Relation between teachers' early expectations and students' later perceived competence in physical education classes: Autonomy-supportive climate as a moderator.

The purpose of this study was to explore whether, in naturalistic physical education classes, the relation between teachers' early expectations and students' later perceived competence was moderated by the extent to which the motivational climate created by the teachers was autonomy supportive. Using a 1-year longitudinal design, data were obtained from 421 students and 22 teachers from 10 French junior high schools. Multilevel analyses revealed that (a) teachers' early expectations were related to students' later perceived competence, particularly when these expectations were positive, and (b) this relation was stronger when the classroom motivational climate was low in autonomy support. Implications for future research and educational practices are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of limiting steps for efficient trans-activation of HIV-1 promoter by Tat in Saccharomyces cerevisiae

Cellular context is an important determinant for the activity of Tat, the trans-activator of human immunodeficiency virus (HIV). We have investigated HIV-1 promoter expression and trans-activation in Saccharomyces cerevisiae to provide clues about the limiting steps for Tat activity in this organism. A minimal 43-nucleotide HIV promoter (HIV43) has the activity of a weak yeast promoter in the presence or absence of various enhancer binding sites (bs), whereas the entire long terminal repeat is not expressed. None of these constructs could be trans-activated by Tat. Fusion proteins Gal4 binding domain (BD)-Tat48 and Gal4BD-Tat72 are active with different efficiencies on various yeast promoters that have Gal4 bs. They have 70 and 50% of Gal4 wild type activity on hybrid HIV promoters fused to Gal4 bs only in the presence of AP1 bs. This study shows that trans-activation of the HIV-1 promoter by Tat occurs in yeast when Tat is targeted to the promoter and a functional enhancer activity is present. Sp1 function and Tat transfer from the RNA to the promoter are two major elements for in vivo trans-activation of HIV-1 that are defective in S. cerevisiae but can be replaced by functional equivalents.     

Stage specificity, dose response, and doubling dose for mouse minisatellite germ-line mutation induced by acute radiation

Germ-line mutation induction at mouse minisatellite loci by acute irradiation with x-rays was studied at premeiotic and postmeiotic stages of spermatogenesis. An elevated paternal mutation rate was found after irradiation of premeiotic spermatogonia and stem cells, whereas the frequency of minisatellite mutation after postmeiotic irradiation of spermatids was similar to that in control litters. In contrast, paternal irradiation did not affect the maternal mutation rate. A linear dose-response curve for paternal mutation induced at premeiotic stages was found, with a doubling dose of 0.33 Gy, a value close to those obtained in mice after acute spermatogonia irradiation using other systems for mutation detection. High frequencies of spontaneous and induced mutations at minisatellite loci allow mutation induction to be evaluated at low doses of exposure in very small population samples, which currently makes minisatellite DNA the most powerful tool for monitoring radiation-induced germ-line mutation.     

On the use of a formal requirements engineering language: The Generalized Railroad Crossing Problem

In this paper, we report on the use of theAlbert II requirements specification language through the handling of the Generalized Railroad Crossing case study. This formal language is based on an ontology of concepts used for capturing requirements inherent in real-time, distributed systems. Because of itsnaturalness, the language supports a direct mapping of customers’ informal needs onto formal statements, without having to introduce artificial elements. The language is founded on a formal framework (real-time temporal logic) which supports the reasoning process of the analyst during the elaboration of the specification. Such support for the reasoning is illustrated in the context of a goal-oriented approach adopted for the elaboration of the case study.     

Evaluating the Effectiveness of Using Flexography Printing for Manufacturing Catalyst‐Coated Membranes for Fuel Cells

This study is an evaluation of the effectiveness of the flexography printing process for manufacturing catalyst‐coated membranes (CCMs) for use in proton exchange membrane fuel cells (PEMFCs). Flexography is a maskless and continuous process that is used in large‐scale production with water‐based inks to reduce the cost of production of PEMFC components. Unfortunately, water has undesirable effects on the Nafion® membrane: water wets the membrane surface poorly and causes the membrane to bulge outwards significantly. Membrane printability was improved by pre‐treating membrane samples by water immersion for short periods (<2 min). This pre‐treatment was used to control the membrane deformation before printing to limit the impact of the ink transfer. Water and ink drop deposition experiments were performed to estimate the liquid‐air‐Nafion® apparent contact angle and the locally induced membrane deformation. Despite the short immersion times used in the tests, the immersion pre‐treatment appeared to induce structural modifications that enhanced both the membrane wettability and the dimensional stability. Flexography printability tests were performed on these treated membranes and showed that the dimensional instability of the Nafion® membrane was the critical parameter for limiting the ink transfer. The immersion pre‐treatment improved the printability of the Nafion® membranes, which were used to fabricate cathodes that were tested in an operational fuel cell.     

Spatial characterization of process variations via MOS transistortime constants in VLSI and WSI

This paper is the first large-scale experimental characterization of spatial process variations for a parameter that is directly involved in timing issues: the MOS transistor time constant. This is achieved by measuring the oscillation period of highspeed (500 MHz) CMOS ring oscillators that are implemented at different locations on individual dies and over wafers. Novel phenomena are observed, improving our understanding of how process variations affect the performance of synchronous systems, particularly in clock distribution networks. We observed four components contributing to period variations: an environment-dependent component, a process-dependent component of lower spatial frequency, a random component analogous to white noise, and a component depending on the geometry of the power-supply distribution network     

Aqueous corrosion of lanthanum aluminosilicate glasses: influence of inorganic anions

In order to confine specific long-life actinides, originating from high-level nuclear wastes, lanthanum aluminosilicate glasses are considered. The aqueous corrosion behavior of these glasses is studied under static conditions (T=96 °C, duration between one and six months, glass surface area/leachate volume, S/V=0.3, 50 and 500 cm⁻¹) by means of solution analysis (ICP-MS and spectrophotometry) and solid analysis (X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry). Tests performed at high S/V ratio lead to silicon releases of 10⁻³ mol l⁻¹ while lanthanum releases reach 10^−4.5 mol l⁻¹. Phosphate anions are found to modify the dissolution, as an amorphous lanthanide phosphate is evidenced at the glass surface after the corrosion experiment. The lanthanide releases decrease in presence of phosphate, but the matrix dissolution process is not reduced.     

Rotating instability in the vaneless diffuser of a radial flow pump

The paper refers to the behavior of a vaneless diffuser of a radial flow pump in partial flow operating conditions. Some experimental data have been obtained using 2D/2C PIV and unsteady pressure measurements within the diffuser, in various operating conditions. The experimental results at the lower flow rate are compared with two-dimensional numerical calculations.