Modified Biserial Correlation Coefficients.
Kraemer, Helena Chmura
1981-01-01
Asymptotic distribution theory of Brogden's form of biserial correlation coefficient is derived and large sample estimates of its standard error obtained. Its relative efficiency to the biserial correlation coefficient is examined. Recommendations for choice of estimator of biserial correlation are presented. (Author/JKS)
Shi, Ming-Guang; Xia, Jun-Feng; Li, Xue-Ling; Huang, De-Shuang
2010-03-01
Identifying protein-protein interactions (PPIs) is critical for understanding the cellular function of the proteins and the machinery of a proteome. Data of PPIs derived from high-throughput technologies are often incomplete and noisy. Therefore, it is important to develop computational methods and high-quality interaction dataset for predicting PPIs. A sequence-based method is proposed by combining correlation coefficient (CC) transformation and support vector machine (SVM). CC transformation not only adequately considers the neighboring effect of protein sequence but describes the level of CC between two protein sequences. A gold standard positives (interacting) dataset MIPS Core and a gold standard negatives (non-interacting) dataset GO-NEG of yeast Saccharomyces cerevisiae were mined to objectively evaluate the above method and attenuate the bias. The SVM model combined with CC transformation yielded the best performance with a high accuracy of 87.94% using gold standard positives and gold standard negatives datasets. The source code of MATLAB and the datasets are available on request under smgsmg@mail.ustc.edu.cn.
Wavelet Correlation Coefficient of 'strongly correlated' financial time series
Ashok Razdan
2003-01-01
In this paper we use wavelet concepts to show that correlation coefficient between two financial data's is not constant but varies with scale from high correlation value to strongly anti-correlation value This studies is important because correlation coefficient is used to quantify degree of independence between two variables. In econophysics correlation coefficient forms important input to evolve hierarchial tree and minimum spanning tree of financial data.
Spatial correlation coefficient images for ultrasonic detection.
Cepel, Raina; Ho, K C; Rinker, Brett A; Palmer, Donald D; Lerch, Terrence P; Neal, Steven P
2007-09-01
In ultrasonics, image formation and detection are generally based on signal amplitude. In this paper, we introduce correlation coefficient images as a signal-amplitude independent approach for image formation. The correlation coefficients are calculated between A-scans digitized at adjacent measurement positions. In these images, defects are revealed as regions of high or low correlation relative to the background correlations associated with noise. Correlation coefficient and C-scan images are shown to demonstrate flat-bottom-hole detection in a stainless steel annular ring and crack detection in an aluminum aircraft structure.
Matrix correlations for high-dimensional data: The modified RV-coefficient
Smilde, A.K.; Kiers, H.A.L.; Bijlsma, S.; Rubingh, C.M.; Erk, M.J. van
2009-01-01
Motivation: Modern functional genomics generates high-dimensional datasets. It is often convenient to have a single simple number characterizing the relationship between pairs of such high-dimensional datasets in a comprehensive way. Matrix correlations are such numbers and are appealing since they
Matrix correlations for high-dimensional data : The modified RV-coefficient
Smilde, A. K.; Kiers, H. A. L.; Bijlsma, S.; Rubingh, C. M.; van Erk, M. J.
2009-01-01
Motivation: Modern functional genomics generates high-dimensional datasets. It is often convenient to have a single simple number characterizing the relationship between pairs of such high-dimensional datasets in a comprehensive way. Matrix correlations are such numbers and are appealing since they
Matrix correlations for high-dimensional data: the modified RV-coefficient
Smilde, A.K.; Kiers, H.A.L.; Bijlsma, S.; Rubingh, C.M.; van Erk, M.J.
2009-01-01
Motivation: Modern functional genomics generates high-dimensional datasets. It is often convenient to have a single simple number characterizing the relationship between pairs of such high-dimensional datasets in a comprehensive way. Matrix correlations are such numbers and are appealing since they
Correlation and prediction of gaseous diffusion coefficients.
Marrero, T. R.; Mason, E. A.
1973-01-01
A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high-pressure effects are not. The results are directly applicable to multicomponent mixtures.
Coefficient of Partial Correlation and Its Calculation
Institute of Scientific and Technical Information of China (English)
段全才; 张保法
1992-01-01
This thesis offers the general concept of coefficient of partial correlation.Starting with regres-sion analysis,the paper,by using samples,infers the general formula of expressing coefficient of partial correlation by way of simple correlation coefficient.
Correlation Degree and Correlation Coefficient of Multi- Output Functions
Institute of Scientific and Technical Information of China (English)
JU Gui-zhi; ZHAO Ya-qun
2005-01-01
We present definitions of the correlation degree and correlation coefficient of multi-output functions. Two relationships about the correlation degree of multi-output functions are proved. One is between the correlation degree and independency,the other is between the correlation degree and balance. Especially the paper discusses the correlation degree of affine multioutput functions. We demonstrate properties of the correlation coefficient of multi-output functions. One is the value range of the correlation coefficient, one is the relationship between the correlation coefficient and independency, and another is the sufficient and necessary condition that two multi-output functions are equivalent to each other.
Alternatives to Pearson's and Spearman's Correlation Coefficients
Smarandache, Florentin
2008-01-01
This article presents several alternatives to Pearson's correlation coefficient and many examples. In the samples where the rank in a discrete variable counts more than the variable values, the mixtures that we propose of Pearson's and Spearman's correlation coefficients give better results.
Estimation of the simple correlation coefficient.
Shieh, Gwowen
2010-11-01
This article investigates some unfamiliar properties of the Pearson product-moment correlation coefficient for the estimation of simple correlation coefficient. Although Pearson's r is biased, except for limited situations, and the minimum variance unbiased estimator has been proposed in the literature, researchers routinely employ the sample correlation coefficient in their practical applications, because of its simplicity and popularity. In order to support such practice, this study examines the mean squared errors of r and several prominent formulas. The results reveal specific situations in which the sample correlation coefficient performs better than the unbiased and nearly unbiased estimators, facilitating recommendation of r as an effect size index for the strength of linear association between two variables. In addition, related issues of estimating the squared simple correlation coefficient are also considered.
Adler, Jeremy; Parmryd, Ingela
2010-08-01
The Pearson correlation coefficient (PCC) and the Mander's overlap coefficient (MOC) are used to quantify the degree of colocalization between fluorophores. The MOC was introduced to overcome perceived problems with the PCC. The two coefficients are mathematically similar, differing in the use of either the absolute intensities (MOC) or of the deviation from the mean (PCC). A range of correlated datasets, which extend to the limits of the PCC, only evoked a limited response from the MOC. The PCC is unaffected by changes to the offset while the MOC increases when the offset is positive. Both coefficients are independent of gain. The MOC is a confusing hybrid measurement, that combines correlation with a heavily weighted form of co-occurrence, favors high intensity combinations, downplays combinations in which either or both intensities are low and ignores blank pixels. The PCC only measures correlation. A surprising finding was that the addition of a second uncorrelated population can substantially increase the measured correlation, demonstrating the importance of excluding background pixels. Overall, since the MOC is unresponsive to substantial changes in the data and is hard to interpret, it is neither an alternative to nor a useful substitute for the PCC. The MOC is not suitable for making measurements of colocalization either by correlation or co-occurrence.
Concordance correlation coefficient applied to discrete data.
Carrasco, Josep L; Jover, Lluis
2005-12-30
In any field in which decisions are subject to measurements, interchangeability between the methods used to obtain these measurements is essential. To consider methods as interchangeable, a certain degree of agreement is needed between the measurements they provide. The concordance correlation coefficient is an index that assesses the strength of agreement and it has been widely applied in situations in which measurements are made on a continuous scale. Recently the concordance correlation coefficient has been defined as a specific intraclass correlation coefficient estimated by the variance components of a Normal-Normal mixed linear model. Although this coefficient was defined for the continuous scale case, it may also be used with a discrete scale. In this case the data are often transformed and normalized, and the concordance correlation is applied. This study discusses the expression of the concordance correlation coefficient for discrete Poisson data by means of the Poisson-Normal generalized linear mixed model. The behaviour of the concordance correlation coefficient estimate is assessed by means of a simulation study, in which the estimates were compared using four models: three Normal-Normal mixed models with raw data, log-transformed data and square-root transformed data, and the Poisson-Normal generalized linear mixed model. An example is provided in which two different methods are used to measure CD34+ cells.
Temporal correlation coefficient for directed networks.
Büttner, Kathrin; Salau, Jennifer; Krieter, Joachim
2016-01-01
Previous studies dealing with network theory focused mainly on the static aggregation of edges over specific time window lengths. Thus, most of the dynamic information gets lost. To assess the quality of such a static aggregation the temporal correlation coefficient can be calculated. It measures the overall possibility for an edge to persist between two consecutive snapshots. Up to now, this measure is only defined for undirected networks. Therefore, we introduce the adaption of the temporal correlation coefficient to directed networks. This new methodology enables the distinction between ingoing and outgoing edges. Besides a small example network presenting the single calculation steps, we also calculated the proposed measurements for a real pig trade network to emphasize the importance of considering the edge direction. The farm types at the beginning of the pork supply chain showed clearly higher values for the outgoing temporal correlation coefficient compared to the farm types at the end of the pork supply chain. These farm types showed higher values for the ingoing temporal correlation coefficient. The temporal correlation coefficient is a valuable tool to understand the structural dynamics of these systems, as it assesses the consistency of the edge configuration. The adaption of this measure for directed networks may help to preserve meaningful additional information about the investigated network that might get lost if the edge directions are ignored.
Clustering stocks using partial correlation coefficients
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.
The Evolution of Pearson's Correlation Coefficient
Kader, Gary D.; Franklin, Christine A.
2008-01-01
This article describes an activity for developing the notion of association between two quantitative variables. By exploring a collection of scatter plots, the authors propose a nonstandard "intuitive" measure of association; and by examining properties of this measure, they develop the more standard measure, Pearson's Correlation Coefficient. The…
Quantum Correlation Coefficients for Angular Coherent States
Institute of Scientific and Technical Information of China (English)
CHEN Wei; HE Yan; GUO Hao
2009-01-01
Quantum covariance and correlation coefficients of angular or SU(2) coherent states are directly calculated for all irreducible unitary representations.These results explicitly verify that the angular coherent states minimize the Robertson-Schrodinger uncertainty relation for all spins, which means that they are the so-called intelligent states.The same results can be obtained by the Schwinger representation approach.
Computer programs for the concordance correlation coefficient.
Crawford, Sara B; Kosinski, Andrzej S; Lin, Hung-Mo; Williamson, John M; Barnhart, Huiman X
2007-10-01
The CCC macro is presented for computation of the concordance correlation coefficient (CCC), a common measure of reproducibility. The macro has been produced in both SAS and R, and a detailed presentation of the macro input and output for the SAS program is included. The macro provides estimation of three versions of the CCC, as presented by Lin [L.I.-K. Lin, A concordance correlation coefficient to evaluate reproducibility, Biometrics 45 (1989) 255-268], Barnhart et al. [H.X. Barnhart, J.L. Haber, J.L. Song, Overall concordance correlation coefficient for evaluating agreement among multiple observers, Biometrics 58 (2002) 1020-1027], and Williamson et al. [J.M. Williamson, S.B. Crawford, H.M. Lin, Resampling dependent concordance correlation coefficients, J. Biopharm. Stat. 17 (2007) 685-696]. It also provides bootstrap confidence intervals for the CCC, as well as for the difference in CCCs for both independent and dependent samples. The macro is designed for balanced data only. Detailed explanation of the involved computations and macro variable definitions are provided in the text. Two biomedical examples are included to illustrate that the macro can be easily implemented.
The Evolution of Pearson's Correlation Coefficient
Kader, Gary D.; Franklin, Christine A.
2008-01-01
This article describes an activity for developing the notion of association between two quantitative variables. By exploring a collection of scatter plots, the authors propose a nonstandard "intuitive" measure of association; and by examining properties of this measure, they develop the more standard measure, Pearson's Correlation Coefficient. The…
Flash ADC data processing with correlation coefficients
Energy Technology Data Exchange (ETDEWEB)
Blyth, D.; Gibson, M.; Mcfarland, D.; Comfort, J.R., E-mail: Joseph.Comfort@asu.edu
2014-02-21
The large growth of flash ADC techniques for processing signals, especially in applications of streaming data, raises issues such as data flow through an acquisition system, long-term storage, and greater complexity in data analysis. In addition, experiments that push the limits of sensitivity need to distinguish legitimate signals from noise. The use of correlation coefficients is examined to address these issues. They are found to be quite successful well into the noise region. The methods can also be extended to Field Programmable Gate Array modules for compressing the data flow and greatly enhancing the event rate capabilities.
Modeling Complex System Correlation Using Detrended Cross-Correlation Coefficient
Directory of Open Access Journals (Sweden)
Keqiang Dong
2014-01-01
Full Text Available The understanding of complex systems has become an area of active research for physicists because such systems exhibit interesting dynamical properties such as scale invariance, volatility correlation, heavy tails, and fractality. We here focus on traffic dynamic as an example of a complex system. By applying the detrended cross-correlation coefficient method to traffic time series, we find that the traffic fluctuation time series may exhibit cross-correlation characteristic. Further, we show that two traffic speed time series derived from adjacent sections exhibit much stronger cross-correlations than the two speed series derived from adjacent lanes. Similarly, we also demonstrate that the cross-correlation property between the traffic volume variables from two adjacent sections is stronger than the cross-correlation property between the volume variables of adjacent lanes.
The Attenuation of Correlation Coefficients: A Statistical Literacy Issue
Trafimow, David
2016-01-01
Much of the science reported in the media depends on correlation coefficients. But the size of correlation coefficients depends, in part, on the reliability with which the correlated variables are measured. Understanding this is a statistical literacy issue.
Testing the Correlated Random Coefficient Model*
Heckman, James J.; Schmierer, Daniel; Urzua, Sergio
2010-01-01
The recent literature on instrumental variables (IV) features models in which agents sort into treatment status on the basis of gains from treatment as well as on baseline-pretreatment levels. Components of the gains known to the agents and acted on by them may not be known by the observing economist. Such models are called correlated random coe cient models. Sorting on unobserved components of gains complicates the interpretation of what IV estimates. This paper examines testable implications of the hypothesis that agents do not sort into treatment based on gains. In it, we develop new tests to gauge the empirical relevance of the correlated random coe cient model to examine whether the additional complications associated with it are required. We examine the power of the proposed tests. We derive a new representation of the variance of the instrumental variable estimator for the correlated random coefficient model. We apply the methods in this paper to the prototypical empirical problem of estimating the return to schooling and nd evidence of sorting into schooling based on unobserved components of gains. PMID:21057649
Tests of Hypotheses Arising In the Correlated Random Coefficient Model.
Heckman, James J; Schmierer, Daniel
2010-11-01
This paper examines the correlated random coefficient model. It extends the analysis of Swamy (1971), who pioneered the uncorrelated random coefficient model in economics. We develop the properties of the correlated random coefficient model and derive a new representation of the variance of the instrumental variable estimator for that model. We develop tests of the validity of the correlated random coefficient model against the null hypothesis of the uncorrelated random coefficient model.
On the misinterpretation of the correlation coefficient in pharmaceutical sciences.
Sonnergaard, J M
2006-09-14
The correlation coefficient is often used and more often misused as a universal parameter expressing the quality in linear regression analysis. The popularity of this dimensionless quantity is evident as it is easy to communicate and considered to be unproblematic to comprehend. However, illustrative examples will demonstrate that the correlation coefficient is highly ineffective as a stand-alone quantity without reference to the number of observations, the pattern of the data and the slope of the regression line. Much more efficient quality methodologies are available where the correct technique depends on the purpose of the investigation. These relevant and precise methods in quality assurance of linear regression as alternative to the correlation coefficient are presented.
Visualization of biological texture using correlation coefficient images.
Sviridov, Alexander P; Ulissi, Zachary; Chernomordik, Victor; Hassan, Moinuddin; Gandjbakhche, Amir H
2006-01-01
Subsurface structural features of biological tissue are visualized using polarized light images. The technique of Pearson correlation coefficient analysis is used to reduce blurring of these features by unpolarized backscattered light and to visualize the regions of high statistical similarities within the noisy tissue images. It is shown that under certain conditions, such correlation coefficient maps are determined by the textural character of tissues and not by the chosen region of interest, providing information on tissue structure. As an example, the subsurface texture of a demineralized tooth sample is enhanced from a noisy polarized light image.
On Estimation and Hypothesis Testing Problems for Correlation Coefficients
Kraemer, Helena Chmura
1975-01-01
A selection of statistical problems commonly encountered in psychological or psychiatric research concerning correlation coefficients are re-evaluated in the light of recently developed simplifications in the forms of the distribution theory of the intraclass correlation coefficient, of the product-moment correlation coefficient, and the Spearman…
Detection Performance of the Circular Correlation Coefficient Receiver,
of the squared modulus of the circular serial correlation coefficient is found when no signal is present, allowing computation of the detection...threshold. For small data records, as is typical in radar applications, the performance of the correlation coefficient detector is compared to a standard... Correlation Coefficient , Autoregressive, CFAR, Autocorrelation Estimation, Radar Receiver, and Digital Signal Processing.
A generalized concordance correlation coefficient for continuous and categorical data.
King, T S; Chinchilli, V M
2001-07-30
This paper discusses a generalized version of the concordance correlation coefficient for agreement data. The concordance correlation coefficient evaluates the accuracy and precision between two measures, and is based on the expected value of the squared function of distance. We have generalized this coefficient by applying alternative functions of distance to produce more robust versions of the concordance correlation coefficient. In this paper we extend the application of this class of estimators to categorical data as well, and demonstrate similarities to the kappa and weighted kappa statistics. We also introduce a stratified concordance correlation coefficient which adjusts for explanatory factors, and an extended concordance correlation coefficient which measures agreement among more than two responses. With these extensions, the generalized concordance correlation coefficient provides a unifying approach to assessing agreement among two or more measures that are either continuous or categorical in scale.
ON TESTING THE EQUALITY OF K MULTIPLEAND PARTIAL CORRELATION COEFFICIENTS
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Coutsourides (1980) derives an ad hoc nuisance parameter removal test for testing the equality of two multiple correlation coefficients of two independent p variate normal populations, under the assumption that a sample of size n is available from each population. He also extends his ad hoc nuisance parameter removal test to the testing of the equality of two multiple correlation matrices. This paper presents likelihood ratio tests for testing the equality of k multiple correlation coefficients, and also k partial correlation coefficients.
Modified Regression Correlation Coefficient for Poisson Regression Model
Kaengthong, Nattacha; Domthong, Uthumporn
2017-09-01
This study gives attention to indicators in predictive power of the Generalized Linear Model (GLM) which are widely used; however, often having some restrictions. We are interested in regression correlation coefficient for a Poisson regression model. This is a measure of predictive power, and defined by the relationship between the dependent variable (Y) and the expected value of the dependent variable given the independent variables [E(Y|X)] for the Poisson regression model. The dependent variable is distributed as Poisson. The purpose of this research was modifying regression correlation coefficient for Poisson regression model. We also compare the proposed modified regression correlation coefficient with the traditional regression correlation coefficient in the case of two or more independent variables, and having multicollinearity in independent variables. The result shows that the proposed regression correlation coefficient is better than the traditional regression correlation coefficient based on Bias and the Root Mean Square Error (RMSE).
Spatial Correlation Coefficient Images for Ultrasonic Detection (Preprint)
2006-07-01
for image formation and detection based on the similarity of adjacent signals. Signal similarity is quantified in terms of the correlation coefficient calculated...between A-scans digitized at adjacent measurement positions. Correlation coefficient images are introduced for visualizing the similarity...beam field with the defect. Correlation coefficient and C-scan images are shown to demonstrate flat-bottom-hole detection in a stainless steel annular
Improvement of Similarity Measure： Pearson Product-Moment Correlation Coefficient
Institute of Scientific and Technical Information of China (English)
LIUYong-suo; MENGQing-hua; CHENRong; WANGJian-song; JIANGShu-min; HUYu-zhu
2004-01-01
Aim To study the reason of the insensitiveness of Pearson preduct-moment correlation coefficient as a similarity measure and the method to improve its sensitivity. Methods Experimental and simulated data sets were used. Results The distribution range of the data sets influences the sensitivity of Pearson product-moment correlation coefficient. Weighted Pearson product-moment correlation coefficient is more sensitive when the range of the data set is large. Conclusion Weighted Pearson product-moment correlation coefficient is necessary when the range of the data set is large.
Confidence intervals for intraclass correlation coefficients in variance components models
Demetrashvili, Nino; Wit, Ernst C; Van Den Heuvel, Edwin R.
2016-01-01
Confidence intervals for intraclass correlation coefficients in agreement studies with continuous outcomes are model-specific and no generic approach exists. This paper provides two generic approaches for intraclass correlation coefficients of the form -' q = 1 Q σ q 2 / (-' q = 1 Q σ q 2 + -' p = Q
A Note on the Correlated Random Coefficient Model
DEFF Research Database (Denmark)
Kolodziejczyk, Christophe
In this note we derive the bias of the OLS estimator for a correlated random coefficient model with one random coefficient, but which is correlated with a binary variable. We provide set-identification to the parameters of interest of the model. We also show how to reduce the bias of the estimator...
Confidence intervals for intraclass correlation coefficients in variance components models
Demetrashvili, Nino; Wit, Ernst C; Van Den Heuvel, Edwin R.
2016-01-01
Confidence intervals for intraclass correlation coefficients in agreement studies with continuous outcomes are model-specific and no generic approach exists. This paper provides two generic approaches for intraclass correlation coefficients of the form -' q = 1 Q σ q 2 / (-' q = 1 Q σ q 2 + -' p = Q
Automatic speech segmentation using throat-acoustic correlation coefficients
Mussabayev, Rustam Rafikovich; Kalimoldayev, Maksat N.; Amirgaliyev, Yedilkhan N.; Mussabayev, Timur R.
2016-11-01
This work considers one of the approaches to the solution of the task of discrete speech signal automatic segmentation. The aim of this work is to construct such an algorithm which should meet the following requirements: segmentation of a signal into acoustically homogeneous segments, high accuracy and segmentation speed, unambiguity and reproducibility of segmentation results, lack of necessity of preliminary training with the use of a special set consisting of manually segmented signals. Development of the algorithm which corresponds to the given requirements was conditioned by the necessity of formation of automatically segmented speech databases that have a large volume. One of the new approaches to the solution of this task is viewed in this article. For this purpose we use the new type of informative features named TAC-coefficients (Throat-Acoustic Correlation coefficients) which provide sufficient segmentation accuracy and effi- ciency.
Use of a Correlation Coefficient for Conditional Averaging.
1997-04-01
data. Selection of the sine function period and a correlation coefficient threshold are discussed. Also examined are the effects of the period and...threshold level on the number of ensembles captured for inclusion for conditional averaging. Both the selection of threshold correlation coefficient and the...A method of collecting ensembles for conditional averaging is presented that uses data collected from a plane mixing layer. The correlation
Diabetic Erythrocytes Test by Correlation Coefficient
Korol, A.M; Foresto, P; Darrigo, M; Rosso, O.A
2008-01-01
Even when a healthy individual is studied, his/her erythrocytes in capillaries continually change their shape in a synchronized erratic fashion. In this work, the problem of characterizing the cell behavior is studied from the perspective of bounded correlated random walk, based on the assumption that diffractometric data involves both deterministic and stochastic components. The photometric readings are obtained by ektacytometry over several millions of shear elongated cells, using a home-made device called Erythrodeformeter. We have only a scalar signal and no governing equations; therefore the complete behavior has to be reconstructed in an artificial phase space. To analyze dynamics we used the technique of time delay coordinates suggested by Takens, May algorithm, and Fourier transform. The results suggest that on random-walk approach the samples from healthy controls exhibit significant differences from those from diabetic patients and these could allow us to claim that we have linked mathematical nonlinear tools with clinical aspects of diabetic erythrocytes’ rheological properties. PMID:19415139
A correlation for heat transfer coefficients in food extruders.
Levine, L; Rockwood, J
1986-06-01
A dimensionless correlation of heat transfer coefficient for heat flow between the extruder barrel wall and extrudate is presented. The standard error of estimate of the correlation is 12.4%. The correlation is useful for the design and scale-up of food extruders and the design of associated temperature control systems.
[Electroencephalogram Feature Selection Based on Correlation Coefficient Analysis].
Zhou, Jinzhi; Tang, Xiaofang
2015-08-01
In order to improve the accuracy of classification with small amount of motor imagery training data on the development of brain-computer interface (BCD systems, we proposed an analyzing method to automatically select the characteristic parameters based on correlation coefficient analysis. Throughout the five sample data of dataset IV a from 2005 BCI Competition, we utilized short-time Fourier transform (STFT) and correlation coefficient calculation to reduce the number of primitive electroencephalogram dimension, then introduced feature extraction based on common spatial pattern (CSP) and classified by linear discriminant analysis (LDA). Simulation results showed that the average rate of classification accuracy could be improved by using correlation coefficient feature selection method than those without using this algorithm. Comparing with support vector machine (SVM) optimization features algorithm, the correlation coefficient analysis can lead better selection parameters to improve the accuracy of classification.
Generalized Correlation Coefficient Based on Log Likelihood Ratio Test Statistic
Directory of Open Access Journals (Sweden)
Liu Hsiang-Chuan
2016-01-01
Full Text Available In this paper, I point out that both Joe’s and Ding’s strength statistics can only be used for testing the pair-wise independence, and I propose a novel G-square based strength statistic, called Liu’s generalized correlation coefficient, it can be used to detect and compare the strength of not only the pair-wise independence but also the mutual independence of any multivariate variables. Furthermore, I proved that only Liu’s generalized correlation coefficient is strictly increasing on its number of variables, it is more sensitive and useful than Cramer’s V coefficient, in other words, Liu generalized correlation coefficient is not only the G-square based strength statistic, but also an improved statistic for detecting and comparing the strengths of deferent associations of any two or more sets of multivariate variables, moreover, this new strength statistic can also be tested by G2.
Overcoming multicollinearity in multiple regression using correlation coefficient
Zainodin, H. J.; Yap, S. J.
2013-09-01
Multicollinearity happens when there are high correlations among independent variables. In this case, it would be difficult to distinguish between the contributions of these independent variables to that of the dependent variable as they may compete to explain much of the similar variance. Besides, the problem of multicollinearity also violates the assumption of multiple regression: that there is no collinearity among the possible independent variables. Thus, an alternative approach is introduced in overcoming the multicollinearity problem in achieving a well represented model eventually. This approach is accomplished by removing the multicollinearity source variables on the basis of the correlation coefficient values based on full correlation matrix. Using the full correlation matrix can facilitate the implementation of Excel function in removing the multicollinearity source variables. It is found that this procedure is easier and time-saving especially when dealing with greater number of independent variables in a model and a large number of all possible models. Hence, in this paper detailed insight of the procedure is shown, compared and implemented.
Genome-scale cluster analysis of replicated microarrays using shrinkage correlation coefficient.
Yao, Jianchao; Chang, Chunqi; Salmi, Mari L; Hung, Yeung Sam; Loraine, Ann; Roux, Stanley J
2008-06-18
correlation coefficient and the SD-weighted correlation coefficient, and is particularly useful for clustering replicated microarray data. This computational approach should be generally useful for proteomic data or other high-throughput analysis methodology.
Genome-scale cluster analysis of replicated microarrays using shrinkage correlation coefficient
Directory of Open Access Journals (Sweden)
Loraine Ann
2008-06-01
This study shows that SCC is an alternative to the Pearson correlation coefficient and the SD-weighted correlation coefficient, and is particularly useful for clustering replicated microarray data. This computational approach should be generally useful for proteomic data or other high-throughput analysis methodology.
Statistical Study of Turbulence: Spectral Functions and Correlation Coefficients
Frenkiel, Francois N.
1958-01-01
In reading the publications on turbulence of different authors, one often runs the risk of confusing the various correlation coefficients and turbulence spectra. We have made a point of defining, by appropriate concepts, the differences which exist between these functions. Besides, we introduce in the symbols a few new characteristics of turbulence. In the first chapter, we study some relations between the correlation coefficients and the different turbulence spectra. Certain relations are given by means of demonstrations which could be called intuitive rather than mathematical. In this way we demonstrate that the correlation coefficients between the simultaneous turbulent velocities at two points are identical, whether studied in Lagrange's or in Euler's systems. We then consider new spectra of turbulence, obtained by study of the simultaneous velocities along a straight line of given direction. We determine some relations between these spectra and the correlation coefficients. Examining the relation between the spectrum of the turbulence measured at a fixed point and the longitudinal-correlation curve given by G. I. Taylor, we find that this equation is exact only when the coefficient is very small.
Someswara Rao, Chinta; Viswanadha Raju, S
2016-03-01
In this paper, we consider correlation coefficient, rank correlation coefficient and cosine similarity measures for evaluating similarity between Homo sapiens and monkeys. We used DNA chromosomes of genome wide genes to determine the correlation between the chromosomal content and evolutionary relationship. The similarity among the H. sapiens and monkeys is measured for a total of 210 chromosomes related to 10 species. The similarity measures of these different species show the relationship between the H. sapiens and monkey. This similarity will be helpful at theft identification, maternity identification, disease identification, etc.
Distributing Correlation Coefficients of Linear Structure-Activity/Property Models
Directory of Open Access Journals (Sweden)
Sorana D. BOLBOACA
2011-12-01
Full Text Available Quantitative structure-activity/property relationships are mathematical relationships linking chemical structure and activity/property in a quantitative manner. These in silico approaches are frequently used to reduce animal testing and risk-assessment, as well as to increase time- and cost-effectiveness in characterization and identification of active compounds. The aim of our study was to investigate the pattern of correlation coefficients distribution associated to simple linear relationships linking the compounds structure with their activities. A set of the most common ordnance compounds found at naval facilities with a limited data set with a range of toxicities on aquatic ecosystem and a set of seven properties was studied. Statistically significant models were selected and investigated. The probability density function of the correlation coefficients was investigated using a series of possible continuous distribution laws. Almost 48% of the correlation coefficients proved fit Beta distribution, 40% fit Generalized Pareto distribution, and 12% fit Pert distribution.
Correlation between satellite vegetation indices and crop coefficients
Russo, A. L.; Simoniello, T.; Greco, M.; Squicciarrino, G.; Lanfredi, M.; Macchiato, M.
2010-05-01
Accurate estimations of plant evapotranspiration and its spatial distribution are fundamental for the evaluation of vegetation water stress. Satellite remote sensing techniques represent precious tools for the evapotranspiration estimations at large scale. Many studies are based on the use of thermal signals as inputs for energy balance equations that are solved to estimate evapotranspiration (e.g., Bastiaanssen et al., 1998; Ayenew, 2003). This approach requires many inputs and a detailed theoretical background knowledge. Other works (e.g., Calera at al., 2005; Gonzalez-Dugo and Mateos, 2008) explored a second approach based on the FAO method that estimates the plant evapotranspiration by weighting the reference evapotranspiration with a crop coefficient (Kc) derived from satellite based vegetation indices. Such studies mainly investigated the usefulness of high resolution satellite data, such as Quickbird, Ikonos, TM, that in spite of the high spatial sampling, are not suitable for a dense temporal sampling. In order to generate spatially distributed values of Kc that capture field-specific crop development, we investigated the usefulness of vegetation indices derived from a time series (2005-2008) of medium resolution MODIS data. We analyzed the spatial and temporal correlation of different indices (NDVI, EVI, and WDVI) with crop coefficients available in literature for different herbaceous and arboreal cultivations present in the study area (Basilicata region, southern Italy). To take into account the background of the cultivation covers, we weighted the Kc by considering the vegetation fraction within each the pixel. By evaluating altogether the cultivations, we found that the correlation increases during the growing season (R2 > 0.80) whereas it decreases during the winter period (R2 cultivation highlighted that NDVI provided quite high correlation for all the investigated cultivation with maximum values for wheat (R2 = 0.89) and vineyards (R2 = 0.83). For
A comparison of two indices for the intraclass correlation coefficient.
Shieh, Gwowen
2012-12-01
In the present study, we examined the behavior of two indices for measuring the intraclass correlation in the one-way random effects model: the prevailing ICC(1) (Fisher, 1938) and the corrected eta-squared (Bliese & Halverson, 1998). These two procedures differ both in their methods of estimating the variance components that define the intraclass correlation coefficient and in their performance of bias and mean squared error in the estimation of the intraclass correlation coefficient. In contrast with the natural unbiased principle used to construct ICC(1), in the present study it was analytically shown that the corrected eta-squared estimator is identical to the maximum likelihood estimator and the pairwise estimator under equal group sizes. Moreover, the empirical results obtained from the present Monte Carlo simulation study across various group structures revealed the mutual dominance relationship between their truncated versions for negative values. The corrected eta-squared estimator performs better than the ICC(1) estimator when the underlying population intraclass correlation coefficient is small. Conversely, ICC(1) has a clear advantage over the corrected eta-squared for medium and large magnitudes of population intraclass correlation coefficient. The conceptual description and numerical investigation provide guidelines to help researchers choose between the two indices for more accurate reliability analysis in multilevel research.
Analysis of correlation coefficient filtering in elasticity imaging.
Huang, Sheng-Wen; Rubin, Jonathan M; Xie, Hua; Witte, Russell S; Jia, Congxian; Olafsson, Ragnar; O'Donnell, Matthew
2008-11-01
Correlation-based speckle tracking methods are commonly used in elasticity imaging to estimate displacements. In the presence of local strain, a larger window size results in larger displacement error. To reduce tracking error, we proposed a short correlation window followed by a correlation coefficient filter. Although simulation and experimental results demonstrated the efficacy of the method, it was not clear why correlation coefficient filtering reduces tracking error since tracking error increases if normalization before filtering is not applied. In this paper, we analyzed tracking errors by estimating phase variances of the cross-correlation function and the correlation coefficient at the true time lag based on statistical properties of these functions' real and imaginary parts. The role of normalization is clarified by identifying the effect of the cross-correlation function's amplitude fluctuation on the function's imaginary part. Furthermore, we present analytic forms for predicting axial displacement error as a function of strain, system parameters (signal-to-noise ratio, center frequency, and signal and noise bandwidths), and tracking parameters (window and filter sizes) for cases with and without normalization before filtering. Simulation results correspond to theory well for both noise-free cases and general cases with an empirical correction term included for strains up to 4%.
A Note on a Geometric Interpretation of the Correlation Coefficient.
Marks, Edmond
1982-01-01
An alternate geometric interpretation of the correlation coefficient to that given in most statistics texts for psychology and education is presented. This interpretation is considered to be more consistent with the statistical model for the data, and richer in geometric meaning. (Author)
Computer Map Typing - Optimizing the Correlation Coefficient Threshold,
the procedures which would be employed in the preparation of each catalog. This paper addresses only one of these questions; ’What correlation ... coefficient threshold provides the best of map types.’ The choice of an appropriate threshold value is, at best, a compromise. This paper shows that a
Highlighting material structure with transmission electron diffraction correlation coefficient maps.
Kiss, Ákos K; Rauch, Edgar F; Lábár, János L
2016-04-01
Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast.
Correlation Revelation: The Search for Meaning in Pearson's Coefficient
Huhn, Craig
2016-01-01
When the author was first charged with getting a group of students to understand the correlation coefficient, he did not anticipate the topic would challenge his own understanding, let alone cause him to eventually question the very nature of mathematics itself. On the surface, the idea seemed straightforward, one that millions of students across…
Modeling Concordance Correlation Coefficient for Longitudinal Study Data
Ma, Yan; Tang, Wan; Yu, Qin; Tu, X. M.
2010-01-01
Measures of agreement are used in a wide range of behavioral, biomedical, psychosocial, and health-care related research to assess reliability of diagnostic test, psychometric properties of instrument, fidelity of psychosocial intervention, and accuracy of proxy outcome. The concordance correlation coefficient (CCC) is a popular measure of…
On the misinterpretation of the correlation coefficient in pharmaceutical sciences
DEFF Research Database (Denmark)
Sonnergaard, Jørn
2006-01-01
The correlation coefficient is often used and more often misused as a universal parameter expressing the quality in linear regression analysis. The popularity of this dimensionless quantity is evident as it is easy to communicate and considered to be unproblematic to comprehend. However, illustra...
National Research Council Canada - National Science Library
Kang, Yusuhn; Choi, Seung Hong; Kim, Young-Jae; Kim, Kwang Gi; Sohn, Chul-Ho; Kim, Ji-Hoon; Yun, Tae Jin; Chang, Kee-Hyun
2011-01-01
To explore the role of histogram analysis of apparent diffusion coefficient (ADC) maps based on entire tumor volume data in determining glioma grade and to evaluate the diagnostic performance of ADC maps at standard...
Comparing two K-category assignments by a K-category correlation coefficient
DEFF Research Database (Denmark)
Gorodkin, Jan
2004-01-01
Predicted assignments of biological sequences are often evaluated by Matthews correlation coefficient. However, Matthews correlation coefficient applies only to cases where the assignments belong to two categories, and cases with more than two categories are often artificially forced into two...... categories by considering what belongs and what does not belong to one of the categories, leading to the loss of information. Here, an extended correlation coefficient that applies to K-categories is proposed, and this measure is shown to be highly applicable for evaluating prediction of RNA secondary...
Chu, De-Ren; Zhou, Qun; Yu, Lu; Sun, Su-Qin
2007-09-01
Based on the fingerprint infrared spectrum database, array of correlation coefficient has been first applied to identify traditional Chinese medicine slviae miltiorrhizae Bge. from different producing areas and growing environments. The result showed that the setting of high correlation coefficient in particular ranges of spectrum could differentiate the producing area of Slviae, while the setting of low correlation coefficient threshold of R5 to R7 ranges could identify wild or cultivated samples. This approach seems to be not only a simple but also an accurate method for identifying the character of different Slviae.
Diagnosing cysts with correlation coefficient images from 2-dimensional freehand elastography.
Booi, Rebecca C; Carson, Paul L; O'Donnell, Matthew; Richards, Michael S; Rubin, Jonathan M
2007-09-01
We compared the diagnostic potential of using correlation coefficient images versus elastograms from 2-dimensional (2D) freehand elastography to characterize breast cysts. In this preliminary study, which was approved by the Institutional Review Board and compliant with the Health Insurance Portability and Accountability Act, we imaged 4 consecutive human subjects (4 cysts, 1 biopsy-verified benign breast parenchyma) with freehand 2D elastography. Data were processed offline with conventional 2D phase-sensitive speckle-tracking algorithms. The correlation coefficient in the cyst and surrounding tissue was calculated, and appearances of the cysts in the correlation coefficient images and elastograms were compared. The correlation coefficient in the cysts was considerably lower (14%-37%) than in the surrounding tissue because of the lack of sufficient speckle in the cysts, as well as the prominence of random noise, reverberations, and clutter, which decorrelated quickly. Thus, the cysts were visible in all correlation coefficient images. In contrast, the elastograms associated with these cysts each had different elastographic patterns. The solid mass in this study did not have the same high decorrelation rate as the cysts, having a correlation coefficient only 2.1% lower than that of surrounding tissue. Correlation coefficient images may produce a more direct, reliable, and consistent method for characterizing cysts than elastograms.
Estimating the generalized concordance correlation coefficient through variance components.
Carrasco, Josep L; Jover, Lluís
2003-12-01
The intraclass correlation coefficient (ICC) and the concordance correlation coefficient (CCC) are two of the most popular measures of agreement for variables measured on a continuous scale. Here, we demonstrate that ICC and CCC are the same measure of agreement estimated in two ways: by the variance components procedure and by the moment method. We propose estimating the CCC using variance components of a mixed effects model, instead of the common method of moments. With the variance components approach, the CCC can easily be extended to more than two observers, and adjusted using confounding covariates, by incorporating them in the mixed model. A simulation study is carried out to compare the variance components approach with the moment method. The importance of adjusting by confounding covariates is illustrated with a case example.
A short note on jackknifing the concordance correlation coefficient.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2014-02-10
Lin's concordance correlation coefficient (CCC) is a very popular scaled index of agreement used in applied statistics. To obtain a confidence interval (CI) for the estimate of CCC, jackknifing was proposed and shown to perform well in simulation as well as in applications. However, a theoretical proof of the validity of the jackknife CI for the CCC has not been presented yet. In this note, we establish a sufficient condition for using the jackknife method to construct the CI for the CCC.
Apparent diffusion coefficient correlation with oesophageal tumour stroma and angiogenesis
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Aoyagi, Tomoyoshi; Shuto, Kiyohiko; Okazumi, Shinichi; Hayano, Kohichi; Satoh, Asami; Saitoh, Hiroshige; Shimada, Hideaki; Nabeya, Yoshihiro; Matsubara, Hisahiro [Chiba University, Department of Frontier Surgery, Graduate School of Medicine, Chiba (Japan); Kazama, Toshiki [Chiba University, Department of Radiology, Graduate School of Medicine, Chiba (Japan)
2012-06-15
Because diffusion-weighted imaging (DWI) can predict the prognosis of patients with oesophageal squamous cell carcinoma (ESCC), we hypothesised that apparent diffusion coefficient (ADC) values might be correlated with the collagen content and tumour angiogenesis. The purpose of this study was to determine the correlation between ADC values of ESCC before treatment and oesophageal tumour stroma and angiogenesis. Seventeen patients with ESCC were enrolled. The ADC values were calculated from the DWI score. Seventeen patients who had undergone oesophagectomy were analysed for tumour stroma, vascular endothelial growth factor (VEGF) and CD34. Tissue collagen was stained with azocarmine and aniline blue to quantitatively analyse the extracellular matrix in cancer stroma. Tissues were stained with VEGF and CD34 to analyse the angiogenesis. The ADC values decreased with stromal collagen growth. We found a negative correlation between the tumour ADC and the amount of stromal collagen (r = -0.729, P = 0.001), i.e. the ADC values decreased with growth of VEGF. We also found a negative correlation between the ADC of the tumours and the amount of VEGF (r = 0.538, P = 0.026). Our results indicated that the ADC value may be a novel prognostic factor and contribute to the treatment of oesophageal cancer. circle Magnetic resonance apparent diffusion coefficient values inversely indicate tumour stromal collagen circle There is also negative correlation between ADCs and vascular endothelial growth factor circle ADC values may contribute to the treatment of oesophageal cancer. (orig.)
Apparent diffusion coefficient correlation with oesophageal tumour stroma and angiogenesis.
Aoyagi, Tomoyoshi; Shuto, Kiyohiko; Okazumi, Shinichi; Hayano, Kohichi; Satoh, Asami; Saitoh, Hiroshige; Shimada, Hideaki; Nabeya, Yoshihiro; Kazama, Toshiki; Matsubara, Hisahiro
2012-06-01
Because diffusion-weighted imaging (DWI) can predict the prognosis of patients with oesophageal squamous cell carcinoma (ESCC), we hypothesised that apparent diffusion coefficient (ADC) values might be correlated with the collagen content and tumour angiogenesis. The purpose of this study was to determine the correlation between ADC values of ESCC before treatment and oesophageal tumour stroma and angiogenesis. Seventeen patients with ESCC were enrolled. The ADC values were calculated from the DWI score. Seventeen patients who had undergone oesophagectomy were analysed for tumour stroma, vascular endothelial growth factor (VEGF) and CD34. Tissue collagen was stained with azocarmine and aniline blue to quantitatively analyse the extracellular matrix in cancer stroma. Tissues were stained with VEGF and CD34 to analyse the angiogenesis. The ADC values decreased with stromal collagen growth. We found a negative correlation between the tumour ADC and the amount of stromal collagen (r = -0.729, P = 0.001), i.e. the ADC values decreased with growth of VEGF. We also found a negative correlation between the ADC of the tumours and the amount of VEGF (r = 0.538, P = 0.026). Our results indicated that the ADC value may be a novel prognostic factor and contribute to the treatment of oesophageal cancer. • Magnetic resonance apparent diffusion coefficient values inversely indicate tumour stromal collagen • There is also negative correlation between ADCs and vascular endothelial growth factor • ADC values may contribute to the treatment of oesophageal cancer.
Generalization of Clustering Coefficients to Signed Correlation Networks
Costantini, Giulio; Perugini, Marco
2014-01-01
The recent interest in network analysis applications in personality psychology and psychopathology has put forward new methodological challenges. Personality and psychopathology networks are typically based on correlation matrices and therefore include both positive and negative edge signs. However, some applications of network analysis disregard negative edges, such as computing clustering coefficients. In this contribution, we illustrate the importance of the distinction between positive and negative edges in networks based on correlation matrices. The clustering coefficient is generalized to signed correlation networks: three new indices are introduced that take edge signs into account, each derived from an existing and widely used formula. The performances of the new indices are illustrated and compared with the performances of the unsigned indices, both on a signed simulated network and on a signed network based on actual personality psychology data. The results show that the new indices are more resistant to sample variations in correlation networks and therefore have higher convergence compared with the unsigned indices both in simulated networks and with real data. PMID:24586367
Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan
2013-09-01
In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.
Matrix-based concordance correlation coefficient for repeated measures.
Hiriote, Sasiprapa; Chinchilli, Vernon M
2011-09-01
In many clinical studies, Lin's concordance correlation coefficient (CCC) is a common tool to assess the agreement of a continuous response measured by two raters or methods. However, the need for measures of agreement may arise for more complex situations, such as when the responses are measured on more than one occasion by each rater or method. In this work, we propose a new CCC in the presence of repeated measurements, called the matrix-based concordance correlation coefficient (MCCC) based on a matrix norm that possesses the properties needed to characterize the level of agreement between two p× 1 vectors of random variables. It can be shown that the MCCC reduces to Lin's CCC when p= 1. For inference, we propose an estimator for the MCCC based on U-statistics. Furthermore, we derive the asymptotic distribution of the estimator of the MCCC, which is proven to be normal. The simulation studies confirm that overall in terms of accuracy, precision, and coverage probability, the estimator of the MCCC works very well in general cases especially when n is greater than 40. Finally, we use real data from an Asthma Clinical Research Network (ACRN) study and the Penn State Young Women's Health Study for demonstration.
Belteki, Gusztav; Lin, Benjamin; Morley, Colin J
2017-10-01
Carbon-dioxide elimination during high-frequency oscillatory ventilation (HFOV) is thought to be proportional to the carbon dioxide diffusion coefficient (DCO2 ) which is calculated as frequency x (tidal volume)(2) . DCO2 can be used to as an indicator of CO2 elimination but values obtained in different patients cannot be directly compared. To analyze the relationship between DCO2 , the weight-corrected DCO2 (DCO2 corr) and blood gas PCO2 values obtained from infants receiving HFOV. DCO2 data were obtained from 14 infants at 1/s sampling rate and the mean DCO2 was determined over 10 min periods preceding the time of the blood gas. DCO2 corr was calculated by dividing the DCO2 by the square of the body weight in kg. Weight-correction significantly reduced the inter-individual variability of DCO2 . When data from all the babies were combined, standard DCO2 showed no correlation with PCO2 but DCO2 corr showed a weak but statistically significant inverse correlation. The correlation was better when the endotracheal leak was 50 mL(2) /sec/kg(2) or VThf > 2.5 mL/kg was rarely needed to avoid hypercapnia. Weight-correction of DCO2 values improved its comparability between patients. Weight-corrected DCO2 correlated better with PCO2 than uncorrected DCO2 but the correlation was weak. © 2017 Wiley Periodicals, Inc.
Akataki, K; Mita, K; Itoh, Y
1999-01-01
The within-day and between-day repeatability of the mechanomyogram (MMG) was assessed using the coefficient of variation (CV) and the intraclass correlation coefficient (ICC) and was compared with that of the electromyogram (EMG). The MMG and EMG were recorded simultaneously during isometric elbow flexion trials at different submaximal levels of 10% to 90% MVC. The testing session consisting of 9 submaximal trials was repeated 8 times on the same day for estimation of the within-day variation. In order to examine the between-day variation, the same testing session was also performed 8 times over 3 weeks with a 2-day rest interval between each session. The CVs within-day and between-day in both the MMG and EMG did not demonstrate any significant differences relating to the magnitude of force exerted. The CVs combined over all the force levels were approximately 10% within the same day and 25% between days for both the MMG and EMG. These corresponded to the within-day ICC of approximately 0.95 and the between-day ICC of 0.80. The repeatability of the MMG during submaximal isometric contractions of biceps brachii muscles is considered to be similar to that of the more established EMG.
A robust bayesian estimate of the concordance correlation coefficient.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2015-01-01
A need for assessment of agreement arises in many situations including statistical biomarker qualification or assay or method validation. Concordance correlation coefficient (CCC) is one of the most popular scaled indices reported in evaluation of agreement. Robust methods for CCC estimation currently present an important statistical challenge. Here, we propose a novel Bayesian method of robust estimation of CCC based on multivariate Student's t-distribution and compare it with its alternatives. Furthermore, we extend the method to practically relevant settings, enabling incorporation of confounding covariates and replications. The superiority of the new approach is demonstrated using simulation as well as real datasets from biomarker application in electroencephalography (EEG). This biomarker is relevant in neuroscience for development of treatments for insomnia.
Correlation Coefficients: Mean Bias and Confidence Interval Distortions
Directory of Open Access Journals (Sweden)
Richard L. Gorsuch
2011-05-01
Full Text Available Non-zero correlation coefficients have non-normal distributions, affecting both means and standard deviations. Previous research suggests that z transformation may effectively correct mean bias for N's less than 30. In this study, simulations with small (20 and 30 and large (50 and 100 N's found that mean bias adjustments for larger N's are seldom needed. However, z transformations improved confidence intervals even for N = 100. The improvement was not in the estimated standard errors so much as in the asymmetrical CI's estimates based upon the z transformation. The resulting observed probabilities were generally accurate to within 1 point in the first non-zero digit. These issues are an order of magnitude less important for accuracy than design issues influencing the accuracy of the results, such as reliability, restriction of range, and N. DOI: 10.2458/azu_jmmss.v1i2.114
Liu, Yongsuo; Meng, Qinghua; Chen, Rong; Wang, Jiansong; Jiang, Shumin; Hu, Yuzhu
2004-01-01
The Pearson product-moment correlation coefficient is being used to evaluate the similarity of the high-performance liquid chromatographic fingerprints of traditional Chinese medicine (TCM) in China. It is confirmed that a large range of peak areas produced the wrong results. A new algorithm concerning weighted Pearson product-moment correlation coefficient is proposed in this article. The results for both real cases and simulated data sets show that the weighted Pearson product-moment correlation coefficients allow relatively larger differences for large values, smaller differences for small values, and more reliable results than the unweighted Pearson product-moment correlation coefficients. Weight selection depends on the specific scientific problem.
Bivariate correlation coefficients in family-type clustered studies.
Luo, Jingqin; D'Angela, Gina; Gao, Feng; Ding, Jimin; Xiong, Chengjie
2015-11-01
We propose a unified approach based on a bivariate linear mixed effects model to estimate three types of bivariate correlation coefficients (BCCs), as well as the associated variances between two quantitative variables in cross-sectional data from a family-type clustered design. These BCCs are defined at different levels of experimental units including clusters (e.g., families) and subjects within clusters and assess different aspects on the relationships between two variables. We study likelihood-based inferences for these BCCs, and provide easy implementation using standard software SAS. Unlike several existing BCC estimators in the literature on clustered data, our approach can seamlessly handle two major analytic challenges arising from a family-type clustered design: (1) many families may consist of only one single subject; (2) one of the paired measurements may be missing for some subjects. Hence, our approach maximizes the use of data from all subjects (even those missing one of the two variables to be correlated) from all families, regardless of family size. We also conduct extensive simulations to show that our estimators are superior to existing estimators in handling missing data or/and imbalanced family sizes and the proposed Wald test maintains good size and power for hypothesis testing. Finally, we analyze a real-world Alzheimer's disease dataset from a family clustered study to investigate the BCCs across different modalities of disease markers including cognitive tests, cerebrospinal fluid biomarkers, and neuroimaging biomarkers.
Statistical functions and relevant correlation coefficients of clearness index
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.
A problem with the correlation coefficient as a measure of gene expression divergence.
Pereira, Vini; Waxman, David; Eyre-Walker, Adam
2009-12-01
The correlation coefficient is commonly used as a measure of the divergence of gene expression profiles between different species. Here we point out a potential problem with this statistic: if measurement error is large relative to the differences in expression, the correlation coefficient will tend to show high divergence for genes that have relatively uniform levels of expression across tissues or time points. We show that genes with a conserved uniform pattern of expression have significantly higher levels of expression divergence, when measured using the correlation coefficient, than other genes, in a data set from mouse, rat, and human. We also show that the Euclidean distance yields low estimates of expression divergence for genes with a conserved uniform pattern of expression.
Comparing two K-category assignments by a K-category correlation coefficient.
Gorodkin, J
2004-12-01
Predicted assignments of biological sequences are often evaluated by Matthews correlation coefficient. However, Matthews correlation coefficient applies only to cases where the assignments belong to two categories, and cases with more than two categories are often artificially forced into two categories by considering what belongs and what does not belong to one of the categories, leading to the loss of information. Here, an extended correlation coefficient that applies to K-categories is proposed, and this measure is shown to be highly applicable for evaluating prediction of RNA secondary structure in cases where some predicted pairs go into the category "unknown" due to lack of reliability in predicted pairs or unpaired residues. Hence, predicting base pairs of RNA secondary structure can be a three-category problem. The measure is further shown to be well in agreement with existing performance measures used for ranking protein secondary structure predictions. Server and software is available at http://rk.kvl.dk/.
Feng, Dai; Svetnik, Vladimir; Coimbra, Alexandre; Baumgartner, Richard
2014-01-01
The intraclass correlation coefficient (ICC) with fixed raters or, equivalently, the concordance correlation coefficient (CCC) for continuous outcomes is a widely accepted aggregate index of agreement in settings with small number of raters. Quantifying the precision of the CCC by constructing its confidence interval (CI) is important in early drug development applications, in particular in qualification of biomarker platforms. In recent years, there have been several new methods proposed for construction of CIs for the CCC, but their comprehensive comparison has not been attempted. The methods consisted of the delta method and jackknifing with and without Fisher's Z-transformation, respectively, and Bayesian methods with vague priors. In this study, we carried out a simulation study, with data simulated from multivariate normal as well as heavier tailed distribution (t-distribution with 5 degrees of freedom), to compare the state-of-the-art methods for assigning CI to the CCC. When the data are normally distributed, the jackknifing with Fisher's Z-transformation (JZ) tended to provide superior coverage and the difference between it and the closest competitor, the Bayesian method with the Jeffreys prior was in general minimal. For the nonnormal data, the jackknife methods, especially the JZ method, provided the coverage probabilities closest to the nominal in contrast to the others which yielded overly liberal coverage. Approaches based upon the delta method and Bayesian method with conjugate prior generally provided slightly narrower intervals and larger lower bounds than others, though this was offset by their poor coverage. Finally, we illustrated the utility of the CIs for the CCC in an example of a wake after sleep onset (WASO) biomarker, which is frequently used in clinical sleep studies of drugs for treatment of insomnia.
Speed Estimation in Geared Wind Turbines Using the Maximum Correlation Coefficient
DEFF Research Database (Denmark)
Skrimpas, Georgios Alexandros; Marhadi, Kun S.; Jensen, Bogi Bech;
2015-01-01
to overcome the above mentioned issues. The high speed stage shaft angular velocity is calculated based on the maximum correlation coefficient between the 1 st gear mesh frequency of the last gearbox stage and a pure sinus tone of known frequency and phase. The proposed algorithm utilizes vibration signals...
A simple approximation to the bivariate normal distribution with large correlation coefficient
Albers, Willem; Kallenberg, Wilbert C.M.
1994-01-01
The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the er
A simple approximation to the bivariate normal distribution with large correlation coefficient
Albers, Willem/Wim; Kallenberg, W.C.M.
1994-01-01
The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the
Liu, An-Nuo; Wang, Lu-Lu; Li, Hui-Ping; Gong, Juan; Liu, Xiao-Hong
2016-11-22
The literature on posttraumatic growth (PTG) is burgeoning, with the inconsistencies in the literature of the relationship between PTG and posttraumatic stress disorder (PTSD) symptoms becoming a focal point of attention. Thus, this meta-analysis aims to explore the relationship between PTG and PTSD symptoms through the Pearson correlation coefficient. A systematic search of the literature from January 1996 to November 2015 was completed. We retrieved reports on 63 studies that involved 26,951 patients. The weighted correlation coefficient revealed an effect size of 0.22 with a 95% confidence interval of 0.18 to 0.25. Meta-analysis provides evidence that PTG may be positively correlated with PTSD symptoms and that this correlation may be modified by age, trauma type, and time since trauma. Accordingly, people with high levels of PTG should not be ignored, but rather, they should continue to receive help to alleviate their PTSD symptoms.
van de Wassenberg, Wilma J G; van der Hoeven, Johannes H; Leenders, Klaus L; Maurits, Natasha M
2008-06-01
Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in cortical sensory processing. We developed and evaluated a new technique to quantify interhemispheric SEP symmetry that uses a time interval including multiple SEP components, measures similarity of SEP waveforms between both hemispheres and results in high symmetry values even in the presence of small interhemispheric anatomic differences. Median nerve SEPs were recorded in 50 healthy subjects (20-70 years) using 128-channel EEG. Symmetry was quantified by the intraclass correlation coefficient and correlation coefficient between global field power of left and right median nerve SEPs. In 74% of subjects left-right intraclass correlation coefficient was higher than 0.60, implying high SEP hemispheric symmetry in terms of shape and amplitude. Left-right intraclass correlation coefficients lower than 0.60 were due to differences in amplitude, unilateral absence of peaks, or shape differences. We quantified SEP waveform interhemispheric symmetry and found it to be high in most healthy subjects. This technique may therefore be useful for detection of unilateral abnormalities in cortical sensory processing.
Parametric image alignment using enhanced correlation coefficient maximization.
Evangelidis, Georgios D; Psarakis, Emmanouil Z
2008-10-01
In this work we propose the use of a modified version of the correlation coefficient as a performance criterion for the image alignment problem. The proposed modification has the desirable characteristic of being invariant with respect to photometric distortions. Since the resulting similarity measure is a nonlinear function of the warp parameters, we develop two iterative schemes for its maximization, one based on the forward additive approach and the second on the inverse compositional method. As it is customary in iterative optimization, in each iteration, the nonlinear objective function is approximated by an alternative expression for which the corresponding optimization is simple. In our case we propose an efficient approximation that leads to a closed-form solution (per iteration) which is of low computational complexity, the latter property being particularly strong in our inverse version. The proposed schemes are tested against the Forward Additive Lucas-Kanade and the Simultaneous Inverse Compositional (SIC) algorithm through simulations. Under noisy conditions and photometric distortions, our forward version achieves more accurate alignments and exhibits faster convergence whereas our inverse version has similar performance as the SIC algorithm but at a lower computational complexity.
Covariate-adjusted confidence interval for the intraclass correlation coefficient.
Shoukri, Mohamed M; Donner, Allan; El-Dali, Abdelmoneim
2013-09-01
A crucial step in designing a new study is to estimate the required sample size. For a design involving cluster sampling, the appropriate sample size depends on the so-called design effect, which is a function of the average cluster size and the intracluster correlation coefficient (ICC). It is well-known that under the framework of hierarchical and generalized linear models, a reduction in residual error may be achieved by including risk factors as covariates. In this paper we show that the covariate design, indicating whether the covariates are measured at the cluster level or at the within-cluster subject level affects the estimation of the ICC, and hence the design effect. Therefore, the distinction between these two types of covariates should be made at the design stage. In this paper we use the nested-bootstrap method to assess the accuracy of the estimated ICC for continuous and binary response variables under different covariate structures. The codes of two SAS macros are made available by the authors for interested readers to facilitate the construction of confidence intervals for the ICC. Moreover, using Monte Carlo simulations we evaluate the relative efficiency of the estimators and evaluate the accuracy of the coverage probabilities of a 95% confidence interval on the population ICC. The methodology is illustrated using a published data set of blood pressure measurements taken on family members.
Optimal classifier for imbalanced data using Matthews Correlation Coefficient metric.
Boughorbel, Sabri; Jarray, Fethi; El-Anbari, Mohammed
2017-01-01
Data imbalance is frequently encountered in biomedical applications. Resampling techniques can be used in binary classification to tackle this issue. However such solutions are not desired when the number of samples in the small class is limited. Moreover the use of inadequate performance metrics, such as accuracy, lead to poor generalization results because the classifiers tend to predict the largest size class. One of the good approaches to deal with this issue is to optimize performance metrics that are designed to handle data imbalance. Matthews Correlation Coefficient (MCC) is widely used in Bioinformatics as a performance metric. We are interested in developing a new classifier based on the MCC metric to handle imbalanced data. We derive an optimal Bayes classifier for the MCC metric using an approach based on Frechet derivative. We show that the proposed algorithm has the nice theoretical property of consistency. Using simulated data, we verify the correctness of our optimality result by searching in the space of all possible binary classifiers. The proposed classifier is evaluated on 64 datasets from a wide range data imbalance. We compare both classification performance and CPU efficiency for three classifiers: 1) the proposed algorithm (MCC-classifier), the Bayes classifier with a default threshold (MCC-base) and imbalanced SVM (SVM-imba). The experimental evaluation shows that MCC-classifier has a close performance to SVM-imba while being simpler and more efficient.
Bayesian Concordance Correlation Coefficient with Application to Repeatedly Measured Data
Directory of Open Access Journals (Sweden)
Atanu BHATTACHARJEE
2015-10-01
Full Text Available Objective: In medical research, Lin's classical concordance correlation coefficient (CCC is frequently applied to evaluate the similarity of the measurements produced by different raters or methods on the same subjects. It is particularly useful for continuous data. The objective of this paper is to propose the Bayesian counterpart to compute CCC for continuous data. Material and Methods: A total of 33 patients of astrocytoma brain treated in the Department of Radiation Oncology at Malabar Cancer Centre is enrolled in this work. It is a continuous data of tumor volume and tumor size repeatedly measured during baseline pretreatment workup and post surgery follow-ups for all patients. The tumor volume and tumor size are measured separately by MRI and CT scan. The agreement of measurement between MRI and CT scan is calculated through CCC. The statistical inference is performed through Markov Chain Monte Carlo (MCMC technique. Results: Bayesian CCC is found suitable to get prominent evidence for test statistics to explore the relation between concordance measurements. The posterior mean estimates and 95% credible interval of CCC on tumor size and tumor volume are observed with 0.96(0.87,0.99 and 0.98(0.95,0.99 respectively. Conclusion: The Bayesian inference is adopted for development of the computational algorithm. The approach illustrated in this work provides the researchers an opportunity to find out the most appropriate model for specific data and apply CCC to fulfill the desired hypothesis.
Correlation of Cadmium Distribution Coefficients to Soil Characteristics
DEFF Research Database (Denmark)
Holm, Peter Engelund; Rootzen, Helle; Borggaard, Ole K.;
2003-01-01
on whole soil samples have shown that pH is the main parameter controlling the distribution. To identify further the components that are important for Cd binding in soil we measured Cd distribution coefficients (K-d) at two fixed pH values and at low Cd loadings for 49 soils sampled in Denmark. The Kd...... that the organic carbon content was a significant variable at both pH values. Cation exchange capacity (CEC) and gibbsite were important at the low pH (5.3) while iron oxides also were important at the high pH (6.7). None of the other clay minerals present in the soils (illite, smectite, kaolinite, hydroxy......Cadmium (Cd) distribution between the soil solid phase and the soil solution is a key issue in assessing the environmental effect of Cd in the terrestrial environmental. Previous studies have shown that many individual minerals and other components found in soils can bind Cd, but most studies...
Spatially varying cross-correlation coefficients in the presence of nugget effects
Kleiber, William
2012-11-29
We derive sufficient conditions for the cross-correlation coefficient of a multivariate spatial process to vary with location when the spatial model is augmented with nugget effects. The derived class is valid for any choice of covariance functions, and yields substantial flexibility between multiple processes. The key is to identify the cross-correlation coefficient matrix with a contraction matrix, which can be either diagonal, implying a parsimonious formulation, or a fully general contraction matrix, yielding greater flexibility but added model complexity. We illustrate the approach with a bivariate minimum and maximum temperature dataset in Colorado, allowing the two variables to be positively correlated at low elevations and nearly independent at high elevations, while still yielding a positive definite covariance matrix. © 2012 Biometrika Trust.
Directory of Open Access Journals (Sweden)
Reddivenkatagari Subbarama Krishna Reddy
2013-06-01
Full Text Available One hundred germplasm lines of okra (Abelmoschus esculentus (L. Moench were evaluated in a randomized block design with two replications at the Vegetable Research Station, Rajendranagar, Hyderabad, Andhra Pradesh, India, during kharif, 2008. Correlation and path coefficient analysis were carried out to study the character association and contribution, respectively, for thirteen quantitative characters, namely plant height (cm, number of branches per plant, internodal length(cm, days to 50% flowering, first flowering node, first fruiting node, fruit length (cm, fruit width (cm, fruit weight (g, total number of fruits per plant, number of marketable fruits per plant, total yield per plant (g and marketable yield per plant (g for the identification of appropriate selection indices. Phenotypic and genotypic correlation coefficient analysis revealed that plant height, fruit length, fruit width, fruit weight, total number of fruits per plant, number of marketable fruits per plant and total yield per plant had significant positive correlation, while number of branches per plant, internodal length, days to 50% flowering, first flowering node and first fruiting node had significant negative correlation with marketable yield per plant.Genotypic path coefficient analysis revealed that fruit weight, total number of fruits per plant and number of marketable fruits per plant had positively high direct effect on marketable pod yield per plant. Correlation and path coefficient analyses revealed that fruit weight, total number of fruits per plant and number of marketable fruits per plant not only had positively significant association with marketable pod yield per plant, but also had positively high direct effect on marketable pod yield per plant and are regarded as the main determinants of marketable pod yield per plant. The improvement in marketable pod yield per plant will be efficient, if the selection is based on fruit weight, total number of fruits per
Energy Technology Data Exchange (ETDEWEB)
Herranz, J.; Bloxom, S.R.; Keeler, J.B.; Roth, S.R.
1975-12-17
In the proposed Molten Salt Breeder Reactor flowsheet, a fraction of the rare earth fission products is removed from the fuel salt in mass transfer cells. To obtain design parameters for this extraction, the effect of cell size, blade diameter, phase volume, and agitation rate on the mass transfer for a high density ratio system (mercury/water) in nondispersing square cross section contactors was determined. Aqueous side mass transfer coefficients were measured by polarography over a wide range of operating conditions. Correlations for the experimental mass transfer coefficients as functions of the operating parameters are presented. Several techniques for measuring mercury-side mass transfer coefficients were evaluated and a new one is recommended. (auth)
Generalized Correlation Coefficient for Non-Parametric Analysis of Microarray Time-Course Data.
Tan, Qihua; Thomassen, Mads; Burton, Mark; Mose, Kristian Fredløv; Andersen, Klaus Ejner; Hjelmborg, Jacob; Kruse, Torben
2017-06-06
Modeling complex time-course patterns is a challenging issue in microarray study due to complex gene expression patterns in response to the time-course experiment. We introduce the generalized correlation coefficient and propose a combinatory approach for detecting, testing and clustering the heterogeneous time-course gene expression patterns. Application of the method identified nonlinear time-course patterns in high agreement with parametric analysis. We conclude that the non-parametric nature in the generalized correlation analysis could be an useful and efficient tool for analyzing microarray time-course data and for exploring the complex relationships in the omics data for studying their association with disease and health.
Generalized Correlation Coefficient for Non-Parametric Analysis of Microarray Time-Course Data
DEFF Research Database (Denmark)
Tan, Qihua; Thomassen, Mads; Burton, Mark
2017-01-01
Modeling complex time-course patterns is a challenging issue in microarray study due to complex gene expression patterns in response to the time-course experiment. We introduce the generalized correlation coefficient and propose a combinatory approach for detecting, testing and clustering...... the heterogeneous time-course gene expression patterns. Application of the method identified nonlinear time-course patterns in high agreement with parametric analysis. We conclude that the non-parametric nature in the generalized correlation analysis could be an useful and efficient tool for analyzing microarray...... time-course data and for exploring the complex relationships in the omics data for studying their association with disease and health....
Generalized Correlation Coefficient for Non-Parametric Analysis of Microarray Time-Course Data
DEFF Research Database (Denmark)
Tan, Qihua; Thomassen, Mads; Burton, Mark
2017-01-01
Modeling complex time-course patterns is a challenging issue in microarray study due to complex gene expression patterns in response to the time-course experiment. We introduce the generalized correlation coefficient and propose a combinatory approach for detecting, testing and clustering...... the heterogeneous time-course gene expression patterns. Application of the method identified nonlinear time-course patterns in high agreement with parametric analysis. We conclude that the non-parametric nature in the generalized correlation analysis could be an useful and efficient tool for analyzing microarray...
Correlation and path coefficient analysis in coconut (Cocos nucifera L.
Directory of Open Access Journals (Sweden)
S. Geethanjali, D. Rajkumar and N.Shoba
2014-12-01
Full Text Available A total of 43 coconut germplasm accessions were characterized for nut yield and fruit component traits. Correlation analysis showed that most of the fruit traits viz., fruit length, fruit breadth, fruit weight, nut weight, kernel weight and copra weight per nut were positively correlated with each other but showed significant negative correlation with the number of nuts produced per palm per annum. Shell thickness and husk thickness were not correlated with any of the fruit component traits. Path analysis revealed that nut yield and copra content per nut had positive direct effect on the total copra yield per palm. The results of this study showed that equal consideration should be given for both nut yield and copra content per nut while selecting elite genotypes for dual purpose viz., tender nut or culinary use and copra for oil extraction.
Mikuni, Shintaro; Yamamoto, Johtaro; Horio, Takashi; Kinjo, Masataka
2017-08-25
The glucocorticoid receptor (GR) is a transcription factor, which interacts with DNA and other cofactors to regulate gene transcription. Binding to other partners in the cell nucleus alters the diffusion properties of GR. Raster image correlation spectroscopy (RICS) was applied to quantitatively characterize the diffusion properties of EGFP labeled human GR (EGFP-hGR) and its mutants in the cell nucleus. RICS is an image correlation technique that evaluates the spatial distribution of the diffusion coefficient as a diffusion map. Interestingly, we observed that the averaged diffusion coefficient of EGFP-hGR strongly and negatively correlated with its transcriptional activities in comparison to that of EGFP-hGR wild type and mutants with various transcriptional activities. This result suggests that the decreasing of the diffusion coefficient of hGR was reflected in the high-affinity binding to DNA. Moreover, the hyper-phosphorylation of hGR can enhance the transcriptional activity by reduction of the interaction between the hGR and the nuclear corepressors.
Korendijk, E.J.H.; Moerbeek, M.; Maas, C.J.M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or subject
Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.
Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P
2016-06-01
We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.
Wilson, Celia M.
2010-01-01
Research pertaining to the distortion of the squared canonical correlation coefficient has traditionally been limited to the effects of sampling error and associated correction formulas. The purpose of this study was to compare the degree of attenuation of the squared canonical correlation coefficient under varying conditions of score reliability.…
Korendijk, Elly J. H.; Moerbeek, Mirjam; Maas, Cora J. M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or subject matter knowledge. This initial estimate is likely…
The concordance correlation coefficient for repeated measures estimated by variance components.
Carrasco, Josep L; King, Tonya S; Chinchilli, Vernon M
2009-01-01
The concordance correlation coefficient (CCC) is an index that is commonly used to assess the degree of agreement between observers on measuring a continuous characteristic. Here, a CCC for longitudinal repeated measurements is developed through the appropriate specification of the intraclass correlation coefficient from a variance components linear mixed model. A case example and the results of a simulation study are provided.
Korendijk, E.J.H.; Moerbeek, M.; Maas, C.J.M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or
Korendijk, Elly J. H.; Moerbeek, Mirjam; Maas, Cora J. M.
2010-01-01
In the case of trials with nested data, the optimal allocation of units depends on the budget, the costs, and the intracluster correlation coefficient. In general, the intracluster correlation coefficient is unknown in advance and an initial guess has to be made based on published values or subject matter knowledge. This initial estimate is likely…
Wilson, Celia M.
2010-01-01
Research pertaining to the distortion of the squared canonical correlation coefficient has traditionally been limited to the effects of sampling error and associated correction formulas. The purpose of this study was to compare the degree of attenuation of the squared canonical correlation coefficient under varying conditions of score reliability.…
Tests of Fit Based on the Correlation Coefficient
1990-10-04
function. Regional Conference Series in Appl. Math., 9. Philadelphia: SIAM. 2. Gerlach, B., (1979). A consistent correlation-type goodness-of-fit test; with...the distribution of quadratic forms in normal variables. Biometrika, 48, 419-426. 4. Sarkadi, K., (1975). The consistency of the Shapiro- Francia test
Kilger, Robert; Stuke, Maik
2016-01-01
In this work we performed a detailed analysis on the calculation of 43 critical experiments from 6 experimental series all describing plutonium nitrate in aqueous solution contained in metal spheres. The underlying experimental data is taken from the handbook of the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Working Group. We present our modeling assumptions which were derived from the interpretation of the experimental data and discuss the resulting sensitivity analysis. Although the experiments share some components, the derived correlation coefficients are for many cases statistically not significant. Comparing our findings for the correlation coefficients with available data from the DICE Database we find an agreement for the correlation coefficients due to nuclear data. We also compare our results for the correlation coefficients due to experimental uncertainty. Our findings indicate that for the reliable Determination of correlation coefficients a detailed study of the underl...
Empirical correlations for axial dispersion coefficient and Peclet number in fixed-bed columns.
Rastegar, Seyed Omid; Gu, Tingyue
2017-03-24
In this work, a new correlation for the axial dispersion coefficient was obtained using experimental data in the literature for axial dispersion in fixed-bed columns packed with particles. The Chung and Wen correlation, the De Ligny correlation are two popular empirical correlations. However, the former lacks the molecular diffusion term and the latter does not consider bed voidage. The new axial dispersion coefficient correlation in this work was based on additional experimental data in the literature by considering both molecular diffusion and bed voidage. It is more comprehensive and accurate. The Peclet number correlation from the new axial dispersion coefficient correlation on the average leads to 12% lower Peclet number values compared to the values from the Chung and Wen correlation, and in many cases much smaller than those from the De Ligny correlation. Copyright © 2017 Elsevier B.V. All rights reserved.
Ma, Chuang; Wang, Xiangfeng
2012-09-01
One of the computational challenges in plant systems biology is to accurately infer transcriptional regulation relationships based on correlation analyses of gene expression patterns. Despite several correlation methods that are applied in biology to analyze microarray data, concerns regarding the compatibility of these methods with the gene expression data profiled by high-throughput RNA transcriptome sequencing (RNA-Seq) technology have been raised. These concerns are mainly due to the fact that the distribution of read counts in RNA-Seq experiments is different from that of fluorescence intensities in microarray experiments. Therefore, a comprehensive evaluation of the existing correlation methods and, if necessary, introduction of novel methods into biology is appropriate. In this study, we compared four existing correlation methods used in microarray analysis and one novel method called the Gini correlation coefficient on previously published microarray-based and sequencing-based gene expression data in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). The comparisons were performed on more than 11,000 regulatory relationships in Arabidopsis, including 8,929 pairs of transcription factors and target genes. Our analyses pinpointed the strengths and weaknesses of each method and indicated that the Gini correlation can compensate for the shortcomings of the Pearson correlation, the Spearman correlation, the Kendall correlation, and the Tukey's biweight correlation. The Gini correlation method, with the other four evaluated methods in this study, was implemented as an R package named rsgcc that can be utilized as an alternative option for biologists to perform clustering analyses of gene expression patterns or transcriptional network analyses.
Ma, Chuang; Wang, Xiangfeng
2012-01-01
One of the computational challenges in plant systems biology is to accurately infer transcriptional regulation relationships based on correlation analyses of gene expression patterns. Despite several correlation methods that are applied in biology to analyze microarray data, concerns regarding the compatibility of these methods with the gene expression data profiled by high-throughput RNA transcriptome sequencing (RNA-Seq) technology have been raised. These concerns are mainly due to the fact that the distribution of read counts in RNA-Seq experiments is different from that of fluorescence intensities in microarray experiments. Therefore, a comprehensive evaluation of the existing correlation methods and, if necessary, introduction of novel methods into biology is appropriate. In this study, we compared four existing correlation methods used in microarray analysis and one novel method called the Gini correlation coefficient on previously published microarray-based and sequencing-based gene expression data in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). The comparisons were performed on more than 11,000 regulatory relationships in Arabidopsis, including 8,929 pairs of transcription factors and target genes. Our analyses pinpointed the strengths and weaknesses of each method and indicated that the Gini correlation can compensate for the shortcomings of the Pearson correlation, the Spearman correlation, the Kendall correlation, and the Tukey’s biweight correlation. The Gini correlation method, with the other four evaluated methods in this study, was implemented as an R package named rsgcc that can be utilized as an alternative option for biologists to perform clustering analyses of gene expression patterns or transcriptional network analyses. PMID:22797655
Aliya, F; Begum, H; Reddy, M T; Sivaraj, N; Pandravada, S R; Narshimulu, G
2014-05-01
Fifty genotypes of spine gourd (Momordica dioica Roxb.) were evaluated in a randomized block design with two replications at the Vegetable Research Station, Rajendranagar, Hyderabad, Andhra Pradesh, India during kharif, 2012. Correlation and path coefficient analysis were carried out to study the character association and contribution, respectively for twelve quantitative characters namely vine length (m), number of stems per plant, days to first female flower appearance, first female flowering node, days to first fruit harvest, days to last fruit harvest, fruiting period (days), fruit length (cm), fruit width (cm), fruit weight (g), number of fruits per plant and fruit yield per plant (kg) for identification of the potential selection indices. Correlation and path coefficient analyses revealed that fruiting period and number of fruits per plant not only had positively significant correlation with fruit yield but also had positively high direct effect on it and are regarded as the main determinants of fruit yield. Days to first fruit harvest had positively moderate direct effect on fruit yield and its association was negatively significant, days to last fruit harvest had negatively high direct effect on fruit yield and its association was significant positively, hence restricted simultaneous selection can be made for days to first fruit harvest and days to last fruit harvest. The improvement in fruit yield can be effective if selection is based on days to first fruit harvest, days to last fruit harvest, fruiting period and number of fruits per plant.
Directory of Open Access Journals (Sweden)
Hladni Nada
2015-01-01
Full Text Available The most important criteria for introducing new confectionary hybrids into the production is high protein yield. Path coefficient analysis was used to obtain information on direct and indirect effects of studied traits (seed oil content, kernel oil content, seed yield, kernel protein content, mass of 1000 seeds, kernel ratio and hull ratio on protein yield. The research was conducted during three vegetation seasons, on 22 experimental confectionary sunflower hybrids created in the breeding program at the Institute of Field and Vegetable Crops. Strong and very strong correlations were found among the largest number of examined traits. A weak negative interdependence was determined between kernel oil content, kernel protein content, mass of 1000 seeds, hull ratio, and protein yield using the analysis of simple correlation coefficients. Positive but weak correlation was determined between protein yield and seed oil content, and kernel ratio. Very strong positive correlation was determined between protein yield and seed yield (0.468**. The seed oil content had a very strong direct negative effect on protein yield (DE=-0.734**. The mass of 1000 seeds had a weak negative direct effect on protein yield. Kernel protein content and kernel oil content demonstrated a weak direct positive effect on protein yield. Path coefficient analysis of protein yield showed a very strong positive direct effect of kernel ratio (DE=1.340**, seed yield (DE=0.657** and hull ratio (DE=0.992*. These findings confirm the effect of seed yield, kernel ratio, and hull ratio on protein yield, and their importance as the selection criteria in confectionary sunflower breeding. [Projekat Ministarstva nauke Republike Srbije, br. 31025: Development of new varieties and production technology improvement of oil crops for different purposes
Tool for Studying the Effects of Range Restriction in Correlation Coefficient Estimation
1990-07-01
AFHRL-TP-90-6 AIR FORCE TOOL FOR STUDYING THE EFFECTS OF RANGE RESTRICTION IN CORRELATION COEFFICIENT ESTIMATION H U Douglas E. JacksonM Eastern New...the Lftects of kange Restriction in Correlation Coefficient Estimation PE - 62703F PR - 7719 4. AUTHOR(S) TA - 18 Douglas E. Jackson WU - 46 Malcolm J...that one must try to estimate the correlation coefficient between two random variables X and Y in some population P using data taken f-om a
Statistics corner: A guide to appropriate use of correlation coefficient in medical research.
Mukaka, M M
2012-09-01
Correlation is a statistical method used to assess a possible linear association between two continuous variables. It is simple both to calculate and to interpret. However, misuse of correlation is so common among researchers that some statisticians have wished that the method had never been devised at all. The aim of this article is to provide a guide to appropriate use of correlation in medical research and to highlight some misuse. Examples of the applications of the correlation coefficient have been provided using data from statistical simulations as well as real data. Rule of thumb for interpreting size of a correlation coefficient has been provided.
KRIJNEN, WP
1994-01-01
De Vries (1993) discusses Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank-correlation coefficient for assessing the association between the rows of two proximity matrices. For each of these he introduces a weighted average variant and a rowwise variant. In this
KRIJNEN, WP
De Vries (1993) discusses Pearson's product-moment correlation, Spearman's rank correlation, and Kendall's rank-correlation coefficient for assessing the association between the rows of two proximity matrices. For each of these he introduces a weighted average variant and a rowwise variant. In this
Directory of Open Access Journals (Sweden)
Chaumongkol, Y.
2001-11-01
Full Text Available A study of correlation, path coefficient analysis and heritablity for some agronomic characters of oil palm was investigated during February 1998 to January 2002. The oil palm population used in this experiment was derived from F1 tenera hybrids which were collected from various oil palm plantations in Southern Thailand. One good performance bunch (i.e., big bunch, thin shell was selected from each plantation and four to six seeds per selected bunch were used for cultivation. One thousand thirty eight plants were grown at Klong Hoi Khong Research Station, Faculty of Natural Resources, Prince of Songkla University, Songkhla, in 1989. Forty five palms consisted of Dura, Tenera and Pisifera types with 18, 18 and 9 plants respectively, were selected by randomization and tagged for investigation. The oil palm bunch yield and yield component characters were observed from individual palm for 4 years (February 1998 to January 2002. The bunch composition characters were analysed from a single bunch of each palm, sampled between June to October 1999. The results showed that in F2 plants of oil palm, the correlation and the path coefficient between characters relating to oil yield and %oil/bunch varied according to oil palm types (Dura, Tenera and Pisifera. In Dura and Tenera palms, the characters which gave highly positive correlation with a large direct and indirect positive effects on oil yield and %oil/bunch were total bunch weight, %oil/bunch, %fruit/bunch and %oil/fruit. In case of Pisifera palms, the characters which gave highly positive correlation with a large direct and indirect positive effects on oil yield and %oil/bunch were total bunch weight, number of bunches, single bunch weight, %oil/bunch and %fruit/bunch. However, from all investigated characters in F2 plants, only %mesocarp/fruit, %oil/fruit and %fruit/bunch showed the high values of broad sense heritabilities.
Beijeren, H. van; Kehr, K.W.
1986-01-01
The correlation factor, defined as the ratio between the tracer diffusion coefficient in lattice gases and the diffusion coefficient for a corresponding uncorrelated random walk, is known to assume a very simple form under certain conditions. A simple derivation of this is given with the aid of
Wang, Fang; Wang, Lin; Chen, Yuming
2017-08-31
In order to investigate the time-dependent cross-correlations of fine particulate (PM2.5) series among neighboring cities in Northern China, in this paper, we propose a new cross-correlation coefficient, the time-lagged q-L dependent height crosscorrelation coefficient (denoted by p q (τ, L)), which incorporates the time-lag factor and the fluctuation amplitude information into the analogous height cross-correlation analysis coefficient. Numerical tests are performed to illustrate that the newly proposed coefficient ρ q (τ, L) can be used to detect cross-correlations between two series with time lags and to identify different range of fluctuations at which two series possess cross-correlations. Applying the new coefficient to analyze the time-dependent cross-correlations of PM2.5 series between Beijing and the three neighboring cities of Tianjin, Zhangjiakou, and Baoding, we find that time lags between the PM2.5 series with larger fluctuations are longer than those between PM2.5 series withsmaller fluctuations. Our analysis also shows that cross-correlations between the PM2.5 series of two neighboring cities are significant and the time lags between two PM2.5 series of neighboring cities are significantly non-zero. These findings providenew scientific support on the view that air pollution in neighboring cities can affect one another not simultaneously but with a time lag.
Correlation coefficient based supervised locally linear embedding for pulmonary nodule recognition.
Wu, Panpan; Xia, Kewen; Yu, Hengyong
2016-11-01
Dimensionality reduction techniques are developed to suppress the negative effects of high dimensional feature space of lung CT images on classification performance in computer aided detection (CAD) systems for pulmonary nodule detection. An improved supervised locally linear embedding (SLLE) algorithm is proposed based on the concept of correlation coefficient. The Spearman's rank correlation coefficient is introduced to adjust the distance metric in the SLLE algorithm to ensure that more suitable neighborhood points could be identified, and thus to enhance the discriminating power of embedded data. The proposed Spearman's rank correlation coefficient based SLLE (SC(2)SLLE) is implemented and validated in our pilot CAD system using a clinical dataset collected from the publicly available lung image database consortium and image database resource initiative (LICD-IDRI). Particularly, a representative CAD system for solitary pulmonary nodule detection is designed and implemented. After a sequential medical image processing steps, 64 nodules and 140 non-nodules are extracted, and 34 representative features are calculated. The SC(2)SLLE, as well as SLLE and LLE algorithm, are applied to reduce the dimensionality. Several quantitative measurements are also used to evaluate and compare the performances. Using a 5-fold cross-validation methodology, the proposed algorithm achieves 87.65% accuracy, 79.23% sensitivity, 91.43% specificity, and 8.57% false positive rate, on average. Experimental results indicate that the proposed algorithm outperforms the original locally linear embedding and SLLE coupled with the support vector machine (SVM) classifier. Based on the preliminary results from a limited number of nodules in our dataset, this study demonstrates the great potential to improve the performance of a CAD system for nodule detection using the proposed SC(2)SLLE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Robustness of the Distribution Theory of the Product Moment Correlation Coefficient.
Kraemer, Helena Chmura
1980-01-01
The robustness of hypothesis tests for the correlation coefficient under varying conditions is discussed. The effects of violations of the assumptions of linearity, homoscedasticity, and kurtosis are examined. (JKS)
Piretzidis, Dimitrios; Sra, Gurveer; Karantaidis, George; Sideris, Michael G.
2017-04-01
A new method for identifying correlated errors in Gravity Recovery and Climate Experiment (GRACE) monthly harmonic coefficients has been developed and tested. Correlated errors are present in the differences between monthly GRACE solutions, and can be suppressed using a de-correlation filter. In principle, the de-correlation filter should be implemented only on coefficient series with correlated errors to avoid losing useful geophysical information. In previous studies, two main methods of implementing the de-correlation filter have been utilized. In the first one, the de-correlation filter is implemented starting from a specific minimum order until the maximum order of the monthly solution examined. In the second one, the de-correlation filter is implemented only on specific coefficient series, the selection of which is based on statistical testing. The method proposed in the present study exploits the capabilities of supervised machine learning algorithms such as neural networks and support vector machines (SVMs). The pattern of correlated errors can be described by several numerical and geometric features of the harmonic coefficient series. The features of extreme cases of both correlated and uncorrelated coefficients are extracted and used for the training of the machine learning algorithms. The trained machine learning algorithms are later used to identify correlated errors and provide the probability of a coefficient series to be correlated. Regarding SVMs algorithms, an extensive study is performed with various kernel functions in order to find the optimal training model for prediction. The selection of the optimal training model is based on the classification accuracy of the trained SVM algorithm on the same samples used for training. Results show excellent performance of all algorithms with a classification accuracy of 97% - 100% on a pre-selected set of training samples, both in the validation stage of the training procedure and in the subsequent use of
Crowell, Ed; Wang, Gufeng; Cox, Jason; Platz, Charles P; Geng, Lei
2005-03-01
Correlation coefficient mapping has been applied to intrinsic fluorescence spectra of colonic tissue for the purpose of cancer diagnosis. Fluorescence emission spectra were collected of 57 colonic tissue sites in a range of 4 physiological conditions: normal (29), hyperplastic (2), adenomatous (5), and cancerous tissues (21). The sample-sample correlation was used to examine the ability of correlation coefficient mapping to determine tissue disease state. The correlation coefficient map indicates two main categories of samples. These categories were found to relate to disease states of the tissue. Sensitivity, selectivity, predictive value positive, and predictive value negative for differentiation between normal tissue and all other categories were all above 92%. This was found to be similar to, or higher than, tissue classification using existing methods of data reduction. Wavelength-wavelength correlation among the samples highlights areas of importance for tissue classification. The two-dimensional correlation map reveals absorption by NADH and hemoglobin in the samples as negative correlation, an effect not obvious from the one-dimensional fluorescence spectra alone. The integrity of tissue was examined in a time series of spectra of a single tissue sample taken after tissue resection. The wavelength-wavelength correlation coefficient map shows the areas of significance for each fluorophore and their relation to each other. NADH displays negative correlation to collagen and FAD, from the absorption of emission or fluorescence resonance energy transfer. The wavelength-wavelength correlation map for the decay set also clearly shows that there are only three fluorophores of importance in the samples, by the well-defined pattern of the map. The sample-sample correlation coefficient map reveals the changes over time and their impact on tissue classification. Correlation coefficient mapping proves to be an effective method for sample classification and cancer
Observations of copolar correlation coefficient through a bright band at vertical incidence
Zrnic, D. S.; Raghavan, R.; Chandrasekar, V.
1994-01-01
This paper discusses an application of polarimetric measurements at vertical incidence. In particular, the correlation coefficients between linear copolar components are examined, and measurements obtained with the National Severe Storms Laboratory (NSSL)'s and National Center for Atmospheric Research (NCAR)'s polarimetric radars are presented. The data are from two well-defined bright bands. A sharp decrease of the correlation coefficient, confined to a height interval of a few hundred meters, marks the bottom of the bright band.
A Robust Multiple Correlation Coefficient for the Rank Analysis of Linear Models.
1983-09-01
A multiple correlation coefficient is discussed to measure the degree of association between a random variable Y and a set of random variables X sub...approach of analyzing linear models in a regression, prediction context. The population parameter equals the classical multiple correlation ... coefficient if the multivariate normal model holds but would be more robust for departures from this model. Some results are given on the consistency of the sample estimate and on a test for independence. (Author)
Provenzale, James M; Isaacson, Jared; Chen, Steven; Stinnett, Sandra; Liu, Chunlei
2010-12-01
The purpose of our study was to correlate decrease in apparent diffusion coefficient (ADC) and increase in fractional anisotropy (FA) in various white matter (WM) regions using diffusion tenor imaging (DTI) within the first year of life. We performed DTI on 53 infants and measured FA and ADC within 10 WM regions important in brain development. For each region, we calculated the slope of ADC as a function of FA, the correlation coefficient (r) and correlation of determination (r(2)). We performed a group analysis of r values and r(2)values for six WM regions primarily composed of crossing fibers and four regions primarily having parallel fibers. Upon finding that a strong correlation of FA with age existed, we adjusted for age and calculated partial correlation coefficients. Slopes of FA versus ADC ranged from -1.00711 to -1.67592 (p correlation coefficients ranged from -0.49 to 0.03 and r(2) values from 0.31 to 0.79. The highest partial correlation coefficients were then relatively equally distributed between the two types of WM regions. In various regions, FA and ADC evolved with differing degrees of correlation. We found a strong influence of age on the relationship between FA and ADC.
Surov, Alexey; Meyer, Hans Jonas; Wienke, Andreas
2017-07-01
Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique based on measure of water diffusion that can provide information about tissue microstructure, especially about cell count. Increase of cell density induces restriction of water diffusion and decreases apparent diffusion coefficient (ADC). ADC can be divided into three sub-parameters: ADC minimum or ADCmin, mean ADC or ADCmean and ADC maximum or ADCmax Some studies have suggested that ADCmin shows stronger correlations with cell count in comparison to other ADC fractions and may be used as a parameter for estimation of tumor cellularity. The aim of the present meta-analysis was to summarize correlation coefficients between ADCmin and cellularity in different tumors based on large patient data. For this analysis, MEDLINE database was screened for associations between ADC and cell count in different tumors up to September 2016. For this work, only data regarding ADCmin were included. Overall, 12 publications with 317 patients were identified. Spearman's correlation coefficient was used to analyze associations between ADCmin and cellularity. The reported Pearson correlation coefficients in some publications were converted into Spearman correlation coefficients. The pooled correlation coefficient for all included studies was ρ=-0.59 (95% confidence interval (CI)=-0.72 to -0.45), heterogeneity Tau(2)=0.04 (pcorrelated moderately with tumor cellularity. The calculated correlation coefficient is not stronger in comparison to the reported coefficient for ADCmean and, therefore, ADCmin does not represent a better means to reflect cellularity. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.
Du, Hongli; Hu, Haofu; Meng, Yuhuan; Zheng, Weihao; Ling, Fei; Wang, Jufang; Zhang, Xiquan; Nie, Qinghua; Wang, Xiaoning
2010-09-24
In this study, we present a new method for evaluating animal evolutionary relationships. We used the GC% levels of genome-wide genes to determine the correlation between the GC% content and evolutionary relationship. The correlation coefficients of the GC% content of the orthologous genes of the paired animal species were calculated for a total of 21 species, and the evolutionary branching dates of these 21 species were derived from fossil records. The correlation coefficient of the GC% content of the orthologous genes of the species pair under study served as an indicator of their evolutionary relationship. Moreover, there was a decreasing linear relationship between the correlation coefficient and evolutionary branching date (R(2)=0.930).
Shou, H; Eloyan, A; Lee, S; Zipunnikov, V; Crainiceanu, A N; Nebel, N B; Caffo, B; Lindquist, M A; Crainiceanu, C M
2013-12-01
This article proposes the image intraclass correlation (I2C2) coefficient as a global measure of reliability for imaging studies. The I2C2 generalizes the classic intraclass correlation (ICC) coefficient to the case when the data of interest are images, thereby providing a measure that is both intuitive and convenient. Drawing a connection with classical measurement error models for replication experiments, the I2C2 can be computed quickly, even in high-dimensional imaging studies. A nonparametric bootstrap procedure is introduced to quantify the variability of the I2C2 estimator. Furthermore, a Monte Carlo permutation is utilized to test reproducibility versus a zero I2C2, representing complete lack of reproducibility. Methodologies are applied to three replication studies arising from different brain imaging modalities and settings: regional analysis of volumes in normalized space imaging for characterizing brain morphology, seed-voxel brain activation maps based on resting-state functional magnetic resonance imaging (fMRI), and fractional anisotropy in an area surrounding the corpus callosum via diffusion tensor imaging. Notably, resting-state fMRI brain activation maps are found to have low reliability, ranging from .2 to .4. Software and data are available to provide easy access to the proposed methods.
Zhuang, H; Savage, E M
2009-01-01
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 texture can vary from location to location within individual muscles. The objective of our study was to investigate the intramuscular variation and Pearson correlation coefficients of Warner-Bratzler (WB) shear force measurements within early deboned broiler breast fillets and the effect of deboning time and cold storage on the variation and correlation coefficients. Broiler breast fillets were removed from carcasses early postmortem (2 h) and later postmortem (24 h). Storage treatments of the 2 h samples included 0 d, 7 d at 3 degrees C, 7 d at -20 degrees C, and 6 d at -20 degrees C plus 1 d at 3 degrees C. The WB shears of cooked fillets were measured using a TA-XTPlus Texture Analyzer and a TA-7 WB shear type blade. Our results showed that although the average WB shear force values differed within the 0-d, 2-h fillets, compared with the variation among the fillets within the treatment, the difference within a fillet is still evidently small. The Pearson correlation coefficients were significant between the locations; however, values of the correlation coefficients depended on the paired locations. Location differences in the WB shear values and the correlation coefficient values between them changed with deboning time and cold storage. These results demonstrate that the variation of WB shear force measurements is substantial within early deboned broiler breast fillets and the Pearson correlation coefficient values of the measurements vary among the locations. Both the variation and the Pearson correlation coefficients can be affected by postmortem aging time and storage. The differences in the means between the locations in early deboned breasts are much smaller than the
Correlation of apparent diffusion coefficient with Ki-67 proliferation index in grading meningioma.
Tang, Yi; Dundamadappa, Sathish K; Thangasamy, Senthur; Flood, Thomas; Moser, Richard; Smith, Thomas; Cauley, Keith; Takhtani, Deepak
2014-06-01
A noninvasive method to predict aggressiveness of high-grade meningiomas would be desirable because it would help anticipate tumor recurrence and improve tumor management and the treatment outcomes. The Ki-67 protein is a marker of tumor proliferation, and apparent diffusion coefficient (ADC) is related to tumor cellularity. Therefore, we sought to determine whether there is a statistically significant correlation between ADC and Ki-67 values in meningiomas and whether ADC values can differentiate various meningioma subtypes. MRI examinations and histopathology of 68 surgically treated meningiomas were retrospectively reviewed. Mean ADC values were derived from diffusion imaging. Correlation coefficients were calculated for mean ADC and Ki-67 proliferation index values using linear regression. An independent unpaired Student t test was used to compare the ADC and Ki-67 proliferation index values from low-grade and more aggressive meningiomas. A statistically significant inverse correlation was found between ADC and Ki-67 proliferation index for low-grade and aggressive meningiomas (r(2) = -0.33, p = 0.0039). ADC values (± SD) of low-grade meningiomas (0.84 ± 0.14 × 10(-3) mm(2)/s) and aggressive (atypical or anaplastic) meningiomas (0.75 ± 0.03 × 10(-3) mm(2)/s) were significantly different (p = 0.0495). Using an ADC cutoff value of 0.70 × 10(-3) mm(2)/s, the sensitivity for diagnosing aggressive meningiomas was 29%, specificity was 94%, positive predictive value was 67%, and negative predictive value was 75%. ADC values correlate inversely with Ki-67 proliferation index and help differentiate low-grade from aggressive meningiomas.
Energy Technology Data Exchange (ETDEWEB)
Cipolla, Valentina, E-mail: valentina.cipolla@yahoo.it [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Santucci, Domiziana; Guerrieri, Daniele; Drudi, Francesco Maria [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Meggiorini, Maria Letizia [Department of Gynaecological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy); Felice, Carlo de [Department of Radiological Sciences, University of Rome “Sapienza”, Viale del Policlinico 155, 00161 Rome (Italy)
2014-12-15
Highlights: • Apparent diffusion coefficient is a quantitative parameter which reflects molecular water movement. • Grading is an independent prognostic factor which correlates with other histopathological features. • Apparent diffusion coefficient values were significantly different between G1 and G3 classes. - Abstract: Purpose: The aim of this study was to evaluate whether the apparent diffusion coefficient (ADC) provided by 3.0 T (3 T) magnetic resonance diffusion-weighted imaging (DWI) varied according to the grading of invasive breast carcinoma. Materials and methods: A total of 92 patients with 96 invasive breast cancer lesions were enrolled; all had undergone 3 T magnetic resonance imaging (MRI) for local staging. All lesions were confirmed by histological analysis, and tumor grade was established according to the Nottingham Grading System (NGS). MRI included both dynamic contrast-enhanced and DWI sequences, and ADC value was calculated for each lesion. ADC values were compared with NGS classification using the Mann–Whitney U and the Kruskal–Wallis H tests. Grading was considered as a comprehensive prognostic factor, and Rho Spearman test was performed to determine correlation between grading and tumor size, hormonal receptor status, HER2 expression and Ki67 index. Pearson's Chi square test was carried out to compare grading with the other prognostic factors. Results: ADC values were significantly higher in G1 than in G3 tumors. No significant difference was observed when G1 and G3 were compared with G2. Tumor size, hormonal receptor status, HER2 expression and Ki67 index correlated significantly with grading but there was a significant difference only between G1 and G3 related to the ER and PR status, HER2 expression and Ki67 index. There was no statistically significant difference in lesion size between the two groups. Conclusion: ADC values obtained on 3 T DWI correlated with low-grade (G1) and high-grade (G3) invasive breast carcinoma. 3
Khenouchi, H.; Smara, Y.; Migliaccio, M.; Nunziata, F.; Buono, A.
2016-08-01
Sea oil pollution is a matter of great concern since it affects both the environment and human health. Recent studies demonstrated that synthetic aperture radar (SAR) polarimetry is able to provide additional information useful for environmental applications, i. e., oil spill observation. In this context, different approaches based on polarimetric SARs were developed. In this study, a dual-polarimetric feature, namely the modulus of the complex correlation coefficient between the co-polarized channels, is used to discriminate between sea oil spill and weak-damping look-alikes.The proposed approach relies on the fact that high correlation between co-polarized channels is expected over sea surface and weak-damping look- alikes due to the dominant Bragg scattering, while significantly lower correlation is expected over strong-damping oil spills since they are characterized by a no-Bragg scattering behaviour. Experimental results show that the modulus of the complex correlation between the co-polarized chan- nels can be successfully exploited for both the observation of sea oil slicks and their discrimination from weak-damping look-alikes.
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρDXA, contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr.
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρ D X A , contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr.
Cohen, S. C.
1980-01-01
A technique for fitting a straight line to a collection of data points is given. The relationships between the slopes and correlation coefficients, and between the corresponding standard deviations and correlation coefficient are given.
Reducing Bias and Error in the Correlation Coefficient Due to Nonnormality
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…
Reducing Bias and Error in the Correlation Coefficient Due to Nonnormality
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…
An empirical correlation of volumetric mass transfer coefficient was developed for a pilot scale internal-loop rectangular airlift bioreactor that was designed for biotechnology. The empirical correlation combines classic turbulence theory, Kolmogorov’s isotropic turbulence theory with Higbie’s pen...
Peters, Elisabeth; Stuke, Maik
2016-01-01
In this manuscript we study the modeling of experimental data and its impact on the resulting integral experimental covariance and correlation matrices. By investigating a set of three low enriched and water moderated UO2 fuel rod arrays we found that modeling the same set of data with different, yet reasonable assumptions concerning the fuel rod composition and its geometric properties leads to significantly different covariance matrices or correlation coefficients. Following a Monte Carlo sampling approach, we show for nine different modeling assumptions the corresponding correlation coefficients and sensitivity profiles for each pair of the effective neutron multiplication factor keff. Within the 95% confidence interval the correlation coefficients vary from 0 to 1, depending on the modeling assumptions. Our findings show that the choice of modeling can have a huge impact on integral experimental covariance matrices. When the latter are used in a validation procedure to derive a bias, this procedure can be...
Kishimoto, Keiko; Tajima, Shinya; Maeda, Ichiro; Takagi, Masayuki; Ueno, Takahiko; Suzuki, Nao; Nakajima, Yasuo
2016-08-01
Diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) are widely used for detecting uterine endometrial cancer. The relationships between ADC values and pathological features of endometrial cancer have not yet been established. To investigate whether ADC values of endometrial cancer vary according to histologic tumor cellularity and tumor grade. We retrospectively reviewed 30 pathologically confirmed endometrial cancers. All patients underwent conventional non-enhanced magnetic resonance imaging (MRI) and DWI procedures, and ADC values were calculated. Tumor cellularity was evaluated by counting cancer cells in three high-power ( × 400) fields. The correlation between ADC values and tumor cellularity was assessed using Pearson's correlation coefficient test for statistical analysis. The mean ± standard deviation (SD) ADC value ( ×10(-3) mm(2)/s) of endometrial cancer was 0.85 ± 0.22 (range, 0.55-1.71). The mean ± SD tumor cellularity was 528.36 ± 16.89 (range, 298.0-763.6). ADC values were significantly inversely correlated with tumor cellularity. No significant relationship was observed between ADC values and tumor grade (mean ADC values: G1, 0.88 ± 0.265 × 10(-3) mm(2)/s; G2, 0.80 ± 0.178 × 10(-3) mm(2)/s; G3, 0.81 ± 0.117 × 10(-3) mm(2)/s). There is a significant inverse relationship between ADC values and tumor cellularity in endometrial cancer. No significant differences in average ADC value were observed between G1, G2, and G3 tumors. However, the lower the tumor grade, the wider the SD. © The Foundation Acta Radiologica 2015.
Wheeler, David; Tiefelsdorf, Michael
2005-06-01
Present methodological research on geographically weighted regression (GWR) focuses primarily on extensions of the basic GWR model, while ignoring well-established diagnostics tests commonly used in standard global regression analysis. This paper investigates multicollinearity issues surrounding the local GWR coefficients at a single location and the overall correlation between GWR coefficients associated with two different exogenous variables. Results indicate that the local regression coefficients are potentially collinear even if the underlying exogenous variables in the data generating process are uncorrelated. Based on these findings, applied GWR research should practice caution in substantively interpreting the spatial patterns of local GWR coefficients. An empirical disease-mapping example is used to motivate the GWR multicollinearity problem. Controlled experiments are performed to systematically explore coefficient dependency issues in GWR. These experiments specify global models that use eigenvectors from a spatial link matrix as exogenous variables.
Directory of Open Access Journals (Sweden)
Shumanova M.V.
2015-03-01
Full Text Available The process fish salting has been studied by the method of photon correlation spectroscopy; the distribution of salt concentration in the solution and herring flesh with skin has been found, diffusion coefficients and salt concentrations used for creating a mathematical model of the salting technology have been worked out; the possibility of determination by this method the coefficient of dynamic viscosity of solutions and different media (minced meat etc. has been considered
DEFF Research Database (Denmark)
Boesen, Lars; Chabanova, Elizaveta; Løgager, Vibeke
2015-01-01
PURPOSE: To evaluate the correlation between apparent diffusion coefficient measurements (ADCtumor and ADCratio ) and the Gleason score from radical prostatectomy specimens. MATERIALS AND METHODS: Seventy-one patients with clinically localized prostate cancer scheduled for radical prostatectomy...... correlated with the Gleason score from the prostatectomy specimens. RESULTS: The association between ADC measurements and Gleason score showed a significant negative correlation (P ... ) and 0.90 (ADCratio ) when discriminating Gleason score ≤7(3+4) from Gleason score ≥7(4+3). CONCLUSION: ADC measurements showed a significant correlation with tumor Gleason score at final pathology. The ADCratio demonstrated the best correlation compared to the ADCtumor value and radically improved...
Zhao, Qile; Guo, Jing; Hu, Zhigang; Shi, Chuang; Liu, Jingnan; Cai, Hua; Liu, Xianglin
2011-05-01
The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%-30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is
Kim, Mimi; Kang, Tae Wook; Kim, Young Kon; Kim, Seong Hyun; Kwon, Wooil; Ha, Sang Yun; Ji, Sang A
2016-03-01
To evaluate the correlation between grade of pancreatic neuroendocrine tumours (pNETs) based on the 2010 World Health Organization (WHO) classification and the apparent diffusion coefficient (ADC), and to assess whether the ADC value and WHO classification can predict recurrence-free survival (RFS) after surgery for pNETs. This retrospective study was approved by the Institutional Review Board. The requirement for informed consent was waived. Between March 2009 and November 2014, forty-nine patients who underwent magnetic resonance (MR) imaging with diffusion-weighted image and subsequent surgery for single pNETs were included. Correlations among qualitative MR imaging findings, quantitative ADC values, and WHO classifications were assessed. An ordered logistic regression test was used to control for tumour size as a confounding factor. The association between ADC value (or WHO classification) and RFS was analysed. All tumors (n=49) were classified as low- (n=29, grade 1), intermediate- (n=17, grade 2), and high-grade (n=3, grade 3), respectively. The mean ADC of pNETs was moderately negatively correlated with WHO classification before and after adjustment for tumour size (ρ=-0.64, pcorrelated with WHO tumour grade, regardless of tumour size. However, the WHO tumour classification of pNET may be more suitable for predicting RFS than the ADC value. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Tao, Kai; Grand, Stephen P.; Niu, Fenglin
2017-09-01
In seismic full-waveform inversion (FWI), the choice of misfit function determines what information in data is used and ultimately affects the resolution of the inverted images of the Earth's structure. Misfit functions based on traveltime have been successfully applied in global and regional tomographic studies. However, wave propagation through the upper mantle results in multiple phases arriving at a given receiver in a narrow time interval resulting in complicated waveforms that evolve with distance. To extract waveform information as well as traveltime, we use a misfit function based on the normalized correlation coefficient (CC). This misfit function is able to capture the waveform complexities in both phase and relative amplitude within the measurement window. It is also insensitive to absolute amplitude differences between modeled and recorded data, which avoids problems due to uncertainties in source magnitude, radiation pattern, receiver site effects or even miscalibrated instruments. These features make the misfit function based on normalized CC a good candidate to achieve high-resolution images of complex geological structures when interfering phases coexist in the measurement window, such as triplication waveforms. From synthetic tests, we show the advantages of this misfit function over the cross-correlation traveltime misfit function. Preliminary inversion of data from an earthquake in Northeast China images a sharper and stronger amplitude slab stagnant in the middle of the transition zone than FWI of cross-correlation traveltime.
Quantized correlation coefficient for measuring reproducibility of ChIP-chip data.
Peng, Shouyong; Kuroda, Mitzi I; Park, Peter J
2010-07-27
Chromatin immunoprecipitation followed by microarray hybridization (ChIP-chip) is used to study protein-DNA interactions and histone modifications on a genome-scale. To ensure data quality, these experiments are usually performed in replicates, and a correlation coefficient between replicates is used often to assess reproducibility. However, the correlation coefficient can be misleading because it is affected not only by the reproducibility of the signal but also by the amount of binding signal present in the data. We develop the Quantized correlation coefficient (QCC) that is much less dependent on the amount of signal. This involves discretization of data into set of quantiles (quantization), a merging procedure to group the background probes, and recalculation of the Pearson correlation coefficient. This procedure reduces the influence of the background noise on the statistic, which then properly focuses more on the reproducibility of the signal. The performance of this procedure is tested in both simulated and real ChIP-chip data. For replicates with different levels of enrichment over background and coverage, we find that QCC reflects reproducibility more accurately and is more robust than the standard Pearson or Spearman correlation coefficients. The quantization and the merging procedure can also suggest a proper quantile threshold for separating signal from background for further analysis. To measure reproducibility of ChIP-chip data correctly, a correlation coefficient that is robust to the amount of signal present should be used. QCC is one such measure. The QCC statistic can also be applied in a variety of other contexts for measuring reproducibility, including analysis of array CGH data for DNA copy number and gene expression data.
Energy Technology Data Exchange (ETDEWEB)
Trier, A.; Cabrini, N.; Ferrer, J. [Facultad de Ciencia, Universidad de Santiago de Chile, Santiago 2 (Chile); Olaeta, I. [SESMA, Santiago 1 (Chile)
1997-07-01
Total horizontal atmospheric light extinction coefficients as well as particle mass concentrations have been measured in downtown areas of Santiago de Chile, a heavily polluted city. Measurement campaigns were carried out in 1994 in 1995. Extinction measurements were made by a telephotometric technique in four wavelength bands; oscillating mass balance type instruments were used to measure PM2.5 and PM10 mass concentrations. The latter type instrument had not been available heretofore. The extensive continuous PM2.5 measurements are the first for this city. Strong and highly significant statistical correlations were found between extinction coefficients and mass concentrations, especially with the fine respirable or PM2.5 mass concentrations. Angstrom exponents and, in one case, mass extinction coefficients have been estimated. [Spanish] Se ha medido coeficientes atmosfericos totales horizontales de extincion de luz asi como concentraciones de masa de particulas atmosfericas en zonas centricas de Santiago de Chile, una ciudad altamente contaminada. Las campanas de medicion se han hecho en 1994 y en 1995. Las mediciones de extincion se han hecho por un metodo telefotometrico en cuatro bandas espectrales; las concentraciones de masa PM2.5 y PM10 se han medido con instrumentos del tipo de balanzas de masa oscilantes. Tales instrumentos no han estado disponibles durante trabajos anteriores. Las extensas mediciones continuas de concentraciones de masa PM2.5 son las primeras para Santiago de Chile. Se han encontrado fuertes correlaciones estadisticas, altamente significativas, entre coeficientes de extincion y concentraciones de masa, especialmente las concentraciones de particulas finas respirables PM2.5. Se han estimado tambien exponentes de Angstrom y, en un caso, coeficientes masicos de extincion.
DEFF Research Database (Denmark)
Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw
2014-01-01
Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable...... to the correlation function yields the diffusion coefficient. This paper provides a step-by-step guide to the image analysis and measurement of diffusion coefficients via kICS. First, a high frame rate image sequence of a fluorescently labeled plasma membrane protein is acquired using a fluorescence microscope Then...... routine measurements of diffusion coefficients directly from images of fluorescently tagged plasma membrane proteins, that avoided systematic biases introduced by probe photophysics. Although the theoretical basis for the analysis is complex, the method can be implemented by nonexperts using a freely...
Yue, Chen; Chen, Shaojie; Sair, Haris I; Airan, Raag; Caffo, Brian S
2015-09-01
Data reproducibility is a critical issue in all scientific experiments. In this manuscript, the problem of quantifying the reproducibility of graphical measurements is considered. The image intra-class correlation coefficient (I2C2) is generalized and the graphical intra-class correlation coefficient (GICC) is proposed for such purpose. The concept for GICC is based on multivariate probit-linear mixed effect models. A Markov Chain Monte Carlo EM (mcm-cEM) algorithm is used for estimating the GICC. Simulation results with varied settings are demonstrated and our method is applied to the KIRBY21 test-retest dataset.
Choosing the best index for the average score intraclass correlation coefficient.
Shieh, Gwowen
2016-09-01
The intraclass correlation coefficient (ICC)(2) index from a one-way random effects model is widely used to describe the reliability of mean ratings in behavioral, educational, and psychological research. Despite its apparent utility, the essential property of ICC(2) as a point estimator of the average score intraclass correlation coefficient is seldom mentioned. This article considers several potential measures and compares their performance with ICC(2). Analytical derivations and numerical examinations are presented to assess the bias and mean square error of the alternative estimators. The results suggest that more advantageous indices can be recommended over ICC(2) for their theoretical implication and computational ease.
Study of cross correlation coefficients of temperature fluctuations in a longitudinal magnetic field
Energy Technology Data Exchange (ETDEWEB)
Genin, L.G.; Manchkha, S.P.; Sviridov, V.G.
1977-01-01
An experimental study was made of the effect that a longitudinal magnetic field has on correlation coefficients of temperature fluctuations in a transverse direction. This effect on those fluctuations was shown to be small in comparison to its effect on the coefficients of longitudinal correlation. This indicates that the structure of the temperature field becomes more anisotropic so that there is an increase in the scale of turbulent disturbances in the direction of the magnetic field's force lines. 1 figure, 2 references.
Aoki, T; Watanabe, A; Nitta, N; Numano, T; Fukushi, M; Niitsu, M
2012-09-01
Quantitative MR imaging techniques of degenerative cartilage have been reported as useful indicators of degenerative changes in cartilage extracellular matrix, which consists of proteoglycans, collagen, non-collagenous proteins, and water. Apparent diffusion coefficient (ADC) mapping of cartilage has been shown to correlate mainly with the water content of the cartilage. As the water content of the cartilage in turn correlates with its viscoelasticity, which directly affects the mechanical strength of articular cartilage, ADC can serve as a potentially useful indicator of the mechanical strength of cartilage. The aim of this study was to investigate the correlation between ADC and viscoelasticity as measured by indentation testing. Fresh porcine knee joints (n = 20, age 6 months) were obtained from a local abattoir. ADC of porcine knee cartilage was measured using a 3-Tesla MRI. Indentation testing was performed on an electromechanical precision-controlled system, and viscosity coefficient and relaxation time were measured as additional indicators of the viscoelasticity of cartilage. The relationship between ADC and viscosity coefficient as well as that between ADC and relaxation time were assessed. ADC was correlated with relaxation time and viscosity coefficient (R(2) = 0.75 and 0.69, respectively, p correlation between ADC and viscoelasticity in the superficial articular cartilage. Both molecular diffusion and viscoelasticity were higher in weight bearing than non-weight-bearing articular cartilage areas.
On the solar cycle variation in the barometer coefficients of high latitude neutron monitors
Kusunose, M.; Ogita, N.
1985-01-01
Evaluation of barometer coefficients of neutron monitors located at high latitudes has been performed by using the results of the spherical harmonic analysis based on the records from around twenty stations for twelve years from January 1966 to December 1977. The average of data at eight stations, where continuous records are available for twelve years, show that the absolute value of barometer coefficient is in positive correlation with the cosmic ray neutron intensity. The variation rate of the barometer coefficient to the cosmic ray neutron intensity is influenced by the changes in the cutoff rigidity and in the primary spectrum.
Dynamic coefficients of axial spline couplings in high-speed rotating machinery
Energy Technology Data Exchange (ETDEWEB)
Ku, C.P.R.; Walton, J.F. Jr. (Mechanical Technology Inc., Latham, NY (United States)); Lund, J.W. (Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Machine Elements)
1994-07-01
This paper provided the first opportunity to quantify the angular stiffness and equivalent viscous damping coefficients of an axial spline coupling used in high-speed turbomachinery. The bending moments and angular deflections transmitted across an axial spline coupling were measured while a nonrotating shaft was excited by an external shaker. A rotordynamics computer program was used to simulate the test conditions and to correlate the angular stiffness and damping coefficients. The effects of external force and frequency were also investigated. The angular stiffness and damping coefficients were used to perform a linear steady-state rotordynamics stability analysis, and the unstable natural frequency was calculated and compared to the experimental measurements.
Institute of Scientific and Technical Information of China (English)
Liu Yanqiong; Chen Yingwu
2006-01-01
When analyze the uncertainty of the cost and the schedule of the spaceflight project, it is needed to know the value of the schedule-cost correlation coefficient. This paper deduces the schedule distribution, considering the effect of the cost, and proposes the estimation formula of the correlation coefficient between the ln(schedule) and the cost. On the basis of the fact and Taylor expansion, the relation expression between the schedule-cost correlation coefficient and the ln-schedule-cost correlation coefficient is put forward. By analyzing the value features of the estimation formula of the ln-schedule-cost correlation coefficient, the general rules are proposed to ascertain the value of the schedule-cost correlation coefficient. An example is given to demonstrate how to approximately amend the schedule-cost correlation coefficient based on the historical statistics, which reveals the traditional assigned value is inaccurate. The universality of this estimation method is analyzed.
High-Order Dispersion Coefficients for Alkali-metal Atoms
Institute of Scientific and Technical Information of China (English)
KANG Shuai; DING Chi-Kun; CHEN Chang-Yong; WU Xue-Qing
2013-01-01
High-order dispersion coefficients C9,C11,C12,and C13 for the ground-state alkali-metals were calculated by combining the l-dependent model potential of alkali-metal atoms and linear variation method based on B-spline basis functions.The results were compared.
Barlow, Andrew L; Macleod, Alasdair; Noppen, Samuel; Sanderson, Jeremy; Guérin, Christopher J
2010-12-01
One of the most routine uses of fluorescence microscopy is colocalization, i.e., the demonstration of a relationship between pairs of biological molecules. Frequently this is presented simplistically by the use of overlays of red and green images, with areas of yellow indicating colocalization of the molecules. Colocalization data are rarely quantified and can be misleading. Our results from both synthetic and biological datasets demonstrate that the generation of Pearson's correlation coefficient between pairs of images can overestimate positive correlation and fail to demonstrate negative correlation. We have demonstrated that the calculation of a thresholded Pearson's correlation coefficient using only intensity values over a determined threshold in both channels produces numerical values that more accurately describe both synthetic datasets and biological examples. Its use will bring clarity and accuracy to colocalization studies using fluorescent microscopy.
VARYING COEFFICIENT MODELS FOR DATA WITH AUTO-CORRELATED ERROR PROCESS.
Chen, Zhao; Li, Runze; Li, Yan
2015-04-01
Varying coefficient model has been popular in the literature. In this paper, we propose a profile least squares estimation procedure to its regression coefficients when its random error is an auto-regressive (AR) process. We further study the asymptotic properties of the proposed procedure, and establish the asymptotic normality for the resulting estimate. We show that the resulting estimate for the regression coefficients has the same asymptotic bias and variance as the local linear estimate for varying coefficient models with independent and identically distributed observations. We apply the SCAD variable selection procedure (Fan and Li, 2001) to reduce model complexity of the AR error process. Numerical comparison and finite sample performance of the resulting estimate are examined by Monte Carlo studies. Our simulation results demonstrate the proposed procedure is much more efficient than the one ignoring the error correlation. The proposed methodology is illustrated by a real data example.
Booi, Rebecca C; Carson, Paul L; O'Donnell, Matthew; Roubidoux, Marilyn A; Hall, Anne L; Rubin, Jonathan M
2008-01-01
Although simple cysts are easily identified using sonography, description and management of nonsimple cysts remains uncertain. This study evaluated whether the correlation coefficient differences between breast tissue and lesions, obtained from 2D breast elastography, could potentially distinguish nonsimple cysts from cancers and fibroadenomas. We hypothesized that correlation coefficients in cysts would be dramatically lower than surrounding tissue because noise, imaging artifacts, and particulate matter move randomly and decorrelate quickly under compression, compared with solid tissue. For this preliminary study, 18 breast lesions (7 nonsimple cysts, 4 cancers, and 7 fibroadenomas) underwent imaging with 2D elastography at 7.5 MHz through a TPX (a polymethyl pentene copolymer) 2.5 mm mammographic paddle. Breasts were compressed similar to mammographic positioning and then further compressed for elastography by 1 to 7%. Images were correlated using 2D phase-sensitive speckle tracking algorithms and displacement estimates were accumulated. Correlation coefficient means and standard deviations were measured in the lesion and adjacent tissue, and the differential correlation coefficient (DCC) was introduced as the difference between these values normalized to the correlation coefficient of adjacent tissue. Mean DCC values in nonsimple cysts were 24.2 +/- 11.6%, 5.7 +/- 6.3% for fibroadenomas, and 3.8 +/- 2.9 % for cancers (p < 0.05). Some of the cysts appeared smaller in DCC images than gray-scale images. These encouraging results demonstrate that characterization of nonsimple breast cysts may be improved by using DCC values from 2D elastography, which could potentially change management options of these cysts from intervention to imaging follow-up. A dedicated clinical trial to fully assess the efficacy of this technique is recommended.
Institute of Scientific and Technical Information of China (English)
Xuemei HU; Feng LIU; Zhizhong WANG
2009-01-01
The authors propose a V_(N,P) test statistic for testing finite-order serial correlation in a semiparametric varying coefficient partially linear errors-in-variables model. The test statistic is shown to have asymptotic normal distribution under the null hypothesis of no serial correlation. Some Monte Carlo experiments are conducted to examine the finite sample performance of the proposed V_(N,P) test statistic. Simulation results confirm that the proposed test performs satisfactorily in estimated size and power.
Estimation of high temperature metal-silicate partition coefficients
Jones, John H.; Capobianco, Christopher J.; Drake, Michael J.
1992-01-01
It has been known for some time that abundances of siderophile elements in the upper mantle of the Earth are far in excess of those expected from equilibrium between metal and silicate at low pressures and temperatures. Murthy (1991) has re-examined this excess of siderophile element problem by estimating liquid metal/liquid silicate partition coefficients reduces from their measured values at a lower temperature, implying that siderophile elements become much less siderophilic at high temperatures. Murthy then draws the important conclusion that metal/silicate equilibrium at high temperatures can account for the abundances of siderophile elements in the Earth's mantle. Of course, his conclusion is critically dependent on the small values of the partition coefficients he calculates. Because the numerical values of most experimentally-determined partition coefficients increase with increasing temperature at both constant oxygen fugacity and at constant redox buffer, we think it is important to try an alternative extrapolation for comparison. We have computed high temperature metal/silicate partition coefficients under a different set of assumptions and show that such long temperature extrapolations yield values which are critically dependent upon the presumed chemical behavior of the siderophile elements in the system.
Taler, Dawid
2012-09-01
This paper presents a numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined using a nonlinear regression method. Correlation coefficients were determined from the condition that the sum of squared liquid and air temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The uncertainty in estimated parameters was determined using the error propagation rule by Gauss. The outlet temperature of the liquid and air leaving the heat exchanger was calculated using the analytical model of the heat exchanger.
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
Egghe, L.; Leydesdorff, L.
2009-01-01
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points,
Sample Size Calculation for Estimating or Testing a Nonzero Squared Multiple Correlation Coefficient
Krishnamoorthy, K.; Xia, Yanping
2008-01-01
The problems of hypothesis testing and interval estimation of the squared multiple correlation coefficient of a multivariate normal distribution are considered. It is shown that available one-sided tests are uniformly most powerful, and the one-sided confidence intervals are uniformly most accurate. An exact method of calculating sample size to…
LARGE DEVIATION FOR THE EMPIRICAL CORRELATION COEFFICIENT OF TWO GAUSSIAN RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
Shen Si
2007-01-01
In this article, the author obtains the large deviation principles for the empirical correlation coefficient of two Gaussian random variables X and Y. Especially, when considering two independent Gaussian random variables X, Y with the means EX, EY(both known), wherein the author gives two kinds of different proofs and gets the same results.
Sample Size Calculation for Estimating or Testing a Nonzero Squared Multiple Correlation Coefficient
Krishnamoorthy, K.; Xia, Yanping
2008-01-01
The problems of hypothesis testing and interval estimation of the squared multiple correlation coefficient of a multivariate normal distribution are considered. It is shown that available one-sided tests are uniformly most powerful, and the one-sided confidence intervals are uniformly most accurate. An exact method of calculating sample size to…
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
Egghe, L.; Leydesdorff, L.
2009-01-01
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points,
Raykov, Tenko
2011-01-01
Interval estimation of intraclass correlation coefficients in hierarchical designs is discussed within a latent variable modeling framework. A method accomplishing this aim is outlined, which is applicable in two-level studies where participants (or generally lower-order units) are clustered within higher-order units. The procedure can also be…
Demetrashvili, Nino; Van den Heuvel, Edwin R.
This work is motivated by a meta-analysis case study on antipsychotic medications. The Michaelis-Menten curve is employed to model the nonlinear relationship between the dose and D2 receptor occupancy across multiple studies. An intraclass correlation coefficient (ICC) is used to quantify the
Directory of Open Access Journals (Sweden)
Serge B. Provost
2015-07-01
Full Text Available This paper provides a simplified representation of the exact density function of R, the sample correlation coefficient. The odd and even moments of R are also obtained in closed forms. Being expressed in terms of generalized hypergeometric functions, the resulting representations are readily computable. Some numerical examples corroborate the validity of the results derived herein.
A Novel Approach for Nonstationary Time Series Analysis with Time-Invariant Correlation Coefficient
Directory of Open Access Journals (Sweden)
Chengrui Liu
2014-01-01
Full Text Available We will concentrate on the modeling and analysis of a class of nonstationary time series, called correlation coefficient stationary series, which commonly exists in practical engineering. First, the concept and scope of correlation coefficient stationary series are discussed to get a better understanding. Second, a theorem is proposed to determine standard deviation function for correlation coefficient stationary series. Third, we propose a moving multiple-point average method to determine the function forms for mean and standard deviation, which can help to improve the analysis precision, especially in the context of limited sample size. Fourth, the conditional likelihood approach is utilized to estimate the model parameters. In addition, we discuss the correlation coefficient stationarity test method, which can contribute to the verification of modeling validity. Monte Carlo simulation study illustrates the authentication of the theorem and the validity of the established method. Empirical study shows that the approach can satisfactorily explain the nonstationary behavior of many practical data sets, including stock returns, maximum power load, China money supply, and foreign currency exchange rate. The effectiveness of these processes is addressed by forecasting performance.
Demetrashvili, Nino; Van den Heuvel, Edwin R.
2015-01-01
This work is motivated by a meta-analysis case study on antipsychotic medications. The Michaelis-Menten curve is employed to model the nonlinear relationship between the dose and D2 receptor occupancy across multiple studies. An intraclass correlation coefficient (ICC) is used to quantify the hetero
Cipolla, Valentina; Santucci, Domiziana; Guerrieri, Daniele; Drudi, Francesco Maria; Meggiorini, Maria Letizia; de Felice, Carlo
2014-12-01
The aim of this study was to evaluate whether the apparent diffusion coefficient (ADC) provided by 3.0T (3T) magnetic resonance diffusion-weighted imaging (DWI) varied according to the grading of invasive breast carcinoma. A total of 92 patients with 96 invasive breast cancer lesions were enrolled; all had undergone 3T magnetic resonance imaging (MRI) for local staging. All lesions were confirmed by histological analysis, and tumor grade was established according to the Nottingham Grading System (NGS). MRI included both dynamic contrast-enhanced and DWI sequences, and ADC value was calculated for each lesion. ADC values were compared with NGS classification using the Mann-Whitney U and the Kruskal-Wallis H tests. Grading was considered as a comprehensive prognostic factor, and Rho Spearman test was performed to determine correlation between grading and tumor size, hormonal receptor status, HER2 expression and Ki67 index. Pearson's Chi square test was carried out to compare grading with the other prognostic factors. ADC values were significantly higher in G1 than in G3 tumors. No significant difference was observed when G1 and G3 were compared with G2. Tumor size, hormonal receptor status, HER2 expression and Ki67 index correlated significantly with grading but there was a significant difference only between G1 and G3 related to the ER and PR status, HER2 expression and Ki67 index. There was no statistically significant difference in lesion size between the two groups. ADC values obtained on 3T DWI correlated with low-grade (G1) and high-grade (G3) invasive breast carcinoma. 3T ADC may be a helpful tool for identifying high-grade invasive breast carcinoma. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Reliability sensitivity-based correlation coefficient calculation in structural reliability analysis
Yang, Zhou; Zhang, Yimin; Zhang, Xufang; Huang, Xianzhen
2012-05-01
The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored, which cannot actually reflect the effects of parameter uncertainties on reliability. To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view, the theory principle of the problem is established based on the results of the reliability sensitivity, and the criterion of correlation among random variables is shown. The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed. Numerical studies have shown the following results: (1) If the sensitivity value of correlation coefficient ρ is less than (at what magnitude 0.000 01), then the correlation could be ignored, which could simplify the procedure without introducing additional error. (2) However, as the difference between ρ s, that is the most sensitive to the reliability, and ρ R , that is with the smallest reliability, is less than 0.001, ρ s is suggested to model the dependency of random variables. This could ensure the robust quality of system without the loss of safety requirement. (3) In the case of | E abs|>0.001 and also | E rel|>0.001, ρ R should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis. Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.
Measuring fMRI reliability with the intra-class correlation coefficient.
Caceres, Alejandro; Hall, Deanna L; Zelaya, Fernando O; Williams, Steven C R; Mehta, Mitul A
2009-04-15
The intra-class class correlation coefficient (ICC) is a prominent statistic to measure test-retest reliability of fMRI data. It can be used to address the question of whether regions of high group activation in a first scan session will show preserved subject differentiability in a second session. With this purpose, we present a method that extends voxel-wise ICC analysis. We show that voxels with high group activation have more probability of being reliable, if a subsequent session is performed, than typical voxels across the brain or across white matter. We also find that the existence of some voxels with high ICC but low group activation can be explained by stable signals across sessions that poorly fit the HRF model. At a region of interest level, we show that our voxel-wise ICC calculation is more robust than previous implementations under variations of smoothing and cluster size. The method also allows formal comparisons between the reliabilities of given brain regions; aimed at establishing which ROIs discriminate best between individuals. The method is applied to an auditory and a verbal working memory task. A reliability toolbox for SPM5 is provided at http://brainmap.co.uk.
Influence of self-affine roughness on the friction coefficient of rubber at high sliding velocity
Palasantzas, G
2004-01-01
In this work we investigate the influence of self-affine roughness on the friction coefficient of a rubber body onto a solid surface at high speeds. The roughness is characterized by the rms amplitude w, the correlation length xi, and the roughness exponent H. It is shown that the friction
Gender and Age Analyses of NIRS/STAI Pearson Correlation Coefficients at Resting State.
Matsumoto, T; Fuchita, Y; Ichikawa, K; Fukuda, Y; Takemura, N; Sakatani, K
2016-01-01
According to the valence asymmetry hypothesis, the left/right asymmetry of PFC activity is correlated with specific emotional responses to mental stress and personality traits. In a previous study we measured spontaneous oscillation of oxy-Hb concentrations in the bilateral PFC at rest in normal adults employing two-channel portable NIRS and computed the laterality index at rest (LIR). We investigated the Pearson correlation coefficient between the LIR and anxiety levels evaluated by the State-Trait Anxiety Inventory (STAI) test. We found that subjects with right-dominant activity at rest showed higher STAI scores, while those with left dominant oxy-Hb changes at rest showed lower STAI scores such that the Pearson correlation coefficient between LIR and STAI was positive. This study performed Bootstrap analysis on the data and showed the following statistics of the target correlation coefficient: mean=0.4925 and lower confidence limit=0.177 with confidence level 0.05. Using the KS-test, we demonstrated that the correlation did not depend on age, whereas it did depend on gender.
Evaluation of icing drag coefficient correlations applied to iced propeller performance prediction
Miller, Thomas L.; Shaw, R. J.; Korkan, K. D.
1987-01-01
Evaluation of three empirical icing drag coefficient correlations is accomplished through application to a set of propeller icing data. The various correlations represent the best means currently available for relating drag rise to various flight and atmospheric conditions for both fixed-wing and rotating airfoils, and the work presented here ilustrates and evaluates one such application of the latter case. The origins of each of the correlations are discussed, and their apparent capabilities and limitations are summarized. These correlations have been made to be an integral part of a computer code, ICEPERF, which has been designed to calculate iced propeller performance. Comparison with experimental propeller icing data shows generally good agreement, with the quality of the predicted results seen to be directly related to the radial icing extent of each case. The code's capability to properly predict thrust coefficient, power coefficient, and propeller efficiency is shown to be strongly dependent on the choice of correlation selected, as well as upon proper specificatioon of radial icing extent.
High Speed Friction Microscopy and Nanoscale Friction Coefficient Mapping
Bosse, James L.; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S
2014-01-01
As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for Friction Coefficient Mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true...
关于相关系数的探讨%Study of the Correlation Coefficients in Mathematical Statistics
Institute of Scientific and Technical Information of China (English)
张世强; 吕杰能; 蒋峥; 张雷
2009-01-01
讨论统计学中的线性相关系数和非线性相关系数,寻找其共性.对比研究与信息再利用.得到一个相关系数的通用公式.该公式适合于统计学中的各种数据处理.%To study the linear correlation coefficient and nonlinear correlation coefficient in statistics and find general character. To contrast the linear correlation coefficient with the nonlinear correlation coefficient in statistics and based information reused. A commonly used correlation coefficient is given. The commonly used correlation coefficient is suitable for all data analysis in statistics.
Poddar, R; Sen, P; Andrews, J T
2008-01-01
Noninvasive, non-contact and \\textit{in vivo} monitoring of blood glucose is a long needed pathology tool for saving patients from recurring pain and hassle that can accompany conventional blood glucose testing methods. Optical coherence tomography known for its high axial resolution imaging modality is adopted in this article for monitoring glucose levels in tissue like media non-invasively. Making use of changes in reduced scattering coefficient due to the refractive-index mismatch between the extracellular fluid and the cellular membranes and armed with a theoretical model, we establish a correlation between the glucose concentration and reduced scattering coefficient. The scattering coefficients are extracted from the deconvoluted interference signal by using Monte-Carlo simulation with valid approximations. A program code using NI LabVIEW(^{TM}) is developed for automation of the experiment, data acquisition and analysis.
Fully automated setup for high temperature Seebeck coefficient measurement
Patel, Ashutosh
2016-01-01
In this work, we report the fabrication of fully automated experimental setup for high temperature Seebeck coefficient ($\\alpha$) measurement. The K-type thermocouples are used to measure the average temperature of the sample and Seebeck voltage (SV) across it. The temperature dependence of the Seebeck coefficients of the thermocouple and its negative leg is taken care by using the integration method. Steady state based differential technique is used for $\\alpha$ measurement. Use of limited component and thin heater simplify the sample holder design and minimize the heat loss. The power supplied to the heater decides temperature difference across the sample and measurement is carried out by achieving the steady state. The LabVIEW based program is built to automize the whole measurement process. The complete setup is fabricated by using commonly available materials in the market. This instrument is standardized for materials with a wide range of $\\alpha$ and for the wide range of $\\Delta T$ across the specimen...
Estimation of the concordance correlation coefficient for repeated measures using SAS and R.
Carrasco, Josep L; Phillips, Brenda R; Puig-Martinez, Josep; King, Tonya S; Chinchilli, Vernon M
2013-03-01
The concordance correlation coefficient is one of the most common approaches used to assess agreement among different observers or instruments when the outcome of interest is a continuous variable. A SAS macro and R package are provided here to estimate the concordance correlation coefficient (CCC) where the design of the data involves repeated measurements by subject and observer. The CCC is estimated using U-statistics (UST) and variance components (VC) approaches. Confidence intervals and standard errors are reported along with the point estimate of the CCC. In the case of the VC approach, the linear mixed model output and variance components estimates are also provided. The performance of each function is shown by means of some examples with real data sets.
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.
Turner, Rebecca M; Prevost, A Toby; Thompson, Simon G
2004-04-30
The sample size required for a cluster randomized trial depends on the magnitude of the intracluster correlation coefficient (ICC). The usual sample size calculation makes no allowance for the fact that the ICC is not known precisely in advance. We develop methods which allow for the uncertainty in a previously observed ICC, using a variety of distributional assumptions. Distributions for the power are derived, reflecting this uncertainty. Further, the observed ICC in a future study will not equal its true value, and we consider the impact of this on power. We implement calculations within a Bayesian simulation approach, and provide one simplification that can be performed using simple simulation within spreadsheet software. In our examples, recognizing the uncertainty in a previous ICC estimate decreases expected power, especially when the power calculated naively from the ICC estimate is high. To protect against the possibility of low power, sample sizes may need to be very substantially increased. Recognizing the variability in the future observed ICC has little effect if prior uncertainty has already been taken into account. We show how our method can be extended to the case in which multiple prior ICC estimates are available. The methods presented in this paper can be used by applied researchers to protect against loss of power, or to choose a design which reduces the impact of uncertainty in the ICC. Copyright 2004 John Wiley & Sons, Ltd.
Wang, Jifei; Sun, Meili; Liu, Dawei; Hu, Xiaoshu; Pui, Margaret H; Meng, Quanfei; Gao, Zhenhua
2017-08-01
Background Neoadjuvant chemotherapy has made limb-salvage surgery possible for the patients with osteosarcoma. Diffusion-weighted magnetic resonance imaging (DWI) has been used to monitor chemotherapy response. Purpose To correlate the apparent diffusion coefficient (ADC) values with histopathology subtypes of osteosarcoma after neoadjuvant chemotherapy. Material and Methods Twelve patients with osteoblastic (n = 7), chondroblastic (n = 4), and fibroblastic (n = 1) osteosarcomas underwent post-chemotherapy DWI before limb-salvage surgery. ADCs corresponding to 127 histological tissue samples from the 12 resected specimens were compared to histological features. Results The mean ADC value of non-cartilaginous viable tumor (38/91, ADC = 1.22 ± 0.03 × 10(-3 )mm(2)/s) was significantly ( P 0.05) different between viable cartilaginous tumor and cystic/hemorrhagic necrosis. Conclusion DWI allows assessment of tumor necrosis after neoadjuvant chemotherapy by ADC differences between viable tumor and necrosis in fibroblastic and osteoblastic osteosarcomas whereas viable chondroblastic osteosarcoma has high ADC and cannot be distinguished reliably from necrosis.
Wang, Jianji; Zheng, Nanning
2013-09-01
Fractal image compression (FIC) is an image coding technology based on the local similarity of image structure. It is widely used in many fields such as image retrieval, image denoising, image authentication, and encryption. FIC, however, suffers from the high computational complexity in encoding. Although many schemes are published to speed up encoding, they do not easily satisfy the encoding time or the reconstructed image quality requirements. In this paper, a new FIC scheme is proposed based on the fact that the affine similarity between two blocks in FIC is equivalent to the absolute value of Pearson's correlation coefficient (APCC) between them. First, all blocks in the range and domain pools are chosen and classified using an APCC-based block classification method to increase the matching probability. Second, by sorting the domain blocks with respect to APCCs between these domain blocks and a preset block in each class, the matching domain block for a range block can be searched in the selected domain set in which these APCCs are closer to APCC between the range block and the preset block. Experimental results show that the proposed scheme can significantly speed up the encoding process in FIC while preserving the reconstructed image quality well.
Bodryakov, V. Yu.; Bykov, A. A.
2016-05-01
The correlation between the volumetric thermal expansion coefficient β( T) and the heat capacity C( T) of aluminum is considered in detail. It is shown that a clear correlation is observed in a significantly wider temperature range, up to the melting temperature of the metal, along with the low-temperature range where it is linear. The significant deviation of dependence β( C) from the low-temperature linear behavior is observed up to the point where the heat capacity achieves the classical Dulong-Petit limit of 3 R ( R is the universal gas constant).
Diagnosis method based on wavelet coefficient scale relativity correlation dimension for fault
Institute of Scientific and Technical Information of China (English)
2008-01-01
Correlation dimension as a tool to describe machinery condition is introduced.Vibration signals of the fan under different working conditions are analyzed using a threshold filtering algorithm based on the region relativity of the wavelet coefficients for reducing noise.The result shows that the characteristics of the signal could be preserved completely.The correlation dimension is able to identify conditions of the fan with faults compared with the normal condition,thereby providing an effective technology for condition monitoring and fault diagnosis of mechanical equipment.
Ground reaction force analysed with correlation coefficient matrix in group of stroke patients.
Szczerbik, Ewa; Krawczyk, Maciej; Syczewska, Małgorzata
2014-01-01
Stroke is the third cause of death in contemporary society and causes many disorders. Clinical scales, ground reaction force (GRF) and objective gait analysis are used for assessment of patient's rehabilitation progress during treatment. The goal of this paper is to assess whether signal correlation coefficient matrix applied to GRF can be used for evaluation of the status of post-stroke patients. A group of patients underwent clinical assessment and instrumented gait analysis simultaneously three times. The difference between components of patient's GRF (vertical, fore/aft, med/lat) and normal ones (reference GRF of healthy subjects) was calculated as correlation coefficient. Patients were divided into two groups ("worse" and "better") based on the clinical functional scale tests done at the beginning of rehabilitation process. The results obtained by these two groups were compared using statistical analysis. An increase of median value of correlation coefficient is observed in all components of GRF, but only in non-paretic leg. Analysis of GRF signal can be helpful in assessment of post-stroke patients during rehabilitation. Improvement in stroke patients was observed in non-paretic leg of the "worse" group. GRF analysis should not be the only tool for objective validation of patient's improvement, but could be used as additional source of information.
Directory of Open Access Journals (Sweden)
Mohammad Mizanur RAHMAN
2016-06-01
Full Text Available Digital terrestrial television (DTV covers an area with radius as large as 60 km. Federal Communications Commission (FCC and Office of Communications (Ofcom suggests detection of DTV signal at signal strength of as low as -114 dBm and -120 dBm respectively. Thus, detection of DTV signals in low signal-to-noise ratio (SNR is vital. Continual pilot (CP positions in all the DTV signals are fixed. Digital Video Broadcasting Terrestrial (DVB-T, a DTV standard, is followed by most of the countries of the world. In this paper we propose a correlation based CP detection which can detect a DVB-T signal at low SNR. One CP carrier was generated at the receiver which was correlated with the received orthogonal frequency division multiplexing (OFDM signal sequence. The correlation coefficient was then compared with a threshold correlation coefficient to identify the existence of the CP to detect the presence of a DVB-T signal and thereby spectrum hole. It was found from the simulation study for additive white Gaussian noise (AWGN channel that signal detection at low SNR is possible compared to the time domain symbol cross-correlation (TDSC method.
Zinchuk, Vadim; Wu, Yong; Grossenbacher-Zinchuk, Olga; Stefani, Enrico
2011-09-15
Interactions of proteins are examined by detecting their overlap using fluorescent markers. The observed overlap is then quantified to serve as a measure of spatial correlation. A major drawback of this approach is that it can produce false values because of the properties of the image background. To remedy this, we provide a protocol to reduce the contribution of image background and then apply a protein proximity index (PPI) and correlation coefficient to estimate colocalization. Background heterogeneity is reduced by the median filtering procedure, comprising two steps, to reduce random noise and background, respectively. Alternatively, background can be reduced by advanced thresholding. PPI provides separate values for each channel to characterize the contribution of each protein, whereas correlation coefficient determines the overall colocalization. The protocol is demonstrated using computer-simulated and real biological images. It minimizes human bias and can be universally applied to various cell types in which there is a need to understand protein-protein interactions. Background reductions require 3-5 min per image. Quantifications take <1 min. The entire procedure takes approximately 15-30 min.
Chen, Lihua; Liu, Min; Bao, Jing; Xia, Yunbao; Zhang, Jiuquan; Zhang, Lin; Huang, Xuequan; Wang, Jian
2013-01-01
To perform a meta-analysis exploring the correlation between the apparent diffusion coefficient (ADC) and tumor cellularity in patients. We searched medical and scientific literature databases for studies discussing the correlation between the ADC and tumor cellularity in patients. Only studies that were published in English or Chinese prior to November 2012 were considered for inclusion. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. Sensitivity and subgroup analyses were performed to investigate potential heterogeneity. Of 189 studies, 28 were included in the meta-analysis, comprising 729 patients. The pooled r for all studies was -0.57 (95% CI: -0.62, -0.52), indicating notable heterogeneity (Pcorrelation between the ADC and cellularity for brain tumors. There was no notable evidence of publication bias. There is a strong negative correlation between the ADC and tumor cellularity in patients, particularly in the brain. However, larger, prospective studies are warranted to validate these findings in other cancer types.
Ayatollahi, Majid R.; Moazzami, Mostafa
2017-03-01
The digital image correlation (DIC) method is used to obtain the coefficients of higher-order terms in the Williams expansion in a compact tension (CT) specimens made of polymethyl methacrylate (PMMA). The displacement field is determined by the correlation between reference image (i.e., before deformation) and deformed image. The part of displacements resulting from rigid body motion and rotation is eliminated from the displacement field. For a large number of points in the vicinity of the crack tip, an over-determined set of simultaneous linear equations is collected, and by using the fundamental concepts of the least-squares method, the coefficients of the Williams expansion are calculated for pure mode I conditions. The experimental results are then compared with the numerical results calculated by finite element method (FEM). Very good agreement is shown to exist between the DIC and FE results confirming the effectiveness of the DIC technique in obtaining the coefficients of higher order terms of Williams series expansion from the displacement field around the crack tip.
Correlation and path coefficient analysis for yield and its components in vegetable soybean
Directory of Open Access Journals (Sweden)
Teerawat Sarutayophat
2012-07-01
Full Text Available The associations of yield and its components offer important information in breeding plants. A study was conductedat the experimental field of the Faculty of Agricultural Technology, King Mongkut’s Institute of Technology Ladkrabang,Bangkok on 22 genotypes of the vegetable soybean to determine the association of yield and its components. The associationwas analyzed by correlation coefficient, and further subjected by path coefficient analysis to estimate direct and indirecteffects of each character on pod yield. Positive and significant correlation were found between the plant height and numberof marketable pods/plant (0.821**, plant height and marketable pod yield (0.520*, and number of marketable pods/plant andmarketable pod yield (0.822**. Negative and significance was determined between the plant height and green pod weight(-0.620**, and number of marketable pods/plant and green pod weight (-0.588**. Direct effects of the number of marketablepods/plant and green pod weight on marketable pod yield were positive and significant with path coefficients of 1.310** and0.707**, respectively. Indirect effect of the plant height on marketable pod yield through its association with number ofmarketable pods/plant was positive and significant (1.075**. The results of this study suggested that the number of marketablepods/plant, green pod weight and plant height were important characters that should be taken into account as selectioncriteria in improving marketable pod yield of the vegetable soybean.
Energy Technology Data Exchange (ETDEWEB)
Vahidi, B.; Ghaffarzadeh, N.; Hosseinian, S.H. [Dept. of Electrical Engineering, Amirkabir University of Technology, Tehran (Iran)
2010-09-15
In this paper a new method based on discrete wavelet transform and correlation coefficient is presented for digital differential protection. The algorithm includes offline and online operations. In offline operation, discrete wavelet transform is used to decompose typical three-phase differential currents for inrush current. Then an index is defined and computed. The index is based on the sum of the energy of detail coefficients at level 5 of three-phase differential currents at each half cycle. The online operation consists of capturing the three-phase differential currents using 10 kHz sampling rate, decomposing it by db1. Finally, the inrush current and internal fault is detected based on correlation coefficients of the computed index of pre-stored typical inrush current and a recorded indistinct signal. The effectiveness of the approach is tested using numerous inrush and internal fault currents. Simulations are used to confirm the aptness and the capability of the proposed method to discriminate inrush current from internal fault. (author)
Cao, Guangxi; He, Cuiting; Xu, Wei
2016-03-01
This study investigates the correlation between weather and agricultural futures markets on the basis of detrended cross-correlation analysis (DCCA) cross-correlation coefficients and q-dependent cross-correlation coefficients. In addition, detrended fluctuation analysis (DFA) is used to measure extreme weather and thus analyze further the effect of this condition on agricultural futures markets. Cross-correlation exists between weather and agricultural futures markets on certain time scales. There are some correlations between temperature and soybean return associated with medium amplitudes. Under extreme weather conditions, weather exerts different influences on different agricultural products; for instance, soybean return is greatly influenced by temperature, and weather variables exhibit no effect on corn return. Based on the detrending moving-average cross-correlation analysis (DMCA) coefficient and DFA regression results are similar to that of DCCA coefficient.
SPSS and SAS programs for comparing Pearson correlations and OLS regression coefficients.
Weaver, Bruce; Wuensch, Karl L
2013-09-01
Several procedures that use summary data to test hypotheses about Pearson correlations and ordinary least squares regression coefficients have been described in various books and articles. To our knowledge, however, no single resource describes all of the most common tests. Furthermore, many of these tests have not yet been implemented in popular statistical software packages such as SPSS and SAS. In this article, we describe all of the most common tests and provide SPSS and SAS programs to perform them. When they are applicable, our code also computes 100 × (1 - α)% confidence intervals corresponding to the tests. For testing hypotheses about independent regression coefficients, we demonstrate one method that uses summary data and another that uses raw data (i.e., Potthoff analysis). When the raw data are available, the latter method is preferred, because use of summary data entails some loss of precision due to rounding.
Dong, Shiqing; You, Minghai; Chen, Jianling; Zhou, Jie; Xie, Shusen; Yang, Hongqin
2017-06-01
The fluidity of proteins and lipids on cell membrane plays an important role in cell’s physiological functions. Fluorescence correlation spectroscopy (FCS) is an effective technique to detect the rapid dynamic behaviors of proteins and/or lipids in living cells. In this study, we used the rhodamine6G solution to optimize the FCS system. And, cholera toxin B subunit (CT-B) was used to label ganglioside on living Hela cell membranes. The diffusion time and coefficients of ganglioside can be obtained through fitting the autocorrelation curve based on the model of two-dimensional cell membrane. The results showed that the diffusion coefficients of ganglioside distributed within a wide range. It revealed the lateral diffusion of lipids on cell membrane was inhomogeneous, which was due to different microstructures of cytoplasmic membrane. The study provides a helpful method for further studying the dynamic characteristics of proteins and lipids molecules on living cell membrane.
de Winter, Joost C F; Gosling, Samuel D; Potter, Jeff
2016-09-01
The Pearson product–moment correlation coefficient (rp) and the Spearman rank correlation coefficient (rs) are widely used in psychological research. We compare rp and rs 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, rp and rs have similar expected values but rs is more variable, especially when the correlation is strong. However, when the variables have high kurtosis, rp is more variable than rs. 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, rp had lower variability than rs in the psychometric dataset. In the survey datasets with heavy-tailed variables in particular, rs had lower variability than rp, and often corresponded more accurately to the population Pearson correlation coefficient (Rp) than rp did. The simulations and the sampling studies showed that variability in terms of standard deviations can be reduced by about 20% by choosing rs instead of rp. In comparison, increasing the sample size by a factor of 2 results in a 41% reduction of the standard deviations of rs and rp. In conclusion, rp is suitable for light-tailed distributions, whereas rs is preferable when variables feature heavy-tailed distributions or when outliers are present, as is often the case in psychological research.
Frontal Face Detection using Haar Wavelet Coefficients and Local Histogram Correlation
Directory of Open Access Journals (Sweden)
Iwan Setyawan
2011-12-01
Full Text Available Face detection is the main building block on which all automatic systems dealing with human faces is built. For example, a face recognition system must rely on face detection to process an input image and determine which areas contain human faces. These areas then become the input for the face recognition system for further processing. This paper presents a face detection system designed to detect frontal faces. The system uses Haar wavelet coefficients and local histogram correlation as differentiating features. Our proposed system is trained using 100 training images. Our experiments show that the proposed system performed well during testing, achieving a detection rate of 91.5%.
Yu, Xue; Lee, Elaine Yuen Phin; Lai, Vincent; Chan, Queenie
2014-07-01
To evaluate the correlation between standardized uptake value (SUV) (tissue metabolism) and apparent diffusion coefficient (ADC) (water diffusivity) in peritoneal metastases. Patients with peritoneal dissemination detected on (18)F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) were prospectively recruited for MRI examinations with informed consent and the study was approved by the local Institutional Review Board. FDG-PET/CT, diffusion-weighted imaging (DWI), MRI, and DWI/MRI images were independently reviewed by two radiologists based on visual analysis. SUVmax/SUVmean and ADCmin/ADCmean were obtained manually by drawing ROIs over the peritoneal metastases on FDG-PET/CT and DWI, respectively. Diagnostic characteristics of each technique were evaluated. Pearson's coefficient and McNemar and Kappa tests were used for statistical analysis. Eight patients were recruited for this prospective study and 34 peritoneal metastases were evaluated. ADCmean was significantly and negatively correlated with SUVmax (r = -0.528, P = 0.001) and SUVmean (r = -0.548, P = 0.001). ADCmin had similar correlation with SUVmax (r = -0.508, P = 0.002) and SUVmean (r = -0.513, P = 0.002). DWI/MRI had high diagnostic performance (accuracy = 98%) comparable to FDG-PET/CT, in peritoneal metastasis detection. Kappa values were excellent for all techniques. There was a significant inverse correlation between SUV and ADC. © 2013 Wiley Periodicals, Inc.
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.
Koral, Korgün; Mathis, Derek; Gimi, Barjor; Gargan, Lynn; Weprin, Bradley; Bowers, Daniel C; Margraf, Linda
2013-08-01
To test whether there is correlation between cell densities and apparent diffusion coefficient (ADC) metrics of common pediatric cerebellar tumors. This study was reviewed for issues of patient safety and confidentiality and was approved by the Institutional Review Board of the University of Texas Southwestern Medical Center and was compliant with HIPAA. The need for informed consent was waived. Ninety-five patients who had preoperative magnetic resonance imaging and surgical pathologic findings available between January 2003 and June 2011 were included. There were 37 pilocytic astrocytomas, 34 medulloblastomas (23 classic, eight desmoplastic-nodular, two large cell, one anaplastic), 17 ependymomas (13 World Health Organization [WHO] grade II, four WHO grade III), and seven atypical teratoid rhabdoid tumors. ADCs of solid tumor components and normal cerebellum were measured. Tumor-to-normal brain ADC ratios (hereafter, ADC ratio) were calculated. The medulloblastomas and ependymomas were subcategorized according to the latest WHO classification, and tumor cellularity was calculated. Correlation was sought between cell densities and mean tumor ADCs, minimum tumor ADCs, and ADC ratio. When all tumors were considered together, negative correlation was found between cellularity and mean tumor ADCs (ρ = -0.737, P correlation between cellularity and ADC ratio. Negative correlation was found between cellularity and minimum tumor ADC in atypical teratoid rhabdoid tumors (ρ = -0.786, P correlation was found between cellularity and mean tumor ADC and ADC ratio. There was no correlation between the ADC metrics and cellularity of the pilocytic astrocytomas, medulloblastomas, and ependymomas. Negative correlation was found between cellularity and ADC metrics of common pediatric cerebellar tumors. Although ADC metrics are useful in the preoperative diagnosis of common pediatric cerebellar tumors and this utility is generally attributed to differences in cellularity of tumors
Systematic bias of correlation coefficient may explain negative accuracy of genomic prediction.
Zhou, Yao; Vales, M Isabel; Wang, Aoxue; Zhang, Zhiwu
2017-09-01
Accuracy of genomic prediction is commonly calculated as the Pearson correlation coefficient between the predicted and observed phenotypes in the inference population by using cross-validation analysis. More frequently than expected, significant negative accuracies of genomic prediction have been reported in genomic selection studies. These negative values are surprising, given that the minimum value for prediction accuracy should hover around zero when randomly permuted data sets are analyzed. We reviewed the two common approaches for calculating the Pearson correlation and hypothesized that these negative accuracy values reflect potential bias owing to artifacts caused by the mathematical formulas used to calculate prediction accuracy. The first approach, Instant accuracy, calculates correlations for each fold and reports prediction accuracy as the mean of correlations across fold. The other approach, Hold accuracy, predicts all phenotypes in all fold and calculates correlation between the observed and predicted phenotypes at the end of the cross-validation process. Using simulated and real data, we demonstrated that our hypothesis is true. Both approaches are biased downward under certain conditions. The biases become larger when more fold are employed and when the expected accuracy is low. The bias of Instant accuracy can be corrected using a modified formula. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Dunning, David; Helzer, Erik G
2014-03-01
Zell and Krizan (2014, this issue) provide a comprehensive yet incomplete portrait of the factors influencing accurate self-assessment. This is no fault of their own. Much work on self-accuracy focuses on the correlation coefficient as the measure of accuracy, but it is not the only way self-accuracy can be measured. As such, its use can provide an incomplete and potentially misleading story. We urge researchers to explore measures of bias as well as correlation, because there are indirect hints that each respond to a different psychological dynamic. We further entreat researchers to develop other creative measures of accuracy and not to forget that self-accuracy may come not only from personal knowledge but also from insight about human nature more generally.
Directory of Open Access Journals (Sweden)
Atefeh Goshvarpour
2012-04-01
Full Text Available Meditation is a practice of concentrated focus upon the breath in order to still the mind. In this paper we have investigated an algorithm to classify rest and meditation, by processing of electroencephalogram (EEG signals through the Wavelet and nonlinear methods. For this purpose, two types of EEG time series (before, and during meditation of 25 healthy women are collected in the meditation clinic in Mashhad. Correlation dimension and Wavelet coefficients at the forth decomposition level of EEG signals in Fz, Cz and Pz are extracted and used as an input of different classifiers. In order to evaluate performance of the classifiers, the classification accuracies and mean square error (MSE of the classifiers were examined. The results show that the Fisher discriminant and Parzen classifier trained on both composite features obtain higher accuracy than that of the others. The total classification accuracy of the Fisher discriminant and Parzen classifier applying Wavelet coefficients was 85.02% and 84.75%, respectively which is raised to 92.37% in both classifiers using Correlation dimensions.
Hladni Nada; Miklič Vladimir; Mijić Anto; Jocić Siniša; Miladinović Dragana
2015-01-01
The most important criteria for introducing new confectionary hybrids into the production is high protein yield. Path coefficient analysis was used to obtain information on direct and indirect effects of studied traits (seed oil content, kernel oil content, seed yield, kernel protein content, mass of 1000 seeds, kernel ratio and hull ratio) on protein yield. The research was conducted during three vegetation seasons, on 22 experimental confectionary sunflow...
PREPARATION OF HIGH THERMAL EXPANSION COEFFICIENT PORCELAINS FUSED TO METALS
Institute of Scientific and Technical Information of China (English)
J.P. Yang; J.Q. Wu
2003-01-01
Usually the thermal expansion coefficients (TEC) of metals are higher than that of porcelains. In order to match the TECs in the case of coating porcelains on metals, high TEC porcelains are needed. In this research, the high TEC phase leucite(KAlSi2 O6) in the high TEC porcelain was prepared by sol-gel method. The crystal size of leucite made by sol-gel is about 77nm through controlling the process parameters. The process from xerogel to leucite was investigated by means of DSC (differential scanning calorimetry), TG (thermogravimetry), XRD ( X-ray diffraction) and IR(infrared absorption spectrum). Leucite had been detected after the gel was treated at 900°C, this formation temperature is about 250°C lower than that of melting method.The porcelain made from 50% of the leucite powder and 50%o of low fused temperature frit has an average TEC of 19.2× 10-6/° C from room temperature to 450°C, which is much higher than the common porcelains.
Edjabou, Maklawe Essonanawe; Martín-Fernández, Josep Antoni; Scheutz, Charlotte; Astrup, Thomas Fruergaard
2017-09-04
Data for fractional solid waste composition provide relative magnitudes of individual waste fractions, the percentages of which always sum to 100, thereby connecting them intrinsically. Due to this sum constraint, waste composition data represent closed data, and their interpretation and analysis require statistical methods, other than classical statistics that are suitable only for non-constrained data such as absolute values. However, the closed characteristics of waste composition data are often ignored when analysed. The results of this study showed, for example, that unavoidable animal-derived food waste amounted to 2.21±3.12% with a confidence interval of (-4.03; 8.45), which highlights the problem of the biased negative proportions. A Pearson's correlation test, applied to waste fraction generation (kg mass), indicated a positive correlation between avoidable vegetable food waste and plastic packaging. However, correlation tests applied to waste fraction compositions (percentage values) showed a negative association in this regard, thus demonstrating that statistical analyses applied to compositional waste fraction data, without addressing the closed characteristics of these data, have the potential to generate spurious or misleading results. Therefore, ¨compositional data should be transformed adequately prior to any statistical analysis, such as computing mean, standard deviation and correlation coefficients. Copyright © 2017 Elsevier Ltd. All rights reserved.
Pairing Correlations at High Spins
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.
Raykov, Tenko; Marcoulides, George A.
2015-01-01
A latent variable modeling procedure that can be used to evaluate intraclass correlation coefficients in two-level settings with discrete response variables is discussed. The approach is readily applied when the purpose is to furnish confidence intervals at prespecified confidence levels for these coefficients in setups with binary or ordinal…
Zhou, Hong; Muellerleile, Paige; Ingram, Debra; Wong, Seok P.
2011-01-01
Intraclass correlation coefficients (ICCs) are commonly used in behavioral measurement and psychometrics when a researcher is interested in the relationship among variables of a common class. The formulas for deriving ICCs, or generalizability coefficients, vary depending on which models are specified. This article gives the equations for…
Zhou, Hong; Muellerleile, Paige; Ingram, Debra; Wong, Seok P.
2011-01-01
Intraclass correlation coefficients (ICCs) are commonly used in behavioral measurement and psychometrics when a researcher is interested in the relationship among variables of a common class. The formulas for deriving ICCs, or generalizability coefficients, vary depending on which models are specified. This article gives the equations for…
Testing Serial Correlation in Semiparametric Varying-Coefficient Partially Linear EV Models
Institute of Scientific and Technical Information of China (English)
Xue-mei Hu; Zhi-zhong Wang; Feng Liu
2008-01-01
This paper studies estimation and serial correlation test of a semiparametric varying-coefficient partially linear EV model of the form Y = Xτβ + Zτα(T) + ε,ξ = X + η with the identifying condition E[(ε,ητ)τ] = 0, Cov[(ε,ητ)τ] = σ2Iρ+1. The estimators of interested regression parameters β, and the model error variance σ2, as well as the nonparametric components α(T), are constructed. Under some regular conditions, we show that the estimators of the unknown vector β and the unknown parameter σ2 are strongly consistent and asymptotically normal and that the estimator of α(T) achieves the optimal strong convergence rate of the usual nonparametric regression. Based on these estimators and asymptotic properties, we propose the VN,p test statistic and empirical log-likelihood ratio statistic for testing serial correlation in the model. The proposed statistics are shown to have asymptotic normal or chi-square distributions under the null hypothesis of no serial correlation. Some simulation studies are conducted to illustrate the finite sample performance of the proposed tests.
Tsai, Miao-Yu
2017-04-15
The concordance correlation coefficient (CCC) is a commonly accepted measure of agreement between two observers for continuous responses. This paper proposes a generalized estimating equations (GEE) approach allowing dependency between repeated measurements over time to assess intra-agreement for each observer and inter- and total agreement among multiple observers simultaneously. Furthermore, the indices of intra-, inter-, and total agreement through variance components (VC) from an extended three-way linear mixed model (LMM) are also developed with consideration of the correlation structure of longitudinal repeated measurements. Simulation studies are conducted to compare the performance of the GEE and VC approaches for repeated measurements from longitudinal data. An application of optometric conformity study is used for illustration. In conclusion, the GEE approach allowing flexibility in model assumptions and correlation structures of repeated measurements gives satisfactory results with small mean square errors and nominal 95% coverage rates for large data sets, and when the assumption of the relationship between variances and covariances for the extended three-way LMM holds, the VC approach performs outstandingly well for all sample sizes. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.
Spatial correlation in 3D MIMO channels using fourier coefficients of power spectrums
Nadeem, Qurrat-Ul-Ain
2015-03-01
In this paper, an exact closed-form expression for the Spatial Correlation Function (SCF) is derived for the standardized three-dimensional (3D) multiple-input multiple-output (MIMO) channel. This novel SCF is developed for a uniform linear array of antennas with non-isotropic antenna patterns. The proposed method resorts to the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials to obtain a closed-form expression for the SCF for arbitrary angular distributions and antenna patterns. The resulting expression depends on the underlying angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty of the proposed method lies in the SCF being valid for any 3D propagation environment. Numerical results validate the proposed analytical expression and study the impact of angular spreads on the correlation. The derived SCF will help evaluate the performance of correlated 3D MIMO channels in the future. © 2015 IEEE.
The universal coefficient of the exact correlator of a large-$N$ matrix field theory
Katzav, Eytan
2016-01-01
Exact expressions have been proposed for correlation functions of the large-$N$ (planar) limit of the $(1+1)$-dimensional ${\\rm SU}(N)\\times {\\rm SU}(N)$ principal chiral sigma model. These were obtained with the form-factor bootstrap. The short-distance form of the two-point function of the scaling field $\\Phi(x)$, was found to be $N^{-1}\\langle {\\rm Tr}\\,\\Phi(0)^{\\dagger} \\Phi(x)\\rangle=C_{2}\\ln^{2}mx$, where $m$ is the mass gap, in agreement with the perturbative renormalization group. Here we point out that the universal coefficient $C_{2}$, is proportional to the mean first-passage time of a L\\'{e}vy flight in one dimension. This observation enables us to calculate $C_{2}=1/16\\pi$.
Big Macs and Eigenfactor Scores: Don't Let Correlation Coefficients Fool You
West, Jevin; Bergstrom, Carl
2009-01-01
The Eigenfactor Metrics provide an alternative way of evaluating scholarly journals based on an iterative ranking procedure analogous to Google's PageRank algorithm. These metrics have recently been adopted by Thomson-Reuters and are listed alongside the Impact Factor in the Journal Citation Reports. But do these metrics differ sufficiently so as to be a useful addition to the bibliometric toolbox? Davis (2008) has argued otherwise, based on his finding of a 0.95 correlation coefficient between Eigenfactor score and total citations for a sample of journals in the field of medicine. This conclusion is mistaken; here we illustrate the basic statistical fallacy to which Davis succumbed. We provide a complete analysis of the 2006 Journal Citation Reports and demonstrate that there are important differences between the information provided by the Eigenfactor Metrics and that provided by Impact Factor and Total Citations.
Directory of Open Access Journals (Sweden)
Jana Shafi
2016-09-01
Full Text Available In this paper, we discuss project scheduling with conflicting activity-resources. Several project activities require same resources but, may be scheduled with the certain lapse of time resulting in repeatedly using the same kind of resources for executing dissimilar activities. Due to the frequent usage of same resources multiple times, expenditure become more expensive and project duration extends. The problem is to find out such kind of activities which are developing implicit relations amid them. , we proposed a solution by introducing TVs (Transparent view of Scheduling model. First, we analyze and enlists activities according to required resources, categorize them and then we segregate dependent and independent activities by indicating a value. Performing Dependency test on activities by using Pearson's Correlation Coefficient (PCC to calculate the rate of relations among the ordered activities for similar resources. By using this model we can reschedule activities to avoid confusion and disordering of resources without consumption of time and capital.
Abe, Tomomi; Hashimoto, Shuji; Matsumoto, Mitsuharu
2010-02-01
epsilon-filter can reduce most kinds of noise from a single-channel noisy signal while preserving signals that vary drastically such as speech signals. It can reduce not only stationary noise but also nonstationary noise. However, it has some parameters whose values are set empirically. So far, there have been few studies to evaluate the appropriateness of the parameter settings for epsilon-filter. This paper employs the correlation coefficient of the filter output and the difference between the filter input and output as the evaluation function of the parameter setting. This paper also describes the algorithm to set the optimal parameter value of epsilon-filter automatically. To evaluate the adequateness of the obtained parameter, the mean absolute error is calculated. The experimental results show that the adequate parameter in epsilon-filter can be obtained automatically by using the proposed method.
Liu, Xuan; Ramella-Roman, Jessica C; Huang, Yong; Guo, Yuan; Kang, Jin U
2013-01-01
In this study, we propose a generic speckle simulation for optical coherence tomography (OCT) signal, by convolving the point-spread function (PSF) of the OCT system with the numerically synthesized random sample field. We validate our model and use the simulation method to study the statistical properties of cross-correlation coefficients between A-scans, which have been recently applied in transverse motion analysis by our group. The results of simulation show that oversampling is essential for accurate motion tracking; exponential decay of OCT signal leads to an underestimate of motion that can be corrected; lateral heterogeneity of sample leads to an overestimate of motion for a few pixels corresponding to the structural boundary.
Lesion area detection using source image correlation coefficient for CT perfusion imaging.
Fan Zhu; Rodriguez Gonzalez, David; Carpenter, Trevor; Atkinson, Malcolm; Wardlaw, Joanna
2013-09-01
Computer tomography (CT) perfusion imaging is widely used to calculate brain hemodynamic quantities such as cerebral blood flow, cerebral blood volume, and mean transit time that aid the diagnosis of acute stroke. Since perfusion source images contain more information than hemodynamic maps, good utilization of the source images can lead to better understanding than the hemodynamic maps alone. Correlation-coefficient tests are used in our approach to measure the similarity between healthy tissue time-concentration curves and unknown curves. This information is then used to differentiate penumbra and dead tissues from healthy tissues. The goal of the segmentation is to fully utilize information in the perfusion source images. Our method directly identifies suspected abnormal areas from perfusion source images and then delivers a suggested segmentation of healthy, penumbra, and dead tissue. This approach is designed to handle CT perfusion images, but it can also be used to detect lesion areas in magnetic resonance perfusion images.
Liang, Yunyun; Liu, Sanyang; Zhang, Shengli
2016-12-01
Apoptosis, or programed cell death, plays a central role in the development and homeostasis of an organism. Obtaining information on subcellular location of apoptosis proteins is very helpful for understanding the apoptosis mechanism. The prediction of subcellular localization of an apoptosis protein is still a challenging task, and existing methods mainly based on protein primary sequences. In this paper, we introduce a new position-specific scoring matrix (PSSM)-based method by using detrended cross-correlation (DCCA) coefficient of non-overlapping windows. Then a 190-dimensional (190D) feature vector is constructed on two widely used datasets: CL317 and ZD98, and support vector machine is adopted as classifier. To evaluate the proposed method, objective and rigorous jackknife cross-validation tests are performed on the two datasets. The results show that our approach offers a novel and reliable PSSM-based tool for prediction of apoptosis protein subcellular localization.
Directory of Open Access Journals (Sweden)
Haddad Samira M
2012-09-01
Full Text Available Abstract Background The purpose of the study was to evaluate intraclass correlation coefficients (ICC of variables concerning personal characteristics, structure, outcome and process in the Brazilian Network for Surveillance of Severe Maternal Morbidity study conducted to identify severe maternal morbidity/near miss cases using the World Health Organization criteria. Method It was a cross-sectional, multicenter study involving 27 hospitals providing care for pregnant women in Brazil. Cluster size and the mean size of the primary sampling unit were described. Estimated prevalence rates, ICC, their respective 95% confidence intervals, the design effect and the mean cluster size were presented for each variable. Results Overall, 9,555 cases of severe maternal morbidity (woman admitted with potentially life-threatening conditions, near miss events or death were included in the study. ICC ranged from Conclusions These results may be used to design new cluster trials in maternal and perinatal health and to help calculate sample sizes.
Ren, Da-Bing; Yang, Zhao-Hui; Liang, Yi-Zeng; Ding, Qiong; Chen, Chen; Ouyang, Mei-Lan
2013-08-02
Selection of a suitable solvent system is the first and foremost step for a successful counter-current chromatography (CCC) separation. In this paper, a thermodynamic model, nonrandom two-liquid segment activity coefficient model (NRTL-SAC) which uses four types of conceptual segments to describe the effective surface interactions for each solvent and solute molecule, was employed to correlate and predict the partition coefficients (K) of a given compound in a specific solvent system. Then a suitable solvent system was selected according to the predicted partition coefficients. Three solvent system families, heptane/methanol/water, heptane/ethyl acetate/methanol/water (Arizona) and hexane/ethyl acetate/methanol/water, and several solutes were selected to investigate the effectiveness of the NRTL-SAC model for predicting the partition coefficients. Comparison between experimental results and predicted results showed that the NRTL-SAC model is of potential for estimating the K value of a given compound. Also a practical separation case on magnolol and honokiol suggests the NRTL-SAC model is effective, reliable and practical for the purpose of predicting partition coefficients and selecting a suitable solvent system for CCC separation. Copyright © 2013. Published by Elsevier B.V.
Inoue, Chie; Fujii, Shinya; Kaneda, Sachi; Fukunaga, Takeru; Kaminou, Toshio; Kigawa, Junzo; Harada, Tasuku; Ogawa, Toshihide
2015-01-01
To correlate the apparent diffusion coefficient (ADC) of endometrioid carcinoma with histological tumor grade and degree of myometrial invasion. 3T diffusion-weighted (DW) magnetic resonance (MR) images of 63 patients were retrospectively reviewed. Two readers measured tumor ADC according to a freehand region of interest (ROI) and a round ROI. Mean and minimum ADCs were correlated with prognostic parameters. The minimum ADC was 0.64 × 10(-3) mm(2)/s for grade 1 (G1, n = 42), 0.62 for grade 2 (G2, n = 14), 0.46 for grade 3 (G3, n = 7) on freehand ROI. There were significant differences between G1 and G3 (P = 0.007), and G2 and G3 (P = 0.038). No significant correlation was found between tumor grade and mean ADC (0.85 for G1, 0.82 for G2, and 0.72 for G3, P = 0.166). The minimum ADC was significantly lower for patients with deep (n = 21, 0.54) than for those with superficial (n = 39, 0.65) myometrial invasion. Conversely, mean ADC did not differ significantly (0.84 for superficial and 0.78 for deep myometrial invasion, P = 0.081). The same tendency was shown on round ROI. The minimum ADC correlates with prognostic parameters of endometrial carcinoma more strongly than mean ADC. Lower minimum ADC is associated with higher histological tumor grade and higher degree of myometrial invasion. © 2013 Wiley Periodicals, Inc.
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Stella Crosara Lopes
2009-04-01
Full Text Available The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs of the metals and ceramics. Verabond (VB Ni-Cr-Be alloy, Verabond II (VB2, Ni-Cr alloy, Pors-on 4 (P, Pd-Ag alloy, and IPS (I and Duceram (D ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01 for the MCBS test results (MPa, with PI showing higher MCBS (67.72 than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1 differences were: VBI (0.54, VBD (1.33, VB2I (-0.14, VB2D (0.63, PI (1.84 and PD (2.62. Pearson's correlation test (r=0.17 was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.
Kunz, Cornelia U; Stallard, Nigel; Parsons, Nicholas; Todd, Susan; Friede, Tim
2017-03-01
Regulatory authorities require that the sample size of a confirmatory trial is calculated prior to the start of the trial. However, the sample size quite often depends on parameters that might not be known in advance of the study. Misspecification of these parameters can lead to under- or overestimation of the sample size. Both situations are unfavourable as the first one decreases the power and the latter one leads to a waste of resources. Hence, designs have been suggested that allow a re-assessment of the sample size in an ongoing trial. These methods usually focus on estimating the variance. However, for some methods the performance depends not only on the variance but also on the correlation between measurements. We develop and compare different methods for blinded estimation of the correlation coefficient that are less likely to introduce operational bias when the blinding is maintained. Their performance with respect to bias and standard error is compared to the unblinded estimator. We simulated two different settings: one assuming that all group means are the same and one assuming that different groups have different means. Simulation results show that the naïve (one-sample) estimator is only slightly biased and has a standard error comparable to that of the unblinded estimator. However, if the group means differ, other estimators have better performance depending on the sample size per group and the number of groups.
Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes
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Pezo Milada L.
2016-01-01
Full Text Available This paper presents CFD (Computational Fluid Dynamics approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin and Rohsenow correlations. The presented numerical modeling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface. [Projekat Ministarstva nauke Republike Srbije, br. 174014
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Sarafraz M.M.
2012-01-01
Full Text Available Pool boiling heat transfer coefficient of monoethylene glycol (MEG, diethylene glycol (DEG and water ternary mixtures has been experimentally measured up to heat flux 114 kW/m2 at various volumetric concentrations of MEG and DEG. As expected, heat transfer coefficient was strongly taken as a direct function of heat flux. Existing well-known correlations are shown to be unable to predict the acceptable values for the tested ternary mixtures, particularly at different concentrations of MEG and DEG. Furthermore, a new modified correlation is developed on the basis of the Stephan - Preußer correlation that predicts the values of heat transfer coefficients with absolute average error of about 7% that is reasonable and acceptable values in compare to other existing correlations.
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Jun Ye
2013-03-01
Full Text Available A single valued neutrosophic set (SVNS, which is the subclass of a neutrosophic set, can be considered as a powerful tool to express the indeterminate and inconsistent information in the process of decision making. Then, correlation is one of the most broadly applied indices in many fields and also an important measure in data analysis and classification, pattern recognition, decision making and so on. Therefore, we propose another form of correlation coefficient between SVNSs and establish a multiple attribute decision making method using the correlation coefficient of SVNSs under single valued neutrosophic environment. Through the weighted correlation coefficient between each alternative and the ideal alternative, the ranking order of all alternatives can be determined and the best alternative can be easily identified as well. Finally, two illustrative examples are employed to illustrate the actual applications of the proposed decision-making approach.
The transmission coefficient distribution of highly scattering sparse random media
Jin, Curtis; Nadakuditi, Raj Rao; Michielssen, Eric
2015-01-01
We consider the distribution of the transmission coefficients, i.e. the singular values of the modal transmission matrix, for 2D random media with periodic boundary conditions composed of a large number of point-like non-absorbing scatterers. The scatterers are placed at random locations in the medium and have random refractive indices that are drawn from an arbitrary, known distribution. We construct a randomized model for the scattering matrix that retains scatterer dependent properties ess...
Liang, Rong; Zhou, Shu-dong; Li, Li-xia; Zhang, Jun-guo; Gao, Yan-hui
2013-09-01
This paper aims to achieve Bootstraping in hierarchical data and to provide a method for the estimation on confidence interval(CI) of intraclass correlation coefficient(ICC).First, we utilize the mixed-effects model to estimate data from ICC of repeated measurement and from the two-stage sampling. Then, we use Bootstrap method to estimate CI from related ICCs. Finally, the influences of different Bootstraping strategies to ICC's CIs are compared. The repeated measurement instance show that the CI of cluster Bootsraping containing the true ICC value. However, when ignoring the hierarchy characteristics of data, the random Bootsraping method shows that it has the invalid CI. Result from the two-stage instance shows that bias observed between cluster Bootstraping's ICC means while the ICC of the original sample is the smallest, but with wide CI. It is necessary to consider the structure of data as important, when hierarchical data is being resampled. Bootstrapping seems to be better on the higher than that on lower levels.
A Bayesian estimate of the concordance correlation coefficient with skewed data.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2015-01-01
Concordance correlation coefficient (CCC) is one of the most popular scaled indices used to evaluate agreement. Most commonly, it is used under the assumption that data is normally distributed. This assumption, however, does not apply to skewed data sets. While methods for the estimation of the CCC of skewed data sets have been introduced and studied, the Bayesian approach and its comparison with the previous methods has been lacking. In this study, we propose a Bayesian method for the estimation of the CCC of skewed data sets and compare it with the best method previously investigated. The proposed method has certain advantages. It tends to outperform the best method studied before when the variation of the data is mainly from the random subject effect instead of error. Furthermore, it allows for greater flexibility in application by enabling incorporation of missing data, confounding covariates, and replications, which was not considered previously. The superiority of this new approach is demonstrated using simulation as well as real-life biomarker data sets used in an electroencephalography clinical study. The implementation of the Bayesian method is accessible through the Comprehensive R Archive Network.
Aly, Sharif S; Zhao, Jianyang; Li, Ben; Jiang, Jiming
2014-01-01
The Intraclass Correlation Coefficient (ICC) is commonly used to estimate the similarity between quantitative measures obtained from different sources. Overdispersed data is traditionally transformed so that linear mixed model (LMM) based ICC can be estimated. A common transformation used is the natural logarithm. The reliability of environmental sampling of fecal slurry on freestall pens has been estimated for Mycobacterium avium subsp. paratuberculosis using the natural logarithm transformed culture results. Recently, the negative binomial ICC was defined based on a generalized linear mixed model for negative binomial distributed data. The current study reports on the negative binomial ICC estimate which includes fixed effects using culture results of environmental samples. Simulations using a wide variety of inputs and negative binomial distribution parameters (r; p) showed better performance of the new negative binomial ICC compared to the ICC based on LMM even when negative binomial data was logarithm, and square root transformed. A second comparison that targeted a wider range of ICC values showed that the mean of estimated ICC closely approximated the true ICC.
Sterling, Sarah M; Allgeyer, Edward S; Fick, Jörg; Prudovsky, Igor; Mason, Michael D; Neivandt, David J
2013-06-25
Model cellular membranes enable the study of biological processes in a controlled environment and reduce the traditional challenges associated with live or fixed cell studies. However, model membrane systems based on the air/water or oil/solution interface do not allow for incorporation of transmembrane proteins or for the study of protein transport mechanisms. Conversely, a phospholipid bilayer deposited via the Langmuir-Blodgett/Langmuir-Schaefer method on a hydrogel layer is potentially an effective mimic of the cross section of a biological membrane and facilitates both protein incorporation and transport studies. Prior to application, however, such membranes must be fully characterized, particularly with respect to the phospholipid bilayer phase transition temperature. Here we present a detailed characterization of the phase transition temperature of the inner and outer leaflets of a chitosan supported model membrane system. Specifically, the lateral diffusion coefficient of each individual leaflet has been determined as a function of temperature. Measurements were performed utilizing z-scan fluorescence correlation spectroscopy (FCS), a technique that yields calibration-free diffusion information. Analysis via the method of Wawrezinieck and co-workers revealed that phospholipid diffusion changes from raftlike to free diffusion as the temperature is increased-an insight into the dynamic behavior of hydrogel supported membranes not previously reported.
Demetrashvili, Nino; Van den Heuvel, Edwin R
2015-06-01
This work is motivated by a meta-analysis case study on antipsychotic medications. The Michaelis-Menten curve is employed to model the nonlinear relationship between the dose and D2 receptor occupancy across multiple studies. An intraclass correlation coefficient (ICC) is used to quantify the heterogeneity across studies. To interpret the size of heterogeneity, an accurate estimate of ICC and its confidence interval is required. The goal is to apply a recently proposed generic beta-approach for construction the confidence intervals on ICCs for linear mixed effects models to nonlinear mixed effects models using four estimation methods. These estimation methods are the maximum likelihood, second-order generalized estimating equations and two two-step procedures. The beta-approach is compared with a large sample normal approximation (delta method) and bootstrapping. The confidence intervals based on the delta method and the nonparametric percentile bootstrap with various resampling strategies failed in our settings. The beta-approach demonstrates good coverages with both two-step estimation methods and consequently, it is recommended for the computation of confidence interval for ICCs in nonlinear mixed effects models for small studies.
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Mahapatra Rajendra
2011-06-01
Full Text Available Abstract Background Public health interventions are increasingly evaluated using cluster-randomised trials in which groups rather than individuals are allocated randomly to treatment and control arms. Outcomes for individuals within the same cluster are often more correlated than outcomes for individuals in different clusters. This needs to be taken into account in sample size estimations for planned trials, but most estimates of intracluster correlation for perinatal health outcomes come from hospital-based studies and may therefore not reflect outcomes in the community. In this study we report estimates for perinatal health outcomes from community-based trials to help researchers plan future evaluations. Methods We estimated the intracluster correlation and the coefficient of variation for a range of outcomes using data from five community-based cluster randomised controlled trials in three low-income countries: India, Bangladesh and Malawi. We also performed a simulation exercise to investigate the impact of cluster size and number of clusters on the reliability of estimates of the coefficient of variation for rare outcomes. Results Estimates of intracluster correlation for mortality outcomes were lower than those for process outcomes, with narrower confidence intervals throughout for trials with larger numbers of clusters. Estimates of intracluster correlation for maternal mortality were particularly variable with large confidence intervals. Stratified randomisation had the effect of reducing estimates of intracluster correlation. The simulation exercise showed that estimates of intracluster correlation are much less reliable for rare outcomes such as maternal mortality. The size of the cluster had a greater impact than the number of clusters on the reliability of estimates for rare outcomes. Conclusions The breadth of intracluster correlation estimates reported here in terms of outcomes and contexts will help researchers plan future
Energy Technology Data Exchange (ETDEWEB)
Simson, Martin
2010-09-21
This thesis describes measurements with the retardation spectrometer aSPECT at the Institut Laue-Langevin in Grenoble. The goal of the measurement is to determine the angular correlation coefficient a from the form of the proton recoil spectrum in the decay of the free neutron in order to determine a precise value for the ratio of the weak axial vector and vector coupling constants of the nucleon. A big improvement was achieved with the use of a silicon drift detector which was used here for the first time to detect low energetic protons. A saturation effect of the electronics that was only discovered during the analysis of the data from neutron decay proved to be not correctable. The findings from analysis, simulations and test experiments gained in this work should allow a measurement of a with high precision in a future beamtime. (orig.)
Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi
2016-01-01
To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.
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İsmail Hakkı ERTEN
2008-10-01
Full Text Available This study aims to compare the appropriateness of two statistical procedures for measuring the effectiveness of vocabulary learning strategies: percentages and correlation coefficients. To do this a group of 20 learners of English were asked to study 12 words in a written list, with their pronunciations, dictionary definitions, and example sentences. Data was collected through introspection where students were asked to verbalize their mental processes as they studied the target words. A pre-test and post-test were given to measure the task achievement. The qualitative data was transcribed verbatim and content-analysed for tokens of strategy use as well as by noting whether each use of strategies led to successful recall of the words on which they were used. To calculate the strategy effectiveness, both simple percentage calculation and correlation coefficients were employed for comparison. The findings indicated that percentage calculation can give a more realistic picture of strategy effectiveness than correlation coefficients.
Indian Academy of Sciences (India)
IDA M FRIISBERG; LORENZO COSTIGLIOLA; JEPPE C DYRE
2017-07-01
This paper investigates the relation between the density-scaling exponent γ and the virial potential energy correlation coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ system in two,three, and four dimensions. The state points studied include many low-density states at which the virial potential energy correlations are not strong. For these state points we find the roughly linear relation γ∼=3n R/d in d dimensions. This result is discussed in light of the approximate “extended inverse power law” description of generalized LJ potentials (Bailey N P et al. 2008 J. Chem. Phys. 129 184508). In the plot of γ versus R there is in all cases a transition around R ≈ 0.9, above which γ starts to decrease as R approaches unity. This is consistent with the fact that γ → 2n/d for R → 1, a limit that is approached at high densities and/or high temperatures at which the repulsive r−2n term dominates the physics.
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Bahman Navidshad
2012-02-01
Full Text Available The applications of conventional culture-dependent assays to quantify bacteria populations are limited by their dependence on the inconsistent success of the different culture-steps involved. In addition, some bacteria can be pathogenic or a source of endotoxins and pose a health risk to the researchers. Bacterial quantification based on the real-time PCR method can overcome the above-mentioned problems. However, the quantification of bacteria using this approach is commonly expressed as absolute quantities even though the composition of samples (like those of digesta can vary widely; thus, the final results may be affected if the samples are not properly homogenized, especially when multiple samples are to be pooled together before DNA extraction. The objective of this study was to determine the correlation coefficients between four different methods of expressing the output data of real-time PCR-based bacterial quantification. The four methods were: (i the common absolute method expressed as the cell number of specific bacteria per gram of digesta; (ii the Livak and Schmittgen, ΔΔCt method; (iii the Pfaffl equation; and (iv a simple relative method based on the ratio of cell number of specific bacteria to the total bacterial cells. Because of the effect on total bacteria population in the results obtained using ΔCt-based methods (ΔΔCt and Pfaffl, these methods lack the acceptable consistency to be used as valid and reliable methods in real-time PCR-based bacterial quantification studies. On the other hand, because of the variable compositions of digesta samples, a simple ratio of cell number of specific bacteria to the corresponding total bacterial cells of the same sample can be a more accurate method to quantify the population.
Institute of Scientific and Technical Information of China (English)
孙银山; 张文涛; 张一茗; 于维娟; 刘逸凡
2014-01-01
智能高压开关设备在线评估技术是进行故障诊断和实施状态检修的前提和基础，采用了一种基于肯德尔相关系数计算曲线相似度的方法，以本公司自主研制开发的126kV智能隔离断路器为研究对象，在大量现场实验数据的基础上对智能隔离断路器机械状态评估进行了分析和探索。实验结果表明具有非常良好的实用性和可移植性，执行速度快，可靠性高等诸多优点，在开关设备评估中具有很好的应用前景。%Online evaluation technique for the intelligent high voltage switchgear is the premise and foundation for fault diagnosis and implementation of condition-based maintenance.With respect to the intelligent 126kV disconnecting circuit breaker developed by our company,this paper uses a method for calculating the curve similarity based on Kendall correlation coefficient to analyze and explore the evaluation of mechanical state of the intelligent discounting circuit breaker on the basis of lots of site experiment data. Experimental results indicate that this evaluation approach has excellent usability and transportability,high execution speed and high reliability,and has a good perspective of application in the evaluation of switching devices.
Collett, B; Bateman, F; Bauder, W K; Byrne, J; Byron, W A; Chen, W; Darius, G; DeAngelis, C; Dewey, M S; Gentile, T R; Hassan, M T; Jones, G L; Komives, A; Laptev, A; Mendenhall, M P; Nico, J S; Noid, G; Park, H; Stephenson, E J; Stern, I; Stockton, K J S; Trull, C; Wietfeldt, F E; Yerozolimsky, B G
2017-08-01
We describe an apparatus used to measure the electron-antineutrino angular correlation coefficient in free neutron decay. The apparatus employs a novel measurement technique in which the angular correlation is converted into a proton time-of-flight asymmetry that is counted directly, avoiding the need for proton spectroscopy. Details of the method, apparatus, detectors, data acquisition, and data reduction scheme are presented, along with a discussion of the important systematic effects.
Collett, B.; Bateman, F.; Bauder, W. K.; Byrne, J.; Byron, W. A.; Chen, W.; Darius, G.; DeAngelis, C.; Dewey, M. S.; Gentile, T. R.; Hassan, M. T.; Jones, G. L.; Komives, A.; Laptev, A.; Mendenhall, M. P.; Nico, J. S.; Noid, G.; Park, H.; Stephenson, E. J.; Stern, I.; Stockton, K. J. S.; Trull, C.; Wietfeldt, F. E.; Yerozolimsky, B. G.
2017-08-01
We describe an apparatus used to measure the electron-antineutrino angular correlation coefficient in free neutron decay. The apparatus employs a novel measurement technique in which the angular correlation is converted into a proton time-of-flight asymmetry that is counted directly, avoiding the need for proton spectroscopy. Details of the method, apparatus, detectors, data acquisition, and data reduction scheme are presented, along with a discussion of the important systematic effects.
Energy Technology Data Exchange (ETDEWEB)
Park, Sang Kyoo; Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)
2017-06-15
As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.
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Shengming Deng
2017-01-01
Full Text Available The objective of this meta-analysis is to explore the correlation between the apparent diffusion coefficient (ADC on diffusion-weighted MR and the standard uptake value (SUV of 18F-FDG on PET/CT in patients with cancer. Databases such as PubMed (MEDLINE included, EMBASE, and Cochrane Database of Systematic Review were searched for relevant original articles that explored the correlation between SUV and ADC in English. After applying Fisher’s r-to-z transformation, correlation coefficient (r values were extracted from each study and 95% confidence intervals (CIs were calculated. Sensitivity and subgroup analyses based on tumor type were performed to investigate the potential heterogeneity. Forty-nine studies were eligible for the meta-analysis, comprising 1927 patients. Pooled r for all studies was −0.35 (95% CI: −0.42–0.28 and exhibited a notable heterogeneity (I2 = 78.4%; P < 0.01. In terms of the cancer type subgroup analysis, combined correlation coefficients of ADC/SUV range from −0.12 (lymphoma, n = 5 to −0.59 (pancreatic cancer, n = 2. We concluded that there is an average negative correlation between ADC and SUV in patients with cancer. Higher correlations were found in the brain tumor, cervix carcinoma, and pancreas cancer. However, a larger, prospective study is warranted to validate these findings in different cancer types.
Pellis, E.P.M.; Franssen-Hal, van N.L.W.; Burema, J.; Keijer, J.
2003-01-01
We show that the intraclass correlation coefficient (ICC) can be used as a relatively simple statistical measure to assess methodological and biological variation in DNA microarray analysis. The ICC is a measure that determines the reproducibility of a variable, which can easily be calculated from a
Jiantian Wang
2012-01-01
This paper studies the relationship between Kendall's tau and Pearson correlation coefficient under the so-called bivariate homogeneous shock (BHS) model. We find Capéraà-Genest-type inequality may not hold for general BHS model. Computational simulations suggest that the Denials' inequality is likely to be true.
Huang, Jing; Ma, Jian-hua; Liu, Nan; Qian, Shan-shan
2010-10-01
We designed a weighted cross-correlation coefficient considering the "anchor" of the T cell epitopes, and used an evolutionary algorithm to search for an optimal weight vector. A SVM model with this new peptide similarity kernel was evaluated on a T-cell data set. The results demonstrated a good performance of this method.
1979-02-15
A simple approximate formula is shown to be remarkably accurate for the determination of the regions of the sequential test for the correlation ... coefficient , rho, when the variates follow a bivariate normal distribution. The approximate results are compared with the exact values and with an
Irrecoverable pressure loss coefficients for two out-of-plane piping elbows at high Reynolds number
Energy Technology Data Exchange (ETDEWEB)
Coffield, R.D.; Hammond, R.B.; McKeown, P.T.
1999-02-08
Pressure drops of multiple piping elbows were experimentally determined for high Reynolds number flows. The testing described has been performed in order to reduce uncertainties in the currently used methods for predicting irrecoverable pressure losses and also to provide a qualification database for computational fluid dynamics (CFD) computer codes. The earlier high Reynolds number correlations had been based on extrapolations over several orders of magnitude in Reynolds number from where the original database existed. Recent single elbow test data shows about a factor of two lower elbow pressure loss coefficient (at 40x 106 Reynolds number) than those from current correlations. This single piping elbow data has been extended in this study to a multiple elbow configuration of two elbows that are 90o out-of-plane relative to each other. The effects of separation distance and Reynolds number have been correlated and presented in a form that can be used for design application. Contrary to earlier extrapolations from low Reynolds numbers (Re c 1.0x 106), a strong Reynolds number dependence was found to exist. The combination of the high Reynolds number single elbow data with the multiple elbow interaction effects measured in this study shows that earlier design correlations are conservative by significant margins at high Reynolds numbers. Qualification of CFD predictions with this new high Reynolds number database will help guide the need for additional high Reynolds number testing of other piping configurations. The study also included velocity measurements at several positions downstream of the first and second test elbows using an ultrasonic flowmeter. Reasonable agreement after the first test elbow was found relative to flow fields that are known to exist from low Reynolds number visual tests and also from CFD predictions. This data should help to qualify CFD predictions of the three-dimensional flow stream downstream of the second test elbow.
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Sharifi Peyman
2014-01-01
Full Text Available Faba bean is a grain legume and grown for its high protein content in the seed. It is also serves as a rotational crop which play great role in controlling disease epidemics in areas were cereal mono-cropping is abundant. Yield in faba bean, similar to the other crops, is a complex trait and constitute by many of morphological and physiological traits. This study was carried out during 2011-12 and 2012-13 in two region of Iran including Guilan and Lorestan provinces. Field experiments were conducted in a randomized complete block design with three replications and ten genotypes. The results of combined analysis of variance indicated that the studied genotypes differed significantly for all of the studied traits. The results indicated also environment effect and environment × genotype interaction effects were significant or highly significant for all of the traits. The highest seed yield were determined for genotype 1 (3159.9 and 4016.9 kg ha-1 at 2012 and 2013, respectively in Guilan and genotype 5 (495.44 kg ha-1 in Lorestan. The results of correlation analysis indicated that there were positive significant correlation coefficients between seed yield and seed length (LS, seed width (WS, pod length (PL and hundred seed weight (HSW in Guilan province at two cropping season. Path coefficient analysis indicated that traits containing number of pod per plant, number of steam per plant, pod length, seed length/width ratio and hundred seed weight had the highest positive direct effects on dry seed yield in studied faba bean genotypes. Attention should be paid to some of characters such as pod length, hundred seed weight, number of pods per plant and number of stems per plant for augmentation of seed yield and these traits could be used as selection criteria in faba bean breeding programs. These findings indicate that selection for each or full of the above traits would be accompanied by high yielding ability under such conditions. It could be
Moriya, Tomohisa; Saito, Kazuhiro; Tajima, Yu; Harada, Taiyo L; Araki, Yoichi; Sugimoto, Katsutoshi; Tokuuye, Koichi
2017-01-05
To evaluate the usefulness of differentiation of histological grade in hepatocellular carcinoma (HCC) using three-dimensional (3D) analysis of apparent diffusion coefficient (ADC) histograms retrospectively. The subjects consisted of 53 patients with 56 HCCs. The subjects included 12 well-differentiated, 35 moderately differentiated, and nine poorly differentiated HCCs. Diffusion-weighted imaging (b-values of 100 and 800 s/mm(2)) were obtained within 3 months before surgery. Regions of interest (ROIs) covered the entire tumor. The data acquired from each slice were summated to derive voxel-by-voxel ADCs for the entire tumor. The following parameters were derived from the ADC histogram: mean, standard deviation, minimum, maximum, mode, percentiles (5th, 10th, 25th, 50th, 75th, and 90th), skew, and kurtosis. These parameters were analyzed according to histological grade. After eliminating steatosis lesions, these parameters were re-analyzed. A weak correlation was observed in minimum ADC and 5th percentile for each histological grade (r = -0.340 and r = -0.268, respectively). The minimum ADCs of well, moderately, and poorly differentiated HCC were 585 ± 388, 411 ± 278, and 235 ± 102 × 10(-6) mm(2)/s, respectively. Minimum ADC showed significant differences among tumor histological grades (P = 0.009). The minimum ADC of poorly differentiated HCC and that of combined well and moderately differentiated HCC were 236 ± 102 and 437 ± 299 × 10(-6) mm(2)/s. The minimum ADC of poorly differentiated HCC was significantly lower than that of combined well and moderately differentiated HCC (P = 0.001). The sensitivity and specificity, when a minimum ADC of 400 × 10(-6) mm(2)/s or lower was considered to be poorly differentiated HCC, were 100 and 54%, respectively. After exclusion of the effect of steatosis, the sensitivity and specificity did not change, although the statistical differences became strong (P < 0
Sarkar, Debdeep
2016-01-01
In this paper, the concept of cross-correlation Green's functions (CGF) is used in conjunction with the finite difference time domain (FDTD) technique for calculation of envelope correlation coefficient (ECC) of any arbitrary MIMO antenna system over wide frequency band. Both frequency-domain (FD) and time-domain (TD) post-processing techniques are proposed for possible application with this FDTD-CGF scheme. The FDTD-CGF time-domain (FDTD-CGF-TD) scheme utilizes time-domain signal processing methods and exhibits significant reduction in ECC computation time as compared to the FDTD-CGF frequency domain (FDTD-CGF-FD) scheme, for high frequency-resolution requirements. The proposed FDTD-CGF based schemes can be applied for accurate and fast prediction of wideband ECC response, instead of the conventional scattering parameter based techniques which have several limitations. Numerical examples of the proposed FDTD-CGF techniques are provided for two-element MIMO systems involving thin-wire half-wavelength dipoles ...
Directory of Open Access Journals (Sweden)
Nykolay Hristov Dyulgerov
2013-12-01
Full Text Available The aim of the present study was to generate information on interrelationships of some important productivity elements, direct and indirect effects of these characters on fruit yield of 1 plant in coriander. The study was conducted in the Institute of Agriculture - Karnobat, during the period 2006-2008 and included 81 coriander accessions. Phenotypic correlations of fruit weight per plant were highly significant and positive with number of branches per plant, number of umbels per plant, number of fruits per 1 umbel, fruit weight per umbel and 1000-fruits weight. Maximum direct contribution to fruit weight per plant was made by 1000-fruits weight, followed by fruit weight per umbel and number of umbels per plant. Therefore, these traits can be used as selection criteria to increase plant yield in coriander.
Liao, Chen-Tuo; Lin, Chia-Ying; Liu, Jen-Pei
2007-01-01
Microarray is one of the breakthrough technologies in the twenty-first century. Despite of its great potential, transition and realization of microarray technology into the clinically useful commercial products have not been as rapid as the technology could promise. One of the primary reasons is lack of agreement and poor reproducibility of the intensity measurements on gene expression obtained from microarray experiments. Current practices often use the testing the hypothesis of zero Pearson correlation coefficient to assess the agreement of gene expression levels between the technical replicates from microarray experiments. However, Pearson correlation coefficient is to evaluate linear association between two variables and fail to take into account changes in accuracy and precision. Hence, it is not appropriate for evaluation of agreement of gene expression levels between technical replicates. Therefore, we propose to use the concordance correlation coefficient to assess agreement of gene expression levels between technical replicates. We also apply the Generalized Pivotal Quantities to obtain the exact confidence interval for concordance coefficient. In addition, based on the concept of noninferiority test, a one-sided (1 - alpha) lower confidence limit for concordance correlation coefficient is employed to test the hypothesis that the agreement of expression levels of the same genes between two technical replicates exceeds some minimal requirement of agreement. We conducted a simulation study, under various combinations of mean differences, variability, and sample size, to empirically compare the performance of different methods for assessment of agreement in terms of coverage probability, expected length, size, and power. Numerical data from published papers illustrate the application of the proposed methods.
Hu, Hui; Lu, Hong; He, Zhanping; Han, Xiangjun; Chen, Jing; Tu, Rong
2012-07-25
To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25-6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.
Institute of Scientific and Technical Information of China (English)
Hui Hu; Hong Lu; Zhanping He; Xiangjun Han; Jing Chen; Rong Tu
2012-01-01
To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P < 0.01). These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time
Yang, Yan; Kang, Bo-seon
2008-11-10
The feasibility and the accuracy of the correlation coefficient (CC) method for the determination of particle positions along the optical axis in digital particle holography were verified by validation experiments. A translation system capable of high precision was used to move the particle objects by exact known distances between several different positions. The particle positions along the optical axis were calculated by the CC method and compared with their exact values to obtain the errors of the focus plane determination. The tested particles were two-dimensional (2D) dots in a calibration target along with different-sized glass beads and droplets that reflected and caused a three-dimensional (3D) effect. The results show that the CC method can work well for both the 2D dots and the 3D particles. The effect of other particles on the focus plane determination was also investigated. The CC method can locate the focus plane of particles with high precision, regardless of the existence of other particles.
Grueneisen, Johannes; Beiderwellen, Karsten; Heusch, Philipp; Buderath, Paul; Aktas, Bahriye; Gratz, Marcel; Forsting, Michael; Lauenstein, Thomas; Ruhlmann, Verena; Umutlu, Lale
2014-01-01
To evaluate a potential correlation of the maximum standard uptake value (SUVmax) and the minimum apparent diffusion coefficient (ADCmin) in primary and recurrent cervical cancer based on integrated PET/MRI examinations. 19 consecutive patients (mean age 51.6 years; range 30-72 years) with histopathologically confirmed primary cervical cancer (n = 9) or suspected tumor recurrence (n = 10) were prospectively enrolled for an integrated PET/MRI examination. Two radiologists performed a consensus reading in random order, using a dedicated post-processing software. Polygonal regions of interest (ROI) covering the entire tumor lesions were drawn into PET/MR images to assess SUVmax and into ADC parameter maps to determine ADCmin values. Pearson's correlation coefficients were calculated to assess a potential correlation between the mean values of ADCmin and SUVmax. In 15 out of 19 patients cervical cancer lesions (n = 12) or lymph node metastases (n = 42) were detected. Mean SUVmax (12.5 ± 6.5) and ADCmin (644.5 ± 179.7 × 10(-5) mm2/s) values for all assessed tumor lesions showed a significant but weak inverse correlation (R = -0.342, p correlation between SUVmax and ADCmin (R = -0.692, p correlation. These initial results of this emerging hybrid imaging technique demonstrate the high diagnostic potential of simultaneous PET/MR imaging for the assessment of functional biomarkers, revealing a significant and strong correlation of tumor metabolism and higher cellularity in cervical cancer lesions.
Yang, Yi; Wang, Tianheng; Biswal, Nrusingh C.; Wang, Xiaohong; Sanders, Melinda; Brewer, Molly; Zhu, Quing
2011-09-01
Optical scattering coefficient from ex vivo unfixed normal and malignant ovarian tissue was quantitatively extracted by fitting optical coherence tomography (OCT) A-line signals to a single scattering model. 1097 average A-line measurements at a wavelength of 1310 nm were performed at 108 sites obtained from 18 ovaries. The average scattering coefficient obtained from the normal tissue group consisted of 833 measurements from 88 sites was 2.41 mm-1 (+/-0.59), while the average coefficient obtained from the malignant tissue group consisted of 264 measurements from 20 sites was 1.55 mm-1 (+/-0.46). The malignant ovarian tissue showed significant lower scattering than the normal group (p collagen within OCT imaging depth was analyzed from the tissue histological section stained with Sirius Red. The average collagen area fraction (CAF) obtained from the normal tissue group was 48.4% (+/-12.3%), while the average CAF obtained from the malignant tissue group was 11.4% (+/-4.7%). A statistical significance of the collagen content was found between the two groups (p < 0.001). These results demonstrated that quantitative measurements of optical scattering coefficient from OCT images could be a potential powerful method for ovarian cancer detection.
DIFFUSION COEFFICIENTS IN POLYMER-SOLVENT SYSTEMS FOR HIGHLY CONCENTRATED POLYMER SOLUTIONS
Directory of Open Access Journals (Sweden)
R.A. Reis
2001-12-01
Full Text Available The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter greatly improves the performance of the model. The systems studied were poly(vinyl acetate-toluene and Neoprene-acetone, and a comparison between experimental data and calculated values from the Vrentas/Duda model is reported. A new experimental apparatus based on the sorption technique was built to provide reliable diffusivity data on the Neoprene-acetone system.
Energy Technology Data Exchange (ETDEWEB)
Kitajima, Kazuhiro, E-mail: kitajima@med.kobe-u.ac.jp [Department of Radiology, Kobe University Graduate School of Medicine, Kobe (Japan); Takahashi, Satoru; Ueno, Yoshiko [Department of Radiology, Kobe University Graduate School of Medicine, Kobe (Japan); Miyake, Hideaki; Fujisawa, Masato [Department of Urology, Kobe University Graduate School of Medicine, Kobe (Japan); Kawakami, Fumi [Division of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe (Japan); Sugimura, Kazuro [Department of Radiology, Kobe University Graduate School of Medicine, Kobe (Japan)
2013-08-15
Objective: To investigate the usefulness of apparent diffusion coefficient (ADC) values in predicting true Gleason scores from radical prostatectomy specimen (tGS), compared with systematic transrectal ultrasound (TRUS)-guided biopsy GS (bGS). Materials and methods: One hundred and five patients with biopsy-proven prostate cancer underwent preoperative DWI (b-values of 0, 1000, and 2000 s/mm{sup 2}) of 3-T MRI. The mean and minimum ADCs of visible tumors were calculated for either of a pair of b-values: 0 and 1000 s/mm{sup 2} (ADC{sub 1000}), or 0 and 2000 s/mm{sup 2} (ADC{sub 2000}), and relationships between the four ADC parameters and tGS evaluated for the peripheral zone (PZ) and transition zone (TZ). For multiple tumors, the dominant tumor's GS and ADCs were estimated for cancer aggressiveness assessment by computing ROC curves. Results: Significant negative correlations were observed between tGS and mean ADC{sub 1000}, mean ADC{sub 2000}, minimum ADC{sub 1000}, and minimum ADC{sub 2000} (r = −0.41, −0.39, −0.39, and −0.37, respectively) of 100 visible PZ tumors and 66 visible TZ tumors (r = −0.40, −0.42, −0.29, and −0.21, respectively). For distinguishing high-grade from low/intermediate-grade PZ lesions, the areas under the curve (AUCs) of mean ADC{sub 1000} (0.751), mean ADC{sub 2000} (0.710), minimum ADC{sub 1000} (0.768), and minimum ADC{sub 2000} (0.752) were similar to that of the highest bGS (0.708) (p = 0.61, p = 0.98, p = 0.47, and p = 0.60, respectively). For distinguishing high-grade from low/intermediate-grade TZ lesions, AUCs of mean ADC{sub 1000} (0.779), and mean ADC{sub 2000} (0.811) were similar to that of the highest bGS (0.805) (p = 0.83 and p = 0.97). Conclusion: Tumor ADCs obtained with high b-values could predict prostate cancer aggressiveness as effectively as systematic TRUS-guided biopsy.
Institute of Scientific and Technical Information of China (English)
李伟; 朱自强
2002-01-01
The partition coefficients of baicalin were measured in ethylene oxide and propylene oxide(EOPO)/salt aqueous two-phase systems at 298.15K,It was found that most of baicalin partitioned into EOPO-rich phase.The partition coefficients of baicalin varied from 10 to 120.The effect of various factors,including tie-line lngth,salt composition,molecular weight of EOPO,and solution pH,on the partition behavior was investigated on EOPO/salt systems.Furthermore the partition coefficients of baicalin were correlated using the modified Diamond-Hsu model.Good agreement with experimental data is obtained.The average relative deviations are less than 5.0%.
High temperature electrical resistivity and Seebeck coefficient of Ge2Sb2Te5 thin films
Adnane, L.; Dirisaglik, F.; Cywar, A.; Cil, K.; Zhu, Y.; Lam, C.; Anwar, A. F. M.; Gokirmak, A.; Silva, H.
2017-09-01
High-temperature characterization of the thermoelectric properties of chalcogenide Ge2Sb2Te5 (GST) is critical for phase change memory devices, which utilize self-heating to quickly switch between amorphous and crystalline states and experience significant thermoelectric effects. In this work, the electrical resistivity and Seebeck coefficient are measured simultaneously as a function of temperature, from room temperature to 600 °C, on 50 nm and 200 nm GST thin films deposited on silicon dioxide. Multiple heating and cooling cycles with increasingly maximum temperature allow temperature-dependent characterization of the material at each crystalline state; this is in contrast to continuous measurements which return the combined effects of the temperature dependence and changes in the material. The results show p-type conduction (S > 0), linear S(T), and a positive Thomson coefficient (dS/dT) up to melting temperature. The results also reveal an interesting linearity between dS/dT and the conduction activation energy for mixed amorphous-fcc GST, which can be used to estimate one parameter from the other. A percolation model, together with effective medium theory, is adopted to correlate the conductivity of the material with average grain sizes obtained from XRD measurements. XRD diffraction measurements show plane-dependent thermal expansion for the cubic and hexagonal phases.
Pang, Hyunsoo; Shin, Young-Han; Ihm, Dongchul; Lee, Eok Kyun; Kum, Oyeon
2000-11-01
Molecular dynamics simulations were performed for soft- and hard-sphere systems, for number densities ranging from 0.5 to 1.0, and the Kolmogorov-Sinai entropy (KS entropy) and self-diffusion coefficients were calculated. It is found that the KS entropy, when expressed in terms of average collision frequency, is uniquely related to the self-diffusion coefficient by a simple scaling law. The dependence of the KS entropy on average collision frequency and number density was also explored. Numerical results show that the scaling laws proposed by Dzugutov, and by Beijeren, Dorfman, Posch, and Dellago, can be applied to both soft- and hard-sphere systems by changing to more generalized forms.
Discharge coefficient correlations for circular-arc venturi flowmeters at critical /sonic/ flow
Arnberg, B. T.; Britton, C. L.; Seidl, W. F.
1973-01-01
Experimental data are analyzed to support theoretical predictions for discharge coefficients in circular-arc venturi flow meters operating in the critical sonic flow regime at throat Reynolds numbers above 150 thousand. The data tend to verify the predicted 0.25% decrease in the discharge coefficient during transition from a laminar to turbulent boundary layer. Four different test gases and three flow measurement facilities were used in the experiments with 17 venturis with throat sizes from 0.15 to 1.37 in. and Beta ratios ranging from 0.014 to 0.25. Recommendations are given as to how the effectiveness of future studies in the field could be improved.
Discharge coefficient correlations for circular-arc venturi flowmeters at critical /sonic/ flow
Arnberg, B. T.; Britton, C. L.; Seidl, W. F.
1973-01-01
Experimental data are analyzed to support theoretical predictions for discharge coefficients in circular-arc venturi flow meters operating in the critical sonic flow regime at throat Reynolds numbers above 150 thousand. The data tend to verify the predicted 0.25% decrease in the discharge coefficient during transition from a laminar to turbulent boundary layer. Four different test gases and three flow measurement facilities were used in the experiments with 17 venturis with throat sizes from 0.15 to 1.37 in. and Beta ratios ranging from 0.014 to 0.25. Recommendations are given as to how the effectiveness of future studies in the field could be improved.
Drabik, Dominik; Przybyło, Magda; Sikorski, Aleksander; Langner, Marek
2016-03-01
Fluorescence Correlation Spectroscopy (FCS) is a technique, which allows determination of the diffusion coefficient and concentration of fluorescent objects suspended in the solution. The measured parameter is the fluctuation of the fluorescence signal emitted by diffusing molecules. When 100 nm DOPC vesicles labeled with various fluorescent dyes (Fluorescein-PE, NBD-PE, Atto488 DOPE or βBodipy FL) were measured, different values of diffusion coefficients have been obtained. These diffusion coefficients were different from the expected values measured using the dynamic light scattering method (DLS). The FCS was initially developed for solutions containing small fluorescent molecules therefore the observed inconsistency may result from the nature of vesicle suspension itself. The duration of the fluorescence signal may depend on the following factors: the exposure time of the labeled object to the excitation beam, the photo-physical properties (e.g., stability) of a fluorophore, the theoretical model used for the calculations of the diffusion coefficient and optical properties of the vesicle suspension. The diffusion coefficients determined for differently labeled liposomes show that its dependence on vesicle size and quantity of fluorescent probed used for labeling was significant demonstrating that the fluorescence properties of the fluorophore itself (bleaching and/or blinking) were critical factors for a correct outcome of FCS experiment. The new, based on combined FCS and DLS measurements, method for the determination of the focal volume prove itself to be useful for the evaluation of a fluorescence dye with respect to its applicability for FCS experiment.
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.
DEFF Research Database (Denmark)
Ibnal Asad, Khalid; Ahmed, Tanvir; Rahman, Md. Saiedur
2012-01-01
Abundance of movie data across the internet makes it an obvious candidate for machine learning and knowledge discovery. But most researches are directed towards bi-polar classification of movie or generation of a movie recommendation system based on reviews given by viewers on various internet si...... propose classification scheme of pre-release movie popularity based on inherent attributes using C4.S and PART classifier algorithm and define the relation between attributes of post release movies using correlation coefficient....
Lipid–water partition coefficients and correlations with uptakes by algae of organic compounds
Energy Technology Data Exchange (ETDEWEB)
Hung, Wei-Nung [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 30011, Taiwan (China); Chiou, Cary T., E-mail: carychio@mail.ncku.edu.tw [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China); U.S. Geological Survey, Denver Federal Center, Denver, CO 80225 (United States); Lin, Tsair-Fuh, E-mail: tflin@mail.ncku.edu.tw [Department of Environmental Engineering and Sustainable Environment Research Laboratory, National Cheng Kung University, Tainan 70101, Taiwan (China)
2014-08-30
Graphical abstract: - Highlights: • Partition coefficients of contaminants with lipid triolein (K{sub tw}) are measured. • Measured K{sub tw} values are nearly the same as the respective K{sub ow}. • Sorption of the contaminants to a dry algal powder is similarly measured. • Algal uptake of a compound occurs primarily by partition into the algal lipid. - Abstract: In view of the scarcity of the lipid–water partition coefficients (K{sub tw}) for organic compounds, the log K{sub tw} values for many environmental contaminants were measured using ultra-pure triolein as the model lipid. Classes of compounds studied include alkyl benzenes, halogenated benzenes, short-chain chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. In addition to log K{sub tw} determination, the uptakes of these compounds from water by a dry algal species were measured to evaluate the lipid effect on the algal uptake. The measured log K{sub tw} are closely related to their respective log K{sub ow} (octanol–water), with log K{sub ow} = 1.9 to 6.5. A significant difference is observed between the present and early measured log K{sub tw} for compounds with log K{sub ow} > ∼5, which is attributed to the presence and absence of a triolein microemulsion in water affecting the solute partitioning. The observed lipid-normalized algae–water distribution coefficients (log K{sub aw/lipid}) are virtually identical to the respective log K{sub tw} values, which manifests the dominant lipid-partition effect of the compounds with algae.
Jameson, A. R.
1990-01-01
The relationship between the rainfall rate (R) obtained from radiometric brightness temperatures and the extinction coefficient (k sub e) is investigated by computing the values of k sub e over a wide range of rainfall rates, for frequencies from 3 to 25 GHz. The results show that the strength of the relation between the R and the k sub e values exhibits considerable variation for frequencies at this range. Practical suggestions are made concerning the selection of particular frequencies for rain measurements to minimize the error in R determinations.
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...
Correlation between intrinsic dipole moment and pyroelectric coefficient of Fe-Mg tourmaline
Institute of Scientific and Technical Information of China (English)
Chang-chun Zhao; Li-bing Liao; Jie Xing
2014-01-01
Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100ºC. The intrinsic dipole moments of polyhedra and the total intrinsic dipole moment of the unit cell were calculated. By comparing the intrinsic electric dipole moments of the X, Y, Z, T, and B site polyhedra, it is found that the T site polyhedron makes the greatest contribution to the total intrinsic dipole moment. The pyroelectric coefficients of four Fe-Mg tourmalines were experimentally determined, and the influence of intrinsic dipole moments on their pyroelectric properties was inves-tigated. The experimental results show that, compared with the case at room temperature, the intrinsic dipole moments change with the total Fe content at-100ºC in a completely different way. With the decrease of temperature, the total intrinsic dipole moments of tourmaline de-crease. Over the same temperature interval, the pyroelectric coefficients increase with the increase in intrinsic dipole moment.
Directory of Open Access Journals (Sweden)
Mahdi Alajmi
2015-07-01
Full Text Available The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE, Graphite/Epoxy composites (GE, and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE. The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR and coefficient of friction (COF of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs, as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.
Alajmi, Mahdi; Shalwan, Abdullah
2015-07-08
The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE), Graphite/Epoxy composites (GE), and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE). The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR) and coefficient of friction (COF) of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs), as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.
Energy Technology Data Exchange (ETDEWEB)
Oh, Ji-Won, E-mail: fromentin@naver.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Rha, Sung Eun, E-mail: serha@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Oh, Soon Nam, E-mail: hiohsn@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Park, Michael Yong, E-mail: digirave@kmle.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Byun, Jae Young, E-mail: jybyun@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Lee, Ahwon, E-mail: klee@catholic.ac.kr [Department of Hospital Pathology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of)
2015-04-15
Highlights: •The solid component of all invasive epithelial cancers showed high b{sub 1000} signal intensity. •ADCs can predict the histologic grade of epithelial ovarian cancer. •ADCs correlate negatively to the surgical stage of epithelial ovarian cancer. •ADCs may be useful imaging biomarkers to assess epithelial ovarian cancer. -- Abstract: Objective: The purpose of this article is to correlate the apparent diffusion coefficient (ADC) values of epithelial ovarian cancers with histologic grade and surgical stage. Materials and methods: We enrolled 43 patients with pathologically proven epithelial ovarian cancers for this retrospective study. All patients underwent preoperative pelvic magnetic resonance imaging (MRI) including diffusion-weighted images with b value of 0 and 1000 s/mm{sup 2} at 3.0-T unit. The mean ADC values of the solid portion of the tumor were measured and compared among different histologic grades and surgical stages. Results: The mean ADC values of epithelial ovarian cancers differed significantly between grade 1 (well-differentiated) and grade 2 (moderately-differentiated) (P = 0.013) as well as between grade 1 and grade 3 (poorly-differentiated) (P = 0.01); however, no statistically significant difference existed between grade 2 and grade 3 (P = 0.737). The receiver-operating characteristic analysis indicated that a cutoff ADC value of less than or equal to 1.09 × 10{sup −3} mm{sup 2}/s was associated with 94.4% sensitivity and 85.7% specificity in distinguishing grade 1 and grade 2/3 cancer. The difference in mean ADC values was statistically significant for early stage (FIGO stage I) and advanced stage (FIGO stage II-IV) cancer (P = 0.011). The interobserver agreement for the mean ADC values of epithelial ovarian cancers was excellent. Conclusion: The mean ADC values of the solid portion of epithelial ovarian cancers negatively correlated to histologic grade and surgical stage. The mean ADC values may be useful imaging
Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.
1994-01-01
Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.
A consistent local linear estimator of the covariate adjusted correlation coefficient.
Nguyen, Danh V; Sentürk, Damla
2009-08-01
Consider the correlation between two random variables (X, Y), both not directly observed. One only observes X̃ = φ(1)(U)X + φ(2)(U) and Ỹ = ψ(1)(U)Y + ψ(2)(U), where all four functions {φ(l)(·),ψ(l)(·), l = 1, 2} are unknown/unspecified smooth functions of an observable covariate U. We consider consistent estimation of the correlation between the unobserved variables X and Y, adjusted for the above general dual additive and multiplicative effects of U, based on the observed data (X̃, Ỹ, U).
Light vector correlator in medium: Wilson coefficients up to dimension 6 operators
Kim, HyungJoo; Gubler, Philipp; Lee, Su Houng
2017-09-01
As an improvement of the QCD sum rule method to study modifications of light vector mesons in nuclear matter and/or at finite temperature, we calculate the Wilson coefficients of all independent gluonic non-scalar operators up to dimension 6 in the operator product expansion (OPE) of the vector channel for light quarks. To obtain the gluon part of the light quark OPE from the heavy quark one, we also compute the heavy quark expansion of the relevant quark condensates. Together with the results for the quark operators that are already available in the literature, this completes the OPE of the vector channel in a hot or dense medium for operators up to dimension 6.
Directory of Open Access Journals (Sweden)
Navid Ghaffarzadeh
2013-03-01
Full Text Available In this paper a novel method based on discrete wavelet transform and correlation coefficient is presented for distinguishing between arcing and permanent faults. The algorithm includes offline and online processing. In the offline, discrete wavelet transform is used to decompose typical faulted phase voltage waveforms during arcing faults. An index is then defined and computed. The index is based on the normalised energy of detail coefficients at resolution levels 1 to 14. The online processing consists of capturing the faulted phase voltage waveform using a 20 kHz sampling rate, and decomposing it by db4. Finally, arcing faults are distinguished from permanent faults based on correlation coefficient of the computed index of the pre-stored typical arcing faults and a recorded indistinct signal. The effectiveness of the approach has been tested for numerous arcing and permanent fault conditions on a transmission line using the Electromagnetic transient Program (EMTP software tool. The simulation results show the capability of the proposed method in distinguishing between arcing faults from permanent faults.
Hedge, Sh; Klimova, E Iu; Mande, Sh; Medvedeva, Iu A; Makeev, V Iu; Permina, E A
2011-01-01
We developed an approach for effective estimating the correlations in the noise component of gene expression data. An efficent noise reduction technique has been suggested. The resulting technique has been applied to E. coli microarray data and tested on SOS response modulated genes.
Barchard, Kimberly A.
2012-01-01
This article introduces new statistics for evaluating score consistency. Psychologists usually use correlations to measure the degree of linear relationship between 2 sets of scores, ignoring differences in means and standard deviations. In medicine, biology, chemistry, and physics, a more stringent criterion is often used: the extent to which…
On the construction of bivariate exponential distributions with an arbitrary correlation coefficient
DEFF Research Database (Denmark)
Bladt, Mogens; Nielsen, Bo Friis
In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....
On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient
DEFF Research Database (Denmark)
Bladt, Mogens; Nielsen, Bo Friis
2010-01-01
In this article we use the concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....
Proposal for a Correction to the Temporal Correlation Coefficient Calculation for Temporal Networks
Pigott, Fiona
2014-01-01
Measuring the topological overlap of two graphs becomes important when assessing the changes between temporally adjacent graphs in a time-evolving network. Current methods depend on the fraction of nodes that have persisting edges. This breaks down when there are nodes with no edges, persisting or otherwise. The following outlines a proposed correction to ensure that correlation metrics have the expected behavior.
Korcyl, Piotr
2016-01-01
We determine quark mass dependent order $a$ improvement terms of the form $b_J am$ for non-singlet scalar, pseudoscalar, vector and axialvector currents, using correlators in coordinate space. We use a set of CLS ensembles comprising non-perturbatively improved Wilson Fermions and the tree-level Luescher-Weisz gauge action at $\\beta=3.4,3.46,3.55$ and $\\beta=3.7$, corresponding to lattice spacings $a$ ranging from $0.05$ fm to $0.09$ fm. We report the values of the $b_J$ improvement coefficients which are proportional to non-singlet quark mass combinations and also discuss the possibility of determining the $\\bar{b}_J$ coefficients which are proportional to the trace of the quark mass matrix.
Lu, Fengbin; Qiao, Han; Wang, Shouyang; Lai, Kin Keung; Li, Yuze
2017-01-01
This paper proposes a new time-varying coefficient vector autoregressions (VAR) model, in which the coefficient is a linear function of dynamic lagged correlation. The proposed model allows for flexibility in choices of dynamic correlation models (e.g. dynamic conditional correlation generalized autoregressive conditional heteroskedasticity (GARCH) models, Markov-switching GARCH models and multivariate stochastic volatility models), which indicates that it can describe many types of time-varying causal effects. Time-varying causal relations between West Texas Intermediate (WTI) crude oil and the US Standard and Poor's 500 (S&P 500) stock markets are examined by the proposed model. The empirical results show that their causal relations evolve with time and display complex characters. Both positive and negative causal effects of the WTI on the S&P 500 in the subperiods have been found and confirmed by the traditional VAR models. Similar results have been obtained in the causal effects of S&P 500 on WTI. In addition, the proposed model outperforms the traditional VAR model. Copyright Â© 2016 Elsevier Ltd. All rights reserved.
Robin, M. J. L.; Sudicky, E. A.; Gillham, R. W.; Kachanoski, R. G.
1991-10-01
Distribution coefficients (Kd), defined as the ratio of the concentration of solute associated with the solids to the concentration in solution, are widely used in the prediction of reactive solute transport. With the advent of stochastic approaches to describe solute transport, there is a need to examine the spatial distribution of Kd, and its correlation with the hydraulic conductivity (K). Distribution coefficients were measured in triplicates for strontium on 1279 subsamples of cores from Canadian Forces Base Borden for which K measurements were available. The Kd values ranged from 4.4 to 29.8 mL/g, with a mean of 9.9 and standard deviation of 2.89 mL/g. The standard error on the triplicate means was 0.95 mL/g or approximately 10% of the mean. The spatial behavior of Kd and K (expressed as In (Kd) and ln (K)) was examined in three directions: horizontally along two orthogonal transects and vertically. The two variables each behaved nearly identically in the two horizontal directions, suggesting horizontal isotropy. Horizontally, ln (Kd) appeared as "white noise" suggesting that the horizontal spacing between cores (1 m) was too large to detect any self-correlation. The distribution coefficient displayed increasing power spectral density with increasing scale in the vertical direction, while In (K) showed these trends in all directions. Depending on the model used, the, correlation lengths obtained by least squares fits of the power spectra varied from 1 to 7.5 m horizontally and from 10 to 30 cm vertically for ln (K); and from 30 cm to 2 m horizontally and from 30 to 70 cm vertically for ln (Kd). The ln (Kd) values showed a significant but very weak negative overall correlation with ln (K) at the 99.95% confidence level. The cross-spectral and coherency analysis showed that the sign and degree of correlation between ln (Kd) and ln (K) depended on the scale and direction considered. The correlations in all directions and at all scales were weak, and could not
Rocco, Paolo; Cilurzo, Francesco; Minghetti, Paola; Vistoli, Giulio; Pedretti, Alessandro
2017-10-01
The data presented in this article are related to the article titled "Molecular Dynamics as a tool for in silico screening of skin permeability" (Rocco et al., 2017) [1]. Knowledge of the confidence interval and maximum theoretical value of the correlation coefficient r can prove useful to estimate the reliability of developed predictive models, in particular when there is great variability in compiled experimental datasets. In this Data in Brief article, data from purposely designed numerical simulations are presented to show how much the maximum r value is worsened by increasing the data uncertainty. The corresponding confidence interval of r is determined by using the Fisher r→Z transform.
Lin, Yuning; Li, Hui; Chen, Ziqian; Ni, Ping; Zhong, Qun; Huang, Huijuan; Sandrasegaran, Kumar
2015-05-01
The purpose of this study was to investigate the application of histogram analysis of apparent diffusion coefficient (ADC) in characterizing pathologic features of cervical cancer and benign cervical lesions. This prospective study was approved by the institutional review board, and written informed consent was obtained. Seventy-three patients with cervical cancer (33-69 years old; 35 patients with International Federation of Gynecology and Obstetrics stage IB cervical cancer) and 38 patients (38-61 years old) with normal cervix or cervical benign lesions (control group) were enrolled. All patients underwent 3-T diffusion-weighted imaging (DWI) with b values of 0 and 800 s/mm(2). ADC values of the entire tumor in the patient group and the whole cervix volume in the control group were assessed. Mean ADC, median ADC, 25th and 75th percentiles of ADC, skewness, and kurtosis were calculated. Histogram parameters were compared between different pathologic features, as well as between stage IB cervical cancer and control groups. Mean ADC, median ADC, and 25th percentile of ADC were significantly higher for adenocarcinoma (p = 0.021, 0.006, and 0.004, respectively), and skewness was significantly higher for squamous cell carcinoma (p = 0.011). Median ADC was statistically significantly higher for well or moderately differentiated tumors (p = 0.044), and skewness was statistically significantly higher for poorly differentiated tumors (p = 0.004). No statistically significant difference of ADC histogram was observed between lymphovascular space invasion subgroups. All histogram parameters differed significantly between stage IB cervical cancer and control groups (p < 0.05). Distribution of ADCs characterized by histogram analysis may help to distinguish early-stage cervical cancer from normal cervix or cervical benign lesions and may be useful for evaluating the different pathologic features of cervical cancer.
Kawai, K; Noguchi, H
2002-01-01
Effective dose coefficients, the committed effective dose per unit intake, by inhalation and ingestion have been calculated for 304 nuclides, including (1) 230 nuclides with half-lives >= 10 min and their daughters that are not listed in ICRP Publications and (2) 74 nuclides with half-lives < 10 min that are produced in a spallation target. Effective dose coefficients for inhalation of soluble or reactive gases have been calculated for 21 nuclides, and effective dose rates for inert gases have been calculated for 9 nuclides. Dose calculation was carried out using a general-purpose nuclear decay database DECDC developed at JAERI and a decay data library newly compiled from the ENSDF for the nuclides abundantly produced in a spallation target. The dose coefficients were calculated with the computer code DOCAP based on the respiratory tract model and biokinetic model of ICRP. The effective dose rates were calculated by considering both external irradiation from the surrounding cloud and irradiation of the lun...
Directory of Open Access Journals (Sweden)
Marcin Kozak
2012-12-01
Full Text Available This paper discusses a number of aspects concerning the analysis, interpretation and reporting of correlations in agricultural sciences. Various problems that one might encounter with these aspects are identified, and suggestions of how to overcome these problems are proposed. Some of the examples presented show how mistaken and even misleading the interpretation of correlation can be when one ignores simple rules of analysis.Este artigo discute uma série de aspectos relacionados a análise, interpretação e forma de relatar correlações em ciências Agrárias. São identificados vários problemas que podem ser encontrados, bem como feitas sugestões de como superá-los. Alguns dos exemplos apresentados mostram quão erradas e mesmo enganosas podem ser as interpretações de correlação quando regras simples de análise são ignoradas.
Shen, Guohua; Ma, Huan; Liu, Bin; Ren, Pengwei; Kuang, Anren
2017-09-06
Diffusion-weighted imaging and fluorine-18-fluorodeoxyglucose PET are increasingly being recognized as feasible oncological techniques. The apparent diffusion coefficient (ADC) measured by diffusion-weighted imaging and the standardized uptake value (SUV) from fluorine-18-fluorodeoxyglucose PET have similar clinical applications. The aim of this study was to assess the correlation between these two parameters in various cancers. Several major databases were searched for eligible studies. The correlation coefficient (ρ) values were pooled in a random-effects model. Begg's test was used to analyze the existence of publication bias and the sources of heterogeneity were explored in subgroup analyses on the basis of study design, diagnostic method, scanning modality, and tumor type. Thirty-five articles were accepted. The pooled ρ value of all of the accepted studies was -0.30 (95% confidence interval: -0.33 to -0.27), and notable heterogeneity was present (I=69.4%, Pcorrelation. The pooled ρ values were -0.26, -0.33, -0.32, and -0.33 for the SUVmax/ADCmean, SUVmax/ADCmin, SUVmean/ADCmean, and SUVmean/ADCmin relationships, respectively. The study design and diagnostic method were potential sources of heterogeneity. Lung cancer showed a stronger correlation (ρ=-0.42) than head and neck cancer (ρ=-0.27), cervical cancer (ρ=-0.21), and breast cancer (ρ=-0.23). A Begg's test indicated no significant publication bias among the accepted studies (P>0.05). The two functional parameters of ADC and SUV showed a very weak inverse correlation, which may contribute toward a sophisticated characterization of tumor biology. However, the findings require further validation with trials with large samples and different tumor types.
Directory of Open Access Journals (Sweden)
C. N. Warwick
2015-09-01
Full Text Available We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT and 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT. The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.
Schüürmann, Gerrit; Ebert, Ralf-Uwe; Chen, Jingwen; Wang, Bin; Kühne, Ralph
2008-11-01
The external prediction capability of quantitative structure-activity relationship (QSAR) models is often quantified using the predictive squared correlation coefficient, q (2). This index relates the predictive residual sum of squares, PRESS, to the activity sum of squares, SS, without postprocessing of the model output, the latter of which is automatically done when calculating the conventional squared correlation coefficient, r (2). According to the current OECD guidelines, q (2) for external validation should be calculated with SS referring to the training set activity mean. Our present findings including a mathematical proof demonstrate that this approach yields a systematic overestimation of the prediction capability that is triggered by the difference between the training and test set activity means. Example calculations with three regression models and data sets taken from literature show further that for external test sets, q (2) based on the training set activity mean may become even larger than r (2). As a consequence, we suggest to always use the test set activity mean when quantifying the external prediction capability through q (2) and to revise the respective OECD guidance document accordingly. The discussion includes a comparison between r (2) and q (2) value ranges and the q (2) statistics for cross-validation.
Directory of Open Access Journals (Sweden)
Daniel Paech
Full Text Available To explore the correlation between Nuclear Overhauser Enhancement (NOE-mediated signals and tumor cellularity in glioblastoma utilizing the apparent diffusion coefficient (ADC and cell density from histologic specimens. NOE is one type of chemical exchange saturation transfer (CEST that originates from mobile macromolecules such as proteins and might be associated with tumor cellularity via altered protein synthesis in proliferating cells.For 15 patients with newly diagnosed glioblastoma, NOE-mediated CEST-contrast was acquired at 7 Tesla (asymmetric magnetization transfer ratio (MTRasym at 3.3ppm, B1 = 0.7 μT. Contrast enhanced T1 (CE-T1, T2 and diffusion-weighted MRI (DWI were acquired at 3 Tesla and coregistered. The T2 edema and the CE-T1 tumor were segmented. ADC and MTRasym values within both regions of interest were correlated voxelwise yielding the correlation coefficient rSpearman (rSp. In three patients who underwent stereotactic biopsy, cell density of 12 specimens per patient was correlated with corresponding MTRasym and ADC values of the biopsy site.Eight of 15 patients showed a weak or moderate positive correlation of MTRasym and ADC within the T2 edema (0.16≤rSp≤0.53, p0.05, n = 4 or yielded rSp≈0 (p0.05, n = 6. The biopsy-analysis within CE-T1 tumor revealed a strong positive correlation between tumor cellularity and MTRasym values in two of the three patients (rSppatient3 = 0.69 and rSppatient15 = 0.87, p<0.05, while the correlation of ADC and cellularity was heterogeneous (rSppatient3 = 0.545 (p = 0.067, rSppatient4 = -0.021 (p = 0.948, rSppatient15 = -0.755 (p = 0.005.NOE-imaging is a new contrast promising insight into pathophysiologic processes in glioblastoma regarding cell density and protein content, setting itself apart from DWI. Future studies might be based on the assumption that NOE-mediated CEST visualizes cellularity more accurately than ADC, especially in the CE-T1 tumor region.
Duan, Yabo; Song, Chengtian
2016-10-01
Empirical mode decomposition (EMD) is a recently proposed nonlinear and nonstationary laser signal denoising method. A noisy signal is broken down using EMD into oscillatory components that are called intrinsic mode functions (IMFs). Thresholding-based denoising and correlation-based partial reconstruction of IMFs are the two main research directions for EMD-based denoising. Similar to other decomposition-based denoising approaches, EMD-based denoising methods require a reliable threshold to determine which IMFs are noise components and which IMFs are noise-free components. In this work, we propose a new approach in which each IMF is first denoised using EMD interval thresholding (EMD-IT), and then a robust thresholding process based on Spearman correlation coefficient is used for relevant modes selection. The proposed method tackles the problem using a thresholding-based denoising approach coupled with partial reconstruction of the relevant IMFs. Other traditional denoising methods, including correlation-based EMD partial reconstruction (EMD-Correlation), discrete Fourier transform and wavelet-based methods, are investigated to provide a comparison with the proposed technique. Simulation and test results demonstrate the superior performance of the proposed method when compared with the other methods.
Duan, Yabo; Song, Chengtian
2016-12-01
Empirical mode decomposition (EMD) is a recently proposed nonlinear and nonstationary laser signal denoising method. A noisy signal is broken down using EMD into oscillatory components that are called intrinsic mode functions (IMFs). Thresholding-based denoising and correlation-based partial reconstruction of IMFs are the two main research directions for EMD-based denoising. Similar to other decomposition-based denoising approaches, EMD-based denoising methods require a reliable threshold to determine which IMFs are noise components and which IMFs are noise-free components. In this work, we propose a new approach in which each IMF is first denoised using EMD interval thresholding (EMD-IT), and then a robust thresholding process based on Spearman correlation coefficient is used for relevant modes selection. The proposed method tackles the problem using a thresholding-based denoising approach coupled with partial reconstruction of the relevant IMFs. Other traditional denoising methods, including correlation-based EMD partial reconstruction (EMD-Correlation), discrete Fourier transform and wavelet-based methods, are investigated to provide a comparison with the proposed technique. Simulation and test results demonstrate the superior performance of the proposed method when compared with the other methods.
Dose conversion coefficients for high-energy photons, electrons, neutrons and protons
Sakamoto, Y; Sato, O; Tanaka, S I; Tsuda, S; Yamaguchi, Y; Yoshizawa, N
2003-01-01
In the International Commission on Radiological Protection (ICRP) 1990 Recommendations, radiation weighting factors were introduced in the place of quality factors, the tissue weighting factors were revised, and effective doses and equivalent doses of each tissues and organs were defined as the protection quantities. Dose conversion coefficients for photons, electrons and neutrons based on new ICRP recommendations were cited in the ICRP Publication 74, but the energy ranges of theses data were limited and there are no data for high energy radiations produced in accelerator facilities. For the purpose of designing the high intensity proton accelerator facilities at JAERI, the dose evaluation code system of high energy radiations based on the HERMES code was developed and the dose conversion coefficients of effective dose were evaluated for photons, neutrons and protons up to 10 GeV, and electrons up to 100 GeV. The dose conversion coefficients of effective dose equivalent were also evaluated using quality fact...
Paech, Daniel; Burth, Sina; Windschuh, Johannes; Meissner, Jan-Eric; Zaiss, Moritz; Eidel, Oliver; Kickingereder, Philipp; Nowosielski, Martha; Wiestler, Benedikt; Sahm, Felix; Floca, Ralf Omar; Neumann, Jan-Oliver; Wick, Wolfgang; Heiland, Sabine; Bendszus, Martin; Schlemmer, Heinz-Peter; Ladd, Mark Edward; Bachert, Peter; Radbruch, Alexander
2015-01-01
To explore the correlation between Nuclear Overhauser Enhancement (NOE)-mediated signals and tumor cellularity in glioblastoma utilizing the apparent diffusion coefficient (ADC) and cell density from histologic specimens. NOE is one type of chemical exchange saturation transfer (CEST) that originates from mobile macromolecules such as proteins and might be associated with tumor cellularity via altered protein synthesis in proliferating cells. For 15 patients with newly diagnosed glioblastoma, NOE-mediated CEST-contrast was acquired at 7 Tesla (asymmetric magnetization transfer ratio (MTRasym) at 3.3ppm, B1 = 0.7 μT). Contrast enhanced T1 (CE-T1), T2 and diffusion-weighted MRI (DWI) were acquired at 3 Tesla and coregistered. The T2 edema and the CE-T1 tumor were segmented. ADC and MTRasym values within both regions of interest were correlated voxelwise yielding the correlation coefficient rSpearman (rSp). In three patients who underwent stereotactic biopsy, cell density of 12 specimens per patient was correlated with corresponding MTRasym and ADC values of the biopsy site. Eight of 15 patients showed a weak or moderate positive correlation of MTRasym and ADC within the T2 edema (0.16≤rSp≤0.53, pcorrelations were statistically insignificant (p>0.05, n = 4) or yielded rSp≈0 (pcorrelation between MTRasym and ADC was found in CE-T1 tumor (-0.310.05, n = 6). The biopsy-analysis within CE-T1 tumor revealed a strong positive correlation between tumor cellularity and MTRasym values in two of the three patients (rSppatient3 = 0.69 and rSppatient15 = 0.87, pcorrelation of ADC and cellularity was heterogeneous (rSppatient3 = 0.545 (p = 0.067), rSppatient4 = -0.021 (p = 0.948), rSppatient15 = -0.755 (p = 0.005)). NOE-imaging is a new contrast promising insight into pathophysiologic processes in glioblastoma regarding cell density and protein content, setting itself apart from DWI. Future studies might be based on the assumption that NOE-mediated CEST visualizes
Directory of Open Access Journals (Sweden)
Peter A. Ajibade
2011-06-01
Full Text Available In our quest to develop good materials as photosensitizers for photovoltaic dye-sensitized solar cells (DSSCs, cis-dithiocyanato-4-(2,3-dimethylacrylic acid-2,2'-bipyridyl-4-(9-anthracenyl-(2,3-dimethylacrylic-2,2'-bipyridyl ruthenium(II complex, a high molar extinction coefficient charge transfer sensitizer, was designed, synthesized and characterized by spectroscopy and electrochemical techniques. Earlier studies on heteroleptic ruthenium(II complex analogues containing functionalized oligo-anthracenyl phenanthroline ligands have been reported and documented. Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, herein, we report the photophysical and electrochemical properties of a Ru(II bipyridyl complex analogue with a single functionalized anthracenyl unit. Interestingly, the complex shows better broad and intense metal-to ligand charge transfer (MLCT band absorption with higher molar extinction coefficient (λmax = 518 nm, e = 44900 M−1cm−1, and appreciable photoluminescence spanning the visible region than those containing higher anthracenyl units. It was shown that molar absorption coefficient of the complexes may not be solely depended on the extended π-conjugation but are reduced by molecular aggregation in the molecules.
Nadeem, Qurrat-Ul-Ain
2015-05-07
Previous studies have confirmed the adverse impact of fading correlation on the mutual information (MI) of two-dimensional (2D) multiple-input multiple-output (MIMO) systems. More recently, the trend is to enhance the system performance by exploiting the channel’s degrees of freedom in the elevation, which necessitates the derivation and characterization of three-dimensional (3D) channels in the presence of spatial correlation. In this paper, an exact closed-form expression for the Spatial Correlation Function (SCF) is derived for 3D MIMO channels. This novel SCF is developed for a uniform linear array of antennas with nonisotropic antenna patterns. The proposed method resorts to the spherical harmonic expansion (SHE) of plane waves and the trigonometric expansion of Legendre and associated Legendre polynomials. The resulting expression depends on the underlying arbitrary angular distributions and antenna patterns through the Fourier Series (FS) coefficients of power azimuth and elevation spectrums. The novelty of the proposed method lies in the SCF being valid for any 3D propagation environment. The developed SCF determines the covariance matrices at the transmitter and the receiver that form the Kronecker channel model. In order to quantify the effects of correlation on the system performance, the information-theoretic deterministic equivalents of the MI for the Kronecker model are utilized in both mono-user and multi-user cases. Numerical results validate the proposed analytical expressions and elucidate the dependence of the system performance on azimuth and elevation angular spreads and antenna patterns. Some useful insights into the behaviour of MI as a function of downtilt angles are provided. The derived model will help evaluate the performance of correlated 3D MIMO channels in the future.
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Liu, Song, E-mail: songliu532909756@gmail.com [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Guan, Wenxian, E-mail: wenxianguan123@126.com [Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Wang, Hao, E-mail: wanghao20140525@126.com [Department of Gastrointestinal Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Pan, Liang, E-mail: panliang2014@126.com [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Zhou, Zhuping, E-mail: zhupingzhou@126.com [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Yu, Haiping, E-mail: haipingyu2012@126.com [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Liu, Tian, E-mail: tianliu2014@126.com [Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322 (United States); Yang, Xiaofeng, E-mail: xiaofengyang2014@126.com [Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA 30322 (United States); He, Jian, E-mail: hjxueren@126.com [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China); Zhou, Zhengyang, E-mail: zyzhou@nju.edu.cn [Department of Radiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008 (China)
2014-12-15
Highlights: • Gastric cancers’ ADC values were significantly lower than normal gastric wall. • Gastric adenocarcinomas with different differentiation had different ADC values. • Gastric adenocarcinomas’ ADC values correlated with histologic differentiations. • Gastric cancers’ ADC values correlated with Lauren classifications. • Mean ADC value was better than min ADC value in characterizing gastric cancers. - Abstract: Objective: The purpose of this study was to evaluate the correlations between histological differentiation and Lauren classification of gastric cancer and the apparent diffusion coefficient (ADC) value of diffusion weighted imaging (DWI). Materials and methods: Sixty-nine patients with gastric cancer lesions underwent preoperative magnetic resonance imaging (MRI) (3.0T) and surgical resection. DWI was obtained with a single-shot, echo-planar imaging sequence in the axial plane (b values: 0 and 1000 s/mm{sup 2}). Mean and minimum ADC values were obtained for each gastric cancer and normal gastric walls by two radiologists, who were blinded to the histological findings. Histological type, degree of differentiation and Lauren classification of each resected specimen were determined by one pathologist. Mean and minimum ADC values of gastric cancers with different histological types, degrees of differentiation and Lauren classifications were compared. Correlations between ADC values and histological differentiation and Lauren classification were analyzed. Results: The mean and minimum ADC values of gastric cancers, as a whole and separately, were significantly lower than those of normal gastric walls (all p values <0.001). There were significant differences in the mean and minimum ADC values among gastric cancers with different histological types, degrees of differentiation and Lauren classifications (p < 0.05). Mean and minimum ADC values correlated significantly (all p < 0.001) with histological differentiation (r = 0.564, 0.578) and
Rosner, Bernard; Glynn, Robert J
2007-02-10
The Spearman (rho(s)) and Kendall (tau) rank correlation coefficient are routinely used as measures of association between non-normally distributed random variables. However, confidence limits for rho(s) are only available under the assumption of bivariate normality and for tau under the assumption of asymptotic normality of tau. In this paper, we introduce another approach for obtaining confidence limits for rho(s) or tau based on the arcsin transformation of sample probit score correlations. This approach is shown to be applicable for an arbitrary bivariate distribution. The arcsin-based estimators for rho(s) and tau (denoted by rho(s,a), tau(a)) are shown to have asymptotic relative efficiency (ARE) of 9/pi2 compared with the usual estimators rho(s) and tau when rho(s) and tau are, respectively, 0. In some nutritional applications, the Spearman rank correlation between nutrient intake as assessed by a reference instrument versus nutrient intake as assessed by a surrogate instrument is used as a measure of validity of the surrogate instrument. However, if only a single replicate (or a few replicates) are available for the reference instrument, then the estimated Spearman rank correlation will be downwardly biased due to measurement error. In this paper, we use the probit transformation as a tool for specifying an ANOVA-type model for replicate ranked data resulting in a point and interval estimate of a measurement error corrected rank correlation. This extends previous work by Rosner and Willett for obtaining point and interval estimates of measurement error corrected Pearson correlations.
Zheng, Ping; He, Bin; Guo, Yijun; Zeng, Jingsong; Tong, Wusong
2015-07-01
The relationship between microstructural abnormality in patients with traumatic brain injury (TBI) and hormone-secreting status remains unknown. In this study, the authors aimed to identify the role of the apparent diffusion coefficient (ADC) using a diffusion-weighted imaging (DWI) technique and to evaluate the association of such changes with hypopituitarism in patients with TBI. Diffusion-weighted images were obtained in 164 consecutive patients with TBI within 2 weeks after injury to generate the pituitary ADC as a measure of microstructural change. Patients with TBI were further grouped into those with and those without hypopituitarism based on the secretion status of pituitary hormones at 6 months postinjury. Thirty healthy individuals were enrolled in the study and underwent MRI examinations for comparison. Mean ADC values were compared between this control group, the patients with TBI and hypopituitarism, and the patients with TBI without hypopituitarism; correlational studies were also performed. Neurological outcome was assessed with the Glasgow Outcome Scale (GOS) for all TBI patients 6 months postinjury. In the TBI group, 84 patients had hypopituitarism and 80 had normal pituitary function. The pituitary ADC in TBI patients was significantly less than that in controls (1.83 ± 0.16 vs 4.13 ± 0.33, p correlated with neurological outcome at 6 months following TBI (r = 0.602, p correlated with hormone-secreting status in TBI patients. The authors suggest that pituitary ADC may be a useful biomarker to predict pituitary function in patients with TBI.
Wu, X; Reinikainen, P; Vanhanen, A; Kapanen, M; Vierikko, T; Ryymin, P; Hyödynmaa, S; Kellokumpu-Lehtinen, P-L
2017-01-01
To investigate whether diffusion-weighted imaging (DWI) apparent diffusion coefficient (ADC) correlates with prostate cancer aggressiveness and further to compare the diagnostic performance of ADC and normalized ADC (nADC: normalized to non-tumor tissue). Thirty pre-treatment patients (mean age, 69years; range: 59-78years) with prostate cancer underwent magnetic resonance imaging (MRI) examination, including DWI with three b values: 50, 400, and 800s/mm(2). Both ADC and nADC were correlated with the Gleason score obtained through transrectal ultrasound-guided biopsy. The tumor minimum ADC (ADCmin: the lowest ADC value within tumor) had an inverse correlation with the Gleason score (r=-0.43, Pcorrelated with the Gleason score (r=-0.52 and r=-0.55, P<0.01; respectively), and they were lower in patients with Gleason score 3+4 than those with Gleason score 3+3 (P<0.01; respectively). Receiver operating characteristic (ROC) analysis showed that the area under the ROC curve was 0.765, 0.818, or 0.833 for the ADCmin, nADCmin, or nADCmean; respectively, in differentiating between Gleason score 3+4 and 3+3 tumors. Tumor ADCmin, nADCmin, and nADCmean are useful markers to predict the aggressiveness of prostate cancer. Copyright © 2016 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.
Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu
2016-07-15
The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values.
Estimation of Coefficient of Pressure in High Rise Buildings Using Artificial Neural Network
Directory of Open Access Journals (Sweden)
S. K. Verma
2014-04-01
Full Text Available Tendency to build more slender and more flexible tall buildings have made these structures susceptible to action of wind. Therefore, wind force is one of the prime considerations in design of tall buildings. The prediction of wind-induced pressure coefficients on the surface of the buildings is of considerable practical importance. Wind tunnel testing is one of the main methods for wind load determination on structures. But this being, time consuming and costly wind tunnel tests can only cover a limited number of cases. The present work focuses on the application of artificial neural networks (ANNs to estimate pressure coefficients on surface of tall buildings. In the present study, two cases of training data set (consisting of geometrical coordinates of pressure points and angle at which wind strikes at the face of the building as the input to the network has been used to predict the wind- induced `pressure coefficients Cp (mean (output of the network for the previously any wind incident angle. The performance of the network is assessed in terms of Root Mean Square Error (RMSE and Correlation Coefficient R. From the present study, it is concluded that the value of Cp (Mean goes on decreasing with increase in Wind Incidence Angle for the same pressure point. Also, suction effect is noticed near the corners of the building.
Korcyl, Piotr
2016-01-01
We determine quark mass dependent order $a$ improvement terms of the form $b_Jam$ for non-singlet scalar, pseudoscalar, vector and axialvector currents using correlators in coordinate space on a set of CLS ensembles. These have been generated employing non-perturbatively improved Wilson Fermions and the tree-level L\\"uscher-Weisz gauge action at $\\beta = 3.4, 3.46, 3.55$ and $3.7$, corresponding to lattice spacings ranging from $a \\approx 0.085$ fm down to $0.05$ fm. In the $N_f=2+1$ flavour theory two types of improvement coefficients exist: $b_J$, proportional to non-singlet quark mass combinations, and $\\bar{b}_J$ (or $\\tilde{b}_J$), proportional to the trace of the quark mass matrix. Combining our non-perturbative determinations with perturbative results, we quote Pad\\'e approximants parameterizing the $b_J$ improvement coefficients within the above window of lattice spacings. We also give preliminary results for $\\tilde{b}_J$ at $\\beta=3.4$.
Kelley, Ken
2008-01-01
Methods of sample size planning are developed from the accuracy in parameter approach in the multiple regression context in order to obtain a sufficiently narrow confidence interval for the population squared multiple correlation coefficient when regressors are random. Approximate and exact methods are developed that provide necessary sample size so that the expected width of the confidence interval will be sufficiently narrow. Modifications of these methods are then developed so that necessary sample size will lead to sufficiently narrow confidence intervals with no less than some desired degree of assurance. Computer routines have been developed and are included within the MBESS R package so that the methods discussed in the article can be implemented. The methods and computer routines are demonstrated using an empirical example linking innovation in the health services industry with previous innovation, personality factors, and group climate characteristics.
Carrasco, Josep L
2010-09-01
The classical concordance correlation coefficient (CCC) to measure agreement among a set of observers assumes data to be distributed as normal and a linear relationship between the mean and the subject and observer effects. Here, the CCC is generalized to afford any distribution from the exponential family by means of the generalized linear mixed models (GLMMs) theory and applied to the case of overdispersed count data. An example of CD34+ cell count data is provided to show the applicability of the procedure. In the latter case, different CCCs are defined and applied to the data by changing the GLMM that fits the data. A simulation study is carried out to explore the behavior of the procedure with a small and moderate sample size.
Directory of Open Access Journals (Sweden)
Reza Azad
2013-11-01
Full Text Available Hand gesture recognition possesses extensive applications in virtual reality, sign language recognition, and computer games. The direct interface of hand gestures provides us a new way for communicating with the virtual environment. In this paper a novel and real-time approach for hand gesture recognition system is presented. In the suggested method, first, the hand gesture is extracted from the main image by the image segmentation and morphological operation and then is sent to feature extraction stage. In feature extraction stage the Cross-correlation coefficient is applied on the gesture to recognize it. In the result part, the proposed approach is applied on American Sign Language (ASL database and the accuracy rate obtained 98.34%.
Institute of Scientific and Technical Information of China (English)
Li-qun Cao; De-chao Zhu; Jian-Lan Luo
2002-01-01
In this paper, we will discuss the asymptotic behaviour for a class of hyper bolic -parabolic type equation with highly oscillatory coefficients arising from the strong-transient heat and mass transfer problems of composite media. A complete multiscale asymptotic expansion and its rigorous verification will be reported.
Thermographic determination of the sheath heat transmission coefficient in a high density plasma
van den Berg, M. A.; Bystrov, K.; Pasquet, R.; Zielinski, J. J.; De Temmerman, G.
2013-01-01
Experiments were performed in the Pilot-PSI linear plasma device, to determine the sheath heat transmission coefficients in a high recycling regime under various conditions of density (1–20 × 1020 m−3) and plasma composition (H2, Ar, N2) relevant for the
Thermographic determination of the sheath heat transmission coefficient in a high density plasma
van den Berg, M. A.; Bystrov, K.; Pasquet, R.; Zielinski, J. J.; De Temmerman, G.
2013-01-01
Experiments were performed in the Pilot-PSI linear plasma device, to determine the sheath heat transmission coefficients in a high recycling regime under various conditions of density (1–20 × 1020 m−3) and plasma composition (H2, Ar, N2) relevant for the
Sigaut, Lorena; Villarruel, Cecilia; Ponce, María Laura; Ponce Dawson, Silvina
2017-06-01
Many cell signaling pathways involve the diffusion of messengers that bind and unbind to and from intracellular components. Quantifying their net transport rate under different conditions then requires having separate estimates of their free diffusion coefficient and binding or unbinding rates. In this paper, we show how performing sets of fluorescence correlation spectroscopy (FCS) experiments under different conditions, it is possible to quantify free diffusion coefficients and on and off rates of reaction-diffusion systems. We develop the theory and present a practical implementation for the case of the universal second messenger, calcium (Ca2 +) and single-wavelength dyes that increase their fluorescence upon Ca2 + binding. We validate the approach with experiments performed in aqueous solutions containing Ca2 + and Fluo4 dextran (both in its high and low affinity versions). Performing FCS experiments with tetramethylrhodamine-dextran in Xenopus laevis oocytes, we infer the corresponding free diffusion coefficients in the cytosol of these cells. Our approach can be extended to other physiologically relevant reaction-diffusion systems to quantify biophysical parameters that determine the dynamics of various variables of interest.
Using the correlation coefficient
Krijnen, Wim
2015-01-01
De correlatie coeffcient wordt gedefinieerd en haar eigenschappen worden samengevat. Een tweetal andere coeffcienten worden gegeven voor het geval de metingen niet normaal verdeeld zijn. Met enkele voorbeelden wordt het gebruik toegelicht. In het kort wordt uitgelegd hoe onderzoekers een uitkomst we
Using the correlation coefficient
W.P. Krijnen
2015-01-01
De correlatie coeffcient wordt gedefinieerd en haar eigenschappen worden samengevat. Een tweetal andere coeffcienten worden gegeven voor het geval de metingen niet normaal verdeeld zijn. Met enkele voorbeelden wordt het gebruik toegelicht. In het kort wordt uitgelegd hoe onderzoekers een uitkomst
An apparatus for high temperature measurement of the resistivity and Hall coefficient
DEFF Research Database (Denmark)
Borup, Kasper Andersen; Toberer, Eric; Snyder, G Jeffrey
Two instruments implementing the van der Pauw (VDP) method for measuring the specific resistivity and Hall coefficient at high temperatures are described. Several features to minimize the measurement errors are proposed and some of the advantages compared with traditional six-probe combined...... resistivity and Hall coefficient measurements are outlined. The VDP method is convenient for use in thermoelectrics research since it accepts sample geometries compatible with measurements of the Seebeck coefficient and thermal diffusivity. This allows for the thermoelectric figure of merit to be measured...... using a single sample and without shaping the sample between measurement of individual properties. The technique is simple and can be used with samples showing a broad range of shapes and physical properties, from near insulators to metals. The two instruments are currently in use at Caltech...
Kim, Eun Jeong; Kim, Sung Hun; Park, Ga Eun; Kang, Bong Joo; Song, Byung Joo; Kim, Yun Ju; Lee, Dongeon; Ahn, Hyunsoo; Kim, Inah; Son, Yo Han; Grimm, Robert
2015-12-01
To evaluate apparent diffusion coefficient (ADC) histogram parameters that show correlations with prognostic factors and subtypes of breast cancer. At 3.0T, various ADC histogram parameters were calculated including the entire tumor volume in 173 invasive ductal carcinomas: the minimum, 10th percentile, mean, median, 90th percentile, and maximum. ADC parameters were correlated with prognostic factors and subtype. The mean ADCmedian value was significantly higher in the group with lymph node metastasis, HER2 positivity, and a Ki-67 value correlation between ADCmedian and tumor size, histologic grade, estrogen receptor expression, and progesterone receptor expression (P = 0.272, 0.113, 0.261, and 0.181, respectively). For most ADC parameters except for ADCmin , the mean of variable ADC parameters of HER2-positive, luminal A, luminal B-HER2(+), triple-negative, and luminal B-HER2(-) diseases were arranged in descending order (1.175, 0.936, 0.863, 0.811, and 0.665 × 10(-3) mm(2) /s in ADCmedian , respectively) with statistical significant difference (P coefficient = -0.317). Various ADC parameters were correlated with prognostic factors and subtype, except for ADCmin . HER2 positivity showed high ADC values and high Ki-67 index revealed low ADC values. © 2015 Wiley Periodicals, Inc.
Driessen, Juliette P; van Bemmel, Alexander J M; van Kempen, Pauline M W; Janssen, Luuk M; Terhaard, Chris H J; Pameijer, Frank A; Willems, Stefan M; Stegeman, Inge; Grolman, Wilko; Philippens, Marielle E P
2016-04-01
Identification of prognostic patient characteristics in head and neck squamous cell carcinoma (HNSCC) is of great importance. Human papillomavirus (HPV)-positive HNSCCs have favorable response to (chemo)radiotherapy. Apparent diffusion coefficient, derived from diffusion-weighted MRI, has also shown to predict treatment response. The purpose of this study was to evaluate the correlation between HPV status and apparent diffusion coefficient. Seventy-three patients with histologically proven HNSCC were retrospectively analyzed. Mean pretreatment apparent diffusion coefficient was calculated by delineation of total tumor volume on diffusion-weighted MRI. HPV status was analyzed and correlated to apparent diffusion coefficient. Six HNSCCs were HPV-positive. HPV-positive HNSCC showed significantly lower apparent diffusion coefficient compared to HPV-negative. This correlation was independent of other patient characteristics. In HNSCC, positive HPV status correlates with low mean apparent diffusion coefficient. The favorable prognostic value of low pretreatment apparent diffusion coefficient might be partially attributed to patients with a positive HPV status. © 2015 Wiley Periodicals, Inc. Head Neck 38: E613-E618, 2016. © 2015 Wiley Periodicals, Inc.
Braschel, Melissa C; Svec, Ivana; Darlington, Gerarda A; Donner, Allan
2016-04-01
Many investigators rely on previously published point estimates of the intraclass correlation coefficient rather than on their associated confidence intervals to determine the required size of a newly planned cluster randomized trial. Although confidence interval methods for the intraclass correlation coefficient that can be applied to community-based trials have been developed for a continuous outcome variable, fewer methods exist for a binary outcome variable. The aim of this study is to evaluate confidence interval methods for the intraclass correlation coefficient applied to binary outcomes in community intervention trials enrolling a small number of large clusters. Existing methods for confidence interval construction are examined and compared to a new ad hoc approach based on dividing clusters into a large number of smaller sub-clusters and subsequently applying existing methods to the resulting data. Monte Carlo simulation is used to assess the width and coverage of confidence intervals for the intraclass correlation coefficient based on Smith's large sample approximation of the standard error of the one-way analysis of variance estimator, an inverted modified Wald test for the Fleiss-Cuzick estimator, and intervals constructed using a bootstrap-t applied to a variance-stabilizing transformation of the intraclass correlation coefficient estimate. In addition, a new approach is applied in which clusters are randomly divided into a large number of smaller sub-clusters with the same methods applied to these data (with the exception of the bootstrap-t interval, which assumes large cluster sizes). These methods are also applied to a cluster randomized trial on adolescent tobacco use for illustration. When applied to a binary outcome variable in a small number of large clusters, existing confidence interval methods for the intraclass correlation coefficient provide poor coverage. However, confidence intervals constructed using the new approach combined with Smith
2015-04-28
Framework with High Seebeck Coefficient and Low Thermal Conductivity A new thermoelectric material with high Seebeck coefficient and low thermal conductivity ...MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 thermal conductivity ...Thermoelectric Metal-Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity Report Title A new thermoelectric material with high Seebeck
Er, Hale Çolakoğlu; Erden, Ayşe; Küçük, N Özlem; Geçim, Ethem
2014-01-01
The aim of this study was to retrospectively assess the correlation between minimum apparent diffusion coefficient (ADCmin) values obtained from diffusion-weighted magnetic resonance imaging (MRI) and maximum standardized uptake values (SUVmax) obtained from positron emission tomography-computed tomography (PET-CT) in rectal cancer. Forty-one patients with pathologically confirmed rectal adenocarcinoma were included in this study. For preoperative staging, PET-CT and pelvic MRI with diffusion-weighted imaging were performed within one week (mean time interval, 3±1 day). For ADC measurements, the region of interest (ROI) was manually drawn along the border of each hyperintense tumor on b=1000 s/mm2 images. After repeating this procedure on each consecutive tumor-containing slice to cover the entire tumoral area, ROIs were copied to ADC maps. ADCmin was determined as the lowest ADC value among all ROIs in each tumor. For SUVmax measurements, whole-body images were assessed visually on transaxial, sagittal, and coronal images. ROIs were determined from the lesions observed on each slice, and SUVmax values were calculated automatically. The mean values of ADCmin and SUVmax were compared using Spearman's test. The mean ADCmin was 0.62±0.19×10-3 mm2/s (range, 0.368-1.227×10-3 mm2/s), the mean SUVmax was 20.07±9.3 (range, 4.3-49.5). A significant negative correlation was found between ADCmin and SUVmax (r=-0.347; P = 0.026). There was a significant negative correlation between the ADCmin and SUVmax values in rectal adenocarcinomas.
Directory of Open Access Journals (Sweden)
Sherwan E. Tofiq
2016-06-01
Full Text Available The present study was conducted at Agricultural Research Center of Bakrajo, Sulaimani, Iraq during three successive seasons 2011-2014. This research was conducted using seven faba bean cultivars namely (Zaina, Seher, Yieldiz, Civilla, Luz di Otono, Tanyari and local. The following measurements and observations were made: 100 seed weight, first node height, number of seeds/plant, number of seeds/pod, pod length, number of pods/plant and seed yield. The results indicated that highly significant and negative correlations were presented between 100 seed weight and seed yield, whereas, significant and positive correlations were presented between the numbers of seed/plant and seed yield at the second season. In addition, the results of the third season indicate that the number of seeds/plant correlated significantly and positively with seed yield, and the number of seeds/pod correlated significantly and negatively with seed yield, whereas, number of pods/plant correlated high significantly and positively with the seed yield. The character first node height showed maximum direct effect value in seed yield at the first season and the third season, while number of pods/plant showed maximum direct effect value in seed yield at the second season.
Cai, Chen-Bo; Xu, Lu; Han, Qing-Juan; Wu, Hai-Long; Nie, Jin-Fang; Fu, Hai-Yan; Yu, Ru-Qin
2010-05-15
The paper focuses on solving a common and important problem of NIR quantitative analysis in multi-component systems: how to significantly reduce the size of the calibration set while not impairing the predictive precision. To cope with the problem orthogonal discrete wavelet packet transform (WPT), the least correlation design and correlation coefficient test (r-test) have been combined together. As three examples, a two-component carbon tetrachloride system with 21 calibration samples, a two-component aqueous system with 21 calibration samples, and a two-component aqueous system with 41 calibration samples have been treated with the proposed strategy, respectively. In comparison with some previous methods based on much more calibration samples, the results out of the strategy showed that the predictive ability was not obviously decreased for the first system while being clearly strengthened for the second one, and the predictive precision out of the third one was even satisfactory enough for most cases of quantitative analysis. In addition, all important factors and parameters related to our strategy are discussed in detail.
Zedler, S. E.
2009-04-25
The drag coefficient parameterization of wind stress is investigated for tropical storm conditions using model sensitivity studies. The Massachusetts Institute of Technology (MIT) Ocean General Circulation Model was run in a regional setting with realistic stratification and forcing fields representing Hurricane Frances, which in early September 2004 passed east of the Caribbean Leeward Island chain. The model was forced with a NOAA-HWIND wind speed product after converting it to wind stress using four different drag coefficient parameterizations. Respective model results were tested against in situ measurements of temperature profiles and velocity, available from an array of 22 surface drifters and 12 subsurface floats. Changing the drag coefficient parameterization from one that saturated at a value of 2.3 × 10 -3 to a constant drag coefficient of 1.2 × 10-3 reduced the standard deviation difference between the simulated minus the measured sea surface temperature change from 0.8°C to 0.3°C. Additionally, the standard deviation in the difference between simulated minus measured high pass filtered 15-m current speed reduced from 15 cm/s to 5 cm/s. The maximum difference in sea surface temperature response when two different turbulent mixing parameterizations were implemented was 0.3°C, i.e., only 11% of the maximum change of sea surface temperature caused by the storm. Copyright 2009 by the American Geophysical Union.
Zedler, S. E.; Niiler, P. P.; Stammer, D.; Terrill, E.; Morzel, J.
2009-04-01
The drag coefficient parameterization of wind stress is investigated for tropical storm conditions using model sensitivity studies. The Massachusetts Institute of Technology (MIT) Ocean General Circulation Model was run in a regional setting with realistic stratification and forcing fields representing Hurricane Frances, which in early September 2004 passed east of the Caribbean Leeward Island chain. The model was forced with a NOAA-HWIND wind speed product after converting it to wind stress using four different drag coefficient parameterizations. Respective model results were tested against in situ measurements of temperature profiles and velocity, available from an array of 22 surface drifters and 12 subsurface floats. Changing the drag coefficient parameterization from one that saturated at a value of 2.3 × 10-3 to a constant drag coefficient of 1.2 × 10-3 reduced the standard deviation difference between the simulated minus the measured sea surface temperature change from 0.8°C to 0.3°C. Additionally, the standard deviation in the difference between simulated minus measured high pass filtered 15-m current speed reduced from 15 cm/s to 5 cm/s. The maximum difference in sea surface temperature response when two different turbulent mixing parameterizations were implemented was 0.3°C, i.e., only 11% of the maximum change of sea surface temperature caused by the storm.
Institute of Scientific and Technical Information of China (English)
Wen-zhi ZHANG; Pei-yan HUANG
2014-01-01
Based on the precise integration method (PIM), a coupling technique of the high order multiplication perturbation method (HOMPM) and the reduction method is proposed to solve variable coefficient singularly perturbed two-point boundary value prob-lems (TPBVPs) with one boundary layer. First, the inhomogeneous ordinary differential equations (ODEs) are transformed into the homogeneous ODEs by variable coefficient dimensional expansion. Then, the whole interval is divided evenly, and the transfer ma-trix in each sub-interval is worked out through the HOMPM. Finally, a group of algebraic equations are given based on the relationship between the neighboring sub-intervals, which are solved by the reduction method. Numerical results show that the present method is highly efficient.
Asimakopoulos, Panagiotis; Bongiorno, M; Thiringer, T
2016-01-01
This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.
Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes
Pezo Milada L.; Stevanović Vladimir D.
2016-01-01
This paper presents CFD (Computational Fluid Dynamics) approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surfa...
Sound velocity of high-strength polymer with negative thermal expansion coefficient
Energy Technology Data Exchange (ETDEWEB)
Nomura, R.; Ueno, M.; Okuda, Y.; Burmistrov, S.; Yamanaka, A
2003-05-01
Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber.
A Note about the Calculation of Partial Correlation Coefficient%关于偏相关系数的计算公式的一点注记
Institute of Scientific and Technical Information of China (English)
陈敏琼; 彭东海
2014-01-01
On the partial correlation coefficient ,the paper sums up the definitions and calculation meth-ods of commonly used and derives the method to calculate the partial correlation coefficient formula by the correlation coefficient matrix and covariance matrix inversion from the multivariate normal distribu-tion theory of the conclusion of conditional distribution .Then the method to calculate the partial corre-lation coefficient formula by the correlation coefficient matrix inversion is given a reasonable explana-tion .%首先对偏相关系数的常用的定义与计算方法作了归纳，然后从多元正态分布理论中的条件分布的结论出发，推导得出通过相关系数阵或协方差阵求逆的方法来计算偏相关系数的公式，从而对利用相关系数阵求逆方法计算偏相关系数的公式给出了合理的解释。
Oh, Ji-Won; Rha, Sung Eun; Oh, Soon Nam; Park, Michael Yong; Byun, Jae Young; Lee, Ahwon
2015-04-01
The purpose of this article is to correlate the apparent diffusion coefficient (ADC) values of epithelial ovarian cancers with histologic grade and surgical stage. We enrolled 43 patients with pathologically proven epithelial ovarian cancers for this retrospective study. All patients underwent preoperative pelvic magnetic resonance imaging (MRI) including diffusion-weighted images with b value of 0 and 1000 s/mm2 at 3.0-T unit. The mean ADC values of the solid portion of the tumor were measured and compared among different histologic grades and surgical stages. The mean ADC values of epithelial ovarian cancers differed significantly between grade 1 (well-differentiated) and grade 2 (moderately-differentiated) (P=0.013) as well as between grade 1 and grade 3 (poorly-differentiated) (P=0.01); however, no statistically significant difference existed between grade 2 and grade 3 (P=0.737). The receiver-operating characteristic analysis indicated that a cutoff ADC value of less than or equal to 1.09×10(-3)mm2/s was associated with 94.4% sensitivity and 85.7% specificity in distinguishing grade 1 and grade 2/3 cancer. The difference in mean ADC values was statistically significant for early stage (FIGO stage I) and advanced stage (FIGO stage II-IV) cancer (P=0.011). The interobserver agreement for the mean ADC values of epithelial ovarian cancers was excellent. The mean ADC values of the solid portion of epithelial ovarian cancers negatively correlated to histologic grade and surgical stage. The mean ADC values may be useful imaging biomarkers for assessment of tumor grade of epithelial ovarian cancer. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Diffraction Correlation to Reconstruct Highly Strained Particles
Brown, Douglas; Harder, Ross; Clark, Jesse; Kim, J. W.; Kiefer, Boris; Fullerton, Eric; Shpyrko, Oleg; Fohtung, Edwin
2015-03-01
Through the use of coherent x-ray diffraction a three-dimensional diffraction pattern of a highly strained nano-crystal can be recorded in reciprocal space by a detector. Only the intensities are recorded, resulting in a loss of the complex phase. The recorded diffraction pattern therefore requires computational processing to reconstruct the density and complex distribution of the diffracted nano-crystal. For highly strained crystals, standard methods using HIO and ER algorithms are no longer sufficient to reconstruct the diffraction pattern. Our solution is to correlate the symmetry in reciprocal space to generate an a priori shape constraint to guide the computational reconstruction of the diffraction pattern. This approach has improved the ability to accurately reconstruct highly strained nano-crystals.
Büttner, Kathrin; Salau, Jennifer; Krieter, Joachim
2016-01-01
The average topological overlap of two graphs of two consecutive time steps measures the amount of changes in the edge configuration between the two snapshots. This value has to be zero if the edge configuration changes completely and one if the two consecutive graphs are identical. Current methods depend on the number of nodes in the network or on the maximal number of connected nodes in the consecutive time steps. In the first case, this methodology breaks down if there are nodes with no edges. In the second case, it fails if the maximal number of active nodes is larger than the maximal number of connected nodes. In the following, an adaption of the calculation of the temporal correlation coefficient and of the topological overlap of the graph between two consecutive time steps is presented, which shows the expected behaviour mentioned above. The newly proposed adaption uses the maximal number of active nodes, i.e. the number of nodes with at least one edge, for the calculation of the topological overlap. The three methods were compared with the help of vivid example networks to reveal the differences between the proposed notations. Furthermore, these three calculation methods were applied to a real-world network of animal movements in order to detect influences of the network structure on the outcome of the different methods.
Wu, Sheng; Crespi, Catherine M; Wong, Weng Kee
2012-09-01
The intraclass correlation coefficient (ICC) is a fundamental parameter of interest in cluster randomized trials as it can greatly affect statistical power. We compare common methods of estimating the ICC in cluster randomized trials with binary outcomes, with a specific focus on their application to community-based cancer prevention trials with primary outcome of self-reported cancer screening. Using three real data sets from cancer screening intervention trials with different numbers and types of clusters and cluster sizes, we obtained point estimates and 95% confidence intervals for the ICC using five methods: the analysis of variance estimator, the Fleiss-Cuzick estimator, the Pearson estimator, an estimator based on generalized estimating equations and an estimator from a random intercept logistic regression model. We compared estimates of the ICC for the overall sample and by study condition. Our results show that ICC estimates from different methods can be quite different, although confidence intervals generally overlap. The ICC varied substantially by study condition in two studies, suggesting that the common practice of assuming a common ICC across all clusters in the trial is questionable. A simulation study confirmed pitfalls of erroneously assuming a common ICC. Investigators should consider using sample size and analysis methods that allow the ICC to vary by study condition.
Yang, Tao; Zhang, Feipeng; Yardimci, Galip Gurkan; Song, Fan; Hardison, Ross C; Noble, William Stafford; Yue, Feng; Li, Qunhua
2017-08-30
Hi-C is a powerful technology for studying genome-wide chromatin interactions. However, current methods for assessing Hi-C data reproducibility can produce misleading results because they ignore spatial features in Hi-C data, such as domain structure and distance dependence. We present HiCRep, a framework for assessing the reproducibility of Hi-C data that systematically accounts for these features. In particular, we introduce a novel similarity measure, the stratum adjusted correlation coefficient (SCC), for quantifying the similarity between Hi-C interaction matrices. Not only does it provide a statistically sound and reliable evaluation of reproducibility, SCC can also be used to quantify differences between Hi-C contact matrices and to determine the optimal sequencing depth for a desired resolution. The measure consistently shows higher accuracy than existing approaches in distinguishing subtle differences in reproducibility and depicting interrelationships of cell lineages. The proposed measure is straightforward to interpret and easy to compute, making it well-suited for providing standardized, interpretable, automatable, and scalable quality control. The freely available R package HiCRep implements our approach. Published by Cold Spring Harbor Laboratory Press.
Ibrahim, E A; Ramadan, A Y
2013-07-01
Genotypic correlation and path analyses were carried out for growth, yield and fruit quality traits in 13 sweet melon genotypes collected from different places in Egypt. Seeds of these melon populations were sown under irrigated and drought stress conditions. The analysis of variance for the studied traits showed that the differences among genotypes were highly significant for all studied traits under irrigation and drought stress. Under irrigated conditions, total yield per plant was positively and significantly correlated with fruit weight, flesh fruit thickness and fruit length. Positive direct effects were exhibited for fruit weight, number of fruits per plant and stem length on total yield per plant, while maximum positive indirect effects on total yield per plant were exhibited by fruit length and flesh fruit thickness through fruit weight. In case of drought stress conditions, total yield per plant had the highest positive and significant correlation with fruit weight followed by flesh fruit thickness, fruit length and stem length. Fruit weight had the greatest positive direct effect on total yield per plant followed by number of fruits per plant, fruit length and total soluble solid content. Flesh fruit thickness and fruit length had high positive indirect effect on total yield per plant via fruit weight. The results obtained from correlation and path analyses showed that the efficiency in the selection for total yield per plant in sweet melon should increased through the selection of fruit weight under irrigated conditions and fruit weight and fruit length under drought conditions.
Directory of Open Access Journals (Sweden)
Anwar Fitrianto
2014-01-01
Full Text Available When independent variables have high linear correlation in a multiple linear regression model, we can have wrong analysis. It happens if we do the multiple linear regression analysis based on common Ordinary Least Squares (OLS method. In this situation, we are suggested to use ridge regression estimator. We conduct some simulation study to compare the performance of ridge regression estimator and the OLS. We found that Hoerl and Kennard ridge regression estimation method has better performance than the other approaches.
Cui, Wansong; Wang, Difeng; Gong, Fang; Bai, Yan; Zhang, Lin; Zhu, Qiankun; Chen, Peng
2016-10-01
The beam attenuation coefficient (c), an inherent optical property of water, can provide information about the particulate matter in the water. In this study, the vertical distribution of the particulate beam attenuation coefficient at 660 nm (cp(660)) and its correlation to the particulate organic carbon (POC) and chlorophyll a (Chl-a) concentrations in the north South China Sea (NSCS), was investigated based on the in situ data from two cruises covering the summer and autumn seasons during 2009-2010year. The results showed that in summer, the profiles of cp(660) at the near shore stations were generally well vertical mixed, except at the bottom layer where cp(660) sharply increased due to sediment resuspension. However, in the slope and basin, the profiles of cp(660) had the peak value in the subsurface layer, and the depth of maximum increased with the increasing of the water depth. The subsurface maximum of the cp(660) was corresponding to the subsurface maximum Chl-a in the shelf and basin in the NSCS in summer. In autumn, the depth profile of cp(660) was also well mixed in the near shore, similar as it in summer. In the basin, unlike the subsurface maximum in summer, cp(660) had the decreasing trend with the increasing of depth in most stations in autumn. The spatial distribution pattern of the surface cp(660) was similar in the two seasons, with high values in near shore and low values in the shelf and basin. This was mainly attributed to the river and terrigenous organic materials. There were good correlations between cp(660) and POC in both seasons, except some near shore stations with high sediment resuspension. That made the possibility of estimating the POC profile using the cp(660), and further calculating the vertical structure with satellite-derived surface POC.
Istomin, V. A.; Kustova, E. V.
2017-02-01
The influence of electronic excitation on transport processes in non-equilibrium high-temperature ionized mixture flows is studied. Two five-component mixtures, N 2 / N2 + / N / N + / e - and O 2 / O2 + / O / O + / e - , are considered taking into account the electronic degrees of freedom for atomic species as well as the rotational-vibrational-electronic degrees of freedom for molecular species, both neutral and ionized. Using the modified Chapman-Enskog method, the transport coefficients (thermal conductivity, shear viscosity and bulk viscosity, diffusion and thermal diffusion) are calculated in the temperature range 500-50 000 K. Thermal conductivity and bulk viscosity coefficients are strongly affected by electronic states, especially for neutral atomic species. Shear viscosity, diffusion, and thermal diffusion coefficients are not sensible to electronic excitation if the size of excited states is assumed to be constant. The limits of applicability for the Stokes relation are discussed; at high temperatures, this relation is violated not only for molecular species but also for electronically excited atomic gases. Two test cases of strongly non-equilibrium flows behind plane shock waves corresponding to the spacecraft re-entry (Hermes and Fire II) are simulated numerically. Fluid-dynamic variables and heat fluxes are evaluated in gases with electronic excitation. In inviscid flows without chemical-radiative coupling, the flow-field is weakly affected by electronic states; however, in viscous flows, their influence can be more important, in particular, on the convective heat flux. The contribution of different dissipative processes to the heat transfer is evaluated as well as the effect of reaction rate coefficients. The competition of diffusion and heat conduction processes reduces the overall effect of electronic excitation on the convective heating, especially for the Fire II test case. It is shown that reliable models of chemical reaction rates are of great
Jebaraj Johnley Muthuraj, Josiah
Cathodic protection is widely used for corrosion prevention. However, this process generates hydrogen at the protected metal surface, and diffusion of hydrogen through the metal may cause hydrogen embrittlement or hydrogen induced stress corrosion cracking. Thus the choice of a metal for use as fasteners depends upon its hydrogen uptake, permeation, diffusivity and trapping. The diffusivity of hydrogen through four high strength alloys (AISI 4340, alloy 718, alloy 686, and alloy 59) was analyzed by an electrochemical method developed by Devanathan and Stachurski. The effect of plasma nitriding and microstructure on hydrogen permeation through AISI 4340 was studied on six different specimens: as-received (AR) AISI 4340, nitrided samples with and without compound layer, samples quenched and tempered (Q&T) at 320° and 520°C, and nitrided samples Q&T 520°C. Studies on various nitrided specimens demonstrate that both the gamma'-Fe 4N rich compound surface layer and the deeper N diffusion layer that forms during plasma nitriding reduce the effective hydrogen diffusion coefficient, although the gamma'-Fe4N rich compound layer has a larger effect. Multiple permeation transients yield evidence for the presence of only reversible trap sites in as-received, Q&T 320 and 520 AISI 4340 specimens, and the presence of both reversible and irreversible trap sites in nitrided specimens. Moreover, the changes in microstructure during the quenching and tempering process result in a significant decrease in the diffusion coefficient of hydrogen compared to as-received specimens. In addition, density functional theory-based molecular dynamics simulations yield hydrogen diffusion coefficients through gamma'- Fe4N one order of magnitude lower than through α-Fe, which supports the experimental measurements of hydrogen permeation. The effect of microstructure and trapping was also studied in cold rolled, solutionized, and precipitation hardened Inconel 718 foils. The effective hydrogen
Energy Technology Data Exchange (ETDEWEB)
Jeong, Ju Hye [Dept. of Nuclear Medicine, Kyungpook National University Hospital, Daegu (Korea, Republic of); Cho, Ihn Ho; Chun, Kyung Ah; Kong, Eun Jung; Kwon, Sang Don; Kim, Jae Hwang [Yeungnam University Hospital, Daegu (Korea, Republic of)
2016-06-15
Fluorine-18-fluorodeoxyglucose ({sup 18}F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR. Nine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70 ± 15.91 years) underwent torso {sup 18}F-FDG PET/CT and regional hybrid {sup 18}F-FDG PET/MR sequentially. A fixed threshold value of 40 % of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUV{sub max}, SUV{sub peak}, and SUV{sub mean} were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman'rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values. SUV{sub max}, SUV{sub peak}, and SUV{sub mean} derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66 ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10{sup -3}mm{sup 2}/s. ADCmean was significantly and inversely correlated with SUV values (SUV{sub max}, ρ = -0.95, p < 0.001; SUV{sub peak}, ρ = -0.93, p < 0.001; SUV{sub mean}, ρ = -0.91, p = 0.001). This preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on {sup 18}F-FDG PET and water diffusion on DWI in rectal cancer.
Re-evaluation of SiC permeation coefficients at high temperatures
Energy Technology Data Exchange (ETDEWEB)
Yamamoto, Yasushi, E-mail: yama3707@kansai-u.ac.jp [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Murakami, Yuichiro; Yamaguchi, Hirosato; Yamamoto, Takehiro; Yonetsu, Daigo [Faculty of Engineering Science, Kansai Univ., Yamate-cho, Suita, Osaka 564-8680 (Japan); Noborio, Kazuyuki [Hydrogen Isotope Research Center, Univ. of Toyama, Toyama, Toyama 930-8555 (Japan); Konishi, Satoshi [Institute of Advanced Energy, Kyoto Univ., Gokasho, Uji, Kyoto 611-0011 (Japan)
2016-11-01
Highlights: • The deuterium permeation coefficients of CVD-SiC at 600–950 °C were evaluated. • The wraparound flow was reduced to less than 1/100th of the permeation flow. • CVD-SiC materials are very effective as hydrogen isotope permeation barriers. - Abstract: Since 2007, our group has studied the deuterium permeation and diffusion coefficients for SiC materials at temperatures above 600 °C as a means of evaluating the tritium inventory and permeation in fusion blankets. During such measurements, control and evaluation of the wraparound flow through the sample holder are important, and so the heated sample holder is enclosed by a glass tube and kept under vacuum during experimental trials. However, detailed studies regarding the required degree of vacuum based on model calculations have shown that the wraparound flow is much larger than expected, and so can affect measurements at high temperatures. We therefore modified the measurement apparatus based on calculations involving reduced pressure in the glass tube, and are now confident that the measurement error is only several percent, even at 950 °C. In this paper, recent experimental results obtained with a chemical vapor deposition (CVD)-SiC sample over the temperature range of 600–950 °C are presented, showing that the permeation coefficient for CVD-SiC is more than three orders of magnitude smaller than that for stainless steel (SS316) at 600 °C, and that at 950 °C, the coefficient for CVD-SiC is almost equal to that for SUS316 at 550 °C.
Institute of Scientific and Technical Information of China (English)
QIN Jianzhong; ZHENG Longju; Tenger
2007-01-01
On the basis of the results of hydropyrolysis simulations for about 90 different types of immature to mature source rocks selected from about 5 000 marine source rocks in China,along with the natural thermal evolution profiles,the following conclusions were obtained.(1) Total organic carbon (TOC) content of excellent marine source rocks does not change obviously when Ro＜0.8% or Ro ＞ 1.3%,and the residual TOC content is decreasing gradually with the maturity increase at 0.8% ＜Ro＜ 1.3%.(2) At the high-post mature stage (Ro ＞ 1.3%),the decreased maximums of residual TOC content for the kerogen of sapropel (Ⅰ),Ⅱ1,and Ⅱ are usually 40%,32% and 24%,respectively,and their TOC restitution coefficient is,respectively,1.68,1.48 and 1.32.(3)Both the TOC decreasing amplitude and the restitution coefficient decrease gradually with the decrease of TOC content for the source rocks with low organic matter abundance (usually 0.3% ＜ TOC ＜ 1.0%).The TOC restitution coefficients are,respectively,1.20 and 1.0,when 0.3%＜TOC＜0.5% and TOC ＜ 0.3%.(4) TOCres.of solid bitumen and shale with high organic matter abundance (TOC ＞ 30%) also require no restitution at the high mature stage.Such kind of TOC restitution is further supported by the coincidence of the decrease of residual TOC with the decreasing of S1 + S2 and the increasing of hydrocarbon quantity during the experimental simulation of hydrocarbon generation and expulsion for marine source rocks (0.3%＜TOC&＜30%) in natural thermal evolution profiles.
The Influence of wave state and sea spray on drag coefficient from low to high wind speeds
Shi, Jian; Zhong, Zhong; Li, Xunqiang; Jiang, Guorong; Zeng, Wenhua; Li, Yan
2016-02-01
Ocean waves alter the roughness of sea surface, and sea spray droplets redistribute the momentum flux at the air-sea interface. Hence, both wave state and sea spray influence sea surface drag coefficient. Based on the new sea spray generation function which depends on sea surface wave, a wave-dependent sea spray stress is obtained. According to the relationship between sea spray stress and the total wind stress on the sea surface, a new formula of drag coefficient at high wind speed is acquired. With the analysis of the new drag coefficient, it is shown that the drag coefficient reduces at high wind speed, indicating that the sea spray droplets can limit the increase of drag coefficient. However, the value of high wind speed corresponding to the initial reduced drag coefficient is not fixed, and it depends on the wave state, which means the influence of wave cannot be ignored. Comparisons between the theoretical and measured sea surface drag coefficients in field and laboratory show that under different wave ages, the theoretical result of drag coefficient could include the measured data, and it means that the new drag coefficient can be used properly from low to high wind speeds under any wave state condition.
Thin Film Chip Resistors with High Resistance and Low Temperature Coefficient of Resistance
Institute of Scientific and Technical Information of China (English)
王秀宇; 张之圣; 白天; 刘仲娥
2010-01-01
High resistance thin film chip resistors(0603 type) were studied,and the specifications are as follows:1 k? with tolerance about ±0.1% after laser trimming and temperature coefficient of resistance(TCR) less than ±15×10-6/℃.Cr-Si-Ta-Al films were prepared with Ar flow rate and sputtering power fixed at 20 standard-state cubic centimeter per minute(sccm) and 100 W,respectively.The experiment shows that the electrical properties of Cr-SiTa-Al deposition films can meet the specification requirements of 0603 ty...
Indian Academy of Sciences (India)
L Giribabu; Vrun Kumar Singh; M Srinivasu; Ch Vijay Kumar; V Gopal Reddy; Y Soujnya; P Yella Reddy
2011-07-01
A new high molar extinction coefficient heteroleptic ruthenium(II) complex (m-BL-1) that contains a 4,4'4"-tricaboxy-2,2':6’,2”-terpyridine, 4,4’-bis-[3,5-di-tert-butyl-phenyl)-vinyl]-[2,2']bipyridyl and a thiocyanate ligand in its molecular structure has been synthesized and completely characterized by CHN, Mass, 1H-NMR, UV-Vis, and fluorescence spectroscopies as well as cyclic voltammetry. The new sensitizer was tested in dye-sensitized solar cells using three different redox electrolytes and compared its performance to that of standard sensitizer black dye.
Chung, S.
1973-01-01
Heat transfer phenomena of rarefied gas flows is discussed based on a literature survey of analytical and experimental rarefied gas dynamics. Subsonic flows are emphasized for the purposes of meteorological thermometry in the high atmosphere. The heat transfer coefficients for three basic geometries are given in the regimes of free molecular flow, transition flow, slip flow, and continuum flow. Different types of heat phenomena, and the analysis of theoretical and experimental data are presented. The uncertainties calculated from the interpolation rule compared with the available experimental data are discussed. The recovery factor for each geometry in subsonic rarefied flows is also given.
Jin, Ying; Myers, Nicholas D.; Ahn, Soyeon
2014-01-01
Previous research has demonstrated that differential item functioning (DIF) methods that do not account for multilevel data structure could result in too frequent rejection of the null hypothesis (i.e., no DIF) when the intraclass correlation coefficient (?) of the studied item was the same as the ? of the total score. The current study extended…
Improvement of Similarity Measure:Pearson Product-Moment Correlation Coefficient%相似度的评价指标相关系数的改进
Institute of Scientific and Technical Information of China (English)
刘永锁; 孟庆华; 陈蓉; 王健松; 蒋淑敏; 胡育筑
2004-01-01
Aim To study the reason of the insensitiveness of Pearson product-moment correlation coefficient as a similarity measure and the method to improve its sensitivity. Methods Experimental and simulated data sets were used. Results The distribution range of the data sets influences the sensitivity of Pearson product-moment correlation coefficient.Weighted Pearson product-moment correlation coefficient is more sensitive when the range of the data set is large. Conclusion Weighted Pearson product-moment correlation coefficient is necessary when the range of the data set is large.%目的研究相似度的评价指标:相关系数的灵敏度低的原因及其改进的方法.方法利用实验数据和模拟数据研究相关系数的灵敏度低的问题.结果相关系数的灵敏度受数据的分布范围的影响,在数据的分布范围宽时加权相关系数更灵敏.结论在数据的分布范围宽时有必要进行加权运算.
Jin, Ying; Myers, Nicholas D.; Ahn, Soyeon
2014-01-01
Previous research has demonstrated that differential item functioning (DIF) methods that do not account for multilevel data structure could result in too frequent rejection of the null hypothesis (i.e., no DIF) when the intraclass correlation coefficient (?) of the studied item was the same as the ? of the total score. The current study extended…
Inchingolo, Riccardo; De Gaetano, Anna Maria; Curione, Davide; Ciresa, Marzia; Miele, Luca; Pompili, Maurizio; Vecchio, Fabio Maria; Giuliante, Felice; Bonomo, Lorenzo
2015-04-01
To investigate the utility of diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and the correlation with hepatobiliary phase (delayed phase imaging, DPI) findings in the differentiation of cirrhotic hepatocellular nodules. Forty-three patients with 53 pathology-proven nodules (29 hepatocellular carcinomas (HCCs), 13 high-grade (HGDNs) and 11 low-grade dysplastic nodules (LGDNs); mean size 2.17 cm, range 1-4 cm), who underwent liver MRI with DWI and DPI sequences, were retrospectively reviewed. Lesions were classified as hypointense, isointense, or hyperintense relative to the adjacent liver parenchyma. ADC of each nodule, of the surrounding parenchyma, and lesion-to-liver ratio were calculated. Hyperintensity versus iso/hypointensity on DWI, hypointensity versus iso/hyperintensity on DPI, and the mean lesion-to-liver ratio showed a statistically significant difference both between HCCs versus DNs and between "HCCs + HGDNs" versus LGDNs (p Correlation of DWI with DPI improves differential diagnosis of cirrhotic nodules. • Characterization of atypically enhancing lesions becomes more confident.
Experimental study on hydrodynamic coefficients for high-incidence-angle maneuver of a submarine
Directory of Open Access Journals (Sweden)
Jong-Yong Park
2017-01-01
Full Text Available Snap rolling during hard turning and instability during emergency rising are important features of submarine operation. Hydrodynamics modeling using a high incidence flow angle is required to predict these phenomena. In the present study, a quasi-steady dynamics model of a submarine suitable for high-incidence-angle maneuvering applications is developed. To determine the hydrodynamic coefficients of the model, static tests, dynamic tests, and control surface tests were conducted in a towing tank and wind tunnel. The towing tank test is conducted utilizing a Reynolds number of 3.12 × 106, and the wind tunnel test is performed utilizing a Reynolds number of 5.11 × 106. In addition, least squares, golden section search, and surface fitting using polynomial models were used to analyze the experimental results. The obtained coefficients are presented in tabular form and can be used for various purposes such as hard turning simulation, emergency rising simulation, and controller design.
Thompson, Stephen C; Meyer, Richard J; Markley, Douglas C
2014-01-01
Tonpilz acoustic transducers for use underwater often include a stack of piezoelectric material pieces polarized along the length of the stack and having alternating polarity. The pieces are interspersed with electrodes, bonded together, and electrically connected in parallel. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, for example, with lead zirconate titanate (PZT) material, stack segmentation has no significant effect on the mechanical behavior of the device in its normal operating band near the fundamental resonance. However, when a high coupling coefficient material such as lead magnesium niobate-lead titanate (PMN-PT) is used to achieve a wider bandwidth with the tonpilz, the performance difference between a segmented stack and a similar piezoelectric section with electrodes only at the two ends can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater tonpilz acoustic transducers. Included is a discussion of a particular tonpilz transducer design using single crystal piezoelectric material with high coupling coefficient compared with a similar design using more traditional PZT ceramics.
Gray, Heewon Lee; Burgermaster, Marissa; Tipton, Elizabeth; Contento, Isobel R; Koch, Pamela A; Di Noia, Jennifer
2016-04-01
Sample size and statistical power calculation should consider clustering effects when schools are the unit of randomization in intervention studies. The objective of the current study was to investigate how student outcomes are clustered within schools in an obesity prevention trial. Baseline data from the Food, Health & Choices project were used. Participants were 9- to 13-year-old students enrolled in 20 New York City public schools (n= 1,387). Body mass index (BMI) was calculated based on measures of height and weight, and body fat percentage was measured with a Tanita® body composition analyzer (Model SC-331s). Energy balance-related behaviors were self-reported with a frequency questionnaire. To examine the cluster effects, intraclass correlation coefficients (ICCs) were calculated as school variance over total variance for outcome variables. School-level covariates, percentage students eligible for free and reduced-price lunch, percentage Black or Hispanic, and English language learners were added in the model to examine ICC changes. The ICCs for obesity indicators are: .026 for BMI-percentile, .031 for BMIz-score, .035 for percentage of overweight students, .037 for body fat percentage, and .041 for absolute BMI. The ICC range for the six energy balance-related behaviors are .008 to .044 for fruit and vegetables, .013 to .055 for physical activity, .031 to .052 for recreational screen time, .013 to .091 for sweetened beverages, .033 to .121 for processed packaged snacks, and .020 to .083 for fast food. When school-level covariates were included in the model, ICC changes varied from -95% to 85%. This is the first study reporting ICCs for obesity-related anthropometric and behavioral outcomes among New York City public schools. The results of the study may aid sample size estimation for future school-based cluster randomized controlled trials in similar urban setting and population. Additionally, identifying school-level covariates that can reduce cluster
Chirico, Nicola; Gramatica, Paola
2011-09-26
The main utility of QSAR models is their ability to predict activities/properties for new chemicals, and this external prediction ability is evaluated by means of various validation criteria. As a measure for such evaluation the OECD guidelines have proposed the predictive squared correlation coefficient Q(2)(F1) (Shi et al.). However, other validation criteria have been proposed by other authors: the Golbraikh-Tropsha method, r(2)(m) (Roy), Q(2)(F2) (Schüürmann et al.), Q(2)(F3) (Consonni et al.). In QSAR studies these measures are usually in accordance, though this is not always the case, thus doubts can arise when contradictory results are obtained. It is likely that none of the aforementioned criteria is the best in every situation, so a comparative study using simulated data sets is proposed here, using threshold values suggested by the proponents or those widely used in QSAR modeling. In addition, a different and simple external validation measure, the concordance correlation coefficient (CCC), is proposed and compared with other criteria. Huge data sets were used to study the general behavior of validation measures, and the concordance correlation coefficient was shown to be the most restrictive. On using simulated data sets of a more realistic size, it was found that CCC was broadly in agreement, about 96% of the time, with other validation measures in accepting models as predictive, and in almost all the examples it was the most precautionary. The proposed concordance correlation coefficient also works well on real data sets, where it seems to be more stable, and helps in making decisions when the validation measures are in conflict. Since it is conceptually simple, and given its stability and restrictiveness, we propose the concordance correlation coefficient as a complementary, or alternative, more prudent measure of a QSAR model to be externally predictive.
Park, Eun Kyung; Cho, Kyu Ran; Seo, Bo Kyoung; Woo, Ok Hee; Cho, Sung Bum; Bae, Jeoung Won
2016-01-01
Breast cancer is a heterogeneous disease with diverse prognoses. The main prognostic determinants are lymph node status, tumor size, histological grade, and biological factors, such as hormone receptors, human epidermal growth factor receptor 2 (HER2), Ki-67 protein levels, and p53 expression. Diffusion-weighted imaging (DWI) can be used to measure the apparent diffusion coefficient (ADC) that provides information related to tumor cellularity and the integrity of the cell membranes. The goal of this study was to evaluate whether ADC measurements could provide information on the prognostic factors of breast cancer. A total of 71 women with invasive breast cancer, treated consecutively, who underwent preoperative breast MRIs with DWI at 3.0 Tesla and subsequent surgery, were prospectively included in this study. Each DWI was acquired with b values of 0 and 1000 s/mm(2). The mean ADC values of the lesions were measured, including the entire lesion on the three largest sections. We performed histopathological analyses for the tumor size, lymph node status, histological grade, hormone receptors, human epidermal growth factor receptor 2 (HER2), Ki-67, p53, and molecular subtypes. The associations with the ADC values and prognostic factors of breast cancer were evaluated using the independent-samples t test and the one-way analysis of variance (ANOVA). A low ADC value was associated with lymph node metastasis (P < 0.01) and with high Ki-67 protein levels (P = 0.03). There were no significant differences in the ADC values among the histological grade (P = 0.48), molecular subtype (P = 0.51), tumor size (P = 0.46), and p53 protein level (P = 0.62). The pre-operative use of the 3.0 Tesla DWI could provide information about the lymph node status and tumor proliferation for breast cancer patients, and could help determine the optimal treatment plan.
Klöckner, Wolf; Gacem, Riad; Anderlei, Tibor; Raven, Nicole; Schillberg, Stefan; Lattermann, Clemens; Büchs, Jochen
2013-12-02
Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham's π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/- 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale.
High-order virial coefficients and equation of state for hard sphere and hard disk systems.
Hu, Jiawen; Yu, Yang-Xin
2009-11-07
A very simple and accurate approach is proposed to predict the high-order virial coefficients of hard spheres and hard disks. In the approach, the nth virial coefficient B(n) is expressed as the sum of n(D-1) and a remainder, where D is the spatial dimension of the system. When n > or = 3, the remainders of the virials can be accurately expressed with Padé-type functions of n. The maximum deviations of predicted B(5)-B(10) for the two systems are only 0.0209%-0.0044% and 0.0390%-0.0525%, respectively, which are much better than the numerous existing approaches. The virial equation based on the predicted virials diverges when packing fraction eta = 1. With the predicted virials, the compressibility factors of hard sphere system can be predicted very accurately in the whole stable fluid region, and those in the metastable fluid region can also be well predicted up to eta = 0.545. The compressibility factors of hard disk fluid can be predicted very accurately up to eta = 0.63. The simulated B(7) and B(10) for hard spheres are found to be inconsistent with the other known virials and therefore they are modified as 53.2467 and 105.042, respectively.
Nonparametric Independence Screening in Sparse Ultra-High Dimensional Varying Coefficient Models.
Fan, Jianqing; Ma, Yunbei; Dai, Wei
2014-01-01
The varying-coefficient model is an important class of nonparametric statistical model that allows us to examine how the effects of covariates vary with exposure variables. When the number of covariates is large, the issue of variable selection arises. In this paper, we propose and investigate marginal nonparametric screening methods to screen variables in sparse ultra-high dimensional varying-coefficient models. The proposed nonparametric independence screening (NIS) selects variables by ranking a measure of the nonparametric marginal contributions of each covariate given the exposure variable. The sure independent screening property is established under some mild technical conditions when the dimensionality is of nonpolynomial order, and the dimensionality reduction of NIS is quantified. To enhance the practical utility and finite sample performance, two data-driven iterative NIS methods are proposed for selecting thresholding parameters and variables: conditional permutation and greedy methods, resulting in Conditional-INIS and Greedy-INIS. The effectiveness and flexibility of the proposed methods are further illustrated by simulation studies and real data applications.
Zhan, Yuefu; Liang, Xianwen; Han, Xiangjun; Chen, Jianqiang; Zhang, Shufang; Tan, Shun; Li, Qun; Wang, Xiong; Liu, Fan
2017-02-28
To explore the correlation between the apparent diffusion coefficient (ADC) and mRNA expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) in different stages of liver fibrosis in rats. Methods: A model of liver fibrosis in rats was established by intraperitoneal injection of high-fat diet combined with porcine serum. After drug administration for 4 weeks, 48 rats served as a model group and 12 rats served as a control group, then they underwent diffusion weighted imaging (DWI) scanning. The value of ADC was calculated at b value=800 s/mm2. The rats were sacrificed and carried out pathologic examination after DWI scanning immediately. The mRNA expression of TIMP-1 was detected by real time-polymerase chain reaction (RT-PCR). The rats of hepatic fibrosis were also divided into a S0 group (n=4), a S1 group (n=11), a S2 group (n=12), a S3 group (n=10), and a S4 group (n=9) according to their pathological stage. The value of ADC and the expression of TIMP-1 mRNA among the different stage groups of liver fibrosis were compared, and the correlation between ADC and the TIMP-1 mRNA were analyzed. Results: The ADC value and the TIMP-1 mRNA expression were significantly different between the control group and the liver fibrosis group (F=46.54 and 53.87, P0.05). For the comparison of TIMP-1 mRNA, there was no significant difference between the S1 group and the S2 group, the S3 group and the S4 group (both P>0.05). There were significant differences among the rest of the groups (all Pcorrelation analysis showed that there was a negative correlation between the ADC value and the TIMP-1 mRNA expression (r=-0.76, Pcorrelation between them.
Directory of Open Access Journals (Sweden)
Gang-Jin Wang
2013-05-01
Full Text Available We investigate the statistical properties of the foreign exchange (FX network at different time scales by two approaches, namely the methods of detrended cross-correlation coefficient (DCCA coefficient and minimum spanning tree (MST. The daily FX rates of 44 major currencies in the period of 2007–2012 are chosen as the empirical data. Based on the analysis of statistical properties of cross-correlation coefficients, we find that the cross-correlation coefficients of the FX market are fat-tailed. By examining three MSTs at three special time scales (i.e., the minimum, medium, and maximum scales, we come to some conclusions: USD and EUR are confirmed as the predominant world currencies; the Middle East cluster is very stable while the Asian cluster and the Latin America cluster are not stable in the MSTs; the Commonwealth cluster is also found in the MSTs. By studying four evaluation criteria, we find that the MSTs of the FX market present diverse topological and statistical properties at different time scales. The scale-free behavior is observed in the FX network at most of time scales. We also find that most of links in the FX network survive from one time scale to the next.
Energy Technology Data Exchange (ETDEWEB)
Endo, Akira; Takada, Hiroshi; Yamaguchi, Yasuhiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1997-10-01
Dose coefficients have been calculated for inhalation of radionuclides generated in spallation neutron targets and not listed in ICRP Publication 68. Eleven radionuclides, generated in large quantities in the targets and having half-lives more than 10 minutes, were selected for the present calculation. The calculation of the dose coefficients was performed with LUDEP, a program implementing the ICRP Publication 66 respiratory tract model, and NUDAT, a decay radiation database processed from ENSDF. Comparisons were made between the dose coefficients calculated by LUDEP and those listed in ICRP Publication 68 in order to validate the calculated dose coefficients. For 228 cases that vary inhaled particle diameters and biokinetic models of 66 radionuclides, the dose coefficients calculated by LUDEP agreed with those of ICRP Publication 68 within {+-} 25% for 213 cases. Discrepancies that exceed the ICRP`s coefficients by {+-} 25% were mainly attributable to the difference of radiation data employed. It was confirmed from the comparisons that the dose coefficients calculated by the present method are reliable ones. Annual limits on intake and derived air concentrations were calculated on the basis of the dose coefficients. It can be concluded that the dose coefficients and limits calculated here are useful from viewpoints of the design of ventilation system and the evaluation of internal exposures in high energy proton accelerator facilities. (author)
Ochoa, O.; Jiang, J.; Putnam, D.; Lo, Z.; Ellis, A.; Effinger, Michael
2003-01-01
The transverse coefficient of thermal expansion (CTE) of single IM7, T1000, and P55 carbon fibers are measured at elevated temperatures. The specimens are prepared by press-fitting fiber tows into 0.7mm-diameter cavity in a graphite disk of 5mm in diameter and 3mm high. The specimens are placed on a crucible in an ESEM, and images of the fiber cross section are taken as the fibers are heated up to 800 C. Holding time, heating and cool down cycles are also introduced. The geometrical changes are measured using a graphics tablet. The change in area/perimeter is calculated to determine the strain and transverse CTE for each fiber. In a complimentary computational effort, displacements and stresses are calculated with finite element models.
Thompson, Stephen C; Markley, Douglas C
2013-01-01
Underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes, bonded together and electrically connected in parallel. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, stack segmentation has no significant effect on the mechanical behavior of the device. However, when a high coupling coefficient material such as PMN-PT is used to achieve a wider bandwidth, the difference between a segmented stack and a similar piezoelectric section with electrodes only at the two ends can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater acoustic transducers, particularly tonpilz transducer elements. Included is discussion of transduce...
Cao, Ning; Liang, Xuwei; Zhuang, Qi; Zhang, Jun
2009-02-01
Magnetic Resonance Imaging (MRI) techniques have achieved much importance in providing visual and quantitative information of human body. Diffusion MRI is the only non-invasive tool to obtain information of the neural fiber networks of the human brain. The traditional Diffusion Tensor Imaging (DTI) is only capable of characterizing Gaussian diffusion. High Angular Resolution Diffusion Imaging (HARDI) extends its ability to model more complex diffusion processes. Spherical harmonic series truncated to a certain degree is used in recent studies to describe the measured non-Gaussian Apparent Diffusion Coefficient (ADC) profile. In this study, we use the sampling theorem on band-limited spherical harmonics to choose a suitable degree to truncate the spherical harmonic series in the sense of Signal-to-Noise Ratio (SNR), and use Monte Carlo integration to compute the spherical harmonic transform of human brain data obtained from icosahedral schema.
Lee, JeongYub; Song, Byonggwon; Kim, Jaekwan; Lee, Chang-Won; Han, Seunghoon; Baik, Chan-Wook; Jeong, Heejeong; Kim, Yongsung; Lee, Chang Seung
2016-09-01
We investigated forming of high refractive index (n), low extinction coefficient (k) of Si dielectrics in visible wavelength ranges. To decrease k, pulsed green laser annealing (GLA) with line beam of a 532-nm wavelength was applied in this study for homogeneous melting. By AFM, XRD and TEM analysis, we examined the defect reduction in various conditions during poly-crystallization. We achieved dielectric nanostructures having optical properties of n>4.2, k<0.06 at 550 nm wavelength and fine pitches down to 40 nm (aspect ratio 3:1) and 130 nm (aspect ratio 7:1) with +/-5% size accuracy. Finally, we realized optical metasurfaces for optical band filters, flat lens and beam deflectors.
Zhong, Changjian; Gao, Jianrong; Cui, Yanhong; Li, Ting; Han, Liang
2015-01-01
Coumarin unit is introduced into triarylamine and three organic sensitizers are designed and synthesized with triarylamine bearing coumarin moiety as the electron donor, conjugated system containing thiophene unit as the π-bridge, and cyanoacetic acid moiety as the electron acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes are investigated systematically with the comparison of different π-bridges. High molar extinction coefficients are observed in these triarylamine dyes and the photocurrent and photovoltage are increased with the introduction of another thiophene or benzene. Optimal photovoltaic performance (η = 6.24%, Voc = 690 mV, Jsc = 14.33 mA cm-2, and ff = 0.63) is observed in the DSSC based on dye with thiophene-phenyl unit as the π-conjugated bridge under 100 mW cm-2 simulated AM 1.5 G solar irradiation.
High-fidelity coding with correlated neurons.
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Rava Azeredo da Silveira
2014-11-01
Full Text Available Positive correlations in the activity of neurons are widely observed in the brain. Previous studies have shown these correlations to be detrimental to the fidelity of population codes, or at best marginally favorable compared to independent codes. Here, we show that positive correlations can enhance coding performance by astronomical factors. Specifically, the probability of discrimination error can be suppressed by many orders of magnitude. Likewise, the number of stimuli encoded--the capacity--can be enhanced more than tenfold. These effects do not necessitate unrealistic correlation values, and can occur for populations with a few tens of neurons. We further show that both effects benefit from heterogeneity commonly seen in population activity. Error suppression and capacity enhancement rest upon a pattern of correlation. Tuning of one or several effective parameters can yield a limit of perfect coding: the corresponding pattern of positive correlation leads to a 'lock-in' of response probabilities that eliminates variability in the subspace relevant for stimulus discrimination. We discuss the nature of this pattern and we suggest experimental tests to identify it.
Indian Academy of Sciences (India)
Wen Yan; Junfeng Chen; Nan Li; BingqiangHan Han; Yaowu Wei
2015-04-01
Lightweight cordierite–mullite refractories with low coefficients of thermal conductivity (CTCs), high strengths and high thermal-shock resistances were prepared using porous cordierite ceramics as aggregates. Phase compositions and microstructures of lightweight refractories were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), etc. The effect of the relative mullite content of matrix (RMCM) on the microstructures and properties of lightweight refractories was investigated. It was found that the RMCM has a strong effect on the CTC and the mechanical properties. With an increase of RMCM, the compressive and flexural strengths of specimen increase. The thermal-shock resistance is the highest when the RMCM is 22 wt%, and also improved slightly when the RMCM is 46 wt% comparing with the specimen without mullite. When the RMCM is 46 wt%, the CTC reaches the minimum. Specimen with the RMCM of 46 wt% is the most appropriate mode, which has a moderate apparent porosity of 30%, a high compressive strength of 135.1 MPa, a high flexural strength of 20.5 MPa, a good thermal-shock resistance and a low CTC of 0.61 W mK−1.
Carbonation Coefficients from Concrete Made with High-Absorption Limestone Aggregate
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Eric I. Moreno
2013-01-01
Full Text Available Normal aggregates employed in concrete have absorption levels in the range of 0.2% to 4% for coarse aggregate and 0.2 to 2% for fine aggregate. However, some aggregates have absorption levels above these values. As the porosity of concrete is related to the porosity of both the cement paste and the aggregate and the carbonation rate is a function, among other things, of the porosity of the material, there is concern about the effect of this high porosity material in achieving good quality concrete from the durability point of view. Thus, the objective of this investigation was to study the carbonation rates of concrete specimens made with high-absorption limestone aggregate. Four different water/cement ratios were used, and cylindrical concrete specimens were exposed to accelerated carbonation. High porosity values were obtained for concrete specimens beyond the expected limits for durable concrete. However, carbonation coefficients related to normal quality concrete were obtained for the lowest water/cement ratio employed suggesting that durable concrete may be obtained with this material despite the high porosity.
Shih, I-Lun; Yen, Ruoh-Fang; Chen, Chi-An; Chen, Bang-Bin; Wei, Shwu-Yuan; Chang, Wen-Chun; Sheu, Bor-Ching; Cheng, Wen-Fang; Tseng, Yao-Hui; Chen, Xin-Jia; Chen, Chi-Hau; Wei, Lin-Hung; Chiang, Ying-Cheng; Torng, Pao-Ling; Yen, Men-Luh; Shih, Tiffany Ting-Fang
2015-12-01
To evaluate the correlation between maximum standardized uptake value (SUVmax ) and minimum apparent diffusion coefficient (ADCmin ) of endometrial cancer derived from an integrated positron emission tomography / magnetic resonance (PET/MR) system and to determine their correlation with pathological prognostic factors. This prospective study was approved by the Institutional Review Board of the hospital, and informed consent was obtained. Between April and December 2014, 47 consecutive patients with endometrial cancer were enrolled and underwent simultaneous PET/MR examinations before surgery. Thirty-six patients with measurable tumors on PET/MR were included for image analysis. Pearson's correlation coefficient was used to evaluate the correlation between SUVmax and ADCmin of the tumors. The Mann-Whitney U-test was utilized to evaluate relationships between these two imaging biomarkers and pathological prognostic factors. The mean SUVmax and ADCmin were 14.7 ± 7.1 and 0.48 ± 0.13 × 10(-3) mm(2) /s, respectively. A significant inverse correlation was found between SUVmax and ADCmin (r = -0.53; P = 0.001). SUVmax was significantly higher in tumors with advanced stage, deep myometrial invasion, cervical invasion, lymphovascular space involvement, and lymph node metastasis (P correlated and are associated with pathological prognostic factors. © 2015 Wiley Periodicals, Inc.
Consalvi, J. L.; Nmira, F.
2016-03-01
The main objective of this article is to quantify the influence of the soot absorption coefficient-Planck function correlation on radiative loss and flame structure in an oxygen-enhanced propane turbulent diffusion flame. Calculations were run with and without accounting for this correlation by using a standard k-ε model and the steady laminar flamelet model (SLF) coupled to a joint Probability Density Function (PDF) of mixture fraction, enthalpy defect, scalar dissipation rate, and soot quantities. The PDF transport equation is solved by using a Stochastic Eulerian Field (SEF) method. The modeling of soot production is carried out by using a flamelet-based semi-empirical acetylene/benzene soot model. Radiative heat transfer is modeled by using a wide band correlated-k model and turbulent radiation interactions (TRI) are accounted for by using the Optically-Thin Fluctuation Approximation (OTFA). Predicted soot volume fraction, radiant wall heat flux distribution and radiant fraction are in good agreement with the available experimental data. Model results show that soot absorption coefficient and Planck function are negatively correlated in the region of intense soot emission. Neglecting this correlation is found to increase significantly the radiative loss leading to a substantial impact on flame structure in terms of mean and rms values of temperature. In addition mean and rms values of soot volume fraction are found to be less sensitive to the correlation than temperature since soot formation occurs mainly in a region where its influence is low.
Directory of Open Access Journals (Sweden)
Heethal Jaiprakash
2016-03-01
Full Text Available This paper is aimed at finding if there was a change of correlation between the written test score and tutors’ performance test scores in the assessment of medical students during a problem-based learning (PBL course in Malaysia. This is a cross-sectional observational study, conducted among 264 medical students in two groups from November 2010 to November 2012. The first group’s tutors did not receive tutor training; while the second group’s tutors were trained in the PBL process. Each group was divided into high, middle and low achievers based on their end-of-semester exam scores. PBL scores were taken which included written test scores and tutors’ performance test scores. Pearson correlation coefficient was calculated between the two kinds of scores in each group. The correlation coefficient between the written scores and tutors’ scores in group 1 was 0.099 (p<0.001 and for group 2 was 0.305 (p<0.001. The higher correlation coefficient in the group where tutors received the PBL training reinforces the importance of tutor training before their participation in the PBL course.
DEFF Research Database (Denmark)
Larsen, Thomas; Kjeldsen, Peter; Christensen, Thomas Højlund
1992-01-01
area of the aquifer materials as a second regression parameter did not significantly improve the correlation. Estimated Koc values were up to 3 times higher than those predicted from regression equations based on the octanol-water partition coefficient. The reason for this is not known, but may...... by the distribution coefficient, Kd, since the isotherms were linear: Kd(benzene): 0.05–0.65, Kd(TCA): 0.04–0.55, and Kd(naphthalene): 0.1–15.7 ml/g. Correlating observed Kd values to the organic carbon content of the aquifer materials explained only 52–65 % of the variance in Kd. Introducing the specific surface...
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Yongbin Liu
2017-01-01
Full Text Available Envelope spectrum analysis is a simple, effective, and classic method for bearing fault identification. However, in the wayside acoustic health monitoring system, owing to the high relative moving speed between the railway vehicle and the wayside mounted microphone, the recorded signal is embedded with Doppler effect, which brings in shift and expansion of the bearing fault characteristic frequency (FCF. What is more, the background noise is relatively heavy, which makes it difficult to identify the FCF. To solve the two problems, this study introduces solutions for the wayside acoustic fault diagnosis of train bearing based on Doppler effect reduction using the improved time-domain interpolation resampling (TIR method and diagnosis-relevant information enhancement using Weighted-Correlation-Coefficient-Guided Stochastic Resonance (WCCSR method. First, the traditional TIR method is improved by incorporating the original method with kinematic parameter estimation based on time-frequency analysis and curve fitting. Based on the estimated parameters, the Doppler effect is removed using the TIR easily. Second, WCCSR is employed to enhance the diagnosis-relevant period signal component in the obtained Doppler-free signal. Finally, paved with the above two procedures, the local fault is identified using envelope spectrum analysis. Simulated and experimental cases have verified the effectiveness of the proposed method.
Anigbogu, Chikodi N; Williams, Daniel T; Brown, David R; Silcox, Dennis L; Speakman, Richard O; Brown, Laura C; Karounos, Dennis G; Randall, David C
2011-01-01
Circadian changes in cardiovascular function during the progression of diabetes mellitus in the diabetes prone rat (BBDP) (n = 8) were studied. Age-matched diabetes-resistant rats (BBDR) served as controls. BP was recorded via telemetry in contiguous 4 hr time periods over 24 hours starting with 12 midnight to 4 am as period zero (P0). Prior to onset of diabetes BP was high at P0, peaked at P2, and then fell again at P3; BP and heart rate (HR) then increased gradually at P4 and leveled off at P5, thereby exhibiting a bipodal rhythm. These patterns changed during long-term diabetes. The cross-correlation coefficient of BP and HR was not significantly different across groups at onset, but it fell significantly at 9 months of duration of diabetes (BBDP: 0.39 ± 0.06; BBDR: 0.65 ± 0.03; P < .05). These results show that changes in circadian cardiovascular rhythms in diabetes mellitus became significant at the late stage of the disease.
Energy Technology Data Exchange (ETDEWEB)
Inchingolo, Riccardo; De Gaetano, Anna Maria; Curione, Davide; Ciresa, Marzia; Bonomo, Lorenzo [Catholic University of the Sacred Heart, Department of Bioimaging and Radiological Sciences, Institute of Radiology, ' ' Agostino Gemelli' ' Hospital, Rome (Italy); Miele, Luca; Pompili, Maurizio [Catholic University of the Sacred Heart, Department of Internal Medicine, ' ' Agostino Gemelli' ' Hospital, Rome (Italy); Vecchio, Fabio Maria [Catholic University of the Sacred Heart, Department of Anatomo-Pathology, ' ' Agostino Gemelli' ' Hospital, Rome (Italy); Giuliante, Felice [Catholic University of the Sacred Heart, Department of Surgery, ' ' Agostino Gemelli' ' Hospital, Rome (Italy)
2015-04-01
To investigate the utility of diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and the correlation with hepatobiliary phase (delayed phase imaging, DPI) findings in the differentiation of cirrhotic hepatocellular nodules. Forty-three patients with 53 pathology-proven nodules (29 hepatocellular carcinomas (HCCs), 13 high-grade (HGDNs) and 11 low-grade dysplastic nodules (LGDNs); mean size 2.17 cm, range 1-4 cm), who underwent liver MRI with DWI and DPI sequences, were retrospectively reviewed. Lesions were classified as hypointense, isointense, or hyperintense relative to the adjacent liver parenchyma. ADC of each nodule, of the surrounding parenchyma, and lesion-to-liver ratio were calculated. Hyperintensity versus iso/hypointensity on DWI, hypointensity versus iso/hyperintensity on DPI, and the mean lesion-to-liver ratio showed a statistically significant difference both between HCCs versus DNs and between ''HCCs + HGDNs'' versus LGDNs (p < 0.05); sensitivity, specificity, and accuracy for the diagnosis of ''HCCs + HGDNs'' were 96.8 %, 100 %, 97.4 % respectively when combining hyperintensity on DWI and hypointensity on DPI, and 90.9 %, 81.0 %, 83.6 % respectively when lesion-to-liver ratio was <0.95. Hyperintensity on DWI, especially in association with hypointensity on DPI, and low lesion-to-liver ratios should raise the suspicion of HCC, or at least of HGDN, thus helping the characterization of atypically enhancing lesions. (orig.)
Green's function formalism for highly correlated systems
Directory of Open Access Journals (Sweden)
F.Mancini
2006-01-01
Full Text Available We present the Composite Operator Method (COM as a modern approach to the study of strongly correlated electronic systems, based on the equation of motion and Green's function method. COM uses propagators of composite operators as building blocks at the basis of approximate calculations and algebra constrains to fix the representation of Green's functions in order to maintain the algebraic and symmetry properties.
Woo, Sungmin; Cho, Jeong Yeon; Kim, Sang Youn; Kim, Seung Hyup
2014-12-01
Until now, several investigators have explored the value of diffusion-weighted magnetic resonance imaging (DWI) for the preoperative tumor grading of endometrial cancer. However, the diagnostic value of DWI with quantitative analysis of apparent diffusion coefficient (ADC) has been controversial. To explore the role of histogram analysis of ADC maps based on entire tumor volume in determining the grade of endometrial cancer. This study was IRB-approved with waiver of informed consent. Thirty-three patients with endometrial cancer underwent DWI (b = 0, 600, 1000 s/mm(2)), and corresponding ADC maps were acquired. Regions of interest (ROIs) were drawn on all slices of the ADC map in which the tumor was visualized including areas of necrosis to derive volume-based histographic ADC data. Histogram parameters (5th-95th percentiles, mean, standard deviation, skewness, kurtosis) were correlated with histological grade using one-way ANOVA with Tukey-Kramer test for post hoc comparisons, and were compared between high (grade 3) and low (grades 1/2) grade using Student t-test. ROC curve analysis was performed to determine the optimum threshold value for each parameter, and their corresponding sensitivity and specificity. The standard deviation, quartile, 75th, 90th, and 95th percentiles of ADC showed significant differences between grades (P ≤ 0.03 for all) and between high and low grades (P ≤ 0.024 for all). There were no significant correlations between tumor grade and other parameters. ROC curve analysis yielded sensitivities and specificities of 75% and 96%, 62.5% and 92%, 100% and 52%, 100% and 72%, and 100% and 88%, using standard deviation, quartile, 75th, 90th, and 95th percentiles for determining high grade with corresponding areas under the curve (AUCs) of 0.787, 0.792, 0.765, 0.880, and 0.925, respectively. Histogram analysis of ADC maps based on entire tumor volume can be useful for predicting the histological grade of endometrial cancer. The 90th and 95th
Mahdi Alajmi; Abdullah Shalwan
2015-01-01
The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE), Graphite/Epoxy composites (GE), and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE). The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific...
Othman, N.; Shah, N. S. M.; Tay, K. G.; Pakarzadeh, H.; Cholan, N. A.; Talib, R.
2017-09-01
The highly-nonlinear fiber is the ideal gain medium for many applications particularly because its dispersion can be easily engineered. However, the modification of the fiber dispersion will affect the higher-order dispersion coefficients. Hence, this paper investigates the effect of highly-nonlinear dispersion-shifted fiber dispersion profile on the higher-order dispersion coefficients which are the fourth-order and sixth-order dispersion coefficients. The dispersion profile was modified by varying the slope at zero-dispersion wavelength. The fourth-order dispersion coefficient exhibits changes from positive to negative value as the slope at zero-dispersion wavelength is getting higher. Meanwhile, sixth-order dispersion coefficient remains with the positive value even though it shows the reduction as the slope is increased, however it will eventually become negative when the dispersion is high enough. In short, the values of both fourth-order and sixth-order dispersion coefficients at zero-dispersion wavelength decrease when the slope increases.
Jaiprakash, Heethal; Min, Aung Ko Ko; Ghosh, Sarmishtha
2016-03-01
This paper is aimed at finding if there was a change of correlation between the written test score and tutors' performance test scores in the assessment of medical students during a problem-based learning (PBL) course in Malaysia. This is a cross-sectional observational study, conducted among 264 medical students in two groups from November 2010 to November 2012. The first group's tutors did not receive tutor training; while the second group's tutors were trained in the PBL process. Each group was divided into high, middle and low achievers based on their end-of-semester exam scores. PBL scores were taken which included written test scores and tutors' performance test scores. Pearson correlation coefficient was calculated between the two kinds of scores in each group. The correlation coefficient between the written scores and tutors' scores in group 1 was 0.099 (pcorrelation coefficient in the group where tutors received the PBL training reinforces the importance of tutor training before their participation in the PBL course.
Institute of Scientific and Technical Information of China (English)
王凯; 冯晅; 刘财
2012-01-01
横波分裂是各向异性介质的重要特征,当横波或转换波穿过各向异性介质到达地面时,地面三分量检波器的x分量和y分量接收到的地震记录中都会同时存在快横波和慢横波.将快横波和慢横波进行分离,进而计算介质的各向异性参数是多分量数据处理中重要的一步.将数学中的Pearson相关系数引入到多分量地震勘探中,提出了Pearson相关系数法进行旋转角度识别,进而分离快、慢横波波场.相比于传统的互相关法,Pearson相关系数法从精度、抗噪性能和计算效率上都有提高.%Shear-wave splitting is an important characteristic of anisotropic media. Generally, when S or P-SV waves reach to the ground through anisotropic media, the seismic record received by x component and y component of three-component detector contains fast wave and slow wave simultaneously- Separating fast wave and slow wave and then calculating the anisotropic parameters of media are an important step in multi-component data processing. The authors introduce the Pearson correlation coefficients into multi-component seismic exploration and propose the Pearson correlation coefficients to detect the rotation angle and then separate the fast wave and slow wave. Compared with the traditional cross-correlation method, the Pearson correlation coefficient method is better in accuracy, noise immunity and computational efficiency.
High-order correlation of chaotic bosons and fermions
Liu, Hong-Chao
2016-08-01
We theoretically study the high-order correlation functions of chaotic bosons and fermions. Based on the different parity of the Stirling number, the products of the first-order correlation functions are well classified and employed to represent the high-order correlation function. The correlation of bosons conduces a bunching effect, which will be enhanced as order N increases. Different from bosons, the anticommutation relation of fermions leads to the parity of the Stirling number, which thereby results in a mixture of bunching and antibunching behaviors in high-order correlation. By further investigating third-order ghost diffraction and ghost imaging, the differences between the high-order correlations of bosons and fermions are discussed in detail. A larger N will dramatically improve the ghost image quality for bosons, but a good strategy should be carefully chosen for the fermionic ghost imaging process due to its complex correlation components.
DEFF Research Database (Denmark)
Christensen, Eva Arnspang; Koffman, Jennifer Skaarup; Marlar, Saw
2014-01-01
Lateral diffusion and compartmentalization of plasma membrane proteins are tightly regulated in cells and thus, studying these processes will reveal new insights to plasma membrane protein function and regulation. Recently, k-Space Image Correlation Spectroscopy (kICS)1 was developed to enable ro...
Energy Technology Data Exchange (ETDEWEB)
Biyikli, Suleyman [Okan University Tuzla Kampusu, Faculty of Engineering and Architecture (Turkey)], email: suleyman.biyikli@okan.edu.tr
2011-07-01
This article investigates the heat transfer characteristics for horizontal tubes in a freeboard region of high temperature fluidized beds. The freeboard entrainment heights are calculated by using empirical correlations described in detail and used in estimating the heat transfer coefficients from a horizontal tube occurring by radiation, gas convection, and particle contact mechanisms in high temperature a fluidized bed combustor. The total average of these coefficients around a horizontal tube carrying water in high temperature fluidized beds can be written as the sum of convective, radiative, and fluidized-particle contact heat transfer coefficients and these correlations are tested against certain published experimental measurements. In full agreement with this data, it was observed that the calculated heat transfer coefficients increased with increasing gas velocity at a given tube elevation and they decreased and approached the values of single-phase gas convection and radiation with increasing tube elevation in the freeboard region while the relative contribution of radiation increases and approaches a constant fraction of total heat transfer.
Multilevel Methods for Elliptic Problems with Highly Varying Coefficients on Nonaligned Coarse Grids
Energy Technology Data Exchange (ETDEWEB)
Scheichl, Robert [Univ. of Bath (United Kingdom). Dept. of Mathematical Sciences; Vassilevski, Panayot S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zikatanov, Ludmil T. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mathematics
2012-06-21
We generalize the analysis of classical multigrid and two-level overlapping Schwarz methods for 2nd order elliptic boundary value problems to problems with large discontinuities in the coefficients that are not resolved by the coarse grids or the subdomain partition. The theoretical results provide a recipe for designing hierarchies of standard piecewise linear coarse spaces such that the multigrid convergence rate and the condition number of the Schwarz preconditioned system do not depend on the coefficient variation or on any mesh parameters. One assumption we have to make is that the coarse grids are sufficiently fine in the vicinity of cross points or where regions with large diffusion coefficients are separated by a narrow region where the coefficient is small. We do not need to align them with possible discontinuities in the coefficients. The proofs make use of novel stable splittings based on weighted quasi-interpolants and weighted Poincaré-type inequalities. Finally, numerical experiments are included that illustrate the sharpness of the theoretical bounds and the necessity of the technical assumptions.
Cross-correlations in high-conductance states of a model cortical network
DEFF Research Database (Denmark)
Hertz, John
2010-01-01
(dansk abstrakt findes ikke) Neuronal firing correlations are studied using simulations of a simple network model for a cortical column in a high-conductance state with dynamically balanced excitation and inhibition. Although correlations between individual pairs of neurons exhibit considerable...... heterogeneity, population averages show systematic behavior. When the network is in a stationary state, the average correlations are generically small: correlation coefficients are of order 1/N, where N is the number of neurons in the network. However, when the input to the network varies strongly in time, much...... larger values are found. In this situation, the network is out of balance, and the synaptic conductance is low, at times when the strongest firing occurs. However, examination of the correlation functions of synaptic currents reveals that after these bursts, balance is restored within a few ms...
Afacan, Onur; Gholipour, Ali; Mulkern, Robert V; Barnewolt, Carol E; Estroff, Judy A; Connolly, Susan A; Parad, Richard B; Bairdain, Sigrid; Warfield, Simon K
2016-12-01
To evaluate the feasibility of using diffusion-weighted magnetic resonance imaging (DW-MRI) to assess the fetal lung apparent diffusion coefficient (ADC) at 3 Tesla (T). Seventy-one pregnant women (32 second trimester, 39 third trimester) were scanned with a twice-refocused Echo-planar diffusion-weighted imaging sequence with 6 different b-values in 3 orthogonal diffusion orientations at 3T. After each scan, a region-of-interest (ROI) mask was drawn to select a region in the fetal lung and an automated robust maximum likelihood estimation algorithm was used to compute the ADC parameter. The amount of motion in each scan was visually rated. When scans with unacceptable levels of motion were eliminated, the lung ADC values showed a strong association with gestational age (P < 0.01), increasing dramatically between 16 and 27 weeks and then achieving a plateau around 27 weeks. We show that to get reliable estimates of ADC values of fetal lungs, a multiple b-value acquisition, where motion is either corrected or considered, can be performed. J. Magn. Reson. Imaging 2016;44:1650-1655. © 2016 International Society for Magnetic Resonance in Medicine.
Measurement of the Ar diffusion coefficient in graphite at high temperature by the ISOL method
Energy Technology Data Exchange (ETDEWEB)
Eleon, C. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France); Jardin, P. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France)], E-mail: Jardin@ganil.fr; Thomas, J.C.; Saint-Laurent, M.-G.; Huet-Equilbec, C.; Alves Conde, R. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France); Angelique, J.C. [Laboratoire de Physique Subatomique et de Cosmologie, 38026 Grenoble (France); Laboratoire de Physique Corpusculaire, ISMRA, 14050 Caen (France); Boilley, D.; Cornell, J.; Dubois, M. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France); Franberg, H. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); ISOLDE, CERN, 1211 Geneve 23 (Switzerland); Gaubert, G.; Jacquot, B. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France); Koester, U. [ISOLDE, CERN, 1211 Geneve 23 (Switzerland); Institut Laue Langevin, 38042 Grenoble (France); Leroy, R. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France); Maunoury, L. [Centre Interdisciplinaire de Recherche Ion Laser, 14070 Caen (France); Orr, N. [Laboratoire de Physique Corpusculaire, ISMRA, 14050 Caen (France); Pacquet, J.Y.; Pellemoine, F.; Stodel, C. [Grand Accelerateur National d' Ions Lourds, CEA/DSM CNRS/IN2P3, 14076 Caen (France)] (and others)
2008-10-15
This work has been carried out at GANIL within the ambit of the TARGISOL European collaboration which aims to study the relevant variables governing the release of radioactive elements from targets in an ISOL system. This work shows how it has been possible to extract diffusion coefficients for {sup 35}Ar atoms diffusing out of graphite targets from release time measurements by using an analytic description of the release times. The diffusion coefficients and efficiencies are presented and compared with results obtained using a 'continuous' method.
Fluctuations and correlations in high temperature QCD
Bellwied, R; Fodor, Z; Katz, S D; Pasztor, A; Ratti, C; Szabo, K K
2015-01-01
We calculate second- and fourth-order cumulants of conserved charges in a temperature range stretching from the QCD transition region towards the realm of (resummed) perturbation theory. We perform lattice simulations with staggered quarks; the continuum extrapolation is based on $N_t=10\\dots24$ in the crossover-region and $N_t=8\\dots16$ at higher temperatures. We find that the Hadron Resonance Gas model predictions describe the lattice data rather well in the confined phase. At high temperatures (above $\\sim$250 MeV) we find agreement with the three-loop Hard Thermal Loop results.
Rakheja, Rajan; Chandarana, Hersh; DeMello, Linda; Jackson, Kimberly; Geppert, Christian; Faul, David; Glielmi, Christopher; Friedman, Kent P
2013-11-01
The purpose of this study was to assess the correlation between standardized uptake value (SUV) and apparent diffusion coefficient (ADC) of neoplastic lesions in the use of a simultaneous PET/MRI hybrid system. Twenty-four patients with known primary malignancies underwent FDG PET/CT. They then underwent whole-body PET/MRI. Diffusion-weighted imaging was performed with free breathing and a single-shot spin-echo echo-planar imaging sequence with b values of 0, 350, and 750 s/mm(2). Regions of interest were manually drawn along the contours of neoplastic lesions larger than 1 cm, which were clearly identified on PET and diffusion-weighted images. Maximum SUV (SUVmax) on PET/MRI and PET/CT images, mean SUV (SUVmean), minimum ADC (ADCmin), and mean ADC (ADCmean) were recorded on PET/MR images for each FDG-avid neoplastic soft-tissue lesion with a maximum of three lesions per patient. Pearson correlation coefficient was used to asses the following relations: SUVmax versus ADCmin on PET/MR and PET/CT images, SUVmean versus ADCmean, and ratio of SUVmax to mean liver SUV (SUV ratio) versus ADCmin. A subanalysis of patients with progressive disease versus partial treatment response was performed with the ratio of SUVmax to ADCmin for the most metabolically active lesion. Sixty-nine neoplastic lesions (52 nonosseous lesions, 17 bone metastatic lesions) were evaluated. The mean SUVmax from PET/MRI was 7.0 ± 6.0; SUVmean, 5.6 ± 4.6; mean ADCmin, 1.10 ± 0.58; and mean ADCmean, 1.48 ± 0.72. A significant inverse Pearson correlation coefficient was found between PET/MRI SUVmax and ADCmin (r = -0.21, p = 0.04), between SUVmean and ADCmean (r = -0.18, p = 0.07), and between SUV ratio and ADCmin (r = -0.27, p = 0.01). A similar inverse Pearson correlation coefficient was found between the PET/CT SUVmax and ADCmin. Twenty of 24 patients had previously undergone PET/CT; five patients had a partial treatment response, and six had progressive disease according to Response Evaluation
Energy Technology Data Exchange (ETDEWEB)
Petzoldt, G.
2007-08-29
In the four beam times we performed at the FRM-II, we were able to show that the spectrometer works in principle and that a determination of a with it is possible. A set of routines has been written for decoding and analyzing the raw data. The routines are written in C using the ROOT libraries and can be easily adapted or expanded. We have found a reliable way to extract the proton count rates from the data by building pulseheight spectra for each measurement, subtracting background measurements from those and fitting the resulting peak with a Gaussian. The background of the measurements was studied in detail. The background caused by electrons from neutron decay is very well understood and conforms quantitatively to our expectation. Due to the spatial resolution of our detector and the time resolution provided by our DAQ electronics, we were able to study correlated electron-proton pairs from one neutron decay event. They form a clearly visible peak in a time- and channel-distance spectrum, which can be shifted in the channel-dimension by varying the voltages applied to the lower and upper E x B electrodes. Performing a pulseheight analysis for both involved particles allowed us to obtain a fairly clean energy spectrum of the background caused by electrons from neutron decay in our detector. Using these correlations for data analysis may be of interest for future neutron decay experiments which use segmented detectors. (orig.)
Strength and Biot's coefficient for high-porosity oil- or water-saturated chalk
DEFF Research Database (Denmark)
Andreassen, Katrine Alling
considerations for the size of the drilling window and the magnitude of the lateral stress involve the Biot coefficient. Additionally, the fluid effect of oil-saturated chalk behaving much stronger than water-saturated chalk affects geomechanical considerations related to e.g. water injection into a reservoir...
Static Coefficient of Rolling Friction at High Contact Temperatures and Various Contact Pressure
Directory of Open Access Journals (Sweden)
B. Tadić
2016-03-01
Full Text Available The paper theoretically and experimentally analyzes the influence of increased temperature and load contact in the value of the coefficient of rolling friction. Theoretical analyzes show that at temperatures of the order of 200 0C, exist thermal potential necessary to narrow contact zone leads to a redistribution of the contact pressure and an increase in torque performance. Based on the measurement results, established the regression coefficient of friction depending on the temperature, normal load and geometry parameters of contact elements (radius of curvature of the contact elements. Material of examination contact pairs is steel ASTM A-295 hardness 64-66 HRC. The measurement results indicate a very significant impact on the temperature coefficient of friction, normal load and contact geometry (the radius of curvature of the contact elements. According to the authors future research should focus on optimizing the choice of materials that under the given conditions of mechanical and thermal load of contact to ensure a minimum value of the coefficient of rolling friction.
Institute of Scientific and Technical Information of China (English)
OU Xiaojuan; ZHOU Wei
2007-01-01
Global positioning system (GPS)common-view observation data were processed by using the multi-scale Kalman algorithm based on a correlative structure of the discrete wavelet coefficients.Suppose that the GPS common-view observation data has the 1/f fractal characteristic,the algorithm of wavelet transform was used to estimate the Hurst parameter H of GPS clock difference data.When 0＜H＜1,the 1/f fractal characteristic of the GPS clock difference data iS a Gaussian zero-mean and non-stationary stochastic process.Thus,the discrete wavelet coefficients can be discussed in the process of estimating multi-scale Kalman coefficients.Furthermore,the discrete clock difierence can be estimated.The single-channel and multi-channel common-view observation data were processed respectively.Comparisons were made between the results obtained and the Circular T data.Simulation results show that the algorithm discussed in this paper is both feasible and effective.
Guo, Yuan; Kong, Qing-Cong; Zhu, Ye-Qing; Liu, Zhen-Zhen; Peng, Ling-Rong; Tang, Wen-Jie; Yang, Rui-Meng; Xie, Jia-Jun; Liu, Chun-Ling
2017-06-22
To evaluate the utility of the whole-lesion histogram apparent diffusion coefficient (ADC) for characterizing the heterogeneity of mucinous breast carcinoma (MBC) and to determine which ADC metrics may help to best differentiate subtypes of MBC. This retrospective study involved 52 MBC patients, including 37 pure MBC (PMBC) and 15 mixed MBC (MMBC). The PMBC patients were subtyped into PMBC-A (20 cases) and PMBC-B (17 cases) groups. All patients underwent preoperative diffusion-weighted imaging (DWI) at 1.5T and the whole-lesion ADC assessments were generated. Histogram-derived ADC parameters were compared between PMBC vs. MMBC and PMBC-A vs. PMBC-B, and receiver operating characteristic (ROC) curve analysis was used to determine optimal histogram parameters for differentiating these groups. The PMBC group exhibited significantly higher ADC values for the mean (P = 0.004), 25(th) (P = 0.004), 50(th) (P = 0.004), 75(th) (P = 0.006), and 90(th) percentiles (P = 0.013) and skewness (P = 0.021) than did the MMBC group. The 25(th) percentile of ADC values achieved the highest area under the curve (AUC) (0.792), with a cutoff value of 1.345 × 10(-3) mm(2) /s, in distinguishing PMBC and MMBC. The PMBC-A group showed significantly higher ADC values for the mean (P = 0.049), 25(th) (P = 0.015), and 50(th) (P = 0.026) percentiles and skewness (P = 0.004) than did the PMBC-B group. The 25(th) percentile of the ADC cutoff value (1.476 × 10(-3) mm(2) /s) demonstrated the best AUC (0.837) among the ADC values for distinguishing PMBC-A and PMBC-B. Whole-lesion ADC histogram analysis enables comprehensive evaluation of an MBC in its entirety and differentiating subtypes of MBC. Thus, it may be a helpful and supportive tool for conventional MRI. 4 TECHNICAL EFFICACY: Stage 2 J. Magn. Reson. Imaging 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Sun, Yangbo; Chen, Long; Huang, Bisheng; Chen, Keli
2017-07-01
As a mineral, the traditional Chinese medicine calamine has a similar shape to many other minerals. Investigations of commercially available calamine samples have shown that there are many fake and inferior calamine goods sold on the market. The conventional identification method for calamine is complicated, therefore as a result of the large scale of calamine samples, a rapid identification method is needed. To establish a qualitative model using near-infrared (NIR) spectroscopy for rapid identification of various calamine samples, large quantities of calamine samples including crude products, counterfeits and processed products were collected and correctly identified using the physicochemical and powder X-ray diffraction method. The NIR spectroscopy method was used to analyze these samples by combining the multi-reference correlation coefficient (MRCC) method and the error back propagation artificial neural network algorithm (BP-ANN), so as to realize the qualitative identification of calamine samples. The accuracy rate of the model based on NIR and MRCC methods was 85%; in addition, the model, which took comprehensive multiple factors into consideration, can be used to identify crude calamine products, its counterfeits and processed products. Furthermore, by in-putting the correlation coefficients of multiple references as the spectral feature data of samples into BP-ANN, a BP-ANN model of qualitative identification was established, of which the accuracy rate was increased to 95%. The MRCC method can be used as a NIR-based method in the process of BP-ANN modeling.
Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure
Institute of Scientific and Technical Information of China (English)
Anting Wang(王安廷); Meishu Xing(邢美术); Guanghui Chen(陈光辉); Wenkui Yang(杨文奎); Hai Ming(明海); Jianping Xie(谢建平); Yunxia Wu(吴云霞)
2003-01-01
We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.
Cooper pair breaking and isotope effect coefficient variation in high-T{sub c} superconductors
Energy Technology Data Exchange (ETDEWEB)
Singh, S.P.; Pandey, R.K.; Singh, P. [G.B. Pant Univ. Pantanagar, Nainital (India)
1996-06-01
The effect of pair breaking on the isotope effect coefficient a = {minus}d ln T{sub c}/d ln M in La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and Pr-, Ca-, and Zn-doped YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} and EuBa{sub 2}Cu{sub 3}O{sub 7{minus}x} is studied using the generalized Abrikosov-Gorkov theory recently employed by Singh and Kishore for superconductivity. It is argued that the isotope effect coefficient a can be further enhanced, in agreement with experimental observation, by considering the dependence of the characteristic scattering time {tau}{sub s} for Cooper pairs on the concentration n of impurities (both magnetic and nonmagnetic) and the disorder ignored by them.
Mining Non-Redundant High Order Correlations in Binary Data.
Zhang, Xiang; Pan, Feng; Wang, Wei; Nobel, Andrew
2008-08-01
Many approaches have been proposed to find correlations in binary data. Usually, these methods focus on pair-wise correlations. In biology applications, it is important to find correlations that involve more than just two features. Moreover, a set of strongly correlated features should be non-redundant in the sense that the correlation is strong only when all the interacting features are considered together. Removing any feature will greatly reduce the correlation.In this paper, we explore the problem of finding non-redundant high order correlations in binary data. The high order correlations are formalized using multi-information, a generalization of pairwise mutual information. To reduce the redundancy, we require any subset of a strongly correlated feature subset to be weakly correlated. Such feature subsets are referred to as Non-redundant Interacting Feature Subsets (NIFS). Finding all NIFSs is computationally challenging, because in addition to enumerating feature combinations, we also need to check all their subsets for redundancy. We study several properties of NIFSs and show that these properties are useful in developing efficient algorithms. We further develop two sets of upper and lower bounds on the correlations, which can be incorporated in the algorithm to prune the search space. A simple and effective pruning strategy based on pair-wise mutual information is also developed to further prune the search space. The efficiency and effectiveness of our approach are demonstrated through extensive experiments on synthetic and real-life datasets.
Amiot, M N; Mesradi, M R; Chisté, V; Morin, M; Rigoulay, F
2012-09-01
The response of a Vacutec 70129 ionization chamber was calculated using the PENELOPE-2008 Monte Carlo code and compared to experimental data. The filling gas mixture composition and its pressure have been determined using IC simulated response adjustment to experimental results. The Monte Carlo simulation revealed a physical effect in the detector response to photons due to the presence of xenon in the chamber. A very good agreement is found between calculated and experimental calibration coefficients for 17 radionuclides.
DEFF Research Database (Denmark)
Poulios, Konstantinos; Svendsen, G.; Hiller, Jochen
2012-01-01
materials which are untypical for brake applications, like thermoplastics and fiber composites, can offer superior performance in terms of braking torque, wear resistance and cost than typical brake linings. In this paper coefficient of friction measurements for various thermoplastic and fiber composite...... materials running against a steel surface are presented. All tests were carried out on a pin-on-disc test-rig at a fixed sliding speed and various pressure levels for both dry and grease lubricated conditions....
Institute of Scientific and Technical Information of China (English)
Zongyao SUN; Yungang LIU
2007-01-01
In this paper, a new approach is successfully addressed to design the state-feedback adaptive stabilizing control law for a class of high-order nonlinear systems in triangular form and with unknown and nonidentical control coefficients, whose stabilizing control has been investigated recently under the knowledge that the lower bounds of the control coefficients are exactly known. In the present paper,without any knowledge of the lower bounds of the control coefficients, based on the adaptive technique and appropriately choosing design parameters, we give the recursive design procedure of the stabilizing control law by utilizing the approach of adding a power integrator together with tuning functions. The state-feedback adaptive control law designed not only preserves the equilibrium at the origin, but also guarantees the global asymptotic stability of the closed-loop states and the uniform boundedness of all the other closed-loop signals.
Cao, Yongyou; Guo, Zhipeng; Xiong, Shoumei
2012-07-01
High-pressure die cast B390 alloy was prepared on a 350 ton cold chamber die casting machine. The metal/die interfacial heat transfer coefficient of the alloy was investigated. Considering the filling process, a "finger"-shaped casting was designed for the experiments. This casting consisted of five plates with different thicknesses (0.05 inch or 1.27 mm to 0.25 inch or 6.35 mm) as well as individual ingates and overflows. Experiments under various operation conditions were conducted, and temperatures were measured at various specific locations inside the die. Based on the results, the interfacial heat transfer coefficient and heat flux were determined by solving the inverse heat transfer problem. The influence of the mold-filling sequence, sensor locations, as well as processing parameters including the casting pressure, die temperature, and fast/slow shot speeds on the heat transfer coefficient were discussed.
Chai, Bing-Bing; Vass, Jozsef; Zhuang, Xinhua
1997-04-01
Recent success in wavelet coding is mainly attributed to the recognition of importance of data organization. There has been several very competitive wavelet codecs developed, namely, Shapiro's Embedded Zerotree Wavelets (EZW), Servetto et. al.'s Morphological Representation of Wavelet Data (MRWD), and Said and Pearlman's Set Partitioning in Hierarchical Trees (SPIHT). In this paper, we propose a new image compression algorithm called Significant-Linked Connected Component Analysis (SLCCA) of wavelet coefficients. SLCCA exploits both within-subband clustering of significant coefficients and cross-subband dependency in significant fields. A so-called significant link between connected components is designed to reduce the positional overhead of MRWD. In addition, the significant coefficients' magnitude are encoded in bit plane order to match the probability model of the adaptive arithmetic coder. Experiments show that SLCCA outperforms both EZW and MRWD, and is tied with SPIHT. Furthermore, it is observed that SLCCA generally has the best performance on images with large portion of texture. When applied to fingerprint image compression, it outperforms FBI's wavelet scalar quantization by about 1 dB.
Turbulent transfer coefficient and roughness length in a high-altitude lake, Tibetan Plateau
Li, Zhaoguo; Lyu, Shihua; Zhao, Lin; Wen, Lijuan; Ao, Yinhuan; Wang, Shaoying
2016-05-01
A persistent unstable atmospheric boundary layer was observed over Lake Ngoring, caused by higher temperature on the water surface compared with the overlying air. Against this background, the eddy covariance flux data collected from Lake Ngoring were used to analyse the variation of transfer coefficients and roughness lengths for momentum, heat and moisture. Results are discussed and compared with parameterization schemes in a lake model. The drag coefficient and momentum roughness length rapidly decreased with increasing wind velocity, reached a minimum value in the moderate wind velocity and then increased slowly as wind velocity increased further. Under weak wind conditions, the surface tension or small scale capillary wave becomes more important and increases the surface roughness. The scalar roughness length ratio was much larger than unity under weak wind conditions, and it decreased to values near unity as wind velocity exceeded 4.0 m s-1. The lake model could not reproduce well the variation of drag coefficient, or momentum roughness length, versus wind velocity in Lake Ngoring, but it did simulate well the sensible heat and latent heat fluxes, as a result of complementary opposite errors.
High correlation between performance on a virtual-reality simulator and real-life cataract surgery
DEFF Research Database (Denmark)
Thomsen, Ann Sofia Skou; Smith, Phillip; Subhi, Yousif
2017-01-01
-tracking software of cataract surgical videos with a Pearson correlation coefficient of -0.70 (p = 0.017). CONCLUSION: Performance on the EyeSi simulator is significantly and highly correlated to real-life surgical performance. However, it is recommended that performance assessments are made using multiple data......PURPOSE: To investigate the correlation in performance of cataract surgery between a virtual-reality simulator and real-life surgery using two objective assessment tools with evidence of validity. METHODS: Cataract surgeons with varying levels of experience were included in the study. All...... antitremor training, forceps training, bimanual training, capsulorhexis and phaco divide and conquer. RESULTS: Eleven surgeons were enrolled. After a designated warm-up period, the proficiency-based test on the EyeSi simulator was strongly correlated to real-life performance measured by motion...
Climer, Sharlee; Yang, Wei; de las Fuentes, Lisa; Dávila-Román, Victor G; Gu, C Charles
2014-11-01
Complex diseases are often associated with sets of multiple interacting genetic factors and possibly with unique sets of the genetic factors in different groups of individuals (genetic heterogeneity). We introduce a novel concept of custom correlation coefficient (CCC) between single nucleotide polymorphisms (SNPs) that address genetic heterogeneity by measuring subset correlations autonomously. It is used to develop a 3-step process to identify candidate multi-SNP patterns: (1) pairwise (SNP-SNP) correlations are computed using CCC; (2) clusters of so-correlated SNPs identified; and (3) frequencies of these clusters in disease cases and controls compared to identify disease-associated multi-SNP patterns. This method identified 42 candidate multi-SNP associations with hypertensive heart disease (HHD), among which one cluster of 22 SNPs (six genes) included 13 in SLC8A1 (aka NCX1, an essential component of cardiac excitation-contraction coupling) and another of 32 SNPs had 29 from a different segment of SLC8A1. While allele frequencies show little difference between cases and controls, the cluster of 22 associated alleles were found in 20% of controls but no cases and the other in 3% of controls but 20% of cases. These suggest that both protective and risk effects on HHD could be exerted by combinations of variants in different regions of SLC8A1, modified by variants from other genes. The results demonstrate that this new correlation metric identifies disease-associated multi-SNP patterns overlooked by commonly used correlation measures. Furthermore, computation time using CCC is a small fraction of that required by other methods, thereby enabling the analyses of large GWAS datasets.
Directory of Open Access Journals (Sweden)
P Brandmaier
Full Text Available Previous non-simultaneous PET/MR studies have shown heterogeneous results about the correlation between standardized uptake values (SUVs and apparent diffusion coefficients (ADCs. The aim of this study was to investigate correlations in patients with primary and recurrent tumors using a simultaneous PET/MRI system which could lead to a better understanding of tumor biology and might play a role in early response assessment.We included 31 patients with histologically confirmed primary (n = 14 or recurrent cervical cancer (n = 17 who underwent simultaneous whole-body 18F-FDG-PET/MRI comprising DWI. Image analysis was performed by a radiologist and a nuclear physician who identified tumor margins and quantified ADC and SUV. Pearson correlations were calculated to investigate the association between ADC and SUV.92 lesions were detected. We found a significant inverse correlation between SUVmax and ADCmin (r = -0.532, p = 0.05 in primary tumors as well as in primary metastases (r = -0.362, p = 0.05 and between SUVmean and ADCmin (r = -0.403, p = 0.03. In recurrent local tumors we found correlations for SUVmax and ADCmin (r = -0.747, p = 0.002 and SUVmean and ADCmin (r = -0.773, p = 0.001. Associations for recurrent metastases were not significant (p>0.05.Our study demonstrates the feasibility of fast and reliable measurement of SUV and ADC with simultaneous PET/MRI. In patients with cervical cancer we found significant inverse correlations for SUV and ADC which could play a major role for further tumor characterization and therapy decisions.
Entropy measure of credit risk in highly correlated markets
Gottschalk, Sylvia
2017-07-01
We compare the single and multi-factor structural models of corporate default by calculating the Jeffreys-Kullback-Leibler divergence between their predicted default probabilities when asset correlations are either high or low. Single-factor structural models assume that the stochastic process driving the value of a firm is independent of that of other companies. A multi-factor structural model, on the contrary, is built on the assumption that a single firm's value follows a stochastic process correlated with that of other companies. Our main results show that the divergence between the two models increases in highly correlated, volatile, and large markets, but that it is closer to zero in small markets, when asset correlations are low and firms are highly leveraged. These findings suggest that during periods of financial instability, when asset volatility and correlations increase, one of the models misreports actual default risk.
DEFF Research Database (Denmark)
Poulios, Konstantinos; Svendsen, Gustav Winther; Hiller, Jochen
2013-01-01
that friction materials which are untypical for brake applications, like thermoplastics and fibre composites, can offer superior performance in terms of braking torque, wear resistance and cost than typical brake linings. In this paper coefficient of friction measurements for various thermoplastic and fibre...... composite materials running against a steel surface are presented. All tests were carried out on a pinon-disc test-rig in reciprocating operation at a fixed sliding speed and various pressure levels for both dry and grease lubricated conditions. Moreover, a generic theoretical framework is introduced...
Sürer Budak, Evrim; Toptaş, Tayfun; Aydın, Funda; Öner, Ali Ozan; Çevikol, Can; Şimşek, Tayup
2017-02-05
To explore the correlation of the primary tumor's maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin) with clinicopathologic features, and to determine their predictive power in endometrial cancer (EC). A total of 45 patients who had undergone staging surgery after a preoperative evaluation with (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) and diffusion-weighted magnetic resonance imaging (DW-MRI) were included in a prospective case-series study with planned data collection. Multiple linear regression analysis was used to determine the correlations between the study variables. The mean ADCmin and SUVmax values were determined as 0.72±0.22 and 16.54±8.73, respectively. A univariate analysis identified age, myometrial invasion (MI) and lymphovascular space involvement (LVSI) as the potential factors associated with ADCmin while it identified age, stage, tumor size, MI, LVSI and number of metastatic lymph nodes as the potential variables correlated to SUVmax. In multivariate analysis, on the other hand, MI was the only significant variable that correlated with ADCmin (p=0.007) and SUVmax (p=0.024). Deep MI was best predicted by an ADCmin cutoff value of ≤0.77 [93.7% sensitivity, 48.2% specificity, and 93.0% negative predictive value (NPV)] and SUVmax cutoff value of >20.5 (62.5% sensitivity, 86.2% specificity, and 81.0% NPV); however, the two diagnostic tests were not significantly different (p=0.266). Among clinicopathologic features, only MI was independently correlated with SUVmax and ADCmin. However, the routine use of (18)F-FDG PET/CT or DW-MRI cannot be recommended at the moment due to less than ideal predictive performances of both parameters.
Goi, Takanori; Nakazawa, Toshiyuki; Hirono, Yasuo; Yamaguchi, Akio
2015-10-06
The angiogenic proteins vascular endothelial growth factor (VEGF) and prokineticin1 (PROK1) proteins are considered important in colorectal cancer, the relationship between their simultaneous expression and prognosis was investigated in the present study. VEGF and PROK1 expression in 620 primary human colorectal cancer lesions was confirmed via immunohistochemical staining with anti-VEGF and anti-PROK1 antibodies, and the correlation between the expression of these 2 proteins and recurrence/prognosis were investigated. VEGF protein was expressed in 329 (53.1%) and PROK1 protein was expressed in 223 (36.0%). PROK1 and VEGF were simultaneously expressed in 116 (18.7%) of the 620 cases. The correlation coefficient between VEGF expression and PROK1 expression was r = 0.11, and therefore correlation was not observed. Clinical pathology revealed that substantially lymphnode matastasis, hematogenous metastasis, or TMN advanced-stage IV was significantly more prevalent in cases that expressed both VEGF and PROK1 than in the cases negative for both proteins or those positive for only 1 of the proteins. Also the cases positive for both proteins exhibited the worst recurrence and prognosis. In the Cox proportional hazards model, VEGF and PROK1 expression was an independent prognostic factor. The prognosis was poorer in colorectal cancers that expressed both PROK1 and VEGF relative to the cases that expressed only 1 protein, and the expression of both proteins was found to be an independent prognostic factor.
Chen, Jian; Bai, Xiaolong; Yang, Keji; Ju, Bing-Feng
2012-01-01
For inspection of mechanical properties and integrity of critical components such as integrated circuits or composite materials by acoustic methodology, it is imperative to evaluate their acoustic reflection coefficients, which are in close correlation with the elastic properties, thickness, density, and attenuation and interface adhesion of these layered structures. An experimental method based on angular spectrum to evaluate the acoustic coefficient as a function of the incident angle, θ, and frequency, ω, is presented with high frequency time-resolved acoustic microscopy. In order to achieve a high spatial resolution for evaluation of thin plates with thicknesses about one or two wavelengths, a point focusing transducer with a nominal center frequency of 25 MHz is adopted. By measuring the V(z, t) data in pulse mode, the reflection coefficient, R(θ, ω), can be reconstructed from its two-dimensional spectrum. It brings simplicity to experimental setup and measurement procedure since only single translation of the transducer in the vertical direction is competent for incident angle and frequency acquisition. It overcomes the disadvantages of the conventional methods requiring the spectroscopy for frequency scanning and/or ultrasonic goniometer for angular scanning. Two substrates of aluminum and Plexiglas and four stainless plates with various thicknesses of 100 μm, 150 μm, 200 μm, and 250 μm were applied. The acoustic reflection coefficients are consistent with the corresponding theoretical calculations. It opened the way of non-destructive methodology to evaluate the elastic and geometrical properties of very thin multi-layers structures simultaneously.
Vincze, Julianna; Valiskó, Mónika; Boda, Dezso
2010-10-21
We propose a simple model to explain the nonmonotonic concentration dependence of the mean activity coefficient of simple electrolytes without using any adjustable parameters. The primitive model of electrolytes is used to describe the interaction between ions computed by the adaptive grand canonical Monte Carlo method. For the dielectric constant of the electrolyte, we use experimental concentration dependent values. This is included through a solvation term in our treatment to describe the interaction between ions and water that changes as the dielectric constant changes with concentration. This term is computed by a Born-treatment fitted to experimental hydration energies. Our results for LiCl, NaCl, KCl, CsCl, NaBr, NaI, MgCl(2), CaCl(2), SrCl(2), and BaCl(2) demonstrate that the principal reason of the nonmonotonic behavior of the activity coefficient is a balance between the solvation and ion-ion correlation terms. This conclusion differs from previous studies that assumed that it is the balance of hard sphere repulsion and electrostatic attraction that produces the nonmonotonic behavior. Our results indicate that the earlier assumption that solvation can be taken into account by a larger, "solvated" ionic radius should be reconsidered. To explain second order effects (such as dependence on ionic size), we conclude that explicit water models are needed.
Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strikhanov, M. N.; Strokov, S. A.
2017-07-01
This study looks to simulate the nonlinear Compton backscattering (CBS) process based on the Monte Carlo technique for the conversion coefficient Kc ⩾ 1 , which can be considered as the average number of photons emitted by each electron. The characteristics of the nonlinear CBS process simulated in this work are as follows: the number of absorbed photons of a laser, the distance in the laser pulse in which the electron passes between two collisions, the energy and the polarization of the emitted photon in each collision, and the polarization of the electron before and after collision. The developed approach allows us to find the spectra and polarization characteristics of the final electrons and photons. When Kc > 1 , the spin-flip processes need to be considered for a correct simulation of the polarization of the final photons and electrons for energies typical of a γ- γ collider.
Neural Modeling of High-Frequency Forward Transmission Coefficient for HEMT and FinFET Technologies
Directory of Open Access Journals (Sweden)
Zlatica Marinković
2011-12-01
Full Text Available This paper is devoted to examining the ability of artificial neural networks to model the forward transmission coefficient, which represents an important figure of merit for microwave transistors. This analysis is carried out for two different on-wafer devices, namely GaAs HEMT and Si FinFET. As far as the HEMT technology is concerned, the model is developed for three devices which differ in gate width. For the FinFET technology, the model is determined not only for the whole device but also for the actual transistor by using the de-embedding procedure to subtract the effects of pads, transmission lines, and substrate from the measurements. The obtained models have been developed and validated in a wide range of bias conditions for a frequency range up to 50 GHz.
Demel, Anja; Feilke, Katharina; Wolf, Martin; Poets, Christian F.; Franz, Axel R.
2014-01-01
Near-infrared spectroscopy (NIRS) is increasingly used in neonatal intensive care. We investigated the impact of skin, bone, and cerebrospinal fluid (CSF) layer thickness in term and preterm infants on absorption-(μa) and/or reduced scattering coefficients (μs‧) measured by multidistance frequency-domain (FD)-NIRS. Transcranial ultrasound was performed to measure the layer thicknesses. Correlations were only statistically significant for μa at 692 nm with bone thickness and μs‧ at 834 nm with skin thickness. There is no evidence that skin, bone, or CSF thickness have an important effect on μa and μs‧. Layer thicknesses of skin, bone, and CSF in the range studied do not seem to affect cerebral oxygenation measurements by multidistance FD-NIRS significantly.
Rate Coefficients of the Reaction of OH with Allene and Propyne at High Temperatures
Es-Sebbar, Et Touhami
2016-09-28
Allene (H2C═C═CH2; a-C3H4) and propyne (CH3C≡CH; p-C3H4) are important species in various chemical environments. In combustion processes, the reactions of hydroxyl radicals with a-C3H4 and p-C3H4 are critical in the overall fuel oxidation system. In this work, rate coefficients of OH radicals with allene (OH + H2C═C═CH2 → products) and propyne (OH + CH3C≡CH → products) were measured behind reflected shock waves over the temperature range of 843–1352 K and pressures near 1.5 atm. Hydroxyl radicals were generated by rapid thermal decomposition of tert-butyl hydroperoxide ((CH3)3–CO–OH), and monitored by narrow line width laser absorption of the well-characterized R1(5) electronic transition of the OH A–X (0,0) electronic system near 306.7 nm. Results show that allene reacts faster with OH radicals than propyne over the temperature range of this study. Measured rate coefficients can be expressed in Arrhenius form as follows: kallene+OH(T) = 8.51(±0.03) × 10–22T3.05 exp(2215(±3)/T), T = 843–1352 K; kpropyne+OH(T) = 1.30(±0.07) × 10–21T3.01 exp(1140(±6)/T), T = 846–1335 K.
Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, Selami
2017-08-01
Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit ( ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.
Time correlations of high energy muons in an underground detector
Becherini, Y; Chiarusi, T; Cozzi, M; Dekhissi, H; Derkaoui, J; Esposito, L S; Giacomelli, G; Giglietto, N; Giorgini, M; Maaroufi, F; Mandrioli, G; Manzoor, S; Margiotta, A; Moussa, A
2005-01-01
We present the result of a search for correlations in the arrival times of high energy muons collected from 1995 till 2000 with the streamer tube system of the complete MACRO detector at the underground Gran Sasso Lab. Large samples of single muons (8.6 million), double muons (0.46 million) and multiple muons with multiplicities from 3 to 6 (0.08 million) were selected. These samples were used to search for time correlations of cosmic ray particles coming from the whole upper hemisphere or from selected space cones. The results of our analyses confirm with high statistics a random arrival time distribution of high energy cosmic rays.
Long-range correlations in high multiplicity and collisions
Indian Academy of Sciences (India)
Gunther Roland
2015-05-01
This review summarizes recent discoveries in high-energy proton+proton and proton+nucleus collisions, with particular attention on the observation of long-range azimuthal correlations in high multiplicity collisions. These correlations, which resemble those seen in ultrarelativistic nucleus–nucleus collisions, provide a unique window into the physics of the very early collision stage in high energy nuclear interactions. Here we present a compilation of the most important experimental results and briefly discuss successes and challenges for a selection of theoretical approaches.
High-speed image matching with coaxial holographic optical correlator
Ikeda, Kanami; Watanabe, Eriko
2016-09-01
A computation speed of more than 100 Gbps is experimentally demonstrated using our developed ultrahigh-speed optical correlator. To verify this high computation speed practically, the computation speeds of our optical correlator and conventional digital image matching are quantitatively compared. We use a population count function that achieves the fastest calculation speed when calculating binary matching by a central processing unit (CPU). The calculation speed of the optical correlator is dramatically faster than that using a CPU (2.40 GHz × 4) and 16 GB of random access memory, especially when the calculation data are large-scale.
Iwasaki, Shingo; Kozawa, Junji; Fukui, Kenji; Iwahashi, Hiromi; Imagawa, Akihisa; Shimomura, Iichiro
2015-08-01
In type 1 diabetic patients, insulin secretory capacity, meals and physical activity correlate with glycemic variability. Autonomic function associated with gastrointestinal motility and counterregulatory hormone secretion is another candidate which correlates with glucose variability. The aim of this study is to clarify a new clinical parameter associated with glycemic variability in insulin-depleted patients with type 1 diabetes. We studied 31 inpatients with type 1 diabetes. We evaluated glycemic variability calculated by continuous glucose monitoring, clinical parameters and the coefficient of variation of R-R interval (CVR-R). Glycemic variability was also assessed during the daytime and nighttime. The CVR-R showed a significant negative correlation with the whole-day standard deviation (SD) (r = -0.50, p = 0.007), mean amplitude of glycemic excursions (MAGE) (r = -0.47, p=0.011), M-value (r = -0.38, p = 0.048) and mean of daily differences (MODD) (r = -0.59, p = 0.001). The CVR-R also showed a significant negative correlation with the nighttime SD (r = -0.59, p = 0.001), MAGE (r = -0.47, p=0.011), M-value (r = -0.53, p = 0.004) and MODD (r = -0.65, p = 0.0003). And furthermore, the CVR-R also showed a significant negative correlation with the daytime SD (r = -0.44, p = 0.019) and MAGE (r = -0.50, p = 0.006), but not with the daytime M-value or MODD. The nighttime SD was significantly higher in patients with diabetic polyneuropathy than in patients without it (p = 0.016), while the CVR-R was significantly lower in patients with polyneuropathy than in patients without it (p = 0.009). CVR-R is closely correlated with glycemic variability, especially during nighttime, in insulin-depleted patients with type 1 diabetes. Measuring CVR-R may help us to presume the degree of glycemic variability in those patients. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Tian, Lixin [Jiangsu University, Energy Development and Environmental Protection Strategy Research Center, Zhenjiang, Jiangsu (China); Nanjing Normal University, School of Mathematical Sciences, Nanjing, Jiangsu (China); Ding, Zhenqi; Zhen, Zaili [Jiangsu University, Energy Development and Environmental Protection Strategy Research Center, Zhenjiang, Jiangsu (China); Wang, Minggang [Nanjing Normal University, School of Mathematical Sciences, Nanjing, Jiangsu (China)
2016-08-15
The international crude oil market plays a crucial role in economies, and the studies of the correlation, risk and synchronization of the international crude oil market have important implications for the security and stability of the country, avoidance of business risk and people's daily lives. We investigate the information and characteristics of the international crude oil market (1999-2015) based on the random matrix theory (RMT). Firstly, we identify richer information in the largest eigenvalues deviating from RMT predictions for the international crude oil market; the international crude oil market can be roughly divided into ten different periods by the methods of eigenvectors and characteristic combination, and the implied market information of the correlation coefficient matrix is advanced. Secondly, we study the characteristics of the international crude oil market by the methods of system risk entropy, dynamic synchronous ratio, dynamic non-synchronous ratio and dynamic clustering algorithm. The results show that the international crude oil market is full of risk. The synchronization of the international crude oil market is very strong, and WTI and Brent occupy a very important position in the international crude oil market. (orig.)
Ziolkowski, Pawel; Stiewe, Christian; de Boor, Johannes; Druschke, Ines; Zabrocki, Knud; Edler, Frank; Haupt, Sebastian; König, Jan; Mueller, Eckhard
2016-09-01
Thermoelectric generators (TEGs) convert heat to electrical energy by means of the Seebeck effect. The Seebeck coefficient is a central thermoelectric material property, measuring the magnitude of the thermovoltage generated in response to a temperature difference across a thermoelectric material. Precise determination of the Seebeck coefficient provides the basis for reliable performance assessment in materials development in the field of thermoelectrics. For several reasons, measurement uncertainties of up to 14% can often be observed in interlaboratory comparisons of temperature-dependent Seebeck coefficient or in error analyses on currently employed instruments. This is still too high for an industrial benchmark and insufficient for many scientific investigations and technological developments. The TESt (thermoelectric standardization) project was launched in 2011, funded by the German Federal Ministry of Education and Research (BMBF), to reduce measurement uncertainties, engineer traceable and precise thermoelectric measurement techniques for materials and TEGs, and develop reference materials (RMs) for temperature-dependent determination of the Seebeck coefficient. We report herein the successful development and qualification of cobalt-doped β-iron disilicide (β-Fe0.95Co0.05Si2) as a RM for high-temperature thermoelectric metrology. A brief survey on technological processes for manufacturing and machining of samples is presented. Focus is placed on metrological qualification of the iron disilicide, results of an international round-robin test, and final certification as a reference material in accordance with ISO-Guide 35 and the "Guide to the expression of uncertainty in measurement" by the Physikalisch-Technische Bundesanstalt, the national metrology institute of Germany.
Ziolkowski, Pawel; Stiewe, Christian; de Boor, Johannes; Druschke, Ines; Zabrocki, Knud; Edler, Frank; Haupt, Sebastian; König, Jan; Mueller, Eckhard
2017-01-01
Thermoelectric generators (TEGs) convert heat to electrical energy by means of the Seebeck effect. The Seebeck coefficient is a central thermoelectric material property, measuring the magnitude of the thermovoltage generated in response to a temperature difference across a thermoelectric material. Precise determination of the Seebeck coefficient provides the basis for reliable performance assessment in materials development in the field of thermoelectrics. For several reasons, measurement uncertainties of up to 14% can often be observed in interlaboratory comparisons of temperature-dependent Seebeck coefficient or in error analyses on currently employed instruments. This is still too high for an industrial benchmark and insufficient for many scientific investigations and technological developments. The TESt (thermoelectric standardization) project was launched in 2011, funded by the German Federal Ministry of Education and Research (BMBF), to reduce measurement uncertainties, engineer traceable and precise thermoelectric measurement techniques for materials and TEGs, and develop reference materials (RMs) for temperature-dependent determination of the Seebeck coefficient. We report herein the successful development and qualification of cobalt-doped β-iron disilicide ( β-Fe0.95Co0.05Si2) as a RM for high-temperature thermoelectric metrology. A brief survey on technological processes for manufacturing and machining of samples is presented. Focus is placed on metrological qualification of the iron disilicide, results of an international round-robin test, and final certification as a reference material in accordance with ISO-Guide 35 and the "Guide to the expression of uncertainty in measurement" by the Physikalisch-Technische Bundesanstalt, the national metrology institute of Germany.
National Aeronautics and Space Administration — We propose the development of nanoscale superlattices (SLs) as the active elements of high efficiency thermoelectric coolers. Recent models predict that the...
Trouble shooting for covariance fitting in highly correlated data
Yoon, Boram; Lee, Weonjong; Jung, Chulwoo
2011-01-01
We report a possible solution to the trouble that the covariance fitting fails when the data is highly correlated and the covariance matrix has small eigenvalues. As an example, we choose the data analysis of highly correlated $B_K$ data on the basis of the SU(2) staggered chiral perturbation theory. Basically, the essence of the problem is that we do not have an accurate fitting function so that we cannot fit the highly correlated and precise data. When some eigenvalues of the covariance matrix are small, even a tiny error of fitting function can produce large chi-square and spoil the fitting procedure. We have applied a number of prescriptions available in the market such as diagonal approximation and cutoff method. In addition, we present a new method, the eigenmode shift method which fine-tunes the fitting function while keeping the covariance matrix untouched.
On some hydrogen bond correlations at high pressures
Sikka, S. K.
2007-09-01
In situ high pressure neutron diffraction measured lengths of O H and H O pairs in hydrogen bonds in substances are shown to follow the correlation between them established from 0.1 MPa data on different chemical compounds. In particular, the conclusion by Nelmes et al that their high pressure data on ice VIII differ from it is not supported. For compounds in which the O H stretching frequencies red shift under pressure, it is shown that wherever structural data is available, they follow the stretching frequency versus H O (or O O) distance correlation. For compounds displaying blue shifts with pressure an analogy appears to exist with improper hydrogen bonds.
Zeng, Yun; Liu, Gang; Ma, Ying; Chen, Xiaoyuan; Ito, Yoichiro
2013-01-10
A new series of organic-high ionic strength aqueous two-phase solvents systems was designed for separation of highly polar compounds by spiral high-speed counter-current chromatography. A total of 21 solvent systems composed of 1-butanol-ethanol-saturated ammonium sulfate-water at various volume ratios are arranged according to an increasing order of polarity. Selection of the two-phase solvent system for a single compound or a multiple sample mixture can be achieved by two steps of partition coefficient measurements using a graphic method. The capability of the method is demonstrated by optimization of partition coefficient for seven highly polar samples including tartrazine (K=0.77), tryptophan (K=1.00), methyl green (K= 0.93), tyrosine (0.81), metanephrine (K=0.89), tyramine (K=0.98), and normetanephrine (K=0.96). Three sulfonic acid components in D&C Green No. 8 were successfully separated by HSCCC using the graphic selection of the two-phase solvent system.
Parkash, Jai
2008-08-01
The immunological processes in type 1 diabetes and metabolic/inflammatory disorder in type 2 diabetes converge on common signaling pathway(s) leading to beta-cell death in these two diseases. The cytokine-mediated beta-cell death seems to be dependent on voltage-dependent calcium channel (VDCC)-mediated Ca2+ entry. The Ca2+ handling molecular networks control the homeostasis of [Ca2+]i in the beta-cell. The activity and membrane density of VDCC are regulated by several mechanisms including G protein-coupled receptors (GPCRs). CaR is a 123-kDa seven transmembrane extracellular Ca2+ sensing protein that belongs to GPCR family C. Tumor necrosis factor-alpha (TNF-alpha), is a cytokine widely known to activate nuclear factor-kappaB (NF-kappaB) transcription in beta-cells. To obtain a better understanding of TNF-alpha-induced molecular interactions between CaR and VDCC, confocal fluorescence measurements were performed on insulin-producing beta-cells exposed to varying concentrations of TNF-alpha and the results are discussed in the light of increased colocalization correlation coefficient. The insulin producing beta-cells were exposed to 5, 10, 20, 30, and 50 ng/ml TNF-alpha for 24 h at 37 degrees . The cells were then immunolabelled with antibodies directed against CaR, VDCC, and NF-kappaB. The confocal fluorescence imaging data showed enhancement in the colocalization correlation coefficient between CaR and VDCC in beta-cells exposed to TNF-alpha thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. TNF-alpha-induced colocalization of VDCC with CaR was inhibited by nimodipine, an inhibitor of L-type VDCC thereby suggesting that VDCC activity is required for spatial interactions with CaR. The 3-D confocal fluorescence imaging data also demonstrated that addition of TNF-alpha to RIN cells led to the translocation of NF-kappaB from the cytoplasm to the nucleus. Such molecular interactions between CaR and VDCC in tissues
High Temperature, high pressure equation of state density correlations and viscosity correlations
Energy Technology Data Exchange (ETDEWEB)
Tapriyal, D.; Enick, R.; McHugh, M.; Gamwo, I.; Morreale, B.
2012-07-31
Global increase in oil demand and depleting reserves has derived a need to find new oil resources. To find these untapped reservoirs, oil companies are exploring various remote and harsh locations such as deep waters in Gulf of Mexico, remote arctic regions, unexplored deep deserts, etc. Further, the depth of new oil/gas wells being drilled has increased considerably to tap these new resources. With the increase in the well depth, the bottomhole temperature and pressure are also increasing to extreme values (i.e. up to 500 F and 35,000 psi). The density and viscosity of natural gas and crude oil at reservoir conditions are critical fundamental properties required for accurate assessment of the amount of recoverable petroleum within a reservoir and the modeling of the flow of these fluids within the porous media. These properties are also used to design appropriate drilling and production equipment such as blow out preventers, risers, etc. With the present state of art, there is no accurate database for these fluid properties at extreme conditions. As we have begun to expand this experimental database it has become apparent that there are neither equations of state for density or transport models for viscosity that can be used to predict these fundamental properties of multi-component hydrocarbon mixtures over a wide range of temperature and pressure. Presently, oil companies are using correlations based on lower temperature and pressure databases that exhibit an unsatisfactory predictive capability at extreme conditions (e.g. as great as {+-} 50%). From the perspective of these oil companies that are committed to safely producing these resources, accurately predicting flow rates, and assuring the integrity of the flow, the absence of an extensive experimental database at extreme conditions and models capable of predicting these properties over an extremely wide range of temperature and pressure (including extreme conditions) makes their task even more daunting.
Read-only high accuracy volume holographic optical correlator
Zhao, Tian; Li, Jingming; Cao, Liangcai; He, Qingsheng; Jin, Guofan
2011-10-01
A read-only volume holographic correlator (VHC) is proposed. After the recording of all of the correlation database pages by angular multiplexing, a stand-alone read-only high accuracy VHC will be separated from the VHC recording facilities which include the high-power laser and the angular multiplexing system. The stand-alone VHC has its own low power readout laser and very compact and simple structure. Since there are two lasers that are employed for recording and readout, respectively, the optical alignment tolerance of the laser illumination on the SLM is very sensitive. The twodimensional angular tolerance is analyzed based on the theoretical model of the volume holographic correlator. The experimental demonstration of the proposed read-only VHC is introduced and discussed.
Evapotranspiration and crop coefficients for irrigated sunflower in the southern high plains.
Sunflower (Helianthus annuus L.) is diverse crop grown for oil or confectionary uses in the Southern High Plains often under irrigation. Crop water use (evapotranspiration or ET) was measured in 2009 and 2011 in two 4-ha fields using two precision 9 m**2 weighing lysimeters containing 2.3-m deep mo...
Correlations and fluctuations in high energy heavy ion collision experiments
Institute of Scientific and Technical Information of China (English)
ZHOU Dai-Mei; WANG Ya-Ping; WEI Li-Hua; CAI Xu
2008-01-01
An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented.The experimental status on fluctuations and correlations has been reviewed and the outlook for research status of soft physics in LHC/ALICE has been introduced in this paper.
Alternative High School Students: Prevalence and Correlates of Overweight
Kubik, Martha Y.; Davey, Cynthia; Fulkerson, Jayne A.; Sirard, John; Story, Mary; Arcan, Chrisa
2009-01-01
Objective: To determine prevalence and correlates of overweight among adolescents attending alternative high schools (AHS). Methods: AHS students (n=145) from 6 schools completed surveys and anthropometric measures. Cross-sectional associations were assessed using mixed model multivariate logistic regression. Results: Among students, 42% were…
Inference for High-dimensional Differential Correlation Matrices.
Cai, T Tony; Zhang, Anru
2016-01-01
Motivated by differential co-expression analysis in genomics, we consider in this paper estimation and testing of high-dimensional differential correlation matrices. An adaptive thresholding procedure is introduced and theoretical guarantees are given. Minimax rate of convergence is established and the proposed estimator is shown to be adaptively rate-optimal over collections of paired correlation matrices with approximately sparse differences. Simulation results show that the procedure significantly outperforms two other natural methods that are based on separate estimation of the individual correlation matrices. The procedure is also illustrated through an analysis of a breast cancer dataset, which provides evidence at the gene co-expression level that several genes, of which a subset has been previously verified, are associated with the breast cancer. Hypothesis testing on the differential correlation matrices is also considered. A test, which is particularly well suited for testing against sparse alternatives, is introduced. In addition, other related problems, including estimation of a single sparse correlation matrix, estimation of the differential covariance matrices, and estimation of the differential cross-correlation matrices, are also discussed.
On discriminant analysis techniques and correlation structures in high dimensions
DEFF Research Database (Denmark)
Clemmensen, Line Katrine Harder
This paper compares several recently proposed techniques for performing discriminant analysis in high dimensions, and illustrates that the various sparse methods dier in prediction abilities depending on their underlying assumptions about the correlation structures in the data. The techniques...... generally focus on two things: Obtaining sparsity (variable selection) and regularizing the estimate of the within-class covariance matrix. For high-dimensional data, this gives rise to increased interpretability and generalization ability over standard linear discriminant analysis. Here, we group...
Li, Gui Dian; Liang, Ying Yin; Xu, Ping; Ling, Jian; Chen, Ying Ming
2016-04-01
The purpose of this study is to investigate the correlation of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values with fatty infiltration in the thigh muscles of patients with Duchenne muscular dystrophy (DMD) using diffusion-tensor imaging (DTI). Twenty-one boys with DMD were recruited. The grade of fatty infiltration and the ADC and FA values of four thigh muscles (rectus femoris, semitendinosus, sartorius, and gracilis) were measured, and the FA and ADC values were compared with the grade of fatty infiltration. Twenty age-matched healthy boys were enrolled as the control group. The differences in the ADC and FA values of the thigh muscles between patients with DMD and the control group were compared. The patients with DMD showed lower FA values and higher ADC values in all measured muscles when compared with the control group. The FA and ADC values were correlated with the grade of fatty infiltration. For the rectus femoris muscle, r = -0.753 and p = 0.007 for FA, and r = 0.685 and p = 0.001 for ADC. For the semitendinosus muscle, r = -0.621 and p = 0.041 for FA, and r = 0.705 and p = 0.021 for ADC. For the sartorius muscle, r = -0.662 and p = 0.027 for FA, and r = 0.701 and p = 0.017 for ADC. For the gracilis muscle, r = -0.618 and p = 0.043 for FA, and r = 0.695 and p = 0.022 for ADC. Damage to the thigh muscles in patients with DMD can be detected by ADC and FA values using DTI. DTI can be used to assess the severity of the disease.
Directory of Open Access Journals (Sweden)
B. Thenkalvi
2014-01-01
Full Text Available Content Based Image Retrieval (CBIR is an evolving topic under image processing. Retrieval on medical images plays a vital role in saving mankind. Medical Content Based Image Retrieval (MCBIR does not stop its work in displaying similar images; it also goes one step further for diagnosis to decide the method of therapy by comparing the query image and database image. Hence we believe that, our work is a mile stone in the medical imaging research and will gain an appreciable amount of demand in automatic diagnosis done through artificial intelligence. While handling a large amount of data base, retrieval naturally reduces the search area. Many research works were conducted on CBIR systems to yield better performance on retrieval of medical images. Here we propose a modified integrated approach which extracts low level image features: Color, intensity, shape and texture using Certain Block based Difference of Inverse Probability (CBDIP and Certain Block based Variation of Local Correlation coefficients (CBVLC for pre-processed images. Consequently wavelet moments are calculated on derived CBDIP and CBVLC values that leads to mining on medical images only with 48 feature vectors. Thereby greatly reducing total number of feature vectors used for similarity comparison for retrieval of similar images. To know the retrieval accuracy, precision and recall values are calculated for the mined 1000 images. It has been examined that this integrated approach shows an improvement in retrieval accuracy and the time taken for similarity comparison.
Ahn, Chul; Hu, Fan; Skinner, Celette Sugg; Ahn, Daniel
2009-07-01
In some cluster randomization trials, the number of clusters cannot exceed a specified maximum value due to cost constraints or other practical reasons. Donner and Klar [Donner A, and Klar N. Design and analysis of cluster randomization trials in health research. Oxford University Press 2000] provided the sample size formula for the number of subjects required per cluster when the number of clusters cannot exceed a specified maximum value. The sample size formula of Donner and Klar assumes that the number of subjects is the same in each cluster. In practical situations, the number of subjects may be different among clusters. We conducted simulation studies to investigate the effect of the cluster size variability (kappa) and the intracluster correlation coefficient (rho) on the power of the study in which the number of available clusters is fixed in advance. For the balanced case (kappa=1.0), i.e., equal cluster size among clusters, the sample size formula yielded empirical powers close to the nominal level even when the number of available clusters per group (k*) is as small as 10. The sample size formula yielded empirical powers close to the nominal level when the number of available clusters per group (k*) is at least 20 and the imbalance parameter (kappa) is at least 0.8. Empirical powers were close to the nominal level when (rho or =0.8, and k*=10) or (rho< or =0.02, kappa=0.8, and k*=20).
Rights, Jason D; Sterba, Sonya K
2016-11-01
Multilevel data structures are common in the social sciences. Often, such nested data are analysed with multilevel models (MLMs) in which heterogeneity between clusters is modelled by continuously distributed random intercepts and/or slopes. Alternatively, the non-parametric multilevel regression mixture model (NPMM) can accommodate the same nested data structures through discrete latent class variation. The purpose of this article is to delineate analytic relationships between NPMM and MLM parameters that are useful for understanding the indirect interpretation of the NPMM as a non-parametric approximation of the MLM, with relaxed distributional assumptions. We define how seven standard and non-standard MLM specifications can be indirectly approximated by particular NPMM specifications. We provide formulas showing how the NPMM can serve as an approximation of the MLM in terms of intraclass correlation, random coefficient means and (co)variances, heteroscedasticity of residuals at level 1, and heteroscedasticity of residuals at level 2. Further, we discuss how these relationships can be useful in practice. The specific relationships are illustrated with simulated graphical demonstrations, and direct and indirect interpretations of NPMM classes are contrasted. We provide an R function to aid in implementing and visualizing an indirect interpretation of NPMM classes. An empirical example is presented and future directions are discussed. © 2016 The British Psychological Society.
Shimazaki, M; Kikuchi, K; Yamaji, I; Kobayakawa, H; Yamamoto, M; Kudo, C; Wada, A; Mukai, H; Iimura, O
1991-01-01
The relationship between changes in sympathetic nerve activity and those in parasympathetic tone with a change in position was investigated in patients with essential hypertension using the coefficient of variation of RR intervals on electrocardiograms (CVRR). Mean arterial pressure (MAP), heart rate (HR), plasma noradrenaline concentration (pNA) and CVRR were measured in a supine position at rest and 20 min after having the head tilted 60 degrees superiorly in 10 normotensives (NT: 51.9 +/- 3.0 yrs) and 7 essential hypertensive patients (EHT: 51.0 +/- 2.8 yrs). After changing the position, CVRR decreased significantly in the NT, but not in the EHT; whereas, significant increases of both HR and pNA without significant changes in MAP were shown in both groups. A significant negative correlation between percentage changes in CVRR (% delta CVRR) and pNA (% delta pNA) were observed in the NT, but not in the EHT. However, there was no relationship of % delta CVRR to % delta MAP or to % delta HR in either group. It was suggested from the changes in CVRR that suppression of the parasympathetic tone, which occurs in the NT group corresponding to sympathetic augmentation to present a decrease in blood pressure with a change in position, may be impaired in the EHT group.
Mass transfer in wetted-wall columns: correlations at high Reynolds numbers
DEFF Research Database (Denmark)
Nielsen, Christian H.E.; Kiil, Søren; Thomsen, Henrik W.;
1998-01-01
The rate of gas-and liquid-phase mass transport in a pilot-scale wetted-wall column with an inner diameter of 3.26 cm and a length of 5 m was investigated. Empirical correlations for the physical liquid-phase mass transfer coefficient (k(L)(O)) and the gas-phase mass transfer coefficient (k...
Dynamical equations and transport coefficients for the metals at high pulse electromagnetic fields
Volkov, N B; Yalovets, A P
2016-01-01
We offer a metal model suitable for the description of fast electrophysical processes in conductors under influence of powerful electronic and laser radiation of femto- and picosecond duration, and also high-voltage electromagnetic pulses with picosecond front and duration less than 1 ns. The obtained dynamic equations for metal in approximation of one quasineutral liquid are in agreement with the equations received by other authors formerly. New wide-range expressions for the electronic conduction in strong electromagnetic fields are obtained and analyzed.
Dynamical equations and transport coefficients for the metals at high pulse electromagnetic fields
Volkov, N. B.; Chingina, E. A.; Yalovets, A. P.
2016-11-01
We offer a metal model suitable for the description of fast electrophysical processes in conductors under influence of powerful electronic and laser radiation of femto- and picosecond duration, and also high-voltage electromagnetic pulses with picosecond front and duration less than 1 ns. The obtained dynamic equations for metal in approximation of one quasineutral liquid are in agreement with the equations received by other authors formerly. New wide-range expressions for the electronic conduction in strong electromagnetic fields are obtained and analyzed.
Abhisek Dey; Tarun Kanti Bhattacharyya
2011-01-01
A high precision temperature compensated CMOS bandgap reference is presented. The proposed circuit employs current-mode architecture that improves the temperature stability of the output reference voltage as well as the power supply rejection when compared to the conventional voltage-mode band gap reference.Using only first order compensation the new architecture can generate an output reference voltage of 550 mV with a peak-to-peak variation of 400μV over a wide temperature range from -25oC ...
López de Haro, Mariano; Tejero, Carlos F; Santos, Andrés
2013-04-28
The problem of demixing in a binary fluid mixture of highly asymmetric additive hard spheres is revisited. A comparison is presented between the results derived previously using truncated virial expansions for three finite size ratios with those that one obtains with the same approach in the extreme case in which one of the components consists of point particles. Since this latter system is known not to exhibit fluid-fluid segregation, the similarity observed for the behavior of the critical constants arising in the truncated series in all instances, while not being conclusive, may cast serious doubts as to the actual existence of a demixing fluid-fluid transition in disparate-sized binary additive hard-sphere mixtures.
High-Resolution Rotational Spectrum, Dunham Coefficients, and Potential Energy Function of NaCl
Cabezas, C.; Cernicharo, J.; Quintana-Lacaci, G.; Peña, I.; Agundez, M.; Prieto, L. Velilla; Castro-Carrizo, A.; Zuñiga, J.; Bastida, A.; Alonso, J. L.; Requena, A.
2016-01-01
We report laboratory spectroscopy for the first time of the J = 1–0 and J = 2–1 lines of Na35Cl and Na37Cl in several vibrational states. The hyperfine structure has been resolved in both transitions for all vibrational levels, which permit us to predict with high accuracy the hyperfine splitting of the rotational transitions of the two isotopologues at higher frequencies. The new data have been merged with all previous works at microwave, millimeter, and infrared wavelengths and fitted to a series of mass-independent Dunham parameters and to a potential energy function. The obtained parameters have been used to compute a new dipole moment function, from which the dipole moment for infrared transitions up to Δv = 8 has been derived. Frequency and intensity predictions are provided for all rovibrational transitions up to J = 150 and v = 8, from which the ALMA data of evolved stars can be modeled and interpreted.
Ultraviolet Raman lidar for high-accuracy profiling of aerosol extinction coefficient
Institute of Scientific and Technical Information of China (English)
Fei Gao; Xiaoquan Song; Yufeng Wang; Yi Zhou; Dengxin Hua
2009-01-01
An ultraviolet (UV) Raman lidar system at 354.7 nm has been developed for accurately measuring the aerosol extinction profiles. A spectroscopic filter combining a high-spectral-resolution grating with two narrowband mirrors is used to separate the vibrational Raman scattering signal of N2 at a central wave-length of 386.7 nm and the elastic scattering signal at 354.7 nm. The aerosol extinction is derived from the Raman scattering of N2 and the elastic scattering by the use of Raman method and Klett method, respectively. The derived results of aerosol extinction are used to compare the difference of two retrieval methods, and the preliminary experiment shows that the Raman lidar system operated in analog detection mode has the capability of measuring aerosol profiles up to a height of 3 km with a laser energy of 250 mJ and an integration time of 8 min.
Wang, Wenbo; Mayrhofer, Patrick M.; He, Xingli; Gillinger, Manuel; Ye, Zhi; Wang, Xiaozhi; Bittner, Achim; Schmid, Ulrich; Luo, J. K.
2014-09-01
AlN and AlScN thin films with 27% scandium (Sc) were synthesized by DC magnetron sputtering deposition and used to fabricate surface acoustic wave (SAW) devices. Compared with AlN-based devices, the AlScN SAW devices exhibit much better transmission properties. Scandium doping results in electromechanical coupling coefficient, K2, in the range of 2.0% ˜ 2.2% for a wide normalized thickness range, more than a 300% increase compared to that of AlN-based SAW devices, thus demonstrating the potential applications of AlScN in high frequency resonators, sensors, and high efficiency energy harvesting devices. The coupling coefficients of the present AlScN based SAW devices are much higher than that of the theoretical calculation based on some assumptions for AlScN piezoelectric material properties, implying there is a need for in-depth investigations on the material properties of AlScN.
Institute of Scientific and Technical Information of China (English)
李伟; 朱自强
2002-01-01
The partition coefficients of baicalin were measured in ethylene oxide and propylene oxide (EOPO)/salt aqueous two-phase systemsat 298.15K. It was found that most of baicalin partitioned into EOPO-rich phase. The partition coefficients of baicalin varied from 10 to 120.The effect of various factors, including tie-line length, salt composition, molecular weight of EOPO, and solution pH, on the partition behaviorwas investigated in EOPO/salt systems. Furthermore the partition coefficients of baicalin were correlated using the modified Diamond-Hsumodel. Good agreement with experimental data is obtained. The average relative deviations are less than 5.0%.
Razek, Ahmed Abdel Khalek Abdel; Nada, Nadia
2016-04-01
The aim of this study was to measure choline/creatine (Ch/Cr) levels through (1)H-MRS and apparent diffusion coefficient (ADC) values through diffusion-weighted MRI, and to correlate these values with the prognostic parameters of head and neck squamous cell carcinoma (HNSCC). The institutional review board approved this study and informed written consent was obtained from all study participants. A prospective study of 43 patients (31 men and 12 women; mean age, 65 years) with HNSCC was conducted. Single-voxel (1)H-MRS was performed at the tumor or metastatic cervical lymph node with point-resolved spectroscopy (PRESS) at TE = 135 ms. Diffusion-weighted MR images with b values of 0, 500 and 1000 s/mm(2) and contrast MRI of the head and neck were performed. The Ch/Cr levels and ADC values of HNSCC were calculated. The gross tumor volume (GTV) was also calculated. The degree of tumor differentiation was determined through pathological examination. The HNSCC Ch/Cr level was negatively correlated with the ADC value (r = -0.662, p = 0.001). There was a significant difference in the Ch/Cr and ADC values at different degrees of tumor differentiation (p = 0.003 and p = 0.001) and with different GTVs (p = 0.122 and p = 0.001). The following prognostic parameter categories were used: (i) poorly differentiated and undifferentiated versus well differentiated to moderately differentiated; and (ii) HNSCC with GTV 30 cm(3). The cut-off values for Cho/Cr and ADC for each category were 1.83, 0.95 and 1.94, 0.99, respectively, and the areas under the curve were 0.771, 0.967 and 0.726, 0.795, respectively, for each category. We conclude that the Ch/Cr levels determined using (1)H-MRS and the ADC values are well correlated with several prognostic parameters of HNSCC.
Energy Technology Data Exchange (ETDEWEB)
Huang, C.-C. [Department of Electronic Engineering, Fu Jen Catholic University, Taipei 24205, Taiwan (China); Chen Ruimin; Zhou Qifa; Shung, K Kirk [NIH Resource on Medical Ultrasonic Transducer Technology, Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089 (United States); Tsui, P.-H. [Division of Mechanics, Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Humayun, Mark S [Doheny Retina Institute, Doheny Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States)], E-mail: j648816n@ms23.hinet.net
2009-10-07
A cataract is a clouding of the lens in the eye that affects vision. Phacoemulsification is the mostly common surgical method for treating cataracts, and determining that the optimal phacoemulsification energy is dependent on measuring the hardness of the lens. This study explored the use of an ultrasound needle transducer for invasive measurements of ultrasound attenuation coefficient to evaluate the hardness of the cataract lens. A 47 MHz high-frequency needle transducer with a diameter of 0.9 mm was fabricated by a polarized PMN-33%PT single crystal in the present study. The attenuation coefficients at different stages of an artificial porcine cataract lens were measured using the spectral shift approach. The hardness of the cataract lens was also evaluated by mechanical measurement of its elastic properties. The results demonstrated that the ultrasonic attenuation coefficient was increased from 0.048 {+-} 0.02 to 0.520 {+-} 0.06 dB mm{sup -1} MHz{sup -1} corresponding to an increase in Young's modulus from 6 {+-} 0.4 to 96 {+-} 6.2 kPa as the cataract further developed. In order to evaluate the feasibility of combining needle transducer and phacoemulsification probe for real-time measurement during cataract surgery, the needle transducer was mounted on the phacoemulsification probe for a vibration test. The results indicated that there was no apparent damage to the tip of the needle transducer and the pulse-echo test showed that a good performance in sensitivity was maintained after the vibration test.
A Tale of Two Electrons: Correlation at High Density
Loos, Pierre-François
2010-01-01
We review our recent progress in the determination of the high-density correlation energy $\\Ec$ in two-electron systems. Several two-electron systems are considered, such as the well known helium-like ions (helium), and the Hooke's law atom (hookium). We also present results regarding two electrons on the surface of a sphere (spherium), and two electrons trapped in a spherical box (ballium). We also show that, in the large-dimension limit, the high-density correlation energy of two opposite-spin electrons interacting {\\em via} a Coulomb potential is given by $\\Ec \\sim -1/(8D^2)$ for any radial external potential $V(r)$, where $D$ is the dimensionality of the space. This result explains the similarity of $\\Ec$ in the previous two-electron systems for $D=3$.
Covariance fitting of highly correlated $B_K$ data
Yoon, Boram; Jung, Chulwoo; Lee, Weonjong
2011-01-01
We present the reason why we use the diagonal approximation (uncorrelated fitting) when we perform the data analysis of highly correlated $B_K$ data on the basis of the SU(2) staggered chiral perturbation theory. Basically, the essence of the problem is that we do not have enough statistics to determine the small eigenvalues of the covariance matrix with a high precision. As a result, we have the smallest eigenvalue, which is smaller than the statistical error of the covariance matrix, corresponding to an unphysical eigenmode. We have applied a number of prescriptions available in the market such as the cutoff method and modified covariance matrix method. It turns out that the cutoff method is not a good prescription and the modified covariance matrix method is an even worse one. The diagonal approximation turns out to be a good prescription if the data points are somehow correlated and the statistics are relatively poor.
Park, Seoung-Hwan; Ahn, Doyeol; Park, Chan-Yong
2017-02-20
Intersubband absorption properties of lattice-matched BGaN/AlN quantum well (QW) structures grown on AlN substrate are theoretically investigated using an effective mass theory considering the nonparabolicity of the conduction band. These results are compared with those of GaN/AlN QW structures. The intersubband absorption coefficient of the BGaN/AlN QW structure is shown to be enhanced significantly, compared to that of the conventional GaN/AlN QW structure. This can be explained by the fact that the BGaN/AlN QW structure exhibits larger intersuband dipole moment and quasi-Fermi-level separation than the GaN/AlN QW structure, due to the increase in the carrier confinement by a larger internal field. We expect that the BGaN/AlN QW structure with a high absorption coefficient can be used for telecommunication applications at 1.55 µm under the lattice-matched condition, instead of the conventional GaN/AlN QW structure with the large strain.
Tanaka, Hiroaki; Takahashi, Sachiko; Yamanaka, Mari; Yoshizaki, Izumi; Sato, Masaru; Sano, Satoshi; Motohara, Moritoshi; Kobayashi, Tomoyuki; Yoshitomi, Susumu; Tanaka, Tetsuo; Fukuyama, Seijiro
2006-09-01
The diffusion coefficients of lysozyme and alpha-amylase were measured in the various polyethylene glycol (PEG) solutions. Obtained diffusion coefficients were studied with the viscosity coefficient of the solution. It was found that the diffusion process of the protein was suppressed with a factor of vγ, where ν is a relative viscosity coefficient of the PEG solution. The value of γ is -0.64 at PEG1500 for both proteins. The value increased to -0.48 at PEG8000 for lysozyme, while decreased to -0.72 for alpha-amylase. The equation of an approximate diffusion coefficient at certain PEG molecular weight and concentration was roughly obtained.
Hanson, A A; Moon, R D; Wright, R J; Hunt, T E; Hutchison, W D
2015-08-01
Western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a native, univoltine pest of corn and dry beans in North America. The current degree-day model for predicting a specified percentage of yearly moth flight involves heat unit accumulation above 10°C after 1 May. However, because the moth's observed range has expanded into the northern and eastern United States, there is concern that suitable temperatures before May could allow for significant S. albicosta development. Daily blacklight moth catch and temperature data from four Nebraska locations were used to construct degree-day models using simple or sine-wave methods, starting dates between 1 January and 1 May, and lower (-5 to 15°C) and upper (20 to 43.3°C) developmental thresholds. Predicted dates of flight from these models were compared with observed flight dates using independent datasets to assess model performance. Model performance was assessed with the concordance correlation coefficient to concurrently evaluate precision and accuracy. The best model for predicting timing of S. albicosta flight used simple degree-day calculations beginning on 1 March, a 3.3°C (38°F) lower threshold, and a 23.9°C (75°F) upper threshold. The revised cumulative flight model indicated field scouting to estimate moth egg density at the time of 25% flight should begin when 1,432 degree-days (2,577 degree-days °F) have accumulated. These results underscore the importance of assessing multiple parameters in phenological models and utilizing appropriate assessment methods, which in this case may allow for improved timing of field scouting for S. albicosta.
Kong, Eunjung; Chun, Kyung Ah; Cho, Ihn Ho
2017-01-01
Metabolism and water diffusion may have a relationship or an effect on each other in the same tumor. Knowledge of their relationship could expand the understanding of tumor biology and serve the field of oncologic imaging. This study aimed to evaluate the relationship between metabolism and water diffusivity in hepatic tumors using a simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) system with F-18 fluorodeoxyglucose (FDG) and to reveal the metabolic and diffusional characteristics of each type of hepatic tumor. Forty-one patients (mean age 63 ± 13 years, 31 male) with hepatic tumors (18 hepatocellular carcinoma [HCC], six cholangiocarcinoma [CCC], 10 metastatic tumors, one neuroendocrine malignancy, and six benign lesions) underwent FDG PET/MRI before treatment. Maximum standard uptake (SUVmax) values from FDG PET and the apparent diffusion coefficient (ADC) from the diffusion-weighted images were obtained for the tumor and their relationships were examined. We also investigated the difference in SUVmax and ADC for each type of tumor. SUVmax showed a negative correlation with ADC (r = -0.404, p = 0.009). The median of SUVmax was 3.22 in HCC, 6.99 in CCC, 6.30 in metastatic tumors, and 1.82 in benign lesions. The median of ADC was 1.039 × 10-3 mm/s2 in HCC, 1.148 × 10-3 mm/s2 in CCC, 0.876 × 10-3 mm/s2 in metastatic tumors, and 1.323 × 10-3 mm/s2 in benign lesions. SUVmax was higher in metastatic tumors than in benign lesions (p = 0.023). Metastatic tumors had a lower ADC than CCC (p = 0.039) and benign lesions (p = 0.004). HCC had a lower ADC than benign lesions, with a suggestive trend (p = 0.06). Our results indicate that SUVmax is negatively correlated with ADC in hepatic tumors, and each group of tumors has different metabolic and water diffusivity characteristics. Evaluation of hepatic tumors by PET/MRI could be helpful in understanding tumor characteristics.
Dynamics of Coulomb correlations in semiconductors in high magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Fromer, Neil Alan [Univ. of California, Berkeley, CA (United States)
2002-01-01
Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are not present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.
Dynamics of Coulomb correlations in semiconductors in high magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Fromer, Neil Alan
2002-05-01
Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are not present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.
Directory of Open Access Journals (Sweden)
Ivankova Olga
2017-01-01
Full Text Available This paper deals with the analysis of 21-storeyed cast in-situ reinforced concrete high-rise building. Two different 3D models were created, because of two considered values of subsoil stiffness coefficient -fixed structure (alt. 1 and the structure supported by elastic soil (alt. 2. For both alternatives of foundation of structure, required analyses (static and dynamic were done and obtained results were compared in this paper. Short description of the structure, applied loads and other input parameters are also mentioned here. The main purpose of this analysis was to provide more information to planning engineers about the behaviour of structure exposed the wind load or seismic load when different soil conditions were considered.
Ballesteros, E.; Collados, M.; Bonet, J. A.; Lorenzo, F.; Viera, T.; Reyes, M.; Rodriguez Hidalgo, I.
1996-02-01
In this paper the description of the Solar Correlation Tracker prototype built by the Instituto de Astrof isica de Canarias is presented. The system is mainly conceived as a solar image tranquilizer, although a scanning utility has also been included in order to displace the image on the final focal plane with sub-arcsecond steps, thus allowing to perform two-dimensional high spatial resolution spectroscopy. The behaviour of the different elements of the tracker is shown, as well as their influence in the performance of the system. The restrictions of the Absolute Differences algorithm, used to detect image motion when granulation fields are considered, are extensively discussed. Laboratory and telescope tests have demonstrated the capabilities of the system. The electronic components have been adapted to new optics and mechanics developed at the Kiepenheuer Institut to build an Advanced Solar Correlation Tracker. The final version of the system has been installed at the German VTT of the Spanish Observatorio del Teide. The tests carried out have demonstrated that a bandwidth of about 60Hz (for an attenuation factor of two) is achieved, which is approximately four times larger than that of previous Correlation Trackers, at the same level of attenuation.
High-harmonic generation enhanced by dynamical electron correlation
Tikhomirov, Iliya; Ishikawa, Kenichi L
2016-01-01
We theoretically study multielectron effects in high-harmonic generation (HHG), using all-electron first-principles simulations for a one-dimensional (1D) model atom. In addition to usual plateau and cutoff (from a cation in the present case, since the neutral is immediately ionized), we find a prominent resonance peak far above the plateau and a second plateau extended beyond the first cutoff. These features originate from the dication response enhanced by orders of magnitude due to the action of the Coulomb force from the rescattering electron, and, hence, are a clear manifestation of electron correlation. Although the present simulations are done in 1D, the physical mechanism underlying the dramatic enhancement is expected to hold also for three-dimensional real systems. This will provide new possibilities to explore dynamical electron correlation in intense laser fields using HHG, which is usually considered to be of single-electron nature in most cases.
SPIDER Progress Towards High Resolution Correlated Fission Product Data
Shields, Dan; Meierbachtol, Krista; Tovesson, Fredrik; Arnold, Charles; Blackeley, Rick; Bredeweg, Todd; Devlin, Matt; Hecht, Adam; Jandel, Marian; Jorgenson, Justin; Nelson, Ron; White, Morgan; Spider Team
2014-09-01
The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. The SPIDER detector (SPectrometer for Ion DEtermination in fission Research) is under development with the goal of obtaining high-resolution, high-efficiency, correlated fission product data needed for many applications including the modeling of next generation nuclear reactors, stockpile stewardship, and the fundamental understanding of the fission process. SPIDER simultaneously measures velocity and energy of both fission products to calculate fission product yields (FPYs), neutron multiplicity (ν), and total kinetic energy (TKE). A detailed description of the prototype SPIDER detector components will be presented. Characterization measurements with alpha and spontaneous fission sources will also be discussed. LA-UR-14-24875. This work is in part supported by LANL Laboratory Directed Research and Development Projects 20110037DR and 20120077DR.
Karan, Belgin; Pourbagher, Aysin; Torun, Nese
2016-06-01
To evaluate the correlations between the apparent diffusion coefficient (ADC) value and the standardized uptake value (SUV) with prognostic factors in breast cancer. Seventy women with invasive breast cancer (56 cases of invasive ductal carcinoma, four of mixed ductal and lobular invasive carcinoma, three of lobular invasive carcinoma, two of micropapillary carcinoma, and one each of mixed ductal and mucinous carcinoma, mucinous carcinoma, medullary carcinoma, metaplastic carcinoma, and tubular carcinoma) were included in this study. All patients underwent presurgical breast magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) at 1.5T and whole-body (18) F-fluorodeoxyglucose ((18) F-FDG) positron emission tomography (PET) / computed tomography (CT). For all invasive breast cancers and invasive ductal carcinomas, we assessed the relationships among ADC, SUV, and pathological prognostic factors. Both the median ADC value and maximum SUV (SUVmax) were significantly associated with vascular invasion (P = 0.008 and P = 0.026, respectively). SUVmax was also significantly correlated with tumor size (P = 0.001), histological grade (P = 0.001), lymph node status (P = 0.0015), estrogen receptor status (P = 0.010), and human epidermal growth factor receptor 2 status (P = 0.020), whereas ADC values were not. The correlation between the ADC and SUVmax was not significant (P = 0.356; R = -0.112). Mucinous carcinoma showed high ADC and relatively low SUVmax. Medullary carcinoma showed low ADC and high SUVmax. When we evaluated the relationships among ADC, SUVmax, and prognostic factors in the 56 invasive ductal carcinomas, our statistical results were not significantly changed, except SUVmax was also significantly associated with progesterone receptor status (P = 0.034), but not lymph node status. SUVmax may be valuable for predicting the prognosis of breast cancer. Both ADC and SUVmax are useful to predict vascular invasion. J. Magn. Reson. Imaging 2016
Statistical analysis of highly correlated systems in biology and physics
Martin, Hector Garcia
In this dissertation, I present my work on the statistical study of highly correlated systems in three fields of science: ecology, microbial ecology and physics. I propose an explanation for how the highly correlated distribution of species individuals, and an abundance distribution commonly observed in ecological systems, give rise to a power law dependence between a given area and the number of unique species it harbors. This is one of the oldest known ecological patterns: the power-law Species Area Rule. As a natural extension of my studies in ecology, I have undertaken both theoretical research and field work in the developing field of microbial ecology. In particular, I participated in a multidisciplinary study of the impact of microbes on the formation of macroscopic calcium carbonate terraces at Yellowstone National Park Hot Springs. I have used ecological techniques to characterize the biodiversity of our study site and developed a new bootstrap method for extracting abundance information from clone libraries. This has singled out the most abundant microorganisms and paved the way for future studies of the possible non-passive role of microorganisms in carbonate precipitation. The third part of my thesis uses statistical techniques to explore the correlations in rotating Bose-Einstein condensates. I have used finite difference techniques to solve the Gross-Pitaevskii equation in order to obtain the structure of a vortex in a lattice. Surprisingly, I have found that, in order to understand this structure, it is necessary to add a correction to the Gross-Pitaevskii equation which introduces a dependence on the particle scattering length. I have also used Path Integral Monte Carlo techniques to explore the limit of rapid rotations, where the Gross-Pitaevskii equation is no longer valid. Interestingly, the Gross-Pitaevskii equation seems to be valid for much higher densities than expected if properly renormalized. I show that, in accord with the prediction of
Zhou, Shiqi; Solana, J R
2013-08-08
The first three coefficients of the high temperature series expansion (HTSE) of the Helmholtz free energy for a number of simple potential models with hard-sphere cores plus continuous tails are obtained for the first time from Monte Carlo simulations. The potential models considered include Square-well, Sutherland, attractive Yukawa, and triangle-well with different potential ranges, as well as a model potential qualitatively resembling the depletion potential in colloidal dispersions. The simulation data are used to evaluate performance of a recent coupling parameter series expansion (CPSE) in calculating for these coefficients, and a traditional macroscopic compressibility approximation (MCA) for the second-order coefficient only. A comprehensive comparison based on these coefficients from the two theoretical approaches and simulations enables one to conclude that (i) unlike one common experience that the widely used MCA usually underestimates the second-order coefficient, the MCA can both overestimate and underestimate the second-order coefficient, and worsens as the range of the potential decreases; and (ii) in contrast, the CPSE not only reproduce the trends in the density dependence of the perturbation coefficients, even the third one, observed in the simulations, but also the agreement is quantitative in most cases, and this clearly highlights the potential of the CPSE in providing accurate estimations for the higher-order coefficients, thus giving rise to an accurate higher-order HTSE.
Echavarría-Heras, Héctor; Leal-Ramírez, Cecilia; Villa-Diharce, Enrique; Castillo, Oscar
2014-01-01
Eelgrass is a cosmopolitan seagrass species that provides important ecological services in coastal and near-shore environments. Despite its relevance, loss of eelgrass habitats is noted worldwide. Restoration by replanting plays an important role, and accurate measurements of the standing crop and productivity of transplants are important for evaluating restoration of the ecological functions of natural populations. Traditional assessments are destructive, and although they do not harm natural populations, in transplants the destruction of shoots might cause undesirable alterations. Non-destructive assessments of the aforementioned variables are obtained through allometric proxies expressed in terms of measurements of the lengths or areas of leaves. Digital imagery could produce measurements of leaf attributes without the removal of shoots, but sediment attachments, damage infringed by drag forces or humidity contents induce noise-effects, reducing precision. Available techniques for dealing with noise caused by humidity contents on leaves use the concepts of adjacency, vicinity, connectivity and tolerance of similarity between pixels. Selection of an interval of tolerance of similarity for efficient measurements requires extended computational routines with tied statistical inferences making concomitant tasks complicated and time consuming. The present approach proposes a simplified and cost-effective alternative, and also a general tool aimed to deal with any sort of noise modifying eelgrass leaves images. Moreover, this selection criterion relies only on a single statistics; the calculation of the maximum value of the Concordance Correlation Coefficient for reproducibility of observed areas of leaves through proxies obtained from digital images. Available data reveals that the present method delivers simplified, consistent estimations of areas of eelgrass leaves taken from noisy digital images. Moreover, the proposed procedure is robust because both the optimal
Suicidal ideation in high school students: depression and other correlates.
De Man, A F; Leduc, C P
1995-03-01
English-Canadian high school students (129 boys, 117 girls) participated in a study of the relationship between suicidal ideation and selected personal variables, stress, and social support. Associations were found between suicidal ideation and the variables of gender, self-esteem, locus of control, depression, drug use, stress, perception of health, family status, academic performance, social support, and anomie. Multiple regression analysis identified depression and alcohol use as best individual predictors among these variables. Semi-partial correlation analyses showed that removal of the effect of depression resulted in a loss of initially significant relationships between suicidal ideation and the other variables except for alcohol use, drug use, and health satisfaction.
Azamathulla, H. Md.; Jarrett, Robert D.
2013-01-01
Manning’s roughness coefficient (n) has been widely used in the estimation of flood discharges or depths of flow in natural channels. Therefore, the selection of appropriate Manning’s nvalues is of paramount importance for hydraulic engineers and hydrologists and requires considerable experience, although extensive guidelines are available. Generally, the largest source of error in post-flood estimates (termed indirect measurements) is due to estimates of Manning’s n values, particularly when there has been minimal field verification of flow resistance. This emphasizes the need to improve methods for estimating n values. The objective of this study was to develop a soft computing model in the estimation of the Manning’s n values using 75 discharge measurements on 21 high gradient streams in Colorado, USA. The data are from high gradient (S > 0.002 m/m), cobble- and boulder-bed streams for within bank flows. This study presents Gene-Expression Programming (GEP), an extension of Genetic Programming (GP), as an improved approach to estimate Manning’s roughness coefficient for high gradient streams. This study uses field data and assessed the potential of gene-expression programming (GEP) to estimate Manning’s n values. GEP is a search technique that automatically simplifies genetic programs during an evolutionary processes (or evolves) to obtain the most robust computer program (e.g., simplify mathematical expressions, decision trees, polynomial constructs, and logical expressions). Field measurements collected by Jarrett (J Hydraulic Eng ASCE 110: 1519–1539, 1984) were used to train the GEP network and evolve programs. The developed network and evolved programs were validated by using observations that were not involved in training. GEP and ANN-RBF (artificial neural network-radial basis function) models were found to be substantially more effective (e.g., R2 for testing/validation of GEP and RBF-ANN is 0.745 and 0.65, respectively) than
DEFF Research Database (Denmark)
Helweg, C.; Nielsen, T.; Hansen, P.E.
1997-01-01
Prediction of 1-octanol water partition coefficients for a range of polar N-PAC from HPLC capacity coefficients has been investigated. Two commercially available columns, an ODS column and a Diol column were tested with water-methanol eluents. The best prediction of log K-ow for N-PAC was achieve...
Pfrang, Christian; King, Martin D.; Braeckevelt, Mareike; Canosa-Mas, Carlos E.; Wayne, Richard P.
Experimental difficulties sometimes force modellers to use predicted rate coefficients for reactions of oxygenated volatile organic compounds (oVOCs). We examine here methods for making the predictions for reactions of atmospheric initiators of oxidation, NO 3, OH, O 3 and O( 3P), with unsaturated alcohols and ethers. Logarithmic correlations are found between measured rate coefficients and calculated orbital energies, and these correlations may be used directly to estimate rate coefficients for compounds where measurements have not been performed. To provide a shortcut that obviates the need to calculate orbital energies, structure-activity relations (SARs) are developed. Our SARs are tested for predictive power against compounds for which experimental rate coefficients exist, and their accuracy is discussed. Estimated atmospheric lifetimes for oVOCs are presented. The SARs for alkenols successfully predict key rate coefficients, and thus can be used to enhance the scope of atmospheric models incorporating detailed chemistry. SARs for the ethers have more limited applicability, but can still be useful in improving tropospheric models.
Geith, Tobias; Biffar, Andreas; Schmidt, Gerwin; Sourbron, Steven; Dietrich, Olaf; Reiser, Maximilian; Baur-Melnyk, Andrea
2015-01-01
To test the hypothesis that apparent diffusion coefficient (ADC) in vertebral bone marrow of benign and malignant fractures is related to the volume of the interstitial space, determined with dynamic contrast-enhanced (DCE) magnetic resonance imaging. Patients with acute benign (n = 24) and malignant (n = 19) vertebral body fractures were examined at 1.5 T. A diffusion-weighted single-shot turbo-spin-echo sequence (b = 100 to 600 s/mm) and DCE turbo-FLASH sequence were evaluated. Regions of interest were manually selected for each fracture. Apparent diffusion coefficient was determined with a monoexponential decay model. The DCE magnetic resonance imaging concentration-time curves were analyzed using a 2-compartment tracer-kinetic model. Apparent diffusion coefficient showed a significant positive correlation with interstitial volume in the whole study population (Pearson r = 0.66, P correlation between ADC and the permeability-surface area product could be observed when analyzing the whole study population (Spearman rs = 0.40, P = 0.008), but not when separately examining the subgroups. Plasma flow showed a significant correlation with ADC in benign fractures (Pearson r = 0.23, P = 0.03). Plasma volume did not show significant correlations with ADC. The results support the hypothesis that the ADC of a lesion is inversely correlated to its cellularity. This explains previous observations that ADC is reduced in more malignant lesions.
Institute of Scientific and Technical Information of China (English)
苑津莎; 尚海昆; 王瑜; 靳松
2013-01-01
针对变压器局部放电模式分类过程中特征参数维数过高的问题，提出了一种基于相关系数矩阵的参数降维方法。利用提取出的变压器局部放电信号的特征参数构造相关系数矩阵，通过分析放电信号18个特征参数间的相关性，删除具有相似分类能力的特征参数，之后引入分离度指标来衡量特征向量的分类能力大小，提取出6个具有较高分类能力的特征向量，最后通过概率神经网络进行模式识别。结果表明该降维方法有效降低了特征参数的维数，简化了分类器结构，在小样本情况下对于概率神经网络模式分类器具有较高的识别率，识别效果优于传统BP神经网络。%A new dimension reduction method based on correlation coefficient matrix is proposed aimed at the high-dimension of characteristic parameters in the process of pattern recognition for partial discharge in power transformer. The correlation coefficient matrix (CCM) is constructed using parameters extracted from partial discharge signal in power transformer. The parameters which have similar classification ability to each other are deleted with the help of correlation analysis among 18 characteristic parameters in CCM. Six parameters which have higher classification capabilities are extracted using the critical index and are used as the inputs for pattern classifiers of probabilistic neural networks. The results show that the parameter dimension is reduced and the classifier construction is simplified, and the recognition effect is better than that of the traditional back propagation neural network in the condition of small samples.
Energy Technology Data Exchange (ETDEWEB)
Nash, Charles A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, Frank G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, Daniel J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2014-12-19
The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant (WTP) that is currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and poured into canisters for disposition. The LAW glass will be disposed onsite in the Integrated Disposal Facility (IDF). There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the water solubility properties of pertechnetate and long half-life of ^{99}Tc, effective management of ^{99}Tc is important to the overall success of the Hanford River Protection Project mission. To achieve the full target WTP throughput, additional LAW immobilization capacity is needed, and options are being explored to immobilize the supplemental LAW portion of the tank waste. Removal of ^{99}Tc, followed by off-site disposal, would eliminate a key risk contributor for the IDF Performance Assessment (PA) for supplemental waste forms, and has potential to reduce treatment and disposal costs. Washington River Protection Solutions (WRPS) is developing some conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal. One of these flowsheets will specifically examine removing ^{99}Tc from the LAW feed stream to supplemental immobilization. To enable an informed decision regarding the viability of technetium removal, further maturation of available technologies is being performed. This report contains results of experimental ion exchange distribution coefficient testing and computer modeling using the resin SuperLig^{®} 639^{a} to selectively remove perrhenate from high ionic strength simulated LAW. It is advantageous to operate at higher concentration in order to treat the waste
Energy Technology Data Exchange (ETDEWEB)
Mimura, Kojiro; Ishizu, Takahiko; Yamamoto, Kazuya; Takasu, Junta; Yonehira, Yuri; Taguchi, Yukihiro; Ichikawa, Kouichi [Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Wakita, Kazuki [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, Narashino, Chiba (Japan); Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan); Yan, Ke; Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute, Kouto, Sayo-cho (Japan); Kobayashi, Keisuke [National Institute for Materials Science, Kouto, Sayo-cho, Sayo-gun, Hyogo (Japan)
2009-05-15
The temperature dependence of the core-level and valence-band electronic structures of TlGaTe{sub 2} and TlInSe{sub 2} that exhibits high values of Seebeck coefficient has been studied by hard X-ray photoemission spectroscopy over the temperature range 40-450 K. The relative peak position and peak width for Tl 4f, Ga 2p and Te 3d in TlGaTe{sub 2} are determined. It is shown that not only chemical shift defying the peak position but also electron-phonon interaction responsible for temperature line-broadening has rather peculiar temperature behaviour that reflects incommensurate phase transition. Thermoelectric power of TlGaTe{sub 2} is evaluated and found to be very close to that of TlInSe{sub 2}. It is shown that Tl 4f spectra of both compounds also display close similarity (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Driessen, Juliette P; van Bemmel, Xander; van Kempen, Pauline M. W.; Janssen, Luuk M; Terhaard, Chris H J; Pameijer, Frank A; Willems, Stefan M.; Stegeman, Inge; Grolman, Wilko; Philippens, Marielle E P
2016-01-01
Background Identification of prognostic patient characteristics in head and neck squamous cell carcinoma (HNSCC) is of great importance. Human papillomavirus (HPV)-positive HNSCCs have favorable response to (chemo)radiotherapy. Apparent diffusion coefficient, derived from diffusion-weighted MRI, has
On temporal correlations in high-resolution frequency counting
Dunker, Tim; Rønningen, Ole Petter
2016-01-01
We analyze noise properties of time series of frequency data from different counting modes of a Keysight 53230A frequency counter. We use a 10 MHz reference signal from a passive hydrogen maser connected via phase-stable Huber+Suhner Sucoflex 104 cables to the reference and input connectors of the counter. We find that the high resolution gap-free (CONT) frequency counting process imposes long-term correlations in the output data, resulting in a modified Allan deviation that is characteristic of random walk phase noise. Equally important, the CONT mode results in a frequency bias. In contrast, the counter's undocumented raw continuous mode (RCON) yields unbiased frequency stability estimates with white phase noise characteristics, and of a magnitude consistent with the counter's 20 ps single-shot resolution. Furthermore, we demonstrate that a 100-point running average filter in conjunction with the RCON mode yields resolution enhanced frequency estimates with flicker phase noise characteristics. For instance,...
Oxidative stress at high altitude: genotype–phenotype correlations
Directory of Open Access Journals (Sweden)
Pandey P
2014-05-01
Full Text Available Priyanka Pandey,1,2 MA Qadar Pasha1,2 1CSIR-Institute of Genomics and Integrative Biology, Delhi, India; 2Department of Biotechnology, University of Pune, Ganeshkhind, Pune, India Abstract: It has been well-documented that the hypobaric hypoxic environment at high altitude (HA causes stress to both the permanent residents of HA and the sojourners. This oxidative stress primarily disturbs the oxygen-sensing and vascular homeostasis pathways, thereby upsetting normal human physiology, especially in sojourners. These environmental challenges have caused dynamic evolutionary changes within natives of HA, allowing them to develop adaptive plasticity. This review focuses on the genomic and biochemical features of the molecules involved in the oxygen-sensing and vascular homeostasis pathways with respect to HA pulmonary edema (HAPE and adaptation. We review the role of genetic markers such as HIF-prolyl hydroxylase 2, endothelial PAS domain-containing protein 1, endothelial nitric oxide synthase, endothelin 1, cytochrome b-245 alpha polypeptide, and glutathione S-transferase pi 1, as well as three circulatory biomarkers (nitric oxide, endothelin 1, and 8-iso-prostaglandin F2α, by highlighting approaches such as candidate gene and genome-wide, adopted in deciphering the pathways. A disagreement between the two approaches has also been highlighted. In addition, we discuss that an overrepresentation of wild-type alleles in HA natives and mutant alleles of same polymorphisms in HAPE patients implies that the allelic variants at the same locus are involved in adaptation and HAPE, respectively. Moreover, healthy sojourners present a number of genomic features similar to HA natives, further strengthening the concept of genetic predisposition. A trend in correlation between protective and risk alleles and altered levels of circulatory markers clearly documents the phenomenon of genotype–phenotype correlations. We conclude that the genetic and biochemical
Manifestation of proton structure in ridge-like correlations in high-energy proton-proton collisions
Kubiczek, Patryk
2015-01-01
Recently, the CMS collaboration reported a long range in rapidity, near-side ('ridge-like') angular correlations in high-energy proton-proton collisions, so called ridge effect. This surprising observation suggests the presence of a collective flow that resembles the one believed to produce a similar correlation hydrodynamically in heavy-ion collisions. If the hydrodynamic description is valid then the effect is triggered by the initial spatial anisotropy of the colliding matter. Estimating this anisotropy within different models of the proton internal structure in comparison with measured angular correlations in high-energy proton-proton collision data could in principle discriminate between different proton models. Inspired by recent theoretical developments, we propose several phenomenological models of the proton structure. Subsequently, we calculate the anisotropy coefficients of the dense matter formed in proton-proton collisions within the formalism of the Monte Carlo Glauber model. We find that some p...
Positive Correlation Between Academic Library Services and High-Impact Practices for
Directory of Open Access Journals (Sweden)
Saori Wendy Herman, MLIS, AHIP
2016-03-01
Full Text Available Objective – To investigate the perceived alignment between academic library services and high-impact practices (HIPs that affect student retention. Design – Survey questionnaire. Setting – Public comprehensive universities in the United States of America with a Carnegie classification of master’s level as of January 2013. Subjects – 68 library deans or directors out of the 271 who were originally contacted. Methods – The author used Qualtrics software to create a survey based on the HIPs, tested the survey for reliability, and then distributed it to 271 universities. Library services were grouped into 1 of 3 library scales: library collection, library instruction, or library facilities. The survey consisted of a matrix of 10 Likert-style questions addressing the perceived level of alignment between the library scales and the HIPs. Each question provided an opportunity for the respondent to enter a “brief description of support practices” (p 477. Additional demographic questions addressed the years of experience of the respondent, undergraduate student enrollment of the university, and whether librarians held faculty rank. Main Results – The author measured Pearson correlation coefficients and found a positive correlation between the library scales and the HIPs. All three library scales displayed a moderately strong positive correlation between first-year seminars and experiences (HIP 1, common intellectual experiences (HIP 2, writing-intensive courses (HIP 4, undergraduate research (HIP 6, diversity and global learning (HIP 7, service learning and community-based learning (HIP 8, internships (HIP 9, and capstone courses and projects (HIP 10. The library collections scale and library facilities scale displayed a moderately strong correlation with learning communities (HIP 3 and collaborative assignments and projects (HIP 5. The library instruction scale displayed a strong positive correlation with HIP 3 and a very strong
Institute of Scientific and Technical Information of China (English)
陈敏伯
2011-01-01
本文旨在纠正一种在化学家中流传甚久的对统计数学中相关系数的错误理解.这种理解认为在数据拟合中单凭相关系数R大于某个人为指定值就可以判定数据拟合的优劣.%The misunderstanding in chemical community about the correlation coefficient R in statistical regression is pointed out and corrected. The misunderstanding has considered for a long time that the satisfactory of the linear regression can be judged by means of correlation coefficient solely.
Institute of Scientific and Technical Information of China (English)
王平
2015-01-01
研究高校各类课程之间的关联关系是信息化教学的手段之一，而分析课程成绩之间的相关性是研究高校课程关联关系的重要方法。针对传统的Pearson相关系数易于受到异常点影响的问题，提出一种基于鲁棒相关系数的成绩关联分析方法。该方法首先建立样本标准差的鲁棒估计器，在此基础上计算相关系数的鲁棒估计，最后将其用于不同课程成绩之间的相关性分析。%Study on the incidence relation among the various courses in colleges and universities is one of information⁃based teaching measures,and analysis of the correlation between course grades is one of the important methods of researching the incidence relation among courses. Aiming at the problem that the traditional Pearson correlation coefficient is influenced by outliers easily,a score correlation analytical method based on robust correlation coefficient is proposed. With the method,the ro⁃bust estimator of sample standard deviation is established. Based on this,the robust estimation of correlation coefficient is calcu⁃lated,which can be applied to correlation analysis between different courses.
2010-07-01
... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Illustration of the Minimum Limits for Correlation Coefficient for PM2.5 and PM10â2.5 Class II and III Methods C Figure C-4 to Subpart C of Part 53... Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-4 Figure C-4 to Subpart C of Part 53—Illustration...
Malinowski, Z.; Telejko, T.; Cebo-Rudnicka, A.; Szajding, A.; Rywotycki, M.; Hadała, B.
2016-09-01
The industrial rolling mills are equipped with systems for controlled water cooling of hot steel products. A cooling rate affects the final mechanical properties of steel which are strongly dependent on microstructure evolution processes. In case of water jets cooling the heat transfer boundary condition can be defined by the heat transfer coefficient. In the present study one and three dimensional heat conduction models have been employed in the inverse solution to heat transfer coefficient. The inconel plate has been heated to about 900oC and then cooled by one, two and six water jets. The plate temperature has been measured by 30 thermocouples. The heat transfer coefficient distributions at plate surface have been determined in time of cooling.
Covariance fitting of highly-correlated data in lattice QCD
Yoon, Boram; Jang, Yong-Chull; Jung, Chulwoo; Lee, Weonjong
2013-07-01
We address a frequently-asked question on the covariance fitting of highly-correlated data such as our B K data based on the SU(2) staggered chiral perturbation theory. Basically, the essence of the problem is that we do not have a fitting function accurate enough to fit extremely precise data. When eigenvalues of the covariance matrix are small, even a tiny error in the fitting function yields a large chi-square value and spoils the fitting procedure. We have applied a number of prescriptions available in the market, such as the cut-off method, modified covariance matrix method, and Bayesian method. We also propose a brand new method, the eigenmode shift (ES) method, which allows a full covariance fitting without modifying the covariance matrix at all. We provide a pedagogical example of data analysis in which the cut-off method manifestly fails in fitting, but the rest work well. In our case of the B K fitting, the diagonal approximation, the cut-off method, the ES method, and the Bayesian method work reasonably well in an engineering sense. However, interpreting the meaning of χ 2 is easier in the case of the ES method and the Bayesian method in a theoretical sense aesthetically. Hence, the ES method can be a useful alternative optional tool to check the systematic error caused by the covariance fitting procedure.