A new ordered phase in the AlPd system

Using electron diffraction and electron microscopy a new phase has been observed in a rapidly solidified Al-6%Pd alloy. Depending on the cooling rate this phase is present in the as quenched cellular-dentritic structure along the cell boundaries or in finer precipitates mostly along the domain boundaries of the fcc solid solution. In both cases the precipitates agglomerate and grow to bigger size after heating in the electron microscope. The new phase having a complicated structure and a large unit cell is closely related to the Al₄Mn phase which is hexagonal.     

Diagnosis and surgical treatment of cystlike lesions of the equine paranasal sinuses

Development of cysts in the equine paranasal sinuses is probably a congenital disease; however, signs may not appear for several years. In 4 cases, clinical signs were observed when fluid accumulation within the cysts resulted in nasal discharge or facial swelling, or when secondary infection occurred. Treatment required surgical removal of the lining membrane and other involved tissues. Postoperative care included lavage of the sinuses and systemic antibiotic therapy.     

The effects of devitrification on the mechanical properties of Cu46Zr54 metallic glass

The room temperature mechanical properties of the metallic glass Cu₄₆Zr₅₄ have been investigated as a function of aging time at 375°C (15°C belowT _g). The results indicate that the tensile fracture stress and hardness of this material can be changed by such thermal processing. Fracture stress and hardness are increased with short times at temperature by structural relaxation. Also, the presence of a very small volume fraction of crystalline phase causes the shear stiffness of the material to increase markedly providing an additional increase in fracture stress and hardness. Continued devitrification causes embrittlement and the decrease of fracture stress, as predicted by the model of two-phase materials; however, hardness continues to increase, reflecting the increasing volume fraction of the harder crystalline phases. Embrittlement and decreasing fracture stress are enhanced by the stress concentration effect at the crystallites which causes void formation and growth. ROBERT L. FREED formerly with the Department of Materials Science and Engineering, MIT     

An analysis of students�� gaming behaviors in an intelligent tutoring system: predictors and impacts

Students who exploit properties of an instructional system to make progress while avoiding learning are said to be ??gaming?? the system. In order to investigate what causes gaming and how it impacts students, we analyzed log data from two Intelligent Tutoring Systems (ITS). The primary analyses focused on six college physics classes using the Andes ITS for homework and test preparation, starting with the research question: What is a better predictor of gaming, problem or student? To address this question, we developed a computational gaming detector for automatically labeling the Andes data, and applied several data mining techniques, including machine learning of Bayesian network parameters. Contrary to some prior findings, the analyses indicated that student was a better predictor of gaming than problem. This result was surprising, so we tested and confirmed it with log data from a second ITS (the Algebra Cognitive Tutor) and population (high school students). Given that student was more predictive of gaming than problem, subsequent analyses focused on how students gamed and in turn benefited (or not) from instructional features of the environment, as well as how gaming in general influenced problem solving and learning outcomes.     

Hydrogen atom cleaning of archeological artefacts

For the development of H⁺ and H⁰ beams a new method has been developed based on the expansion of a cascade arc plasma. A partial aim was to develop an intense beam of atomic hydrogen. The result was a 100 A equivalent hydrogen atom beam with an energy conversion efficiency of typically 30–40%. The resulting hydrogen plasma has also been used to do preliminary experiments on restoration treatment of archeological artefacts according to the method of Vep ek et al. The present high density atom rich plasma beam with < 0.4 eV energies and temperatures proved to be effective in the treatment of these artefacts. The treated artefacts showed good erosion resistance compared to untreated as well as conventionally treated samples, notwithstanding the short treatment time of 20 minutes at a temperature of 400°C and the provisional character of the trial experiment.     

Two-year behavior outcomes of project towards no tobacco use.

Presents a 2-year follow-up data from a school-based tobacco use prevention project designed to test the effectiveness of 3 primary components in social influence programs. The components either teach refusal skills, awareness of social value misperceptions, or physical consequences. Curricula were tested with a randomized experiment involving 48 junior high schools. Data suggested that a physical-consequences curriculum is successful at attenuating increases in adolescent smokeless tobacco use, cigarette experimentation may be attenuated by various approaches, and a comprehensive program with all 3 components was necessary to attenuate increases in weekly use of both forms of tobacco. These results also indicate that school-based tobacco use interventions can be effective at least 2 years postprogram, after students make their transition to high school. (PsycINFO Database Record (c) 2010 APA, all rights reserved)