Diseño y desarrollo de un equipo de caracterización de ISFET para la medida de analitos iónicos

En este proyecto se desarrolla una unidad de medida para investigar la cuantificación de la concentración de analitos iónicos en análisis clínico mediante sensores ISFET. Para su desarrollo se precisa de un elemento que simule el comportamiento de un ISFET por lo que también se desarrolla un simulador de ISFET. Para realizar la unidad de medida se diseñan unos circuitos SMU que permiten polarizar en tensión y medir la corriente de cada terminal de un ISFET y del electrodo de referencia que actúa de puerta. El simulador se realiza con un MOSFET de la misma geometría que el ISFET y dos generadores de tensión programables. Desarrollados y validados los circuitos correspondientes, obtenemos unos excelentes resultados en el simulador que se revela de gran utilidad para la puesta en marcha de la unidad de medida, la cual ofrece unos resultados bastante buenos, si bien se aprecian ciertas corrientes de fuga que no permiten alcanzar toda la exactitud que se pretendía. Ello es debido a los circuitos impresos que deberán ser mejorados hasta conseguir la exactitud deseada. Sin embargo pueden darse por válidos los circuitos de medida diseñados.

Reactive Nitrogen and Oxygen Intermediates in Patients with Cutaneous Leishmaniasis

The metabolisms of reactive nitrogen and oxygen intermediates (RNI and ROI) in patients with cutaneous leishmaniasis (CL) were investigated and compared with those of healthy subjects. To determine RNI metabolism, nitrite plus nitrate concentrations were measured spectrophotometrically. Nitrite concentration in plasma was determined directly by the Griess method. Nitrate levels in plasma were measured after reduction into nitrite by using copper-cadmium-zinc. ROI metabolism was evaluated by measuring erythrocyte superoxide dismutase, catalase and glutathione peroxidase activities. Plasma nitrite plus nitrate levels and erythrocyte superoxide dismutase activity were higher in the patient group than healthy subjects (p<0.01). In contrast, erythrocyte catalase and glutathione peroxidase activities were lower (p<0.05, p<0.01, respectively). ROI metabolism was altered in relation to hydrogen peroxide elevation in patients with CL. These alterations in ROI enable nitric oxide (NO) to amplify its leishmanicidal effect. The determination of ROI and RNI in patients with CL may be a useful tool to evaluate effector mechanisms of NO and clinical manifestations.

Aspectos metabólicos y multivitamínicos del maíz

La deficiencia de vitamina A causa 2.2 millones de muertes al año. Por tanto, investigadores intentan elevar el contenido de β-caroteno y otros carotenoides en cereales mediante la ingeniería genética. Mi trabajo consistió en analizar carotenoides en maíz y callos de arroz transgénico con el fin de indentificar y cuantificar estos pigmentos y además analizar la ruta metabólica de los mismos. Por tal motivo, desarrollaré una técnica analítica por HPLC y UHPLC que me permitió separar la mezcla de carotenoides. Estas moléculas se detectaton utilizando un detector de arreglo de diodos y masas. Con éste último se probaron distintas técnicas de ionización (ESI, APCI y APPI) para encontrar la mejor técnica que ionizara carotenos y xantófilas. Además se hallaron transiciones para identificar a cada uno de los carotenoides. Para mostrar la confiabilidad del método analítico, realicé la validación del mismo y determiné factores importantes que influyen en el análisis de carotenoides, como por ejemplo, su estabilidad química. Para analizar la ruta metabólica de los carotenoides, se realizaron distintos experimentos, entre ellos, introducir distintas combinaciones de genes en el maíz y arroz que permitieran entender cuáles eran las enzimas importantes que permitían la acumulación de carotenoides. También se analizó la biosíntesis de carotenoides a distintas etapas del desarrollo de la semilla de maíz, desde los 15 días después de la polinización (DAP) hasta los 60 DAP y su estabilidad química a lo largo de todo este período. Finalmente, se profundizó en la identificación de nuevos carotenoides encontrados en las muestras, como los oxo-carotenoides (utilizados en la industria como colorantes). Para llevar acabo su identificación, se realizaron pruebas químicas, se determinaron sus espectros visibles y sus fragmentos por masas.   

Echolocation calls of the bats of Trinidad, West Indies: is guild membership reflected in echolocation signal design?

Time-expanded echolocation calls were recorded from 29 species of Neotropical bats in lowland moist tropical forest in Trinidad, West Indies with three aims (I) to describe the echolocation calls of the members of a diverse Neotropical bat community, especially members of the family Phyllostomidae, whose calls are not well documented (2) to investigate whether multivariate analysis of calls allows species and foraging guilds to be identified and (3) to evaluate the use of bat detectors in surveying the phyllostomids of Neotropical forests. The calls of 12 species of the family Phyllostomidae are described here for the first time and a total of 29 species, belonging to five families (Emballonuridae, Mormoopidae, Phyllostomidae, Molossidae and Vespertilionidae) were recorded Quadratic discriminant function analysis (DFA) was used to obtain classification rates for each one of 11 individual species and for six guilds (based on diet, foraging mode and habitat) comprising 26 species Overall classification rates were low compared to similar studies conducted in the Palaeotropics We suggest that this may be due to a combination of ecological plasticity for certain species and a loose relationship between echolocation call shape, fine-grained resource partitioning and resource acquisition in phyllostomids

High frequency of skin reactions in patients with leishmaniasis treated with meglumine antimoniate contaminated with heavy metals: a comparative approach using historical controls

We analyzed data from historical controls treated with meglumine antimoniate to compare the frequency of adverse events observed in patients with cutaneous leishmaniasis treated with the same dose of meglumine antimoniate contaminated with heavy metals in an endemic area of the State of Bahia, Brazil. Group A patients were treated in 2000 with the drug produced by Eurofarma Laboratórios Ltda., São Paulo, Brazil (lot A) and group B patients were treated in 1996 with the reference drug produced by Rhodia Farma Ltda., São Paulo, Brazil (lot B). We observed an unusual higher frequency of skin reactions in group A patients. However, all type of adverse events observed in group A were also observed in group B. The physico-chemical analysis of these lots revealed that lot A had lower pH and higher concentration of total and trivalent antimony, lead, cadmium, and arsenic. Our findings suggest that the skin reactions could be attributed to heavy metal contamination of lot A.

Ultra-high pressure liquid chromatography-mass spectrometry for plant metabolomics: a systematic comparison of high-resolution quadrupole-time-of-flight and single stage Orbitrap mass spectrometers.

The response of Arabidopsis to stress caused by mechanical wounding was chosen as a model to compare the performances of high resolution quadrupole-time-of-flight (Q-TOF) and single stage Orbitrap (Exactive Plus) mass spectrometers in untargeted metabolomics. Both instruments were coupled to ultra-high pressure liquid chromatography (UHPLC) systems set under identical conditions. The experiment was divided in two steps: the first analyses involved sixteen unwounded plants, half of which were spiked with pure standards that are not present in Arabidopsis. The second analyses compared the metabolomes of mechanically wounded plants to unwounded plants. Data from both systems were extracted using the same feature detection software and submitted to unsupervised and supervised multivariate analysis methods. Both mass spectrometers were compared in terms of number and identity of detected features, capacity to discriminate between samples, repeatability and sensitivity. Although analytical variability was lower for the UHPLC-Q-TOF, generally the results for the two detectors were quite similar, both of them proving to be highly efficient at detecting even subtle differences between plant groups. Overall, sensitivity was found to be comparable, although the Exactive Plus Orbitrap provided slightly lower detection limits for specific compounds. Finally, to evaluate the potential of the two mass spectrometers for the identification of unknown markers, mass and spectral accuracies were calculated on selected identified compounds. While both instruments showed excellent mass accuracy (<2.5ppm for all measured compounds), better spectral accuracy was recorded on the Q-TOF. Taken together, our results demonstrate that comparable performances can be obtained at acquisition frequencies compatible with UHPLC on Q-TOF and Exactive Plus MS, which may thus be equivalently used for plant metabolomics.

Elaboració d'un protocol basat en XML per a una xarxa de sensors

La progressiva reducció de dimensió i cost en els dispositius electrònics, la dràstica retallada de consum elèctric i la independència de què això els dota han fet créixer en els últims temps l'interès de les comunitats científiques i tecnològiques per les xarxes sense fils de petits dispositius. Per altra banda, l'XML (eXtensible Markup Language) és un metallenguatge extensible que ha esdevingut un estàndard per a l'intercanvi d'informació estructurada entre diferents plataformes. L'objectiu d'aquest treball és explorar les possibilitats que pot oferir la introducció de l'XML en les xarxes de sensors amb l'elaboració d'un protocol de comunicació basat en aquest llenguatge i demostrar la transparència en el canvi de plataforma. Per fer-ho, es disposa de dos dispositius amb capacitat de comunicació sense fils equipats amb detectors de temperatura, lluminositat, efecte Hall i nivell de càrrega de la bateria. El projecte constarà de dues parts: una, més extensa, dedicada al desenvolupament del programari per a aquests dispositius, encarregat de obtenir les lectures dels diferents sensors i emetre-les per la xarxa utilitzant el llenguatge XML, i una altra, per recollir aquesta informació present a la xarxa, interpretar-la, salvar-la en una base de dades i exposar-la al món en una plana web. El programari dels dispositius sensors s'escriurà en llenguatge nesC dins el sistema tinyOS que és el sistema operatiu que equipen. La part d'explotació de les dades es desenvoluparà sota la plataforma .NET de Microsoft.

Major influencing factors of indoor radon concentrations in Switzerland.

PURPOSE: In Switzerland, nationwide large-scale radon surveys have been conducted since the early 1980s to establish the distribution of indoor radon concentrations (IRC). The aim of this work was to study the factors influencing IRC in Switzerland using univariate analyses that take into account biases caused by spatial irregularities of sampling. METHODS: About 212,000 IRC measurements carried out in more than 136,000 dwellings were available for this study. A probability map to assess risk of exceeding an IRC of 300 Bq/m(3) was produced using basic geostatistical techniques. Univariate analyses of IRC for different variables, namely the type of radon detector, various building characteristics such as foundation type, year of construction and building type, as well as the altitude, the average outdoor temperature during measurement and the lithology, were performed comparing 95% confidence intervals among classes of each variable. Furthermore, a map showing the spatial aggregation of the number of measurements was generated for each class of variable in order to assess biases due to spatially irregular sampling. RESULTS: IRC measurements carried out with electret detectors were 35% higher than measurements performed with track detectors. Regarding building characteristics, the IRC of apartments are significantly lower than individual houses. Furthermore, buildings with concrete foundations have the lowest IRC. A significant decrease in IRC was found in buildings constructed after 1900 and again after 1970. Moreover, IRC decreases at higher outdoor temperatures. There is also a tendency to have higher IRC with altitude. Regarding lithology, carbonate rock in the Jura Mountains produces significantly higher IRC, almost by a factor of 2, than carbonate rock in the Alps. Sedimentary rock and sediment produce the lowest IRC while carbonate rock from the Jura Mountains and igneous rock produce the highest IRC. Potential biases due to spatially unbalanced sampling of measurements were identified for several influencing factors. CONCLUSIONS: Significant associations were found between IRC and all variables under study. However, we showed that the spatial distribution of samples strongly affected the relevance of those associations. Therefore, future methods to estimate local radon hazards should take the multidimensionality of the process of IRC into account.

Probabilistic sonar scan matching for an AUV

This paper proposes MSISpIC, a probabilistic sonar scan matching algorithm for the localization of an autonomous underwater vehicle (AUV). The technique uses range scans gathered with a Mechanical Scanning Imaging Sonar (MSIS), the robot displacement estimated through dead-reckoning using a Doppler velocity log (DVL) and a motion reference unit (MRU). The proposed method is an extension of the pIC algorithm. An extended Kalman filter (EKF) is used to estimate the robot-path during the scan in order to reference all the range and bearing measurements as well as their uncertainty to a scan fixed frame before registering. The major contribution consists of experimentally proving that probabilistic sonar scan matching techniques have the potential to improve the DVL-based navigation. The algorithm has been tested on an AUV guided along a 600 m path within an abandoned marina underwater environment with satisfactory results

International exercise on 124Sb activity measurements.

An international exercise, registered as EUROMET project no. 907, was launched to measure both the activity of a solution of (124)Sb and the photon emission intensities of its decay. The same solution was sent by LNE-LNHB to eight participating laboratories. In order to identify possible biases, the participants were asked to use all possible activity measurement methods available in their laboratory and then to determine their reference value for comparison. Thus, measurement results from 4pibeta-gamma coincidence/anti-coincidence counting, CIEMAT/NIST liquid-scintillation counting, 4pigamma counting with well-type ionization chambers and well-type crystal detectors were given. The results are compared and show a maximum discrepancy of about 1.6%: possible explanations are proposed.

A review of sensor fusion techniques for underwater vehicle navigation

This work provides a general description of the multi sensor data fusion concept, along with a new classification of currently used sensor fusion techniques for unmanned underwater vehicles (UUV). Unlike previous proposals that focus the classification on the sensors involved in the fusion, we propose a synthetic approach that is focused on the techniques involved in the fusion and their applications in UUV navigation. We believe that our approach is better oriented towards the development of sensor fusion systems, since a sensor fusion architecture should be first of all focused on its goals and then on the fused sensors

Accuracy estimation of a new omnidirectional 3D vision sensor

We present a computer vision system that associates omnidirectional vision with structured light with the aim of obtaining depth information for a 360 degrees field of view. The approach proposed in this article combines an omnidirectional camera with a panoramic laser projector. The article shows how the sensor is modelled and its accuracy is proved by means of experimental results. The proposed sensor provides useful information for robot navigation applications, pipe inspection, 3D scene modelling etc

Overview of coded light projection techniques for automatic 3D profiling

Obtaining automatic 3D profile of objects is one of the most important issues in computer vision. With this information, a large number of applications become feasible: from visual inspection of industrial parts to 3D reconstruction of the environment for mobile robots. In order to achieve 3D data, range finders can be used. Coded structured light approach is one of the most widely used techniques to retrieve 3D information of an unknown surface. An overview of the existing techniques as well as a new classification of patterns for structured light sensors is presented. This kind of systems belong to the group of active triangulation method, which are based on projecting a light pattern and imaging the illuminated scene from one or more points of view. Since the patterns are coded, correspondences between points of the image(s) and points of the projected pattern can be easily found. Once correspondences are found, a classical triangulation strategy between camera(s) and projector device leads to the reconstruction of the surface. Advantages and constraints of the different patterns are discussed

Neptune: a hil simulator for multiple UUVs

This paper overviews the field of graphical simulators used for AUV development, presents the taxonomy of these applications and proposes a classification. It also presents Neptune, a multivehicle, real-time, graphical simulator based on OpenGL that allows hardware in the loop simulations

GNSS signal detection based on first-order absolute statistics

Aquest projecte es centra principalment en el detector no coherent d’un GPS. Per tal de caracteritzar el procés de detecció d’un receptor, es necessita conèixer l’estadística implicada. Pel cas dels detectors no coherents convencionals, l’estadística de segon ordre intervé plenament. Les prestacions que ens dóna l’estadística de segon ordre, plasmada en la ROC, són prou bons tot i que en diferents situacions poden no ser els millors. Aquest projecte intenta reproduir el procés de detecció mitjançant l’estadística de primer ordre com a alternativa a la ja coneguda i implementada estadística de segon ordre. Per tal d’aconseguir-ho, s’usen expressions basades en el Teorema Central del Límit i de les sèries Edgeworth com a bones aproximacions. Finalment, tant l’estadística convencional com l’estadística proposada són comparades, en termes de la ROC, per tal de determinar quin detector no coherent ofereix millor prestacions en cada situació.