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Search Results: 1 - 10 of 411229 matches for " Diego M.; Martinez "
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Partition function based analysis of CMB maps
J. M. Diego,E. Martinez-Gonzalez,J. L. Sanz,S. Mollerach,V. Martinez
Physics , 1999,
Abstract: We present an alternative method to analyse cosmic microwave background (CMB) maps. We base our analysis on the study of the partition function. This function is used to examine the CMB maps making use of the different information embedded at different scales and moments. Using the partition function in a likelihood analysis in two dimensions (Q_rms,n), we find the best-fitting model to the best data available at present the COBE--DMR 4 years data set. By means of this analysis we find a maximum in the likelihood function for n=1.8 (-0.65 +0.35) and Q_rms-PS = 10 (-2.5 +3) muK (95 % confidence level) in agreement with the results of other similar analyses (Smoot et al. 1994 (1 yr), Bennet et al. 1996 (4 yr)). Also making use of the partition function we perform a multifractal analysis and study the possible fractal nature of the CMB sky. We find that the measure used in the analysis is not a fractal. Finally, we use the partition function for testing the statistical distribution of the COBE--DMR data set. We conclude that no evidence of non-Gaussianity can be found by means of this method.
Tests of Gaussianity of CMB maps
E. Martinez-Gonzalez,B. Barreiro,J. M. Diego,J. L. Sanz,L. Cayon,J. Silk,S. Mollerach,V. Martinez
Physics , 2000,
Abstract: We study two different methods to test Gaussianity in CMB maps. One of them is based on the partition function and the other on the morphology of hot and cold spots. The partition function contains information on all the moments and scales, being a useful quantity to compress the large data sets expected from future space missions like Planck. In particular, it contains much richer information than the one available through the radiation power spectrum. The second method utilizes morphological properties of hot and cold spots such as the eccentricity and number of spots in CMB maps. We study the performance of both methods in detecting non-Gaussian features in small scale CMB simulated maps as those which will be provided by the Planck mission.
The roughness of the last scattering surface
Silvia Mollerach,Vicent J. Martinez,J. M. Diego,E. Martinez-Gonzalez,J. L. Sanz,Silvestre Paredes
Physics , 1999, DOI: 10.1086/307874
Abstract: We propose an alternative analysis of the microwave background temperature anisotropy maps that is based on the study of the roughness of natural surfaces. We apply it to large angle anisotropies, such as those measured by COBE-DMR. We show that for a large signal to noise experiment, the spectral index can be determined independently of the normalization. We then analyze the 4 yr COBE map and find for a flat $\Omega=1$ universe, that the best-fitting value for the spectral index is $n = 1.15^{+0.39}_{-0.34}$ and for the amplitude $Q_{rms-PS}= 14.1^{+3.9}_{-3.5}\mu K$. For $n=1$, the best-fitting normalization is $Q_{rms-PS}|_{n=1}= 16.2^{+1.4}_{-1.3}\mu K$.
Nueva evidencia epidemiológica y molecular a favor de la transmisión interhumana para el linaje Sout del hantavirus Andes
Pinna,Diego M.; Martinez,Valeria P.; Bellomo,Carla M.; López,Claudia; Padula,Paula;
Medicina (Buenos Aires) , 2004,
Abstract: after the hantavirus pulmonary syndrome (hps) outbreak occurred in southern argentina (patagonia) in 1996, a new mechanism of hantavirus spread was described for andes virus (and): person-to-person transmission. since then, this mode of transmission has been limited to the endemic area of and sout lineage. we report here an hps case, patient a, with residence in buenos aires province, whose unique epidemiological risk factor was to have shared a trip to southern argentina with an already ill person, later confirmed as an hps case (patient i). a third case (patient b), with residence in buenos aires province, developed hps after several contact events with patient a, with no additional risk factors. hantavirus infection was confirmed in all three patients by serological diagnosis and viral genetic characterization. the viral lineage characterized was and sout, being the same strain in the three cases. the clinical picture of patient a showed profound compromise, with gastrointestinal symptoms, with no clinical evidence of pulmonary involvement. in this work we present new evidence supporting person-to-person transmission for and sout lineage, where there was an only contact with the index case, occasional, prolonged and non-repeated, established out of the endemic area for and sout lineage.
Nueva evidencia epidemiológica y molecular a favor de la transmisión interhumana para el linaje Sout del hantavirus Andes New epidemiologic and molecular evidence of person to person transmission of hantavirus Andes Sout
Diego M. Pinna,Valeria P. Martinez,Carla M. Bellomo,Claudia López
Medicina (Buenos Aires) , 2004,
Abstract: A partir de un brote de síndrome pulmonar por hantavirus ocurrido en 1996 en el sur de Argentina un nuevo mecanismo de infección quedó demostrado para el virus Andes (AND): la transmisión viral de persona a persona. La sospecha de ocurrencia de este mecanismo de transmisión ha sido restringida a la zona endémica del linaje AND Sout. Describimos el caso de un paciente (caso A) residente en Buenos Aires, que desarrolló una infección por hantavirus sin haber tenido ningún otro riesgo epidemiológico más que el contacto con un caso previo (caso I) en un viaje al sur de Argentina. Posteriormente un tercer caso (caso B) residente de la provincia de Buenos Aires, desarrolló un síndrome pulmonar por hantavirus (SPH) teniendo como antecedente de riesgo varios encuentros con A. La confirmación de la enfermedad en los tres pacientes se realizó mediante diagnóstico serológico y caracterización genética viral. El linaje viral en los tres casos fue el AND Sout siendo idéntica la cepa viral. Entre los hallazgos clínicos del caso A es destacable el gran compromiso general, con síntomas gastrointestinales pero sin evidencia clínica de da o pulmonar. En el presente informe presentamos nueva evidencia para el mecanismo de transmisión interhumana del linaje AND Sout, con las características particulares de haber ocurrido por un contacto ocasional, no repetido, pero prolongado como un viaje en ómnibus de larga distancia y fuera del área endémica. After the Hantavirus Pulmonary Syndrome (HPS) outbreak occurred in Southern Argentina (Patagonia) in 1996, a new mechanism of hantavirus spread was described for Andes virus (AND): person-to-person transmission. Since then, this mode of transmission has been limited to the endemic area of AND Sout lineage. We report here an HPS case, patient A, with residence in Buenos Aires Province, whose unique epidemiological risk factor was to have shared a trip to Southern Argentina with an already ill person, later confirmed as an HPS case (patient I). A third case (patient B), with residence in Buenos Aires Province, developed HPS after several contact events with patient A, with no additional risk factors. Hantavirus infection was confirmed in all three patients by serological diagnosis and viral genetic characterization. The viral lineage characterized was AND Sout, being the same strain in the three cases. The clinical picture of patient A showed profound compromise, with gastrointestinal symptoms, with no clinical evidence of pulmonary involvement. In this work we present new evidence supporting person-to-person transmission for AND Sout
A biochemical hypothesis on the formation of fingerprints using a turing patterns approach
Diego A Garzón-Alvarado, Angelica M Ramírez Martinez
Theoretical Biology and Medical Modelling , 2011, DOI: 10.1186/1742-4682-8-24
Abstract: Several numerical examples were solved regarding simplified finger geometries to study pattern formation. The finite element method was used for numerical solution, in conjunction with the Newton-Raphson method to approximate nonlinear partial differential equations.The numerical examples showed that the model could represent the formation of different types of fingerprint characteristics in each individual.Fingerprints represent a particular characteristic for each individual [1-10]. These enable individuals to be identified through the embossed patterns formed on fingertips. Characteristic patterns are also formed on the palms of the hands and soles of the feet [1]. Their origin and development is still unknown but it is believed to have a strong genetic component, although it is not the only thing determining its formation. Each fingerprint is a papillary drawing composed by papillae and rete ridges (crests) [1-6]. These crests are epidermal ridges having unique characteristics [1].Characteristic fingerprint patterns begin their formation by the sixth month of gestation [1-6]. Such formation is unchangeable until an individual's death. No two fingerprints are identical; they thus become an excellent identification tool [1,2]. Various theories have been proposed concerning fingerprint formation; among the most accepted are those that consider differential forces on the skin (mechanical theory) [1,6,7] and those having a genetic component [1,6,10]. From a mechanical point of view, it has been considered that fingerprints are produced by the interaction of nonlinear elastic forces between the dermis and epidermis [7]. This theory considers that the growth of the fingers in the embryo (dermis) is different than growth in the epidermis, resulting in folds in the skin surface [7]. Figure 1 shows a mechanical explanation for the formation of the folds that give rise to fingerprints.Fingers are separated from each other in the fetus during embryonic formation during the
PROPAGACIóN In vitro DE Heliconia curtispatha P, PLANTA UTILIZADA CONTRA LA MORDEDURA DE SERPIENTES POR ALGUNAS COMUNIDADES CAMPESINAS DE LA REGIóN COLOMBIANA DEL URABá
ALARCóN P,Juan C; MARTINEZ R,Diego M; SALAZAR-OSPINA,Andrea;
Vitae , 2011,
Abstract: heliconia curtispatha petersen (zingiberales) commonly known as platanillo, is used in colombian traditional medicine by its anti-edema, antihaemorrhagic and neutralising action of bothrops asper (mapaná, x) venom, responsible for 95% of snakebites in the country. the previous, emphasizes its utility and potential function as helper in the treatment of the ophidian accident. the in vitro propagation techniques becomes an interesting tool for plant and metabolites production, because of the hazardous accessibility to plants in their natural environment and the deficiency of previous studies on in vitro multiplication of the specie. in the present work, plantlets are obtained from seeds and its in vitro p ropagation is evaluated in murashige & skoog semi-solid and liquid medium without or in combination with citokinines-like. experimentally, it promotes the propagation of heliconia (2 weeks outbreaks -1) when using murashige & skoog liquid medium without added growth regulators or by using murashige & skoog semisolid adding 2 mg.l-1 6-benzylaminopurine 0.93 week outbreaks -1. this is the first report of in vitro propagation of h. curtispatha and the first step for the study of secondary metabolites with potential venom that can occur under such conditions.
PROPAGACIóN In vitro DE Heliconia curtispatha P, PLANTA UTILIZADA CONTRA LA MORDEDURA DE SERPIENTES POR ALGUNAS COMUNIDADES CAMPESINAS DE LA REGIóN COLOMBIANA DEL URABá In vitro PROPAGATION OF Heliconia curtispatha P, PLANT USED AGAINST SNAKEBITE BY SOME RURAL COMMUNITIES OF THE COLOMBIAN REGION OF URABá
Juan C ALARCóN P,Diego M MARTINEZ R,Andrea SALAZAR-OSPINA
Vitae , 2011,
Abstract: Heliconia curtispatha Petersen (Zingiberales) comúnmente conocida como platanillo, es usada en la medicina tradicional colombiana por su acción antiedematizante, antihemorrágica y neutralizante del veneno de Bothrops asper (mapaná) responsable del 95% de las mordeduras de serpientes en el país. Lo anterior destaca su utilidad y potencial función, como coadyuvante en el tratamiento del accidente ofídico. La propagación por cultivos in vitro, se convierte en una herramienta valiosa e interesante para su masificación, debido al difícil acceso al material vegetal en su ambiente natural y la carencia de estudios previos en multiplicación in vitro de esta especie. En el presente trabajo se obtienen plántulas a partir de semillas y se evalúa su propagación en medios de cultivo Murashige & Skoog, semisólidos y líquidos suplementados con reguladores de crecimiento tipo citoquinina. Experimentalmente, se favorece la propagación de la Heliconia (2 brotes semana-1) cuando se utiliza medio Murashige & Skoog líquido sin adición de reguladores de crecimiento o al emplear Murashige & Skoog semisólido adicionándole 2 mg.L-1 6-Bencilaminopurina 0.93 brotes.semana-1. Este es el primer reporte de propagación in vitro de H. curtispatha y el primer paso para el estudio de metabolitos secundarios con potencial antiofídico que pueden producirse bajo tales condiciones. Heliconia curtispatha Petersen (Zingiberales) commonly known as platanillo, is used in colombian traditional medicine by its anti-edema, antihaemorrhagic and neutralising action of Bothrops asper (mapaná, X) venom, responsible for 95% of snakebites in the country. The previous, emphasizes its utility and potential function as helper in the treatment of the ophidian accident. The in vitro propagation techniques becomes an interesting tool for plant and metabolites production, because of the hazardous accessibility to plants in their natural environment and the deficiency of previous studies on in vitro multiplication of the specie. In the present work, plantlets are obtained from seeds and its in vitro p ropagation is evaluated in Murashige & Skoog semi-solid and liquid medium without or in combination with citokinines-like. Experimentally, it promotes the propagation of Heliconia (2 weeks outbreaks -1) when using Murashige & Skoog liquid medium without added growth regulators or by using Murashige & Skoog semisolid adding 2 mg.L-1 6-benzylaminopurine 0.93 week outbreaks -1. This is the first report of in vitro propagation of H. curtispatha and the first step for the study of secondary metabolites with potential v
Admission Control and Interference Management in Dynamic Spectrum Access Networks
Jorge Martinez-Bauset,Vicent Pla,M. Jose Domenech-Benlloch,Diego Pacheco-Paramo
EURASIP Journal on Wireless Communications and Networking , 2010, DOI: 10.1155/2010/708029
Abstract: We study two important aspects to make dynamic spectrum access work in practice: the admission policy of secondary users (SUs) to achieve a certain degree of quality of service and the management of the interference caused by SUs to primary users (PUs). In order to limit the forced termination probability of SUs, we evaluate the Fractional Guard Channel reservation scheme to give priority to spectrum handovers over new arrivals. We show that, contrary to what has been proposed, the throughput of SUs cannot be maximized by configuring the reservation parameter. We also study the interference caused by SUs to PUs. We propose and evaluate different mechanisms to reduce the interference, which are based on simple spectrum access algorithms for both PUs and SUs and channel repacking algorithms for SUs. Numerical results show that the reduction can be of one order of magnitude or more with respect to the random access case. Finally, we propose an adaptive admission control scheme that is able to limit simultaneously the forced termination probability of SUs and what we define as the probability of interference. Our scheme does not require any configuration parameters beyond the probability objectives. Besides, it is simple to implement and it can operate with any arrival process and distribution of the session duration.
CMB power spectrum estimation and map reconstruction with the Expectation - Maximization algorithm
E. Martinez-Gonzalez,J. M. Diego,P. Vielva,J. Silk
Physics , 2003, DOI: 10.1046/j.1365-2966.2003.06885.x
Abstract: We apply the iterative Expectation-Maximization algorithm (EM) to estimate the power spectrum of the CMB from multifrequency microwave maps. In addition, we are also able to provide a reconstruction of the CMB map. By assuming that the combined emission of the foregrounds plus the instrumental noise is Gaussian distributed in Fourier space, we have simplified the EM procedure finding an analytical expression for the maximization step. By using the simplified expression the CPU time can be greatly reduced. We test the stability of our power spectrum estimator with realistic simulations of Planck data, including point sources and allowing for spatial variation of the frequency dependence of the Galactic emissions. Without prior information about any of the components, our new estimator can recover the CMB power spectrum up to scales l~1500 with less than 10% error. This result is significantly improved if the brightest point sources are removed before applying our estimator. In this way, the CMB power spectrum can be recovered up to l~1700 with 10% error and up to l~2100 with 50% error. This result is very close to the one that would be obtained in the ideal case of only CMB plus white noise, for which all our assumptions are satisfied. Moreover, the EM algorithm also provides an straightforward mechanism to reconstruct the CMB map. The recovered cosmological signal shows a high degree of correlation (r = 0.98) with the input map and low residuals.
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