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Search Results: 1 - 10 of 481449 matches for " Marco A; Mu?oz "
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Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Ni?o
MUOZ,PRAXEDES; SALAMANCA,MARCO A; NEIRA,CARLOS; SELLANES,JAVIER;
Revista chilena de historia natural , 2004, DOI: 10.4067/S0716-078X2004000200009
Abstract: two stations representing coastal and shelf environments (bay of concepción and adjacent shelf, respectively) were sampled in order to assess benthic nitrogen fluxes. during the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 el ni?o event. from both sites, intact sediment cores were collected for incubation experiments to directly estimate total ammonium fluxes. pore-water chemistry was also assessed to estimate diffusive fluxes of nitrogen compounds (nh4+, no3- and no2-). the nh4+ flux from incubation experiments ranged from 0.55 to 2.18 mmol m-2 day-1 in the inner bay and from 1.84 to 2.14 mmol m-2 day-1 on the shelf. no3- diffusive fluxes to the sediments were observed in the bay in march (-17 x 10-2 mmol m-2 day-1) and on the shelf in november (-2.7 x 10-2 mmol m-2 day-1), associated with the lowest nh4+ diffusive fluxes and coincident with a stronger gradient of eh in the first centimeters of the sediments. besides, total nh4+ fluxes lower than in normal periods were observed, suggesting the influence of less reducing conditions, consequence in turn of the lower fluxes of particulated organic material and higher dissolved oxygen in the bottom waters. these conditions were probably imposed by the el ni?o event. on the other hand, and relative to previous reports, an increase of irrigation coefficients (di) was estimated. thus, the flux extension of other nitrogen compounds could have acquired relevance in relation to nh4+ fluxes during the study period
Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Ni o Flujos de compuestos nitrogenados desde los sedimentos, en un sistema de surgencia de Chile central (Bahía Concepción y plataforma adyacente) durante El Ni o 1997-1998
PRAXEDES MUOZ,MARCO A SALAMANCA,CARLOS NEIRA,JAVIER SELLANES
Revista chilena de historia natural , 2004,
Abstract: Two stations representing coastal and shelf environments (bay of Concepción and adjacent shelf, respectively) were sampled in order to assess benthic nitrogen fluxes. During the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 El Ni o event. From both sites, intact sediment cores were collected for incubation experiments to directly estimate total ammonium fluxes. Pore-water chemistry was also assessed to estimate diffusive fluxes of nitrogen compounds (NH4+, NO3- and NO2-). The NH4+ flux from incubation experiments ranged from 0.55 to 2.18 mmol m-2 day-1 in the inner bay and from 1.84 to 2.14 mmol m-2 day-1 on the shelf. NO3- diffusive fluxes to the sediments were observed in the bay in March (-17 x 10-2 mmol m-2 day-1)and on the shelf in November (-2.7 x 10-2 mmol m-2 day-1), associated with the lowest NH4+ diffusive fluxes and coincident with a stronger gradient of Eh in the first centimeters of the sediments. Besides, total NH4+ fluxes lower than in normal periods were observed, suggesting the influence of less reducing conditions, consequence in turn of the lower fluxes of particulated organic material and higher dissolved oxygen in the bottom waters. These conditions were probably imposed by the El Ni o event. On the other hand, and relative to previous reports, an increase of irrigation coefficients (DI) was estimated. Thus, the flux extension of other nitrogen compounds could have acquired relevance in relation to NH4+ fluxes during the study period Se analizaron los flujos de compuestos nitrogenados desde los sedimentos en dos áreas representativas de condiciones costeras y de plataforma (Bahía Concepción y plataforma adyacente, respectivamente). Durante el período de muestreo las aguas de fondo presentaron un anómalamente alto contenido de oxígeno disuelto, coincidente con el evento El Ni o 1997-1998. De ambos sitios, se incubaron testigos de sedimento intactos para determinar los flujos totales de NH4+. Además se determinó la concentración de NH4+, NO3- y NO2- en el agua intersticial para estimar los flujos difusivos de compuestos nitrogenados en la interfase agua-sedimento. Los flujos de NH4+ totales variaron entre 0,55 y 2,18 mmol m-2 día-1 al interior de la bahía y entre 1,84 a 2,14 mmol m-2 día-1 en la plataforma. Se observaron flujos difusivos de NO3- en dirección a los sedimentos al interior de la bahía en Marzo de 1998 (-17 x 10-2 mmol m-2 día-1)y en la plataforma en Noviembre de 1997 (-2,7 x 10-2 mmol m-2 día-1) asociados a los flujos difusivos de NH4+ más bajos, coincidiendo e
Corresponde la Agrupación de Fondos de Inversión en Chile con su Clasificación Pública?: Un Análisis de los Factores Determinantes
Luis Ferruz A.,Isabel Marco S.,Fernando Muoz S.
Panorama Socioeconómico , 2007,
Abstract: En este trabajo se analiza si existe algún patrón de comportamiento en el mercado de fondos de inversión chileno que permita clasificarlos, y si la clasificación obtenida coincide o no con la clasificación pública de la que son objeto a partir de la información suministrada por las entidades gestoras. Para ello se llevó a cabo un análisis de la rentabilidad mensual obtenida por cada fondo durante el período comprendido entre agosto de 2004 y marzo de 2007, aplicando las técnicas de análisis cluster y análisis factorial. Los resultados que se obtuvieron del análisis factorial permiten concluir que en la configuración del mercado de fondos de inversión chileno influyen cinco factores: propensión a invertir en renta variable, propensión a invertir en renta fija, aversión al riesgo de tipo de interés, propensión a invertir en horizontes temporales a mediano y largo plazo, y aversión al riesgo de mercado, aunque este último factor no puede ser interpretado claramente. El análisis cluster conduce a pensar que, salvo algunas excepciones, la clasificación pública de los fondos de inversión en Chile se corresponde con la agrupación que presentan en el mercado.
La fiesta patronal de Xico, Veracruz.Tradición oral y festividad
María Madrazo Miranda,Marco Urdapilleta Muoz
Ciencia Ergo Sum , 2008,
Abstract: Se describen algunos aspectos dela fiesta patronal en Santa María Magdalena enXico, Veracruz, particularmente los elementosculturales indígenas incorporados a la culturafestiva xique a bajo los términos de tradiciónoral . Además de constatar su presencia deestos elementos culturales, se observa que sevan ocultando cada vez más, incluso puedepensarse que su transformación apunta envarios casos hacia su pérdida u olvido. Eltrabajo estuvo enfocado de manera particularal arco floral y al mito-narración de Juan delMonte y a las vivencias de identidad quegenera los relatos sobre la imagen de SantaMaría Magdalena.
Climate Based Risk Assessment for Maize Producing Areas in Rainfed Agriculture in Mexico  [PDF]
I. Sanchez Cohen, G. Esquivel Arriaga, M. A. Velasquez Valle, Marco A. Inzunza Ibarra, Arcadio Muoz Villalobos, P. Bueno Hurtado
Journal of Water Resource and Protection (JWARP) , 2014, DOI: 10.4236/jwarp.2014.613112
Abstract: Rainfed areas in Mexico accounts for 14 million hectares where around 23 million people live and are located in places where there is a little climatic information. The severe drought that has impacted northern Mexico in the past several years as well as other parts of the country, has forced decision takers to look for improved tools and procedures to prevent and to cope with this natural hazard. For this paper, the methodology of the Food and Agricultural Organization of the United Nations (FAO) for estimating water balance variables was modified to provide crop yield estimations under rainfed agriculture in maize producer states of Mexico. The water balance accounts for the daily variation of soil water content having main input rainfall (Pp) and main output crop evapotranspiration (Eta). The algorithm computes crop yield using two distinctive approaches: 1) one based on surplus/deficit functions for each crop considered and 2) yield estimations based on soil water balance and water function productions of the crop being analyzed. For computing water balance and crop yields, a computer model is built that incorporates the FAO method for water balance (MODEL SICTOD: Computational System for Decision Taking, acronym in Spanish) which stochastically generate precipitation based on wet/dry transition probabilities using a first order Markov chain scheme. Maps of average crop yields were obtained after interpolating model outcomes for the main maize producer states of Mexico: Jalisco, Michoacan, Guerrero, Puebla Oaxaca and Chiapas. Different planting dates were analyzed, early (90 days of length period), intermediate (120 days of length period) and late (150 days of length period). Crop yield variability correlates to the transition probability on having a wet day following a dry day. Results have shown high yield variation and probability of crop yield failure and climatic risk follows a distinctive pattern according to planting date and rainfall occurrence. The approach used is of great support for decision taking processes.
The cellular mechanisms of body iron homeostasis
NU?EZ,MARCO T; GARATE,MARCO A; ARREDONDO,MIGUEL; TAPlA,VICTORIA; MUOZ,PATRICIA;
Biological Research , 2000, DOI: 10.4067/S0716-97602000000200013
Abstract: cells tightly regulate iron levels through the activity of iron regulatory proteins (irps) that bind to rna motifs called iron responsive elements (ires). when cells become iron-depleted, irps bind to ires present in the mrnas of ferritin and the transferrin receptor, resulting in diminished translation of the ferritin mrna and increased translation of the transferrin receptor mrna. similarly, body iron homeostasis is maintained through the control of intestinal iron absorption. intestinal epithelia cells sense body iron through the basolateral endocytosis of plasma transferrin. transterrin endocytosis results in enterocytes whose iron content will depend on the iron saturation of plasma transferrin. cell iron levels, in turn, inversely correlate with intestinal iron absorption. in this study, we examined the relationship between the regulation of intestinal iron absorption and the regulation of intracellular iron levels by caco-2 cells. we asserted that irp activity closely correlates with apical iron uptake and transepithelial iron transport. moreover, overexpression of ire resulted in a very low labile or reactive iron pool and increased apical to basolateral iron flux. these results show that iron absorption is primarily regulated by the size of the labile iron pool, which in turn is regulated by the ire/irp system.
Growth and mortality of the fish Citharichthys xanthostigma (Pleuronectiformes: Paralichthyidae) off the Western coast of Baja California, México
Martínez-Muoz,Marco A; Ortega-Salas,Armando A;
Revista de Biología Tropical , 2010,
Abstract: longfin sanddab (citharichthys xanthostigma) represents a very important fishery resource in southern and baja california but are not very well known. the purpose of this study is to provide information on the growth and mortality of longfin sanddab population in the mexican pacific ocean at baja california, méxico. data on growth were obtained for longfin sanddab collected with otter trawls during six cruises off the western coast of baja california. a total of 1 017 longfin sanddab were caught over the sampling period, and from 860 specimens, the male to female ratio was 1:1.8. the relationship between total weight (w) and standard length (sl) is described: w=0.00000743 sl3.196 for females and w=0.00000764 sl3.193 for males. age groups were estimated from length frequency data, and von bertalanffy annual growth parameters for all fish data combined were the following: l∞=289.2mm sl, k=0.20, t0=-0.73; for males, they were l∞=265.9mm sl, k=0.21, t0=-0.68, and for females, l∞=293.6mm sl, k=0.23, t0=-0.35. longfin sanddab caught during this study reached a maximum age of 10 years, and at that age, males attained smaller sizes than females. the age groups had a total mortality (z) rate of 0.82 year-1, a fishing mortality (f) of 0.52 year-1, and a natural mortality (m) of 0.3 year-1. although the longfin sanddab is not a target species of commercial fisheries, it suffers high mortality as part of the bycatch in the shrimp fishery. rev. biol. trop. 58 (2): 689-705. epub 2010 june 02.
Growth and mortality of the fish Citharichthys xanthostigma (Pleuronectiformes: Paralichthyidae) off the Western coast of Baja California, México
Marco A Martínez-Muoz,Armando A Ortega-Salas
Revista de Biología Tropical , 2010,
Abstract: Longfin sanddab (Citharichthys xanthostigma) represents a very important fishery resource in Southern and Baja California but are not very well known. The purpose of this study is to provide information on the growth and mortality of longfin sanddab population in the Mexican Pacific Ocean at Baja California, México. Data on growth were obtained for longfin sanddab collected with otter trawls during six cruises off the Western coast of Baja California. A total of 1 017 longfin sanddab were caught over the sampling period, and from 860 specimens, the male to female ratio was 1:1.8. The relationship between total weight (W) and standard length (SL) is described: W=0.00000743 SL3.196 for females and W=0.00000764 SL3.193 for males. Age groups were estimated from length frequency data, and von Bertalanffy annual growth parameters for all fish data combined were the following: L∞=289.2mm SL, k=0.20, t0=-0.73; for males, they were L∞=265.9mm SL, k=0.21, t0=-0.68, and for females, L∞=293.6mm SL, k=0.23, t0=-0.35. Longfin sanddab caught during this study reached a maximum age of 10 years, and at that age, males attained smaller sizes than females. The age groups had a total mortality (Z) rate of 0.82 year-1, a fishing mortality (F) of 0.52 year-1, and a natural mortality (M) of 0.3 year-1. Although the longfin sanddab is not a target species of commercial fisheries, it suffers high mortality as part of the bycatch in the shrimp fishery. Rev. Biol. Trop. 58 (2): 689-705. Epub 2010 June 02. Se presenta información sobre el crecimiento y mortalidad de la población del C. xanthostigma (lenguado alón) en el Pacífico Mexicano de Baja California, México. Datos sobre su crecimiento fueron obtenidos de peces capturados con red de arrastre durante seis cruceros en la costa Oeste de Baja California, México. Se capturaron 1 017 peces en este periodo. La relación machos:hembras de 860 ejemplares fue de 1:1.2. La relación peso total (W) y longitud estándar (SL) se estimó para hembras: W=0.00000743 SL 3.196 y para machos: W=0.00000764 SL 3.193. La edad de los grupos se calculó con datos de frecuencia por longitud, el crecimiento de von Bertalanffy global fue: L∞=289.2mm SL, k=0.20, t0= -0.73; para los machos: L∞=265.9 mm SL, k=0.21, t0= -0.68 y para las hembras: L∞=293.6mm SL, k=0.23, t0=-0.35, anualmente. La captura de C. xanthostigma durante este estudio alcanzó una edad máxima de 10 a os. Los machos alcanzan tallas menores que las hembras a la misma edad. Los grupos de edad tuvieron una tasa de mortalidad total (Z) de 0.82 por a o, una mortalidad por pesca (F) de 0.52 por a
Identification of a minimal microsatellite marker panel for the fingerprinting of peach and nectarine cultivars
Rojas,Gabriela; Méndez,Marco A; Muoz,Carlos; Lemus,Gamalier; Hinrichsen,Patricio;
Electronic Journal of Biotechnology , 2008,
Abstract: the genetic characterization of 117 peach and nectarine cultivars (prunus persica (l.) batsch) using microsatellite (ssr) markers is presented. analyzed genotypes include the complete list of cultivars under intellectual property (ip) protection in chile. one hundred and two out of the 117 cultivars under study could be identified using only 7 ssrs. other 5 cultivars were differentiated using 3 additional markers, but 5 pairs of genotypes were not differentiable. the average expected heterozygosity for the set of markers was 0.55, ranging from 0.28 in bppct-008 to 0.81 in cppct-022, with an f value of 0.37. a neighbor-joining dendrogram showed that, with few exceptions, peaches and nectarines clustered separately. these results are the basis for the development of a fingerprinting protocol for the unequivocal identification of most of the peach and nectarine cultivars officially registered in chile.
"PASADO A LLEVAR": LA VIOLENCIA EN LA EDUCACIóN MEDIA MUNICIPALIZADA
Villalta Páucar,Marco Antonio; Saavedra,Eugenio; Muoz,María Teresa;
Estudios pedagógicos (Valdivia) , 2007, DOI: 10.4067/S0718-07052007000100003
Abstract: an inquiry is being made regarding the subjective components which make up the social dynamics of violence lived by adolescent students of 13 and 14 years of age, pupils of first year at a secondary school of the 7o region in chile. techniques of qualitatives investigation are used in the compilation and the analysis of the information, complemented with the use of a questionnaire to a 243 students of the establishmet. among the findings it is sustained that the violence dynamics among peers, supposes two dominant rules which form part of the subculture of the school?s adolescents: 1) violence is normal; 2) living together with one?s peers means a permanent relationship among equals. generally the ?symmetrical ideal? is a relevant fact to configurate the violence dynamics
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