Análisis de diversidad de la familia Poaceae en la región austral de America del Sur

337-351Analysis of Poaceae biodiversity in austral South America. The Poaceae is one of the best represented families in austral South America with a total of 206 genera comprising 1523 species arranged in 10 different subfamilies. Here we analyzed the distribution of these taxa in Argentina, southern Brazil (Paraná, Rio Grande do Sul and Santa Catarina), Chile, Paraguay, and Uruguay; we discuss the species richness of the different subfamilies, tribes and genera, its distribution, endemics, annual and perennial species as well as Kranz and non Kranz taxa, its geographical distribution in relation to temperature and rainfall, disjunct genera, and proportion of taxa in relation to the different ecoregions in the area

Macro-Climatic Distribution Limits Show Both Niche Expansion and Niche Specialization among C4 Panicoids

Grasses are ancestrally tropical understory species whose current dominance in warm open habitats is linked to the evolution of C4 photosynthesis. C4 grasses maintain high rates of photosynthesis in warm and water stressed environments, and the syndrome is considered to induce niche shifts into these habitats while adaptation to cold ones may be compromised. Global biogeographic analyses of C4 grasses have, however, concentrated on diversity patterns, while paying little attention to distributional limits. Using phylogenetic contrast analyses, we compared macro-climatic distribution limits among ~1300 grasses from the subfamily Panicoideae, which includes 4/5 of the known photosynthetic transitions in grasses. We explored whether evolution of C4 photosynthesis correlates with niche expansions, niche changes, or stasis at subfamily level and within the two tribes Paniceae and Paspaleae. We compared the climatic extremes of growing season temperatures, aridity, and mean temperatures of the coldest months. We found support for all the known biogeographic distribution patterns of C4 species, these patterns were, however, formed both by niche expansion and niche changes. The only ubiquitous response to a change in the photosynthetic pathway within Panicoideae was a niche expansion of the C4 species into regions with higher growing season temperatures, but without a withdrawal from the inherited climate niche. Other patterns varied among the tribes, as macro-climatic niche evolution in the American tribe Paspaleae differed from the pattern supported in the globally distributed tribe Paniceae and at family level.Fil: Aagesen, Lone. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Biganzoli, Fernando. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Métodos Cuantitativos y Sistemas de Información; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bena, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Godoy Bürki, Ana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Zuloaga, Fernando Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentin

Paspalum stellatum Humb. & Bonpl. ex Flüggé

ResistenciapublishedVersio

Refractive-index sensing with ultra-thin plasmonic nanotubes

We study the refractive-index sensing properties of plasmonic nanotubes with a dielectric core and ultra-thin metal shell. The few-nm thin metal shell is described by both the usual Drude model and the nonlocal hydrodynamic model to investigate the effects of nonlocality. We derive an analytical expression for the extinction cross section and show how sensing of the refractive index of the surrounding medium and the figure-of-merit are affected by the shape and size of the nanotubes. Comparison with other localized surface plasmon resonance sensors reveals that the nanotube exhibits superior sensitivity and comparable figure-of-merit

Estudio Cooperativo sobre Umbral Crónico de Estimulación, Valorado como Carga Transferida en 153 Pacientes con Marcapasos Definitivo y Electrodos de Alta Biocompatibilidad

En la presente comunicación se exponen los resultados de la evaluación del umbral crónico de estimulación en 153 pacientes con marcapasos definitivo y electrodos de superficie fractal. El grupo estudiado, estaba constituído por 58 mujeres y 95 hombres, a quienes se había implantado un marcapasos definitivo, multiprogramable, unicameral (VVIM), con electrodo bipolar endocavitario de superficie fractal, ubicado en apex de ventrículo derecho (Biotronik, TIR 60 BP, con 6 mm2 de superficie de estimulación). El análisis de los datos obtenidos (expresados como carga transferida, en microcoulombios), demostró muy bajos umbrales crónicos: 0.81 µc, SD ± 0.39, (rango 0.65 - 2.54 µc). Considerando un margen de seguridad del 100% por sobre el umbral crónico hallado, se determina que en la población estudiada, la reprogramación de la salida de 4.8 voltios a 2.4 voltios (en ambos casos con 0.5 milisegundos de ancho de pulso), es posible en el 73.8% de los casos (113 pacientes), permitiendo un incremento en el tiempo de prestación para todo el grupo del orden del 20.9%. Las consecuencias de esta modificación en la carga transferida inciden directamente en el paciente (optimización del sensado y recambio de generador menos frecuente), y socialmente (un ahorro de recursos que pueden ser empleados en otros aspectos de la salud pública)

Estudio Cooperativo sobre Umbral Crónico de Estimulación, Valorado como Carga Transferida en 153 Pacientes con Marcapasos Definitivo y Electrodos de Alta Biocompatibilidad

En la presente comunicación se exponen los resultados de la evaluación del umbral crónico de estimulación en 153 pacientes con marcapasos definitivo y electrodos de superficie fractal. El grupo estudiado, estaba constituído por 58 mujeres y 95 hombres, a quienes se había implantado un marcapasos definitivo, multiprogramable, unicameral (VVIM), con electrodo bipolar endocavitario de superficie fractal, ubicado en apex de ventrículo derecho (Biotronik, TIR 60 BP, con 6 mm2 de superficie de estimulación). El análisis de los datos obtenidos (expresados como carga transferida, en microcoulombios), demostró muy bajos umbrales crónicos: 0.81 µc, SD ± 0.39, (rango 0.65 - 2.54 µc). Considerando un margen de seguridad del 100% por sobre el umbral crónico hallado, se determina que en la población estudiada, la reprogramación de la salida de 4.8 voltios a 2.4 voltios (en ambos casos con 0.5 milisegundos de ancho de pulso), es posible en el 73.8% de los casos (113 pacientes), permitiendo un incremento en el tiempo de prestación para todo el grupo del orden del 20.9%. Las consecuencias de esta modificación en la carga transferida inciden directamente en el paciente (optimización del sensado y recambio de generador menos frecuente), y socialmente (un ahorro de recursos que pueden ser empleados en otros aspectos de la salud pública)

Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June\u2013September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 +/-2.1Mm-1, with a maximum of 15.9Mm-1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption \uc5ngstr\uf6m exponent (\ue5ABS/ retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct \ue5ABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the \ue5ABS retrieved from offline MWAA measurements

Angstrom-Scale Distance Dependence of Antenna-Enhanced Vibrational Signals

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Five Nuclear Loci Resolve the Polyploid History of Switchgrass (Panicum virgatum L.) and Relatives

Polyploidy poses challenges for phylogenetic reconstruction because of the need to identify and distinguish between homoeologous loci. This can be addressed by use of low copy nuclear markers. Panicum s.s. is a genus of about 100 species in the grass tribe Paniceae, subfamily Panicoideae, and is divided into five sections. Many of the species are known to be polyploids. The most well-known of the Panicum polyploids are switchgrass (Panicum virgatum) and common or Proso millet (P. miliaceum). Switchgrass is in section Virgata, along with P. tricholaenoides, P. amarum, and P. amarulum, whereas P. miliaceum is in sect. Panicum. We have generated sequence data from five low copy nuclear loci and two chloroplast loci and have clarified the origin of P. virgatum. We find that all members of sects. Virgata and Urvilleana are the result of diversification after a single allopolyploidy event. The closest diploid relatives of switchgrass are in sect. Rudgeana, native to Central and South America. Within sections Virgata and Urvilleana, P. tricholaenoides is sister to the remaining species. Panicum racemosum and P. urvilleanum form a clade, which may be sister to P. chloroleucum. Panicum amarum, P. amarulum, and the lowland and upland ecotypes of P. virgatum together form a clade, within which relationships are complex. Hexaploid and octoploid plants are likely allopolyploids, with P. amarum and P. amarulum sharing genomes with P. virgatum. Octoploid P. virgatum plants are formed via hybridization between disparate tetraploids. We show that polyploidy precedes diversification in a complex set of polyploids; our data thus suggest that polyploidy could provide the raw material for diversification. In addition, we show two rounds of allopolyploidization in the ancestry of switchgrass, and identify additional species that may be part of its broader gene pool. This may be relevant for development of the crop for biofuels