Comparing the roles of 3D representations in audio and audio-visual collaborations

This study investigates the effects of performance and communication within audio-visual (shared representations) and audio-only conditions. Two three-dimensional (3D) representations were presented in each communication condition. The goal of the study was to examine both explicit and implicit references made during verbal interactions, and to gather subjective usability evaluations of each representation. Sixty dyads performed a series of problem solving tasks in three experimental conditions: mixed, 3D cylinder and 3D helix representations. Assessment measures included overall performance time and accuracy, and user attitudes pertaining to the usability of the displays. Although no differences in task performance were observed, qualitative measures revealed differences between representation and communication groups. User preferences for 3D cylinder and 3D helix representations were observed, with disparate strategies being adopted between groups. In general, the analyses indicated that the presence of shared visual information enhances collaborative problem solving.     

Interactive drawing of the left ventricular borders from cine magnetic resonance images

The calculation of the left ventricular (LV) function requires the endocardial and epicardial contours of the cavity to be accurately defined beforehand. This identification is generally achieved by manual tracing of the LV borders. Such manual methods are tedious and time-consuming, limiting their clinical usefulness for cardiac quantitative analysis. The purpose of this study was to evaluate an efficient method for drawing the LV borders from magnetic resonance (MR) images. This technique, based on the use of cubic B-spline curves to modelize the shape of the cavity, allows an interactive and real-time remodeling of the contours. The variability and the accuracy of this contour tracing tool have been evaluated on standard cine-MR images obtained in 10 healthy volunteers in a short-axis view. Theendocardial and epicardial areas and themean local error between the contours were compared through interobserver and intraobserver analyses. A good correlation was observed between the enclosed areas in both studies (r>0.98 for endocardium,r=0.99 for epicardium). The mean local error between the contours was less than 2.8% for the endocardial borders and less than 1.4% for the epicardial borders. This method has a high degree of flexibility for the interactive trace and deformation of contours. Although further validation is needed, this method may prove useful in clinical application to permit the measurement of LV function from MR imaging.Address for correspondence: Departement de Radiologie, Hôpital Cardiovasculaire et Pneumologique, BP Lyon Montchat, 69394 Lyon Cedex 03, France. Additional reprints of this chapter may be obtained from the Reprints Department, Chapman & Hall, One Penn Plaza, New York, NY 10119.     

A Rapid and Robust Diagnostic for Liver Fibrosis Using a Multichannel Polymer Sensor Array

Liver disease is the fifth most common cause of premature death in the Western world, with the irreversible damage caused by fibrosis, and ultimately cirrhosis, a primary driver of mortality. Early detection of fibrosis would facilitate treatment of the underlying liver disease to limit progression. Unfortunately, most cases of liver disease are diagnosed late, with current strategies reliant on invasive biopsy or fragile lab‐based antibody technologies. A robust, fully synthetic fluorescent‐polymer sensor array is reported, which, rapidly (in 45 minutes), detects liver fibrosis from low‐volume serum samples with clinically relevant specificity and accuracy, using an easily readable diagnostic output. The simplicity, rapidity, and robustness of this method make it a promising platform for point‐of‐care diagnostics for detecting and monitoring liver disease.     

Grain growth behaviour on reheating Al–Nb-containing steel in the homogenised condition

ABSTRACT

Grain size development during reheating is important to the mechanical properties of steels, and non-uniform grain growth including abnormal and bimodal grain growth are undesirable for steel manufacturing. In this paper, reheating treatments for Al–Nb-containing steel (0.057?wt-% Al and 0.019?wt-% Nb) were selected based on Thermo-Calc predictions for the dissolution temperatures of precipitates in the steel for a fully homogenised condition. Abnormal grain growth occurred in the homogenised Al–Nb sample during reheating, associated with random dissolution of the grain boundary-pinning AlN precipitates, while bimodal grain growth was not observed. So material in a homogenised condition would not be expected to provide a fully uniform grain structure during reheating treatment.     

Behaviour of pathogenic and indicator bacteria during urban wastewater treatment and sludge composting, as revealed by quantitative PCR

Two enteric pathogens, Salmonella spp. and Campylobacter jejuni, and two bacteria commonly used as indicators, Escherichia coli and Clostridium perfringens, were monitored using quantitative real-time PCR during municipal wastewater treatment and sludge composting. The results were compared with those obtained using standard culture methods. A reduction of all bacteria was observed during wastewater treatment and during the thermophilic phase of composting. However, the bacterial groups studied behaved differently during the process, and the main differences were observed during biological treatment in activated sludge basins. In particular, Salmonella spp. and C. jejuni survived better during activated sludge treatment than E. coli. C. jejuni was the most resistant to wastewater treatment among the four bacterial groups. Overall, differences in survival were observed for all bacteria studied, when submitted to the same environmental pressure. This holds both for differences between indicators and pathogenic bacteria and between pathogenic bacteria. These results show the difficulty in defining reliable indicators.     

Atmospheric pressure chemical vapour deposition of SnSe and SnSe2 thin films on glass

Atmospheric pressure chemical vapour deposition of tin monoselenide and tin diselenide films on glass substrate was achieved by reaction of diethyl selenide with tin tetrachloride at 350–650 °C. X-ray diffraction showed that all the films were crystalline and matched the reported pattern for SnSe and/or SnSe₂. Wavelength dispersive analysis by X-rays show a variable Sn:Se ratio from 1:1 to 1:2 depending on conditions. The deposition temperature, flow rates and position on the substrate determined whether mixed SnSe–SnSe₂, pure SnSe or pure SnSe₂ thin films could be obtained. SnSe films were obtained at 650 °C with a SnCl₄ to Et₂Se ratio greater than 10. The SnSe films were silver–black in appearance and adhesive. SnSe₂ films were obtained at 600–650 °C they had a black appearance and were composed of 10 to 80 μm sized adherent crystals. Films of SnSe only 100 nm thick showed complete absorbtion at 300–1100 nm.     

Tumour cell toxicity of intracellular hyperthermia mediated by magnetic nanoparticles

Intracellular hyperthermia is a process by which malignant cells can be selectively killed by heat generated by nanomediators located inside the cell. Here we show that maghemite anionic nanoparticles are efficiently captured by human prostatic tumor cells (PC3) and concentrate within intracellular vesicles. When submitted to an alternative magnetic field, maghemite nanocrystals generate heat from the cell inside, inducing a temperature elevation of eight degree in a loose pellet of 20 million magnetically labeled cells. We demonstrate that this heating modality was as lethal as external waterbath heating. A one hour AC magnetic field (700 kHz-31 mT) exposure of the magnetically labeled cells killed 44% of the cells. Interestingly, more than 80% of the cells were killed after being submitted twice to the magnetic field. Finally, when magnetic cells coexist with non magnetic ones, the same proportions of cells were damaged for both populations, after magnetic field exposure. These findings pave the way for an efficient cell killing mediated by intracellular magnetic hyperthermia.