An evaluation of the social perspective in the development oftechnical requirements

Uses a qualitative methodology to examine how discourse norms and socialization processes affect the development of technical requirements. Our exploratory investigation of how government personnel develop and review technical requirements indicates that discourse norms and academic technical writing socialization processes affect the technical writing process. Technical writers perceived that requirements in work statements became less precise as more requirements were coordinated in team-based designs. In essence, we found that, in team-based designs, interpretation conflict and technical diffusion were important dimensions when writing and coordinating technical requirements. Our findings suggest that collaborative technical writing is a complex and difficult process in team-based designs where integration and persuasion skills dominate     

The effectiveness of producer‐side machine‐independent optimizations for mobile code

Portable mobile code is often executed by a host virtual machine using just‐in‐time compilation. In this context, the compilation time in the host virtual machine is critical. This compilation time can be reduced if optimizations are performed ahead‐of‐time before distribution of the mobile code. Unfortunately, the portable nature of mobile code limits ahead‐of‐time optimizations to those that are machine‐independent. This work examines the effect of machine‐independent optimizations on the performance of mobile code applications. All experiments use the SafeTSA Format, a mobile code format that is based on Static Single Assignment Form (SSA Form). The experiments, which are performed on both the PowerPC and IA32 architectures, indicate that the effects of performing classical machine‐independent optimizations are—in fact—quite machine‐dependent. Nevertheless, the results demonstrate that applying such optimizations in a mobile code system can be beneficial. Copyright © 2009 John Wiley & Sons, Ltd.     

Diffusion-controlled smoulder propagation in a composite slab

The steady propagation of a thin smouldering front parallel to the faces of a composite reactive slab has been considered. The slab consists of a double layer of solid with differing densities. As the smouldering front progresses into the solid it leaves behind an inert porous medium through which oxidizer is able to diffuse to the front. It is assumed that the reactive solid is sufficiently dense for no oxidizer to be present. The oxidizer concentration on one face of the slab is specified, the other being impervious to the transport of reactants. Dimensionless equations and boundary conditions are obtained for the concentration of oxidizer in the porous medium. These are solved to first order by use of a complex-variable method and a hodograph transformation giving the shape of the smouldering front for various parameter combinations. The analysis is extended to the case where the layers are of unequal thickness. Simple expressions for the shape of the front and the oxidizer concentration are obtained when one layer thickness is large. The model here considered is a first step in a more comprehensive analysis of smouldering in a non-uniform medium.     

The RHIC zero degree calorimeters

The RHIC zero degree calorimeters provide common event characterization in the four heavy ion experiments which recently completed their first data taking run. Here we describe simulations which lead to the design of these devices, testbeam performance and initial experience at RHIC.     

Treatment of unresectable hepatocellular carcinoma with lipiodol chemoembolization: a multicenter randomized trial. Groupe CHC

We investigated the effect of successive administrations of SA4503 (1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride), a novel cognitive enhancer with high affinity and selectivity for the sigma1 receptor subtype, on the cortical cholinergic dysfunction-induced impairment of the spatial learning performance in the Morris water maze (MWM) task in rats. The impairment of the spatial learning performance was produced by the ibotenic acid-induced lesion of the basal forebrain (BF) area in rats. Escape latencies to find the platform during the training trials of the MWM task were significantly prolonged in the BF-lesioned rats compared with the sham-operated rats. Daily treatment with SA4503 (0.1-0.5 mg/kg, P.O./day) for 13 days ameliorated this learning deficit. In the probe trial, BF-lesioned rats reduced the number of times each rat crossed the former platform location during the training trials (goal area) in comparison with sham-operated rats. Successive administrations of SA4503 (0.25 mg/kg, P.O./day) also significantly increased the BF lesion-induced reduction of the number of times each rat crossed the goal area. These results suggest that the successive administrations of SA4503 attenuate the impairment of the spatial learning performance in rats with cortical cholinergic dysfunction, and that SA4503 is useful as a therapeutic drug for Alzheimer's disease.     

A nonlinear spatially variant object-dependent system model forprediction of partial volume effects and scatter in PET

Accurate quantitation of small lesions with positron emission tomography (PET) requires correction for the partial volume effect. Traditional methods that use Gaussian models of the PET system were found to be insufficient. A new approach that models the non-Gaussian object-dependent scatter was developed. The model consists of eight simple functions with a total of 24 parameters. Images of line and disk sources in circular and elliptical cylinders, and an anthropomorphic chest phantom were used to determine the parameter values. Empirical rules to determine these parameter values for various objects based on those for a reference object, a 21.5-cm circular cylinder, were also proposed. For seven spheroids and a 3.4-cm cylinder, pixel values predicted by the model were compared with the measured values. The model-to-measurement-ratio was 1.03±0.07 near the center of the spheroids and 0.99±0.03 near the center of the 3.4-cm cylinder. In comparison, the standard single Gaussian model had corresponding ratios of 1.27±0.09 and 1.24±0.03, respectively, and the corresponding ratios for a double Gaussian model were 1.13±0.09 and 1.05±0.01. Scatter fraction (28.5%) for a line source in the 21.5-cm cylinder was correctly estimated by our model. Because of scatter. The authors found that errors in the measurement of activity in spheroids with diameters from 0.6 to 3.4 cm were more significant than previously appreciated