From expert-driven to user-oriented communication of infection control guidelines

Currently, infection control guidelines in hospitals and other health care institutions are more expert-driven than user-oriented. In order to enhance the usability of the expert-driven guideline format, we developed a website for the communication of existing guidelines that better fit the practical information needs of health care workers (HCWs). We employed a user-centered design process that involved two studies.In the initial study, 28 HCWs were asked to solve tasks using existing, paper-based infection control guidelines. In order to detect their strategies and problems, the participants were asked to think aloud. Usability problems occurred due to poorly structured information, insufficient quality of information, and a mismatch between experts’ and HCWs’ vocabulary. To overcome these shortcomings, three design principles were applied for communicating infection control guidelines: better navigation (the guidelines should be searchable in several ways); multimodality (the guidelines should not be presented as text only), and action-orientation (the guidelines should be presented as HCWs’ behaviors). A website was developed to meet these principles.In the second study, the same 28 HCWs completed tasks identical to those of the first study while thinking aloud, but this time using the website. The percentage of correctly completed tasks increased and the mean time for task completion decreased significantly. Also, respondents were more satisfied with the website than the paper-based guidelines. The number of problems due to poor information quality and a mismatch in vocabulary declined, although the number of structural problems increased. This can probably be explained by the fact that the navigation structure was user-generated (using Card Sort), in contrast to a standardized answer format based on common usability principles.Overall, we found that involving HCWs in the development process is important to create a sense of ownership and to foster the implementation of the guidelines, which might eventually result in compliance and reduce health care-associated infections. This paper outlines concrete steps for how to involve HCWs in the design process.     

Daily dietary lithium intake in Belgium using duplicate portion sampling

 For the first time, daily dietary lithium intake for adults in Belgium has been evaluated by duplicate portion sampling, the heating of the samples in a microwave oven and atomic absorption spectrometric determination of the element. The mean intake value for adults (8.6±4.6 μg/day) is very low compared to the scarce literature data. Since the lithium requirement of humans and animals is still unknown, no comparison could be made with RDA values.     

Use of activated silica sol as a flocculant in the treatment of acid mine drainage to promote sludge stability

The most common treatment for acidic drainage is lime neutralization. The process involves neutralization and precipitation of a metal hydroxide-gypsum sludge using a flocculant, generally Percol. In the short term, the sludge is stable, but in the long term, any tendency of pH to drop can re-dissolve metal hydroxides and contaminate the surrounding area and groundwater. The use of activated silica sol, an inorganic silicate polymer used in municipal water treatment, as a replacement to Percol is investigated to improve long term stability of sludge. Silica sol is an effective flocculant, has neutralization potential, and forms metal–silica bonds more resistant to pH variation than metal hydroxides. Various mine effluents and simulated solutions were treated with lime and silica sol or Percol to pH 9–10. Results show that settling characteristics with low dosages of silica sol and Percol are similar. Leachability tests showed that the stability of the sludge improved when silica sol was used for one cycle, and after 4 cycles results were similar to Percol. Activated silica sol, therefore, has the potential to increase sludge stability in a single stage lime treatment process.     

On a branch-and-bound approach for a Huff-like Stackelberg location problem

Modelling the location decision of two competing firms that intend to build a new facility in a planar market can be done by a Huff-like Stackelberg location problem. In a Huff-like model, the market share captured by a firm is given by a gravity model determined by distance calculations to facilities. In a Stackelberg model, the leader is the firm that locates first and takes into account the actions of the competing chain (follower) locating a new facility after the leader. The follower problem is known to be a hard global optimisation problem. The leader problem is even harder, since the leader has to decide on location given the optimal action of the follower. So far, in literature only heuristic approaches have been tested to solve the leader problem. Our research question is to solve the leader problem rigorously in the sense of having a guarantee on the reached accuracy. To answer this question, we develop a branch-and-bound approach. Essentially, the bounding is based on the zero sum concept: what is gain for one chain is loss for the other. We also discuss several ways of creating bounds for the underlying (follower) sub-problems, and show their performance for numerical cases. This work has been supported by the Ministry of Education and Science of Spain through grant SEJ2005/06273/ECON. M. Elena Sáz was supported by a junior research grant of Mansholt Graduate School (Wageningen Universiteit).     

Line-Interactive UPS Using a Fuel Cell as the Primary Source

This paper proposes a line-interactive fuel-cell-powered uninterruptible-power-supply system. A three-port bidirectional converter connects a fuel cell and a supercapacitor to a grid-interfacing inverter. The system can operate in both stand-alone and grid-connected modes. Moreover, an active filtering function is integrated into the system. It is shown that a supercapacitor can serve as both an active and a reactive energy storage and can buffer the periodical low-frequency ripple in the requested power. For connecting the system to the utility grid, a high-performance single-phase phase-locked loop that incorporates an orthogonal filter is presented. Resonant controllers for both the voltage and current regulations eliminate steady-state error and implement selective harmonic compensation. Simulation and experimental results are provided to show the feasibility of the proposed system and the effectiveness of the control methods.      

Depolarization and attenuation effects of radomes at 20 GHz

The problem of describing the attenuation and depolarization effects of a wet radome on a transmitted signal is considered by experiments carried out with two commonly used radome materials, ESSCOLAM-6 and ESSCOLAM-8. The results suggest that a two-component model of depolarization is required to account for the observed results. Predictions for the behavior of a complete radome are obtained, but full-scale testing with an operating radome to compare predicted and actual results remains to be done. An important conclusion is that while highly water-repellent radome materials are desirable from the point of view of attenuation experienced, they are not so desirable when considered in terms of the degree of depolarization introduced between orthogonally polarized signal components in frequency reuse systems     

Nanogram nitrite and nitrate determination in environmental and biological materials by vanadium (III) reduction with chemiluminescence detection

Nitrite in environmental water samples is reduced at room temperature to nitric oxide in acidic medium containing vanadium (III). Nitrate is also rapidly reduced after heating to 80-90 degrees C. Nitric oxide is removed from the reaction solution by scrubbing with helium carrier gas and is detected by means of a chemiluminescence NOx analyzer. Nanogram detection limits are obtained. The method has the advantage of not requiring highly acidic solutions for nitrate reduction and has been applied to the analysis of a variety of environmental waters, sediment, plant materials, and human urine and blood serum.     

Optimization of the cold rolling processing for continuous manufacturing of nanostructured Ti–Ni shape memory alloys

A Ø 1.0 mm Ti–50.26 at.% Ni wire is cold rolled by varying its thickness reduction (true thickness reduction from e = 0.25 to 2.0), the back and forward pulling tensions applied to the strip (from 0.1 to 0.5 of the material yield stress, σ_y) under dry and lubricated conditions, and then annealed to obtain a nanoscale grain structure or polygonized dislocation substructure, or their mixture. For the as-cold worked material, calorimetry, microhardness and optical microscopy are used to evaluate the quantity of the amorphized and ultrafine-grained phases, their mechanical properties, and the surface quality of the material. For the annealed material, tensile testing and recovery stress measurement are used to evaluate the mechanical and shape memory properties. It is found that for the same level of cold work, increasing the pulling tension leads to a decrease in the roll force and to a closer correspondence between the rolled product thickness and the set-up thickness. The higher the cold work reduction, the higher the quantity of the amorphized and ultrafine-grained phases and the higher the recovery stresses obtained after post-deformation annealing. On the other hand, the higher the thickness reduction, the larger the number of microcracks appearing on the samples’ edges. The average and the maximum lengths of the microcracks increase as the pulling stress applied to the strip increases. Lubrication decreases the average length of the microcracks, but does not affect their maximum length. From a functional properties perspective, lubricated cold rolling with a thickness reduction of e = 1.5 using back and forward pulling tensions of 0.1σ_y constitute optimal processing conditions, which allow a better trade-off between higher values of recovery stresses and the structural integrity of the sample.