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At least 235 records · Page 13Linked to original sources
PubMed2005

Diagnosing aortic valve stenosis by correlation analysis of wavelet filtered heart sounds.

Traditional auscultation performed by the general practitioner remains problematic and often gives significant results only in a late stage of heart valve disease. Valve stenoses and insufficiencies are nowadays diagnosed with accurate but expensive ultrasonic devices. This study aimed to develop a new heart sound analysis method for diagnosing aortic valve stenoses (AVS) based on a wavelet and correlation technique approach. Heart sounds recorded from 373 patients (107 AVS patients, 61 healthy controls (REF) and 205 patients with other valve diseases (OVD)) with an electronic stethoscope were wavelet filtered, and envelopes were calculated. Three correlations on the basis of these envelopes were performed: within the AVS group, between the groups AVS and REF and between the groups AVS and OVD, resulting in the mean correlation coefficients rAVS, rAVSv.REF and rAVSv.OVD. These results showed that rAVS (0.783 +/- 0.097) is significantly higher (p < 0.0001) than rAVSv.REF (0.590 +/- 0.056) and rAVSv.OVD (0.516 +/- 0.056), leading to a highly significant discrimination between the groups. The wavelet and correlation-based heart sound analysis system should be useful to general practitioners for low-cost, easy-to-use automatic diagnosis of aortic valve stenoses.

Adult↗
PubMed1992

The Rationality/Emotional Defensiveness Scale--II. Convergent and discriminant correlational analysis in males and females with and without cancer.

The psychological correlates of the Rationality/Emotional Defensiveness Scale and its two subscales were examined in 1236 males and 863 females from the Western Collaborative Group Study. An additional 157 males and 164 females with some form of cancer other than of the skin were also included in this analysis. Characteristics measured included self-reported emotional control, anger expression, trait personality, depressive and neurotic symptomatology, Type A behavior, hostility, and social desirability. Results indicate that the Rationality/Emotional Defensiveness Scale is most strongly related to the suppression and control of emotions, especially anger. Scores on this scale also tend to be associated with less Type A behavior and hostility and with more social conformity. Analysis of the component subscale suggests that Antiemotionality, i.e. the extent to which an individual uses reason and logic to avoid interpersonally related emotions, is most strongly marked by the control of anger, while Rationality, i.e. the extent to which an individual uses reason and logic as a general approach to coping with the environment, is related to the control of anxiety and a higher level of trait curiosity. The psychological interpretation of the scale appears to be largely invariant across gender, unaffected by residualization of the total scale score for its association with Social Desirability, and, except for a few minor instances, unrelated to the diagnosis of cancer.

Aged↗
PubMed1996

Temporal correlation analysis of penumbral dynamics in focal cerebral ischemia.

A novel temporal correlation technique was used to map the first-pass transit of iodinated contrast agents through the brain. Transit profiles after bolus injections were measured with dynamic computed tomography (CT) scanning (1 image/s over 50 s). A rabbit model of focal cerebral ischemia (n = 6) was used, and dynamic CT scans were performed at 30, 60, 90, and 120 min postocclusion. Within the ischemic core, no bolus transit was detectable, demonstrating that complete ischemia was present after arterial occlusion. In the periphery of the ischemic distribution, transit dynamics showed smaller peaks, broadened profiles, and overall delay in bolus transit. A cross-correlation method was used to generate maps of delays in ischemic transit profiles compared with normal transit profiles from the contralateral hemisphere. These maps showed that penumbral regions surrounding the ischemic core had significantly delayed bolus transit profiles. Enlargement of the ischemic core over time (from 30 to 120 min postocclusion) was primarily accomplished by the progressive deterioration of the penumbral regions. These results suggest that (a) temporal correlation methods can define regions of abnormal perfusion in focal cerebral ischemia, (b) peripheral regions of focal cerebral ischemia are characterized by delays in bolus transit profiles, and (c) these regions of bolus transit delay deteriorate over time and thus represent a hemodynamic penumbra.

Animals↗
PubMedDate not supplied

[Cross-correlation analysis of auditory neuron activity in response to acoustic clicks].

Cross correlation function relating the output spike train and the input puassoneous click trains were obtained for 213 single units located in the auditory midbrain center of the frog (Rana ridibunda). Five types of responses were found: type 1 (29 units) was due to polysynaptic unimodal excitation, type II (73 units) resulted from excitation followed by inhibition, type III (26 units) resulted from inhibition followed by excitation. In the IVth type (36 units) the excitation was preceded and followed by inhibition. The neurons of the Vth type had bimodal or trimodal correlation functions. The cross correlation functions allow to estimate the temporal shape of postsynaptic excitability changes and to reveal the inhibitory stimulus effects even for the units escaping spontaneous impulsation.

Animals↗
PubMed2002

Effect of hydrophobic surfactant proteins SP-B and SP-C on phospholipid monolayers. Protein structure studied using 2D IR and beta correlation analysis.

We have applied two-dimensional infrared (2D IR) and betanu correlation spectroscopy to in-situ IR spectroscopy of pulmonary surfactant proteins SP-B and SP-C in lipid-protein monolayers at the air-water interface. For both SP-B and SP-C, a statistical windowed autocorrelation method identified two separate surface pressure regions that contained maximum amide I intensity changes: 4-25 mN/m and 25-40 mN/m. For SP-C, 2D IR and betanu correlation analyses of these regions indicated that SP-C adopts a variety of secondary structure conformations, including alpha-helix, beta-sheet, and an intermolecular aggregation of extended beta-sheet structure. The main alpha-helix band split into two peaks at high surface pressures, indicative of two different helix conformations. At low surface pressures, all conformations of the SP-C molecule reacted identically to increasing surface pressure and reoriented in phase with each other. Above 25 mN/m, however, the increasing surface pressure selectively affected the coexisting protein conformations, leading to an independent reorientation of the protein conformations. The asynchronous 2D IR spectrum of SP-B showed the presence of two alpha-helix components, consistent with two separate populations of alpha-helix in SP-B-a hydrophobic fraction associated with the lipid chains and a hydrophilic fraction parallel to the membrane surface. The distribution of correlation intensity between the two alpha-helix cross peaks indicated that the more hydrophobic helix fraction predominates at low surface pressures whereas the more hydrophilic helix fraction predominates at high surface pressures. The different SP-B secondary structures reacted identically to increasing surface pressure, leading to a reorientation of all SP-B subunits in phase with one another.

Air↗
PubMed1983

A correlational analysis of symmetry between the arrowhead and featherhead Müller-Lyer illusions.

Correlational methods were used to investigate symmetry of effect for the arrowhead and featherhead versions of the Müller-Lyer figure. Two control figures were compared in the determination of baseline levels for measurement of the illusions: a shaft presented without any inducing context, and a shaft with vertical inducing lines attached. In addition, results based on difference-score measures of the illusions were contrasted with results obtained by partial-correlation techniques. Overall, when one considers the results for either one of the arrowhead or featherhead versions, the evidence favours a common underlying mechanism. However, results across the two versions suggest that the mechanisms for the two versions differ fundamentally. In weighting the different kinds of evidence contributing to this conclusion, methodological issues were raised. By obtaining two judgments for each stimulus figure from a large number of subjects, it was possible to demonstrate not only that conventional difference-score measures of illusions are highly unreliable, but also that they can yield biased results.

Adolescent↗
PubMedDate not supplied

[Cross-correlation analysis of spontaneous spike activity of neurons of the isolated cerebral cortex].

Correlation of neuronal impulse activity was studied in the visual and sensorimotor areas of the intact and chronically isolated rabbit cortex. Summate crosscorrelation function of neurones activity of the isolated cortex possess an a symmetrical bimodal form with positive significant deviations in both branches. Summate crosscorrelation function of cells activity in the intact cortex has a significant deviation only in the right branch. The possibility of transmission of excitation through the isolated and intact cortex is suggested and discussed.

Animals↗
PubMedDate not supplied

Correlative analysis of ethanol-related phenotypes in rat inbred strains.

As a summary presentation of the ethanol-related traits in the rat inbred strains, the responses to ethanol for various traits of the eight strains were analyzed. The intercorrelations among the means of the strains were computed and the interrelationships among the strain correlations were determined further by partial correlation and factor analysis. Sources of data on strain ethanol response included measures from laboratories of Drs. Deitrich, Li, Erickson, Pohorecky, and Tabakoff, who have participated in this joint study on the development of the rat heterogeneous stock (N/Nih). Although there are problems with estimating strain correlations from data collected in different laboratories, some informative associations among the ethanol-related traits were apparent. Genetic variation for behavioral and physiological responses to ethanol was indicated by the inbred strain distribution. The strains clearly differed in response to ethanol, with the mean of the National Institutes of Health stock falling intermediate within the range of the inbred strain distribution. For the ethanol-related traits considered jointly, an association between initial behavioral sensitivity, ethanol intake, and metabolism, as well as an association between development of tolerance, initial sensitivity, and several physiological measures, was suggested. Thus, the rat heterogeneous stock, a systematically outbred population, should provide a useful animal model with which to study the physiological basis for ethanol intake and preference, response to acute ethanol, and the development of tolerance.

Alcohol Drinking↗
PubMed2004

2DCOR-GC: an application of the generalized two-dimensional correlation analysis as a route to optimization of continuous flow supercritical fluid reactions.

A new approach for optimization and monitoring of continuous reactions has been developed using 2D correlation methods for the analysis of GC data (2DCOR-GC). 2DCOR-GC maps are obtained following perturbation of the system that allow the effect of changing reaction parameters such as time, temperature, pressure, or concentration to be both monitored and sequenced with regard to changes in the raw GC data. In this paper, we describe the application of the 2DCOR-GC technique to monitoring the reverse water-gas shift reaction in scCO(2). 2DCOR-GC is combined with FT-IR data to validate the methodology. We also report the application of 2DCOR-GC to probe the mechanism of the alkylation of m-cresol with isopropyl alcohol in scCO(2) using Nafion SAC-13 as the catalyst. These results identify coeluting peaks that could easily be missed without exhaustive method development.

Journal Article↗
PubMed2004

Haplotype sharing correlation analysis using family data: a comparison with family-based association test in the presence of allelic heterogeneity.

The haplotype-sharing correlation (HSC) method for association analysis using family data is revisited by introducing a permutation procedure for estimating region-wise significance at each marker on a study segment. In simulation studies, the HSC method has a correct type 1 error rate in both unstructured and structured populations. The HSC signals on disease segments occur in the vicinity of a true disease locus on a restricted region without recombination hotspots. However, the peak signal may not pinpoint the true disease location in a small region with dense markers. The HSC method is shown to have higher power than single- and multilocus family-based association test (FBAT) methods when the true disease locus is unobserved among the study markers, and especially under conditions of weak linkage disequilibrium and multiple ancestral disease alleles. These simulation results suggest that the HSC method has the capacity to identify true disease-associated segments under allelic heterogeneity that go undetected by the FBAT method that compares allelic or haplotypic frequencies.

Alleles↗
PubMedDate not supplied

A method for correlations analysis of coordinates: applications for molecular conformations.

We describe a new method to analyze multiple correlations between subsets of coordinates that represent a sample. The correlation is established only between specific regions of interest at the coordinates. First, the region(s) of interest are selected at each molecular coordinate. Next, a correlation matrix is constructed for the selected regions. The matrix is subject to further analysis, illuminating the multidimensional structural characteristics that exist in the conformational space. The method's abilities are demonstrated in several examples: it is used to analyze the conformational space of complex molecules, it is successfully applied to compare related conformational spaces, and it is used to analyze a diverse set of protein folding trajectories.

Amino Acid Sequence↗
PubMed1976

Correlation analysis of muscle spindle responses to single motor unit contractions.

1. Cross-correlation techniques have been used to study the responses of muscle spindle afferents from the soleus muscle of the cat to twitch contractions of single motor units. 2. Cross-correlograms (post-stimulus time histograms) were used to give the frequency of occurrence of a receptor spike at various times following the initiation of a motor unit contraction together with a display of the average twitch tension wave form. 3. The cross-correlograms revealed that the contraction of a single motor unit can be an effective stimulus to a spindle receptor and may induce afferent firing pattern alterations similar to those observed with whole muscle contraction. 4. The cross-correlograms also revealed quantitative differences in the response of a receptor to contraction of different motor units and to contraction of the same motor unit at different lengths. These differences reflect subtle changes in receptor deformation developed by the twitch of a motor unit under different conditions and by the twitches of different motor units. The results are consistent with anatomical data on the number and distribution of motor units and receptor organs in cat soleus. 5. These findings emphasize that rather than simply acting as generalized force or length sensors for the muscle as a whole, each receptor's spike train carries information about the state of a particular set of motor units.

Afferent Pathways↗
PubMed1980

[Correlation analysis of the conjugation tables].

The paper describes a method for determining the correlation of the frequency indices grouped in the conjugation tables. The main stages involve the calculation of Pirson's criterion, determination of confidential probability of the correlation coefficient by comparison of the calculated Pirson's criterion with the standard values, and calculation of the correlation coefficient. The latter may vary within 0-1 and characterizes the correlation strength.

Acute Disease↗
PubMed1981

A two-stage immunocytochemical method for oestrogen receptor analysis: correlation with morphological parameters of breast carcinomas.

An immunocytochemical method for oestrogen receptor (ER) analysis of breast carcinomas is described and compared with the dextran-coated charcoal (DCC) assay and a cytochemical method. The method described is superior to the purely cytochemical, especially in terms of sensitivity, demonstration of nuclear receptors and correlation with the DCC assay. The DCC assay is reliable except in the case of poorly cellular tumours: in these the immunocytochemical method is far superior, being independent of tumor cellularity. With this new method, lobular carcinomas are shown to be ER-rich compared with their ductal counterparts, a conclusion currently disputed, largely because methods employed mostly fail to take account of tumour cellularity. A combination of the DCC assay and the immunocytochemical method here described gives the maximum information about the ER-status of a particular carcinoma.

Adult↗
PubMed1995

Rigid-body motions of sub-units in DNA: a correlation analysis of a 200 ps molecular dynamics simulation.

A 200 ps molecular dynamics simulation of the B-form double stranded self-complementary octanucleotide d(CTGATCAG) is analyzed in terms of correlated motions using the canonical analysis approach. Each nucleotide is decomposed in three sub-units corresponding to the base, the sugar ring and the backbone respectively. The correlation between the full dynamics of two sub-units was found to decrease as their mutual distance increases. The interpretation of the full dynamics of sub-units as the superimposition of rigid-body motions (translation and orientation) and deformation shows that the main source of correlation is rigid-body motions. Correlation between sub-units deformation is weak and practically vanishes for sub-units belonging to non-adjacent nucleotides. It is also shown that the correlation is much more important for sub-units of the same strand than of opposite strands. We conclude that the internal dynamics of the octanucleotide may be well described by rigid-body motions, the sub-units deformation having only local influence whereas sub-units translation and rotation have repercussion to long distances. The results presented in this study suggest how the number of degrees of freedom may be reduced for simulating long-time dynamics of oligonucleotides.

Computer Simulation↗
PubMed1978

Correlation analysis of the physiological factors controlling fundamental voice frequency.

A technique has been developed to obtain a quantitative measure of correlation between electromyographic (EMG) activity of various laryngeal muscles, subglottal air pressure, and the fundamental frequency of vibration of the vocal folds (Fo). Data were collected and analyzed on one subject, a native speaker of American English. The results show that an analysis of this type can provide a useful measure of correlation between the physiological and acoustical events in speech and, furthermore, can yield detailed insights into the organization and nature of the speech production process. In particular, based on these results, a model is suggested of Fo control involving laryngeal state functions that seems to agree with present knowledge of laryngeal control and experimental evidence.

Acoustics↗
PubMed2000

[Correlation analysis of laryngeal vocal efficiency and nasalance after vertical hemilaryngectomy].

OBJECTIVE: To analyse the correlation between laryngeal vocal efficiency and nasalance for patients after vertical hemilaryngectomy. METHOD: The lately invented instruments, phono-laryngography and nasometer, which can objectively evaluate vocal function, were used to determine the laryngeal vocal efficiency and nasalance in 30 patients with laryngeal carcinoma treated primarily by vertical hemilaryngectomy. RESULT: The results showed that laryngeal vocal efficiency and nasalance have significant positive correlations in all subjects (r = 0.47). CONCLUSION: Change of laryngeal vocal function influence the value of nasalance.

Adult↗