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Search Results: 1 - 10 of 369084 matches for " L. G. Garcia "
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Neutron beta decay and the current determination of Vud
A. Garcia,J. L. Garcia-Luna,G. Lopez Castro
Physics , 2000, DOI: 10.1016/S0370-2693(01)00051-X
Abstract: Measurements of neutron beta decay observables required to determine $|V_{ud}|$ are reaching the 0.1% accuracy. In this paper we review the calculation of the decay rate of this process, discuss its relevant uncertainties, and obtain an expression that is precise at the $10^{-4}$ level. Our analysis clearly shows the necessity of measurements of $\lambda$, the ratio of axial/vector couplings. The current situation in neutron beta decay is that one cannot yet quote a single consistent value for $|V_{ud}|$ from it. We also discuss the region of parameter space in the $|V_{ud}|$--$\lambda$ plane where new physics effects should lie, if they contribute to neutron beta decay.
Spatial birth and death processes as solutions of stochastic equations
Nancy L. Garcia,Thomas G. Kurtz
Mathematics , 2006,
Abstract: Spatial birth and death processes are obtained as solutions of a system of stochastic equations. The processes are required to be locally finite, but may involve an infinite population over the full (noncompact) type space. Conditions are given for existence and uniqueness of such solutions, and for temporal and spatial ergodicity. For birth and death processes with constant death rate, a sub-criticality condition on the birth rate implies that the process is ergodic and converges exponentially fast to the stationary distribution.
Sensory Perception of Food and Insulin-Like Signals Influence Seizure Susceptibility
Todd R. Gruninger,Daisy G. Gualberto,L. Rene Garcia
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000117
Abstract: Food deprivation is known to affect physiology and behavior. Changes that occur could be the result of the organism's monitoring of internal and external nutrient availability. In C. elegans, male mating is dependent on food availability; food-deprived males mate with lower efficiency compared to their well-fed counterparts, suggesting that the mating circuit is repressed in low-food environments. This behavioral response could be mediated by sensory neurons exposed to the environment or by internal metabolic cues. We demonstrated that food-deprivation negatively regulates sex-muscle excitability through the activity of chemosensory neurons and insulin-like signaling. Specifically, we found that the repressive effects of food deprivation on the mating circuit can be partially blocked by placing males on inedible food, E. coli that can be sensed but not eaten. We determined that the olfactory AWC neurons actively suppress sex-muscle excitability in response to food deprivation. In addition, we demonstrated that loss of insulin-like receptor (DAF-2) signaling in the sex muscles blocks the ability of food deprivation to suppress the mating circuit. During low-food conditions, we propose that increased activity by specific olfactory neurons (AWCs) leads to the release of neuroendocrine signals, including insulin-like ligands. Insulin-like receptor signaling in the sex muscles then reduces cell excitability via activation of downstream molecules, including PLC-γ and CaMKII.
Patterns and predictors of treatment initiation and completion in patients with chronic hepatitis C virus infection
Clark BT, Garcia-Tsao G, Fraenkel L
Patient Preference and Adherence , 2012, DOI: http://dx.doi.org/10.2147/PPA.S30111
Abstract: tterns and predictors of treatment initiation and completion in patients with chronic hepatitis C virus infection Original Research (2160) Total Article Views Authors: Clark BT, Garcia-Tsao G, Fraenkel L Published Date April 2012 Volume 2012:6 Pages 285 - 295 DOI: http://dx.doi.org/10.2147/PPA.S30111 Received: 22 January 2012 Accepted: 07 February 2012 Published: 04 April 2012 Brian T Clark1,2, Guadalupe Garcia-Tsao1,2, Liana Fraenkel1,2 1Veterans Administration, Connecticut Healthcare System, West Haven, 2Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA Objectives: Guidelines for hepatitis C (HCV) strongly recommend antiviral treatment for patients with more severe liver disease given their increased risk of developing cirrhosis and other liver-related complications. Despite the proven benefits of therapy, 70%–88% of patients chronically infected with HCV do not undergo treatment. The goal of this paper is to describe patterns of treatment initiation among patients with both mild and severe disease and to assess the factors that are associated with treatment initiation and completion. Methods: Subjects completed previously validated questionnaires to ascertain sociodemographic characteristics, choice predisposition, and clinical characteristics prior to meeting with the hepatologist to discuss treatment initiation and were followed for 12 months. We examined the association between patient characteristics and treatment patterns controlling for liver disease severity. Results: Of the 148 eligible subjects entered into our study, 55 (37%) initiated treatment during the 12-month follow-up period. Of the 86 subjects with severe liver disease, 43 (50%) initiated treatment. Financial barriers and geographic access to care were the most common reasons for treatment deferral. Of the 55 patients initiating treatment, 24 (44%) discontinued treatment, with intolerance of side effects being the most common reason for discontinuation. After adjusting for liver disease severity, patient choice predisposition (prior to discussion with their provider) was strongly associated with initiation of treatment, while sociodemographic characteristics were not. Conclusion: Treatment initiation did align with current recommendations (patients with severe disease were more likely to initiate treatment), however, rates of treatment initiation and completion were low. Patient choice predisposition is the strongest predictor of treatment initiation, independent of disease severity. Improving individualized treatment outcomes for patients with chronic HCV requires efforts at identifying patients’ choice predisposition, and improving access for those wishing to initiate therapy.
Patterns and predictors of treatment initiation and completion in patients with chronic hepatitis C virus infection
Clark BT,Garcia-Tsao G,Fraenkel L
Patient Preference and Adherence , 2012,
Abstract: Brian T Clark1,2, Guadalupe Garcia-Tsao1,2, Liana Fraenkel1,21Veterans Administration, Connecticut Healthcare System, West Haven, 2Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USAObjectives: Guidelines for hepatitis C (HCV) strongly recommend antiviral treatment for patients with more severe liver disease given their increased risk of developing cirrhosis and other liver-related complications. Despite the proven benefits of therapy, 70%–88% of patients chronically infected with HCV do not undergo treatment. The goal of this paper is to describe patterns of treatment initiation among patients with both mild and severe disease and to assess the factors that are associated with treatment initiation and completion.Methods: Subjects completed previously validated questionnaires to ascertain sociodemographic characteristics, choice predisposition, and clinical characteristics prior to meeting with the hepatologist to discuss treatment initiation and were followed for 12 months. We examined the association between patient characteristics and treatment patterns controlling for liver disease severity.Results: Of the 148 eligible subjects entered into our study, 55 (37%) initiated treatment during the 12-month follow-up period. Of the 86 subjects with severe liver disease, 43 (50%) initiated treatment. Financial barriers and geographic access to care were the most common reasons for treatment deferral. Of the 55 patients initiating treatment, 24 (44%) discontinued treatment, with intolerance of side effects being the most common reason for discontinuation. After adjusting for liver disease severity, patient choice predisposition (prior to discussion with their provider) was strongly associated with initiation of treatment, while sociodemographic characteristics were not.Conclusion: Treatment initiation did align with current recommendations (patients with severe disease were more likely to initiate treatment), however, rates of treatment initiation and completion were low. Patient choice predisposition is the strongest predictor of treatment initiation, independent of disease severity. Improving individualized treatment outcomes for patients with chronic HCV requires efforts at identifying patients’ choice predisposition, and improving access for those wishing to initiate therapy.Keywords: barriers, access, preferences, utilization, adverse events
Tratamiento físico y químico del suelo para el control Del marchitamiento vascular del clavel causado por el Hongo fusariumoxysporumf. Sp. Dianthi
Garcia David L.,Arbeláez Mario G.,Arbeláez German
Agronomía Colombiana , 1995,
Abstract: Los problemas fitosanitarios constituyen uno de los aspectos más importantes en el cultivo del clavel en Colombia, destacándose, entre ellos, el marchitamiento vascular del clavel, causado por el hongo F. oxysporum f.sp. dianthi. Con el propósito de avanzar en el manejo de dicha enfermedad. Se realizaron dos ensayos en dos fincas productoras de flores en la Sabana de Bogotá, comparando tratamientos físicos y químicos al suelo antes de la siembra. En el primer experimento efectuado con diferentes variedades de clavel estándar, se comprar el fumigante 1.3-0 Cloropicrina frente a la aplicación de vapor de agua. Los dos tratamientos fueren igualmente eficientes en la disminución de la incidencia de la enfermedad en todas las variedades evaluadas; de igual manera no se encontraron diferencias en cuanto a la reducción de la población del hongo en el suelo. Altura de las plantas y la producción y la calidad de las flores. En el segundo experimento, donde se evaluaron diferentes variedades de clavel miniatura, se compara la efectividad del fumigante 1.3-0 Cloropicrina frente al fumigante Dazomet. EI tratamiento al suelo con el fumigante 1,3-0 Cloropicrina fue más eficiente que el fumigante Dazomet en la reducción de la incidencia de la enfermedad y de la población del hongo en el suelo. En el desarrollo de las plantas y en la producción y la calidad de las flores.
Survival and Nonescape Probabilities for Resonant and Nonresonant Decay
G. Garcia-Calderon,J. L. Mateos,M. Moshinsky
Physics , 1996, DOI: 10.1006/aphy.1996.0078
Abstract: In this paper we study the time evolution of the decay process for a particle confined initially in a finite region of space, extending our analysis given recently (Phys. Rev. Lett. 74, 337 (1995)). For this purpose, we solve exactly the time-dependent Schroedinger equation for a finite-range potential. We calculate and compare two quantities: (i) the survival probability S(t), i.e., the probability that the particle is in the initial state after a time t; and (ii) the nonescape probability P(t), i.e., the probability that the particle remains confined inside the potential region after a time t. We analyze in detail the resonant and nonresonant decay. In the former case, after a very short time, S(t) and P(t) decay exponentially, but for very long times they decay as a power law, albeit with different exponents. For the nonresonant case we obtain that both quantities differ initially. However, independently of the resonant and nonresonant character of the initial state we always find a transition to the ground state of the system which indicates a process of ``loss of memory'' in the decay.
Reply to the Comment on "Resonant Spectra and the Time Evolution of the Survival and Nonescape Probabilities"
G. Garcia-Calderon,J. L. Mateos,M. Moshinsky
Physics , 1998, DOI: 10.1103/PhysRevLett.80.4354
Abstract: In our paper [Phys. Rev. Lett. 74, 337 (1995)], we derived an exact expression for the survival and nonescape probabilities as an expansion in terms of resonant states. It was shown that these quantities exhibit at long times a different behavior. Although both decay as a power law, they have different exponents. In this paper we show that, contrary to the claim in the Comment of R. M. Cavalcanti (quant-ph/9704023), the nonescape probability decay for long times as an inverse power law.
The Moduli and Gravitino (non)-Problems in Models with Strongly Stabilized Moduli
Jason L. Evans,Marcos A. G. Garcia,Keith A. Olive
Physics , 2013, DOI: 10.1088/1475-7516/2014/03/022
Abstract: In gravity mediated models and in particular in models with strongly stabilized moduli, there is a natural hierarchy between gaugino masses, the gravitino mass and moduli masses: $m_{1/2} \ll m_{3/2} \ll m_{\phi}$. Given this hierarchy, we show that 1) moduli problems associated with excess entropy production from moduli decay and 2) problems associated with moduli/gravitino decays to neutralinos are non-existent. Placed in an inflationary context, we show that the amplitude of moduli oscillations are severely limited by strong stabilization. Moduli oscillations may then never come to dominate the energy density of the Universe. As a consequence, moduli decay to gravitinos and their subsequent decay to neutralinos need not overpopulate the cold dark matter density.
Certainty relations between local and nonlocal observables
R. Garcia Diaz,J. L. Romero,G. Bjork,M. Bourennane
Physics , 2005, DOI: 10.1088/1367-2630/7/1/256
Abstract: We demonstrate that for an arbitrary number of identical particles, each defined on a Hilbert-space of arbitrary dimension, there exists a whole ladder of relations of complementarity between local, and every conceivable kind of joint (or nonlocal) measurements. E.g., the more accurate we can know (by a measurement) some joint property of three qubits (projecting the state onto a tripartite entangled state), the less accurate some other property, local to the three qubits, become. We also show that the corresponding complementarity relations are particularly tight for particles defined on prime dimensional Hilbert spaces.
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