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PubMed2001

Radiographic wear measurements in a cementless metal-backed modular cobalt-chromium acetabular component.

Linear polyethylene wear was measured radiographically and correlated with direct measurements of wear from 21 of 24 liners retrieved at revision. An optical comparator was used to assess linear wear using the shadowgraph technique. Postoperative and prerevision radiographs were reviewed to measure the amount of linear wear radiographically. Seven radiographic methods described in the literature were used: 5 were manual techniques, and 2 techniques used a computer-assisted digitizer. Linear regression analysis showed that there was a statistically significant correlation between the radiographic measurements compared with the direct measurement for 4 of the 5 manual techniques but only 1 of the 2 computerized techniques. Based on these results, radiographic wear measurements of cementless, modular components should be considered qualitative rather than quantitative. There is a significant difference in the measurements obtained among various published techniques. The addition of computer digitization to enhance manual methodology does not improve accuracy.

Acetabulum↗
PubMed2004

A quantum chemical approach to the free energy calculations in condensed systems: the QM/MM method combined with the theory of energy representation.

A methodology has been proposed to compute the solvation free energy of a molecule described quantum chemically by means of quantum mechanical/molecular mechanical method combined with the theory of energy representation (QM/MM-ER). The present approximate approach is quite simple to implement and requires much less computational cost as compared with the free energy perturbation or thermodynamic integration. Furthermore, the electron distribution can be treated faithfully as a quantum chemical object, and it is no longer needed to employ the artificial interaction site model, a reduced form of the realistic electron distribution, which is commonly used in the conventional solution theory. The point of the present approach is to employ the QM solute with electron density fixed at its average distribution in order to make the solute-solvent interaction pairwise. Then, the solvation free energy can be computed within the standard framework of the energy representation. The remaining minor contribution originating from the many-body effect inherent in the quantum mechanical description can be evaluated separately within a similar framework if necessary. As a test calculation, the method has been applied to a QM water solute solvated by MM water solvent in ambient and supercritical states. The results of the QM/MM-ER simulations have been in excellent agreement with the experimental values.

Journal Article↗
PubMed2000

A comparison between human and machine labelling of image regions.

In previous work (Campbell et al, 1997 Pattern Recognition 30 555-563) a vision system was developed which is capable of classifying objects in outdoor scenes. The approach involves segmenting the image into regions, obtaining a feature-based description of each region, and then passing this description on to an artificial neural network (ANN) which has been trained to label the region with one of eleven possible object types. The question addressed here is: how important is each of these features to overall performance, both in human and machine vision? A set of experiments was conducted in which human subjects were trained in the same labelling task as the ANN. The stimuli, each depicting a single image region, were generated from a large database of urban and rural images. The subjects were then tested on both intact and degraded stimuli. The results suggest that certain features are particularly influential in mediating overall labelling performance. An equivalent experiment was carried out with the ANN. A method is presented which allows individual features to be corrupted in such a way as to simulate the loss of certain forms of visual information. The results, which are broadly similar to those found in the previous experiment, imply that the ANN can provide a useful model of human image region labelling. It is anticipated that the methodology, which draws on both computational and psychophysical techniques, will be of use to other areas of investigation.

Adult↗
PubMed2003

Numerical determination of personal aerosol sampler aspiration efficiency.

In this work the determination of the aspiration efficiency of personal aerosol samplers, commonly used in occupational exposure assessment, is investigated by means of CFD techniques. Specifically, it will be described a code to calculate the particle trajectories in a given flow field. At the present state the code considers only the effects of the mean flow field on the particle motion, whereas the turbulent diffusion effects are neglected. Comparisons with experimental measurements are also given in the framework of a research contract, supported by the European Community, with several experimental contributions from the participants. The main objective of the European research is to develop a new approach to experimentation with airborne particle flows, working on a reduced scale. This methodology has the advantage of allowing real-time aerosol determination and use of small wind tunnels, with a better experimental control. In this article we describe how the methodology has been verified using computational fluid dynamics. Experimental and numerical aspiration efficiencies have been compared and the influence of gravity and turbulence intensity in full and reduced scale has been investigated. The numerical techniques described here are in agreement with previous similar research and allow at least qualitative predictions of aspiration efficiency for real samplers, taking care of orientation from the incoming air flow. The major discrepancies among predicted and experimental results may be a consequence of bounce effects, which are very difficult to eliminate also by greasing the sampler surface.

Aerosols↗
PubMed1994

Structural basis of antimutagenicity of chemicals towards 4-nitroquinoline 1-oxide in Salmonella typhimurium.

Eighty-eight organic compounds representing a variety of chemical classes, a proportion of which possess antimutagenic and/or anticarcinogenic properties, were compared for their ability to inhibit the direct-acting mutagenicity of 4-nitroquinoline 1-oxide (4NQO) in strain TA100 of Salmonella typhimurium. Twelve compounds were found to decrease 4NQO-induced mutagenicity by at least 50%, with an antimutagenic potency varying over a 1225-fold range, corresponding to a 4-4900 molar excess of inhibitor over that of 4NQO. The resulting antimutagenicity data base was subjected to structural analysis by the computer automated structure evaluation (CASE) methodology, which identified one structural determinant (biophore) and four biophobes. The biophore contained the sulfhydryl group, present in three thiols and five aminothiols, all of which inhibited 4NQO mutagenicity. Conversely, the corresponding disulphides or thioethers as well as dithiocarbamates, isothiocyanates and other sulfur-containing compounds were devoid of antimutagenicity towards 4NQO. A distinctive dichotomy in the ability to inhibit 4NQO mutagenicity was observed with pairs of structurally and metabolically related compounds, such as the polyamines spermidine (antimutagenic) versus spermine and the tetrapyrroles bilirubin (antimutagenic) versus biliverdine. Curcumin and myricetin were the only inhibitors of 4NQO-induced mutagenicity out of a group of 12 phenols and three bioflavonoids, respectively. One biophobe was an oxidized sulfhydryl moiety, while the other three were derived from benzene or its derivatives. Some of these phenyl compounds are known antioxidants. Thus, nucleophilicity rather than antioxidant properties appears to play a role in antimutagenicity to 4NQO.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Nitroquinoline-1-oxide↗
PubMed1994

Prediction of rodent carcinogenicity for 44 chemicals: results.

Methods by which rodent carcinogenicity can be predicted have been prospectively validated for 40 chemicals evaluated for carcinogenicity by the US National Toxicology Program. It is concluded that a chemical of unknown carcinogenicity can be predicted to be in one of three possible categories--probably carcinogenic, probably non-carcinogenic or of uncertain activity. The last category is unlikely to contain genotoxic trans-species and/or multiple-site carcinogens. The component parameters of such predictions are one or more of several aspects of chemical structure, genotoxicity and rodent toxicity. Each of these parameters requires refinement but all are developed to the point that they can be integrated to make assessment of possible carcinogenicity. Carcinogenicity tends to be overpredicted by this integrated technique, each part of which has already been simulated by computer modelling. Improvements in predictive methodology will flow from three assumptions: (i) that emphasis must be placed equally on the properties of the test chemical and the responses it elicits in tissues for which carcinogenicity is to be predicted, (ii) that the integration of different predictive technique is preferable to the exclusive use of a single technique, and (iii) that the general predictivity of any technique or combination of techniques appears to be limited to < or = 80%, imposed by inadequate knowledge, and uncertainties in the experimental evaluation and classification of carcinogenic responses for diverse chemicals. This last statement does not preclude the attainment of higher accuracy within a congeneric series of chemicals. Foreknowledge of the likely outcome of a rodent carcinogenicity bioassay is now possible and will contribute to the focusing of animal testing resources.

Animals↗
PubMed2000

Intensive care unit telemedicine: alternate paradigm for providing continuous intensivist care.

OBJECTIVE: Intensive care units (ICUs) account for an increasing percentage of hospital admissions and resource consumption. Adverse events are common in ICU patients and contribute to high mortality rates and costs. Although evidence demonstrates reduced complications and mortality when intensivists manage ICU patients, a dramatic national shortage of these specialists precludes most hospitals from implementing an around-the-clock, on-site intensivist care model. Alternate strategies are needed to bring expertise and proactive, continuous care to the critically ill. We evaluated the feasibility of using telemedicine as a means of achieving 24-hr intensivist oversight and improved clinical outcomes. DESIGN: Observational time series triple cohort study. SETTING: A ten-bed surgical ICU in an academic-affiliated community hospital. PATIENTS: All patients whose entire ICU stay occurred within the study periods. INTERVENTIONS: A 16-wk program of continuous intensivist oversight was instituted in a surgical ICU, where before the intervention, intensivist consultation was available but there were no on-site intensivists. Intensivists provided management during the intervention using remote monitoring methodologies (video conferencing and computer-based data transmission) to obtain clinical information and to communicate with on-site personnel. To assess the benefit of the remote management program, clinical and economic performance during the intervention were compared with two 16-wk periods within the year before the intervention. MEASUREMENTS AND MAIN RESULTS: ICU and hospital mortality (observed and Acute Physiology and Chronic Health Evaluation III, severity-adjusted), ICU complications, ICU and hospital length-of-stay, and ICU and hospital costs were measured during the 3 study periods. Severity-adjusted ICU mortality decreased during the intervention period by 68% and 46%, compared with baseline periods one and two, respectively. Severity-adjusted hospital mortality decreased by 33% and 30%, and the incidence of ICU complications was decreased by 44% and 50%. ICU length of stay decreased by 34% and 30%, and ICU costs decreased by 33% and 36%, respectively. The cost savings were associated with a lower incidence of complications. CONCLUSIONS: Technology-enabled remote care can be used to provide continuous ICU patient management and to achieve improved clinical and economic outcomes. This intervention's success suggests that remote care programs may provide a means of improving quality of care and reducing costs when on-site intensivist coverage is not available.

APACHE↗
PubMed1999

The effects of local spatial structure on epidemiological invasions.

Predicting the likely success of invasions is vitally important in ecology and especially epidemiology. Whether an organism can successfully invade and persist in the short-term is highly dependent on the spatial correlations that develop in the early stages of invasion. By modelling the correlations between individuals, we are able to understand the role of spatial heterogeneity in invasion dynamics without the need for large-scale computer simulations. Here, a natural methodology is developed for modelling the behaviour of individuals in a fixed network. This formulation is applied to the spread of a disease through a structured network to determine invasion thresholds and some statistical properties of a single epidemic.

Communicable Disease Control↗
PubMed2004

Risky drinking and alcohol use patterns in a national sample of women of childbearing age.

AIMS: We examined risky drinking and alcohol use patterns associated with prenatal effects of alcohol exposure in women of childbearing age, using various definitions of low-risk drinking. DESIGN: Computer-assisted telephone interview (CATI) methodology was used to gather information in a cross-sectional survey on alcohol use and problems, pregnancy and likelihood of future pregnancy. SETTING: Participants were respondents in the 2000 National Alcohol Survey (NAS, N10, response rate 58%) which includes men and women from all 50 states of the United States and the District of Columbia. PARTICIPANTS: A total of 1504 women aged 18-39 years were included; 72 were pregnant, 511 were currently not pregnant but reported being likely to be pregnant in the next 5 years, and 921 women were neither pregnant nor likely to be in the next 5 years. MEASUREMENTS: Various alcohol use patterns in the past 12 months including average volume, amount per session, drinking with food and time spent drinking were assessed. FINDINGS: Seven per cent of childbearing age women exceeded guidelines used to classify women as risky drinkers in the past month. Thirty per cent were classified as risky drinkers when these guidelines were extended to past-year drinking. Examination of specific alcohol use patterns revealed that while under 10% of risky drinkers reported past-month heavy episodic drinking, 30% or more reported heavy episodic drinking and exceeding daily limits for alcohol consumption in the past year. CONCLUSIONS: Public health professionals should note that past-year drinking in a significant proportion of women of childbearing age exceeds guidelines for alcohol use. When targeting such prevention efforts, they should thus include assessment of past-year alcohol use patterns.

Adolescent↗
PubMed2003

Domestic violence in South Australia: a population survey of males and females.

OBJECTIVE: To determine the self-reported prevalence of domestic violence in South Australian adults and to examine the associated risk factors, demographic factors and related health issues using computer-aided telephone interviewing (CATI) methodology. SAMPLE: A representative random sample of South Australian adults aged 18 years and over selected from the Electronic White Pages. Overall, 6,004 interviews were completed (73.1% response rate). RESULTS: In total, 17.8% of adults in South Australia reported some form of domestic violence by a current or an ex-partner. Demographic factors such as low household income, unemployment or part-time employment and health variables such as poor to fair self-reported health status and alcohol abuse problems were found to have a significant relationship with domestic violence. CONCLUSIONS: Approximately one in five South Australian adults report physical and emotional abuse from current or ex-partners, of whom the majority are women who are separated, divorced or never married and on lower incomes. Telephone interviewing is a cost-effective method of identifying prevalence estimates of domestic violence when compared with data collection by way of police reports or hospital emergency statistics. IMPLICATIONS: Domestic violence is a serious public health concern often 'hidden' by the lack of appropriate data. This study has shown that domestic violence is frequent and has important social, economic and health consequences.

Adult↗
PubMed2006

Neuro-fuzzy decision trees.

Fuzzy decision trees are powerful, top-down, hierarchical search methodology to extract human interpretable classification rules. However, they are often criticized to result in poor learning accuracy. In this paper, we propose Neuro-Fuzzy Decision Trees (N-FDTs); a fuzzy decision tree structure with neural like parameter adaptation strategy. In the forward cycle, we construct fuzzy decision trees using any of the standard induction algorithms like fuzzy ID3. In the feedback cycle, parameters of fuzzy decision trees have been adapted using stochastic gradient descent algorithm by traversing back from leaf to root nodes. With this strategy, during the parameter adaptation stage, we keep the hierarchical structure of fuzzy decision trees intact. The proposed approach of applying backpropagation algorithm directly on the structure of fuzzy decision trees improves its learning accuracy without compromising the comprehensibility (interpretability). The proposed methodology has been validated using computational experiments on real-world datasets.

Decision Making, Computer-Assisted↗
PubMedDate not supplied

A brief primer on automated signal detection.

BACKGROUND: Statistical techniques have traditionally been underused in spontaneous reporting systems used for postmarketing surveillance of adverse drug events. Regulatory agencies, pharmaceutical companies, and drug monitoring centers have recently devoted considerable efforts to develop and implement computer-assisted automated signal detection methodologies that employ statistical theory to enhance screening efforts of expert clinical reviewers. OBJECTIVE: To provide a concise state-of-the-art review of the most commonly used automated signal detection procedures, including the underlying statistical concepts, performance characteristics, and outstanding limitations, and issues to be resolved. DATA SOURCES: Primary articles were identified by MEDLINE search (1965-December 2002) and through secondary sources. STUDY SELECTION AND DATA EXTRACTION: All of the articles identified from the data sources were evaluated and all information deemed relevant was included in this review. DATA SYNTHESIS: Commonly used methods of automated signal detection are self-contained and involve screening large databases of spontaneous adverse event reports in search of interestingly large disproportionalities or dependencies between significant variables, usually single drug-event pairs, based on an underlying model of statistical independence. The models vary according to the underlying model of statistical independence and whether additional mathematical modeling using Bayesian analysis is applied to the crude measures of disproportionality. There are many potential advantages and disadvantages of these methods, as well as significant unresolved issues related to the application of these techniques, including lack of comprehensive head-to-head comparisons in a single large transnational database, lack of prospective evaluations, and the lack of gold standard of signal detection. CONCLUSIONS: Current methods of automated signal detection are nonclinical and only highlight deviations from independence without explaining whether these deviations are due to a causal linkage or numerous potential confounders. They therefore cannot replace expert clinical reviewers, but can help them to focus attention when confronted with the difficult task of screening huge numbers of drug-event combinations for potential signals. Important questions remain to be answered about the performance characteristics of these methods. Pharmacovigilance professionals should take the time to learn the underlying mathematical concepts in order to critically evaluate accumulating experience pertaining to the relative performance characteristics of these methods that are incompletely defined.

Automation↗
PubMed2006

The use of deep and surface learning strategies among students learning English as a foreign language in an Internet environment.

BACKGROUND: The learning context is learning English in an Internet environment. The examination of this learning process was based on the Biggs and Moore's teaching-learning model (Biggs & Moore, 1993). AIM: The research aims to explore the use of the deep and surface strategies in an Internet environment among EFL students who come from different socio-economic backgrounds. The results of the research may add an additional level to the understanding of students' functioning in the Internet environment. SAMPLE: One hundred fourty-eight Israeli junior and high school students participated in this research. METHODS: The methodology was based on special computer software: Screen Cam, which recorded the students' learning process. In addition, expert judges completed a questionnaire which examined and categorized the students' learning strategies. RESULTS: The research findings show a clear preference of participants from all socio-economic backgrounds towards the surface learning strategy. The findings also showed that students from the medium to high socio-economic background used both learning strategies more frequently than low socio-economic students. CONCLUSIONS: The results reflect the habits that students acquire during their adjustment process throughout their education careers. A brief encounter with the Internet learning environment apparently cannot change norms or habits, which were acquired in the non-Internet learning environment.

Female↗
PubMed2004

Computerized protocol for anatomical and functional studies of joints.

This chapter describes a new methodology for the acquisition and computer elaboration of joint anatomy and motion data and the study of their correlation. The method uses a commercial industrial electrogoniometer, custom tools, and software designed and developed by the authors for interactive display of the anatomical structures during joint motion, numerical interpolations of the articular geometries, and kinematic analysis of motion. The original data acquisition protocol and computer elaboration software are described in detail, and a final subheading describes briefly previous studies and future developments.

Biomechanical Phenomena↗
PubMed2004

Prediction of daily and lactation yields of milk, fat, and protein using an autoregressive repeatability test day model.

We evaluated the accuracy of an autoregressive multiple-lactation test day (ATD) model to predict missing test day yields of milk, fat, and protein to obtain cumulative 305-d records for cows with incomplete or in-progress lactations. The data consisted of more than one million observations of daily yields on test days in the first 3 lactations of over 75,000 Portuguese Holstein cows. Differences between actual (estimates from complete lactations using the test interval method) and ATD-predicted 305-d yields were negligible and smaller than those predicted by the test interval method. The ATD procedure tended to slightly underestimate cumulative lactation yields, whereas the test interval method substantially overestimated them. Smaller differences obtained by the ATD procedure resulted in less biased estimates of lactation yield, which also implies greater accuracy. As expected, the correlations between actual and predicted lactation yields increased with the number of test days from 0.831 to 0.997. Average correlations (by parity) between actual and ATD-predicted yields ranged from 0.977 to 0.984. Correlations between actual test day yields and corresponding predicted yields exceeded 0.5 for up to 7 time-intervals from the last test day yield used to predict cumulative yield of projected lactations. These correlations indicate the good predictive ability of the ATD method. From a producer's viewpoint, these advantages underwrite management because most on-farm selection decisions are based on the producing abilities of cows. Implementation of ATD methodology does not require special computing capability and is easily transferable to the farm level.

Animals↗
PubMed1992

Revitalizing executive information systems.

As the saying goes, "garbage in, garbage out"--and this is as true for executive information systems as for any other computer system. Crockett presents a methodology he has used with clients to help them develop more useful systems that produce higher quality information. The key is to develop performance measures based on critical success factors and stakeholder expectations and then to link them cross functionally to show how progress is being made on strategic goals. Feedback from the executive information system then informs strategy formulation, business plan development, and operational activities.

Data Collection↗
PubMed2002

[Modeling transfer and partitioning of potentially toxic pollutants in soil-crop system for human food security].

Human exposure to potential toxic pollutants and the associated health risk is a focus of current environmental and medical studies. However, the transfer and partitioning of the pollutants in the soil-crop systems turns to be a key problem for evaluating the food intake of the pollutants. This paper deals with the methodology and the approach of computer modeling of the soil-crop partitioning of the pollutants under agricultural systems for human food security and the elaboration of guidelines for soil protection. Two major models, crop ecological model and soil environmental chemical model, are discussed respectively. These models may be valuable for the research of agricultural environment protection and the development of guidelines for soil protection in China.

Consumer Product Safety↗