Energy Level Alignment in Organic-Organic Heterojunctions: The TTF-TCNQ Interface

The energy level alignment of the two organic materials forming the TTF-TCNQ interface is analyzed by means of a local orbital DFT calculation, including an appropriate correction for the transport energy gaps associated with both materials. These energy gaps are determined by a combination of some experimental data and the results of our calculations for the difference between the TTF_{HOMO} and the TCNQ_{LUMO} levels. We find that the interface is metallic, as predicted by recent experiments, due to the overlap (and charge transfer) between the Density of States corresponding to these two levels, indicating that the main mechanism controlling the TTF-TCNQ energy level alignment is the charge transfer between the two materials. We find an induced interface dipole of 0.7 eV in good agreement with the experimental evidence. We have also analyzed the electronic properties of the TTF-TCNQ interface as a function of an external bias voltage \Delta, between the TCNQ and TTF crystals, finding a transition between metallic and insulator behavior for \Delta~0.5 eV

Unemployment and Time Use: Evidence from the Spanish Time Use Survey

In this paper we use a time use approach to analyze the average effect of aggregate unemployment on the daily life of individuals, focusing on the relationship between reduced market work and additional household production of unemployed individuals. Using the Spanish Time Use Survey 2002-2003, we find that, in general, the unemployed devote most of the reduced market time to additional leisure, and only a small proportion of time is devoted to household production activities. However, we find that the relationship between market work and household production with unemployment of individuals depends on regional unemployment rates, since in areas with high unemployment rates reduced market work is made up by additional time spent in household production. Our paper sheds light on the relationship between individuals’ time allocation decisions and aggregate macroeconomic variables.Unemployment, Time Use, Aggregate Unemployment, Enjoyment Data

Continuous time models of interest rate: testing peso-dollar exchange rate.

As an extension of the article by Núñez, De la Cruz and Ortega (2007), different parametric models with jumps are tested with the methodology developed by Ait-Sahalia and Peng (2006), based on the transition function. Data analyzed are the peso-dollar exchange rate. The idea is to implement continuous-time parametric models for the peso-dollar exchange rate. The results confirm that the proposed continuous time models are not good enough to explain the behavior that describes the peso-dollar exchange rate. However, considering some continuous time models with Poisson jumps is possible to describe such behavior.

Tempo-Adjusted Period Parity Progression Measures:

In this paper we apply tempo-adjusted period parity progression ratios (Kohler and Ortega 2002) to Sweden, the Netherlands and Spain. These countries represent three distinct demographic patterns in contemporary Europe and are of particular interest for demographers. The goal of our analyses is to (a) describe past fertility trends in these countries in terms of synthetic cohorts and (b) project the level and distribution of completed fertility in cohorts who have not finished childbearing. Our analyses suggest that the most recent period fertility patterns in these countries do not imply substantial increases in childlessness even in younger cohorts. Moreover, if these patterns prevail in the future, young cohorts would reach completed fertility levels between 1.5-1.75.cohort fertility, fertility, fertility postponement, fertility projection, low fertility, Netherlands, parity progression measures, Spain, Sweden, tempo adjustment

Tempo-Adjusted Period Parity Progression Measures, Fertility Postponement and Completed Cohort Fertility

In this paper we introduce a new set of tempo-adjusted period parity progression measures in order to account for two distinct implications caused by delays in childbearing: tempo distortions imply an underestimation of the quantum of fertility in observed period data, and the fertility aging effect reduces higher parity births because the respective exposure is shifted to older ages when the probability of having another child is quite low. Our measures remove the former distortion and provide means to assess the latter aging effect. The measures therefore provide a unified toolkit of fertility indices that (a) facilitate the description and analysis of past period fertility trends in terms of synthetic cohort measures, and (b) allow the projection of the timing, level and distribution of cohort fertility conditional on a specific postponement scenario. Due to their explicit relation to cohort behavior, these measures extend and improve the existing adjustment of the total fertility rate. We apply these methods to Sweden from 1970 to 1999.cohort fertility, fertility, fertility postponement, fertility projection, low fertility, parity progression, parity progression measures, Sweden, tempo adjustment

Bone loss in implants placed at subcrestal and crestal level: A systematic review and meta-analysis

Background: To assess differences in marginal bone loss in implants placed at subcrestal versus crestal level. Methods: An electronic and a manual research of articles written in English from Jaunary 2010 to January 2018 was performed by two independent reviewers. Clinical trials comparing bone loss for implants placed at crestal and subcrestal level were included. Pooled estimates from comparable studies were analyzed using a continuous random-effects model meta-analysis with the objective of assessing differences in crestal bone loss between the two vertical positions. Results: 16 studies were included; 10 studies did not encounter statistically significant differences between the two groups with respect to bone loss. Three articles found greater bone loss in subcrestal implants; while 3 found more bone loss in crestal implants. A meta-analysis for randomized control trial (RCT) studies reported an average and non-statistically different crestal bone loss of 0.028 mm. Conclusions: A high survival rate and a comparable bone loss was obtained both for crestal and subcrestal implants’ placement. Quantitative analysis considering a homogenous sample confirms that both vertical positions are equally valid in terms of perimplant bone loss. However, with respect to soft tissue; in presence of a thin tissue; a subcrestal placement of the implant should be preferred as it may reduce the probability for the implant to become exposed in the future and thus avoid the risk of suffering from peri-implant pathologies

H2_2 dissociation over Au-nanowires and the fractional conductance quantum

The dissociation of H$_2$ molecules on stretched Au nanowires and its effect on the nanowire conductance are analyzed using a combination of Density Functional (DFT) total energy calculations and non-equilibrium Keldish-Green function methods. Our DFT simulations reproduce the characteristic formation of Au monoatomic chains with a conductance close to % the conductance quantum $G_0 = 2e^2/h$. These stretched Au nanowires are shown to be better catalysts for H$_2$ dissociation than Au surfaces. This is confirmed by the nanowire conductance evidence: while not affected practically by molecular hydrogen, atomic hydrogen induces the appearance of fractional conductances ($G \sim 0.5 G_0$) as observed experimentally.Comment: 4 pages, 3 figure

Space, mass and ornament in the Gothic-Renaissance transition in Spain

La introducción en España de las nuevas formas y sintaxis renacentistas a lo largo del siglo xvi no se produjo con un abandono radical e inmediato de los viejos usos góticos, de validez comprobada en trascendentales cuestiones del diseño arquitectónico. La renovación de la producción fue heterogénea y en cierto modo particular de cada artífice, según su formación previa y el grado de contacto, coherencia y compromiso con las novedades italianas, generando un panorama híbrido y plural en la arquitectura del quinientos hispano. Atendiendo a significativos textos y documentos gráficos de la época, se pretende rastrear los cambios, e inercias, en el proceso de diseño arquitectónico durante esta larga etapa de transición, estructurando el análisis a partir de tres categorías sustanciales, interdependientes y autónomas a la vez: espacio, masa y ornato.During the sixteenth century the new Renaissance forms were introduced in Spain, but the Gothic procedures continued to be used due to their proven validity for the architectural design. The renovation of the architecture was heterogeneous and different for each master, according to his previous training and his knowledge of the new Italian forms. This involved a hybrid and plural context in the Spanish architecture of the 16th century. The changes and continuities of the architectural design process during this transitory stage are investigated in this paper, based on significant texts and graphic documents of this period. The analysis is structured based on three substantial architectural categories, which are simultaneously interdependent and autonomous: space, mass and ornamen

Application of a Natural Language Interface to the Teleoperation of a Mobile Robot

IFAC Intelligent Components for Vehicles, Seville, Spain, 1998This paper describes the application of a natural language interface to the teleoperation of a mobile robot. Natural language communication with robots is a major goal, since it allows for non expert people to communicate with robots in his or her own language. This communication has to be flexible enough to allow the user to control the robot with a minimum knowledge about its details. In order to do this, the user must be able to perform simple operations as well as high level tasks which involve multiple elements of the system. For this ones, an adequate representation of the knowledge about the robot and its environment will allow the creation of a plan of simple actions whose execution will result in the accomplishment of the requested tas