were once more grouped in a cluster, Merino and Sopravissana in a second group, Palmera and Canaria, were two independent clusters. For K=5. The breeds from Chiapas were grouped, and independent groups for the rest of breeds. With K=6 Chamula and Café remained together and with K=7 the program assigned to the breeds Chiapas, Chamula and Café in different clusters, but a remarkable influence from Chamula into Café is appreciated. The Palmera was partially divided in two clusters, showing that could exist individuals genetically different inside this population. The Borrego Chiapas has a vast individuality and genetic diversity.En el sureste de México existen ovinos que descienden de los ovinos españoles introducidos en el siglo XVI. El objetivo fue caracterizar las poblaciones ovinas de Chiapas y analizar las distancias genéticas con algunas poblaciones ovinas españolas. Se emplearon 27 microsatélites ampliamente utilizados en estudios de biodiversidad. Las ovejas de las Islas Canarias fueron las más distantes genéticamente de las de México. Se utilizó un algoritmo que infiere una mezcla de los genotipos de la población, es decir, que alguno de los ancestros pertenece a otra población. El número de poblaciones inferidas (K) fue de 2 a 7 y el número total iteraciones fue de 800000. Cuando K=2 el programa asignó en un cluster las razas Palmera y Canaria y en el otro todas las demás. Cuando K=3 se agruparon las chiapanecas, la Palmera sola y la Merino, Sopravissana y Canaria. Con K=4 se agruparon las chiapanecas en un cluster, la Merino y Sopravissana en otro y la Palmera y Canaria independientes. Con el valor de K=5, las de Chiapas se agruparon en uno y las otras cada una independiente. Con K=6 se mantuvieron unidas Chamula y Café y con K=7 el programa asignó a las razas Chiapas, Chamula y a la Café en clusters independientes, aunque se percibe una fuerte influencia de la Chamula en la Café. La Palmera quedó parcialmente dividida ente dos clusters, indicando que puede haber individuos genéticamente diferentes dentro de esta población. El Borrego Chiapas posee una gran individualidad y diversidad genéticas

A generalized Chudley-Elliott vibration-jump model in activated atom surface diffusion

Here the authors provide a generalized Chudley-Elliott expression for activated atom surface diffusion which takes into account the coupling between both low-frequency vibrational motion (namely, the frustrated translational modes) and diffusion. This expression is derived within the Gaussian approximation framework for the intermediate scattering function at low coverage. Moreover, inelastic contributions (arising from creation and annihilation processes) to the full width at half maximum of the quasi-elastic peak are also obtained.Comment: (5 pages, 2 figures; revised version

New non-unitary representations in a Dirac hydrogen atom

New non-unitary representations of the SU(2) algebra are introduced for the case of the Dirac equation with a Coulomb potential; an extra phase, needed to close the algebra, is also introduced. The new representations does not require integer or half integer labels. The set of operators defined are used to span the complete space of bound state eigenstates of the problem thus solving it in an essentially algebraic way

Quantum Zeno and anti-Zeno effects in surface diffusion of interacting adsorbates

Surface diffusion of interacting adsorbates is here analyzed within the context of two fundamental phenomena of quantum dynamics, namely the quantum Zeno effect and the anti-Zeno effect. The physical implications of these effects are introduced here in a rather simple and general manner within the framework of non-selective measurements and for two (surface) temperature regimes: high and very low (including zero temperature). The quantum intermediate scattering function describing the adsorbate diffusion process is then evaluated for flat surfaces, since it is fully analytical in this case. Finally, a generalization to corrugated surfaces is also discussed. In this regard, it is found that, considering a Markovian framework and high surface temperatures, the anti-Zeno effect has already been observed, though not recognized as such.Comment: 17 pages, 1 figur