6,173 research outputs found
Ciudades y resiliencia : riesgo, vulnerabilidad y adaptación en América Latina
El propĂłsito de este texto es discutir el concepto de resiliencia y buscar su interĂ©s heurĂstico para los análisis de vulnerabilidad urbana. El tĂ©rmino resiliencia es omnipresente en la retĂłrica de las declaraciones internacionales, de las polĂticas pĂşblicas y en las reflexiones acadĂ©micas en el campo de los riesgos y desastres en ciudades. Se discute esta nociĂłn con el fin de entender sus raĂces y desvelar sus presupuestos ideolĂłgicos. Al mismo tiempo, el tĂ©rmino resiliencia presenta el interĂ©s de fomentar debates y cuestiones teĂłricas en el campo cientĂfico y en el sociopolĂtico de la formulaciĂłn de nuevas polĂticas pĂşblicas. Más allá de los enfoques focalizados sobre el fortalecimiento de las capacidades locales, los aportes heurĂsticos del concepto de resiliencia para los análisis de riesgos en el medio urbano provienen de sus fundamentos en la teorĂa de los sistemas complejos. AsĂ, 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
CaracterĂsticas agroclimáticas de la RegiĂłn Pampeana Argentina
p.41-64Se analizan con criterio agroclimático los principales aspectos de los regĂmenes tĂ©rmico e hĂdrico que en la Padrea Pampeana argentina afectan la producciĂłn agrĂcola y particularmente la de los cultivos anuales extensivos. La disponibilidad calĂłrica de ambas termi fases anuales se examinan mediante Ăndices agroclimáticos como: duraciĂłn del perĂodo libre de heladas, niveles tĂ©rmicos crĂticos, bioperĂodostĂ©rmicos, suma de temperaturas y condiciones de vernalizaciĂłn, mientras que la variaciĂłn en los niveles de humedad edáfica y las probabilidades de ocurrencia de excesos y deficiencias de agua se usan para caracterizar las condiciones hidrolĂłgicas. A travĂ©s de una cartaografĂa seleccionada se muestra la variaciĂłn de estos valores agroclimáticos discutiĂ©ndose su repercuciĂłn en los cultivos agrĂcolas
Fechas medias estimadas de primeras y Ăşltimas temperaturas mĂnimas perjudiciales para los cultivos en la Argentina
p.193-211Se presentan 14 cartas agroclimáticas de las fechas medias de primeras y Ăşltimas temperaturas de 3°, 0°, - 1°, - 2° , - 3°, - 4° y -5° C para el territorio de la Argentina. Los niveles considerados son temperaturas crĂticas para el crecimiento de distintos cultivos agrĂcolas en las diferentes etapas de su desarrollo. Para confeccionar las cartas se utilizan valores estimados mediante la aplicaciĂłn del m Ă©todo gráfico de aproximaciĂłn propuesto por Papadakis (1951) basado en las tem peraturas mĂnimas mensuales medias. La eficiencia del m Ă©todo se discute previamente en su aplicaciĂłn a dos áreas geográfica y climáticamente diferentes: la pradera pampeana argentina y la regiĂłn italiana del valle del Po. Se analizan las posibles causas de los desajustes encontrados con el propĂłsito de formular una metodologĂa de correcciĂłn 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
Limited results of group self-management education for rheumatoid arthritis patients and their partners: explanations from the patient perspective
This study aimed to identify the reasons for limited results of group self-management for RA patients and their partners from the patient perspective. Semi-structured interviews with ten male and ten female patients who had participated in group self-management with or without their partner were content analyzed with respect to motivation to participate and the effects of the program on them. The limited effects of the self-management program appear to be linked with low motivation to participate and to change health behavior. The data show that a decline in health and also stressful life events might be associated with the disappointing effects of the program. Three strategies were proposed for improving the program’s effects: (a) provide information about the program in advance to ensure that patients have appropriate expectations. (b) Enhance intrinsic motivation to change health behavior by counseling techniques. (c) Tailoring with respect to motivation and current concerns could help to form more homogeneous groups or could be the basis for a tailored online intervention
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