Robustness of Two Formulas to Correct Pearson Correlation for Restriction of Range
ERIC Educational Resources Information Center
tran, minh
2011-01-01
Many research studies involving Pearson correlations are conducted in settings where one of the two variables has a restricted range in the sample. For example, this situation occurs when tests are used for selecting candidates for employment or university admission. Often after selection, there is interest in correlating the selection variable,…
Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu
2014-01-01
This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment. PMID:25393286
Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu
2014-01-01
This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment.
Wang, Luman; Mo, Qiaochu; Wang, Jianxin
2015-01-01
Most current gene coexpression databases support the analysis for linear correlation of gene pairs, but not nonlinear correlation of them, which hinders precisely evaluating the gene-gene coexpression strengths. Here, we report a new database, MIrExpress, which takes advantage of the information theory, as well as the Pearson linear correlation method, to measure the linear correlation, nonlinear correlation, and their hybrid of cell-specific gene coexpressions in immune cells. For a given gene pair or probe set pair input by web users, both mutual information (MI) and Pearson correlation coefficient (r) are calculated, and several corresponding values are reported to reflect their coexpression correlation nature, including MI and r values, their respective rank orderings, their rank comparison, and their hybrid correlation value. Furthermore, for a given gene, the top 10 most relevant genes to it are displayed with the MI, r, or their hybrid perspective, respectively. Currently, the database totally includes 16 human cell groups, involving 20,283 human genes. The expression data and the calculated correlation results from the database are interactively accessible on the web page and can be implemented for other related applications and researches. PMID:26881263
ERIC Educational Resources Information Center
Vos, Pauline
2009-01-01
When studying correlations, how do the three bivariate correlation coefficients between three variables relate? After transforming Pearson's correlation coefficient r into a Euclidean distance, undergraduate students can tackle this problem using their secondary school knowledge of geometry (Pythagoras' theorem and similarity of triangles).…
de Winter, Joost C F; Gosling, Samuel D; Potter, Jeff
2016-09-01
The Pearson product-moment correlation coefficient () and the Spearman rank correlation coefficient () are widely used in psychological research. We compare and on 3 criteria: variability, bias with respect to the population value, and robustness to an outlier. Using simulations across low (N = 5) to high (N = 1,000) sample sizes we show that, for normally distributed variables, and have similar expected values but is more variable, especially when the correlation is strong. However, when the variables have high kurtosis, is more variable than . Next, we conducted a sampling study of a psychometric dataset featuring symmetrically distributed data with light tails, and of 2 Likert-type survey datasets, 1 with light-tailed and the other with heavy-tailed distributions. Consistent with the simulations, had lower variability than in the psychometric dataset. In the survey datasets with heavy-tailed variables in particular, had lower variability than , and often corresponded more accurately to the population Pearson correlation coefficient () than did. The simulations and the sampling studies showed that variability in terms of standard deviations can be reduced by about 20% by choosing instead of . In comparison, increasing the sample size by a factor of 2 results in a 41% reduction of the standard deviations of and . In conclusion, is suitable for light-tailed distributions, whereas is preferable when variables feature heavy-tailed distributions or when outliers are present, as is often the case in psychological research. (PsycINFO Database Record
Technology Transfer Automated Retrieval System (TEKTRAN)
Measurements of texture properties related to tenderness at different locations within deboned broiler breast fillets have been used to validate techniques for texture analysis and establish correlations between different texture evaluation methods. However, it has been demonstrated that meat text...
ERIC Educational Resources Information Center
Zimmerman, Donald W.
2012-01-01
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…
The Use of Time Series Analysis and t Tests with Serially Correlated Data Tests.
ERIC Educational Resources Information Center
Nicolich, Mark J.; Weinstein, Carol S.
1981-01-01
Results of three methods of analysis applied to simulated autocorrelated data sets with an intervention point (varying in autocorrelation degree, variance of error term, and magnitude of intervention effect) are compared and presented. The three methods are: t tests; maximum likelihood Box-Jenkins (ARIMA); and Bayesian Box Jenkins. (Author/AEF)
Mohamed Salleh, Faridah Hani; Arif, Shereena Mohd; Zainudin, Suhaila; Firdaus-Raih, Mohd
2015-12-01
A gene regulatory network (GRN) is a large and complex network consisting of interacting elements that, over time, affect each other's state. The dynamics of complex gene regulatory processes are difficult to understand using intuitive approaches alone. To overcome this problem, we propose an algorithm for inferring the regulatory interactions from knock-out data using a Gaussian model combines with Pearson Correlation Coefficient (PCC). There are several problems relating to GRN construction that have been outlined in this paper. We demonstrated the ability of our proposed method to (1) predict the presence of regulatory interactions between genes, (2) their directionality and (3) their states (activation or suppression). The algorithm was applied to network sizes of 10 and 50 genes from DREAM3 datasets and network sizes of 10 from DREAM4 datasets. The predicted networks were evaluated based on AUROC and AUPR. We discovered that high false positive values were generated by our GRN prediction methods because the indirect regulations have been wrongly predicted as true relationships. We achieved satisfactory results as the majority of sub-networks achieved AUROC values above 0.5.
Duthie, R. B.
1979-01-01
This lecture covers some subjects of direct concern to the medical profession contained within the Pearson Report. Each injury group was examined by the Royal Commission, both here and abroad, particular attention being paid to the relationship between tort and social security. By consensus it was proposed that in the majority of fields no-fault compensations should be extended but that the tort system should continue to have a role. Recommendations were also put forward that no damages should be permitted for non-pecuniary loss during the first 3 months and that the full value of the social security benefits should be deductible from all tort damages. Damages for permanent injury or death should be index-linked periodic payments. A new no-fault compensation scheme for road accidents was described as well as a new disabled children's allowance of 4 pounds per week with a mobility allowance at the lower age of 2 years. Medical injury was examined carefully, but it was decided that negligence liability should continue unchanged, with the proviso that the no-fault compensation schemes in New Zealand and in Sweden should be followed. These two schemes have therefore been described in some detail. PMID:159014
Pearson's Functions to Describe FSW Weld Geometry
Lacombe, D.; Coupard, D.; Tcherniaeff, S.; Girot, F.; Gutierrez-Orrantia, M. E.
2011-01-17
Friction stir welding (FSW) is a relatively new joining technique particularly for aluminium alloys that are difficult to fusion weld. In this study, the geometry of the weld has been investigated and modelled using Pearson's functions. It has been demonstrated that the Pearson's parameters (mean, standard deviation, skewness, kurtosis and geometric constant) can be used to characterize the weld geometry and the tensile strength of the weld assembly. Pearson's parameters and process parameters are strongly correlated allowing to define a control process procedure for FSW assemblies which make radiographic or ultrasonic controls unnecessary. Finally, an optimisation using a Generalized Gradient Method allows to determine the geometry of the weld which maximises the assembly tensile strength.
Minati, Ludovico; Zacà, Domenico; D'Incerti, Ludovico; Jovicich, Jorge
2014-09-01
An outstanding issue in graph-based analysis of resting-state functional MRI is choice of network nodes. Individual consideration of entire brain voxels may represent a less biased approach than parcellating the cortex according to pre-determined atlases, but entails establishing connectedness for 1(9)-1(11) links, with often prohibitive computational cost. Using a representative Human Connectome Project dataset, we show that, following appropriate time-series normalization, it may be possible to accelerate connectivity determination replacing Pearson correlation with l1-norm. Even though the adjacency matrices derived from correlation coefficients and l1-norms are not identical, their similarity is high. Further, we describe and provide in full an example vector hardware implementation of l1-norm on an array of 4096 zero instruction-set processors. Calculation times <1000 s are attainable, removing the major deterrent to voxel-based resting-sate network mapping and revealing fine-grained node degree heterogeneity. L1-norm should be given consideration as a substitute for correlation in very high-density resting-state functional connectivity analyses. PMID:25023958
Parental Socio-Economic Status as Correlate of Child Labour in Ile-Ife, Nigeria
ERIC Educational Resources Information Center
Elegbeleye, O. S.; Olasupo, M. O.
2012-01-01
This study investigated the relationship between parental socio-economic status and child labour practices in Ile-Ife, Nigeria. The study employed survey method to gather data from 200 parents which constituted the study population. Pearson Product Moment Correlation and t-test statistics were used for the data analyses. The outcome of the study…
T test as a parametric statistic.
Kim, Tae Kyun
2015-12-01
In statistic tests, the probability distribution of the statistics is important. When samples are drawn from population N (µ, σ(2)) with a sample size of n, the distribution of the sample mean X̄ should be a normal distribution N (µ, σ(2)/n). Under the null hypothesis µ = µ0, the distribution of statistics [Formula: see text] should be standardized as a normal distribution. When the variance of the population is not known, replacement with the sample variance s (2) is possible. In this case, the statistics [Formula: see text] follows a t distribution (n-1 degrees of freedom). An independent-group t test can be carried out for a comparison of means between two independent groups, with a paired t test for paired data. As the t test is a parametric test, samples should meet certain preconditions, such as normality, equal variances and independence.
Bayesian Estimation Supersedes the "t" Test
ERIC Educational Resources Information Center
Kruschke, John K.
2013-01-01
Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional "t" tests) when certainty in the estimate is…
16. TYPE F, BUILDING #516732 PEARSON ROAD, INTERIOR, SECOND FLOOR, ...
16. TYPE F, BUILDING #516-732 PEARSON ROAD, INTERIOR, SECOND FLOOR, HALLWAY, NORTHWEST VIEW. - Wright-Patterson Air Force Base, Brick Officers' Quarters, Types E & F, Area A, Dayton, Montgomery County, OH
9. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
9. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING EAST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
10. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
10. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING NORTHEAST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
14. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
14. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING NORTH (INTERIOR) - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
15. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
15. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING NORTH (INTERIOR) - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
11. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
11. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING SOUTHWEST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
16. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
16. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 LOOKING NORTH (INTERIOR) - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
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
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
Plotting Formula for Pearson Type III Distribution Considering Historical Information.
ERIC Educational Resources Information Center
Nguyen, Van Thanh-Van; In-na, Nophadol
1992-01-01
Proposes a plotting position formula for the Pearson type III distribution in the analysis of historical flood information. Presents results of a numerical example using actual flood data to confirm the appropriateness of the plotting formula. (24 references) (MDH)
Karl Pearson and eugenics: personal opinions and scientific rigor.
Delzell, Darcie A P; Poliak, Cathy D
2013-09-01
The influence of personal opinions and biases on scientific conclusions is a threat to the advancement of knowledge. Expertise and experience does not render one immune to this temptation. In this work, one of the founding fathers of statistics, Karl Pearson, is used as an illustration of how even the most talented among us can produce misleading results when inferences are made without caution or reference to potential bias and other analysis limitations. A study performed by Pearson on British Jewish schoolchildren is examined in light of ethical and professional statistical practice. The methodology used and inferences made by Pearson and his coauthor are sometimes questionable and offer insight into how Pearson's support of eugenics and his own British nationalism could have potentially influenced his often careless and far-fetched inferences. A short background into Pearson's work and beliefs is provided, along with an in-depth examination of the authors' overall experimental design and statistical practices. In addition, portions of the study regarding intelligence and tuberculosis are discussed in more detail, along with historical reactions to their work. PMID:23179067
Karl Pearson and eugenics: personal opinions and scientific rigor.
Delzell, Darcie A P; Poliak, Cathy D
2013-09-01
The influence of personal opinions and biases on scientific conclusions is a threat to the advancement of knowledge. Expertise and experience does not render one immune to this temptation. In this work, one of the founding fathers of statistics, Karl Pearson, is used as an illustration of how even the most talented among us can produce misleading results when inferences are made without caution or reference to potential bias and other analysis limitations. A study performed by Pearson on British Jewish schoolchildren is examined in light of ethical and professional statistical practice. The methodology used and inferences made by Pearson and his coauthor are sometimes questionable and offer insight into how Pearson's support of eugenics and his own British nationalism could have potentially influenced his often careless and far-fetched inferences. A short background into Pearson's work and beliefs is provided, along with an in-depth examination of the authors' overall experimental design and statistical practices. In addition, portions of the study regarding intelligence and tuberculosis are discussed in more detail, along with historical reactions to their work.
19. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
19. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 GATE TO NORTH DOOR OF MEETINGHOUSE LOOKING EAST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
12. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
12. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 FIRST FLOOR LOOKING SOUTHEAST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
13. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 ...
13. Historic American Buildings Survey Elmer R. Pearson, Photographer 1969 FIRST FLOOR LOOKING SOUTHEAST - Sabbathday Lake Shaker Community Meetinghouse, West of State Route 26, South of North Raymond Road, northwest edge of church family area, Sabbathday Lake Village, Cumberland County, ME
Commercialising Comparison: Pearson Puts the TLC in Soft Capitalism
ERIC Educational Resources Information Center
Hogan, Anna; Sellar, Sam; Lingard, Bob
2016-01-01
This paper provides a critical policy analysis of "The Learning Curve" (TLC) (2012), an initiative developed by the multinational edu-business, Pearson, in conjunction with the Economist Intelligence Unit. "TLC" exemplifies the commercialising of comparison and the efforts of edu-businesses to strategically position themselves…
The "Student" of the Student's t-Test.
ERIC Educational Resources Information Center
Page, Brian R.
1995-01-01
Presents a brief life history of William Sealy Gosset, the "Student" of Student's t-test. Reviews some basic statistics and describes Student's t-test of statistical hypothesis. Contains 11 references. (JRH)
Pearson syndrome in a Diamond-Blackfan anemia cohort.
Alter, Blanche P
2014-07-17
In this issue of Blood, Gagne et al describe a cohort of 362 patients clinically classified as having Diamond-Blackfan anemia (DBA), in which 175 (48%) were found to have mutations and deletions in ribosomal protein genes or GATA1, and 8 of the remaining patients (2.2% overall) had mitochondrial gene deletions consistent with Pearson marrow-pancreas syndrome (PS). The authors propose that all patients with presumptive DBA should be tested for mitochondrial DNA (mtDNA) deletion during their initial genetic evaluation.
Neyman Pearson detection of K-distributed random variables
NASA Astrophysics Data System (ADS)
Tucker, J. Derek; Azimi-Sadjadi, Mahmood R.
2010-04-01
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.
Mitochondrial DNA deletion in a patient with combined features of Leigh and Pearson syndromes
Blok, R.B.; Thorburn, D.R.; Danks, D.M.
1994-09-01
We describe a heteroplasmic 4237 bp mitochondrial DNA (mtDNA) deletion in an 11 year old girl who has suffered from progressive illness since birth. She has some features of Leigh syndrome (global developmental delay with regression, brainstem dysfunction and lactic acidosis), together with other features suggestive of Pearson syndrome (history of pancytopenia and failure to thrive). The deletion was present at a level greater than 50% in skeletal muscle, but barely detectable in skin fibroblasts following Southern blot analysis, and only observed in blood following PCR analysis. The deletion spanned nt 9498 to nt 13734, and was flanked by a 12 bp direct repeat. Genes for cytochrome c oxidase subunit III, NADH dehydrogenase subunits 3, 4L, 4 and 5, and tRNAs for glycine, arginine, histidine, serine({sup AGY}) and leucine({sup CUN}) were deleted. Southern blotting also revealed an altered Apa I restriction site which was shown by sequence analysis to be caused by G{r_arrow}A nucleotide substitution at nt 1462 in the 12S rRNA gene. This was presumed to be a polymorphism. No abnormalities of mitochondrial ultrastructure, distribution or of respiratory chain enzyme complexes I-IV in skeletal muscle were observed. Mitochondrial disorders with clinical features overlapping more than one syndrome have been reported previously. This case further demonstrates the difficulty in correlating observed clinical features with a specific mitochondrial DNA mutation.
Sample size determination for a t test given a t value from a previous study: A FORTRAN 77 program.
Gillett, R
2001-11-01
When uncertain about the magnitude of an effect, researchers commonly substitute in the standard sample-size-determination formula an estimate of effect size derived from a previous experiment. A problem with this approach is that the traditional sample-size-determination formula was not designed to deal with the uncertainty inherent in an effect-size estimate. Consequently, estimate-substitution in the traditional sample-size-determination formula can lead to a substantial loss of power. A method of sample-size determination designed to handle uncertainty in effect-size estimates is described. The procedure uses the t value and sample size from a previous study, which might be a pilot study or a related study in the same area, to establish a distribution of probable effect sizes. The sample size to be employed in the new study is that which supplies an expected power of the desired amount over the distribution of probable effect sizes. A FORTRAN 77 program is presented that permits swift calculation of sample size for a variety of t tests, including independent t tests, related t tests, t tests of correlation coefficients, and t tests of multiple regression b coefficients.
Parameter estimation for the Pearson type 3 distribution using order statistics
NASA Astrophysics Data System (ADS)
Rocky Durrans, S.
1992-05-01
The Pearson type 3 distribution and its relatives, the log Pearson type 3 and gamma family of distributions, are among the most widely applied in the field of hydrology. Parameter estimation for these distributions has been accomplished using the method of moments, the methods of mixed moments and generalized moments, and the methods of maximum likelihood and maximum entropy. This study evaluates yet another estimation approach, which is based on the use of the properties of an extreme-order statistic. Based on the hypothesis that the population is distributed as Pearson type 3, this estimation approach yields both parameter and 100-year quantile estimators that have lower biases and variances than those of the method of moments approach as recommended by the US Water Resources Council.
"Describing our whole experience": the statistical philosophies of W. F. R. Weldon and Karl Pearson.
Pence, Charles H
2011-12-01
There are two motivations commonly ascribed to historical actors for taking up statistics: to reduce complicated data to a mean value (e.g., Quetelet), and to take account of diversity (e.g., Galton). Different motivations will, it is assumed, lead to different methodological decisions in the practice of the statistical sciences. Karl Pearson and W. F. R. Weldon are generally seen as following directly in Galton's footsteps. I argue for two related theses in light of this standard interpretation, based on a reading of several sources in which Weldon, independently of Pearson, reflects on his own motivations. First, while Pearson does approach statistics from this "Galtonian" perspective, he is, consistent with his positivist philosophy of science, utilizing statistics to simplify the highly variable data of biology. Weldon, on the other hand, is brought to statistics by a rich empiricism and a desire to preserve the diversity of biological data. Secondly, we have here a counterexample to the claim that divergence in motivation will lead to a corresponding separation in methodology. Pearson and Weldon, despite embracing biometry for different reasons, settled on precisely the same set of statistical tools for the investigation of evolution. PMID:22035721
The Beta Distribution,moment method, Karl Pearson and R.A.Fisher
Bowman, Kimiko o
2007-01-01
Simulation studies provide four moment approximating distributions to each of the four parameters of a beta distribution (Pearson Type I). Two of the parameters refer to origin and scale, two to shape (skewness and kurtosis). Type I random number generator is checked out, and the stability of moments of random samples of size n over cycles; particular attention is paid to shape parameter moments. In Type I region of validity (referred to skewness and kurtosis), moment methods become unstable in the neighborhood of Type III ({chi}{sup 2}) line, and ultimately abort. Thus extremely large variances and large higher moments arise. We probe the cause of this phenomenon. Simulation studies are turned to since alternative power series methods are forbiddingly complicated. However, use is made of the delta method to provide asymptotic variances of the estimators, and asymptotic variances of percentage points of the basic distribution. An account of work on the subject by K. Pearson, some of it a century ago, is given. In particular an important paper by Pearson and Filon provides some estimates of probable errors of moment parameter estimators such as the basic distribution parameters, the mode, the skewness and others. The heated controversy between Pearson and Fisher is considered.
Magnello, M E
1998-01-01
Long-standing claims have been made for nearly the entire twentieth century that the biometrician, Karl Pearson, and colleague, W. F. R. Weldon, rejected Mendelism as a theory of inheritance. It is shown that at the end of the nineteenth century Pearson considered various theories of inheritance (including Francis Galton's law of ancestral heredity for characters underpinned by continuous variation), and by 1904 he 'accepted the fundamental idea of Mendel' as a theory of inheritance for discontinuous variation. Moreover, in 1909, he suggested a synthesis of biometry and Mendelism. Despite the many attempts made by a number of geneticists (including R. A. Fisher in 1936) to use Pearson's chi-square (X2, P) goodness-of-fit test on Mendel's data, which produced results that were 'too good to be true', Weldon reached the same conclusion in 1902, but his results were never acknowledged. The geneticist and arch-rival of the biometricians, Williams Bateson, was instead exceptionally critical of this work and interpreted this as Weldon's rejection of Mendelism. Whilst scholarship on Mendel, by historians of science in the last 18 years, has led to a balanced perspective of Mendel, it is suggested that a better balanced and more rounded view of the hereditarian-statistical work of Pearson, Weldon, and the biometricians is long overdue. PMID:11619806
ERIC Educational Resources Information Center
Tosolt, Brandelyn; Love, Bettina L.
2011-01-01
Multicultural education is a term with a variety of definitions growing from a number of different disciplines. These authors conducted a content analysis of the Pearson reading program "Good Habits, Great Readers" for grades four and five. The qualitative approach of content analysis allowed researchers to examine text "through the…
Fusarium Osteomyelitis in a Patient With Pearson Syndrome: Case Report and Review of the Literature
Hiebert, Rachael M.; Welliver, Robert C.; Yu, Zhongxin
2016-01-01
Fusarium species are ubiquitous fungi causing a wide array of infections, including invasive disease in the immunosuppressed. We present a fusarium bone infection in a child with Pearson syndrome and review the literature. Ten cases of fusarium osteomyelitis were reported in the past 40 years, and we review the treatments. PMID:27757410
ERIC Educational Resources Information Center
Pae, Hye K.
2012-01-01
The aim of this study was to apply Rasch modeling to an examination of the psychometric properties of the "Pearson Test of English Academic" (PTE Academic). Analyzed were 140 test-takers' scores derived from the PTE Academic database. The mean age of the participants was 26.45 (SD = 5.82), ranging from 17 to 46. Conformity of the participants'…
Magnello, M E
1998-01-01
Long-standing claims have been made for nearly the entire twentieth century that the biometrician, Karl Pearson, and colleague, W. F. R. Weldon, rejected Mendelism as a theory of inheritance. It is shown that at the end of the nineteenth century Pearson considered various theories of inheritance (including Francis Galton's law of ancestral heredity for characters underpinned by continuous variation), and by 1904 he 'accepted the fundamental idea of Mendel' as a theory of inheritance for discontinuous variation. Moreover, in 1909, he suggested a synthesis of biometry and Mendelism. Despite the many attempts made by a number of geneticists (including R. A. Fisher in 1936) to use Pearson's chi-square (X2, P) goodness-of-fit test on Mendel's data, which produced results that were 'too good to be true', Weldon reached the same conclusion in 1902, but his results were never acknowledged. The geneticist and arch-rival of the biometricians, Williams Bateson, was instead exceptionally critical of this work and interpreted this as Weldon's rejection of Mendelism. Whilst scholarship on Mendel, by historians of science in the last 18 years, has led to a balanced perspective of Mendel, it is suggested that a better balanced and more rounded view of the hereditarian-statistical work of Pearson, Weldon, and the biometricians is long overdue.
Choosing the Best Correction Formula for the Pearson r[superscript 2] Effect Size
ERIC Educational Resources Information Center
Skidmore, Susan Troncoso; Thompson, Bruce
2011-01-01
In the present Monte Carlo simulation study, the authors compared bias and precision of 7 sampling error corrections to the Pearson r[superscript 2] under 6 x 3 x 6 conditions (i.e., population ρ 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;…
Is the Pearson r[squared] Biased, and if So, What Is the Best Correction Formula?
ERIC Educational Resources Information Center
Wang, Zhongmiao; Thompson, Bruce
2007-01-01
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…
Sassi, Radhouane Haj; Dardouri, Wajdi; Yahmed, Mohamed Haj; Gmada, Nabil; Mahfoudhi, Mohamed Elhedi; Gharbi, Zied
2009-09-01
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.
Using the Student's "t"-Test with Extremely Small Sample Sizes
ERIC Educational Resources Information Center
de Winter, J. C .F.
2013-01-01
Researchers occasionally have to work with an extremely small sample size, defined herein as "N" less than or equal to 5. Some methodologists have cautioned against using the "t"-test when the sample size is extremely small, whereas others have suggested that using the "t"-test is feasible in such a case. The present…
On the Relative Power of the Paired Samples t Test and Wilcoxon's Signed-Ranks Test.
ERIC Educational Resources Information Center
Blair, R. Clifford; Higgins, James J.
Monte Carlo methods were employed to assess the relative power of the paired samples t test and Wilcoxon's signed-ranks test under ten population shapes. Results of the study indicated that: (1) each of the two statistics was more powerful than the other in given situations; (2) the power advantages of the t test under normal theory were small;…
When "t"-Tests or Wilcoxon-Mann-Whitney Tests Won't Do
ERIC Educational Resources Information Center
McElduff, Fiona; Cortina-Borja, Mario; Chan, Shun-Kai; Wade, Angie
2010-01-01
"t"-Tests are widely used by researchers to compare the average values of a numeric outcome between two groups. If there are doubts about the suitability of the data for the requirements of a "t"-test, most notably the distribution being non-normal, the Wilcoxon-Mann-Whitney test may be used instead. However, although often applied, both tests may…
Computers and the severely physically handicapped: a pilot project at Pearson Hospital.
Stride, B
1982-10-01
Computers are a rapidly developing technology affecting the lives of everyone, including those in the handicapped population. Major revolutions are occurring in the technology available for physically and mentally handicapped persons. This article presents the results and findings of a pilot computer project that was implemented at Pearson Hospital. The use of the computer, adapted to persons of severe physical disability, as a typewriter, a programming device, and as a word processor is explained. The success of the program, and the difficulties experienced in making it run, are presented, along with suggestions for setting up and implementing computer projects in other institutions. An assessment form for potential computer users is presented.
Pearson-type goodness-of-fit test with bootstrap maximum likelihood estimation.
Yin, Guosheng; Ma, Yanyuan
2013-01-01
The Pearson test statistic is constructed by partitioning the data into bins and computing the difference between the observed and expected counts in these bins. If the maximum likelihood estimator (MLE) of the original data is used, the statistic generally does not follow a chi-squared distribution or any explicit distribution. We propose a bootstrap-based modification of the Pearson test statistic to recover the chi-squared distribution. We compute the observed and expected counts in the partitioned bins by using the MLE obtained from a bootstrap sample. This bootstrap-sample MLE adjusts exactly the right amount of randomness to the test statistic, and recovers the chi-squared distribution. The bootstrap chi-squared test is easy to implement, as it only requires fitting exactly the same model to the bootstrap data to obtain the corresponding MLE, and then constructs the bin counts based on the original data. We examine the test size and power of the new model diagnostic procedure using simulation studies and illustrate it with a real data set.
Fisher, Neyman-Pearson or NHST? A tutorial for teaching data testing
Perezgonzalez, Jose D.
2015-01-01
Despite frequent calls for the overhaul of null hypothesis significance testing (NHST), this controversial procedure remains ubiquitous in behavioral, social and biomedical teaching and research. Little change seems possible once the procedure becomes well ingrained in the minds and current practice of researchers; thus, the optimal opportunity for such change is at the time the procedure is taught, be this at undergraduate or at postgraduate levels. This paper presents a tutorial for the teaching of data testing procedures, often referred to as hypothesis testing theories. The first procedure introduced is Fisher's approach to data testing—tests of significance; the second is Neyman-Pearson's approach—tests of acceptance; the final procedure is the incongruent combination of the previous two theories into the current approach—NSHT. For those researchers sticking with the latter, two compromise solutions on how to improve NHST conclude the tutorial. PMID:25784889
Fisher, Neyman-Pearson or NHST? A tutorial for teaching data testing.
Perezgonzalez, Jose D
2015-01-01
Despite frequent calls for the overhaul of null hypothesis significance testing (NHST), this controversial procedure remains ubiquitous in behavioral, social and biomedical teaching and research. Little change seems possible once the procedure becomes well ingrained in the minds and current practice of researchers; thus, the optimal opportunity for such change is at the time the procedure is taught, be this at undergraduate or at postgraduate levels. This paper presents a tutorial for the teaching of data testing procedures, often referred to as hypothesis testing theories. The first procedure introduced is Fisher's approach to data testing-tests of significance; the second is Neyman-Pearson's approach-tests of acceptance; the final procedure is the incongruent combination of the previous two theories into the current approach-NSHT. For those researchers sticking with the latter, two compromise solutions on how to improve NHST conclude the tutorial. PMID:25784889
Pearson marrow pancreas syndrome in patients suspected to have Diamond-Blackfan anemia.
Gagne, Katelyn E; Ghazvinian, Roxanne; Yuan, Daniel; Zon, Rebecca L; Storm, Kelsie; Mazur-Popinska, Magdalena; Andolina, Laura; Bubala, Halina; Golebiowska, Sydonia; Higman, Meghan A; Kalwak, Krzysztof; Kurre, Peter; Matysiak, Michal; Niewiadomska, Edyta; Pels, Salley; Petruzzi, Mary Jane; Pobudejska-Pieniazek, Aneta; Szczepanski, Tomasz; Fleming, Mark D; Gazda, Hanna T; Agarwal, Suneet
2014-07-17
Pearson marrow pancreas syndrome (PS) is a multisystem disorder caused by mitochondrial DNA (mtDNA) deletions. Diamond-Blackfan anemia (DBA) is a congenital hypoproliferative anemia in which mutations in ribosomal protein genes and GATA1 have been implicated. Both syndromes share several features including early onset of severe anemia, variable nonhematologic manifestations, sporadic genetic occurrence, and occasional spontaneous hematologic improvement. Because of the overlapping features and relative rarity of PS, we hypothesized that some patients in whom the leading clinical diagnosis is DBA actually have PS. Here, we evaluated patient DNA samples submitted for DBA genetic studies and found that 8 (4.6%) of 173 genetically uncharacterized patients contained large mtDNA deletions. Only 2 (25%) of the patients had been diagnosed with PS on clinical grounds subsequent to sample submission. We conclude that PS can be overlooked, and that mtDNA deletion testing should be performed in the diagnostic evaluation of patients with congenital anemia.
Estimating the Polyserial Correlation Coefficient.
ERIC Educational Resources Information Center
Bedrick, Edward J.; Breslin, Frederick C.
1996-01-01
Simple noniterative estimators of the polyserial correlation coefficient are developed by exploiting a general relationship between the polyserial correlation and the point polyserial correlation to give extensions of the biserial estimators of K. Pearson (1909), H. E. Brogden (1949), and F. M. Lord (1963) to the multicategory setting. (SLD)
Sadeghifar, Jamil; Bahadori, Mohammadkarim; Baldacchino, Donia; Raadabadi, Mehdi; Jafari, Mehdi
2014-01-01
Background and Aims: Career motivation in university educators through efficient ways and appropriate with the educational system, is considered one of the important factors affecting education of students and their competence. This study aimed to determine the relationship between career motivation and spiritual leadership among a university of medical sciences in the west, Iran. Methods: This descriptive, cross-sectional correlation study was conducted among the university educators of medical sciences in the west, Iran in 2012. All of the educators (N=230) were selected and recruited according to census method. The data were collected by two established self-completed questionnaires on spiritual leadership (SL) and career motivation. Data were analyzed statistically by parametric tests: Pearson correlation, independent student t-test and one-way analysis of variance (ANOVA). Results: The Pearson correlation test identified a significant relationship between educators’ career motivation and vision, altruistic love, hope/faith, meaning/calling and membership dimensions of spiritual leadership (p<0.05). The independent t-test detected a significant relationship between the ‘hope/faith’ (p=0.04) and organizational commitment (p=0.004) dimensions and the gender of educators. ANOVA revealed significant differences in educators’ years of work experience and their overall career motivation (p=0.003) and the dimension of ‘membership’ (p<0.04). A significant relationship was found in ‘altruistic love’ and ‘Hope/faith’, and the educators’ academic rank place in the university (p=0.03). Also a significant relationship was found in ‘vision’ (p=0.03) and ‘altruistic love’ (p=0.002) and ‘membership’ (p=0.04) dimensions, and the type of faculty. Conclusion: The results indicate that the dimensions of existence of spiritual leadership may have a positive relationship with educators’ career motivation. PMID:24576374
Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments
Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.
2004-01-01
[1] The recently developed expected moments algorithm (EMA) [Cohn et al., 1997] does as well as maximum likelihood estimations at estimating log-Pearson type 3 (LP3) flood quantiles using systematic and historical flood information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study compares the performance of Bulletin 17B using the entire sample with and without regional skew with estimators that use regional skew and censor low outliers, including an extended EMA estimator, the conditional probability adjustment (CPA) from Bulletin 17B, and an estimator that uses probability plot regression (PPR) to compute substitute values for low outliers. Estimators that neglect regional skew information do much worse than estimators that use an informative regional skewness estimator. For LP3 data the low outlier rejection procedure generally results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew are generally modest in the skewness range of real interest. Samples contaminated to model actual flood data demonstrate that estimators which give special treatment to low outliers significantly outperform estimators that make no such adjustment.
Zamanzad Ghavidel, Fatemeh; Claesen, Jürgen; Burzykowski, Tomasz; Valkenborg, Dirk
2014-02-01
To extract a genuine peptide signal from a mass spectrum, an observed series of peaks at a particular mass can be compared with the isotope distribution expected for a peptide of that mass. To decide whether the observed series of peaks is similar to the isotope distribution, a similarity measure is needed. In this short communication, we investigate whether the Mahalanobis distance could be an alternative measure for the commonly employed Pearson's χ(2) statistic. We evaluate the performance of the two measures by using a controlled MALDI-TOF experiment. The results indicate that Pearson's χ(2) statistic has better discriminatory performance than the Mahalanobis distance and is a more robust measure.
Use of "t"-Test and ANOVA in Career-Technical Education Research
ERIC Educational Resources Information Center
Rojewski, Jay W.; Lee, In Heok; Gemici, Sinan
2012-01-01
Use of t-tests and analysis of variance (ANOVA) procedures in published research from three scholarly journals in career and technical education (CTE) during a recent 5-year period was examined. Information on post hoc analyses, reporting of effect size, alpha adjustments to account for multiple tests, power, and examination of assumptions…
Determining Differences in Efficacy of Two Disinfectants Using t-Tests.
ERIC Educational Resources Information Center
Brehm, Michael A.; And Others
1996-01-01
Presents an experiment to compare the effectiveness of 95% ethanol to 20% bleach as disinfectants using t-tests for the statistical analysis of the data. Reports that bleach is a better disinfectant. Discusses the statistical and practical significance of the results. (JRH)
A Spreadsheet Tool for Learning the Multiple Regression F-Test, T-Tests, and Multicollinearity
ERIC Educational Resources Information Center
Martin, David
2008-01-01
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,…
ERIC Educational Resources Information Center
Wagstaff, David A.; Elek, Elvira; Kulis, Stephen; Marsiglia, Flavio
2009-01-01
A nonparametric bootstrap was used to obtain an interval estimate of Pearson's "r," and test the null hypothesis that there was no association between 5th grade students' positive substance use expectancies and their intentions to not use substances. The students were participating in a substance use prevention program in which the unit of…
2012-01-01
Background Clinicians have long appreciated the distinct phenotype of systemic juvenile idiopathic arthritis (SJIA) compared to polyarticular juvenile idiopathic arthritis (POLY). We hypothesized that gene expression profiles of peripheral blood mononuclear cells (PBMC) from children with each disease would reveal distinct biological pathways when analyzed for significant associations with elevations in two markers of JIA activity, erythrocyte sedimentation rate (ESR) and number of affected joints (joint count, JC). Methods PBMC RNA from SJIA and POLY patients was profiled by kinetic PCR to analyze expression of 181 genes, selected for relevance to immune response pathways. Pearson correlation and Student's t-test analyses were performed to identify transcripts significantly associated with clinical parameters (ESR and JC) in SJIA or POLY samples. These transcripts were used to find related biological pathways. Results Combining Pearson and t-test analyses, we found 91 ESR-related and 92 JC-related genes in SJIA. For POLY, 20 ESR-related and 0 JC-related genes were found. Using Ingenuity Systems Pathways Analysis, we identified SJIA ESR-related and JC-related pathways. The two sets of pathways are strongly correlated. In contrast, there is a weaker correlation between SJIA and POLY ESR-related pathways. Notably, distinct biological processes were found to correlate with JC in samples from the earlier systemic plus arthritic phase (SAF) of SJIA compared to samples from the later arthritis-predominant phase (AF). Within the SJIA SAF group, IL-10 expression was related to JC, whereas lack of IL-4 appeared to characterize the chronic arthritis (AF) subgroup. Conclusions The strong correlation between pathways implicated in elevations of both ESR and JC in SJIA argues that the systemic and arthritic components of the disease are related mechanistically. Inflammatory pathways in SJIA are distinct from those in POLY course JIA, consistent with differences in clinically
Dharwadkar, Anand R; Dharwadkar, Asha A; Banu, Gouher; Bagali, Shrilaxmi
2011-01-01
The purpose of this study was to evaluate pulmonary functions in patients with Type-2 diabetes mellitus and to determine their correlation with glycemic status of diabetes in Indian population. Forty Type-2 diabetic patients, aged 30-60 years, with diabetic duration of 1-20 years, were included in the study. FVC, FEV1, & FEV1% are recorded by Benedict's Roth spirometer. PEFR and MEP were recorded by Wright's Peak flow meter & Modified Black's apparatus. Glycemic status of subjects was determined by FBS & PPBS by Glucose oxidase & peroxidase methods. And results were analyzed by calculating Mean +/- SD, using Student's t test, and Pearson correlation. All the respiratory parameters are reduced in Type-2 diabetic patients compared to control of which FEV1, FEV1%, & MEP show very highly significant reduction (P=0.000). Lung functions are negatively correlated with glycemic status & duration of diabetes. (r = -0.390, & -0.342) Reduction in dynamic lung functions and its negative correlation to glycemic status might be due to respiratory muscle weakness as indicated by highly significant reduction in MEP. Hence strict glycemic control and breathing exercises to strengthen the respiratory muscles may improve lung function in diabetics. PMID:22319899
Chen, Chun-Ming; Lai, Steven; Chen, Ker-Kong; Lee, Huey-Er
2015-01-01
Purpose. The aim of this study was to determine the correlation between the pharyngeal airway space and head posture after mandibular setback surgery for mandibular prognathism. Materials and Methods. Serial lateral cephalograms of 37 patients with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) were evaluated before (T1) and immediately (T2), between 6 weeks and 3 months (T3), and more than 1 year (T4) after surgery. Paired t-tests and Pearson's correlation analysis were used to evaluate the postoperative changes in all cephalometric parameters, including the mandible, hyoid, head posture (craniocervical angle), and pharyngeal airway space. Results. The mandible and hyoid were set back by 12.8 mm and 4.9 mm, respectively, at T2. Furthermore, the hyoid showed significant inferior movement of 10.7 mm, with an 8 mm increase in the tongue depth. The upper oropharyngeal airway (UOP) shortened by 4.1 mm, the lower oropharyngeal airway (LOP) by 1.7 mm, and the laryngopharyngeal airway by 2 mm. The craniocervical angle showed a significant increase of 2.8°. UOP and LOP showed a significant correlation with the craniocervical angle at T2 and T4. Conclusions. Our findings conclude that the oropharyngeal airway space is significantly decreased and correlated with a change in the head posture after mandibular setback surgery. PMID:25977919
Reducing Bias and Error in the Correlation Coefficient Due to Nonnormality
ERIC Educational Resources Information Center
Bishara, Anthony J.; Hittner, James B.
2015-01-01
It is more common for educational and psychological data to be nonnormal than to be approximately normal. This tendency may lead to bias and error in point estimates of the Pearson correlation coefficient. In a series of Monte Carlo simulations, the Pearson correlation was examined under conditions of normal and nonnormal data, and it was compared…
Song, Young Dong; Jain, Nimash; Kang, Yeon Gwi; Kim, Tae Yune
2016-01-01
Purpose Correlations between maximum flexion and functional outcomes in total knee arthroplasty (TKA) patients are reportedly weak. We investigated whether there are differences between passive maximum flexion in nonweight bearing and other types of maximum flexion and whether the type of maximum flexion correlates with functional outcomes. Materials and Methods A total of 210 patients (359 knees) underwent preoperative evaluation and postoperative follow-up evaluations (6, 12, and 24 months) for the assessment of clinical outcomes including maximum knee flexion. Maximum flexion was measured under five conditions: passive nonweight bearing, passive weight bearing, active nonweight bearing, and active weight bearing with or without arm support. Data were analyzed for relationships between passive maximum flexion in nonweight bearing by Pearson correlation analyses, and a variance comparison between measurement techniques via paired t test. Results We observed substantial differences between passive maximum flexion in nonweight bearing and the other four maximum flexion types. At all time points, passive maximum flexion in nonweight bearing correlated poorly with active maximum flexion in weight bearing with or without arm support. Active maximum flexion in weight bearing better correlated with functional outcomes than the other maximum flexion types. Conclusions Our study suggests active maximum flexion in weight bearing should be reported together with passive maximum flexion in nonweight bearing in research on the knee motion arc after TKA. PMID:27274468
A Pearson-type goodness-of-fit test for stationary and time-continuous Markov regression models.
Aguirre-Hernández, R; Farewell, V T
2002-07-15
Markov regression models describe the way in which a categorical response variable changes over time for subjects with different explanatory variables. Frequently it is difficult to measure the response variable on equally spaced discrete time intervals. Here we propose a Pearson-type goodness-of-fit test for stationary Markov regression models fitted to panel data. A parametric bootstrap algorithm is used to study the distribution of the test statistic. The proposed technique is applied to examine the fit of a Markov regression model used to identify markers for disease progression in psoriatic arthritis.
Lakens, Daniël
2013-01-01
Effect sizes are the most important outcome of empirical studies. Most articles on effect sizes highlight their importance to communicate the practical significance of results. For scientists themselves, effect sizes are most useful because they facilitate cumulative science. Effect sizes can be used to determine the sample size for follow-up studies, or examining effects across studies. This article aims to provide a practical primer on how to calculate and report effect sizes for t-tests and ANOVA's such that effect sizes can be used in a-priori power analyses and meta-analyses. Whereas many articles about effect sizes focus on between-subjects designs and address within-subjects designs only briefly, I provide a detailed overview of the similarities and differences between within- and between-subjects designs. I suggest that some research questions in experimental psychology examine inherently intra-individual effects, which makes effect sizes that incorporate the correlation between measures the best summary of the results. Finally, a supplementary spreadsheet is provided to make it as easy as possible for researchers to incorporate effect size calculations into their workflow. PMID:24324449
Correlation between cell cycle proteins and hMSH2 in actinic cheilitis and lip cancer.
Lopes, Maria Luiza Diniz de Sousa; de Oliveira, Denise Hélen Imaculada Pereira; Sarmento, Dmitry José de Santana; Queiroz, Lélia Maria Guedes; Miguel, Márcia Cristina da Costa; da Silveira, Éricka Janine Dantas
2016-04-01
This study aims to evaluate and verify the relationship between the immunoexpression of hMSH2, p53 and p21 in actinic cheilitis (AC) and lower lip squamous cell carcinoma (SCC) cases. Forty AC and 40 SCC cases were submitted to immunoperoxidase method and quantitatively analyzed. Expression was compared by Mann-Whitney test, Student t test or one-way ANOVA. To correlate the variables, Pearson's correlation coefficient was calculated. The expression of p53 and p21 showed no significant differences between histopathological grades of AC or lower lip SCC (p > 0.05). Immunoexpression of p53 was higher in SCC than in AC (p < 0.001), while p21 expression was more observed in AC when compared to SCC group (p = 0.006). The AC group revealed an inverse correlation between p53 and hMSH2 expression (r = -0.30, p = 0.006). Alterations in p53 and p21 expression suggest that these proteins are involved in lower lip carcinogenesis. Moreover, p53 and hMSH2 seem to be interrelated in early events of this process. PMID:26842232
Rivas-Ruiz, Rodolfo; Pérez-Rodríguez, Marcela; Talavera, Juan O
2013-01-01
Among the test to show differences between means, the Student t test is the most characteristic. Its basic algebraic structure shows the difference between two means weighted by their dispersion. In this way, you can estimate the p value and the 95 % confidence interval of the mean difference. An essential feature is that the variable from which the mean is going to be calculated must have a normal distribution. The Student t test is used to compare two unrelated means (compared between two maneuvers), this is known as t test for independent samples. It is also used to compare two related means (a comparison before and after a maneuver in just one group), what is called paired t test. When the comparison is between more than two means (three or more dependent means, or three or more independent means) an ANOVA test (or an analysis of variance) it is used to perform the analysis.
[An electric T test topographic map study of the brain in uremia].
Song, J H; Li, Q S
1989-10-01
This paper reports the results of statistical mapping on cerebral electric power abnormal distributions in 35 cases of uremia, using cerebral electrical T test topographical map method. The results indicated that the abnormal wide distribution of cerebro-electric activity of uremia was significant (P less than 0.01). The power density of slow wave markedly increased in the right parietal region. The power density of alpha wave obviously decreased in the right parietal side. This study clearly showed that the brain lesions have both the generality of diffuse damage and the particularity of focal damage. A region was seriously invaded by the lesion. The brain lesions have metabolic and toxic encephalopathic features.
Reassess the t Test: Interact with All Your Data via ANOVA.
Brady, Siobhan M; Burow, Meike; Busch, Wolfgang; Carlborg, Örjan; Denby, Katherine J; Glazebrook, Jane; Hamilton, Eric S; Harmer, Stacey L; Haswell, Elizabeth S; Maloof, Julin N; Springer, Nathan M; Kliebenstein, Daniel J
2015-08-01
Plant biology is rapidly entering an era where we have the ability to conduct intricate studies that investigate how a plant interacts with the entirety of its environment. This requires complex, large studies to measure how plant genotypes simultaneously interact with a diverse array of environmental stimuli. Successful interpretation of the results from these studies requires us to transition away from the traditional standard of conducting an array of pairwise t tests toward more general linear modeling structures, such as those provided by the extendable ANOVA framework. In this Perspective, we present arguments for making this transition and illustrate how it will help to avoid incorrect conclusions in factorial interaction studies (genotype × genotype, genotype × treatment, and treatment × treatment, or higher levels of interaction) that are becoming more prevalent in this new era of plant biology.
Reassess the t Test: Interact with All Your Data via ANOVA
Brady, Siobhan M.; Burow, Meike; Busch, Wolfgang; Carlborg, Örjan; Denby, Katherine J.; Glazebrook, Jane; Hamilton, Eric S.; Harmer, Stacey L.; Haswell, Elizabeth S.; Maloof, Julin N.; Springer, Nathan M.; Kliebenstein, Daniel J.
2015-01-01
Plant biology is rapidly entering an era where we have the ability to conduct intricate studies that investigate how a plant interacts with the entirety of its environment. This requires complex, large studies to measure how plant genotypes simultaneously interact with a diverse array of environmental stimuli. Successful interpretation of the results from these studies requires us to transition away from the traditional standard of conducting an array of pairwise t tests toward more general linear modeling structures, such as those provided by the extendable ANOVA framework. In this Perspective, we present arguments for making this transition and illustrate how it will help to avoid incorrect conclusions in factorial interaction studies (genotype × genotype, genotype × treatment, and treatment × treatment, or higher levels of interaction) that are becoming more prevalent in this new era of plant biology. PMID:26220933
Correlation as Probability of Common Descent.
ERIC Educational Resources Information Center
Falk, Ruma; Well, Arnold D.
1996-01-01
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…
Is the G Index a Correlation Coefficient?
ERIC Educational Resources Information Center
Vegelius, Jan
1980-01-01
One argument against the G index is that, unlike phi, it is not a correlation coefficient; yet, G conforms to the Kendall and E-coefficient definitions. The G index is also equal to the Pearson product moment correlation coefficient obtained from double scoring. (Author/CP)
Beuret, J; Scott, D A; Pearson, J C
2000-05-01
Magnacercous cercariae, all morphologically identical but with different coloured tails, were found naturally infecting the intertidal prosobranch gastropod Clypeomorus batillariaeformis Habe & Kosuge (Cerithiidae) at Heron and Masthead Islands. Several species of coral-dwelling fishes were exposed to magnacercous cercariae. Active ingestion by the fish, followed by the complete development of the metacercaria in the optic lobes, occurred in Pomacentrus molluccensis Bleeker, but not in Dascyllus aruanus (L.), where development stopped short after encystment. All cercariae turned out to belong to the same species, Galactosomum bearupi Pearson, 1973. Natural infections of G. bearupi metacercariae were found in eight species of fish at Heron Island: Pomacentrus molluccensis, P. wardi Whitley, P. bankanensis Bleeker, P. flavicauda Whitley, Stegastes cf. fasciolatus (Ogilby), Sillago maculata Quoy & Gaimard, S. cf. ciliata Cuvier and Crenimugil crenilabris (Forsskål). This represents the fourth account of the cercaria of a species of Galactosomum.
Cerioli, Andrea
2002-12-01
A common feature of data collected in environmental and earth sciences is that they typically exhibit spatial autocorrelation. Violating the assumption of independent observations can have dramatic effects on inferences derived from standard statistical methods. In this article, we examine the consequences of spatial autocorrelation on Pearson's chi-squared test of mutual independence between two categorical responses with a general number of classes. Correspondingly, we suggest a simple modification to the standard test statistic that allows for spatial autocorrelation. Our modified statistic is based on a first-order correction factor and thus provides only an approximate test. However, we show by Monte Carlo simulation that this approximation results in satisfactory inferences in several situations of practical interest. The usefulness of the method is displayed through an application to categorical data arising in the study of the relationship between the distribution pattern of plant species and woodland age in a forest in northern Belgium.
Discrete Pearson distributions
Bowman, K.O. ); Shenton, L.R. ); Kastenbaum, M.A. , Basye, VA )
1991-11-01
These distributions are generated by a first order recursive scheme which equates the ratio of successive probabilities to the ratio of two corresponding quadratics. The use of a linearized form of this model will produce equations in the unknowns matched by an appropriate set of moments (assumed to exist). Given the moments we may find valid solutions. These are two cases; (1) distributions defined on the non-negative integers (finite or infinite) and (2) distributions defined on negative integers as well. For (1), given the first four moments, it is possible to set this up as equations of finite or infinite degree in the probability of a zero occurrence, the sth component being a product of s ratios of linear forms in this probability in general. For (2) the equation for the zero probability is purely linear but may involve slowly converging series; here a particular case is the discrete normal. Regions of validity are being studied. 11 refs.
Clustering stocks using partial correlation coefficients
NASA Astrophysics Data System (ADS)
Jung, Sean S.; Chang, Woojin
2016-11-01
A partial correlation analysis is performed on the Korean stock market (KOSPI). The difference between Pearson correlation and the partial correlation is analyzed and it is found that when conditioned on the market return, Pearson correlation coefficients are generally greater than those of the partial correlation, which implies that the market return tends to drive up the correlation between stock returns. A clustering analysis is then performed to study the market structure given by the partial correlation analysis and the members of the clusters are compared with the Global Industry Classification Standard (GICS). The initial hypothesis is that the firms in the same GICS sector are clustered together since they are in a similar business and environment. However, the result is inconsistent with the hypothesis and most clusters are a mix of multiple sectors suggesting that the traditional approach of using sectors to determine the proximity between stocks may not be sufficient enough to diversify a portfolio.
Correlation between subjective and objective assessment of magnetic resonance (MR) images.
Chow, Li Sze; Rajagopal, Heshalini; Paramesran, Raveendran
2016-07-01
Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images. PMID:26969762
Correlation between subjective and objective assessment of magnetic resonance (MR) images.
Chow, Li Sze; Rajagopal, Heshalini; Paramesran, Raveendran
2016-07-01
Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images.
Rigel, Darrell S.; Ferris, Laura; Sober, Arthur; Tucker, Natalie; Cockerell, Clay J.
2016-01-01
Objective: To correlate Multi-spectral Digital Skin Lesion Analysis classifier scores with histopathological severity of pigmented lesions and clinical features of melanoma. Design: Classifier scores were computed for 1,632 skin lesions. Dermatologists evaluated the same lesions for Asymmetry, Border Irregularity, Color variegation, Diameter >6mm, Evolution, Patient’s Concern, Regression, and/or “Ugly Duckling” sign. Classifier scores were correlated to the number of clinical risk features and for six histopathological severity levels of pigmented lesions. Measurements: Average classifier score, Welch’s t-test, and chi-square analysis. Results: Melanomas had higher mean classifier scores (3.5) than high-grade dysplastic nevi (2.7, p=0.002), low-grade dysplastic nevi (1.7, p<0.0001), non-dysplastic nevi (1.6, p<0.0001), and benign non-melanocytic lesions (2.0, p<0.0001). Classifier score and the number of clinical risk characteristics directly correlated (Pearson coefficient 0.32, p<0.0001). Conclusion: Correlation of classifier scores to clinical and histological melanoma features supports the effectiveness of Multi-spectral Digital Skin Lesion Analysis in assessing the risk of pigmented lesions requiring biopsy. Optimizing outcomes of dermatologist decisions to biopsy suspicious pigmented lesions may be enhanced utilizing Multi-spectral Digital Skin Lesion Analysis. PMID:27354886
Boareto, Marcelo; Caticha, Nestor
2014-01-01
Microarray data analysis typically consists in identifying a list of differentially expressed genes (DEG), i.e., the genes that are differentially expressed between two experimental conditions. Variance shrinkage methods have been considered a better choice than the standard t-test for selecting the DEG because they correct the dependence of the error with the expression level. This dependence is mainly caused by errors in background correction, which more severely affects genes with low expression values. Here, we propose a new method for identifying the DEG that overcomes this issue and does not require background correction or variance shrinkage. Unlike current methods, our methodology is easy to understand and implement. It consists of applying the standard t-test directly on the normalized intensity data, which is possible because the probe intensity is proportional to the gene expression level and because the t-test is scale- and location-invariant. This methodology considerably improves the sensitivity and robustness of the list of DEG when compared with the t-test applied to preprocessed data and to the most widely used shrinkage methods, Significance Analysis of Microarrays (SAM) and Linear Models for Microarray Data (LIMMA). Our approach is useful especially when the genes of interest have small differences in expression and therefore get ignored by standard variance shrinkage methods.
England, J.F.; Salas, J.D.; Jarrett, R.D.
2003-01-01
The expected moments algorithm (EMA) [Cohn et al., 1997] and the Bulletin 17B [Interagency Committee on Water Data, 1982] historical weighting procedure (B17H) for the log Pearson type III distribution are compared by Monte Carlo computer simulation for cases in which historical and/or paleoflood data are available. The relative performance of the estimators was explored for three cases: fixed-threshold exceedances, a fixed number of large floods, and floods generated from a different parent distribution. EMA can effectively incorporate four types of historical and paleoflood data: floods where the discharge is explicitly known, unknown discharges below a single threshold, floods with unknown discharge that exceed some level, and floods with discharges described in a range. The B17H estimator can utilize only the first two types of historical information. Including historical/paleoflood data in the simulation experiments significantly improved the quantile estimates in terms of mean square error and bias relative to using gage data alone. EMA performed significantly better than B17H in nearly all cases considered. B17H performed as well as EMA for estimating X100 in some limited fixed-threshold exceedance cases. EMA performed comparatively much better in other fixed-threshold situations, for the single large flood case, and in cases when estimating extreme floods equal to or greater than X500. B17H did not fully utilize historical information when the historical period exceeded 200 years. Robustness studies using GEV-simulated data confirmed that EMA performed better than B17H. Overall, EMA is preferred to B17H when historical and paleoflood data are available for flood frequency analysis.
Yeom, HeyRi; Blanchard, Steven; Kim, Seokjin; Zunt, Susan; Chu, Tien-Min G
2008-03-01
Conventional histologic or histomorphometric evaluation provides clear evidence of the bone healing process. However, the sample preparation process is tedious and destructive, and the three-dimensional (3D) anisotropic information of the bone trabeculae is compromised. Micro-computed tomography (microCT) has been introduced as an alternative to these traditional evaluation methods. microCT is noninvasive and provides a faster approach to evaluate and quantify cancellous bone. Most previous studies that used microCT have focused on studying trabecular structures of cancellous bone. In this study, we used microCT to analyze the micro-architecture of the regenerated membranous bone using a rabbit cranial defect model. Two 1 cm diameter circular bony defects were created in 12 New Zealand white rabbits. Specimens were harvested at 6 weeks and 12 weeks after surgery and were scanned using a MicroCT machine (Skyscan 1072, Aartselaar, Belgium). The specimens were then sectioned and stained with Goldner's trichrome. Bone volume density (BV/TV), bone surface density (BS/BV), and trabecular thickness (TbTh) were determined from histomorphometric and two-dimensional (2D) and 3D microCT analysis. Pearson's correlation coefficient (gamma), paired t-tests, and intraclass correlation coefficients from measurements between the 2D and 3D microCT and histomorphometry were calculated. There were very strong positive correlations of BV/TV between histomorphometric and 2D or 3D microCT measurements. Correlation between histomorphometric and 2D microCT measurements for BS/BV was moderate, whereas correlation between histomorphometric and 3D microCT measurements was weak. Weak correlations in TbTh among the three methods were found. In conclusion, the present study suggests that, in evaluating micro-architectures in regenerated bones, the correlation between measuring methods vary according to the features measured. PMID:18362725
Infiltrating Mast Cells Correlate with Angiogenesis in Bone Metastases from Gastric Cancer Patients
Ammendola, Michele; Marech, Ilaria; Sammarco, Giuseppe; Zuccalà, Valeria; Luposella, Maria; Zizzo, Nicola; Patruno, Rosa; Crovace, Alberto; Ruggieri, Eustachio; Zito, Alfredo Francesco; Gadaleta, Cosmo Damiano; Sacco, Rosario; Ranieri, Girolamo
2015-01-01
While gastric cancer is a well established angiogenesis driven tumor, no data has been published regarding angiogenesis stimulated by mast cells (MCs) positive for tryptase in bone metastases from gastric cancer patients (BMGCP). It is well established that MCs play a role in immune responses and more recently it was demonstrated that MCs have been involved in tumor angiogenesis. We analyzed infiltrating MCs and neovascularization in BMGCP diagnosed by histology. A series of 15 stage T3-4N2-3M1 (by AJCC for Gastric Cancer Staging 7th Edition) BMGCP from bone biopsies were selected. Tumour tissue samples were evaluated by mean of immunohistochemistry and image analysis methods in terms of MCs density positive to tryptase (MCDPT), MCs area positive to tryptase (MCAPT), microvascular density (MVD) and endothelial area (EA). A significant correlation between MCDPT, MCAPT, MVD and EA groups to each other was found by Pearson and t-test analysis (r ranged from 0.68 to 0.82; p-value ranged from 0.00 to 0.02). Our very preliminary data suggest that infiltrating MCs positive for tryptase may play a role in BMGCP angiogenesis, and could be further evaluated as a novel target of anti-angiogenic therapy. PMID:25648323
ERIC Educational Resources Information Center
Dugger-Roberts, Cherith A.
2014-01-01
The purpose of this quantitative study was to determine if there was a relationship between the TCAP test and Pearson Benchmark assessment in elementary students' reading and language arts and math performance in a northeastern Tennessee school district. This study involved 3rd, 4th, 5th, and 6th grade students. The study focused on the following…
NASA Astrophysics Data System (ADS)
Ramesh, Azadeh; Glade, Thomas; Malet, Jean-Philippe
2010-09-01
The existence of a trend in hydrological and meteorological time series is detected by statistical tests. The trend analysis of hydrological and meteorological series is important to consider, because of the effects of global climate change. Parametric or non-parametric statistical tests can be used to decide whether there is a statistically significant trend. In this paper, first a homogeneity analysis was performed by using the non-parametric Bartlett test. Then, trend detection was estimated by using non-parametric Mann-Kendall test. The null hypothesis in the Mann-Kendall test is that the data are independent and randomly ordered. The result of Mann-Kendall test was compared with the parametric T-Test for finding the existence of trend. To reach this purpose, the significance of trends was analyzed on monthly data of Ubaye river in Barcelonnette watershed in southeast of France at an elevation of 1132 m (3717 ft) during the period from 1928 to 2009 bases with the nonparametric Mann-Kendall test and parametric T-Test for river discharge and for meteorological data. The result shows that a rainfall event does not necessarily have an immediate impact on discharge. Visual inspection suggests that the correlation between observations made at the same time point is not very strong. In the results of the trend tests the p-value of the discharge is slightly smaller than the p-value of the precipitation but it seems that in both there is no statistically significant trend. In statistical hypothesis testing, a test statistic is a numerical summary of a set of data that reduces the data to one or a small number of values that can be used to perform a hypothesis test. Statistical hypothesis testing is determined if there is a significant trend or not. Negative test statistics and MK test in both precipitation and discharge data indicate downward trends. As conclusion we can say extreme flood event during recent years is strongly depending on: 1) location of the city: It is
NASA Astrophysics Data System (ADS)
Yuzurihara, Hirotaka; Hayama, Kazuhiro; Mano, Shuhei; Verkindt, Didier; Kanda, Nobuyuki
2016-08-01
Noise hunting is a critical requirement for realizing design sensitivity of a detector, and consequently, noise origins and its features have been revealed partially. Among the noise sources to be hunted, sources of nonlinearly correlated noise, such up-conversion noise, are hard to find and can limit the sensitivity of gravitational wave searches with advanced detectors. We propose using a correlation analysis method called maximal information coefficient (MIC) to find both nonlinear and linear correlations. We apply MIC to the scattered light noise correlated between the seismic activity and the strain signal, which limited the sensitivity of the Virgo detector during the first science run. The results show that MIC can find nonlinearly correlated noise more efficiently than the Pearson correlation method. When the data is linearly correlated, the efficiency of the Pearson method and MIC is comparable. On the other hand, when the data is known to be nonlinearly correlated, MIC finds the correlation while the Pearson method fails completely.
INTERPRETING THE DISTANCE CORRELATION RESULTS FOR THE COMBO-17 SURVEY
Richards, Mercedes T.; Richards, Donald St. P.; Martínez-Gómez, Elizabeth E-mail: richards@stat.psu.edu
2014-04-01
The accurate classification of galaxies in large-sample astrophysical databases of galaxy clusters depends sensitively on the ability to distinguish between morphological types, especially at higher redshifts. This capability can be enhanced through a new statistical measure of association and correlation, called the distance correlation coefficient, which has more statistical power to detect associations than does the classical Pearson measure of linear relationships between two variables. The distance correlation measure offers a more precise alternative to the classical measure since it is capable of detecting nonlinear relationships that may appear in astrophysical applications. We showed recently that the comparison between the distance and Pearson correlation coefficients can be used effectively to isolate potential outliers in various galaxy data sets, and this comparison has the ability to confirm the level of accuracy associated with the data. In this work, we elucidate the advantages of distance correlation when applied to large databases. We illustrate how the distance correlation measure can be used effectively as a tool to confirm nonlinear relationships between various variables in the COMBO-17 database, including the lengths of the major and minor axes, and the alternative redshift distribution. For these outlier pairs, the distance correlation coefficient is routinely higher than the Pearson coefficient since it is easier to detect nonlinear relationships with distance correlation. The V-shaped scatter plots of Pearson versus distance correlation coefficients also reveal the patterns with increasing redshift and the contributions of different galaxy types within each redshift range.
NASA Astrophysics Data System (ADS)
Takeda, Akira; Takata, Kazuyuki; Nagao, Hirotomo; Wang, Jianqing; Fujiwara, Osamu
We previously measured for healthy subjects and patients who require hemodialysis the complex relative permittivity (εr´-jεr´´) of whole blood, and found that εr´-axis intercept εrt´ of straight line approximation to the Cole-Cole plots at frequencies from 200 MHz to 1GHz is significantly different with a level of less than 1% among its averaged values for healthy subjects and patients before and after dialysis, though any correlations between εrt´ and blood urea nitrogen (BUN) and creatinine being used as main indices for hemodialysis evaluation have not so far been clarified. In this study, to make correlation analyses between the intercept εrt´ and blood biochemical components for nine patients before and after hemodialysis, we measured six kinds of their blood components including BUN and creatinine, and calculated their Pearson product-moment correlation coefficients for εrt´ along with significant probability P based on a t-test. It should be noted that P is a reference probability to determine whether or not a null hypothesis can be rejected, and that the P value of 0.05 is commonly used as a significance level for statistical test. As a result, we found that a strong correlation with P < 0.05 is observed between εrt´ and albumin, while there are not always significant correlations with P > 0.05 between εrt´ and other blood components including BUN and creatinine. Although albumin is not used as an index for hemodialysis efficiency, it can reflect water amount in blood vessels and liver operation. This finding implies that εrt´ could be used as an index for evaluating blood viscosity and liver function.
Bradley, Michael T; Brand, Andrew
2016-10-01
Accurate measurement and a cutoff probability with inferential statistics are not wholly compatible. Fisher understood this when he developed the F test to deal with measurement variability and to make judgments on manipulations that may be worth further study. Neyman and Pearson focused on modeled distributions whose parameters were highly determined and concluded that inferential judgments following an F test could be made with accuracy because the distribution parameters were determined. Neyman and Pearson's approach in the application of statistical analyses using alpha and beta error rates has played a dominant role guiding inferential judgments, appropriately in highly determined situations and inappropriately in scientific exploration. Fisher tried to explain the different situations, but, in part due to some obscure wording, generated a long standing dispute that currently has left the importance of Fisher's p < .05 criteria not fully understood and a general endorsement of the Neyman and Pearson error rate approach. Problems were compounded with power calculations based on effect sizes following significant results entering into exploratory science. To understand in a practical sense when each approach should be used, a dimension reflecting varying levels of certainty or knowledge of population distributions is presented. The dimension provides a taxonomy of statistical situations and appropriate approaches by delineating four zones that represent how well the underlying population of interest is defined ranging from exploratory situations to highly determined populations.
Bradley, Michael T; Brand, Andrew
2016-10-01
Accurate measurement and a cutoff probability with inferential statistics are not wholly compatible. Fisher understood this when he developed the F test to deal with measurement variability and to make judgments on manipulations that may be worth further study. Neyman and Pearson focused on modeled distributions whose parameters were highly determined and concluded that inferential judgments following an F test could be made with accuracy because the distribution parameters were determined. Neyman and Pearson's approach in the application of statistical analyses using alpha and beta error rates has played a dominant role guiding inferential judgments, appropriately in highly determined situations and inappropriately in scientific exploration. Fisher tried to explain the different situations, but, in part due to some obscure wording, generated a long standing dispute that currently has left the importance of Fisher's p < .05 criteria not fully understood and a general endorsement of the Neyman and Pearson error rate approach. Problems were compounded with power calculations based on effect sizes following significant results entering into exploratory science. To understand in a practical sense when each approach should be used, a dimension reflecting varying levels of certainty or knowledge of population distributions is presented. The dimension provides a taxonomy of statistical situations and appropriate approaches by delineating four zones that represent how well the underlying population of interest is defined ranging from exploratory situations to highly determined populations. PMID:27502529
BEIRANVAND, Reza; KARIMI, Asrin; DELPISHEH, Ali; SAYEHMIRI, Kourosh; SOLEIMANI, Samira; GHALAVANDI, Shahnaz
2016-01-01
Background: Tuberculosis (TB) spread pattern is influenced by geographic and social factors. Nowadays Geographic Information System (GIS) is one of the most important epidemiological instrumentation identifying high-risk population groups and geographic areas of TB. The aim of this study was to determine the correlation between climate and geographic distribution of TB in Khuzestan Province using GIS during 2005–2012. Methods: Through an ecological study, all 6363 patients with definite diagnosis of TB from 2005 until the end of September 2012 in Khuzestan Province, southern Iran were diagnosed. Data were recorded using TB- Register software. Tuberculosis incidence based on the climate and the average of annual rain was evaluated using GIS. Data were analyzed through SPSS software. Independent t-test, ANOVA, Linear regression, Pearson and Eta correlation coefficient with a significance level of less than 5% were used for the statistical analysis. Results: The TB incidence was different in various geographic conditions. The highest mean of TB cumulative incidence rate was observed in extra dry areas (P= 0.017). There was a significant inverse correlation between annual rain rate and TB incidence rate (R= −0.45, P= 0.001). The lowest TB incidence rate (0–100 cases per 100,000) was in areas with the average of annual rain more than 1000 mm (P= 0.003). Conclusion: The risk of TB has a strong relationship with climate and the average of annual rain, so that the risk of TB in areas with low annual rainfall and extra dry climate is more than other regions. Services and special cares to high-risk regions of TB are recommended. PMID:27057526
Kumar, Ashish; Rana, Vivek; Aggarwal, Abhai; Chandra, Lokesh
2013-01-01
ABSTRACT Aims: To assess the relationship of anterior tooth fractures with type of occlusion and craniofacial morphology. Materials and methods: The study was conducted on 76 subjects of age group 9 to 13 years with at least one fractured permanent anterior teeth. Lateral cephalograms were taken and study models were prepared for each subject with prior consent of their parents. Then cephalometric tracings were done and overjet was recorded through study models. Statistical analysis used: Standard error of mean (SEM) and unpaired t-test has been applied to test the significant difference between the seven parameters under consideration. Karl Pearson correlation test has also been used to correlate all the parameters used in this study with each other. All the tests were performed at 5 and 1% levels of significance. Results: Frequency of tooth fracture increases with increasing overjet. At 5% level of significance, significant difference were observed between the standard values and observed values for overjet measurement, SNA angle, SNB angle, ANB angle, upper incisor to NA (angle), upper incisor to NA (linear) and interincisal angle for overall data and also for both male and female data separately. Conclusion: Probability of permanent anterior tooth fracture increases with increasing overjet. A significant difference was observed between the standard value and the observed values of all parameters under consideration. How to cite this article: Chaturvedi R, Kumar A, Rana V, Aggarwal A, Chandra L. A Correlation of Permanent Anterior Tooth Fracture with Type of Occlusion and Craniofacial Morphology. Int J Clin Pediatr Dent 2013;6(2):80-84. PMID:25206197
Bindal, Usha Dudeja; Siddiqui, Merajul Haque; Sharma, Dilutpal
2016-01-01
Introduction Despite, various preventive efforts on conventional cardiovascular disease (CVD) risk factors, the incidence of CVD in rheumatoid arthritis (RA) patients increases continuously. To solve this conundrum one needs more investigations. Aim The present study was conducted to evaluate the plasma paraoxonase (PON) activity along with the markers of systemic inflammation, oxidative stress and disease activity score-28 (DAS28) in RA patients and clarify their role in determining the probability of RA patients to develop future CVD risk. Materials and Methods Plasma PON, total antioxidant activity (TAA), C-reactive protein (CRP), synovial interleukin-6 (IL-6) and erythrocyte malondialdehyde (MDA) levels were estimated in 40 RA patients aged 40-55 years aged and 40 age-matched healthy controls. The data obtained were compared statistically by using Student’s t-test and Pearson correlation test. Results Besides dyslipidaemia, marked reduction in plasma PON and TAA (p< 0.05) were observed in RA patients as compared with that of healthy controls. Erythrocyte MDA, plasma CRP and synovial IL-6 levels were increased significantly (p<0.05) in RA patients. PON was negatively correlated with MDA (r = - 0.672; p < 0.001), CRP (r = -0.458; p<0.05), IL-6 (r = -0.426; p<0.05) and DAS28 (r = -0.598; p < 0.001), and positively correlated with HDL cholesterol (r = 0.648; p<0.001) and TAA (r = 0.608; p< 0.001) levels in RA patients. Conclusion Alteration in PON activity might contribute to the progression of future CVD risk in RA patients, which may result from interplay of several confounding factors, such as inflammation, oxidative stress and dyslipidaemia. Furthermore, plasma PON activity, CRP and TAA levels could be considered as non-traditional factors to predict CVD risk. Thus, it is suggested that future drugs could be developed to target the non-traditional risk factors in RA patients. PMID:27134854
NASA Astrophysics Data System (ADS)
Gebresellasie, K.; Shirokoff, J.; Lewis, J. C.
2012-12-01
X-ray line spectra profile fitting using Pearson VII, pseudo-Voigt and generalized Fermi functions was performed on asphalt binders prior to the calculation of aromaticity and crystallite size parameters. The effects of these functions on the results are presented and discussed in terms of the peak profile fit parameters, the uncertainties in calculated values that can arise owing to peak shape, peak features in the pattern and crystallite size according to the asphalt models (Yen, modified Yen or Yen-Mullins) and theories. Interpretation of these results is important in terms of evaluating the performance of asphalt binders widely used in the application of transportation systems (roads, highways, airports).
ERIC Educational Resources Information Center
Krijnen, Wim P.
1994-01-01
To assess association between rows of proximity matrices, H. de Vries (1993) introduces weighted average and row-wise average variants for Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank correlation. For all three, the absolute value of the first variant is greater than or equal to the second. (SLD)
ERIC Educational Resources Information Center
Chan, Wai; Chan, Daniel W.-L.
2004-01-01
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…
Ammendola, Michele; Sacco, Rosario; Sammarco, Giuseppe; Piardi, Tullio; Zuccalà, Valeria; Patruno, Rosa; Zullo, Alessandra; Zizzo, Nicola; Nardo, Bruno; Marech, Ilaria; Crovace, Alberto; Gadaleta, Cosmo Damiano; Pessaux, Patrick; Ranieri, Girolamo
2016-01-01
Background Mast cells (MCs) can stimulate angiogenesis, releasing several proangiogenic cytokines stored in their cytoplasm. In particular MCs can release tryptase, a potent in vivo and in vitro proangiogenic factor via proteinase-activated receptor-2 (PAR-2) activation and mitogen-activated protein kinase phosphorylation. Nevertheless, no data are available concerning the relationship between MC density positive to tryptase (MCDPT), endothelial cells positive to PAR-2 forming microvascular density (PAR-2-MVD), and classical MVD (C-MVD) in hepatocellular carcinoma (HCC) angiogenesis. This study analyzed the correlation between MCDPT, PAR-2-MVD, and C-MVD, each correlated to the others and to the main clinicopathological features, in early HCC patients who underwent surgery. Methods A series of 53 HCC patients with early stage (stage 0 according to the Barcelona Clinic Liver Cancer Staging Classification) were selected and then underwent surgery. Tumor tissue samples were evaluated by means of immunohistochemistry and image analysis methods in terms of number of MCDPT, PAR-2-MVD, and C-MVD. Results A significant correlation between MCDPT, PAR-2-MVD, and C-MVD groups, each correlated to the others, was found by Pearson t-test analysis (r ranged from 0.67 to 0.81; P-value ranged from 0.01 to 0.03). No other significant correlation was found. Conclusion Our in vivo pilot data suggest that MCDPT and PAR-2-MVD may play a role in HCC angiogenesis and could be further evaluated as a target of antiangiogenic therapy. PMID:27499640
Testing Dependent Correlations with Nonoverlapping Variables: A Monte Carlo Simulation
ERIC Educational Resources Information Center
Silver, N. Clayton; Hittner, James B.; May, Kim
2004-01-01
The authors conducted a Monte Carlo simulation of 4 test statistics or comparing dependent correlations with no variables in common. Empirical Type 1 error rates and power estimates were determined for K. Pearson and L. N. G. Filon's (1898) z, O. J. Dunn and V. A. Clark's (1969) z, J. H. Steiger's (1980) original modification of Dunn and Clark's…
Distribution of the two-sample t-test statistic following blinded sample size re-estimation.
Lu, Kaifeng
2016-05-01
We consider the blinded sample size re-estimation based on the simple one-sample variance estimator at an interim analysis. We characterize the exact distribution of the standard two-sample t-test statistic at the final analysis. We describe a simulation algorithm for the evaluation of the probability of rejecting the null hypothesis at given treatment effect. We compare the blinded sample size re-estimation method with two unblinded methods with respect to the empirical type I error, the empirical power, and the empirical distribution of the standard deviation estimator and final sample size. We characterize the type I error inflation across the range of standardized non-inferiority margin for non-inferiority trials, and derive the adjusted significance level to ensure type I error control for given sample size of the internal pilot study. We show that the adjusted significance level increases as the sample size of the internal pilot study increases. Copyright © 2016 John Wiley & Sons, Ltd.
Farruggia, Piero; Di Cataldo, Andrea; Pinto, Rita M; Palmisani, Elena; Macaluso, Alessandra; Valvo, Laura Lo; Cantarini, Maria E; Tornesello, Assunta; Corti, Paola; Fioredda, Francesca; Varotto, Stefania; Martire, Baldo; Moroni, Isabella; Puccio, Giuseppe; Russo, Giovanna; Dufour, Carlo; Pillon, Marta
2016-01-01
Pearson syndrome (PS) is a very rare and often fatal multisystemic mitochondrial disorder involving the liver, kidney, pancreas, and hematopoietic and central nervous system. It is characterized principally by a transfusion-dependent anemia that usually improves over time, a tendency to develop severe infections, and a high mortality rate. We describe a group of 11 PS patients diagnosed in Italy in the period 1993-2014. The analysis of this reasonably sized cohort of patients contributes to the clinical profile of the disease and highlights a rough incidence of 1 case/million newborns. Furthermore, it seems that some biochemical parameters like increased serum alanine and urinary fumaric acid can help to address an early diagnosis.
Robustness analysis of bimodal networks in the whole range of degree correlation
NASA Astrophysics Data System (ADS)
Mizutaka, Shogo; Tanizawa, Toshihiro
2016-08-01
We present an exact analysis of the physical properties of bimodal networks specified by the two peak degree distribution fully incorporating the degree-degree correlation between node connections. The structure of the correlated bimodal network is uniquely determined by the Pearson coefficient of the degree correlation, keeping its degree distribution fixed. The percolation threshold and the giant component fraction of the correlated bimodal network are analytically calculated in the whole range of the Pearson coefficient from -1 to 1 against two major types of node removal, which are the random failure and the degree-based targeted attack. The Pearson coefficient for next-nearest-neighbor pairs is also calculated, which always takes a positive value even when the correlation between nearest-neighbor pairs is negative. From the results, it is confirmed that the percolation threshold is a monotonically decreasing function of the Pearson coefficient for the degrees of nearest-neighbor pairs increasing from -1 and 1 regardless of the types of node removal. In contrast, the node fraction of the giant component for bimodal networks with positive degree correlation rapidly decreases in the early stage of random failure, while that for bimodal networks with negative degree correlation remains relatively large until the removed node fraction reaches the threshold. In this sense, bimodal networks with negative degree correlation are more robust against random failure than those with positive degree correlation.
Robustness analysis of bimodal networks in the whole range of degree correlation.
Mizutaka, Shogo; Tanizawa, Toshihiro
2016-08-01
We present an exact analysis of the physical properties of bimodal networks specified by the two peak degree distribution fully incorporating the degree-degree correlation between node connections. The structure of the correlated bimodal network is uniquely determined by the Pearson coefficient of the degree correlation, keeping its degree distribution fixed. The percolation threshold and the giant component fraction of the correlated bimodal network are analytically calculated in the whole range of the Pearson coefficient from -1 to 1 against two major types of node removal, which are the random failure and the degree-based targeted attack. The Pearson coefficient for next-nearest-neighbor pairs is also calculated, which always takes a positive value even when the correlation between nearest-neighbor pairs is negative. From the results, it is confirmed that the percolation threshold is a monotonically decreasing function of the Pearson coefficient for the degrees of nearest-neighbor pairs increasing from -1 and 1 regardless of the types of node removal. In contrast, the node fraction of the giant component for bimodal networks with positive degree correlation rapidly decreases in the early stage of random failure, while that for bimodal networks with negative degree correlation remains relatively large until the removed node fraction reaches the threshold. In this sense, bimodal networks with negative degree correlation are more robust against random failure than those with positive degree correlation. PMID:27627318
Distance correlation methods for discovering associations in large astrophysical databases
Martínez-Gómez, Elizabeth; Richards, Mercedes T.; Richards, Donald St. P. E-mail: mrichards@astro.psu.edu
2014-01-20
High-dimensional, large-sample astrophysical databases of galaxy clusters, such as the Chandra Deep Field South COMBO-17 database, provide measurements on many variables for thousands of galaxies and a range of redshifts. Current understanding of galaxy formation and evolution rests sensitively on relationships between different astrophysical variables; hence an ability to detect and verify associations or correlations between variables is important in astrophysical research. In this paper, we apply a recently defined statistical measure called the distance correlation coefficient, which can be used to identify new associations and correlations between astrophysical variables. The distance correlation coefficient applies to variables of any dimension, can be used to determine smaller sets of variables that provide equivalent astrophysical information, is zero only when variables are independent, and is capable of detecting nonlinear associations that are undetectable by the classical Pearson correlation coefficient. Hence, the distance correlation coefficient provides more information than the Pearson coefficient. We analyze numerous pairs of variables in the COMBO-17 database with the distance correlation method and with the maximal information coefficient. We show that the Pearson coefficient can be estimated with higher accuracy from the corresponding distance correlation coefficient than from the maximal information coefficient. For given values of the Pearson coefficient, the distance correlation method has a greater ability than the maximal information coefficient to resolve astrophysical data into highly concentrated horseshoe- or V-shapes, which enhances classification and pattern identification. These results are observed over a range of redshifts beyond the local universe and for galaxies from elliptical to spiral.
Lee, Larissa J.; Sadow, Cheryl A.; Russell, Anthony; Viswanathan, Akila N.
2009-11-01
Purpose: To compare high dose rate (HDR) point B to pelvic lymph node dose using three-dimensional-planned brachytherapy for cervical cancer. Methods and Materials: Patients with FIGO Stage IB-IIIB cervical cancer received 70 tandem HDR applications using CT-based treatment planning. The obturator, external, and internal iliac lymph nodes (LN) were contoured. Per fraction (PF) and combined fraction (CF) right (R), left (L), and bilateral (Bil) nodal doses were analyzed. Point B dose was compared with LN dose-volume histogram (DVH) parameters by paired t test and Pearson correlation coefficients. Results: Mean PF and CF doses to point B were R 1.40 Gy +- 0.14 (CF: 7 Gy), L 1.43 +- 0.15 (CF: 7.15 Gy), and Bil 1.41 +- 0.15 (CF: 7.05 Gy). The correlation coefficients between point B and the D100, D90, D50, D2cc, D1cc, and D0.1cc LN were all less than 0.7. Only the D2cc to the obturator and the D0.1cc to the external iliac nodes were not significantly different from the point B dose. Significant differences between R and L nodal DVHs were seen, likely related to tandem deviation from irregular tumor anatomy. Conclusions: With HDR brachytherapy for cervical cancer, per fraction nodal dose approximates a dose equivalent to teletherapy. Point B is a poor surrogate for dose to specific nodal groups. Three-dimensional defined nodal contours during brachytherapy provide a more accurate reflection of delivered dose and should be part of comprehensive planning of the total dose to the pelvic nodes, particularly when there is evidence of pathologic involvement.
Yang, Pei-Lin; Huang, Guey-Shiun; Tsai, Chien-Sung; Lou, Meei-Fang
2015-01-01
Background Poor sleep quality is a common health problem for coronary artery bypass graft patients, however few studies have evaluated sleep quality during the period immediately following hospital discharge. Purpose The aim of this study was to investigate changes in sleep quality and emotional correlates in coronary artery bypass graft patients in Taiwan at 1 week and 1 month after hospital discharge. Methods We used a descriptive correlational design for this study. One week after discharge, 87 patients who had undergone coronary artery bypass surgery completed two structured questionnaires: the Pittsburgh Sleep Quality Index and the Hospital Anxiety and Depression Scale. Three weeks later (1 month after discharge) the patients completed the surveys again. Pearson correlations, t-tests, ANOVA and linear multiple regression analysis were used to analyze the data. Results A majority of the participants had poor sleep quality at 1 week (82.8%) and 1 month (66.7%) post-hospitalization, based on the global score of the Pittsburgh Sleep Quality Index. Despite poor sleep quality at both time-points the sleep quality at 1 month was significantly better than at 1-week post hospitalization. Poorer sleep quality correlated with older age, poorer heart function, anxiety and depression. The majority of participants had normal levels of anxiety at 1 week (69.0%) and 1 month (88.5%) as measured by the Hospital Anxiety and Depression Scale. However, some level of depression was seen at 1 week (78.1%) and 1 month (59.7%). Depression was a significant predictor of sleep quality at 1 week; at 1 month after hospital discharge both anxiety and depression were significant predictors of sleep quality. Conclusion Sleep quality, anxiety and depression all significantly improved 1 month after hospital discharge. However, more than half of the participants continued to have poor sleep quality and some level of depression. Health care personnel should be encouraged to assess sleep and
Hawke, Jesse L; Stallings, Michael C; Wadsworth, Sally J; DeFries, John C
2008-03-01
Although a comparison of concordance rates for deviant scores in identical and fraternal twin pairs can provide prima facie evidence for a genetic etiology, information is not fully utilized when continuous measures are analyzed in a dichotomous manner. Thus, DeFries and Fulker (Behav Genet 15:467-473, 1985; Acta Genet Med Gemellol, 37:205-216, 1988) developed a regression-based methodology (DF analysis) to assess genetic etiology in both selected and unselected twin samples. While the DF analysis is a very versatile and relatively powerful statistical approach, it is not easily extended to the multivariate case. In contrast, structural equation models may be readily extended to analyze multivariate data sets (Neale and Cardon, Methodology for genetic studies of twins and families, 1992). However, such methodologies may yield biased estimates of additive genetic, shared environmental, and non-shared environmental influences when multivariate models are fitted to selected twin data. Therefore, the Pearson-Aitken (PA) selection formula (Aitken, Proc Edinburgh Math Soc B, 4:106-110, 1934) was used to analyze reading performance data from twins with reading difficulties (selected sample) and a population of normally-achieving twin pairs (control sample). As a comparison, DF models were also fitted to these same data sets. In general, resulting estimates of additive genetic, shared environmental, and non-shared environmental influences were similar when the DF and PA models were fitted to the data. However, the PA selection formula may be more readily generalized to the multivariate case.
On the correlation of a naturally and an artificially dichotomized variable.
Ulrich, Rolf; Wirtz, Markus
2004-11-01
A method is suggested for estimating the correlation of a naturally (X) and an artificially (Y) dichotomized variable. It is assumed that a normal random variable (L) underlies the artificially dichotomized variable. The proposed correlation coefficient recovers the product moment correlation coefficient between X and L from a fourfold table of X and Y. The suggested correlation coefficient nu is contrasted with the phi correlation and the biserial eta. The biserial eta was proposed by Karl Pearson and is conceptually related to the new correlation coefficient. However, in addition, Pearson's biserial eta invokes the assumption that the marginal distribution of L is normal, which contradicts its basic assumptions and thus does not recover the true correlation of L and X. Finally, an approximation is provided to simplify the calculation of nu and its standard error. PMID:15511306
Bhagavatula, Indira Devi; Bhat, Dhananjaya I; Sasidharan, Gopalakrishnan M; Mishra, Rakesh Kumar; Maste, Praful Suresh; Vilanilam, George C; Sathyaprabha, Talakkad N
2016-06-01
OBJECTIVE Respiratory abnormalities are well documented in acute spinal cord injury; however, the literature available for respiratory dysfunction in chronic compressive myelopathy (CCM) is limited. Respiratory dysfunction in CCM is often subtle and subclinical. The authors studied the pattern of respiratory dysfunction in patients with chronic cord compression by using spirometry, and the clinical and surgical implications of this dysfunction. In this study they also attempted to address the postoperative respiratory function in these patients. METHODS A prospective study was done in 30 patients in whom cervical CCM due to either cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) was diagnosed. Thirty age-matched healthy volunteers were recruited as controls. None of the patients included in the study had any symptoms or signs of respiratory dysfunction. After clinical and radiological diagnosis, all patients underwent pulmonary function tests (PFTs) performed using a standardized Spirometry Kit Micro before and after surgery. The data were analyzed using Statistical Software SPSS version 13.0. Comparison between the 2 groups was done using the Student t-test. The Pearson correlation coefficient was used for PFT results and Nurick classification scores. A p value < 0.05 was considered significant. RESULTS Cervical spondylotic myelopathy (prolapsed intervertebral disc) was the predominant cause of compression (n = 21, 70%) followed by OPLL (n = 9, 30%). The average patient age was 45.06 years. Degenerative cervical spine disease has a relatively younger onset in the Indian population. The majority of the patients (n = 28, 93.3%) had compression at or above the C-5 level. Ten patients (33.3%) underwent an anterior approach and discectomy, 11 patients (36.7%) underwent decompressive laminectomy, and the remaining 9 underwent either corpectomy with fusion or laminoplasty. The mean preoperative forced vital capacity (FVC) (65%) of the
Bhagavatula, Indira Devi; Bhat, Dhananjaya I; Sasidharan, Gopalakrishnan M; Mishra, Rakesh Kumar; Maste, Praful Suresh; Vilanilam, George C; Sathyaprabha, Talakkad N
2016-06-01
OBJECTIVE Respiratory abnormalities are well documented in acute spinal cord injury; however, the literature available for respiratory dysfunction in chronic compressive myelopathy (CCM) is limited. Respiratory dysfunction in CCM is often subtle and subclinical. The authors studied the pattern of respiratory dysfunction in patients with chronic cord compression by using spirometry, and the clinical and surgical implications of this dysfunction. In this study they also attempted to address the postoperative respiratory function in these patients. METHODS A prospective study was done in 30 patients in whom cervical CCM due to either cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL) was diagnosed. Thirty age-matched healthy volunteers were recruited as controls. None of the patients included in the study had any symptoms or signs of respiratory dysfunction. After clinical and radiological diagnosis, all patients underwent pulmonary function tests (PFTs) performed using a standardized Spirometry Kit Micro before and after surgery. The data were analyzed using Statistical Software SPSS version 13.0. Comparison between the 2 groups was done using the Student t-test. The Pearson correlation coefficient was used for PFT results and Nurick classification scores. A p value < 0.05 was considered significant. RESULTS Cervical spondylotic myelopathy (prolapsed intervertebral disc) was the predominant cause of compression (n = 21, 70%) followed by OPLL (n = 9, 30%). The average patient age was 45.06 years. Degenerative cervical spine disease has a relatively younger onset in the Indian population. The majority of the patients (n = 28, 93.3%) had compression at or above the C-5 level. Ten patients (33.3%) underwent an anterior approach and discectomy, 11 patients (36.7%) underwent decompressive laminectomy, and the remaining 9 underwent either corpectomy with fusion or laminoplasty. The mean preoperative forced vital capacity (FVC) (65%) of the
Correlating Species and Spectral Diversity using Remote Sensing in Successional Fields in Virginia
NASA Astrophysics Data System (ADS)
Aneece, I.; Epstein, H. E.
2015-12-01
Conserving biodiversity can help preserve ecosystem properties and function. As the increasing prevalence of invasive plant species threatens biodiversity, advances in remote sensing technology can help monitor invasive species and their effects on ecosystems and plant communities. To assess whether we could study the effects of invasive species on biodiversity using remote sensing, we asked whether species diversity was positively correlated with spectral diversity, and whether correlations differed among spectral regions along the visible and near-infrared range. To answer these questions, we established community plots in secondary successional fields at the Blandy Experimental Farm in northern Virginia and collected vegetation surveys and ground-level hyperspectral data from 350 to 1025 nm wavelengths. Pearson correlation analysis revealed a positive correlation between spectral diversity and species diversity in the visible ranges of 350-499 nm (Pearson correlation=0.69, p=0.01), 500-589 nm (Pearson=0.64, p=0.03), and 590-674 nm (Pearson=0.70, p=0.01), slight positive correlation in the red edge range of 675-754 nm (Pearson=0.56, p=0.06), and no correlation in the near-infrared ranges of 755-924 nm (Pearson=-0.06, p=0.85) and 925-1025 nm (Pearson=0.30, p=0.34). These differences in correlations across spectral regions may be due to the elements that contribute to signatures in those regions and spectral data transformation methods. To investigate the role of pigment variability in these correlations, we estimated chlorophyll, carotenoid, and anthocyanin concentrations of five dominant species in the plots using vegetation indices. Although interspecific variability in pigment levels exceeded intraspecific variability, chlorophyll (F value=118) was more varied within species than carotenoids (F=322) and anthocyanins (F=126), perhaps contributing to the lack of correlation between species diversity and spectral diversity in the red edge region. Interspecific
ERIC Educational Resources Information Center
Dickens, Rachel H.; Meisinger, Elizabeth B.; Tarar, Jessica M.
2015-01-01
The Comprehensive Test of Phonological Processing-Second Edition (CTOPP-2; Wagner, Torgesen, Rashotte, & Pearson, 2013) is a norm-referenced test that measures phonological processing skills related to reading for individuals aged 4 to 24. According to its authors, the CTOPP-2 may be used to identify individuals who are markedly below their…
Bayesian Correlation Analysis for Sequence Count Data
Lau, Nelson; Perkins, Theodore J.
2016-01-01
Evaluating the similarity of different measured variables is a fundamental task of statistics, and a key part of many bioinformatics algorithms. Here we propose a Bayesian scheme for estimating the correlation between different entities’ measurements based on high-throughput sequencing data. These entities could be different genes or miRNAs whose expression is measured by RNA-seq, different transcription factors or histone marks whose expression is measured by ChIP-seq, or even combinations of different types of entities. Our Bayesian formulation accounts for both measured signal levels and uncertainty in those levels, due to varying sequencing depth in different experiments and to varying absolute levels of individual entities, both of which affect the precision of the measurements. In comparison with a traditional Pearson correlation analysis, we show that our Bayesian correlation analysis retains high correlations when measurement confidence is high, but suppresses correlations when measurement confidence is low—especially for entities with low signal levels. In addition, we consider the influence of priors on the Bayesian correlation estimate. Perhaps surprisingly, we show that naive, uniform priors on entities’ signal levels can lead to highly biased correlation estimates, particularly when different experiments have widely varying sequencing depths. However, we propose two alternative priors that provably mitigate this problem. We also prove that, like traditional Pearson correlation, our Bayesian correlation calculation constitutes a kernel in the machine learning sense, and thus can be used as a similarity measure in any kernel-based machine learning algorithm. We demonstrate our approach on two RNA-seq datasets and one miRNA-seq dataset. PMID:27701449
Geerligs, Linda; Cam-Can; Henson, Richard N
2016-07-15
Studies of brain-wide functional connectivity or structural covariance typically use measures like the Pearson correlation coefficient, applied to data that have been averaged across voxels within regions of interest (ROIs). However, averaging across voxels may result in biased connectivity estimates when there is inhomogeneity within those ROIs, e.g., sub-regions that exhibit different patterns of functional connectivity or structural covariance. Here, we propose a new measure based on "distance correlation"; a test of multivariate dependence of high dimensional vectors, which allows for both linear and non-linear dependencies. We used simulations to show how distance correlation out-performs Pearson correlation in the face of inhomogeneous ROIs. To evaluate this new measure on real data, we use resting-state fMRI scans and T1 structural scans from 2 sessions on each of 214 participants from the Cambridge Centre for Ageing & Neuroscience (Cam-CAN) project. Pearson correlation and distance correlation showed similar average connectivity patterns, for both functional connectivity and structural covariance. Nevertheless, distance correlation was shown to be 1) more reliable across sessions, 2) more similar across participants, and 3) more robust to different sets of ROIs. Moreover, we found that the similarity between functional connectivity and structural covariance estimates was higher for distance correlation compared to Pearson correlation. We also explored the relative effects of different preprocessing options and motion artefacts on functional connectivity. Because distance correlation is easy to implement and fast to compute, it is a promising alternative to Pearson correlations for investigating ROI-based brain-wide connectivity patterns, for functional as well as structural data.
Quantifying meta-correlations in financial markets
NASA Astrophysics Data System (ADS)
Kenett, Dror Y.; Preis, Tobias; Gur-Gershgoren, Gitit; Ben-Jacob, Eshel
2012-08-01
Financial markets are modular multi-level systems, in which the relationships between the individual components are not constant in time. Sudden changes in these relationships significantly affect the stability of the entire system, and vice versa. Our analysis is based on historical daily closing prices of the 30 components of the Dow Jones Industrial Average (DJIA) from March 15th, 1939 until December 31st, 2010. We quantify the correlation among these components by determining Pearson correlation coefficients, to investigate whether mean correlation of the entire portfolio can be used as a precursor for changes in the index return. To this end, we quantify the meta-correlation - the correlation of mean correlation and index return. We find that changes in index returns are significantly correlated with changes in mean correlation. Furthermore, we study the relationship between the index return and correlation volatility - the standard deviation of correlations for a given time interval. This parameter provides further evidence of the effect of the index on market correlations and their fluctuations. Our empirical findings provide new information and quantification of the index leverage effect, and have implications to risk management, portfolio optimization, and to the increased stability of financial markets.
The Social Correlates of Lexical Borrowing in Spanish in New York City
ERIC Educational Resources Information Center
Varra, Rachel Marie
2013-01-01
This dissertation investigates lexical borrowing in Spanish in New York. English-origin lexical material was extracted from a stratified sample of 146 Spanish-speaking informants of different ages, national origins, classes, etc., living in New York City. ANOVAs and Pearson correlations determined whether lexical borrowing frequency and the type…
Why Waveform Correlation Sometimes Fails
NASA Astrophysics Data System (ADS)
Carmichael, J.
2015-12-01
the Neyman Pearson criteria. Bottom: The histogram of the correlation statistic time series (gray) superimposed on the theoretical null distribution (black curve). The line shows the threshold, consistent with a right-tail probability, computed from the black curve.
Babchishin, Kelly M; Helmus, Leslie-Maaike
2016-09-01
Correlations are the simplest and most commonly understood effect size statistic in psychology. The purpose of the current paper was to use a large sample of real-world data (109 correlations with 60,415 participants) to illustrate the base rate dependence of correlations when applied to dichotomous or ordinal data. Specifically, we examined the influence of the base rate on different effect size metrics. Correlations decreased when the dichotomous variable did not have a 50 % base rate. The higher the deviation from a 50 % base rate, the smaller the observed Pearson's point-biserial and Kendall's tau correlation coefficients. In contrast, the relationship between base rate deviations and the more commonly proposed alternatives (i.e., polychoric correlation coefficients, AUCs, Pearson/Thorndike adjusted correlations, and Cohen's d) were less remarkable, with AUCs being most robust to attenuation due to base rates. In other words, the base rate makes a marked difference in the magnitude of the correlation. As such, when using dichotomous data, the correlation may be more sensitive to base rates than is optimal for the researcher's goals. Given the magnitude of the association between the base rate and point-biserial correlations (r = -.81) and Kendall's tau (r = -.80), we recommend that AUCs, Pearson/Thorndike adjusted correlations, Cohen's d, or polychoric correlations should be considered as alternate effect size statistics in many contexts. PMID:26182856
A robust measure of correlation between two genes on a microarray
Hardin, Johanna; Mitani, Aya; Hicks, Leanne; VanKoten, Brian
2007-01-01
Background The underlying goal of microarray experiments is to identify gene expression patterns across different experimental conditions. Genes that are contained in a particular pathway or that respond similarly to experimental conditions could be co-expressed and show similar patterns of expression on a microarray. Using any of a variety of clustering methods or gene network analyses we can partition genes of interest into groups, clusters, or modules based on measures of similarity. Typically, Pearson correlation is used to measure distance (or similarity) before implementing a clustering algorithm. Pearson correlation is quite susceptible to outliers, however, an unfortunate characteristic when dealing with microarray data (well known to be typically quite noisy.) Results We propose a resistant similarity metric based on Tukey's biweight estimate of multivariate scale and location. The resistant metric is simply the correlation obtained from a resistant covariance matrix of scale. We give results which demonstrate that our correlation metric is much more resistant than the Pearson correlation while being more efficient than other nonparametric measures of correlation (e.g., Spearman correlation.) Additionally, our method gives a systematic gene flagging procedure which is useful when dealing with large amounts of noisy data. Conclusion When dealing with microarray data, which are known to be quite noisy, robust methods should be used. Specifically, robust distances, including the biweight correlation, should be used in clustering and gene network analysis. PMID:17592643
Cross correlations among estimators of shape
NASA Astrophysics Data System (ADS)
Martins, Eduardo S.; Stedinger, Jery R.
2002-11-01
The regional variability of shape parameters (such as κ for the GEV distribution) may be described by generalized least squares (GLS) regression models that allow shape parameters to be estimated from basin characteristics recognizing the sampling uncertainty in available shape estimators. Implementation of such GLS models requires estimates of the cross-site correlation of the shape parameter estimators for every pair of sites. Monte Carlo experiments provided the information needed to identify simple power approximations of the relationships between the cross correlation of estimators of skewness γ from [log] Pearson type 3 (P3) data and of the shape parameter κ of both generalized Pareto (GP) and generalized extreme value (GEV) distributions, as functions of the intersite correlation of concurrent flows.
Golband, Farnoosh; Hosseini, Agha Fatemeh; Mojtahedzadeh, Rita; Mirhosseini, Fakhrossadat; Bigdeli, Shoaleh
2014-01-01
E-learning as an educational approach has been adopted by diverse educational and academic centers worldwide as it facilitates learning in facing the challenges of the new era in education. Considering the significance of virtual education and its growing practice, it is of vital importance to examine its components for promoting and maintaining success. This analytical cross-sectional study was an attempt to determine the relationship between four factors of content, educator, learner and system, and effective e-learning in terms of demographic variables, including age, gender, educational background, and marital status of postgraduate master's students (MSc) studying at virtual faculty of Tehran University of Medical Sciences. The sample was selected by census (n=60); a demographic data gathering tool and a researcher-made questionnaire were used to collect data. The face and content validity of both tools were confirmed and the results were analyzed by descriptive statistics (frequency, percentile, standard deviation and mean) and inferential statistics (independent t-test, Scheffe's test, one-way ANOVA and Pearson correlation test) by using SPSS (V.16). The present study revealed that There was no statistically significant relationship between age and marital status and effective e-learning (P>0.05); whereas, there was a statistically significant difference between gender and educational background with effective e-learning (P<0.05). Knowing the extent to which these factors can influence effective e-learning can help managers and designers to make the right decisions about educational components of e-learning, i.e. content, educator, system and learner and improve them to create a more productive learning environment for learners.
Golband, Farnoosh; Hosseini, Agha Fatemeh; Mojtahedzadeh, Rita; Mirhosseini, Fakhrossadat; Bigdeli, Shoaleh
2014-01-01
E-learning as an educational approach has been adopted by diverse educational and academic centers worldwide as it facilitates learning in facing the challenges of the new era in education. Considering the significance of virtual education and its growing practice, it is of vital importance to examine its components for promoting and maintaining success. This analytical cross-sectional study was an attempt to determine the relationship between four factors of content, educator, learner and system, and effective e-learning in terms of demographic variables, including age, gender, educational background, and marital status of postgraduate master's students (MSc) studying at virtual faculty of Tehran University of Medical Sciences. The sample was selected by census (n=60); a demographic data gathering tool and a researcher-made questionnaire were used to collect data. The face and content validity of both tools were confirmed and the results were analyzed by descriptive statistics (frequency, percentile, standard deviation and mean) and inferential statistics (independent t-test, Scheffe's test, one-way ANOVA and Pearson correlation test) by using SPSS (V.16). The present study revealed that There was no statistically significant relationship between age and marital status and effective e-learning (P>0.05); whereas, there was a statistically significant difference between gender and educational background with effective e-learning (P<0.05). Knowing the extent to which these factors can influence effective e-learning can help managers and designers to make the right decisions about educational components of e-learning, i.e. content, educator, system and learner and improve them to create a more productive learning environment for learners. PMID:25415821
Asymmetric correlation matrices: an analysis of financial data
NASA Astrophysics Data System (ADS)
Livan, G.; Rebecchi, L.
2012-06-01
We analyse the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non-symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrix to distinguish between noise and non-trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non-symmetric correlation matrix. We find several non trivial results when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.
Cruz, A D; Esteves, R G; Poiate, I A V P; Portero, P P; Almeida, S M
2014-01-01
This study aimed to objectively evaluate the radiopacity of different dental composites and their subjective influence on diagnosing secondary caries-like lesions and how these results correlate. For objective analysis, three resin specimens (1 mm thick, with a 4-mm internal diameter) were made with four composites: 1) Charisma; 2) Filtek Z250; 3) Prisma AP.H; and 4) Glacier. Three human teeth were selected and then mesio-distally sectioned (1 mm thick) to make the dental specimens. An aluminum (Al) wedge (12 steps, 1 mm thick, 99.8% purity) was used as an internal standard to calculate the radiopacity. For subjective analysis, 20 human teeth were selected and then prepared with a mesio-occluso-distal (MOD) inlay cavity, with half the teeth receiving a round cavity to simulate the carious lesion. The MOD was restored using the composites at four different times. Standardized radiographs were acquired and then digitized (300 dpi and eight-bit TIFF) for both analyses. A histogram objectively measured the pixel intensity values of the images, which were converted into millimeters of Al using linear regressions. Eight observers subjectively evaluated the images using a five-point rating scale to diagnose the caries. The data were statistically analyzed using the Student t-test, the Kappa test, diagnostic testing, and the Pearson correlation coefficient (α=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
On the insignificance of Herschel's sunspot correlation
Love, Jeffrey J.
2013-01-01
We examine William Herschel's hypothesis that solar-cycle variation of the Sun's irradiance has a modulating effect on the Earth's climate and that this is, specifically, manifested as an anticorrelation between sunspot number and the market price of wheat. Since Herschel first proposed his hypothesis in 1801, it has been regarded with both interest and skepticism. Recently, reports have been published that either support Herschel's hypothesis or rely on its validity. As a test of Herschel's hypothesis, we seek to reject a null hypothesis of a statistically random correlation between historical sunspot numbers, wheat prices in London and the United States, and wheat farm yields in the United States. We employ binary-correlation, Pearson-correlation, and frequency-domain methods. We test our methods using a historical geomagnetic activity index, well known to be causally correlated with sunspot number. As expected, the measured correlation between sunspot number and geomagnetic activity would be an unlikely realization of random data; the correlation is “statistically significant.” On the other hand, measured correlations between sunspot number and wheat price and wheat yield data would be very likely realizations of random data; these correlations are “insignificant.” Therefore, Herschel's hypothesis must be regarded with skepticism. We compare and contrast our results with those of other researchers. We discuss procedures for evaluating hypotheses that are formulated from historical data.
On degree-degree correlations in multilayer networks
NASA Astrophysics Data System (ADS)
de Arruda, Guilherme Ferraz; Cozzo, Emanuele; Moreno, Yamir; Rodrigues, Francisco A.
2016-06-01
We propose a generalization of the concept of assortativity based on the tensorial representation of multilayer networks, covering the definitions given in terms of Pearson and Spearman coefficients. Our approach can also be applied to weighted networks and provides information about correlations considering pairs of layers. By analyzing the multilayer representation of the airport transportation network, we show that contrasting results are obtained when the layers are analyzed independently or as an interconnected system. Finally, we study the impact of the level of assortativity and heterogeneity between layers on the spreading of diseases. Our results highlight the need of studying degree-degree correlations on multilayer systems, instead of on aggregated networks.
Giraud, B G; Heumann, J M; Lapedes, A S
1999-05-01
The fact that correlation does not imply causation is well known. Correlation between variables at two sites does not imply that the two sites directly interact, because, e.g., correlation between distant sites may be induced by chaining of correlation between a set of intervening, directly interacting sites. Such "noncausal correlation" is well understood in statistical physics: an example is long-range order in spin systems, where spins which have only short-range direct interactions, e.g., the Ising model, display correlation at a distance. It is less well recognized that such long-range "noncausal" correlations can in fact be stronger than the magnitude of any causal correlation induced by direct interactions. We call this phenomenon superadditive correlation (SAC). We demonstrate this counterintuitive phenomenon by explicit examples in (i) a model spin system and (ii) a model continuous variable system, where both models are such that two variables have multiple intervening pathways of indirect interaction. We apply the technique known as decimation to explain SAC as an additive, constructive interference phenomenon between the multiple pathways of indirect interaction. We also explain the effect using a definition of the collective mode describing the intervening spin variables. Finally, we show that the SAC effect is mirrored in information theory, and is true for mutual information measures in addition to correlation measures. Generic complex systems typically exhibit multiple pathways of indirect interaction, making SAC a potentially widespread phenomenon. This affects, e.g., attempts to deduce interactions by examination of correlations, as well as, e.g., hierarchical approximation methods for multivariate probability distributions, which introduce parameters based on successive orders of correlation. PMID:11969452
DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.
2012-01-01
Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sites––the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCS––to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1–4.2 ka and had 0.6–2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 ± 0.3 ka and 3.5 ± 0.3 ka, with an average displacement per event of 1.9–2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 ± 0.04 ka and had 0.1–0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1–2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weber–Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our
Baek, Seung-A; Jung, Young-Ho; Lim, Sun-Hyung; Park, Sang Un; Kim, Jae Kwang
2016-06-01
A total of 38 bioactive compounds, including glucosinolates, carotenoids, tocopherols, sterols, and policosanols, were characterized from nine varieties of Chinese cabbage (Brassica rapa L. subsp. pekinensis) to determine their phytochemical diversity and analyze their abundance relationships. The metabolite profiles were evaluated with principal component analysis (PCA), Pearson correlation analysis, and hierarchical clustering analysis (HCA). PCA and HCA identified two distinct varieties of Chinese cabbage (Cheonsangcheonha and Waldongcheonha) with higher levels of glucosinolates and carotenoids. Pairwise comparisons of the 38 metabolites were calculated using Pearson correlation coefficients. The HCA, which used the correlation coefficients, clustered metabolites that are derived from closely related biochemical pathways. Significant correlations were discovered between chlorophyll and carotenoids. Additionally, aliphatic glucosinolate and carotenoid levels were positively correlated. The Cheonsangcheonha and Waldongcheonha varieties appear to be good candidates for breeding because they have high glucosinolate and carotenoid levels. PMID:27172980
Baek, Seung-A; Jung, Young-Ho; Lim, Sun-Hyung; Park, Sang Un; Kim, Jae Kwang
2016-06-01
A total of 38 bioactive compounds, including glucosinolates, carotenoids, tocopherols, sterols, and policosanols, were characterized from nine varieties of Chinese cabbage (Brassica rapa L. subsp. pekinensis) to determine their phytochemical diversity and analyze their abundance relationships. The metabolite profiles were evaluated with principal component analysis (PCA), Pearson correlation analysis, and hierarchical clustering analysis (HCA). PCA and HCA identified two distinct varieties of Chinese cabbage (Cheonsangcheonha and Waldongcheonha) with higher levels of glucosinolates and carotenoids. Pairwise comparisons of the 38 metabolites were calculated using Pearson correlation coefficients. The HCA, which used the correlation coefficients, clustered metabolites that are derived from closely related biochemical pathways. Significant correlations were discovered between chlorophyll and carotenoids. Additionally, aliphatic glucosinolate and carotenoid levels were positively correlated. The Cheonsangcheonha and Waldongcheonha varieties appear to be good candidates for breeding because they have high glucosinolate and carotenoid levels.
NASA Astrophysics Data System (ADS)
Kmetz, Barbara Fotta
2001-07-01
This study sought to identify factors that could be used to predict the success of students on the science portion of the grade ten Connecticut Academic Performance Test (CAPT). While the Connecticut State Department of Education measures student achievement in mathematics, reading and writing in grades 4, 6, and 8, science is assessed only in the grade ten CAPT. Since the CAPT science test does not identify specific areas in need of improvement, it is not possible to determine causes for low test scores. To address this, the study investigated the predictive values of the grade eight Mastery Tests in mathematics and reading, the student ability scores of the Otis-Lennon School Ability Index, and grades in prior science courses. The research sample consisted of five hundred and twenty-five students, member of the graduating classes of 2000 and 2001 in a large suburban high school. Students in the study had participated in the district testing program and their scores for the grade seven Otis-Lennon School Ability Test (OLSAT), the grade eight Connecticut Mastery Tests (CMT) and the grade ten Connecticut Academic Performance Tests (CAPT) were available for analysis. This study investigated correlations between student achievement on the CMT and the science subtest of the CAPT, between OLSAT scores and the CAPT science scores, and between grades in ninth grade science and CAPT science scores. Scores were disaggregated by gender and by course level. Hypotheses 1, 2, 3 and 4 investigated the Pearson Product Moment Correlations of the OLSAT, CMT and course grades with scores on the science portion of the CAPT. Hypothesis 5 compared the scores of male and female students, using the t-test of independent sample means. Calculations showed moderate correlations for hypotheses 1--4, and the hypotheses were accepted. Hypothesis 5 was accepted for one class and rejected for the other. On the whole, female students received higher course grades and lower standardized test
Akdemir, Nermin; Cinemre, Fatma Behice; Bostancı, Mehmet Sühha; Cinemre, Hakan; Ünal, Orhan; Ozden, Selçuk; Cevrioglu, Arif Serhan; Kacal, Zubeyde; Akdemir, Ramazan
2016-08-01
In this study, we aimed to investigate the association of serum asymmetric dimethylarginine (ADMA) and anti-Müllerian hormone (AMH) levels in primary dysmenorrhea patients. The study employed a cross-sectional design. Eighty-nine female university students with primary dysmenorrhea were included in the study. All patients underwent complete clinical and laboratory investigations, including serum ADMA, AMH levels, pelvic ultrasonography, electrocardiography, and echocardiography. Pearson correlation and linear regression analysis were used to evaluate associations between continuous data. Categorical associations were evaluated using χ(2) test. Correlation analysis between serum ADMA and AMH levels in the study group showed a highly significant positive relationship (Pearson correlation = 0.978, p = 0.01). Our study has shown a significant positive correlation between serum ADMA and AMH levels in primary dysmenorrhea. Serum ADMA levels may have the potential to demonstrate ovarian reserve. PMID:27523455
Gene differential coexpression analysis based on biweight correlation and maximum clique.
Zheng, Chun-Hou; Yuan, Lin; Sha, Wen; Sun, Zhan-Li
2014-01-01
Differential coexpression analysis usually requires the definition of 'distance' or 'similarity' between measured datasets. Until now, the most common choice is Pearson correlation coefficient. However, Pearson correlation coefficient is sensitive to outliers. Biweight midcorrelation is considered to be a good alternative to Pearson correlation since it is more robust to outliers. In this paper, we introduce to use Biweight Midcorrelation to measure 'similarity' between gene expression profiles, and provide a new approach for gene differential coexpression analysis. Firstly, we calculate the biweight midcorrelation coefficients between all gene pairs. Then, we filter out non-informative correlation pairs using the 'half-thresholding' strategy and calculate the differential coexpression value of gene, The experimental results on simulated data show that the new approach performed better than three previously published differential coexpression analysis (DCEA) methods. Moreover, we use the maximum clique analysis to gene subset included genes identified by our approach and previously reported T2D-related genes, many additional discoveries can be found through our method.
Richards, Joseph M.; Johnson, Byron Thomas
2002-01-01
The chemistry and toxicity of base flow and urban stormwater were characterized to determine if urban stormwater was degrading the water quality of the Pearson Creek and Wilsons Creek Basins in and near the city of Springfield, Greene County, Missouri. Potentially toxic components of stormwater (nutrients, trace metals, and organic compounds) were identified to help resource managers identify and minimize the sources of toxicants. Nutrient loading to the James River from these two basins (especially the Wilsons Creek Basin) is of some concern because of the potential to degrade downstream water quality. Toxicity related to dissolved trace metal constituents in stormwater does not appear to be a great concern in these two basins. Increased heterotrophic activity, the result of large densities of fecal indicator bacteria introduced into the streams after storm events, could lead to associated dissolved oxygen stress of native biota. Analysis of stormwater samples detected a greater number of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) than were present in base-flow samples. The number and concentrations of pesticides detected in both the base-flow and stormwater samples were similar.Genotoxicity tests were performed to determine the bioavilability of chemical contaminants and determine the potential harmful effects on aquatic biota of Pearson Creek and Wilsons Creek. Genotoxicity was determined from dialysates from both long-term (approximately 30 days) and storm-event (3 to 5 days) semipermeable membrane device (SPMD) samples that were collected in each basin. Toxicity tests of SPMD samples indicated evidence of genotoxins in all SPMD samples. Hepatic activity assessment of one long-term SPMD sample indicated evidence of contaminant uptake in fish. Chemical analyses of the SPMD samples found that relatively few pesticides and pesticide metabolites had been sequestered in the lipid material of the SPMD; however, numerous PAHs and
Correlations among ambiguous figures, curiosity, and spatial ability.
Beer, J
1990-12-01
For 29 college students (6 men, 23 women) who passively viewed in each of 6 blocks both the Schroeder stair and the Necker cube for 3 min. apiece with one 3-min. rest between viewings, their frequency of reversals, sex, GPA, scores on the Wechsler Adult Intelligence Scale Information subtest, the two-dimensional Test 8, and the three-dimensional Test 9 of the Multiple Aptitude Test, measuring spatial ability, and three curiosity measures--the Which-to-Discuss Test, the Maze test, and the Ontario Test of Intrinsic Motivation--were not significantly correlated by Pearson's method with the number of ambiguous figure reversals.
Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.
2014-01-01
Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640
NASA Astrophysics Data System (ADS)
Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.
2014-04-01
Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques.
Gates, Pearson Partner on Common Core
ERIC Educational Resources Information Center
Gewertz, Catherine
2011-01-01
As states and school districts grapple with how to teach the skills outlined in the new common standards, two foundations have announced a partnership aimed at crafting complete, online curricula for those standards in mathematics and English/language arts that span nearly every year of a child's precollegiate education. The announcement last…
Correlates of Frailty Among Homeless Adults
Salem, Benissa E.; Nyamathi, Adeline M.; Brecht, Mary-Lynn; Phillips, Linda R.; Mentes, Janet C.; Sarkisian, Catherine; Leake, Barbara
2013-01-01
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. PMID:23676627
Temporal Correlations of the Running Maximum of a Brownian Trajectory
NASA Astrophysics Data System (ADS)
Bénichou, Olivier; Krapivsky, P. L.; Mejía-Monasterio, Carlos; Oshanin, Gleb
2016-08-01
We study the correlations between the maxima m and M of a Brownian motion (BM) on the time intervals [0 ,t1] and [0 ,t2], with t2>t1. We determine the exact forms of the distribution functions P (m ,M ) and P (G =M -m ), and calculate the moments E {(M-m ) k} and the cross-moments E {mlMk} with arbitrary integers l and k . We show that correlations between m and M decay as √{t1/t2 } when t2/t1→∞ , revealing strong memory effects in the statistics of the BM maxima. We also compute the Pearson correlation coefficient ρ (m ,M ) and the power spectrum of Mt, and we discuss a possibility of extracting the ensemble-averaged diffusion coefficient in single-trajectory experiments using a single realization of the maximum process.
Temporal Correlations of the Running Maximum of a Brownian Trajectory.
Bénichou, Olivier; Krapivsky, P L; Mejía-Monasterio, Carlos; Oshanin, Gleb
2016-08-19
We study the correlations between the maxima m and M of a Brownian motion (BM) on the time intervals [0,t_{1}] and [0,t_{2}], with t_{2}>t_{1}. We determine the exact forms of the distribution functions P(m,M) and P(G=M-m), and calculate the moments E{(M-m)^{k}} and the cross-moments E{m^{l}M^{k}} with arbitrary integers l and k. We show that correlations between m and M decay as sqrt[t_{1}/t_{2}] when t_{2}/t_{1}→∞, revealing strong memory effects in the statistics of the BM maxima. We also compute the Pearson correlation coefficient ρ(m,M) and the power spectrum of M_{t}, and we discuss a possibility of extracting the ensemble-averaged diffusion coefficient in single-trajectory experiments using a single realization of the maximum process. PMID:27588841
Loussert Fonta, Céline; Humbel, Bruno M
2015-09-01
In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array
Sinclair, Michael B.; Pfeifer, Kent B.; Flemming, Jeb H.; Jones, Gary D.; Tigges, Chris P.
2010-04-13
A correlation spectrometer can detect a large number of gaseous compounds, or chemical species, with a species-specific mask wheel. In this mode, the spectrometer is optimized for the direct measurement of individual target compounds. Additionally, the spectrometer can measure the transmission spectrum from a given sample of gas. In this mode, infrared light is passed through a gas sample and the infrared transmission signature of the gasses present is recorded and measured using Hadamard encoding techniques. The spectrometer can detect the transmission or emission spectra in any system where multiple species are present in a generally known volume.
Loussert Fonta, Céline; Humbel, Bruno M
2015-09-01
In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array
Correlation between three color coordinates of human teeth.
Lee, Yong-Keun
2014-11-01
The objective was to determine whether there were significant correlations in the three color coordinates within each of two color coordinate systems, such as the Commission Internationale de l’Eclairage (CIE) L*a*b* system, and the lightness, chroma, and hue angle system, of human vital teeth. The color of six maxillary and six mandibular anterior teeth was measured by the Shade Vision System. Pearson correlations between each pair of the color coordinates were determined (α=0.01 ). The influence of two color coordinates on the other color coordinate was determined with a multiple regression analysis (α=0.01 ). Based on correlation analyses, all the color coordinate pairs showed significant correlations except for the chroma and hue angle pair. The CIE L* was negatively correlated with the CIE a*,b*, and chroma, but positively correlated with the hue angle. The CIE a* was positively correlated with the CIE b* and chroma. Tooth color coordinates were correlated each other. Lighter teeth were less chromatic both in the CIE a* and b* coordinates. Therefore, it was postulated that the three color coordinates of human teeth were harmonized within certain color attribute ranges, and a lack of correlations in these coordinates might indicate external/internal discolorations and/or anomalies of teeth.
Estimating membrane voltage correlations from extracellular spike trains.
Dorn, Jessy D; Ringach, Dario L
2003-04-01
The cross-correlation coefficient between neural spike trains is a commonly used tool in the study of neural interactions. Two well-known complications that arise in its interpretation are 1) modulations in the correlation coefficient may result solely from changes in the mean firing rate of the cells and 2) the mean firing rates of the neurons impose upper and lower bounds on the correlation coefficient whose absolute values differ by an order of magnitude or more. Here, we propose a model-based approach to the interpretation of spike train correlations that circumvents these problems. The basic idea of our proposal is to estimate the cross-correlation coefficient between the membrane voltages of two cells from their extracellular spike trains and use the resulting value as the degree of correlation (or association) of neural activity. This is done in the context of a model that assumes the membrane voltages of the cells have a joint normal distribution and spikes are generated by a simple thresholding operation. We show that, under these assumptions, the estimation of the correlation coefficient between the membrane voltages reduces to the calculation of a tetrachoric correlation coefficient (a measure of association in nominal data introduced by Karl Pearson) on a contingency table calculated from the spike data. Simulations of conductance-based leaky integrate-and-fire neurons indicate that, despite its simplicity, the technique yields very good estimates of the intracellular membrane voltage correlation from the extracellular spike trains in biologically realistic models. PMID:12686584
Gesualdo, Francesco; Stilo, Giovanni; D'Ambrosio, Angelo; Carloni, Emanuela; Pandolfi, Elisabetta; Velardi, Paola; Fiocchi, Alessandro; Tozzi, Alberto E
2015-01-01
Pollen forecasts are in use everywhere to inform therapeutic decisions for patients with allergic rhinoconjunctivitis (ARC). We exploited data derived from Twitter in order to identify tweets reporting a combination of symptoms consistent with a case definition of ARC and those reporting the name of an antihistamine drug. In order to increase the sensitivity of the system, we applied an algorithm aimed at automatically identifying jargon expressions related to medical terms. We compared weekly Twitter trends with National Allergy Bureau weekly pollen counts derived from US stations, and found a high correlation of the sum of the total pollen counts from each stations with tweets reporting ARC symptoms (Pearson's correlation coefficient: 0.95) and with tweets reporting antihistamine drug names (Pearson's correlation coefficient: 0.93). Longitude and latitude of the pollen stations affected the strength of the correlation. Twitter and other social networks may play a role in allergic disease surveillance and in signaling drug consumptions trends.
Gesualdo, Francesco; Stilo, Giovanni; D'Ambrosio, Angelo; Carloni, Emanuela; Pandolfi, Elisabetta; Velardi, Paola; Fiocchi, Alessandro; Tozzi, Alberto E
2015-01-01
Pollen forecasts are in use everywhere to inform therapeutic decisions for patients with allergic rhinoconjunctivitis (ARC). We exploited data derived from Twitter in order to identify tweets reporting a combination of symptoms consistent with a case definition of ARC and those reporting the name of an antihistamine drug. In order to increase the sensitivity of the system, we applied an algorithm aimed at automatically identifying jargon expressions related to medical terms. We compared weekly Twitter trends with National Allergy Bureau weekly pollen counts derived from US stations, and found a high correlation of the sum of the total pollen counts from each stations with tweets reporting ARC symptoms (Pearson's correlation coefficient: 0.95) and with tweets reporting antihistamine drug names (Pearson's correlation coefficient: 0.93). Longitude and latitude of the pollen stations affected the strength of the correlation. Twitter and other social networks may play a role in allergic disease surveillance and in signaling drug consumptions trends. PMID:26197474
Correlations between blood glucose and breath components from portable gas sensors and PTR-TOF-MS.
Righettoni, M; Schmid, A; Amann, A; Pratsinis, S E
2013-09-01
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
Quantum Correlations from the Conditional Statistics of Incomplete Data.
Sperling, J; Bartley, T J; Donati, G; Barbieri, M; Jin, X-M; Datta, A; Vogel, W; Walmsley, I A
2016-08-19
We study, in theory and experiment, the quantum properties of correlated light fields measured with click-counting detectors providing incomplete information on the photon statistics. We establish a correlation parameter for the conditional statistics, and we derive the corresponding nonclassicality criteria for detecting conditional quantum correlations. Classical bounds for Pearson's correlation parameter are formulated that allow us, once they are violated, to determine nonclassical correlations via the joint statistics. On the one hand, we demonstrate nonclassical correlations in terms of the joint click statistics of light produced by a parametric down-conversion source. On the other hand, we verify quantum correlations of a heralded, split single-photon state via the conditional click statistics together with a generalization to higher-order moments. We discuss the performance of the presented nonclassicality criteria to successfully discern joint and conditional quantum correlations. Remarkably, our results are obtained without making any assumptions on the response function, quantum efficiency, and dark-count rate of photodetectors. PMID:27588857
Quantum Correlations from the Conditional Statistics of Incomplete Data
NASA Astrophysics Data System (ADS)
Sperling, J.; Bartley, T. J.; Donati, G.; Barbieri, M.; Jin, X.-M.; Datta, A.; Vogel, W.; Walmsley, I. A.
2016-08-01
We study, in theory and experiment, the quantum properties of correlated light fields measured with click-counting detectors providing incomplete information on the photon statistics. We establish a correlation parameter for the conditional statistics, and we derive the corresponding nonclassicality criteria for detecting conditional quantum correlations. Classical bounds for Pearson's correlation parameter are formulated that allow us, once they are violated, to determine nonclassical correlations via the joint statistics. On the one hand, we demonstrate nonclassical correlations in terms of the joint click statistics of light produced by a parametric down-conversion source. On the other hand, we verify quantum correlations of a heralded, split single-photon state via the conditional click statistics together with a generalization to higher-order moments. We discuss the performance of the presented nonclassicality criteria to successfully discern joint and conditional quantum correlations. Remarkably, our results are obtained without making any assumptions on the response function, quantum efficiency, and dark-count rate of photodetectors.
Quantum Correlations from the Conditional Statistics of Incomplete Data.
Sperling, J; Bartley, T J; Donati, G; Barbieri, M; Jin, X-M; Datta, A; Vogel, W; Walmsley, I A
2016-08-19
We study, in theory and experiment, the quantum properties of correlated light fields measured with click-counting detectors providing incomplete information on the photon statistics. We establish a correlation parameter for the conditional statistics, and we derive the corresponding nonclassicality criteria for detecting conditional quantum correlations. Classical bounds for Pearson's correlation parameter are formulated that allow us, once they are violated, to determine nonclassical correlations via the joint statistics. On the one hand, we demonstrate nonclassical correlations in terms of the joint click statistics of light produced by a parametric down-conversion source. On the other hand, we verify quantum correlations of a heralded, split single-photon state via the conditional click statistics together with a generalization to higher-order moments. We discuss the performance of the presented nonclassicality criteria to successfully discern joint and conditional quantum correlations. Remarkably, our results are obtained without making any assumptions on the response function, quantum efficiency, and dark-count rate of photodetectors.
On correlated reaction sets and coupled reaction sets in metabolic networks.
Marashi, Sayed-Amir; Hosseini, Zhaleh
2015-08-01
Two reactions are in the same "correlated reaction set" (or "Co-Set") if their fluxes are linearly correlated. On the other hand, two reactions are "coupled" if nonzero flux through one reaction implies nonzero flux through the other reaction. Flux correlation analysis has been previously used in the analysis of enzyme dysregulation and enzymopathy, while flux coupling analysis has been used to predict co-expression of genes and to model network evolution. The goal of this paper is to emphasize, through a few examples, that these two concepts are inherently different. In other words, except for the case of full coupling, which implies perfect correlation between two fluxes (R(2) = 1), there are no constraints on Pearson correlation coefficients (CC) in case of any other type of (un)coupling relations. In other words, Pearson CC can take any value between 0 and 1 in other cases. Furthermore, by analyzing genome-scale metabolic networks, we confirm that there are some examples in real networks of bacteria, yeast and human, which approve that flux coupling and flux correlation cannot be used interchangeably.
Explore Interregional EEG Correlations Changed by Sport Training Using Feature Selection
2016-01-01
This paper investigated the interregional correlation changed by sport training through electroencephalography (EEG) signals using the techniques of classification and feature selection. The EEG data are obtained from students with long-time professional sport training and normal students without sport training as baseline. Every channel of the 19-channel EEG signals is considered as a node in the brain network and Pearson Correlation Coefficients are calculated between every two nodes as the new features of EEG signals. Then, the Partial Least Square (PLS) is used to select the top 10 most varied features and Pearson Correlation Coefficients of selected features are compared to show the difference of two groups. Result shows that the classification accuracy of two groups is improved from 88.13% by the method using measurement of EEG overall energy to 97.19% by the method using EEG correlation measurement. Furthermore, the features selected reveal that the most important interregional EEG correlation changed by training is the correlation between left inferior frontal and left middle temporal with a decreased value. PMID:26880880
Esquivel, G B; Lopez, E
1988-10-01
This study explored the correlations among nonverbal reasoning ability, creativity, and academic achievement in gifted minority children, 89 girls and 71 boys in Grades 1 through 8 in a program for gifted. A random half of students from all grade levels were tested at the beginning of the year and the remaining half after 7 mo. with Raven Progressive Matrices, Torrance Tests of Creative Thinking, and the California Achievement Test. Pearson correlations reflected limited relations among these variables except for a significant positive value between creativity and reading achievement. Suggestions for further study and implications for identification procedures and program development were provided.
Musculoskeletal symptoms, postural disorders and occupational risk factors: correlation analysis.
Comper, Maria Luiza C; Macedo, Felipe; Padula, Rosimeire S
2012-01-01
Work-related musculoskeletal disorders (WRMSD) include a list of inflammatory and degenerative diseases characterized by the presence of musculoskeletal symptoms, compensatory posture changes and functional disabilities. The objective of this study was to evaluate the kinetic/functional characteristics of textile plant workers, their level of exposure to risk factors and the contribution these make to musculoskeletal symptoms. The sample of 42 workers answered the Nordic Questionnaire and the Job Factors Questionnaire. The kinetic/functional characteristics of each worker were verified by a blinded evaluator. Data were analyzed using descriptive statistics and Pearson's correlation. Musculoskeletal symptoms were more prevalent in the spinal region and upper limbs. The exposure levels to risk factors were identified as a serious problem. Postural disorders, musculoskeletal symptoms and risk factors were correlated (P ≤ 0.05).
Correlates of sophisticated listener judgments of esophageal air intake noise.
Knox, A W; Eccleston, V; Maurer, J F; Gordon, M C
1987-02-01
Twenty-four laryngectomies, ranging widely in speaking ability, read a standard passage for audio recording. Four experienced voice clinicians rated the acceptability of the speakers' air intake noise. Independently, overall speech proficiency ratings were obtained for 18 of the subjects. Five objective measures of the subjects' esophageal speech were obtained using a real-time intensity display on a storage oscilloscope. Judges' reliability was determined by Pearson Product Moment Correlations. Ratings were submitted to multiple regression analysis. The means of air intake noise acceptability were the criterion variables; the objective measures and speech proficiency scores were the predictor variables. Three predictors were positively correlated (less than .01) with air intake acceptability: the number of syllables per intake, the sound intensity of the intake, and the rate of speech. Syllables per intake provided the largest share of the variance.
Does APO ε4 correlate with MRI changes in Alzheimer's disease?
Doody, R; Azher, S; Haykal, H; Dunn, J; Liao, T; Schneider, L
2000-01-01
OBJECTIVE—To assess the relation between APO E genotype and MRI white matter changes in Alzheimer's disease. The APO ε4 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 χ2 for demographic and disease related variables. RESULTS—30 patients had no ε4, 53 patients were heterozygous, and 21 patients were homozygous. The three groups did not differ in sex distribution, age of onset, age at MRI, MMSE, clinical dementia rating, or modified Hachinski ischaemia scores. There were no significant correlations between total or regional white matter scores and APO E genotype (Pearson correlation). CONCLUSIONS—No correlation between total or regional white matter scores and APO E genotype was found. The pathogenesis of white matter changes in Alzheimer's disease may be independent of APO E genotype. PMID:11032626
Closure and ratio correlation analysis of lunar chemical and grain size data
NASA Technical Reports Server (NTRS)
Butler, J. C.
1976-01-01
Major element and major element plus trace element analyses were selected from the lunar data base for Apollo 11, 12 and 15 basalt and regolith samples. Summary statistics for each of the six data sets were compiled, and the effects of closure on the Pearson product moment correlation coefficient were investigated using the Chayes and Kruskal approximation procedure. In general, there are two types of closure effects evident in these data sets: negative correlations of intermediate size which are solely the result of closure, and correlations of small absolute value which depart significantly from their expected closure correlations which are of intermediate size. It is shown that a positive closure correlation will arise only when the product of the coefficients of variation is very small (less than 0.01 for most data sets) and, in general, trace elements in the lunar data sets exhibit relatively large coefficients of variation.
Inferring correlation networks from genomic survey data.
Friedman, Jonathan; Alm, Eric J
2012-01-01
High-throughput sequencing based techniques, such as 16S rRNA gene profiling, have the potential to elucidate the complex inner workings of natural microbial communities - be they from the world's oceans or the human gut. A key step in exploring such data is the identification of dependencies between members of these communities, which is commonly achieved by correlation analysis. However, it has been known since the days of Karl Pearson that the analysis of the type of data generated by such techniques (referred to as compositional data) can produce unreliable results since the observed data take the form of relative fractions of genes or species, rather than their absolute abundances. Using simulated and real data from the Human Microbiome Project, we show that such compositional effects can be widespread and severe: in some real data sets many of the correlations among taxa can be artifactual, and true correlations may even appear with opposite sign. Additionally, we show that community diversity is the key factor that modulates the acuteness of such compositional effects, and develop a new approach, called SparCC (available at https://bitbucket.org/yonatanf/sparcc), which is capable of estimating correlation values from compositional data. To illustrate a potential application of SparCC, we infer a rich ecological network connecting hundreds of interacting species across 18 sites on the human body. Using the SparCC network as a reference, we estimated that the standard approach yields 3 spurious species-species interactions for each true interaction and misses 60% of the true interactions in the human microbiome data, and, as predicted, most of the erroneous links are found in the samples with the lowest diversity. PMID:23028285
Inferring Correlation Networks from Genomic Survey Data
Friedman, Jonathan; Alm, Eric J.
2012-01-01
High-throughput sequencing based techniques, such as 16S rRNA gene profiling, have the potential to elucidate the complex inner workings of natural microbial communities - be they from the world's oceans or the human gut. A key step in exploring such data is the identification of dependencies between members of these communities, which is commonly achieved by correlation analysis. However, it has been known since the days of Karl Pearson that the analysis of the type of data generated by such techniques (referred to as compositional data) can produce unreliable results since the observed data take the form of relative fractions of genes or species, rather than their absolute abundances. Using simulated and real data from the Human Microbiome Project, we show that such compositional effects can be widespread and severe: in some real data sets many of the correlations among taxa can be artifactual, and true correlations may even appear with opposite sign. Additionally, we show that community diversity is the key factor that modulates the acuteness of such compositional effects, and develop a new approach, called SparCC (available at https://bitbucket.org/yonatanf/sparcc), which is capable of estimating correlation values from compositional data. To illustrate a potential application of SparCC, we infer a rich ecological network connecting hundreds of interacting species across 18 sites on the human body. Using the SparCC network as a reference, we estimated that the standard approach yields 3 spurious species-species interactions for each true interaction and misses 60% of the true interactions in the human microbiome data, and, as predicted, most of the erroneous links are found in the samples with the lowest diversity. PMID:23028285
Sella size and jaw bases - Is there a correlation???
Neha; Mogra, Subraya; Shetty, Vorvady Surendra; Shetty, Siddarth
2016-01-01
Introduction: Sella turcica is an important cephalometric structure and attempts have been made in the past to correlate its dimensions to the malocclusion. However, no study has so far compared the size of sella to the jaw bases that determine the type of malocclusion. The present study was undertaken to find out any such correlation if it exists. Materials and Methods: Lateral cephalograms of 110 adults consisting of 40 Class I, 40 Class II, and 30 Class III patients were assessed for the measurement of sella length, width, height, and area. The maxillary length, mandibular ramus height, and body length were also measured. The sella dimensions were compared among three malocclusion types by one-way ANOVA. Pearson correlation was calculated between the jaw size and sella dimensions. Furthermore, the ratio of jaw base lengths and sella area were calculated. Results and Conclusion: Mean sella length, width and area were found to be greatest in Class III, followed by Class I and least in Class II though the results were not statistically significant. 3 out of 4 measured dimensions of sella, correlated significantly with mandibular ramus and body length each. However, only one dimension of sella showed significant correlation with maxilla. The mandibular ramus and body length show a nearly constant ratio to sella area (0.83–0.85, 0.64–0.65, respectively) in all the three malocclusions. Thus, mandible has a definite and better correlation to the size of sella turcica. PMID:27041903
Robust asymptotic sampling theory for correlations in pedigrees.
Keen, K J; Elston, Robert C
2003-10-30
Methods to unravel the genetic determinants of non-Mendelian diseases lie at the next frontier of statistical approaches for human genetics. It is generally agreed that, before proceeding with segregation or linkage analysis, the trait under study ought to be shown to exhibit familial correlation. By coding dichotomous traits as binary variables, a single robust approach in the estimation of pedigree correlations, rather than two distinct approaches, can be used to assess the potential heritability of a trait, and, latterly, to examine the mode of inheritance. The asymptotic theory to conduct hypothesis tests and confidence intervals for correlations among different members of nuclear families is well established but is applicable only if the nuclear families are independent. As a further contribution to the literature, we derive the asymptotic sampling distribution of correlations between random variables among arbitrary pairs of members in extended families for the Pearson product-moment estimator with generalized weights. This derivation is done without assuming normality of the traits. The sampling distribution is shown to be asymptotically normal to first order, and hence large-sample hypothesis tests and confidence intervals with estimates of the variances and correlation coefficients are proposed. Discussion concludes with an example and a suggestion for future research.
Seasonal Distribution and Climatic Correlates of Dengue Disease in Dhaka, Bangladesh.
Morales, Ivonne; Salje, Henrik; Saha, Samir; Gurley, Emily S
2016-06-01
Dengue has been regularly reported in Dhaka, Bangladesh, since a large outbreak in 2000. However, to date, we have limited information on the seasonal distribution of dengue disease and how case distribution correlates with climate. Here, we analyzed dengue cases detected at a private diagnostic facility in Dhaka during 2010-2014. We calculated Pearson cross-correlation coefficients to examine the relationship between the timing of cases and both rainfall and temperature. There were 2,334 cases diagnosed during the study period with 76% over the age of 15 years. Cases were reported in every month of the study; however, 90% of cases occurred between June and November. Increases in rainfall were correlated with increases in cases 2 months later (correlation of 0.7). The large proportion of adult cases is consistent with substantial population susceptibility and suggests Dhaka remains at risk for outbreaks. Although cases occurred year-round, public health preparedness should be focused during peak months.
NASA Astrophysics Data System (ADS)
Sun, Xuelian; Liu, Zixian
2016-02-01
In this paper, a new estimator of correlation matrix is proposed, which is composed of the detrended cross-correlation coefficients (DCCA coefficients), to improve portfolio optimization. In contrast to Pearson's correlation coefficients (PCC), DCCA coefficients acquired by the detrended cross-correlation analysis (DCCA) method can describe the nonlinear correlation between assets, and can be decomposed in different time scales. These properties of DCCA make it possible to improve the investment effect and more valuable to investigate the scale behaviors of portfolios. The minimum variance portfolio (MVP) model and the Mean-Variance (MV) model are used to evaluate the effectiveness of this improvement. Stability analysis shows the effect of two kinds of correlation matrices on the estimation error of portfolio weights. The observed scale behaviors are significant to risk management and could be used to optimize the portfolio selection.
ERIC Educational Resources Information Center
White, Amanda Garrett
2009-01-01
The purpose of the mix-methods action research study was to seek how the changes in students' perceptions about teacher classroom interpersonal behaviors, the four efficacy sources and mathematics self-efficacy beliefs were related. The methods used to accomplish this were: descriptive statistics, t-test, Pearson correlation coefficient…
ERIC Educational Resources Information Center
Shelley, Mack C., II; Schuh, John H.
This study examined the relationship between writing quality, readability, and selectivity in 17 higher education journals. Readability was assessed through two indexes of readability. Data were analyzed using zero-order Pearson product-moment correlations, independent two sample t-tests, and analysis of covariance. Findings show that quality of…
ERIC Educational Resources Information Center
Dev, Smitha; Qiqieh, Sura
2016-01-01
The present study aims to find out the relationship between English Language proficiency, self-esteem, and academic achievement of the students in Abu Dhabi University (ADU). The variables were analyzed using "t" test, chi-squire and Pearson's product moment correlation. In addition, Self-rating scale, Self-esteem inventory and Language…
Substance Abuse Counselors and Moral Reasoning: Hypothetical and Authentic Dilemmas
ERIC Educational Resources Information Center
Sias, Shari M.
2009-01-01
This exploratory study examined the assumption that the level of moral reasoning (Defining Issues Test; J. R. Rest, 1986) used in solving hypothetical and authentic dilemmas is similar for substance abuse counselors (N = 188). The statistical analyses used were paired-sample t tests, Pearson product-moment correlation, and simultaneous multiple…
Correlation in instruments - Cross correlation flowmeters
NASA Astrophysics Data System (ADS)
Beck, M. S.
1981-01-01
The principles of cross-correlation flowmeters are presented demonstrating methods of identifying dynamic properties of telecommunication, structural, and process systems. The flowmeters are designed for measurements of the transit time of a tagging signal such as turbulence or clumps of particles in the flow between two axially separated sensors; the transit time is measured by a cross-correlator. Cross-correlation flowmeters can reduce large scale integrated circuit costs and will be applied to environmental and industrial measurement problems.
Correlation between gene expression and GO semantic similarity.
Sevilla, José L; Segura, Víctor; Podhorski, Adam; Guruceaga, Elizabeth; Mato, José M; Martínez-Cruz, Luis A; Corrales, Fernando J; Rubio, Angel
2005-01-01
This research analyzes some aspects of the relationship between gene expression, gene function, and gene annotation. Many recent studies are implicitly based on the assumption that gene products that are biologically and functionally related would maintain this similarity both in their expression profiles as well as in their Gene Ontology (GO) annotation. We analyze how accurate this assumption proves to be using real publicly available data. We also aim to validate a measure of semantic similarity for GO annotation. We use the Pearson correlation coefficient and its absolute value as a measure of similarity between expression profiles of gene products. We explore a number of semantic similarity measures (Resnik, Jiang, and Lin) and compute the similarity between gene products annotated using the GO. Finally, we compute correlation coefficients to compare gene expression similarity against GO semantic similarity. Our results suggest that the Resnik similarity measure outperforms the others and seems better suited for use in Gene Ontology. We also deduce that there seems to be correlation between semantic similarity in the GO annotation and gene expression for the three GO ontologies. We show that this correlation is negligible up to a certain semantic similarity value; then, for higher similarity values, the relationship trend becomes almost linear. These results can be used to augment the knowledge provided by clustering algorithms and in the development of bioinformatic tools for finding and characterizing gene products.
Wu, Yong; Eghbali, Mansoureh; Ou, Jimmy; Lu, Rong; Toro, Ligia; Stefani, Enrico
2010-01-01
Abstract To quantify spatial protein-protein proximity (colocalization) in paired microscopic images of two sets of proteins labeled by distinct fluorophores, we showed that the cross-correlation and the autocorrelation functions of image intensity consisted of fast and slowly decaying components. The fast component resulted from clusters of proteins specifically labeled, and the slow component resulted from image heterogeneity and a broadly-distributed background. To better evaluate spatial proximity between the two specifically labeled proteins, we extracted the fast-decaying component by fitting the sharp peak in correlation functions to a Gaussian function, which was then used to obtain protein-protein proximity index and the Pearson's correlation coefficient. We also employed the median-filter method as a universal approach for background reduction to minimize nonspecific fluorescence. We illustrated our method by analyzing computer-simulated images and biological images. PMID:20141764
Li, Johnson Ching-Hong; Chan, Wai; Cui, Ying
2011-11-01
The standard Pearson correlation coefficient, r, is a biased estimator of the population correlation coefficient, ρ(XY) , when predictor X and criterion Y are indirectly range-restricted by a third variable Z (or S). Two correction algorithms, Thorndike's (1949) Case III, and Schmidt, Oh, and Le's (2006) Case IV, have been proposed to correct for the bias. However, to our knowledge, the two algorithms did not provide a procedure to estimate the associated standard error and confidence intervals. This paper suggests using the bootstrap procedure as an alternative. Two Monte Carlo simulations were conducted to systematically evaluate the empirical performance of the proposed bootstrap procedure. The results indicated that the bootstrap standard error and confidence intervals were generally accurate across simulation conditions (e.g., selection ratio, sample size). The proposed bootstrap procedure can provide a useful alternative for the estimation of the standard error and confidence intervals for the correlation corrected for indirect range restriction.
Lass, N J
1978-04-01
The purpose of this investigation was to determine the relationship among speakers' heights, weights, body surface areas, and speaking fundamental frequencies. The recordings of 30 speakers' readings of a standard prose passage were analyzed by means of the Fundamental Frequency Indicator (FFI) to obtain their speaking fundamental frequency characteristics. The speakers' heights and weights were obtained by means of standard measurement procuedures, and their body surface areas were calculated. Pearson product-moment correlation coefficients, computed separately for men and women, indicated that speakers' heights, weights, and body surface areas were not significantly correlated with their speaking fundamental frequencies; female speakers showed a slight negative correlation while male speakers showed a low, positive trend. Implications of these findings and suggestions for future research are discussed.
Fitch, Alistair J; Kadyrov, Alexander; Christmas, William J; Kittler, Josef
2005-08-01
A new, fast, statistically robust, exhaustive, translational image-matching technique is presented: fast robust correlation. 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 to be fast. Speed is comparable to conventional correlation and, for large images, thousands of times faster than direct robust matching. Three experiments demonstrate the advantage of the technique over standard correlation.
Correlation between nasal membrane permeability and nasal absorption rate.
Zhang, Hefei; Lin, Chih-Wei; Donovan, Maureen D
2013-03-01
The objective of this study was to investigate the relationship between in vitro permeability (Papp) values obtained from isolated nasal tissues and the absorption rates (ka) of the same compounds following nasal administration in animals and humans. The Papp of a set of 11 drug compounds was measured using animal nasal explants and plasma time-concentration profiles for each of the same compounds following intravenous (IV) and intranasal (IN) administration were experimentally determined or obtained from literature reports. The plasma clearance was estimated from the IV plasma time-concentration profiles, and ka was determined from the IN plasma time-concentration profiles using a deconvolution approach. The level of correlation between Papp and ka was established using Pearson correlation analysis. A good correlation (r=0.77) representing a point-to-point relationship for each of the compounds was observed. This result indicates that the nasal absorption for many drug candidates can be estimated from a readily measured in vitro Papp value. PMID:23225081
Correlative study of 3 pain rating scales among obstetric patients.
Akinpelu, A O; Olowe, O O
2002-06-01
The relationship between pain scores obtained on the Visual Analog Scale (VAS) the Box Numerical Scale (BNS) and Verbal Rating Scale (VRS) was studied. The subjects were 35 volunteer female patients who had their babies through caesarian section 1-3 days prior to the study. Demographic data and pain scores were collected through a questionnaire, which was available in both English and Yoruba, the two most commonly spoken languages in Ibadan where the study was carried out. Data were analysed using Pearson Product, Moment Correlation Coefficient, and One-way Analysis of Variance. Results indicated that there was no significant difference between the pain scores obtained on the 3 pain rating scales. Significant correlations existed between pain scores obtained on the VAS and VRS (r = 0.48, p = 0.003); VAS and BNS (r = 0.74, P = 0.000); BNS and VRS (r = 0.74, P = 0.000). High educational attainment improved correlation between the scales in this study. It was concluded that the three pain rating scales measure the same construct, and could be used for pain measurement in obstetrically related conditions in this environment.
Knudsen, Anders R; Andersen, Kasper J; Hamilton-Dutoit, Stephen; Nyengaard, Jens R; Mortensen, Frank V
2016-04-01
Circulating liver enzymes such as alanine transaminase are often used as markers of hepatocellular damage. Ischaemia/reperfusion (I/R) injury is an inevitable consequence of prolonged liver ischaemia. The aim of this study was to examine the correlation between liver enzymes and volume of liver cell necrosis after ischaemia/reperfusion injuries, using design-unbiased stereological methods. Forty-seven male Wistar rats were subjected to 1 h of partial liver ischaemia, followed by either 4 or 24 h of reperfusion. Within each group, one-third of animals were subjected to ischaemic preconditioning and one-third to ischaemic postconditioning. At the end of reperfusion, blood and liver samples were collected for analysis. The volume of necrotic liver tissue was subsequently correlated to circulating markers of I/R injury. Correlation between histological findings and circulating markers was performed using Pearson's correlation coefficient. Alanine transferase peaked after 4 h of reperfusion; however, at this time-point, only mild necrosis was observed, with a Pearson's correlation coefficient of 0.663 (P = 0.001). After 24 h of reperfusion, alanine aminotransferase was found to be highly correlated to the degree of hepatocellular necrosis R = 0.836 (P = 0.000). Furthermore, alkaline phosphatase (R = 0.806) and α-2-macroglobulin (R = 0.655) levels were also correlated with the degree of necrosis. We show for the first time that there is a close correlation between the volume of hepatocellular necrosis and alanine aminotransferase levels in a model of I/R injury. This is especially apparent after 24 h of reperfusion. Similarly, increased levels of alkaline phosphatase and α-2-macroglobulin are correlated to the volume of liver necrosis. PMID:27292534
NASA Technical Reports Server (NTRS)
Surkis, Igor; Ken, Voitsekh; Melnikov, Alexey; Mishin, Vladimir; Sokolova, Nadezda; Shantyr, Violet; Zimovsky, Vladimir
2013-01-01
The activities of the six-station IAA RAS correlator include regular processing of national geodetic VLBI programs Ru-E, Ru-U, and Ru-F. The Ru-U sessions have been transferred in e-VLBI mode and correlated in the IAA Correlator Center automatically since 2011. The DiFX software correlator is used at the IAA in some astrophysical experiments.
ERIC Educational Resources Information Center
Kozak, Marcin
2009-01-01
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…
Optical correlator tracking nonlinearity
NASA Astrophysics Data System (ADS)
Gregory, Don A.; Kirsch, James C.; Johnson, John L.
1987-01-01
A limitation observed in the tracking ability of optical correlators is reported. It is shown by calculations that an inherent nonlinearity exists in many optical correlator configurations, with the problem manifesting itself in a mismatch of the input scene with the position of the correlation signal. Results indicate that some care must be given to the selection of components and their configuration in constructing an optical correlator which exhibits true translational invariance. An input test scene is shown along with the correlation spot and cross hairs from a contrast detector; the offset is apparent.
NASA Astrophysics Data System (ADS)
Luo, Shun-Long; Li, Nan
2008-02-01
Werner states are paradigmatic examples of quantum states and play an innovative role in quantum information theory. In investigating the correlating capability of Werner states, we find the curious phenomenon that quantum correlations, as quantified by the entanglement of formation, may exceed the total correlations, as measured by the quantum mutual information. Consequently, though the entanglement of formation is so widely used in quantifying entanglement, it cannot be interpreted as a consistent measure of quantum correlations per se if we accept the folklore that total correlations are measured (or rather upper bounded) by the quantum mutual information.
NASA Astrophysics Data System (ADS)
Nelson, D. J.
2007-09-01
In the basic correlation process a sequence of time-lag-indexed correlation coefficients are computed as the inner or dot product of segments of two signals. The time-lag(s) for which the magnitude of the correlation coefficient sequence is maximized is the estimated relative time delay of the two signals. For discrete sampled signals, the delay estimated in this manner is quantized with the same relative accuracy as the clock used in sampling the signals. In addition, the correlation coefficients are real if the input signals are real. There have been many methods proposed to estimate signal delay to more accuracy than the sample interval of the digitizer clock, with some success. These methods include interpolation of the correlation coefficients, estimation of the signal delay from the group delay function, and beam forming techniques, such as the MUSIC algorithm. For spectral estimation, techniques based on phase differentiation have been popular, but these techniques have apparently not been applied to the correlation problem . We propose a phase based delay estimation method (PBDEM) based on the phase of the correlation function that provides a significant improvement of the accuracy of time delay estimation. In the process, the standard correlation function is first calculated. A time lag error function is then calculated from the correlation phase and is used to interpolate the correlation function. The signal delay is shown to be accurately estimated as the zero crossing of the correlation phase near the index of the peak correlation magnitude. This process is nearly as fast as the conventional correlation function on which it is based. For real valued signals, a simple modification is provided, which results in the same correlation accuracy as is obtained for complex valued signals.
Degree correlations in directed scale-free networks.
Williams, Oliver; Del Genio, Charo I
2014-01-01
Scale-free networks, in which the distribution of the degrees obeys a power-law, are ubiquitous in the study of complex systems. One basic network property that relates to the structure of the links found is the degree assortativity, which is a measure of the correlation between the degrees of the nodes at the end of the links. Degree correlations are known to affect both the structure of a network and the dynamics of the processes supported thereon, including the resilience to damage, the spread of information and epidemics, and the efficiency of defence mechanisms. Nonetheless, while many studies focus on undirected scale-free networks, the interactions in real-world systems often have a directionality. Here, we investigate the dependence of the degree correlations on the power-law exponents in directed scale-free networks. To perform our study, we consider the problem of building directed networks with a prescribed degree distribution, providing a method for proper generation of power-law-distributed directed degree sequences. Applying this new method, we perform extensive numerical simulations, generating ensembles of directed scale-free networks with exponents between 2 and 3, and measuring ensemble averages of the Pearson correlation coefficients. Our results show that scale-free networks are on average uncorrelated across directed links for three of the four possible degree-degree correlations, namely in-degree to in-degree, in-degree to out-degree, and out-degree to out-degree. However, they exhibit anticorrelation between the number of outgoing connections and the number of incoming ones. The findings are consistent with an entropic origin for the observed disassortativity in biological and technological networks.
Gesell, Sabina B; Clark, Paul Alexander; Mylod, Deirdre E; Wolosin, Robert J; Drain, Maxwell; Lanser, Peter; Hall, Melvin F
2005-01-01
A national cross-sectional study correlates the satisfaction ratings of heart failure patients (diagnosis related group 127) and the Centers for Medicare & Medicaid Services' process-based quality measures for heart failure treatment for 32 hospitals during the first and second quarters of 2004. Two of the four measures of clinical quality showed statistically significant, moderately strong, positive correlations with a global measure of satisfaction and with, respectively, 5 and 7 subscales of the 10 subscales of satisfaction under examination (Pearson's r ranged between .40 and .67, 2-tailed; p < .05). Findings demonstrate that quality need not be a zero-sum issue, with clinical quality and service quality competing for resources and attention.
Investigation of the correlation between the different mechanical properties of resin composites.
Jun, Soo-Kyung; Kim, Dong-Ae; Goo, Hyo-Jin; Lee, Hae-Hyoung
2013-01-01
The aim of this study was to investigate the relationship between the different mechanical properties with the filler fraction of various resin composites. Mechanical properties of eighteen different resin composites were investigated in this study; flexural strength (FS), flexural modulus (FM), fracture toughness (FT), compressive strength (CS), diametral tensile strength (DTS), Barcol hardness (BH), Vickers hardness (HV), and Knoop hardness (HK). The mean values of mechanical properties and the filler fractions (V(f )) obtained from the literature and the manufacturer were analyzed using Pearson's correlation test at p<0.01. The relationships were compared with the data retrieved from previous studies. Strong correlations between Vf and BH/HV/HK and V(f) and FM were evident in the results of the present study and these results were supported by the retrieved data from previous studies. The other relationships between mechanical properties, such as that between FS and FM and between CS and HV were not significant. PMID:23370870
Correlation and agreement: overview and clarification of competing concepts and measures.
Liu, Jinyuan; Tang, Wan; Chen, Guanqin; Lu, Yin; Feng, Changyong; Tu, Xin M
2016-04-25
Agreement and correlation are widely-used concepts that assess the association between variables. Although similar and related, they represent completely different notions of association. Assessing agreement between variables assumes that the variables measure the same construct, while correlation of variables can be assessed for variables that measure completely different constructs. This conceptual difference requires the use of different statistical methods, and when assessing agreement or correlation, the statistical method may vary depending on the distribution of the data and the interest of the investigator. For example, the Pearson correlation, a popular measure of correlation between continuous variables, is only informative when applied to variables that have linear relationships; it may be non-informative or even misleading when applied to variables that are not linearly related. Likewise, the intraclass correlation, a popular measure of agreement between continuous variables, may not provide sufficient information for investigators if the nature of poor agreement is of interest. This report reviews the concepts of agreement and correlation and discusses differences in the application of several commonly used measures. PMID:27605869
Correlation and agreement: overview and clarification of competing concepts and measures
LIU, Jinyuan; TANG, Wan; CHEN, Guanqin; LU, Yin; FENG, Changyong; TU, Xin M.
2016-01-01
Summary: Agreement and correlation are widely-used concepts that assess the association between variables. Although similar and related, they represent completely different notions of association. Assessing agreement between variables assumes that the variables measure the same construct, while correlation of variables can be assessed for variables that measure completely different constructs. This conceptual difference requires the use of different statistical methods, and when assessing agreement or correlation, the statistical method may vary depending on the distribution of the data and the interest of the investigator. For example, the Pearson correlation, a popular measure of correlation between continuous variables, is only informative when applied to variables that have linear relationships; it may be non-informative or even misleading when applied to variables that are not linearly related. Likewise, the intraclass correlation, a popular measure of agreement between continuous variables, may not provide sufficient information for investigators if the nature of poor agreement is of interest. This report reviews the concepts of agreement and correlation and discusses differences in the application of several commonly used measures.
Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.
2016-01-01
Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123
Statistical functions and relevant correlation coefficients of clearness index
NASA Astrophysics Data System (ADS)
Pavanello, Diego; Zaaiman, Willem; Colli, Alessandra; Heiser, John; Smith, Scott
2015-08-01
This article presents a statistical analysis of the sky conditions, during years from 2010 to 2012, for three different locations: the Joint Research Centre site in Ispra (Italy, European Solar Test Installation - ESTI laboratories), the site of National Renewable Energy Laboratory in Golden (Colorado, USA) and the site of Brookhaven National Laboratories in Upton (New York, USA). The key parameter is the clearness index kT, a dimensionless expression of the global irradiance impinging upon a horizontal surface at a given instant of time. In the first part, the sky conditions are characterized using daily averages, giving a general overview of the three sites. In the second part the analysis is performed using data sets with a short-term resolution of 1 sample per minute, demonstrating remarkable properties of the statistical distributions of the clearness index, reinforced by a proof using fuzzy logic methods. Successively some time-dependent correlations between different meteorological variables are presented in terms of Pearson and Spearman correlation coefficients, and introducing a new one.
RHIC DATA CORRELATION METHODOLOGY.
MICHNOFF,R.; D'OTTAVIO,T.; HOFF,L.; MACKAY,W.; SATOGATA,T.
1999-03-29
A requirement for RHIC data plotting software and physics analysis is the correlation of data from all accelerator data gathering systems. Data correlation provides the capability for a user to request a plot of multiple data channels vs. time, and to make meaningful time-correlated data comparisons. The task of data correlation for RHIC requires careful consideration because data acquisition triggers are generated from various asynchronous sources including events from the RHIC Event Link, events from the two Beam Sync Links, and other unrelated clocks. In order to correlate data from asynchronous acquisition systems a common time reference is required. The RHIC data correlation methodology will allow all RHIC data to be converted to a common wall clock time, while still preserving native acquisition trigger information. A data correlation task force team, composed of the authors of this paper, has been formed to develop data correlation design details and provide guidelines for software developers. The overall data correlation methodology will be presented in this paper.
Kim, Mock Ryeon; Park, Hye Won; Son, Jae Sung; Lee, Ran
2016-01-01
Purpose To evaluate the correlation between colon transit time (CTT) test value and initial maintenance dose of polyethylene glycol (PEG) 4000 or lactulose. Methods Of 415 children with chronic functional constipation, 190 were enrolled based on exclusion criteria using the CTT test, defecation diary, and clinical chart. The CTT test was performed with prior disimpaction. The laxative dose for maintenance was determined on the basis of the defecation diary and clinical chart. The Shapiro-Wilk test and Pearson's and Spearman's correlations were used for statistical analysis. Results The overall group median value and interquartile range of the CTT test was 43.8 (31.8) hours. The average PEG 4000 dose for maintenance in the overall group was 0.68±0.18 g/kg/d; according to age, the dose was 0.73±0.16 g/kg/d (<8 years), 0.53±0.12 g/kg/d (8 to <12 years), and 0.36±0.05 g/kg/d (12 to 15 years). The dose of lactulose was 1.99±0.43 mL/kg/d (<8 years) or 1.26±0.25 mL/kg/d (8 to <12 years). There was no significant correlation between CTT test value and initial dose of laxative, irrespective of the subgroup (encopresis, abnormal CTT test subtype) for either laxative. Even in the largest group (overall, n=109, younger than 8 years and on PEG 4000), the correlation was weak (Pearson's correlation coefficient [R]=0.268, p=0.005). Within the abnormal transit group, subgroup (n=73, younger than 8 years and on PEG 4000) correlation was weak (R=0.267, p=0.022). Conclusion CTT test value cannot predict the initial maintenance dose of PEG 4000 or lactulose with linear correlation. PMID:27738600
Wang, J; Zhang, H; Wu, C; Han, J; Guo, Z; Jia, C; Yang, L; Hao, Y; Xu, K; Liu, X; Si, J
2015-01-01
ABSTRACT Background: The aim of this study is to evaluate the correlation of the left ventricular diastolic function and the left ventricular geometry in patients with obstructive sleep apnoea syndrome (OSAS) by echocardiography. Methods: The 181 patients diagnosed with OSAS were divided into the normal geometry group (NG), the concentric remodelling group (CR), the eccentric hypertrophy group (EH) and the concentric hypertrophy group (CH). Pearson correlation analysis and multiple linear regression analysis were performed toward the correlation of the left ventricular diastolic function and the left ventricular geometry. Results: The E peak in the EH and CH group was significantly reduced, with significant difference; the E/A, Em, Am and Em/Am was reduced in the order of the CR, EH and CH groups, while E/Em was increased, and the difference was significant. Pearson correlation analysis revealed that the Em/Am showed significant negative correlations with the left ventricular mass index (LVMI) [r = −0.419] and relative wall thickness (RWT) [r = −0.289], while the E/Em was significantly positively correlated with the LVMI (r = 0.638) and RWT [r = 0.328] (p < 0.001). Multiple linear regression analysis revealed that LVMI and RWT had influence on the Em/Am and E/Em (r2 = 0.402, r2 = 0.107, p < 0.001). The left ventricular diastolic dysfunction was the worst in the CH group. Conclusions: There was correlation between the left ventricular diastolic dysfunction and the changes in cardiac geometry. PMID:26360680
ALMA correlator computer systems
NASA Astrophysics Data System (ADS)
Pisano, Jim; Amestica, Rodrigo; Perez, Jesus
2004-09-01
We present a design for the computer systems which control, configure, and monitor the Atacama Large Millimeter Array (ALMA) correlator and process its output. Two distinct computer systems implement this functionality: a rack- mounted PC controls and monitors the correlator, and a cluster of 17 PCs process the correlator output into raw spectral results. The correlator computer systems interface to other ALMA computers via gigabit Ethernet networks utilizing CORBA and raw socket connections. ALMA Common Software provides the software infrastructure for this distributed computer environment. The control computer interfaces to the correlator via multiple CAN busses and the data processing computer cluster interfaces to the correlator via sixteen dedicated high speed data ports. An independent array-wide hardware timing bus connects to the computer systems and the correlator hardware ensuring synchronous behavior and imposing hard deadlines on the control and data processor computers. An aggregate correlator output of 1 gigabyte per second with 16 millisecond periods and computational data rates of approximately 1 billion floating point operations per second define other hard deadlines for the data processing computer cluster.
Explorations in Statistics: Correlation
ERIC Educational Resources Information Center
Curran-Everett, Douglas
2010-01-01
Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This sixth installment of "Explorations in Statistics" explores correlation, a familiar technique that estimates the magnitude of a straight-line relationship between two variables. Correlation is meaningful only when the…
Ebadifard Azar, Farbod; Sarabi Asiabar, Ali
2015-01-01
Background: Effective leadership is essential to passing through obstacles facing the health field.The current health care system in Iran has major problems and gaps in the field of effective leadership. The aim of this study was to evaluate hospital managers’ leadership style through selfassessment and to determine the correlation between leadership styles with healthcare executives’ leadership readiness and leadership effectiveness. Methods: In this cross-sectional study a self-administered questionnaire completed by all internal healthcare executives of all teaching and non-teaching hospitals affiliated to Iran University of Medical Sciences. Questionnaire was composed to determine demographic information, leadership style questions, leadership effectiveness and leadership readiness. Descriptive statistics and Pearson correlation coefficient were used for data analysis. Results: According to the findings, the dominant style of healthcare executives was transformational leadership style (with a score of 4.34). The leadership effectiveness was estimated at about 4.36 that shows the appropriate level of leadership effectiveness. There was a significant correlation (correlation coefficient of 0.244) between leadership readiness and transformational leadership style (p<0.05). Also, there was a significant correlation between leadership effectiveness with transformational (0.051) and transactional (0.216) styles. Conclusion: There was a correlation between leadership readiness and leadership effectiveness with leadership styles. Application of this research will be crucial to universities and healthcare executives. This study suggests that strengthening the scientific basis is essential for leadership readiness and leadership effectiveness in healthcare system. PMID:26000260
Correlation of Space Shuttle Landing Performance with Post-Flight Cardiovascular Dysfunction
NASA Technical Reports Server (NTRS)
McCluskey, R.
2004-01-01
Introduction: Microgravity induces cardiovascular adaptations resulting in orthostatic intolerance on re-exposure to normal gravity. Orthostasis could interfere with performance of complex tasks during the re-entry phase of Shuttle landings. This study correlated measures of Shuttle landing performance with post-flight indicators of orthostatic intolerance. Methods: Relevant Shuttle landing performance parameters routinely recorded at touchdown by NASA included downrange and crossrange distances, airspeed, and vertical speed. Measures of cardiovascular changes were calculated from operational stand tests performed in the immediate post-flight period on mission commanders from STS-41 to STS-66. Stand test data analyzed included maximum standing heart rate, mean increase in maximum heart rate, minimum standing systolic blood pressure, and mean decrease in standing systolic blood pressure. Pearson correlation coefficients were calculated with the null hypothesis that there was no statistically significant linear correlation between stand test results and Shuttle landing performance. A correlation coefficient? 0.5 with a p<0.05 was considered significant. Results: There were no significant linear correlations between landing performance and measures of post-flight cardiovascular dysfunction. Discussion: There was no evidence that post-flight cardiovascular stand test data correlated with Shuttle landing performance. This implies that variations in landing performance were not due to space flight-induced orthostatic intolerance.
Ruemper, Alia; Watkins, Katherine
2012-12-01
The first objective of this study was to ascertain the prevalence of general joint hypermobility (GJH) and joint hypermobility syndrome (JHS) in BA Dance Theatre 1st and 3rd year students at a contemporary dance conservatory. The second objective was to determine the statistical correlation between GJH, JHS, and injury in this population. A total of 85 (female, N = 78; male, N = 7) contemporary dance students participated in the study. The Beighton score (with a forward flexion test modification) was used to determine GJH, and the Brighton criteria were used to verify JHS. Participants completed a self-reported injury questionnaire that included type of injury (physical complaint, medical diagnosis, or time-loss) and injury frequency. Statistical analysis (Pearson correlation) was used to correlate GJH, JHS, and frequency-of-injury scores. Overall, 69% of the students were found to have GJH, and 33% had JHS. A statistical correlation of r = + 0.331 (p < 0.01) was found between JHS and injury. No significant correlation was found between GJH and injury. This is the first study to look at these correlations in contemporary dance students and suggests that screening programs should include the Brighton criteria to identify JHS in these dancers. Subsequent injury tracking and injury prevention programs would then provide data for further research in this area.
Haystack Observatory VLBI Correlator
NASA Technical Reports Server (NTRS)
Titus, Mike; Cappallo, Roger; Corey, Brian; Dudevoir, Kevin; Niell, Arthur; Whitney, Alan
2013-01-01
This report summarizes the activities of the Haystack Correlator during 2012. Highlights include finding a solution to the DiFX InfiniBand timeout problem and other DiFX software development, conducting a DBE comparison test following the First International VLBI Technology Workshop, conducting a Mark IV and DiFX correlator comparison, more broadband delay experiments, more u- VLBI Galactic Center observations, and conversion of RDV session processing to the Mark IV/HOPS path. Non-real-time e-VLBI transfers and engineering support of other correlators continued.
Correlation Plenoptic Imaging.
D'Angelo, Milena; Pepe, Francesco V; Garuccio, Augusto; Scarcelli, Giuliano
2016-06-01
Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in standard plenoptic imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this Letter, we demonstrate that the correlation in both momentum and position of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging. PMID:27314718
Correlation Plenoptic Imaging.
D'Angelo, Milena; Pepe, Francesco V; Garuccio, Augusto; Scarcelli, Giuliano
2016-06-01
Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in standard plenoptic imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this Letter, we demonstrate that the correlation in both momentum and position of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging.
Nosrati, R; Owlia, P; Saderi, H; Olamaee, M; Rasooli, I; Akhavian, Tehrani A
2012-01-01
Background and Objectives Azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gram-negative soil bacterium capable of fixing nitrogen. Oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of A. vinelandii cultivation. This phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. The aim of this study was to design a simple strategy to explain the alginate production, cell growth and nitrogenase activity correlation in A. vinelandii under aerobic conditions. Material and Methods Thirty-five different soil samples were taken from the rhizosphere of agricultural crops of Iran. Enrichment and isolation strategies were employed for microbial isolation. Physiological and biochemical characteristics were determined. Molecular identification was performed using selective nifH-g1 primers. Alginate production and nitrogenase activity assay by each isolate of Azotobacter were carried out. Bacterial growth, alginate production and Nitrogenase activity were conducted by time-coursed quantitative measurements. Results Total of 26 isolates were selected after enrichment, isolation, and screening. The isolate was identified by molecular tests as A. vinelandii. The highest alginate productions of 1.02 g/l and 0.91g/l were noted after 4 days in 8 isolates, cell biomass of which were estimated 4.88-5.26 g/l. Six of 8 isolates were able to fix atmospheric N2 on nitrogen-free medium. Rates obtained in isolates were in the range of 12.1 to 326.4 nmol C2H4 h-1 vial-1. Conclusions Nitrogen fixation and alginate production yielded significant and positive Pearson's correlation coefficient of R2 = 0.760, p ∼ 0.02. Finally association between bacterial growth, alginate production and nitrogenase activity almost noticeable yielded significant and positive Pearson's correlation coefficient R2= 0.723, p ∼ 0.04. PMID:23066492
Ozone Correlative Measurements Workshop
NASA Technical Reports Server (NTRS)
Hilsenrath, E. (Editor)
1985-01-01
A study was conducted to determine the necessary parameters for the correlation of data on Earth ozone. Topics considered were: (1) measurement accuracy; (2) equipment considerations (SBUV); and (3) ground based measurements to support satellite data.
Extractable Work from Correlations
NASA Astrophysics Data System (ADS)
Perarnau-Llobet, Martí; Hovhannisyan, Karen V.; Huber, Marcus; Skrzypczyk, Paul; Brunner, Nicolas; Acín, Antonio
2015-10-01
Work and quantum correlations are two fundamental resources in thermodynamics and quantum information theory. In this work, we study how to use correlations among quantum systems to optimally store work. We analyze this question for isolated quantum ensembles, where the work can be naturally divided into two contributions: a local contribution from each system and a global contribution originating from correlations among systems. We focus on the latter and consider quantum systems that are locally thermal, thus from which any extractable work can only come from correlations. We compute the maximum extractable work for general entangled states, separable states, and states with fixed entropy. Our results show that while entanglement gives an advantage for small quantum ensembles, this gain vanishes for a large number of systems.
Photothermal absorption correlation spectroscopy.
Octeau, Vivien; Cognet, Laurent; Duchesne, Laurence; Lasne, David; Schaeffer, Nicolas; Fernig, David G; Lounis, Brahim
2009-02-24
Fluorescence correlation spectroscopy (FCS) is a popular technique, complementary to cell imaging for the investigation of dynamic processes in living cells. Based on fluorescence, this single molecule method suffers from artifacts originating from the poor fluorophore photophysics: photobleaching, blinking, and saturation. To circumvent these limitations we present here a new correlation method called photothermal absorption correlation spectroscopy (PhACS) which relies on the absorption properties of tiny nano-objects. PhACS is based on the photothermal heterodyne detection technique and measures akin FCS, the time correlation function of the detected signals. Application of this technique to the precise determination of the hydrodynamic sizes of different functionalized gold nanoparticles are presented, highlighting the potential of this method. PMID:19236070
Personality correlates of homophobia.
Johnson, M E; Brems, C; Alford-Keating, P
1997-01-01
This study explored the relationship between homophobia and several personality traits (empathy, religiosity, and coping style) in the context of respondents' gender and age. The sample consisted of 714 college students who responded to the Homophobia Attitude Scale (HAS) and personality trait scales. Results revealed that women endorsed fewer homophobic attitudes, beliefs, and behaviors than men and that age was negatively correlated with homophobia. Empathic concern and perspective taking were significantly correlated with lower overall homophobic attitudes, less affect discomfort in regard to gays, and less likelihood to abridge the human rights of gays. Religiosity was significantly correlated with more biased beliefs about the origins of homophobia, greater affective discomfort around gays, less endorsement of human rights for gays, and greater homophobia. Use of denial and isolation as coping styles were positively related to homophobia and use of turning against style was negatively correlated.
Correlation of diffusion tensor imaging parameters with neural status in Pott’s spine
Jain, Nikhil; Saini, Namita Singh; Kumar, Sudhir; Rajagopalan, Mukunth; Chakraborti, Kanti Lal; Jain, Anil Kumar
2016-01-01
Introduction: Diffusion tensor imaging (DTI) has been used in cervical trauma and spondylotic myelopathy, and it has been found to correlate with neural deficit and prognosticate neural recovery. Such a correlation has not been studied in Pott’s spine with paraplegia. Hence, this prospective study has been used to find correlation of DTI parameters with neural deficit in these patients. Methods: Thirty-four patients of spinal TB were enrolled and DTI was performed before the start of treatment and after six months. Fractional anisotropy (FA), Mean diffusivity (MD), and Tractography were studied. Neurological deficit was graded by the Jain and Sinha scoring. Changes in FA and MD at and below the site of lesion (SOL) were compared to above the SOL (control) using the unpaired t-test. Pre-treatment and post-treatment values were also compared using the paired t-test. Correlation of DTI parameters with neurological score was done by Pearson’s correlation. Subjective assessment of Tractography images was done. Results: Mean average FA was not significantly decreased at the SOL in patients with paraplegia as compared to control. After six months of treatment, a significant decrease (p = 0.02) in mean average FA at the SOL compared to pre-treatment was seen. Moderate positive correlation (r = 0.49) between mean average FA and neural score after six months of treatment was found. Tractography images were not consistent with severity of paraplegia. Conclusion: Unlike spondylotic myelopathy and trauma, epidural collection and its organized inflammatory tissue in Pott’s spine precludes accurate assessment of diffusion characteristics of the compressed cord. PMID:27163110
NASA Technical Reports Server (NTRS)
Kurihara, Shinobu; Nozawa, Kentaro
2013-01-01
The K5/VSSP software correlator (Figure 1), located in Tsukuba, Japan, is operated by the Geospatial Information Authority of Japan (GSI). It is fully dedicated to processing the geodetic VLBI sessions of the International VLBI Service for Geodesy and Astrometry. All of the weekend IVS Intensives (INT2) and the Japanese domestic VLBI observations organized by GSI were processed at the Tsukuba VLBI Correlator.
(111)In-exendin uptake in the pancreas correlates with the β-cell mass and not with the α-cell mass.
Brom, Maarten; Joosten, Lieke; Frielink, Cathelijne; Boerman, Otto; Gotthardt, Martin
2015-04-01
Targeting of the GLP-1 receptor with (111)In-labeled exendin is an attractive approach to determine the β-cell mass (BCM). Preclinical studies as well as a proof-of-concept study in type 1 diabetic patients and healthy subjects showed a direct correlation between BCM and radiotracer uptake. Despite these promising initial results, the influence of α-cells on the uptake of the radiotracer remains a matter of debate. In this study, we determined the correlation between pancreatic tracer uptake and β- and α-cell mass in a rat model for β-cell loss. The uptake of (111)In-exendin (% ID/g) showed a strong positive linear correlation with the BCM (Pearson r = 0.82). The fraction of glucagon-positive cells in the total endocrine mass was increased after alloxan treatment (26% ± 4%, 43% ± 8%, and 69% ± 21% for 0, 45, and 60 mg/kg alloxan, respectively). The uptake of (111)In-exendin showed a negative linear correlation with the α-cell fraction (Pearson r = -0.76). These data clearly indicate toward specificity of (111)In-exendin for β-cells and that the influence of the α-cells on (111)In-exendin uptake is negligible. PMID:25409700
(Dis)similarity Index To Compare Correlated Motions in Molecular Simulations.
Tiberti, Matteo; Invernizzi, Gaetano; Papaleo, Elena
2015-09-01
Molecular dynamics (MD) simulations are widely used to complement or guide experimental studies in the characterization of protein dynamics, thanks to improvements in force-field accuracy, along with in the software and hardware to sample the conformational landscape of proteins. Among the different applications of MD simulations, the study of correlated motions is largely employed for different purposes. Several metrics have been developed to describe correlated motions in the MD ensemble, such as methods based on Pearson Correlation or Mutual Information. Cross-correlation analysis of MD trajectories is indeed appealing not only to identify residues characterized by coupled fluctuations in protein structures but also since it can be used to extrapolate motions along directions in which major conformational changes should occur, for example on longer time scales than the ones that are actually simulated. Nevertheless, most of the MD studies employ average correlation maps and mostly in a qualitative way, even when different systems or different replicates of the same system are compared. The broad application of correlation metrics in the analysis of MD simulations, especially for comparative purposes, requires a step forward toward more quantitative and accurate comparisons. We thus here employed a simple but effective index, which is based on a normalized Frobenius norm of the differences between protein correlation maps, to compare correlated motions. We applied this index for a quantitative comparison of correlated motions from MD simulations of seven proteins of different size and fold. We also employed the index to assess the robustness of correlation description when multi-replicate MD simulations of a same system are used, and we compared our index to metrics for comparison of structural ensembles such as Root Mean Square Inner Product and the Bhattacharyya Coefficient. PMID:26575932
Standardized Pearson type 3 density function area tables
NASA Technical Reports Server (NTRS)
Cohen, A. C.; Helm, F. R.; Sugg, M.
1971-01-01
Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods.
Coefficients of Association Analogous to Pearson's r for Nonparametric Statistics.
ERIC Educational Resources Information Center
Stavig, Gordon; Acock, Alan C.
1980-01-01
Two r coefficients of association are discussed. One of the coefficients can be applied to any nonparametric test statistic (NTS) in which a normal approximation equation is appropriate. The other coefficient is applicable to any NTS in which exact probabilities are known. (Author/RL)
Genetics Home Reference: Pearson marrow-pancreas syndrome
... within cells that use oxygen to convert the energy from food into a form cells can use. This process is called oxidative phosphorylation . Although most DNA is packaged in chromosomes within the nucleus (nuclear DNA), mitochondria also have a small amount of ...
NASA Astrophysics Data System (ADS)
Ruigrok, Elmer; Gibbons, Steven; Wapenaar, Kees
2016-10-01
An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.
Geometrically representing spin correlations
NASA Astrophysics Data System (ADS)
White, Ian G.; Mirasola, Anthony; Hollingsworth, Jacob; Mukherjee, Rick; Hazzard, Kaden R. A.
2016-05-01
We develop a general method to visualize spin correlations, and we demonstrate its usefulness in ultracold matter from fermions in lattices to trapped ions and ultracold molecules. Correlations are of fundamental interest in many-body physics: they characterize phases in condensed matter and AMO, and are required for quantum sensing and computing. However, it is often difficult to understand even the simplest correlations - for example between two spin-1/2's - directly from the components Cab =
Slit2 expression and its correlation with subcellular localization of β-catenin in gastric cancer.
Shi, Rongliang; Liu, Weiyan; Liu, Bingya; Xu, Ziping; Chen, Liping; Zhang, Ziping
2013-10-01
Gastric cancer is the fourth most common cancer worldwide. Several signaling pathways are involved in gastric cancer development and progression. Slit2 was recently found to be involved in cancer; however, its expression pattern in gastric cancer has not been discovered yet. In the present study, we investigated the expression of Slit2 in human gastric cancer and its correlation with the expression and subcellular localization of β-catenin. Immunohistochemistry (IHC) staining revealed that Slit2 was highly expressed in human gastric cancer tissues, while it was low or weakly expressed in normal gastric tissues. The differences in clinicopathological features between different groups were determined using Pearson's χ2 test. Slit2 levels were significantly associated with differentiation, Lauren's classification, lymph node metastasis and TNM staging. Slit2 levels were positively correlated with β-catenin level in gastric cancer tissues and cell lines. High levels of Slit2 were correlated with the membrane localization of β-catenin, and low levels of Slit2 were correlated with nuclear translocation of β-catenin in both gastric cancer tissues and cell lines assayed by IHC and immunofluorescence staining, respectively. Our data suggest that Slit2 was highly expressed in gastric cancer patients with less advanced clinicopathological features. Slit2 levels were correlated with β-catenin level and subcellular localization.
Correlation of the Y-Balance Test with Lower-limb Strength of Adult Women.
Lee, Dong-Kyu; Kim, Gyoung-Mo; Ha, Sung-Min; Oh, Jae-Seop
2014-05-01
[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.
Correlates of the health statuses of the faculty at midlife
Galeon, Galvin Alaan
2016-01-01
Background: Between the school years of 2009-2012, the turnover record of the University of San Jose-Recoletos (USJ-R), Cebu City, Philippines showed that permanent faculty members who left the institution were all midlifers. Their reasons varied from health issues to greener pasture elsewhere. Materials and Methods: This study then sought to explore the health statuses of the faculty midlifers of the USJ-R. The data were collected through survey conducted among the 106 faculty midlifers of the university. This study applied multivariate analyses to the survey data using Pearson-moment of correlation to determine the relationship between the sociodemographic profile of the research participants and their health statuses. Results: This research revealed that faculty midlifers are generally well physically. They showed emotional maturity and have positive outlook toward midlife. More so, their health conditions are significantly related with their sex, age, years of teaching, educational attainment, and income. Conclusion: At midlife, the faculty members of USJ-R can still generally be considered physically well. Thus, if they are well-managed, they can become relevant and better contributors to the attainment of the basic goals and objectives of the educational institution and the educational system in general. PMID:27134476
Target detection from dual disparate sonar platforms using canonical correlations
NASA Astrophysics Data System (ADS)
Azimi-Sadjdadi, Mahmood R.; Tucker, J. Derek
2008-04-01
In this paper a new coherence-based feature extraction method for sonar imagery generated from two disparate sonar systems is developed. Canonical correlation analysis (CCA) is employed to identify coherent information from co-registered regions of interest (ROI's) that contain target activities, while at the same time extract useful coherent features from both images. The extracted features can be used for simultaneous detection and classification of target and non-target objects in the sonar images. In this study, a side-scan sonar that provides high resolution images with good target definition and a broadband sonar that generates low resolution images, but with reduced background clutter. The optimum Neyman-Pearson detector will be presented and then extended to the dual sensor platform scenarios. Test results of the proposed methods on a dual sonar imagery data set provided by the Naval Surface Warfare Center (NSWC) Panama City, FL will be presented. This database contains co-registered pair of images over the same target field with varying degree of detection difficulty and bottom clutter. The effectiveness of CCA as the optimum detection tool is demonstrated in terms of probability of detection and false alarm rate.
NASA Astrophysics Data System (ADS)
Ziegler, A.; Metzler, A.; Köckenberger, W.; Izquierdo, M.; Komor, E.; Haase, A.; Décorps, M.; von Kienlin, M.
1996-08-01
Identification and quantitation in conventional1H spectroscopic imagingin vivois often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean (Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, β-glucose, glutamine/glutamate, lysine, and arginine.
Advanced quantum noise correlations
NASA Astrophysics Data System (ADS)
Vogl, Ulrich; Glasser, Ryan T.; Clark, Jeremy B.; Glorieux, Quentin; Li, Tian; Corzo, Neil V.; Lett, Paul D.
2014-01-01
We use the quantum correlations of twin beams of light to investigate the fundamental addition of noise when one of the beams propagates through a fast-light medium based on phase-insensitive gain. The experiment is based on two successive four-wave mixing processes in rubidium vapor, which allow for the generation of bright two-mode-squeezed twin beams followed by a controlled advancement while maintaining the shared quantum correlations between the beams. The demonstrated effect allows the study of irreversible decoherence in a medium exhibiting anomalous dispersion, and for the first time shows the advancement of a bright nonclassical state of light. The advancement and corresponding degradation of the quantum correlations are found to be operating near the fundamental quantum limit imposed by using a phase-insensitive amplifier.
Correlation among auto-refractor, wavefront aberration, and subjective manual refraction
NASA Astrophysics Data System (ADS)
Li, Qi; Ren, Qiushi
2005-01-01
Three optometry methods which include auto-refractor, wavefront aberrometer and subjective manual refraction were studied and compared in measuring low order aberrations of 60 people"s 117 normal eyes. Paired t-test and linear regression were used to study these three methods" relationship when measuring myopia with astigmatism. In order to make the analysis more clear, we divided the 117 normal eyes into different groups according to their subjective manual refraction and redid the statistical analysis. Correlations among three methods show significant in sphere, cylinder and axis in all groups, with sphere"s correlation coefficients largest(R>0.98, P<0.01) and cylinder"s smallest (0.90
NASA Astrophysics Data System (ADS)
Romney, J. D.
1995-05-01
The VLBA correlator has been operational for somewhat more than a year. Since the beginning of 1995, it has operated at 54% efficiency (i.e., that fraction of scheduled production time leads directly to finished results). After correcting for effects of the playback speedup and the part-time production schedule, this corresponds to a 39% net operational efficiency of the VLBA instrument over the same interval. The current operational system includes most of the capabilities originally planned for the correlator's initial configuration. Two important exceptions could not be included: narrowband (less than 250 kHz bandwidth) spectroscopy, and various forms of sub-arraying. On the other hand, two capabilities not planned until later have been achieved: cross-polarized correlation and an extremely accurate fringe model. Parts of the real-time control software are currently being rewritten. The goals of this effort are both scientific, including support for narrowband and sub-arrayed observations, and technical, providing a more secure basis for development of additional capabilities in future phases. Among the most promising of these later features is a frequency-dependent signal gate, which will enable gated, de-dispersed interferometry of pulsars. The correlator is a 20-station system, capable of processing data rates up to the VLBA's maximicrons of 512 Mbit/s, with spectral resolution up to 2048 points per baseline. Its design is based on an ``FX'' architecture, performing a fast Fourier transform operation on segmented input signal streams, followed by a pointwise cross-multiplication operation and subsequent integration. This approach makes possible a relatively inexpensive, flexible yet simple hardware organization, and in turn a fairly simple structure of the control software. It provides several enhancements of sensitivity relative to a conventional lag correlator. Facilities included in the VLBA array and correlator for dealing with the less favorable aspects
Correlation ion mobility spectroscopy
Pfeifer, Kent B.; Rohde, Steven B.
2008-08-26
Correlation ion mobility spectrometry (CIMS) uses gating modulation and correlation signal processing to improve IMS instrument performance. Closely spaced ion peaks can be resolved by adding discriminating codes to the gate and matched filtering for the received ion current signal, thereby improving sensitivity and resolution of an ion mobility spectrometer. CIMS can be used to improve the signal-to-noise ratio even for transient chemical samples. CIMS is especially advantageous for small geometry IMS drift tubes that can otherwise have poor resolution due to their small size.
Correlations for the Stroop Color and Word Test with measures of reading and language achievement.
Leverett, J Patrick; Lassiter, Kerry S; Buchanan, Gray M
2002-04-01
The present investigation examined the relationships for scores on the Stroop Color and Word Test with measures of reading and language achievement within an adult population. The Stroop Color and Word Test, Nelson-Denny Reading Test, Woodcock-Johnson Psycho-Educational Battery-Revised, and Wide Range Achievement Test-3 were administered to 99 men ranging in age from 18 to 27 years. Pearson product-moment correlations indicated that the Stroop Word task was positively associated with scores on the WRAT-3 Spelling task, the Woodcock-Johnson Basic and Broad Reading tasks, and the Nelson-Denny Rcading Rate and Comprehension tasks. These and other significant relationships were discussed in terms of possible implications regarding the assessment of reading achievement.
Detrended fluctuation analysis made flexible to detect range of cross-correlated fluctuations
NASA Astrophysics Data System (ADS)
Kwapień, Jarosław; Oświecimka, Paweł; DroŻdŻ, Stanisław
2015-11-01
The detrended cross-correlation coefficient ρDCCA has recently been proposed to quantify the strength of cross-correlations on different temporal scales in bivariate, nonstationary time series. It is based on the detrended cross-correlation and detrended fluctuation analyses (DCCA and DFA, respectively) and can be viewed as an analog of the Pearson coefficient in the case of the fluctuation analysis. The coefficient ρDCCA works well in many practical situations but by construction its applicability is limited to detection of whether two signals are generally cross-correlated, without the possibility to obtain information on the amplitude of fluctuations that are responsible for those cross-correlations. In order to introduce some related flexibility, here we propose an extension of ρDCCA that exploits the multifractal versions of DFA and DCCA: multifractal detrended fluctuation analysis and multifractal detrended cross-correlation analysis, respectively. The resulting new coefficient ρq not only is able to quantify the strength of correlations but also allows one to identify the range of detrended fluctuation amplitudes that are correlated in two signals under study. We show how the coefficient ρq works in practical situations by applying it to stochastic time series representing processes with long memory: autoregressive and multiplicative ones. Such processes are often used to model signals recorded from complex systems and complex physical phenomena like turbulence, so we are convinced that this new measure can successfully be applied in time-series analysis. In particular, we present an example of such application to highly complex empirical data from financial markets. The present formulation can straightforwardly be extended to multivariate data in terms of the q -dependent counterpart of the correlation matrices and then to the network representation.
NASA Astrophysics Data System (ADS)
Moore, C. S.; Wood, T. J.; Saunderson, J. R.; Beavis, A. W.
2015-12-01
This work assessed the appropriateness of the signal-to-noise ratio improvement factor (KSNR) as a metric for the optimisation of computed radiography (CR) of the chest. The results of a previous study in which four experienced image evaluators graded computer simulated chest images using a visual grading analysis scoring (VGAS) scheme to quantify the benefit of using an anti-scatter grid were used for the clinical image quality measurement (number of simulated patients = 80). The KSNR was used to calculate the improvement in physical image quality measured in a physical chest phantom. KSNR correlation with VGAS was assessed as a function of chest region (lung, spine and diaphragm/retrodiaphragm), and as a function of x-ray tube voltage in a given chest region. The correlation of the latter was determined by the Pearson correlation coefficient. VGAS and KSNR image quality metrics demonstrated no correlation in the lung region but did show correlation in the spine and diaphragm/retrodiaphragmatic regions. However, there was no correlation as a function of tube voltage in any region; a Pearson correlation coefficient (R) of -0.93 (p = 0.015) was found for lung, a coefficient (R) of -0.95 (p = 0.46) was found for spine, and a coefficient (R) of -0.85 (p = 0.015) was found for diaphragm. All demonstrate strong negative correlations indicating conflicting results, i.e. KSNR increases with tube voltage but VGAS decreases. Medical physicists should use the KSNR metric with caution when assessing any potential improvement in clinical chest image quality when introducing an anti-scatter grid for CR imaging, especially in the lung region. This metric may also be a limited descriptor of clinical chest image quality as a function of tube voltage when a grid is used routinely.
ERIC Educational Resources Information Center
Matthews, Doris B.
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)…
Neuroanatomical Correlates of Intelligence
ERIC Educational Resources Information Center
Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.
2009-01-01
With the advancement of image acquisition and analysis methods in recent decades, unique opportunities have emerged to study the neuroanatomical correlates of intelligence. Traditional approaches examining global measures have been complemented by insights from more regional analyses based on pre-defined areas. Newer state-of-the-art approaches…
Correlational Comparison in English
ERIC Educational Resources Information Center
Smith, Elizabeth Allyn
2011-01-01
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…
CMB Lensing Cross Correlations
NASA Astrophysics Data System (ADS)
Bleem, Lindsey
2014-03-01
A new generation of experiments designed to conduct high-resolution, low-noise observations of the Cosmic Microwave Background (CMB)--including ACTpol, Planck, POLARBEAR and SPTpol--are producing exquisite measurements of the gravitational lensing of the CMB. Such measurements, covering large fractions of the sky, provide detailed maps of the projected mass distribution extending to the surface of the CMB's last scattering. Concurrently, a large number of deep, wide-area imaging and spectroscopic surveys (e.g., the Dark Energy Survey (DES),WISE all-sky survey, Subaru HyperSuprimeCam Survey, LSST, MS-DESI, BigBoss, etc.) are, or will soon be, providing maps of the distribution of galaxies in the Universe. Correlations of such tracer populations with lensing data allows new probes of where and how galaxies form in the dark matter skeleton of the Universe. Recent correlations of maps of galaxy and quasar densities with lensing convergence maps have produced significant measurements of galaxy bias. The near-term prospect for improvements in such measurements is notable as more precise lensing data from CMB polarization experiments will help to break cosmological and astrophysical parameter degeneracies. Work by the Planck, SPT, and POLARBEAR collaborations has also focused on the correlation of the Cosmic Infrared Background (CIB) with CMB lensing convergence maps. This correlation is particularly strong as the redshifts of the CIB and CMB lensing kernel are well matched. Such correlations probe high-redshift structure, constraining models of star-formation and the characteristic mass scale for halos hosting CIB galaxies and have also been used to demonstrate the first detection of CMB B-mode polarization--an important milestone in CMB observations. Finally, combining galaxy number density, cosmic shear and CMB lensing maps has the potential to provide valuable systematic tests for upcoming cosmological results from large optical surveys such as LSST.
Pereira, Leani Souza Máximo; Narciso, Fabrícia Mendes Silva; Oliveira, Daniela Matos Garcia; Coelho, Fernanda Matos; Souza, Danielle da Glória de; Dias, Rosângela Corrêa
2009-01-01
Sarcopenia is a loss of muscle mass related to aging and leads to muscle performance decline. An increase in inflammatory mediator levels, especially of IL-6, has been associated to reduced muscle strength in the elderly. The aim of the present cross-sectional study was to correlate IL-6 plasma levels with manual muscle strength (MMS) in 63 community-dwelling elderly women. (71.2+/-7.4years). IL-6 was measured using enzyme-linked immunosorbent assay (ELISA) and MMS was measured using the JAMAR dynamometer. Pearson's test was used to explore the relationship between the outcomes at the significance level of alpha=0.05. IL-6 levels (2.56+/-3.44pg/ml) and MMS (22.86+/-4.62kgf) exhibited an inverse correlation (r=-0.2673 and p=0.0373). The increase in IL-6 plasma levels possibly contributed toward the reduction in manual muscle strength among the elderly women studied.
From micro-correlations to macro-correlations
NASA Astrophysics Data System (ADS)
Eliazar, Iddo
2016-11-01
Random vectors with a symmetric correlation structure share a common value of pair-wise correlation between their different components. The symmetric correlation structure appears in a multitude of settings, e.g. mixture models. In a mixture model the components of the random vector are drawn independently from a general probability distribution that is determined by an underlying parameter, and the parameter itself is randomized. In this paper we study the overall correlation of high-dimensional random vectors with a symmetric correlation structure. Considering such a random vector, and terming its pair-wise correlation "micro-correlation", we use an asymptotic analysis to derive the random vector's "macro-correlation" : a score that takes values in the unit interval, and that quantifies the random vector's overall correlation. The method of obtaining macro-correlations from micro-correlations is then applied to a diverse collection of frameworks that demonstrate the method's wide applicability.
Macular pigment optical density: repeatability, intereye correlation, and effect of ocular dominance
Davey, Pinakin Gunvant; Alvarez, Silverio D; Lee, Jessica Y
2016-01-01
Purpose To evaluate short-term repeatability, intereye correlation, and effect of ocular dominance on macular pigment optical density (MPOD) measurements obtained using the QuantifEye Heterochromatic Flicker Photometer. Patients and methods A total of 72 study participants were enrolled in this prospective, cross-sectional study. Participants underwent a comprehensive ocular evaluation, including visual acuity, evaluation of ocular dominance, slit lamp examination, intraocular pressure measurement, and optic nerve head and macula analysis using optical coherence tomography and fundus photography. All study participants after initial training underwent MPOD measurement twice in both eyes in a randomized sequence. The repeatability was tested using Altman and Bland plots for first measurements with the second measurements for right eye and left eye and additionally by grouping eyes as a function of ocular dominance. The Pearson correlation coefficient was performed to assess the intereye correlation of MPOD values. Results The mean age of study participants was 35.5 years (range 22–68 years). The mean MPOD measurements for OD (right eye) and OS (left eye) were 0.47 and 0.48, respectively, which followed a normal distribution (Shapiro–Wilk test, P=0.6 and 0.2). The 95% limits of agreement of Altman and Bland plots for the first and second measurements were −0.12 to +0.11 and −0.13 to +0.12 for OD and OS, respectively. The correlation coefficient of mean MPOD measurements of OD and OS was r statistic =0.94 (Pearson correlation coefficient P<0.0001; r2 0.89). The 95% limits of agreement of Altman and Bland plots when evaluated by laterality of eye or by ocular dominance were narrow, with limits of agreement ranging from −0.13 to +0.12. Conclusion The MPOD measurements obtained using the QuantifEye show good short-term repeatability. There is excellent intereye correlation, indicating that the MPOD values of one eye data can predict the fellow eye value with 89
Macular pigment optical density: repeatability, intereye correlation, and effect of ocular dominance
Davey, Pinakin Gunvant; Alvarez, Silverio D; Lee, Jessica Y
2016-01-01
Purpose To evaluate short-term repeatability, intereye correlation, and effect of ocular dominance on macular pigment optical density (MPOD) measurements obtained using the QuantifEye Heterochromatic Flicker Photometer. Patients and methods A total of 72 study participants were enrolled in this prospective, cross-sectional study. Participants underwent a comprehensive ocular evaluation, including visual acuity, evaluation of ocular dominance, slit lamp examination, intraocular pressure measurement, and optic nerve head and macula analysis using optical coherence tomography and fundus photography. All study participants after initial training underwent MPOD measurement twice in both eyes in a randomized sequence. The repeatability was tested using Altman and Bland plots for first measurements with the second measurements for right eye and left eye and additionally by grouping eyes as a function of ocular dominance. The Pearson correlation coefficient was performed to assess the intereye correlation of MPOD values. Results The mean age of study participants was 35.5 years (range 22–68 years). The mean MPOD measurements for OD (right eye) and OS (left eye) were 0.47 and 0.48, respectively, which followed a normal distribution (Shapiro–Wilk test, P=0.6 and 0.2). The 95% limits of agreement of Altman and Bland plots for the first and second measurements were −0.12 to +0.11 and −0.13 to +0.12 for OD and OS, respectively. The correlation coefficient of mean MPOD measurements of OD and OS was r statistic =0.94 (Pearson correlation coefficient P<0.0001; r2 0.89). The 95% limits of agreement of Altman and Bland plots when evaluated by laterality of eye or by ocular dominance were narrow, with limits of agreement ranging from −0.13 to +0.12. Conclusion The MPOD measurements obtained using the QuantifEye show good short-term repeatability. There is excellent intereye correlation, indicating that the MPOD values of one eye data can predict the fellow eye value with 89
Correlates of financial satisfaction.
Hsieh, C M
2001-01-01
The objectives of this study are to 1) assess the effects of major correlates of global subjective well-being on financial satisfaction, and 2) use empirical data to present the consequences of violating basic regression assumptions. Analyzing data from the General Social Surveys, 1972-1996 (Davis & Smith, 1996a) this study found that among Americans age forty-five and above, most of the major correlates of global subjective well-being show similar effects on financial satisfaction. The study's findings confirm a nonlinear effect of income on financial satisfaction. Comparing results from different analytical methods, this study also alerts researchers to the importance of taking into account the level of measurements of study variables, which have tended to be overlooked by previous subjective well-being research.
Digital demodulator-correlator
NASA Technical Reports Server (NTRS)
Layland, J. W.; Martin, W. L.; Zygielbaum, A. I.; Goldstein, R. M.; Hubbard, W. P. (Inventor)
1978-01-01
An apparatus for demodulation and correlation of a code modulated 10 MHz signal is presented. The apparatus is comprised of a sample and hold analog-to-digital converter synchronized by a frequency coherent 40 MHz pulse to obtain four evenly spaced samples of each of the signal. Each sample is added or subtracted to or from one of four accumulators to or from the separate sums. The correlation functions are then computed. As a further feature of the invention, multipliers are each multiplied by a squarewave chopper signal having a period that is long relative to the period of the received signal to foreclose contamination of the received signal by leakage from either of the other two terms of the multipliers.
Correlators in nontrivial backgrounds
Mello Koch, Robert de; Ives, Norman; Stephanou, Michael
2009-01-15
Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.
Correlation, coherence and context
NASA Astrophysics Data System (ADS)
Eberly, J. H.
2016-08-01
The modern theory of coherence is based on correlation functions. A generic example could be written < {{V}\\ast}≤ft({{t}1}\\right)V≤ft({{t}2}\\right)> , denoting an average of products of the values of a signal V(t) at two specified times. Here we infer that t is a degree of freedom that the signal depends on. Typically, physical variables depend on more than one degree of freedom, and recognition of this has prompted attention to some interesting questions for the correlation functions and the several coherences that can be attributed to the same optical field. We examine some of the questions arising from the standpoint of experimental contexts. Degree of polarizability and degree of entanglement (classical non-separability) can serve as starting points for quantitative assignments.
DD correlations in photoproduction
NASA Astrophysics Data System (ADS)
Alvarez, M. P.; Barate, R.; Bloch, D.; Bonamy, P.; Borgeaud, P.; Burchell, M.; Burmeister, H.; Brunet, J. M.; Calvino, F.; Cattaneo, M.; Crespo, J. M.; D'Almagne, B.; David, M.; di Ciaccio, L.; Dixon, J.; Druet, P.; Duane, A.; Engel, J. P.; Ferrer, A.; Filippas, T. A.; Fokitis, E.; Forty, R. W.; Foucault, P.; Gazis, E. N.; Gerber, J. P.; Giomataris, Y.; Hofmokl, T.; Katsoufis, E. C.; Koratzinos, M.; Krafft, C.; Lefievre, B.; Lemoigne, Y.; Lopez, A.; Lui, W. K.; Magneville, C.; Maltezos, A.; McEwen, J. G.; Papadopoulou, T.; Pattison, B.; Poutot, D.; Primout, M.; Rahmani, H.; Roudeau, P.; Seez, C.; Six, J.; Strub, R.; Treille, D.; Triscos, P.; Tristram, G.; Villet, G.; Volte, A.; Wayne, M.; Websdale, D. M.; Wormser, G.; Zolnierowski, Y.
1992-03-01
Kinematic correlations between the charmed D and D mesons produced by a photon beam of mean energy 100 GeV/c have been measured by the NA14/2 experiment at CERN using a sample of almost background-free fully reconstructed DD events. The observed D and DD distributions are compared to the predictions of production models using different parameters for the charm fragmentation function and for the intrinsic transverse momentum of the partons.
An Examination of Correlations between MMI scores and Pharmacy School GPA
Dell, Kamila; Rodriguez-Snapp, Nazach; Petrelli, Heather M.W.
2016-01-01
Objective. To investigate the correlation of mean admission multiple mini-interview (MMI) scores with cumulative and overall GPA across didactic years 1-3 in the doctor of pharmacy (PharmD) curriculum. Methods. The mean admission MMI score and cumulative and overall GPA for first year (P1), second year (P2), and third year (P3) students in the PharmD curriculum was used to conduct a multiple regression analysis and to calculate a Pearson correlation coefficient. Statistical analysis was performed using SPSS, v20. Results. A negative correlation between mean admission MMI and overall GPA was observed for P1 students and P2 students. A significant positive correlation was observed between mean admission MMI and overall GPA for P3 students. Conclusion. A weak association between mean admission MMI score and GPA was observed, and the direction of the association between MMI and GPA was mixed across cohorts of students in the PharmD curriculum. Further research is needed that includes measurement of noncognitive outcomes and continued validation of the MMI for use in pharmacy school admissions. PMID:27667835
An Examination of Correlations between MMI scores and Pharmacy School GPA
Dell, Kamila; Rodriguez-Snapp, Nazach; Petrelli, Heather M.W.
2016-01-01
Objective. To investigate the correlation of mean admission multiple mini-interview (MMI) scores with cumulative and overall GPA across didactic years 1-3 in the doctor of pharmacy (PharmD) curriculum. Methods. The mean admission MMI score and cumulative and overall GPA for first year (P1), second year (P2), and third year (P3) students in the PharmD curriculum was used to conduct a multiple regression analysis and to calculate a Pearson correlation coefficient. Statistical analysis was performed using SPSS, v20. Results. A negative correlation between mean admission MMI and overall GPA was observed for P1 students and P2 students. A significant positive correlation was observed between mean admission MMI and overall GPA for P3 students. Conclusion. A weak association between mean admission MMI score and GPA was observed, and the direction of the association between MMI and GPA was mixed across cohorts of students in the PharmD curriculum. Further research is needed that includes measurement of noncognitive outcomes and continued validation of the MMI for use in pharmacy school admissions.
A comment on the rank correlation merit function for 2D/3D registration
NASA Astrophysics Data System (ADS)
Figl, Michael; Bloch, Christoph; Birkfellner, Wolfgang
2010-02-01
Lots of procedures in computer assisted interventions register pre-interventionally generated 3D data sets to the intraoperative situation using fast and simply generated 2D images, e.g. from a C-Arm, a B-mode Ultrasound, etc. Registration is typically done by generating a 2D image out of the 3D data set, comparison to the original 2D image using a planar similarity measure and subsequent optimisation. As these two images can be very different, a lot of different comparison functions are in use. In a recent article Stochastic Rank Correlation, a merit function based on Spearman's rank correlation coefficient was presented. By comparing randomly chosen subsets of the images, the authors wanted to avoid the computational expense of sorting all the points in the image. In the current paper we show that, because of the limited grey level range in medical images, full image rank correlation can be computed almost as fast as Pearson's correlation coefficient. A run time estimation is illustrated with numerical results using a 2D Shepp-Logan phantom at different sizes, and a sample data set of a pig.
Pernet, Cyril R; Wilcox, Rand; Rousselet, Guillaume A
2012-01-01
Pearson's correlation measures the strength of the association between two variables. The technique is, however, restricted to linear associations and is overly sensitive to outliers. Indeed, a single outlier can result in a highly inaccurate summary of the data. Yet, it remains the most commonly used measure of association in psychology research. Here we describe a free Matlab((R)) based toolbox (http://sourceforge.net/projects/robustcorrtool/) that computes robust measures of association between two or more random variables: the percentage-bend correlation and skipped-correlations. After illustrating how to use the toolbox, we show that robust methods, where outliers are down weighted or removed and accounted for in significance testing, provide better estimates of the true association with accurate false positive control and without loss of power. The different correlation methods were tested with normal data and normal data contaminated with marginal or bivariate outliers. We report estimates of effect size, false positive rate and power, and advise on which technique to use depending on the data at hand.
An Examination of Correlations between MMI scores and Pharmacy School GPA.
Cowart, Kevin; Dell, Kamila; Rodriguez-Snapp, Nazach; Petrelli, Heather M W
2016-08-25
Objective. To investigate the correlation of mean admission multiple mini-interview (MMI) scores with cumulative and overall GPA across didactic years 1-3 in the doctor of pharmacy (PharmD) curriculum. Methods. The mean admission MMI score and cumulative and overall GPA for first year (P1), second year (P2), and third year (P3) students in the PharmD curriculum was used to conduct a multiple regression analysis and to calculate a Pearson correlation coefficient. Statistical analysis was performed using SPSS, v20. Results. A negative correlation between mean admission MMI and overall GPA was observed for P1 students and P2 students. A significant positive correlation was observed between mean admission MMI and overall GPA for P3 students. Conclusion. A weak association between mean admission MMI score and GPA was observed, and the direction of the association between MMI and GPA was mixed across cohorts of students in the PharmD curriculum. Further research is needed that includes measurement of noncognitive outcomes and continued validation of the MMI for use in pharmacy school admissions. PMID:27667835
Yan, Qinling; Tang, Sanyi; Gabriele, Sandra; Wu, Jianhong
2016-02-01
News reporting has the potential to modify a community's knowledge of emerging infectious diseases and affect peoples' attitudes and behavior. Here we developed a quantitative approach to evaluate the effects of media on such behavior. Statistically significant correlations between the number of new hospital notifications, during the 2009 A/H1N1 influenza epidemic in the Shaanxi province of China, and the number of daily news items added to eight major websites were found from Pearson correlation and cross-correlation analyses. We also proposed a novel model to examine the implication for transmission dynamics of these correlations. The model incorporated the media impact function into the intensity of infection, and enhanced the traditional epidemic SEIR model with the addition of media dynamics. We used a nonlinear least squares estimation to identify the best-fit parameter values in the model from the observed data. We also carried out the uncertainty and sensitivity analyses to determine key parameters during early phase of the disease outbreak for the final outcome of the outbreak with media impact. The findings confirm the importance of responses by individuals to the media reports, with behavior changes having important consequence for the emerging infectious disease control. Therefore, for mitigating emerging infectious diseases, media reports should be focused on how to guide people's behavioral changes, which are critical for limiting the spread of disease. PMID:26582723
Stature and gender determination and their correlation using odontometry and skull anthropometry
Gupta, Amit; Kumar, Kiran; Shetty, Devi Charan; Wadhwan, Vijay; Jain, Anshi; Khanna, Kaveri Surya
2014-01-01
Background: When the body has been mutilated, it is common to have the extremities or head amputated from the trunk. In concern with forensic odontology, an estimate must have been made based on the correlation of osteometry along with odontometry in determining sex, race and stature. Objective: The objective of this study is to investigate and correlate height and gender from odontometry and anthropometric data of the skull. Materials and Methods: The study was conducted in the Department of Oral and Maxillofacial Pathology and Microbiology, I.T.S Center for Dental studies and Research, Muradnagar, Ghaziabad (UP) with the representative study subjects of 60 patients as 30 males and 30 females in the age group of 15-25 years. The selected parameters were measured and then correlated to investigate stature and gender from odontometry and anthropometric data of the skull. Results: On linear regression analysis, the selected parameters were found to be statistically significant predictor of height. It was also established by Karl Pearson's coefficient correlation that the left mandibular canine index for female was statistically significant to show sexual dimorphism. Conclusion: In the emerging field of forensic odontology, skull anthropometry, odontometry exhibits stature determination and strong sexual dimorphism. PMID:25125917
Yan, Qinling; Tang, Sanyi; Gabriele, Sandra; Wu, Jianhong
2016-02-01
News reporting has the potential to modify a community's knowledge of emerging infectious diseases and affect peoples' attitudes and behavior. Here we developed a quantitative approach to evaluate the effects of media on such behavior. Statistically significant correlations between the number of new hospital notifications, during the 2009 A/H1N1 influenza epidemic in the Shaanxi province of China, and the number of daily news items added to eight major websites were found from Pearson correlation and cross-correlation analyses. We also proposed a novel model to examine the implication for transmission dynamics of these correlations. The model incorporated the media impact function into the intensity of infection, and enhanced the traditional epidemic SEIR model with the addition of media dynamics. We used a nonlinear least squares estimation to identify the best-fit parameter values in the model from the observed data. We also carried out the uncertainty and sensitivity analyses to determine key parameters during early phase of the disease outbreak for the final outcome of the outbreak with media impact. The findings confirm the importance of responses by individuals to the media reports, with behavior changes having important consequence for the emerging infectious disease control. Therefore, for mitigating emerging infectious diseases, media reports should be focused on how to guide people's behavioral changes, which are critical for limiting the spread of disease.
Canella, Richard Prazeres; Adam, Guilherme Pradi; de Castillo, Roberto André Ulhôa; Codonho, Daniel; Ganev, Gerson Gandhi; de Vicenzi, Luiz Fernando
2016-01-01
Objective To correlate the angles between the acetabulum and the proximal femur in symptomatic patients with femoroacetabular impingement (FAI), using computed tomography (CT). Methods We retrospectively evaluated 103 hips from 103 patients, using multislice CT to measure the acetabular age, acetabular version (in its supraequatorial portion and in its middle third), femoral neck version, cervical-diaphyseal and alpha angles and the acetabular depth. For the statistical analysis, we used the Pearson correlation coefficient. Results There were inverse correlations between the following angles: (1) acetabular coverage versus alpha angle (p = 0.019); (2) acetabular version (supraequatorial) versus alpha angle (p = 0.049). For patients with femoral anteversion lower than 15 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.026); (2) acetabular version (middle third) versus alpha angle (p = 0.02). For patients with acetabular version (supraequatorial) lower than 10 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.004); (2) acetabular version (middle third) versus alpha angle (p = 0.009). Conclusion There was a statistically significant inverse correlation between the acetabular version and alpha angles (the smaller the acetabular anteversion angle was, the larger the alpha angle was) in symptomatic patients, thus supporting the hypothesis that FAI occurs when cam and pincer findings due to acetabular retroversion are seen simultaneously, and that the latter alone does not cause FAI, which leads to overdiagnosis in these cases. PMID:27069890
Correlation between morphology and function of the upper lip: a longitudinal evaluation.
Ambrosio, Aldrieli Regina; Trevilatto, Paula Cristina; Sakima, Tatsuko; Ignácio, Sérgio Aparecido; Shimizu, Roberto Hideo
2009-06-01
In order to evaluate the relationship between the morphology of the upper lip and muscle activity in a sample of 38 subjects (17 males and 21 females) with Angle Class II division 1 malocclusions, cephalometric and electromyographic analyses were conducted. The sample was subdivided into either predominantly nose or mouth breathers. The individuals were evaluated at two different periods, with a 2 year interval. At the first observation, the subjects were 11 years to 14 years 11 months of age and at the second observation, 13 years 4 months to 16 years 6 months of age. Height and thickness of the upper lip were measured on lateral cephalograms with the aid of a digital pachymeter. For each individual, electromyographic records were obtained of the orbicularis oris superior muscle at rest and in a series of 12 movements. The electromyographic data were normalized as a function of amplitude, for achievement of the percentage value of each movement. Pearson and Spearman correlation tests were applied. The results showed some correlation between morphology and muscle function (at a confidence level of 95 per cent). However, as the values of the correlation coefficient (r) were too low to establish associations between variables, it was concluded that the dimensions of the upper lip are not correlated with muscle activity.
Neural correlates of gratitude.
Fox, Glenn R; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others.
2013-08-02
CorAL is a software Library designed to aid in the analysis of femtoscipic data. Femtoscopic data are a class of measured quantities used in heavy-ion collisions to characterize particle emitting source sizes. The most common type of this data is two-particle correleations induced by the Hanbury-Brown/Twiss (HBT) Effect, but can also include correlations induced by final-state interactions between pairs of emitted particles in a heavy-ion collision. Because heavy-ion collisions are complex many particle systems, modeling hydrodynamical models or hybrid techniques. Using the CRAB module, CorAL can turn the output from these models into something that can be directley compared to experimental data. CorAL can also take the raw experimentally measured correlation functions and image them by inverting the Koonin-Pratt equation to extract the space-time emission profile of the particle emitting source. This source function can be further analyzed or directly compared to theoretical calculations.
Neural correlates of gratitude
Fox, Glenn R.; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others. PMID:26483740
Neural correlates of gratitude.
Fox, Glenn R; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others. PMID:26483740
Variable angle correlation spectroscopy
Lee, Y K
1994-05-01
In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with {sup 13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.
2013-08-02
CorAL is a software Library designed to aid in the analysis of femtoscipic data. Femtoscopic data are a class of measured quantities used in heavy-ion collisions to characterize particle emitting source sizes. The most common type of this data is two-particle correleations induced by the Hanbury-Brown/Twiss (HBT) Effect, but can also include correlations induced by final-state interactions between pairs of emitted particles in a heavy-ion collision. Because heavy-ion collisions are complex many particle systems, modelingmore » hydrodynamical models or hybrid techniques. Using the CRAB module, CorAL can turn the output from these models into something that can be directley compared to experimental data. CorAL can also take the raw experimentally measured correlation functions and image them by inverting the Koonin-Pratt equation to extract the space-time emission profile of the particle emitting source. This source function can be further analyzed or directly compared to theoretical calculations.« less
Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde
2012-01-01
Purpose: From independently conducted free-response receiver operating characteristic (FROC) and receiver operating characteristic (ROC) experiments, to study fixed-reader associations between three estimators: the area under the alternative FROC (AFROC) curve computed from FROC data, the area under the ROC curve computed from FROC highest rating data, and the area under the ROC curve computed from confidence-of-disease ratings. Methods: Two hundred mammograms, 100 of which were abnormal, were processed by two image-processing algorithms and interpreted by four radiologists under the FROC paradigm. From the FROC data, inferred-ROC data were derived, using the highest rating assumption. Eighteen months afterwards, the images were interpreted by the same radiologists under the conventional ROC paradigm; conventional-ROC data (in contrast to inferred-ROC data) were obtained. FROC and ROC (inferred, conventional) data were analyzed using the nonparametric area-under-the-curve (AUC), (AFROC and ROC curve, respectively). Pearson correlation was used to quantify the degree of association between the modality-specific AUC indices and standard errors were computed using the bootstrap-after-bootstrap method. The magnitude of the correlations was assessed by comparison with computed Obuchowski-Rockette fixed reader correlations. Results: Average Pearson correlations (with 95% confidence intervals in square brackets) were: Corr(FROC, inferred ROC) = 0.76[0.64, 0.84] > Corr(inferred ROC, conventional ROC) = 0.40[0.18, 0.58] > Corr (FROC, conventional ROC) = 0.32[0.16, 0.46]. Conclusions: Correlation between FROC and inferred-ROC data AUC estimates was high. Correlation between inferred- and conventional-ROC AUC was similar to the correlation between two modalities for a single reader using one estimation method, suggesting that the highest rating assumption might be questionable. PMID:23039631
Zanca, Federica; Hillis, Stephen L.; Claus, Filip; Van Ongeval, Chantal; Celis, Valerie; Provoost, Veerle; Yoon, Hong-Jun; Bosmans, Hilde
2012-10-15
Purpose: From independently conducted free-response receiver operating characteristic (FROC) and receiver operating characteristic (ROC) experiments, to study fixed-reader associations between three estimators: the area under the alternative FROC (AFROC) curve computed from FROC data, the area under the ROC curve computed from FROC highest rating data, and the area under the ROC curve computed from confidence-of-disease ratings. Methods: Two hundred mammograms, 100 of which were abnormal, were processed by two image-processing algorithms and interpreted by four radiologists under the FROC paradigm. From the FROC data, inferred-ROC data were derived, using the highest rating assumption. Eighteen months afterwards, the images were interpreted by the same radiologists under the conventional ROC paradigm; conventional-ROC data (in contrast to inferred-ROC data) were obtained. FROC and ROC (inferred, conventional) data were analyzed using the nonparametric area-under-the-curve (AUC), (AFROC and ROC curve, respectively). Pearson correlation was used to quantify the degree of association between the modality-specific AUC indices and standard errors were computed using the bootstrap-after-bootstrap method. The magnitude of the correlations was assessed by comparison with computed Obuchowski-Rockette fixed reader correlations. Results: Average Pearson correlations (with 95% confidence intervals in square brackets) were: Corr(FROC, inferred ROC) = 0.76[0.64, 0.84] > Corr(inferred ROC, conventional ROC) = 0.40[0.18, 0.58] > Corr (FROC, conventional ROC) = 0.32[0.16, 0.46]. Conclusions: Correlation between FROC and inferred-ROC data AUC estimates was high. Correlation between inferred- and conventional-ROC AUC was similar to the correlation between two modalities for a single reader using one estimation method, suggesting that the highest rating assumption might be questionable.
Correlation Between Blood Lipid Levels and Chronic Pancreatitis
Ni, Qingqiang; Yun, Lin; Xu, Rui; Shang, Dong
2014-01-01
Abstract The incidence of chronic pancreatitis (CP) is increasing, and dyslipidemia severely affects the health of middle-aged and elderly people. We investigated the association between blood lipid levels and CP. The serum lipid metabolic indices of 48 patients with CP (CP group) were summarized retrospectively. The physical examination results of 40 randomly selected healthy individuals were used as the normal control (NC) group. Statistical analyses of the blood lipid data were performed between the 2 groups using the case–control study method. High-density lipoprotein-cholesterol (HDL-c) levels decreased and fasting blood glucose (GLU) levels increased in the CP group compared with those in the NC group (P < 0.01). Pearson correlation analysis results showed that serum amylase (AMY) was positively correlated with low-density lipoprotein-cholesterol (LDL-c; r = 0.414, P < 0.05), and urine AMY (UAMY) was positively correlated with total cholesterol (TC; r = 0.614, P < 0.01) and LDL-c (r = 0.678, P < 0.01). A binary logistic regression analysis showed that GLU (odds ratio [OR], 5.052; P < 0.01) and TC (OR, 1.074; P < 0.01) may be risk factors for CP, whereas HDL-c may be a CP protective factor (OR, 0.833; P < 0.01). The HDL-c levels decreased and GLU levels increased in the CP group compared with those in the NC group; AMY was positively correlated with LDL-c and UAMY was positively correlated with TC and LDL-c; GLU and TC may be risk factors for CP; and HDL-c may be a CP protective factor. This may be the first time that such results have been reported. These findings will contribute to primary prevention and control of CP progression. PMID:25526493
Peyman, Mohammadreza; Tajunisah, Iqbal; Loo, Angela; Chuah, Khai Choon; Subrayan, Visvaraja
2012-01-01
To correlate Heidelberg Retina Tomograph (HRT) derived macular edema (DME) index with severity of diabetic retinopathy and systemic factors. A total of 300 diabetic patients were recruited for the study for each of them a value for the macular edema index was obtained using the HRT II. Patients' age, gender, duration and type of diabetes mellitus, latest HbA1c result and presence or absence of co-morbid factors (hypertension, ischemic heart disease, nephropathy) were recorded together with the stage of diabetic retinopathy. These were correlated with DME. Out of 300 patients, HRT defined macula edema was seen in 68 patients (22.6%). There is a wider and higher range (95% percentile) of macula edema index in the severe non proliferative diabetic retinopathy (NPDR) group. Independent samples t test showed significant difference between the severe NPDR group and no DR group (p<0.001), mild NPDR group (p<0.05) and moderate NPDR group (p<0.05). A higher macula edema index was also found to have a low degree of correlation with more advanced stages of retinopathy (r=0.310; p<0.001). Also nephropathy showed a strong and significant correlation with DME. Hypertension had moderately significant correlation with DME. This study found no correlation between ischemic heart disease and DME. HRT derived scanning laser edema index is a reliable objective tool to evaluate diabetic retinopathy and systemic risk factors. PMID:22520399
Gupta, Mohit; Divyashree, R; Abhilash, PR; A Bijle, Mohammed Nadeem; Murali, KV
2013-01-01
Introduction: Chronological age, dental development, height and weight measurements, sexual maturation characteristics and skeletal age are some biological indicators that have been used to identify time of growth. Many researchers have agreed that skeletal maturity is closely related to the craniofacial growth, and bones of hand and wrist are reliable parameters in assessing it. The complete hand and wrist radiograph involves 30 bones and assessment of these bones is one elaborate task. The present study is therefore, undertaken to assess the correlation between the chronological age, dental age and skeletal ages among different types of twins. Materials and Methods: The study consisted of 60 subjects (30 twins) aged 8 to 16 years, divided into group of 10 monozygotic, 10 dizygotic and 10 mixed sex twins. The sample was selected from Twin Survey- 2008 conducted by Department of Orthodontics and Dentofacial Orthopaedics, Sree Balaji Dental College and Hospital, Chennai. Their zygosity was determined by sex, blood groups and by the parent. The chronological age was measured by the date of birth given by the parents. Panoramic and hand wrist x-rays were taken. Dental age was assessed by Demerjian et al method and skeletal age by Greulich and Pyle method. The correlation among twins in dental and skeletal ages with the chronological age was assessed using Correlation Coefficient and Student's't' Test. Results: The obtained data was fed into the computer and statistical analysis was done for the same using the SPSS version 10.0. Statistical significance was tested at P<0.05 level. Mean and Standard Deviation, Correlation Coefficient, Student's't' Test statistical methods were employed. The result showed highly significant 'p' value as <0.001 in all the correlations except for mixed pairs. Descriptive statistics in most of the areas demonstrated a non-significant result between zygosity groups. Conclusion: There is a correlation existing between the individual
Bootstrapped Deattenuated Correlation: Nonnormal Distributions
ERIC Educational Resources Information Center
Padilla, Miguel A.; Veprinsky, Anna
2014-01-01
Correlation attenuation due to measurement error and a corresponding correction, the deattenuated correlation, have been known for over a century. Nevertheless, the deattenuated correlation remains underutilized. A few studies in recent years have investigated factors affecting the deattenuated correlation, and a couple of them provide alternative…
Holden, Kisha B.; Bradford, L. Dianne; Hall, Stephanie P.; Belton, Allyson S.
2014-01-01
The purpose of this cross-sectional pilot study was to determine the prevalence and correlates of depressive symptoms and resiliency among 290 African American women (AAW) in a community-based primary health care center. Descriptive statistics, Pearson product-moment correlation, and logistic regression analyses were conducted. Findings indicate that depressive symptoms are experienced by 49% of the participants, while 10% indicated a history of suicidal ideation. Participants had moderately high resiliency scores that had a statistically significant inverse relationship with depressive symptoms. This suggests that resiliency is potentially a protective factor for depressive symptoms. Depressive symptoms were positively correlated with 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. PMID:24241263
Strongly correlated Bose gases
NASA Astrophysics Data System (ADS)
Chevy, F.; Salomon, C.
2016-10-01
The strongly interacting Bose gas is one of the most fundamental paradigms of quantum many-body physics and the subject of many experimental and theoretical investigations. We review recent progress on strongly correlated Bose gases, starting with a description of beyond mean-field corrections. We show that the Efimov effect leads to non universal phenomena and to a metastability of the low temperature Bose gas through three-body recombination to deeply bound molecular states. We outline differences and similarities with ultracold Fermi gases, discuss recent experiments on the unitary Bose gas, and finally present a few perspectives for future research.
Digital Image Correlation Engine
Turner, Dan; Crozier, Paul; Reu, Phil
2015-10-06
DICe is an open source digital image correlation (DIC) tool intended for use as a module in an external application or as a standalone analysis code. It's primary capability is computing full field displacements and strains from sequences of digital These images are typically of a material sample undergoing a materials characterization experiment, but DICe is also useful for other applications (for example, trajectory tracking). DICe is machine portable (Windows, Linux and Mac) and can be effectively deployed on a high performance computing platform. Capabilities from DICe can be invoked through a library interface, via source code integration of DICe classes or through a graphical user interface.
Two-Way Gene Interaction From Microarray Data Based on Correlation Methods
Alavi Majd, Hamid; Talebi, Atefeh; Gilany, Kambiz; Khayyer, Nasibeh
2016-01-01
Background Gene networks have generated a massive explosion in the development of high-throughput techniques for monitoring various aspects of gene activity. Networks offer a natural way to model interactions between genes, and extracting gene network information from high-throughput genomic data is an important and difficult task. Objectives The purpose of this study is to construct a two-way gene network based on parametric and nonparametric correlation coefficients. The first step in constructing a Gene Co-expression Network is to score all pairs of gene vectors. The second step is to select a score threshold and connect all gene pairs whose scores exceed this value. Materials and Methods In the foundation-application study, we constructed two-way gene networks using nonparametric methods, such as Spearman’s rank correlation coefficient and Blomqvist’s measure, and compared them with Pearson’s correlation coefficient. We surveyed six genes of venous thrombosis disease, made a matrix entry representing the score for the corresponding gene pair, and obtained two-way interactions using Pearson’s correlation, Spearman’s rank correlation, and Blomqvist’s coefficient. Finally, these methods were compared with Cytoscape, based on BIND, and Gene Ontology, based on molecular function visual methods; R software version 3.2 and Bioconductor were used to perform these methods. Results Based on the Pearson and Spearman correlations, the results were the same and were confirmed by Cytoscape and GO visual methods; however, Blomqvist’s coefficient was not confirmed by visual methods. Conclusions Some results of the correlation coefficients are not the same with visualization. The reason may be due to the small number of data.
Two-Way Gene Interaction From Microarray Data Based on Correlation Methods
Alavi Majd, Hamid; Talebi, Atefeh; Gilany, Kambiz; Khayyer, Nasibeh
2016-01-01
Background Gene networks have generated a massive explosion in the development of high-throughput techniques for monitoring various aspects of gene activity. Networks offer a natural way to model interactions between genes, and extracting gene network information from high-throughput genomic data is an important and difficult task. Objectives The purpose of this study is to construct a two-way gene network based on parametric and nonparametric correlation coefficients. The first step in constructing a Gene Co-expression Network is to score all pairs of gene vectors. The second step is to select a score threshold and connect all gene pairs whose scores exceed this value. Materials and Methods In the foundation-application study, we constructed two-way gene networks using nonparametric methods, such as Spearman’s rank correlation coefficient and Blomqvist’s measure, and compared them with Pearson’s correlation coefficient. We surveyed six genes of venous thrombosis disease, made a matrix entry representing the score for the corresponding gene pair, and obtained two-way interactions using Pearson’s correlation, Spearman’s rank correlation, and Blomqvist’s coefficient. Finally, these methods were compared with Cytoscape, based on BIND, and Gene Ontology, based on molecular function visual methods; R software version 3.2 and Bioconductor were used to perform these methods. Results Based on the Pearson and Spearman correlations, the results were the same and were confirmed by Cytoscape and GO visual methods; however, Blomqvist’s coefficient was not confirmed by visual methods. Conclusions Some results of the correlation coefficients are not the same with visualization. The reason may be due to the small number of data. PMID:27621916
Loturco, I; Barbosa, A C; Nocentini, R K; Pereira, L A; Kobal, R; Kitamura, K; Abad, C C C; Figueiredo, P; Nakamura, F Y
2016-03-01
Swimmers are often tested on both dry-land and in swimming exercises. The aim of this study was to test the relationships between dry-land, tethered force-time curve parameters and swimming performances in distances up to 200 m. 10 young male high-level swimmers were assessed using the maximal isometric bench-press and quarter-squat, mean propulsive power in jump-squat, squat and countermovement jumps (dry-land assessments), peak force, average force, rate of force development (RFD) and impulse (tethered swimming) and swimming times. Pearson product-moment correlations were calculated among the variables. Peak force and average force were very largely correlated with the 50- and 100-m swimming performances (r=- 0.82 and -0.74, respectively). Average force was very-largely/largely correlated with the 50- and 100-m performances (r=- 0.85 and -0.67, respectively). RFD and impulse were very-largely correlated with the 50-m time (r=- 0.72 and -0.76, respectively). Tethered swimming parameters were largely correlated (r=0.65 to 0.72) with mean propulsive power in jump-squat, squat-jump and countermovement jumps. Finally, mean propulsive power in jump-squat was largely correlated (r=- 0.70) with 50-m performance. Due to the significant correlations between dry-land assessments and tethered/actual swimming, coaches are encouraged to implement strategies able to increase leg power in sprint swimmers.
Vibrational Echo Correlation Spectroscopy
NASA Astrophysics Data System (ADS)
Asbury, John B.; Steinel, Tobias; Fayer, M. D.
Multidimensional vibrational echo correlation spectroscopy with full phase resolution is used to measure hydrogen bond dynamics in water and methanol. The OD hydroxyl stretches of methanol-OD oligomers in CCl4 and HOD inH2O are studied using the shortest mid-IR pulses (< 45 fs, < 4 cycles of light) produced to date. The pulses have sufficient spectral bandwidth to span the very broad (> 400 cm-1) spectrum of the 0-1 and 1-2 vibrational transitions. Hydrogen bond population dynamics are extricated with exceptional detail in MeOD oligomers because the different hydrogen-bonded species are spectrally distinct. The experimental results along with detailed calculations indicate the strongest hydrogen bonds are selectively broken through a non-equilibrium relaxation pathway following vibrational relaxation of the hydroxyl stretch. Following hydrogen bond breaking, the broken MeOD oligomers retain a detailed structural memory of the prior intact hydrogen bond network. The correlation spectra are also a sensitive probe of the structural fluctuations in water and provide a stringent test of water models that are widely used in simulations of aqueous systems. The analysis of the 2D band shapes demonstrates that different hydrogen-bonded species are subject to distinct (wavelength-dependent) ultrafast (˜ 100 fs) local fluctuations and essentially identical slower (0.4 ps and ˜ 2 ps) structural rearrangements. Observation of wavelength-dependent dynamics demonstrates that standard theoretical approaches assuming Gaussian fluctuations cannot adequately describe water dynamics.
CONDITIONAL DISTANCE CORRELATION
Wang, Xueqin; Pan, Wenliang; Hu, Wenhao; Tian, Yuan; Zhang, Heping
2015-01-01
Statistical inference on conditional dependence is essential in many fields including genetic association studies and graphical models. The classic measures focus on linear conditional correlations, and are incapable of characterizing non-linear conditional relationship including non-monotonic relationship. To overcome this limitation, we introduces a nonparametric measure of conditional dependence for multivariate random variables with arbitrary dimensions. Our measure possesses the necessary and intuitive properties as a correlation index. Briefly, it is zero almost surely if and only if two multivariate random variables are conditionally independent given a third random variable. More importantly, the sample version of this measure can be expressed elegantly as the root of a V or U-process with random kernels and has desirable theoretical properties. Based on the sample version, we propose a test for conditional independence, which is proven to be more powerful than some recently developed tests through our numerical simulations. The advantage of our test is even greater when the relationship between the multivariate random variables given the third random variable cannot be expressed in a linear or monotonic function of one random variable versus the other. We also show that the sample measure is consistent and weakly convergent, and the test statistic is asymptotically normal. By applying our test in a real data analysis, we are able to identify two conditionally associated gene expressions, which otherwise cannot be revealed. Thus, our measure of conditional dependence is not only an ideal concept, but also has important practical utility. PMID:26877569
Evaluation of clinical and laboratory correlates of sickle leg ulcers.
Madu, Anazoeze Jude; Ubesie, Agozie; Madu, Kenechi Anthony; Okwor, Bismarck; Anigbo, Chukwudi
2013-01-01
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.
PREFACE: Correlated Electrons (Japan)
NASA Astrophysics Data System (ADS)
Miyake, Kazumasa
2007-03-01
This issue of Journal of Physics: Condensed Matter is dedicated to results in the field of strongly correlated electron systems under multiple-environment. The physics of strongly correlated electron systems (SCES) has attracted much attention since the discovery of superconductivity in CeCu_2 Si_2 by Steglich and his co-workers a quater-century ago. Its interest has been intensified by the discovery of high-Tc superconductivity in a series of cuprates with layered perovskite structure which are still under active debate. The present issue of Journal of Physics: Condensed Matter present some aspects of SCES physics on the basis of activities of a late project "Centre-Of-Excellence" supported by MEXT (Ministry of Education, Sports, Science, Culture and Technology of the Japanese Government). This project has been performed by a condensed matter physics group in the faculties of science and engineering science of Osaka University. Although this project also covers correlated phenomena in optics and nano-scale systems, we focus here on the issues of SCES related to superconductivity, mainly unconventional. The present issue covers the discussions on a new mechanism of superconductivity with electronic origin (critical valence fluctuation mechanism), interplay and unification of magnetism and superconductivity in SCES based on a systematic study of NQR under pressure, varieties of Fermi surface of Ce- and U-based SCES probed by the de Haas-van Alphen effect, electronic states probed by a bulk sensitive photoemission spectroscopy with soft X-ray, pressure induced superconductivity of heavy electron materials, pressure dependence of superconducting transition temperature based on a first-principle calculation, and new superconductors under very high-pressure. Some papers offer readers' reviews of the relevant fields and/or include new developments of this intriguing research field of SCES. Altogether, the papers within this issue outline some aspects of electronic states
Sundaralingam, M.; Westhof, E.
1980-10-01
The furanose ring of nucleic acids plays a key role in detrmining the conformations of nucleic acids because it shares a common bond C3'-C4'(psi') with the sugar-phosphate backbone. This structural feature enables the transmission of conformational changes between the side-chain base and the backbone through conformational correlations between the base and sugar. Thermally-induced local fluctuations of P can be transmitted along the backbone through psi', particularly when the sugar is in the C2'-endo domain. The sugar pucker-dependent flexibility of DNA is further exemplified by studies that have shown that due to steric interactions, absence of the 2'-OH group in deoxyribose tends to increase the conformational flexibility about the internucleotide phosphodiester (..omega.., ..omega..') especially when the sugar assumes the C2'-endo pucker.
Neural correlates of frustration.
Abler, Birgit; Walter, Henrik; Erk, Susanne
2005-05-12
Psychological considerations suggest that the omission of rewards in humans comprises two effects: first, an allocentric effect triggering learning and behavioural changes potentially processed by dopaminergic neurons according to the prediction error theory; second, an egocentric effect representing the individual's emotional reaction, commonly called frustration. We investigated this second effect in the context of omission of monetary reward with functional magnetic resonance imaging. As expected, the contrast omission relative to receipt of reward led to a decrease in ventral striatal activation consistent with prediction error theory. Increased activation for this contrast was found in areas previously related to emotional pain: the right anterior insula and the right ventral prefrontal cortex. We interpreted this as a neural correlate of the egocentric effect.
Digital Image Correlation Engine
2015-10-06
DICe is an open source digital image correlation (DIC) tool intended for use as a module in an external application or as a standalone analysis code. It's primary capability is computing full field displacements and strains from sequences of digital These images are typically of a material sample undergoing a materials characterization experiment, but DICe is also useful for other applications (for example, trajectory tracking). DICe is machine portable (Windows, Linux and Mac) and canmore » be effectively deployed on a high performance computing platform. Capabilities from DICe can be invoked through a library interface, via source code integration of DICe classes or through a graphical user interface.« less
Frost, T; Stimpson, D V; Maughan, M R
1978-05-01
Trust has been variously defined by behavioral scientists and not very thoroughly investigated. In this study trust was defined as an expectancy held by an individual that the behavior of another person or a group would be altruistic and personally beneficial. An attempt was made, using this conceptual definition, to identify some personality and behavioral correlates of trust. Seven interpersonal relations groups with approximately 10 male and female undergraduates per group were studied with use of the Janis and Field self-esteem inventory, Schutz's FIRO-B scale, and the Rotter internal-external scale. It was discovered that a trusted person is one who is highly influential, has an internal locus of control, a low need to control others, high self-esteem, and is open to being influenced by others.
EEG correlates of submovements.
Dipietro, L; Poizner, H; Krebs, H I
2011-01-01
Numerous studies on motor control in humans and primates have suggested that the Central Nervous System (CNS) generates and controls continuous movement via discrete, elementary units of movement or submovements. While most studies are based on analysis of kinematic data, investigations of neural correlates have been lacking. To fill this gap we recorded and analyzed kinematic and high-density electroencephalographic (64-channel EEG) data from three right-handed normal adults during a reaching task that required online movement corrections. Each kinematic submovement was accompanied by stereotyped scalp maps. Furthermore, the peaks of event-related potentials (ERP) recorded at electrode C1 (over contralateral motor cortex) were time-locked to kinematic submovement peaks. These results provide further evidence for the hypothesis that the CNS generates and controls continuous movement via discrete submovements. Applications include design of quantitative outcome metrics for motor disorders of neurological origin such as stroke and Parkinson's disease. PMID:22256056
Corwin, W.R.
1995-10-01
This task has been established with the explicit purpose of ensuring the continued availability of the pedigreed and extremely well-characterized material now required for inclusion in all additional and future surveillance capsules in commercial light-water reactors. During this reporting period, concrete was poured and pallets storage racks were installed to provide adequate room for the storage of the correlation monitor material being transferred from its location at the Y-12 Plant to its archival storage location at ORNL. The racks came from surplus material storage at ORNL and hence were obtained at no cost to the HSSI Program. Inquiries into cost-effective means of sheltering the blocks of correlation monitor materials from further weather-related deteriorization were initiated. The most likely approach would be to procure a turn-key sheet metal building installed over the storage racks by an outside contractor to minimize costs. Most of the material has now been transferred from Y-12 to the ORNL storage area. It has been repositioned on new storage pallets and placed into the storage racks, An update of the detailed material inventory was initiated to ascertain the revised location of all blocks. Pieces of HSST plate O3 were distributed to participants in the ASTM cross-comparison exercise on subsize specimen testing technology. The use of the HSST O3 will provide for data from the many varieties of tests to be performed to be compared with the standardized data previously developed. The testing techniques will focus on ways to measure transition temperature and fracture toughness.
``A Desideratum in Spectrology'': an Editor's Lament in the Great Correlation Era
NASA Astrophysics Data System (ADS)
DeVorkin, David
2012-09-01
Of all the known observable characteristics of the stars in the late 19th Century, classification by the appearance of their spectra was by far the most problematic. In 1904, Edwin Frost lamented that some 23 distinct classification systems had been created, yet none were universally accepted. In 1908, the applied mathematician Karl Pearson and a student evaluated correlations between spectra and other characteristics of the stars, hoping to ``look upon the stellar universe as an orderly whole ... by which we pass from chaos to an organised and locally differentiated cosmos.'' None of the major spectral systems, however, allowed them to draw any conclusions, other than state a high correlation with color. Yet, by 1917, astronomers were making correlations, and applying them, to make some pretty strong statements about the nature and history of the sidereal system as well as the lives of the stars. One of the strongest was the technique of spectroscopic parallaxes. But even its discoverer, Walter Sydney Adams, worried about what it all meant. Writing to Eddington in 1917, Adams wished that ``we had more physical knowledge regarding the interpretations of stellar spectra.'' And as E. A. Milne observed some years later, in retrospect, ``[t]here was a gap in the logical argument.'' My talk will address some historiographical issues arising from this phase in the development of modern astrophysics that hopefully will illuminate why the gap was closed in the way it was closed, and the effect it had on the continuing process of spectral classification.
Source apportionment advances using polar plots of bivariate correlation and regression statistics
NASA Astrophysics Data System (ADS)
Grange, Stuart K.; Lewis, Alastair C.; Carslaw, David C.
2016-11-01
This paper outlines the development of enhanced bivariate polar plots that allow the concentrations of two pollutants to be compared using pair-wise statistics for exploring the sources of atmospheric pollutants. The new method combines bivariate polar plots, which provide source characteristic information, with pair-wise statistics that provide information on how two pollutants are related to one another. The pair-wise statistics implemented include weighted Pearson correlation and slope from two linear regression methods. The development uses a Gaussian kernel to locally weight the statistical calculations on a wind speed-direction surface together with variable-scaling. Example applications of the enhanced polar plots are presented by using routine air quality data for two monitoring sites in London, United Kingdom for a single year (2013). The London examples demonstrate that the combination of bivariate polar plots, correlation, and regression techniques can offer considerable insight into air pollution source characteristics, which would be missed if only scatter plots and mean polar plots were used for analysis. Specifically, using correlation and slopes as pair-wise statistics, long-range transport processes were isolated and black carbon (BC) contributions to PM2.5 for a kerbside monitoring location were quantified. Wider applications and future advancements are also discussed.
Handgrip explosive force is correlated with mobility in the elderly women.
Borges, Lucio Santos; Fernandes, Marcos Henrique; Schettino, Ludmila; DA Silva Coqueiro, Raildo; Pereira, Rafael
2015-01-01
The analysis of explosive force, through rate of force development (RFD) and contractile impulse (CI), from handgrip strength data seems to be useful and promising information to study the aging of musculoskeletal system and health status. We aimed to test the hypothesis that, in elderly women, the handgrip explosive force could be better associated to the functional mobility than maximum handgrip strength. Handgrip strength and the performance of Timed Up & Go Test (TUG) were measured from sixty-five community-dwelling healthy elderly women. The average slope of the moment-time curve (Δ moment/Δ time) over the time interval of 0-200 ms relative to the onset of contraction was calculated to provide the RFD and CI. The highest strength achieved during the isometric contraction was used as maximum handgrip strength. Pearson correlations were used to assess the strength of the relationship between the handgrip strength parameters (Maximum strength and explosive force from 0-200 ms) and TUG test performance from older women. The correlation analysis showed that the TUG test performance was inversely correlated to the handgrip strength parameters, with better relationship with explosive force parameters. The handgrip explosive force seems to be a promising predictor of functional mobility of elderly women, since it showed a better relationship with functional mobility than maximum handgrip strength.
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
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.
Rao, Guodong; Sui, Jinkai
2016-01-01
ABSTRACT The content of walnut metabolites is related to its nutritive value and physiological characteristics, however, comprehensive information concerning the metabolome of walnut kernels is limited. In this study we analyzed the metabolites of walnut kernels at five developmental stages from filling to ripening using GC-MS-based untargeted metabolomics; of a total 252 peaks identified, 85 metabolites were positively identified. Further statistical analysis revealed that these 85 metabolites covered different types of metabolism pathways. PCA scores revealed that the metabolic compositions of the embryo are different at each stage, while the metabolic composition of the endotesta could not be significantly separated into distinct groups. Additionally, 7225 metabolite-metabolite correlations were detected in walnut kernel by a Pearson correlation coefficient approach; during screening of the calculated correlations, 463 and 1047 were determined to be significant with r2≥0.49 and had a false discovery rate (FDR) ≤0.05 in endotesta and embryo, respectively. This work provides the first comprehensive metabolomic study of walnut kernels and reveals that most of the carbohydrate and protein-derived carbon was transferred into other compounds, such as fatty acids, during the maturation of walnuts, which may potentially provide the basis for further studies on walnut kernel metabolism. PMID:27215321
Rao, Guodong; Sui, Jinkai; Zhang, Jianguo
2016-06-15
The content of walnut metabolites is related to its nutritive value and physiological characteristics, however, comprehensive information concerning the metabolome of walnut kernels is limited. In this study we analyzed the metabolites of walnut kernels at five developmental stages from filling to ripening using GC-MS-based untargeted metabolomics; of a total 252 peaks identified, 85 metabolites were positively identified. Further statistical analysis revealed that these 85 metabolites covered different types of metabolism pathways. PCA scores revealed that the metabolic compositions of the embryo are different at each stage, while the metabolic composition of the endotesta could not be significantly separated into distinct groups. Additionally, 7225 metabolite-metabolite correlations were detected in walnut kernel by a Pearson correlation coefficient approach; during screening of the calculated correlations, 463 and 1047 were determined to be significant with r(2)≥0.49 and had a false discovery rate (FDR) ≤0.05 in endotesta and embryo, respectively. This work provides the first comprehensive metabolomic study of walnut kernels and reveals that most of the carbohydrate and protein-derived carbon was transferred into other compounds, such as fatty acids, during the maturation of walnuts, which may potentially provide the basis for further studies on walnut kernel metabolism.
NASA Astrophysics Data System (ADS)
da Silva, Roberto; Lamb, Luis C.; Barbosa, Marcia C.
2016-09-01
We analyze the scores obtained by students who have taken the ENEM examination, The Brazilian High School National Examination which is used in the admission process at Brazilian universities. The average high schools scores from different disciplines are compared through the Pearson correlation coefficient. The results show a very large correlation between the performance in the different school subjects. Even though the students' scores in the ENEM form a Gaussian due to the standardization, we show that the high schools' scores form a bimodal distribution that cannot be used to evaluate and compare students performance over time. We also show that this high schools distribution reflects the correlation between school performance and the economic level (based on the average family income) of the students. The ENEM scores are compared with a Brazilian non standardized exam, the entrance examination from the Universidade Federal do Rio Grande do Sul. The analysis of the performance of the same individuals in both tests shows that the two tests not only select different abilities, but also lead to the admission of different sets of individuals. Our results indicate that standardized tests might be an interesting tool to compare performance of individuals over the years, but not of institutions.
Magnitude correlations in global seismicity
Sarlis, N. V.
2011-08-15
By employing natural time analysis, we analyze the worldwide seismicity and study the existence of correlations between earthquake magnitudes. We find that global seismicity exhibits nontrivial magnitude correlations for earthquake magnitudes greater than M{sub w}6.5.
Correlation between BOLD-MRI and HIF expression level in renal carcinoma
Li, Dong; Wang, Xingming; Wang, Shuai; Cheng, Jie
2015-01-01
Occupying about 2%~3% of all malignant tumors, renal carcinoma is the most common primary cancer in kidney. The oxidative level of tumor cells is of vital role for optimizing treatment plan, evaluating efficacy and predicting prognosis. This study thus investigated the R2* value in mouse renal carcinoma model and the correlation between tumor hypoxia and expression level of hypoxia inducible factor-1 (HIF-1). A total of 20 BALB/C nude mice (4~6 weeks old) were inoculated with human ACHN renal carcinoma cells to generate renal cancer model. After the tumor diameter reached 0.5 cm, all animals were examined by BOLD-MRI, both under normal inhalation (R2a*) and carbogen treatment (R2b*). The alternation of R2* values (ΔR2*=R2a* - R2b*) was calculated. Mice were then sacrificed for Immunohistochemical (IHC) staining targeting HIF-1α and HIF-2α. The positive score of HIF was then analyzed for its correlation with R2* value. In 18 mice finished both experiments, Pearson correlation analysis revealed significant negative correlation between R2a* and ΔR2* (r=-0.48, P<0.05) and positive relationship between ΔR2* and HIF-2α (r=0.38, P<0.05). HIF-1α level, however, did not correlated with tumor R* values. The positive correlation between ΔR2* and HIF-2α, but not HIF-1α, suggested potential role of combined BOLD-MRI technique and HIF-1α staining in clinical diagnosis of renal carcinoma. HIF-2α may work as biological marker for renal cancer. PMID:26722605
A correlation between hard gamma-ray sources and cosmic voids along the line of sight
Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.
2014-11-25
We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV flux and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.
A correlation between hard gamma-ray sources and cosmic voids along the line of sight
Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.
2014-11-25
We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV fluxmore » and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.« less
Correlation Between Dental Arch Width and Sagittal Dento-Skeletal Morphology in Untreated Adults
Shahroudi, Atefe Saffar; Etezadi, Tahura
2013-01-01
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
NASA Astrophysics Data System (ADS)
Takeuchi, Tsutomu T.
2010-08-01
We provide an analytic method to construct a bivariate distribution function (DF) with given marginal distributions and correlation coefficient. We introduce a convenient mathematical tool, called a copula, to connect two DFs with any prescribed dependence structure. If the correlation of two variables is weak (Pearson's correlation coefficient |ρ| < 1/3), the Farlie-Gumbel-Morgenstern (FGM) copula provides an intuitive and natural way to construct such a bivariate DF. When the linear correlation is stronger, the FGM copula cannot work anymore. In this case, we propose using a Gaussian copula, which connects two given marginals and is directly related to the linear correlation coefficient between two variables. Using the copulas, we construct the bivariate luminosity function (BLF) and discuss its statistical properties. We focus especially on the far-infrared-far-ulatraviolet (FUV-FIR) BLF, since these two wavelength regions are related to star-formation (SF) activity. Though both the FUV and FIR are related to SF activity, the univariate LFs have a very different functional form: the former is well described by the Schechter function whilst the latter has a much more extended power-law-like luminous end. We construct the FUV-FIR BLFs using the FGM and Gaussian copulas with different strengths of correlation, and examine their statistical properties. We then discuss some further possible applications of the BLF: the problem of a multiband flux-limited sample selection, the construction of the star-formation rate (SFR) function, and the construction of the stellar mass of galaxies (M*)-specific SFR (SFR/M*) relation. The copulas turn out to be a very useful tool to investigate all these issues, especially for including complicated selection effects.
Correlation Between Vision and Cognitive Function in the Elderly: A Cross-Sectional Study.
Spierer, Oriel; Fischer, Naomi; Barak, Adiel; Belkin, Michael
2016-01-01
The correlation between vision and cognition is not fully understood. Visual impairment in the elderly has been associated with impaired cognitive function, dementia, and Alzheimer disease. The aim was to study the correlation between near visual acuity (VA), refraction, and cognitive state in an elderly population.Subjects ≥75 years were enrolled in this cross-sectional study. Refraction and near VA was tested. Cognitive function was evaluated with a version of the mini-mental state examination for the visually impaired (MMSE-blind). The eye with better VA and no cataract or refractive surgery was analyzed.One-hundred ninety subjects (81.6 ± 5.1 years, 69.5% female) were included. Good VA (≤J3) was associated with high MMSE-blind (>17) (OR = 3.18, 95% CI = 1.57-6.43, P = 0.001). This remained significant adjusting for sex, age, and years of education. Wearing reading glasses correlated significantly with high MMSE-blind after adjustment for sex and age (OR = 2.14, 95% CI = 1.16-3.97, P = 0.016), but reached borderline significance after adjustment for education. There was a trend toward correlation between myopia and better MMSE-blind (r = -0.123, P = 0.09, Pearson correlation).Good VA and wearing glasses seem to correlate with better cognitive function. Reading glasses can serve as a protective factor against cognitive deterioration associated with sensory (visual) deprivation in old age. The association between myopia and cognition requires further investigation.
NASA Astrophysics Data System (ADS)
Curme, Chester
Technological advances have provided scientists with large high-dimensional datasets that describe the behaviors of complex systems: from the statistics of energy levels in complex quantum systems, to the time-dependent transcription of genes, to price fluctuations among assets in a financial market. In this environment, where it may be difficult to infer the joint distribution of the data, network science has flourished as a way to gain insight into the structure and organization of such systems by focusing on pairwise interactions. This work focuses on a particular setting, in which a system is described by multivariate time series data. We consider time-lagged correlations among elements in this system, in such a way that the measured interactions among elements are asymmetric. Finally, we allow these interactions to be characteristically weak, so that statistical uncertainties may be important to consider when inferring the structure of the system. We introduce a methodology for constructing statistically validated networks to describe such a system, extend the methodology to accommodate interactions with a periodic component, and show how consideration of bipartite community structures in these networks can aid in the construction of robust statistical models. An example of such a system is a financial market, in which high frequency returns data may be used to describe contagion, or the spreading of shocks in price among assets. These data provide the experimental testing ground for our methodology. We study NYSE data from both the present day and one decade ago, examine the time scales over which the validated lagged correlation networks exist, and relate differences in the topological properties of the networks to an increasing economic efficiency. We uncover daily periodicities in the validated interactions, and relate our findings to explanations of the Epps Effect, an empirical phenomenon of financial time series. We also study bipartite community
The 512-channel correlator controller
NASA Technical Reports Server (NTRS)
Brokl, S. S.
1976-01-01
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.
Liquid-Crystal Optical Correlator
NASA Technical Reports Server (NTRS)
Liu, Hua-Kuang
1989-01-01
Optical correlator uses commercially-available liquid-crystal television (LCTV) screen as spatial light modulator. Correlations with this device done at video frame rates, making such operations as bar-code recognition possible at reasonable cost. With further development, such correlator useful in automation, robotic vision, and optical image processing.
Portone, Carissa R; Hapner, Edie R; McGregor, Laura; Otto, Kristen; Johns, Michael M
2007-11-01
The purpose of this study was to investigate the correlation between the Voice Handicap Index (VHI) and the Voice-Related Quality of Life Measure (V-RQOL), and to test conversion of scores between the two instruments. Understanding the relationship between instruments will facilitate comparison of voice outcome studies using different measures. A retrospective medical chart review of 140 consecutive patients with a chief complaint related to their voice presenting for speech pathology voice evaluation following laryngology evaluation and diagnosis was adopted. Each patient who filled out the VHI and V-RQOL within a 2-week period with no intervening treatment was included in the study. Correlation analysis for total scores was performed for the patients meeting inclusion criteria (n=132). Correlations were also performed as a function of diagnosis. Calculated VHI score based on measured V-RQOL score was compared to measured VHI score. Pearson correlation between scores on the VHI and V-RQOL was -0.82. There was no significant difference between the mean measured and mean calculated VHI scores. For individual scores, however, regression analysis did reveal a significant difference between calculated and measured VHI. The VHI and V-RQOL are highly correlated; however, this study suggests that the two instruments are not interchangeable for individuals.
Kumar, Dharmendra; Ahmed, Syed Moied; Ali, Shahna; Ray, Utpal; Varshney, Ankur; Doley, Kashmiri
2015-01-01
Background: Central venous pressure (CVP) assesses the volume status of patients. However, this technique is not without complications. We, therefore, measured peripheral venous pressure (PVP) to see whether it can replace CVP. Aims: To evaluate the correlation and agreement between CVP and PVP after passive leg raise (PLR) in critically ill patients on mechanical ventilation. Setting and Design: Prospective observational study in Intensive Care Unit. Methods: Fifty critically ill patients on mechanical ventilation were included in the study. CVP and PVP measurements were taken using a water column manometer. Measurements were taken in the supine position and subsequently after a PLR of 45°. Statistical Analysis: Pearson's correlation and Bland–Altman's analysis. Results: This study showed a fair correlation between CVP and PVP after a PLR of 45° (correlation coefficient, r = 0.479; P = 0.0004) when the CVP was <10 cmH2O. However, the correlation was good when the CVP was >10 cmH2O. Bland–Altman analysis showed 95% limits of agreement to be −2.912–9.472. Conclusion: PVP can replace CVP for guiding fluid therapy in critically ill patients. PMID:26730115
Chikamatsu, Kinuyo; Aono, Akio; Kato, Tomoko; Takaki, Akiko; Yamada, Hiroyuki; Sasaki, Yuka; Izumi, Kiyohiko; Yi, Lina; Mitarai, Satoshi
2016-01-01
We investigated the correlation between the cycle threshold (Ct) value of the COBAS(®) TaqMan(®) MTB (TaqMan MTB), the mycobacterial smear positivity grade, and the time to detection (TTD) in the Mycobacteria Growth Indicator Tube (MGIT) for quantification of Mycobacterium tuberculosis (MTB). For 57 sputum samples, significant correlations were observed between the Ct value, the smear positivity grade, and the MGIT TTD (Spearman's rank correlation coefficient: r(s) = -0.940, P < 0.001 and Pearson's correlation coefficient: r(p) = 0.737, P < 0.001). In addition, a correlation was observed between the number of bacteria estimated based on the smear positivity grade and the number of MTB bacilli calculated by the Ct value (r(s) = 0.930, P < 0.001). This study has demonstrated the possible estimation of the smear positivity grade and MGIT TTD using the Ct value of TaqMan MTB, which is based on a real-time PCR system, for diagnostic samples.
Zhang, Yanyan; Wang, Bei; Zhou, Cunshan; Atungulu, Griffiths G; Xu, Kangkang; Ma, Haile; Ye, Xiaofei; Abdualrahman, Mohammed A Y
2016-07-01
The effects of alternate dual-frequency ultrasound (ADFU) pretreatment on the degree of hydrolysis (DH) of wheat gluten (WG) and angiotensin I-converting enzyme (ACE) inhibitory activity were investigated in this research. The surface topography, nano-mechanics and secondary structure of WG were also determined using atomic force microscope (AFM) and circular dichroism (CD). The correlations of ACE inhibitory activity and DH with surface topography, nano-mechanics and secondary structure of WG were determined using Pearson's correlation analysis. The results showed that with an increase in either pretreatment duration or power, the ACE inhibitory activity of the hydrolysate also increases, reaching maximum at 10 min and 150 W/L, respectively, and then decreases thereafter. Similarly, AFM analysis showed that as the pretreatment duration or power increases, the surface roughness also increase and again a decrease occurs thereafter. As the pretreatment duration or power increased, the Young's modulus and adhesion of WG also increased and then declined. Young's modulus and adhesions average values were compared with ACE inhibitory activity reversely. The result of the CD spectra analysis exhibited losses in the relative percentage of α-helix of WG. Pearson's correlation analysis showed that the average values of Young's modulus and the relative percentage of α-helix correlated with ACE inhibitory activity of the hydrolysates linearly and significantly (P<0.05); the relative percentage of β-sheet correlated linearly with DH of WG significantly (P<0.05). In conclusion, ADFU pretreatment is an efficient method in proteolysis due to its physical and chemical effect on the Young's modulus, α-helix and β-sheet of WG.
Rodriguez, V L; Prewitt Diaz, J O
1990-04-01
The purpose of this study was to explore the correlations among GPA, the Spanish version of the WISC-R, and the Woodcock Johnson Achievement subtests for a group of Puerto Rican children. The tests were administered to a sample of 32 children between the ages of 10 to 12 yr. in Grade 4. Pearson correlations between the Verbal, Performance, and Full Scale scaled scores in the WISC-R (Spanish Edition) ranged between .37 to .83. Correlations between subtests of the Woodcock-Johnson Achievement Test ranged from .26 to .70. The moderate correlation between the Total scaled scores on the Woodcock-Johnson and the scaled scores of the Performance, Verbal, and Full Scales of the Spanish WISC-R is indicative of the value of these Spanish-language instruments in diagnosing the intellectual and academic performance of Spanish-speaking populations in the United States.
Wiesner, M; Beer, J
1991-12-01
For 42 children from rural north central Kansas school districts (27 boys, 15 girls) who were referred for Special Education testing, the WISC-R IQs (Full Scale, Verbal, and Performance), the means on the Expressive One Word Picture Vocabulary Test, the Peabody Picture Vocabulary Test--Revised, and the Test of Language Development were recorded from the children's files. No sex differences on any variable were noted; all variables correlated (Pearson) significantly but varied in magnitude. This group of tests, being intercorrelated, can be used to collect information on children's academic, speech, and language abilities. Valid judgments can be made regarding children's academic abilities for school when multiple tests are administered by professional staff.
ERIC Educational Resources Information Center
Prevost, A. Toby; Mason, Dan; Griffin, Simon; Kinmonth, Ann-Louise; Sutton, Stephen; Spiegelhalter, David
2007-01-01
Practical meta-analysis of correlation matrices generally ignores covariances (and hence correlations) between correlation estimates. The authors consider various methods for allowing for covariances, including generalized least squares, maximum marginal likelihood, and Bayesian approaches, illustrated using a 6-dimensional response in a series of…
Correlation Structures of Correlated Binomial Models and Implied Default Distribution
NASA Astrophysics Data System (ADS)
Mori, Shintaro; Kitsukawa, Kenji; Hisakado, Masato
2008-11-01
We show how to analyze and interpret the correlation structures, the conditional expectation values and correlation coefficients of exchangeable Bernoulli random variables. We study implied default distributions for the iTraxx-CJ tranches and some popular probabilistic models, including the Gaussian copula model, Beta binomial distribution model and long-range Ising model. We interpret the differences in their profiles in terms of the correlation structures. The implied default distribution has singular correlation structures, reflecting the credit market implications. We point out two possible origins of the singular behavior.
Serrano, Pablo Fernandez-Crehuet; Serrano, Jose Luis Fernandez-Crehuet; Allam, Mohamed Farouk; Navajas, Rafael Fernandez-Crehuet
2016-01-01
Background: The presence of noncutaneous neoplasms does not seem to increase the risk of cutaneous malignant melanoma; however, it seems to be associated with the development of other hematological, brain, breast, uterine, and prostatic neoplasms. An ecological transversal study was conducted to study the geographic association between cutaneous malignant melanoma and 24 localizations of cancer in forty European countries. Methods: Cancer incidence rates were extracted from GLOBOCAN database of the International Agency for Research on Cancer. We analyzed the age-adjusted and gender-stratified incidence rates for different localizations of cancer in forty European countries and calculated their correlation using Pearson's correlation test. Results: In males, significant correlations were found between cutaneous malignant melanoma with testicular cancer (r = 0.83 [95% confidence interval (CI): 0.68–0.89]), myeloma (r = 0.68 [95% CI: 0.46–0.81]), prostatic carcinoma (r = 0.66 [95% CI: 0.43–0.80]), and non-Hodgkin lymphoma (NHL) (r = 0.63 [95% CI: 0.39–0.78]). In females, significant correlations were found between cutaneous malignant melanoma with breast cancer (r = 0.80 [95% CI: 0.64–0.88]), colorectal cancer (r = 0.72 [95% CI: 0.52–0.83]), and NHL (r = 0.71 [95% CI: 0.50–0.83]). Conclusions: These correlations call to conduct new studies about the epidemiology of cancer in general and cutaneous malignant melanoma risk factors in particular. PMID:27217938
Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?
Love, J.J.; Mursula, K.; Tsai, V.C.; Perkins, D.M.
2011-01-01
Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868-2008, solar cycles 11-23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically- significant correlation between sunspot number and geomagnetic activity, Pearson p < 10-4, but correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction. ?? 2011 by the American Geophysical Union.
Impact and correlation of environmental conditions on pollen counts in Karachi, Pakistan.
Perveen, Anjum; Khan, Muneeba; Zeb, Shaista; Imam, Asif Ali
2015-02-01
A quantitative and qualitative survey of airborne pollen was performed in the city of Karachi, and the pollen counts were correlated with different climatic conditions. The aim of the study was to determine the possible effect of meteorological factors on airborne pollen distribution in the atmosphere of Karachi city. Pollen sampling was carried out by using Burkard spore Trap for the period of August 2009 to July 2010, and a total of 2,922 pollen grains/m(3) were recorded. In this survey, 22 pollen types were recognized. The highest pollen count was contributed by Poaceae pollen type (1,242 pollen grains/m(3)) followed by Amaranthaceae/Chenopodiaceae (948 pollen grains/m(3)), Cyperus rotundus (195 pollen grains/m(3)) and Prosopis juliflora (169 pollen grains/m(3)). Peak pollen season was in August showing a total of 709 pollen grains/m(3) and lowest pollen count was observed in January-2010. Pearson's chi-square test was performed for the possible correlation of pollen counts and climatic factors. The test revealed significant positive correlation of wind speed with pollen types of Amaranthaceae/Chenopodiaceae; Brassica campestris; Asteraceae; and Thuja orientalis. While the correlation of "average temperature" showed significant positive value with Asteraceae and Tamarix indica pollen types. Negative correlation was observed between humidity/ precipitation and pollen types of Brassica campestris; Daucus carota; Ephedra sp.; and Tamarix indica. In the light of above updated data one could identify various aeroallergens present in the air of Karachi city. PMID:25530143
Hashemi Dehaghi, Zahra; Sheikhtaheri, Abbas; Dehnavi, Fariba
2014-01-01
Background: The association between quality of work life and participation in knowledge management is unknown. Objectives: This study aimed to discover the association between quality of work life of nurse managers and their participation in implementing knowledge management. Materials and Methods: This was a correlational study. All nurse managers (71 people) from 11 hospitals affiliated with the Social Security Organization in Tehran, Iran, were included. They were asked to rate their participation in knowledge management and their quality of work life. Data was gathered by a researcher-made questionnaire (May-June 2012). The questionnaire was validated by content and construct validity approaches. Cronbach’s alpha was used to evaluate reliability. Finally, 50 questionnaires were analyzed. The answers were scored and analyzed using mean of scores, T-test, ANOVA (or nonparametric test, if appropriate), Pearson’s correlation coefficient and linear regression. Results: Nurse managers’ performance to implement knowledge management strategies was moderate. A significant correlation was found between quality of work life of nurse managers and their participation in implementing knowledge management strategies (r = 0.82; P < 0.001). The strongest correlations were found between implementation of knowledge management and participation of nurse managers in decision making (r = 0.82; P < 0.001). Conclusions: Improvement of nurse managers’ work life quality, especially in decision-making, may increase their participation in implementing knowledge management. PMID:25763267
Mead, J R; Fernadez, M; Romagnoli, P A; Secor, W E
2006-02-01
We investigated whether variations in gene expression of enzymes associated with anaerobic resistance of laboratory-derived strains of Trichomonas vaginalis could be detected in a group of 28 clinical isolates with variations in metronidazole sensitivity. We compared isolates by real-time PCR because this method allows for highly sensitive quantification of mRNA and for evaluation of several genes simultaneously. We found that PFOR gene A mRNA levels were highly correlated with PFOR gene B levels, as well as the D subunit of malic enzyme and ferrodoxin. Ferrodoxin mRNA expression was also significantly correlated with that of malic enzyme and hydrogenase. However, when we evaluated relationships between these enzymes and resistance to metronidazole, we found no significant correlations between aerobic or anaerobic in vitro sensitivity to drug and mRNA levels of any of the enzymes tested. Similarly, using a Student's t-test, no significant differences in enzyme mRNA levels were observed between isolates separated by metronidazole resistance or susceptibility. The lack of correlation between gene expression and resistance or susceptibility could be the result of differences in expression at the protein level or because other biochemical pathways or genes are involved in the resistance observed in clinical settings. PMID:16629339
SAW correlator spread spectrum receiver
Brocato, Robert W
2014-04-01
A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.
Waveform correlation by tree matching.
Cheng, Y C; Lu, S Y
1985-03-01
A waveform correlation scheme is presented. The scheme consists of four parts: 1) the representation of waveforms by trees, 2) the definition of basic operations on tree nodes and tree distance, 3) a tree matching algorithm, and 4) a backtracking procedure to find the best node-to-node correlation. This correlation scheme has been implemented. Results show that the scheme has the capability of handling distortions that result from stretching or shrinking of intervals or from missing intervals.
Image correlation and sampling study
NASA Technical Reports Server (NTRS)
Popp, D. J.; Mccormack, D. S.; Sedwick, J. L.
1972-01-01
The development of analytical approaches for solving image correlation and image sampling of multispectral data is discussed. Relevant multispectral image statistics which are applicable to image correlation and sampling are identified. The general image statistics include intensity mean, variance, amplitude histogram, power spectral density function, and autocorrelation function. The translation problem associated with digital image registration and the analytical means for comparing commonly used correlation techniques are considered. General expressions for determining the reconstruction error for specific image sampling strategies are developed.
Is meat quality from Longissimus lumborum samples correlated with other cuts in horse meat?
De Palo, Pasquale; Maggiolino, Aristide; Centoducati, Pasquale; Milella, Paola; Calzaretti, Giovanna; Tateo, Alessandra
2016-03-01
The present work aims to investigate if the variation of each parameter in Longissimus lumborum muscle could correspond to the same or to a similar variation of the parameter in the other muscles. The work presents results of Pearson's correlations between Longissimus lumborum samples and other muscle samples, such as Biceps femoris, Rectus femoris, Semimembranosus, Supraspinatus and Semitendinosus in horse meat. A total of 27 male IHDH (Italian Heavy Draught Horse) breed foals were employed. They were slaughtered at 11 months of age and the above-mentioned muscles were sampled. The Longissimus lumborum muscle showed to be representative of other muscles and of the whole carcass for some chemical parameters (moisture, protein and ash) and for some fatty acids profile patterns such as C12:0, C14:0, total monounsaturated fatty acid and polyunsaturated fatty acid, but poor correlations were recorded for intramuscular fat concentration, rheological and colorimetric parameters. Although almost all the qualitative parameters in meat are affected by the anatomical site and by the muscle, the Longissimus lumborum is often not representative in horse meat with regard to modifications of this parameters.
Oliver, Lorraine
2012-01-01
Objective The mode of influence of the aromas of plant essential oils on human behaviour is largely unclear. This study was designed to assess the potential pharmacological relationships between absorbed 1,8-cineole following exposure to rosemary aroma, cognitive performance and mood. Methods Twenty healthy volunteers performed serial subtraction and visual information processing tasks in a cubicle diffused with the aroma of rosemary. Mood assessments were made pre and post testing, and venous blood was sampled at the end of the session. Pearson correlations were carried out between serum levels of 1,8-cineole, cognitive performance measures and change in mood scores. Results Here we show for the first time that performance on cognitive tasks is significantly related to concentration of absorbed 1,8-cineole following exposure to rosemary aroma, with improved performance at higher concentrations. Furthermore, these effects were found for speed and accuracy outcomes, indicating that the relationship is not describing a 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. PMID:23983963
Producing and Detecting Correlated Atoms
Westbrook, C. I.; Schellekens, M.; Perrin, A.; Krachmalnicoff, V.; Viana Gomes, J.; Trebbia, J.-B.; Esteve, J.; Chang, H.; Bouchoule, I.; Boiron, D.; Aspect, A.; Jeltes, T.; McNamara, J.; Hogervorst, W.; Vassen, W.
2006-11-07
We discuss experiments to produce and detect atom correlations in a degenerate or nearly degenerate gas of neutral atoms. First we treat the atomic analog of the celebrated Hanbury Brown Twiss experiment, in which atom correlations result simply from interference effects without any atom interactions. We have performed this experiment for both bosons and fermions. Next we show how atom interactions produce correlated atoms using the atomic analog of spontaneous four-wave mixing. Finally, we briefly mention experiments on a one dimensional gas on an atom chip in which correlation effects due to both interference and interactions have been observed.
Vega, W H O; Quirino, C R; Serapião, R V; Oliveira, C S; Pacheco, A
2015-07-03
The growth of the Gyr breed in Brazil in terms of genetic gain for milk, along with conditions for market, has led to the use of ovum pick-up in vitro production (OPU-IVP) as a leader in biotechnology for the multiplication of genetic material. The aim of this study was to investigate phenotypic correlations between OPU-IVP-linked characteristics and pregnancy rates registered in an embryo transfer program using Gyr cows as oocyte donors. Data collected from 211 OPU sessions and 298 embryo transfers during the years 2012 and 2013 were analyzed and statistical analysis was performed. Estimates of simple Pearson correlations were calculated for NVcoc and PVcoc (number and proportion of viable cumulus-oocyte complexes, respectively); NcleavD4 and PcleavD4 (number and proportion of cleaved embryos on day 4 of culture, respectively); NTembD7 and PTembD7 (number and proportion of transferable embryos on day 7 of culture, respectively); NPrD30 and PPrD30 (number and proportion of pregnancies 30 days after transfer, respectively); and NPrD60 and PPrD60 (number and proportion of pregnancies 60 days after transfer, respectively). Moderate to moderately high correlations were found for all numerical characteristics, suggesting these as the most suitable parameters for selection of oocyte donors in Gyr programs. NVcoc is proposed as a selection trait due to positive correlations with percentage traits and pregnancy rates 30 and 60 days after transfer.
Gatica-Rojas, Valeska; Cartes-Velásquez, Ricardo; Salgado-Méndez, Rodrigo; Castro-Ramírez, Rodolfo
2016-08-01
[Purpose] This study aimed to determine the correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi. [Subjects and Methods] For the study, nine non-faller elderly practitioners of Tai Chi who were able to maintain a standing posture and walk independently were recruited. Timed one-leg standing and timed up-and-go tests were used as functional balance tests and force platform to measure the center of pressure. The Pearson correlation coefficient was calculated for the timed up-and-go/timed one-leg standing test scores and center of pressure parameter values. [Results] None of the correlations was statistically significant, but moderate correlations were observed between the pairs timed one-leg standing/sway area of center of pressure, timed one-leg standing/standard deviation of center of pressure in the mediolateral direction, timed one-leg standing/mean velocity of center of pressure in the anteroposterior direction, and timed up-and-go test sway area of center of pressure. [Conclusion] Timed one-leg standing is more appropriate than timed up-and-go test for the measurement of functional balance in non-faller elderly practitioners of Tai Chi. PMID:27630430
Kim, Gwang-Won; Jeong, Gwang-Woo
2015-12-16
The aim of this study was to evaluate the white matter (WM) volume change and its correlation with symptom severity in patients with schizophrenia using voxel-based morphometry. A total of 20 patients with schizophrenia and 20 age-matched healthy controls participated in this study. MR image data were processed using SPM8 software with diffeomorphic anatomical registration through an exponentiated Lie algebra (DARTEL) algorithm. The patients with schizophrenia showed significant decreases (P=0.042) in the WM volumes of the temporal lobe and superior frontal gyrus compared with the healthy controls. The WM volumes of the middle temporal gyrus were negatively correlated with the scores of both the Positive Subscale (Pearson's ρ=-0.68, P=0.001) and the Negative Subscale (ρ=-0.71, P=0.0005) in the Positive and Negative Syndrome Scale. In addition, the scores of the General Psychopathology Subscale were negatively correlated with the WM volumes of the superior frontal gyrus (ρ=-0.68, P=0.0009). This study evaluated the WM volume of patients with schizophrenia compared with healthy controls using DARTEI-based voxel-based morphometry and also assessed the correlation of the localized WM volume changes with the Positive and Negative Syndrome Scale. These findings will be useful to understand the neuropathology associated with WM abnormality in schizophrenia. PMID:26485094
Gatica-Rojas, Valeska; Cartes-Velásquez, Ricardo; Salgado-Méndez, Rodrigo; Castro-Ramírez, Rodolfo
2016-01-01
[Purpose] This study aimed to determine the correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi. [Subjects and Methods] For the study, nine non-faller elderly practitioners of Tai Chi who were able to maintain a standing posture and walk independently were recruited. Timed one-leg standing and timed up-and-go tests were used as functional balance tests and force platform to measure the center of pressure. The Pearson correlation coefficient was calculated for the timed up-and-go/timed one-leg standing test scores and center of pressure parameter values. [Results] None of the correlations was statistically significant, but moderate correlations were observed between the pairs timed one-leg standing/sway area of center of pressure, timed one-leg standing/standard deviation of center of pressure in the mediolateral direction, timed one-leg standing/mean velocity of center of pressure in the anteroposterior direction, and timed up-and-go test sway area of center of pressure. [Conclusion] Timed one-leg standing is more appropriate than timed up-and-go test for the measurement of functional balance in non-faller elderly practitioners of Tai Chi. PMID:27630430
Gatica-Rojas, Valeska; Cartes-Velásquez, Ricardo; Salgado-Méndez, Rodrigo; Castro-Ramírez, Rodolfo
2016-08-01
[Purpose] This study aimed to determine the correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi. [Subjects and Methods] For the study, nine non-faller elderly practitioners of Tai Chi who were able to maintain a standing posture and walk independently were recruited. Timed one-leg standing and timed up-and-go tests were used as functional balance tests and force platform to measure the center of pressure. The Pearson correlation coefficient was calculated for the timed up-and-go/timed one-leg standing test scores and center of pressure parameter values. [Results] None of the correlations was statistically significant, but moderate correlations were observed between the pairs timed one-leg standing/sway area of center of pressure, timed one-leg standing/standard deviation of center of pressure in the mediolateral direction, timed one-leg standing/mean velocity of center of pressure in the anteroposterior direction, and timed up-and-go test sway area of center of pressure. [Conclusion] Timed one-leg standing is more appropriate than timed up-and-go test for the measurement of functional balance in non-faller elderly practitioners of Tai Chi.
Gatica-Rojas, Valeska; Cartes-Velásquez, Ricardo; Salgado-Méndez, Rodrigo; Castro-Ramírez, Rodolfo
2016-01-01
[Purpose] This study aimed to determine the correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi. [Subjects and Methods] For the study, nine non-faller elderly practitioners of Tai Chi who were able to maintain a standing posture and walk independently were recruited. Timed one-leg standing and timed up-and-go tests were used as functional balance tests and force platform to measure the center of pressure. The Pearson correlation coefficient was calculated for the timed up-and-go/timed one-leg standing test scores and center of pressure parameter values. [Results] None of the correlations was statistically significant, but moderate correlations were observed between the pairs timed one-leg standing/sway area of center of pressure, timed one-leg standing/standard deviation of center of pressure in the mediolateral direction, timed one-leg standing/mean velocity of center of pressure in the anteroposterior direction, and timed up-and-go test sway area of center of pressure. [Conclusion] Timed one-leg standing is more appropriate than timed up-and-go test for the measurement of functional balance in non-faller elderly practitioners of Tai Chi.
Rosenkranz, Richard R; Welk, Gregory J; Hastmann, Tanis J; Dzewaltowski, David A
2011-07-01
Most studies of psychosocial and demographic correlates of physical activity (PA) have examined relationships across various types of physical and social environments, rather than within a specific environmental behavior setting. The objective of this study was to investigate correlates of PA in structured and unstructured after-school recreation sessions. This study is cross-sectional. School records, questionnaires, and anthropometry were used to obtain demographic and psychosocial variables. Third and fourth-grade children (n = 230) from seven schools wore Actigraph GT1M accelerometers up to six times per year during after-school programming. Accelerometer data were processed to determine percentage of time in moderate-to-vigorous PA (T scores, reflective of an individual child's PA level relative to group mean, were computed for each session and averaged across sessions). Pearson correlations, point-biserial correlations, and mixed-model analyses were used to determine significant associations with PA for each session type (structured and unstructured). For structured sessions, gender, PA barriers self-efficacy, and PA enjoyment were significantly related to PA. For unstructured sessions, only gender was related to PA. Despite equivalent opportunities to participate in active recreation, boys were more active than girls, and children varied in PA level partly due to psychosocial factors. Our results showed that PA self-efficacy and enjoyment explained variability in structured PA sessions.
Diffusion Weighted MR Imaging of Breast and Correlation of Prognostic Factors in Breast Cancer
Kızıldağ Yırgın, İnci; Arslan, Gözde; Öztürk, Enis; Yırgın, Hakan; Taşdemir, Nihat; Gemici, Ayşegül Akdoğan; Kabul, Fatma Çelik; Kaya, Eyüp
2016-01-01
Background: Through Diffusion Weighted Imaging (DWI), information related to early molecular changes, changes in the permeability of cell membranes, and early morphologic and physiologic changes such as cell swelling can be obtained. Aims: We investigated the correlation between the prognostic factors of breast cancer and apparent diffusion coefficient (ADC) in DWI sequences of malignant lesions. Study Design: Retrospective cross-sectional study. Methods: Patients who were referred to our clinic between September 2012 and September 2013, who underwent dynamic breast MRI before or after biopsy and whose biopsy results were determined as malignant, were included in our study. Before the dynamic analysis, DWI sequences were taken. ADC relationship with all prognostic factors was investigated. Pearson correlation test was used to compare the numerical data, while Spearman correlation and Fisher exact tests were used to compare the categorical data. The advanced relationships were evaluated with linear regression analysis and univariate analysis. The efficiency of the parameters was evaluated using ROC analysis. The significance level (P) was accepted as 0.05. Results: In total, 41 female patients with an average age of 49.4 years (age interval 21–77) and 44 lesions were included into the study. In the Pearson correlation test, no statistically significant difference was determined between ADC and the patient’s age and tumor size. In the Spearman correlation test, a statistically significant difference was determined between nuclear grade (NG) and ADC (r=−0.424, p=0.04); no statistically significant correlation was observed between the other prognostic factors with each other and ADC values. In the linear regression analysis, the relationship of NG with ADC was found to be more significant alone than when comparing all parameters (corrected r2=0.196, p=0.005). Further evaluations between the NG and ADC correlation were carried out with ROC analysis. A
Regularized Generalized Canonical Correlation Analysis
ERIC Educational Resources Information Center
Tenenhaus, Arthur; Tenenhaus, Michel
2011-01-01
Regularized generalized canonical correlation analysis (RGCCA) is a generalization of regularized canonical correlation analysis to three or more sets of variables. It constitutes a general framework for many multi-block data analysis methods. It combines the power of multi-block data analysis methods (maximization of well identified criteria) and…
Psychophysical correlations, synchronicity and meaning.
Atmanspacher, Harald
2014-04-01
The dual-aspect framework which Jung developed with Wolfgang Pauli implies that psychophysical phenomena are neither reducible to physical processes nor to conscious mental activity. Rather, they constitute a radically novel kind of phenomena, deriving from correlations between the physical and the mental. In synchronistic events, a particular subclass of psychophysical phenomena, these correlations are explicated as experienced meaning.
Correlation Weights in Multiple Regression
ERIC Educational Resources Information Center
Waller, Niels G.; Jones, Jeff A.
2010-01-01
A general theory on the use of correlation weights in linear prediction has yet to be proposed. In this paper we take initial steps in developing such a theory by describing the conditions under which correlation weights perform well in population regression models. Using OLS weights as a comparison, we define cases in which the two weighting…
Personality Correlates of Polydrug Abuse.
ERIC Educational Resources Information Center
Kilpatrick, Dean G.; And Others
Although the personality correlates of heroin addiction, LSD use, and marijuana smoking have been frequently investigated, relatively few data are available to describe the personality or lifestyle variables correlated with the pattern of polydrug abuse. In an attempt to gather such information, 17 polydrug users, selected from a group of 224…
Optical Correlator Performs Novelty Filtering
NASA Technical Reports Server (NTRS)
Liu, Duncan Tsuen-Hsi; Chao, Tien-Hsin; Cheng, Li-Jen
1994-01-01
Experimental real-time optical correlator performs correlation and novelty filtering in photorefractive crystal. Crystal oriented enabling cross-polarization diffraction: together with polarizing beam splitter, increases signal-to-noise ratio. Laser and optical components expand, collimate, and divide laser beam.
Polarization correlations of Dirac particles
Caban, Pawel; Dziegielewska, Agnieszka; Karmazyn, Anna; Okrasa, Malgorzata
2010-03-15
We calculate the polarization correlation function in the Einstein-Podolsky-Rosen-type experiments with relativistic spin-1/2 particles. This function depends monotonically on the particle momenta. Moreover, we also show that the polarization correlation function violates the Clauser-Horn-Shimony-Holt inequality and the degree of this violation can depend on the particle momenta and the motion of observers.
Squeezed Particle-Antiparticle Correlations
NASA Astrophysics Data System (ADS)
Padula, S. S.; Dudek, D. M.; Socolowski, O., Jr.
2009-04-01
A novel type of correlation involving particle-antiparticle pairs was found out in the 1990's. Currently known as squeezed or Back-to-Back Correlations (BBC), they should be present if the hadronic masses are modified in the hot and dense medium formed in high energy heavy ion collisions. Although well-established theoretically, such hadronic correlations have not yet been observed experimentally. In this phenomenological study we suggest a promising way to search for the BBC signal, by looking into the squeezed correlation function of phi phi and K+ K- pairs at RHIC energies, as function of the pair average momentum, K12=(@BOLD@ k1+@BOLD@ k2)/2. The effects of in-medium mass-shift on the identical particle correlations (Hanbury-Brown and Twiss effect) are also discussed.
Cross-correlation of long-range correlated series
NASA Astrophysics Data System (ADS)
Arianos, Sergio; Carbone, Anna
2009-03-01
A method for estimating the cross-correlation Cxy(τ) of long-range correlated series x(t) and y(t), at varying lags τ and scales n, is proposed. For fractional Brownian motions with Hurst exponents H1 and H2, the asymptotic expression for Cxy(τ) depends only on the lag τ (wide-sense stationarity) and scales as a power of n with exponent H1+H2 for \\tau \\rightarrow 0 . The method is illustrated on: (i) financial series, to show the leverage effect; (ii) genomic sequences, to estimate the correlations between structural parameters along the chromosomes.
Jetté, Marie E.; Gaumnitz, Eric A.; Birchall, Martin A.; Welham, Nathan V.; Thibeault, Susan L.
2014-01-01
Objective While probable causative agents have been identified (e.g., refluxate components, tobacco smoke), the definitive mechanism for inflammation-related laryngeal mucosal damage remains elusive. Multichannel intraluminal impedance combined with pH monitoring (MII/pH) has emerged as a sensitive tool for diagnosis and characterization of gastroesophageal reflux disease (GERD) with laryngopharyngeal manifestations. To determine the relationship between laryngeal signs and MII/pH, we examined correlations between Reflux Finding Score (RFS) ratings of videostroboscopic laryngeal examinations and findings from MII/pH. Study Design Correlational study. Methods Healthy, untreated volunteers (n =142) underwent reflux diagnosis using data acquired from MII/pH testing. Eight trained clinicians performed RFS ratings of corresponding laryngeal examinations. Averaged RFS ratings were compared to MII/pH data using Pearson correlation coefficients. The relationship between RFS and MII/pH findings and demographic/clinical information (age, sex, smoking status, reflux) was assessed using general linear modeling. Rater reliability was evaluated. Results Posterior commissure hypertrophy was negatively correlated with minutes of nonacid refluxate (R=-0.21, p=0.0115). General linear modeling revealed that 28-40% of the variance in ratings of ventricular obliteration, erythema/hyperemia, vocal fold edema, diffuse laryngeal edema, posterior commissure hypertrophy, and granulation/granuloma could be explained by main and interaction effects of age, sex, smoking status, and reflux. Intra- and inter-rater reliability for RFS were poor-fair. Conclusion These results support the theory that the RFS is not specific for reflux in healthy, untreated volunteers, suggesting there may be alternate explanations for inflammatory clinical signs commonly ascribed to reflux in this population. PMID:24782404
On the Hedges Correction for a "t"-Test
ERIC Educational Resources Information Center
VanHoudnos, Nathan M.; Greenhouse, Joel B.
2016-01-01
When cluster randomized experiments are analyzed as if units were independent, test statistics for treatment effects can be anticonservative. Hedges proposed a correction for such tests by scaling them to control their Type I error rate. This article generalizes the Hedges correction from a posttest-only experimental design to more common designs…
Sample Size Tables, "t" Test, and a Prevalent Psychometric Distribution.
ERIC Educational Resources Information Center
Sawilowsky, Shlomo S.; Hillman, Stephen B.
Psychology studies often have low statistical power. Sample size tables, as given by J. Cohen (1988), may be used to increase power, but they are based on Monte Carlo studies of relatively "tame" mathematical distributions, as compared to psychology data sets. In this study, Monte Carlo methods were used to investigate Type I and Type II error…
My Child Doesn't Test Well. Carnegie Perspectives
ERIC Educational Resources Information Center
Bond, Lloyd
2007-01-01
The writer examines a variety of reasons why test performance may not always be a valid measure of a person's competence or potential. Citing that a sizable percentage of students perform well in their schoolwork but poorly on standardized, multiple-choice tests, Bond defines and discusses four candidates as source factors for the phenomenon: (1)…
Kiani, Zahra; Simbar, Masuomeh; Dolatian, Mahrokh; Zayeri, Farid
2016-01-01
Background and Objectives: Women empowerment is one of millennium development goals which is effective on fertility, population’s stability and wellbeing. The influence of social determinants of health (SDH) on women empowerment is documented, however the correlation between SDH and women’s empowerment in fertility has not been figured out yet. This study was conducted to assess correlation between social determinants of health and women’s empowerment in reproductive decisions. Material and Methods: This was a descriptive-correlation study on 400 women who attended health centers affiliated to Shahid Beheshti University of Medical Sciences Tehran-Iran. Four hundred women were recruited using multistage cluster sampling method. The tools for data collection were 6 questionnaires including; 1) socio-demographic characteristics 2) women’s empowerment in reproductive decision-making, 3) perceived social support, 4) self-esteem, 5) marital satisfaction, 6) access to health services. Data were analyzed by SPSS-17 and using Pearson and Spearman correlation tests. Results: Results showed 82.54 ± 14.00 (Mean±SD) of total score 152 of women’s empowerment in reproductive decision making. All structural and intermediate variables were correlated with women’s empowerment in reproductive decisions. The highest correlations were demonstrated between education (among structural determinants; r= 0.44, P< 0.001), and Self-esteem (among intermediate determinants; r= 0.34, P< 0.001) with women’s empowerment in fertility decision making. Conclusion: Social determinants of health have a significant correlation with women’s empowerment in reproductive decision-making. PMID:27157184
Costa, Yuri Martins; Porporatti, André Luís; Hilgenberg-Sydney, Priscila Brenner; Bonjardim, Leonardo Rigoldi; Conti, Paulo César Rodrigues
2015-01-01
Low pressure Pain Threshold (PPT) is considered a risk factor for Temporomandibular Disorders (TMD) and is influenced by psychological variables. Objectives To correlate deep pain sensitivity of masticatory muscles with prosthetic factors and Oral-Health-Related Quality of Life (OHRQoL) in completely edentulous subjects. Material and Methods A total of 29 complete denture wearers were recruited. The variables were: a) Pressure Pain Threshold (PPT) of the masseter and temporalis; b) retention, stability, and tooth wear of dentures; c) Vertical Dimension of Occlusion (VDO); d) Oral Health Impact Profile (OHIP) adapted to orofacial pain. The Kolmogorov-Smirnov test, the Pearson Product-Moment correlation coefficient, the Spearman Rank correlation coefficient, the Point-Biserial correlation coefficient, and the Bonferroni correction (α=1%) were applied to the data. Results The mean age (standard deviation) of the participants was of 70.1 years (9.5) and 82% of them were females. There were no significant correlations with prosthetic factors, but significant negative correlations were found between the OHIP and the PPT of the anterior temporalis (r=-0.50, 95% CI-0.73 to 0.17, p=0.005). Discussion The deep pain sensitivity of masticatory muscles in complete dentures wearers is associated with OHRQoL, but not with prosthetic factors.
COSTA, Yuri Martins; PORPORATTI, André Luís; HILGENBERG-SYDNEY, Priscila Brenner; BONJARDIM, Leonardo Rigoldi; CONTI, Paulo César Rodrigues
2015-01-01
ABSTRACT Low pressure Pain Threshold (PPT) is considered a risk factor for Temporomandibular Disorders (TMD) and is influenced by psychological variables. Objectives To correlate deep pain sensitivity of masticatory muscles with prosthetic factors and Oral-Health-Related Quality of Life (OHRQoL) in completely edentulous subjects. Material and Methods A total of 29 complete denture wearers were recruited. The variables were: a) Pressure Pain Threshold (PPT) of the masseter and temporalis; b) retention, stability, and tooth wear of dentures; c) Vertical Dimension of Occlusion (VDO); d) Oral Health Impact Profile (OHIP) adapted to orofacial pain. The Kolmogorov-Smirnov test, the Pearson Product-Moment correlation coefficient, the Spearman Rank correlation coefficient, the Point-Biserial correlation coefficient, and the Bonferroni correction (α=1%) were applied to the data. Results The mean age (standard deviation) of the participants was of 70.1 years (9.5) and 82% of them were females. There were no significant correlations with prosthetic factors, but significant negative correlations were found between the OHIP and the PPT of the anterior temporalis (r=-0.50, 95% CI-0.73 to 0.17, p=0.005). Discussion The deep pain sensitivity of masticatory muscles in complete dentures wearers is associated with OHRQoL, but not with prosthetic factors. PMID:26814457
Cluster identification based on correlations
NASA Astrophysics Data System (ADS)
Schulman, L. S.
2012-04-01
The problem addressed is the identification of cooperating agents based on correlations created as a result of the joint action of these and other agents. A systematic method for using correlations beyond second moments is developed. The technique is applied to a didactic example, the identification of alphabet letters based on correlations among the pixels used in an image of the letter. As in this example, agents can belong to more than one cluster. Moreover, the identification scheme does not require that the patterns be known ahead of time.
Pseudopotentials for correlated electron systems
NASA Astrophysics Data System (ADS)
Trail, J. R.; Needs, R. J.
2013-07-01
A scheme is developed for creating pseudopotentials for use in correlated-electron calculations. Pseudopotentials for the light elements H, Li, Be, B, C, N, O, and F, are reported, based on data from high-level quantum chemical calculations. Results obtained with these correlated electron pseudopotentials (CEPPs) are compared with data for atomic energy levels and the dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules obtained from coupled cluster single double triple calculations with large basis sets. The CEPPs give better results in correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.
Correlation, Cost Risk, and Geometry
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1992-01-01
The geometric viewpoint identifies the choice of a correlation matrix for the simulation of cost risk with the pairwise choice of data vectors corresponding to the parameters used to obtain cost risk. The correlation coefficient is the cosine of the angle between the data vectors after translation to an origin at the mean and normalization for magnitude. Thus correlation is equivalent to expressing the data in terms of a non orthogonal basis. To understand the many resulting phenomena requires the use of the tensor concept of raising the index to transform the measured and observed covariant components into contravariant components before vector addition can be applied. The geometric viewpoint also demonstrates that correlation and covariance are geometric properties, as opposed to purely statistical properties, of the variates. Thus, variates from different distributions may be correlated, as desired, after selection from independent distributions. By determining the principal components of the correlation matrix, variates with the desired mean, magnitude, and correlation can be generated through linear transforms which include the eigenvalues and the eigenvectors of the correlation matrix. The conversion of the data to a non orthogonal basis uses a compound linear transformation which distorts or stretches the data space. Hence, the correlated data does not have the same properties as the uncorrelated data used to generate it. This phenomena is responsible for seemingly strange observations such as the fact that the marginal distributions of the correlated data can be quite different from the distributions used to generate the data. The joint effect of statistical distributions and correlation remains a fertile area for further research. In terms of application to cost estimating, the geometric approach demonstrates that the estimator must have data and must understand that data in order to properly choose the correlation matrix appropriate for a given estimate
Correlation of neurocognitive function and brain parenchyma volumes in children surviving cancer
NASA Astrophysics Data System (ADS)
Reddick, Wilburn E.; White, Holly A.; Glass, John O.; Mulhern, Raymond K.
2002-04-01
This research builds on our hypothesis that white matter damage and associated neurocognitive symptoms, in children treated for cancer with cranial spinal irradiation, spans a continuum of severity that can be reliably probed using non-invasive MR technology. Quantitative volumetric assessments of MR imaging and psychological assessments were obtained in 40 long-term survivors of malignant brain tumors treated with cranial irradiation. Neurocognitive assessments included a test of intellect (Wechsler Intelligence Test for Children, Wechsler Adult Intelligence Scale), attention (Conner's Continuous Performance Test), and memory (California Verbal Learning Test). One-sample t-tests were conducted to evaluate test performance of survivors against age-adjusted scores from the test norms; these analyses revealed significant impairments in all apriori selected measures of intelligence, attention, and memory. Partial correlation analyses were performed to assess the relationships between brain tissues volumes (normal appearing white matter (NAWM), gray matter, and CSF) and neurocognitive function. Global intelligence (r = 0.32, p = 0.05) and global attentional (r = 0.49, p < 0.01) were significantly positively correlated with NAWM volumes, whereas global memory was significantly positively correlated with overall brain parenchyma (r = 0.38, p = 0.04). We conclude that quantitative assessment of MR examinations in survivors of childhood cancer treated with cranial irradiation reveal that loss of NAWM is associated with decreased intellectual and attentional deficits, whereas overall parenchyma loss, as reflected by increased CSF and decreased white matter, is associated with memory-related deficits.
Prevalence and Correlates of School Bullying Victimization in Xi'an, China.
Zhu, Yuhong; Chan, Ko Ling
2015-01-01
This study used the data from a representative sample to estimate the prevalence of child bullying victimization in Xi'an, China. Data on social demographic information and the experiences of different types of bullying victimization were collected from a randomly selected sample with 3,175 middle school students aged 15-17 years by self-administrated questionnaires. t Test, χ2 test, and multiple logistic regression analyses were used to test group differences and examine the correlates of bullying victimization. Results show that 54.9% and 44.6% of Chinese children have been bullied in a lifetime and in the preceding year, respectively. Correlates for direct and relational bullying victimization includes male participants, father's lower education level, father's unemployment, having one or more siblings, smoking, depression, borderline personality trait, posttraumatic stress disorder, and from rural schools. Overall, the prevalence of child bullying victimization in China is substantial. The multiple correlates suggest prevention and intervention of bullying victimization in a holistic and comprehensive way. PMID:26159148
Prevalence and Correlates of School Bullying Victimization in Xi'an, China.
Zhu, Yuhong; Chan, Ko Ling
2015-01-01
This study used the data from a representative sample to estimate the prevalence of child bullying victimization in Xi'an, China. Data on social demographic information and the experiences of different types of bullying victimization were collected from a randomly selected sample with 3,175 middle school students aged 15-17 years by self-administrated questionnaires. t Test, χ2 test, and multiple logistic regression analyses were used to test group differences and examine the correlates of bullying victimization. Results show that 54.9% and 44.6% of Chinese children have been bullied in a lifetime and in the preceding year, respectively. Correlates for direct and relational bullying victimization includes male participants, father's lower education level, father's unemployment, having one or more siblings, smoking, depression, borderline personality trait, posttraumatic stress disorder, and from rural schools. Overall, the prevalence of child bullying victimization in China is substantial. The multiple correlates suggest prevention and intervention of bullying victimization in a holistic and comprehensive way.
Amani, Reza; Saeidi, Somaye; Nazari, Zahra; Nematpour, Sorour
2010-11-01
It has been suggested that mood disorders and depressive status may be accompanied by lowered zinc status in the body, and adequate consumption of zinc increases a general perceived well-being. The main objective of this study was to assess the correlation between serum zinc concentrations and dietary zinc intakes with depression scores in university female students. In the first phase, Beck's depression questionnaire was applied in a random sampling of 308 selected 20-25-year-old female students (one third of total students in Ahvaz Jondi-Shapour University of Medical Sciences Golestan dormitories) to assess the major depressive disorder (MDD) scales. Then, in the second phase, 23 students who identified as having moderate and severe depression were selected as the case group, and 23 healthy age matched were chosen as the controls. Each of them completed a 12-item semiquantitative food frequency questionnaire containing the main food sources of zinc in the usual dietary patterns and also a 24-h food recall questionnaire to assure the daily zinc intakes. Daily zinc intakes were obtained by multiplying each portion size by its zinc content using food tables. A 5-ml blood sample was taken for further serum zinc status using flame atomic absorption spectrophotometry technique. Pearson's r was used to show the correlation between quantitative variables. Both daily zinc intake and serum zinc concentrations of MDD group were about two thirds of healthy index (p < 0.01). Depressed individuals used to eat lower servings of red meats and chicken as the main food sources of zinc in students' usual diets (p < 0.001). Consumption of other foods as the sources of zinc was not significantly different in two groups. A linear significant correlation between dietary zinc intakes and its serum levels was seen in samples (r = 0.62; p < 0.001) and MDD students (r = 0.55; p < 0.001). There was a linear inverse correlation between Beck questionnaire scores and serum zinc concentrations
Mirrione,M.M.; Mirrione, M.M.; Schulz, D.; Dewey, S.L.; Henn, F.A.
2009-12-06
The learned helplessness paradigm has been repeatedly shown to correlate with neurobiological aspects of depression in humans. In this model, rodents are exposed inescapable foot-shock in order to reveal susceptibility to escape deficit, defined as 'learned helplessness' (LH). Few methods are available to probe the neurobiological aspects underlying the differences in susceptibility in the living animal, thus far being limited to studies examining regional neurochemical changes with microdialysis. With the widespread implementation of small animal neuroimaging methods, including positron emission tomography (PET), it is now possible to explore the living brain on a systems level to define regional changes that may correlate with vulnerability to stress. In this study, 12 wild type Sprague-Dawley rats were exposed to 40 minutes of inescapable foot-shock followed by metabolic imaging using 2-deoxy-2[{sup 18}F]fluoro-D-glucose (18-FDG) 1 hour later. The escape test was performed on these rats 48 hours later (to accommodate radiotracer decay), where they were given the opportunity to press a lever to shut off the shock. A region of interest (ROI) analysis was used to investigate potential correlations (Pearson Regression Coefficients) between regional 18-FDG uptake following inescapable shock and subsequent learned helpless behavior (time to finish the test; number of successful lever presses within 20 seconds of shock onset). ROI analysis revealed a significant positive correlation between time to finish and 18-FDG uptake, and a negative correlation between lever presses and uptake, in the medial thalamic area (p=0.033, p=0.036). This ROI included the paraventricular thalamus, mediodorsal thalamus, and the habenula. In an effort to account for possible spillover artifact, the posterior thalamic area (including ventral medial and lateral portions) was also evaluated but did not reveal significant correlations (p=0.870, p=0.897). No other significant correlations were
Nadorlik, H; Stiver, C; Khan, S; Miao, Y; Holzer, R; Cheatham, J P; Cua, C L
2016-04-01
Newer echocardiographic techniques may allow for more accurate assessment of left ventricular (LV) function. Adult studies have correlated these echocardiographic measurements with invasive data, but minimal data exist in the pediatric congenital heart population. Purpose of this study was to evaluate which echocardiographic measurements correlated best with LV systolic and diastolic catheterization parameters. Patients with two-ventricle physiology who underwent simultaneous echocardiogram and cardiac catheterization were included. Images were obtained in the four-chamber view. LV systolic echocardiographic data included ejection fraction, displacement, tissue Doppler imaging (TDI) s' wave, global longitudinal strain, and strain rate (SR) s' wave. Diastolic echocardiographic data included mitral E and A waves, TDI e' and a' waves, and SRe' and SRa' waves. E/TDI e', TDI e'/TDI a', E/SRe', and SRe'/SRa' ratios were also calculated. Catheterization dP/dt was used as a marker for systolic function, and LV end-diastolic pressure (EDP) was used as a marker for diastolic function. Correlations of the echocardiographic and catheterization values were performed using Pearson correlation. Twenty-nine patients were included (14 females, 15 males). Median age at catheterization was 3.4 years (0.04-17.4 years). dP/dt was 1258 ± 353 mmHg/s, and LVEDP was 10.8 ± 2.4 mmHg. There were no significant correlations between catheterization dP/dt and systolic echocardiographic parameters. LVEDP correlated significantly with SRe' (r = -0.4, p = 0.03), SRa' (r = -0.4, p = 0.03), and E/SRe' (r = 0.5, p = 0.004). In pediatric congenital heart patients, catheterization dP/dt did not correlate with echocardiographic measurements of LV systolic function. Further studies are needed to determine which echocardiographic parameter best describes LV systolic function in this population. Strain rate analysis significantly correlated with LVEDP. Strain rate analysis should be considered as an
Modernizing the JPL VLBI Correlator
NASA Astrophysics Data System (ADS)
Rogstad, S.; Goodhart, C. E.; Clark, J. E.; Finley, S.; Lanyi, G. E.; White, L. A.; Jacobs, Christopher S.>
This poster will present the current capabilities of the JPL VLBI Correlator (JVC) and the general architecture of the equipment. In addition, the scientific and navigation uses of the JVC will be enumerated for background purposes. The JVC is a software correlator based on a Beowulf cluster of computers. It replaces a thirty year old correlator based on custom designed digital hardware. General comparisons between the old and new equipment will be made. The JVC makes use of a separate program, SoftC, to do the actual correlations. The JVC manages the sending of data to multiple machines in a Beowulf cluster each running SoftC in parallel on small chunks of the data. The basic architecture of SoftC will also be described.
Digital correlator with fewer IC's
NASA Technical Reports Server (NTRS)
Apple, G. G.; Rubin, L.
1979-01-01
Digital correlator requires only few integrated circuits to determine synchronization of two 24-bit digital words. Circuit is easily reduced or expanded to accommodate shorter or longer words and can be utilized in industrial and commercial data processing and telecommunications.
Glassy correlations in nematic elastomers
NASA Astrophysics Data System (ADS)
Lu, Bing; Goldbart, Paul; Mao, Xiaoming
2009-03-01
We address the physical properties of an isotropic melt or solution of nematogenic polymers that is then cross-linked beyond the vulcanization point. To do this, we construct a replica Landau theory involving a coupled pair of order- parameter fields: one describing vulcanization, the other describing local nematic order. Thermal nematic fluctuations, present at the time of cross-linking, are trapped by cross- linking into the vulcanized network. The resulting glassy nematic fluctuations are analyzed in the Gaussian approximation in two regimes. When the localization length is shorter than the thermal nematic correlation length, the nematic correlations are well captured as glassy correlations. In the opposite regime, fluctuations in the positions of the localized polymers partially wash out the glassy nematic correlations.
Correlations and Neuronal Population Information.
Kohn, Adam; Coen-Cagli, Ruben; Kanitscheider, Ingmar; Pouget, Alexandre
2016-07-01
Brain function involves the activity of neuronal populations. Much recent effort has been devoted to measuring the activity of neuronal populations in different parts of the brain under various experimental conditions. Population activity patterns contain rich structure, yet many studies have focused on measuring pairwise relationships between members of a larger population-termed noise correlations. Here we review recent progress in understanding how these correlations affect population information, how information should be quantified, and what mechanisms may give rise to correlations. As population coding theory has improved, it has made clear that some forms of correlation are more important for information than others. We argue that this is a critical lesson for those interested in neuronal population responses more generally: Descriptions of population responses should be motivated by and linked to well-specified function. Within this context, we offer suggestions of where current theoretical frameworks fall short.
Electronic correlations in the ironpnictides
Qazilbash, M. M.; Hamlin, J. J.; Baumbach, R. E.; Zhang, Lijun; Singh, David J; Maple, M. B.; Basov, D. N.
2009-01-01
In correlated metals derived from Mott insulators, the motion of an electron is impeded by Coulomb repulsion due to other electrons. This phenomenon causes a substantial reduction in the electron's kinetic energy, leading to remarkable experimental manifestations in optical spectroscopy. The high-transition-temperature (Tc) superconducting cuprates are perhaps the most studied examples of such correlated metals. The occurrence of high-Tc superconductivity in the iron pnictides puts a spotlight on the relevance of correlation effects in these materials. Here, we present an infrared and optical study on single crystals of the iron pnictide superconductor LaFePO. We find clear evidence of electronic correlations in metallic LaFePO with the kinetic energy of the electrons reduced to half of that predicted by band theory of nearly free electrons. We deduce that electronic many-body effects are important in the iron pnictides despite the absence of a Mott transition.
A Correlation of Community College Math Readiness and Student Success
NASA Astrophysics Data System (ADS)
Brown, Jayna Nicole
Although traditional college students are more prepared for college-level math based on college admissions tests, little data have been collected on nontraditional adult learners. The purpose of this study was to investigate relationships between math placement tests and community college students' success in math courses and persistence to degree or certificate completion. Guided by Tinto's theory of departure and student retention, the research questions addressed relationships and predictability of math Computer-adaptive Placement Assessment and Support System (COMPASS) test scores and students' performance in math courses, persistence in college, and degree completion. After conducting correlation and regression analyses, no significant relationships were identified between COMPASS Math test scores and students' performance (n = 234) in math courses, persistence in college, or degree completion. However, independent t test and chi-squared analyses of the achievements of college students who tested into Basic Math (n = 138) vs. Introduction to Algebra (n = 96) yielded statistically significant differences in persistence (p = .039), degree completion (p < .001), performance (p = .008), and progress ( p = .001), indicating students who tested into Introduction to Algebra were more successful and persisted more often to degree completion. In order to improve instructional methods for Basic Math courses, a 3-day professional development workshop was developed for math faculty focusing on current, best practices in remedial math instruction. Implications for social change include providing math faculty with the knowledge and skills to develop new instructional methods for remedial math courses. A change in instructional methods may improve community college students' math competencies and degree achievement.
Local Realism of Macroscopic Correlations
NASA Astrophysics Data System (ADS)
Ramanathan, R.; Paterek, T.; Kay, A.; Kurzyński, P.; Kaszlikowski, D.
2011-08-01
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
Intraclass correlations of periodontal measurements.
Haffajee, A D; Socransky, S S; Goodson, J M; Lindhe, J
1985-03-01
Components of variance and intraclass correlation coefficients were computed for changes in attachment level, pocket depth, gingival and plaque index scores for 5 groups of treated periodontal disease patients and 1 group of untreated subjects with periodontal disease. The intraclass correlation coefficients for attachment level change ranged from 0.011 to 0.165 (median 0.067), while intraclass correlation coefficients for pocket depth changes ranged from -0.009 to 0.178 (median 0.071). These intraclass correlation coefficients were much lower than those computed for changes in measurements of plaque which ranged from 0.086 to 0.568 (median 0.268) or gingival inflammation which ranged from 0.119 to 0.522 (median 0.264). Intraclass correlation coefficients at baseline for pocket depths ranged from 0.000 to 0.199 (median 0.053), for plaque accumulation from 0.121 to 0.531 (median 0.222) and for gingival inflammation from 0.229 to 0.596 (median 0.391). The differences in the intraclass correlation coefficients between pocket depth and attachment level on the one hand and plaque accumulation or gingival inflammation on the other could not be explained on the basis of differences in the measurement scale employed, since collapsing measurement scales had little effect on the intraclass correlation coefficients. The observed larger intraclass correlation coefficients for changes in plaque and gingival indices suggest a larger rôle for host contribution to these measurements. In contrast, the data suggest that the major but by no means the sole factor determining the variability of attachment level or pocket depth changes is the nature of the local factors.
Correlated imaging through atmospheric turbulence
Zhang Pengli; Gong Wenlin; Shen Xia; Han Shensheng
2010-09-15
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.
Nonglobal correlations in collider physics
Moult, Ian; Larkoski, Andrew J.
2016-01-13
Despite their importance for precision QCD calculations, correlations between in- and out-of-jet regions of phase space have never directly been observed. These so-called non-global effects are present generically whenever a collider physics measurement is not explicitly dependent on radiation throughout the entire phase space. In this paper, we introduce a novel procedure based on mutual information, which allows us to isolate these non-global correlations between measurements made in different regions of phase space. We study this procedure both analytically and in Monte Carlo simulations in the context of observables measured on hadronic final states produced in e+e- collisions, though itmore » is more widely applicable.The procedure exploits the sensitivity of soft radiation at large angles to non-global correlations, and we calculate these correlations through next-to-leading logarithmic accuracy. The bulk of these non-global correlations are found to be described in Monte Carlo simulation. They increase by the inclusion of non-perturbative effects, which we show can be incorporated in our calculation through the use of a model shape function. As a result, this procedure illuminates the source of non-global correlations and has connections more broadly to fundamental quantities in quantum field theory.« less
Amit, Priyadarshi; Malhotra, Atul; Kumar, Rahul; Kumar, Lokesh; Patro, Dilip Kumar; Elangovan, Sundar
2015-01-01
Objectives: Preoperative chemotherapy plays a key role in management of bone sarcomas. Postoperative evaluation of histological necrosis has been the gold standard method of assessing response to preoperative chemotherapy. This study was done to evaluate the efficacy of static and dynamic magnetic resonance imaging (MRI) for assessing response preoperatively. Materials and Methods: Our study included 14 patients (12 osteosarcomas and 2 malignant fibrous histiocytomas) with mean age of 21.8 years, treated with preoperative chemotherapy followed by surgery. They were evaluated with static and dynamic MRI twice, before starting chemotherapy and again prior to surgery. Change in tumor volume and slope of signal intensity - time curve were calculated and correlated with percentage of histological necrosis using Pearson correlation test. Results: The change in dynamic MRI slope was significant (P = 0.001). Also, ≥60% reduction in slope of the curve proved to be an indicator of good histological response [positive predictive value (PPV) =80%]. Change in tumor volume failed to show significant correlation (P = 0.071). Although it showed high negative predictive value (NPV = 85.7%), PPV was too low (PPV = 57.14%). Conclusions: Dynamic MRI correctly predicts histological necrosis after administration of preoperative chemotherapy to bone sarcomas. Hence, it can be used as a preoperative indicator of response to neoadjuvant chemotherapy. On the other hand, volumetric assessment by static MRI is not an effective predictor of histological necrosis. This study proves the superiority of dynamic contrast-enhanced study over volumetric study by MRI. PMID:26288521
Park, Jaeyong; Lee, Sang Gil; Bae, Jongjin; Lee, Jung Chul
2015-12-01
[Purpose] This study aimed to provide a predictable evaluation method for the progression of scoliosis in adolescents based on quick and reliable measurements using the naked eye, such as the calcaneal valgus angle of the foot, which can be performed at public facilities such as schools. [Subjects and Methods] Idiopathic scoliosis patients with a Cobb's angle of 10° or more (96 females, 22 males) were included in this study. To identify relationships between factors, Pearson's product-moment correlation coefficient was computed. The degree of scoliosis was set as a dependent variable to predict thoracic and lumbar scoliosis using ankle angle and physique factors. Height, weight, and left and right calcaneal valgus angles were set as independent variables; thereafter, multiple regression analysis was performed. This study extracted variables at a significance level (α) of 0.05 by applying a stepwise method, and calculated a regression equation. [Results] Negative correlation (R=-0.266) was shown between lumbar lordosis and asymmetrical lumbar rotation angles. A correlation (R=0.281) was also demonstrated between left calcaneal valgus angles and asymmetrical thoracic rotation angles. [Conclusion] Prediction of scoliosis progress was revealed to be possible through ocular inspection of the calcaneus and Adams forward bending test and the use of a scoliometer.
Park, Jaeyong; Lee, Sang Gil; Bae, Jongjin; Lee, Jung Chul
2015-12-01
[Purpose] This study aimed to provide a predictable evaluation method for the progression of scoliosis in adolescents based on quick and reliable measurements using the naked eye, such as the calcaneal valgus angle of the foot, which can be performed at public facilities such as schools. [Subjects and Methods] Idiopathic scoliosis patients with a Cobb's angle of 10° or more (96 females, 22 males) were included in this study. To identify relationships between factors, Pearson's product-moment correlation coefficient was computed. The degree of scoliosis was set as a dependent variable to predict thoracic and lumbar scoliosis using ankle angle and physique factors. Height, weight, and left and right calcaneal valgus angles were set as independent variables; thereafter, multiple regression analysis was performed. This study extracted variables at a significance level (α) of 0.05 by applying a stepwise method, and calculated a regression equation. [Results] Negative correlation (R=-0.266) was shown between lumbar lordosis and asymmetrical lumbar rotation angles. A correlation (R=0.281) was also demonstrated between left calcaneal valgus angles and asymmetrical thoracic rotation angles. [Conclusion] Prediction of scoliosis progress was revealed to be possible through ocular inspection of the calcaneus and Adams forward bending test and the use of a scoliometer. PMID:26834376
Verma, KG; Verma, P; Bansal, N; Basavaraju, S; Sachdeva, SK; Khosa, R
2014-01-01
Background: Palatal rugae (PR) are asymmetrical irregular elevations, recorded during maxillary cast fabrication, that can be used for identification purpose if previous comparative sources are available. Aim: This study investigated uniqueness of PR patterns in relation to gender, palatal vault forms, and ABO blood groups in three (North-East [N-E], Northern and Western) populations of India. Subjects and Methods: The study was conducted on randomly selected 90 students, 30 from each sub population. Design - The palatal vault was recorded as Types I, II, and III. The maxillary casts were analyzed for each subject. The blood group of each subject was also recorded. Pearson's correlation coefficient tests were performed on cross-tabulations to evaluate significant relationship among different variables. Results: The PR number was more among females with an insignificant correlation among gender and mean rugae size on both sides. Types I and II hard palate vaults were seen associated with straight forwardly directed PR pattern, while Type III with curved forwardly directed PR. On the right side, straight rugae shape was most common type. On the left side, straight rugae shape was most common in Northern population while in N-E and Western populations curved rugae was the dominating type. A highly significant correlation was found between ABO blood groups and different PR patterns. Conclusions: PR possesses unique characteristics and can be used along with palatal vault forms as well as ABO blood groups for racial and individualistic soft tissue oral print in forensic cases. PMID:25328791
NASA Astrophysics Data System (ADS)
Adjorlolo, Clement; Mutanga, Onisimo; Cho, Moses A.; Ismail, Riyad
2013-04-01
In this paper, a user-defined inter-band correlation filter function was used to resample hyperspectral data and thereby mitigate the problem of multicollinearity in classification analysis. The proposed resampling technique convolves the spectral dependence information between a chosen band-centre and its shorter and longer wavelength neighbours. Weighting threshold of inter-band correlation (WTC, Pearson's r) was calculated, whereby r = 1 at the band-centre. Various WTC (r = 0.99, r = 0.95 and r = 0.90) were assessed, and bands with coefficients beyond a chosen threshold were assigned r = 0. The resultant data were used in the random forest analysis to classify in situ C3 and C4 grass canopy reflectance. The respective WTC datasets yielded improved classification accuracies (kappa = 0.82, 0.79 and 0.76) with less correlated wavebands when compared to resampled Hyperion bands (kappa = 0.76). Overall, the results obtained from this study suggested that resampling of hyperspectral data should account for the spectral dependence information to improve overall classification accuracy as well as reducing the problem of multicollinearity.
Khiavi, Farzad Faraji; Shakhi, Kamal; Dehghani, Roohallah; Zahiri, Mansour
2016-01-01
Introduction Organizational justice is an intricate concept that refers to fair and ethical conduct of individuals within organizations. No research has been conducted on the variables associated with organizational justice in rehabilitation clinics. Thus, the aim of this research was to determine the correlation between organizational justice and organizational trust among the employees of rehabilitation clinics in hospitals of Ahvaz, Iran. Methods This was a cross-sectional research, and it was conducted on 140 rehabilitation staff members of hospital clinics in Ahvaz. The data were gathered using organizational justice and trust questionnaires. The data were analyzed using the independent-samples t-test, ANOVA, and Pearson’s product-moment correlation SPSS software. Results Significant correlations between procedure and interaction justice and organizational trust were identified (p < 0.001). Distributive justice showed small correlation with trust (r = 0.25, p < 0.021). Organizational justice was significantly associated with organizational trust (r = 0.42, p < 0.001). Organizational justice was not significantly related to any demographic variable (p > 0.05). Conclusion There was a positive, medium, and significant correlation between organizational justice and trust. It is suggested that rehabilitation clinics’ managers develop plans to increase their organizational justice subscales in order to develop organizational trust among their employees. PMID:27053997
A scalable correlator for multichannel diffuse correlation spectroscopy
NASA Astrophysics Data System (ADS)
Stapels, Christopher J.; Kolodziejski, Noah J.; McAdams, Daniel; Podolsky, Matthew J.; Fernandez, Daniel E.; Farkas, Dana; Christian, James F.
2016-03-01
Diffuse correlation spectroscopy (DCS) is a technique which enables powerful and robust non-invasive optical studies of tissue micro-circulation and vascular blood flow. The technique amounts to autocorrelation analysis of coherent photons after their migration through moving scatterers and subsequent collection by single-mode optical fibers. A primary cost driver of DCS instruments are the commercial hardware-based correlators, limiting the proliferation of multi-channel instruments for validation of perfusion analysis as a clinical diagnostic metric. We present the development of a low-cost scalable correlator enabled by microchip-based time-tagging, and a software-based multi-tau data analysis method. We will discuss the capabilities of the instrument as well as the implementation and validation of 2- and 8-channel systems built for live animal and pre-clinical settings.
Friedman, Scott D.; Sonnentrucker, Paule; York, Donald G.; Hobbs, L. M.; McCall, Benjamin J.; Dahlstrom, Julie; Welty, Daniel E.; Drosback, Meredith M.; Rachford, Brian L.; Snow, Theodore P.
2011-01-20
We establish correlations between equivalent widths of eight diffuse interstellar bands (DIBs), and examine their correlations with atomic hydrogen, molecular hydrogen, and E{sub B-V}. The DIBs are centered at {lambda}{lambda} 5780.5, 6204.5, 6283.8, 6196.0, 6613.6, 5705.1, 5797.1, and 5487.7, in decreasing order of Pearson's correlation coefficient with N(H) (here defined as the column density of neutral hydrogen), ranging from 0.96 to 0.82. We find the equivalent width (EW) of {lambda}5780.5 is better correlated with column densities of H than with E{sub B-V} or H{sub 2}, confirming earlier results based on smaller data sets. We show that the same is true for six of the seven other DIBs presented here. Despite this similarity, the eight strong DIBs chosen are not correlated well enough with each other to suggest they come from the same carrier. We further conclude that these eight DIBs are more likely to be associated with H than with H{sub 2}, and hence are not preferentially located in the densest, most UV shielded parts of interstellar clouds. We suggest that they arise from different molecules found in diffuse H regions with very little H{sub 2} (molecular fraction f < 0.01). Of the 133 stars with available data in our study, there are three with significantly weaker {lambda}5780.5 than our mean H-{lambda}5780.5 relationship, all of which are in regions of high radiation fields, as previously noted by Herbig. The correlations will be useful in deriving interstellar parameters when direct methods are not available. For instance, with care, the value of N(H) can be derived from W{sub {lambda}}(5780.5).
Bousquet, Jean; Zuberbier, Torsten; Canonica, G Walter; Fokkens, Wytske J; Gopalan, Gokul; Shekar, Tulin
2013-01-01
Allergic rhinitis (AR) symptoms can impart emotional, quality of life (QOL), and work productivity burdens, especially in persistent AR (PER). Desloratadine, an H1-receptor antagonist, has been shown to be effective against nasal and nonnasal AR symptoms and to improve QOL. Exploratory analyses were conducted to evaluate whether desloratadine-mediated symptom improvement correlated with improvements in QOL and productivity. The Aerius Control: Clinical and Evaluative Profile of Treatment 2 (NCT00405964) study was a 12-week, multinational, randomized, placebo-controlled prospective study of once-daily desloratadine at 5 mg in subjects with moderate-to-severe PER. Assessments included twice-daily symptom severity ratings (0 = none to 3 = severe; total and individual symptoms), sleep interference (morning [A.M.]), interference with activities of daily living (ADL; evening [P.M.]), the Rhinoconjunctivitis Quality of Life Questionnaire-Standardized version (baseline and days 29 and 85), and the Work Productivity and Activity Impairment-Allergy-Specific questionnaire (baseline and weekly). Pearson product-moment correlation statistics (r) were determined to assess correlations between symptom score improvements and QOL factors. All desloratadine-treated patients (n = 360) were included in this exploratory analysis. In the desloratadine-treated patients, all correlations tested were positive (all p < 0.0001). The highest coefficients were seen for the correlations between A.M./P.M. PRIOR total five-symptom score and interference with ADL (r = 0.72) and between A.M. NOW congestion and ADL interference (r = 0.69). Continuous daily treatment of moderate-to-severe PER with desloratadine at 5 mg/day significantly improved symptoms, which correlated positively, albeit moderately, with QOL benefits and reversal of functional impairments caused by PER.
Metri, Kashinath G; Bhargav, Hemant; Ramarao, Nagendra Hongasandra; Rizzo-Sierra; Basavakatti, Ramakrishna R
2012-01-01
Purpose: Ayurveda is one of the most ancient systems of medical health care. The basic principles, diagnosis of the diseases and their treatment are based on individual prakriti (constitutional type). Ayurveda further classifies the prakriti of an individual on the basis of a set of psychosomatic attributes of personality, depending on whether this individual belongs to Vata, Pitta, or Kapha prakriti, or any combination of them (Patwardhan et al., 2005). The appropriate prakriti assessment is done by several means including questionnaires (Rastogi, 2012; Shilpa and Venkatesha-Murthy, 2011). We aimed to obtain experimental evidence correlating Ayurveda based tridosha-prakriti with western constitutional psychology somatotypes (Rizzo-Sierra, 2011). Method: We employed our Tridosha-prakriti questionnaire (Ramakrishna and Nagendra, 2012), and compared its results with a set of body composition parameters: Height, body weight, body mass index (BMI), muscle mass, fat mass, and fat percentage in normal healthy volunteers (25 males and 25 females, mean age was 26 (± 4) and 25 (± 6) years respectively). Moreover, two-tailed Pearson's correlations were investigated to match the extreme prakriti types with the western constitutional psychology somatotypes, through the mentioned body composition measures. Result: Significant negative correlations were observed between the percentage of Vata attributes as per the questionnaire in the individuals and their BMI, body weight and fat mass respectively (p<0.05). Similarly, there was a significant positive correlation between the percentage of Pitta attributes with the height, body weight, and muscle mass respectively. Also, a significant positive correlation was observed between the percentage of Kapha attributes with fat mass and fat percentage, along with a negative correlation with height. Conclusion: We provide evidence-linking Ayurveda to modern constitutional psychology. In this way, a concept such as prakriti is suggested
Correlation between inner strength and health-promoting behaviors in women with heart failure
Hosseini, Meimanat; Vasli, Parvaneh; Rashidi, Sakineh; Shahsavari, Soodeh
2016-01-01
Introduction Inner strength is a factor for mental health and well-being and, consequently, a dynamic component of holistic healing. Health-promoting behaviors are appropriate activities to improve health status and prevent the progression of the functional defect resulting from heart failure. The present study aimed to determine the correlation between inner strength and health-promoting behaviors in women with heart failure referred to hospitals affiliated with Shahid Beheshti University of Medical Sciences (SBMU) in 2013. Methods In this cross-sectional study, 145 women with hearth failure were selected through convenient sampling from the clients referred to hospitals affiliated with SBMU. The data collection tool included a three-section questionnaire of personal characteristics, inner strength, and health-promoting life profile II (HPLP II). The data analysis used descriptive statistical tests and Pearson correlation coefficient through SPSS version 20. Results A direct significant correlation was found between inner strength and all dimensions of health-promoting behaviors and overall health-promoting behaviors (p=0.000) as well as between all dimensions of inner strength (except for the dimension of knowing and searching with physical activity and the dimension of connectedness with personal accountability in healthcare as well as connectedness with physical activity) with health-promoting behaviors (p=0.000 to p=0008). Conclusion To improve the level of health and well-being and reduce the costs of care services in women with health failure, close attention should be paid to developing and empowering their inner strength. PMID:27757194
High Blood Glucose Levels Correlate with Tumor Malignancy in Colorectal Cancer Patients
Cui, Ge; Zhang, Ting; Ren, Fan; Feng, Wen-Ming; Yao, Yunliang; Cui, Jie; Zhu, Guo-Liang; Shi, Qi-Lin
2015-01-01
Background Research shows that type 2 diabetes mellitus (T2DM) affects the risk and prognosis of colorectal cancer (CRC). Here, we conducted a retrospective study to investigate whether the clinicopathological features of CRC patients correlate with their blood glucose levels. Material/Methods We enrolled 391 CRC patients hospitalized in our center between 2008 and 2013. Data of their first fasting plasma glucose (FPG) and 2-h postprandial glucose (2hPPG) level after admission, their clinicopathological features, and survival were collected. The correlations between blood glucose level and clinicopathological features were analyzed by Pearson chi-square analysis. Patient survival was analyzed by Kaplan-Meier and Cox-regression analysis. Results There were 116 out of the 391 CRC patients who had high blood glucose level (H-G group, 29.67%), among which 58 (14.83%), 18 (4.60%), and 40 (10.23%) were diabetes mellitus (DM), impaired glucose tolerance (IGT), and impaired fasting glucose (IFG), respectively, while 275 (70.33%) patients had normal glucose level (N-G group). Compared with the N-G group, patients in the H-G group had larger tumor diameters and lower tumor differentiation (p<0.05). A higher ratio of patients in the H-G group also had more advanced TNM staging and more ulcerative CRC gross type (p<0.05). No significant difference was observed in patient overall survival among different glucose groups. No effect of insulin therapy on CRC development and patient survival was observed. Conclusions Blood glucose level in CRC patients correlates significantly with local tumor malignancy, but no significant effect on distant metastasis and patient overall survival was observed. PMID:26644185
Higher plasma level of STIM1, OPG are correlated with stent restenosis after PCI
Li, Haibin; Jiang, Zhian; Liu, Xiangdong; Yang, Zhihui
2015-01-01
Object: Percutaneous Coronary Intervention (PCI) is one of the most effective treatments for Coronary Heart Disease (CHD), but the high rate of In Stent Restenosis (ISR) has plagued clinicians after PCI. We aim to investigate the correlation of plasma Stromal Interaction Molecular 1 (STIM1) and Osteoprotegerin (OPG) level with stent restenosis after PCI. Methods: A total of 100 consecutive patients with Coronary Heart Disease (CHD) received PCI procedure were recruited. Coronary angiography was performed 8 months after their PCI. Then patients were divided into 2 groups: observation group was composed by patients who existing postoperative stenosis after intervention; Control group was composed by patients with no postoperative stenosis. The plasma levels of STIM, OPG in all patients were tested before and after intervention. Pearson correlation and multiple linear regression analysis were performed to analysis the correlation between STIM, OPG level and postoperative stenosis. Results: 35 cases were divided into observation group and other 65 were divided into control group. The plasma levels of STIM, OPG have no statistical difference before their PCI procedure, but we observed higher level of High-sensitivity C-reactive protein (Hs-CRP) existed in observation group. We observed higher level of plasma STIM, OPG in observation group when compared with control group after PCI procedure (P < 0.05). Regression analysis demonstrated that Hs-CRP, STIM1, OPG are independent risk factors for ISR. Conclusion: Elevated levels of plasma STIM1, OPG are independent risk factors for ISR in patients received PCI, which could provide useful information for the restenosis control after PCI. PMID:26885040
A Correlational Study of Scoliosis and Trunk Balance in Adult Patients with Mandibular Deviation
Yang, Yang; Wang, Na; Wang, Wenyong; Ding, Yin; Sun, Shiyao
2013-01-01
Previous studies have confirmed that patients with mandibular deviation often have abnormal morphology of their cervical vertebrae. However, the relationship between mandibular deviation, scoliosis, and trunk balance has not been studied. Currently, mandibular deviation is usually treated as a single pathology, which leads to poor clinical efficiency. We investigated the relationship of spine coronal morphology and trunk balance in adult patients with mandibular deviation, and compared the finding to those in healthy volunteers. 35 adult patients with skeletal mandibular deviation and 10 healthy volunteers underwent anterior X-ray films of the head and posteroanterior X-ray films of the spine. Landmarks and lines were drawn and measured on these films. The axis distance method was used to measure the degree of scoliosis and the balance angle method was used to measure trunk balance. The relationship of mandibular deviation, spine coronal morphology and trunk balance was evaluated with the Pearson correlation method. The spine coronal morphology of patients with mandibular deviation demonstrated an “S” type curve, while a straight line parallel with the gravity line was found in the control group (significant difference, p<0.01). The trunk balance of patients with mandibular deviation was disturbed (imbalance angle >1°), while the control group had a normal trunk balance (imbalance angle <1°). There was a significant difference between the two groups (p<0.01). The degree of scoliosis and shoulder imbalance correlated with the degree of mandibular deviation, and presented a linear trend. The direction of mandibular deviation was the same as that of the lateral bending of thoracolumbar vertebrae, which was opposite to the direction of lateral bending of cervical vertebrae. Our study shows the degree of mandibular deviation has a high correlation with the degree of scoliosis and trunk imbalance, all the three deformities should be clinically evaluated in the
Maddahi, Maryam Sadat; Dolatian, Mahrokh; khoramabadi, Monirsadat; Talebi, Atefeh
2016-01-01
Introduction Low birth weight due to preterm delivery or intrauterine growth restriction (IUGR) is the strongest factor contributing to prenatal, neonatal, and postnatal mortality. Maternal–fetal attachment plays a significant role in maternal and fetal health. Health practices performed by the mother during pregnancy constitute one of the factors that may affect neonatal outcomes. The present study was conducted to identify the relationship between maternal–fetal attachment and health practices during pregnancy with neonatal outcomes. Methods This cross-sectional study was conducted on 315 pregnant women with a gestational age of 33–41 weeks who presented to hospitals in Sirjan (Iran) between December 2014 and February 2015. The data collection tools used included the Health Practices in Pregnancy Questionnaire and the Maternal Fetal Attachment Scale. Data were analyzed using IBM-SPSS version 20, focusing on the Pearson product–moment correlation and the logistic regression model. Statistical significance was set to p<0.05. Results The mean score of maternal–fetal attachment was 60.34, and the mean score of health practices was 123.57. The mean birth weight of the neonates was 3052.38 g. Health practices (p<0.05, r=0.11) and maternal-fetal attachment (p<0.01, r=0.23) were positively and significantly correlated with neonatal outcomes. A significant positive relationship was also observed between maternal–fetal attachment and neonatal outcomes. No significant relationships were observed between health practices during pregnancy and neonatal outcomes. Conclusion Maternal-fetal attachment and health practices during pregnancy are positively and significantly correlated with neonatal outcomes. PMID:27648191
Recirculating cross-correlation detector
Andrews, W.H. Jr.; Roberts, M.J.
1985-01-18
A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.
Community Detection for Correlation Matrices
NASA Astrophysics Data System (ADS)
MacMahon, Mel; Garlaschelli, Diego
2015-04-01
A challenging problem in the study of complex systems is that of resolving, without prior information, the emergent, mesoscopic organization determined by groups of units whose dynamical activity is more strongly correlated internally than with the rest of the system. The existing techniques to filter correlations are not explicitly oriented towards identifying such modules and can suffer from an unavoidable information loss. A promising alternative is that of employing community detection techniques developed in network theory. Unfortunately, this approach has focused predominantly on replacing network data with correlation matrices, a procedure that we show to be intrinsically biased because of its inconsistency with the null hypotheses underlying the existing algorithms. Here, we introduce, via a consistent redefinition of null models based on random matrix theory, the appropriate correlation-based counterparts of the most popular community detection techniques. Our methods can filter out both unit-specific noise and system-wide dependencies, and the resulting communities are internally correlated and mutually anticorrelated. We also implement multiresolution and multifrequency approaches revealing hierarchically nested subcommunities with "hard" cores and "soft" peripheries. We apply our techniques to several financial time series and identify mesoscopic groups of stocks which are irreducible to a standard, sectorial taxonomy; detect "soft stocks" that alternate between communities; and discuss implications for portfolio optimization and risk management.
Correlation of ADC value with pathologic indexes in colorectal tumor homografts in Balb/c mouse
Jiang, Hongnan; Niu, Jinliang; Zheng, Ying
2014-01-01
Objective Noninvasive diffusion-weighted magnetic resonance imaging (DWI) is a well-studied MR imaging technique for quantifying water diffusion especially in tumor area. The correlation between apparent diffusion coefficient (ADC) value and apoptosis or proliferation is not clear by now. This study aimed to investigate whether DWI-ADC value could be used as an imaging marker related with pathologic indexes of tumors. Methods A total of 30 Balb/c mice with HT29 colorectal carcinoma were subjected to DWI and histologic analysis. The percentage of ADC changes and the apoptotic and proliferating indexes were calculated at predefined time points. Kolmogorov-Smirnov distances were considered to determine whether the percentage of ADC changes, and the apoptotic and proliferating indexes were normally distributed. An independent-samples t-test was used to analyze the difference between apoptotic and proliferating indexes in the two groups. Results There was a statistically significant difference in proliferating index between the radiotherapy and control groups (mean proliferating index: 49.27% vs. 83.09%), and there was a statistically significant difference in apoptotic index between the two groups (mean apoptotic index: 37.7% vs. 2.71%). A significant positive correlation was found between the percentage of ADC changes of the viable tissue and apoptotic index. Pearson’s correlation coefficient was 0.655 (P=0.015). A significant negative correlation was found between the percentage of ADC changes of the viable tissue and ki-67 proliferation index. Pearson’s correlation coefficient was 0.734 (P<0.001). Conclusions Our results suggest that ADC value may be used in measurement of cell apoptotic and proliferating indexes in colorectal carcinoma. PMID:25232218
Bravo-Calderón, Diego Mauricio; Lauand, Gustavo Amaral; Assao, Agnes; Suárez-Peñaranda, José-Manuel; Pérez-Sayáns, Mario; García-García, Abel; Marana, Aparecido Nilceu; Nonogaki, Suely; Lauris, José Roberto Pereira; Kowalski, Luiz Paulo
2016-01-01
Background. The beta-2 adrenergic receptor is expressed by neoplastic cells and is correlated with a wide spectrum of tumor cell mechanisms including proliferation, apoptosis, angiogenesis, migration, and metastasis. Objectives. The present study aimed to analyze the expression of the beta-2 adrenergic receptor (β2-AR) in tumor-free surgical margins of oral squamous cell carcinomas (OSCC) and at the invasive front. Sixty-two patients diagnosed with OSCC, confirmed by biopsy, were selected for the study. The clinicopathological data and clinical follow-up were obtained from medical records and their association with β2-AR expression was verified by the chi-square test or Fischer's exact test. To verify the correlation of β2-AR expression in tumor-free surgical margins and at the invasive front of OSCCs, Pearson's correlation coefficient test was applied. Results. The expression of β2-AR presented a statistically significant correlation between the tumor-free surgical margins and the invasive front of OSCC (r = 0.383; p = 0.002). The immunohistochemical distribution of β2-AR at the invasive front of OSCC was also statistically significant associated with alcohol (p = 0.038), simultaneous alcohol and tobacco consumption (p = 0.010), and T stage (p = 0.014). Conclusions. The correlation of β2-AR expression in OSCC and tumor-free surgical margins suggests a role of this receptor in tumor progression and its expression in normal oral epithelium seems to be constitutive. PMID:27042179
Yamamoto, Harumi; Takematsu, Hiromu; Fujinawa, Reiko; Naito, Yuko; Okuno, Yasushi; Tsujimoto, Gozoh; Suzuki, Akemi; Kozutsumi, Yasunori
2007-01-01
Background Glycan biosynthesis occurs though a multi-step process that requires a variety of enzymes ranging from glycosyltransferases to those involved in cytosolic sugar metabolism. In many cases, glycan biosynthesis follows a glycan-specific, linear pathway. As glycosyltransferases are generally regulated at the level of transcription, assessing the overall transcriptional profile for glycan biosynthesis genes seems warranted. However, a systematic approach for assessing the correlation between glycan expression and glycan-related gene expression has not been reported previously. Methodology To facilitate genetic analysis of glycan biosynthesis, we sought to correlate the expression of genes involved in cell-surface glycan formation with the expression of the glycans, as detected by glycan-recognizing probes. We performed cross-sample comparisons of gene expression profiles using a newly developed, glycan-focused cDNA microarray. Cell-surface glycan expression profiles were obtained using flow cytometry of cells stained with plant lectins. Pearson's correlation coefficients were calculated for these profiles and were used to identify enzyme genes correlated with glycan biosynthesis. Conclusions This method, designated correlation index-based responsible-enzyme gene screening (CIRES), successfully identified genes already known to be involved in the biosynthesis of certain glycans. Our evaluation of CIRES indicates that it is useful for identifying genes involved in the biosynthesis of glycan chains that can be probed with lectins using flow cytometry. PMID:18043739
Oliveira, Denise Tostes; Bravo-Calderón, Diego Mauricio; Lauand, Gustavo Amaral; Assao, Agnes; Suárez-Peñaranda, José-Manuel; Pérez-Sayáns, Mario; García-García, Abel; Marana, Aparecido Nilceu; Nonogaki, Suely; Lauris, José Roberto Pereira; Kowalski, Luiz Paulo
2016-01-01
Background. The beta-2 adrenergic receptor is expressed by neoplastic cells and is correlated with a wide spectrum of tumor cell mechanisms including proliferation, apoptosis, angiogenesis, migration, and metastasis. Objectives. The present study aimed to analyze the expression of the beta-2 adrenergic receptor (β2-AR) in tumor-free surgical margins of oral squamous cell carcinomas (OSCC) and at the invasive front. Sixty-two patients diagnosed with OSCC, confirmed by biopsy, were selected for the study. The clinicopathological data and clinical follow-up were obtained from medical records and their association with β2-AR expression was verified by the chi-square test or Fischer's exact test. To verify the correlation of β2-AR expression in tumor-free surgical margins and at the invasive front of OSCCs, Pearson's correlation coefficient test was applied. Results. The expression of β2-AR presented a statistically significant correlation between the tumor-free surgical margins and the invasive front of OSCC (r = 0.383; p = 0.002). The immunohistochemical distribution of β2-AR at the invasive front of OSCC was also statistically significant associated with alcohol (p = 0.038), simultaneous alcohol and tobacco consumption (p = 0.010), and T stage (p = 0.014). Conclusions. The correlation of β2-AR expression in OSCC and tumor-free surgical margins suggests a role of this receptor in tumor progression and its expression in normal oral epithelium seems to be constitutive.
Schwarz, Tino F; Kocken, Mariëlle; Petäjä, Tiina; Einstein, Mark H; Spaczynski, Marek; Louwers, Jacqueline A; Pedersen, Court; Levin, Myron; Zahaf, Toufik; Poncelet, Sylviane; Hardt, Karin; Descamps, Dominique; Dubin, Gary
2010-12-01
This pooled analysis of data from four Phase III clinical trials was undertaken to assess the correlation between levels of anti-human papillomavirus (HPV)-16/18 antibodies in serum and cervicovaginal secretions (CVS) in girls and women vaccinated with the HPV-16/18 AS04-adjuvanted vaccine. Serum and CVS samples were collected from a subset of women aged 10-65 years (N=350) at pre-specified time-points from 7 to 36 months post-vaccination. Anti-HPV-16/18 antibody levels in serum and CVS were measured by enzyme-linked immunosorbent assay. Pearson correlation coefficients between serum and CVS antibody levels, standardized for total immunoglobulin G, were calculated at each time-point in women with detectable antibodies in both serum and CVS. All subjects had seroconverted at Month 7 and remained seropositive through Month 36 for both antigens. Geometric mean titers of anti-HPV-16/18 antibodies in serum were substantially higher at all time-points than those in a control group of women who had cleared a natural HPV infection in another trial. In women with detectable antibodies in both serum and CVS, good correlation was seen between HPV-16/18 antibody levels at all time-points (Pearson correlation coefficient: 0.84-0.92 for HPV-16 and 0.90-0.91 for HPV-18). The strong correlation between levels of HPV-16/18 antibodies in serum and CVS up to 36 months post-vaccination in girls and women vaccinated with the HPV-16/18 AS04-adjuvanted vaccine supports transudation of serum antibodies as the mechanism by which antibodies are introduced into CVS. These CVS antibodies may play a role in the protective efficacy of this vaccine. PMID:21157180
Correlations among Stress Parameters, Meat and Carcass Quality Parameters in Pigs
Dokmanovic, Marija; Baltic, Milan Z.; Duric, Jelena; Ivanovic, Jelena; Popovic, Ljuba; Todorovic, Milica; Markovic, Radmila; Pantic, Srdan
2015-01-01
Relationships among different stress parameters (lairage time and blood level of lactate and cortisol), meat quality parameters (initial and ultimate pH value, temperature, drip loss, sensory and instrumental colour, marbling) and carcass quality parameters (degree of rigor mortis and skin damages, hot carcass weight, carcass fat thickness, meatiness) were determined in pigs (n = 100) using Pearson correlations. After longer lairage, blood lactate (p<0.05) and degree of injuries (p<0.001) increased, meat became darker (p<0.001), while drip loss decreased (p<0.05). Higher lactate was associated with lower initial pH value (p<0.01), higher temperature (p<0.001) and skin blemishes score (p<0.05) and more developed rigor mortis (p<0.05), suggesting that lactate could be a predictor of both meat quality and the level of preslaughter stress. Cortisol affected carcass quality, so higher levels of cortisol were associated with increased hot carcass weight, carcass fat thickness on the back and at the sacrum and marbling, but also with decreased meatiness. The most important meat quality parameters (pH and temperature after 60 minutes) deteriorated when blood lactate concentration was above 12 mmol/L. PMID:25656214
Knezović, Nevenka J; Memić, Mustafa; Mabić, Mirela; Huremović, Jasna; Mikulić, Ivanka
2014-12-01
The aim of this study was to determine the association of cardiovascular disease (CVD) of selected human subjects with the hardness of water they consume. Laboratory testing of physical and chemical parameters of water were made using standardized methods: Standard Methods 19th edn, 1995 (APHA, AWWA & WEF, Washington, DC), and ISO 7888:1985, ISO 10523:1998. Pearson's chi-squared test was used for the statistical analysis of data, with the significance level of 0.05. The obtained data were analysed using the statistical program SPSS 16.0. The study sample consisted of 1,021 individuals divided into two groups: soft water consumers, 603 individuals, and, hard water consumers, 618 individuals. Results indicate that a statistically significant (χ(2) = 5.315; df = 1; p = 0.021) number of individuals with CVD drink soft water. The prevalence of CVD in the age group 45-60 years in the study area where soft water is consumed was 21.3% and in the study area where hard water is consumed the prevalence of CVD was 13.7%. The summary results indicate significant correlation between the prevalence of CVD in the population group who drink soft water. The value of the relative risk is 1.127.
Correlation Between Sonographic and In Vivo Measurement of A1 Pulleys in Trigger Fingers.
Spirig, Andres; Juon, Bettina; Banz, Yara; Rieben, Robert; Vögelin, Esther
2016-07-01
The thickness of 210 A1 pulleys of 21 male and female healthy volunteers in two different age groups (20-35 y and 50-70 y) were measured by ultrasound. In a second group, the thickness of 15 diseased A1 pulleys and 15 A1 pulleys of the corresponding other hand of 10 patients with the clinical diagnosis of trigger finger were measured by ultrasound. During open trigger finger release, a strip of A1 pulley was excised and immediately measured using an electronic caliper. The average pulley thickness of healthy volunteers was 0.43-0.47 mm, compared to 0.77-0.79 mm in patients with trigger finger. Based on the receiver operating characteristic (ROC) curve, a diagnostic cut-off value of the pulley thickness at 0.62 mm was defined in order to differ a trigger finger from a healthy finger (sensitivity and specificity of 85%). The correlation between sonographic and effective intra-operative measurements of pulley thickness was linear and very strong (Pearson coefficient 0.86-0.90). In order to distinguish between healthy and diseased A1 pulleys, 0.62 mm is a simple value to use, which can be applied regardless of age, sex, body mass index (BMI) and height in adults. PMID:27126241
NASA Astrophysics Data System (ADS)
Noda, Isao
2016-11-01
Certain techniques useful in enhancing the features of two-dimensional correlation and codistribution spectra (2DCOS and 2DCDS) are reviewed. 2DCOS sorts out the coordinated or sequential variations of spectral intensities induced by an external perturbation applied to a sample system. 2DCDS is designed to determine the order of the presence of individual species. Pareto scaling of data helps to regulate overwhelmingly strong signal contributions, which may obscure the fine features of 2DCOS and 2DCDS spectra. Pearson unit-variance scaling has some limitations by itself but is useful in some applications. Modified forms of asynchronous 2D spectrum combine the features of both synchronous and asynchronous spectra and can be used as a stand-alone 2D map for the streamlined determination of the sequential order of spectral intensity variations. Null-space projection simplifies congested 2D spectra by eliminating select features, such as contribution from a specific component. Node attenuation is a band narrowing technique suitable for 2D analysis, because it does not produce opposite-sign side lobes. Performance of each technique in enhancing the features of 2D spectra is demonstrated with a model set of experimental spectra.
Structural characteristics and external correlates of the Working Alliance Inventory-Short Form.
Smits, Dave; Luyckx, Koen; Smits, Dirk; Stinckens, Nele; Claes, Laurence
2015-06-01
Controversy remains on the psychometric properties of the Working Alliance Inventory-Short Form (WAI-S). In the present study we first examined the factor structure and reliability of WAI-S scores in a sample of 557 Flemish mental health consumers. Subsequently, we investigated the relationship between early alliance quality and client's psychological dysfunctioning (symptomatic distress, interpersonal functioning and personality pathology). Participants completed the Outcome Questionnaire and the Dimensional Assessment of Personality Pathology-Short Form at start of treatment. The WAI-S was completed after the third treatment session. The structure of the WAI-S was examined using confirmatory factor analysis. Four different factor models were compared. Internal consistencies of the scales were ascertained using the Cronbach's alpha coefficient. Pearson correlations were calculated to determine the relationships between alliance ratings and the independent variables. CFA resulted in a two-factor model, with a Bond component (Contact) and a Task-Goal (Contract) component. Reliability of the WAI-S subscale scores proved to be very good. Symptomatic distress, interpersonal dysfunctioning and personality traits were associated to the Contract component of the alliance, but not to the Contact component. Clinical implications, limitations and suggestions for further research are formulated.
Biometric verification with correlation filters.
Vijaya Kumar, B V K; Savvides, Marios; Xie, Chunyan; Venkataramani, Krithika; Thornton, Jason; Mahalanobis, Abhijit
2004-01-10
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 candidates for the matching precision needed in biometric verification. In particular, advanced correlation filters, such as synthetic discriminant function filters, can offer very good matching performance in the presence of variability in these biometric images (e.g., facial expressions, illumination changes, etc.). We investigate the performance of advanced correlation filters for face, fingerprint, and iris biometric verification. PMID:14735958
Correlative Fluorescence and Electron Microscopy
Schirra, Randall T.; Zhang, Peijun
2014-01-01
Correlative fluorescence and electron microscopy (CFEM) is a multimodal technique that combines dynamic and localization information from fluorescence methods with ultrastructural data from electron microscopy, to give new information about how cellular components change relative to the spatiotemporal dynamics within their environment. In this review, we will discuss some of the basic techniques and tools of the trade for utilizing this attractive research method, which is becoming a very powerful tool for biology labs. The information obtained from correlative methods has proven to be invaluable in creating consensus between the two types of microscopy, extending the capability of each, and cutting the time and expense associate with using each method separately for comparative analysis. The realization of the advantages of these methods in cell biology have led to rapid improvement in the protocols and have ushered in a new generation of instruments to reach the next level of correlation – integration. PMID:25271959
Softc: An Operational Software Correlator
NASA Technical Reports Server (NTRS)
Lowe, Stephen T.
2004-01-01
Softc has been used operationally for spacecraft navigation at JPL for over 2 years and will be JPL's Mark 5 correlator next year. Softc was written to be as close to an ideal correlator as possible, making approximations only below 10(exp -13) seconds. The program can correlate real USB, real LSB, or complex I/Q data sampled with 1, 2, 4. or 8-bit resolution, and was developed with strong debugging tools that made final debugging relatively quick. Softc's algorithms and program structure are fully documented. Timing tests on a recent Intel CPU show Softc processes 8 lags of 1-bit sampled data at 10 MSamples/sec, independent of sample rate.
Correlated optical and isotopic nanoscopy
Saka, Sinem K.; Vogts, Angela; Kröhnert, Katharina; Hillion, François; Rizzoli, Silvio O; Wessels, Johannes T.
2014-01-01
The isotopic composition of different materials can be imaged by secondary ion mass spectrometry. In biology, this method is mainly used to study cellular metabolism and turnover, by pulsing the cells with marker molecules such as amino acids labelled with stable isotopes (15N, 13C). The incorporation of the markers is then imaged with a lateral resolution that can surpass 100 nm. However, secondary ion mass spectrometry cannot identify specific subcellular structures like organelles, and needs to be correlated with a second technique, such as fluorescence imaging. Here, we present a method based on stimulated emission depletion microscopy that provides correlated optical and isotopic nanoscopy (COIN) images. We use this approach to study the protein turnover in different organelles from cultured hippocampal neurons. Correlated optical and isotopic nanoscopy can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures. PMID:24718107
Ruuska, T; Vesikari, T; Delem, A; André, F E; Beards, G M; Flewett, T H
1990-01-01
A single oral dose of bovine rotavirus vaccine RIT 4237 or placebo was given to 2 groups of 5-day-old infants, born in October 1984 (n = 244) and June 1985 (n = 245), who remained in follow-up for 2.8 and 2.0 years, respectively. The vaccine had no effect on the total number of detectable episodes of rotavirus diarrhoea: there were 22 cases in the vaccinees and 24 in the placebo recipients in the October group and 18 and 16 respectively in the June group. However, vaccination decreased significantly the clinical severity of rotavirus diarrhoea, as assessed by a numerical score 0-20; this vaccine effect was much greater in the infants born in October. The mean severity scores for vaccine and placebo recipients were 4.55 and 10.75 respectively in the October group (p less than 0.0001, t-test) and 8.2 and 11.6 respectively in the June group (p = 0.010, t-test). Vaccine-induced clinical protection against rotavirus diarrhoea did not correlate well with serological response after vaccination, but showed good correlation to the presence of rotavirus antibodies before the rotavirus epidemic season. It is concluded that bovine rotavirus vaccine is more efficacious when given immediately before the rotavirus epidemic season: the vaccine effect may be amplified by exposure to wild rotaviruses during the season.
Converting Coherence to Quantum Correlations
NASA Astrophysics Data System (ADS)
Ma, Jiajun; Yadin, Benjamin; Girolami, Davide; Vedral, Vlatko; Gu, Mile
2016-04-01
Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here, we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in nonentangled states. We prove that the creation of quantum discord with multipartite incoherent operations is bounded by the amount of quantum coherence consumed in its subsystems during the process. We show how the interplay between quantum coherence consumption and creation of quantum discord works in the preparation of multipartite quantum correlated states and in the model of deterministic quantum computation with one qubit.
Correlation properties of loose groups
Maia, M.A.G.; Da Costa, L.N. )
1990-02-01
The two-point spatial correlation function for loose groups of galaxies is computed, using the recently compiled catalog of groups in the southern hemisphere. It is found that the correlation function for groups has a similar slope to that of galaxies but with a smaller amplitude, confirming an earlier result obtained from a similar analysis of the CfA group catalog. This implies that groups of galaxies are more randomly distributed than galaxies, which may be consistent with the predictions of Kashlinsky (1987) for a gravitational clustering scenario for the formation of large-scale structures. 21 refs.
Converting Coherence to Quantum Correlations.
Ma, Jiajun; Yadin, Benjamin; Girolami, Davide; Vedral, Vlatko; Gu, Mile
2016-04-22
Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here, we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in nonentangled states. We prove that the creation of quantum discord with multipartite incoherent operations is bounded by the amount of quantum coherence consumed in its subsystems during the process. We show how the interplay between quantum coherence consumption and creation of quantum discord works in the preparation of multipartite quantum correlated states and in the model of deterministic quantum computation with one qubit.
Defect Detection in Correlated Noise
NASA Astrophysics Data System (ADS)
Dogandžić, Aleksandar; Eua-Anant, Nawanat
2004-02-01
We present methods for detecting NDE defect signals in correlated noise having unknown covariance. The proposed detectors are derived using the statistical theory of generalized likelihood ratio (GLR) tests and multivariate analysis of variance (MANOVA). We consider both real and complex data models. To allow accurate estimation of the noise covariance, we incorporate secondary data containing only noise into detector design. Probability distributions of the GLR test statistics are derived under the null hypothesis, i.e. assuming that the signal is absent, and used for detector design. We apply the proposed methods to simulated and experimental data and demonstrate their superior performance compared with the detectors that neglect noise correlation.
PREFACE: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Saxena, Siddharth S.; Littlewood, P. B.
2012-07-01
This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to 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
EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Ronning, Filip; Batista, Cristian
2011-03-01
Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 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
Tetrachoric Correlation: A Permutation Alternative
ERIC Educational Resources Information Center
Long, Michael A.; Berry, Kenneth J.; Mielke, Paul W., Jr.
2009-01-01
An exact permutation test is provided for the tetrachoric correlation coefficient. Comparisons with the conventional test employing Student's t distribution demonstrate the necessity of using the permutation approach for small sample sizes and/or disproportionate marginal frequency totals. (Contains 4 tables.)
Octupole correlation effects in nuclei
Chasman, R.R.
1992-01-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Sample Size and Correlational Inference
ERIC Educational Resources Information Center
Anderson, Richard B.; Doherty, Michael E.; Friedrich, Jeff C.
2008-01-01
In 4 studies, the authors examined the hypothesis that the structure of the informational environment makes small samples more informative than large ones for drawing inferences about population correlations. The specific purpose of the studies was to test predictions arising from the signal detection simulations of R. B. Anderson, M. E. Doherty,…
Octupole correlation effects in nuclei
Chasman, R.R.
1992-08-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Unorthodox Uses of Correlation Coefficients.
ERIC Educational Resources Information Center
Kraemer, Helena Chmura
While the potential use of correlation methods has spread to wide contexts and these uses have permeated behavioral research, their scope remains the orthodox applications: to test independence, and to measure association. It is well worth noticing that problems having no obstensible connection to dependence, independence, or association have been…
Multilevel Modeling with Correlated Effects
ERIC Educational Resources Information Center
Kim, Jee-Seon; Frees, Edward W.
2007-01-01
When there exist omitted effects, measurement error, and/or simultaneity in multilevel models, explanatory variables may be correlated with random components, and standard estimation methods do not provide consistent estimates of model parameters. This paper introduces estimators that are consistent under such conditions. By employing generalized…
In vivo correlation mapping microscopy
NASA Astrophysics Data System (ADS)
McGrath, James; Alexandrov, Sergey; Owens, Peter; Subhash, Hrebesh; Leahy, Martin
2016-04-01
To facilitate regular assessment of the microcirculation in vivo, noninvasive imaging techniques such as nailfold capillaroscopy are required in clinics. Recently, a correlation mapping technique has been applied to optical coherence tomography (OCT), which extends the capabilities of OCT to microcirculation morphology imaging. This technique, known as correlation mapping optical coherence tomography, has been shown to extract parameters, such as capillary density and vessel diameter, and key clinical markers associated with early changes in microvascular diseases. However, OCT has limited spatial resolution in both the transverse and depth directions. Here, we extend this correlation mapping technique to other microscopy modalities, including confocal microscopy, and take advantage of the higher spatial resolution offered by these modalities. The technique is achieved as a processing step on microscopy images and does not require any modification to the microscope hardware. Results are presented which show that this correlation mapping microscopy technique can extend the capabilities of conventional microscopy to enable mapping of vascular networks in vivo with high spatial resolution in both the transverse and depth directions.
The Seduction of Correlational Data.
ERIC Educational Resources Information Center
Cochran, Nancy
1979-01-01
A dependency on correlational data allows one to avoid theory building and even to avoid defining terms. The social science community is being seduced by data and would do well to resist what is available simply because of its ease of tabulation and redundancy. (RL)
Correlating P-wave Velocity with the Physico-Mechanical Properties of Different Rocks
NASA Astrophysics Data System (ADS)
Khandelwal, Manoj
2013-04-01
In mining and civil engineering projects, physico-mechanical properties of the rock affect both the project design and the construction operation. Determination of various physico-mechanical properties of rocks is expensive and time consuming, and sometimes it is very difficult to get cores to perform direct tests to evaluate the rock mass. The purpose of this work is to investigate the relationships between the different physico-mechanical properties of the various rock types with the P-wave velocity. Measurement of P-wave velocity is relatively cheap, non-destructive and easy to carry out. In this study, representative rock mass samples of igneous, sedimentary, and metamorphic rocks were collected from the different locations of India to obtain an empirical relation between P-wave velocity and uniaxial compressive strength, tensile strength, punch shear, density, slake durability index, Young's modulus, Poisson's ratio, impact strength index and Schmidt hammer rebound number. A very strong correlation was found between the P-wave velocity and different physico-mechanical properties of various rock types with very high coefficients of determination. To check the sensitivity of the empirical equations, Students t test was also performed, which confirmed the validity of the proposed correlations.
Correlation analysis of urine metabolites and clinical staging in patients with ovarian cancer.
Jiang, Ting; Lin, Yunliang; Yin, Haiqin; Wang, Shanshan; Sun, Qinglei; Zhang, Peihai; Bi, Wenxiang
2015-01-01
This study is to investigate the correlation between urine metabolites and clinical staging in patients with ovarian cancer. The urina sanguinis from 56 cases of primary epithelial ovarian cancer patients and 15 healthy volunteers was collected and the urine metabolites were extracted. Ultra high performance liquid chromatography/time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis was performed. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to analyze the mass spectrometry data. Database retrieval and comparison of the screened metabolites were performed and one-way ANOVA and least significant difference (LSD) t test were carried out. PCA analysis of UPLC-Q-TOF-MS results showed that the score plots of samples from healthy people and patients with ovarian cancer at different clinical stages were separated. Further PLS-DA analysis significantly improved the classification results. The R(2)X was 0.757, the R(2)Y was 0.977 and the Q(2)Y was 0.87, indicating that the model stability and predictability were good. Eight metabolites, including N-acetylneuraminic acid-9-phosphate, 5'-methioadenosine, uric acid-3-nucleoside, pseudouridine, L-valine, succinic acid, L-proline and β-nicotinamide mononucleotide were identified. The contents of these metabolites increased with the development of the disease. There was correlation between urine metabolites and clinical staging in patients with ovarian cancer. PMID:26770415
Strom, Suzanne L.; Anderson, Craig L.; Yang, Luanna; Canales, Cecilia; Amin, Alpesh; Lotfipour, Shahram; McCoy, C. Eric; Langdorf, Mark I.
2015-01-01
Introduction Traditional Advanced Cardiac Life Support (ACLS) courses are evaluated using written multiple-choice tests. High-fidelity simulation is a widely used adjunct to didactic content, and has been used in many specialties as a training resource as well as an evaluative tool. There are no data to our knowledge that compare simulation examination scores with written test scores for ACLS courses. Objective To compare and correlate a novel high-fidelity simulation-based evaluation with traditional written testing for senior medical students in an ACLS course. Methods We performed a prospective cohort study to determine the correlation between simulation-based evaluation and traditional written testing in a medical school simulation center. Students were tested on a standard acute coronary syndrome/ventricular fibrillation cardiac arrest scenario. Our primary outcome measure was correlation of exam results for 19 volunteer fourth-year medical students after a 32-hour ACLS-based Resuscitation Boot Camp course. Our secondary outcome was comparison of simulation-based vs. written outcome scores. Results The composite average score on the written evaluation was substantially higher (93.6%) than the simulation performance score (81.3%, absolute difference 12.3%, 95% CI [10.6–14.0%], p<0.00005). We found a statistically significant moderate correlation between simulation scenario test performance and traditional written testing (Pearson r=0.48, p=0.04), validating the new evaluation method. Conclusion Simulation-based ACLS evaluation methods correlate with traditional written testing and demonstrate resuscitation knowledge and skills. Simulation may be a more discriminating and challenging testing method, as students scored higher on written evaluation methods compared to simulation. PMID:26594288
Ishikawa, Toru; Abe, Satoshi; Hoshii, Asami; Yamada, Yumi; Iiduka, Akihiko; Nemoto, Takeo; Takeda, Keiko; Yoshida, Toshiaki
2016-01-01
Background & Aims The amount of drug-loaded lipiodol in an HCC tumor post-transarterial chemoembolization (TACE) correlates with the risk of local tumor recurrence. Lipiodol enhancement of a tumor on conventional CT, measured in Hounsfield units (HU), can predict tumor response. Here we investigate whether cone-beam CT (CBCT) can also be used to predict tumor response, providing the benefit of being able to optimize the patient’s treatment plan intra-procedurally. Methods A total of 82 HCC nodules (82 patients), ≤5 cm in diameter, were treated with balloon-occluded TACE using miriplatin between December 2013 and November 2014. For each patient, both CBCT and conventional CT images were obtained post-TACE. The degree of correlation between CBCT and conventional CT was determined by comparing identical regions of interest for each imaging modality using pixel values. Results The pixel values from conventional CT and CBCT were highly correlated, with a Pearson correlation coefficient of 0.912 (p<0.001). The location of the nodules within the liver did not affect the results; the correlation coefficient was 0.891 (p<0.001) for the left lobe and 0.926 (p<0.001) for the right lobe. The mean pixel value for conventional CT was 439 ± 279 HU, and the mean pixel value for CBCT was 416 ± 311 HU. Conclusions CBCT may be used as a substitute for conventional CT to quantitatively evaluate the amount of drug-loaded lipiodol within an HCC nodule and, hence, the efficacy of TACE treatment. The major benefit of using CBCT is the ability to predict the likelihood of local recurrence intra-procedurally, enabling subsequent treatment optimization. PMID:26752696
CORRELATION ANALYSIS BETWEEN TIBET AS-γ TeV COSMIC RAY AND WMAP NINE-YEAR DATA
Yin, Qian-Qing; Zhang, Shuang-Nan
2015-08-01
The WMAP team subtracted template-based foreground models to produce foreground-reduced maps, and masked point sources and uncertain sky regions directly; however, whether foreground residuals exist in the WMAP foreground-reduced maps is still an open question. Here, we use Pearson correlation coefficient analysis with AS-γ TeV cosmic ray (CR) data to probe possible foreground residuals in the WMAP nine-year data. The correlation results between the CR and foreground-contained maps (WMAP foreground-unreduced maps, WMAP template-based, and Maximum Entropy Method foreground models) suggest that: (1) CRs can trace foregrounds in the WMAP data; (2) at least some TeV CRs originate from the Milky Way; (3) foregrounds may be related to the existence of CR anisotropy (loss-cone and tail-in structures); (4) there exist differences among different types of foregrounds in the decl. range of <15°. Then, we generate 10,000 mock cosmic microwave background (CMB) sky maps to describe the cosmic variance, which is used to measure the effect of the fluctuations of all possible CMB maps to the correlations between CR and CMB maps. Finally, we do correlation analysis between the CR and WMAP foreground-reduced maps, and find that: (1) there are significant anticorrelations; and (2) the WMAP foreground-reduced maps are credible. However, the significant anticorrelations may be accidental, and the higher signal-to-noise ratio Planck SMICA map cannot reject the hypothesis of accidental correlations. We therefore can only conclude that the foreground residuals exist with ∼95% probability.
Correlation Techniques for Application in Photon Correlation Spectroscopy.
NASA Astrophysics Data System (ADS)
Courtney, Peter R.
Available from UMI in association with The British Library. Requires signed TDF. In this thesis the application of modern computing and electronics to the techniques used in photon correlation spectroscopy is investigated. The study leads to the development of a computer controlled full correlator system based on the TMS32010 digital signal processor, installed in a PC -type microprocessor. A suite of computer control programs are developed featuring full correlation, computer optimization of sampling frequency, dust discrimination and automatic operation. The system was fully tested both on simulated data and during the study of experimental solutions. It was shown to exhibit improved signal to noise, stability, resolution and ease of use over the existing clipping correlator, in addition to being independent of the statistics of the scattered light field. Designs for further development of the system are discussed. Polymer dynamics have been investigated in the study of diisooctylphthalate as a solvent for polystyrene. It was seen to exhibit Theta solvent behaviour at low concentrations with gelation occurring as the concentration increases. At elevated temperatures competing effects produce an initial rise in D _ c followed by a subsequent fall with increasing concentration until a stable level is reached. Dynamics of the Human Immunoglobulins 1gG were studied in solutions approximating to in-vivo conditions. Translational diffusion and bulk rotation was observed for all subclasses, and the movement of Fab arms about the hinge region was conclusively observed for 1gG1 and 1gG3. The characterisation reinforces existing structural models and facilitates further investigations which would be greatly enhanced by the application of techniques developed in this thesis.
In Vivo Fluorescence Correlation and Cross-Correlation Spectroscopy
NASA Astrophysics Data System (ADS)
Mütze, Jörg; Ohrt, Thomas; Petrášek, Zdeněk; Schwille, Petra
In this manuscript, we describe the application of Fluorescence Correlation Spectroscopy (FCS), Fluorescence Cross-Correlation Spectroscopy (FCCS), and scanning FCS (sFCS) to two in vivo systems. In the first part, we describe the application of two-photon standard and scanning FCS in Caenorhabditis elegans embryos. The differentiation of a single fertilized egg into a complex organism in C. elegans is regulated by a number of protein-dependent processes. The oocyte divides asymmetrically into two daughter cells of different developmental fate. Two of the involved proteins, PAR-2 and NMY-2, are studied. The second investigated system is the mechanism of RNA interference in human cells. An EGFP based cell line that allows to study the dynamics and localization of the RNA-induced silencing complex (RISC) with FCS in vivo is created, which has so far been inaccessible with other experimental methods. Furthermore, Fluorescence Cross-Correlation Spectroscopy is employed to highlight the asymmetric incorporation of labeled siRNAs into RISC.
Separating Spike Count Correlation from Firing Rate Correlation.
Vinci, Giuseppe; Ventura, Valérie; Smith, Matthew A; Kass, Robert E
2016-05-01
Populations of cortical neurons exhibit shared fluctuations in spiking activity over time. When measured for a pair of neurons over multiple repetitions of an identical stimulus, this phenomenon emerges as correlated trial-to-trial response variability via spike count correlation (SCC). However, spike counts can be viewed as noisy versions of firing rates, which can vary from trial to trial. From this perspective, the SCC for a pair of neurons becomes a noisy version of the corresponding firing rate correlation (FRC). Furthermore, the magnitude of the SCC is generally smaller than that of the FRC and is likely to be less sensitive to experimental manipulation. We provide statistical methods for disambiguating time-averaged drive from within-trial noise, thereby separating FRC from SCC. We study these methods to document their reliability, and we apply them to neurons recorded in vivo from area V4 in an alert animal. We show how the various effects we describe are reflected in the data: within-trial effects are largely negligible, while attenuation due to trial-to-trial variation dominates and frequently produces comparisons in SCC that, because of noise, do not accurately reflect those based on the underlying FRC.
Automated Gait and Balance Parameters Diagnose and Correlate with Severity in Parkinson Disease
Dewey, Daniel C.; Miocinovic, Svjetlana; Bernstein, Ira; Khemani, Pravin; Dewey, Richard B.; Querry, Ross; Chitnis, Shilpa; Dewey, Richard B.
2014-01-01
Objective To assess the suitability of instrumented gait and balance measures for diagnosis and estimation of disease severity in PD. Methods Each subject performed iTUG (instrumented Timed-Up-and-Go) and iSway (instrumented Sway) using the APDM® Mobility Lab. MDS-UPDRS parts II and III, a postural instability and gait disorder (PIGD) score, the mobility subscale of the PDQ-39, and Hoehn & Yahr stage were measured in the PD cohort. Two sets of gait and balance variables were defined by high correlation with diagnosis or disease severity and were evaluated using multiple linear and logistic regressions, ROC analyses, and t-tests. Results 135 PD subjects and 66 age-matched controls were evaluated in this prospective cohort study. We found that both iTUG and iSway variables differentiated PD subjects from controls (area under the ROC curve was 0.82 and 0.75 respectively) and correlated with all PD severity measures (R2 ranging from 0.18 to 0.61). Objective exam-based scores correlated more strongly with iTUG than iSway. The chosen set of iTUG variables was abnormal in very mild disease. Age and gender influenced gait and balance parameters and were therefore controlled in all analyses. Interpretation Our study identified sets of iTUG and iSway variables which correlate with PD severity measures and differentiate PD subjects from controls. These gait and balance measures could potentially serve as markers of PD progression and are under evaluation for this purpose in the ongoing NIH Parkinson Disease Biomarker Program. PMID:25082782
Kuo, Wen-Hsiu; Jian, Deng-Wei; Wang, Tyng-Guey; Wang, Yi-Chian
2013-08-01
This study aimed to quantify neck muscle stiffness in the normal population with ultrasound elastography. We applied the acoustic radiation force impulse technique and measured shear wave velocities (SWVs) as representative values. The mean ± standard deviation values of SWV in 20 healthy volunteers were 2.09 ± 0.45, 1.21 ± 0.30, 1.12 ± 0.17 and 0.97 ± 0.10 m/s for the trapezius, levator scapulae, scalene anterior and sternocleidomastoid muscles, respectively. The SWV values of the four muscles significantly differed (Kruskal-Wallis test, p < 0.001). The SWV values for the trapezius muscle correlated with body mass indexes (Pearson's correlation, p = 0.034). Subjects with chronic neck pain symptoms had significantly stiffer trapezius muscle (Mann-Whitney U test, p = 0.008). This study demonstrated the technique and feasibility of quantifying neck muscle stiffness using acoustic radiation force impulse elastography and shear wave velocity detection. Further study is necessary to evaluate its diagnostic power in assessing various neck muscle diseases.
Gulan, Ljiljana; Milenkovic, Biljana; Stajic, Jelena M; Vuckovic, Biljana; Krstic, Dragana; Zeremski, Tijana; Ninkov, Jordana
2013-09-01
This paper reports the results of radioactivity concentrations and heavy metal content in soil samples collected from non-agricultural areas in the municipality and vicinity of North Kosovska Mitrovica, formerly the most important mining area in Europe. The estimated average activity concentrations of (226)Ra, (232)Th, (40)K and (137)Cs are 40.6 ± 19, 48 ± 25.4, 743.2 ± 200.5 and 81 ± 119 Bq kg(-1), respectively. The estimated average absorbed dose rate in the air and the annual effective dose are 78.7 nGy h(-1) and 96.6 μSv, respectively. The radium equivalent activity and external hazard index were also calculated. High contents of Pb, Zn, Cu, Cd, As and Ni were found in the analyzed soil samples, thus indicating pollution of the environment. Most metals have a wide range of values spanning 2 to 3 orders of magnitude, which is particularly evident for Pb and Zn. Correlations between the activity concentrations of the radionuclides, the heavy metal content in soil and the basic soil properties were determined by means of the Pearson linear coefficient. Strong positive correlations between the naturally occurring radionuclides, and also among Pb, Zn, Cu and Cd were found.
Guerrero, Erick G.; Heslin, Kevin C.; Chang, Evelyn; Fenwick, Karissa; Yano, Elizabeth
2014-01-01
This study explored the role of organizational factors in the ability of Veterans Health Administration (VHA) clinics to implement colocated mental health care in primary care settings (PC-MH). The study used data from the VHA Clinical Practice Organizational Survey collected in 2007 from 225 clinic administrators across the United States. Clinic degree of implementation of PC-MH was the dependent variable, whereas independent variables included policies and procedures, organizational context, and leaders’ perceptions of barriers to change. Pearson bivariate correlations and multivariable linear regression were used to test hypotheses. Results show that depression care training for primary care providers and clinics’ flexibility and participation were both positively correlated with implementation of PC-MH. However, after accounting for other factors, regressions show that only training primary care providers in depression care was marginally associated with degree of implementation of PC-MH (p = 0.051). Given the importance of this topic for implementing integrated care as part of health care reform, these null findings underscore the need to improve theory and testing of more proximal measures of colocation in future work. PMID:25096986
Guerrero, Erick G; Heslin, Kevin C; Chang, Evelyn; Fenwick, Karissa; Yano, Elizabeth
2015-07-01
This study explored the role of organizational factors in the ability of Veterans Health Administration (VHA) clinics to implement colocated mental health care in primary care settings (PC-MH). The study used data from the VHA Clinical Practice Organizational Survey collected in 2007 from 225 clinic administrators across the United States. Clinic degree of implementation of PC-MH was the dependent variable, whereas independent variables included policies and procedures, organizational context, and leaders' perceptions of barriers to change. Pearson bivariate correlations and multivariable linear regression were used to test hypotheses. Results show that depression care training for primary care providers and clinics' flexibility and participation were both positively correlated with implementation of PC-MH. However, after accounting for other factors, regressions show that only training primary care providers in depression care was marginally associated with degree of implementation of PC-MH (p = 0.051). Given the importance of this topic for implementing integrated care as part of health care reform, these null findings underscore the need to improve theory and testing of more proximal measures of colocation in future work. PMID:25096986
NASA Astrophysics Data System (ADS)
Kiram, Johannah Jamalul; Sulaiman, Jumat; Swanto, Suyansah; Din, Wardatul Akmam
2014-07-01
This paper seeks to investigate the relationship between language learning strategies and proficiency in English. Fifty-six pre-university students (22 males, 34 females) of University Malaysia Sabah participated in this study. Oxford's Strategy Inventory for Language Learning (SILL) self-report questionnaire was adopted to identify the students' language learning strategies, whereas their proficiencies were judged based on their Malaysian University English Test (MUET) Results. Pearson's correlation coefficient, Spearman's rank correlation coefficient and the t-test were utilized to make statistical interpretation about the relationship. The knowledge obtained from this study will be helpful for future studies on how to improve the quality of learning and proficiency in English.
CMS results on multijet correlations
Safronov, Grigory
2015-04-10
We present recent CMS measurements on multijet correlations using forward and low-p{sub T} jets, focusing on searches for BFKL and saturation phenomena. In pp collisions at √(s)=7 TeV, azimuthal correlations in dijets separated in rapidity by up to 9.4 units were measured. The results are compared to BFKL- and DGLAP-based predictions. In pp collisions at √(s)=8 TeV, cross sections for jets with p{sub T} > 21 GeV and |y| < 4.7, and for track-jets with p{sub T} > 1 GeV (minijets) are presented. The minijet results are sensitive to the bound imposed by the total inelastic cross section, and are compared to various models for taming the growth of the 2 → 2 cross section at low p{sub T}.
Softness Correlations Across Length Scales
NASA Astrophysics Data System (ADS)
Ivancic, Robert; Shavit, Amit; Rieser, Jennifer; Schoenholz, Samuel; Cubuk, Ekin; Durian, Douglas; Liu, Andrea; Riggleman, Robert
In disordered systems, it is believed that mechanical failure begins with localized particle rearrangements. Recently, a machine learning method has been introduced to identify how likely a particle is to rearrange given its local structural environment, quantified by softness. We calculate the softness of particles in simulations of atomic Lennard-Jones mixtures, molecular Lennard-Jones oligomers, colloidal systems and granular systems. In each case, we find that the length scale characterizing spatial correlations of softness is approximately a particle diameter. These results provide a rationale for why localized rearrangements--whose size is presumably set by the scale of softness correlations--might occur in disordered systems across many length scales. Supported by DOE DE-FG02-05ER46199.
CMS results on multijet correlations
NASA Astrophysics Data System (ADS)
Safronov, Grigory
2015-04-01
We present recent CMS measurements on multijet correlations using forward and low-pT jets, focusing on searches for BFKL and saturation phenomena. In pp collisions at √{s }=7 TeV, azimuthal correlations in dijets separated in rapidity by up to 9.4 units were measured. The results are compared to BFKL- and DGLAP-based predictions. In pp collisions at √{s }=8 TeV, cross sections for jets with pT > 21 GeV and |y| < 4.7, and for track-jets with pT > 1 GeV (minijets) are presented. The minijet results are sensitive to the bound imposed by the total inelastic cross section, and are compared to various models for taming the growth of the 2 → 2 cross section at low pT.
Correlated Electrons in Reduced Dimensions
Bonesteel, Nicholas E
2015-01-31
This report summarizes the work accomplished under the support of US DOE grant # DE-FG02-97ER45639, "Correlated Electrons in Reduced Dimensions." The underlying hypothesis of the research supported by this grant has been that studying the unique behavior of correlated electrons in reduced dimensions can lead to new ways of understanding how matter can order and how it can potentially be used. The systems under study have included i) fractional quantum Hall matter, which is realized when electrons are confined to two-dimensions and placed in a strong magnetic field at low temperature, ii) one-dimensional chains of spins and exotic quasiparticle excitations of topologically ordered matter, and iii) electrons confined in effectively ``zero-dimensional" semiconductor quantum dots.
Ultraviolet divergences in cosmological correlations
Weinberg, Steven
2011-03-15
A method is developed for dealing with ultraviolet divergences in calculations of cosmological correlations, which does not depend on dimensional regularization. An extended version of the WKB approximation is used to analyze the divergences in these calculations, and these divergences are controlled by the introduction of Pauli-Villars regulator fields. This approach is illustrated in the theory of a scalar field with arbitrary self-interactions in a fixed flat-space Robertson-Walker metric with arbitrary scale factor a(t). Explicit formulas are given for the counterterms needed to cancel all dependence on the regulator properties, and an explicit prescription is given for calculating finite regulator-independent correlation functions. The possibility of infrared divergences in this theory is briefly considered.
Bootstrapping N=2 chiral correlators
NASA Astrophysics Data System (ADS)
Lemos, Madalena; Liendo, Pedro
2016-01-01
We apply the numerical bootstrap program to chiral operators in four-dimensional N=2 SCFTs. In the first part of this work we study four-point functions in which all fields have the same conformal dimension. We give special emphasis to bootstrapping a specific theory: the simplest Argyres-Douglas fixed point with no flavor symmetry. In the second part we generalize our setup and consider correlators of fields with unequal dimension. This is an example of a mixed correlator and allows us to probe new regions in the parameter space of N=2 SCFTs. In particular, our results put constraints on relations in the Coulomb branch chiral ring and on the curvature of the Zamolodchikov metric.
Xu, Xiao Quan; Choi, Young Jun; Sung, Yu Sub; Yoon, Ra Gyoung; Jang, Seung Won; Park, Ji Eun; Heo, Young Jin; Baek, Jung Hwan
2016-01-01
Objective To investigate the correlation between perfusion- and diffusion-related parameters from intravoxel incoherent motion (IVIM) and those from dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted imaging in tumors and normal muscles of the head and neck. Materials and Methods We retrospectively enrolled 20 consecutive patients with head and neck tumors with MR imaging performed using a 3T MR scanner. Tissue diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were derived from bi-exponential fitting of IVIM data obtained with 14 different b-values in three orthogonal directions. We investigated the correlation between D, f, and D* and model-free parameters from the DCE-MRI (wash-in, Tmax, Emax, initial AUC60, whole AUC) and the apparent diffusion coefficient (ADC) value in the tumor and normal masseter muscle using a whole volume-of-interest approach. Pearson's correlation test was used for statistical analysis. Results No correlation was found between f or D* and any of the parameters from the DCE-MRI in all patients or in patients with squamous cell carcinoma (p > 0.05). The ADC was significantly correlated with D values in the tumors (p < 0.001, r = 0.980) and muscles (p = 0.013, r = 0.542), despite its significantly higher value than D. The difference between ADC and D showed significant correlation with f values in the tumors (p = 0.017, r = 0.528) and muscles (p = 0.003, r = 0.630), but no correlation with D* (p > 0.05, respectively). Conclusion Intravoxel incoherent motion shows no significant correlation with model-free perfusion parameters derived from the DCE-MRI but is feasible for the analysis of diffusivity in both tumors and normal muscles of the head and neck. PMID:27587952
Electron correlation energies in atoms
NASA Astrophysics Data System (ADS)
McCarthy, Shane Patrick
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.
Neural correlates and causal mechanisms.
Hohwy, Jakob
2012-06-01
What Joseph Neisser calls for is exactly right: more philosophy of science will help us better understand and refine the idea of neural correlates of consciousness (NCC). But (i) the key bit of philosophy of science Neisser appeals to is itself in need of clarification; (ii) the orthodox NCC definition is more resourceful than Neisser allows, and (iii) it is possible to resist the phenomenological conception of conscious experience that fuels some of Neisser's argument.
Petrovic, Bojan D; Nikolaidis, Paul; Hammond, Nancy A; Martin, John A; Petrovic, Polina V; Desai, Pankaja M; Miller, Frank H
2007-12-01
Primary sclerosing cholangitis is a chronic, progressive disease of inflammation and fibrosis of the bile ducts. The ability to predict survival is important for appropriate management and treatment decisions. The purpose of this study was to examine the relationship between specific findings on the enhanced magnetic resonance imaging (MRI) examination of the liver and the corresponding magnetic resonance cholangiopancreatogram (MRCP) and a survival model for primary sclerosing cholangitis (PSC), the Mayo Risk Score. During a five-year period, 47 patients with primary sclerosing cholangitis were identified who had a complete MRI/MRCP examination. The extent of anatomical changes of the biliary tree and the degree of peribiliary enhancement in the hepatic parenchyma were compared with the Mayo Risk Score for each patient. Peribiliary enhancement was present to a varying extent in 38 of 47 cases of PSC. Peribiliary enhancement 3 min after gadolinium administration had a weak correlation with the Mayo Risk Score (analysis of variance P<0.01, Pearson correlation r=0.37). No statistically significant relationship between the severity of extrahepatic or intrahepatic duct changes and the Mayo Risk Score was found (analysis of variance P=0.24, P=0.38, respectively). Although biliary tree changes on MRCP aid in the diagnosis of PSC, they do not correlate with survival, as predicted by the Mayo Risk Score. Peribiliary enhancement on MRI of the liver is a finding occurring to a variable extent in primary sclerosing cholangitis but does not correlate significantly with survival.
Miller, J M; Ashton-Miller, J A; Carchidi, L T; DeLancey, J O
1999-03-01
This study examined the association between the measured amount of urine lost during a standardized series of coughs in clinic (paper towel test) and questionnaire estimates of stress-related urine loss in 51 older women with mild to moderate urinary incontinence. It also examined the relationship between these questionnaire estimates and a 6-day urinary diary self-report of incontinence frequency and voiding episodes. Pearson's correlation coefficient and percent agreement were used to analyze the relationship between the variables. No significant correlations were found between the paper towel test results and questionnaire items reporting volume of urine loss. The relationship between urinary diary results and questionnaire items regarding the number of incontinence occurrences was weak but significant (r = 0.33, p = 0.045), with agreement in 53% of cases. Agreement was achieved in 68% of cases for number of voids per day recorded by urinary diary and reported by questionnaire (r = 0.65, p = 0.000). This study has quantified a weak correlation between objective and subjective measures of urine loss. These weak correlations could arise from either methodologic limitations in quantifying incontinence or the degree to which differences arise because different phenomena are being measured. PMID:10100129
Wada, Osamu; Tateuchi, Hiroshige; Ichihashi, Noriaki
2014-01-01
Body rotation is associated with many activities. The concomitant movement of the center of mass (COM) is essential for effective body rotation. This movement is considered to be influenced by kinematic changes in the spine, pelvis, and hip joints. However, there is no research on the association between COM movement and kinematic changes during body rotation. We aimed to investigate the association between COM movement and the kinematics of the spine, pelvis, and hip joints during body rotation in standing. Twenty-four healthy men were included in the study. COM movement during active body rotation in a standing position was measured. We evaluated pelvic shift and changes in the angles of the spine, pelvis, and hip joints. We calculated the Pearson correlation coefficients to analyze the relationship between COM movement and kinematic changes in the spine, pelvis, and hip joints. There were significant correlations between lateral COM movement to the rotational side and pelvic shift to the rotational side, and between posterior COM movement and pelvic shift to the posterior side. In addition, lateral COM movement to the rotational side showed significant and negative correlation with spinal flexion and was significantly and positively correlated with the change in anterior pelvic tilt. Clinicians need to take particular note of both spinal and pelvic motion in the sagittal plane, as well as the pelvic shift, to speculate COM movement during body rotation in standing.
Salaffi, Fausto; Carotti, Marina; Bosello, Silvia; Bichisecchi, Elisabetta; Giuseppetti, Gianmarco; Ferraccioli, Gianfranco
2015-01-01
Objective. To evaluate the performance of a computerized-aided method (CaM) for quantification of interstitial lung disease (ILD) in patients with systemic sclerosis and to determine its correlation with the conventional visual reader-based score (CoVR) and the pulmonary function tests (PFTs). Methods. Seventy-nine patients were enrolled. All patients underwent chest high resolution computed tomography (HRCT) scored by two radiologists adopting the CoVR. All HRCT images were then analysed by a CaM using a DICOM software. The relationships among the lung segmentation analysis, the readers, and the PFTs results were calculated using linear regression analysis and Pearson's correlation. Receiver operating curve analysis was performed for determination of CaM extent threshold. Results. A strong correlation between CaM and CoVR was observed (P < 0.0001). The CaM showed a significant negative correlation with forced vital capacity (FVC) (P < 0.0001) and the single breath carbon monoxide diffusing capacity of the lung (DLco) (P < 0.0001). A CaM optimal extent threshold of 20% represented the best compromise between sensitivity (75.6%) and specificity (97.4%). Conclusions. CaM quantification of SSc-ILD can be useful in the assessment of extent of lung disease and may provide reliable tool in daily clinical practice and clinical trials. PMID:25629053
Quantum correlations beyond Tsirelson's bound
NASA Astrophysics Data System (ADS)
Berry, Dominic; Ringbauer, Martin; Fedrizzi, Alessandro; White, Andrew
2014-03-01
Violations of Bell inequalities show that there are correlations that cannot explained by any classical theory. Further violation, beyond Tsirelson's bound, shows that there are correlations that are not explained by quantum mechanics. Such super-quantum correlations would enable violation of information causality, where communication of one bit provides more than one bit of information [Nature 461, 1101 (2009)]. An unavoidable feature of all realistic Bell inequality experiments is loss. If one postselects on successful measurements, unentangled states can violate Bell inequalities. On the other hand, loss can be used to enhance the violation of Bell inequalities for entangled states. This can improve the ability to distinguish between entangled and unentangled states, despite loss. Here we report an optical experiment providing maximal violation of the CHSH-Bell inequality with entangled states. Due to loss and postselection, Tsirelson's bound is also violated. This enables us to more easily distinguish between entangled and unentangled states. In addition, it provides violation of information causality for the postselected data.
Correlated Temporal and Spectral Variability
NASA Technical Reports Server (NTRS)
Swank, Jean H.
2007-01-01
The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.
A Correlation Study of Student Attitudes Toward Science in a Southern State High School
NASA Astrophysics Data System (ADS)
Barco-Southall, Crystal
The purpose of this correlational research study was to examine the attitudes toward science of students in Grades 11 and 12 and to investigate if there were differences resulting from gender, grade level, ethnicity, and the level of the curriculum received in average or advanced placement (AP) honors science. The participants of this study consisted of 50 randomly selected male and female high school students who were enrolled in AP and average science classes in an urban Southern state high school. The study used the Test of Science Related Attitudes (TOSRA) instrument to measure students' attitudes toward science in seven categories including (a) Social Implications of Science, (b) Normality of Scientists, (c) Attitude Toward Scientific Inquiry, (d) Adoption of Scientific Attitudes, (e) Enjoyment of Science Lessons, (f) Leisure Interest in Science, and (g) Career Interest in Science. The quantitative component of the study allowed the researcher to determine whether there were gender differences in attitudes toward science based on the seven subscales and measuring different aspects of science attitudes. Statistical treatment of the TOSRA survey involved the use of descriptive statistics, Pearson correlation, and multiple and linear regression. Findings did not reveal significant gender differences on the total attitude scores although there were differences on several of the subscales. In addition, there were no significant differences in the mean attitude scores for grade level. However, the study did reveal differences in ethnicity and attitudes toward science. With regard to ethnicity, scores for Native Americans and Whites were higher than scores for Asians, African Americans, and Hispanics indicating that Native Americans and White students showed a more positive attitude toward science. Regarding the level of curriculum received by students who were exposed to advanced level science courses showed more positive attitudes toward science than those students
NASA Astrophysics Data System (ADS)
Reddick, Wilburn E.; Glass, John O.; Shan, Zuyao Y.; Wu, Shengjie; Helton, Susan; Mulhern, Raymond K.
2005-04-01
Due to the inherent risk of central nervous system (CNS) dissemination, children treated for either acute lymphoblastic leukemia (ALL) or malignant brain tumors (BT) receive aggressive CNS therapy. The primary objective of this study was to confirm a previously observed association between reduced volumes of normal-appearing white matter (NAWM) and intellectual and attentional deficits in survivors. A combined MR imaging set consisting of T1, T2, and PD images were collected for 221 children (110 BT; 112 ALL). MR imaging sets were segmented with a hybrid neural network algorithm and volumetric measurements were calculated for five slices centered on the basal ganglia. Summary measures of Overall Index, Omissions, d" (attentiveness), and beta (risk-taking) were derived from the computer-administered Conners" Continuous Performance Test (CPT). Age-corrected estimates of Full-Scale IQ (FSIQ) were also obtained. Pearson correlation analyses were performed between each neurocognitive measure and the volume of NAWM. The correlation between FSIQ and NAWM failed to reach statistical significance for the BT group but was highly significant for the more homogeneous ALL group. Larger Omission rates, decreased attentiveness and more risk taking were significantly associated with lower NAWM volumes in both groups of survivors. Long-term survivors are at increased risk for cognitive delays or deficits, which oftentimes impair future academic performance, employment, and quality of life. These long-term adverse effects of treatment appear to be due to a diminished ability to acquire new information and may be secondary to deficits in attention, which is thought to be supported by interhemispheric and intrahemispheric white matter tracts.
PREFACE: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Saxena, Siddharth S.; Littlewood, P. B.
2012-07-01
This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to 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
Bae, Won C; Chen, Peter C; Chung, Christine B; Masuda, Koichi; D'Lima, Darryl; Du, Jiang
2012-04-01
In this study we describe the use of ultrashort echo time (UTE) magnetic resonance imaging (MRI) to evaluate short and long T2* components as well as the water content of cortical bone. Fourteen human cadaveric distal femur and proximal tibia were sectioned to produce 44 rectangular slabs of cortical bone for quantitative UTE MR imaging, microcomputed tomography (µCT), and biomechanical testing. A two-dimensional (2D) UTE pulse sequence with a minimal nominal TE of 8 µseconds was used together with bicomponent analysis to quantify the bound and free water in cortical bone using a clinical 3T scanner. Total water concentration was measured using a 3D UTE sequence together with a reference water phantom. UTE MR measures of water content (total, free, and bound), T2* (short and long), and short and long T2* fractions were compared with porosity assessed with µCT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation. Porosity significantly correlated positively with total (R(2) = 0.23; p < 0.01) and free (R(2) = 0.31; p < 0.001) water content as well as long T2* fraction (R(2) = 0.25; p < 0.001), and negatively with short T2* fraction and short T2* (R(2) = 0.24; p < 0.01). Failure strain significantly correlated positively with short T2* (R(2) = 0.29; p < 0.001), ultimate stress significantly correlated negatively with total (R(2) = 0.25; p < 0.001) and bound (R(2) = 0.22; p < 0.01) water content, and failure energy significantly correlated positively with both short (R(2) = 0 30; p < 0.001) and long (R(2) = 0.17; p < 0.01) T2* values. These results suggest that UTE MR measures are sensitive to the structure and failure properties of human cortical bone, and may provide a novel way of evaluating cortical bone quality.
2013-01-01
Background Epithelial ovarian cancer (EOC) is one of the most lethal gynecological cancers; the majority of EOC is the serous histotype and diagnosed at advanced stage. IL6 is the cytokine that has been found most frequently associated with carcinogenesis and progression of serous EOCs. IL6 is a growth-promoting and anti-apoptotic factor, and high plasma levels of IL6 in advanced stage EOCs correlate with poor prognosis. The objective of the present study was to identify IL6 co-regulated genes and gene network/s in EOCs. Results We applied bioinformatics tools on 7 publicly available data sets containing the gene expression profiles of 1262 EOC samples. By Pearson's correlation analysis we identified, in EOCs, an IL6-correlated gene signature containing 40 genes mainly associated with proliferation. 33 of 40 genes were also significantly correlated in low malignant potential (LMP) EOCs, while 7 genes, named C5AR1, FPR1, G0S2, IL8, KLF2, MMP19, and THBD were IL6-correlated only in advanced stage EOCs. Among the 40-gene signature EGFR ligand HBEGF, genes of the EGR family members and genes encoding for negative feedback regulators of growth factor signaling were included. The results obtained by Gene Set Enrichment and Ingenuity Pathway Analyses enabled the identification, respectively, of gene sets associated with ‘early growth factor response’ for the 40-gene signature, and a biological network related to ‘thrombosis and cardiovascular disease’ for the 7-gene signature. In agreement with these results, selected genes from the identified signatures were validated in vitro by real time RT-PCR in serous EOC cell lines upon stimulation with EGF. Conclusions Serous EOCs, independently of their aggressiveness, co-regulate IL6 expression together with that of genes associated to growth factor signaling, arguing for the hypothesis that common mechanism/s driven by EGFR ligands characterize both advanced-stage and LMP EOCs. Only advanced-stage EOCs appeared to be
Shear wave elastography results correlate with liver fibrosis histology and liver function reserve
Feng, Yan-Hong; Hu, Xiang-Dong; Zhai, Lin; Liu, Ji-Bin; Qiu, Lan-Yan; Zu, Yuan; Liang, Si; Gui, Yu; Qian, Lin-Xue
2016-01-01
AIM: To evaluate the correlation of shear wave elastography (SWE) results with liver fibrosis histology and quantitative function reserve. METHODS: Weekly subcutaneous injection of 60% carbon tetrachloride (1.5 mL/kg) was given to 12 canines for 24 wk to induce experimental liver fibrosis, with olive oil given to 2 control canines. At 24 wk, liver condition was evaluated using clinical biochemistry assays, SWE imaging, lidocaine metabolite monoethylglycine-xylidide (MEGX) test, and histologic fibrosis grading. Clinical biochemistry assays were performed at the institutional central laboratory for routine liver function evaluation. Liver stiffness was measured in triplicate from three different intercostal spaces and expressed as mean liver stiffness modulus (LSM). Plasma concentrations of lidocaine and its metabolite MEGX were determined using high-performance liquid chromatography repeated in duplicate. Liver biopsy samples were fixed in 10% formaldehyde, and liver fibrosis was graded using the modified histological activity index Knodell score (F0-F4). Correlations among histologic grading, LSM, and MEGX measures were analyzed with the Pearson linear correlation coefficient. RESULTS: At 24 wk liver fibrosis histologic grading was as follows: F0, n = 2 (control); F1, n = 0; F2, n = 3; F3, n = 7; and F4, n = 2. SWE LSM was positively correlated with histologic grading (r = 0.835, P < 0.001). Specifically, the F4 group had a significantly higher elastic modulus than the F3, F2, and F0 groups (P = 0.002, P = 0.003, and P = 0.006, respectively), and the F3 group also had a significantly higher modulus than the control F0 group (P = 0.039). LSM was negatively associated with plasma MEGX concentrations at 30 min (r = -0.642; P = 0.013) and 60 min (r = -0.651; P = 0.012), time to ½ of the maximum concentration (r = -0.538; P = 0.047), and the area under the curve (r = -0.636; P = 0.014). Multiple comparisons showed identical differences in these three measures
NASA Technical Reports Server (NTRS)
Johnson, R. A.; Wehrly, T.
1976-01-01
Population models for dependence between two angular measurements and for dependence between an angular and a linear observation are proposed. The method of canonical correlations first leads to new population and sample measures of dependence in this latter situation. An example relating wind direction to the level of a pollutant is given. Next, applied to pairs of angular measurements, the method yields previously proposed sample measures in some special cases and a new sample measure in general.
Vocal dose in teachers: correlation with dysphonia.
Gama, Ana Cristina Côrtes; Santos, Juliana Nunes; Pedra, Elisângela de Fátima Pereira; Rabelo, Alessandra Terra Vasconcelos; Magalhães, Max de Castro; Casas, Estevam Barbosa de Las
2016-04-01
Teachers are professionals with high prevalence of dysphonia, whose main risk factors are the large work hours in classrooms with the presence of background noise. The purpose of the study was to calculate the phonation time and the cycle dose of teachers with dysphonia and teachers without voice disorders during the class. There were two groups analyzed: five teachers with functional dysphonia were the first group and five teachers without voice disorders were the second group. For the data was used the VoxLog® dosimeter and the parameters were: intensity; fundamental frequency; phonation time and cycle dose. The statistical analysis used ANOVA, Student's T-test, and Kruskal-Wallis test. Dysphonic teachers showed major values of phonation time and cycle dose compared with teachers without voice disorders. The dysphonia is related to extended period of speech time and greater exposure of the tissue of the vocal fold to phonotrauma. PMID:27191884
Correlation, functional analysis and optical pattern recognition
Dickey, F.M.; Lee, M.L.; Stalker, K.T.
1994-03-01
Correlation integrals have played a central role in optical pattern recognition. The success of correlation, however, has been limited. What is needed is a mathematical operation more complex than correlation. Suitably complex operations are the functionals defined on the Hilbert space of Lebesgue square integrable functions. Correlation is a linear functional of a parameter. In this paper, we develop a representation of functionals in terms of inner products or equivalently correlation functions. We also discuss the role of functionals in neutral networks. Having established a broad relation of correlation to pattern recognition, we discuss the computation of correlation functions using acousto-optics.
Iterative method for generating correlated binary sequences
NASA Astrophysics Data System (ADS)
Usatenko, O. V.; Melnik, S. S.; Apostolov, S. S.; Makarov, N. M.; Krokhin, A. A.
2014-11-01
We propose an efficient iterative method for generating random correlated binary sequences with a prescribed correlation function. The method is based on consecutive linear modulations of an initially uncorrelated sequence into a correlated one. Each step of modulation increases the correlations until the desired level has been reached. The robustness and efficiency of the proposed algorithm are tested by generating sequences with inverse power-law correlations. The substantial increase in the strength of correlation in the iterative method with respect to single-step filtering generation is shown for all studied correlation functions. Our results can be used for design of disordered superlattices, waveguides, and surfaces with selective transport properties.
Wang, Yuming; Liang, Shuying; Yu, Erman; Guo, Jinling; Li, Zizhao; Wang, Zhe; Du, Yukai
2011-10-01
CD4 count is the standard method for determining eligibility for highly active antiretroviral therapy (HAART) and monitoring HIV/AIDS disease progression, but it is not widely available in resource-limited settings. This study examined the correlation between total lymphocyte count (TLC) and CD4 count of HIV-infected patients before and after HAART, and assessed the thresholds of TLC for making decisions about the initiation and for monitoring HAART. A retrospective study was performed, and 665 HIV-infected patients with TLC and CD4 count from four counties (Shangcai, Queshan, Shenqiu and Weishi) were included in the study. Pearson correlation and receiver operating characteristic (ROC) were used. TLC and CD4 count after HAART was significantly increased as compared with pre-HAART (P<0.01). An overall positive correlation was noted between TLC and CD4 count (pre-HAART, r=0.73, P=0.0001; follow-up HAART, r=0.56, P=0.0001). The ROC curve between TLC and CD4 count showed that TLC ≤ 1200 cells/mm(3) could predict CD4 < 200 cells/mm(3) with a sensitivity of 71.12%, specificity of 66.35% at pre-HAART. After 12-month HAART, the optimum prediction for CD4 count < 200 cells/mm3 was a TLC ≤ 1300 cells/mm(3), with a sensitivity of 63.27%, and a specificity of 74.84%. Further finding indicated that TLC change was positively correlated to CD4 change (r=0.77, P=0.0001) at the time point of 12-month treatment, and the best prediction point of TLC change for CD4 increasing was 135 cells/mm(3). TLC and its change can be used as a surrogate marker for CD4 count and its change of HIV-infected individuals for making decisions about the initiation and for monitoring HAART in resource-limited settings.
Palko, Joel R.; Iwabe, Simone; Pan, Xueliang; Agarwal, Gunjan; Komáromy, András M.; Liu, Jun
2013-01-01
Purpose. We examined the biomechanical properties and correlation with the collagen solubility profile of the posterior sclera in a canine model of primary open-angle glaucoma caused by the G661R missense mutation in the ADAMTS10 gene. Methods. Scleral strips from ADAMTS10-mutant (affected) dogs and age-matched controls were collected. Viscoelastic properties (i.e., complex modulus and tan[δ]) were measured using dynamic mechanical analysis (DMA) with a 0.15% sinusoidal strain at different frequencies superimposed upon different preloads. A tensile ramp was performed following DMA. The collagen solubility profile was examined using a colorimetric hydroxyproline assay to determine the amount of soluble and insoluble collagen. The viscoelastic properties were compared between groups using linear mixed models for repeated measures at different preloads and frequencies. The correlation between the biomechanical properties and collagen content were evaluated using Pearson correlations. Results. Complex modulus and tan(δ) were significantly lower in the affected group (P < 0.001), and the differences were consistent at different preloads and frequencies. The B value from the tensile ramp test also was significantly lower in the affected group (P = 0.02). The insoluble collagen was significantly lower in the affected group (P < 0.05) and correlated positively with the complex modulus (R = 0.88, P < 0.005). Conclusions. An inherently weaker and biochemically distinct posterior sclera was observed in dogs with the G661R missense mutation in ADAMTS10 before clinical indications of optic nerve damage. It remains to be shown whether and how the altered scleral biomechanics may affect the rate of glaucoma progression following intraocular pressure elevation. PMID:23518772
Sopher, Aviva B.; Gerken, Adrienne T.; Lee, Eun-Ju; Blaner, William E.; Deeds, Stefanie; Gallagher, Dympna; Shungu, Dikoma C.; Mao, Xiangling; Hassoun, Abeer; McMahon, Donald J.; Oberfield, Sharon E.
2013-01-01
Background Retinol-binding protein 4 (RBP4) has been proposed as an early marker for insulin resistance (IR), but no prior studies have addressed RBP4 in an exclusively prepubertal population. Children with premature adrenarche (PA) are at increased risk for IR and metabolic syndrome (MeS), thus finding an appropriate early marker for IR in this population would allow for early intervention and prevention of morbidity related to IR and MeS. Objective To determine whether prepubertal children with PA have higher levels of RBP4 than controls and whether RBP4 correlates with comorbidities of metabolic disease in prepubertal children. Subjects This study comprised 49 prepubertal children (24 with PA and 25 control subjects), 20 boys and 29 girls, who were between the ages of 5 and 9 years. Methods This was a cross-sectional, case-control study conducted in a subspecialty ambulatory clinic based in a quaternary care center. RBP4 levels, hormonal values, lipids and response to an oral glucose tolerance test were evaluated in children with PA and controls, and body composition measures were obtained in a subset of patients (n=18). Results RBP4 correlated with triglycerides (r = 0.57, P < 0.0001) but did not correlate with IR in a body mass index z-score-adjusted Pearson correlation analysis. There was no difference in RBP4 levels between the PA and control groups. Conclusions These findings suggest that RBP4 may be an early marker of dyslipidemia, which may herald future onset of hepatic IR, polycystic ovary syndrome and MeS. PMID:22145457
Variable Selection through Correlation Sifting
NASA Astrophysics Data System (ADS)
Huang, Jim C.; Jojic, Nebojsa
Many applications of computational biology require a variable selection procedure to sift through a large number of input variables and select some smaller number that influence a target variable of interest. For example, in virology, only some small number of viral protein fragments influence the nature of the immune response during viral infection. Due to the large number of variables to be considered, a brute-force search for the subset of variables is in general intractable. To approximate this, methods based on ℓ1-regularized linear regression have been proposed and have been found to be particularly successful. It is well understood however that such methods fail to choose the correct subset of variables if these are highly correlated with other "decoy" variables. We present a method for sifting through sets of highly correlated variables which leads to higher accuracy in selecting the correct variables. The main innovation is a filtering step that reduces correlations among variables to be selected, making the ℓ1-regularization effective for datasets on which many methods for variable selection fail. The filtering step changes both the values of the predictor variables and output values by projections onto components obtained through a computationally-inexpensive principal components analysis. In this paper we demonstrate the usefulness of our method on synthetic datasets and on novel applications in virology. These include HIV viral load analysis based on patients' HIV sequences and immune types, as well as the analysis of seasonal variation in influenza death rates based on the regions of the influenza genome that undergo diversifying selection in the previous season.
The crystallography of correlated disorder
NASA Astrophysics Data System (ADS)
Keen, David A.; Goodwin, Andrew L.
2015-05-01
Classical crystallography can determine structures as complicated as multi-component ribosomal assemblies with atomic resolution, but is inadequate for disordered systems--even those as simple as water ice--that occupy the complex middle ground between liquid-like randomness and crystalline periodic order. Correlated disorder nevertheless has clear crystallographic signatures that map to the type of disorder, irrespective of the underlying physical or chemical interactions and material involved. This mapping hints at a common language for disordered states that will help us to understand, control and exploit the disorder responsible for many interesting physical properties.
Speeding up local correlation methods
Kats, Daniel
2014-12-28
We present two techniques that can substantially speed up the local correlation methods. The first one allows one to avoid the expensive transformation of the electron-repulsion integrals from atomic orbitals to virtual space. The second one introduces an algorithm for the residual equations in the local perturbative treatment that, in contrast to the standard scheme, does not require holding the amplitudes or residuals in memory. It is shown that even an interpreter-based implementation of the proposed algorithm in the context of local MP2 method is faster and requires less memory than the highly optimized variants of conventional algorithms.
Boundary anomalies and correlation functions
NASA Astrophysics Data System (ADS)
Huang, Kuo-Wei
2016-08-01
It was shown recently that boundary terms of conformal anomalies recover the universal contribution to the entanglement entropy and also play an important role in the boundary monotonicity theorem of odd-dimensional quantum field theories. Motivated by these results, we investigate relationships between boundary anomalies and the stress tensor correlation functions in conformal field theories. In particular, we focus on how the conformal Ward identity and the renormalization group equation are modified by boundary central charges. Renormalized stress tensors induced by boundary Weyl invariants are also discussed, with examples in spherical and cylindrical geometries.
Correlation dimension of complex networks.
Lacasa, Lucas; Gómez-Gardeñes, Jesús
2013-04-19
We propose a new measure to characterize the dimension of complex networks based on the ergodic theory of dynamical systems. This measure is derived from the correlation sum of a trajectory generated by a random walker navigating the network, and extends the classical Grassberger-Procaccia algorithm to the context of complex networks. The method is validated with reliable results for both synthetic networks and real-world networks such as the world air-transportation network or urban networks, and provides a computationally fast way for estimating the dimensionality of networks which only relies on the local information provided by the walkers.
The crystallography of correlated disorder.
Keen, David A; Goodwin, Andrew L
2015-05-21
Classical crystallography can determine structures as complicated as multi-component ribosomal assemblies with atomic resolution, but is inadequate for disordered systems--even those as simple as water ice--that occupy the complex middle ground between liquid-like randomness and crystalline periodic order. Correlated disorder nevertheless has clear crystallographic signatures that map to the type of disorder, irrespective of the underlying physical or chemical interactions and material involved. This mapping hints at a common language for disordered states that will help us to understand, control and exploit the disorder responsible for many interesting physical properties.
Pairing Correlations at High Spins
NASA Astrophysics Data System (ADS)
Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.
The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.
Preselected Sub-Poissonian Correlations
NASA Technical Reports Server (NTRS)
Pavicic, Mladen
1996-01-01
The simplest possible photon-number-squeezed states containing only two photons and exhibiting sub-poissonian statistics with the Fano factor approaching 0.5 have been used for a proposal of a loophole-free Bell experiment requiring only 67 percent of detection efficiency. The states are obtained by the fourth order interference first of two downconverted photons at an asymmetrical beam splitter and thereupon of two photons from two independent singlets at an asymmetrical beam splitter. In the latter set-up, the other two photons which nowhere interacted and whose paths never crossed appear entangled in a singlet-like correlated state.
EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Ronning, Filip; Batista, Cristian
2011-03-01
Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 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
Novelty filtered optical correlator using photorefractive crystal
NASA Technical Reports Server (NTRS)
Liu, Duncan T. H.; Chao, Tien-Hsin; Cheng, Li-Jen
1992-01-01
We demonstrate a new optical correlator in which the correlation peak intensity is increased when the matched input object is moving. The basic configuration of the correlator is the same as a VanderLugt optical correlator consisting of a photorefractive crystal. The principal of this new correlator is based on the dynamic grating erasure property of photorefractive materials. The detail of this principle is described.
Sathananthan, Gnalini; Aggarwal, Gunjan; Zahid, Simmi; Byth, Karen; Chik, William; Friedman, Daniel; Thiagalingam, Aravinda
2015-05-01
The cardiac axis in a structurally normal heart is influenced by a number of factors. We investigated the anatomical and electrical cardiac axes in middle-aged individuals without structural heart disease and compared this with age-matched obese and older individuals without structural heart disease. A retrospective study of controls included those between 30 and 60 years old with a normal body mass index (BMI), who were then compared with obese individuals between 30 and 60 years old and with individuals more than 60 years old with a normal BMI. The anatomical cardiac axis was determined along the long axis by cardiac computed tomography (CT) and correlated with the electrical cardiac axis on a surface electrocardiogram (ECG) in the frontal plane. A total of 124 patients were included. In the controls (n = 59), the mean CT axis was 38.1° ± 7.8° whilst the mean ECG axis was 51.8° ± 26.6°, Pearson r value 0.12 (P = 0.365). In the obese (n = 36), the mean CT axis was 25.1° ± 6.2° whilst the mean ECG axis was 20.1° ± 23.9°, Pearson r value 0.05 (P = 0.808). In the older group (n = 29), the mean CT axis was 34.4° ± 9.1° whilst the mean ECG axis was 34.4° ± 30.3°, Pearson r value 0.26 (P = 0.209). Obese individuals have a more leftward rotation of both axes than age-matched normals (P <0.0001), which could be secondary to elevation of the diaphragm. Older individuals have a more leftward rotation only of their electrical cardiac axis (P = 0.01), which could be a normal variant or reflect underlying conduction disturbances in this age group.
NASA Technical Reports Server (NTRS)
Pasham, Dheeraj R.; Strohmayer, Tod E.
2013-01-01
Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.
ASTROCHEMICAL CORRELATIONS IN MOLECULAR CLOUDS
Gaches, Brandt A. L.; Offner, Stella S. R.; Rosolowsky, Erik W.; Bisbas, Thomas G. E-mail: soffner@astro.umass.edu E-mail: tb@star.ucl.ac.uk
2015-02-01
We investigate the spectral correlations between different species used to observe molecular clouds. We use hydrodynamic simulations and a full chemical network to study the abundances of over 150 species in typical Milky Way molecular clouds. We perform synthetic observations in order to produce emission maps of a subset of these tracers. We study the effects of different lines of sight and spatial resolution on the emission distribution and perform a robust quantitative comparison of the species to each other. We use the Spectral Correlation Function (SCF), which quantifies the root mean squared difference between spectra separated by some length scale, to characterize the structure of the simulated cloud in position-position-velocity (PPV) space. We predict the observed SCF for a broad range of observational tracers, and thus identify homologous species. In particular, we show that the pairs C and CO, C{sup +} and CN, and NH{sub 3} and H{sub 2}CS have very similar SCFs. We measure the SCF slope variation as a function of beam size for all species and demonstrate that the beam size has a distinct effect on different species emission. However, for beams of up to 10'', placing the cloud at 1 kpc, the change is not large enough to move the SCF slopes into different regions of parameter space. The results from this study provide observational guidance for choosing the best tracer to probe various cloud length scales.
The dynamics of correlated novelties
NASA Astrophysics Data System (ADS)
Tria, F.; Loreto, V.; Servedio, V. D. P.; Strogatz, S. H.
2014-07-01
Novelties are a familiar part of daily life. They are also fundamental to the evolution of biological systems, human society, and technology. By opening new possibilities, one novelty can pave the way for others in a process that Kauffman has called ``expanding the adjacent possible''. The dynamics of correlated novelties, however, have yet to be quantified empirically or modeled mathematically. Here we propose a simple mathematical model that mimics the process of exploring a physical, biological, or conceptual space that enlarges whenever a novelty occurs. The model, a generalization of Polya's urn, predicts statistical laws for the rate at which novelties happen (Heaps' law) and for the probability distribution on the space explored (Zipf's law), as well as signatures of the process by which one novelty sets the stage for another. We test these predictions on four data sets of human activity: the edit events of Wikipedia pages, the emergence of tags in annotation systems, the sequence of words in texts, and listening to new songs in online music catalogues. By quantifying the dynamics of correlated novelties, our results provide a starting point for a deeper understanding of the adjacent possible and its role in biological, cultural, and technological evolution.
Strongly correlated perovskite fuel cells
NASA Astrophysics Data System (ADS)
Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D.; Ramanathan, Shriram
2016-06-01
Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.
The dynamics of correlated novelties.
Tria, F; Loreto, V; Servedio, V D P; Strogatz, S H
2014-01-01
Novelties are a familiar part of daily life. They are also fundamental to the evolution of biological systems, human society, and technology. By opening new possibilities, one novelty can pave the way for others in a process that Kauffman has called "expanding the adjacent possible". The dynamics of correlated novelties, however, have yet to be quantified empirically or modeled mathematically. Here we propose a simple mathematical model that mimics the process of exploring a physical, biological, or conceptual space that enlarges whenever a novelty occurs. The model, a generalization of Polya's urn, predicts statistical laws for the rate at which novelties happen (Heaps' law) and for the probability distribution on the space explored (Zipf's law), as well as signatures of the process by which one novelty sets the stage for another. We test these predictions on four data sets of human activity: the edit events of Wikipedia pages, the emergence of tags in annotation systems, the sequence of words in texts, and listening to new songs in online music catalogues. By quantifying the dynamics of correlated novelties, our results provide a starting point for a deeper understanding of the adjacent possible and its role in biological, cultural, and technological evolution. PMID:25080941
Strongly correlated perovskite fuel cells.
Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D; Ramanathan, Shriram
2016-05-16
Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations.
Strongly correlated perovskite fuel cells.
Zhou, You; Guan, Xiaofei; Zhou, Hua; Ramadoss, Koushik; Adam, Suhare; Liu, Huajun; Lee, Sungsik; Shi, Jian; Tsuchiya, Masaru; Fong, Dillon D; Ramanathan, Shriram
2016-06-01
Fuel cells convert chemical energy directly into electrical energy with high efficiencies and environmental benefits, as compared with traditional heat engines. Yttria-stabilized zirconia is perhaps the material with the most potential as an electrolyte in solid oxide fuel cells (SOFCs), owing to its stability and near-unity ionic transference number. Although there exist materials with superior ionic conductivity, they are often limited by their ability to suppress electronic leakage when exposed to the reducing environment at the fuel interface. Such electronic leakage reduces fuel cell power output and the associated chemo-mechanical stresses can also lead to catastrophic fracture of electrolyte membranes. Here we depart from traditional electrolyte design that relies on cation substitution to sustain ionic conduction. Instead, we use a perovskite nickelate as an electrolyte with high initial ionic and electronic conductivity. Since many such oxides are also correlated electron systems, we can suppress the electronic conduction through a filling-controlled Mott transition induced by spontaneous hydrogen incorporation. Using such a nickelate as the electrolyte in free-standing membrane geometry, we demonstrate a low-temperature micro-fabricated SOFC with high performance. The ionic conductivity of the nickelate perovskite is comparable to the best-performing solid electrolytes in the same temperature range, with a very low activation energy. The results present a design strategy for high-performance materials exhibiting emergent properties arising from strong electron correlations. PMID:27279218
Dipolar correlations in liquid water
Zhang, Cui; Galli, Giulia
2014-08-28
We present an analysis of the dipolar correlations in water as a function of temperature and density and in the presence of simple ionic solutes, carried out using molecular dynamics simulations and empirical potentials. We show that the dipole-dipole correlation function of the liquid exhibits sizable oscillations over nanodomains of about 1.5 nm radius, with several isosbestic points as a function of temperature; the size of the nanodomains is nearly independent on temperature and density, between 240 and 400 K and 0.9 and 1.3 g/cm{sup 3}, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (τ) of the system dipole moment varies by a factor of about 30 and 1.5, as a function of temperature and density, respectively. At 300 K, we observed a maximum in τ as a function of density, and a corresponding shallow maximum in the tetrahedral order parameter, in a range where the diffusion coefficient, the pressure and the dielectric constant increase monotonically.
EEG, temporal correlations, and avalanches.
Benayoun, Marc; Kohrman, Michael; Cowan, Jack; van Drongelen, Wim
2010-12-01
Epileptiform activity in the EEG is frequently characterized by rhythmic, correlated patterns or synchronized bursts. Long-range temporal correlations (LRTC) are described by power law scaling of the autocorrelation function and have been observed in scalp and intracranial EEG recordings. Synchronous large-amplitude bursts (also called neuronal avalanches) have been observed in local field potentials both in vitro and in vivo. This article explores the presence of neuronal avalanches in scalp and intracranial EEG in the context of LRTC. Results indicate that both scalp and intracranial EEG show LRTC, with larger scaling exponents in scalp recordings than intracranial. A subset of analyzed recordings also show avalanche behavior, indicating that avalanches may be associated with LRTC. Artificial test signals reveal a linear relationship between the scaling exponent measured by detrended fluctuation analysis and the exponent of the avalanche size distribution. Analysis and evaluation of simulated data reveal that preprocessing of EEG (squaring the signal or applying a filter) affect the ability of detrended fluctuation analysis to reliably measure LRTC.
A correlated nickelate synaptic transistor.
Shi, Jian; Ha, Sieu D; Zhou, You; Schoofs, Frank; Ramanathan, Shriram
2013-01-01
Inspired by biological neural systems, neuromorphic devices may open up new computing paradigms to explore cognition, learning and limits of parallel computation. Here we report the demonstration of a synaptic transistor with SmNiO₃, a correlated electron system with insulator-metal transition temperature at 130°C in bulk form. Non-volatile resistance and synaptic multilevel analogue states are demonstrated by control over composition in ionic liquid-gated devices on silicon platforms. The extent of the resistance modulation can be dramatically controlled by the film microstructure. By simulating the time difference between postneuron and preneuron spikes as the input parameter of a gate bias voltage pulse, synaptic spike-timing-dependent plasticity learning behaviour is realized. The extreme sensitivity of electrical properties to defects in correlated oxides may make them a particularly suitable class of materials to realize artificial biological circuits that can be operated at and above room temperature and seamlessly integrated into conventional electronic circuits. PMID:24177330
The Neurogenetic Correlates of Consciousness
NASA Astrophysics Data System (ADS)
Grandy, John K.
2013-09-01
The neurogenetic correlates of consciousness (NgCC) is a new field of consciousness studies that focuses on genes that have an effect on or are involved in the continuum of neuron-based consciousness. A framework of consciousness based on the neural correlates of consciousness (NCC) has already been established by Francis Crick and Christof Kock. In this work I propose that there are NgCC underlying the NCC which are both active during the conscious experience. So how are genes involved? There are two significant connections between DNA and neurons that are involved in the conscious experience. First, any brain system can be adversely affected by underlying genetic abnormalities which can be expressed in an individual at birth, in adulthood, or later in life. Second, the DNA molecule does not lay dormant while the neuron runs on autopilot. DNA is active in translating and transcribing RNA and protein products that are utilized during neuron functioning. Without these products being continuously produced by the DNA during a conscious experience the neurons would cease to function correctly and be rendered unable to provide a continuum of human consciousness. Consequently, in addition to NCC, NgCC must be factored in when appreciating a conscious event. In this work I will discuss and explain some NgCC citing several examples.
Oral health correlates of captivity.
Kapoor, Varsha; Antonelli, Tyler; Parkinson, Jennifer A; Hartstone-Rose, Adam
2016-08-01
The predominant diet fed to captive carnivores in North America consists of ground meat formulated to provide full nutritional requirements. However, this ground meat diet completely lacks the mechanical properties (i.e., toughness and hardness) of the foods these animals would consume in the wild. The goal of this study is to evaluate the effect of captivity on oral health by comparing the prevalence of periodontal disease and dental calculus accumulation in wild and captive lions and tigers (Panthera leo and Panthera tigris), and to also correlate oral health with cranial morphology in these specimens. To achieve this, 34 adult lion and 29 adult tiger skulls were scored for the presence and extent of dental calculus and periodontal disease. These oral health scores were also compared to cranial deformations examined in a previous study. We found that the occurrence and severity of calculus buildup and periodontal disease was significantly higher in captive felids compared to their wild counterparts. Further, higher calculus accumulation occurred on the posterior teeth when compared to the anterior teeth, while an opposite trend for periodontal disease was observed. We also found a significant correlation between oral health and cranial morphology of lions and tigers. The results suggest that food mechanical properties are significant factors contributing to oral health in felids. PMID:27473998
Oral health correlates of captivity.
Kapoor, Varsha; Antonelli, Tyler; Parkinson, Jennifer A; Hartstone-Rose, Adam
2016-08-01
The predominant diet fed to captive carnivores in North America consists of ground meat formulated to provide full nutritional requirements. However, this ground meat diet completely lacks the mechanical properties (i.e., toughness and hardness) of the foods these animals would consume in the wild. The goal of this study is to evaluate the effect of captivity on oral health by comparing the prevalence of periodontal disease and dental calculus accumulation in wild and captive lions and tigers (Panthera leo and Panthera tigris), and to also correlate oral health with cranial morphology in these specimens. To achieve this, 34 adult lion and 29 adult tiger skulls were scored for the presence and extent of dental calculus and periodontal disease. These oral health scores were also compared to cranial deformations examined in a previous study. We found that the occurrence and severity of calculus buildup and periodontal disease was significantly higher in captive felids compared to their wild counterparts. Further, higher calculus accumulation occurred on the posterior teeth when compared to the anterior teeth, while an opposite trend for periodontal disease was observed. We also found a significant correlation between oral health and cranial morphology of lions and tigers. The results suggest that food mechanical properties are significant factors contributing to oral health in felids.
Fiducial marker for correlating images
Miller, Lisa Marie; Smith, Randy J.; Warren, John B.; Elliott, Donald
2011-06-21
The invention relates to a fiducial marker having a marking grid that is used to correlate and view images produced by different imaging modalities or different imaging and viewing modalities. More specifically, the invention relates to the fiducial marking grid that has a grid pattern for producing either a viewing image and/or a first analytical image that can be overlaid with at least one other second analytical image in order to view a light path or to image different imaging modalities. Depending on the analysis, the grid pattern has a single layer of a certain thickness or at least two layers of certain thicknesses. In either case, the grid pattern is imageable by each imaging or viewing modality used in the analysis. Further, when viewing a light path, the light path of the analytical modality cannot be visualized by viewing modality (e.g., a light microscope objective). By correlating these images, the ability to analyze a thin sample that is, for example, biological in nature but yet contains trace metal ions is enhanced. Specifically, it is desired to analyze both the organic matter of the biological sample and the trace metal ions contained within the biological sample without adding or using extrinsic labels or stains.
Correlation of phantom-based and log file patient-specific QA with complexity scores for VMAT.
Agnew, Christina E; Irvine, Denise M; McGarry, Conor K
2014-11-08
The motivation for this study was to reduce physics workload relating to patient- specific quality assurance (QA). VMAT plan delivery accuracy was determined from analysis of pre- and on-treatment trajectory log files and phantom-based ionization chamber array measurements. The correlation in this combination of measurements for patient-specific QA was investigated. The relationship between delivery errors and plan complexity was investigated as a potential method to further reduce patient-specific QA workload. Thirty VMAT plans from three treatment sites - prostate only, prostate and pelvic node (PPN), and head and neck (H&N) - were retrospectively analyzed in this work. The 2D fluence delivery reconstructed from pretreatment and on-treatment trajectory log files was compared with the planned fluence using gamma analysis. Pretreatment dose delivery verification was also car- ried out using gamma analysis of ionization chamber array measurements compared with calculated doses. Pearson correlations were used to explore any relationship between trajectory log file (pretreatment and on-treatment) and ionization chamber array gamma results (pretreatment). Plan complexity was assessed using the MU/ arc and the modulation complexity score (MCS), with Pearson correlations used to examine any relationships between complexity metrics and plan delivery accu- racy. Trajectory log files were also used to further explore the accuracy of MLC and gantry positions. Pretreatment 1%/1 mm gamma passing rates for trajectory log file analysis were 99.1% (98.7%-99.2%), 99.3% (99.1%-99.5%), and 98.4% (97.3%-98.8%) (median (IQR)) for prostate, PPN, and H&N, respectively, and were significantly correlated to on-treatment trajectory log file gamma results (R = 0.989, p < 0.001). Pretreatment ionization chamber array (2%/2 mm) gamma results were also significantly correlated with on-treatment trajectory log file gamma results (R = 0.623, p < 0.001). Furthermore, all gamma results displayed a
Isbell, M; Ricker, J; Gordian, M E; Duffy, L K
1999-10-29
The benzene and toluene levels inside of eight homes with attached garages were measured during July 1998 in Fairbanks, Alaska. A thermal desorption tube method and charcoal tube method were used to collect and analyze samples (thermal desorption tube method %RDS = 1.9 for n = 6; charcoal tube method %RDS = 6.5 for n = 4). Results for both methods were compared and showed indoor benzene levels ranging between 1.2 and 72 ppbv. The charcoal tube method usually gave lower results than the thermal desorption method. Nevertheless, the difference observed in benzene levels from each method was not significant as determined by application of the Wilcoxon t-test to these data. Using the thermal desorption method, the range of toluene found in homes was 0.1-111 ppbv. A correlation between toluene and benzene levels suggested the same point source. The benzene and toluene content of the indoor air and the number of small engines stored in the attached garage was also correlated. There was no correlation found between the urinary biomarker concentrations and the level of benzene or toluene measured inside the homes in the summer.
Pack hike test finishing time for Australian firefighters: pass rates and correlates of performance.
Phillips, M; Petersen, A; Abbiss, C R; Netto, K; Payne, W; Nichols, D; Aisbett, B
2011-03-01
The pack hike test (PHT, 4.83 km hike wearing a 20.4-kg load) was devised to determine the job readiness of USA wildland firefighters. This study measured PHT performance in a sample of Australian firefighters who currently perform the PHT (career land management firefighters, LMFF) and those who do not (suburban/regional volunteer firefighters, VFF). The study also investigated the relationships between firefighters' PHT performance and their performance across a range of fitness tests for both groups. Twenty LMFF and eighteen age-, body mass-, and height-matched VFF attempted the PHT, and a series of muscular endurance, power, strength and cardiorespiratory fitness tests. Bivariate correlations between the participants' PHT finishing time and their performance in a suite of different fitness tests were determined using Pearson's product moment correlation coefficient. The mean PHT finishing time for LMFF (42.2 ± 2.8 min) was 9 ± 14% faster (p = 0.001) than for VFF (46.1 ± 3.6 min). The pass rate (the percentage of participants who completed the PHT in under 45 min) for LMFF (90%) was greater than that of VFF (39%, p = 0.001). For LMFF, VO(2peak) in L min(-1)(r = -0.66, p = 0.001) and the duration they could sustain a grip 'force' of 25 kg (r = -0.69, p = 0.001) were strongly correlated with PHT finishing time. For VFF, VO(2peak) in mL kg(-1) min(-1)(r = -0.75, p = 0.002) and the duration they could hold a 1.2-m bar attached to 45.5 kg in a 'hose spray position' (r = -0.69, p = 0.004) were strongly correlated with PHT finishing time. This study shows that PHT fitness-screening could severely limit the number of VFF eligible for duty, compromising workforce numbers and highlights the need for specific and valid firefighter fitness standards. The results also demonstrate the strong relationships between PHT performance and firefighters' cardiorespiratory fitness and local muscular endurance. Those preparing for the PHT should focus their training on these fitness
Measurement and Correlation of Ambient VOCs in Windsor, Ontario, Canada and Detroit, Michigan, USA
NASA Astrophysics Data System (ADS)
Miller, L. J.; You, H.; Xu, X.; Molaroni, S.; Lemke, L.; Weglicki, L.; Krouse, H.; Krajenta, R.
2009-05-01
An air quality study has been carried out in Windsor, Ontario, Canada and Detroit, Michigan, USA as part of a pilot research study undertaken by the Geospatial Determinants of Health Outcomes Consortium (GeoDHOC), a multidisciplinary, international effort aimed at understanding the health effects of air pollution in urban environments. Exposure to volatile organic compounds has long been associated with adverse health conditions such as atrophy of skeletal muscles, loss of coordination, neurological damage, dizziness, throat, nose, and eye irritation, nervous system depression, liver damage, and respiratory symptoms. Twenty-six species of ambient volatile organic compounds (VOCs) were monitored during a 2-week period in September, 2008 at 100 sites across Windsor and Detroit, using 3M # 3500 Organic Vapour Monitors. Ten species with highest concentrations were selected for further investigation; Toluene (mean concentration =4.14 μm/m3), (m+p)-Xylene (2.30 μm/m3), Hexane (1.87 μm/m3), Benzene (1.37 μm/m3), 1,2,4-Trimethylbenzene (0.87 μm/m3), Dichloromethane (0.77 μm/m3), Ethylbenzene (0.68 μm/m3), o-Xylene (0.63 μm/m3), n-Decane (0.42 μm/m3), and 1,3,5-Trimethylbenzene (0.39 μm/m3). Comparison to a similar investigation in Sarnia, Ontario in October 2005 revealed that the mean concentrations of VOCs were higher in Windsor-Detroit for all species by a significant margin (31-958%), indicating substantial impact of local industrial and vehicular emissions in the WindsorVDetroit area. For most VOCs, the concentrations were higher in Detroit than in Windsor. The mean concentration of total VOC was 9.7 μm/m3 in Windsor, which is slightly higher than that in Sarnia in 2005 (7.9 um/m3), whilst total VOC concentration in Detroit was much higher (16.5 μm/m3). There were strong correlations among several of the 10 species, with the highest Pearson correlation coefficients (r=0.78 - 0.99, p<0.05) amongst the BTEX (benzene, toluene, ethylbenzene, and xylenes) group
Tunneling in strongly correlated materials
NASA Astrophysics Data System (ADS)
Maltseva, Marianna
Tunneling studies of strongly correlated materials provide information about the nature of electronic correlations, which is vital for investigation of emergent materials at the microscopic level. In particular, scanning tunneling spectroscopy/microscopy (STS/STM) studies have made major contributions to understanding cuprate superconductors (66), yet there is a sense that huge STM data arrays contain much more precious information to be extracted and analyzed. One of the most pressing questions in the field is how to improve the data analysis, so as to extract more information from STM data. A dominant trend in STM data analysis has been to interpret the data within a particular microscopic model, while using only basic data analysis tools. To decrease the reliance of the STM data interpretation on particular microscopic models, further advances in data analysis methods are necessary. In Chapter 2 of this Thesis, we discuss how one can extract information about the phase of the order parameter from STM data. We show that symmetrized and anti-symmetrized correlators of local density of states give rise to observable coherence factor effects. In Chapter 3, we apply this framework to analyze the recent scanning tunneling experiments on an underdoped cuprate superconductor Ca2-xNaxCuO2Cl2 by T. Hanaguri et al. (60). In Chapter 4, we propose a model for nodal quasiparticle scattering in a disordered vortex lattice. Recently, scanning tunneling studies of a Kondo lattice material URu2Si2 became possible (117). If it proves possible to apply scanning tunneling spectroscopy to Kondo lattice materials, then remarkable new opportunities in the ongoing investigation may emerge. In Chapter 5, we examine the effect of co-tunneling to develop a theory of tunneling into a Kondo lattice. We find that the interference between the direct tunneling and the co-tunneling channels leads to a novel asymmetric lineshape, which has two peaks and a gap. The presence of the peaks suggests
Vertical velocity-CCN correlations
NASA Astrophysics Data System (ADS)
Hudson, J. G.; Noble, S. R.
2013-12-01
The realization that smaller cloud droplets evaporate more readily (Xue and Feingold 2006; Jiang et al. 2002) gives rise to an anti-indirect aerosol effect (IAE); less cloudiness with pollution. The greater latent heat exchange of the greater evaporation in more polluted clouds adds TKE and buoyancy gradients that can enhance vertical velocity (W), mixing and entrainment (Zhao and Austin 2005). Stronger W can increase horizontal motions, which can further enhance droplet evaporation, which further enhances latent heat exchange and vertical motions, thus, positive feedback. This could also include latent heat released during condensation (Lee and Feingold 2010), which is more rapid for the greater surface areas of the smaller more numerous droplets. These theories imply a positive relationship between within-cloud W variations; i.e., standard deviation of W (σw) and CCN concentration (NCCN) rather than W and NCCN. This implies greater turbulence in polluted clouds, which could possibly counteract the reduction of cloudiness of anti-IAE. During two stratus cloud projects, 50 cloud penetrations in 9 MASE flights and 34 cloud penetrations in 13 POST flights, within-cloud σw-NCCN showed correlation coefficients (R) of 0.50 and 0.39. Panel a shows similar within-cloud σw-NCCN R in all altitude bands for 17 RICO flights in small cumulus clouds. R for W-NCCN showed similar values but only at low altitudes. Out-of-cloud σw-NCCN showed similar high values except at the highest altitudes. Within-cloud σw showed higher R than within-cloud W with droplet concentrations (Nc), especially at higher altitudes. Panel b for 13 ICE-T cumulus cloud flights in the same location as RICO but during the opposite season, however, showed σw and W uncorrelated with NCCN at all altitudes; and W and σw correlated with Nc only at the highest altitudes. On the other hand, out-of-cloud σw was correlated with NCCN at all altitudes with R similar to the corresponding R of the other projects
CORRELATIONS IN CONFINED QUANTUM PLASMAS
DUFTY J W
2012-01-11
This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed
Correlation effects in metallic cohesion
NASA Astrophysics Data System (ADS)
Haydock, Roger
2014-03-01
The electronic contribution to the cohesive energy of a correlated metal is the sum of the transition energies for adding successive electrons at successive Fermi levels until the system reaches its final electron density. This can be computed as the integral of energy over the projected density of transitions for adding single electrons to localized orbitals. In the case of independent electrons, this reduces to the usual integral over the projected density of states. As an example, cohesive energies for some simple transition metal structures are calculated using the recursion method* with a Hubbard repulsion between electrons. * Phys. Rev. B 61, 7953-64 Work supported by the Richmond F. Snyder gift to the University of Oregon.
Correlative microscopy of detergent granules.
van Dalen, G; Nootenboom, P; Heussen, P C M
2011-03-01
The microstructure of detergent products for textile cleaning determines to a large extent the physical properties of these products. Correlative microscopy was used to reveal the microstructure by reconciling images obtained by scanning electron microscopy with energy dispersive X-ray analysis, X-ray microtomography and Fourier transform infrared microscopy. These techniques were applied on the same location of a subsample of a spray-dried detergent base powder embedded in polyacrylate. In this way, the three-dimensional internal and external structure of detergent granules could be investigated from milli to nano scale with detailed spatial information about the components present. This will generate knowledge how to design optimal microstructures for laundry products to obtain product properties demanded by the market. This method is also very useful for other powder systems used in a large variety of industries (e.g. for pharmaceutical, food, ceramic and metal industries).
Physiological correlates of mental workload
NASA Technical Reports Server (NTRS)
Zacharias, G. L.
1980-01-01
A literature review was conducted to assess the basis of and techniques for physiological assessment of mental workload. The study findings reviewed had shortcomings involving one or more of the following basic problems: (1) physiologic arousal can be easily driven by nonworkload factors, confounding any proposed metric; (2) the profound absence of underlying physiologic models has promulgated a multiplicity of seemingly arbitrary signal processing techniques; (3) the unspecified multidimensional nature of physiological "state" has given rise to a broad spectrum of competing noncommensurate metrics; and (4) the lack of an adequate definition of workload compels physiologic correlations to suffer either from the vagueness of implicit workload measures or from the variance of explicit subjective assessments. Using specific studies as examples, two basic signal processing/data reduction techniques in current use, time and ensemble averaging are discussed.
Correlating thalamocortical connectivity and activity
NASA Astrophysics Data System (ADS)
da Fontoura Costa, Luciano; Sporns, Olaf
2006-07-01
The segregated regions of the mammalian cerebral cortex and thalamus form an extensive and complex network, whose structure and function are still only incompletely understood. The present letter describes an application of the concepts of complex networks and random walks that allows the identification of nonrandom, highly structured features of thalamocortical connections and their potential effects on dynamic interactions between cortical areas in the cat brain. Utilizing large-scale anatomical data sets of this thalamocortical system, we investigate uniform random walks in such a network by considering the steady state eigenvector of the respective stochastic matrix. It is shown that thalamocortical connections are organized in such a way as to guarantee strong correlation between the outdegree and occupancy rate (a stochastic measure potentially related to activation) of each cortical area. Possible organizational principles underlying this effect are identified and discussed.
Fully resolved NMR correlation spectroscopy.
Pitoux, Daisy; Plainchont, Bertrand; Merlet, Denis; Hu, Zhaoyu; Bonnaffé, David; Farjon, Jonathan; Giraud, Nicolas
2015-06-15
A new correlation experiment cited as "push-G-SERF" is reported. In the resulting phased 2D spectrum, the chemical shift information is selected along the direct dimension, whereas scalar couplings involving a selected proton nucleus are edited in the indirect domain. The robustness of this pulse sequence is demonstrated on compounds with increasing structural and spectral complexity, using state-of-the-art spectrometers. It allows for full resolution of both dimensions of the spectrum, yielding a straightforward assignment and measurement of the coupling network around a given proton in the molecule. This experiment is intended for chemists who want to address efficiently the structural analysis of molecules with an overcrowded spectrum.
Vibration analysis using digital correlation
NASA Technical Reports Server (NTRS)
Gilbert, John A.; Lehner, David L.; Dudderar, T. Dixon; Matthys, Donald R.
1988-01-01
This paper demonstrates the use of a computer-based optical method for locating the positions of nodes and antinodes in vibrating members. Structured light patterns are projected at an angle onto the vibrating surface using a 35 mm slide projector. The vibrating surface and the projected images are captured in a time averaged photograph which is subsequently digitized. The inherent fringe patterns are filtered to determine amplitudes of vibration, and computer programs are used to compare the time averaged images to images recorded prior to excitation to locate nodes and antinodes. Some of the influences of pattern regularity on digital correlation are demonstrated, and a speckle-based method for determining the mode shapes and the amplitudes of vibration with variable sensitivity is suggested.
Investigation of correlation classification techniques
NASA Technical Reports Server (NTRS)
Haskell, R. E.
1975-01-01
A two-step classification algorithm for processing multispectral scanner data was developed and tested. The first step is a single pass clustering algorithm that assigns each pixel, based on its spectral signature, to a particular cluster. The output of that step is a cluster tape in which a single integer is associated with each pixel. The cluster tape is used as the input to the second step, where ground truth information is used to classify each cluster using an iterative method of potentials. Once the clusters have been assigned to classes the cluster tape is read pixel-by-pixel and an output tape is produced in which each pixel is assigned to its proper class. In addition to the digital classification programs, a method of using correlation clustering to process multispectral scanner data in real time by means of an interactive color video display is also described.
Correlation method of electrocardiogram analysis
NASA Astrophysics Data System (ADS)
Strinadko, Marina M.; Timochko, Katerina B.
2002-02-01
The electrocardiograph method is the informational source for functional heart state characteristics. The electrocardiogram parameters are the integrated map of many component characteristics of the heart system and depend on disturbance requirements of each device. In the research work the attempt of making the skeleton diagram of perturbation of the heart system is made by the characteristic description of its basic components and connections between them through transition functions, which are written down by the differential equations of the first and second order with the purpose to build-up and analyze electrocardiogram. Noting the vector character of perturbation and the various position of heart in each organism, we offer own coordinate system connected with heart. The comparative analysis of electrocardiogram was conducted with the usage of correlation method.
Optimal measurements for nonlocal correlations
NASA Astrophysics Data System (ADS)
Schwarz, Sacha; Stefanov, André; Wolf, Stefan; Montina, Alberto
2016-08-01
A problem in quantum information theory is to find the experimental setup that maximizes the nonlocality of correlations with respect to some suitable measure such as the violation of Bell inequalities. There are however some complications with Bell inequalities. First and foremost it is unfeasible to determine the whole set of Bell inequalities already for a few measurements and thus unfeasible to find the experimental setup maximizing their violation. Second, the Bell violation suffers from an ambiguity stemming from the choice of the normalization of the Bell coefficients. An alternative measure of nonlocality with a direct information-theoretic interpretation is the minimal amount of classical communication required for simulating nonlocal correlations. In the case of many instances simulated in parallel, the minimal communication cost per instance is called nonlocal capacity, and its computation can be reduced to a convex-optimization problem. This quantity can be computed for a higher number of measurements and turns out to be useful for finding the optimal experimental setup. Focusing on the bipartite case, we present a simple method for maximizing the nonlocal capacity over a given configuration space and, in particular, over a set of possible measurements, yielding the corresponding optimal setup. Furthermore, we show that there is a functional relationship between Bell violation and nonlocal capacity. The method is illustrated with numerical tests and compared with the maximization of the violation of CGLMP-type Bell inequalities on the basis of entangled two-qubit as well as two-qutrit states. Remarkably, the anomaly of nonlocality displayed by qutrits turns out to be even stronger if the nonlocal capacity is employed as a measure of nonlocality.
Correlated randomness and switching phenomena
NASA Astrophysics Data System (ADS)
Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.
2010-08-01
One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.
Astrochemical Correlations in Molecular Clouds
NASA Astrophysics Data System (ADS)
Gaches, Brandt A.L.; Offner, Stella
2014-06-01
We investigate the spectral correlations between different chemical tracers used to observe molecular clouds. We study a 600 Solar Mass molecular cloud with Mach number 6.6 modeled using the magnetohydrodynamic code ORION. The chemical abundances are calculated by 3D-PDR, a three-dimensional astrochemical code using a full network of 3300 reactions and 215 species. We take synthetic observations of 16 different species using the non-LTE radiative transfer code RADMC-3D. The effects of different lines of sight and spatial resolution on the emission maps of the 16 different species will be discussed in this talk.We use the Spectral Correlation Function to quantify the structure of the simulated cloud in position-position-velocity space, which measures the average rms velocity between spectra separated by a given length scale. This statistic has been shown to be sensitive to global hydrodynamic parameters, such as the sonic Mach number and velocity dispersion. The SCF is analytically fit by a power law, with the slope being the one free parameter. We verify that the SCF is generally insensitive to the sightline through the cloud. We discover that the beam size has a distinct effect on different chemical tracers. However, the change is not large enough to move the SCF slopes into different parts of the parameter space. This is the first quantitative 3D study of the spectral similarity of a variety of species. We predict the observed SCF for a broad range of observational tracers, and thus, identify complementary species. In particular, we show that the pairs C and CO, C+ and CN, NH3 and H2CS have very similar SCFs. The results from this study will also give observers a guide for selecting which chemical tracers would be best for observing different length scales.
Electron correlations in copper oxides
NASA Astrophysics Data System (ADS)
Jefferson, J. H.
A model which explicitly takes into account the hybridization of copper and oxygen orbitals and Coulomb correlations in copper-oxide chains and layers is considered. Degenerate perturbation theory is used to derive various effective Hamiltonians and shown to give rise to effective interactions which would be absent from a model that did not account for the oxygen states explicitly. In particular, there are hole-hole repulsion terms which mitigate against pairing. Exact solutions of the single hole problem and numerical solutions of the two-hole case for CuO chains confirm that the holes repel in the large correlation limit. Nous considérons un modèle dans lequel l'hybridation des orbitales de cuivre et d'oxygène et les corrélations de Coulomb en chaînes et en couches sont données explicitement. Les Hamiltoniens effectifs sont dérivés en utilisant la théorie de la perturbation dégénérée. On trouve les interactions effectives qui sont absentes d'un modèle dans lequel les états de l'oxygène ne sont pas considérés explicitement. Notamment, les forces répulsives entre les trous produisent une diminution de la probabilité d'association. Les solutions précises du problème pour un trou simple, et les solutions numériques du cas de deux trous dans les chaînes de CuO, confirment que dans la limite pour les corrélations fortes, les trous subissent une force répulsive.
NASA Astrophysics Data System (ADS)
Ratnasari, D.; Nazir, F.; Toresano, L. O. H. Z.; Pawiro, S. A.; Soejoko, D. S.
2016-03-01
The prevalence of chronic renal diseases in Indonesia has an increasing annual trend, because it is frequently unrecognized and often co-exists with other disease. GFR and ERPF are parameters currently utilized to estimate renal function at routine renal scintigraphy 99m-Tc DTPA study. This study used 99m-Tc DTPA to measure GFR and ERPF. The purpose of this study was to find the correlation between ERPF and GFR, for ERPF analysis with Schlegel's method, and GFR analysis with Gate's method, as well as to find correction factor between both variables. Analysis of renal scintigraphy has been performed at Department of Nuclear Medicine Pertamina Center Hospital to thirty patient images acquired from 2014 to 2015 which were analyzed retrospectively data, using gamma camera dual head with counting method from renal scintigraphy 99m-Tc DTPA study. The calculation was executed by means of both display and manual calculation. Pearson's statistical analysis resulted on Positive Correlation for all data, with ERPF and GFR (display) showing Strongly Positive Correlation (r = 0.82; p- value < 0.05). Standard deviation was found to be 27.58 and 107.64 for GFR and ERPF (display), respectively. Our result indicated that the use of 99mTc-DTPA measure ERPF was not recommended.
A Two Factor ANOVA-like Test for Correlated Correlations: CORANOVA
ERIC Educational Resources Information Center
Bilker, Warren B.; Brensinger, Colleen; Gur, Ruben C.
2004-01-01
Testing homogeneity of correlations with Fisher's Z is inappropriate when correlations are themselves correlated. Suppose measurements of brain activation and performance are taken before and during a verbal memory task. Of interest are changes in activity gradients in specific regions, R1, R2, R3, and performance, V. The "correlated correlations"…
The Effect of Error Correlation on Interfactor Correlation in Psychometric Measurement
ERIC Educational Resources Information Center
Westfall, Peter H.; Henning, Kevin S. S.; Howell, Roy D.
2012-01-01
This article shows how interfactor correlation is affected by error correlations. Theoretical and practical justifications for error correlations are given, and a new equivalence class of models is presented to explain the relationship between interfactor correlation and error correlations. The class allows simple, parsimonious modeling of error…
Inferring correlations: from exemplars to categories.
Vogel, Tobias; Kutzner, Florian; Freytag, Peter; Fiedler, Klaus
2014-10-01
Research and theorizing suggest a processing advantage of category-level correlations over exemplar-level correlations. That research has also shown that category-level correlations serve as a proxy for inferring exemplar-level correlations. For example, an individual may learn that the demand for a product category, like cheese, in one store predicts the demand for this category in another. The individual could then draw the unwarranted conclusion that the demand for an exemplar, like cheddar, would also predict the demand for this exemplar in the other store. This notion is supported by previous experiments demonstrating that the subjective exemplar-level correlation follows the implication of the category-level correlation. However, in virtually all previous experiments suggesting a processing advantage for category-level over exemplar-level correlations, the stimulus correlation at the category level was substantial, whereas the correlation at the exemplar level was weak. Here, we tested the hypothesis that individuals process the level that is most informative, either the exemplar or the category level. We presented participants with a zero correlation at the category level, but varied the correlation at the exemplar level. Participants presented with a zero correlation across exemplar products correctly reproduced a zero correlation across product categories. When presented with a substantial correlation at the exemplar level, however, they erroneously reproduced a similar correlation at the category level. These findings therefore imply that there is no general processing advantage for correlations at higher aggregation levels. Instead, individuals seemingly attend to the level that holds the most regular information. Findings are discussed regarding the role of covariation strength in correlation detection and use. PMID:24493021
Welker, Kelli L; Orkin, Joseph D; Ryan, Timothy M
2009-10-01
The semicircular canal system tracks head rotation and provides sensory input for the reflexive stabilization of gaze and posture. The purpose of this study was to investigate the intraspecific and intraindividual variation in the size of the three semicircular canals. The right and left temporal bones were extracted from 31 individuals of the short-tailed shrew (Blarina brevicauda) and scanned on a high-resolution x-ray computed tomography system. The radius of curvature was calculated for each of the three semicircular canals for each side. Paired t-tests and independent sample t-tests indicated no significant differences in canal size between the right and left canals of the same individuals or between those of males and females of the same species. Pearson product moment correlation analyses demonstrated that there was no significant correlation between canal size and body mass in this sample. PMID:19619167
Motunrayo Ibrahim, Fausat
2013-01-01
Background: Gardening is a worthwhile adventure which engenders health optimization. Yet, a dearth of evidences that highlights motivations to engage in gardening exists. This study examined willingness to engage in gardening and its correlates, including some socio-psychological, health related and socio-demographic variables. Methods: In this cross-sectional survey, 508 copies of a structured questionnaire were randomly self administered among a group of civil servants of Oyo State, Nigeria. Multi-item measures were used to assess variables. Step wise multiple regression analysis was used to identify predictors of willingness to engage in gardening Results: Simple percentile analysis shows that 71.1% of respondents do not own a garden. Results of step wise multiple regression analysis indicate that descriptive norm of gardening is a good predictor, social support for gardening is better while gardening self efficacy is the best predictor of willingness to engage in gardening (P< 0.001). Health consciousness, gardening response efficacy, education and age are not predictors of this willingness (P> 0.05). Results of t-test and ANOVA respectively shows that gender is not associated with this willingness (P> 0.05), but marital status is (P< 0.05). Conclusion: Socio-psychological characteristics and being married are very relevant in motivations to engage in gardening. The nexus between gardening and health optimization appears to be highly obscured in this population. PMID:24688974
Correlation of pregnancy outcome with quadruple screening test at second trimester
Yazdani, Shahla; Rouholahnejad, Rahele; Asnafi, Nesa; Sharbatdaran, Majid; Zakershob, Marziihe; Bouzari, Zinatossadat
2015-01-01
Background: Abnormal levels of the markers AFP, hCG, and uE3 could be useful in predicting adverse pregnancy outcomes. This study was designed to determine the correlation between second trimester maternal serum markers and adverse pregnancy outcome (APO). Methods: In this historical cohort study, we randomly followed 231 obstetric patients with quadruple screening test in 14-18 weeks of gestation from March 2012 to March 2013 in a medical laboratory in Babol, Iran. We measured maternal serum levels of alphafetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and inhibin-A. The risk of adverse pregnancy outcomes (APOs) were then compared between patients with negative and positive test results. We used Chi-square and Fisher-exact tests for qualitative variables and t-test for quantitative variables. Demographic differences between the two groups were minimized by applying logistic regression. Results: The risk of having an APO such as pre-eclampsia (p=0.008), fetal growth restriction (p=0.028) and premature rupture of membrane (p=0.040) increased significantly in patients with abnormal markers. Conclusion: Abnormal results of quadruple screening test could be associated with APO in women with normal appearing fetus. PMID:26913244