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Search Results: 1 - 10 of 240009 matches for " Javier Rodríguez-Pérez "
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Predicting Spatial Patterns of Plant Recruitment Using Animal-Displacement Kernels
Luis Santamaría, Javier Rodríguez-Pérez, Asier R. Larrinaga, Beatriz Pias
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0001008
Abstract: For plants dispersed by frugivores, spatial patterns of recruitment are primarily influenced by the spatial arrangement and characteristics of parent plants, the digestive characteristics, feeding behaviour and movement patterns of animal dispersers, and the structure of the habitat matrix. We used an individual-based, spatially-explicit framework to characterize seed dispersal and seedling fate in an endangered, insular plant-disperser system: the endemic shrub Daphne rodriguezii and its exclusive disperser, the endemic lizard Podarcis lilfordi. Plant recruitment kernels were chiefly determined by the disperser's patterns of space utilization (i.e. the lizard's displacement kernels), the position of the various plant individuals in relation to them, and habitat structure (vegetation cover vs. bare soil). In contrast to our expectations, seed gut-passage rate and its effects on germination, and lizard speed-of-movement, habitat choice and activity rhythm were of minor importance. Predicted plant recruitment kernels were strongly anisotropic and fine-grained, preventing their description using one-dimensional, frequency-distance curves. We found a general trade-off between recruitment probability and dispersal distance; however, optimal recruitment sites were not necessarily associated to sites of maximal adult-plant density. Conservation efforts aimed at enhancing the regeneration of endangered plant-disperser systems may gain in efficacy by manipulating the spatial distribution of dispersers (e.g. through the creation of refuges and feeding sites) to create areas favourable to plant recruitment.
Effects of Frugivore Preferences and Habitat Heterogeneity on Seed Rain: A Multi-Scale Analysis
Javier Rodríguez-Pérez, Asier R. Larrinaga, Luis Santamaría
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033246
Abstract: Seed rain mediated by frugivores is influenced by (1) the seed-deposition distances following fruit ingestion, (2) the disperser activity, as determined by its behaviour and habitat preferences, and (3) the structure of the habitat within the landscape. Here, we evaluated such components using the fleshy-fruited shrub Ephedra fragilis and the frugivorous Balearic lizard Podarcis lilfordi. We estimated seed-deposition patterns based on the displacements and habitat preferences of lizards, derived from visual surveys and telemetry data. The influence of variables potentially determining lizard habitat preference (i.e., height, slope, four measures of habitat abundance and four measures of habitat fragmentation) was evaluated at three spatial scales: ‘home-range’ (c. 2.5–10*103 m2; telemetry data), ‘within home-range’ (c. 100 m2; telemetry data) and ‘microhabitat’ (<100 m2; visual survey). Cumulative lizard displacement (from each telemetric location to the initial capture point) saturated before the peak of seed defecation (seed-retention time), indicating that lizard home-range size and habitat preferences were the main determinants of the spread and shape of seed shadows. Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale. Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales. We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.
Applicability of Solid Solution Heat Treatments to Aluminum Foams
Jaime Lázaro,Eusebio Solórzano,Javier Escudero,Jose Antonio de Saja,Miguel Rodríguez-Pérez
Metals , 2012, DOI: 10.3390/met2040508
Abstract: Present research work evaluates the influence of both density and size on the treatability of Aluminum-based (6000 series) foam-parts subjected to a typical solid solution heat treatment (water quenching). The results are compared with those obtained for the bulk alloy, evaluating the fulfilment of cooling requirements. Density of the foams was modeled by tomography analysis and the thermal properties calculated, based on validated density-scaled models. With this basis, cooling velocity maps during water quenching were predicted by finite element modeling (FEM) in which boundary conditions were obtained by solving the inverse heat conduction problem. Simulations under such conditions have been validated experimentally. Obtained results address incomplete matrix hardening for foam-parts bigger than 70 mm in diameter with a density below 650 kg/m3. An excellent agreement has been found in between the predicted cooling maps and final measured microhardness profiles.
Implicaciones fisiológicas de la osmorregulación en plantas
Rodríguez-Pérez,Loyla;
Agronomía Colombiana , 2006,
Abstract: under natural conditions, the plants are exposed to changing environmental conditions that determine complex respuests that influence in the growth, development and productivity of the crops. the conditions of drought and salinity in the soils are the greater causes of stress in the crops and cause lost economic in the world agriculture. the drought as the salinity are osmotic stress that inhibits the growth and cause interferences at metabolic level. the recognition of the biochemical and physiologic mechanisms involved in the osmoregulation involved in the osmotic stress allows to implement new strategies for the handling and improvement of the cultivations under conditions of stress hidric and saline. different mechanisms are recognized through which the plants manage to adapt and to tolerate the changes in the water potential, between which stand: the water transport by acuaporins, the estomatic closing, the synthesis of compatible osmolites, the ión transport through selective systems of sodium and potassium and those not selective located in the biological membranes and the etrution and compartimentalization of sodium. the osmoregulation confers to the plants the capacity to tolerate conditions of drought and high salinity, with the expression of adaptative mechanisms that avoid the reduction of the photosynthesis, alterations in the allocation photoasimilates and losses in yield, facts that have significant transcendency in the normal physiology of the plant and in the productivity of the crops. the present review has as central objective, to report the discoveries more recent envelope the smorregulation process in exposed cultivated plants to stress by water deficit and by salinity in the soils.
Implicaciones fisiológicas de la osmorregulación en plantas
Rodríguez-Pérez Loyla
Agronomía Colombiana , 2006,
Abstract:
II Seminario Científico Internacional sobre Medicina Veterinaria AGROCIENCIAS2009
Rodríguez-Pérez, Fructuoso
REDVET , 2009,
Abstract: ResumenLa Facultad de Medicina Veterinaria de la Universidad Agraria de laHabana convoca al II Seminario Científico Internacional sobreMedicina Veterinaria, el cual se celebrará en el marco del CongresoInternacional de las Ciencias Agropecuarias “Agrociencias 2009” aefectuarse durante los días 8 al 10 de Julio de 2009, con el objetivo de propiciar un espacio para que especialistas extranjeros y nacionales en diferentes campos de las Ciencias Veterinarias, puedan encontrarse e intercambiar criterios sobre el desarrollo alcanzado en los temas que serán abordados.
Transmission of Beauveria bassiana from male to female Aedes aegypti mosquitoes
Alberto M García-Munguía, Javier A Garza-Hernández, Eduardo A Rebollar-Tellez, Mario A Rodríguez-Pérez, Filiberto Reyes-Villanueva
Parasites & Vectors , 2011, DOI: 10.1186/1756-3305-4-24
Abstract: In an exposure chamber with a filter paper impregnated with 6 × 108 conidia ml -1 of the least and most virulent strains of B. bassiana, 6-8 day old males of A. aegypti were exposed for 48 hours, and then transferred individually (each one was a replicate) to another chamber and confined with twenty healthy females of the same age. Clean males were used in controls. Survival, infection by true mating (insemination) or by mating attempts (no insemination) and fecundity were daily registered until the death of last female. Data analysis was conducted with proc glm for unbalanced experiments and means were separated with the Ryan test with SAS.All strains were highly virulent with LT50 ranging from 2.70 (± 0.29) to 5.33 (± 0.53) days. However the most (Bb-CBG2) and least virulent (Bb-CBG4) isolates were also transmitted by mating behavior; both killed 78-90% of females in 15 days after being confined with males that had previously been exposed for 48 hours to fungi. Of these mortality rates, 23 and 38% respectively, were infections acquired by copulations where insemination occurred. The LT50 for sexually-infected females were 7.92 (± 0.46) and 8.82 (± 0.45) days for both strains, while the one in control was 13.92 (± 0.58). Likewise, fecundity decreased by 95% and 60% for both Bb-CBG2 and Bb-CBG4 isolates in comparison with control. The role of mating attempts in this delivery procedure of B. bassiana is discussed.This is the first report about transmission of B. bassiana by mating behavior from virgin, fungus-contaminated males to females in A. aegypti. Fungal infections acquired by this route (autodissemination) infringed high mortality rates (90%) in mated or approached females. However, prior to releasing virgin, fungus-contaminated males to spread B. basasiana among females of A. aegypti, this novel alternative needs further investigations.Beauveria bassiana is a soil-borne cosmopolitan fungus that infects mostly soil-dwelling insects [1]. For forty two years it
Vectorial Capacity of Aedes aegypti for Dengue Virus Type 2 Is Reduced with Co-infection of Metarhizium anisopliae
Javier A. Garza-Hernández equal contributor,Mario A. Rodríguez-Pérez equal contributor,Ma Isabel Salazar,Tanya L. Russell,Monsuru A. Adeleke,Erik de J. de Luna-Santillana,Filiberto Reyes-Villanueva
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002013
Abstract: Background Aedes aegypti, is the major dengue vector and a worldwide public health threat combated basically by chemical insecticides. In this study, the vectorial competence of Ae. aegypti co-infected with a mildly virulent Metarhizium anisopliae and fed with blood infected with the DENV-2 virus, was examined. Methodology/Principal Findings The study encompassed three bioassays (B). In B1 the median lethal time (LT50) of Ae. aegypti exposed to M. anisopliae was determined in four treatments: co-infected (CI), single-fungus infection (SF), single-virus infection (SV) and control (C). In B2, the mortality and viral infection rate in midgut and in head were registered in fifty females of CI and in SV. In B3, the same treatments as in B1 but with females separated individually were tested to evaluate the effect on fecundity and gonotrophic cycle length. Survival in CI and SF females was 70% shorter than the one of those in SV and control. Overall viral infection rate in CI and SV were 76 and 84% but the mortality at day six post-infection was 78% (54% infected) and 6% respectively. Survivors with virus in head at day seven post-infection were 12 and 64% in both CI and SV mosquitoes. Fecundity and gonotrophic cycle length were reduced in 52 and 40% in CI compared to the ones in control. Conclusion/Significance Fungus-induced mortality for the CI group was 78%. Of the survivors, 12% (6/50) could potentially transmit DENV-2, as opposed to 64% (32/50) of the SV group, meaning a 5-fold reduction in the number of infective mosquitoes. This is the first report on a fungus that reduces the vectorial capacity of Ae. aegypti infected with the DENV-2 virus.
Orbital entanglement production in Andreev billiards with time-reversal symmetry
Sergio Rodríguez-Pérez,Marcel Novaes
Physics , 2013,
Abstract: We study orbital entanglement production in a chaotic cavity connected to four single-channel normal-metal leads and one superconducting lead, assuming the presence of time-reversal symmetry (TRS). The scattered state of two incident electrons is written as the superposition of several two-outgoing quasi-particle states, four of which are orbitally entangled in a left-right bipartition. We calculate numerically the mean value of the squared norm of each scattered state's component, as functions of the number of channels in the superconducting lead. Its behavior is explained as resulting from the proximity effect. We also study statistically the amount of entanglement carried by each pair of outgoing quasi-particles. When the influence of the superconductor is more intense, the average entanglement is found to be considerably larger than that obtained using normal cavities.
Development of a Novel Trap for the Collection of?Black Flies of the Simulium ochraceum?Complex
Mario A. Rodríguez-Pérez, Monsuru A. Adeleke, Nathan D. Burkett-Cadena, Javier A. Garza-Hernández, Filiberto Reyes-Villanueva, Eddie W. Cupp, Laurent Toé, Mario C. Salinas-Carmona, Américo D. Rodríguez-Ramírez, Charles R. Katholi, Thomas R. Unnasch
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076814
Abstract: Background Human landing collections are currently the standard method for collecting onchocerciasis vectors in Africa and Latin America. As part of the efforts to develop a trap to replace human landing collections for the monitoring and surveillance of onchocerciasis transmission, comprehensive evaluations of several trap types were conducted to assess their ability to collect Simulium ochraceum sensu lato, one of the principal vectors of Onchocerca volvulus in Latin America. Methodology/Principal Findings Diverse trap designs with numerous modifications and bait variations were evaluated for their abilities to collect S. Ochraceum s.l. females. These traps targeted mostly host seeking flies. A novel trap dubbed the “Esperanza window trap” showed particular promise over other designs. When baited with CO2 and BG-lure (a synthetic blend of human odor components) a pair of Esperanza window traps collected numbers of S. Ochraceum s.l. females similar to those collected by a team of vector collectors. Conclusions/Significance The Esperanza window trap, when baited with chemical lures and CO2 can be used to collect epidemiologically significant numbers of Simulium ochraceum s.l., potentially serving as a replacement for human landing collections for evaluation of the transmission of O. volvulus.
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