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   

Counseling Latina/o Students From an Ecological Perspective: Working With Peter     

Alison Cerezo  Maya E. O'Neil  Benedict T. McWhirter 《Journal of College Counseling》2009,12(2):170-181

This case study describes the experiences of a Mexican American college student addressing difficulties with academic motivation and social adjustment to college. The authors present a counseling intervention that is ecologically focused and designed to help the student develop critical consciousness regarding ethnic and social class identity.  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   

An adaptive mechanism for Moodle based on automatic detection of learning styles     

Ioannis Karagiannis  Maya Satratzemi 《Education and Information Technologies》2018,23(3):1331-1357

This paper proposes an automatic approach that detects students’ learning styles in order to provide adaptive courses in Moodle. This approach is based on students’ responses to the ILS and the analysis of their interaction behavior within Moodle by applying a data mining technique. In conjunction to this, an adaptive mechanism that was implemented in Moodle is presented. This adaptive mechanism builds the user model based mainly on the proposed approach for automatic detection of learning styles in order to adapt the presentation and the proposed navigation to students’ different learning styles and educational objectives. An evaluation study was conducted to evaluate the proposed approach for automatic detection of learning styles and the effect of the adaptive mechanism. Two groups of students were formed, namely the experimental and the control. The first had access to a Moodle course that automatically detected their learning styles and exploited the adaptive mechanism, whilst the second had access to the standard version of a Moodle course. The results were promising since they indicated that our proposed approach for automatic detection of learning styles attained adequate precision compared to other works, even though the patterns considered are less complex. Additionally, the results indicated that the adaptive mechanism positively affected students’ motivation and performance.  相似文献   

Plasma proteinase inhibitory activity in ectopic and molar pregnancy     

Maya Roche  V. P. Arun Kumar  S. M. Ibrahim  K. Nalini 《Indian journal of clinical biochemistry : IJCB》2008,23(4):352-355

Antitryptic, antichymotryptic and alpha 2- macroglobulin activities were measured in sera of normal nonpregnant and normal pregnant women and women with tubal ectopic pregnancy and molar pregnancies in the first 5 to 7 weeks of pregnancy calculated from the last menstrual period. While alpha 2-macroglobulin decreased in early normal pregnancy compared to nonpregnant state (p<0.001), in ectopic and molar pregnancies there was an increase in alpha 2- macroglobulin activity (p < 0.001), as compared to nonpregnant and normal pregnant women. Antitryptic activity did not increase in normal and ectopic pregnancy, however was increased in molar pregnancy (p < 0.01). Antichymotryptic activities did not show a change either in normal pregnancy or in cases of ectopic and molar pregnancy. Drop in alpha 2- macroglobulin activity to near normal levels in ectopic, 6 weeks post surgery, correlated well with the decrease in β-hCG. However, in molar pregnancy, alpha 2- macroglobulin remained elevated even when the β-hCG levels in serum returned to zero 10 weeks after surgery. The studies suggest a major role for circulating proteinase inhibitors especially alpha 2-macroglobulin in regulating proteinase activity in normal, ectopic and molar pregnancy.  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