Boundary factors and contextual contingencies: configuring electronic templates for healthcare professionals

In this paper, we propose an approach to balance the legitimate and yet conflicting perspectives between standardization and reconfiguration embedded within hospital information systems (HIS) design activities. We report on an action research study of the customization process of an electronic triage and tracking system that was reconfigured to be used in eight Canadian emergency departments. We argue that during HIS design activities, it is essential for both practitioners and system designers to articulate and identify which aspects can be standardized without constraining important local flexibility and which aspects require local reconfiguration to function in a particular work context. To identify these differences, we suggest an analytical distinction between boundary factors and contextual contingencies, which can be used in a design and reconfiguration process. We argue that the process of designing shared electronic templates should be perceived as a common design process, where multiple stakeholders articulate, identify, and negotiate boundary factors and contextual contingencies. Boundary factors are then represented within the shared electronic system, whereas contextual contingencies form the basis for constructing localized versions of the shared application. All local versions include both boundary factors and the reconfigured contextual contingencies.     

Bayes networks for estimating the number of solutions of constraint networks

The problem of counting the number of solutions to a constraint network (CN) (also called constraint satisfaction problems, CSPs) is rephrased in terms of probability updating in Bayes networks. Approximating the probabilities in Bayes networks is a problem which has been studied for a while, and may well provide a good approximation to counting the number of solutions. We use a simple approximation based on independence, and show that it is correct for tree‐structured CNs. For other CNs, it is less optimistic than a spanning‐tree approximation suggested in prior work. Experiments show that the Bayes nets estimation is more accurate on the average, compared to competing methods (the spanning‐tree, as well as a scheme based on a product of all compatible pairs of values). We present empirical evidence that our approximation may also be a useful (value ordering) search heuristic for finding a single solution to a constraint satisfaction problem. This revised version was published online in June 2006 with corrections to the Cover Date.     

Forensic analysis of nonlinear collusion attacks for multimedia fingerprinting.

Digital fingerprinting is a technology for tracing the distribution of multimedia content and protecting them from unauthorized redistribution. Unique identification information is embedded into each distributed copy of multimedia signal and serves as a digital fingerprint. Collusion attack is a cost-effective attack against digital fingerprinting, where colluders combine several copies with the same content but different fingerprints to remove or attenuate the original fingerprints. In this paper, we investigate the average collusion attack and several basic nonlinear collusions on independent Gaussian fingerprints, and study their effectiveness and the impact on the perceptual quality. With unbounded Gaussian fingerprints, perceivable distortion may exist in the fingerprinted copies as well as the copies after the collusion attacks. In order to remove this perceptual distortion, we introduce bounded Gaussian-like fingerprints and study their performance under collusion attacks. We also study several commonly used detection statistics and analyze their performance under collusion attacks. We further propose a preprocessing technique of the extracted fingerprints specifically for collusion scenarios to improve the detection performance.     

Stable, tunable calibration source for large-beam optical systems

An optical calibration source for free-space systems with large beams is presented. It produces a 2 W, 370 mm beam tunable from 1545-1570 nm with a wavefront error of 相似文献   

Local electrochemical impedance spectroscopy: Considerations about the cell geometry

Local electrochemical impedance spectroscopy provides a powerful tool for the investigation of surface heterogeneities on electrode surfaces. However, measurements are greatly influenced by geometry-induced frequency dispersion. In order to account for this frequency dispersion, both simulations and experiments were performed to explore the influence of a recessed electrode on the local and global impedance response. The calculations presented here demonstrated that the depth of the recessed electrode required to achieve a uniform primary current distribution was twice the electrode radius. The calculations provide guidelines for design of LEIS measurements, and were in good agreement with results obtained for a stainless steel disk electrode in a Na₂SO₄ electrolyte.     

The impact of pre‐ and/or probiotics on human colonic metabolism: Does it affect human health?

Since many years, the role of the colonic microbiota in maintaining the host's overall health and well-being has been recognized. Dietary modulation of the microbiota composition and activity has been achieved by the use of pre-, pro- and synbiotics. In this review, we will summarize the available evidence on the modification of bacterial metabolism by dietary intervention with pre-, pro- and synbiotics. Enhanced production of SCFA as a marker of increased saccharolytic fermentation is well documented in animal and in vitro studies. Decreased production of potentially toxic protein fermentation metabolites, such as sulfides, phenolic and indolic compounds, has been less frequently demonstrated. Besides, pre-, pro- and synbiotics also affect other metabolic pathways such as the deconjugation of secondary bile acids, bacterial enzyme activities and mineral absorption. Data from human studies are less conclusive. The emergence of new analytical techniques such as metabolite profiling has revealed new pathways affected by dietary intervention. However, an important challenge for current and future research is to relate changes in bacterial metabolism to concrete health benefits. Potential targets and expected benefits have been identified: reduced risk for the metabolic syndrome and prevention of colorectal cancer.