FRW barotropic zero modes: Dynamical systems observability

The dynamical systems observability properties of barotropic bosonic and fermionic FRW cosmological oscillators are investigated. Nonlinear techniques for dynamical analysis have been recently developed in many engineering areas but their application has not been extended beyond their standard field. This paper is a small contribution to an extension of this type of dynamical systems analysis to FRW barotropic cosmologies. We find that determining the Hubble parameter of barotropic FRW universes does not allow the observability, i.e., the determination of neither the barotropic FRW zero mode nor of its derivative as dynamical cosmological states. Only knowing the latter ones correspond to a rigorous dynamical observability in barotropic cosmologyComment: 10 pages, 0 figure

Novel mechanisms to enhance the capacitance beyond the classical limits in capacitors with free-electron-like electrodes

The so-called negative electron compressibility refers to the lowering of the chemical potential of a metallic system when the carrier density increases. This effect has often been invoked in the past to explain the enhancement of the capacitance beyond the classical limits in capacitors with two-dimensional electron gases as electrodes. Based on experiments on strongly confined semiconductor quantum wells (QWs), it has been traditionally ascribed to the electron exchange energy as the main driving force. Recent research, however, has revealed that analogous effects can occur in other classes of materials systems, such as polar oxide interfaces, whose characteristics drastically depart from those of the previously considered cases. To rationalize these new results, it is necessary to revisit the established theory of confined electron gases, and test whether its conclusions are valid beyond the specifics of semiconductor-based QWs. Here we find, based on first-principles calculations of jellium slabs, that one must indeed be very careful when extrapolating existing results to other realistic physical systems. In particular, we identify a number of additional, previously overlooked mechanisms (e.g., related to the displacement of the electronic cloud and to the multiband structure of the delocalized gas), that enter into play and become new sources of negative capacitance in the weak-confinement regime. Our detailed analysis of these emerging contributions, supported by analytic models and multiple test cases, will provide a useful guidance in the ongoing quest for nanometric capacitors with enhanced performance.Comment: 24 pages, 19 figure

Environmental proactivity and firms' performance: Mediation effect of competitive advantages in Spanish wineries

The main aim of this paper is to show the extent to which environmental proactivity is able to generate competitive advantages in a firm in order to improve their economic-financial performance by introducing the role of managerial perception into the analysis. This study focuses on Spanish wineries and their environmental practices and covers a total of 4598 wineries with a sample of 142 valid responses during the month of November 2015. The results can be summarized as follows. Firstly, there is positive environmental proactivity in terms of obtaining both cost-based and differentiation-based competitive advantages. Likewise, this proactivity has a positive impact on the manager’s perception of performance. Secondly, obtaining differentiation-based competitive advantages has a positive impact on the manager’s perception of performance although a negative impact on performance itself. There is, however, no significant evidence of the impact of cost-based competitive advantages on financial performance nor on the perception of performance itself, nor the impact of environmental proactivity on financial performance

Modulation of Superconducting Properties by Ferroelectric Polarization in Confined FE-S-FE Films

We show that the electric polarization at the interface with ultrathin superconducting (S) films sandwiched between ferroelectric (FE) layers allows achievement of substantially stronger modulation of inner carrier density and superconducting transition temperature as compared to FE-S bilayers typically used in superconducting FETs. We find that not only the larger penetration depths but also the pairing symmetry should be responsible for the fact that the electric field effect in high temperature superconductors is much stronger than in conventional systems. Discussing the advantages of multilayers, we propose a novel design concept for superconducting electric field-effect transistors based on ferroelectric films.Comment: 5 pages RevTex4, 6 figure

La fundamentación de los derechos humanos: un intento de sistematización

Publicad

Alucinógenos y chamanismo en la tribu Harakmbet.

Sin resume