The use of TEPC for reference dosimetry.

The radiation fields on board aircraft are quite complex and cover an energy range that is unusual in ordinary radiation protection work. Usually dosemeters measure only one radiation quality and the mixture found on board makes measurements complicated. There is also some doubt when it comes to the best choice of quantity for this application and no radiation standards exist for this kind of radiation field. For those reasons there is a need to find a standard measurement procedure that could serve as a reference for other, maybe simpler, measurements or for calculations of route doses. The only direct reading dosemeter that both measures the absorbed dose to tissue and the radiation quality (in terms of lineal energy) is the tissue-equivalent proportional counter (TEPC). The instrument was originally developed for scientific purposes and is still used as such. The detector consists of a gas filled cavity surrounded by a few mm thick wall. Both wall and gas consists of tissue-like material. The measurement principles are explained. Results observed with TEPC instruments are demonstrated. A preliminary collection of data reported by different groups from measurements on board aircraft will be shown. The results agree within +/- 20%. The conclusion is that TEPC instruments have the capacity of serving as reference instruments.     

Componential modeling of alternative strategies for performing spatial tasks.

Tested single-strategy and strategy-shifting models in a stratified random sample of 30 male high schoolers and undergraduates to explore relations among aptitude, spatial task solution strategy, and task performance. Results show that different models fit different Ss on each of 3 task steps (encoding, synthesis, and comparison), suggesting that different Ss used different strategies for solving the same items. Some of the best fitting models specified that Ss frequently and flexibly switch strategies in keeping with variations in item demands (a form of adaptive, within-task learning). For the encoding and synthesis steps, significant performance differences were found among Ss using different strategies. Aptitude may have affected strategy choice. Evidence for 2 types of strategy shifting (route and sequence shifting) was found. The shift models help explain individual differences in problem-solving processes employed in complex tasks such as the ones administered in this study. The strategy-shift models are appended. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for order of operations in the acquisition and transfer of sequential cognitive skills.

The authors report a series of experiments in which questions about the nature of memory for the order of processing operations in sequential processing skills (i.e., skills that require proper sequencing of a set of component operations) were addressed. Evidence from 3 studies of a sequential number computation skill suggested that memory for processing sequences that are general to many instances is more instrumental than sequence memory that is instance specific. Results generalized over task versions that differed markedly in the number of processing sequences and the number of unique stimulus instances per sequences. General sequence memory appeared to develop relatively early in practice and to underlie errors in transfer that resembled einstellung effects. The findings are discussed with respect to memory mechanisms postulated in recent theories of skill acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The field dependence–independence construct: Some, one, or none.

Measured the field dependence–independence construct using tests of perception of the upright such as the rod-and-frame test and tests of cognitive restructuring such as the Hidden Figures Test. The relationship between cognitive restructuring and perception of the upright was investigated. 241 high school seniors received 34 tests, including 12 measures of field dependence–independence. Analysis of the data, using multidimensional scaling, cluster analysis, and factor analysis, resulted in 5 dimensions, including 2 associated with the field dependence–independence measures. One of the field dependence–independence dimensions measured cognitive restructuring; the other, which was related to perception of the upright, was labeled Familiar Field and was postulated to measure strategy selection in familiar situations. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rasch measurement in developing faculty ratings of students applying to graduate school

The Standardized Letter of Recommendation (SLR), a 28-item form, was created by ETS to supplement the qualitative rating of graduate school applicants' nonacademic qualities with a quantitative approach. The purpose of this study was to evaluate the following psychometric properties of the SLR using the Rasch rating scale model: dimensionality, reliability, item quality, and rating category effectiveness. Principal component and factor analyses were also conducted to examine the dimensionality of the SLR. Results revealed (a) two secondary factors underlay the data, along with a strong higher order factor, (b) item and person separation reliabilities were high, (c) noncognitive items tended to elicit higher endorsements than did cognitive items, and (d) a 5-point Likert scale functioned effectively. The psychometric properties of the SLR support the use of a composite score when reporting SLR scores and the utility of the SLR in higher education and in admissions.     

Customizing User Interaction in Smart Phones

Emerging input modalities could facilitate more efficient user interactions with mobile devices. An end-user customization tool based on user-defined context-action rules lets users specify personal, multimodal interaction with smart phones and external appliances. The tool's input modalities include sensor-based, user-trainable free-form gestures; pointing with radio frequency tags; and implicit inputs based on such things as sensors, the Bluetooth environment, and phone platform events. The tool enables user-defined functionality through a blackboard-based context framework enhanced to manage the rule-based application control. Test results on a prototype implemented on a smart phone with real context sources show that rule-based customization helps end users efficiently customize their smart phones and use novel input modalities.     

Production of 2-[18F]Fluoro-2-deoxy-D-glucose at the Laboratory of Radiochemistry, University of Helsinki

Production 2-[^{1 8}F]fluoro-2-deoxy-D-glucose ([^{1 8}F]FDG) was started at the Laboratory of Radiochemistry in 1998 when a cyclotron, specially designed for the production of short-lived positron emitters, was bought to the laboratory. The radiosynthesis of [^{1 8}F]FDG is based on aminopolyether-mediated nucleophilic fluorination. [^{1 8}F]Fluoride is produced by the ^{1 8}O(p,n)^{1 8}F nuclear reaction. [^{1 8}F]FDG is synthesised with an automated device. The radiochemical yield of the synthesis is 50% (by the end of bombardment). Sterile and isotonic [^{1 8}F]FDG solution is produced within 55 min. [^{1 8}F]FDG is delivered for patient use by the medical company MAP Medical Technologies.     

Effects of aptitudes, strategy training, and task facets on spatial task performance.

A pilot study, with 8 high school students, demonstrated that 3 item characteristics accounted for most of the variation in item difficulty in a paper-folding task: number of folds, number of obscured folds, and number of asymmetric folds. Retrospective reports suggested that Ss employed 2 strategies when attempting to solve these items: a visualization strategy and an analytic strategy. In the main experiment, these 2 strategies were demonstrated via motion picture models; 24 Ss received visualization training, and 24 received analytic training. Training effects of the demonstration films were compared with a performance feedback condition given to 8 Ss. All Ss performed 74 paper-folding items and 60 surface development transfer items following treatment. Error and latency data suggested that the treatments affected strategy selection and efficiency on both tasks. Treatment effects depended on item characteristics and response mode as well as on Ss' fluid-analytic/visualization and verbal abilities, as assessed by the Concept Mastery Test, WAIS Vocabulary test, and Raven Progressive Matrices. Sex differences were also noted, with verbal ability being important in the performance of females but not males. Implications for a process theory of human abilities are discussed. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)