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Search Results: 1 - 10 of 6465 matches for " Gerardo; Soto "
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Comment on Synthesis of rhenium nitride crystal with MoS2 structure
Gerardo Soto
Physics , 2012,
Abstract: Kawamura et. al. recently published an article about the synthesis of rhenium nitride with MoS2-type structure [APL 100, 251910(2012)]. We disagree with the composition proposed by Kawamura. The compound synthesized by Kawamura is ReN3, or a compound of similar composition. What Kawamura did is to find the Re atomic positions of a compound where the nitrogen concentration remains unknown. This paper was rejected form APL. The reviewer comments (and our reply) are included here.
Regulación por precios tope
Gerardo Soto Carrillo
Revista Economía , 2009,
Abstract: El presente trabajo describe las principales características del mecanismo de regulación por precios tope, incluyendo su ubicación dentro de las posibilidades de acción regulatoria, las críticas que se han planteado al mismo, así como los mecanismos complementarios utilizados y los riesgos involucrados en su desarrollo. --- This article describes the main characteristics of the price cap regime of price regulation, including its location among other regulatory possibilities, critics received, complementary mechanisms and risks involved in its development.
Country annual report from Costa Rica (2011) to the International Commission on the History of Geological Sciences (INHIGEO) Informe anual de Costa Rica (2011) a la Comisión Internacional sobre Historia de las Ciencias Geológicas (INHIGEO)
Gerardo J. Soto
Revista Geológica de América Central , 2012,
Abstract:
Country annual report to INHIGEO, Costa Rica 2010 Informe anual de INHIGEO, Costa Rica 2010
Gerardo J Soto
Revista Geológica de América Central , 2011,
Abstract:
FABRICACION DE PELLETS DE CARBONILLA, USANDO ASERRIN DE Pinus radiata (D. Don), COMO MATERIAL AGLOMERANTE
Soto,Gerardo; Nú?ez,Miguel;
Maderas. Ciencia y tecnología , 2008, DOI: 10.4067/S0718-221X2008000200005
Abstract: in the present study, it was used charcoal of vegetal coal and sawdust of pinus radiata (d. don) to manufacture pellets, these had similars characteristics by weight, volume and density, keeping as the only variable, the sawdust and charcoal quantity of each pellet. using a manual screw press, was manufactured a total of 1180 pellets with 15 different charcoal and sawdust proportions. with these pellets were conducted a friability and calorific power essays. this latter property was determined using a protocol for measuring and german standard din 51900. according to the results, was concluded that is possible manufacture pellets of charcoal, using sawdust of pinus radiata (d. don) as a adhesive material, with 50% of both raw materials, obtaining the optimum combination with a 47.5% of charcoal and a friability of 0.935, achieving a gain energy of 24.25% compared to a 100% pellets of sawdust.
A NEW SPECIES OF DEIREGYNE (ORCHIDACEAE, SPIRANTHINAE) FROM MEXICO
Miguel á Soto,Gerardo A. Salazar
Acta botánica mexicana , 2012,
Abstract: Se describe e ilustra Deiregyne tenorioi Soto Arenas & Salazar, especie nueva de los estados de Hidalgo, Estado de México, Oaxaca, Puebla y Tlaxcala en México. Es similar a D. eriophora (B.L. Rob. & Greenm.) Garay y a D. chartacea (L.O. Williams) Garay; de la primera se distingue por el ovario y la inflorescencia con el raquis esparcidamente glandular-pubescente (vs. lanuginoso), las flores inodoras y el labelo proporcionalmente más largo y angosto, con garganta de color verde brillante a amarillo limón, angosta, con los lados rectos (vs. garganta amarilla dorada, amplia, con los lados redondeados); de la segunda difiere en las flores mucho más grandes, los sépalos y pétalos no te idos de color café verdoso abajo de la mitad, los sépalos laterales extendidos (vs. fuertemente recurvados) y el lóbulo distal del labelo proporcionalmente más largo y angosto.
FABRICACION DE PELLETS DE CARBONILLA, USANDO ASERRIN DE Pinus radiata (D. Don), COMO MATERIAL AGLOMERANTE MANUFACTURING PELLETS OF CHARCOAL, USING SAWDUST OF Pinus radiata (D. Don), AS A BINDER MATERIAL
Gerardo Soto,Miguel Nú?ez
MADERAS : Ciencia y Tecnología , 2008,
Abstract: En el presente estudio, se utilizó carbonilla de carbón vegetal y aserrín de Pinus radiata (D. Don) para fabricar pellets, con similares características en peso, volumen y densidad, manteniendo como única variable, la cantidad de aserrín y carbonilla en cada pellets. Utilizando una prensa de tornillo manual, se elaboró un total de 1180 pellets con 15 proporciones distintas de carbonilla y aserrín. Con estos pellets se realizaron ensayos de friabilidad y poder calorífico. Esta última propiedad se determinó utilizando un protocolo de medición y la Norma alemana DIN 51900. Según los resultados, se concluye que es posible fabricar pellets de carbonilla, utilizando aserrín de Pinus radiata (D. Don) como material aglomerante, con un 50 % de ambas materias primas, obteniendo la combinación óptima con un 47,5% de carbonilla y una friabilidad de 0,935, logrando una ganancia energética de 24,25% con respecto a un pellet de 100 % de aserrín. In the present study, it was used charcoal of vegetal coal and sawdust of Pinus radiata (D. Don) to manufacture pellets, these had similars characteristics by weight, volume and density, keeping as the only variable, the sawdust and charcoal quantity of each pellet. Using a manual screw press, was manufactured a total of 1180 pellets with 15 different charcoal and sawdust proportions. With these pellets were conducted a friability and calorific power essays. This latter property was determined using a protocol for measuring and German Standard DIN 51900. According to the results, was concluded that is possible manufacture pellets of charcoal, using sawdust of Pinus radiata (D. Don) as a adhesive material, with 50% of both raw materials, obtaining the optimum combination with a 47.5% of Charcoal and a friability of 0.935, achieving a gain energy of 24.25% compared to a 100% pellets of sawdust.
Effect of artificial feeders on pollen loads of the hummingbirds of Cerro de La Muerte, Costa Rica
Gerardo Avalos,Alejandra Soto,Willy Alfaro
Revista de Biología Tropical , 2012,
Abstract: Although sugar-water feeders are commonly used by enthusiasts to attract hummingbirds, little is known about how they affect hummingbird behavior and flower use. We studied the highland hummingbird assemblage of Cerro de La Muerte, Costa Rica, both at a site with permanent feeders (La Georgina Restaurant) and further from it. We examined how feeder use and monopolization affected seasonal changes in pollen loads during four sampling periods, including dry and wet seasons, from 2003-2005. We expected that species monopolizing the feeders would carry little or no pollen whatsoever, and would have pollen loads characterized by low floral diversity, in contrast with species less dependent on feeders. We obtained pollen samples from 183 individuals of four hummingbird species captured around the feeders using mist nets, which were compared with a pollen reference collection of plants with a pollination syndrome by hummingbirds. The same methods were implemented at a site 3km away from the feeders. Feeder usage was quantified by counting the number of times hummingbirds drank from the feeders in periods of 4min separated by 1min. The effects of hummingbird species and season on pollen load categories were assessed using a nominal logistic regression. The alpha species at the site, the Fiery-throated Hummingbird (Panterpe insignis), dominated the feeders during the dry season. Meanwhile, in the wet season, feeder usage was more evenly distributed across species, with the exception of the Volcano Hummingbird, Selasphorus flammula, which occupies the last place in the dominance hierarchy. Pollen loads of hummingbirds captured near feeders were low in abundance (more than 50% of captured individuals had zero or low pollen loads), and low in species richness (96% of the hummingbirds with pollen from only one plant genus, Centropogon). Overall pollen loads increased during the dry season coinciding with peaks in flower availability, although the majority of captured hummingbirds carried no pollen. Mist nets located 3km from La Georgina returned few captures (one-to-three specimens) per sampling date, contrasting with observations made before feeders were present. These results suggest that sugar-water feeders gather hummingbirds in over considerable distances drawing them away from flowers. The competitive and antagonistic pattern shown between feeders and flowers indicate that natural pollination system could be significantly altered. Supplementing hummingbirds with food seems likely to interfere with pollination networks already stressed by many anthropogenic effe
Influenza and Pneumonia Mortality in 66 Large Cities in the United States in Years Surrounding the 1918 Pandemic
Rodolfo Acuna-Soto, Cécile Viboud, Gerardo Chowell
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023467
Abstract: The 1918 influenza pandemic was a major epidemiological event of the twentieth century resulting in at least twenty million deaths worldwide; however, despite its historical, epidemiological, and biological relevance, it remains poorly understood. Here we examine the relationship between annual pneumonia and influenza death rates in the pre-pandemic (1910–17) and pandemic (1918–20) periods and the scaling of mortality with latitude, longitude and population size, using data from 66 large cities of the United States. The mean pre-pandemic pneumonia death rates were highly associated with pneumonia death rates during the pandemic period (Spearman ρ = 0.64–0.72; P<0.001). By contrast, there was a weak correlation between pre-pandemic and pandemic influenza mortality rates. Pneumonia mortality rates partially explained influenza mortality rates in 1918 (ρ = 0.34, P = 0.005) but not during any other year. Pneumonia death counts followed a linear relationship with population size in all study years, suggesting that pneumonia death rates were homogeneous across the range of population sizes studied. By contrast, influenza death counts followed a power law relationship with a scaling exponent of ~0.81 (95%CI: 0.71, 0.91) in 1918, suggesting that smaller cities experienced worst outcomes during the pandemic. A linear relationship was observed for all other years. Our study suggests that mortality associated with the 1918–20 influenza pandemic was in part predetermined by pre-pandemic pneumonia death rates in 66 large US cities, perhaps through the impact of the physical and social structure of each city. Smaller cities suffered a disproportionately high per capita influenza mortality burden than larger ones in 1918, while city size did not affect pneumonia mortality rates in the pre-pandemic and pandemic periods.
Proposición de un índice de vigilancia ambiental basado en la variabilidad temporal de la abundancia de dos especies de poliquetos bentónicos de bahía Quintero, Chile
Ca?ete,Juan I; Leighton,Gerardo L; Soto,Eulogio H;
Revista de biología marina y oceanografía , 2000, DOI: 10.4067/S0718-19572000000100007
Abstract: an environmental monitoring index based on the temporal variations in the abundance of two benthic polychaetes (nepthys impressa baird, 1871 and prionospio peruana hartmann-schr?der 1962a) is proposed. three replicated samples were collected in four subtidal stations at quintero bay (32o45' s, 71o29' w; 6 to 13 m deep), central chile, with a van veen grab 0,1 m-2; the sampling campaigns were carried out in march and november 1995 and 1996, april, august and november 1997 and march 1998. this study allowed to evaluate the use of population parameters of the benthic component in environmental impact programs according to the technical requirements of dgtm and mm (chilean navy). nepthys impressa (ni) is a common species whose abundance (n) varied in one order of magnitude and occurred in sediments with low percentage of organic matter, mo (< 1%). instead, prionospio peruana (pp) is an opportunistic species, uncommon, with its abundance varying four orders of magnitude. this species was associated to altered sediments, moderately enriched in terms of organic matter (? 3%). the temporal variations in the abundance of both species allows to propose the environmental monitoring index (iva): iva = log [(nni/(npp + 1))* 100], the index identified three phases at subtidal sediments: a) a moderate enrichment in march, 1996 (3% mo; iva<1) with important population development of p. peruana, b) a recuperation of habitual conditions (< 1% mo; iva ? 3) in seven months retourning to the dominance of n. impressa, and c) after march 1996 iva showed lower values than those obtained before the event of enrichment (iva > 3). the use of this index in other chilean bays is discussed. other eighteen species of benthic polychaetes were collected in the shallow sandy bottom in the study area.
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