49 research outputs found
Thermal instability of an expanding dusty plasma with equilibrium cooling
We present an analysis of radiation induced instabilities in an expanding
plasma with considerable presence of dust particles and equilibrium cooling. We
have shown that the equilibrium expansion and cooling destabilize the radiation
condensation modes and the presence of dust particles enhances this effect. We
have examined our results in the context of ionized, dusty-plasma environments
such as those found in planetary nebulae (PNe). We show that due to the
non-static equilibrium and finite equilibrium cooling, small-scale localized
structures formed out of thermal instability, become transient, which agrees
with the observational results. The dust-charge fluctuation is found to heavily
suppress these instabilities, though in view of non-availability of convincing
experimental data, a definitive conclusion could not be made.Comment: 23 pages, 14 figure
Comparação de sistemas de marcadores moleculares para distinção de citoplasma normal (N) e macho-estéril (S) em cebola.
Resumo expandido
Análise via PCR de germoplasma de cebola empregando marcadores de moleculares derivados de genes análogos de resistência a doenças.
Suplemento. Resumo 532. Trabalho apresentado no 47. Congresso Brasileiro de Olericultura, 4. Simpósio Brasileiro sobre Cucurbitáceas, 2007. Porto Seguro
Residential mobility of middle-class and popular sectors: the city of Buenos Aires as an arrival destination
El artículo reflexiona acerca de los patrones de movilidad residencial de individuos y hogares de sectores populares y medios que residen en dos zonas de la Ciudad de Buenos Aires configuradas en torno a patrones disimiles de segregación. La movilidad residencial es un lente privilegiado para evidenciar de qué modo la experiencia de la clase es producida y reproducida en los modos de habitar. Mediante un abordaje cualitativo y biográfico hemos analizado las especificidades que presentan las movilidades residenciales de los diferentes sectores sociales. Se identifican patrones en tres dimensiones de la movilidad residencial: su espacialidad, los arreglos residenciales que los hogares despliegan y las motivaciones que guían sus desplazamientos. Los hallazgos presentados dan cuenta de los efectos que produce la posición en la estructura social sobre la movilidad residencial, así como su interacción con la propia estructuración del espacio.The article reconstructs residential mobility patterns of individuals and households from popular and middle-class sectors residing in two areas of the city of Buenos Aires, configured around dissimilar segregation patterns. Residential mobility is a powerful lens to show how the social class experience is produced and reproduced in modes of dwelling. Through a qualitative and biographical approach, we analyzed the specificities presented by residential mobilities of different social sectors. We identified patterns in the three dimensions of residential mobility: spatiality, the residential arrangements that households employ, and the motivations that guide their movements. The findings show the effects that the position in the social structure has on residential mobility, as well as its interaction with the spatial structure itself.publishedVersionFil: Cosacov, Andrea. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Cosacov, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas; Argentina.Fil: Di Virgilio, María Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Gino Germani; Argentina.Fil: Najman, Mercedes. Universidad de Buenos Aires. Facultad de Ciencias Sociales; Argentina.Fil: Di Virgilio, María Mercedes. Universidad de Buenos Aires. Facultad de Ciencias Sociales; Argentina.Fil: Najman, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Gino Germani; Argentina
Estimativa da diversidade genética de germosplasma de cebola via descritores morfológicos, agronômicos e bioquímicos.
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Previous issue date: 2008-04-16200
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Isomeric olefin tetracarbonyl complexes of tungsten(I): an infrared spectroelectrochemical study at low temperatures
In situ electrolysis within an optically transparent thin-layer electrochemical (OTTLE) cell was applied at 293-243 K in combination with FTIR spectroscopy to monitor spectral changes in the carbonyl stretching region accompanying oxidation of four tetracarbonyl olefin complexes of tungsten(0), viz., trans-[W(CO)(4)(eta(2)-ethene)(2)], trans-[W(CO)(4)(eta(2)-norbornene)(2)], [W(CO)(4)(eta(4)-cycloocta-1,5-diene)], and [W(CO)(4)(eta(4)-norbornadiene)]. In all cases, the one-electron-oxidized radical cations (17-electron complexes) have been identified by their characteristic nu(CO) patterns. For the bidentate diene ligands, the cis stereochemistry is essentially fixed in both the 18- and 17-electron complexes. The radical cation of the trans-bis(ethene) complex was observed only at 243 K, while at room temperature it isomerized rapidly to the corresponding cis-isomer. The thermal stability of the three studied radical cations in the cis configuration correlates with the relative strength of the W-CO bonds in the positions trans to the olefin ligand, which are more affected by the oxidation than the axial W-CO bonds. For the bulky norbornene ligands, their trans configuration in the bis(norbornene) complex remains preserved after the oxidation in the whole temperature range studied. The limited thermal stability of the radical cations of the trans-bis(alkene) complexes is ascribed to dissociation of the alkene ligands. The spectroelectrochemical results are in very good agreement with data obtained earlier by DFT (B3LYP) calculations