3,837 research outputs found
Astrometry with the MCAO instrument MAD - An analysis of single-epoch data obtained in the layer-oriented mode
Context: Current instrument developments at the largest telescopes worldwide
have provisions for Multi-Conjugated Adaptive Optics (MCAO) modules. The large
field of view and more uniform correction provided by these systems is not only
highly beneficial for photometric studies but also for astrometric analysis of,
e.g., large dense clusters and exoplanet detection and characterization. The
Multi-conjugated Adaptive optics Demonstrator (MAD) is the first such
instrument and was temporarily installed and tested at the ESO/VLT in 2007. We
analyzed two globular cluster data sets in terms of achievable astrometric
precision. Data were obtained in the layer-oriented correction mode, one in
full MCAO correction mode with two layers corrected (NGC 6388) and the other
applying ground-layer correction only (47 Tuc). Aims: We aim at analyzing the
first available MCAO imaging data in the layer-oriented mode obtained with the
MAD instrument in terms of astrometric precision and stability. Methods: We
calculated Strehl maps for each frame in both data sets. Distortion corrections
were performed and the astrometric precision was analyzed by calculating mean
stellar positions over all frames and by investigation of the positional
residuals present in each frame after transformation to a
master-coordinate-frame. Results: The mean positional precision for stars
between K = 14-18 mag is ~1.2 mas in the full MCAO correction mode data of the
cluster NGC 6388. The precision measured in the GLAO data (47 Tuc) reaches ~1.0
mas for stars corresponding to 2MASS K magnitudes between 9 and 12. The
observations were such that stars in these magnitude ranges correspond to the
same detector flux range. The jitter movement used to scan a larger field of
view introduced additional distortions in the frames, leading to a degradation
of the achievable precision.Comment: 11 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
Adenosine and Immune Imbalance in Visceral Leishmaniasis: The Possible Role of Ectonucleotidases
Visceral leishmaniasis (VL) is the most severe form of leishmaniasis and is responsible for most Leishmania-associated deaths. VL represents a serious public health problem that affects many countries. The immune response in leishmaniasis is very complex and is poorly understood. The Th1 versus Th2 paradigm does not appear to be so clear in visceral leishmaniasis, suggesting that other immunosuppressive or immune-evasion mechanisms contribute to the pathogenesis of VL. It has been demonstrated that generation of adenosine, a potent endogenous immunosuppressant, by extracellular enzymes capable to hydrolyze adenosine tri-nucleotide (ATP) at the site of infection, can lead to immune impairment and contribute to leishmaniasis progression. In this regard, this paper discusses the unique features in VL immunopathogenesis, including a possible role for ectonucleotidases in leishmaniasis
Universal deformation rings of modules for generalized Brauer tree algebras of polynomial growth
Let be an arbitrary field, be a -algebra, and be a
-module. When it exists, the universal deformation ring
of is a -algebra whose local homomorphisms from to
parametrize the lifts of up to , where is any appropriate
complete, local commutative Noetherian -algebra. Symmetric special biserial
algebras, which coincide with Brauer graph algebras, can be viewed as
generalizing the blocks of finite type -modular group algebras. Bleher and
Wackwitz classified the universal deformation rings for all modules for
symmetric special biserial algebras with finite representation type. In this
paper, we begin to address the tame case. Specifically, let be a
symmetric special biserial algebra of polynomial growth which coincides with an
acyclic Brauer graph algebra. We classify the universal deformation rings for
those -modules with stable endomorphism ring isomorphic to .
The latter is a natural condition, since it guarantees the existence of the
universal deformation ring
A OMC e as limitações de políticas fiscais internas dos estados: o caso do Brasil
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas, Programa de Pós-Graduação em Direito, Florianópolis, 2010As recentes decisões proferidas no âmbito do Sistema de Solução de Controvérsias da OMC têm motivado a necessidade de avaliação específica pelos Estados Membros quando da elaboração de suas políticas fiscais internas. Alguns casos relevantes vêm sendo objeto de decisões que impactam diretamente na soberania fiscal interna como elemento de distorção de práticas comerciais internacionais. O estudo aplicado dos casos na OMC demonstra que as cláusulas da nação mais favorecida (NMF) e do tratamento nacional (TN) tem cada vez mais suscitado debates na formulação de políticas fiscais que, até então, eram reflexo intransponível da soberania estatal de cada Estado. A questão é ainda mais evidente no caso do Acordo sobre Subsídios e Medidas Compensatórias, tendo em vista a recente decisão proferida em matéria tributária no Caso FSC. Outras normas da OMC também possuem clara afetação tributária. A análise dos casos e das decisões torna-se fundamental para que os Estados evitem questionamentos e aplicação de decisões contra suas políticas internas. No caso do Brasil, afora os cada vez mais recorrentes questionamentos, é preciso avaliar a possibilidade de exposição de políticas estatais no âmbito tributário a questionamentos no âmbito do mecanismo de solução de controvérsias. Os países não dispõem mais de uma liberdade plena na configuração de políticas fiscais sem que observe a adequação de tais políticas às normas da OMC.The recent decisions in the Dispute Settlement System of the WTO has been motivating the assessment of specific necessity by the Members when elaborating their internal fiscal policies. Some of the relevant disputes have being object of decisions that generates direct impact in the internal fiscal sovereignty as element of distortive international trade practices. The study of the WTO demonstrates that the most favorite nation (MFN) and the national treatment (NT) clauses has been generating debates in the formulation of fiscal policies which, until then, were unbridgeable when dealing with internal sovereign of each Member. This situation has been still more evident regarding the Subsidy and Countervailing Measures Agreement (SCM), having in mind the evidence of the recent decision of the FSC case. Other WTO rules also present clear tax relation. The analysis of the disputes and its decisions is fundamental to the Members assess its policies in order to avoid questions and disputes regarding its internal tax measures. In the case of Brazil, besides the recent consults by the other Members, it is necessary to assess the possibility of exposure of certain tax policies to future consults and disputes in the Dispute Settlement System. The countries don#t have a full sovereignty and freedom to configure and define the fiscal policies without observing the relation of such policies regarding the WTO rules
Caracterización de los sistemas de producción de leche en la cuenca noreste de la Provincia de Córdoba, Argentina
91-97La cuenca lechera noreste es una de las principales regiones de mayor producción e industrialización de leche en la provincia de Córdoba. Sin embargo, no se dispone de una correcta caracterización de los sistemas de producción. Para ello se analizaron las diferencias en la composición de las dietas, la superficie de los establecimientos, la distancia al pavimento, el nivel de equipamiento, las mejoras de capital y la composición del rodeo en tambos con distinto nivel de producción. El objetivo de este estudio fue determinar las características de los tambos en la cuenca noreste de Córdoba a través de la estructura de producción, la base forrajera y la composición del rodeo. Se trabajó con una base de datos de 2070 tambos de los 3253 existentes en la provincia. Se establecieron dos categorías M1 y M2 que representan tambos de menor y mayor escala. A su vez, se subdividieron en alta y baja producción, resultando en cuatro modelos productivos. Esta cuenca se asienta en establecimientos con sistemas productivos con una alta heterogeneidad entre ellos que confiere una gran variabilidad en la zona. El modelo de tambos pequeños y de menor producción presenta una base forrajera compuesta principalmente por forraje alfalfa. El modelo de tambos pequeños y de alta producción presenta una estructura productiva con mayores mejoras y un alto porcentaje de alfalfa y silo. El modelo de tambos grandes y de baja producción se caracteriza por utilizar una dieta con baja participación de forraje silo y concentrados
Evaluacion economica de una plantacion de avellano europeo localizada en la Region de Maule
83 p.El avellano europeo es un frutal menor cuyo destino es mayormente el mercado internacional y la superficie plantada ha aumentado significativamente en los últimos años. En Chile se concentra principalmente en la zona central, pero concretamente en la Región del Maule.
Esta investigación comprende indicadores de rentabilidad y eficiencia económica para la producción de avellano europeo, variedad Barcelona. Los requerimientos para valorizar la inversión y costos del proyecto fueron recopilados a partir de productores localizados en la Región del Maule.
El proyecto fue ordenado de acuerdo a 3 etapas: establecimiento, formación y producción; con un horizonte de evaluación de 15 años, un tamaño de 100 hectáreas y sin valor residual.
Los precios fueron obtenidos de acuerdo a un promedio de las exportaciones FOB de Chile, pero para ser conservador se disminuyó en 10% el precio promedio, fijándolo en US 511.008; (TIR) de 22,67%; (IVAN) es 2,54%; y payback de 7; años. Cabe mencionar que el precio de quiebre es de 260 por Kg.; (MU) se comporta de manera creciente hasta el año 10, manteniéndose en $ 800 por Kg. y (RSC) obtiene un valor máximo el año 10 de 105,48%. Finalmente el cultivo de avellano europeo, bajo las condiciones planteadas, es rentable desde el punto de vista económico
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