4,600 research outputs found
Raul Fernandez & Gilbert Gonzalez
No full textOral history between Raul Fernandez, Professor Emeritus of Chicano/Latino Studies and Gilbert Gonzalez, Professor Emeritus of Chicano/Latino Studies. Fernandez’ previous positions include Chair of the Department of Chicano/Latino Studies. Gonzalez’ previous positions include Director of the UCI Labor Studies Program
BOLIVIA / Raul SHAW and LOS PEREGRINOS
No full textComprend : PALMERAS / folklore - arr. Gilberto ROJAS - DESILUSION / BARRIOS et SHAW - POLLERITA / folklore - arr. par Raul SHAW - NOCHE CHAPACA / folklore - arr. Raul SHAW - BORRACHITO LADRON / Raul SHAW - DIABLITO LUCIFER / Mario BARRIOS - ACUARELA BOLIVIANA / folklore - arr. Alex SHAW - NARANJITA / Tito VELIZ - DIABLADA TRADICIONAL / folklore - arr. A. SHAW - JENECHEYRU / Gilberto ROJAS - PRENDA QUERIDA / Gilberto ROJAS - RIE CORAZON / folklore - arr. A. SHAWBnF-Partenariats, Collection sonore - BelieveContient une table des matière
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Friends, Family gather at Dr. Clotilde Garcia's home honoring Raul Morin (photograph)
No full textFriends, Family gather at Dr. Clotilde Garcia's home honoring Raul Morin. Author of the book “Among the Valient.
Wall repulsion during electrophoresis: testing the theory of concentration-polarization electro-osmosis
No full textWe experimentally study the repulsion of charged microscopic particles with the channel walls during electrophoresis in microfluidic devices. For low frequencies of the electric fields (< 10 kHz), this repulsion is mainly due to the hydrodynamic interaction caused by the flow vortices that arise from the slip velocity induced by the electric field on the particle surface, as shown in a recent publication [Fernandez-Mateo et al., Physical Review Letters, 128, 074501, (2022)]. The maximum slip velocity on the particle surface is inferred from measurements of wall-particle separation. Importantly, this procedure allows us to infer very small slip velocities that otherwise are too weak to be measured directly. Data at small electric field amplitudes (E0) agree with theoretical predictions using the model of Concentration Polarization Electroosmosis (CPEO), which has recently been proposed as the mechanism behind the flow vortices on the surface of the particles. Data for higher electric fields show that the predictions of the CPEO theory for weak electric fields are not valid beyond E0 ∼ 60 kV/m. Additionally, we also show that, for sufficiently strong electric fields, the quadrupolar flow structures become disrupted, leading to a weaker wall repulsion
Concentration polarization electroosmosis: Theory and applications
No full textElectrokinetics plays a significant role in microfluidic and Lab on Chip systems. Over the last 25 years, the understanding of electrokinetic phenomena has matured considerably, leading to new ways of manipulating fluids and particles on the micro-scale efficiently. This thesis describes experimental characterization and theoretical modelling of a new AC electrokinetic effect termed Concentration-Polarization Electroosmosis, or CPEO. This phenomenon describes steady-state electroosmotic flows that occur around charged insulating micro-structures in the presence of a low-frequency AC electric field. CPEO arises from concentration polarization (CP) and is driven by surface conductance, meaning that the characteristic time is governed by diffusion, t~a^2/D (a is the length scale and D the diffusion constant of the electrolyte ions). As a result, CPEO is observed at low frequencies, e.g. around 300 Hz and below for a 1 μm-sized object immersed in a low-conductivity KCl electrolyte. In this thesis CPEO flows are studied around features fabricated within microfluidic channels, such as pillars and constrictions. A theoretical framework is presented based on recent analytical approaches that provided macroscale boundary conditions for the electric and hydrodynamic problem; these are extended for the case of AC fields. A linear expansion for small Dukhin numbers gives an analytical description for the flows, which is found to be in excellent agreement with experimental observations. Further description for arbitrary Dukhin numbers (large surface conductance) and small electric field magnitudes predicts CPEO flows around charged microparticles. New image analysis methods allow experimental measurements of CPEO on a smaller scale, matching theoretical predictions. It is known that during electrophoresis, particles are repelled from the channel walls. This behaviour is magnified at low frequencies and low conductivities, something that has been reported in the literature but remains unexplained. For these experimental conditions, CPEO flows around suspended particles in microchannels predict hydrodynamic wall-particle repulsive interactions. Experiments confirm that the observed repulsion is caused by quadrupolar fluid flows around the particles, and a detailed characterization has demonstrated that the phenomenon is due to CPEO. Given the known dependence of these flows upon the particle size and surface charge (zeta-potential), CPEO was exploited to fractionate different polystyrene particles. The thesis also describes novel procedures and techniques developed to deliver the main results of the project. A simplified method was discovered for measuring the zeta potential of a microfluidic channel with improved precision. Also, a user-friendly software has been developed for rapid particle detection called Particle Finder. This tool performs automated image analysis of large numbers of images allowing rapid analysis of particles moving in a continuous flow. Finally, the thesis describes how the ideas of CPEO can be used to explain the low-frequency behaviour of an electrokinetic biased Deterministic Lateral Displacement (DLD) device, where the CPEO flows were initially observed. Numerical simulations of particle trajectories were made considering the wall repulsion from the pillars in the DLD array. These show agreement with previous experiments, providing a full quantitative understanding of the DLD separation system for all frequencies and conductivities
Análisis y evaluación de propiedades físico hídrica de los suelos
Full text linkTodos los capítulos de este manual tratan sobre los problemas que de una u otra forma generan limitaciones en las propiedades físico-hídrica de los suelos, es decir, la capacidad de los mismos para soportar el crecimiento de los cultivos. Son pocos los textos publicados en castellano que recopilan no sólo la información, sino también los conceptos básicos de la dinámica del agua sobre los sistemas de producción a partir del análisis y evaluación de indicadores físicos-hídricos de los suelos. Por lo tanto, esta publicación permite que el lector tenga una visión general y completa sobre esta temática.EEA AnguilFil: Quiroga, Alberto Raul. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; Argentina. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Fernandez, Romina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; ArgentinaFil: Alvarez, Cristian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; Argentin
Description of immature stages of Berosus alternans Brullé (Coleoptera: Hydrophilidae)
No full textEgg cases, larvae and pupae of Berosus alternans Leach, 1817 are described from Florencio Vareta, Buenos Aires province, Argentina. Diagnostic characters of externa! morphology are discussed, and comparisons with other known Berosus, are made. A key to different instar larvae is provided.Fil: Campos, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; ArgentinaFil: Fernandez, Liliana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; Argentin
La fertilización nitrogenada en el centeno utilizando como cultivo de cobertura afecta el rendimiento de maíz
Full text linkEl objetivo fue evaluar la incidencia de distintas dosis de fertilización nitrogenada sobre la producción de materia seca (MS) de centeno utilizado como CC y sobre la productividad del maíz siguiente.EEA AnguilFil: Raposo, Juan Manuel. Facultad de Agronomía. Universidad Nacional de La Pampa; ArgentinaFil: Fernandez, Romina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; ArgentinaFil: Quiroga, Alberto Raul. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; Argentina. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentin
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