The effect of scopolamine on reference and working memory in pigeons

A comparison of the effects of scopolamine hydrobromide on working memory and reference memory in White Carneaux pigeons was undertaken by means of a modified delayed matching-to-sample procedure. Performance on working-memory trials was disrupted by decreases in sample duration and intertriai interval and by increases in delay interval. Performance on reference memory trials was not disrupted by any of these parametric manipulations. In Experiment 1, the pigeons received injections of scopolamine hydrobromide (0.01, 0.05, or 0.1 mg/kg), scopolamine methyl bromide (0.1 mg/kg), or saline prior to test sessions. In Experiment 2, the pigeons received injections of scopolamine hydrobromide (0.01 or 0.03 mg/kg), scopolamine methyl bromide (0.03 mg/kg), or saline. In both experiments, scopolamine hydrobromide had greater disruptive effects on working-memory trials than on reference-memory trials. The centrally active form of scopolamine disrupted working-memory trial accuracy more than the peripherally active form. However, no drug dose × delay interval interaction was obtained. Thus, the interference on working-memory-trial accuracy produced by central cholinergic blockade would not appear to be due to alterations in the active maintenance of information during the delay interval.     

“Sense of place” and college placement

It is generally assumed that young people with lower socioeconomic status (SES) face restricted access to higher education institutions, and particularly to those which are considered to be more prestigious. Differences in student placement in higher education institutions by place of residence are usually explained by their SES. We argue that place of residence is not only a geographical attribute, but also a social factor that influences self-identity and plays a significant role in student placement regardless of their SES. The study was conducted in Israel among first year undergraduate students, and analyzed the effect of living in four residential locality types (cities, small towns, Jewish and Arab villages) on institutional placement. The study focused on the patterns of student placement in institutions, controlling for individual SES and previous academic ability. Findings indicate that place of residence has a net effect on student placement, and it interacts with SES and with previous academic achievements. Less “successful” students, regardless of their SES, are less influenced by their residential locality. These differences in college placement are explained in part by the place of residence, which represents a way of life that creates a shared “sense of place” or “habitus” based on locality.     

A simple model for the hysteretic elastic shear modulus of unsaturated soils

Considering the great importance of the elastic shear modulus G₀ of unsaturated soils to the serviceability of many geo-structures in geo-energy and geo-environmental engineering, some semi-empirical models have been reported for the G₀ of unsaturated soils. Existing models require at least three parameters and the calibration of the model parameters requires extensive time-consuming unsaturated soil tests. In this study, a simple semi-empirical model is proposed for the hysteretic G₀ of unsaturated soils, requiring only two parameters. The constitutive variables of the mean Bishop’s stress and a bonding variable are adopted for considering the average stress between soil particles and the additional normal forces between soil particles provided by water menisci. The derived equation is applied to simulate the G₀ of unsaturated silts and sands. Comparisons between the measured and calculated results demonstrate that the proposed equation is able to describe the influences of various factors on G₀, including mean net stress, suction, wetting-drying, and void ratio.     

Development of reflection through learning activity

What kind of developmental potential is present in elementary schoolchildren but hindered by the traditional type of education? Half a century ago Daniel El’konin and Vasili Davydov, the leaders of Russian Vygotskian educational psychology started answering this question. They suggested thatreflection is a basic human ability and it can be developed in younger students. Reflection includes thinking about one’s own actions and thoughts, taking other people’s point of view, and understanding oneself. In this paper I present results of the design experiments conducted in Russian schools that deliberately promote students’ reflection. In these schools the majority of children achieve high levels of reflection previously attributed only to the gifted students. One aspect of reflection will be given special attention, the ability of the student to take the perspective of another person. The comparative microanalysis of learning discourse in the first and the fourth grades demonstrated a significant growth of this ability through the first three years of schooling and made evident limitations imposed by the existing structure of the classroom cooperation. The long-term effects of education based on the principles of learning activity are demonstrated on the basis of the recent PISA study data.     

Investigation on Crystallization Kinetics of Zr-AI-Based Bulk Amorphous Alloys

Zr65Al10Ni10Cu15, Zr52.5Al10Ni10Cu15Be12.5 and Zr52.5Al10Ni14.6 Cu17.9Ti5bulk amorphous alloys were prepared by copper mould casting. The crystallization kinetics was measured by differential scanning calorimeter(DSC) with different heating rates, and the activation energy was calculated using Kissinger equation. The relationship between thermal stability and rate constant of crystallization reaction is discussed on the view of crystallization kinetics, and the effect of small atom Beryllium on thermal stability of bulk amorphous alloys is also studied.     

Drawing Parallels in Search of Educational Equity: A Multicultural Education Delegation to China Looks Outside to See Within

In 2004, a professional delegation of multicultural educators visited the People's Republic of China to explore how diversity issues are addressed and how students are prepared for entry into the international workforce. The delegation, sponsored by the People to People Ambassador Programs, observed numerous parallels to the American system of education, including the challenge of providing equity for students of minority cultures, especially those in poor rural areas, and the conflict between modernization and preservation of cultural heritage.