6,505 research outputs found
Analytic Reconstruction of heavy-quark two-point functions at O(\alpha_s^3)
Using a method previously developed, based on the Mellin-Barnes transform, we
reconstruct the two-point correlators in the vector, axial, scalar and
pseudoscalar channels from the Taylor expansion at q^2=0, the threshold
expansion at q^2=4m^2 and the OPE at q^2\rightarrow -\infty, where m is the
heavy quark mass. The reconstruction is analytic and systematic and is
controlled by an error function which becomes smaller as more terms in those
expansions are known.Comment: 19 pages, 11 figure
Mitochondria-encoded genes contribute to evolution of heat and cold tolerance in yeast
Genetic analysis of phenotypic differences between species is typically limited to interfertile species. Here, we conducted a genome-wide noncomplementation screen to identify genes that contribute to a major difference in thermal growth profile between two reproductively isolated yeast species, Saccharomyces cerevisiae and Saccharomyces uvarum. The screen identified only a single nuclear-encoded gene with a moderate effect on heat tolerance, but, in contrast, revealed a large effect of mitochondrial DNA (mitotype) on both heat and cold tolerance. Recombinant mitotypes indicate that multiple genes contribute to thermal divergence, and we show that protein divergence in COX1 affects both heat and cold tolerance. Our results point to the yeast mitochondrial genome as an evolutionary hotspot for thermal divergence.This work was supported by the NIH (grant GM080669) to J.C.F. Additional support to C.T.H. was provided by the USDA National Institute of Food and Agriculture (Hatch project 1003258), the National Science Foundation (DEB-1253634), and the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-SC0018409 and DE-FC02-07ER64494 to T. J. Donohue). C.T.H. is a Pew Scholar in the Biomedical Sciences and a Vilas Faculty Early Career Investigator, supported by the Pew Charitable Trusts and the Vilas Trust Estate, respectively. D.P. is a Marie Sklodowska-Curie fellow of the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 747775).Peer reviewe
Oldest Omaliini (Coleoptera: Staphylinidae: Omaliinae) Discovered in the Opaque Cretaceous Amber of Charentes
International audienceAppartenant aux Staphylinidae, la plus grande famille animale connue, les Omaliinae actuels constituent un groupe de scarabées très diversifié' et à large répartition mondiale. Des représentants des Omaliinae sont connus depuis le Jurassique inférieurà moyen, via des fossiles en compression, mais la tribu des Omaliini n'est identifiée qu'à partir du Cénozoïque. Duocalcar geminum Peris and Thayer gen. et sp. nov. est décrit comme le plus ancien fossile connu de cette tribu, et provient de l'ambre opaque du Crétacé moyen (Albien terminal) des Charentes (Sud-Ouest de la France). Sa découverte et sa description ont été rendues possibles grâce a' l'utilization des techniques d'imagerie RX synchrotron en contraste de phase, qui permettent une étude détaillée des inclusions d'insectes dans l'ambre opaque
Parental Expressed Emotion and Youth Psychopathology: New Directions for an Old Construct
Levels of parental expressed emotion (EE) are prospectively associated with the symptomatic course of a range of childhood psychiatric disorders. This article reviews the literature linking parental EE to youth psychopathology and proposes a novel framework for understanding its mechanisms of action. We find that, despite noteworthy methodological limitations, parental EE is linked consistently to a more deleterious course of mood, anxiety, and psychotic disorders in youth. Its mechanism of action is unknown. Models of "toxic family stress" (referring to frequent, sustained, and uncontrollable stress without protective influences) provide one framework for understanding how high EE environments interact with individual biological vulnerabilities to promote illness onset and recurrence. Research aimed at understanding biological responses (e.g., stress reactivity, arousal) to familial EE is needed. Such work may inform efforts to understand how EE affects the course of psychiatric disorders and may guide the development of novel interventions emphasizing emotion regulation strategies
Mitochondrial DNA and temperature tolerance in lager yeasts
A growing body of research suggests that the mitochondrial genome (mtDNA) is important for temperature adaptation. In the yeast genus Saccharomyces, species have diverged in temperature tolerance, driving their use in high- or low-temperature fermentations. Here, we experimentally test the role of mtDNA in temperature tolerance in synthetic and industrial hybrids (Saccharomyces cerevisiae × Saccharomyces eubayanus or Saccharomyces pastorianus), which cold-brew lager beer. We find that the relative temperature tolerances of hybrids correspond to the parent donating mtDNA, allowing us to modulate lager strain temperature preferences. The strong influence of mitotype on the temperature tolerance of otherwise identical hybrid strains provides support for the mitochondrial climactic adaptation hypothesis in yeasts and demonstrates how mitotype has influenced the world’s most commonly fermented beverage.This work was supported by the USDA National Institute of Food and Agriculture (Hatch project no. 1003258), the NSF (grant no. DEB-1253634), and in part by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science; nos. DE-SC0018409 and DE-FC02-07ER64494). E.P.B. was supported by a Louis and Elsa Thomsen Wisconsin Distinguished Graduate Fellowship. C.T.H. is a Pew Scholar in the Biomedical Sciences and a Vilas Faculty Early Career Investigator, supported by the Pew Charitable Trusts and the Vilas Trust Estate. D.P. is a Marie Sklodowska-Curie fellow of the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 747775). J.C.F. was supported by the NIH (no. GM080669)Peer Reviewe
Origin and evolution of fungus farming in wood-boring Coleoptera – a palaeontological perspective
Insect–fungus mutualism is one of the better-studied symbiotic interactions in nature. Ambrosia fungi are an ecological assemblage of unrelated fungi that are cultivated by ambrosia beetles in their galleries as obligate food for larvae. Despite recently increased research interest, it remains unclear which ecological factors facilitated the origin of fungus farming, and how it transformed into a symbiotic relationship with obligate dependency. It is clear from phylogenetic analyses that this symbiosis evolved independently many times in several beetle and fungus lineages. However, there is a mismatch between palaeontological and phylogenetic data. Herein we review, for the first time, the ambrosia system from a palaeontological perspective. Although largely ignored, families such as Lymexylidae and Bostrichidae should be included in the list of ambrosia beetles because some of their species cultivate ambrosia fungi. The estimated origin for some groups of ambrosia fungi during the Cretaceous concurs with a known high diversity of Lymexylidae and Bostrichidae at that time. Although potentially older, the greatest radiation of various ambrosia beetle lineages occurred in the weevil subfamilies Scolytinae and Platypodinae during the Eocene. In this review we explore the evolutionary relationship between ambrosia beetles, fungi and their host trees, which is likely to have persisted for longer than previously supposed.publishedVersio
Resummation of Threshold, Low- and High-Energy Expansions for Heavy-Quark Correlators
With the help of the Mellin-Barnes transform, we show how to simultaneously
resum the expansion of a heavy-quark correlator around q^2=0 (low-energy), q^2=
4 m^2 (threshold, where m is the quark mass) and q^2=-\infty (high-energy) in a
systematic way. We exemplify the method for the perturbative vector correlator
at O(alpha_s^2) and O(alpha_s^3). We show that the coefficients, Omega(n), of
the Taylor expansion of the vacuum polarization function in terms of the
conformal variable \omega admit, for large n, an expansion in powers of 1/n (up
to logarithms of n) that we can calculate exactly. This large-n expansion has a
sign-alternating component given by the logarithms of the OPE, and a fixed-sign
component given by the logarithms of the threshold expansion in the external
momentum q^2.Comment: 27 pages, 8 figures. We fix typos in Eqs. (18), (27), (55) and (56).
Results unchange
Review of the family Thanerocleridae (Coleoptera: Cleroidea) and the description of Thanerosus gen. nov. from Cretaceous amber using micro-CT scanning
The predaceous beetle family Thanerocleridae is one of the smallest families of Cleroidea. It comprises only 36 extant species widespread on all continents. Three more species have been described from Cretaceous ambers of Myanmar and France. The fourth fossil representative of Thanerocleridae is described herein. Thanerosus antiquus gen. and sp. nov. is based on one fossil specimen preserved in an amber piece from Upper Cretaceous Kachin amber. The holotype was imaged using an X-ray micro-CT system to obtain high-quality 3D images. A phylogenetic analysis based on 33 morphological characters supports the placement of the new genus at the basal position in a tree of Thanerocleridae, in the vicinity of extant Zenodosus Wolcott and three extinct Mesozoic genera with which the new fossil shares open procoxal and mesocoxal cavities and transverse procoxae. We offer here a key to all extant and extinct genera in the family together with a complete list of all valid thaneroclerid tax
On Renormalons and Landau Poles in Gauge Field Theories
It is shown that the commonly accepted relationship between the Landau
singularity in the running coupling constant of QED or QCD and the renormalon
singularities in the Borel sums of perturbation theory expansions is only a
particular feature of the restriction of the perturbative --function to
the one loop level.Comment: 11 pages, latex. One comment and one reference adde
Diez ideas potenciadoras para rendir al máximo en el deporte
El objetivo principal del presente trabajo es el planteamiento de una propuesta práctica de ideas potenciadoras en el deporte. Parte de la base de la PsicologĂa Cognitiva que plantea que existe una interpretaciĂłn de los acontecimientos que influyen en las emociones y la conducta, y la PsicologĂa Positiva que se centra en lo que se pretende conseguir en lugar de modificar aquello que funciona mal. Se toma como base las teorĂas cognitivas clásicas y más significativas, junto con diversas estrategias cognitivo-conductuales para aplicar conjuntamente a la implementaciĂłn de estas ideas en el entorno deportivo. Este tipo de herramientas aplicadas son cada vez más necesarias para profesionales de la psicologĂa del deporte en busca de la optimizaciĂłn del trabajo psicolĂłgico en un entorno cada vez más exigente
- …