A comparison of time-motion and technical–tactical variables between age groups of female judo matches     

Bianca Miarka  Rubiana Cury  Ricardo Julianetti  Rafael Battazza  Ursula Ferreira Julio  Michel Calmet 《Journal of sports sciences》2013,31(16):1529-1538

Abstract

The aim of the study was to verify differences between age groups of female judo matches in time-motion and technical–tactical analysis. The sample was composed of pre-cadet (13–14 years, n = 148), cadet (15–16 years, n = 228), junior (17–19 years, n = 104) and senior (>20 years, n = 237) groups. The time-motion indicators consisted of total combat time, standing combat time, displacement without contact, gripping time, total time of techniques, groundwork combat time and pause time, per match and by each combat/pause cycle. Technical and tactical variables were also collected. The one-way analysis of variance and a post hoc test were conducted, P ≤ 0.05. Cadets, with a median of 7 (2, 12), had a number of combat/pause cycles different from junior, with 3 (1, 8.5). Regarding time-motion per match and per cycle, senior had longer total combat time, standing combat time and gripping time than other groups. Senior presented lower frequency of leg techniques than pre-cadet, cadet and junior. Time-motion and technical–tactical variables effects in female judo athletes emphasise the difference between seniors and other groups.  相似文献   

Does biological sex impact intestinal epithelial injury,small intestine permeability,gastrointestinal symptoms and systemic cytokine profile in response to exertional-heat stress?     

Rhiannon M. J. Snipe  Ricardo J. S. Costa 《Journal of sports sciences》2013,31(24):2827-2835

ABSTRACT

This study aimed to determine the influence of biological sex on intestinal injury, permeability, gastrointestinal symptoms, and systemic cytokine profile in response to exertional-heat stress. Male (n= 13) and eumenorrheic female (n= 11) endurance runners completed 2 h running at 60% V?O_2max in 35°C. Blood samples were collected pre- and post-exercise and during recovery to determine plasma intestinal fatty-acid binding protein (I-FABP) and systemic cytokine profile. Urinary lactulose:L-rhamnose ratio was used to determine small intestine permeability. I-FABP increased 479% pre- to post-exercise (p< 0.001), with no difference between sexes (p= 0.432). No differences between sexes were observed for small intestine permeability (p= 0.808), gut discomfort, total, upper- and lower-gastrointestinal symptoms. However, males reported significantly higher flatulence (p= 0.049) and abdominal stitch (p= 0.025) compared to females. IL-6, IL-8, IL-10 and IL-1ra increased pre- to post-exercise (p< 0.05), with no difference between sexes. However, IL-1β increased post-exercise in males only, and was higher in males compared to females (p= 0.044). Findings suggest that when females are in the follicular phase of the menstrual cycle, biological sex has no effect on intestinal epithelial injury and permeability, and minimal effect on gastrointestinal symptoms and systemic cytokine profile in response to exertional-heat stress.  相似文献   

Competition and diversity in higher education: an empirical approach to specialization patterns of Portuguese institutions     

Pedro Nuno Teixeira  Vera Rocha  Ricardo Biscaia  Margarida Fonseca Cardoso 《Higher Education》2012,63(3):337-352

The expansion of higher education systems has often been associated with the need for increasing diversification, namely at the program level, based on the pressures to adapt more general programmes to a more diverse student population and multiple regional, social, and economic needs. This paper explores empirically the question of programme diversity by drawing on the Portuguese higher education’ experience, which presented massive expansion during the last decades and significant institutional competition in recent years. The study provides a longitudinal approach and analyzes in detail the evolution of diversification and specialization of the public and private sectors, as well as the university and polytechnic subsectors. The analysis aims at helping to illustrate the relevance of analysing diversity from an empirical point of view and its contribution to our understanding of the complex relationships between competition and diversity in contemporary higher education.  相似文献   

Conceptual Problems in the Foundations of Mechanics     

Ricardo Lopes Coelho 《Science & Education》2012,21(9):1337-1356

There has been much research on principles and fundamental concepts of mechanics. Problems concerning the law of inertia, the concepts of force, fictitious force, weight, mass and the distinction between inertial and gravitational mass are addressed in the first part of the present paper. It is argued in the second that the law of inertia is the source of these problems. Consequences drawn from the law explain the metaphysical concept of force, the problematic concept of fictitious force, the nominal definition of weight and the difficulty with defining mass operationally. The core of this connection between the law and these consequences lies in the fact that acceleration is a sufficient condition for force. The experimental basis of the law in the course of its history shows, however, that the law presupposes acceleration necessarily whereas acceleration does not presuppose the law. Therefore, there is no inconvenience in taking acceleration independently of the law. This is enough to bypass those problems. Taking into account how force is measured by force meters and how mass is basically determined, by comparison with the standard mass, a minimal meaning for both concepts of force and mass is established. All this converges with several solutions proposed in the course of history and increases the communicability of mechanics, as outlined in the final part of this paper.  相似文献   

A cross-age study of junior high school students' conceptions of basic astronomy concepts     

Ricardo Trumper 《International Journal of Science Education》2013,35(11):1111-1123

Junior high school students' astronomy conceptions were analysed by means of a written questionnaire presented to them during the beginning of the first semester. The main findings were as follows: almost half of the students indicated that the cause of the day-night cycle is the Earth spinning on its axis; most students chose as their best account for changes in the Moon's phases the Moon moving around the Earth. Despite that, most students thought that the Moon must be in its Full phase for there to be a total solar eclipse; most students underestimated the distances in the Universe and overestimated the Earth's diameter. A great proportion of students indicated that the reason for the different seasons is the tilt of the Earth's axis relative to the plane of its orbit as it revolves around the Sun. But almost the same number of students chose the varying distance between Sun and Earth or between the Earth, Moon and Sun, as a reason for the seasons. Only a third of the students answered correctly that in Israel's latitude, north of the Tropic of Cancer, the Sun is never directly overhead at noon; most students chose the correct estimate of a month for the Moon revolving around the Earth and a year for the Moon going around the Sun; about a third of the students chose the correct answer that when it is noon in Haifa, it would be about sunset in Beijing (90° east of Haifa). Few students indicated that the fact that we always see the same side of the Moon from the Earth implies that the Moon rotates on its axis once a month.  相似文献   

La conducta autopunitiva en el autismo: un nuevo enfoque conductual de tratamiento     

José Luis Marcos  Ricardo Canal 《Infancia y Aprendizaje》2013,36(31-32):173-186

Resumen

En este trabajo se investigan dos procedimientos de reducción de las conductas autopunitivas que frecuentemente presentan los niños autistas. El primer procedimiento consiste en el reforzamiento de respuestas incompatibles con estas conductas, lográndose así una franca disminución en su frecuencia. El segundo procedimiento parte del supuesto (comprobado en el análisis conductual) que las autopuniciones representan una respuesta de escape ante la ansiedad generada por determinadas situaciones; de este modo, el procedimiento va encaminado a la reducción, o eliminación, de esta ansiedad situacional mediante la técnica de la desensibilización sistemática «in vivo», dando como resultado la eliminación total de las conductas autopunitivas ante estas situaciones, y a más largo plazo, su erradicación del repertorio conductual del sujeto.  相似文献   

Nature and profiles of racial prejudice: analyses and educational implications in Secondary School students / Naturaleza y perfiles del prejuicio racial: análisis e implicaciones educativas en alumnos de Educación Secundaria     

Ricardo Cuevas  Onofre Contreras  Tomás García-Calvo  Juan-Carlos Pastor 《Infancia y Aprendizaje》2013,36(2):248-277

Abstract

The reduction of racial prejudice is an important challenge of intercultural education. Thus, the aim of this study was to analyze racial prejudice, as well as the different profiles and the possible educational implications in secondary school students. A total of 327 third form students completed the scales of blatant and subtle prejudice and also a scale of emotions towards North Africans. The results showed significant levels of subtle prejudice and four profiles of racial prejudice, with a low number of students showing equalitarian tendencies. A multivariate analysis showed significant differences in prejudice depending on social distance as well as the academic level of the participants’ families. Finally, we discuss the results from the perspective of intercultural education and we suggest some lines of intervention in order to promote the integration of students from different cultures.  相似文献   

Tiny noise,big mistakes: adversarial perturbations induce errors in brain–computer interface spellers     

Xiao Zhang  Dongrui Wu  Lieyun Ding  Hanbin Luo  Chin-Teng Lin  Tzyy-Ping Jung  Ricardo Chavarriaga 《国家科学评论(英文版)》2021,8(4)

An electroencephalogram (EEG)-based brain–computer interface (BCI) speller allows a user to input text to a computer by thought. It is particularly useful to severely disabled individuals, e.g. amyotrophic lateral sclerosis patients, who have no other effective means of communication with another person or a computer. Most studies so far focused on making EEG-based BCI spellers faster and more reliable; however, few have considered their security. This study, for the first time, shows that P300 and steady-state visual evoked potential BCI spellers are very vulnerable, i.e. they can be severely attacked by adversarial perturbations, which are too tiny to be noticed when added to EEG signals, but can mislead the spellers to spell anything the attacker wants. The consequence could range from merely user frustration to severe misdiagnosis in clinical applications. We hope our research can attract more attention to the security of EEG-based BCI spellers, and more broadly, EEG-based BCIs, which has received little attention before.  相似文献   

The role of executive functions in the relation between socioeconomic level and the development of reading and maths skills / El rol de las funciones ejecutivas en la relación entre el nivel socioeconómico y el desarrollo de habilidades lectoras y matemáticas     

José-Pablo Escobar  Ricardo Rosas-Díaz  Francisco Ceric  Andrés Aparicio  Paulina Arango  Rodrigo Arroyo 《Cultura y Educación》2018,30(2):368-392

Executive functions (EF) are a set of processes that allow individuals to plan, monitor and organize tasks and thus play a key role in the development of reading and maths skills. Environmental factors such as socioeconomic level (SEL) influence reading and maths skills as well as EFs. The aim of this study is to explore the extent to which executive functions play a mediating role between SEL and reading and maths performance. To this end, we assessed 286 Chilean primary education students: 86 with a high SEL and 200 with a low level. The results show that the high-SEL group obtained consistently higher scores than their peers with low SEL levels in both reading and maths tasks as well as in EF measurements. This suggests that SEL could influence the development of these variables. The results also showed that EFs partially mediate the relation between SEL and reading and maths skills in primary school students through the specific function of inhibition. The results are discussed in light of the effect of SEL on the development of EFs and school learning.  相似文献   

A Longitudinal Study of Physics Students' Conceptions on Energy in Pre-Service Training for High School Teachers     

Trumper  Ricardo 《Journal of Science Education and Technology》1998,7(4):311-318

Journal of Science Education and Technology - How physics students teachers' understanding of energy develops during their pre-service high school teacher university program? How do their...  相似文献