Non-equilibrium transport response from equilibrium transport theory

We propose a simple scheme that describes accurately essential non-equilibrium effects in nanoscale electronics devices using equilibrium transport theory. The scheme, which is based on the alignment and dealignment of the junction molecular orbitals with the shifted Fermi levels of the electrodes, simplifies drastically the calculation of current-voltage characteristics compared to typical non-equilibrium algorithms. We probe that the scheme captures a number of non-trivial transport phenomena such as the negative differential resistance and rectification effects. It applies to those atomic-scale junctions whose relevant states for transport are spatially placed on the contact atoms or near the electrodes.Comment: 5 pages, 4 figures. Accepted in Physical Review

Structure and electronic properties of molybdenum monoatomic wires encapsulated in carbon nanotubes

Monoatomic chains of molybdenum encapsulated in single walled carbon nanotubes of different chiralities are investigated using density functional theory. We determine the optimal size of the carbon nanotube for encapsulating a single atomic wire, as well as the most stable atomic arrangement adopted by the wire. We also study the transport properties in the ballistic regime by computing the transmission coefficients and tracing them back to electronic conduction channels of the wire and the host. We predict that carbon nanotubes of appropriate radii encapsulating a Mo wire have metallic behavior, even if both the nanotube and the wire are insulators. Therefore, encapsulating Mo wires in CNT is a way to create conductive quasi one-dimensional hybrid nanostructures.Comment: 8 pages, 10 figure

Impact of dimerization and stretching on the transport properties of molybdenum atomic wires

We study the electrical and transport properties of monoatomic Mo wires with different structural characteristics. We consider first periodic wires with inter-atomic distances ranging between the dimerized wire to that formed by equidistant atoms. We find that the dimerized case has a gap in the electronic structure which makes it insulating, as opposed to the equidistant or near-equidistant cases which are metallic. We also simulate two conducting one-dimensional Mo electrodes separated by a scattering region which contains a number of dimers between 1 and 6. The $I-V$ characteristics strongly depend on the number of dimers and vary from ohmic to tunneling, with the presence of different gaps. We also find that stretched chains are ferromagnetic.Comment: 8 pages, 7 figure

A multivariate generalized independent factor GARCH model with an application to financial stock returns

We propose a new multivariate factor GARCH model, the GICA-GARCH model , where the data are assumed to be generated by a set of independent components (ICs). This model applies independent component analysis (ICA) to search the conditionally heteroskedastic latent factors. We will use two ICA approaches to estimate the ICs. The first one estimates the components maximizing their non-gaussianity, and the second one exploits the temporal structure of the data. After estimating the ICs, we fit an univariate GARCH model to the volatility of each IC. Thus, the GICA-GARCH reduces the complexity to estimate a multivariate GARCH model by transforming it into a small number of univariate volatility models. We report some simulation experiments to show the ability of ICA to discover leading factors in a multivariate vector of financial data. An empirical application to the Madrid stock market will be presented, where we compare the forecasting accuracy of the GICA-GARCH model versus the orthogonal GARCH one

Impact of Fano and Breit-Wigner resonances in the thermoelectric properties of nanoscale junctions

We show that the thermoelectric properties of nanoscale junctions featuring states near the Fermi level strongly depend on the type of resonance generated by such states, which can be either Fano or Breit-Wigner-like. We give general expressions for the thermoelectric coefficients generated by the two types of resonances and calculate the thermoelectric properties of these systems, which encompass most nanoelectronics junctions. We include simulations of real junctions where metalloporphyrin molecules bridge gold electrodes and prove that for some metallic elements the thermoelectric properties show a large variability. We find that the thermopower and figure of merit are largely enhanced when the resonance gets close to the Fermi level and reach values much higher than typical values found in other nanoscale junctions. The specific value and temperature dependence are determined by a series of factors such as the strength of the coupling between the state and other molecular states, the symmetry of the state, the strength of the coupling between the molecule and the leads and the spin filtering behavior of the junction.Comment: 9 pages, 11 figure

An IMS-Learning Design Editor for a Higher Education Blended Learning Scenario

The IMS-Learning Design has been developed to support the creation of reusable and pedagogically neutral learning scenarios and content. Although it is especially suitable for eLearning, there is a lot of interest on using it in higher education blended learning scenarios. However there are some related key issues which must be managed such as cultural bias and the need for expensive human resources to design and develop specification compliant units of learning. They can be addressed by the design of ad-hoc editors supporting concrete learning design units of learning. We suggest some solutions to overcome these limitations, based on our experience designing the user interface of an IMS-LD compliant editor, GDUS+. We also explain our user centering approach, and give some conclusions about the benefits of using IMS-LD

Development and initial validation of a scale to measure store personality

La reproducción de cada DOCFRADIS para fines educativos y no comerciales está permitida siempre y cuando se cite como fuente a la colección de Documentos de Trabajo de la Cátedra Fundación Ramón Areces de Distribución Comercial (DOCFRADIS)La personalidad de tienda es importante para seleccionar la mejor estrategia de marketing. El papel estratégico de estas características simbólicas, rasgos humanos, que pueden ser atribuidas a las tiendas ha quedado empíricamente demostrado en lo que se refiere a satisfacción percibida de los clientes (Chun y Davies, 2006), así como al comportamiento leal hacia el establecimiento (Zentes, Morschett y Schramm-Klein, 2008). A pesar de la reconocida relevancia del problema, actualmente no disponemos de un instrumento para medir este constructo. Este trabajo describe la investigación inicial llevada a cabo para desarrollar una escala para medir la personalidad de los establecimientos comerciales.It is well known that the personality of a store is important to select the best marketing strategy. The strategic role of these symbolic, humanlike attributes that can be attributed to stores has been empirically demostrated, with respect to customer satisfaction and perceived retail differentiation (Chun & Davies, 2006) as well as with respect to store patronage and loyalty behavior (Zentes, Morschett y Schramm-Klein, 2008). Despite the well-known relevance of the problem we do not currently possess a validated instrument to measure this construct. This paper describes the initial investigation carried out to develop a scale for measuring store personality

A Note on the Pseudo-Spectra and the Pseudo-Covariance Generating Functions of ARMA Processes

Although the spectral analysis of stationary stochastic processes has solid mathematical foundations, this is not the case for non-stationary stochastic processes. In this paper, the algebraic foundations of the spectral analysis of non-stationary ARMA processes are established. For this purpose the Fourier Transform is extended to the field of fractions of polynomials. Then, the Extended Fourier Transform pair pseudo-covariance generating function / pseudo-spectrum, analogous to the Fourier Transform pair covariance generating function / spectrum,is defined. The new transform pair is well defined for stationary and non-stationary ARMA processes. This new approach can be viewed as an extension of the classical spectral analysis. It is shown that the frequency domain has some additional algebraic advantages over the time domain.

Anàlisi crítica dels topoi en el discurs polític: la representació de l’estructura de l’Estat a les Corts Valencianes

XXI Jornades de Foment de la Investigació de la Facultat de Ciències Humanes i Socials (Any 2016)En aquest estudi analitzem les manifestacions ideològiques en els discursos d’investidura referents a l’estructura política Estatal. Concretament, analitzem com es difon la ideologia per mitjà de tries lingüístiques emprades de manera manipulativa pels representants de cada grup parlamentari. L’estudi mostra a la societat l’instrumentari lingüístic emprat per manipular els discursos. L’objectiu d’aquest és demostrar que, a partir de les tries lingüístiques, la ideologia de cada grup parlamentari coneix una representació determinada de l’espai social i les possibilitats de projecció futura al llarg dels discursos d’investidura. Per aconseguir justificar el nostre objectiu, hem definit preguntes de recerca que plantegen el següent: quins topoi incorporen l’imaginari col·lectiu que manifesta la idea de submissió a estructures estatals en els discursos parlamentaris? Hi ha discursos que entenen la Comunitat Valenciana com un espai polític propi? Quins topoi transmeten aquesta idea? Aquestes preguntes fomenten la nostra hipòtesi, la qual exposa que, quan l’orador és d’un partit d’ideologia conservadora, els topoi referits a la Comunitat Valenciana, presents en els discursos d’investidura de les Corts Valencianes, mostren submissió a l’estructura estatal, mentre que, quan l’orador pertany a un partit progressista, aquesta submissió no és present. Per demostrar aquesta hipòtesi hem delimitat el nostre corpus als discursos d’investidura compresos entre la Legislatura I (1983) i la Legislatura IX (2015). Per a l’anàlisi d’aquest textos hem seguit els fonaments teòrics de l’anàlisi crítica del discurs i ens hem basat en l’anàlisi de topoi. A partir de la delimitació de dos topoi referits a la hipòtesi plantejada, hem buscat quines eren les tries lingüístiques que feien referència a cada topos i hem establert un model d’anàlisi agrupant aquests elements lingüístics en etiquetes. A partir d’aquest model hem codificat els textos per obtenir-ne dades rigoroses