On a nonlocal degenerate parabolic problem

Conditions for the existence and uniqueness of weak solutions for a class of nonlinear nonlocal degenerate parabolic equations are established. The asymptotic behaviour of the solutions as time tends to infinity are also studied. In particular, the finite time extinction and polynomial decay properties are proved

Convergence of the Crank-Nicolson-Galerkin finite element method for a class of nonlocal parabolic systems with moving boundaries

The aim of this paper is to establish the convergence and error bounds to the fully discrete solution for a class of nonlinear systems of reaction-diffusion nonlocal type with moving boundaries, using a linearized Crank-Nicolson-Galerkin finite element method with polynomial approximations of any degree. A coordinate transformation which fixes the boundaries is used. Some numerical tests to compare our Matlab code with some existing moving finite elements methods are investigated

Aktivität und Vorkommen geflügelter Blattläuse auf Freilandpaprika in Spanien

Horizontal mosaic-green-tile traps were placed in various pepper-growing areas of Spain: Aranjuez and Arganda del Rey (Madrid), Balboa (Badajoz), Cadreita (Pamplona), Mendavia and Sartaguda (Logroño), Montañana (Zaragoza), Pueblo Nuevo (Valencia) and Torrepacheco (Murcia). These mosaic-greentraps resembled much better the pepper canopy than the commonly used yellow water traps, as indicated by absorbance spectrophotometry. Sampling was extended throughout the pepper crop cycle during 1990, 1991 and 1992. Over that time, 14,363 aphids, belonging to 99 species/taxa were captured. Aphis was the principal genus captured: 57.5 % of the total (17 % belonging to the species Aphis fabae (Scopoli)). Other abundant species were: Myzus (Nectarosiphon) persicae (Sulzer) (7.46 %), Diuraphis noxia (Mordvilko) (5.23 %), Brachycaudus spp. (3.73 %), Sitobion avenae (F.) (2.51 %), Macrosiphum euphorbiae (Thomas) (2.46 %), Rhopalosiphum spp. (2.20 %) and Therioaphis spp. (1.99 %). The species included in the genus Aphis were the most abundant in all the regions sampled, although M. (N.) persicae was also predominant in the Zaragoza and Pamplona region, and D. noxia was frequently found in the Madrid region. A first aphid peak was observed soon after transplanting (May–June) in most of the regions and years sampled.Horizontale mosaikgrüne Farbfallen wurden in verschiedenen Paprika-Anbaugebieten in Spanien aufgestellt: Aranjuez und Arganda del Rey (Madrid), Balbao (Badajoz), Cadreita (Pamplona), Mendavia und Sartaguda (Logroño), Montañana (Zaragoza), Pueblo Nuevo (Valencia) und Torrepacheco (Murcia). Diese mosaikgrünen Fallen ähnelten sehr viel besser den Farben des Paprikabestandes als die üblicherweise eingesetzten gelben Wasserfallen wie durch Absorptionsspektrometrie festgestellt wurde. Die Probennahmen erfolgten während der ganzen Wachstumsphasen des Paprikas in den Jahren 1990, 1991 und 1992. In diesen Zeiträumen konnten 14363 Blattläuse gefangen werden, die 99 Arten/Taxa angehörten. Die Gattung Aphis wurde mit 57,5 % am häufigsten gefangen, 17 % gehörten zur Art Aphis fabae (Scopoli). Andere häufig vorkommende Arten waren: Myzus (Nectarosiphon) persicae (Sulzer) (7,46 %), Diuraphis noxia (Mordvilko) (5,23 %), Brachycaudus spp. (3,73 %), Sitobion avenae (F.) (2,51 %), Macrosiphum euphorbiae (Thomas) (2,46 %), Rhopalosiphum spp. (2,20 %) und Therioaphis spp. (1,99 %). Die zur Gattung Aphis gehörenden Arten waren in allen beprobten Regionen am häufigsten, obgleich M. (N.) persicae in den Regionen Zaragoza und Pamplona auch sehr häufig vorkam. D. noxia trat häufig in der Madrider Region auf. Ein erster Höhehoug punkt des Blattlausaufretens wurde in den meisten Regionen und Jahren schon bald nach dem Auspflanzen (Mai–Juni) beobachtet.This work was supported by the Interministerial Commision for Science and Technology of Spain (Comisión Interministerial de Ciencia y Tecnología, grant AGR91-0448)..Peer reviewe

Disentangling signatures of selection before and after European colonization in latin Americans

Throughout human evolutionary history, large-scale migrations have led to intermixing (i.e., admixture) between previously separated human groups. Although classical and recent work have shown that studying admixture can yield novel historical insights, the extent to which this process contributed to adaptation remains underexplored. Here, we introduce a novel statistical model, specific to admixed populations, that identifies loci under selection while determining whether the selection likely occurred post-admixture or prior to admixture in one of the ancestral source populations. Through extensive simulations, we show that this method is able to detect selection, even in recently formed admixed populations, and to accurately differentiate between selection occurring in the ancestral or admixed population. We apply this method to genome-wide SNP data of ∼4,000 individuals in five admixed Latin American cohorts from Brazil, Chile, Colombia, Mexico, and Peru. Our approach replicates previous reports of selection in the human leukocyte antigen region that are consistent with selection post-admixture. We also report novel signals of selection in genomic regions spanning 47 genes, reinforcing many of these signals with an alternative, commonly used local-ancestry-inference approach. These signals include several genes involved in immunity, which may reflect responses to endemic pathogens of the Americas and to the challenge of infectious disease brought by European contact. In addition, some of the strongest signals inferred to be under selection in the Native American ancestral groups of modern Latin Americans overlap with genes implicated in energy metabolism phenotypes, plausibly reflecting adaptations to novel dietary sources available in the Americas

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors