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Search Results: 1 - 10 of 591277 matches for " A. Jaramillo-Nú?ez "
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Construcción de un inclinómetro óptico
Jaramillo-Nú?ez, A;Lucero-álvarez, M;
Revista mexicana de física , 2007,
Abstract: in this work an optical instrument for measuring tilt is described. the device is compact, requires no special handling and can measure variations in tilt of the order of 0.5 arcsec, although this value can be suitably modified by changing the setup parameters. the instrument was developed as a tiltmeter using a liquid surface as reference surface. the inclination is obtained by measuring the longitudinal displacement of a laser beam after being reflected from the surface of the liquid. the application of the instrument for measuring the tilt of the spindle of a polishing machine of large dimensions is presented.
Medidor de distancias con referencia interferometrica
Jaramillo-Nú?ez, A.;Pérez-Meza, M.;
Revista mexicana de física , 2010,
Abstract: an instrument for measuring distances is described. its functioning is based in a lateral shearing interferometer and the observation of the collimation of a laser beam. two interference patterns of straight fringes are used to measure the distance and only when the fringes are parallels the measurement is considered. results obtained and related with resolution and uncertainty of measurement of the instrument are presented.
Construcción de un inclinómetro óptico
A. Jaramillo-Nú?ez,M. Lucero-álvarez
Revista mexicana de física , 2007,
Abstract: En este trabajo se describen la construcción, caracterización y aplicación de un instrumento óptico para medir inclinaciones. El instrumento es de fácil manejo, de no contacto, y puede medir inclinaciones del orden de 0.5 segundos de arco en un rango de 14 minutos de arco. La precisión de las mediciones puede ser modificada cambiando apropiadamente algunos parámetros del arreglo. El instrumento fue desarrollado como un inclinometro usando como referencia la superficie horizontal de un líquido, además, la inclinación se obtiene midiendo con un detector sensible a la posición el desplazamiento que sufre un haz de láser después de reflejarse en la superficie del líquido. Se muestra la aplicación del instrumento en la medición de la inclinación del husillo de una máquina pulidora de grandes dimensiones.
Medidor de distancias con referencia interferometrica
A. Jaramillo-Nú?ez,M. Pérez-Meza
Revista mexicana de física , 2010,
Abstract: En este trabajo se describe un instrumento óptico para medir distancias. Su funcionamiento está basado en un interferómetro de desplazamiento lateral y en la observación del paralelismo entre dos patrones de franjas rectas. Cálculos realizados en computadora muestran las distancias que se pueden medir, aunque en la práctica no es posible llegar a las predicciones teóricas ya que el instrumento requiere una calibración previa, por lo que el rango de medición que se analiza es sólo de 3000 mm. Debido a que la distancia se obtiene desplazando una lente, la resolución e incertidumbre de medición del instrumento se ven afectadas por este elemento óptico.
Transfer of Machined Patterns on an Aluminum Plate to Pyrex Glass Using Reactive Ion Etching SF6 Plasma without Masks  [PDF]
Carlos M. Ortiz-Lima, Fernando J. Qui?ones-Novelo, Alberto Jaramillo-Nú?ez, Jorge Castro-Ramos
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2014, DOI: 10.4236/jsemat.2014.45030
Abstract:

A method for etching the surface of a Pyrex glass substrate using the Reactive Ion Etching process without the use of masks is reported. Variations in the machined surface on an auxiliary plate, manufactured in aluminum and placed below a Pyrex glass slide, were transferred to the upper surface of the substrate. SF6 as etching gas and low pressure chamber to promote the increase of mean free path of ions were used. Two etching ratios were found, general, that affects the entire surface of the substrate, and differential, which generates the relief on the surface of the glass. Differential etching depth showed a linear behavior with respect to time; the mean differential etching rate obtained was 43 nm/min. The same phase between the auxiliary plate machining and the etched pattern on the substrate is preserved. With this technique it was possible to manufacture convex and concave surfaces; some examples are given. The arithmetic mean roughness achieved with the proposed method was found to be N1 class, ideal for the development of optical corrector plates.

On the critical dipole moment in one-dimension
Benjamín Jaramillo,H. N. Nú?ez-Yépez,A. L. Salas-Brito
Physics , 2007,
Abstract: We calculate the minimum magnitude an electric dipole must have for a 1D system, interacting through the dipole, to support bound states.
A simple inquiry on the critical electric dipole moment in one space dimension
Jaramillo, B.;Nú?ez-Yépez, H.N.;Salas-Brito, A.L.;
Revista mexicana de física E , 2010,
Abstract: the magnitude of an electric dipole moment must be larger or equal to a certain critical value to support bound states. this is not a widely known fact that nevertheless is easy to understand on heuristic terms and relatively easy to calculate. this critical dipole moment, , has been calculated in 2 and 3 dimensions. it has been ascertained that it does not exist in one dimension or, at least, that it is not computable. in this work, after giving simple arguments on the existence of this critical moment, we compute in one dimension.
A simple inquiry on the critical electric dipole moment in one space dimension
B. Jaramillo,H.N. Nú?ez-Yépez,A.L. Salas-Brito
Revista mexicana de física E , 2010,
Abstract: The magnitude of an electric dipole moment must be larger or equal to a certain critical value to support bound states. This is not a widely known fact that nevertheless is easy to understand on heuristic terms and relatively easy to calculate. This critical dipole moment, , has been calculated in 2 and 3 dimensions. It has been ascertained that it does not exist in one dimension or, at least, that it is not computable. In this work, after giving simple arguments on the existence of this critical moment, we compute in one dimension. El valor de un momento dipolar eléctrico debe ser mayor o igual a un valor crítico para que admita estados ligados. Este no muy conocido hecho puede comprenderse en forma muy simple y su valor calculado en forma relativamente simple como lo hacemos en este trabajo. Se ha calculado el momento crítico en 2 y 3 dimensiones y se ha sugerido que no existe en una dimensión o que, al menos, no se le puede calcular. Damos argumentos simples para argüir su existencia y lo calculamos exactamente en una dimensión.
Activation of nucleus accumbens NMDA receptors differentially affects appetitive or aversive taste learning and memory
Luis Nú?ez-Jaramillo,Belén Burgue?o-Zú?iga,María I. Miranda
Frontiers in Behavioral Neuroscience , 2012, DOI: 10.3389/fnbeh.2012.00013
Abstract: Taste memory depends on motivational and post-ingestional consequences; thus, it can be aversive (e.g., conditioned taste aversion, CTA) if a novel, palatable taste is paired with visceral malaise, or it can be appetitive if no intoxication appears after novel taste consumption, and a taste preference is developed.The nucleus accumbens (NAc) plays a role in hedonic reactivity to taste stimuli, and recent findings suggest that reward and aversion are differentially encoded by the activity of NAc neurons. The present study examined whether the requirement for N-methyl-D-aspartate (NMDA) receptors in the NAc core during rewarding appetitive taste learning differs from that during aversive taste conditioning, as well as during retrieval of appetitive vs. aversive taste memory, using the taste preference or CTA model, respectively. Bilateral infusions of NMDA (1 μg/μl, 0.5 μl) into the NAc core were performed before acquisition or before retrieval of taste preference or CTA. Activation of NMDA receptors before taste preference training or CTA acquisition did not alter memory formation. Furthermore, NMDA injections before aversive taste retrieval had no effect on taste memory; however, 24 h later, CTA extinction was significantly delayed. Also, NMDA injections, made before familiar appetitive memory retrieval, interrupted the development of taste preference and produced a preference delay 24 h later. These results suggest that memory formation for a novel taste produces neurochemical changes in the NAc core that have differential requirements for NMDA receptors during retrieval of appetitive or aversive memory.
Ciclo gonadal del chorito Mytilus chilensis (Bivalvia: Mytilidae) en dos localidades del sur de Chile
Oyarzún,Pablo A; Toro,Jorge E; Jaramillo,Roberto; Gui?ez,Ricardo; Briones,Carolina; Astorga,Marcela;
Latin american journal of aquatic research , 2011,
Abstract: a qualitative and quantitative analysis was carried out of the gonadal cycle of the bivalve mytilus chilensis from chaihuín and yal bay, southern chile, between october 2007 and june 2008. four gametogenic stages were determined using histological analysis of the gonads, and quantitative estimates were made of the gametic volume fraction (vfg), percentage of inter follicular connective tissue, and the gonadosomatic index (ig). the quantitative analysis (vfg) was the best indicator of spawning. two spawning events, one in october and one in march, were observed simultaneously in both sexes of mussels from chaihuín. however, for specimens from bahía yal, four spawning events were registered, principally from march to june (autumn), when the water temperature decreased. the relationship between the ig and the gametogenic stages was very low, as was that between the ig and the percentage of mature oocytes. therefore, the ig is not a good indicator of spawning in this species. a re-evaluation of the ban period established for mytilus chilensis (1 november to 31 december) is suggested since most individuals from the populations studied mature mainly in october. at both sites, the percentage of connective tissue for the analyzed mussel individuals ranged between 15 and 70% of gonadal coverage. the results obtained in the present study showed differences in the reproductive cycles of mytilus chilensis between the sites sampled. these differences could be due to environmental differences (e.g. temperature) caused by the latitudinal gradient.
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