DECISION TREE CLASSIFIERS FOR STAR/GALAXY SEPARATION

We study the star/galaxy classification efficiency of 13 different decision tree algorithms applied to photometric objects in the Sloan Digital Sky Survey Data Release Seven (SDSS-DR7). Each algorithm is defined by a set of parameters which, when varied, produce different final classification trees. We extensively explore the parameter space of each algorithm, using the set of 884,126 SDSS objects with spectroscopic data as the training set. The efficiency of star-galaxy separation is measured using the completeness function. We find that the Functional Tree algorithm (FT) yields the best results as measured by the mean completeness in two magnitude intervals: 14 <= r <= 21 (85.2%) and r >= 19 (82.1%). We compare the performance of the tree generated with the optimal FT configuration to the classifications provided by the SDSS parametric classifier, 2DPHOT, and Ball et al. We find that our FT classifier is comparable to or better in completeness over the full magnitude range 15 <= r <= 21, with much lower contamination than all but the Ball et al. classifier. At the faintest magnitudes (r > 19), our classifier is the only one that maintains high completeness (> 80%) while simultaneously achieving low contamination (similar to 2.5%). We also examine the SDSS parametric classifier (psfMag - modelMag) to see if the dividing line between stars and galaxies can be adjusted to improve the classifier. We find that currently stars in close pairs are often misclassified as galaxies, and suggest a new cut to improve the classifier. Finally, we apply our FT classifier to separate stars from galaxies in the full set of 69,545,326 SDSS photometric objects in the magnitude range 14 <= r <= 21.

A SON Enhanced Algorithm for Observed Time Differences Based Geolocation in Real 3G Networks

Conferência - 16th International Symposium on Wireless Personal Multimedia Communications (WPMC)- Jun 24-27, 2013

Laboratory directions in general biology / by Edwin G. Conklin.

Third Edition

Laboratory directions in general biology / by Edwin G. Conklin.

First Edition

Two different 3D biogeochemical models for the NW mediterranean sea: validation with Meris data and intercomparison

Report for the scientific sojourn carried out at the University of New South Wales from February to June the 2007. Two different biogeochemical models are coupled to a three dimensional configuration of the Princeton Ocean Model (POM) for the Northwestern Mediterranean Sea (Ahumada and Cruzado, 2007). The first biogeochemical model (BLANES) is the three-dimensional version of the model described by Bahamon and Cruzado (2003) and computes the nitrogen fluxes through six compartments using semi-empirical descriptions of biological processes. The second biogeochemical model (BIOMEC) is the biomechanical NPZD model described in Baird et al. (2004), which uses a combination of physiological and physical descriptions to quantify the rates of planktonic interactions. Physical descriptions include, for example, the diffusion of nutrients to phytoplankton cells and the encounter rate of predators and prey. The link between physical and biogeochemical processes in both models is expressed by the advection-diffusion of the non-conservative tracers. The similarities in the mathematical formulation of the biogeochemical processes in the two models are exploited to determine the parameter set for the biomechanical model that best fits the parameter set used in the first model. Three years of integration have been carried out for each model to reach the so called perpetual year run for biogeochemical conditions. Outputs from both models are averaged monthly and then compared to remote sensing images obtained from sensor MERIS for chlorophyll.

Matching and Sorting in a Global Economy

We develop a neoclassical trade model with heterogeneous factors of production. We consider a world with two factors, labor and .managers., each with a distribution of ability levels. Production combines a manager of some type with a group of workers. The output of a unit depends on the types of the two factors, with complementarity between them, while exhibiting diminishing returns to the number of workers. We examine the sorting of factors to sectors and the matching of factors within sectors, and we use the model to study the determinants of the trade pattern and the effects of trade on the wage and salary distributions. Finally, we extend the model to include search frictions and consider the distribution of employment rates.

Crazy ideas ?

Review of the book : "Nine crazy ideas in Science: a few might even be true", by R. Ehrlich, Princeton University Press, New-Jersey

Condiciones para una arquitectura radical

La investigación Condiciones para una arquitectura radical se ha desarrollado en el marco de la beca FI 2009-12; y también incluye una beca de movilidad BE-DGR 2009 por un período de seis meses de 2010 en Princeton University School of Architecture. Condiciones para una arquitectura radical tiene un objetivo general: trabajar las relaciones entre límite, experiencia y comunidad a partir de dos pilares: arte y tecnología. Son tres familias de conceptos y sus articulaciones complejas en el espacio común: para definir en última instancia, otros procesos posibles de gestión en la ciudad. La lucha ideológica está en pensar cual debería ser el futuro de las ciudades. El objetivo concreto de la tesis es la búsqueda de herramientas para abrir nuevos espacios en la ciudad donde materializar un cambio social y urbano. Para entender esta aproximación la investigación indaga en los momentos de acercamiento y simbiosis de la arquitectura a las tesis del arte y la tecnología: una mirada atenta a las condiciones de contexto. Se explora el cruce de algunas ideas emancipadoras que se formularon en diferentes momentos de la cultura - desde las vanguardias históricas hasta ahora- en los que se intuyó la importancia del sistema abierto -el paso del objeto al proceso- y su trasposición en arquitectura: una arquitectura y un urbanismo open source; son episodios en los que ha existido un cuestionamiento de las fronteras disciplinares y un interés por la apropiación convivencial de lo público. Algunas de aquellas ideas pueden repetirse en el contexto activo de unas nuevas condiciones.

Eight controversies

Review of the book: Eight preposterous propositions by Robert Ehrlich, Princeton University press, Princeton USA.