272 research outputs found

    Discriminación entre poblaciones de abejas (apis mellifera L.) del sur de España, centro de Portugal y Madeira

    Get PDF
    Tradicionalmente se ha considerado que las abejas que viven en la Península Ibérica pertenecen a la raza Apis mellifera iberica, que se encuentra emparentada con la raza A. m. intermissa que coloniza el norte de África y la raza A. m. mellifera originaria de Europa occidental. Las abejas obreras procedentes de España y Portugal, se han descrito como animales de color azabache, con pilosidad y tomento de tamaño mediano, y una probóscide bastante larga; encontrando algunos autores que los animales del sur tenían una pilosidad más corta y una probóscide más larga, que sus familiares procedentes del norte. En el presente trabajo hemos estudiado 34 muestras de abejas obreras procedentes de dos zonas de nuestra península (el sur de España y el centro de Portugal), y del Archipiélago de Madeira, para rastrear la existencia de posibles diferencias morfológicas. Los resultados muestran que los animales constituyen tres grupos morfológicos, identificables mediante un análisis canónico. Uno de ellos incluye a los procedentes del centro de Portugal, otro está formado por los oriundos de Córdoba, y el tercero está constituido por los procedentes de la isla de Madeira y de la Sierra de Cazorla

    Biometric study of apis mellifera population from central Portugal and Madeira

    Get PDF
    Las abejas melíferas que habitan en la Península Ibérica han sido descritas tradicionalmente como pertenecientes a la raza Apis mellifera iberica. La raza iberica está constituida por animales de color oscuro y de un gran vigor, su comportamiento es algo nervioso y la enjambraz .n se considera como moderada. Desde un punto de vista morfológico, son pocos los trabajos en los que se han estudiado estos seres vivos, incluyendo la bibliografía existente descripciones más o menos extensas de los que habitan en la región mediterránea, Asturias y la Submeseta Norte. Si admitimos que diferentes condiciones climáticas han debido de tener efectos selectivos sobre las características de estos insectos, resulta muy interesante estudiar abejas procedentes de diferentes localizaciones, para conocer la variabilidad existente. En el presente trabajo hemos estudiado 16 caracteres morfológicos, en 18 muestras de abejas obreras oriundas del centro de Portugal y de la isla de Madeira. Los resultados indican que las abejas del centro de Portugal constituyen un grupo morfológico, en el que no se aprecian grandes diferencias entre las distintas localizaciones geográficas. Los animales procedentes de Madeira también forman un conjunto morfológico, en el que, cuando se estudia de forma conjunta con las muestras procedentes de Portugal, el análisis canónico muestra un solapamiento parcial de las poblaciones

    Niveles inmunitarios contra fiebre aftosa en bovinos del Urabá antioqueño 1978 - 1985

    Get PDF
    This paper discribes the results of the protection status of cattle against Foot-and- Mouth Disease (FMD) found during the 1978 to 1985 period. One of the vaccination cycles was considered for each year, and a statistical representative random sample was calculated for both, young and adult cattle. Animals were bled at day 90 postvaccination and neutralizing antibody titers against FMD types A and 0 were assayed by neutralization test in microtiter plates, using BHK21 cells. The value of 1.5 log was considered to discriminate protected from unprotected cattle. During the analyzed period, in young cattle, the percentages of protection against the virus type A ranged from 25.6 to 64.4%, and against the type 0 from 27.9 to 74.2%. The estimated percentages of protection in adult cattle, ranged from 23.1 to 87.7% against the virus type A and from 42.8 to 88.8% against the type 0. The estimated percentages of protection found in adult cattle were, in most of the years, higher (P < 0.05) than those found in young cattle. In the latter category, the inmune response against the virus type 0 was higher than that against the type A. These differences were statistically significant (P < 0.05) in 1979, 1980, 1981 and 1982. From the above results a satisfactory protection status against FMD was deduced, specially since 1980 which has been reflected in a remarkable reduction of FMD outbreaks in this region. Besides, it was confirmed the efficacy of massive and systematic vaccination procedures, complemented by other actions such as control of cattle movement and severe epidemiologic surveillance.Se describen los resultados de la evaluación continuada del estado de protección contra fiebre aftosa (F.A.) en la población bovina del Urabá antioqueño, durante 1978 a 1985. Para cada año se consideró uno de los ciclos de vacunación y se determinó una muestra estadísticamente representativa de bovinos jóvenes y adultos. Estos fueron sangrados a los 90 días post-vacunación y sus títulos de anticuerpos contra los virus tipos A y O evaluados mediante la técnica de seroneutralización en placa, utilizando células BHK sub 21. Se consideró el valor 1.5 log como título discriminante entre protección y no protección. Durante el período analizado, en los bovinos jóvenes los valores estimados de protección contra el virus tipo A oscilaron entre 25.6 y 64.4 por ciento y contra el tipo O, entre 27.9 y 74.2 por ciento. En los adultos, los valores estimados de protección fluctuaron entre 23.1 y 87.7 por ciento para el virus tipo A y entre 42.8 y 88.8 por ciento para el virus tipo O. El procentaje estimado de bovinos adultos protegidos contra F.A. fue en la mayoría de los años superior (P menor que 0.05) al encontrado en los jóvenes, en los cuales la respuesta inmune fue mayor para el virus tipo O que para el tipo A, siendo la diferencia estadísticamente significativa (P menor que 0.05) en los años 1979, 1980, 1981 y 1982. De los resultados se dedujo que la protección contra F.A. fue satisfactoria, especialmente a partir de 1980, reflejada en una disminución notoria del número de focos en la región, lo cual confirma la eficacia de los programas masivos y sistemáticos de vacunación, complementados con medidas de control de movilización de animales y una drástica vigilancia epidemiológica.Ganado de leche-Ganadería lech

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

    Get PDF
    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

    Get PDF
    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

    Get PDF
    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry

    Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

    Get PDF
    A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 8 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for the direct production of charginos and neutralinos in final states with three leptons and missing transverse momentum is presented. The analysis is based on 20.3 fb−1 of s√ = 8 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations and limits are set in R-parity-conserving phenomenological Minimal Supersymmetric Standard Models and in simplified supersymmetric models, significantly extending previous results. For simplified supersymmetric models of direct chargino (χ˜±1) and next-to-lightest neutralino (χ˜02) production with decays to lightest neutralino (χ˜01) via either all three generations of sleptons, staus only, gauge bosons, or Higgs bosons, (χ˜±1) and (χ˜02) masses are excluded up to 700 GeV, 380 GeV, 345 GeV, or 148 GeV respectively, for a massless (χ˜01

    Search for a CP-odd Higgs boson decaying to Zh in pp collisions at √s=8TeV with the ATLAS detector

    Get PDF
    A search for a heavy, CP-odd Higgs boson, A, decaying into a Zboson and a 125GeV Higgs boson, h, with the ATLAS detector at the LHC is presented. The search uses proton–proton collision data at a centre-of-mass energy of 8TeV corresponding to an integrated luminosity of 20.3fb−1. Decays of CP-even hbosons to ττor bbpairs with the Zboson decaying to electron or muon pairs are considered, as well as h →bbdecays with the Zboson decaying to neutrinos. No evidence for the production of an Aboson in these channels is found and the 95% confidence level upper limits derived for σ(gg→A) ×BR(A →Zh) ×BR(h →f¯f)are 0.098–0.013pb for f=τand 0.57–0.014pb for f=bin a range of mA=220–1000GeV. The results are combined and interpreted in the context of two-Higgs-doublet models. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons

    Observation of top-quark pair production in association with a photon and measurement of the ttγ production cross section in pp collisions at √s = 7 TeV using the ATLAS detector

    Get PDF
    A search is performed for top-quark pairs (tt) produced together with a photon (γ) with transverse energy greater than 20 GeV using a sample of tt candidate events in final states with jets, missing transverse momentum, and one isolated electron or muon. The data set used corresponds to an integrated luminosity of 4.59 fb −1 of proton-proton collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. In total, 140 and 222 ttγ candidate events are observed in the electron and muon channels, to be compared to the expectation of 79 +/- 26 and 120 +/- 39 non-ttγ background events, respectively. The production of ttγ events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The ttγ production cross section times the branching ratio (BR) of the single-lepton decay channel is measured in a fiducial kinematic region within the ATLAS acceptance. The measured value is σ (fid/tty) × BR = 63 +/- 8(stat) (+17/-13)(syst) +/- 1 lumi fb per lepton flavor, in good agreement with the leading-order theoretical calculation normalized to the next-to-leading-order theoretical prediction of 48 +/- 10 fb
    corecore