Exploring the Effects of Financial Aid on the Gap in Student Dropout Risks by Income Level

Using national survey data and discrete-time logit modeling, this research seeks to understand whether student aid mediates the relationship between parental income and student dropout behavior. Our analysis confirms that there is a gap in dropout rates for low-income students compared with their upper income peers, and suggests that some types of aid are associated with lower risks of dropout. Thus, we examine the interaction between financial aid type and parental income to explore whether, and if so how, different types of aid may reduce the dropout gap by income level group. We find that the receipt of a Pell grant is related to narrowing the dropout gap between students from low- and middle-income groups, although overall the interaction between Pell grant and income is not significant. Loans and work-study aid both have similar effects on student dropout across all income groups. Methodologically, our results demonstrate the need to model dropout behavior temporally and to avoid main-effect bias by incorporating interaction effects.

School experience,relational justice and legitimation of institutional

This study analysis the relationship between perceptions of the justice of teacher’ behaviour and (a) the legitimation of school authority and (b) the legitimation of institutional authorities outside school. 448 adolescent students participated in the study. In questionnaire participants were asked about (a) perceptions of the justice of teachers’ behaviour; (b) evaluation of the school experience; and (c) evaluation of institutional authorities. Results show that the evaluation of the justice of teacher behaviour, in particular relational and procedural justice, have an impact on the legitimation of the authority of teachers and on the evaluation of institutional authorities outside school. Results also show that the legitimacy granted to teachers is a mediator variable between perceptions of justice in school and evaluation of authorities outside school. These results are discussed in the context of the studies on the relationship between school experience and adolescents attitudes towards authorities, and in the framework of the “Relational Model of Authority” and of the “Group Value Model”.     

Developing Seventh Grade Students’ Understanding of Complex Environmental Problems with Systems Tools and Representations: a Quasi-experimental Study

A systems-based classroom intervention on environmental education was designed for seventh grade students; the results were evaluated to see its impact on the development of systems thinking skills and standard science achievement and whether the systems approach is a more effective way to teach environmental issues that are dynamic and complex. A quasi-experimental methodology was used to compare performances of the participants in various dimensions, including systems thinking skills, competence in dynamic environmental problem solving and success in science achievement tests. The same pre-, post- and delayed tests were used with both the comparison and experimental groups in the same public middle school in Istanbul. Classroom activities designed for the comparison group (N = 20) followed the directives of the Science and Technology Curriculum, while the experimental group (N = 22) covered the same subject matter through activities benefiting from systems tools and representations such as behaviour over time graphs, causal loop diagrams, stock-flow structures and hands-on dynamic modelling. After a one-month systems-based instruction, the experimental group demonstrated significantly better systems thinking and dynamic environmental problem solving skills. Achievement in dynamic problem solving was found to be relatively stable over time. However, standard science achievement did not improve at all. This paper focuses on the quantitative analysis of the results, the weaknesses of the curriculum and educational implications.     

Adaptive synchronization of chaotic Colpitts circuits against parameter mismatches and channel distortions

In this work, synchronization of chaotic Colpitts circuits, using adaptive controllers to combat circuit parameter mismatches and channel distortions, is studied by numerical simulations. Synchronization errors caused by different main circuit components are compared, and compensation for time-constant and time-varying circuit parameter mismatches is demonstrated. Different kinds of channel distortions, including time-constant and time-varying channel attenuation, Additive White Gaussian Noise (AWGN) are all investigated by numerical simulations and discussed. Simulation results indicated that the synchronization performance of chaotic Colpitts circuits can be greatly improved by applying adaptive controllers when parameter mismatches and channel attenuation are considered as time-constant or time-varying, but have no obvious enhancements regarding the effect on AWGN channel.     

Child care in Kenya

Kenya—East African nation of big game, tourism, thorn trees, and white sand beaches—is facing a new challenge in preschool education. With nearly 20 percent of the children under five in some type of child care situation, it is possible that everyday preschool experiences may be leading children either closer to, or away from, the values of their parents. The test for this relatively new nation is to find the proper balance between the goals of the preschool and the values of both traditional and modernized parents. It is a topic of equal importance in any nation where a great many preschoolers are cared for by persons other than their parents.     

Simple model for gas holdup and liquid velocity of annular photocatalytic external-loop airlift reactor under both bubble and developing slug flow

Based on the momentum conservation approach, a theoretical model was developed to predict the superficial liquid velocity, and a correlation equation was established to calculate the gas holdup of an annular external- loop airlift reactor(AELAR)in the bubble flow and developing slug flow pattern. Experiments were performed by using tap-water and silicone oil with the viscosity of 2.0 mm²/s(2cs-SiO)and 5.0 mm²/s(5cs-SiO)as liquid phases. The effects of liquid viscosity and flow pattern on the AELAR performance were investigated. The predictions of the proposed model were in good agreement with the experimental results of the AELAR. In addition, the comparison of the experimental results shows that the proposed model has good accuracy and could be used to predict the gas holdup and liquid velocity of an AELAR operating in bubble and developing flow pattern.     

Nobel Prize in Physics 2006

The discovery of the cosmic microwave background radiation in 1965 was a defining moment in the history of cosmology — the science that deals with the universe as a whole, its origin, evolution and future. This discovery was recognized with Nobel Prizes to Penzias and Wilson in 1978. The Nobel Prize in Physics for 2006 further acknowledged the importance of the study of this background radiation. The precise measurement of the spectrum of this radiation and its variation across the sky have helped our understanding of the evolution of structures in the universe. This article explains these discoveries and their importance. T Padmanabhan is a professor at IUCAA, Pune. He is interested in all aspects of theoretical physics, and especially in those in which gravity plays a role.