4,690 research outputs found

    The envelope of the power spectra of over a thousand \delta Scuti stars. The Tˉeff\bar{T}_{eff}-Îœmax\nu_{max} scaling relation

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    CoRoT and Kepler high-precision photometric data allowed the detection and characterization of the oscillation parameters in stars other than the Sun. Moreover, thanks to the scaling relations, it is possible to estimate masses and radii for thousands of solar-type oscillating stars. Recently, a \Delta\nu - \rho relation has been found for \delta Scuti stars. Now, analyzing several hundreds of this kind of stars observed with CoRoT and Kepler, we present an empiric relation between their frequency at maximum power of their oscillation spectra and their effective temperature. Such a relation can be explained with the help of the \kappa-mechanism and the observed dispersion of the residuals is compatible with they being caused by the gravity-darkening effect

    Community-focused strategies.

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    This article introduces the notion of community-focused strategies to refer to the set of actions, activities and policies that firms undertake to establish connections or relational links with one or more target communities of (potential) customers. Drawing on social identity theory and strategy research, this study begins with a proposed taxonomy of different community-focused strategies. Then it illustrates how such strategies contribute to the creation of competitive advantage and explores their boundary conditions. Finally, the authors offer implications for theory development and practice, as well as suggestions for further research.Communities; Competitive advantage; Firm strategies; Identity;

    Evidence of amplitude modulation due to Resonant Mode Coupling in the delta Scuti star KIC5892969

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    A study of the star KIC5892969 observed by the Kepler satellite is presented. Its three highest amplitude modes present a strong amplitude modulation. The aim of this work is to investigate amplitude variations in this star and their possible cause. Using the 4 years-long observations available, we obtained the frequency content of the full light curve. Then, we studied the amplitude and phase variations with time using shorter time stamps. The results obtained are compared with the predicted ones for resonant mode coupling of an unstable mode with lower frequency stable modes. Our conclusion is that resonant mode coupling is consistent as an amplitude limitation mechanism in several modes of KIC5892969 and we discuss to which extent it might play an important role for other delta Scuti stars

    Clues for the existence of two K1(1270)K_1(1270) resonances

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    The axial vector meson K1(1270)K_1(1270) was studied within the chiral unitary approach, where it was shown that it has a two-pole structure. We reanalyze the high-statistics WA3 experiment K−p→K−π+π−pK^- p\to K^-\pi^+\pi^- p at 63 GeV, which established the existence of both K1(1270)K_1(1270) and K1(1400)K_1(1400), and we show that it clearly favors our two-pole interpretation. We also reanalyze the traditional K-matrix interpretation of the WA3 data and find that the good fit of the data obtained there comes from large cancellations of terms of unclear physical interpretation.Comment: published version in PRD; typos corrected; title changed to "Clues for the existence of two K1(1270)K_1(1270) resonances

    Mobility through Heterogeneous Networks in a 4G Environment

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    Serving and Managing users in a heterogeneous environment. 17th WWRF Meeting in Heidelberg, Germany, 15 - 17 November 2006. [Proceeding presented at WG3 - Co-operative and Ad-hoc Networks]The increase will of ubiquitous access of the users to the requested services points towards the integration of heterogeneous networks. In this sense, a user shall be able to access its services through different access technologies, such as WLAN, Wimax, UMTS and DVB technologies, from the same or different network operators, and to seamless move between different networks with active communications. In this paper we propose a mobility architecture able to support this users’ ubiquitous access and seamless movement, while simultaneously bringing a large flexibility to access network operators
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