Neural dynamic sliding mode control of nonlinear systems with both matched and mismatched uncertainties

Mismatched uncertainty and chattering appear as two challenges in sliding mode control. To overcome the problem of mismatched uncertainty, multiple sliding surfaces with virtual inputs are proposed. Accordingly, we have proposed two new methods based on designed neural observer: sliding mode control (SMC) and dynamic sliding mode control (DSMC) methods. Although, the proposed SMC can significantly cope with the mismatched uncertainties, but it suffers from chattering phenomenon. The chattering problem can be removed in DSMC, because an integrator is placed before the system. This results in increased number of the system states. This new state can be identified with the proposed neural observer. Note that in both proposed approaches, the robust performance (invariance property) of system is reserved, even in the presence of mismatch uncertainties. Then, to have a valid comparison the proposed DSMC is also designed using loop transfer recovery observer (LTRO). This comparison shows the good performance of the DSMC based neural networks. Moreover, the upper bound of uncertainties is not used in SMC and DSMC controllers and also in the neural observer and LTRO, which is important in practical implementation. Finally, comparing the equations, one can see the simplicity of DSMC in concept and also in realization.     

Young adult outcomes of the Abecedarian and CARE early childhood educational interventions

Adult benefits for participants in Project CARE were compared with those of the Abecedarian Project, a closely related randomized study of early childhood educational intervention for children from low-income families who were at risk of developmental delays and school failure. CARE replicated Abecedarian's young adult treatment-related educational and vocational attainment gains. CARE data also supported the Abecedarian reduction in marijuana use. Treated individuals in both studies reported adopting a more active life style. The average age at birth of a first child, the number of children, and the proportion of teen parents were positively affected in the Abecedarian sample but not in CARE. Finding significant educational and vocational gains lasting into young adulthood in the CARE study reinforces Abecedarian young adult findings and strengthens the case for early childhood intervention for children from low-income families.     

Creating (in) equalities in access to higher education in the context of structural adjustment and post-adjustment policies: the case of chile

By analyzing the access of different socio-economic groups to post-secondary institutions by quintile, this paper examines the impact produced by higher education financing policies in Chile during the Pinochet (1973–1990), the Aylwin (1990–1994) and the Frei (1994–2000) administrations. To this purpose, CASEN databases and semi-structured interviews conducted with former and current government officials as well as higher education administrators provide valuable information to measure the impact that higher education financing policies had on different socio-economic groups. Access to post-secondary institutions is seen in relation to two aspects: (a) enrollment rates by type of institution and sector and (b) access of students (18–24 year-old group) by family per capita income level. Major conclusion set up that despite increased participation across all socio-economic groups within the post secondary system, upper and upper-middle income students gained access to higher education disproportionately compared to lower, lower-middle, and middle income groups during the 1987–1998 period.

Enrollment projection models for institutional planning

This paper examines alternative techniques for projecting freshman enrollment in specific academic departments. Departmental enrollment projections provided by four different projection models are compared to actual departmental enrollments at a selected institution. Two of the models use only historical data, while the other two models are sensitized to current developments as indicated by the expressed major choices of prospective freshmen. The use of discriminant analysis to establish differential enrollment probabilities is also explored.Although different models do a better job for different curricular departments, the smallest mean squared error across all departments was obtained with the simplest projection technique. The use of the preliminary major choice of prospective freshmen did not improve departmental projections, and the student characteristics explored in this study did not differentiate enrolled from non-enrolled students adequately enough to improve enrollment projection accuracy.Based on the results obtained at this one institution, therefore, it would appear that simple and straightforward projection models can be as useful as complex and sophisticated models.This is an expanded version of an earlier paper read at the 1971 Association of Institutional Research Forum in Denver, Colorado.     

The association between homework and primary school children's academic achievement. International evidence from PIRLS and TIMSS

The association between time devoted to homework and children's academic achievement has long been an issue of great debate. A small number of mainly correlational studies have been conducted into this issue in a primary school setting, but have produced somewhat mixed results. In this paper we contribute to this literature by investigating the relationship between time spent upon homework and children's outcomes across 24 countries. By using a student fixed-effects approach, capturing differences in homework time amongst the same student across different school subjects, we argue that our results are likely to be subject to less confounding than much of the existing literature. We find little evidence that the amount of homework time primary school children are assigned is related to their academic achievement. This holds true across a large number of countries, survives various robustness tests and does not vary by gender or socio-economic status. We interpret this finding as suggesting that the homework assigned to primary school pupils may not be adequate to produce a positive association, and needs be improved if this time-consuming activity is ever going to bring benefits for children's academic achievement.     

Teaching the process of molecular phylogeny and systematics: a multi-part inquiry-based exercise

Three approaches to molecular phylogenetics are demonstrated to biology students as they explore molecular data from Homo sapiens and four related primates. By analyzing DNA sequences, protein sequences, and chromosomal maps, students are repeatedly challenged to develop hypotheses regarding the ancestry of the five species. Although these exercises were designed to supplement and enhance classroom instruction on phylogeny, cladistics, and systematics in the context of a postsecondary majors-level introductory biology course, the activities themselves require very little prior student exposure to these topics. Thus, they are well suited for students in a wide range of educational levels, including a biology class at the secondary level. In implementing this exercise, we have observed measurable gains, both in student comprehension of molecular phylogeny and in their acceptance of modern evolutionary theory. By engaging students in modern phylogenetic activities, these students better understood how biologists are currently using molecular data to develop a more complete picture of the shared ancestry of all living things.     

Critical thinking,executive functions and their potential relationship

The central issue of this paper is to review the possible relationships between the constructs of critical thinking and executive functions. To do this, we first analyse the essential components of critical thinking from a psychological and neurological point of view. Second, we examine the scope of the cognitive and neurological nature of executive functions. Third, we propose a model for comparing or mapping between the most important processes of both constructs. Fourth, we offer some conclusions on the relational path between the two concepts based on the studies reviewed and suggest possible lines of investigation that will undoubtedly facilitate the understanding of shared features and key differences between critical thinking and executive functions.     

A Cross-Cultural Analysis of Organizational Dissent and Workplace Freedom in Five European Economies

Individuals in five European countries—Finland, France, Germany, Spain, and the United Kingdom (n = 1184)—completed a survey exploring the relationship between organizational dissent and workplace freedom of speech. Results revealed workplace freedom of speech is positively correlated with dissent among the entire sample in France and in Germany. Results in Spain were nonsignificant. In the United Kingdom, there was a negative relationship between workplace freedom of speech and dissent. There was a negative relationship between workplace freedom of speech and articulated dissent and a positive relationship with latent dissent in Finland. Moreover, MANCOVA testing showed nationality to have a significant effect on organizational dissent and workplace freedom of speech. Germans scored the highest on dissent and workplace freedom with Spain scoring the lowest.     

An Experimental Analysis of Reading Performance

This experiment was designed to evaluate the validity of S s perceptions of the instructional effectiveness of four different types of black and white and colored illustrations. Each S received a pretest, participated in his respective instructional presentation, received four individual criterial tests, and completed a Visual Illustration Questionnaire. Results indicate that (a) the type of visuals that Ss themselves perceive as being most effective are not always the ones found to be most effective in facilitating their achievement, and (b) all types of visuals are not equally effective in improving Ss achievement of different learning objectives.