3,746 research outputs found

    Datos brioflorísticos sobre el sector Marianico-Monchiquense (Península Ibérica)

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    Se presenta un catálogo brioflorístico del sector Mariánico-Monchiquense de la provincia corológica Luso-Extremadurense. Se citan un total de 176 táxones y se caracteriza el territorio desde el punto de vista geográfico, geológico y bioclimático.A check-list of the Mariánico-Monchiquense sector of the Luso-Extremadurense chorological province is presented. A total of 176 species have been identificated. The geographical, geological and bioclimatics characters, are also give

    Ultrafast single electron spin manipulation in 2D semiconductor quantum dots with optimally controlled time-dependent electric fields through spin-orbit coupling

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    We have studied theoretically the possibility of ultra-fast manipulation of a single electron spin in 2D semiconductor quantum dots, by means of high-frequency time-dependent electric fields. The electron spin degree of freedom is excited through spin-orbit coupling, and the procedure may be enhanced by the presence of a static magnetic field. We use quantum optimal control theory to tailor the temporal profile of the electric field in order to achieve the most effective manipulation. The scheme predicts significant control over spin operations in times of the order of picoseconds – an ultrafast time scale that permits to avoid the effects of decoherence if this scheme is to be used as a tool for quantum information processing

    Tribological and mechanical properties of graphene nanoplatelet/PEEK composites

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    Poly(ether ether ketone) (PEEK) is a relevant thermoplastic in industry and in the biomedical sector. In this work, the lubricant capability of graphene nanoplatelets (GNPs) is used for improving the PEEK wear properties. Nanocomposites were prepared by solvent-free melt-blending and injection molding at various compositions between 1 and 10 wt. % of GNPs. The Raman G band shows a progressive increment proportional to the bulk GNP percentage. From calorimetric data, the polymer matrix structure is interpreted in terms of a 3-phase model, in which the crystalline phase fluctuates from 39 to 34% upon GNP addition. Thermal conductivity varies in accordance with the polymer crystallinity. Tensile and flexural tests show a progressive increase in the modulus, as well as a decrease in the fracture strength and the work of fracture. Most important, the composite surface undergoes a substantial improvement in hardness (60%), together with a decrease in the coefficient of friction (-38%) and a great reduction in the wear factor (-83%). Abrasion and fatigue wear mechanisms are predominant at the lowest and highest GNP concentrations respectively. In conclusion, GNPs are used without any chemical functionalization as the filler in PEEK-based materials, improving the surface hardness and the tribological properties

    Characteristics and energy dependence of recurrent galactic cosmic-ray flux depressions and of a forbush decrease with LISA Pathfinder

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    The final publication is available at IOS Press through http://dx.doi.org/10.3847/1538-4357/aaa774Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by the solar activity, the solar polarity and structures of solar and interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder, meant for subsystems diagnostics, was devoted to the measurement of GCR and solar energetic particle integral fluxes above 70 MeV n-1 up to 6500 counts s-1. PD data were gathered with a sampling time of 15 s. Characteristics and energy dependence of GCR flux recurrent depressions and of a Forbush decrease dated 2016 August 2 are reported here. The capability of interplanetary missions, carrying PDs for instrument performance purposes, in monitoring the passage of interplanetary coronal mass ejections is also discussed.Peer ReviewedPreprin

    Scattering of a proton with the Li4 cluster: non-adiabatic molecular dynamics description based on time-dependent density-functional theory

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    We have employed non-adiabatic molecular dynamics based on time-dependent density-functional theory to characterize the scattering behaviour of a proton with the Li4_4 cluster. This technique assumes a classical approximation for the nuclei, effectively coupled to the quantum electronic system. This time-dependent theoretical framework accounts, by construction, for possible charge transfer and ionization processes, as well as electronic excitations, which may play a role in the non-adiabatic regime. We have varied the incidence angles in order to analyze the possible reaction patterns. The initial proton kinetic energy of 10 eV is sufficiently high to induce non-adiabatic effects. For all the incidence angles considered the proton is scattered away, except in one interesting case in which one of the Lithium atoms captures it, forming a LiH molecule. This theoretical formalism proves to be a powerful, effective and predictive tool for the analysis of non-adiabatic processes at the nanoscale.Comment: 18 pages, 4 figure

    Automated procedures for the comparative analysis of HLA class I-bound peptide repertoires

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    Temperature- and pressure-dependent structural study of {Fe(pmd) 2[Ag(CN)2 ]2}n spin-crossover compound by neutron Laue diffraction

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    The effect of pressure (up to 0.17 GPa) on the spin-crossover compound {Fe(pmd)2[Ag(CN)2]2}n [orthorhombic isomer (II), pmd = pyrimidine] has been investigated by temperature- and pressure-dependent neutron Laue diffraction and magnetometry. The cooperative high-spin ¿ low-spin transition, centred at ca 180 K at ambient pressure, is shifted to higher temperatures as pressure is applied, showing a moderate sensitivity of the compound to pressure, since the spin transition is displaced by ca 140 K GPa-1. The space-group symmetry (orthorhombic Pccn) remains unchanged over the pressure–temperature (P–T) range studied. The main structural consequence of the high-spin to low-spin transition is the contraction of the distorted octahedral [FeN6] chromophores, being more marked in the axial positions (occupied by the pmd units), than in the equatorial positions (occupied by four [Ag(CN)2]- bridging ligands)

    Mupai animado: propuestas educativas para adolescentes sobre técnicas de animación en la creación audiovisual

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    With this article is tried to share the experience about the introduction of the more usual animation techniques in the contents of the educational project Vacaciones de cine, in its editions of 2009. Techniques as fl ipbook, stop-motion or pixilation have been used by the participants of this activity in the realization of audiovisual pieces. Due to the good reception of this project, has been decided starting similar activities in other context, which are going to be briefl y described along this article. To fi nish, are going to be put forward the conclusions about the relationship between teenagers and the use of animation techniques like expressive resort.Con este artículo se pretende compartir la experiencia de la introducción de las técnicas de animación más habituales en la creación audiovisual, entre los contenidos del proyecto educativo Vacaciones de cine, en sus ediciones de 2009. Técnicas como el fl ipbook, el stop-motion o la pixilación han sido utilizadas por los participantes de la actividad, en la realización de piezas audiovisuales. Debido a la buena acogida de este proyecto, se ha decidido poner en marcha actividades similares en otros contextos; las cuales serán brevemente descritas a lo largo del presente artículo. Para finalizar, se expondrán unas conclusiones sobre la relación existente entre el público adolescente y el empleo de las técnicas de animación como recurso expresivo

    A software tool for monitoring legal minimum lenght of landings: Case study of a fishery in sourthern Spain

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    Herramienta de interés para el control y la gestión de pesqueríasThe regulation of minimum legal size(MLS) of catches is a tool widely applied in the management of fisheries resources, although the MLS does not always coincide with the length at first maturit(LFM). The optimization of this management tool requires a series of quality control in fish markets and transportation. A software application has been developed to make the control of the landings of several target species easier and faster. In order to test and make this tool operational,six species of commercial interest were selected: four species of fish hand two species of bivalves. It is proposed to estimate the proportion of illegal specimens in the studied lot from the proportion of illegal individuals found in the samples taken from this lot.The input data for the application are the minimum legal size(MLS) of the species and the total length(TL)of each specimen sampled. The out put data is a statistical summary of the percentage of specimens of size less than the legal minimum(TL<=MLS)within different confidence intervals(90%,95% and 99%). The software developed will serve as a fast,efficient and easy to manage tool that allows inspectors to determine the degree of compliance on MLS control and to make a decision supported by statistical proof on fishing goods
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