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Search Results: 1 - 10 of 2703 matches for " Luigi; Baudoin "
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The impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica: consequences for the conservation of plant genetic resources
Daniel Barrantes,Gabriel Macaya,Luigi Guarino,Jean Pierre Baudoin
Revista de Biología Tropical , 2008,
Abstract: Plant populations may experience local extinction and at the same time new populations may appear in nearby suitable locations. Species may also colonize the same site on multiple occasions. Here, we examined the impact of local extinction and recolonization on the genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central valley of Costa Rica. We compared genetic diversity from the samples taken from the populations before and after extinction at 13 locations using microsatellite markers. Locations were classified according to the occurrence of extinction episodes during the previous five years into three groups: 1) populations that experienced extinction for more than one year, and were later recolonized (recolonized), 2) populations that did not experience local extinction (control), and 3) populations that did not experience local extinction during the study, but were cut to experimentally simulate extinction (experimental). Our data did not show a clear tendency in variation in allele frequencies, expected heterozygosity, and effective number of alleles within and between groups of populations. However, we found that the level of genetic differentiation between samples collected at different times at the same location was different in the three groups of populations. Recolonized locations showed the highest level of genetic differentiation (mean Fst= 0.2769), followed by control locations (mean Fst= 0.0576) and experimental locations (mean Fst= 0.0189). Similar findings were observed for Nei’s genetic distance between samples (di,j= 0.1786, 0.0400, and 0.0037, respectively). Our results indicate that genetic change in lima beans depends on the duration and frequency of local extinction episodes. These findings also showed that control populations are not in equilibrium. Implications of these results for the establishment of conservation strategies of genetic resources of lima beans are discussed. Rev. Biol. Trop. 56 (3): 1023-1041. Epub 2008 September 30. Las poblaciones de plantas pueden experimentar extinción local, y al mismo tiempo, pueden surgir a sus alrededores nuevas poblaciones. Algunas especies pueden colonizar el mismo sitio en múltiples ocasiones. Aquí examinamos el impacto de la extinción local y recolonización en la estructura genética de poblaciones silvestres del frijol lima (Phaseolus lunatus) en el valle Central de Costa Rica. Comparamos la diversidad genética de muestras tomadas en poblaciones, antes y después de la extinción, en 13 sitios, usando marcadores de microsatélite. Según los episodios de exti
The impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica: consequences for the conservation of plant genetic resources
Barrantes,Daniel; Macaya,Gabriel; Guarino,Luigi; Baudoin,Jean Pierre; Rocha,Oscar J;
Revista de Biología Tropical , 2008,
Abstract: plant populations may experience local extinction and at the same time new populations may appear in nearby suitable locations. species may also colonize the same site on multiple occasions. here, we examined the impact of local extinction and recolonization on the genetic structure of wild populations of lima beans (phaseolus lunatus) in the central valley of costa rica. we compared genetic diversity from the samples taken from the populations before and after extinction at 13 locations using microsatellite markers. locations were classified according to the occurrence of extinction episodes during the previous five years into three groups: 1) populations that experienced extinction for more than one year, and were later recolonized (recolonized), 2) populations that did not experience local extinction (control), and 3) populations that did not experience local extinction during the study, but were cut to experimentally simulate extinction (experimental). our data did not show a clear tendency in variation in allele frequencies, expected heterozygosity, and effective number of alleles within and between groups of populations. however, we found that the level of genetic differentiation between samples collected at different times at the same location was different in the three groups of populations. recolonized locations showed the highest level of genetic differentiation (mean fst= 0.2769), followed by control locations (mean fst= 0.0576) and experimental locations (mean fst= 0.0189). similar findings were observed for nei?s genetic distance between samples (di,j= 0.1786, 0.0400, and 0.0037, respectively). our results indicate that genetic change in lima beans depends on the duration and frequency of local extinction episodes. these findings also showed that control populations are not in equilibrium. implications of these results for the establishment of conservation strategies of genetic resources of lima beans are discussed. rev. biol. trop. 56 (3): 1023-1041. e
History and Analysis of 'Autumn Leaves'
Philippe Baudoin
Current Research in Jazz , 2012,
Abstract: Judging by the number of times it has been recorded, 'Autumn Leaves' is the most important non-American standard in the jazz repertoire. This article traces the composition's interesting history through the various published versions, and shows how its oft-studied musical structure has ties to classical compositions.
Chen series and Atiyah-Singer index theorem
Fabrice Baudoin
Mathematics , 2006,
Abstract: The purpose of this work is to give a new and short proof of Atiyah-Singer local index theorem by using heat semigroups approximations based on the truncature of Brownian Chen series.
Stochastic Taylor expansions and heat kernel asymptotics
Fabrice Baudoin
Mathematics , 2009,
Abstract: These notes focus on the applications of the stochastic Taylor expansion of solutions of stochastic differential equations to the study of heat kernels in small times. As an illustration of these methods we provide a new heat kernel proof of the Chern-Gauss-Bonnet theorem.
Conditioning and initial enlargement of filtration on a Riemannian manifold
Fabrice Baudoin
Mathematics , 2004, DOI: 10.1214/009117904000000126
Abstract: We extend to Riemannian manifolds the theory of conditioned stochastic differential equations. We also provide some enlargement formulas for the Brownian filtration in this nonflat setting.
Bakry-Emery meet Villani
Fabrice Baudoin
Mathematics , 2013,
Abstract: We study gradient estimates and convergence to the equilibrium for solutions of the parabolic equation which is associated to degenerate hypoelliptic diffusion operators. The method relies on a generalized Bakry-Emery type criterion that applies to this kind of operators. Our approach includes as a special case the kinetic Fokker-Planck equation and allows, in that case, to recover hypocoercive estimates obtained by Villani.
Sub-Laplacians and hypoelliptic operators on totally geodesic Riemannian foliations
Fabrice Baudoin
Mathematics , 2014,
Abstract: These notes are the basis of a course given at the Institut Henri Poincare in September 2014. We survey some recent results related to the geometric analysis of hypoelliptic diffusion operators on totally geodesic Riemannian foliations. We also give new applications to the study of hypocoercive estimates for Kolmogorov type operators.
Stochastic analysis on sub-Riemannian manifolds with transverse symmetries
Fabrice Baudoin
Mathematics , 2014,
Abstract: We prove a geometrically meaningful stochastic representation of the derivative of the heat semigroup on sub-Riemannian manifolds with tranverse symmetries. This representation is obtained from the study of Bochner-Weitzenbock type formulas for sub-Laplacians on 1-forms. As a consequence, we prove new hypoelliptic heat semigroup gradient bounds under natural global geometric conditions. The results are new even in the case of the Heisenberg group which is the simplest example of a sub-Riemannian manifold with transverse symmetries.
Stochastic differential equations driven by loops
Fabrice Baudoin
Mathematics , 2014,
Abstract: We study the properties of solutions of stochastic differential equations driven by processes generating loops in free nilpotent groups. We are in particular interested in existence and smoothness for the density.
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