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Search Results: 1 - 10 of 25429 matches for " Salinas-Rodríguez "
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Polydispersity Effects in the Dynamics and Stability of Bubbling Flows
E. Salinas-Rodríguez,R. F. Rodríguez,J. M. Zamora,A. Soria
Physics , 2005, DOI: 10.1140/epjb/e2006-00128-7
Abstract: The occurrence of swarms of small bubbles in a variety of industrial systems enhances their performance. However, the effects that size polydispersity may produce on the stability of kinematic waves, the gain factor, mean bubble velocity, kinematic and dynamic wave velocities is, to our knowledge, not yet well established. We found that size polydispersity enhances the stability of a bubble column by a factor of about 23% as a function of frequency and for a particular type of bubble column. In this way our model predicts effects that might be verified experimentally but this, however, remain to be assessed. Our results reinforce the point of view advocated in this work in the sense that a description of a bubble column based on the concept of randomness of a bubble cloud and average properties of the fluid motion, may be a useful approach that has not been exploited in engineering systems.
Ríos de la reserva de la biosfera El Triunfo, un diagnóstico para su restauración ecológica
Salinas-Rodríguez, Sergio Alberto;Ramírez-Marcial, Neptalí;
Hidrobiológica , 2010,
Abstract: in recent years the rivers in "el triunfo" biosphere reserve (rebitri) and its influence area have increased their riverbanks in width because of high precipitation events, resulting in economic and human losses in the states of chiapas and tabasco. the objective of the present work was to identify, characterize, and diagnose five river sections to assess their ecological status inside of this natural area. multicriterion analysis was performed to define the sampling rivers sections; to quantify its changes and dynamism, were characterized geomorphological and hydrologically, and the gis analysis was complete through an aerial photos comparison to obtain composition and configuration index of each riparian landscape patch. the results indicate that the response of these rivers sections is mainly influenced by lack of tree cover on slopes. plant cover is essential to retain and absorb much water as product of the surface runoff on the slopes. therefore, the hydrological restoration projects must consider the tree cover reestablishment to balance erosion and sediment process relationship.
Modelo Hidrodinámico para la Velocidad de un Par de Burbujas Ascendiendo en Línea
Ramírez-Mu?oz,Jorge; Soria,Alberto; Salinas-Rodríguez,Elizabeth;
Información tecnológica , 2007, DOI: 10.4067/S0718-07642007000400010
Abstract: a hydrodynamic analysis on the interaction of two equal-size spherical bubbles aligned on the direction of a uniform, laminar, newtonian and incompressible flow, is presented. the leading bubble is considered as an isolated bubble and the trailing bubble (second bubble) is subjected to four forces: buoyancy, quasisteady drag, fluid impulse and added mass. by applying a force balance on each bubble, an expression for the rising velocity of the trailing bubble was obtained. comparison of this expression with existing experimental data for 3.06, 21.5 and 35.4 reynolds number was performed, obtaining a relative average error between 1.2% and 2.1%. two possible approaches on the trailing bubble drag reduction effect are discussed. it was found that a quasisteady drag is, by itself, unable to incorporate the whole wake effect on the trailing bubble.
Impacto del Seguro Popular en el gasto catastrófico y de bolsillo en el México rural y urbano, 2005-2008
Sosa-Rubí,Sandra G; Salinas-Rodríguez,Aarón; Galárraga,Omar;
Salud Pública de México , 2011, DOI: 10.1590/S0036-36342011001000006
Abstract: objective. to estimate the effect of "seguro popular" (sp) on the incidence of catastrophic health expenditure (che) and out-of-pocket (oop) health expenditure in the medium term. material and methods. we used the 'encuesta de evaluación del sp' -sp survey evaluation- (2005-2008). we analyzed the sp effect on the rural cohort during two years of follow-up (2006 and 2008) and in the urban cohort during one year of follow-up (2008). results. at the local level (regional clusters) we did not find an effect of the sp. at the household level we found a protective effect of sp on che and the oop health payments in outpatient and hospitalization in rural areas; and a significant effect on the reduction of oop health payments in outpatient services in urban zones. conclusions. sp seems to be an effective program to protect poor household against out-of-pocket health expenditures in the medium term.
Modelos de regresión para variables expresadas como una proporción continua
Salinas-Rodríguez,Aarón; Pérez-Nú?ez,Ricardo; ávila-Burgos,Leticia;
Salud Pública de México , 2006, DOI: 10.1590/S0036-36342006000500006
Abstract: objective: to describe some of the statistical alternatives available for studying continuous proportions and to compare them in order to show their advantages and disadvantages by means of their application in a practical example of the public health field. material and methods: from the national reproductive health survey performed in 2003, the proportion of individual coverage in the family planning program -proposed in one study carried out in the national institute of public health in cuernavaca, morelos, mexico (2005)- was modeled using the normal, gamma, beta and quasi-likelihood regression models. the akaike information criterion (aic) proposed by mcquarrie and tsai was used to define the best model. then, using a simulation (monte carlo/markov chains approach) a variable with a beta distribution was generated to evaluate the behavior of the 4 models while varying the sample size from 100 to 18 000 observations. results: results showed that the best statistical option for the analysis of continuous proportions was the beta regression model, since its assumptions are easily accomplished and because it had the lowest aic value. simulation evidenced that while the sample size increases the gamma, and even more so the quasi-likelihood, models come significantly close to the beta regression model. conclusions: the use of parametric beta regression is highly recommended to model continuous proportions and the normal model should be avoided. if the sample size is large enough, the use of quasi-likelihood model represents a good alternative.
Análisis estadístico para datos de conteo: aplicaciones para el uso de los servicios de salud
Salinas-Rodríguez,Aarón; Manrique-Espinoza,Betty; Sosa-Rubí,Sandra G;
Salud Pública de México , 2009, DOI: 10.1590/S0036-36342009000500007
Abstract: objective: to describe some of the statistical models for the study of count variables in the context of the use of health services. material and methods: we used the seguro popular evaluation survey to estimate the effect of seguro popular on the frequency of use of outpatient health services, using poisson regression models and negative binomial, zero-inflated negative binomial and the hurdle negative binomial models. we used the akaike information criterion (aic) to define the best model. results: results show that the best statistical approach to model the use of health services is the hurdle model, taking into account both the main theoretical assumptions and the statistical results of the aic. discussion: the modelling of count data requires the application of statistical models to model data dispersion; in the presence of an excess of zeros, the hurdle model is an appropriate statistical option.
Ríos de la reserva de la biosfera El Triunfo, un diagnóstico para su restauración ecológica "El Triunfo" biosphere reserve rivers, a diagnosis for their hydrological restoration
Sergio Alberto Salinas-Rodríguez,Neptalí Ramírez-Marcial
Hidrobiológica , 2010,
Abstract: En los últimos a os los ríos en la Reserva de la Biosfera "El Triunfo" (REBITRI) y su área de influencia, han incrementado su cauce a causa de eventos de alta precipitación, produciendo pérdidas humanas y económicas en los estados de Chiapas y Tabasco. El objetivo del presente trabajo fue identificar, caracterizar y diagnosticar el estado ecológico de cinco tramos de ríos dentro de esta área natural. Se realizó un análisis multicriterio para definir los tramos de muestreo; para cuantificar sus cambios y dinamismo, se caracterizaron geomorfológica e hidrológicamente y se completó el análisis SIG a través del trazado en planta de cada tramo para obtener índices de composición y configuración de cada componente del paisaje ripario. Los resultados indican que la respuesta de los ríos está mediada por la falta de cobertura vegetal arbórea, imprescindible como obstáculo para retener y absorber mayor cantidad de agua producto de la escorrentía superficial en las laderas de influencia de los segmentos de ríos analizados. Por lo tanto, los proyectos de restauración hidrológica deben considerar el restablecimiento de la cobertura vegetal para equilibrar la relación de los procesos de erosión y sedimentación. In recent years the rivers in "El Triunfo" Biosphere Reserve (REBITRI) and its influence area have increased their riverbanks in width because of high precipitation events, resulting in economic and human losses in the states of Chiapas and Tabasco. The objective of the present work was to identify, characterize, and diagnose five river sections to assess their ecological status inside of this natural area. Multicriterion analysis was performed to define the sampling rivers sections; to quantify its changes and dynamism, were characterized geomorphological and hydrologically, and the GIS analysis was complete through an aerial photos comparison to obtain composition and configuration index of each riparian landscape patch. The results indicate that the response of these rivers sections is mainly influenced by lack of tree cover on slopes. Plant cover is essential to retain and absorb much water as product of the surface runoff on the slopes. Therefore, the hydrological restoration projects must consider the tree cover reestablishment to balance erosion and sediment process relationship.
Modelo Hidrodinámico para la Velocidad de un Par de Burbujas Ascendiendo en Línea Hydrodynamic Model for the Velocity of a Bubble Pair Rising In-line
Jorge Ramírez-Mu?oz,Alberto Soria,Elizabeth Salinas-Rodríguez
Información Tecnológica , 2007,
Abstract: Se presenta un análisis hidrodinámico de la interacción de dos burbujas esféricas del mismo tama o alineadas en la dirección de un flujo uniforme, laminar, newtoniano e incompresible. La burbuja puntera se considera aislada y la burbuja acarreada (segunda burbuja) está sujeta a la acción de cuatro fuerzas: flotación, arrastre cuasiestacionario, impulso del fluido y masa agregada. Aplicando un balance de fuerzas sobre cada burbuja se obtuvo una nueva expresión para la velocidad de ascenso de la burbuja acarreada. La expresión se comparó con mediciones experimentales, realizadas por otros autores citados en la literatura, para números de Reynolds de 3.06, 21.5 y 35.4 y se obtuvo un error relativo promedio entre 1.2% y 2.1%. Se discuten dos alternativas para aproximar la reducción del arrastre sobre la burbuja acarreada. Se encontró que el arrastre cuasiestacionario no puede incorporar el efecto total de la estela sobre la burbuja acarreada A hydrodynamic analysis on the interaction of two equal-size spherical bubbles aligned on the direction of a uniform, laminar, newtonian and incompressible flow, is presented. The leading bubble is considered as an isolated bubble and the trailing bubble (second bubble) is subjected to four forces: buoyancy, quasisteady drag, fluid impulse and added mass. By applying a force balance on each bubble, an expression for the rising velocity of the trailing bubble was obtained. Comparison of this expression with existing experimental data for 3.06, 21.5 and 35.4 Reynolds number was performed, obtaining a relative average error between 1.2% and 2.1%. Two possible approaches on the trailing bubble drag reduction effect are discussed. It was found that a quasisteady drag is, by itself, unable to incorporate the whole wake effect on the trailing bubble.
NOTA SOBRE UN FRAGMENTO DE BOSQUE MESóFILO DE MONTA A DEL MUNICIPIO DE RíO VERDE, SAN LUIS POTOSí
MARíA MAGDALENA SALINAS-RODRíGUEZ,JUAN CRUZADO-CORTéS
Boletín de la Sociedad Botánica de México , 2011,
Abstract:
Prevalencia de dependencia funcional y su asociación con caídas en una muestra de adultos mayores pobres en México
Manrique-Espinoza,Betty; Salinas-Rodríguez,Aarón; Moreno-Tamayo,Karla; Téllez-Rojo,Martha M;
Salud Pública de México , 2011, DOI: 10.1590/S0036-36342011000100005
Abstract: objective: to determine the prevalence of functional dependency (fd) on mexican elderly living in extreme poverty conditions and to estimate the association between falls and fd. material and methods: a survey was conducted with three stages for selection, stratified by type of locality (rural or urban) and nationally representative of the 2006 oportunidades program. the target population was composed of individuals 70 years of age and older who were beneficiaries of the oportunidades program. results: a total of 30.9% of the elderly presented fd. the gender stratified logistic regression model resulted in an odds ratio (or) for women of 1.25 (i.c:1.13-1.39) for the association between the increase in the number of falls and fd and or=1.12 (i.c:0.97-1.29) for men. conclusions: given the vulnerable conditions in which these older adults live, specific interventions need to be implemented to prevent falls in order to reduce the risk of functional dependency.
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