Plastic deformation and fracture of binary TiAl-base alloys

The mechanical behavior of binary TiAl alloys containing 46 to 60 at. pct Al has been studied in bulk materials preparedvia rapid solidification processing. Bending and tensile tests were carried out at room temperature as a function of Al concentration. A few alloys were also tested from liquid nitrogen temperature to ∼ 1000°C. Deformation substructures were studied by analytical transmission electron microscopy and fracture modes by scanning electron microscopy (SEM). It was found that both microstructure and composition strongly affect the mechanical behavior of TiAl-base alloys. A duplex structure, which contains both primary y grains and transformedγ/α ₂ lamellar grains, is more deformable than a single-phase or a fully transformed structure. The highest plasticities are observed in duplex alloys containing 48–50 at. pct Al after heat treatment in the center of theγ + α phase field. The deformation of these duplex alloys is facilitated by 1/2[110] slip and {111} twinning, but very limited superdislocation slip occurs. The twin deformation is suggested to result from a lowered stacking fault energy due to oxygen depletion or an intrinsic change in chemical bonding. Other factors, such as grain size and grain boundary chemistry and structure, are important from a fracture point of view. The results on the deformation and fracture modes as a function of test temperature are also discussed.     

Mentoring relationships of New Zealand nurses: an empirical study (Part 1)

A national, random, postal survey (n = 298) of mentoring behaviour among New Zealand nurses was undertaken. The initial research problem was to seek an explanation for the apparent lack of mentoring in New Zealand nursing. However, as the study evolved the lack of agreement concerning the definition of mentoring became a major research obstacle. A new conceptual framework of mentoring grounded in the work of Kathy Kram (1985) was devised. A quantitative global measure of mentoring behaviour (the TMS score) was used to measure levels of mentoring behaviour. This score was used as the dependent variable in subsequent statistical tests of: the definitional hypothesis-the study's validity check; the peer mentoring hypothesis which explored selected dynamics of mentor protégé relationships, and four allied research questions. The conceptual framework and approach are discussed in part one.     

Implementing software metrics — the critical success factors

This paper reviews the current state of industry with regard to the introduction of software metrics. It discusses the benefits that organizations have derived from metrication, it looks at why organizations have sought to introduce metrics programmes, how they have gone about introducing those programmes and the problems that they have encountered during implementation. The review found that, on the whole, only the sanitized aspects of metrics experiences have actually been published. This seems to be especially the case with respect to practitioner resistance. Very few organizations admit to having encountered resistance during the introduction of a metrics programme. The paper also includes the results of a pilot study, conducted by the first author, which examines the attitudes that developers hold towards the introduction of software metrics. The key findings of this pilot study are that positive attitudes to metrics correlate highly with levels of education and to job satisfaction.     

Negative priming in associative learning: Evidence from a serial-conditioning procedure.

Three experiments investigated the suggestion that a predicted or primed stimulus commands less processing and consequently elicits a weaker CR than a stimulus that is not primed. In each experiment rats received initial training in which the presentation of each of 2 serial compounds, A-X and B-Y, was followed by the delivery of food. Subsequently, X's capacity to elicit the CR, approaching the site of food delivery, was assessed when X was preceded by Stimulus A (i.e., primed) or was presented after Stimulus B. Stimulus X elicited a more vigorous response when it was presented after B than when it followed A. These results show that the ability of one event to elicit its CR is reduced if its presentation has been predicted by some other event. This negative priming effect supports one aspect of A. R. Wagner's (1981) model of Pavlovian conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serum amyloid P component scintigraphy and turnover studies for diagnosis and quantitative monitoring of AA amyloidosis in juvenile rheumatoid arthritis

OBJECTIVE: To evaluate aspects of the natural history of AA amyloidosis complicating juvenile rheumatoid arthritis (JRA), and its response to therapy with chlorambucil. METHODS: Scintigraphy and 7-day turnover studies were performed in JRA patients with histologically proven (n = 35) or clinically suspected (n = 30) AA amyloidosis, following intravenous injection of 123I and 125I-labeled serum amyloid P component (SAP). Prospective monitoring studies were performed over 2-3 years in 20 patients with amyloidosis. All but 2 amyloidosis patients were treated with chlorambucil. RESULTS: Positive scanning results were obtained in all patients in whom imaging was performed within 12 years of positive biopsy findings of amyloid and in 5 patients with clinically suspected amyloidosis. Negative scanning results with normal SAP metabolism, indicating regression of amyloid, were obtained in 4 patients whose amyloidosis had been in full clinical remission for more than 12 years. Prospective monitoring studies in patients whose JRA-associated inflammatory activity was in remission demonstrated regression of amyloid in 8 patients and no substantial changes in 8 others; however, in 4 further patients with active inflammation, there was accumulation of amyloid. There was a very poor correlation between the amount of amyloid present at a particular site and the resultant organ dysfunction. CONCLUSION: Radiolabeled SAP scintigraphy and turnover studies are useful complementary tools in the diagnosis, screening, and quantitative monitoring of type AA amyloidosis in JRA. The amyloid deposits may progress and/or regress at different rates in different anatomic sites over short periods.     

The science-industry interface: Correlation of time series of indicators and their spectra,and growth models in the nuclear fuels industry

This paper is the third in a series on the flows of influence at the interface between geoscience research and the exploration for and mining of nuclear fuels. It deals with the application of signal processing methods to research and industry indicators, with emphasis on time and frequency domain correlations and lags, and on growth modelling of the indicators using the special and general logistic models. The findings include the following: there was a strong interchange across the science-industry interface; quantitative methods can establish the degree of correlation and the time periods in which these correlations mainly reside; also the timing of decisions to initiate exploration and research can be specified in this case. A strategy of applying quantitative methods, history of science, and periodic analyses of the state of the industry to studies of science policy is suggested by this research.     

Excited-state-absorption cross sections and amplifier modeling inthe 1300-nm region for Nd-doped glasses

The performance of Nd³⁺-doped fibre amplifiers is limited by strong excited-state absorption (ESA) of the signal, and, even for fluorozirconate glasses, ESA prevents the important region below 1320 nm from being used. To quantify this limitation and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate fiber-amplifier model to provide the first quantitative comparisons of performance for Nd³⁺ -doped glasses in the 1300-nm band as a function of host