Search results for "estadística"
showing 10 items of 196 documents
Effect of influenza-induced fever on human bioimpedance values.
2015
Background and Aims Bioelectrical impedance analysis (BIA) is a widely used technique to assess body composition and nutritional status. While bioelectrical values are affected by diverse variables, there has been little research on validation of BIA in acute illness, especially to understand prognostic significance. Here we report the use of BIA in acute febrile states induced by influenza. Methods Bioimpedance studies were conducted during an H1N1 influenza A outbreak in Venezuelan Amerindian villages from the Amazonas. Measurements were performed on 52 subjects between 1 and 40 years of age, and 7 children were re-examined after starting Oseltamivir treatment. Bioelectrical Impedance Vec…
The effect of cholecalciferol for lowering albuminuria in chronic kidney disease: a prospective controlled study.
2013
Background. Growing evidence indicates that vitamin D receptor activation may have antiproteinuric effects. We aimed to evaluate whether vitamin D supplementation with daily cholecalciferol could reduce albuminuria in proteinuric chronic kidney disease (CKD) patients. Methods. This 6-month prospective, controlled, intervention study enrolled 101 non-dialysis CKD patients with albuminuria. Patients with low 25(OH) vitamin D [25(OH)D] and high parathyroid hormone (PTH) levels (n = 50; 49%) received oral cholecalciferol (666 IU/day), whereas those without hyperparathyroidism (n = 51; 51%), independent of their vitamin D status, did not receive any cholecalciferol, and were considered as the co…
Shock control bump design optimization on natural laminar aerofoil
2011
The chapter investigates Shock Control Bumps (SCB) on a Natural Laminar Flow (NLF) aerofoil; RAE 5243 for Active Flow Control (AFC). A SCB approach is used to decelerate supersonic flow on the suction/pressure sides of transonic aerofoil that leads delaying shock occurrence or weakening of shock strength. Such an AFC technique reduces significantly the total drag at transonic speeds. This chapter considers the SCB shape design optimisation at two boundary layer transition positions (0 and 45%) using an Euler software coupled with viscous boundary layer effects and robust Evolutionary Algorithms (EAs). The optimisation method is based on a canonical Evolution Strategy (ES) algorithm and inco…
El análisis cuantitativo de trayectorias laborales. Un estado del arte
2022
La metodología cuantitativa aplicada al estudio de las trayectorias laborales ha experimentado un rápido auge que se ha extendido más allá del tradicional análisis de secuencias. El presente artículo es un estado del arte del desarrollo de nuevas técnicas estadísticas que pueden aplicarse o ya se aplican al estudio de trayectorias laborales. Además, incluimos sugerencias de software estadístico para la aplicación de cada una de las técnicas descritas. A lo largo de todo el texto, podrá observarse que la descripción de cada técnica se ha realizado desde un punto de vista conceptual, con el objetivo de llegar a un público amplio, que no necesite poseer una fuerte formación estadística. Es med…
Simulazione numerica tridimensionale del campi de moto indotti dal vento
2006
Nell’articolo viene proposto un modello numerico tridimensionale al volume finiti, che viene utilizzato per la simulazione di campi di moto indotti dal mento in corpi idrici con batimetria complessa. I risultati numerici sono confrontati con misure sperimentali. Al fine di verificare gli effetti sul calcolo del campi idrodinamici di alcume ipotesi simplificative, relative alla distribuzione verticale della pressione e degli sforzi di Reynolds, sono stati quindi condotti alcuni test numerici, dai quali si è evidenziato che l’ipotesi di distribuzione idrostatica delle pressioni, cui si fa ricorso nelle approssinazioni di tipo “quasi-3D”, può essere utilizzata per il carcolo del profili vertic…
Self-efficacy beliefs of university students: an empirical study on the specificity of the construct
2010
This study tested two propositions of the Social Cognitive Theory in an academic setting: a) Self-efficacy is a domain- specific competence belief; b) Domain-specific selfefficacy is related, but distinct from, other self-evaluation constructs. Participants (272 Spanish university students) completed measures of general self-efficacy, academic self-efficacy, statistics self-efficacy and attitudes towards statistics (cognitive and affective components). Principal Components Analyses and Confirmatory Factorial Analyses were performed, among other procedures. Taken as a whole, results support the propositions tested.
Bayesian hierarchical models for analysing the spatial distribution of bioclimatic indices
2017
A methodological approach for modelling the spatial distribution of bioclimatic indices is proposed in this paper. The value of the bioclimatic index is modelled with a hierarchical Bayesian model that incorporates both structured and unstructured random effects. Selection of prior distributions is also discussed in order to better incorporate any possible prior knowledge about the parameters that could refer to the particular characteristics of bioclimatic indices. MCMC methods and distributed programming are used to obtain an approximation of the posterior distribution of the parameters and also the posterior predictive distribution of the indices. One main outcome of the proposal is the …
Understanding disease mechanisms with statistical models of signaling pathway activities
2016
Hoy en día, uno de los temas más candentes en la investigación biomédica es entender los procesos que producen enfermedades. En el pasado, la mayor parte las enfermedades génicas fueron asociadas al mal funcionamiento de un solo gen, pero hay muchas enfermedades que sólo pueden ser explicadas por el mal funcionamiento de un conjunto de genes. Una vez el genoma humano fue secuenciado, se hizo evidente que los genes no actúan solos en la célula, si no que están unidos por una intrincada red de interacciones que determinan su actividad. Este descubrimiento dio lugar al inicio de la biología de sistemas, que trata de entender cómo los componentes celulares se relacionan entre ellos para dar lug…
Procedimento estratégico em três estágios de seleção de variáveis para a obtenção de resultados equilibrados na pesquisa em saúde pública
2018
Multidisciplinary research in public health is approached using methods from many scientific disciplines. One of the main characteristics of this type of research is dealing with large data sets. Classic statistical variable selection methods, known as “screen and clean”, and used in a single-step, select the variables with greater explanatory weight in the model. These methods, commonly used in public health research, may induce masking and multicollinearity, excluding relevant variables for the experts in each discipline and skewing the result. Some specific techniques are used to solve this problem, such as penalized regressions and Bayesian statistics, they offer more balanced results a…
Effects of Polyphenol, Measured by a Biomarker of Total Polyphenols in Urine, on Cardiovascular Risk Factors After a Long-Term Follow-Up in the PREDI…
2016
Several epidemiological studies have shown an inverse association between the consumption of polyphenol-rich foods and risk of cardiovascular diseases. However, accuracy and reliability of these studies may be increased using urinary total polyphenol excretion (TPE) as a biomarker for total polyphenol intake. Our aim was to assess if antioxidant activity, measured by a Folin-Ciocalteu assay in urine, is correlated with an improvement in cardiovascular risk factors (blood pressure and serum glucose, cholesterol, HDL-cholesterol, LDL-cholesterol, and triglyceride concentrations) in an elderly population at high risk. A longitudinal study was performed with 573 participants (aged 67.3 ± 5.9) f…