A Pulse Shaping Algorithm of a Coherent Matter Wave. Controlling Reaction Dynamics

A pulse shaping algorithm for a matter wave with the purpose of controlling a binary reaction has been designed. The scheme is illustrated for an Eley-Rideal reaction where an impinging matter-wave atom recombines with an adsorbed atom on a metal surface. The wave function of the impinging atom is shaped such that the desorbing molecule leaves the surface in a specific vibrational state.Comment: 4 pages, 5 figure

EFFECTS OF SHORT-TERM SLED TOWING AND UNLOADED SPRINT TRAINING ON LEG POWER AND STIFFNESS

The relationship between stiffness and athletic performance is of great interest to the sport and research communities. Unfortunately, there are no longitudinal studies that have investigated the effects of strength or power training on mechanical stiffness in sprinters. The aim of the study was to examine the effect of resisted and unloaded sprint training programs on sprint time, leg power, and stiffness

Classical emulation of quantum-coherent thermal machines

The performance enhancements observed in various models of continuous quantum thermal machines have been linked to the buildup of coherences in a preferred basis. But, is this connection always an evidence of `quantum-thermodynamic supremacy'? By force of example, we show that this is not the case. In particular, we compare a power-driven three-level continuous quantum refrigerator with a four-level combined cycle, partly driven by power and partly by heat. We focus on the weak driving regime and find the four-level model to be superior since it can operate in parameter regimes in which the three-level model cannot, it may exhibit a larger cooling rate, and, simultaneously, a better coefficient of performance. Furthermore, we find that the improvement in the cooling rate matches the increase in the stationary quantum coherences exactly. Crucially, though, we also show that the thermodynamic variables for both models follow from a classical representation based on graph theory. This implies that we can build incoherent stochastic-thermodynamic models with the same steady-state operation or, equivalently, that both coherent refrigerators can be emulated classically. More generally, we prove this for any N-level weakly driven device with a `cyclic' pattern of transitions. Therefore, even if coherence is present in a specific quantum thermal machine, it is often not essential to replicate the underlying energy conversion process.Comment: 13 pages, 4 figures; references updated; appendix adde

EFFECTS OF UPHILL RUNNING ON SPRINTING TECHNIQUE IN FOOTBALL PLAYERS

The success in many actions in team sports is determined by the player’s ability to develop high speed and acceleration. There are many resisted methods for training the strength within the specific running technique, each one with different application according to the characteristics of the overload. Uphill sprinting is one of these methods. A criticism related to the use of resisted methods is that the athletes may use a modified running technique and so subsequently could alter their movement pattern if repeated in time (e.g. Alcaraz et al. (2008) showed that some methods modify the body lean). The purpose of this work was to clarify the effects of uphill sprinting on variables related to the running performance and technique in football players

Efecto de un trabajo de aprendizaje del ciclo estiramiento-acortamiento sobre la capacidad de salto en voleibol

El propósito de esta investigación es conocer el efecto sobre la capacidad de salto (tiempo de ejecución y altura alcanzada por el centro de gravedad) de un trabajo de aprendizaje de la utilización del ciclo estiramiento - acortamiento de la musculatura flexora - extensora del pie a través de ejercicios de técnica de carrera realizados de forma integrada dentro del entrenamiento. Se realizó un estudio intergrupo con 12 jugadores de voleibol de nivel nacional divididos aleatoriamente en dos grupos (experimental y control). Todos los jugadores realizaron el mismo entrenamiento durante el periodo de estudio (primer macrociclo competitivo). El grupo experimental desarrolló de forma adicional en la parte final del calentamiento el trabajo de aprendizaje tres días por semana durante 14 semanas. Antes y después del trabajo de aprendizaje se realizó una batería de control, en donde se registró la altura alcanzada y el tiempo de impulso, en fase excéntrica y concéntrica. El grupo experimental consiguió una mejora significativa (disminución) a nivel de tiempo de la contracción excéntrica y del tiempo total de impulso en la prueba de bloqueo con desplazamiento lateral sin cruce. Respecto a la altura alcanzada no se observa diferencia entre ambos grupos. El efecto de un trabajo de aprendizaje produce una ganancia temporal en la acción de bloqueo con desplazamiento lateral sin cruce en voleibol aplicando los mismos niveles de fuerza (altura alcanzada)