Lo imaginario espacial y la geografía. En defensa de la geografía de las representaciones.

Sin resume

La différenciation de l’espace urbain de Québec : une application de l’analyse discriminante en géographie urbaine

Puisqu'il n'est pas de connaissance géographique sans différenciation des paysages, la géographie quantitative ne peut se contenter des seules méthodes factorielles. Avec l'analyse discriminante, les poids locaux ne constituent plus l'étape finale, mais le point de départ de l'analyse spatiale. Ainsi procédons-nous à l'étude des espaces socio-économiques et familiaux pour la région métropolitaine de Québec. Loin d'être conforme aux modèles nord-américains, cette ville présente un double aspect: l'un culturel et symbolique, favorisant la conservation de plusieurs secteurs centraux, l'autre économique, entraînant invasions et successions dans les aires périphériques. Même si l'analyse discriminante pose plusieurs problèmes méthodologiques, elle offre au géographe un instrument qui peut servir de support logique pour bâtir une théorie de la ville.Since geography implies the study of space and its influence on human behavior, quantitative geography must encompass more than standard factorial methods. The interpretation of factor loadings and the subsequent description of factor score patterns should thus not constitute the final stage of any spatial analysis but rather the starting point. We study the socio-economic and family « spaces » of the Québec city urban region. We find that the Québec model tends to differ from the classic North American model; symbolic and cultural factors make for a much more coherent and dense centre city while economic factors, as elsewhere on the continent, result in a pattern of concentric zones around the C.B.D. Even though the use of discriminant analysis poses certain methodological problems, we nonetheless found it to be a useful technique for understanding urban social space

Clustering with shallow trees

We propose a new method for hierarchical clustering based on the optimisation of a cost function over trees of limited depth, and we derive a message--passing method that allows to solve it efficiently. The method and algorithm can be interpreted as a natural interpolation between two well-known approaches, namely single linkage and the recently presented Affinity Propagation. We analyze with this general scheme three biological/medical structured datasets (human population based on genetic information, proteins based on sequences and verbal autopsies) and show that the interpolation technique provides new insight.Comment: 11 pages, 7 figure

Cosmological evolution of scalar fields and gravitino dark matter in gauge mediation at low reheating temperatures

We consider the dynamics of the supersymmetry-breaking scalar field and the production of dark matter gravitinos via its decay in a gauge-mediated supersymmetry breaking model with metastable vacuum. We find that the scalar field amplitude and gravitino density are extremely sensitive to the parameters of the hidden sector. For the case of an O'Raifeartaigh sector, we show that the observed dark matter density can be explained by gravitinos even for low reheating temperatures T_{R} < 10 GeV. Such low reheating temperatures may be implied by detection of the NLSP at the LHC if its thermal freeze-out density is in conflict with BBN.Comment: 11 pages RevTex. Extended discussion and minor corrections, conclusions unaltered. Version to be published in JCA