107,246 research outputs found

    The present development of time service in Brazil, with the application of the TV line-10 method for coordination and synchronization of atomic clocks

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    Various methods presently used for the dissemination of time at several levels of precision are described along with future projects in the field. Different aspects of time coordination are reviewed and a list of future laboratories participating in a National Time Scale will be presented. A Brazilian Atomic Time Scale will be obtained from as many of these laboratories as possible. The problem of intercomparison between the Brazilian National Time Scale and the International one will be presented and probable solutions will be discussed. Needs related to the TV Line-10 method will be explained and comments will be made on the legal aspects of time dissemination throughout the country

    Generalized CP Invariance and the Yukawa sector of Two-Higgs Models

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    We analyze generalized CP symmetries of two-Higgs doublet models, extending them from the scalar to the fermion sector of the theory. We show that, with a single exception, those symmetries imply massless fermions. The single model which accommodates a fermionic mass spectrum compatible with experimental data possesses a remarkable feature. It displays a new type of spontaneous CP violation, which occurs not in the scalar sector responsible for the symmetry breaking mechanism but, rather, in the fermion sector.Comment: RevTex, 4 pages, no figures Version2: Remarkable additional conclusion => title & text changes; section adde

    The Challenges of Strategic Human Resources Management in Southeast Asian Universities

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    Nowadays the Higher Education Institutions face major challenges in its development. Demanding from different actors and the orientation of the research, more oriented to innovation and value creation, request news capacities to answer to that. Southeast Asia shows a strong economic growth with a large increase in GDP and a growing improvement in the position of The Human Development Index promoted by United Nations. This reality creates a different pressure on the higher education institutions in southeast Asia that requires a change in the universities, in the way they implement the mission and in the requested capacities, specially the human resources capacities. In this way, a new paradigm and model of human resources management for southeast higher education institutions need be developed to create the conditions to answer to this new reality, where the main analysis variables will be talent, performance, motivation and retention, coaching, cross cultural, integrity and permanent adaptability and flexibility. The main objective of this communication is to reflect and contextualize in terms of theoretical models where we find the assumptions for the implementation of strategic human resources management for southeast Asian universities. What kind of profile is request for the staff in this new reality? What we need to change in human resources management? How can this change be implemented? What HRM tools are most relevant to this reality? These are the main issues on which we will reflect with a critical thinking approach in order to present a set of clues to southeast Asian universities according to our analysis and interpretation, as Portuguese and European

    Discrete and continuous symmetries in multi-Higgs-doublet models

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    We consider the Higgs sector of multi-Higgs-doublet models in the presence of simple symmetries relating the various fields. We construct basis invariant observables which may in principle be used to detect these symmetries for any number of doublets. A categorization of the symmetries into classes is required, which we perform in detail for the case of two and three Higgs doublets.Comment: 13 pages, RevTex, references adde

    A Model of Growth with Intertemporal Knowledge Externalities, Augmented with Contemporaneous Knowledge Externalities

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    The present model is essentially Romer’s (1990) model of endogenous growth with intertemporal knowledge externalities, augmented with contemporaneous knowledge externalities to give a richer explanation of the growth process. Both types of knowledge spillovers seem essential to capturing the features of knowledge in a model of growth. Introducing synchronic complementarities and knowledge externalities across inventive firms immediately creates the possibility of multiple equilibria and threshold effects in the present model. Another advantage of this theoretical formulation is that it allows for an analysis of the effects on steady-state growth of a variety of technology policies relying on changing knowledge complementarities parameters.Endogenous growth, innovation, knowledge complementarities, knowledge externalities, general equilibrium

    Magnetic quantum phase transitions of the antiferromagnetic J_{1}-J_{2} Heisenberg model

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    We obtain the complete phase diagram of the antiferromagnetic J1J_{1}-J2J_{2} model, 0≤α=J2/J1≤10\leq \alpha = J_2/J1 \leq 1, within the framework of the O(N)O(N) nonlinear sigma model. We find two magnetically ordered phases, one with N\' eel order, for α≤0.4\alpha \leq 0.4, and another with collinear order, for α≥0.6\alpha\geq 0.6, separated by a nonmagnetic region, for 0.4≤α≤0.60.4\leq \alpha \leq 0.6, where a gapped spin liquid is found. The transition at α=0.4\alpha=0.4 is of the second order while the one at α=0.6\alpha=0.6 is of the first order and the spin gaps cross at α=0.5\alpha=0.5. Our results are exact at N→∞N\rightarrow\infty and agree with numerical results from different methods.Comment: 4 pages, 5 figure

    Aghion And Howitt’s Basic Schumpeterian Model Of Growth Through Creative Destruction: A Geometric Interpretation

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    The present paper takes a geometric approach to characterize the competitive forces behind innovation and dynamic general equilibria determination in the model of growth through creative destruction constructed by Aghion and Howitt (1992). All can be comprehended intuitively from the geometric presentation. While Aghion and Howitt‘s original presentation of the basic model was essentially analytical, often with fairly intricate mathematics focusing on stationary equilibria with positive growth, the geometric presentation taken here has the benefit of making what in the original paper was a bundle of mathematical notation more comprehensible intuitively.Endogenous growth, innovation, creative destruction, general equilibrium

    Doubly-periodic array of bubbles in a Hele-Shaw cell

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    Exact solutions are presented for a doubly-periodic array of steadily moving bubbles in a Hele-Shaw cell when surface tension is neglected. It is assumed that the bubbles either are symmetrical with respect to the channel centreline or have fore-and-aft symmetry, or both, so that the relevant flow domain can be reduced to a simply connected region. By using conformal mapping techniques, a general solution with any number of bubbles per unit cell is obtained in integral form. Several examples are given, including solutions for multi-file arrays of bubbles in the channel geometry and doubly-periodic solutions in an unbounded cell.Comment: 15 pages, 12 figure

    Implications of the LHC two-photon signal for two-Higgs-doublet models

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    We study the implications for Two Higgs Doublet Models of the recent announcement at the LHC giving a tantalizing hint for a Higgs boson of mass 125 GeV decaying into two photons. We require that the experimental result be within a factor of two of the theoretical Standard Model prediction, and analyze the type I and type II models as well as the lepton-specific and flipped models, subject to this requirement. It is assumed that there is no new physics other than two Higgs doublets. In all of the models, we display the allowed region of parameter space taking the recent LHC announcement at face value, and we analyze the W+W−W^+W^-, ZZZZ, bˉb\bar{b}b and τ+τ−\tau^+\tau^- expectations in these allowed regions. Throughout the entire range of parameter space allowed by the γγ\gamma\gamma constraint, the number of events for Higgs decays into WWWW, ZZZZ and bbˉb \bar b are not changed from the Standard Model by more than a factor of two. In contrast, in the Lepton Specific model, decays to τ+τ−\tau^+ \tau^- are very sensitive across the entire γγ\gamma \gamma-allowed region.Comment: Latex, 6 pages, 4 figures; v2 - added 2 reference
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