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Search Results: 1 - 10 of 216977 matches for " Ramírez-Pérez "
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Requerimiento de fósforo de los Microorganismos ruminales: una revisión
Ramírez-Pérez,Aurora H; Meschy,Fran?ois;
Interciencia , 2005,
Abstract: the effect of phosphorus (p) on microbial activity and the use of nutrients by the ruminant are described. recent recommendations on mineral feeding reduce dietary p concentration. phosphorus supply must satisfy the requirements of ruminal microbes in order to ensure an adequate fermentation process. microbial p requirements are greater for cellulose breakdown than for protein synthesis (6.9 vs 4.3g available p/kg of fermentable organic matter in the rumen). phosphorus utilization by bacteria depends on its dietary content, availability, and endogenous contribution through saliva, as well as on the microbial response to p variations in the ruminal content. due to these complexities, further investigation is needed. furthermore, any decrease in excreted p because of a reduction in its intake will have a positive effect on the environment.
Revisión del estado del arte de IR-Ultra-Wideband y simulación de la respuesta impulsiva del canal IEEE 802.15.4a
Suárez-Páez,Julio; Llano-Ramírez,Gonzalo;
Ingeniería y Ciencia , 2010,
Abstract: this paper reviews the state of the art of the technology based in channels of ultra wide band (uwb ultra-wideband) focusing on its regulation, standardization, basic applications, ieee 802.15.4a channel model and simulation of the impulsive response of this type of channel. also, it aims to introduce the reader to the technologies based on ir-uwb channels and the parameters for modeling and simulation of ieee 802.15.4a uwb channel.
Reacción en cadena de polimerasa (PCR) para detectar formas infectivas de Onchocerca volvulus en Simulium metallicum s.l. (Diptera: Simuliidae), en áreas endémicas de Venezuela
Fernández,Alexis; Ramírez-Pérez,Jaime; Shuler,Harland; Rodríguez,Noris;
Boletín de Malariología y Salud Ambiental , 2008,
Abstract: we present the results obtained after a parasitological study carried out in three onchocerciasis endemic areas located in the north-central and north- oriental foci in venezuela. during one year, adult females of simulium spp. were captured when landing on human attractants along rivers and in the proximity of houses where onchocerciasis cases had been detected. a total of 95,251 black flies were captured, from this total, only 0.05% were identified as s. exiguum s.l. and the rest were simulium metallicum s.l. all the specimens were submitted to mechanical disruption for head and body separation. the heads were grouped in pools of 50 for genomic dna extraction. the dna was used to evaluate the natural infectivity by o. volvulus using the polymerase chain reaction technique with species specific oligonucleotides. the prevalence of infective flies, was calculated using the poolscreen program; the results indicated a positivity of 9/10,000 flies for the locality of la cuesta (north-eastern focus, anzoátegui state), followed for santa rosa (north- central focus, carabobo state) with a prevalence of 5/10,000, and finally la carapa (north-eastern focus, monagas state) with the lowest index (3/10,000) of infectivity. these results are demonstrating the utility of the technique for large scale entomological studies and the specific detection of o. volvulus, infective larvae, the causal agent of human onchocerciasis.
Edad y crecimiento del conejo (Caulolatilus affinis) en la región central del Golfo de California
Ramírez-Pérez, JS;Melo-Barrera, FN;Ayala-Bobadilla, LE;
Ciencias marinas , 2011,
Abstract: age, growth, and the length-weight relationship were estimated for the pacific golden-eye tilefish caulolatilus affinis captured by the artisanal fishery in the central region of the gulf of california. the size and weight structure differed between sexes, males being larger and heavier than females; however, differences in the length-weight relationship were not detected and the slope value (b = 2.66) showed that it was a negative allometric relationship. the youngest and oldest organisms were 3 and 21 years old, respectively. the age structure showed differences between sexes, males being more abundant at older ages and females at younger ones. the dominant age group for females was 11 years old and for males, 16 years old. the von bertalanffy growth model fitted adequately the mean size and age data; the model parameters were l∞ = 432.32 mm total length, k = 0.232 mm yr-1, and t0 = 0.164 yr for males, and l∞ = 422.99 mm total length, k = 0.245 mm yr-1, and t0 = -0.095 yr for females. differences in individual growth and growth rate between males and females were not detected. according to the age structure and growth pattern, c. affinis is a slow-growing, medium-lived species. our results suggest that c. affinis is underexploited in the central gulf of california because it is a non-target species.
Diet-Related Buccal Dental Microwear Patterns in Central African Pygmy Foragers and Bantu-Speaking Farmer and Pastoralist Populations
Alejandro Romero, Fernando V. Ramírez-Rozzi, Joaquín De Juan, Alejandro Pérez-Pérez
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0084804
Abstract: Pygmy hunter-gatherers from Central Africa have shared a network of socioeconomic interactions with non-Pygmy Bantu speakers since agropastoral lifestyle spread across sub-Saharan Africa. Ethnographic studies have reported that their diets differ in consumption of both animal proteins and starch grains. Hunted meat and gathered plant foods, especially underground storage organs (USOs), are dietary staples for pygmies. However, scarce information exists about forager–farmer interaction and the agricultural products used by pygmies. Since the effects of dietary preferences on teeth in modern and past pygmies remain unknown, we explored dietary history through quantitative analysis of buccal microwear on cheek teeth in well-documented Baka pygmies. We then determined if microwear patterns differ among other Pygmy groups (Aka, Mbuti, and Babongo) and between Bantu-speaking farmer and pastoralist populations from past centuries. The buccal dental microwear patterns of Pygmy hunter-gatherers and non-Pygmy Bantu pastoralists show lower scratch densities, indicative of diets more intensively based on nonabrasive foodstuffs, compared with Bantu farmers, who consume larger amounts of grit from stoneground foods. The Baka pygmies showed microwear patterns similar to those of ancient Aka and Mbuti, suggesting that the mechanical properties of their preferred diets have not significantly changed through time. In contrast, Babongo pygmies showed scratch densities and lengths similar to those of the farmers, consistent with sociocultural contacts and genetic factors. Our findings support that buccal microwear patterns predict dietary habits independent of ecological conditions and reflect the abrasive properties of preferred or fallback foods such as USOs, which may have contributed to the dietary specializations of ancient human populations.
Lesión con radiofrecuencia percutánea en el manejo de la neuralgia trigeminal idiopática multitratada
Picos,G. I.; Hernández-Santos,J. R.; Tenopala,S.; Torres,J. C.; Ramírez-Pérez,M.;
Revista de la Sociedad Espa?ola del Dolor , 2004,
Abstract: objective: to demonstrate the efficacy of the percutaneous radiofrequency in the management of the idiopathic trigeminal neuralgia, as well as fewer numbers of complications observed with this technique. material and methods: we recluted 10 patients with idiopathic trigeminal neuralgia with previous unfavorable outcome with standard pharmacological and interventional treatment. all the procedures were performed with fluoroscopic control using hartel′s technique. all patients underwent a radiofrequency lesion in an impedance range between 200 and 300 ohms, within a time of 60 minutes and within a temperature of 65, 75 y 90 °c, divided in three stages. we used visual analogue score for analysis, and we looked for complications within a median follow up of 12 months. results: we found a total efficacy of 70% with a confidence interval of ± 0.28% and p<0.05, besides, 20% of the patients accomplished a good outcome through a second percutaneous radiofrequency procedure. we didn’t have a response in 10% of the patients. in the visual analogue score evaluation, we found a decrement in the results, that was statistically significant, with a initial mean of 8.8 points versus final mean score of only 0.16 (p< 0.05). there was also a treatment reduction in regard to anticonvulsant and opiates. the complications recorded were: hypoesthesia of the treated branches in 90% of the patients, corneal hypoesthesia in 10%, earache in 70%, and hypoacusia in 10%. conclusion: idiopathic trigeminal neuralgia with unfavorable response regardless, previous multiple treatments, still has a good outcome using percutaneous radiofrequency lesion procedure, and also can be observed a reduced drug use and fewer complications.
Identit tskonstruktion bei Konvertit(inn)en der chilenischen Pfingstgemeinde Identity Construction of Converts to the Pentecostal Methodist Church of Chile Construcción de identidad en personas convertidas a la Iglesia Metodista Pentecostal de Chile
Víctor Hugo Masías-Hinojosa,Paola Andrea Ramírez-Pérez,María Inés Winkler-Müller
Forum : Qualitative Social Research , 2008,
Abstract: Dieser Artikel befasst sich mit der Identit tskonstruktion von Personen, die zur chilenischen Pfingstgemeinde (Iglesia Metodista Pentecostal de Chile, IMPCH) konvertiert sind. Hierzu wurden elf biografisch-narrative Interviews durchgeführt; die Auswertung erfolgte entlang der Methodologie der Grounded Theory. Die Ergebnisse legen nahe, dass sich die Identit tskonstruktion entlang von fünf Schlüsselkategorien vollzieht: Kontinuit t von Gotteserfahrung, Ver nderung als Sich-Gleichbleiben, Selbstdefinition in Relation zu dem Anderen (Gott), Identit t als Projekt (Teil von Gottes Gemeinschaft sein) und Transzendenz als Resultat des Apostolats. Diese Kategorien bilden eine Gesamtorganisation von ideologischen Botschaften, die mit dem Diskurs innerhalb der IMPCH korrespondieren. Die eigenen Befunde werden im Lichte der Ergebnisse anderer Studien diskutiert und es werden abschlie end einige praktisch-psychologische Vorschl ge gemacht. URN: urn:nbn:de:0114-fqs0801238 This paper explores the identity construction of people who have converted to the Pentecostal Methodist Church of Chile (Iglesia Metodista Pentecostal de Chile, IMPCH). Biographical-narrative interviews were conducted with eleven people converted to IMPCH, with analysis based on grounded theory methodology. The results indicate that personal identity is constructed by means of five key elements: the continuity of divine intervention, change in the sense of sameness, the definition of oneself in relation to the Other (God), identity as a project (being God's people), and transcendence as a result of an Apostolate life. Such elements have a loaded organization of ideological messages corresponding to the Pentecostal discourse. The results are contrasted with findings of other related investigations and conclude with some practical psychological proposals. URN: urn:nbn:de:0114-fqs0801238 El presente artículo trata sobre la construcción de identidad en personas convertidas a la Iglesia Metodista Pentecostal de Chile (IMPCH). Se realizó una entrevista biográfica-narrativa a 11 personas convertidas a la IMPCH, siguiendo el método de la Grounded Theory para el análisis de los relatos. Los resultados indican que la identidad personal estaría construida por medio de cinco anclajes; continuidad como producto de la intervención divina, el cambio en el sentido de la mismidad, la definición de sí en relación con el Otro (Dios), la identidad como proyecto (ser gente de Dios) y la trascendencia como producto de una vida de apostolado. Tales anclajes poseen una organización cargada de mensajes ideológicos correspo
Diversidad de frijoles nativos de diferentes regiones del estado de Puebla Native beans diversity of different regions from state of Puebla
Ana Rosa Ramírez-Pérez,Ramón Díaz-Ruiz,Carmen Jacinto-Hernández,Juan Alberto Paredes-Sánchez
Revista mexicana de ciencias agrícolas , 2012,
Abstract: El frijol común representa un cultivo básico en México con una gran variabilidad en sus características morfológicas. En estudios sobre la diversidad genética se han usado marcadores moleculares, entre los que se encuentran los RAPD. El presente trabajo tuvo como objetivo caracterizar mediante caracteres morfológicos, agronómicos, de calidad y marcadores RAPD, variedades de frijoles nativos cultivadas en diferentes comunidades del estado de Puebla. La extracción de ADN se realizó en una muestra de hojas jóvenes de las variedades sembradas bajo invernadero. Se utilizaron 7 iniciadores RAPDs de la serie OPERON Technologies. Las bandas polimórficas se codificaron por presencia y ausencia. Con el programa NTSYS pc 2.2 se generó un dendograma empleando el índice de similitud de Dice, con nivel de corte a un valor de 0.48, donde se definieron 13 grupos. Seis grupos estuvieron integrados por una variedad, 4 grupos por 2 variedades, 2 grupos por 3 variedades y un grupo formado por 7 variedades. Los grupos definidos se integraron por colores de grano distintos y coincidieron en otras características morfológicas como días a floración, tiempo de cocción y contenido de proteína. Common bean is basic crop in Mexico with great variability in its morphological characteristics. RAPD is among molecular markers, which have been used in studies about genetic diversity. The aim of this work was to characterize by morphological, agronomical, quality characters and RAPD markers the varieties harvested in different localities from state of Puebla. DNA extraction was made from sample of young leaves of varieties planted under greenhouse. 7 RAPDs starters from OPERON Technologies were used. Polymorphical bands were coded by presence and absence. With NTSYS pc 2.2 software dendrogram was created using Dice's similarity index, with cut level at value of 0.48 where 13 groups were defined. Six groups were comprised by single variety, 4 groups by 2 varieties, 2 groups by 3 varieties and one group by 7 varieties. The defined groups were comprised by different grain colors and coincided in other morphological characteristics like days to flowering, cooking time and protein content.
Características físico-químicas de las dunitas serpentinizadas de la región de Moa-Baracoa (zonas Amores y Miraflores)
José A. Pons-Herrera,Carlos A. Leyva-Rodríguez,Gleurides Rodríguez-Martínez,María C. Ramírez-Pérez
Minería y Geología , 2000,
Abstract: Los principales resultados de la caracterización físico-química y mineralógica de las dunitas serpentinizadas de las zonas de Amores y Miraflores en la región de Moa-Baracoa, se exponen en este trabajo. Se demuestra la presencia de minerales del grupo de la serpentina, principalmente antigorita, debido al proceso de serpentinización que ha afectado a estas rocas, y su transformación en fase forsterita luego de su calentamiento. Estos aspectos revisten especial importancia para las investigaciones que en la actualidad se realizan con estas litologías para su empleo como material refractario
Fisheries Management under Ecological Interdependence: The Case of European Hake and Blue Whiting Fishery  [PDF]
Marcos Pérez-Pérez, M. Dolores Garza-Gil, Manuel Varela-Lafuente
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.88036
Abstract: In mixed fisheries where there is an increased ecological interdependence between two or more target species, the possibilities of fishing these species must be determined jointly, since catches of one species will impact the natural growth not only of that species but of the others, as well. The objective of this paper is to develop a predator-prey model for two major species caught by the EU fishing fleet on European Union fishing grounds. The predator and prey’s population dynamics follow the Lotka-Volterra equation and are assumed to be logic-based, and a lineal interaction between the predator and prey populations is assumed. Optimal single owner multispecies fishery management is analysed, and the applied model is solved, obtaining the equilibrium value of biomasses, catches, and net benefits of the mixed fishery. The results show that the MSY of the predator is higher than that estimated by ICES, while MSY for prey is lower. The sensitivity analysis of the results reveals that the biomass levels of both species decrease as the discount rate increases, while catches increase.
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