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Search Results: 1 - 10 of 731453 matches for " A. M. Martínez-Argüello "
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Random matrix study for a three-terminal chaotic device
A. M. Martínez-Argüello,E. Casta?o,M. Martínez-Mares
Physics , 2014, DOI: 10.1063/1.4862416
Abstract: We perform a study based on a random-matrix theory simulation for a three-terminal device, consisting of chaotic cavities on each terminal. We analyze the voltage drop along one wire with two chaotic mesoscopic cavities, connected by a perfect conductor, or waveguide, with one open mode. This is done by means of a probe, which also consists of a chaotic cavity that measure the voltage in different configurations. Our results show significant differences with respect to the disordered case, previously considered in the literature.
Wave systems with direct processes and localized losses or gains: the non-unitary Poisson kernel
A. M. Martínez-Argüello,R. A. Méndez-Sánchez,M. Martínez-Mares
Physics , 2012, DOI: 10.1103/PhysRevE.86.016207
Abstract: We study the scattering of waves in systems with losses or gains simulated by imaginary potentials. This is done for a complex delta potential that corresponds to a spatially localized absorption or amplification. In the Argand plane the scattering matrix moves on a circle $C$ centered on the real axis, but not at the origin, that is tangent to the unit circle. From the numerical simulations it is concluded that the distribution of the scattering matrix, when measured from the center of the circle $C$, agrees with the non-unitary Poisson kernel. This result is also obtained analytically by extending the analyticity condition, of unitary scattering matrices, to the non-unitary ones. We use this non-unitary Poisson kernel to obtain the distribution of non-unitary scattering matrices when measured from the origin of the Argand plane. The obtained marginal distributions have an excellent agreement with the numerical results.
Delay times in chaotic quantum systems
A. M. Martínez-Argüello,A. A. Fernández-Marín,M. Martínez-Mares
Physics , 2015,
Abstract: By an inductive reasoning, and based on recent results of the joint moments of proper delay times of open chaotic systems for ideal coupling to leads, we obtain a general expression for the distribution of the partial delay times for an arbitrary number of channels and any symmetry. This distribution was not completely known for all symmetry classes. Our theoretical distribution is verified by random matrix theory simulations of ballistic chaotic cavities.
Scattering of Elastic Waves in a Quasi-one-dimensional Cavity: Theory and Experiment
G. Báez,M. Cobián-Suárez,A. M. Martínez-Argüello,M. Martínez-Mares,R. A. Méndez-Sánchez
Physics , 2013,
Abstract: We study the scattering of torsional waves through a quasi-one-dimensional cavity both, from the experimental and theoretical points of view. The experiment consists of an elastic rod with square cross section. In order to form a cavity, a notch at a certain distance of one end of the rod was grooved. To absorb the waves, at the other side of the rod, a wedge, covered by an absorbing foam, was machined. In the theoretical description, the scattering matrix S of the torsional waves was obtained. The distribution of S is given by Poisson's kernel. The theoretical predictions show an excellent agreement with the experimental results. This experiment corresponds, in quantum mechanics, to the scattering by a delta potential, in one dimension, located at a certain distance from an impenetrable wall.
Electromagnetic prompt response in an elastic wave cavity
A. M. Martínez-Argüello,M. Martínez-Mares,M. Cobián-Suárez,G. Báez,R. A. Méndez-Sánchez
Physics , 2015,
Abstract: A rapid, or prompt response, of an electromagnetic nature, is found in an elastic wave scattering experiment. The experiment is performed with torsional elastic waves in a quasi-one-dimensional cavity with one port, formed by a notch grooved at a certain distance from the free end of a beam. The stationary patterns are diminished using a passive vibration isolation system at the other end of the beam. The measurement of the resonances is performed with non-contact electromagnetic-acoustic transducers outside the cavity. In the Argand plane, each resonance describes a circle over a base impedance curve which comes from the electromagnetic components of the equipment. A model, based on a variation of Poisson's kernel is developed. Excellent agreement between theory and experiment is obtained.
Testing quantum transport without decoherence
E. Flores-Olmedo,A. M. Martínez-Argüello,M. Martínez-Mares,G. Báez,J. A. Franco-Villafa?e,R. A. Méndez-Sánchez
Physics , 2015,
Abstract: The coherent electronic transport phenomena through quantum devices is difficult to observe due to thermal smearing and dephasing, the latter induced by inelastic scattering by phonons or impurities. In other wave systems, the temperature and dephasing may not destroy the coherence and can then be used to observe the underlying wave behaviour of the coherent quantum phenomena. Here, we observe coherent transmission of mechanical waves through a two-dimensional elastic Sinai billiard with two waveguides. The flexural-wave transmission performed by non-contact means, shows the transmission quantization when a new mode becomes open. In contrast with the quantum counterpart, these measurements agree with the theoretical predictions of the simplest model at zero temperature highlighting the universal character of the transmission fluctuations.
Trihalometanos en el agua de piscinas en cuatro zonas de Espa?a participantes en el proyecto INMA
Font-Ribera,Laia; Esplugues,Ana; Ballester,Ferran; Martínez-Argüelles,Bego?a; Tardón,Adonina; Freire,Carmen; Fernández,Marina F.; Carrasco,Gloria; Cases,Amparo; Sunyer,Jordi; Villanueva,Cristina M.;
Gaceta Sanitaria , 2010, DOI: 10.1590/S0213-91112010000600008
Abstract: objective: swimming is one of the most widely practiced sports in spain among people of all ages and physical conditions. this activity is also a source of exposure to disinfection by-products (dbp), which are potentially toxic. the dbp concentration in swimming pool water is not regulated and is poorly known. the aim of this study was to describe trihalomethane concentrations in swimming pool water in the municipalities of four cohorts of the inma project. methods: in july 2009, trihalomethanes were analyzed in water from 27 swimming pools in asturias, granada, valencia and sabadell. results: the mean total trihalomethane concentration was 42.7μg/l (standard deviation [sd]=19.1) in indoor pools and 151.2μg/l (sd=80.7) in outdoor pools. in all pools, the most abundant trihalomethane was always chloroform. the lowest levels were found in granada. conclusion: trihalomethane concentrations in swimming pool water were highly variable. outdoor swimming pools showed the highest levels, which were usually above the legal limit for drinking water.
Joint moments of proper delay times
Angel M. Mart\'\inez-Argüello,Moisés Martínez-Mares,Julio C. García
Mathematics , 2014, DOI: 10.1063/1.4890559
Abstract: We calculate negative moments of the $N$-dimensional Laguerre distribution for the orthogonal, unitary, and symplectic symmetries. These moments correspond to those of the proper delay times, which are needed to determine the statistical fluctuations of several transport properties through classically chaotic cavities, like quantum dots and microwave cavities with ideal coupling.
Estudio de las campa?as de vacunación antigripal 2005 y 2006 a trabajadores sanitarios del área 2 de Madrid
Pérez Bermúdez,B.; García Cebrián,M.; Martínez de Aramayona,Ma J.; Nieto Sánchez,A. B.; Ramos Argüello,C.; Aranda Vizcaíno,A.;
Medicina y Seguridad del Trabajo , 2007, DOI: 10.4321/S0465-546X2007000400008
Abstract: the vaccination against the influenza is the most effective way of preventing this illness. workers in the sanitary sector are ones of the most recommended to be vaccinated against the flu. objectives: to study whether there are significant differences between the 2005-2006 and 2006-2007 campaigns addressed to the workers in the sanitary area no 2 in the madrid community. methodology: descriptive study of both campaigns in the sanitary area no 2 in the madrid community. a uni-variant analysis is carried out to build a logistic regression model in which the two campaigns are the dependant variables. the following independent variables were also included: age, professional category, service, working center, previous year anti-flu vaccination, side effects in previous year, chronic diseases, medication taken, smoking habits and allergic processes. results: in the 2005 campaign, vaccination was more intense in central services, catering and administration. there were more side effects, more sanitary workers were vaccinated and more workers declared to have taken any sort of medication. however, in the 2006 campaign there were more vaccinations in the "h.u. la princesa", within the first week of campaign, in the medical services, and more workers declared to suffer any type of chronic disease. conclusions: the coverage of the vaccination has been equal or lower than in previous years in all working centers, with the exception of the "h.u. la princesa", where the coverage was higher.
The ABCA1 Gene R230C Variant Is Associated with Decreased Risk of Premature Coronary Artery Disease: The Genetics of Atherosclerotic Disease (GEA) Study
Teresa Villarreal-Molina, Carlos Posadas-Romero, Sandra Romero-Hidalgo, Erika Antúnez-Argüelles, Araceli Bautista-Grande, Gilberto Vargas-Alarcón, Eric Kimura-Hayama, Samuel Canizales-Quinteros, Juan Gabriel Juárez-Rojas, Rosalinda Posadas-Sánchez, Guillermo Cardoso-Salda?a, Aída Medina-Urrutia, María del Carmen González-Salazar, Rocío Martínez-Alvarado, Esteban Jorge-Galarza, Alessandra Carnevale
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049285
Abstract: Background ABCA1 genetic variation is known to play a role in HDL-C levels and various studies have also implicated ABCA1 variation in cardiovascular risk. The functional ABCA1/R230C variant is frequent in the Mexican population and has been consistently associated with low HDL-C concentrations. Although it has been associated with other cardiovascular risk factors such as obesity and type 2 diabetes mellitus, it is not known whether it is associated with coronary artery disease (CAD). Aim The purpose of the study was to analyze whether the ABCA1/R230C variant is associated with premature CAD in a case-control association study (GEA or Genetics of Atherosclerotic Disease), and to explore whether BMI modulates the effect of the C230 allele on other metabolic traits using a population-based design. Results The C230 allele was significantly associated with both lower HDL-C levels and a lower risk of premature CAD as compared to controls (OR = 0.566; Padd = 1.499×10?5). In addition, BMI modulated the effect of R230C on body fat distribution, as the correlation between BMI and visceral to subcutaneous adipose tissue (a metric of the propensity to store fat viscerally as compared to subcutaneously) was negative in RR homozygous individuals, but positive in premenopausal women bearing the C230 allele, with a statistically significant interaction (P = 0.005). BMI-R230C interaction was also significant for triglyceride levels in women regardless of their menopausal status (P = 0.036). Conclusion This is the first study assessing the effect of the R230C/ABCA1 variant in remature CAD. C230 was associated with both decreased HDL-C levels and a lower risk of premature CAD, and gender-specific BMI-R230C interactions were observed for different metabolic traits. These interactions may help explain inconsistencies in associations, and underscore the need to further analyze interactions of this functional and frequent variant with diet, exercise and other environmental factors.
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