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Search Results: 1 - 10 of 199130 matches for " Barrón-Meza "
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Vibration Analysis Of a Self-Excited Elastic Beam
Barrón-Meza, M. A.;
Journal of applied research and technology , 2010,
Abstract: the vibration behavior and the energy exchange among the normal modes of a clamped-free self-excited elastic beam are analyzed in this work. to model this kind of beam, the damping term of a van der pol oscillator is directly added to the equation of a linear elastic beam, yielding a single nonlinear partial differential equation. to solve this equation, a spectral method is employed. three vibration modes are considered in the analysis, and the values of the self-exciting constant are varied in order to cover from linear to nonlinear vibration behavior. multiple frequencies of the nonlinear beam are determined through the power spectral density of the beam free-end time series. given that this relatively simple model mimics at least in a qualitative way some key issues of the fluid-structure problem, it could be potentially useful for fatigue studies and vibration analysis of rotating blades in turbomachinery.
Maltrato infantil y del adolescente registrado en un hospital de referencia nacional, 2006 - 2011
Escalante-Romero,Lorena; Huamaní,Charles; Serpa,Hilda; Urbano-Durand,Carlos; Farfán-Meza,Gaudy; Ferrer-Salas,Carolina; Granados-Chávez,Gilda;
Revista Peruana de Medicina Experimental y Salud Pública , 2012, DOI: 10.1590/S1726-46342012000100005
Abstract: objectives. to describe the records of child and adolescent abuse of the instituto nacional de salud del ni?o (insn) from january 2006 to september 2011, characterizing the victim and perpetrator. materials and methods. a secondary sources analysis was performed, based on the domestic violence and child abuse records, from froms administered by child abuse and adolescent health unit (mamis) at the insn. the records include data of the victim, offender and characteristics of the aggression. types of aggression were categorized as: sexual, physical, psychological or neglection. frequencies and percentages are presented. results. a total of 1798 records were included. from them 63.9% were girls, and 39.9% were adolescents. males accounted for 60.6% of the offenders, and 65.8% of assaults occurred at home. sexual assault was recorded in 48.6%, with more frequency among girls (73.2%) and adolescents (44.4%); and intercourse occurred in 9.6% of the cases. conclusions. from the insn mamis records, aggressions to girls was the most frequent type of report, the aggressor was often a male and most of the attacks occurred in the child’s home. sexual assault accounted for almost half of the series.
Effect of a hydrogymnastics program on the serum levels of high-sensitivity C-reactive protein amongst elderly women  [PDF]
Javier Arturo Hall-López, Paulina Yesica Ochoa-Martínez, Edgar Ismael Alarcón-Meza, Fernando Israel Anaya-Jaramillo, Ana María Miranda Botelho Teixeira, José Moncada-Jiménez, José Carlos Ferreira-Reis, Estélio Henrique Martin Dantas
Health (Health) , 2014, DOI: 10.4236/health.2014.61012
Abstract:

The aim of this study was to evaluate the effect of a hydrogymnastics training program on highsensitivity C-reactive protein in elderly women. The subjects were randomly divided into the experimental group who participates in the hydrogymnastics training program and the control group who was not involved in the training and remained sedentary. The serum levels of highsensitivity C-reactive protein were determined by immunoturbidimetry using C-reactive protein (CRP), the training protocol consisted of hydrogymnastics sessions 5 times per week during 12 weeks of intervention, executed in a pool of 1.3 meters divided into three phases: a 10-minute warm-up, 30 minutes of aerobic exercise at 50%-60% of maximum heart rate (monitored by heart rate monitor) and a 10-minute cool down. As a statistical method to compare the results between groups of variables pre and post training, the analysis of variance (ANOVA) mixed 2 × 2 (group × measurement) test was done using SPSS version 17. The founds showed significant changes in the level of high-sensitivity C-reactive protein, and a greater percentage decrease of hs-CRP (Δ%= -37%, p = 0.001) in the experimental group in relation to the control group.Therefore, it can be inferred that a hydrogymnastics program is effective in reducing the metabolic rate of high-sensitivity C-reactive protein amongst elderly women.

Engineering Escherichia coli to increase plasmid DNA production in high cell-density cultivations in batch mode
Borja Gheorghe M,Meza Mora Eugenio,Barrón Blanca,Gosset Guillermo
Microbial Cell Factories , 2012, DOI: 10.1186/1475-2859-11-132
Abstract: Background Plasmid DNA (pDNA) is a promising molecule for therapeutic applications. pDNA is produced by Escherichia coli in high cell-density cultivations (HCDC) using fed-batch mode. The typical limitations of such cultivations, including metabolic deviations like aerobic acetate production due to the existence of substrate gradients in large-scale bioreactors, remain as serious challenges for fast and effective pDNA production. We have previously demonstrated that the substitution of the phosphotransferase system by the over-expressed galactose permease for glucose uptake in E. coli (strain VH33) allows efficient growth, while strongly decreases acetate production. In the present work, additional genetic modifications were made to VH33 to further improve pDNA production. Several genes were deleted from strain VH33: the recA, deoR, nupG and endA genes were inactivated independently and in combination. The performance of the mutant strains was evaluated in shake flasks for the production of a 6.1 kb plasmid bearing an antigen gene against mumps. The best producer strain was cultivated in lab-scale bioreactors using 100 g/L of glucose to achieve HCDC in batch mode. For comparison, the widely used commercial strain DH5α, carrying the same plasmid, was also cultivated under the same conditions. Results The various mutations tested had different effects on the specific growth rate, glucose uptake rate, and pDNA yields (YP/X). The triple mutant VH33 Δ (recA deoR nupG) accumulated low amounts of acetate and resulted in the best YP/X (4.22 mg/g), whereas YP/X of strain VH33 only reached 1.16 mg/g. When cultivated at high glucose concentrations, the triple mutant strain produced 186 mg/L of pDNA, 40 g/L of biomass and only 2.2 g/L of acetate. In contrast, DH5α produced only 70 mg/L of pDNA and accumulated 9.5 g/L of acetate. Furthermore, the supercoiled fraction of the pDNA produced by the triple mutant was nearly constant throughout the cultivation. Conclusion The pDNA concentration obtained with the engineered strain VH33 Δ (recA deoR nupG) is, to the best of our knowledge, the highest reported for a batch cultivation, and its supercoiled fraction remained close to 80%. Strain VH33 Δ (recA deoR nupG) and its cultivation using elevated glucose concentrations represent an attractive technology for fast and efficient pDNA production and a valuable alternative to fed-batch cultivations of commercial strains.
Efecto del extracto de Yucca schidigera en el perfil bioquímico y hemático de cerdos en crecimiento y engorde.
Espinosa Mu?oz,Verónica; García Contreras,Adelfa del C; Herrera Haro,José G; álvarez Macías,Adolfo G; Estrada Barrón,Silvia G; Meza Cortes,Miriam;
Revista Científica , 2008,
Abstract: the effect of yucca schidigera an the hematological values of growing and fattening pigs was studied. thirty york x landrace x pietrain pigs (ylp) were assigned to three different treatments at random used for this research: t1, standard diet (sorghum-soybean); t2, standard diet + 120 g of de-odorase? and t3, standard diet + 120 g of amoprem?. the hematological values were evaluated in a blood sample with edta. moreover, the biochemical profile of the animals was determined (creatinine, urea, total protein, albumin, cholesterol, triglyceride, and glucose) with the blood serum. to analyze the hematic values an analysis of variance was used, and the differences between means were inspected using tukey′s test. in order to interpret the results of the hematological values, there were established reference values for the control treatment calculated by 95% confidence limits. the level of triglyceride (0.47, 0.32, and 0.33 mmol/l an t1, t2, and t3), cholesterol (1.39, 1.29, and 1.31 mmol/l) and urea (3.95, 3.84 and 3.67 mmol/l) in the growing pigs showed differences between treatments (p<0.05). in the fattening pigs, it was observed that the concentrations of triglyceride (0.36, 0.31 and 0.35 mmol/l), urea (4.61, 4.65 and 4.28 mmol/l) and total protein (5.50, 5.36 and 5.47 g/dl) decreased in the treatments when yucca schidigera was added in the diet (p<0.05). the hematological profiles in the growing pigs didn?t show differences (p>0.05); however, in the fattening pigs there were differences (p<0.05) in hemoglobin (18.31, 20.04, and 20.62 g/dl) neutrophils (18.15, 27.15, and 25.40%) and monocytes (13.45, 7.00, and 8.50%). so the conclusion is that the levels of cholesterol, triglyceride, and urea decreased when adding the yucca schidigera extract in the diet, even when these values are found in the rank of reference obtained in the present study.
La popularidad de las especies. Las diez principales
Barrón, Vidal,Barrón, Carlos
Revista Espa?ola de Documentación Científica , 2005,
Abstract: A measure of animal, plant and mineral species popularity can be easily obtained from the information available in the Science Citation Index. We used the title, abstract and keyword strategy in this index to find how many times the name of a species had been included in papers published since 1945 to the present. A good fitting of the variation of the number of citations with the rank was obtained with a linearizable and higher trascendental function y = a x–b e–cx. We also show the species hit parade . The first ten species all have some anthropic character. La base de datos Science Citation Index nos permite fácilmente obtener una medida de la popularidad científica de las especies animales, plantas y minerales. Utilizando en esta base de datos la estrategia de búsqueda en título, resumen y palabras clave hemos cuantificado cuántas veces ha sido incluido el nombre de una especie en los artículos publicados desde 1945 hasta nuestros días. La variación del número de citas con respecto al orden que ocupan en el ránking sigue una función altamente trascendente: y = a x–b e–cx. En este ránking, las 10 especies más citadas tienen todas un fuerte carácter antrópico.
CICLO DE CONVERSIóN DE EFECTIVO EN LAS GRANDES EMPRESAS DE COMERCIO AL DETAL EN COLOMBIA (1998-2002)
MORENO MEZA,NéSTOR;
Estudios Gerenciales , 2004,
Abstract: this paper discusses the size and financial effects of the cash conversion cycle (ccc) for a sample of five general retailers operating in the colombian market during the period 1998- 2002. the concept of cash conversion cycle was proposed by richards and laughlin (1980) in order to improve the analytical treatment of liquidity in business; the cycle is calculated by combining three accrual-based turnover ratios : days sales outstanding, days inventory, and days payable. data from the financial statements of the sample of such retailers (almacenes exito-cadenalco, carulla-vivero, supertiendas y droguerías olímpica, la 14 y carrefour) show a significant effect of days payable (or trade credit) on financial leverage, liquidity and short-term cash requirements.
El patrón de los flujos de inversión extranjera directa en los países de América Latina (1991-2005)
Moreno Meza,Néstor;
Pensamiento & Gestión , 2008,
Abstract: this paper discusses the pattern of flows of net foreign direct investment for the long run (1991-2005) in 18 countries of the latin american region and tests the hypothesis of positive relationship between the size of gross domestic product and the flows of net fdi. based on the analysis of global trends and other factors, the ordinary linear regression of the figures available for the long term period shows a high degree of correlation between the size of the gross domestic product and the flows of net direct investment by country. in the case of colombia the long term performance is better than expected -in spite of the political risk involved-, but the failure in developing new areas for export-oriented foreign direct investment, due the lack of good infrastructure, remains a major constraint for growth based on investment projects that enhance economic efficiency and competitiveness.
Evaluación de la nutrición mineral del níspero (Manilkara achras Miller Fosberg) en plantas jóvenes cultivadas en contenedores
Meza,N; Pire,R;
Revista de la Facultad de Agronomía , 2008,
Abstract: in the tropics, the mineral nutrition of young fruit plants study is important due to the fast initial growth. with the purpose of knowing aspects of mineral nutrition of sapodilla plants, the concentrations of the main macro and micronutrients on leaves, stems and roots of one and two-year old plants grown in containers was determined. a split plot design with factorial arrangement of treatments (2 ages x 3 organs) and six replicates was used with the exception of calcium; one-year old plants had significantly higher foliar concentrations than the two years old plants. in case of stem and root, the nutrient concentrations showed similar behavior to those of leaves even though differences were greater for potassium and calcium. in general, foliar concentrations were in the range of sufficiency. leaf was the plant organ that accumulated the higher levels of nitrogen and calcium, the stem showed the highest level of phosphorus, while the rest of the nutrients were mainly stored in root. regardless of the plant tissue, the most absorbed macronutrients were ca, p and n, leaving mg and p in the lower levels. the most absorbed micronutrient was fe followed by zn and to a lesser extent by mn and c. it is concluded that there is a considerable variation of nutrient levels concentration according to plant age and the analyzed tissue.
El patrón de los flujos de inversión extranjera directa en los países de América Latina (1991-2005)
Néstor Moreno Meza
Pensamiento & Gestión , 2008,
Abstract: Este informe de investigación estudia el patrón de los flujos de inversión extranjera neta para el largo plazo (1991-2005) en los 18 países de América Latina y examina la validez de la hipótesis que relaciona positivamente el tama o del producto interno con la inversión extranjera directa. Basado en el análisis de las tendencias globales y otros factores de largo plazo, la regresión lineal simple de las variables muestra un alto grado de correlación entre el tama o de las economías domésticas (PIB) y el tama o de los flujos netos de inversión extranjera directa por país. En el caso de Colombia, los resultados son mejores de lo esperado -a pesar del riesgo político involucrado-, pero el fracaso en los desarrollos de nuevas áreas de exportación, originado en la falta de adecuada infraestructura, plantea un obstáculo mayor para el crecimiento sostenido basado en proyectos de inversión que mejoren la eficiencia de la economía y la competitividad This paper discusses the pattern of flows of net foreign direct investment for the long run (1991-2005) in 18 countries of the Latin American Region and tests the hypothesis of positive relationship between the size of gross domestic product and the flows of net FDI. Based on the analysis of global trends and other factors, the ordinary linear regression of the figures available for the long term period shows a high degree of correlation between the size of the gross domestic product and the flows of net direct investment by country. In the case of Colombia the long term performance is better than expected -in spite of the political risk involved-, but the failure in developing new areas for export-oriented foreign direct investment, due the lack of good infrastructure, remains a major constraint for growth based on investment projects that enhance economic efficiency and competitiveness.
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