24,805 research outputs found

    Residual effect of natural and synthetic zinc chelates on zinc in a soil solution of a waterlogged acidic soil. Evolution of the pH and redox potential.

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    Zinc chelates have been widely used to correct deïŹciencies in this micronutrient in different soil types and under different moisture conditions. The aging of the metal in soil could cause a change in its availability. Over time the most labile forms of Zn could decrease in activity and extractability and change to more stable forms. Various soil parameters, such as redox conditions, time, soil type and moisture conditions, affect the aging process and modify the solubility of the metal. In general, redox conditions inïŹ‚uence pH and also the chemical forms dissolved in the soil solution. Soil pH also affects Zn solubility; at high pH values, most of the Zn is present in forms that are not bioavailable to plants. The objective of this study was to determine the changes in Zn over time in a soil solution in a waterlogged acidic soil to which synthetic and natural chelates were applie

    Hitchin-Kobayashi correspondence, quivers, and vortices

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    A twisted quiver bundle is a set of holomorphic vector bundles over a complex manifold, labelled by the vertices of a quiver, linked by a set of morphisms twisted by a fixed collection of holomorphic vector bundles, labelled by the arrows. When the manifold is Kaelher, quiver bundles admit natural gauge-theoretic equations, which unify many known equations for bundles with extra structure. In this paper we prove a Hitchin--Kobayashi correspondence for twisted quiver bundles over a compact Kaehler manifold, relating the existence of solutions to the gauge equations to a stability criterion, and consider its application to a number of situations related to Higgs bundles and dimensional reductions of the Hermitian--Einstein equations.Comment: 28 pages; larger introduction, added references for the introduction, added a short comment in Section 1, typos corrected, accepted in Comm. Math. Phy

    Deep neural network for traffic sign recognition systems: An analysis of spatial transformers and stochastic optimisation methods

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    This paper presents a Deep Learning approach for traffic sign recognition systems. Several classification experiments are conducted over publicly available traffic sign datasets from Germany and Belgium using a Deep Neural Network which comprises Convolutional layers and Spatial Transformer Networks. Such trials are built to measure the impact of diverse factors with the end goal of designing a Convolutional Neural Network that can improve the state-of-the-art of traffic sign classification task. First, different adaptive and non-adaptive stochastic gradient descent optimisation algorithms such as SGD, SGD-Nesterov, RMSprop and Adam are evaluated. Subsequently, multiple combinations of Spatial Transformer Networks placed at distinct positions within the main neural network are analysed. The recognition rate of the proposed Convolutional Neural Network reports an accuracy of 99.71% in the German Traffic Sign Recognition Benchmark, outperforming previous state-of-the-art methods and also being more efficient in terms of memory requirements.Ministerio de EconomĂ­a y Competitividad TIN2017-82113-C2-1-RMinisterio de EconomĂ­a y Competitividad TIN2013-46801-C4-1-

    Financial Globalization and Labor: Employee Shareholding or Labor Regression?

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    The authors review from a critical perspective the ‘patrimonial capitalism’ approach, as well as its analysis of wage-labor transformations in developed economies during the last thirty years. For this purpose, they take the economies of France and the United States as study cases. According to this approach, patrimonial financialization of working households has involved a radical transformation of the wage-labor nexus, paradigmatically exemplified by the concept of employee shareholding. The authors point out weaknesses of this approach, theoretical as well as empirical. Furthermore, they focus on an alternative interpretation that characterizes the nature of wage-labor nexus transformation in the French and U.S. economies as a wage adjustment. This wage adjustment is the result of the neoliberal policies developed to restore capital profitability after the crisis of the 1970s, and has caused an erosion of salary and social conquests attained by labor after the Second World War. Finances have acted as a lever of social reorganization among classes to achieve the objective of profitability recovery.patrimonial capitalism, financial globalization, employee shareholding, crisis, wage adjustment, USA, France

    Effective and neutral stresses in soils using boundary element methods

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    The evaluation of neutral pressures in soil mechanics problems is a fundamental step to evaluate deformations in soils. In this paper, we present some results obtained by using the boundary element method for plane problems, describing the undrained situation as well as the consolidation problem

    Foundations and social economy: conceptual approaches and socio-economic relevance

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    Theoretical debate about the nature of charitable foundations has traditionally become polarized around two distinct conceptual approaches: the non-profit or third sector approach, versus the social economy approach. This research tries to find a common ground between these two approaches, and to highlight the specificities of the foundation as an organizational formula, supporting its current socio-economic relevance with latest quantitative data on the contemporary Spanish foundation sector. In order to achieve this purpose, data from the main empirical studies about the sector during the last decade are compared, with a special focus on those obtained by the recently constituted Institute for Strategic Analysis of Foundations (INAEF).Foundations, social economy, non-profit organizations, third sector, socioeconomic impact, INAEF.

    The personal income tax applied in the member states of European Union. The case of Spain.

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    In the Communication on "Tax policy in the European Union - Priorities for the years ahead" (COM/2001/260 of 23 May 2001), the Commission reiterated its belief that there is no need for an across the board harmonisation of Member States' direct tax systems. For tax policy, the Communication established, as a main priority, the need to address the concerns of individuals and businesses operating within the Internal Market by focusing on the elimination of tax obstacles to all forms of cross-border economic activity, in addition to continuing the fight against harmful tax competition. This approach was confirmed in the Communication "The contribution of taxation and customs policies to the Lisbon strategy" (COM/2005/532 of 25 October 2005) (European Commission, 2006). The Spanish Law No 35/2006, 28 th November of Personal Income Tax, reformed that tax. The long-term capital gains will be taxed at 18% (before 15%) ;the tax scale will be comprised of only 3 or 4 brackets (before 5) and the top marginal rate (before 45%) will be reduced; and some tax credits and allowances (acquisition of permanent home and contributions to pension funds for example) were readjusted in order to make them more accessible to low-income earners. The present paper makes a brief approach to the harmonisation in the European Union, explains the reform of the Spanish Personal Income Tax, introduces new figures and formulas never seen before at book of taxes, analyses the concept of the Spanish Personal Income Tax, studies the elements of this tax as the beneficiary, taxable person, territoriality, basis of assessment, exemptions, explains the basic mechanism of the tax, deductions, the taxable base, the tax rates, collections and examples. This paper is the result of three researches that the authors are carrying out at The Institute for Fiscal Studies, Ministry of Economy and Finance, University of CEU San Pablo, Madrid and University of Oviedo Spain from 2006 to 2008

    Transformational Leadership, Task-Involving Climate, and Their Implications in Male Junior Soccer Players: A Multilevel Approach

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    Despite the well-known positive consequences of transformational coaches in sport, there is still little research exploring the mechanisms through which coaches’ transformational leadership exerts its impact on athletes. Multilevel SEM was used to examine the relationship between coaches’ transformational leadership style, a task-involving climate, and leadership effectiveness outcome criteria (i.e., players’ extra effort, coach effectiveness, and satisfaction with their coach), separately estimating between and within effects. A representative sample of 625 Spanish male soccer players ranging from 16 to 18 years old and nested in 50 teams completed a questionnaire package tapping the variables of interest. Results confirmed that at the team level, team perceptions of transformational leadership positively predicted teams’ perceptions of task climate, which in turn positively predicted the three outcome criteria. At the individual level, players’ perceptions of transformational leadership positively predicted teams’ perceptions of task climate, which in turn positively predicted teams’ extra effort and coach effectiveness. Mediation effects appeared at the team level for all the outcome criteria, and at the individual only for extra effort. Transformational leadership is recommended to enhance task climate, in order to increase players’ extra effort, their perceptions of the effectiveness of their coach, and their satisfaction with his/her leadership style
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