4,387 research outputs found

    Sexual Segregation in Iberian Noctule Bats

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    Sexual segregation during the breeding season is common in many temperate bat species, and may be related to sex-specific thermoregulatory, microclimatic, or energetic requirements. We compiled capture data for 3 species of Nyctalus (noctule bats) obtained over .20 years to study reproductive and migratory strategies of these species in southwestern Europe. Within the Iberian Peninsula, several different strategies regarding sex distribution and migratory behavior were observed within each of the 3 Nyctalus species. In the northern part of Iberia there are populations of the 3 species composed of males all year-round with females appearing only during the mating season. Reproduction by females in this area has not been confirmed. In central and southern Iberia there are breeding populations in which sexual segregation occurs only at the roosts or at a regional scale, possibly with females located at lower elevations during the breeding season. Female-biased, long-distance migration is likely to be the cause of sexual segregation in populations of N. noctula and N. leisleri in northern and central Iberia, but not of N. lasiopterus, absent in central Europe. For this latter species, segregation by elevation also could occur in northern Iberia. The Iberian Peninsula is a good example of how breeding strategies and migratory behavior in bats can be very flexible and vary across relatively small geographical scales.Peer reviewe

    Electroweak radiative corrections to e+e−→ttˉhe^+e^- \to t \bar{t} h at linear colliders

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    We calculate the O(αew){\cal O}(\alpha_{{\rm ew}}) electroweak radiative corrections to e+e−→ttˉhe^+ e^- \to t \bar{t} h at a electron-positron linear collider (LC) in the standard model. We analyze the dependence of the O(αew){\cal O}(\alpha_{{\rm ew}}) corrections on the Higgs boson mass mhm_{h} and colliding energy s\sqrt{s}, and find that the corrections significantly decrease or increase the Born cross section depending on the colliding energy. The numerical results show that the O(αew){\cal O}(\alpha_{{\rm ew}}) relative correction is strongly related to the Higgs boson mass when s=500GeV\sqrt{s}=500 GeV, and for mh=150GeVm_h = 150 GeV the relative correction ranges from -31.3% to 2.3% as the increment of the colliding energy from 500 GeV to 2 TeV.Comment: 16 pages, 7 figure

    Experiencias en el Uso de Códigos Neutrónicos en la Docencia en Ingeniería Nuclear

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    [ES] El equipo de innovación docente SEERISN (Simulación en la Enseñanza de Radiaciones Ionizantes y Seguridad Nuclear) de la UPV ha retomado sus actividades con el objetivo de abordar desde un punto de vista global la necesidad de formar a los estudiantes en el uso de códigos neutrónicos para el cálculo de reactores nucleares tal como se demanda desde las empresas del sector nuclear. El análisis de las diferentes actividades que ya se estaban realizando ha puesto de manifiesto la necesidad de revisar estas actividades para una introducción gradual y específica del uso de códigos neutrónicos en varias asignaturas de una manera sistemática y consciente, estableciendo grados de dificultad crecientes adecuados a cada titulación incluyendo medidas de evaluación del grado de consecución de las mismas. Este proceso se ha planteado en diferentes etapas y acciones. En este trabajo se presenta la primera fase de implantación en una asignatura de grado y los resultados obtenidos.[ES] The teaching innovation team SEERISN (Simulation in the Teaching of Ionizing Radiation and Nuclear Safety) of the UPV has resumed its activities with the aim of addressing, from a global point of view, the need to train students in the use of neutron codes to the calculation of nuclear reactors as demanded by companies in the nuclear sector. The analysis of the different activities that were already being carried out has revealed the need to review these activities for a gradual and specific introduction of the use of neutronic codes in various subjects in a systematic and conscious manner, establishing increasing degrees of difficulty appropriate to each qualification including evaluation measures of the degree of achievement of the same. This process has been proposed in different stages and actions. This paper presents the first phase of implementation in one subject for a degree and the results obtained.Barrachina, T.; Juste, B.; Miró, R.; Verdú, G. (2023). Experiencias en el Uso de Códigos Neutrónicos en la Docencia en Ingeniería Nuclear. Editorial Universitat Politècnica de València. 679-687. https://doi.org/10.4995/INRED2023.2023.1656867968

    O(αs){\cal O}(\alpha_{s}) QCD and O(αew){\cal O}(\alpha_{ew}) electroweak corrections to ttˉh0t\bar{t}h^0 production in γγ\gamma \gamma collision

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    We calculate the O(αs){\cal O}(\alpha_{s}) QCD and O(αew){\cal O}(\alpha_{{\rm ew}}) electroweak one-loop corrections in the Standard Model framework, to the production of an intermediate Higgs boson associated with ttˉt\bar{t} pair via γγ\gamma \gamma fusion at an electron-positron linear collider (LC). We find the O(αs){\cal O}(\alpha_{s}) QCD corrections can be larger than the O(αew){\cal O}(\alpha_{{\rm ew}}) electroweak ones, with the variations of the Higgs boson mass mhm_{h} and e+e−e^+e^- colliding energy s\sqrt{s}. Both corrections may significantly decrease or increase the Born cross section. The numerical results show that the relative corrections from QCD to the process \eep may reach 34.8%, when s=800\sqrt{s}=800 GeV and mh=200m_h=200 GeV, while those from electroweak can be -13.1%, -15.8% and -12.0%, at s=800\sqrt{s} = 800 GeV, 1 TeV and 2 TeV respectively.Comment: 38 pages, 16 figure

    Higgs production in association with top quark pair at e+e- colliders in theories of higher dimensional gravity

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    The models of large extra compact dimensions, as suggested by Arkani-Hamed, Dimopoulos and Dvali, predict exciting phenomenological consequences with gravitational interactions becoming strong at the TeV scale. Such theories can be tested at the existing and future colliders. In this paper, we study the contribution of virtual Kaluza-Klein excitations in the process e+e−→ttˉHe^+e^- \to t \bar t H at future linear collider (NLC). We find that the virtual exchange KK gravitons can modify the cross-section σ(e+e−→ttˉH)\sigma(e^+e^- \to t \bar t H) significantly from its Standard Model value and will allow the effective string scale to be probed up to 7.9 TeV.Comment: 10 pages, Latex, 4 postscript figure

    Report of the 2005 Snowmass Top/QCD Working Group

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    This report discusses several topics in both top quark physics and QCD at an International Linear Collider (ILC). Issues such as measurements at the ttˉt\bar{t} threshold, including both theoretical and machine requirements, and the determination of electroweak top quark couplings, are reviewed. New results concerning the potential of a 500 GeV e+e−e^+e^- collider for measuring WtbWtb couplings and the top quark Yukawa coupling are presented. The status of higher order QCD corrections to jet production cross sections, heavy quark form factors, and longitudinal gauge boson scattering, needed for percent-level studies at the ILC, are reviewed. A new study of the measurement of the hadronic structure of the photon at a γγ\gamma\gamma collider is presented. The effects on top quark properties from several models of new physics, including composite models, Little Higgs theories, and CPT violation, are studied.Comment: 39 pages, many figs; typos fixed and refs added. Contributed to the 2005 International Linear Collider Physics and Detector Workshop and 2nd ILC Accelerator Workshop, Snowmass, Colorado, 14-27 Aug 200

    LHC Discovery Potential for Non-Standard Higgs Bosons in the 3b Channel

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    In a variety of well motivated models, such as two Higgs Doublet Models (2HDMs) and the Minimal Supersymmetric Standard Model (MSSM), there are neutral Higgs bosons that have significantly enhanced couplings to b-quarks and tau leptons in comparison to those of the SM Higgs. These so called non-standard Higgs bosons could be copiously produced at the LHC in association with b quarks, and subsequently decay into b-quark pairs. However, this production channel suffers from large irreducible QCD backgrounds. We propose a new search strategy for non-standard neutral Higgs bosons at the 7 TeV LHC in the 3b's final state topology. We perform a simulation of the signal and backgrounds, using state of the art tools and methods for different sets of selection cuts, and conclude that neutral Higgs bosons with couplings to b-quarks of about 0.3 or larger, and masses up to 400 GeV, could be seen with a luminosity of 30 fb^{-1}. In the case of the MSSM we also discuss the complementarity between the 3b channel and the inclusive tau pair channel in exploring the supersymmetric parameter space.Comment: 14 pages, 3 figures, 4 tables, references added, published versio

    Radiative corrections to Higgs-boson production in association with top-quark pairs at e+ e- colliders

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    We have calculated the complete O(alpha) and O(alpha_s) radiative corrections to the Higgs-production process e+ e- -> t anti-t H in the Standard Model. This process is particularly interesting for the measurement of the top-quark Yukawa coupling at a future e+ e- collider. The calculation of the O(alpha) corrections is described in some detail including, in particular, the treatment of the soft and collinear singularities. The discussion of numerical results focuses on the total cross section as well as on angular and energy distributions of the outgoing particles. The electroweak corrections turn out to be sizable and can reach the order of +/-10%. They result from cancellations between electromagnetic, fermionic, and weak bosonic corrections, each of which are of the order of +/-10%.Comment: 32 pages, LaTeX, 12 postscript figure

    El día de la semana en la exploración de la orientación en el tiempo

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    Sr. Editor: La exploración de la orientación en el tiempo (OT) se aplica de forma habitual en el examen del estado mental y en especial, en el cribado del deterioro cognitivo. En un trabajo previo, nuestro grupo aportó una nueva técnica de exploración de la OT, aplicando una pregunta abierta («dígame la fecha de hoy lo más completa posible») y cuantificando las respuestas espontáneas del paciente mediante la suma de 2 escalas, una semántica que puntúa los campos de la fecha que el paciente genera (día del mes —D—, mes —M—, año —A— y día de la semana —S—), y otra episódica, que puntúa la información episódica correcta para cada campo..

    Effects Of Length, Complexity, And Grammatical Correctness On Stuttering In Spanish-Speaking Preschool Children

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    Purpose: To explore the effects of utterance length, syntactic complexity, and grammatical correctness on stuttering in the spontaneous speech of young, monolingual Spanish-speaking children. Method: Spontaneous speech samples of 11 monolingual Spanish-speaking children who stuttered, ages 35 to 70 months, were examined. Mean number of syllables, total number of clauses, utterance complexity (i.e., containing no clauses, simple clauses, or subordinate and/or conjoined clauses), and grammatical correctness (i.e., the presence or absence of morphological and syntactical errors) in stuttered and fluent utterances were compared. Results: Findings revealed that stuttered utterances in Spanish tended to be longer and more often grammatically incorrect, and contain more clauses, including more subordinate and/or conjoined clauses. However, when controlling for the interrelatedness of syllable number and clause number and complexity, only utterance length and grammatical incorrectness were significant predictors of stuttering in the spontaneous speech of these Spanish-speaking children. Use of complex utterances did not appear to contribute to the prediction of stuttering when controlling for utterance length. Conclusions: Results from the present study were consistent with many earlier reports of English-speaking children. Both length and grammatical factors appear to affect stuttering in Spanish-speaking children. Grammatical errors, however, served as the greatest predictor of stuttering.Communication Sciences and Disorder
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