SEARCH · Search PubMed

Results for “Feature selection”

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.

SourceResearch connectionFrom yearThrough year

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

At least 811 records · Page 45Linked to original sources

PubMed1990

Signal analysis for ECG interpretation.

In ECG interpretation usually two main areas are discerned: the signal analysis and the diagnostic classification. This article reviews the major developments in the first area. ECG signal analysis itself is subdivided into the stages data acquisition, data transformation, feature selection, and data reduction. These stages are consecutively reviewed, while in the data transformation stage digital filtering, detection, wave typing, beat selection, and boundary recognition are discussed.

Algorithms↗

PubMed1990

Predictive value of intraoperative liver biopsies of donor organs in patients undergoing orthotopic liver transplantation.

The evaluation of prerevascularization and postrevascularization biopsies in comparison with clinical and laboratory data has revealed a direct correlation between elevated PT and AST levels and pericentral and panlobular individual hepatocyte necrosis. No other significant correlations were determined when comparing selected histologic features to selected clinical laboratory values. In conclusion, these biopsies are of limited use in predicting subsequent allograft function in the absence of prominent individual hepatocyte or pericentral necrosis.

Adult↗

PubMed1990

[The use of the method of principal components for phenogenetic analysis of the integral domestication trait].

In the course of long-term experiment on domestication of silver fox, it was necessary to determine the most important behavioral features, selection for which would give domestication effect. The mathematical method of principal components was used for the analysis of 20 fox behavior traits. The combination of the initial traits which reflected the structure of the integral trait, i.e. domesticated type of behavior, was determined. The practical use of this combination seems to more adequately estimate the level of domestication of a given animal, which is indispensable for subsequent effective selection.

Animals↗

PubMed1989

Fully automated measurements by light microscopy of tissue sections using a cellular array computer.

Software was developed for the acquisition, segmentation and analysis of microscopic OD-images on a VICOM digital image processor, extended with a VISIOMORPH morphoprocessor board. The delineation algorithms for peroxisomes, lysosomes, and nuclei in liver, kidney, and adrenal gland sections start by thresholding the difference between the original image and a low pass filtered version. The resulting binary mask is then processed by morphological operations in order to produce an object overlay. The efficiency of the programs is evaluated by comparing delineated objects at different OD-levels, created by varying the stain or by multiplying the original pixel values with constant factors. Manual delineation on some images is also used as a reference. More complex algorithms are used for the delineation of muscle fibres in ATP-ase-stained sections and immunocytochemically labelled cells in monolayer preparations. Muscle images from parallel sections with different stainings are matched with a coordinate transform, enabling the transfer of the object mask from a single delineated image to the unprocessed images and thus obtain all necessary information for fibre classification. After segmentation, the OD-images and their object overlays are fed into a data extraction program, measuring for each delineated object user-selected features. Data are sent to a VAX for statistical interpretation.

Adrenal Cortex↗

PubMed1989

Karyometric marker features in tissue adjacent to invasive cervical carcinomas.

A companion study showed the existence of statistically significant changes in the value of karyometric "marker features" in the nuclei of histologically normal-appearing ectocervical epithelium adjacent to carcinomas in situ. In this second part of the study, the results obtained in patients with invasive cervical carcinomas were analyzed. Formalin-fixed, paraffin-embedded tissue sections were Feulgen stained and analyzed with a microTICAS video microphotometer. The results, demonstrated for the first time in histologic material, indicate that the marker features are clearly expressed in a majority of nuclei observed in the normal-appearing tissue adjacent to invasive lesions. This effect was statistically significant. The best marker features selected by the discriminant analysis were nuclear roundness, nuclear perimeter length, total optical density and a run length texture measure. These findings may reflect a subtle transformation of the apparently normal cervical epithelium adjacent to an invasive cervical carcinoma.

Carcinoma↗

PubMed1987

Discounting an adverse maternal effect on severity of neurofibromatosis.

Neurofibromatosis, a common, progressive, autosomal dominant disorder, is markedly variable in its expressivity. Some authors have suggested that some contribution to neurofibromatosis's variability may be an adverse effect of a mother's neurofibromatosis on the overall severity seen in her offspring with neurofibromatosis. In the present study of 188 maternal affected, paternal affected, and sporadic von Recklinghausen neurofibromatosis cases, the maternal influence question was systematically examined. Overall severity, selected features most likely to reflect in utero maternal influence, and other common neurofibromatosis-I features were analyzed statistically. Age, racial composition, and gender of the three groups were similar. No significant differences were found (P less than or equal to .01) between maternal affected, paternal affected, and sporadic cases in terms of overall severity, probability of reaching advanced severity as a function of age, indications of possible prenatal influence (eg, congenital neurofibromas, tibial pseudarthrosis), or other neurofibromatosis features. These results demonstrate that the nature and severity of neurofibromatosis for maternal affected cases are essentially the same as for paternal affected and sporadic cases.

Adolescent↗

PubMedDate not supplied

[Dynamics of the age structure of residents in homes for the aged and nursing homes].

In state-run residential and nursing homes in the GDR the proportion of those residents of at least 80 years of age increased from 41.5 to 56.0 p.c. between 1980 and 1983, diversified on districts they moved between 70.0 and 46.5 p.c. Some selected features were correlated, only a low degree of dependence being found on the age-structure of the district-population (r = +0.26), highest degree on the ratio home-capacity/district-population (r = -0.65).

Aged↗

PubMed1982

Occupational mortality and morbidity in relation to selective turnover.

Because of the "healthy worker effect" most occupational cohorts, especially those of persons doing physically heavy work, are selected groups with regard to life expectancy. Health selection is also involved in turnover. Mortality and morbidity were studied on three different exposure levels, defined primarily according to physical demands: heavy level (iron foundries), medium level (manufacture of metal products), and light level (manufacture of electrical devices). The population comprised about 15,700 men who were employed in 1950-1976 in the three branches of the metal industry representing the different levels. The number of person-years of follow-up became about 215,800. During the period 1950-1978, there had occurred 1,407 deaths. Data for the mortality and disability analyses were obtained from the national death and disability registers. Occupational history, morbidity, and reasons for turnover were studied in a sample by means of questionnaire sent to 400 current and 600 former workers from each branch. In addition, a questionnaire concerning occupational history was sent to the next of kin of 450 dead persons. When the three cohorts were compared to the general male population of Finland, the standardized mortality ratio was 124 for the foundry workers, 92 for the metal product workers, and 107 for the electrical workers. The survival curves showed no great differences between the three exposure levels. However, the heavy level had the highest degree of mortality, and the medium level the lowest. Foundry workers showed less social selection than the two other cohorts. Metal product workers seemed to be socially and health selected. Economic fluctuations clearly regulated entries of new employees into the industries and thus introduced additional selective features.

Adolescent↗

PubMed1981

Leukemia revisited.

Selected features of the historical development of our knowledge of leukemia are discussed. The use of different methodologies for study of the nature of leukemic cell proliferation are analyzed. The differences between older cell kinetic data using tritiated thymidine and autoradiography and the newer cell culture methods are more apparent than real. It is suggested that tritiated thymidine and extracorporeal irradiation of the blood may be useful for therapeutic agents that have not been given an adequate trial. Radiation leukemogenesis presents an opportunity for study of the nature of leukemogenesis that has not been exploited adequately.

Animals↗

PubMed1981

[Metric examinations on the development of apical dendrites of cortical pyramidal cells during the postnatal time in the rat].

1. It is explained the postnatal evolution of some selected features of Golgi-impregnated layer V pyramidal neurons in the rat sensorimotor cortex from the 1st to the 90th day after birth (13 stages) quantitatively. Especially it is reported about the development of the length and the quantity of apical main dendrites and of the apical lateral branches from the 1st to the 3rd order as well as the branching behaviour of the dendrites (free ends of dendrites, branching points, ramification index). 2. The evolution of mean length of apical dendrites is represented by a sigmoidal polygon trace - like the classic growing curve. 3. During the 3rd month of the postnatal life the lateral branches of the apical dendrites show a distinct growing increase relating to the mean values of the total length of dendrites, their quantity and the branching behaviour. This intensification of growth is in contrast to the growing stagnation of the apical main dendrites in this time. 4. From this point of view it is deduced that relating to the maturation of pyramidal cells - contrary to the papers of other writers and contrary to a previous private conception - albino rats in the age of 3 months do not are differentiated cortical completely. 5. The several marks of pyramidal dendrites do not form themselves in the same time but successively. The maturing process of new dendrites or dendrite branches is the base of significant increase of the length. 6. It seems, that the formation of dendritic "tree" takes place in growing batches. In this context there are discussed the correlations between the morphometric conceivable changes in the cortical pyramids and the accession of functions in the animal.

Animals↗

PubMed1980

Aytpia status index of respiratory cells: a measurement for the detection and monitoring of neoplastic changes in squamous cell carcinogenesis.

A statistical procedure was developed for calculating an atypia status index (ASI) for cells from the bronchial mucosa. These indices represent the degree of abnormal changes in these cells and classify them as squamous metaplasia, mild atypia, moderate atypia, servere atypia or carcinoma. The classification accuracy of the procedure was more than 99% on trained data and was accomplished by minimizing the overlapping areas between the adjacent multivariate distributions of cell groups for selected features whose group means represent a monotonic function and for which the cell categories are distinguishable. The calculated ASI may reflect abnormal changes in the cell that may not be clearly evident visually. It appears that progression or reversal of bronchial epithelial atypia can be accurately monitored by studying the changes in the ASI, not only for preneoplasia but also for reactions to chemotherapy and various pulmonary infectious disease processes, such as influenza.

Adult↗

PubMed1995

Issues and challenges in the design of curriculum information systems.

Medical schools are increasingly using curriculum information systems to better manage their curricula, to incorporate alternative learning environments, to expand subject-specific instruction, or to adapt the curricula to the changing health care environment. A curriculum information system contains key features, selected by the system's designers, that describe the objectives, the specific content, and/or the educational activities that compose the curriculum. The underlying purpose of such a system is to document and describe the knowledge, behaviors, skills, attitudes, or activities students will be expected to develop or learn. While it might be ideal to have one system that would meet the needs of all possible users, the programming and maintenance requirements of such a single system would exceed most medical schools' resources. Thus, designers of curriculum information systems must first identify the primary intended-user group: students, faculty, or administrators. The system designed for one group will typically differ from the systems for other groups in the emphasis on and level of content detail and curriculum structure information. The general structure and purposes of curriculum information systems are expressed in three distinct system designs: a curriculum database (most helpful for administrators), a curriculum textbase (for faculty), and an electronic syllabus (for students). The authors describe these different designs, and they discuss challenges faced by system designers.

Curriculum↗

PubMed1997

Computerized analysis of daily life motor activity for ambulatory monitoring.

The primary goal of an ambulatory monitoring of motor activities (AMMA) system is to document the occurrence of random and spontaneous motor activities (e.g., sitting, lying, standing, walking, running, etc.) of the ambulatory subject in natural environmental circumstances. Much progress has been made in recording fidelity, reduction in energy requirement, fixation of the accelerometers, equipment size and weight, memory capacity and data acquisition. At present, our laboratory is interested in developing an automated off-line AMMA-signal analysis system. The system has to take care of activity (wave) detection, recognition of onsets and endpoints of the various activities (waves), and computation of a set of relevant clinical parameters (e.g., total walking time, number of times rising from a chair, etc.) from long-term recorded data. Two methods are currently being used for computerizing the off-line analysis system: using an artificial neural network and using a set of selected features extracted from the input data. The present paper is aimed at the latter method. The method was successfully applied to long-term recorded data sets of eight male amputees and three other subjects. The primary results indicate that the method is a potentially useful too to computerize the off-line analysis system.

Activities of Daily Living↗

PubMed1997

[Macroscopic evaluation of placenta from ecologically-challenged area (Plock) -- Part I].

It was analysed selected features macroscopic of 226 placentas from normal pregnancies. The 146 was obtained from phenol's polluted area (Płock) and 80 from control group. It was proved statistical significant difference in distance of membrane rupture from placentas edge and in quality of amniotic epithelium. The appearance of this changes demonstrates (proves) for disadvantageous phenol's influence on the placenta.

Amniotic Fluid↗

PubMed1996

[Application of adaptive resonance theory network to the quality evaluation of radix Sophorae flavescentis].

ART1 and ART2 models of adaptive resonance theory network have been employed in quality evaluation of 40 Radix Sophorae Flavescentis samples collected from different regions of China. Based on the UV data of MeOH extract and IR data of CHCL3 extract, Shannon information theory has been used for feature selection. The results consist with those of traditional appraisal.

Drugs, Chinese Herbal↗

PubMed1998

Automatic classifiers for the interpretation of electrocardiograms.

The morphological diagnosis of ECGs is a pattern recognition procedure. The way the clinician does this is not clearly elucidated. Nevertheless, several models aimed at achieving identical results by automatic means are empleyed. While in the doctor's case this is not exactly so, the computer task for ECG interpretation comprises two distinct and sequential phases: feature extraction and classification. A set of signal measurements containing information for the characterization of the waveform is first obtained. These waveform descriptors are then used to allocate the ECG to one or more diagnostic classes in the classification phase. The classifier can embody rules-of-thumb used by the clinician to decide between conflicting ECG diagnosis and formal or fuzzy logic as a reasoning tool (heuristic classifiers). On the other hand, it can use complex and even abstract signal features as waveform descriptors and different discriminant function models for class allocation (statistical classifiers). More recently, artificial neural network techniques have also been used for signal classification. The authors review feature selection techniques and classification strategies, problems and methods of performance evaluation and results obtained by different classification approaches. A brief discussion of the relative merits of the two main types of ECG classifiers, logical and statistical, is included.

Diagnosis, Computer-Assisted↗

PubMed1998

Sex and the human female reproductive tract--what really happens during and after coitus.

The scientific study of the interaction of human genitals during coitus and after ejaculation with and without female orgasm has always been difficult and controversial with ethical, technical and social problems. The present brief review examines critically the results from these studies. Early observations utilised changes induced in sexually self-aroused subjects or by coitus with artificial (transparent) penes with few objective measurements. These culminated in the synthesis of the useful unitary descriptive, EPOR (excitation, plateau, orgasm, resolution)-model by Masters and Johnson (1966). Later investigations by other workers developed or employed instrumentation to record objectively the changes induced in the motility and pressures of genital muscles, in genital blood flow, in the ion and fluid movements creating the neurogenic transudate of vaginal lubrication, in its pH and pO2 and in the disposition of the ordered spurting ejaculate with subsequent sperm transport. More recently, studies have begun to use endoscopy and ultrasound imaging to picture what really happens especially during penile thrusting. While the newer techniques have often confirmed selected features of the original EPOR model they have also shown that the characterisation of the coital changes just by a unitary model is inappropriate. New observations suggest a plurality in the changes that can occur. Coital mechanisms are dynamic and our investigations and descriptions of them should match their dynamism. The knowledge gained will be more than helpful in the treatment of infertility, genital dysfunctions and disease transmission.

Cervix Uteri↗

PubMed2000

Effects on discrimination performance of selective attention to tactile features.

This study examined selective attention to tactile dimensions by combining a selective cueing paradigm with a test of integrality. In Experiment 1, subjects selectively attended to changes in the frequency or duration of pairs of vibrotactile stimuli and identified the higher frequency or longer duration stimulus. In Experiment 2, using surface gratings in an identical experimental procedure, subjects identified the rougher or longer duration stimulus. In both experiments, greater performance accuracy was found on trials where the cue correctly (valid) predicted the changing dimension, vs incorrectly (invalid) cued or no-cue (neutral) trials. More errors on the invalidly vs neutrally cued trials show the cost of focal attention. Increases in performance on validly vs neutrally cued trials show a benefit of filtering irrelevant stimuli in the cued conditions. Results effectively demonstrate focal attention to tactile features. Tests of integrality, in terms of the effects of correlated change in both dimensions, showed no redundancy gain for either vibrotactile or grating tasks, suggesting that frequency and roughness are separable from stimulus duration. Interference of negative correlated change for frequency but not roughness discriminations may be explained by differences in task difficulty.

Adult↗