2,835 research outputs found

    Quantitative LEED analysis using a simultaneous optimisation algorithm

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    The performance of a combinatorial simultaneous optimisation algorithm (SO) is tested using experimental LEED I(E) data from Cu(100) and Fe0.57_{0.57}Al0.47_{0.47}(100) surfaces. SO optimises structures taking advantage of the experimental database at two levels: (i) conmensurate subsets of the database with the number of unknown parameters are chosen to find local solutions using Broyden's method and, (ii) these partial structural solutions are used to build a Markov chain over the whole database. This procedure is of global character, the same as simulated annealing or genetic algorithms methods, but displays a very competitive scaling law because after the first iteration candidates are not chosen by a blind/random pick; they are already solutions to the problem with a restricted experimental database.Financed by CYCIT (MAT-2005-3866) and MEC (CONSOLIDER NANOSELEC-26400

    Kinematic, strength, and stiffness adaptations after a short-term sled towing training in athletes

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    One of the most frequently used methods for training the sprint‐specific strength is the sled towing. To date, no studies have been conducted to explore the effects of this method after a training period in well‐trained athletes. The purpose of this study was to determine the effects of 4 weeks of resisted sprint training with sled towing. Twenty‐two trained athletes experienced in the use of weighted sled (WS) participated in the study. They conducted the same 3‐week training to level their initial condition. After that they were distributed in two groups, unresisted (UR) and WS training. They carried out the same 4‐week, 2 days/week sprint‐specific training, only differing in that the experimental group performed sprints with a (WS) which caused a reduction of 7.5% of their maximum velocity. Pre‐ and posttest were conducted which included the measurement of sprint kinematics, muscular strength (including isoinertial, isokinetic, and jump measurements), and sprinting stiffness (leg and vertical). Results show different adaptations in the groups although no interaction effect was found. The WS group improved the velocity in the transition phase, while the UR group improved the velocity in the maximum velocity phase. No improvements in the height of the jump tests were found.Actividad Física y Deport

    Zero permeability and zero permittivity band gaps in 1D metamaterial photonic crystals

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    We consider layered heterostructures combining ordinary positive index materials and dispersive metamaterials. We show that these structures can exhibit a new type of photonic gap around frequencies where either the magnetic permeability \mu or the electric permittivity \epsilon of the metamaterial is zero. Although the interface of a semi-infinite medium with zero refractive index (a condition attained either when \mu= 0 or when \epsilon= 0) is known to give full reflectivity for all incident polarizations, here we show that a gap corresponding to \mu = 0 occurs only for TE polarized waves, whereas a gap corresponding to \epsilon = 0 occurs only for TM polarized waves. These band gaps are scale-length invariant and very robust against disorder, although they may disappear for the particular case of propagation along the stratification direction.Comment: 7 pages, 5 figure

    Fiber sensors for the high-speed railway environment

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    Specialty Optical Fibers 2014, Barcelona, Spain, 27–31 July 2014We review some recent work on fiber-optic sensors for the high-speed railway environment. In particular, we show convenient fiber-optic solutions for rail and wheel monitoring, perimeter security and catenary protection in changeover section

    A novel modular voltage balancing topology for active battery management system

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    This paper proposes a novel modular voltage balancing topology for an active battery management system (BMS). The proposed topology consists of two power stages. The first stage is composed by a switch network, which is responsible for selecting the battery that will provide energy and the battery that will receive energy. In the switch network, for each battery, are used two cells, which allow the operation with bidirectional current flow and bipolar voltage. The second stage is composed by a capacitor used as energy storage element, which consists in the component used to link both batteries. The switch network control and its interaction with the energy storage element is performed by a digital controller. The paper presents the main computer simulations, as well as the main experimental results obtained to validate the proposed voltage balancing topology for an active BMS.This work has been supported by FCT - Fundação para a Ciência e Tecnologia in the scope of the project: PEst-UID/CEC/00319/2013. Mr. Vítor Monteiro was supported by the doctoral scholarship SFRH/BD/80155/2011 granted by the FCT agency

    Characteristics and effects of resisted sprint training methods

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    Para la mejora del rendimiento en el sprint se utilizan distintos métodos de entrenamiento, entre los más populares se encuentran los métodos resistidos. Un método resistido para el sprint se caracteriza por utilizar sprints con una sobrecarga o resistencia añadida. Dependiendo de las características del dispositivo, tanto la magnitud como la dirección de la resistencia va a ser diferente. Así, existen distintos tipos de métodos resistidos, estos son: arrastres de trineos o ruedas, lastres de chalecos o cinturones, arrastres de paracaídas, carreras cuesta arriba, e incluso carreras sobre la arena de la playa. El principal objetivo al usar métodos resistidos es mejorar la fuerza específica de los deportistas sin producir una modificación significativa de la técnica del deportista. En el presente trabajo se revisan las características y efectos de los métodos resistidos tanto de forma aguda, como sus efectos a corto, medio y largo plazo.Actividad Física y Deport

    143 PRINCIPAL COMPONENT CLUSTERING OF FRONTAL PLANE KNEE KINEMATICS

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    Replication forks stall at different DNA obstacles such as those originated by transcription. Fork stalling can lead to DNA double-strand breaks (DSBs) that will be preferentially repaired by homologous recombination when the sister chromatid is available. The Rrm3 helicase is a replisome component that promotes replication upon fork stalling, accumulates at highly transcribed regions and prevents not only transcription-induced replication fork stalling but also transcription-associated hyper-recombination. This led us to explore the possible role of Rrm3 in the repair of DSBs when originating at the passage of the replication fork. Using a mini-HO system that induces mainly single-stranded DNA breaks, we show that rrm3Δ cells are defective in DSB repair. The defect is clearly seen in sister chromatid recombination, the major repair pathway of replication-born DSBs. Our results indicate that Rrm3 recruitment to replication-born DSBs is crucial for viability, uncovering a new role for Rrm3 in the repair of broken replication forks.This work was supported by grants from the Spanish Ministry of Economy and Innovation (BFU2013-42918), the European Union (FEDER), the European Research Council (ERC2014 AdG669898 TARLOOP), and the Junta de Andalucía (BIO1238). SMG was funded by a predoctoral training fellowship from the Spanish National Research Council (CSIC) and BGG by a postdoctoral grant from the Scientific Foundation of the Spanish Association Against Cancer (AECC). Funding for open access charge: Grants from the Spanish Ministry of Economy and Innovation (BFU2013-42918).Peer Reviewe

    Beef from Calves Finished with a Diet Based on Concentrate Rich in Agro-Industrial By-Products: Acceptability and Quality Label Preferences in Spanish Meat Consumers

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    Conjoint analysis was used to estimate the relative importance of some of the main extrinsic attributes and quality labels of beef in three Spanish cities (Córdoba, Marbella, and Santa Pola) in a study performed with 300 individuals. Consumers were segmented according to their frequency of consumption. Willingness to pay for different meats was also calculated from the conjoint analysis results. Consumer liking of beef that had been finished with an alternative concentrate rich in agro-industrial by-products and aged for three different durations as compared to conventionally finished beef was also evaluated using the same consumers. The most important attribute for Spanish consumers was the price (28%), followed by origin (25%), animal welfare certification (19%), protected geographical indication (14%), and organic agriculture certification (14%). Most consumers preferred beef from Spain at the lowest possible price and with the highest number of quality labels. Consumers were willing to pay a premium of 1.49, 3.61, and 5.53 EUR over 14 EUR/kg for organic certification, protected geographical indication, and animal welfare certification, respectively. Sensory analysis revealed that, for regular consumers, beef finished with an alternative concentrate rich in agro-industrial by-products offered several hedonic advantages (color, flavor, and tenderness) when compared to beef finished using a conventional diet, while occasional consumers did not find any difference between the two kinds of meat

    Hybrid power system for distributed energy deploying biogas from municipal solid waste and photovoltaic solar energy in Mendoza, Argentina

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    The emission of greenhouse gases (GHG) generated from landfill biogas causes critical environmental and social issues. However, efficiently capturing and using biogas can reduce its environmental impact. In the metropolitan area of Mendoza, around 1,300 tons of municipal solid waste (MSW) are generated daily, and 65% of it goes to the El Borbollón landfill. The aim of this study was to present the results of implementing the first hybrid system for electricity generation from biogas and solar energy in a landfill. This alternative solution allows responsible management of MSW and diversifies the regional energy matrix. The production of biogas, its collection, conduction, treatment, conditioning for combustion, and electrical engineering aspects are analyzed within the technological complex operating under a grid-connected generation system. The results of the study show that with an average annual generation of 6,387 MWh/year and a reduction of GHG emissions between 44.1% and 70.5%, the use of MSW biogas in small cities can also be carried out as a climate change mitigation strategy in the framework of distributed generation
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