A LED based photometer for solid phase photometry: zinc determination in pharmaceutical preparation employing a multicommuted flow analysis approach

Neste trabalho é proposto um fotômetro baseado em LED (diodo emissor de luz) para fotometria em fase sólida. O fotômetro foi desenvolvido para permitir o acoplamento da fonte de radiação (LED) e do fotodetector direto na cela de fluxo, tendo um caminho óptico de 4 mm. A cela de fluxo foi preenchida com material sólido (C18), o qual foi utilizado para imobilizar o reagente cromogênico 1-(2-tiazolilazo)-2-naftol (TAN). A exatidão foi avaliada empregando dados obtidos através da técnica ICP OES (espectrometria de emissão por plasma indutivamente acoplado). Aplicando-se o teste-t pareado não foi observada diferença significativa em nível de confiança de 95%. Outros parâmetros importantes encontrados foram faixa de resposta linear de 0,05 a 0,85 mg L-1 Zn, limite de detecção de 9 µg L-1 Zn (n = 3), desvio padrão de 1,4 % (n = 10), frequência de amostragem de 36 determinações por h, e uma geração de efluente e consumo de reagente de 1,7 mL e 0,03 µg por determinação, respectivamente.

Multiple stellar populations in globular clusters with photometry and low resolution spectroscopy

Our view of Globular Clusters has deeply changed in the last decade. Modern spectroscopic and photometric data have conclusively established that globulars are neither coeval nor monometallic, reopening the issue of the formation of such systems. Their formation is now schematized as a two-step process, during which the polluted matter from the more massive stars of a first generation gives birth, in the cluster innermost regions, to a second generation of stars with the characteristic signature of fully CNO-processed matter. To date, star-to-star variations in abundances of the light elements (C, N, O, Na) have been observed in stars of all evolutionary phases in all properly studied Galactic globular clusters. Multiple or broad evolutionary sequences have also been observed in nearly all the clusters that have been observed with good signal-to-noise in the appropriate photometric bands. The body of evidence suggests that spreads in light-element abundances can be fairly well traced by photometric indices including near ultraviolet passbands, as CNO abundance variations affect mainly wavelengths shorter than ~400 nm owing to the rise of some NH and CN molecular absorption bands. Here, we exploit this property of near ultraviolet photometry to trace internal chemical variations and combined it with low resolution spectroscopy aimed to derive carbon and nitrogen abundances in order to maximize the information on the multiple populations. This approach has been proven to be very effective in (i) detecting multiple population, (ii) characterizing their global properties (i.e., relative fraction of stars, location in the color-magnitude diagram, spatial distribution, and trends with cluster parameters) and (iii) precisely tagging their chemical properties (i.e., extension of the C-N anticorrelation, bimodalities in the N content).

Tracking, photometry and spectroscopy of space debris: the Malindi, Loiano, Las Campanas and Cerro Tololo observation campaign results

The main purpose of my thesis has been the analysis of the space debris environment and their characterization through optical measurements. In particular I had the opportunity to contribute to the Italian Space Agency activities in space debris optical observation campaign and I cooperated directly with NASA Orbital Debris Program Office by working at the Astronomy Department of the University of Michigan for six months.

SALSA: a tool to estimate the stray light contamination for low-Earth orbit observatories

Stray light contamination reduces considerably the precision of photometric of faint stars for low altitude spaceborne observatories. When measuring faint objects, the necessity of coping with stray light contamination arises in order to avoid systematic impacts on low signal-to-noise images. Stray light contamination can be represented by a flat offset in CCD data. Mitigation techniques begin by a comprehensive study during the design phase, followed by the use of target pointing optimisation and post-processing methods. We present a code that aims at simulating the stray-light contamination in low-Earth orbit coming from reflexion of solar light by the Earth. StrAy Light SimulAtor (SALSA) is a tool intended to be used at an early stage as a tool to evaluate the effective visible region in the sky and, therefore to optimise the observation sequence. SALSA can compute Earth stray light contamination for significant periods of time allowing missionwide parameters to be optimised (e.g. impose constraints on the point source transmission function (PST) and/or on the altitude of the satellite). It can also be used to study the behaviour of the stray light at different seasons or latitudes. Given the position of the satellite with respect to the Earth and the Sun, SALSA computes the stray light at the entrance of the telescope following a geometrical technique. After characterising the illuminated region of the Earth, the portion of illuminated Earth that affects the satellite is calculated. Then, the flux of reflected solar photons is evaluated at the entrance of the telescope. Using the PST of the instrument, the final stray light contamination at the detector is calculated. The analysis tools include time series analysis of the contamination, evaluation of the sky coverage and an objects visibility predictor. Effects of the South Atlantic Anomaly and of any shutdown periods of the instrument can be added. Several designs or mission concepts can be easily tested and compared. The code is not thought as a stand-alone mission designer. Its mandatory inputs are a time series describing the trajectory of the satellite and the characteristics of the instrument. This software suite has been applied to the design and analysis of CHEOPS (CHaracterizing ExOPlanet Satellite). This mission requires very high precision photometry to detect very shallow transits of exoplanets. Different altitudes and characteristics of the detector have been studied in order to find the best parameters, that reduce the effect of contamination. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Application of stellar photometry to the analysis of microarray images

Improvements in the analysis of microarray images are critical for accurately quantifying gene expression levels. The acquisition of accurate spot intensities directly influences the results and interpretation of statistical analyses. This dissertation discusses the implementation of a novel approach to the analysis of cDNA microarray images. We use a stellar photometric model, the Moffat function, to quantify microarray spots from nylon microarray images. The inherent flexibility of the Moffat shape model makes it ideal for quantifying microarray spots. We apply our novel approach to a Wilms' tumor microarray study and compare our results with a fixed-circle segmentation approach for spot quantification. Our results suggest that different spot feature extraction methods can have an impact on the ability of statistical methods to identify differentially expressed genes. We also used the Moffat function to simulate a series of microarray images under various experimental conditions. These simulations were used to validate the performance of various statistical methods for identifying differentially expressed genes. Our simulation results indicate that tests taking into account the dependency between mean spot intensity and variance estimation, such as the smoothened t-test, can better identify differentially expressed genes, especially when the number of replicates and mean fold change are low. The analysis of the simulations also showed that overall, a rank sum test (Mann-Whitney) performed well at identifying differentially expressed genes. Previous work has suggested the strengths of nonparametric approaches for identifying differentially expressed genes. We also show that multivariate approaches, such as hierarchical and k-means cluster analysis along with principal components analysis, are only effective at classifying samples when replicate numbers and mean fold change are high. Finally, we show how our stellar shape model approach can be extended to the analysis of 2D-gel images by adapting the Moffat function to take into account the elliptical nature of spots in such images. Our results indicate that stellar shape models offer a previously unexplored approach for the quantification of 2D-gel spots. ^

"Si llega a ocurrir de vuelta los vecinos los matamos" : Anotaciones sobre entrevistas a vecinas de un ex CCD. Responsabilidad, justicia y/o derecho

Los últimos diez años han visto reaparecer la pregunta en torno al comportamiento de la sociedad civil durante la última dictadura. Esta pregunta, heterogénea en su interior -los comportamientos eclesiásticos, empresariales, partidarios, sindicales y, finalmente, del hombre común y corriente-, no es sin embargo una novedad en el campo argentino de los derechos humanos y la memoria: en la misma dictadura algunas voces preguntaron por ella (Rokkind, 2004:238). Este trabajo, enmarcado en nuestra tesis doctoral en curso sobre responsabilidad colectiva y pequeñas resistencias para con la última dictadura a partir de memorias de vecinos de CCD en sus representaciones literarias y cinematográficas en articulación con una etnografía sobre las vecindades de un ex CCD en particular, intentará volver sobre esta pregunta de dos modos distintos pero articulados. Por un lado, repasando dos trabajos clásicos sobre derecho transicional y responsabilidad de dos autores de destacada participación en el Juicio a las Juntas (Nino, 1997; MalamudGoti, 2000). Por el otro, rastreando el modo en que aquellas responsabilidades y justicias aparecen en dos entrevistas realizadas a vecinas de un ex CCD en particular, la Seccional 1o de Santa Rosa-La Pampa, durante nuestro trabajo de campo. En esta dirección intentará orientarse este trabajo

"Si llega a ocurrir de vuelta los vecinos los matamos" : Anotaciones sobre entrevistas a vecinas de un ex CCD. Responsabilidad, justicia y/o derecho

Los últimos diez años han visto reaparecer la pregunta en torno al comportamiento de la sociedad civil durante la última dictadura. Esta pregunta, heterogénea en su interior -los comportamientos eclesiásticos, empresariales, partidarios, sindicales y, finalmente, del hombre común y corriente-, no es sin embargo una novedad en el campo argentino de los derechos humanos y la memoria: en la misma dictadura algunas voces preguntaron por ella (Rokkind, 2004:238). Este trabajo, enmarcado en nuestra tesis doctoral en curso sobre responsabilidad colectiva y pequeñas resistencias para con la última dictadura a partir de memorias de vecinos de CCD en sus representaciones literarias y cinematográficas en articulación con una etnografía sobre las vecindades de un ex CCD en particular, intentará volver sobre esta pregunta de dos modos distintos pero articulados. Por un lado, repasando dos trabajos clásicos sobre derecho transicional y responsabilidad de dos autores de destacada participación en el Juicio a las Juntas (Nino, 1997; MalamudGoti, 2000). Por el otro, rastreando el modo en que aquellas responsabilidades y justicias aparecen en dos entrevistas realizadas a vecinas de un ex CCD en particular, la Seccional 1o de Santa Rosa-La Pampa, durante nuestro trabajo de campo. En esta dirección intentará orientarse este trabajo

"Si llega a ocurrir de vuelta los vecinos los matamos" : Anotaciones sobre entrevistas a vecinas de un ex CCD. Responsabilidad, justicia y/o derecho

Los últimos diez años han visto reaparecer la pregunta en torno al comportamiento de la sociedad civil durante la última dictadura. Esta pregunta, heterogénea en su interior -los comportamientos eclesiásticos, empresariales, partidarios, sindicales y, finalmente, del hombre común y corriente-, no es sin embargo una novedad en el campo argentino de los derechos humanos y la memoria: en la misma dictadura algunas voces preguntaron por ella (Rokkind, 2004:238). Este trabajo, enmarcado en nuestra tesis doctoral en curso sobre responsabilidad colectiva y pequeñas resistencias para con la última dictadura a partir de memorias de vecinos de CCD en sus representaciones literarias y cinematográficas en articulación con una etnografía sobre las vecindades de un ex CCD en particular, intentará volver sobre esta pregunta de dos modos distintos pero articulados. Por un lado, repasando dos trabajos clásicos sobre derecho transicional y responsabilidad de dos autores de destacada participación en el Juicio a las Juntas (Nino, 1997; MalamudGoti, 2000). Por el otro, rastreando el modo en que aquellas responsabilidades y justicias aparecen en dos entrevistas realizadas a vecinas de un ex CCD en particular, la Seccional 1o de Santa Rosa-La Pampa, durante nuestro trabajo de campo. En esta dirección intentará orientarse este trabajo

"Si llega a ocurrir de vuelta los vecinos los matamos" : Anotaciones sobre entrevistas a vecinas de un ex CCD. Responsabilidad, justicia y/o derecho

Los últimos diez años han visto reaparecer la pregunta en torno al comportamiento de la sociedad civil durante la última dictadura. Esta pregunta, heterogénea en su interior -los comportamientos eclesiásticos, empresariales, partidarios, sindicales y, finalmente, del hombre común y corriente-, no es sin embargo una novedad en el campo argentino de los derechos humanos y la memoria: en la misma dictadura algunas voces preguntaron por ella (Rokkind, 2004:238). Este trabajo, enmarcado en nuestra tesis doctoral en curso sobre responsabilidad colectiva y pequeñas resistencias para con la última dictadura a partir de memorias de vecinos de CCD en sus representaciones literarias y cinematográficas en articulación con una etnografía sobre las vecindades de un ex CCD en particular, intentará volver sobre esta pregunta de dos modos distintos pero articulados. Por un lado, repasando dos trabajos clásicos sobre derecho transicional y responsabilidad de dos autores de destacada participación en el Juicio a las Juntas (Nino, 1997; MalamudGoti, 2000). Por el otro, rastreando el modo en que aquellas responsabilidades y justicias aparecen en dos entrevistas realizadas a vecinas de un ex CCD en particular, la Seccional 1o de Santa Rosa-La Pampa, durante nuestro trabajo de campo. En esta dirección intentará orientarse este trabajo