Correlation Structure of Fractional Pearson Diffusions
Leonenko, Nikolai N.; Meerschaert, Mark M.; Sikorskii, Alla
2013-01-01
The stochastic solution to a diffusion equations with polynomial coefficients is called a Pearson diffusion. If the first time derivative is replaced by a Caputo fractional derivative of order less than one, the stochastic solution is called a fractional Pearson diffusion. This paper develops an explicit formula for the covariance function of a fractional Pearson diffusion in steady state, in terms of Mittag-Leffler functions. That formula shows that fractional Pearson diffusions are long range dependent, with a correlation that falls off like a power law, whose exponent equals the order of the fractional derivative. PMID:24089586
The Evolution of Pearson's Correlation Coefficient
ERIC Educational Resources Information Center
Kader, Gary D.; Franklin, Christine A.
2008-01-01
This article describes an activity for developing the notion of association between two quantitative variables. By exploring a collection of scatter plots, the authors propose a nonstandard "intuitive" measure of association; and by examining properties of this measure, they develop the more standard measure, Pearson's Correlation Coefficient. The…
Ghost imaging based on Pearson correlation coefficients
NASA Astrophysics Data System (ADS)
Yu, Wen-Kai; Yao, Xu-Ri; Liu, Xue-Feng; Li, Long-Zhen; Zhai, Guang-Jie
2015-05-01
Correspondence imaging is a new modality of ghost imaging, which can retrieve a positive/negative image by simple conditional averaging of the reference frames that correspond to relatively large/small values of the total intensity measured at the bucket detector. Here we propose and experimentally demonstrate a more rigorous and general approach in which a ghost image is retrieved by calculating a Pearson correlation coefficient between the bucket detector intensity and the brightness at a given pixel of the reference frames, and at the next pixel, and so on. Furthermore, we theoretically provide a statistical interpretation of these two imaging phenomena, and explain how the error depends on the sample size and what kind of distribution the error obeys. According to our analysis, the image signal-to-noise ratio can be greatly improved and the sampling number reduced by means of our new method. Project supported by the National Key Scientific Instrument and Equipment Development Project of China (Grant No. 2013YQ030595) and the National High Technology Research and Development Program of China (Grant No. 2013AA122902).
Approximating Pearson Product-Moment Correlations from Kendall's Tau and Spearman's Rho.
ERIC Educational Resources Information Center
Rupinski, Melvin T.; Dunlap, William P.
1996-01-01
The use of Monte Carlo methods demonstrated that a formula presented by M. G. Kendall for estimating Pearson's rho from tau is somewhat more accurate than a formula presented by K. Pearson for estimating Pearson's rho from a Spearman's rho coefficient. Implications for meta-analysis of correlations are discussed. (SLD)
NASA Astrophysics Data System (ADS)
Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan
2013-09-01
In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Mar?enko-Pastur distribution.
Robustness of Two Formulas to Correct Pearson Correlation for Restriction of Range
ERIC Educational Resources Information Center
tran, minh
2011-01-01
Many research studies involving Pearson correlations are conducted in settings where one of the two variables has a restricted range in the sample. For example, this situation occurs when tests are used for selecting candidates for employment or university admission. Often after selection, there is interest in correlating the selection variable,…
Gender and Age Analyses of NIRS/STAI Pearson Correlation Coefficients at Resting State.
Matsumoto, T; Fuchita, Y; Ichikawa, K; Fukuda, Y; Takemura, N; Sakatani, K
2016-01-01
According to the valence asymmetry hypothesis, the left/right asymmetry of PFC activity is correlated with specific emotional responses to mental stress and personality traits. In a previous study we measured spontaneous oscillation of oxy-Hb concentrations in the bilateral PFC at rest in normal adults employing two-channel portable NIRS and computed the laterality index at rest (LIR). We investigated the Pearson correlation coefficient between the LIR and anxiety levels evaluated by the State-Trait Anxiety Inventory (STAI) test. We found that subjects with right-dominant activity at rest showed higher STAI scores, while those with left dominant oxy-Hb changes at rest showed lower STAI scores such that the Pearson correlation coefficient between LIR and STAI was positive. This study performed Bootstrap analysis on the data and showed the following statistics of the target correlation coefficient: mean?=?0.4925 and lower confidence limit?=?0.177 with confidence level 0.05. Using the KS-test, we demonstrated that the correlation did not depend on age, whereas it did depend on gender. PMID:26782223
Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu
2014-01-01
This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment. PMID:25393286
Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu
2014-01-01
This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment. PMID:25393286
Wang, Luman; Mo, Qiaochu; Wang, Jianxin
2015-01-01
Most current gene coexpression databases support the analysis for linear correlation of gene pairs, but not nonlinear correlation of them, which hinders precisely evaluating the gene-gene coexpression strengths. Here, we report a new database, MIrExpress, which takes advantage of the information theory, as well as the Pearson linear correlation method, to measure the linear correlation, nonlinear correlation, and their hybrid of cell-specific gene coexpressions in immune cells. For a given gene pair or probe set pair input by web users, both mutual information (MI) and Pearson correlation coefficient (r) are calculated, and several corresponding values are reported to reflect their coexpression correlation nature, including MI and r values, their respective rank orderings, their rank comparison, and their hybrid correlation value. Furthermore, for a given gene, the top 10 most relevant genes to it are displayed with the MI, r, or their hybrid perspective, respectively. Currently, the database totally includes 16 human cell groups, involving 20,283 human genes. The expression data and the calculated correlation results from the database are interactively accessible on the web page and can be implemented for other related applications and researches. PMID:26881263
Bishara, Anthony J; Hittner, James B
2012-09-01
It is well known that when data are nonnormally distributed, a test of the significance of Pearson's r may inflate Type I error rates and reduce power. Statistics textbooks and the simulation literature provide several alternatives to Pearson's correlation. However, the relative performance of these alternatives has been unclear. Two simulation studies were conducted to compare 12 methods, including Pearson, Spearman's rank-order, transformation, and resampling approaches. With most sample sizes (n ? 20), Type I and Type II error rates were minimized by transforming the data to a normal shape prior to assessing the Pearson correlation. Among transformation approaches, a general purpose rank-based inverse normal transformation (i.e., transformation to rankit scores) was most beneficial. However, when samples were both small (n ? 10) and extremely nonnormal, the permutation test often outperformed other alternatives, including various bootstrap tests. PMID:22563845
ERIC Educational Resources Information Center
Vos, Pauline
2009-01-01
When studying correlations, how do the three bivariate correlation coefficients between three variables relate? After transforming Pearson's correlation coefficient r into a Euclidean distance, undergraduate students can tackle this problem using their secondary school knowledge of geometry (Pythagoras' theorem and similarity of triangles).…
Booma, P. M.; Prabhakaran, S.; Dhanalakshmi, R.
2014-01-01
Microarray gene expression datasets has concerned great awareness among molecular biologist, statisticians, and computer scientists. Data mining that extracts the hidden and usual information from datasets fails to identify the most significant biological associations between genes. A search made with heuristic for standard biological process measures only the gene expression level, threshold, and response time. Heuristic search identifies and mines the best biological solution, but the association process was not efficiently addressed. To monitor higher rate of expression levels between genes, a hierarchical clustering model was proposed, where the biological association between genes is measured simultaneously using proximity measure of improved Pearson's correlation (PCPHC). Additionally, the Seed Augment algorithm adopts average linkage methods on rows and columns in order to expand a seed PCPHC model into a maximal global PCPHC (GL-PCPHC) model and to identify association between the clusters. Moreover, a GL-PCPHC applies pattern growing method to mine the PCPHC patterns. Compared to existing gene expression analysis, the PCPHC model achieves better performance. Experimental evaluations are conducted for GL-PCPHC model with standard benchmark gene expression datasets extracted from UCI repository and GenBank database in terms of execution time, size of pattern, significance level, biological association efficiency, and pattern quality. PMID:25136661
Wang, Jianji; Zheng, Nanning
2013-09-01
Fractal image compression (FIC) is an image coding technology based on the local similarity of image structure. It is widely used in many fields such as image retrieval, image denoising, image authentication, and encryption. FIC, however, suffers from the high computational complexity in encoding. Although many schemes are published to speed up encoding, they do not easily satisfy the encoding time or the reconstructed image quality requirements. In this paper, a new FIC scheme is proposed based on the fact that the affine similarity between two blocks in FIC is equivalent to the absolute value of Pearson's correlation coefficient (APCC) between them. First, all blocks in the range and domain pools are chosen and classified using an APCC-based block classification method to increase the matching probability. Second, by sorting the domain blocks with respect to APCCs between these domain blocks and a preset block in each class, the matching domain block for a range block can be searched in the selected domain set in which these APCCs are closer to APCC between the range block and the preset block. Experimental results show that the proposed scheme can significantly speed up the encoding process in FIC while preserving the reconstructed image quality well. PMID:23797251
Technology Transfer Automated Retrieval System (TEKTRAN)
Measurements of texture properties related to tenderness at different locations within deboned broiler breast fillets have been used to validate techniques for texture analysis and establish correlations between different texture evaluation methods. However, it has been demonstrated that meat text...
GraĂ±a, M; Termenon, M; Savio, A; Gonzalez-Pinto, A; Echeveste, J; PĂ©rez, J M; Besga, A
2011-09-20
The aim of this paper is to obtain discriminant features from two scalar measures of Diffusion Tensor Imaging (DTI) data, Fractional Anisotropy (FA) and Mean Diffusivity (MD), and to train and test classifiers able to discriminate Alzheimer's Disease (AD) patients from controls on the basis of features extracted from the FA or MD volumes. In this study, support vector machine (SVM) classifier was trained and tested on FA and MD data. Feature selection is done computing the Pearson's correlation between FA or MD values at voxel site across subjects and the indicative variable specifying the subject class. Voxel sites with high absolute correlation are selected for feature extraction. Results are obtained over an on-going study in Hospital de Santiago Apostol collecting anatomical T1-weighted MRI volumes and DTI data from healthy control subjects and AD patients. FA features and a linear SVM classifier achieve perfect accuracy, sensitivity and specificity in several cross-validation studies, supporting the usefulness of DTI-derived features as an image-marker for AD and to the feasibility of building Computer Aided Diagnosis systems for AD based on them. PMID:21839143
Mohamed Salleh, Faridah Hani; Arif, Shereena Mohd; Zainudin, Suhaila; Firdaus-Raih, Mohd
2015-12-01
A gene regulatory network (GRN) is a large and complex network consisting of interacting elements that, over time, affect each other's state. The dynamics of complex gene regulatory processes are difficult to understand using intuitive approaches alone. To overcome this problem, we propose an algorithm for inferring the regulatory interactions from knock-out data using a Gaussian model combines with Pearson Correlation Coefficient (PCC). There are several problems relating to GRN construction that have been outlined in this paper. We demonstrated the ability of our proposed method to (1) predict the presence of regulatory interactions between genes, (2) their directionality and (3) their states (activation or suppression). The algorithm was applied to network sizes of 10 and 50 genes from DREAM3 datasets and network sizes of 10 from DREAM4 datasets. The predicted networks were evaluated based on AUROC and AUPR. We discovered that high false positive values were generated by our GRN prediction methods because the indirect regulations have been wrongly predicted as true relationships. We achieved satisfactory results as the majority of sub-networks achieved AUROC values above 0.5. PMID:26278974
Leonenko, Nikolai N.; Meerschaert, Mark M.
2013-01-01
Pearson diffusions are governed by diffusion equations with polynomial coefficients. Fractional Pearson diffusions are governed by the corresponding time-fractional diffusion equation. They are useful for modeling sub-diffusive phenomena, caused by particle sticking and trapping. This paper provides explicit strong solutions for fractional Pearson diffusions, using spectral methods. It also presents stochastic solutions, using a non-Markovian inverse stable time change. PMID:23626377
NASA Astrophysics Data System (ADS)
Obayashi, Takeshi; Kinoshita, Kengo
2013-01-01
Gene coexpression analysis is a powerful approach to elucidate gene function. We have established and developed this approach using vast amount of publicly available gene expression data measured by microarray techniques. The coexpressed genes are used to estimate gene function of the guide gene or to construct gene coexpression networks. In the case to construct gene networks, researchers should introduce an arbitrary threshold of gene coexpression, because gene coexpression value is continuous value. In the viewpoint to introduce common threshold of gene coexpression, we previously reported rank of Pearson's correlation coefficient (PCC) is more useful than the original PCC value. In this manuscript, we re-assessed the measure of gene coexpression to construct gene coexpression network, and found that mutual rank (MR) of PCC showed better performance than rank of PCC and the original PCC in low false positive rate.
Patients with Pearson Syndrome may have poor food absorption (malabsorption) and low white blood cell counts (neutropenia). Low red cell counts (anemia) can be a major problem, and low platelet counts (thrombocytopenia) can also occur. Symptoms are often present in infancy. Liver and kidney disease usually develop. Examination of the bone marrow under the microscope reveals characteristic holes ("vacuoles") in many cells.
Biochemical abnormalities in Pearson syndrome.
Crippa, Beatrice Letizia; Leon, Eyby; Calhoun, Amy; Lowichik, Amy; Pasquali, Marzia; Longo, Nicola
2015-03-01
Pearson marrow-pancreas syndrome is a multisystem mitochondrial disorder characterized by bone marrow failure and pancreatic insufficiency. Children who survive the severe bone marrow dysfunction in childhood develop Kearns-Sayre syndrome later in life. Here we report on four new cases with this condition and define their biochemical abnormalities. Three out of four patients presented with failure to thrive, with most of them having normal development and head size. All patients had evidence of bone marrow involvement that spontaneously improved in three out of four patients. Unique findings in our patients were acute pancreatitis (one out of four), renal Fanconi syndrome (present in all patients, but symptomatic only in one), and an unusual organic aciduria with 3-hydroxyisobutyric aciduria in one patient. Biochemical analysis indicated low levels of plasma citrulline and arginine, despite low-normal ammonia levels. Regression analysis indicated a significant correlation between each intermediate of the urea cycle and the next, except between ornithine and citrulline. This suggested that the reaction catalyzed by ornithine transcarbamylase (that converts ornithine to citrulline) might not be very efficient in patients with Pearson syndrome. In view of low-normal ammonia levels, we hypothesize that ammonia and carbamylphosphate could be diverted from the urea cycle to the synthesis of nucleotides in patients with Pearson syndrome and possibly other mitochondrial disorders. PMID:25691415
Duthie, R. B.
1979-01-01
This lecture covers some subjects of direct concern to the medical profession contained within the Pearson Report. Each injury group was examined by the Royal Commission, both here and abroad, particular attention being paid to the relationship between tort and social security. By consensus it was proposed that in the majority of fields no-fault compensations should be extended but that the tort system should continue to have a role. Recommendations were also put forward that no damages should be permitted for non-pecuniary loss during the first 3 months and that the full value of the social security benefits should be deductible from all tort damages. Damages for permanent injury or death should be index-linked periodic payments. A new no-fault compensation scheme for road accidents was described as well as a new disabled children's allowance of 4 pounds per week with a mobility allowance at the lower age of 2 years. Medical injury was examined carefully, but it was decided that negligence liability should continue unchanged, with the proviso that the no-fault compensation schemes in New Zealand and in Sweden should be followed. These two schemes have therefore been described in some detail. PMID:159014
Pearson's Functions to Describe FSW Weld Geometry
Lacombe, D.; Coupard, D.; Tcherniaeff, S.; Girot, F.; Gutierrez-Orrantia, M. E.
2011-01-17
Friction stir welding (FSW) is a relatively new joining technique particularly for aluminium alloys that are difficult to fusion weld. In this study, the geometry of the weld has been investigated and modelled using Pearson's functions. It has been demonstrated that the Pearson's parameters (mean, standard deviation, skewness, kurtosis and geometric constant) can be used to characterize the weld geometry and the tensile strength of the weld assembly. Pearson's parameters and process parameters are strongly correlated allowing to define a control process procedure for FSW assemblies which make radiographic or ultrasonic controls unnecessary. Finally, an optimisation using a Generalized Gradient Method allows to determine the geometry of the weld which maximises the assembly tensile strength.
Pearson's Functions to Describe FSW Weld Geometry
NASA Astrophysics Data System (ADS)
Lacombe, D.; Gutierrez-Orrantia, M. E.; Coupard, D.; Tcherniaeff, S.; Girot, F.
2011-01-01
Friction stir welding (FSW) is a relatively new joining technique particularly for aluminium alloys that are difficult to fusion weld. In this study, the geometry of the weld has been investigated and modelled using Pearson's functions. It has been demonstrated that the Pearson's parameters (mean, standard deviation, skewness, kurtosis and geometric constant) can be used to characterize the weld geometry and the tensile strength of the weld assembly. Pearson's parameters and process parameters are strongly correlated allowing to define a control process procedure for FSW assemblies which make radiographic or ultrasonic controls unnecessary. Finally, an optimisation using a Generalized Gradient Method allows to determine the geometry of the weld which maximises the assembly tensile strength.
Corneal endothelial dysfunction in Pearson syndrome.
Kasbekar, Shivani A; Gonzalez-Martin, Jose A; Shafiq, Ayad E; Chandna, Arvind; Willoughby, Colin E
2013-01-01
Mitochondrial disorders are associated with well recognized ocular manifestations. Pearson syndrome is an often fatal, multisystem, mitochondrial disorder that causes variable bone marrow, hepatic, renal and pancreatic exocrine dysfunction. Phenotypic progression of ocular disease in a 12-year-old male with Pearson syndrome is described. This case illustrates phenotypic drift from Pearson syndrome to Kearns-Sayre syndrome given the patient's longevity. Persistent corneal endothelial failure was noted in addition to ptosis, chronic external ophthalmoplegia and mid-peripheral pigmentary retinopathy. We propose that corneal edema resulting from corneal endothelial metabolic pump failure occurs within a spectrum of mitochondrial disorders. PMID:21936618
ERIC Educational Resources Information Center
Campbell, Kathleen T.; Taylor, Dianne L.
1996-01-01
A hypothesized data set is used to illustrate that canonical correlation analysis is a general linear model, subsuming other parametric procedures as special cases. Specific techniques included in analyses are t tests, Pearson correlation, multiple regression, analysis of variance, multivariate analysis of variance, and discriminant analysis. (SLD)
Pearson and Pedagogy: Countering Co-Dependency
ERIC Educational Resources Information Center
Fielder, John
2008-01-01
Noel Pearson and Marcia Langton have both used the terms "co-dependency" and "rescuing" as part of their challenge to the rights-based focus informing Indigenous policies in Australia since the 1960s. Their premise is that the liberal/Left welfare-based agenda, for decades, has largely overlooked Indigenous responsibility. At the same time, they…
Parental Socio-Economic Status as Correlate of Child Labour in Ile-Ife, Nigeria
ERIC Educational Resources Information Center
Elegbeleye, O. S.; Olasupo, M. O.
2012-01-01
This study investigated the relationship between parental socio-economic status and child labour practices in Ile-Ife, Nigeria. The study employed survey method to gather data from 200 parents which constituted the study population. Pearson Product Moment Correlation and t-test statistics were used for the data analyses. The outcome of the studyâ€¦
Parental Socio-Economic Status as Correlate of Child Labour in Ile-Ife, Nigeria
ERIC Educational Resources Information Center
Elegbeleye, O. S.; Olasupo, M. O.
2012-01-01
This study investigated the relationship between parental socio-economic status and child labour practices in Ile-Ife, Nigeria. The study employed survey method to gather data from 200 parents which constituted the study population. Pearson Product Moment Correlation and t-test statistics were used for the data analyses. The outcome of the study…
The Pearson-Readhead Survey from Space
NASA Technical Reports Server (NTRS)
Preston, R. A.; Tingay, S. J.; Jones, D. L.; Lister, M.; Piner, G.; Murphy, D. W.; Meier, D. L.; Pearson, T. J.; Readhead, A. C. S.; Hirabayashi, H.; Kobayashi, H.; Inoue, M.
1988-01-01
The VSOP Space VLBI mission uses the HALCA spacecraft, launched from Japan in February 1997, in conjunction with ground radio observatories around the world to create a high resolution radio-wave length imaging facility. We are using this unique facility to observe a complete sample of Pearson-Readhead Survey sources at 4.8 GHz to determine core brightness temperatures and pc-scale jet properties. The Pearson-Readhead sample has been used for extensive ground-based VLBI survey studies. This sample is ideal for a VSOP survey because the sources are strong, the VSOP u-v coverages are especially good above +350 declination, and multi-epoch ground-based VLBI data and other existing supporting data on these sources exceeds that of any other possible sample. We have chosen to observe a complete subset of this sample that is most likely to show fringes on space-earth baselines. To date we have imaged a majority of the 31 sources in our sample. In addition, we are obtaining matched- resolution 15 GHz observations using the VLBA at epochs close in time to the space VLBI observations to investigate the spectral indices of the source components at high resolution. We gratefully acknowledge the VSOP Project, which is led by the Japanese Institute of Space and Astronautical Science in cooperation with many organizations and radio telescopes around the world. This research was performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.
T test as a parametric statistic
2015-01-01
In statistic tests, the probability distribution of the statistics is important. When samples are drawn from population N (µ, ?2) with a sample size of n, the distribution of the sample mean X? should be a normal distribution N (µ, ?2/n). Under the null hypothesis µ = µ0, the distribution of statistics z=XŻ-µ0?/n should be standardized as a normal distribution. When the variance of the population is not known, replacement with the sample variance s2 is possible. In this case, the statistics XŻ-µ0s/n follows a t distribution (n-1 degrees of freedom). An independent-group t test can be carried out for a comparison of means between two independent groups, with a paired t test for paired data. As the t test is a parametric test, samples should meet certain preconditions, such as normality, equal variances and independence. PMID:26634076
Bayesian Estimation Supersedes the "t" Test
ERIC Educational Resources Information Center
Kruschke, John K.
2013-01-01
Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional "t" tests) when certainty in the estimate is…
Bayesian Estimation Supersedes the "t" Test
ERIC Educational Resources Information Center
Kruschke, John K.
2013-01-01
Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional "t" tests) when certainty in the estimate isâ€¦
A Null Model for Pearson Coexpression Networks
Gobbi, Andrea; Jurman, Giuseppe
2015-01-01
Gene coexpression networks inferred by correlation from high-throughput profiling such as microarray data represent simple but effective structures for discovering and interpreting linear gene relationships. In recent years, several approaches have been proposed to tackle the problem of deciding when the resulting correlation values are statistically significant. This is most crucial when the number of samples is small, yielding a non-negligible chance that even high correlation values are due to random effects. Here we introduce a novel hard thresholding solution based on the assumption that a coexpression network inferred by randomly generated data is expected to be empty. The threshold is theoretically derived by means of an analytic approach and, as a deterministic independent null model, it depends only on the dimensions of the starting data matrix, with assumptions on the skewness of the data distribution compatible with the structure of gene expression levels data. We show, on synthetic and array datasets, that the proposed threshold is effective in eliminating all false positive links, with an offsetting cost in terms of false negative detected edges. PMID:26030917
A product Pearson-type VII density distribution
NASA Astrophysics Data System (ADS)
Nadarajah, Saralees; Kotz, Samuel
2008-01-01
The Pearson-type VII distributions (containing the Student's t distributions) are becoming increasing prominent and are being considered as competitors to the normal distribution. Motivated by real examples in decision sciences, Bayesian statistics, probability theory and Physics, a new Pearson-type VII distribution is introduced by taking the product of two Pearson-type VII pdfs. Various structural properties of this distribution are derived, including its cdf, moments, mean deviation about the mean, mean deviation about the median, entropy, asymptotic distribution of the extreme order statistics, maximum likelihood estimates and the Fisher information matrix. Finally, an application to a Bayesian testing problem is illustrated.
45. Historic American Buildings Survey Elmer R. Pearson, Photographer 1970 ...
45. Historic American Buildings Survey Elmer R. Pearson, Photographer 1970 BUILT0IN STORAGE UNITS, FIRST ATTIC, LOOKING NORTHEAST - Shaker Church Family Main Dwelling House, U.S. Route 20, Hancock, Berkshire County, MA
41. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...
41. Historic American Buildings Survey E. R. Pearson, Photographer 1969 THIRD FLOOR AND ATTIC FLOOR PLAN - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY
40. Historic American Buildings Survey E. R. Pearson, Photographer January ...
40. Historic American Buildings Survey E. R. Pearson, Photographer January 1970 THIRD FLOOR AND ATTIC FLOOR PLAN - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY
Genetics Home Reference: Pearson marrow-pancreas syndrome
... Handbook Glossary Resources Pearson marrow-pancreas syndrome Mitochondrial DNA Related Condition(s) References Quick links to this topic ... This process is called oxidative phosphorylation. Although most DNA is packaged in chromosomes within the nucleus (nuclear ...
3. Historic American Buildings Survey, Elmer R. Pearson, Photographer, 1968 ...
3. Historic American Buildings Survey, Elmer R. Pearson, Photographer, 1968 ELEVATION, LOOKING NORTHWEST. - Shaker Centre Family, Broom Shop, East side of Oxford Road, White Water Park, Hamilton County, OH
Karl Pearson and eugenics: personal opinions and scientific rigor.
Delzell, Darcie A P; Poliak, Cathy D
2013-09-01
The influence of personal opinions and biases on scientific conclusions is a threat to the advancement of knowledge. Expertise and experience does not render one immune to this temptation. In this work, one of the founding fathers of statistics, Karl Pearson, is used as an illustration of how even the most talented among us can produce misleading results when inferences are made without caution or reference to potential bias and other analysis limitations. A study performed by Pearson on British Jewish schoolchildren is examined in light of ethical and professional statistical practice. The methodology used and inferences made by Pearson and his coauthor are sometimes questionable and offer insight into how Pearson's support of eugenics and his own British nationalism could have potentially influenced his often careless and far-fetched inferences. A short background into Pearson's work and beliefs is provided, along with an in-depth examination of the authors' overall experimental design and statistical practices. In addition, portions of the study regarding intelligence and tuberculosis are discussed in more detail, along with historical reactions to their work. PMID:23179067
Spatial trends in Pearson Type III statistical parameters
Lichty, R.W.; Karlinger, M.R.
1995-01-01
Spatial trends in the statistical parameters (mean, standard deviation, and skewness coefficient) of a Pearson Type III distribution of the logarithms of annual flood peaks for small rural basins (less than 90 km2) are delineated using a climate factor CT, (T=2-, 25-, and 100-yr recurrence intervals), which quantifies the effects of long-term climatic data (rainfall and pan evaporation) on observed T-yr floods. Maps showing trends in average parameter values demonstrate the geographically varying influence of climate on the magnitude of Pearson Type III statistical parameters. The spatial trends in variability of the parameter values characterize the sensitivity of statistical parameters to the interaction of basin-runoff characteristics (hydrology) and climate. -from Authors
Reverend Doctor William Pearson in South Kilworth, Leicestershire
NASA Astrophysics Data System (ADS)
Frost, M. A.
2006-12-01
William Pearson (1767-1847) was a 19th-century astronomer, renowned for his work in positional astronomy and the design of astronomical instruments, both practical and instructional. He was a co-founder in 1820 of the Astronomical Society of London, which later became the Royal Astronomical Society, where his portrait hangs. For 30 years of his astronomical career he was the Rector of South Kilworth, a village in Leicestershire, England, where he erected several observatory buildings, as well as extending the village church and building the village schoolroom. This paper documents his activities in South Kilworth.
Space VLBI Observations of the Pearson-Readhead AGN Survey
NASA Astrophysics Data System (ADS)
Lister, M. L.; Preston, R. A.; Tingay, S. J.; Piner, B. G.; Murphy, D. W.; Jones, D. J.; Meier, D. L.; Pearson, T. J.; Readhead, A. C. S.; Hirabayashi, H.; Kobayashi, H.; Inoue, M.
1999-12-01
We are using the VSOP mission to observe a complete sample of Pearson-Readhead Survey AGNs at 4.8 GHz to determine core brightness temperatures and parsec-scale jet properties. The Pearson-Readhead sample has been used for extensive ground-based VLBI survey studies, and is ideal for a VSOP survey because the sources are strong, the VSOP u-v coverages are especially good above +35o declination, and multi-epoch ground-based VLBI data and other existing supporting data on these sources exceed that of any other sample. To date we have imaged a majority of the 31 objects in our sample. In addition, we are obtaining matched-resolution 15 GHz observations using the VLBA at epochs close in time to the space VLBI observations to investigate the spectral indices of the source components at high resolution. We discuss our brightness temperature measurements obtained so far, and interpret our results in the framework of the standard relativistic beaming model for jets in radio-loud AGNs. We gratefully acknowledge the VSOP Project, which is led by the Japanese Institute of Space and Astronautical Science in cooperation with many organizations and radio telescopes around the world. This research was performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.
Shape modeling with family of Pearson distributions: Langmuir waves
NASA Astrophysics Data System (ADS)
Vidojevic, Sonja
2014-10-01
Two major effects of Langmuir wave electric field influence on spectral line shapes are appearance of depressions shifted from unperturbed line and an additional dynamical line broadening. More realistic and accurate models of Langmuir waves are needed to study these effects with more confidence. In this article we present distribution shapes of a high-quality data set of Langmuir waves electric field observed by the WIND satellite. Using well developed numerical techniques, the distributions of the empirical measurements are modeled by family of Pearson distributions. The results suggest that the existing theoretical models of energy conversion between an electron beam and surrounding plasma is more complex. If the processes of the Langmuir wave generation are better understood, the influence of Langmuir waves on spectral line shapes could be modeled better.
Mitochondrial DNA deletion in a patient with combined features of Leigh and Pearson syndromes
Blok, R.B.; Thorburn, D.R.; Danks, D.M.
1994-09-01
We describe a heteroplasmic 4237 bp mitochondrial DNA (mtDNA) deletion in an 11 year old girl who has suffered from progressive illness since birth. She has some features of Leigh syndrome (global developmental delay with regression, brainstem dysfunction and lactic acidosis), together with other features suggestive of Pearson syndrome (history of pancytopenia and failure to thrive). The deletion was present at a level greater than 50% in skeletal muscle, but barely detectable in skin fibroblasts following Southern blot analysis, and only observed in blood following PCR analysis. The deletion spanned nt 9498 to nt 13734, and was flanked by a 12 bp direct repeat. Genes for cytochrome c oxidase subunit III, NADH dehydrogenase subunits 3, 4L, 4 and 5, and tRNAs for glycine, arginine, histidine, serine({sup AGY}) and leucine({sup CUN}) were deleted. Southern blotting also revealed an altered Apa I restriction site which was shown by sequence analysis to be caused by G{r_arrow}A nucleotide substitution at nt 1462 in the 12S rRNA gene. This was presumed to be a polymorphism. No abnormalities of mitochondrial ultrastructure, distribution or of respiratory chain enzyme complexes I-IV in skeletal muscle were observed. Mitochondrial disorders with clinical features overlapping more than one syndrome have been reported previously. This case further demonstrates the difficulty in correlating observed clinical features with a specific mitochondrial DNA mutation.
Technology Transfer Automated Retrieval System (TEKTRAN)
Moisture content, drip loss, expressible fluid, and % salt-induced water gain are widely used to estimate water states and water-holding capacity of raw meat. However, the relationships between these four measurements of broiler pectoralis (p.) major muscle describe are not well described. The objec...
t-Test: The Good, the Bad, the Ugly, & the Remedy
ERIC Educational Resources Information Center
Zhang, Guili
2009-01-01
The t-test is one of the most commonly used significance tests to assess whether the means of two groups are statistically significantly different from each other. The use of t-test has become a natural choice, and rarely practitioners question its appropriateness. This article reviews and discusses t-test's value in providing a rough comparison…
The power of a paired t-test with a covariate.
Hedberg, E C; Ayers, Stephanie
2015-03-01
Many researchers employ the paired t-test to evaluate the mean difference between matched data points. Unfortunately, in many cases this test in inefficient. This paper reviews how to increase the precision of this test through using the mean centered independent variable x, which is familiar to researchers that use analysis of covariance (ANCOVA). We add to the literature by demonstrating how to employ these gains in efficiency as a factor for use in finding the statistical power of the test. The key parameters for this factor are the correlation between the two measures and the variance ratio of the dependent measure on the predictor. The paper then demonstrates how to compute the gains in efficiency a priori to amend the power computations for the traditional paired t-test. We include an example analysis from a recent intervention, Families Preparing the New Generation (Familias Preparando la Nueva Generación). Finally, we conclude with an analysis of extant data to derive reasonable parameter values. PMID:25592936
The power of a paired t-test with a covariate
Hedberg, E. C.; Ayers, Stephanie
2014-01-01
Many researchers employ the paired t-test to evaluate the mean difference between matched data points. Unfortunately, in many cases this test in inefficient. This paper reviews how to increase the precision of this test through using the mean centered independent variable x, which is familiar to researchers that use analysis of covariance (ANCOVA). We add to the literature by demonstrating how to employ these gains in efficiency as a factor for use in finding the statistical power of the test. The key parameters for this factor are the correlation between the two measures and the variance ratio of the dependent measure on the predictor. The paper then demonstrates how to compute the gains in efficiency a priori to amend the power computations for the traditional paired t -test. We include an example analysis from a recent intervention, Families Preparing the New Generation (Familias Preparando la Nueva GeneraciĂłn). Finally, we conclude with an analysis of extant data to derive reasonable parameter values. PMID:25592936
The Beta Distribution,moment method, Karl Pearson and R.A.Fisher
Bowman, Kimiko o
2007-01-01
Simulation studies provide four moment approximating distributions to each of the four parameters of a beta distribution (Pearson Type I). Two of the parameters refer to origin and scale, two to shape (skewness and kurtosis). Type I random number generator is checked out, and the stability of moments of random samples of size n over cycles; particular attention is paid to shape parameter moments. In Type I region of validity (referred to skewness and kurtosis), moment methods become unstable in the neighborhood of Type III ({chi}{sup 2}) line, and ultimately abort. Thus extremely large variances and large higher moments arise. We probe the cause of this phenomenon. Simulation studies are turned to since alternative power series methods are forbiddingly complicated. However, use is made of the delta method to provide asymptotic variances of the estimators, and asymptotic variances of percentage points of the basic distribution. An account of work on the subject by K. Pearson, some of it a century ago, is given. In particular an important paper by Pearson and Filon provides some estimates of probable errors of moment parameter estimators such as the basic distribution parameters, the mode, the skewness and others. The heated controversy between Pearson and Fisher is considered.
Magnello, M E
1998-01-01
Long-standing claims have been made for nearly the entire twentieth century that the biometrician, Karl Pearson, and colleague, W. F. R. Weldon, rejected Mendelism as a theory of inheritance. It is shown that at the end of the nineteenth century Pearson considered various theories of inheritance (including Francis Galton's law of ancestral heredity for characters underpinned by continuous variation), and by 1904 he 'accepted the fundamental idea of Mendel' as a theory of inheritance for discontinuous variation. Moreover, in 1909, he suggested a synthesis of biometry and Mendelism. Despite the many attempts made by a number of geneticists (including R. A. Fisher in 1936) to use Pearson's chi-square (X2, P) goodness-of-fit test on Mendel's data, which produced results that were 'too good to be true', Weldon reached the same conclusion in 1902, but his results were never acknowledged. The geneticist and arch-rival of the biometricians, Williams Bateson, was instead exceptionally critical of this work and interpreted this as Weldon's rejection of Mendelism. Whilst scholarship on Mendel, by historians of science in the last 18 years, has led to a balanced perspective of Mendel, it is suggested that a better balanced and more rounded view of the hereditarian-statistical work of Pearson, Weldon, and the biometricians is long overdue. PMID:11619806
"Describing our whole experience": the statistical philosophies of W. F. R. Weldon and Karl Pearson.
Pence, Charles H
2011-12-01
There are two motivations commonly ascribed to historical actors for taking up statistics: to reduce complicated data to a mean value (e.g., Quetelet), and to take account of diversity (e.g., Galton). Different motivations will, it is assumed, lead to different methodological decisions in the practice of the statistical sciences. Karl Pearson and W. F. R. Weldon are generally seen as following directly in Galton's footsteps. I argue for two related theses in light of this standard interpretation, based on a reading of several sources in which Weldon, independently of Pearson, reflects on his own motivations. First, while Pearson does approach statistics from this "Galtonian" perspective, he is, consistent with his positivist philosophy of science, utilizing statistics to simplify the highly variable data of biology. Weldon, on the other hand, is brought to statistics by a rich empiricism and a desire to preserve the diversity of biological data. Secondly, we have here a counterexample to the claim that divergence in motivation will lead to a corresponding separation in methodology. Pearson and Weldon, despite embracing biometry for different reasons, settled on precisely the same set of statistical tools for the investigation of evolution. PMID:22035721
A Pearson-Type-VII Item Response Model for Assessing Person Fluctuation
ERIC Educational Resources Information Center
Ferrando, Pere J.
2007-01-01
Using Lumsden's Thurstonian fluctuation model as a starting point, this paper attempts to develop a unidimensional item response theory model intended for binary personality items. Under some additional assumptions, a new model is obtained in which the item characteristic curves are defined by a cumulative Pearson-Type-VII distribution, and the…
ERIC Educational Resources Information Center
Pae, Hye K.
2012-01-01
The aim of this study was to apply Rasch modeling to an examination of the psychometric properties of the "Pearson Test of English Academic" (PTE Academic). Analyzed were 140 test-takers' scores derived from the PTE Academic database. The mean age of the participants was 26.45 (SD = 5.82), ranging from 17 to 46. Conformity of the participants'â€¦
ERIC Educational Resources Information Center
Tosolt, Brandelyn; Love, Bettina L.
2011-01-01
Multicultural education is a term with a variety of definitions growing from a number of different disciplines. These authors conducted a content analysis of the Pearson reading program "Good Habits, Great Readers" for grades four and five. The qualitative approach of content analysis allowed researchers to examine text "through the…
ERIC Educational Resources Information Center
Pae, Hye K.
2012-01-01
The aim of this study was to apply Rasch modeling to an examination of the psychometric properties of the "Pearson Test of English Academic" (PTE Academic). Analyzed were 140 test-takers' scores derived from the PTE Academic database. The mean age of the participants was 26.45 (SD = 5.82), ranging from 17 to 46. Conformity of the participants'…
Hashemi Dehaghi, Zahra; Sheikhtaheri, Abbas; Dehnavi, Fariba
2014-01-01
Background: The association between quality of work life and participation in knowledge management is unknown. Objectives: This study aimed to discover the association between quality of work life of nurse managers and their participation in implementing knowledge management. Materials and Methods: This was a correlational study. All nurse managers (71 people) from 11 hospitals affiliated with the Social Security Organization in Tehran, Iran, were included. They were asked to rate their participation in knowledge management and their quality of work life. Data was gathered by a researcher-made questionnaire (May-June 2012). The questionnaire was validated by content and construct validity approaches. Cronbach’s alpha was used to evaluate reliability. Finally, 50 questionnaires were analyzed. The answers were scored and analyzed using mean of scores, T-test, ANOVA (or nonparametric test, if appropriate), Pearson’s correlation coefficient and linear regression. Results: Nurse managers’ performance to implement knowledge management strategies was moderate. A significant correlation was found between quality of work life of nurse managers and their participation in implementing knowledge management strategies (r = 0.82; P < 0.001). The strongest correlations were found between implementation of knowledge management and participation of nurse managers in decision making (r = 0.82; P < 0.001). Conclusions: Improvement of nurse managers’ work life quality, especially in decision-making, may increase their participation in implementing knowledge management. PMID:25763267
When "t"-Tests or Wilcoxon-Mann-Whitney Tests Won't Do
ERIC Educational Resources Information Center
McElduff, Fiona; Cortina-Borja, Mario; Chan, Shun-Kai; Wade, Angie
2010-01-01
"t"-Tests are widely used by researchers to compare the average values of a numeric outcome between two groups. If there are doubts about the suitability of the data for the requirements of a "t"-test, most notably the distribution being non-normal, the Wilcoxon-Mann-Whitney test may be used instead. However, although often applied, both tests mayâ€¦
When "t"-Tests or Wilcoxon-Mann-Whitney Tests Won't Do
ERIC Educational Resources Information Center
McElduff, Fiona; Cortina-Borja, Mario; Chan, Shun-Kai; Wade, Angie
2010-01-01
"t"-Tests are widely used by researchers to compare the average values of a numeric outcome between two groups. If there are doubts about the suitability of the data for the requirements of a "t"-test, most notably the distribution being non-normal, the Wilcoxon-Mann-Whitney test may be used instead. However, although often applied, both tests may…
Using the Student's "t"-Test with Extremely Small Sample Sizes
ERIC Educational Resources Information Center
de Winter, J. C .F.
2013-01-01
Researchers occasionally have to work with an extremely small sample size, defined herein as "N" less than or equal to 5. Some methodologists have cautioned against using the "t"-test when the sample size is extremely small, whereas others have suggested that using the "t"-test is feasible in such a case. The present…
On the Relative Power of the Paired Samples t Test and Wilcoxon's Signed-Ranks Test.
ERIC Educational Resources Information Center
Blair, R. Clifford; Higgins, James J.
Monte Carlo methods were employed to assess the relative power of the paired samples t test and Wilcoxon's signed-ranks test under ten population shapes. Results of the study indicated that: (1) each of the two statistics was more powerful than the other in given situations; (2) the power advantages of the t test under normal theory were small;…
Global-in-time solutions for the isothermal Matovich-Pearson equations
NASA Astrophysics Data System (ADS)
Feireisl, Eduard; Laurençot, Philippe; Mikeli?, Andro
2011-01-01
In this paper we study the Matovich-Pearson equations describing the process of glass fibre drawing. These equations may be viewed as a 1D-reduction of the incompressible Navier-Stokes equations including free boundary, valid for the drawing of a long and thin glass fibre. We concentrate on the isothermal case without surface tension. Then the Matovich-Pearson equations represent a nonlinearly coupled system of an elliptic equation for the axial velocity and a hyperbolic transport equation for the fluid cross-sectional area. We first prove existence of a local solution, and, after constructing appropriate barrier functions, we deduce that the fluid radius is always strictly positive and that the local solution remains in the same regularity class. This estimate leads to the global existence and uniqueness result for this important system of equations.
NASA Astrophysics Data System (ADS)
Singh, Vijay P.; Singh, Kulwant
1985-10-01
The principle of maximum entropy (POME) was used to derive the Pearson type (PT) III distribution. The POME yielded the minimally prejudiced PT III distribution by maximizing the entropy subject to two appropriate constraints which were the mean and the mean of the logarithm of real values about a constant >0. This provided a unique method for parameter estimation. Historical flood data were used to evaluate this method and compare it with the methods of moments and maximum likelihood estimation.
Choosing the Best Correction Formula for the Pearson r[superscript 2] Effect Size
ERIC Educational Resources Information Center
Skidmore, Susan Troncoso; Thompson, Bruce
2011-01-01
In the present Monte Carlo simulation study, the authors compared bias and precision of 7 sampling error corrections to the Pearson r[superscript 2] under 6 x 3 x 6 conditions (i.e., population ? values of 0.0, 0.1, 0.3, 0.5, 0.7, and 0.9, respectively; population shapes normal, skewness = kurtosis = 1, and skewness = -1.5 with kurtosis = 3.5;…
Fisher, Neyman-Pearson or NHST? A tutorial for teaching data testing
Perezgonzalez, Jose D.
2015-01-01
Despite frequent calls for the overhaul of null hypothesis significance testing (NHST), this controversial procedure remains ubiquitous in behavioral, social and biomedical teaching and research. Little change seems possible once the procedure becomes well ingrained in the minds and current practice of researchers; thus, the optimal opportunity for such change is at the time the procedure is taught, be this at undergraduate or at postgraduate levels. This paper presents a tutorial for the teaching of data testing procedures, often referred to as hypothesis testing theories. The first procedure introduced is Fisher's approach to data testingâ€”tests of significance; the second is Neyman-Pearson's approachâ€”tests of acceptance; the final procedure is the incongruent combination of the previous two theories into the current approachâ€”NSHT. For those researchers sticking with the latter, two compromise solutions on how to improve NHST conclude the tutorial. PMID:25784889
Fisher, Neyman-Pearson or NHST? A tutorial for teaching data testing.
Perezgonzalez, Jose D
2015-01-01
Despite frequent calls for the overhaul of null hypothesis significance testing (NHST), this controversial procedure remains ubiquitous in behavioral, social and biomedical teaching and research. Little change seems possible once the procedure becomes well ingrained in the minds and current practice of researchers; thus, the optimal opportunity for such change is at the time the procedure is taught, be this at undergraduate or at postgraduate levels. This paper presents a tutorial for the teaching of data testing procedures, often referred to as hypothesis testing theories. The first procedure introduced is Fisher's approach to data testing-tests of significance; the second is Neyman-Pearson's approach-tests of acceptance; the final procedure is the incongruent combination of the previous two theories into the current approach-NSHT. For those researchers sticking with the latter, two compromise solutions on how to improve NHST conclude the tutorial. PMID:25784889
A modified weighted function method for parameter estimation of Pearson type three distribution
NASA Astrophysics Data System (ADS)
Liang, Zhongmin; Hu, Yiming; Li, Binquan; Yu, Zhongbo
2014-04-01
In this paper, an unconventional method called Modified Weighted Function (MWF) is presented for the conventional moment estimation of a probability distribution function. The aim of MWF is to estimate the coefficient of variation (CV) and coefficient of skewness (CS) from the original higher moment computations to the first-order moment calculations. The estimators for CV and CS of Pearson type three distribution function (PE3) were derived by weighting the moments of the distribution with two weight functions, which were constructed by combining two negative exponential-type functions. The selection of these weight functions was based on two considerations: (1) to relate weight functions to sample size in order to reflect the relationship between the quantity of sample information and the role of weight function and (2) to allocate more weights to data close to medium-tail positions in a sample series ranked in an ascending order. A Monte-Carlo experiment was conducted to simulate a large number of samples upon which statistical properties of MWF were investigated. For the PE3 parent distribution, results of MWF were compared to those of the original Weighted Function (WF) and Linear Moments (L-M). The results indicate that MWF was superior to WF and slightly better than L-M, in terms of statistical unbiasness and effectiveness. In addition, the robustness of MWF, WF, and L-M were compared by designing the Monte-Carlo experiment that samples are obtained from Log-Pearson type three distribution (LPE3), three parameter Log-Normal distribution (LN3), and Generalized Extreme Value distribution (GEV), respectively, but all used as samples from the PE3 distribution. The results show that in terms of statistical unbiasness, no one method possesses the absolutely overwhelming advantage among MWF, WF, and L-M, while in terms of statistical effectiveness, the MWF is superior to WF and L-M.
Omotosho, Philip; Torquati, Alfonso
2016-01-01
Background Increased plasma free fatty acids (FFA) are considered one of the key elements in the pathogenesis of insulin resistance (IR) and type 2 diabetes (T2DM). We hypothesize that, in diabetic patients undergoing laparoscopic Roux-en-Y gastric bypass (LRYGB), a postoperative decrease in FFA will correlate with improved insulin sensitivity (Si). Methods 30 obese (body mass index > 35 kg/m2) patients with a diagnosis of T2DM were studied preoperatively and 12 months after LRYGB in a prospective cohort study. Collected data included intravenous glucose tolerance test (IVGTT), total body composition by DEXA and plasma levels of FFA. Insulin sensitivity analysis from the IVGTT was estimated from minimal model analysis. Pre- and postoperative variables were compared using a paired sample t-test. Relationships between changes in variables were determined with Pearson's correlation test. Results Twelve months after LRYGB the study population showed a significant decrease in body mass index (BMI) (P = 0.001), FFA (P = 0.03), and total body fat (P = 0.03), with an increase in Si (P = 0.001). Postoperative changes in Si significantly correlated (Pearson's r = ?0.53, P=0.01) with change in total body fat, but not with changes in plasma FFA (Pearson's r = ?0.22, P= 0.31). Conclusions Our study challenges the notion that IR is mediated to a significant degree by changes in plasma FFA concentration. Instead, changes in adiposity and consequently changes in adipokines release can be the key players in determining remission of T2DM after RYGB. PMID:24317547
Use of "t"-Test and ANOVA in Career-Technical Education Research
ERIC Educational Resources Information Center
Rojewski, Jay W.; Lee, In Heok; Gemici, Sinan
2012-01-01
Use of t-tests and analysis of variance (ANOVA) procedures in published research from three scholarly journals in career and technical education (CTE) during a recent 5-year period was examined. Information on post hoc analyses, reporting of effect size, alpha adjustments to account for multiple tests, power, and examination of assumptions…
Determining Differences in Efficacy of Two Disinfectants Using t-Tests.
ERIC Educational Resources Information Center
Brehm, Michael A.; And Others
1996-01-01
Presents an experiment to compare the effectiveness of 95% ethanol to 20% bleach as disinfectants using t-tests for the statistical analysis of the data. Reports that bleach is a better disinfectant. Discusses the statistical and practical significance of the results. (JRH)
A comparative evaluation of the estimators of the log Pearson type (LP) 3 distribution
NASA Astrophysics Data System (ADS)
Arora, Kishore; Singh, Vijay P.
1989-01-01
The log Pearson type 3 (LP3) distribution, recommended by the U.S. Water Resources Council (USWRC) in 1967, and subsequently updated in 1975, 1977 and 1981 as the base method of flood frequency analysis in the United States, has been widely used in many parts of the world. However, the estimation procedure for the LP3 distribution recommended by the USWRC has been shown by many investigators to perform rather poorly. In this study several estimation methods for the LP3 distribution, some quite recent, are investigated. The performance of the various methods is then compared via Monte Carlo simulation with the objective of identifying the most robust estimator among them. It is found that besides the USWRC method, the methods based on maximum likelihood and entropy perform poorly. The method based on the moments in real space, and the relatively recent so-called method of mixed moments perform markedly superior to other methods in terms of both resistance and efficiency of estimation or robustness. Therefore, the USWRC guidelines are in need of revision.
Magni, P; Tagliapietra, D; Lardicci, C; Balthis, L; Castelli, A; Como, S; Frangipane, G; Giordani, G; Hyland, J; Maltagliati, F; Pessa, G; Rismondo, A; Tataranni, M; Tomassetti, P; Viaroli, P
2009-04-01
We investigated the applicability of the Pearson-Rosenberg (P-R) conceptual model describing a generalized pattern of response of benthic communities in relation to organic enrichment to Mediterranean Sea coastal lagoons. Consistent with P-R model predictions, benthic diversity and abundance showed two different peaks at low (>2.5-5 mg g(-1)) and high (>25-30 mg g(-1)) total organic carbon (TOC) ranges, respectively. We identified TOC thresholds indicating that risks of reduced benthic diversity should be relatively low at TOC values
Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments
Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.
2004-01-01
[1] The recently developed expected moments algorithm (EMA) [Cohn et al., 1997] does as well as maximum likelihood estimations at estimating log-Pearson type 3 (LP3) flood quantiles using systematic and historical flood information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study compares the performance of Bulletin 17B using the entire sample with and without regional skew with estimators that use regional skew and censor low outliers, including an extended EMA estimator, the conditional probability adjustment (CPA) from Bulletin 17B, and an estimator that uses probability plot regression (PPR) to compute substitute values for low outliers. Estimators that neglect regional skew information do much worse than estimators that use an informative regional skewness estimator. For LP3 data the low outlier rejection procedure generally results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew are generally modest in the skewness range of real interest. Samples contaminated to model actual flood data demonstrate that estimators which give special treatment to low outliers significantly outperform estimators that make no such adjustment.
NASA Astrophysics Data System (ADS)
Zamanzad Ghavidel, Fatemeh; Claesen, JĂĽrgen; Burzykowski, Tomasz; Valkenborg, Dirk
2013-11-01
To extract a genuine peptide signal from a mass spectrum, an observed series of peaks at a particular mass can be compared with the isotope distribution expected for a peptide of that mass. To decide whether the observed series of peaks is similar to the isotope distribution, a similarity measure is needed. In this short communication, we investigate whether the Mahalanobis distance could be an alternative measure for the commonly employed Pearson's Ď‡2 statistic. We evaluate the performance of the two measures by using a controlled MALDI-TOF experiment. The results indicate that Pearson's Ď‡2 statistic has better discriminatory performance than the Mahalanobis distance and is a more robust measure.
The Pearson-Readhead Survey of Compact Extragalactic Radio Sources from Space. I. The Images
NASA Astrophysics Data System (ADS)
Lister, M. L.; Tingay, S. J.; Murphy, D. W.; Piner, B. G.; Jones, D. L.; Preston, R. A.
2001-06-01
We present images from a space-VLBI survey using the facilities of the VLBI Space Observatory Programme (VSOP), drawing our sample from the well-studied Pearson-Readhead survey of extragalactic radio sources. Our survey has taken advantage of long space-VLBI baselines and large arrays of ground antennas, such as the Very Long Baseline Array and European VLBI Network, to obtain high-resolution images of 27 active galactic nuclei and to measure the core brightness temperatures of these sources more accurately than is possible from the ground. A detailed analysis of the source properties is given in accompanying papers. We have also performed an extensive series of simulations to investigate the errors in VSOP images caused by the relatively large holes in the (u,v)-plane when sources are observed near the orbit normal direction. We find that while the nominal dynamic range (defined as the ratio of map peak to off-source error) often exceeds 1000:1, the true dynamic range (map peak to on-source error) is only about 30:1 for relatively complex core-jet sources. For sources dominated by a strong point source, this value rises to approximately 100:1. We find the true dynamic range to be a relatively weak function of the difference in position angle (P.A.) between the jet P.A. and u-v coverage major axis P.A. For regions with low signal-to-noise ratios, typically located down the jet away from the core, large errors can occur, causing spurious features in VSOP images that should be interpreted with caution.
ERIC Educational Resources Information Center
Wagstaff, David A.; Elek, Elvira; Kulis, Stephen; Marsiglia, Flavio
2009-01-01
A nonparametric bootstrap was used to obtain an interval estimate of Pearson's "r," and test the null hypothesis that there was no association between 5th grade students' positive substance use expectancies and their intentions to not use substances. The students were participating in a substance use prevention program in which the unit of…
NASA Astrophysics Data System (ADS)
Kistenev, Yu. V.; Kuzmin, D. A.; Sandykova, E. A.; Shapovalov, A. V.
2015-11-01
An approach to the reduction of the space of the absorption spectra, based on the original criterion for profile analysis of the spectra, was proposed. This criterion dates back to the known statistics chi-square test of Pearson. Introduced criterion allows to quantify the differences of spectral curves.
O'Shaughnessy, Patrick; Cavanaugh, Joseph E
2015-01-01
Industrial hygienists now commonly use direct-reading instruments to evaluate hazards in the workplace. The stored values over time from these instruments constitute a time series of measurements that are often autocorrelated. Given the need to statistically compare two occupational scenarios using values from a direct-reading instrument, a t-test must consider measurement autocorrelation or the resulting test will have a largely inflated type-1 error probability (false rejection of the null hypothesis). A method is described for both the one-sample and two-sample cases which properly adjusts for autocorrelation. This method involves the computation of an "equivalent sample size" that effectively decreases the actual sample size when determining the standard error of the mean for the time series. An example is provided for the one-sample case, and an example is given where a two-sample t-test is conducted for two autocorrelated time series comprised of lognormally distributed measurements. PMID:26011524
Chen, Chun-Ming; Lai, Steven; Chen, Ker-Kong; Lee, Huey-Er
2015-01-01
Purpose. The aim of this study was to determine the correlation between the pharyngeal airway space and head posture after mandibular setback surgery for mandibular prognathism. Materials and Methods. Serial lateral cephalograms of 37 patients with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) were evaluated before (T1) and immediately (T2), between 6 weeks and 3 months (T3), and more than 1 year (T4) after surgery. Paired t-tests and Pearson's correlation analysis were used to evaluate the postoperative changes in all cephalometric parameters, including the mandible, hyoid, head posture (craniocervical angle), and pharyngeal airway space. Results. The mandible and hyoid were set back by 12.8?mm and 4.9?mm, respectively, at T2. Furthermore, the hyoid showed significant inferior movement of 10.7?mm, with an 8?mm increase in the tongue depth. The upper oropharyngeal airway (UOP) shortened by 4.1?mm, the lower oropharyngeal airway (LOP) by 1.7?mm, and the laryngopharyngeal airway by 2?mm. The craniocervical angle showed a significant increase of 2.8°. UOP and LOP showed a significant correlation with the craniocervical angle at T2 and T4. Conclusions. Our findings conclude that the oropharyngeal airway space is significantly decreased and correlated with a change in the head posture after mandibular setback surgery. PMID:25977919
Comparative Power of Student T Test and Mann-Whitney U Test for Unequal Sample Size and Variances.
ERIC Educational Resources Information Center
Zimmerman, Donald W.
1987-01-01
A program obtained random samples from known populations, some of which violated the homogeneity assumption. Student t tests and Mann-Whitney U Tests were performed on the sample value. Where the t test led to incorrect decisions, the use of Mann-Whitney U test in its place led to poorer results. (JAZ)
Reducing Bias and Error in the Correlation Coefficient Due to Nonnormality
ERIC Educational Resources Information Center
Bishara, Anthony J.; Hittner, James B.
2015-01-01
It is more common for educational and psychological data to be nonnormal than to be approximately normal. This tendency may lead to bias and error in point estimates of the Pearson correlation coefficient. In a series of Monte Carlo simulations, the Pearson correlation was examined under conditions of normal and nonnormal data, and it was compared…
Lakens, Daniël
2013-01-01
Effect sizes are the most important outcome of empirical studies. Most articles on effect sizes highlight their importance to communicate the practical significance of results. For scientists themselves, effect sizes are most useful because they facilitate cumulative science. Effect sizes can be used to determine the sample size for follow-up studies, or examining effects across studies. This article aims to provide a practical primer on how to calculate and report effect sizes for t-tests and ANOVA's such that effect sizes can be used in a-priori power analyses and meta-analyses. Whereas many articles about effect sizes focus on between-subjects designs and address within-subjects designs only briefly, I provide a detailed overview of the similarities and differences between within- and between-subjects designs. I suggest that some research questions in experimental psychology examine inherently intra-individual effects, which makes effect sizes that incorporate the correlation between measures the best summary of the results. Finally, a supplementary spreadsheet is provided to make it as easy as possible for researchers to incorporate effect size calculations into their workflow. PMID:24324449
Correlation between cell cycle proteins and hMSH2 in actinic cheilitis and lip cancer.
Lopes, Maria Luiza Diniz de Sousa; de Oliveira, Denise HĂ©len Imaculada Pereira; Sarmento, Dmitry JosĂ© de Santana; Queiroz, LĂ©lia Maria Guedes; Miguel, MĂˇrcia Cristina da Costa; da Silveira, Ă‰ricka Janine Dantas
2016-04-01
This study aims to evaluate and verify the relationship between the immunoexpression of hMSH2, p53 and p21 in actinic cheilitis (AC) and lower lip squamous cell carcinoma (SCC) cases. Forty AC and 40 SCC cases were submitted to immunoperoxidase method and quantitatively analyzed. Expression was compared by Mann-Whitney test, Student t test or one-way ANOVA. To correlate the variables, Pearson's correlation coefficient was calculated. The expression of p53 and p21 showed no significant differences between histopathological grades of AC or lower lip SCC (pÂ >Â 0.05). Immunoexpression of p53 was higher in SCC than in AC (pÂ <Â 0.001), while p21 expression was more observed in AC when compared to SCC group (pÂ =Â 0.006). The AC group revealed an inverse correlation between p53 and hMSH2 expression (rÂ =Â -0.30, pÂ =Â 0.006). Alterations in p53 and p21 expression suggest that these proteins are involved in lower lip carcinogenesis. Moreover, p53 and hMSH2 seem to be interrelated in early events of this process. PMID:26842232
Reassess the t Test: Interact with All Your Data via ANOVA.
Brady, Siobhan M; Burow, Meike; Busch, Wolfgang; Carlborg, Örjan; Denby, Katherine J; Glazebrook, Jane; Hamilton, Eric S; Harmer, Stacey L; Haswell, Elizabeth S; Maloof, Julin N; Springer, Nathan M; Kliebenstein, Daniel J
2015-08-01
Plant biology is rapidly entering an era where we have the ability to conduct intricate studies that investigate how a plant interacts with the entirety of its environment. This requires complex, large studies to measure how plant genotypes simultaneously interact with a diverse array of environmental stimuli. Successful interpretation of the results from these studies requires us to transition away from the traditional standard of conducting an array of pairwise t tests toward more general linear modeling structures, such as those provided by the extendable ANOVA framework. In this Perspective, we present arguments for making this transition and illustrate how it will help to avoid incorrect conclusions in factorial interaction studies (genotype × genotype, genotype × treatment, and treatment × treatment, or higher levels of interaction) that are becoming more prevalent in this new era of plant biology. PMID:26220933
Arndt, S; Turvey, C; Andreasen, N C
1999-01-01
Simple correlations play a large role in the analysis of psychiatric data. They are used to predict outcome, validate new instruments, establish treatment efficacy and find symptom patterns. Researchers and data analysts often face a question about which correlation coefficient to use in a study but are often unaware of the strengths and weaknesses of the alternative correlation measures. The presence of outliers, nonconstant variance, skewed distributions and unequal n are common in psychiatric data and this poses severe problems for many classic statistical methods. We compare Pearson, Spearman and Kendall's correlation coefficients using a large sample of subjects with schizophrenia spectrum disorders who were evaluated with 7 different psychiatric rating scales. Samples sizes ranging from 8 to 50 were evaluated using bootstrapping methods. The criteria for evaluation of the correlations were the type I error rates, power, bias and confidence interval width. Pearson's r did not always control for false positives at the nominal rate and was often unstable. Spearman's r performed better than Pearson's but provided a biased estimate of the true correlation. Spearman's r was also difficult to interpret. Our results suggest that Kendall's tau(b) has many advantages over Pearson's and Spearman's r; when applied to psychiatric data, tau(b) maintained adequate control of type I errors, was nearly as powerful as Pearson's r, provided much tighter confidence intervals and had a clear interpretation. PMID:10221741
Halpin, Peter F; Stam, Henderikus J
2006-01-01
The application of statistical testing in psychological research over the period of 1940-1960 is examined in order to address psychologists' reconciliation of the extant controversy between the Fisher and Neyman-Pearson approaches. Textbooks of psychological statistics and the psychological journal literature are reviewed to examine the presence of what Gigerenzer (1993) called a hybrid model of statistical testing. Such a model is present in the textbooks, although the mathematically incomplete character of this model precludes the appearance of a similarly hybridized approach to statistical testing in the research literature. The implications of this hybrid model for psychological research and the statistical testing controversy are discussed. PMID:17286092
Blair, Sarah; Bardwell, Wayne A.; Podbelewicz-Schuller, Yaffa; Mortimer, Joanne E.
2015-01-01
Background Fatigue is a common complication of adjuvant chemotherapy and compromises the quality of life of breast cancer survivors. We sought to correlate serial hemoglobin (Hb) levels with fatigue in a population of women on adjuvant chemotherapy, none of whom received erythropoietin-stimulating agents or red blood cell transfusions. Patients and Methods Seventy-five women participated in a study using quality-of-life questionnaires to assess changes in need for psychosocial support over time. Questionnaires were administered within 30 days of initiating adjuvant therapy and at 2, 6, and 12 months. Fatigue was assessed by the 36-Item Short-Form Health Survey (SF-36). Hemoglobin levels at each time point were captured retrospectively. Complete data are included for 40 of the 46 women who received adjuvant chemotherapy. Paired-samples t tests were conducted to compare mean SF-36 Energy/Fatigue scores between time points, and independent-samples t tests were conducted for comparisons against norms. Simple correlations (Pearson R) were conducted between SF-36 variables and Hb levels at each time point. Results At 2 months, 23.4% of women had Hb < 11 g/dL compared with 12.9% at 12 months. Compared with norms for women in the general population and breast cancer survivors, these women reported worse fatigue at baseline and at 2 and 6 months. A strong linear relationship was observed between Hb at 2 months and SF-36 Energy/Fatigue scores at 12 months (r = 0.71; P = .002). Conclusion Participants with high fatigue at 12 months had Hb levels at 2 months 13% lower than those with low fatigue. This finding suggests that chemotherapy-induced decline in Hb might be a marker of physiologic reserve. PMID:19073508
Koor, Behrooz Ebrahimzadeh; Nakhaie, Mohammad Reza; Babaie, Saied
2015-01-01
One of the most important problems in patients on hemodialysis (HD) is chronic malnutrition. This study is aimed to assess the prevalence of malnutrition using a subjective global assessment (SGA) in HD patients referred to the Valie ASR Hospital, Arak, Iran. In this descriptive analysis study, 190 HD patients were selected with random sampling. SGA and anthropometric and biochemical measurements were assessed in all patients. Data were analyzed with the Chi-square and t-tests and Pearson correlation coefficient. P <0.05 was considered statistically significant. Of the 190 patients studied, 78 patients (41.1%) were male and 112 patients (58.9%) were female. Sixteen patients were detected to have adequate nutritional status (8.4%), 90 (47.4%) had mild malnutrition and 84 patients (44.2%) had moderate malnutrition. We found a significant negative correlation of SGA score with patient's weight (r = -0.147) and patient's body mass index (BMI) (r = -0.238). Also, it correlated significantly with duration of dialysis treatment (years) (r = 0.404). The SGA score showed a significant negative correlation with mid-arm circumference (MAC) (r = - 0.152). No significant correlation was found between SGA score and mid-arm muscle area. Our study showed that >50% of patients on maintenance HD had mild or moderate malnutrition. There was no case of severe malnutrition. Duration of dialysis treatment and some anthropometric indices (weight, BMI and MAC) also showed a significant correlation with SGA score, which are important to determine the nutritional status of HD patients. PMID:26178540
Novel 5.712 kb mitochondrial DNA deletion in a patient with Pearson syndrome: a case report.
Park, Joonhong; Ryu, Hyejin; Jang, Woori; Chae, Hyojin; Kim, Myungshin; Kim, Yonggoo; Kim, Jiyeon; Lee, Jae Wook; Chung, Nack-Gyun; Cho, Bin; Suh, Byung Kyu
2015-05-01
Pearson marrow?pancreas syndrome (PS) is a progressive multi?organ disorder caused by deletions and duplications of mitochondrial DNA (mtDNA). PS is often fatal in infancy, and the majority of patients with PS succumb to the disease before reaching three?years?of?age, due to septicemia, metabolic acidosis or hepatocellular insufficiency. The present report describes the case of a four?month?old infant with severe normocytic normochromic anemia, vacuolization of hematopoietic precursors and metabolic acidosis. After extensive clinical investigation, the patient was diagnosed with PS, which was confirmed by molecular analysis of mtDNA. The molecular analysis detected a novel large?scale (5.712 kb) deletion spanning nucleotides 8,011 to 13,722 of mtDNA, which lacked direct repeats at the deletion boundaries. The present report is, to the best of our knowledge, the first case reported in South Korea. PMID:25543536
40 CFR Appendix IV to Part 264 - Cochran's Approximation to the Behrens-Fisher Students' t-test
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Cochran's Approximation to the Behrens-Fisher Students' t-test IV Appendix IV to Part 264 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES...
Discrete Pearson distributions
Bowman, K.O.; Shenton, L.R.; Kastenbaum, M.A.
1991-11-01
These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.
Yeom, HeyRi; Blanchard, Steven; Kim, Seokjin; Zunt, Susan; Chu, Tien-Min G
2008-03-01
Conventional histologic or histomorphometric evaluation provides clear evidence of the bone healing process. However, the sample preparation process is tedious and destructive, and the three-dimensional (3D) anisotropic information of the bone trabeculae is compromised. Micro-computed tomography (microCT) has been introduced as an alternative to these traditional evaluation methods. microCT is noninvasive and provides a faster approach to evaluate and quantify cancellous bone. Most previous studies that used microCT have focused on studying trabecular structures of cancellous bone. In this study, we used microCT to analyze the micro-architecture of the regenerated membranous bone using a rabbit cranial defect model. Two 1 cm diameter circular bony defects were created in 12 New Zealand white rabbits. Specimens were harvested at 6 weeks and 12 weeks after surgery and were scanned using a MicroCT machine (Skyscan 1072, Aartselaar, Belgium). The specimens were then sectioned and stained with Goldner's trichrome. Bone volume density (BV/TV), bone surface density (BS/BV), and trabecular thickness (TbTh) were determined from histomorphometric and two-dimensional (2D) and 3D microCT analysis. Pearson's correlation coefficient (gamma), paired t-tests, and intraclass correlation coefficients from measurements between the 2D and 3D microCT and histomorphometry were calculated. There were very strong positive correlations of BV/TV between histomorphometric and 2D or 3D microCT measurements. Correlation between histomorphometric and 2D microCT measurements for BS/BV was moderate, whereas correlation between histomorphometric and 3D microCT measurements was weak. Weak correlations in TbTh among the three methods were found. In conclusion, the present study suggests that, in evaluating micro-architectures in regenerated bones, the correlation between measuring methods vary according to the features measured. PMID:18362725
Chen, Wan-Chi; Chen, Ching-Huey; Lee, Po-Chang; Wang, Wen-Ling
2007-12-01
Quality of life is an important indicator for evaluating therapeutic outcomes and mortality in patients with end-stage renal disease. Few studies have explored the impact of symptom distress and social support on quality of life in this population. A correlational study was designed to examine the influence of symptom distress, social support and demographic characteristics on quality of life in renal transplant recipients. A convenience sample of 113 renal transplant recipients was recruited from a medical center in Southern Taiwan. A structured questionnaire was used to collect data. This four-part tool included: Quality of Life Index--Kidney Transplant Version III, Physical Symptom Distress Scale, Social Support Scale, and demographic characteristics. Data were analyzed by descriptive and inferential statistics (SPSS 10.1 statistical package). Percentage, rank, mean and standard deviation, t-tests, chi-square, ANOVA, Pearson's correlation and multiple regression were computed. Results showed that renal transplant recipients had a moderate quality of life. Social support and symptom distress, age, employment status, and household income significantly explained 28.8% of the variance in quality of life. Findings suggest implications for interventional programming and research aimed toward improving quality of life, including individual and family-based approaches designed to enhance recipients' social support and address effective management of symptoms. Recruiting a transplant clinical nurse specialist to design and implement an intervention program also is recommended. PMID:18080976
Infiltrating mast cells correlate with angiogenesis in bone metastases from gastric cancer patients.
Ammendola, Michele; Marech, Ilaria; Sammarco, Giuseppe; ZuccalĂ , Valeria; Luposella, Maria; Zizzo, Nicola; Patruno, Rosa; Crovace, Alberto; Ruggieri, Eustachio; Zito, Alfredo Francesco; Gadaleta, Cosmo Damiano; Sacco, Rosario; Ranieri, Girolamo
2015-01-01
While gastric cancer is a well established angiogenesis driven tumor, no data has been published regarding angiogenesis stimulated by mast cells (MCs) positive for tryptase in bone metastases from gastric cancer patients (BMGCP). It is well established that MCs play a role in immune responses and more recently it was demonstrated that MCs have been involved in tumor angiogenesis. We analyzed infiltrating MCs and neovascularization in BMGCP diagnosed by histology. A series of 15 stage T3-4N2-3M1 (by AJCC for Gastric Cancer Staging 7th Edition) BMGCP from bone biopsies were selected. Tumour tissue samples were evaluated by mean of immunohistochemistry and image analysis methods in terms of MCs density positive to tryptase (MCDPT), MCs area positive to tryptase (MCAPT), microvascular density (MVD) and endothelial area (EA). A significant correlation between MCDPT, MCAPT, MVD and EA groups to each other was found by Pearson and t-test analysis (r ranged from 0.68 to 0.82; p-value ranged from 0.00 to 0.02). Our very preliminary data suggest that infiltrating MCs positive for tryptase may play a role in BMGCP angiogenesis, and could be further evaluated as a novel target of anti-angiogenic therapy. PMID:25648323
Infiltrating Mast Cells Correlate with Angiogenesis in Bone Metastases from Gastric Cancer Patients
Ammendola, Michele; Marech, Ilaria; Sammarco, Giuseppe; Zuccalŕ, Valeria; Luposella, Maria; Zizzo, Nicola; Patruno, Rosa; Crovace, Alberto; Ruggieri, Eustachio; Zito, Alfredo Francesco; Gadaleta, Cosmo Damiano; Sacco, Rosario; Ranieri, Girolamo
2015-01-01
While gastric cancer is a well established angiogenesis driven tumor, no data has been published regarding angiogenesis stimulated by mast cells (MCs) positive for tryptase in bone metastases from gastric cancer patients (BMGCP). It is well established that MCs play a role in immune responses and more recently it was demonstrated that MCs have been involved in tumor angiogenesis. We analyzed infiltrating MCs and neovascularization in BMGCP diagnosed by histology. A series of 15 stage T3-4N2-3M1 (by AJCC for Gastric Cancer Staging 7th Edition) BMGCP from bone biopsies were selected. Tumour tissue samples were evaluated by mean of immunohistochemistry and image analysis methods in terms of MCs density positive to tryptase (MCDPT), MCs area positive to tryptase (MCAPT), microvascular density (MVD) and endothelial area (EA). A significant correlation between MCDPT, MCAPT, MVD and EA groups to each other was found by Pearson and t-test analysis (r ranged from 0.68 to 0.82; p-value ranged from 0.00 to 0.02). Our very preliminary data suggest that infiltrating MCs positive for tryptase may play a role in BMGCP angiogenesis, and could be further evaluated as a novel target of anti-angiogenic therapy. PMID:25648323
Partial correlation mapping of brain functional connectivity with resting state fMRI
NASA Astrophysics Data System (ADS)
Zhen, Zonglei; Tian, Jie; Qin, Wei; Zhang, Hui
2007-03-01
The methods to detect resting state functional connectivity presented so far mainly focus on Pearson correlation analysis which calculates Pearson Product Moment correlation coefficient between the time series of two distinct voxels or regions to measure the functional dependency between them. Due to artifacts and noises in the data, functional connectivity maps resulting from the Pearson correlation analysis may risk arising from the correlation of interfering signals other than the neural sources. In the paper, partial correlation analysis is proposed to map resting state functional connectivity. By eliminating of the contributions of interfering signals to pairwise correlations between different voxels or regions, partial correlation analysis allows us to measure the real functional connectivity induced by neural activity. Experiments with real fMRI data, demonstrate that mapping functional connectivity with partial correlation analysis leads to disappearance of a considerable part of the functional connectivity networks relative to that from Pearson correlation analysis and showing small, but consistent networks. The results indicate that partial correlation analysis could perform a better mapping of brain functional connectivity than Pearson correlation analysis.
Analysis of correlated ROC areas in diagnostic testing.
Song, H H
1997-03-01
This paper focuses on methods of analysis of areas under receiver operating characteristic (ROC) curves. Analysis of ROC areas should incorporate the correlation structure of repeated measurements taken on the same set of cases and the paucity of measurements per treatment resulting from an effective summarization of cases into a few area measures of diagnostic accuracy. The repeated nature of ROC data has been taken into consideration in the analysis methods previously suggested by Swets and Pickett (1982, Evaluation of Diagnostic Systems: Methods from Signal Detection Theory), Hanley and McNeil (1983, Radiology 148, 839-843), and DeLong, DeLong, and Clarke-Pearson (1988, Biometrics 44, 837-845). DeLong et al.'s procedure is extended to a Wald test for general situations of diagnostic testing. The method of analyzing jackknife pseudovalues by treating them as data is extremely useful when the number of area measures to be tested is quite small. The Wald test based on covariances of multivariate multisample U-statistics is compared with two approaches of analyzing pseudovalues, the univariate mixed-model analysis of variance (ANOVA) for repeated measurements and the three-way factorial ANOVA. Monte Carlo simulations demonstrate that the three tests give good approximation to the nominal size at the 5% levels for large sample sizes, but the paired t-test using ROC areas as data lacks the power of the other three tests and Hanley and McNeil's method is inappropriate for testing diagnostic accuracies. The Wald statistic performs better than the ANOVAs of pseudovalues. Jackknifing schemes of multiple deletion where different structures of normal and diseased distributions are accounted for appear to perform slightly better than simple multiple-deletion schemes but no appreciable power difference is apparent, and deletion of too many cases at a time may sacrifice power. These methods have important applications in diagnostic testing in ROC studies of radiology and of medicine in general. PMID:9147602
NASA Astrophysics Data System (ADS)
Aller, M. F.; Aller, H. D.; Hughes, P. A.
2001-12-01
Using centimeter-band total flux and linear polarization observations of the Pearson-Readhead sample sources systematically obtained with the UMRAO 26-m radio telescope during the past 16 years, we identify the range of variability properties and their temporal changes as functions of both optical and radio morphological classification. We find that our earlier statistical analysis, based on a time window of 6.4 years, did not delineate the full amplitude range of the total flux variability; further, several galaxies exhibit longterm, systematic changes or rather infrequent outbursts requiring long term observations for detection. Using radio classification as a delineator, we confirm, and find additional evidence, that significant changes in flux density can occur in steep spectrum and lobe-dominated objects as well as in compact, flat-spectrum objects. We find that statistically the time-averaged total flux density spectra steepen when longer time windows are included, which we attribute to a selection effect in the source sample. We have identified preferred orientations of the electric vector of the polarized emission (EVPA) in an unbiased manner in several sources, including several QSOs which have exhibited large variations in total flux while maintaining stable EVPAs, and compared these with orientations of the flow direction indicated by VLB morphology. We have looked for systematic, monotonic changes in EVPA which might be expected in the emission from a precessing jet, but none were identified. A Scargle periodogram analysis found no strong evidence for periodicity in any of the sample sources. We thank the NSF for grants AST-8815678, AST-9120224, AST-9421979, and AST-9900723 which provided partial support for this research. The operation of the 26-meter telescope is supported by the University of Michigan Department of Astronomy.
England, J.F., Jr.; Salas, J.D.; Jarrett, R.D.
2003-01-01
The expected moments algorithm (EMA) [Cohn et al., 1997] and the Bulletin 17B [Interagency Committee on Water Data, 1982] historical weighting procedure (B17H) for the log Pearson type III distribution are compared by Monte Carlo computer simulation for cases in which historical and/or paleoflood data are available. The relative performance of the estimators was explored for three cases: fixed-threshold exceedances, a fixed number of large floods, and floods generated from a different parent distribution. EMA can effectively incorporate four types of historical and paleoflood data: floods where the discharge is explicitly known, unknown discharges below a single threshold, floods with unknown discharge that exceed some level, and floods with discharges described in a range. The B17H estimator can utilize only the first two types of historical information. Including historical/paleoflood data in the simulation experiments significantly improved the quantile estimates in terms of mean square error and bias relative to using gage data alone. EMA performed significantly better than B17H in nearly all cases considered. B17H performed as well as EMA for estimating X100 in some limited fixed-threshold exceedance cases. EMA performed comparatively much better in other fixed-threshold situations, for the single large flood case, and in cases when estimating extreme floods equal to or greater than X500. B17H did not fully utilize historical information when the historical period exceeded 200 years. Robustness studies using GEV-simulated data confirmed that EMA performed better than B17H. Overall, EMA is preferred to B17H when historical and paleoflood data are available for flood frequency analysis.
ERIC Educational Resources Information Center
Dugger-Roberts, Cherith A.
2014-01-01
The purpose of this quantitative study was to determine if there was a relationship between the TCAP test and Pearson Benchmark assessment in elementary students' reading and language arts and math performance in a northeastern Tennessee school district. This study involved 3rd, 4th, 5th, and 6th grade students. The study focused on the followingâ€¦
ERIC Educational Resources Information Center
Dugger-Roberts, Cherith A.
2014-01-01
The purpose of this quantitative study was to determine if there was a relationship between the TCAP test and Pearson Benchmark assessment in elementary students' reading and language arts and math performance in a northeastern Tennessee school district. This study involved 3rd, 4th, 5th, and 6th grade students. The study focused on the following…
NASA Astrophysics Data System (ADS)
Takeda, Akira; Takata, Kazuyuki; Nagao, Hirotomo; Wang, Jianqing; Fujiwara, Osamu
We previously measured for healthy subjects and patients who require hemodialysis the complex relative permittivity (?r´-j?r´´) of whole blood, and found that ?r´-axis intercept ?rt´ of straight line approximation to the Cole-Cole plots at frequencies from 200 MHz to 1GHz is significantly different with a level of less than 1% among its averaged values for healthy subjects and patients before and after dialysis, though any correlations between ?rt´ and blood urea nitrogen (BUN) and creatinine being used as main indices for hemodialysis evaluation have not so far been clarified. In this study, to make correlation analyses between the intercept ?rt´ and blood biochemical components for nine patients before and after hemodialysis, we measured six kinds of their blood components including BUN and creatinine, and calculated their Pearson product-moment correlation coefficients for ?rt´ along with significant probability P based on a t-test. It should be noted that P is a reference probability to determine whether or not a null hypothesis can be rejected, and that the P value of 0.05 is commonly used as a significance level for statistical test. As a result, we found that a strong correlation with P < 0.05 is observed between ?rt´ and albumin, while there are not always significant correlations with P > 0.05 between ?rt´ and other blood components including BUN and creatinine. Although albumin is not used as an index for hemodialysis efficiency, it can reflect water amount in blood vessels and liver operation. This finding implies that ?rt´ could be used as an index for evaluating blood viscosity and liver function.
Kumar, Ashish; Rana, Vivek; Aggarwal, Abhai; Chandra, Lokesh
2013-01-01
ABSTRACT Aims: To assess the relationship of anterior tooth fractures with type of occlusion and craniofacial morphology. Materials and methods: The study was conducted on 76 subjects of age group 9 to 13 years with at least one fractured permanent anterior teeth. Lateral cephalograms were taken and study models were prepared for each subject with prior consent of their parents. Then cephalometric tracings were done and overjet was recorded through study models. Statistical analysis used: Standard error of mean (SEM) and unpaired t-test has been applied to test the significant difference between the seven parameters under consideration. Karl Pearson correlation test has also been used to correlate all the parameters used in this study with each other. All the tests were performed at 5 and 1% levels of significance. Results: Frequency of tooth fracture increases with increasing overjet. At 5% level of significance, significant difference were observed between the standard values and observed values for overjet measurement, SNA angle, SNB angle, ANB angle, upper incisor to NA (angle), upper incisor to NA (linear) and interincisal angle for overall data and also for both male and female data separately. Conclusion: Probability of permanent anterior tooth fracture increases with increasing overjet. A significant difference was observed between the standard value and the observed values of all parameters under consideration. How to cite this article: Chaturvedi R, Kumar A, Rana V, Aggarwal A, Chandra L. A Correlation of Permanent Anterior Tooth Fracture with Type of Occlusion and Craniofacial Morphology. Int J Clin Pediatr Dent 2013;6(2):80-84. PMID:25206197
ERIC Educational Resources Information Center
Krijnen, Wim P.
1994-01-01
To assess association between rows of proximity matrices, H. de Vries (1993) introduces weighted average and row-wise average variants for Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank correlation. For all three, the absolute value of the first variant is greater than or equal to the second. (SLD)
Understanding Correlation: Factors that Affect the Size of r
ERIC Educational Resources Information Center
Goodwin, Laura D.; Leech, Nancy L.
2006-01-01
The authors describe and illustrate 6 factors that affect the size of a Pearson correlation: (a) the amount of variability in the data, (b) differences in the shapes of the 2 distributions, (c) lack of linearity, (d) the presence of 1 or more "outliers," (e) characteristics of the sample, and (f) measurement error. Also discussed are ways to…
Xu, Weiyin; Chen, Kejia; Liang, Dayang; Chew, Wee
2009-04-01
A soft-modeling multivariate numerical approach that combines self-modeling curve resolution (SMCR) and mixed Lorentzian-Gaussian curve fitting was successfully implemented for the first time to elucidate spatially and spectroscopically resolved spectral information from infrared imaging data of oral mucosa cells. A novel variant form of the robust band-target entropy minimization (BTEM) SMCR technique, coined as hierarchical BTEM (hBTEM), was introduced to first cluster similar cellular infrared spectra using the unsupervised hierarchical leader-follower cluster analysis (LFCA) and subsequently apply BTEM to clustered subsets of data to reconstruct three protein secondary structure (PSS) pure component spectra-alpha-helix, beta-sheet, and ambiguous structures-that associate with spatially differentiated regions of the cell infrared image. The Pearson VII curve-fitting procedure, which approximates a mixed Lorentzian-Gaussian model for spectral band shape, was used to optimally curve fit the resolved amide I and II bands of various hBTEM reconstructed PSS pure component spectra. The optimized Pearson VII band-shape parameters and peak center positions serve as means to characterize amide bands of PSS spectra found in various cell locations and for approximating their actual amide I/II intensity ratios. The new hBTEM methodology can also be potentially applied to vibrational spectroscopic datasets with dynamic or spatial variations arising from chemical reactions, physical perturbations, pathological states, and the like. PMID:19166806
Lee, Larissa J.; Sadow, Cheryl A.; Russell, Anthony; Viswanathan, Akila N.
2009-11-01
Purpose: To compare high dose rate (HDR) point B to pelvic lymph node dose using three-dimensional-planned brachytherapy for cervical cancer. Methods and Materials: Patients with FIGO Stage IB-IIIB cervical cancer received 70 tandem HDR applications using CT-based treatment planning. The obturator, external, and internal iliac lymph nodes (LN) were contoured. Per fraction (PF) and combined fraction (CF) right (R), left (L), and bilateral (Bil) nodal doses were analyzed. Point B dose was compared with LN dose-volume histogram (DVH) parameters by paired t test and Pearson correlation coefficients. Results: Mean PF and CF doses to point B were R 1.40 Gy +- 0.14 (CF: 7 Gy), L 1.43 +- 0.15 (CF: 7.15 Gy), and Bil 1.41 +- 0.15 (CF: 7.05 Gy). The correlation coefficients between point B and the D100, D90, D50, D2cc, D1cc, and D0.1cc LN were all less than 0.7. Only the D2cc to the obturator and the D0.1cc to the external iliac nodes were not significantly different from the point B dose. Significant differences between R and L nodal DVHs were seen, likely related to tandem deviation from irregular tumor anatomy. Conclusions: With HDR brachytherapy for cervical cancer, per fraction nodal dose approximates a dose equivalent to teletherapy. Point B is a poor surrogate for dose to specific nodal groups. Three-dimensional defined nodal contours during brachytherapy provide a more accurate reflection of delivered dose and should be part of comprehensive planning of the total dose to the pelvic nodes, particularly when there is evidence of pathologic involvement.
Yang, Pei-Lin; Huang, Guey-Shiun; Tsai, Chien-Sung; Lou, Meei-Fang
2015-01-01
Background Poor sleep quality is a common health problem for coronary artery bypass graft patients, however few studies have evaluated sleep quality during the period immediately following hospital discharge. Purpose The aim of this study was to investigate changes in sleep quality and emotional correlates in coronary artery bypass graft patients in Taiwan at 1 week and 1 month after hospital discharge. Methods We used a descriptive correlational design for this study. One week after discharge, 87 patients who had undergone coronary artery bypass surgery completed two structured questionnaires: the Pittsburgh Sleep Quality Index and the Hospital Anxiety and Depression Scale. Three weeks later (1 month after discharge) the patients completed the surveys again. Pearson correlations, t-tests, ANOVA and linear multiple regression analysis were used to analyze the data. Results A majority of the participants had poor sleep quality at 1 week (82.8%) and 1 month (66.7%) post-hospitalization, based on the global score of the Pittsburgh Sleep Quality Index. Despite poor sleep quality at both time-points the sleep quality at 1 month was significantly better than at 1-week post hospitalization. Poorer sleep quality correlated with older age, poorer heart function, anxiety and depression. The majority of participants had normal levels of anxiety at 1 week (69.0%) and 1 month (88.5%) as measured by the Hospital Anxiety and Depression Scale. However, some level of depression was seen at 1 week (78.1%) and 1 month (59.7%). Depression was a significant predictor of sleep quality at 1 week; at 1 month after hospital discharge both anxiety and depression were significant predictors of sleep quality. Conclusion Sleep quality, anxiety and depression all significantly improved 1 month after hospital discharge. However, more than half of the participants continued to have poor sleep quality and some level of depression. Health care personnel should be encouraged to assess sleep and emotional status in patients after coronary artery bypass surgery and offer them appropriate management strategies to improve sleep and reduce anxiety and depression. PMID:26291524
Distance correlation methods for discovering associations in large astrophysical databases
Martínez-Gómez, Elizabeth; Richards, Mercedes T.; Richards, Donald St. P. E-mail: mrichards@astro.psu.edu
2014-01-20
High-dimensional, large-sample astrophysical databases of galaxy clusters, such as the Chandra Deep Field South COMBO-17 database, provide measurements on many variables for thousands of galaxies and a range of redshifts. Current understanding of galaxy formation and evolution rests sensitively on relationships between different astrophysical variables; hence an ability to detect and verify associations or correlations between variables is important in astrophysical research. In this paper, we apply a recently defined statistical measure called the distance correlation coefficient, which can be used to identify new associations and correlations between astrophysical variables. The distance correlation coefficient applies to variables of any dimension, can be used to determine smaller sets of variables that provide equivalent astrophysical information, is zero only when variables are independent, and is capable of detecting nonlinear associations that are undetectable by the classical Pearson correlation coefficient. Hence, the distance correlation coefficient provides more information than the Pearson coefficient. We analyze numerous pairs of variables in the COMBO-17 database with the distance correlation method and with the maximal information coefficient. We show that the Pearson coefficient can be estimated with higher accuracy from the corresponding distance correlation coefficient than from the maximal information coefficient. For given values of the Pearson coefficient, the distance correlation method has a greater ability than the maximal information coefficient to resolve astrophysical data into highly concentrated horseshoe- or V-shapes, which enhances classification and pattern identification. These results are observed over a range of redshifts beyond the local universe and for galaxies from elliptical to spiral.
Zheng, Lei; Diamond, Jerry M; Denton, Debra L
2013-02-01
The U.S. Environmental Protection Agency (U.S. EPA) and state agencies evaluate the toxicity of effluent and surface water samples based on statistical endpoints derived from multiconcentration tests (e.g., no observed effect concentration, EC25). The test of significant toxicity (TST) analysis is a two-sample comparison test that uses Welch's t test to compare organism responses in a sample (effluent or surface water) with responses in a control or site sample. In general, any form of t test (Welch's t included) is appropriate only if the data meet assumptions of normality and homogeneous variances. Otherwise, nonparametric tests are recommended. TST was designed to use Welch's t as the statistical test for all whole effluent toxicity (WET) test data. The authors evaluated the suitability of using Welch's t test for analyzing two-sample toxicity (WET) data, and within the TST approach, by examining the distribution and variances of data from over 2,000 WET tests and by conducting multiple simulations of WET test data. Simulated data were generated having variances and nonnormal distributions similar to observed WET test data for control and the effluent treatment groups. The authors demonstrate that (1) moderately unequal variances (similar to WET data) have little effect on coverage of the t test or Welch t test (for normally distributed data), and (2) for nonnormally distributed data (similar in distribution to WET data) TST, using Welch's t test, has close to nominal coverage on the basis of simulations with up to a ninefold difference in variance between the effluent and control groups (?95th percentile based on observed WET test data). PMID:23172744
Jeanmougin, Marine; de Reynies, Aurelien; Marisa, Laetitia; Paccard, Caroline; Nuel, Gregory; Guedj, Mickael
2010-01-01
High-throughput post-genomic studies are now routinely and promisingly investigated in biological and biomedical research. The main statistical approach to select genes differentially expressed between two groups is to apply a t-test, which is subject of criticism in the literature. Numerous alternatives have been developed based on different and innovative variance modeling strategies. However, a critical issue is that selecting a different test usually leads to a different gene list. In this context and given the current tendency to apply the t-test, identifying the most efficient approach in practice remains crucial. To provide elements to answer, we conduct a comparison of eight tests representative of variance modeling strategies in gene expression data: Welch's t-test, ANOVA [1], Wilcoxon's test, SAM [2], RVM [3], limma [4], VarMixt [5] and SMVar [6]. Our comparison process relies on four steps (gene list analysis, simulations, spike-in data and re-sampling) to formulate comprehensive and robust conclusions about test performance, in terms of statistical power, false-positive rate, execution time and ease of use. Our results raise concerns about the ability of some methods to control the expected number of false positives at a desirable level. Besides, two tests (limma and VarMixt) show significant improvement compared to the t-test, in particular to deal with small sample sizes. In addition limma presents several practical advantages, so we advocate its application to analyze gene expression data. PMID:20838429
ERIC Educational Resources Information Center
Blair, R. Clifford; Higgins, James J.
1985-01-01
Uses Monte Carlo methods to assess the relative power of the paired samples t test and Wilcoxon's signed-ranks test under 10 population shapes. Concludes that, insofar as these two statistics are concerned, the often-repeated claim that parametric tests are more powerful than nonparametric tests is not justified. (Author/CB)
Jaeschke, Lina; Steinbrecher, Astrid; Pischon, Tobias
2015-01-01
Objective Body surface scanners (BS), which visualize a 3D image of the human body, facilitate the computation of numerous body measures, including height, waist circumference (WC) and hip circumference (HC). However, limited information is available regarding validity and reliability of these automated measurements (AM) and their correlation with parameters of the Metabolic Syndrome (MetS) compared to traditional manual measurements (MM). Methods As part of a cross-sectional feasibility study, AM of WC, HC and height were assessed twice in 60 participants using a 3D BS (VitussmartXXL). Additionally, MM were taken by trained personnel according to WHO guidelines. Participants underwent an interview, bioelectrical impedance analysis, and blood pressure measurement. Blood samples were taken to determine HbA1c, HDL-cholesterol, triglycerides, and uric acid. Validity was assessed based on the agreement between AM and MM, using Bland-Altman-plots, correlation analysis, and paired t-tests. Reliability was assessed using intraclass correlation coefficients (ICC) based on two repeated AM. Further, we calculated age-adjusted Pearson correlation for AM and MM with fat mass, systolic blood pressure, HbA1c, HDL-cholesterol, triglycerides, and uric acid. Results Body measures were higher in AM compared to MM but both measurements were strongly correlated (WC, men, difference = 1.5cm, r = 0.97; women, d = 4.7cm, r = 0.96; HC, men, d = 2.3cm, r = 0.97; women, d = 3.0cm; r = 0.98). Reliability was high for all AM (nearly all ICC>0.98). Correlations of WC, HC, and the waist-to-hip ratio (WHR) with parameters of MetS were similar between AM and MM; for example the correlation of WC assessed by AM with HDL-cholesterol was r = 0.35 in men, and r = -0.48 in women, respectively whereas correlation of WC measured manually with HDL cholesterol was r = -0.41 in men, and r = -0.49 in women, respectively. Conclusions Although AM of WC, HC, and WHR are higher when compared to MM based on WHO guidelines, our data indicate good validity, excellent reliability, and similar correlations to parameters of the MetS. PMID:25749283
Correlations between plasma endothelin-1 levels and breakthrough pain in patients with cancer
Yan, Xue-bin; Peng, Tuo-chao; Huang, Dong
2015-01-01
Endothelin-1 (ET-1) may be involved in driving pain in patients with advanced cancer. However, a few studies focus on the role of ET-1 in breakthrough pain (BP). The aim of this pivotal study was to explore the correlation between the plasma (ET-1) level and BP intensity. A total of 40 patients were enrolled in the study, and they were divided into two groups: BP group and non-BP group. Moreover, 20 healthy adults were used as the normal control group. Pain intensity was measured using visual analog scale (VAS) scores of 1–10. Plasma ET-1 levels were detected by an ET radioimmunoassay kit. Subsequently, the correlation of ET-1 level with the VAS score and cancer types was analyzed by Pearson’s correlation coefficient. The plasma ET-1 level in the BP group (35.31±8.02 pg/mL) was higher than that in the non-BP group (29.51±6.78 pg/mL) and the normal control group (24.77±10.10 pg/mL, P<0.05). In addition, the VAS score in the BP group (7.45±0.82) was higher than that in the non-BP group (2.80±1.23, P<0.05). The plasma ET-1 level was positively correlated with the VAS score of the BP group (Pearson’s r=0.42). There was no significant correlation between the plasma ET-1 level and VAS score of the non-BP group (Pearson’s r=?0.22) or/and cancer types (P>0.05). The elevated plasma ET-1 levels were positively related to BP, and targeting ET-1 may provide a novel pain-reducing therapeutic treatment in BP. PMID:26677337
A Study of Correlation of Various Growth Indicators with Chronological Age
Sandhu, Navreet; Puri, Taruna; Gulati, Ritika; Kashyap, Rita
2015-01-01
ABSTRACT Introduction: The aim of this study was to assess the relationship of chronological age with cervical vertebrae skeletal maturation, frontal sinus width and antegonial notch depth and a correlation, if any, among the three variables. Materials and methods: The samples were derived from lateral cephalometric radiographs of 80 subjects (40 males, 40 females; age range: 10 to 19 years). Cervical vertebral development was evaluated by the method of Hassel and Farman, frontal sinus width was measured by the method described by Ertürk and antegonial notch depth as described by Singer et al. The Pearson’s correlation coefficients were estimated to assess the relationship of chronological age with cervical vertebrae skeletal maturation, frontal sinus width and antegonial notch depth. Results: The Pearson’s correlation coefficient were 0.855 (p < 0.001) between chronological age and cervical vertebrae skeletal maturation, and 0.333 (p < 0.001) between chronological age and frontal sinus width. Conclusion: A highly significant positive correlation was found between chronological age and cervical vertebrae skeletal maturation, and between chronological age and frontal sinus width. Nonsignificant correlation was found between chronological age and antegonial notch depth. How to cite this article: Singh S, Sandhu N, Puri T, Gulati R, Kashyap R. A Study of Correlation of Various Growth Indicators with Chronological Age. Int J Clin Pediatr Dent 2015;8(3): 190-195. PMID:26628853
On the correlation of a naturally and an artificially dichotomized variable.
Ulrich, Rolf; Wirtz, Markus
2004-11-01
A method is suggested for estimating the correlation of a naturally (X) and an artificially (Y) dichotomized variable. It is assumed that a normal random variable (L) underlies the artificially dichotomized variable. The proposed correlation coefficient recovers the product moment correlation coefficient between X and L from a fourfold table of X and Y. The suggested correlation coefficient nu is contrasted with the phi correlation and the biserial eta. The biserial eta was proposed by Karl Pearson and is conceptually related to the new correlation coefficient. However, in addition, Pearson's biserial eta invokes the assumption that the marginal distribution of L is normal, which contradicts its basic assumptions and thus does not recover the true correlation of L and X. Finally, an approximation is provided to simplify the calculation of nu and its standard error. PMID:15511306
Liu, Haodi
2016-01-01
Introduction We assessed the correlation between iron deposition and the change of gliocyte metabolism in healthy subjectsâ€™ basal ganglia region, by using 3D-enhanced susceptibility weighted angiography (ESWAN) and proton magnetic resonance spectroscopy (1H-MRS). Material and methods Seventy-seven healthy volunteers (39 female and 38 male subjects; age range: 24â€“82 years old) were enrolled in the experiment including ESWAN and proton MRS sequences, consent for which was provided by themselves or their guardians. For each subject, the mean phase value gained by ESWAN was used to evaluate the iron deposition; choline/creatine (Cho/Cr) and mI/Cr ratios gained by 1H-MRS were used to evaluate gliocyte metabolism in the basal ganglia region of both sides. The paired t test was used to test the difference between the two sides of the basal ganglia region. Linear regression was performed to evaluate the relation between mean phase value and age. Pearson's correlation coefficient was calculated to analyze the relationship between the result of ESWAN and 1H-MRS. Results There was no difference between the two sides of the basal ganglia region in the mean phase value and Cho/Cr. But in mI/Cr the mean phase value of each nucleus in bilateral basal ganglia decreased with increasing age. There are 16 r-values between the mean phase value and Cho/Cr and mI/Cr in bilateral basal ganglia region. And each of all p-values is less than 0.001 (p < 0.001). Conclusions Iron deposition in the bilateral basal ganglia is associated with the change of gliocyte metabolism with increasing age. Iron deposition in each nucleus of the basal ganglia region changes with age. PMID:26925133
Odontometric Sexual Dimorphism: A Sibling Correlation
Sharma, Sonali; Dinkar, Ajit D.; Bedi, Sumit
2014-01-01
Aims and Background: Teeth form an excellent material for anthropological, genetic, odontologic and forensic investigations. The aim of this study was to establish the genetic control of sexual dimorphism in tooth size amongst siblings of Goan children in age range of 14-22 years. Materials and Methods: Twenty-two sibling pairs were selected (22 males and 22 females) to assess genetic control of sexual dimorphism in tooth size. Alginate impressions were obtained for maxillary and mandibular arches and study models were prepared. Measurements were done using Zoom Digimatic Vernier Calipers with a resolution of 0.01 mm. Statistical Analysis: Correlation between mesiodistal and buccolingual tooth sizes amongst siblings was calculated using Pearson’s correlation coefficient. Results: A statistically significant association was found between Mesiodistal Widths of Permanent Maxillary Right and Left Second Molars and between Maxillary Right and Left First Premolars amongst sibling pairs. A statistically significant association was also found between Buccolingual Widths of Mandibular Right and Left First Premolars amongst sibling pairs. This statistically significant correlation found amongst siblings establishes a genetic control over sexual dimorphism in these teeth. Conclusion: The genetic basis of sexual dimorphism in human dentition was ascertained as a significant correlation was found between mesio-distal and bucco-lingual widths of premolars between sibling pairs. PMID:24783145
Quantifying meta-correlations in financial markets
NASA Astrophysics Data System (ADS)
Kenett, Dror Y.; Preis, Tobias; Gur-Gershgoren, Gitit; Ben-Jacob, Eshel
2012-08-01
Financial markets are modular multi-level systems, in which the relationships between the individual components are not constant in time. Sudden changes in these relationships significantly affect the stability of the entire system, and vice versa. Our analysis is based on historical daily closing prices of the 30 components of the Dow Jones Industrial Average (DJIA) from March 15th, 1939 until December 31st, 2010. We quantify the correlation among these components by determining Pearson correlation coefficients, to investigate whether mean correlation of the entire portfolio can be used as a precursor for changes in the index return. To this end, we quantify the meta-correlation - the correlation of mean correlation and index return. We find that changes in index returns are significantly correlated with changes in mean correlation. Furthermore, we study the relationship between the index return and correlation volatility - the standard deviation of correlations for a given time interval. This parameter provides further evidence of the effect of the index on market correlations and their fluctuations. Our empirical findings provide new information and quantification of the index leverage effect, and have implications to risk management, portfolio optimization, and to the increased stability of financial markets.
Kim, H J; Park, S H
2014-01-01
In the present study, the internal adaptation of dentin-composite interfaces with various resin composite materials under conditions of thermomechanical loading was analyzed nondestructively using micro-computed tomography (micro-CT), and these results were compared with analyses of microgaps after sectioning. Additionally, the correlation of internal adaptation with polymerization shrinkage strain and stress was evaluated. Four nonflowable resins, Gradia Direct (GD), Filtek P90 (P9), Filtek Z350 (Z3), and Charisma (CH), and two flowable resins, SDR (SD) and Tetric N-Flow (TF) were used. First, the polymerization shrinkage strain and stress were measured. Then, Class I cavities were prepared in 48 premolars. They were divided randomly into six groups, and the cavities were filled with composites using XP bond. To evaluate the internal adaptation, tooth specimens were immersed in a 25% silver nitrate solution, and micro-CT analysis was performed before and after thermomechanical loading. The silver nitrate penetration (%SP) was measured. After buccolingual sectioning and rhodamine penetration of the specimen, the rhodamine penetration (%RP) was measured using a stereo-microscope. One-way analysis of variance was then used to compare the polymerization shrinkage strain, stress, %SP, and %RP among the groups at a 95% confidence level. A paired t-test was used to compare the %SP before and after thermomechanical loading. Pearson correlation analysis was used to compare the correlation between polymerization shrinkage strain/stress and %SP or %RP to a 95% confidence level. Evaluation of the polymerization shrinkage strain demonstrated that P9 < Z3 â‰¤ GD < CH â‰¤ SD < TF (p<0.05); similarly, evaluation of the polymerization shrinkage stress showed that P9 â‰¤ GD â‰¤ Z3 â‰¤ CH â‰¤ SD < TF (p<0.05). The %SP showed that P9 â‰¤ GD â‰¤ Z3 < CH â‰¤ SD < TF (p<0.05) before loading and that P9 â‰¤ GD â‰¤ Z3 â‰¤ CH â‰¤ SD < TF (p<0.05) after loading. There was a significant difference between the before-loading and after-loading measurements in all groups (p<0.05). Additionally, there was a positive correlation between the %SP and the %RP (r=0.810, p<0.001). Conclusively, the polymerization shrinkage stress and strain were found to be closely related to the internal adaptation of the resin composite restorations. The newly proposed model for the evaluation of internal adaptation using micro-CT and silver nitrate may provide a new measurement for evaluating the internal adaptation of restorations in a nondestructive way. PMID:24111809
ERIC Educational Resources Information Center
Dickens, Rachel H.; Meisinger, Elizabeth B.; Tarar, Jessica M.
2015-01-01
The Comprehensive Test of Phonological Processing-Second Edition (CTOPP-2; Wagner, Torgesen, Rashotte, & Pearson, 2013) is a norm-referenced test that measures phonological processing skills related to reading for individuals aged 4 to 24. According to its authors, the CTOPP-2 may be used to identify individuals who are markedly below theirâ€¦
ERIC Educational Resources Information Center
Dickens, Rachel H.; Meisinger, Elizabeth B.; Tarar, Jessica M.
2015-01-01
The Comprehensive Test of Phonological Processing-Second Edition (CTOPP-2; Wagner, Torgesen, Rashotte, & Pearson, 2013) is a norm-referenced test that measures phonological processing skills related to reading for individuals aged 4 to 24. According to its authors, the CTOPP-2 may be used to identify individuals who are markedly below their…
NASA Astrophysics Data System (ADS)
Redelico, Francisco O.; Proto, Araceli N.; Clippe, Paulette; Ausloos, Marcel
2010-04-01
This work describes a method for searching for globalization evidence within Latin American countries using correlation networks methods. Two correlation measures are used, one based on the usual Pearsons Correlation Coefficient and the other based on Mutual Information. First, it is pointed out there is a core of globalization, where no trade blocs appear, within Latin American countries and second, a hierarchy, from a globalization point of view, is found within these countries. There is no intention to enter into a political consideration here, though any politically prone reader may guess that some further consideration is in order.
Asymmetric correlation matrices: an analysis of financial data
NASA Astrophysics Data System (ADS)
Livan, G.; Rebecchi, L.
2012-06-01
We analyse the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non-symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrix to distinguish between noise and non-trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non-symmetric correlation matrix. We find several non trivial results when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.
Raghunandhan, S; Ravikumar, A; Kameswaran, Mohan; Mandke, Kalyani; Ranjith, R
2015-09-01
Indications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioral responses may be tedious for audiologists in such cases, wherein matching an effective MAP and appropriate MAP becomes the key issue in the habilitation program. In 'Difficult to MAP' scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed, (a) to study the trends in multi-modal electrophysiological tests and behavioral responses sequentially over the first year of implant use, (b) to generate normative data from the above, (c) to correlate the multi-modal electrophysiological thresholds levels with behavioral comfort levels, and (d) to create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis. This prospective study included ten profoundly hearing impaired children aged between 2 and 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, Impedance Telemetry, Neural Response Imaging, Electrically Evoked Stapedial Response Telemetry and Electrically Evoked Auditory Brainstem Response tests at 1, 4, 8 and 12 months of implant use, in conjunction with behavioral Mapping. Trends in electrophysiological and behavioral responses were analyzed using paired t test. By Karl Pearson's correlation method, electrode-wise correlations were derived for NRI thresholds versus Most Comfortable Levels (M-Levels) and offset based (apical, mid-array and basal array) correlations for EABR and ESRT thresholds versus M-Levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-Levels were compared with the behaviorally recorded M-Levels among the cohort, using Cronbach's Alpha Reliability test method for confirming the efficacy of this method. NRI, ESRT and EABR thresholds showed statistically significant positive correlations with behavioral M-Levels, which improved with implant use over time. These correlations were used to derive predicted M-Levels using regression analysis. Such predicted M-Levels were found to be in proximity to the actual behavioral M-Levels recorded among this cohort and proved to be statistically reliable. When clinically applied, this method was found to be successful among subjects of our study group. Although there existed disparities of a few clinical units, between the actual and predicted comfort levels among the subjects, this statistical method was able to provide a working MAP, close to the behavioral MAP used by these children. The results help to infer that behavioral measurements are mandatory to program cochlear implantees, but in cases where they are difficult to obtain, this study method may be used as reference for obtaining additional inputs, in order to set an optimal MAP. The study explores the trends and correlations between electrophysiological tests and behavioral responses, recorded over time among a cohort of cochlear implantees and provides a statistical method which may be used as a guideline to predict optimal behavioral levels in difficult situations among future implantees. In 'Difficult to MAP' scenarios, following a protocol of sequential behavioral programming, in conjunction with electrophysiological correlates will provide the best outcomes. PMID:26405653
Cruz, A D; Esteves, R G; Poiate, I A V P; Portero, P P; Almeida, S M
2014-01-01
This study aimed to objectively evaluate the radiopacity of different dental composites and their subjective influence on diagnosing secondary caries-like lesions and how these results correlate. For objective analysis, three resin specimens (1 mm thick, with a 4-mm internal diameter) were made with four composites: 1) Charisma; 2) Filtek Z250; 3) Prisma AP.H; and 4) Glacier. Three human teeth were selected and then mesio-distally sectioned (1 mm thick) to make the dental specimens. An aluminum (Al) wedge (12 steps, 1 mm thick, 99.8% purity) was used as an internal standard to calculate the radiopacity. For subjective analysis, 20 human teeth were selected and then prepared with a mesio-occluso-distal (MOD) inlay cavity, with half the teeth receiving a round cavity to simulate the carious lesion. The MOD was restored using the composites at four different times. Standardized radiographs were acquired and then digitized (300 dpi and eight-bit TIFF) for both analyses. A histogram objectively measured the pixel intensity values of the images, which were converted into millimeters of Al using linear regressions. Eight observers subjectively evaluated the images using a five-point rating scale to diagnose the caries. The data were statistically analyzed using the Student t-test, the Kappa test, diagnostic testing, and the Pearson correlation coefficient (?=0.05). All materials showed radiopacity values compatible with dental tissues (p>0.05); Glacier was similar to dentin and Prisma AP.H was similar to enamel, while the remaining materials showed a middle radiopacity. Prisma AP.H and Glacier differed (p<0.05) in relation to their accuracy to caries diagnosis, with Glacier having greater accuracy. There was a correlation between objective and subjective analyses with negative linear dependence. An increase in the material's radiopacity could have a subjectively negative influence on the diagnosis of secondary caries; thus, an ideal radiopacity for a dental composite is closer to the dentin image and produces similar attenuation to X-rays than does dentin. PMID:23713807
NASA Astrophysics Data System (ADS)
Aller, M. F.; Aller, H. D.; Hughes, P. A.
2003-03-01
Using UMRAO centimeter-band total flux density and linear polarization monitoring observations of the complete Pearson-Readhead extragalactic source sample obtained between 1984 August and 2001 March, we identify the range of variability in extragalactic objects as functions of optical and radio morphological classification and relate total flux density variations to structural changes in published coeval VLBI maps in selected objects. As expected, variability is common in flat- or inverted-spectrum (?<=0.5) core-dominated QSOs and BL Lac objects. Unexpectedly, we find flux variations in several steep-spectrum sample members, including the commonly adopted flux standard 3C 147. Such variations are characteristically several-year rises or declines or infrequent outbursts, requiring long-term observations for detection: we attribute them to the brightening of weak core components, a change that is suppressed by contributions from extended structure in all but the strongest events, and identify a wavelength dependence for the amplitude of this variability consistent with the presence of opacity in some portions of the jet flow. One morphological class of steep-spectrum objects, the compact symmetric objects (CSOs), characteristically shows only low-level variability. We examine the statistical relation between fractional polarization and radio class based on the data at 14.5 and 4.8 GHz. The blazars typically exhibit flat-to-inverted polarization spectra, a behavior attributed to opacity effects. Among the steep-spectrum objects, the lobe-dominated FR I galaxies have steep fractional polarization spectra, while the FR II galaxies exhibit fractional polarization spectra ranging from inverted to steep, with no identifiable common property that accounts for the range in behavior. For the CSO/gigahertz-peaked spectrum sources, we verify that the fractional polarizations at 4.8 GHz are only of the order of a few tenths of a percent, but at 14.5 GHz we find significantly higher polarizations, ranging from 1% to 3%; this frequency dependence supports a scenario invoking Faraday depolarization by a circumnuclear torus. We have identified preferred orientations of the electric vector of the polarized emission (EVPA) at 14.5 and 4.8 GHz in roughly half of the objects and compared these with orientations of the flow direction indicated by VLBI morphology. When comparing the distributions of the orientation offsets for the BL Lac objects and the QSOs, we find differences in both range and mean value, in support of intrinsic class differences. In the shock-in-jet scenario, we attribute this to the allowed range of obliquities of shocks developing in the flow relative to the flow direction: in the BL Lac objects the shocks are nearly transverse to the flow direction, while in the QSOs they include a broader range of obliquities and can be at large angles to it. The fact that we find long-term stability in EVPA over many events implies that a dominant magnetic field orientation persists; in the core-dominated objects, with small contribution from the underlying quiescent jet, this plausibly suggests that the magnetic field has a long-term memory, with subsequent shock events exhibiting similar EVPA orientation, or, alternatively, the presence of a standing shock in the core. We have looked for systematic, monotonic changes in EVPA, which might be expected in the emission from a precessing jet, a model currently invoked for some AGNs; none were identified. Further, we carried out a Scargle periodogram analysis of the total flux density observations, but found no strong evidence for periodicity in any of the sample sources. The only well-established case in support of both jet precession and periodic variability remains the non-sample member OJ 287.
On the insignificance of Herschel's sunspot correlation
Love, Jeffrey J.
2013-01-01
We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is “statistically significant.” On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are “insignificant.” Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.
On the insignificance of Herschel's sunspot correlation
NASA Astrophysics Data System (ADS)
Love, Jeffrey J.
2013-08-01
We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is "statistically significant." On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are "insignificant." Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.
Weighted network analysis of high-frequency cross-correlation measures
NASA Astrophysics Data System (ADS)
Iori, Giulia; Precup, Ovidiu V.
2007-03-01
In this paper we implement a Fourier method to estimate high-frequency correlation matrices from small data sets. The Fourier estimates are shown to be considerably less noisy than the standard Pearson correlation measures and thus capable of detecting subtle changes in correlation matrices with just a month of data. The evolution of correlation at different time scales is analyzed from the full correlation matrix and its minimum spanning tree representation. The analysis is performed by implementing measures from the theory of random weighted networks.
Predicting missing links via correlation between nodes
NASA Astrophysics Data System (ADS)
Liao, Hao; Zeng, An; Zhang, Yi-Cheng
2015-10-01
As a fundamental problem in many different fields, link prediction aims to estimate the likelihood of an existing link between two nodes based on the observed information. Since this problem is related to many applications ranging from uncovering missing data to predicting the evolution of networks, link prediction has been intensively investigated recently and many methods have been proposed so far. The essential challenge of link prediction is to estimate the similarity between nodes. Most of the existing methods are based on the common neighbor index and its variants. In this paper, we propose to calculate the similarity between nodes by the Pearson correlation coefficient. This method is found to be very effective when applied to calculate similarity based on high order paths. We finally fuse the correlation-based method with the resource allocation method, and find that the combined method can substantially outperform the existing methods, especially in sparse networks.
Giraud, B G; Heumann, J M; Lapedes, A S
1999-05-01
The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such "noncausal correlation" is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range "noncausal" correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation. PMID:11969452
NASA Astrophysics Data System (ADS)
Giraud, B. G.; Heumann, John M.; Lapedes, Alan S.
1999-05-01
The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such ``noncausal correlation'' is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range ``noncausal'' correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation.
Does APO ?4 correlate with MRI changes in Alzheimer's disease?
Doody, R; Azher, S; Haykal, H; Dunn, J; Liao, T; Schneider, L
2000-01-01
OBJECTIVE—To assess the relation between APO E genotype and MRI white matter changes in Alzheimer's disease. The APO ?4 allele is correlated with amyloid angiopathy and other neuropathologies in Alzheimer's disease and could be associated with white matter changes. If so, there should be a dose effect.?METHODS—104 patients with probable Alzheimer's disease (NINCDS-ADRDA criteria) in this Alzheimer's Disease Research Centre were studied. Patients received MRI and APO E genotyping by standardised protocols. Axial MRI was scored (modified Schelten's scale) for the presence and degree of white matter changes and atrophy in several regions by a neuroradiologist blinded to genotype. Total white matter and total atrophy scores were also generated. Data analysis included Pearson's correlation for regional and total imaging scores and analysis of variance (ANOVA) (or Kruskal-Wallis) and ?2 for demographic and disease related variables.?RESULTS—30 patients had no ?4, 53 patients were heterozygous, and 21 patients were homozygous. The three groups did not differ in sex distribution, age of onset, age at MRI, MMSE, clinical dementia rating, or modified Hachinski ischaemia scores. There were no significant correlations between total or regional white matter scores and APO E genotype (Pearson correlation).?CONCLUSIONS—No correlation between total or regional white matter scores and APO E genotype was found. The pathogenesis of white matter changes in Alzheimer's disease may be independent of APO E genotype.?? PMID:11032626
NASA Technical Reports Server (NTRS)
Hall, David M.; Boboltz, David
2013-01-01
This report summarizes the activities of the Washington Correlator for 2012. The Washington Correlator provides up to 80 hours of attended processing per week plus up to 40 hours of unattended operation, primarily supporting Earth Orientation and astrometric observations. In 2012, the major programs supported include the IVS-R4, IVS-INT, APSG, and CRF observing sessions.
NASA Astrophysics Data System (ADS)
Kmetz, Barbara Fotta
2001-07-01
This study sought to identify factors that could be used to predict the success of students on the science portion of the grade ten Connecticut Academic Performance Test (CAPT). While the Connecticut State Department of Education measures student achievement in mathematics, reading and writing in grades 4, 6, and 8, science is assessed only in the grade ten CAPT. Since the CAPT science test does not identify specific areas in need of improvement, it is not possible to determine causes for low test scores. To address this, the study investigated the predictive values of the grade eight Mastery Tests in mathematics and reading, the student ability scores of the Otis-Lennon School Ability Index, and grades in prior science courses. The research sample consisted of five hundred and twenty-five students, member of the graduating classes of 2000 and 2001 in a large suburban high school. Students in the study had participated in the district testing program and their scores for the grade seven Otis-Lennon School Ability Test (OLSAT), the grade eight Connecticut Mastery Tests (CMT) and the grade ten Connecticut Academic Performance Tests (CAPT) were available for analysis. This study investigated correlations between student achievement on the CMT and the science subtest of the CAPT, between OLSAT scores and the CAPT science scores, and between grades in ninth grade science and CAPT science scores. Scores were disaggregated by gender and by course level. Hypotheses 1, 2, 3 and 4 investigated the Pearson Product Moment Correlations of the OLSAT, CMT and course grades with scores on the science portion of the CAPT. Hypothesis 5 compared the scores of male and female students, using the t-test of independent sample means. Calculations showed moderate correlations for hypotheses 1--4, and the hypotheses were accepted. Hypothesis 5 was accepted for one class and rejected for the other. On the whole, female students received higher course grades and lower standardized test grades. Recommendations included the use of reading strategies to improve comprehension, the inclusion of inquiry-based science activities in the curriculum, and the development of valid and reliable classroom assessments that allow students to apply their content knowledge in authentic tasks. The suggestion that cultural and social factors could account for differences in scores of male and female students warrants further study.
DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.
2012-01-01
Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sitesâ€“â€“the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCSâ€“â€“to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1â€“4.2 ka and had 0.6â€“2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 Â± 0.3 ka and 3.5 Â± 0.3 ka, with an average displacement per event of 1.9â€“2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 Â± 0.04 ka and had 0.1â€“0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1â€“2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weberâ€“Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our paleoseismic investigations of the BCS clarify the timing, displacement, and extent of late Holocene earthquakes on the segment, and importantly, confirm the long elapsed time since the most recent earthquake on most of the BCS.
Correlation of the NBME Advanced Clinical Examination in EM and the National EM M4 exams
Hiller, Katherine; Miller, Emily S.; Lawson, Luan; Wald, David; Beeson, Michael; Heitz, Corey; Morrissey, Thomas; House, Joseph; Poznanski, Stacey
2015-01-01
Introduction Since 2011 two online, validated exams for fourth-year emergency medicine (EM) students have been available (National EM M4 Exams). In 2013 the National Board of Medical Examiners offered the Advanced Clinical Examination in Emergency Medicine (EM-ACE). All of these exams are now in widespread use; however, there are no data on how they correlate. This study evaluated the correlation between the EM-ACE exam and the National EM M4 Exams. Methods From May 2013 to April 2014 the EM-ACE and one version of the EM M4 exam were administered sequentially to fourth-year EM students at five U.S. medical schools. Data collected included institution, gross and scaled scores and version of the EM M4 exam. We performed Pearson’s correlation and random effects linear regression. Results 303 students took the EM-ACE and versions 1 (V1) or 2 (V2) of the EM M4 exams (279 and 24, respectively). The mean percent correct for the exams were as follows: EM-ACE 74.8 (SD-8.83), V1 83.0 (SD-6.41), V2 78.5 (SD-7.70). Pearson’s correlation coefficient for the V1/EM-ACE was 0.51 (0.42 scaled) and for the V2/EM-ACE was 0.59 (0.41 scaled). The coefficient of determination for V1/EM-ACE was 0.72 and for V2/EM-ACE = 0.71 (0.86 and 0.49 for scaled scores). The R-squared values were 0.25 and 0.30 (0.18 and 0.13, scaled), respectively. There was significant cluster effect by institution. Conclusion There was moderate positive correlation of student scores on the EM-ACE exam and the National EM M4 Exams. PMID:25671023
Collective Correlations of Brodmann Areas fMRI Study with RMT-Denoising
NASA Astrophysics Data System (ADS)
Burda, Z.; Kornelsen, J.; Nowak, M. A.; Porebski, B.; Sboto-Frankenstein, U.; Tomanek, B.; Tyburczyk, J.
We study collective behavior of Brodmann regions of human cerebral cortex using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory (RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the Brodmann areas with the aid of the Talairach coordinates. Principal Component Analysis (PCA) of the Pearson correlation matrix for 41 different Brodmann regions is carried out to determine their collective activity in the idle state and in the active state stimulated by tapping. The collective brain activity is identified through the statistical analysis of the eigenvectors to the largest eigenvalues of the Pearson correlation matrix. The leading eigenvectors have a large participation ratio. This indicates that several Broadmann regions collectively give rise to the brain activity associated with these eigenvectors. We apply random matrix theory to interpret the underlying multivariate data.
NASA Astrophysics Data System (ADS)
Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.
2014-04-01
Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques.
Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.
2014-01-01
Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640
Richards, Joseph M.; Johnson, Byron Thomas
2002-01-01
The chemistry and toxicity of base flow and urban stormwater were characterized to determine if urban stormwater was degrading the water quality of the Pearson Creek and Wilsons Creek Basins in and near the city of Springfield, Greene County, Missouri. Potentially toxic components of stormwater (nutrients, trace metals, and organic compounds) were identified to help resource managers identify and minimize the sources of toxicants. Nutrient loading to the James River from these two basins (especially the Wilsons Creek Basin) is of some concern because of the potential to degrade downstream water quality. Toxicity related to dissolved trace metal constituents in stormwater does not appear to be a great concern in these two basins. Increased heterotrophic activity, the result of large densities of fecal indicator bacteria introduced into the streams after storm events, could lead to associated dissolved oxygen stress of native biota. Analysis of stormwater samples detected a greater number of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) than were present in base-flow samples. The number and concentrations of pesticides detected in both the base-flow and stormwater samples were similar.Genotoxicity tests were performed to determine the bioavilability of chemical contaminants and determine the potential harmful effects on aquatic biota of Pearson Creek and Wilsons Creek. Genotoxicity was determined from dialysates from both long-term (approximately 30 days) and storm-event (3 to 5 days) semipermeable membrane device (SPMD) samples that were collected in each basin. Toxicity tests of SPMD samples indicated evidence of genotoxins in all SPMD samples. Hepatic activity assessment of one long-term SPMD sample indicated evidence of contaminant uptake in fish. Chemical analyses of the SPMD samples found that relatively few pesticides and pesticide metabolites had been sequestered in the lipid material of the SPMD; however, numerous PAHs and VOCs were detected in both the long-term and the storm-event exposures. It is suspected, based on the compounds detected in the SPMDs and the water samples, that the observed genotoxicity is largely the result of PAHs and VOCs that were probably derived from petroleum inputs or combustion sources. Therefore the water quality and thus the aquatic environments in the Pearson Creek and Wilsons Creek Basins are being degraded by urban derived contaminants.
Edwards, Alan; Larson, Evan; Albright, John
2014-01-01
Background A laterally tracking patella is commonly seen in patients with chronic recurrent lateral patellar dislocations. Clinical appearance of the J-sign occurs when the patella is congruent with the trochlear groove in flexion and moves over the lateral border of the femoral condyle as the lower leg reaches complete extension. A Fulkerson osteotomy procedure corrects this maltracking of the patella by medially transferring the tibial tubercle. There are many radiographic patellofemoral indices that can be used describe this incongruence about the patelloformal joint. The current literature supports the use of the tibial tubercle-trochlear groove (TT- TG) index in determining the appropriate amount medialization of the extensor mechanism. However there is little agreement in how far to transfer the tibial tubercle to best achieve maximum patello- femoral congruency. It is the senior author's belief that lateral patellar edge (LPE) measure on voluntary quadriceps active hyperextension MRI scan has the strongest correlation with final operative tibial tubercle transfer distance needed to achieve maximum patellofemoral congruency. Purpose The purpose of this study was to show that the voluntary quadriceps active hyperextension MRI measurement of lateral patellar edge (LPE) has the strongest correlation with tibial tubercle transfer distance required to achieve maxium patellofemoral congruency intraoperatively in the terminal 30 degrees of active knee extension compared to all other patellofemoral indices measured on axial MRI scans with the knee in voluntary active knee extension to 30 degrees of flexion, passive full extension, and voluntary quadriceps active hyperextension. Study Design Retrospective case series via review of the electronic medical record. Methods Forty-three Fulkerson osteotomy patient charts were reviewed retrospectively. Three different pre-operative axial MRI views were then examined and measured for Tibial Tubercle- Troch-lear Groove (tt-tg), lateral patellar edge (LPE), bisect offset (BSO), and lateral patellar displacement (LPD). Each patient had three MRIs: one with the knee resting in extension, one in voluntary quadriceps active hyperextension, and one in voluntary quadriceps active 30 degree flexion. Statistics were then calculated using Statistical Package for the Social Sciences (SPSS) (IBM corp). Results Tibial tubercle transfer distances required to achieve congruency intraoperatively correlated moderately (0.500-0.300) and were statistically significant (alpha. 050) for passive extension MRI measurement of TT-TG (Pearson- 0.403, alpha 0.010) and LPD (Pearson. 362, alpha 0.022); voluntary quadriceps active hyperextension TT-TG (Pearson 0.487, alpha, 0.001); voluntary quadriceps active flexion TT-TG (Pearson. 548, alpha< 0.001), LPE (Pearson. 332, alpha 0.029), and LPD (Pearson 0.446 alpha. 003). Conclusion The hypothesis that voluntary quadriceps active hyperextension MRI LPE measurement best correlated with tibial tubercle transfer distance was incorrect. The data collected showed correlation and statistical significance for voluntary quadriceps active flexion LPE with required tibal tubercle transfer distance (Pearson 0.34, alpha 0.026). The MRI measurement that best correlated with tibial tubercle transfer distance was voluntary quadriceps active flexion measure of TT-TG (Pearson. 556, alpha< 0.001). PMID:25328455
Sinclair, Michael B. (Albuquerque, NM); Pfeifer, Kent B. (Los Lunas, NM); Flemming, Jeb H. (Albuquerque, NM); Jones, Gary D. (Tijeras, NM); Tigges, Chris P. (Albuquerque, NM)
2010-04-13
A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.
Estimating membrane voltage correlations from extracellular spike trains.
Dorn, Jessy D; Ringach, Dario L
2003-04-01
The cross-correlation coefficient between neural spike trains is a commonly used tool in the study of neural interactions. Two well-known complications that arise in its interpretation are 1) modulations in the correlation coefficient may result solely from changes in the mean firing rate of the cells and 2) the mean firing rates of the neurons impose upper and lower bounds on the correlation coefficient whose absolute values differ by an order of magnitude or more. Here, we propose a model-based approach to the interpretation of spike train correlations that circumvents these problems. The basic idea of our proposal is to estimate the cross-correlation coefficient between the membrane voltages of two cells from their extracellular spike trains and use the resulting value as the degree of correlation (or association) of neural activity. This is done in the context of a model that assumes the membrane voltages of the cells have a joint normal distribution and spikes are generated by a simple thresholding operation. We show that, under these assumptions, the estimation of the correlation coefficient between the membrane voltages reduces to the calculation of a tetrachoric correlation coefficient (a measure of association in nominal data introduced by Karl Pearson) on a contingency table calculated from the spike data. Simulations of conductance-based leaky integrate-and-fire neurons indicate that, despite its simplicity, the technique yields very good estimates of the intracellular membrane voltage correlation from the extracellular spike trains in biologically realistic models. PMID:12686584
Correlation between three color coordinates of human teeth
NASA Astrophysics Data System (ADS)
Lee, Yong-Keun
2014-11-01
The objective was to determine whether there were significant correlations in the three color coordinates within each of two color coordinate systems, such as the Commission Internationale de l'Eclairage (CIE) L*a*b* system, and the lightness, chroma, and hue angle system, of human vital teeth. The color of six maxillary and six mandibular anterior teeth was measured by the Shade Vision System. Pearson correlations between each pair of the color coordinates were determined (?=0.01). The influence of two color coordinates on the other color coordinate was determined with a multiple regression analysis (?=0.01). Based on correlation analyses, all the color coordinate pairs showed significant correlations except for the chroma and hue angle pair. The CIE L* was negatively correlated with the CIE a*, b*, and chroma, but positively correlated with the hue angle. The CIE a* was positively correlated with the CIE b* and chroma. Tooth color coordinates were correlated each other. Lighter teeth were less chromatic both in the CIE a* and b* coordinates. Therefore, it was postulated that the three color coordinates of human teeth were harmonized within certain color attribute ranges, and a lack of correlations in these coordinates might indicate external/internal discolorations and/or anomalies of teeth.
Basnet, Bishal Babu; Parajuli, Prakash Kumar; Singh, Raj Kumar; Suwal, Pramita; Shrestha, Pragya; Baral, Dharanidhar
2015-01-01
Background Establishment of proper occlusal vertical dimension (OVD) is one of the important tasks for successful prosthodontic therapy. An ideal method for determining OVD in terms of cost, time, and instrument requirements has been sought in prosthodontics by various investigators. However, no such single method has been formulated. In the current anthropometric study, the relationship of the length of the thumb to the OVD was tested in two ethnic groups of Nepal, Aryans, and Mongoloids. The result of this study can be useful in determining proper OVD in edentulous patients. Aims and objectives The primary aim of the present study was to evaluate the correlation between the length of the thumb and OVD in Aryan and Mongoloid ethnic groups. The secondary aim was to compare the correlation between OVD and other anatomic measurements (eye–ear distance and pupil-to-rima oris distance) in these ethnicities. Materials and methods The OVD, thumb length, eye–ear distance and distance between pupil of eye and rima oris were measured in a total of 500 adult dentulous volunteers. The correlation between OVD and thumb length as well as other anatomic measurements was checked with Pearson’s product moment correlation coefficient. Linear regression analysis was performed to determine the relationship of OVD to the length of the thumb. Results The thumb length was significantly (P?0.05) correlated with strong and positive values (Pearson’s coefficient =0.874 in the whole population, 0.826 in Aryans, and 0.944 in Mongoloids). Regression analysis showed that thumb length was significantly related to OVD in both ethnic groups. Conclusion Within the limitations of the present study, the result implies that thumb length can be used as an adjunct for establishing OVD in the edentulous patients. PMID:25678817
Gates, Pearson Partner on Common Core
ERIC Educational Resources Information Center
Gewertz, Catherine
2011-01-01
As states and school districts grapple with how to teach the skills outlined in the new common standards, two foundations have announced a partnership aimed at crafting complete, online curricula for those standards in mathematics and English/language arts that span nearly every year of a child's precollegiate education. The announcement last…
Explore Interregional EEG Correlations Changed by Sport Training Using Feature Selection.
Gao, Jia; Wang, Wei; Zhang, Ji
2016-01-01
This paper investigated the interregional correlation changed by sport training through electroencephalography (EEG) signals using the techniques of classification and feature selection. The EEG data are obtained from students with long-time professional sport training and normal students without sport training as baseline. Every channel of the 19-channel EEG signals is considered as a node in the brain network and Pearson Correlation Coefficients are calculated between every two nodes as the new features of EEG signals. Then, the Partial Least Square (PLS) is used to select the top 10 most varied features and Pearson Correlation Coefficients of selected features are compared to show the difference of two groups. Result shows that the classification accuracy of two groups is improved from 88.13% by the method using measurement of EEG overall energy to 97.19% by the method using EEG correlation measurement. Furthermore, the features selected reveal that the most important interregional EEG correlation changed by training is the correlation between left inferior frontal and left middle temporal with a decreased value. PMID:26880880
Explore Interregional EEG Correlations Changed by Sport Training Using Feature Selection
2016-01-01
This paper investigated the interregional correlation changed by sport training through electroencephalography (EEG) signals using the techniques of classification and feature selection. The EEG data are obtained from students with long-time professional sport training and normal students without sport training as baseline. Every channel of the 19-channel EEG signals is considered as a node in the brain network and Pearson Correlation Coefficients are calculated between every two nodes as the new features of EEG signals. Then, the Partial Least Square (PLS) is used to select the top 10 most varied features and Pearson Correlation Coefficients of selected features are compared to show the difference of two groups. Result shows that the classification accuracy of two groups is improved from 88.13% by the method using measurement of EEG overall energy to 97.19% by the method using EEG correlation measurement. Furthermore, the features selected reveal that the most important interregional EEG correlation changed by training is the correlation between left inferior frontal and left middle temporal with a decreased value. PMID:26880880
Esquivel, G B; Lopez, E
1988-10-01
This study explored the correlations among nonverbal reasoning ability, creativity, and academic achievement in gifted minority children, 89 girls and 71 boys in Grades 1 through 8 in a program for gifted. A random half of students from all grade levels were tested at the beginning of the year and the remaining half after 7 mo. with Raven Progressive Matrices, Torrance Tests of Creative Thinking, and the California Achievement Test. Pearson correlations reflected limited relations among these variables except for a significant positive value between creativity and reading achievement. Suggestions for further study and implications for identification procedures and program development were provided. PMID:3217184
Kudlai, Olena; Cutmore, Scott C; Cribb, Thomas H
2015-01-01
Cercariae and metacercariae of three species of the Microphallidae Travassos, 1920 were found in snails and crustaceans from tributaries of the Brisbane River, Queensland, Australia. Specimens of Maritrema brevisacciferum Shimazu et Pearson, 1991 and Microphallus minutus Johnston, 1948, which have previously been reported in Queensland, were found as cercariae in the tateid gastropod Posticobia brazieri (Smith) and as metacercariae of M. brevisacciferum in the atyid shrimp Caridina indistincta Calman and of M. minutus in the parastacid crayfish Cherax dispar Reik. Combined analysis of morphological and molecular data, based on newly generated ITS2 and partial 28S rDNA data, linked cercariae and metacercariae for both species. This is the first report of the first intermediate hosts of M. brevisacciferum and M. minutus. Infections of another unidentified microphallid metacercariae, Microphallidae gen. sp., were found in P. brazieri and C. indistincta. The sequences of metacercarial isolates from both hosts were identical. The data on the Microphallidae from Australia and species that develop in freshwater invertebrates were examined in detail. PMID:26447840
Closure and ratio correlation analysis of lunar chemical and grain size data
NASA Technical Reports Server (NTRS)
Butler, J. C.
1976-01-01
Major element and major element plus trace element analyses were selected from the lunar data base for Apollo 11, 12 and 15 basalt and regolith samples. Summary statistics for each of the six data sets were compiled, and the effects of closure on the Pearson product moment correlation coefficient were investigated using the Chayes and Kruskal approximation procedure. In general, there are two types of closure effects evident in these data sets: negative correlations of intermediate size which are solely the result of closure, and correlations of small absolute value which depart significantly from their expected closure correlations which are of intermediate size. It is shown that a positive closure correlation will arise only when the product of the coefficients of variation is very small (less than 0.01 for most data sets) and, in general, trace elements in the lunar data sets exhibit relatively large coefficients of variation.
Inferring correlation networks from genomic survey data.
Friedman, Jonathan; Alm, Eric J
2012-01-01
High-throughput sequencing based techniques, such as 16S rRNA gene profiling, have the potential to elucidate the complex inner workings of natural microbial communities - be they from the world's oceans or the human gut. A key step in exploring such data is the identification of dependencies between members of these communities, which is commonly achieved by correlation analysis. However, it has been known since the days of Karl Pearson that the analysis of the type of data generated by such techniques (referred to as compositional data) can produce unreliable results since the observed data take the form of relative fractions of genes or species, rather than their absolute abundances. Using simulated and real data from the Human Microbiome Project, we show that such compositional effects can be widespread and severe: in some real data sets many of the correlations among taxa can be artifactual, and true correlations may even appear with opposite sign. Additionally, we show that community diversity is the key factor that modulates the acuteness of such compositional effects, and develop a new approach, called SparCC (available at https://bitbucket.org/yonatanf/sparcc), which is capable of estimating correlation values from compositional data. To illustrate a potential application of SparCC, we infer a rich ecological network connecting hundreds of interacting species across 18 sites on the human body. Using the SparCC network as a reference, we estimated that the standard approach yields 3 spurious species-species interactions for each true interaction and misses 60% of the true interactions in the human microbiome data, and, as predicted, most of the erroneous links are found in the samples with the lowest diversity. PMID:23028285
Pannopnut, Papinwit; Kitporntheranunt, Maethaphan; Paritakul, Panwara; Kongsomboon, Kittipong
2015-01-01
Objective To investigate the correlation between ultrasound measured placental volume and collected umbilical cord blood (UCB) volume in term pregnancy. Material and Methods An observational cross-sectional study of term singleton pregnant women in the labor ward at Maha Chakri Sirindhorn Medical Center was conducted. Placental thickness, height, and width were measured using two-dimensional (2D) ultrasound and calculated for placental volume using the volumetric mathematic model. After the delivery of the baby, UCB was collected and measured for its volume immediately. Then, birth weight, placental weight, and the actual placental volume were analyzed. The Pearson’s correlation was used to determine the correlation between each two variables. Results A total of 35 pregnant women were eligible for the study. The mean and standard deviation of estimated placental volume and actual placental volume were 534±180 mL and 575±118 mL, respectively. The median UCB volume was 140 mL (range 98–220 mL). The UCB volume did not have a statistically significant correlation with the estimated placental volume (correlation coefficient 0.15; p=0.37). However, the UCB volume was significantly correlated with the actual placental volume (correlation coefficient 0.62; p<0.001) and birth weight (correlation coefficient 0.38; p=0.02). Conclusion The estimated placental volume by 2D ultrasound was not significantly correlated with the UCB volume. Further studies to establish the correlation between the UCB volume and the estimated placental volume using other types of placental imaging may be needed. PMID:26097385
Correlation of zinc with oxidative stress biomarkers.
Morales-Suárez-Varela, María; Llopis-González, Agustín; González-Albert, Verónica; López-Izquierdo, Raúl; González-Manzano, Isabel; Cháves, Javier; Huerta-Biosca, Vicente; Martin-Escudero, Juan C
2015-03-01
Hypertension and smoking are related with oxidative stress (OS), which in turn reports on cellular aging. Zinc is an essential element involved in an individual's physiology. The aim of this study was to evaluate the relation of zinc levels in serum and urine with OS and cellular aging and its effect on the development of hypertension. In a Spanish sample with 1500 individuals, subjects aged 20-59 years were selected, whose zinc intake levels fell within the recommended limits. These individuals were classified according to their smoking habits and hypertensive condition. A positive correlation was found (Pearson's C=0.639; p=0.01) between Zn serum/urine quotient and oxidized glutathione levels (GSSG). Finally, risk of hypertension significantly increased when the GSSG levels exceeded the 75 percentile; OR=2.80 (95%CI=1.09-7.18) and AOR=3.06 (95%CI=0.96-9.71). Low zinc levels in serum were related with OS and cellular aging and were, in turn, to be a risk factor for hypertension. PMID:25774936
NASA Astrophysics Data System (ADS)
Sun, Xuelian; Liu, Zixian
2016-02-01
In this paper, a new estimator of correlation matrix is proposed, which is composed of the detrended cross-correlation coefficients (DCCA coefficients), to improve portfolio optimization. In contrast to Pearson's correlation coefficients (PCC), DCCA coefficients acquired by the detrended cross-correlation analysis (DCCA) method can describe the nonlinear correlation between assets, and can be decomposed in different time scales. These properties of DCCA make it possible to improve the investment effect and more valuable to investigate the scale behaviors of portfolios. The minimum variance portfolio (MVP) model and the Mean-Variance (MV) model are used to evaluate the effectiveness of this improvement. Stability analysis shows the effect of two kinds of correlation matrices on the estimation error of portfolio weights. The observed scale behaviors are significant to risk management and could be used to optimize the portfolio selection.
Karnes, F A; McGinnis, J C
1994-06-01
A study of the correlations between scores on the Matrix Analogies Test--Short Form and the WISC--R was conducted with 39 students enrolled in a Saturday program for the intellectually gifted. The Matrix Analogies Test was group-administered and WISC--R scores were obtained from records required for entry into the program. A significant Pearson r of .52 was found between the Matrix Analogies scores and the Performance IQs of the WISC--R; other correlations were not significant. PMID:8058884
Substance Abuse Counselors and Moral Reasoning: Hypothetical and Authentic Dilemmas
ERIC Educational Resources Information Center
Sias, Shari M.
2009-01-01
This exploratory study examined the assumption that the level of moral reasoning (Defining Issues Test; J. R. Rest, 1986) used in solving hypothetical and authentic dilemmas is similar for substance abuse counselors (N = 188). The statistical analyses used were paired-sample t tests, Pearson product-moment correlation, and simultaneous multiple…
Substance Abuse Counselors and Moral Reasoning: Hypothetical and Authentic Dilemmas
ERIC Educational Resources Information Center
Sias, Shari M.
2009-01-01
This exploratory study examined the assumption that the level of moral reasoning (Defining Issues Test; J. R. Rest, 1986) used in solving hypothetical and authentic dilemmas is similar for substance abuse counselors (N = 188). The statistical analyses used were paired-sample t tests, Pearson product-moment correlation, and simultaneous multipleâ€¦
Correlation Between University Students' Kinematic Achievement and Learning Styles
NASA Astrophysics Data System (ADS)
Çirkino?lu, A. G.; Dem&ircidot, N.
2007-04-01
In the literature, some researches on kinematics revealed that students have many difficulties in connecting graphs and physics. Also some researches showed that the method used in classroom affects students' further learning. In this study the correlation between university students' kinematics achieve and learning style are investigated. In this purpose Kinematics Achievement Test and Learning Style Inventory were applied to 573 students enrolled in general physics 1 courses at Balikesir University in the fall semester of 2005-2006. Kinematics Test, consists of 12 multiple choose and 6 open ended questions, was developed by researchers to assess students' understanding, interpreting, and drawing graphs. Learning Style Inventory, a 24 items test including visual, auditory, and kinesthetic learning styles, was developed and used by Barsch. The data obtained from in this study were analyzed necessary statistical calculations (T-test, correlation, ANOVA, etc.) by using SPSS statistical program. Based on the research findings, the tentative recommendations are made.
Correlation between centrality metrics and their application to the opinion model
NASA Astrophysics Data System (ADS)
Li, Cong; Li, Qian; Van Mieghem, Piet; Stanley, H. Eugene; Wang, Huijuan
2015-03-01
In recent decades, a number of centrality metrics describing network properties of nodes have been proposed to rank the importance of nodes. In order to understand the correlations between centrality metrics and to approximate a high-complexity centrality metric by a strongly correlated low-complexity metric, we first study the correlation between centrality metrics in terms of their Pearson correlation coefficient and their similarity in ranking of nodes. In addition to considering the widely used centrality metrics, we introduce a new centrality measure, the degree mass. The mth-order degree mass of a node is the sum of the weighted degree of the node and its neighbors no further than m hops away. We find that the betweenness, the closeness, and the components of the principal eigenvector of the adjacency matrix are strongly correlated with the degree, the 1st-order degree mass and the 2nd-order degree mass, respectively, in both network models and real-world networks. We then theoretically prove that the Pearson correlation coefficient between the principal eigenvector and the 2nd-order degree mass is larger than that between the principal eigenvector and a lower order degree mass. Finally, we investigate the effect of the inflexible contrarians selected based on different centrality metrics in helping one opinion to compete with another in the inflexible contrarian opinion (ICO) model. Interestingly, we find that selecting the inflexible contrarians based on the leverage, the betweenness, or the degree is more effective in opinion-competition than using other centrality metrics in all types of networks. This observation is supported by our previous observations, i.e., that there is a strong linear correlation between the degree and the betweenness, as well as a high centrality similarity between the leverage and the degree.
Spatial correlation structure of monthly rainfall at a mesoscale region of north-eastern Bohemia
NASA Astrophysics Data System (ADS)
Svoboda, Vojt?ch; Máca, Petr; Hanel, Martin; Pech, Pavel
2015-07-01
The spatial correlation structure of monthly rainfall was analysed using data from 38 rain gauges located in north-eastern Bohemia. Three different inter-station correlation measures—Pearson's correlation coefficient, Spearman's rank-order correlation coefficient and Kendall's tau rank correlation coefficient—were estimated using monthly rainfall records from a recent 31-year period. Six different theoretical parametric correlation models were identified using the nonlinear least squares method. The spatial correlation structure was described using the fitted parameters. Comparison of estimated correlation models showed that, as measured by standard error, the best fitted was a two-parameter exponential model. The relationships between parameters of the exponential two-parameter model were further explored and described. The temporal variability of correlation showed trends in the fitted parameters over the studied period. On a seasonal basis, the correlation between the stations was stronger in autumn and winter than in spring and summer. The spatial variability of estimated parameters revealed that parameters of Matérn and two-parameter exponential models were dependent on altitude.
Correlation Between Pain, Fear of Falling and Disability in Low Back Pain
Pal, Bharat Prakash
2015-01-01
Objective To ascertain if there is a correlation between low back pain (LBP), fear of falling, and disability so that the patients with LBP are aware of the fact that other problems may occur with LBP. Hence, steps can be taken for decreasing the fear of falling and disability in order to improve the condition of patients. Methods A sample size of 100 patients with low back pain, with a range of ages from 40 to 73 years, participated in the study. The Falls Efficacy Scale was used to assess the fear of falling and the Oswestry Disability Index was used to assess the disability and pain in LBP individuals. Results The Pearson correlation analysis signifies the relationship between pain, fear of falling, and disability in LBP. Conclusion First, LBP increases the fear of falling. Second, LBP can result in a person becoming disabled. Third, the fear of falling and disability are correlated with each other. PMID:26605180
Diagnosis of cystocele--the correlation between clinical and radiological evaluation.
Altman, Daniel; Mellgren, Anders; Kierkegaard, Jonas; Zetterström, Jan; Falconer, Christian; López, Annika
2004-01-01
In patients with genital prolapse involving several compartments simultaneously, radiologic investigation can be used to complement the clinical assessment. Contrast medium in the urinary bladder enables visualization of the bladder base at cystodefecoperitoneography (CDP). The aim of the present study was to evaluate the correlation between clinical examination using the Pelvic Organ Prolapse Quantification system (POP-Q) and CDP. Thirty-three women underwent clinical assessment and CDP. Statistical analysis using Pearson's correlation coefficient ( r) demonstrated a wide variability between the current definition of cystocele at CDP and POP-Q ( r=0.67). An attempt to provide an alternative definition of cystocele at CDP had a similar outcome ( r=0.63). The present study demonstrates a moderate correlation between clinical and radiologic findings in patients with anterior vaginal wall prolapse. It does not support the use of bladder contrast at radiologic investigation in the routine preoperative assessment of patients with genital prolapse. PMID:14752591
Quantum correlations from classically correlated states
NASA Astrophysics Data System (ADS)
Bellomo, G.; Majtey, A. P.; Plastino, A. R.; Plastino, A.
2014-07-01
Consider a bipartite quantum system with at least one of its two components being itself a composite system. By tracing over part of one (or both) of these two subsystems it is possible to obtain a reduced (separable) state that exhibits quantum correlations even if the original state of the full system is endowed only with classical correlations. This effect, first pointed out by Li and Luo in (2008), is of considerable interest because there is a growing body of evidence suggesting that quantum correlations in non-entangled, mixed states may constitute a useful resource to implement non trivial information related tasks. Here we conduct a systematic exploration of the aforementioned effect for particular families of states of quantum systems of low dimensionality (three qubits states). In order to assess the non-classicality of the correlations of the reduced states we use an indicator of quantum correlations based upon the state disturbances generated by the measurement of local observables. We show, for a three-qubit system, that there exists a relationship between the classical mutual information of the original classically correlated states and the maximum quantum correlation exhibited by the reduced states.
Correlation between p65 and TNF-? in patients with acute myelocytic leukemia
DONG, QIAO-MEI; LING, CHUN; ZHU, JUN-FANG; CHEN, XUAN; TANG, YAN; ZHAO, LI
2015-01-01
The correlation between the expression levels of p65 and TNF-? in patients with acute myelocytic leukemia (AML) and AML cell lines were investigated. The bone marrow samples of 30 AML patients and 10 non-leukemia controls were studied. The mRNA expression levels of p65 and TNF-? were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and Pearson's Correlation test was used to demonstrate the correlation between TNF-? and p65 expression levels in AML specimens. Receiver operating characteristic (ROC) curves were plotted to determine whether TNF-? and p65 expression levels could be used to differentiate AML samples from non-leukemia samples. MG132 and anti-TNF-? antibody were used to inhibit the expression of p65 and TNF-? in the AML cell line, HL-60. The expression of p65 and TNF-? were detected by RT-qPCR and western blot analysis. The mRNA expression levels of p65 and TNF-? were significantly increased in AML patients compared with non-leukemia control bone marrow samples by RT-qPCR, and the two molecules expression pattern's exhibited sufficient predictive power to distinguish AML patients from non-leukemia control samples. Pearson's correlation analysis demonstrated that TNF-? expression was strongly correlated with p65 expression in AML bone marrow samples. In HL-60 cells, inhibition of TNF-? reduced the expression of p65; in addition, inhibition of p65 reduced the expression of TNF-? as assessed by RT-qPCR and western blot analysis. p65 and TNF-? were highly expressed in AML patients, and these 2 molecules were strongly correlated. The present study indicates that p65 and TNF-? have potential as molecular markers to distinguish AML patients from non-leukemia control samples, and that these 2 molecules may be useful prognostic factor for patients with AML. PMID:26722330
Information-limiting correlations.
Moreno-Bote, Rubén; Beck, Jeffrey; Kanitscheider, Ingmar; Pitkow, Xaq; Latham, Peter; Pouget, Alexandre
2014-10-01
Computational strategies used by the brain strongly depend on the amount of information that can be stored in population activity, which in turn strongly depends on the pattern of noise correlations. In vivo, noise correlations tend to be positive and proportional to the similarity in tuning properties. Such correlations are thought to limit information, which has led to the suggestion that decorrelation increases information. In contrast, we found, analytically and numerically, that decorrelation does not imply an increase in information. Instead, the only information-limiting correlations are what we refer to as differential correlations: correlations proportional to the product of the derivatives of the tuning curves. Unfortunately, differential correlations are likely to be very small and buried under correlations that do not limit information, making them particularly difficult to detect. We found, however, that the effect of differential correlations on information can be detected with relatively simple decoders. PMID:25195105
Oninla, Olumayowa Abimbola
2014-01-01
Skin diseases are indicators of HIV/AIDS which correlates with WHO clinical stages. In resource limited environment where CD4 count is not readily available, they can be used in assessing HIV patients. The study aims to determine the mucocutaneous manifestations in HIV positive patients and their correlation with WHO clinical stages. A prospective cross-sectional study of mucocutaneous conditions was done among 215 newly diagnosed HIV patients from June 2008 to May 2012 at adult ART clinic, Wesley Guild Hospital Unit, OAU Teaching Hospitals Complex, Ilesha, Osun State, Nigeria. There were 156 dermatoses with oral/oesophageal/vaginal candidiasis (41.1%), PPE (24.4%), dermatophytic infections (8.9%), and herpes zoster (3.8%) as the most common dermatoses. The proportions of dermatoses were 4.5%, 21.8%, 53.2%, and 20.5% in stages 1–4, respectively. A significant relationship (using Pearson's Chi square with P value <0.05) was obtained between dermatoses and WHO clinical stages. Pearson's correlation coefficient showed a positive correlation between the number of dermatoses and the WHO clinical stages. Dermatoses can therefore serve as diagnostic and prognostic markers in resource limited settings to initiate HAART in clinical stages 3 and 4. PMID:25587439
Codes with special correlation.
NASA Technical Reports Server (NTRS)
Baumert, L. D.
1964-01-01
Uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets
NASA Technical Reports Server (NTRS)
Surkis, Igor; Ken, Voitsekh; Melnikov, Alexey; Mishin, Vladimir; Sokolova, Nadezda; Shantyr, Violet; Zimovsky, Vladimir
2013-01-01
The activities of the six-station IAA RAS correlator include regular processing of national geodetic VLBI programs Ru-E, Ru-U, and Ru-F. The Ru-U sessions have been transferred in e-VLBI mode and correlated in the IAA Correlator Center automatically since 2011. The DiFX software correlator is used at the IAA in some astrophysical experiments.
Correlation in business networks
NASA Astrophysics Data System (ADS)
Souma, Wataru; Aoyama, Hideaki; Fujiwara, Yoshi; Ikeda, Yuichi; Iyetomi, Hiroshi; Kaizoji, Taisei
2006-10-01
This paper considers business networks. Through empirical study, we show that business networks display characteristics of small-world networks and scale-free networks. In this paper, we characterize firms as sales and bankruptcy probabilities. A correlation between sales and a correlation between bankruptcy probabilities in business networks are also considered. The results reveal that the correlation between sales depends strongly on the type of network, whereas the correlation between bankruptcy probabilities does so only weakly.
Spatial correlations in multifractals
NASA Technical Reports Server (NTRS)
Cates, M. E.; Deutsch, J. M.
1987-01-01
Spatial correlations within multifractals or fractal measures are considered. It is shown how scaling dimensions can be used to predict scaling laws for spatial correlation functions. It is concluded that the overlaid singularity picture does not provide an adequate description of the spatial properties of multifractals, and that blob concepts seem to provide a much more suitable description of multifractal correlations.
Reverse Correlation in Neurophysiology
ERIC Educational Resources Information Center
Ringach, Dario; Shapley, Robert
2004-01-01
This article presents a review of reverse correlation in neurophysiology. We discuss the basis of reverse correlation in linear transducers and in spiking neurons. The application of reverse correlation to measure the receptive fields of visual neurons using white noise and m-sequences, and classical findings about spatial and color processing in…
NASA Technical Reports Server (NTRS)
Sekido, Mamoru; Takefuji, Kazuhiro
2013-01-01
Kashima Space Technology Center (KSTC) is making use of two kinds of software correlators, the multi-channel K5/VSSP software correlator and the fast wide-band correlator 'GICO3,' for geodetic and R&D VLBI experiments. Overview of the activity and future plans are described in this paper.
Underestimating Correlation from Scatterplots.
ERIC Educational Resources Information Center
Strahan, Robert F.; Hansen, Chris J.
1979-01-01
Eighty graduate students and faculty estimated the correlation coefficient for each of 13 computer-printed scatterplots. As predicted, subjects underestimated the degree of actual correlation. With substantial moderation by a method-of-presentation factor, this underestimation was most pronounced in the middle of the correlational range.â€¦
Is There Any Correlation Between Patient Height and Patellar Tendon Length?
Navali, Amir M; Jafarabadi, Mohammad Asghari
2015-01-01
Background: A potential specific problem of patellar tendon graft in ACL reconstruction is the possibility of graft-tunnel mismatch which could be more problematic with anatomic ACL reconstruction where the femoral tunnel is placed low on the lateral wall of the lateral femoral condyle. The occasional occurrence of this mismatch raises the question that whether a correlation exists between patient height and patellar tendon length. The purpose of the present study was to measure patellar tendon length as an anthropometric finding and to evaluate whether a correlation exists between patient height and patellar tendon length. Methods: Intra-operative measurement of patellar tendon length was carried out in 267 consecutive patients during bone-patellar tendon-bone (BTB) graft ACL reconstruction. Patient age, gender, height were recorded. The patellar tendon measurements were done independently by two surgeons and the possible inter-observer errors were checked. The data were analyzed using the Pearson correlation. Results: The mean length of the patellar tendon was 46.4 ± 4.8 mm (Mean ± SD) with a range of 32–61 mm. The mean patient height was 177 ± 7 cm (Mean ± SD) with a range of 159–197 cm. A weak positive correlations were found between patient height and patellar tendon length (Pearson r = 0.24, P< 0.001). The linear regression equation for patellar tendon length (y, in millimeters) as a function of patient height (x, in centimeters) can be expressed as y=16.54 + 0.17x. Conclusions: Our study showed a weak correlation between patellar tendon length and patient height. This finding is in contrast to the usual measurements in human anthropometry in which taller individuals have normally longer tendons and ligaments. The graft-tunnel mismatch may be the result of this variation. PMID:26110175
NASA Astrophysics Data System (ADS)
Skvortsova, Yulia; Wang, Gufeng; Geng, M. Lei
2006-11-01
Statistical correlation coefficient mapping has proven to be a useful technique in tissue classification for cancer diagnosis. The classification is achieved by comparing the correlation coefficients for an unknown to a set of selected tissue samples with known pathological conditions. Currently, the correlation coefficient threshold in the classification is empirically determined. In this paper, boundaries of statistical significance between different tissue pathological conditions are established through Bayesian analysis on the Fisher's z-transformed Pearson's correlation coefficients between tissue samples. Moreover, probability values are provided in assigning a tissue sample to a specific tissue clinical condition, which is more appreciable in clinical practices. The methodology is examined with a simulated tissue-phantom data set, yielding satisfactory diagnostic results.
NASA Astrophysics Data System (ADS)
Nelson, D. J.
2007-09-01
In the basic correlation process a sequence of time-lag-indexed correlation coefficients are computed as the inner or dot product of segments of two signals. The time-lag(s) for which the magnitude of the correlation coefficient sequence is maximized is the estimated relative time delay of the two signals. For discrete sampled signals, the delay estimated in this manner is quantized with the same relative accuracy as the clock used in sampling the signals. In addition, the correlation coefficients are real if the input signals are real. There have been many methods proposed to estimate signal delay to more accuracy than the sample interval of the digitizer clock, with some success. These methods include interpolation of the correlation coefficients, estimation of the signal delay from the group delay function, and beam forming techniques, such as the MUSIC algorithm. For spectral estimation, techniques based on phase differentiation have been popular, but these techniques have apparently not been applied to the correlation problem . We propose a phase based delay estimation method (PBDEM) based on the phase of the correlation function that provides a significant improvement of the accuracy of time delay estimation. In the process, the standard correlation function is first calculated. A time lag error function is then calculated from the correlation phase and is used to interpolate the correlation function. The signal delay is shown to be accurately estimated as the zero crossing of the correlation phase near the index of the peak correlation magnitude. This process is nearly as fast as the conventional correlation function on which it is based. For real valued signals, a simple modification is provided, which results in the same correlation accuracy as is obtained for complex valued signals.
Weyand, Sabine; Chau, Tom
2015-01-01
Brain–computer interfaces (BCIs) provide individuals with a means of interacting with a computer using only neural activity. To date, the majority of near-infrared spectroscopy (NIRS) BCIs have used prescribed tasks to achieve binary control. The goals of this study were to evaluate the possibility of using a personalized approach to establish control of a two-, three-, four-, and five-class NIRS–BCI, and to explore how various user characteristics correlate to accuracy. Ten able-bodied participants were recruited for five data collection sessions. Participants performed six mental tasks and a personalized approach was used to select each individual’s best discriminating subset of tasks. The average offline cross-validation accuracies achieved were 78, 61, 47, and 37% for the two-, three-, four-, and five-class problems, respectively. Most notably, all participants exceeded an accuracy of 70% for the two-class problem, and two participants exceeded an accuracy of 70% for the three-class problem. Additionally, accuracy was found to be strongly positively correlated (Pearson’s) with perceived ease of session (??=?0.653), ease of concentration (??=?0.634), and enjoyment (??=?0.550), but strongly negatively correlated with verbal IQ (??=??0.749). PMID:26483657
Balog, Judit; Thijssen, Peter E.; de Greef, Jessica C.; Shah, Bharati; van Engelen, Baziel G.M.; Yokomori, Kyoko; Tapscott, Stephen J.; Tawil, Rabi; van der Maarel, Silvčre M.
2012-01-01
The aim of our study was to identify relationships between epigenetic parameters correlating with a relaxed chromatin state of the DUX4 promoter region and clinical severity as measured by a clinical severity score or muscle pathologic changes in D4Z4 contraction-dependent (FSHD1) and –independent (FSHD2) facioscapulohumeral muscular dystrophy patients. Twenty primary fibroblast (5 control, 10 FSHD1 and 5 FSHD2) and 26 primary myoblast (9 control, 12 FSHD1 and 5 FSHD2) cultures originating from patients with FSHD and controls were analyzed. Histone modification levels were determined by chromatin immunoprecipitation. We examined correlations between the chromatin compaction score (ChCS) defined by the H3K9me3:H3K4me2 ratio and an age corrected clinical severity score (CSS) or muscle pathology score (MPS). Possible relationships were investigated using linear regression analysis and significance was tested by Pearson’s product-moment coefficient. We found a significant difference of the ChCS between controls and patients with FSHD1 and between controls and patients with FSHD2. Tissue specific differences in ChCS were also observed. We also found a near-significant relationship between ChCS and the age corrected CSS in fibroblasts but not in myoblasts. Surprisingly, we found a strong correlation between the MPS of the vastus lateralis and the CSS. Our results confirm the D4Z4 chromatin relaxation previously shown to be associated with FSHD in a small number of samples. A possible relationship between clinical and epigenetic parameters could be established in patient fibroblasts, but not in myoblasts. The strong correlation between the MPS of the vastus lateralis and the CSS suggests that this muscle can be used to study for surrogate markers of overall disease severity. PMID:22522912
Báez, Eileen A.; Shah, Shreepal; Felipe, Dania; Maynard, John; Chalew, Stuart
2014-01-01
Objective: The objective was to assess the relationship of skin advanced glycation endproducts (AGEs) between first-degree relatives estimated from skin fluorescence (SF) after adjustment for skin pigmentation. Study design: SF was excited by LEDs centered at 375, 405, and 420 nm from children with type 1 diabetes and their mothers. Data were adjusted to generate measures of skin intrinsic fluorescence (SIF) at the various excitation wavelengths, using 2 different pairs of correction coefficients for excitation (kx) and emission (km): kx = 0.5, km = 0.5 (not associated with skin pigmentation) and kx = 1.0, km = 0.0 (strongly associated with skin pigmentation). Pearson correlation analysis was performed, as well as a multiple variable analysis with maternal SIF adjusted for the effects of maternal age and race. Results: There were 50 matched pairs of children and their mothers. Children were 13.3 ± 3.7 years of age and there were 19 boys/31 girls and 15 black/35 white. Mothers were 41.8 ± 6.8 years of age. The age of mother and child was highly correlated, r = .64, P < .0001. In Pearson correlation analysis, child’s SIF (kx = 1.0, km = 0.0) the had strongest association with maternal SIF, while with SIF (kx = 0.5, km = 0.5) there was a trend for association. In the multiple variable model child SIF was associated with maternal SIF for all corrections and wavelengths but was stronger for kx = 1.0, km = 0.0. Conclusion: Even after adjustment for skin pigmentation and race, correlation of SIF between family members persists, suggesting that other genetic and/or environmental factors shared by parent and child may influence estimated skin AGEs. PMID:25411062
Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.
2016-01-01
Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123
NASA Technical Reports Server (NTRS)
Hewes, C. R.; Bosshart, P. W.; Eversole, W. L.; Dewit, M.; Buss, D. D.
1976-01-01
Two CCD techniques were discussed for performing an N-point sampled data correlation between an input signal and an electronically programmable reference function. The design and experimental performance of an implementation of the direct time correlator utilizing two analog CCDs and MOS multipliers on a single IC were evaluated. The performance of a CCD implementation of the chirp z transform was described, and the design of a new CCD integrated circuit for performing correlation by multiplication in the frequency domain was presented. This chip provides a discrete Fourier transform (DFT) or inverse DFT, multipliers, and complete support circuitry for the CCD CZT. The two correlation techniques are compared.
Local available quantum correlations
NASA Astrophysics Data System (ADS)
Mundarain, Douglas F.; de Guevara, María L. Ladrón
2015-12-01
In this work, local available quantum correlations are studied. They are defined in terms of mutual information of bipartite local measurements done over an optimal local basis complementary to the local basis which defines the respective classical correlations. For two qubits, it is always possible to choose the basis of classical correlations as the set of eigenvectors of ? _z (the third Pauli matrix) and complementary bases become the sets of eigenvectors of the observables orthogonal to ? _z. It is shown that all states with zero local available quantum correlations are separable but not necessarily strictly classical; this fact puts this kind of correlations in the middle between discord and entanglement. Since in many cases it may suffice to know whether a given state has quantum correlations, the structure of the states with zero local available quantum correlations is presented. It is also shown that there is a close connection between local available quantum correlations and the protocol of entanglement activation developed by Piani et al. (Phys Rev Lett 106:220403, 2011). If a state satisfies the sufficient condition for the entanglement swapping associated with this protocol, this state has nonzero local available quantum correlations.
Correlation between lidar-derived intensity and passive optical imagery
NASA Astrophysics Data System (ADS)
Metcalf, Jeremy P.; Kim, Angela M.; Kruse, Fred A.; Olsen, Richard C.
2014-06-01
When LiDAR data are collected, the intensity information is recorded for each return, and can be used to produce an image resembling those acquired by passive imaging sensors. This research evaluated LiDAR intensity data to determine its potential for use as baseline imagery where optical imagery are unavailable. Two airborne LiDAR datasets collected at different point densities and laser wavelengths were gridded and compared with optical imagery. Optech Orion C200 laser data were compared with a corresponding 1541 nm spectral band from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). Optech ALTM Gemini LiDAR data collected at 1064 nm were compared to the WorldView-2 (WV-2) 949 - 1043 nm NIR2 band. Intensity images were georegistered and spatially resampled to match the optical data. The Pearson Product Moment correlation coefficient was calculated between datasets to determine similarity. Comparison for the full LiDAR datasets yielded correlation coefficients of approximately 0.5. Because LiDAR returns from vegetation are known to be highly variable, a Normalized Difference Vegetation Index (NDVI) was calculated utilizing the optical imagery, and intensity and optical imagery were separated into vegetation and nonvegetation categories. Comparison of the LiDAR intensity for non-vegetated areas to the optical imagery yielded coefficients greater than 0.9. These results demonstrate that LiDAR intensity data may be useful in substituting for optical imagery where only LiDAR is available.
Statistical functions and relevant correlation coefficients of clearness index
NASA Astrophysics Data System (ADS)
Pavanello, Diego; Zaaiman, Willem; Colli, Alessandra; Heiser, John; Smith, Scott
2015-08-01
This article presents a statistical analysis of the sky conditions, during years from 2010 to 2012, for three different locations: the Joint Research Centre site in Ispra (Italy, European Solar Test Installation - ESTI laboratories), the site of National Renewable Energy Laboratory in Golden (Colorado, USA) and the site of Brookhaven National Laboratories in Upton (New York, USA). The key parameter is the clearness index kT, a dimensionless expression of the global irradiance impinging upon a horizontal surface at a given instant of time. In the first part, the sky conditions are characterized using daily averages, giving a general overview of the three sites. In the second part the analysis is performed using data sets with a short-term resolution of 1 sample per minute, demonstrating remarkable properties of the statistical distributions of the clearness index, reinforced by a proof using fuzzy logic methods. Successively some time-dependent correlations between different meteorological variables are presented in terms of Pearson and Spearman correlation coefficients, and introducing a new one.
Fuzzy correlation analysis with realization
NASA Astrophysics Data System (ADS)
Tang, Yue Y.; Fan, Xinrui; Zheng, Ying N.
1998-10-01
The fundamental concept of fuzzy correlation is briefly discussed. Based on the correlation coefficient of classic correlation, polarity correlation and fuzzy correlation, the relationship between the correlations are analyzed. A fuzzy correlation analysis has the merits of both rapidity and accuracy as some amplitude information of random signals has been utilized. It has broad prospects for application. The form of fuzzy correlative analyzer with NLX 112 fuzzy data correlator and single-chip microcomputer is introduced.
Correlates of Academic Procrastination.
ERIC Educational Resources Information Center
Milgram, Norman A.; And Others
1993-01-01
Investigated concurrent correlates of academic procrastination in Israeli college preparatory students (n=113). Procrastination in one course of study was found to be moderately correlated with procrastination in another but not to procrastination in routine tasks of daily living. Procrastination was weakly related to emotional upset about it and…
Explorations in Statistics: Correlation
ERIC Educational Resources Information Center
Curran-Everett, Douglas
2010-01-01
Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This sixth installment of "Explorations in Statistics" explores correlation, a familiar technique that estimates the magnitude of a straight-line relationship between two variables. Correlation is meaningful only when the…
Correlating Heart Rate and Perceived Exertion during Aerobic Exercise in Alzheimer’s Disease
Yu, Fang; Bil, Kristin
2010-01-01
Older adults reap many health benefits from aerobic exercise training; however, little is known about how to monitor training responses in older adults with Alzheimer’s disease. The purpose of this paper was to examine the correlation of objectively measured heart rate and subjectively reported perceived exertion during aerobic exercise training in four older men with advanced Alzheimer’s disease from a pilot study that used a one-group pre- and post-test design. During training (3 times a week for 8 weeks), participant’s heart rate and perceived exertion was assessed by a trained exercise trainer every 5 minutes using Polar™ heart rate monitor and the Borg Rating of Perceived Exertion Scale respectively. There were 596 heart rate-perceived exertion data pairs. The results show that Pearson’s r for heart rate and perceived exertion was .457, significant at .01, 2-tailed, controlling for age, education, exercise session, and cognition. We conclude that the Borg scale itself might be insufficient for monitoring exercise responses in older men with advanced Alzheimer’s disease. Future studies are needed to further examine the utility of the Borg scale in this population. PMID:20727090
HIV Prevalence Correlates with High-Risk Sexual Behavior in Ethiopia's Regions
Kenyon, Chris R.; Tsoumanis, Achilleas; Schwartz, Ilan Steven
2015-01-01
Background HIV prevalence varies between 0.9 and 6.5% in Ethiopia’s eleven regions. Little has been published examining the reasons for this variation. Methods We evaluated the relationship between HIV prevalence by region and a range of risk factors in the 2005 and 2011 Ethiopian Demographic Health Surveys. Pearson’s correlation was used to assess the relationship between HIV prevalence and each variable. Results There was a strong association between HIV prevalence and three markers of sexual risk: mean lifetime number of partners (men: r = 0.87; P < 0.001; women: r = 0.60; P = 0.05); reporting sex with a non-married, non-cohabiting partner (men: r = 0.92; P < 0.001, women r = 0.93; P < 0.001); and premarital sex. Condom usage and HIV testing were positively associated with HIV prevalence, while the prevalence of circumcision, polygamy, age at sexual debut and male migration were not associated with HIV prevalence. Conclusion Variation in sexual behavior may contribute to the large variations in HIV prevalence by region in Ethiopia. Population-level interventions to reduce risky sexual behavior in high HIV incidence regions should be considered. PMID:26496073
Correlation Identities and Application
NASA Astrophysics Data System (ADS)
Suzuki, Masuo
General correlation identities are derived in a unified way using the quantum analysis,1-4 which include the well-known classical correlation identities5-7 such as the Ising correlation identities.5,6 In particular, quantum correlation identities are applied to the Heisenberg models and the transverse Ising model with local constants of motion. Integral identities are also presented in the spirit of the Gauss-Manin connection and they are applied to derive the generalized Bernoulli equation on the pressure and energy of ideal quantum gasses. There are many applications to condensed matter physics, which will be summarized in the present article together with an integrated list of papers on such applications in order to show how useful these correlation identities are.
Strongly-correlated heterostructures
Okamoto, Satoshi
2012-01-01
Electronic phase behavior in correlated-electron systems is a fundamental problem of condensed matter physics. The change in the phase behavior near surfaces and interfaces, i.e., {\\em electronic reconstruction}, is therefore the fundamental issue of the correlated-electron surface or interface science. In addition to basic science, understanding of such a phase behavior is of crucial importance for potential devices exploiting the novel properties of the correlated systems. In this article, we present a general overview of the field, and then discuss the recent theoretical progress mainly focusing on the correlation effects. We illustrate the general concept of {\\em electronic reconstruction} by studying model heterostructures consisting of strongly-correlated systems. Future directions for research are also discussed.
Nonclassicality of Temporal Correlations
NASA Astrophysics Data System (ADS)
Brierley, Stephen; Kosowski, Adrian; Markiewicz, Marcin; Paterek, Tomasz; Przysie?na, Anna
2015-09-01
The results of spacelike separated measurements are independent of distant measurement settings, a property one might call two-way no-signaling. In contrast, timelike separated measurements are only one-way no-signaling since the past is independent of the future but not vice versa. For this reason some temporal correlations that are formally identical to nonclassical spatial correlations can still be modeled classically. We propose a new formulation of Bell's theorem for temporal correlations; namely, we define nonclassical temporal correlations as the ones which cannot be simulated by propagating in time the classical information content of a quantum system given by the Holevo bound. We first show that temporal correlations between results of any projective quantum measurements on a qubit can be simulated classically. Then we present a sequence of general measurements on a single m -level quantum system that cannot be explained by propagating in time an m -level classical system and using classical computers with unlimited memory.
Apochromatic optical correlation.
Pe'er, A; Wang, D; Lohmann, A W; Friesem, A A
2000-06-01
Optical correlation, or matched filtering, can now be applied more widely than before, because the light is now allowed to be totally incoherent, spatially and spectrally. Two such correlators were demonstrated recently. Their state of chromatic correction can be called achromatic, since the scaling error has two zero crossings within the visible range of wavelengths. We present a new apochromatic correlator, in which the scaling error has three zero crossings. The maximum error and the rms error are reduced by a factor of 5. Our apochromatic correlator is composed of two highly dispersive heavy flint lenses that are in contact with two diffractive lenses and two chromatic corrected refractive lenses. The uncommon combination of flint dispersion and diffractive dispersion enabled us to achieve apochromatic correction of the scaling factor of the correlator. PMID:18064180
Correlation of Space Shuttle Landing Performance with Post-Flight Cardiovascular Dysfunction
NASA Technical Reports Server (NTRS)
McCluskey, R.
2004-01-01
Introduction: Microgravity induces cardiovascular adaptations resulting in orthostatic intolerance on re-exposure to normal gravity. Orthostasis could interfere with performance of complex tasks during the re-entry phase of Shuttle landings. This study correlated measures of Shuttle landing performance with post-flight indicators of orthostatic intolerance. Methods: Relevant Shuttle landing performance parameters routinely recorded at touchdown by NASA included downrange and crossrange distances, airspeed, and vertical speed. Measures of cardiovascular changes were calculated from operational stand tests performed in the immediate post-flight period on mission commanders from STS-41 to STS-66. Stand test data analyzed included maximum standing heart rate, mean increase in maximum heart rate, minimum standing systolic blood pressure, and mean decrease in standing systolic blood pressure. Pearson correlation coefficients were calculated with the null hypothesis that there was no statistically significant linear correlation between stand test results and Shuttle landing performance. A correlation coefficient? 0.5 with a p<0.05 was considered significant. Results: There were no significant linear correlations between landing performance and measures of post-flight cardiovascular dysfunction. Discussion: There was no evidence that post-flight cardiovascular stand test data correlated with Shuttle landing performance. This implies that variations in landing performance were not due to space flight-induced orthostatic intolerance.
Bounded-observation Kalman filtering of correlation in multivariate neural recordings.
Mehdi Kafashan, Mohammad; Palanca, Ben J; Ching, ShiNung
2014-01-01
A persistent question in multivariate neural signal processing is how best to characterize the statistical association between brain regions known as functional connectivity. Of the many metrics available for determining such association, the standard Pearson correlation coefficient (i.e., the zero-lag cross-correlation) remains widely used, particularly in neuroimaging. Generally, the cross-correlation is computed over an entire trial or recording session, with the assumption of within-trial stationarity. Increasingly, however, the length and complexity of neural data requires characterizing transient effects and/or non-stationarity in the temporal evolution of the correlation. That is, to estimate dynamics in the association between brain regions. Here, we present a simple, data-driven Kalman filter-based approach to tracking correlation dynamics. The filter explicitly accounts for the bounded nature of correlation measurements through the inclusion of a Fisher transform in the measurement equation. An output linearization facilitates a straightforward implementation of the standard recursive filter equations, including admittance of covariance identification via an autoregressive least squares method. We demonstrate the efficacy and utility of the approach in an example of multivariate neural functional magnetic resonance imaging data. PMID:25571128
Ebadifard Azar, Farbod; Sarabi Asiabar, Ali
2015-01-01
Background: Effective leadership is essential to passing through obstacles facing the health field.The current health care system in Iran has major problems and gaps in the field of effective leadership. The aim of this study was to evaluate hospital managersâ€™ leadership style through selfassessment and to determine the correlation between leadership styles with healthcare executivesâ€™ leadership readiness and leadership effectiveness. Methods: In this cross-sectional study a self-administered questionnaire completed by all internal healthcare executives of all teaching and non-teaching hospitals affiliated to Iran University of Medical Sciences. Questionnaire was composed to determine demographic information, leadership style questions, leadership effectiveness and leadership readiness. Descriptive statistics and Pearson correlation coefficient were used for data analysis. Results: According to the findings, the dominant style of healthcare executives was transformational leadership style (with a score of 4.34). The leadership effectiveness was estimated at about 4.36 that shows the appropriate level of leadership effectiveness. There was a significant correlation (correlation coefficient of 0.244) between leadership readiness and transformational leadership style (p<0.05). Also, there was a significant correlation between leadership effectiveness with transformational (0.051) and transactional (0.216) styles. Conclusion: There was a correlation between leadership readiness and leadership effectiveness with leadership styles. Application of this research will be crucial to universities and healthcare executives. This study suggests that strengthening the scientific basis is essential for leadership readiness and leadership effectiveness in healthcare system. PMID:26000260
Geographically correlated orbit error
NASA Technical Reports Server (NTRS)
Rosborough, G. W.
1989-01-01
The dominant error source in estimating the orbital position of a satellite from ground based tracking data is the modeling of the Earth's gravity field. The resulting orbit error due to gravity field model errors are predominantly long wavelength in nature. This results in an orbit error signature that is strongly correlated over distances on the size of ocean basins. Anderle and Hoskin (1977) have shown that the orbit error along a given ground track also is correlated to some degree with the orbit error along adjacent ground tracks. This cross track correlation is verified here and is found to be significant out to nearly 1000 kilometers in the case of TOPEX/POSEIDON when using the GEM-T1 gravity model. Finally, it was determined that even the orbit error at points where ascending and descending ground traces cross is somewhat correlated. The implication of these various correlations is that the orbit error due to gravity error is geographically correlated. Such correlations have direct implications when using altimetry to recover oceanographic signals.
Interaural correlation sensitivity.
Culling, J F; Colburn, H S; Spurchise, M
2001-08-01
Sensitivity to differences in interaural correlation was measured for 1.3-ERB-wide bands of noise using a 2IFC task at six frequencies: 250, 500, 750, 1000, 1250, and 1500 Hz. The sensitivity index, d', was measured for discriminations between a number of fixed pairs of correlation values. Cumulative d' functions were derived for each frequency and condition. The d' for discriminating any two values of correlation may be recovered from the cumulative d' function by the difference between cumulative d''s for these values. Two conditions were employed: the noisebands were either presented in isolation (narrow-band condition) or in the context of broad, contiguous flanking bands of correlated noise (fringed condition). The cumulative d' functions showed greater sensitivity to differences in correlation close to 1 than close to 0 at low frequencies, but this difference was less pronounced in the fringed condition. Also, a more linear relationship was observed when cumulative d' was plotted as a function of the equivalent signal-to-noise ratio (SNR) in dB for each correlation value, rather than directly against correlation. The equivalent SNR was the SNR at which the interaural correlation in an NoS(pi) stimulus would equal the interaural correlation of the noise used in the experiment. The maximum cumulative d' declined above 750 Hz. This decline was steeper for the fringed than for the narrow-band condition. For the narrow-band condition, the total cumulative d' was variable across listeners. All cumulative d' functions were closely fitted using a simple two-parameter function. The complete data sets, averaged across listeners, from the fringed and narrow-band conditions were fitted using functions to describe the changes in these parameters over frequency, in order to produce an interpolated family of curves that describe sensitivity at frequencies between those tested. These curves predict the spectra recovered by the binaural system when complex sounds, such as speech, are masked by noise. PMID:11519570
Hadronic Correlations and Fluctuations
Koch, Volker
2008-10-09
We will provide a review of some of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. We will discuss Lattice QCD results on fluctuations and correlations and will put them into context with observables which have been measured in heavy-ion collisions. Special attention will be given to the QCD critical point and the first order co-existence region, and we will discuss how the measurement of fluctuations and correlations can help in an experimental search for non-trivial structures in the QCD phase diagram.
Haystack Observatory VLBI Correlator
NASA Technical Reports Server (NTRS)
Titus, Mike; Cappallo, Roger; Corey, Brian; Dudevoir, Kevin; Niell, Arthur; Whitney, Alan
2013-01-01
This report summarizes the activities of the Haystack Correlator during 2012. Highlights include finding a solution to the DiFX InfiniBand timeout problem and other DiFX software development, conducting a DBE comparison test following the First International VLBI Technology Workshop, conducting a Mark IV and DiFX correlator comparison, more broadband delay experiments, more u- VLBI Galactic Center observations, and conversion of RDV session processing to the Mark IV/HOPS path. Non-real-time e-VLBI transfers and engineering support of other correlators continued.
Nosrati, R; Owlia, P; Saderi, H; Olamaee, M; Rasooli, I; Akhavian, Tehrani A
2012-01-01
Background and Objectives Azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gram-negative soil bacterium capable of fixing nitrogen. Oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of A. vinelandii cultivation. This phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. The aim of this study was to design a simple strategy to explain the alginate production, cell growth and nitrogenase activity correlation in A. vinelandii under aerobic conditions. Material and Methods Thirty-five different soil samples were taken from the rhizosphere of agricultural crops of Iran. Enrichment and isolation strategies were employed for microbial isolation. Physiological and biochemical characteristics were determined. Molecular identification was performed using selective nifH-g1 primers. Alginate production and nitrogenase activity assay by each isolate of Azotobacter were carried out. Bacterial growth, alginate production and Nitrogenase activity were conducted by time-coursed quantitative measurements. Results Total of 26 isolates were selected after enrichment, isolation, and screening. The isolate was identified by molecular tests as A. vinelandii. The highest alginate productions of 1.02 g/l and 0.91g/l were noted after 4 days in 8 isolates, cell biomass of which were estimated 4.88-5.26 g/l. Six of 8 isolates were able to fix atmospheric N2 on nitrogen-free medium. Rates obtained in isolates were in the range of 12.1 to 326.4 nmol C2H4 h-1 vial-1. Conclusions Nitrogen fixation and alginate production yielded significant and positive Pearson's correlation coefficient of R2 = 0.760, p ? 0.02. Finally association between bacterial growth, alginate production and nitrogenase activity almost noticeable yielded significant and positive Pearson's correlation coefficient R2= 0.723, p ? 0.04. PMID:23066492
Correlating laser damage tests.
Arenberg, J W; Frink, M E; Mordaunt, D W; Lee, G; Seitel, S C; Teppo, E A
1989-01-01
This paper reports on efforts to correlate two commercially oriented laser damage tests. The two test facilities are located at Hughes Aircraft Co. and Montana Laser Optics*. A variety of coated laser optics have been tested in different test conditions and the damage levels compared. The test parameters varied were transverse modal content, spot size, sample conditioning history and, to a lesser degree, pulse width. The accumulated results were correlated by ascertaining the existence of a high probability functional relationship (linear fit) between pairs of damage levels for the same optics in different test conditions. A strong correlation was found between samples tested with the same irradiance history, regardless of the modal content and pulse width. Comparisons of the samples of different irradiance conditioning history were found not to correlate in general. PMID:20548437
Angelsky, Oleg V; Gbur, Gregory J; Polyanskii, Peter; Hanson, Steen G; Volyar, Alexander; Zimnyakov, Dmitry A; Mokhun, Igor
2012-04-01
This feature issue of Applied Optics contains a series of selected papers reflecting the state-of-the-art of correlation optics and showing synergetics between the theoretical background and experimental techniques. PMID:22505120
Extractable Work from Correlations
NASA Astrophysics Data System (ADS)
Perarnau-Llobet, Martí; Hovhannisyan, Karen V.; Huber, Marcus; Skrzypczyk, Paul; Brunner, Nicolas; Acín, Antonio
2015-10-01
Work and quantum correlations are two fundamental resources in thermodynamics and quantum information theory. In this work, we study how to use correlations among quantum systems to optimally store work. We analyze this question for isolated quantum ensembles, where the work can be naturally divided into two contributions: a local contribution from each system and a global contribution originating from correlations among systems. We focus on the latter and consider quantum systems that are locally thermal, thus from which any extractable work can only come from correlations. We compute the maximum extractable work for general entangled states, separable states, and states with fixed entropy. Our results show that while entanglement gives an advantage for small quantum ensembles, this gain vanishes for a large number of systems.
NASA Astrophysics Data System (ADS)
Gregory, Don A.; Kirsch, James C.
1989-02-01
In the past 15 years, a dozen or so designs have been proposed for compact optical correlators. Of these, maybe one-third of them have actually been built and only a few of those tested. This paper will give an overview of some of the systems that have been built as well as mention some promising early and current designs that have not been built. The term compact, as used in the title of this paper, will be applied very loosely; to mean smaller than a laboratory size optical table. To date, only one correlator has been built and tested that actually can be called miniature. This softball size correlator was built by the Perkin-Elmer Corporation for the U. S. Army Missile Command at Redstone Arsenal, Alabama. More will be said about this correlator in following sections.
Ozone Correlative Measurements Workshop
NASA Technical Reports Server (NTRS)
Hilsenrath, E. (editor)
1985-01-01
A study was conducted to determine the necessary parameters for the correlation of data on Earth ozone. Topics considered were: (1) measurement accuracy; (2) equipment considerations (SBUV); and (3) ground based measurements to support satellite data.
Correlations and droplet growth
NASA Technical Reports Server (NTRS)
Marder, M.
1985-01-01
Consideration is given to the time development of a system in which small spheres of a stable phase grow out of a supersaturated melt. The spheres then grow and shrink in a manner similar to Ostwald ripening. The growth process of pairs of particles in an effective background accounts for can be used to explain the long time correlations which develop in the system. The correlations broaden the distribution of particles sizes, even for relatively dilute systems.
NASA Technical Reports Server (NTRS)
Kurihara, Shinobu; Nozawa, Kentaro
2013-01-01
The K5/VSSP software correlator (Figure 1), located in Tsukuba, Japan, is operated by the Geospatial Information Authority of Japan (GSI). It is fully dedicated to processing the geodetic VLBI sessions of the International VLBI Service for Geodesy and Astrometry. All of the weekend IVS Intensives (INT2) and the Japanese domestic VLBI observations organized by GSI were processed at the Tsukuba VLBI Correlator.
Electronic correlations in manganites
Held; Vollhardt
2000-05-29
The influence of local electronic correlations on the properties of colossal magnetoresistive manganites is investigated. To this end, a ferromagnetic two-band Kondo lattice model is supplemented with the local Coulomb repulsion missing in this model and is analyzed within dynamical mean-field theory. Results for the spectral function, optical conductivity, and the paramagnetic-to-ferromagnetic phase transition show that electronic correlations have drastic effects and may explain some experimental observations. PMID:10990894
Ramot, D; Milo, R; Friedman, M; Kandel, A
2001-01-01
A general framework for dealing with numerical measurements in an approximate, uncertain, or fuzzy environment is presented. A fuzzy measurement is defined. It possesses several unique properties, which arise from its physical nature and distinguish it from concepts such as the fuzzy number. These properties, which include the fuzzy correlation term and the fuzzy Equality relation, follow directly from physical considerations. The introduction of the fuzzy correlation term provides a mathematical tool for representing any correlation relations, which may exist between different fuzzy measurements. The main function of the fuzzy correlation term is to eliminate, or filter out, measurement values that are unlikely, given other fuzzy measurements. Thus, using the fuzzy correlation term, the range of possible measurement values is limited by physical realities. The information represented by the fuzzy correlation term is shown to be of great value in providing a wider picture of reality than it is possible to obtain by simply considering individual fuzzy measurements. Arithmetic operations on fuzzy measurements and functions of fuzzy measurements are also discussed, leading to the derivation of the fuzzy Riemann integral and its applications. PMID:18244801
NASA Astrophysics Data System (ADS)
Escoffier, R. P.; Comoretto, G.; Webber, J. C.; Baudry, A.; Broadwell, C. M.; Greenberg, J. H.; Treacy, R. R.; Cais, P.; Quertier, B.; Camino, P.; Bos, A.; Gunst, A. W.
2007-02-01
Aims: The Atacama Large Millimeter Array (ALMA) is an international astronomy facility to be used for detecting and imaging all types of astronomical sources at millimeter and submillimeter wavelengths at a 5000-m elevation site in the Atacama Desert of Chile. Our main aims are: describe the correlator sub-system which is that part of the ALMA system that combines the signal from up to 64 remote individual radio antennas and forms them into a single instrument; emphasize the high spectral resolution and the configuration flexibility available with the ALMA correlator. Methods: The main digital signal processing features and a block diagram of the correlator being constructed for the ALMA radio astronomy observatory are presented. Tables of observing modes and spectral resolutions offered by the correlator system are given together with some examples of multi-resolution spectral modes. Results: The correlator is delivered by quadrants and the first quadrant is being tested while most of the other printed circuit cards required by the system have been produced. In its final version the ALMA correlator will process the outputs of up to 64 antennas using an instantaneous bandwidth of 8 GHz in each of two polarizations per antenna. In the frequency division mode, unrivalled spectral flexibility together with very high resolution (3.8 kHz) and up to 8192 spectral points are achieved. In the time division mode high time resolution is available with minimum data dump rates of 16 ms for all cross-products.
Kim, Dahan; Curthoys, Nikki M.; Parent, Matthew T.; Hess, Samuel T.
2015-01-01
Multi-colour localization microscopy has enabled sub-diffraction studies of colocalization between multiple biological species and quantification of their correlation at length scales previously inaccessible with conventional fluorescence microscopy. However, bleed-through, or misidentification of probe species, creates false colocalization and artificially increases certain types of correlation between two imaged species, affecting the reliability of information provided by colocalization and quantified correlation. Despite the potential risk of these artefacts of bleed-through, neither the effect of bleed-through on correlation nor methods of its correction in correlation analyses has been systematically studied at typical rates of bleed-through reported to affect multi-colour imaging. Here, we present a reliable method of bleed-through correction applicable to image rendering and correlation analysis of multi-colour localization microscopy. Application of our bleed-through correction shows our method accurately corrects the artificial increase in both types of correlations studied (Pearson coefficient and pair correlation), at all rates of bleed-through tested, in all types of correlations examined. In particular, anti-correlation could not be quantified without our bleed-through correction, even at rates of bleed-through as low as 2%. Demonstrated with dichroic-based multi-colour FPALM here, our presented method of bleed-through correction can be applied to all types of localization microscopy (PALM, STORM, dSTORM, GSDIM, etc.), including both simultaneous and sequential multi-colour modalities, provided the rate of bleed-through can be reliably determined. PMID:26185614
(Dis)similarity Index To Compare Correlated Motions in Molecular Simulations.
Tiberti, Matteo; Invernizzi, Gaetano; Papaleo, Elena
2015-09-01
Molecular dynamics (MD) simulations are widely used to complement or guide experimental studies in the characterization of protein dynamics, thanks to improvements in force-field accuracy, along with in the software and hardware to sample the conformational landscape of proteins. Among the different applications of MD simulations, the study of correlated motions is largely employed for different purposes. Several metrics have been developed to describe correlated motions in the MD ensemble, such as methods based on Pearson Correlation or Mutual Information. Cross-correlation analysis of MD trajectories is indeed appealing not only to identify residues characterized by coupled fluctuations in protein structures but also since it can be used to extrapolate motions along directions in which major conformational changes should occur, for example on longer time scales than the ones that are actually simulated. Nevertheless, most of the MD studies employ average correlation maps and mostly in a qualitative way, even when different systems or different replicates of the same system are compared. The broad application of correlation metrics in the analysis of MD simulations, especially for comparative purposes, requires a step forward toward more quantitative and accurate comparisons. We thus here employed a simple but effective index, which is based on a normalized Frobenius norm of the differences between protein correlation maps, to compare correlated motions. We applied this index for a quantitative comparison of correlated motions from MD simulations of seven proteins of different size and fold. We also employed the index to assess the robustness of correlation description when multi-replicate MD simulations of a same system are used, and we compared our index to metrics for comparison of structural ensembles such as Root Mean Square Inner Product and the Bhattacharyya Coefficient. PMID:26575932
Dawson, Debra Ann; Lam, Jack; Lewis, Lindsay B; Carbonell, Felix; Mendola, Janine D; Shmuel, Amir
2016-02-01
Numerous studies have demonstrated functional magnetic resonance imaging (fMRI)-based resting-state functional connectivity (RSFC) between cortical areas. Recent evidence suggests that synchronous fluctuations in blood oxygenation level-dependent fMRI reflect functional organization at a scale finer than that of visual areas. In this study, we investigated whether RSFCs within and between lower visual areas are retinotopically organized and whether retinotopically organized RSFC merely reflects cortical distance. Subjects underwent retinotopic mapping and separately resting-state fMRI. Visual areas V1, V2, and V3, were subdivided into regions of interest (ROIs) according to quadrants and visual field eccentricity. Functional connectivity (FC) was computed based on Pearson's linear correlation (correlation), and Pearson's linear partial correlation (correlation between two time courses after the time courses from all other regions in the network are regressed out). Within a quadrant, within visual areas, all correlation and nearly all partial correlation FC measures showed statistical significance. Consistently in V1, V2, and to a lesser extent in V3, correlation decreased with increasing eccentricity separation. Consistent with previously reported monkey anatomical connectivity, correlation/partial correlation values between regions from adjacent areas (V1-V2 and V2-V3) were higher than those between nonadjacent areas (V1-V3). Within a quadrant, partial correlation showed consistent significance between regions from two different areas with the same or adjacent eccentricities. Pairs of ROIs with similar eccentricity showed higher correlation/partial correlation than pairs distant in eccentricity. Between dorsal and ventral quadrants, partial correlation between common and adjacent eccentricity regions within a visual area showed statistical significance; this extended to more distant eccentricity regions in V1. Within and between quadrants, correlation decreased approximately linearly with increasing distances separating the tested ROIs. Partial correlation showed a more complex dependence on cortical distance: it decreased exponentially with increasing distance within a quadrant, but was best fit by a quadratic function between quadrants. We conclude that RSFCs within and between lower visual areas are retinotopically organized. Correlation-based FC is nonselectively high across lower visual areas, even between regions that do not share direct anatomical connections. The mechanisms likely involve network effects caused by the dense anatomical connectivity within this network and projections from higher visual areas. FC based on partial correlation, which minimizes network effects, follows expectations based on direct anatomical connections in the monkey visual cortex better than correlation. Last, partial correlation-based retinotopically organized RSFC reflects more than cortical distance effects. PMID:26415043
Nonclassicality of Temporal Correlations.
Brierley, Stephen; Kosowski, Adrian; Markiewicz, Marcin; Paterek, Tomasz; Przysi??na, Anna
2015-09-18
The results of spacelike separated measurements are independent of distant measurement settings, a property one might call two-way no-signaling. In contrast, timelike separated measurements are only one-way no-signaling since the past is independent of the future but not vice versa. For this reason some temporal correlations that are formally identical to nonclassical spatial correlations can still be modeled classically. We propose a new formulation of Bell's theorem for temporal correlations; namely, we define nonclassical temporal correlations as the ones which cannot be simulated by propagating in time the classical information content of a quantum system given by the Holevo bound. We first show that temporal correlations between results of any projective quantum measurements on a qubit can be simulated classically. Then we present a sequence of general measurements on a single m-level quantum system that cannot be explained by propagating in time an m-level classical system and using classical computers with unlimited memory. PMID:26430975
2012-01-01
Background Bioinformatics and high-throughput technologies such as microarray studies allow the measure of the expression levels of large numbers of genes simultaneously, thus helping us to understand the molecular mechanisms of various biological processes in a cell. Findings We calculate the Pearson Correlation Coefficient (r-value) between probe set signal values from Affymetrix Human Genome Microarray samples and cluster the human genes according to the r-value correlation matrix using the Neighbour Joining (NJ) clustering method. A hyper-geometric distribution is applied on the text annotations of the probe sets to quantify the term overrepresentations. The aim of the tool is the identification of closely correlated genes for a given gene of interest and/or the prediction of its biological function, which is based on the annotations of the respective gene cluster. Conclusion Human Gene Correlation Analysis (HGCA) is a tool to classify human genes according to their coexpression levels and to identify overrepresented annotation terms in correlated gene groups. It is available at: http://biobank-informatics.bioacademy.gr/coexpression/. PMID:22672625
Advanced quantum noise correlations
NASA Astrophysics Data System (ADS)
Vogl, Ulrich; Glasser, Ryan T.; Clark, Jeremy B.; Glorieux, Quentin; Li, Tian; Corzo, Neil V.; Lett, Paul D.
2014-01-01
We use the quantum correlations of twin beams of light to investigate the fundamental addition of noise when one of the beams propagates through a fast-light medium based on phase-insensitive gain. The experiment is based on two successive four-wave mixing processes in rubidium vapor, which allow for the generation of bright two-mode-squeezed twin beams followed by a controlled advancement while maintaining the shared quantum correlations between the beams. The demonstrated effect allows the study of irreversible decoherence in a medium exhibiting anomalous dispersion, and for the first time shows the advancement of a bright nonclassical state of light. The advancement and corresponding degradation of the quantum correlations are found to be operating near the fundamental quantum limit imposed by using a phase-insensitive amplifier.
Neuroanatomical Correlates of Intelligence
Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.
2009-01-01
With the advancement of image acquisition and analysis methods in recent decades, unique opportunities have emerged to study the neuroanatomical correlates of intelligence. Traditional approaches examining global measures have been complemented by insights from more regional analyses based on pre-defined areas. Newer state-of-the-art approaches have further enhanced our ability to localize the presence of correlations between cerebral characteristics and intelligence with high anatomic precision. These in vivo assessments have confirmed mainly positive correlations, suggesting that optimally increased brain regions are associated with better cognitive performance. Findings further suggest that the models proposed to explain the anatomical substrates of intelligence should address contributions from not only (pre)frontal regions, but also widely distributed networks throughout the whole brain. PMID:20160919
Correlation ion mobility spectroscopy
Pfeifer, Kent B. (Los Lunas, NM); Rohde, Steven B. (Corrales, NM)
2008-08-26
Correlation ion mobility spectrometry (CIMS) uses gating modulation and correlation signal processing to improve IMS instrument performance. Closely spaced ion peaks can be resolved by adding discriminating codes to the gate and matched filtering for the received ion current signal, thereby improving sensitivity and resolution of an ion mobility spectrometer. CIMS can be used to improve the signal-to-noise ratio even for transient chemical samples. CIMS is especially advantageous for small geometry IMS drift tubes that can otherwise have poor resolution due to their small size.
Correlation mapping microscopy
NASA Astrophysics Data System (ADS)
McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh M.; Leahy, Martin J.
2015-03-01
Changes in the microcirculation are associated with conditions such as Raynauds disease. Current modalities used to assess the microcirculation such as nailfold capillaroscopy are limited due to their depth ambiguity. A correlation mapping technique was recently developed to extend the capabilities of Optical Coherence Tomography to generate depth resolved images of the microcirculation. Here we present the extension of this technique to microscopy modalities, including confocal microscopy. It is shown that this correlation mapping microscopy technique can extend the capabilities of conventional microscopy to enable mapping of vascular networks in vivo with high spatial resolution.
Detrended fluctuation analysis made flexible to detect range of cross-correlated fluctuations.
KwapieĹ„, JarosĹ‚aw; OĹ›wiÄ™cimka, PaweĹ‚; DroĹĽdĹĽ, StanisĹ‚aw
2015-11-01
The detrended cross-correlation coefficient Ď_{DCCA} has recently been proposed to quantify the strength of cross-correlations on different temporal scales in bivariate, nonstationary time series. It is based on the detrended cross-correlation and detrended fluctuation analyses (DCCA and DFA, respectively) and can be viewed as an analog of the Pearson coefficient in the case of the fluctuation analysis. The coefficient Ď_{DCCA} works well in many practical situations but by construction its applicability is limited to detection of whether two signals are generally cross-correlated, without the possibility to obtain information on the amplitude of fluctuations that are responsible for those cross-correlations. In order to introduce some related flexibility, here we propose an extension of Ď_{DCCA} that exploits the multifractal versions of DFA and DCCA: multifractal detrended fluctuation analysis and multifractal detrended cross-correlation analysis, respectively. The resulting new coefficient Ď_{q} not only is able to quantify the strength of correlations but also allows one to identify the range of detrended fluctuation amplitudes that are correlated in two signals under study. We show how the coefficient Ď_{q} works in practical situations by applying it to stochastic time series representing processes with long memory: autoregressive and multiplicative ones. Such processes are often used to model signals recorded from complex systems and complex physical phenomena like turbulence, so we are convinced that this new measure can successfully be applied in time-series analysis. In particular, we present an example of such application to highly complex empirical data from financial markets. The present formulation can straightforwardly be extended to multivariate data in terms of the q-dependent counterpart of the correlation matrices and then to the network representation. PMID:26651752
Spatial and time correlation of thermometers and pluviometers in a weather network database
NASA Astrophysics Data System (ADS)
Tardivo, Gianmarco
2015-04-01
A basic issue that arises when analysing data bases from weather networks is the correlation system that characterizes the set of weather stations. Some statistical models being used for simulating temperature and precipitation or estimating missing data often exploit the Pearson's correlation coefficient, whereby a selection of predictors is carried out. In this paper, a specific analysis was made to understand the relationship between the distances (between the stations) and the correlation structure (of the network) and to assess the evolution of the stations ranking over the time from the network establishment, given that they were ranked on the basis of their correlation coefficient values with a target station. This study was first carried out over the whole of the Veneto region in Northeast Italy, and subsequently, it was repeated, subdividing the area into three main climatic zones: mountain, plain and coast. The variables that are involved in this study are the following: daily precipitation and daily maximum, mean and minimum temperature. Generally, the correlation coefficients of the database of precipitation are, on average, inversely proportional to the mean distances from the target station. Considering that the same behaviour was not detected on analysing the temperature database, the main results of this work can be summarized as follows: (1) the most correlated stations of precipitation are generally closer to a target station than the most correlated stations of temperature (entire area); (2) starting from 5.5 years after the network was established, the temperature variable is characterized by a high stability (over time) of the correlation rankings, up to a wide radius from the target station; (3) this trend is not so clear in precipitation data. However, when taking into account the first result, (4) generally, the most correlated stations are placed within the radius of stability, more frequently so for precipitation than for temperature.
Detrended fluctuation analysis made flexible to detect range of cross-correlated fluctuations
NASA Astrophysics Data System (ADS)
KwapieĹ„, JarosĹ‚aw; OĹ›wiecimka, PaweĹ‚; DroĹ»dĹ», StanisĹ‚aw
2015-11-01
The detrended cross-correlation coefficient ĎDCCA has recently been proposed to quantify the strength of cross-correlations on different temporal scales in bivariate, nonstationary time series. It is based on the detrended cross-correlation and detrended fluctuation analyses (DCCA and DFA, respectively) and can be viewed as an analog of the Pearson coefficient in the case of the fluctuation analysis. The coefficient ĎDCCA works well in many practical situations but by construction its applicability is limited to detection of whether two signals are generally cross-correlated, without the possibility to obtain information on the amplitude of fluctuations that are responsible for those cross-correlations. In order to introduce some related flexibility, here we propose an extension of ĎDCCA that exploits the multifractal versions of DFA and DCCA: multifractal detrended fluctuation analysis and multifractal detrended cross-correlation analysis, respectively. The resulting new coefficient Ďq not only is able to quantify the strength of correlations but also allows one to identify the range of detrended fluctuation amplitudes that are correlated in two signals under study. We show how the coefficient Ďq works in practical situations by applying it to stochastic time series representing processes with long memory: autoregressive and multiplicative ones. Such processes are often used to model signals recorded from complex systems and complex physical phenomena like turbulence, so we are convinced that this new measure can successfully be applied in time-series analysis. In particular, we present an example of such application to highly complex empirical data from financial markets. The present formulation can straightforwardly be extended to multivariate data in terms of the q -dependent counterpart of the correlation matrices and then to the network representation.
NASA Astrophysics Data System (ADS)
Moore, C. S.; Wood, T. J.; Saunderson, J. R.; Beavis, A. W.
2015-12-01
This work assessed the appropriateness of the signal-to-noise ratio improvement factor (KSNR) as a metric for the optimisation of computed radiography (CR) of the chest. The results of a previous study in which four experienced image evaluators graded computer simulated chest images using a visual grading analysis scoring (VGAS) scheme to quantify the benefit of using an anti-scatter grid were used for the clinical image quality measurement (number of simulated patientsâ€‰â€‰=â€‰â€‰80). The KSNR was used to calculate the improvement in physical image quality measured in a physical chest phantom. KSNR correlation with VGAS was assessed as a function of chest region (lung, spine and diaphragm/retrodiaphragm), and as a function of x-ray tube voltage in a given chest region. The correlation of the latter was determined by the Pearson correlation coefficient. VGAS and KSNR image quality metrics demonstrated no correlation in the lung region but did show correlation in the spine and diaphragm/retrodiaphragmatic regions. However, there was no correlation as a function of tube voltage in any region; a Pearson correlation coefficient (R) ofâ€‰â€‰â€‘0.93 (pâ€‰â€‰=â€‰â€‰0.015) was found for lung, a coefficient (R) ofâ€‰â€‰â€‘0.95 (pâ€‰â€‰=â€‰â€‰0.46) was found for spine, and a coefficient (R) ofâ€‰â€‰â€‘0.85 (pâ€‰â€‰=â€‰â€‰0.015) was found for diaphragm. All demonstrate strong negative correlations indicating conflicting results, i.e. KSNR increases with tube voltage but VGAS decreases. Medical physicists should use the KSNR metric with caution when assessing any potential improvement in clinical chest image quality when introducing an anti-scatter grid for CR imaging, especially in the lung region. This metric may also be a limited descriptor of clinical chest image quality as a function of tube voltage when a grid is used routinely.
Moore, C S; Wood, T J; Saunderson, J R; Beavis, A W
2015-12-01
This work assessed the appropriateness of the signal-to-noise ratio improvement factor (KSNR) as a metric for the optimisation of computed radiography (CR) of the chest. The results of a previous study in which four experienced image evaluators graded computer simulated chest images using a visual grading analysis scoring (VGAS) scheme to quantify the benefit of using an anti-scatter grid were used for the clinical image quality measurement (number of simulated patients??=??80). The KSNR was used to calculate the improvement in physical image quality measured in a physical chest phantom. KSNR correlation with VGAS was assessed as a function of chest region (lung, spine and diaphragm/retrodiaphragm), and as a function of x-ray tube voltage in a given chest region. The correlation of the latter was determined by the Pearson correlation coefficient. VGAS and KSNR image quality metrics demonstrated no correlation in the lung region but did show correlation in the spine and diaphragm/retrodiaphragmatic regions. However, there was no correlation as a function of tube voltage in any region; a Pearson correlation coefficient (R) of??-0.93 (p??=??0.015) was found for lung, a coefficient (R) of??-0.95 (p??=??0.46) was found for spine, and a coefficient (R) of??-0.85 (p??=??0.015) was found for diaphragm. All demonstrate strong negative correlations indicating conflicting results, i.e. KSNR increases with tube voltage but VGAS decreases. Medical physicists should use the KSNR metric with caution when assessing any potential improvement in clinical chest image quality when introducing an anti-scatter grid for CR imaging, especially in the lung region. This metric may also be a limited descriptor of clinical chest image quality as a function of tube voltage when a grid is used routinely. PMID:26540441
Diversity of the Vaginal Microbiome Correlates With Preterm Birth
Hyman, Richard W.; Fukushima, Marilyn; Jiang, Hui; Fung, Eula; Rand, Larry; Johnson, Brittni; Vo, Kim Chi; Caughey, Aaron B.; Hilton, Joan F.; Davis, Ronald W.
2014-01-01
Reproductive tract infection is a major initiator of preterm birth (PTB). The objective of this prospective cohort study of 88 participants was to determine whether PTB correlates with the vaginal microbiome during pregnancy. Total DNA was purified from posterior vaginal fornix swabs during gestation. The 16S ribosomal RNA gene was amplified using polymerase chain reaction primers, followed by chain-termination sequencing. Bacteria were identified by comparing contig consensus sequences with the Ribosomal Database Project. Dichotomous responses were summarized via proportions and continuous variables via means Â± standard deviation. Mean Shannon Diversity index differed by Welch t test (P = .00016) between caucasians with PTB and term gestation. Species diversity was greatest among African Americans (P = .0045). Change in microbiome/Lactobacillus content and presence of putative novel/noxious bacteria did not correlate with PTB. We conclude that uncultured vaginal bacteria play an important role in PTB and race/ethnicity and sampling location are important determinants of the vaginal microbiome. PMID:23715799
Rocket Auroral Correlator Experiment
NASA Technical Reports Server (NTRS)
LaBelle, James
2003-01-01
Dartmouth College provided a multi-channel high- and low- frequency wave receivers, including active sensors on deployable booms, to the Rocket Auroral Correlator Experiment launched from Poker Flat, Alaska, in January 2002. College also performed preliminary analysis of the data. Details are outlined in chronological order.
Sensory Correlations in Autism
ERIC Educational Resources Information Center
Kern, Janet K.; Trivedi, Madhukar H.; Grannemann, Bruce D.; Garver, Carolyn R.; Johnson, Danny G.; Andrews, Alonzo A.; Savla, Jayshree S.; Mehta, Jyutika A.; Schroeder, Jennifer L.
2007-01-01
This study examined the relationship between auditory, visual, touch, and oral sensory dysfunction in autism and their relationship to multisensory dysfunction and severity of autism. The Sensory Profile was completed on 104 persons with a diagnosis of autism, 3 to 56 years of age. Analysis showed a significant correlation between the different…
Neuroanatomical Correlates of Intelligence
ERIC Educational Resources Information Center
Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.
2009-01-01
With the advancement of image acquisition and analysis methods in recent decades, unique opportunities have emerged to study the neuroanatomical correlates of intelligence. Traditional approaches examining global measures have been complemented by insights from more regional analyses based on pre-defined areas. Newer state-of-the-art approaches…
Neuroanatomical Correlates of Intelligence
ERIC Educational Resources Information Center
Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.
2009-01-01
With the advancement of image acquisition and analysis methods in recent decades, unique opportunities have emerged to study the neuroanatomical correlates of intelligence. Traditional approaches examining global measures have been complemented by insights from more regional analyses based on pre-defined areas. Newer state-of-the-art approachesâ€¦
Hand skeletal maturity and its correlation with mandibular dental development
Pousti, Maryam; Adelianfar, Elahe
2014-01-01
Objectives: Assessment of pubertal status and pubertal growth spurt in orthodontic patients has a considerable impact on the diagnosis, treatment plan and the outcome of orthodontic treatments. Hand-wrist radiography is routinely used to evaluate skeletal development. Some studies have shown that there is an association between bone development and different stages of dental calcification; therefore, the stages of dental calcification can be used as the first tool for diagnosis, in case there is an association. This study was performed with the aim to evaluate the association between the phases of dental development and the stages of skeletal maturity. Study design: In this study, a total of 52 patients (26 males and 26 females), referring to Mashhad School of Dentistry for orthodontic treatment, were evaluated; the subjects were within the age range of 9-14 years. Hand-wrist radiographic evaluation of skeletal maturation was performed using Fishman method. Also, the Demirjian method was used to identify the stages of dental calcification by panoramic radiographs. Independent t-test and Spearman correlation coefficient were used for data analyses. Results: The mean age of males and females was 11.05 ± 1.05 and 10.62 ± 1.12 years, respectively (p=0.156). The Spearman correlation coefficients between skeletal maturity indicators (SMIs) and developmental stages of mandibular left and right canines and second molars were significant in males only (p<0.05). Also, correlation coefficients were significant between adductor sesamoid ossification and mandibular right and left canines developmental stages in males (p<0.05). Conclusions: Findings of this study showed that the correlation between dental developmental stages and skeletal maturity only were significant in males; thus, different skeletal maturity patterns in males and females might be perceptible. Key words:Skeletal maturation, hand-wrist radiography, panoramic radiography. PMID:25136430
Correlations and Ostwald ripening
NASA Technical Reports Server (NTRS)
Marder, M.
1987-01-01
A previously developed model (Weins and Cahn, 1973) describing the growth of spheres of a second phase in metal alloys (Ostwald coarsening) is slightly modified to make it possible to study the complete time evolution of the system rather than simply the late-stage scaling behavior. Closed equations are obtained which describe the time evolution of two-particle correlations in the system. The development of the correlations is analyzed, and simpler expressions are found and solved numerically. The results are compared with experimental data for different systems (e.g., Ni-Al, Ni-Cr-Al, Co-Ni-Cr-Ti, Cu-Co, and MgO-Fe), alternate methods, and existing theories.
Correlators in nontrivial backgrounds
Mello Koch, Robert de; Ives, Norman; Stephanou, Michael
2009-01-15
Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.
Digital demodulator-correlator
NASA Technical Reports Server (NTRS)
Layland, J. W.; Martin, W. L.; Zygielbaum, A. I.; Goldstein, R. M.; Hubbard, W. P. (inventors)
1978-01-01
An apparatus for demodulation and correlation of a code modulated 10 MHz signal is presented. The apparatus is comprised of a sample and hold analog-to-digital converter synchronized by a frequency coherent 40 MHz pulse to obtain four evenly spaced samples of each of the signal. Each sample is added or subtracted to or from one of four accumulators to or from the separate sums. The correlation functions are then computed. As a further feature of the invention, multipliers are each multiplied by a squarewave chopper signal having a period that is long relative to the period of the received signal to foreclose contamination of the received signal by leakage from either of the other two terms of the multipliers.
Quantitative correlation of breast tissue parameters using magnetic resonance and X-ray mammography.
Graham, S. J.; Bronskill, M. J.; Byng, J. W.; Yaffe, M. J.; Boyd, N. F.
1996-01-01
Previous investigators have shown that there is a strong association between the fraction of fibroglandular tissue within the breast as determined by X-ray mammography (per cent density) and breast cancer risk. In this study, the quantitative correlation between per cent density and two objective magnetic resonance (MR) parameters of breast tissue, relative water content and mean T2 relaxation time, as investigated for 42 asymptomatic subjects. Using newly developed, rapid techniques MR measurements were performed on a volume-of-interest incorporating equal, representative portions of both breasts. X-ray mammograms of each subject were digitised and analysed semiautomatically to determine per cent density. Relative water content showed a strong positive correlation with per cent density (Pearson correlation coefficient rp = 0.79, P < 0.0001) and mean T2 value showed a strong negative correlation with per cent density (rp = -0.61, P < 0.0001). The MR and X-ray parameters were also associated with sociodemographic and anthropometric risk factors for breast cancer (P < 0.05). The potential use of MR parameters to assess risk of breast cancer and to provide a frequent, non-hazardous monitor of breast parenchyma is discussed. Images Figure 2 PMID:8546901
Yan, Qinling; Tang, Sanyi; Gabriele, Sandra; Wu, Jianhong
2016-02-01
News reporting has the potential to modify a community×łs knowledge of emerging infectious diseases and affect peoples' attitudes and behavior. Here we developed a quantitative approach to evaluate the effects of media on such behavior. Statistically significant correlations between the number of new hospital notifications, during the 2009 A/H1N1 influenza epidemic in the Shaanxi province of China, and the number of daily news items added to eight major websites were found from Pearson correlation and cross-correlation analyses. We also proposed a novel model to examine the implication for transmission dynamics of these correlations. The model incorporated the media impact function into the intensity of infection, and enhanced the traditional epidemic SEIR model with the addition of media dynamics. We used a nonlinear least squares estimation to identify the best-fit parameter values in the model from the observed data. We also carried out the uncertainty and sensitivity analyses to determine key parameters during early phase of the disease outbreak for the final outcome of the outbreak with media impact. The findings confirm the importance of responses by individuals to the media reports, with behavior changes having important consequence for the emerging infectious disease control. Therefore, for mitigating emerging infectious diseases, media reports should be focused on how to guide people×łs behavioral changes, which are critical for limiting the spread of disease. PMID:26582723
Stature and gender determination and their correlation using odontometry and skull anthropometry
Gupta, Amit; Kumar, Kiran; Shetty, Devi Charan; Wadhwan, Vijay; Jain, Anshi; Khanna, Kaveri Surya
2014-01-01
Background: When the body has been mutilated, it is common to have the extremities or head amputated from the trunk. In concern with forensic odontology, an estimate must have been made based on the correlation of osteometry along with odontometry in determining sex, race and stature. Objective: The objective of this study is to investigate and correlate height and gender from odontometry and anthropometric data of the skull. Materials and Methods: The study was conducted in the Department of Oral and Maxillofacial Pathology and Microbiology, I.T.S Center for Dental studies and Research, Muradnagar, Ghaziabad (UP) with the representative study subjects of 60 patients as 30 males and 30 females in the age group of 15-25 years. The selected parameters were measured and then correlated to investigate stature and gender from odontometry and anthropometric data of the skull. Results: On linear regression analysis, the selected parameters were found to be statistically significant predictor of height. It was also established by Karl Pearson's coefficient correlation that the left mandibular canine index for female was statistically significant to show sexual dimorphism. Conclusion: In the emerging field of forensic odontology, skull anthropometry, odontometry exhibits stature determination and strong sexual dimorphism. PMID:25125917
Genetics Home Reference: Pearson marrow-pancreas syndrome
... within cells that use oxygen to convert the energy from food into a form cells can use. This process is called oxidative phosphorylation. Although most DNA is packaged in chromosomes within the nucleus (nuclear DNA), mitochondria also have a small amount of ...
Standardized Pearson type 3 density function area tables
NASA Technical Reports Server (NTRS)
Cohen, A. C.; Helm, F. R.; Sugg, M.
1971-01-01
Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods.
Selective correlations; not voodoo.
Rosenblatt, J D; Benjamini, Y
2014-12-01
The problem of "voodoo" correlations-exceptionally high observed correlations in selected regions of the brain-is well recognized in neuroimaging. It arises when quantities of interest are estimated from the same data that was used to select them as interesting. In statistical terminology, the problem of inference following selection from the same data is that of selective inference. Motivated by the unwelcome side-effects of splitting the data- the recommended remedy-we adapt the recent developments in selective inference in order to construct confidence intervals (CIs) with good reproducibility prospects, even if selection and estimation are done with the same data. These intervals control the expected proportion of non-covered correlations in the selected voxels-the False Coverage Rate (FCR). They extend further toward zero than standard intervals, thus attenuating the impression made by highly biased observed correlations. They do so adaptively, in that they coincide with the standard CIs when far away from the selection point. We complement existing analytic proofs with a simulation, showing that the proposed intervals control the FCR in realistic social neuroscience problems. We also suggest a "confidence calibration plot", to allow the intervals to be reported in a clear and interpretable way. Applying the proposed methodology on a loss-aversion study, we demonstrate that with the sample size and selection type employed, selection bias is considerable. Finally, selective intervals are compared to the currently recommended data-splitting approach. We discover that our approach has more power and typically more informative, as no data is discarded. Computation of the intervals is implemented in an accompanying software package. PMID:25153699
NASA Astrophysics Data System (ADS)
Li, Ming-Chiang
2009-05-01
Interferoceiver is a true correlation receiver and capable of overcoming severe problems caused by conventional super heterodyne receivers, such as range inaccuracy, Doppler range ambiguity, fratricides, excessive clutter contamination, undue inter system interference, etc. We had discussed the above capabilities in our early publications. In this paper, we will present the experimental progresses on interferoceiver as well as encountered obstacles. The technological revolution in radar and electronic warfare is within sight.
Propensities, correlations, and metaphysics
NASA Astrophysics Data System (ADS)
Redhead, Michael
1992-03-01
An attempt is made to defend realism and the absence of space-like causation in quantum mechanics, by invoking indeterminism and a new necessary condition for stochastic causality, we term robustness. This condition is defended against recent critical attacks by Cartwright and Jones, and by Healey, and the violation of the robustness condition in Bell-type correlation experiments is shown to follow if an appropriate interpretation of the state vector is employed.
Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde
2012-01-01
Purpose: From independently conducted free-response receiver operating characteristic (FROC) and receiver operating characteristic (ROC) experiments, to study fixed-reader associations between three estimators: the area under the alternative FROC (AFROC) curve computed from FROC data, the area under the ROC curve computed from FROC highest rating data, and the area under the ROC curve computed from confidence-of-disease ratings. Methods: Two hundred mammograms, 100 of which were abnormal, were processed by two image-processing algorithms and interpreted by four radiologists under the FROC paradigm. From the FROC data, inferred-ROC data were derived, using the highest rating assumption. Eighteen months afterwards, the images were interpreted by the same radiologists under the conventional ROC paradigm; conventional-ROC data (in contrast to inferred-ROC data) were obtained. FROC and ROC (inferred, conventional) data were analyzed using the nonparametric area-under-the-curve (AUC), (AFROC and ROC curve, respectively). Pearson correlation was used to quantify the degree of association between the modality-specific AUC indices and standard errors were computed using the bootstrap-after-bootstrap method. The magnitude of the correlations was assessed by comparison with computed Obuchowski-Rockette fixed reader correlations. Results: Average Pearson correlations (with 95% confidence intervals in square brackets) were: Corr(FROC, inferred ROC) = 0.76[0.64, 0.84] > Corr(inferred ROC, conventional ROC) = 0.40[0.18, 0.58] > Corr (FROC, conventional ROC) = 0.32[0.16, 0.46]. Conclusions: Correlation between FROC and inferred-ROC data AUC estimates was high. Correlation between inferred- and conventional-ROC AUC was similar to the correlation between two modalities for a single reader using one estimation method, suggesting that the highest rating assumption might be questionable. PMID:23039631
Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde
2012-10-15
Purpose: From independently conducted free-response receiver operating characteristic (FROC) and receiver operating characteristic (ROC) experiments, to study fixed-reader associations between three estimators: the area under the alternative FROC (AFROC) curve computed from FROC data, the area under the ROC curve computed from FROC highest rating data, and the area under the ROC curve computed from confidence-of-disease ratings. Methods: Two hundred mammograms, 100 of which were abnormal, were processed by two image-processing algorithms and interpreted by four radiologists under the FROC paradigm. From the FROC data, inferred-ROC data were derived, using the highest rating assumption. Eighteen months afterwards, the images were interpreted by the same radiologists under the conventional ROC paradigm; conventional-ROC data (in contrast to inferred-ROC data) were obtained. FROC and ROC (inferred, conventional) data were analyzed using the nonparametric area-under-the-curve (AUC), (AFROC and ROC curve, respectively). Pearson correlation was used to quantify the degree of association between the modality-specific AUC indices and standard errors were computed using the bootstrap-after-bootstrap method. The magnitude of the correlations was assessed by comparison with computed Obuchowski-Rockette fixed reader correlations. Results: Average Pearson correlations (with 95% confidence intervals in square brackets) were: Corr(FROC, inferred ROC) = 0.76[0.64, 0.84] > Corr(inferred ROC, conventional ROC) = 0.40[0.18, 0.58] > Corr (FROC, conventional ROC) = 0.32[0.16, 0.46]. Conclusions: Correlation between FROC and inferred-ROC data AUC estimates was high. Correlation between inferred- and conventional-ROC AUC was similar to the correlation between two modalities for a single reader using one estimation method, suggesting that the highest rating assumption might be questionable.
Energy calibration via correlation
NASA Astrophysics Data System (ADS)
Maier, Daniel; Limousin, Olivier
2016-03-01
The main task of an energy calibration is to find a relation between pulse-height values and the corresponding energies. Doing this for each pulse-height channel individually requires an elaborated input spectrum with an excellent counting statistics and a sophisticated data analysis. This work presents an easy to handle energy calibration process which can operate reliably on calibration measurements with low counting statistics. The method uses a parameter based model for the energy calibration and concludes on the optimal parameters of the model by finding the best correlation between the measured pulse-height spectrum and multiple synthetic pulse-height spectra which are constructed with different sets of calibration parameters. A CdTe-based semiconductor detector and the line emissions of an 241Am source were used to test the performance of the correlation method in terms of systematic calibration errors for different counting statistics. Up to energies of 60 keV systematic errors were measured to be less than ~ 0.1 keV. Energy calibration via correlation can be applied to any kind of calibration spectra and shows a robust behavior at low counting statistics. It enables a fast and accurate calibration that can be used to monitor the spectroscopic properties of a detector system in near realtime.
Neural correlates of gratitude
Fox, Glenn R.; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others. PMID:26483740
Variable angle correlation spectroscopy
Lee, Y K
1994-05-01
In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with {sup 13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.
Percolation in correlated systems
NASA Astrophysics Data System (ADS)
Marinov, Vesselin
In this thesis we study various problems in dependent percolation theory. In the first part of this thesis we study disordered q-state Potts models as examples of systems in which there is percolation for an arbitrary low density and no percolation for arbitrary high density of occupied sites. In the second part of the thesis we study dependent percolation models in which the correlations between the site occupation variables are long range, i.e. decaying as r-a for a < d, where r is the separation between any two sites and d is the dimension of the model. Scaling analysis suggests [1] that such long range correlated percolation models define a new percolation universality classes with critical exponents depending on a. We develop a field theoretic description of these models in an attempt to calculate the critical exponents of the transition in an double expansion in terms of epsilon = 6-d and infinity = 4- a. In the third part we study the percolation transition for two specific long range correlated percolation models on the 3 dimensional integer square lattice. These two percolation models are derived from the Voter model and the Harmonic crystal respectively. Our simulation results confirm the basic scaling arguments and the field theoretic results.
Neural correlates of gratitude.
Fox, Glenn R; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others. PMID:26483740
Temperament correlates with training success in adult rhesus macaques.
Coleman, Kristine; Tully, Leigh Ann; McMillan, Jennifer L
2005-01-01
In recent years there has been a marked increase in awareness of issues involving the psychological well-being of nonhuman primates (NHPs) used in biomedical research. As a result, many facilities are starting to train primates to voluntarily cooperate with veterinary, husbandry, and research procedures, such as remaining still for blood draws or injections. Such training generally reduces the stress associated with these procedures, resulting in calmer animals and, ultimately, better research models. However, such training requires great investments in time, and there can be vast individual differences in training success. Some animals learn tasks quickly, while others make slower progress in training. In this study, we examined whether temperament, as measured by response to a novel food object, correlated with the amount of time it took to train 20 adult female rhesus macaques to perform a simple task. The monkeys were categorized as "exploratory" (i.e., inspected a novel object placed in the home cage within 10 sec), "moderate" (i.e., inspected the object within 10-180 sec), or "inhibited" (i.e., did not inspect the object within 3 min). We utilized positive reinforcement techniques to train the monkeys to touch a target (PVC pipe shaped like an elbow) hung on their cage. Temperament correlated with training success in this study (Pearson chi2=7.22, df=2, P=0.03). We easily trained over 75% of the animals that inspected the novel food (i.e., exploratory or moderate individuals) to touch the target. However, only 22% of the inhibited monkeys performed the task. By knowing which animals may not respond to conventional training methods, we may be able to develop alternate training techniques to address their specific needs. In addition, these results will allow us to screen monkeys to be assigned to research projects in which they will be trained, with the goal of obtaining the best candidates for those studies. PMID:15645460
Gupta, Mohit; Divyashree, R; Abhilash, PR; A Bijle, Mohammed Nadeem; Murali, KV
2013-01-01
Introduction: Chronological age, dental development, height and weight measurements, sexual maturation characteristics and skeletal age are some biological indicators that have been used to identify time of growth. Many researchers have agreed that skeletal maturity is closely related to the craniofacial growth, and bones of hand and wrist are reliable parameters in assessing it. The complete hand and wrist radiograph involves 30 bones and assessment of these bones is one elaborate task. The present study is therefore, undertaken to assess the correlation between the chronological age, dental age and skeletal ages among different types of twins. Materials and Methods: The study consisted of 60 subjects (30 twins) aged 8 to 16 years, divided into group of 10 monozygotic, 10 dizygotic and 10 mixed sex twins. The sample was selected from Twin Survey- 2008 conducted by Department of Orthodontics and Dentofacial Orthopaedics, Sree Balaji Dental College and Hospital, Chennai. Their zygosity was determined by sex, blood groups and by the parent. The chronological age was measured by the date of birth given by the parents. Panoramic and hand wrist x-rays were taken. Dental age was assessed by Demerjian et al method and skeletal age by Greulich and Pyle method. The correlation among twins in dental and skeletal ages with the chronological age was assessed using Correlation Coefficient and Student's't' Test. Results: The obtained data was fed into the computer and statistical analysis was done for the same using the SPSS version 10.0. Statistical significance was tested at P<0.05 level. Mean and Standard Deviation, Correlation Coefficient, Student's't' Test statistical methods were employed. The result showed highly significant 'p' value as <0.001 in all the correlations except for mixed pairs. Descriptive statistics in most of the areas demonstrated a non-significant result between zygosity groups. Conclusion: There is a correlation existing between the individualâ€™s chronological age, dental age and skeletal age and correlation also exists in the twin pairs of the same zygosity and among each pair but no correlation exists between different zygotic twins. How to cite this article: Gupta M, Divyashree R, Abhilash P R, Bijle M N A, Murali K V. Correlation between Chronological Age, Dental Age and Skeletal Age among Monozygoyic and Dizygotic Twins. J Int Oral Health 2013; 3(1):16-22. PMID:24155573
Bootstrapped Deattenuated Correlation: Nonnormal Distributions
ERIC Educational Resources Information Center
Padilla, Miguel A.; Veprinsky, Anna
2014-01-01
Correlation attenuation due to measurement error and a corresponding correction, the deattenuated correlation, have been known for over a century. Nevertheless, the deattenuated correlation remains underutilized. A few studies in recent years have investigated factors affecting the deattenuated correlation, and a couple of them provide alternative…
Holden, Kisha B.; Bradford, L. Dianne; Hall, Stephanie P.; Belton, Allyson S.
2014-01-01
The purpose of this cross-sectional pilot study was to determine the prevalence and correlates of depressive symptoms and resiliency among 290 African American women (AAW) in a community-based primary health care center. Descriptive statistics, Pearson product-moment correlation, and logistic regression analyses were conducted. Findings indicate that depressive symptoms are experienced by 49% of the participants, while 10% indicated a history of suicidal ideation. Participants had moderately high resiliency scores that had a statistically significant inverse relationship with depressive symptoms. This suggests that resiliency is potentially a protective factor for depressive symptoms. Depressive symptoms were positively correlated with participantsâ€™ diagnosis of at least one chronic disease. The strongest predictors of depressive symptoms were previous diagnoses of a mental health condition and unemployment. This study identifies risk and potential protective factors for depression among a clinic sample of AAW. PMID:24241263
Kim, Myoung-Kwon; Kim, Tae Hoon; Kim, Seong-Gil
2015-01-01
[Purpose] This study aimed to investigate the correlation between the cognitive level of the elderly and their attitude towards the living environment. [Subjects and Methods] A total of 80 elderly people hospitalized in a nursing home in K city, South Korea, participated in this study. Pearson correlation analysis was used to test the relationships between scores on the Mini Mental State Examination-Korean Version and Measurement of Quality of the Environment (facilitators and obstacles). [Results] A positive and moderately strong correlation (r = 0.462) was found between scores on the Mini Mental State Examination and the Measurement of Quality of the Environment (obstacle). [Conclusion] In a nursing home, patients with relatively higher cognitive levels can perceive more obstacles in the surrounding environment. PMID:26696742
Flatbands under Correlated Perturbations
NASA Astrophysics Data System (ADS)
Bodyfelt, Joshua D.; Leykam, Daniel; Danieli, Carlo; Yu, Xiaoquan; Flach, Sergej
2014-12-01
Flatband networks are characterized by the coexistence of dispersive and flatbands. Flatbands (FBs) are generated by compact localized eigenstates (CLSs) with local network symmetries, based on destructive interference. Correlated disorder and quasiperiodic potentials hybridize CLSs without additional renormalization, yet with surprising consequences: (i) states are expelled from the FB energy EFB, (ii) the localization length of eigenstates vanishes as ? 1 /ln (E -EFB) , (iii) the density of states diverges logarithmically (particle-hole symmetry) and algebraically (no particle-hole symmetry), and (iv) mobility edge curves show algebraic singularities at EFB . Our analytical results are based on perturbative expansions of the CLSs and supported by numerical data in one and two lattice dimensions.
Loturco, I; Barbosa, A C; Nocentini, R K; Pereira, L A; Kobal, R; Kitamura, K; Abad, C C C; Figueiredo, P; Nakamura, F Y
2016-03-01
Swimmers are often tested on both dry-land and in swimming exercises. The aim of this study was to test the relationships between dry-land, tethered force-time curve parameters and swimming performances in distances up to 200â€‰m. 10 young male high-level swimmers were assessed using the maximal isometric bench-press and quarter-squat, mean propulsive power in jump-squat, squat and countermovement jumps (dry-land assessments), peak force, average force, rate of force development (RFD) and impulse (tethered swimming) and swimming times. Pearson product-moment correlations were calculated among the variables. Peak force and average force were very largely correlated with the 50- and 100-m swimming performances (r=-â€‰0.82 and -0.74, respectively). Average force was very-largely/largely correlated with the 50- and 100-m performances (r=-â€‰0.85 and -0.67, respectively). RFD and impulse were very-largely correlated with the 50-m time (r=-â€‰0.72 and -0.76, respectively). Tethered swimming parameters were largely correlated (r=0.65 to 0.72) with mean propulsive power in jump-squat, squat-jump and countermovement jumps. Finally, mean propulsive power in jump-squat was largely correlated (r=-â€‰0.70) with 50-m performance. Due to the significant correlations between dry-land assessments and tethered/actual swimming, coaches are encouraged to implement strategies able to increase leg power in sprint swimmers. PMID:26669251
Cluster-cluster correlations and constraints on the correlation hierarchy
NASA Technical Reports Server (NTRS)
Hamilton, A. J. S.; Gott, J. R., III
1988-01-01
The hypothesis that galaxies cluster around clusters at least as strongly as they cluster around galaxies imposes constraints on the hierarchy of correlation amplitudes in hierachical clustering models. The distributions which saturate these constraints are the Rayleigh-Levy random walk fractals proposed by Mandelbrot; for these fractal distributions cluster-cluster correlations are all identically equal to galaxy-galaxy correlations. If correlation amplitudes exceed the constraints, as is observed, then cluster-cluster correlations must exceed galaxy-galaxy correlations, as is observed.
Partner's influences and other correlates of prenatal alcohol use.
van der Wulp, Nickie Y; Hoving, Ciska; de Vries, Hein
2015-04-01
To investigate the influence of partners on alcohol consumption in pregnant women within the context of other factors. A Dutch nationwide online cross-sectional study among 158 pregnant women and their partners was conducted. To identify correlates of prenatal alcohol use, including perceived and reported partner norm (i.e. partner's belief regarding acceptability of prenatal alcohol use), partner modeling (i.e. partner's alcohol use during the woman's pregnancy) and partner support (i.e. partner's help in abstaining from alcohol during pregnancy), independent sample T-tests and Chi square tests were conducted. Correlation analyses tested the relationship between perceived and reported partner influence. Multivariate logistic hierarchical regression analyses tested the independent impact of partner's perceived and reported influence next to other correlates from the I-Change Model. Pregnant women who consumed alcohol perceived a weaker partner norm (p < 0.001) and less partner modeling (p < 0.05), with the partner reporting a weaker norm (p < 0.001), more drinking days per week (p < 0.05) and weaker support (p < 0.05). Perceived and reported partner norm, modeling and support were positively related (respectively p < 0.01, p < 0.01 and p < 0.05). The multivariate analyses demonstrated that pregnant women with a higher education who perceived lower severity of harm due to prenatal alcohol use and a weaker partner norm were more likely to use alcohol (R(2) = 0.42). This study demonstrated that perceived partner norm was the most critical of the constructs of perceived and reported partner influences in explaining prenatal alcohol use. PMID:25087003
Grayscale Optical Correlator Workbench
NASA Technical Reports Server (NTRS)
Hanan, Jay; Zhou, Hanying; Chao, Tien-Hsin
2006-01-01
Grayscale Optical Correlator Workbench (GOCWB) is a computer program for use in automatic target recognition (ATR). GOCWB performs ATR with an accurate simulation of a hardware grayscale optical correlator (GOC). This simulation is performed to test filters that are created in GOCWB. Thus, GOCWB can be used as a stand-alone ATR software tool or in combination with GOC hardware for building (target training), testing, and optimization of filters. The software is divided into three main parts, denoted filter, testing, and training. The training part is used for assembling training images as input to a filter. The filter part is used for combining training images into a filter and optimizing that filter. The testing part is used for testing new filters and for general simulation of GOC output. The current version of GOCWB relies on the mathematical software tools from MATLAB binaries for performing matrix operations and fast Fourier transforms. Optimization of filters is based on an algorithm, known as OT-MACH, in which variables specified by the user are parameterized and the best filter is selected on the basis of an average result for correct identification of targets in multiple test images.
CONDITIONAL DISTANCE CORRELATION
Wang, Xueqin; Pan, Wenliang; Hu, Wenhao; Tian, Yuan; Zhang, Heping
2015-01-01
Statistical inference on conditional dependence is essential in many fields including genetic association studies and graphical models. The classic measures focus on linear conditional correlations, and are incapable of characterizing non-linear conditional relationship including non-monotonic relationship. To overcome this limitation, we introduces a nonparametric measure of conditional dependence for multivariate random variables with arbitrary dimensions. Our measure possesses the necessary and intuitive properties as a correlation index. Briefly, it is zero almost surely if and only if two multivariate random variables are conditionally independent given a third random variable. More importantly, the sample version of this measure can be expressed elegantly as the root of a V or U-process with random kernels and has desirable theoretical properties. Based on the sample version, we propose a test for conditional independence, which is proven to be more powerful than some recently developed tests through our numerical simulations. The advantage of our test is even greater when the relationship between the multivariate random variables given the third random variable cannot be expressed in a linear or monotonic function of one random variable versus the other. We also show that the sample measure is consistent and weakly convergent, and the test statistic is asymptotically normal. By applying our test in a real data analysis, we are able to identify two conditionally associated gene expressions, which otherwise cannot be revealed. Thus, our measure of conditional dependence is not only an ideal concept, but also has important practical utility. PMID:26877569
Correlative Measurements Program
NASA Technical Reports Server (NTRS)
Parsons, C. L.
1988-01-01
The GSFC Correlative Measurements Program at the Wallops Flight Facility was represented on the Satellite/Satellite Intercomparisons Working Group. The Correlative Measurements Program uses the Rocket Ozonesonde (ROCOZ-A) and the Electrochemical Concentration Cell (ECC) balloon borne ozonesonde to measure the vertical profile of ozone amount in the atmosphere. The balloon work is described in a separate report. The ROCOZ-A instrument was used for many years to provide in situ truth data for various satellite ozone measuring systems, such as SBUV on Nimbus-7, SAGE-II, SBUV-II on the NOAA series of polar orbiting satellites, SME, LIMS, etc. The particular data sets of interest to the Ozone Trends Panel Working Group were collected at Natal, Brazil. The major results produced for and used by the Ozone Trends Panel are shown. The ROCOZ-A average ozone density profile is plotted versus altitude on the left. ECC ozonesondes were used for the portion of the profile below 20 km, the lower limit for ROCOZ-A. The difference between SAGE-II and ROCOZ-A average density profiles is shown.
Piao, Lin; Fu, Zuntao; Yuan, Naiming
2016-01-01
In this study, relations between winter-time Pacific-Northern America pattern (PNA)/East Pacific wave-train (EPW) and winter-time drought in the west United States over the period of 1951-2010 are analyzed. Considering traditional Pearson's Correlation Coefficient can be influenced by non-stationarity and nonlinearity, a recently proposed method, Detrended Partial-Cross-Correlation Analysis (DPCCA) is applied. With DPCCA, we analyzed the "intrinsic" correlations between PNA/EPW and the winter drought with possible effects of ENSO and PDO removed. We found, i) significant negative correlations between PNA/EPW and drought on time scales of 5-6 years after removing the effects of ENSO, ii) and significant negative correlations between PNA/EPW and drought on time scales of 15-25 years after removing the effects of PDO. By further studying the temporal evolutions of the "intrinsic" correlations, we found on time scales of 5-6 years, the "intrinsic" correlations between PNA/EPW and drought can vary severely with time, but for most time, the correlations are negative. While on interdecadal (15-25 years) time scales, after the effects of PDO removed, unlike the relations between PNA and drought, the "intrinsic" correlations between EPW and drought takes nearly homogeneous-sign over the whole period, indicating a better model can be designed by using EPW. PMID:26813741
PREFACE: Correlated Electrons (Japan)
NASA Astrophysics Data System (ADS)
Miyake, Kazumasa
2007-03-01
This issue of Journal of Physics: Condensed Matter is dedicated to results in the field of strongly correlated electron systems under multiple-environment. The physics of strongly correlated electron systems (SCES) has attracted much attention since the discovery of superconductivity in CeCu_2 Si_2 by Steglich and his co-workers a quater-century ago. Its interest has been intensified by the discovery of high-Tc superconductivity in a series of cuprates with layered perovskite structure which are still under active debate. The present issue of Journal of Physics: Condensed Matter present some aspects of SCES physics on the basis of activities of a late project "Centre-Of-Excellence" supported by MEXT (Ministry of Education, Sports, Science, Culture and Technology of the Japanese Government). This project has been performed by a condensed matter physics group in the faculties of science and engineering science of Osaka University. Although this project also covers correlated phenomena in optics and nano-scale systems, we focus here on the issues of SCES related to superconductivity, mainly unconventional. The present issue covers the discussions on a new mechanism of superconductivity with electronic origin (critical valence fluctuation mechanism), interplay and unification of magnetism and superconductivity in SCES based on a systematic study of NQR under pressure, varieties of Fermi surface of Ce- and U-based SCES probed by the de Haas-van Alphen effect, electronic states probed by a bulk sensitive photoemission spectroscopy with soft X-ray, pressure induced superconductivity of heavy electron materials, pressure dependence of superconducting transition temperature based on a first-principle calculation, and new superconductors under very high-pressure. Some papers offer readers' reviews of the relevant fields and/or include new developments of this intriguing research field of SCES. Altogether, the papers within this issue outline some aspects of electronic states and superconductivity of SCES and related research fields, and the prospects of SCES physics. I hope that it will give an insight into the fascination of SCES research and a feeling for the advances made in the past years.
Wang, Shu-Hong; Sun, Yun-Feng; Liu, Yang; Zhou, Yang; Liu, Ying
2015-01-01
Pancreatic cancer typically carries a poor prognosis, and new methods of diagnosis and treatment are needed to improve outcomes for the disease. Non-invasive imaging techniques that accurately predict disease severity may aid in the treatment of pancreatic cancer patients. This study sought to investigate the correlation between computed tomography (CT) contrast enhancement and the histopathological grades and intratumoral angiogenesis in pancreatic carcinoma. The study included 54 patients with pancreatic carcinoma who underwent surgical resection in our hospital. All participants received a CT scan with contrast enhancement before surgery. Pathological specimens obtained during surgery were paraffin embedded for immunohistochemistry to assess microvessel density (MVD; CD31 staining) and angiogenesis activity [vascular endothelial growth factor (VEGF) staining]. Results were analyzed using t tests and Spearman correlation. CT enhancement of pancreatic tumors was negatively correlated with the pathological grade (rs=-0.784, P<0.05) and the MVD count in tumor hot spots (rs=-0.790, P<0.05). Additionally, the pathological grade positively correlated with MVD count (rs=0.516, P<0.05). However, there was no correlation between pathological grade and VEGF expression (rs=-0.195, P>0.05). Finally, MVD was higher in individuals positive for VEGF expression than in those negative for VEGF expression (P<0.05). Thus, the extent of CT enhancement is related to the MVD in tumor hot spots and the malignant degree of pancreatic carcinoma. This suggests CT can be used to reflect the disease severity and extent. PMID:26191248
Flatbands under correlated perturbations.
Bodyfelt, Joshua D; Leykam, Daniel; Danieli, Carlo; Yu, Xiaoquan; Flach, Sergej
2014-12-01
Flatband networks are characterized by the coexistence of dispersive and flatbands. Flatbands (FBs) are generated by compact localized eigenstates (CLSs) with local network symmetries, based on destructive interference. Correlated disorder and quasiperiodic potentials hybridize CLSs without additional renormalization, yet with surprising consequences: (i) states are expelled from the FB energy E_{FB}, (ii) the localization length of eigenstates vanishes as ??1/ln(E-E_{FB}), (iii) the density of states diverges logarithmically (particle-hole symmetry) and algebraically (no particle-hole symmetry), and (iv) mobility edge curves show algebraic singularities at E_{FB}. Our analytical results are based on perturbative expansions of the CLSs and supported by numerical data in one and two lattice dimensions. PMID:25526142
Neural correlates of frustration.
Abler, Birgit; Walter, Henrik; Erk, Susanne
2005-05-12
Psychological considerations suggest that the omission of rewards in humans comprises two effects: first, an allocentric effect triggering learning and behavioural changes potentially processed by dopaminergic neurons according to the prediction error theory; second, an egocentric effect representing the individual's emotional reaction, commonly called frustration. We investigated this second effect in the context of omission of monetary reward with functional magnetic resonance imaging. As expected, the contrast omission relative to receipt of reward led to a decrease in ventral striatal activation consistent with prediction error theory. Increased activation for this contrast was found in areas previously related to emotional pain: the right anterior insula and the right ventral prefrontal cortex. We interpreted this as a neural correlate of the egocentric effect. PMID:15858403
Onychotillomania: clinicopathologic correlations.
Reese, Jennifer M; Hudacek, Kristin D; Rubin, Adam I
2013-04-01
Onychotillomania represents an unusual dermatosis affecting the nail unit. The term refers to 'neurotic picking at a nail until it is permanently altered'. It can be difficult for dermatologists to diagnose, as typically patients will deny the self-destructive behavior and the clinical features may mimic other inflammatory conditions affecting the nail unit. Aside from the difficulty in establishing the diagnosis clinically, the histopathologic features of onychotillomania are nonspecific. With this limited knowledge, dermatopathologists could have difficulty in correlating the clinical and histopathologic features and determining the correct diagnosis. Establishing the diagnosis is critical, as onychotillomania is sometimes associated with major depression and obsessive-compulsive disorder, and can be a clue to uncovering these debilitating psychiatric disorders. Here we present two cases of onychotillomania and emphasize the clinical-pathological confrontation necessary to secure the diagnosis. PMID:23398617
NASA Astrophysics Data System (ADS)
Maguire, Charles F.
2013-08-01
The measurements of the anisotropic flow of single particles and particle pairs have provided some of the most compelling evidence for the creation of a strongly interacting quark-gluon plasma (sQGP) in relativistic heavy ion collisions, first at RHIC, and more recently at the LHC. Using PbPb collision data taken in the 2010 and 2011 heavy ion runs at the LHC, the CMS experiment has investigated a broad scope of these flow phenomena. The v2 elliptic flow coefficient has been extracted with four different methods to cross-check contributions from initial state fluctuations and non-flow correlations. The measurements of the v2 elliptic anisotropy have been extended to a transverse momentum of 60 GeV/c, which will enable the placement of new quantitative constraints on parton energy loss models as a function of path length in the sQGP medium. Additionally, for the first time at the LHC, the CMS experiment has extracted precise elliptic anisotropy coefficients for the ?0 meson in the centrality range 20-80% and over a transverse momentum range 1.6 to 8 GeV/c. These results are compared with both the ?0 results reported by the PHENIX detector at RHIC, and with the inclusive charged particle anisotropy results reported from the LHC. Finally, the CMS experiment has mounted an extensive study of charged hadron pair azimuthal correlations using a Fourier harmonic decomposition to fit the data. The relationship between these pair coefficients and the single particle harmonic flow coefficients can be explored for its insight into the early dynamics of this viscous medium.
Clinicopathological correlates of hyperparathyroidism.
Duan, Kai; Gomez Hernandez, Karen; Mete, Ozgur
2015-10-01
Hyperparathyroidism is a common endocrine disorder with potential complications on the skeletal, renal, neurocognitive and cardiovascular systems. While most cases (95%) occur sporadically, about 5% are associated with a hereditary syndrome: multiple endocrine neoplasia syndromes (MEN-1, MEN-2A, MEN-4), hyperparathyroidism-jaw tumour syndrome (HPT-JT), familial hypocalciuric hypercalcaemia (FHH-1, FHH-2, FHH-3), familial hypercalciuric hypercalcaemia, neonatal severe hyperparathyroidism and isolated familial hyperparathyroidism. Recently, molecular mechanisms underlying possible tumour suppressor genes (MEN1, CDC73/HRPT2, CDKIs, APC, SFRPs, GSK3?, RASSF1A, HIC1, RIZ1, WT1, CaSR, GNA11, AP2S1) and proto-oncogenes (CCND1/PRAD1, RET, ZFX, CTNNB1, EZH2) have been uncovered in the pathogenesis of hyperparathyroidism. While bi-allelic inactivation of CDC73/HRPT2 seems unique to parathyroid malignancy, aberrant activation of cyclin D1 and Wnt/?-catenin signalling has been reported in benign and malignant parathyroid tumours. Clinicopathological correlates of primary hyperparathyroidism include parathyroid adenoma (80-85%), hyperplasia (10-15%) and carcinoma (<1-5%). Secondary hyperparathyroidism generally presents with diffuse parathyroid hyperplasia, whereas tertiary hyperparathyroidism reflects the emergence of autonomous parathyroid hormone (PTH)-producing neoplasm(s) from secondary parathyroid hyperplasia. Surgical resection of abnormal parathyroid tissue remains the only curative treatment in primary hyperparathyroidism, and parathyroidectomy specimens are frequently encountered in this setting. Clinical and biochemical features, including intraoperative PTH levels, number, weight and size of the affected parathyroid gland(s), are crucial parameters to consider when rendering an accurate diagnosis of parathyroid proliferations. This review provides an update on the expanding knowledge of hyperparathyroidism and highlights the clinicopathological correlations of this prevalent disease. PMID:26163537
``A Desideratum in Spectrology'': an Editor's Lament in the Great Correlation Era
NASA Astrophysics Data System (ADS)
DeVorkin, David
2012-09-01
Of all the known observable characteristics of the stars in the late 19th Century, classification by the appearance of their spectra was by far the most problematic. In 1904, Edwin Frost lamented that some 23 distinct classification systems had been created, yet none were universally accepted. In 1908, the applied mathematician Karl Pearson and a student evaluated correlations between spectra and other characteristics of the stars, hoping to ``look upon the stellar universe as an orderly whole ... by which we pass from chaos to an organised and locally differentiated cosmos.'' None of the major spectral systems, however, allowed them to draw any conclusions, other than state a high correlation with color. Yet, by 1917, astronomers were making correlations, and applying them, to make some pretty strong statements about the nature and history of the sidereal system as well as the lives of the stars. One of the strongest was the technique of spectroscopic parallaxes. But even its discoverer, Walter Sydney Adams, worried about what it all meant. Writing to Eddington in 1917, Adams wished that ``we had more physical knowledge regarding the interpretations of stellar spectra.'' And as E. A. Milne observed some years later, in retrospect, ``[t]here was a gap in the logical argument.'' My talk will address some historiographical issues arising from this phase in the development of modern astrophysics that hopefully will illuminate why the gap was closed in the way it was closed, and the effect it had on the continuing process of spectral classification.
Distinctive Clinical Correlates of Psychotic Major Depression: The CRESCEND Study
Park, Seon-Cheol; Lee, Hwa-Young; Sakong, Jeong-Kyu; Jun, Tae-Youn; Lee, Min-Soo; Kim, Jae-Min; Kim, Jung-Bum; Yim, Hyeon-Woo
2014-01-01
Objective The purpose of this investigation was to identify distinctive clinical correlates of psychotic major depression (PMD) as compared with non-psychotic major depression (NPMD) in a large cohort of Korean patients with major depressive disorder (MDD). Methods We recruited 966 MDD patients of age over 18 years from the Clinical Research Center for Depression of South Korea (CRESCEND) study. Diagnoses of PMD (n=24) and NPMD (n=942) were made with the DSM-IV definitions and confirmed with SCID. Psychometric scales were used to assess overall psychiatric symptoms (BPRS), depression (HAMD), anxiety (HAMA), global severity (CGI-S), suicidal ideation (SSI-Beck), functioning (SOFAS), and quality of life (WHOQOL-BREF). Using independent t-tests and ?2 tests, we compared clinical characteristics of patients with PMD and NPMD. A binary logistic regression model was constructed to identify factors independently associated with increased likelihood of PMD. Results PMD subjects were characterized by a higher rate of inpatient enrollment, and higher scores on many items on BPRS (somatic concern, anxiety, emotional withdrawal, guilt feelings, tension, depression, suspiciousness, hallucination, motor retardation, blunted affect and excitement) global severity (CGI-s), and suicidal ideation (SSI-Beck). The explanatory factor model revealed that high levels of tension, excitement, and suicidal ideation were associated with increased likelihood of PMD. Conclusion Our findings partly support the view that PMD has its own distinctive clinical manifestation and course, and may be considered a diagnostic entity separate from NPMD. PMID:25110501
Magnitude correlations in global seismicity
Sarlis, N. V.
2011-08-15
By employing natural time analysis, we analyze the worldwide seismicity and study the existence of correlations between earthquake magnitudes. We find that global seismicity exhibits nontrivial magnitude correlations for earthquake magnitudes greater than M{sub w}6.5.
Anglin, R E; Rosebush, P I; Noseworthy, M D; Tarnopolsky, M; Mazurek, M F
2012-01-01
There is increasing recognition that mitochondrial dysfunction may have a critical role in the pathophysiology of major psychiatric illnesses. Patients with mitochondrial disorders offer a unique window through which we can begin to understand the association between psychiatric symptoms and mitochondrial dysfunction in vivo. Using proton magnetic resonance spectroscopy (1H-MRS), we investigated metabolic indices in mitochondrial patients in regions of the brain that have been implicated in psychiatric illness: the caudate, cingulate cortex and hippocampus. In all, 15 patients with mitochondrial disorders and 15 age- and sex-matched controls underwent a comprehensive psychiatric assessment, including the administration of standardized psychiatric rating scales, followed by single voxel 1H-MRS of the caudate, cingulate cortex and hippocampus to measure N-acetyl aspartate (NAA), creatine (Cr), glycerophosphocholine (GPC), myoinositol and glutamate+glutamine (Glx). Pearson's correlation coefficients were used to determine correlations between metabolites and the psychiatric rating scales. Anxiety symptoms in these patients correlated with higher GPC, Glx, myoinositol and Cr in the hippocampus. Impaired level of function as a result of psychiatric symptoms correlated with higher Glx and GPC in the cingulate cortex. In summary, we found remarkably consistent, and statistically significant, correlations between anxiety and metabolic indices in the hippocampus in patients with mitochondrial disorders, while overall impairment of functioning due to psychiatric symptoms correlated with metabolic markers in the cingulate cortex. These findings lend support to the notion that mitochondrial dysfunction in specific brain regions can give rise to psychiatric symptoms. In particular, they suggest that metabolic processes in the hippocampus may have an important role in the neurobiology of anxiety. PMID:23149451
A correlation between hard gamma-ray sources and cosmic voids along the line of sight
Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.
2014-11-25
We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as â€śVHE-likeâ€ť sources) are distributed along underdense lines of sight at the 2.4Ď level. There is a less suggestive correlation for the Fermi hard source population (1.7Ď). A correlation between 10-500 GeV flux and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4Ď and 2.6Ď, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity Ď„(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.
Correlation between BOLD-MRI and HIF expression level in renal carcinoma
Li, Dong; Wang, Xingming; Wang, Shuai; Cheng, Jie
2015-01-01
Occupying about 2%~3% of all malignant tumors, renal carcinoma is the most common primary cancer in kidney. The oxidative level of tumor cells is of vital role for optimizing treatment plan, evaluating efficacy and predicting prognosis. This study thus investigated the R2* value in mouse renal carcinoma model and the correlation between tumor hypoxia and expression level of hypoxia inducible factor-1 (HIF-1). A total of 20 BALB/C nude mice (4~6 weeks old) were inoculated with human ACHN renal carcinoma cells to generate renal cancer model. After the tumor diameter reached 0.5 cm, all animals were examined by BOLD-MRI, both under normal inhalation (R2a*) and carbogen treatment (R2b*). The alternation of R2* values (?R2*=R2a* - R2b*) was calculated. Mice were then sacrificed for Immunohistochemical (IHC) staining targeting HIF-1? and HIF-2?. The positive score of HIF was then analyzed for its correlation with R2* value. In 18 mice finished both experiments, Pearson correlation analysis revealed significant negative correlation between R2a* and ?R2* (r=-0.48, P<0.05) and positive relationship between ?R2* and HIF-2? (r=0.38, P<0.05). HIF-1? level, however, did not correlated with tumor R* values. The positive correlation between ?R2* and HIF-2?, but not HIF-1?, suggested potential role of combined BOLD-MRI technique and HIF-1? staining in clinical diagnosis of renal carcinoma. HIF-2? may work as biological marker for renal cancer. PMID:26722605
A correlation between hard gamma-ray sources and cosmic voids along the line of sight
Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.
2014-11-25
We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as â€śVHE-likeâ€ť sources) are distributed along underdense lines of sight at the 2.4Ď level. There is a less suggestive correlation for the Fermi hard source population (1.7Ď). A correlation between 10-500 GeV fluxmoreÂ Â» and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4Ď and 2.6Ď, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity Ď„(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.Â«Â less
Anglin, R E; Rosebush, P I; Noseworthy, M D; Tarnopolsky, M; Mazurek, M F
2012-01-01
There is increasing recognition that mitochondrial dysfunction may have a critical role in the pathophysiology of major psychiatric illnesses. Patients with mitochondrial disorders offer a unique window through which we can begin to understand the association between psychiatric symptoms and mitochondrial dysfunction in vivo. Using proton magnetic resonance spectroscopy ((1)H-MRS), we investigated metabolic indices in mitochondrial patients in regions of the brain that have been implicated in psychiatric illness: the caudate, cingulate cortex and hippocampus. In all, 15 patients with mitochondrial disorders and 15 age- and sex-matched controls underwent a comprehensive psychiatric assessment, including the administration of standardized psychiatric rating scales, followed by single voxel (1)H-MRS of the caudate, cingulate cortex and hippocampus to measure N-acetyl aspartate (NAA), creatine (Cr), glycerophosphocholine (GPC), myoinositol and glutamate+glutamine (Glx). Pearson's correlation coefficients were used to determine correlations between metabolites and the psychiatric rating scales. Anxiety symptoms in these patients correlated with higher GPC, Glx, myoinositol and Cr in the hippocampus. Impaired level of function as a result of psychiatric symptoms correlated with higher Glx and GPC in the cingulate cortex. In summary, we found remarkably consistent, and statistically significant, correlations between anxiety and metabolic indices in the hippocampus in patients with mitochondrial disorders, while overall impairment of functioning due to psychiatric symptoms correlated with metabolic markers in the cingulate cortex. These findings lend support to the notion that mitochondrial dysfunction in specific brain regions can give rise to psychiatric symptoms. In particular, they suggest that metabolic processes in the hippocampus may have an important role in the neurobiology of anxiety. PMID:23149451
Correlation Between Vision and Cognitive Function in the Elderly: A Cross-Sectional Study.
Spierer, Oriel; Fischer, Naomi; Barak, Adiel; Belkin, Michael
2016-01-01
The correlation between vision and cognition is not fully understood. Visual impairment in the elderly has been associated with impaired cognitive function, dementia, and Alzheimer disease. The aim was to study the correlation between near visual acuity (VA), refraction, and cognitive state in an elderly population.Subjects ?75 years were enrolled in this cross-sectional study. Refraction and near VA was tested. Cognitive function was evaluated with a version of the mini-mental state examination for the visually impaired (MMSE-blind). The eye with better VA and no cataract or refractive surgery was analyzed.One-hundred ninety subjects (81.6?±?5.1 years, 69.5% female) were included. Good VA (?J3) was associated with high MMSE-blind (>17) (OR?=?3.18, 95% CI?=?1.57-6.43, P?=?0.001). This remained significant adjusting for sex, age, and years of education. Wearing reading glasses correlated significantly with high MMSE-blind after adjustment for sex and age (OR?=?2.14, 95% CI?=?1.16-3.97, P?=?0.016), but reached borderline significance after adjustment for education. There was a trend toward correlation between myopia and better MMSE-blind (r?=?-0.123, P?=?0.09, Pearson correlation).Good VA and wearing glasses seem to correlate with better cognitive function. Reading glasses can serve as a protective factor against cognitive deterioration associated with sensory (visual) deprivation in old age. The association between myopia and cognition requires further investigation. PMID:26817872
Gangwani, Rita A.; Lee, Jacky W.Y.; Mo, H.Y.; Sum, Rita; Kwong, Alfred S.K.; Wang, Jenny H.L.; Tsui, Wendy W.S.; Chan, Jonathan C.H.; Lai, Jimmy S.M.
2015-01-01
Abstract To investigate the association between retinal nerve fiber layer (RNFL) thickness and blood pressure (BP) in subjects with systemic hypertension. Subjects with systemic hypertension on anti-hypertensive medications were screened by fundus photography and referred for glaucoma work-up if there was enlarged vertical cup-to-disc (VCDR) ratio ?0.6, VCDR asymmetry ?0.2, or optic disc hemorrhage. Workup included a complete ophthalmological examination, Humphrey visual field test, and RNFL thickness measurement by optical coherence tomography. The intraocular pressure (IOP) and RNFL thicknesses (global and quadrant) were averaged from both eyes and the means were correlated with: the systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) using Pearson correlation. Among 4000 screened hypertensive subjects, 133 were referred for glaucoma workup and 110 completed the workup. Of the 4000 screened subjects, 1.3% had glaucoma (0.9% had normal tension glaucoma [NTG], 0.2% had primary open angle glaucoma, and 0.2% had primary angle closure glaucoma), whereas 0.3% were NTG suspects. The SBP was negatively correlated with the mean superior RNFL thickness (P?=?0.01). The DBP was negatively correlated with the mean global (P?=?0.03), superior (P?=?0.02), and nasal (P?=?0.003) RNFL thickness. The MAP was negatively correlated with the mean global (P?=?0.01), superior (P?=?0.002), and nasal (P?=?0.004) RNFL thickness while positively correlated with the mean IOP (P?=?0.02). In medically treated hypertensive subjects, glaucoma was present in 1.3%, with NTG being most prevalent. MAP control may help with IOP lowering and RNFL preservation, although future prospective studies will be needed. PMID:26061324
NASA Astrophysics Data System (ADS)
Curme, Chester
Technological advances have provided scientists with large high-dimensional datasets that describe the behaviors of complex systems: from the statistics of energy levels in complex quantum systems, to the time-dependent transcription of genes, to price fluctuations among assets in a financial market. In this environment, where it may be difficult to infer the joint distribution of the data, network science has flourished as a way to gain insight into the structure and organization of such systems by focusing on pairwise interactions. This work focuses on a particular setting, in which a system is described by multivariate time series data. We consider time-lagged correlations among elements in this system, in such a way that the measured interactions among elements are asymmetric. Finally, we allow these interactions to be characteristically weak, so that statistical uncertainties may be important to consider when inferring the structure of the system. We introduce a methodology for constructing statistically validated networks to describe such a system, extend the methodology to accommodate interactions with a periodic component, and show how consideration of bipartite community structures in these networks can aid in the construction of robust statistical models. An example of such a system is a financial market, in which high frequency returns data may be used to describe contagion, or the spreading of shocks in price among assets. These data provide the experimental testing ground for our methodology. We study NYSE data from both the present day and one decade ago, examine the time scales over which the validated lagged correlation networks exist, and relate differences in the topological properties of the networks to an increasing economic efficiency. We uncover daily periodicities in the validated interactions, and relate our findings to explanations of the Epps Effect, an empirical phenomenon of financial time series. We also study bipartite community structures in networks composed of market returns and news sentiment signals for 40 countries. We compare the degrees to which markets anticipate news, and news anticipate markets, and use the community structures to construct a recommender system for inputs to prediction models. Finally, we complement this work with novel investigations of the exogenous news items that may drive the financial system using topic models. This includes an analysis of how investors and the general public may interact with these news items using Internet search data, and how the diversity of stories in the news both responds to and influences market movements.
Canonical Correlation: Terms and Descriptions.
ERIC Educational Resources Information Center
Pugh, Richard C.; Hu, Yuehluen
The use of terms to describe and interpret results from canonical correlation analysis has been inconsistent across research studies. This study assembled the terminology related to the use and interpretation of canonical correlation analysis from research articles, textbooks, and computer manuals. Research articles using canonical correlation…
Correlations in coherent multiple scattering
NASA Astrophysics Data System (ADS)
Berkovits, Richard; Feng, Shechao
1994-03-01
We present details of calculations and a comprehensive review on the various correlation functions for coherent electronic or classical wave transmission through a disordered scattering medium, in the diffusive limit ? ? l? ? L?, where ? is the wavelength, l? is the transport mean free path, and L? is the phase coherence length. The connection between mesoscopic conductance fluctuations in disordered metals and speckle pattern fluctuations for classical waves is reviewed. The short-range correlation function C(1) is shown to be responsible for the conventional speckle pattern fluctuations and the so called “memory effect”. The long-range correlation function C(2) is shown to dominate in the correlations and fluctuations of the total transmission coefficient. The “infinite range” background correlation function C(3) is shown to be related to the universal conductance fluctuations in disordered mesoscopic conductors. We also discuss many generalized correlation functions such as those for frequency correlations, spatial correlations, correlations in Fabry-Perot interferometer devices, and in reflection geometries. A special kind of correlation function, corresponding to the sensitivity of speckle pattern intensities to the motion of impurities, will also be reviewed. Finally, the equivalence between the angular correlation functions and the auto-correlation functions in “diffusing wave spectroscopy” will be discussed.
Kumar, Dharmendra; Ahmed, Syed Moied; Ali, Shahna; Ray, Utpal; Varshney, Ankur; Doley, Kashmiri
2015-01-01
Background: Central venous pressure (CVP) assesses the volume status of patients. However, this technique is not without complications. We, therefore, measured peripheral venous pressure (PVP) to see whether it can replace CVP. Aims: To evaluate the correlation and agreement between CVP and PVP after passive leg raise (PLR) in critically ill patients on mechanical ventilation. Setting and Design: Prospective observational study in Intensive Care Unit. Methods: Fifty critically ill patients on mechanical ventilation were included in the study. CVP and PVP measurements were taken using a water column manometer. Measurements were taken in the supine position and subsequently after a PLR of 45°. Statistical Analysis: Pearson's correlation and Bland–Altman's analysis. Results: This study showed a fair correlation between CVP and PVP after a PLR of 45° (correlation coefficient, r = 0.479; P = 0.0004) when the CVP was <10 cmH2O. However, the correlation was good when the CVP was >10 cmH2O. Bland–Altman analysis showed 95% limits of agreement to be ?2.912–9.472. Conclusion: PVP can replace CVP for guiding fluid therapy in critically ill patients. PMID:26730115
Chikamatsu, Kinuyo; Aono, Akio; Kato, Tomoko; Takaki, Akiko; Yamada, Hiroyuki; Sasaki, Yuka; Izumi, Kiyohiko; Yi, Lina; Mitarai, Satoshi
2016-01-01
We investigated the correlation between the cycle threshold (Ct) value of the COBAS(®) TaqMan(®) MTB (TaqMan MTB), the mycobacterial smear positivity grade, and the time to detection (TTD) in the Mycobacteria Growth Indicator Tube (MGIT) for quantification of Mycobacterium tuberculosis (MTB). For 57 sputum samples, significant correlations were observed between the Ct value, the smear positivity grade, and the MGIT TTD (Spearman's rank correlation coefficient: rs = -0.940, P < 0.001 and Pearson's correlation coefficient: rp = 0.737, P < 0.001). In addition, a correlation was observed between the number of bacteria estimated based on the smear positivity grade and the number of MTB bacilli calculated by the Ct value (rs = 0.930, P < 0.001). This study has demonstrated the possible estimation of the smear positivity grade and MGIT TTD using the Ct value of TaqMan MTB, which is based on a real-time PCR system, for diagnostic samples. PMID:26527538
Li, Yuanmin; Xiao, Qiang; Zeng, Wei; Guo, Huimei; Jiang, Ke; Zhong, Ming; Zhong, Jingquan
2015-01-01
Abstract To investigate the relationship between red blood cell distribution width (RDW) and diurnal corrected QT (QTc) variation in patients with coronary heart disease. This retrospective study included 203 patients who underwent coronary angiography between February 2013 and June 2014. RDW values and dynamic electrocardiography (Holter) results were collected to investigate the relationship between RDW and diurnal QTc variation. Patients were separated into three groups (A, B, and C) by binning their RDW values in an ascending order. RDW values, coronary artery scores and diurnal QTc variations were significantly different among these groups (Pâ€Š<â€Š0.05). While coronary artery scores gradually rose with increased RDW, diurnal QTc variation decreased. Pearson's correlation analysis was applied to control for confounding factors, and multiple correlation analysis showed that coronary artery score was positively correlated with RDW (râ€Š=â€Š0.130, Pâ€Š=â€Š0.020), while it was not correlated with the diurnal QTc variation (râ€Š=â€Šâ’0.226, Pâ€Š=â€Š0.681). RDW was negatively correlated with diurnal QTc variation (râ€Š=â€Šâ’0.197, Pâ€Š=â€Š0.035). RDW is independently associated with diurnal QTc variation in patients with coronary heart disease. PMID:26061304
Bresciani-Battilana, Erica; Teixeira, Ivan C; Barbosa, Diego T Q; Caixeta-Umbelino, Cristiano; Paolera, Maurício D; Kasahara, Niro
2015-10-01
To correlate the ganglion cell complex (GCC) parameters with structural measures of the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) as evaluated by Fourier-Domain optic coherence tomography (OCT). This retrospective study included patients with glaucoma, ocular hypertensive patients and glaucoma suspects who had previously undergone OCT examination with the RTVue-100. The parameters of GCC (average, superior, inferior, focal loss volume [FLV], global loss volume [GLV]) were correlated with the values of the ONH (cup volume, cup area, horizontal cup-to-disk ratio, vertical cup-to-disk ratio, and rim area) and RNFL (average, superior, and inferior) using Pearson's correlation coefficient. The sample included 74 eyes of 37 patients. All correlations between GCC parameters and RNFL were strong (r > 0.60). The correlation between GCC parameters and ONH were good for most parameters, except that for FLV and cup volume (r = 0.13), GLV and cup volume (r = 0.09), and GLV and cup area (r = 0.21). The GCC parameters can be used as structural measures of the glaucomatous optic neuropathy. PMID:25183459
Becker, A-C; Stock, K F; Distl, O
2013-01-01
New movement traits reflecting unfavorable movement characteristics were defined on the basis of detailed movement evaluations (DME) of warmblood foals and mares performed in connection with regular breeding events of the Oldenburg horse breeding societies in 2009 and 2010. DME information was available for 3374 foals and 2844 mares and used for correlation analyses with conformation information on 1987 mares from studbook inspections (SBI) in 2009 and performance information on 2758 mares from mare performance tests (MPT) in 2000 to 2008. Analyses of variance revealed few significant differences between scores for SBI and MPT traits in mares without and with indications of imbalance (IMB) in general or specific findings like irregular tail tone or posture (TTP). SBI scores for general impression and development were significantly lower and MPT scores for trot under rider tended to be higher in IMB-positive mares. Genetic parameters were estimated in linear animal models with residual maximum likelihood. Additive genetic correlations and Pearson correlation coefficients between univariately predicted breeding values indicated unfavorable genetic correlations of IMB and TTP with dressage-related conformation and performance traits. For SBI and MPT traits, we found similarities between the correlation patterns for DME traits in foals and mares. The results implied that breeding of dressage horses may benefit from revision of current movement evaluation and consideration of specific movement characteristics. PMID:23031204
Zhang, Yanyan; Wang, Bei; Zhou, Cunshan; Atungulu, Griffiths G; Xu, Kangkang; Ma, Haile; Ye, Xiaofei; Abdualrahman, Mohammed A Y
2016-07-01
The effects of alternate dual-frequency ultrasound (ADFU) pretreatment on the degree of hydrolysis (DH) of wheat gluten (WG) and angiotensin I-converting enzyme (ACE) inhibitory activity were investigated in this research. The surface topography, nano-mechanics and secondary structure of WG were also determined using atomic force microscope (AFM) and circular dichroism (CD). The correlations of ACE inhibitory activity and DH with surface topography, nano-mechanics and secondary structure of WG were determined using Pearson's correlation analysis. The results showed that with an increase in either pretreatment duration or power, the ACE inhibitory activity of the hydrolysate also increases, reaching maximum at 10min and 150W/L, respectively, and then decreases thereafter. Similarly, AFM analysis showed that as the pretreatment duration or power increases, the surface roughness also increase and again a decrease occurs thereafter. As the pretreatment duration or power increased, the Young's modulus and adhesion of WG also increased and then declined. Young's modulus and adhesions average values were compared with ACE inhibitory activity reversely. The result of the CD spectra analysis exhibited losses in the relative percentage of Î±-helix of WG. Pearson's correlation analysis showed that the average values of Young's modulus and the relative percentage of Î±-helix correlated with ACE inhibitory activity of the hydrolysates linearly and significantly (P<0.05); the relative percentage of Î˛-sheet correlated linearly with DH of WG significantly (P<0.05). In conclusion, ADFU pretreatment is an efficient method in proteolysis due to its physical and chemical effect on the Young's modulus, Î±-helix and Î˛-sheet of WG. PMID:26964949
Correlational effect size benchmarks.
Bosco, Frank A; Aguinis, Herman; Singh, Kulraj; Field, James G; Pierce, Charles A
2015-03-01
Effect size information is essential for the scientific enterprise and plays an increasingly central role in the scientific process. We extracted 147,328 correlations and developed a hierarchical taxonomy of variables reported in Journal of Applied Psychology and Personnel Psychology from 1980 to 2010 to produce empirical effect size benchmarks at the omnibus level, for 20 common research domains, and for an even finer grained level of generality. Results indicate that the usual interpretation and classification of effect sizes as small, medium, and large bear almost no resemblance to findings in the field, because distributions of effect sizes exhibit tertile partitions at values approximately one-half to one-third those intuited by Cohen (1988). Our results offer information that can be used for research planning and design purposes, such as producing better informed non-nil hypotheses and estimating statistical power and planning sample size accordingly. We also offer information useful for understanding the relative importance of the effect sizes found in a particular study in relationship to others and which research domains have advanced more or less, given that larger effect sizes indicate a better understanding of a phenomenon. Also, our study offers information about research domains for which the investigation of moderating effects may be more fruitful and provide information that is likely to facilitate the implementation of Bayesian analysis. Finally, our study offers information that practitioners can use to evaluate the relative effectiveness of various types of interventions. PMID:25314367
Frontotemporal Dementia: Clinicopathological Correlations
Forman, Mark S.; Farmer, Jennifer; Johnson, Julene K.; Clark, Christopher M.; Arnold, Steven E.; Coslett, H. Branch; Chatterjee, Anjan; Hurtig, Howard I.; Karlawish, Jason H.; Rosen, Howard J.; Van Deerlin, Vivianna; Lee, Virginia M.-Y.; Miller, Bruce L.; Trojanowski, John Q.; Grossman, Murray
2009-01-01
Objective Frontotemporal lobar degeneration (FTLD) is characterized by impairments in social, behavioral, and/or language function, but postmortem studies indicate that multiple neuropathological entities lead to FTLD. This study assessed whether specific clinical features predict the underlying pathology. Methods A clinicopathological correlation was performed on 90 consecutive patients with a pathological diagnosis of frontotemporal dementia and was compared with an additional 24 cases accrued during the same time period with a clinical diagnosis of FTLD, but with pathology not typically associated with frontotemporal dementia. Results Postmortem examination showed multiple pathologies including tauopathies (46%), FTLD with ubiquitin-positive inclusions (29%), and Alzheimerâ€™s disease (17%). The pathological groups manifested some distinct demographic, clinical, and neuropsychological features, although these attributes showed only a statistical association with the underlying pathology. FTLD with ubiquitin-positive inclusions was more likely to present with both social and language dysfunction, and motor neuron disease was more likely to emerge in these patients. Tauopathies were more commonly associated with an extrapyramidal disorder. Alzheimerâ€™s disease was associated with relatively greater deficits in memory and executive function. Interpretation Clinical and neuropsychological features contribute to delineating the spectrum of pathology underlying a patient diagnosed with FTLD, but biomarkers are needed that, together with the clinical phenotype, can predict the underlying neuropathology. PMID:16718704
Direct measure of quantum correlation
Yu, Chang-shui; Zhao, Haiqing
2011-12-15
The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present a direct measure of quantum correlation by revealing the difference between the structures of classically and quantum correlated states. Our measure explicitly includes the contributions of the inseparability and local nonorthogonality of the eigenvectors of a density matrix. Besides its relatively easy computability, our measure can provide a unified understanding of quantum correlation of all the present versions.
ERIC Educational Resources Information Center
Prevost, A. Toby; Mason, Dan; Griffin, Simon; Kinmonth, Ann-Louise; Sutton, Stephen; Spiegelhalter, David
2007-01-01
Practical meta-analysis of correlation matrices generally ignores covariances (and hence correlations) between correlation estimates. The authors consider various methods for allowing for covariances, including generalized least squares, maximum marginal likelihood, and Bayesian approaches, illustrated using a 6-dimensional response in a series of…
More Voodoo correlations: when average-based measures inflate correlations.
Brand, Andrew; Bradley, Michael T
2012-01-01
A Monte-Carlo simulation was conducted to assess the extent that a correlation estimate can be inflated when an average-based measure is used in a commonly employed correlational design. The results from the simulation reveal that the inflation of the correlation estimate can be substantial, up to 76%. Additionally, data was re-analyzed from two previously published studies to determine the extent that the correlation estimate was inflated due to the use of an averaged based measure. The re-analyses reveal that correlation estimates had been inflated by just over 50% in both studies. Although these findings are disconcerting, we are somewhat comforted by the fact that there is a simple and easy analysis that can be employed to prevent the inflation of the correlation estimate that we have simulated and observed. PMID:24837177
Correlations of correlations: Secondary autocorrelations in finite harmonic systems.
Plyukhin, Dan; Plyukhin, Alex V
2015-10-01
The momentum or velocity autocorrelation function C(t) for a tagged oscillator in a finite harmonic system decays like that of an infinite system for short times, but exhibits erratic behavior at longer time scales. We introduce the autocorrelation function of the long-time noisy tail of C(t) ("a correlation of the correlation"), which characterizes the distribution of recurrence times. Remarkably, for harmonic systems with same-mass particles this secondary correlation may coincide with the primary correlation C(t) (when both functions are normalized) either exactly, or over a significant initial time interval. When the tagged particle is heavier than the rest, the equality does not hold, correlations show nonrandom long-time scale pattern, and higher-order correlations converge to the lowest normal mode. PMID:26565162
Marques, Carla Couzi; da Penha Zago-Gomes, Maria; Gonçalves, Carlos Sandoval; Pereira, Fausto Edmundo Lima
2010-01-01
Background Significantly higher prevalence of Strongyloides stercoralis has been reported in chronic alcoholic patients. The aim of this investigation was to report the prevalence of Strongyloides larvae in stools of chronic alcoholic patients with known daily ethanol intake. Methods From January 2001 through December 2003 the results of fecal examinations and the daily ethanol intake were retrieved from the records of 263 chronic alcoholic and from 590 non-alcoholic male patients that sought health care at the outpatients unit of the University Hospital C A Moraes. Alcoholic patients were separated into four groups, with 150g intervals between the groups according to the daily ethanol intake. Results (a) The frequency of Strongyloides was significantly higher in alcoholic patients than in control group (overall prevalence in alcoholic 20.5% versus 4.4% in control group; p?=?0.001). Even in the group with a daily intake of ethanol equal to or less than 150g the prevalence was higher than in control group, although non significant (9.5%, versus 4.4% in control group; p?=?0,071); (b) the prevalence of Strongyloides in alcoholic patients rises with the increase of ethanol intake (Pearson's Correlation Coefficient?=?0.956; p?=?0.022), even in patients without liver cirrhosis (Pearson's Correlation Coefficient?=?0.927; p?=?0.037). Conclusion These results confirm and reinforce the hypothesis that chronic alcoholism is associated with Strongyloides infection, which is in direct relationship with the severity of alcoholism, independently of the presence of liver cirrhosis. PMID:20582163
Stoker, C; Repetti, M R; García, S R; Zayas, M A; Galoppo, G H; Beldoménico, H R; Luque, E H; Muńoz-de-Toro, M
2011-06-01
Organochlorine compounds (OCCs), like pesticides (OCPs) and polychlorinated biphenyls (PCBs), are persistent lipophilic chemicals classified as endocrine-disruptors. Caiman latirostris inhabits wetlands throughout north-eastern Argentina and may accumulate OCCs. The aims of this study were to determine OCC residues in the eggs of C. latirostris and to correlate OCC burden with clutch size, hatching success and hatchling survival as measures of reproductive performance. Fourteen caiman clutches were harvested from sites with different degrees of anthropogenic intervention on wetlands surrounding Paraná River tributaries. Two to four eggs by clutch were used to quantify OCCs. OCP residues were found in all clutches. The principal contributors to the OCPs burden were the DDT family (range BDL-153.0 ng g(-1) lipid) and oxychlordane (range BDL-34.3 ng g(-1) lipid). PCBs were present in 92.9% of the clutches (range BDL-136.6 ng g(-1) lipid). Both higher concentrations and higher diversity of pesticides, including endosulfan sulfate, were found in the nests harvested close to croplands. A negative correlation was found between clutch size and ?OCCs (p=0.02, Pearson r=-0.53, r(2)=0.28), mainly due to the ?OCPs (p=0.04, Pearson r=-0.54, r(2)=0.30). Since egg OCCs concentrations predict maternal burden, present findings suggest that higher OCCs exposure could lead to smaller clutches. Although, other factors like mother age could influence clutch size. Additionally, as caimans are a long-lived and non-migratory species, the maternal OCCs burden reflects the environmental status throughout their home range; thus, caiman eggs could be useful as a biomonitor of local contamination. PMID:21531435
Lidfeldt, Jon; Bendahl, Pär-Ola; Forsare, Carina; Malmström, Per; Fernö, Mĺrten; Belting, Mattias
2015-01-01
Experimental models implicate protease activated receptors (PARs) as important sensors of the proteolytic tumor microenvironment during breast cancer development. However, the role of the major PARs, PAR-1 and PAR-2, in human breast tumors remains to be elucidated. Here, we have investigated how PAR-1 and PAR-2 protein expression correlate with established clinicopathological variables and patient outcome in a well-characterized cohort of 221 breast cancer patients. Univariable and multivariable hazard ratios (HR) were estimated by the Cox proportional hazards model, distant disease-free survival (DDFS) and overall survival by the Kaplan–Meier method, and survival in different strata was determined by the log-rank test. Associations between PARs and clinicopathological variables were analyzed using Pearson’s ?2-test. We find that PAR-2 associates with DDFS (HR = 3.1, P = 0.003), whereas no such association was found with PAR-1 (HR = 1.2, P = 0.6). Interestingly, the effect of PAR-2 was confined to the ER-positive sub-group (HR = 5.5, P = 0.003 vs. HR = 1.2 in ER-negative; P = 0.045 for differential effect), and PAR-2 was an independent prognostic factor specifically in ER-positive tumors (HR = 3.9, P = 0.045). On the contrary, PAR-1 correlated with worse prognosis specifically in the ER-negative group (HR = 2.6, P = 0.069 vs. HR = 0.5, P = 0.19 in ER-positive; P = 0.026 for differential effect). This study provides novel insight into the respective roles of PAR-1 and PAR-2 in human breast cancer and suggests a hitherto unknown association between PARs and ER signaling that warrants further investigation. PMID:26244666
Correlation Analysis between Tibet AS-? TeV Cosmic Ray and WMAP Nine-year Data
NASA Astrophysics Data System (ADS)
Yin, Qian-Qing; Zhang, Shuang-Nan
2015-08-01
The WMAP team subtracted template-based foreground models to produce foreground-reduced maps, and masked point sources and uncertain sky regions directly; however, whether foreground residuals exist in the WMAP foreground-reduced maps is still an open question. Here, we use Pearson correlation coefficient analysis with AS-? TeV cosmic ray (CR) data to probe possible foreground residuals in the WMAP nine-year data. The correlation results between the CR and foreground-contained maps (WMAP foreground-unreduced maps, WMAP template-based, and Maximum Entropy Method foreground models) suggest that: (1) CRs can trace foregrounds in the WMAP data; (2) at least some TeV CRs originate from the Milky Way; (3) foregrounds may be related to the existence of CR anisotropy (loss-cone and tail-in structures); (4) there exist differences among different types of foregrounds in the decl. range of <15°. Then, we generate 10,000 mock cosmic microwave background (CMB) sky maps to describe the cosmic variance, which is used to measure the effect of the fluctuations of all possible CMB maps to the correlations between CR and CMB maps. Finally, we do correlation analysis between the CR and WMAP foreground-reduced maps, and find that: (1) there are significant anticorrelations; and (2) the WMAP foreground-reduced maps are credible. However, the significant anticorrelations may be accidental, and the higher signal-to-noise ratio Planck SMICA map cannot reject the hypothesis of accidental correlations. We therefore can only conclude that the foreground residuals exist with ?95% probability.
Impact and correlation of environmental conditions on pollen counts in Karachi, Pakistan.
Perveen, Anjum; Khan, Muneeba; Zeb, Shaista; Imam, Asif Ali
2015-02-01
A quantitative and qualitative survey of airborne pollen was performed in the city of Karachi, and the pollen counts were correlated with different climatic conditions. The aim of the study was to determine the possible effect of meteorological factors on airborne pollen distribution in the atmosphere of Karachi city. Pollen sampling was carried out by using Burkard spore Trap for the period of August 2009 to July 2010, and a total of 2,922 pollen grains/m(3) were recorded. In this survey, 22 pollen types were recognized. The highest pollen count was contributed by Poaceae pollen type (1,242 pollen grains/m(3)) followed by Amaranthaceae/Chenopodiaceae (948 pollen grains/m(3)), Cyperus rotundus (195 pollen grains/m(3)) and Prosopis juliflora (169 pollen grains/m(3)). Peak pollen season was in August showing a total of 709 pollen grains/m(3) and lowest pollen count was observed in January-2010. Pearson's chi-square test was performed for the possible correlation of pollen counts and climatic factors. The test revealed significant positive correlation of wind speed with pollen types of Amaranthaceae/Chenopodiaceae; Brassica campestris; Asteraceae; and Thuja orientalis. While the correlation of "average temperature" showed significant positive value with Asteraceae and Tamarix indica pollen types. Negative correlation was observed between humidity/ precipitation and pollen types of Brassica campestris; Daucus carota; Ephedra sp.; and Tamarix indica. In the light of above updated data one could identify various aeroallergens present in the air of Karachi city. PMID:25530143
Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?
Love, J.J.; Mursula, K.; Tsai, V.C.; Perkins, D.M.
2011-01-01
Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868-2008, solar cycles 11-23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically- significant correlation between sunspot number and geomagnetic activity, Pearson p < 10-4, but correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction. ?? 2011 by the American Geophysical Union.
Ă–zdemir, GĂĽlsĂĽn; Kaya, Hatice
2013-01-01
Background: Methods learnt by nursing and midwifery studentsâ€™ such as communication skills, optimisim and coping with stress would be used in their profeesional life. It is very important to promote their positive thinking and communication skills to raise coping with stress. Objectives: This cross sectional study was performed to examine the nursing and midwifery studentsâ€™ communication skills and optimistic life orientation and its correlation with coping strategies with stress. Materials and Methods: The study population included 2572 students who were studying in departments of nursing and midwifery in Istanbul. The sample was included 1419 students. Three questionnaires including Communication Skills Test, Life Orientation Test and Ways of Coping Inventory were used for data collection. The data were evaluated by calculating frequency, percentage, arithmetic mean, standard deviation and Pearson correlation coefficient. Results: Studentsâ€™ total mean score from the Communication Skills Scale was 165.27 Â± 15.39 and for the Life Orientation Test was 18.51 Â± 4.54. There was a positive correlation between their Life Orientation scores and the scores for self confidence (r = 0.34, P < 0.001), optimistic approach (r = 0.42, P < 0.001), and seeking social help (r = 0.17, P < 0.001). Also there was a significant positive correlation between Communication skill scores and self confidence (r = 0.46, P < 0.001), optimistic (r = 0.37, P < 0.001) and seeking social help approaches (r = 0.29, P < 0.001), but there was a significant negative correlation between communication skill scores and scores for helpless (r = -0.29, P < 0.001) and submissive approaches (r = -0.36, P < 0.001). Conclusions: As scores of students in optimistic life orientation and communication skills increased self confidence approach, optimistic, and social support seeking scores increased, whereas helpless, and submissive scores decreased. PMID:25414859
SAW correlator spread spectrum receiver
Brocato, Robert W
2014-04-01
A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.
Image correlation and sampling study
NASA Technical Reports Server (NTRS)
Popp, D. J.; Mccormack, D. S.; Sedwick, J. L.
1972-01-01
The development of analytical approaches for solving image correlation and image sampling of multispectral data is discussed. Relevant multispectral image statistics which are applicable to image correlation and sampling are identified. The general image statistics include intensity mean, variance, amplitude histogram, power spectral density function, and autocorrelation function. The translation problem associated with digital image registration and the analytical means for comparing commonly used correlation techniques are considered. General expressions for determining the reconstruction error for specific image sampling strategies are developed.
Strong correlations between incoherent vortices.
Jesus-Silva, A J; Hickmann, J M; Fonseca, E J S
2012-08-27
We establish a correlation rule of which the value of the topological charge obtained in intensity correlation between two coherence vortices is such that this value is bounded by the topological charge of each coherence vortex. The original phase information is scrambled in each speckle pattern and unveiled using numerical intensity correlation. According to this rule, it is also possible to obtain a coherence vortex stable, an integer vortex, even when each incoherent vortex beam is instable, non-integer vortex. PMID:23037023
Correlated oxides: Metals amassing transparency
NASA Astrophysics Data System (ADS)
Poeppelmeier, Kenneth R.; Rondinelli, James M.
2016-02-01
Conducting complex oxides with correlated electrons at room temperature offer a less explored materials platform for the high conductivity and optical transparency needed for ultrathin invisible circuitry.
Photon correlations in multimode waveguides
Poem, Eilon; Silberberg, Yaron
2011-10-15
We consider the propagation of classical and nonclassical light in multimode optical waveguides. We focus on the evolution of the few-photon correlation functions, which, much as the light-intensity distribution in such systems, evolve in a periodic manner, culminating in the ''revival'' of the initial correlation pattern at the end of each period. It is found that when the input state possesses nontrivial symmetries, the correlation revival period can be longer than that of the intensity, and thus the same intensity pattern can display different correlation patterns. We experimentally demonstrate this effect for classical, pseudothermal light, and compare the results with the predictions for nonclassical, quantum light.
Cross-correlation laser scattering.
Kam, Z; Rigler, R
1982-01-01
Cross-correlation between two detectors was applied to analyze laser light-scattering fluctuations. Laser scattering from random concentration fluctuations is spatially coherent over small angular areas that are inversely proportional in size to the dimension of the scattering volume. By cross-correlating scattering intensity fluctuations in different angles, the correlation due to relaxation of concentration fluctuations is practically eliminated, and correlations reflecting changes in the scattering from the individual particles can be enhanced. Rotational diffusion of assymetric particles, conformational relaxation of random coils, and association-dissociation dynamics are determined here using the above approach. PMID:7049259
Why Are Experts Correlated? Decomposing Correlations between Judges
ERIC Educational Resources Information Center
Broomell, Stephen B.; Budescu, David V.
2009-01-01
We derive an analytic model of the inter-judge correlation as a function of five underlying parameters. Inter-cue correlation and the number of cues capture our assumptions about the environment, while differentiations between cues, the weights attached to the cues, and (un)reliability describe assumptions about the judges. We study the relative…
Wang, Lan; Wang, Chao; Deng, Daogui; Zhao, Xiuxia; Zhou, Zhongze
2015-09-01
Temporal and spatial variations in the phytoplankton community and environmental variables were investigated from February to July 2014, in the upper lake of Shengjin Lake, China. We identified 192 species of phytoplankton belonging to 8 phyla and 84 genera, of which 46.4% of Chlorophyta, 29.2% of Bacillariophyta, and 12.5% of Cyanophyta. There were 14 predominant species. Marked temporal and spatial variations were observed in the phytoplankton community. The total abundance of phytoplankton ranged from 3.66?×?10(5) to 867.93?×?10(5) cells/L and total biomass ranging from 0.40 to 20.89 mg/L. The Shannon-Wiener diversity index varied from 3.50 to 8.35 with an average of 5.58, revealing high biodiversity in the phytoplankton community. There were substantial temporal changes in the dominant species, from Bacillariophyta and Cryptophyta to Cyanophyta and Chlorophyta. Phytoplankton biomass and abundance showed a similar increasing trend from February to July. Pearson correlations and Redundancy analysis revealed that the most significant environmental factors influencing phytoplankton community were water temperature (T), transparency (SD), and nutrient concentration. The positive correlation between the key water bird areas and phytoplankton biomass indicated that the droppings of wintering water birds had an important influence on the phytoplankton community in the upper lake of Shengjin Lake. PMID:25966883
Is meat quality from Longissimus lumborum samples correlated with other cuts in horse meat?
De Palo, Pasquale; Maggiolino, Aristide; Centoducati, Pasquale; Milella, Paola; Calzaretti, Giovanna; Tateo, Alessandra
2016-03-01
The present work aims to investigate if the variation of each parameter in Longissimus lumborum muscle could correspond to the same or to a similar variation of the parameter in the other muscles. The work presents results of Pearson's correlations between Longissimus lumborum samples and other muscle samples, such as Biceps femoris, Rectus femoris, Semimembranosus, Supraspinatus and Semitendinosus in horse meat. A total of 27 male IHDH (Italian Heavy Draught Horse) breed foals were employed. They were slaughtered at 11 months of age and the above-mentioned muscles were sampled. The Longissimus lumborum muscle showed to be representative of other muscles and of the whole carcass for some chemical parameters (moisture, protein and ash) and for some fatty acids profile patterns such as C12:0, C14:0, total monounsaturated fatty acid and polyunsaturated fatty acid, but poor correlations were recorded for intramuscular fat concentration, rheological and colorimetric parameters. Although almost all the qualitative parameters in meat are affected by the anatomical site and by the muscle, the Longissimus lumborum is often not representative in horse meat with regard to modifications of this parameters. PMID:26464235
Beyond Weber's Law: A Second Look at Ranking Visualizations of Correlation.
Kay, Matthew; Heer, Jeffrey
2016-01-01
Models of human perception - including perceptual "laws" - can be valuable tools for deriving visualization design recommendations. However, it is important to assess the explanatory power of such models when using them to inform design. We present a secondary analysis of data previously used to rank the effectiveness of bivariate visualizations for assessing correlation (measured with Pearson's r) according to the well-known Weber-Fechner Law. Beginning with the model of Harrison et al. [1], we present a sequence of refinements including incorporation of individual differences, log transformation, censored regression, and adoption of Bayesian statistics. Our model incorporates all observations dropped from the original analysis, including data near ceilings caused by the data collection process and entire visualizations dropped due to large numbers of observations worse than chance. This model deviates from Weber's Law, but provides improved predictive accuracy and generalization. Using Bayesian credibility intervals, we derive a partial ranking that groups visualizations with similar performance, and we give precise estimates of the difference in performance between these groups. We find that compared to other visualizations, scatterplots are unique in combining low variance between individuals and high precision on both positively- and negatively-correlated data. We conclude with a discussion of the value of data sharing and replication, and share implications for modeling similar experimental data. PMID:26390485
Oliver, Lorraine
2012-01-01
Objective The mode of influence of the aromas of plant essential oils on human behaviour is largely unclear. This study was designed to assess the potential pharmacological relationships between absorbed 1,8-cineole following exposure to rosemary aroma, cognitive performance and mood. Methods Twenty healthy volunteers performed serial subtraction and visual information processing tasks in a cubicle diffused with the aroma of rosemary. Mood assessments were made pre and post testing, and venous blood was sampled at the end of the session. Pearson correlations were carried out between serum levels of 1,8-cineole, cognitive performance measures and change in mood scores. Results Here we show for the first time that performance on cognitive tasks is significantly related to concentration of absorbed 1,8-cineole following exposure to rosemary aroma, with improved performance at higher concentrations. Furthermore, these effects were found for speed and accuracy outcomes, indicating that the relationship is not describing a speedâ€“accuracy trade off. The relationships between 1,8-cineole levels and mood were less pronounced, but did reveal a significant negative correlation between change in contentment and plasma 1,8-cineole levels. Conclusion These findings suggest that compounds absorbed from rosemary aroma affect cognition and subjective state independently through different neurochemical pathways. PMID:23983963
A novel joint sparse partial correlation method for estimating group functional networks.
Liang, Xiaoyun; Connelly, Alan; Calamante, Fernando
2016-03-01
Advances in graph theory have provided a powerful tool to characterize brain networks. In particular, functional networks at group-level have great appeal to gain further insight into complex brain function, and to assess changes across disease conditions. These group networks, however, often have two main limitations. First, they are popularly estimated by directly averaging individual networks that are compromised by confounding variations. Secondly, functional networks have been estimated mainly through Pearson cross-correlation, without taking into account the influence of other regions. In this study, we propose a sparse group partial correlation method for robust estimation of functional networks based on a joint graphical models approach. To circumvent the issue of choosing the optimal regularization parameters, a stability selection method is employed to extract networks. The proposed method is, therefore, denoted as JGMSS. By applying JGMSS across simulated datasets, the resulting networks show consistently higher accuracy and sensitivity than those estimated using an alternative approach (the elastic-net regularization with stability selection, ENSS). The robustness of the JGMSS is evidenced by the independence of the estimated networks to choices of the initial set of regularization parameters. The performance of JGMSS in estimating group networks is further demonstrated with in vivo fMRI data (ASL and BOLD), which show that JGMSS can more robustly estimate brain hub regions at group-level and can better control intersubject variability than it is achieved using ENSS. Hum Brain Mapp 37:1162-1177, 2016. Â© 2015 Wiley Periodicals, Inc. PMID:26859311
Kim, Gwang-Won; Jeong, Gwang-Woo
2015-12-16
The aim of this study was to evaluate the white matter (WM) volume change and its correlation with symptom severity in patients with schizophrenia using voxel-based morphometry. A total of 20 patients with schizophrenia and 20 age-matched healthy controls participated in this study. MR image data were processed using SPM8 software with diffeomorphic anatomical registration through an exponentiated Lie algebra (DARTEL) algorithm. The patients with schizophrenia showed significant decreases (P=0.042) in the WM volumes of the temporal lobe and superior frontal gyrus compared with the healthy controls. The WM volumes of the middle temporal gyrus were negatively correlated with the scores of both the Positive Subscale (Pearson's Ď=-0.68, P=0.001) and the Negative Subscale (Ď=-0.71, P=0.0005) in the Positive and Negative Syndrome Scale. In addition, the scores of the General Psychopathology Subscale were negatively correlated with the WM volumes of the superior frontal gyrus (Ď=-0.68, P=0.0009). This study evaluated the WM volume of patients with schizophrenia compared with healthy controls using DARTEI-based voxel-based morphometry and also assessed the correlation of the localized WM volume changes with the Positive and Negative Syndrome Scale. These findings will be useful to understand the neuropathology associated with WM abnormality in schizophrenia. PMID:26485094
Vega, W H O; Quirino, C R; SerapiĂŁo, R V; Oliveira, C S; Pacheco, A
2015-01-01
The growth of the Gyr breed in Brazil in terms of genetic gain for milk, along with conditions for market, has led to the use of ovum pick-up in vitro production (OPU-IVP) as a leader in biotechnology for the multiplication of genetic material. The aim of this study was to investigate phenotypic correlations between OPU-IVP-linked characteristics and pregnancy rates registered in an embryo transfer program using Gyr cows as oocyte donors. Data collected from 211 OPU sessions and 298 embryo transfers during the years 2012 and 2013 were analyzed and statistical analysis was performed. Estimates of simple Pearson correlations were calculated for NVcoc and PVcoc (number and proportion of viable cumulus-oocyte complexes, respectively); NcleavD4 and PcleavD4 (number and proportion of cleaved embryos on day 4 of culture, respectively); NTembD7 and PTembD7 (number and proportion of transferable embryos on day 7 of culture, respectively); NPrD30 and PPrD30 (number and proportion of pregnancies 30 days after transfer, respectively); and NPrD60 and PPrD60 (number and proportion of pregnancies 60 days after transfer, respectively). Moderate to moderately high correlations were found for all numerical characteristics, suggesting these as the most suitable parameters for selection of oocyte donors in Gyr programs. NVcoc is proposed as a selection trait due to positive correlations with percentage traits and pregnancy rates 30 and 60 days after transfer. PMID:26214412
2014-01-01
Background Atherosclerotic plaque progression and rupture are believed to be associated with mechanical stress conditions. In this paper, patient-specific in vivo intravascular ultrasound (IVUS) coronary plaque image data were used to construct computational models with fluid-structure interaction (FSI) and cyclic bending to investigate correlations between plaque wall thickness and both flow shear stress and plaque wall stress conditions. Methods IVUS data were acquired from 10 patients after voluntary informed consent. The X-ray angiogram was obtained prior to the pullback of the IVUS catheter to determine the location of the coronary artery stenosis, vessel curvature and cardiac motion. Cyclic bending was specified in the model representing the effect by heart contraction. 3D anisotropic FSI models were constructed and solved to obtain flow shear stress (FSS) and plaque wall stress (PWS) values. FSS and PWS values were obtained for statistical analysis. Correlations with pâ€‰<â€‰0.05 were deemed significant. Results Nine out of the 10 patients showed positive correlation between wall thickness and flow shear stress. The mean Pearson correlation r-value was 0.278â€‰Â±â€‰0.181. Similarly, 9 out of the 10 patients showed negative correlation between wall thickness and plaque wall stress. The mean Pearson correlation r-value was -0.530â€‰Â±â€‰0.210. Conclusion Our results showed that plaque vessel wall thickness correlated positively with FSS and negatively with PWS. The patient-specific IVUS-based modeling approach has the potential to be used to investigate and identify possible mechanisms governing plaque progression and rupture and assist in diagnosis and intervention procedures. This represents a new direction of research. Further investigations using more patient follow-up data are warranted. PMID:24669780
Regularized Generalized Canonical Correlation Analysis
ERIC Educational Resources Information Center
Tenenhaus, Arthur; Tenenhaus, Michel
2011-01-01
Regularized generalized canonical correlation analysis (RGCCA) is a generalization of regularized canonical correlation analysis to three or more sets of variables. It constitutes a general framework for many multi-block data analysis methods. It combines the power of multi-block data analysis methods (maximization of well identified criteria) and…
Correlation Weights in Multiple Regression
ERIC Educational Resources Information Center
Waller, Niels G.; Jones, Jeff A.
2010-01-01
A general theory on the use of correlation weights in linear prediction has yet to be proposed. In this paper we take initial steps in developing such a theory by describing the conditions under which correlation weights perform well in population regression models. Using OLS weights as a comparison, we define cases in which the two weighting…
Personality Correlates of Polydrug Abuse.
ERIC Educational Resources Information Center
Kilpatrick, Dean G.; And Others
Although the personality correlates of heroin addiction, LSD use, and marijuana smoking have been frequently investigated, relatively few data are available to describe the personality or lifestyle variables correlated with the pattern of polydrug abuse. In an attempt to gather such information, 17 polydrug users, selected from a group of 224…
Generalized Constrained Canonical Correlation Analysis.
ERIC Educational Resources Information Center
Takane, Yoshio; Hwang, Heungsun
2002-01-01
Proposes a method for generalized constrained canonical correlation analysis (GCCANO) that incorporates external information on both rows and columns of data matrices. In this method, each set of variables is first decomposed into the sum of several submatrices according to the external information, and then canonical correlation analysis isâ€¦
Psychophysical correlations, synchronicity and meaning.
Atmanspacher, Harald
2014-04-01
The dual-aspect framework which Jung developed with Wolfgang Pauli implies that psychophysical phenomena are neither reducible to physical processes nor to conscious mental activity. Rather, they constitute a radically novel kind of phenomena, deriving from correlations between the physical and the mental. In synchronistic events, a particular subclass of psychophysical phenomena, these correlations are explicated as experienced meaning. PMID:24673273
Regularized Generalized Canonical Correlation Analysis
ERIC Educational Resources Information Center
Tenenhaus, Arthur; Tenenhaus, Michel
2011-01-01
Regularized generalized canonical correlation analysis (RGCCA) is a generalization of regularized canonical correlation analysis to three or more sets of variables. It constitutes a general framework for many multi-block data analysis methods. It combines the power of multi-block data analysis methods (maximization of well identified criteria) andâ€¦
Correlation between National Influenza Surveillance Data and Google Trends in South Korea
Jo, Min Woo; Shin, Soo-Yong; Lee, Jae Ho; Ryoo, Seoung Mok; Kim, Won Young; Seo, Dong-Woo
2013-01-01
Background In South Korea, there is currently no syndromic surveillance system using internet search data, including Google Flu Trends. The purpose of this study was to investigate the correlation between national influenza surveillance data and Google Trends in South Korea. Methods Our study was based on a publicly available search engine database, Google Trends, using 12 influenza-related queries, from September 9, 2007 to September 8, 2012. National surveillance data were obtained from the Korea Centers for Disease Control and Prevention (KCDC) influenza-like illness (ILI) and virologic surveillance system. Pearson's correlation coefficients were calculated to compare the national surveillance and the Google Trends data for the overall period and for 5 influenza seasons. Results The correlation coefficient between the KCDC ILI and virologic surveillance data was 0.72 (p<0.05). The highest correlation was between the Google Trends query of H1N1 and the ILI data, with a correlation coefficient of 0.53 (p<0.05), for the overall study period. When compared with the KCDC virologic data, the Google Trends query of bird flu had the highest correlation with a correlation coefficient of 0.93 (p<0.05) in the 2010-11 season. The following queries showed a statistically significant correlation coefficient compared with ILI data for three consecutive seasons: Tamiflu (r?=?0.59, 0.86, 0.90, p<0.05), new flu (r?=?0.64, 0.43, 0.70, p<0.05) and flu (r?=?0.68, 0.43, 0.77, p<0.05). Conclusions In our study, we found that the Google Trends for certain queries using the survey on influenza correlated with national surveillance data in South Korea. The results of this study showed that Google Trends in the Korean language can be used as complementary data for influenza surveillance but was insufficient for the use of predictive models, such as Google Flu Trends. PMID:24339927
Balog, Judit; Thijssen, Peter E; de Greef, Jessica C; Shah, Bharati; van Engelen, Baziel G M; Yokomori, Kyoko; Tapscott, Stephen J; Tawil, Rabi; van der Maarel, Silvčre M
2012-06-01
The aim of our study was to identify relationships between epigenetic parameters correlating with a relaxed chromatin state of the DUX4 promoter region and clinical severity as measured by a clinical severity score or muscle pathologic changes in D4Z4 contraction-dependent (FSHD1) and -independent (FSHD2) facioscapulohumeral muscular dystrophy patients. Twenty primary fibroblast (5 control, 10 FSHD1 and 5 FSHD2) and 26 primary myoblast (9 control, 12 FSHD1 and 5 FSHD2) cultures originating from patients with FSHD and controls were analyzed. Histone modification levels were determined by chromatin immunoprecipitation. We examined correlations between the chromatin compaction score (ChCS) defined by the H3K9me3:H3K4me2 ratio and an age corrected clinical severity score (CSS) or muscle pathology score (MPS). Possible relationships were investigated using linear regression analysis and significance was tested by Pearson's product-moment coefficient. We found a significant difference of the ChCS between controls and patients with FSHD1 and between controls and patients with FSHD2. Tissue specific differences in ChCS were also observed. We also found a near-significant relationship between ChCS and the age corrected CSS in fibroblasts but not in myoblasts. Surprisingly, we found a strong correlation between the MPS of the vastus lateralis and the CSS. Our results confirm the D4Z4 chromatin relaxation previously shown to be associated with FSHD in a small number of samples. A possible relationship between clinical and epigenetic parameters could be established in patient fibroblasts, but not in myoblasts. The strong correlation between the MPS of the vastus lateralis and the CSS suggests that this muscle can be used to study for surrogate markers of overall disease severity. PMID:22522912
Lopes, Stella Crosara; Pagnano, ValĂ©ria Oliveira; Rollo, JoĂŁo Manuel Domingos de Almeida; Leal, MĂ´nica Barbosa; Bezzon, Osvaldo Luiz
2009-01-01
The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10-6 Â°C-1) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs. PMID:19274398
Poynton, Helen C; Robinson, William E; Blalock, Bonnie J; Hannigan, Robyn E
2014-10-01
Marine biomonitoring programs in the U.S. and Europe have historically relied on monitoring tissue concentrations of bivalves to monitor contaminant levels and ecosystem health. By integrating 'omic methods with these tissue residue approaches we can uncover mechanistic insight to link tissue concentrations to potential toxic effects. In an effort to identify novel biomarkers and better understand the molecular toxicology of metal bioaccumulation in bivalves, we exposed the blue mussel, Mytilus edulis L., to sub-lethal concentrations (0.54 ÎĽM) of cadmium, lead, and a Cd+Pb mixture. Metal concentrations were measured in gill tissues at 1, 2, and 4 weeks, and increased linearly over the 4 week duration. In addition, there was evidence that Pb interfered with Cd uptake in the mixture treatment. Using a 3025 sequence microarray for M. edulis, we performed transcriptomic analysis, identifying 57 differentially expressed sequences. Hierarchical clustering of these sequences successfully distinguished the different treatment groups demonstrating that the expression profiles were reproducible among the treatments. Enrichment analysis of gene ontology terms identified several biological processes that were perturbed by the treatments, including nucleoside phosphate biosynthetic processes, mRNA metabolic processes, and response to stress. To identify transcripts whose expression level correlated with metal bioaccumulation, we performed Pearson correlation analysis. Several transcripts correlated with gill metal concentrations including mt10, mt20, and contig 48, an unknown transcript containing a wsc domain. In addition, three transcripts directly involved in the unfolded protein response (UPR) were induced in the metal treatments at 2 weeks and were further up-regulated at 4 weeks. Overall, correlation of tissue concentrations and gene expression responses indicates that as mussels accumulate higher concentrations of metals, initial stress responses are mobilized to protect tissues. However, given the role of UPR in apoptosis, it serves as an early indicator of stress, which once overwhelmed will result in adverse physiological effects. PMID:25016106
Saenz-Frances, Federico; JaĂ±ez, Luis; Borrego-Sanz, Lara; Berrozpe-Villabona, Clara; Martinez-de-la-Casa, Jose Maria; Morales-Fernandez, Laura; Garcia-Sanchez, Julian; Santos-Bueso, Enrique; Garcia-Feijoo, Julian
2015-01-01
AIM To correlate corneal variables (determined using the Pentacam) with optic nerve head (ONH) variables determined using the Heidelberg retina tomograph (HRT) in healthy subjects and patients diagnosed with primary open angle glaucoma (POAG). METHODS Measurements were made in 75 healthy eyes and 73 eyes with POAG and correlations examined through Pearson correlation coefficients between the two sets of variables in the two subject groups. The corneal variables determined were corneal volume (CVol), central corneal thickness (CCT), overall corneal thickness (OvCT), the mean thickness of a circular zone centered at the corneal apex of 1 mm radius (zone I) and the mean thickness of several concentric rings, also centered at the apex until the limbus, each of 1 mm width (zones II to VI respectively). The ONH variables were determined using the HRT. RESULTS The following pairs of variables were correlated in the control group: CCT-disc area (DAr) (-0.48; P<0.0001), Zone I-DAr (-0.503; P<0.0001) and Zone II-DAr (-0.443; P<0.0001); and in the POAG group: CCT-cup-to-disc area ratio (CDRa) (-0.402; P<0.0001), Zone I-CDRa (-0.418; P<0.0001), Zone II-CDRa (-0.405; P=0.006), Zone I-cup shape measure (CSM) (-0.415; P=0.002), Zone II-CSM (-0.405; P=0.001), Zone IV-height variation contour (HVC) (0.378; P=0.002); Zone V-HVC (0.388, P<0.0001). CONCLUSIONS In the healthy subjects, significant negative correlation was detected between central and paracentral corneal thickness and optic disc area. In contrast, the POAG patients showed significant negative correlation between central and paracentral corneal thickness and the cup-disc ratio and CSM, and positive correlation between peripheral corneal thickness and HVC. PMID:26682165
COSTA, Yuri Martins; PORPORATTI, André Luís; HILGENBERG-SYDNEY, Priscila Brenner; BONJARDIM, Leonardo Rigoldi; CONTI, Paulo César Rodrigues
2015-01-01
ABSTRACT Low pressure Pain Threshold (PPT) is considered a risk factor for Temporomandibular Disorders (TMD) and is influenced by psychological variables. Objectives To correlate deep pain sensitivity of masticatory muscles with prosthetic factors and Oral-Health-Related Quality of Life (OHRQoL) in completely edentulous subjects. Material and Methods A total of 29 complete denture wearers were recruited. The variables were: a) Pressure Pain Threshold (PPT) of the masseter and temporalis; b) retention, stability, and tooth wear of dentures; c) Vertical Dimension of Occlusion (VDO); d) Oral Health Impact Profile (OHIP) adapted to orofacial pain. The Kolmogorov-Smirnov test, the Pearson Product-Moment correlation coefficient, the Spearman Rank correlation coefficient, the Point-Biserial correlation coefficient, and the Bonferroni correction (?=1%) were applied to the data. Results The mean age (standard deviation) of the participants was of 70.1 years (9.5) and 82% of them were females. There were no significant correlations with prosthetic factors, but significant negative correlations were found between the OHIP and the PPT of the anterior temporalis (r=-0.50, 95% CI-0.73 to 0.17, p=0.005). Discussion The deep pain sensitivity of masticatory muscles in complete dentures wearers is associated with OHRQoL, but not with prosthetic factors.
Hasan, Shadi W; Elektorowicz, Maria; Oleszkiewicz, Jan A
2012-09-01
The influence of sludge properties in SMEBR and conventional MBR pilot systems on membrane fouling was investigated. Generated data were analyzed using statistical analysis Pearson's product momentum correlation coefficient (r(p)). Analysis showed that TMP had strong direct (r(p)=0.9182) and inverse (r(p)=-0.9205) correlations to mean particle size diameter in MBR and SMEBR, respectively. TMP in SMEBR had a strong direct correlation to the sludge mixed liquor suspended solids concentration (MLSS) (r(p)=0.7757) while a weak direct correlation (r(p)=0.1940) was observed in MBR. SMEBR showed a moderate inverse correlation (r(p)=-0.6118) between TMP and soluble carbohydrates (EPS(c)) and a very weak direct correlation (r(p)=0.3448) to soluble proteins (EPS(p)). Conversely, EPS(p) in MBR had more significant impact (r(p)=0.4856) on membrane fouling than EPS(c) (r(p)=0.3051). The results provide insight into optimization of operational conditions in SMEBR system to overcome membrane fouling. PMID:22797086
Resch, Hemma; Pereira, Ivania; Weber, Stephanie; Holzer, Stephan; Fischer, Georg
2015-01-01
Purpose: Aim of the present study was to evaluate whether there is a correlation between retinal blood vessel density (RVD) and the peripapillary retinal nerve fiber layer (RNFL) thickness profile. Methods: RNFL thickness of 106 healthy subjects was measured using scanning laser polarimetry, GDx variable corneal compensation (VCC), and GDx enhanced corneal compensation (ECC). A proprietary software was developed in MATLAB to measure the peripapillary retinal vessels using scanning laser ophthalmoscopy fundus images, centered on the optic disc measured by Cirrus spectral domain optical coherence tomography. The individual retinal vessel positions and thickness values were integrated in a 64-sector RVD profile and intrasubject and intersubject correlations were calculated. Results: The mean R value±SD for intrasubject correlation between RVD and RNFL thickness measured with GDx VCC and GDx ECC was 0.714±0.157 and 0.629±0.140, with 105 of 106 subjects presenting significant correlations. In the intersubject linear regression analysis for GDx VCC, 33 of 64 (52%) sectors presented a significant Pearson correlation coefficient between RNFL thickness and RVD values, with a mean R value of 0.187±0.135 (P<0.05). Conclusions: Peripapillary RNFL thickness profiles correlate with the RVD over 50% of the sectors and might explain up to 26% of the interindividual variance of the peripapillary RNFL thickness values as measured with GDx VCC. To our opinion, taking into account RVD might reduce interindividual variation in peripapillary RNFL thickness profiles measured with scanning laser polarimetry. PMID:25719231
Prevalence and Correlates of School Bullying Victimization in Xi'an, China.
Zhu, Yuhong; Chan, Ko Ling
2015-01-01
This study used the data from a representative sample to estimate the prevalence of child bullying victimization in Xi'an, China. Data on social demographic information and the experiences of different types of bullying victimization were collected from a randomly selected sample with 3,175 middle school students aged 15-17 years by self-administrated questionnaires. t Test, ?2 test, and multiple logistic regression analyses were used to test group differences and examine the correlates of bullying victimization. Results show that 54.9% and 44.6% of Chinese children have been bullied in a lifetime and in the preceding year, respectively. Correlates for direct and relational bullying victimization includes male participants, father's lower education level, father's unemployment, having one or more siblings, smoking, depression, borderline personality trait, posttraumatic stress disorder, and from rural schools. Overall, the prevalence of child bullying victimization in China is substantial. The multiple correlates suggest prevention and intervention of bullying victimization in a holistic and comprehensive way. PMID:26159148
Serefoglu, Ege Can; Karacay, Safak; Ozdemir, Ahmet Tunc; Kalkan, Mehmet; Yencilek, Faruk
2014-01-01
Introduction Premature ejaculation (PE) is the most common male sexual dysfunction. Monosymptomatic enuresis (ME) is nocturnal bed wetting, without any daytime symptoms. Recent clinical studies report an association between lifelong PE and ME. The purpose of this study was to compare the intravaginal ejaculatory time (IELT) between lifelong PE in men with and without ME. The goal was to determine if there is an association between the severity of ME and of IELT. Material and methods A total of 137 men with lifelong PE were included in this study. Subjects were asked if they had childhood ME. The characteristics and mean IELTs of patients with and without ME were compared using the student's t–test, and the correlation between severity of ME and IELT was assessed with trend test. Results Of the 137 lifelong PE patients, 57 reported ME. There was a strong negative correlation in patients with ME between the severity of enuresis and IELT, with IELT being shorter in patients with severe ME. Conclusions A strong correlation between IELT and the severity of ME suggests a common underlying mechanism. Further studies are required to confirm these findings and elucidate the exact pathophysiology. PMID:24982787
Correlation of neurocognitive function and brain parenchyma volumes in children surviving cancer
NASA Astrophysics Data System (ADS)
Reddick, Wilburn E.; White, Holly A.; Glass, John O.; Mulhern, Raymond K.
2002-04-01
This research builds on our hypothesis that white matter damage and associated neurocognitive symptoms, in children treated for cancer with cranial spinal irradiation, spans a continuum of severity that can be reliably probed using non-invasive MR technology. Quantitative volumetric assessments of MR imaging and psychological assessments were obtained in 40 long-term survivors of malignant brain tumors treated with cranial irradiation. Neurocognitive assessments included a test of intellect (Wechsler Intelligence Test for Children, Wechsler Adult Intelligence Scale), attention (Conner's Continuous Performance Test), and memory (California Verbal Learning Test). One-sample t-tests were conducted to evaluate test performance of survivors against age-adjusted scores from the test norms; these analyses revealed significant impairments in all apriori selected measures of intelligence, attention, and memory. Partial correlation analyses were performed to assess the relationships between brain tissues volumes (normal appearing white matter (NAWM), gray matter, and CSF) and neurocognitive function. Global intelligence (r = 0.32, p = 0.05) and global attentional (r = 0.49, p < 0.01) were significantly positively correlated with NAWM volumes, whereas global memory was significantly positively correlated with overall brain parenchyma (r = 0.38, p = 0.04). We conclude that quantitative assessment of MR examinations in survivors of childhood cancer treated with cranial irradiation reveal that loss of NAWM is associated with decreased intellectual and attentional deficits, whereas overall parenchyma loss, as reflected by increased CSF and decreased white matter, is associated with memory-related deficits.
Kimbell, J S; Frank, D O; Laud, Purushottam; Garcia, G J M; Rhee, J S
2013-10-18
Surgeries to correct nasal airway obstruction (NAO) often have less than desirable outcomes, partly due to the absence of an objective tool to select the most appropriate surgical approach for each patient. Computational fluid dynamics (CFD) models can be used to investigate nasal airflow, but variables need to be identified that can detect surgical changes and correlate with patient symptoms. CFD models were constructed from pre- and post-surgery computed tomography scans for 10 NAO patients showing no evidence of nasal cycling. Steady-state inspiratory airflow, nasal resistance, wall shear stress, and heat flux were computed for the main nasal cavity from nostrils to posterior nasal septum both bilaterally and unilaterally. Paired t-tests indicated that all CFD variables were significantly changed by surgery when calculated on the most obstructed side, and that airflow, nasal resistance, and heat flux were significantly changed bilaterally as well. Moderate linear correlations with patient-reported symptoms were found for airflow, heat flux, unilateral allocation of airflow, and unilateral nasal resistance as a fraction of bilateral nasal resistance when calculated on the most obstructed nasal side, suggesting that these variables may be useful for evaluating the efficacy of nasal surgery objectively. Similarity in the strengths of these correlations suggests that patient-reported symptoms may represent a constellation of effects and that these variables should be tracked concurrently during future virtual surgery planning. PMID:24063885
Kimbell, J.S.; Frank, D.O.; Laud, Purushottam; Garcia, G.J.M.; Rhee, J.S.
2014-01-01
Surgeries to correct nasal airway obstruction (NAO) often have less than desirable outcomes, partly due to the absence of an objective tool to select the most appropriate surgical approach for each patient. Computational fluid dynamics (CFD) models can be used to investigate nasal airflow, but variables need to be identified that can detect surgical changes and correlate with patient symptoms. CFD models were constructed from pre- and post-surgery computed tomography scans for 10 NAO patients showing no evidence of nasal cycling. Steady-state inspiratory airflow, nasal resistance, wall shear stress, and heat flux were computed for the main nasal cavity from nostrils to posterior nasal septum both bilaterally and unilaterally. Paired t-tests indicated that all CFD variables were significantly changed by surgery when calculated on the most obstructed side, and that airflow, nasal resistance, and heat flux were significantly changed bilaterally as well. Moderate linear correlations with patient-reported symptoms were found for airflow, heat flux, unilateral allocation of airflow, and unilateral nasal resistance as a fraction of bilateral nasal resistance when calculated on the most obstructed nasal side, suggesting that these variables may be useful for evaluating the efficacy of nasal surgery objectively. Similarity in the strengths of these correlations suggests that patient-reported symptoms may represent a constellation of effects and that these variables should be tracked concurrently during future virtual surgery planning. PMID:24063885
25 ns software correlator for photon and fluorescence correlation spectroscopy
NASA Astrophysics Data System (ADS)
Magatti, Davide; Ferri, Fabio
2003-02-01
A 25 ns time resolution, multi-tau software correlator developed in LABVIEW based on the use of a standard photon counting unit, a fast timer/counter board (6602-PCI National Instrument) and a personal computer (PC) (1.5 GHz Pentium 4) is presented and quantitatively discussed. The correlator works by processing the stream of incoming data in parallel according to two different algorithms: For large lag times (Ď„â©ľ100 ÎĽs), a classical time-mode (TM) scheme, based on the measure of the number of pulses per time interval, is used; differently, for Ď„â©˝100 ÎĽs a photon-mode (PM) scheme is adopted and the time sequence of the arrival times of the photon pulses is measured. By combining the two methods, we developed a system capable of working out correlation functions on line, in full real time for the TM correlator and partially in batch processing for the PM correlator. For the latter one, the duty cycle depends on the count rate of the incoming pulses, being Ëś100% for count rates â©˝3Ă—104 Hz, Ëś15% at 105 Hz, and Ëś1% at 106 Hz. For limitations imposed by the fairly small first-in, first-out (FIFO) buffer available on the counter board, the maximum count rate permissible for a proper functioning of the PM correlator is limited to Ëś105 Hz. However, this limit can be removed by using a board with a deeper FIFO. Similarly, the 25 ns time resolution is only limited by maximum clock frequency available on the 6602-PCI and can be easily improved by using a faster clock. When tested on dilute solutions of calibrated latex spheres, the overall performances of the correlator appear to be comparable with those of commercial hardware correlators, but with several nontrivial advantages related to its flexibility, low cost, and easy adaptability to future developments of PC and data acquisition technology.
Cluster identification based on correlations.
Schulman, L S
2012-04-01
The problem addressed is the identification of cooperating agents based on correlations created as a result of the joint action of these and other agents. A systematic method for using correlations beyond second moments is developed. The technique is applied to a didactic example, the identification of alphabet letters based on correlations among the pixels used in an image of the letter. As in this example, agents can belong to more than one cluster. Moreover, the identification scheme does not require that the patterns be known ahead of time. PMID:22680426
Cluster identification based on correlations
NASA Astrophysics Data System (ADS)
Schulman, L. S.
2012-04-01
The problem addressed is the identification of cooperating agents based on correlations created as a result of the joint action of these and other agents. A systematic method for using correlations beyond second moments is developed. The technique is applied to a didactic example, the identification of alphabet letters based on correlations among the pixels used in an image of the letter. As in this example, agents can belong to more than one cluster. Moreover, the identification scheme does not require that the patterns be known ahead of time.
Correlation, Cost Risk, and Geometry
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1992-01-01
The geometric viewpoint identifies the choice of a correlation matrix for the simulation of cost risk with the pairwise choice of data vectors corresponding to the parameters used to obtain cost risk. The correlation coefficient is the cosine of the angle between the data vectors after translation to an origin at the mean and normalization for magnitude. Thus correlation is equivalent to expressing the data in terms of a non orthogonal basis. To understand the many resulting phenomena requires the use of the tensor concept of raising the index to transform the measured and observed covariant components into contravariant components before vector addition can be applied. The geometric viewpoint also demonstrates that correlation and covariance are geometric properties, as opposed to purely statistical properties, of the variates. Thus, variates from different distributions may be correlated, as desired, after selection from independent distributions. By determining the principal components of the correlation matrix, variates with the desired mean, magnitude, and correlation can be generated through linear transforms which include the eigenvalues and the eigenvectors of the correlation matrix. The conversion of the data to a non orthogonal basis uses a compound linear transformation which distorts or stretches the data space. Hence, the correlated data does not have the same properties as the uncorrelated data used to generate it. This phenomena is responsible for seemingly strange observations such as the fact that the marginal distributions of the correlated data can be quite different from the distributions used to generate the data. The joint effect of statistical distributions and correlation remains a fertile area for further research. In terms of application to cost estimating, the geometric approach demonstrates that the estimator must have data and must understand that data in order to properly choose the correlation matrix appropriate for a given estimate. There is a general feeling by employers and managers that the field of cost requires little technical or mathematical background. Contrary to that opinion, this paper demonstrates that a background in mathematics equivalent to that needed for typical engineering and scientific disciplines at the masters or doctorate level is appropriate within the field of cost risk.
Mirrione,M.M.; Mirrione, M.M.; Schulz, D.; Dewey, S.L.; Henn, F.A.
2009-12-06
The learned helplessness paradigm has been repeatedly shown to correlate with neurobiological aspects of depression in humans. In this model, rodents are exposed inescapable foot-shock in order to reveal susceptibility to escape deficit, defined as 'learned helplessness' (LH). Few methods are available to probe the neurobiological aspects underlying the differences in susceptibility in the living animal, thus far being limited to studies examining regional neurochemical changes with microdialysis. With the widespread implementation of small animal neuroimaging methods, including positron emission tomography (PET), it is now possible to explore the living brain on a systems level to define regional changes that may correlate with vulnerability to stress. In this study, 12 wild type Sprague-Dawley rats were exposed to 40 minutes of inescapable foot-shock followed by metabolic imaging using 2-deoxy-2[{sup 18}F]fluoro-D-glucose (18-FDG) 1 hour later. The escape test was performed on these rats 48 hours later (to accommodate radiotracer decay), where they were given the opportunity to press a lever to shut off the shock. A region of interest (ROI) analysis was used to investigate potential correlations (Pearson Regression Coefficients) between regional 18-FDG uptake following inescapable shock and subsequent learned helpless behavior (time to finish the test; number of successful lever presses within 20 seconds of shock onset). ROI analysis revealed a significant positive correlation between time to finish and 18-FDG uptake, and a negative correlation between lever presses and uptake, in the medial thalamic area (p=0.033, p=0.036). This ROI included the paraventricular thalamus, mediodorsal thalamus, and the habenula. In an effort to account for possible spillover artifact, the posterior thalamic area (including ventral medial and lateral portions) was also evaluated but did not reveal significant correlations (p=0.870, p=0.897). No other significant correlations were found in additional regions analyzed including the nucleus accumbens, caudate putamen, substantia nigra, and amygdala. These data suggest that medial thalamic 18-FDG uptake during inescapable shock may contribute to subsequent escape deficits, and are not confounded by shock effects per se, since all animals received the same treatment prior to scanning. We have previously explored 18-FDG differences following the escape test session which also showed hyperactivity in the medial thalamus of learned helpless animals compared to non-learned helpless, and included additional cortical-limbic changes. Given the neuroanatomical connections between the medial thalamus (and habenula) with the prefrontal cortex and monoaminergic brain stem, one possible speculation is that abnormal neuronal activity in these areas during stress may set in motion circuitry changes that correlate with learned helpless behavior.
Costa, Alberto; Peppe, Antonella; Carlesimo, Giovanni Augusto; Zabberoni, Silvia; Scalici, Francesco; Caltagirone, Carlo; Angelucci, Francesco
2015-01-01
Brain-derived neurotrophic factor (BDNF) is a trophic factor regulating cell survival and synaptic plasticity. Recent findings indicate that BDNF could be a potential regulatory factor for cognitive functioning in normal and/or neuropathological conditions. With regard to neurological disorders, recent data suggest that individuals with Parkinson’s disease (PD) may be affected by cognitive deficits and that they have altered BDNF production. Therefore, the hypothesis can be advanced that BDNF levels are associated with the cognitive state of these patients. With this in mind, the present study was aimed at exploring the relationship between BDNF serum levels and cognitive functioning in PD patients with mild cognitive impairment (MCI). Thirteen PD patients with MCI were included in the study. They were administered an extensive neuropsychological test battery that investigated executive, episodic memory, attention, visual-spatial and language domains. A single score was obtained for each cognitive domain by averaging z-scores on tests belonging to that specific domain. BDNF serum levels were measured by enzyme-linked immunoassay (ELISA). Pearson’s correlation analyses were performed between BDNF serum levels and cognitive performance. Results showed a significant positive correlation between BDNF serum levels and both attention (p < 0.05) and executive (p < 0.05) domains. Moreover, in the executive domain we found a significant correlation between BDNF levels and scores on tests assessing working memory and self-monitoring/inhibition. These preliminary data suggest that BDNF serum levels are associated with cognitive state in PD patients with MCI. Given the role of BDNF in regulating synaptic plasticity, the present findings give further support to the hypothesis that this trophic factor may be a potential biomarker for evaluating cognitive changes in PD and other neurological syndromes associated with cognitive decline. PMID:26441580
A Correlation of Community College Math Readiness and Student Success
NASA Astrophysics Data System (ADS)
Brown, Jayna Nicole
Although traditional college students are more prepared for college-level math based on college admissions tests, little data have been collected on nontraditional adult learners. The purpose of this study was to investigate relationships between math placement tests and community college students' success in math courses and persistence to degree or certificate completion. Guided by Tinto's theory of departure and student retention, the research questions addressed relationships and predictability of math Computer-adaptive Placement Assessment and Support System (COMPASS) test scores and students' performance in math courses, persistence in college, and degree completion. After conducting correlation and regression analyses, no significant relationships were identified between COMPASS Math test scores and students' performance (n = 234) in math courses, persistence in college, or degree completion. However, independent t test and chi-squared analyses of the achievements of college students who tested into Basic Math (n = 138) vs. Introduction to Algebra (n = 96) yielded statistically significant differences in persistence (p = .039), degree completion (p < .001), performance (p = .008), and progress ( p = .001), indicating students who tested into Introduction to Algebra were more successful and persisted more often to degree completion. In order to improve instructional methods for Basic Math courses, a 3-day professional development workshop was developed for math faculty focusing on current, best practices in remedial math instruction. Implications for social change include providing math faculty with the knowledge and skills to develop new instructional methods for remedial math courses. A change in instructional methods may improve community college students' math competencies and degree achievement.
Establishing correlation of footprints with body weight--forensic aspects.
Krishan, Kewal
2008-07-18
Analysis of footprints can reveal very important clues which can be used as forensic evidence in crime scene investigation. Apart from giving idea about the bare foot morphology and individualistic characteristics, the footprints are also indicative of the body size of the person. The present study is an attempt to establish the correlation between footprints and body weight of individuals. The sample for the present study consists of 50 male subjects ranging in age from 18 to 30 years. The subjects belonging to Gujjar caste were randomly taken from a village near Chandigarh city in North India. Three kinds of bilateral footprints were taken from each subject. First, the footprints with the subject's normal weight were taken, the footprints were taken when the subject holds 5 kg weight in his hands, then the footprints were taken when the subject holds 20 kg weight in his hands. In this way, the present study analyses 300 bilateral footprints obtained from 50 individuals. Nine measurements were taken on each footprint using precise and defined landmarks. The measurements of these three kinds of footprints were compared with each other and t-test was employed to see the significant variation. Some of the measurements of the footprints were altered significantly when the subject was subjected to 20 kg weight. However, there is no significant change when the subject holds 5 kg weight in his hands. Body weight was also estimated using regression method from the measurements of these three kinds of footprints. The utility of the study in offences like sexual assault, homicide, theft, burglary, mugging, stealing, shoplifting, dacoity, etc. has been discussed. PMID:18515026
Electronic correlations in the ironpnictides
Qazilbash, M. M.; Hamlin, J. J.; Baumbach, R. E.; Zhang, Lijun; Singh, David J; Maple, M. B.; Basov, D. N.
2009-01-01
In correlated metals derived from Mott insulators, the motion of an electron is impeded by Coulomb repulsion due to other electrons. This phenomenon causes a substantial reduction in the electron's kinetic energy, leading to remarkable experimental manifestations in optical spectroscopy. The high-transition-temperature (Tc) superconducting cuprates are perhaps the most studied examples of such correlated metals. The occurrence of high-Tc superconductivity in the iron pnictides puts a spotlight on the relevance of correlation effects in these materials. Here, we present an infrared and optical study on single crystals of the iron pnictide superconductor LaFePO. We find clear evidence of electronic correlations in metallic LaFePO with the kinetic energy of the electrons reduced to half of that predicted by band theory of nearly free electrons. We deduce that electronic many-body effects are important in the iron pnictides despite the absence of a Mott transition.
Transverse correlations in multiphoton entanglement
Wen Jianming; Rubin, Morton H.; Shih Yanhua
2007-10-15
We have analyzed the transverse correlation in multiphoton entanglement. The generalization of quantum ghost imaging is extended to the N-photon state. The Klyshko's two-photon advanced-wave picture is generalized to the N-photon case.
Modernizing the JPL VLBI Correlator
NASA Astrophysics Data System (ADS)
Rogstad, S.; Goodhart, C. E.; Clark, J. E.; Finley, S.; Lanyi, G. E.; White, L. A.; Jacobs, Christopher S.>
This poster will present the current capabilities of the JPL VLBI Correlator (JVC) and the general architecture of the equipment. In addition, the scientific and navigation uses of the JVC will be enumerated for background purposes. The JVC is a software correlator based on a Beowulf cluster of computers. It replaces a thirty year old correlator based on custom designed digital hardware. General comparisons between the old and new equipment will be made. The JVC makes use of a separate program, SoftC, to do the actual correlations. The JVC manages the sending of data to multiple machines in a Beowulf cluster each running SoftC in parallel on small chunks of the data. The basic architecture of SoftC will also be described.
Set Correlation and Contingency Tables.
ERIC Educational Resources Information Center
Cohen, Jacob
1988-01-01
Set correlation is explored as an option in analysis of two-way contingency tables. It includes measures of strength of association, significance tests and estimation, power analysis, and computer programs. (SLD)
Digital correlator with fewer IC's
NASA Technical Reports Server (NTRS)
Apple, G. G.; Rubin, L.
1979-01-01
Digital correlator requires only few integrated circuits to determine synchronization of two 24-bit digital words. Circuit is easily reduced or expanded to accommodate shorter or longer words and can be utilized in industrial and commercial data processing and telecommunications.
Glassy correlations in nematic elastomers
NASA Astrophysics Data System (ADS)
Lu, Bing; Goldbart, Paul; Mao, Xiaoming
2009-03-01
We address the physical properties of an isotropic melt or solution of nematogenic polymers that is then cross-linked beyond the vulcanization point. To do this, we construct a replica Landau theory involving a coupled pair of order- parameter fields: one describing vulcanization, the other describing local nematic order. Thermal nematic fluctuations, present at the time of cross-linking, are trapped by cross- linking into the vulcanized network. The resulting glassy nematic fluctuations are analyzed in the Gaussian approximation in two regimes. When the localization length is shorter than the thermal nematic correlation length, the nematic correlations are well captured as glassy correlations. In the opposite regime, fluctuations in the positions of the localized polymers partially wash out the glassy nematic correlations.
Local Realism of Macroscopic Correlations
NASA Astrophysics Data System (ADS)
Ramanathan, R.; Paterek, T.; Kay, A.; Kurzy?ski, P.; Kaszlikowski, D.
2011-08-01
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
ZHOU, XU; LU, JUN; ZHU, HUAQIANG
2016-01-01
The aim of the present study was to detect the expression levels of the human telomerase reverse transcriptase (hTERT) gene in hepatocellular carcinoma (HCC), and investigate its significance in the incidence and development of the cancer. HCC tissues and corresponding para-carcinoma liver tissues were surgically collected from 78 patients with HCC who presented to Shandong Provincial Hospital (Jinan, Shandong, China). hTERT expression at the protein and mRNA levels were detected by immunohistochemistry (streptavidin peroxidase method) and reverse transcription polymerase chain reaction, respectively, in the HCC tissues and corresponding para-carcinoma liver tissues of 78 HCC patients and in 12 samples of normal liver tissue. The data were analyzed using SPSS 17.0 statistical software, and employing ?2 tests and t-tests. hTERT protein was mainly expressed in the HCC cell cytoplasm, but was occasionally observed in the cell nucleus. The positive rates of hTERT protein and mRNA expression in the HCC patients were 84.62% (66/78) and 78.21% (61/78), respectively, which was significantly higher compared with the rates of 10.26% (8/78) and 8.97% (7/78) in the paired para-carcinoma liver tissues (P<0.01). hTERT protein and mRNA were not expressed in the normal liver tissues (0/12). ?2 test and t-test analysis revealed that hTERT gene expression was correlated with tumor grade, the presence/absence of a portal vein tumor thrombus, hepatitis B surface antigen positivity and a high ?-fetoprotein level (P<0.05) rather than patient age, gender or tumor size. Expression of the hTERT gene may play a pivotal role in the incidence and development of HCC. The hTERT gene potentially serves as an important molecular and biological index for diagnosing and predicating the biological behavior of HCC. PMID:26870177
Nonglobal correlations in collider physics
Moult, Ian; Larkoski, Andrew J.
2016-01-13
Despite their importance for precision QCD calculations, correlations between in- and out-of-jet regions of phase space have never directly been observed. These so-called non-global effects are present generically whenever a collider physics measurement is not explicitly dependent on radiation throughout the entire phase space. In this paper, we introduce a novel procedure based on mutual information, which allows us to isolate these non-global correlations between measurements made in different regions of phase space. We study this procedure both analytically and in Monte Carlo simulations in the context of observables measured on hadronic final states produced in e+e- collisions, though itmoreÂ Â» is more widely applicable.The procedure exploits the sensitivity of soft radiation at large angles to non-global correlations, and we calculate these correlations through next-to-leading logarithmic accuracy. The bulk of these non-global correlations are found to be described in Monte Carlo simulation. They increase by the inclusion of non-perturbative effects, which we show can be incorporated in our calculation through the use of a model shape function. As a result, this procedure illuminates the source of non-global correlations and has connections more broadly to fundamental quantities in quantum field theory.Â«Â less
Nonglobal correlations in collider physics
NASA Astrophysics Data System (ADS)
Larkoski, Andrew J.; Moult, Ian
2016-01-01
Despite their importance for precision QCD calculations, correlations between in- and out-of-jet regions of phase space have never directly been observed. These so-called nonglobal effects are present generically whenever a collider physics measurement is not explicitly dependent on radiation throughout the entire phase space. In this paper, we introduce a novel procedure based on mutual information, which allows us to isolate these nonglobal correlations between measurements made in different regions of phase space. We study this procedure both analytically and in Monte Carlo simulations in the context of observables measured on hadronic final states produced in e+e- collisions, though it is more widely applicable. The procedure exploits the sensitivity of soft radiation at large angles to nonglobal correlations, and we calculate these correlations through next-to-leading logarithmic accuracy. The bulk of these nonglobal correlations are found to be described in Monte Carlo simulation. They increase by the inclusion of nonperturbative effects, which we show can be incorporated in our calculation through the use of a model shape function. This procedure illuminates the source of nonglobal correlations and has connections more broadly to fundamental quantities in quantum field theory.
The Murchison Widefield Array Correlator
NASA Astrophysics Data System (ADS)
Ord, S. M.; Crosse, B.; Emrich, D.; Pallot, D.; Wayth, R. B.; Clark, M. A.; Tremblay, S. E.; Arcus, W.; Barnes, D.; Bell, M.; Bernardi, G.; Bhat, N. D. R.; Bowman, J. D.; Briggs, F.; Bunton, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; deSouza, L.; Ewell-Wice, A.; Feng, L.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Herne, D.; Hewitt, J. N.; Hindson, L.; Hurley-Walker, N.; Jacobs, D.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kincaid, B. B.; Koenig, R.; Kratzenberg, E.; Kudryavtseva, N.; Lenc, E.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Offringa, A.; Pathikulangara, J.; Pindor, B.; Prabu, T.; Procopio, P.; Remillard, R. A.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Salah, J. E.; Sault, R. J.; Udaya Shankar, N.; Srivani, K. S.; Stevens, J.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wyithe, J. S. B.
2015-03-01
The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio-astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day-1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
Computable measure of quantum correlation
NASA Astrophysics Data System (ADS)
Akhtarshenas, S. Javad; Mohammadi, Hamidreza; Karimi, Saman; Azmi, Zahra
2015-01-01
A general state of an system is a classical-quantum state if and only if its associated -correlation matrix (a matrix constructed from the coherence vector of the party , the correlation matrix of the state, and a function of the local coherence vector of the subsystem ), has rank no larger than . Using the general Schatten -norms, we quantify quantum correlation by measuring any violation of this condition. The required minimization can be carried out for the general -norms and any function of the local coherence vector of the unmeasured subsystem, leading to a class of computable quantities which can be used to capture the quantumness of correlations due to the subsystem . We introduce two special members of these quantifiers: The first one coincides with the tight lower bound on the geometric measure of discord, so that such lower bound fully captures the quantum correlation of a bipartite system. Accordingly, a vanishing tight lower bound on the geometric discord is a necessary and sufficient condition for a state to be zero-discord. The second quantifier has the property that it is invariant under a local and reversible operation performed on the unmeasured subsystem, so that it can be regarded as a computable well-defined measure of the quantum correlations. The approach presented in this paper provides a way to circumvent the problem with the geometric discord. We provide some examples to exemplify this measure.
Amit, Priyadarshi; Malhotra, Atul; Kumar, Rahul; Kumar, Lokesh; Patro, Dilip Kumar; Elangovan, Sundar
2015-01-01
Objectives: Preoperative chemotherapy plays a key role in management of bone sarcomas. Postoperative evaluation of histological necrosis has been the gold standard method of assessing response to preoperative chemotherapy. This study was done to evaluate the efficacy of static and dynamic magnetic resonance imaging (MRI) for assessing response preoperatively. Materials and Methods: Our study included 14 patients (12 osteosarcomas and 2 malignant fibrous histiocytomas) with mean age of 21.8 years, treated with preoperative chemotherapy followed by surgery. They were evaluated with static and dynamic MRI twice, before starting chemotherapy and again prior to surgery. Change in tumor volume and slope of signal intensity - time curve were calculated and correlated with percentage of histological necrosis using Pearson correlation test. Results: The change in dynamic MRI slope was significant (P = 0.001). Also, ?60% reduction in slope of the curve proved to be an indicator of good histological response [positive predictive value (PPV) =80%]. Change in tumor volume failed to show significant correlation (P = 0.071). Although it showed high negative predictive value (NPV = 85.7%), PPV was too low (PPV = 57.14%). Conclusions: Dynamic MRI correctly predicts histological necrosis after administration of preoperative chemotherapy to bone sarcomas. Hence, it can be used as a preoperative indicator of response to neoadjuvant chemotherapy. On the other hand, volumetric assessment by static MRI is not an effective predictor of histological necrosis. This study proves the superiority of dynamic contrast-enhanced study over volumetric study by MRI. PMID:26288521
NASA Astrophysics Data System (ADS)
Adjorlolo, Clement; Mutanga, Onisimo; Cho, Moses A.; Ismail, Riyad
2013-04-01
In this paper, a user-defined inter-band correlation filter function was used to resample hyperspectral data and thereby mitigate the problem of multicollinearity in classification analysis. The proposed resampling technique convolves the spectral dependence information between a chosen band-centre and its shorter and longer wavelength neighbours. Weighting threshold of inter-band correlation (WTC, Pearson's r) was calculated, whereby r = 1 at the band-centre. Various WTC (r = 0.99, r = 0.95 and r = 0.90) were assessed, and bands with coefficients beyond a chosen threshold were assigned r = 0. The resultant data were used in the random forest analysis to classify in situ C3 and C4 grass canopy reflectance. The respective WTC datasets yielded improved classification accuracies (kappa = 0.82, 0.79 and 0.76) with less correlated wavebands when compared to resampled Hyperion bands (kappa = 0.76). Overall, the results obtained from this study suggested that resampling of hyperspectral data should account for the spectral dependence information to improve overall classification accuracy as well as reducing the problem of multicollinearity.
Verma, KG; Verma, P; Bansal, N; Basavaraju, S; Sachdeva, SK; Khosa, R
2014-01-01
Background: Palatal rugae (PR) are asymmetrical irregular elevations, recorded during maxillary cast fabrication, that can be used for identification purpose if previous comparative sources are available. Aim: This study investigated uniqueness of PR patterns in relation to gender, palatal vault forms, and ABO blood groups in three (North-East [N-E], Northern and Western) populations of India. Subjects and Methods: The study was conducted on randomly selected 90 students, 30 from each sub population. Design - The palatal vault was recorded as Types I, II, and III. The maxillary casts were analyzed for each subject. The blood group of each subject was also recorded. Pearson's correlation coefficient tests were performed on cross-tabulations to evaluate significant relationship among different variables. Results: The PR number was more among females with an insignificant correlation among gender and mean rugae size on both sides. Types I and II hard palate vaults were seen associated with straight forwardly directed PR pattern, while Type III with curved forwardly directed PR. On the right side, straight rugae shape was most common type. On the left side, straight rugae shape was most common in Northern population while in N-E and Western populations curved rugae was the dominating type. A highly significant correlation was found between ABO blood groups and different PR patterns. Conclusions: PR possesses unique characteristics and can be used along with palatal vault forms as well as ABO blood groups for racial and individualistic soft tissue oral print in forensic cases. PMID:25328791
Weyand, Sabine; Chau, Tom
2015-01-01
Brain-computer interfaces (BCIs) provide individuals with a means of interacting with a computer using only neural activity. To date, the majority of near-infrared spectroscopy (NIRS) BCIs have used prescribed tasks to achieve binary control. The goals of this study were to evaluate the possibility of using a personalized approach to establish control of a two-, three-, four-, and five-class NIRS-BCI, and to explore how various user characteristics correlate to accuracy. Ten able-bodied participants were recruited for five data collection sessions. Participants performed six mental tasks and a personalized approach was used to select each individual's best discriminating subset of tasks. The average offline cross-validation accuracies achieved were 78, 61, 47, and 37% for the two-, three-, four-, and five-class problems, respectively. Most notably, all participants exceeded an accuracy of 70% for the two-class problem, and two participants exceeded an accuracy of 70% for the three-class problem. Additionally, accuracy was found to be strongly positively correlated (Pearson's) with perceived ease of session (??=?0.653), ease of concentration (??=?0.634), and enjoyment (??=?0.550), but strongly negatively correlated with verbal IQ (??=?-0.749). PMID:26483657
Bousquet, Jean; Zuberbier, Torsten; Canonica, G Walter; Fokkens, Wytske J; Gopalan, Gokul; Shekar, Tulin
2013-01-01
Allergic rhinitis (AR) symptoms can impart emotional, quality of life (QOL), and work productivity burdens, especially in persistent AR (PER). Desloratadine, an H1-receptor antagonist, has been shown to be effective against nasal and nonnasal AR symptoms and to improve QOL. Exploratory analyses were conducted to evaluate whether desloratadine-mediated symptom improvement correlated with improvements in QOL and productivity. The Aerius Control: Clinical and Evaluative Profile of Treatment 2 (NCT00405964) study was a 12-week, multinational, randomized, placebo-controlled prospective study of once-daily desloratadine at 5 mg in subjects with moderate-to-severe PER. Assessments included twice-daily symptom severity ratings (0 = none to 3 = severe; total and individual symptoms), sleep interference (morning [A.M.]), interference with activities of daily living (ADL; evening [P.M.]), the Rhinoconjunctivitis Quality of Life Questionnaire-Standardized version (baseline and days 29 and 85), and the Work Productivity and Activity Impairment-Allergy-Specific questionnaire (baseline and weekly). Pearson product-moment correlation statistics (r) were determined to assess correlations between symptom score improvements and QOL factors. All desloratadine-treated patients (n = 360) were included in this exploratory analysis. In the desloratadine-treated patients, all correlations tested were positive (all p < 0.0001). The highest coefficients were seen for the correlations between A.M./P.M. PRIOR total five-symptom score and interference with ADL (r = 0.72) and between A.M. NOW congestion and ADL interference (r = 0.69). Continuous daily treatment of moderate-to-severe PER with desloratadine at 5 mg/day significantly improved symptoms, which correlated positively, albeit moderately, with QOL benefits and reversal of functional impairments caused by PER. PMID:23676577
Friedman, Scott D.; Sonnentrucker, Paule; York, Donald G.; Hobbs, L. M.; McCall, Benjamin J.; Dahlstrom, Julie; Welty, Daniel E.; Drosback, Meredith M.; Rachford, Brian L.; Snow, Theodore P.
2011-01-20
We establish correlations between equivalent widths of eight diffuse interstellar bands (DIBs), and examine their correlations with atomic hydrogen, molecular hydrogen, and E{sub B-V}. The DIBs are centered at {lambda}{lambda} 5780.5, 6204.5, 6283.8, 6196.0, 6613.6, 5705.1, 5797.1, and 5487.7, in decreasing order of Pearson's correlation coefficient with N(H) (here defined as the column density of neutral hydrogen), ranging from 0.96 to 0.82. We find the equivalent width (EW) of {lambda}5780.5 is better correlated with column densities of H than with E{sub B-V} or H{sub 2}, confirming earlier results based on smaller data sets. We show that the same is true for six of the seven other DIBs presented here. Despite this similarity, the eight strong DIBs chosen are not correlated well enough with each other to suggest they come from the same carrier. We further conclude that these eight DIBs are more likely to be associated with H than with H{sub 2}, and hence are not preferentially located in the densest, most UV shielded parts of interstellar clouds. We suggest that they arise from different molecules found in diffuse H regions with very little H{sub 2} (molecular fraction f < 0.01). Of the 133 stars with available data in our study, there are three with significantly weaker {lambda}5780.5 than our mean H-{lambda}5780.5 relationship, all of which are in regions of high radiation fields, as previously noted by Herbig. The correlations will be useful in deriving interstellar parameters when direct methods are not available. For instance, with care, the value of N(H) can be derived from W{sub {lambda}}(5780.5).
Epithelial ovarian tumors: Clinicopathological correlation and immunohistochemical study
Naik, Pooja S.; Deshmukh, Sanjay; Khandeparkar, Siddhi Gaurish Sinai; Joshi, Avinash; Babanagare, Shridhar; Potdar, Jyostna; Risbud, Neelesh Sharad
2015-01-01
Background: Ovarian cancer is the third leading site of cancer among women, trailing behind cervix and breast cancer. Aim: This study was undertaken to analyze the immunohistochemical (IHC) profile of estrogen receptors (ER), progesterone receptors (PR), Ki-67, and p53 in various ovarian epithelial tumors and attempt correlation with clinical and histopathological findings. Materials and Methods: The present study was conducted over a period of 4 years. A technique of manual tissue array was employed for cases subjected for IHC. The primary antibodies used were ER, PR, p53, and Ki-67. A correlation was attempted between histopathological and IHC findings. Results were subjected to statistical analysis. Software program “the primer of biostatistics 5.0” was used for calculation of interrelationships between the analyzed ER, PR, p53, and Ki-67 expression and histological factors by Pearson's Chi-square test. The results were considered to be significant when the P < 0.05. Results: There were 110 cases of surface epithelial ovarian tumors (SEOT) encountered over the period of 4 years. The expression of ER was more in malignant tumors (13/16, 81.25%) than borderline (9/12, 75%) and benign (20/82, 24.39%). As compared to ER, the expression of PR was more in benign (51/82, 62.19%) than borderline (8/12, 66.67%) and malignant tumors (9/16, 56.25%). The expression of PR was more in benign tumors than borderline and malignant tumors. However, this was not statistically significant (Chi-square = 0.335 with 2 degrees of freedom; P = 0.846). The expression of p53 was less in benign (5/82, 6.1%) than borderline (9/12, 75%) and malignant tumors (13/16, 81.25%). The expression of Ki-67 was more in malignant (4/82, 4.88%) than borderline (10/12, 83.33%) and benign tumors (15/16, 93.75%). In all the above cases, the difference was statistically significant (P < 0.05). There was statistically significant difference in the expression of ER, PR, p53, and Ki-67 in the patients with age <40 years and above 40 years (P = 0.912). A positive correlation was observed in p53 expression and tumor grade. Similar correlation was seen in Ki-67 and tumor grade. It was also noted that mean Ki-67 labeling index (Li) had also increased with tumor grade. In the case of serous tumors, ER was expressed in all high- and low-grade tumors. The expression of PR was more in low-grade tumors than high-grade ones. P53 expression was seen in all high-grade tumors and 33.34% of low-grade tumor. The Ki-67 Li was more in high-grade tumors than low-grade tumors. Expression of ER, p53, and Ki-67 was higher in tumor showing metastasis. The mean Ki-67 Li was also higher in metastasizing tumors. However, PR expression was less in metastasizing tumors than nonmetastasizing tumors. Conclusion: IHC marker report of ER, PR status, and Ki-67 if included in each pathology report will pave the way for better understanding of biological behavior and modify treatment strategies.
Moio, Mariagrazia; Schonauer, Fabrizio
2015-08-01
Breast hypertrophy is often associated with functional limitations. Beyond the aesthetic concerns, breast reduction can improve symptoms and self-esteem. In different countries, health-care system regulations have fixed the threshold for reimbursement in 500 g of predicted tissue resection for each breast. Different preoperative measurements have been proposed to predict breast-tissue weight to be removed, showing a variable correlation with post-operative evaluation. We describe a reliable, simple measurement to predict the quantity of breast reduction in grams, which can be applicable to any surgical technique. A total of 128 patients undergoing bilateral breast reduction were evaluated. The correlation between the preoperative nipple-areola complex (NAC) lift distance and the weight of removed breast tissue was tested with linear regression and Pearson's test. Other anthropometric measurements were tested as a control. The ratio between resected grams and lift distance was explored to find a multiplication coefficient to be used at preoperative planning. The mean resection weight was 686.65 g. The mean NAC-lift distance was 7.6 cm. Positive correlation between the NAC-lift distance and the weight of breast tissue removed was found (r: 0.87; p < 0.001). The mean weight of the removed breast tissue (g) per centimetre of NAC lift was 81 g/cm in the group between 6 and 12 cm and 70 g/cm in the group with >12 cm of lift distance. The NAC-lift distance is a single, objective, repeatable measure that can provide a reliable prediction of breast-tissue grams to be removed; it helps in classifying breast-reduction indications. PMID:25997557
Higher plasma level of STIM1, OPG are correlated with stent restenosis after PCI
Li, Haibin; Jiang, Zhian; Liu, Xiangdong; Yang, Zhihui
2015-01-01
Object: Percutaneous Coronary Intervention (PCI) is one of the most effective treatments for Coronary Heart Disease (CHD), but the high rate of In Stent Restenosis (ISR) has plagued clinicians after PCI. We aim to investigate the correlation of plasma Stromal Interaction Molecular 1 (STIM1) and Osteoprotegerin (OPG) level with stent restenosis after PCI. Methods: A total of 100 consecutive patients with Coronary Heart Disease (CHD) received PCI procedure were recruited. Coronary angiography was performed 8 months after their PCI. Then patients were divided into 2 groups: observation group was composed by patients who existing postoperative stenosis after intervention; Control group was composed by patients with no postoperative stenosis. The plasma levels of STIM, OPG in all patients were tested before and after intervention. Pearson correlation and multiple linear regression analysis were performed to analysis the correlation between STIM, OPG level and postoperative stenosis. Results: 35 cases were divided into observation group and other 65 were divided into control group. The plasma levels of STIM, OPG have no statistical difference before their PCI procedure, but we observed higher level of High-sensitivity C-reactive protein (Hs-CRP) existed in observation group. We observed higher level of plasma STIM, OPG in observation group when compared with control group after PCI procedure (P < 0.05). Regression analysis demonstrated that Hs-CRP, STIM1, OPG are independent risk factors for ISR. Conclusion: Elevated levels of plasma STIM1, OPG are independent risk factors for ISR in patients received PCI, which could provide useful information for the restenosis control after PCI. PMID:26885040
High Blood Glucose Levels Correlate with Tumor Malignancy in Colorectal Cancer Patients
Cui, Ge; Zhang, Ting; Ren, Fan; Feng, Wen-Ming; Yao, Yunliang; Cui, Jie; Zhu, Guo-Liang; Shi, Qi-Lin
2015-01-01
Background Research shows that type 2 diabetes mellitus (T2DM) affects the risk and prognosis of colorectal cancer (CRC). Here, we conducted a retrospective study to investigate whether the clinicopathological features of CRC patients correlate with their blood glucose levels. Material/Methods We enrolled 391 CRC patients hospitalized in our center between 2008 and 2013. Data of their first fasting plasma glucose (FPG) and 2-h postprandial glucose (2hPPG) level after admission, their clinicopathological features, and survival were collected. The correlations between blood glucose level and clinicopathological features were analyzed by Pearson chi-square analysis. Patient survival was analyzed by Kaplan-Meier and Cox-regression analysis. Results There were 116 out of the 391 CRC patients who had high blood glucose level (H-G group, 29.67%), among which 58 (14.83%), 18 (4.60%), and 40 (10.23%) were diabetes mellitus (DM), impaired glucose tolerance (IGT), and impaired fasting glucose (IFG), respectively, while 275 (70.33%) patients had normal glucose level (N-G group). Compared with the N-G group, patients in the H-G group had larger tumor diameters and lower tumor differentiation (p<0.05). A higher ratio of patients in the H-G group also had more advanced TNM staging and more ulcerative CRC gross type (p<0.05). No significant difference was observed in patient overall survival among different glucose groups. No effect of insulin therapy on CRC development and patient survival was observed. Conclusions Blood glucose level in CRC patients correlates significantly with local tumor malignancy, but no significant effect on distant metastasis and patient overall survival was observed. PMID:26644185
Electronic correlations in Hund metals
NASA Astrophysics Data System (ADS)
Fanfarillo, L.; Bascones, E.
2015-08-01
To clarify the nature of correlations in Hund metals and its relationship with Mott physics we analyze the electronic correlations in multiorbital systems as a function of intraorbital interaction U , Hund's coupling JH, and electronic filling n . We show that the main process behind the enhancement of correlations in Hund metals is the suppression of the double occupancy of a given orbital, as it also happens in the Mott insulator at half-filling. However, contrary to what happens in Mott correlated states the reduction of the quasiparticle weight Z with JH can happen in spite of increasing charge fluctuations. Therefore, in Hund metals the quasiparticle weight and the mass enhancement are not good measurements of the charge localization. Using simple energetic arguments we explain why the spin polarization induced by Hund's coupling produces orbital decoupling. We also discuss how the behavior at moderate interactions, with correlations controlled by the atomic spin polarization, changes at large U and JH due to the proximity to a Mott insulating state.
Recirculating cross-correlation detector
Andrews, W.H. Jr.; Roberts, M.J.
1985-01-18
A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.
Community Detection for Correlation Matrices
NASA Astrophysics Data System (ADS)
MacMahon, Mel; Garlaschelli, Diego
2015-04-01
A challenging problem in the study of complex systems is that of resolving, without prior information, the emergent, mesoscopic organization determined by groups of units whose dynamical activity is more strongly correlated internally than with the rest of the system. The existing techniques to filter correlations are not explicitly oriented towards identifying such modules and can suffer from an unavoidable information loss. A promising alternative is that of employing community detection techniques developed in network theory. Unfortunately, this approach has focused predominantly on replacing network data with correlation matrices, a procedure that we show to be intrinsically biased because of its inconsistency with the null hypotheses underlying the existing algorithms. Here, we introduce, via a consistent redefinition of null models based on random matrix theory, the appropriate correlation-based counterparts of the most popular community detection techniques. Our methods can filter out both unit-specific noise and system-wide dependencies, and the resulting communities are internally correlated and mutually anticorrelated. We also implement multiresolution and multifrequency approaches revealing hierarchically nested subcommunities with "hard" cores and "soft" peripheries. We apply our techniques to several financial time series and identify mesoscopic groups of stocks which are irreducible to a standard, sectorial taxonomy; detect "soft stocks" that alternate between communities; and discuss implications for portfolio optimization and risk management.
Generalized minimum miscibility pressure correlation
Glaso, O.
1984-03-01
Correlations for predicting minimum miscibility pressure (MMP) are important tools in the selection of candidate reservoirs for gas miscible flooding. It is important that such correlations be accurate. Several CO2 MMP correlations have been published. None of these can be used with enough confidence for final project design, but are useful for screening and preliminary work. Correlations published on CO2 miscible flooding show temperature to be the most important parameter, but they disagree with regard to the effect of oil type. Compared with CO2 miscible flooding, little has been published on high-pressure hydrocarbon gas miscible flooding, and no correlation is available for predicting MMP with lean hydrocarbon gases or nitrogen. In 1960, Benham and coworkers presented empirical curves from which miscibility conditions can be estimated for reservoir oils being displaced by rich gas within a pressure range of 1500 to 3000 psia. From Benham's data, the proposed equations have been derived for predicting MMP. These equations are a result of curve fitting Benham's data. 22 references.
Jet correlations - opportunities and pitfalls
NASA Astrophysics Data System (ADS)
Renk, Thorsten
2014-12-01
The simplest observables used to probe the interaction of hard partons with a QCD medium in ultrarelativistic heavy-ion collisions measure disappearance, such as the nuclear modification factor RAA. The information content of such observables is however limited. More differential information is obtained from triggered correlation observables where a trigger condition ensures that a hard event has taken place and the correlation of other objects in the event with the trigger contains information about the nature of parton-medium interaction. By construction, triggered correlation observables are conditional probabilities, i.e. they measure events biased by the trigger condition. The presence of this bias makes the interpretation of observables non-intuitive, but at the same time represents an opportunity to design future measurements to selectively probe particular physics. In this work, an overview over the four types of biases occurring in triggered hard correlation observables is given, followed by a study of current jet correlation phenomenology in the light of the preceding discussion.
Sajjadi, Moosa; Rassouli, Maryam; Bahri, Narges; Mohammadipoor, Fatemeh
2015-01-01
Background: Illness uncertainty is a source of a chronic and pervasive psychological stress for people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (PLWH), and largely affects their quality of life and the ability to cope with the disease. Based on the uncertainty in illness theory, the social support is one of the illness uncertainty antecedents, and influences the level of uncertainty perceived by patients. Aim: To examine uncertainty in PLWH and its correlation with social support in Iran. Materials and Methods: This cross-sectional correlational study was conducted with 80 PLWH presenting to AIDS Research Center, Tehran, Iran in 2013. The data collected using illness uncertainty and social support inventories were analyzed through Pearson's correlation coefficient, Spearman's correlation coefficient, and regression analysis. Results: The results showed a high level of illness uncertainty in PLWH and a negative significant correlation between perceived social support and illness uncertainty (P = 0.01, r = -0.29). Conclusion: Uncertainty is a serious aspect of illness experience in Iranian PLWH. Providing adequate, structured information to patients as well as opportunities to discuss their concerns with other PLWH and receive emotional support from their health care providers may be worthwhile. PMID:26009679
Nagle, Anna S.; Nageswaren, Ashok R.; Haridas, Balakrishna; Mast, T. D.
2014-01-01
Little is understood about the biomechanical changes leading to pelvic floor disorders such as stress urinary incontinence. In order to measure regional biomechanical properties of the pelvic floor muscles in vivo, a three dimensional (3D) strain tracking technique employing correlation of volumetric ultrasound images has been implemented. In this technique, local 3D displacements are determined as a function of applied stress and then converted to strain maps. To validate this approach, an in vitro model of the pubovisceral muscle, with a hemispherical indenter emulating the downward stress caused by intra-abdominal pressure, was constructed. Volumetric B-scan images were recorded as a function of indenter displacement while muscle strain was measured independently by a sonomicrometry system (Sonometrics). Local strains were computed by ultrasound image correlation and compared with sonomicrometry-measured strains to assess strain tracking accuracy. Image correlation by maximizing an exponential likelihood function was found more reliable than the Pearson correlation coefficient. Strain accuracy was dependent on sizes of the subvolumes used for image correlation, relative to characteristic speckle length scales of the images. Decorrelation of echo signals was mapped as a function of indenter displacement and local tissue orientation. Strain measurement accuracy was weakly related to local echo decorrelation. PMID:24900165
Wilens, Timothy E.; Adler, Lenard A.; Tanaka, Yoko; Xiao, Feng; D’Souza, Deborah N.; Gutkin, Stephen W.; Upadhyaya, Himanshu P.
2013-01-01
Background Attention-deficit/hyperactivity disorder (ADHD) and substance use disorder are often comorbid in adults. The effects of ADHD treatment on comorbid alcohol use disorder have not been extensively studied. Objective To assess correlates of ADHD and alcohol use outcomes in ADHD with comorbid alcohol use disorders, via a post-hoc exploratory subgroup analysis of a previously conducted, randomized, double-blind, placebo controlled study of recently abstinent adults. Methods Adults who had ADHD and alcohol use disorders and were abstinent for 4–30 days were randomized to daily atomoxetine 25–100 mg (mean final dose=89.9 mg) or placebo for 12 weeks. Changes in ADHD symptoms from baseline to endpoint were assessed using the ADHD Investigator Symptom Rating Scale (AISRS) total score, alcohol use by the timeline followback method, and alcohol cravings by the Obsessive Compulsive Drinking Scale. Results Of 147 subjects receiving atomoxetine (n=72) or placebo (n=75) in the primary study, 80 (54%) completed 12 weeks (n=32 atomoxetine; n=48 placebo). Improvements in ADHD symptoms on the AISRS correlated significantly with decreases in alcohol cravings (Pearson’s r=0.28; 95% confidence interval [CI]=0.11–0.43; p=0.002), and the correlation was most notable with atomoxetine (r=0.29; CI [0.04 – 0.51]; p=0.023) rather than with placebo (r=0.24; CI [0.00–0.46]; p=0.055). On-treatment drinking levels correlated with AISRS scores (r=0.12; CI [0.05 –0.19]; p=0.001). Relapse to alcohol abuse significantly correlated with worse ADHD symptoms on 15 of 18 items of the AISRS in the placebo group (p<0.05 for each). Conclusions No baseline predictor (other than degree of sobriety) of alcohol use or ADHD outcomes emerged. ADHD symptom improvements correlated significantly with reductions in alcohol cravings, and relapse to alcohol abuse correlated significantly with worsening of most ADHD symptoms in the placebo group, but not in the atomoxetine group. This post-hoc subgroup analysis is of a hypothesis-generating nature, and the generalizability of the findings may be limited by exclusion of adults with common ADHD comorbidities from the base study. Further, prospective clinical trials in larger and more heterogeneous patient populations are warranted to confirm or reject these preliminary associations. PMID:22029549
Detecting Differential and Correlated Protein Expression in Label-Free Shotgun Proteomics
Zhang, Bing; Verberkmoes, Nathan C; Langston, Michael A; Uberbacher, Edward C; Hettich, Robert {Bob} L; Samatova, Nagiza F
2006-01-01
Recent studies have revealed a relationship between protein abundance and sampling statistics, such as sequence coverage, peptide count, and spectral count, in label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) shotgun proteomics. The use of sampling statistics offers a promising method of measuring relative protein abundance and detecting differentially expressed or coexpressed proteins. We performed a systematic analysis of various approaches to quantifying differential protein expression in eukaryotic Saccharomycescerevisiaeand prokaryotic Rhodopseudomonaspalustrislabel free LC-MS/MS data. First, we showed that, among three sampling statistics, the spectral count has the highest technical reproducibility, followed by the less-reproducible peptide count and relatively nonreproducible sequence coverage. Second, we used spectral count statistics to measure differential protein expression in pairwise experiments using five statistical tests: Fisher's exact test, G-test, AC test, t-test, and LPE test. Given the S.cerevisiaedata set with spiked proteins as a benchmark and the false positive rate as a metric, our evaluation suggested that the Fisher's exact test, G-test, and AC test can be used when the number of replications is limited (one or two), whereas the t-test is useful with three or more replicates available. Third, we generalized the G-test to increase the sensitivity of detecting differential protein expression under multiple experimental conditions. Out of 1622 identified R.palustris proteins in the LC-MS/MS experiment, the generalized G-test detected 1119 differentially expressed proteins under six growth conditions. Finally, we studied correlated expression of these 1119 proteins by analyzing pairwise expression correlations and by delineating protein clusters according to expression patterns. Through pairwise expression correlation analysis, we demonstrated that proteins co-located in the same operon were much more strongly coexpressed than those from different operons. Combining cluster analysis with existing protein functional annotations, we identified six protein clusters with known biological significance. In summary, the proposed generalized G-test using spectral count sampling statistics is a viable methodology for robust quantification of relative protein abundance and for sensitive detection of biologically significant differential protein expression under multiple experimental conditions in label-free shotgun proteomics.
Sumich, Alex L; Matsudaira, Toshiko; Heasman, Bryony; Gow, Rachel V; Ibrahimovic, Almira; Ghebremeskel, Kebreab; Crawford, Michael A; Taylor, Eric
2013-06-01
Atypical fatty acid metabolism has been reported in attention deficit hyperactivity disorder (ADHD), however, its relationship with temperament in this population is unclear. The current study investigated the association between blood levels of fatty acids implicated in brain structure and function (omega-3, omega-6, omega-9) and personality traits of stability (neuroticism, conscientiousness and agreeableness) and plasticity (extraversion and openness). Twenty right-handed adolescent boys with ADHD completed a self-report NEO-FFI personality questionnaire, and had fatty acid content assessed from red blood using gas chromatography. Pearson's correlations showed no significant associations between omega-3 levels and personality. After correction for multiple comparisons, Adrenic Acid (C22:4n6) was inversely associated with stability. Oleic acid (C18:1n9) was positively associated with plasticity. Results are in line with a role of fatty acids in brain function. They suggest that those fatty acids that are involved in myelination (Adrenic, Oleic) have the strongest associations with temperament in adolescents with ADHD. PMID:23566869
Knezovi?, Nevenka J; Memi?, Mustafa; Mabi?, Mirela; Huremovi?, Jasna; Mikuli?, Ivanka
2014-12-01
The aim of this study was to determine the association of cardiovascular disease (CVD) of selected human subjects with the hardness of water they consume. Laboratory testing of physical and chemical parameters of water were made using standardized methods: Standard Methods 19th edn, 1995 (APHA, AWWA & WEF, Washington, DC), and ISO 7888:1985, ISO 10523:1998. Pearson's chi-squared test was used for the statistical analysis of data, with the significance level of 0.05. The obtained data were analysed using the statistical program SPSS 16.0. The study sample consisted of 1,021 individuals divided into two groups: soft water consumers, 603 individuals, and, hard water consumers, 618 individuals. Results indicate that a statistically significant (?(2) = 5.315; df = 1; p = 0.021) number of individuals with CVD drink soft water. The prevalence of CVD in the age group 45-60 years in the study area where soft water is consumed was 21.3% and in the study area where hard water is consumed the prevalence of CVD was 13.7%. The summary results indicate significant correlation between the prevalence of CVD in the population group who drink soft water. The value of the relative risk is 1.127. PMID:25473991
Analysis-preserving video microscopy compression via correlation and mathematical morphology.
Shao, Chong; Zhong, Alfred; Cribb, Jeremy; Osborne, Lukas D; O'Brien, E Timothy; Superfine, Richard; Mayer-Patel, Ketan; Taylor, Russell M
2015-12-01
The large amount video data produced by multi-channel, high-resolution microscopy system drives the need for a new high-performance domain-specific video compression technique. We describe a novel compression method for video microscopy data. The method is based on Pearson's correlation and mathematical morphology. The method makes use of the point-spread function (PSF) in the microscopy video acquisition phase. We compare our method to other lossless compression methods and to lossy JPEG, JPEG2000, and H.264 compression for various kinds of video microscopy data including fluorescence video and brightfield video. We find that for certain data sets, the new method compresses much better than lossless compression with no impact on analysis results. It achieved a best compressed size of 0.77% of the original size, 25Ă— smaller than the best lossless technique (which yields 20% for the same video). The compressed size scales with the video's scientific data content. Further testing showed that existing lossy algorithms greatly impacted data analysis at similar compression sizes. Microsc. Res. Tech. 78:1055-1061, 2015. Â© 2015 Wiley Periodicals, Inc. PMID:26435032
Correlations among Stress Parameters, Meat and Carcass Quality Parameters in Pigs
Dokmanovic, Marija; Baltic, Milan Z.; Duric, Jelena; Ivanovic, Jelena; Popovic, Ljuba; Todorovic, Milica; Markovic, Radmila; Pantic, Srdan
2015-01-01
Relationships among different stress parameters (lairage time and blood level of lactate and cortisol), meat quality parameters (initial and ultimate pH value, temperature, drip loss, sensory and instrumental colour, marbling) and carcass quality parameters (degree of rigor mortis and skin damages, hot carcass weight, carcass fat thickness, meatiness) were determined in pigs (n = 100) using Pearson correlations. After longer lairage, blood lactate (p<0.05) and degree of injuries (p<0.001) increased, meat became darker (p<0.001), while drip loss decreased (p<0.05). Higher lactate was associated with lower initial pH value (p<0.01), higher temperature (p<0.001) and skin blemishes score (p<0.05) and more developed rigor mortis (p<0.05), suggesting that lactate could be a predictor of both meat quality and the level of preslaughter stress. Cortisol affected carcass quality, so higher levels of cortisol were associated with increased hot carcass weight, carcass fat thickness on the back and at the sacrum and marbling, but also with decreased meatiness. The most important meat quality parameters (pH and temperature after 60 minutes) deteriorated when blood lactate concentration was above 12 mmol/L. PMID:25656214
Correlations among Stress Parameters, Meat and Carcass Quality Parameters in Pigs.
Dokmanovic, Marija; Baltic, Milan Z; Duric, Jelena; Ivanovic, Jelena; Popovic, Ljuba; Todorovic, Milica; Markovic, Radmila; Pantic, Srdan
2015-03-01
Relationships among different stress parameters (lairage time and blood level of lactate and cortisol), meat quality parameters (initial and ultimate pH value, temperature, drip loss, sensory and instrumental colour, marbling) and carcass quality parameters (degree of rigor mortis and skin damages, hot carcass weight, carcass fat thickness, meatiness) were determined in pigs (n = 100) using Pearson correlations. After longer lairage, blood lactate (p<0.05) and degree of injuries (p<0.001) increased, meat became darker (p<0.001), while drip loss decreased (p<0.05). Higher lactate was associated with lower initial pH value (p<0.01), higher temperature (p<0.001) and skin blemishes score (p<0.05) and more developed rigor mortis (p<0.05), suggesting that lactate could be a predictor of both meat quality and the level of preslaughter stress. Cortisol affected carcass quality, so higher levels of cortisol were associated with increased hot carcass weight, carcass fat thickness on the back and at the sacrum and marbling, but also with decreased meatiness. The most important meat quality parameters (pH and temperature after 60 minutes) deteriorated when blood lactate concentration was above 12 mmol/L. PMID:25656214
Unified theory of plasma correlations
NASA Astrophysics Data System (ADS)
Guillen, M. A.; Liboff, R. L.
1983-06-01
A unified approach to the theory of correlations in a plasma is presented, based on the BBKGY hierarchy. The theory is applied to a one-component plasma with the Coulomb interaction modified to include effects of the background. Closed integro-differential equations in space and time are obtained for the two-particle correlation function in both the strong and weak coupling limits. In the weak-coupling domain, gamma <<1, the time-independent analysis returns the well-known linearized Debye-Huckle result, where gamma is the plasma parameter. In the strong-coupling domain gamma >1, the resulting two-particle total correlation function exhibits decaying oscillatory behavior for particle separation of the order of the effective interparticle range.
Softc: An Operational Software Correlator
NASA Technical Reports Server (NTRS)
Lowe, Stephen T.
2004-01-01
Softc has been used operationally for spacecraft navigation at JPL for over 2 years and will be JPL's Mark 5 correlator next year. Softc was written to be as close to an ideal correlator as possible, making approximations only below 10(exp -13) seconds. The program can correlate real USB, real LSB, or complex I/Q data sampled with 1, 2, 4. or 8-bit resolution, and was developed with strong debugging tools that made final debugging relatively quick. Softc's algorithms and program structure are fully documented. Timing tests on a recent Intel CPU show Softc processes 8 lags of 1-bit sampled data at 10 MSamples/sec, independent of sample rate.
Sequence correlations shape protein promiscuity
NASA Astrophysics Data System (ADS)
Lukatsky, David B.; Afek, Ariel; Shakhnovich, Eugene I.
2011-08-01
We predict analytically that diagonal correlations of amino acid positions within protein sequences statistically enhance protein propensity for nonspecific binding. We use the term "promiscuity" to describe such nonspecific binding. Diagonal correlations represent statistically significant repeats of sequence patterns where amino acids of the same type are clustered together. The predicted effect is qualitatively robust with respect to the form of the microscopic interaction potentials and the average amino acid composition. Our analytical results provide an explanation for the enhanced diagonal correlations observed in hubs of eukaryotic organismal proteomes [J. Mol. Biol. 409, 439 (2011)], 10.1016/j.jmb.2011.03.056. We suggest experiments that will allow direct testing of the predicted effect.
Spatiotemporal correlations of aftershock sequences
NASA Astrophysics Data System (ADS)
Peixoto, Tiago P.; Doblhoff-Dier, Katharina; Davidsen, JöRn
2010-10-01
Aftershock sequences are of particular interest in seismic research because they may condition seismic activity in a given region over long time spans. Although they are typically identified with periods of enhanced seismic activity after a large earthquake as characterized by the Omori law, our knowledge of the spatiotemporal correlations between events in an aftershock sequence is limited. Here, we study the spatiotemporal correlations of two aftershock sequences form California (Parkfield and Hector Mine) using the recently introduced concept of "recurrent" events. We find that both sequences have very similar properties and that most of them are captured by the space-time epidemic-type aftershock sequence (ETAS) model if one takes into account catalog incompleteness. However, the stochastic ETAS model does not capture those spatiotemporal correlations that give rise to the observed distribution of recurrent events on small spatial scales. We also find that there is no clear evidence for stress shadows that have been observed for smaller earthquakes.
State estimation on correlated copies
NASA Astrophysics Data System (ADS)
Demkowicz-Dobrza?ski, Rafa?
2005-06-01
State estimation is usually analyzed in the situation when copies are in a product state, either mixed or pure. We investigate here the concept of state estimation on correlated copies. We analyze state estimation on correlated N -qubit states, which are permutationally invariant. Using a correlated state we try to estimate as good as possible the direction of the Bloch vector of a single-particle reduced density matrix. We derive the optimal fidelity for all permutation invariant states. We find the optimal state, which yields the highest estimation fidelity among the states with the same reduced density matrix. Interestingly, this state is not a product state. We also point out that states produced by optimal universal cloning machines are the worst, from the point of view of estimating the reduced density matrix.
Correlative Fluorescence and Electron Microscopy
Schirra, Randall T.; Zhang, Peijun
2014-01-01
Correlative fluorescence and electron microscopy (CFEM) is a multimodal technique that combines dynamic and localization information from fluorescence methods with ultrastructural data from electron microscopy, to give new information about how cellular components change relative to the spatiotemporal dynamics within their environment. In this review, we will discuss some of the basic techniques and tools of the trade for utilizing this attractive research method, which is becoming a very powerful tool for biology labs. The information obtained from correlative methods has proven to be invaluable in creating consensus between the two types of microscopy, extending the capability of each, and cutting the time and expense associate with using each method separately for comparative analysis. The realization of the advantages of these methods in cell biology have led to rapid improvement in the protocols and have ushered in a new generation of instruments to reach the next level of correlation â€“ integration. PMID:25271959
Correlated optical and isotopic nanoscopy
NASA Astrophysics Data System (ADS)
Saka, Sinem K.; Vogts, Angela; Kröhnert, Katharina; Hillion, François; Rizzoli, Silvio O.; Wessels, Johannes T.
2014-04-01
The isotopic composition of different materials can be imaged by secondary ion mass spectrometry. In biology, this method is mainly used to study cellular metabolism and turnover, by pulsing the cells with marker molecules such as amino acids labelled with stable isotopes (15N, 13C). The incorporation of the markers is then imaged with a lateral resolution that can surpass 100?nm. However, secondary ion mass spectrometry cannot identify specific subcellular structures like organelles, and needs to be correlated with a second technique, such as fluorescence imaging. Here, we present a method based on stimulated emission depletion microscopy that provides correlated optical and isotopic nanoscopy (COIN) images. We use this approach to study the protein turnover in different organelles from cultured hippocampal neurons. Correlated optical and isotopic nanoscopy can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures.
NASA Astrophysics Data System (ADS)
Lorcé, Cédric
2015-02-01
The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.
Correlation-Force-Spectroscopy Rheometer
NASA Astrophysics Data System (ADS)
Radiom, Milad; Robbins, Brian; Honig, Christopher D. F.; Walz, John Y.; Paul, Mark R.; Ducker, William A.
2011-11-01
We describe a new method, correlation force spectrometry, which characterizes fluids through measurement of the correlations between the thermally-stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss applications to measurement of the rheological properties of complex fluids at high frequency and high spatial resolution. We measure a large range of frequencies (up to 1 MHz) and use very small sample volumes (?L) and demonstrate that the thermal noise in the cross correlation is much smaller than in the autocorrelation. Our experimental measurements of the equilibrium fluctuations in cantilever displacement for cantilever pairs immersed in a Newtonian fluid are described accurately using a theoretical approach based upon the fluctuation-dissipation theorem [Paul and Cross, Phys. Rev. Lett. 92, 235501 (2004)]. The work described in this paper was funded by the National Science Foundation via Award Number CBET-0959228 and by Virginia Tech.
Correlation properties of loose groups
Maia, M.A.G.; Da Costa, L.N. )
1990-02-01
The two-point spatial correlation function for loose groups of galaxies is computed, using the recently compiled catalog of groups in the southern hemisphere. It is found that the correlation function for groups has a similar slope to that of galaxies but with a smaller amplitude, confirming an earlier result obtained from a similar analysis of the CfA group catalog. This implies that groups of galaxies are more randomly distributed than galaxies, which may be consistent with the predictions of Kashlinsky (1987) for a gravitational clustering scenario for the formation of large-scale structures. 21 refs.
Minimum Bayes risk image correlation
NASA Technical Reports Server (NTRS)
Minter, T. C., Jr.
1980-01-01
In this paper, the problem of designing a matched filter for image correlation will be treated as a statistical pattern recognition problem. It is shown that, by minimizing a suitable criterion, a matched filter can be estimated which approximates the optimum Bayes discriminant function in a least-squares sense. It is well known that the use of the Bayes discriminant function in target classification minimizes the Bayes risk, which in turn directly minimizes the probability of a false fix. A fast Fourier implementation of the minimum Bayes risk correlation procedure is described.
Statistical estimates of electron correlations
Gyorffy, W.; Henderson, Thomas M.; Greer, J. C.
2006-08-07
While arbitrarily accurate solutions to the many-body Schroedinger equation are possible through a brute force expansion of the wave function, the length of the expansions required renders the approach intractable except for few-electron problems. By considering the form of the energy resulting from truncation of the many-particle expansion space, it is shown that accurate determination of electron correlations may be extracted from estimates of average or effective energy contributions while maintaining a reduced dimension for the expansion space. An energy formula expressed as a rational function of the expansion vector length is determined, allowing for estimates of asymptotic limits of many-body correlations.
Reveal quantum correlation in complementary bases
Wu, Shengjun; Ma, Zhihao; Chen, Zhihua; Yu, Sixia
2014-01-01
An essential feature of genuine quantum correlation is the simultaneous existence of correlation in complementary bases. We reveal this feature of quantum correlation by defining measures based on invariance under a basis change. For a bipartite quantum state, the classical correlation is the maximal correlation present in a certain optimum basis, while the quantum correlation is characterized as a series of residual correlations in the mutually unbiased bases. Compared with other approaches to quantify quantum correlation, our approach gives information-theoretical measures that directly reflect the essential feature of quantum correlation. PMID:24503595
NASA Astrophysics Data System (ADS)
Boschi, L.; Becker, Thorsten W.; Steinberger, Bernhard
2008-04-01
In a recent article, [Boschi, L., Becker, T.W., Steinberger, B., 2007. Mantle plumes: dynamic models and seismic images. Geochem. Geophys. Geosyst. 8, Q10006. doi:10.1029/2007GC001733] (BBS07) have re-evaluated the degree to which slow seismic tomography anomalies correlate with the possible locations of plume-like mantle upwellings connected to surface hotspots. They showed that several, but not all, hotspots are likely to have a deep mantle origin. Importantly, they found that when advection of plume conduits in mantle flow is considered, such correlations are significantly higher than when conduits are assumed to be vertical under hotspots. The validity of these statements depends, however, on the definition of statistical significance. BBS07 evaluated the significance of correlation through simple Student's t tests. Anderson (personal communication, July 2007) questioned this approach, given that the true information content of published tomography models is generally unknown, and proposed, instead, to evaluate the significance of correlation by comparing tomographic results with Monte Carlo simulations of randomly located plumes. Following this approach, we show here that the correlation found by BBS07 between advected plumes and slow anomalies in S-velocity tomography is less significant than previously stated, but still significant (at the 99.7% confidence level). We also find an indication that the seismic/geodynamic correlation observed by BBS07 does not only reflect the natural tendency of plumes to cluster in slow/hot regions of the mantle: although realistically advected, and thereby biased towards such regions, our random plumes correlate with slow tomographic anomalies significantly less than the plume models of BBS07. A less significant correlation with plume models characterizes P-velocity tomography; the correlation is, however, enhanced, if flow is computed from tomographic models with amplified heterogeneity, possibly accounting for the known resolution limits of global seismic data. In summary, the conclusions of BBS07 are confirmed: even at relatively long wavelengths, tomographic models are consistent with the presence of a number of tilted, whole-mantle plume-shaped slow anomalies, connected to surface hotspots.
Correlation analysis of urine metabolites and clinical staging in patients with ovarian cancer
Jiang, Ting; Lin, Yunliang; Yin, Haiqin; Wang, Shanshan; Sun, Qinglei; Zhang, Peihai; Bi, Wenxiang
2015-01-01
This study is to investigate the correlation between urine metabolites and clinical staging in patients with ovarian cancer. The urina sanguinis from 56 cases of primary epithelial ovarian cancer patients and 15 healthy volunteers was collected and the urine metabolites were extracted. Ultra high performance liquid chromatography/time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis was performed. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to analyze the mass spectrometry data. Database retrieval and comparison of the screened metabolites were performed and one-way ANOVA and least significant difference (LSD) t test were carried out. PCA analysis of UPLC-Q-TOF-MS results showed that the score plots of samples from healthy people and patients with ovarian cancer at different clinical stages were separated. Further PLS-DA analysis significantly improved the classification results. The R2X was 0.757, the R2Y was 0.977 and the Q2Y was 0.87, indicating that the model stability and predictability were good. Eight metabolites, including N-acetylneuraminic acid-9-phosphate, 5’-methioadenosine, uric acid-3-nucleoside, pseudouridine, L-valine, succinic acid, L-proline and ?-nicotinamide mononucleotide were identified. The contents of these metabolites increased with the development of the disease. There was correlation between urine metabolites and clinical staging in patients with ovarian cancer.
Valizadeh, Solmaz; Shahbeig, Shahrzad; Mohseni, Sudeh; Azimi, Fateme; Bakhshandeh, Hooman
2015-01-01
Background: In orthodontic science, diagnosis of facial skeletal type (class I, II, and III) is essential to make the correct treatment plan that is usually expensive and complicated. Sometimes results from analysis of lateral cephalometry radiographies are not enough to discriminate facial skeletal types. In this situation, knowledge about the relationship between the shape and size of the sella turcica and the type of facial skeletal class can help to make a more definitive decision for treatment plan. Objectives: The present study was designed to investigate this relationship in patients referred to a dental school in Iran. Patients and Methods: In this descriptive-analytical study, cephalometric radiographies of 90 candidates for orthodontic treatment (44 females and 46 males) with an age range of 14 - 26 years and equal distribution in terms of class I, class II, and class III facial skeletal classification were selected. The shape, length, diameter, and depth of the sella turcica were determined on the radiographs. Linear dimensions were assessed by one-way analysis of variance while the correlation between the dimensions and age was investigated using Pearson’s correlation coefficient. Results: Sella turcica had normal morphology in 24.4% of the patients while irregularity (notching) in the posterior part of the dorsum sella was observed in 15.6%, double contour of sellar floor in 5.6%, sella turcica bridge in 23.3%, oblique anterior wall in 20% and pyramidal shape of the dorsum sella in 11.1% of the subjects. In total, 46.7% of class I patients had a normal shape of sella turcica, 23.3% of class II patients had an oblique anterior wall and a pyramidal shape of the dorsum sella, and 43.3% of class III individuals had sella turcica bridge (the greatest values). Sella turcica length was significantly greater in class III patients compared to class II and class I (P < 0.0001). However, depth and diameter of sella turcica were similar in class I, class II, and class III patients. Furthermore, age was significantly correlated to the diameter of sella turcica as greater diameters were observed in older ages (P < 0.04). Conclusion: A significant relationship exists between the type of facial skeletal classification and the shape of the sella turcica; as in class III patients, sella turcica bridge was reported with a higher frequency. Also, sella turcica had a significantly higher length in these patients than in those with class I and class II facial skeletal types. PMID:26557271
Compact coherent optical correlator system
NASA Astrophysics Data System (ADS)
Upatnieks, Juris; Abshier, James O.
1988-05-01
A real-time coherent optical correlator was designed, fabricated and tested. The correlator features 30 separate filters, low-light level real-time operation, and a compact design. The correlator is packaged in a cylinder 15 cm in diameter by 30 cm long, excluding imaging lens. Each of the two laser diode coherent light sources is imaged to 15 locations with holographic optical elements (HOEs). The HOEs perform a number of functions usually requiring several optical components. The HOEs correct the aspect ratio of the laser diode beams, perform the functions of collimating and Fourier transform lenses, multiplex the light beam to form multiple Fourier transforms, and correct a variety of system aberrations. Low-light operation is achieved with a microchannel image intensifier in front of a liquid crystal light modulator. This arrangement allows the correlator to operate over a wide range of light levels, from full sunlight to dusk. The image intensifier, however, reduces system resolution and response time. A computer controlled filter maker system was designed to automate filter recording. The computer, a small PC-type, controls the position of the recording plate, the reference beam angle, dwell and exposure times, and checks light source and shutter operation.
Correlated Tunneling in Hydrogen Bonds
NASA Astrophysics Data System (ADS)
Lin, Lin; Morrone, Joseph A.; Car, Roberto
2011-10-01
We study the quantum nature of the protons participating in hydrogen bonds in several ice structures by analyzing the one particle density matrix. We find that in all cases, including ice Ih, the most common form of ice, and the high pressure phases, ice VIII, VII, and X, the system is ground-state dominated. However, while the dynamics is uncorrelated in the structures with standard asymmetric hydrogen bonds, such as ice Ih and VIII, local correlations among the protons characterize ice VII and, to a lesser extent, ice X in the so-called low barrier hydrogen bond regime. The correlations appear along the path to hydrogen bond symmetrization, when quantum fluctuations delocalize the proton on the two bond sides. The correlations derive from a strong requirement for local charge neutrality that favors concerted motion along the bonds. The resulting behavior deviates substantially from mean field theory, which would predict in ice VII coherent tunneling of the proton between the two bond sides, thereby causing an ionization catastrophe. Due to the correlations, the quantum state of the proton is entangled.
Sample Size and Correlational Inference
ERIC Educational Resources Information Center
Anderson, Richard B.; Doherty, Michael E.; Friedrich, Jeff C.
2008-01-01
In 4 studies, the authors examined the hypothesis that the structure of the informational environment makes small samples more informative than large ones for drawing inferences about population correlations. The specific purpose of the studies was to test predictions arising from the signal detection simulations of R. B. Anderson, M. E. Doherty,…
Multilevel Modeling with Correlated Effects
ERIC Educational Resources Information Center
Kim, Jee-Seon; Frees, Edward W.
2007-01-01
When there exist omitted effects, measurement error, and/or simultaneity in multilevel models, explanatory variables may be correlated with random components, and standard estimation methods do not provide consistent estimates of model parameters. This paper introduces estimators that are consistent under such conditions. By employing generalizedâ€¦
Correlation-assisted quantum communication
Ziman, Mario; Buzek, Vladimir
2003-04-01
Quantum dense coding is considered to be one of the most remarkable demonstrations of the existence of quantum entanglement. In this paper, we analyze the role of correlations (both classical and quantum) in quantum communication protocols. We study how the capacity of a single-qubit quantum channel depends on correlations between Alice and Bob. In particular, we consider a scenario when Alice and Bob share a pair of qubits in a state such that Alice's qubit is in the state described by the density operator {rho}=(1/2)1+n-vector{center_dot}{sigma}-vector. We evaluate a capacity of the noiseless channel for two cases: (1) when Bob performs measurement just on the particle received from Alice, and (2) in the case when he utilizes correlations that have been established prior to the communication. We present a simple classical scenario which might serve as a prototype of quantum dense coding. We generalize our results also for qudits. In addition, we address some aspects of the issue of security in correlation-assisted communication protocols.
Octupole correlation effects in nuclei
Chasman, R.R.
1992-08-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Octupole correlation effects in nuclei
Chasman, R.R.
1992-01-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Multilevel Modeling with Correlated Effects
ERIC Educational Resources Information Center
Kim, Jee-Seon; Frees, Edward W.
2007-01-01
When there exist omitted effects, measurement error, and/or simultaneity in multilevel models, explanatory variables may be correlated with random components, and standard estimation methods do not provide consistent estimates of model parameters. This paper introduces estimators that are consistent under such conditions. By employing generalized…
Cognitive Correlates of Childhood Depression.
ERIC Educational Resources Information Center
Campbell-Goymer, Nancy R.
Many researchers and clinicians are diagnosing depressed children according to criteria resembling those used to diagnose depressed adults. To investigate cognitive correlates of depression in children two studies were conducted. In the first study 37 children in grades 5-7 were given a booklet containing the Children's Depression Inventory (CDI)…
Simplified Correlator For Ranging Codes
NASA Technical Reports Server (NTRS)
Tausworthe, R. C.; Smith, J. R.
1990-01-01
Improved correlating subsystem of pseudorandom-code ranging system made possible by advent of fast, custom-made, very-large-scale integrated circuits. Performs far fewer arithmetical operations, contains much less specialized analog and digital circuitry, and used with large number of different codes.
Correlation effects and bound states
Zinovjev, G. M.; Molodtsov, S. V.
2012-11-15
Bound states in a simple quark model that are due to correlation effects are analyzed. The confining properties of this model in meson (quark-antiquark and diquark) channels manifest themselves at any quark momenta, and an extra potential field may only enhance the confining effect.
Tetrachoric Correlation: A Permutation Alternative
ERIC Educational Resources Information Center
Long, Michael A.; Berry, Kenneth J.; Mielke, Paul W., Jr.
2009-01-01
An exact permutation test is provided for the tetrachoric correlation coefficient. Comparisons with the conventional test employing Student's t distribution demonstrate the necessity of using the permutation approach for small sample sizes and/or disproportionate marginal frequency totals. (Contains 4 tables.)
Time correlators from deferred measurements
NASA Astrophysics Data System (ADS)
Oehri, D.; Lebedev, A. V.; Lesovik, G. B.; Blatter, G.
2016-01-01
Repeated measurements that typically occur in two-time or multitime correlators rely on von Neumann's projection postulate, telling how to restart the system after an intermediate measurement. We invoke the principle of deferred measurement to describe an alternative procedure in which coevolving quantum memories extract system information through entanglement, combined with a final readout of the memories described by Born's rule. Our approach to repeated quantum measurements respects the unitary evolution of quantum mechanics during intermediate times, unifies the treatment of strong and weak measurements, and reproduces the projected and (anti)symmetrized correlators in the two limits. As an illustration, we apply our formalism to the calculation of the electron charge correlator in a mesoscopic physics setting, where single electron pulses assume the role of flying memory qubits. We propose an experimental setup that reduces the measurement of the time correlator to the measurement of currents and noise, exploiting the (pulsed) injection of electrons to cope with the challenge of performing short-time measurements.
Dynamics of electricity market correlations
NASA Astrophysics Data System (ADS)
Alvarez-Ramirez, J.; Escarela-Perez, R.; Espinosa-Perez, G.; Urrea, R.
2009-06-01
Electricity market participants rely on demand and price forecasts to decide their bidding strategies, allocate assets, negotiate bilateral contracts, hedge risks, and plan facility investments. However, forecasting is hampered by the non-linear and stochastic nature of price time series. Diverse modeling strategies, from neural networks to traditional transfer functions, have been explored. These approaches are based on the assumption that price series contain correlations that can be exploited for model-based prediction purposes. While many works have been devoted to the demand and price modeling, a limited number of reports on the nature and dynamics of electricity market correlations are available. This paper uses detrended fluctuation analysis to study correlations in the demand and price time series and takes the Australian market as a case study. The results show the existence of correlations in both demand and prices over three orders of magnitude in time ranging from hours to months. However, the Hurst exponent is not constant over time, and its time evolution was computed over a subsample moving window of 250 observations. The computations, also made for two Canadian markets, show that the correlations present important fluctuations over a seasonal one-year cycle. Interestingly, non-linearities (measured in terms of a multifractality index) and reduced price predictability are found for the June-July periods, while the converse behavior is displayed during the December-January period. In terms of forecasting models, our results suggest that non-linear recursive models should be considered for accurate day-ahead price estimation. On the other hand, linear models seem to suffice for demand forecasting purposes.
Ishikawa, Toru; Abe, Satoshi; Hoshii, Asami; Yamada, Yumi; Iiduka, Akihiko; Nemoto, Takeo; Takeda, Keiko; Yoshida, Toshiaki
2016-01-01
Background & Aims The amount of drug-loaded lipiodol in an HCC tumor post-transarterial chemoembolization (TACE) correlates with the risk of local tumor recurrence. Lipiodol enhancement of a tumor on conventional CT, measured in Hounsfield units (HU), can predict tumor response. Here we investigate whether cone-beam CT (CBCT) can also be used to predict tumor response, providing the benefit of being able to optimize the patient’s treatment plan intra-procedurally. Methods A total of 82 HCC nodules (82 patients), ?5 cm in diameter, were treated with balloon-occluded TACE using miriplatin between December 2013 and November 2014. For each patient, both CBCT and conventional CT images were obtained post-TACE. The degree of correlation between CBCT and conventional CT was determined by comparing identical regions of interest for each imaging modality using pixel values. Results The pixel values from conventional CT and CBCT were highly correlated, with a Pearson correlation coefficient of 0.912 (p<0.001). The location of the nodules within the liver did not affect the results; the correlation coefficient was 0.891 (p<0.001) for the left lobe and 0.926 (p<0.001) for the right lobe. The mean pixel value for conventional CT was 439 ± 279 HU, and the mean pixel value for CBCT was 416 ± 311 HU. Conclusions CBCT may be used as a substitute for conventional CT to quantitatively evaluate the amount of drug-loaded lipiodol within an HCC nodule and, hence, the efficacy of TACE treatment. The major benefit of using CBCT is the ability to predict the likelihood of local recurrence intra-procedurally, enabling subsequent treatment optimization. PMID:26752696
Strom, Suzanne L.; Anderson, Craig L.; Yang, Luanna; Canales, Cecilia; Amin, Alpesh; Lotfipour, Shahram; McCoy, C. Eric; Langdorf, Mark I.
2015-01-01
Introduction Traditional Advanced Cardiac Life Support (ACLS) courses are evaluated using written multiple-choice tests. High-fidelity simulation is a widely used adjunct to didactic content, and has been used in many specialties as a training resource as well as an evaluative tool. There are no data to our knowledge that compare simulation examination scores with written test scores for ACLS courses. Objective To compare and correlate a novel high-fidelity simulation-based evaluation with traditional written testing for senior medical students in an ACLS course. Methods We performed a prospective cohort study to determine the correlation between simulation-based evaluation and traditional written testing in a medical school simulation center. Students were tested on a standard acute coronary syndrome/ventricular fibrillation cardiac arrest scenario. Our primary outcome measure was correlation of exam results for 19 volunteer fourth-year medical students after a 32-hour ACLS-based Resuscitation Boot Camp course. Our secondary outcome was comparison of simulation-based vs. written outcome scores. Results The composite average score on the written evaluation was substantially higher (93.6%) than the simulation performance score (81.3%, absolute difference 12.3%, 95% CI [10.6–14.0%], p<0.00005). We found a statistically significant moderate correlation between simulation scenario test performance and traditional written testing (Pearson r=0.48, p=0.04), validating the new evaluation method. Conclusion Simulation-based ACLS evaluation methods correlate with traditional written testing and demonstrate resuscitation knowledge and skills. Simulation may be a more discriminating and challenging testing method, as students scored higher on written evaluation methods compared to simulation. PMID:26594288
Levinson, E M; Folino, L
1994-04-01
29 students (M age of 8.0 yr.) who were referred for evaluation were administered the Gifted Evaluation Scale, the Kaufman Brief Intelligence Test, and the WISC-III. Paired t tests comparing the mean GES Quotient with the K-BIT mean IQ and WISC-III Verbal, Performance, and Full Scale IQs yielded no statistically significant differences (range of IQs = 120.6 to 122.9). While the significant correlation of the GES Quotient and WISC-III Performance IQ was .42, r = -.37 for the GES Quotient and WISC-III Verbal IQ. No significant correlation was found between the GES Quotient and the WISC-III Full Scale or K-BIT IQs. The limitations and implications of the study, with regard to the use of the Gifted Evaluation Scale, are discussed. PMID:8197281
Automated Gait and Balance Parameters Diagnose and Correlate with Severity in Parkinson Disease
Dewey, Daniel C.; Miocinovic, Svjetlana; Bernstein, Ira; Khemani, Pravin; Dewey, Richard B.; Querry, Ross; Chitnis, Shilpa; Dewey, Richard B.
2014-01-01
Objective To assess the suitability of instrumented gait and balance measures for diagnosis and estimation of disease severity in PD. Methods Each subject performed iTUG (instrumented Timed-Up-and-Go) and iSway (instrumented Sway) using the APDM® Mobility Lab. MDS-UPDRS parts II and III, a postural instability and gait disorder (PIGD) score, the mobility subscale of the PDQ-39, and Hoehn & Yahr stage were measured in the PD cohort. Two sets of gait and balance variables were defined by high correlation with diagnosis or disease severity and were evaluated using multiple linear and logistic regressions, ROC analyses, and t-tests. Results 135 PD subjects and 66 age-matched controls were evaluated in this prospective cohort study. We found that both iTUG and iSway variables differentiated PD subjects from controls (area under the ROC curve was 0.82 and 0.75 respectively) and correlated with all PD severity measures (R2 ranging from 0.18 to 0.61). Objective exam-based scores correlated more strongly with iTUG than iSway. The chosen set of iTUG variables was abnormal in very mild disease. Age and gender influenced gait and balance parameters and were therefore controlled in all analyses. Interpretation Our study identified sets of iTUG and iSway variables which correlate with PD severity measures and differentiate PD subjects from controls. These gait and balance measures could potentially serve as markers of PD progression and are under evaluation for this purpose in the ongoing NIH Parkinson Disease Biomarker Program. PMID:25082782
Correlation of the interdental and the interradicular bone loss: A radiovisuographic analysis
Grover, Vishakha; Malhotra, Ranjan; Kapoor, Anoop; Mankotia, Chahat Singh; Bither, Rupika
2014-01-01
Background: Presence of furcation involvement indicates advanced periodontitis, and a potentially less-favorable prognosis, for the affected tooth and its diagnosis has always been an enigma. The present study was carried out to measure and correlate the interdental and interradicular bone loss in patients suffering from periodontitis using radiovisuography (RVG) for the purpose of early furcation diagnosis. Materials and Methods: A total of 50 patients suffering from chronic generalized periodontitis and with furcation involvement in mandibular molars were selected. Under standardized conditions, RVGs were taken and the morphologic measurements defining the furcation areas were recorded and analyzed. Result: Interradicular bone loss of about 0.8 mm or more, was observed in the study subjects only when the bone loss at the interdental area was minimal of 3.7 mm. The correlation between the interradicular and the interdental bone loss was statistically highly significant (T-test, P < 0.001). A stronger correlation was observed in subjects above 40 years of age as compared with the younger subjects. There was not much difference in the degree of correlation between the interradicular and the interdental bone loss when compared in the context of gender. Conclusion: The very first millimeter of interradicular bone loss was seen when the interdental bone loss was around 4 mm. Therefore, to detect the earliest lesions of furcations, the interdental bone loss can be kept as an approximate guide for the comprehensive diagnosis and management of such sites/patients. The current investigation paves the path for future longitudinal studies with larger samples to ascertain these findings. PMID:25210264
NASA Astrophysics Data System (ADS)
Kiram, Johannah Jamalul; Sulaiman, Jumat; Swanto, Suyansah; Din, Wardatul Akmam
2014-07-01
This paper seeks to investigate the relationship between language learning strategies and proficiency in English. Fifty-six pre-university students (22 males, 34 females) of University Malaysia Sabah participated in this study. Oxford's Strategy Inventory for Language Learning (SILL) self-report questionnaire was adopted to identify the students' language learning strategies, whereas their proficiencies were judged based on their Malaysian University English Test (MUET) Results. Pearson's correlation coefficient, Spearman's rank correlation coefficient and the t-test were utilized to make statistical interpretation about the relationship. The knowledge obtained from this study will be helpful for future studies on how to improve the quality of learning and proficiency in English.
Pereira, LutĂ©cia H Mateus; Pineda, Marbin A; Rowe, William H; Fonseca, Libia R; Greene, Mark H; Offit, Kenneth; Ellis, Nathan A; Zhang, Jinghui; Collins, Andrew; Struewing, Jeffery P
2007-01-01
Background We studied linkage disequilibrium (LD) patterns at the BRCA1 locus, a susceptibility gene for breast and ovarian cancer, using a dense set of 114 single nucleotide polymorphisms in 5 population groups. We focused on Ashkenazi Jews in whom there are known founder mutations, to address the question of whether we would have been able to identify the 185delAG mutation in a case-control association study (should one have been done) using anonymous genetic markers. This mutation is present in approximately 1% of the general Ashkenazi population and 4% of Ashkenazi breast cancer cases. We evaluated LD using pairwise and haplotype-based methods, and assessed correlation of SNPs with the founder mutations using Pearson's correlation coefficient. Results BRCA1 is characterized by very high linkage disequilibrium in all populations spanning several hundred kilobases. Overall, haplotype blocks and pair-wise LD bins were highly correlated, with lower LD in African versus non-African populations. The 185delAG and 5382insC founder mutations occur on the two most common haplotypes among Ashkenazim. Because these mutations are rare, even though they are in strong LD with many other SNPs in the region as measured by D-prime, there were no strong associations when assessed by Pearson's correlation coefficient, r (maximum of 0.04 for the 185delAG). Conclusion Since the required sample size is related to the inverse of r, this suggests that it would have been difficult to map BRCA1 in an Ashkenazi case-unrelated control association study using anonymous markers that were linked to the founder mutations. PMID:17916242
Guerrero, Erick G.; Heslin, Kevin C.; Chang, Evelyn; Fenwick, Karissa; Yano, Elizabeth
2014-01-01
This study explored the role of organizational factors in the ability of Veterans Health Administration (VHA) clinics to implement colocated mental health care in primary care settings (PC-MH). The study used data from the VHA Clinical Practice Organizational Survey collected in 2007 from 225 clinic administrators across the United States. Clinic degree of implementation of PC-MH was the dependent variable, whereas independent variables included policies and procedures, organizational context, and leadersâ€™ perceptions of barriers to change. Pearson bivariate correlations and multivariable linear regression were used to test hypotheses. Results show that depression care training for primary care providers and clinicsâ€™ flexibility and participation were both positively correlated with implementation of PC-MH. However, after accounting for other factors, regressions show that only training primary care providers in depression care was marginally associated with degree of implementation of PC-MH (p = 0.051). Given the importance of this topic for implementing integrated care as part of health care reform, these null findings underscore the need to improve theory and testing of more proximal measures of colocation in future work. PMID:25096986
Ngan, E; Lane, C; Ruth, T; Liddle, P
2002-01-01
Objective: Different symptom patterns have been shown to be associated with specific patterns of cerebral metabolic activity in schizophrenia. Treatment with various neuroleptic drugs results in decreased metabolism in frontal cortical regions. The temporal and regional relation between changes in metabolism and symptom improvement after treatment with risperidone was studied in eight previously unmedicated schizophrenic patients. Method: Cerebral metabolic activity was measured using PET before neuroleptic exposure, after the first dose of risperidone, and after 6 weeks of treatment. Pearson correlations were calculated for regions of significant change in metabolism and symptom change. Results: After 6 weeks of treatment significant deactivations were seen in the left lateral cortical frontal region and medial frontal cortex. Significant changes were detectable in the medial frontal region 90 minutes after the first dose of risperidone. Patients with higher baseline activity in the identified medial frontal cluster had higher baseline positive symptom scores and reduction in medial frontal metabolism was correlated with reduction in positive symptom score. Conclusion: The evidence suggests that the reduction in medial-frontal activity after treatment with risperidone is a direct effect of risperidone and not a consequence of symptom improvement. Reduction of medial frontal metabolism may be one of the physiological mechanisms by which risperidone alleviates symptoms of psychosis in schizophrenia. PMID:11784835
Guerrero, Erick G; Heslin, Kevin C; Chang, Evelyn; Fenwick, Karissa; Yano, Elizabeth
2015-07-01
This study explored the role of organizational factors in the ability of Veterans Health Administration (VHA) clinics to implement colocated mental health care in primary care settings (PC-MH). The study used data from the VHA Clinical Practice Organizational Survey collected in 2007 from 225 clinic administrators across the United States. Clinic degree of implementation of PC-MH was the dependent variable, whereas independent variables included policies and procedures, organizational context, and leaders' perceptions of barriers to change. Pearson bivariate correlations and multivariable linear regression were used to test hypotheses. Results show that depression care training for primary care providers and clinics' flexibility and participation were both positively correlated with implementation of PC-MH. However, after accounting for other factors, regressions show that only training primary care providers in depression care was marginally associated with degree of implementation of PC-MH (p = 0.051). Given the importance of this topic for implementing integrated care as part of health care reform, these null findings underscore the need to improve theory and testing of more proximal measures of colocation in future work. PMID:25096986
Correlated Electrons in Reduced Dimensions
Bonesteel, Nicholas E
2015-01-31
This report summarizes the work accomplished under the support of US DOE grant # DE-FG02-97ER45639, "Correlated Electrons in Reduced Dimensions." The underlying hypothesis of the research supported by this grant has been that studying the unique behavior of correlated electrons in reduced dimensions can lead to new ways of understanding how matter can order and how it can potentially be used. The systems under study have included i) fractional quantum Hall matter, which is realized when electrons are confined to two-dimensions and placed in a strong magnetic field at low temperature, ii) one-dimensional chains of spins and exotic quasiparticle excitations of topologically ordered matter, and iii) electrons confined in effectively ``zero-dimensional" semiconductor quantum dots.
Delayed Choice with Correlated Photons
NASA Astrophysics Data System (ADS)
Rössler, O. E.
1988-02-01
A new experiment in the foundations of quantum mechanics is proposed. The existence of correlated photons -first seen by Wheeler -can be taken as a hint to devise a ``double-wing'' delayed choice experiment in Wheeler's sense. A path choice (polarization choice) measurement made on the one side should then block an interference type measurement made on the other side (``distant choice''). A precondition for the combined measurement to work in theory is that the correlated photons used are of the ``prepolarized'' (Selleri) rather than the ``unpolarized'' (Böhm) type. A first EPR experiment involving prepolarized photons was recently performed by Alley and Shih. It may be used as a partial experiment within the proposed experiment.
Correlation of cavitating centrifugal pumps
NASA Astrophysics Data System (ADS)
Zika, V. J.
1984-06-01
The foreknowledge of the minimum NPSH ('net positive suction head') required for a cavitation-free performance of centrifugal pumps is important for a safe and sound operation of these machines. The required NPSH varies from pump to pump, from fluid to fluid, and from temperature to temperature of the pumped fluid. This is known as the thermodynamic effect. The methods currently used for the correlation and analysis of this condition are not always reliable because of the multi-variable nature of the cavitation process. In this paper, two new methods are proposed which lead to more consistent correlations of the required minimum NPSH; thus they can also be used for more dependable predictions of the net positive suction head for any pump, fluid and temperature. The predictions by the two methods do not coincide, but outline a narrow band of probability, within which the actual test points are invariably located.
Bootstrapping N=2 chiral correlators
NASA Astrophysics Data System (ADS)
Lemos, Madalena; Liendo, Pedro
2016-01-01
We apply the numerical bootstrap program to chiral operators in four-dimensional N=2 SCFTs. In the first part of this work we study four-point functions in which all fields have the same conformal dimension. We give special emphasis to bootstrapping a specific theory: the simplest Argyres-Douglas fixed point with no flavor symmetry. In the second part we generalize our setup and consider correlators of fields with unequal dimension. This is an example of a mixed correlator and allows us to probe new regions in the parameter space of N=2 SCFTs. In particular, our results put constraints on relations in the Coulomb branch chiral ring and on the curvature of the Zamolodchikov metric.
Quantum information of cosmological correlations
NASA Astrophysics Data System (ADS)
Lim, Eugene A.
2015-04-01
It has been shown that the primordial perturbations sourced by inflation are driven to classicality by unitary evolution alone. However, their coupling with the environment such as photons and subsequent decoherence renders the cosmological correlations quantum, losing primordial information in the process. We argue that the quantumness of the resulting cosmological correlations is given by quantum discord, which captures nonclassical behavior beyond quantum entanglement. By considering the environment as a quantum channel in which primordial information contained in the perturbations is transmitted to us, we can then ask how much of this information is inaccessible. We show that this amount of information is given by the discord of the joint primordial perturbations-environment system. To illustrate these points, we model the joint system as a mixed bimodal Gaussian state, and show that quantum discord is dependent on the basis which decoherence occurs.
Thermodynamic cost of creating correlations
NASA Astrophysics Data System (ADS)
Huber, Marcus; Perarnau-Llobet, Martí; Hovhannisyan, Karen V.; Skrzypczyk, Paul; Klöckl, Claude; Brunner, Nicolas; Acín, Antonio
2015-06-01
We investigate the fundamental limitations imposed by thermodynamics for creating correlations. Considering a collection of initially uncorrelated thermal quantum systems, we ask how much classical and quantum correlations can be obtained via a cyclic Hamiltonian process. We derive bounds on both the mutual information and entanglement of formation, as a function of the temperature of the systems and the available energy. While for a finite number of systems there is a maximal temperature allowing for the creation of entanglement, we show that genuine multipartite entanglement—the strongest form of entanglement in multipartite systems—can be created at any finite temperature when sufficiently many systems are considered. This approach may find applications, e.g. in quantum information processing, for physical platforms in which thermodynamic considerations cannot be ignored.
A correlated nickelate synaptic transistor
NASA Astrophysics Data System (ADS)
Shi, Jian; Ha, Sieu D.; Zhou, You; Schoofs, Frank; Ramanathan, Shriram
2013-10-01
Inspired by biological neural systems, neuromorphic devices may open up new computing paradigms to explore cognition, learning and limits of parallel computation. Here we report the demonstration of a synaptic transistor with SmNiO3, a correlated electron system with insulator-metal transition temperature at 130°C in bulk form. Non-volatile resistance and synaptic multilevel analogue states are demonstrated by control over composition in ionic liquid-gated devices on silicon platforms. The extent of the resistance modulation can be dramatically controlled by the film microstructure. By simulating the time difference between postneuron and preneuron spikes as the input parameter of a gate bias voltage pulse, synaptic spike-timing-dependent plasticity learning behaviour is realized. The extreme sensitivity of electrical properties to defects in correlated oxides may make them a particularly suitable class of materials to realize artificial biological circuits that can be operated at and above room temperature and seamlessly integrated into conventional electronic circuits.
Semantic Event Correlation Using Ontologies
NASA Astrophysics Data System (ADS)
Moser, Thomas; Roth, Heinz; Rozsnyai, Szabolcs; Mordinyi, Richard; Biffl, Stefan
Complex event processing (CEP) is a software architecture paradigm that aims at low latency, high throughput, and quick adaptability of applications for supporting and improving event-driven business processes. Events sensed in real time are the basic information units on which CEP applications operate and react in self-contained decision cycles based on defined processing logic and rules. Event correlation is necessary to relate events gathered from various sources for detecting patterns and situations of interest in the business context. Unfortunately, event correlation has been limited to syntactically identical attribute values instead of addressing semantically equivalent attribute meanings. Semantic equivalence is particularly relevant if events come from organizations that use different terminologies for common concepts.
Supercritical Angle Fluorescence Correlation Spectroscopy
Ries, Jonas; Ruckstuhl, Thomas; Verdes, Dorinel; Schwille, Petra
2008-01-01
We explore the potential of a supercritical angle (SA) objective for fluorescence correlation spectroscopy (FCS). This novel microscope objective combines tight focusing by an aspheric lens with strong axial confinement of supercritical angle fluorescence collection by a parabolic mirror lens, resulting in a small detection volume. The tiny axial extent of the detection volume features an excellent surface sensitivity, as is demonstrated by diffusion measurements in model membranes with an excess of free dye in solution. All SA-FCS measurements are directly compared to standard confocal FCS, demonstrating a clear advantage of SA-FCS, especially for diffusion measurements in membranes. We present an extensive theoretical framework that allows for accurate and quantitative evaluation of the SA-FCS correlation curves. PMID:17827221
Uranium nitride fuel swelling correlation
NASA Astrophysics Data System (ADS)
Ross, Steven B.; El-Genk, Mohamed S.; Matthews, R. Bruce
1990-02-01
A volumetric swelling correlation for UN fuel with Nb-1% Zr and PWC-11 cladding materials for application to space nuclear power systems was developed as: ?V/ V(%) = 4.7 × 10 -11TaV3.12Bu 0.83?0.5, where Tav is the volume averaged fuel temperature in K, Bu is the fuel burnup (at%), and ? is the as-fabricated fuel density (% of theoretical). This swelling correlation was within ± 25% of the data at burnups in excess of 1.12 at%. However, the scatter of the data at lower burnups resulted in a deviation as high as ± 60%. The reported swelling behavior of the Ta-111 clad fuel pins was consistent with that of the Nb-1% Zr and PWC-11 clad fuel pins. Analysis of W-26% Re clad UN fuel pins was inconclusive because of large scatter and inconsistencies in the data, and reported cladding failures in some tests.
Ultraviolet divergences in cosmological correlations
Weinberg, Steven
2011-03-15
A method is developed for dealing with ultraviolet divergences in calculations of cosmological correlations, which does not depend on dimensional regularization. An extended version of the WKB approximation is used to analyze the divergences in these calculations, and these divergences are controlled by the introduction of Pauli-Villars regulator fields. This approach is illustrated in the theory of a scalar field with arbitrary self-interactions in a fixed flat-space Robertson-Walker metric with arbitrary scale factor a(t). Explicit formulas are given for the counterterms needed to cancel all dependence on the regulator properties, and an explicit prescription is given for calculating finite regulator-independent correlation functions. The possibility of infrared divergences in this theory is briefly considered.
GHAZI MIRSAEID, Seyed Javad; MOTAMEDI, Nadia; RAMEZAN GHORBANI, Nahid
2015-01-01
Background: In this study, the impact of self-citation (Journal and Author) on impact factor of Iranian English Medical journals in two international citation databases, Web of Science (WoS) and Islamic world science citation center (ISC), were compared by citation analysis. Methods: Twelve journals in WoS and 26 journals in ISC databases indexed between the years (2006–2009) were selected and compared. For comparison of self-citation rate in two databases, we used Wilcoxon and Mann-whitney tests. We used Pearson test for correlation of self-citation and IF in WoS, and the Spearman’s correlation coefficient for the ISC database. Covariance analysis was used for comparison of two correlation tests. P. value was 0.05 in all of tests. Results: There was no significant difference between self-citation rates in two databases (P>0.05). Findings also showed no significant difference between the correlation of Journal self-citation and impact factor in two databases (P=0.526) however, there was significant difference between the author’s self-citation and impact factor in these databases (P<0.001). Conclusion: The impact of Author’s self-citation in the Impact Factor of WoS was higher than the ISC. PMID:26587498
NASA Astrophysics Data System (ADS)
Radziszewska-Zielina, El?bieta; Szewczyk, Bart?omiej
2014-11-01
The present paper uses the developed model of the influence of partnering relations on the time, cost, quality and safety of implementation of construction projects. On its basis, a questionnaire has been created and a preliminary survey has been conducted. The paper presents an analysis of correlations between the level of partnering relations in the context of the partnering measures indicated in the model and their influence on the time, cost, quality and safety of implementation of construction projects. The analysis was conducted based on the data collected in 52 construction projects. The values of the Spearman rank correlation coefficient and the Pearson product-moment correlation coefficient have been calculated for the examined relations. The analysis allowed for indicating the measures of partnering whose improvement most often brings benefits with regard to the time, cost, quality and safety of implementation of construction projects. Among the 80 analysed correlations, the ones identified as strong were: 15 relations connected with the time, 8 with the cost, 5 with the quality and 1 with the safety of implementation of construction projects.
NASA Astrophysics Data System (ADS)
Wang, Yuefeng; Chen, Xingwei; Chen, Ying; Liu, Meibing; Gao, Lu
2015-12-01
In order to further investigate the capability of the Standardized Precipitation Index (SPI) to identify flood/drought events, monthly precipitation data from 26 precipitation stations and monthly discharge data from four hydrological stations from 1960 to 2006 in the Minjiang River basin were used to analyze the correlations between multiple time scales of the SPI and river discharge. The SPI series that had a maximum correlation with discharge was chosen to detect flood/drought events in the basin, and the results were compared to historical flood/drought events. The results indicated the following. (1) High Pearson correlations between the SPI and discharge were identified at shorter time scales (1 to 3 months), and the maximum correlation was found on the time scale of 2 months. (2) Five floods among the six largest historical flood events in the Minjiang River basin were identified with the 2-month SPI, but the SPI does have shortcomings in identifying more general floods. The SPI also identified major drought events that were consistent with historical data. This demonstrates that the 2-month SPI is an effective indicator for the identification of major flood/drought events in the Minjiang River basin.
Miller, J M; Ashton-Miller, J A; Carchidi, L T; DeLancey, J O
1999-03-01
This study examined the association between the measured amount of urine lost during a standardized series of coughs in clinic (paper towel test) and questionnaire estimates of stress-related urine loss in 51 older women with mild to moderate urinary incontinence. It also examined the relationship between these questionnaire estimates and a 6-day urinary diary self-report of incontinence frequency and voiding episodes. Pearson's correlation coefficient and percent agreement were used to analyze the relationship between the variables. No significant correlations were found between the paper towel test results and questionnaire items reporting volume of urine loss. The relationship between urinary diary results and questionnaire items regarding the number of incontinence occurrences was weak but significant (r = 0.33, p = 0.045), with agreement in 53% of cases. Agreement was achieved in 68% of cases for number of voids per day recorded by urinary diary and reported by questionnaire (r = 0.65, p = 0.000). This study has quantified a weak correlation between objective and subjective measures of urine loss. These weak correlations could arise from either methodologic limitations in quantifying incontinence or the degree to which differences arise because different phenomena are being measured. PMID:10100129
Salaffi, Fausto; Carotti, Marina; Bosello, Silvia; Bichisecchi, Elisabetta; Giuseppetti, Gianmarco; Ferraccioli, Gianfranco
2015-01-01
Objective. To evaluate the performance of a computerized-aided method (CaM) for quantification of interstitial lung disease (ILD) in patients with systemic sclerosis and to determine its correlation with the conventional visual reader-based score (CoVR) and the pulmonary function tests (PFTs). Methods. Seventy-nine patients were enrolled. All patients underwent chest high resolution computed tomography (HRCT) scored by two radiologists adopting the CoVR. All HRCT images were then analysed by a CaM using a DICOM software. The relationships among the lung segmentation analysis, the readers, and the PFTs results were calculated using linear regression analysis and Pearson's correlation. Receiver operating curve analysis was performed for determination of CaM extent threshold. Results. A strong correlation between CaM and CoVR was observed (P < 0.0001). The CaM showed a significant negative correlation with forced vital capacity (FVC) (P < 0.0001) and the single breath carbon monoxide diffusing capacity of the lung (DLco) (P < 0.0001). A CaM optimal extent threshold of 20% represented the best compromise between sensitivity (75.6%) and specificity (97.4%). Conclusions. CaM quantification of SSc-ILD can be useful in the assessment of extent of lung disease and may provide reliable tool in daily clinical practice and clinical trials. PMID:25629053
Correlated Temporal and Spectral Variability
NASA Technical Reports Server (NTRS)
Swank, Jean H.
2007-01-01
The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.
Correlative fluorescence and electron microscopy.
Schirra, Randall T; Zhang, Peijun
2014-01-01
Correlative fluorescence and electron microscopy (CFEM) is a multimodal technique that combines dynamic and localization information from fluorescence methods with ultrastructural data from electron microscopy, to give new information about how cellular components change relative to the spatiotemporal dynamics within their environment. In this review, we will discuss some of the basic techniques and tools of the trade for utilizing this attractive research method, which is becoming a very powerful tool for biology labs. The information obtained from correlative methods has proven to be invaluable in creating consensus between the two types of microscopy, extending the capability of each, and cutting the time and expense associated with using each method separately for comparative analysis. The realization of the advantages of these methods in cell biology has led to rapid improvement in the protocols and has ushered in a new generation of instruments to reach the next level of correlation-integration. Curr. Protoc. Cytom. 70:12.36.1-12.36.10. © 2014 by John Wiley & Sons, Inc. PMID:25271959
Alzheimer's disease: a correlative study.
Neary, D; Snowden, J S; Mann, D M; Bowen, D M; Sims, N R; Northen, B; Yates, P O; Davison, A N
1986-01-01
In a study of 17 patients with histologically proven Alzheimer's disease the relationship between psychological, pathological and chemical measures of disorder was examined. Severity of dementia, determined by mental test performance, correlated highly with pathological change in large cortical neurons (cell loss and reduction in nuclear and nucleolar volume and cytoplasmic RNA content), to a lesser extent with cortical senile plaque and neurofibrillary tangle frequency and reduction in acetylcholine (ACh) synthesis, and not with reduction in choline acetyltransferase (CAT) activity. A strongly significant relationship was demonstrated between cell loss and reductions in nuclear and nucleolar volume and cytoplasmic RNA content. Reduction in CAT activity and senile plaque frequency were significantly correlated, thereby linking changes in the sub-cortical projection system of the nucleus basalis with the cortical pathology. The pattern of correlations suggests that the dementia of Alzheimer's disease is largely a reflection of the state of large cortical neurons, and it is argued that abnormalities in the latter may not be directly related to primary loss of cholinergic neurons in the subcortex. PMID:2420941
Blalock, Eric M; Chen, Kuey-Chu; Sharrow, Keith; Herman, James P; Porter, Nada M; Foster, Thomas C; Landfield, Philip W
2003-05-01
Gene expression microarrays provide a powerful new tool for studying complex processes such as brain aging. However, inferences from microarray data are often hindered by multiple comparisons, small sample sizes, and uncertain relationships to functional endpoints. Here we sought gene expression correlates of aging-dependent cognitive decline, using statistical profiling of gene microarrays in well powered groups of young, mid-aged, and aged rats (n = 10 per group). Animals were trained on two memory tasks, and the hippocampal CA1 region of each was analyzed on an individual microarray (one chip per animal). Aging- and cognition-related genes were identified by testing each gene by ANOVA (for aging effects) and then by Pearson's test (correlating expression with memory). Genes identified by this algorithm were associated with several phenomena known to be aging-dependent, including inflammation, oxidative stress, altered protein processing, and decreased mitochondrial function, but also with multiple processes not previously linked to functional brain aging. These novel processes included downregulated early response signaling, biosynthesis and activity-regulated synaptogenesis, and upregulated myelin turnover, cholesterol synthesis, lipid and monoamine metabolism, iron utilization, structural reorganization, and intracellular Ca2+ release pathways. Multiple transcriptional regulators and cytokines also were identified. Although most gene expression changes began by mid-life, cognition was not clearly impaired until late life. Collectively, these results suggest a new integrative model of brain aging in which genomic alterations in early adulthood initiate interacting cascades of decreased signaling and synaptic plasticity in neurons, extracellular changes, and increased myelin turnover-fueled inflammation in glia that cumulatively induce aging-related cognitive impairment. PMID:12736351
Merolla, Giovanni; Campi, Fabrizio; Paladini, Paolo; Lollino, Nicola; Fauci, Francesco; Porcellini, Giuseppe
2009-04-01
Glenoid component loosening is the weak point in the failure of total shoulder arthroplasty (TSA). In this study we analyse the radiographic risk factors observed on 86 cemented polyethylene glenoid components and their relationship with clinical signs at a mean follow-up of 5.8 years. Clinical assessment included Simple Shoulder Test (SST) and Constant-Murley score. Radiograms were taken to detect periprosthetic radiolucency, tilt, medial displacement and polyethylene thinning. Pearson's correlation coefficient and Spearman's rank correlation coefficient were calculated for statistical analysis. In 61 patients (71%) lucent lines were less than 2 mm wide (grade 2) and in 6 cases (7%) they were >or=2 mm wide (grade 3 and 4). Thinning of the polyethylene was found in 11 cases (13%), glenoid tilt in 6 cases (7%) and medial migration of the component in 5 cases (6%). Complete glenoid prosthetic loosening was found in 3 cases (3.5%) associated with polyethylene wear and glenoid bone loss. The Constant-Murley score associated with radiolucency grade 3 and 4 was less than 45% (38.39 +/- 8.9) (p < 0.05), while a score less than 56% (30.72 +/- 8.7) was found in patients with glenoid tilt and medial migration (p < 0.01). The mean SST score was 4.8 +/- 2.8 in case of glenoid tilt and migration of the component (p < 0.01). Removal of the glenoid component and conversion to hemiarthroplasty or reverse prostheses is suggested in painful glenoid loosening. An exhaustive analysis of radiograms is essential to detect early and late complications or risk factors of glenoid loosening. PMID:19711167
[Leptin in patients with polycystic ovary syndrome. Direct correlation with insulin resistance].
Calvar, Cecilia E; Intebi, Alberto D; Bengolea, Sonia V; Hermes, Ricardo; Spinedi, Eduardo
2003-01-01
Up to now it is unclear whether there is a relationship between insulin resistance and circulating leptin levels (LEP) in women with polycystic ovary syndrome (PCOS). To assess the role of LEP in PCOS and to clarify the relationship between plasma LEP levels and insulin resistance (IR) in PCOS patients, we studied 49 women with PCOS and 14 normal premenopausal women. All subjects were evaluated by a 2 hours, 75 g, oral glucose tolerance test. Fasting plasma LEP, insulin, glucose, insulin sensitivity indexes and LEP:body mass index (BMI) were determined. Results were analyzed by ANOVA and the Pearson's correlation test when appropriate. The results indicate that: 1) no differences were found in basal plasma LEP levels (ng/ml) between normal (17.6 +/- 4.9) and PCOS (21.9 +/- 2.8) women; 2) in PCOS patients, a significant (P < 0.01) correlation between plasma LEP levels and BMI and insulin sensitivity indexes were found; and 3) seventeen PCOS patients were insulin resistant (IR) and showed higher basal plasma LEP levels (32.8 +/- 4.3, P < 0.01) and LEP:BMI (0.95 +/- 0.09, P < 0.05) than non insulin resistant (non IR) PCOS subjects (16.2 +/- 3.2 and 0.61 +/- 0.08, respectively). Our results suggest that PCOS seems to be associated with normoleptinemia, however, if IR are analyzed separately from non IR PCOS patients, there is a clear relationship between IR PCOS and hyperleptinemia, regardless of the BMI. The present study strongly supports bi-directional relationship between fat and carbohydrate metabolisms under a very particular physiopathological condition (PCOS). PMID:14719312
A Correlation Study of Student Attitudes Toward Science in a Southern State High School
NASA Astrophysics Data System (ADS)
Barco-Southall, Crystal
The purpose of this correlational research study was to examine the attitudes toward science of students in Grades 11 and 12 and to investigate if there were differences resulting from gender, grade level, ethnicity, and the level of the curriculum received in average or advanced placement (AP) honors science. The participants of this study consisted of 50 randomly selected male and female high school students who were enrolled in AP and average science classes in an urban Southern state high school. The study used the Test of Science Related Attitudes (TOSRA) instrument to measure students' attitudes toward science in seven categories including (a) Social Implications of Science, (b) Normality of Scientists, (c) Attitude Toward Scientific Inquiry, (d) Adoption of Scientific Attitudes, (e) Enjoyment of Science Lessons, (f) Leisure Interest in Science, and (g) Career Interest in Science. The quantitative component of the study allowed the researcher to determine whether there were gender differences in attitudes toward science based on the seven subscales and measuring different aspects of science attitudes. Statistical treatment of the TOSRA survey involved the use of descriptive statistics, Pearson correlation, and multiple and linear regression. Findings did not reveal significant gender differences on the total attitude scores although there were differences on several of the subscales. In addition, there were no significant differences in the mean attitude scores for grade level. However, the study did reveal differences in ethnicity and attitudes toward science. With regard to ethnicity, scores for Native Americans and Whites were higher than scores for Asians, African Americans, and Hispanics indicating that Native Americans and White students showed a more positive attitude toward science. Regarding the level of curriculum received by students who were exposed to advanced level science courses showed more positive attitudes toward science than those students who were enrolled in average science classes.
Treit, S; Chen, Z; Rasmussen, C; Beaulieu, C
2014-09-12
Inhibitory control and cognitive flexibility are two key executive functions that develop in childhood and adolescence, increasing one's capacity to respond dynamically to changing external demands and refrain from impulsive behaviors. These gains evolve in concert with significant brain development. Magnetic resonance imaging studies have identified numerous frontal and cingulate cortical areas associated with performance on inhibition tasks, but less is known about the involvement of the underlying anatomical connectivity, namely white matter. Here we used diffusion tensor imaging (DTI) to examine correlations between a DTI-derived parameter, fractional anisotropy (FA) of white matter, and performance on the NEPSY-II Inhibition test (Naming, Inhibition and Switching conditions) in 49 healthy children aged 5-16years (20 females; 29 males). First, whole brain voxel-based analysis revealed several clusters in the frontal projections of the corpus callosum, where higher FA was associated with worse inhibitory performance, as well as several clusters in posterior brain regions and one in the brainstem where higher FA was associated with better cognitive flexibility (in the Switching task), suggesting a dichotomous relationship between FA and these two aspects of cognitive control. Tractography through these clusters identified several white matter tracts, which were then manual traced in native space. Pearson's correlations confirmed associations between higher FA of frontal projections of the corpus callosum with poorer inhibitory performance (independent of age), though associations with Switching were not significant. Post-hoc evaluation suggested that FA of orbital and anterior frontal projections of the corpus callosum also mediated performance differences across conditions, which may reflect differences in self-monitoring or strategy use. These findings suggest a link between the development of inhibition and cognitive control with that of the underlying white matter, and may help to identify deviations of neurobiology in adolescent psychopathology. PMID:24355493
Enamel lesion parameter correlations between polychromatic micro-CT and TMR.
Hamba, H; Nikaido, T; Sadr, A; Nakashima, S; Tagami, J
2012-06-01
Transverse microradiography (TMR) is considered as the gold standard technique for the evaluation of enamel lesions. Micro-computed tomography (ÂµCT) has the advantage of non-destructive measurements, but the beam-hardening effect with polychromatic x-rays is a major drawback. To date, no study has validated ÂµCT against TMR. The objective of this study was to validate ÂµCT measurements of enamel lesions under various x-ray conditions and software beam-hardening correction (BHC) against TMR. Human molars with natural white-spot lesions were scanned for 5 min by ÂµCT at 100 kV in different conditions: 50 ÂµA (0.5-mm Al filter), 165 ÂµA (0.5-mm Al/0.3-mm Cu), and 200 ÂµA (0.5-mm Al/0.4-mm Cu), with or without BHC. Grayscale values were converted into mineral density values using phantoms. Thin sections at the same positions were then prepared for TMR. Lesion depth (LD; Âµm) and mineral loss (Î”Z; vol%Âµm) were compared between ÂµCT and TMR by Pearson's correlations. ÂµCT measurements correlated well with TMR under all conditions (p < 0.001, r > 0.86 for LD and Î”Z), except for 0.5-mm Al without BHC (p > 0.05). Even without BHC, combined Al/Cu filters successfully reduced the beam-hardening effect. ÂµCT can be used as a non-destructive alternative to TMR with comparable parameters for the study of enamel lesions. PMID:22476867
Li, Yan; Zhang, Liying; Kallakuri, Srinivasu; Cohen, Abigail; Cavanaugh, John M
2015-12-15
A modified Marmarou impact acceleration model was used to help screen biomarkers to assess brain injury severity. Anesthetized male Sprague-Dawley rats were subjected to a closed head injury from 1.25, 1.75 and 2.25m drop heights. Linear and angular responses of the head were measured in vivo. 24h after impact, cerebrospinal fluid (CSF) and serum were collected. CSF and serum levels of phosphorylated neurofilament heavy (pNF-H), glial fibrillary acidic protein (GFAP), interleukin 6 (IL-6), and amyloid beta (A?) 1-42 were assessed by enzyme-linked immunosorbent assay (ELISA). Compared to controls, significantly higher CSF and serum pNF-H levels were observed in all impact groups, except between 1.25m and control in serum. Furthermore, CSF and serum pNF-H levels were significantly different between the impact groups. For GFAP, both CSF and serum levels were significantly higher at 2.25m compared to 1.75m, 1.25m and controls. There was no significant difference in CSF and serum GFAP levels between 1.75m and 1.25m, although both groups were significantly higher than control. TBI rats also showed significantly higher levels of IL-6 versus control in both CSF and serum, but no significant difference was observed between each impact group. Levels of A? were not significantly different between groups. Pearson's correlation analysis showed pNF-H and GFAP levels in CSF and serum had positive correlation with power (rate of impact energy), followed by average linear acceleration and surface righting (p<0.01), which were good predictors for traumatic axonal injury according to histologic assessment in our previous study, suggesting that they are directly related to the injury mechanism. The model used in this study showed a unique ability in elucidating the relationship between biomarker levels and severity of the mechanical trauma to the brain. PMID:26671128
NASA Astrophysics Data System (ADS)
Reddick, Wilburn E.; Glass, John O.; Shan, Zuyao Y.; Wu, Shengjie; Helton, Susan; Mulhern, Raymond K.
2005-04-01
Due to the inherent risk of central nervous system (CNS) dissemination, children treated for either acute lymphoblastic leukemia (ALL) or malignant brain tumors (BT) receive aggressive CNS therapy. The primary objective of this study was to confirm a previously observed association between reduced volumes of normal-appearing white matter (NAWM) and intellectual and attentional deficits in survivors. A combined MR imaging set consisting of T1, T2, and PD images were collected for 221 children (110 BT; 112 ALL). MR imaging sets were segmented with a hybrid neural network algorithm and volumetric measurements were calculated for five slices centered on the basal ganglia. Summary measures of Overall Index, Omissions, d" (attentiveness), and beta (risk-taking) were derived from the computer-administered Conners" Continuous Performance Test (CPT). Age-corrected estimates of Full-Scale IQ (FSIQ) were also obtained. Pearson correlation analyses were performed between each neurocognitive measure and the volume of NAWM. The correlation between FSIQ and NAWM failed to reach statistical significance for the BT group but was highly significant for the more homogeneous ALL group. Larger Omission rates, decreased attentiveness and more risk taking were significantly associated with lower NAWM volumes in both groups of survivors. Long-term survivors are at increased risk for cognitive delays or deficits, which oftentimes impair future academic performance, employment, and quality of life. These long-term adverse effects of treatment appear to be due to a diminished ability to acquire new information and may be secondary to deficits in attention, which is thought to be supported by interhemispheric and intrahemispheric white matter tracts.
Fromonot, J; Deharo, P; Bruzzese, L; Cuisset, T; Quilici, J; Bonatti, S; Fenouillet, E; Mottola, G; Ruf, J; Guieu, R
2016-03-01
The role of hyperhomocysteinemia in coronary artery disease (CAD) patients remains unclear. The present study evaluated the relationship between homocysteine (HCys), adenosine plasma concentration (APC), plasma uric acid, and CAD severity evaluated using the SYNTAX score. We also evaluated in vitro the influence of adenosine on HCys production by hepatoma cultured cells (HuH7). Seventy-eight patients (mean age ± SD: 66.3 ± 11.3; mean SYNTAX score: 19.9 ± 12.3) and 30 healthy subjects (mean age: 61 ± 13) were included. We incubated HuH7 cells with increasing concentrations of adenosine and addressed the effect on HCys level in cell culture supernatant. Patients vs. controls had higher APC (0.82 ± 0.5 ?mol/L vs 0.53 ± 0.14 ?mol/L; p < 0.01), HCys (15 ± 7.6 ?mol/L vs 6.8 ± 3 ?mol/L, p < 0.0001), and uric acid (242.6 ± 97 vs 202 ± 59, p < 0.05) levels. APC was correlated with HCys and uric acid concentrations in patients (Pearson's R = 0.65 and 0.52; p < 0.0001, respectively). The SYNTAX score was correlated with HCys concentration. Adenosine induced a time- and dose-dependent increase in HCys in cell culture. Our data suggest that high APC is associated with HCys and uric acid concentrations in CAD patients. Whether the increased APC participates in atherosclerosis or, conversely, is part of a protective regulation process needs further investigations. PMID:26762617
Correlation Between Cephalometric Measures and End-of-Treatment Facial Attractiveness.
Yu, Xiao-Nan; Bai, Ding; Feng, Xue; Liu, Yue-Hua; Chen, Wen-Jing; Li, Song; Han, Guang-Li; Jiang, Ruo-Ping; Xu, Tian-Min
2016-03-01
Sixty-nine experienced Chinese orthodontists evaluated 108 Chinese patients' facial attractiveness from set of photographs (frontal, lateral, and frontal smiling photos) taken at the end of orthodontic treatment. These 108 patients, which contained an equal number of patients with Class I, II, and III malocclusion, were randomly selected from 6 orthodontic treatment centers throughout China. Spearman rank-order correlation coefficients (rs) analyses were performed to examine agreement in ranking between all judge pairs. Pearson correlation and multivariate regression were performed to examine the correlation between cephalometric measures and end-of-treatment Photo Attractiveness Rank.96.68% judge pairs showed moderate correlated (+0.4â€Šâ‰¤â€Šrsâ€Š<â€Š+0.7) subjective rankings. Cephalometric measures significantly correlated with end-of-treatment Photo Attractiveness Rank included interincisal angle (râ€Š=â€Š0.330, Pâ€Š<â€Š0.05), L1/MPÂ° (râ€Š=â€Š0.386, Pâ€Š<â€Š0.05), L1-NBmm (râ€Š=â€Š0.451, Pâ€Š<â€Š0.01), L1/NBÂ° (râ€Š=â€Š0.374, Pâ€Š<â€Š0.05), and profile angle (râ€Š=â€Š0.353, Pâ€Š<â€Š0.05) in Class I patients with an explained variance of 32.8%, and ANB angle (râ€Š=â€Š0.432, Pâ€Š<â€Š0.01), angle of convexity (râ€Š=â€Š0.448, Pâ€Š<â€Š0.01), profile angle (râ€Š=â€Š0.488, Pâ€Š<â€Š0.01), Li to E-line (râ€Š=â€Š0.374, Pâ€Š<â€Š0.05), Li to B-line (râ€Š=â€Š0.543, Pâ€Š<â€Š0.01), and Z angle (râ€Š=â€Š0.543, Pâ€Š<â€Š0.01) in Class II patient with an explained variance of 43.3%.There was less association than expected between objective measurements on the lateral cephalograms and clinicians' rankings of facial attractiveness on clinical photography in Chinese patients. Straight-stand lower incisor was desired for facial attractiveness of Class I malocclusion; and sagittal relationship and lip prominence influence the esthetics of Class II malocclusion in Chinese population. PMID:26872281
Bae, Won C.; Chen, Peter C.; Chung, Christine B.; Masuda, Koichi; Dâ€™Lima, Darryl; Du, Jiang
2012-01-01
In this study we describe the use of ultrashort echo time (UTE) magnetic resonance imaging (MRI) to evaluate short and long T2* components as well as the water content of cortical bone. Fourteen human cadaveric distal femur and proximal tibia were sectioned to produce 44 rectangular slabs of cortical bone for quantitative UTE MR imaging, micro computed tomography (ÎĽCT), and biomechanical testing. A two-dimensional (2D) UTE pulse sequence with a minimal nominal TE of 8 ÎĽs was used together with bi-component analysis to quantify the bound and free water in cortical bone using a clinical 3T scanner. Total water concentration was measured using a 3D UTE sequence together with a reference water phantom. UTE MR measures of water content (total, free and bound), T2* (short and long), and short and long T2* fractions were compared to porosity assessed with ÎĽCT, as well as elastic (modulus, yield stress and strain) and failure (ultimate stress, failure strain and energy) properties, using Pearson correlation. Porosity significantly correlated positively with total (R2=0.23; P<0.01) and free (R2=0.31; P<0.001) water content as well as long T2* fraction (R2=0.25; P<0.001), and negatively with short T2* fraction and short T2* (R2=0.24; P<0.01). Failure strain significantly correlated positively with short T2* (R2=0.29; P<0.001), ultimate stress significantly correlated negatively with total (R2=0.25; P<0.001) and bound (R2=0.22; P<0.01) water content, and failure energy significantly correlated positively with both short (R2=0.30; P<0.001) and long (R2=0.17; P<0.01) T2* values. These results suggest that UTE MR measures are sensitive to the structure and failure properties of human cortical bone, and may provide a novel way of evaluating cortical bone quality. PMID:22190232
Fischbach, H; Hoffmeister, H M; Hoffmeister, H E; Apitz, J; Schmidt, C
1982-01-01
To improve the evaluation of grades of pulmonary vascular lesions in congenital heart malformations, we studied the extent to which there is a measurable relationship between pressure conditions in the pulmonary circulation and the area of the media in small and medium-sized pulmonary arteries, and the possibility of a correlation between the subjective evaluation of grades of hypertensive pulmonary vascular lesions according to Heath and Edwards (1958). Material and methods. The lungs in 68 children (mean age, 22.7 months) with congenital malformations of the heart or great vessels resulting in pulmonary hypertension were examined. The lungs were fixed in a 4% formalin solution passed via the trachea under a constant filling pressure of 150 cm H2O. Peripheral as well as central tissue was removed from all lobes of the lungs; the specimens were stained with Elastica-van Gieson. The extent of hypertensive pulmonary vasculopathy was staged, without knowledge of the pressure conditions, according to the grading system developed by Heath and Edwards. The diameter and the area of all muscular arteries with diameters smaller or larger than 100 micron were measured using a semiautomatic measurement device for quantitative morphometric analysis (MOP/AM 01). Cardiac catheter values were available for all cases. The quotient of systolic pressures in the pulmonary artery and the aorta was taken as the measure of hemodynamic conditions in the pulmonary circulation. The Pearson-Bravais correlation coefficient (r) was computed from the respective area quotient and the corresponding pressure values. In addition, the coefficient of determination (r2) and regression functions were determined. Results. A linear correlation (r = 0.70) exists between the pressure quotient (Psyst. pulm. art./ Psyst. aorta) and the vessel area quotient (media area/total area). The correlation is expressed by the following functions: x = 1.89 y - 0.08 y = 0.26 x + 0.24 Using the Heath and Edwards grading, the following frequencies were obtained: Grade 0: 21, Grade I: 7, Grade II: 16, Grade III: 15, Grade IV: 6, and 3 children were undeterminable. No relationship exists between the grades and certain heart malformations. In spite of the fact that hypertensive vasculopathy becomes progressively more severe as the child grows older, we found four cases of Grade IV in children under the age of one. On the whole, a comparison of the measured area quotients and the Heath and Edwards grading showed a good correlation. Although we considered only pressure quotients and no other hemodynamic parameters, conclusions can be drawn about the operability of congenital heart malformations based on these findings. Using measured pressure values, the morphologic state of the pulmonary arteries can be approximately evaluated. PMID:7122326
PREFACE: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Saxena, Siddharth S.; Littlewood, P. B.
2012-07-01
This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to goâ€”note that this progress is founded on investments and studies in the fundamentals of condensed matter physics from more than 50 years ago. Nevertheless, the defining challenges for the 21st century will lie in the discovery in science, and deployment through engineering, of technologies that can deliver the scale needed to have an impact on the sustainability agenda. Thus the big developments in nanotechnology may lie not in the pursuit of yet smaller transistors, but in the design of new structures that can revolutionise the performance of solar cells, batteries, fuel cells, light-weight structural materials, refrigeration, water purification, etc. The science presented in the papers of this special section also highlights the underlying interest in energy-dense materials, which make use of 'small' electrons packed to the highest possible density. These are by definition 'strongly correlated'. For example: good photovoltaics must be efficient optical absorbers, which means that photons will generate tightly bound electron-hole pairs (excitons) that must then be ionised at a heterointerface and transported to contacts; efficient solid state refrigeration depends on substantial entropy changes in a unit cell, with large local electrical or magnetic moments; efficient lighting is in a real sense the inverse of photovoltaics; the limit of an efficient battery is a supercapacitor employing mixed valent ions; fuel cells and solar to fuel conversion require us to understand electrochemistry on the scale of a single atom; and we already know that the only prospect for effective high temperature superconductivity involves strongly correlated materials. Even novel IT technologies are now seen to have value not just for novel function but also for efficiency. While strongly correlated electron systems continue to excite researchers and the public alike due to the fundamental science issues involved, it seems increasingly likely that support for the science will be leveraged by its impact on energy and sustainability. Strongly correlated electron systems contents Strongly correlated electron systemsSiddharth S Saxena and P B Littlewood Magnetism, f-electron localization and superconductivity in 122-type heavy-fermion metalsF Steglich, J Arndt, O Stockert, S Friedemann, M Brando, C Klingner, C Krellner, C Geibel, S Wirth, S Kirchner and Q Si High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopyN L Wang, W Z Hu, Z G Chen, R H Yuan, G Li, G F Chen and T Xiang Structural investigations on YbRh2Si2: from the atomic to the macroscopic length scaleS Wirth, S Ernst, R Cardoso-Gil, H Borrmann, S Seiro, C Krellner, C Geibel, S Kirchner, U Burkhardt, Y Grin and F Steglich Confinement of chiral magnetic modulations in the precursor region of FeGeH Wilhelm, M Baenitz, M Schmidt, C Naylor, R Lortz, U K RĂ¶Ăźler, A A Leonov and A N Bogdanov Antiferromagnetism in metals: from the cuprate superconductors to the heavy fermion materialsSubir Sachdev, Max A Metlitski and Matthias Punk Superconducting gap structure of the 115s revisitedF Ronning, J-X Zhu, Tanmoy Das, M J Graf, R C Albers, H B Rhee and W E Pickett Nonmagnetic ground states and phase transitions in the caged compounds PrT2Zn20 (T = Ru, Rh and Ir)T Onimaru, K T Matsumoto, N Nagasawa, Y F Inoue, K Umeo, R Tamura, K Nishimoto, S Kittaka, T Sakakibara and T Takabatake New universality class of quantum criticality in Ce- and Yb-based heavy fermionsShinji Watanabe and Kazumasa Miyake
NASA Technical Reports Server (NTRS)
Johnson, R. A.; Wehrly, T.
1976-01-01
Population models for dependence between two angular measurements and for dependence between an angular and a linear observation are proposed. The method of canonical correlations first leads to new population and sample measures of dependence in this latter situation. An example relating wind direction to the level of a pollutant is given. Next, applied to pairs of angular measurements, the method yields previously proposed sample measures in some special cases and a new sample measure in general.
?B-crystallin expression is correlated with phospho-ERK1/2 expression in human breast cancer.
van de Schootbrugge, Chantal; van Asten, Freekje; Nagtegaal, Iris D; Versleijen-Jonkers, Yvonne M; van Laarhoven, Hanneke W M; Roeffen, Melissa H; Sweep, Fred C G J; Bussink, Johan; Kaanders, Johannes H A M; Pruijn, Ger J M; Boelens, Wilbert C; Span, Paul N
2013-01-01
?B-crystallin is regarded as a biomarker for triple-negative and/or basal-like breast cancer. In normal breast cells, overexpression of ?B-crystallin leads to neoplastic-like changes, which likely relate to enhanced expression of phosphorylated ERK1/2 (pERK1/2). In this study, we investigated whether ?B-crystallin expression is correlated to pERK1/2 expression in breast cancer. In a balanced tissue microarray the expression of ?B-crystallin and pERK1/2 kinase were determined immunohistochemically, together with the triple-negativity and basal-like markers CK5/6 and SMA and the signaling molecules pAKT, pmTOR, EGFR, and IGF-1R. ?B-crystallin expression significantly correlated with triple negativity and basal-like markers CK5/6 and SMA (Pearson Chi-square test p=0.004, p=0.001, and p<0.001, respectively). A significant correlation was also observed with pERK1/2 expression (p=0.002). siRNA-mediated knockdown of ?B-crystallin in the triple-negative breast cell line MDA-MB468 did not show an effect on pERK1/2 expression levels, indicating that lowering the level of ?B-crystallin does not reduce pERK1/2 expression. Our results confirm that ?B-crystallin can be used as a biomarker for triple-negative and/or basal-like breast cancer. The expression of ?B-crystallin correlates with pERK1/2 expression in breast cancer tissue suggesting that therapies targeting ?B-crystallin might be considered for treatment of triple-negative or basal-like breast cancer. PMID:23722303
Su, Di; Zhang, Chuan-ling; Gao, Ying-chun; Liu, Xiao-ying; Li, Cai-ping; Huangfu, Jian; Xiao, Rui
2015-01-01
Background The aim of this work was to study the Fabp4 and Pten gene expression and correlation in the liver, muscle, and adipose tissues of type 2 diabetes mellitus (T2DM) rats. Material/Methods Male Wistar rats (8 weeks old) were randomly divided into 2 groups (n=12/group): a control group fed a normal diet for 8 weeks and an experimental group fed a high-fat, high-sugar diet for 8 weeks and that received 25 mg/kg streptozotocin by intraperitoneal injection to induce T2DM. The random blood glucose, fasting blood glucose, and fasting insulin levels were measured. The expression of Pten and Fabp4 in the liver, muscle, and epididymal adipose tissues was estimated by real-time quantitative PCR. Pearson correlation coefficient analysis was used to investigate the expression correlation between Pten and Fabp4 in T2DM rats. Results The gene expressions of Pten and Fabp4 in the liver, muscle, and adipose tissues of T2DM rats were all significantly higher than those in the control group (P<0.05). Pten was highly expressed in the muscles and Fabp4 was highly expressed in muscle and adipose tissues. Furthermore, expressions of Fabp4 and Pten in the muscle and adipose tissues of T2DM rats were positively correlated (P<0.05), but not in the liver. Conclusions The increased expression of PTEN and FABP4 in the adipose and muscles of T2DM rats may play an important role in the insulin resistance of T2DM. However, the mechanism by which these 2 genes function in T2DM needs further study. PMID:26591002
Ashraf, Alireza; Farahangiz, Siamak; Pakniat Jahromi, Bita; Setayeshpour, Nazanin; Nasseri, Ali
2014-01-01
Study Design A cross-sectional study. Purpose To describe the correlation between lumbar lordosis angle and functional status of patients with chronic mechanical low back pain (CMLBP). Overview of Literature There are different and conflicting opinions regarding the relationship between the degree of lumbar lordosis and functional status of patients with low back pain. Nonetheless, the severity of lordosis is still one of the routine physical exams considered in rehabilitation clinics. Methods The degree of lumbar lordosis of 150 patients with CMLBP was measured by means of Cobb's method using sagittal standing spinal radiographs. Subjects with probable secondary causes of low back pain (trauma, congenital anomaly, spinal infection, rheumatologic problems and history of spinal surgery) were excluded. Besides recording demographic data, their score of functional disability was estimated using Oswestry Disability Questionnaire, one of the most useful and reliable questionnaires. Comparison between these data was made regarding different age and gender groups. Results In this study, 119 subjects were female and 31 male, with an age range of 19-85 years. The average degree of lumbar lordosis was 44.69±11.43 and that of Oswestry disability index (ODI) 30.52%. Although we found a significant direct relationship between age and degree of lumbar lordosis (Pearson's correlation coefficient, p=0.016, r=0.197), while insignificant correlation was seen between the degree of lumbar lordosis and ODI (p=0.129). Conclusions There was no significant correlation between the degree of lumbar lordosis and the score of functional disability with regards to different age groups and gender. PMID:25346808
Variable Selection through Correlation Sifting
NASA Astrophysics Data System (ADS)
Huang, Jim C.; Jojic, Nebojsa
Many applications of computational biology require a variable selection procedure to sift through a large number of input variables and select some smaller number that influence a target variable of interest. For example, in virology, only some small number of viral protein fragments influence the nature of the immune response during viral infection. Due to the large number of variables to be considered, a brute-force search for the subset of variables is in general intractable. To approximate this, methods based on â„“1-regularized linear regression have been proposed and have been found to be particularly successful. It is well understood however that such methods fail to choose the correct subset of variables if these are highly correlated with other "decoy" variables. We present a method for sifting through sets of highly correlated variables which leads to higher accuracy in selecting the correct variables. The main innovation is a filtering step that reduces correlations among variables to be selected, making the â„“1-regularization effective for datasets on which many methods for variable selection fail. The filtering step changes both the values of the predictor variables and output values by projections onto components obtained through a computationally-inexpensive principal components analysis. In this paper we demonstrate the usefulness of our method on synthetic datasets and on novel applications in virology. These include HIV viral load analysis based on patients' HIV sequences and immune types, as well as the analysis of seasonal variation in influenza death rates based on the regions of the influenza genome that undergo diversifying selection in the previous season.
Correlation-induced spectral changes
NASA Astrophysics Data System (ADS)
Wolf, Emil; James, Daniel F. V.
1996-06-01
This paper presents a review of research, both theoretical and experimental, concerning the influence of coherence properties of fluctuating light sources and of correlation properties of scattering media on the spectra of radiated and scattered fields. Much of this research followed a discovery made in 1986, that the spectrum of light may change on propagation, even in free space. More than 100 papers on this topic have been published to date and many of them are reviewed, or at least mentioned, in this article. After an introduction and a summary of some of the main mathematical results relating to second-order coherence theory of statistically stationary optical fields, spectral changes that may take place on superposing fields produced by two partially correlated sources are discussed. Spectral effects in fields produced by two-dimensional secondary sources and by three-dimensional primary sources are then considered. The section which follows describes spectral changes that may arise when polychromatic light is scattered on media whose physical properties vary randomly either in space and/or in time. A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another. In the final section a brief review is given of a new emerging technique sometimes called spatial-coherence spectroscopy. It is based on the discovery that it is possible, under certain circumstances, to determine field correlations from spectral measurements.
Preselected Sub-Poissonian Correlations
NASA Technical Reports Server (NTRS)
Pavicic, Mladen
1996-01-01
The simplest possible photon-number-squeezed states containing only two photons and exhibiting sub-poissonian statistics with the Fano factor approaching 0.5 have been used for a proposal of a loophole-free Bell experiment requiring only 67 percent of detection efficiency. The states are obtained by the fourth order interference first of two downconverted photons at an asymmetrical beam splitter and thereupon of two photons from two independent singlets at an asymmetrical beam splitter. In the latter set-up, the other two photons which nowhere interacted and whose paths never crossed appear entangled in a singlet-like correlated state.
Correlation dimension of complex networks.
Lacasa, Lucas; Gómez-Gardeńes, Jesús
2013-04-19
We propose a new measure to characterize the dimension of complex networks based on the ergodic theory of dynamical systems. This measure is derived from the correlation sum of a trajectory generated by a random walker navigating the network, and extends the classical Grassberger-Procaccia algorithm to the context of complex networks. The method is validated with reliable results for both synthetic networks and real-world networks such as the world air-transportation network or urban networks, and provides a computationally fast way for estimating the dimensionality of networks which only relies on the local information provided by the walkers. PMID:23679650
Multi-boson correlation sampling
NASA Astrophysics Data System (ADS)
Tamma, Vincenzo; Laibacher, Simon
2015-11-01
We give a full description of the problem of multi-boson correlation sampling (MBCS) at the output of a random interferometer for single input photons in arbitrary multi-mode pure states. The MBCS problem is the task of sampling at the interferometer output from the probability distribution associated with polarization- and time-resolved detections. We discuss the richness of the physics and the complexity of the MBCS problem for non-identical input photons. We also compare the MBCS problem with the standard boson sampling problem, where the input photons are assumed to be identical and the system is "classically" averaging over the detection times and polarizations.
Noise on Fluorescence Correlation Spectroscopy.
Starchev; Ricka; Buffle
2001-01-01
The time dependence of the noise and the signal-to-noise (SN) ratio of the fluorescence correlation spectroscopy (FCS) autocorrelation function is obtained from replica measurements of standard dextran solutions. The noise dependence on the delay time is fitted by a hyperbolic function with two fitting parameters. The dependence of these parameters on concentration, fluorescence intensity, and accumulation time is obtained experimentally. The behavior of SN at zero delay time agrees well with the theoretical predictions reported in the literature. The obtained data are useful for the quantitative evaluation of the FCS data fits, as well as for simulation of the FCS autocorrelation functions. Copyright 2001 Academic Press. PMID:11112305
Speeding up local correlation methods
Kats, Daniel
2014-12-28
We present two techniques that can substantially speed up the local correlation methods. The first one allows one to avoid the expensive transformation of the electron-repulsion integrals from atomic orbitals to virtual space. The second one introduces an algorithm for the residual equations in the local perturbative treatment that, in contrast to the standard scheme, does not require holding the amplitudes or residuals in memory. It is shown that even an interpreter-based implementation of the proposed algorithm in the context of local MP2 method is faster and requires less memory than the highly optimized variants of conventional algorithms.
The crystallography of correlated disorder
NASA Astrophysics Data System (ADS)
Keen, David A.; Goodwin, Andrew L.
2015-05-01
Classical crystallography can determine structures as complicated as multi-component ribosomal assemblies with atomic resolution, but is inadequate for disordered systems--even those as simple as water ice--that occupy the complex middle ground between liquid-like randomness and crystalline periodic order. Correlated disorder nevertheless has clear crystallographic signatures that map to the type of disorder, irrespective of the underlying physical or chemical interactions and material involved. This mapping hints at a common language for disordered states that will help us to understand, control and exploit the disorder responsible for many interesting physical properties.
Development of "active correlation" technique
NASA Astrophysics Data System (ADS)
Tsyganov, Yu. S.
2016-01-01
With reaching to extremely high intensities of heavy-ion beams new requirements for the detection system of the Dubna Gas-Filled Recoil Separator (DGFRS) will definitely be set. One of the challenges is how to apply the "active correlations" method to suppress beam associated background products without significant losses in the whole long-term experiment efficiency value. Different scenarios and equations to develop the method according this requirement are under consideration in the present paper. The execution time to estimate the dead time parameter associated with the optimal choice of the life-time parameter is presented.
EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Ronning, Filip; Batista, Cristian
2011-03-01
Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010â€”co-chaired by John Sarrao and Joe Thompsonâ€”followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed during SCES 2010. As we learned, past dogmas about strongly correlated materials and phenomena must be re-examined with an open and inquisitive mind. Invited speakers and respected leaders in the field were invited to contribute to this special issue and we have insisted that they present new data, ideas, or perspectives, as opposed to simply an overview of their past work. As with the conference, this special issue touches upon recent developments of strongly correlated electron systems in d-electron materials, such as Sr3Ru2O7, graphene, and the new Fe-based superconductors, but it is dominated by topics in f-electron compounds. Contributions reflect the growing appreciation for the influence of disorder and frustration, the need for organizing principles, as well as detailed investigations on particular materials of interest and, of course, new materials. As this special issue could not possibly capture the full breadth and depth that the conference had to offer, it is being published simultaneously with an issue of Journal of Physics: Conference Series containing 157 manuscripts in which all poster presenters at SCES 2010 were invited to contribute. Since this special issue grew out of the 2010 SCES conference, we take this opportunity to give thanks. This conference would not have been possible without the hard work of the SCES 2010 Program Committee, International and National Advisory Committees, Local Committee, and conference organizers, the New Mexico Consortium. We thank them as well as those organizations that generously provided financial support: ICAM-I2CAM, Quantum Design, Lakeshore, the National High Magnetic Field Laboratory and the Department of Energy National Laboratories at Argonne, Berkeley, Brookhaven, Los Alamos and Oak Ridge. Of course, we especially thank the participants for bringing new ideas and new results, without which SCES 2010 would not have been possible. Strongly correlated electron systems contents Spin-orbit coupling and k-dependent Zeeman splitting in strontium ruthenate Emil J Rozbicki, James F Annett, Jean-RenĂ© Souquet and Andrew P Mackenzie Thermodynamics of itinerant metamagnetic transitions A M Berridge Magnon-mediated pairing and isotope effect in iron-based superconductors Jiansheng Wu and Philip Phillips Nernst quantum oscillations in bulk semi-metals Zengwei Zhu, Huan Yang, Aritra Banerjee, Liam Malone, BenoĂ®t FauquĂ© and Kamran Behnia Signatures of a quantum Griffiths phase in a d-metal alloy close to its ferromagnetic quantum critical point Almut Schroeder, Sara Ubaid-Kassis and Thomas Vojta Influence of super-ohmic dissipation on a disordered quantum critical point Thomas Vojta, JosĂ© A Hoyos, Priyanka Mohan and Rajesh Narayanan The van Hemmen-Kondo model for disordered cerium systems S G Magalhaes, F M Zimmer and B Coqblin Chemical pressure, dilution and disorder in the heavy fermion compounds Ce3 - xLaxPd20Si6 (x = 1/3, 2/3) H Winkler, K-A Lorenzer, S Laumann, J Custers, A Prokofiev and S Paschen Magnetism of fine particles of Kondo lattices, obtained by high-energy ball-milling E V Sampathkumaran, K Mukherjee, Kartik K Iyer, Niharika Mohapatra and Sitikantha D Das Heavy fermion scaling: uranium versus cerium and ytterbium compounds J M Lawrence, C H Wang, A D Christianson and E D Bauer Temperature dependence of hybridization gaps in metallic heavy-fermion systems Xiaodong Yang, Peter S Riseborough and Tomasz Durakiewicz Low-energy properties of the Kondo lattice model O Bodensiek, R Ĺ˝itko, R Peters and T Pruschke Temperature dependence of the zero-bias anomaly in the Anderson-Hubbard model: insights from an ensemble of two-site systems R Wortis and W A Atkinson A charge density wave in the hidden order state of URu2Si2 Jung-Jung Su, Yonatan Dubi, Peter WĂ¶lfle and Alexander V Balatsky Field-induced suppression of the heavy-fermion state in YbRh2Si2 Gertrud Zwicknagl Discontinuous Hall coefficient at the quantum critical point in YbRh2Si2 Sven Friedemann, Niels Oeschler, Steffen Wirth, Cornelius Krellner, Christoph Geibel, Frank Steglich, Silke Paschen, Stefan Kirchner and Qimiao Si Roles of critical valence fluctuations in Ce- and Yb-based heavy fermion metals Shinji Watanabe and Kazumasa Miyake Unconventional quantum criticality in the pressure-induced heavy-fermion superconductor CeRhIn5 Tuson Park, V A Sidorov, H Lee, F Ronning, E D Bauer, J L Sarrao and J D Thompson Magnetic structure of the antiferromagnetic Fulde-Ferrell-Larkin-Ovchinnikov state Youichi Yanase and Manfred Sigrist Magnetic transition and spin fluctuations in the unconventional antiferromagnetic compound Yb3Pt4 S Zhao, D E MacLaughlin, O O Bernal, J M Mackie, C Marques, Y Janssen and M C Aronson The non-centrosymmetric heavy fermion ferromagnet Sm2Fe12P7 M Janoschek, R E Baumbach, J J Hamlin, I K Lum and M B Maple Magnetic, thermal, and transport properties of the actinide based noncentrosymmetric compounds Th2Fe12P7 and U2Fe12P7 R E Baumbach, J J Hamlin, M Janoschek, I K Lum and M B Maple Magnetic order in Pu2M3Si5 (M = Co, Ni) E D Bauer, P H Tobash, J N Mitchell, J A Kennison, F Ronning, B L Scott and J D Thompson
Kinoshita, Rumiko; Nam, Jin-Min; Ito, Yoichi M.; Hatanaka, Kanako C.; Hashimoto, Ari; Handa, Haruka; Otsuka, Yutaro; Hashimoto, Shigeru; Onodera, Yasuhito; Hosoda, Mitsuchika; Onodera, Shunsuke; Shimizu, Shinichi; Tanaka, Shinya; Shirato, Hiroki; Tanino, Mishie; Sabe, Hisataka
2013-01-01
A major problem of current cancer research and therapy is prediction of tumor recurrence after initial treatment, rather than the simple biological characterization of the malignancy and proliferative properties of tumors. Breast conservation therapy (BCT) is a well-approved, standard treatment for patients with early stages of breast cancer, which consists of lumpectomy and whole-breast irradiation. In spite of extensive studies, only 'age' and 'Ki-67 positivity' have been identified to be well correlated with local recurrence after BCT. An Arf6 pathway, activated by GEP100 under receptor tyrosine kinases (RTKs) and employs AMAP1 as its effector, is crucial for invasion and metastasis of some breast cancer cells. This pathway activates ?1 integrins and perturbs E-cadherin-based adhesions, hence appears to be integral for epithelial-mesenchymal transdifferentiation (EMT). We here show that expression of the Arf6 pathway components statistically correlates with rapid local recurrence after BCT. We retrospectively analyzed four hundred seventy-nine patients who received BCT in Hokkaido University Hospital, and found 20 patients had local recurrence. We then analyzed pathological samples of patients who experienced local recurrence by use of Kaplan-Meier analysis, Stepwise regression analysis and the t-test, coupled with immunostaining, and found that co-overexpression of GEP100 and AMAP1 correlates with rapidity of the local recurrence. Their margin-status, node-positivity, and estrogen receptor (ER)- or progesterone receptor (PgR)-positivity did not correlated with the rapidity. This study is the first to show that expression of a certain set of proteins correlates with the rapidity of local recurrence. Our results are useful not only for prediction, but highlight the possibility of developing novel strategies to block local recurrence. We also discuss why mRNAs encoding these proteins have not been identified to correlate with local recurrence by previous conventional gene expression profiling analyses. PMID:24116160
NASA Technical Reports Server (NTRS)
Pasham, Dheeraj R.; Strohmayer, Tod E.
2013-01-01
Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.
Wang, Dong-liang; Liu, Yan-yan; Gu, Yuan-long; Qin, Yu; Ji, Hong-fei; Wu, Li-hua; Qi, Ning; Su, Dan; Huang, Sun-hui; Zhang, Yan-qiao
2015-07-01
Tumor-infiltrating lymphocytes (TILs) that test positive for forkhead box P3 (FOXP3) and elevated preoperative serum albumin levels have been positively associated with survival in colorectal cancer (CRC). This study aimed to investigate correlations among FOXP3+ TILs, preoperative serum albumin, overall survival, and other clinicopathological features of CRC patients. Surgical specimens from 340 stage II-III CRC patients were stained immunohistochemically for the presence of FOXP3+ TILs. Serum albumin levels were determined using an automatic biochemistry analyzer. Associations between various clinicopathological features and patient survival were analyzed via a Cox proportional hazards regression model. The correlation between FOXP3+ TILs and preoperative serum albumin was assessed using Pearson's correlation analysis. Survival curves were constructed by the Kaplan-Meier method. A high FOXP3+ TIL density (>15/five high-power fields), elevated preoperative serum albumin (?35 g/L), and proximal colon carcinoma were significantly associated with better survival, and high FOXP3+ TIL number and elevated preoperative serum albumin were independent predictors of better survival. The correlation between the number of FOXP3+ TILs and preoperative serum albumin level was significant but neither of these correlated with gender, age, tumor size, tumor differentiation, mucinous tumor, T4 stage, postoperative chemotherapy, or tumor location. Our findings suggest that increased FOXP3+ TILs and high preoperative serum albumin levels are independent prognostic markers for improved survival in CRC patients. Furthermore, the number of FOXP3+ TILs correlates with preoperative serum albumin levels in these patients. PMID:25697896
Correlation of phantom-based and log file patient-specific QA with complexity scores for VMAT.
Agnew, Christina E; Irvine, Denise M; McGarry, Conor K
2014-01-01
The motivation for this study was to reduce physics workload relating to patient- specific quality assurance (QA). VMAT plan delivery accuracy was determined from analysis of pre- and on-treatment trajectory log files and phantom-based ionization chamber array measurements. The correlation in this combination of measurements for patient-specific QA was investigated. The relationship between delivery errors and plan complexity was investigated as a potential method to further reduce patient-specific QA workload. Thirty VMAT plans from three treatment sites - prostate only, prostate and pelvic node (PPN), and head and neck (H&N) - were retrospectively analyzed in this work. The 2D fluence delivery reconstructed from pretreatment and on-treatment trajectory log files was compared with the planned fluence using gamma analysis. Pretreatment dose delivery verification was also car- ried out using gamma analysis of ionization chamber array measurements compared with calculated doses. Pearson correlations were used to explore any relationship between trajectory log file (pretreatment and on-treatment) and ionization chamber array gamma results (pretreatment). Plan complexity was assessed using the MU/ arc and the modulation complexity score (MCS), with Pearson correlations used to examine any relationships between complexity metrics and plan delivery accu- racy. Trajectory log files were also used to further explore the accuracy of MLC and gantry positions. Pretreatment 1%/1 mm gamma passing rates for trajectory log file analysis were 99.1% (98.7%-99.2%), 99.3% (99.1%-99.5%), and 98.4% (97.3%-98.8%) (median (IQR)) for prostate, PPN, and H&N, respectively, and were significantly correlated to on-treatment trajectory log file gamma results (R = 0.989, p < 0.001). Pretreatment ionization chamber array (2%/2 mm) gamma results were also significantly correlated with on-treatment trajectory log file gamma results (R = 0.623, p < 0.001). Furthermore, all gamma results displayed a significant correlation with MCS (R > 0.57, p < 0.001), but not with MU/arc. Average MLC position and gantry angle errors were 0.001 ± 0.002 mm and 0.025° ± 0.008° over all treatment sites and were not found to affect delivery accuracy. However, vari- ability in MLC speed was found to be directly related to MLC position accuracy. The accuracy of VMAT plan delivery assessed using pretreatment trajectory log file fluence delivery and ionization chamber array measurements were strongly correlated with on-treatment trajectory log file fluence delivery. The strong corre- lation between trajectory log file and phantom-based gamma results demonstrates potential to reduce our current patient-specific QA. Additionally, insight into MLC and gantry position accuracy through trajectory log file analysis and the strong cor- relation between gamma analysis results and the MCS could also provide further methodologies to both optimize the VMAT planning and QA process. PMID:25493524
Correlated metals as transparent conductors.
Zhang, Lei; Zhou, Yuanjun; Guo, Lu; Zhao, Weiwei; Barnes, Anna; Zhang, Hai-Tian; Eaton, Craig; Zheng, Yuanxia; Brahlek, Matthew; Haneef, Hamna F; Podraza, Nikolas J; Chan, Moses H W; Gopalan, Venkatraman; Rabe, Karin M; Engel-Herbert, Roman
2016-02-01
The fundamental challenge for designing transparent conductors used in photovoltaics, displays and solid-state lighting is the ideal combination of high optical transparency and high electrical conductivity. Satisfying these competing demands is commonly achieved by increasing carrier concentration in a wide-bandgap semiconductor with low effective carrier mass through heavy doping, as in the case of tin-doped indium oxide (ITO). Here, an alternative design strategy for identifying high-conductivity, high-transparency metals is proposed, which relies on strong electron-electron interactions resulting in an enhancement in the carrier effective mass. This approach is experimentally verified using the correlated metals SrVO3 and CaVO3, which, despite their high carrier concentration (>2.2 × 10(22)?cm(-3)), have low screened plasma energies (<1.33?eV), and demonstrate excellent performance when benchmarked against ITO. A method is outlined to rapidly identify other candidates among correlated metals, and strategies are proposed to further enhance their performance, thereby opening up new avenues to develop transparent conductors. PMID:26657329
Correlation dimension-based classifier.
Jirina, Marcel; Jirina, Marcel
2014-12-01
Correlation dimension (CD), singularity exponents, also called scaling exponents, are widely used in multifractal chaotic series analysis. CD and other measures of effective dimensionality are used for characterization of data in applications. A direct use of CD to multidimensional data classification has not been hitherto presented. There are observations that the correlation integral is a distribution function of distances between all pairs of data points, and that by using polynomial expansion of distance with exponent equal to the CD this distribution is transformed into locally uniform. The classifier is based on consideration that the influence of neighbor points of some class on the probability that the query point belongs to this class is inversely proportional to its distance to the CD, power. New classification approach is based on summing up all these influences for each class. We prove that a resulting formula gives an estimate of probability of the class, not a measure of membership to a class only, to which the query point belongs. For this assertion to be valid, it is necessary that exponent of the polynomial transformation must be the CD. We also propose an averaging approach that speeds up computation of the CD especially for large data sets. It is demonstrated that the CD-based classifier can outperform more sophisticated classifiers. PMID:25415936
PREFACE: Correlation Dynamics in Nuclei
NASA Astrophysics Data System (ADS)
Suzuki, Toshio; Otsuka, Takaharu; Ichimura, Munetake
2005-01-01
The International Symposium on `Correlation Dynamics in Nuclei' was held at the Sanjo Kaikan, the University of Tokyo, from the 31 January to 4 February 2005. This symposium was organized on the occasion of the 50th anniversary of the Configuration Mixing theory of Arima and Horie. The symposium was hosted by the University of Tokyo, and supported by the Inoue Foundation for Science, the Japan Atomic Energy Research Institute and the Ministry of Education, Culture, Sports, Science and Technology. The purpose of the symposium was to discuss theoretical and experimental developments and future prospects in physics of correlation dynamics in nuclei, including topics such as effective interactions, shell model studies of configuration mixing and spin-isospin modes in nuclei. It was shown in many ways and angles that the Arima-Horie theory has been a starting point of a variety of developments of the studies in these fields over many decades. The developments have been enhanced by the expansion of computational capabilities and the progress in accelerators, detectors and radioactive beam facilities. We enjoyed 28 excellent and lively invited talks and 30 oral presentations in the symposium with about 90 participants. A special session was dedicated to celebrate the 80th birthday of Professor Igal Talmi, who made invaluable and pioneering works in the shell model theory. Finally, we would like to thank all the speakers and the participants as well as the other organizers for their contributions which made the symposium very successful.
Correlated metals as transparent conductors
NASA Astrophysics Data System (ADS)
Zhang, Lei; Zhou, Yuanjun; Guo, Lu; Zhao, Weiwei; Barnes, Anna; Zhang, Hai-Tian; Eaton, Craig; Zheng, Yuanxia; Brahlek, Matthew; Haneef, Hamna F.; Podraza, Nikolas J.; Chan, Moses H. W.; Gopalan, Venkatraman; Rabe, Karin M.; Engel-Herbert, Roman
2016-02-01
The fundamental challenge for designing transparent conductors used in photovoltaics, displays and solid-state lighting is the ideal combination of high optical transparency and high electrical conductivity. Satisfying these competing demands is commonly achieved by increasing carrier concentration in a wide-bandgap semiconductor with low effective carrier mass through heavy doping, as in the case of tin-doped indium oxide (ITO). Here, an alternative design strategy for identifying high-conductivity, high-transparency metals is proposed, which relies on strong electron-electron interactions resulting in an enhancement in the carrier effective mass. This approach is experimentally verified using the correlated metals SrVO3 and CaVO3, which, despite their high carrier concentration (>2.2 Ă— 1022 cm-3), have low screened plasma energies (<1.33 eV), and demonstrate excellent performance when benchmarked against ITO. A method is outlined to rapidly identify other candidates among correlated metals, and strategies are proposed to further enhance their performance, thereby opening up new avenues to develop transparent conductors.
The dynamics of correlated novelties
NASA Astrophysics Data System (ADS)
Tria, F.; Loreto, V.; Servedio, V. D. P.; Strogatz, S. H.
2014-07-01
Novelties are a familiar part of daily life. They are also fundamental to the evolution of biological systems, human society, and technology. By opening new possibilities, one novelty can pave the way for others in a process that Kauffman has called ``expanding the adjacent possible''. The dynamics of correlated novelties, however, have yet to be quantified empirically or modeled mathematically. Here we propose a simple mathematical model that mimics the process of exploring a physical, biological, or conceptual space that enlarges whenever a novelty occurs. The model, a generalization of Polya's urn, predicts statistical laws for the rate at which novelties happen (Heaps' law) and for the probability distribution on the space explored (Zipf's law), as well as signatures of the process by which one novelty sets the stage for another. We test these predictions on four data sets of human activity: the edit events of Wikipedia pages, the emergence of tags in annotation systems, the sequence of words in texts, and listening to new songs in online music catalogues. By quantifying the dynamics of correlated novelties, our results provide a starting point for a deeper understanding of the adjacent possible and its role in biological, cultural, and technological evolution.
The dynamics of correlated novelties.
Tria, F; Loreto, V; Servedio, V D P; Strogatz, S H
2014-01-01
Novelties are a familiar part of daily life. They are also fundamental to the evolution of biological systems, human society, and technology. By opening new possibilities, one novelty can pave the way for others in a process that Kauffman has called "expanding the adjacent possible". The dynamics of correlated novelties, however, have yet to be quantified empirically or modeled mathematically. Here we propose a simple mathematical model that mimics the process of exploring a physical, biological, or conceptual space that enlarges whenever a novelty occurs. The model, a generalization of Polya's urn, predicts statistical laws for the rate at which novelties happen (Heaps' law) and for the probability distribution on the space explored (Zipf's law), as well as signatures of the process by which one novelty sets the stage for another. We test these predictions on four data sets of human activity: the edit events of Wikipedia pages, the emergence of tags in annotation systems, the sequence of words in texts, and listening to new songs in online music catalogues. By quantifying the dynamics of correlated novelties, our results provide a starting point for a deeper understanding of the adjacent possible and its role in biological, cultural, and technological evolution. PMID:25080941
ASTROCHEMICAL CORRELATIONS IN MOLECULAR CLOUDS
Gaches, Brandt A. L.; Offner, Stella S. R.; Rosolowsky, Erik W.; Bisbas, Thomas G. E-mail: soffner@astro.umass.edu E-mail: tb@star.ucl.ac.uk
2015-02-01
We investigate the spectral correlations between different species used to observe molecular clouds. We use hydrodynamic simulations and a full chemical network to study the abundances of over 150 species in typical Milky Way molecular clouds. We perform synthetic observations in order to produce emission maps of a subset of these tracers. We study the effects of different lines of sight and spatial resolution on the emission distribution and perform a robust quantitative comparison of the species to each other. We use the Spectral Correlation Function (SCF), which quantifies the root mean squared difference between spectra separated by some length scale, to characterize the structure of the simulated cloud in position-position-velocity (PPV) space. We predict the observed SCF for a broad range of observational tracers, and thus identify homologous species. In particular, we show that the pairs C and CO, C{sup +} and CN, and NH{sub 3} and H{sub 2}CS have very similar SCFs. We measure the SCF slope variation as a function of beam size for all species and demonstrate that the beam size has a distinct effect on different species emission. However, for beams of up to 10'', placing the cloud at 1 kpc, the change is not large enough to move the SCF slopes into different regions of parameter space. The results from this study provide observational guidance for choosing the best tracer to probe various cloud length scales.
The Neurogenetic Correlates of Consciousness
NASA Astrophysics Data System (ADS)
Grandy, John K.
2013-09-01
The neurogenetic correlates of consciousness (NgCC) is a new field of consciousness studies that focuses on genes that have an effect on or are involved in the continuum of neuron-based consciousness. A framework of consciousness based on the neural correlates of consciousness (NCC) has already been established by Francis Crick and Christof Kock. In this work I propose that there are NgCC underlying the NCC which are both active during the conscious experience. So how are genes involved? There are two significant connections between DNA and neurons that are involved in the conscious experience. First, any brain system can be adversely affected by underlying genetic abnormalities which can be expressed in an individual at birth, in adulthood, or later in life. Second, the DNA molecule does not lay dormant while the neuron runs on autopilot. DNA is active in translating and transcribing RNA and protein products that are utilized during neuron functioning. Without these products being continuously produced by the DNA during a conscious experience the neurons would cease to function correctly and be rendered unable to provide a continuum of human consciousness. Consequently, in addition to NCC, NgCC must be factored in when appreciating a conscious event. In this work I will discuss and explain some NgCC citing several examples.
Fiducial marker for correlating images
Miller, Lisa Marie (Rocky Point, NY); Smith, Randy J. (Wading River, NY); Warren, John B. (Port Jefferson, NY); Elliott, Donald (Hampton Bays, NY)
2011-06-21
The invention relates to a fiducial marker having a marking grid that is used to correlate and view images produced by different imaging modalities or different imaging and viewing modalities. More specifically, the invention relates to the fiducial marking grid that has a grid pattern for producing either a viewing image and/or a first analytical image that can be overlaid with at least one other second analytical image in order to view a light path or to image different imaging modalities. Depending on the analysis, the grid pattern has a single layer of a certain thickness or at least two layers of certain thicknesses. In either case, the grid pattern is imageable by each imaging or viewing modality used in the analysis. Further, when viewing a light path, the light path of the analytical modality cannot be visualized by viewing modality (e.g., a light microscope objective). By correlating these images, the ability to analyze a thin sample that is, for example, biological in nature but yet contains trace metal ions is enhanced. Specifically, it is desired to analyze both the organic matter of the biological sample and the trace metal ions contained within the biological sample without adding or using extrinsic labels or stains.
Correlations in cosmic density fields
NASA Technical Reports Server (NTRS)
Bromley, B. C.
1994-01-01
A method is proposed to place constraints on the functional form of the high-order correlation functions zeta(sub n) that arise in cosmic density fields at large scales. This technique is based on a mass-in-cell statistic and a difference of mass in partitions of a cell. The relationship between these measures is sensitive to the formal structure of the zeta(sub n) as well as their amplitudes. This relationship is quantified in several theoretical models of structure, based on the hierarchical clustering paradigm. The results lead to a test for specific types of hierarchical clustering that is sensitive to correlations of all orders. The method is applied to examples of simulated large-scaled structure dominated by cold dark matter. In the preliminary study, the hierarchical paradigm appears to be a realistic approximation over a broad range of the scales. Furthermore, there is evidence that graphs of low-order vertices are dominant. On the basis of simulated data a phenomological model is specified that gives a good representation of clustering from linear scales to the strongly clustered regime (zeta(sub 2) approximately 500).
Dipolar correlations in liquid water
Zhang, Cui; Galli, Giulia
2014-08-28
We present an analysis of the dipolar correlations in water as a function of temperature and density and in the presence of simple ionic solutes, carried out using molecular dynamics simulations and empirical potentials. We show that the dipole-dipole correlation function of the liquid exhibits sizable oscillations over nanodomains of about 1.5 nm radius, with several isosbestic points as a function of temperature; the size of the nanodomains is nearly independent on temperature and density, between 240 and 400Â K and 0.9 and 1.3 g/cm{sup 3}, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (Ď„) of the system dipole moment varies by a factor of about 30 and 1.5, as a function of temperature and density, respectively. At 300 K, we observed a maximum in Ď„ as a function of density, and a corresponding shallow maximum in the tetrahedral order parameter, in a range where the diffusion coefficient, the pressure and the dielectric constant increase monotonically.
Development of Software Correlator for KJJVC
NASA Astrophysics Data System (ADS)
Yeom, J. H.; Oh, S. J.; Roh, D. G.; Kang, Y. W.; Park, S. Y.; Lee, C. H.; Chung, H. S.
2009-12-01
Korea-Japan Joint VLBI Correlator (KJJVC) is being developed by collaborating KASI (Korea Astronomy and Space Science Institute), Korea, and NAOJ(National Observatory of Japan), Japan. In early 2010, KJJVC will work in normal operation. In this study, we developed the software correlator which is based on VCS (VLBI Correlation Subsystem) hardware specification as the core component of KJJVC. The main specification of software correlator is 8 Gbps, 8192 output channels, and 262,144-points FFT (Fast Fourier Transform) function same as VCS. And the functional algorithm which is same as specification of VCS and arithmetic register are adopted in this software correlator. To verify the performance of developed software correlator, the correlation experiments were carried out using the spectral line and continuum sources which were observed by VERA (VLBI Exploration of Radio Astrometry), NAOJ. And the experimental results were compared to the output of Mitaka FX correlator by referring spectrum shape, phase rate, and fringe detection and so on. Through the experimental results, we confirmed that the correlation results of software correlator are the same as Mitaka FX correlator and verified the effectiveness of it. In future, we expect that the developed software correlator will be the possible software correlator of KVN (Korean VLBI Network) with KJJVC by introducing the correlation post-processing and modifying the user interface as like GUI (Graphic User Interface).
Measurement and Correlation of Ambient VOCs in Windsor, Ontario, Canada and Detroit, Michigan, USA
NASA Astrophysics Data System (ADS)
Miller, L. J.; You, H.; Xu, X.; Molaroni, S.; Lemke, L.; Weglicki, L.; Krouse, H.; Krajenta, R.
2009-05-01
An air quality study has been carried out in Windsor, Ontario, Canada and Detroit, Michigan, USA as part of a pilot research study undertaken by the Geospatial Determinants of Health Outcomes Consortium (GeoDHOC), a multidisciplinary, international effort aimed at understanding the health effects of air pollution in urban environments. Exposure to volatile organic compounds has long been associated with adverse health conditions such as atrophy of skeletal muscles, loss of coordination, neurological damage, dizziness, throat, nose, and eye irritation, nervous system depression, liver damage, and respiratory symptoms. Twenty-six species of ambient volatile organic compounds (VOCs) were monitored during a 2-week period in September, 2008 at 100 sites across Windsor and Detroit, using 3M # 3500 Organic Vapour Monitors. Ten species with highest concentrations were selected for further investigation; Toluene (mean concentration =4.14 ?m/m3), (m+p)-Xylene (2.30 ?m/m3), Hexane (1.87 ?m/m3), Benzene (1.37 ?m/m3), 1,2,4-Trimethylbenzene (0.87 ?m/m3), Dichloromethane (0.77 ?m/m3), Ethylbenzene (0.68 ?m/m3), o-Xylene (0.63 ?m/m3), n-Decane (0.42 ?m/m3), and 1,3,5-Trimethylbenzene (0.39 ?m/m3). Comparison to a similar investigation in Sarnia, Ontario in October 2005 revealed that the mean concentrations of VOCs were higher in Windsor-Detroit for all species by a significant margin (31-958%), indicating substantial impact of local industrial and vehicular emissions in the WindsorVDetroit area. For most VOCs, the concentrations were higher in Detroit than in Windsor. The mean concentration of total VOC was 9.7 ?m/m3 in Windsor, which is slightly higher than that in Sarnia in 2005 (7.9 um/m3), whilst total VOC concentration in Detroit was much higher (16.5 ?m/m3). There were strong correlations among several of the 10 species, with the highest Pearson correlation coefficients (r=0.78 - 0.99, p<0.05) amongst the BTEX (benzene, toluene, ethylbenzene, and xylenes) group, suggesting common sources of these species. The BTEX correlation for this study was in good agreement with that from the Sarnia results (Spearman rank correlation coefficient r=0.75 - 0.99), suggesting that one species may act as a proxy for the others in geographically similar regions.
Angularly anisotropic correlation in granular packings
Xia, Chengjie; Cao, Yixin; Kou, Binquan; Li, Jindong; Wang, Yujie; Xiao, Xianghui; Fezzaa, Kamel
2014-12-01
We present an x-ray microtomography study of the three-dimensional structural correlations in monodisperse granular packings. By measuring an orientation-dependent pair correlation function, we find that the local structure shows an angularly anisotropic orientation correlation. The correlation is strongest along the major axis of the local Minkowski tensor of the Voronoi cell. It turns out that this anisotropic correlation is consistent with the existence of some locally favored structures. The study suggests the importance of high-order structural correlations in random granular packings.
Target tracking using area correlation
NASA Astrophysics Data System (ADS)
Jackson, R. M. B.
1980-11-01
The tracking system described based on the area correlator technique can provide a stable and accurate track of targets for use in airborne systems in conjunction with FLIR or TV imagers. It is a small size and can be built into standard format packages for installation in military aircraft. The main advantages of this technique are: (1) it can handle targets with a wide range of characteristics; (2) it can track background features to provide a ground reference; (3) it does not require that the edges of the target are within the tracking patches and it can handle targets which completely fill the field of view; (4) it can adapt automatically to magnification and target aspect changes; and (5) it provides highly tenacious tracking in low signal to noise conditions.
Vertical velocity-CCN correlations
NASA Astrophysics Data System (ADS)
Hudson, J. G.; Noble, S. R.
2013-12-01
The realization that smaller cloud droplets evaporate more readily (Xue and Feingold 2006; Jiang et al. 2002) gives rise to an anti-indirect aerosol effect (IAE); less cloudiness with pollution. The greater latent heat exchange of the greater evaporation in more polluted clouds adds TKE and buoyancy gradients that can enhance vertical velocity (W), mixing and entrainment (Zhao and Austin 2005). Stronger W can increase horizontal motions, which can further enhance droplet evaporation, which further enhances latent heat exchange and vertical motions, thus, positive feedback. This could also include latent heat released during condensation (Lee and Feingold 2010), which is more rapid for the greater surface areas of the smaller more numerous droplets. These theories imply a positive relationship between within-cloud W variations; i.e., standard deviation of W (?w) and CCN concentration (NCCN) rather than W and NCCN. This implies greater turbulence in polluted clouds, which could possibly counteract the reduction of cloudiness of anti-IAE. During two stratus cloud projects, 50 cloud penetrations in 9 MASE flights and 34 cloud penetrations in 13 POST flights, within-cloud ?w-NCCN showed correlation coefficients (R) of 0.50 and 0.39. Panel a shows similar within-cloud ?w-NCCN R in all altitude bands for 17 RICO flights in small cumulus clouds. R for W-NCCN showed similar values but only at low altitudes. Out-of-cloud ?w-NCCN showed similar high values except at the highest altitudes. Within-cloud ?w showed higher R than within-cloud W with droplet concentrations (Nc), especially at higher altitudes. Panel b for 13 ICE-T cumulus cloud flights in the same location as RICO but during the opposite season, however, showed ?w and W uncorrelated with NCCN at all altitudes; and W and ?w correlated with Nc only at the highest altitudes. On the other hand, out-of-cloud ?w was correlated with NCCN at all altitudes with R similar to the corresponding R of the other projects. Overall these results are consistent with the theories noted above. Supported by NSF AGS-1035230 and DOE SC0009162. Jiang, H., G. Feingold, and W.R. Cotton, 2002: J. Geophys. Res, 107, D24, 4813. Lee, S.-S., and G. Feingold, 2010: Geophys. Res. Lett., 37, L23806. Xue, H., and G. Feingold, 2006: J. Atmos. Sci., 63, 1605-1622. Zhao, M., and P.H. Austin, 2005: J. Atmos. Sci., 62, 1291-1310. Fig. Correlation coefficients (R) between mean and standard deviations of vertical velocity (W; ?w within and outside of clouds) with CCN concentrations at 1% supersaturation (N1%) measured below the clouds and with droplet concentrations (Nc) within various altitude bands.
Correlating thalamocortical connectivity and activity
NASA Astrophysics Data System (ADS)
da Fontoura Costa, Luciano; Sporns, Olaf
2006-07-01
The segregated regions of the mammalian cerebral cortex and thalamus form an extensive and complex network, whose structure and function are still only incompletely understood. The present letter describes an application of the concepts of complex networks and random walks that allows the identification of nonrandom, highly structured features of thalamocortical connections and their potential effects on dynamic interactions between cortical areas in the cat brain. Utilizing large-scale anatomical data sets of this thalamocortical system, we investigate uniform random walks in such a network by considering the steady state eigenvector of the respective stochastic matrix. It is shown that thalamocortical connections are organized in such a way as to guarantee strong correlation between the outdegree and occupancy rate (a stochastic measure potentially related to activation) of each cortical area. Possible organizational principles underlying this effect are identified and discussed.
CORRELATIONS IN CONFINED QUANTUM PLASMAS
DUFTY J W
2012-01-11
This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed
Vibration analysis using digital correlation
NASA Technical Reports Server (NTRS)
Gilbert, John A.; Lehner, David L.; Dudderar, T. Dixon; Matthys, Donald R.
1988-01-01
This paper demonstrates the use of a computer-based optical method for locating the positions of nodes and antinodes in vibrating members. Structured light patterns are projected at an angle onto the vibrating surface using a 35 mm slide projector. The vibrating surface and the projected images are captured in a time averaged photograph which is subsequently digitized. The inherent fringe patterns are filtered to determine amplitudes of vibration, and computer programs are used to compare the time averaged images to images recorded prior to excitation to locate nodes and antinodes. Some of the influences of pattern regularity on digital correlation are demonstrated, and a speckle-based method for determining the mode shapes and the amplitudes of vibration with variable sensitivity is suggested.
Physiological correlates of mental workload
NASA Technical Reports Server (NTRS)
Zacharias, G. L.
1980-01-01
A literature review was conducted to assess the basis of and techniques for physiological assessment of mental workload. The study findings reviewed had shortcomings involving one or more of the following basic problems: (1) physiologic arousal can be easily driven by nonworkload factors, confounding any proposed metric; (2) the profound absence of underlying physiologic models has promulgated a multiplicity of seemingly arbitrary signal processing techniques; (3) the unspecified multidimensional nature of physiological "state" has given rise to a broad spectrum of competing noncommensurate metrics; and (4) the lack of an adequate definition of workload compels physiologic correlations to suffer either from the vagueness of implicit workload measures or from the variance of explicit subjective assessments. Using specific studies as examples, two basic signal processing/data reduction techniques in current use, time and ensemble averaging are discussed.
Correlation method of electrocardiogram analysis
NASA Astrophysics Data System (ADS)
Strinadko, Marina M.; Timochko, Katerina B.
2002-02-01
The electrocardiograph method is the informational source for functional heart state characteristics. The electrocardiogram parameters are the integrated map of many component characteristics of the heart system and depend on disturbance requirements of each device. In the research work the attempt of making the skeleton diagram of perturbation of the heart system is made by the characteristic description of its basic components and connections between them through transition functions, which are written down by the differential equations of the first and second order with the purpose to build-up and analyze electrocardiogram. Noting the vector character of perturbation and the various position of heart in each organism, we offer own coordinate system connected with heart. The comparative analysis of electrocardiogram was conducted with the usage of correlation method.
Investigation of correlation classification techniques
NASA Technical Reports Server (NTRS)
Haskell, R. E.
1975-01-01
A two-step classification algorithm for processing multispectral scanner data was developed and tested. The first step is a single pass clustering algorithm that assigns each pixel, based on its spectral signature, to a particular cluster. The output of that step is a cluster tape in which a single integer is associated with each pixel. The cluster tape is used as the input to the second step, where ground truth information is used to classify each cluster using an iterative method of potentials. Once the clusters have been assigned to classes the cluster tape is read pixel-by-pixel and an output tape is produced in which each pixel is assigned to its proper class. In addition to the digital classification programs, a method of using correlation clustering to process multispectral scanner data in real time by means of an interactive color video display is also described.
The Effect of Error Correlation on Interfactor Correlation in Psychometric Measurement
ERIC Educational Resources Information Center
Westfall, Peter H.; Henning, Kevin S. S.; Howell, Roy D.
2012-01-01
This article shows how interfactor correlation is affected by error correlations. Theoretical and practical justifications for error correlations are given, and a new equivalence class of models is presented to explain the relationship between interfactor correlation and error correlations. The class allows simple, parsimonious modeling of error…
Welker, Kelli L; Orkin, Joseph D; Ryan, Timothy M
2009-01-01
The semicircular canal system tracks head rotation and provides sensory input for the reflexive stabilization of gaze and posture. The purpose of this study was to investigate the intraspecific and intraindividual variation in the size of the three semicircular canals. The right and left temporal bones were extracted from 31 individuals of the short-tailed shrew (Blarina brevicauda) and scanned on a high-resolution x-ray computed tomography system. The radius of curvature was calculated for each of the three semicircular canals for each side. Paired t-tests and independent sample t-tests indicated no significant differences in canal size between the right and left canals of the same individuals or between those of males and females of the same species. Pearson product moment correlation analyses demonstrated that there was no significant correlation between canal size and body mass in this sample. PMID:19619167
Mustafa, Dana A. M.; Sieuwerts, Anieta M.; Smid, Marcel; de Weerd, Vania; van der Weiden, Marcel; Meijer - van Gelder, Marion E.; Martens, John W. M.; Foekens, John A.; Kros, Johan M.
2015-01-01
Background Gene expression profiling of tumors is a successful tool for the discovery of new cancer biomarkers and potential targets for the development of new therapeutic strategies. Reliable profiling is preferably performed on fresh frozen (FF) tissues in which the quality of nucleic acids is better preserved than in formalin-fixed paraffin-embedded (FFPE) material. However, since snap-freezing of biopsy materials is often not part of daily routine in pathology laboratories, one may have to rely on archival FFPE material. Procedures to retrieve the RNAs from FFPE materials have been developed and therefore, datasets obtained from FFPE and FF materials need to be made compatible to ensure reliable comparisons are possible. Aim To develop an efficient method to compare gene expression profiles obtained from FFPE and FF samples using the same platform. Methods Twenty-six FFPE-FF sample pairs of the same tumors representing various cancer types, and two FFPE-FF sample pairs of breast cancer cell lines, were included. Total RNA was extracted and gene expression profiling was carried out using Illuminaâ€™s Whole-Genome cDNA-mediated Annealing, Selection, extension and Ligation (WG-DASL) V3 arrays, enabling the simultaneous detection of 24,526 mRNA transcripts. A sample exclusion criterion was created based on the expression of 11 stably expressed reference genes. Pearson correlation at the probe level was calculated for paired FFPE-FF, and three cut-off values were chosen. Spearman correlation coefficients between the matched FFPE and FF samples were calculated for three probe lists with varying levels of significance and compared to the correlation based on all measured probes. Unsupervised hierarchical cluster analysis was performed to verify performance of the included probe lists to compare matched FPPE-FF samples. Results Twenty-seven FFPE-FF pairs passed the sample exclusion criterion. From the profiles of 27 FFPE and FF matched samples, the best correlating probes were identified for various levels of significance (Pearson P<0.01, n = 1,432; P<0.05, n = 2,530; and P<0.10, n = 3,351 probes). Unsupervised hierarchical clustering of the 27 pairs using the resulting probes yielded 25, 21, and 19 correctly clustered pairs, respectively, compared to 1 pair when all probes were used. Conclusion The proposed method enables comparison of gene expression profiles of FFPE and/or FF origin measured on the same platform. PMID:26716838
Motunrayo Ibrahim, Fausat
2013-01-01
Background: Gardening is a worthwhile adventure which engenders health optimization. Yet, a dearth of evidences that highlights motivations to engage in gardening exists. This study examined willingness to engage in gardening and its correlates, including some socio-psychological, health related and socio-demographic variables. Methods: In this cross-sectional survey, 508 copies of a structured questionnaire were randomly self administered among a group of civil servants of Oyo State, Nigeria. Multi-item measures were used to assess variables. Step wise multiple regression analysis was used to identify predictors of willingness to engage in gardening Results: Simple percentile analysis shows that 71.1% of respondents do not own a garden. Results of step wise multiple regression analysis indicate that descriptive norm of gardening is a good predictor, social support for gardening is better while gardening self efficacy is the best predictor of willingness to engage in gardening (P< 0.001). Health consciousness, gardening response efficacy, education and age are not predictors of this willingness (P> 0.05). Results of t-test and ANOVA respectively shows that gender is not associated with this willingness (P> 0.05), but marital status is (P< 0.05). Conclusion: Socio-psychological characteristics and being married are very relevant in motivations to engage in gardening. The nexus between gardening and health optimization appears to be highly obscured in this population. PMID:24688974
Correlation of pregnancy outcome with quadruple screening test at second trimester
Yazdani, Shahla; Rouholahnejad, Rahele; Asnafi, Nesa; Sharbatdaran, Majid; Zakershob, Marziihe; Bouzari, Zinatossadat
2015-01-01
Background: Abnormal levels of the markers AFP, hCG, and uE3 could be useful in predicting adverse pregnancy outcomes. This study was designed to determine the correlation between second trimester maternal serum markers and adverse pregnancy outcome (APO). Methods: In this historical cohort study, we randomly followed 231 obstetric patients with quadruple screening test in 14-18 weeks of gestation from March 2012 to March 2013 in a medical laboratory in Babol, Iran. We measured maternal serum levels of alphafetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and inhibin-A. The risk of adverse pregnancy outcomes (APOs) were then compared between patients with negative and positive test results. We used Chi-square and Fisher-exact tests for qualitative variables and t-test for quantitative variables. Demographic differences between the two groups were minimized by applying logistic regression. Results: The risk of having an APO such as pre-eclampsia (p=0.008), fetal growth restriction (p=0.028) and premature rupture of membrane (p=0.040) increased significantly in patients with abnormal markers. Conclusion: Abnormal results of quadruple screening test could be associated with APO in women with normal appearing fetus. PMID:26913244