An evaluation of cognitive deficits in a rat-model of Huntington's disease

The purpose of this thesis was to develop methodology by which treatments for the cognitive impairments in Huntington’s disease (HD) could be tested. As such, the thesis focused mainly on evaluating rats with quinolinic acid (QA) lesions of the striatum, as this manipulation mimics some aspects of the neural damage in Huntington’s disease, to try to identify cognitive deficits of HD resulting from cell loss in the striatum. In the first part (Chapters 3-5), the role of the striatum in implicit memory was investigated. Chapter 3 compared the performance of rats and humans on a reaction time task that evaluated implicit memory by presenting visual stimuli with differing probabilities which change over time. Although rats made higher percentage of incorrect responses and late errors, both groups showed a similar pattern of reaction times. Chapter 4 investigated whether implicit memory (the computation of probabilities to predict the location of a stimulus) was affected by selective blockade of dopaminergic transmission at the D1 or D2 receptors by SCH-23390 and raclopride, respectively. Reaction times were slower with SCH-23390 and raclopride, but only SCH-23390 reduced errors to the least probable target location. Chapter 5 used the same task to evaluate implicit memory in rats with QA lesions of the dorsomedial striatum (DMS). Implicit memory was not affected by lesions of the DMS, which suggested that once a task that requires implicit memory has been learned, the DMS was not involved in sustaining the performance of the task. The second part of this thesis (Chapter 6), explored the contribution of the DMS in habit formation. DMS lesioned rats did not show habitual responding, and were not impaired in learning a new goal-directed behaviour. The third part (Chapters 7 and 8), investigated the role of the dorsal striatum in reversal learning, attentional set-formation, and set-shifting. Dorsal striatum lesioned rats were not impaired in reversal learning, but had a diminished shift-cost, which suggested that dorsal striatum lesions disrupted the formation of attentional sets. These results showed that although QA lesions of the dorsal striatum mimic some aspects of the neural damage in HD, they did not result in the same cognitive deficits observed in patients with HD, at least using the tasks presented in this thesis. However, other animal models of HD could be evaluated using the different tasks presented in this thesis to continue the search of a reliable animal model of HD in which treatments for the disease could be evaluated

A low cost 3D vision system for positioning welding mobile robots using a FPGA prototyping system

The aim of this work is to explore some solutions for artificial vision systems applied to welding autonomous robots. We take advantage from the UNSHADES-1 system, developed in Filiation (blind for evaluation). This system can be used for building a powerful 3D vision system. The system concentrates and process the three images in parallel, producing an accurate value of the position, that can be improved if the relative position of the cameras are well defined

La importancia de los trabajos de campo en la confección del modelo del terreno para aplicaciones en ecología

The main aim of this paper is to highlight the extraordinary importance of field surveying for carrying out certain ecological models in which habitats of vegetal communities are conditioned by land elevation. An illustrated case study in the wetlands of Doñana National Park shows the key role of Field Inspections, particularly since morphology (altitude attribute) is one of the first factors that condition the superficial expansion of the main vegetal perennial communities within the wetland system.Se pretende demostrar la extraordinaria incidencia que tienen los trabajos de campo en la confección de determinados modelos ecológicos, en los que el relieve del terreno condiciona el hábitat de sus principales comunidades vegetales. Se ilustra esta hipótesis con un ejemplo extraído de la marisma del Parque Nacional de Doñana, donde su morfología es uno de los factores principales que configura la fisonomía del paisaje vegetal, al condicionar la expansión de las principales agrupaciones vegetales perennes del sistema marismeño

Solar-like oscillations in cluster stars

We present a brief overview of the history of attempts to obtain a clear detection of solar-like oscillations in cluster stars, and discuss the results on the first clear detection, which was made by the Kepler Asteroseismic Science Consortium (KASC) Working Group 2.Comment: 4 pages, 7 figures, accepted by Astronomische Nachrichte

Aspectos florísticos de Lacanhá Chansayab, Selva Lacandona, Chiapas

A systematic sampling of the flora was carried out between 1993 and 1999 in several evergreen tropical rainforest stands, “acahuales” (local name for old agricultural fields) of various ages and agricultural fields belonging to the Lacanhá Chansayab community, located at the Lacandonian tropical rainforest. Collected individuals were identified and processed as herbarium specimens, including information on life form, phenology and status of conservation. Four hundred and eighty five vascular plant species were recorded, corresponding to 355 genera from 104 families, which represent 11.23% of all species estimated for the area. Fabaceae, Asteraceae and Rubiaceae were the best represented families, as well as the genera Piper, Eupatorium, Encyclia, Chamaedorea and Solanum.Entre 1993 y 1999 se realizaron herborizaciones sistemáticas en rodales de selva alta perennifolia, acahuales de diferentes edades y milpas pertenecientes a la comunidad de Lacanhá Chansayab, en la Selva Lacandona. Los especímenes recolectados se identificaron y procesaron como ejemplares de herbario, acompañados de información sobre su forma de vida, fenología y estado de conservación. Se registraron 485 especies de plantas vasculares, pertenecientes a 355 géneros de 104 familias, las cuales representan 11.23% del total de especies estimado para la zona. Fabaceae, Asteraceae y Rubiaceae fueron las familias mejor representadas, así como los géneros Piper, Eupatorium, Encyclia, Chamaedorea y Solanum

Testing the Asteroseismic Mass Scale Using Metal-Poor Stars Characterized with APOGEE and Kepler

Fundamental stellar properties, such as mass, radius, and age, can be inferred using asteroseismology. Cool stars with convective envelopes have turbulent motions that can stochastically drive and damp pulsations. The properties of the oscillation frequency power spectrum can be tied to mass and radius through solar-scaled asteroseismic relations. Stellar properties derived using these scaling relations need verification over a range of metallicities. Because the age and mass of halo stars are well-constrained by astrophysical priors, they provide an independent, empirical check on asteroseismic mass estimates in the low-metallicity regime. We identify nine metal-poor red giants (including six stars that are kinematically associated with the halo) from a sample observed by both the Kepler space telescope and the Sloan Digital Sky Survey-III APOGEE spectroscopic survey. We compare masses inferred using asteroseismology to those expected for halo and thick-disk stars. Although our sample is small, standard scaling relations, combined with asteroseismic parameters from the APOKASC Catalog, produce masses that are systematically higher (=0.17+/-0.05 Msun) than astrophysical expectations. The magnitude of the mass discrepancy is reduced by known theoretical corrections to the measured large frequency separation scaling relationship. Using alternative methods for measuring asteroseismic parameters induces systematic shifts at the 0.04 Msun level. We also compare published asteroseismic analyses with scaling relationship masses to examine the impact of using the frequency of maximum power as a constraint. Upcoming APOKASC observations will provide a larger sample of ~100 metal-poor stars, important for detailed asteroseismic characterization of Galactic stellar populations.Comment: 4 figures; 1 table. Accepted to ApJ