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At least 73 records · Page 4Linked to original sources
PubMed1990

Factors affecting prognosis of intrauterine hydrocephalus diagnosed in the third trimester--computerized data analysis on controversies in fetal surgery.

Twenty hydrocephalic patients diagnosed in the third trimester of fetal life were evaluated and followed during a 7-year period. The factors affecting the prognosis, including the type of hydrocephalus, underlying conditions, associated anomalies, time of diagnosis and delivery, fetal period after diagnosis, head circumference and degree of ventriculomegaly at birth, and age at treatment, were comprehensively analyzed. The difference between final outcomes as assessed by developmental quotient (DQ) or intelligence quotient (IQ) were statistically tested with computation by means of STAX packages in an NEC 9801 VX. Hydrocephalus as an isolated defect occurred in six cases (30%), was associated with other central nervous system anomalies in nine (45%), and was secondary to intrauterine intraventricular hemorrhage or brain tumor in five (25%). The average age at the time of diagnosis was 33.9 weeks of gestation (range, 27-40 weeks). One fetus was treated by transabdominal cephalocentesis, but the majority of patients underwent ventriculoperitoneal shunt postnatally. The final IQ or DQ scores ranged from 20 to 120 (mean score, 50.6). The data analyses revealed that the only significant factor affecting outcome was the fetal period after diagnosis of hydrocephalus (r = -0.5076, p less than 0.01). Our data supports the fact that the results of an on-going hydrocephalic state may become irreversible during fetal life. It is emphasized that establishment of a more precise pathophysiological evaluation, and a less invasive but more reliable decompressive technique for fetal hydrocephalus, is urgent.

Chi-Square Distribution↗
PubMedDate not supplied

Comparison between manual and automatic coding of medical record statistical cards at a university hospital.

The coding error rate of systems for medical record statistical cards (MRSCs) throughout health services is about 30%. A program using automatic coding has been developed at the Institute of Clinical Surgery II, Padua University Hospital, with a view to reducing this percentage. Out of an overall sample of 4776 MRSCs from all departments of the hospital, 54 were automatically coded at our institute. Categories of discrepancy between the discharge diagnosis codes of the 4722 manually coded MRSCs and the other 54 MRSCs were classified as follows: types I-III, diagnosis assigned to an erroneous under-class, class or heading (ICD-9) respectively; type IV, incorrect diagnosis formulation precluding code assignment; type V, two or more discrepancies on MRSC; and type VI, secondary diagnosis not coded. Discrepancy rates were as follows: 22.3% and 0.0% for type I; 21.3% and 0.0% for type II; 17.6% and 0.0% for type III; 1.9% and 0.0% for type IV; 5.8% and 0.0% for type V; 31% and 1.9% for type VI. Code discrepancy rates for surgical procedures, which were also compared, ranged from 7.0 to 12.5% for manual coding, while no discrepancy was observed in automatically-coded MRSCs. The results clearly demonstrate the utility of the system reported on, and it is suggested that it should be used in a modified form in other hospital departments.

Abstracting and Indexing↗
PubMed1989

Ternary representation of trivariate data.

A new fast trivariate display technique based on the ratio of three measured variables and of relative cell number, obtained from flow cytometric measurements, is described.

Data Interpretation, Statistical↗
PubMed1991

Localized 1H NMR spectroscopy in patients with chronic hepatic encephalopathy. Analysis of changes in cerebral glutamine, choline and inositols.

Localized, short echo 1H magnetic resonance spectra from an area in the parietal cortex of three patients suffering from chronic hepatic encephalopathy are compared with equivalent spectra obtained from healthy control subjects. Three significant differences are found: elevated glutamine, decreased inositol, and decreased choline peak intensities. The elevation of cerebral glutamine concentration is expected as a consequence of the presumed chronic hyperammonemia in this disease. The finding of a 50% change in the inositol peak is physiologically unexpected and so far unaccounted for. Data acquisition and processing parameters are described in detail. To further define spectral abnormalities, which were readily detected in untransformed spectra, a simple data analysis scheme has been used that consists of post-acquisition low-frequency filtering, a lineshape transformation, and a difference technique to clarify spectral changes.

Aged↗
PubMed2001

A knowledge-based, concept-oriented view generation system for clinical data.

Information overload is a well-known problem for clinicians who must review large amounts of data in patient records. Concept-oriented views, which organize patient data around clinical concepts such as diagnostic strategies and therapeutic goals, may offer a solution to the problem of information overload. However, although concept-oriented views are desirable, they are difficult to create and maintain. We have developed a general-purpose, knowledge-based approach to the generation of concept-oriented views and have developed a system to test our approach. The system creates concept-oriented views through automated identification of relevant patient data. The knowledge in the system is represented by both a semantic network and rules. The key relevant data identification function is accomplished by a rule-based traversal of the semantic network. This paper focuses on the design and implementation of the system; an evaluation of the system is reported separately.

Artificial Intelligence↗
PubMed1997

Technique for importing greater evolution resolution in multidimensional NMR spectrum.

A very simple and general procedure that extracts constant-evolution-frequency data from a truncated multidimensional (2D, 3D, 4D, etc.) FID is described, generalized, analyzed, and illustrated. The method replaces Fourier transformation of the evolution dimension with a linear model created from a separate, high-quality 1D FID. The equivalent of high resolution in the evolution dimension can be achieved without obtaining an extensive multidimensional FID. The analysis of the 1D FID can also be used to predict the signal to noise ratio of the extracted slices that will result from various evolution dimension sampling protocols, making it possible to develop a priori an optimal sampling strategy for the multidimensional FID. The evolution dimension need not be sampled periodically. The procedure has a potential signal-to-noise ratio advantage because it extracts usable information from a multidimensional FID at short evolution times before the magnetization has decayed significantly.

Data Interpretation, Statistical↗
PubMed1996

Stepwise regression is an alternative to splines for fitting noisy data.

In this study, we compared numerical methods that are used to fit noisy data. Comparisons included polynominal regression, stepwise polynomial regression and quintic spline approximation. The advantages and limitations of each method are discussed in terms of curve fit quality, computational speed and ease, and solution compactness. Overall, the spline approximation and stepwise polynomial regression provide the best fits to the data. Stepwise regression provides the added utility of providing a simple, unconstrained function which can be easily implemented in simulation studies.

Algorithms↗
PubMed1993

A method for measuring and reporting manual data extraction reliability.

As health care costs have risen dramatically, the use of clinical data to analyze the quality of health care provided has increased. Central to this analysis is the means by which the clinical data itself is obtained. The reliability and validity of the data must be established in order to insure credible use of the data. The Wisconsin Ambulatory Review Project (WARP) is a three-year study of the nature of care in the ambulatory setting based on clinical data extracted retrospectively from written medical charts. This paper focuses on the method used to measure and report the reliability of the extraction process in the WARP study. The implementation of this methodology as a custom C program is described in detail.

Ambulatory Care↗
PubMed1989

A computer-assisted procedure for the assembly and analysis of short-term genotoxicity test data.

Determining the genetic hazard of a chemical is generally approached by using an assortment of tests for measuring the DNA reactivity of a chemical or its resultant genotoxicity. Over 100 short-term tests employing a wide diversity of species and genetic mechanisms have been used to measure genetic hazard. To date, attempts to achieve a standard test battery for defining genetic hazard have not been successful. Consequently, testing for genetic hazard involves the use of test batteries with variable types and numbers of assays. This increases the difficulties of interpreting data sets since the data sets are often filled with inconsistent responses from diverse types of assays. Several years ago, the International Commission for Protection Against Environmental Mutagens and Carcinogens (ICPEMC) established a Committee to develop a method to compile and interpret diverse short-term test data. The Committee has produced a quantitative weight-of-evidence approach that combines test data using certain parameters such as dose, replication, and metabolic capacity into a series of scores for test type, test class, test family, and an overall score that defines the total weight-of-evidence regarding the genetic hazard of the agent. A description of the method and results from the evaluation of selected chemicals is provided.

Animals↗
PubMedDate not supplied

SLEUTH--a fast computer program for automatically detecting particles in electron microscope images.

A method has been developed to locate biological complexes in a digitized electron micrograph by matching small windows to a set of reference images using a series of simple criteria. From the reference images, the program calculates parameters such as the radius of gyration, the density sum and variance. It compares them with corresponding values from a moving square window of densities extracted from the micrograph and records the coordinates of successfully matched candidate squares. Since the same particle is detected in a series of overlapping windows, candidates found to be within close proximity are grouped and the best-fitting one is selected from each cluster. The user is required only to select a small stack of boxed reference images and provide a few parameters, such as the particle radius and the minimum acceptable distance between particle centres. Micrograph labels and other areas that do not contain appropriate specimens are automatically ignored in order to minimize false positives. The program has been tested successfully on a variety of different biological structures, from both negatively stained and ice-embedded specimens.

Analysis of Variance↗
PubMedDate not supplied

A two step approach for semi-automated particle selection from low contrast cryo-electron micrographs.

Over recent years advances in cryo-electron microscopy for the study of macromolecular structure have resulted in resolutions in the range 10-15 A becoming routine. With this drive for increased resolution comes the need to collect larger datasets, commonly >10,000 particle images. Manual selection of particles from micrographs is often difficult and with such large numbers of particles now involved it is also laborious and a common bottleneck. Automated methods do exist but are normally restricted to specific samples or data, i.e., spherical particles, no aggregation, high contrast, and low noise. A two step approach has been developed that remains general and can be applied to low contrast, high noise micrographs of small molecules. Specifically, application of the approach is presented using micrographs of Escherichia coli RNA polymerase, which due to low contrast and the relatively small size of the molecule prove difficult to pick manually. To test the automated approach, independent reconstructions of RNA polymerase were carried out using manual and automatically picked data. The two reconstructions are shown to be comparable and the reconstruction from the automatically picked dataset is at a higher resolution, due to an increase in the number of particles picked.

Algorithms↗
PubMedDate not supplied

Detecting circular and rectangular particles based on geometric feature detection in electron micrographs.

Accurate and automatic particle detection from cryo-electron microscopy (cryo-EM images) is very important for high-resolution reconstruction of large macromolecular structures. In this paper, we present a method for particle picking based on shape feature detection. Two fundamental concepts of computational geometry, namely, the distance transform and the Voronoi diagram, are used for detection of critical features as well as for accurate location of particles from the images or micrographs. Unlike the conventional template-matching methods, our approach detects the particles based on their boundary features instead of intensities. The geometric features derived from the boundaries provide an efficient way for locating particles quickly and accurately, which avoids a brute-force searching for the best position/orientation. Our approach is fully automatic and has been successfully applied to detect particles with approximately circular or rectangular shapes (e.g., KLH particles). Particle detection can be enhanced by multiple sets of parameters used in edge detection and/or by anisotropic filtering. We also discuss the extension of this approach to other types of particles with certain geometric features.

Algorithms↗
PubMedDate not supplied

Application of template matching technique to particle detection in electron micrographs.

Template matching together with the comprehensive theory of image formation in electron microscope provides an optimal (in Bayesian sense) tool for solving one of the outstanding problems in single particle analysis, i.e., automatic selection of particle views from noisy micrograph fields. The method is based on the assumption that the reference three-dimensional structure is known and that the relevant parameters of the model of the image formation process can be estimated. In the first stage of the procedure, a set of possible particle views is generated using the available reference structure. The template images are constructed as linear combinations of available particle views using a clustering technique. Next, the micrograph noise characteristic is established using an automated contrast transfer function (CTF) estimation procedure. Finally, the CTF parameters calculated are used to construct a matched filter and correlation functions corresponding to the available template images are calculated. In order to alleviate the problem of the biased caused by varying image formation conditions, a decision making strategy based on the predicted distribution of correlation coefficients is proposed. It is demonstrated that due to the inclusion of CTF considerations, the template matching method performed very well in a broad range of microscopy conditions.

Algorithms↗
PubMedDate not supplied

An approach to automated particle picking from electron micrographs based on reduced representation templates.

Reduced representation templates are used in a real-space pattern matching framework to facilitate automatic particle picking from electron micrographs. The procedure consists of five parts. First, reduced templates are constructed either from models or directly from the data. Second, a real-space pattern matching algorithm is applied using the reduced representations as templates. Third, peaks are selected from the resulting score map using peak-shape characteristics. Fourth, the surviving peaks are tested for distance constraints. Fifth, a correlation-based outlier screening is applied. Test applications to a data set of keyhole limpet hemocyanin particles indicate that the method is robust and reliable.

Algorithms↗
PubMed2006

Global environmental data for mapping infectious disease distribution.

This contribution documents the satellite data archives, data processing methods and temporal Fourier analysis (TFA) techniques used to create the remotely sensed datasets on the DVD distributed with this volume. The aim is to provide a detailed reference guide to the genesis of the data, rather than a standard review. These remotely sensed data cover the entire globe at either 1 x 1 or 8 x 8 km spatial resolution. We briefly evaluate the relationships between the 1 x 1 and 8 x 8 km global TFA products to explore their inter-compatibility. The 8 x 8 km TFA surfaces are used in the mapping procedures detailed in the subsequent disease mapping reviews, since the 1 x 1 km products have been validated less widely. Details are also provided on additional, current and planned sensors that should be able to provide continuity with these environmental variable surfaces, as well as other sources of global data that may be used for mapping infectious disease.

Communicable Diseases↗
PubMed1998

Solar cycle variation of the low-altitude trapped proton flux.

Under NASA's Space Environment Effects (SEE) program, we are developing new models for the low-altitude (250-1000 km, L < 1.5) trapped radiation environment based on data from the TIROS/NOAA polar orbiting spacecraft. The unique features of this data base and model include the long time series (more than one complete solar cycle) obtained from the TIROS/NOAA data and the use of a coordinate system more applicable to the low-altitude environment. The data show a strong variation (as much as a factor of 10) over the solar cycle and a hysteresis effect between the rising and falling portions of the solar cycle. Both the solar cycle variation and the hysteresis are functions of L. In addition to the hysteresis effect, the flux during a given cycle appears to be a function of the previous cycle. Superimposed on the gradual variation over the solar cycle, transient effects, correlated with solar particle events (SPEs), can be clearly seen. Comparison with the AP8 models shows that the measured flux is a factor of 2-3 higher than the model. These data have important implications for the development and use of trapped radiation models, and will also contribute to our knowledge of the source and loss mechanisms at work in the inner zone

Atmosphere↗
PubMed1997

Views on local data management in cancer clinical trials.

The randomized clinical trial is the ultimate method of establishing the value of any new cancer treatment, but the percentage of patients with cancer in the UK who are included in clinical trials of any sort is in single figures. The reasons for this low figure include both patient and clinician factors. The extra work involved in trials is cited repeatedly by clinicians as the main reason for not entering patients into cancer clinical trials. This paper discusses how the provision of local data management could be one important way to improve recruitment into and to ensure the smooth running of clinical trials.

Clinical Trials as Topic↗