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Results for “Correlation analysis”

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At least 325 records · Page 18Linked to original sources

PubMed1993

Correlation analysis between bovine populations, other farm animals, house pets, and multiple sclerosis prevalence.

In a previous study we analyzed the possible relationship between dairy product consumption and multiple sclerosis (MS) worldwide. We showed that a good correlation (Spearman rank p = 0.836), statistically strongly significant (p < 0.0001), existed between liquid cow milk consumption and MS prevalence. The interpretation of this strong correlation between MS and milk consumption is still unclear: fresh milk could be considered as a cofactor, but it could also reflect a much stronger association with MS of another unstudied factor, well correlated with milk consumption (yet, this is not the case for latitude). Obviously, the bovine population in each country and, particularly milk cows, has to be considered. In the present study, we analyze the correlations existing between the figures of national cow milk production and MS prevalence in 20 countries. We also analyze the correlations with the whole bovine, ovine, caprine, porcine, horse, poultry, cat and dog populations. Here again we find significant correlations between (i) cow milk production per inhabitant, (ii) national bovine density per inhabitant, and (iii) local bovine geographic density, and MS prevalence. However, these correlations are relatively weaker than that found with fresh liquid milk consumption in our previous study. No correlation is found with other farm animals or with pets in the same countries. The epidemiological significance of these results, suggesting a preponderant role of fresh cow milk, is discussed.

Animals↗

PubMed1990

Correlation analysis of gap junction lattice images.

Fourier averages of connexon images computed from low-irradiation electron micrographs of isolated negatively stained gap junction domains exhibited differences in stain distribution and connexon orientation. To analyze these polymorphic structures, correlation averaging methods were applied to images from negatively stained and frozen-hydrated specimens. For the negatively stained specimens, separate averages over two subsets of connexons with differing degrees of stain accumulation in the axial channel were obtained. Two populations of connexons with opposite skew orientations were distinguishable within a single junctional domain of a frozen-hydrated specimen. Correlation maps calculated using the left- and right-skewed references showed that the selected connexons tend to locally cluster. Using correlation methods to analyze packing disorder in a typical connexon lattice, we estimated the root-mean-square variation in the nearest neighbor pair separation to be approximately 11% of the lattice constant. Displacements of the connexons relative to each other increased with increasing pair separation in the lattice, rather like a liquid, although long-range orientation order was conserved as in a crystal. These results support the hypothesis that the hexagonal ordering of the connexons results from short-range repulsive forces.

Biophysical Phenomena↗

PubMed2006

Skin cholesterol: test performance, evaluation of potential determinants and correlation analysis with cardiovascular risk factors and circulating markers of inflammation.

BACKGROUND: Skin cholesterol (SkC) has been suggested to be an additional risk predictor, so we evaluated the test performance, potential determinants of this marker as well as a potential correlation of SkC with markers of inflammation and the history of cardiovascular events. PATIENTS AND METHODS: SkC, determined by the non-invasive PREVU POC Skin Sterol test, as well as serum lipids, the body fat status, high-sensitive CRP (hs-CRP) and serum amyloid A (SAA) were evaluated in consecutive patients with and without documented atherosclerotic disease. RESULTS: SkC was assessed in 201 patients. The within-day precision (CV) was 3.8%, the day-to-day CV of the right hand was 8.6% and 4.3% for the left hand, respectively. Neither univariate analysis nor multiple regressions identified a significant influence of age, sex, serum lipids, body fat status, smoking or diabetes mellitus on SkC, corresponding results were observed in a further analysis including 174 of these patients concerning hs-CRP and SAA (all p > 0.05). T-test analyses detected no significant differences between patients with and without a history of coronary, peripheral vascular and cerebrovascular events (all p > 0.05). CONCLUSIONS: The PREVU POC Skin Sterol test for the assessment of SkC proved an acceptable test performance. SkC is independent from serum lipids, traditional cardiovascular risk factors, two sensitive markers of systemic inflammation as well as the history of cardiovascular events indicating that the perception of this parameter as an established marker of vascular disease is premature.

Aged↗

PubMed1996

Quantitative hybridization kinetics of DNA probes to RNA in solution followed by diffusional fluorescence correlation analysis.

Binding kinetics in solution of six N,N,N',N'-tetramethyl-5-carboxyrhodamine-labeled oligodeoxyribonucleotide probes to a 101mer target RNA comprising the primer binding site for HIV-1 reverse transcriptase were characterized using fluorescence correlation spectroscopy (FCS). FCS allows a sensitive, non-radioactive real time observation of hybridization of probes to the RNA target in the buffer of choice without separation of free and bound probe. The binding process could directly be monitored by the change in translational diffusion time of the 17mer to 37mer DNA probe upon specific hybridization with the larger RNA target. The characteristic diffusion time through a laser-illuminated open volume element with 0.5 micron in diameter increased from 0.13-0.2 ms (free) to 0.37-0.50 ms (bound), depending on the probe. Hybridization was approximated by biphasic irreversible second-order reaction kinetics, yielding first-phase association rate constants between 3 x 10(4) and 1.5 x 10(6) M-1 s-1 for the different probes. These varying initial rates reflected the secondary structures of probes and target sites, being consistent with a hypothetical binding pathway starting from loop-loop interactions in a kissing complex, and completion of hybridization requiring an additional interaction involving single-stranded regions of both probe and target. FCS thus permits rapid screening for suitable antisense nucleic acids directed against an important target like HIV-1 RNA with low consumption of probes and target.

Animals↗

PubMed1992

Correlation analysis of somatosensory evoked potential waveforms.

Somatosensory evoked potential (SEP) waveforms were recorded over the spine and scalp in response to tibial nerve stimulation at the ankle for 28 subjects. The scalp data were analyzed with the correlation coefficient (CC) to determine the reproducibility of the signals and to identify side-to-side symmetry. The test for reproducibility uses the CC to verify validity, a low CC implying that the data are defective. The symmetry test uses the CC to obtain a measure of similarity of the responses to stimulation from opposite sides of the body. Statistics are presented showing the normal ranges of the CC values and their standard deviations. We conclude that the CC can provide objective and quantitative waveform information that complements latency and amplitude measurements in the clinical interpretation of tibial SEP waveforms.

Databases, Factual↗

PubMed1984

Portal venous thrombosis: correlative analysis of sonography, CT and angiography.

In 17 patients with portal venous thrombosis; nine due to venous invasion by liver tumors, and eight due to benign causes, sonograms and CT scans were reviewed, and the results were correlated with angiography. Sonography detected portal venous thrombosis in 94% and CT in 76%. Sonography was better than CT in the demonstration of the extent of thrombosis. By the detection of solid masses in the liver, and contiguous thrombosis of the segmental portal veins, both sonography and CT were accurate in the differentiation of venous invasion by tumor from benign thrombosis. Angiography was 91% accurate and was unique in the demonstration of arterioportal shunting and detailed vascular anatomy of the portal venous system.

Angiography↗

PubMed1981

[Correlation of the quantitative ECG and echocardiogram indices in left ventricular hypertrophy according to correlational analysis data].

In 47 patients with arterial hypertension and clinicoroentgenological signs of hypertrophy of the left ventricle the echo- and electrocardiographic study (the McFee-Parungao system) was carried out. Highly significant (p less than 0.001) direct correlation was revealed between the index of the corrected ECG, such as sigma R x,y,z + + sigma S x,y,z and Rx + Sz with echocardiographic indices of mass r = +0.851 and +0.848, respectively, and the thickness of the left ventricle of the myocardium (r = +0.806 and +0.794, respectively). The above electrocardiographic indices do not correlate to the main echocardiographic indices of the contractile function of the left ventricle.

Cardiomegaly↗

PubMed1982

Cross-correlation analysis of midbrain reticular neuron pairs during sleep-waking cycle of the cat.

By simultaneously inserting three extracellular microelectrodes, separated by 1.0 mm from each other, into the cat's midbrain reticular formation (MRF), temporal cross-correlation of firing of neuron pairs was measured to investigate the mode of interaction among the MRF neurons during different states of sleep and wakefulness. None of 97 neurons pairs studied gave clear-cut cross-correlograms suggesting cascade connection between two neurons. However, 29 neuron pairs showed weakly synchronized firing which occurred periodically with a mean interval of 1.23 s. This interval was different from the respiratory cycle. The rhythmic synchronization appeared most obviously during slow wave sleep. The synchronized firing was encountered more often in the pairs of adjacent neurons picked up with a single electrode and in the pairs picked up with separate electrodes positioned along the mediolateral axis, when compared with the neuron pairs located along the rostrocaudal axis. About 80% of the neurons (37 our of 46) which showed periodically synchronized discharge had no corresponding periodicity in their auto-correlograms. Simple synaptic linkage conceivable for the observed periodic synchronization of a neuron pair would be shared inhibition with the common inhibitory source activated periodically. Some neurons in the dorsal raphe nucleus and in the solitary tract nucleus were also examined for the cross-correlation with the MRF neurons. However, no positive relationship was found.

Animals↗

PubMedDate not supplied

[Correlation analysis of predictive factors of successful implantation in fertilization in vitro].

INTRODUCTION: Endometrial receptivity as isolated predictive factor of successful implantation, with its specifity is determined with numbered factors. PURPOSE: Purpose of this study was to evaluate significance and correlation between relevant factors using appropriate statistical analyses on term of embryo implantation. MATERIAL AND METHODS: Evaluated group contained 85 women whom according different causes of infertility have been determined for assisted reproduction program. Analysed measurements were: endometrial thickness, assessed hyperechogenity in relation with absolute endometrial thickness (HEA relation) and uterine blood flow (pulsatile index-Pi). Simultaneously were analyzed serum estradiol (E2; pg/ml) and progesterone (P; nmol/l) levels. After these evaluations achieved results were processed with standard statistical pack. Beside that were applied parameter and nonparameter tests with aim to test significancy of difference and multiple regressive analyse (Stepwise). RESULTS: Resulted measured parameters have been presented in basic analyse as middle value (Xrs) from all measurements + SD (standard deviation) and significance of difference is tested by mentioned statistical tests (Table 1). Application of Stepwise analyse, "step by step", has used parameter by parameter based on value which has decreased variability and based on achieved correlative coefficient between dependent uneven and complex of independent uneven values. This procedure confirms best correlation between HEA relation and serum progesterone levels and HEA relation in correlation with associated values: P, E2 and endometrial thickness (Table 1). DISCUSSION: Investigation provided till now shows that embryo quality and endometrial receptivity with highest probability determine success of applied assisted reproduction, successful embryonal implantation There is assessed influence of endometrial receptivity represented trough HEA relation using many folded regressive analyse where qualitative endometrial value has been looked with dependency with other parameters gives picture for high determinancy with hormonal activity and with stimulative ovarian activity. This determinancy could be viewed mostly through serum progesterone levels on day of HCG administration. Correlative relation between qualitative endometrial characteristics on day of HCG administration has high value related to progesterone levels. CONCLUSION: Results presented with this research confirm once again complexity characteristic for factors that play final role in embryo implantation in IVF program. There is presented only one aspect related with this problem with aim to contribute quantification importance and assessment rate of mutual influence these factors known till now as relevant.

Blood Flow Velocity↗

PubMed1997

[A cross-correlational analysis of the bioelectrical activity of muscle antagonists in studying human voluntary motor activity in certain forms of motor disorders].

In healthy [correction of beglth] subjects, patients with children's cerebral palsy and spinal cord disturbances, the cross-correlation function of the EMG at the initial phase of voluntary movement and at the phase of static voluntary tension revealed some mechanisms maintaining coordinated interrelations among antagonist muscles at different phases. A new approach is suggested for estimation of the electromyogram and for a finer diagnosis of the CNS lesions at different levels.

Adolescent↗

PubMed1988

Isolation by distance on the Island of Korcula: correlation analysis of distance measures.

Within the framework of holistic anthropological investigations of the rural populations on the Island of Korcula, various measures of biological distances between eight villages were estimated (Mahalanobis' D2 for anthropometric, physiological, and dermatoglyphic traits); socio-cultural similarities and distances were determined (kinship coefficient estimated from migrational data and Hemming similarity measure estimated from linguistic data). A matrix of Spearman's rank correlation coefficients among these measures demonstrated a pattern of interdependencies, which we analysed further by principal components analysis. The first component reflects the cumulative effect of different processes acting on the initial gene distribution over a long period of time; the second component represents initial population structure; and the third component reflects recent migration influences.

Anthropometry↗

PubMed2003

Extraction of correlated gene clusters from multiple genomic data by generalized kernel canonical correlation analysis.

MOTIVATION: A major issue in computational biology is the reconstruction of pathways from several genomic datasets, such as expression data, protein interaction data and phylogenetic profiles. As a first step toward this goal, it is important to investigate the amount of correlation which exists between these data. RESULTS: These methods are successfully tested on their ability to recognize operons in the Escherichia coli genome, from the comparison of three datasets corresponding to functional relationships between genes in metabolic pathways, geometrical relationships along the chromosome, and co-expression relationships as observed by gene expression data.

Algorithms↗

PubMed1993

Mapping schizophrenic negative symptoms onto measures of the patient's speech: set correlational analysis.

We describe a system designed to assess the speech behaviors that inform clinicians about their patients' negative symptoms. Measures are formed into scales to reflect the patient's Pausing, Speech Rate, and Dyadic Interaction with the interviewer. Using set correlation, we examined the associations between the acoustic scales and the clinician's ratings of Flat Affect, Alogia, and Asociality. Over half of the multivariance in the clinical scales was accounted for by the acoustic scales. Unique isomorphisms between the acoustic and rating scales were found for: Dyadic Interaction with Flat Affect; Pause Production with Alogia; and Rate with Asociality.

Adult↗

PubMed1977

[Study of the electric activity of the heart atria in auricular fibrillation with the aid of the instrumental correlation analysis].

The autocorrelation funtion of the electrocardiographic signal in the V1 lead is approximated by the formula of an attenuated consinusoid. Parameters are singled out (median period, attenuation factor) to characterize the atrial activity. A procedure for recording the auto correlation function is described and optimal conditions of its registration are studied. First results following clinical application of the method are reported.

Action Potentials↗

PubMed1996

[Correlativity analysis of detoxicating effect of radix Glycyrrhizae on radix Aconiti preparata in sini decoction].

Based on fixed dosages of Radix Aconiti Preparata and Rhizoma Zingiberis and six different dosages of Radix Glycyrrhizae, six different Sini Decoctions were prepared. The aconitine in these decoctions was determined by TLC-scanning. Statistical analysis was used in the experiment. It has been confirmed that the quantity of aconitine reduces with the increase of the quantity of Radix Glycyrrhizae, assuming a significant negative correlativity, r = -0.9945.

Aconitine↗

PubMed2003

Correlation analysis of visual field thresholds and scanning laser ophthalmoscopic optic nerve head measurements in glaucoma.

In a cross-sectional study of 50 consecutive primary open-angle glaucoma cases, full threshold 30-2 visual fields on Humphrey Visual Field Analyser were correlated to stereometric parameters obtained using a scanning laser ophthalmoscope (HRT II). The strength of linear correlation between the stereometric parameters and visual thresholds was used to generate a correspondence map between the optic disc and the visual field. Rim/disc area ratio and cup/disc area ratio correlated with the visual thresholds at the highest number of points in the visual fields. Thresholds at superior hemifield locations correlated best with the rim/disc area ratio and cup/disc area ratio in the inferonasal sector and the ones in the inferior hemifield correlated best with the rim/disc area ratio and cup/disc area ratio in the superotemporal sector. Optic disc parameters correlated better with inferior field locations and non-edge points than superior field locations and edge points. The data indicate that rim/disc area ratio and cup/disc area ratio measurements on HRT II have a good correlation with visual field damage seen on automated visual fields.

Adult↗

PubMed1989

[Correlation analysis of hemodynamic and morphological parameters in patients with myocarditis].

Central and intrapulmonary hemodynamic parameters were examined in 40 patients with myocarditis. Morphological evidence for endomyocardial biopsy specimens and morphometric findings were also analyzed. Deterioration of myocardial diastolic relaxation was found to closely correlate with the magnitude of cardiosclerotic changes and cardiomyocytic myolysis. A correlation was also established between the morphometric characteristics of the microcirculatory bed and the parameters of myocardial contractility. Functionally deficiently cardiomyocytic hypertrophy was more profound in severe heart failure.

Adolescent↗

PubMed2006

Priming and binding in and across perception and action: a correlational analysis of the internal structure of event files.

Individual performance was compared across three different tasks that tap into the binding of stimulus features in perception, the binding of action features in action planning, and the emergence of stimulus-response bindings ("event files"). Within a task correlations between the size of binding effects were found within visual perception (e.g., the strength of shape-location binding correlated positively with the strength of shape-colour binding) but not between perception and action planning, suggesting different, domain-specific binding mechanisms. To some degree, binding strength was predicted by priming effects of the respective features, especially if these features varied on a dimension that matched the current attentional set.

Analysis of Variance↗