f [N pi N]: from quarks to the pion derivative coupling

We study the N pi N coupling, in the framework of a QCD-inspired confining Nambu-Jona-Lasinio model. A simple relativistic confining and instantaneous quark model is reviewed. The Salpeter equation for the nucleon and the boosted pion is solved. The f [n pi n] and f[n pi Delta] couplings are calculated and they turn out to be reasonably good. The sensibility of f[n pi n] and f[n pi Delta] to confinement, chiral symmetry breaking and Lorentz invariance is briefly discussed.Comment: 30 pages in LaTex RevTex, 6 postscript figure

Repulsive Core of NN S-Wave Scattering in a Quark Model with a Condensed Vacuum

We work in a chiral invariant quark model, with a condensed vacuum, characterized by only one parameter. Bound state equations for the nucleon and Delta are solved in order to obtain an updated value of their radii and masses. Nucleon-nucleon S-Wave scattering is studied in the RGM framework both for isospin T=1 and T=0. The phase shifts are calculated and an equivalent local potential, which is consistent with K-N scattering, is derived. The result is a reasonable microscopic short range repulsion in the nucleon-nucleon interaction.Comment: 23 pages in latex revtex, 4 Postscript figure

Riesgo sísmico, geotécnico y estructural. El caso de estudio de los edificios San Jerónimo de Yuste en Bogotá

San Jerónimo de Yuste buildings are located in Bogotá, on sloping ground, in the foothills of the city. These buildings were built between 2008 and 2011 by the company BIO Construcciones, as part of a broader development project promoted by the family compensation fund Compensar. During the months of May and June 2013 the slope suffered both vertical and horizontal displacements that visibly damaged two of the buildings, which were then evacuated. This paper presents the studies conducted by the Architecture and Engineering Schools at Universidad de los Andes, in order to determine the causes that led to movement, estimate the safety factor and propose interventions at the geotechnical and structural levels which would allow the recovery of the affected buildings.El conjunto residencial San Jerónimo de Yuste se encuentra ubicado en Bogotá, en un terreno inclinado en el pie de monte de los cerros orientales de la ciudad. Fue construido entre 2008 y 2011, como parte de un proyecto de urbanización promovido por la caja de compensación familiar Compensar. Durante mayo y junio de 2013 el terreno presentó desplazamientos tanto verticales como horizontales que generaron daños visibles en las estructuras y motivaron la evacuación de dos de las seis torres que conforman el conjunto. El presente trabajo presenta los resultados de la investigación que llevaron a cabo los grupos de investigación de las facultades de Arquitectura e Ingeniería de la Universidad de los Andes para determinar las causas que condujeron al evento de desplazamiento de la estructura debidas al movimiento del terreno, estimar el coeficiente de seguridad actual y proponer intervenciones geotécnicas y estructurales que permitan recuperar la edificación

Non-alcoholic fatty liver in hereditary fructose intolerance

Background: Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation affecting >5% of the liver volume that is not explained by alcohol abuse. It is known that fructose gives rise to NAFLD and it has been recently described that the ingestion of fructose in low amounts in aldolase B deficient mice is associated with the development of fatty liver. Therefore, it is reasonable that patients with HFI (Hereditary Fructose Intolerance) present fatty liver at diagnosis, but its prevalence in patients treated and with adequate follow-up is not well documented in the literature. The aim of this study is to analyze the association between HFI and NAFLD in treated patients. Methods: A cross-sectional observational study was conducted. The population comprised 16 genetically diagnosed HFI patients aged from 3 years to 48 and in dietary treatment of fructose, sorbitol and sacarose exclusion at least for two years. Blood samples were obtained for analytical studies and anthropometric measurements of each patient were performed. Results: Patients presented a Body Mass Index (BMI) of 17.9 ± 2.9 kg/m 2 . The HOMA index and Quick index were in normal range for our population. The S-adenosyl-methionine (SAM)/S-adenosyl-L-homocysteine (SAH) ratio was increased in the patients in whom this analysis was performed. By imaging techniques it was observed that 9 of the 16 patients presented fatty liver (7 by hepatic MRI). Of these 9 patients, only 3 presented hepatomegaly. 7 of 9 patients affected by the c.448G > C mutation had fatty infiltration, of which three of them presented in addition hepatomegaly. Conclusions: There is a high prevalence of fatty liver in HFI patients and it is not related to obesity and insulin resistance. The diagnosis of fatty liver in HFI patients and, above all, the identification of new therapeutic approaches, can positively impact the quality of life of these patients

Optimal light harvesting structures at optical and infrared frequencies

One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure

A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS

We introduce coupled channels of Bethe-Salpeter mesons both in the boundstate equation for mesons and in the mass gap equation for chiral symmetry. Consistency is insured by the Ward Identities for axial currents, which preserve the Goldstone boson nature of the pion and prevents a systematic shift of the hadron spectrum. We study the decay of a scalar meson coupled to a pair of pseudoscalars. We also show that coupled channels reduce the breaking of chiral symmetry, with the same Feynman diagrams that appear in the coupling of a scalar meson to a pair of pseudoscalar mesons. Exact calculations are performed in a particular confining quark model, where we find that the groundstate $I=0, ^3P_0 q \bar q$ meson is the f_0(980) with a partial decay width of 40MeV. We also find a 30% reduction of the chiral condensate due to coupled channels.Comment: 17 pages, Revtex, 8 eps figures, and several eps diagrams in equation

A Non-perturbative Treatment of Heavy Quarks and Mesons

A formalism for studying heavy quarks in terms of model Dyson-Schwinger equations is developed. The formalism is the natural extension of a technique which has proved successful in a number of studies of light hadron physics. The dressed heavy quark propagator, calculated to leading order in the inverse quark mass, is incorporated in a treatment of mesons consisting of a heavy quark and light antiquark via the ladder approximation Bethe-Salpeter equation. In the limit of infinite heavy quark mass the model is found to respect the spectrum degeneracies present in Heavy Quark Effective Theory. An exploratory numerical analysis of a simple form of the model is carried out to assess its viability for studying $D$ and $B$ mesons.Comment: 20 pages, 3 postscript figures, alterations mainly rewriting of Section VI (Numerical calculations

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Cloning and characterization of XiR1, a locus responsible for dagger nematode resistance in grape

The dagger nematode, Xiphinemaindex, feeds aggressively on grape roots and in the process, vectors grapevine fanleaf virus (GFLV) leading to the severe viral disease known as fanleaf degeneration. Resistance to X. index and GFLV has been the key objective of grape rootstock breeding programs. A previous study found that resistance to X. index derived from Vitis arizonica was largely controlled by a major quantitative trait locus, XiR1 (X. index Resistance 1), located on chromosome 19. The study presented here develops high-resolution genetic and physical maps in an effort to identify the XiR1 gene(s). The mapping was carried out with 1,375 genotypes in three populations derived from D8909-15, a resistant selection from a cross of V. rupestris A. de Serres (susceptible) × V. arizonica b42-26 (resistant). Resistance to X. index was evaluated on 99 informative recombinants that were identified by screening the three populations with two markers flanking the XiR1 locus. The high-resolution genetic map of XiR1 was primarily constructed with seven DNA markers developed in this study. Physical mapping of XiR1 was accomplished by screening three bacterial artificial chromosome (BAC) libraries constructed from D8909-15, V. vinifera Cabernet Sauvignon and V. arizonica b42-26. A total of 32 BAC clones were identified and the XiR1 locus was delineated within a 115 kb region. Sequence analysis of three BAC clones identified putative nucleotide binding/leucine-rich repeat (NB-LRR) genes. This is the first report of a closely linked major gene locus responsible for ectoparasitic nematode resistance. The markers developed from this study are being used to expedite the breeding of resistant grape rootstocks