244 research outputs found

    Molecular vibration in cold collision theory

    Full text link
    Cold collisions of ground state oxygen molecules with Helium have been investigated in a wide range of cold collision energies (from 1 Ό\muK up to 10 K) treating the oxygen molecule first as a rigid rotor and then introducing the vibrational degree of freedom. The comparison between the two models shows that at low energies the rigid rotor approximation is very accurate and able to describe all the dynamical features of the system. The comparison between the two models has also been extended to cases where the interaction potential He - O2_2 is made artificially stronger. In this case vibration can perturb rate constants, but fine-tuning the rigid rotor potential can alleviate the discrepancies between the two models.Comment: 11 pages, 3 figure

    Solar neutrino oscillation parameters after first KamLAND results

    Get PDF
    We analyze the energy spectrum of reactor neutrino events recently observed in the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) and combine them with solar and terrestrial neutrino data, in the context of two- and three-family active neutrino oscillations. In the 2-neutrino case, we find that the solution to the solar neutrino problem at large mixing angle (LMA) is basically split into two sub-regions, that we denote as LMA-I and LMA-II. The LMA-I solution, characterized by lower values of the squared neutrino mass gap, is favored by the global data fit. This picture is not significantly modified in the 3-neutrino mixing case. A brief discussion is given about the discrimination of the LMA-I and LMA-II solutions with future KamLAND data. In both the 2- and 3-neutrino cases, we present a detailed analysis of the post-KamLAND bounds on the oscillation parameters.Comment: Revised version. Two figures adde

    Red Queen Coevolution on Fitness Landscapes

    Full text link
    Species do not merely evolve, they also coevolve with other organisms. Coevolution is a major force driving interacting species to continuously evolve ex- ploring their fitness landscapes. Coevolution involves the coupling of species fit- ness landscapes, linking species genetic changes with their inter-specific ecological interactions. Here we first introduce the Red Queen hypothesis of evolution com- menting on some theoretical aspects and empirical evidences. As an introduction to the fitness landscape concept, we review key issues on evolution on simple and rugged fitness landscapes. Then we present key modeling examples of coevolution on different fitness landscapes at different scales, from RNA viruses to complex ecosystems and macroevolution.Comment: 40 pages, 12 figures. To appear in "Recent Advances in the Theory and Application of Fitness Landscapes" (H. Richter and A. Engelbrecht, eds.). Springer Series in Emergence, Complexity, and Computation, 201

    Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

    Get PDF
    Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

    Estereologia das glĂąndulas bulbouretrais do coelho (Oryctolagus cuniculus) e da cobaia (Cavia porcellus)

    Full text link
    As glĂąndulas bulbouretrais (GBU) no coelho (Oryctolagus cuniculus) e na cobaia (Cavia porcellus) desempenham um papel importante na fisiologia reprodutiva. No entanto, seus aspectos histolĂłgico e estereolĂłgico sĂŁo escassos. Assim, o objetivo desta pesquisa foi comparar caracterĂ­sticas estereolĂłgicas entre as GBU do coelho e da cobaia como um primeiro passo para a compreensĂŁo das variĂĄveis morfomĂ©tricas que participam nos processos reprodutivos. Foram utilizados 5 coelhos e 5 cobaias adultos machos, saudĂĄveis, obtidos do BiotĂ©rio da Universidade de La Frontera, Temuco, Chile. A regiĂŁo pĂ©lvica foi dissecada isolando-se a GBU de cada animal. Determinou-se o peso e o volume de cada glĂąndula. Estas foram fixadas em formalina tamponada durante 24 horas e incluĂ­das em paraplast. Cortes seriados de 4 ÎŒm de espessura foram corados com HE para anĂĄlise estereolĂłgica. A mĂ©dia de cĂ©lulas glandulares na GBU do coelho foi 19,50 x 10(5)mmÂł (DP 2,35) e da cobaia 10,57 x 10(5)mmÂł (DP 2,07) e a porcentagem mĂ©dia de tecido glandular foi de 25,52% (DP 2,20) e 17,20% (DP 3,33), respectivamente. Todos os parĂąmetros estereolĂłgicos comparados tiveram uma diferença estatisticamente significativa (p<0,0001). Estas diferenças poderiam ser explicadas porque hĂĄ maior proximidade celular do epitĂ©lio secretor, menor diĂąmetro do lĂșmen dos ĂĄcinos e da relação nĂșcleo citoplasma na GBU do coelho. Assim, os ĂĄcinos da GBU apresentam maior quantidade de cĂ©lulas por mmÂł do que na GBU do coelho. Estes parĂąmetros podem ser influenciados por fatores hormonais, etĂĄrios, sazonais e ambientais, entre outros. Considerar as caracterĂ­sticas morfolĂłgicas da GBU nesses animais poderia condicionar o ĂȘxito da reprodução por parte do macho

    Calibrating and adjusting expectations in life: A grounded theory on how elderly persons with somatic health problems maintain control and balance in life and optimize well-being

    Get PDF
    Aim: This study aims at exploring the main concern for elderly individuals with somatic health problems and what they do to manage this. Method: In total, 14 individuals (mean&#x200A;=&#x200A;74.2 years; range&#x200A;=&#x200A;68&#x2013;86 years) of both gender including hospitalized and outpatient persons participated in the study. Open interviews were conducted and analyzed according to grounded theory, an inductive theory-generating method. Results: The main concern for the elderly individuals with somatic health problems was identified as their striving to maintain control and balance in life. The analysis ended up in a substantive theory explaining how elderly individuals with somatic disease were calibrating and adjusting their expectations in life in order to adapt to their reduced energy level, health problems, and aging. By adjusting the expectations to their actual abilities, the elderly can maintain a sense of that they still have the control over their lives and create stability. The ongoing adjustment process is facilitated by different strategies and result despite lower expectations in subjective well-being. The facilitating strategies are utilizing the network of important others, enjoying cultural heritage, being occupied with interests, having a mission to fulfill, improving the situation by limiting boundaries and, finally, creating meaning in everyday life. Conclusion: The main concern of the elderly with somatic health problems was to maintain control and balance in life. The emerging theory explains how elderly people with somatic health problems calibrate their expectations of life in order to adjust to reduced energy, health problems, and aging. This process is facilitated by different strategies and result despite lower expectation in subjective well-being

    Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

    Get PDF
    The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements
    • 

    corecore