Artículos y presentaciones en Congresos
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Examinando Artículos y presentaciones en Congresos por Autor "Arizaga, Ricardo"
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Acceso Abierto Analysis Of Bacterial Chemotactic Response Using Dynamic Laser Speckle(2009) Murialdo, Silvia Elena; Sendra, Gonzalo Hernán; Passoni, Lucía I.; Arizaga, Ricardo; Gonzalez, Jorge Froilan; Rabal, Héctor J.; Trivi, Marcelo RicardoChemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle or biospeckle to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis. - Artículo
Acceso Abierto Assessment of Seed Viability by Laser Speckle Techniques(2003) Braga, Roberto A.; Dal Fabbro, Inácio M.; Borem, Flávio M.; Rabelo, Giovanni; Arizaga, Ricardo; Rabal, Héctor J.; Trivi, Marcelo RicardoThis work presents a new technique as a potential methodology to analyse seeds. The technology is known as dynamic speckle, or biospeckle, an optical phenomenon produced when active materials, such as biological tissue, are illuminated by laser light. In the present work, the biological activity of seed tissues has been inferred from quantitative and qualitative measurements of their speckle activity. The aim is to show that the biospeckle technique has a potential as a methodology to assess seed viability. One aspect that needs to be investigated is how the water content in the seeds affects bio-speckle activity. An experiment has been performed to determine the effect of humidity in the results. Seed activity for different levels of humidity was determined using quantitative and qualitative methods. Also, in others experiments, viable and non-viable seeds with different specific humidity levels could be classified using the same technique. - Artículo
Acceso Abierto Decomposition of biospeckle images in temporary spectral bands(2005) Sendra, Gonzalo Hernán; Arizaga, Ricardo; Rabal, Héctor J.; Trivi, Marcelo RicardoWe present a method of analysis of images of dynamic speckle based on the filtering in frequency bands of the temporary history of each pixel. Butterworth filters are applied to the temporary evolution, and different images are constructed showing the energy in each frequency band. Different degrees of activity of the sample in study, presumably attributed to different origins, are found. The method is exemplified with images of bruising damage in fruits and of biological activity in germinating corn seeds. It is found that the activity in the bruised region of an apple differs from the activity of healthy regions in a certain characteristic frequency range. The activity of the embryo can also be distinguished from that of the endosperm in corn seeds during germination. - Artículo
Acceso Abierto Fully digital encryption technique(2003) Arizaga, Ricardo; Henao Henao, Rodrigo de Jesús; Torroba, RobertoWe propose an alternative fully digital encryption technique based on using the Fourier transform of the original object to be processed and a speckled reference wave as encryption mask. Once encrypted, the Fourier transform spectrum of the object is holographically stored. The original data recovering is performed by digital reconstruction using the same encryption mask, which is also holographically stored. Quality of reconstructed data is evaluated as a function of the sensed encrypted data. Computer simulations and experimental results are presented to demonstrate the method. - Artículo
Acceso Abierto Light-in-flight digital holography display(1994) Rabal, Héctor J.; Pomarico, Juan; Arizaga, RicardoWe present a digital speckle-pattern interferometric setup that can be operated at TV frame rates (30 ms) to display the locus of the points at which the optical-path difference between the reference and object beams is within the coherence length. Experimental results are shown. - Artículo
Acceso Abierto Macrometrología Láser: Control de movimientos y alineación en los grupos turbocompresores del Complejo General Cerri de Gas del Estado(Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICBA), 1984) Arizaga, Ricardo; Gallardo, R.; Laquidara, Aníbal Pablo; Tocho, Jorge Omar; Gallardo, Mario; Duchowicz, Ricardo; Garbocci, M.; Ranea Sandoval, Héctor F.A solicitud de la Empresa Gas del Estado, el CIOp real zó una serie de medidas Ópticas empleando láseres de baja potencia, para determinar el estado de alineación de los equipos turbocompresores instalados en la Planta de Separación de Etano, Propano, Butano e Hidrocarburos Superiores del Complejo General Cerri . - Informe técnico
Acceso Abierto Medición por un método óptico del desplazamiento del extremo de obenques en el puente Zárate-Brazo Largo(1997) Gallardo, Mario; Rabal, Héctor J.; Sicre, Enrique Eduardo; Arizaga, Ricardo; Pomarico, Juan; Bredice, Fausto OsvaldoEl dispositivo óptico utilizado para medir el desplazamiento (en las direcciones horizontal y vertical) del extremo del obenque se esquematiza en la Figura (pag. 4). La unidad emisora, fija próxima al obenque, consiste en un diodo láser visible (de longitud de onda: 670nm y potencia: 1OmW) cuya radiación se acopla a una guía de luz por fibras ópticas. Esta guía se divide en dos partes, proporcionando de este modo dos fuentes luminosas con una separación entre sí de: d0 = 380 mm, en la dirección vertical En la zona del puente elegida como "punto fijo de referencia", distante a unos 170m del obenque a medir, se colocó la unidad detectora. Esta consiste en un telescopio reflector de distancia focal: f = 210cm, y apertura: a = 18cm, que forma una imagen demagnificada de las fuentes luminosas sobre un arreglo detector CCD ("charge-coupled-device") con una resolución espacial de 756 x 581 pixels. La salida de video de la cámara CCD, correspondiente a las sucesivas imágenes detectadas, se almacenó en una grabadora de video (VCR). La cámara CCD se ubicó de forma que los desplazamientos verticales de la unidad emisora coincidieran con la dirección horizontal, de mayor tamaño, del monitor de observación. A continuación se describe el procedimiento utilizado para efectuar las mediciones. - Artículo
Acceso Abierto Optical correlation based on the fractional Fourier transform(1997) Granieri, Sergio Carlos; Arizaga, Ricardo; Sicre, Enrique EduardoSome properties of optical correlation based on the fractional Fourier transform are analyzed. For a particular set of fractional orders, a filter is obtained that becomes insensitive to scale variations of the object. An optical configuration is also proposed to carry out the fractional correlation in a flexible way, and some experimental results are shown. - Artículo
Acceso Abierto Principios de fotometría: instrumentos de medición (parle I)(1977) Arizaga, RicardoCuando se desea evaluar la intensidad de cualquier fuente luminosa, es necesario contar con un standard e patrón de intensidad y un instrumento que permita realizar la comparación entre ambas. Un fotómetro, aunque no mide directamente Intensidades lumi· nosas, nos permite obtener valores cuantitativos de la Intensidad de una fuente en base a la iluminación que ésta produce. Para esto se hace ne· cesarlo conocer qué relación existe entre la Intensidad de una fuente la iluminación que ella produce. - Artículo
Acceso Abierto Principios de fotometría: instrumentos de medición (parle II)(1977) Arizaga, RicardoSe designa con este nomre a todo instrumento que utiliza como detector algún elemento fotosensible. Este tipo de detectores transforman la luz en electricidad, transformación que puede realizarse directamente o indirectamente a través de una doble transformación, de energía luminosa a términa y de térmica a eléctrica. (Párrafo extraído a modo de resumen) - Artículo
Acceso Abierto Pseudocoloring method using two different spatial modulations(1982) Bolognini, Néstor; Sicre, Enrique Eduardo; Arizaga, Ricardo; Rabal, Héctor J.; Garavaglia, Mario J.Pseudocoloring of gray level information is a technique for introducing false colors in a black-and-white transparency. The importance of this operation is based on the human eye’s ability to distinguish different colors better than gray levels. In the last few years several pseudocoloring optical methods have been proposed. Furthermore, the pseudocoloring technique has been extended to encode image spatial spectral bands and holographic interferometric fringe patterns. In a recent paper we presented a further generalization of pseudocoloring for assigning false colore to depth level contours of 3-D objects. In this Letter we propose a modification of the pseudocoloring speckle method for storing two images in a single recording material in such a way that each recorded image has a different spatial modulation. Therefore, in a decoding step, on illuminating the processed plate with a white light source, there exist two wavelength values for which the spatial spectra of both encoded images are centered at the same spatial frequency value. Thus, an additive mixture of both images is produced with a pseudocoloring effect which depends on the two mentioned wavelengths. - Artículo
Acceso Abierto Real-time white light pseudocolor density encoder(1982) Arizaga, Ricardo; Bolognini, Néstor; Rabal, Héctor J.; Sicre, Enrique Eduardo; Garavaglia, Mario J.A simple method for pseudocolor encoding of gray level information is proposed. It is based on the real-time addition of the positive and negative images of an object transparency, each one obtained in a different color. Conventional white light lamps with adequate color filters are used. Some experimental results are shown. - Artículo
Acceso Abierto Sistema de procesamiento de valores triestímulos para el cálculo de coordenadas cromáticas CIE, longitudes de onda y pureza(1980) Arizaga, Ricardo; Biondini, RicardoEn la bibliogradfía existen trabajos que describen sistemas, tanto para transformar coordenadas como para calcular longitud de onda dominante y pureza de excitación(1,2). Estos emprean técnicas de exploración de tablas, tanto para los cálculos de longitud de onda como de la pureza, obteniendo sus resultados por aproximación. - Artículo
Acceso Abierto Speckle activity images based on the spatial variance of the phase(2006) Rabal, Héctor J.; Cap, Nelly Lucía; Trivi, Marcelo Ricardo; Arizaga, Ricardo; Federico, Alejandro; Galizzi, Gustavo E.; Kaufmann, Guillermo H.We propose the display of the local spatial variance of the temporal variations of the phase as an activity descriptor in dynamic speckle images. The spatial autocorrelation of the speckle intensity is calculated in sliding windows, and an estimation of the variance of the phase variations in each region of the sample is determined. The activity images obtained in this way depict some interesting features and in some cases they could be related to physical magnitudes in the samples. A simulation is presented, and examples corresponding to usual study cases are also shown, namely, fruit bruising and paint drying.