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

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.

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;

Community-based strategies in action: building and sustaining a product differentiation advantage

An important reason why individuals join groups or communities is to satisfy their needs for identity. Firms might exploit this societal tendency to gain a competitive advantage. Using the strategic approach adopted by Kiehl’s, a U.S. cosmetic producer and retailer, as a source of inspiration and illustration, this paper develops a novel theoretical framework to investigate how firms interact with communities to access privileged customers’ information, from which they can build a product differentiation advantage. We argue that by adhering and supporting a well-defined set of values, Kiehl’s both achieves community membership and strengthens the sense of identity that its target communities provide to their members. These investments prompt reciprocal community member behaviors, which the company channels into its customer knowledge development process. Finally, this article describes how firm–community interactions can protect the differentiation advantage by turning products into symbols of the communities to which its customers belong.Product differentiation, Customer knowledge development, Communities, Case study

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

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

The axial vector meson $K_1(1270)$ 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 $K^- p\to K^-\pi^+\pi^- p$ at 63 GeV, which established the existence of both $K_1(1270)$ and $K_1(1400)$, 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 $K_1(1270)$ resonances

Evidence of chaotic modes in the analysis of four delta Scuti stars

Since CoRoT observations unveiled the very low amplitude modes that form a flat plateau in the power spectrum structure of delta Scuti stars, the nature of this phenomenon, including the possibility of spurious signals due to the light curve analysis, has been a matter of long-standing scientific debate. We contribute to this debate by finding the structural parameters of a sample of four delta Scuti stars, CID 546, CID 3619, CID 8669, and KIC 5892969, and looking for a possible relation between these stars' structural parameters and their power spectrum structure. For the purposes of characterization, we developed a method of studying and analysing the power spectrum with high precision and have applied it to both CoRoT and Kepler light curves. We obtain the best estimates to date of these stars' structural parameters. Moreover, we observe that the power spectrum structure depends on the inclination, oblateness, and convective efficiency of each star. Our results suggest that the power spectrum structure is real and is possibly formed by 2-period island modes and chaotic modes