Thermal and electrohydrodynamic plumes: a compartive study

This paper deals with self similar thermal and electrohydrodynamic (EHD) plumes. The former arises from hot lines or points, whereas the latter arises when sharp metallic contours submerged in non conducting liquids support high electrostatic potential, resulting in charge injection. Although the motive force is buoyancy in one case and Coulomb force in the other, it is shown that the solution for EHD plumes is the same as for thermal plumes in the limit of large Prandtl numbers. We present the analysis of axisymmetric plumes for large values of Prandtl number, and this analysis is subsequently applied to EHD plumes. The validity of the approximations for EHD plumes is discussed in the light of experimental data.Ministerio de ciencia y tecnología PB93-118

The Success Story of Gold-Based Catalysts for Gas- and Liquid-Phase Reactions: A Brief Perspective and Beyond

Gold has long held the fascination of mankind. For millennia it has found use in art, cosmetic metallurgy and architecture; this element is seen as the ultimate statement of prosperity and beauty. This myriad of uses is made possible by the characteristic inertness of bulk gold; allowing it to appear long lasting and above the tarnishing experienced by other metals, in part providing its status as the most noble meta

Embodied Lifelong Learning for Task and Motion Planning

A robot deployed in a home over long stretches of time faces a true lifelong learning problem. As it seeks to provide assistance to its users, the robot should leverage any accumulated experience to improve its own knowledge to become a more proficient assistant. We formalize this setting with a novel lifelong learning problem formulation in the context of learning for task and motion planning (TAMP). Exploiting the modularity of TAMP systems, we develop a generative mixture model that produces candidate continuous parameters for a planner. Whereas most existing lifelong learning approaches determine a priori how data is shared across task models, our approach learns shared and non-shared models and determines which to use online during planning based on auxiliary tasks that serve as a proxy for each model's understanding of a state. Our method exhibits substantial improvements in planning success on simulated 2D domains and on several problems from the BEHAVIOR benchmark

Two-Level Systems and Boson Peak Remain Stable in 110-Million-Year-Old Amber Glass

The two most prominent and ubiquitous features of glasses at low temperatures, namely the presence of tunneling two-level systems and the so-called boson peak in the reduced vibrational density of states, are shown to persist essentially unchanged in highly stabilized glasses, contrary to what was usually envisaged. Specifically, we have measured the specific heat of 110 million-year-old amber samples from El Soplao (Spain), both at very low temperatures and around the glass transition Tg. In particular, the amount of two-level systems, assessed at the lowest temperatures, was surprisingly found to be exactly the same for the pristine hyperaged amber as for the, subsequently, partially and fully rejuvenated samples.Comment: 22 pages, 9 figures, 2 tables (including Supplementary Material

A study of temperature-related non-linearity at the metal-silicon interface

In this paper, we investigate the temperature dependencies of metal-semiconductor interfaces in an effort to better reproduce the current-voltage-temperature (IVT) characteristics of any Schottky diode, regardless of homogeneity. Four silicon Schottky diodes were fabricated for this work, each displaying different degrees of inhomogeneity; a relatively homogeneous NiV/Si diode, a Ti/Si and Cr/Si diode with double bumps at only the lowest temperatures, and a Nb/Si diode displaying extensive non-linearity. The 77–300 K IVT responses are modelled using a semi-automated implementation of Tung's electron transport model, and each of the diodes are well reproduced. However, in achieving this, it is revealed that each of the three key fitting parameters within the model display a significant temperature dependency. In analysing these dependencies, we reveal how a rise in thermal energy “activates” exponentially more interfacial patches, the activation rate being dependent on the carrier concentration at the patch saddle point (the patch's maximum barrier height), which in turn is linked to the relative homogeneity of each diode. Finally, in a review of Tung's model, problems in the divergence of the current paths at low temperature are explained to be inherent due to the simplification of an interface that will contain competing defects and inhomogeneities

Pattern of injuries in beach volleyball at the spanish national university championship

Este artículo pretende establecer y determinar las lesiones más frecuentes en jugadores de vóley playa universitarios a través de una muestra de 33 participantes en el Campeonato de España Universitario. Para estudiar las lesiones, se realizó una entrevista personal mediante un cuestionario validado. Los resultados mostraron que la región corporal con mayor incidencia lesiva fue el tobillo (33,3%), seguido de los dedos de la mano (18,5%), las rodillas (13,0%), los hombros (11,1%) y la espalda (5,6%). Además también se obtuvieron datos sobre el momento de la lesión (competición o entrenamiento), su origen (impacto o sobreuso) y característica de la lesión (nueva lesión o repetida). El tratamiento de los datos para el establecimiento de las diferencias significativas se realizó a través de la prueba estadística Chi-Cuadrado. Los resultados establecen un patrón de lesiones diferente al que se produce en vóley playa profesional, probablemente como consecuencia directa del nivel, horas de entrenamiento y exigencia del juegoThe aim of this paper is to study the most common injuries in university beach volleyball players. The sample consisted in 33 athletes participating in the University Spanish Championship. Injuries were assessed by means of personal interviews and a validated questionnaire. Results show that the body region with the highest incidence was the ankle (33%), followed by the fingers (18.5%), knees (13.0%), shoulders (11.1%) and back (5.6%). Also, information on the moment of injury (competition or training), origin (impact or overuse) and characteristic of the injury (new or recurrent injury). Statistical processing of data for establishing significant differences was performed using the Chi-square test. Results showed a harmful effect, which differs from that of professional volley players, probably as a result of the level, hours of training and requirements of the gam

Effect of the Ozonization Degree of Emu Oil over Healing: An Emerging Oxidation Treatment

This chapter deals with the ozonization process of the emu oil, the objective of this study was to quantitatively determine the peroxide value (PV) to measure the degree of ozonation, the peroxide value measures the number of peroxide groups in the ozonized oil. The ozone oxidizes the unsaturated chemical functions present in the oil giving a high cure rate for epidermal wounds. The healing process is not completely understood and there are different approaches, therefore, it was determined qualitatively if it has healing and inflammation properties, but the results of our studies have shown that the length and width of the wounds were healing quickly thanks to the peroxidation rate of the oils. In addition, both tests were correlated to obtain a greater appreciation of their functions, the mechanism involves a decrease in the inflammation of the wounds and stimulates the process of scar formation