Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “classifier”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMed1990

Analysis of protein synthesis in morphologically classified bovine follicular oocytes before and after maturation in vitro.

Bovine cumulus oocyte complexes (COCs) were isolated from antral ovarian follicles (4-8 mm). Immature COCs were classified into four categories, based on the homogeneity and clearness of the ooplasm and the transparency and compactness of the cumulus investment. In this study, the incorporation of TCA-precipitable 35S-methionine and the protein synthesis patterns of oocytes of these four categories were examined. Before maturation in vitro, similar incorporation rates and identical protein synthesis patterns were observed between oocytes of categories 1-3. Immature oocytes of category 4 showed reduced incorporation rates and exhibited aberrant protein synthesis patterns. After maturation in vitro, the patterns of category 4 oocytes were identical with the patterns of those in categories 1-3. The incorporation of 35S-methionine into in vitro matured oocytes was lower (P less than .001) in all categories. Based on these results, it is concluded that the initial classification of oocytes into four categories can be reduced to two categories.

Animals↗
PubMedDate not supplied

Headspace-solid-phase microextraction fast GC in combination with principal component analysis as a tool to classify different chemotypes of chamomile flower-heads (Matricaria recutita l.).

Headspace-solid-phase microextraction gas chromatography-principal component analysis (HS-SPME GC-PCA) is proposed as a complementary or alternative method to essential oil (EO) GC-PCA in order to discriminate between flower-heads of chamomile of different chemotypes. Ninety-two EOs and the headspaces sampled by HS-SPME of the corresponding chamomile flower-heads were examined by conventional GC and fast GC (F-GC) and the results submitted to statistical analysis by PCA. HS-SPME F-GC-PCA showed itself to be a rapid technique by which to distinguish chamomile flower-head chemotypes a produced results in agreement with the accepted EO classification. Using this method, the analysis time was reduced from at least 4.5 h with EO conventional GC to less than 1 h with HS-SPME F-GC. This approach can thus successfully be used as an analytical decision maker in order to reduce the number of time-consuming EO conventional GC analyses by limiting them to those samples that cannot unequivocally be classified. The EO conventional GC and HS-SPME F-GC results of PCA were very uniform, but they did not provide quantitative correlations between the components as determined by the two methods. A different statistical approach and a larger number of samples will be needed in order to correlate components in the headspace sampled by SPME and those in the corresponding EO quantitatively through a function.

Chromatography, Gas↗
PubMed2000

Mammalian deoxyribonucleases I are classified into three types: pancreas, parotid, and pancreas-parotid (mixed), based on differences in their tissue concentrations.

Deoxyribonuclease I (DNase I) activities were measured in 14 different tissues from humans and 5 other mammals (bovine, pig, rabbit, rat, and mouse) by using the single radial enzyme diffusion (SRED) method, which is a sensitive and nonradioactive assay for nucleases. The results indicated that these species are classifiable into three groups on the basis of their different tissue distributions of DNase I. In human and pig, the pancreas showed the highest activity of DNase I; in rat and mouse, the parotid glands showed the highest activity; and in bovine and rabbit, both pancreas and parotid glands showed high activity. Therefore we designated human and pig DNase I as pancreas type, rat and mouse DNase I as parotid type, and bovine and rabbit DNase I as pancreas-parotid (or mixed) type. DNase I of the pancreas type was more sensitive to low pH than the other types. DNase I of pancreas type is secreted into the intestinal tract under neutral pH conditions, whereas the other types are secreted from the parotid gland and have to pass through the very acidic conditions in the stomach. Differences in the tissue distribution and acid sensitivity of mammalian DNases I may provide important information about their digestive function from the evolutionary perspective.

Acids↗
PubMed1997

Evaluation of QRS morphological classifiers in the presence of noise.

This paper analyzes the performance of four similarity measures (distances: d1, d2, and dinfinity, as well as correlation coefficient), when they are employed for morphological classification of QRS complexes by means of linear cluster formation. An important characteristic that any morphological classification method for QRS complexes should possess is the ability to perform waveform recognition despite the wide variety in which these could appear, as well as the diverse types of noise that could contaminate the signal. Evaluation of these classifiers constitutes an important problem for their selection. Evaluation was performed using electrocardiographic signals selected from the MIT-BIH database. These signals were contaminated with several noise types that are found in the environment where electrocardiograms are usually registered and processed, and the different noise waveforms were combined in an appropriate way to simulate practical situations, including some with severe noise contamination. Results are expressed in terms of probabilities of correct classification for different signal to noise ratios, allowing a comparison between the different distance measures in terms of their effectiveness.

Algorithms↗
PubMed2005

Two methods for validating brain tissue classifiers.

In this paper, we present an evaluation of seven automatic brain tissue classifiers based on level of agreements. A number of agreement measures are explained, and we show how they can be used to compare different segmentation techniques. We use the Simultaneous Truth and Performance Level Estimation (STAPLE) of Warfield et al. but also introduce a novel evaluation technique based on the Williams' index. The methods are evaluated using these two techniques on a population of forty subjects, each having an SPGR scan and a co-registered T2 weighted scan. We provide an interpretation of the results and show how similar the output of the STAPLE analysis and Williams' index are. When no ground truth is required, we recommend the use of Williams' index as it is easy and fast to compute.

Algorithms↗
PubMed1996

Applying locally optimal criterion for classifying highly-reliable products with a control.

At the research and development stage, decision-makers may wish to classify several competing designs with respect to a control (or standard) one. The classification problem may become very difficult when the products are highly reliable, since only a few (or even no) failures may be observed under normal use condition. The accelerated life test model resolves this difficulty by shortening the time of life testing and quickly provides life data of products. For highly-reliable products with a Weibull log-linear model, we propose a classification rule based on a locally optimal criterion. A suitable sampling plan based on this rule is also developed. The performance of this rule is compared with a pairwise comparison classification rule. It is shown that the sample sizes needed for the new rule are considerably lower than those needed for the pairwise comparison rule.

Algorithms↗
PubMed1996

Potential contribution of optional urease-positive bacteria to idiopathic urinary calcium stone formation. I. Expression of urease activity in bacteria from the urinary tract that are commonly classified as urease-negative.

The aetiology of calcium oxalate stones, which are commonly believed to be sterile, has not yet been fully elucidated. Recent bacteriological studies and investigations using the scanning electron microscope have also shown microorganisms to be present in this type of stone. These microorganisms were assumed not to be able to split urea. To list the most common urease-negative bacteria established in the human urinary system, we isolated apparently urease-negative microorganisms from a consecutive series of 58 urinary stone-forming patients by using standard selecting agars. Pure strains were incubated in an inductive medium lacking all sources of nitrogen except urea. Induction of urease activity was monitored by a test based on the reaction of phenol/hypochlorite with ammonium ions. This test revealed whether the urease negativity of a strain indicated by the selective agar was optional or absolute. All strains we investigated by this method and which were classified by standard methods as urease-negative we found produced urease activity which was clearly measurable, though it was often comparatively small. In the light of these results, the matrix theory of calcium oxalate stone development will need some modifications.

Bacteria↗
PubMed1989

Long-term outcome of lithium prophylaxis in patients initially classified as complete responders.

The long-term outcome of lithium prophylaxis was explored in 43 bipolar and 36 unipolar patients who had been classified as complete responders after the first 2 years of treatment. These patients were followed up prospectively for a further period of 5 years (treatment period II), during which their psychopathological state was assessed monthly or bimonthly. Forty-nine patients completed treatment period II, 2 died during this period, 7 did not attend the unit any more and could not be traced, and 21 definitively interrupted lithium treatment before the end of the period. In 18 cases the decision to stop lithium was taken by the patient. Twenty-five patients relapsed during the treatment period II. Four relapsers had three or more episodes concentrated during the last 2 years of treatment. These results suggest that the predictive value of an initial favourable response to lithium should not be overrated, and that the impact of the drug on the long-term course of major affective disorders in ordinary clinical conditions might be less dramatic than currently believed.

Adult↗
PubMed1979

Metabolic heterogeneity of muscle fibers classified by myosin ATPase.

Muscle fibers are commonly classified histochemically into three types by the staining intensity for myosin ATPase combined with those for metabolic enzymes. Preincubation at pH 4.6 gives rise to three staining intensities of myosin ATPase which are also used for fiber typing. The two classification systems were compared by computer analysis of the individual staining profiles of over 2,500 fibers, and found not to be equivalent. The analysis showed metabolic heterogeneity among the fiber groups distinguished according to their differences in myosin ATPase.

Adenosine Triphosphatases↗
PubMed1976

Chronic tonsillar herniation: an attempt at classifying chronic hernitations at the foramen magnum.

A system is presented for the classification of chronic herniations of the cerebellar tonsils in the absence of space-occupying intracranial lesions, based on a survey of the literature and 13 own cases. The Arnold-Chiari malformation in adults typically involves herniation of the cerebellar tonsils instead of herniation of the vermis as is typical when it occurs in infancy. Identification of chronic tonsillar herniation with the Arnold-Chiari malformation in adults was thought to require at least one other sign of the Arnold-Chiari complex, e.g. a medullary deformity. Cases for which chronic herniation and sclerosis of the cerebellar tonsils present as the only nervous lesion are classified as "chronic tonsillar herniation". Such cases may manifest with neurological symptoms during adult life, or they may be found incidentally at autopsy. Attention is drawn to the occurrence of chronic tonsillar herniation in 7 infants and children where it apparently represents a cause of sudden unexpected death. The overlap between chronic tonsillar herniation and the Arnold-Chiari malformation of adults is discussed in regard to the frequence of associated osseous anomalies, hydrocephalus and syringomyelia.

Adolescent↗
PubMed1997

Syringomyelia and Arnold Chiari in scoliosis initially classified as idiopathic: experience with 25 patients.

The authors analysed the clinical and radiological findings and the surgical management of 25 patients admitted for scoliosis classified as idiopathic at first presentation, but in fact associated with spinal cord and/or brain stem anomalies. Twenty patients had syringomyelia, 19 had Chiari malformation. Scoliosis was the only presenting symptom when all these patients were referred to the orthopaedic surgeon. On examination, five patients had normal neurological findings, while the others showed very mild neurological deficits. The diagnosis of syringomyelia and Chiari malformation was established by MRI, which is the best form of neuroradiological examination for discovering spinal abnormalities. Neurosurgical treatment is strongly recommended as the first step in the management of "pseudo" idiopathic scoliosis.

Adult↗
PubMed2003

Classifying cases of fetal Wolff-Parkinson-White syndrome by estimating the accessory pathway from fetal magnetocardiograms.

The paper presents an evaluation of the possibility of using fetal magnetocardiogram (FMCG) signals to estimate and classify the accessory pathway in fetal Wolff-Parkinson-White (WPW) syndrome. The FMCG signals of two fetuses with WPW syndrome (type A) were detected using a 64-channel superconducting quantum-interference device system. An average across the cycles of these signals was taken to obtain clear WPW signals. To determine the direction and position of the accessory pathway in a fetal heart accurately, the accessory pathway and activated pathway at the peak of the QRS complex thus obtained were estimated for each fetus, using a single-dipole model. The phase angle (about 90 degrees) between the equivalent current dipoles (ECDs) was the same for both fetuses. This angle suggested that the accessory pathway is in the left side of the heart, i.e. that the pathway exists in the left ventricle, which indicates type A WPW syndrome. Identification of the position of the accessory pathway in a fetus with WPW syndrome from the angle between the ECD of the accessory pathway and the ECD of the peak in the QRS complex was thus demonstrated.

Electrocardiography↗
PubMedDate not supplied

A fuzzy pattern recognition method to classify esophageal motility records.

Analysis and classification of esophageal motility records were investigated using signal processing and fuzzy-set pattern recognition techniques. A set of parameters has been extracted from the raw records and has previously been used as characterizing features. Improvements to these procedures were obtained by extracting these features from processed data, and some additional parameters were developed. The new set of features was used in the design of a fuzzy classifier, and classification accuracy was estimated using the leave-one-out technique. To our knowledge, this is the first report of the application of automatic classification to esophageal motility records.

Data Collection↗
PubMed1992

Ventricular beat classifier using fractal number clustering.

A two-stage ventricular beat 'associative' classification procedure is described. The first stage separates typical beats from extrasystoles on the basis of area and polarity rules. At the second stage, the extrasystoles are classified in self-organised cluster formations of adjacent shape parameter values. This approach avoids the use of threshold values for discrimination between ectopic beats of different shapes, which could be critical in borderline cases. A pattern shape feature conventionally called a 'fractal number', in combination with a polarity attribute, was found to be a good criterion for waveform evaluation. An additional advantage of this pattern classification method is its good computational efficiency, which affords the opportunity to implement it in real-time systems.

Algorithms↗
PubMed1985

Appendiceal schistosomiasis. Method of classifying oviposition and inflammation.

Twenty surgical specimens of appendiceal schistosomiasis were reviewed retrospectively. They constituted 1 percent of 1984 appendices seen among approximately 15,000 surgical specimens examined at free central laboratories serving the Igbos of Nigeria, West Africa. Oviposition by Schistosoma haematobium was classified according to its association with suppurative appendicitis and normal appendices. Seven of ten infested appendices obtained at curative operations showed suppurative appendicitis, whereas eight of nine infested appendices removed at incidental appendectomies were negative. One interval appendectomy was also negative. It is postulated that utilization of this novel classification on a worldwide basis will help to end the controversy concerning the etiologic role of schistosome ova in acute appendicitis.

Adolescent↗
PubMed1995

Dynamic infusion cavernosometry and cavernosography in diagnosing and classifying venoocclusive dysfunction.

Dynamic infusion cavernosometry and cavernosography (DICC) were performed in 22 patients who were referred with symptoms of partial erection and transient erection and who were diagnosed as deep dorsal venous leakage by means of colour Doppler ultrasonography. We reached the diagnostic values for corporovenous leakage (CVL), also classified them and showed the veins that need to be ligated. With these advantages, DICC is a very cost-effective and safe technique that can be performed routinely in the diagnosis of corporovenous leakage.

Adult↗
PubMed1982

Srinivasan's coagulation test in taxonomically classified streptomycetes.

Srimivasan's coagulation test was performed in 18 strains of the genus Streptomyces and one strain of the genus Actinoplanes. The highest coagulation activity was detected in strains systematically classified in a series of streptomycetes with pink or red aerial mycelium: S. erythreus, Streptomyces sp. AJ/22, S. roseo-luteus and S. griseofuscus. With the exception of S. griscofuscus these three cultures also exhibited the highest inhibitory activity B. subtilis. When using hemoglobin as substrate it was possible to detect acid, neutral and alkaline proteinases with the highest poroteolytic activity at pH 3.0 to 4.0 in the most active strain of S. erythreus.

Actinomycetales↗
PubMed2000

Behavioral epidemiology: a systematic framework to classify phases of research on health promotion and disease prevention.

Although the term "behavioral epidemiology" has been used in the literature since the late 1970s, it has not been clearly defined. A behavioral epidemiology framework is proposed to specify a systematic sequence of studies on health-related behaviors, leading to evidence-based interventions directed at populations. The phase are: 1--establish links between behaviors and health; 2--develop measures of the behavior; 3--identify influences on the behavior; 4--evaluate interventions to change the behavior; 5--translate research into practice. Mature research areas are expected to have more studies in the latter phases. Recent volumes of four journals (Annals of Behavioral Medicine, Health Psychology, Journal of Nutrition Education, Tobacco Control) were audited, and empirical studies were classified into these phases. Phase 3 studies were common (identifying influences on behaviors; 27% to 50%), and Phase 2 studies were least common (measurement; 0% to 15%). Annals of Behavioral Medicine and Health Psychology were low on Phase 4 (intervention studies; 9% and 11%, respectively). The Journal of Nutrition Education was the only journal reviewed that had a substantial number (20%) of Phase 5 studies (translating research into practice). The behavioral epidemiology framework can be used to evaluate the status of research on health behaviors and to guide research policies.

Chronic Disease↗