150 research outputs found

    Reconstruction of the second layer of Ag on Pt(111)

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    The reconstruction of an Ag monolayer on Ag/Pt(111) is analyzed theoretically, employing a vertically extended Frenkel-Kontorova model whose parameters are derived from density functional theory. Energy minimization is carried out using simulated quantum annealing techniques. Our results are compatible with the STM experiments, where a striped pattern is initially found which transforms into a triangular reconstruction upon annealing. In our model we recognize the first structure as a metastable state, while the second one is the true energy minimum

    Pion gas viscosity at low temperature and density

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    By using Chiral Perturbation Theory and the Uehling-Uhlenbeck equation we compute the viscosity of a pion gas, in the low temperature and low density regime, in terms of the temperature, and the pion fugacity. The viscosity turns out to be proportional to the squared root of the temperature over the pion mass. Next to leading corrections are proportional to the temperature over the pion mass to the 3/2.Comment: 15 pages, 4 figures. RevTeX

    Jump capacity in cerebral palsy soccer players

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    Los objetivos del presente estudio fueron determinar en jugadores de fútbol con parálisis cerebral la altura de vuelo durante la realización del salto sin contramovimiento y con contramovimiento, y observar la relación de las variables antropométricas y de la clase funcional con la altura de vuelo y con el índice elástico. Trece jugadores de fútbol 7 diagnosticados con parálisis cerebral participaron en el estudio. La altura de vuelo durante el salto sin contramovimiento (20.45±4.45 cm) y con contramovimiento (24.33±5.37 cm) fue inferior a la obtenida en otros estudios con jugadores de fútbol sin parálisis cerebral. La altura de los jugadores e índice de masa corporal mostraron una correlación significativa con la altura del salto con contramovimiento (r=0,67 y r=-0,71, respectivamente).The aims of the present study were to determine in elite soccer players with cerebral palsy the jump height during a squat jump and during a countermovement jump, and to observe the relationship of the anthropometric parameters and the functional class with the jump height and the elastic index. Thirteen “soccer 7” players diagnosed with cerebral palsy took part in the study. The jump height for a squat jump (20.45±4.45 cm) and a countermovement jump (24.33±5.37 cm) was lower than the obtained in other studies in soccer players without cerebral palsy. The height of the players and their body mass index showed a significant correlation with the jump height during a countermovement jump (r=0.67 and r=- 0.71)

    Physical consequences of P\neqNP and the DMRG-annealing conjecture

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    Computational complexity theory contains a corpus of theorems and conjectures regarding the time a Turing machine will need to solve certain types of problems as a function of the input size. Nature {\em need not} be a Turing machine and, thus, these theorems do not apply directly to it. But {\em classical simulations} of physical processes are programs running on Turing machines and, as such, are subject to them. In this work, computational complexity theory is applied to classical simulations of systems performing an adiabatic quantum computation (AQC), based on an annealed extension of the density matrix renormalization group (DMRG). We conjecture that the computational time required for those classical simulations is controlled solely by the {\em maximal entanglement} found during the process. Thus, lower bounds on the growth of entanglement with the system size can be provided. In some cases, quantum phase transitions can be predicted to take place in certain inhomogeneous systems. Concretely, physical conclusions are drawn from the assumption that the complexity classes {\bf P} and {\bf NP} differ. As a by-product, an alternative measure of entanglement is proposed which, via Chebyshev's inequality, allows to establish strict bounds on the required computational time.Comment: Accepted for publication in JSTA

    The tour de France:An updated physiologic review

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    From its initial inception in 1903 as a race premised on a publicity stunt to sell newspapers, the Tour de France had grown and evolved over time to become one of the most difficult and heralded sporting events in the world. Though sporting science and the Tour paralleled each other, it was not until the midlate 1980s, andespecially the midlate 1990s (with the use of heart-rate monitors) that the 2 began to unify and grow together. The purpose of this brief review is to summarize what is currently known of the physiological demands of the Tour de France, as well as of the main physiological profile of Tour de France competitors

    Chapter 10 - Industry

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    This chapter provides an update to developments on mitigation in the industry sector since the IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report (AR4) (IPCC, 2007), but has much wider coverage. Industrial activities create all the physical products (e.g., cars, agricultural equipment, fertilizers, textiles, etc.) whose use delivers the final services that satisfy current human needs. Compared to the industry chapter in AR4, this chapter analyzes industrial activities over the whole supply chain, from extraction of primary materials (e.g., ores) or recycling (of waste materials), through product manufacturing, to the demand for the products and their services. It includes a discussion of trends in activity and emissions, options for mitigation (technology, practices, and behavioural aspects), estimates of the mitigation potentials of some of these options and related costs, co-benefits, risks and barriers to their deployment, as well as industry-specific policy instruments. Findings of integrated models (long-term mitigation pathways) are also presented and discussed from the sector perspective. In addition, at the end of the chapter, the hierarchy in waste management and mitigation opportunities are synthesized, covering key waste-related issues that appear across all chapters in the Working Group III contribution to the IPCC Fifth Assessment Report (AR5)

    Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

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    We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. We have compared the kinetic roughening properties of NiW films with those of Ni films deposited under the same conditions, as assessed by Atomic Force Microscopy. The surface morphologies of both systems are super-rough at short times, but differ at long times: while a cauliflower-like structure dominates for Ni, the surfaces of NiW films display a nodular morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-Parisi- Zhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case: mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW). Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditions in which surface kinetics is hindered due to a complex reaction mechanism. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.Facultad de Ciencias Exacta

    Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

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    We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. We have compared the kinetic roughening properties of NiW films with those of Ni films deposited under the same conditions, as assessed by Atomic Force Microscopy. The surface morphologies of both systems are super-rough at short times, but differ at long times: while a cauliflower-like structure dominates for Ni, the surfaces of NiW films display a nodular morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-ParisiZhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case: mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW). Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditions in which surface kinetics is hindered due to a complex reaction mechanism. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.We acknowledge financial support from ANPCyT (PICT 2012-1808), CONICET (PIP 0671) and Universidad Nacional de La Plata (11X760) as well as from MINECO/FEDER (Spain/UE) Grants MAT2014-54231-C4-1-P, FIS2015-66020-C2-1-P and MAT2014-52405-C2-2-R, as well as by Comunidad Autónoma de Madrid (Spain) Grant NANOAVANSENS S2013/MIT-3029. M.E.V. is member of the research career of CICPB

    P67 195. Cirugía del tromboembolismo pulmonar masivo en el enfermo crítico

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    La extracción de los trombos pulmonares en el tromboembolismo pulmonar masivo antes de 1953 (operación de Trendelenburg) cosechó fracaso tras fracaso. Desde el advenimiento de la circulación extracorpórea (CEC) el porcentaje de éxito de esta operación mejoró notablemente, no habiendo dejado de aumentar hasta la actualidad, existiendo series que reflejan porcentajes de hasta el 94% de supervivencia inmediata, con 86 y 83% de supervivencia actuarial a 1 y 3años.Presentamos un caso de paciente varón de 35años sin enfermedad previa ni antecedentes familiares de enfermedad tromboembólica. Consulta por insuficiencia respiratoria, siendo diagnosticado por tomografía computarizada de tromboembolismo en AP izquierda, la cual ocluye. El ECO-Doppler de MMII descarta trombosis venosa profunda (TVP). Una nueva tomografía computarizada informa de persistencia de la obstrucción de AP izquierda y sus ramas, que parece haber aumentado. En ecocardiografía transtorácica (ETT) dilatación de cavidades derechas con función de ventrículo derecho (VD) normal y presión sistólica de la arteria pulmonar (PSAP) de 70 mmHg. Los estudios para investigar trombofilia fueron negativos.Tras unos días empeora su situación, produciéndose dos paradas cardiorrespiratorias, de las que es reanimado y tratado inmediatamente con TNK. La tomografía computarizada muestra la existencia de nuevo episodio de tromboembolismo pulmonar que afecta a la AP derecha gravemente.Es intervenido quirúrgicamente bajo CEC sin parada circulatoria, extrayéndose molde trombótico de tronco y ambas ramas de la AP. La evolución postoperatoria fue favorable. En tomografía computarizada de control se observan limpios el tronco y las ramas de la AP, con cierto compromiso en ramas subsegmentarias de la AP izquierda.Se muestran imágenes de la intervención y tomografía computarizada pre y posquirúrgicas
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