Self-selected or imposed exercise? A different approach for affective comparisons

The aim of this study was to compare the psychological and physiological responses of self-selected and imposed sessions of equivalent intensities and durations and allowing to participants a free control of pace during the self-selected session. Seventeen participants completed three sessions on a cycle ergometer. Participant’s VO_2Peak and lactate threshold were measured during an incremental exercise test. During the second and third sessions, participants could view a virtual cyclist on a monitor. During the self-selected session, participants were allowed free control of the intensity and duration. To ensure that the imposed session replicated the self-selected session in intensity, participants were instructed to follow an additional virtual cyclist, which was displayed on a monitor using the CompuTrainer 3D software. Power output and physiological and psychological variables were recorded during the sessions. A two-way ANOVA showed no effect of condition for power output (P = 0.940), heart rate (HR) (P = 0.965), VO₂ (P = 0.898), blood lactate (P = 0.667), Feeling Scale (P = 0.877), Felt Arousal Scale (P = 0.924) and CR100 (P = 0.939). A paired t-test showed no significant difference in Physical Activity Enjoyment Scale scores between sessions (P = 0.054). In contrast to previous studies, the self-selected session did not provide better affective responses than the imposed session with same intensity and duration.     

Hegemonic and counter-hegemonic discourses in science education scholarship from the perspective of post-critical curricular theories

Cultural Studies of Science Education - Although in-depth educational reviews can be carried out building on curricular theories, the appropriation of this knowledge by science education...     

Curriculum translation and environmental education: considering issues of discursive intentionality, interpretation, and validity

We would like to thank our commentators Reis, Ercikan and Alper for their insightful comments on our research study and respond in brief to a few of their criticisms. More specifically, we would like to address what we consider to be the three main issues they raise with regard to the practices of curriculum translation and implementation across languages, namely viewing speakers’ intentions as a mode of signification in discourse analysis, exploring curriculum translation through an interpretive research approach, and establishing the validity of research on curriculum translation.

Concept or computation: Students' understanding of the mean

In statistics, and in everyday life as well, the arithmetic mean is a frequently used average. The present study reports data from interviews in which students attempted to solve problems involving the appropriate weighting and combining of means into an overall mean. While mathematically unsophisticated college students can easily compute the mean of a group of numbers, our results indicate that a surprisingly large proportion of them do not understand the concept of the weighted mean. When asked to calculate the overall mean, most subjects answered with the simple, or unweighted, mean of the two means given in the problem, even though these two means were from different-sized groups of scores. For many subjects, computing the simple mean was not merely the easiest or most obvious way to initially attack the problem; it was the only method they had available. Most did not seem to consider why the simple mean might or might not be the correct response, nor did they have any feeling for what their results represented. For many students, dealing with the mean is a computational rather than a conceptual act. Knowledge of the mean seems to begin and end with an impoverished computational formula. The pedagogical message is clear: Learning a computational formula is a poor substitute for gaining an understanding of the basic underlying concept.Research support: Research reported in this paper was supported by NSF research award No. SED78-22043 in the Joint National Institute of Education-National Science Foundation Program of Research on Cognitive Processes and the Structure of Knowledge in Science and Mathematics.     

Deafness and attention in deaf children

The study shows the differences between hearing parents and deaf instructors interacting with deaf children and directing their attention. Data were collected at home and at a service for special needs in Bristol, England. The mother or instructor was asked to play naturally with the child with the toys provided. When the child's attention was focused during their play, the mother or instructor had to try to direct the child's attention to each of the toys. The results suggest that both groups (mothers and instructors) were effective in directing attention to objects not in the immediate area of play; however, hearing mothers were more successful than deaf instructors.     

Tuning direct current streaming dielectrophoresis of proteins

Dielectrophoresis (DEP) of biomolecules has large potential to serve as a novel selectivity parameter for bioanalytical methods such as (pre)concentration, fractionation, and separation. However, in contrast to well-characterized biological cells and (nano)particles, the mechanism of protein DEP is poorly understood, limiting bioanalytical applications for proteins. Here, we demonstrate a detailed investigation of factors influencing DEP of diagnostically relevant immunoglobulin G (IgG) molecules using insulator-based DEP (iDEP) under DC conditions. We found that the pH range in which concentration of IgG due to streaming iDEP occurs without aggregate formation matches the pH range suitable for immunoreactions. Numerical simulations of the electrokinetic factors pertaining to DEP streaming in this range further suggested that the protein charge and electroosmotic flow significantly influence iDEP streaming. These predictions are in accordance with the experimentally observed pH-dependent iDEP streaming profiles as well as the determined IgG molecular properties. Moreover, we observed a transition in the streaming behavior caused by a change from positive to negative DEP induced through micelle formation for the first time experimentally, which is in excellent qualitative agreement with numerical simulations. Our study thus relates molecular immunoglobulin properties to observed iDEP, which will be useful for the future development of protein (pre)concentration or separation methods based on DEP.     

Output-feedback binary adaptive control of MIMO systems using monitoring function

The problem of adaptive control design for multivariable linear time-invariant plants with unknown control direction is considered. A solution is proposed based on the SDU factorization of the high frequency gain matrix (HFG) and the monitoring function approach. The adaptation scheme is the binary model reference adaptive control (BMRAC) which utilizes parameter projection and sufficiently high adaptation gains. The signs of the leading principal minors of the HFG define the control directions, and the lack of knowledge of which is a major challenge in the multivariable framework. The role of the monitoring function is to monitor the output error transient and then provide the necessary changes of the adaptation gain signs to guarantee a stable adaptive control. In addition to proving the signal boundedness of the resulting closed-loop system, the output tracking error is shown to be asymptotically as well as exponentially practically stable, i.e., exponentially stable with respect to a small residual compact set of size inversely proportional to the BMRAC adaptation gain. The latter implies good transient properties of the output tracking error in contrast to conventional adaptive laws which only guarantee asymptotic stability but can lead to extremely slow error convergence. The extension of the proposed approach to matched disturbances is also briefly discussed following the classical paradigm of disturbance estimators. Numerical results with a visual servoing application illustrate the efficiency of the proposed method.     

“Who polluted the Potomac?” The translation and implementation of a US environmental story in Brazilian and Turkish classrooms

In this study we examine how elementary teachers in Brazil and Turkey approached the translation and subsequent classroom implementation of an instructional activity that promotes environmental awareness through a combination of student role playing and teacher oral delivery of an environmental story about river pollution. A discourse analysis showed that translation into Portuguese was literal, an approach that fostered a classroom implementation that emphasized detached transmission of knowledge (the teacher frequently interrupted her delivery to provide textual, contextual and recontextualizing information to students). In contrast, translation into Turkish was free, that is, with many modifications that led to a decontextualized and detached text. Implementation of this text was focused on the creation of student involvement, being dominated by oral strategies such as religious analogies (heaven and hell), and parallel repetitions of statements of shared guilt. Based on these findings, it was concluded that neither translation promoted an equivalent form of environmental instruction (i.e., involved transmission of environmental knowledge). Furthermore, an argument is made that effective translation requires that original and translated curricula foster analogous levels of involvement (or detachment) as well as equivalent forms of classroom relationships and social roles (pragmatic equivalence).