Cracking her codes: understanding shared technology resources as positioning artifacts for power and status in CSCL environments

There is a positive relationship between student participation in computer-supported collaborative learning (CSCL) environments and improved complex problem-solving strategies, increased learning gains, higher engagement in the thinking of their peers, and an enthusiastic disposition toward groupwork. However, student participation varies from group to group, even in contexts where students and teachers have had extensive training in working together. In this study, we use positioning theory and interaction analysis to conceptualize and investigate relationships between student interactions across two partner pairs working with technology in an all-female cryptography summer camp and their negotiated positions of power and status. The analysis resulted in uneven participation patterns, unequal status orderings, and an imbalance of power in both comparison cases. We found a reflexive relationship between partner interactions around shared technology resources and negotiated positions of power and status, which leads us to conclude that interactions around technology function as an important indicator of negotiated positionings of power and status in CSCL settings, and vice-versa. With that said, we found qualitative differences in the ways emergent status problems impacted each team’s productivity with the cryptography challenge, which has important implications for future research on CSCL settings and classroom practice.     

Response rate techniques for zirconia-based Nernstian oxygen sensors

Several techniques are described to determine the rate of response of electrodes used in Nernstian sensors to oxygen concentration changes in various environments. These techniques are related to combustion control and automotive applications as well as laboratory testing of electrodes. The response behaviour of the electrodes used in the SIRO₂ low temperature sensor has been characterized and comparison made with several other electrodes used conventionally in oxygen sensors.     

A dilatometric study of the solubility of U4O9 in UO2

Phase relationships in the system UO₂-O₉ were studied using a dilatometei in which the O/U ratio of a UU_2+x specimen could be both controlled and measured. Phase boundary temperatures were indicated by changes in expansion or contraction rate during heating or cooling, respectively. The solubility of U₄O₉ in UO₂ agreed with the results of previous workers using other techniques. The dependence of solubility on temperature is complex, and appears to be influenced by a high-temperature phase transition in U₄0₉.     

Further Notes for Predicting Shielding Effectiveness for the Plane Shield Case

The problem of the electromagnetic shielding effectiveness of an electrically thin, nonmagnetic, plane metal sheet of infinite extent on the electromagnetic field generated by a circular loop field source with uniform current I is solved by application of the quasi-near field approximations to the exact integral expressions. The results are shown to be in excellent agreement with experimental data as well as numerical integration results.     

A colorimetric technique for assessing the mixture quality of fine particle mixtures

As part of a containing study of the mixing of cohesive powders, late/pigment mixtures were created using either a pestle and mortar or a Lödige mixer.The fine pigment particle `coat' the coarser talc particles, and as the pigment is progressively distributed, so the colour changes.Electron microscopy failed to reveal significant variation in pigment distribution, but comparison of the samples using a KCSIS spectrophotometer gave a satisfactory quantitative assessment of mixture quality.     

Some aspects of numerical simulation for Lamb wave propagation in composite laminates

Some aspects of numerical simulation of Lamb wave propagation in composite laminates using the finite element models with explicit dynamic analysis are addressed in this study. To correctly and efficiently describe the guided-wave excited/received by piezoelectric actuators/sensors, effective models of surface-bounded flat PZT disks based on effective force, moment and displacement are developed. Different finite element models for Lamb wave excitation, collection and propagation in isotropic plate and quasi-isotropic laminated composite are evaluated using continuum elements (3-D solid element) and structural elements (3-D shell element), to elaborate the validity and versatility of the proposed actuator/sensor models.     

Mood and HIV risk behavior among drug-dependent veterans.

Extends prior investigations of risk behaviors for contracting and transmitting the human immunodeficiency virus (HIV) among treatment-seeking drug abusers by analyzing the relationship between HIV risk behavior and drug use and psychopathology variables. A battery of tests related to knowledge about AIDS and semistructured interviews were administered to 170 patients (aged 21–59 yrs) at a Veterans Administration drug dependence treatment unit. Ss with high anxiety and depression scores reported engaging in significantly more HIV drug-risk behaviors. In terms of drug of choice, polydrug users did not report engaging in significantly more high-risk sexual behaviors than Ss abusing solely cocaine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)