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Search Results: 1 - 10 of 218584 matches for " Nelson Pérez "
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A Review on Some Chemical Engineering and Microbiological Aspects Considered in the Production of Highly Concentrated Probiotic Cultures and Bacteriocins by Lactococci and Lactobacilli
Nelson Pérez Guerra
ISRN Chemical Engineering , 2012, DOI: 10.5402/2012/836381
Abstract: The main purpose of this work is to give an overview on the chemical engineering aspects related with the production of probiotic cultures and bacteriocins. Firstly, some evidence of the potential of different Lactococci and Lactobacilli strains for prevention or treatment of different human diseases, or as growth promoters in farm animals is given. In addition, examples of different commercial dietary supplements containing probiotic lactoccocci and lactobacilli in combination or not with other probiotic bacteria are presented. Secondly, the main factors (cultivation method, culture media, and media composition) affecting the production of bacteriocins by lactoccocci and lactobacilli strains are showed. Examples of modelling procedures developed to describe the production of higher concentrations of biomass and bacteriocins in fed-batch cultures subjected or not to successive alkalizations are summarized. Finally, the corresponding mass balance equations performed in the latter cultures are presented to calculate the volumes of feeding substrates and the concentrations of nutrients (lactose, glucose, proteins, nitrogen, and phosphorous) added to the fermentation medium, as well as the concentrations of biomass and products in the fermentor just after each feeding. 1. Main Characteristics of Probiotics Probiotics are viable microorganisms that, once ingested in sufficient amounts, exert health-promoting effects in humans and animals by assisting in the establishment of an intestinal population which is beneficial to the host entity and antagonistic to harmful bacteria [1–4]. This beneficial effect is commonly related with the elimination of pathogens by stimulating the immune system, by colonizing the gut in large numbers (competitive exclusion), and/or by the production of antimicrobial substances, including organic acids and bacteriocins [5, 6]. Thus, since the extensive use of antimicrobials (e.g., antibiotics and silver sulphadiazine) could produce adverse reactions and side effects [7, 8], the interest has been focussed on the use of probiotics for preventing or treating different human diseases [1, 4] and for improving the performance parameters of farm animals. These probiotics can play an important role in immunological, digestive, and respiratory functions in humans [9] and can improve the body weight gain and feed conversion in farm animals [2, 3]. The probiotic strains must be: (i) safe, noninvasive, nonpathogenic, nontoxic, and noncarcinogenic; (ii) resistant to gastric acidity and bile toxicity, which is an important characteristic for
Soporte computacional para administración integrada de redes y servicios
Pérez Castillo José Nelson
Ingeniería e Investigación , 1996,
Abstract: Este artículo contextualiza la problemática actual de la administración de redes de comunicaciones considerando las profundas repercusiones, tanto de la internacionalización de la economía como del ritmo impetuoso del avance tecnológico sobre el sector teleinformático y la calidad en la prestación de los servicios de comunicaciones. Rese a someramente las actividades de los distintos frentes de estandarización; en particular la ISO, la ITU- T y la Internet. Se muestran, entonces, las características del soporte computacional para el desarrollo de aplicaciones, se alando los servicios de comunicaciones, interfaz gráfica y bases de datos teniendo en cuenta la naturaleza distribuida de la administración de redes. Finalmente, se muestran los atributos generales de las herramientas de desarrollo disponibles en la actualidad.
Ensayo de insecticidas en la lucha contra el estado adulto de Pachnaeus litus(Germar)en condiciones de laboratorio y de campo.
Felipe Pérez,Nelson Medina
Avanzada Científica , 2010,
Abstract: Se ensayaron los insecticidas Carbaryl 85% PH, Volaton 50% EC, Hostation 50 % EC, Tokutlion 50 % EC y Lebaycid 50% EC,contra el estado adulto de P. litus. En condiciones de laboratorio se emplearon dos métodos (papel de filtro impregnado con las soluciones tóxicas y jaulas de malla plástica con postura de cítricos en el interior).En condiciones de campo se cubrieron las ramas de las plantas seleccionadas con mallas plásticas.La efectividad de los insecticidas empleados se determina mediante la fórmula de Abbout. El Tokutlion presenta mejor efecto biológico que los demás productos ensayados.
DISE O DE PROTOTIPOS EXPERIMENTALES ORIENTADOS AL APRENDIZAJE DE LA OPTICA
Pérez Lozada, Eliexer,Falcón, Nelson
Revista Eureka sobre Ense?anza y Divulgación de las Ciencias , 2009,
Abstract: Se presenta un conjunto de prototipos experimentales para el aprendizaje de la óptica. Los prototipos fueron elaborados con materiales de bajo costo y de fácil adquisición, mejorados en sus dise os, validados por expertos y probados en el aula para su valoración. Con ellos se recreó una metodología sustentada en constructos y procesos que mejoró el logro de los alumnos, mostrando su pertinencia y efectividad para la ense anza de la óptica
A Review on Some Chemical Engineering and Microbiological Aspects Considered in the Production of Highly Concentrated Probiotic Cultures and Bacteriocins by Lactococci and Lactobacilli
Nelson Pérez Guerra
ISRN Chemical Engineering , 2012, DOI: 10.5402/2012/836381
Abstract:
Interoperabilidad entre los dominios de la arquitectura, ingeniería y construcción y los sistemas de información geográfica
Fredy Orlando Bello Pérez,José Nelson Pérez Castillo
Ingeniería y Universidad , 2012,
Abstract: El dominio de la arquitectura, ingeniería y la construcción se soporta en las clases base de la industria, para representar sus entidades. El dominio de los sistemas de información geográfica, utiliza el lenguaje de marcado geográfico para modelar sus entidades, que tienden a evolucionar hacia modelos tridimensionales. El problema central a tratar en el presente artículo; es la integración entre estos dos dominios. Se abordan las bases conceptuales, se muestran propuestas para su integración y se definen los hallazgos acerca de su interoperabilidad.
Estado actual de las tecnologías de bodega de datos y OLAP aplicadas a bases de datos espaciales
Abril Frade,Diego Orlando; Pérez Castillo,José Nelson;
Ingeniería e Investigación , 2007,
Abstract: organisations require their information on a timely, dynamic, friendly, centralised and easy-to-access basis for analysing it and taking correct decisions at the right time. centralisation can be achieved with data warehouse technology. on-line analytical processing (olap) is used for analysis. technologies using graphics and maps in data presentation can be exploited for an overall view of a company and helping to take better decisions. geographic information systems (gis) are useful for spatially locating information and representing it using maps. data warehouses are generally implemented with a multidimensional data model to make olap analysis easier. a fundamental point in this model is the definition of measurements and dimensions; geography lies within such dimensions. many researchers have concluded that the geographic dimension is another attribute for describing data in current analysis systems but without having an in-depth study of its spatial feature and without locating them on a map, like gis does. seen this way, interoperability is necessary between gis and olap (called spatial olap or solap) and several entities are currently researching this. this document summarises the current status of such research.
Servicio web inteligente para la clasificación de imágenes digitales utilizando conjuntos aproximados
Caicedo Caicedo,Julio César; Pérez Castillo,José Nelson;
Ingeniería e Investigación , 2010,
Abstract: integrating recent developments in service-orientated computing, web technologies and computational intelligence has facilitated the development of applications for solving complex problems in several fields of scientific and technological research. rough sets theory provides a solid theoretical background within the computational intelligence (ci) field for the qualitative reasoning re-quired for analysing datasets loaded with uncertainties due to the vagueness and lack of precision associated with them. this paper describes the development of an intelligent web service to process digital imagery, demonstrating the benefits of rough sets theory in dealing with the flexible supervised classification of the pixels associated with them.
Modelo de portal para el Laboratorio de Computación Grid
Monta?ez Torres,Sandra Neyid; Pérez Castillo,José Nelson;
Ingeniería y Universidad , 2008,
Abstract: in order to achieve significant progress in computer science, new and powerful solutions in the field of information technology are required; some of the current processes would not be possible without access to powerful computing resources. this investigation focused on creating a system for harnessing these resources in a distributed environment called a grid. the grid is based on the sharing of distributed computing resources for multiple purposes in a computational process. currently, researchers are required to understand some advanced concepts in order to incorporate all the advantages of grid architecture. the idea throughout this project was to create a portal oriented to researchers who wish to execute tasks using distributed resources, without their having to delve into the technical details of grid technologies. the first part of this article describes the basics for grid portals and the proposed model; the article subsequently emphasizes the components of the prototype including all relevant elements for modeling the portal, such as middleware, frameworks, web server, and portlets. following is a brief description of the results achieved throughout the project, including the satisfactory performance of the portal, with the conclusion that the execution of tasks using distributed resources through the portal takes considerably less time than with other methods, in addition to being more user-friendly. finally some significant recommendations for future work are identified.
Eficacia de la Inmunofluorescencia Indirecta para la Detección Temprana del Virus de Encefalitis Equina Venezolana en Cerebro de Ratones Lactantes
Aranguren,Francis; Obando,César; Pérez,Nelson; Hidalgo,Mayra;
Revista de la Facultad de Ciencias Veterinarias , 2006,
Abstract: the aim of this study was to standardize and evaluate the efficacy of the indirect immunofluorescent technique (iift) for early detection of venezuelan equine encephalitis virus (veev) antigen in the brain of suckling mice, using the complement fixation test (cft) as a comparison. viral antigen tc-83 was detected at 10, 12 and 26 hours post-inoculation (hpi), for p-676, lara-95 and tc-83 strains, respectively. the sensitivity of iift for lara-95 strain, was 89% at 24 hpi (non symptomatic period), when compared to 32% for cft, indicating that the low concentration of viral antigen during the early phases of the disease, can be detected with iift. the sensitivity of both techniques compared to the biological assay was 86% and 29% for iift and cft, respectively. at 36 hpi in mice with evident symptomatology, the sensitivity and specificity of both test was 100%. these results indicate that the iift is a valid and efficient test to evaluate out breaks of venezuelan equine encephalitis, in order to contributing to epidemiological surveillance of the disease.
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