Ratchet behavior in nonlinear Klein-Gordon systems with point-like inhomogeneities

We investigate the ratchet dynamics of nonlinear Klein-Gordon kinks in a periodic, asymmetric lattice of point-like inhomogeneities. We explain the underlying rectification mechanism within a collective coordinate framework, which shows that such system behaves as a rocking ratchet for point particles. Careful attention is given to the kink width dynamics and its role in the transport. We also analyze the robustness of our kink rocking ratchet in the presence of noise. We show that the noise activates unidirectional motion in a parameter range where such motion is not observed in the noiseless case. This is subsequently corroborated by the collective variable theory. An explanation for this new phenomenom is given

Gender differences in motivation and perception of utility of the scholar spot

El principal objetivo del estudio es analizar las diferencias entre el nivel de autodeterminación y la satisfacción de las necesidades psicológicas básicas en función del género y su incidencia sobre la percepción de utilidad del deporte. Participaron en el estudio 1897 jóvenes jugadores de baloncesto, balonmano, fútbol y voleibol (1378 chicos y 519 chicas). Diferentes instrumentos fueron utilizados para medir las distintas variables abordadas en el estudio. Los resultados mostraron que los chicos presentan puntuaciones más altas en todos los tipos de motivación y que su sentimiento de competencia es más elevado que el de las chicas. Por otro lado, la motivación autodeterminada y la satisfacción de las necesidades conducen a percibir mayor utilidad del deporte en ambos génerosThe aim of the study was to analyze the differences between self-determination level and satisfaction of the three psychological needs with respect to gender and their influence on the perception of utility of the sport. The sample comprised 1897 basketball, handball, football and volleyball young players (1378 boys and 519 girls). Different measures were used to examine the differences between the variables contained in the study. Results showed that boys were more intrinsically and extrinsically motivated and showed less a motivation than girls, as well as their scored higher in competence than girls. However, both for boys and girls, self-determined motivation and psychological needs satisfaction led to a greater perception of utility of the spor

Analysis of the group process and the performance in semiprofessional soccer

El principal objetivo del estudio es aplicar un modelo teórico analizando dos de los antecedentes de la eficacia colectiva, el clima motivacional y la cohesión grupal, y su principal consecuencia como es el rendimiento. Los participantes fueron 203 futbolistas que participaban en el grupo XIV de la Liga Nacional de Tercera División, que rellenaron diversos instrumentos para valorar el clima motivacional, la cohesión y la eficacia colectiva. Los resultados obtenidos señalan que el modelo teórico que se aplica confirma que el clima que implica a la tarea predice la cohesión grupal. Además, la cohesión tarea se manifiesta como el principal predictor de la eficacia colectiva, y ésta a su vez del rendimiento. La principal conclusión es que para optimizar la percepción de eficacia colectiva y con ello, la mejora del rendimiento, parece fundamental que los entrenadores planteen estrategias para fomentar los aspectos tarea del clima motivacional y la cohesión grupal en los jugadores.The main aim of the study was to test a theoretical model examining two of the antecedents of the collective efficacy, motivational climate and group cohesion, as well as performance as their principal consequence. Participants were 203 footballers who played in the XIV group of National League in Third Division and filled several instruments to assess motivational climate, cohesion and collective efficacy. The theoretical model showed that mastery climate predicted group cohesion. Furthermore, task cohesion emerged as the strongest predictor of collective efficacy, and this variable predicted performance. The main conclusion is that to optimize perception of collective efficacy and so, increase performance, it seems important that coaches promote strategies to enhance task related motivational climate and group cohesion in players

Validation positive behaviors questionnaire in educative dance

El objetivo de la presente investigación era adaptar y validar al contexto de la danza educativa, el Cuestionario de Comportamientos Positivos en Educación Física. La muestra estuvo formada por 921 alumnos, de sexo femenino (n = 421) y masculino (n = 500), con edades comprendidas entre los 11 y los 17 años, pertenecientes a cuatro escuelas en México. Esta investigación estaba organizada por ConArte (Consorcio Internacional de Arte y Escuela). Los resultados obtenidos mostraron que el instrumento presentaba una adecuada validez factorial y consistencia interna. Asimismo, el instrumento se mostró invariante en cuanto al género y la edad de los participantes. De esta manera, este trabajo aporta evidencias científicas de que el cuestionario de comportamientos positivos en la danza educativa se muestra válido y fiable para analizar dichos comportamientos durante este tipo de clasesThe aim of the current research was to validate into the educative dance in Mexican secondary school, the questionnaire of positive behaviors in physical education. The sample was formed by 921 students, both female (n = 421) and male (n = 500) participants, ranging in age from 11 to 17 years old, belonged to four schools from Mexico. This research was organized by ConArte (International Consortium of Art and School). The results showed that the instrument had an adequate factorial validity and internal consistency. Furthermore, the instrument was invariant regarding individuals´ gender and age. Thus, this work gives empiric evidences that the questionnaire of positive behaviors in educative dance is valid and reliable to assess these behavior

Optimization of soliton ratchets in inhomogeneous sine-Gordon systems

Unidirectional motion of solitons can take place, although the applied force has zero average in time, when the spatial symmetry is broken by introducing a potential $V(x)$, which consists of periodically repeated cells with each cell containing an asymmetric array of strongly localized inhomogeneities at positions $x_{i}$. A collective coordinate approach shows that the positions, heights and widths of the inhomogeneities (in that order) are the crucial parameters so as to obtain an optimal effective potential $U_{opt}$ that yields a maximal average soliton velocity. $U_{opt}$ essentially exhibits two features: double peaks consisting of a positive and a negative peak, and long flat regions between the double peaks. Such a potential can be obtained by choosing inhomogeneities with opposite signs (e.g., microresistors and microshorts in the case of long Josephson junctions) that are positioned close to each other, while the distance between each peak pair is rather large. These results of the collective variables theory are confirmed by full simulations for the inhomogeneous sine-Gordon system

Comparative study of green sub- and supercritical processes to obtain carnosic acid and carnosol-enriched rosemary extracts with in vitro anti-proliferative sctivity on colon cancer cells

In the present work, four green processes have been compared to evaluate their potential to obtain rosemary extracts with in vitro anti-proliferative activity against two colon cancer cell lines (HT-29 and HCT116). The processes, carried out under optimal conditions, were: (1) pressurized liquid extraction (PLE, using an hydroalcoholic mixture as solvent) at lab-scale; (2) Single-step supercritical fluid extraction (SFE) at pilot scale; (3) Intensified two-step sequential SFE at pilot scale; (4) Integrated PLE plus supercritical antisolvent fractionation (SAF) at pilot scale. Although higher extraction yields were achieved by using PLE (38.46% dry weight), this extract provided the lowest anti-proliferative activity with no observed cytotoxic effects at the assayed concentrations. On the other hand, extracts obtained using the PLE + SAF process provided the most active rosemary extracts against both colon cancer cell lines, with LC50 ranging from 11.2 to 12.4 µg/mL and from 21.8 to 31.9 µg/mL for HCT116 and HT-29, respectively. In general, active rosemary extracts were characterized by containing carnosic acid (CA) and carnosol (CS) at concentrations above 263.7 and 33.9 mg/g extract, respectively. Some distinct compounds have been identified in the SAF extracts (rosmaridiphenol and safficinolide), suggesting their possible role as additional contributors to the observed strong anti-proliferative activity of CA and CS in SAF extracts.This work was supported by the projects AGL2014-53609-P (Ministerio de Economía y Competitividad, Spain) and S2013/ABI-2728 (Comunidad de Madrid).We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Leibnizian, Galilean and Newtonian structures of spacetime

The following three geometrical structures on a manifold are studied in detail: (1) Leibnizian: a non-vanishing 1-form $\Omega$ plus a Riemannian metric \h on its annhilator vector bundle. In particular, the possible dimensions of the automorphism group of a Leibnizian G-structure are characterized. (2) Galilean: Leibnizian structure endowed with an affine connection $\nabla$ (gauge field) which parallelizes $\Omega$ and \h. Fixed any vector field of observers Z ($\Omega (Z) = 1$), an explicit Koszul--type formula which reconstruct bijectively all the possible $\nabla$'s from the gravitational ${\cal G} = \nabla_Z Z$ and vorticity $\omega = rot Z/2$ fields (plus eventually the torsion) is provided. (3) Newtonian: Galilean structure with \h flat and a field of observers Z which is inertial (its flow preserves the Leibnizian structure and $\omega = 0$). Classical concepts in Newtonian theory are revisited and discussed.Comment: Minor errata corrected, to appear in J. Math. Phys.; 22 pages including a table, Late

Geminivirus replication protein decreases PCNA sumoylation at two acceptor sites

Geminiviruses are plant viruses with circular, single-stranded DNA (ssDNA) genomes that infect a broad range of plants causing substantial crop diseases worldwide. They replicate in nuclei of infected cells by using host DNA replication machinery and an essential protein encoded in their genome designated Rep (replication-associated protein). This multifunctional protein induces the accumulation of the host factors involved in replication and it is capable of interacting with a lot of plant proteins including PCNA (Proliferating Cell Nuclear Antigen), a processivity factor that coordinates a wide range of processes involved in maintenance, duplication and transmission of the genome, and the sumoylation enzyme that conjugates SUMO to target proteins (SUMO-conjugating enzyme- SCE). PCNA modification by SUMO, and also ubiquitin, has long been known to be of key importance for determining how DNA damage is processed by the replisome and for maintenance of overall genome integrity. In yeast, PCNA sumoylation has been associated to DNA repair involving homologous recombination (HR). Previously, we reported that Rep ectopic expression does not result in broad changes in the sumoylation pattern of plant cells, but it modifies the sumoylation state of selected host proteins. In this work, we show, using a reconstituted sumoylation system in Escherichia coli, that tomato PCNA is sumoylated at two residues, K254 and K164, and that co-expression of the Rep protein suppresses PCNA sumoylation at these lysines. Finally, we confirm that PCNA is sumoylated and that Rep also interferes with PCNA sumoylation in planta.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

LiLO: Lightweight and low-bias LiDAR Odometry method based on spherical range image filtering

In unstructured outdoor environments, robotics requires accurate and efficient odometry with low computational time. Existing low-bias LiDAR odometry methods are often computationally expensive. To address this problem, we present a lightweight LiDAR odometry method that converts unorganized point cloud data into a spherical range image (SRI) and filters out surface, edge, and ground features in the image plane. This substantially reduces computation time and the required features for odometry estimation in LOAM-based algorithms. Our odometry estimation method does not rely on global maps or loop closure algorithms, which further reduces computational costs. Experimental results generate a translation and rotation error of 0.86\% and 0.0036{\deg}/m on the KITTI dataset with an average runtime of 78ms. In addition, we tested the method with our data, obtaining an average closed-loop error of 0.8m and a runtime of 27ms over eight loops covering 3.5Km.Comment: This paper is under review at the journal "Autonomous Robots" (Springer

Una propuesta que facilita el uso eficaz de los libros de texto a los futuros profesores de matemáticas

En este trabajo se presentan los primeros resultados de una experiencia piloto desarrollada en el marco del Máster de Formación de Profesores de Matemáticas de Secundaria, Bachillerato e Idiomas (MFP) de la Universidad Rey Juan Carlos de Madrid (URJC), en la que se trata de obtener información, a través de cuestionarios diseñados a tal efecto por el equipo de investigadores que presenta esta propuesta, sobre qué conocimientos matemáticos específicos necesita un profesor de matemáticas para usar de manera eficaz en el aula el libro de texto. Como punto de partida, y a través del trabajo colaborativo de los autores de la propuesta aquí presentada, se ha diseñado un conjunto de ítems para analizar minuciosamente los contenidos de una Unidad Didáctica de un libro de texto