The purpose of the present study is to explore the synoptic-scale atmospheric circulation and water vapor transport that contribute to triggering landslides in the mid-Elqui basin (30°S, 70.5°W) ...since the early 20th century. A total of 12 storms during the modern period (1957–2017) were identified from various sources and analyzed using ERA5 Reanalysis data. An additional set of eight storms was included and characterized using 20th Century Reanalysis data. The results reveal that high-amplitude, deep troughs extending into the subtropics off the west coast of South America are ubiquitous in these storms. Maximum integrated water vapor transport from the northwest (NW) or west-northwest (WNW) was observed on the coast (25–30°S), with values sometimes exceeding 300 kg s-1 m-1, often reaching more than five standard deviations above the mean. Atmospheric rivers near the study region were found to be involved in all 12 modern landslide-producing storms. Moreover, most storms occur during the warm phase of the El Niño–Southern Oscillation (ENSO) and/or phases 7–8–1 of the Madden–Julian Oscillation (MJO). Backward-trajectory analyses indicate that in all but one of the modern storms, water vapor transport originated in the Central Tropical Pacific, where ocean warming characterizes the convective phases of ENSO and/or MJO.
•Landslides in northern Chile are tied to cyclonic perturbations and atmospheric rivers.•Long-range water vapor transport is crucial, reaching 5 std. Deviations above mean at 30°S.•Landslide storms linked to warm ENSO phase and MJO phases 7–8–1, driven by teleconnections.
An open fully connected system of qubits at nonzero temperature is driven within a finite time interval along various paths in the space of its control parameters. The driving leads across ...finite-size precursors of the first- and second-order quantum phase transition from factorized to entangled ground-state phases, aiming at the preparation of the complex ground state of the system at the final parameter point with maximal fidelity. During the drive, the system is coupled to a heat bath with a constant temperature, the dynamics being determined in a nonpertubative way by the method of Hierarchical Equations of Motion. It is shown that the presence of the heat bath in combination with specific patterns of avoided crossings affecting the ground and excited states in the parameter region around the quantum phase transition may considerably improve the fidelity of preparation of the target ground state.
El objetivo fue determinar las diferencias en la calidad del control postural entre gimnastas rítmicas con diferente experiencia en la realización de habilidades propias de la disciplina. Las ...habilidades evaluadas fueron Espagat lateral con ayuda (ELCA), el Círculo con ayuda (CCA) y Espagat atrás sin ayuda (EASA), consideradas las que generan mayor activación muscular y cambios en el centro de presión (CDP). El estudio involucró 19 gimnastas rítmicas, 9 del grupo novatas, (menos de 4 años de experiencia), y 10 del grupo expertas (más de 4 años de experiencia). La ejecución de las habilidades deportivas, se realizó sobre una plataforma de fuerza (modelo: BP5050. Bertec, USA), donde se evaluó el área y velocidad de desplazamiento del centro de presión. El área de desplazamiento del centro de presión, fue mayor para todas las habilidades en las gimnastas novatas, en comparación con las experimentadas, siendo estadísticamente significativa, en la habilidad ELCA. La habilidad que presentó mayor desplazamiento del centro de presión en gimnastas novatas fue ELCA, y para las expertas el EASA. Según los resultados, la experiencia influye en un mejor control postural, por lo tanto se debe comenzar desde edades temprana a enfocar trabajos destinados a mejorar esta variable, permitiendo mayor eficacia y eficiencia en este deporte, optimizar la elaboración de los entrenamientos y disminuir el riesgo de lesiones.
Palabras Claves: Gimnasia Rítmica, Equilibrio Postural, Experiencia, Centro de Presión, Deporte.
Abstract. The objective was to determine the differences in the quality of postural control between rhythmic gymnasts with different experience in performing skills specific to the discipline. The skills evaluated were Assisted Lateral Split (ELCA), Assisted Circle (CCA) and Unaided Back Split (EASA), considered those that generate the greatest muscle activation and changes in the center of pressure (CDP). The study involved 19 rhythmic gymnasts, 9 from the novice group (less than 4 years of experience), and 10 from the expert group (more than 4 years of experience). The execution of the sports skills was carried out on a force platform (model: BP5050. Bertec, USA), where the area and displacement speed of the center of pressure were evaluated. The area of displacement of the center of pressure was greater for all skill in novice gymnasts, compared to the experienced gymnasts, being statistically significant, in the ELCA skill. The skill that presented the greatest displacement of the center of pressure in novice gymnasts was ELCA, and for experts it was EASA. According to the results, experience influences better postural control, therefore we should start from an early age to focus on work aimed at improving this variable, allowing greater effectiveness and efficiency in this sport, optimizing the development of training and reducing the risk of injuries.
Keywords: Rhythmic Gymnastics, Postural Balance, Experience, Pressure Center, Sport.
Three analytic solutions to the Schr\"{o}dinger equation for the time-dependent Landau-Zener Hamiltonian are presented. They correspond to specific finite-time driving paths in a bounded parameter ...space of a two-level system. Two of these paths go through the avoided crossing of levels, either with a constant speed or with variable speed that decreases in the region of reduced energy gap, the third path bypasses the crossing such that the energy gap remains constant. The solutions yield exact time dependencies of the excitation probability for the system evolving from the ground state of the initial Hamiltonian. The Landau-Zener formula emerges as an approximation valid within a certain interval of driving times for the constant-speed driving through the avoided crossing. For long driving times, all solutions converge to the prediction of the adiabatic perturbation theory. The excitation probability vanishes at some discrete time instants.
Objective: To study the haemodynamic properties of the peripheral circulation and its relationship with cardiorespiratory control, during anaerobic muscle fatigue test, in young competitive athletes. ...Method: Nine adolescent of national and international competition level were recruited (age: 15.6 ± 1.9 years; male = 7) and cross-evaluated. Morphological measurements (body mass, percentage of total body fat and height), blood pressure (systolic, diastolic, mean and pulse blood pressure), respiratory measures (spirometry and pimometry), power, and fatigue were recorded through Wingate test. Results: Weight, height, and fat-free mass were positively correlated with the power parameters of the Wingate test (p < 0.05). The respiratory parameters of forced vital capacity, peak expiratory flow, maximum inspiratory pressure (MIP) and maximum sustained pressure (SMIP) were also significantly correlated with the power parameters. Additionally, the cardiorespiratory parameters of MIP and SMIP were positively correlated with pulse pressure at rest (p < 0.05). Conclusion: The increase in MIP and SMIP is associated with a lower arterial compliance, which indicates that a lower vascular elasticity influences a greater diaphragmatic strength and endurance of the young athlete.
Using the adiabatic perturbation theory of driven dynamics Phys. Rev. A 78, 052508 (2008) we design a hierarchy of quantum state preparation protocols that systematically increase the fidelity at ...very long driving times. We test these and other protocols, including those based on the geometric analysis of the parameter space, in a single-qubit system and in a fully connected multi-qubit system showing in its infinite-size limit several quantum phase transitions. The new protocols excel in the asymptotic driving regime, above a crossover time from the Landau-Zener regime which increases with a decreasing minimal energy gap along the driving path (with the size of the system). In the medium-time domain, the performance of all tested protocols is indecisive.
We propose a protocol for transitionless driving of a bound quantum system in its parameter space using repeated measurement-like interactions with an external spectator system. As a consequence of ...the quantum Zeno effect, the fidelity of the final state preparation is equal to unity in the limit of infinite-rate interactions. For finite-rate interactions, the maximal fidelity is achieved for the driving trajectory having a minimal geometric length and keeping a constant speed with respect to the Provost-Vallee metric in the parameter space. We numerically test the protocol in an interacting multiqubit system, demonstrating its dominance over the method of coherent driving.
