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PubMed2001

Acoustic-phonetic features for the automatic classification of fricatives.

In this article, the acoustic-phonetic characteristics of the American English fricative consonants are investigated from the automatic classification standpoint. The features studied in the literature are evaluated and new features are proposed. To test the value of the extracted features, a statistically guided, knowledge-based, acoustic-phonetic system for the automatic classification of fricatives in speaker-independent continuous speech is proposed. The system uses an auditory-based front-end processing system and incorporates new algorithms for the extraction and manipulation of the acoustic-phonetic features that proved to be rich in their information content. Classification experiments are performed using hard-decision algorithms on fricatives extracted from the TIMIT database continuous speech of 60 speakers (not used in the design/training process) from seven different dialects of American English. An accuracy of 93% is obtained for voicing detection, 91% for place of articulation detection, and 87% for the overall classification of fricatives.

Algorithms↗

PubMed2001

A nonparametric scoring algorithm for identifying informative genes from microarray data.

Microarray data routinely contain gene expression levels of thousands of genes. In the context of medical diagnostics, an important problem is to find the genes that are correlated with given phenotypes. These genes may reveal insights to biological processes and may be used to predict the phenotypes of new samples. In most cases, while the gene expression levels are available for a large number of genes, only a small fraction of these genes may be informative in classification with statistical significance. We introduce a nonparametric scoring algorithm that assigns a score to each gene based on samples with known classes. Based on these scores, we can find a small set of genes which are informative of their class, and subsequent analysis can be carried out with this set. This procedure is robust to outliers and different normalization schemes, and immediately reduces the size of the data with little loss of information. We study the properties of this algorithm and apply it to the data set from cancer patients. We quantify the information in a given set of genes by comparing its distribution of the score statistics to a set of distributions generated by permutations that preserve the correlation structure among the genes.

Algorithms↗

PubMed2000

Evaluation of an algorithm for treatment of status epilepticus in adult patients undergoing video/EEG monitoring.

Convulsive or generalized tonic clonic status epilepticus (SE) is a neurological emergency that can lead to transient or permanent brain damage or even death. An algorithm was designed to aid nursing and medical staff members in decision making about the type of SE and pharmacological intervention needed to stop prolonged or repetitive seizures. Fifteen registered nurses at a northern New England medical center's epilepsy unit participated in educational sessions on classification of seizures and status epilepticus prior to use of the algorithm. A pretest-posttest design with an investigator-developed tool was used to measure SE knowledge before and after educational intervention. There was a significant improvement in scores on the posttest of the classification of status epilepticus (Z = -2.93, p = .003). Twenty-nine medical records of patients who had experienced SE between February 1992 and December 1997 were reviewed. Nineteen patients experienced SE before the algorithm was implemented, and 10 patients experienced SE after the algorithm was implemented. A total of 16 patients experienced generalized convulsive SE with 12 episodes occurring before and 4 episodes after algorithm implementation. The mean time taken to stop the episode of SE after pharmacologic treatment began was compared in both groups using a t-test. The mean difference between the groups was 235 minutes (t = 2.57, p = .026). The findings of this project demonstrate that combining a treatment algorithm with education of staff members on its use has benefits in the practice setting of an inpatient comprehensive epilepsy program. Episodes of SE are more accurately classified and successful treatment of the episodes occurs earlier.

Adolescent↗

PubMed1989

Algorithmic sequential decision-making in the frequency domain for life threatening ventricular arrhythmias and imitative artefacts: a diagnostic system.

A preliminary study to approach the problem of reliably detecting life threatening ventricular arrhythmias in real time is described. An algorithm (DIAGNOSIS) has been developed in order to classify ECG signal records on the basis of the computation of four simple parameters calculated from a representation in the frequency domain. This algorithm uses a set of rules constituting an operative classification scheme based on the comparison of the parameters with a set of pre-established thresholds. This allows us to differentiate four general categories: ventricular fibrillation-flutter, ventricular rhythms, imitative artefacts and predominant sinus rhythm.

Algorithms↗

PubMedDate not supplied

[Mathematical modelling and the prognosis of treatment efficacy in papillomavirus infection of the cervix uteri].

In this paper, consideration is given to the problem of mathematical modelling, diagnosis and effects of treatment options on the condition of a patient exposed to papillomavirus infection. The problem is tackled of identifying the most prominent signs of degree of severity of the disease course and of therapy efficiency on the basis of parameters characterizing the immunologic vigor with making use of the covariation matrix eigenvalues algorithm, namely the modelling manifolds algorithm. Such an approach allows the central problem of classification of indices for the immunologic vigor to be settled. A mathematical model as discrimination surface to be used for prediction of results of the treatments administered is constructed.

Algorithms↗

PubMed2001

A proposed taxonomy for nailfold capillaries based on their morphology.

Certain diseases cause permanent changes to the shapes and densities of nailfold capillaries and, therefore, nailfold capillaroscopy is important as a tool for diagnosing and monitoring these diseases. The first aim of the project is to resolve differences in terminology that have developed over the years in previous work. We propose a taxonomy for nailfold capillaries that cover six descriptive classes: cuticulis, open, tortuous, crossed, bushy, and bizarre. The first three are parametric in that they may be distinguished by the ratio of capillary length to width and by the curvature of the capillary limbs. The last three are characterized by their topology; a crossed capillary has a closed area that is not connected to the image background. Bushy and bizarre capillaries have atypical shapes that are characterized by the convex hull of their skeleton. These descriptive classes may be modified according to anomalies in width and length. The second aim is to automate the classification of capillaries by encapsulating the taxonomy in an algorithm; our computer program rivals the most experienced clinicians in classifying capillaries consistently with an overall agreement of 85% with the clinicians' majority view. This was particularly valuable in classifying borderline shapes objectively and consistently.

Capillaries↗

PubMed1994

Automated peak detection and cell cycle analysis of flow cytometric DNA histograms.

We describe an algorithm for fully automated flow cytometric DNA histogram classification and analysis that provides rapid, reproducible determination of DNA index and S-phase fraction (SPF). Automated classification agreed with subjective assessment of DNA ploidy in 96-98% of DNA histograms. Automated and conventional analyses of DNA index (r = 0.95) and SPF (r = 0.89) were also highly correlated with one another. In a series of 86 node-negative breast carcinomas, SPF calculated with the fully automated method was a significant predictor of 10 year survival (p = 0.009). Automation greatly increased the speed of DNA histogram analysis, allowing evaluation of the same set of histograms with different methods. In a preliminary study exploring the optimization of DNA histogram analysis, the best association between SPF and prognosis of breast cancer patients was achieved using sliced nuclei debris modeling, reporting only the aneuploid SPF (in aneuploid histograms), while excluding small aneuploid clones (< 15% of total cell count) from evaluation. In conclusion, automated DNA histogram analysis does not replace the need for close human supervision but provides a useful guideline for less experienced users, facilitates interlaboratory comparisons, and makes possible extensive reanalyses of large data sets.

Breast Neoplasms↗

PubMedDate not supplied

Quantitative self-organizing maps for clustering electron tomograms.

Tomography emerges as a powerful methodology for determining the complex architectures of biological specimens that are better regarded from the structural point of view as singular entities. However, once the structure of a sufficiently large number of singular specimens is solved, quite possibly structural patterns start to emerge. This latter situation is addressed here, where the clustering of a set of 3D reconstructions using a novel quantitative approach is presented. In general terms, we propose a new variant of a self-organizing neural network for the unsupervised classification of 3D reconstructions. The novelty of the algorithm lies in its rigorous mathematical formulation that, starting from a large set of noisy input data, finds a set of "representative" items, organized onto an ordered output map, such that the probability density of this set of representative items resembles at its possible best the probability density of the input data. In this study, we evaluate the feasibility of application of the proposed neural approach to the problem of identifying similar 3D motifs within tomograms of insect flight muscle. Our experimental results prove that this technique is suitable for this type of problem, providing the electron microscopy community with a new tool for exploring large sets of tomogram data to find complex patterns.

Algorithms↗

PubMed1997

Fractal texture analysis in computer-aided diagnosis of solitary pulmonary nodules.

RATIONALE AND OBJECTIVES: The authors investigated the use of fractal texture characterization to improve the accuracy of solitary pulmonary nodule computer-aided diagnosis (CAD) systems. METHODS: Thirty chest radiographs were acquired from patients who had no pulmonary nodules. Thirty regions were selected that were considered remotely suspicious-looking for nodules. Artificial nodules of multiple shapes, sizes, and orientations were added at subtle levels of contrast to 30 non-suspicious-looking regions of the radiographs. Fractal dimensions of the 60 "nodule candidates" were calculated to quantify the texture of each region. Four radiologists also interpreted the images. RESULTS: The fractal dimension of each possible nodule provided statistically significant (P < .05) differentiation between regions that contained an artificial nodule and those that did not. The area under the receiver operating characteristic curve for the fractal analysis was significantly better (P < .05) than that for the radiologists. CONCLUSION: Fractal texture characterization provides useful information for the classification of potential solitary pulmonary nodules with CAD algorithms.

Diagnosis, Computer-Assisted↗

PubMed2000

Chromosome identification using hidden Markov models: comparison with neural networks, singular value decomposition, principal components analysis, and Fisher discriminant analysis.

The analysis of G-banded chromosomes remains the most important tool available to the clinical cytogeneticist. The analysis is laborious when performed manually, and the utility of automated chromosome identification algorithms has been limited by the fact that classification accuracy of these methods seldom exceeds about 80% in routine practice. In this study, we use four new approaches to automated chromosome identification--singular value decomposition (SVD), principal components analysis (PCA), Fisher discriminant analysis (FDA), and hidden Markov models (HMM)--to classify three well-known chromosome data sets (Philadelphia, Edinburgh, and Copenhagen), comparing these approaches with the use of neural networks (NN). We show that the HMM is a particularly robust approach to identification that attains classification accuracies of up to 97% for normal chromosomes and retains classification accuracies of up to 95% when chromosome telomeres are truncated or small portions of the chromosome are inverted. This represents a substantial improvement of the classification accuracy for normal chromosomes, and a doubling in classification accuracy for truncated chromosomes and those with inversions, as compared with NN-based methods. HMMs thus appear to be a promising approach for the automated identification of both normal and abnormal G-banded chromosomes.

Chromosome Mapping↗

PubMedDate not supplied

In vivo myeloarchitectonic analysis of human striate and extrastriate cortex using magnetic resonance imaging.

A primary goal of investigations into the organization of human cerebral cortex is to determine the functional specificity of architectonic regions. This includes the correlation of neurobehavioral deficits with neuropathological data for clinical diagnosis and treatment, and the identification of active brain regions using functional neural imaging techniques, such as positron emission tomography, electroencephalographic and magnetoencephalographic (EEG and MEG) source localization algorithms, and direct cortical stimulation. Currently, the architectonic classification of a cortical region identified by these methods is inferred from the comparison of its cerebral topographic position to cytoarchitectonic brain atlases. However, substantial intersubject variability in the position of cytoarchitectonic regions with respect to cerebral topographic landmarks may lead to errors in this procedure. An alternative method is presented here, which uses magnetic resonance (MR) imaging to identify myeloarchitectonic regions of isocortex directly by estimating the relative concentration of myelin within cortical laminae. This high-resolution MR protocol is used to identify striate cortex (Brodmann's area 17) and extrastriate cortex in vivo. Correspondence of MR signal intensity with myeloarchitectonic data from a postmortem brain confirms this identification. As MR imaging technology improves, this noninvasive method has the potential to identify and discriminate among at least 50 cortical regions in the living human brain.

Female↗

PubMed1985

Uterine perforation and embedding by intrauterine device: evaluation by US and hysterography.

Uterine perforation and deep embedding by an intrauterine device (IUD) require exact determination of its location as a necessary step to safe and effective retrieval. Six cases of uterine perforation and four of embedding by an IUD were studied with ultrasonography (US) and hysterography. While US findings suggested the correct diagnosis of perforation in five of the six cases, hysterography yielded more exact diagnostic information. Deep embedding could only be diagnosed with hysterography. A classification of the types of perforation and an algorithm for diagnosing ectopic IUD are presented. Undue reliance on the sonographic appearance of an IUD in the center of the uterine image may lead to hazardous attempts at transvaginal removal of a device that is partly intramural. In this study, hysterography offered the most precise diagnostic information.

Adult↗

PubMed2001

Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization.

Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization. Physiol Genomics 7: 135-148, 2001. First published September 21, 2001; 10.1152/physiolgenomics.00061.2001.-Human decidual fibroblasts undergo a differentiative commitment to the acquisition of endocrine, metabolic, and structural cell functions in a process known as decidualization. Decidualization is critical for embryo implantation and placental function. We characterized gene expression pattern kinetics during decidual fibroblast differentiation by microarray analysis. Of 6,918 genes analyzed, 121 genes were induced by more than twofold, 110 were downregulated, and 50 showed biphasic behavior. Dynamically regulated genes were could be fit into nine K-means algorithm-based kinetic pattern groups, and by biologic classification, into five categories: cell and tissue function, cell and tissue structure, regulation of gene expression, expressed sequence tag (EST), and "function unknown." Reprogramming of genes within specific functional groups and gene families was a prominent feature that consisted of simultaneous induction and downregulation of a set of genes with related function. We previously observed a conceptually similar process during fetal trophoblast differentiation, in which the same phenomena applied to different genes. Of the 569 dynamically regulated genes regulated by either model, only 81 of these were in common. These results suggest that reprogramming of gene expression within focused functional categories represents a fundamental aspect of cellular differentiation.

Cell Differentiation↗

PubMed1985

Berner's axial syndromes and the polydiagnostic approach of the LICET system.

The LICET system is a polydiagnostic instrument permitting recording of diagnostic criteria and assignment by diagnostic algorithms as proposed in a number of different classification systems, including the Viennese Research Criteria. In the present report, French diagnostic practices are compared with the Viennese Research Criteria for endogenomorphic-schizophrenic and endogenomorphic-cyclothymic axial syndromes.

Austria↗

PubMed2000

Health-related quality of life in survivors of Wilms' tumor and advanced neuroblastoma: aA cross-sectional study.

PURPOSE: In pediatric oncology, Wilms' tumor and advanced neuroblastoma represent opposite ends of the spectra of survival probability and therapeutic intensity. Consequently, it was envisaged that survivors of Wilms' tumor would enjoy better health status and health-related quality of life (HRQL) than survivors of advanced neuroblastoma. PATIENTS AND METHODS: Health status questionnaires were sent to the parents of all eligible children and to the children themselves if they were > or = 8 years of age. Responses were received from 84% of 93 eligible families. Responses were converted by established algorithms into levels of two multiattribute health status classification systems known as Health Utilities Index Mark 2 and Mark 3. These systems are linked to measures of preference, in the form of multiattribute utility functions, which provide scores of morbidity for single-attribute levels and of global HRQL for comprehensive health states. RESULTS: A greater burden of morbidity was identified in the survivors of advanced neuroblastoma than in survivors of Wilms' tumor based on the assessments of the parents of these children. In particular, survivors of advanced neuroblastoma exhibited deficits in hearing and speech. It is possible that this morbidity burden reflects the prevalent use of platinum compounds (causing ototoxicity) in this group. Within parent-child dyads there was a high level of percentage agreement on responses in all attributes except cognition. CONCLUSION: Extension of this study to a larger sample size of patients will provide clarification of these observations.

Adolescent↗

PubMed2002

Comparative studies on Aeromonas strains isolated from Lakes Balaton (Hungary) and Fertó/Neusiedlersee (Hungary).

Ecological and comparative taxonomic investigations were carried out on 49 Aeromonas strains isolated from water samples of two moderately alkaline lakes of Hungary, Lake Balaton and Lake Fertó/Neusiedlersee together with 3 authentic strains of Aeromonas hydrophila. Five phena were created at greater than 92% similarity value using the UPGMA method with the Jaccard coefficient. Strains isolated from Lake Balaton were determined as A. hydrophila, while strains originated from Lake Fertó were identified as A. hydrophila and A. sobria. The Fertó isolates of A. hydrophila grew only at higher salt concentration (5% NaCl). This might be an adaptation to the higher salt contents in the water of Lake Fertó. However, no specific differences were detected in their behaviour against alkaline pH values. The wide range of their degradative enzymes indicate that aeromonads can play an important role in nutrient cycling.

Aeromonas↗

PubMed1992

Assessing and understanding patient risk.

Nonsteroidal anti-inflammatory drug (NSAID) gastropathy is the most frequent and one of the most severe drug side effects in the United States. NSAID-associated gastropathy has been estimated to account for at least 7600 deaths and 76000 hospitalizations each year in the United States alone. Hospitalizations in rheumatoid arthritis patients occurred in 1.6% of patients; for patients with osteoarthritis the incidence appears to be substantially lower. This is based on a consecutive series of 3000 patients with rheumatoid arthritis who were followed prospectively for an average of five years by ARAMIS, the Arthritis, Rheumatism and Aging Medical Information System. Multivariate analyses assessing risk factors for serious gastrointestinal (GI) events were performed on 1694 rheumatoid arthritis patients taking NSAIDs. The most important risk factors of higher age, use of prednisone, previous NSAID GI side effects, prior GI hospitalization, functional disability (based on the American Rheumatism Association classification), and NSAID dose are variables in an algorithm which estimates the risk of a serious GI event occurring in the next 12 months. Knowledge of risk factors and their interrelationships provides a tool for identifying patients at high risk and guides therapeutic decisions.

Aging↗

PubMedDate not supplied

The relationship between self-efficacy, attitudes, intake compared to others, consumption, and stages of change related to fruit and vegetables.

PURPOSE: This study examined whether eating practices and psychosocial factors differed across stages of change for fruit and vegetables. DESIGN: Data were collected using a self-administered written survey among a convenience sample of 739 Dutch adults. Response rate was 92%. SETTING: Data were collected as part of the baseline assessment for a nutrition intervention study. MEASURES: Fruit and vegetable intake was measured as self-reported consumption with a validated eight-item food frequency questionnaire. Psychosocial variables were measured with six items on bipolar seven-point scales and stage-of-change classifications were based on separate four-item algorithms for fruits and vegetables. Differences in psychosocial factors and consumption were analyzed using one-way analysis of variance with Scheffé's multiple-comparison test. RESULTS: Significant differences were found between stages of change in dietary intake, attitudes, self-efficacy, and judgment of one's own intake compared to others. Attitudes were most positive in preparation and action and least positive in precontemplation. Intake and self-efficacy were more positive in action/maintenance than in pre-action stages. CONCLUSIONS: The findings suggest that nutrition education aimed at encouraging higher intake of fruits and vegetables might be most effective if it is stage-tailored. Messages to influence attitudes about fruits and vegetables are likely to affect people in precontemplation, and self-efficacy information to increase confidence in overcoming barriers to consumption is likely to be effective with persons in contemplation and preparation stages.

Adult↗