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Search Results: 1 - 10 of 352267 matches for " Juan S. Monrós "
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Breeding success of a colony of Boat-billed Herons Cochlearius cochlearius (Ciconiiformes: Ardeidae) in pasturelands of Costa Rica
Gómez,Jaime; Gil-Delgado,José A; Monrós,Juan S;
Revista de Biología Tropical , 2006,
Abstract: the breeding success of a double-brooding colony of boat-billed herons cochlearius cochlearius was studied in pasturelands of costa rica. mean clutch size in the first clutches (2.9 eggs/nest) was higher than in second and repeat clutches (2.3 eggs/nest). breeding success was similar in the first attempt and second attempts(20.7 % and 21.7 %, respectively). in both attempts earlier nests enjoyed a higher breeding success. starvation of the youngest chicks within the nest and destruction of nests by bad weather conditions were the main factors related to nestling death. no effects of human activity on the reproduction of the breeding colony were observed. rev. biol. trop. 54 (4): 1131-1134. epub 2006 dec. 15
Breeding success of a colony of Boat-billed Herons Cochlearius cochlearius (Ciconiiformes: Ardeidae) in pasturelands of Costa Rica
Jaime Gómez,José A Gil-Delgado,Juan S Monrós
Revista de Biología Tropical , 2006,
Abstract: The breeding success of a double-brooding colony of Boat-billed Herons Cochlearius cochlearius was studied in pasturelands of Costa Rica. Mean clutch size in the first clutches (2.9 eggs/nest) was higher than in second and repeat clutches (2.3 eggs/nest). Breeding success was similar in the first attempt and second attempts(20.7 % and 21.7 %, respectively). In both attempts earlier nests enjoyed a higher breeding success. Starvation of the youngest chicks within the nest and destruction of nests by bad weather conditions were the main factors related to nestling death. No effects of human activity on the reproduction of the breeding colony were observed. Rev. Biol. Trop. 54 (4): 1131-1134. Epub 2006 Dec. 15 Estudiamos el éxito reproductivo de una colonia del ave Cochlearius cochlearius en una zona ganadera de Costa Rica. El promedio de huevos por nido fue mayor durante el periodo de primeras puestas (2.9 huevos/nido) que durante el periodo de segundas puestas y reposiciones (2.3 huevos/nido). El éxito reproductor de los dos periodos fue similar (20.7 % y 21.7 %, respectivamente). En ambos tuvieron más éxito las parejas que comenzaron la puesta antes. Las principales causas de mortandad fueron inanición de los pollos más jóvenes del nido y la destrucción de los nidos debido a condiciones climáticas adversas. No notamos efectos adversos por la actividad humana
Phenotypic Divergence among West European Populations of Reed Bunting Emberiza schoeniclus: The Effects of Migratory and Foraging Behaviours
Júlio M. Neto, Luís Gordinho, Eduardo J. Belda, Marcial Marín, Juan S. Monrós, Peter Fearon, Ross Crates
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063248
Abstract: Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection.
Phylogeography of a Habitat Specialist with High Dispersal Capability: The Savi’s Warbler Locustella luscinioides
Júlio M. Neto, José L. Arroyo, Bruno Bargain, Juan S. Monrós, Norbert Mátrai, Petr Procházka, Pavel Zehtindjiev
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038497
Abstract: In order to describe the influence of Pleistocene glaciations on the genetic structure and demography of a highly mobile, but specialized, passerine, the Savi’s Warbler (Locustella luscinioides), mitochondrial DNA sequences (ND2) and microsatellites were analysed in c.330 individuals of 17 breeding and two wintering populations. Phylogenetic, population genetics and coalescent methods were used to describe the genetic structure, determine the timing of the major splits and model the demography of populations. Savi’s Warblers split from its sister species c.8 million years ago and have two major haplotype groups that diverged in the early/middle Pleistocene. One of these clades originated in the Balkans and is currently widespread, showing strong evidence for population expansion; whereas the other is restricted to Iberia and remained stable. Microsatellites agreed with a genetic break around the Pyrenees, but showed considerable introgression and a weaker genetic structure. Both genetic markers showed an isolation-by-distance pattern associated with the population expansion of the eastern clade. Breeding populations seem to be segregated at the wintering sites, but results on migratory connectivity are preliminary. Savi’s Warbler is the only known migratory bird species in which Iberian birds did not expand beyond the Pyrenees after the last glaciation. Despite the long period of independent evolution of western and eastern populations, complete introgression occurred when these groups met in Iberia. Mitochondrial sequences indicated the existence of refugia-within-refugia in the Iberian Peninsula during the last glacial period, which is surprising given the high dispersal capacity of this species. Plumage differences of eastern subspecies seemed to have evolved recently through natural selection, in agreement with the glacial expansion hypothesis. This study supports the great importance of the Iberian Peninsula and its role for the conservation of genetic variation.
Quantum learning of classical stochastic processes: The Completely-Positive Realization Problem
Alex Monràs,Andreas Winter
Mathematics , 2014,
Abstract: Among several tasks in Machine Learning, a specially important one is that of inferring the latent variables of a system and their causal relations with the observed behavior. Learning a Hidden Markov Model of given stochastic process is a textbook example, known as the positive realization problem (PRP). The PRP and its solutions have far-reaching consequences in many areas of systems and control theory, and positive systems theory. We consider the scenario where the latent variables are quantum states, and the system dynamics is constrained only by physical transformations on the quantum system. The observable dynamics is then described by a quantum instrument, and the task is to determine which quantum instrument --if any-- yields the process at hand by iterative application. We take as starting point the theory of quasi-realizations, whence a description of the dynamics of the process is given in terms of linear maps on state vectors and probabilities are given by linear functionals on the state vectors. This description, despite its remarkable resemblance with the Hidden Markov Model, or the iterated quantum instrument, is nevertheless devoid of any stochastic or quantum mechanical interpretation, as said maps fail to satisfy any positivity conditions. The Completely-Positive realization problem then consists in determining whether an equivalent quantum mechanical description of the same process exists. We generalize some key results of stochastic realization theory, and show that the problem has deep connections with operator systems theory, yielding possible insight to the lifting problem in quotient operator systems. Our results have potential applications in quantum machine learning, device-independent characterization and reverse-engineering of stochastic processes and quantum processors, and dynamical processes with quantum memory.
Tratamiento de la disfunción eréctil tras prostatectomía radical con sildenafilo en un grupo no seleccionado de pacientes
Rubio Briones,J.; Iborra Juan,I.; Dumont Martínez,R.; Casanova Ramón-Borja,J.; Monrós Lliso,J.L.; Ricós Torrent,J.V.; Collado Serra,A.; Solsona Narbón,E.;
Actas Urológicas Espa?olas , 2004, DOI: 10.4321/S0210-48062004000800002
Abstract: objective: to evaluate erectile disfunction (ed) after radical prostatectomy in a non selected group of patients and their response to sildenafil. methods: we included our patients who were operated on between 1998 and 2001. the patients filled in a modification of iief (miief) before the rp operation. we tried sildenafil with doses of 100 mg in 3 different periods: 3-6, 12 and 18-24 months after the rp operation. in the event of a complete response they filled in the miief again. results: the mean age of the patients was 62.8 years old and the mean observation period was 31.7 months. only 111 (62%) of the total number of patients operated on wanted treatment and only 90 took sildenafil in the proposed protocol; 27 (30%), 18 (20%) and 45 (50%) patients had a complete response, a partial response or no response to the sildenafil respectively. the miief showed 6.5±5.7 points less than the miief pre-treatment. in the univariate analysis, the preservation of bundles, the presence of a previous partial response and the presence of the previous tumescence were significantly related to the complete response; however, only tumescence kept its value in the multivariate study. conclusions: urologists must involve themselves in the early rehabilitation of the erectile function even in those patients where preservation of the nvb was not possible. one must always try to preserve, uni or bilaterally, whenever the patient desires preservation of ef. the response to sildenafil is better after the first year and in patients who have previous tumescence.
Caracterización cerámica de los sedimentos de la Albufera de Valencia
Vicente, M.,Llusar, M.,Monrós, G.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2003,
Abstract: The Albufera is recognised as Natural Park by Generalitat Valenciana decree of 8′th July 1989 and is listed on the wet areas of international importance of the Ramsar Conference since 8′th May 1990. Batimetry studies show the gradual full up of the lake. If the stuffing and pollution process persist, lamentably, in order to preserve the lake identity it will be necessary to extract the sediments which must be environmental adequately managed. In this study the ceramic characteristics of the Albufera of Valencia sediments have been analysed in order to know the possibility of their use as ceramic raw material or as additive to ceramic stoneware of the valencian tile industry. El lago de la Albufera es Parque Natural por decreto de 8 de Julio de 1989 de la Generalitat Valenciana y está desde el 8 de Mayo de 1990 en el listado de Zonas Húmedas de importancia internacional de la Conferencia de Ramsar. Los estudios de batimetría del lago indican que el lago continúa su proceso lento de colmatación, Si el proceso de colmatación y contaminación persevera o se inducen severas contaminaciones locales por vertidos, es posible que lamentablemente, para preservar la identidad del sistema, sea necesario dragar el lago de forma selectiva y cuidadosa siendo necesario dar un fin último a los fangos obtenidos. En este estudio se analizan las características de los sedimentos de la Albufera de Valencia desde el punto de vista cerámico, con el fin de Conocer las posibles utilizaciones de los mismos para la producción de algún tipo de cerámica o como componentes de adición a pastas cerámicas de la industria azulejera Valenciana.
Biomimetic, Mild Chemical Synthesis of CdTe-GSH Quantum Dots with Improved Biocompatibility
José M. Pérez-Donoso, Juan P. Monrás, Denisse Bravo, Adam Aguirre, Andrew F. Quest, Igor O. Osorio-Román, Ricardo F. Aroca, Thomas G. Chasteen, Claudio C. Vásquez
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030741
Abstract: Multiple applications of nanotechnology, especially those involving highly fluorescent nanoparticles (NPs) or quantum dots (QDs) have stimulated the research to develop simple, rapid and environmentally friendly protocols for synthesizing NPs exhibiting novel properties and increased biocompatibility. In this study, a simple protocol for the chemical synthesis of glutathione (GSH)-capped CdTe QDs (CdTe-GSH) resembling conditions found in biological systems is described. Using only CdCl2, K2TeO3 and GSH, highly fluorescent QDs were obtained under pH, temperature, buffer and oxygen conditions that allow microorganisms growth. These CdTe-GSH NPs displayed similar size, chemical composition, absorbance and fluorescence spectra and quantum yields as QDs synthesized using more complicated and expensive methods. CdTe QDs were not freely incorporated into eukaryotic cells thus favoring their biocompatibility and potential applications in biomedicine. In addition, NPs entry was facilitated by lipofectamine, resulting in intracellular fluorescence and a slight increase in cell death by necrosis. Toxicity of the as prepared CdTe QDs was lower than that observed with QDs produced by other chemical methods, probably as consequence of decreased levels of Cd+2 and higher amounts of GSH. We present here the simplest, fast and economical method for CdTe QDs synthesis described to date. Also, this biomimetic protocol favors NPs biocompatibility and helps to establish the basis for the development of new, “greener” methods to synthesize cadmium-containing QDs.
Enhanced Glutathione Content Allows the In Vivo Synthesis of Fluorescent CdTe Nanoparticles by Escherichia coli
Juan P. Monrás, Víctor Díaz, Denisse Bravo, Rebecca A. Montes, Thomas G. Chasteen, Igor O. Osorio-Román, Claudio C. Vásquez, José M. Pérez-Donoso
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048657
Abstract: The vast application of fluorescent semiconductor nanoparticles (NPs) or quantum dots (QDs) has prompted the development of new, cheap and safer methods that allow generating QDs with improved biocompatibility. In this context, green or biological QDs production represents a still unexplored area. This work reports the intracellular CdTe QDs biosynthesis in bacteria. Escherichia coli overexpressing the gshA gene, involved in glutathione (GSH) biosynthesis, was used to produce CdTe QDs. Cells exhibited higher reduced thiols, GSH and Cd/Te contents that allow generating fluorescent intracellular NP-like structures when exposed to CdCl2 and K2TeO3. Fluorescence microscopy revealed that QDs-producing cells accumulate defined structures of various colors, suggesting the production of differently-sized NPs. Purified fluorescent NPs exhibited structural and spectroscopic properties characteristic of CdTe QDs, as size and absorption/emission spectra. Elemental analysis confirmed that biosynthesized QDs were formed by Cd and Te with Cd/Te ratios expected for CdTe QDs. Finally, fluorescent properties of QDs-producing cells, such as color and intensity, were improved by temperature control and the use of reducing buffers.
Doping and synthesis method effect on zirconium silicate conductivity
Monrós, G.,Badenes, J.,Meseguer, S.,Llusar, M.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2006,
Abstract: The colour mechanisms of blue V- ZrSiO4 and yellow Pr- ZrSiO4 ceramic pigments which strongly depend on both fluorine addition and synthesis method, are still controversial. Complex impedance has been used as a useful tool to differentiate the materials as a function of the synthesis method, microstructure and observed colour, going deeply into the resolution of controversies about the nature of colours. Representative samples of these doping pigmenting systems prepared by both classical ceramic process and sol-gel method have been studied by complex impedance analysis. Vanadium doped zircon enhances resistivity and activation energy compared to undoped zircon powder and turkish blue vanadium-zircon obtained by addition of NaF shows the highest bulk resistivity. Activation energy and conductivity decrease for Praseodymium doped zircon compared to undoped zircon. This feature is in agreement with the presence of cationic vacancies on green vanadiumzircon samples due to V4+ and V5+ coexistence and praseodymium oxide inclusions on Pr- ZrSiO4 yellow pigment. El mecanismo del color en el azul de los pigmentos cerámicos V- ZrSiO4 y amarillo de Pr- ZrSiO4 cuyos tinos dependen mucho de la presencia de fluoruros así como del método de preparación esta controvertido en la literatura. La impedancia compleja se ha utilizado como una herramienta útil para diferenciar los materiales en función del método de síntesis, la microestructura y el color con el fin de profundizar en la resolución de las controversias. Se han preparado muestras representativas de ambos sistemas dopados mediante diferentes métodos de síntesis cerámico y sol-gel que se han estudiado por análisis de impedancia compleja. El circón dopado con vanadio aumenta su resistividad y sus energía de activación con referencia a la muestra no dopada y la muestra turquesa obtenida por adición de NaF presenta la mayor resistividad. Las muestras dopadas con praseodimio disminuyen la energía de activación y la conductividad respecto de la muestra no dopada. Este comportamiento está de acuerdo con la presencia de vacantes catiónicas en las muestras verdes de vanadiocircón asociadas a la coexistencia de V4+ y V5+ en las muestras y de inclusiones de óxido de praseodimio en el pigmento amarillo de Pr- ZrSiO4.
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