Renormalization Group Flow for Noncommutative Fermi Liquids

Some recent studies of the AdS/CFT correspondence for condensed matter systems involve the Fermi liquid theory as a boundary field theory. Adding B-flux to the boundary D-branes leads in a certain limit to the noncommutative Fermi liquid, which calls for a field theory description of its critical behavior. As a preliminary step to more general consideration, the modification of the Landau's Fermi liquid theory due to noncommutativity of spatial coordinates is studied in this paper. We carry out the renormalization of interactions at tree level and one loop in a weakly coupled fermion system in two spatial dimensions. Channels ZS, ZS' and BCS are discussed in detail. It is shown that while the Gaussian fixed point remains unchanged, the BCS instability is modified due to the space non-commutativity.Comment: 27 pages, 2 figures, section 3.2 and conclusions were change

Twisted Covariant Noncommutative Self-dual Gravity

A twisted covariant formulation of noncommutative self-dual gravity is presented. The formulation for constructing twisted noncommutative Yang-Mills theories is used. It is shown that the noncommutative torsion is solved at any order of the $\theta$-expansion in terms of the tetrad and some extra fields of the theory. In the process the first order expansion in $\theta$ for the Pleba\'nski action is explicitly obtained.Comment: 23+1 pages, no figures, corrected typos, references and Appendix B is adde

Crossing the phantom divide in an interacting generalized Chaplygin gas

Unified generalized Chaplygin gas models assuming an interaction between dark energy and dark matter fluids have been previously proposed. Following these ideas, we consider a particular relation between dark densities, which allows the possibility of a time varying equation of state for dark energy that crosses the phantom divide at a recent epoch. Moreover, these densities decay during all the evolution of the Universe, avoiding a Big Rip. We find also a scaling solution, i.e. these densities are asymptotically proportional in the future, which contributes to the solution of the coincidence problem.Comment: Improved version, 10 pages, 4 figures, References adde

Towards SDp-brane Quantization

The quantum mechanical analysis of the canonical hamiltonian description of the effective action of a SDp-brane in bosonic ten dimensional Type II supergravity in a homogeneous background is given. We find exact solutions for the corresponding quantum theory by solving the Wheeler-deWitt equation in the late-time limit of the rolling tachyon. The probability densities for several values of p are shown and their possible interpretation is discussed. In the process the effects of electromagnetic fields are also incorporated and it is shown that in this case the interpretation of tachyon regarded as ``matter clock'' is modified.Comment: 15 pages, 3 eps figures, revtex

Variation of the phenolic composition and a-glucosidase inhibition potential of seeds, soaked seeds, and sprouts of four wild forms and four varieties of common bean (Phaseolus vulgaris)

The determination of the changes in the composition of bioactive phenolic compounds of germinating seeds which accumulate high levels of these compounds could contribute to the understanding of the germination mechanism and the development of markers for the selection of plant genotypes. In the current study, the changes in the phenolic composition and a-glucosidase inhibition activity, taking place during the germination of four wild forms and four varieties of common bean (Phaseolus vulgaris L.) from Durango Mexico, were determined. A total of 66 phenolic compounds (19 phenolic acids, 18 isoflavones, 18 flavonol glycosides, 3 flavonol aglycones, 3 flavones, 2 dihydroflavonoids, 2 chalcones and one non-identified type) were found by HPLC-DAD, which were differentially accumulated by the seeds, 24 h-soaked seeds, and 4 day-sprouts of each genotype. The accumulation of the flavonol aglycones, myricetin, quercetin and kaempferol was distinctive of the wild seeds. Soaking not only caused leaching and degradation but also triggered the synthesis of new phenolic compounds whereas germination diversified the composition of isoflavones and flavonol glycosides. The seeds of all genotypes analyzed were important inhibitors of a-glucosidase, improving their potential after soaking and germination. The results suggested that the structure rather than the concentration of the flavonoids and phenolic acids determined the inhibitory potential of a-glucosidase of samples. The principal component analysis and cluster analysis revealed HPLC-DAD phenolic profiles as genotype-specific chemomarkers at any of the states (seeds, soaked seeds, and sprouts). The results have wide implications on agronomy and food quality

Size, Age, and Spatial-Temporal Distribution of Shortfin Mako in the Mexican Pacific Ocean

Abstract Basic population parameters such as age, size, and distribution have been poorly evaluated for the Shortfin Mako Isurus oxyrinchus in the Mexican Pacific Ocean. According to data collected by scientific observers on board medium-size fishing vessels during the period of 2006–2013, size as TL was obtained for 5,740 individual sharks. The range of TL was 70–362 cm for females and 71–296 cm for males. Weight (W), measured randomly from 1,409 individuals, ranged from 2 to 90 kg for females and from 2 to 80 kg for males. The weight-to-TL ratio was best fitted by the equation W = 4 × 10−5(TL)2.59 (r2 = 0.6532). No sex-specific difference was found in the weight-to-TL relationship between males and females, nor in W or TL separately. By using the inverse von Bertalanffy equation and parameters described by other authors for the same study area, we determined the age range for individuals captured on the basis of their TL. The age ranged from 0 to 39 years in females and from 0 to 21 years in males. Using a logistic model, the mean length at sexual maturity was obtained for 2,532 males (TL = 190 cm). The quarterly distribution of young of the year and 1-year-old juveniles showed that there is a tendency for these sharks to mov

Muestreo a bordo de barcos mexicanos para estimar la estructura poblacional del atún aleta amarilla (Thunnus albacaares) del Pacífico Oriental

A stratified three-stage sampling design is proposed to obtain furcal length (FL) of yellowfin tuna (Thunnus albacares) on board of Mexican purse-seine vessels in the eastern Pacific Ocean. The strata correspond to the administration regions proposed by the Interamerican Tropical Tuna Commission (IATTC) and are combined with three different sets: dolphin sets (DS), school sets (SS) and log sets (LS). In the first stage, it is obtained a random sample of the trips, over annual period. The second units (fishery sets, in each trip) are through a systematic sampling. Finally, a random sample of yellow fin tunas (third stage) is obtained in each set. This samplig design (SD) allows to estimate the average weight, total number of fishes and total number of fish by length class in the catch. The SD and their estimators were applied to the FL sample in 1997 at sea. It was observed that the average weight of the fishes in DS and SS was significantly larger than in LS (P<0.05), whereas the number of fishes by ton was higher in this last. Moreover, the size structure of fishes in DS and SS tends to values close to 100 cm, whereas in the LS the central values were about 50 cm. These are similar to those obtained by others SD in ports (Tomlinson et al., 1992). However, this SD has the advantage of including information from the bycatch and it of covering a grater zone also.Se propone un diseño de muestreo estratificado en tres estapas para obtener muestras de longitudes furcales (LF) de atún aleta amarilla (Thunnus albacares) a bordo de embarcacioes cerqueras mexicanas en el Océano Pacífico Oriental. Los estratos corresponden a las regiones administrativas propuestas por la Comisión Interamericana del Atún Tropical (CIAt), combinados con los tres tipos de lances: lances sobre delfín (LD), lances sobre cardúmenes libres (LC) y laces sobre objetos flotantes (LOF). En un año y para cada estrato, se obtiene una muestra aleatoria de viajes pesqueros (unidades primarias). Las unidades secundarias (lances pesqueros, dentro de cada viaje seleccionado) son obtenidas a través de un esquema de muestreo sistemático. Finalmente, una muestra aleatoria de atunes aleta amarilla (tercera etapa) es obtenida en cada lance. Este diseño de muestreo (DM) permite estimar el peso promedio de los atunes aleta amarilla capturados, el número total de peces de esa especie y el número por clase de longitud, para la captura. El DM y sus estimadores fueron aplicados a la muestra de atunes obtenida en los viajes de pesca realizados durante 1997. Se observó que el peso promedio de los peces en LD y LC fue significativamente mayor al peso promedio de los peces capturados en LOF (P<0.05), pero el número de peces por tonelada fue superior en este último. Además, la estructura por talla de peces en LD y en LC tinden a valores cercanos a 100 cm, mientras que en LOF los valores centrales se aproximan a los 50 cm. Estos resultados son semejantes a los obtenidos por otros DM definidos para la captura de desembarco (Tomlinson et al., 1992). Sin embargo, el diseño de muestreo propuesto tiene la ventaja de abarcar un mayor intervalo de tallas (incluyendo a los peces descartados) y cubrir una zona más amplia

Descarte y captura incidental de la flota atunera mexicana menor de 363 tm de capacidad de acarreo en 1996

Due to the importance of fishing in a responsible manner, following FAO's Code of Conduct for Responsaible Fishing, there is the need to estimate the incidental catch and discard of all fisheries worldwide. The fishing logbooks of the mexican tunaboats with less than 363 metric tons of carrying capacity were analyzed to estimate the level of tuna discards and incidental catches during 1996. Due to the absence of scientific observers aboard, direct and indirect methods were used. The tun discard estimate varied fro 190 to 230 metric tons, and the incidental catch estimate from 146 to 262 metric tons of different species or group os species. The discard estimate represents approximately 1.3 to 1.6% of total catch, and the incidental catch estimate about 1.0 to 1.8%. These levels are low compared to worldwide and other tun fisheries discard and incidental catch estimates, but the damage they cause to the populations affected are subject to further population dynamic studies.Debido a la importancia de realizar actividades pesqueras responsables, de acuerdo al Código de Conducta para l Pesca Responsable de la FAO, es de gran necesidad el contar con estimaciones de la captura incidental y descartes en todas las pesquerías a nivel mundial. En el presnte trabajo se aalizaron bitácoras de pesca de embarcaciones atuneras mexicanas menores de 363 tm de capacidad de acarreo para obtener una estimación del nivel de descarte de atunes y captura incidental en 1996. Debido  a la ausencia de observadores científicos a bordo, se utilizaron métodos directos e indirectos para las estimaciones. Se estimó un descarte de atunes con un intervalo de 190 a 230 toneladas métricas, y captura incidental con un intervalo de 146 a 262 toneladas métricas de diferentes especies o grupos de especies. El descarte representa entre el 1.3 y 1.6% de la captura total, y la captura incidental entre el 1.0 y 1.8%. Estos niveles resultan bajos comparados con los niveles mundiales y con los de otras pesquerías de túnidos, pero el daño que causan a las poblaciones está sujeto a estudios futuros sobre la dinámica poblacional de cada especie descartada o capturada incidentalmente

Determination of Lmax for Atlantic Bluefin Tuna, Thunnus thynnus (L.), from Meta-Analysis of Published and Available Biometric Data

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