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Last update: August 15, 2014.

1

Pearson's Correlation Coefficient

NSDL National Science Digital Library

This tutorial on Pearson's Correlation Coefficient includes the definition, assumptions, and characteristics of r as well as related statistics and hypothesis test procedures. One section instructs users to find correlation in the WINKS software, but those without the software can still use the tutorial. An exercise is given at the end that can be done with any statistical software package.

2009-01-09

2

Pearson's Product-Moment Coefficient of Correlation

NSDL National Science Digital Library

This tutorial, created by Thomas W. MacFarland of Nova Southeastern University, explains the theory and use of Pearson's Product Moment Coefficient of Correlation and demonstrates it with an example on GPA and test scores. Data sets are provided in both SPSS and Minitab code. This is a great resource for anyone looking for a more in-depth study of statistics. This could be used as either a teaching guide for educators or simply further practice for students.

Macfarland, Thomas W.

2009-09-11

3

Sample Size Requirements for Estimating Pearson, Spearman and Kendall Correlations.

ERIC Educational Resources Information Center

Reviews interval estimates of the Pearson, Kendall tau-alpha, and Spearman correlates and proposes an improved standard error for the Spearman correlation. Examines the sample size required to yield a confidence interval having the desired width. Findings show accurate results from a two-stage approximation to the sample size. (SLD)

Bonett, Douglas G.; Wright, Thomas A.

2000-01-01

4

Approximating Pearson Product-Moment Correlations from Kendall's Tau and Spearman's Rho.

ERIC Educational Resources Information Center

The use of Monte Carlo methods demonstrated that a formula presented by M. G. Kendall for estimating Pearson's rho from tau is somewhat more accurate than a formula presented by K. Pearson for estimating Pearson's rho from a Spearman's rho coefficient. Implications for meta-analysis of correlations are discussed. (SLD)

Rupinski, Melvin T.; Dunlap, William P.

1996-01-01

5

Non-Simulation Based Method for Inducing Pearson's Correlation Between Input Random Variables.

National Technical Information Service (NTIS)

Several previously published papers have cited the need to include correlation in risk analysis models. In particular, a landmark paper published by Philip Lurie and Matthew Goldberg presented a methodology for inducing Pearson's correlation between input...

E. R. Druker P. J. Braxton R. L. Coleman

2008-01-01

6

Robustness of Two Formulas to Correct Pearson Correlation for Restriction of Range

ERIC Educational Resources Information Center

Many research studies involving Pearson correlations are conducted in settings where one of the two variables has a restricted range in the sample. For example, this situation occurs when tests are used for selecting candidates for employment or university admission. Often after selection, there is interest in correlating the selection variable,…

tran, minh

2011-01-01

7

ERIC Educational Resources Information Center

Criticizes the use of Pearson's correlation coefficient in author cocitation analysis (ACA), a technique used to analyze the intellectual structure of a given scientific field, and sets forth two natural requirements that a similarity measure applied in ACA should satisfy. Uses real and hypothetical data to obtain counterexamples to both…

Ahlgren, Per; Jarneving, Bo; Rousseau, Ronald

2003-01-01

8

Autofocus algorithm using one-dimensional Fourier transform and Pearson correlation

NASA Astrophysics Data System (ADS)

A new autofocus algorithm based on one-dimensional Fourier transform and Pearson correlation for Z automatized microscope is proposed. Our goal is to determine in fast response time and accuracy, the best focused plane through an algorithm. We capture in bright and dark field several images set at different Z distances from biological organism sample. The algorithm uses the one-dimensional Fourier transform to obtain the image frequency content of a vectors pattern previously defined comparing the Pearson correlation of these frequency vectors versus the reference image frequency vector, the most out of focus image, we find the best focusing. Experimental results showed the algorithm has fast response time and accuracy in getting the best focus plane from captured images. In conclusions, the algorithm can be implemented in real time systems due fast response time, accuracy and robustness. The algorithm can be used to get focused images in bright and dark field and it can be extended to include fusion techniques to construct multifocus final images beyond of this paper.

Bueno Mario, A.; Alvarez-Borrego, Josue; Acho, L.

2004-10-01

9

Erhardt and Czado (2008) suggest an approximative method for sampling high- dimensional count random variables with a specified Pearson correlation. They utilize Gaussian copulas for the construction of multivariate discrete distributions. A major task is to determine the appropriate copula parameters for the achievement of a spec- ified target correlation. Erhardt and Czado (2008) develop an optimization routine to determine

Vinzenz Erhardt; Claudia Czado

10

ERIC Educational Resources Information Center

In order to circumvent the influence of correlation in paired-samples and repeated measures experimental designs, researchers typically perform a one-sample Student "t" test on difference scores. That procedure entails some loss of power, because it employs N - 1 degrees of freedom instead of the 2N - 2 degrees of freedom of the…

Zimmerman, Donald W.

2012-01-01

11

Pearson diffusions are governed by diffusion equations with polynomial coefficients. Fractional Pearson diffusions are governed by the corresponding time-fractional diffusion equation. They are useful for modeling sub-diffusive phenomena, caused by particle sticking and trapping. This paper provides explicit strong solutions for fractional Pearson diffusions, using spectral methods. It also presents stochastic solutions, using a non-Markovian inverse stable time change.

Leonenko, Nikolai N.; Meerschaert, Mark M.

2013-01-01

12

NASA Astrophysics Data System (ADS)

Gene coexpression analysis is a powerful approach to elucidate gene function. We have established and developed this approach using vast amount of publicly available gene expression data measured by microarray techniques. The coexpressed genes are used to estimate gene function of the guide gene or to construct gene coexpression networks. In the case to construct gene networks, researchers should introduce an arbitrary threshold of gene coexpression, because gene coexpression value is continuous value. In the viewpoint to introduce common threshold of gene coexpression, we previously reported rank of Pearson's correlation coefficient (PCC) is more useful than the original PCC value. In this manuscript, we re-assessed the measure of gene coexpression to construct gene coexpression network, and found that mutual rank (MR) of PCC showed better performance than rank of PCC and the original PCC in low false positive rate.

Obayashi, Takeshi; Kinoshita, Kengo

2013-01-01

13

National Technical Information Service (NTIS)

This report discusses the use of Pearson curves to give approximate percentage points to intractable distributions, when the first four moments (or three moments and one end-point) are available. It is shown how to fit the curves, and their effectiveness ...

H. Solomon M. A. Stephens

1975-01-01

14

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

15

Pearson's Functions to Describe FSW Weld Geometry

NASA Astrophysics Data System (ADS)

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

2011-01-01

16

Karl Pearson in Russian Contexts

The confluence of statistics and probability into mathematical statistics in the Russian Empire through the interaction, 1910-1917, of A.A. Chuprov and A.A. Markov was influenced by the writings of the English Biometric School, especially those of Karl Pearson. The appearance of the Russian-language exposition of Pearsonian ideas by E. E. Slutsky in 1912 was instrumental in this confluence. Slutsky's predecessors

Eugene Seneta

2009-01-01

17

NSDL National Science Digital Library

This chapter will discuss the concept of correlation , which is used in later chapters that will explain the concepts of validity and reliability. Here, the authors introduce the Pearson correlation coefficient, a statistic that is used with ratio

Christmann, Edwin P.; Badgett, John L.

2008-11-01

18

Corneal endothelial dysfunction in Pearson syndrome.

Mitochondrial disorders are associated with well recognized ocular manifestations. Pearson syndrome is an often fatal, multisystem, mitochondrial disorder that causes variable bone marrow, hepatic, renal and pancreatic exocrine dysfunction. Phenotypic progression of ocular disease in a 12-year-old male with Pearson syndrome is described. This case illustrates phenotypic drift from Pearson syndrome to Kearns-Sayre syndrome given the patient's longevity. Persistent corneal endothelial failure was noted in addition to ptosis, chronic external ophthalmoplegia and mid-peripheral pigmentary retinopathy. We propose that corneal edema resulting from corneal endothelial metabolic pump failure occurs within a spectrum of mitochondrial disorders. PMID:21936618

Kasbekar, Shivani A; Gonzalez-Martin, Jose A; Shafiq, Ayad E; Chandna, Arvind; Willoughby, Colin E

2013-01-01

19

Approximation of Pearson Type IV Tail Probabilities.

National Technical Information Service (NTIS)

Simple approximating functions for tail probabilities of the Pearson Type IV distribution are obtained by using the B sub n transformations and by truncating the continued fraction expansion. The behavior of these approximations is then investigated for v...

W. A. Woodward

1975-01-01

20

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

21

NSDL National Science Digital Library

This tutorial on the "One Sample t-Test" includes its definition, assumptions, hypotheses, and results. An example using output from the WINKS software is given, but those without the software can still use the tutorial. An exercise is given at the end that can be done with any statistical software package.

2009-01-09

22

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

23

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.

24

Parental Socio-Economic Status as Correlate of Child Labour in Ile-Ife, Nigeria

ERIC Educational Resources Information Center

This study investigated the relationship between parental socio-economic status and child labour practices in Ile-Ife, Nigeria. The study employed survey method to gather data from 200 parents which constituted the study population. Pearson Product Moment Correlation and t-test statistics were used for the data analyses. The outcome of the study…

Elegbeleye, O. S.; Olasupo, M. O.

2012-01-01

25

23. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

23. Historic American Buildings Survey E. R. Pearson, Photographer 1969 STAIRS AND HALL, SECOND FLOOR, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

26

18. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

18. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

27

1. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

1. Historic American Buildings Survey E. R. Pearson, Photographer 1969 PRESERVATORY ON LEFT, WASHHOUSE ON RIGHT - Shaker Centre Family Preservatory, West side of U.S. Route 68, South Union, Logan County, KY

28

41. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

41. Historic American Buildings Survey E. R. Pearson, Photographer 1969 THIRD FLOOR AND ATTIC FLOOR PLAN - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

29

27. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

27. Historic American Buildings Survey E. R. Pearson, Photographer 1972 STAIR RAIL, FIRST ATTIC, LOOKING SOUTHEAST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

30

34. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

34. Historic American Buildings Survey E. R. Pearson, Photographer 1972 KITCHEN WALL, LOOKING SOUTHWEST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

31

22. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

22. Historic American Buildings Survey E. R. Pearson, Photographer 1969 MEETING ROOM, FIRST FLOOR, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

32

32. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

32. Historic American Buildings Survey E. R. Pearson, Photographer 1972 REAR STAIRWAY, NORTH END, LOOKING NORTHEAST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

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21. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

21. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING EAST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

34

20. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

20. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

35

35. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

35. Historic American Buildings Survey E. R. Pearson, Photographer 1972 BAKEROOM, BASEMENT LEVEL, LOOKING WEST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

36

13. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

13. Historic American Buildings Survey E. R. Pearson, Photographer 1972 CORNER DETAIL, EAST SIDE, LOOKING SOUTH, MINISTRY'S SHOP IN BACKGROUND - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

37

2. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

2. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ENTRANCE STAIRS, LOOKING SOUTHWEST - Shaker Centre Family Ministry's Shop & Dwelling, East side of U.S. Route 68, South Union, Logan County, KY

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17. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

17. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

39

14. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

14. Historic American Buildings Survey E. R. Pearson, Photographer 1972 IRON RAILING, EAST SIDE, LOOKING SOUTHWEST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

40

30. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

30. Historic American Buildings Survey E. R. Pearson, Photographer 1972 EAST ROOM, FIRST ATTIC, LOOKING EAST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

41

10. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

10. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ROOF DETAIL AND STONE GUTTER, EAST SIDE, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

42

12. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

12. Historic American Buildings Survey E. R. Pearson, Photographer 1969 SOUTHEAST CORNER DETAIL, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

43

29. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

29. Historic American Buildings Survey E. R. Pearson, Photographer 1972 HALL, FIRST ATTIC, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

44

15. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

15. Historic American Buildings Survey E. R. Pearson, Photographer 1972 FOOT SCRAPER, EAST SIDE, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

45

16. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

16. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING SOUTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

46

5. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

5. Historic American Buildings Survey E. R. Pearson, Photographer 1972 CORNER DETAIL, EAST SIDE, LOOKING SOUTH, MINISTRY'S SHOP IN BACKGROUND - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

47

1. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

1. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT ELEVATION, LOOKING SOUTH - Shaker Centre Family Ministry's Shop & Dwelling, East side of U.S. Route 68, South Union, Logan County, KY

48

19. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

19. Historic American Buildings Survey E. R. Pearson, Photographer 1969 FRONT HALL, FIRST FLOOR, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

49

3. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

3. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ENTRANCE STAIRS, LOOKING WEST - Shaker Centre Family Ministry's Shop & Dwelling, East side of U.S. Route 68, South Union, Logan County, KY

50

11. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

11. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ROOF DETAIL AND STONE GUTTER, EAST SIDE, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

51

4. Historic American Buildings Survey E. R. Pearson, Photographer 1969 ...

4. Historic American Buildings Survey E. R. Pearson, Photographer 1969 STONE WALK IN FRONT OF BUILDING - Shaker Centre Family Ministry's Shop & Dwelling, East side of U.S. Route 68, South Union, Logan County, KY

52

24. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

24. Historic American Buildings Survey E. R. Pearson, Photographer 1972 FRONT HALL, SECOND FLOOR, LOOKING NORTH - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

53

26. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

26. Historic American Buildings Survey E. R. Pearson, Photographer 1972 STAIRS IN FIRST ATTIC HALL TO SECOND ATTIC, LOOKING SOUTHWEST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

54

40. Historic American Buildings Survey E. R. Pearson, Photographer January ...

40. Historic American Buildings Survey E. R. Pearson, Photographer January 1970 THIRD FLOOR AND ATTIC FLOOR PLAN - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

55

31. Historic American Buildings Survey E. R. Pearson, Photographer 1972 ...

31. Historic American Buildings Survey E. R. Pearson, Photographer 1972 CLOTHES ROOM, FIRST ATTIC, SOUTHEAST CORNER, LOOKING EAST - Shaker Centre Family Dwelling House, West side of U.S. Route 68, South Union, Logan County, KY

56

Genetics Home Reference: Pearson marrow-pancreas syndrome

Pearson marrow-pancreas syndrome Mitochondrial DNA Related Condition(s) References Quick links to this topic MedlinePlus Health information Additional NIH Resources National Institutes of Health Educational resources Information ...

57

3. Historic American Buildings Survey, Elmer R. Pearson, Photographer, 1968 ...

3. Historic American Buildings Survey, Elmer R. Pearson, Photographer, 1968 ELEVATION, LOOKING NORTHWEST. - Shaker Centre Family, Broom Shop, East side of Oxford Road, White Water Park, Hamilton County, OH

58

An Interview with Mike Pearson of Brith Gof

In December 1992 Geraldine Cousin talked to Mike Pearson, a founder member of Brith Gof, the Welsh theatre company that has pioneered epic, site?specific work in Britain and Europe. In addition to large?scale, site?specific projects, Mike Pearson discusses in Patagonia, a theatre piece based on life in the Welsh community in Patagonia, and two small?scale ventures: a one?man show, From

Geraldine Cousin

1994-01-01

59

Minimax Tests and the Neyman-Pearson Lemma for Capacities

Robust test problems between two approximately known simple hypotheses can be formalized as minimax test problems between two composite hypotheses. We show that if the composite hypotheses can be described in terms of alternating capacities of order 2 (in the sense of Choquet), then the minimax tests are ordinary Neyman-Pearson tests between a fixed representative pair of simple hypotheses; moreover,

Peter J. Huber; Volker Strassen

1973-01-01

60

Spatial trends in Pearson Type III statistical parameters

Spatial trends in the statistical parameters (mean, standard deviation, and skewness coefficient) of a Pearson Type III distribution of the logarithms of annual flood peaks for small rural basins (less than 90 km2) are delineated using a climate factor CT, (T=2-, 25-, and 100-yr recurrence intervals), which quantifies the effects of long-term climatic data (rainfall and pan evaporation) on observed T-yr floods. Maps showing trends in average parameter values demonstrate the geographically varying influence of climate on the magnitude of Pearson Type III statistical parameters. The spatial trends in variability of the parameter values characterize the sensitivity of statistical parameters to the interaction of basin-runoff characteristics (hydrology) and climate. -from Authors

Lichty, R. W.; Karlinger, M. R.

1995-01-01

61

Decentralized fuzzy CFAR detectors in homogeneous Pearson clutter background

In this paper, we analyze the decentralized CA-CFAR, GO-CFAR and SO-CFAR detectors using fuzzy fusion rules in heavy tailed homogeneous clutter modeled by a Pearson distribution. We generalize our study by considering a distributed detection system with ‘L’ detectors and using the ‘maximum’, ‘minimum’, ‘algebraic sum’ and ‘algebraic product’ fuzzy rules at the data fusion center. For each detector considered,

Hilal A. Meziani; Faouzi Soltani

2011-01-01

62

A New Family of Solvable Pearson-Dirichlet Random Walks

An n-step Pearson-Gamma random walk in R d starts at the origin and consists of n independent steps with gamma distributed lengths and uniform orientations. The gamma distribution of each step length has a shape parameter q>0. Constrained random walks of n steps in R d are obtained from the latter walks by imposing that the sum of the step

Gérard Le Caër

2011-01-01

63

A New Family of Solvable Pearson-Dirichlet Random Walks

An n-step Pearson-Gamma random walk in ?\\u000a d\\u000a starts at the origin and consists of n independent steps with gamma distributed lengths and uniform orientations. The gamma distribution of each step length has\\u000a a shape parameter q>0. Constrained random walks of n steps in ?\\u000a d\\u000a are obtained from the latter walks by imposing that the sum of the step

Gérard Le Caër

2011-01-01

64

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

65

Sample Size for Correlation Estimates.

National Technical Information Service (NTIS)

This thesis examines the classical measure of correlation (Pearson's R) and two nonparametric measures of correlation (Spearman's r and Kendall's tau) with the goal of determining the number of samples needed to estimate a correlation coefficient with a 9...

K. Salar

1989-01-01

66

Neyman Pearson detection of K-distributed random variables

NASA Astrophysics Data System (ADS)

In this paper a new detection method for sonar imagery is developed in K-distributed background clutter. The equation for the log-likelihood is derived and compared to the corresponding counterparts derived for the Gaussian and Rayleigh assumptions. Test results of the proposed method on a data set of synthetic underwater sonar images is also presented. This database contains images with targets of different shapes inserted into backgrounds generated using a correlated K-distributed model. Results illustrating the effectiveness of the K-distributed detector are presented in terms of probability of detection, false alarm, and correct classification rates for various bottom clutter scenarios.

Tucker, J. Derek; Azimi-Sadjadi, Mahmood R.

2010-04-01

67

Mitochondrial DNA deletion in a patient with combined features of Leigh and Pearson syndromes

We describe a heteroplasmic 4237 bp mitochondrial DNA (mtDNA) deletion in an 11 year old girl who has suffered from progressive illness since birth. She has some features of Leigh syndrome (global developmental delay with regression, brainstem dysfunction and lactic acidosis), together with other features suggestive of Pearson syndrome (history of pancytopenia and failure to thrive). The deletion was present at a level greater than 50% in skeletal muscle, but barely detectable in skin fibroblasts following Southern blot analysis, and only observed in blood following PCR analysis. The deletion spanned nt 9498 to nt 13734, and was flanked by a 12 bp direct repeat. Genes for cytochrome c oxidase subunit III, NADH dehydrogenase subunits 3, 4L, 4 and 5, and tRNAs for glycine, arginine, histidine, serine({sup AGY}) and leucine({sup CUN}) were deleted. Southern blotting also revealed an altered Apa I restriction site which was shown by sequence analysis to be caused by G{r_arrow}A nucleotide substitution at nt 1462 in the 12S rRNA gene. This was presumed to be a polymorphism. No abnormalities of mitochondrial ultrastructure, distribution or of respiratory chain enzyme complexes I-IV in skeletal muscle were observed. Mitochondrial disorders with clinical features overlapping more than one syndrome have been reported previously. This case further demonstrates the difficulty in correlating observed clinical features with a specific mitochondrial DNA mutation.

Blok, R.B.; Thorburn, D.R.; Danks, D.M. [Royal Children`s Hospital, Melbourne (Australia)] [and others

1994-09-01

68

Modification of Visual Approach Slope Indicator Baffles at Pearson Field Airpark, Vancouver, WA.

National Technical Information Service (NTIS)

This technical note describes a research effort that was accomplished to correct a safety deficiency with a Visual Approach Slope Indicator (VASI) system at the Pearson Field Airpark in Vancouver, Washington. During a recent inspection flight, the VASI sy...

J. W. Patterson

2007-01-01

69

Generalised decentralised fuzzy CA-CFAR detector in Pearson distributed clutter

In this paper, we analyze the decentralized CA-CFAR detector using fuzzy fusion rules in heavy tailed clutter modeled by a Pearson distribution. We generalize our study by considering a distributed detection system with \\

Hilal Abdenour Meziani; Faouzi Soltani

2010-01-01

70

Machining introduces residual stresses at the specimen surface and modifies the microstructure and the texture in a small volume close to the surface. Such changes are important in controlling the corrosion behaviour of machined workpieces in the presence of an aggressive environment. In the present paper, the relationships between cutting parameters and the surface and subsurface characteristics of machined copper

J. Gravier; V. Vignal; S. Bissey-Breton; J. Farre

2008-01-01

71

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

2014-03-01

72

Optimum second threshold for the CFAR binary integrator in Pearson-distributed clutter

In this paper, we propose to analyze the binary integration of the cell-averaging constant false-alarm rate (CA-CFAR) and\\u000a order statistics constant false-alarm rate (OS-CFAR) detectors in the presence of non-Gaussian spiky clutter modeled as a\\u000a Pearson distribution. We derive new closed form expressions for false alarm and detection probabilities for the CA-CFAR detector\\u000a in the presence of Pearson-distributed clutter backgrounds.

Hilal A. Meziani; Faouzi Soltani

73

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. PMID:24249044

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

2014-02-01

74

The PDF and CF of Pearson type IV distributions and the ML estimation of the parameters

Recently, in the area of finance, especially for the risk management, some heavy-tailed and skewed distributions are strongly required. The Pearson type IV distribution can represent various kurtosis and skewness. However, it has not been used for practical purpose because of the difficulties of its implementation. This paper discusses the practical methods which could overcome various difficulties involved. Type IV

Yuichi Nagahara

1999-01-01

75

The Fitting of Pearson Curves to Sums of Independent Random Variables.

National Technical Information Service (NTIS)

It is shown that the distribution of a sum of independent beta random variables is often well approximated by a properly scaled beta distribution. The relationship between the type of Pearson curve which best fits a sum of independent random variables and...

T. Sellke

1983-01-01

76

A New Way to Teach (or Compute) Pearson's "r" without Reliance on Cross-Products

ERIC Educational Resources Information Center

Many students have difficulty seeing the conceptual link between bivariate data displayed in a scatterplot and the statistical summary of the relationship, "r." This article shows how to teach (and compute) "r" such that each datum's direct and indirect influences are made apparent and used in a new formula for calculating Pearson's "r."

Huck, Schuyler W.; Ren, Bixiang; Yang, Hongwei

2007-01-01

77

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

78

Performance Analysis of Distributed Fuzzy CA-CFAR Detector in Pearson Distributed Clutter

In order to improve the radar's detection performance under Pearson distributed background clutter, the problem of designing CA-CFAR detector based on fuzzy logic is studied in this paper. A kind of distributed fuzzy CA-CFAR detection scheme including two detectors is proposed here. Two detectors compute the values of the membership function to the false alarm space from the samples of

Long Cai; Xiaochuan Ma; Chengpeng Hao; Xiaoguang Yang

2009-01-01

79

mtDNA Deletion in an Iranian Infant with Pearson Marrow Syndrome

Background Pearson syndrome (PS) is a rare multisystem mitochondrial disorder of hematopoietic system, characterized by refractory sideroblastic anemia, pancytopenia, exocrine pancreatic insufficiency, and variable neurologic, hepatic, renal, and endocrine failure. Case Presentation We describe a six-month-old female infant with Pearson marrow syndrome who presented with neurological manifestations. She had several episodes of seizures. Hematopoietic abnormalities were macrocytic anemia and neutropenia. Bone marrow aspiration revealed a cellular marrow with marked vacuolization of erythroid and myeloid precursors. Analysis of mtDNA in peripheral blood showed 8.5 kb deletion that was compatible with the diagnosis of PS. Conclusion PS should be considered in infants with neurologic diseases, in patients with cytopenias, and also in patients with acidosis or refractory anemia.

Arzanian, Mohammad Taghi; Eghbali, Aziz; Karimzade, Parvaneh; Ahmadi, Mitra; Houshmand, Massoud; Rezaei, Nima

2010-01-01

80

Is the Pearson r[squared] Biased, and if So, What Is the Best Correction Formula?

ERIC Educational Resources Information Center

In this study the authors investigated the use of 5 (i.e., Claudy, Ezekiel, Olkin-Pratt, Pratt, and Smith) R[squared] correction formulas with the Pearson r[squared]. The authors estimated adjustment bias and precision under 6 x 3 x 6 conditions (i.e., population [rho] values of 0.0, 0.1, 0.3, 0.5, 0.7, and 0.9; population shapes normal, skewness…

Wang, Zhongmiao; Thompson, Bruce

2007-01-01

81

Choosing the Best Correction Formula for the Pearson r[superscript 2] Effect Size

ERIC Educational Resources Information Center

In the present Monte Carlo simulation study, the authors compared bias and precision of 7 sampling error corrections to the Pearson r[superscript 2] under 6 x 3 x 6 conditions (i.e., population ? values of 0.0, 0.1, 0.3, 0.5, 0.7, and 0.9, respectively; population shapes normal, skewness = kurtosis = 1, and skewness = -1.5 with kurtosis = 3.5;…

Skidmore, Susan Troncoso; Thompson, Bruce

2011-01-01

82

MONICA-a real-time algorithm for the optimum coherent Neyman-Pearson radar receiver

This paper introduces a new signal processing algorithm which enables the optimum coherent Neyman-Pearson radar receiver presented by Lovli (see International Radar Conference, Washington DC, USA, 1995), SOLVEIG1, to be implemented in real-time. As the required processing power increases exponentially with the number of pulses to be integrated, the basic SOLVEIG1 may only be utilised for a very low number

L. Nesse

1996-01-01

83

The aims of this study were to evaluate the reliability of a modified agility T-test (MAT) and to examine its relationship to the free countermovement jump (FCMJ) and the 10-m straight sprint (10mSS). In this new version, we preserved the same nature of displacement of the T-test but we reduced the total distance to cover. A total of 86 subjects (34 women: age = 22.6 +/- 1.4 years; weight = 63.7 +/- 10.2 kg; height = 1.65 +/- 0.05 m; body mass index = 23.3 +/- 3.3 kg x m(-2) and 52 men: age = 22.4 +/- 1.5 years; weight = 68.7 +/- 8.0 kg; height = 1.77 +/- 0.06 m; body mass index = 22.0 +/- 2.0 kg x m(-2)) performed MAT, T-test, FCMJ, and 10mSS. Our results showed no difference between test-retest MAT scores. Intraclass reliability of the MAT was greater than 0.90 across the trials (0.92 and 0.95 for women and men, respectively). The mean difference (bias) +/- the 95% limits of agreement was 0.03 +/- 0.37 seconds for women and 0.03 +/- 0.33 seconds for men. MAT was correlated to the T-test (r = 0.79, p < 0.001 and r = 0.75, p < 0.001 for women and men, respectively). Significant correlations were found between both MAT and FCMJ, and MAT and 10mSS for women (r = -0.47, p < 0.01 and r = 0.34, p < 0.05, respectively). No significant correlations were found between MAT and all other tests for men. These results indicate that MAT is a reliable test to assess agility. The weak relationship between MAT and strength and straight speed suggests that agility requires other determinants of performance as coordination. Considering that field sports generally include sprints with change direction over short distance, MAT seems to be more specific than the T-test when assessing agility. PMID:19675502

Sassi, Radhouane Haj; Dardouri, Wajdi; Yahmed, Mohamed Haj; Gmada, Nabil; Mahfoudhi, Mohamed Elhedi; Gharbi, Zied

2009-09-01

84

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

85

Simultaneous genetic analysis of means and covariance structure: Pearson-Lawley selection rules.

The object of this paper is to indicate that the Pearson-Lawley selection rules form a plausible general theory for the simultaneous genetic analysis of means and covariance structure. Models are presented based on phenotypic selection and latent selection. Previously presented quantitative genetic models to decompose means and covariance structure simultaneously are reconsidered as instances of latent selection. The selection rules are very useful in the context of behavior genetic modeling because they lead to testable models and a conceptual framework for explaining variation between and within groups by the same genetic and environmental factors. PMID:8192617

Dolan, C V; Molenaar, P C; Boomsma, D I

1994-01-01

86

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

87

Abstract The primary stability of a dental implant is fundamental for the osseointegration. Therefore, the aim of this study was to assess the correlation between insertion torque (IT) and resonance frequency analysis (RFA) of implants placed in the mandible and maxilla of different bone densities. Eighty dental implants were placed in the maxilla and mandible 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 (1985). The Type I and II densities were grouped together (Group A) and Type III and IV densities in another group (Group B). The IT in Group A was higher (student-t Test, p=0.0013) than IT in Group B (46.27 + 18.51 N/cm, 33.62 + 14.74 N/cm, respectively). The implants placed in Group A showed higher ISQ (student-t Test, p=0.0004) 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= 0.0213) and for Group B (r= 0.37; p= 0.0224). Within the limitations of this study, it was possible to conclude that there is a correlation between IT and RFA of implants placed in the mandible and maxilla of different bone densities. PMID:22506559

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

2012-04-16

88

Improving standards in brain-behavior correlation analyses

Associations between two variables, for instance between brain and behavioral measurements, are often studied using correlations, and in particular Pearson correlation. However, Pearson correlation is not robust: outliers can introduce false correlations or mask existing ones. These problems are exacerbated in brain imaging by a widespread lack of control for multiple comparisons, and several issues with data interpretations. We illustrate these important problems associated with brain-behavior correlations, drawing examples from published articles. We make several propositions to alleviate these problems.

Rousselet, Guillaume A.; Pernet, Cyril R.

2012-01-01

89

A modified weighted function method for parameter estimation of Pearson type three distribution

NASA Astrophysics Data System (ADS)

this paper, an unconventional method called Modified Weighted Function (MWF) is presented for the conventional moment estimation of a probability distribution function. The aim of MWF is to estimate the coefficient of variation (CV) and coefficient of skewness (CS) from the original higher moment computations to the first-order moment calculations. The estimators for CV and CS of Pearson type three distribution function (PE3) were derived by weighting the moments of the distribution with two weight functions, which were constructed by combining two negative exponential-type functions. The selection of these weight functions was based on two considerations: (1) to relate weight functions to sample size in order to reflect the relationship between the quantity of sample information and the role of weight function and (2) to allocate more weights to data close to medium-tail positions in a sample series ranked in an ascending order. A Monte-Carlo experiment was conducted to simulate a large number of samples upon which statistical properties of MWF were investigated. For the PE3 parent distribution, results of MWF were compared to those of the original Weighted Function (WF) and Linear Moments (L-M). The results indicate that MWF was superior to WF and slightly better than L-M, in terms of statistical unbiasness and effectiveness. In addition, the robustness of MWF, WF, and L-M were compared by designing the Monte-Carlo experiment that samples are obtained from Log-Pearson type three distribution (LPE3), three parameter Log-Normal distribution (LN3), and Generalized Extreme Value distribution (GEV), respectively, but all used as samples from the PE3 distribution. The results show that in terms of statistical unbiasness, no one method possesses the absolutely overwhelming advantage among MWF, WF, and L-M, while in terms of statistical effectiveness, the MWF is superior to WF and L-M.

Liang, Zhongmin; Hu, Yiming; Li, Binquan; Yu, Zhongbo

2014-04-01

90

Group sequential t-test for clinical trials with small sample sizes across stages

Interim analyses are often applied in clinical trials for various reasons. To assess the effect of a clinical treatment, the group sequential t-test with a fixed number of interim analyses is frequently used in clinical trials. The existing critical values used in group sequential t-tests are obtained from normal approximations of t-statistics. In practice, however, normal approximation is not accurate

Jun Shao; Huaibao Feng

2007-01-01

91

The standard error in an independent-groups t test is usually derived assuming that individuals are randomly sampled from populations of infinite size. However, t tests are routinely used in randomized experiments with individuals obtained from convenience samples. In such cases, the use of a t test is most often justified by supposing (a) that the convenience sample was a random

Charles S. Reichardt; Harry F. Gollob

1999-01-01

92

ERIC Educational Resources Information Center

Based on seminal work by Lord and Hambleton, Swaminathan, and Rogers, this article is an analytical, graphical, and conceptual reminder that item response theory (IRT) parameter invariance only holds for perfect model fit in multiple populations or across multiple conditions and is thus an ideal state. In practice, one attempts to quantify the…

Rupp, Andre A.; Zumbo, Bruno D.

2004-01-01

93

Pearson disease is a rare, usually fatal, mitochondrial disorder affecting primarily the bone marrow and the exocrine pancreas. We report a previously healthy 10-week-old girl who presented with profound macrocytic anemia followed by pancytopenia, synthetic liver dysfunction with liver steatosis, and metabolic acidosis with high lactate levels. She had no pancreatic involvement. Multiple cytoplasmic vacuoles in myelocytes and monocytes were seen upon microscopic evaluation of the bone marrow. Genetic analysis of the mitochondrial genome revealed a 5 kbp deletion, thus establishing the diagnosis of Pearson disease. PMID:23588341

Shapira, Adi; Konopnicki, Muriel; Hammad-Saied, Mohammed; Shabad, Evelyn

2014-07-01

94

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

95

Energy-efficient routing for wireless sensor networks (WSNs) has been a topic of great interest for the last few years, but thus far routing for signal detection in WSNs has not attracted much attention. In particular, little research has focused on the Neyman-Pearson criterion which is the most well accepted metric for radar, sonar and related signal detection problems. In this

Yang Yang; Rick S. Blum

2007-01-01

96

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

97

A Spreadsheet Tool for Learning the Multiple Regression F-Test, T-Tests, and Multicollinearity

ERIC Educational Resources Information Center

This note presents a spreadsheet tool that allows teachers the opportunity to guide students towards answering on their own questions related to the multiple regression F-test, the t-tests, and multicollinearity. The note demonstrates approaches for using the spreadsheet that might be appropriate for three different levels of statistics classes,…

Martin, David

2008-01-01

98

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

99

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

100

T.E.S.T.S. (Taking Every Student to Success): Another Way To Assess.

ERIC Educational Resources Information Center

This article on the T.E.S.T.S. (Taking Every Student To Success) strategy promotes using a variety of assessment strategies in order to alleviate the stress students experience during exams, enabling those who are not "good test takers" to achieve a higher degree of success. If the primary purpose of giving a test is to determine whether or not a…

McDaniel, Lindy C.

101

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

102

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 randomization was a public middle school. The bootstrap estimate indicated that expectancies explained 21% of the variability in students’ intentions (r = 0.46, 95% CI = [0.40, 0.50]). This case study illustrates the use of a nonparametric bootstrap with cluster randomized data and the danger posed if outliers are not identified and addressed. Editors’ Strategic Implications: Prevention researchers will benefit from the authors’ detailed description of this nonparametric bootstrap approach for cluster randomized data and their thoughtful discussion of the potential impact of cluster sizes and outliers.

Elek, Elvira; Kulis, Stephen; Marsiglia, Flavio

2009-01-01

103

A Pearson Effective Potential model for including quantization effects in the\\u000asimulation of nanoscale nMOSFETs has been developed. This model, based on a\\u000arealistic description of the function representing the non zero-size of the\\u000aelectron wave packet, has been used in a Monte-Carlo simulator for bulk, single\\u000agate SOI and double-gate SOI devices. In the case of SOI capacitors, the

M.-A. Jaud; S. Barraud; P. Dollfus; H. Jaouen

2008-01-01

104

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

105

t-tests, non-parametric tests, and large studies--a paradox of statistical practice?

Background During the last 30 years, the median sample size of research studies published in high-impact medical journals has increased manyfold, while the use of non-parametric tests has increased at the expense of t-tests. This paper explores this paradoxical practice and illustrates its consequences. Methods A simulation study is used to compare the rejection rates of the Wilcoxon-Mann-Whitney (WMW) test and the two-sample t-test for increasing sample size. Samples are drawn from skewed distributions with equal means and medians but with a small difference in spread. A hypothetical case study is used for illustration and motivation. Results The WMW test produces, on average, smaller p-values than the t-test. This discrepancy increases with increasing sample size, skewness, and difference in spread. For heavily skewed data, the proportion of p<0.05 with the WMW test can be greater than 90% if the standard deviations differ by 10% and the number of observations is 1000 in each group. The high rejection rates of the WMW test should be interpreted as the power to detect that the probability that a random sample from one of the distributions is less than a random sample from the other distribution is greater than 50%. Conclusions Non-parametric tests are most useful for small studies. Using non-parametric tests in large studies may provide answers to the wrong question, thus confusing readers. For studies with a large sample size, t-tests and their corresponding confidence intervals can and should be used even for heavily skewed data.

2012-01-01

106

Risk stratification with a point-of-care cardiac troponin T test in acute myocardial infarction

Troponin T has been used successfully to risk stratify patients with acute coronary syndromes, but the utility of this approach using a rapid bedside assay in patients undergoing thrombolysis for ST-segment elevation acute myocardial infarction has not been assessed in a large population. We assessed whether a point-of-care, qualitative troponin T test at enrollment could independently risk-stratify patients randomized to

E. Magnus Ohman; Paul W Armstrong; Harvey D White; Christopher B Granger; Robert G Wilcox; W. Douglas Weaver; W. Brian Gibler; Amanda L Stebbins; Cresha Cianciolo; Robert M Califf; Eric J Topol

1999-01-01

107

The Efficiency of Some Nonparametric Competitors of the $t$Test

Consider samples from continuous distributions $F(x)$ and $F(x - \\\\theta)$. We may test the hypothesis $\\\\theta = 0$ by using the two-sample Wilcoxon test. We show in Section 1 that its asymptotic Pitman efficiency, relative to the $t$-test, never falls below 0.864. This result also holds for the Kruskal-Wallis test compared with the $F$-test, and for testing the location parameter

J. L. Hodges; E. L. Lehmann

1956-01-01

108

When t-tests or Wilcoxon-Mann-Whitney tests won't do

NSDL National Science Digital Library

t-Tests are widely used by researchers to compare the average values of a numeric outcome between two groups. If there are doubts about the suitability of the data for the requirements of a t-test, most notably the distribution being non-normal, the Wilcoxon-Mann-Whitney test may be used instead. However, although often applied, both tests may be invalid when discrete and/or extremely skew data are analyzed. In medicine, extremely skewed data having an excess of zeroes are often observed, representing a numeric outcome that does not occur for a large percentage of cases (so is often zero) but which also sometimes takes relatively large values. For data such as this, application of the t-test or Wilcoxon-Mann-Whitney test could lead researchers to draw incorrect conclusions. A valid alternative is regression modeling to quantify the characteristics of the data. The increased availability of software has simplified the application of these more complex statistical analyses and hence facilitates researchers to use them. In this article, we illustrate the methodology applied to a comparison of cyst counts taken from control and steroid-treated fetal mouse kidneys.

Fiona McElduff (University College London); Mario Cortina-Borja (University College London); Shun-Kai Chan (University College London); Angie Wade (University College London)

2010-09-01

109

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

110

Student's one-sample t-test is a commonly used method when inference about the population mean is made. As advocated in textbooks and articles, the assumption of normality is often checked by a preliminary goodness-of-fit (GOF) test. In a paper recently published by Schucany and Ng it was shown that, for the uniform distribution, screening of samples by a pretest for normality leads to a more conservative conditional Type I error rate than application of the one-sample t-test without preliminary GOF test. In contrast, for the exponential distribution, the conditional level is even more elevated than the Type I error rate of the t-test without pretest. We examine the reasons behind these characteristics. In a simulation study, samples drawn from the exponential, lognormal, uniform, Student's t-distribution with 2 degrees of freedom (t(2) ) and the standard normal distribution that had passed normality screening, as well as the ingredients of the test statistics calculated from these samples, are investigated. For non-normal distributions, we found that preliminary testing for normality may change the distribution of means and standard deviations of the selected samples as well as the correlation between them (if the underlying distribution is non-symmetric), thus leading to altered distributions of the resulting test statistics. It is shown that for skewed distributions the excess in Type I error rate may be even more pronounced when testing one-sided hypotheses. PMID:21973094

Rochon, Justine; Kieser, Meinhard

2011-11-01

111

Objectives The aim of this study was to determine the correlation between increasing pulmonary embolism thrombus load and right ventricular (RV) dilatation as demonstrated by CT pulmonary angiography (CTPA) and to assess the thrombus load threshold which indicates impending RV decompensation. Methods 2425 consecutive CTPAs were retrospectively analysed. Thrombus load using a modified Miller score (MMS), RV to left ventricular (RV:LV) ratio, presence of septal shift, and pulmonary artery and aorta size were analysed in 504 positive CTPA scans and a representative cohort of 100 negative scans. Results were correlated using non-parametric analysis (two-tailed t-test or ?2 test) and Pearson’s rank correlation. Results Increasing thrombus load correlated with a higher RV:LV ratio, with a statistically significant difference in RV:LV ratios between the negative and positive pulmonary embolism (PE) cohorts. Larger thrombus loads (MMS ?12 vs MMS <12) were strongly correlated with RV strain (mean RV:LV ratio, 1.323 vs 0.930; p<0.0001). Smaller thrombus loads had no significant influence on RV strain. Septal shift was also more likely with an MMS of ?12, as was an increase in pulmonary artery diameter (r=0.221, p<0.001). Conclusion With increasing thrombus load in PE, there is CTPA evidence of RV decompensation with an MMS threshold of 12. This suggests a “tipping point” beyond which RV decompensation is more likely to occur. This is the first study to describe this tipping point between a thrombus load of MMS >12 and an increase in RV:LV ratio. This finding may help to improve risk stratification in patients with acute PE diagnosed by CTPA.

Wong, L F; Akram, A R; Mcgurk, S; Van Beek, E J R; Reid, J H; Murchison, J T

2012-01-01

112

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.

Lakens, Daniel

2013-01-01

113

A Comparison of Six Robust Correlation Estimators.

ERIC Educational Resources Information Center

A Monte Carlo investigation of six robust correlation estimators was conducted for data from distributions with longer than Gaussian tails: a bisquare coefficient, the Tukey correlation, the standardized sums and differences, a biweight standardized sums and differences, the transformed Spearman's rho and a bivariate trimmed Pearson. Evaluation of…

Baranowski, B. Bonnie; Halperin, Silas

114

Correlation as Probability of Common Descent.

ERIC Educational Resources Information Center

One interpretation of the Pearson product-moment correlation ("r"), correlation as the probability of originating from common descent, important to the genetic measurement of inbreeding, is examined. The conditions under which "r" can be interpreted as the probability of "identity by descent" are specified, and the possibility of generalizing this…

Falk, Ruma; Well, Arnold D.

1996-01-01

115

Improving regions of deviation gait symmetry analysis with pointwise T tests.

The regions of deviation method has been proposed as a technique for identifying regions of the gait cycle where joint motion deviates from normal (Shorter et al., 2008). The original statistical analysis distinguished only peak values during stance and swing. In the current article, we extend the approach by examining deviations from normal throughout the entire gait cycle using pointwise t tests. These methods were demonstrated on hind-limb joint angles of 21 Labrador Retrievers without and with cranial cruciate ligament disease. Results were compared with peak difference analysis previously performed on these subjects. All points in the gait cycle where symmetry deviations were significantly affected by cranial cruciate ligament disease (via pointwise t tests) were defined as regions of deviation from symmetry. Discriminant function analysis was used to consider single subjects and validate that these regions were truly areas of difference between groups. Regions of deviation encompassed previously determined significant peak differences, while extending analysis to additional areas of asymmetry. Discriminant function analysis suggested that the region of deviation method is a viable approach for distinguishing motion pattern differences. This enhanced method may help researchers better understand the mechanisms behind lameness and compensation. PMID:22723119

DiBerardino, Louis A; Ragetly, Chantal A; Hong, Sungjin; Griffon, Dominique J; Hsiao-Wecksler, Elizabeth T

2012-05-01

116

Independent Samples t-Test: Chips AhoyÃÂ® vs. Supermarket Brand

NSDL National Science Digital Library

In this hands-on activity, created by Dex Whittinghill of Rowan University, students count the number of chips in cookies in order to carry out an independent samples t-test to see if Chips AhoyÃÂ® cookies have a higher, lower, or different mean number of chips per cookie than a supermarket brand. First there is a class discussion that can include concepts about random samples, independence of samples, recently covered tests, comparing two parameters with null and alternative hypotheses, what it means to be a chip in a cookie, how to break up the cookies to count chips, and of course a class consensus on the hypotheses to be tested. Second the students count the number of chips in a one cookie from each brand, and report their observations to the instructor. Third, the instructor develops the independent sample t-test statistic. Fourth, the students carry out (individually or as a class) the hypothesis test, checking the assumptions on sample-size/population-shape.

Whittinghill, Dex

2009-07-23

117

This paper deals with the constant false alarm rate (CFAR) radar detection of targets embedded in Pearson distributed clutter.\\u000a We develop new CFAR detection algorithms-notably cell averaging (CA), greatest of selection (GO) and smallest of selection\\u000a SO-CFAR operating in Pearson measurements based on a non-linear compression method for spiky clutter reduction. The technique\\u000a is similar to that used in non

Z. Messali; Faouzi Soltani; Mohamed Sahmoudi

2008-01-01

118

NASA Astrophysics Data System (ADS)

The application of supervised learning machines trained to minimize the Cross-Entropy error to radar detection is explored in this article. The detector is implemented with a learning machine that implements a discriminant function, which output is compared to a threshold selected to fix a desired probability of false alarm. The study is based on the calculation of the function the learning machine approximates to during training, and the application of a sufficient condition for a discriminant function to be used to approximate the optimum Neyman-Pearson (NP) detector. In this article, the function a supervised learning machine approximates to after being trained to minimize the Cross-Entropy error is obtained. This discriminant function can be used to implement the NP detector, which maximizes the probability of detection, maintaining the probability of false alarm below or equal to a predefined value. Some experiments about signal detection using neural networks are also presented to test the validity of the study.

Jarabo-Amores, María-Pilar; la Mata-Moya, David de; Gil-Pita, Roberto; Rosa-Zurera, Manuel

2013-12-01

119

Background The purpose of the present study was to evaluate the prognostic value of POSTN expression following prostatectomy. Methods Periostin (POSTN) expression in prostate cancer (PCa) and in normal specimens was evaluated in 90 patients by an immuno-reactive score(IRS) based on the intensity of immunostaining and on the quantity of stained cells. The t-test was applied to compare IRS values in cancer specimens to values in normal specimens. Pearson’s test was used to correlate POSTN expression to clinical pathologic features. PSA progression-free and survival curves were constructed by the Kaplan–Meier method and compared using the log-rank test. Multi-parametric models were constructed according to the Cox technique adding all the covariates predicting for either PSA progression or death into the models after univariate analysis. Results Both stromal and epithelial POSTN expression were significantly increased in tumor tissues. In particular, we found stromal expression to be significantly higher than epithelial expression as compared to normal tissues (p<0.000 and p=0.001).A significant correlation between POSTN epithelial expression and extra-prostatic extension was found (p=0.03). While high stromal expression was significantly associated with shorter survival (p=0.008), a low epithelial score significantly correlated with shorter PSA-free survival (p=0.04), suggesting that POSTN plays an apparently opposing biological role depending on its compartmentalization.Regardless of the mechanism that is involved, patients showing both high stromal and low epithelial expression made up a subgroup with a very bleak prognosis. Conclusions Although requiring further validation through larger studies, our findings show that POSTN might represent a novel prognostic marker for PCa.

2012-01-01

120

Simultaneous Critical Values For T-Tests In Very High Dimensions

This article considers the problem of multiple hypothesis testing using t-tests. The observed data are assumed to be independently generated conditional on an underlying and unknown two-state hidden model. We propose an asymptotically valid data-driven procedure to find critical values for rejection regions controlling k-family wise error rate (k-FWER), false discovery rate (FDR) and the tail probability of false discovery proportion (FDTP) by using one-sample and two-sample t-statistics. We only require finite fourth moment plus some very general conditions on the mean and variance of the population by virtue of the moderate deviations properties of t-statistics. A new consistent estimator for the proportion of alternative hypotheses is developed. Simulation studies support our theoretical results and demonstrate that the power of a multiple testing procedure can be substantially improved by using critical values directly as opposed to the conventional p-value approach. Our method is applied in an analysis of the microarray data from a leukemia cancer study that involves testing a large number of hypotheses simultaneously.

Cao, Hongyuan; Kosorok, Michael R.

2010-01-01

121

National Technical Information Service (NTIS)

A discussion is made of nonparametric versus parametric methods for the estimation of probability densities. A new algorithm for nonparametric density estimation is given and its performance compared with state-of-the-art kernel estimation algorithms. (Au...

D. W. Scott R. A. Tapia J. R. Thompson

1978-01-01

122

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

123

Investigation of Some Correlates and Predictors of Trust in Two Department of Defense Organizations.

National Technical Information Service (NTIS)

This thesis analyzes the relationship between interpersonal trust and other relevant attitudinal variables identified in the management literature. Pearson's coefficient of correlation was used to measure the relationship between trust and group cohesion,...

J. L. Krizsa

1983-01-01

124

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

Ammendola, Michele; Sacco, Rosario; Sammarco, Giuseppe; Donato, Giuseppe; Zuccalà, Valeria; Luposella, Maria; Patruno, Rosa; Marech, Ilaria; Montemurro, Severino; Zizzo, Nicola; Gadaleta, Cosmo Damiano; Ranieri, Girolamo

2014-01-01

125

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.

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

2014-01-01

126

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

127

In brief, the Henderson, Pearson, and Siliciano casebook includes materials on ethics, problems and other skill-based activities, a diverse set of ideological perspectives presented in a non-preachy way, and addresses numerous real-world issues and concerns. The casebook also lends itself to the variety of teaching and active learning methods I employ in my Torts classes.

Lynn M. Daggett

2001-01-01

128

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

129

Combining Correlation Matrices: Simulation Analysis of Improved Fixed-Effects Methods

ERIC Educational Resources Information Center

The originally proposed multivariate meta-analysis approach for correlation matrices--analyze Pearson correlations, with each study's observed correlations replacing their population counterparts in its conditional-covariance matrix--performs poorly. Two refinements are considered: Analyze Fisher Z-transformed correlations, and substitute better…

Hafdahl, Adam R.

2007-01-01

130

ERIC Educational Resources Information Center

The Pearson correlation is used to depict effect sizes in the context of item response theory. Amultidimensional Rasch model is used to directly estimate the correlation between latent traits. Monte Carlo simulations were conducted to investigate whether the population correlation could be accurately estimated and whether the bootstrap method…

Wang, Wen-Chung

2004-01-01

131

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

132

Factors That Attenuate the Correlation Coefficient and Its Analogs.

ERIC Educational Resources Information Center

The correlation coefficient is an integral part of many other statistical techniques (analysis of variance, t-tests, etc.), since all analytic methods are actually correlational (G. V. Glass and K. D. Hopkins, 1984). The correlation coefficient is a statistical summary that represents the degree and direction of relationship between two variables.…

Dolenz, Beverly

133

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.

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

134

Some Properties of the Correlation Matrix of Dichotomous Guttman Items.

ERIC Educational Resources Information Center

Properties of dichotomous Guttman-scalable items are described. Both the elements and eigenvalues of the Pearson correlation matrix of such items can be expressed as simple functions of the number of items if the score distribution is uniform and there is an equal number of items at each difficulty level. (SLD)

Zwick, Rebecca

1988-01-01

135

Understanding Correlation: Factors that Affect the Size of r

ERIC Educational Resources Information Center

The authors describe and illustrate 6 factors that affect the size of a Pearson correlation: (a) the amount of variability in the data, (b) differences in the shapes of the 2 distributions, (c) lack of linearity, (d) the presence of 1 or more "outliers," (e) characteristics of the sample, and (f) measurement error. Also discussed are ways to…

Goodwin, Laura D.; Leech, Nancy L.

2006-01-01

136

Effect of degree correlations above the first shell on the percolation transition

NASA Astrophysics Data System (ADS)

The use of degree-degree correlations to model realistic networks which are characterized by their Pearson's coefficient, has become widespread. However the effect on how different correlation algorithms produce different results on processes on top of them, has not yet been discussed. In this letter, using different correlation algorithms to generate assortative networks, we show that for very assortative networks the behavior of the main observables in percolation processes depends on the algorithm used to build the network. The different alghoritms used here introduce different inner structures that are missed in Pearson's coefficient. We explain the different behaviors through a generalization of Pearson's coefficient that allows to study the correlations at chemical distances l from a root node. We apply our findings to real networks.

Valdez, L. D.; Buono, C.; Braunstein, L. A.; Macri, P. A.

2011-11-01

137

Decorrelate hyperspectral images using spectral correlation

NASA Astrophysics Data System (ADS)

This paper proposes a new algorithm for lossless compression of hyperspectral images. In our work we found hyperspectral data have unique characteristic based on spectral context and adjacent pixel spectral vectors (curves) highly correlate with each other. Pearson correlation coefficient is an effective measure of spectral similarity between spectral curves to detect horizontal and vertical spectral edge. Thus, spectral correlation is used to prediction in spectral direction for decorrelation of lossless compression of hyperspectral images. Experiments show the proposed algorithm is effective, and it's more important that it has much lower complexity than other algorithms.

Chen, Liang; Liu, Daizhi; Huang, Shiqi

2007-01-01

138

Coronary heart disease (CHD) is still the leading cause of death for adults worldwide. Traditional Chinese medicine (TCM) has a history of 1000 years fighting against the disease and provides a complementary and alternative treatment to it. Syndrome is the core of TCM diagnosis and it is traditionally diagnosed based on macroscopic symptoms as well as tongue and pulse recognitions of patients. Establishment of the diagnosis method in the microcosmic level is an urgent and major problem in TCM. The aim of this study was to establish characteristic diagnosis pattern for CHD with Qi deficiency syndrome (QDS). Thirty-four biological parameters were detected in 52 patients having unstable angina (UA) with or without QDS. Then, we presented a novel data mining method, t-test-based Adaboost algorithm, to establish highest prediction accuracy with the least number of biological parameters for UA with QDS. We gained a pattern composed of five biological parameters that distinguishes UA with QDS patients from non-QDS patients. The diagnosis accuracy of the patterns could reach 84.5% based on a 3-fold cross validation technique. Moreover, we included 85 UA cases collected from hospitals located in the north and south of China to further verify the association between the pattern and QDS. The classification accuracy is 83.5%, which keeps consistent with the accuracy obtained by the cross-validation technique. The association between a symptom and the five biological parameters was established by the data mining method and it reached an accuracy of ?80%. These results showed that the t-test-based Adaboost algorithm might be a powerful technique for diagnosing syndrome in TCM in the context of CHD.

Zhao, Huihui; Chen, Jianxin; Hou, Na; Zhang, Peng; Wang, Yong; Han, Jing; Hou, Qin; Qi, Qige; Wang, Wei

2011-01-01

139

Distance Correlation Methods for Discovering Associations in Large Astrophysical Databases

NASA Astrophysics Data System (ADS)

High-dimensional, large-sample astrophysical databases of galaxy clusters, such as the Chandra Deep Field South COMBO-17 database, provide measurements on many variables for thousands of galaxies and a range of redshifts. Current understanding of galaxy formation and evolution rests sensitively on relationships between different astrophysical variables; hence an ability to detect and verify associations or correlations between variables is important in astrophysical research. In this paper, we apply a recently defined statistical measure called the distance correlation coefficient, which can be used to identify new associations and correlations between astrophysical variables. The distance correlation coefficient applies to variables of any dimension, can be used to determine smaller sets of variables that provide equivalent astrophysical information, is zero only when variables are independent, and is capable of detecting nonlinear associations that are undetectable by the classical Pearson correlation coefficient. Hence, the distance correlation coefficient provides more information than the Pearson coefficient. We analyze numerous pairs of variables in the COMBO-17 database with the distance correlation method and with the maximal information coefficient. We show that the Pearson coefficient can be estimated with higher accuracy from the corresponding distance correlation coefficient than from the maximal information coefficient. For given values of the Pearson coefficient, the distance correlation method has a greater ability than the maximal information coefficient to resolve astrophysical data into highly concentrated horseshoe- or V-shapes, which enhances classification and pattern identification. These results are observed over a range of redshifts beyond the local universe and for galaxies from elliptical to spiral.

Martínez-Gómez, Elizabeth; Richards, Mercedes T.; Richards, Donald St. P.

2014-01-01

140

ERIC Educational Resources Information Center

In 2 Monte Carlo studies of fixed- and random-effects meta-analysis for correlations, A. P. Field (2001) ostensibly evaluated Hedges-Olkin-Vevea Fisher-[zeta] and Schmidt-Hunter Pearson-r estimators and tests in 120 conditions. Some authors have cited those results as evidence not to meta-analyze Fisher-[zeta] correlations, especially with…

Hafdahl, Adam R.; Williams, Michelle A.

2009-01-01

141

Objective To describe the prevalence and clinical correlates of endoscopic gastric antral vascular ectasia (GAVE; “watermelon stomach”) in early diffuse systemic sclerosis (SSc). Methods Subjects with early, diffuse SSc and evidence of specific internal organ involvement were considered for the Scleroderma: Cyclophosphamide Or Transplant (SCOT) trial. In the screening procedures, all patients underwent upper gastrointestinal endoscopy. Patients were then categorized into those with or without endoscopic evidence of GAVE. Demographic data, clinical disease characteristics, and autoantibody data were compared using Pearson chi-square or Student t tests. Results Twenty-three of 103 (22.3%) individuals were found to have GAVE on endoscopy. Although not statistically significant, anti-topoisomerase I (anti-Scl70) was detected less frequently among those with GAVE (18.8% vs 44.7%; p = 0.071). Similarly, anti-RNP antibodies (anti-U1 RNP) showed a trend to a negative association with GAVE (0 vs 18.4%; p = 0.066). There was no association between anti-RNA polymerase III and GAVE. Patients with GAVE had significantly more erythema or vascular ectasias in other parts of the stomach (26.1% vs 5.0%; p = 0.003). Conclusion Endoscopic GAVE was present on screening in almost one-fourth of these highly selected patients with early and severe diffuse SSc. While anti-Scl70 and anti-U1 RNP trended toward a negative association with GAVE, there was no correlation between anti-RNA Pol III and GAVE. Patients with GAVE had a higher frequency of other gastric vascular ectasias outside the antrum, suggesting that GAVE may represent part of the spectrum of the vasculopathy in SSc.

Hung, Emily W.; Mayes, Maureen D.; Sharif, Roozbeh; Assassi, Shervin; Machicao, Victor I.; Hosing, Chitra; St. Clair, E. William; Furst, Daniel E.; Khanna, Dinesh; Forman, Stephen; Mineishi, Shin; Phillips, Kristine; Seibold, James R.; Bredeson, Christopher; Csuka, Mary Ellen; Nash, Richard A.; Wener, Mark H.; Simms, Robert; Ballen, Karen; Leclercq, Sharon; Storek, Jan; Goldmuntz, Ellen; Welch, Beverly; Keyes-Elstein, Lynette; Castina, Sharon; Crofford, Leslie J.; Mcsweeney, Peter; Sullivan, Keith M.

2013-01-01

142

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

143

Using Taylor series, series for the first four moments of the standardized sample standard deviation and the sample skewness from Gamma populations are studied; the series, using a computer approach, are taken out to terms of order n/sup -24/ (n the sample size) for the standard deviation, and n/sup -12/ for the skewness. Summation techniques are required for the apparent divergency encountered; Pade (near the main diagonal in the table) and Levin algorithms are used. Although the latter seems to be weakly divergent, a best stopping member of a sequence can be located by comparison with exact results for n = 2 and n = 3. The study is a continuation of theoretical and numerical work undertaken by Cecil Craig and Egon S. Pearson half-a-century ago. Comparisons are made with extended moment series, first of all for the moments, and secondly, for 4-moment distributional approximants. As backup assessments, simulation results in a few cases are given.

Bowman, K.O.; Shenton, L.R.

1983-01-01

144

National Technical Information Service (NTIS)

Coherent optical correlators, classified as spatial plane correlators, frequency plane correlators, and special reference correlators, are examined. Basic principles, advantages, and disadvantages are discussed, and comparisons made with incoherent correl...

J. A. Boden

1974-01-01

145

Odontometric Sexual Dimorphism: A Sibling Correlation

Aims and Background: Teeth form an excellent material for anthropological, genetic, odontologic and forensic investigations. The aim of this study was to establish the genetic control of sexual dimorphism in tooth size amongst siblings of Goan children in age range of 14-22 years. Materials and Methods: Twenty-two sibling pairs were selected (22 males and 22 females) to assess genetic control of sexual dimorphism in tooth size. Alginate impressions were obtained for maxillary and mandibular arches and study models were prepared. Measurements were done using Zoom Digimatic Vernier Calipers with a resolution of 0.01 mm. Statistical Analysis: Correlation between mesiodistal and buccolingual tooth sizes amongst siblings was calculated using Pearson’s correlation coefficient. Results: A statistically significant association was found between Mesiodistal Widths of Permanent Maxillary Right and Left Second Molars and between Maxillary Right and Left First Premolars amongst sibling pairs. A statistically significant association was also found between Buccolingual Widths of Mandibular Right and Left First Premolars amongst sibling pairs. This statistically significant correlation found amongst siblings establishes a genetic control over sexual dimorphism in these teeth. Conclusion: The genetic basis of sexual dimorphism in human dentition was ascertained as a significant correlation was found between mesio-distal and bucco-lingual widths of premolars between sibling pairs.

Sharma, Sonali; Dinkar, Ajit D.; Bedi, Sumit

2014-01-01

146

Correlates of Frailty Among Homeless Adults

Frailty, a relatively unexplored concept among vulnerable populations, may be a significant issue for homeless adults. This cross-sectional study assessed correlates of frailty among middle age and older homeless adults (N = 150, 40–73). A Pearson (r) bivariate correlation revealed a weak relationship between frailty and being female (r = .230, p < .01). Significant moderate negative correlations were found between frailty and resilience (r = ?.395, p < .01), social support (r = ?.377, p < .01), and nutrition (r = ?.652, p < .01). Furthermore, Spearman’s rho (rs) bivariate correlations revealed a moderate positive relationship between frailty and health care utilization (rs = .444, p < .01). A stepwise backward linear regression analysis was conducted and in the final model, age, gender, health care utilization, nutrition, and resilience were significantly related to frailty. Over the next two decades, there is an anticipated increase in the number of homeless adults which will necessitate a greater understanding of the needs of this hard-to-reach population.

Salem, Benissa E.; Nyamathi, Adeline M.; Brecht, Mary-Lynn; Phillips, Linda R.; Mentes, Janet C.; Sarkisian, Catherine; Leake, Barbara

2013-01-01

147

In the present study, the internal adaptation of dentin-composite interfaces with various resin composite materials under conditions of thermomechanical loading was analyzed nondestructively using micro-computed tomography (micro-CT), and these results were compared with analyses of microgaps after sectioning. Additionally, the correlation of internal adaptation with polymerization shrinkage strain and stress was evaluated. Four nonflowable resins, Gradia Direct (GD), Filtek P90 (P9), Filtek Z350 (Z3), and Charisma (CH), and two flowable resins, SDR (SD) and Tetric N-Flow (TF) were used. First, the polymerization shrinkage strain and stress were measured. Then, Class I cavities were prepared in 48 premolars. They were divided randomly into six groups, and the cavities were filled with composites using XP bond. To evaluate the internal adaptation, tooth specimens were immersed in a 25% silver nitrate solution, and micro-CT analysis was performed before and after thermomechanical loading. The silver nitrate penetration (%SP) was measured. After buccolingual sectioning and rhodamine penetration of the specimen, the rhodamine penetration (%RP) was measured using a stereo-microscope. One-way analysis of variance was then used to compare the polymerization shrinkage strain, stress, %SP, and %RP among the groups at a 95% confidence level. A paired t-test was used to compare the %SP before and after thermomechanical loading. Pearson correlation analysis was used to compare the correlation between polymerization shrinkage strain/stress and %SP or %RP to a 95% confidence level. Evaluation of the polymerization shrinkage strain demonstrated that P9 < Z3 ? GD < CH ? SD < TF (p<0.05); similarly, evaluation of the polymerization shrinkage stress showed that P9 ? GD ? Z3 ? CH ? SD < TF (p<0.05). The %SP showed that P9 ? GD ? Z3 < CH ? SD < TF (p<0.05) before loading and that P9 ? GD ? Z3 ? CH ? SD < TF (p<0.05) after loading. There was a significant difference between the before-loading and after-loading measurements in all groups (p<0.05). Additionally, there was a positive correlation between the %SP and the %RP (r=0.810, p<0.001). Conclusively, the polymerization shrinkage stress and strain were found to be closely related to the internal adaptation of the resin composite restorations. The newly proposed model for the evaluation of internal adaptation using micro-CT and silver nitrate may provide a new measurement for evaluating the internal adaptation of restorations in a nondestructive way. PMID:24111809

Kim, H J; Park, S H

2014-01-01

148

sample variance, respectively. We refer to Tn as the central or non-central (Student's) t-statistic, depending on whether EX ¼ 0o r EX 6¼ 0, respectively. The non-central t-statistic arises naturally in the calculation of powers for t-tests. The central t-statistic has been well studied, while there is a very limited literature on the non-central t-statistic. In this paper, we attempt

VIDMANTAS B ENTKUS; BING-YI J ING; QI-MAN SHAO; WANG ZHOU

2007-01-01

149

Taking serial correlation into account in tests of the mean.

National Technical Information Service (NTIS)

The comparison of means derived from samples of noisy data is a standard part of climatology. When the data are not serially correlated the appropriate statistical tool for this task is usually the conventional Student's t-test. However, data frequently a...

F. W. Zwiers H. Storch

1993-01-01

150

ERIC Educational Resources Information Center

Besides the ubiquitous Pearson product-moment r, there are a number of other measures of relationship that are attenuated by errors of measurement and for which the relationship between true measures can be estimated. Among these are the correlation ratio (eta squared), Kelley's unbiased correlation ratio (epsilon squared), Hays' omega squared,…

Stanley, Julian C.; Livingston, Samuel A.

151

This study aimed to objectively evaluate the radiopacity of different dental composites and their subjective influence on diagnosing secondary caries-like lesions and how these results correlate. For objective analysis, three resin specimens (1 mm thick, with a 4-mm internal diameter) were made with four composites: 1) Charisma; 2) Filtek Z250; 3) Prisma AP.H; and 4) Glacier. Three human teeth were selected and then mesio-distally sectioned (1 mm thick) to make the dental specimens. An aluminum (Al) wedge (12 steps, 1 mm thick, 99.8% purity) was used as an internal standard to calculate the radiopacity. For subjective analysis, 20 human teeth were selected and then prepared with a mesio-occluso-distal (MOD) inlay cavity, with half the teeth receiving a round cavity to simulate the carious lesion. The MOD was restored using the composites at four different times. Standardized radiographs were acquired and then digitized (300 dpi and eight-bit TIFF) for both analyses. A histogram objectively measured the pixel intensity values of the images, which were converted into millimeters of Al using linear regressions. Eight observers subjectively evaluated the images using a five-point rating scale to diagnose the caries. The data were statistically analyzed using the Student t-test, the Kappa test, diagnostic testing, and the Pearson correlation coefficient (?=0.05). All materials showed radiopacity values compatible with dental tissues (p>0.05); Glacier was similar to dentin and Prisma AP.H was similar to enamel, while the remaining materials showed a middle radiopacity. Prisma AP.H and Glacier differed (p<0.05) in relation to their accuracy to caries diagnosis, with Glacier having greater accuracy. There was a correlation between objective and subjective analyses with negative linear dependence. An increase in the material's radiopacity could have a subjectively negative influence on the diagnosis of secondary caries; thus, an ideal radiopacity for a dental composite is closer to the dentin image and produces similar attenuation to X-rays than does dentin. PMID:23713807

Cruz, A D; Esteves, R G; Poiate, I A V P; Portero, P P; Almeida, S M

2014-01-01

152

Objectives Indications for cochlear implantation have expanded today to include very young children and those with syndromes/multiple handicaps. Programming the implant based on behavioural responses may be tedious for audiologists in such cases, wherein matching an effective Measurable Auditory Percept (MAP) and appropriate MAP becomes the key issue in the habilitation program. In 'Difficult to MAP' scenarios, objective measures become paramount to predict optimal current levels to be set in the MAP. We aimed to (a) study the trends in multi-modal electrophysiological tests and behavioural responses sequentially over the first year of implant use; (b) generate normative data from the above; (c) correlate the multi-modal electrophysiological thresholds levels with behavioural comfort levels; and (d) create predictive formulae for deriving optimal comfort levels (if unknown), using linear and multiple regression analysis. Methods This prospective study included 10 profoundly hearing impaired children aged between 2 and 7 years with normal inner ear anatomy and no additional handicaps. They received the Advanced Bionics HiRes 90 K Implant with Harmony Speech processor and used HiRes-P with Fidelity 120 strategy. They underwent, impedance telemetry, neural response imaging, electrically evoked stapedial response telemetry (ESRT), and electrically evoked auditory brainstem response (EABR) tests at 1, 4, 8, and 12 months of implant use, in conjunction with behavioural mapping. Trends in electrophysiological and behavioural responses were analyzed using paired t-test. By Karl Pearson's correlation method, electrode-wise correlations were derived for neural response imaging (NRI) thresholds versus most comfortable level (M-levels) and offset based (apical, mid-array, and basal array) correlations for EABR and ESRT thresholds versus M-levels were calculated over time. These were used to derive predictive formulae by linear and multiple regression analysis. Such statistically predicted M-levels were compared with the behaviourally recorded M-levels among the cohort, using Cronbach's alpha reliability test method for confirming the efficacy of this method. Results NRI, ESRT, and EABR thresholds showed statistically significant positive correlations with behavioural M-levels, which improved with implant use over time. These correlations were used to derive predicted M-levels using regression analysis. On an average, predicted M-levels were found to be statistically reliable and they were a fair match to the actual behavioural M-levels. When applied in clinical practice, the predicted values were found to be useful for programming members of the study group. However, individuals showed considerable deviations in behavioural M-levels, above and below the electrophysiologically predicted values, due to various factors. While the current method appears helpful as a reference to predict initial maps in 'difficult to Map' subjects, it is recommended that behavioural measures are mandatory to further optimize the maps for these individuals. Conclusion The study explores the trends, correlations and individual variabilities that occur between electrophysiological tests and behavioural responses, recorded over time among a cohort of cochlear implantees. The statistical method shown may be used as a guideline to predict optimal behavioural levels in difficult situations among future implantees, bearing in mind that optimal M-levels for individuals can vary from predicted values. In 'Difficult to MAP' scenarios, following a protocol of sequential behavioural programming, in conjunction with electrophysiological correlates will provide the best outcomes. PMID:24606544

Raghunandhan, S; Ravikumar, A; Kameswaran, Mohan; Mandke, Kalyani; Ranjith, R

2014-05-01

153

Evaluation of the construct validity of the DASH questionnaire by correlation to the SF36

The construct validity of the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire was evaluated by examining its correlation to the Medical Outcomes Study Short Form–36 (SF-36). The study sample was 90 patients seen at the upper-extremity clinic of a university-based orthopedic practice. Patients were asked to complete a packet that included the DASH and SF-36 questionnaires. Pearson correlation

Nelson Fong SooHoo; Allen P. McDonald; John Gray Seiler; Gary R. McGillivary

2002-01-01

154

Weighted network analysis of high-frequency cross-correlation measures

NASA Astrophysics Data System (ADS)

In this paper we implement a Fourier method to estimate high-frequency correlation matrices from small data sets. The Fourier estimates are shown to be considerably less noisy than the standard Pearson correlation measures and thus capable of detecting subtle changes in correlation matrices with just a month of data. The evolution of correlation at different time scales is analyzed from the full correlation matrix and its minimum spanning tree representation. The analysis is performed by implementing measures from the theory of random weighted networks.

Iori, Giulia; Precup, Ovidiu V.

2007-03-01

155

ERIC Educational Resources Information Center

The purpose of this study was to determine if a correlation existed between the classes of books checked out of the San Antonio College Library and the classes of books used in the Library. Data for out-of-library and in-library use were collected during February, 1978, and arranged by Dewey Decimal Classification (DDC) tens. By using the Pearson…

Domas, Ralph E.

156

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.

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

2013-01-01

157

On the insignificance of Herschel's sunspot correlation

NASA Astrophysics Data System (ADS)

We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is "statistically significant." On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are "insignificant." Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.

Love, Jeffrey J.

2013-08-01

158

Does APO ?4 correlate with MRI changes in Alzheimer's disease?

OBJECTIVE—To assess the relation between APO E genotype and MRI white matter changes in Alzheimer's disease. The APO ?4 allele is correlated with amyloid angiopathy and other neuropathologies in Alzheimer's disease and could be associated with white matter changes. If so, there should be a dose effect.?METHODS—104 patients with probable Alzheimer's disease (NINCDS-ADRDA criteria) in this Alzheimer's Disease Research Centre were studied. Patients received MRI and APO E genotyping by standardised protocols. Axial MRI was scored (modified Schelten's scale) for the presence and degree of white matter changes and atrophy in several regions by a neuroradiologist blinded to genotype. Total white matter and total atrophy scores were also generated. Data analysis included Pearson's correlation for regional and total imaging scores and analysis of variance (ANOVA) (or Kruskal-Wallis) and ?2 for demographic and disease related variables.?RESULTS—30 patients had no ?4, 53 patients were heterozygous, and 21 patients were homozygous. The three groups did not differ in sex distribution, age of onset, age at MRI, MMSE, clinical dementia rating, or modified Hachinski ischaemia scores. There were no significant correlations between total or regional white matter scores and APO E genotype (Pearson correlation).?CONCLUSIONS—No correlation between total or regional white matter scores and APO E genotype was found. The pathogenesis of white matter changes in Alzheimer's disease may be independent of APO E genotype.??

Doody, R; Azher, S; Haykal, H; Dunn, J; Liao, T; Schneider, L

2000-01-01

159

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

160

Collective Correlations of Brodmann Areas fMRI Study with RMT-Denoising

NASA Astrophysics Data System (ADS)

We study collective behavior of Brodmann regions of human cerebral cortex using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory (RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the Brodmann areas with the aid of the Talairach coordinates. Principal Component Analysis (PCA) of the Pearson correlation matrix for 41 different Brodmann regions is carried out to determine their collective activity in the idle state and in the active state stimulated by tapping. The collective brain activity is identified through the statistical analysis of the eigenvectors to the largest eigenvalues of the Pearson correlation matrix. The leading eigenvectors have a large participation ratio. This indicates that several Broadmann regions collectively give rise to the brain activity associated with these eigenvectors. We apply random matrix theory to interpret the underlying multivariate data.

Burda, Z.; Kornelsen, J.; Nowak, M. A.; Porebski, B.; Sboto-Frankenstein, U.; Tomanek, B.; Tyburczyk, J.

161

NASA Technical Reports Server (NTRS)

Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.

Cotariu, Steven S.

1991-01-01

162

The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such {open_quotes}noncausal correlation{close_quotes} is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range {open_quotes}noncausal{close_quotes} correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation. {copyright} {ital 1999} {ital The American Physical Society}

Giraud, B.G. [Service de Physique Theorique, Centre dEtudes de Saclay, 91191 Gif-sur-Yvette (France)] [Service de Physique Theorique, Centre dEtudes de Saclay, 91191 Gif-sur-Yvette (France); Heumann, J.M. [Hewlett Packard Company, Manufacturing Test Division, P.O. Box 301, Loveland, Colorado 80539-0301 (United States)] [Hewlett Packard Company, Manufacturing Test Division, P.O. Box 301, Loveland, Colorado 80539-0301 (United States); Lapedes, A.S. [Theoretical Division, Los Alamos National Laboratory, The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)] [Theoretical Division, Los Alamos National Laboratory, The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)

1999-05-01

163

Pearson's Product-Moment correlation analysis of the relationships between total hydrocarbon content (THC) and hydrocarbon utilizing bacteria population (HUB) in mangrove sediments and overlying water of the Qua Iboe Estuary, Nigeria was carried out. The results show that there was in general a close relationship between the two variables, but also a large amount of variation not explained by the analysis.

Joseph P. Essien; Nsikak U. Benson; Sylvester P. Antai

164

We investigated the association between circulating levels of 60 and 70 kDa heat-shock proteins (HSP60 and 70) and cardiovascular risk factors in postmenopausal women with or without metabolic syndrome (MetS). This cross-sectional study included 311 Brazilian women (age ?45 years with amenorrhea ?12 months). Women showing three or more of the following diagnostic criteria were diagnosed with MetS: waist circumference (WC) ?88 cm, blood pressure ?130/85 mmHg, triglycerides ?150 mg/dl, high-density lipoprotein (HDL) <50 mg/dl, and glucose ?100 mg/dl. Clinical, anthropometric, and biochemical parameters were collected. HSP60, HSP70, antibodies to HSP60 and HSP70, and C-reactive protein (CRP) levels were measured in serum. Student's t test, Kruskal-Wallis test, chi-square test, and Pearson correlation were used for statistical analysis. Of the 311 women, 30.9 % (96/311) were diagnosed with MetS. These women were, on average, obese with abdominal fat deposition and had lower HDL values as well as higher triglycerides and glucose levels. Homeostasis model assessment-insulin resistant (HOMA-IR) test values in these women were compatible with insulin resistance (P?correlation between anti-HSP70 and WC, blood pressure and HOMA-IR, and between CRP and WC, blood pressure, glucose, HOMA-IR, and triglycerides (P?

Nahas, Eliana A P; Nahas-Neto, Jorge; Orsatti, Claudio L; Tardivo, Ana Paula; Uemura, Gilberto; Peraçoli, Maria Terezinha S; Witkin, Steven S

2014-07-01

165

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.

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

2014-01-01

166

Gaussian graphical modeling reveals specific lipid correlations in glioblastoma cells

NASA Astrophysics Data System (ADS)

Advances in high-throughput measurements of biological specimens necessitate the development of biologically driven computational techniques. To understand the molecular level of many human diseases, such as cancer, lipid quantifications have been shown to offer an excellent opportunity to reveal disease-specific regulations. The data analysis of the cell lipidome, however, remains a challenging task and cannot be accomplished solely based on intuitive reasoning. We have developed a method to identify a lipid correlation network which is entirely disease-specific. A powerful method to correlate experimentally measured lipid levels across the various samples is a Gaussian Graphical Model (GGM), which is based on partial correlation coefficients. In contrast to regular Pearson correlations, partial correlations aim to identify only direct correlations while eliminating indirect associations. Conventional GGM calculations on the entire dataset can, however, not provide information on whether a correlation is truly disease-specific with respect to the disease samples and not a correlation of control samples. Thus, we implemented a novel differential GGM approach unraveling only the disease-specific correlations, and applied it to the lipidome of immortal Glioblastoma tumor cells. A large set of lipid species were measured by mass spectrometry in order to evaluate lipid remodeling as a result to a combination of perturbation of cells inducing programmed cell death, while the other perturbations served solely as biological controls. With the differential GGM, we were able to reveal Glioblastoma-specific lipid correlations to advance biomedical research on novel gene therapies.

Mueller, Nikola S.; Krumsiek, Jan; Theis, Fabian J.; Böhm, Christian; Meyer-Bäse, Anke

2011-05-01

167

Anatomic correlates of interhippocampal seizure propagation time.

The relation between interhippocampal seizure propagation time (IHSPT) and anatomic alterations in the human epileptic hippocampus may provide insight into the pathophysiology of temporal lobe epilepsy (TLE). Using depth electrode recordings, we measured the time required for spontaneous seizures with onset in one hippocampus to become manifest in the contralateral hippocampus in 50 patients who underwent resection of the temporal lobe of seizure origin. Cell densities in individual hippocampal subfields were determined and correlated with mean IHSPT for each patient. Mean IHSPT was significantly and inversely correlated with cell counts in CA4 only (r = -0.38, p less than 0.01, Pearson's product correlation; r = -0.52, p less than 0.001, Spearman's rank order correlation). In 5 patients with bilateral independent hippocampal seizure onset who had temporal lobectomy and a diagnosis of mesial temporal sclerosis, mean IHSPT was consistently longer from the sclerotic temporal lobe than to it. These observations suggest that anatomic changes associated with chronic epilepsy alter propagation patterns. Because CA4 is believed to modulate the output of dentate granule cells and also has commissural connections to the contralateral homotopic area, the association of decreased CA4 cells with prolongation of IHSPT suggests that the observed anatomic alterations may actively (through increased inhibition) or passively (through decreased recruitment) interfere with various routes of seizure propagation. PMID:1396429

Spencer, S S; Marks, D; Katz, A; Kim, J; Spencer, D D

1992-01-01

168

Odontometric sexual dimorphism: a sibling correlation.

Aims and Background: Teeth form an excellent material for anthropological, genetic, odontologic and forensic investigations. The aim of this study was to establish the genetic control of sexual dimorphism in tooth size amongst siblings of Goan children in age range of 14-22 years. Materials and Methods: Twenty-two sibling pairs were selected (22 males and 22 females) to assess genetic control of sexual dimorphism in tooth size. Alginate impressions were obtained for maxillary and mandibular arches and study models were prepared. Measurements were done using Zoom Digimatic Vernier Calipers with a resolution of 0.01 mm. Statistical Analysis: Correlation between mesiodistal and buccolingual tooth sizes amongst siblings was calculated using Pearson's correlation coefficient. Results: A statistically significant association was found between Mesiodistal Widths of Permanent Maxillary Right and Left Second Molars and between Maxillary Right and Left First Premolars amongst sibling pairs. A statistically significant association was also found between Buccolingual Widths of Mandibular Right and Left First Premolars amongst sibling pairs. This statistically significant correlation found amongst siblings establishes a genetic control over sexual dimorphism in these teeth. Conclusion: The genetic basis of sexual dimorphism in human dentition was ascertained as a significant correlation was found between mesio-distal and bucco-lingual widths of premolars between sibling pairs. PMID:24783145

Sharma, Sonali; Dinkar, Ajit D; Bedi, Sumit

2014-03-01

169

Aims: This study aims to establish biological reference interval for novel platelet parameters. Settings and Design: A total of 945 healthy individuals, age ranges from 18 to 64 years (881 males and 64 females) coming for voluntary blood donation from June to August 2012 (3 months) were enrolled after exclusion of rejection criteria. Materials and Methods: The samples were assayed by running in complete blood count + reticulocyte mode on the Sysmex XE-2100 hematology analyzer and the reference interval for the population was calculated using Clinical and Laboratory Standards Institute guidelines. Statistical analysis used: Tests were performed using SPSS (Statistical Product and Service Solutions , developed by IBM corporation), version 13. Student t test and pearsons correlation analysis were also used. Results: The normal range for various parameters was platelet count: 150-520 × 10 3 /cu mm, immature platelet fraction (IPF): 0.3-8.7%, platelet distribution width (PDW): 8.3-25.0 fL, mean platelet volume (MPV): 8.6-15.5 fL, plateletcrit (PCT): 0.15-0.62%, high immature platelet fraction (H-IPF): 0.1-2.7%, platelet large cell ratio (P-LCR): 11.9-66.9% and platelet-X (PLT-X) (ch): 11.0-22.0. Negative correlation was observed between platelet count (r = -0.468 to r = -0.531; P < 0.001) and PCT (r = -0.080 to r = -0.235; P < 0.05 to P < 0.001) with IPF, PDW, MPV, H-IPF, P-LCR, and platelet-X. IPF/H-IPF showed a positive correlation among them and also with PDW, MPV, P-LCR, platelet-X (r = +0.662 to r = +0.925; P < 0.001). Conclusions: These novel platelet parameters offer newer avenues in research and clinical use. Establishing biological reference interval for different platelet parameters would help determine true high and low values and help guide treatment decisions. PMID:24943755

Sachdev, Ritesh; Tiwari, Aseem K; Goel, Shalini; Raina, Vimarsh; Sethi, Monisha

2014-01-01

170

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

171

This study explores the effects of different correlation types (covariance and correlation matrix, obtained from Pearson, Goodman, and Tetrachoric) on goodness-of-fit indices in first order and second order factor analysis. The data included Math and Science subsets in Student Selection and Placement Examination for Secondary Education test administered in 2001 with the participation of 553108 students. A first-order and second-order

Halil Yurdugül

2007-01-01

172

NASA Astrophysics Data System (ADS)

Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques.

Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.

2014-04-01

173

Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640

Burnett, T L; McDonald, S A; Gholinia, A; Geurts, R; Janus, M; Slater, T; Haigh, S J; Ornek, C; Almuaili, F; Engelberg, D L; Thompson, G E; Withers, P J

2014-01-01

174

Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques.

Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.

2014-01-01

175

Smoothed Regression Estimates with Pearson Noise.

National Technical Information Service (NTIS)

Li and Hwang (1984) examined estimates for a regression problem which are a compromise between the naive, raw data estimate and a nonparametric estimate. They developed such compromise, or smoothed, estimates assuming Gaussian noise. This report, develops...

R. W. Johnson

1988-01-01

176

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

177

A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.

Sinclair, Michael B. (Albuquerque, NM) [Albuquerque, NM; Pfeifer, Kent B. (Los Lunas, NM) [Los Lunas, NM; Flemming, Jeb H. (Albuquerque, NM) [Albuquerque, NM; Jones, Gary D. (Tijeras, NM) [Tijeras, NM; Tigges, Chris P. (Albuquerque, NM) [Albuquerque, NM

2010-04-13

178

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.

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

2014-01-01

179

NASA Astrophysics Data System (ADS)

In the first part of these lecture notes we introduce the phenomenological equations for describing the heat and charge transport in thermoelectric samples. We discuss the solution obtained for various boundary conditions that are appropriate for the homogeneous and inhomogeneous thermoelectrics. In the second part we develop the formalism for a linear-response many-body description of the transport properties of correlated electrons. By properly determining the local heat-current operator we show that the Jonson-Mahan theorem applies to the Hamiltonians that are commonly used for the intermetallic compounds with Cerium, Europium and Ytterbium ions, so the various thermal-transport coefficient integrands are related by powers of frequency. We illustrate how to use this formalism by calculating the thermoelectric properties of the periodic Anderson model and, then, show that these results explain the experimental data on heavy fermions and valence fluctuators. Finally, we calculate the thermoelectric properties of the Falicov-Kimball model and use the results to explain the anomalous features of the intermetallic compounds in which one observes the valence-change transition.

Zlati?, V.

2008-05-01

180

Correlation of Ranges of Correlated Deviates.

National Technical Information Service (NTIS)

The correlation between ranges of correlated normal deviates is assessed, exactly for ranges of 2 and 3, approximately for ranges of 4 or more, with results modifying those of Hartley (1950). The approximation is asymptotic in the correlation between the ...

T. E. Kurtz R. F. Link J. W. Tukey D. L. Wallace

1966-01-01

181

Type II Robustness of H0: Rho=0 for Non-Normal Distributions

ERIC Educational Resources Information Center

Is the t test statistic for the Pearson Product Moment Correlation Coefficient robust to errors of the second kind? This investigation indirectly measured the effects of power through a type 2 error rate robustness study. The results were revealing. [The dissertation citations contained here are published with the permission of ProQuest LLC.…

Wren, Stephanie D.

2010-01-01

182

This study examines strategic process and export entry choice of small and medium manufacturing firms in Nigeria. The data was collected from a survey of 72 small and medium-sized manufacturers in Nigeria. Data were analyzed using descriptive statistics, t-test, and Pearson's product moment correlation analysis. Results show that firms' strategic choice to enter the export market was associated with entrepreneurial

John O. Okpara; Nicholas J. Koumbiadis

183

Objective: To compare different statistical methods for assessing the relative validity of a self-administered, 150-item, semi-quantitative food-frequency questionnaire (FFQ) with 4-day weighed diet records (WR). Design: Subjects completed the Scottish Collaborative Group FFQ and carried out a 4- day WR. Relative agreement between the FFQ and WR for energy-adjusted nutrient intakes was assessed by Pearson and Spearman rank correlation coefficients,

LF Masson; G MCNeill; JO Tomany; JA Simpson; HS Peace; L Wei; DA Grubb; C Bolton-Smith

2003-01-01

184

Dyslipidemia After Kidney Transplantation and Correlation With Cyclosporine Level

Background Dyslipidemia after kidney transplantation is a frequent finding and is multifactorial. Immunosuppressive agents such as cyclosporine (CsA) can cause hypercholesterolemia. Objectives As there were few reports with conflicting evidence on whether CsA related dyslipidemia is dose related and that CsA monitoring assays (trough level, C0, or two hour post dose level, C2) is a better predictor for dyslipidemia development; hence, the current study, in a large sample size, was designed to answer these questions. 3. Patients and Methods In the current retrospective cross sectional study, 1391 kidney transplant recipients were enrolled. All patients received CsA plus mycophenolatemofetile or azathioprine and prednisolone. Serum creatinine, CsA blood levels and lipid profile were measured after 12-14 h fasting. Mann-Whitney and Kruskal-Wallis, Pearson`s test and logistic regression were used for data analyses. Results Mean age of 1391studied population was 38.7 ± 15 years old. Hypercholesterolemia and hypertriglyceridemia were observed in 58.9% and 86.6%, respectively and they were more significantly detected in cadaveric kidney transplantation. Dyslipidemia had weak correlation with age of recipient, serum creatinine, C0 and C2 levels of CsA. At logistic regression, serum creatinine was the only risk factor for hypercholesterolemia development after kidney transplantation (OR = 1.6, CI 95%: 1.4 -1.8). Conclusions Dyslipidemia is a common finding after kidney transplantation and has no correlation with CsA level. According to conflicting data on the precise effect of different factors in inducing dyslipidemia, prospective large sample size studies should consider better control of dyslipidemia.

Hosseini, Mahboobeh-Sadat; Rostami, Zohreh; Einollahi, Behzad

2013-01-01

185

Graph theoretical analysis of brain networks based on resting-state functional MRI (R-fMRI) has attracted a great deal of attention in recent years. These analyses often involve the selection of correlation metrics and specific preprocessing steps. However, the influence of these factors on the topological properties of functional brain networks has not been systematically examined. Here, we investigated the influences of correlation metric choice (Pearson's correlation versus partial correlation), global signal presence (regressed or not) and frequency band selection [slow-5 (0.01-0.027 Hz) versus slow-4 (0.027-0.073 Hz)] on the topological properties of both binary and weighted brain networks derived from them, and we employed test-retest (TRT) analyses for further guidance on how to choose the "best" network modeling strategy from the reliability perspective. Our results show significant differences in global network metrics associated with both correlation metrics and global signals. Analysis of nodal degree revealed differing hub distributions for brain networks derived from Pearson's correlation versus partial correlation. TRT analysis revealed that the reliability of both global and local topological properties are modulated by correlation metrics and the global signal, with the highest reliability observed for Pearson's-correlation-based brain networks without global signal removal (WOGR-PEAR). The nodal reliability exhibited a spatially heterogeneous distribution wherein regions in association and limbic/paralimbic cortices showed moderate TRT reliability in Pearson's-correlation-based brain networks. Moreover, we found that there were significant frequency-related differences in topological properties of WOGR-PEAR networks, and brain networks derived in the 0.027-0.073 Hz band exhibited greater reliability than those in the 0.01-0.027 Hz band. Taken together, our results provide direct evidence regarding the influences of correlation metrics and specific preprocessing choices on both the global and nodal topological properties of functional brain networks. This study also has important implications for how to choose reliable analytical schemes in brain network studies. PMID:22412922

Liang, Xia; Wang, Jinhui; Yan, Chaogan; Shu, Ni; Xu, Ke; Gong, Gaolang; He, Yong

2012-01-01

186

Correlating correlation functions of primordial perturbations

NASA Astrophysics Data System (ADS)

We explore the correlations between correlation functions of the primordial curvature perturbation produced during inflation. We find that for general single field inflation, other than the source terms which depend on the model details, higher order correlation functions are characterized by the power spectrum, its spectral index and running. The correlation between the bispectrum and power spectrum is presented as an explicit example of our systematic approach.

Gong, Jinn-Ouk; Schalm, Koenraad; Shiu, Gary

2014-03-01

187

YKL-40 in Asthma and its Correlation with Different Clinical Parameters.

It has been suggested that elevated serum level of YKL-40 could be a marker for asthma and its severity. Along with few published studies, we investigated its correlation with asthma and its severity as well as spirometric indices.114 patients with asthma and 114 healthy controls underwent the assessment of serum level of YKL-40 (by ELISA) and spirometric indices. Pearson's coefficient determined the correlation between the variables and multivariate linear regression analysis was used for adjusting the effect of different probable confounding factors.Serum levels of YKL-40 were significantly higher in the asthmatic patients compared to those in healthy people (p<0.001). We also found a significant correlation between YKL-40 serum level and spirometric indices even after adjusting the effects of other variables.We report for the first time in an Iranian population that YKL-40 may be a good diagnostic marker of asthma in serum. PMID:24659163

Saba, Mohammadali; Sharif, Mohammad Reza; Akbari, Hossein; Nikoueinejad, Hassan; Ramazani Jolfaii, Maryam

2014-08-01

188

Correlations between ten-channel EEGs obtained from thirteen healthy adult participants were investigated. Signals were obtained in two behavioral states: eyes open no task and eyes closed no task. Four time domain measures were compared: Pearson product moment correlation, Spearman rank order correlation, Kendall rank order correlation and mutual information. The psychophysiological utility of each measure was assessed by determining its ability to discriminate between conditions. The sensitivity to epoch length was assessed by repeating calculations with 1, 2, 3, …, 8 s epochs. The robustness to noise was assessed by performing calculations with noise corrupted versions of the original signals (SNRs of 0, 5 and 10 dB). Three results were obtained in these calculations. First, mutual information effectively discriminated between states with less data. Pearson, Spearman and Kendall failed to discriminate between states with a 1 s epoch, while a statistically significant separation was obtained with mutual information. Second, at all epoch durations tested, the measure of between-state discrimination was greater for mutual information. Third, discrimination based on mutual information was more robust to noise. The limitations of this study are discussed. Further comparisons should be made with frequency domain measures, with measures constructed with embedded data and with the maximal information coefficient. PMID:24465281

Bonita, J D; Ambolode, L C C; Rosenberg, B M; Cellucci, C J; Watanabe, T A A; Rapp, P E; Albano, A M

2014-02-01

189

Geometric correlations and multifractals.

National Technical Information Service (NTIS)

There are many situations where the usual statistical methods are not adequate to characterize correlations in the system. To characterize such situations we introduce mutual correlation dimensions which describe geometric correlations in the system. Thes...

R. E. Amritkar

1991-01-01

190

The t-test Tutorial: Comparing Cultures

NSDL National Science Digital Library

This tutorial, created by Dale Berger of Claremont Graduate University, takes the learner step-by-step in applying descriptive and inferential statistics using a real world situation. The site focuses on the cultural differences in child rearing in the countries of Belize and Samoa. Overall, this is a great site for applied statistical theories.

Berger, Dale

2008-12-22

191

This cross-sectional study investigated the correlates of body mass index (BMI) and risk factors for overweight among 91 children with motor delay (MD) aged 9-73 months. Anthropometric measurements and questionnaires regarding multiple risk factors were obtained. Simple correlations between BMI percentile classifications and potential predictors were examined using Spearman's rank/Pearson's correlations and ?2 analysis. Multiple predictors of overweight were analyzed using logistic regression. BMI was correlated positively with higher caloric intake (rs = .21, p < .05) and negatively with passive activity (rs = ?.21, p < .05). When multiple predictors were considered, more severe dysphagia (odds ratio [OR], 2.81, p = .027, 95% confidence interval [CI], 1.13-7.03) and antiepileptic drug use (OR, 19.11, p = .008, 95% CI, 2.14-170.81) had significant partial effects on overweight status. Agencies supporting early development should consider caregiver education regarding the potential implication of feeding style and medication on BMI. PMID:24762387

Hwang, Ai-Wen; Wu, I-Chin; Chen, Chiao-Nan; Cheng, Hsin-Yi Kathy; Chen, Chia-Ling

2014-04-01

192

Object enhanced optical correlation

NASA Technical Reports Server (NTRS)

A major drawback of optical correlator systems is the poor quality of correlation signals. Background noise is one of the many sources of false correlation peaks. However, by reconstructing an input scene with the object's amplitude function, an object-enhanced scene - used as input to the optical correlators - (with respect to background) can be obtained. Thus, the optical correlation of this enhanced image improves the signal-to-noise ratio in the correlation image. Furthermore, construction of a filter plane mask that permits simultaneous scene enhancement and cross-correlation operations is described. Experimental results demonstrate the practicality of this approach.

Scholl, Marija S.; Shumate, Michael S.; Udomkesmalee, Suraphol

1991-01-01

193

A New Validity Measure for a Correlation-Based Fuzzy C-means Clustering Algorithm

One of the major challenges in unsupervised clustering is the lack of consistent means for assessing the quality of clusters. In this paper, we evaluate several validity measures in fuzzy clustering and develop a new measure for a fuzzy c-means algorithm which uses a Pearson correlation in its distance metrics. The measure is designed with within-cluster sum of square, and makes use of fuzzy memberships. In comparing to the existing fuzzy partition coefficient and a fuzzy validity index, this new measure performs consistently across six microarray datasets. The newly developed measure could be used to assess the validity of fuzzy clusters produced by a correlation-based fuzzy c-means clustering algorithm.

Zhang, Mingrui; Zhang, Wei; Sicotte, Hugues; Yang, Ping

2009-01-01

194

A new validity measure for a correlation-based fuzzy c-means clustering algorithm.

One of the major challenges in unsupervised clustering is the lack of consistent means for assessing the quality of clusters. In this paper, we evaluate several validity measures in fuzzy clustering and develop a new measure for a fuzzy c-means algorithm which uses a Pearson correlation in its distance metrics. The measure is designed with within-cluster sum of square, and makes use of fuzzy memberships. In comparing to the existing fuzzy partition coefficient and a fuzzy validity index, this new measure performs consistently across six microarray datasets. The newly developed measure could be used to assess the validity of fuzzy clusters produced by a correlation-based fuzzy c-means clustering algorithm. PMID:19963601

Zhang, Mingrui; Zhang, Wei; Sicotte, Hugues; Yang, Ping

2009-01-01

195

Quantum correlations from classically correlated states

NASA Astrophysics Data System (ADS)

Consider a bipartite quantum system with at least one of its two components being itself a composite system. By tracing over part of one (or both) of these two subsystems it is possible to obtain a reduced (separable) state that exhibits quantum correlations even if the original state of the full system is endowed only with classical correlations. This effect, first pointed out by Li and Luo in (2008), is of considerable interest because there is a growing body of evidence suggesting that quantum correlations in non-entangled, mixed states may constitute a useful resource to implement non trivial information related tasks. Here we conduct a systematic exploration of the aforementioned effect for particular families of states of quantum systems of low dimensionality (three qubits states). In order to assess the non-classicality of the correlations of the reduced states we use an indicator of quantum correlations based upon the state disturbances generated by the measurement of local observables. We show, for a three-qubit system, that there exists a relationship between the classical mutual information of the original classically correlated states and the maximum quantum correlation exhibited by the reduced states.

Bellomo, G.; Majtey, A. P.; Plastino, A. R.; Plastino, A.

2014-07-01

196

Miniaturized optical correlator

NASA Technical Reports Server (NTRS)

A robust optical correlator that is a miniaturized version of the classic Vander-Lugt correlator is developed. The correlator consists of a simple diode laser for illumination and a CMOS photodetector to detect the correlation peak. A set of roof prisms is configured to fold the light path into a compact design. A holographic plate is used for storing the matched filter. This correlator is particularly applicable to docking autonomous vehicles near a predesignated landing mark. This miniature optical correlator is described in terms of its functional performance.

Scholl, M. S.; Shumate, M. S.; Hartman, R. L.; Sloan, J. A.; Small, D.

1990-01-01

197

Codes with special correlation.

NASA Technical Reports Server (NTRS)

Uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets

Baumert, L. D.

1964-01-01

198

Abstract, A new, fast, statistically robust, exhaustive, transla-tional image-matching technique is presented: fast robust corre-lation. Existing methods are either slow or non-robust, or rely on optimization. Fast robust correlation works by expressing a robust matching surface as a series of correlations. Speed is obtained by computing correlations in the frequency domain. Computational cost is analyzed and the method is shown

Alistair J. Fitch; Alexander Kadyrov; William J. Christmas; Josef Kittler

2005-01-01

199

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

200

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

201

ERIC Educational Resources Information Center

Interpretation of correlation is often based on rules of thumb in which some boundary values are given to help decide whether correlation is non-important, weak, strong or very strong. This article shows that such rules of thumb may do more harm than good, and instead of supporting interpretation of correlation--which is their aim--they teach a…

Kozak, Marcin

2009-01-01

202

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

203

Background There are two major hemodynamic stresses imposed at the blood arterial wall interface by flowing blood: the wall shear stress (WSS) acting tangentially to the wall, and the wall pressure (WP) acting normally to the wall. The role of flow wall shear stress in atherosclerosis progression has been under intensive investigation, while the impact of blood pressure on plaque progression has been under-studied. Method The correlations of wall thickness (WT) with wall pressure (WP, blood pressure on the lumen wall) and spatial wall pressure gradient (WPG) in a human atherosclerotic right coronary artery were studied. The pulsatile blood flow was simulated using a three dimensional mathematical model. The blood was treated as an incompressible viscous non-Newtonian fluid. The geometry of the artery was re-constructed using an in vivo intravascular ultrasound (IVUS) 44-slice dataset obtained from a patient with consent obtained. The WT, the WP and the WPG were averaged on each slice, respectively, and Pearson correlation analysis was performed on slice averaged base. Each slice was then divided into 8 segments and averaged vessel WT, WP and WPG were collected from all 352 segments for correlation analysis. Each slice was also divided into 2 segments (inner semi-wall of bend and outer semi-wall of bend) and the correlation analysis was performed on the 88 segments. Results Under mean pressure, the Pearson coefficient for correlation between WT and WP was r?=?? 0.52 (p?Pearson coefficient for correlation between WT and WPG was r?=?0.30 (p?=?0.004) by 2-segment analysis and r?=?0.45 (p?=?0.002) by slice averaged analysis, respectively. The r-values corresponding to systole and diastole pressure conditions were similar. Conclusions Results from this representative case report indicated that plaque wall thickness correlated negatively with wall pressure (r?=??0.81 by slice) and positively with wall pressure gradient (r?=?0.45). The slice averaged WT has a strong linear relationship with the slice averaged WP. Large-scale patient studies are needed to further confirm our findings.

2012-01-01

204

Direct measure of local region functional connectivity by multivariate correlation technique.

In order to identify the local areas whose activity are most similar with region of interest (ROI), we usually compute the correlation of fMRI data for the brain functional connectivity. The fMRI data is usually noisy, extraction of functional connectivity with the voxel by voxel based method such as Pearson correlation analysis is not robust. Many people smooth the fMRI data before compute the correlation coefficient, which only makes the effect worse, because some useful original information is lost during the smoothing. Here, we analyzed this issue in details and improved the data processing flow to make the result better. Furthermore, a new criterion RV correlation coefficient was introduced in this article to measure the correlation between two local brain regions; this multivariate correlation technique applied the spatiotemporal information within the local regions to measure the similarity of the activity in different brain regions. We compared four different strategies mentioned above to detect the functional connectivity on the simulated and real fMRI data, and the results demonstrated that the RV-coefficient method obtained the best performance. PMID:18003187

Zhang, Hui; Tian, Jie; Zhen, Zonglei

2007-01-01

205

Correlation between serum gastrin and cellular proliferation in Barrett's esophagus.

Background: Patients with Barrett's esophagus (BE) are commonly treated with proton-pump inhibitors (PPIs) to minimize the exposure of esophageal mucosa to stomach acid. However, the use of these medications can lead to significant hypergastrinemia in a subset of patients, which is concerning due to the known tumorigenic and proliferative effects of gastrin. The present pilot study aims to investigate a potential correlation between serum gastrin and cellular proliferation in BE.Methods: We performed a cross-sectional analysis of patients with nondysplastic BE on PPI therapy. Fasting serum gastrin was measured on the same day as esophageal biopsies were obtained. These biopsies were then stained with Ki-67 nuclear antibody. Pearson's correlation coefficient was calculated to assess the relationship between Ki-67 index and ln(gastrin).Results: A total of 10 patients were included in the study. The mean age was 62.6 (±8.4) years and 5 patients were male. The median serum gastrin level was 45.2 pM (interquartile range [IQR] 33-113) and the median Ki-67 index was 49.6% (IQR 23-64). We found a statistically significant positive correlation between Ki-67 index and ln(gastrin) (r?=?0.64; p?=?0.05).Conclusions: In nondysplastic BE patients on PPI therapy, serum gastrin levels were significantly correlated with cellular proliferation. These pilot data lend support to a potential causal effect of gastrin on neoplastic progression in BE. Longitudinal studies of patients with BE are needed to determine whether hypergastrinemia is a risk factor for the development of dysplasia and adenocarcinoma or could be used as a biomarker for disease progression. PMID:21694810

Green, Daniel A; Mlynarczyk, Carrie M; Vaccaro, Benjamin J; Capiak, Kristina M; Quante, Michael; Lightdale, Charles J; Abrams, Julian A

2011-03-01

206

The Correlation between Echocardiographic Findings and QT Interval in Cirrhotic Patients

Background: Although many electrocardiographic abnormalities have been reported previously, prolonged QTC interval represented as the most important ECG finding in patients with liver cirrhosis. Echocardiography can detect structural cardiac abnormalities in cirrhotic patients. Objectives: The present study aimed to determine the correlation between QTC prolongation and echocardiographic findings in end stage liver cirrhosis. Methods: The present study was conducted on 100 patients selected through convenient sampling. We recruited 80 cirrhotic patients with CHILD score > B or MELD score > 15 from the transplantation ward of Nemazee educational hospital. A complete echocardiographic study, including chamber quantification, a complete flow Doppler, and tissue Doppler analysis, was performed for each patient using a GE vivid 3 system equipped with Tissue Doppler Imaging (TDI). Then, twelve-lead ECG was carried out and QTc interval was calculated in all patients. The data were analyzed using the SPSS statistical software (v. 13) and Pearson’s correlation coefficient. P value < 0.05 was considered statistically significant. Results: The patients’ age ranged from 20 to 60 years old and 62.5% of them were male. According to the results, the only parameter which was significantly associated with prolonged QTc interval was Left Ventricular End Diastolic Dimension (LVEDD). Additionally, a linear direct relationship was found between corrected QT interval and LVEDD (r = 0.41, P < 0.001). Conclusions: The current study showed a positive correlation between QTC prolongation as an electerocardiographic finding and LVEDD in echocardiography of the cirrhotic patients. This may indicate a direct relationship between the electrophysiological problems and the severity of volume overload in cirrhotic patients.

Moaref, Alireza; Zamirian, Mahmood; Yazdani, Maryam; Salehi, Oveis; Sayadi, Mehrab; Aghasadeghi, Kamran

2014-01-01

207

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.

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

2012-01-01

208

Purpose: Luminal diameters measured in vivo by calibrated-catheter angiography and by intravascular ultrasound were correlated with those obtained from pressure-fixed histologic cross-sections to determine the accuracy of both methods. Methods: Angiographic and endosonographic diameter measurements were performed in the center of stents placed in the iliac arteries of 10 miniature pigs and were compared with luminal and stent diameters in postmortem, pressure-fixed, histologic cross-sections from identical locations. Results: Compared with histologic diameters, magnification-corrected angiographic measurements still magnified vascular luminal diameters by 0.7 {+-} 0.71 mm (r= 0.41, Pearson; p < 0.003, Wilcoxon, matched pairs), whereas intravascular ultrasound measurements proved to be almost identical to the histologic lumina (r= 0.95, Pearson; p> 0.5, Wilcoxon, matched pairs). Similarly, stent diameters correlated well between endosonographic and histologic measurements (r= 0.91; p= 0.002), and less well between angiographic and histologic diameters (r= 0.62; p= 0.002). Conclusion: Since calibrated angiography still overestimates vascular lumina, endosonography is the preferred technique for accurate in vivo measurements.

Froelich, Jens J.; Hoppe, Martin; Nahrstedt, Christoph [Medizinisches Zentrum fuer Radiologie, Abteilung fuer Strahlendiagnostik, Klinikum der Philipps-Universitaet, Baldingerstrasse, D-35043 Marburg (Germany); Barth, Klemens H. [Division of Vascular and Interventional Radiology, Georgetown University Hospital, 3800 Reservoir Road, N.W., Washington, DC 20007 (United States); Wagner, H. Joachim; Klose, Klaus J. [Medizinisches Zentrum fuer Radiologie, Abteilung fuer Strahlendiagnostik, Klinikum der Philipps-Universitaet, Baldingerstrasse, D-35043 Marburg (Germany)

1997-11-15

209

Correlation in photodetachment

Electron correlation plays a major role in all aspects of the photodetachment of an electron from a negative ion. Photodetachment measurements are well suited to investigate the relatively short range forces associated with correlation due to the absence of the long range Coulomb interaction. Measurements of electron affinities, asymmetry parameters and cross sections are described to illustrate the influence of correlation on photodetachment. 25 refs., 4 figs.

Pegg, D.J. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

210

NASA Astrophysics Data System (ADS)

Particle correlations are extensively studied to obtain information about the dynamics of hadron production. Prom 1989 to 2000 the four LEP collaborations recorded more than 16 million hadronic Z0 decays and several thousand W+W- events. In Z0 decays, two-particle correlations were analysed in detail to study Bose-Einstein and Fermi-Dirac correlations for various particle species. In fully-hadronic W+W- decays, particle correlations were used to study whether the two W bosons decay independently. A review of selected results is presented.

Kress, T. H.

2002-07-01

211

High YKL-40 Serum Concentration Is Correlated with Prognosis of Chinese Patients with Breast Cancer

This study aimed to investigate the association between serum YKL-40 and prognosis of breast cancer in a Chinese population. Expression of YKL-40 of 120 Chinese patients with breast cancer and 30 controls (benign breast lesions) was measured in tumor tissue by immunohistochemistry and in serum by ELISA. Differences in YKL-40 positivity grouped by specific patients’ characteristics were compared using Pearson Chi-square test for rates of intratumoral staining, one-way ANOVA with a Bonferroni post-hoc comparison, or two-sample t-test for mean YKL-40 serum concentrations. Factors associated with overall survival were identified by univariate and multivariate cox-regression analyses. YKL-40 was elevated in approximately 75% of Chinese patients with breast cancer. A significantly higher percentage of patients with YKL-40 positive tumors had larger tumor size, higher TNM stage, and/or lymph node metastasis. Significantly higher mean YKL-40 serum concentrations were observed in patient subgroups with invasive lobular carcinoma (P<0.0167), higher TNM stage (P<0.001), and positive lymph node metastasis (P<0.001). The estimated mean survival time of patients with YKL-40 positive tumors was significantly shorter than for patients with YKL-40 negative tumors (55.13 months vs 65.78 months, P?=?0.017). Multivariable Cox-regression analysis identified a significant association of overall survival time with YKL-40 serum concentration. Patients with YKL-40 positive tumors had significantly shorter disease free survival times than those with YKL-40 negative tumors. We propose that the potential utility of YKL-40 intratumoral staining or serum concentration as a biomarker for breast cancer is greatest within 5 years of diagnosis.

Wang, Dong; Zhai, Bo; Hu, Fengli; Liu, Chang; Zhao, Jinpeng; Xu, Jun

2012-01-01

212

Objective: The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. Methods: The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson’s correlation coefficient. Results: Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, p<0.033) and eDE (R=0.77, p<0.008) were observed. Conclusion: Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and optimisation studies with a degree of confidence that they reflect the clinical image quality in chest CR images acquired without an antiscatter grid. Advances in knowledge: A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography.

Wood, T J; Beavis, A W; Saunderson, J R

2013-01-01

213

\\u000a This chapter reviews two issues related to responses correlated with loudness. First, the physiological effects of loud sounds\\u000a are examined. Then, specific indirect measures, both perceptual and physiological that correlate with loudness growth, are\\u000a summarized.

Michael J. Epstein

214

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.

2014-01-01

215

Background The synthesis of information across microarray studies has been performed by combining statistical results of individual studies (as in a mosaic), or by combining data from multiple studies into a large pool to be analyzed as a single data set (as in a melting pot of data). Specific issues relating to data heterogeneity across microarray studies, such as differences within and between labs or differences among experimental conditions, could lead to equivocal results in a melting pot approach. Results We applied statistical theory to determine the specific effect of different means and heteroskedasticity across 19 groups of microarray data on the sign and magnitude of gene-to-gene Pearson correlation coefficients obtained from the pool of 19 groups. We quantified the biases of the pooled coefficients and compared them to the biases of correlations estimated by an effect-size model. Mean differences across the 19 groups were the main factor determining the magnitude and sign of the pooled coefficients, which showed largest values of bias as they approached ±1. Only heteroskedasticity across the pool of 19 groups resulted in less efficient estimations of correlations than did a classical meta-analysis approach of combining correlation coefficients. These results were corroborated by simulation studies involving either mean differences or heteroskedasticity across a pool of N?>?2 groups. Conclusions The combination of statistical results is best suited for synthesizing the correlation between expression profiles of a gene pair across several microarray studies.

2013-01-01

216

NASA Astrophysics Data System (ADS)

Correlators between event planes of different harmonics in relativistic heavy-ion collisions have the potential to provide crucial information on the initial state of the matter formed in these collisions. We present a new procedure for analyzing such correlators, which is less demanding in terms of detector acceptance than the one used recently by the ATLAS Collaboration to measure various two-plane and three-plane correlators in Pb-Pb collisions at the Large Hadron Collider (LHC). It can also be used unambiguously for quantitative comparison between theory and data. We use this procedure to carry out realistic simulations within a multiphase transport (AMPT) model. Our theoretical results are in excellent agreement with the ATLAS data, in contrast with previous hydrodynamic calculations which only achieved qualitative agreement. We present predictions for new correlators, in particular four-plane correlators, which can easily be analyzed with our new method.

Bhalerao, Rajeev S.; Ollitrault, Jean-Yves; Pal, Subrata

2013-08-01

217

Correlations in nuclear matter

NASA Astrophysics Data System (ADS)

We analyze the nuclear matter correlation properties in terms of the pair correlation function. To this aim we systematically compare the results for the variational method in the lowest-order constrained variational (LOCV) approximation and for the Bruekner-Hartree-Fock (BHF) scheme. A formal link between the Jastrow correlation factor of LOCV and the defect function (DF) of BHF is established and it is shown under which conditions and approximations the two approaches are equivalent. From the numerical comparison it turns out that the two correlation functions are quite close, which indicates in particular that the DF is approximately local and momentum independent. The equations of state (EOS) of nuclear matter in the two approaches are also compared. It is found that once the three-body forces (TBF) are introduced, the two EOS are fairly close, while the agreement between the correlation functions holds with or without TBF.

Baldo, M.; Moshfegh, H. R.

2012-08-01

218

Explorations in statistics: correlation

NSDL National Science Digital Library

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This sixth installment of Explorations in Statistics explores correlation, a familiar technique that estimates the magnitude of a straight-line relationship between two variables. Correlation is meaningful only when the two variables are true random variables: for example, if we restrict in some way the variability of one variable, then the magnitude of the correlation will decrease. Correlation cannot help us decide if changes in one variable result in changes in the second variable, if changes in the second variable result in changes in the first variable, or if changes in a third variable result in concurrent changes in the first two variables. Correlation can help provide us with evidence that study of the nature of the relationship between x and y may be warranted in an actual experiment in which one of them is controlled.

PhD Douglas Curran-Everett (National Jewish Medical and Research Center Div. Biostatistics, Depts. Prev. Med./Biometrics, Physiology/Biophys)

2010-10-01

219

Correlation reflectometry at TEXTOR

NASA Astrophysics Data System (ADS)

In high temperature fusion plasmas the transport of energy and particles is commonly believed to be driven by turbulence. Turbulence quantities as correlation length and decorrelation time are important for the confinement properties of a plasma. Besides other diagnostics, correlation reflectometry has proven to be a suitable tool for the measurement of turbulence properties. At the medium sized Toroidal EXperiment for Technical Oriented Research (TEXTOR) the existing correlation reflectometry has been recently upgraded. A new reflectometer based on a microwave synthesizer has been developed and installed for the investigation of turbulence properties in a fusion plasma. Together with the existing reflectometer the measurement of radial correlation length and decorrelation time becomes available. Both reflectometers are computer controlled and allow to program individual frequency sequences and the duration of each frequency step. With the existing poloidal antenna array at ?=0° and on top of the vacuum vessel, the system allows the measurement of radial correlation and poloidal correlations at the same time. First experiments have been performed and the results on the radial correlation length of density fluctuations in a fusion plasma are presented.

Krämer-Flecken, A.; Soldatov, S.; Vowinkel, B.; Müller, P.

2010-11-01

220

Spatial and time correlation of thermometers and pluviometers in a weather network database

NASA Astrophysics Data System (ADS)

A basic issue that arises when analysing data bases from weather networks is the correlation system that characterizes the set of weather stations. Some statistical models being used for simulating temperature and precipitation or estimating missing data often exploit the Pearson's correlation coefficient, whereby a selection of predictors is carried out. In this paper, a specific analysis was made to understand the relationship between the distances (between the stations) and the correlation structure (of the network) and to assess the evolution of the stations ranking over the time from the network establishment, given that they were ranked on the basis of their correlation coefficient values with a target station. This study was first carried out over the whole of the Veneto region in Northeast Italy, and subsequently, it was repeated, subdividing the area into three main climatic zones: mountain, plain and coast. The variables that are involved in this study are the following: daily precipitation and daily maximum, mean and minimum temperature. Generally, the correlation coefficients of the database of precipitation are, on average, inversely proportional to the mean distances from the target station. Considering that the same behaviour was not detected on analysing the temperature database, the main results of this work can be summarized as follows: (1) the most correlated stations of precipitation are generally closer to a target station than the most correlated stations of temperature (entire area); (2) starting from 5.5 years after the network was established, the temperature variable is characterized by a high stability (over time) of the correlation rankings, up to a wide radius from the target station; (3) this trend is not so clear in precipitation data. However, when taking into account the first result, (4) generally, the most correlated stations are placed within the radius of stability, more frequently so for precipitation than for temperature.

Tardivo, Gianmarco

2014-04-01

221

We compared the powers of the likelihood ratio test (LRT) and the Pearson correlation test (CT) from empirical Bayes estimates (EBEs) for various designs and shrinkages in the context of nonlinear mixed-effect modeling. Clinical trial simulation was performed with a simple pharmacokinetic model with various weight (WT) effects on volume (V). Data sets were analyzed with NONMEM 7.2 using first-order conditional estimation with interaction and stochastic approximation expectation maximization algorithms. The powers of LRT and CT in detecting the link between individual WT and V or clearance were computed to explore hidden or induced correlations, respectively. Although the different designs and variabilities could be related to the large shrinkage of the EBEs, type 1 errors and powers were similar in LRT and CT in all cases. Power was mostly influenced by covariate effect size and, to a lesser extent, by the informativeness of the design. Further studies with more models are needed.

Combes, F P; Retout, S; Frey, N; Mentre, F

2014-01-01

222

We compared the powers of the likelihood ratio test (LRT) and the Pearson correlation test (CT) from empirical Bayes estimates (EBEs) for various designs and shrinkages in the context of nonlinear mixed-effect modeling. Clinical trial simulation was performed with a simple pharmacokinetic model with various weight (WT) effects on volume (V). Data sets were analyzed with NONMEM 7.2 using first-order conditional estimation with interaction and stochastic approximation expectation maximization algorithms. The powers of LRT and CT in detecting the link between individual WT and V or clearance were computed to explore hidden or induced correlations, respectively. Although the different designs and variabilities could be related to the large shrinkage of the EBEs, type 1 errors and powers were similar in LRT and CT in all cases. Power was mostly influenced by covariate effect size and, to a lesser extent, by the informativeness of the design. Further studies with more models are needed. PMID:24717242

Combes, F P; Retout, S; Frey, N; Mentré, F

2014-01-01

223

Examining Correlates of Diversity.

ERIC Educational Resources Information Center

Statistical methods are presented for studying "correlates of diversity," defined as characteristics of educational organizations that predict dispersion on the dependent variable. Strategies based on exact distribution theory and asymptotic normal approximation are considered. (TJH)

Raudenbush, Stephen W.; Bryk, Anthony S.

1987-01-01

224

Fluorescence Correlation Spectroscopy

NSDL National Science Digital Library

This paper, which was previously published as part of an online biophysics textbook, provides detailed information about concepts related to fluorescence correlation spectroscopy. Sections of the document include writing on experimental realization, theoretical concepts, and applications of this technology.

Haustein, Elke; Schwille, Petra

2011-06-17

225

Generalized linear correlation filters

NASA Astrophysics Data System (ADS)

We present two generalized linear correlation filters (CFs) that encompass most of the state-of-the-art linear CFs. The common criteria that arc used in linear CF design are the mean squared error (MSE), output noise variance (ONV), and average similarity measure (ASM). We present a simple formulation that uses an optimal tradeoff among these criteria both constraining and not constraining the correlation peak value, and refer to them as generalized Constrained Correlation Filter (CCF) and Unconstrained Couelation Filter (UCF). We show that most state-of-the-art linear CFs arc subsets of these filters. We present a technique for efficient UCF computation. We also introduce the modified CCF (mCCF) that chooses a unique correlation peak value for each training image, and show that mCCF usually outperforms both UCF and CCF.

Rodriguez, Andres; Vijaya Kumar, B. V. K.

2013-05-01

226

Ozone Correlative Measurements Workshop

NASA Technical Reports Server (NTRS)

A study was conducted to determine the necessary parameters for the correlation of data on Earth ozone. Topics considered were: (1) measurement accuracy; (2) equipment considerations (SBUV); and (3) ground based measurements to support satellite data.

Hilsenrath, E. (editor)

1985-01-01

227

ERIC Educational Resources Information Center

This article, an attempt to "systematize a general theory of lexical correlations and to define and illustrate their categories, is designed to "assist translators, linguists, teachers, writers, learners and all students of language and languages. (FWB)

Newmark, Peter

1969-01-01

228

NASA Astrophysics Data System (ADS)

Some general properties of photon correlations are discussed in a simple way through an analysis of the two-detector measurement scheme. It is shown that the assumption of the discreteness of the random process leads directly to the conclusion that the zero-delay value of the correlation function is only bound to be non-negative. The adopted approach allows discussing in a more intuitive way the photon correlation properties of different optical fields, including non-classical fields presenting an apparent violation of the Cauchy-Schwarz inequality. The comparison between the two- and the single-detector experiment clarifies the role of the operator ordering in the definition of the correlation function.

Degiorgio, V.

2013-10-01

229

Background In instrumented posterolateral fusion reduction of a spondylolisthesis is appealing on theoretical grounds since this may lead to indirect decompression of the entrapped nerve roots. However, there is no consensus in the literature whether a beneficial effect of reduction on outcome can be expected. The objective of the current study was to evaluate whether a correlation between the extent of listhesis reduction and clinical improvement could be established. Methods From two ongoing prospective studies 72 patients with a single-level instrumented posterolateral lumbar fusion for low-grade spondylolisthesis (isthmic/degenerative 51/21) were evaluated. Radiographs and clinical outcome scores were available at baseline, 6 weeks and 1 year after surgery. Changes in neuroforaminal morphology were measured on calibrated radiographs. These changes in radiographic parameters were correlated to clinical outcome (Visual Analogue Score (VAS) leg pain, Oswestry Disability Index (ODI)). Fusion status was assessed on Computed Tomography-scan at one year. Results A mean spondylolisthesis of 25 percent was reduced to 15 percent at 6 weeks with some loss of reduction to 17 percent at one year. The VAS and ODI significantly improved at both time intervals after surgery (p?correlations could be established between the extent of slip reduction and improvement in VAS or ODI (Pearson’s correlation ?0.2 and 0.07 respectively at one year); this also accounted for the other radiographic parameters. A fusion rate of 64 percent was seen on CT-scan. Conclusions Clinical outcome was not related to the obtained radiographic reduction of the slipped vertebra in patients with a lumbar fusion for low grade spondylolisthesis. Loss of reduction or non-union on CT-scans had no effect on the clinical outcome. Reduction of a low-grade spondylolisthesis in spinal fusion is appealing, however, there is no evidence that it positively affects clinical outcome on the short term. Trial registration ISRCTN43648350

2013-01-01

230

NASA Technical Reports Server (NTRS)

Optical cross-correlator indicates position of target (if any) in scene matching target encoded in matched filter. Size reduced by use of prisms to fold optical path. Device designed, assembled from commercial components, and tested to verify feasibility of miniaturization for eventual incorporation into navigational and/or control systems of autonomous vehicles. For example, aircraft equipped with optical correlator recognizes prescribed target and measures its position, so that it lands on target under automatic control.

Scholl, Marija S.; Shumate, Michael S.; Hartman, Richard L.; Sloan, Jeffrey A.; Small, Donald W.

1993-01-01

231

Subexponential decay of correlations

. We describe a method for proving subexponential lower bounds for correlations functions, and apply it to study decay of correlations\\u000a for maps with countable Markov partitions. One result is that LS Young’s upper estimates [Y2] are optimal in many situations.\\u000a Our method is based on a general result concerning the asymptotics of renewal sequences of bounded operators acting on

Omri Sarig

2002-01-01

232

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.

Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde [Department of Radiology, University Hospitals Leuven, 3000 Leuven (Belgium); Departments of Radiology and Biostatistics, University of Iowa, Iowa City, Iowa 52242-1077 and Comprehensive Access and Delivery Research and Evaluation (CADRE) Center, Iowa City VA Health Care System, Iowa City, Iowa 52246-2208 (United States); Department of Radiology, University Hospitals Leuven, 3000 Leuven (Belgium); Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213 (United States); Department of Radiology, University Hospitals Leuven, 3000 Leuven (Belgium)

2012-10-15

233

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.

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

2014-01-01

234

Correlation Between the Intima-Media Thickness of the Proximal and Distal Common Carotids

Background Increased IMT (intima-media thickness) in carotids is used as an early atherosclerosis marker and to evaluate the risk of cardiovascular problems. Ultrasound is used in the evaluation because it is accessible and low cost. Measurements for different carotid regions are described. Objective To compare the proximal and distal region IMTs for the bilateral common carotid and guide its use in clinical practice. Methods The IMT was measured in the proximal and distal common carotid arteries of 798 individuals (35-74 years old) of both genders using high-resolution ultrasound. Pearson's correlation coefficient was used to establish associations. The analyses were initially performed for the entire sample as well as subgroups with IMT <0.90 mm (49% of the sample) and ?0.90 mm for at least one measurement site. The statistical significance was p < 0.05. Results The correlations investigated were significant. In the group with an IMT <0.90 mm, the correlations were between 0.44 and 0.62. In the subgroup with an IMT ?0.90 mm, the correlations were significantly reduced to between 0.20 and 0.40. Conclusion The data suggest that the IMT is more uniform along the carotid during early development and tends develop focally as it progresses. Therefore, in clinical evaluations of patients, the common carotid length should be investigated bilaterally to better use the available software and discern the IMT.

Roelke, Leonard Hermann; Rodrigues, Sergio Lamego; Lotufo, Paulo Andrade; Mill, Jose Geraldo

2013-01-01

235

A Maximum Entropy Test for Evaluating Higher-Order Correlations in Spike Counts

Evaluating the importance of higher-order correlations of neural spike counts has been notoriously hard. A large number of samples are typically required in order to estimate higher-order correlations and resulting information theoretic quantities. In typical electrophysiology data sets with many experimental conditions, however, the number of samples in each condition is rather small. Here we describe a method that allows to quantify evidence for higher-order correlations in exactly these cases. We construct a family of reference distributions: maximum entropy distributions, which are constrained only by marginals and by linear correlations as quantified by the Pearson correlation coefficient. We devise a Monte Carlo goodness-of-fit test, which tests - for a given divergence measure of interest - whether the experimental data lead to the rejection of the null hypothesis that it was generated by one of the reference distributions. Applying our test to artificial data shows that the effects of higher-order correlations on these divergence measures can be detected even when the number of samples is small. Subsequently, we apply our method to spike count data which were recorded with multielectrode arrays from the primary visual cortex of anesthetized cat during an adaptation experiment. Using mutual information as a divergence measure we find that there are spike count bin sizes at which the maximum entropy hypothesis can be rejected for a substantial number of neuronal pairs. These results demonstrate that higher-order correlations can matter when estimating information theoretic quantities in V1. They also show that our test is able to detect their presence in typical in-vivo data sets, where the number of samples is too small to estimate higher-order correlations directly.

Onken, Arno; Dragoi, Valentin; Obermayer, Klaus

2012-01-01

236

ESTIMATION OF WATER QUALITY CRITERIA VIOLATION FREQUENCIES USING PEARSON PERCENTILES

A numerical technique is developed for estimating water quality violation frequencies due to pollutant discharges from urban areas during combined sewer overflow events. The first four moments of in-stream pollutant concentration are found by integrating a pollutant loading - wat...

237

Standardized Pearson type 3 density function area tables

NASA Technical Reports Server (NTRS)

Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods.

Cohen, A. C.; Helm, F. R.; Sugg, M.

1971-01-01

238

The purpose of this cross-sectional pilot study was to determine the prevalence and correlates of depressive symptoms and resiliency among 290 African American women (AAW) in a community-based primary health care center. Descriptive statistics, Pearson product-moment correlation, and logistic regression analyses were conducted. Findings indicate that depressive symptoms are experienced by 49% of the participants, while 10% indicated a history of suicidal ideation. Participants had moderately high resiliency scores that had a statistically significant inverse relationship with depressive symptoms. This suggests that resiliency is potentially a protective factor for depressive symptoms. Depressive symptoms were positively correlated with participants’ diagnosis of at least one chronic disease. The strongest predictors of depressive symptoms were previous diagnoses of a mental health condition and unemployment. This study identifies risk and potential protective factors for depression among a clinic sample of AAW.

Holden, Kisha B.; Bradford, L. Dianne; Hall, Stephanie P.; Belton, Allyson S.

2014-01-01

239

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

240

Advanced quantum noise correlations

NASA Astrophysics Data System (ADS)

We use the quantum correlations of twin beams of light to investigate the fundamental addition of noise when one of the beams propagates through a fast-light medium based on phase-insensitive gain. The experiment is based on two successive four-wave mixing processes in rubidium vapor, which allow for the generation of bright two-mode-squeezed twin beams followed by a controlled advancement while maintaining the shared quantum correlations between the beams. The demonstrated effect allows the study of irreversible decoherence in a medium exhibiting anomalous dispersion, and for the first time shows the advancement of a bright nonclassical state of light. The advancement and corresponding degradation of the quantum correlations are found to be operating near the fundamental quantum limit imposed by using a phase-insensitive amplifier.

Vogl, Ulrich; Glasser, Ryan T.; Clark, Jeremy B.; Glorieux, Quentin; Li, Tian; Corzo, Neil V.; Lett, Paul D.

2014-01-01

241

The evaluation of spectro-temporal receptive fields in auditory neurons makes use of a correlation technique that needs a high amount of calculation time. We present a method in which 2-ms time bins of post-stimulus time histograms, rather than every action potential, are the basis for correlation with the acoustic spectrum of the stimulus. In a t test the content of each bin is classified as excitatory, inhibitory or responseless. The bin width is adjusted to the temporal resolution of the units as determined in a gap detection analysis. The method presented here saves a substantial amount of analysis time and reveals adequately spectro-temporal receptive fields. PMID:8618431

Richard, J P; Leppelsack, H J; Hausberger, M

1995-01-01

242

Objectives: Effective assessment of tissue perfusion is highly important during Coronary Artery Bypass Graft (CABG). Mixed venous O2 saturation (Svo2) is one of the best and routinely used markers of tissue perfusion. However, this method is costly and leads to considerable complications. Thus, the present study aimed to determine whether the Svo2 can be substituted with central venous saturation (Scvo2) and if there is any correlation between lactate level and Svo2. Methods: This prospective observational study was conducted on 62 patients scheduled for CABG. After induction and maintenance of anesthesia, blood samples drawn from central venous, pulmonary artery, and radial artery were used to measure Scvo2, Svo2 and serum lactate level respectively before and after Cardio Pulmonary Bypass (CPB). Pearson’s correlation test was used to determine the correlation between Svo2 and Scvo2 as well as between Svo2 and serum lactate level. Besides, P < 0.05 was considered as statistically significant. Results: Overall, 62 Patients, 33 males (53.2%) and 29 females (46.8%) were enrolled into the present study. The most common coexisting illness was hypertension detected in 33 patients (53.2%) followed by hypercholesterolemia in 28 ones (44.4%). In this study, Svo2 was positively correlated with Scvo2 (r = 0.63, P < 0.001). However, no correlation was found between Svo2 and lactate (r = 0.124, P = 0.348). Conclusions: In summary, Scvo2 is considered as the best substitute of Svo2 for detecting tissue hypo perfusion during CPB. Although the lactate level had been considered as an appropriate marker of tissue perfusion and ischemia, it was not correlated to Svo2 during CABG.

Shahbazi, Shahrbano; Khademi, Saeed; Shafa, Masih; Joybar, Reza; Hadibarhaghtalab, Maryam; Sahmeddini, Mohammad Ali

2013-01-01

243

Correlations and Ostwald ripening

This paper examines the effect of diffusive interactions, and the correlations they create between particles, on Ostwald ripening. The effect accounts for a persistent discrepancy between theory and experiment, in which the distribution of particle sizes has been more broad and flat than mean-field theory predicts. A new model system is proposed to study the problem, and a hierarchy of equations derived from it is expanded in powers of the square root of the volume fraction. The time devlopment of correlations is analyzed through an unusual perturbation theory. The resulting differential equations are solved numerically and compared with experiment.

Marder, M.

1987-07-15

244

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

245

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

246

Correlation between BPI Gene Upstream CpG Island Methylation and mRNA Expression in Piglets

Diarrhea and edematous disease are two major causes of mortality in postweaning piglets, and these conditions lead to huge economic losses in the swine industry. E. coli F18 is the primary causative agent of these two diseases. Bactericidal/permeability-increasing protein (BPI) plays an important role in the natural defense of the host. The aim of this study was to determine the correlation between BPI gene upstream CpG island methylation and mRNA expression. In this study, bisulfite sequencing PCR (BSP) was used to detect the methylation status of the BPI gene upstream CpG island and fluorescence quantitative PCR was used to detect BPI expression in the duodenum of piglets from birth to weaning age. BPI upstream CpG islands were shown to have many putative transcription factor binding sites, 10 CpG sites and every CpG site was methylated. The CpG island methylation level was lowest in 30-day piglets and was significantly lower than levels in 8-day piglets (p < 0.05). BPI mRNA expression was significantly higher in 30-day piglets than at any other age (p < 0.05). Pearson’s correlation analysis showed that the methylation status of the CpG island was negatively correlated with BPI mRNA expression. Statistical significances were found in CpG_1, CpG_3, CpG_4, CpG_7 and CpG_10 (p < 0.05). The data indicate that BPI expression is improved by demethylation of the BPI gene upstream CpG island. Furthermore, CpG_1, CpG_3, CpG_4, CpG_7 and CpG_10 may be critical sites in the regulation of BPI gene expression.

Wang, Jing; Yin, Xuemei; Sun, Li; Sun, Shouyong; Zi, Chen; Zhu, Guoqiang; Wu, Shenglong; Bao, Wenbin

2014-01-01

247

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 (GC×GC/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.

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

2010-01-01

248

Correlations and Ostwald ripening

This paper examines the effect of diffusive interactions, and the correlations they create between particles, on Ostwald ripening. The effect accounts for a persistent discrepancy between theory and experiment, in which the distribution of particle sizes has been more broad and flat than mean-field theory predicts. A new model system is proposed to study the problem, and a hierarchy of

M. Marder

1987-01-01

249

Fitting the correlation function.

The whole correlation function of the intensity of scattered light is usually determined from a single realization of the photocurrent. As a result, the values of the correlation function at different delay times are not statistically independent. A standard least-squares fitting procedure is not optimal for an analysis of such data. However, the benefits of mathematically rigorous but highly nonlinear and less stable methods are not known. We consider the test case of a Gaussian signal with a single-exponential correlation function without shot noise. In this case the fitting procedure, which is based on the maximum-likelihood principle for the observed signal, permits an analytical solution. We demonstrate that such a rigorous statistical analysis produces an approximately two times more-accurate result for the relaxation time than does the standard least-squares fit. This gain, however, is greatly reduced by the presence of shot noise, which introduces additional uncorrelated errors into the values of the correlation function. PMID:18360444

Lomakin, A

2001-08-20

250

Fitting the Correlation Function

NASA Astrophysics Data System (ADS)

The whole correlation function of the intensity of scattered light is usually determined from a single realization of the photocurrent. As a result, the values of the correlation function at different delay times are not statistically independent. A standard least-squares fitting procedure is not optimal for an analysis of such data. However, the benefits of mathematically rigorous but highly nonlinear and less stable methods are not known. We consider the test case of a Gaussian signal with a single-exponential correlation function without shot noise. In this case the fitting procedure, which is based on the maximum-likelihood principle for the observed signal, permits an analytical solution. We demonstrate that such a rigorous statistical analysis produces an approximately two times more-accurate result for the relaxation time than does the standard least-squares fit. This gain, however, is greatly reduced by the presence of shot noise, which introduces additional uncorrelated errors into the values of the correlation function.

Lomakin, Aleksey

2001-08-01

251

NASA Astrophysics Data System (ADS)

The theoretical relationships for determining contact, gap, and joint conductances are developed for conforming rough surfaces for first loading. The dimensionless conductances are functions of the relative contact pressure, surface parameters, conductivity ratio, and a fluid parameter which depends upon several gas and surface characteristics. The proposed conductance correlations are supported quantitatively by some previous experimental results.

Yovanovich, M. M.

252

Point Biserial Correlation Coefficient

NSDL National Science Digital Library

This page calculates the point biserial correlation coefficient for the case where one variable is dichotomous and the other is non-dichotomous. This page allows the user to input the data directly or copy and paste from a spreadsheet application and provides data summary.

Lowry, Richard, 1940-

2008-06-26

253

Correlations in Nuclear Masses

It was recently suggested that the error with respect to experimental data in nuclear mass calculations is due to the presence of chaotic motion. The theory was tested by analyzing the typical error size. A more sensitive quantity, the correlations of the mass error between neighboring nuclei, is studied here. The results provide further support to this physical interpretation.

Olofsson, H.; Aaberg, S. [Division of Mathematical Physics, LTH, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bohigas, O.; Leboeuf, P. [Laboratoire de Physique Theorique et Modeles Statistiques, Batiment 100, Universite de Paris-Sud, 91405 Orsay Cedex (France)

2006-02-03

254

DISCUSS: Regression and Correlation

NSDL National Science Digital Library

This module introduces correlation and regression through topics like scatterplots, lines, slopes, intercepts, applications of regression analysis, the line of best fit, goodness of fit, assumptions and how to check them, prediction, interpolation, extrapolation, and reliability. Excel spreadsheets are used to provide examples and exercises.

Hunt, Neville; Nicholson, James; Tyrrell, Sidney

2009-04-24

255

Correlational Comparison in English

ERIC Educational Resources Information Center

This dissertation proposes a novel analysis of the syntax and semantics of Comparative Correlative sentences in English such as "the bigger they are, the harder they fall or the faster we drive, the sooner we'll get there." The analysis is cast in a framework that distinguishes between argument structure and word order, called…

Smith, Elizabeth Allyn

2011-01-01

256

NASA Astrophysics Data System (ADS)

Similarity transformations and eigenvalue relations of monodromy operators composed of Jordan-Schwinger type L matrices are considered and used to define Yangian symmetric correlators of n-dimensional theories. Explicit expressions are obtained and relations are formulated. In this way basic notions of the Quantum inverse scattering method provide a convenient formulation for high symmetry and integrability not only in lower dimensions.

Chicherin, D.; Kirschner, R.

2013-12-01

257

Correlating Aluminum Burning Times

Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed,

M. W. Beckstead

2005-01-01

258

NSDL National Science Digital Library

This is a graphic correlation lab exercise. It uses real data from a peer-reviewed journal publication by Lucy Edwards (1989). (I have manipulated the data set a little bit.) Students can finish the activity in two hours or less.

Stephen, Dan

259

Optimal real correlation filters

NASA Technical Reports Server (NTRS)

Expressions are derived for real filters that have a maximum correlation signal to noise ratio. Both continuous and discrete cases are treated and shown to have similar forms. The signal can be complex, and the case of a real signal is considered and related to previous results.

Juday, Richard D.; Vijaya Kumar, B. V. K.; Rajan, P. Karivaratha

1991-01-01

260

NASA Astrophysics Data System (ADS)

We present a review of various schemes in which the quenching of spontaneous emission takes place in correlated emission laser (CEL). In particular we discuss Hanle laser, quantum beat laser, and a two-photon CEL. We also discuss noise-free amplification in a two-photon CEL.

Zubairy, M. S.; Qamar, Shahid; Sultana, Sadaf

1992-10-01

261

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.

262

Informationally optimal correlation

This papers studies how to decompose a correlated distribution of actions, as a convex combination of indepedent distribution, in a way that is optimal for an information theory criterion. A characterization of optimal solutions is provided for 2?2 sets of actions. Then we give an application to the exact computation of maxmin values in some repeted games.

Olivier Gossner; Rida Laraki; Tristan Tomala

2009-01-01

263

Aims: The Atacama Large Millimeter Array (ALMA) is an international astronomy facility to be used for detecting and imaging all types of astronomical sources at millimeter and submillimeter wavelengths at a 5000-m elevation site in the Atacama Desert of Chile. Our main aims are: describe the correlator sub-system which is that part of the ALMA system that combines the signal

R. P. Escoffier; G. Comoretto; J. C. Webber; A. Baudry; C. M. Broadwell; J. H. Greenberg; R. R. Treacy; P. Cais; B. Quertier; P. Camino; A. Bos; A. W. Gunst

2007-01-01

264

This is a re-analysis of data from a previous study which examined the temporal stability of three psychophysiological responses [frontal electromyographic activity (EMG), hand surface temperature, and heart rate]. Each response was recorded on 64 subjects over four sessions, each of which consisted of a 20-min, adaptation period, a baseline condition, and two stressors (one cognitive, the other physical). Rather than using Pearson product-moment correlations, as nearly all psychophysiological test-retest reliability studies have, we have now analyzed the data using intraclass correlation coefficients. This type of correlation allows one to incorporate more than two test-retest values on the same subjects. Analysis indicated that, with the exception of EMG during the physical stressor, the absolute values of the responses had quite significant reliability (.70 or greater). Treating the responses as relative measures (percent change from baseline or simple change scores from baseline) produced smaller and frequently less stable coefficients. It is concluded that statistical estimates of psychophysiological response reliability are functions of the design and particular reliability analysis employed. PMID:7770564

Arena, J G; Hobbs, S H

1995-02-01

265

Tryptase-positive mast cells correlate with angiogenesis in early breast cancer patients.

Literature data indicate that mast cells (MCs) are involved in tumor angiogenesis due to the release of several pro-angiogenetic factors among which tryptase, a serine protease stored in MCs granules, is one of the most active. However, no data are available concerning the role of MCs in angiogenesis in primary human breast cancer. In this study, we have evaluated the correlations between the number of MCs positive to tryptase (MCDPT), the area occupied by MCs positive to tryptase (MCAPT) and microvascular density (MVD) and endothelial area (EA) in a series of 88 primary T1-3, N0-2 M0 female breast cancer, by means of immunohistochemistry and image analysis methods. Data demonstrated a significant (r = from 0.78 to 0.89; p-value from 0.001 to 0.002 by Pearson's analysis respectively) correlation between MCDPT, MCAPT, MVD, EA to each other. No correlation concerning MCDPT, MCAPT, MVD, EA and the main clinicopathological features was found. Our results suggest that tryptase-positive MCs play a role in breast cancer angiogenesis. In this context several tryptase inhibitors such as gabexate mesilate and nafamostat mesilate might be evaluated in clinical trials as a new anti-angiogenetic approach. PMID:19513558

Ranieri, Girolamo; Ammendola, Michele; Patruno, Rosa; Celano, Giuseppe; Zito, Francesco Alfredo; Montemurro, Severino; Rella, Addolorata; Di Lecce, Valentina; Gadaleta, Cosmo Damiano; Battista De Sarro, Giovanni; Ribatti, Domenico

2009-07-01

266

The isoflavone diversity (44 varieties) of the soybean, Glycine max (L.) Merrill, from China, Japan, and Korea was examined by high-performance liquid chromatography. The profiles of 12 isoflavones identified from the grains were subjected to data-mining processes, including partial least-squares discriminant analysis (PLS-DA), Pearson's correlation analysis, and hierarchical clustering analysis (HCA). Although PLS-DA did not reveal significant differences among extracts of soybean from 3 countries, the results clearly show that the variation between varieties was low. The CS02554 variety was separate from the others in the first 2 principal components of PLS-DA. HCA of these phytochemicals resulted in clusters derived from closely related biochemical pathways. Daidzin, genistin, and glycitin contents were significantly correlated with their respective malonyl glycoside contents. Daidzein content correlated positively with genistein content (r=0.8189, P<0.0001). The CS02554 variety appears to be a good candidate for future breeding programs, as it contains high levels of isoflavone compounds. These results demonstrate the use of metabolite profiling combined with chemometrics as a tool for assessing the quality of food and identifying metabolic links in biological systems. PMID:24491728

Kim, Jae Kwang; Kim, Eun-Hye; Park, Inmyoung; Yu, Bo-Ra; Lim, Jung Dae; Lee, Young-Sang; Lee, Joo-Hyun; Kim, Seung-Hyun; Chung, Ill-Min

2014-06-15

267

Dietary intake of nutrients and its correlation with fatigue in multiple sclerosis patients

Background The role of nutrition in the progression of multiple sclerosis (MS) and related complications such as fatigue has been reported by several studies. The aim of this study is the assessment of nutritional status and its relationship with fatigue in multiple sclerosis patients. Methods This is a cross-sectional study, in which 101 relapsing-remitting MS patients were enrolled. The fatigue status was determined using the validated Persian version of of the Modified Fatigue Impact Scale (MFIS). Dietary intake was assessed using a 3-day food record questionnaire and compared to dietary reference intake (DRI) values. Association between variables was determined using Pearson Correlation Coefficient. Results In the preset study, 25 men and 76 women (total = 101) were enrolled. Analysis of dietary intake showed that daily intake of vitamin D, folate, calcium, and magnesium were significantly lower than DRI in all of patients. In men, zinc intake was significantly lower than DRI; while, in women, iron was significantly below the DRI level. After adjusting for energy, MFIS and its physical subscale were highly correlated with intake of folate and magnesium. Conclusion Our findings support that lower magnesium and folate diets are correlated with higher fatigue scores in MS patients.

Bitarafan, Sama; Harirchian, Mohammad-Hossein; Nafissi, Shahriar; Sahraian, Mohammad-Ali; Togha, Mansoureh; Siassi, Fereydoun; Saedisomeolia, Ahmad; Alipour, Elham; Mohammadpour, Nakisa; Chamary, Maryam; Honarvar, Niyaz Mohammadzadeh

2014-01-01

268

Correlators in nontrivial backgrounds

Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.

Mello Koch, Robert de [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa); Stellenbosch Institute for Advanced Studies, Stellenbosch (South Africa); Ives, Norman; Stephanou, Michael [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa)

2009-01-15

269

Single nanowire optical correlator.

Integration of miniaturized elements has been a major driving force behind modern photonics. Nanowires have emerged as potential building blocks for compact photonic circuits and devices in nanophotonics. We demonstrate here a single nanowire optical correlator (SNOC) for ultrafast pulse characterization based on imaging of the second harmonic (SH) generated from a cadmium sulfide (CdS) nanowire by counterpropagating guided pulses. The SH spatial image can be readily converted to the temporal profile of the pulses, and only an overall pulse energy of 8 ?J is needed to acquire a clear image of 200 fs pulses. Such a correlator should be easily incorporated into a photonic circuit for future use of on-chip ultrafast optical technology. PMID:24807852

Yu, Huakang; Fang, Wei; Wu, Xiaoqin; Lin, Xing; Tong, Limin; Liu, Weitao; Wang, Aimin; Shen, Y Ron

2014-06-11

270

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

271

Nonlinear correlation spectroscopy (NLCS).

We present a novel concept for optical spectroscopy called nonlinear correlation spectroscopy (NLCS). NLCS analyses coherent field fluctuations of the second and third harmonic light generated by diffusing nanoparticles. Particles based on noncentrosymmetric nonlinear materials such as KNbO(3) show a strong second as well as third harmonic response. The method and the theory are introduced and experimental NLCS results in fetal calf serum are presented showing the promising selectivity of this technique for measurement in complex biological environments. PMID:22372559

Geissbuehler, Matthias; Bonacina, Luigi; Shcheslavskiy, Vladislav; Bocchio, Noelia L; Geissbuehler, Stefan; Leutenegger, Marcel; Märki, Iwan; Wolf, Jean-Pierre; Lasser, Theo

2012-03-14

272

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

273

NASA Astrophysics Data System (ADS)

Interferoceiver is a true correlation receiver and capable of overcoming severe problems caused by conventional super heterodyne receivers, such as range inaccuracy, Doppler range ambiguity, fratricides, excessive clutter contamination, undue inter system interference, etc. We had discussed the above capabilities in our early publications. In this paper, we will present the experimental progresses on interferoceiver as well as encountered obstacles. The technological revolution in radar and electronic warfare is within sight.

Li, Ming-Chiang

2009-05-01

274

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

275

Asymmetric galaxy correlation functions

NASA Astrophysics Data System (ADS)

We study the two-point cross-correlation function between two populations of galaxies: for instance, a bright population and a faint population. We show that this cross-correlation is asymmetric under the exchange of the line-of-sight coordinate of the galaxies, i.e. that the correlation is different if the bright galaxy is in front of, or behind, the faint galaxy. We give an intuitive, quasi-Newtonian derivation of all the effects that contribute to such an asymmetry in large-scale structure: gravitational redshift, Doppler shift, lensing, light-cone, evolution and Alcock-Paczynski effects; interestingly, the gravitational redshift term is exactly canceled by some of the others, assuming geodesic motion. Most of these effects are captured by previous calculations of general relativistic corrections to the observed galaxy density fluctuation; the asymmetry arises from terms that are suppressed by the ratio (H /k)—H is the Hubble constant and k is the wave number—which are more readily observable than the terms suppressed by (H /k)2. Some of the contributions to the asymmetry, however, arise from terms that are generally considered "Newtonian"—the lensing and evolution—and thus represent a contaminant in the search for general relativistic corrections. We propose methods to disentangle these different contributions. A simple method reduces the contamination to a level of ?10% for redshifts z ?1. We also clarify the relation to recent work on measuring gravitational redshifts by stacking clusters.

Bonvin, Camille; Hui, Lam; Gaztañaga, Enrique

2014-04-01

276

NASA Astrophysics Data System (ADS)

Moore’s law is best exploited by using consumer market hardware. In particular, the gaming industry pushes the limit of processor performance thus reducing the cost per raw flop even faster than Moore’s law predicts. Next to the cost benefits of Common-Of-The-Shelf (COTS) processing resources, there is a rapidly growing experience pool in cluster based processing. The typical Beowulf cluster of PC’s supercomputers are well known. Multiple examples exists of specialised cluster computers based on more advanced server nodes or even gaming stations. All these cluster machines build upon the same knowledge about cluster software management, scheduling, middleware libraries and mathematical libraries. In this study, we have integrated COTS processing resources and cluster nodes into a very high performance processing platform suitable for streaming data applications, in particular to implement a correlator. The required processing power for the correlator in modern radio telescopes is in the range of the larger supercomputers, which motivates the usage of supercomputer technology. Raw processing power is provided by graphical processors and is combined with an Infiniband host bus adapter with integrated data stream handling logic. With this processing platform a scalable correlator can be built with continuously growing processing power at consumer market prices.

Schaaf, Kjeld; Overeem, Ruud

2004-06-01

277

Correlation analysis of alveolar bone loss in buccal/palatal and proximal surfaces in rats.

The aim was to correlate alveolar bone loss in the buccal/palatal and the mesial/distal surfaces of upper molars in rats. Thirty-three, 60-day-old, male Wistar rats were divided in two groups, one treated with alcohol and the other not treated with alcohol. All rats received silk ligatures on the right upper second molars for 4 weeks. The rats were then euthanized and their maxillae were split and defleshed with sodium hypochlorite (9%). The cemento-enamel junction (CEJ) was stained with 1% methylene blue and the alveolar bone loss in the buccal/palatal surfaces was measured linearly in 5 points on standardized digital photographs. Measurement of the proximal sites was performed by sectioning the hemimaxillae, restaining the CEJ and measuring the alveolar bone loss linearly in 3 points. A calibrated and blinded examiner performed all the measurements. Intraclass Correlation Coefficient revealed values of 0.96 and 0.89 for buccal/lingual and proximal surfaces, respectively. The Pearson Correlation Coefficient (r) between measurements in buccal/palatal and proximal surfaces was 0.35 and 0.05 for the group treated with alcohol, with and without ligatures, respectively. The best correlations between buccal/palatal and proximal surfaces were observed in animals not treated with alcohol, in sites both with and without ligatures (r = 0.59 and 0.65, respectively). A positive correlation was found between alveolar bone loss in buccal/palatal and proximal surfaces. The correlation is stronger in animals that were not treated with alcohol, in sites without ligatures. Areas with and without ligature-induced periodontal destruction allow detection of alveolar bone loss in buccal/palatal and proximal surfaces. PMID:23184169

Azambuja, Carolina Barrera de; Cavagni, Juliano; Wagner, Marcius Comparsi; Gaio, Eduardo José; Rösing, Cassiano Kuchenbecker

2012-01-01

278

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.

Shahroudi, Atefe Saffar; Etezadi, Tahura

2013-01-01

279

Spatial correlation of hydrometeor occurrence, reflectivity, and rain rate from CloudSat

NASA Astrophysics Data System (ADS)

This paper examines the along-track vertical and horizontal structure of hydrometeor occurrence, reflectivity, and column rain rate derived from CloudSat. The analysis assumes hydrometeors statistics in a given region are horizontally invariant, with the probability of hydrometeor co-occurrence obtained simply by determining the relative frequency at which hydrometeors can be found at two points (which may be at different altitudes and offset by a horizontal distance, ?x). A correlation function is introduced (gamma correlation) that normalizes hydrometeor co-occurrence values to the range of 1 to -1, with a value of 0 meaning uncorrelated in the usual sense. This correlation function is a generalization of the alpha overlap parameter that has been used in recent studies to describe the overlap between cloud (or hydrometeor) layers. Examples of joint histograms of reflectivity at two points are also examined. The analysis shows that the traditional linear (or Pearson) correlation coefficient provides a useful one-to-one measure of the strength of the relationship between hydrometeor reflectivity at two points in the horizontal (that is, two points at the same altitude). While also potentially useful in the vertical direction, the relationship between reflectivity values at different altitudes is not as well described by the linear correlation coefficient. The decrease in correlation of hydrometeor occurrence and reflectivity with horizontal distance, as well as precipitation occurrence and column rain rate, can be reasonably well fit with a simple two-parameter exponential model. In this paper, the North Pacific and tropical western Pacific are examined in detail, as is the zonal dependence.

Marchand, Roger

2012-03-01

280

Psychosocial Correlates of Adolescent Males' Pregnancy Intention

ABSTRACT. Objective. To identify psychosocial dif- ferences between sexually experienced male adolescents who indicate intentions to get someone pregnant and those who do not. Methodology. Cross-sectional study of 101 sexually experienced adolescent males recruited from a sexually transmitted disease clinic in northern California. We used Student’s t tests and regressions to examine psycho- social differences between males who reported any

Cynthia Rosengard; Maureen G. Phipps; Nancy E. Adler; Jonathan M. Ellen

2010-01-01

281

Topological correlations in soap froths

NASA Astrophysics Data System (ADS)

Correlation in two-dimensional soap froth is analyzed with the introduction of two point correlators and topological distance. Cells with an equal number of sides repel (with linear correlation) while cells with a different number of sides attract (with nonbilinear correlation) for nearest neighbors, which cannot be explained by the maximum entropy argument. Also, the analysis indicates that froth is correlated up to the third shell neighbors at least.

Szeto, K. Y.; Aste, T.; Tam, W. Y.

1998-08-01

282

Evaluation of clinical and laboratory correlates of sickle leg ulcers.

The exact mechanism for the occurrence of sickle leg ulcers (SLUs) has not been fully explained, although, popular opinion supports a multifactorial etio-pathogenetic process. Leg ulceration in sickle cell is a chronic and debilitating condition which is difficult to treat and may worsen the psychosocial impact of this illness. This study aims to evaluate the laboratory and clinical correlates of SLUs. One hundred sixty-seven patients who had been diagnosed with sickle cell anemia (homozygous S) had their steady-state hemoglobin concentration (Hb), hematocrit, white cell count, platelet count, serum bilirubin, and aspartate transaminase (AST) as well as frequency of crisis per annum evaluated with respect to their relationship to the occurrence of leg ulcers. They were aged 6-53 years (mean age 24.3 years), and prevalence of leg ulcer was found to be 2.75 per 1000 (2.54 per 1000 in females and 2.83 per 1000 in males). The independent sample t-test showed a significant difference in the serum AST levels in those with SLU (p = 0.029), though a positive correlation did not exist. Other predictors of disease severity found to have positive relationship with each other were the AST and total serum bilirubin 0.207 (p = 0.012); Hb and age 0.130 (p = 0.035); Hb and white cell count -0.159 (p = 0.010), white cell count and age -0.113 (p = 0.018). SLUs do not occur in patients with severe disease in sickle cell. The clinical and laboratory indicators of severe sickle cell disease do not correlate positively with the occurrence of SLU. Serum AST may have a relationship with leg ulceration in these patients. Environmental factors most likely play a major part in the etiopathogenesis of leg ulcer and this may require further studies in different sociocultural settings. PMID:24134724

Madu, Anazoeze Jude; Ubesie, Agozie; Madu, Kenechi Anthony; Okwor, Bismarck; Anigbo, Chukwudi

2013-01-01

283

Cluster-cluster correlations and constraints on the correlation hierarchy

NASA Technical Reports Server (NTRS)

The hypothesis that galaxies cluster around clusters at least as strongly as they cluster around galaxies imposes constraints on the hierarchy of correlation amplitudes in hierachical clustering models. The distributions which saturate these constraints are the Rayleigh-Levy random walk fractals proposed by Mandelbrot; for these fractal distributions cluster-cluster correlations are all identically equal to galaxy-galaxy correlations. If correlation amplitudes exceed the constraints, as is observed, then cluster-cluster correlations must exceed galaxy-galaxy correlations, as is observed.

Hamilton, A. J. S.; Gott, J. R., III

1988-01-01

284

Asthma severity: histopathologic correlations.

Asthma is a disorder characterized by inflammation of the airways which leads to variable airflow obstruction and symptoms of wheezing, chest tightness, cough, and dyspnea. Decisions concerning the type and intensity of therapy for asthma are generally based on the severity of the disease in a given individual. Guidelines for asthma management classify disease severity on the basis of symptom frequency and intensity as well as the degree of physiological impairment. Because treatment decisions are currently not based on markers of airway inflammation, it is important to know how well the underlying inflammatory pathology correlates with clinical and physiological variables and whether airway inflammation, if undertreated, leads to longer term adverse outcomes such as chronic persistent airway obstruction. Studies of asthma pathology reveal an inflammatory response characterized by infiltration of the airways with eosinophils, mast cells and lymphocytes; disruption of the epithelium; thickening of the reticular basement membrane; and increases in smooth muscle mass. These findings are qualitatively found in mild as well as severe asthmatics, and attempts to draw quantitative correlations between severity and intensity of inflammation have yielded discordant results. Although antiinflammatory therapy with corticosteroids decreases the intensity of the inflammation in association with improved clinical variables, the association is circumstantial and it is unclear which marker of inflammation correlates best with the severity of acute episodes or the severity of the disease in patients who are stable. Problems in relating the underlying pathology to disease severity are largely due to inadequate tissue sampling as bronchoscopically obtained specimens do not permit an evaluation of the outer airway wall or small airways and their surrounding parenchyma. PMID:12973422

Fish, J E; Peters, S P

1999-08-01

285

A sensitive and selective high performance liquid chromatographic (HPLC) method was developed and validated for estimation of lamotrigine (CAS 84057-84-1) in human plasma and saliva. The chromatographic separation was achieved with a reversed phase column and a mobile phase consisting of acetonitrile and 20 mM ammonium acetate buffer pH 6.5 (30:70) with a flow rate of 1 mL/min. The calibration curve was linear within the working range for both plasma and saliva. The validated method has been successfully applied for a study of lamotrigine in human plasma and saliva to establish the correlation between these two matrices. A scatter plot of plasma versus salivary lamotrigine concentrations showed a gold linear relationship between them (Pearson correlation coefficient, r = 0.6832, p < 0.001). PMID:21125809

Mallayasamy, Surulivel Rajan; Arumugamn, Karthik; Jain, Tarun; Rajakannan, Thiyagu; Bhat, Krishnamurthy; Gurumadhavrao, Padma; Devarakonda, Ramakrishna

2010-01-01

286

Grayscale Optical Correlator Workbench

NASA Technical Reports Server (NTRS)

Grayscale Optical Correlator Workbench (GOCWB) is a computer program for use in automatic target recognition (ATR). GOCWB performs ATR with an accurate simulation of a hardware grayscale optical correlator (GOC). This simulation is performed to test filters that are created in GOCWB. Thus, GOCWB can be used as a stand-alone ATR software tool or in combination with GOC hardware for building (target training), testing, and optimization of filters. The software is divided into three main parts, denoted filter, testing, and training. The training part is used for assembling training images as input to a filter. The filter part is used for combining training images into a filter and optimizing that filter. The testing part is used for testing new filters and for general simulation of GOC output. The current version of GOCWB relies on the mathematical software tools from MATLAB binaries for performing matrix operations and fast Fourier transforms. Optimization of filters is based on an algorithm, known as OT-MACH, in which variables specified by the user are parameterized and the best filter is selected on the basis of an average result for correct identification of targets in multiple test images.

Hanan, Jay; Zhou, Hanying; Chao, Tien-Hsin

2006-01-01

287

Cluster Correlations from n-Point Correlation Amplitudes.

National Technical Information Service (NTIS)

It is shown, by using a new technique, how the much debated cluster correlation function is directly related to the higher order galaxy correlations. Mathematical techniques from biased galaxy formation are adopted: the biasing simulates the detection of ...

I. Szapudi A. S. Szalay P. Boschan

1991-01-01

288

Background Atherosclerotic plaque progression and rupture are believed to be associated with mechanical stress conditions. In this paper, patient-specific in vivo intravascular ultrasound (IVUS) coronary plaque image data were used to construct computational models with fluid-structure interaction (FSI) and cyclic bending to investigate correlations between plaque wall thickness and both flow shear stress and plaque wall stress conditions. Methods IVUS data were acquired from 10 patients after voluntary informed consent. The X-ray angiogram was obtained prior to the pullback of the IVUS catheter to determine the location of the coronary artery stenosis, vessel curvature and cardiac motion. Cyclic bending was specified in the model representing the effect by heart contraction. 3D anisotropic FSI models were constructed and solved to obtain flow shear stress (FSS) and plaque wall stress (PWS) values. FSS and PWS values were obtained for statistical analysis. Correlations with p?correlation between wall thickness and flow shear stress. The mean Pearson correlation r-value was 0.278?±?0.181. Similarly, 9 out of the 10 patients showed negative correlation between wall thickness and plaque wall stress. The mean Pearson correlation r-value was -0.530?±?0.210. Conclusion Our results showed that plaque vessel wall thickness correlated positively with FSS and negatively with PWS. The patient-specific IVUS-based modeling approach has the potential to be used to investigate and identify possible mechanisms governing plaque progression and rupture and assist in diagnosis and intervention procedures. This represents a new direction of research. Further investigations using more patient follow-up data are warranted.

2014-01-01

289

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

NASA Astrophysics Data System (ADS)

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.

Love, Jeffrey J.; Mursula, Kalevi; Tsai, Victor C.; Perkins, David M.

2011-11-01

290

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

291

Correlation of Neonatal Intensive Care Unit Performance Across Multiple Measures of Quality of Care

Objectives To examine whether high performance on one measure of quality is associated with high performance on others and to develop a data-driven explanatory model of neonatal intensive care unit (NICU) performance. Design We conducted a cross-sectional data analysis of a statewide perinatal care database. Risk-adjusted NICU ranks were computed for each of 8 measures of quality selected based on expert input. Correlations across measures were tested using the Pearson correlation coefficient. Exploratory factor analysis was used to determine whether underlying factors were driving the correlations. Setting Twenty-two regional NICUs in California. Patients In total, 5445 very low-birth-weight infants cared for between January 1, 2004, and December 31, 2007. Main Outcomes Measures Pneumothorax, growth velocity, health care–associated infection, antenatal corticosteroid use, hypothermia during the first hour of life, chronic lung disease, mortality in the NICU, and discharge on any human breast milk. Results The NICUs varied substantially in their clinical performance across measures of quality. Of 28 unit-level correlations only 6 were significant (P < .05). Correlations between pairs of quality measures were strong (? > .5) for 1 pair, moderate (.3 < |?| < .5) for 8 pairs, weak (.1 < |?| < .3) for 5 pairs and negligible (|?| < .1) for 14 pairs. Exploratory factor analysis revealed 4 underlying factors of quality in this sample. Pneumothorax, mortality in the NICU, and antenatal corticosteroid use loaded on factor 1; growth velocity and health care–associated infection loaded on factor 2; chronic lung disease loaded on factor 3; and discharge on any human breast milk loaded on factor 4. Conclusion In this sample, the ability of individual measures of quality to explain overall quality of neonatal intensive care was modest.

Profit, J; Zupancic, JAF; Gould, JB; Pietz, K; Kowalkowski, MA; Draper, D; Hysong, SJ; Petersen, LA

2014-01-01

292

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

293

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

294

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

295

Strongly correlated electronic materials

This is the final report of a 3-year project. Novel electronic materials characterized by strong electronic correlations display a number of unexpected, often extraordinary, properties. These are likely to play a major role in purpose-specific high-technology electronic materials of the future developed for electronic, magnetic, and optical applications. This project sought to develop predictive control of the novel properties by formulating, solving and applying many-body models for the underlying microscopic physics. This predictive control required the development of new analytical and numerical many-body techniques and strategies for materials of varying strengths of interactions, dimensionality and geometry. Results are compared with experiment on classes of novel materials, and the robust techniques are used to predict additional properties and motivate key additional experiments.

Bedell, K.; Albers, R.; Balatsky, A.; Bishop, A.; Bonca, J.; Gubernatis, J.; Gulasci, M.; Silver, R.; Trugman, S.

1996-04-01

296

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

297

Standard Errors for Matrix Correlations.

ERIC Educational Resources Information Center

Derives the asymptotic standard errors and intercorrelations for several matrix correlations assuming multivariate normality for manifest variables and derives the asymptotic standard errors of the matrix correlations for two factor-loading matrices. (SLD)

Ogasawara, Haruhiko

1999-01-01

298

Frequency Correlation in Tropospheric Propagation.

National Technical Information Service (NTIS)

The theoretical correlation of signals with varying frequency spacing for propagation through the troposphere is considered. It seems that certain conclusions on the signal propagation paths can be drawn from the correlation characteristics. The report th...

L. Jonasson

1971-01-01

299

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.

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

2014-01-01

300

The purpose of this study was to evaluate the correlation between the hybrid layer thickness, resin tag length and resin bond strength of a self-etching adhesive system to sound dentin tissue "in vivo". After performing restorative procedures and tooth extractions, ten specimens were sectioned in a mesiodistal direction. One dental section was used for light microscope analysis, in which both the resin tag length and hybrid layer thickness were measured, while the other section was analyzed using a microtensile test (0.5 mm/min). The fractured surface of the latter section was characterized using a stereoscopic magnifying glass (40x magnifcation). The results were subject to statistical analysis using the Pearson Correlation Test (a = 0.05). The hybrid layer thickness, resin tag length and resin bond strength mean values were 2.19 microm (0.34), 4.34 microm (0.28) and 9.73 MPa (5,55), respectively. In addition, correlation tests between the resin tag length and the resin bond strength (r=0.014) and also between the hybrid layer thickness and bond strength (r=0.43), showed no statistically significant correlation. The microtensile bond strength of Adper Prompt L Pop self-etching adhesive system does not depend on hybrid layer thickness or resin tag length. PMID:23230647

Rahal, Vanessa; de Oliveira, Fernanda G; Briso, André L F; dos Santos, Paulo H; Sundefeld, Maria L M M; Sundfeld, Renato H

2012-01-01

301

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

302

Correlation Effects in Quantum Crystals

Correlation effects in the quantum crystals He3 and He4 are studied in detail. The single-particle wave function is obtained in the harmonic effective-field approximation; the parameters of the harmonic-oscillator potential are determined self-consistently from the two-body correlation function and the bare interatomic potential. We determine the two-body correlation function by solving numerically an equation derived by decoupling the three-body correlation

C. Ebner; C. C. Sung

1971-01-01

303

Quantitation of Cytomegalovirus DNA Load in Dried Blood Spots Correlates Well with Plasma Viral Load

An assay to accurately quantitate cytomegalovirus (CMV) load in finger-stick-collected dried blood spots (DBS) could potentially be useful for field studies or for analyzing patient self-collected specimens. We therefore assessed CMV DNA load in paired venipuncture-collected plasma samples and finger-stick DBS, using a previously validated quantitative PCR assay. Assay variability, sensitivity, and changes in viral load during antiviral therapy in finger-stick DBS were compared to the reference plasma quantitative PCR assay, using 106 prospectively collected pairs of finger-stick DBS and plasma samples from 35 solid-organ transplant (SOT) patients. The DBS assay showed good agreement with the reference plasma viral load assay on the log10 scale (Pearson correlation coefficient, 0.92; P < 0.001). The 95% limit of detection of the DBS assay was estimated at 2,700 plasma copies/ml (675 plasma IU/ml). In 94% (76/81) of paired DBS and plasma samples above the limit of detection, the difference in CMV load was <1 log10. CMV viral load changes during antiviral treatment were comparable in plasma and DBS. We conclude that finger-stick DBS provides a convenient sample type for quantitation of CMV load that correlates well with plasma levels. Future studies to optimize and evaluate this methodology for patient self-collected samples are warranted.

Santo Hayes, Tracy K.; Huang, Meei-Li; Magaret, Amalia; Boeckh, Michael; Jerome, Keith R.

2013-01-01

304

Objective The mode of influence of the aromas of plant essential oils on human behaviour is largely unclear. This study was designed to assess the potential pharmacological relationships between absorbed 1,8-cineole following exposure to rosemary aroma, cognitive performance and mood. Methods Twenty healthy volunteers performed serial subtraction and visual information processing tasks in a cubicle diffused with the aroma of rosemary. Mood assessments were made pre and post testing, and venous blood was sampled at the end of the session. Pearson correlations were carried out between serum levels of 1,8-cineole, cognitive performance measures and change in mood scores. Results Here we show for the first time that performance on cognitive tasks is significantly related to concentration of absorbed 1,8-cineole following exposure to rosemary aroma, with improved performance at higher concentrations. Furthermore, these effects were found for speed and accuracy outcomes, indicating that the relationship is not describing a speed–accuracy trade off. The relationships between 1,8-cineole levels and mood were less pronounced, but did reveal a significant negative correlation between change in contentment and plasma 1,8-cineole levels. Conclusion These findings suggest that compounds absorbed from rosemary aroma affect cognition and subjective state independently through different neurochemical pathways.

Oliver, Lorraine

2012-01-01

305

Interaural correlation discrimination from diffuse field reference correlations.

Just noticeable differences in interaural correlation (?-jnds) from diffuse sound field reference correlations are obtained. In a three-interval, three-alternative forced-choice procedure, ?-jnds are measured for positive and negative deviations from nine narrowband reference conditions. Stimuli are 1 equivalent rectangular bandwidth wide noise bursts with center frequencies between 165 and 1500 Hz. The frequency dependent reference correlation (?ref) is determined by the simulated interaural correlation under ideal diffuse sound field conditions. Results show that the interaural correlation at threshold for deviation toward the positive correlation range follows the reference curve in a nonlinear fashion. For deviation toward the negative correlation range the interaural correlation at threshold is further afar the reference curve and does not markedly resemble its trend. The results indicate that the previously found asymmetry for correlation discrimination from uncorrelated broadband stimuli to the positive and negative correlation range becomes less pronounced for narrowband stimuli. For positive deviation, the highest jnds are found for the region where the reference curve occupies the global minimum in ?ref; despite that, the interaural correlation at threshold for positive deviation exhibits its lowest value at that point. PMID:23464020

Walther, Andreas; Faller, Christof

2013-03-01

306

Correlations in the Grover search

NASA Astrophysics Data System (ADS)

The Grover search is a well-known quantum algorithm that outperforms any classical search algorithm. It is known that quantum correlations such as entanglement are responsible for the power of some quantum information protocols. But entanglement is not the only kind of quantum correlations. Other quantum correlations such as quantum discord are also useful to capture some important properties of the nonclassical correlation. Also there is no well-accepted and clear distinction between quantum correlations and classical correlations. In this paper, we systematically investigate several kinds of correlations including both quantum and classical in the whole process of the Grover search algorithm. These correlations are the concurrence, entanglement of formation, quantum discord, classical correlation and mutual information. The behaviors of quantum discord, classical correlation and mutual information are almost the same while the concurrence is different in the qubit-qubit case. For the qubit partition 1: n case, the behaviors of all correlations are qualitative the same. When the search is over, all kinds of correlations are zero, we argue that this is necessary for the final step in the search.

Cui, Jian; Fan, Heng

2010-01-01

307

The 512-channel correlator controller

NASA Technical Reports Server (NTRS)

A high-speed correlator for radio and radar observations was developed and a controller was designed so that the correlator could run automatically without computer intervention. The correlator controller assumes the role of bus master and keeps track of data and properly interrupts the computer at the end of the observation.

Brokl, S. S.

1976-01-01

308

Strongly Correlated Electronic Systems

NASA Astrophysics Data System (ADS)

This dissertation presents several explorations into the field of many-body physics. In chapters 1-3 the fundamental nature of many-body interactions in quantum antiferromagnets is scrutinized. Chapter 1 surveys the modern theory of magnetic insulators, focusing on quantum antiferromagnets. Chapter 2 presents an improved method for computing expectation values of local operators in fully Gutzwiller -projected variational states. This embedded cluster method allows accurate extrapolation to the thermodynamic limit when the correlations are sufficiently short-range. The method is used to calculate static spin-spin correlations in a variety of one- and two-dimensional variational states for quantum antiferromagnets. Section 2.3.3 presents a study of the Heisenberg spin Hamiltonian on several lattices using Gutzwiller-projected variational wavefunctions with non-zero Neel order. The variational energies are comparable to more sophisticated calculations, suggesting that these variational wavefunctions are close to the true ground state wavefunction of the Heisenberg antiferromagnet. Chapter 3 discusses Gutzwiller-projected variational wavefunctions for charged, spinless holon excitations in chiral spin liquids. We find that these states describe anyons, with a statistical phase Phi_ {s} that is continuously adjustable between 0 and pi/2, depending on a variational parameter. The statistical flux attached to each holon is localized to within a lattice constant. Chapters 4 and 5 consider a superconducting and a magnetically ordered system, respectively, with the aim of understanding the many-body effects phenomenologically. Chapter 4 presents a self-contained overview of solid Buckminsterfullerene, C_{60}, with an emphasis on those aspects relevant to superconductivity. A BCS theory for superconductivity based on phonon-mediated electron pairing is also presented in some detail. In this model, the isotope effect is the most direct experimental indicator of the role played by phonons in the electron-electron pairing. The superconducting transition temperature of doped C_{60 } is unusually sensitive to partial substitution of ^{13}C for the naturally abundant isotope ^{12}C. Section 4.6 presents the theoretical temperature -dependent resistivity rho(T) resulting from a complete theory of the phonons in rm K_3C_{60} and rm Rb_3C_{60}. The electron-phonon couplings are derived from the theory highlighted in chapter 4. The theory accounts for the unusual non -linear temperature dependence in rho(T). . Finally, chapter 5 reviews several experiments on a variety of magnetic multi-layer and sandwich structures are reviewed. These systems have revealed an indirect exchange coupling between layers of ferromagnets separated by nonmagnetic spacer layers. This coupling oscillates from ferromagnetic to antiferromagnetic depending on the thickness of the spacer layers, with an anomalously long period. (Abstract shortened by UMI.).

Deaven, David Matthew

309

Designed to create composites of eating behavior questionnaire items and determine their relationship to an obesity index within three subsamples of participants in three Navy-sponsored weight-reduction programs (N = 1,878). After item and scale analyses were performed on questionnaire items that pertained to eating behaviors, history of weight problems, activities, and feelings about food and dieting, scores for the resultant composites were computed for individuals within the three subsamples. Results of multiple-regression analyses indicated that the strongest correlates of obesity within each subsample were the Overweight History, Food Obsession, and Activities composites; the multiple R was .49 for Marine recruits, .46 for the other male subsample, and .32 for women. The Emotional Eater composite was included in the multiple regression for the women's subsample. Personality characteristics also were found to be associated with the obesity index in the men's and women's subsamples. Future studies will examine the value of these variables as predictors of weight loss and maintenance of weight loss. PMID:7440750

Hoiberg, A; Berard, S P; Watten, R H

1980-10-01

310

Anatomical correlates of blepharospasm

Background Focal dystonia is a neurological disorder characterized by unwanted muscle spasms. Blepharospasm is a focal dystonia producing an involuntary closure of the eyelid. Its etiology is unknown. Objective To investigate if there are structural changes in the white and grey matter of blepharospasm patients, and if the changes are related to disease features. Methods T1 and diffusion-weighted magnetic resonance imaging scans were collected from 14 female blepharospasm patients and 14 healthy matched controls. Grey matter volumes, fractional anisotropy (FA), and mean diffusivity maps were compared between the groups. Based on grey matter differences within the facial portion of the primary motor cortex, the corticobulbar tract was traced and compared between groups. Results Changes in grey matter in patients included the facial portion of the sensorimotor area and anterior cingulate gyrus. These changes did not correlate with disease duration. Corticobulbar tract volume and peak tract connectivity were decreased in patients compared with controls. There were no significant differences in FA or mean diffusivity between groups. Conclusions Grey matter changes within the primary sensorimotor and the anterior cingulate cortices in blepharospasm patients may help explain involuntary eyelid closure and the abnormal sensations often reported in this condition.

2012-01-01

311

Spectral correlates lexical prosody

NASA Astrophysics Data System (ADS)

The purpose of this study is to derive a quantitative acoustic model of lexical-prosodic characteristics of stressed vowels by looking at several spectral properties associated with the articulatory mechanisms used in speech production. Native speakers of American English were asked to name disyllabic visualizable nouns. Words containing liquids or glides were not used in this study because of their effect on the spectra of adjacent vowels. Subjects uttered short phrases in which the target word was pitch accent half of the time and unaccented the other half. Results show that within the category of full vowels, unstressed and stressed vowels can be distinguished by syllable/vowel durations and spectral tilt. Spectral tilt (SpT) is an acoustic measure related to the degree of glottal spreading. Stressed full vowels had longer duration and less SpT. Distinction between unaccented and accented stressed vowels can be made by amplitude of voicing (AV), F0 (pitch), and intensity contour differences. Accented stressed vowels have higher pitch, and greater AV and intensity. These results suggest that there are acoustic correlates to lexical stress that can be used to determine the stressed syllable of a word, regardless of whether or not it is pitch accented. [Work supported by NIH T32-DC00038.

Okobi, Anthony

2005-09-01

312

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

313

Inter-Subject Correlation in fMRI: Method Validation against Stimulus-Model Based Analysis

Within functional magnetic resonance imaging (fMRI), the use of the traditional general linear model (GLM) based analysis methods is often restricted to strictly controlled research setups requiring a parametric activation model. Instead, Inter-Subject Correlation (ISC) method is based on voxel-wise correlation between the time series of the subjects, which makes it completely non-parametric and thus suitable for naturalistic stimulus paradigms such as movie watching. In this study, we compared an ISC based analysis results with those of a GLM based in five distinct controlled research setups. We used International Consortium for Brain Mapping functional reference battery (FRB) fMRI data available from the Laboratory of Neuro Imaging image data archive. The selected data included measurements from 37 right-handed subjects, who all had performed the same five tasks from FRB. The GLM was expected to locate activations accurately in FRB data and thus provide good grounds for investigating relationship between ISC and stimulus induced fMRI activation. The statistical maps of ISC and GLM were compared with two measures. The first measure was the Pearson's correlation between the non-thresholded ISC test-statistics and absolute values of the GLM Z-statistics. The average correlation value over five tasks was 0.74. The second was the Dice index between the activation regions of the methods. The average Dice value over the tasks and three threshold levels was 0.73. The results of this study indicated how the data driven ISC analysis found the same foci as the model-based GLM analysis. The agreement of the results is highly interesting, because ISC is applicable in situations where GLM is not suitable, for example, when analyzing data from a naturalistic stimuli experiment.

Pajula, Juha; Kauppi, Jukka-Pekka; Tohka, Jussi

2012-01-01

314

Substantial amounts of tooth minerals are lost during dental caries formation. Transversal microradiography, a well-accepted method used to quantify mineral loss, is a time-consuming technique which requires a thin enamel section (100 microns) and involves the use of x-rays. In an attempt to solve these difficulties, a procedure has been developed in which a human tooth specimen with demineralized enamel is cut in half (HT), stained with a fluorescent dye (rhodamine B) and analyzed using a laser scanning confocal microscope. A series of three studies was conducted to correlate measurements of enamel demineralization obtained from enamel thin (100 microns) sections (TS) using transversal microradiography with three parameters (area of the lesion; total and average dye fluorescence intensities) measured on the same TS or on a thicker section (HT) of the same specimen by laser scanning confocal microscopy. Results showed that a 0.1 mM rhodamine B solution provided the most adequate imaging conditions for confocal microscopy. Pearson's correlation coefficients, calculated between microradiography and confocal microscopy data obtained using a 0.1 mM rhodamine B solution, were: delta Z vs. HT lesion area = 0.95; delta Z vs. HT total fluorescence = 0.80; delta Z vs. HT average fluorescence = 0.74; delta Z vs. TS lesion area = 0.95; delta Z vs. TS total fluorescence = 0.74; delta Z vs. TS average fluorescence = 0.55. All these correlations coefficients were statistically significant (p < 0.01). It is concluded that in enamel demineralization studies statistically significant correlations exist between parameters measured using transversal microradiography and parameters quantified using confocal microscopy. PMID:8877084

Fontana, M; Li, Y; Dunipace, A J; Noblitt, T W; Fischer, G; Katz, B P; Stookey, G K

1996-01-01

315

In this clinical study, DIAGNOdent (KaVo) was used to assess previously diagnosed carious lesions in the pits and fissures of first and second molars. The measurements from this device were correlated with the depth and volume of the cavity preparations that resulted from minimal intervention to remove occlusal carious lesions. Twenty-five patients, 18 years of age and older, who were previously scheduled for an occlusal restoration due to caries, were recruited and enrolled in this clinical study. These patients had 48 qualifying teeth without previous restorations, sealants or other carious lesions. The occlusal surface of each study tooth was cleaned utilizing ProphyFlex2 (KaVo). Two dentists separately traced the pit and fissure system of each tooth using DIAGNOdent for two 15-second periods each. The peak reading of each of the four measurements was recorded. An impression of the occlusal surface of each tooth was recorded with a polyvinyl siloxane bite registration material. The carious lesions were removed with an air abrasion unit employing a 0.015-inch nozzle opening utilizing minimal operative intervention. A low viscosity polyvinyl siloxane was used to take an impression of the cavity preparation impression, using the bite registration impression to form the occlusal surface of the preparation impression. The preparation impression volume was calculated from its weight, using the known density of the impression material. The greatest depth of the preparation was measured. The Pearson correlation coefficient was used to investigate any relationship between depth or volume of the preparation impression and the DIAGNOdent measurements. The correlation for preparation volume and maximum DIAGNOdent measurement was 0.191 (p = 0.189). Other logical subsets of cases also did not result in any statistically significant correlations between the DIAGNOdent readings and the depth or volume of the final cavity preparations. PMID:16802636

Hamilton, James C; Gregory, William A; Valentine, John B

2006-01-01

316

Background/Aims: In Saudi Arabia, colorectal cancers (CRCs) are registered as the second most common cancers. However, no data has been reported about correlation of the severity of the anemia and pretreatment platelets level with clinicopathological features of CRCs. We aimed to evaluate the association between pretreatment hemoglobin and platelets level and the clinicopathological features of CRC patients in Saudi Arabia. Materials and Methods: Between September 2005 and November 2011, One hundred and fifty-four confirmed CRC patients underwent thorough physical examination, blood investigations, endoscopic ultrasonography (EUS), and computed tomography (CT) for staging before surgery. Findings of physical assessment, EUS, CT, and pathological specimens were correlated with pretreatment hemoglobin and platelets levels the Pearson-Kendall tau correlative coefficients. Results: The mean age of cohort was 56.6 years (range: 26-89). Left-sided CRC were predominant (97 patients; 63%). Mean size of primary tumor was 6 cms (1-18) SD ± 3.55. Mean values of hemoglobin, red blood cells, hematocrit, white blood cells, and platelets were 11.9 SD ± 2.3, 35.5 SD ± 5.7, 4.43 × 106/mL SD ± 0.6, 7.67 106/mL SD ± 2.44, and 343 × 103/mL SD ± 164.4, respectively. Pretreatment hemoglobin was inversely correlated with primary tumor size (R: 0.71, R2: 1.55, P = 0.0001) and nodal status (R: 0.02, R2: 0.05, P = 0.01). Right-sided CRC had significantly low pretreatment hemoglobin levels (P = 0.001). Interestingly, pretreatment thrombocytosis was seen only in right-sided CRC (P = 0.0001). Conclusion: Pretreatment anemia and thrombocytosis were found mainly in right-sided CRCs and advanced primary and nodal stages. Pretreatment hemoglobin and thrombocytosis can be considered as useful prognostic markers in CRC patients.

Al-Saeed, Eyad F.; Tunio, Mutahir A.; Al-Obaid, Omar; Abdulla, Maha; Al-Anazi, Alaa; Al-Shanifi, Jumanah; Al-Ameer, Leena; Al-Obaidan, Tarfah

2014-01-01

317

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

318

Background/Aims: In Saudi Arabia, colorectal cancers (CRCs) are registered as the second most common cancers. However, no data has been reported about correlation of the severity of the anemia and pretreatment platelets level with clinicopathological features of CRCs. We aimed to evaluate the association between pretreatment hemoglobin and platelets level and the clinicopathological features of CRC patients in Saudi Arabia. Materials and Methods: Between September 2005 and November 2011, One hundred and fifty-four confirmed CRC patients underwent thorough physical examination, blood investigations, endoscopic ultrasonography (EUS), and computed tomography (CT) for staging before surgery. Findings of physical assessment, EUS, CT, and pathological specimens were correlated with pretreatment hemoglobin and platelets levels the Pearson-Kendall tau correlative coefficients. Results: The mean age of cohort was 56.6 years (range: 26-89). Left-sided CRC were predominant (97 patients; 63%). Mean size of primary tumor was 6 cms (1-18) SD ± 3.55. Mean values of hemoglobin, red blood cells, hematocrit, white blood cells, and platelets were 11.9 SD ± 2.3, 35.5 SD ± 5.7, 4.43 × 10 6 /mL SD ± 0.6, 7.67 10 6 /mL SD ± 2.44, and 343 × 10 3 /mL SD ± 164.4, respectively. Pretreatment hemoglobin was inversely correlated with primary tumor size (R: 0.71, R2: 1.55, P = 0.0001) and nodal status (R: 0.02, R2: 0.05, P = 0.01). Right-sided CRC had significantly low pretreatment hemoglobin levels ( P = 0.001). Interestingly, pretreatment thrombocytosis was seen only in right-sided CRC (P = 0.0001). Conclusion: Pretreatment anemia and thrombocytosis were found mainly in right-sided CRCs and advanced primary and nodal stages. Pretreatment hemoglobin and thrombocytosis can be considered as useful prognostic markers in CRC patients. PMID:24705152

Al-Saeed, Eyad F; Tunio, Mutahir A; Al-Obaid, Omar; Abdulla, Maha; Al-Anazi, Alaa; Al-Shanifi, Jumanah; Al-Ameer, Leena; Al-Obaidan, Tarfah

2014-01-01

319

Background An association between tumor-specific HMG-CoA reductase (HMGCR) expression and good prognosis has previously been demonstrated in breast and ovarian cancer. In this study, the expression, clinicopathological correlates and prognostic value of HMGCR expression in colorectal cancer was examined. Findings Immunohistochemical expression of HMGCR was assessed in tissue microarrays with primary tumours from 557 incident cases of colorectal cancer in the Malmö Diet and Cancer Study. Pearson’s Chi Square test was applied to explore the associations between HMGCR expression and clinicopathological factors and other investigative biomarkers. Kaplan Meier analysis and Cox proportional hazards modeling were used to assess the relationship between HMGCR expression and cancer-specific survival (CSS) according to negative vs positive HMGCR expression. A total number of 535 (96.0%) tumours were suitable for analysis, of which 61 (11.4%) were HMGCR negative. Positive cytoplasmic HMGCR expression was associated with distant metastasis-free disease at diagnosis (p = 0.002), lack of vascular invasion (p = 0.043), microsatellite-instability (p = 0.033), expression of cyclin D1 (p = <0.001) and p21 (p = <0.001). Positive HMGCR expression was significantly associated with a prolonged CSS in unadjusted Cox regression analysis in the entire cohort (HR = 1.79; 95% CI 1.20-2.66) and in Stage III-IV disease (HR = 1.71; 95% CI 1.09-2.68), but not after adjustment for established clinicopathological parameters. Conclusions Findings from this prospective cohort study demonstrate that HMGCR is differentially expressed in colorectal cancer and that positive expression is associated with favourable tumour characteristics and a prolonged survival in unadjusted analysis. The utility of HMGCR as a predictor of response to neoadjuvant or adjuvant statin treatment in colorectal cancer merits further study. Virtual slides The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2115647072103464.

2014-01-01

320

Quantum correlations in spin models

Bell nonlocality, entanglement and nonclassical correlations are different aspects of quantum correlations for a given state. There are many methods to measure nonclassical correlations. In this paper, nonclassical correlations in two-qubit spin models are measured by the use of measurement-induced disturbance (MID) [S. Luo, Phys. Rev. A 77 (2008) 022301] and geometric measure of quantum discord (GQD) [B. Dakic, V. Vedral, C. Brukner, Phys. Rev. Lett. 105 (2010) 190502]. Their dependences on external magnetic field, spin-spin coupling, and the Dzyaloshinskii-Moriya (DM) interaction are presented in detail. We also compare Bell nonlocality, entanglement measured by concurrence, MID and GQD and illustrate their different characteristics. - Highlights: > Various quantum correlations in spin models are investigated. > Nonclassical correlations are measured by measurement-induced disturbance and Geometric measure of quantum discord. > Also, we investigate Bell nonlocality and concurrence. > We compare these quantum quantities and illustrate their different characteristics.

Zhang Guofeng, E-mail: gf1978zhang@buaa.edu.cn [Department of Physics, School of Physics and Nuclear Energy Engineering, Beihang University, Xueyuan Road No. 37, Beijing 100191 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Fan Heng; Ji Ailing [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang Zhaotan [Department of Physics, Beijing Institute of Technology, Beijing 100081 (China); Abliz, Ahmad [School of Mathematics, Physics and Informatics, Xinjiang Normal University, Urumchi 830054 (China); Liu Wuming [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2011-10-15

321

Dealing with circular correlation effects

NASA Astrophysics Data System (ADS)

Discrete Fourier transforms (DFTs) are typically used to compute correlations and implementing correlation filters (CFs). Because of the properties of DFTs, resulting correlations are actually circular (also known as periodic) correlations. Using current CF design techniques, it is not possible to design a CF that produces exactly the desired linear correlation output. There are several techniques that may be used to reduce the effects of circular correlation. In this paper, we describe these techniques and provide some experimental results that compare these techniques. This work is sponsored by the Air Force Research Laboratory (AFRL). The views and conclusions contained in this document are those of the authors and should not be interpreted as representing offcial policies, either expressed or implied, of AFRL, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. This document is approved for public released via PA#: 88ABW-2013-1359.

Rodriguez, Andres; Vijaya Kumar, B. V. K.

2013-05-01

322

Image correlation and sampling study

NASA Technical Reports Server (NTRS)

The development of analytical approaches for solving image correlation and image sampling of multispectral data is discussed. Relevant multispectral image statistics which are applicable to image correlation and sampling are identified. The general image statistics include intensity mean, variance, amplitude histogram, power spectral density function, and autocorrelation function. The translation problem associated with digital image registration and the analytical means for comparing commonly used correlation techniques are considered. General expressions for determining the reconstruction error for specific image sampling strategies are developed.

Popp, D. J.; Mccormack, D. S.; Sedwick, J. L.

1972-01-01

323

Influence of Outliers on Correlation

NSDL National Science Digital Library

This activity begins with an instructor demonstration followed by a student out-of-class assignment. Students will observe their instructor create a scatter plot and observe how the correlation coefficient changes when outlier points are added. Students are then given a follow up assignment, which guides them through the applet. In addition, the assignment provides insight about outliers and their effect on correlation. This activity will show exactly how outliers numerically change the correlation coefficient value and to what degree.

Arroway, Pam; Gratton, Jennifer; Stanislav, Steve; Woodard, Roger

2009-02-03

324

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

325

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

326

Why Are Experts Correlated? Decomposing Correlations between Judges

ERIC Educational Resources Information Center

We derive an analytic model of the inter-judge correlation as a function of five underlying parameters. Inter-cue correlation and the number of cues capture our assumptions about the environment, while differentiations between cues, the weights attached to the cues, and (un)reliability describe assumptions about the judges. We study the relative…

Broomell, Stephen B.; Budescu, David V.

2009-01-01

327

NASA Astrophysics Data System (ADS)

It is now widely recognized that the El Niño - Southern Oscillation (ENSO) influences many different meteorological phenomena across the globe. Specifically, ENSO is capable of changing synoptic-scale atmospheric dynamics leading to anomalous temperature, precipitation, and severe weather distributions across the North American continent. Here we establish a potential teleconnection between ENSO and the lightning variability across the United Sates, using a new lightning dataset from the National Climatic Data Center (NCDC), which includes cloud-to-ground (CG) lightning rates from the National Lightning Detection Network (NLDN) extending from 1986 to the present. This new lightning dataset provides an unprecedented opportunity to perform a long-term correlative study between the ENSO and the associated lightning variability across the United States. Pearson correlation coefficients were calculated over multiple timescales (e.g., monthly, yearly, and interannual) between two different ENSO Indices (i.e., Oceanic Niño Index and Multivariate ENSO Index) and anomalous lightning rates. Our results show that the intensity of ENSO coupled with a short-duration transition from El Niño to La Niña conditions (or vice-versa) lead to a statistically significant correlation between ENSO and lightning anomalies. Results from this study provide the initial framework required to pursue our ultimate research goal, which is to potentially find a linkage between ENSO and lightning-induced electron precipitation (LEP) events across the United States.

Jones, M.; Forbes, J. M.

2013-12-01

328

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

329

Correlation of general anxiety and dental anxiety in children aged 3 to 5 years: A clinical survey

Background: The aim of this study was to determine the prevalence of dental anxiety in a group of children aged 3 to 5 years and to explore the relationships between dental anxiety and general fearful nature of the child. Materials & Methods: A total of 250 children were selected for the study after due selection via inclusion criteria. Pre-school anxiety scale by Spence and Rapee (1999) was used to assess the general fear of the child and was filled by the parent during the first visit. Venham’s anxiety scale was used to assess the dental anxiety which was seen during routine dental examination of the child on his first visit. Results: The results were statistically analyzed using Chi square test and Karl Pearson coefficient of correlation. Conclusion: It was concluded that 24% of children showed association between high level of dental anxiety and high level of general fear; 56% of children also exhibited high level of dental anxiety with moderate score of general fear and 20% of children exhibited positive correlation between low level of dental anxiety and fear. How to cite this article: Nigam AG, Marwah N, Goenka P, Chaudhry A. Correlation of general anxiety and dental anxiety in children aged 3 to 5 years: A clinical survey. J Int Oral Health 2013;5(6):18-24 .

Nigam, Anant Gopal; Marwah, Nikhil; Goenka, Puneet; Chaudhry, Ajay

2013-01-01

330

One of the major causes leading to increased antibiotic resistance is excess antimicrobial consumption. We have analysed the correlation between antibiotic use and frequency of carbapenem-resistant Pseudomonas aeruginosa (CRPA) strains in the general intensive care unit of a university hospital Antibiotic use was expressed as number DDD (daily defined doses)/100 occupied hospital bed-days (BD). CRPA incidence rates were determined by number of unique isolates reported to 100,000 BD. The average use of antibiotics between January and August 2008 was 174 DDD/100 BD. The first four most frequently prescribed antibiotics were as follows: first and second generation cephalosporins (47 DDD/100 BD), carbapenemns (29 DDD/100 BD), fluoroquinolones (26 DDD/100 BD) and glycopeptids (20 DDD/100 BD). Average monthly incidence rate of CRPA was 546/100,000 BD (319-773/100,000 BD. CI 95%). There was a correlation between CRPA incidence rate and carbapenem plus fluoroquinolone use (Pearson coefficient of correlation r = 0.7, p < 0.05). Our data showed that the evolution of CRPA incidence rates was related to carbapenem and fluoroquinolone use. PMID:21553483

Székely, Edit; Bucur, Gabriela; Vass, Levente; Butiurca, Manuela; Bilca, Doina; Foldes, Annamaria; Lorinczi, Lilla

2010-01-01

331

Ferromagnetism and electronic correlations

NASA Astrophysics Data System (ADS)

Ferromagnetism belongs to the oldest phenomena in solid state physics being, however, even today not yet fully understood. The main shortcoming for an understanding of this basic phenomenon is the lack of a general, unified theory. The different types of magnetic materials need for their description rather different theoretical models, each of them with a fairly restricted range of validity. To avoid misunderstandings it is therefore recommendable to start the discussion with a simple but clear classification of magnetism and to address the respective theoretical models to the appropriate classes of materials (Sect. I). The most prominent models are inspected in detail in the following sections. For an at least qualitative description of ferromagnets with itinerant magnetic moments (bandferromagnets) the single-band Hubbard model is considered a good starting point. It poses a highly non-trivial many-body problem. Basic concepts and methods of many-body theory are therefore shortly introduced (Sect. II) as far as they are vital for the understanding of the following: Green functions, spectral densities, selfenergies, quasiparticles, quasiparticle densities of states, quasiparticle bandstructures, Starting with the Hubbard-Hamiltonian and several exactly solvable limiting cases are discussed (Sect. II). The latter are important for the construction of reliable approaches to the not rigorously tractable many-body problem. Examples are the zero-bandwidth limit, the strong coupling behavior of the spectral density, weak coupling perturbational treatments, and high-energy expansions. We try a systematic improvement in the evaluation of the Hubbard-Hamiltonian by a series of analytic approximations fulfilling certain sum rules of the spectral density and the above-mentioned exact limiting cases (Sect. III). Starting from two-pole approaches (Hubbard I, spectral density approach (SDA), ...) via different alloy analogies and some applications of dynamical mean field theory we come to a conclusion for a magnetic phase diagram. The calculated Curie temperatures are compared with numerically essentially exact, recent Quantum-Monte Carlo calculations for infinite-dimensional lattices. The role of physically decisive correlation functions, which lead to bandshifts and bandwidth corrections, and the quasiparticle damping on the stability of (ferro) magnetism is investigated. While the Hubbard model gives a frame for the itinerant moment systems the so-called s-f model is used to describe magnetic materials (insulators, semiconductors, metals) which take their magnetic properties from localized moments. It traces back the characteristic features of these systems to an interband exchange interaction between localized magnetic electrons (f) and itinerant conduction electrons (s). It is in principle identical to the Kondo-lattice and the double-exchange model. As a typical consequence of the s-f exchange a new quasiparticle appears which is called the magnetic polaron. It can be calculated exactly for a non-trivial special case. A selfenergy approach combined with a modified RKKY-theory is proposed to determine selfconsistently the electronic and the magnetic properties of the exchange-coupled s and f electrons. .

Nolting, W.

2000-07-01

332

Allergic rhinitis (AR) symptoms can impart emotional, quality of life (QOL), and work productivity burdens, especially in persistent AR (PER). Desloratadine, an H1-receptor antagonist, has been shown to be effective against nasal and nonnasal AR symptoms and to improve QOL. Exploratory analyses were conducted to evaluate whether desloratadine-mediated symptom improvement correlated with improvements in QOL and productivity. The Aerius Control: Clinical and Evaluative Profile of Treatment 2 (NCT00405964) study was a 12-week, multinational, randomized, placebo-controlled prospective study of once-daily desloratadine at 5 mg in subjects with moderate-to-severe PER. Assessments included twice-daily symptom severity ratings (0 = none to 3 = severe; total and individual symptoms), sleep interference (morning [A.M.]), interference with activities of daily living (ADL; evening [P.M.]), the Rhinoconjunctivitis Quality of Life Questionnaire-Standardized version (baseline and days 29 and 85), and the Work Productivity and Activity Impairment-Allergy-Specific questionnaire (baseline and weekly). Pearson product-moment correlation statistics (r) were determined to assess correlations between symptom score improvements and QOL factors. All desloratadine-treated patients (n = 360) were included in this exploratory analysis. In the desloratadine-treated patients, all correlations tested were positive (all p < 0.0001). The highest coefficients were seen for the correlations between A.M./P.M. PRIOR total five-symptom score and interference with ADL (r = 0.72) and between A.M. NOW congestion and ADL interference (r = 0.69). Continuous daily treatment of moderate-to-severe PER with desloratadine at 5 mg/day significantly improved symptoms, which correlated positively, albeit moderately, with QOL benefits and reversal of functional impairments caused by PER. PMID:23676577

Bousquet, Jean; Zuberbier, Torsten; Canonica, G Walter; Fokkens, Wytske J; Gopalan, Gokul; Shekar, Tulin

2013-01-01

333

We establish correlations between equivalent widths of eight diffuse interstellar bands (DIBs), and examine their correlations with atomic hydrogen, molecular hydrogen, and E{sub B-V}. The DIBs are centered at {lambda}{lambda} 5780.5, 6204.5, 6283.8, 6196.0, 6613.6, 5705.1, 5797.1, and 5487.7, in decreasing order of Pearson's correlation coefficient with N(H) (here defined as the column density of neutral hydrogen), ranging from 0.96 to 0.82. We find the equivalent width (EW) of {lambda}5780.5 is better correlated with column densities of H than with E{sub B-V} or H{sub 2}, confirming earlier results based on smaller data sets. We show that the same is true for six of the seven other DIBs presented here. Despite this similarity, the eight strong DIBs chosen are not correlated well enough with each other to suggest they come from the same carrier. We further conclude that these eight DIBs are more likely to be associated with H than with H{sub 2}, and hence are not preferentially located in the densest, most UV shielded parts of interstellar clouds. We suggest that they arise from different molecules found in diffuse H regions with very little H{sub 2} (molecular fraction f < 0.01). Of the 133 stars with available data in our study, there are three with significantly weaker {lambda}5780.5 than our mean H-{lambda}5780.5 relationship, all of which are in regions of high radiation fields, as previously noted by Herbig. The correlations will be useful in deriving interstellar parameters when direct methods are not available. For instance, with care, the value of N(H) can be derived from W{sub {lambda}}(5780.5).

Friedman, Scott D.; Sonnentrucker, Paule [Space Telescope Science Institute, Baltimore, MD 21218 (United States); York, Donald G.; Hobbs, L. M. [Department of Astronomy and Astrophysics and the Enrico Fermi Institute, University of Chicago, Chicago, IL (United States); McCall, Benjamin J. [Departments of Chemistry, Astronomy, and Physics, University of Illinois at Urbana-Champaign, IL (United States); Dahlstrom, Julie [Department of Physics and Astronomy, Carthage College, Kenosha, WI (United States); Welty, Daniel E. [Department of Astronomy, University of Illinois at Urbana-Champaign, IL (United States); Drosback, Meredith M. [Department of Astronomy, University of Virginia, Charlottesville, VA (United States); Rachford, Brian L. [Department of Physics, Embry-Riddle Aeronautical University, Prescott, AZ (United States); Snow, Theodore P., E-mail: friedman@stsci.edu [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO (United States)

2011-01-20

334

Background Prospective measures of high knee abduction moment during landing identify female athletes at high risk for non-contact anterior cruciate ligament injury. Biomechanical laboratory measurements predict high knee abduction moment landing mechanics with high sensitivity (85%) and specificity (93%). The purpose of this study was to identify correlates to laboratory-based predictors of high knee abduction moment for use in a clinic-based anterior cruciate ligament injury risk prediction algorithm. The hypothesis was that clinically obtainable correlates derived from the highly predictive laboratory-based models would demonstrate high accuracy to determine high knee abduction moment status. Methods Female basketball and soccer players (N=744) were tested for anthropometrics, strength and landing biomechanics. Pearson correlation was used to identify clinically feasible correlates and logistic regression to obtain optimal models for high knee abduction moment prediction. Findings Clinical correlates to laboratory-based measures were identified and predicted high knee abduction moment status with 73% sensitivity and 70% specificity. The clinic-based prediction algorithm, including (Odds Ratio: 95% confidence interval) knee valgus motion (1.43:1.30–1.59 cm), knee flexion range of motion (.98:0.96–1.01 deg), body mass (1.04:1.02–1.06 kg), tibia length (1.38:1.25–1.52 cm) and quadriceps to hamstring ratio (1.70:1.06–2.70) predicted high knee abduction moment status with C statistic 0.81. Interpretation The combined correlates of increased knee valgus motion, knee flexion range of motion, body mass, tibia length and quadriceps to hamstrings ratio predict high knee abduction moment status in female athletes with high sensitivity and specificity.

Myer, Gregory D.; Ford, Kevin R.; Khoury, Jane; Succop, Paul; Hewett, Timothy E.

2010-01-01

335

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

336

Quantum discord and multipartite correlations

Recently, it was realized that quantum discord can be seen as the minimal amount of correlations which are lost when some local quantum operations are performed. Based on this formulation of quantum discord, we provide a systematical analysis of quantum and classical correlations present in both bipartite and multipartite quantum systems. As a natural result of this analysis, we introduce

Ma?gorzata Okrasa; Zbigniew Walczak

2011-01-01

337

Psychophysical correlations, synchronicity and meaning.

The dual-aspect framework which Jung developed with Wolfgang Pauli implies that psychophysical phenomena are neither reducible to physical processes nor to conscious mental activity. Rather, they constitute a radically novel kind of phenomena, deriving from correlations between the physical and the mental. In synchronistic events, a particular subclass of psychophysical phenomena, these correlations are explicated as experienced meaning. PMID:24673273

Atmanspacher, Harald

2014-04-01

338

Spurious Correlations in Mathematical Thinking.

ERIC Educational Resources Information Center

This study investigated whether undergraduate students encode spurious correlations in memory and exhibit them during the learning process leading to ineffectual problem solving. Findings suggested that even experienced students relied on surface-structure feature-algorithm correlations for solving new problems. Findings pose implications for…

Ben-Zeev, Talia; Star, Jon R.

2001-01-01

339

Correlation, Cost Risk, and Geometry.

National Technical Information Service (NTIS)

The geometric viewpoint identifies the choice of a correlation matrix for the simulation of cost risk with the pairwise choice of data vectors corresponding to the parameters used to obtain cost risk. The correlation coefficient is the cosine of the angle...

E. B. Dean

1992-01-01

340

A GENERAL CANONICAL CORRELATION INDEX

BECAUSE A CANONICAL CORRELATION IS THE CORRELATION BETWEEN 2 LINEAR COMPOSITES, IT PRESENTS SOME INTERPRETIVE PROBLEMS. NO MEASURE OF THE REDUNDANCY IN 1 SET OF VARIABLES, GIVEN ANOTHER SET OF VARIABLES, HAS BEEN AVAILABLE. A NONSYMMETRIC INDEX OF REDUNDANCY IS PROPOSED WHICH REPRESENTS THE AMOUNT OF PREDICTED VARIANCE IN A SET OF VARIABLES.

DOUGLAS STEWART; WILLIAM LOVE

1968-01-01

341

Continuum correlations in atomic ionization

Previous experimental and theoretical (e, 2e) studies are reviewed, with particular reference to the low energy region and to the difficulties that arise in the theoretical modelling when continuum correlations are important. Recent experiments are described in which the correlations in the atomic (e, 2e) ionization processes are explored in a novel way.

A. J. Murray; F. H. Read

1993-01-01

342

Drizzle correlations with giant nuclei

Giant nuclei (GN) concentrations (NGN) below RICO small cumulus clouds were substantially correlated with drizzle drop concentrations (Nd), especially at higher cloud altitudes. The NGN-Nd correlation coefficients (R) progressively increased with altitude whereas R for CCN concentrations with Nd were negative with mostly decreasing magnitudes at increasing altitudes. These results indicate that the positive influence of GN [or CCN with

James G. Hudson; Vandana Jha; Stephen Noble

2011-01-01

343

It is well accepted that atherosclerosis initiation and progression correlate positively with low and oscillating flow wall shear stresses (FSS). However, this mechanism cannot explain why advanced plaques continue to grow under elevated FSS conditions. In vivo magnetic resonance imaging (MRI)-based 2D/3D multi-component models with fluid-structure interactions (FSI, 3D only) for human carotid atherosclerotic plaques were introduced to quantify correlations between plaque progression measured by wall thickness increase (WTI) and plaque wall (structure) stress (PWS) conditions. A histologically validated multi-contrast MRI protocol was used to acquire multi-year in vivo MRI images. Our results using 2D models (200-700 data points/patient) indicated that 18 out of 21 patients studied showed significant negative correlation between WTI and PWS at time 2 (T2). The 95% confidence interval for the Pearson correlation coefficient is (-0.443,-0.246), p<0.0001. Our 3D FSI model supported the 2D correlation results and further indicated that combining both plaque structure stress and flow shear stress gave better approximation results (PWS, T2: R(2)=0.279; FSS, T1: R(2)=0.276; combining both: R(2)=0.637). These pilot studies suggest that both lower PWS and lower FSS may contribute to continued plaque progression and should be taken into consideration in future investigations of diseases related to atherosclerosis. PMID:18191138

Tang, Dalin; Yang, Chun; Mondal, Sayan; Liu, Fei; Canton, Gador; Hatsukami, Thomas S; Yuan, Chun

2008-01-01

344

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.

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

2014-01-01

345

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.

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

2014-01-01

346

Pupillary unrest correlates with arousal symptoms and motor signs in Parkinson disease

Background Arousal symptoms (e.g., sleepiness) are common in Parkinson disease and pupillary unrest (spontaneous changes in pupil diameter) is positively associated with sleepiness. We explored pupillary unrest in Parkinson disease. Methods Arousal symptoms (Epworth sleepiness scale and sleep/fatigue domain of the non-motor symptoms scale for Parkinson disease (NMS-sleep)) and pupillary unrest were assessed in 31 participants (14 PD, 17 controls). Effect sizes and t-tests compared Parkinson disease with control participants. Correlation coefficients were calculated among arousal symptoms, pupillary unrest and UPDRS-III. Linear regression was performed with arousal symptoms or pupillary unrest as outcome. Results Parkinson disease participants reported more arousal symptoms than controls. Pupillary unrest, arousal symptoms and UPDRS-III were positively correlated. The association between NMS-sleep score and pupillary unrest was higher in Parkinson disease versus controls, and higher in those with more Parkinsonian motor signs. UPRDS-III was positively associated with pupillary unrest. Conclusions Pupillary unrest correlates with motor and non-motor features associated with Lewy-related pathology, suggesting it may be a non-motor marker of progression in Parkinson disease.

Jain, Samay; Siegle, Greg J.; Gu, Chen; Moore, Charity G.; Ivanco, Larry S.; Studenski, Stephanie; Greenamyre, J. Timothy; Steinhauer, Stuart R.

2010-01-01

347

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

2013-10-18

348

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

349

Background Attention-deficit/hyperactivity disorder (ADHD) and substance use disorder are often comorbid in adults. The effects of ADHD treatment on comorbid alcohol use disorder have not been extensively studied. Objective To assess correlates of ADHD and alcohol use outcomes in ADHD with comorbid alcohol use disorders, via a post-hoc exploratory subgroup analysis of a previously conducted, randomized, double-blind, placebo controlled study of recently abstinent adults. Methods Adults who had ADHD and alcohol use disorders and were abstinent for 4–30 days were randomized to daily atomoxetine 25–100 mg (mean final dose=89.9 mg) or placebo for 12 weeks. Changes in ADHD symptoms from baseline to endpoint were assessed using the ADHD Investigator Symptom Rating Scale (AISRS) total score, alcohol use by the timeline followback method, and alcohol cravings by the Obsessive Compulsive Drinking Scale. Results Of 147 subjects receiving atomoxetine (n=72) or placebo (n=75) in the primary study, 80 (54%) completed 12 weeks (n=32 atomoxetine; n=48 placebo). Improvements in ADHD symptoms on the AISRS correlated significantly with decreases in alcohol cravings (Pearson’s r=0.28; 95% confidence interval [CI]=0.11–0.43; p=0.002), and the correlation was most notable with atomoxetine (r=0.29; CI [0.04 – 0.51]; p=0.023) rather than with placebo (r=0.24; CI [0.00–0.46]; p=0.055). On-treatment drinking levels correlated with AISRS scores (r=0.12; CI [0.05 –0.19]; p=0.001). Relapse to alcohol abuse significantly correlated with worse ADHD symptoms on 15 of 18 items of the AISRS in the placebo group (p<0.05 for each). Conclusions No baseline predictor (other than degree of sobriety) of alcohol use or ADHD outcomes emerged. ADHD symptom improvements correlated significantly with reductions in alcohol cravings, and relapse to alcohol abuse correlated significantly with worsening of most ADHD symptoms in the placebo group, but not in the atomoxetine group. This post-hoc subgroup analysis is of a hypothesis-generating nature, and the generalizability of the findings may be limited by exclusion of adults with common ADHD comorbidities from the base study. Further, prospective clinical trials in larger and more heterogeneous patient populations are warranted to confirm or reject these preliminary associations.

Wilens, Timothy E.; Adler, Lenard A.; Tanaka, Yoko; Xiao, Feng; D'Souza, Deborah N.; Gutkin, Stephen W.; Upadhyaya, Himanshu P.

2013-01-01

350

Background: Anaemia affects the body by decreased oxygen (O2) carrying capacity of the blood. There is growing evidence that anaemia contributes to cardiac disease and death. It causes O2 supply – demand myocardial mismatch causing myocardial ischemia. There is diversity of opinion available in literature on reports of electrocardiographic (ECG) changes in anaemia. Aim: To study the ECG changes in anemic population and to correlate ECG changes seen with increasing severity of anaemia. Materials and Methods: In hundred anemic adults, haemoglobin level and resting ECG were recorded. They were grouped according to haemoglobin level. ECG findings and varying severity of haemoglobin (Hb) level of each group were correlated using Pearson ’s co-relation co-efficient and association was calculated using Chi-square test. Results: ECG changes in patients with Hb level of 0-5gm% showed ST segment depression in 50-75%, T wave changes in 29-50% and Left Ventricular Hypertrophy (LVH) in 25-30% of patients. Less percentage of patients with 5-7gm% Hb showed such changes, and patients with 7-8gm% Hb, showed no changes. As the Hb level decreased there was more percentage of patients having tachycardia and ECG changes. There was a strong negative correlation between Hb level and tachycardia and ECG changes. Conclusion: Diagnosing anaemia in critical care can be supported by ECG changes like ST depression, T wave changes, with/without associated QRS abnormalities to avoid misdiagnosis and also as dramatic clinical and ECG recovery can be achieved with anaemia correction.

PK, Shashidhar; Herur, Anita; Chinagudi, Surekharani; Patil, Shailaja S; Ankad, Roopa B; Badami, Sukanya V

2014-01-01

351

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

352

t Tests and Intervals for Comparisons Suggested by the Data.

National Technical Information Service (NTIS)

The problem of testing a comparison c suggested by the data is first identified with the multiple comparisons problem for the class C of a priori equally plausible comparisons. A multiple comparisons dilemma is then illustrated by a simple example E empha...

D. B. Duncan

1975-01-01

353

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.

2014-01-01

354

The activation of host response proteins against parasitic infection is dependent on the coregulation of immune gene expression. The infection of commercially important silkworm Bombyx mori through endoparasite Exorista bombycis enhanced host-response gene expression in integument early in the infection and was lowered asymptotically. Principal component analysis (PCA) showed heterogeneity while explaining ?80 % variance among expression timings. PCA showed positive and negative correlation with gene expression and differentiated transcriptional timings, and revealed cross talk within the immune system. Pearson correlation analysis showed significant linear correlation (mean R (2)?=?>0.7; P?correlation of five gene pairs including PPAE-Spatzle pair (R (2)?=?0.9; P?correlation with the tyrosine level (R (2)?=?0.410; P?correlated with BmToll expression and negatively correlated with paralytical peptide expression, revealing polygenic influence. Caspase expression was tightly regulated by signal genes in control integument, whereas they were deregulated after infection. Switchover from linear to curvilinear correlation and the appearance of new gene correlations in parasitized integument revealed deviation from gene coregulation, leading to impaired immune responses, characterized by lowered gene expression and varied phenotypic consequences. PMID:24310719

Jayaram, Anitha; Pradeep, Appukuttan Nair R; Awasthi, Arvind K; Murthy, Geetha N; Ponnuvel, Kangayam M; Sasibhushan, Sirigineedi; Rao, Guruprasad C

2014-05-01

355

Correlation of triglyceride level with acute coronary syndrome.

The study was aimed to find out the correlation of serum triglyceride level with acute coronary syndrome. This cross sectional study was conducted in the department of cardiology, Mymensingh Medical College Hospital, from August 2009 to May 2010. Socio-demographic characteristics, smoking habit, hypertension, serum total cholesterol level, serum HDLc, Serum LDLc, TG level were important variable considered. A total number of 100 respondents consisted of 50 cases (patient) and 50 healthy persons (control). Investigations included ECG, cardiac enzyme (troponin I), FBS and lipid profile. The data were analyzed by computer with the help of SPSS. Chi-square Test, T-test & ANOVA test were used as test of significance. The mean level of TG in acute coronary syndrome (ACS) patients (cases) was 168.2±58.0 mg/dl and in control were 141.2±45.3 mg/dl. So serum TG level is significantly higher in patients with ACS (p=0.01). In multivariate regression analysis, there was a significant association of elevated TG with risk of ACS (relative risk) is the highest, compared with the lowest quarantile = 1.011; 95% confidence interval (CI = 1.002 - 1.020; P for trend = 0.01). The relation of TG level to HDLc was a strong predictor of ACS (RR in the highest) compared with lowest quarantile = 0.02; (95% CI = 0.003 - 0.173; P for trend <0.0001). The study revealed that high level of serum triglyceride is associated with ACS. Categorization of patients with ACS on the basis of TG level may be helpful for risk stratification and management. PMID:22314453

Islam, M Z; Faruque, M; Bari, M A; Islam, M S; Khan, M K; Khan, N A; Miah, A H; Alam, M K

2012-01-01

356

Correlation, Cost Risk, and Geometry

NASA Technical Reports Server (NTRS)

The geometric viewpoint identifies the choice of a correlation matrix for the simulation of cost risk with the pairwise choice of data vectors corresponding to the parameters used to obtain cost risk. The correlation coefficient is the cosine of the angle between the data vectors after translation to an origin at the mean and normalization for magnitude. Thus correlation is equivalent to expressing the data in terms of a non orthogonal basis. To understand the many resulting phenomena requires the use of the tensor concept of raising the index to transform the measured and observed covariant components into contravariant components before vector addition can be applied. The geometric viewpoint also demonstrates that correlation and covariance are geometric properties, as opposed to purely statistical properties, of the variates. Thus, variates from different distributions may be correlated, as desired, after selection from independent distributions. By determining the principal components of the correlation matrix, variates with the desired mean, magnitude, and correlation can be generated through linear transforms which include the eigenvalues and the eigenvectors of the correlation matrix. The conversion of the data to a non orthogonal basis uses a compound linear transformation which distorts or stretches the data space. Hence, the correlated data does not have the same properties as the uncorrelated data used to generate it. This phenomena is responsible for seemingly strange observations such as the fact that the marginal distributions of the correlated data can be quite different from the distributions used to generate the data. The joint effect of statistical distributions and correlation remains a fertile area for further research. In terms of application to cost estimating, the geometric approach demonstrates that the estimator must have data and must understand that data in order to properly choose the correlation matrix appropriate for a given estimate. There is a general feeling by employers and managers that the field of cost requires little technical or mathematical background. Contrary to that opinion, this paper demonstrates that a background in mathematics equivalent to that needed for typical engineering and scientific disciplines at the masters or doctorate level is appropriate within the field of cost risk.

Dean, Edwin B.

1992-01-01

357

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

358

Pairing correlations in transport theories.

National Technical Information Service (NTIS)

A transport equation is derived for non-equilibrium systems with pairing correlations. The derivation is carried out in the closed-time-path (Schwinger-Keldysh) formalism using a generalization of the Gorkov equations for contour ordered Green functions. ...

R. Fauser

1996-01-01

359

Multiple Correlation versus Multiple Regression.

ERIC Educational Resources Information Center

Describes differences between multiple correlation analysis (MCA) and multiple regression analysis (MRA), showing how these approaches involve different research questions and study designs, different inferential approaches, different analysis strategies, and different reported information. (SLD)

Huberty, Carl J.

2003-01-01

360

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; Josi?, Kresimir

2010-01-01

361

Attack Correlation Using Marked Information.

National Technical Information Service (NTIS)

Techniques are described for providing security to a protected network. Techniques are described for thwarting attempted network attacks using marked information. The attack correlation system provides marked information to computing devices that probe fo...

F. N. Adelstein H. Bar N. Proskourine P. Alla

2005-01-01

362

Product Correlations in Photofragment Dynamics,

National Technical Information Service (NTIS)

Correlations between either scalar or vector quantities measured in the study of photodissociation dynamics can serve to provide a very detailed picture of the dissociative event. This article discusses the use of Doppler profile and time of flight spectr...

G. E. Hall N. Sivakumar R. Ogorzalek G. Chawla H. P. Haerri

1986-01-01

363

Statistical Applets: Correlation and Regression

NSDL National Science Digital Library

Created for W.H. Freeman and Co., this applet is designed to help students see correlations in data and see how outliers can affect the correlation and least-squares line. Users can input their own data points and then try to fit a line to the data and see how the sum of squares changed. The user can then also see what the lest-square line is for that set of data.

2009-02-24

364

Correlated imaging through atmospheric turbulence

Correlated imaging through atmospheric turbulence is studied, and the analytical expressions describing turbulence effects on image resolution are derived. Compared with direct imaging, correlated imaging can reduce the influence of turbulence to a certain extent and reconstruct high-resolution images. The result is backed up by numerical simulations, in which turbulence-induced phase perturbations are simulated by random-phase screens inserted into propagation paths.

Zhang Pengli; Gong Wenlin; Shen Xia; Han Shensheng [Key Laboratory for Quantum Optics and Center for Cold Atom Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2010-09-15

365

Three Particle Correlations from Star

Two-particle correlations have shown modification to the away-side shape in central Au+Au collisions relative to pp, d+Au and peripheral Au+Au collisions. Different scenarios can explain this modification including: large angle gluon radiation, jets deflected by transverse flow, path length dependent energy loss, Cerenkov gluon radiation of fast moving particles, and conical flow generated by hydrodynamic Mach-cone shock-waves. Three-particle correlations have

Jason Glyndwr Ulery

2007-01-01

366

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

367

Background Physician advice is an important motivator for attempting to stop smoking. However, physicians' lack of intervention with smokers has only modestly improved in the last decade. Although the literature includes extensive research in the area of the smoking intervention practices of clinicians, few studies have focused on Hispanic physicians. The purpose of this study was to explore the correlates of tobacco cessation counseling practices among Hispanic physicians in the US. Methods Data were collected through a validated survey instrument among a cross-sectional sample of self-reported Hispanic physicians practicing in New Mexico, and who were members of the New Mexico Hispanic Medical Society in the year 2001. Domains of interest included counseling practices, self-efficacy, attitudes/responsibility, and knowledge/skills. Returned surveys were analyzed to obtain frequencies and descriptive statistics for each survey item. Other analyses included: bivariate Pearson's correlation, factorial ANOVAs, and multiple linear regressions. Results Respondents (n = 45) reported a low level of compliance with tobacco control guidelines and recommendations. Results indicate that physicians' familiarity with standard cessation protocols has a significant effect on their tobacco-related practices (r = .35, variance shared = 12%). Self-efficacy and gender were both significantly correlated to tobacco related practices (r = .42, variance shared = 17%). A significant correlation was also found between self-efficacy and knowledge/skills (r = .60, variance shared = 36%). Attitudes/responsibility was not significantly correlated with any of the other measures. Conclusion More resources should be dedicated to training Hispanic physicians in tobacco intervention. Training may facilitate practice by increasing knowledge, developing skills and, ultimately, enhancing feelings of self-efficacy.

Mas, Francisco G Soto; Balcazar, Hector G; Alberola, Julia Valderrama; Ed Hsu, Chiehwen

2008-01-01

368

Background The purpose of this study was to investigate the correlation between ocular perfusion pressure and ocular pulse amplitude in glaucoma, ocular hypertension, and normal eyes. Methods Ninety eyes from 90 patients were included. Thirty patients had been recently diagnosed with glaucoma and had no previous history of treatment for ocular hypotension, 30 had elevated intraocular pressure (IOP) without evidence of glaucoma, and 30 had normal IOP (<21 mmHg) with no detectable glaucomatous damage. Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), blood pressure measurement, pachymetry, Humphrey visual field, and routine ophthalmic examination was performed in each patient. Ocular perfusion pressure was calculated as the difference between mean arterial pressure and IOP. The ocular pulse amplitude was given by DCT. The Pearson correlation coefficient was used to compare the glaucomatous and ocular hypertensive groups, and comparisons with the normal IOP group were done using the Spearman’s rank correlation coefficient. Results Mean IOP by DCT was 22.7 ± 4.3 mmHg in the glaucoma group, 22.3 ± 2.8 mmHg in the ocular hypertension group, and 14.3 ± 1.6 mmHg in the control group. Mean IOP by GAT was 19.0 ± 5.1 mmHg for glaucoma, 22.4 ± 2.1 mmHg for ocular hypertension, and 12.9 ± 2.2 mmHg for controls. Mean ocular pulse amplitude was 3.4 ± 1.2 mmHg in the glaucoma group, 3.5 ± 1.2 mmHg in the ocular hypertension group, and 2.6 ± 0.9 mmHg in the control group. Mean ocular perfusion pressure was 46.3 ± 7.9 mmHg in the glaucoma group, 46.3 ± 7.9 mmHg in the ocular hypertension group, and 50.2 ± 7.0 mmHg in controls. No significant correlation between ocular perfusion pressure and ocular pulse amplitude was found in any of the groups (P = 0.865 and r = ?0.032, P = 0.403 and r = ?0.156, P = 0.082 and ? = ?0.307 for glaucoma, ocular hypertension, and normal eyes, respectively). Conclusion There is no significant correlation between ocular perfusion pressure and ocular pulse amplitude values in glaucoma, ocular hypertension, or normal eyes. IOP values measured by GAT correlate with those measured by DCT.

Figueiredo, Bruno P; Cronemberger, Sebastiao; Kanadani, Fabio N

2013-01-01

369

Background: The aim of the present study was to evaluate the relationship between the bone density of various regions of jaws and skeletal bones. Materials and Methods: A total of 110 patients with a mean age of 55.01 ± 10.77 years were selected for the purpose of the present descriptive study. Dual X-ray Energy Absorptiometry (DXA) was carried out to determine bone mineral density (BMD) of the femur and lumbar vertebrae. Then all the subjects underwent DXA of the jaw bones and BMD values were determined at four jaw regions. Data were analyzed by SPSS 16 statistical software, and the correlation between the various BMD values was determined by Pearson's correlation coefficient. Results: The results showed that 42.7% of females had normal BMD values in the femur, and in vertebrae, 20% were osteopenic and 37.3% suffered from osteoporosis, with statistically significant differences in the BMD values of the jaws between the three above-mentioned groups (P < 0.001). There was an increasing tendency toward osteopenia and osteoporosis with age. There was a positive correlation between BMD values of the femur and lumbar vertebrae and those of all the jaw regions under study (P < 0.005). There was a negative correlation (P < 0.01) between age and the BMD values of the femur, lumbar vertebrae and anterior maxilla. Conclusion: The bone density of the maxilla and mandible and presence of osteoporosis or osteopenia in these bones might reflect the same problem in skeletal bones.

Esfahanizadeh, Nasrin; Davaie, Sotoudeh; Rokn, A. R.; Daneshparvar, Hamid Reza; Bayat, Noushin; Khondi, Nasrin; Ajvadi, Sara; Ghandi, Mostafa

2013-01-01

370

Objective To determine the value of random urinary protein to creatinine ratio (UPCR) for diagnosis of proteinuria in pregnant women with preeclampsia. Preeclampsia is the most common complication of pregnancy and one of the main causes of maternal mortality. So, early diagnosis of preeclampsia is very important. Materials and methods In this cross-sectional study 66 pregnant women suspected preeclampsia at ?24 week of gestational age and BP ? 140/90 mm/Hg were checked by two urine samples of 10am and 4pm to determine random UPCR, as well as a 24-hour urine sample to evaluate 24-hour protein excretion. Results The result revealed that 74.2% of the studied population had significant proteinuria. There was a correlation between UPCR and 24-hour urine protein excretion. Pearson's correlation coefficient was 0.502 at 10am and 0.428 at 4pm. The best cutoff for the random urine protein to creatinine ratio at 10am was 0.470 with sensitivity and specificity equal to 87.5% and 84.2%, respectively. The best cutoff for the random UPCR at 4pm was 0.595 with sensitivity and specificity equal to 91.7% and 94.7%, respectively. Conclusion Result of 24-hour urine collection showing random UPCR is considered as an appropriate situated method for emergency time.

Moez, Nafiseh; Naghizadeh, Mohammad Mehdi; Abbasi, Maryam; Khodashenas, Zohreh

2013-01-01

371

Background The increase in cardiovascular events has necessitated the identification of possible predictors that can help in predicting atherogenicity. Objective The study sought to identify the anthropometric measures of adiposity that are associated with atherogenic risk in sedentary, non-obese, young male adults. Methods A cross-sectional design was used to recruit a purposive sample of 414 sedentary males in a university campus. Anthropometric measures of adiposity, lipid parameters, and atherogenic index of plasma (AIP) were assessed. Pearson correlation and stepwise multiple regression were used to analyze the data collected. Alpha level was set at p<0.05. Results There was a high risk of cardiovascular events (AIP=0.36±0.04 SD) among the participants. A significant correlation (p=0.000) was obtained between each of the anthropometric measures (except conicity index) and AIP. Body mass index, body adiposity index, and percent body fat were significant predictors accounting for 38.9, 3.1, and 2.2% of the variance due to AIP. Conclusions Sedentary status among young males is associated with high atherogenic risk in the presence of normal lipid and anthropometric parameters. Both central and general measures of adiposity predict less than half of the atherogenic risk in sedentary young males.

Ezeukwu, Antoninus O.; Agwubike, Elias O.

2014-01-01

372

Robustness of joint transform correlator versus Vander Lugt correlator

NASA Astrophysics Data System (ADS)

The robustness of the joint transform correlator (JTC) versus the VanderLugt correlator (VLC) are evaluated based on the transversal and the longitudinal misalignment. We show that the VLC is very sensitive to the transversal misalignment, while the JTC is not. Although the VLC performs better in terms of longitudinal alignment, the tolerable misalignment in recording the joint transform power spectrum is in the order of a millimeter, which can be easily adjusted in practice. In short, we conclude that the JTC is far more robust than the VLC.

Purwosumarto, Purwadi; Yu, Francis T.

1997-10-01

373

Abstract: Background: Both end-tidal carbon dioxide pressure (ETCO2) is used routinely as an indicator of arterial partial pressure of carbon dioxide (PaCO2) and thus adequacy of ventilation. Accurate determination of the PaCO2 level in neuroanesthesia is quite important because of its effect on cerebral blood flow and also hyperventilation is often used to reduce intracranial pressure in neurosurgical patients. This study was aimed to evaluate the relationship between ETCO2 and arterial PaCO2 in neurosurgical patients undergoing craniotomy to assess the predictive value of ETCO2 as an indicator of PaCO2 level. Methods: Forty-five consecutive adult patients with inclusion criteria, scheduled to undergo elective craniotomy surgery were enrolled in this prospective study. Measurements of PaCO2 and ETCO2 were performed at three different intervals: Time 1: 10 min after induction of general anesthesia; time 2: after cranium opening prior to dural incision; and at time 3: start of dural closure. All patients received the same anesthetic agent (propofol, sufentanil, atracurium, oxygen). Data were initially analyzed using Pearson’s Correlation to assess the relationship between PaCO2 and ETCO2 at different stages of the operation. A p-value (P) of less than 0.05 was considered significant. The agreement between the measures of CO2 was assessed using Bland-Altman method, where mean difference and average between PaCO2 and ETCO2 were calculated. The 95% confidence intervals for the lower and upper limits of agreement were presented. Results: A total of 44 patients, aged 18 to 65 years, ASA grades 1 and 2 were participated in the study. Mean difference, standard deviation and correlation coefficient of the parameters were calculated for three time periods. The values for PaCO2, ETCO2, (PaCO2- ETCO2), and correlation coefficient for 10 min after anesthetic induction, prior to dural incision, and start of dural closure were 35.4 ± 3.2, 32.1 ± 3.2, 3.8 ± 2.1, and 0.565, 36.2 ± 3.1, 32.6 ± 3.2,4.8 ± 3.1, and 0.574, and 36.7 ± 2.4, 33 ± 3.2,3.8 ± 2.3, and 0.627, respectively (p less than 0.01 for all analyses). The greatest mean difference occurred just prior to dural incision. The lowest mean difference was observed at 10 min post-anesthetic induction. Conclusions: To the present study was aimed to correlate between End-tidal and arterial carbon dioxide partial pressure in neurosurgical patients undergoing craniotomy. Findings of this study showed that ETCO2 consistently underestimates the value of PaCO2 during craniotomy indicating that ETCO2 value can be used instead of PaCO2. Keywords: End-tidal carbon dioxide pressure, Arterial partial pressure of carbon dioxide, Craniotomy

Hemmati, Naser; Zokaei, Abdol Hamid; Karbasforooshan, Ali

2012-01-01

374

Multivariable analysis, correlation, and prediction

NASA Astrophysics Data System (ADS)

Making best use of multi-point observations and sensor information to forecast future events in complex real time systems is a challenge which presents itself in many military and industrial problem domains. The first step in tackling these challenges is to analyze and understand the data. Depending on the algorithm used to forecast a future event, improvements to a prediction can be realized if one can first determine the nature and extent of variable correlations, and for the purposes of prediction, quantify the strength of the correlations of input variables to output variables. This is no easy task since sensor readings and operator logs are sometimes inconsistent and/or unreliable, some catastrophic failures can be almost impossible to predict, and time lags and leads in a given system may vary from one day to the next. Correlation analysis techniques can help us deal with some of these problems. They allow us to find out what variables may be strongly correlated to major events. After detecting where the strongest correlations exist, one must choose a model which can best predict the possible outcomes that could occur for a number of possible scenarios. The model must be tested and evaluated, and sometimes it is necessary to go back to the feature selection stage of the model design process and reevaluate the available sensory data and inputs. An industrial process example is adopted in this research to both highlight the issues that arise in complex systems and to demonstrate methods of addressing such issues.

Blowers, Misty; Iribarne, Jose; Scott, Gary

2009-05-01

375

Recirculating cross-correlation detector

A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.

Andrews, W.H. Jr.; Roberts, M.J.

1985-01-18

376

Enamel lesion parameter correlations between polychromatic micro-CT and TMR.

Transverse microradiography (TMR) is considered as the gold standard technique for the evaluation of enamel lesions. Micro-computed tomography (µCT) has the advantage of non-destructive measurements, but the beam-hardening effect with polychromatic x-rays is a major drawback. To date, no study has validated µCT against TMR. The objective of this study was to validate µCT measurements of enamel lesions under various x-ray conditions and software beam-hardening correction (BHC) against TMR. Human molars with natural white-spot lesions were scanned for 5 min by µCT at 100 kV in different conditions: 50 µA (0.5-mm Al filter), 165 µA (0.5-mm Al/0.3-mm Cu), and 200 µA (0.5-mm Al/0.4-mm Cu), with or without BHC. Grayscale values were converted into mineral density values using phantoms. Thin sections at the same positions were then prepared for TMR. Lesion depth (LD; µm) and mineral loss (?Z; vol%µm) were compared between µCT and TMR by Pearson's correlations. µCT measurements correlated well with TMR under all conditions (p < 0.001, r > 0.86 for LD and ?Z), except for 0.5-mm Al without BHC (p > 0.05). Even without BHC, combined Al/Cu filters successfully reduced the beam-hardening effect. µCT can be used as a non-destructive alternative to TMR with comparable parameters for the study of enamel lesions. PMID:22476867

Hamba, H; Nikaido, T; Sadr, A; Nakashima, S; Tagami, J

2012-06-01

377

Gene expression microarrays provide a powerful new tool for studying complex processes such as brain aging. However, inferences from microarray data are often hindered by multiple comparisons, small sample sizes, and uncertain relationships to functional endpoints. Here we sought gene expression correlates of aging-dependent cognitive decline, using statistical profiling of gene microarrays in well powered groups of young, mid-aged, and aged rats (n = 10 per group). Animals were trained on two memory tasks, and the hippocampal CA1 region of each was analyzed on an individual microarray (one chip per animal). Aging- and cognition-related genes were identified by testing each gene by ANOVA (for aging effects) and then by Pearson's test (correlating expression with memory). Genes identified by this algorithm were associated with several phenomena known to be aging-dependent, including inflammation, oxidative stress, altered protein processing, and decreased mitochondrial function, but also with multiple processes not previously linked to functional brain aging. These novel processes included downregulated early response signaling, biosynthesis and activity-regulated synaptogenesis, and upregulated myelin turnover, cholesterol synthesis, lipid and monoamine metabolism, iron utilization, structural reorganization, and intracellular Ca2+ release pathways. Multiple transcriptional regulators and cytokines also were identified. Although most gene expression changes began by mid-life, cognition was not clearly impaired until late life. Collectively, these results suggest a new integrative model of brain aging in which genomic alterations in early adulthood initiate interacting cascades of decreased signaling and synaptic plasticity in neurons, extracellular changes, and increased myelin turnover-fueled inflammation in glia that cumulatively induce aging-related cognitive impairment. PMID:12736351

Blalock, Eric M; Chen, Kuey-Chu; Sharrow, Keith; Herman, James P; Porter, Nada M; Foster, Thomas C; Landfield, Philip W

2003-05-01

378

Poor correlation between intracranial pressure and intraocular pressure by hand-held tonometry

Purpose The aim of this study is to provide data on the controversial issue of whether handheld measurements of intraocular pressure (IOP) are capable of accurately predicting elevated intracranial pressure (ICP) in patients undergoing lumbar puncture (LP). Methods All patients over the age of 18 years who underwent an LP in the emergency or neurological departments at the Tel Aviv Medical Center for any reason between October 2007 and July 2010 were eligible to participate in this prospective observational pilot study. IOP was measured with the Tono-Pen XL while patients were in the supine position before undergoing LP. ICP was measured in the lateral recumbent position. ICP and bilateral IOP were measured, and the mean and maximum values of IOP were calculated. The association between ICP and each one of the four IOP measures was evaluated by the Pearson correlation coefficient. Results Twenty-four patients (mean age 37.8 ± 15.8 years, ten males and 14 females) were enrolled. The reasons for their requiring an LP were headache (19/24 patients), evaluation for hemiparesis (2/24), cognitive deterioration (1/24), and seizures (2/24). Nine had elevated mean opening pressure (>20 cm H2O), six had an elevated mean IOP (>20 mmHg), and four of these six also had an elevated opening pressure. There was no significant correlation between the ICP measurements and any of the IOP measurements. Conclusion Handheld ocular tonometry has poor sensitivity and specificity for the prediction of increased ICP and is not an effective tool for screening for ICP in the ED or in the neurology department.

Golan, Shani; Kurtz, Shimon; Mezad-Koursh, Daphna; Waisbourd, Michael; Kesler, Anat; Halpern, Pinchas

2013-01-01

379

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

380

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.

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

2014-01-01

381

Reveal quantum correlation in complementary bases

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

382

Serum trace elements levels in preeclampsia and eclampsia: correlation with the pregnancy disorder.

Preeclampsia and eclampsia are fatal medical complications of pregnancy accounting for 20-80 % of increased maternal death in developing countries. Their aetiologies are still under investigation. Serum trace elements have been suggested to be involved in the pathogenesis of preeclampsia. Aim of this study was to address the correlation of serum trace elements with preeclampsia and eclampsia. It was a comparative cross-sectional study conducted on conveniently recruited 44 preeclampsia, 33 eclampsia and 27 normotensive pregnant patients. Atomic absorption spectrometry was employed to analyse serum concentrations of Ca, Mg, Cu, Zn and Fe. Data were analysed by Student's t test, one-way analysis of variance and multinomial logistic and binary regression analyses. p?correlations of Mg with Zn in eclampsia and Mg with Fe in preeclampsia and eclampsia were predicted. Significant changes in serum trace element levels were present in preeclampsia and eclampsia that may have a link with the pathogenesis of pregnancy disorder. PMID:23526144

Ahsan, Touhida; Banu, Salina; Nahar, Quamrun; Ahsan, Monira; Khan, Md Nazrul Islam; Islam, Sheikh Nazrul

2013-06-01

383

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.

Gopinath, Vellore Kannan; Anwar, Khurshid

2014-01-01

384

Correlated optical and isotopic nanoscopy

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

385

Quantum correlation via quantum coherence

NASA Astrophysics Data System (ADS)

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.

Yu, Chang-shui; Zhang, Yang; Zhao, Haiqing

2014-02-01

386

Softc: An Operational Software Correlator

NASA Technical Reports Server (NTRS)

Softc has been used operationally for spacecraft navigation at JPL for over 2 years and will be JPL's Mark 5 correlator next year. Softc was written to be as close to an ideal correlator as possible, making approximations only below 10(exp -13) seconds. The program can correlate real USB, real LSB, or complex I/Q data sampled with 1, 2, 4. or 8-bit resolution, and was developed with strong debugging tools that made final debugging relatively quick. Softc's algorithms and program structure are fully documented. Timing tests on a recent Intel CPU show Softc processes 8 lags of 1-bit sampled data at 10 MSamples/sec, independent of sample rate.

Lowe, Stephen T.

2004-01-01

387

Quantum correlation via quantum coherence

NASA Astrophysics Data System (ADS)

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.

Yu, Chang-shui; Zhang, Yang; Zhao, Haiqing

2014-06-01

388

Correlated electronic wave functions: Correlated and transcorrelated wave functions

The development of the transcorrelated Hamiltonian method (THM) by Boys and Handy seemed to imply that the determination of atomic and molecular wave functions and energies with full electronic correlation can be done with calculations which involve at worst only pseudo-six-dimensional integrals. We show that the THM equations of Boys and Handy are in fact only the first of a

M. W. C. Dharma-Wardana; François Grimaldi

1976-01-01

389

Long-range correlations in dusty plasmas

The correlations in dusty plasmas in the gaseous state is considered. It is shown that the long-ranged correlations of dust particles, contrary to usual matter, start to form in a weakly correlated state, leading finally to the formation of dust crystals and dust liquids with not strong but intermediate strength correlations. The physical mechanism leading to long-ranged correlations is the

V. N. Tsytovich; U. de Angelis; R. Bingham; D. Resendes

1997-01-01

390

Cultural correlates of youth suicide.

Youth suicide has risen in most developed nations over the past 50 years, especially among males, but the increase remains to be explained. Statistical analyses were used to examine associations between youth suicide rates in 11-21 mainly Western, developed nations and 32 socio-economic and cultural variables. The central hypothesis was that suicide rates would be correlated with various cultural measures of social attachment and integration, especially individualism. Socio-economic variables were included in the analysis to demonstrate the relative strength of the cultural associations. The study found a strong positive correlation between male youth suicide rates and subjective measures of health, optimism, and several indices of individualism, including personal freedom and control. Correlations between female youth suicide and individualism were smaller, attaining significance in only one instance. Male youth suicide and individualism were negatively correlated with older people's sense of parental duty. Correlations between suicide and other possibly relevant cultural variables--tolerance of suicide, belief in God and national pride--were not significant. The analysis of socio-economic variables yielded only one significant, but doubtful, correlation. The findings can be interpreted as supporting two very different hypotheses: that youth suicide represents "an island of misery in an ocean of happiness" or "the tip of an iceberg of suffering". In favouring the latter interpretation, and consistent with Durkheim's theories on suicide, it is argued that increased youth suicide reflects a failure of Western societies to provide appropriate sites or sources of social identity and attachment, and, conversely, a tendency to promote unrealistic or inappropriate expectations of individual freedom and autonomy. PMID:12406459

Eckersley, Richard; Dear, Keith

2002-12-01

391

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

392

Correlation-based biological networks

NASA Astrophysics Data System (ADS)

We construct a correlation-based biological network from a data set containing temporal expressions of 517 fibroblast tissue genes at transcription level. Four relevant and meaningful connected subgraphs of the network, namely: minimal spanning tree, maximal spanning tree, combined graph of minimal and maximal trees, and planar maximally filtered graph are extracted and the subgraphs' geometrical and topological properties are explored by computing relevant statistical quantities at local and global level. The results show that the subgraphs are extracting relevant information from the data set by retaining high correlation coeffcients. The design principle of the underlying biological functions is reflected in the topology of the graphs.

Song, Won-Min; Aste, Tomaso; Di Matteo, T.

2007-12-01

393

Correlation properties of loose groups

The two-point spatial correlation function for loose groups of galaxies is computed, using the recently compiled catalog of groups in the southern hemisphere. It is found that the correlation function for groups has a similar slope to that of galaxies but with a smaller amplitude, confirming an earlier result obtained from a similar analysis of the CfA group catalog. This implies that groups of galaxies are more randomly distributed than galaxies, which may be consistent with the predictions of Kashlinsky (1987) for a gravitational clustering scenario for the formation of large-scale structures. 21 refs.

Maia, M.A.G.; Da Costa, L.N. (Observatorio Nacional do Brasil, Rio de Janeiro (Brazil))

1990-02-01

394

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

395

Correlation of apparent diffusion coefficient with ki-67 proliferation index in grading meningioma.

OBJECTIVE. A noninvasive method to predict aggressiveness of high-grade meningiomas would be desirable because it would help anticipate tumor recurrence and improve tumor management and the treatment outcomes. The Ki-67 protein is a marker of tumor proliferation, and apparent diffusion coefficient (ADC) is related to tumor cellularity. Therefore, we sought to determine whether there is a statistically significant correlation between ADC and Ki-67 values in meningiomas and whether ADC values can differentiate various meningioma subtypes. MATERIALS AND METHODS. MRI examinations and histopathology of 68 surgically treated meningiomas were retrospectively reviewed. Mean ADC values were derived from diffusion imaging. Correlation coefficients were calculated for mean ADC and Ki-67 proliferation index values using linear regression. An independent unpaired Student t test was used to compare the ADC and Ki-67 proliferation index values from low-grade and more aggressive meningiomas. RESULTS. A statistically significant inverse correlation was found between ADC and Ki-67 proliferation index for low-grade and aggressive meningiomas (r(2) = -0.33, p = 0.0039). ADC values (± SD) of low-grade meningiomas (0.84 ± 0.14 × 10(-3) mm(2)/s) and aggressive (atypical or anaplastic) meningiomas (0.75 ± 0.03 × 10(-3) mm(2)/s) were significantly different (p = 0.0495). Using an ADC cutoff value of 0.70 × 10(-3) mm(2)/s, the sensitivity for diagnosing aggressive meningiomas was 29%, specificity was 94%, positive predictive value was 67%, and negative predictive value was 75%. CONCLUSION. ADC values correlate inversely with Ki-67 proliferation index and help differentiate low-grade from aggressive meningiomas. PMID:24848829

Tang, Yi; Dundamadappa, Sathish K; Thangasamy, Senthur; Flood, Thomas; Moser, Richard; Smith, Thomas; Cauley, Keith; Takhtani, Deepak

2014-06-01

396

We investigated the HE4 variant-specific expression patterns in various normal tissues as well as in normal and malignant endometrial tissues. The relationships between mRNA variants and age, body weight, or survival are analyzed. ICAT-labeled normal and endometrial cancer (EC) tissues were analyzed with multidimensional liquid chromatography followed by tandem mass spectrometry. Levels of HE4 mRNA variants were measured by real-time PCR. Mean mRNA levels were compared among 16 normal endometrial samples, 14 grade 1 and 14 grade 3 endometrioid EC, 15 papillary serous EC, and 14 normal human tissue samples. The relationship between levels of HE4 variants and EC patient characteristics was analyzed with the use of Pearson correlation test. We found that, although all five HE4 mRNA variants are detectable in normal tissue samples, their expression is highly tissue-specific, with epididymis, trachea, breast and endometrium containing the highest levels. HE4-V0, -V1, and -V3 are the most abundant variants in both normal and malignant tissues. All variants are significantly increased in both endometrioid and papillary serous EC, with higher levels observed in grade 3 endometrioid EC. In the EC group, HE4-V1, -V3, and -V4 levels inversely correlate with EC patient survival, whereas HE4-V0 levels positively correlate with age. HE4 variants exhibit tissue-specific expression, suggesting that each variant may exert distinct functions in normal and malignant cells. HE4 levels appear to correlate with EC patient survival in a variant-specific manner. When using HE4 as a biomarker for EC management, the effects of age should be considered. PMID:24252907

Jiang, Shi-Wen; Chen, Haibin; Dowdy, Sean; Fu, Alex; Attewell, John; Kalogera, Eleftheria; Drapkin, Ronny; Podratz, Karl; Broaddus, Russell; Li, Jinping

2013-01-01

397

EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems

NASA Astrophysics Data System (ADS)

Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed during SCES 2010. As we learned, past dogmas about strongly correlated materials and phenomena must be re-examined with an open and inquisitive mind. Invited speakers and respected leaders in the field were invited to contribute to this special issue and we have insisted that they present new data, ideas, or perspectives, as opposed to simply an overview of their past work. As with the conference, this special issue touches upon recent developments of strongly correlated electron systems in d-electron materials, such as Sr3Ru2O7, graphene, and the new Fe-based superconductors, but it is dominated by topics in f-electron compounds. Contributions reflect the growing appreciation for the influence of disorder and frustration, the need for organizing principles, as well as detailed investigations on particular materials of interest and, of course, new materials. As this special issue could not possibly capture the full breadth and depth that the conference had to offer, it is being published simultaneously with an issue of Journal of Physics: Conference Series containing 157 manuscripts in which all poster presenters at SCES 2010 were invited to contribute. Since this special issue grew out of the 2010 SCES conference, we take this opportunity to give thanks. This conference would not have been possible without the hard work of the SCES 2010 Program Committee, International and National Advisory Committees, Local Committee, and conference organizers, the New Mexico Consortium. We thank them as well as those organizations that generously provided financial support: ICAM-I2CAM, Quantum Design, Lakeshore, the National High Magnetic Field Laboratory and the Department of Energy National Laboratories at Argonne, Berkeley, Brookhaven, Los Alamos and Oak Ridge. Of course, we especially thank the participants for bringing new ideas and new results, without which SCES 2010 would not have been possible. Strongly correlated electron systems contents Spin-orbit coupling and k-dependent Zeeman splitting in strontium ruthenate Emil J Rozbicki, James F Annett, Jean-René Souquet an

Ronning, Filip; Batista, Cristian

2011-03-01

398

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

399

Background Careful observation of the longitudinal course of bipolar disorders is pivotal to finding optimal treatments and improving outcome. A useful tool is the daily prospective Life-Chart Method, developed by the National Institute of Mental Health. However, it remains unclear whether the patient version is as valid as the clinician version. Methods We compared the patient-rated version of the Lifechart (LC-self) with the Young-Mania-Rating Scale (YMRS), Inventory of Depressive Symptoms–Clinician version (IDS-C), and Clinical Global Impression–Bipolar version (CGI-BP) in 108 bipolar I and II patients who participated in the Naturalistic Follow-up Study (NFS) of the German centres of the Bipolar Collaborative Network (BCN; formerly Stanley Foundation Bipolar Network). For statistical evaluation, levels of severity of mood states on the Lifechart were transformed numerically and comparison with affective scales was performed using chi-square and t tests. For testing correlations Pearson´s coefficient was calculated. Results Ratings for depression of LC-self and total scores of IDS-C were found to be highly correlated (Pearson coefficient r?=??.718; p?correlation of ratings for mania with YMRS compared to LC-self were slightly less robust (Pearson coefficient r?=?.491; p?=?.001). These results were confirmed by good correlations between the CGI-BP IA (mania), IB (depression) and IC (overall mood state) and the LC-self ratings (Pearson coefficient r?=?.488, r?=?.721 and r?=?.65, respectively; all p?correlation and good concordance with standard cross sectional affective rating scales, suggesting that the LC-self is a valid and time and money saving alternative to the clinician-rated version which should be incorporated in future clinical research in bipolar disorder. Generalizability of the results is limited by the selection of highly motivated patients in specialized bipolar centres and by the open design of the study.

2014-01-01

400

NASA Technical Reports Server (NTRS)

Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.

Pasham, Dheeraj R.; Strohmayer, Tod E.

2013-01-01

401

Image Correlation on a Parallel Processor.

National Technical Information Service (NTIS)

Digital photogrammetry requires that conjugate imagery be located by image correlation. Image correlation involves many computations and can be the most time consuming part of the digital photogrammetry process. This report, in line and area correlations,...

D. L. Ackerman M. A. Crombie M. L. Powers

1976-01-01

402

Velocity correlations of galaxy clusters

We determine the velocity correlation function, pairwise peculiar velocity difference, and rms pairwise peculiar velocity dispersion of rich clusters of galaxies, as a function of pair separation, for three cosmological models: Omega = 1 and Omega = 0.3 cold dark matter (CDM), and Omega = 0.3 primeval baryonic isocurvature (PBI) models (all flat and Cosmic Background Explorer (COBE)-normalized). We find

Renyue Cen; Neta A. Bahcall; Mirt Gramann

1994-01-01

403

Personality correlates of driver stress

Summary-This paper reports four studies of personality and mood correlates of a validated questionnaire measure of predisposition to driver stress, the Driving Behaviour Inventory (DBI: Gulian, Matthews, Glendon, Davies & Debney, 1989a; Ergonomics, 32.585-602). The DBI measures a general factor of driver stress, plus five more specific dimensions. Study I (N = 159) found that general driver stress was positively

Gerald Matthews; Lisa Dorn; A. Ian Glendon

1991-01-01

404

Spearman Rank Order Correlation Coefficient

NSDL National Science Digital Library

This page will calculate r_s , the Spearman rank- order correlation coefficient, for a bivariate set of paired XY rankings. As the page opens, you will be prompted to enter the number of items for which there are paired rankings. If you are starting out with raw (unranked) data, the necessary rank-ordering will be performed automatically.

Lowry, Richard, 1940-

2008-06-25

405

Tetrachoric Correlation: A Permutation Alternative

ERIC Educational Resources Information Center

An exact permutation test is provided for the tetrachoric correlation coefficient. Comparisons with the conventional test employing Student's t distribution demonstrate the necessity of using the permutation approach for small sample sizes and/or disproportionate marginal frequency totals. (Contains 4 tables.)

Long, Michael A.; Berry, Kenneth J.; Mielke, Paul W., Jr.

2009-01-01

406

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

407

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

408

CCD Correlated Quadruple Sampling Processor.

National Technical Information Service (NTIS)

A correlated quadruple sampling processor for improved signal-to-noise ratio in the output of a charge-coupled device (CCD) is comprised of: (1) switching means for momentarily clamping a CCD signal line at a first reference level A before a CCD data puls...

S. D. Gaalema

1979-01-01

409

Biometric verification with correlation filters

Using biometrics for subject verification can significantly improve security over that of approaches based on passwords and personal identification numbers, both of which people tend to lose or forget. In biometric verification the system tries to match an input biometric (such as a fingerprint, face image, or iris image) to a stored biometric template. Thus correlation filter techniques are attractive

B. V. K. Vijaya Kumar; Marios Savvides; Chunyan Xie; Krithika Venkataramani; Jason Thornton; Abhijit Mahalanobis

2004-01-01

410

Correlated Tunneling in Hydrogen Bonds

NASA Astrophysics Data System (ADS)

We study the quantum nature of the protons participating in hydrogen bonds in several ice structures by analyzing the one particle density matrix. We find that in all cases, including ice Ih, the most common form of ice, and the high pressure phases, ice VIII, VII, and X, the system is ground-state dominated. However, while the dynamics is uncorrelated in the structures with standard asymmetric hydrogen bonds, such as ice Ih and VIII, local correlations among the protons characterize ice VII and, to a lesser extent, ice X in the so-called low barrier hydrogen bond regime. The correlations appear along the path to hydrogen bond symmetrization, when quantum fluctuations delocalize the proton on the two bond sides. The correlations derive from a strong requirement for local charge neutrality that favors concerted motion along the bonds. The resulting behavior deviates substantially from mean field theory, which would predict in ice VII coherent tunneling of the proton between the two bond sides, thereby causing an ionization catastrophe. Due to the correlations, the quantum state of the proton is entangled.

Lin, Lin; Morrone, Joseph A.; Car, Roberto

2011-10-01

411

Correlation Algorithm: the Conceptual Framework.

National Technical Information Service (NTIS)

The lack of a utilitarian solution to the frame-to-frame correlation problem poses insurmountable difficulties for the successful passive observation of a collection of co-moving, nearly co-located objects. This is exactly the task faced in a scenario wit...

L. G. Taff

1988-01-01

412

Pairing correlations in exotic nuclei

NASA Astrophysics Data System (ADS)

The BCS and HFB theories which can accommodate the pairing correlations in the ground states of atomic nuclei are presented. As an application of the pairing theories, we investigate the spatial extension of weakly bound Ne and C isotopes by taking into account the pairing correlation with the Hartree-Fock-Bogoliubov (HFB) method and a 3-body model, respectively. We show that the odd-even staggering in the reaction cross sections of 30,31,32Ne and 14,15,16C are successfully reproduced, and thus the staggering can be attributed to the unique role of pairing correlations in nuclei far from the stability line. A correlation between a one-neutron separation energy and the anti-halo effect is demonstrated for s- and p-waves using the HFB wave functions. We also propose effective density-dependent pairing interactions which reproduce both the neutron-neutron (nn) scattering length at zero density and the neutron pairing gap in uniform matter. Then, we apply these interactions to study pairing gaps in semi-magic finite nuclei, such as Ca, Ni, Sn and Pb isotopic chains.

Sagawa, H.; Hagino, K.

2013-02-01

413

Normalized correlation for pattern recognition

The normalization of the correlation filter response effects intensity invariance. We discuss the implications of a normalization based on the Cauchy--Schwarz inequality for the discrimination problem. It is shown that normalized phase-only and synthetic discriminant functions do not provide the discrimination\\/recognition obtained with the classical matched filter.

Fred M. Dickey; Louis A. Romero

1991-01-01

414

Correlation effects and bound states

Bound states in a simple quark model that are due to correlation effects are analyzed. The confining properties of this model in meson (quark-antiquark and diquark) channels manifest themselves at any quark momenta, and an extra potential field may only enhance the confining effect.

Zinovjev, G. M. [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine); Molodtsov, S. V., E-mail: molodtsov@itep.ru [Joint Institute for Nuclear Research (Russian Federation)

2012-11-15

415

Denoising seismic noise cross correlations

Seismic noise cross correlations have become a novel way of probing the elastic structure of the Earth without relying on an often highly nonuniform and sporadic distribution of earthquakes. By circumventing this restriction, one can determine the elastic Green's function between any two points where instruments exist. For tomography, this will allow for a larger distribution of crossing paths and

A. M. Baig; M. Campillo; F. Brenguier

2009-01-01

416

Optimized cross correlation waveforms for first order correlation loops

NASA Astrophysics Data System (ADS)

The phase-locked loop (PLL) architecture is studied extensively. It is demonstrated that PLLs are optimal structures in terms of minimizing steady-state mean square tracking error (MSE) at high SNRs. A closely related device, the delay-locked loop (DLL), is useful for estimating the time delay, or phase, of nonsinusoidal signals. Both PLLs and DLLs fall into the general class known as correlation-loop architectures. It is shown that the steady-state mean square tracking error of first-order correlation loops is minimized by varying the locally generated cross correlation function produced by the voltage controlled oscillator. This analysis assists in the design of modified first-order DLLS used for pseudonoise code synchronization in direct sequence spread-spectrum receivers. The optimization is performed for periodic, but otherwise arbitrary, transmitted signals, for systems operating at arbitrary SNR. The optimal reference waveform is produced by passing a replica of the transmitted signal through a linear time-invariant filter, G(f). This filter introduces a 90 deg phase shift at all frequencies. The amplitude response of G(f) is a function of the SNR. To find this optimal response, it is necessary to solve a multidimensional, nonlinear integral equation. Due to the complexity of the expression, a closed-form solution could not be found. It is possible to gain valuable insight by analyzing the asymptotic properties of the solution. The expression was also evaluated using numerical methods. The results are consistent with the asymptotic solutions.

Kosbar, K. L.

417

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

418

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.

Takahashi, Mao

2014-01-01

419

Background. Angiogenesis is a complex process involved in both growth and progression of several human and animal tumours. Tryptase is a serin protease stored in mast cells granules, which plays a role in tumour angiogenesis. Mast cells (MCs) can release tryptase following c-Kit receptor (c-KitR) activation. Method. In a series of 25 gastric cancer patients with stage T3N2-3M0 (by AJCC for Gastric Cancer 7th Edition), immunohistochemistry and image analysis methods were employed to evaluate in the tumour tissue the correlation between the number of mast cells positive to tryptase (MCPT), c-KitR expressing cells (c-KitR-EC), and microvascular density (MVD). Results. Data demonstrated a positive correlation between MCPT, c-KitR-EC, and MVD to each other. In tumour tissue the mean number of MCPT was 15, the mean number of c-KitR-EC was 20, and the mean number of MVD was 20. The Pearson test correlating MCPT and MVD, c-KitR-EC and MVD was significantly (r = 0.64, P = 0.001; r = 0.66, P = 0.041, resp.). Conclusion. In this pilot study, we suggest that MCPT and c-KitR-EC play a role in gastric cancer angiogenesis, so we think that several c-KitR or tryptase inhibitors such as gabexate mesilate and nafamostat mesilate might be evaluated in clinical trials as a new antiangiogenetic approach. PMID:24348541

Ammendola, Michele; Sacco, Rosario; Sammarco, Giuseppe; Donato, Giuseppe; Zuccalà, Valeria; Romano, Roberto; Luposella, Maria; Patruno, Rosa; Vallicelli, Carlo; Verdecchia, Giorgio Maria; Cavaliere, Davide; Montemurro, Severino; Ranieri, Girolamo

2013-01-01

420

Background. Angiogenesis is a complex process involved in both growth and progression of several human and animal tumours. Tryptase is a serin protease stored in mast cells granules, which plays a role in tumour angiogenesis. Mast cells (MCs) can release tryptase following c-Kit receptor (c-KitR) activation. Method. In a series of 25 gastric cancer patients with stage T3N2-3M0 (by AJCC for Gastric Cancer 7th Edition), immunohistochemistry and image analysis methods were employed to evaluate in the tumour tissue the correlation between the number of mast cells positive to tryptase (MCPT), c-KitR expressing cells (c-KitR-EC), and microvascular density (MVD). Results. Data demonstrated a positive correlation between MCPT, c-KitR-EC, and MVD to each other. In tumour tissue the mean number of MCPT was 15, the mean number of c-KitR-EC was 20, and the mean number of MVD was 20. The Pearson test correlating MCPT and MVD, c-KitR-EC and MVD was significantly (r = 0.64, P = 0.001; r = 0.66, P = 0.041, resp.). Conclusion. In this pilot study, we suggest that MCPT and c-KitR-EC play a role in gastric cancer angiogenesis, so we think that several c-KitR or tryptase inhibitors such as gabexate mesilate and nafamostat mesilate might be evaluated in clinical trials as a new antiangiogenetic approach.

Sacco, Rosario; Sammarco, Giuseppe; Donato, Giuseppe; Zuccala, Valeria; Romano, Roberto; Luposella, Maria; Patruno, Rosa; Vallicelli, Carlo; Verdecchia, Giorgio Maria; Cavaliere, Davide; Montemurro, Severino; Ranieri, Girolamo

2013-01-01

421

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?m(2). 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

Shiba, Tomoaki; Takahashi, Mao; Maeno, Takatoshi

2014-01-01

422

Are general quantum correlations monogamous?

Quantum entanglement and quantum nonlocality are known to exhibit monogamy; that is, they obey strong constraints on how they can be distributed among multipartite systems. Quantum correlations that comprise and go beyond entanglement are quantified by, e.g., quantum discord. It was observed recently that for some states quantum discord is not monogamous. We prove, in general, that any measure of correlations that is monogamous for all states and satisfies reasonable basic properties must vanish for all separable states: only entanglement measures can be strictly monogamous. Monogamy of other than entanglement measures can still be satisfied for special, restricted cases: we prove that the geometric measure of discord satisfies the monogamy inequality on all pure states of three qubits. PMID:23006154

Streltsov, Alexander; Adesso, Gerardo; Piani, Marco; Bruss, Dagmar

2012-08-01

423

Ultraviolet divergences in cosmological correlations

NASA Astrophysics Data System (ADS)

A method is developed for dealing with ultraviolet divergences in calculations of cosmological correlations, which does not depend on dimensional regularization. An extended version of the WKB approximation is used to analyze the divergences in these calculations, and these divergences are controlled by the introduction of Pauli-Villars regulator fields. This approach is illustrated in the theory of a scalar field with arbitrary self-interactions in a fixed flat-space Robertson-Walker metric with arbitrary scale factor a(t). Explicit formulas are given for the counterterms needed to cancel all dependence on the regulator properties, and an explicit prescription is given for calculating finite regulator-independent correlation functions. The possibility of infrared divergences in this theory is briefly considered.

Weinberg, Steven

2011-03-01

424

A correlated nickelate synaptic transistor.

Inspired by biological neural systems, neuromorphic devices may open up new computing paradigms to explore cognition, learning and limits of parallel computation. Here we report the demonstration of a synaptic transistor with SmNiO?, a correlated electron system with insulator-metal transition temperature at 130°C in bulk form. Non-volatile resistance and synaptic multilevel analogue states are demonstrated by control over composition in ionic liquid-gated devices on silicon platforms. The extent of the resistance modulation can be dramatically controlled by the film microstructure. By simulating the time difference between postneuron and preneuron spikes as the input parameter of a gate bias voltage pulse, synaptic spike-timing-dependent plasticity learning behaviour is realized. The extreme sensitivity of electrical properties to defects in correlated oxides may make them a particularly suitable class of materials to realize artificial biological circuits that can be operated at and above room temperature and seamlessly integrated into conventional electronic circuits. PMID:24177330

Shi, Jian; Ha, Sieu D; Zhou, You; Schoofs, Frank; Ramanathan, Shriram

2013-01-01

425

A correlated nickelate synaptic transistor

NASA Astrophysics Data System (ADS)

Inspired by biological neural systems, neuromorphic devices may open up new computing paradigms to explore cognition, learning and limits of parallel computation. Here we report the demonstration of a synaptic transistor with SmNiO3, a correlated electron system with insulator-metal transition temperature at 130°C in bulk form. Non-volatile resistance and synaptic multilevel analogue states are demonstrated by control over composition in ionic liquid-gated devices on silicon platforms. The extent of the resistance modulation can be dramatically controlled by the film microstructure. By simulating the time difference between postneuron and preneuron spikes as the input parameter of a gate bias voltage pulse, synaptic spike-timing-dependent plasticity learning behaviour is realized. The extreme sensitivity of electrical properties to defects in correlated oxides may make them a particularly suitable class of materials to realize artificial biological circuits that can be operated at and above room temperature and seamlessly integrated into conventional electronic circuits.

Shi, Jian; Ha, Sieu D.; Zhou, You; Schoofs, Frank; Ramanathan, Shriram

2013-10-01

426

Electroclinical correlation in neonatal seizures.

A dissociation between clinical and electroencephalographic phenomena is often observable in neonatal seizures. This finding raises important questions, including those related to the management of these patients. Another characteristic of neonatal convulsions is represented by their increased tendency towards status epilepticus. In order to examine the electroclinical correlation and its possible relationship to the occurrence of status epilepticus, recorded video-electroencephalograms of 17 newborns were submitted to detailed analysis. Time of onset, duration and other characteristics of all clinical and electrical events were noted. Five degrees of correlation were observed, from constant concurrence to complete dissociation. Examining the role of different parameters, it was observed that the incidence of electric discharges related significantly to the occurrence of electroclinical dissociation. PMID:10726833

Biagioni, E; Ferrari, F; Boldrini, A; Roversi, M F; Cioni, G

1998-01-01

427

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

428

Velocity correlations of galaxy clusters

NASA Technical Reports Server (NTRS)

We determine the velocity correlation function, pairwise peculiar velocity difference, and rms pairwise peculiar velocity dispersion of rich clusters of galaxies, as a function of pair separation, for three cosmological models: Omega = 1 and Omega = 0.3 cold dark matter (CDM), and Omega = 0.3 primeval baryonic isocurvature (PBI) models (all flat and Cosmic Background Explorer (COBE)-normalized). We find that close cluster pairs, with separation r is less than or equal to 10/h Mpc, exhibit strong attractive peculiar velocities in all models; the cluster pairwise velocities depend sensitively on the model. The mean pairwise attractive velocity of clusters on 5/h Mpc scale ranges from approximately 1700 km/s for Omega = 1 CDM to approximately 1000 km/s for PBI to approximately 700 km/s for Omega = 0.3 CDM. The small-scale pairwise velocities depend also on cluster mass: richer, more massive clusters exhibit stronger attractive velocities than less massive clusters. On large scales, from approximately 20 to 200/h Mpc, the cluster peculiar velocities are increasingly dominated by bulk and random motions; they are independent of cluster mass. The cluster velocity correlation function is negative on small scales for Omega = 1 and Omega = 0.3 CDM, indicating strong pairwise motion relative to bulk motion on small scales; PBI exhibits relatively larger bulk motions. The cluster velocity correlation function is positive on very large scales, from r approximately 10/h Mpc to r approximately 200/h Mpc, for all models. These positive correlations, which decrease monotonically with scale, indicate significant bulk motions of clusters up to approximately 200/h Mpc. The strong dependence of the cluster velocity functions on models, especially at small separations, makes them useful tools in constraining cosmological models when compared with observations.

Cen, Renyue; Bahcall, Neta A.; Gramann, Mirt

1994-01-01

429

The Planet-Metallicity Correlation

The tendency of planets to be found preferentially around metal-rich stars is now well established. This correlation gives strong support for most planets being formed by a core accretion scenario. The situation for planets around stars with sub-solar metallicity is, however, much less clear. In the metallicity range -0.8<[Fe\\/H]<-0.2, the overwhelming majority of stars belong to the thin-disk, but most

William D. Cochran; M. Endl; P. J. MacQueen; S. Barnes

2008-01-01

430

Coal combustion chemistry correlation aspects

This book provides fundamental guidelines to reducing the combustion problems that inorganic impurity compounds cause in coal-fired electricity-generating plants. The compounds treated are those of eight major-abundance metal and semimetal elements - silcon, aluminum, iron, calcium, potassium, magnesium, titanium, and sodium. The book employs a combustion chemistry approach, together with a methodology that relates empirical correlations to the effects of

Badin

1984-01-01

431

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

432

CCD correlators for auditory models

Surface-channel charge-coupled devices (CCDs) provide a mechanism for analog signal delay that can be built using an ordinary double-poly CMOS digital process, such as offered by Orbit through MOSIS. This technique has been applied to implement the correlation processing needed in auditory models of the sort proposed by J.C.R. Licklider (1951) for monaural pitch perception and sound separation. The resulting

Richard F. Lyon

1991-01-01

433

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.

434

Electron correlation energies in atoms

NASA Astrophysics Data System (ADS)

This dissertation is a study of electron correlation energies Ec in atoms. (1) Accurate values of E c are computed for isoelectronic sequences of "Coulomb-Hooke" atoms with varying mixtures of Coulombic and Hooke character. (2) Coupled-cluster calculations in carefully designed basis sets are combined with fully converged second-order Moller-Plesset perturbation theory (MP2) computations to obtain fairly accurate, non-relativistic Ec values for the 12 closed-shell atoms from Ar to Rn. The complete basis-set (CBS) limits of MP2 energies are obtained for open-shell atoms by computations in very large basis sets combined with a knowledge of the MP2/CBS limit for the next larger closed-shell atom with the same valence shell structure. Then higher-order correlation corrections are found by coupled-cluster calculations using basis sets that are not quite as large. The method is validated for the open-shell atoms from Al to Cl and then applied to get E c values, probably accurate to 3%, for the 4th-period open-shell atoms: K, Sc-Cu, and Ga-Br. (3) The results show that, contrary to quantum chemical folklore, MP2 overestimates |Ec| for atoms beyond Fe. Spin-component scaling arguments are used to provide a simple explanation for this overestimation. (4) Eleven non-relativistic density functionals, including some of the most widely-used ones, are tested on their ability to predict non-relativistic, electron correlation energies for atoms and their cations. They all lead to relatively poor predictions for the heavier atoms. Several novel, few-parameter, density functionals for the correlation energy are developed heuristically. Four new functionals lead to improved predictions for the 4th-period atoms without unreasonably compromising accuracy for the lighter atoms. (5) Simple models describing the variation of E c with atomic number are developed.

McCarthy, Shane Patrick

435

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

436

Wolfram syndrome: a clinicopathologic correlation

Wolfram syndrome or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness) is a neurodegenerative disorder characterized by diabetes mellitus and optic atrophy as well as diabetes insipidus and deafness in many cases. We report the post-mortem neuropathologic findings of a patient with Wolfram syndrome and correlate them with his clinical presentation. In the hypothalamus, neurons in the paraventricular and supraoptic nuclei were markedly decreased and minimal neurohypophyseal tissue remained in the pituitary. The pontine base and inferior olivary nucleus showed gross shrinkage and neuron loss, while the cerebellum was relatively unaffected. The visual system had moderate to marked loss of retinal ganglion neurons, commensurate loss of myelinated axons in the optic nerve, chiasm and tract, and neuron loss in the lateral geniculate nucleus but preservation of the primary visual cortex. The patient’s inner ear showed loss of the organ of Corti in the basal turn of the cochleae and mild focal atrophy of the stria vascularis. These findings correlated well with the patient’s high-frequency hearing loss. The pathologic findings correlated closely with the patient’s clinical symptoms and further support the concept of Wolfram syndrome as a neurodegenerative disorder. Our findings extend prior neuropathologic reports of Wolfram syndrome by providing contributions to our understanding of eye, inner ear and olivopontine pathology in this disease.

Merchant, Saumil N.; Adams, Joe C.; Joseph, Jeffrey T.

2009-01-01

437

A Robust Correlation Measure for Correspondence Estimation

A median correlation for the estimation of corresponding points in stereovision is proposed. It is based on the normalised correlation coefficient using the median instead of the mean. Its performance appears to be superior than conventional correlation specially in depth discontinuities image areas. This conclusion is derived from an empirical evaluation in which the proposed correlation is compared with the

Maria F. Trujillo; Ebroul Izquierdo

2004-01-01

438

Degree of correlation inside a financial market

I present an empirical study of the correlations observed between pairs of time series of stock prices in the New York Stock Exchange. I verify that various degrees of correlations or anti-correlations are present inside a financial market and I study the time evolution of these correlations. I briefly discuss how these empirical observations might be consistent with the well

Rosario Nunzio Mantegna

1997-01-01

439

Measurement of Correlation-Enhanced Collision Rates

We measure the perpendicular-to-parallel collision rate {nu}{sub perpendicular||} in laser-cooled magnetized ion plasmas, spanning the uncorrelated to correlated regimes. In correlated regimes, we measure collision rates consistent with the 'Salpeter correlation enhancement' of roughly exp({gamma}), for correlation parameters {gamma} < or approx. 4. This enhancement also applies to fusion in dense plasmas such as stars.

Anderegg, F.; Dubin, D. H. E.; O'Neil, T. M.; Driscoll, C. F. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

2009-05-08

440

Background The 6?min walk test (6MWT) is increasingly used as an outcome measure in interstitial lung disease (ILD). Aim To evaluate the usefulness of the 6MWT in a cohort of patients with ILD secondary to systemic sclerosis (SSc) and to correlate with established physiological parameters. Methods 163 patients with SSc?ILD were recruited for a multicentre, randomised, double?blind clinical trial. Available data at protocol screening included repeated 6MWTs, pulmonary function testing with diffusing capacity, Doppler echocardiography and high?resolution computed tomography of the thorax. Borg Dyspnoea Index was evaluated before and after 6MWT. Results Mean (standard deviation (SD)) distance walked during walk test 1 was 396.6 (84.55)?m compared with 399.5 (86.28)?m at walk test 2. The within?subject, intertest correlation as determined by Pearson's correlation coefficient testing was 0.95 (p<0.001). However, only weak correlations of 6MWT with percentage forced vital capacity and the Borg Dyspnoea Index were observed, and no correlation was observed with percentage diffusing capacity. Conclusion These data confirm the high reproducibility of the 6MWT in patients with SSc?ILD and therefore the validity of the test in this cohort. The lack of correlation of 6MWT with standard physiological parameters of ILD suggests a multifactorial basis for limited exercise capacity in patients with SSc and calls into question the utility of the 6MWT as a measure of outcome in future studies on SSc?ILD.

Buch, M H; Denton, C P; Furst, D E; Guillevin, L; Rubin, L J; Wells, A U; Matucci-Cerinic, M; Riemekasten, G; Emery, P; Chadha-Boreham, H; Charef, P; Roux, S; Black, C M; Seibold, J R

2007-01-01