18,498 research outputs found

    Human capital and regional economic growth - Evidence from the dual approach

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    Theoretical contributions to the literature have stressed the role of human capital in promoting economic growth. However, the empirical exercises have provided mixed evidence on the real effect of such type of capital. Most of the evidence has been obtained by estimating growth equations or production functions using samples of (heterogeneous) countries. In this paper, we report empirical evidence on the effects of human capital in the sample of Spanish regions. As they are supposed to be more homogeneous economies from an institutional, social and economic perspective, we assume that the evidence provide in this paper is a more robust measure of the real effects of human capital in stimulating the take off of lagging economies. We departure from the traditional empirical approach as our estimates come from the dual framework. This easily allows us to get not only the aggregate return to human capital, but also some other important measures such as its shadow price, that is the willingness to pay for an extra year of education of firm’s employees, and the degree of complementariety/substitutability with other types of capital. Results suggest that human capital has exerted a significant effect in the Spanish regions, which is stronger in the less developed ones. It not only have a direct effect but an indirect one by compensating the mechanism of decreasing returns to physical capital. Important conclusions for the assessment and design of regional development policies can be derived from such results.

    The value of coskewness in mutual fund performance evaluation.

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    Recent asset pricing studies demonstrate the relevance of incorporating coskewness in asset pricing models, and illustrate how this component helps to explain the time variation of ex-ante market risk premiums. This paper analyzes the role of coskewness in mutual fund performance evaluation and finds evidence that adding a coskewness factor is economically and statistically significant. It documents that coskewness is sometimes managed and shows persistence of the coskewness policy over time. One of the most striking results is that many negative (positive) alpha funds, measured relative to the CAPM risk adjustments, would be reclassified as positive (negative) alpha funds using a model with coskewness. Therefore, performance ranking based on risk-adjusted returns without considering coskewness could generate an erroneous classification. Moreover, some fund characteristics, such as turnover ratio or category, are related to the likelihood of managing coskewness.Coskewness; Mutual funds; Performance measures;

    Ultrafast transient absorption spectroscopy: principles and applications

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    The study of photophysical and photochemical processes crosses the interest of many fields of research in physics, chemistry and biology. In particular, the photophysical and photochemical reactions, after light absorption by a photosynthetic pigment-protein complex, are among the fastest events in biology, taking place on timescales ranging from tens of femtoseconds to a few nanoseconds. Among the experimental approaches developed for this purpose, the advent of ultrafast transient absorption spectroscopy has become a powerful and widely used technique.[1,2] Focusing on the process of photosynthesis, it relies upon the efficient absorption and conversion of the radiant energy from the Sun. Chlorophylls and carotenoids are the main players in the process. Photosynthetic pigments are typically arranged in a highly organized fashion to constitute antennas and reaction centers, supramolecular devices where light harvesting and charge separation take place. The very early steps in the photosynthetic process take place after the absorption of a photon by an antenna system, which harvests light and eventually delivers it to the reaction center. In order to compete with internal conversion, intersystem crossing, and fluorescence, which inevitably lead to energy loss, the energy and electron transfer processes that fix the excited-state energy in photosynthesis must be extremely fast. In order to investigate these events, ultrafast techniques down to a sub-100 fs resolution must be used. In this way, energy migration within the system as well as the formation of new chemical species such as charge-separated states can be tracked in real time. This can be achieved by making use of ultrafast transient absorption spectroscopy. The basic principles of this notable technique, instrumentation, and some recent applications to photosynthetic systems[3] will be described. Acknowledgements M. Moreno Oliva thanks the MINECO for a “Juan de la Cierva-Incorporación” research contract. References [1] U. Megerle, I. Pugliesi, C. Schriever, C.F. Sailer and E. Riedle, Appl. Phys. B, 96, 215 – 231 (2009). [2] R. Berera, R. van Grondelle and J.T.M. Kennis, Photosynth. Res., 101, 105 – 118 (2009). [3] T. Nikkonen, M. Moreno Oliva, A. Kahnt, M. Muuronen, J. Helaja and D.M. Guldi, Chem. Eur. J., 21, 590 – 600 (2015).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Rpd3L and Hda1 histone deacetylases facilitate repair of broken forks by promoting sister chromatid cohesion

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    Genome stability involves accurate replication and DNA repair. Broken replication forks, such as those encountering a nick, lead to double strand breaks (DSBs), which are preferentially repaired by sister-chromatid recombination (SCR). To decipher the role of chromatin in eukaryotic DSB repair, here we analyze a collection of yeast chromatin-modifying mutants using a previously developed system for the molecular analysis of repair of replication-born DSBs by SCR based on a mini-HO site. We confirm the candidates through FLP-based systems based on a mutated version of the FLP flipase that causes nicks on either the leading or lagging DNA strands. We demonstrate that Rpd3L and Hda1 histone deacetylase (HDAC) complexes contribute to the repair of replication-born DSBs by facilitating cohesin loading, with no effect on other types of homology-dependent repair, thus preventing genome instability. We conclude that histone deacetylation favors general sister chromatid cohesion as a necessary step in SCR

    DIFFERENCES IN TOTAL FACTOR PRODUCTIVITY ACROSS FIRM SIZE - A DISTRIBUTIONAL ANALYSIS

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    Productivity has been considered a key element for firms and economies to be more competitive. Several studies on productivity at a microeconomic level have found notable heterogeneity between firms. More concretely, differences in Total Factor Productivity (TFP) between large and small firms have been observed. Those differences might be caused by differences in the distribution of the factors determining the level of TFP across firms’ size, and by differences in the return to such factors. To assess to what extent the observed differences in TFP between large and small Spanish manufacturing firms are caused by the above-mentioned reasons we propose a methodology that, built on the traditional Oaxaca-Blinder decomposition, focuses the attention on the entire distribution of productivity. The TFP index used in our paper guarantees comparison of the level of productivity across firms in a given year and over time, and has been computed using the information in the Encuesta sobre Estrategias Empresariales (ESEE), a comprehensive survey of manufacturing firms in Spain from 1990 to 1999. Results confirm that the distribution of TFP in the large firms dominates that for the small firms, and how besides differences in the distribution of, for example, human capital and R&D expenditures across firms’ size, heterogeneity in returns between large and small firms play a major role in explaining differences in the distribution of TFP. Important policy issue are derived in connection with the possibility of increasing the aggregate productivity of the Spanish economy considering that the average firm size in Spain is smaller than in other European countries.

    New Technique to Enhance the Performance of Spoken Dialogue Systems by Means of Implicit Recovery of ASR Errors

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    This paper proposes a new technique to implicitly correct some ASR errors made by spoken dialogue systems, which is implemented at two levels: statistical and linguistic. The goal of the former level is to employ for the correction knowledge extracted from the analysis of a training corpus comprised of utterances and their corresponding ASR results. The outcome of the analysis is a set of syntactic-semantic models and a set of lexical models, which are optimally selected during the correction. The goal of the correction at the linguistic level is to repair errors not detected during the statistical level which affects the semantics of the sentences. Experiments carried out with a previouslydeveloped spoken dialogue system for the fast food domain indicate that the technique allows enhancing word accuracy, spoken language understanding and task completion by 8.5%, 16.54% and 44.17% absolute, respectively.Ministerio de Ciencia y Tecnología TIN2007-64718 HAD

    Vehicle pose estimation using G-Net: multi-class localization and depth estimation

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    In this paper we present a new network architecture, called G-Net, for 3D pose estimation on RGB images which is trained in a weakly supervised manner. We introduce a two step pipeline based on region-based Convolutional neural networks (CNNs) for feature localization, bounding box refinement based on non-maximum-suppression and depth estimation. The G-Net is able to estimate the depth from single monocular images with a self-tuned loss function. The combination of this predicted depth and the presented two-step localization allows the extraction of the 3D pose of the object. We show in experiments that our method achieves good results compared to other state-of-the-art approaches which are trained in a fully supervised manner.Peer ReviewedPostprint (author's final draft

    Decomposing differences in total factor productivity across firm size

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    This paper investigates the extent to which the gap in total factor productivity between small and large firms is due to differences in the endowment of factors determining productivity and to the returns associated with these factors. We place particular emphasis on the contribution of differences in the propensity to innovate and in the use of skilled labor across firms of different size. Empirical evidence from a representative sample of Spanish manufacturing firms corroborates that both differences in endowments and returns to innovation and skilled labor significantly contribute to the productivity gap between small and large firms. In addition, it is observed that the contribution of innovation to this gap is caused only by differences in quantity, while differences in returns have no effect; in the case of human capital, however, most of the effect can be attributed to increasing differences in returns between small and large firms.Total Factor Productivity; skilled labor; innovation; firm size; Oaxaca decomposition

    Mechanisms of Action and Targets of Nitric Oxide in the Oculomotor System

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    Nitric oxide (NO) production by neurons in the prepositus hypoglossi (PH) nucleus is necessary for the normal performance of eye movements in alert animals. In this study, the mechanism(s) of action of NO in the oculomotor system has been investigated. Spontaneous and vestibularly induced eye movements were recorded in alert cats before and after microinjections in the PH nucleus of drugs affecting the NO–cGMP pathway. The cellular sources and targets of NO were also studied by immunohistochemical detection of neuronal NO synthase (NOS) and NO-sensitive guanylyl cyclase, respectively. Injections of NOS inhibitors produced alterations of eye velocity, but not of eye position, for both spontaneous and vestibularly induced eye movements, suggesting that NO produced by PH neurons is involved in the processing of velocity signals but not in the eye position generation. The effect of neuronal NO is probably exerted on a rich cGMP-producing neuropil dorsal to the nitrergic somas in the PH nucleus. On the other hand, local injections of NO donors or 8-Br-cGMP produced alterations of eye velocity during both spontaneous eye movements and vestibulo-ocular reflex (VOR), as well as changes in eye position generation exclusively during spontaneous eye movements. The target of this additional effect of exogenous NO is probably a well defined group of NO-sensitive cGMP-producing neurons located between the PH and the medial vestibular nuclei. These cells could be involved in the generation of eye position signals during spontaneous eye movements but not during the VOR.Fondo de Investigación Sanitaria Grants 94/0388 and 97/2054Comunidad Autónoma de Madrid Grant 08.5/0019/1997Dirección General de Investigación Científica y Technológica Grant PB 93–117

    On the optimal management of teams under budget constraints

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    We study optimal wage schemes for teams, under the presence of budget constraints, in a model in which agents’ effort decisions are mapped into the probability of the team’s success. We show that (first-best) efficiency can only be attained with complex contracts that are vulnerable to ex post manipulations and off-equilibrium path violations of the budget constraints. Within the domain of simple (and budget-balanced) contracts, an interesting scheme, which treats equal members of the team unequally, emerges as optimalTeam production, budget constraints, efficiency, manipulability, impartiality
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