On complexified analytic Hamiltonian flows and geodesics on the space of Kahler metrics

In the case of a compact real analytic symplectic manifold M we describe an approach to the complexification of Hamiltonian flows [Se, Do1, Th1] and corresponding geodesics on the space of Kahler metrics. In this approach, motivated by recent work on quantization, the complexified Hamiltonian flows act, through the Grobner theory of Lie series, on the sheaf of complex valued real analytic functions, changing the sheaves of holomorphic functions. This defines an action on the space of (equivalent) complex structures on M and also a direct action on M. This description is related to the approach of [BLU] where one has an action on a complexification M_C of M followed by projection to M. Our approach allows for the study of some Hamiltonian functions which are not real analytic. It also leads naturally to the consideration of continuous degenerations of diffeomorphisms and of Kahler structures of M. Hence, one can link continuously (geometric quantization) real, and more general non-Kahler, polarizations with Kahler polarizations. This corresponds to the extension of the geodesics to the boundary of the space of Kahler metrics. Three illustrative examples are considered. We find an explicit formula for the complex time evolution of the Kahler potential under the flow. For integral symplectic forms, this formula corresponds to the complexification of the prequantization of Hamiltonian symplectomorphisms. We verify that certain families of Kahler structures, which have been studied in geometric quantization, are geodesic families.Comment: final versio

On the BKS pairing for Kahler quantizations of the cotangent bundle of a Lie group

A natural one-parameter family of K\"ahler quantizations of the cotangent bundle $T^*K$ of a compact Lie group $K$, taking into account the half-form correction, was studied in \cite{FMMN}. In the present paper, it is shown that the associated Blattner-Kostant-Sternberg (BKS) pairing map is unitary and coincides with the parallel transport of the quantum connection introduced in our previous work, from the point of view of \cite{AdPW}. The BKS pairing map is a composition of (unitary) coherent state transforms of $K$, introduced in \cite{Ha1}. Continuity of the Hermitian structure on the quantum bundle, in the limit when one of the K\"ahler polarizations degenerates to the vertical real polarization, leads to the unitarity of the corresponding BKS pairing map. This is in agreement with the unitarity up to scaling (with respect to a rescaled inner product) of this pairing map, established by Hall.Comment: final version, to appear in Journ. Funct. Ana

Geometric quantization, complex structures and the coherent state transform

It is shown that the heat operator in the Hall coherent state transform for a compact Lie group $K$ is related with a Hermitian connection associated to a natural one-parameter family of complex structures on $T^*K$. The unitary parallel transport of this connection establishes the equivalence of (geometric) quantizations of $T^*K$ for different choices of complex structures within the given family. In particular, these results establish a link between coherent state transforms for Lie groups and results of Hitchin and Axelrod, Della Pietra and Witten.Comment: to appear in Journal of Functional Analysi

Puntos fijos y ligas europeas de fútbol: discusión de las trayectorias de los equipos de fútbol europeos por la densidad de puntos fijos

All soccer teams visit their final standing ranks before their final journeys. This work analyzes the trajectory of European soccer teams toward their final standing ranks for the seasons between 2004/2005 and 2012/2013. We studied six professional soccer leagues (England, Germany, Italy, the Netherlands, Portugal, and Spain). Referring to the fixed point theorem and to quantile regressions, this article concludes that the Dutch league is the one characterized by the largest value for its fixed point, exhibiting more rank changes than the others with the same percentage of played journeys. The English and Italian leagues were identified as the leagues in which a higher share of teams tended to stabilize at their final standings’ ranks at the earliest journeys.Todos los equipos de fútbol visitan sus clasificaciones finales antes de las últimas jornadas de liga. Este trabajo analiza la trayectoria de los equipos de fútbol europeos hacia sus posiciones finales en las temporadas entre 2004/2005 y 2012/2013. Se estudiaron seis ligas profesionales de fútbol (Inglaterra, Alemania, Italia, Países Bajos, Portugal y España). Utilizando el teorema del punto fijo y regresiones cuantílicas, este artículo concluye que la liga holandesa es la que se caracteriza por el mayor valor para su punto fijo, exhibiendo más cambios de ranking que los otros con el mismo porcentaje de partidos jugados. Las ligas inglesas e italianas fueron identificadas como las ligas en las que una mayor proporción de equipos tendió a estabilizarse antes en las que serían sus posiciones finales en la clasificación

Management of Disused Radium Sources in Latin America and the Caribbean

This paper describes the radium sources conditioning operation carried out in Latin American and the Caribbean by a team of the Brazilian federal research institute CDTN, as part of an International Atomic Energy Agency's hands-on assistance project to safely condition disused sources in developing countries. This initiative was spawned by the perceived hazard associated with the use of radium sources, caused mainly by the high likelihood that these sources leak during their use due to the accumulation of the radon gas in their interior. The conditions under which these sources are often stored in the target countries, without proper documentation, mixed with different radiation sources and under precarious conditions, urged the Agency to start this program at the end of 1996. The conditioning process starts with a pre-mission to the candidate country, when a place is selected for the forthcoming operation, suggest improvements in the local available infrastructure is suggest ed and gather the most complete information available about the country's source inventory is collected. The operation consists of transferring the sources from their original shields to sturdy multi-barrier packages, which are put under the control of the local nuclear authority. As part of the quality assurance program applied to this project, the relevant information about the conditioned inventory is recorded and made available to the host country, to the IAEA and to the conditioning team

Syk-dependent Phosphorylation of CLEC-2: A Novel Mechanism of Hem-Immunoreceptor Tyrosine-Based Activation Motif Signaling

The C-type lectin-like receptor CLEC-2 signals via phosphorylation of a single cytoplasmic YXXL sequence known as a hem-immunoreceptor tyrosine-based activation motif (hemITAM). In this study, we show that phosphorylation of CLEC-2 by the snake toxin rhodocytin is abolished in the absence of the tyrosine kinase Syk but is not altered in the absence of the major platelet Src family kinases, Fyn, Lyn, and Src, or the tyrosine phosphatase CD148, which regulates the basal activity of Src family kinases. Further, phosphorylation of CLEC-2 by rhodocytin is not altered in the presence of the Src family kinase inhibitor PP2, even though PLCγ2 phosphorylation and platelet activation are abolished. A similar dependence of phosphorylation of CLEC-2 on Syk is also seen in response to stimulation by an IgG mAb to CLEC-2, although interestingly CLEC-2 phosphorylation is also reduced in the absence of Lyn. These results provide the first definitive evidence that Syk mediates phosphorylation of the CLEC-2 hemITAM receptor with Src family kinases playing a critical role further downstream through the regulation of Syk and other effector proteins, providing a new paradigm in signaling by YXXL-containing receptors

Palms use a bluffing strategy to avoid seed predation by rats in Brazil.

The goal of this study was to ascertain why the production of variable seediness is advantageous for Attalea phalerata palms. Our hypothesis was that variation reduces seed predation by the spiny rats Thrichomys pachyurus and Clyomys laticeps. Although there is a positive correlation between endocarp size and number of seeds, endocarps sometimes contain more or fewer seeds than expected; palms bluff about the number of seed per endocarp. Therefore, rats do not know how many seeds an endocarp contains. To model rats? predating behavior, we applied Charnov?s Marginal Value Theorem. The model shows that rats attack endocarps only when the energy gain is higher than the energy available in the habitat. Hence, it is not advantageous to eat all the seeds inside an endocarp. This explains why 45 percent of forest endocarps and 35 percent of savanna endocarps were still viable after predation. We then applied the model to two simulated endocarp populations with less variability in the number of seeds per endocarp size and determined that viable diaspores after predation were reduced to 15 percent. With less variability, palms cannot bluff about the number of seeds inside endocarps and predators can predict accurately how many seeds they should try to eat. Uncertainty about the number of seeds diminished predation but gave selective advantage to multiseeded fruits. Therefore, the bluffing strategy would be evolutionarily stable only if it were counterbalanced by other forces. Otherwise, predators would win the bluffing game

Herança citoplasmática de pesos ao nascimento e à desmama em bovinos da raça Charolesa.

Efeitos da herança citoplasmática sobre os pesos ao nascimento (PN;N=1521) e aos 205 dias de idade de bezerros da raça Charolesa

Automated, high accuracy classification of Parkinsonian disorders: a pattern recognition approach

Progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and idiopathic Parkinson’s disease (IPD) can be clinically indistinguishable, especially in the early stages, despite distinct patterns of molecular pathology. Structural neuroimaging holds promise for providing objective biomarkers for discriminating these diseases at the single subject level but all studies to date have reported incomplete separation of disease groups. In this study, we employed multi-class pattern recognition to assess the value of anatomical patterns derived from a widely available structural neuroimaging sequence for automated classification of these disorders. To achieve this, 17 patients with PSP, 14 with IPD and 19 with MSA were scanned using structural MRI along with 19 healthy controls (HCs). An advanced probabilistic pattern recognition approach was employed to evaluate the diagnostic value of several pre-defined anatomical patterns for discriminating the disorders, including: (i) a subcortical motor network; (ii) each of its component regions and (iii) the whole brain. All disease groups could be discriminated simultaneously with high accuracy using the subcortical motor network. The region providing the most accurate predictions overall was the midbrain/brainstem, which discriminated all disease groups from one another and from HCs. The subcortical network also produced more accurate predictions than the whole brain and all of its constituent regions. PSP was accurately predicted from the midbrain/brainstem, cerebellum and all basal ganglia compartments; MSA from the midbrain/brainstem and cerebellum and IPD from the midbrain/brainstem only. This study demonstrates that automated analysis of structural MRI can accurately predict diagnosis in individual patients with Parkinsonian disorders, and identifies distinct patterns of regional atrophy particularly useful for this process