61,403 research outputs found

    Do Quasi-Hyperbolic Preferences Explain Academic Procrastination? An Empirical Evaluation

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    Traditional neoclassical thought fails to explain questions such as problems of self-control. Behavioural economics have explained these matters on the basis of the intertemporal preferences of individuals and, specifically, the so-called (β, δ) model which emphasises present bias. This opens the way to the analysis of new situations in which people can adopt incorrect indecisions that make it necessary for the government to intervene. The literature which has developed the (β, δ) model and its implications has generated a categorisation of people that is widely used but which lacks a systematic empirical evaluation. It is important to value the need for this public action. In this article, we develop a method which makes it possible to verify the main implications that this model has to explain the procrastination of university students. Using an experimental time discount task with real monetary incentives, we estimate the students’ β and δ parameters and we analyse their correlation with their answers to a series of questions concerning how they plan to study for an exam. The results are ambiguous given that they back some of the model’s conclusions but reject others, including a number of the most basic ones, such as the relation between present biases and some of the categories of people, these being essential to predict their behaviour

    Tracking-Based Non-Parametric Background-Foreground Classification in a Chromaticity-Gradient Space

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    This work presents a novel background-foreground classification technique based on adaptive non-parametric kernel estimation in a color-gradient space of components. By combining normalized color components with their gradients, shadows are efficiently suppressed from the results, while the luminance information in the moving objects is preserved. Moreover, a fast multi-region iterative tracking strategy applied over previously detected foreground regions allows to construct a robust foreground modeling, which combined with the background model increases noticeably the quality in the detections. The proposed strategy has been applied to different kind of sequences, obtaining satisfactory results in complex situations such as those given by dynamic backgrounds, illumination changes, shadows and multiple moving objects

    Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds

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    Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.The Spanish MICINN (Project CTQ2015-70724-R)University of Sevill

    Real-time shot detection based on motion analysis and multiple low-level techniques

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    To index, search, browse and retrieve relevant material, indexes describing the video content are required. Here, a new and fast strategy which allows detecting abrupt and gradual transitions is proposed. A pixel-based analysis is applied to detect abrupt transitions and, in parallel, an edge-based analysis is used to detect gradual transitions. Both analysis are reinforced with a motion analysis in a second step, which significantly simplifies the threshold selection problem while preserving the computational requirements. The main advantage of the proposed system is its ability to work in real time and the experimental results show high recall and precision values

    Cp2TiCl/D2O/Mn, a formidable reagent for the deuteration of organic compounds

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    Cp2TiCl/D2O/Mn is an efficient combination, sustainable and cheap reagent that mediates the D-atom transfer from D2O to different functional groups and can contribute to the synthesis of new deuterated organic compounds under friendly experimental conditions and with great economic advantages.The Spanish MICINN (Project CTQ2015-70724-R)University of Sevill

    Innovation and jobs: evidence from manufacturing firms

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    This paper is aimed at structurally assessing the employment effects of the innovative activities of firms. We estimate firm level displacement and compensation effects in a model in which the stock of knowledge capital raises firm relative efficiency through process innovations and firm demand through product innovations. Displacement is estimated from the elasticity of employment with respect to innovation in the (conditional or Hicksian) demand for labour. Compensation effects are estimated from a firm-specific demand relationship. We also assess the enlargement and weakening of these effects due to firm agents’ behaviour aimed at appropriating innovation rents. We find that the potential employment compensation effect of process innovations surpasses the displacement effect, both in the short and long run (when competitors react), and that product innovation doubles the expanding impact by unit of expenditure, but also that agents’ behaviour can seriously reduce these effects. The actual elasticity of employment to knowledge capital is estimated, however, not far from unity, while “passive” productivity growth is suggested to have null or negative employment effects

    Non-ergodic states induced by impurity levels in quantum spin chains

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    The semi-infinite XY spin chain with an impurity at the boundary has been chosen as a prototype of interacting many-body systems to test for non-ergodic behavior. The model is exactly solvable in analytic way in the thermodynamic limit, where energy eigenstates and the spectrum are obtained in closed form. In addition of a continuous band, localized states may split off from the continuum, for some values of the impurity parameters. In the next step, after the preparation of an arbitrary non-equilibrium state, we observe the time evolution of the site magnetization. Relaxation properties are described by the long-time behavior, which is estimated using the stationary phase method. Absence of localized states defines an ergodic region in parameter space, where the system relaxes to a homogeneous magnetization. Out of this region, impurity levels split from the band, and localization phenomena may lead to non-ergodicity.Comment: 10 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1703.0344

    Experimental study of MIMO-OFDM transmissions at 94 GHz in indoor environments

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    Millimeter wave (mm-wave) frequencies have been proposed to achieve high capacity in 5G communications. Although meaningful research on the channel characteristics has been performed in the 28, 38and 60 GHz bands ─in both indoor and short-range scenarios─,only a small number of trials (experiments) have been carried out in other mm-wave bands. The objective of this work is to study the viability and evaluate the performance of the 94 GHz frequency band for MIMO-OFDM transmission in an indoor environment. Starting from a measurement campaign, the performance of MIMO algorithms is studied in terms of throughput for four different antenna configurations.This work was supported in part by the Ministerio de Economía y Competitividad MINECO, Spain under Grant TEC2016-78028-C3-2-P, and in part by the European FEDER funds

    Biochemical evidence of chromosome homoeology among related plant genera.

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    Biochemical markers associated with homoelogous chromosome groups 3 and 7 of Triticum aestivum L. have been investigated in genetic stocks carrying chromosomes or chromosomal segments of the same homoeology groups from Agropyron elongatum and Secale cereale. Chromosomes 3Ag of Agropyron and 3R of Secale control proteins a3 and b3 with the same properties as proteins 5, 6 and 7 associated with 3B and 3D of Triticum. It is concluded that genes for proteins 5, a3 and b3 are located in segments proximal to the centromere in the β arms of chromosomes 3D and 3Ag, respectively. Proteins 3, 4 and 11, controlled by 7D-short arm of Triticum, are replaced by proteins a7, b7 and c7, when that chromosome is replaced by 7 Ag. Genes for these proteins are located proximal to the centromere in the short arms of chromosomes 7D and 7 Ag. Finally, a gene that controls sterol esterification is similarly located in the short arms of chromosomes 7D and 7 A
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