For comprehensive and current results, perform a real-time search at Science.gov.

1

The relation between Pearson's correlation coefficient r and Salton's cosine measure

The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which form together a cloud of points, being the investigated relation. The theoretical results are tested against the author co-citation relations among 24 informetricians for whom two matrices can be constructed, based on co-citations: the asymmetric occurrence matrix and the symmetric co-citation matrix. Both examples completely confirm the theoretical results. The results enable us to specify an algorithm which provides a threshold value for the cosine above which none of the corresponding Pearson correlations would be negative. Using this threshold value can be expected to optimize the visualization of the vector space.

Egghe, Leo

2009-01-01

2

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

3

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

4

SPSS and SAS programs for comparing Pearson correlations and OLS regression coefficients.

Several procedures that use summary data to test hypotheses about Pearson correlations and ordinary least squares regression coefficients have been described in various books and articles. To our knowledge, however, no single resource describes all of the most common tests. Furthermore, many of these tests have not yet been implemented in popular statistical software packages such as SPSS and SAS. In this article, we describe all of the most common tests and provide SPSS and SAS programs to perform them. When they are applicable, our code also computes 100 × (1 - ?)% confidence intervals corresponding to the tests. For testing hypotheses about independent regression coefficients, we demonstrate one method that uses summary data and another that uses raw data (i.e., Potthoff analysis). When the raw data are available, the latter method is preferred, because use of summary data entails some loss of precision due to rounding. PMID:23344734

Weaver, Bruce; Wuensch, Karl L

2013-09-01

5

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

Booma, P M; Prabhakaran, S; Dhanalakshmi, R

2014-01-01

6

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

Graña, M; Termenon, M; Savio, A; Gonzalez-Pinto, A; Echeveste, J; Pérez, J M; Besga, A

2011-09-20

7

This paper extends results on the distribution of the Fisher transform of the correlation coefficient (Fisher, 1921). Approaches to obtain exact moments of the Fisher transform for both null and non-null correlations are presented. We extend the classic series expansion formulae of Hotelling (1953) for the moments of the Fisher transform. These results are considered in the context of quadratic

Rachel T. Fouladi; James H. Steiger

2008-01-01

8

Paired t testsPaired t tests Paired (dependent) t-testPaired (dependent) t test

Paired t testsPaired t tests #12;Paired (dependent) t-testPaired (dependent) t test Â· Compares test means from matched pairsCompares test means from matched pairs or two different samples from the same individualsindividuals Â e.g., pretest & post test scores for the same group of students Ho: d = 0 d is thedifference

Wolverton, Steve

9

NSDL National Science Digital Library

This page gives a short background on Student's t-test and provides three t-test calculators. Two perform t-tests for independent groups and one performs t-tests for matched pairs. Users type in individual data points or copy and paste the entire data set. Some examples are given for demonstration.

Kirkman, Thomas

2008-12-24

10

Pearson's Functions to Describe FSW Weld Geometry

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.

Lacombe, D.; Coupard, D.; Tcherniaeff, S. [Arts et Metiers ParisTech, LAMEFIP, Esplanade des Arts et Metiers, 33405 Talence Cedex (France); Girot, F. [IKERBASQUE, Basque Foundation for Science, Bilbao (Spain); Gutierrez-Orrantia, M. E.

2011-01-17

11

An outstanding issue in graph-based analysis of resting-state functional MRI is choice of network nodes. Individual consideration of entire brain voxels may represent a less biased approach than parcellating the cortex according to pre-determined atlases, but entails establishing connectedness for 1(9)-1(11) links, with often prohibitive computational cost. Using a representative Human Connectome Project dataset, we show that, following appropriate time-series normalization, it may be possible to accelerate connectivity determination replacing Pearson correlation with l1-norm. Even though the adjacency matrices derived from correlation coefficients and l1-norms are not identical, their similarity is high. Further, we describe and provide in full an example vector hardware implementation of l1-norm on an array of 4096 zero instruction-set processors. Calculation times <1000 s are attainable, removing the major deterrent to voxel-based resting-sate network mapping and revealing fine-grained node degree heterogeneity. L1-norm should be given consideration as a substitute for correlation in very high-density resting-state functional connectivity analyses. PMID:25023958

Minati, Ludovico; Zacà, Domenico; D'Incerti, Ludovico; Jovicich, Jorge

2014-09-01

12

NSDL National Science Digital Library

This page will perform a t-test for the significance of the difference between the observed mean of a sample and a hypothetical mean of the population from which the sample is randomly drawn. The user will be asked to specify the sample size as the page opens.

Lowry, Richard, 1940-

2008-09-05

13

Pearson's Functions to Describe FSW Weld Geometry

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

D. Lacombe; M. E. Gutierrez-Orrantia; D. Coupard; S. Tcherniaeff; F. Girot

2011-01-01

14

Reviews 32 papers on correlation its methods, interpretation and application. Highlights the contributions of K. Pearson, B. Hart and C. Spearman, and W. H. Winch. W. Betz's publications concludes that correlation alone does not demonstrate a functional connection and serves the purpose of (1) describing educational or social descriptions of Large groups, and (2) discovering functional connections when used with

James Burt Miner

1912-01-01

15

Pearson and Pedagogy: Countering Co-Dependency

ERIC Educational Resources Information Center

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…

Fielder, John

2008-01-01

16

NCS Pearson: Scanning the Diet History Questionnaire

NCS Pearson is one source of scannable DHQ forms and scanning services. See Scanning the DHQ for information regarding other sources. Any new information we know of regarding economical printing, scanning, or data entry methods will be posted on this Web site as it becomes available.

17

The Pearson-Readhead Survey from Space

NASA Technical Reports Server (NTRS)

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.

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

18

1 James Pearson Duffy Department of Art and Art History James Pearson Duffy Department of Art and Art History 150 Art Building Detroit, Michigan 48202 Telephone: (313) 577-2980 Fax: (313) 577: (313) 577-2980 Designing the Wild and Cultivating the City The James Pearson Duffy Department of Art

Berdichevsky, Victor

19

NSDL National Science Digital Library

This section, part of a larger site produced by the School of Psychology at the University of New England, focuses on "Common Statistical Tests" using an example on faculty publications to show users how to perform a one-sample t test. Additionally, there is a discussion that includes one-tailed and two-tailed tests.

Price, Ian

2009-01-13

20

Robust Mixture Modeling with Pearson Type VII Distribution

Robust Mixture Modeling with Pearson Type VII Distribution Jianyong Sun, and Jonathan M. Garibaldi, Member, IEEE Abstract-- Mixture of Student t-distribution (MoT) has been widely used to model developed a novel robust clustering approach by modeling the data sets with mixture of Pearson type VII

Aickelin, Uwe

21

2015 Pearson Education, Inc. Chapter 2 Solar Energy to Earth

ï¿½ 2015 Pearson Education, Inc. Chapter 2 Solar Energy to Earth and the Seasons #12;ï¿½ 2015 Pearson of the solar wind. ï¿½ Explain the characteristics of the electromagnetic spectrum of radiant energy. ï¿½ Illustrate the interception of solar energy and its uneven distribution at the top of the atmosphere

Pan, Feifei

22

2015 Pearson Education, Inc. Chapter 3 Earth's Modern Atmosphere

. Air Pressure Altitude Low High Pressure 0 Green /Area (Green + Blue)/Area (Green + Blue + Red)/Area Air pressure decreases with increase of altitude. #12;Atmospheric Pressure Profile #12;ï¿½ 2015 Pearson, Tasteless, and Formless Air #12;ï¿½ 2015 Pearson Education, Inc. The thickness of the Earth's atmosphere

Pan, Feifei

23

2015 Pearson Education, Inc. Chapter 1. Essentials of Geography

aspects of the universe work. ï¿½ This approach is called the "scientific method." #12;ï¿½ 2015 Pearson Education, Inc. The Scientific Method #12;ï¿½ 2015 Pearson Education, Inc. Scientific Method theory consistent activities and human population growth as they relate to geographic science, and summarize the scientific

Pan, Feifei

24

Exam scores by range Copyright 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 3-1

points (surveys and questions) as they are weighted at 5% of the total points Â which is a big swing. 3 its height. C i t ti d b tit t Copyright Â© 2007 Pearson Education, Inc. Publishing as Pearson Addison

Allan, Vicki H.

25

Sensitivity analysis of Welch's t-test

NASA Astrophysics Data System (ADS)

Welch t-test is the parametric test for comparing means between two independent groups without assuming equal population variances. This statistic is robust for testing the mean equality when homogeneity assumption is not satisfied, but Welch test is not always robust. When multiple problems such as the distribution is non-normal, variance is heterogeneous and unequal size of groups occur simultaneously, the Type I error will inflate. In this study, various conditions such as sample sizes, type of distributions and unequal group variances were manipulated to investigate on the non robust conditions of Welch test. The Type I error rates and power of the test for different design specifications were obtained and compared. The results indicated that this test did not perform well under non-normal distributions especially when group sizes and unequal group variances are inversely associated or negatively paired. The estimated Type I error inflated as the power of the test improved.

Ahad, Nor Aishah; Yahaya, Sharipah Soaad Syed

2014-07-01

26

Karl Pearson and eugenics: personal opinions and scientific rigor.

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

Delzell, Darcie A P; Poliak, Cathy D

2013-09-01

27

2005 Pearson Education Inc., publishing as Addison-Wesley

5 The Moon, Our Constant Companion >the Moon's orbit around the Earth #12;Â© 2005 Pearson Education > the wobbling of Earth's axis 5 The Moon, Our Constant Companion >the Moon's orbit around the Earth 6., publishing as Addison-Wesley France: Cave paintings from 18,000 B.C. may suggest knowledge of lunar phases

Shirley, Yancy

28

2005 Pearson Education Inc., publishing as Addison-Wesley

;Â· The Voyager spacecraft Â the farthest human craft from the Earth has taken almost 25 years to reach the edgeÂ© 2005 Pearson Education Inc., publishing as Addison-Wesley Scales of Space and Time #12;Â© 2005-Wesley Galaxy A great island of stars in space, all held together by gravity and orbiting a common center M31

Shirley, Yancy

29

2005 Pearson Education Inc., publishing as Addison-Wesley

-Wesley #12;Â· The Voyager spacecraft Â the farthest human craft from the Earth has taken almost 25 yearsÂ© 2005 Pearson Education Inc., publishing as Addison-Wesley Scales of Space and Time #12;Â© 2005 Â· The visible universe is the size of the U.S. Â· Billions of galaxies within this space = #12;The Milky Way

Shirley, Yancy

30

2005 Pearson Education South Asia Pte Ltd Applied Fluid Mechanics

Number, Laminar Flow, Turbulent Flow and Energy Losses Due to Friction Â©2005 Pearson Education South Asia through such fittings as tees and wyes and through flow control devices. Â· The units used for the various. Buoyancy and Stability 6. Flow of Fluid and Bernoulli's Equation 7. General Energy Equation 8. Reynolds

Leu, Tzong-Shyng "Jeremy"

31

Valuing Stocksg Copyright 2011 Pearson Prentice Hall. All rights reserved.

Describe the impact of efficient markets hypothesis on12. Describe the impact of efficient markets the return the average investor should expect to get. 14. Assess the impact of stock valuation on recommended flows are risky, we must discount them at the equity cost of capital. Copyright ï¿½ 2011 Pearson Prentice

Schubart, Christoph

32

Biostatistik, WS 2013/2014 Der zwei-Stichproben-t-Test

Biostatistik, WS 2013/2014 Der zwei-Stichproben-t-Test (t-Test fÂ¨ur ungepaarte Stichproben;1 Wiederholung: Ein-Stichproben-t-Test 2 t-Test fÂ¨ur ungepaarte Stichproben Beispiel: BackenzÂ¨ahne von Hipparions Allgemein: ungepaarter t-Test mit Annahme gleicher Varianzen Bericht: t-Test ohne Annahme gleicher Varianz

Birkner, Matthias

33

Biostatistik, WS 2010/2011 Der zwei-Stichproben-t-Test

Biostatistik, WS 2010/2011 Der zwei-Stichproben-t-Test (t-Test fÂ¨ur ungepaarte Stichproben;1 Wiederholung: Ein-Stichproben-t-Test 2 t-Test fÂ¨ur ungepaarte Stichproben Beispiel: BackenzÂ¨ahne von Hipparions Allgemein: ungepaarter t-Test mit Annahme gleicher Varianzen Bericht: t-Test ohne Annahme gleicher Varianz

Birkner, Matthias

34

Shape modeling with family of Pearson distributions: Langmuir waves

NASA Astrophysics Data System (ADS)

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.

Vidojevic, Sonja

2014-10-01

35

Research Methods Knowledge Base : The t-Test

NSDL National Science Digital Library

This particular textbook lesson, presented by Cornell University's Research Methods Knowledge Base, addresses the independent t-test. It presents to the user how to compute the t statistic and then how to interpret the results. The site uses graphs and charts along with the text to enhance the presentation. Overall, this is a useful resource for any mathematics classroom.

Trochim, William M.

2008-12-26

36

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\\u000a and their intentions to not use substances. The students were participating in a substance use prevention program in which\\u000a the unit of randomization was a public middle school. The

David A. Wagstaff; Elvira Elek; Stephen Kulis; Flavio Marsiglia

2009-01-01

37

Robust mixture clustering using Pearson type VII distribution q Jianyong Sun a,d,

Robust mixture clustering using Pearson type VII distribution q Jianyong Sun a,d, , Ata KabÃ¡n b December 2008 Available online xxxx Communicated by W. Pedrycz Keywords: Robust mixture modeling Pearson type VII distribution Outlier detection Robust learning a b s t r a c t A mixture of Student t

Kaban, Ata

38

Robust mixture clustering using Pearson type VII distribution q Jianyong Sun a,d,

Robust mixture clustering using Pearson type VII distribution q Jianyong Sun a,d, , Ata Kabï¿½n b December 2008 Available online 10 August 2010 Communicated by W. Pedrycz Keywords: Robust mixture modeling Pearson type VII distribution Outlier detection Robust learning a b s t r a c t A mixture of Student t

Aickelin, Uwe

39

ART DEPARTMENT GALLERY James Pearson Duffy Department of Art and Art History

1 ART DEPARTMENT GALLERY James Pearson Duffy Department of Art and Art History 5400 Reuther Mall, 150 Art Building Detroit, Michigan 48202 Telephone: (313) 577-0770 Fax: (313) 577-8935 FOR IMMEDIATE. Pyrzewski (tpyrzewski@wayne.edu) The James Pearson Duffy Department of Art and Art History's Art Department

Cinabro, David

40

Reviews 16 publications (1913-1914) based on the problem of correlations. Correlation is viewed as a means of solving the problem of development and the traits that are affected. The uses of correlations are also discussed. A high correlation does not signify good quality of the two factors. A more intensive study of the factors influencing correlation is recommended. Cites a

James Burt Miner

1914-01-01

41

Reviews 38 studies on statistical correlation (1913-1916). Several studies have tried to explain and investigate Spearman's theory of general and specific mental factors in terms of correlation. The interpretation of correlation through heredity has also been discussed by investigators. A number of methods such as partial and multiple correlations, variant difference correlation method, and several others have been devised. The

James Burt Miner

1916-01-01

42

Reviews 7 studies in the area of interpretation of correlation from the psychological point of view. The limitations and meanings of correlation methods have also been given. The statistical methods of calculating correlation, as given by 8 psychologists have been reported. Presents 22 reports, given by various psychologists, who have evaluated the tests using various correlation methods. Six studies were

James Burt Miner

1919-01-01

43

Delayed correlation between turbulent energy injection and dissipation Bruce R. Pearson*

to one- dimensional surrogacy as there is for experiments. Notwith- standing this fact, there is good previously reported simulations but in good agreement with experimental results. If C is estimated, aspect of turbulence modeling. The rate of turbulent kinetic energy dissipation is deter- mined

Brandenburg, Axel

44

A new method for improving functional-to-structural MRI alignment using local Pearson correlation

Accurate registration of Functional Magnetic Resonance Imaging (FMRI) T2?-weighted volumes to same-subject high-resolution T1-weighted structural volumes is important for Blood Oxygenation Level Dependent (BOLD) FMRI and crucial for applications such as cortical surface-based analyses and pre-surgical planning. Such registration is generally implemented by minimizing a cost functional, which measures the mismatch between two image volumes over the group of proper

Ziad S. Saad; Daniel R. Glen; Gang Chen; Michael S. Beauchamp; Rutvik Desai; Robert W. Cox

2009-01-01

45

NSDL National Science Digital Library

The applets, created by Virginia Tech's Department of Statistics, allow you to see how different bivariate data look under different correlation structures. The "Movie" applet either creates data for a particular correlation or animates a multitude data sets ranging correlations from -1 to 1. The "Creation" applet allows the user to create a data set by adding or deleting points from the screen.

Anderson-Cook, C.; Dorai-Raj, S.; Robinson, T.

2009-09-14

46

SALD 18A: JMP examples for one-sample t-test

SALD 18A: JMP examples for one-sample t-test #12;Introduction Notes #12;DO NOT COPY Copyright calculation in JMP To perform a one-sample t-test, select from the data table main menu Analyze 18A-8 To perform a one-sample t-test in JMP, first perform a distribution analysis Under Select

Morgan, Stephen L.

47

t-Test: The Good, the Bad, the Ugly, & the Remedy

ERIC Educational Resources Information Center

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…

Zhang, Guili

2009-01-01

48

Discusses: (1) the need for a general factor to explain the correlation between tested psychophysical processes and (2) the importance of multiple correlation in solving the complex problems. Reports the contributions of Thurstone, Ruml and Kelley to the methods of calculation of coefficients. Doll offers new ways of using corrections. Applications of this method in new fields other than applied

James Burt Miner

1917-01-01

49

Examines the use of various methods of correlations, for determining the diagnostic value of tests, used in analysis of abilities, in business psychology, mental development and school records. Also reviews a number of studies done in this regard.

James Burt Miner

1918-01-01

50

NASA Astrophysics Data System (ADS)

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 ?2 statistic. We evaluate the performance of the two measures by using a controlled MALDI-TOF experiment. The results indicate that Pearson's ?2 statistic has better discriminatory performance than the Mahalanobis distance and is a more robust measure.

Zamanzad Ghavidel, Fatemeh; Claesen, Jürgen; Burzykowski, Tomasz; Valkenborg, Dirk

2013-11-01

51

Three recent studies (Pearson, 2012; Pearson, Ross, & Webster, 2012) purported to test the revised dual representation theory of posttraumatic stress disorder (Brewin, Gregory, Lipton, & Burgess, 2010) by manipulating the amount of additional information accompanying traumatic stimulus materials and assessing the effect on subsequent intrusive memories. Here we point out that these studies involve a misunderstanding of the meaning of “contextual” within the theory, such that the manipulation would be unlikely to have had the intended effect and the results are ambiguous with respect to the theory. Past and future experimental tests of the theory are discussed. PMID:24041427

Brewin, Chris R.; Burgess, Neil

2014-01-01

52

A spirit of conservatism and caution in regard to intelligence test correlations animates numerous papers. Several writers urge the use of units of rank orders, in the estimating of mental abilities. (See, Boring, McEwen, Michael and the Scott Laboratory). Several others like Ruml, Myers, Mitchell, Thorndike and Thompson hold various views in favor of or in criticism against numerous concepts

J. B. Miner

1920-01-01

53

Children with autism do not overimitate L. Marsh, A. Pearson, D. Ropar & A. Hamilton

Children with autism do not overimitate L. Marsh, A. Pearson, D. Ropar & A. Hamilton School object, typically developing (TD) children faithfully copy both necessary and visibly unnecessary actions to be causally transparent in their mechanism, young children's causal reasoning about novel objects is unclear

Hamilton, Antonia

54

A Pearson-Type-VII Item Response Model for Assessing Person Fluctuation

ERIC Educational Resources Information Center

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…

Ferrando, Pere J.

2007-01-01

55

Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Nature of Life

it to form many diverse molecules, varying in length and shape Carbon is Special #12;Copyright Â© 2005 Pearson molecules possessing both amino group [N bonded to 2 H and 1 C] and carboxyl group [COOH] Â·Differ carbon, hydrogen, oxygen, and nitrogen Â· Make up 96% of living matter Â·A few other elements Â·Make up

Shirley, Yancy

56

Tactile SLAM with a biomimetic whiskered robot Charles Fox, Mat Evans, Martin Pearson and Tony Supported by FP7 BIOTACT (ICT-215910) and EFAA (ICT-270490). Fox, Evans and Prescott are with the Sheffield of whisker sensors without mul- tiscan or rectilinear assumptions. Unlike infra-red or sonar sensors, which

Barker, Jon

57

ERIC Educational Resources Information Center

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'…

Pae, Hye K.

2012-01-01

58

Test Statistics Derived as Components of Pearson's Phi-Squared Distance Measure

A general approach to the comparison of two absolutely continuous distributions is presented based on Pearson's ? measure. Although no simple estimates are available for ?, it can be decomposed into components, all of which are easily estimated. Asymptotic distribution theory is derived for the component estimates, and the form of the components is considered for several standard problems. It

R. L. Eubank; V. N. Lariccia; R. B. Rosenstein

1987-01-01

59

James Pearson Duffy Department of Art and Art History Elaine L. Jacob Gallery

1 James Pearson Duffy Department of Art and Art History Elaine L. Jacob Gallery 480 W. Hancock of Art and Art History's Elaine L. Jacob Gallery is pleased to present SILENT WATCH: CONTEMPORARY PRINTS as several artists' books and a three-dimensional piece. The exhibition includes prints by the widely

Berdichevsky, Victor

60

Photosynthesis in Aspen Bark Author(s): L. C. Pearson and D. B. Lawrence

Photosynthesis in Aspen Bark Author(s): L. C. Pearson and D. B. Lawrence Reviewed work(s): Source and extend access to American Journal of Botany. http://www.jstor.org #12;PHOTOSYNTHESIS IN ASPEN BARK1 L. C earlierthanthe others.By May 17 seed dispersalwas complete.The leaves had reachedmaximumsize by June7

Minnesota, University of

61

Fast R Functions for Robust Correlations and Hierarchical Clustering

Many high-throughput biological data analyses require the calculation of large correlation matrices and\\/or clustering of a large number of objects. The standard R function for calculating Pearson correlation can handle calculations without missing values efficiently, but is inefficient when applied to data sets with a relatively small number of missing data. We present an implementation of Pearson correlation calculation that

Peter Langfelder; Steve Horvath

2012-01-01

62

Using the Student's "t"-Test with Extremely Small Sample Sizes

ERIC Educational Resources Information Center

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…

de Winter, J. C .F.

2013-01-01

63

The primary stability of dental implants is fundamental for osseointegration. Therefore, this study aimed to assess the correlation between insertion torque (IT) and resonance frequency analysis (RFA) of implants placed in mandibles and maxillas of different bone densities. Eighty dental implants were placed in maxillas and mandibles, and IT and the implant stability quotient (ISQ) were measured at the time of implant insertion. Bone density was assessed subjectively by the Lekholm and Zarb index. The type I and II densities were grouped together (group A)as were the type III and IV densities (group B). The IT in group A was higher (Student t test, P = .0013) than in group B (46.27 ± 18.51 Ncm, 33.62 ± 14.74 Ncm, respectively). The implants placed in group A showed higher ISQ (Student t test, P = .0004) than those placed in group B (70.09 ± 7.50, 63.66 ± 8.00, respectively). A significant correlation between IT and the ISQ value was observed for group A (Pearson correlation test; r = 0.35; P = .0213) and for group B (r = 0.37; P = .0224). Within the limitations of this study, it was possible to conclude that there is a correlation between IT and RFA of implants placed in mandibles and maxillas of different bone densities. PMID:24914911

Filho, Luiz Carlos Magno; Cirano, Fabiano Ribeiro; Hayashi, Fernando; Feng, Hsu Shao; Conte, Alexandre; Dib, Luciano Lauria; Casati, Marcio Zaffalon

2014-06-01

64

BOOK REVIEWS 77 Michel Foucault, Fearless Speech. Edited by Joseph Pearson. (Los Angeles: Semiotext(e), 2001), 183 pages. Andrew Knighton University of Minnesota In a 1986 conversation with Robert Maggiori (published in English... begins to provoke concern; he locates that point in Euripedes' differing treatment of the phenomenon in Ion and Orestes. In the former—the most crucial parrhesiastic play—Euripedes stresses the human agency implied by parrhesia. In Ion, Apollo conceals...

Knighton, Andrew

2003-01-01

65

NASA Astrophysics Data System (ADS)

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.

Singh, Vijay P.; Singh, Kulwant

1985-10-01

66

Correlations between Pre-morbid Personality and Depression Scales in Stroke Patients

Objective To investigate the correlation between pre-morbid personality and depression scales in patients with stroke. Method The subjects of this study included 45 patients with stroke and their caregivers. We conducted an interview of patients with Beck Depression Inventory (BDI) and also evaluated general characteristic (age, sex, location of lesion, cause of stroke, duration of illness, educational background, history of medication for depression) and functional level. Caregivers were evaluated with Hamilton Rating Scale for Depression (HRSD) for depressive mood, with NEO-PI (Neuroticism, Extraversion and Openness Personality Inventory) for pre-morbid personality. The results of each questionnaire were analyzed in order to investigate their correlation. The results were statistically analyzed with independent t-test, ANOVA, and Pearson correlation test. Results The HRSD score of the caregivers had a significant correlation with the BDI score (p=0.001) of the patients. The BDI score correlated with Neuroticism (p=0.021) and the HRSD score also correlated with Neuroticism (p=0.015). There were no statistical correlation of depression with sex, age, case of stroke, location of lesion, duration of illness and functional level. Conclusion Among pre-morbid personalities, neuroticism of NEO-PI is the only factor which is significantly correlated with depression scales in stroke patients. Evaluating pre-morbid personality can be helpful in predicting the depressive mood in stroke patients, so we may have early intervention for it. PMID:22506141

Hwang, Sung Il; Park, Oak Tae; Park, Si-Woon; Choi, Eun Seok; Yi, Sook-Hee

2011-01-01

67

Laser plasma x-ray line spectra fitted using the Pearson VII function

NASA Astrophysics Data System (ADS)

The Pearson VII function, which is more general than the Gaussian, Lorentzian and other profiles, is used to fit the x-ray spectral lines produced in a laser-generated plasma, instead of the more usual, but computationally expensive, Voigt function. The mean full-width half-maximum of the fitted lines is 0.102+/-0.014 nm, entirely consistent with the value expected from geometrical considerations, and the fitted line profiles are generally inconsistent with being either Lorentzian or Gaussian.

Michette, A. G.; Pfauntsch, S. J.

2000-05-01

68

Pearson-type goodness-of-fit test with bootstrap maximum likelihood estimation.

The Pearson test statistic is constructed by partitioning the data into bins and computing the difference between the observed and expected counts in these bins. If the maximum likelihood estimator (MLE) of the original data is used, the statistic generally does not follow a chi-squared distribution or any explicit distribution. We propose a bootstrap-based modification of the Pearson test statistic to recover the chi-squared distribution. We compute the observed and expected counts in the partitioned bins by using the MLE obtained from a bootstrap sample. This bootstrap-sample MLE adjusts exactly the right amount of randomness to the test statistic, and recovers the chi-squared distribution. The bootstrap chi-squared test is easy to implement, as it only requires fitting exactly the same model to the bootstrap data to obtain the corresponding MLE, and then constructs the bin counts based on the original data. We examine the test size and power of the new model diagnostic procedure using simulation studies and illustrate it with a real data set. PMID:23720703

Yin, Guosheng; Ma, Yanyuan

2013-01-01

69

Pearson-type goodness-of-fit test with bootstrap maximum likelihood estimation

The Pearson test statistic is constructed by partitioning the data into bins and computing the difference between the observed and expected counts in these bins. If the maximum likelihood estimator (MLE) of the original data is used, the statistic generally does not follow a chi-squared distribution or any explicit distribution. We propose a bootstrap-based modification of the Pearson test statistic to recover the chi-squared distribution. We compute the observed and expected counts in the partitioned bins by using the MLE obtained from a bootstrap sample. This bootstrap-sample MLE adjusts exactly the right amount of randomness to the test statistic, and recovers the chi-squared distribution. The bootstrap chi-squared test is easy to implement, as it only requires fitting exactly the same model to the bootstrap data to obtain the corresponding MLE, and then constructs the bin counts based on the original data. We examine the test size and power of the new model diagnostic procedure using simulation studies and illustrate it with a real data set. PMID:23720703

Yin, Guosheng; Ma, Yanyuan

2013-01-01

70

40 CFR Appendix IV to Part 264 - Cochran's Approximation to the Behrens-Fisher Students' t-test

Code of Federal Regulations, 2011 CFR

...Approximation to the Behrens-Fisher Students' t-test IV Appendix IV to Part 264 ...Approximation to the Behrens-Fisher Students' t-test Using all the available background...of observations in the set of data. The t-test uses these data summary measures...

2011-07-01

71

40 CFR Appendix IV to Part 264 - Cochran's Approximation to the Behrens-Fisher Students' t-test

Code of Federal Regulations, 2012 CFR

...Approximation to the Behrens-Fisher Students' t-test IV Appendix IV to Part 264 ...Approximation to the Behrens-Fisher Students' t-test Using all the available background...of observations in the set of data. The t-test uses these data summary measures...

2012-07-01

72

40 CFR Appendix IV to Part 264 - Cochran's Approximation to the Behrens-Fisher Students' t-test

Code of Federal Regulations, 2010 CFR

...Approximation to the Behrens-Fisher Students' t-test IV Appendix IV to Part 264 ...Approximation to the Behrens-Fisher Students' t-test Using all the available background...of observations in the set of data. The t-test uses these data summary measures...

2010-07-01

73

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

74

A new correlation coefficient for bivariate time-series data

NASA Astrophysics Data System (ADS)

The correlation in time series has received considerable attention in the literature. Its use has attained an important role in the social sciences and finance. For example, pair trading in finance is concerned with the correlation between stock prices, returns, etc. In general, Pearson’s correlation coefficient is employed in these areas although it has many underlying assumptions which restrict its use. Here, we introduce a new correlation coefficient which takes into account the lag difference of data points. We investigate the properties of this new correlation coefficient. We demonstrate that it is more appropriate for showing the direction of the covariation of the two variables over time. We also compare the performance of the new correlation coefficient with Pearson’s correlation coefficient and Detrended Cross-Correlation Analysis (DCCA) via simulated examples.

Erdem, Orhan; Ceyhan, Elvan; Varli, Yusuf

2014-11-01

75

Pearson marrow pancreas syndrome in patients suspected to have Diamond-Blackfan anemia.

Pearson marrow pancreas syndrome (PS) is a multisystem disorder caused by mitochondrial DNA (mtDNA) deletions. Diamond-Blackfan anemia (DBA) is a congenital hypoproliferative anemia in which mutations in ribosomal protein genes and GATA1 have been implicated. Both syndromes share several features including early onset of severe anemia, variable nonhematologic manifestations, sporadic genetic occurrence, and occasional spontaneous hematologic improvement. Because of the overlapping features and relative rarity of PS, we hypothesized that some patients in whom the leading clinical diagnosis is DBA actually have PS. Here, we evaluated patient DNA samples submitted for DBA genetic studies and found that 8 (4.6%) of 173 genetically uncharacterized patients contained large mtDNA deletions. Only 2 (25%) of the patients had been diagnosed with PS on clinical grounds subsequent to sample submission. We conclude that PS can be overlooked, and that mtDNA deletion testing should be performed in the diagnostic evaluation of patients with congenital anemia. PMID:24735966

Gagne, Katelyn E; Ghazvinian, Roxanne; Yuan, Daniel; Zon, Rebecca L; Storm, Kelsie; Mazur-Popinska, Magdalena; Andolina, Laura; Bubala, Halina; Golebiowska, Sydonia; Higman, Meghan A; Kalwak, Krzysztof; Kurre, Peter; Matysiak, Michal; Niewiadomska, Edyta; Pels, Salley; Petruzzi, Mary Jane; Pobudejska-Pieniazek, Aneta; Szczepanski, Tomasz; Fleming, Mark D; Gazda, Hanna T; Agarwal, Suneet

2014-07-17

76

Connections between permutation and t-tests: relevance to adaptive methods.

A permutation test assigns a p-value by conditioning on the data and treating the different possible treatment assignments as random. The fact that the conditional type I error rate given the data is controlled at level ? ensures validity of the test even if certain adaptations are made. We show the connection between permutation and t-tests, and use this connection to explain why certain adaptations are valid in a t-test setting as well. We illustrate this with an example of blinded sample size recalculation. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25156155

Proschan, Michael; Glimm, Ekkehard; Posch, Martin

2014-11-30

77

Determining Differences in Efficacy of Two Disinfectants Using t-Tests.

ERIC Educational Resources Information Center

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)

Brehm, Michael A.; And Others

1996-01-01

78

Five-Point Likert Items: t Test versus Mann-Whitney-Wilcoxon

ERIC Educational Resources Information Center

Likert questionnaires are widely used in survey research, but it is unclear whether the item data should be investigated by means of parametric or nonparametric procedures. This study compared the Type I and II error rates of the "t" test versus the Mann-Whitney-Wilcoxon (MWW) for five-point Likert items. Fourteen population distributions were…

de Winter, Joost C. F.; Dodou, Dimitra

2010-01-01

79

Use of "t"-Test and ANOVA in Career-Technical Education Research

ERIC Educational Resources Information Center

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…

Rojewski, Jay W.; Lee, In Heok; Gemici, Sinan

2012-01-01

80

Type I Error Rate and Power of Some Alternative Methods to the Independent Samples "t" Test.

ERIC Educational Resources Information Center

Examined Type I error rates and power for four tests for treatment control studies in which a larger treatment mean may be accompanied by a larger treatment variance and examined these aspects of the independent samples "t" test and the Welch test. Evaluated each test and suggested conditions for the use of each approach. (SLD)

Nthangeni, Mbulaheni; Algina, James

2001-01-01

81

Background Clinicians have long appreciated the distinct phenotype of systemic juvenile idiopathic arthritis (SJIA) compared to polyarticular juvenile idiopathic arthritis (POLY). We hypothesized that gene expression profiles of peripheral blood mononuclear cells (PBMC) from children with each disease would reveal distinct biological pathways when analyzed for significant associations with elevations in two markers of JIA activity, erythrocyte sedimentation rate (ESR) and number of affected joints (joint count, JC). Methods PBMC RNA from SJIA and POLY patients was profiled by kinetic PCR to analyze expression of 181 genes, selected for relevance to immune response pathways. Pearson correlation and Student's t-test analyses were performed to identify transcripts significantly associated with clinical parameters (ESR and JC) in SJIA or POLY samples. These transcripts were used to find related biological pathways. Results Combining Pearson and t-test analyses, we found 91 ESR-related and 92 JC-related genes in SJIA. For POLY, 20 ESR-related and 0 JC-related genes were found. Using Ingenuity Systems Pathways Analysis, we identified SJIA ESR-related and JC-related pathways. The two sets of pathways are strongly correlated. In contrast, there is a weaker correlation between SJIA and POLY ESR-related pathways. Notably, distinct biological processes were found to correlate with JC in samples from the earlier systemic plus arthritic phase (SAF) of SJIA compared to samples from the later arthritis-predominant phase (AF). Within the SJIA SAF group, IL-10 expression was related to JC, whereas lack of IL-4 appeared to characterize the chronic arthritis (AF) subgroup. Conclusions The strong correlation between pathways implicated in elevations of both ESR and JC in SJIA argues that the systemic and arthritic components of the disease are related mechanistically. Inflammatory pathways in SJIA are distinct from those in POLY course JIA, consistent with differences in clinically appreciated target organs. The limited number of ESR-related SJIA genes that also are associated with elevations of ESR in POLY implies that the SJIA associations are specific for SJIA, at least to some degree. The distinct pathways associated with arthritis in early and late SJIA raise the possibility that different immunobiology underlies arthritis over the course of SJIA. PMID:23092393

2012-01-01

82

NASA Astrophysics Data System (ADS)

The diagnosis of several neurological disorders is based on the detection of typical pathological patterns in electroencephalograms (EEGs). This is a time-consuming task requiring significant training and experience. A lot of effort has been devoted to developing automatic detection techniques which might help not only in accelerating this process but also in avoiding the disagreement among readers of the same record. In this work, Neyman-Pearson criteria and a support vector machine (SVM) are applied for detecting an epileptic EEG. Decision making is performed in two stages: feature extraction by computing the wavelet coefficients and the approximate entropy (ApEn) and detection by using Neyman-Pearson criteria and an SVM. Then the detection performance of the proposed method is evaluated. Simulation results demonstrate that the wavelet coefficients and the ApEn are features that represent the EEG signals well. By comparison with Neyman-Pearson criteria, an SVM applied on these features achieved higher detection accuracies.

Wang, Chun-mei; Zhang, Chong-ming; Zou, Jun-zhong; Zhang, Jian

2012-02-01

83

Measuring correlations between non-stationary series with DCCA coefficient

NASA Astrophysics Data System (ADS)

In this short report, we investigate the ability of the DCCA coefficient to measure correlation level between non-stationary series. Based on a wide Monte Carlo simulation study, we show that the DCCA coefficient can estimate the correlation coefficient accurately regardless the strength of non-stationarity (measured by the fractional differencing parameter d). For a comparison, we also report the results for the standard Pearson correlation coefficient. The DCCA coefficient dominates the Pearson coefficient for non-stationary series.

Kristoufek, Ladislav

2014-05-01

84

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

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

85

Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments

[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.

Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.

2004-01-01

86

Tuning support vector machines for minimax and Neyman-Pearson classification.

This paper studies the training of support vector machine (SVM) classifiers with respect to the minimax and Neyman-Pearson criteria. In principle, these criteria can be optimized in a straightforward way using a cost-sensitive SVM. In practice, however, because these criteria require especially accurate error estimation, standard techniques for tuning SVM parameters, such as cross-validation, can lead to poor classifier performance. To address this issue, we first prove that the usual cost-sensitive SVM, here called the 2C-SVM, is equivalent to another formulation called the 2nu-SVM. We then exploit a characterization of the 2nu-SVM parameter space to develop a simple yet powerful approach to error estimation based on smoothing. In an extensive experimental study, we demonstrate that smoothing significantly improves the accuracy of cross-validation error estimates, leading to dramatic performance gains. Furthermore, we propose coordinate descent strategies that offer significant gains in computational efficiency, with little to no loss in performance. PMID:20724764

Davenport, Mark A; Baraniuk, Richard G; Scott, Clayton D

2010-10-01

87

Professor P. P. Allport The Right Honourable Dr Ian Pearson, M.P., Head of Particle Physics and

Professor P. P. Allport The Right Honourable Dr Ian Pearson, M.P., Head of Particle Physics of the major role played by the extreme demands of particle physics in stimulating new technologies in fields with domestic large facilities unrelated to particle physics and to the implementation of Full Economic Costing

Crowther, Paul

88

ERIC Educational Resources Information Center

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…

Wagstaff, David A.; Elek, Elvira; Kulis, Stephen; Marsiglia, Flavio

2009-01-01

89

Two-Sample t-Test for Equal Means (Engineering Statistics Handbook)

NSDL National Science Digital Library

Gives textbook-like explanation with some real-life data to compute a t-test and determine if two population means are equal. Also has some links for case studies and a web-based program called Dataplot. There is a printer-friendly version on the main homepage (see source). Overall, this is a great resource for anyone interested in either engineering or mathematics.

Filliben, James; Heckert, Alan

2008-12-31

90

The selection criteria in determining the robustness of t-test

NASA Astrophysics Data System (ADS)

Robustness in the context of hypothesis testing is the ability of a procedure to control Type I error rate of a test close to the nominal value and stable over a range of distributions even with some deviations from its assumptions. Procedures that were deemed robust for some researchers could be considered not robust for others. Some researchers would consider that the procedures with conservative Type I error rates fail to perform. However, other researchers may assume otherwise, such that any value less than or equal to the nominal level can still be considered as robust. Many quantitative measures or criteria can be used to evaluate the robustness of a statistical test such as the t-test. In this study, the robustness of t-test was evaluated using five different robustness criteria. For each criteria, Type I error of the t-test was measured under different conditions namely sample sizes, group variances, type of distributions, and nature of pairings. The results showed that different robust criterion gives different interpretation on the robustness of the test and based on the result, the best robust criterion was identified.

Ahad, Nor Aishah; Yahaya, Sharipah Soaad Syed

2014-06-01

91

Matrix Games: Correlation and Minimax

ERIC Educational Resources Information Center

A game is presented in which computation by a stepping-stone method is used to solve minimax problems. An additional application of this game is used for finding the Pearson correlation coefficient by non-parametric techniques. The game provides considerable computational practice as well as a motivational problem solving situation. (JP)

Norman, Max C.

1973-01-01

92

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

Lakens, Daniel

2013-01-01

93

During in vitro fertilization-embryo transfer (IVF-ET) treatment, most women require controlled ovarian hyperstimulation (COH). COH with gonadotropins results in an increase in steroid hormonal levels; however, it is unclear what impact these high concentrations of steroid hormones have on cardiac heart function. The purpose of this study was to examine the effect of high levels of estradiol (E2) and progesterone (P) during COH treatment on cardiac function in women undergoing IVF-ET. A total of 34 women with infertility due to tubal or male factors treated with COH and 28 women with normal menstrual cycles who underwent ovulation monitoring only were enrolled in this study. The serum levels of steroid hormones and the parameters of echocardiography at different time points during the natural menstrual cycles of the control group and the corresponding time points during COH treatment of the study group were compared. The independent sample with the t test, the paired sample with t test, ?(2) test, and Pearson correlation analysis were applied. The steroid hormonal levels were significantly different between natural menstrual cycles and COH treatment cycles. Left ventricular end-diastolic volume (LVEDV) reached the highest level on day 7 after oocyte pickup; in contrast, ejection fraction (LVEF) was the lowest level on the same day. On day 16 after ET, E2 and P levels were maintained in the pregnant women in the study group; however, the levels of those hormones returned to those of a natural menstrual cycle in non-pregnant women. The parameters of LVEF and LVEDV significantly correlated with E2 concentrations. High levels of E2 during COH treatment may temporarily affect cardiac function, suggesting that COH intervention is relatively safe; however, a certain level of risk might exist. PMID:23576024

Li, Yiran; Sun, Xiuhua; Zang, Lili; Zhang, Quan; Li, Jichun; Zou, Shuhua

2013-12-01

94

Wanted: guidelines for reporting correlations

NSDL National Science Digital Library

Recently (1ÃÂ3), there have been guidelines published for authors regarding what and how statistics should be reported when describing the differences between groups of observations. There seems to be a paucity of such guidance with respect to describing the correlation between groups of observations. Of particular concern to me is the way in which Pearson product-moment correlations are reported in many journals.

Bartholomew Kay (University of Auckland Sport and Exercise Science)

2009-06-01

95

A comparison of the power of the t test, Mann Kendall and bootstrap tests for trend detection

Monte Carlo simulation is applied to compare the power of the statistical tests: the parametric t test, the non-parametric Mann-Kendall (MK), bootstrap-based slope (BS-slope), and bootstrap-based MK (BS-MK) tests to assess the significance of monotonic (linear and nonlinear) trends. Simulation results indicate that (a) the t test and the BS-slope test, which are slope-based tests, have the same power; (b)

SHENG YUE; PAUL PILON

96

Variable Frequency Bioimpedance Instrumentation D. Tsunami1, J. McNames1, A. Colbert2,3, S. Pearson cancer, impedance of limbs to assess fluid volumes, and respiratory monitoring via chest wall impedance

97

Assessment of correlation between knee notch width index and the three-dimensional notch volume.

This study was done to determine whether there is a correlation between the notch volume and the notch width index (NWI) as measured on the three most frequently used radiographic views: the Holmblad 45 degrees, Holmblad 70 degrees, and Rosenberg view. The notch volume of 20 cadaveric knees was measured using Computed Tomography (CT). The Holmblad 45 degrees, Holmblad 70 degrees, and Rosenberg notch view radiographs were digitally re-created from the CT scans for each specimen, and the NWI was measured by two observers. The Pearson correlation coefficient between the NWI and notch volume was calculated, as well as between the three views. An independent t test was performed to determine the difference in NWI and notch volume between male and female specimens. The reliability for each view was also determined. There was no correlation between the NWI as measured on the Holmblad 45 degrees, Holmblad 70 degrees, or Rosenberg view and the notch volume. All three radiographic views proved reliable, but showed only a moderate correlation with each other. Men had larger notch volumes than women, but there was no difference in NWI. A knee with a small intercondylar notch is often considered an increased risk for ACL rupture. The NWI is a frequently used two-dimensional method to determine notch size. However, in the present study, this index was not positively correlated with the overall volume of the notch. Based on the results of the current study, the authors would advice to use caution when using notch view radiographs in a clinical setting to predict risk of ACL rupture. PMID:20376620

van Eck, Carola F; Martins, Cesar A Q; Lorenz, Stephan G F; Fu, Freddie H; Smolinski, P

2010-09-01

98

Background. Literature data suggest that cells such as mast cells (MCs), are involved in angiogenesis. MCs can stimulate angiogenesis by releasing of several proangiogenic cytokines stored in their cytoplasm. In particular MCs can release tryptase, a potent in vivo and in vitro proangiogenic factor. Nevertheless few data are available concerning the role of MCs positive to tryptase in primary pancreatic cancer angiogenesis. This study analyzed MCs and angiogenesis in primary tumour tissue from patients affected by pancreatic ductal adenocarcinoma (PDAC). Method. A series of 31 PDAC patients with stage T2-3N0-1M0 (by AJCC for Pancreas Cancer Staging 7th Edition) was selected and then underwent surgery. Tumour tissue samples were evaluated by means of immunohistochemistry and image analysis methods in terms of number of MCs positive to tryptase (MCDPT), area occupied by MCs positive to tryptase (MCAPT), microvascular density (MVD), and endothelial area (EA). The above parameters were related to each other and to the main clinicopathological features. Results. A significant correlation between MCDPT, MCAPT, MVD, and EA group was found by Pearson's t-test analysis (r ranged from 0.69 to 0.81; P value ranged from 0.001 to 0.003). No other significant correlation was found. Conclusion. Our pilot data suggest that MCs positive to tryptase may play a role in PDAC angiogenesis and they could be further evaluated as a novel tumour biomarker and as a target of antiangiogenic therapy. PMID:24995015

Sacco, Rosario; Sammarco, Giuseppe; Donato, Giuseppe; Zuccala, Valeria; Luposella, Maria; Patruno, Rosa; Marech, Ilaria; Montemurro, Severino; Zizzo, Nicola; Gadaleta, Cosmo Damiano

2014-01-01

99

NASA Astrophysics Data System (ADS)

This paper presents parameter estimation techniques useful for detecting background changes in a video sequence with extreme foreground activity. A specific application of interest is automated detection of the covert placement of threats (e.g., a briefcase bomb) inside crowded public facilities. We propose that a histogram of pixel intensity acquired from a fixed mounted camera over time for a series of images will be a mixture of two Gaussian functions: the foreground probability distribution function and background probability distribution function. We will use Pearson's Method of Moments to separate the two probability distribution functions. The background function can then be "remembered" and changes in the background can be detected. Subsequent comparisons of background estimates are used to detect changes. Changes are flagged to alert security forces to the presence and location of potential threats. Results are presented that indicate the significant potential for robust parameter estimation techniques as applied to video surveillance.

Jenkins, Colleen; Jordan, Jay; Carlson, Jeff

2007-02-01

100

correlation Measure of Parent/Family Functioning Mean score (SD) r p

Pearson's correlation Measure of Parent/Family Functioning Mean score (SD) r p Global Severity) Â· Affected 69,184 children in 2009. Â· Affects around 20% of girls and 8% of boys. Â· Those who experience CSA

Farritor, Shane

101

Discrete Pearson distributions

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.

Bowman, K.O. [Oak Ridge National Lab., TN (United States); Shenton, L.R. [Georgia Univ., Athens, GA (United States); Kastenbaum, M.A. [Kastenbaum (M.A.), Basye, VA (United States)

1991-11-01

102

We propose a sampling-based Bayesian t test that allows researchers to quantify the statistical evidence in favor of the null\\u000a hypothesis. This Savage—Dickey (SD) t test is inspired by the Jeffreys—Zellner—Siow (JZS) t test recently proposed by Rouder,\\u000a Speckman, Sun, Morey, and Iverson (2009). The SD test retains the key concepts of the JZS test but is applicable to a

Ruud Wetzels; Jeroen G. W. Raaijmakers; Emöke Jakab; Eric-Jan Wagenmakers

2009-01-01

103

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.

Kumar, Ashish; Rana, Vivek; Aggarwal, Abhai; Chandra, Lokesh

2013-01-01

104

Understanding of proteins adaptive to hypersaline environment and identifying them is a challenging task and would help to design stable proteins. Here, we have systematically analyzed the normalized amino acid compositions of 2121 halophilic and 2400 non-halophilic proteins. The results showed that halophilic protein contained more Asp at the expense of Lys, Ile, Cys and Met, fewer small and hydrophobic residues, and showed a large excess of acidic over basic amino acids. Then, we introduce a support vector machine method to discriminate the halophilic and non-halophilic proteins, by using a novel Pearson VII universal function based kernel. In the three validation check methods, it achieved an overall accuracy of 97.7%, 91.7% and 86.9% and outperformed other machine learning algorithms. We also address the influence of protein size on prediction accuracy and found the worse performance for small size proteins might be some significant residues (Cys and Lys) were missing in the proteins. PMID:23764527

Zhang, Guangya; Ge, Huihua

2013-10-01

105

(s): Scott M. Pearson, Monica G. Turner, Linda L. Wallace, William H. Romme Source: Ecological Applications to Ecological Applications. http://www.jstor.org #12;Ecological Applications, 5(3), 1995, pp. 744-755 C) 1995National Laboratory,P.O. Box 2008, Oak Ridge,Tennessee37831-6038 USA LINDA L. WALLACE Departmentof

Turner, Monica G.

106

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.

England, Jr. , J. F.; Salas, J. D.; Jarrett, R. D.

2003-01-01

107

coefficient () = the slope () estimated from a linear least squares fit of y = x + on the same data( , ) = The slope derived using linear least squares (minimising MSE etc..) with regressed on i i x y i i x y x x y y x y x x y y y - - = - - ( )( ) ( ) 22 : cov( , ) = (1) Two points are noteworthy: 1. Eqn (1

Masci, Frank

108

Structural connectivity in human brain has been studied by modeling the statistical dependence between features of cortical regions, such as gray matter thickness. Statistical correlations between gray matter thickness have been mainly used as a metric to study this dependence. In this paper, we propose the use of partial correlations instead of Pearson correlation for inferring the brain structural connectivity

Anand A. Joshi; Shantanu H. Joshi; Ivo D. Dinov; David W. Shattuck; Richard M. Leahy; Arthur W. Toga

2010-01-01

109

Perceived stress in HIV-infected individuals: Physiological and psychological correlates

The purpose of this study was to determine the correlation of perceived stress with selected physiological and psychological factors in an HIV-infected, predominantly African American population and to assess the multivariable effects on perceived stress. The variables that correlated significantly with perceived stress were entered into a backward stepwise regression model. Pearson's r analysis showed significant correlations between perceived stress

G. A. Hand; K. D. Phillips; W. D. Dudgeion

2006-01-01

110

ERIC Educational Resources Information Center

The standard Pearson correlation coefficient is a biased estimator of the true population correlation, ?, when the predictor and the criterion are range restricted. To correct the bias, the correlation corrected for range restriction, r-sub(c), has been recommended, and a standard formula based on asymptotic results for estimating its standard…

Chan, Wai; Chan, Daniel W.-L.

2004-01-01

111

Nonlinear canonical correlation analysis of the tropical Paci#12;c wind stress and sea surface) formulated by a neural network approach was applied to the monthly surface wind stress (WS) and sea surface maximum correlation, i.e. the weight vectors a and b are chosen such that the Pearson correlation coe

Hsieh, William

112

Purpose To evaluate the usefulness of dynamic susceptibility contrast (DSC) enhanced perfusion MR imaging in predicting major genetic alterations in glioblastomas. Materials and Methods Twenty-five patients (M:F?=?13?12, mean age: 52.1±15.2 years) with pathologically proven glioblastoma who underwent DSC MR imaging before surgery were included. On DSC MR imaging, the normalized relative tumor blood volume (nTBV) of the enhancing solid portion of each tumor was calculated by using dedicated software (Nordic TumorEX, NordicNeuroLab, Bergen, Norway) that enabled semi-automatic segmentation for each tumor. Five major glioblastoma genetic alterations (epidermal growth factor receptor (EGFR), phosphatase and tensin homologue (PTEN), Ki-67, O6-methylguanine-DNA methyltransferase (MGMT) and p53) were confirmed by immunohistochemistry and analyzed for correlation with the nTBV of each tumor. Statistical analysis was performed using the unpaired Student t test, ROC (receiver operating characteristic) curve analysis and Pearson correlation analysis. Results The nTBVs of the MGMT methylation-negative group (mean 9.5±7.5) were significantly higher than those of the MGMT methylation-positive group (mean 5.4±1.8) (p?=?.046). In the analysis of EGFR expression-positive group, the nTBVs of the subgroup with loss of PTEN gene expression (mean: 10.3±8.1) were also significantly higher than those of the subgroup without loss of PTEN gene expression (mean: 5.6±2.3) (p?=?.046). Ki-67 labeling index indicated significant positive correlation with the nTBV of the tumor (p?=?.01). Conclusion We found that glioblastomas with aggressive genetic alterations tended to have a high nTBV in the present study. Thus, we believe that DSC-enhanced perfusion MR imaging could be helpful in predicting genetic alterations that are crucial in predicting the prognosis of and selecting tailored treatment for glioblastoma patients. PMID:23977117

Ryoo, Inseon; Choi, Seung Hong; Kim, Ji-Hoon; Sohn, Chul-Ho; Kim, Soo Chin; Shin, Hwa Seon; Yeom, Jeong A.; Jung, Seung Chai; Lee, A. Leum; Yun, Tae Jin; Park, Chul-Kee; Park, Sung-Hye

2013-01-01

113

Validation of a group 24-hour recall method for dietary assessment

data for the corresponding meal were compared via paired t-tests and Pearson's correlation coefficients. Paired t-tests were completed using crude and log[e] transformed data. Results of t-tests indicated no significant differences between means...

Scott, Amanda Renee

2012-06-07

114

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.

Lee, Larissa J. [Harvard Radiation Oncology Program, Brigham and Women's Hospital, Boston, MA (United States); Sadow, Cheryl A. [Department of Radiology, Brigham and Women's Hospital, Boston, MA (United States); Russell, Anthony [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Viswanathan, Akila N., E-mail: aviswanathan@lroc.harvard.ed [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States)

2009-11-01

115

NASA Astrophysics Data System (ADS)

The aromaticity and crystallite parameters in asphalt binders are calculated from data obtained after profile fitting x-ray line spectra using Pearson VII and pseudo-Voigt functions. The results are presented and discussed in terms of the peak profile fit parameters used, peak deconvolution procedure, and differences in calculated values that can arise owing to peak shape and additional peaks present in the pattern. These results have implications concerning the evaluation and performance of asphalt binders used in highways and road applications.

Shirokoff, J.; Lewis, J. Courtenay

2010-10-01

116

NASA Astrophysics Data System (ADS)

X-ray line spectra profile fitting using Pearson VII, pseudo-Voigt and generalized Fermi functions was performed on asphalt binders prior to the calculation of aromaticity and crystallite size parameters. The effects of these functions on the results are presented and discussed in terms of the peak profile fit parameters, the uncertainties in calculated values that can arise owing to peak shape, peak features in the pattern and crystallite size according to the asphalt models (Yen, modified Yen or Yen-Mullins) and theories. Interpretation of these results is important in terms of evaluating the performance of asphalt binders widely used in the application of transportation systems (roads, highways, airports).

Gebresellasie, K.; Shirokoff, J.; Lewis, J. C.

2012-12-01

117

In this study an attempt was made to investigate the relationship between the students theory and practical scores of the basic Science subjects of students of the Kwara State College of Education, Ilorin. The sample consisted of 110 students (28; Chemistry, 17; Physics, 65; Biology). Using the Pearson Product Moment Correlation Coefficient, the Coefficient of Correlation obtained are 0.41, 0.56,

D. O. K. Omole; S. O. Ajayi

118

Fast R Functions for Robust Correlations and Hierarchical Clustering.

Many high-throughput biological data analyses require the calculation of large correlation matrices and/or clustering of a large number of objects. The standard R function for calculating Pearson correlation can handle calculations without missing values efficiently, but is inefficient when applied to data sets with a relatively small number of missing data. We present an implementation of Pearson correlation calculation that can lead to substantial speedup on data with relatively small number of missing entries. Further, we parallelize all calculations and thus achieve further speedup on systems where parallel processing is available. A robust correlation measure, the biweight midcorrelation, is implemented in a similar manner and provides comparable speed. The functions cor and bicor for fast Pearson and biweight midcorrelation, respectively, are part of the updated, freely available R package WGCNA.The hierarchical clustering algorithm implemented in R function hclust is an order n(3) (n is the number of clustered objects) version of a publicly available clustering algorithm (Murtagh 2012). We present the package flashClust that implements the original algorithm which in practice achieves order approximately n(2), leading to substantial time savings when clustering large data sets. PMID:23050260

Langfelder, Peter; Horvath, Steve

2012-03-01

119

NASA Astrophysics Data System (ADS)

Both student's t-test for paired data and the Dorfman- Berbaum-Metz (DBM) method report a P value in comparing ROC curves of competing diagnostic modalities. We empirically compared the P values from the t-test and the DBM method using data of two observer studies involving the lung-nodule detection (15 readers 240 cases) and breast-lesion classification (10 readers 104 cases). We made 596,637 comparisons based on data drawn from different combinations and subsets of the readers and cases. The average difference in the P values was 0.11 and 0.058 in the lung nodule study (of two separate analyses) and 0.0061 in the breast lesion study. The lung nodule study showed, in the analysis that demonstrated statistical significance with the original full dataset, both P<0.05 or both p>0.05 in 83% of the comparisons. The t-test alone reported P<0.05 in 17%, and the DBM method alone reported P<0.05 in 1% of the comparisons. A second analysis of the part of the lung nodule study that did not show statistical significance with the original full dataset found both P<0.05 or both P>0.05 in 99% of the comparisons. The t-test alone reported P<0.05 in 1%, and the DBM method alone reported P<0.05 in less than 1% of the comparisons. The breast lesion study showed both P<0.05 or both P>0.05 in 91% of the comparisons. The t-test alone reported P<0.05 in 5%, and the DBM method alone reported P<0.05 in 4% of the comparisons. These results indicate that the t-test and the DBM method generally report similar P values, but their conclusions regarding statistical significance often differ and the DBM method should be used because it accounts for both reader and case variances.

Jiang, Yulei

2002-04-01

120

A robust measure of correlation between two genes on a microarray

Background The underlying goal of microarray experiments is to identify gene expression patterns across different experimental conditions. Genes that are contained in a particular pathway or that respond similarly to experimental conditions could be co-expressed and show similar patterns of expression on a microarray. Using any of a variety of clustering methods or gene network analyses we can partition genes of interest into groups, clusters, or modules based on measures of similarity. Typically, Pearson correlation is used to measure distance (or similarity) before implementing a clustering algorithm. Pearson correlation is quite susceptible to outliers, however, an unfortunate characteristic when dealing with microarray data (well known to be typically quite noisy.) Results We propose a resistant similarity metric based on Tukey's biweight estimate of multivariate scale and location. The resistant metric is simply the correlation obtained from a resistant covariance matrix of scale. We give results which demonstrate that our correlation metric is much more resistant than the Pearson correlation while being more efficient than other nonparametric measures of correlation (e.g., Spearman correlation.) Additionally, our method gives a systematic gene flagging procedure which is useful when dealing with large amounts of noisy data. Conclusion When dealing with microarray data, which are known to be quite noisy, robust methods should be used. Specifically, robust distances, including the biweight correlation, should be used in clustering and gene network analysis. PMID:17592643

Hardin, Johanna; Mitani, Aya; Hicks, Leanne; VanKoten, Brian

2007-01-01

121

E-learning as an educational approach has been adopted by diverse educational and academic centers worldwide as it facilitates learning in facing the challenges of the new era in education. Considering the significance of virtual education and its growing practice, it is of vital importance to examine its components for promoting and maintaining success. This analytical cross-sectional study was an attempt to determine the relationship between four factors of content, educator, learner and system, and effective e-learning in terms of demographic variables, including age, gender, educational background, and marital status of postgraduate master's students (MSc) studying at virtual faculty of Tehran University of Medical Sciences. The sample was selected by census (n=60); a demographic data gathering tool and a researcher-made questionnaire were used to collect data. The face and content validity of both tools were confirmed and the results were analyzed by descriptive statistics (frequency, percentile, standard deviation and mean) and inferential statistics (independent t-test, Scheffe's test, one-way ANOVA and Pearson correlation test) by using SPSS (V.16). The present study revealed that There was no statistically significant relationship between age and marital status and effective e-learning (P>0.05); whereas, there was a statistically significant difference between gender and educational background with effective e-learning (P<0.05). Knowing the extent to which these factors can influence effective e-learning can help managers and designers to make the right decisions about educational components of e-learning, i.e. content, educator, system and learner and improve them to create a more productive learning environment for learners. PMID:25415821

Golband, Farnoosh; Hosseini, Agha Fatemeh; Mojtahedzadeh, Rita; Mirhosseini, Fakhrossadat; Bigdeli, Shoaleh

2014-11-01

122

Asymmetric correlation matrices: an analysis of financial data

NASA Astrophysics Data System (ADS)

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.

Livan, G.; Rebecchi, L.

2012-06-01

123

Simple Estimation of Hidden Correlation in Repeated Measures

In medical and social studies, it is often desirable to assess the correlation between characteristics of interest that are not directly observable. In such cases, repeated measures are often available, but the correlation between the repeated measures is not the same as that between the true characteristics that are confounded with the measurement errors. The latter is called the hidden correlation. Previously, the problem has been treated by assuming prior knowledge about the measurement errors, or by using relatively complex statistical models, such as the mixed effects models, with no closed-form expression for the estimated hidden correlation. We propose a simple estimator of the hidden correlation that is very much like the Pearson correlation coefficient, with a closed-form expression, under assumptions much weaker than the mixed effects model. Simulation results show that the proposed simple estimator performs similarly as the restricted maximum likelihood (REML) estimator in mixed models, but is computationally much more efficient than REML. Simulation comparison with the Pearson correlation is also made. A real data example is considered. PMID:21997471

Nguyen, Thuan; Jiang, Jiming

2013-01-01

124

Motivation A formidable challenge in the analysis of microarray data is the identification of those genes that exhibit differential expression. The objectives of this research were to examine the utility of simple ANOVA, one sided t tests, natural log transformation, and a generalized experiment wise error rate methodology for analysis of such experiments. As a test case, we analyzed a Affymetrix GeneChip microarray experiment designed to test for the effect of a CHD3 chromatin remodeling factor, PICKLE, and an inhibitor of the plant hormone gibberellin (GA), on the expression of 8256 Arabidopsis thaliana genes. Results The GFWER(k) is defined as the probability of rejecting k or more true null hypothesis at a given p level. Computing probabilities by GFWER(k) was shown to be simple to apply and, depending on the value of k, can greatly increase power. A k value as small as 2 or 3 was concluded to be adequate for large or small experiments respectively. A one sided t-test along with GFWER(2)=.05 identified 43 genes as exhibiting PICKLE-dependent expression. Expression of all 43 genes was re-examined by qRT-PCR, of which 36 (83.7%) were confirmed to exhibit PICKLE-dependent expression. PMID:20016750

Muir, W. M.; Romero-Severson, J.; Rider, S. D.; Simons, A.; Ogas, J.

2009-01-01

125

Mitochondrial Inverted Repeats Strongly Correlate with Lifespan: mtDNA Inversions and Aging

Mitochondrial defects are implicated in aging and in a multitude of age-related diseases, such as cancer, heart failure, Parkinson’s disease, and Huntington’s disease. However, it is still unclear how mitochondrial defects arise under normal physiological conditions. Mitochondrial DNA (mtDNA) deletions caused by direct repeats (DRs) are implicated in the formation of mitochondrial defects, however, mitochondrial DRs show relatively weak (Pearson’s r?=??0.22, p<0.002; Spearman’s ??=??0.12, p?=?0.1) correlation with maximum lifespan (MLS). Here we report a stronger correlation (Pearson’s r?=??0.55, p<10–16; Spearman’s ??=??0.52, p<10–14) between mitochondrial inverted repeats (IRs) and lifespan across 202 species of mammals. We show that, in wild type mice under normal conditions, IRs cause inversions, which arise by replication-dependent mechanism. The inversions accumulate with age in the brain and heart. Our data suggest that IR-mediated inversions are more mutagenic than DR-mediated deletions in mtDNA, and impose stronger constraint on lifespan. Our study identifies IR-induced mitochondrial genome instability during mtDNA replication as a potential cause for mitochondrial defects. PMID:24069185

Yang, Jiang-Nan; Seluanov, Andrei; Gorbunova, Vera

2013-01-01

126

Monte Carlo simulation is applied to compare the power of the statistical tests: the parametric t test, the non-parametric Mann-Kendall (MK), bootstrap-based slope (BS-slope), and bootstrap-based MK (BS-MK) tests to assess the significance of monotonic (linear and nonlinear) trends. Simulation results indicate that (a) the t test and the BS-slope test, which are slope-based tests, have the same power; (b)

Sheng Yue; Paul Pilon

2004-01-01

127

Correlation 43.2 Introduction While medical researchers might be interested in knowing, tests exist which allow us to interpret the meaning of a calculated correlation coefficient. 9 8 6 7 on a random error component say e and we have Y = mx + c + e In some situations, both X and Y are random

Vickers, James

128

NASA Astrophysics Data System (ADS)

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.

Kmetz, Barbara Fotta

2001-07-01

129

Correlation between Pediatric Balance Scale and Functional Test in Children with Cerebral Palsy

[Purpose] To investigate the correlation of functional balance with the functional performance of children with cerebral palsy. [Subjects and Methods] This was a cross-sectional study of children with cerebral palsy with mild to moderate impairment. The children were divided into 3 groups based on motor impairment. The evaluation consisted of the administration of the Pediatric Balance Scale (PBS) and the Pediatric Evaluation Disability Inventory. Correlations between the instruments were determined by calculating Pearson’s correlation coefficients. [Results] In Group 1, a strong positive correlation was found between the PBS and the mobility dimension of the Pediatric Evaluation Disability Inventory (r=0.82), and a moderate correlation was found between the PBS and self-care dimension of the Pediatric Evaluation Disability Inventory (r=0.51). In Group 2, moderate correlations were found between the PBS and both the self-care dimension (r=0.57) and mobility dimension (r=0.41) of the Pediatric Evaluation Disability Inventory. In Group 3, the PBS was weakly correlated with the self-care dimension (r=0.11) and moderately correlated with the mobility dimension (r=0.55). [Conclusion] The PBS proved to be a good auxiliary tool for the evaluation of functional performance with regard to mobility, but cannot be considered a predictor of function in children with cerebral palsy. PMID:25013281

Duarte, Natalia de A. C.; Grecco, Luanda Andre Collange; Franco, Renata Calhes; Zanon, Nelci; Oliveira, Claudia Santos

2014-01-01

130

Application of a correlation correction factor in a microarray cross-platform reproducibility study

Background Recent research examining cross-platform correlation of gene expression intensities has yielded mixed results. In this study, we demonstrate use of a correction factor for estimating cross-platform correlations. Results In this paper, three technical replicate microarrays were hybridized to each of three platforms. The three platforms were then analyzed to assess both intra- and cross-platform reproducibility. We present various methods for examining intra-platform reproducibility. We also examine cross-platform reproducibility using Pearson's correlation. Additionally, we previously developed a correction factor for Pearson's correlation which is applicable when X and Y are measured with error. Herein we demonstrate that correcting for measurement error by estimating the "disattenuated" correlation substantially improves cross-platform correlations. Conclusion When estimating cross-platform correlation, it is essential to thoroughly evaluate intra-platform reproducibility as a first step. In addition, since measurement error is present in microarray gene expression data, methods to correct for attenuation are useful in decreasing the bias in cross-platform correlation estimates. PMID:18005444

Archer, Kellie J; Dumur, Catherine I; Taylor, G Scott; Chaplin, Michael D; Guiseppi-Elie, Anthony; Grant, Geraldine; Ferreira-Gonzalez, Andrea; Garrett, Carleton T

2007-01-01

131

Correlations between blood glucose and breath components from portable gas sensors and PTR-TOF-MS.

Acetone is one of the most abundant volatile compounds in the human breath and might be important for monitoring diabetic patients. Here, a portable acetone sensor consisting of flame-made, nanostructured, Si-doped WO3 sensing films was used to analyse the end tidal fraction of the breath (collected in Tedlar bags) from eight healthy volunteers after overnight fasting (morning) and after lunch (afternoon). After breath sampling, the gaseous components were also analysed by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS), and each person's blood glucose level was measured. The portable sensor accurately detected the presence of acetone with fast response/recovery times (<12 s) and a high signal-to-noise ratio. Statistical analysis of the relationship between the PTR-TOF-MS measurements of breath gases (e.g., acetone, isoprene, ethanol and methanol), sensor response and the blood glucose level was performed for both sampling periods. The best correlations were found after overnight fasting (morning): in particular, between blood glucose level and breath acetone (Pearson's 0.98 and Spearman's 0.93). Whereas the portable sensor response correlated best with the blood glucose (Pearson's 0.96 and Spearman's 0.81) and breath acetone (Pearson's 0.92 and Spearman's 0.69). PMID:23959908

Righettoni, M; Schmid, A; Amann, A; Pratsinis, S E

2013-09-01

132

To evaluate the construct validity (convergent and divergent) of Sivik Psycho Somaticism test (SPS) and test of Operationality (OPER), Pearson correlation coefficients between SPS scales and subscales and Karolinska Scheme of Personality (KSP) were calculated. Seventy-eight healthy individuals and 196 psychosomatic patients completed the SPS and OPER tests and KSP. The results show that the SPS and OPER subscales are significantly correlated to most KSP subscales. The correlations were higher for the psychosomatic group than for the normal population. The results confirm the validity of the SPS and OPER constructs. PMID:10485606

Sivik, T; Delimar, N; Schoenfeld, R

1999-01-01

133

Correlation of the Y-Balance Test with Lower-limb Strength of Adult Women

[Purpose] The purpose of this study was to elucidate the relationship between Y-balance test (YBT) distance and the lower-limb strength of adult women. [Subjects] Forty women aged 45 to 80?years volunteered for this study. [Methods] The participants were tested for maximal muscle strength of the lower limbs (hip extensors, hip flexors, hip abductors, knee extensors, knee flexors, and ankle dorsiflexors) and YBT distances in the anterior, posteromedial, and posterolateral directions. Pearson’s correlation coefficient was used to quantify the linear relationships between YBT distances and lower-limb strength. [Results] Hip extensor and knee flexor strength were positively correlated with YBT anterior distance. Hip extensor, hip abductor, and knee flexor strength were positively correlated with the YBT posteromedial distance. Hip extensor and knee flexor strength were positively correlated with YBT posterolateral distance. [Conclusion] There was a weak correlation between lower-limb strength (hip extensors, hip abductors, and knee flexors) and dynamic postural control as measured by the YBT. PMID:24926122

Lee, Dong-Kyu; Kim, Gyoung-Mo; Ha, Sung-Min; Oh, Jae-Seop

2014-01-01

134

Copyright 2012 Pearson Education, Inc. 1. Introduction

are the following. The student Â· can see in easy fashion the behavior of solutions by means of graphs in the form, mathematical epidemiolo- gy, special functions, electrical circuits, and athletics. A brief overview of each

Ding, Wandi

135

Gates, Pearson Partner on Common Core

ERIC Educational Resources Information Center

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…

Gewertz, Catherine

2011-01-01

136

Pearson’s correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab(R) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand. PMID:23335907

Pernet, Cyril R.; Wilcox, Rand; Rousselet, Guillaume A.

2012-01-01

137

Substance Abuse Counselors and Moral Reasoning: Hypothetical and Authentic Dilemmas

ERIC Educational Resources Information Center

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…

Sias, Shari M.

2009-01-01

138

Emotional structure and commitment: implications for health care management

Purpose – This paper aims to determine if the emotional structure of direct healthcare workers was related to their commitment to the organization. Design\\/methodology\\/approach – A total of 105 direct healthcare workers completed self-report surveys to determine their emotional intelligence, emotional coping ability, and affective organizational commitment. Pearson Product Moment Correlation and independent sample t tests were used to analyze

John Humphreys; Bill Brunsen; Dale Davis

2005-01-01

139

ERIC Educational Resources Information Center

The purpose of this study is to examine the ICT usage and academic achievement of Turkish students in PISA 2006 data. The sample of the study included 4942 students from 160 schools. Frequencies, independent samples t-tests, ANOVAs, pearson correlation coefficients, exploratory factor analysis, and regression analysis were used. A high percentage…

Aypay, Ahmet

2010-01-01

140

This study examines a sample of 35 male children and adolescents involved with a northeastern district of the Georgia Department of Juvenile Justice. Subjects who participated in wilderness adventure therapy programs are compared to those who participated in group home programs. The study examines the rates of recidivism among the subjects within each group. Pearson correlations, t-tests, and ANOVA were

Christopher D. Jones; Laura A. Lowe; Edwin A. Risler

2004-01-01

141

Anthropometric and Behavioral Measures Related to Mindfulness in College Students

Objective: To determine whether mindfulness is associated with physical and behavioral measures in first semester college students. Participants: Male and female first year college students (n = 75) from the University of Rhode Island. Methods: Height, weight, waist circumference (WC), and blood pressure were assessed and online questionnaires were completed. Independent t tests and Pearson correlations were utilized for analysis.

Sarah Grinnell; Geoffrey Greene; Kathleen Melanson; Bryan Blissmer; Ingrid E. Lofgren

2011-01-01

142

Materials and Methods: Plain radiographs of 248 females and 298 males between 11 and 22 years of age were taken. Paired sample t-tests, Pearson correlation coefficients, and linear regression were used to determine the differences and model the relationships between mean skeletal (bone) age (BA) and mean chronological age (CA), using SPSS 11.5 statistical software. Results: In all cases, the

Erhan BÜKEN; Alp Alper; Burhan YAZICI; Zerrin ERKOL; Atilla Senih MAYDA

143

An Investigation of Aggression and Interpersonal Problem Solving in Adolescents

The purpose of this study was to investigate agression and interpersonal problem solving in terms of gender, and to investigate relationship between agression and interpersonal problem solving of adolescents. The study was in survey model and participants were 483 (180 female and 303 male) adolescents. T test, Pearson product-moment correlation coefficients and multiple regression analysis were determined. In study it

Erdal HAMARTA; Emel ARSLAN; Yeliz SAYGIN

144

Correlation Between University Students' Kinematic Achievement and Learning Styles

NASA Astrophysics Data System (ADS)

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.

Çirkino?lu, A. G.; Dem&ircidot, N.

2007-04-01

145

Diversity of the vaginal microbiome correlates with preterm birth.

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 ± 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

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; Giudice, Linda C

2014-01-01

146

The standard Pearson correlation coefficient is a biased estimator of the true population correlation, rho, when the predictor and the criterion are range restricted. To correct the bias, the correlation corrected for range restriction, rc, has been recommended, and a standard formula based on asymptotic results for estimating its standard error is also available. In the present study, the bootstrap standard-error estimate is proposed as an alternative. Monte Carlo simulation studies involving both normal and nonnormal data were conducted to examine the empirical performance of the proposed procedure under different levels of rho, selection ratio, sample size, and truncation types. Results indicated that, with normal data, the bootstrap standard-error estimate is more accurate than the traditional estimate, particularly with small sample size. With nonnormal data, performance of both estimates depends critically on the distribution type. Furthermore, the bootstrap bias-corrected and accelerated interval consistently provided the most accurate coverage probability for rho. PMID:15355154

Chan, Wai; Chan, Daniel W-L

2004-09-01

147

Quantized correlation coefficient for measuring reproducibility of ChIP-chip data

Background Chromatin immunoprecipitation followed by microarray hybridization (ChIP-chip) is used to study protein-DNA interactions and histone modifications on a genome-scale. To ensure data quality, these experiments are usually performed in replicates, and a correlation coefficient between replicates is used often to assess reproducibility. However, the correlation coefficient can be misleading because it is affected not only by the reproducibility of the signal but also by the amount of binding signal present in the data. Results We develop the Quantized correlation coefficient (QCC) that is much less dependent on the amount of signal. This involves discretization of data into set of quantiles (quantization), a merging procedure to group the background probes, and recalculation of the Pearson correlation coefficient. This procedure reduces the influence of the background noise on the statistic, which then properly focuses more on the reproducibility of the signal. The performance of this procedure is tested in both simulated and real ChIP-chip data. For replicates with different levels of enrichment over background and coverage, we find that QCC reflects reproducibility more accurately and is more robust than the standard Pearson or Spearman correlation coefficients. The quantization and the merging procedure can also suggest a proper quantile threshold for separating signal from background for further analysis. Conclusions To measure reproducibility of ChIP-chip data correctly, a correlation coefficient that is robust to the amount of signal present should be used. QCC is one such measure. The QCC statistic can also be applied in a variety of other contexts for measuring reproducibility, including analysis of array CGH data for DNA copy number and gene expression data. PMID:20663215

2010-01-01

148

A STAR TOP ASTRO WEB SITES SHEDDING LIGHT ON DARK SKIES: Â· Build a "Dark Meter" Â· New Dark-Sky Rating NEW 102-MM TELESCOPE WATCH A PLANET BLOT OUT A STAR TOP ASTRO WEB SITES SHEDDING LIGHT ON DARK SKIES: Â· Build a "Dark Meter" Â· New Dark-Sky Rating Scale AURIGA'S SPARKLING STAR CLUSTERS NEW PUBLIC OBSERVATORY

Schrijver, Karel

149

Correlation in business networks

NASA Astrophysics Data System (ADS)

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.

Souma, Wataru; Aoyama, Hideaki; Fujiwara, Yoshi; Ikeda, Yuichi; Iyetomi, Hiroshi; Kaizoji, Taisei

2006-10-01

150

The Nambu–Gorkov generalized Hartree–Fock theory of superconductivity is further generalized to treat simultaneously two kinds of correlations: the correlations that lead to superconductivity, as well as the correlations that produce the pseudogap in the normal state. The treatment of these simultaneous double correlations is done by enlarging the dimension of the propagator and self-energy matrices, from two to four. The

Moshe Dayan

2004-01-01

151

Strongly correlated electron systems

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

Siddharth S Saxena; P B Littlewood

2012-01-01

152

Reverse Correlation in Neurophysiology

ERIC Educational Resources Information Center

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…

Ringach, Dario; Shapley, Robert

2004-01-01

153

Probabilistic Alert Correlation

With the growing deployment of host and network intrusion detection systems, managing reports from these systems becomes critically important. We present a probabilistic approach to alert correlation, extending ideas from multisensor data fusion. Features used for alert correlation are based on alert content that anticipates evolving IETF standards. The probabilistic approach provides a unified mathematical framework for correlating alerts that

Alfonso Valdes; Keith Skinner

2001-01-01

154

Degree Correlations in Directed Scale-Free Networks

Scale-free networks, in which the distribution of the degrees obeys a power-law, are ubiquitous in the study of complex systems. One basic network property that relates to the structure of the links found is the degree assortativity, which is a measure of the correlation between the degrees of the nodes at the end of the links. Degree correlations are known to affect both the structure of a network and the dynamics of the processes supported thereon, including the resilience to damage, the spread of information and epidemics, and the efficiency of defence mechanisms. Nonetheless, while many studies focus on undirected scale-free networks, the interactions in real-world systems often have a directionality. Here, we investigate the dependence of the degree correlations on the power-law exponents in directed scale-free networks. To perform our study, we consider the problem of building directed networks with a prescribed degree distribution, providing a method for proper generation of power-law-distributed directed degree sequences. Applying this new method, we perform extensive numerical simulations, generating ensembles of directed scale-free networks with exponents between 2 and 3, and measuring ensemble averages of the Pearson correlation coefficients. Our results show that scale-free networks are on average uncorrelated across directed links for three of the four possible degree-degree correlations, namely in-degree to in-degree, in-degree to out-degree, and out-degree to out-degree. However, they exhibit anticorrelation between the number of outgoing connections and the number of incoming ones. The findings are consistent with an entropic origin for the observed disassortativity in biological and technological networks. PMID:25310101

Williams, Oliver; Del Genio, Charo I.

2014-01-01

155

To permit new epidemiologic studies of the effects of dioxin on humans in Vietnam, we evaluated a model for quantifying exposure to Agent Orange (exposure index) based on the residential histories of 27 Vietnamese subjects and on information about spraying from the U.S. Army records (Herbs Tape) and compared this index to the dioxin levels measured in the subjects' adipose tissue. The mean dioxin level was 7.8 ppt, and dioxin and furan isomer profiles were similar to those already reported in industrialized countries. In addition, there was a highly significant correlation between the levels of almost all the isomers, whatever their degree of chlorination. For the group of 27 subjects, we found a Pearson correlation coefficient of 0.36 (P = 0.07) between the dioxin levels and the exposure index after log-transformation of both variables. When the analysis was restricted to the 22 subjects with a positive exposure index, the Pearson correlation coefficient rose to 0.50 (P = 0.02). We conclude that despite the limitations and power conditions of the study, this result is encouraging because it will be useful for future epidemiologic studies in Vietnam. PMID:8187739

Verger, P; Cordier, S; Thuy, L T; Bard, D; Dai, L C; Phiet, P H; Gonnord, M F; Abenhaim, L

1994-05-01

156

Time integrating acoustooptic correlator.

This paper describes an acoustooptic technique for achieving signal correlation with a time-bandwidth product of 10(6)-10(8), using existing devices. One signal is used to intensity modulate a light beam that illuminates an acoustic cell. The other signal appears in the cell as a traveling wave and is Schlieren imaged onto a detector array. The detected image intensity is integrated in time, achieving the desired correlation function. Since the correlation integration is performed in time rather than space, the time-bandwidth limitations of earlier acoustooptic correlators are greatly reduced. Experimental procedures for implementation of this technique are discussed and results shown. PMID:20155190

Sprague, R A; Koliopoulos, C L

1976-01-01

157

Fuzzy correlation analysis with realization

NASA Astrophysics Data System (ADS)

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.

Tang, Yue Y.; Fan, Xinrui; Zheng, Ying N.

1998-10-01

158

Correlating Heart Rate and Perceived Exertion during Aerobic Exercise in Alzheimer's Disease

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

Yu, Fang; Bil, Kristin

2010-01-01

159

Computational correlates of consciousness

Over the past few years numerous proposals have appeared that attempt to characterize consciousness in terms of what could be called its computational correlates: Principles of information processing with which to characterize the differences between conscious and unconscious processing. Proposed computational correlates include architectural specialization (such as the involvement of specific regions of the brain in conscious processing), properties of

Axel Cleeremans

2005-01-01

160

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

Nosrati, R; Owlia, P; Saderi, H; Olamaee, M; Rasooli, I; Akhavian, Tehrani A

2012-01-01

161

Hadronic Correlations and Fluctuations

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.

Koch, Volker

2008-10-09

162

CARMA Correlator Graphical Setup

CARMA Correlator Graphical Setup (CGS) is a Java tool to help users of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) plan observations. It allows users to visualize the correlator bands overlaid on frequency space and view spectral lines within each band. Bands can be click-dragged to anywhere in frequency and can have their properties (e.g., bandwidth, quantization level,

D. We; B. Shaya; M. W. Pound

2011-01-01

163

Glueball correlators as holograms

We investigate the dynamical content of both hard- and soft-wall approximations to holographic QCD by deriving the corresponding glueball correlation functions and by confronting them with a variety of QCD results. We further calculate the glueball decay constants in both holographic duals, discuss emerging limitations and improvement strategies, and comment on a recent attempt to generalize the glueball correlator in the soft-wall background.

Forkel, Hilmar

2008-01-01

164

Glueball correlators as holograms

We investigate the dynamical content of both hard- and soft-wall approximations to holographic QCD by deriving the corresponding glueball correlation functions and by confronting them with a variety of QCD results. We further calculate the glueball decay constants in both holographic duals, discuss emerging limitations and improvement strategies, and comment on a recent attempt to generalize the glueball correlator in the soft-wall background.

Hilmar Forkel

2008-08-03

165

CARMA Correlator Graphical Setup

NASA Astrophysics Data System (ADS)

CARMA Correlator Graphical Setup (CGS) is a Java tool to help users of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) plan observations. It allows users to visualize the correlator bands overlaid on frequency space and view spectral lines within each band. Bands can be click-dragged to anywhere in frequency and can have their properties (e.g., bandwidth, quantization level, rest frequency) changed interactively. Spectral lines can be filtered from the view by expected line strength to reduce visual clutter. Once the user is happy with the setup, a button click generates the Python commands needed to configure the correlator within the observing script. CGS can also read Python configurations from an observing script and reproduce the correlator setup that was used. Because the correlator hardware description is defined in an XML file, the tool can be rapidly reconfigured for changing hardware. This has been quite useful as CARMA has recently commissioned a new correlator. The tool was written in Java by high school summer interns working in UMD's Laboratory for Millimeter Astronomy and has become an essential planning tool for CARMA PIs.

Wu, D.; Shaya, B.; Pound, M. W.

2011-07-01

166

Background Biopterins have a crucial role in the function of nitric oxide synthase, uncoupling of the enzyme leads to endothelial dysfunction and vascular damage, The aim of this study was to evaluate the relationship between the levels of biopterins with carotid intima-media thickness (CIMT) in hypertensive type-2 diabetic patients. Methods We studied 30 hypertensive type-2 diabetic patients and 30 normotensive non-diabetic age-matched subjects, in whom biopterins levels were measured by reverse phase high performance liquid chromatography with fluorescence detection. Additionally, the CIMT of both the common and internal carotid arteries was measured. The levels of biopterins and CIMT were correlated using the Pearson correlation coefficient test. Results We did not find a significantly correlation between biopterins levels and CIMT. However, we found a significantly inverse correlation between the BH4/BH2 ratio and the CIMT in patients (r?=?-0.54, p?correlated significantly and independently with the BH4/BH2 ratio. Conclusion Our results suggest that the BH4/BH2 ratio seems to be a better marker of vascular disease than biopterin levels. PMID:24393252

2014-01-01

167

Strongly correlated materials.

Strongly correlated materials are profoundly affected by the repulsive electron-electron interaction. This stands in contrast to many commonly used materials such as silicon and aluminum, whose properties are comparatively unaffected by the Coulomb repulsion. Correlated materials often have remarkable properties and transitions between distinct, competing phases with dramatically different electronic and magnetic orders. These rich phenomena are fascinating from the basic science perspective and offer possibilities for technological applications. This article looks at these materials through the lens of research performed at Rice University. Topics examined include: Quantum phase transitions and quantum criticality in "heavy fermion" materials and the iron pnictide high temperature superconductors; computational ab initio methods to examine strongly correlated materials and their interface with analytical theory techniques; layered dichalcogenides as example correlated materials with rich phases (charge density waves, superconductivity, hard ferromagnetism) that may be tuned by composition, pressure, and magnetic field; and nanostructure methods applied to the correlated oxides VO? and Fe?O?, where metal-insulator transitions can be manipulated by doping at the nanoscale or driving the system out of equilibrium. We conclude with a discussion of the exciting prospects for this class of materials. PMID:22893361

Morosan, Emilia; Natelson, Douglas; Nevidomskyy, Andriy H; Si, Qimiao

2012-09-18

168

Terrain correlation suitability

NASA Astrophysics Data System (ADS)

Terrain-aided navigation (TAN), also referred to as terrain correlation, is a technique that has proven to be highly successful as a navigational aid for autonomous, unmanned guided missiles. Qualitatively speaking, the effectiveness of terrain correlation is a function of signal- to-noise (S/N) ratio. The signal is equivalent to terrain roughness, while the noise is the combination of reference map errors, radar altimeter errors, and INS altitude errors. However, it is not practical to use only a single parameter, such as S/N, to define the suitability of terrain correlation. This paper discusses the shortcomings of the conventional single-parameter approach to the terrain contour matching algorithm (TERCOM) used in cruise missile guidance systems scene selection. A more comprehensive technique is then presented that analyzes the terrain correlation suitability based on a Monte Carlo simulation technique. A figure-of-merit (FOM) for terrain correlation suitability, computed from sample statistics, is introduced and simulation results are provided to illustrate the feasibility of using a multi-parameter FOM technique. The preliminary results indicate that the proposed approach could provide a cost effective enhancement to the TAN-based mission planning process.

Tang, Wang; McClintock, Robert L.

1994-07-01

169

Nonlocality of quantum correlations

We show that only those composite quantum systems possessing nonvanishing quantum correlations have the property that any nontrivial local unitary evolution changes their global state. This type of nonlocality occurs also for states that do not violate a Bell inequality, such as, for instance, Werner states with a low degree of entanglement. We derive the exact relation between the global state change induced by local unitary evolutions and the amount of quantum correlations. We prove that the minimal change coincides with the geometric measure of discord, thus providing the latter with an operational interpretation in terms of the capability of a local unitary dynamics to modify a global state. We establish rigorously that Werner states are the maximally quantum correlated two-qubit states, and thus are the ones that maximize this novel type of nonlocality.

Streltsov, A; Roga, W; Bruß, D; Illuminati, F

2012-01-01

170

Neuroanatomical Correlates of Intelligence

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

Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.

2009-01-01

171

NSDL National Science Digital Library

This webpage will be helpful for students learning to analyze data and create scatter plots. Specifically, these examples demonstrate how to determine correlations, or relationships, between sets of data. The slope of the line created by the data will show if there is a positive, negative, or no correlation between the sets of data. At the bottom of the page, a link is included for students who would like to learn how to create scatter plots with a graphing calculator. These examples are explained clearly and include useful graphics.

Roberts, Donna

2012-01-01

172

Correlation ion mobility spectroscopy

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.

Pfeifer, Kent B. (Los Lunas, NM); Rohde, Steven B. (Corrales, NM)

2008-08-26

173

Comparing Dependent Correlations

In a recent article in The Journal of General Psychology, J. B. Hittner, K. May, and N. C. Silver (2003) described their investigation of several methods for comparing dependent correlations and found that all can be unsatisfactory, in terms of Type I errors, even with a sample size of 300. More precisely, when researchers test at the .05 level, the

Rand R. Wilcox; Tian Tian

2008-01-01

174

ERIC Educational Resources Information Center

As part of a continuing series of research studies on stress in schools, this study examined the construct validity of peripheral temperature at the fingertips as a measure of school stress. Measurements were made in classes selected at random from 11 volunteer schools in South Carolina. Three types of correlational studies were undertaken: (1)…

Matthews, Doris B.

175

Transforming convolution and correlation

NASA Astrophysics Data System (ADS)

We give an explicit expression for the transform of a signal in an arbitrary representation which has first been filtered in another representation. Using this formula we connect the work of Cohen for obtaining convolution and correlation theorems in arbitrary representations with the work of Lindsey and Suter for partitioning the space of integral transforms.

Cohen, Leon; Lindsey, Alan R.; Suter, Bruce W.

2001-12-01

176

Jackknifing Disattenuated Correlations

ERIC Educational Resources Information Center

The utility of the jackknife for constructing confidence intervals and testing hypotheses about the disattenuated correlation is evaluated for small samples. Results of computer simulations support the claim that the jackknife can be used to construct confidence intervals but has limited utility for testing hypotheses about the disattenuated…

Rogers, W. Todd

1976-01-01

177

We present a new approach to the calculation of first passage statistics for correlated random walks on one-dimensional discrete systems. The processes may be non-Markovian and also nonstationary. A number of examples are used to demonstrate the theory.

de la Selva, S.M.T.; Lindenberg, K.; West, B.J.

1988-10-01

178

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

2012-01-01

179

Background To evaluate a potential correlation of the maximum standard uptake value (SUVmax) and the minimum apparent diffusion coefficient (ADCmin) in primary and recurrent cervical cancer based on integrated PET/MRI examinations. Methods 19 consecutive patients (mean age 51.6 years; range 30–72 years) with histopathologically confirmed primary cervical cancer (n?=?9) or suspected tumor recurrence (n?=?10) were prospectively enrolled for an integrated PET/MRI examination. Two radiologists performed a consensus reading in random order, using a dedicated post-processing software. Polygonal regions of interest (ROI) covering the entire tumor lesions were drawn into PET/MR images to assess SUVmax and into ADC parameter maps to determine ADCmin values. Pearson’s correlation coefficients were calculated to assess a potential correlation between the mean values of ADCmin and SUVmax. Results In 15 out of 19 patients cervical cancer lesions (n?=?12) or lymph node metastases (n?=?42) were detected. Mean SUVmax (12.5±6.5) and ADCmin (644.5±179.7×10?5 mm2/s) values for all assessed tumor lesions showed a significant but weak inverse correlation (R?=??0.342, p<0.05). When subdivided in primary and recurrent tumors, primary tumors and associated primary lymph node metastases revealed a significant and strong inverse correlation between SUVmax and ADCmin (R?=??0.692, p<0.001), whereas recurrent cancer lesions did not show a significant correlation. Conclusions These initial results of this emerging hybrid imaging technique demonstrate the high diagnostic potential of simultaneous PET/MR imaging for the assessment of functional biomarkers, revealing a significant and strong correlation of tumor metabolism and higher cellularity in cervical cancer lesions. PMID:24804676

Grueneisen, Johannes; Beiderwellen, Karsten; Heusch, Philipp; Buderath, Paul; Aktas, Bahriye; Gratz, Marcel; Forsting, Michael; Lauenstein, Thomas; Ruhlmann, Verena; Umutlu, Lale

2014-01-01

180

Stature and gender determination and their correlation using odontometry and skull anthropometry

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

Gupta, Amit; Kumar, Kiran; Shetty, Devi Charan; Wadhwan, Vijay; Jain, Anshi; Khanna, Kaveri Surya

2014-01-01

181

Diffusion tensor tractography in hypothyroidism and its correlation with memory function.

Diffusion tensor tractography (DTT) was performed to determine the microstructural changes in the white matter fibre tracts of hypothyroid patients compared to controls and to correlate these changes with memory dysfunction scores. DTT and Postgraduate Institute Memory Scale test were performed in eight hypothyroid patients and eight healthy controls. Diffusion tensor imaging (DTI) measures [fractional anisotropy (FA) and mean diffusivity (MD)] from all of the major cerebral tracts were calculated and a comparison was made between the patient group and controls. Pearson's correlation was performed between Memory Dysfunction score and DTI measures. Significant changes in DTI measures were observed in various white matter fibre tracts in hypothyroid patients compared to controls. In hypothyroid patients, an inverse correlation of Memory Dysfunction score with FA was observed in the right and left inferior fronto-occipital fasciculus, whereas a positive correlation with MD was observed in the right anterior thalamic radiation among all white matter tracts. These findings suggest that microstructural changes in white matter fibres may contribute to the underlying dysfunction in memory in hypothyroid patients. PMID:25131823

Singh, S; Trivedi, R; Singh, K; Kumar, P; Shankar, L R; Khushu, S

2014-11-01

182

NSDL National Science Digital Library

The purpose of this exercise is to introduce students to how simple relative age correlation principles can be used to reliable determine the relative ages of rock units and other geologic features. Students will apply the principles of original horizontality, superposition, cross-cutting relationships and inclusion to determine the relative ages of sedimentary rocks, igneous rocks and metamorphic rocks, as well as unconformities and faults.

Daley, Gwen

183

Propensities, correlations, and metaphysics

NASA Astrophysics Data System (ADS)

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.

Redhead, Michael

1992-03-01

184

Variable angle correlation spectroscopy

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.

Lee, Y.K. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley Lab., CA (United States). Chemical Biodynamics Div.

1994-05-01

185

Correcting Correlation Function Measurements

Correlation functions measured as a function of $\\Delta \\eta, \\Delta \\phi$ have emerged as a powerful tool to study the dynamics of particle production in nuclear collisions at high energy. They are however subject, like any other observables, to instrumental effects which must be properly accounted for to extract meaningful physics results. We compare the merits of several techniques used towards measurement of these correlation functions in nuclear collisions. We discuss and distinguish the effects of finite acceptance, and detection efficiency that may vary with collision parameters such as the position of the event in the detector and the instantaneous luminosity of the beam. We focus in particular on instrumental effects which break the factorization of the particle pair detection efficiency, and describe a technique to recover the robustness of correlation observables. We finally introduce a multi-dimensional weight method to correct for efficiencies that vary simultaneously with particle pseudo rapidity, azimuthal angle, transverse momentum, and the collision vertex position. The method can be generalized to account for any number of "event variables" that may break the factorability of the pair efficiency.

Shantam Ravan; Prabhat Pujahari; Sidharth Prasad; Claude A. Pruneau

2013-11-15

186

This study investigates how workers' gender, work experience, designated division, and appointment affect (i) their perception of information technology (IT) within the organisation, (ii) their self-perceived capacity in knowledge management (KM), and (iii) their perception of organisational performance (OP). Furthermore, the study also examines the correlation among the above three dimensions by using t-test, one-way Analysis of Variance (ANOVA), Pearson

Yen-Ku Kuo; Kung-Don Ye

2010-01-01

187

Bootstrapped Deattenuated Correlation: Nonnormal Distributions

ERIC Educational Resources Information Center

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…

Padilla, Miguel A.; Veprinsky, Anna

2014-01-01

188

Extremely Correlated Fermi Liquids

We present the theory of an extremely correlated Fermi liquid (ECFL) with $U\\to \\infty$. This liquid has an underlying Fermi liquid (FL) Greens function that is further caparisoned. The theory leads to two parallel hierarchies of equations that permit iterative approximations in a certain parameter. Preliminary results for the spectral functions display a broad background and a distinct $T$ dependent left skew. An important energy scale $\\Delta(\\vec{k},x)$ emerges as the average inelasticity of the FL Greens function, and influences the photoemission spectra profoundly. A duality is identified wherein an apparent loss of coherence of the ECFL results from an excessively sharp FL.

B. Sriram Shastry

2011-02-14

189

NASA Technical Reports Server (NTRS)

The objectives of NASA's Living With a Star (LWS) Radiation Belt Storm Probe (RBSP) mission are: (1) Which physical processes produce radiation belt enhancement events? (2) What are the dominant mechanisms for relativistic electron loss? (3) How do ring current and other geomagnetic processes affect radiation belt behavior? Although a stand-alone mission, RBSP will benefit from correlative studies with observations made by other spacecraft and ground-based observatories. In this presentation, we describe the broad range of such studies as a function of RBSP mission phase, pointing to the unique contributions of both the RBSP mission and the other observatories.

Sibeck, D. G.

2012-01-01

190

Confinement from correlation functions

NASA Astrophysics Data System (ADS)

We compute the Polyakov loop potential in Yang-Mills theory from the fully dressed primitively divergent correlation functions only. This is done in a variety of functional approaches ranging from functional renormalization group equations over Dyson-Schwinger equations to two-particle irreducible functionals. We present a confinement criterion that links the infrared behavior of propagators and vertices to the Polyakov loop expectation value. The present work extends the works of [J. Braun , Phys. Lett. B 684, 262 (2010)PYLBAJ0370-2693; F. Marhauser and J. M. Pawlowski, arXiv:0812.1144; J. Braun , Eur. Phys. J. C 70, 689 (2010)EPCFFB1434-6044] to general functional methods and sharpens the confinement criterion presented there. The computations are based on the thermal correlation functions in the Landau gauge calculated in [L. Fister and J. M. Pawlowski, arXiv:1112.5440; L. Fister and J. M. Pawlowski, arXiv:1112.5429; L. Fister, Ph.D. thesis, Heidelberg University, 2012].

Fister, Leonard; Pawlowski, Jan M.

2013-08-01

191

Possible correlation of selenoprotein w with inflammation factors in chicken skeletal muscles.

The aim of the present study was to investigate the possible correlation of selenoprotein W (SelW) with inflammatory injury induced by dietary selenium (Se) deficiency in chicken. One-day-old male chickens were fed either a commercial diet or a Se-deficient diet for 55 days. Then, the expression levels of SelW messenger RNA (mRNA) and inflammation-related genes (NF-?B, TNF-?, iNOS, COX-2, and PTGES) in chicken skeletal muscles (wing muscle, pectoral muscle, and thigh muscle) were determined at 15, 25, 35, 45, and 55 days old, respectively. In addition, the correlation between SelW mRNA expression and inflammation-related genes were assessed. The results showed that dietary Se deficiency reduced the mRNA expression of SelW in chicken wing, pectorals, and thigh muscles. In contrast, Se deficiency increased the mRNA expression levels of inflammation-related genes in chicken skeletal muscle tissues at different time points. The Pearson's correlation coefficients showed that the mRNA expression levels of inflammation-related genes were significantly negative related to SelW (p?

Wu, Qiong; Yao, Hai-Dong; Tan, Si-Ran; Zhang, Zi-Wei; Zhu, Yao-Hong; Xu, Shiwen

2014-11-01

192

Background: Empathy is a multidimensional construct referring to the capacity to understand and share the emotional and affective states of another person. Cerebral ?-aminobutyric acid (GABA)-ergic levels are associated with a variety of neurological and psychiatric disorders. However, the role of the GABA system in different dimensions of empathy has not been investigated. Materials and Methods: Thirty-two right-handed healthy volunteers took part in this study. We used proton magnetic resonance spectroscopy to determine GABA concentrations in the anterior insula (AI) and the anterior cingulate cortex (ACC) and to examine the relationship between the GABA concentrations and the subcomponents of empathy evaluated by the Interpersonal Reactivity Index (IRI). Result: Pearson correlation analyses (two-tailed) showed that AI GABA was significantly associated with the empathy concern score (r?=?0.584, p<0.05) and the personal distress score (r?=?0.538, p<0.05) but not significantly associated with other empathy subscales. No significant correlation was found between ACC GABA and empathy subscores. Conclusion: Left AI GABA was positively correlated with the emotional aspects of empathy. These preliminary findings call into question whether AI GABA alterations might predict empathy dysfunction in major psychiatric disorders such as autism and schizophrenia, which have been described as deficits in emotional empathic abilities. PMID:25419976

Dong, Fang; Chen, Luguang; Zheng, Li; Guo, Xiuyan; Li, Jianqi

2014-01-01

193

Velocity Correlations in Foam Simulation

NASA Astrophysics Data System (ADS)

We use a simple bubble model of foams proposed by Durian (D.J. Durian, Phys. Rev. Lett. 75), 4780 (1995); Phys. Rev. E 55 1739 (1997) to study velocity correlations in a two-dimensional foam under steady-state shear flow. We study spatial correlations of the deviation of the velocity from the average flow. We find that the correlation function is strongly anisotropic, with different correlation lengths in the shear and shear gradient directions. We measure the correlation function as a function of strain rate, and find increasing spatial correlations as the strain rate decreases.

Ono, Ian; Tewari, Shubha; Liu, Andrea

1998-03-01

194

2005 Pearson Education South Asia Pte Ltd Applied Fluid Mechanics

Education South Asia Pte Ltd Applied Fluid Mechanics 17.Drag and Lift 18.Fans, Blowers, Compressors. Â· State the affinity laws for centrifugal pumps as they relate to the relationships among speed, impeller pressure of the fluid in relation to the NPSH. Â· Compute the NPSH available for a given suction line design

Leu, Tzong-Shyng "Jeremy"

195

HelenPearson A study highlighting statistical gaffes in

cloned a human somatic cell, creating an embryo that they used to establish a stem-cell line thera- peutic human embryonic cloning research," readsthestatementtheyissued. The questions, postedCyranoski,Tokyo Bioethicists are pushing for an investigation into the cloning work of a South Korean research team

GarcÃa-Berthou, Emili

196

THOMAS W. PEARSON University of WisconsinStout

director of Sol de Vida, a small NGO that promotes sustainable development in rural Guanacaste, a province transgenic seeds to neoliberal economic reforms, suggesting that pri- vate capital had infiltrated the inner

Wu, Mingshen

197

HelenPearson,NewYork Africa should pursue agricultural research

and animals; com- bining cereals and roots; irrigated systems; and tree crops. They urge African nations- dationswillbetranslatedintoactionandwho is going to cough up the cash. "That," says YvetteStevens,aUNadviserondevelopment in

Cai, Long

198

2005 Pearson Education South Asia Pte Ltd Applied Fluid Mechanics

Viscosity Grades 7. ISO Viscosity Grades 8. Hydraulic Fluids for Fluid Power Systems 2. Viscosity of Fluids proportional to the velocity gradient can be stated mathematically as where the constant of proportionality Ã?

Leu, Tzong-Shyng "Jeremy"

199

2005 Pearson Education South Asia Pte Ltd Applied Fluid Mechanics

Asia Pte Ltd Chapter Objectives Â· Use Newton's second law of motion, F = ma, to develop the force of a body is changed, a force is required to accomplish the change. Â· Newton's second law of motion is often is caused to undergo the acceleration, and a different form of Newton's equation is desirable. Â· Because

Leu, Tzong-Shyng "Jeremy"

200

James Pearson Duffy Department of Art and Art History

and Merchandising; and Studio Art. GTAs are awarded for one academic year, beginning with the Fall semester. Those and Merchandising; or Studio Art Please indicate below the area(s) in which you feel qualified for assisting

Berdichevsky, Victor

201

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 ...

202

2005 Pearson Education South Asia Pte Ltd Applied Fluid Mechanics

is not circular. Â· An example is the shell-and-tube heat exchanger shown in Fig. 9.1, in which, for example, hot profile for laminar and turbulent flow in circular pipes, tubes, or hose. Â· Describe the laminar boundary and turbulent flow. Â· The velocity at the pipe wall is zero. Â· The local velocity increases rapidly over a short

Leu, Tzong-Shyng "Jeremy"

203

Globalintime solutions for the isothermal MatovichPearson equations #

@math.univÂtoulouse.fr Andro Mikeliâ??c # Universitâ??e de Lyon, Lyon, FÂ69003, FRANCE ; Universitâ??e Lyon 1, Institut Camille Cedex, FRANCE EÂmail: Andro.Mikelic@univÂlyon1.fr June 3, 2010 Abstract In this paper we study

Recanati, Catherine

204

PREFACE: Correlated Electrons (Japan)

NASA Astrophysics Data System (ADS)

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.

Miyake, Kazumasa

2007-03-01

205

Correlation Between Dental Arch Width and Sagittal Dento-Skeletal Morphology in Untreated Adults

Objective: Dental arch form is one of the most important characteristics of dentition. However, this dimension usually receives less attention in diagnosis or treatment planning and orthodontic patients are traditionally classified with regard to their sagittal characteristics. The objectives of this study were to investigate if a relationship exists between the dental arch width (transverse dimension) and sagittal skeletal and dental parameters in orthodontic patients. Materials and Methods: Dental casts and lateral cephalograms of 108 consecutive untreated Iranian patients (47 males and 61 females) between 16 and 31 years of age were evaluated. Arch width (AW) parameters including upper and lower inter-molar width (UIMW and LIMW) and upper and lower inter-canine width (UICW and LICW) were measured by a digital caliper. Sagittal parameters included SNA and SNB angle and Wits’ appraisal obtained from lateral cephalograms in addition to upper and lower arch length (UAL and LAL) obtained from dental casts. The correlation between the aforementioned parameters was evaluated applying Pearson correlation coefficients. Molar and canine relationship according to Angle’s classification was also recorded and the means of all parameters were compared between three occlusal relationship classes and two gender groups by means of two-way ANOVA. Results: According to statistical analysis a significant positive correlation between sagittal parameters and arch width measures exists between SNA and UICW and between LICW and LAL. Upper and lower ICW were significantly correlated, the relationship between upper and lower IMW and between UAL and LAL were significant. Among sagittal measures, both UAL and LAL were correlated with the ANB angle. The means of arch width parameters in three occlusal classes were not significantly different. Conclusion: The only significant correlation between arch width and sagittal parameters existed between UICW and SNA angle and between LICW and LAL. No significant difference of the arch width parameter was observed between the three occlusal classes. PMID:24910663

Shahroudi, Atefe Saffar; Etezadi, Tahura

2013-01-01

206

Trust has been variously defined by behavioral scientists and not very thoroughly investigated. In this study trust was defined as an expectancy held by an individual that the behavior of another person or a group would be altruistic and personally beneficial. An attempt was made, using this conceptual definition, to identify some personality and behavioral correlates of trust. Seven interpersonal relations groups with approximately 10 male and female undergraduates per group were studied with use of the Janis and Field self-esteem inventory, Schutz's FIRO-B scale, and the Rotter internal-external scale. It was discovered that a trusted person is one who is highly influential, has an internal locus of control, a low need to control others, high self-esteem, and is open to being influenced by others. PMID:650598

Frost, T; Stimpson, D V; Maughan, M R

1978-05-01

207

NSDL National Science Digital Library

Research has shown that marital status and employment are correlates of desistance. That is, adolescents involved with crime were more likely to discontinue offending in adulthood if they were married and had a good job. Most of what criminologists know about the process of desistance from crime is based on a sample of adult males in the 1950's. There is no question that life in America has changed drastically in the past fifty years. Given the importance of examining historical change inherent in the life course perspective, it is important to determine how changes in the social structure over time impact individuals. Therefore, the goals of this data analysis exercise are to examine changes in marriage and employment over the last fifty years. The purposes are to identify the changes that have taken place, and to hypothesize how these changes may affect the process of desistance from crime today.

Ford, Jason

2009-08-17

208

NASA Astrophysics Data System (ADS)

We describe the software development effort for the first-light correlator of the Combined Array for Research in Millimeter-wave Astronomy (CARMA{http://www.mmarray.org/}), the merger of the Owens Valley Radio Observatory (OVRO{http://www.ovro.caltech.edu/}) and Berkeley-Illinois-Maryland Association (BIMA{http://bima.astro.umd.edu/}) millimeter arrays that is expected to reach first-light in 2005. The digital hardware relies on programmable logic devices (FPGAs), signal processors (DSPs), and Linux-based host computers acting in concert to produce baseline visibility data. We summarize the hardware configuration, the distribution of computational tasks among components, and the tools and techniques used to program these devices.

Rauch, K. P.; Hobbs, R.; Hawkins, D. W.

2005-12-01

209

Magnitude correlations in global seismicity

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.

Sarlis, N. V. [Solid State Section and Solid Earth Physics Institute, Physics Department, University of Athens, Panepistimiopolis, Zografos GR-157 84, Athens (Greece)

2011-08-15

210

Validation of Sensor Alert Correlators

The authors describe the first experimental validation of correlation systems with the goal of assessing the overall progress in the field. Their experiment set out to measure the collective ability of correlators to recognize cyber attacks and designate their targets.

Joshua W. Haines; Dorene Kewley Ryder; Laura Tinnel; Stephen Taylor

2003-01-01

211

NASA Astrophysics Data System (ADS)

Large "hierarchical" datasets, that is a dataset that consists of identifiable subsamples of a population, offer the possibility to calculate a statistic per subsample. Together they form a sample distribution of that statistic. This distribution may be compared to some null hypothesis distribution and tested for deviations. To determine whether two variables are related, some type of correlation statistic usually is calculated. If the assumption for a normal distribution is not true necessarily the nonparametric Spearman rank correlation coefficient is better suited to estimate the existence of a relation than the Pearson product-moment correlation coefficient. The Spearman rank correlation coefficient thus has more general applicability at the cost of only a marginal loss in efficiency in the situation of normality. The dBase program SPEARMEN calculates Spearman rank correlation coefficients for all the subsamples of a "hierarchical" dataset and tests the sample distribution of this statistic against the null hypothesis Ho: rs = 0 by using the Kolmogorov-Smirnov one sample test. This approach has the advantage that it is sensitive to deviations for the entire range of observations and not only at critical tail-end values. For subsample sizes under 14 the theoretical null hypothesis permutation distribution is used, whereas above this value the distribution is approximated by a Student- t distribution. The program uns under dBaseIII +, dBaseIV, Foxbase +, and Clipper and can be used for virtually unlimited datasets.

Frapporti, G.; Linnartz, L. A. M.; Vriend, S. P.

212

On turbulence-correlation analysis based on correlation reflectometry

NASA Astrophysics Data System (ADS)

Drift wave micro-turbulence is the main source of anomalous transport in a tokamak. Correlation reflectometry is a powerful diagnostic tool which provides information on plasma turbulence and subsequently on underlying instability. In this paper, theoretical expressions for the analysis of radial correlation reflectometry (RCR) data are derived. Integral kernels, which convert the correlation function of two microwave reflectometry signals into a correlation function of plasma turbulence and inverse, are discussed. The analytical expression and the method of combining the RCR diagnostic and another local density fluctuation (e.g. Doppler enhanced scattering or heavy ion beam probe) is proposed. The correlation between reflectometry signals and those from other local fluctuation measurements is analysed. The long-range tail of the correlation decays much more gradually than the turbulence correlation, however, it decays faster than that of two microwave reflectometry signals. The way to calculate turbulence wave number spectrum for this case is also proposed.

Teplova (Kosolapova, N.; Itoh, K.; Itoh, S.-I.; Gusakov, E.; Heuraux, S.; Inagaki, S.; Sasaki, M.; Kobayashi, T.; Nagashima, Y.; Oldenbürger, S.; Fujisawa, A.

2013-04-01

213

the development of cognitive architectures based on the structure and function of the brain. The goals to structures in the brain. We demonstrate a working implementation of the framework, where we have developed level posit direct mappings to structures and processes of neural systems in the brain. The achievements

Lewis, Richard

214

Direct measure of quantum correlation

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.

Yu, Chang-shui [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Zhao, Haiqing [School of Science, Dalian Jiaotong University, Dalian 116028 (China)

2011-12-15

215

Background: Multiple population-based human studies have established a strong association between increasing levels of serum C-reactive protein, uric acid and subsequent development of hypertension. Objectives: We aimed to investigate the association between mental well-being with presence of hypertension, hyperuricemia and hs-CRP levels. ?? Patients and Methods: This was a cross sectional study of 801 individuals aged 35-85 years old in Broujerd, Iran, included by randomized cluster sampling. General Health Questionnaire (GHQ-12) for assessing mental health/distress level, MONICA standard questions for evaluating hypertension history, serum hs-CRP and Serum Uric Acid (SUA) were evaluated Data were analyzed by appropriate statistical test such as chi-square, T-test and correlation. Results: One hundred eighty five patients (23.1%) had high distress/minor psychiatric disorders. SUA had significant association with hypertension (r = 0.64, P = 0.034). No significant relation was observed between hs-CRP and hypertension. The correlation between GHQ and hs-CRP was not significant but a weak and negative correlation was found between GHQ and SUA SUA (P = 0.012, r = -0.089). Conclusions: The weak and strong correlation among these parameters indicate that mental wellbeing relays on physical wellness and interact with each other; therefore, controlling hypertension along with uric acid control may effect mental health of any kind of patients. PMID:25237581

Maleki, Ali; Samandari, Saeid; Almeida, Osvaldo; Jafarian Kerman, Scott Reza; Abdolvand, Mahdi; Aliyari, Farshid; Foroughi, Saeid

2014-01-01

216

Data consisting of preadmission criteria scores, annual and final cumulative grade point averages (GPAs), grades from individual professional courses, American Veterinary Medical Association Council on Education (AVMA-COE) Competency scores, annual class rank, and North American Veterinary Licensing Exam (NAVLE) scores were collected on all graduating DVM students at Kansas State University in 2009 and 2010. Associations among the collected data were compared by Pearson correlation. Pre-veterinary admissions criteria infrequently correlated with annual GPAs of Years 1-3, rarely correlated with the AVMA-COE Competencies, and never correlated with the annual GPA of Year 4. Low positive correlations occurred between the NAVLE and the Verbal Graduate Record Examination (GRE) (r=.214), Total GRE (r=.171), and the mean GPA of pre-professional science courses (SGPA) (r=.236). Annual GPAs strongly correlated with didactic course scores. Annual GPAs and final class rank strongly correlated (mean r=-.849), and both strongly correlated with the NAVLE score (NAVLE: GPAs mean r=.628, NAVLE: final class rank r=-.714). Annual GPAs at the end of Years 1-4 weakly correlated or did not correlate with the AVMA-COE Competencies. The AVMA-COE Competencies weakly correlated with scores earned in didactic courses of Years 1-3. AVMA-COE Competencies were internally consistent (mean r=.796) but only moderately correlated with performance on the NAVLE (mean r=.319). Low correlations between admissions criteria and outcomes indicate a need to reevaluate admission criteria as predictors of school success. If the NAVLE remains the primary discriminator for veterinary licensure (and the gateway to professional activity), then the AVMA-COE Competencies should be refined to better improve and reflect the NAVLE, or the NAVLE examination should change to reflect AVMA-COE Competencies. PMID:24152428

Roush, James K; Rush, Bonnie R; White, Brad J; Wilkerson, Melinda J

2014-01-01

217

ERIC Educational Resources Information Center

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…

Prevost, A. Toby; Mason, Dan; Griffin, Simon; Kinmonth, Ann-Louise; Sutton, Stephen; Spiegelhalter, David

2007-01-01

218

Background: Methods learnt by nursing and midwifery students’ 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 students’ 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: Students’ total mean score from the Communication Skills Scale was 165.27 ± 15.39 and for the Life Orientation Test was 18.51 ± 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.

Özdemir, Gülsün; Kaya, Hatice

2013-01-01

219

Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?

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.

Love, J. J.; Mursula, K.; Tsai, V. C.; Perkins, D. M.

2011-01-01

220

To evaluate the construct validity (convergent and divergent) of the Sivik Psycho Somaticism test (SPS) and test of Operationality (OPER), Pearson correlation coefficients between SPS scales and subscales, OPER and Minnesota Multiphasic Personality Inventory (MMPI) subscales Hypochondria (Hs), Depression (D), Hysteria (Hy) and Alexithymia (Al) were calculated. Eighty-eight healthy individuals and 285 psychosomatic patients completed the SPS and OPER tests and MMPI; Hs, D, Hy and Al. The results show that most of the SPS subscales and OPER are significantly correlated to several MMPI subscales in both a normal and a psychosomatic population. The results are in concordance with the theoretical hypotheses and confirm the validity of the SPS and OPER constructs. PMID:10485607

Sivik, T; Delimar, N; Schoenfeld, R

1999-01-01

221

NASA Astrophysics Data System (ADS)

Images of the geostationary Meteosat-9 SEVIRI instrument during the year 2012 are analyzed with respect to the representativeness of the observations of eight cloud observatories in Europe. Cloudy situations are selected to get a time series for every pixel in a 300 km × 300 km area centered around each ground station. Then the Pearson correlation coefficient of each time series to the one of the pixel nearest to the corresponding ground site is calculated. The area for which a station is representative is defined by the characteristic radius around each station for each SEVIRI channel, where the average correlation falls below 0.9. It is found that measurements in the visible and near infrared channels, which respond to cloud microphysics, are correlated in an area with a 1 to 4 km radius, while the thermal channels, that correspond to cloud top temperature, are correlated to a distance of about 20 km. The defined radius even increases for the water vapor and ozone channels. While all stations in Central Europe are quite alike, the correlations around the station in the mountains of southern Italy are much lower. Additionally correlations at different distances corresponding to the grid box sizes of forecast models were compared. The results show good comparability between regional forecast models (grid size ? 10 km) and ground-based measurements since the correlations in less than 10 km distance are in all cases higher than 0.8. For larger distances like they are typical for global models (grid size ? 20 km) the correlations decrease to 0.6, especially for shortwave measurements and corresponding cloud products. By comparing daily means, the characteristic radius of each station is increased to about 3 to 10 times the value of instantaneous measurements and also the comparability to models grows.

Slobodda, J.; Hünerbein, A.; Lindstrot, R.; Preusker, R.; Ebell, K.; Fischer, J.

2014-06-01

222

Discovering Organizational Correlations from Twitter

Organizational relationships are usually very complex in real life. It is difficult or impossible to directly measure such correlations among different organizations, because important information is usually not publicly available (e.g., the correlations of terrorist organizations). Nowadays, an increasing amount of organizational information can be posted online by individuals and spread instantly through Twitter. Such information can be crucial for detecting organizational correlations. In this paper, we study the problem of discovering correlations among organizations from Twitter. Mining organizational correlations is a very challenging task due to the following reasons: a) Data in Twitter occurs as large volumes of mixed information. The most relevant information about organizations is often buried. Thus, the organizational correlations can be scattered in multiple places, represented by different forms; b) Making use of information from Twitter collectively and judiciously is difficult because of the mu...

Zhang, Jingyuan; Kong, Xiangnan; Shuai, Hong-Han; Yu, Philip S

2014-01-01

223

Measuring and interpreting neuronal correlations

Mounting evidence suggests that understanding how the brain encodes information and performs computations will require studying correlations between neurons. The recent advent of recording techniques such as multielectrode arrays and two-photon imaging has made it easier to measure correlations, opening the door to detailed exploration of their properties and contributions to cortical processing. Studies to date, however, have reported discrepant findings, providing a confusing picture. Here, we briefly review these studies and conduct simulations to explore the influence of several experimental and physiological factors on correlation measurements. Differences in response strength, the time window over which spikes are counted, spike sorting conventions, and internal states can all dramatically affect measured correlations and systematically bias estimates. Given these complicating factors, we offer guidelines for interpreting correlation data and a discussion of how best to evaluate the impact of correlations on cortical processing. PMID:21709677

Cohen, Marlene R.; Kohn, Adam

2013-01-01

224

Aims: The purpose of this study was to compare microbial penetration method and electrochemical technique for evaluation of the apical seal. Materials and Methods: A total of 28 teeth were prepared using the step-back technique to ISO size 40 master apical files. The specimens were randomly divided into an experimental group, two positive and two negative controls. Root canals in the experimental and negative control group were filled with gutta-percha (GP) and sealer, using lateral condensation technique. In the positive control group, canals were filled with GP without any sealer. The external surface of each tooth was coated with two layers of the nail varnish, except for the access opening and the apical foramen. In the negative control group, the teeth were completely covered with nail varnish. The apical seal was recorded with two methods, each successively used on the same teeth: An electrochemical method and a bacterial penetration method. Statistical Analysis Used: The correlation of the electro chemical readings with the results obtained from bacterial micro leakage test was evaluated by Pearson's correlation coefficient. Results: Correlation coefficient of the measurements obtained from the two evaluation methods, was 0.23 (r = 0.23), so the correlation was not statistically significant (P = 0.275). Conclusions: This study shows that several studies by different methods are necessary before evaluation of the marginal leakage. PMID:24808699

Kazemipoor, Maryam; Modaresi, Jalil; Zandi, Hengameh; Vasee, Narges; Farzaneh, Vaziri

2014-01-01

225

Cholinesterase is one of many important enzymes needed for acetylcholine hydrolysis. This study aimed to evaluate the serum pseudo-cholinesterase (BuChE) level and its relation to biological parameters (hematological and biochemical parameters) and symptoms among occupational workers, gasoline station worker in Bangkok, Thailand. Our results revealed that the average BuChE level was in normal range, but it had strong relation to hemoglobin (Hb), hematocrit (Hct), blood urea nitrogen (BUN), creatinine (Cr) and serum glutamic pyruvic trans-aminase (SGPT) (Linear regression analysis, p < 0.05, p < 0.05, p < 0.01, p = 0.001 and p < 0.01 respectively). Although, BuChE was not related to white blood cell parameters, but it may exhibit the skin irritation (p = 0.058) of the workers as it showed significant correlation to conjunctivitis and nausea (Pearson's correlation, p < 0.01 and p < 0.05). In conclusion, this finding may explain that BuChE was significantly related to red blood cells (RBC), liver and kidney functions. PMID:24426243

Tunsaringkarn, Tanasorn; Zapuang, Kalaya; Rungsiyothin, Anusorn

2013-10-01

226

Arterial input function derived from pairwise correlations between PET-image voxels

A metabolite corrected arterial input function is a prerequisite for quantification of positron emission tomography (PET) data by compartmental analysis. This quantitative approach is also necessary for radioligands without suitable reference regions in brain. The measurement is laborious and requires cannulation of a peripheral artery, a procedure that can be associated with patient discomfort and potential adverse events. A non invasive procedure for obtaining the arterial input function is thus preferable. In this study, we present a novel method to obtain image-derived input functions (IDIFs). The method is based on calculation of the Pearson correlation coefficient between the time-activity curves of voxel pairs in the PET image to localize voxels displaying blood-like behavior. The method was evaluated using data obtained in human studies with the radioligands [11C]flumazenil and [11C]AZ10419369, and its performance was compared with three previously published methods. The distribution volumes (VT) obtained using IDIFs were compared with those obtained using traditional arterial measurements. Overall, the agreement in VT was good (?3% difference) for input functions obtained using the pairwise correlation approach. This approach performed similarly or even better than the other methods, and could be considered in applied clinical studies. Applications to other radioligands are needed for further verification. PMID:23571279

Schain, Martin; Benjaminsson, Simon; Varnas, Katarina; Forsberg, Anton; Halldin, Christer; Lansner, Anders; Farde, Lars; Varrone, Andrea

2013-01-01

227

The Interpretation of Correlation Data.

and offspring may be the case as a consequence of genetic variability. On the other hand, "modifiability" may be a factor determining the value of the correlation. Babcock and Clausen7 state that Pearl and Surface show a lack of correlation between mothers... of breeding must be adopted that will discount at their proper values the influences of modifiability and genetic variability attending segregation. Hayes and Garbers discuss the early work in correlation of plant characters and yield, particularly...

Conner, A. B. (Arthur Benjamin)

1923-01-01

228

Real-time optical correlation.

A real-time coherent optical correlator is described that uses the Itek PROM as a recyclable filter recording medium. Operation of a joint transform correlator is compared to a conventional Vander Lugt system. Experimental results are shown for the joint transform system, including demonstrations of the effects of target alignment and scale and the correlation of random bit rasters for signal processing applications. PMID:20155072

Nisenson, P; Sprague, R A

1975-11-01

229

Quantum metrology in correlated environments

NASA Astrophysics Data System (ADS)

We analytically obtain the precision bounds of frequency measurements in correlated Markovian and non-Markovian environments using a variational approach. The metrological equivalence of product states and maximally entangled states persisting in maximally correlated Markovian and non-Markovian environments is verified using a standard Ramsey spectroscopy setup. Furthermore, we find that optimal measurements can be used to achieve a much higher resolution than standard Ramsey spectroscopy in correlated environments.

Xie, Dong; Wang, An Min

2014-06-01

230

Correlated Knowledge Gradients: Example alternatives

Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0;Correlated Knowledge Gradients: Example -4 -2 0 2 4 alternatives value 0 10 20 30 -10 -8 -6 -4 -2 0 num measurements log(KGfactor) 0 10 20 30 0 0.5 1 1.5 2 num measurements opportunitycost #12;Correlated Knowledge

Keinan, Alon

231

Photon correlations in multimode waveguides

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.

Poem, Eilon; Silberberg, Yaron [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel)

2011-10-15

232

Producing and Detecting Correlated atoms

We discuss experiments to produce and detect atom correlations in a degenerate or nearly degenerate gas of neutral atoms. First we treat the atomic analog of the celebrated Hanbury Brown Twiss experiment, in which atom correlations result simply from interference effects without any atom interactions.We have performed this experiment for both bosons and fermions. Next we show how atom interactions produce correlated atoms using the atomic analog of spontaneous four-wavemixing. Finally, we briefly mention experiments on a one dimensional gas on an atom chip in which correlation effects due to both interference and interactions have been observed.

Christoph I. Westbrook; Martijn Schellekens; Aurélien Perrin; Valentina Krachmalnicoff; Jose Carlos Viana Gomes; Jean-Baptiste Trebbia; Jérôme Estève; Hong Chang; Isabelle Bouchoule; Denis Boiron; Alain Aspect; Tom Jeltes; John McNamara; Wim Hogervorst; Wim Vassen

2006-09-04

233

EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems

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.

Filip Ronning; Cristian Batista

2011-01-01

234

Optical Correlator Performs Novelty Filtering

NASA Technical Reports Server (NTRS)

Experimental real-time optical correlator performs correlation and novelty filtering in photorefractive crystal. Crystal oriented enabling cross-polarization diffraction: together with polarizing beam splitter, increases signal-to-noise ratio. Laser and optical components expand, collimate, and divide laser beam.

Liu, Duncan Tsuen-Hsi; Chao, Tien-Hsin; Cheng, Li-Jen

1994-01-01

235

Correlation femtoscopy of small systems

NASA Astrophysics Data System (ADS)

The basic principles of the correlation femtoscopy, including its correspondence to the Hanbury Brown and Twiss intensity interferometry, are reexamined. The main subject of the paper is an analysis of the correlation femtoscopy when the source size is as small as the order of the uncertainty limit. It is about 1 fm for the current high energy experiments. Then the standard femtoscopy model of random sources is inapplicable. The uncertainty principle leads to the partial indistinguishability and coherence of closely located emitters that affect the observed femtoscopy scales. In thermal systems the role of corresponding coherent length is taken by the thermal de Broglie wavelength that also defines the size of a single emitter. The formalism of partially coherent phases in the amplitudes of closely located individual emitters is used for the quantitative analysis. The general approach is illustrated analytically for the case of the Gaussian approximation for emitting sources. A reduction of the interferometry radii and a suppression of the Bose-Einstein correlation functions for small sources due to the uncertainty principle are found. There is a positive correlation between the source size and the intercept of the correlation function. The peculiarities of the nonfemtoscopic correlations caused by minijets and fluctuations of the initial states of the systems formed in pp and e+e- collisions are also analyzed. The factorization property for the contributions of femtoscopic and nonfemtoscopic correlations into complete correlation function is observed in numerical calculations in a wide range of the model parameters.

Sinyukov, Yu. M.; Shapoval, V. M.

2013-05-01

236

Correlation Weights in Multiple Regression

ERIC Educational Resources Information Center

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…

Waller, Niels G.; Jones, Jeff A.

2010-01-01

237

Improved correlations for retrograde gases

. This correlation is as accurate as previous correlations, and in addition, to the composition, it includes the trends for molecular weight of heptanes plus fraction (A4WC7+), specific gravity of heptanes plus fraction (SGC7+), gas produced (GP) and fraction...

Crogh, Arne

2012-06-07

238

Influence in Canonical Correlation Analysis.

ERIC Educational Resources Information Center

The perturbation theory of the generalized eigenproblem is used to derive influence functions of each squared canonical correlation coefficient and the corresponding canonical vector pair. Three sample versions of these functions are described, and some properties are noted. Two obvious applications, multiple correlation and correspondence…

Romanazzi, Mario

1992-01-01

239

Personality Correlates of Polydrug Abuse.

ERIC Educational Resources Information Center

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…

Kilpatrick, Dean G.; And Others

240

Image Recognition Using Generalized Correlation.

National Technical Information Service (NTIS)

This paper investigates the use of generalized cross-correlation in pattern matching when the objects may be of one or two dimensions. Generalized correlation can be used to determine the amount of dilatation and rotation between a given template and an o...

L. E. McDonald

1977-01-01

241

Regularized Generalized Canonical Correlation Analysis

ERIC Educational Resources Information Center

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…

Tenenhaus, Arthur; Tenenhaus, Michel

2011-01-01

242

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

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, Silvère M

2012-06-01

243

Objective While probable causative agents have been identified (e.g., refluxate components, tobacco smoke), the definitive mechanism for inflammation-related laryngeal mucosal damage remains elusive. Multichannel intraluminal impedance combined with pH monitoring (MII/pH) has emerged as a sensitive tool for diagnosis and characterization of gastroesophageal reflux disease (GERD) with laryngopharyngeal manifestations. To determine the relationship between laryngeal signs and MII/pH, we examined correlations between Reflux Finding Score (RFS) ratings of videostroboscopic laryngeal examinations and findings from MII/pH. Study Design Correlational study. Methods Healthy, untreated volunteers (n =142) underwent reflux diagnosis using data acquired from MII/pH testing. Eight trained clinicians performed RFS ratings of corresponding laryngeal examinations. Averaged RFS ratings were compared to MII/pH data using Pearson correlation coefficients. The relationship between RFS and MII/pH findings and demographic/clinical information (age, sex, smoking status, reflux) was assessed using general linear modeling. Rater reliability was evaluated. Results Posterior commissure hypertrophy was negatively correlated with minutes of nonacid refluxate (R=-0.21, p=0.0115). General linear modeling revealed that 28-40% of the variance in ratings of ventricular obliteration, erythema/hyperemia, vocal fold edema, diffuse laryngeal edema, posterior commissure hypertrophy, and granulation/granuloma could be explained by main and interaction effects of age, sex, smoking status, and reflux. Intra- and inter-rater reliability for RFS were poor-fair. Conclusion These results support the theory that the RFS is not specific for reflux in healthy, untreated volunteers, suggesting there may be alternate explanations for inflammatory clinical signs commonly ascribed to reflux in this population. PMID:24782404

Jette, Marie E.; Gaumnitz, Eric A.; Birchall, Martin A.; Welham, Nathan V.; Thibeault, Susan L.

2014-01-01

244

Different Luminosity Correlation of GRBs

NASA Astrophysics Data System (ADS)

We report our recent understanding about a tight correlation between relative spectral lag and luminosity (or redshift) for ?-ray bursts. The latest investigations indicate that the empirical correlations got from BATSE bursts also exist for Swift/BAT ones. The special luminosity-lag correlation is much similar to that of the luminosity with pulse number proposed by Schaefer (2003), but largely different from most of others ever discovered. Note that our newly built luminosity-lag correlation predicts that luminosity should evolve with cosmological redshift as L p ? (1 + z)2.4±0.7 that is excellently confirmed by Salvaterra et al. (2012) and Geng & Huang (2013). In addition, it is also surprisingly found that the luminosity-lag correlation can account for both long and short Swift/BAT bursts, which might be an evidence of the same radiation mechanism for diverse burst groups.

Zhang, Z. B.; Liu, H. C.; Jiang, L. Y.; Chen, D. Y.

2014-11-01

245

Characterization of spatiotemporally complex gait patterns using cross-correlation signatures.

We hypothesize that spatiotemporal joint coupling patterns during gait are closely associated with musculoskeletal injury mechanics. Previous studies examining joint coupling, have primarily focused on coupling between single pairs of neighboring body segments or joints; thus falling short of characterizing the full spatiotemporal complexity across the entire gait apparatus. This study proposes the reliance on properties of the temporal cross-correlation of distinct joint variables as a means to characterize and detect differences in multiple segmental coupling pairs and to quantify how these couplings change between different gait conditions or test groups. In particular, for each subject, a characteristic diagram array is obtained whose entries include the maximum values of the cross-correlation between all pairs of joint variables as well as the associated phase shifts at which these maxima are recorded. Paired t-tests are then used to highlight significant differences in the corresponding entries between two gait conditions. In the present study, this technique was applied to angular displacement and velocity histories across 12 lower extremity joint variables, for healthy subjects with and without a brace on the right knee. As expected, the statistical analysis indicated that the temporal cross-correlations associated with the right knee-angle variables differed the most between the two gait conditions. In addition, significant differences (p<0.01) were found in the coupling between other pairs of joint variables, establishing a characteristic spatiotemporal signature for the changes from normative gait that result from reduced mobility at the knee. PMID:22390962

Park, Kiwon; Dankowicz, Harry; Hsiao-Wecksler, Elizabeth T

2012-05-01

246

Correlation of neurocognitive function and brain parenchyma volumes in children surviving cancer

NASA Astrophysics Data System (ADS)

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.

Reddick, Wilburn E.; White, Holly A.; Glass, John O.; Mulhern, Raymond K.

2002-04-01

247

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

248

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

Serefoglu, Ege Can; Karacay, Safak; Ozdemir, Ahmet Tunc; Kalkan, Mehmet; Yencilek, Faruk

2014-01-01

249

Correlation between Correlations Process and Time in Quantum Networks

We study a special inhomogeneous quantum network consisting of a ring of M pseudospins (here M = 4) sequentially coupled to one and the same central spin under the influence of given pulse sequences (quantum gate operations). This architecture could be visualized as a quantum Turing machine with a cyclic ``tape''. Rather than input-output-relations we investigate the resulting process, i.e. the correlation between one- and two-point expectation values (``correlations'') over various time-steps. The resulting spatio-temporal pattern exhibits many non-classical features including Zeno-effects, violation of temporal Bell-inequalities, and quantum parallelism. Due to the strange web of correlations being built-up, specific measurement outcomes for the tape may refer to one or several preparation histories of the head. Specific families of correlation functions are more stable with respect to dissipation than the total wavefunction.

Mahler, G; Kim, Ilki

1998-01-01

250

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.

Mirrione,M.M.; Mirrione, M.M.; Schulz, D.; Dewey, S.L.; Henn, F.A.

2009-12-06

251

Determining $?$ from cluster correlation function

It is shown how data on the cluster correlation function can be used in order to reconstruct the density of the pregalactic density field on the cluster mass scale. The method is applied to the data on the cluster correlation amplitude -- richness dependence. The spectrum of the recovered density field has the same shape as the density field derived from data on the galaxy correlation function which is measured as function of linear scales. Matching the two amplitudes relates the mass to the comoving scale it contains and thereby leads to a direct determination of $\\Omega$. The resultant density parameter turns out to be $\\Omega$=0.25.

A. Kashlinsky

1998-06-17

252

Pion correlations in Nuclear Matter

The saturation properties of the nuclear matter taking pion correlations into account is studied. We construct a Bogoliubov transformations for the pion pair operators and calculate the energy associated with the pion pairs. The pion dispersion relation is investigated. We next study the correlation energy due to one pion exchange in nuclear matter and neutron matter at random phase approximation using the generator coordinate method. The techniques of the charged pion correlations are discussed in the neutron matter calculations. We observe that there is no sign of the pion condensation in this model.

P. K. Panda; S. Sarangi; J. da Providência

2009-10-17

253

Correlation methods in cutting arcs

NASA Astrophysics Data System (ADS)

The present work applies similarity theory to the plasma emanating from transferred arc, gas-vortex stabilized plasma cutting torches, to analyze the existing correlation between the arc temperature and the physical parameters of such torches. It has been found that the enthalpy number significantly influence the temperature of the electric arc. The obtained correlation shows an average deviation of 3 % from the temperature data points. Such correlation can be used, for instance, to predict changes in the peak value of the arc temperature at the nozzle exit of a geometrically similar cutting torch due to changes in its operation parameters.

Prevosto, L.; Kelly, H.

2011-05-01

254

Quantum walks of correlated particles

Quantum walks of correlated particles offer the possibility to study large-scale quantum interference, simulate biological, chemical and physical systems, and a route to universal quantum computation. Here we demonstrate quantum walks of two identical photons in an array of 21 continuously evanescently-coupled waveguides in a SiOxNy chip. We observe quantum correlations, violating a classical limit by 76 standard deviations, and find that they depend critically on the input state of the quantum walk. These results open the way to a powerful approach to quantum walks using correlated particles to encode information in an exponentially larger state space.

Alberto Peruzzo; Mirko Lobino; Jonathan C. F. Matthews; Nobuyuki Matsuda; Alberto Politi; Konstantinos Poulios; Xiao-Qi Zhou; Yoav Lahini; Nur Ismail; Kerstin Wörhoff; Yaron Bromberg; Yaron Silberberg; Mark G. Thompson; Jeremy L. O'Brien

2010-06-24

255

Pseudopotentials for correlated electron systems

A scheme is developed for creating pseudopotentials for use in correlated-electron calculations. Pseudopotentials for the light elements H, Li, Be, B, C, N, O, and F, are reported, based on data from high-level quantum chemical calculations. Results obtained with these correlated electron pseudopotentials (CEPPs) are compared with data for atomic energy levels and the dissociation energies, molecular geometries and zero-point vibrational energies of small molecules obtained from coupled cluster single double triple (CCSD(T)) calculations with large basis sets. The CEPPs give better results in correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.

Trail, J R

2013-01-01

256

Spinocerebellar ataxias – genotype-phenotype correlations in 104 Brazilian families

OBJECTIVE: Spinocerebellar ataxias are neurodegenerative disorders involving the cerebellum and its connections. There are more than 30 distinct subtypes, 16 of which are associated with an identified gene. The aim of the current study was to evaluate a large group of patients from 104 Brazilian families with spinocerebellar ataxias. METHODS: We studied 150 patients from 104 families with spinocerebellar ataxias who had received molecular genetic testing for spinocerebellar ataxia types 1, 2, 3, 6, 7, 8, 10, 12, 17, and dentatorubral-pallidoluysian atrophy. A statistical analysis of the results was performed using basic descriptive statistics and the correlation coefficient (r), Student's t-test, chi-square test, and Yates' correction. The statistical significance level was established for p-values <0.05. RESULTS: The results show that the most common subtype was spinocerebellar ataxia 3, which was followed by spinocerebellar ataxia 10. Moreover, the comparison between patients with spinocerebellar ataxia 3, spinocerebellar ataxia 10, and other types of spinocerebellar ataxia revealed distinct clinical features for each type. In patients with spinocerebellar ataxia 3, the phenotype was highly pleomorphic, although the most common signs of disease included cerebellar ataxia (CA), ophthalmoplegia, diplopia, eyelid retraction, facial fasciculation, pyramidal signs, and peripheral neuropathy. In patients with spinocerebellar ataxia 10, the phenotype was also rather distinct and consisted of pure cerebellar ataxia and abnormal saccadic eye movement as well as ocular dysmetria. Patients with spinocerebellar ataxias 2 and 7 presented highly suggestive features of cerebellar ataxia, including slow saccadic ocular movements and areflexia in spinocerebellar ataxia 2 and visual loss in spinocerebellar ataxia 7. CONCLUSIONS: Spinocerebellar ataxia 3 was the most common subtype examined, followed by spinocerebellar ataxia 10. Patients with spinocerebellar ataxia 2 and 7 demonstrated highly suggestive features, whereas the phenotype of spinocerebellar ataxia 3 patients was highly pleomorphic and spinocerebellar ataxia 10 patients exhibited pure cerebellar ataxia. Epilepsy was absent in all of the patients with spinocerebellar ataxia 10 in this series. PMID:22666787

Teive, Hélio A. G.; Munhoz, Renato P.; Arruda, Walter O.; Lopes-Cendes, Iscia; Raskin, Salmo; Werneck, Lineu C.; Ashizawa, Tetsuo

2012-01-01

257

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

Verma, KG; Verma, P; Bansal, N; Basavaraju, S; Sachdeva, SK; Khosa, R

2014-01-01

258

The long-term variation, nature and correlations of outdoor (222)Rn and (220)Rn progeny concentrations measured during the period 1994-2009 were investigated. The time series of data were obtained within the framework of the monitoring program performed by the Environmental Radioactivity Monitoring Station (ERMS) Bac?u, a component part of the National Environmental Radioactivity Survey Network (NERSN), coordinated by National Environmental Protection Agency (NEPA). The measuring method is based on the total beta measurements of atmospheric aerosol filters, using a low background total beta counter and ((90)Sr/Y) reference standard. Analysis of the time series of progeny concentrations in the low atmosphere makes evident different patterns of variation of these concentrations: diurnal, seasonal and annual. A possible relationship of progeny concentration increase with global warming is emphasized. In order to find the dominant frequency of the physical processes determining progeny concentration variability the power spectrum has been used. The deterministic nature of the time series of concentrations has been studied making use of the autocorrelation function and stationarity of the original data and of their phase randomized time series. Also, the correlations with meteorological parameters have been investigated using Pearson's correlation coefficient with corresponding level of significance. PMID:21531056

Cuculeanu, Vasile; Simion, Florin; Simion, Elena; Geicu, Anton

2011-07-01

259

Background The aim of this study was to investigate the relationship between serum uric acid and renal function, expressed as estimated glomerular filtration rate (eGFR), in patients with stable coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM) in China. Methods Serum levels of uric acid and creatinine were determined in 526 enrolled patients diagnosed with stable CAD and T2DM. To assess renal function, eGFR was calculated using a modified MDRD formula suitable for the Chinese population. Patients’ anthropometric measurements were collected using standardized protocols, and 6-month follow-up results were collected and analyzed. Pearson’s correlation coefficient r was calculated and multivariate analysis was performed to evaluate the relationship between uric acid and renal function. Patients with eGFR < 60 mL/min/1.73 m2 were classified as having reduced renal function or chronic kidney disease (CKD) in this study. Results Uric acid levels were negatively associated with eGFR (P = 0.002), especially in patients with CKD (eGFR < 60 mL/min/1.73 m2) (P < 0.001). In patients with reduced renal function, the risk in the highest quartile of uric acid levels was higher than in the lowest quartile (odds ratio 9.18, 95% confidence interval: 4.01 - 21.01, P < 0.001). These associations remained after multiple adjustments for potential confounders and were recapitulated after 6-month follow-up. Conclusions Serum uric acid level is negatively associated with renal function, as assessed by eGFR, and serves as an independent predictor for CKD in patients with stable CAD and T2DM.

Chen, Zhong; Ding, Zhen; Fu, Cong; Yu, Chaojun; Ma, Genshan

2014-01-01

260

Pooling and Correlated Neural Activity

Correlations between spike trains can strongly modulate neuronal activity and affect the ability of neurons to encode information. Neurons integrate inputs from thousands of afferents. Similarly, a number of experimental techniques are designed to record pooled cell activity. We review and generalize a number of previous results that show how correlations between cells in a population can be amplified and distorted in signals that reflect their collective activity. The structure of the underlying neuronal response can significantly impact correlations between such pooled signals. Therefore care needs to be taken when interpreting pooled recordings, or modeling networks of cells that receive inputs from large presynaptic populations. We also show that the frequently observed runaway synchrony in feedforward chains is primarily due to the pooling of correlated inputs. PMID:20485451

Rosenbaum, Robert J.; Trousdale, James; Josic, Kresimir

2009-01-01

261

Transverse correlations in multiphoton entanglement

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.

Wen Jianming; Rubin, Morton H.; Shih Yanhua [Physics Department, University of Maryland, Baltimore County, Baltimore, Maryland 21250 (United States)

2007-10-15

262

Acoustic Correlates of Information Structure.

This paper reports three studies aimed at addressing three questions about the acoustic correlates of information structure in English: (1) do speakers mark information structure prosodically, and, to the extent they do; ...

Breen, Mara

263

Objective: Recently, quality of life is a concern of health in psychiatry. Schizophrenia is a disorder that has the most regressive effects in societies’ and patients’ behavioural, occupational and psychiatric aspects. The main purpose of this study was to evaluate the quality of life and global function of schizophrenia patients. Methods: A hundred schizophrenia patients (with DSM-IV-TR) who had a history of at least 10 years from the beginning of the disorder were collected. Demographic characteristics, type of schizophrenia, living condition and the quality of life scale (QLS) including: interpersonal relationship, instrumental role, intra psychic foundations and common objects and activities, were gathered. Patients' general functions were evaluated with Global Assessment of Functioning (GAF). Statistical analysis was performed by SPSS statistical software using Fisher’s exact test, analysis of variance (ANOVA), Dunken and Pearson’s correlation test. Results: In this study 67% of patients were male and 51% were female. They were comprised of residual (55%), paranoid (11%) and undifferentiated (33%) schizophrenia. They lived in institute (67%) and with their families (28%). There was a moderate correlation between QLS and GAF (p<0.01, r=0.2). A significant association was found between married and single patients in instrumental role (F: 2.97), P<0.05) but there was not a significant association in other domains. Correlation were found between undifferentiated and paranoid patients in interpersonal relationship (F: 2.97), P<0.05). However there weren’t any correlation in intra psychic foundation and common objects and activities domains. Also there were significant associations in GAF (F: 3.98), P<0.05) between uneducated and educated participants. There was not an association between the Mean of five domains and genders. Conclusion: Schizophrenia patients' quality of life is low which shows the value and reliability of Global Assessment Functioning that is usually used for every psychiatrics’ patients for V axis clinical diagnosis and indicated the clinical value of this scale. For this reason rehabilitation, social skill training of patients and supportive therapy in family are important. PMID:24644456

Hosseini, Seyed-Hamzeh; Karkhaneh Yousefi, Mahtab

2011-01-01

264

Magnetic correlations and neutron scattering

An introduction is given to the methods and results of some recent researches into statistical thermodynamics bearing upon the correlation functions of magnetic moments in Heisenberg-coupled spin-only magnets, and their intimate connection with neutron-scattering theory and practice is brought out. The interrelationships between the correlation function, the relaxation function, the generalized susceptibility, the power spectrum of the fluctuations and the

W. Marshall; R. D. Lowde

1968-01-01

265

Method of Correlated Basis Functions

The method of correlated basis functions provides a means of systematically exploiting our intuitive understanding of real physical systems. Here we seek especially to develop a formalism for describing systems of strongly interacting fermions, for example, nuclei and liquid He3, using a complete set of correlated functions Psim=FPhim(Phim, F2Phim)12. F is taken as a product of two-body factors, i

John W. Clark; Paul Westhaus

1966-01-01

266

Retention capacity of correlated surfaces.

We extend the water retention model [C. L. Knecht et al., Phys. Rev. Lett. 108, 045703 (2012)] to correlated random surfaces. We find that the retention capacity of discrete random landscapes is strongly affected by spatial correlations among the heights. This phenomenon is related to the emergence of power-law scaling in the lake volume distribution. We also solve the uncorrelated case exactly for a small lattice and present bounds on the retention of uncorrelated landscapes. PMID:25019758

Schrenk, K J; Araújo, N A M; Ziff, R M; Herrmann, H J

2014-06-01

267

Retention capacity of correlated surfaces

We investigate the water retention model [C. L. Knecht \\emph{et al.}, Phys. Rev. Lett. {\\bf 108}, 045703 (2012)] on correlated and uncorrelated random surfaces. We find that the retention capacity of discrete random landscapes is strongly affected by spatial correlations among the heights. This phenomenon is related to the emergence of power-law scaling in the lake volume distribution. We also solve the uncorrelated case exactly for a small lattice.

Schrenk, K J; Ziff, R M; Herrmann, H J

2014-01-01

268

Generalized drift-flux correlation

A one-dimensional drift-flux model with five conservation equations is frequently employed in major computer codes, such as TRAC-PD2, and in simulator codes. In this method, the relative velocity between liquid and vapor phases, or slip ratio, is given by correlations, rather than by direct solution of the phasic momentum equations, as in the case of the two-fluid model used in TRAC-PF1. The correlations for churn-turbulent bubbly flow and slug flow regimes were given in terms of drift velocities by Zuber and Findlay. For the annular flow regime, the drift velocity correlations were developed by Ishii et al., using interphasic force balances. Another approach is to define the drift velocity so that flooding and liquid hold-up conditions are properly simulated, as reported here. The generalized correlation is used to reanalyze the MB-2 test data for two-phase flow in a large-diameter pipe. The results are applied to the generalized drift flux velocity, whose relationship to the other correlations is discussed. Finally, the generalized drift flux correlation is implemented in TRAC-PD2. Flow reversal from countercurrent to cocurrent flow is computed in small-diameter U-shaped tubes and is compared with the flooding curve.

Takeuchi, K.; Young, M.Y.; Hochreiter, L.E. (Westinghouse Electric Corp., Pittsburgh, PA (United States))

1991-01-01

269

Purpose: Ayurveda is one of the most ancient systems of medical health care. The basic principles, diagnosis of the diseases and their treatment are based on individual prakriti (constitutional type). Ayurveda further classifies the prakriti of an individual on the basis of a set of psychosomatic attributes of personality, depending on whether this individual belongs to Vata, Pitta, or Kapha prakriti, or any combination of them (Patwardhan et al., 2005). The appropriate prakriti assessment is done by several means including questionnaires (Rastogi, 2012; Shilpa and Venkatesha-Murthy, 2011). We aimed to obtain experimental evidence correlating Ayurveda based tridosha-prakriti with western constitutional psychology somatotypes (Rizzo-Sierra, 2011). Method: We employed our Tridosha-prakriti questionnaire (Ramakrishna and Nagendra, 2012), and compared its results with a set of body composition parameters: Height, body weight, body mass index (BMI), muscle mass, fat mass, and fat percentage in normal healthy volunteers (25 males and 25 females, mean age was 26 (± 4) and 25 (± 6) years respectively). Moreover, two-tailed Pearson's correlations were investigated to match the extreme prakriti types with the western constitutional psychology somatotypes, through the mentioned body composition measures. Result: Significant negative correlations were observed between the percentage of Vata attributes as per the questionnaire in the individuals and their BMI, body weight and fat mass respectively (p<0.05). Similarly, there was a significant positive correlation between the percentage of Pitta attributes with the height, body weight, and muscle mass respectively. Also, a significant positive correlation was observed between the percentage of Kapha attributes with fat mass and fat percentage, along with a negative correlation with height. Conclusion: We provide evidence-linking Ayurveda to modern constitutional psychology. In this way, a concept such as prakriti is suggested to lie behind the body mass composition of an individual, and deserves attention within the scientific community.

Metri, Kashinath G; Bhargav, Hemant; Ramarao, Nagendra Hongasandra; Rizzo-Sierra; Basavakatti, Ramakrishna R

2012-01-01

270

Serum Levels of Melatonin and Oxidative Stress Markers and Correlation between Them in Infertile Men

Introduction: Infertility is the problem of 15% of young couples in different societies. One of the factors that could affect fertility is oxidative stress. Therefore, the aim of the present study is to investigate the level of Melatonin, a free radical scavenger, and its correlation with oxidative biomarkers in infertile men. Methods: For this purpose, fertile and infertile men in 2 groups, 30 people in each group, were studied. The fertile men were selected from husbands of patients admitted to Alzahra obstetric and gynecology hospital, according to WHO standards. The infertile men were selected from patients referred to infertility ward. Blood sampling from the participants carried out at a specific time, sera collected and the levels of malondialdehyde, total antioxidant capacity and Melatonin were detected in the sera. The data were analyzed using t-test and Sperman's correlation method. Results: Melatonin level in the sera from fertile men were 522 (39.32) ng/L and in infertile men were 511.78 (34.6) ng/L. MDA level in fertile and infertile men were 2.26 (0.34) vs 2.99 (0.44) nmol/ml which was significantly different. The level of TAC in the sera from fertile men were significantly higher than in infertile men. The result obtained for correlation coefficient Spearman's test revealed a significant, strong and direct correlation between Melatonin and TAC and a significant and reverse correlation between melatonin and MDA. Conclusion: It is concluded that melatonin could be involved in infertility. In other word, melatonin treatment and antioxidant-rich nutrition could help fertility by combating oxidative stress.

Soleimani Rad, Sara; Abbasalizadeh, Shamsi; Ghorbani Haghjo, Amir; Sadagheyani, Mehzad; Montaseri, Azadeh; Soleimani Rad, Jafar

2013-01-01

271

Objective. There are no reports comparing the protocols provided by rigid marker set (RMS) and point cluster technique (PCT), which are similar in terms of estimating anatomical landmarks based on markers attached to a segment. The purpose of this study was to clarify the correlation of the two different protocols, which are protocols for knee motion in gait, and identify whether measurement errors arose at particular periods during the stance phase. Methods. The study subjects were 10 healthy adults. All estimated anatomical landmarks were which their positions, calculated by each protocol of the PCT and RMS, were compared using Pearson's product correlation coefficients. To examine the reliability of the angle changes of the knee joint measured by RMS and the PCT, the coefficient of multiple correlations (CMCs) was used. Results. Although the estimates of the anatomical landmarks showed high correlations of >0.90 (P < 0.01) for the Y- and Z-coordinates, the correlations were low for the X-coordinates at all anatomical landmarks. The CMC was 0.94 for flexion/extension, 0.74 for abduction/adduction, and 0.71 for external/internal rotation. Conclusion. Flexion/extension and abduction/adduction of the knee by two different protocols had comparatively little error and good reliability after 30% of the stance phase. PMID:23029618

Fukaya, Takashi; Mutsuzaki, Hirotaka; Ida, Hirofumi; Wadano, Yasuyoshi

2012-01-01

272

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

Nagle, Anna S.; Nageswaren, Ashok R.; Haridas, Balakrishna; Mast, T. D.

2014-01-01

273

OBJECTIVES. This study sought to evaluate obesity as a potential explanatory factor for the increased relative risk for cardiovascular disease in Black compared with White women. METHODS. Familial associations for obesity and cardiovascular disease risk factors were assessed in 720 White and 580 Black mother-daughter pairs from the National Heart, Lung, and Blood Institute's Growth and Health Study by using Pearson's chi square, Spearman's correlations, and partial correlations. RESULTS. Black girls and mothers were significantly heavier and had higher body mass indices than their White counterparts. In each racial group, significant, positive mother-daughter correlations existed for weight, body mass index, and triceps skinfolds, and for all cardiovascular disease risk factors. Obesity measures correlated positively with systolic blood pressure and triglycerides and inversely with high-density lipoprotein cholesterol in girls and mothers of both races. Correlations between mothers and daughters for exercise and ideal body shape were weak and did not explain obesity associations. CONCLUSIONS. Intrafamilial associations of obesity, cardiovascular disease risk factors, and the obesity-cardiovascular disease risk factor relationship support the position that increased cardiovascular disease morbidity and mortality rates in Black women may be linked to excess obesity in Black women compared with White ones. PMID:7977914

Morrison, J A; Payne, G; Barton, B A; Khoury, P R; Crawford, P

1994-01-01

274

This study aims to investigate a possible correlation between vertical misfits and the stresses transmitted to implants from one-piece casted frameworks fabricated with 3 different materials: commercially pure titanium, cobalt chromium alloy, and nickel chromium titanium alloy. Twelve frameworks simulating screw-retained prosthesis were fabricated from a master cast with 5 implants. Each framework was screwed (20 Ncm) over a metal cast and the vertical mesial and distal misfits were measured using an optical microscope. The stresses transmitted to the implants were measured in a third model by a quantitative photoelastic analysis. Stress and vertical misfit data were statistically analyzed by ANOVA and least significant difference tests and the correlation tests were performed using Pearson Correlation Test (? = 0.05). Mean and standard deviation values of vertical misfit and stress over implants are presented, respectively: commercially pure titanium (29.09 ± 13.24 ?m and 11.38 ± 9.23 kPa), cobalt chromium alloy (27.05 ± 10.30 ?m and 15.83 ± 9.30 kPa), nickel chromium titanium alloy (24.95 ± 11.14 ?m and 16.39 ± 9.51 kPa). There were no significant differences for vertical misfit (P = 0.285). Regarding the stress analysis, there were significant differences between commercially pure titanium, cobalt chromium alloy, and nickel chromium titanium alloy (P = 0.035), with the lowest values for the commercially pure titanium. It may be concluded that stress over implants was affected by different procedures and materials for framework production. PMID:25329843

Barbosa, Gustavo Augusto Seabra; Bernardes, Sérgio Rocha; de França, Danilo Gonzaga Bernardo; das Neves, Flávio Domingues; de Mattos, Maria da Glória Chiarello; Ribeiro, Ricardo Faria

2014-11-01

275

Jet correlations - opportunities and pitfalls

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 R_AA. 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 occuring in triggered hard correlation observables is given, followed by a study of current jet correlation phenomenology in the light of the preceding discussion.

Thorsten Renk

2014-04-03

276

$t$ Tests, $F$ Tests and Otsu's Methods for Image Thresholding

Otsu's binarization method is one of the most popular image- thresholding methods; Student's -test is one of the most widely-used sta- tistical tests to compare two groups. This paper aims to stress the equiv- alence between Otsu's binarization method and the search for an optimal threshold that provides the largest absolute Student's -statistic. It is then naturally demonstrated that the

Jing-Hao Xue; D. Michael Titterington

2011-01-01

277

My Child Doesn't Test Well. Carnegie Perspectives

ERIC Educational Resources Information Center

The writer examines a variety of reasons why test performance may not always be a valid measure of a person's competence or potential. Citing that a sizable percentage of students perform well in their schoolwork but poorly on standardized, multiple-choice tests, Bond defines and discusses four candidates as source factors for the phenomenon: (1)…

Bond, Lloyd

2007-01-01

278

Modified t Tests and Confidence Intervals for Asymmetrical Populations

This article considers a procedure that reduces the effect of population skewness on the distribution of the t variable so that tests about the mean can be more correctly computed. A modification of the t variable is obtained that is useful for distributions with skewness as severe as that of the exponential distribution. The procedure is generalized and applied to

Norman J. Johnson

1978-01-01

279

Successful applications of the gene ontology to the inference of functional relationships between gene products in recent years have raised the need for computational methods to automatically calculate semantic similarity between gene products based on semantic similarity of gene ontology terms. Nevertheless, existing methods, though having been widely used in a variety of applications, may significantly overestimate semantic similarity between genes that are actually not functionally related, thereby yielding misleading results in applications. To overcome this limitation, we propose to represent a gene product as a vector that is composed of information contents of gene ontology terms annotated for the gene product, and we suggest calculating similarity between two gene products as the relatedness of their corresponding vectors using three measures: Pearson's correlation coefficient, cosine similarity, and the Jaccard index. We focus on the biological process domain of the gene ontology and annotations of yeast proteins to study the effectiveness of the proposed measures. Results show that semantic similarity scores calculated using the proposed measures are more consistent with known biological knowledge than those derived using a list of existing methods, suggesting the effectiveness of our method in characterizing functional relationships between gene products. PMID:24963342

Gan, Mingxin

2014-01-01

280

Successful applications of the gene ontology to the inference of functional relationships between gene products in recent years have raised the need for computational methods to automatically calculate semantic similarity between gene products based on semantic similarity of gene ontology terms. Nevertheless, existing methods, though having been widely used in a variety of applications, may significantly overestimate semantic similarity between genes that are actually not functionally related, thereby yielding misleading results in applications. To overcome this limitation, we propose to represent a gene product as a vector that is composed of information contents of gene ontology terms annotated for the gene product, and we suggest calculating similarity between two gene products as the relatedness of their corresponding vectors using three measures: Pearson's correlation coefficient, cosine similarity, and the Jaccard index. We focus on the biological process domain of the gene ontology and annotations of yeast proteins to study the effectiveness of the proposed measures. Results show that semantic similarity scores calculated using the proposed measures are more consistent with known biological knowledge than those derived using a list of existing methods, suggesting the effectiveness of our method in characterizing functional relationships between gene products. PMID:24963342

2014-01-01

281

The aims of the current study were to examine the stationarities of surface electromyographic (EMG) signals obtained from eight bilateral back and hip muscles during a modified Biering-Sørensen test, and to investigate whether short-time Fourier (STFT) and continuous wavelet transforms (CWT) provided similar information with regard to EMG spectral parameters in the analysis of localized muscle fatigue. Twenty healthy subjects participated in the study after giving their informed consent. Reverse arrangement tests showed that 91.6% of the EMG signal epochs demonstrated no significant trends (all p>0.05), meaning 91.6% of the EMG signal epochs could be considered as stationary signals. Pearson correlation coefficients showed that STFT and CWT in general provide similar information with respect to the EMG spectral variables during isometric back extensions, and as a consequence STFT can still be used. PMID:18396411

Coorevits, Pascal; Danneels, Lieven; Cambier, Dirk; Ramon, Herman; Druyts, Hans; Stefan Karlsson, J; Moor, Georges De; Vanderstraeten, Guy

2008-08-01

282

Reveal quantum correlation in complementary bases

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

Wu, Shengjun; Ma, Zhihao; Chen, Zhihua; Yu, Sixia

2014-01-01

283

Quantum correlation via quantum coherence

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition--------quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes of quantum coherence. We propose a revised measure for total coherence and find that this measure can lead to a symmetric version of geometric quantum correlation which is analytic for two qubits. In particular, this measure can also arrive at a monogamy equality on the distribution of quantum coherence. Finally, we also quantify a remaining type of quantum coherence and find that for two qubits it is directly connected with quantum nonlocality.

Chang-shui Yu; Yang Zhang; Haiqing Zhao

2014-02-19

284

Storage capacity of correlated perceptrons

NASA Astrophysics Data System (ADS)

We consider an ensemble of K single-layer perceptrons exposed to random inputs and investigate the conditions under which the couplings of these perceptrons can be chosen such that prescribed correlations between the outputs occur. A general formalism is introduced using a multiperceptron cost function that allows one to determine the maximal number of random inputs as a function of the desired values of the correlations. Replica-symmetric results for K=2 and K=3 are compared with properties of two-layer networks of tree-structure and fixed Boolean function between hidden units and output. The results show which correlations in the hidden layer of multilayer neural networks are crucial for the value of the storage capacity.

Malzahn, D.; Engel, A.; Kanter, I.

1997-06-01

285

Spatiotemporal correlations of aftershock sequences

Aftershock sequences are of particular interest in seismic research since they may condition seismic activity in a given region over long time spans. While 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 model does not capture the spatiotemporal correlations leading to the observed structure of seismicity on small spatial scales.

Tiago P. Peixoto; Katharina Doblhoff-Dier; Jörn Davidsen

2010-04-12

286

Correlated optical and isotopic nanoscopy

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. PMID:24718107

Saka, Sinem K.; Vogts, Angela; Krohnert, Katharina; Hillion, Francois; Rizzoli, Silvio O; Wessels, Johannes T.

2014-01-01

287

Extremely correlated quantum liquids B. Sriram Shastry

strongly correlated electron systems. The latter deals with models such as the Hubbard model for transition; published 20 January 2010 Extreme correlations arise as the limit of strong correlations, when the local-J model, embodying such extreme correlations. We formulate the picture of an extremely correlated electron

California at Santa Cruz, University of

288

Background: Managing dental caries in young children is demanding due to the elusions present on the right diagnostic criteria for treatment. The present study evaluated the histological status of pulp tissues extracted from primary second molar with caries involvement. Histological findings are correlated with clinical and radiographic assessment. Materials and Methods: Simple experimental study was conducted on upper or lower second primary molars with occlusal (22 teeth) or proximal (22 teeth) dental caries. Selected children were below 6 years of age. Percentage of caries involvement, residual dentin thickness (RDT), radiographic assessment of interradicular and periapical areas, clinical caries depth and signs and symptoms are the parameters considered for comparing with the histological findings. The specimens were grouped based on the nature of the inflammatory process as acute or chronic. The data were analyzed by Student t-test to compare histological types of inflammation with clinical parameters. P value < 0.05 was considered as significant. Results: Four cases revealed severe acute inflammation in coronal and relatively mild acute inflammation in radicular pulp. In the rest of the specimen coronal and radicular pulp had similar acute or chronic inflammatory changes. Histological evidence of pulpitis correlated with dental caries depth of ?80%, RDT of ?1 mm, radiographic rarefactions in the interradicular regions and symptoms of pain. Conclusion: Primary second molars with more than two-third caries involvement with symptoms of pain histologically showed inflammation of both coronal and radicular pulp tissues in all cases. PMID:24932190

Gopinath, Vellore Kannan; Anwar, Khurshid

2014-01-01

289

Universal Fluctuations in Correlated Systems

NASA Astrophysics Data System (ADS)

The probability density function (PDF) of a global measure in a large class of highly correlated systems has been suggested to be of the same functional form. Here, we identify the analytical form of the PDF of one such measure, the order parameter in the low temperature phase of the 2D XY model. We demonstrate that this function describes the fluctuations of global quantities in other correlated equilibrium and nonequilibrium systems. These include a coupled rotor model, Ising and percolation models, models of forest fires, sandpiles, avalanches, and granular media in a self-organized critical state. We discuss the relationship with both Gaussian and extremal statistics.

Bramwell, S. T.; Christensen, K.; Fortin, J.-Y.; Holdsworth, P. C. W.; Jensen, H. J.; Lise, S.; López, J. M.; Nicodemi, M.; Pinton, J.-F.; Sellitto, M.

2000-04-01

290

Radiographic correlation in orthopedic pathology.

Radiographic correlation is an essential adjunct for the accurate diagnosis of orthopedic lesions, yet it is a skill neglected by pathologists. The purpose of this review is to demonstrate why performing this correlation is an essential part of the diagnostic process and not merely an interesting adjunct to the surgical pathology of orthopedic lesions. The relationships between x-rays and tissues are explored with an emphasis on bone and soft tissue composition and structure. In addition, the rudiments of complementary imaging studies and how to incorporate their data into diagnoses are examined. PMID:16096379

Klein, Michael J

2005-07-01

291

Pairing correlations and effective mass

We study the effect of effective mass on pairing correlations in the ground states of superfluid nuclei {sup 124}Sn and {sup 136}Sn. Various parameter sets of Skyrme interactions and relativistic Lagrangians are adopted to study pairing correlations across a wide range of effective mass. It is shown that surface-type pairing interaction gives an almost constant pairing gap as a function of the effective mass, while volume-type pairing interaction shows rather strong dependence of the pairing gap upon the effective mass. The local pair potentials of various effective interactions are also examined in relation to the effective mass.

Yoshida, Satoshi [Science Research Center, Hosei University, 2-17-1 Fujimi, Chiyoda, Tokyo 102-8160 (Japan); Sagawa, Hiroyuki [Center for Mathematical Sciences, University of Aizu Aizu-Wakamatsu, Fukushima 965-8580 (Japan)

2008-05-15

292

Petascale cross correlation in software

NASA Astrophysics Data System (ADS)

The exascale computational demands of back-end processing in the era of the SKA and HERA, headlined by the needs of cross-correlation, are likely to require solutions that differ significantly from traditional approaches on smaller arrays. The rapid growth of massively-parallel general-purpose computing hardware presents an alternative to ASIC- or FPGA-based designs and promises several advantages. In this talk we present strong scaling results for an FX correlator that runs entirely in software on GPU-based off-the-shelf HPC clusters.

Barsdell, Benjamin R.; Clark, M. A.; Greenhill, L. J.

2014-04-01

293

Top Quark Spin Correlations - Theory

The top quark decay width (G{sub F}m{sub t}{sup 3} {approx} 1 GeV) is much larger than the QCD hadronization scale ({Lambda}{sub QCD} {approx} 0.1 GeV) and much larger than the spin decorrelation scale ({Lambda}{sub QCD}{sup 2}/m{sub t} {approx} 0.1 MeV). Therefore, spin correlations in top quark pair production are reflected in angular correlations of the decay products, see [1] and [2].

Parke, Stephen J.; /Fermilab

2012-02-01

294

NASA Astrophysics Data System (ADS)

In an effort to infer compositional information about distant targets based on multispectral imaging data, we investigated methods of relating Mars Exploration Rover (MER) Pancam multispectral remote sensing observations to in situ alpha particle X-ray spectrometer (APXS)-derived elemental abundances and Mössbauer (MB)-derived abundances of Fe-bearing phases at the MER field sites in Gusev crater and Meridiani Planum. The majority of the partial correlation coefficients between these data sets were not statistically significant. Restricting the targets to those that were abraded by the rock abrasion tool (RAT) led to improved Pearson’s correlations, most notably between the red-blue ratio (673 nm/434 nm) and Fe3+-bearing phases, but partial correlations were not statistically significant. Partial Least Squares (PLS) calculations relating Pancam 11-color visible to near-IR (VNIR; ?400-1000 nm) “spectra” to APXS and Mössbauer element or mineral abundances showed generally poor performance, although the presence of compositional outliers led to improved PLS results for data from Meridiani. When the Meridiani PLS model for pyroxene was tested by predicting the pyroxene content of Gusev targets, the results were poor, indicating that the PLS models for Meridiani are not applicable to data from other sites. Soft Independent Modeling of Class Analogy (SIMCA) classification of Gusev crater data showed mixed results. Of the 24 Gusev test regions of interest (ROIs) with known classes, 11 had >30% of the pixels in the ROI classified correctly, while others were mis-classified or unclassified. k-Means clustering of APXS and Mössbauer data was used to assign Meridiani targets to compositional classes. The clustering-derived classes corresponded to meaningful geologic and/or color unit differences, and SIMCA classification using these classes was somewhat successful, with >30% of pixels correctly classified in 9 of the 11 ROIs with known classes. This work shows that the relationship between SWIR multispectral imaging data and APXS- and Mössbauer-derived composition/mineralogy is often weak, a perhaps not entirely unexpected result given the different surface sampling depths of SWIR imaging (uppermost few microns) vs. APXS (tens of ?m) and MB measurements (hundreds of ?m). Results from the upcoming Mars Science Laboratory (MSL) rover’s ChemCam Laser Induced Breakdown Spectroscopy (LIBS) instrument may show a closer relationship to Mastcam SWIR multispectral observations, however, because the initial laser shots onto a target will analyze only the upper few micrometers of the surface. The clustering and classification methods used in this study can be applied to any data set to formalize the definition of classes and identify targets that do not fit in previously defined classes.

Anderson, Ryan B.; Bell, James F.

2013-03-01

295

In an effort to infer compositional information about distant targets based on multispectral imaging data, we investigated methods of relating Mars Exploration Rover (MER) Pancam multispectral remote sensing observations to in situ alpha particle X-ray spectrometer (APXS)-derived elemental abundances and Mössbauer (MB)-derived abundances of Fe-bearing phases at the MER field sites in Gusev crater and Meridiani Planum. The majority of the partial correlation coefficients between these data sets were not statistically significant. Restricting the targets to those that were abraded by the rock abrasion tool (RAT) led to improved Pearson’s correlations, most notably between the red–blue ratio (673 nm/434 nm) and Fe3+-bearing phases, but partial correlations were not statistically significant. Partial Least Squares (PLS) calculations relating Pancam 11-color visible to near-IR (VNIR; ?400–1000 nm) “spectra” to APXS and Mössbauer element or mineral abundances showed generally poor performance, although the presence of compositional outliers led to improved PLS results for data from Meridiani. When the Meridiani PLS model for pyroxene was tested by predicting the pyroxene content of Gusev targets, the results were poor, indicating that the PLS models for Meridiani are not applicable to data from other sites. Soft Independent Modeling of Class Analogy (SIMCA) classification of Gusev crater data showed mixed results. Of the 24 Gusev test regions of interest (ROIs) with known classes, 11 had >30% of the pixels in the ROI classified correctly, while others were mis-classified or unclassified. k-Means clustering of APXS and Mössbauer data was used to assign Meridiani targets to compositional classes. The clustering-derived classes corresponded to meaningful geologic and/or color unit differences, and SIMCA classification using these classes was somewhat successful, with >30% of pixels correctly classified in 9 of the 11 ROIs with known classes. This work shows that the relationship between SWIR multispectral imaging data and APXS- and Mössbauer-derived composition/mineralogy is often weak, a perhaps not entirely unexpected result given the different surface sampling depths of SWIR imaging (uppermost few microns) vs. APXS (tens of ?m) and MB measurements (hundreds of ?m). Results from the upcoming Mars Science Laboratory (MSL) rover’s ChemCam Laser Induced Breakdown Spectroscopy (LIBS) instrument may show a closer relationship to Mastcam SWIR multispectral observations, however, because the initial laser shots onto a target will analyze only the upper few micrometers of the surface. The clustering and classification methods used in this study can be applied to any data set to formalize the definition of classes and identify targets that do not fit in previously defined classes.

Anderson, Ryan B.; Bell, James F., III

2013-01-01

296

PREFACE: Strongly correlated electron systems Strongly correlated electron systems

NASA Astrophysics Data System (ADS)

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 go—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

Saxena, Siddharth S.; Littlewood, P. B.

2012-07-01

297

Neural correlates of thought suppression

The present report used functional magnetic resonance imaging (fMRI) to examine the neural correlates of thought suppression. Subjects were imaged while alternately (i) attempting to suppress a particular thought, (ii) attempting to suppress all thoughts, or (iii) thinking freely about any thought. Suppression of a particular thought, when compared to the free-thought control condition, revealed greater activation in the anterior

Carrie L. Wyland; William M. Kelley; C. Neil Macrae; Heather L. Gordon; Todd F. Heatherton

2003-01-01

298

Sample Size and Correlational Inference

ERIC Educational Resources Information Center

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,…

Anderson, Richard B.; Doherty, Michael E.; Friedrich, Jeff C.

2008-01-01

299

The Physiological Correlates of Learning.

ERIC Educational Resources Information Center

The author reviews the literature and makes tentative conclusions concerning the physiological correlates of learning and memory. Particular attention is given to the issues of spinal cord learning, subcortical learning, cerebral cortex learning, localization of learning within the brain (specificity vs. non-specificity), and association areas…

Davis, Mary

300

Multibin long-range correlations

A new method to study the long-range correlations in multiparticle production is developped. It is proposed to study the joint factorial moments or cumulants of multiplicity distributions in several (more than two) bins. It is shown that this step dramatically increases the discriminative power of data.

A. Bialas; K. Zalewski

2011-01-10

301

Echoes in correlated neural systems

NASA Astrophysics Data System (ADS)

Correlations are employed in modern physics to explain microscopic and macroscopic phenomena, like the fractional quantum Hall effect and the Mott insulator state in high temperature superconductors and ultracold atoms. Simultaneously probed neurons in the intact brain reveal correlations between their activity, an important measure to study information processing in the brain that also influences the macroscopic signals of neural activity, like the electroencephalogram (EEG). Networks of spiking neurons differ from most physical systems: the interaction between elements is directed, time delayed, mediated by short pulses and each neuron receives events from thousands of neurons. Even the stationary state of the network cannot be described by equilibrium statistical mechanics. Here we develop a quantitative theory of pairwise correlations in finite-sized random networks of spiking neurons. We derive explicit analytic expressions for the population-averaged cross correlation functions. Our theory explains why the intuitive mean field description fails, how the echo of single action potentials causes an apparent lag of inhibition with respect to excitation and how the size of the network can be scaled while maintaining its dynamical state. Finally, we derive a new criterion for the emergence of collective oscillations from the spectrum of the time-evolution propagator.

Helias, M.; Tetzlaff, T.; Diesmann, M.

2013-02-01

302

Circumplex Models for Correlation Matrices.

ERIC Educational Resources Information Center

Structural models that yield circumplex inequality patterns are reviewed, focusing on a model developed by T. W. Anderson (1960). A modification is proposed to this model to allow for negative correlations. This model may be reparameterized as a factor analysis model with nonlinear constraints on the factor loadings. (SLD)

Browne, Michael W.

1992-01-01

303

FINCH: Fresnel Incoherent Correlation Hologram

6 FINCH: Fresnel Incoherent Correlation Hologram Joseph Rosen1, Barak Katz1 and Gary Brooker2 1Ben of view #12;Holography, Research and Technologies136 (Li et al., 2001; Sando et al., 2003; Shaked & Rosen holography (Poon & Korpel, 1979; Schilling et al., 1997; Poon, 2004; Rosen et al., 2006; Poon, 2007) in which

Rosen, Joseph

304

Object tracking through adaptive correlation

Current U.S. Air Force interests include a desire to track an object based on its shape once it has been designated as a target. This paper discusses the use of a correlation based system to track an object through a series of images based on templates derived from previous image frames. The ability to track is extended to sequences which

Dennis A. Montera; Steven K. Rogers; Dennis W. Ruck; Mark E. Oxley

1993-01-01

305

Multiparticle Bose-Einstein correlations

Multiparticle symmetrization effects are contributions to the spectra of Bose-symmetrized states which are not the product of pairwise correlations. Usually they are neglected in particle interferometric calculations which aim at determining the geometry of the boson emitting source from the measured momentum distributions. Based on a method introduced by Zajc and Pratt, we give a calculation of all multiparticle symmetrization

Urs Achim Wiedemann

1998-01-01

306

Multilevel Modeling with Correlated Effects

ERIC Educational Resources Information Center

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…

Kim, Jee-Seon; Frees, Edward W.

2007-01-01

307

The aim of this study was to test the hypotheses that epicardial adipose tissue (EAT) can be a marker of severe coronary artery disease in patients with acute myocardial infarction. Overall, 373 cases who underwent coronary angiography were classified into 2 groups by SYNTAX score: low-score and high-score group. EAT was measured by transthoracic echocardiography. Obtained data were compared using Pearson correlation analyses and univariate and multiple logistic regression analysis. The results showed that EAT in the high-score group was significantly greater than in the normal group (5.6 ± 1.1 vs. 4.1 ± 1.0 mm, P < 0.01). EAT had a positive correlation with SYNTAX score (r = 0.61, P < 0.01). Receiver operating characteristic (ROC) curve analyses showed that EAT could reliably discriminate patients with high SYNTAX score (?33) [AUC: 0.86, 95% confidence interval (CI): 0.822-0.898, P < 0.01]. Multivariate regression analyses showed that EAT was an independent predictor for major in-hospital events. These data showed an association between EAT and SYNTAX score. PMID:24645963

Wang, Tao; Liu, Qiang; Liu, Cuixia; Sun, Ling; Li, Daixu; Liu, Aihua; Jia, Ruyi

2014-11-01

308

Claudin 1 is one of the tight junction proteins, which are critical in the maintenance of epithelial integrity. Aberrant regulation of CLDN1 and its correlation with ?-catenin have been discovered in malignant tumors. The present study aimed to investigate the expression profile and clinical relevance of CLDN1 and ?-catenin. The protein levels of CLDN1 and ?-catenin were examined using immunohistochemical staining. The characteristics of expression profile and prognostic value were analyzed using Pearson's ?² test and Kaplan-Meier analysis, respectively. ?-catenin overexpression and knockdown were used to investigate its role in regulating CLDN1 expression. We showed that CLDN1 was overexpressed in intestinal-type, presence of lymph node metastasis, higher TNM stage in gastric cancer patients and correlated with decreased overall survival. The characteristics of CLDN1 expression were associated with that of ?-catenin. CLDN1 and ?-catenin showed similar prognostic value in intestinal-type gastric cancers. ?-catenin knockdown and overexpression in cell models revealed a positive relation between CLDN1 and ?-catenin. Our study demonstrated that CLDN1 is a biomarker for intestinal-type gastric cancer with shorter survival. The expression of CLDN1 was strongly associated with ?-catenin in gastric cancer patients and a gastric cancer cell model. PMID:24535143

Huang, Jie; Li, Jianfang; Qu, Ying; Zhang, Jianian; Zhang, Li; Chen, Xuehua; Liu, Bingya; Zhu, Zhenggang

2014-04-01

309

Classical and Quantum Correlated Percolation

NASA Astrophysics Data System (ADS)

Percolation is the study of connected structures in disordered networks. As edges are randomly and independently added to the network, clusters of neighboring edges grow in size until there ultimately exists a percolating cluster. The emergence of this percolating cluster exhibits properties of a continuous phase transition. The simplicity of uncorrelated percolation makes it the Ising model of connectivity-driven phase transitions. This thesis documents a quest to go beyond uncorrelated percolation and investigate transitions in correlated percolation models where there are constraints on the addition of edges (or vertices). Such constraints are inspired by glassy and jamming systems, for example. More specifically, we discuss several correlated percolation models, the

Cao, Liang

310

NASA Astrophysics Data System (ADS)

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.

Reddick, Wilburn E.; Glass, John O.; Shan, Zuyao Y.; Wu, Shengjie; Helton, Susan; Mulhern, Raymond K.

2005-04-01

311

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

Merolla, Giovanni; Campi, Fabrizio; Paladini, Paolo; Lollino, Nicola; Fauci, Francesco; Porcellini, Giuseppe

2009-04-01

312

A Correlation Study of Student Attitudes Toward Science in a Southern State High School

NASA Astrophysics Data System (ADS)

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.

Barco-Southall, Crystal

313

Background Epithelial ovarian cancer (EOC) is one of the most lethal gynecological cancers; the majority of EOC is the serous histotype and diagnosed at advanced stage. IL6 is the cytokine that has been found most frequently associated with carcinogenesis and progression of serous EOCs. IL6 is a growth-promoting and anti-apoptotic factor, and high plasma levels of IL6 in advanced stage EOCs correlate with poor prognosis. The objective of the present study was to identify IL6 co-regulated genes and gene network/s in EOCs. Results We applied bioinformatics tools on 7 publicly available data sets containing the gene expression profiles of 1262 EOC samples. By Pearson's correlation analysis we identified, in EOCs, an IL6-correlated gene signature containing 40 genes mainly associated with proliferation. 33 of 40 genes were also significantly correlated in low malignant potential (LMP) EOCs, while 7 genes, named C5AR1, FPR1, G0S2, IL8, KLF2, MMP19, and THBD were IL6-correlated only in advanced stage EOCs. Among the 40-gene signature EGFR ligand HBEGF, genes of the EGR family members and genes encoding for negative feedback regulators of growth factor signaling were included. The results obtained by Gene Set Enrichment and Ingenuity Pathway Analyses enabled the identification, respectively, of gene sets associated with ‘early growth factor response’ for the 40-gene signature, and a biological network related to ‘thrombosis and cardiovascular disease’ for the 7-gene signature. In agreement with these results, selected genes from the identified signatures were validated in vitro by real time RT-PCR in serous EOC cell lines upon stimulation with EGF. Conclusions Serous EOCs, independently of their aggressiveness, co-regulate IL6 expression together with that of genes associated to growth factor signaling, arguing for the hypothesis that common mechanism/s driven by EGFR ligands characterize both advanced-stage and LMP EOCs. Only advanced-stage EOCs appeared to be characterized by a scenario that involves genes which are so far associated with thrombosis and cardiovascular disease, thus suggesting that this pathway is implicated in the growth and/or spread of more aggressive tumors. We have discovered novel activated signaling pathways that drive the expression of IL6 and of co-regulated genes and are possibly involved in the pathobiology of EOCs. PMID:23889749

2013-01-01

314

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

Fischbach, H; Hoffmeister, H M; Hoffmeister, H E; Apitz, J; Schmidt, C

1982-01-01

315

Nonlocality in sequential correlation scenarios

NASA Astrophysics Data System (ADS)

As first shown by Popescu (1995 Phys. Rev. Lett. 74 2619), some quantum states only reveal their nonlocality when subjected to a sequence of measurements while giving rise to local correlations in standard Bell tests. Motivated by this manifestation of ‘hidden nonlocality’ we set out to develop a general framework for the study of nonlocality when sequences of measurements are performed. Similar to Gallego et al (2013 Phys. Rev. Lett. 109 070401) our approach is operational, i.e. the task is to identify the set of allowed operations in sequential correlation scenarios and define nonlocality as the resource that cannot be created by these operations. This leads to a characterization of sequential nonlocality that contains as particular cases standard nonlocality and hidden nonlocality.

Gallego, Rodrigo; Würflinger, Lars Erik; Chaves, Rafael; Acín, Antonio; Navascués, Miguel

2014-03-01

316

Supercritical Angle Fluorescence Correlation Spectroscopy

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

Ries, Jonas; Ruckstuhl, Thomas; Verdes, Dorinel; Schwille, Petra

2008-01-01

317

Counterion Correlations on Condensed Biopolymers

NASA Astrophysics Data System (ADS)

Like-charged polyelectrolytes condense into ordered phases in the presence of multivalent ions. The physical origin of the attractive interaction required for this condensation has been intensely debated, but no clear consensus has emerged, although counterion correlations appear to play a key role. In order to elucidate the nature of these interactions, we have performed structural measurements of condensed phases formed between multivalent ions and a range of rod-like polyelectrolytes, including cytoskeletal F-actin, and Fd and M13 filamentary virus particles.šDirect measurements of the counterion density and correlations in different condensed phases will be presented, along with the temperature dependence of these phases. This work was supported by NSF DMR-0071761, DOE DEFG02-91ER45439, the Beckman Young Investigator Program, and the Cystic Fibrosis Foundation.

Angelini, Tommy; Butler, John; Ho, James; Liang, Hongjun; Wong, Gerard

2002-03-01

318

Lessons in Fluctuation Correlation Spectroscopy

Molecular diffusion and transport processes are fundamental in physical, chemical, and biological systems. Current approaches to measuring molecular transport in cells and tissues based on perturbation methods, e.g., fluorescence recovery after photobleaching, are invasive; single-point fluctuation correlation methods are local; and single-particle tracking requires the observation of isolated particles for relatively long periods of time. We discuss here the detection of molecular transport by exploiting spatiotemporal correlations measured among points at large distances (>1 ?m). We illustrate the evolution of the conceptual framework that started with single-point fluorescence fluctuation analysis based on the transit of fluorescent molecules through a small volume of illumination. This idea has evolved to include the measurement of fluctuations at many locations in the sample using microscopy imaging methods. Image fluctuation analysis has become a rich and powerful technique that can be used to extract information about the spatial distribution of molecular concentration and transport in cells and tissues. PMID:21219151

Digman, Michelle A.; Gratton, Enrico

2012-01-01

319

Correlated continuous time random walks

Continuous time random walks impose a random waiting time before each particle jump. Scaling limits of heavy-tailed continuous time random walks are governed by fractional evolution equations. Space-fractional derivatives describe heavy-tailed jumps, and the time-fractional version codes heavy-tailed waiting times. This paper develops scaling limits and governing equations in the case of correlated jumps. For long-range dependent jumps, this leads

Mark M. Meerschaert; Erkan Nane; Yimin Xiao

2009-01-01

320

Quantum correlations and number theory

We study the spin-1\\/2 Heisenberg XXX antiferromagnet for which the spectrum of the Hamiltonian was found by Bethe in 1931. We study the probability of the formation of ferromagnetic string in the antiferromagnetic ground state, which we call emptiness formation probability P(n). This is the most fundamental correlation function. We prove that, for short strings, it can be expressed in

H. E. Boos; V. E. Korepin; Y Nishiyama; M. Shiroishi

2002-01-01

321

?? helicity from h+/- energy correlations

NASA Astrophysics Data System (ADS)

We report a measurement of the magnitude of the ?? helicity from ?-pair events taken with the CLEO detector at the CESR electron-positron storage ring. Events in which each ? undergoes the decay ?-->h?, with h a charged pion or kaon, are analyzed for energy correlations between the daughter hadrons, yielding \\|?h\\| = 1.03+/-0.06+/-0.04, with the first error statistical and the second systematic.

Coan, T. E.; Fadeyev, V.; Korolkov, I.; Maravin, Y.; Narsky, I.; Shelkov, V.; Staeck, J.; Stroynowski, R.; Volobouev, I.; Ye, J.; Artuso, M.; Efimov, A.; Frasconi, F.; Gao, M.; Goldberg, M.; He, D.; Kopp, S.; Moneti, G. C.; Mountain, R.; Schuh, S.; Skwarnicki, T.; Stone, S.; Viehhauser, G.; Xing, X.; Bartelt, J.; Csorna, S. E.; Jain, V.; Marka, S.; Freyberger, A.; Godang, R.; Kinoshita, K.; Lai, I. C.; Pomianowski, P.; Schrenk, S.; Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L. P.; Zhou, G. J.; Barish, B.; Chadha, M.; Chan, S.; Eigen, G.; Miller, J. S.; O'grady, C.; Schmidtler, M.; Urheim, J.; Weinstein, A. J.; Würthwein, F.; Asner, D. M.; Bliss, D. W.; Brower, W. S.; Masek, G.; Paar, H. P.; Sharma, V.; Gronberg, J.; Hill, T. S.; Kutschke, R.; Lange, D. J.; Menary, S.; Morrison, R. J.; Nelson, H. N.; Nelson, T. K.; Qiao, C.; Richman, J. D.; Roberts, D.; Ryd, A.; Witherell, M. S.; Balest, R.; Behrens, B. H.; Cho, K.; Ford, W. T.; Park, H.; Rankin, P.; Roy, J.; Smith, J. G.; Alexander, J. P.; Bebek, C.; Berger, B. E.; Berkelman, K.; Bloom, K.; Cassel, D. G.; Cho, H. A.; Coffman, D. M.; Crowcroft, D. S.; Dickson, M.; Drell, P. S.; Ecklund, K. M.; Ehrlich, R.; Elia, R.; Foland, A. D.; Gaidarev, P.; Galik, R. S.; Gittelman, B.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hopman, P. I.; Kandaswamy, J.; Katayama, N.; Kim, P. C.; Kreinick, D. L.; Lee, T.; Liu, Y.; Ludwig, G. S.; Masui, J.; Mevissen, J.; Mistry, N. B.; Ng, C. R.; Nordberg, E.; Ogg, M.; Patterson, J. R.; Peterson, D.; Riley, D.; Soffer, A.; Ward, C.; Athanas, M.; Avery, P.; Jones, C. D.; Lohner, M.; Prescott, C.; Yelton, J.; Zheng, J.; Brandenburg, G.; Briere, R. A.; Gao, Y. S.; Kim, D. Y.-J.; Wilson, R.; Yamamoto, H.; Browder, T. E.; Li, F.; Li, Y.; Rodriguez, J. L.; Bergfeld, T.; Eisenstein, B. I.; Ernst, J.; Gladding, G. E.; Gollin, G. D.; Hans, R. M.; Johnson, E.; Karliner, I.; Marsh, M. A.; Palmer, M.; Selen, M.; Thaler, J. J.; Edwards, K. W.; Bellerive, A.; Janicek, R.; Macfarlane, D. B.; McLean, K. W.; Patel, P. M.; Sadoff, A. J.; Ammar, R.; Baringer, P.; Bean, A.; Besson, D.; Coppage, D.; Darling, C.; Davis, R.; Hancock, N.; Kotov, S.; Kravchenko, I.; Kwak, N.; Anderson, S.; Kubota, Y.; Lattery, M.; Lee, S. J.; O'neill, J. J.; Patton, S.; Poling, R.; Riehle, T.; Savinov, V.; Smith, A.; Alam, M. S.; Athar, S. B.; Ling, Z.; Mahmood, A. H.; Severini, H.; Timm, S.; Wappler, F.; Anastassov, A.; Blinov, S.; Duboscq, J. E.; Fisher, K. D.; Fujino, D.; Fulton, R.; Gan, K. K.; Hart, T.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.; Spencer, M. B.; Sung, M.; Undrus, A.; Wanke, R.; Wolf, A.; Zoeller, M. M.; Nemati, B.; Richichi, S. J.; Ross, W. R.; Skubic, P.; Wood, M.; Bishai, M.; Fast, J.; Gerndt, E.; Hinson, J. W.; Menon, N.; Miller, D. H.; Shibata, E. I.; Shipsey, I. P.; Yurko, M.; Gibbons, L.; Johnson, S. D.; Kwon, Y.; Roberts, S.; Thorndike, E. H.; Jessop, C. P.; Lingel, K.; Marsiske, H.; Perl, M. L.; Schaffner, S. F.; Ugolini, D.; Wang, R.; Zhou, X.

1997-06-01

322

Multiparticle Bose-Einstein correlations

Multiparticle symmetrization effects are contributions to the spectra of\\u000aBose-symmetrized states which are not the product of pairwise correlations.\\u000aUsually they are neglected in particle interferometric calculations which aim\\u000aat determining the geometry of the boson emitting source from the measured\\u000amomentum distributions. Based on a method introduced by Zajc and Pratt, we give\\u000aa calculation of all multiparticle symmetrization

Urs Achim Wiedemann

1998-01-01

323

Genotypic-Phenotypic Correlative Studies

The CBRG is a co-sponsor of the Cooperative Family Registry for Colon Cancer, established to support genotypic-phenotpic-correlative studies. The necessity for elucidating the relationship between genotype and phenotype is becoming particularly important when detection methods uncover changes in the genomic DNA without knowing if the changes are causing changes in the phenotype or if the phenotype has an association with clinical outcome.

324

Correlates of trustworthiness for celebrities

The widespread use of celebrities as product endorsers and company spokesmen stimulated the authors to investigate what factors\\u000a underlie the credibility of these endorsers. Two studies were conducted in order to determine those attributes of a celebrity\\u000a which correlate most highly with trust. In Study I, students rated 33 celebrities, who were not product endorsers, on six\\u000a attributes: awareness, trust,

Hershey H. Friedman; Michael J. Santeramo; Anthony Traina

1978-01-01

325

Quasar variability: correlations with amplitude

The relation between quasar variability and parameters such as luminosity and redshift has been a matter of hot debate over the last few years with many papers on the subject. Any correlations which can be established will have a profound effect on models of quasar structure and evolution. The sample of quasars in ESO/SERC field 287 contains over 600 quasars in the range 0 quasar variability.

M. R. S. Hawkins

2000-02-18

326

Alzheimer's disease: a correlative study.

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

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

327

Quantumness of correlations and entanglement

Generalized measurement schemes on one part of bipartite states, which would leave the set of all separable states insensitive are explored here to understand quantumness of correlations in a more general perspecitve. This is done by employing linear maps associated with generalized projective measurements. A generalized measurement corresponds to a quantum operation mapping a density matrix to another density matrix, preserving its positivity, hermiticity and traceclass. The Positive Operator Valued Measure (POVM) -- employed earlier in the literature to optimize the measures of classical/quatnum correlations -- correspond to completely positive (CP) maps. The other class, the not completely positive (NCP) maps, are investigated here, in the context of measurements, for the first time. It is shown that that such NCP projective maps provide a new clue to the understanding the quantumness of correlations in a general setting. Especially, the separability-classicality dichotomy gets resolved only when both the classes of projective maps (CP and NCP) are incorporated as optimizing measurements. An explicit example of a separable state -- exhibiting non-zero quantumn discord when possible optimizing measurements are restricted to POVMs -- is re-examined with this extended scheme incorporating NCP projective maps to elucidate the power of this approach.

A. R. Usha Devi; A. K. Rajagopal; Sudha

2011-05-20

328

Correlated Temporal and Spectral Variability

NASA Technical Reports Server (NTRS)

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.

Swank, Jean H.

2007-01-01

329

Spatial Correlations in Attribute Communities

Community detection is an important tool for exploring and classifying the properties of large complex networks and should be of great help for spatial networks. Indeed, in addition to their location, nodes in spatial networks can have attributes such as the language for individuals, or any other socio-economical feature that we would like to identify in communities. We discuss in this paper a crucial aspect which was not considered in previous studies which is the possible existence of correlations between space and attributes. Introducing a simple toy model in which both space and node attributes are considered, we discuss the effect of space-attribute correlations on the results of various community detection methods proposed for spatial networks in this paper and in previous studies. When space is irrelevant, our model is equivalent to the stochastic block model which has been shown to display a detectability-non detectability transition. In the regime where space dominates the link formation process, most methods can fail to recover the communities, an effect which is particularly marked when space-attributes correlations are strong. In this latter case, community detection methods which remove the spatial component of the network can miss a large part of the community structure and can lead to incorrect results. PMID:22666361

Cerina, Federica; De Leo, Vincenzo; Barthelemy, Marc; Chessa, Alessandro

2012-01-01

330

Spatial correlations in attribute communities.

Community detection is an important tool for exploring and classifying the properties of large complex networks and should be of great help for spatial networks. Indeed, in addition to their location, nodes in spatial networks can have attributes such as the language for individuals, or any other socio-economical feature that we would like to identify in communities. We discuss in this paper a crucial aspect which was not considered in previous studies which is the possible existence of correlations between space and attributes. Introducing a simple toy model in which both space and node attributes are considered, we discuss the effect of space-attribute correlations on the results of various community detection methods proposed for spatial networks in this paper and in previous studies. When space is irrelevant, our model is equivalent to the stochastic block model which has been shown to display a detectability-non detectability transition. In the regime where space dominates the link formation process, most methods can fail to recover the communities, an effect which is particularly marked when space-attributes correlations are strong. In this latter case, community detection methods which remove the spatial component of the network can miss a large part of the community structure and can lead to incorrect results. PMID:22666361

Cerina, Federica; De Leo, Vincenzo; Barthelemy, Marc; Chessa, Alessandro

2012-01-01

331

Correlated genotypes in friendship networks

It is well known that humans tend to associate with other humans who have similar characteristics, but it is unclear whether this tendency has consequences for the distribution of genotypes in a population. Although geneticists have shown that populations tend to stratify genetically, this process results from geographic sorting or assortative mating, and it is unknown whether genotypes may be correlated as a consequence of nonreproductive associations or other processes. Here, we study six available genotypes from the National Longitudinal Study of Adolescent Health to test for genetic similarity between friends. Maps of the friendship networks show clustering of genotypes and, after we apply strict controls for population stratification, the results show that one genotype is positively correlated (homophily) and one genotype is negatively correlated (heterophily). A replication study in an independent sample from the Framingham Heart Study verifies that DRD2 exhibits significant homophily and that CYP2A6 exhibits significant heterophily. These unique results show that homophily and heterophily obtain on a genetic (indeed, an allelic) level, which has implications for the study of population genetics and social behavior. In particular, the results suggest that association tests should include friends’ genes and that theories of evolution should take into account the fact that humans might, in some sense, be metagenomic with respect to the humans around them. PMID:21245293

Fowler, James H.; Settle, Jaime E.; Christakis, Nicholas A.

2011-01-01

332

Study of Correlations in DNA Sequences

We present a method for unified statistical analysis of short and long range correlations between various nucleotides in genomic DNA strands. The approach is based on the mutual study of Fourier structure, factor spectra and pair correlation functions. The analysis of cross correlations in the different ranges of structural spectra permits identification of the main sources of correlations, namely, the

V. R. Chechetkin; A. Y. Turygin

1996-01-01

333

Blood flow tracking using optical correlation techniques

It has been previously shown that tracking small particle motion can be accomplished by tracking the speckle pattern it produces. The joint transform correlator and the Sandia National Laboratories (SNL) acoustooptic correlator that were used to track speckle motion are described. Results demonstrate that optical correlation is capable of tracking speckle with an accuracy comparable to digital methods. Optical correlation

N. Clark; M. K. Giles; S. H. Harrison; C. P. Hofer

1992-01-01

334

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

Ashraf, Alireza; Farahangiz, Siamak; Pakniat Jahromi, Bita; Setayeshpour, Nazanin; Nasseri, Ali

2014-01-01

335

Agar-based antifungal susceptibility testing is an attractive alternative to the microdilution method. We examined the correlation between the microdilution, E-test, and disk diffusion methods for posaconazole against Candida spp. A total of 270 bloodstream isolates of Candida spp. with a broad range of posaconazole MICs were tested using the CLSI M27-A2 method for microdilution, as well as the M-44A method and E-test methods for agar-based testing on Mueller-Hinton agar supplemented with 2% glucose and 0.5 ?g of methylene blue. MICs and inhibitory zone diameters at the prominent growth reduction endpoint were recorded at 24 and 48 h. The Candida isolates included Candida albicans (n = 124), C. parapsilosis (n = 44), C. tropicalis (n = 41), C. glabrata (n = 36), C. krusei (n = 20), C. lusitaniae (n = 3), and C. dubliniensis (n = 2). The overall concordance (i.e., the percentage of isolates within two dilutions) between the E-test and microdilution was 64.8% at 24 h and 82.6% at 48 h. When we considered an arbitrary breakpoint of ?1 ?g/ml, the agreement between the E-test and microdilution methods was 87.8% at 24 h and 93.0% at 48 h. The correlation of MICs with disk diffusion zone diameters was better for the E-test than the microdilution method. Zone correlation for diameters produced by the disks of two manufacturers was high, with a Pearson test value of 0.941 at 24 h. The E-test and microdilution MICs show good concordance and interpretative agreement. The disk diffusion zone diameters are highly reproducible and correlate well with both the E-test and the microdilution method, making agar-based methods a viable alternative to microdilution for posaconazole susceptibility testing. PMID:16757605

Sims, Charles R.; Paetznick, Victor L.; Rodriguez, Jose R.; Chen, Enuo; Ostrosky-Zeichner, Luis

2006-01-01

336

Correlation between Voronoi volumes in disc packings

We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction $\\phi_{\\rm avg}$ ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of $\\phi_{\\rm avg}$ and anti-correlations for $\\phi_{\\rm avg}>0.8277$. The spatial extent of the anti-correlation increases with $\\phi_{\\rm avg}$ while the position of the maximum of the anti-correlation and the extent of the positive correlation shrink with $\\phi_{\\rm avg}$. We conjecture that the onset of anti-correlation corresponds to dilatancy onset in this system.

Song-Chuan Zhao; Stacy Sidle; Harry L. Swinney; Matthias Schröter

2011-09-05

337

Iterative method for generating correlated binary sequences

NASA Astrophysics Data System (ADS)

We propose an efficient iterative method for generating random correlated binary sequences with a prescribed correlation function. The method is based on consecutive linear modulations of an initially uncorrelated sequence into a correlated one. Each step of modulation increases the correlations until the desired level has been reached. The robustness and efficiency of the proposed algorithm are tested by generating sequences with inverse power-law correlations. The substantial increase in the strength of correlation in the iterative method with respect to single-step filtering generation is shown for all studied correlation functions. Our results can be used for design of disordered superlattices, waveguides, and surfaces with selective transport properties.

Usatenko, O. V.; Melnik, S. S.; Apostolov, S. S.; Makarov, N. M.; Krokhin, A. A.

2014-11-01

338

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

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

339

Novelty filtered optical correlator using photorefractive crystal

NASA Technical Reports Server (NTRS)

We demonstrate a new optical correlator in which the correlation peak intensity is increased when the matched input object is moving. The basic configuration of the correlator is the same as a VanderLugt optical correlator consisting of a photorefractive crystal. The principal of this new correlator is based on the dynamic grating erasure property of photorefractive materials. The detail of this principle is described.

Liu, Duncan T. H.; Chao, Tien-Hsin; Cheng, Li-Jen

1992-01-01

340

Variable Selection through Correlation Sifting

NASA Astrophysics Data System (ADS)

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 ?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 ?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.

Huang, Jim C.; Jojic, Nebojsa

341

Star polymers in correlated disorder

We analyze the impact of a porous medium (structural disorder) on the scaling of the partition function of a star polymer immersed in a good solvent. We show that corresponding scaling exponents change if the disorder is long-range-correlated and calculate the exponents in the new universality class. A notable finding is that star and chain polymers react in qualitatively different manner on the presence of disorder: the corresponding scaling exponents increase for chains and decrease for stars. We discuss the physical consequences of this difference.

V. Blavats'ka; C. von Ferber; Yu. Holovatch

2007-11-23

342

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

Welker, Kelli L; Orkin, Joseph D; Ryan, Timothy M

2009-10-01

343

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

Welker, Kelli L; Orkin, Joseph D; Ryan, Timothy M

2009-01-01

344

Measurement and Correlation of Ambient VOCs in Windsor, Ontario, Canada and Detroit, Michigan, USA

NASA Astrophysics Data System (ADS)

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.

Miller, L. J.; You, H.; Xu, X.; Molaroni, S.; Lemke, L.; Weglicki, L.; Krouse, H.; Krajenta, R.

2009-05-01

345

PREFACE: Correlation Dynamics in Nuclei

NASA Astrophysics Data System (ADS)

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.

Suzuki, Toshio; Otsuka, Takaharu; Ichimura, Munetake

2005-01-01

346

The dynamics of correlated novelties

NASA Astrophysics Data System (ADS)

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.

Tria, F.; Loreto, V.; Servedio, V. D. P.; Strogatz, S. H.

2014-07-01

347

Dipolar correlations in liquid water.

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 400 K and 0.9 and 1.3 g/cm(3), but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (?) 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 ? 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. PMID:25173018

Zhang, Cui; Galli, Giulia

2014-08-28

348

Dipolar correlations in liquid water

NASA Astrophysics Data System (ADS)

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 400 K and 0.9 and 1.3 g/cm3, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (?) 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 ? 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.

Zhang, Cui; Galli, Giulia

2014-08-01

349

The dynamics of correlated novelties.

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

Tria, F; Loreto, V; Servedio, V D P; Strogatz, S H

2014-01-01

350

The Effect of Error Correlation on Interfactor Correlation in Psychometric Measurement

ERIC Educational Resources Information Center

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…

Westfall, Peter H.; Henning, Kevin S. S.; Howell, Roy D.

2012-01-01

351

Minor polar compounds of 88 extra virgin olive oils were analyzed by HPLC-DAD-MS (high-performance liquid chromatography-diode array detector-mass spectrometry) and by the Folin-Ciocalteu (FC) spectrophotometric method, to validate and evaluate, for olive oils, the linear association between FC and HPLC data. The Pearson correlation coefficients were calculated between HPLC and FC results. The highest, positive R were related with deacetoxyoleuropein aglycone (R = 0.93) and oleuropein aglycone (R = 0.93) as single compounds and with the sum of orthodiphenols (R = 0.94) and the sum of all compounds (R = 0.95), showing that both estimations of total phenols content are reliably correlated, regardless for the absolute contents and are independent of the relative composition of the phenolic fraction. On the other hand the HPLC quantifications of apigenin and lignans showed no significant correlation with FC. These results, supported also by principal component analysis, may suggest caution about the interpretation of FC results to compare olive oils with very different phenolic profiles. PMID:24405086

Alessandri, Stefano; Ieri, Francesca; Romani, Annalisa

2014-01-29

352

Aim. To determine whether there is a significant correlation between the optic nerve head (ONH) circulation determined by laser speckle flowgraphy (LSFG) and kidney function. Materials. Seventy-one subjects were investigated. The estimated glomerular filtration rate (GFR) and serum creatinine, cystatin C, and urinary albumin excretion were measured. The ONH circulation was determined by an analysis of the pulse wave of LSFG, and this parameter was named blowout time (BOT). Chronic kidney disease (CKD) was defined to be present when the estimated GFR was <60?mL/min per 1.73?m2. Pearson's correlation coefficients were used to determine the relationship between the BOT and the kidney function. We also examined whether there were significant differences in all parameters in patients with and without CKD. Results. BOT was significantly correlated with the level of creatinine (r = ?0.24, P = 0.04), the estimated GFR (r = 0.42, P = 0.0003), cystatin C (r = ?0.29, P = 0.01), and urinary albumin excretion (r = ?0.29, P = 0.01). The BOT level in subjects with CKD was significantly lower than that in subjects without CKD (P = 0.002). Conclusion. BOT in ONH by LSFG can detect the organ damage such as kidney dysfunction, CKD. PMID:24678413

Takahashi, Mao

2014-01-01

353

Objective To analyze possible correlations among tubular dentine cement penetration, adhesiveness and apical leakage in fillings performed with gutta percha and an endodontic cement based on epoxy amine resin. Material and Methods Sixty similar, extracted human mandibular central incisors were irrigated, instrumented and filled following the same protocol. First, apical leakage was quantified by fluid filtration tests. Then, these same specimens were sectioned for analysis of tubular dentine cement penetration and the middle thirds were submitted to push-out tests to analyze the adhesiveness of the fillings. Results In brief, the means and standard deviations with a confidence interval of 95% were as follows: tubular dentine cement penetration (8.875±4.540), adhesiveness (4.441±2.683) and apical leakage (0.318±0.215). The data were confronted using the Pearson's test (P>0.05), and it was possible to prove that there was no correlation between (1) tubular dentine cement penetration and apical leakage (r2: 0.08276), (2) tubular dentine cement penetration and adhesiveness (r2: -0.2412) and (3) adhesiveness and apical leakage (r2: 0.1340). Conclusion After analysis of these data, it could be observed that there exists no correlation among the variables analyzed in this study. PMID:24626245

MACHADO, Ricardo; da SILVA NETO, Ulisses Xavier; CARNEIRO, Everdan; FARINIUK, Luiz Fernando; WESTPHALEN, Vania Portela Ditzel; CUNHA, Rodrigo Sanches

2014-01-01

354

Viscosity-pressure correlation of liquids

NASA Astrophysics Data System (ADS)

A single correlation was obtained to predict Newtonian viscosity-pressure coefficients of mineral oils, resin and polymer blends, pure hydrocarbons, and nonhydrocarbons. The correlation has been tested for a temperature range from 0 to 135 C. The empirical correlation makes use of atmospheric-viscosity and density at the temperature of interest and viscosity-temperature property of the fluids. When the correlation was compared with other leading correlations, it was shown to require less physical-property data, apply to a wider range of chemical compositions, cover a wider range in fluidity, and provide greater accuracy. The correlation is presented in the form of a polynomial equation.

So, B. Y. C.; Klaus, E. E.

1980-10-01

355

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

Motunrayo Ibrahim, Fausat

2013-01-01

356

Purpose. Subjective tinnitus has different forms and degrees of severity. Many studies in the literature have assessed psychoacoustic characteristics of tinnitus but hardly any of them had focused on the association of audiological profile with onset duration and loudness perception. The aim of this study was to evaluate existence of any association between tinnitus loudness/onset duration and audiological profile to explain differences in prognosis. Method. Study design was prospective. The sample consisted of 26 subjects having tinnitus, which was divided into tinnitus and nontinnitus ears. Audiological profile included pure-tone audiometry, speech audiometry, tympanometry, acoustic reflex test, and auditory evoked potentials (early and middle latency). Unpaired t-test was applied to compare two subgroups. Correlation and association between tinnitus onset duration/loudness perception and audiological profile were also assessed by calculating Spearman's coefficient and Fischer exact value. Results. The two subgroups had significant differences for pure-tone and speech audiometry hearing thresholds. A significant association was observed between the high frequency/extended high frequency and tinnitus loudness/onset duration. Conclusion. The changes in hearing thresholds and auditory pathway are associated with an increase in tinnitus loudness and its onset duration. This knowledge would be helpful to differentiate between severity and chronicity of the patients for planning therapeutic management and predicting prognosis. PMID:24078882

Munjal, Sanjay K.; Panda, Naresh K.; Verma, Roshan K.

2013-01-01

357

Inferring correlations: From exemplars to categories.

Research and theorizing suggest a processing advantage of category-level correlations over exemplar-level correlations. That research has also shown that category-level correlations serve as a proxy for inferring exemplar-level correlations. For example, an individual may learn that the demand for a product category, like cheese, in one store predicts the demand for this category in another. The individual could then draw the unwarranted conclusion that the demand for an exemplar, like cheddar, would also predict the demand for this exemplar in the other store. This notion is supported by previous experiments demonstrating that the subjective exemplar-level correlation follows the implication of the category-level correlation. However, in virtually all previous experiments suggesting a processing advantage for category-level over exemplar-level correlations, the stimulus correlation at the category level was substantial, whereas the correlation at the exemplar level was weak. Here, we tested the hypothesis that individuals process the level that is most informative, either the exemplar or the category level. We presented participants with a zero correlation at the category level, but varied the correlation at the exemplar level. Participants presented with a zero correlation across exemplar products correctly reproduced a zero correlation across product categories. When presented with a substantial correlation at the exemplar level, however, they erroneously reproduced a similar correlation at the category level. These findings therefore imply that there is no general processing advantage for correlations at higher aggregation levels. Instead, individuals seemingly attend to the level that holds the most regular information. Findings are discussed regarding the role of covariation strength in correlation detection and use. PMID:24493021

Vogel, Tobias; Kutzner, Florian; Freytag, Peter; Fiedler, Klaus

2014-10-01

358

[Neurobiological correlates of EMDR therapy].

The EEGs in a group of ten subjects with major psychological trauma treated with EMDR and in ten controls have been registered both during the listening of the autobiographical narrative of the index trauma (script) and during a whole EMDR session. The EEGs have been performed again during the last EMDR session when patients were free of symptoms. During script listening a prevalent activation of the limbic regions corresponding to prefrontal and orbitofrontal cortex has been registered, being explained as the emotional arousal during trauma reliving at the symptomatic phase. The significant decrease of such activations during the late asymptomatic phase represents the neurobiological correlate of recovery. Moreover, the evidence of significant cortical activation in the parietal-temporo-occipital areas, during the last session, suggests a switch of the dominant electrical signal towards cortical areas with a prevalent cognitive function. PMID:22622274

Pagani, Marco; Lorenzo, Giorgio di; Verardo, Annarita; Nicolais, Giampaolo; Monaco, Leonardo; Niolu, Cinzia; Fernandez, Isabel; Siracusano, Alberto

2012-01-01

359

Are Quantum Correlations Genuinely Quantum?

NASA Astrophysics Data System (ADS)

It is shown that the probabilities for the spin singlet can be reproduced through classical resources, with no communication between the distant parties, by using merely shared (pseudo-)randomness. If the parties are conscious beings aware of both the hidden-variables and the random mechanism, then one has a conspiracy. If the parties are aware of only the random variables, they may be induced to believe that they are able to send instantaneous information to one another. It is also possible to reproduce the correlations at the price of reducing the detection efficiency. It is further demonstrated that the same probability decomposition could be realized through action-at-a-distance, provided it existed.

di Lorenzo, Antonio

2013-01-01

360

Are Quantum Correlations Genuinely Quantum?

NASA Astrophysics Data System (ADS)

It is shown that the probabilities for the spin singlet can be reproduced through classical resources, with no communication between the distant parties, by using merely shared (pseudo-)randomness. If the parties are conscious beings aware of both the hidden-variables and the random mechanism, then one has a conspiracy. If the parties are aware of only the random variables, they may be induced to believe that they are able to send instantaneous information to one another. It is also possible to reproduce the correlations at the price of reducing the detection efficiency. It is further demonstrated that the same probability decomposition could be realized through action-at-a-distance, provided it existed.

di Lorenzo, Antonio

2012-05-01

361

Behavioral analyses are a natural choice for understanding the wide-ranging behavioral consequences of racial stereotyping and prejudice. However, neuroimaging and electrophysiological research has recently considered the neural mechanisms that underlie racial categorization and the activation and application of racial stereotypes and prejudice, revealing exciting new insights. Work reviewed here points to the importance of neural structures previously associated with face processing, semantic knowledge activation, evaluation, and self-regulatory behavioral control, allowing for the specification of a neural model of race processing. We show how research on the neural correlates of race can serve to link otherwise disparate lines of evidence on the neural underpinnings of a broad array of social-cognitive phenomena, and consider implications for effecting change in race relations. PMID:19896410

Ito, Tiffany A.; Bartholow, Bruce D.

2009-01-01

362

CORRELATIONS IN CONFINED QUANTUM PLASMAS

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

DUFTY J W

2012-01-11

363

Correlating thalamocortical connectivity and activity

NASA Astrophysics Data System (ADS)

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.

da Fontoura Costa, Luciano; Sporns, Olaf

2006-07-01

364

Physiological correlates of mental workload

NASA Technical Reports Server (NTRS)

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.

Zacharias, G. L.

1980-01-01

365

Vibration analysis using digital correlation

NASA Technical Reports Server (NTRS)

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.

Gilbert, John A.; Lehner, David L.; Dudderar, T. Dixon; Matthys, Donald R.

1988-01-01

366

Investigation of correlation classification techniques

NASA Technical Reports Server (NTRS)

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.

Haskell, R. E.

1975-01-01

367

Quantum Correlations, Chaos and Information

NASA Astrophysics Data System (ADS)

Quantum chaos is the study of quantum systems whose classical description is chaotic. How does chaos manifest itself in the quantum world? In this spirit, we study the dynamical generation of entanglement as a signature of chaos in a system of periodically kicked coupled-tops, where chaos and entanglement arise from the same physical mechanism. The long-time entanglement as a function of the position of an initially localized wave packet very closely correlates with the classical phase space surface of section - it is nearly uniform in the chaotic sea, and reproduces the detailed structure of the regular islands. The uniform value in the chaotic sea is explained by the random state conjecture. As classically chaotic dynamics take localized distributions in phase space to random distributions, quantized versions take localized coherent states to pseudo-random states in Hilbert space. Such random states are highly entangled, with an average value near that of the maximally entangled state. For a map with global chaos, we derive that value based on new analytic results for the entropy of random states. For a mixed phase space, we use the Percival conjecture to identify a "chaotic subspace" of the Hilbert space. The typical entanglement, averaged over the unitarily invariant Haar measure in this subspace, agrees with the long-time averaged entanglement for initial states in the chaotic sea. In all cases the dynamically generated entanglement is that of a random complex vector, even though the system is time-reversal invariant, and the Floquet operator is a member of the circular orthogonal ensemble. Continuing on our journey to find the footprints of chaos in the quantum world, we explore quantum signatures of classical chaos by studying the rate of information gain in quantum tomography. The measurement record is obtained as a sequence of expectation values of a Hermitian operator evolving under repeated application of the Floquet operator of the quantum kicked top on a large ensemble of identical systems. We find an increase in the rate of information gain and hence higher fidelities in the process when the Floquet maps employed increase in chaoticity. We make predictions for the information gain using random matrix theory in the fully chaotic regime and show a remarkable agreement between the two. Finally we discuss how this approach can be used in general as a benchmark for information gain in an experimental implementation based on nonlinear dynamics of atomic spins measured weakly by the Faraday rotation of a laser probe. The last part of this thesis is devoted to the study of the nature of quantum correlations themselves. Quantum correlations are at the heart of the weirdness of quantum mechanics and at the same time serve as a resource for the potential benefits quantum information processing might provide. For example, Einstein described quantum entanglement as "spooky action at a distance". However, even entanglement does not fully capture the complete quantum character of a system. Quantum discord aims to fill this gap and captures essentially all the quantum correlations in a quantum state. There is a considerable interest in the research community about quantum discord, since there is evidence showing this very quantity as responsible for the exponential speed up of a certain class of quantum algorithms over classical ones. Now, an important question arises: Is discord just a mathematical construct or does it have a definable physical role in information processing? This thesis provides a link between quantum discord and an actual physical task involving communication between two parties. We present an operational interpretation of quantum discord based on the quantum state merging protocol. Quantum discord is the markup in the cost of quantum communication in the process of quantum state merging, if one discards relevant prior information. We further derive a quantitative relation between the yield of the fully quantum Slepian-Wolf protocol in the presence of noise and the quantum discord of

Madhok, Vaibhav

368

This talk explores the spin--1 correlators up to O(alpha_s) through a large NC resonance theory. The phenomenological analyses of this kind must take these corrections into account since they produce a larger impact than the first OPE condensates. It is also necessary to separate low and high energy regimes; fixing the parameters of the lightest multiplets through perturbative QCD arguments is unfair and introduces errors in the determination of the condensates and resonance parameters. This separation of regimes improves our understanding of the Minimal Hadronical Approximation. The study at O(alpha_s) already allows discerning between different hadronical models, where the Regge-like mass spectrum shows the best agreement to phenomenology.

J. J. Sanz-Cillero

2005-10-12

369

Correlated valence-bond states

NASA Astrophysics Data System (ADS)

We study generalizations of the singlet-sector amplitude-product (AP) states in the valence-bond basis of S=1/2 quantum spin systems. In the standard AP states, the weight of a tiling of the system into valence bonds (singlets of two spins) is a product of amplitudes depending on the length of the bonds. We here introduce correlated AP (CAP) states, in which the AP is further multiplied by factors depending on two bonds connected to a pair of sites (here nearest neighbors). While the standard AP states can describe a phase transition between an antiferromagnetic (Néel) state and a valence-bond solid (VBS) in one dimension (which we also study here), in two dimensions it cannot describe VBS order. With the CAP states, Néel-VBS transitions are realized as a function of some parameter describing the bond correlations. We here study such phase transitions of CAP wave functions on the square lattice. We find examples of direct first-order Néel-VBS transitions, as well as cases where there is an extended U(1) spin liquid phase intervening between the Néel and VBS states. In the latter case the transitions are continuous and we extract critical exponents and address the issue of a possible emergent U(1) symmetry in the near-critical VBS. We also consider variationally optimized CAP states for the standard Heisenberg model in one and two dimensions and the J-Q model in two dimensions, with the latter including four-spin interactions (Q) in addition to the Heisenberg exchange (J) and harboring VBS order for large Q/J. The optimized CAP states lead to significantly lower variational energies than the simple AP states for these models.

Lin, Yu-Cheng; Tang, Ying; Lou, Jie; Sandvik, Anders W.

2012-10-01

370

Percolation of secret correlations in a network

In this work, we explore the analogy between entanglement and secret classical correlations in the context of large networks—more precisely, the question of percolation of secret correlations in a network. It is known that ...

Raul, Garcia-Patron

371

Energy correlation functions for jet substructure

We show how generalized energy correlation functions can be used as a powerful probe of jet substructure. These correlation functions are based on the energies and pair-wise angles of particles within a jet, with (N?+?1)-point ...

Salam, Gavin P.

372

Use of correlation matrices in lattice QCD

This thesis explores the use of correlation matrices in analyzing Monte Carlo calculations from lattice quantum chromodynamics. Correlation matrices are a powerful tool for examining many problems in which significant ...

Lepzelter, David, 1981-

2004-01-01

373

2004 Photon Correlation and Scattering Conference

NASA Technical Reports Server (NTRS)

The Photon Correlation and Scattering (PCS) meeting welcomes all who are interested in the art and science of photon correlation and its application to optical scattering. The meeting is intended to enhance interactions between theory, applications, instrument design, and participants.

Meyer, William (Editor); Smart, Anthony (Editor); Wegdam, Gerard (Editor); Dogariu, Aristide (Editor); Carpenter, Bradley (Editor)

2004-01-01

374

Arousal and Anxiety Correlates of Gymnastic Performance

ERIC Educational Resources Information Center

Tests on a women's gymnastic team to explore correlation between arousal, anxiety, and performance, revealed limited relationships between performance and arousal/anxiety measures and indicated that gymnastic ability is the best correlate of gymnastic performance. (JD)

Basler, Marilyn L.; And Others

1976-01-01

375

Background In adults, heart rate recovery is a predictor of mortality, while in adolescents it is associated with cardio-metabolic risk factors. The aim of this study was to examine the relationship between body composition measures and heart rate recovery (HRR) after step test in Malaysian secondary school students. Methods In the Malaysian Health and Adolescents Longitudinal Research Team (MyHEART) study, 1071 healthy secondary school students, aged 13 years old, participated in the step test. Parameters for body composition measures were body mass index z-score, body fat percentage, waist circumference, and waist height ratio. The step test was conducted by using a modified Harvard step test. Heart rate recovery of 1 minute (HRR1min) and heart rate recovery of 2 minutes (HRR2min) were calculated by the difference between the peak pulse rate during exercise and the resting pulse rate at 1 and 2 minutes, respectively. Analysis was done separately based on gender. Pearson correlation analysis was used to determine the association between the HRR parameters with body composition measures, while multiple regression analysis was used to determine which body composition measures was the strongest predictor for HRR. Results For both gender groups, all body composition measures were inversely correlated with HRR1min. In girls, all body composition measures were inversely correlated with HRR2min, while in boys all body composition measures, except BMI z-score, were associated with HRR2min. In multiple regression, only waist circumference was inversely associated with HRR2min (p=0.024) in boys, while in girls it was body fat percentage for HRR2min (p=0.008). Conclusion There was an inverse association between body composition measurements and HRR among apparently healthy adolescents. Therefore, it is important to identify cardio-metabolic risk factors in adolescent as an early prevention of consequent adulthood morbidity. This reiterates the importance of healthy living which should start from young. PMID:24349388

Abu Hanifah, Redzal; Mohamed, Mohd. Nahar Azmi; Jaafar, Zulkarnain; Abdul Mohsein, Nabilla Al-Sadat; Jalaludin, Muhammad Yazid; Abdul Majid, Hazreen; Murray, Liam; Cantwell, Marie; Su, Tin Tin

2013-01-01

376

Criminal Cross Correlation Mining and Visualization

Criminals are creatures of habit and their crime activities are geospatially, temporally and thematically correlated. Discovering\\u000a these correlations is a core component of intelligence-led policing and allows for a deeper insight into the complex nature\\u000a of criminal behavior. A spatial bivariate correlation measure should be used to discover these patterns from heterogeneous\\u000a data types. We introduce a bivariate spatial correlation

Peter Phillips; Ickjai Lee

2009-01-01

377

Boundary correlation functions of integrable vertex models

NASA Astrophysics Data System (ADS)

We review our recent work on the boundary correlation functions of integrable vertex models on an N × N lattice with domain wall boundary conditions. Particularly considered is the six vertex model. The general expression of the boundary correlation functions is obtained for the six vertex model by use of the quantum inverse scattering method. We also comment on the potential application of the boundary correlation functions, and the relation between the boundary correlation functions for the nineteen vertex model.

Motegi, Kohei

2012-02-01

378

Long range correlations in branched polymers

NASA Astrophysics Data System (ADS)

We study the correlation functions in the branched polymer model. Although there are no correlations in the grand canonical ensemble, when looking at the canonical ensemble we find negative long range power like correlations. We propose that a similar mechanism explains the shape of recently measured correlation functions in the elongated phase of 4d simplicial gravity [B. de Bakker and J. Smit, Nucl. Phys. B 454 (1995) 343].

Bialas, Piotr

1996-02-01

379

Redshift distortions of galaxy correlation functions

To examine how peculiar velocities can affect the 2-, 3-, and 4-point correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We present the results as the correlation length r[sub 0] and power index [gamma] of the 2-point correlation, [anti [Xi

Fry, J.N. (Fermi National Accelerator Lab., Batavia, IL (United States) Florida Univ., Gainesville, FL (United States). Dept. of Physics); Gaztanaga, E. (Fermi National Accelerator Lab., Batavia, IL (United States) Oxford Univ. (United Kingdom). Dept. of Physics)

1993-05-12

380

Body Definition Based on Visuomotor Correlation

This work proposes a plausible approach for a humanoid robot to define its own body based on visuomotor correlation. The high correlation of motion between vision and proprioception informs the robot that a visually moving object is related to the motor function of its own body. When the robot finds a motor-correlated object during motor exploration, visuomotor cues such as

Ryo Saegusa; Giorgio Metta; Giulio Sandini

2012-01-01

381

Optimization of Correlated Responses of EDM Process

Electrical discharge machining (EDM) process has several important performance measures (responses), some of which are correlated. For example, material removal rate (MRR) and electrode wear rate (EWR) are highly correlated. No reported research work on EDM process has taken into consideration the possible correlation between the response variables while determining the optimal process conditions. Thus, the results achieved by the

Rina Chakravorty; Susanta Kumar Gauri; Shankar Chakraborty

2011-01-01

382

Optimization of Correlated Responses of EDM Process

Electrical discharge machining (EDM) process has several important performance measures (responses), some of which are correlated. For example, material removal rate (MRR) and electrode wear rate (EWR) are highly correlated. No reported research work on EDM process has taken into consideration the possible correlation between the response variables while determining the optimal process conditions. Thus, the results achieved by the

Rina Chakravorty; Susanta Kumar Gauri; Shankar Chakraborty

2012-01-01

383

Extremely Correlated Fermi Liquids B. Sriram Shastry

Extremely Correlated Fermi Liquids B. Sriram Shastry Physics Department, University of California the theory of an extremely correlated Fermi liquid with U ! 1. This liquid has an underlying auxiliary Fermi liquid Green's function that is further caparisoned by extreme correlations. The theory leads to two

California at Santa Cruz, University of

384

Strongly-correlated heterostructures Satoshi Okamoto

of electronic reconstruction by studying model heterostructures consisting of strongly-correlated systems promising areas of research in strongly- correlated electronic systems. In addition to its basic im. Future directions for research are also discussed. I. INTRODUCTION "Correlated-electron systems

Ahlers, Guenter

385

Approximation techniques in strongly correlated electron systems

This dissertation details the study and application of three approximation techniques for strongly correlated electron systems. These techniques are the dynamical mean field approximation (DMFA), dynamical cluster approximation (DCA) and cellular dynamical mean field theory (CDMFT). The DMFA is a local approximation in which electron-electron correlations are only dynamical in time and all non-local correlations in space are suppressed. This

Karan Aryanpour

2003-01-01

386

Scale evolution of double parton correlations

We review the effect of scale evolution on a number of different correlations in double parton scattering (DPS). The strength of the correlations generally decreases with the scale but at a rate which greatly varies between different types. Through studies of the evolution, an understanding of which correlations can be of experimental relevance in different processes and kinematical regions is obtained.

Tomas Kasemets

2014-11-17

387

Universal measurement of quantum correlations of radiation

A measurement technique is proposed which, in principle, allows one to observe the general space-time correlation properties of a quantized radiation field. Our method, called balanced homodyne correlation measurement, unifies the advantages of balanced homodyne detection with those of homodyne correlation measurements.

E. Shchukin; W. Vogel

2006-02-15

388

Statistical correlations of crime with arrests

NASA Astrophysics Data System (ADS)

Regression analysis shows that the overall crime rate correlates with the overall arrest rate. Violent crime only weakly correlates with the violent arrest rate, but strongly correlates with the property arrest rate. Contrary to common impressions, increasing arrest rates do not significantly increase loading on incarceration facilities.

Kuelling, Albert C.

1997-01-01

389

Economic and Educational Correlates of TIMSS Results

ERIC Educational Resources Information Center

The good knowledge of the correlates of educational achievement highlights the ways to the efficient use of economic and human capital in raising the efficiency of education. The present paper investigates the correlates and compares the values of the correlates for the Republic of Lithuania with the average international values. The data for the…

Mikk, Jaan

2005-01-01

390

Functional Multiple-Set Canonical Correlation Analysis

ERIC Educational Resources Information Center

We propose functional multiple-set canonical correlation analysis for exploring associations among multiple sets of functions. The proposed method includes functional canonical correlation analysis as a special case when only two sets of functions are considered. As in classical multiple-set canonical correlation analysis, computationally, the…

Hwang, Heungsun; Jung, Kwanghee; Takane, Yoshio; Woodward, Todd S.

2012-01-01

391

The Planet-Metallicity Correlation

NASA Astrophysics Data System (ADS)

We have recently carried out spectral synthesis modeling to determine Teff, logg, vsini, and [Fe/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K>30 m s-1 and orbital periods shorter than 4 yr. From this subset of stars, we determine that fewer than 3% of stars with -0.5<[Fe/H]<0.0 have Doppler-detected planets. Above solar metallicity, there is a smooth and rapid rise in the fraction of stars with planets. At [Fe/H]>+0.3 dex, 25% of observed stars have detected gas giant planets. A power-law fit to these data relates the formation probability for gas giant planets to the square of the number of metal atoms. High stellar metallicity also appears to be correlated with the presence of multiple-planet systems and with the total detected planet mass. This data set was examined to better understand the origin of high metallicity in stars with planets. None of the expected fossil signatures of accretion are observed in stars with planets relative to the general sample: (1) metallicity does not appear to increase as the mass of the convective envelopes decreases, (2) subgiants with planets do not show dilution of metallicity, (3) no abundance variations for Na, Si, Ti, or Ni are found as a function of condensation temperature, and (4) no correlations between metallicity and orbital period or eccentricity could be identified. We conclude that stars with extrasolar planets do not have an accretion signature that distinguishes them from other stars; more likely, they are simply born in higher metallicity molecular clouds. Based on observations obtained at Lick and Keck Observatories, operated by the University of California, and the Anglo-Australian Observatories.

Fischer, Debra A.; Valenti, Jeff

2005-04-01

392

Noise correlations in cosmic microwave background experiments

NASA Technical Reports Server (NTRS)

Many analysis of microwave background experiments neglect the correlation of noise in different frequency of polarization channels. We show that these correlations, should they be present, can lead to serve misinterpretation of an experiment. In particular, correlated noise arising from either electronics or atmosphere may mimic a cosmic signal. We quantify how the likelihood function for a given experiment varies with noise correlation, using both simple analytic models and actual data. For a typical microwave background anisotropy experiment, noise correlations at the level of 1% of the overall noise can seriously reduce the significance of a given detection.

Dodelson, Scott; Kosowsky, Arthur; Myers, Steven T.

1995-01-01

393

Exponential Decay of Correlations Implies Area Law

NASA Astrophysics Data System (ADS)

We prove that a finite correlation length, i.e., exponential decay of correlations, implies an area law for the entanglement entropy of quantum states defined on a line. The entropy bound is exponential in the correlation length of the state, thus reproducing as a particular case Hastings's proof of an area law for groundstates of 1D gapped Hamiltonians. As a consequence, we show that 1D quantum states with exponential decay of correlations have an efficient classical approximate description as a matrix product state of polynomial bond dimension, thus giving an equivalence between injective matrix product states and states with a finite correlation length.

Brandão, Fernando G. S. L.; Horodecki, Micha?

2014-11-01

394

Nature of light correlations in ghost imaging

We investigate the nature of correlations in Gaussian light sources used for ghost imaging. We adopt methods from quantum information theory to distinguish genuinely quantum from classical correlations. Combining a microscopic analysis of speckle-speckle correlations with an effective coarse-grained description of the beams, we show that quantum correlations exist even in `classical'-like thermal light sources, and appear relevant for the implementation of ghost imaging in the regime of low illumination. We further demonstrate that the total correlations in the thermal source beams effectively determine the quality of the imaging, as quantified by the signal-to-noise ratio.

Sammy Ragy; Gerardo Adesso

2012-08-28

395

Behavior of Quantum Correlations under Local Noise

We characterize the behavior of quantum correlations under the influence of local noisy channels. Intuition suggests that such noise should be detrimental for quantumness. When considering qubit systems, we show for which channel this is indeed the case: the amount of quantum correlations can only decrease under the action of unital channels. However, non-unital channels (e.g. such as dissipation) can create quantum correlations for some initially classical state. Furthermore, for higher-dimensional systems even unital channels may increase the amount of quantum correlations. Thus, counterintuitively, local decoherence can generate quantum correlations.

Alexander Streltsov; Hermann Kampermann; Dagmar Bruß

2011-06-10

396

Skeletal muscle metabolism is impaired in disorders like diabetes mellitus or peripheral vascular disease. The skeletal muscle echo planar imaging (EPI) signal (S(EPI) ) and its relation to energy metabolism are still debated. Localised ³¹P MRS and S(EPI) data from gastrocnemius medialis of 19 healthy subjects were combined in one scanning session to study direct relationships between phosphocreatine (PCr), pH kinetics and parameters of T?? time courses. Dynamic spectroscopy (semi-LASER) and EPI were performed immediately before, during and after 5?min of plantar flexions. Data were acquired in a 7?T MR scanner equipped with a custom-built ergometer and a dedicated ³¹P/¹H radio frequency (RF) coil array. Using a form-fitted multi-channel ³¹P/¹H coil array resulted in high signal-to-noise ratio (SNR). PCr and pH in the gastrocnemius medialis muscle were quantified from each ³¹P spectrum, acquired every 6?s. During exercise, SEPI (t) was found to be a linear function of tissue pH(t) (cross-correlation r?=?-0.85?±?0.07). Strong Pearson's correlations were observed between post exercise time-to-peak (TTP) of SEPI and (a) the time constant of PCr recovery ?PCr?recovery (r?=?0.89, p?correlations of the skeletal muscle SEPI during exercise and tissue pH time courses and of post exercise SEPI and parameters of energy metabolism were observed. In conclusion, a tight coupling between skeletal muscle metabolic activity and tissue T?? signal weighting, probably induced by osmotically driven water shift, exists and can be measured non-invasively, using NMR at 7?T. PMID:24610788

Schmid, Albrecht Ingo; Schewzow, Kiril; Fiedler, Georg Bernd; Goluch, Sigrun; Laistler, Elmar; Wolzt, Michael; Moser, Ewald; Meyerspeer, Martin

2014-05-01

397

Neural correlates of hysterical blindness.

The neural mechanisms underlying conversion disorders such as hysterical blindness are at present unknown. Typically, patients are diagnosed through exclusion of neurological disease and the absence of pathologic neurophysiological diagnostic findings. Here, we investigate the neural basis of this disorder by combining electrophysiological (event-related potentials) and hemodynamic measures (functional magnet resonance tomography) in a patient with hysterical blindness before and after successful treatment. Importantly, the blindness was limited to the left upper and right lower visual quadrant offering the possibility to use the other 2 sighted quadrants as controls. While the functional magnetic resonance imaging activations were normal for visual stimulation electrophysiological indices of visual processing were modulated in a specific manner. Before treatment, the amplitude of the N1 event-related potentials component had smaller amplitudes for stimuli presented in the blind quadrants of the visual field. Following successful treatment the N1 component elicited by stimuli presented in formerly blind quadrants had a normal distribution without any amplitude differences between the 4 quadrants. The current findings point out that dissociative disorders such as hysterical blindness may have neurophysiological correlates. Furthermore, the observed neurophysiological pattern suggests an involvement of attentional mechanisms in the neural basis hysterical blindness. PMID:21368085

Schoenfeld, Mircea Ariel; Hassa, Thomas; Hopf, Jens-Max; Eulitz, Carsten; Schmidt, Roger

2011-10-01

398

Structural Correlates of Prospective Memory

Prospective memory (PM) includes the encoding and maintenance of an intention, and the retrieval and execution of this intention at the proper moment in the future. The present study expands upon previous behavioral, electrophysiological, and functional work by examining the association between grey matter volume and PM. Estimates of grey matter volume in theoretically relevant regions of interest (prefrontal, parietal, and medial temporal) were obtained in conjunction with performance on two PM tasks in a sample of 39 cognitively normal and very mildly demented older adults. The first PM task, termed focal in the literature, is supported by spontaneous retrieval of the PM intention whereas the second, termed non-focal, relies on strategic monitoring processes for successful intention retrieval. A positive relationship was observed between medial temporal volume and accuracy on the focal PM task. An examination of medial temporal lobe subregions revealed that this relationship was strongest for the hippocampus, which is considered to support spontaneous memory retrieval. There were no significant structure-behavior associations for the non-focal PM task. These novel results confirm a relationship between behavior and underlying brain structure proposed by the multiprocess theory of PM, and extend findings on cognitive correlates of medial temporal lobe integrity. PMID:21982698

Gordon, Brian A; Shelton, Jill T; Bugg, Julie M; McDaniel, Mark A; Head, Denise

2011-01-01

399

Hedging with a correlated asset

NASA Astrophysics Data System (ADS)

Hedging a contingent claim with an asset which is not perfectly correlated with the underlying asset results in unhedgeable residual risk. Even if the residual risk is considered diversifiable, the option writer is faced with the problem of uncertainty in the estimation of the drift rates of the underlying and the hedging instrument. If the residual risk is not considered diversifiable, then this risk can be priced using an actuarial standard deviation principle in infinitesimal time. In both cases, these models result in the same nonlinear partial differential equation (PDE). A fully implicit, monotone discretization method is developed for solution of this pricing PDE. This method is shown to converge to the viscosity solution. Certain grid conditions are required to guarantee monotonicity. An algorithm is derived which, given an initial grid, inserts a finite number of nodes in the grid to ensure that the monotonicity condition is satisfied. At each timestep, the nonlinear discretized algebraic equations are solved using an iterative algorithm, which is shown to be globally convergent. Monte Carlo hedging examples are given to illustrate the profit and loss distribution at the expiry of the option.

Windcliff, H.; Wang, J.; Forsyth, P. A.; Vetzal, K. R.

2007-03-01

400

Performance highlights of the ALMA correlators

NASA Astrophysics Data System (ADS)

Two large correlators have been constructed to combine the signals captured by the ALMA antennas deployed on the Atacama Desert in Chile at an elevation of 5050 meters. The Baseline correlator was fabricated by a NRAO/European team to process up to 64 antennas for 16 GHz bandwidth in two polarizations and another correlator, the Atacama Compact Array (ACA) correlator, was fabricated by a Japanese team to process up to 16 antennas. Both correlators meet the same specifications except for the number of processed antennas. The main architectural differences between these two large machines will be underlined. Selected features of the Baseline and ACA correlators as well as the main technical challenges met by the designers will be briefly discussed. The Baseline correlator is the largest correlator ever built for radio astronomy. Its digital hybrid architecture provides a wide variety of observing modes including the ability to divide each input baseband into 32 frequency-mobile sub-bands for high spectral resolution and to be operated as a conventional 'lag' correlator for high time resolution. The various observing modes offered by the ALMA correlators to the science community for 'Early Science' are presented, as well as future observing modes. Coherently phasing the array to provide VLBI maps of extremely compact sources is another feature of the ALMA correlators. Finally, the status and availability of these large machines will be presented.

Baudry, Alain; Lacasse, Richard; Escoffier, Ray; Webber, John; Greenberg, Joseph; Platt, Laurence; Treacy, Robert; Saez, Alejandro F.; Cais, Philippe; Comoretto, Giovanni; Quertier, Benjamin; Okumura, Sachiko K.; Kamazaki, Takeshi; Chikada, Yoshihiro; Watanabe, Manabu; Okuda, Takeshi; Kurono, Yasutake; Iguchi, Satoru

2012-09-01

401

Correlates of depression in bipolar disorder.

We analyse time series from 100 patients with bipolar disorder for correlates of depression symptoms. As the sampling interval is non-uniform, we quantify the extent of missing and irregular data using new measures of compliance and continuity. We find that uniformity of response is negatively correlated with the standard deviation of sleep ratings (? = -0.26, p = 0.01). To investigate the correlation structure of the time series themselves, we apply the Edelson-Krolik method for correlation estimation. We examine the correlation between depression symptoms for a subset of patients and find that self-reported measures of sleep and appetite/weight show a lower average correlation than other symptoms. Using surrogate time series as a reference dataset, we find no evidence that depression is correlated between patients, though we note a possible loss of information from sparse sampling. PMID:24352942

Moore, Paul J; Little, Max A; McSharry, Patrick E; Goodwin, Guy M; Geddes, John R

2014-02-01

402

NASA Astrophysics Data System (ADS)

This paper describes a new method to distinguish river terrace levels based on clast hardness and degree of weathering measured with an Equotip hardness tester. The technique was applied to a series of terraces on the Miño River in the northwestern Iberian Peninsula, where the lack of suitable material, high degree of weathering, and intense iron cementation precluded routine dating. Detailed mapping demonstrated that terrace sediments occupy a range of altitudes that make assignment to a specific terrace, and/or correlation between levels, difficult. Statistical analysis of the Equotip hardness data from quartzite clasts using k-means clustering allowed four probable terrace levels to be identified; a series of t-tests generally supported these groupings. A fifth, lowermost terrace level, was not included in the analysis because of limited exposure above a reservoir. Clast hardness and degree of terrace weathering were generally consistent with progressive river downcutting. The occurrence of faulted sediments, however, suggested that terrace elevations were modified locally by post-depositional tectonic movements, which may explain why probable younger terraces in some sectors of the Miño River are at higher elevations than older terraces in adjacent sectors. The Equotip tester helped to resolve stratigraphic uncertainties and to assign deposits to specific terrace levels and was found to be a useful tool to distinguish and correlate river terraces.

Alberti, Augusto Pérez; Gomes, Alberto; Trenhaile, Alan; Oliveira, Maria; Horacio, Jesus

2013-06-01

403

We reconstruct long-term vegetation/paleoclimatic trends, spanning the last 18 million years, in Alaska. Yukon and far western Northwest Territories. Twenty-one average percentage spectra for pollen and spores are assembled from eight surface/subsurface sections. The sections are dated independently or by correlation. Pollen and spore ratios indicate the direction of change in vegetation and climatic parameters growing season temperature (T(est)), tree canopy density (C(est)) and paludification at study sites (P(est)). A global warm peak ca. 15 Ma is shown by the abundance of thermophilous taxa, including Fagus and Quercus. A temperature decline immediately following 15 Ma parallels climatic reconstructions based on marine oxygen isotopes. Subsequent declines correlate to the Messinian event and the onset of late Pliocene Pleistocene glaciation. After 7 Ma herbs and shrubs become more important elements of the palynological assemblages, suggesting a more continental, colder/drier climate. However, a late Pliocene warm interval is evident. Vegetation/climatic changes during the early to late Miocene show synchrony with, and are most economically attributable to, global events. After 7 Ma, vegetation/climate change is attributed primarily to latest Miocene-to-Pleistocene uplift of the Alaska Range and St. Elias Mrs. The continuing influence of global climatic patterns is shown in the late Pliocene warm interval, despite uplift to the south. The opening of the Bering Strait ca. 3 Ma may have moderated the climate in the study area.

White, J. M.; Ager, T. A.; Adam, D. P.; Leopold, E. B.; Liu, G.; Jette, H.; Schweger, C. E.

1997-01-01

404

Livestock operations are known to harbor elevated levels of antibiotic resistance genes (ARGs) that may pose a threat to public health. Broiler feedlots may represent an important source of ARGs in the environment. However, the prevalence and dissemination mechanisms of various types of ARGs in the environment of broiler feedlots have not previously been identified. We examined the occurrence, abundance and variation of ARGs conferring resistance to chloramphenicols, sulfonamides and tetracyclines in the environments of two representative types of broiler feedlots (free range and indoor) by quantitative PCR, and assessed their dissemination mechanisms. The results showed the prevalence of various types of ARGs in the environmental samples of the broiler feedlots including manure/litter, soil, sediment, and water samples, with the first report of five chloramphenicol resistance genes (cmlA, floR, fexA, cfr, and fexB) in broiler feedlots. Overall, chloramphenicol resistance genes and sulfonamides sul genes were more abundant than tetracyclines tet genes. The ARG abundances in the samples from indoor boiler feedlots were generally different to the free range feedlots, suggesting the importance of feeding operations in ARG dissemination. Pearson correlation analysis showed significant correlations between ARGs and mobile genetic element genes (int1 and int2), and between the different classes of ARGs themselves, revealing the roles of horizontal gene transfer and coselection for ARG dissemination in the environment. Further regression analysis revealed that fexA, sul1 and tetW could be reliable indicator genes to surrogate anthropogenic sources of ARGs in boiler feedlots (correlations of fexA, sul1 and tetW to all ARGs: R = 0.95, 0.96 and 0.86, p < 0.01). Meanwhile, significant correlations were also identified between indicator ARGs and their corresponding antibiotics. In addition, some ARGs were significantly correlated with typical metals (e.g., Cu, Zn, and As with fexA, fexB, cfr, sul1, tetW, tetO, tetS: R = 0.52-0.71) and some environmental parameters (e.g., TOC, TN, TP, NH3-N with fexA, fexB, cfr, sul1, tetW, tetO, tetQ, tetS: R = 0.53-0.87) (p < 0.01). Further redundancy analysis demonstrated that the distribution and transportation of ARGs from the boiler feedlots to the receiving environments were correlated with environmental variables. The findings highlight the contribution of some chemicals such as antibiotics and metals to the development of ARGs in broiler feedlots environments; and the observed ARG dissemination mechanism in the broiler feedlots facilitates the development of effective mitigation measures. PMID:25338275

He, Liang-Ying; Liu, You-Sheng; Su, Hao-Chang; Zhao, Jian-Liang; Liu, Shuang-Shuang; Chen, Jun; Liu, Wang-Rong; Ying, Guang-Guo

2014-11-18

405

Objective To assess perfusion patterns on a dual-energy pulmonary CT angiography (DECTA) of pulmonary hypertension (PHT) with variable causes and to assess whether the extent of perfusion defect can be used in the severity assessment of PHT. Materials and Methods Between March 2007 and February 2011, DECTA scans of 62 consecutive patients (24 men, 38 women; mean age, 58.5 ± 17.3 [standard deviation] years; range, 19-87 years) with PHT were retrospectively included with following inclusion criteria; 1) absence of acute pulmonary thromboembolism, 2) maximal velocity of tricuspid regurgitation jet (TR Vmax) above 3 m/s on echocardiography performed within one week of the DECTA study. Perfusion patterns of iodine map were divided into normal (NL), diffuse heterogeneously decreased (DH), multifocal geographic and multiple peripheral wedging patterns. The extent of perfusion defects (PD), the diameter of main pulmonary artery (MPA) and the ratio of ascending aorta diameter/MPA (aortopulmonary ratio, APR) were measured. Pearson correlation analysis was performed between TR Vmax on echocardiography and CT imaging parameters. Results Common perfusion patterns of primary PHT were DH (n = 15) and NL (n = 12). The perfusion patterns of secondary PHT were variable. On the correlation analysis, in primary PHT, TR Vmax significantly correlated with PD, MPA and APR (r = 0.52, r = 0.40, r = -0.50, respectively, all p < 0.05). In secondary PHT, TR Vmax significantly correlated with PD and MPA (r = 0.38, r = 0.53, respectively, all p < 0.05). Conclusion Different perfusion patterns are observed on DECTA of PHT according to the causes. PD and MPA are significantly correlated with the TR Vmax. PMID:24642727

Kim, Eun Young; Oh, Sang Young; Lee, Choong Wook; Hwang, Hye Jeon; Lee, Sang Min; Lee, Young Kyung

2014-01-01

406

Topics in strongly correlated electrons

NASA Astrophysics Data System (ADS)

The thesis is a collection of three topics connected together by the common themes of strong interactions, magnetism and quantum phases, such as the Aharonov-Bohm or Berry phase. The first part of the present dissertation discusses the possibility of examining microscopic origins of magnetism in strongly interacting systems by exploiting the setting of ultra-cold atomic gases in optical lattices. We discuss signatures of correlation in the trap, and propose an experiment to measure the phase diagram of itinerant magnetism directly. The second part focuses on the exotic phase of matter exhibiting the Fractional Quantum Hall Effect, which emerges when interacting particles are placed in a very strong magnetic field. We propose a trial ground state wave-function and prove that it is the unique highest density ground state of a well-motivated pseudo-potential Hamiltonian. The exchange statistics of quasiparticles are shown to be exotic, and overlaps with results of exact diagonalization are also discussed. The final part of the thesis studies frustrated magnetic systems, in which competing forces cannot not be satisfied simultaneously, doped with electrons. The interplay of frustration and itinerant behavior generates Berry phases associated with charge transport. We study the effects of these phases on electronic behavior, as well as the effect electrons have on the underlying magnetic textures. In the quasi-classical limit, we conjecture a field-driven metal-insulator transition, and discuss persistent currents arising in ground states selected by the presence of charge. In the quantum regime we derive the full Hamiltonian and discuss small fluctuations about the classical results.

Berdnikov, Ilya

407

Electrophysiological correlates of Complement Coercion

This study examined the electrophysiological correlates of complement coercion. Event-related potentials (ERPs) were measured as participants read and made acceptability judgments about plausible coerced sentences, plausible non-coerced sentences, and highly implausible animacy violated sentences (“The journalist began/wrote/astonished the article before his coffee break”). Relative to non-coerced complement nouns, the coerced nouns evoked an N400 effect. This effect was not modulated by the number of possible activities implied by the coerced nouns (e.g. began reading the article; began writing the article), and did not differ in either magnitude or scalp distribution from the N400 effect evoked by the animacy violated complement nouns. We suggest that the N400 modulation to both coerced and the animacy violated complement nouns reflected different types of mismatches between the semantic restrictions of the verb and the semantic properties of the incoming complement noun. This is consistent with models holding that a verb’s semantic argument structure is represented and stored at a distinct level from its syntactic argument structure. Unlike the coerced complement noun, the animacy violated nouns also evoked a robust P600 effect, which may have been triggered by the judgments of the highly implausible (syntactically-determined) meanings of the animacy violated propositions. No additional ERP effects were seen in the coerced sentences until the sentence-final word which, relative to sentence-final words in the non-coerced sentences, evoked a sustained anteriorly-distributed positivity. We suggest that this effect reflected delayed attempts to retrieve the specific event(s) implied by coerced complement nouns. PMID:19702471

Kuperberg, Gina R.; Choi, Arim; Cohn, Neil; Paczynski, Martin; Jackendoff, Ray

2011-01-01

408

Objective The aim of this study was to correlate the apparent diffusion coefficient (ADC) value of breast cancer with prognostic factors. Methods 335 patients with invasive ductal carcinoma not otherwise specified (IDC NOS) and ductal carcinoma in situ (DCIS) who underwent breast MRI with diffusion-weighted imaging were included in this study. ADC of breast cancer was calculated using two b factors (0 and 1000 s mm–2). Mean ADCs of IDC NOS and DCIS were compared and evaluated. Among cases of IDC NOS, mean ADCs were compared with lymph node status, size and immunochemical prognostic factors using Student's t-test. ADC was also correlated with histological grade using the Kruskal–Wallis test. Results Mean ADC of IDC NOS was significantly lower than that of DCIS (p<0.001). However, the mean ADC of histological grade of IDC NOS was not significantly different (p=0.564). Mean ADC of oestrogen receptor (ER)-positive or progesterone receptor (PR)-positive cancer was significantly lower than that of ER-negative or PR-negative cancer (p=0.003 vs p=0.032). Mean ADC of Ki-67 index-positive cancer was significantly lower than that of Ki-67 index-negative cancer (p=0.028). Mean ADC values of cancers with increased microvascular density (MVD) were significantly lower than those of cancer with no MVD increase (p=0.009). No correlations were observed between mean ADC value and human growth factor receptor 2 expression, tumour size and lymph node metastasis. Conclusion Low ADC value was correlated with positive expression of ER, PR, increased Ki-67 index, and increased MVD of breast cancer. PMID:22128125

Choi, S Y; Chang, Y-W; Park, H J; Kim, H J; Hong, S S; Seo, D Y

2012-01-01

409

Correlations in optically-controlled quantum emitters

We address the problem of optically controlling and quantifying the dissipative dynamics of quantum and classical correlations in a set-up of individual quantum emitters under external laser excitation. We show that both types of correlations, the former measured by the quantum discord, are present in the system's evolution even though the emitters may exhibit an early stage disentanglement. In the absence of external laser pumping,we demonstrate analytically, for a set of suitable initial states, that there is an entropy bound for which quantum discord and entanglement of the emitters are always greater than classical correlations, thus disproving an early conjecture that classical correlations are greater than quantum correlations. Furthermore, we show that quantum correlations can also be greater than classical correlations when the system is driven by a laser field. For scenarios where the emitters' quantum correlations are below their classical counterparts, an optimization of the evolution of the quantum correlations can be carried out by appropriately tailoring the amplitude of the laser field and the emitters' dipole-dipole interaction. We stress the importance of using the entanglement of formation, rather than the concurrence, as the entanglement measure, since the latter can grow beyond the total correlations and thus give incorrect results on the actual system's degree of entanglement.

Cristian E. Susa; John H. Reina

2011-12-19

410

Fraction of isospectral states exhibiting quantum correlations

For several types of correlations: mixed-state entanglement in systems of distinguishable particles, particle entanglement in systems of indistinguishable bosons and fermions and non-Gaussian correlations in fermionic systems we estimate the fraction of non-correlated states among the density matrices with the same spectra. We prove that for the purity exceeding some critical value (depending on the considered problem) fraction of non-correlated states tends to zero exponentially fast with the dimension of the relevant Hilbert space. As a consequence a state randomly chosen from the set of density matrices possessing the same spectra is asymptotically a correlated one. To prove this we developed a systematic framework for detection of correlations via nonlinear witnesses.

Micha? Oszmaniec; Marek Ku?

2013-12-27

411

Correlations in the Monte Carlo Glauber model

NASA Astrophysics Data System (ADS)

Event-by-event fluctuations of observables are often modeled using the Monte Carlo Glauber model, in which the energy is initially deposited in sources associated with wounded nucleons. In this paper, we analyze in detail the correlations between these sources in proton-nucleus and nucleus-nucleus collisions. There are correlations arising from nucleon-nucleon correlations within each nucleus, and correlations due to the collision mechanism, which we dub twin correlations. We investigate this new phenomenon in detail. At the Brookhaven Relativistic Heavy Ion Collider and CERN Large Hadron Collider energies, correlations are found to have modest effects on size and eccentricity fluctuations, such that the Glauber model produces to a good approximation a collection of independent sources.

Blaizot, Jean-Paul; Broniowski, Wojciech; Ollitrault, Jean-Yves

2014-09-01

412

Angular correlations and high energy evolution

We address the question of to what extent JIMWLK evolution is capable of taking into account angular correlations in a high energy hadronic wave function. Our conclusion is that angular (and indeed other) correlations in the wave function cannot be reliably calculated without taking into account Pomeron loops in the evolution. As an example we study numerically the energy evolution of angular correlations between dipole scattering amplitudes in the framework of the large N{sub c} approximation to JIMWLK evolution (the 'projectile dipole model'). Target correlations are introduced via averaging over an (isotropic) ensemble of anisotropic initial conditions. We find that correlations disappear very quickly with rapidity even inside the saturation radius. This is in accordance with our physical picture of JIMWLK evolution. The actual correlations inside the saturation radius in the target QCD wave function, on the other hand, should remain sizable at any rapidity.

Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, Connecticut 06269-3046 (United States); Lublinsky, Michael [Physics Department, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, Connecticut 06269-3046 (United States)

2011-11-01

413

[Purpose] This study examined the correlation between the muscle activities and joint angle of the hip and knee according to the changes in stance width during a lifting task. [Subjects and Methods] The subjects of this study were 15 healthy students. A three-dimensional motion analyzer (SMART-E, BTS, Italy) was used to measure the joint angles of hip and knee during lifting. An 8-channel electromyograph (8-EMG) (Pocket EMG, BTS, Italy) was used to measure muscle activities of the erector spinae, gluteus maximus, rectus femoris, and tibialis anterior during lifting. The collected data were analyzed using the Pearson-test and SPSS 18.0. [Result] The muscle activity of the tibialis anterior was significantly decreased by increasing the stance width (r= ?0.285). Muscle activity of the erector spinae was significantly decreased by increasing the knee angle (r= ?0.444). The muscle activity of the gluteus maximus was significantly increased by increasing the muscle activity of the tibialis anterior (r= 0.295). [Conclusion] Efficient lifting is possible when stance width and knee flexion are increased, which results in reduced muscle activity of the tibialis anterior and the erector spinae. Lifting is facilitated when the muscle activities of the gluteus maximus and tibialis anterior are correlated. PMID:24259908

Yoon, Jung-Gyu

2013-01-01

414

A novel peak alignment algorithm using a distance and spectrum correlation optimization (DISCO) method has been developed for two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC/TOF-MS)-based metabolomics. This algorithm uses the output of the instrument control software, ChromaTOF, as its input data. It detects and merges multiple peak entries of the same metabolite into one peak entry in each input peak list. After a z-score transformation of metabolite retention times, DISCO selects landmark peaks from all samples based on both two-dimensional retention times and mass spectrum similarity of fragment ions measured by Pearson's correlation coefficient. A local linear fitting method is employed in the original two-dimensional retention time space to correct retention time shifts. A progressive retention time map searching method is used to align metabolite peaks in all samples together based on optimization of the Euclidean distance and mass spectrum similarity. The effectiveness of the DISCO algorithm is demonstrated using data sets acquired under different experiment conditions and a spiked-in experiment. PMID:20476746

Wang, Bing; Fang, Aiqin; Heim, John; Bogdanov, Bogdan; Pugh, Scott; Libardoni, Mark; Zhang, Xiang

2010-06-15

415

Migration Correlation: Definition and Efficient Estimation

Abstract The aim of this paper is to explain why,cross-sectional estimated migra- tion correlations displayed,in the academic,and professional literature can be either not consistent, or inefficient, and to discuss alternative approaches. The analysis relies on a model,with stochastic migration,in which the pa- rameters of interest, that are migration correlations, are precisely defined. The impossibility of estimating consistently the migration correlations

P. Gagliardini; C. Gouriéroux

2004-01-01

416

Symmetric correlations as seen at RHIC

We analyze the forward-backward multiplicity correlation coefficient as measured by STAR. We show that in the most central Au+Au collisions bins located symmetrically around \\eta = 0 with large separation in pseudorapidity are more strongly correlated than bins located asymmetrically with smaller separation. In proton-proton collisions the opposite effect is observed. It suggests a qualitatively different behavior of the two-particle correlation as a function of pseudorapidity sum in p+p and Au+Au collisions.

Adam Bzdak

2011-08-03

417

Detrended cross-correlation analysis of electroencephalogram

NASA Astrophysics Data System (ADS)

In the paper we use detrended cross-correlation analysis (DCCA) to study the electroencephalograms of healthy young subjects and healthy old subjects. It is found that the cross-correlation between different leads of a healthy young subject is larger than that of a healthy old subject. It was shown that the cross-correlation relationship decreases with the aging process and the phenomenon can help to diagnose whether the subject's brain function is healthy or not.

Wang, Jun; Zhao, Da-Qing

2012-02-01

418

Parton and Hadron Correlations in Jets

Correlation between shower partons is first studied in high $p_T$ jets. Then in the framework of parton recombination the correlation between pions in heavy-ion collisions is investigated. Since thermal partons play very different roles in central and peripheral collisions, it is found that the correlation functions of the produced hadrons behave very differently at different centralities, especially at intermediate $p_T$. The correlation function that can best exhibit the distinctive features is suggested. There is not a great deal of overlap between what we can calculate and what has been measured. Nevertheless, some aspects of our results compare favorably with experimental data.

Rudolph C. Hwa; Zhiguang Tan

2005-03-18

419

Parallel auto-correlative statistics with VTK.

This report summarizes existing statistical engines in VTK and presents both the serial and parallel auto-correlative statistics engines. It is a sequel to [PT08, BPRT09b, PT09, BPT09, PT10] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, contingency, k-means, and order statistics engines. The ease of use of the new parallel auto-correlative statistics engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the autocorrelative statistics engine.

Pebay, Philippe Pierre [Kitware, France; Bennett, Janine Camille

2013-08-01

420

Angular correlations in Auger and fluorescence cascades

NASA Astrophysics Data System (ADS)

Angular correlations in cascades of Auger electrons and X-rays (fluorescence) are discussed. These correlations can be studied by angle-resolved coincidence measurements of two sequential emissions of Auger electrons and/or fluorescence photons. A general expression for the angular correlation function for two sequential radiation is obtained using the density matrix and statistical tensor formalism. As an example, the cascades in inner-shell atomic photoionization and photoexcitation are considered. Spectroscopic and dynamic information which can be gained from angular correlation measurement in cascade transitions is discussed. Finally, the alignment transfer and non-coincidence measurements of the angular distribution of any radiation from a cascade are discussed.

Kabachnik, Nicolai M.

1997-01-01

421

Correlated Charged Impurity Scattering in Graphene

NASA Astrophysics Data System (ADS)

We study electron transport properties of graphene in the presence of correlated charged impurities via adsorption and thermal annealing of potassium atoms. For the same density of charged scattering centers, the sample mobility sensitively depends on temperature which sets the correlation length between the scatterers. The data are well-understood by a recent theory that allows us to quantitatively extract the temperature dependence of the correlation length. Impurity correlations also offer a self-consistent explanation to the puzzling sublinear carrier-density dependence of conductivity commonly observed in monolayer graphene samples on substrates.

Yan, Jun; Fuhrer, Michael S.

2011-11-01

422

Asymmetric velocity correlations in shearing media

A model of soft frictionless disks in two dimensions at zero temperature is simulated with a shearing dynamics to study various kinds of asymmetries in sheared systems. We examine both single particle properties, the spatial velocity correlation function, and a correlation function designed to separate clockwise and counter-clockwise rotational fields from one another. Among the rich and interesting behaviors we find that the velocity correlation along the two different diagonals corresponding to compression and dilation, respectively, are almost identical and, furthermore, that a feature in one of the correlation functions is directly related to irreversible plastic events.

Peter Olsson

2010-05-11

423

Background mPing is an endogenous MITE in the rice genome, which is quiescent under normal conditions but can be induced towards mobilization under various stresses. The cellular mechanism responsible for modulating the activity of mPing remains unknown. Cytosine methylation is a major epigenetic modification in most eukaryotes, and the primary function of which is to serve as a genome defense system including taming activity of transposable elements (TEs). Given that tissue-culture is capable of inducing both methylation alteration and mPing transposition in certain rice genotypes, it provides a tractable system to investigate the possible relationship between the two phenomena. Results mPing transposition and cytosine methylation alteration were measured in callus and regenerated plants in three rice (ssp. indica) genotypes, V14, V27 and R09. All three genotypes showed transposition of mPing, though at various frequencies. Cytosine methylation alteration occurred both at the mPing-flanks and at random loci sampled globally in callus and regenerated plants of all three genotypes. However, a sharp difference in the changing patterns was noted between the mPing-flanks and random genomic loci, with a particular type of methylation modification, i.e., CNG hypermethylation, occurred predominantly at the mPing-flanks. Pearson's test on pairwise correlations indicated that mPing activity is positively correlated with specific patterns of methylation alteration at random genomic loci, while the element's immobility is positively correlated with methylation levels of the mPing's 5'-flanks. Bisulfite sequencing of two mPing-containing loci showed that whereas for the immobile locus loss of CG methylation in the 5'-flank was accompanied by an increase in CHG methylation, together with an overall increase in methylation of all three types (CG, CHG and CHH) in the mPing-body region, for the active locus erasure of CG methylation in the 5'-flank was not followed by such a change. Conclusion Our results documented that tissue culture-induced mPing activity in rice ssp. indica is correlated with alteration in cytosine methylation patterns at both random genomic loci and the elements' flanks, while the stability of mPing positively correlates with enhanced methylation levels of both the flanks and probably the elements per se. Thus, our results implicate a possible role of cytosine methylation in maintaining mPing stability under normal conditions, and in releasing the element's activity as a consequence of epigenetic perturbation in a locus-specific manner under certain stress conditions. PMID:19604382

Ngezahayo, Frederic; Xu, Chunming; Wang, Hongyan; Jiang, Lily; Pang, Jinsong; Liu, Bao

2009-01-01

424

Knowledge of local bone quality is essential for surgeons to determine operation techniques. A device for intraoperative measurement of local bone quality has been developed by the AO-Research Foundation (Densi - Probe®). We used this device to experimentally measure peak breakaway torque of trabecular bone in the proximal femur and correlated this with local bone mineral density (BMD) and failure load. Bone mineral density of 160 cadaver femurs was measured by ex situ dualenergy X-ray absorptiometry. The failure load of all femurs was analyzed by side-impact analysis. Femur fractures were fixed and mechanical peak torque was measured with the DensiProbe® device. Correlation was calculated whereas correlation coefficient and significance was calculated by Fisher’s Ztransformation. Moreover, linear regression analysis was carried out. The unpaired Student’s t-test was used to assess the significance of differences. The Ward triangle region had the lowest BMD with 0.511 g/cm2 (±0.17 g/cm2), followed by the upper neck region with 0.546 g/cm2 (±0.16 g/cm2), trochanteric region with 0.685 g/cm2 (±0.19 g/cm2) and the femoral neck with 0.813 g/cm2 (±0.2 g/cm2). Peak torque of DensiProbe® in the femoral head was 3.48 Nm (±2.34 Nm). Load to failure was 4050.2 N (±1586.7 N). The highest correlation of peak torque measured by Densi Probe® and load to failure was found in the femoral neck (r=0.64, P<0.001). The overall correlation of mechanical peak torque with T-score was r=0.60 (P<0.001). A correlation was found between mechanical peak torque, load to failure of bone and BMD in vitro. Trabecular strength of bone and bone mineral density are different aspects of bone strength, but a correlation was found between them. Mechanical peak torque as measured may contribute additional information about bone strength, especially in the perioperative testing. PMID:23888206

Grote, Stefan; Noeldeke, Tatjana; Blauth, Michael; Mutschler, Wolf; Burklein, Dominik

2013-01-01

425

Correlates of tattoos and reference groups.

520 college students from a public university in the southwest were questioned to examine correlations between having a tattoo and the presence of tattoos among their family and friends. Tattoos among both friends and family were positively correlated with respondents' having a tattoo. The magnitude of friends' influence was about double the influence of family. PMID:17305215

Roberts, Alden E; Koch, Jerome R; Armstrong, Myrna L; Owen, Donna C

2006-12-01

426

Migration correlation: Definition and efficient estimation

The aim of this paper is to explain why cross-sectional estimated migration correlations displayed in the academic and professional literature can be either not consistent, or inefficient, and to discuss alternative approaches. The analysis relies on a model with stochastic migration in which the parameters of interest, that are migration correlations, are precisely defined. The impossibility of estimating consistently the

P. Gagliardini; C. Gouriéroux

2005-01-01

427

A note on infinite extreme correlation matrices

We give a characterization for the extreme points of the convex set of correlation matrices with a countable index set. A Hermitian matrix is called a correlation matrix if it is positive semidefinite with unit diagonal entries. Using the characterization we show that there exist extreme points of any rank.

J. Kiukas; J. -P. Pellonpää

2006-12-19

428

Correlation properties of magnetosheath magnetic field fluctuations

The magnetosheath is characterized by a variety of low-frequency fluctuations, but their features and sources are different. Taking advantage of multipoint magnetic field measurements of the Cluster spacecraft, we present a statistical study to reveal properties of waves. We compute cross-correlation coefficients of magnetic field strengths as measured by pairs of the Cluster spacecraft and determine the correlation length of

O. Gutynska; J. Šafránková; Z. N?me?ek

2009-01-01

429

An extended length digital correlator threshold circuit

NASA Astrophysics Data System (ADS)

An extended length digital correlator threshold circuit for (N * M)-bit correlation using N M-bit correlators is disclosed. For the exemplary case where N=2, the digital correlator threshold circuit comprises: a first circuit for storing a preselected code word having first and second digital code portions; a first correlator responsive to the first digital code portion and an input digital data stream passing there through for periodically producing a first multibit number representative of the number of bit agreements between the bits in the digital data stream and the bits in the first digital code portion; a second correlator responsive to the second digital code portion and the digital data stream passing there through from the first correlator for periodically producing a second multibit number representative of the number of bit agreements between the bits in the digital data stream from the first correlator and the bits in the second digital code portion; and a second circuit responsive to said first and second multibit numbers for generating an output signal when the combined number of bit agreements in both of the first and second multibit numbers is at least equal to a preselected threshold number.

Leibowitz, Leon M.; Mai, T.

1992-04-01

430

ANALYZING CORRELATIONS BETWEEN STREAM AND WATERSHED ATTRIBUTES

Bivariate correlation analysis has been widely used to explore relationships between stream and watershed attributes that have all been measured on the same set of watersheds or sampling locations. Researchers routinely test H0: =0 for each correlation in a large table and then ...

431

Frequency response corrections for eddy correlation systems

Simplified expressions describing the frequency response of eddy correlation systems due to sensor response, path-length averaging, sensor separation and signal processing are presented. A routine procedure for estimating and correcting for the frequency response loss in flux and variance measurements is discussed and illustrated by application to the Institute of Hydrology's ‘Hydra’ eddy correlation system.

C. J. Moore

1986-01-01

432

Measurements of Correlation-Enhanced Collision Rates

modified by an equilibrium correlation factor g(), depending only on the correla- tion parameter e2 /a and temperature T, giving thermal ve- locity v (T/m)1/2, distance of closest approach b e2/T, and interparticle the nuclear reaction rate in dense correlated plasmas such as in giant planet interiors, brown dwarfs

California at San Diego, University of

433

Intelligence and Semen Quality Are Positively Correlated

ERIC Educational Resources Information Center

Human cognitive abilities inter-correlate to form a positive matrix, from which a large first factor, called "Spearman's g" or general intelligence, can be extracted. General intelligence itself is correlated with many important health outcomes including cardio-vascular function and longevity. However, the important evolutionary question of…

Arden, Rosalind; Gottfredson, Linda S.; Miller, Geoffrey; Pierce, Arand

2009-01-01

434

MULTIPARTICLE CORRELATIONS AT LEP1 OXANA SMIRNOVA

. To compensate for the introduced side-effects, a double-ratio is often used to measure the "true" correlation is usually interpreted as the geometrical source size, and reflects the strength of the effect. Presence (positive ), while Fermi-Dirac correlations (FDC) suppress production of fermion pairs in the region

Smirnova, Oxana

435

Strings in strongly correlated electron systems

It is shown that strongly correlated electrons on frustrated lattices like pyrochlore, checkerboard or kagome lattice can lead to the appearance of closed and open strings. They are resulting from nonlocal subsidiary conditions which propagating strongly correlated electrons require. The dynamics of the strings is discussed and a number of their properties are pointed out. Some of them are reminiscent

Peter Fulde; Frank Pollmann

2008-01-01

436

Statistical Analysis of UWB Channel Correlation Functions

Various performance metrics of impulse-radio (IR) ultrawideband (UWB) receivers are closely connected to the correlation functions of the multipath channel responses to UWB pulses. Interpulse interference is related to the autocorrelation function (ACF) of the received pulse (RP), the RP energy and its fading correspond to the ACF at zero lag, and multiple access interference is connected to the cross-correlation

Klaus Witrisal; Marco Pausini

2008-01-01

437

Tracking speckle patterns with optical correlation

It has been shown that tracking small particle motion can be accomplished by tracking the speckle pattern is produces. This paper describes various methods of real-time tracking of speckle patterns obtained from ultrasonic flow imaging of blood and tissue motion using optical correlation. Results obtained from a gray scale joint transform correlator utilizing a twisted nematic liquid crystal spatial light

Natalie Clark; Michael K. Giles; Sarah H. Harrison; Chris P. Hofer

1993-01-01

438

Correlation Image Velocimetry: A Spectral Approach

Correlation Image Velocimetry: A Spectral Approach Stephane Roux Laboratoire Surface du Verre et equation 8]. In recent years, the development of e cient tools for eld velocimetry, designed espe- cially displacement analysis. Particle Imaging Velocimetry (PIV) 10, 11], Digital Image Correlation (DIC) 2] or more

Paris-Sud XI, UniversitÃ© de

439

Own body perception based on visuomotor correlation

This work proposes a plausible approach for a humanoid robot to define its own body parts based on the correlation of two different sensory signals: vision and proprioception. The high correlation between the motions in vision and proprioception informs the robot that the visually attractive object is related to the motor function of its own body. When the robot finds

Ryo Saegusa; Giorgio Metta; Giulio Sandini

2010-01-01

440

Optical absorption in paired correlated random lattices

Optical absorption in a random one-dimensional lattice in the presence of paired correlated disorder is studied. The absorption line shape is evaluated by solving the microscopic equations of motion of the Frenkel-exciton problem in the lattice. We find that paired correlation causes the occurrence of well- defined characteristic lines in the absorption spectra which clearly differ from the case of

Francisco Dom ´ õnguez-Adame; Enrique Macia; Angel Sanchez

441

Deriving quantitative models for correlation clusters

Correlation clustering aims at grouping the data set into correlation clusters such that the objects in the same cluster exhibit a certain density and are all associated to a common arbitrarily oriented hyperplane of arbitrary dimensionality. Several algorithms for this task have been proposed recently. However, all algorithms only compute the partitioning of the data into clusters. This is only

Elke Achtert; Christian Böhm; Hans-peter Kriegel; Peer Kröger; Arthur Zimek

2006-01-01

442

THE EFFECT OF CORRELATED ARRIVALS ON QUEUES

Using Markov renewal arrival processes, a study of the effect of serial correlations in the arrival process on the mean queueing performance has been done. We show that positive serial correlations may have major impact on the mean queue lengths (and consequently on other performance measures).

B. EDDY PATUWO; RALPH L. DISNEY; DONALD C. McNICKLE

1993-01-01

443

Morphological signatures and genomic correlates in glioblastoma

Large multimodal datasets such as The Cancer Genome Atlas present an opportunity to perform correlative studies of tissue morphology and genomics to explore the morphological phenotypes associated with gene expression and genetic alterations. In this paper we present an investigation of Cancer Genome Atlas data that correlates morphology with recently discovered molecular subtypes of glioblastoma. Using image analysis to segment

Lee A. D. Cooper; Jun Kong; Fusheng Wang; Tahsin Kurc; Carlos S. Moreno; Daniel J. Brat; Joel H. Saltz

2011-01-01

444

Using unsupervised learning for Network Alert Correlation

Using unsupervised learning for Network Alert Correlation Reuben Smith1 , Nathalie Japkowicz1 of Ottawa ON Canada 2 Defence Research and Development Canada (DRDC) Ottawa ON Canada Abstract. Alert correlation systems are post-processing modules that enable intrusion analysts to find important alerts

Japkowicz, Nathalie

445

ALERT CORRELATION FOR EXTRACTING ATTACK STRATEGIES

ALERT CORRELATION FOR EXTRACTING ATTACK STRATEGIES Bin Zhu and Ali A. Ghorbani Faculty of Computer Science University of New Brunswick Fredericton, New Brunswick, Canada Abstract Alert correlation is an important technique for managing large the volume of intrusion alerts that are raised by heterogenous

Ghorbani, Ali

446

Epidemic spreading in correlated complex networks

We study a dynamical model of epidemic spreading on complex networks in which there are explicit correlations among the node's connectivities. For the case of Markovian complex networks, showing only correlations between pairs of nodes, we find an epidemic threshold inversely proportional to the largest eigenvalue of the connectivity matrix that gives the average number of links, which from a

Marián Boguñá; Romualdo Pastor-Satorras

2002-01-01

447

Online Movement Correlation of Wireless Sensor Nodes

Sensor nodes can autonomously form ad-hoc groups based on their common context. We propose a solution for grouping sensor nodes attached on the same vehicles on wheels. The nodes periodically receive the movement data from their neighbours and calculate the correlation coefficients over a time history. A high correlation coefficient implies that the nodes are moving together. We demonstrate the

Mihai Marin-Perianu; Raluca Marin-Perianu; Paul Havinga; J. Scholten

2007-01-01

448

Single Molecule Measurements Using Correlation Force Spectroscopy

NASA Astrophysics Data System (ADS)

Thermal noise represents a fundamental limit in force measurements. We describe single molecule measurements using two AFM cantilevers that have lower thermal noise than single-cantilever measurements. We achieve this by measuring the correlated thermal motions of two closely spaced cantilevers. Because only correlated thermal noise is measured, there is lower noise. In addition, the use of two cantilevers produces both decreased hydrodynamic fluid damping and decreased van der Waals forces acting on an AFM probe, both of which are interferences in single molecule measurements. Analysis of the correlated motions reveals molecular damping, a parameter that is not sensed with conventional (pulling) AFM single molecule force spectroscopy. When a molecule is straddled between the two cantilevers, the correlation arises from the solvent coupling as well as stiffness and damping of the molecule. We will describe the technique of correlation force spectroscopy and measurements of the mechanical properties of single polymer chains such as dextran.

Radiom, Milad; Robbins, Brian; Walz, John; Paul, Mark; Ducker, William

2013-03-01

449

Short-Range Nucleon-Nucleon Correlations

Valence-shell nucleon knock-out experiments, such as 12C(e,e'p)11B, measure less strength then is predicted by independent particle shell model calculations. The theoretical solution to this problem is to include the correlations between the nucleons in the nucleus in the calculations. Motivated by these results, many electron scattering experiments have tried to directly observe these correlations in order to gain new insight into the short-range part of the nucleon-nucleon potential. Unfortunately, many competing mechanisms can cause the same observable final-state as an initial-state correlation, making truly isolating the signal extremely challenging. This paper reviews the recent experimental evidence for short-range correlations, as well as explores the possibility that such correlations are responsible for the EMC effect in the 0.3 < xB < 0.7 deep inelastic scattering ratios.

Douglas W. Higinbotham

2010-10-21

450

Short-Range Nucleon-Nucleon Correlations

Valence-shell nucleon knock-out experiments, such as 12C(e,e'p)11B, measure less strength then is predicted by independent particle shell model calculations. The theoretical solution to this problem is to include the correlations between the nucleons in the nucleus in the calculations. Motivated by these results, many electron scattering experiments have tried to directly observe these correlations in order to gain new insight into the short-range part of the nucleon-nucleon potential. Unfortunately, many competing mechanisms can cause the same observable final-state as an initial-state correlation, making truly isolating the signal extremely challenging. This paper reviews the recent experimental evidence for short-range correlations, as well as explores the possibility that such correlations are responsible for the EMC effect in the 0.3 < xB < 0.7 deep inelastic scattering ratios.

Douglas Higinbotham

2011-10-01

451

Correlates of Protection Induced by Vaccination?

This paper attempts to summarize current knowledge about immune responses to vaccines that correlate with protection. Although the immune system is redundant, almost all current vaccines work through antibodies in serum or on mucosa that block infection or bacteremia/viremia and thus provide a correlate of protection. The functional characteristics of antibodies, as well as quantity, are important. Antibody may be highly correlated with protection or synergistic with other functions. Immune memory is a critical correlate: effector memory for short-incubation diseases and central memory for long-incubation diseases. Cellular immunity acts to kill or suppress intracellular pathogens and may also synergize with antibody. For some vaccines, we have no true correlates, but only useful surrogates, for an unknown protective response. PMID:20463105

Plotkin, Stanley A.

2010-01-01

452

Graph-Theoretic Approach to Quantum Correlations

Correlations in Bell and noncontextuality inequalities can be expressed as a positive linear combination of probabilities of events. Exclusive events can be represented as adjacent vertices of a graph, so correlations can be associated to a subgraph. We show that the maximum value of the correlations for classical, quantum, and more general theories is the independence number, the Lov\\'asz number, and the fractional packing number of this subgraph, respectively. We also show that, for any graph, there is always a correlation experiment such that the set of quantum probabilities is exactly the Gr\\"otschel-Lov\\'asz-Schrijver theta body. This identifies these combinatorial notions as fundamental physical objects and provides a method for singling out experiments with quantum correlations on demand.

Adan Cabello; Simone Severini; Andreas Winter

2014-01-28

453

Spectral correlations of fractional Brownian motion

Fractional Brownian motion (fBm) is a ubiquitous nonstationary model for many physical processes with power-law time-averaged spectra. In this paper, we exploit the nonstationarity to derive the full spectral correlation structure of fBm. Starting from the time-varying correlation function, we derive two different time-frequency spectral correlation functions (the ambiguity function and the Kirkwood-Rihaczek spectrum), and one dual-frequency spectral correlation function. The dual-frequency spectral correlation has a surprisingly simple structure, with spectral support on three discrete lines. The theoretical predictions are verified by spectrum estimates of Monte Carlo simulations and of a time series of earthquakes with a magnitude of 7 and higher.

Oigaard, Tor Arne; Hanssen, Alfred [Department of Physics and Technology, University of Tromsoe, NO-9037 Tromsoe (Norway); Scharf, Louis L. [Department of Electrical and Computer Engineering and Department of Statistics, Colorado State University, Fort Collins, Colorado 80523 (United States)

2006-09-15

454

Method for High Accuracy Multiplicity Correlation Measurements

Multiplicity correlation measurements provide insight into the dynamics of high energy collisions. Models describing these collisions need these correlation measurements to tune the strengths of the underlying QCD processes which influence all observables. Detectors, however, often possess limited coverage or reduced efficiency that influence correlation measurements in obscure ways. In this paper, the effects of non-uniform detection acceptance and efficiency on the measurement of multiplicity correlations between two distinct detector regions (termed forward-backward correlations) are derived. This result is transformed into a correction method. Verification of the presented correction method is provided through simulations using different event generators. The result of the method allows one to correct measurements in a simulation independent manner with high accuracy and thereby shed light on the underlying processes.

K. Gulbrandsen; C. Soegaard

2014-08-14

455

Method for High Accuracy Multiplicity Correlation Measurements

Multiplicity correlation measurements provide insight into the dynamics of high energy collisions. Models describing these collisions need these correlation measurements to tune the strengths of the underlying QCD processes which influence all observables. Detectors, however, often possess limited coverage or reduced efficiency that influence correlation measurements in obscure ways. In this paper, the effects of non-uniform detection acceptance and efficiency on the measurement of multiplicity correlations between two distinct detector regions (termed forward-backward correlations) are derived. This result is transformed into a correction method. Verification of the presented correction method is provided through simulations using different event generators. The result of the method allows one to correct measurements in a simulation independent manner with high accuracy and thereby shed light on the underlying processes.

Gulbrandsen, K

2014-01-01

456

Communication: A non-empirical correlation factor model for the exchange-correlation energy

NASA Astrophysics Data System (ADS)

A persistent challenge in density functional theory is the construction of a nonempirical correlation functional that is compatible with the exact exchange energy. To solve this problem, we develop a correlation factor approach in which an exchange hole model, yielding the exact exchange energy, is multiplied by a correlation factor that turns the exchange hole into an exchange-correlation hole. This results in an accurate correlation energy functional that is determined solely through physical constraints. Subject to the properties of the employed