Search results for "Divergence"
showing 10 items of 257 documents
Genetic relationships between sympatric and allopatric Coregonus ciscoes in North and Central Europe
2021
Abstract Background Sympatric speciation along ecological gradients has been studied repeatedly, in particular in freshwater fishes. Rapid post-glacial ecological divergence has resulted in numerous endemic species or ecologically distinct populations in lakes of the temperate zones. Here, we focus on the Baltic cisco (Coregonus albula) complex, to study the genetic similarity among two pairs of sympatric autumn- and spring-spawning populations from post-glacial German Lakes Stechlin and Breiter Luzin. For comparison, we included a similar pair of sympatric populations from the Swedish Lake Fegen. We wanted to explore potential genetic similarities between the three sympatric cisco populati…
Blind deconvolution using TV regularization and Bregman iteration
2005
In this paper we formulate a new time dependent model for blind deconvolution based on a constrained variational model that uses the sum of the total variation norms of the signal and the kernel as a regularizing functional. We incorporate mass conservation and the nonnegativity of the kernel and the signal as additional constraints. We apply the idea of Bregman iterative regularization, first used for image restoration by Osher and colleagues [S.J. Osher, M. Burger, D. Goldfarb, J.J. Xu, and W. Yin, An iterated regularization method for total variation based on image restoration, UCLA CAM Report, 04-13, (2004)]. to recover finer scales. We also present an analytical study of the model disc…
Phylogeography and genetic divergence of some lymnaeid snails, intermediate hosts of human and animal fascioliasis with special reference to lymnaeid…
1997
Abstract A population genetic study using starch gel electrophoresis was performed on populations of several species of lymnaeid snails acting as intermediate hosts for Fasciola hepatica (Trematoda, Plathyhelminth). Lymnaea viatrix was collected in 16 sites from the Bolivian Northern Altiplano. L. cubensis were obtained in one site from Venezuela, one site from Guadeloupe, three sites from Cuba and one site from the Dominican Republic. L. truncatula were collected in one site from France, one from Portugal and one from Morocco. Multilocus enzyme electrophoresis (MEE) were determined for 282 snails at 18 loci. A complete monomorphism was encountered at each geographic site. However, among th…
Extropy: Complementary Dual of Entropy
2015
This article provides a completion to theories of information based on entropy, resolving a longstanding question in its axiomatization as proposed by Shannon and pursued by Jaynes. We show that Shannon's entropy function has a complementary dual function which we call "extropy." The entropy and the extropy of a binary distribution are identical. However, the measure bifurcates into a pair of distinct measures for any quantity that is not merely an event indicator. As with entropy, the maximum extropy distribution is also the uniform distribution, and both measures are invariant with respect to permutations of their mass functions. However, they behave quite differently in their assessments…
Wages and prices in early Catalan industrialisation
2014
Catalonia was the only Mediterranean region among the early followers of the British Industrial Revolution in the second third of the nineteenth century. The roots of this industrialisation process can be traced back to the seventeenth and eighteenth centuries when the Catalan economy became successfully integrated in international trade and the region enjoyed an intensification of its agrarian and proto-industrial activities. These capitalist developments were subsequently reinforced by a successful printed calico manufacturing business concentrated in the city of Barcelona. Although the factory system was largely adopted by the cotton industry in the 1840s, the diffusion of the spinning j…
Approximations in Statistics from a Decision-Theoretical Viewpoint
1987
The approximation of the probability density p(.) of a random vector x∊X by another (possibly more convenient) probability density q(.) which belongs to a certain class Q is analyzed as a decision problem where the action space is the class Qof available approximations, the relevant uncertain event is the actual value of the vector x and the utility function is a proper scoring rule. The logarithmic divergence is shown to play a rather special role within this approach. The argument lies entirely within a Bayesian framework.
Existence of viscosity solutions to two-phase problems for fully nonlinear equations with distributed sources
2018
In this paper we construct a viscosity solution of a two-phase free boundary problem for a class of fully nonlinear equation with distributed sources, via an adaptation of the Perron method. Our results extend those in [Caffarelli, 1988], [Wang, 2003] for the homogeneous case, and of [De Silva, Ferrari, Salsa, 2015] for divergence form operators with right hand side.
The on-line curvilinear component analysis (onCCA) for real-time data reduction
2015
Real time pattern recognition applications often deal with high dimensional data, which require a data reduction step which is only performed offline. However, this loses the possibility of adaption to a changing environment. This is also true for other applications different from pattern recognition, like data visualization for input inspection. Only linear projections, like the principal component analysis, can work in real time by using iterative algorithms while all known nonlinear techniques cannot be implemented in such a way and actually always work on the whole database at each epoch. Among these nonlinear tools, the Curvilinear Component Analysis (CCA), which is a non-convex techni…
Implicit learning and statistical learning: one phenomenon, two approaches.
2006
The domain-general learning mechanisms elicited in incidental learning situations are of potential interest in many research fields, including language acquisition, object knowledge formation and motor learning. They have been the focus of studies on implicit learning for nearly 40 years. Stemming from a different research tradition, studies on statistical learning carried out in the past 10 years after the seminal studies by Saffran and collaborators, appear to be closely related, and the similarity between the two approaches is strengthened further by their recent evolution. However, implicit learning and statistical learning research favor different interpretations, focusing on the forma…
Divergence and introgression among the virilis group of Drosophila
2022
AbstractSpeciation with gene flow is now widely regarded as common. However, the frequency of introgression between recently diverged species and the evolutionary consequences of gene flow are still poorly understood. The virilis group of Drosophila contains around a dozen species that are geographically widespread and show varying levels of pre-zygotic and post-zygotic isolation. Here, we utilize de novo genome assemblies and whole-genome sequencing data to resolve phylogenetic relationships and describe patterns of introgression and divergence across the group. We suggest that the virilis group consists of three, rather than the traditional two, subgroups. We found evidence of pervasive p…