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Search Results: 1 - 10 of 194798 matches for " CHARLOTTE E. GONZáLEZ-ABRAHAM "
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Ecorregiones de la península de Baja California: Una síntesis
González-Abraham, Charlotte E.;Garcillán, Pedro P.;Ezcurra, Exequiel;,;
Boletín de la Sociedad Botánica de México , 2010,
Abstract: the biological singularity of the baja california peninsula has captured the attention of naturalists since long time ago. as result, a rich variety of ecological and biogeographical interpretations have been proposed. they share a common framework, but at the same time show disagreement. an exhaustive review of published literature was done to identify which ecoregions or transition zones show disagreement. we submitted the discordant transition zones to the analysis of regional experts during a workshop, and with the help of a geographical information system we generated decisions by consensus for the majority of discussed zones. reults are shown in a map of ecoregions of the baja california peninsula, as a synthesis of the long time effort of study and analysis developed by individuals and institutions on the natural scenario of the baja california peninsula.
Boletín de la Sociedad Botánica de México , 2010,
Abstract: La singularidad biológica de la península de Baja California ha capturado el interés de los naturalistas por largo tiempo. Fruto de ello ha sido la publicación de una rica variedad de interpretaciones geográficas de su escenario ecológico y biogeográfico. Aunque coincidentes en un marco común general, presentan también numerosas discrepancias. En este trabajo se revisa exhaustivamente la literatura publicada sobre el tema con el objeto de identificar las fronteras o zonas de transición que presentan mayor diversidad o discrepancia. Se sometió el diagnóstico al examen y discusión de un taller de expertos, el cual contó con el apoyo de un sistema de información geográfica, generando decisiones consensuadas. Los resultados se presentan en un mapa de regiones ecológicas de la península de Baja California como una síntesis del estudio e interpretación sobre las ecorregiones naturales de la península de Baja California.
Determinación de los principales parámetros de calidad que afectan la cosecha mecanizada de arroz
Miranda Caballero,Alexander; Iglesias Coronel,Ciro E; Herrera González,Erwin; Abraham Ferro,Nathali; Castells Hernández,Santiago;
Revista Ciencias T??cnicas Agropecuarias , 2010,
Abstract: the present paper has as objective to analyze quality parameters that affect the mechanical harvest of the seed of rice, carried out by the new holland l521 rice harvester machine, under the conditions of work of the rice enterprise "los palacios" the cropper's technological parameters were evaluated in function of the quality of the harvested product, such as: seed entirely, peeled broken and content of sludges and total losses. the results obtained for the studied parameters indicate that for the new holland l521 rice harvester machine the behavior of the grain peeled y/o broken in the five observed different agricultural yields took values of 5,2-6,4% and the content of sludges was among 8,3-9,6%, being both parameters above the established limits, influencing mainly in this aspect the bad regulation of the organs of it thrashes, the speed work and the bad training of the operators. the application of these results allows him to the rice enterprise "los palacios to diminish the losses during the crop decreased the losses of 206 kg/ha up to 85 kg/ha, what represents an economic effect of $316 202.04 cuban pesos and at the same time allows to stop to invest approximately for the purchase of the rice shell to be processed for our population's feeding 184 793.4 usd.
Chemical Composition of Hexane Extract of Citrus aurantifolia and Anti-Mycobacterium tuberculosis Activity of Some of Its Constituents
Nallely E. Sandoval-Montemayor,Abraham García,Elizabeth Elizondo-Trevi?o,Elvira Garza-González,Laura Alvarez,María del Rayo Camacho-Corona
Molecules , 2012, DOI: 10.3390/molecules170911173
Abstract: The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), a-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25–50 mg/mL), 1 (MICs = 50–100 mg/mL), palmitic acid (MICs = 25–50 mg/mL), linoleic acid (MICs = 50–100 mg/mL), oleic acid (MICs = 100 mg/mL), 4-hexen-3-one (MICs = 50–100 mg/mL), and citral (MICs = 50–100 mg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.
Estudio comparativo entre diferentes esquemas de administración de 2 dosis con la vacuna cubana antihepatitis B
González-Griego,Martha de J.; Cinza,Zurina; Ortega,Abraham; Gali,María M.; Santoyo,María E.; García,Gerardo; Delahanty,Aurora;
Revista Cubana de Medicina Tropical , 1998,
Abstract: a controlled clinical trial, corresponding to stage 2, was conducted in a population of sound adult males aged 18-23 to evaluate the immunogenecity of 5 schedules of cuban vaccine against hepatitis b (cheberbiovac-hb). 5 groups were studied: i (control group 0, 1 and 6 months), ii (0 and 2 months), iii (0 and 4 months), iv (0 and 6 months), and v (0 and 8 months). the results showed no significant differences as regards the percentaje of seroprotection of any of the groups of 2 doses compared with the control of 3 doses. it is concluded that between the first and the second dose there may be a period of time from 2 to 6 months with no need to reinitiate the schedule. this information will serve as a basis for a population based study to determine which schedule is the best to be used.
Evaluación de la vulnerabilidad natural del acuífero freático en la cuenca del río Laja, centro-sur de Chile
González,Ljubow N; González,Abraham; Mardones,María;
Revista geológica de Chile , 2003, DOI: 10.4067/S0716-02082003000100001
Abstract: natural vulnerability evaluation of the the río laja basin phreatic aquifer, central-southern chile.the natural vulnerability of the phreatic aquifer of the hydrographic basin of the laja river was evaluated, by means of the determination of the vertical hydraulic resistance, using the 'aquifer vulnerability index' (avi) that allows to determine the infiltration speed from the pollutants when flowing through different soils horizons. the analysis of the tendencies of behavior of the contents of nitrates, phosphates, chlorides, sulfates and total dissolved solids, in the groundwater allows to establish a correlation between avi and source-aquifer contamination in the areas of different soil uses. the behavior of the different solutes in the groundwater is similar, with a tendency to increase from the precordillera andina towards the cordillera de la costa. the highest concentrations are found at the contact of the depresión central with the cordillera de la costa, where the risk of contamination, according to avi is moderate to high and very high. this indicates that the sandy soils of medium-fine texture, with low content of clay material provide a low degree of protection for the aquifer, since they have lower reserves of organic matter and sulfur available for sorption of phosphates and denitrification. also, a high water table reduces the attenuation capacity of these soils and it facilitates the transport of the pollutants of agricultural origin towards the groundwater. on the contrary, the agricultural pollutants are less concentrated in the groundwater linked to sandy soils of coarse and medium texture, with higher contents of clay, where the capacity to attenuate pollutants is related to larger contents of sulfur available and organic matter sorptive/labile, as well as by the greater depth of the groundwater level.
Evaluación de la vulnerabilidad natural del acuífero freático en la cuenca del río Laja, centro-sur de Chile
Ljubow N González,Abraham González,María Mardones
Revista geológica de Chile , 2003,
Abstract: Se evaluó la vulnerabilidad natural del acuífero freático de la cuenca hidrográfica del río Laja, mediante la determinación de la resistencia hidráulica vertical, empleando la metodología de 'Aquifer Vulnerability Index' (AVI), que permite determinar la velocidad de infiltración de los contaminantes al pasar el flujo del agua por los distintos horizontes de suelos. El análisis de las tendencias de comportamiento de los contenidos de nitratos, fosfatos, cloruros, sulfatos y sólidos totales disueltos, en el agua subterránea permiten establecer una correlación entre AVI y la fuente-contaminación acuífera en las áreas de diferentes usos del suelo. El comportamiento de los diferentes solutos en el agua subterránea es semejante, con una tendencia de incremento desde la Precordillera Andina hacia la cordillera de la Costa. Las concentraciones mayores se presentan en el contacto de la depresión Central con la cordillera de la Costa, donde el riesgo de contaminación, según AVI es moderadamente alto a muy alto. Esto indica que los suelos arenosos de textura media-fina, con escaso contenidos de material arcilloso proporcionan un bajo grado de protección para el acuífero, puesto que tienen menores reservas de materia orgánica y sulfuro disponible para sorción de fosfatos y denitrificación; además, los niveles freáticos altos, reducen la capacidad de atenuación propia de dichos suelos y facilitan el transporte de los contaminantes de origen agrícola hacia las aguas subterráneas. Por el contrario, los contaminantes agrícolas están menos concentrados en el agua subterránea relacionada con los suelos arenosos de textura gruesa y media, con mayor contenido de material arcilloso, donde la capacidad para atenuar contaminantes está relacionada con los mayores contenidos de sulfuro disponible y materia orgánica sorbible/lábil, así como por la mayor profundidad del nivel del agua subterránea. Natural vulnerability evaluation of the the río Laja basin phreatic aquifer, central-southern Chile.The natural vulnerability of the phreatic aquifer of the hydrographic basin of the Laja river was evaluated, by means of the determination of the vertical hydraulic resistance, using the 'Aquifer Vulnerability Index' (AVI) that allows to determine the infiltration speed from the pollutants when flowing through different soils horizons. The analysis of the tendencies of behavior of the contents of nitrates, phosphates, chlorides, sulfates and total dissolved solids, in the groundwater allows to establish a correlation between AVI and source-aquifer contamination in the areas of different so
González,Fredy E;
Investigación y Postgrado , 2002,
Abstract: this research reports ten basic actions which a student must apply if she /he wishes to succeed in trying to solve a mathematics problem with a text. "the successful problem solver decalogue" is a useful heuristic tool to help students in carrying out intellectually demanding tasks (iet). the "commandments" of the decalogue are the following: (1) to know the methodologies and techniques of problem solving. (2) to have an organized and sequential scheme which can guide the achievement of the solution. (3) to understand the problem statement. (4) to know the different steps which must be put into action in order to look for a solution. (5) to consider the context of the problem. (6) to make a careful review of the problem data. (7) to estimate the problem difficulty; (8) to make a strict and careful follow-up of all the factors related to the problem; (9) to devise a plan, a well defined strategy which leads to the solution; (10) to consider that not all the problems have the same structure. it is recommended to set the "commandments" of this decalogue into practice and to conduct studies which confirm its benefits as well as its possible enhancement.
La dinámica P2MA una opción didáctica frente a la ense?anza tradicional de la matemática
González,Fredy E.;
Investigación y Postgrado , 2003,
Abstract: this paper presents a didactic proposal coming from a piece of research performed by this author and a group of mathematic student teachers. the limitations of the traditional mathematic teaching and learning process becomes the context for creating new didactic models. this paper presents a review of the ontological, pedagogical and epistemological perspectives held by traditional mathematic teaching. it also presents a socio cognitive perspective of learning, associated with emergent ideas on mathematic learning. from there, this author propose the dynamic p2ma (teacher, problem, mathematic, student) as an alternative for the mathematic teaching and learning process. this proposal is based in: (a) problem solving, (b) pupil development of consciousness from his own cognitive behavior, and (c) mathematic as a special way of thinking in class, as a community for producing and socializing mathematical knowledge.
Observaciones tecnificadas y comparabilidad en ciencias
González, Carlos E;
Andamios , 2007,
Abstract: in this paper, i criticize the notion of incommensurability between scientific theories proposed by kuhn and i put forward a form of comparability based on what i call technified observations as a way to avoid the problem of theory-laddenness produced by un-translatability between theories. i develop three criticisms to the notion of translation that underlies the kuhnian project and to the use of the term incommensurability to refer to this form of lack of isomorphism. i also suggest a way in which progress in science is possible. finally, i point out some consequences this proposal has for the philosophy, history and sociology of science and for some issues in general epistemology.
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