Recursos de colección

E-Prints Complutense (107.946 recursos)

En este archivo los docentes e investigadores de la UCM depositan sus documentos en acceso abierto (open access)

Estado = Publicado

Mostrando recursos 1 - 20 de 3.601

  1. Cross-sectional properties of the lower limb long bones in the Middle Pleistocene Sima de los Huesos sample (Sierra de Atapuerca, Spain)

    Rodríguez García, Laura; Carretero, José Miguel; García González, Rebeca; Arsuaga, Juan Luis
    The recovery to date of three complete and five partial femora, seven complete tibiae, and four complete fibulae from the Atapuerca Sima de los Huesos site provides an opportunity to analyze the biomechanical cross-sectional properties in this Middle Pleistocene population and to compare them with those of other fossil hominins and recent modern humans. We have performed direct comparisons of the cross-sectional geometric parameters and reduced major axis (RMA) regression lines among different samples. We have determined that Atapuerca Sima de los Huesos (SH) fossils have significantly thicker cortices than those of recent modern humans for the three leg bones at...

  2. The role of surface to bulk ratio on the development of magnetic anisotropy in high Ga content Fe100-xGax thin films

    Muñoz Noval, Álvaro; Fin, S.; Salas Colera, E.; Bisero, D.; Ranchal Sánchez, Rocío
    In this work we show the development of bulk in-plane magnetic anisotropy in high Ga-content (Ga = 28 at. %) Fe_(100-x)Ga_x thin films as the layer thickness increases. This result is in clear contrast with the generally reported decrease of this anisotropy with the film thickness. We propose the interrelation between the enhancement of the Ga-pair correlations and a collinear distortion of the bcc structure within the sample plane as the origin of the magnetic anisotropy. Our results have been obtained by employing a combination of long and local range structural probe techniques with bulk and surface magnetic characterization techniques....

  3. Probiotics in digestive, emotional, and pain-related disorders

    Roman, Pablo; Abalo, Raquel; Marco López, Eva María; Cardona, Diana
    In recent years, interest in the relationship between gut microbiota and disease states has grown considerably. Indeed, several strategies have been employed to modify the microbiome through the administration of different diets, by the administration of antibiotics or probiotics, or even by transplantation of feces. In the present manuscript, we focus specifically on the potential application of probiotics, which seem to be a safe strategy, in the management of digestive, pain, and emotional disorders. We present evidence from animal models and human studies, notwithstanding that translation to clinic still deserves further investigation. The microbiome influences gut functions as well as...

  4. Star formation in the nucleus of the galaxy NGC-5253

    González-Riestra, R.; Rego Fernández, Manuel Eduardo; Zamorano Calvo, Jaime
    Summary. Optical and ultraviolet spectroscopic observations of the nucleus of the galaxy NGC5253 are analyzed. This galaxy presents the typical features of an elliptical system at large distances from its center. However, its nucleus is dominated by an emission complex composed by severa) giant H rr regions. The analysis of the optical spectra shows that the metallic abundances in the nucleus of the galaxy are below the solar values. The presence of O stars can be deduced from the numerous absorption Iines present in the UV spectrum. The UV emission lines indicate a high effective temperature for the ionizing star...

  5. Marxismo y cuestión nacional, entrevista por Miguel Riera Montesinos

    Armesilla Conde, Santiago Javier; Riera Montesinos, Miguel
    Autor de un libro que ha desatado una intensa polémica en las redes (El marxismo y la cuestión nacional española), con lluvia de insultos incluida, Santiago Armesilla postula aquí un proyecto de España muy alejado del oficialmente dominante en el marxismo español. La polémica está servida.

  6. Integración política y desarrollo económico en la plataforma iberoamericana

    Armesilla Conde, Santiago Javier; Pérez Gañán, María del Rocío
    Desde la década de 1950, en el contexto de la Guerra Fría, Iberoamérica es clasificada como “Tercer Mundo” por los otros dos bloques en pugna, el bloque capitalista liderado por Estados Unidos y el bloque comunista liderado por la Unión Soviética. A partir de entonces, desde diversos paradigmas se ha intentado revertir esta clasificación internacional aplicando políticas de desarrollo concretas en cada país desde ideologías contrapuestas. Paralelamente, el continente ha tratado de conformar procesos de integración entre sus naciones con dispar éxito. Este trabajo plantea la necesidad de conocer y analizar los elementos que han conformado las ideas (y políticas)...

  7. Geometrically defined spin structures in ultrathin Fe₃O₄ with bulk like magnetic properties

    Ruiz Gómez, Sandra; Pérez García, Lucas; Mascaraque Susunaga, Arantzazu; Quesada, Adrian; Prieto, Pilar; Palacio, Irene; Martín García, Laura; Foerster, Michael; Aballe, Lucía; Figuera, Juan de la
    We have grown high quality magnetite microcrystals free from antiphase boundaries on Ru(0001) by reactive molecular beam epitaxy, conserving bulk magnetic properties below 20 nm thickness. Magnetization vector maps are obtained by X-ray spectromicroscopy and compared with micromagnetic simulations. The observed domain configurations are dictated purely by shape anisotropy, overcoming the possible influences of (magneto) crystalline anisotropy and defects, thus demonstrating the possibility of designing spin structures in ultrathin, magnetically soft magnetite at will.

  8. Evolución y tendencias del rentismo petrolero en el Ecuador 2001-2010

    Bäckström, Caroline
    Un estado rentista se caracteriza por una estructura económica poco diversificada y polarizada hacia el petróleo, fiscalidad petrolera alta y gestión de la renta regida bajo criterios políticos, además de una economía vulnerable ante las fluctuaciones del precio de petróleo. El presente trabajo concluye que estos rasgos se intensificaron en el Ecuador como consecuencia del cambio político del 2007. En particular se fortalecieron rasgos del sector público y objetivos de la gestión de la renta además de que aumentó la vulnerabilidad de la demanda a la evolución del precio de petróleo. Así, a pesar de los esfuerzos del gobierno por...

  9. Resource-theoretic approach to vectorial coherence

    Bosyk, G. M.; Bellomo, G.; Luis Aina, Alfredo
    We propose a formal resource-theoretic approach to assess the coherence between partially polarized electromagnetic fields. From this framework, we identify two resource theories for the vectorial coherence: polarization-sensitive coherence and polarization-insensitive coherence. For each theory, we find the set of incoherent states and a class of operations that preserve this set (i.e., the incoherent operations). Both resource theories are endowed with a certain preorder relation that provides a hierarchy among the coherence-polarization states; thus, a necessary condition to consider in deciding whether a quantity is proper to measure the vectorial coherence is that it respects such a hierarchy. Finally, we...

  10. Thermodynamics and criticality of supersymmetric spin chains with long-range interactions

    Finkel Morgenstern, Federico; González López, Artemio; León Yebra, Carlos; Rodríguez González, Miguel Ángel
    We study the thermodynamics and critical behavior of su(m|n) supersymmetric spin chains of Haldane-Shastry type with a chemical potential term. We obtain a closed-form expression for the partition function and deduce a description of the spectrum in terms of the supersymmetric version of Haldane's motifs, which we apply to obtain an analytic expression for the free energy per site in the thermodynamic limit. By studying the low-temperature behavior of the free energy, we characterize the critical behavior of the chains with 1 <= m, n <= 2, determining the critical regions and the corresponding central charge. We also show that...

  11. Gravitational lensing by eigenvalue distributions of random matrix models

    Martínez Alonso, Luis; Medina, Elena
    We propose to use eigenvalue densities of unitary random matrix ensembles as mass distributions in gravitational lensing. The corresponding lens equations reduce to algebraic equations in the complex plane which can be treated analytically. We prove that these models can be applied to describe lensing by systems of edge-on galaxies. We illustrate our analysis with the Gaussian and the quartic unitary matrix ensembles.

  12. Superfluid–Mott insulator transition and Bose–Einstein Condensation of phonons in ion traps

    Porras Torres, Diego; Cirac, J. Ignacio
    We show that transverse phonons in a set of trapped ions under the action of lasers are described by a Bose-Hubbard model whose parameters can be externally adjusted. The hopping of the phonons between different phonons is provided by the Coulomb interaction. On the other hand, the nonlinear terms in the interaction of the ions with a standing-wave provide us with the phonon-phonon interaction. We investigate the possibility of observing several quantum many-body phenomena, including (quasi) Bose-Einstein Condensation as well as a superfluid-Mott insulator quantum phase transition.

  13. Effective spin quantum phases in systems of trapped ions

    Deng, X.-L.; Porras Torres, Diego; Cirac, J. Ignacio
    A system of trapped ions under the action of off-resonant standing waves can be used to simulate a variety of quantum spin models. In this work, we describe theoretically quantum phases that can be observed in the simplest realization of this idea: quantum Ising and XY models. Our numerical calculations with the density matrix renormalization group method show that experiments with ion traps should allow one to access general properties of quantum critical systems. On the other hand, ion trap quantum spin models show a few unusual features due to the peculiarities of induced effective spin-spin interactions which lead to...

  14. Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens

    Pérez González, Pablo Guillermo; otros, ...
    Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to similar to 50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than x 2,000. A separate image, detected briefly 0.26 '' from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of greater than or similar to 3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars' light curves can yield evidence about the...

  15. Renormalization algorithm for the calculation of spectra of interacting quantum systems

    Porras Torres, Diego; Verstraete, Frank; Cirac, J. Ignacio
    We present an algorithm for the calculation of eigenstates with definite linear momentum in quantum lattices. Our method is related to the density matrix renormalization group, and makes use of the distribution of multipartite entanglement to build variational wave functions with translational symmetry. The algorithm is applied to the study of bilinear-biquadratic S=1 chains, in particular to the region of phase space between the dimerized and ferromagnetic phases.

  16. Quantum manipulation of trapped ions in two dimensional Coulomb crystals

    Porras Torres, Diego; Cirac, J. Ignacio
    We show that a large number of ions forming a 2D Coulomb crystal provides an almost ideal system for scalable quantum computation and quantum simulation. In particular, the coupling of the internal states to the motion of the ions transverse to the crystal plane allows one to implement two-qubit quantum gates. We analyze in detail the decoherence induced by anharmonic couplings, and show that very high gate fidelities can be achieved with current experimental setups.

  17. The CARMENES search for exoplanets around M dwarfs First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems

    Montes Gutiérrez, David; Cortés Contreras, Miriam; otros, ...
    Context. The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary companion (GJ 15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary systems (GJ 581 and GJ 876). Aims. We aim to report new precise optical radial velocity measurements for these planet hosts and test the overall capabilities of CARMENES. Methods. We combined our CARMENES precise Doppler measurements with those available from...

  18. Scattering of fermions in the Yukawa theory coupled to unimodular gravity

    González Martín, S.; Pérez Martín, Carmelo
    We compute the lowest order gravitational UV divergent radiative corrections to the S matrix element of the fermion + fermion → fermion + fermion scattering process in the massive Yukawa theory, coupled either to Unimodular Gravity or to General Relativity. We show that both Unimodular Gravity and General Relativity give rise to the same UV divergent contribution in Dimensional Regularization. This is a nontrivial result, since in the classical action of Unimodular Gravity coupled to the Yukawa theory, the graviton field does not couple neither to the mass operator nor to the Yukawa operator. This is unlike the General Relativity...

  19. Production of vector resonances at the LHC via WZ-scattering: a unitarized EChL analysis

    Delgado López, Rafael; Dobado González, Antonio; Espriu, D.; García García, C.; Herrero, M.J.; Marcano, X.; Sanz Cillero, Juan José
    In the present work we study the production of vector resonances at the LHC by means of the vector boson scattering W Z → W Z and explore the sensitivities to these resonances for the expected future LHC luminosities. We are assuming that these vector resonances are generated dynamically from the self interactions of the longitudinal gauge bosons, W_(L) and Z_(L), and work under the framework of the electroweak chiral Lagrangian to describe in a model independent way the supposedly strong dynamics of these modes. The properties of the vector resonances, mass, width and couplings to the W and Z...

  20. Brout-Englert-Higgs mechanism for accelerating observers

    Dobado González, Antonio
    In this work we consider the spontaneous symmetry breaking of the electroweak SU(2)_(L) × U(1)_(Y) gauge group into U(1)_(em) taking place in the Standard Model of particle physics as seen from the point of view of an accelerating observer. According to the Unruh effect, that observer detects the Minkowski vacuum as a thermal bath at a temperature proportional to the proper acceleration a. Then we show that (in a certain large N limit) when the acceleration is bigger than the critical value a_(c) = 4πv (where v is the Higgs vacuum expectation value), the electroweak SU(2)L × U(1)_(Y) gauge symmetry...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.