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Abstract-A 9.4 Tesla superconducting magnet is designed and fabricated with a warm bore of 800 mm for neuroscience research. The superconducting magnet will be made of a NbTi Wire-in-Channel (WIC) conductor with a higher ratio of copper to non-copper, which thus sustains the high stresses. It is cooled to operate temperature at 4.2 K liquid helium. The cryostat system is cooled through GM cryocoolers, some used to cool the radiation shield, and the others realize the re-condensed liquid helium. The MRI magnet system has a high level of stored energy, about 134 MJ, and a relatively-lower nominal current, about 212.5 A. The magnet will be operated in a persistent current mode with a superconducting switch. The WIC wires are employed to meet the cryostability criteria to avoid any risks from quench. The protection circuit with the subdivision of the coil reduces the terminate voltage and hot-spot temperature. In the paper, the specifications of magnet system will be presented.Index Terms-Metabolism imaging, MRI superconducting magnet, passive shield, sub-division quench protection.

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Measurements of the velocity profile of HeII forced flow within a square cross-section channel are reported. The particle image velocimetry (PIV) technique is used for these measurements with micron scale solid deuterium particles as tracers of the HeII velocity field. Steady state velocity profiles at different bath temperatures clearly show the existence of a turbulent boundary layer in HeII forced flow. These observed velocity profiles are in reasonable agreement with correlations based on measurements in classical fluids.

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It has been argued that item response theory trait estimates should be used in analyses rather than number right (NR) or summated scale (SS) scores. Thissen and Orlando postulated that IRT scaling tends to produce trait estimates that are linearly related to the underlying trait being measured. Therefore, IRT trait estimates can be more useful than summated scores when examining relationships between test scores and external variables. Also, when the model holds, IRT trait estimates possess an interval scale that is a property assumed for dependent variables by most statistical procedures used in educational research. The objective of this study was to use Monte Carlo methods to compare the performance of IRT trait estimates and SS scores in predicting outcome variables in the context of health and behavioral assessment. The use of scores based on the graded-response model versus summated scores was compared. Results indicated that IRT-based scores and summated scores are comparable when evaluating the relationships between test scores and outcome measures. Thus, applied researchers could use summated scores in predictive studies and circumvent evaluating the assumptions underlying use of IRT-based scores.