On the role of the nonlocal Hartree-Fock exchange in ab initio quantum transport: Hydrogen in Platinum nanocontacts revisited

We propose a practical way to overcome the ubiquitous problem of the overestimation of the zero-bias and zero-temperature conductance, which is associated to the use of local approximations to the exchange-correlation functional in Density-Functional Theory when applied to quantum transport. This is done through partial substitution of the local exchange term in the functional by the nonlocal Hartree-Fock exchange. As a non-trivial example of this effect we revisit the smallest molecular bridge studied so far: a Hydrogen molecule placed in between Platinum nanocontacts. When applied to this system the value of the conductance diminishes as compared to the local-exchange-only value, which is in close agreement with results predicted from Time-Dependent Current-Density-Functional Theory. Our results issue a warning message on recent claims of perfect transparency of a Hydrogen molecule in Platinum nanocontacts

Phase Separation Driven by External Fluctuations

The influence of external fluctuations in phase separation processes is analysed. These fluctuations arise from random variations of an external control parameter. A linear stability analysis of the homogeneous state shows that phase separation dynamics can be induced by external noise. The spatial structure of the noise is found to have a relevant role in this phenomenon. Numerical simulations confirm these results. A comparison with order-disorder noise induced phase transitions is also made.Comment: 4 pages, 4 Postscript figures included in text. LaTeX (with Revtex macros

Enfermería : fármacos más utilizados en urgencias hospitalarias

El Servicio de Urgencias del C.H.G.U.V. cuenta con una plantilla de 84 Enfermeros/as. Una parte considerable de ellos es personal de nueva incorporación, de ahí que sea prioritaria la elaboración de protocolos de actuación. La administración de medicación intravenosa es sin duda una de las técnicas de mayor aplicación en los pacientes que acuden a Urgencias, que en nuestro Hospital oscila entre 550-600 atenciones diarias. Por ello nos planteamos, mediante la realización de reuniones de grupo, la elaboración del presente trabajo con el objetivo de elaborar un manual informativo sobre la medicación más habitual utilizada en nuestro Servicio de Urgencias; indicaciones, contraindicaciones, diluciones, cuidados y recomendaciones sobre la administración que nos ayude a visionar la practica en nuestro trabajo y la calidad del Servicio que prestamos a nuestros pacientes, y sirva de consulta sobre todo al personal de nueva incorporación.The First aid service of the C.H.G.U.V. Nurse is provided with a staff of 84, a considerable part of them is new staff, and therefore there is a priority of making of performance protocols. The administration of intravenous medication is undoubtedly one of the most used techniques in patients who come to the emergency room, which in our Hospital ranges between 550-600 daily attentions. For this reason, we considered that carrying out group meetings in order to elaborate the present essay. Our main objective is to prepare an informative guidebook about the most common used medicines in our first aid service: indications, contraindications, dilutions, care, and recommendations on the use. In this sense it will contribute to see the practice in our work and the service quality that we give to our patients. And what is more, it will serve as a reference particularly to the new [email protected]

Obtaining the lattice energy of the anthracene crystal by modern yet affordable first-principles methods

The non-covalent interactions in organic molecules are known to drive their self-assembly to form molecular crystals. We compare, in the case of anthracene and against experimental (electronic-only) sublimation energy, how modern quantum-chemical methods are able to calculate this cohesive energy taking into account all the interactions between occurring dimers in both first-and second-shells. These include both O(N 6)- and O(N 5)-scaling methods, Local Pair Natural Orbital-parameterized Coupled-Cluster Single and Double, and Spin-Component-Scaled-Møller-Plesset perturbation theory at second-order, respectively, as well as the most modern family of conceived density functionals: double-hybrid expressions in several variants (B2-PLYP, mPW2-PLYP, PWPB95) with customized dispersion corrections (–D3 and –NL). All-in-all, it is shown that these methods behave very accurately producing errors in the 1–2 kJ/mol range with respect to the experimental value taken into account the experimental uncertainty. These methods are thus confirmed as excellent tools for studying all kinds of interactions in chemical systems.Financial support by the “Ministerio de Economía y Competitividad” of Spain and the “European Regional Development Fund” through projects CTQ2011-27253, CTQ2012-31914, and Consolider-Ingenio CSD2007-00010 in Molecular Nanoscience, and by the Generalitat Valenciana (ISIC 2012/008 and PROMETEO/2012/053) is acknowledged. The work in Mons is supported by the Belgian National Fund for Scientific Research (FNRS). Y.O. is a FNRS Post-doctoral Research Fellow. J.C.S.G. is a FNRS Visiting Professor

External Fluctuations in a Pattern-Forming Instability

The effect of external fluctuations on the formation of spatial patterns is analysed by means of a stochastic Swift-Hohenberg model with multiplicative space-correlated noise. Numerical simulations in two dimensions show a shift of the bifurcation point controlled by the intensity of the multiplicative noise. This shift takes place in the ordering direction (i.e. produces patterns), but its magnitude decreases with that of the noise correlation length. Analytical arguments are presented to explain these facts.Comment: 11 pages, Revtex, 10 Postscript figures added with psfig style (included). To appear in Physical Review

Noise-Induced Phase Separation: Mean-Field Results

We present a study of a phase-separation process induced by the presence of spatially-correlated multiplicative noise. We develop a mean-field approach suitable for conserved-order-parameter systems and use it to obtain the phase diagram of the model. Mean-field results are compared with numerical simulations of the complete model in two dimensions. Additionally, a comparison between the noise-driven dynamics of conserved and nonconserved systems is made at the level of the mean-field approximation.Comment: 12 pages (including 6 figures) LaTeX file. Submitted to Phys. Rev.

Intrinsic noise-induced phase transitions: beyond the noise interpretation

We discuss intrinsic noise effects in stochastic multiplicative-noise partial differential equations, which are qualitatively independent of the noise interpretation (Ito vs. Stratonovich), in particular in the context of noise-induced ordering phase transitions. We study a model which, contrary to all cases known so far, exhibits such ordering transitions when the noise is interpreted not only according to Stratonovich, but also to Ito. The main feature of this model is the absence of a linear instability at the transition point. The dynamical properties of the resulting noise-induced growth processes are studied and compared in the two interpretations and with a reference Ginzburg-Landau type model. A detailed discussion of new numerical algorithms used in both interpretations is also presented.Comment: 9 pages, 8 figures, to be published in Phys. Rev.

Estudio biomecánico in vivo del grupo muscular flexor del codo en condiciones basales y su respuesta a la fatiga.

El objetivo del presente trabajo es establecer una aproximación al patrón de referencia habitual de la biomecánica del bíceps braquial y su respuesta a la fatiga. Sobre 37 voluntarios varones sanos se determinó una capacidad de contracción voluntaria máxima de flexión del codo de 266,8 ± 58,7N en el brazo dominante y de 258,2 ± 59,4N en el no dominante, que descendió a 211,5 ± 53N y 205,3 ± 56,5N respectivamente al someter a los voluntarios al test de fatiga (p<0,001 en ambos). El tiempo de fatiga se objetivó en 160,7 ± 72,8 s en el brazo dominante y en 156,7 ± 68,7 s en el no dominante. La supinación voluntaria máxima disminuyó de 208,7 ± 54N y 207 ± 54,8N hasta 194,1 ± 66,6N y 192,8 ± 66N respectivamente en el estudio postfatiga (p<0,001 en ambas). No se apreciaron diferencias significativas en el estudio de subgrupos por edades

Noise-Driven Mechanism for Pattern Formation

We extend the mechanism for noise-induced phase transitions proposed by Ibanes et al. [Phys. Rev. Lett. 87, 020601-1 (2001)] to pattern formation phenomena. In contrast with known mechanisms for pure noise-induced pattern formation, this mechanism is not driven by a short-time instability amplified by collective effects. The phenomenon is analyzed by means of a modulated mean field approximation and numerical simulations