Search results for " física"
showing 10 items of 920 documents
Cobalt ferrite nanoparticles under high pressure
2015
We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe2O4) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B0 = 204 GPa) is consid…
Relationship between muscular extensibility, strength and stability and the transmission of impacts during fatigued running
2020
The aim was to analyse the relationship between isokinetic strength, dynamic stability, muscular extensibility and impacts transmission during fatigued running. Low- and high-frequency impacts related to body movements and the severity of impacts, respectively were assessed in 17 male recreational runners, before and after a treadmill running fatigue protocol, using a triaxial accelerometry system. High-frequency impacts in the tibia were negatively correlated to the knee angle at which the quadriceps peak torque was reached (p = 0.014), and also to the extensibility of the hamstrings and soleus (p = 0.001 and p = 0.023, respectively). The increases of high-frequency impacts in tibia caused…
Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator.
2013
We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power. Fil: Cuadrado Laborde, Christian Ariel. Universidad de Valencia; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de In…
High-repetition rate acoustic-induced Q-switched all-fiber laser
2005
We report a high repetition rate actively Q switched all fiber laser. The acousto optic interaction controls the cou pling between co propagating core and cladding modes and is used to modulate the optical losses of the cavity, which permits to perform active Q-switching. Using 1.4 m of 300 ppm Er-doped fiber and a maximum pump power of 120 mW, we have obtained up to 1 W peak power pulses, with a pulse repetition rate that can be continuously varied from 1 Hz to 120 kHz and a pulse width that changes from 70 ns to 2.2 μs.
Critical incidents which limit performance of Chilean University rowers who won a medal in the Pan American Games of Lima 2019
2020
Main objective of this study was to provide a basis for the comprehension of the main critical incidents (i.e. obstacles) that Chilean rowers who were medallists in the Pan American Games of Lima 2019 have to face within the academic, socioeconomic and sports processes. 19 athletes were selected through a non-probabilistic sampling. A content validated questionnaire and an in-deep interview were used. Higher levels of consistency were observed. Through the inferential analysis (ANOVA) it was possible to conclude that athletes are concerned with some academic and social crisis within their sporting career. This fact does not allow them to concentration and integral tranquillity to be focused…
The effects of modifying contact, duration, and teaching strategies in awareness interventions on attitudes towards inclusion in physical education
2020
This quasi-experimental study analyses the effects of an awareness intervention programme with five different branches designed to improve the attitudes of physical education (PE) students towards the inclusion of classmates with disabilities. The contact (yes/no) and its frequency (×1 vs. ×3) with para-athletes, the duration of the programme (1 vs. 6/7 sessions), and the provision of teaching strategies and materials (yes/no) were manipulated. The study involved 603 students aged 14‒19 from five public educational centres in southern Spain. Attitudes were assessed pre- and post-intervention with the Spanish version of the Children's Attitude towards Integrated Physical Education (general a…
The Impact of service-learning on the training of pre-service teachers: analysis from a physical education subject
2015
This paper discusses the effects of the use of service learning in pre-service teachers (PSTs). This methodology has been applied for two academic years at a Spanish university, providing a direct service for children with special educational needs (SEN) through motor and expressive games. We used Butin's model for the analysis of data collected through written reflections. The results show significant academic and personal learning, especially in areas useful for future teachers. The paper also proposes an extension (subcategories) of the original explanatory model.
Gender differences in technical-tactical behaviour of La Liga Spanish football teams
2021
[Abstract] The aim of this study was to identify differences in technical-tactical behaviour between the men and women first division football teams of the Spanish league, to this end 68 matches corresponding to 2016/17 season were analysed. A comparative analysis of the medians was carried out using the Mann-Whitney U-tests were conducted as post hoc tests. The size effect of this test was calculated and, finally, we performed a grouping of the variables through the clustering bootstrapping technique in both groups. We have detected statistically significant differences (p <0.01) regarding all accurate passes, in favour of men, as well as a greater number of yellow cards. In female footbal…
Aspectos éticos en el proceso de enseñanza: Bullying
2019
Tema 7 sobre el bullying de la asignatura del Grado de Ciencias de la Actividad Física y el Deporte, Metodología de la Enseñanza de la Actividad Física y el Deporte.
A Mixed Methods Study to Examine the Influence of CLIL on Physical Education Lessons: Analysis of Social Interactions and Physical Activity Levels
2020
Physical Education is often selected for applying multilingual initiatives through the use of a content and language integrated learning (CLIL) approach. However, it is still unclear whether the introduction of such an approach might entail losing the essence of physical education and distorting its basic purposes. The aim of this study is to analyze the impact of CLIL on physical education lessons. Given the purpose of this study, a mixed methodological approach based on a sequential exploratory design divided into two different phases is used. We begin with initial qualitative data collection (phase I), consisting of the analysis of interviews with 12 participants (8 teachers and 4 studen…