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Search Results: 1 - 10 of 334386 matches for " Frank; Sánchez Corales "
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Técnicas de minería de datos aplicadas al diagnóstico de entidades clínicas
Dávila Hernández,Frank; Sánchez Corales,Yovannys;
Revista Cubana de Inform??tica M??dica , 2012,
Abstract: reduce medical errors and improve health processes is a priority of all health personnel. in this context arise the "clinical support systems for decision making" (cdss), which are a key component in computerization of the clinical layer. with the evolution of technologies, large amounts of data have been studied and classified based on data mining. one of the main advantages of using this in the cdss, has been its ability to generate new knowledge. for this purpose, this paper presents, by combining two mathematical models, a way to contribute to the diagnosis of diseases using data mining techniques. hypertension was taken as a case study to show the models used. the research development methodology follows the most used processes of knowledge discovery in databases: crisp-dm 1.0, and relies on the free distribution tool weka 3.6.2. we obtained different patterns of behavior in relation to risk factors for developing hypertension using data mining techniques.
Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM
Frank Hubenthal,David Blázquez Sánchez,Frank Tr?ger
Applied Sciences , 2012, DOI: 10.3390/app2030566
Abstract: The morphology of small gold particles prepared by Volmer–Weber growth on sapphire substrates have been investigated by two different characterization techniques. First, by non-extensive atomic force microscopy (AFM) in combination with optical spectroscopy and modeling of the optical properties using a theoretical model, recently developed in our group. Second, by extensive transmission electron microscopy (TEM). Comparing the results obtained with both techniques demonstrate that for small gold nanoparticles within the quasistatic limit, the morphological properties can be precisely determined by an appropriate theoretical modeling of the optical properties in combination with simple AFM measurements. The apparent mean axial ratio of the nanoparticles, i.e., the axial ratio that corresponds to the center frequency of the ensemble plasmon resonance, is obtained easily from the extinction spectrum. The mean size is determined by the nanoparticle number density and the amount of deposited material, measured by AFM and a quartz micro balance, respectively. To extract the most probable axial ratio of the nanoparticle ensemble, i.e., the axial ratio that corresponds to the most probable nanoparticle size in the ensemble, we apply the new theoretical model, which allows to extract the functional dependence of the nanoparticle shape on its size. The morphological parameters obtained with this procedure will be afterwards compared to extensive TEM measurements. The results obtained with both techniques yield excellent agreement. For example, the lateral dimensions of the nanoparticles after deposition of 15.2 × 10 15 atoms/cm 2 of gold has been compared. While a mean lateral diameter of (13 ± 2) nm has been extracted from AFM, optical spectroscopy and modeling, a value of (12 ± 2) nm is derived from TEM. The consistency of the results demonstrate the precision of our new model. Moreover, since our theoretical model allows to extract the functional dependence of the nanoparticle size and shape, a relatively simple analysis is sufficient for a full characterization of small noble metal nanoparticles.
Evaluación biométrica de dos variedades de papa, en la zona alta del estado Falcón, Venezuela
Zamora,Frank R; Sánchez Gutiérrez,Alexander; Tua,Domingo;
Agronomía Tropical , 2008,
Abstract: in order to offer agronomic alternative to the small farmers of the federation council, falcon state, two varieties of potato were evaluated, s. tuberosum l.; kennebec (vk) and atlantic (va), in the sabanita area, located to 800 meters up sea level, characterized as premontain humid forest, with precipitations of 1000 mm per year and structured soils with mean levels of organic matter. the experimental design used was random blocks with three repetitions, the variable evaluated were: plant height (ph), stem thickness (st), stem number (sn); also biometric parameters were evaluates such as: tuber number (tn), plants weight (pw), fresh weight (fw) and dry matter (dm), yield by plant (yp) and yield by hectare (kg ha-1). for both varieties the (ts) was similar (p>0,01), while the parameters; ntp, ptp, rp and rha showed significant differences (p<0,01) between the varieties evaluated, being superior vk. a high productive potential demonstrated by vk, suggest that this variety is an alternative in the diversification of the traditional production systems of the high zone of the state falcon.
Diversity-induced resonance in the response to social norms
Claudio J. Tessone,Angel Sánchez,Frank Schweitzer
Computer Science , 2012, DOI: 10.1103/PhysRevE.87.022803
Abstract: In this paper we focus on diversity-induced resonance, which was recently found in bistable, excitable and other physical systems. We study the appearance of this phenomenon in a purely economic model of cooperating and defecting agents. Agent's contribution to a public good is seen as a social norm. So defecting agents face a social pressure, which decreases if free-riding becomes widespread. In this model, diversity among agents naturally appears because of the different sensitivity towards the social norm. We study the evolution of cooperation as a response to the social norm (i) for the replicator dynamics, and (ii) for the logit dynamics by means of numerical simulations. Diversity-induced resonance is observed as a maximum in the response of agents to changes in the social norm as a function of the degree of heterogeneity in the population. We provide an analytical, mean-field approach for the logit dynamics and find very good agreement with the simulations. From a socio-economic perspective, our results show that, counter-intuitively, diversity in the individual sensitivity to social norms may result in a society that better follows such norms as a whole, even if part of the population is less prone to follow them.
Utilidad de los registros intracavitarios en la ablación de las taquicardias por reentrada nodal (reporte de 3 casos). Usefulnes of intracavitary recording in the ablation of nodal reentry tachycardia.
Roberto Zayas Molina,Jsús Castro Hevia,Margarita Dorantes Sánchez,Frank Tornés
Revista Cubana de Cardiología y Cirugía Cardiovascular , 1999,
Abstract: Se analizó los resultados obtenidos en 3 pacientes portadores de taquicardia por reentrada nodal, a quienes se les realizó ablación con radiofrecuencia. Con las aplicaciones de energía en el tercio inferior del triángulo de Koch, sitio de salida de la vía de conducción lenta, se destruyó la rápida y se provocó un bloqueo auriculoventricular transitorio. Dos pacientes quedaron con un intervalo PR prolongado y los 3 sin conducción retrógrada. El registro del seno coronario durante las aplicaciones permitió definir alargamientos del intervalo ventriculoauricular durante el ritmo de unión, que manifestaron la lesión de la vía rápida retrógrada y conducción por la lenta. Se concluye que la prolongación del intervalo ventriculoauricular que aparece con el ritmo de unión durante las aplicaciones de radiofrecuencia, puede ser un marcador que defina la lesión de la vía de conducción nodal rápida. El registro intracardíaco (seno coronario) resulta imprescindible para hacer este diagnóstico. The results obtained in 3 patient carriers of nodal reentry tachycardia that underwent ablation with radiofrecuency were analized. With the applications of energy on the lower third of Koch's triangle, an exit site of the slow patway conduction, the fast patway was destroyed and a temporary auriculoventricular block was produced. 2 of the patients had a proonged P-R interval and the 3 of them had no retrograde conduction. The recording of the coronary simus during the applications allowed to define enlargements of the ventriculoauricular interval during the coupled rhythm that showed the injury of the retrograde fast pathway and the conduction by the slow pathway. It is concluded that the prolongation of the ventriculoauricular interval appearing with the coupled rhythm dirung the applications of radiofrequency may be a marker that defines the of the fast patway nodal conduction. the intracardiac recording (caronary sinus) is indispensable to make this diagnosis.
Modelo matemático para la caracterización del envejecimiento del acero 12Cr1MoV superenvejecido a partir del efecto Barkhausen
de los Reyes-Rodríguez,Frank; Capó-Sánchez,Julio; Franco-Fidalgo,Eduardo;
Ingenier?-a Mec??nica , 2012,
Abstract: in this work, a mathematical model to characterize the ageing degree on 12cr1mov steel used on main steam pipes from power plants is developed. this model start from bertotti′s model about the variation of magnetic flux with the time, obtaining different mathematics expressions which relate the induced voltage on the coil and known as magnetic barkhausen noise (mbn) with grain and carbides size, which constitute, among others parameters, one that can be used to evaluate the ageing process on the analyzed steel, with the developed model a decreasing and increasing later of voltage with the increasing of grain and carbide size respectively for the same magnetic field applied is verified, with this result it is possible to corroborate the magnetic measurements which be developed using mbn on practice applications.
Antioxidant effect of an ozonized theobroma oil formulation on damaged-inflammatory rat skin
Sánchez, Yaima,Díaz, Maritza F.,Hernández, Frank,Gil, Dayana
Grasas y Aceites , 2011, DOI: 10.3989/gya.055710
Abstract: The aim of this study was to determine whether a cosmetic formulation elaborated with ozonized theobroma oil may exert beneficial effects in the restoring of the antioxidant activity on the skin of rats previously irradiated with ultraviolet light. 0.5 g of the formulation was applied on the skin of rats for five days. Superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activity were determined in a homogenate of rat skin. Malondialdehyde (MDA), conjugated dienes (CD) and total hydroperoxide (THP) content were determined as biomarkers of oxidative stress. Using these parameters, antioxidant and oxidant activity, redox index and oxidative stress grade were determined. The total antioxidant activity was significantly increased while the redox index, total oxidant activity and oxidative stress grade decreased significantly in damaged rats treated with the formulation. These results show the antioxidant properties of the cosmetic formulation due to the stimulation of antioxidant enzymes such as SOD and GPx, preventing skin injury induced by ultraviolet irradiation. El objetivo de este estudio fue determinar si una formulación cosmética elaborada con aceite de teobroma ozonizado puede ejercer efectos beneficiosos en la restauración de la actividad antioxidante sobre la piel de ratas previamente irradiadas con luz ultravioleta. Fue aplicada 0,5 g de la formulación sobre la piel de ratas durante cinco días. La actividad de las enzimas superóxido dismutasa (SOD), glutatión peroxidasa (GPx), y catalasa fueron determinadas en homogeneizado de piel de ratas. Los contenidos de malonildialdehído (MDA), dienos conjugados (DC) e hidroperóxidos totales (HPT) fueron considerados como los biomarcadores de da o oxidativo. Con todos estos parámetros fueron determinados las actividades antioxidantes y oxídantes, índice redox y grado de estrés oxidativo. La actividad antioxidante total fue incrementada significativamente, mientras que el índice redox, la actividad oxidante y el grado de estrés oxidativo disminuyó significativamente, en ratas da adas tratadas con la formulación. Estos resultados evidencian las propiedades antioxidantes de la formulación cosmética debido a la estimulación de enzimas antioxidantes tales como SOD o GPx, previniendo el da o en la piel inducido por radiación ultravioleta.
Informe de la evaluación de las XI Jornadas Costarricenses de Medicina Legal y I Congreso de Medicina Legal Laboral
Carlos Abarca Barrantes,Ana Tristán Sánchez,Frank Alvarado Céspedes
Medicina Legal de Costa Rica , 1997,
Abstract:
Using Multiple Imputation for Vote Choice Data: A Comparison across Multiple Imputation Tools  [PDF]
Frank C. S. Liu
Open Journal of Political Science (OJPS) , 2014, DOI: 10.4236/ojps.2014.42006
Abstract:

One commonly acknowledged challenge in polls or surveys is item non-response, i.e., a significant proportion of respondents conceal their preferences about particular questions. This paper applies the multiple imputation (MI) method to reconstruct the distribution of vote choice in the sample. Vote choice is one of most important dependent variables in political science studies. This paper shows how the MI procedure in general facilitates the work of reconstructing the distribution of a targeted variable. Particularly, it shows how MI can be applied to point-estimation in descriptive statistics. The three packages of R, AmeliaII, MICE, and mi, are employed for this project. The findings, based on a Taiwan Election and Democratization Study (TEDS) samples collected after the 2012 presidential election (N = 1826) suggest the following: First, there is little adjustment done given the MI methods; Second, the three tools based on two algorithms lead to similar results, while Amelia II and MICE perform better. Although the results are not striking, the implications of these findings are worthy of discussion.

Chagas Disease Risk in Texas
Sahotra Sarkar ,Stavana E. Strutz,David M. Frank,Chissa–Louise Rivaldi,Blake Sissel,Victor Sánchez–Cordero
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000836
Abstract: Background Chagas disease, caused by Trypanosoma cruzi, remains a serious public health concern in many areas of Latin America, including México. It is also endemic in Texas with an autochthonous canine cycle, abundant vectors (Triatoma species) in many counties, and established domestic and peridomestic cycles which make competent reservoirs available throughout the state. Yet, Chagas disease is not reportable in Texas, blood donor screening is not mandatory, and the serological profiles of human and canine populations remain unknown. The purpose of this analysis was to provide a formal risk assessment, including risk maps, which recommends the removal of these lacunae. Methods and Findings The spatial relative risk of the establishment of autochthonous Chagas disease cycles in Texas was assessed using a five–stage analysis. 1. Ecological risk for Chagas disease was established at a fine spatial resolution using a maximum entropy algorithm that takes as input occurrence points of vectors and environmental layers. The analysis was restricted to triatomine vector species for which new data were generated through field collection and through collation of post–1960 museum records in both México and the United States with sufficiently low georeferenced error to be admissible given the spatial resolution of the analysis (1 arc–minute). The new data extended the distribution of vector species to 10 new Texas counties. The models predicted that Triatoma gerstaeckeri has a large region of contiguous suitable habitat in the southern United States and México, T. lecticularia has a diffuse suitable habitat distribution along both coasts of the same region, and T. sanguisuga has a disjoint suitable habitat distribution along the coasts of the United States. The ecological risk is highest in south Texas. 2. Incidence–based relative risk was computed at the county level using the Bayesian Besag–York–Mollié model and post–1960 T. cruzi incidence data. This risk is concentrated in south Texas. 3. The ecological and incidence–based risks were analyzed together in a multi–criteria dominance analysis of all counties and those counties in which there were as yet no reports of parasite incidence. Both analyses picked out counties in south Texas as those at highest risk. 4. As an alternative to the multi–criteria analysis, the ecological and incidence–based risks were compounded in a multiplicative composite risk model. Counties in south Texas emerged as those with the highest risk. 5. Risk as the relative expected exposure rate was computed using a multiplicative model for
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