Ciudades y resiliencia : riesgo, vulnerabilidad y adaptación en América Latina

El propósito de este texto es discutir el concepto de resiliencia y buscar su interés heurístico para los análisis de vulnerabilidad urbana. El término resiliencia es omnipresente en la retórica de las declaraciones internacionales, de las políticas públicas y en las reflexiones académicas en el campo de los riesgos y desastres en ciudades. Se discute esta noción con el fin de entender sus raíces y desvelar sus presupuestos ideológicos. Al mismo tiempo, el término resiliencia presenta el interés de fomentar debates y cuestiones teóricas en el campo científico y en el sociopolítico de la formulación de nuevas políticas públicas. Más allá de los enfoques focalizados sobre el fortalecimiento de las capacidades locales, los aportes heurísticos del concepto de resiliencia para los análisis de riesgos en el medio urbano provienen de sus fundamentos en la teoría de los sistemas complejos. Así, se resaltan nuevos enfoques y soportes conceptuales que permiten entender mejor la vulnerabilidad de las grandes aglomeraciones urbanas

BLAST Autonomous Daytime Star Cameras

We have developed two redundant daytime star cameras to provide the fine pointing solution for the balloon-borne submillimeter telescope, BLAST. The cameras are capable of providing a reconstructed pointing solution with an absolute accuracy < 5 arcseconds. They are sensitive to stars down to magnitudes ~ 9 in daytime float conditions. Each camera combines a 1 megapixel CCD with a 200 mm f/2 lens to image a 2 degree x 2.5 degree field of the sky. The instruments are autonomous. An internal computer controls the temperature, adjusts the focus, and determines a real-time pointing solution at 1 Hz. The mechanical details and flight performance of these instruments are presented.Comment: 8 pages, 6 figures, 1 table. To be published in conference proceedings for the "Ground-based and Airborne Instrumentation for Astronomy" part of the SPIE Astronomical Telescopes and Instrumentation Symposium that will be held 24-31 May 2006 in Orlando, F

A practical model of convective dynamics for stellar evolution calculations

Turbulent motions in the interior of a star play an important role in its evolution, since they transport chemical species, thermal energy and angular momentum. Our overall goal is to construct a practical turbulent closure model for convective transport that can be used in a multi-dimensional stellar evolution calculation including the effects of rotation, shear and magnetic fields. Here, we focus on the first step of this task: capturing the well-known transition from radiative heat transport to turbulent convection with and without rotation, as well as the asymptotic relationship between turbulent and radiative transport in the limit of large Rayleigh number. We extend the closure model developed by Ogilvie (2003) and Garaud and Ogilvie (2005) to include heat transport and compare it with experimental results of Rayleigh-Benard convection.Comment: Conference proceeding for poster at conference "Unsolved problems in Stellar Physics

High frequency GaAs nano-optomechanical disk resonator

Optomechanical coupling between a mechanical oscillator and light trapped in a cavity increases when the coupling takes place in a reduced volume. Here we demonstrate a GaAs semiconductor optomechanical disk system where both optical and mechanical energy can be confined in a sub-micron scale interaction volume. We observe giant optomechanical coupling rate up to 100 GHz/nm involving picogram mass mechanical modes with frequency between 100 MHz and 1 GHz. The mechanical modes are singled-out measuring their dispersion as a function of disk geometry. Their Brownian motion is optically resolved with a sensitivity of 10^(-17)m/sqrt(Hz) at room temperature and pressure, approaching the quantum limit imprecision.Comment: 7 pages, 3 figure

Evolutionary neurocontrol: A novel method for low-thrust gravity-assist trajectory optimization

This article discusses evolutionary neurocontrol, a novel method for low-thrust gravity-assist trajectory optimization

Características agroclimáticas de la Región Pampeana Argentina

p.41-64Se analizan con criterio agroclimático los principales aspectos de los regímenes térmico e hídrico que en la Padrea Pampeana argentina afectan la producción agrícola y particularmente la de los cultivos anuales extensivos. La disponibilidad calórica de ambas termi fases anuales se examinan mediante índices agroclimáticos como: duración del período libre de heladas, niveles térmicos críticos, bioperíodostérmicos, suma de temperaturas y condiciones de vernalización, mientras que la variación en los niveles de humedad edáfica y las probabilidades de ocurrencia de excesos y deficiencias de agua se usan para caracterizar las condiciones hidrológicas. A través de una cartaografía seleccionada se muestra la variación de estos valores agroclimáticos discutiéndose su repercución en los cultivos agrícolas

Fechas medias estimadas de primeras y últimas temperaturas mínimas perjudiciales para los cultivos en la Argentina

p.193-211Se presentan 14 cartas agroclimáticas de las fechas medias de primeras y últimas temperaturas de 3°, 0°, - 1°, - 2° , - 3°, - 4° y -5° C para el territorio de la Argentina. Los niveles considerados son temperaturas críticas para el crecimiento de distintos cultivos agrícolas en las diferentes etapas de su desarrollo. Para confeccionar las cartas se utilizan valores estimados mediante la aplicación del m étodo gráfico de aproximación propuesto por Papadakis (1951) basado en las tem peraturas mínimas mensuales medias. La eficiencia del m étodo se discute previamente en su aplicación a dos áreas geográfica y climáticamente diferentes: la pradera pampeana argentina y la región italiana del valle del Po. Se analizan las posibles causas de los desajustes encontrados con el propósito de formular una metodología de corrección y ajuste

Does Land Tenure Insecurity Drive Deforestation in the Brazilian Amazon?

The purpose of this paper is to highlight the detrimental impact of land tenure insecurity on deforestation in the Brazilian Amazon. It is related to recent controversies about the detrimental impact of land laws on deforestation, which seem to legitimize land encroachments. The latter is mainly the result of land tenure insecurity which is a key characteristic of this region and results from a long history of interactions between rural social unrest and land reforms or land laws. A simple model is developed where strategic interactions between farmers lead to excessive deforestation. One of the empirical implications of the model is a positive relationship between land tenure insecurity and the extent of deforestation. The latter is tested on data from a panel of Brazilian Amazon municipalities. The negative effect of land tenure insecurity proxied by the number of squatters on deforestation is not rejected when estimations are controlled for the possible endogeneity of squatters. One of the main policy implications is that ex post legalizations of settlements must be accompanied by the enforcement of environmental obligations.deforestation, land tenure insecurity, squatters, Panel Data Analysis, Brazil

Method for providing a polarization filter for processing synthetic aperture radar image data

A polarization filter can maximize the signal-to-noise ratio of a polarimetric SAR and help discriminate between targets or enhance image features, e.g., enhance contract between different types of target. The method disclosed is based on the Stokes matrix/Stokes vector representation, so the targets of interest can be extended targets, and the method can also be applied to the case of bistatic polarimetric radars