459 research outputs found

    Genetics of oviposition success of a thelytokous fairyfly parasitoid, Anagrus delicatus

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    The foraging behaviour of the salt-marsh parasitoid, Anagrus delicatus (Hymenoptera: Mymaridae), is distinguished by few eggs laid per patch of hosts and frequent dispersal among patches. We investigated the within-population genetic variability in six quantitative traits associated with this unusual behaviour: fecundity (lifetime number of eggs), time on a patch, number of ovipositions per patch, oviposition rate, ovipositor length and tibia length (a measure of body size). Forty-one wasp isolines were initiated from single parthenogenetic females from three isolated salt marshes, and were maintained for up to eight generations in the greenhouse. We estimated the genetic variance and broad-sense heritability (h2) of these traits and tested trait means for differences among isolines (genetic variation) and sites (geographical variation). We found significant genetic variability among isolines for all traits except oviposition rate. The behavioural and morphological traits had similar levels of genetic variance, indicating that the evolvability (ability to respond to selection) of the traits is similarly high. However, the behavioural traits had higher residual variances, resulting in lower heritabilities. Only two traits had significant heritabilities. Fecundity, which is probably a good proxy for fitness, ceteris paribus, varied from on average 26 to 40 eggs per isoline and had the highest h2, 0.47±0.16 (mean±SE). Ovipositor length had an h2 of 0.36±0.17. These results suggest that the traits comprising the foraging strategy of A. delicatus should be amenable to selection (e.g. isolines could be selected that lay more eggs per host patch and consequently visit fewer patches). Genetic correlations among traits were numerous and positive. One important prediction from these data is that selection for larger wasps will result in large offspring with greater egg loads and higher oviposition rates. Wasps with this combination of attributes are likely to be more efficient natural enemies for use in biological control. In addition, there was no significant divergence (genetic or otherwise) in wasp morphology or behaviour among the three sites, even though they were separated by 8 km or more. © 1996 The Genetical Society of Great Britain

    Contrasting plant adaptation strategies to latitude in the native and invasive range of Spartina alterniflora.

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    Biological invasions offer model systems of contemporary evolution. We examined trait differences and evolution across geographic clines among continents of the intertidal grass Spartina alterniflora within its invasive and native ranges. We sampled vegetative and reproductive traits in the field at 20 sites over 20° latitude in China (invasive range) and 28 sites over 17° in the US (native range). We grew both Chinese and US plants in a greenhouse common garden for three years. Chinese plants were ~ 15% taller, ~10% denser, and set up to four times more seed than US plants in both the field and common garden. The common-garden experiments showed a striking genetic cline of seven-fold greater seed-set at higher latitudes in the introduced but not the native range. In contrast, there was a slight genetic cline in some vegetative traits in the native but not the introduced range. Our results are consistent with others showing that introduced plants can evolve rapidly in the new range. S. alterniflora has evolved different trait clines in the native and introduced range, showing the importance of phenotypic plasticity and genetic control of change during the invasion process

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ Îł, H → Z Z∗ →4l and H →W W∗ →lÎœlÎœ. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined ïŹts probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Standalone vertex ïŹnding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

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    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon Ό\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, ΌΌ\mu\mu or eΌe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

    Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

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    A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

    Perceived usefulness of a distributed community-based syndromic surveillance system: a pilot qualitative evaluation study

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    <p>Abstract</p> <p>Background</p> <p>We conducted a pilot utility evaluation and information needs assessment of the Distribute Project at the 2010 Washington State Public Health Association (WSPHA) Joint Conference. Distribute is a distributed community-based syndromic surveillance system and network for detection of influenza-like illness (ILI). Using qualitative methods, we assessed the perceived usefulness of the Distribute system and explored areas for improvement. Nine state and local public health professionals participated in a focus group (<it>n = 6</it>) and in semi-structured interviews (<it>n = 3</it>). Field notes were taken, summarized and analyzed.</p> <p>Findings</p> <p>Several emergent themes that contribute to the perceived usefulness of system data and the Distribute system were identified: 1) <it>Standardization: </it>a common ILI syndrome definition; 2) <it>Regional Comparability: </it>views that support county-by-county comparisons of syndromic surveillance data; 3) <it>Completeness: </it>complete data for all expected data at a given time; <it>4) Coverage: </it>data coverage of all jurisdictions in WA state; 5) <it>Context: </it>metadata incorporated into the views to provide context for graphed data; 6) <it>Trusted Data</it>: verification that information is valid and timely; and 7) <it>Customization: </it>the ability to customize views as necessary. As a result of the focus group, a new county level health jurisdiction expressed interest in contributing data to the Distribute system.</p> <p>Conclusion</p> <p>The resulting themes from this study can be used to guide future information design efforts for the Distribute system and other syndromic surveillance systems. In addition, this study demonstrates the benefits of conducting a low cost, qualitative evaluation at a professional conference.</p

    Measurement of the flavour composition of dijet events in pp collisions at root s=7 TeV with the ATLAS detector

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    This paper describes a measurement of the flavour composition of dijet events produced in pp collisions at &#8730;s=7 TeV using the ATLAS detector. The measurement uses the full 2010 data sample, corresponding to an integrated luminosity of 39 pb−1. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. Kinematic variables, based on the properties of displaced decay vertices and optimised for jet flavour identification, are used in a multidimensional template fit to measure the fractions of these dijet flavour states as functions of the leading jet transverse momentum in the range 40 GeV to 500 GeV and jet rapidity |y|&#60;2.1. The fit results agree with the predictions of leading- and next-to-leading-order calculations, with the exception of the dijet fraction composed of bottom and light flavour jets, which is underestimated by all models at large transverse jet momenta. The ability to identify jets containing two b-hadrons, originating from e.g. gluon splitting, is demonstrated. The difference between bottom jet production rates in leading and subleading jets is consistent with the next-to-leading-order predictions
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