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At least 199 records · Page 11Linked to original sources

PubMed1996

Methodological aspects of using decision trees to characterise leiomyomatous tumors.

The aim of the present work is to present the potential uses of a classification technique labeled the "decision tree" for tumor characterisation when faced with a large number of features. The decision tree technique enables multifeature logical classification rules to be produced by determining discriminatory values for each feature selected. In this report, we propose a methodology that used decision trees to compare and evaluate the information contributed by different types of features for tumor characterisation. This methodology is able to produce a set of hypotheses related to a diagnosis and or prognosis problem. For example, hypotheses can be producted (on the basis of a set of descriptive features) to explain why tumor cases belong to a given histopathological group. To illustrate our purpose, this methodology was applied to the difficult problem of leiomyomatous tumour diagnosis. The aim was to illustrate what kind of diagnostic information can be extracted from a sample data set including 23 smooth muscle tumors (14 benign leiomyomas and 9 malignant leiomyosarcomas) described by a large set of computer-assisted, microscope-generated features. Three groups of features were used relating to: (1) ploidy level determination (10 features), (2) quantitative chromatin pattern description (15 features), and (3) immunohistochemically related antigen specificities (6 features). All these features were quantified by digital cell image analysis. The results suggest that an objective distinction between leiomyomas and leiomyosarcomas can be established by means of simple logical rules depending on only a few features among which the immunohistochemically revealed antigen expression of desmin plays a preponderant part. One of the combinations of features proposed by the methodology is interesting for pathologists, because it includes two features describing the appearance of a nucleus in terms of chromatin distribution homogeneity and density, two features widely used by pathologists in tumor-grading systems.

Adolescent↗

PubMed1976

Darwinism and positivism as methodological influences on the development of psychology.

The methodological significance of evolutionary theory for psychology may be distinguished from its substantive or theoretical significance. The methodological significance was that evolutionay theory broadened the current conceptors of scientific method and rendered them relatively independent of physics. It thereby made the application of the "scientific method" to psychology much more feasible than it had been previously, and thus established the possibility of a wide-ranging scientific psychology for the first time. The methodological eclecticism that made scientific psychology possible did not, however, remain a feature of psychology for very long. Psychology's methodology rapidly became restricted and codified through the influence of, and in imitation of, the rigorously positivistic orientation of physics around the turn of the twentieth century.

Biological Evolution↗

PubMed2006

Prevalence of tic disorder in two schools in the Basque country: Results and methodological caveats.

Different studies have shown that the prevalence of tic disorder is highly variable, depending on the methodology employed. The aim of this study was to determine the prevalence of tic disorder among children of two schools. The study was conducted in three successive steps: information to parents and teachers by way of speeches and projection of videotapes; anonymous fulfilling of an ad hoc questionnaire by teachers and parents and identification of children as "possible tic disorder" according to the questionnaire; and confirmation of the presence of tics by direct observation of children at school (20 minutes in each classroom). Eight hundred sixty-seven children were included. Age ranged from 4 to 16 years. Ninety percent of parents and 99% of teachers fulfilled the questionnaire. Seventy-one children had tics according to parents' and 50 according to teachers' opinion (both coincided in 23 cases). Fifty-seven cases were identified after direct observation in the classroom (prevalence of 6.5%). The vast majority of tics were mild in severity and duration. Prevalence obtained in this study was comparable with data reported in studies using a similar methodology, which is higher than results shown in early studies addressed with less rigid methodology. Most of identified cases were quite mild, not leading to major functional disability. In spite of the methodology employed, it is possible that some cases were lost.

Adolescent↗

PubMed2005

Methodological issues related to exhaled nitric oxide measurement in children aged four to six years.

This study was designed to test five methodological issues related to measurement of fractional exhaled nitric oxide (FE(NO)) in children aged 4-6 years using commercially available apparatus. Participants attended two randomly selected schools. A respiratory questionnaire was completed. Measurements of FE(NO) were made on successive days, using a NIOX analyzer employing standard or modified methodologies. Ninety-one children participated in the study (mean age, 5.3 years; 46 boys). Using a standard methodology (n = 61), FE(NO) was successfully measured in 28 (46%) children, 1/12 aged 4 years, 12/25 aged 5 years, and 15/24 aged 6 years (trend test P = 0.01). On the first assessment, FE(NO) could be determined in more boys than girls (64% vs. 30%, respectively, P = 0.008), but this gender difference was not apparent on the second assessment. Exhaled NO was reproducible over a 24-hr period; the mean difference between repeated measurements of natural log (ln) FE(NO) was 0.016 parts per billion (ppb) (95% confidence limits, -0.479, 0.511), n = 20. Data from 35 assessments showed that values of FE(NO) did not alter over nine individual, successive measurements. Use of a modified methodology in 30 children increased success in obtaining FE(NO), but these values were unreliable. In conclusion, measurements of FE(NO) can be obtained in the majority of 5- and 6-year-old but not 4-year-old children. Exhaled NO measurements were reproducible over a 24-hr interval, and did not change over up to nine expiratory maneuvers in these young children.

Age Factors↗

PubMed2001

Estimating the efficacy of interventions to prevent mother-to-child transmission of HIV in breast-feeding populations: development of a consensus methodology.

Postnatal transmission of HIV through breast milk complicates both the design of effective interventions to prevent mother-to-child transmission of HIV (PMTCT) and their evaluation. Estimated long-term efficacy in five African trials (four with peri-partum antiretrovirals and one with artificial feeding) varied from 25 to 50 per cent. This variation may be due, at least in part, to differences in analytical methodology. To facilitate direct comparison between trials, a methodological consensus approach to the analysis and presentation of the results of PMTCT trials was developed. The initial methodology used and results presented from African trials with available long-term efficacy data were reviewed during a workshop in Bordeaux, France, in September 2000. A consensus approach for evaluating efficacy applicable across PMTCT studies was developed. There are four typical situations defined by duration of follow-up (short versus long), and the available demographic (vital status) and biological data (single versus repeat HIV testing). Efficacy can be assessed from the risk of infection directly or from HIV-free survival by combining infection and death as a single endpoint. Studies should report results in a standardized format including infection, weaning, mortality and loss to follow-up. New statistical methods that account for the unknown date when a child would first test positive for HIV, for weaning as a competing risk for HIV infection, and for increased risk of death among HIV-infected children should be used in analysing data from PMTCT studies with repeat HIV testing. All estimates should be reported with confidence intervals. This standardized methodology that allows direct comparison between studies is now being applied to four randomized clinical trials.

Antiviral Agents↗

PubMed1990

The impact of methodological factors on child psychotherapy outcome research: a meta-analysis for researchers.

Two recent meta-analyses have generated evidence for child and adolescent psychotherapy effects. However, critics note that such meta-analyses often include studies with methodological shortcomings which might invalidate their results. In the present study, we explored whether the results of the most extensive child/adolescent meta-analysis might have been influenced by such methodological variables, focusing on internal validity and external validity factors. Together, these factors accounted for two-thirds as much variance as the substantive factors (e.g., type of therapy, age) in the original meta-analysis. This suggests that relative to these therapy and child-characteristic variables, methodological factors have a substantial, though smaller, impact on meta-analysis results. In general, increased experimental rigor was related to larger effect sizes; this argues against the hypothesis that methodologically weak studies have led to an overestimate of therapy effects. No significant interactive relations were found between validity factors and predictors of outcome; this suggests that the relations noted in previous meta-analyses between outcome and various variables were not distorted by the validity factors tested here.

Adaptation, Psychological↗

PubMed1993

Utilization patterns of total parenteral nutrition in a university hospital. A methodological approach.

To study the utilization of total parenteral nutrition, using methodology recommended by the World Health Organization, classification of components in accordance with the anatomical therapeutic chemical classification and defined daily dose system is necessary. Anatomical therapeutic chemical indices are available but defined daily dose values have not been established yet. In this article, a methodology to study both the total utilization of total parenteral nutrition, the utilization of individual substances and the composition of total parenteral nutrition is presented. To validate the proposed methodology, the utilization of total parenteral nutrition in a teaching hospital is studied, based on pharmacy computer data. The total utilization of total parenteral nutrition in the hospital in 1990 is 1.4 defined daily doses/100 bed-days. The composition of total parenteral nutrition varied greatly between the clusters. In this study we showed that utilization of total parenteral nutrition can be measured with the proposed methodology, using a defined daily dose for total parenteral nutrition in concurrence with a defined daily dose for the individual components.

Diet↗

PubMed1993

Is there a valid association between skin tags and colonic polyps: insights from a quantitative and methodologic analysis of the literature.

OBJECTIVE: To assess the reported association between skin tags and colonic polyps and to evaluate the methodologic rigor of the studies. DESIGN AND DATA IDENTIFICATION: English-language literature search using MEDLINE, Index Medicus, and bibliographic reviews of texts and all pertinent articles to perform a quantitative and methodologic analysis of all studies from 1983 (the original publication) assessing the association under study. Eligible studies were independently assessed using explicit methodologic guidelines for validity and generalizability of observational research. Two appraisers independently performed tests for heterogeneity and used meta-analytic methods in an attempt to provide summary estimates of the overall strength of association. MEASUREMENTS AND MAIN RESULTS: Significant statistical heterogeneity across studies indicated sharp differences in the direction and magnitude of the odds ratios for the association between skin tags and colonic polyps (chi-square test of homogeneity = 37.42, 9 degrees of freedom; p < 0.005). This marked disparity prevented meaningful pooling of the individual data. The degree of statistical heterogeneity was not significantly reduced after an analysis of specific subgroups of studies. Limitations potentially responsible for the varying outcomes included lack of blinded ascertainment of clinical information, noncomparability of subjects, differing diagnostic evaluations of the colon, and uncontrolled confounding. In addition, all but one study were performed in a tertiary care setting, seriously limiting the results to the "average" subject seen in primary care settings. CONCLUSION: Methodologic limitations and inconsistencies in study outcomes preclude the aggregation of data necessary to compute a valid and meaningful summary estimate of association. Sufficient variability prevents any consensus regarding the association between skin tags and colonic polyps. In addition, the applicability of the results is limited primarily to subjects seen in tertiary care centers, limiting the overall clinical usefulness of skin tags as "biomarkers" of colonic polyps. Recommendations for further research are provided.

Adult↗

PubMed1998

Modification of the ferrozine technique to analyze iron contents in different foods: comparative study using an internal standard as reference methodology.

A methodology for the determination of iron in foods fortified with this element or in nutritional products is important and has to be sensitive and rapid. In developing countries, an inexpensive and reliable methodology is also required. For this purpose, the Gordon's Ferrozine technique was slightly modified and assayed with yogurt, dry powdered milk, and cereal mixtures, all of them fortified with iron, using an internal standard as the reference methodology. The obtained results demonstrate a close correlation between the standard curve interpolation method and the internal standard reference method (correlation coefficient r2 = 0.9950) in a wide range of concentrations. The slope (0.9998+/-0.0040) demonstrates that both procedures measure equal amounts of iron. The conclusion is that the proposed technique is a reliable, practical, and inexpensive methodology for iron determination in different foods fortified with iron.

Ferrozine↗

PubMed2004

An ultrasonic methodology for muscle cross section measurement to support space flight.

The number one priority for any manned space mission is the health and safety of its crew. The study of the short and long term physiological effects on humans is paramount to ensuring crew health and mission success. One of the challenges associated in studying the physiological effects of space flight on humans, such as loss of bone and muscle mass, has been that of readily attaining the data needed to characterize the changes. The small sampling size of astronauts, together with the fact that most physiological data collection tends to be rather tedious, continues to hinder elucidation of the underlying mechanisms responsible for the observed changes that occur in space. Better characterization of the muscle loss experienced by astronauts requires that new technologies be implemented. To this end, we have begun to validate a 360 degree ultrasonic scanning methodology for muscle measurements and have performed empirical sampling of a limb surrogate for comparison. Ultrasonic wave propagation was simulated using 144 stations of rotated arm and calf MRI images. These simulations were intended to provide a preliminary check of the scanning methodology and data analysis before its implementation with hardware. Pulse-echo waveforms were processed for each rotation station to characterize fat, muscle, bone, and limb boundary interfaces. The percentage error between MRI reference values and calculated muscle areas, as determined from reflection points for calf and arm cross sections, was -2.179% and +2.129%, respectively. These successful simulations suggest that ultrasound pulse scanning can be used to effectively determine limb cross-sectional areas. Cross-sectional images of a limb surrogate were then used to simulate signal measurements at several rotation angles, with ultrasonic pulse-echo sampling performed experimentally at the same stations on the actual limb surrogate to corroborate the results. The objective of the surrogate sampling was to compare the signal output of the simulation tool used as a methodology validation for actual tissue signals. The disturbance patterns of the simulated and sampled waveforms were consistent. Although only discussed as a small part of the work presented, the sampling portion also helped identify important considerations such as tissue compression and transducer positioning for future work involving tissue scanning with this methodology.

Animals↗

PubMed1999

Picture archiving and communication systems planning: a methodology.

This article presents the Picture Archiving and Communication Systems (PACS) planning methodology used by the Department of Defense's (DOD) Joint Imaging Technology Project Office (JITPO). This methodology evaluates four areas of PACS planning and implementation: strategic planning, clinical scenario planning, installation planning, and implementation planning. The first task is to develop a PACS team, from the local facility, that will execute the program. A written PACS plan is developed by the JITPO, with active input and final say from the site's PACS team. This plan includes the PACS goals and objectives, clinical requirements, facility requirements, and the status of the implementation. This methodology, when applied fully at a military clinical site, has resulted in the site obtaining best "value" in terms of cost and performance by requiring the DOD's contracted PACS vendors to propose a PACS package that meets or exceeds the site's unique requirements. The identification of the requirements and the matching of a known PACS configuration with them has reduced the number of unknowns within the vendors' proposals and created true competition in both initial cost and the cost to maintain PACS in the maintenance years. Although there are certain factors unique to planning a military PACS, such as preselected vendors, the planning methodology described in this article should provide a valuable strategy for any hospital planning a PACS.

Hospitals, Military↗

PubMed2001

Strategic environmental assessment of plans and programs: a methodology for estimating effects on biodiversity.

We developed a methodology for biodiversity evaluations within the process of Strategic Environmental Assessment and we applied it to the estimation of the effect of two Regional Plans of Development on all bird species inhabiting the Castilla y León region (northwestern Spain). The methodology is based on the evaluation of the effects of main development actions on the habitat requirements of species. From these evaluations, and from data on the current distribution and population size (number of individuals) of each species, we estimated the most likely pattern of distribution and population size after the full implementation of the plans for each species. The impacts of the plans were quantified as the differences between the pre- and postproject patterns after codifying them to compensate for differences in the quality of the information available among species. Overall, we conclude that the proposed methodology fulfills the requirements for its use within the SEA process as it allows for the assessment of cumulative impacts on every species, highlighting the development directions and the habitat types with major impacts, and ascertaining whether impacts affect species with either low or high conservation and/or economic value. Generalization of the proposed methodology to other regions or species will require wildlife-habitat models adequate for SEA analyses, so that we also propose guidelines for the development and validation of these models.

Animals↗

PubMed1997

Clinical and methodological issues in antiemetic therapy: a worldwide survey of experts' opinions. Multinational Association of Supportive Care in Cancer.

During the 1995 Multinational Association of Supportive Care in Cancer (MASCC) Congress, a consensus conference was planned by the Subcommittee for Antiemetics. To define the topics to be discussed, a questionnaire containing both clinical and methodological issues was sent to 118 experts in 31 countries. The questionnaire contained 33 items on clinical and 19 items on methodological issues, and each response was rated on a 4-level categorical scale. The clinical issues were evaluated for interest, that is clinical importance, and feasibility, that is availability of sufficient data to make them suitable topics for the consensus conference. About 60% of questionnaires were returned, with a small number of missing responses. The responses to the items of clinical interest showed that about two-thirds of the issues identified by the Subcommittee were found by the experts to be of at least high interest, but often the availability of data was found to be insufficient for their discussion. Prevention of acute emesis induced by cisplatin and by moderately emetogenic chemotherapy and the optimal intravenous dose and schedule of the 5-HT3 receptor antagonists were the items with the highest interest and feasibility. The issues in the methodological section were also mostly found to be of at least high interest. The distinction between acute and delayed emesis, the evaluation of the persistence of antiemetic efficacy in subsequent cycles of chemotherapy and the statistical analysis of delayed emesis were the methodological issues in which the highest interest was recorded. Data collected will be used to define the main topics to be discussed during the planned consensus conference.

Antiemetics↗

PubMed2006

Development of clinical guidelines: methodological and practical issues.

The key elements for developing a clinical guideline are (a) guidelines are developed by multidisciplinary groups, (b) they are based on a systematic review of the scientific evidence, and (c) recommendations are explicitly linked to the supporting evidence and graded according to the strength of that evidence. Besides reporting the statistical strength of the randomised controlled trial results, it is necessary to consider the strength of the evidence, the methodological quality of the studies and the external validity by applying a "considered judgement" to the whole amount of the data. The Scottish Intercollegiate Guidelines Network (SIGN) process for developing guidelines is based on 4 steps: (a) methodological evaluation, (b) synthesis of evidence, (c) considered judgement and (d) grading system. The judgement on grading of recommendations is made on the basis of an (objective) assessment of the study design and quality, and a (perhaps more subjective) judgement of the consistency, clinical relevance and external validity of the evidence. The SPREAD group decided to adopt this methodology starting from the 3rd edition (2003); however, it was agreed to integrate the principles of the SIGN [4] with the statistical considerations on alpha and beta error size suggested by the Centre for Evidence-Based Medicine methodology [6], to give a more comprehensive evaluation of the available evidence. By being the product of a multidisciplinary approach, being explicit and providing information on the way agreement has been reached or on the reasons of disagreement, the SPREAD guidelines seem to fulfil the needs for shared guidelines, and to avoid the concerns related to pitfalls in the transparency of the process and in the reaching of a consensus.

Evidence-Based Medicine↗

PubMed2006

Spatial correlation analysis of isotropic microvessels: methodology and application to thyroid capillaries.

The study of relations between structural organization and functions of microcirculatory networks is a major aim of modern microangiology. Such a structural aspect of microvessels (MVs) as their spatial arrangement has substantial influence on their transport and other functional properties. This paper describes a methodology of spatial correlation analysis for isotropic blood and lymphatic MVs which is based on a stereological estimator of the pair correlation function [g3D(r)] created recently by the authors for systems of elongated objects. The following main features of the methodology are presented: (i) interpretation of the shape of g3D(r) curves, (ii) their quantitative description by numerical parameters, and (iii) limitations of the method arising from statistical requirements to MVs under investigation. The methodology is considered in the light of multilevel sampling designs, which are typical for biomedical morphology. The estimator with its methodological framework is applied to perifollicular blood capillaries in the adult rat thyroid. Related methods for studying the spatial arrangement of MVs are thoroughly discussed in the paper.

Albinism↗

PubMed2006

Detection of differential viewing patterns to erotic and non-erotic stimuli using eye-tracking methodology.

As a first step in the investigation of the role of visual attention in the processing of erotic stimuli, eye-tracking methodology was employed to measure eye movements during erotic scene presentation. Because eye-tracking is a novel methodology in sexuality research, we attempted to determine whether the eye-tracker could detect differences (should they exist) in visual attention to erotic and non-erotic scenes. A total of 20 men and 20 women were presented with a series of erotic and non-erotic images and tracked their eye movements during image presentation. Comparisons between erotic and non-erotic image groups showed significant differences on two of three dependent measures of visual attention (number of fixations and total time) in both men and women. As hypothesized, there was a significant Stimulus x Scene Region interaction, indicating that participants visually attended to the body more in the erotic stimuli than in the non-erotic stimuli, as evidenced by a greater number of fixations and longer total time devoted to that region. These findings provide support for the application of eye-tracking methodology as a measure of visual attentional capture in sexuality research. Future applications of this methodology to expand our knowledge of the role of cognition in sexuality are suggested.

Adult↗

PubMed2006

A water quality monitoring network design methodology for the selection of critical sampling points: part II.

In order to resolve the spatial component of the design of a water quality monitoring network, a methodology has been developed to identify the critical sampling locations within a watershed. This methodology, called Critical Sampling Points (CSP), focuses on the contaminant total phosphorus (TP), and is applicable to small, predominantly agricultural-forested watersheds. The CSP methodology was translated into a model, called Water Quality Monitoring Station Analysis (WQMSA). It incorporates a geographic information system (GIS) for spatial analysis and data manipulation purposes, a hydrologic/water quality simulation model for estimating TP loads, and an artificial intelligence technology for improved input data representation. The model input data include a number of hydrologic, topographic, soils, vegetative, and land use factors. The model also includes an economic and logistics component. The validity of the CSP methodology was tested on a small experimental Pennsylvanian watershed, for which TP data from a number of single storm events were available for various sampling points within the watershed. A comparison of the ratios of observed to predicted TP loads between sampling points revealed that the model's results were promising.

Environmental Monitoring↗

PubMed2006

A water quality monitoring network design methodology for the selection of critical sampling points: Part I.

The principal instrument to temporally and spatially manage water resources is a water quality monitoring network. However, to date in most cases, there is a clear absence of a concise strategy or methodology for designing monitoring networks, especially when deciding upon the placement of sampling stations. Since water quality monitoring networks can be quite costly, it is very important to properly design the monitoring network so that maximum information extraction can be accomplished, which in turn is vital when informing decision-makers. This paper presents the development of a methodology for identifying the critical sampling locations within a watershed. Hence, it embodies the spatial component in the design of a water quality monitoring network by designating the critical stream locations that should ideally be sampled. For illustration purposes, the methodology focuses on a single contaminant, namely total phosphorus, and is applicable to small, upland, predominantly agricultural-forested watersheds. It takes a number of hydrologic, topographic, soils, vegetative, and land use factors into account. In addition, it includes an economic as well as logistical component in order to approximate the number of sampling points required for a given budget and to only consider the logistically accessible stream reaches in the analysis, respectively. The methodology utilizes a geographic information system (GIS), hydrologic simulation model, and fuzzy logic.

Environmental Monitoring↗