Eye movements of monkeys during performance of ambiguous cue problems

Learning & Behavior - Eye movements of four stumptailed monkeys were measured during performance of simple and ambiguous form discriminations. Duration of fixations increased during learning of...     

Effect of vitamin E supplementation on oxidative stress in hemodialysis patients

Hemodialysis represents a chronic stress status for its recipients. Many hypotheses state that this may be associated with oxidative stress. Thus, there may be deficiency of antioxidants like erythrocytic superoxide dismutase, catalase, vitamin E or increased generation of free radicals like superoxide anions. A study was carried out to investigate oxidant and antioxidant status in chronic renal failure patients undergoing hemodialysis and effect of vitamin E supplementation on these two status. Blood samples were collected from patients before and after hemodialysis and from controls. The samples were analyzed for quantitation of MDA as index of lipid peroxide, nitric oxide, vitamin E, vitamin C and enzymatic antioxidants namely erythrocyte SOD and catalase. As compared to controls, the levels of serum MDA were significantly increased and activities of erythrocyte SOD and catalase, levels of serum nitric oxide, serum vitamin E and plasma vitamin C were significantly decreased both before and after hemodialysis. The efficiency of vitamin E therapy in hemodialysis patients was assessed by re-evaluating oxidant and antioxidant status of same patients after supplementation of vitamin E. Vitamin E supplementation caused decrease in serum MDA and increase in levels of serum nitric oxide, vitamin E, vitamin C and activities of erythrocytic SOD and catalase. Our results suggest the presence of oxidative stress and the possible preventive role of vitamin E therapy in hemodialysis patients.     

Analyzing imbalance among homogeneous index servers in a web search system

The performance of parallel query processing in a cluster of index servers is crucial for modern web search systems. In such a scenario, the response time basically depends on the execution time of the slowest server to generate a partial ranked answer. Previous approaches investigate performance issues in this context using simulation, analytical modeling, experimentation, or a combination of them. Nevertheless, these approaches simply assume balanced execution times among homogeneous servers (by uniformly distributing the document collection among them, for instance)—a scenario that we did not observe in our experimentation. On the contrary, we found that even with a balanced distribution of the document collection among index servers, correlations between the frequency of a term in the query log and the size of its corresponding inverted list lead to imbalances in query execution times at these same servers, because these correlations affect disk caching behavior. Further, the relative sizes of the main memory at each server (with regard to disk space usage) and the number of servers participating in the parallel query processing also affect imbalance of local query execution times. These are relevant findings that have not been reported before and that, we understand, are of interest to the research community.     

Identifying students with learning disabilities: the effect of implementing statewide guidelines

Methods for identifying students with learning disabilities continue to be an area of controversy. The present investigation examined the impact of implementing statewide guidelines for the identification of these students. Data were collected from multidisciplinary team reports on 718 students with learning disabilities who were referred and labeled during the 1983-84 school year (before implementation of statewide learning disability guidelines) and 790 students who were identified during 1987-88 (after implementation of the guidelines). The results of the study revealed that the statewide guidelines significantly changed the characteristics of students who were identified. After the implementation of the guidelines, students with much more severe academic problems were identified. These students were much more likely to have a severe discrepancy and be chronically failing in the regular classroom. However, even with explicit, widely accepted guidelines, approximately one third of all students identified in 1987-88 failed to meet the stated criteria for identification. The implications of these findings for professional practice and future research are discussed.     

A Summer Academic Research Experience for Disadvantaged Youth

Internships are an effective way of connecting high school students in a meaningful manner to the sciences. Disadvantaged minorities have fewer opportunities to participate in internships, and are underrepresented in both science, technology, engineering, and mathematics majors and careers. We have developed a Summer Academic Research Experience (SARE) program that provides an enriching academic internship to underrepresented youth. Our program has shown that to have a successful internship for these disadvantaged youth, several issues need to be addressed in addition to scientific mentoring. We have found that it is necessary to remediate and/or fortify basic academic skills for students to be successful. In addition, students need to be actively coached in the development of professional skills, habits, and attitudes necessary for success in the workplace. With all these factors in place, these youths can become better students, compete on a more level playing field in their internships, and increase their potential of participating actively in the sciences in the future.     

Wishes of fourth-through seventh-grade gifted students

Three wishes and primary wishes of fourth- through seventh-grade gifted students participating in a residential program for the gifted were collected and categorized. The results indicated that males wished for material things more often than did females. With the exception of fourth graders, subjects made altruistic wishes more frequently than any other wish.     

Infantilism

The aim of this article is to define and operationalize the construct of infantilism.

The methods of theoretical research involve analysis and synthesis. Age and content criteria are analyzed for childhood and adulthood. Infantile traits in an adult are described.

Results. The characteristics of adult infantilism in the modern world are defined, taking into account increasing information flows and socio-economic changes. The concept of “infantilism” and its main features are defined as an organization of the personality that includes traits and behavioral models that are typical of one's earlier age periods and not appropriate to the person's actual age, which is most articulately manifested in emotional and volitional immaturity of an individual.

Scientific novelty. The main psychological characteristics of adulthood are described, including reflection, the desire to work and have a vocation, vocational self-determination, work skills, the desire for self-realization, and emotional and volitional maturity. Objective characteristics of adulthood are: transition to economic and territorial independence of the parental family, and development of new social roles, such as that of worker, spouse, and parent. Two possible operationalizations of the concept are identified: objective (existence/absence in a person’s life of objective criteria of adulthood) and subjective (self-report on the subjective feeling of existence/absence of the psychological characteristics of adulthood).

The practical significance of the work consists in formulation of an operationalization of “infantilism,” which at the moment has so many interpretations. Such operationalization is necessary for further analysis and research.