715 research outputs found

    Suppressors of selection

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    Inspired by recent works on evolutionary graph theory, an area of growing interest in mathematical and computational biology, we present the first known examples of undirected structures acting as suppressors of selection for any fitness value r>1r > 1. This means that the average fixation probability of an advantageous mutant or invader individual placed at some node is strictly less than that of this individual placed in a well-mixed population. This leads the way to study more robust structures less prone to invasion, contrary to what happens with the amplifiers of selection where the fixation probability is increased on average for advantageous invader individuals. A few families of amplifiers are known, although some effort was required to prove it. Here, we use computer aided techniques to find an exact analytical expression of the fixation probability for some graphs of small order (equal to 66, 88 and 1010) proving that selection is effectively reduced for r>1r > 1. Some numerical experiments using Monte Carlo methods are also performed for larger graphs.Comment: New title, improved presentation, and further examples. Supporting Information is also include

    La contribución de las energías renovables al desarrollo rural sostenible en la Unión Europea: pautas teóricas para el análisis empírico

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    Ejemplar dedicado a: Marx, Keynes y SchumpeterEl marco en el que se desenvuelve actualmente el sector agrario europeo sit√ļa al mundo rural en una encrucijada en la que su propia supervivencia como espacio de reproducci√≥n social y econ√≥mica depender√° en buena parte de las funciones social y ambiental de una agricultura abocada a ser multifuncional y del √©xito de las pol√≠ticas del segundo pilar de la PAC, a la saz√≥n denominado Desarrollo Rural. En ese contexto, cobra una gran relevancia la funci√≥n del mundo rural como espacio proveedor de energ√≠as renovables. El presente art√≠culo se centra en esta nueva realidad y pretende, ante la escasez de estudios que de forma emp√≠rica analicen la contribuci√≥n de la producci√≥n de energ√≠as renovables al desarrollo rural sostenible, dar unas pautas te√≥ricas que de forma sistem√°tica y gen√©rica permitan llevar a cabo estudios emp√≠ricos que contrasten el papel que las energ√≠as renovables pueden jugar en el mundo rural.Peer reviewe

    A methodology to improve simulation of multibody systems using estimation techniques

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    This paper presents a methodology for state estimation and accuracy improvement of computer simulations of computer aided engineering (CAE) models based on prediction and correction state estimation techniques and sensing. The aim is to simulate the dynamic behaviour of a real system, which can be sensed, and obtain values of states that are not measurable due to economic or technical limitations. This methodology can be applied to both optimization of design processes and on-line control of complex systems. State estimation techniques are currently used only on mathematical models, where the relationships among system variables are expressed by means of mathematical language, making state observer implementation possible but leading to limitations in system modelling and knowledge. Favoured over mathematical models, multibody CAE models (created by means of computer-aided engineering software) have become the essential tool for complex system development, simulation, analysis, optimization and control, such as multibody systems; one of their main advantages is the ease and flexibility in creating and modifying them, allowing the faithful modelling of complex systems

    Exploring the Crystal Structure Space of CoFe2P by Using Adaptive Genetic Algorithm Methods

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    Advances in theoretical and computational condensed matter physics have opened the possibility to predict and design magnetic materials for specific technological applications. In this paper, we use the adaptive-genetic algorithm technique for exploring the low-energy crystal structure configurations of Co0.25Fe0.5P0.25, aiming to find new low-energy non-cubic phases with high saturation magnetization that might be interesting for high-performance permanent magnet development.This work was supported in part by the NOVAMAG project under Grant 686056, in part by the EU Horizon 2020 Framework Program for Research and Innovation (2014‚Äď2020), and in part by the Spanish Supercomputing Network and CESVIMA for providing computational resources under Grant QCM-2016-2-0034

    Sustainability and the Central Maghrib Economies.

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    Recent scientific analysis has clearly underlined the fact that human beings face the difficult challenge of satisfying their economic needs without significantly altering the basic functions of the biosphere. Survival depends on satisfying those needs while simultaneously respecting ecological functionality such that a balance between the level of economic activity and environmental protection must be established. This challenge is probably greater in Southern countries than in industrialised ones, given that, in the former countries, human needs are far from being satisfied in an optimal manner. The purpose of this article is to examine the social, environmental and economic conditions facing Central Maghrib countries in the context of the risks they face regarding this sustainability challenge. In this sense, both because of its weak socio-economic and natural conditions, the Maghrib is one the regions of the earth where this challenge is most evident

    A high-throughput exploration of magnetic materials by using structure predicting methods

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    We study the capability of a structure predicting method based on genetic/evolutionary algorithm for a high-throughput exploration of magnetic materials. We use the USPEX and VASP codes to predict stable and generate low-energy meta-stable structures for a set of representative magnetic structures comprising intermetallic alloys, oxides, interstitial compounds, and systems containing rare-earths elements, and for both types of ferromagnetic and antiferromagnetic ordering. We have modified the interface between USPEX and VASP codes to improve the performance of structural optimization as well as to perform calculations in a high-throughput manner. We show that exploring the structure phase space with a structure predicting technique reveals large sets of low-energy metastable structures, which not only improve currently exiting databases, but also may provide understanding and solutions to stabilize and synthesize magnetic materials suitable for permanent magnet applications.EU H2020 Program Project NOVAMAG: Novel, critical materials free, high anisotropy phases for permanent magnets, by design (Project ID: 686056)

    An adaptive genetic algorithm approach for predicting magnet-ic structure suitable for high-performance permanent magnet development

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    Trabajo presentado en: International Conference on Magnetics (INTERMAG), 2017Summary form only given. In this work, we present a general overview, analysis and software implementation of a particular AGA, which has been proposed for discovering new RE-free magnetic crystal phases in the context of the EU-H2020 NOVAMAG project. The workflow diagram related to the Modelling Data Elements (MODA) of the magnetic crystal structure calculation based on AGA was shown. In particular, we make use of an AGA, implemented through USPEX and VASP codes, to predict new magnetic crystal phases, where those structures with better magnetic properties for a permanent magnet are selected and analyzed in more detail. Such a methodology has been preliminary compared to well-known experimentally reported properties compounds, showing an excellent agreement. In addition, we show recent results predicted by AGA in CoFe 2n X (n=1,2,3,4,5; where X=C, P, Hf, Zr, ...), where we found compounds with many metastable structures which fulfill the initial requirements (negative enthalpy of formation őĒHF1T and non-cubic lattice system) for permanent magnet development.NOVAMAG project, under Grant Agreement No. 686056, EU Horizon 2020 Framework Programme for Research and Innovation (2014-2020). Authors also acknowledge the Spanish Supercomputing Network (RES) and CESVIMA for providing supercomputational resources under Ref: QCM-2016-2-0034

    Assesing the impact of renewable energy deployment on local sustainability: Towards a theoretical framework

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    Renewable energy sources (RES) have a large potential to contribute to the sustainable development (SD) of specific territories by providing them with a wide variety of socioeconomic and environmental benefits. However, the existing literature has put much emphasis on the environmental benefits (including the reduction of global and local pollutants), while socioeconomic impacts have not received a comparable attention. These include diversification of energy supply, enhanced regional and rural development opportunities, creation of a domestic industry and employment opportunities. With the exception of the diversification and security of energy supply, these benefits have usually been mentioned, but their analysis has been too general (i.e., mostly at the national level) and a focus on the regional and, even more so, the local level, has been lacking. At most, studies provide scattered evidence of some of those regional and local benefits, but without an integrated conceptual framework to analyse them. This paper tries to make a contribution in this regard by developing an integrated theoretical framework which allows a comprehensive analysis of the impact of renewable energy on local sustainability and which can be empirically applied to identify these benefits indifferent territories

    Slow pyrolysis of Cortaderia Selloana using response surface methodology

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