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Search Results: 1 - 10 of 465580 matches for " A. Aguilar-Hernandez "
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Biologic Development of Triatoma mexicana (Herrich-Schaeffer 1848) (Hemiptera: Reduviidae: Triatominae) under Laboratory Conditions
M.A. Becerril-Flores,A. Aguilar-Hernandez,J.L. Imbert-Palafox
International Journal of Tropical Medicine , 2012,
Abstract: Triatoma mexicana is one of the triatomine species whose biologic development is yet unknown, but it is frequently reported to be infected by Trypanosoma cruzi. In this research, we explore the life cycle and reproductive and feeding patterns of T. mexicana under laboratory conditions. Ten female and 12 male insects were collected to make up a artificial colony. The deposited eggs were maintained in the laboratory under 3 different conditions: 27 C and 66% humidity, 26 C and 35% humidity and 19 C and 45% humidity (these last were room temperature and humidity). Nymph and adult insects were fed on CD-1 mice and chicken once a week in order to study the alimentary preference of this triatomine species. Our observations were that 71.5% of successful hatching took place at 27 C and 66% humidity, therefore were the better environmental conditions for T. mexicana. Out of successfully hatched ones, 8% survived till adulthood, in which 2.5% were males and 5.5% were females, at the end of 338.66 35.38 days. In the adult phase, the insects survived between 100 and 190 days. In 1st to 4th instars, T. mexicana was fed for 1-3 times; in 5th instar for 1-4 times and in adulthood for 3-7 times. Each feeding occurred at an interval of 15-34 days. The morphologic characteristics of every instar phase are described by photographs. Through this research, biologic cycle and survival conditions of T. mexicana were explored for the first time.
Three-dimensional aspects of fluid flows in channels. II. Effects of Meniscus and Thin Film regimes on Viscous Fingers
R. Ledesma-Aguilar,I. Pagonabarraga,A. Hernandez-Machado
Physics , 2007, DOI: 10.1063/1.2801513
Abstract: We perform a three-dimensional study of steady state viscous fingers that develop in linear channels. By means of a three-dimensional Lattice-Boltzmann scheme that mimics the full macroscopic equations of motion of the fluid momentum and order parameter, we study the effect of the thickness of the channel in two cases. First, for total displacement of the fluids in the channel thickness direction, we find that the steady state finger is effectively two-dimensional and that previous two-dimensional results can be recovered by taking into account the effect of a curved meniscus across the channel thickness as a contribution to surface stresses. Secondly, when a thin film develops in the channel thickness direction, the finger narrows with increasing channel aspect ratio in agreement with experimental results. The effect of the thin film renders the problem three-dimensional and results deviate from the two-dimensional prediction.
Three-dimensional aspects of fluid flows in channels. I. Meniscus and Thin Film regimes
R. Ledesma-Aguilar,A. Hernandez-Machado,I. Pagonabarraga
Physics , 2007, DOI: 10.1063/1.2801511
Abstract: We study the forced displacement of a fluid-fluid interface in a three-dimensional channel formed by two parallel solid plates. Using a Lattice-Boltzmann method, we study situations in which a slip velocity arises from diffusion effects near the contact line. The difference between the slip and channel velocities determines whether the interface advances as a meniscus or a thin film of fluid is left adhered to the plates. We find that this effect is controlled by the capillary and Peclet numbers. We estimate the crossover from a meniscus to a thin film and find good agreement with numerical results. The penetration regime is examined in the steady state. We find that the occupation fraction of the advancing finger relative to the channel thickness is controlled by the capillary number and the viscosity contrast between the fluids. For high viscosity contrast, Lattice-Boltzmann results agree with previous results. For zero viscosity contrast, we observe remarkably narrow fingers. The shape of the finger is found to be universal.
The Effect of Adding Spent Hen Meal in Pig Feeding
S.G. Bravo Jimenez,J.R. Orozco-Hernandez,J.J. Uribe-Gomez,V.O. Fuentes Hernandez,A. Aguilar de la Torre,O.H. Navarro-Gonzalez
Research Journal of Biological Sciences , 2012,
Abstract: The search for alternative proteinaceous ingredients for monogastric animals is a constant task for the producer. The continuous renewal of hen population in the poultry industry, generates a protein source of aminoacids that can be used in pig feeding. The objective of the trial was to assess the effect of increasing levels of a poultry by-product meal in pig feeding, from weaning to market weight. Eighty newly weaned pigs were separated into 5 animal group to assess the addition of 0, 2.5, 5 and 7.5% (dry matter basis) of a Spent Hen by-product Meal (SHM) to a sorghum-soybean meal in pigs. The intake was daily measured and the weight gain was calculated using initial and final measurements. The initial weight was used as co-variable for the gain. Most of the production parameters were negatively affected with the addition of SHM (p<0.05). Increasing the SHM in the diet may affect negatively some of the production parameters in pigs.
Liana Abundance, Diversity, and Distribution on Barro Colorado Island, Panama
Stefan A. Schnitzer, Scott A. Mangan, James W. Dalling, Claire A. Baldeck, Stephen P. Hubbell, Alicia Ledo, Helene Muller-Landau, Michael F. Tobin, Salomon Aguilar, David Brassfield, Andres Hernandez, Suzanne Lao, Rolando Perez, Oldemar Valdes, Suzanne Rutishauser Yorke
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052114
Abstract: Lianas are a key component of tropical forests; however, most surveys are too small to accurately quantify liana community composition, diversity, abundance, and spatial distribution – critical components for measuring the contribution of lianas to forest processes. In 2007, we tagged, mapped, measured the diameter, and identified all lianas ≥1 cm rooted in a 50-ha plot on Barro Colorado Island, Panama (BCI). We calculated liana density, basal area, and species richness for both independently rooted lianas and all rooted liana stems (genets plus clones). We compared spatial aggregation patterns of liana and tree species, and among liana species that varied in the amount of clonal reproduction. We also tested whether liana and tree densities have increased on BCI compared to surveys conducted 30-years earlier. This study represents the most comprehensive spatially contiguous sampling of lianas ever conducted and, over the 50 ha area, we found 67,447 rooted liana stems comprising 162 species. Rooted lianas composed nearly 25% of the woody stems (trees and lianas), 35% of woody species richness, and 3% of woody basal area. Lianas were spatially aggregated within the 50-ha plot and the liana species with the highest proportion of clonal stems more spatially aggregated than the least clonal species, possibly indicating clonal stem recruitment following canopy disturbance. Over the past 30 years, liana density increased by 75% for stems ≥1 cm diameter and nearly 140% for stems ≥5 cm diameter, while tree density on BCI decreased 11.5%; a finding consistent with other neotropical forests. Our data confirm that lianas contribute substantially to tropical forest stem density and diversity, they have highly clumped distributions that appear to be driven by clonal stem recruitment into treefall gaps, and they are increasing relative to trees, thus indicating that lianas will play a greater role in the future dynamics of BCI and other neotropical forests.
Effect of Trisodium Citrate on the Properties of Electrodeposited Cu2ZnSnS4 (CZTS) Layers on ZnS Thin Films Using a 2-Electrode Method  [PDF]
Gustavo A. Silva Hernandez, Ajith R. Weerasinghe
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.88021
Abstract: Electrodeposition of CZTS thin films on ZnS was carried using a 2-electrode method to fabricate superstrate structure solar cells. A comprehensive study was performed on the effects of trisodium citrate on the CZTS electrolyte bath. In the present investigation, it is demonstrated that using a CZTS electrolyte with a concentration of 0.2 M trisodium citrate yields CZTS thin films with an electronic bandgap of 1.52 eV, a p-type nature, and good uniformity, which are all results desired for the fabrication of thin film solar cells. Characterization was performed using UV-Vi-IR optical absorption, SEM imaging, Raman spectrometry, and photoelectrochemical cells conducted for electronic bandgap, morphology, chemical composition, and semiconductor conductivity, respectively.
Dynamics of gravity driven three-dimensional thin films on hydrophilic-hydrophobic patterned substrates
Rodrigo Ledesma-Aguilar,Aurora Hernandez-Machado,Ignacio Pagonabarraga
Physics , 2010,
Abstract: We investigate numerically the dynamics of unstable gravity driven three-dimensional thin liquid films on hydrophilic-hydrophobic patterned substrates of longitudinal stripes and checkerboard arrangements. The thin film can be guided preferentially on hydrophilic longitudinal stripes, while fingers develop on adjacent hydrophobic stripes if their width is large enough. On checkerboard patterns, the film fingering occurs on hydrophobic domains, while lateral spreading is favoured on hydrophilic domains, providing a mechanism to tune the growth rate of the film. By means of kinematical arguments, we quantitatively predict the growth rate of the contact line on checkerboard arrangements, providing a first step towards potential techniques that control thin film growth in experimental setups.
Position Operators and Center of Mass: New Perspectives
Pedro Aguilar,Chryssomalis Chryssomalakos,Hector Hernandez Coronado,Elias Okon
Physics , 2013, DOI: 10.1142/S0217751X13501467
Abstract: After reviewing the work of Pryce on Center-of-Mass (CoM) definitions in special relativity, and that of Jordan and Mukunda on position operators for relativistic particles with spin, we propose two new criteria for a CoM candidate: associativity, and compatibility with the Poisson bracket structure. We find that they are not satisfied by all of Pryce's definitions, and they also rule out Dixon's CoM generalization to the curved spacetime case. We also emphasize that the various components of the CoM position do not commute among themselves, in the general case, and thus provide a natural entry point to the arena of noncommutative spacetime, without the ad-hoc assumptions of the standard paradigm.
Growth saturation of unstable thin films on transverse-striped hydrophilic-hydrophobic micropatterns
Rodrigo Ledesma-Aguilar,Aurora Hernandez-Machado,Ignacio Pagonabarraga
Physics , 2011,
Abstract: Using three-dimensional numerical simulations, we demonstrate the growth saturation of an unstable thin liquid film on micropatterned hydrophilic-hydrophobic substrates. We consider different transverse-striped micropatterns, characterized by the total fraction of hydrophilic coverage and the width of the hydrophilic stripes. We compare the growth of the film on the micropatterns to the steady states observed on homogeneous substrates, which correspond to a saturated sawtooth and growing finger configurations for hydrophilic and hydrophobic substrates, respectively. The proposed micropatterns trigger an alternating fingering-spreading dynamics of the film, which leads to a complete suppression of the contact line growth above a critical fraction of hydrophilic stripes. Furthermore, we find that increasing the width of the hydrophilic stripes slows down the advancing front, giving smaller critical fractions the wider the hydrophilic stripes are. Using analytical approximations, we quantitatively predict the growth rate of the contact line as a function of the covering fraction, and predict the threshold fraction for saturation as a function of the stripe width.
Pareto front for chemotherapy schedules
A. Barrea,M. Hernandez
Applied Mathematical Sciences , 2012,
Abstract:
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