Construct validity of self-concept in TIMSS’s student background questionnaire: a test of separation and conflation of cognitive and affective dimensions of self-concept among Saudi eighth graders

The aims of this study are to: (a) assess if cognitive self-concept (competence) and affective self-concept in mathematics and science are different constructs, (b) evaluate the construct validity of self-concept in the context of conflation and separation, and (c) test if the relationships among cognitive and affective variables are invariant across gender. The data for this study were obtained from the Trends in International Mathematics and Science Study 2007 database. Data about 2,687 out of 4,099 eighth grade Saudi students were subject to various analyses. The variables used in this study were mathematics and science self-concepts, and mathematics and science subject value as part of the Students Background Questionnaire. The relationships among constructs were examined with the use of SPSS16 and the structural equation modeling software, AMOS16. The results demonstrated that subject value and self-concept were different constructs. Also, the results demonstrated that cognitive and affective self-concepts were independent, but strongly related constructs, and the structure of the construct was clearer when self-concept was separated into cognitive and affective components than when it was conflated. The relationships among cognitive, affective, and subject value in mathematics and science were invariant across gender. However, their relationships with achievement were not invariant across gender.     

Knee extensor and flexor torque development with concentric and eccentric isokinetic training

This study assessed muscular torque and rate of torque development following concentric (CON) or eccentric (ECC) isokinetic training. Thirty-eight women were randomly assigned to either CON or ECC training groups. Training consisted of knee extension and flexion of the nondominant leg three times per week for 20 weeks (SD = 1). Eccentric training increased ECC knee extension and flexion peak torque more than CON training. The ECC group improved acceleration time and time to peak torque with ECC movements versus the CON group. Slow-velocity ECC isokinetic training yielded greater ECC and similar CON torque development gains versus CON training over the course of 20 weeks in young women.     

Frequency-coordinate vector diagram

From the standpoint of circuit synthesis as well as for a fundamental comprehension of circuit behavior, it is desirable to be able to visualize the response of a circuit over an extended frequency range by means of a geometrical construction. Mathematically, the response of a circuit can be expressed with the La Place transform theory as a function of the complex frequency variable, p = α + jωw, in which a is the decrement and ω is the “real” angular frequency. Physically, the nature of the real-frequency response is usually not discernible by casual inspection of the mathematical function. This paper develops a means of visualizing this frequency response readily through the construction of a vector diagram from the response function.