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Search Results: 1 - 10 of 410391 matches for " Andrade Casta?eda Hernán Jaír "
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Demanda de mano de obra y rentabilidad de bancos forrajeros en Esparza, Costa Rica
Sánchez Sarmiento,Luz Yaneth; Andrade Castaeda,Hernán Jaír; Rojas Molina,Jairo;
Acta Agronómica , 2010,
Abstract: we made a financial analysis in order to assess the feasibility to invest in fodder banks as an alternative for supplementing animals in dual purpose systems during the dry season (125 days). models were constructed to compare cutting and carrying of perennial woody fodder banks (veranera) cratylia argentea + sugar cane (saccharum officinarum) and browsing fodder banks of leucaena leucocephala with two supplements: concentrates and chicken manure. the indicators used for the financial evaluation of the systems were net present value (npv) and internal return rate (irr). a sensitivity analysis was carried out with an increase in milk, concentrate and chicken manure and labor prices. we found that perennial fodder banks required in average 71.1 man labor year-1 for their management. financial analysis showed that they are profitable when compared to chicken manure (npv= us$ 362.2; irr=17%) and concentrates (npv: us$ 1953.9; irr=39%). fodder banks with leucaena required 13 man labor year-1 for their management.. they are profitable when compared to chicken manure (npv=us$1594.7; irr=21%) and with concentrates (npv=us$3619.6; irr=35%). the models were sensible to changes in milk production, reduction in price of chicken manure and concentrates and reduction both in the labor price and price of milk. in summary, fodder banks are a good alternative for supplementing animal in the dry season and an important source of employment in the region; nevertheless, the high cost of hired labor could limit their adoption.
Demanda de mano de obra y rentabilidad de bancos forrajeros en Esparza, Costa Rica
Sánchez Sarmiento Luz Yaneth,Andrade Castaeda Hernán Jaír,Rojas Molina Jairo
Acta Agronómica , 2010,
Abstract: En Esparza (Costa Rica) se evaluó la viabilidad de invertir en bancos forrajeros (BF) como alternativa de suplementación para vacas en sistema doble propósito durante la época seca (125 días). Se usaron como indicadores de rentabilidad el Valor Presente Neto (VPN) y la Tasa Interna de Retorno (TIR). Se realizó un análisis de sensibilidad para el incremento del precio de la leche, los concentrados, la gallinaza y la mano de obra. Los modelos se elaboraron comparando los BF de plantas le osas perennes de corte y acarreo de Cratylia argentea + ca a de azúcar (Saccharum officinarum) (BFC) y de ramoneo Leucaena leucocephala (BFL) vs. suplementos comerciales tipos concentrado y gallinaza. En los BFC se requirieron 71.1 jornales/a o y el análisis financiero indicó que son rentables al compararlos con la gallinaza (VPN = US$362.2, TIR = 17%) y concentrados (VPN = US$1953.9; TIR=39%). En BFL se requirieron 13 jornales/a o y fueron igualmente rentables en comparación con gallinaza (VPN = US$1594.7; TIR = 21%) y con concentrados (VPN = US$3619.6; TIR=35%). Los modelos fueron sensibles a la producción y cambios de precios en la leche, gallinaza, concentrados y el valor del jornal. Los BF son una buena alternativa para la suplementación de ganado en la época seca y una importante fuente de empleo en la región; sin embargo, los altos costos de la mano de obra contratada pueden limitar la adopción.
Identificación y tipificación de biotipos y serotipos de Yersinia enterocolitica
Elizalde Castaeda,Paulino; Díaz? Aparicio,Efrén; Hernández? Andrade,Laura; Jaramillo Arango,Carlos Julio;
Revista de Saúde Pública , 2001, DOI: 10.1590/S0034-89102001000400008
Abstract: objective: to assess the presence of yersinia enterocolitica in otherwise healthy pigs slaughtered for human consumption. methods: one hundred pharyngeal tonsils were sampled in a slaughterhouse in the state of mexico. the minimum sample size (n=100) was calculated based on a preliminary sample of 20 cases, which had 20% positive cases. the collected tonsil samples were inoculated in rappaport broth, and salmonella-shigella and mcconkey media. the biotyping identification process was based on biochemical and serological tests using o:3, o:8 and o:9 antisera. results: twenty-two isolates were obtained. most were biotype 1 (8 cases of o:3 and 8 cases of o:9), but 6 cases could not be serotyped. none of the isolates were of o:8 group. conclusions: this was the first time that y. enterocolitica serotypes were isolated from pig tonsils in mexico. its importance rely on the fact that the isolated serotypes are the most commonly found in public health problems.
Identificación y tipificación de biotipos y serotipos de Yersinia enterocolitica
Elizalde Castaeda Paulino,Díaz? Aparicio Efrén,Hernández? Andrade Laura,Jaramillo Arango Carlos Julio
Revista de Saúde Pública , 2001,
Abstract: OBJETIVO: Conocer la existencia de Yersinia enterocolitica en suínos visiblemente sanos y sacrificados para el consumo humano. MéTODOS: Fueron estudiadas 100 muestras de tejido linfático obtenidas en el momento del sacrifício, en un matadero del Estado de México. Fueron realizados muestreos pilotos de 20 casos, de los cuales 20% fueron positivos, permitiendo obtener una muestra estudiada (n=100). Las muestras colectadas de tejido linfático fueron acondicionadas para el aislamiento de Yersinia enterocolitica en caldo de Rappaport y en medio de cultivo de Salmonella-Shigella y MacConkey. Las identificaciones fueron efectuadas por medio de pruebas bioquímicas y serológicas, utilizándose en el caso los antisueros O:3, O:8 y O:9 para la biotipificación correspondiente. RESULTADOS: Fueron obtenidos 22 aislamientos tipificándose 8 serotipos pertenecientes al O:3 y 8 al O:9 correspondientes al biotipo 1; y, en 6 muestras no fue posible la serotipificación. No se encontró en el total de los aislados el serotipo O:8. CONCLUSIONES: En base en la metodología, se registró la presencia de Y. enterocolitica y sus serogrupos en tejido linfático de porcinos por la primera vez en México; esto es importante porque el patógeno y sus serotipos aislados están comprometidos con mayor frecuencia con problemas de salud pública.
Sound speed resolved by photoacoustic technique
Pérez Ruíz, S.J.;Alcántara Iniesta, S;Hernández, P.R.;Castaeda-Guzmán, R;
Revista mexicana de física , 2007,
Abstract: in this work a new method for measuring the speed of sound in materials is reported. this method uses the photoacoustic effect, which is the generation of sound waves by pulsed optical radiation incident on a material sample. the sound waves generated on the surface of the sample travel through the material and are detected with two piezoelectric sensors separated by a known distance. an appropriate processing of the photoacoustic signal permits the separation of the information of the generated longitudinal waves, of their reflections, as well as of other types of waves generated (shear, surface, etc). the advantages and disadvantages, of this method are discussed in comparison with standard methods.
Sound speed resolved by photoacoustic technique
S.J. Pérez Ruíz,S. Alcántara Iniesta,P.R. Hernández,R. Castaeda-Guzmán
Revista mexicana de física , 2007,
Abstract: En el presente trabajo se reporta una técnica novedosa para medir la velocidad del sonido en materiales. Este método de medición utiliza el efecto fotoacústico, que consiste en irradiar una muestra de material con pulsos cortos de radiación láser, registrando la onda acústica generada con dos sensores piezoeléctricos separados por una distancia conocida. Un procesamiento adecuado de la se al fotoacústica permite separar la información de las ondas longitudinales generadas, de sus reflexiones, así como de los frentes de onda de otro tipo de ondas generadas (cortantes, de superficie, etc.). Se discuten sus ventajas y desventajas frente a los métodos usuales.
Nation-Wide, Web-Based, Geographic Information System for the Integrated Surveillance and Control of Dengue Fever in Mexico
Juan Eugenio Hernández-ávila, Mario-Henry Rodríguez, René Santos-Luna, Veronica Sánchez-Castaeda, Susana Román-Pérez, Víctor Hugo Ríos-Salgado, Jesús Alberto Salas-Sarmiento
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070231
Abstract: Dengue fever incidence and its geographical distribution are increasing throughout the world. Quality and timely information is essential for its prevention and control. A web based, geographically enabled, dengue integral surveillance system (Dengue-GIS) was developed for the nation-wide collection, integration, analysis and reporting of geo-referenced epidemiologic, entomologic, and control interventions data. Consensus in the design and practical operation of the system was a key factor for its acceptance. Working with information systems already implemented as a starting point facilitated its acceptance by officials and operative personnel. Dengue-GIS provides the geographical detail needed to plan, asses and evaluate the impact of control activities. The system is beginning to be adopted as a knowledge base by vector control programs. It is used to generate evidence on impact and cost-effectiveness of control activities, promoting the use of information for decision making at all levels of the vector control program. Dengue-GIS has also been used as a hypothesis generator for the academic community. This GIS-based model system for dengue surveillance and the experience gathered during its development and implementation could be useful in other dengue endemic countries and extended to other infectious or chronic diseases.
Nuclear expression of Rac1 in cervical premalignant lesions and cervical cancer cells
Miguel A Mendoza-Catalán, Gema R Cristóbal-Mondragón, Jesús Adame-Gómez, Heidi N del Valle-Flores, José Coppe, Laura Sierra-López, Mirna A Romero-Hernández, Luz del Carmen Alarcón-Romero, Berenice Illades-Aguiar, Eduardo Castaeda-Saucedo
BMC Cancer , 2012, DOI: 10.1186/1471-2407-12-116
Abstract: Protein expression was analyzed by immunochemistry on 102 cervical paraffin-embedded biopsies: 20 without Squamous Intraepithelial Lesions (SIL), 51 Low- grade SIL, and 31 High-grade SIL; and in cervical cancer cell lines C33A and SiHa, and non-tumorigenic HaCat cells. Nuclear localization of Rac1 in HaCat, C33A and SiHa cells was assessed by cellular fractionation and Western blotting, in the presence or not of a chemical Rac1 inhibitor (NSC23766).Immunoreacivity for Rac1, RhoA, Tiam1 and beta-Pix was stronger in L-SIL and H-SIL, compared to samples without SIL, and it was significantly associated with the histological diagnosis. Nuclear expression of Rac1 was observed in 52.9% L-SIL and 48.4% H-SIL, but not in samples without SIL. Rac1 was found in the nucleus of C33A and SiHa cells but not in HaCat cells. Chemical inhibition of Rac1 resulted in reduced cell proliferation in HaCat, C33A and SiHa cells.Rac1 is expressed in the nucleus of epithelial cells in SILs and cervical cancer cell lines, and chemical inhibition of Rac1 reduces cellular proliferation. Further studies are needed to better understand the role of Rho-GTPases in cervical cancer progression.Cervical cancer is the second most common malignant neoplasia affecting woman worldwide. Infection with High-Risk Human Papillomavirus (HR-HPV) is considered the main risk factor for developing cervical cancer and its precursor lesions [1-3]. Development of cervical Low-grade Squamous Intraepithelial Lesions (L- SIL) and High-grade Squamous Intraepithelial Lesions (H-SIL), and progression to invasive carcinoma, are associated with alterations in the regulation of several cellular processes such as cell cycle progression, apoptosis, and DNA repair [2,4,5]. The HR-HPV oncoproteins E6 and E7 are responsible for many of these alterations, they act by binding to, and/or modifying the expression/activity of a growing number of cellular proteins [6], including p53 [7], pRb [8], p21 [9,10], and p27 [11,12]. Rho-GTPases
Hysteresis in Pressure-Driven DNA Denaturation
Enrique Hernández-Lemus, Luz Adriana Nicasio-Collazo, Ramón Castaeda-Priego
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033789
Abstract: In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.
Estudio Morfométrico del Nervio óptico de Tiburoncito (Ariopsis seemanni) Morphological Study of Tete Sea Catfish (Ariopsis seemanni) Optic Nerve
Diana Carolina Castaeda Cortés,Oswaldo Tovar Bohórquez,Hernán Hurtado Giraldo
International Journal of Morphology , 2013,
Abstract: En peces, el nervio óptico es el encargado de transportar la información integrada por las células ganglionares de la retina hacia el tectum óptico, para que se generen imágenes acerca del entorno. El objetivo de este trabajo es describir morfométricamente el nervio óptico del tiburoncito (Ariopsis seemanni), para lo cual se utilizó la Microscopía óptica de Alta Resolución (MOAR), realizando cortes a 1 micra de espesor. El nervio óptico de A. seemanni presenta fibras mielínicas de diverso calibre, acompa adas de oligodendrocitos y astrocitos. El nervio está cubierto por las meninges, que presentan vasos sanguíneos y adipocitos. El nervio tiene un área total de 179604 ± 30163 μm2, diámetro de 478 ± 42 μm y un número total de fibras mielínicas de 22848 ± 4350, de las cuales la mayoría tiene un tama o peque o, que puede estar relacionado con una velocidad de conducción baja. The optic nerve carries out the information integrated by retinal ganglion cells towards the optic tectum, so that surrounding environment images are generated. The main goal of this paper is to describe morphometricaly the Tete sea catfish (Ariopsis seemanni) optic nerve, using high resolution optical microscopy (HROM), on 1 micron thick sections. A. seemanni optic nerve does present myelinated nerve fibers, accompanied by oligodendrocytes and astrocytes. The nerve is covered by the meninges, with blood vessels and adipocites. The nerve has a transversal area of 179,604 ± 30163 mm2, a diameter of 478 ± 42 mm and 22848 ± 4350 myelinated fibers, most are small in size, which may be related to a low conduction velocity.
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