New Insights into Signed Path Coefficient Granger Causality Analysis.
Zhang, Jian; Li, Chong; Jiang, Tianzi
2016-01-01
Granger causality analysis, as a time series analysis technique derived from econometrics, has been applied in an ever-increasing number of publications in the field of neuroscience, including fMRI, EEG/MEG, and fNIRS. The present study mainly focuses on the validity of "signed path coefficient Granger causality," a Granger-causality-derived analysis method that has been adopted by many fMRI researches in the last few years. This method generally estimates the causality effect among the time series by an order-1 autoregression, and defines a positive or negative coefficient as an "excitatory" or "inhibitory" influence. In the current work we conducted a series of computations from resting-state fMRI data and simulation experiments to illustrate the signed path coefficient method was flawed and untenable, due to the fact that the autoregressive coefficients were not always consistent with the real causal relationships and this would inevitablely lead to erroneous conclusions. Overall our findings suggested that the applicability of this kind of causality analysis was rather limited, hence researchers should be more cautious in applying the signed path coefficient Granger causality to fMRI data to avoid misinterpretation.
New Insights into Signed Path Coefficient Granger Causality Analysis
Zhang, Jian; Li, Chong; Jiang, Tianzi
2016-01-01
Granger causality analysis, as a time series analysis technique derived from econometrics, has been applied in an ever-increasing number of publications in the field of neuroscience, including fMRI, EEG/MEG, and fNIRS. The present study mainly focuses on the validity of “signed path coefficient Granger causality,” a Granger-causality-derived analysis method that has been adopted by many fMRI researches in the last few years. This method generally estimates the causality effect among the time series by an order-1 autoregression, and defines a positive or negative coefficient as an “excitatory” or “inhibitory” influence. In the current work we conducted a series of computations from resting-state fMRI data and simulation experiments to illustrate the signed path coefficient method was flawed and untenable, due to the fact that the autoregressive coefficients were not always consistent with the real causal relationships and this would inevitablely lead to erroneous conclusions. Overall our findings suggested that the applicability of this kind of causality analysis was rather limited, hence researchers should be more cautious in applying the signed path coefficient Granger causality to fMRI data to avoid misinterpretation. PMID:27833547
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.
Debebe, Abel; Singh, Harijat; Tefera, Hailu
2014-01-01
This experiment was conducted at Debre Zeit and Akaki during 2004-2005 cropping season on F2-derived F4 bulk families of three crosses, viz, DZ-01-974 x DZ-01-2786, DZ-01-974 x DZ-Cr-37 and Alba x Kaye Murri. To estimate the correlations and path coefficients between yield and yield components, 63 F4 families were taken randomly from each of the three crosses. The 189 F4 families, five parents and two checks were space planted following in 14 x 14 simple lattice design. Study of associations among traits indicated that yield was positively associated with shoot biomass, harvest index, lodging index and panicle kernel weight at phenotypic level at Debre Zeit. At Akaki, yield had significant positive correlation with shoot biomass, harvest index, plant height, panicle length and panicle weight. At genotypic level, grain yield per plot exhibited positive association with harvest index, shoot biomass, lodging index and panicle kernel weight at Debre Zeit. By contrast, days to heading, days to maturity, plant height and panicle length showed negative association with yield. At Akaki, kernel yield per plot was positively correlated at genotypic level with all the traits considered where lodging index had the highest correlation followed by shoot biomass, panicle kernel weight and harvest index. Path coefficient analysis at both phenotypic and genotypic levels for both the locations suggested those shoot biomass and harvest indexes are the two important yield determining traits. These two traits might be useful in indirect selection for yield improvement in the material generated from the three crosses under consideration.
Snell, Mark K.
2007-07-14
The PANL software determines path through an Adversary Sequence Diagram (ASD) with minimum Probability of Interruption, P(I), given the ASD information and data about site detection, delay, and response force times. To accomplish this, the software generates each path through the ASD, then applies the Estimate of Adversary Sequence Interruption (EASI) methodology for calculating P(I) to each path, and keeps track of the path with the lowest P(I). Primary use is for training purposes during courses on physical security design. During such courses PANL will be used to demonstrate to students how more complex software codes are used by the US Department of Energy to determine the most-vulnerable paths and, where security needs improvement, how such codes can help determine physical security upgrades.
Path-counting formulas for generalized kinship coefficients and condensed identity coefficients.
Cheng, En; Ozsoyoglu, Z Meral
2014-01-01
An important computation on pedigree data is the calculation of condensed identity coefficients, which provide a complete description of the degree of relatedness of two individuals. The applications of condensed identity coefficients range from genetic counseling to disease tracking. Condensed identity coefficients can be computed using linear combinations of generalized kinship coefficients for two, three, four individuals, and two pairs of individuals and there are recursive formulas for computing those generalized kinship coefficients (Karigl, 1981). Path-counting formulas have been proposed for the (generalized) kinship coefficients for two (three) individuals but there have been no path-counting formulas for the other generalized kinship coefficients. It has also been shown that the computation of the (generalized) kinship coefficients for two (three) individuals using path-counting formulas is efficient for large pedigrees, together with path encoding schemes tailored for pedigree graphs. In this paper, we propose a framework for deriving path-counting formulas for generalized kinship coefficients. Then, we present the path-counting formulas for all generalized kinship coefficients for which there are recursive formulas and which are sufficient for computing condensed identity coefficients. We also perform experiments to compare the efficiency of our method with the recursive method for computing condensed identity coefficients on large pedigrees.
Path Flow Estimation Using Time Varying Coefficient State Space Model
NASA Astrophysics Data System (ADS)
Jou, Yow-Jen; Lan, Chien-Lun
2009-08-01
The dynamic path flow information is very crucial in the field of transportation operation and management, i.e., dynamic traffic assignment, scheduling plan, and signal timing. Time-dependent path information, which is important in many aspects, is nearly impossible to be obtained. Consequently, researchers have been seeking estimation methods for deriving valuable path flow information from less expensive traffic data, primarily link traffic counts of surveillance systems. This investigation considers a path flow estimation problem involving the time varying coefficient state space model, Gibbs sampler, and Kalman filter. Numerical examples with part of a real network of the Taipei Mass Rapid Transit with real O-D matrices is demonstrated to address the accuracy of proposed model. Results of this study show that this time-varying coefficient state space model is very effective in the estimation of path flow compared to time-invariant model.
NASA Astrophysics Data System (ADS)
Huang, Yunwei; Long, Mujun; Liu, Peng; Chen, Dengfu; Chen, Huabiao; Gui, Lintao; Liu, Tao; Yu, Sheng
2017-10-01
To quantitatively study the effects of partition coefficients, diffusion coefficients, and solidification paths on solute microsegregation, an analytical model was developed combined with the calculation of thermodynamic software FactSage. This model, applied with variational partition coefficients and temperature-dependent diffusion coefficients, is based on the Voller-Beckermann model and is extended to take into account the effects of multiple components and the peritectic phase transformation using FactSage. The predictions agree well with a range of measured data and the results of other numerical solutions. As the results indicate, the partition coefficients of solutes are functions of temperature and phase fraction during the solidification process, and the solute microsegregation increases significantly with decreasing partition coefficients. The calculations of solute microsegregation ratio ( C L/ C 0) in the interdendritic region are related to solidification paths. The microsegregation ratios of P and S increase as the initial C concentration increases, while they reduce with increasing initial C contents for solutes C and Si. Parameter sensitivity analysis was performed, and the results indicate that the solute microsegregation shows larger variation with partition coefficients and solidification paths than diffusion coefficients.
Path Analysis: A Brief Introduction.
ERIC Educational Resources Information Center
Carducci, Bernardo J.
Path analysis is presented as a technique that can be used to test on a priori model based on a theoretical conceptualization involving a network of selected variables. This being an introductory source, no previous knowledge of path analysis is assumed, although some understanding of the fundamentals of multiple regression analysis might be…
Interactive cutting path analysis programs
NASA Technical Reports Server (NTRS)
Weiner, J. M.; Williams, D. S.; Colley, S. R.
1975-01-01
The operation of numerically controlled machine tools is interactively simulated. Four programs were developed to graphically display the cutting paths for a Monarch lathe, Cintimatic mill, Strippit sheet metal punch, and the wiring path for a Standard wire wrap machine. These programs are run on a IMLAC PDS-ID graphic display system under the DOS-3 disk operating system. The cutting path analysis programs accept input via both paper tape and disk file.
An Introduction to Path Analysis
ERIC Educational Resources Information Center
Wolfe, Lee M.
1977-01-01
The analytical procedure of path analysis is described in terms of its use in nonexperimental settings in the social sciences. The description assumes a moderate statistical background on the part of the reader. (JKS)
Fidan, Barış; Umay, Ilknur
2015-01-01
Accurate signal-source and signal-reflector target localization tasks via mobile sensory units and wireless sensor networks (WSNs), including those for environmental monitoring via sensory UAVs, require precise knowledge of specific signal propagation properties of the environment, which are permittivity and path loss coefficients for the electromagnetic signal case. Thus, accurate estimation of these coefficients has significant importance for the accuracy of location estimates. In this paper, we propose a geometric cooperative technique to instantaneously estimate such coefficients, with details provided for received signal strength (RSS) and time-of-flight (TOF)-based range sensors. The proposed technique is integrated to a recursive least squares (RLS)-based adaptive localization scheme and an adaptive motion control law, to construct adaptive target localization and adaptive target tracking algorithms, respectively, that are robust to uncertainties in aforementioned environmental signal propagation coefficients. The efficiency of the proposed adaptive localization and tracking techniques are both mathematically analysed and verified via simulation experiments. PMID:26690441
Path-integral calculation of the third virial coefficient of quantum gases at low temperatures
Garberoglio, Giovanni; Harvey, Allan H.
2011-04-07
We derive path-integral expressions for the second and third virial coefficients of monatomic quantum gases. Unlike previous work that considered only Boltzmann statistics, we include exchange effects (Bose-Einstein or Fermi-Dirac statistics). We use state-of-the-art pair and three-body potentials to calculate the third virial coefficient of {sup 3}He and {sup 4}He in the temperature range 2.6-24.5561 K. We obtain uncertainties smaller than those of the limited experimental data. Inclusion of exchange effects is necessary to obtain accurate results below about 7 K.
Path-integral calculation of the third virial coefficient of quantum gases at low temperatures.
Garberoglio, Giovanni; Harvey, Allan H
2011-04-07
We derive path-integral expressions for the second and third virial coefficients of monatomic quantum gases. Unlike previous work that considered only Boltzmann statistics, we include exchange effects (Bose-Einstein or Fermi-Dirac statistics). We use state-of-the-art pair and three-body potentials to calculate the third virial coefficient of (3)He and (4)He in the temperature range 2.6-24.5561 K. We obtain uncertainties smaller than those of the limited experimental data. Inclusion of exchange effects is necessary to obtain accurate results below about 7 K.
Data analysis for Seebeck coefficient measurements
NASA Astrophysics Data System (ADS)
de Boor, J.; Müller, E.
2013-06-01
The Seebeck coefficient is one of the key quantities of thermoelectric materials and routinely measured in various laboratories. There are, however, several ways to calculate the Seebeck coefficient from the raw measurement data. We compare these different ways to extract the Seebeck coefficient, evaluate the accuracy of the results, and show methods to increase this accuracy. We furthermore point out experimental and data analysis parameters that can be used to evaluate the trustworthiness of the obtained result. The shown analysis can be used to find and minimize errors in the Seebeck coefficient measurement and therefore increase the reliability of the measured material properties.
Pathfinder: Visual Analysis of Paths in Graphs
Partl, C.; Gratzl, S.; Streit, M.; Wassermann, A. M.; Pfister, H.; Schmalstieg, D.; Lex, A.
2016-01-01
The analysis of paths in graphs is highly relevant in many domains. Typically, path-related tasks are performed in node-link layouts. Unfortunately, graph layouts often do not scale to the size of many real world networks. Also, many networks are multivariate, i.e., contain rich attribute sets associated with the nodes and edges. These attributes are often critical in judging paths, but directly visualizing attributes in a graph layout exacerbates the scalability problem. In this paper, we present visual analysis solutions dedicated to path-related tasks in large and highly multivariate graphs. We show that by focusing on paths, we can address the scalability problem of multivariate graph visualization, equipping analysts with a powerful tool to explore large graphs. We introduce Pathfinder (Figure 1), a technique that provides visual methods to query paths, while considering various constraints. The resulting set of paths is visualized in both a ranked list and as a node-link diagram. For the paths in the list, we display rich attribute data associated with nodes and edges, and the node-link diagram provides topological context. The paths can be ranked based on topological properties, such as path length or average node degree, and scores derived from attribute data. Pathfinder is designed to scale to graphs with tens of thousands of nodes and edges by employing strategies such as incremental query results. We demonstrate Pathfinder's fitness for use in scenarios with data from a coauthor network and biological pathways. PMID:27942090
Garberoglio, Giovanni; Jankowski, Piotr; Szalewicz, Krzysztof; Harvey, Allan H.
2014-07-28
We present a path-integral Monte Carlo procedure for the fully quantum calculation of the second molecular virial coefficient accounting for intramolecular flexibility. This method is applied to molecular hydrogen (H{sub 2}) and deuterium (D{sub 2}) in the temperature range 15–2000 K, showing that the effect of molecular flexibility is not negligible. Our results are in good agreement with experimental data, as well as with virials given by recent empirical equations of state, although some discrepancies are observed for H{sub 2} between 100 and 200 K.
NASA Astrophysics Data System (ADS)
Garberoglio, Giovanni; Jankowski, Piotr; Szalewicz, Krzysztof; Harvey, Allan H.
2014-07-01
We present a path-integral Monte Carlo procedure for the fully quantum calculation of the second molecular virial coefficient accounting for intramolecular flexibility. This method is applied to molecular hydrogen (H2) and deuterium (D2) in the temperature range 15-2000 K, showing that the effect of molecular flexibility is not negligible. Our results are in good agreement with experimental data, as well as with virials given by recent empirical equations of state, although some discrepancies are observed for H2 between 100 and 200 K.
Garberoglio, Giovanni; Jankowski, Piotr; Szalewicz, Krzysztof; Harvey, Allan H
2014-07-28
We present a path-integral Monte Carlo procedure for the fully quantum calculation of the second molecular virial coefficient accounting for intramolecular flexibility. This method is applied to molecular hydrogen (H2) and deuterium (D2) in the temperature range 15-2000 K, showing that the effect of molecular flexibility is not negligible. Our results are in good agreement with experimental data, as well as with virials given by recent empirical equations of state, although some discrepancies are observed for H2 between 100 and 200 K.
Meta-Analysis of Coefficient Alpha
ERIC Educational Resources Information Center
Rodriguez, Michael C.; Maeda, Yukiko
2006-01-01
The meta-analysis of coefficient alpha across many studies is becoming more common in psychology by a methodology labeled reliability generalization. Existing reliability generalization studies have not used the sampling distribution of coefficient alpha for precision weighting and other common meta-analytic procedures. A framework is provided for…
Conditions for transmission path analysis in energy distribution models
NASA Astrophysics Data System (ADS)
Aragonès, Àngels; Guasch, Oriol
2016-02-01
In this work, we explore under which conditions transmission path analysis (TPA) developed for statistical energy analysis (SEA) can be applied to the less restrictive energy distribution (ED) models. It is shown that TPA can be extended without problems to proper-SEA systems whereas the situation is not so clear for quasi-SEA systems. In the general case, it has been found that a TPA can always be performed on an ED model if its inverse influence energy coefficient (EIC) matrix turns to have negative off-diagonal entries. If this condition is satisfied, it can be shown that the inverse EIC matrix automatically becomes an M-matrix. An ED graph can then be defined for it and use can be made of graph theory ranking path algorithms, previously developed for SEA systems, to classify dominant paths in ED models. A small mechanical system consisting of connected plates has been used to illustrate some of the exposed theoretical results.
Soccer ball lift coefficients via trajectory analysis
NASA Astrophysics Data System (ADS)
Goff, John Eric; Carré, Matt J.
2010-07-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.
Bayesian Meta-Analysis of Coefficient Alpha
ERIC Educational Resources Information Center
Brannick, Michael T.; Zhang, Nanhua
2013-01-01
The current paper describes and illustrates a Bayesian approach to the meta-analysis of coefficient alpha. Alpha is the most commonly used estimate of the reliability or consistency (freedom from measurement error) for educational and psychological measures. The conventional approach to meta-analysis uses inverse variance weights to combine…
Bayesian Meta-Analysis of Coefficient Alpha
ERIC Educational Resources Information Center
Brannick, Michael T.; Zhang, Nanhua
2013-01-01
The current paper describes and illustrates a Bayesian approach to the meta-analysis of coefficient alpha. Alpha is the most commonly used estimate of the reliability or consistency (freedom from measurement error) for educational and psychological measures. The conventional approach to meta-analysis uses inverse variance weights to combine…
Zero temperature coefficient of resistance of the electrical-breakdown path in ultrathin hafnia
NASA Astrophysics Data System (ADS)
Zhang, H. Z.; Ang, D. S.
2017-09-01
The recent widespread attention on the use of the non-volatile resistance switching property of a microscopic oxide region after electrical breakdown for memory applications has prompted basic interest in the conduction properties of the breakdown region. Here, we report an interesting crossover from a negative to a positive temperature dependence of the resistance of a breakdown region in ultrathin hafnia as the applied voltage is increased. As a consequence, a near-zero temperature coefficient of resistance is obtained at the crossover voltage. The behavior may be modeled by (1) a tunneling-limited transport involving two farthest-spaced defects along the conduction path at low voltage and (2) a subsequent transition to a scattering-limited transport after the barrier is overcome by a larger applied voltage.
A taxonomy of integral reaction path analysis
Grcar, Joseph F.; Day, Marcus S.; Bell, John B.
2004-12-23
W. C. Gardiner observed that achieving understanding through combustion modeling is limited by the ability to recognize the implications of what has been computed and to draw conclusions about the elementary steps underlying the reaction mechanism. This difficulty can be overcome in part by making better use of reaction path analysis in the context of multidimensional flame simulations. Following a survey of current practice, an integral reaction flux is formulated in terms of conserved scalars that can be calculated in a fully automated way. Conditional analyses are then introduced, and a taxonomy for bidirectional path analysis is explored. Many examples illustrate the resulting path analysis and uncover some new results about nonpremixed methane-air laminar jets.
Path Analysis: A Link between Family Theory and Reseach.
ERIC Educational Resources Information Center
Rank, Mark R.; Sabatelli, Ronald M.
This paper discusses path analysis and the applicability of this methodology to the field of family studies. The statistical assumptions made in path analysis are presented along with a description of the two types of models within path analysis, i.e., recursive and non-recursive. Methods of calculating in the path model and the advantages of…
The Use of Path Analysis in Program Evaluation. No. 12.
ERIC Educational Resources Information Center
Smith, Nick L.; Murray, Stephen L.
Path analysis, a technique related to multiple regression analysis is used for ascribing causal relationships among variables. Path analysis involves the construction of explicitly formulated causal models and makes the reasoning explicit in the form of path diagrams and structural equations. Regression analysis is then used to construct path…
Soccer Ball Lift Coefficients via Trajectory Analysis
ERIC Educational Resources Information Center
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
Soccer Ball Lift Coefficients via Trajectory Analysis
ERIC Educational Resources Information Center
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
Statechart Analysis with Symbolic PathFinder
NASA Technical Reports Server (NTRS)
Pasareanu, Corina S.
2012-01-01
We report here on our on-going work that addresses the automated analysis and test case generation for software systems modeled using multiple Statechart formalisms. The work is motivated by large programs such as NASA Exploration, that involve multiple systems that interact via safety-critical protocols and are designed with different Statechart variants. To verify these safety-critical systems, we have developed Polyglot, a framework for modeling and analysis of model-based software written using different Statechart formalisms. Polyglot uses a common intermediate representation with customizable Statechart semantics and leverages the analysis and test generation capabilities of the Symbolic PathFinder tool. Polyglot is used as follows: First, the structure of the Statechart model (expressed in Matlab Stateflow or Rational Rhapsody) is translated into a common intermediate representation (IR). The IR is then translated into Java code that represents the structure of the model. The semantics are provided as "pluggable" modules.
Cole, David A; Preacher, Kristopher J
2014-06-01
Despite clear evidence that manifest variable path analysis requires highly reliable measures, path analyses with fallible measures are commonplace even in premier journals. Using fallible measures in path analysis can cause several serious problems: (a) As measurement error pervades a given data set, many path coefficients may be either over- or underestimated. (b) Extensive measurement error diminishes power and can prevent invalid models from being rejected. (c) Even a little measurement error can cause valid models to appear invalid. (d) Differential measurement error in various parts of a model can change the substantive conclusions that derive from path analysis. (e) All of these problems become increasingly serious and intractable as models become more complex. Methods to prevent and correct these problems are reviewed. The conclusion is that researchers should use more reliable measures (or correct for measurement error in the measures they do use), obtain multiple measures for use in latent variable modeling, and test simpler models containing fewer variables.
Performance Analysis of Path Planning Modeling
NASA Astrophysics Data System (ADS)
Wang, Zhirui; Li, Shuanghong; Zhang, Ying; Du, Qiaoling
Ant colony system (ACS) algorithm was applied to the path planning for the robot. In the same working environment, path planning based on MAKLINK graph theory and Voronoi diagram were simulated and compared. MAKLINK graph theory is appropriate to apply to precise searching in small-scale district, and Voronoi diagram is suitable for fast path planning in a large area.
Adaptive path planning: Algorithm and analysis
Chen, Pang C.
1993-03-01
Path planning has to be fast to support real-time robot programming. Unfortunately, current planning techniques are still too slow to be effective, as they often require several minutes, if not hours of computation. To alleviate this problem, we present a learning algorithm that uses past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, an evolving sparse network of useful subgoals is learned to support faster planning. The algorithm is suitable for both stationary and incrementally-changing environments. To analyze our algorithm, we use a previously developed stochastic model that quantifies experience utility. Using this model, we characterize the situations in which the adaptive planner is useful, and provide quantitative bounds to predict its behavior. The results are demonstrated with problems in manipulator planning. Our algorithm and analysis are sufficiently general that they may also be applied to task planning or other planning domains in which experience is useful.
NASA Technical Reports Server (NTRS)
Rinsland, Curtis P.; Smith, Mary Ann H.; Goldman, Aaron; Malathy Devi, V.
1991-01-01
Lorentz air-broadening coefficients and relative intensities have been measured for forty-three lines in the pure rotational band and twenty lines in the nu2 band of H2O-16 between 800 and 1150/cm. The results were derived from analysis of nine 0.017/cm-resolution atmospheric absorption spectra recorded over horizontal paths of 0.5-1.5 km with the McMath Fourier transform spectrometer and main solar telescope operated on Kitt Peak by the National Solar Observatory. A nonlinear least-squares spectral fitting technique was used in the spectral analysis. The results are compared with previous measurements and calculations. In most cases, the measured pressure-broadening coefficients and intensities are significantly different from the values in the 1986 HITRAN line parameters compilation.
NASA Astrophysics Data System (ADS)
Imaoka, Haruna; Kinugawa, Kenichi
2017-03-01
Thermal conductivity, shear viscosity, and bulk viscosity of normal liquid 4He at 1.7-4.0 K are calculated using path integral centroid molecular dynamics (CMD) simulations. The calculated thermal conductivity and shear viscosity above lambda transition temperature are on the same order of magnitude as experimental values, while the agreement of shear viscosity is better. Above 2.3 K the CMD well reproduces the temperature dependences of isochoric shear viscosity and of the time integral of the energy current and off-diagonal stress tensor correlation functions. The calculated bulk viscosity, not known in experiments, is several times larger than shear viscosity.
A new coefficient of concordance with applications to biosignal analysis
NASA Astrophysics Data System (ADS)
Xu, Weichao; Chen, Zhaoguo; Liu, Wenqing
2015-12-01
In this paper we propose a novel concordance coefficients called Order Statistics Concordance Coefficients based on order statistics and Pearson's Product Moment Correlation Coefficient. For comparison, we also construct other three similar index based on Average Pearson's Product Moment Correlation Coefficient, Kendall's Concordance Coefficients, Average Kendall's tau. We propose Multivariate Normal Model to estimate the correlation coefficient, Linear Model and Nonlinear Model to model the linear and nonlinear association between multichannel signals, And we also apply the concordance coefficients to biosignal analysis developed a new organizational index for quantifying organization of AF. Statistical evidences suggest that (a) Order Statistics Concordance Coefficients have better robust than other three index; (b) capable of distinguishing fibrillatory rhythms from nonfibrillatory rhythms, such as Atiral flutter; (c) can reflect the effectiveness of adenosine, a drug commonly used during electrophysiological procedures; and (d) perform better than other three concordance coefficients.
Review of analysis methods for rotating systems with periodic coefficients
NASA Technical Reports Server (NTRS)
Dugundji, J.; Wendell, J. H.
1981-01-01
Two of the more common procedures for analyzing the stability and forced response of equations with periodic coefficients are reviewed: the use of Floquet methods, and the use of multiblade coordinate and harmonic balance methods. The analysis procedures of these periodic coefficient systems are compared with those of the more familiar constant coefficient systems.
A Statistical Analysis of YORP Coefficients
NASA Astrophysics Data System (ADS)
McMahon, Jay W.; Scheeres, D.
2013-10-01
The YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect is theorized to be a major factor in the evolution of small asteroids (<10 km) in the near-Earth and main belt populations. YORP torques, which originate from absorbed sunlight and subsequent thermal radiation, causes secular changes in an asteroid's spin rate and spin vector orientation (e.g. Rubincam, Journal of Geophysical Research, 1995). This in turn controls the magnitude and direction of the Yarkovsky effect, which causes a drift in an asteroid's heliocentric semi-major axis (Vokrouhlicky and Farinella, Nature, 2000). YORP is also thought to be responsible for the creation of multiple asteroid systems and asteroid pairs through the process of rotational fission (Pravec et al, Nature, 2010). Despite the fact that the YORP effect has been measured on several asteroids (e.g. Taylor et al, Science, 2007 and Kaasalainen et al, Nature, 2007), it has proven very difficult to predict the effect accurately from a shape model due to the sensitivity of the YORP coefficients to shape changes (Statler, Icarus, 2009). This has been especially troublesome for Itokawa, for which a very detailed shape model is available (Scheeres et al, Icarus 2007; Breiter et al, Astronomy & Astrophysics, 2009). In this study, we compute the YORP coefficients for a number asteroids with detailed shape models available on the PDS-SBN. We then statistically perturb the asteroid shapes at the same resolution, creating a family of YORP coefficients for each shape. Next, we analyze the change in YORP coefficients between a shape model of accuracy obtainable from radar with one including small-scale topography on the surface as was observed on Itokawa. The combination of these families of coefficients will effectively give error bars on our knowledge of the YORP coefficients given a shape model of some accuracy. Finally, we discuss the statistical effect of boulder and craters, and the modification of these results due to recent studies on
THE STUDY OF COLLEGE ENVIRONMENTS USING PATH ANALYSIS.
ERIC Educational Resources Information Center
WERTS, CHARLES E.
THIS STUDY ATTEMPTS TO DEMONSTRATE THAT PATH ANALYSIS IS A VALUABLE TOOL FOR INTERPRETING CORRELATIONS IN A CAUSAL SENSE. PATH ANALYSIS IS APPLIED TO A NONEXPERIMENTAL, PANEL SURVEY IN AN EFFORT TO DETERMINE WHETHER THE MORE SELECTIVE OR LESS SELECTIVE COLLEGES HAD A DIFFERENTIAL IMPACT ON THE EDUCATIONAL PLANS OF THEIR STUDENTS. THE PROBLEM IS TO…
Spectral analysis of the VLBI pole path
NASA Astrophysics Data System (ADS)
Zuberi, Midhat; Smylie, Doug E.
2009-12-01
Modern observations of polar motion, using techniques such as Very Long Baseline Interferometry (VLBI), have reduced error levels by as much as three orders of magnitude, compared to classical astronometric methods. Here we focus on VLBI observations which are characteristically unequally spaced. We develop a very effective method of spectral analysis for unequally spaced time sequences. First, the least squares fit to the representation of the sequence by the Discrete Fourier Transform (DFT) is calculated, weighting the observations by the inverse square of the accompanying standard error. The coefficient matrix of the normal equations of this fit is nearly singular. It is subjected to a Singular Value Decomposition (SVD). In the usual application of SVD singular values are eliminated in order to improve the stability of the numerical system but no criterion is given for how many singular values to eliminate. To overcome this shortcoming, we introduce the Parseval condition which relates the mean square in the time domain to that in the frequency domain. Singular values are eliminated until Parseval's theorem is satisfied. Typically, the mean square in the frequency domain is many orders of magnitude too large. As singular values are eliminated, starting with the smallest and working upward, the mean square in the frequency domain appears to decrease monotonically until the Parseval relation is satisfied. Once the DFTs are found, spectral analysis and the estimation of confidence intervals proceed in the standard way. We perform a spectral analysis of the polar motion on 24.5 years of observations by using a Welch Overlapping Segment Analysis (WOSA) with four record segments of 14-year length with 75% overlap. Parameters of the Chandler wobble resonance are found as well as a detailed spectrum.
Guenole, Nigel; Brown, Anna
2014-01-01
We report a Monte Carlo study examining the effects of two strategies for handling measurement non-invariance – modeling and ignoring non-invariant items – on structural regression coefficients between latent variables measured with item response theory models for categorical indicators. These strategies were examined across four levels and three types of non-invariance – non-invariant loadings, non-invariant thresholds, and combined non-invariance on loadings and thresholds – in simple, partial, mediated and moderated regression models where the non-invariant latent variable occupied predictor, mediator, and criterion positions in the structural regression models. When non-invariance is ignored in the latent predictor, the focal group regression parameters are biased in the opposite direction to the difference in loadings and thresholds relative to the referent group (i.e., lower loadings and thresholds for the focal group lead to overestimated regression parameters). With criterion non-invariance, the focal group regression parameters are biased in the same direction as the difference in loadings and thresholds relative to the referent group. While unacceptable levels of parameter bias were confined to the focal group, bias occurred at considerably lower levels of ignored non-invariance than was previously recognized in referent and focal groups. PMID:25278911
NASA Astrophysics Data System (ADS)
Subramanian, Ramachandran; Schultz, Andrew J.; Kofke, David A.
2017-03-01
We develop an orientation sampling algorithm for rigid diatomic molecules, which allows direct generation of rings of images used for path-integral calculation of nuclear quantum effects. The algorithm treats the diatomic molecule as two independent atoms as opposed to one (quantum) rigid rotor. Configurations are generated according to a solvable approximate distribution that is corrected via the acceptance decision of the Monte Carlo trial. Unlike alternative methods that treat the systems as a quantum rotor, this atom-based approach is better suited for generalization to multi-atomic (more than two atoms) and flexible molecules. We have applied this algorithm in combination with some of the latest ab initio potentials of rigid H2 to compute fully quantum second virial coefficients, for which we observe excellent agreement with both experimental and simulation data from the literature.
Folded-path optical analysis gas cell
Carangelo, R.M.; Wright, D.D.
1995-08-08
A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal foci coincidence and thereby to increase the radiation energy throughput characteristic of the cell. 10 figs.
An analysis of running skyline load path.
Ward W. Carson; Charles N. Mann
1971-01-01
This paper is intended for those who wish to prepare an algorithm to determine the load path of a running skyline. The mathematics of a simplified approach to this running skyline design problem are presented. The approach employs assumptions which reduce the complexity of the problem to the point where it can be solved on desk-top computers of limited capacities. The...
Folded-path optical analysis gas cell
Carangelo, Robert M.; Wright, David D.
1995-01-01
A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal focii coincidence and thereby to increase the radiation energy throughput characteristic of the cell.
Analysis of a heat transfer device for measuring film coefficients
NASA Technical Reports Server (NTRS)
Medrow, R. A.; Johnson, R. L.; Loomis, W. R.; Wedeven, L. D.
1975-01-01
A heat transfer device consisting of a heated rotating cylinder in a bath was analyzed for its effectiveness to determine heat transfer coefficient of fluids. A time dependent analysis shows that the performance is insensitive to the value of heat transfer coefficient with the given rig configuration.
NASA Astrophysics Data System (ADS)
Dave, Prashant; Bhushan, Mani; Venkataraman, Chandra
2016-04-01
Aerosols can modulate variability of Indian summer monsoon by perturbing the radiative balance of the atmosphere, affecting the land-ocean processes and altering the cloud-microphysics at varying spatio-temporal scale, ranging from fast (less than a day) to slow (months) temporal effects. In the literature, overall interaction between AOD and Precipitation was quantified as correlation coefficients (Ramchandran and Kedia, 2013; Gryspeerdt et al., 2012; Gryspeerdt et al., 2014), however the segregation of the interaction was required to better understand the presence/absence of pathway mediated through changes in cloud-microphysics and atmospheric stability. In this work, effects of aerosols on precipitation, mediated through changes in cloud-microphysics and atmospheric stability, on daily time-scales, are studied and quantified using coincident observational data of aerosols, clouds and rainfall, using Path-analysis (Wright, 1969). MODIS, ERA-interim and IMD data-sets for years 2000-2009 for Aerosol optical depth (AOD), Column water vapour (CWV), Cloud droplet effective radius (CDERL), Convective available potential energy (CAPE) and Precipitation, over Indian region were used for the analysis. Cause-effect model was built to validate and quantify the effects of AOD on precipitation, mediated through CDERL and CAPE. To contrast cause-effect mechanism in presence and absence of aerosol fields, high AOD-low Precipitation and low AOD-low Precipitation clusters were formed. Cluster-averaged time series were used to calculate the lagged correlation (AOD leading) and provided as input to Path-analysis. "AOD-CDERL-Precipitation" and "AOD-CAPE-Precipitation" pathways were found to be statistically significant for high AOD-low Precipitation clusters while both were absent for low AOD-low Precipitation clusters, for years 2003 and 2004. For other years statistically significant pathway between AOD and Precipitation could not be found. In "AOD-CDERL-Precipitation" pathway
Vibration Analysis of a Split Path Gearbox
NASA Technical Reports Server (NTRS)
Krantz, Timothy L.; Rashidi, Majid
1995-01-01
Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.
[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.
PathVisio 3: An Extendable Pathway Analysis Toolbox
Kutmon, Martina; van Iersel, Martijn P.; Bohler, Anwesha; Kelder, Thomas; Nunes, Nuno; Pico, Alexander R.; Evelo, Chris T.
2015-01-01
PathVisio is a commonly used pathway editor, visualization and analysis software. Biological pathways have been used by biologists for many years to describe the detailed steps in biological processes. Those powerful, visual representations help researchers to better understand, share and discuss knowledge. Since the first publication of PathVisio in 2008, the original paper was cited more than 170 times and PathVisio was used in many different biological studies. As an online editor PathVisio is also integrated in the community curated pathway database WikiPathways. Here we present the third version of PathVisio with the newest additions and improvements of the application. The core features of PathVisio are pathway drawing, advanced data visualization and pathway statistics. Additionally, PathVisio 3 introduces a new powerful extension systems that allows other developers to contribute additional functionality in form of plugins without changing the core application. PathVisio can be downloaded from http://www.pathvisio.org and in 2014 PathVisio 3 has been downloaded over 5,500 times. There are already more than 15 plugins available in the central plugin repository. PathVisio is a freely available, open-source tool published under the Apache 2.0 license (http://www.apache.org/licenses/LICENSE-2.0). It is implemented in Java and thus runs on all major operating systems. The code repository is available at http://svn.bigcat.unimaas.nl/pathvisio. The support mailing list for users is available on https://groups.google.com/forum/#!forum/wikipathways-discuss and for developers on https://groups.google.com/forum/#!forum/wikipathways-devel. PMID:25706687
Seismic refraction analysis: the path forward
Haines, Seth S.; Zelt, Colin; Doll, William
2012-01-01
Seismic Refraction Methods: Unleashing the Potential and Understanding the Limitations; Tucson, Arizona, 29 March 2012 A workshop focused on seismic refraction methods took place on 29 May 2012, associated with the 2012 Symposium on the Application of Geophysics to Engineering and Environmental Problems. This workshop was convened to assess the current state of the science and discuss paths forward, with a primary focus on near-surface problems but with an eye on all applications. The agenda included talks on these topics from a number of experts interspersed with discussion and a dedicated discussion period to finish the day. Discussion proved lively at times, and workshop participants delved into many topics central to seismic refraction work.
Nonlinear reaction coordinate analysis in the reweighted path ensemble
NASA Astrophysics Data System (ADS)
Lechner, Wolfgang; Rogal, Jutta; Juraszek, Jarek; Ensing, Bernd; Bolhuis, Peter G.
2010-11-01
We present a flexible nonlinear reaction coordinate analysis method for the transition path ensemble based on the likelihood maximization approach developed by Peters and Trout [J. Chem. Phys. 125, 054108 (2006)]. By parametrizing the reaction coordinate by a string of images in a collective variable space, we can optimize the likelihood that the string correctly models the committor data obtained from a path sampling simulation. The collective variable space with the maximum likelihood is considered to contain the best description of the reaction. The use of the reweighted path ensemble [J. Rogal et al., J. Chem. Phys. 133, 174109 (2010)] allows a complete reaction coordinate description from the initial to the final state. We illustrate the method on a z-shaped two-dimensional potential. While developed for use with path sampling, this analysis method can also be applied to regular molecular dynamics trajectories.
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.
Path analysis: A model for the development of scientific reasoning abilities in adolescents
NASA Astrophysics Data System (ADS)
Stuessy, Carol L.
A model was formulated and tested for the development of scientific reasoning abilities in adolescents. Piagetian theory provided the framework for choosing potential determinants of the dependent variable, scientific reasoning abilities. A model reflecting hypothesized causal relationships among determinants and with the dependent variable was developed a priori on the basis of theoretical and substantive reasoning. The hypothesized model was tested and revised using path analysis. Data from intact classes of middle-school (n = 101) and high-school (n = 89) students from an upper-middle-class suburb of a midwestern city revealed significant (p < 0.05) path coefficients for these variables and scientific reasoning abilities: age, I.Q., field dependence-independence, and experience. A path from locus of control to scientific reasoning abilities through field dependence-independence was also statistically significant. The revised model explained 61 percent of the variance in scientific reasoning abilities.
Water maze swim path analysis based on tracking coordinates.
Korz, Volker
2006-08-01
In the Morris water maze, a task widely used to study spatial learning and memory in laboratory rodents, several parameters are employed to estimate cognitive abilities of animals by analyzing their swim path characteristics. An isolated view based on any one of these parameters is not always satisfactory, so multivariate procedures (factor analyses) are used to weight the parameters in context with the others. This method sheds light on some subtle differences in experimental animals' spatial memories or strategies. However, this approach has some subjective problems, because the definition of the parameters depends on the experimenter's opinion of appropriate measures; therefore, we suggest a bottom-up rather than a top-down analysis of swim paths by means of spatial coordinates. In the present study, swim paths were normalized to 100-element vectors and then subjected to a principal components analysis. Swim paths could be sufficiently described in terms of only three components, each of which accounted for specific characteristics of the trajectories. We found significant differences in swim path patterns between test groups of rats that could not be discriminated via standard water maze parameters. Thus, the components can be related to different aspects of spatial cognition not detectable by commonly used parameters.
Introduction and application of the multiscale coefficient of variation analysis.
Abney, Drew H; Kello, Christopher T; Balasubramaniam, Ramesh
2016-09-20
Quantifying how patterns of behavior relate across multiple levels of measurement typically requires long time series for reliable parameter estimation. We describe a novel analysis that estimates patterns of variability across multiple scales of analysis suitable for time series of short duration. The multiscale coefficient of variation (MSCV) measures the distance between local coefficient of variation estimates within particular time windows and the overall coefficient of variation across all time samples. We first describe the MSCV analysis and provide an example analytical protocol with corresponding MATLAB implementation and code. Next, we present a simulation study testing the new analysis using time series generated by ARFIMA models that span white noise, short-term and long-term correlations. The MSCV analysis was observed to be sensitive to specific parameters of ARFIMA models varying in the type of temporal structure and time series length. We then apply the MSCV analysis to short time series of speech phrases and musical themes to show commonalities in multiscale structure. The simulation and application studies provide evidence that the MSCV analysis can discriminate between time series varying in multiscale structure and length.
Path Similarity Analysis: A Method for Quantifying Macromolecular Pathways
Seyler, Sean L.; Kumar, Avishek; Thorpe, M. F.; Beckstein, Oliver
2015-01-01
Diverse classes of proteins function through large-scale conformational changes and various sophisticated computational algorithms have been proposed to enhance sampling of these macromolecular transition paths. Because such paths are curves in a high-dimensional space, it has been difficult to quantitatively compare multiple paths, a necessary prerequisite to, for instance, assess the quality of different algorithms. We introduce a method named Path Similarity Analysis (PSA) that enables us to quantify the similarity between two arbitrary paths and extract the atomic-scale determinants responsible for their differences. PSA utilizes the full information available in 3N-dimensional configuration space trajectories by employing the Hausdorff or Fréchet metrics (adopted from computational geometry) to quantify the degree of similarity between piecewise-linear curves. It thus completely avoids relying on projections into low dimensional spaces, as used in traditional approaches. To elucidate the principles of PSA, we quantified the effect of path roughness induced by thermal fluctuations using a toy model system. Using, as an example, the closed-to-open transitions of the enzyme adenylate kinase (AdK) in its substrate-free form, we compared a range of protein transition path-generating algorithms. Molecular dynamics-based dynamic importance sampling (DIMS) MD and targeted MD (TMD) and the purely geometric FRODA (Framework Rigidity Optimized Dynamics Algorithm) were tested along with seven other methods publicly available on servers, including several based on the popular elastic network model (ENM). PSA with clustering revealed that paths produced by a given method are more similar to each other than to those from another method and, for instance, that the ENM-based methods produced relatively similar paths. PSA applied to ensembles of DIMS MD and FRODA trajectories of the conformational transition of diphtheria toxin, a particularly challenging example, showed that
Path Analysis Tests of Theoretical Models of Children's Memory Performance
ERIC Educational Resources Information Center
DeMarie, Darlene; Miller, Patricia H.; Ferron, John; Cunningham, Walter R.
2004-01-01
Path analysis was used to test theoretical models of relations among variables known to predict differences in children's memory--strategies, capacity, and metamemory. Children in kindergarten to fourth grade (chronological ages 5 to 11) performed different memory tasks. Several strategies (i.e., sorting, clustering, rehearsal, and self-testing)…
Quantifying tight-gas sandstone permeability via critical path analysis
USDA-ARS?s Scientific Manuscript database
Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, especially in spatially complex rocks. In this letter, we apply critical path analysis (CPA) to estimate perm...
Establishing a Causal Model for Bloom's Taxonomy through Path Analysis.
ERIC Educational Resources Information Center
O'Hara, Takeshi; And Others
Path analysis was used to reanalyze Kropp and Stoker's data from tests designed to evaluate Bloom's taxonomy of educational objectives in the cognitive domain. Scores for 1,128 students in grades nine through twelve were analyzed separately by grade level for four content areas on six taxonomic levels. A measure of general ability was also…
Start and Stop Rules for Exploratory Path Analysis.
ERIC Educational Resources Information Center
Shipley, Bill
2002-01-01
Describes a method for choosing rejection probabilities for the tests of independence that are used in constraint-based algorithms of exploratory path analysis. The method consists of generating a Markov or semi-Markov model from the equivalence class represented by a partial ancestral graph and then testing the d-separation implications. (SLD)
Establishing a Causal Model for Bloom's Taxonomy through Path Analysis.
ERIC Educational Resources Information Center
O'Hara, Takeshi; And Others
Path analysis was used to reanalyze Kropp and Stoker's data from tests designed to evaluate Bloom's taxonomy of educational objectives in the cognitive domain. Scores for 1,128 students in grades nine through twelve were analyzed separately by grade level for four content areas on six taxonomic levels. A measure of general ability was also…
Du, Junli; Yuan, Zhifa; Ma, Ziwei; Song, Jiuzhou; Xie, Xiaoli; Chen, Yulin
2014-07-29
The dynamic impact approach (DIA) represents an alternative to overrepresentation analysis (ORA) for functional analysis of time-course experiments or those involving multiple treatments. The DIA can be used to estimate the biological impact of the differentially expressed genes (DEGs) associated with particular biological functions, for example, as represented by the Kyoto encyclopedia of genes and genomes (KEGG) annotations. However, the DIA does not take into account the correlated dependence structure of the KEGG pathway hierarchy. We have developed herein a path analysis model (KEGG-PATH) to subdivide the total effect of each KEGG pathway into the direct effect and indirect effect by taking into account not only each KEGG pathway itself, but also the correlation with its related pathways. In addition, this work also attempts to preliminarily estimate the impact direction of each KEGG pathway by a gradient analysis method from principal component analysis (PCA). As a result, the advantage of the KEGG-PATH model is demonstrated through the functional analysis of the bovine mammary transcriptome during lactation.
Comprehensive analysis of the optical Kerr coefficient of graphene
Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo
2016-08-25
We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition,more » self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.« less
Comprehensive analysis of the optical Kerr coefficient of graphene
Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo
2016-08-25
We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition, self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.
Comprehensive analysis of the optical Kerr coefficient of graphene
NASA Astrophysics Data System (ADS)
Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo
2016-08-01
We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S -matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition, self-coupling, and quadratic ac Stark effect. We also present a comparison of our theory with recent experimental and theoretical results.
Symbolic observability coefficients for univariate and multivariate analysis
NASA Astrophysics Data System (ADS)
Letellier, Christophe; Aguirre, Luis A.
2009-06-01
In practical problems, the observability of a system not only depends on the choice of observable(s) but also on the space which is reconstructed. In fact starting from a given set of observables, the reconstructed space is not unique, since the dimension can be varied and, in the case of multivariate measurement functions, there are various ways to combine the measured observables. Using a graphical approach recently introduced, we analytically compute symbolic observability coefficients which allow to choose from the system equations the best observable, in the case of scalar reconstructions, and the best way to combine the observables in the case of multivariate reconstructions. It is shown how the proposed coefficients are also helpful for analysis in higher dimension.
Comprehensive analysis of the optical Kerr coefficient of graphene
Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo
2016-08-25
We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition, self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.
Correlation and path analysis of biomass sorghum production.
Vendruscolo, T P S; Barelli, M A A; Castrillon, M A S; da Silva, R S; de Oliveira, F T; Corrêa, C L; Zago, B W; Tardin, F D
2016-12-23
Sorghum biomass is an interesting raw material for bioenergy production due to its versatility, potential of being a renewable energy source, and low-cost of production. The objective of this study was to evaluate the genetic variability of biomass sorghum genotypes and to estimate genotypic, phenotypic, and environmental correlations, and direct and indirect effects of seven agronomic traits through path analysis. Thirty-four biomass sorghum genotypes and two forage sorghum genotypes were cultivated in a randomized block design with three replicates. The following morpho-agronomic traits were evaluated: flowering date, stem diameter, number of stems, plant height, number of leaves, green mass production, and dry matter production. There were significant differences at the 1% level for all traits. The highest genotypic correlation was found between the traits green mass production and dry matter production. The path analysis demonstrated that green mass production and number of leaves can assist in the selection of dry matter production.
Path analysis of risk factors leading to premature birth.
Fields, S J; Livshits, G; Sirotta, L; Merlob, P
1996-01-01
The present study tested whether various sociodemographic, anthropometric, behavioral, and medical/physiological factors act in a direct or indirect manner on the risk of prematurity using path analysis on a sample of Israeli births. The path model shows that medical complications, primarily toxemia, chorioammionitis, and a previous low birth weight delivery directly and significantly act on the risk of prematurity as do low maternal pregnancy weight gain and ethnicity. Other medical complications, including chronic hypertension, preclampsia, and placental abruption, although significantly correlated with prematurity, act indirectly on prematurity through toxemia. The model further shows that the commonly accepted sociodemographic, anthropometric, and behavioral risk factors act by modifying the development of medical complications that lead to prematurity as opposed to having a direct effect on premature delivery. © 1996 Wiley-Liss, Inc. Copyright © 1996 Wiley-Liss, Inc.
Behavior analysis, mentalism, and the path to social justice
Moore, J.
2003-01-01
Traditional psychology is mentalistic in the sense that it appeals to inner causes in the explanation of behavior. Two examples of mentalism in traditional psychology are (a) dispositional attributions and (b) conventional treatments of intelligence. These examples may be linked to such pernicious social -isms as racism and sexism by noting that some individuals justify engaging in discriminatory conduct toward others by appealing to some deficient inner quality of those being discriminated against. This sort of mentalistic appeal ultimately prevents some members of our society from being integrated into society and from progressing down the path of social justice. Behavior analysis offers a constructional alternative to the mentalistic views of traditional psychology and allows our society as a whole to move down the path. PMID:22478401
NASA Astrophysics Data System (ADS)
Murata, Masayuki; Yamamoto, Atsushi; Hasegawa, Yasuhiro; Komine, Takashi; Endo, Akira
2017-01-01
In this study, the electrical resistivity and Seebeck coefficient of bismuth nanowires, several hundred nanometers in diameter, are calculated using the Boltzmann equation in the relaxation time approximation. The three-dimensional density of states and properties of single-crystalline bulk bismuth, such as carrier density, effective mass, and mobility, are used in the calculation without considering the quantum size effect. The relaxation times of the electrons and holes are calculated using Matthiessen's rule considering the carrier collisions at the wire boundary. The temperature, crystal orientation, and diameter dependence of the electrical resistivity and Seebeck coefficient are investigated. The calculation demonstrates that the electrical resistivity increases gradually with decreasing wire diameter, and the temperature coefficient of the electrical resistivity varies from positive to negative at low temperatures for thin wires with diameters less than approximately 500 nm. The diameter dependence of the electrical resistivity varies with the crystal orientation; the increase along the bisectrix axis is larger than that along the binary and trigonal axes. The temperature dependence of the Seebeck coefficient also strongly depends on the crystal orientation. The absolute value of the negative Seebeck coefficient along the bisectrix axis rapidly decreases with decreasing diameter and even changes sign from negative to positive at low temperatures despite the charge neutrality condition, while the Seebeck coefficients along the binary and trigonal axes do not differ significantly from those of single-crystalline bulk bismuth. We conclude that the thermoelectric properties of bismuth nanowires strongly depend not only on the wire diameter but also on the crystal orientation.
NASA Astrophysics Data System (ADS)
Yan, Yangqian; Blume, D.
2016-05-01
The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astro physics. This work determines the fourth-order virial coefficient b4 of such a strongly-interacting Fermi gas using a customized ab inito path integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4, our b4 agrees with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly anti-symmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions. We gratefully acknowledge support by the NSF.
NASA Astrophysics Data System (ADS)
Yan, Yangqian; Blume, D.
2016-06-01
The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b4 of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4 , our b4 agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.
Zarabadi, Atefeh S; Pawliszyn, Janusz
2015-02-17
Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain.
Path-sensitive analysis for reducing rollback overheads
O'Brien, John K.P.; Wang, Kai-Ting Amy; Yamashita, Mark; Zhuang, Xiaotong
2014-07-22
A mechanism is provided for path-sensitive analysis for reducing rollback overheads. The mechanism receives, in a compiler, program code to be compiled to form compiled code. The mechanism divides the code into basic blocks. The mechanism then determines a restore register set for each of the one or more basic blocks to form one or more restore register sets. The mechanism then stores the one or more register sets such that responsive to a rollback during execution of the compiled code. A rollback routine identifies a restore register set from the one or more restore register sets and restores registers identified in the identified restore register set.
Analysis of the contact graph routing algorithm: Bounding interplanetary paths
NASA Astrophysics Data System (ADS)
Birrane, Edward; Burleigh, Scott; Kasch, Niels
2012-06-01
Interplanetary communication networks comprise orbiters, deep-space relays, and stations on planetary surfaces. These networks must overcome node mobility, constrained resources, and significant propagation delays. Opportunities for wireless contact rely on calculating transmit and receive opportunities, but the Euclidean-distance diameter of these networks (measured in light-seconds and light-minutes) precludes node discovery and contact negotiation. Propagation delay may be larger than the line-of-sight contact between nodes. For example, Mars and Earth orbiters may be separated by up to 20.8 min of signal propagation time. Such spacecraft may never share line-of-sight, but may uni-directionally communicate if one orbiter knows the other's future position. The Contact Graph Routing (CGR) approach is a family of algorithms presented to solve the messaging problem of interplanetary communications. These algorithms exploit networks where nodes exhibit deterministic mobility. For CGR, mobility and bandwidth information is pre-configured throughout the network allowing nodes to construct transmit opportunities. Once constructed, routing algorithms operate on this contact graph to build an efficient path through the network. The interpretation of the contact graph, and the construction of a bounded approximate path, is critically important for adoption in operational systems. Brute force approaches, while effective in small networks, are computationally expensive and will not scale. Methods of inferring cycles or other librations within the graph are difficult to detect and will guide the practical implementation of any routing algorithm. This paper presents a mathematical analysis of a multi-destination contact graph algorithm (MD-CGR), demonstrates that it is NP-complete, and proposes realistic constraints that make the problem solvable in polynomial time, as is the case with the originally proposed CGR algorithm. An analysis of path construction to complement hop
On the use of beta coefficients in meta-analysis.
Peterson, Robert A; Brown, Steven P
2005-01-01
This research reports an investigation of the use of standardized regression (beta) coefficients in meta-analyses that use correlation coefficients as the effect-size metric. The investigation consisted of analyzing more than 1,700 corresponding beta coefficients and correlation coefficients harvested from published studies. Results indicate that, under certain conditions, using knowledge of corresponding beta coefficients to input missing correlations (effect sizes) generally produces relatively accurate and precise population effect-size estimates. Potential benefits from applying this knowledge include smaller sampling errors because of increased numbers of effect sizes and smaller non-sampling errors because of the inclusion of a broader array of research designs.
Path analysis of agro-industrial traits in sweet sorghum.
Lombardi, G M R; Nunes, J A R; Parrella, R A C; Teixeira, D H L; Bruzi, A T; Durães, N N L; Fagundes, T G
2015-12-09
Sweet sorghum has considerable potential for ethanol production due to its succulent stalks that contain directly fermentable sugars. Since many traits need to be considered in the selection process to breed superior cultivars for ethanol production, then correlations between the traits might be of use to help the breeder define optimal improvement strategies. The aim of this study was to investigate the association between the principal agro-industrial traits in sweet sorghum, and to evaluate the direct and indirect effects of primary and secondary traits on ethanol production per hectare. In total, 45 sweet sorghum genotypes (lineage/hybrids) were evaluated in an experiment designed in an alpha lattice 5 x 9. The data were analyzed using a mixed model approach. A detailed study of simple correlations was accomplished using path analysis. The experimental precision was high, with an accuracy above 76%. The various genotypes showed genetic variation for all agronomic and industrial traits, except stalk diameter. Some agro-industrial traits showed significant simple correlations with ethanol production, but according to the path analysis, some of these traits did not show a significant direct or indirect effect on ethanol production. The results highlighted the primary and secondary traits with practical relevance to sweet sorghum breeding, since they showed director indirect effects on ethanol production.
NASA Astrophysics Data System (ADS)
Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel
2016-04-01
Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (klN) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show klN for benzene varied from 0.022 to 0.60 d- 1. Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties.
Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel
2016-04-01
Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (kl(N)) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show kl(N) for benzene varied from 0.022 to 0.60d(-1). Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties. Copyright © 2016 Elsevier B.V. All rights reserved.
Path Analysis of Household Energy Use - Neighborhood Comparison
NASA Astrophysics Data System (ADS)
Tenjin, Nanako
Many have studied residential energy use in relation with appliance types and efficiency, dwelling types, behavior, socio-demographics, and geography. Yet little is understood about the interrelations among the variables in the context of energy use. We used data collected through residential energy surveys from two neighborhoods in California. Path analysis models with emphasis on the appliance characteristics, appliance usage, and household energy use were developed and statistically tested. Our study showed that even a simple demographic variable like household size has unique effect channels on household energy use and also the channel was significant in one neighborhood but not in the other. While our model leaves much to be improved, the model supports a framework of energy use to explain energy use from a behavioral perspective in which household decisions were related to socio-demographic characteristics but neighborhood difference also plays a major role.
Path analysis of self-efficacy and diving performance revisited.
Feltz, Deborah L; Chow, Graig M; Hepler, Teri J
2008-06-01
The Feltz (1982) path analysis of the relationship between diving efficacy and performance showed that, over trials, past performance was a stronger predictor than self-efficacy of performance. Bandura (1997) criticized the study as statistically "overcontrolling" for past performance by using raw past performance scores along with self-efficacy as predictors of performance. He suggests residualizing past performance by regressing the raw scores on self-efficacy and entering them into the model to remove prior contributions of self-efficacy imbedded in past performance scores. To resolve this controversy, we reanalyzed the Feltz data using three statistical models: raw past performance, residual past performance, and a method that residualizes past performance and self-efficacy. Results revealed that self-efficacy was a stronger predictor of performance in both residualized models than in the raw past performance model. Furthermore, the influence of past performance on future performance was weaker when the residualized methods were conducted.
Application of critical path analysis in clinical trials
Kumar, Amal; Chakraborty, Bhaswat S.
2016-01-01
Clinical research operates in a strictly regulated environment under various management models, but a distinct management model of clinical trial (CT) still needs exploration and research. Critical path analysis (CPA) is a management approach can be used for monitoring, analysis, and prediction of success of its time-bound operational activities. A model CT was compiled with 78 activities, which were further merged into 35 major activities. After performing dependence analysis, the list was finalized with 25 activities which were taken in activity predecessor to create a network diagram and perform CPA considering patients, conduct, and outcome. Activities were inclusive, described the trial entirely with accuracy, and were in chronological and logical sequences. This approach does not replace an understanding of or adherence to the requirements contained in all applicable regulations, guidelines or standard operating procedures governing clinical studies but ensures the proper use of operational and decisional approaches including optimal resource management. As the need to meet deadlines becomes more important and the need to produce good, stable project plans, CPA is very useful for determining activities that can lead to project delay. With this approach, project may be effectively monitored, and realistic schedules can be maintained. PMID:26955606
Dropouts from nursing education: path analysis of a national sample.
Munro, B H
1980-01-01
Path analysis was used to test a theoretical model of college nursing student dropouts. Multiple regression was used to assess the relative importance of the predictor variables. Students' self-reported reasons for dropping out were studied by contingency and correlational analyses to determine the relationship between these reasons and individual difference variables. Factor analysis was used to develop scales to measure the variables of locus of control, self-esteem, social integration, and institutional commitment. The sample of students was drawn from the National Longitudinal Study of the High School Class of 1972. Included in the sample were students entering two- and four-year nursing programs full-time in the fall of 1972. These two groups of students were found to be significantly different in measures of cognitive ability and in aspirations for further education. Approximately 27 percent of the two-year and 41 percent of the four-year students withdrew from their nursing programs during this study. Reasons for withdrawal most frequently cited by both groups related to losing interest in nursing and becoming interested in other fields of study. Educational aspirations had the strongest direct effect on persistence in nursing for two-year students; for four-year students, academic ability was the most powerful predictor of persistence.
NASA Astrophysics Data System (ADS)
Pizzini, Edward L.; Shepardson, Daniel P.
The classroom dynamics (class setting, lesson structure, student interactions, and student behaviors) of a traditional laboratory and a problem-solving Search, Solve, Create, and Share (SSCS) model of instruction were compared using path analysis. Class setting was based on small-group/large-group settings. Lesson structure variables were problem finding/refining, research designing, data collecting, data analyzing, and evaluating. The student-student interactions variable was determined by student-student responding, student-student initiating, and student (self-) interaction; while the teacher-student interaction variable was based on teacher-student initiating and teacher-student responding. The dependent variables of student behavior consisted of attending, responding, following, soliciting, and giving. A causal model was hypothesized for both instructional models based on the independent and dependent variables. The hypothesized causal model was tested using path-analysis procedures described by Pedhazur (1982). The hypothesized causal models were adjusted based on path coefficients with levels of significance greater than p = 0.05. While the descriptive data indicated a similarity in the classroom dynamics of the two instructional models, path analysis indicated a difference in the classroom dynamics. In the traditional laboratory model, student behaviors did not correlate to lesson structure, class setting, or student interactions, whereas in the SSCS problem-solving model student behaviors correlated to aspects of the lesson structure, class setting, and student interactions.
Application of Multiple Handle Gas Path Analysis on a Twill Spool Turbofan Engine
2003-02-01
parameters produce deviations in parameters such as pressures, temperatures, fuel flow and rotational speed throughout the engine, these can be...the independent parameters (gas path component characteristics) deltas. Inverting the ICM, a new matrix the Fault Coefficient Matrix ( FCM ) is obtained...a change in the independent parameter using the inverse matrix of J, which is referred to as "Fault Coefficient Matrix" ( FCM ). The J matrix is
Biabani, A R; Pakniyat, H
2008-04-15
Fifteen sesame genotypes were grown in a randomized complete block design with 3 replications during 2004, in experimental station of Agricultural College, Shiraz University in Badjgah, Iran. Many plant traits were scored in the field. Path coefficient analysis and factor analysis divided the 15 measured variables into 5 factors. The 5 factors explained 81% of the total genetic variation in the dependence structure. Factor 1 was strongly associated with number of capsules in the main stem, length of floral axis, number of capsules per plant and plant height. Other factors (2, 3, 4 and 5) explained the rest of genetic variations and may not be important in sesame breeding programs.
Progressive collapse analysis using updated models for alternate path analysis after a blast
NASA Astrophysics Data System (ADS)
Eskew, Edward; Jang, Shinae; Bertolaccini, Kelly
2016-04-01
Progressive collapse is of rising importance within the structural engineering community due to several recent cases. The alternate path method is a design technique to determine the ability of a structure to sustain the loss of a critical element, or elements, and still resist progressive collapse. However, the alternate path method only considers the removal of the critical elements. In the event of a blast, significant damage may occur to nearby members not included in the alternate path design scenarios. To achieve an accurate assessment of the current condition of the structure after a blast or other extreme event, it may be necessary to reduce the strength or remove additional elements beyond the critical members designated in the alternate path design method. In this paper, a rapid model updating technique utilizing vibration measurements is used to update the structural model to represent the real-time condition of the structure after a blast occurs. Based upon the updated model, damaged elements will either have their strength reduced, or will be removed from the simulation. The alternate path analysis will then be performed, but only utilizing the updated structural model instead of numerous scenarios. After the analysis, the simulated response from the analysis will be compared to failure conditions to determine the buildings post-event condition. This method has the ability to incorporate damage to noncritical members into the analysis. This paper will utilize numerical simulations based upon a unified facilities criteria (UFC) example structure subjected to an equivalent blast to validate the methodology.
Qiu, Li; Leng, Shuguang; Wang, Zhongxu; Dai, Yufei; Zheng, Yuxin; Wang, Zengzhen
2007-06-01
Many host factors or biomarkers are involved in the process of early DNA damage induced by occupational exposure to polycyclic aromatic hydrocarbons (PAH) as seen in coke-oven workers. This paper aimed to identify complicated causal interrelationship of various biomarkers using the path analysis. In this analysis, we included 235 subjects (166 coke-oven workers and 69 nonexposed controls) whose data on the comet assay (e.g., Olive tail moment) and cytogenetic analysis of peripheral blood lymphocytes as well as urinary 1-hydroxypyrene (1-OHP) were available. The path analysis showed that coke-oven exposure and tobacco smoke were both significant predictors of the concentrations of urinary 1-OHP (P < 0.05), with a coefficient of determination of 0.75. The factors having significant influence on the Olive tail moment were in the following order: urinary 1-OHP > XRCC1-exon 9 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.22. The variables of relative importance in influencing on cytokinesis-block micronucleus frequencies were in the following order: coke-oven exposure > urinary 1-OHP > age > mEH3 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.27. These results indicated that exogenous agents, especially the coke-oven exposure, played a more important role than the genotypes in the induction of early genetic damage. In conclusion, the path analysis seemed to be an alternative statistical approach for the ascertainment of complicated association among related biomarkers for the assessment of occupational exposure.
Removable partial dentures with rotational paths of insertion: problem analysis.
Firtell, D N; Jacobson, T E
1983-07-01
Removable partial dentures designed to use a rotational path of insertion are technique sensitive. When indicated and when the principles discussed are followed, a denture that uses a rotational path can be highly successful. Tooth coverage can be decreased, which is an advantage in plaque control, caries reduction, and periodontal support. Esthetics can be improved without resorting to intracoronal retainers, and the number of components subject to distortion is reduced. When properly designed and constructed, use of a rotational path of insertion can result in a removable partial denture that is strong, hygienic, and esthetic.
Bai, Shirong; Davis, Michael J; Skodje, Rex T
2015-11-12
The sensitivity of kinetic observables is analyzed using a newly developed sum over histories representation of chemical kinetics. In the sum over histories representation, the concentrations of the chemical species are decomposed into the sum of probabilities for chemical pathways that follow molecules from reactants to products or intermediates. Unlike static flux methods for reaction path analysis, the sum over histories approach includes the explicit time dependence of the pathway probabilities. Using the sum over histories representation, the sensitivity of an observable with respect to a kinetic parameter such as a rate coefficient is then analyzed in terms of how that parameter affects the chemical pathway probabilities. The method is illustrated for species concentration target functions in H2 combustion where the rate coefficients are allowed to vary over their associated uncertainty ranges. It is found that large sensitivities are often associated with rate limiting steps along important chemical pathways or by reactions that control the branching of reactive flux.
Bai, Shirong; Davis, Michael J.; Skodje, Rex T.
2015-11-12
The sensitivity of kinetic observables is analyzed using a newly developed sum over histories representation of chemical kinetics. In the sum over histories representation, the concentrations of the chemical species are decomposed into the sum of probabilities for chemical pathways that follow molecules from reactants to products or intermediates. Unlike static flux methods for reaction path analysis, the sum over histories approach includes the explicit time dependence of the pathway probabilities. Using the sum over histories representation, the sensitivity of an observable with respect to a kinetic parameter such as a rate coefficient is then analyzed in terms of how that parameter affects the chemical pathway probabilities. The method is illustrated for species concentration target functions in H-2 combustion where the rate coefficients are allowed to vary over their associated uncertainty ranges. It is found that large sensitivities are often associated with rate limiting steps along important chemical pathways or by reactions that control the branching of reactive flux
Ghosal, Dipak; Mueller, Stephen Ng
2005-04-01
With multipath routing in mobile ad hoc networks (MANETs), a source can establish multiple routes to a destination for routing data. In MANETs, mulitpath routing can be used to provide route resilience, smaller end-to-end delay, and better load balancing. However, when the multiple paths are close together, transmissions of different paths may interfere with each other, causing degradation in performance. Besides interference, the physical diversity of paths also improves fault tolerance. We present a purely distributed multipath protocol based on the AODV-Multipath (AODVM) protocol called AODVM with Path Diversity (AODVM/PD) that finds multiple paths with a desired degree of correlation between paths specified as an input parameter to the algorithm. We demonstrate through detailed simulation analysis that multiple paths with low degree of correlation determined by AODVM/PD provides both smaller end-to-end delay than AODVM in networks with low mobility and better route resilience in the presence of correlated node failures.
Transition path theory analysis of c-Src kinase activation
Meng, Yilin; Shukla, Diwakar; Pande, Vijay S.; Roux, Benoît
2016-01-01
Nonreceptor tyrosine kinases of the Src family are large multidomain allosteric proteins that are crucial to cellular signaling pathways. In a previous study, we generated a Markov state model (MSM) to simulate the activation of c-Src catalytic domain, used as a prototypical tyrosine kinase. The long-time kinetics of transition predicted by the MSM was in agreement with experimental observations. In the present study, we apply the framework of transition path theory (TPT) to the previously constructed MSM to characterize the main features of the activation pathway. The analysis indicates that the activating transition, in which the activation loop first opens up followed by an inward rotation of the αC-helix, takes place via a dense set of intermediate microstates distributed within a fairly broad “transition tube” in a multidimensional conformational subspace connecting the two end-point conformations. Multiple microstates with negligible equilibrium probabilities carry a large transition flux associated with the activating transition, which explains why extensive conformational sampling is necessary to accurately determine the kinetics of activation. Our results suggest that the combination of MSM with TPT provides an effective framework to represent conformational transitions in complex biomolecular systems. PMID:27482115
Social comparison processes and catastrophising in fibromyalgia: A path analysis.
Cabrera-Perona, V; Buunk, A P; Terol-Cantero, M C; Quiles-Marcos, Y; Martín-Aragón, M
2017-06-01
In addition to coping strategies, social comparison may play a role in illness adjustment. However, little is known about the role of contrast and identification in social comparison in adaptation to fibromyalgia. To evaluate through a path analysis in a sample of fibromyalgia patients, the association between identification and contrast in social comparison, catastrophising and specific health outcomes (fibromyalgia illness impact and psychological distress). 131 Spanish fibromyalgia outpatients (mean age: 50.15, SD = 11.1) filled out a questionnaire. We present a model that explained 33% of the variance in catastrophising by direct effects of more use of upward contrast and downward identification. In addition, 35% of fibromyalgia illness impact variance was explained by less upward identification, more upward contrast and more catastrophising and 42% of the variance in psychological distress by a direct effect of more use of upward contrast together with higher fibromyalgia illness impact. We suggest that intervention programmes with chronic pain and fibromyalgia patients should focus on enhancing the use of upward identification in social comparison, and on minimising the use of upward contrast and downward identification in social comparison.
Texture coefficient analysis of ion beam irradiated copper nanowires
NASA Astrophysics Data System (ADS)
Rana, Pallavi; Chaudhary, Ritika; Chauhan, R. P.
2016-05-01
Radiation may deteriorate physical properties of the materials and leave negative as well as positive impacts especially on crystalline materials. The energy deposited by ions to the grains and grain boundaries could also influence other properties of grains like: strain, reflection of charge carriers from grain boundaries, in addition to their grain size and orientation. The intensity of a peak in the XRD spectra is the direct reflection of orientation of a miller plane in the crystal. The increased intensity symbolizes the crystalline behavior due to defects annealing, while decreased intensity portray the defects formation and slender amorphisation. Orientation distribution function is a probability distribution function that quantified the texture of a polycrystalline material. The coefficients of harmonic expansion of orientation distribution function is the measurement of the texture coefficient `TC'. This study focused on the investigation of effect of ion beam irradiation on the preffered orientation of the planes of copper nanowires.
Texture coefficient analysis of ion beam irradiated copper nanowires
Rana, Pallavi Chaudhary, Ritika Chauhan, R. P.
2016-05-23
Radiation may deteriorate physical properties of the materials and leave negative as well as positive impacts especially on crystalline materials. The energy deposited by ions to the grains and grain boundaries could also influence other properties of grains like: strain, reflection of charge carriers from grain boundaries, in addition to their grain size and orientation. The intensity of a peak in the XRD spectra is the direct reflection of orientation of a miller plane in the crystal. The increased intensity symbolizes the crystalline behavior due to defects annealing, while decreased intensity portray the defects formation and slender amorphisation. Orientation distribution function is a probability distribution function that quantified the texture of a polycrystalline material. The coefficients of harmonic expansion of orientation distribution function is the measurement of the texture coefficient ‘TC’. This study focused on the investigation of effect of ion beam irradiation on the preffered orientation of the planes of copper nanowires.
Kuu, Wei Y; Nail, Steven L; Hardwick, Lisa M
2007-01-01
The spatial distribution of local shelf heat transfer coefficients, Ks, was determined by mapping the transient temperature response of the shelf surface along the serpentine internal channels of the shelf while the temperature of the heat transfer fluid was ramped from -40 degrees to 40 degrees C. The solution of a first-order non-steady-state differential equation resulted in a predicted shelf surface temperature as a function of the shelf fluid temperature at any point along the flow path. During the study, the shelf surfaces were maintained under a thermally insulated condition so that the heat transfers by gas conduction and radiation were negligible. To minimize heat conduction by gas, the chamber was evacuated to a low pressure, such as 100 mTorr. To minimize heat transfers between shelves, shelves were moved close together, with a gap of approximately 3 mm between any two shelves, because the shelf surface temperatures at corresponding vertical locations of two shelves are virtually equal. In addition, this also provides a shielding from radiation heat transfer from shelf to walls. Local heat transfer coefficients at the probed locations h(x) ( approximately Ks) were calculated by fitting the experimental shelf temperature response to the theoretical value. While the resulting values of K(s) are in general agreement with previously reported values, the values of Ks close to the inlet are significantly higher than those of other locations of the shelf channel. This observation is most likely attributed to the variation of the flow pattern of heat transfer fluid within the channels.
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%.
Analysis of biased PET images caused by inaccurate attenuation coefficients.
Son, Young-Don; Kim, Hang-Keun; Kim, Sung-Tae; Kim, Nam-Beom; Kim, Young-Bo; Cho, Zang-Hee
2010-05-01
PET scanners with an elongated axial field of view intended to increase overall system sensitivity, such as the high-resolution research tomograph (HRRT) scanner, have been reported to produce images with decreased signals in the brain stem and cerebellum. The cause of this negative bias of the images was analyzed, and the effects of an inaccurate linear attenuation coefficient (mu-value) of tissue and bones were separately examined. A new phantom was manufactured, and 18 human subjects were recruited for the study. (18)F-FDG PET images were reconstructed using attenuation coefficient maps generated by various algorithms. The algorithms included maximum a posteriori reconstruction for transmission data (MAP-TR) with default priors, MAP-TR with adjusted priors for bone (MAP-TR(adj-b)), MAP-TR with adjusted priors for tissue (MAP-TR(adj-t)), and noise-equivalent count TR and CT-TR. With the CT-TR and MAP-TR(adj-t) algorithms, increased intensity in the brain stem and cerebellum was seen, and negative bias was reduced. With the MAP-TR(adj-t) algorithm, however, positive bias increased in the central region. Inappropriate attenuation coefficients of brain tissue increased the positive or negative bias of reconstructed images, especially for the central regions of the volume. Poor representation of the skull or bone also locally increased the bias in the near regions where bone detection had failed. An inaccurate mu-map obtained from the MAP-TR algorithm caused the bias problem for the HRRT system. The CT-TR algorithm provided a relatively more reliable mu-map that demonstrated a small degree of intensity bias. Appropriate priors for mu-values of each tissue compartment and better classification to distinguish bone from tissue are necessary for accurate attenuation correction.
Prediction of Postoperative Pain using Path Analysis in Older Patients
Kinjo, Sakura; Sands, Laura P.; Lim, Eunjung; Paul, Sudeshna; Leung, Jacqueline M.
2013-01-01
Purpose Effective postoperative pain management is important for older surgical patients since pain affects perioperative outcomes. A prospective cohort study was conducted to describe the direct and indirect effects of patient risk factors and pain treatment in explaining levels of postoperative pain in older surgical patients. Methods We studied patients who were 65 years of age or older and were scheduled for major non-cardiac surgery with a postoperative hospital stay of at least 2 days. The numeric rating scale (0 = no pain, 10 = worst possible pain) was used to measure pain levels before surgery and once daily for 2 days after surgery. Path analysis was performed to examine the association between predictive variables and postoperative pain levels. Results Three hundred fifty patients were studied. The results reveal that preoperative pain level, use of preoperative opioids, female gender, higher ASA physical status, and postoperative pain control methods were the strongest predictors of postoperative pain as measured the first day after surgery. Younger age, greater preoperative symptoms of depression and lower cognitive function also contributed to higher postoperative pain levels. Pain levels on the second day after surgery were strongly predicted by preoperative pain level, use of preoperative opioids, surgical risk, and pain and opioid dose on postoperative day 1. However, younger age, female gender, higher ASA physical status, greater preoperative symptoms of depression, lower cognitive function and postoperative pain control methods indirectly contributed to pain levels on the second day after surgery. Conclusion Although preoperative pain and use of preoperative opioids have the strongest effects on postoperative pain, clinicians should be aware that other factors such as age, gender, surgical risk, preoperative cognitive impairment and depression also contribute to reported postoperative pain. Based on significant statistical correlations, these
NASA Astrophysics Data System (ADS)
Gayvoronskiy, S. A.; Ezangina, T.; Khozhaev, I.
2017-09-01
Considered paper is dedicated to interval control system quality analysis with the help of root locus method and method of coefficient estimates. On the base of the first method, an algorithm of determining examinable vertices of interval characteristic polynomial coefficients polytope, which images determine robust root quality indices. On the base of coefficients method, sufficient conditions, linking coefficients of interval characteristic polynomial coefficients with quantitative estimates of robust root quality indices. With the help of both developed approaches, a robust control quality of unmanned underwater vehicle control systems was analyzed.
Ste-Marie, Diane M; Carter, Michael J; Law, Barbi; Vertes, Kelly; Smith, Victoria
2016-09-01
Research has shown learning advantages for self-controlled practice contexts relative to yoked (i.e., experimenter-imposed) contexts; yet, explanations for this phenomenon remain relatively untested. We examined, via path analysis, whether self-efficacy and intrinsic motivation are important constructs for explaining self-controlled learning benefits. The path model was created using theory-based and empirically supported relationships to examine causal links between these psychological constructs and physical performance. We hypothesised that self-efficacy and intrinsic motivation would have greater predictive power for learning under self-controlled compared to yoked conditions. Participants learned double-mini trampoline progressions, and measures of physical performance, self-efficacy and intrinsic motivation were collected over two practice days and a delayed retention day. The self-controlled group (M = 2.04, SD = .98) completed significantly more skill progressions in retention than their yoked counterparts (M = 1.3, SD = .65). The path model displayed adequate fit, and similar significant path coefficients were found for both groups wherein each variable was predominantly predicted by its preceding time point (e.g., self-efficacy time 1 predicts self-efficacy time 2). Interestingly, the model was not moderated by group; thus, failing to support the hypothesis that self-efficacy and intrinsic motivation have greater predictive power for learning under self-controlled relative to yoked conditions.
ERIC Educational Resources Information Center
Thompson, Bruce
A general linear model (GLM) framework is used to suggest that structure coefficients ought to be interpreted in structural equation modeling confirmatory factor analysis (CFA) studies in which factors are correlated. The computation of structure coefficients in explanatory factor analysis and CFA is explained. Two heuristic data sets are used to…
Comparative Analysis of English Language Student's School Paths at a Mexico University
ERIC Educational Resources Information Center
Robelo, Octaviano García; Marquez, Jorge Hernández; Pérez, Ileana Casasola
2017-01-01
Seven factors related to academic paths of students of the Bachelor of English Language of a public university in Mexico are investigated. With a non-experimental descriptive design, a Likert scale was applied to evaluate the college students' perception of these factors. A comparative analysis between three types of school paths was performed. It…
Factors Affecting Counselor Educators' Integration of Educational Technology: A Path Analysis
ERIC Educational Resources Information Center
Kennedy, John F.
2011-01-01
This study used path analysis to explore the effects of individual and institutional-level factors on counselor educators' integration of technology in counselor education. The study fills a gap in the literature by providing a research-based path model describing counselor educators' integration of technology in counselor education. Counselor…
Factors Affecting Counselor Educators' Integration of Educational Technology: A Path Analysis
ERIC Educational Resources Information Center
Kennedy, John F.
2011-01-01
This study used path analysis to explore the effects of individual and institutional-level factors on counselor educators' integration of technology in counselor education. The study fills a gap in the literature by providing a research-based path model describing counselor educators' integration of technology in counselor education. Counselor…
Survey and Analysis of Surface Warfare Officer Career Path Issues
1989-09-01
this specialization alternative are discussed in Swinger [Ref. 2:pp. 98-100]. 1. Hypothesis 1 The null hypothesis states that each specialization...Maior Career Path Change (NPRDC TN 89-5), Navy Personnel Research and Development Center, October 1988. 2. Swinger , A., "Talent at Sea," U. S. Naval
The solubility of (Ba,Sr)SO 4 precipitates: Thermodynamic equilibrium and reaction path analysis
NASA Astrophysics Data System (ADS)
Felmy, Andrew R.; Rai, Dhanpat; Moore, Dean A.
1993-09-01
The solubility of (Ba,Sr)SO 4 precipitates, varying in SrSO 4 mole fraction from 0.05-0.90, was investigated at room temperature with an equilibration period extending to almost three years. The data show that on or before 315 days of equilibration the precipitates reach a reversible equilibrium with the aqueous solution. The reversibility of this equilibrium was verified both by the attainment of steady-state concentrations with time and by heating the samples to perturb the equilibrium and then observing the slow return to the initial equilibrium state. The dissolution of the (Ba,Sr)SO 4 precipitates does not, in general, follow limiting reaction paths as defined by the Lippmann solutus or stoichiometric dissolution curves. In addition, activity coefficient calculations for the BaSO 4 and SrSO 4 components of the solid phase, using either total bulk analysis or near-surface analysis of the component mole fractions, do not satisfy the Gibbs-Duhem equation, demonstrating that a single solid-solution phase does not control both the aqueous Ba and Sr concentrations. Instead, our long-term equilibration data can be explained by the unavoidable formation of small amounts of barite and substitution of Sr into a solid-solution phase with the BaSO 4 component of the solid-solution phase never reaching thermodynamic equilibrium with the aqueous phase.
Path integral analysis of Jarzynski's equality: analytical results.
Minh, David D L; Adib, Artur B
2009-02-01
We apply path integrals to study nonequilibrium work theorems in the context of Brownian dynamics, deriving in particular the equations of motion governing the most typical and most dominant trajectories. For the analytically soluble cases of a moving harmonic potential and a harmonic oscillator with a time-dependent natural frequency, we find such trajectories, evaluate the work-weighted propagators, and validate Jarzynski's equality.
An improved path flux analysis with multi generations method for mechanism reduction
NASA Astrophysics Data System (ADS)
Wang, Wei; Gou, Xiaolong
2016-03-01
An improved path flux analysis with a multi generations (IMPFA) method is proposed to eliminate unimportant species and reactions, and to generate skeletal mechanisms. The production and consumption path fluxes of each species at multiple reaction paths are calculated and analysed to identify the importance of the species and of the elementary reactions. On the basis of the indexes of each reaction path of the first, second, and third generations, the improved path flux analysis with two generations (IMPFA2) and improved path flux analysis with three generations (IMPFA3) are used to generate skeletal mechanisms that contain different numbers of species. The skeletal mechanisms are validated in the case of homogeneous autoignition and perfectly stirred reactor of methane and n-decane/air mixtures. Simulation results of the skeletal mechanisms generated by IMPFA2 and IMPFA3 are compared with those obtained by path flux analysis (PFA) with two and three generations, respectively. The comparisons of ignition delay times, final temperatures, and temperature dependence on flow residence time show that the skeletal mechanisms generated by the present IMPFA method are more accurate than those obtained by the PFA method, with almost the same number of species under a range of initial conditions. By considering the accuracy and computational efficiency, when using the IMPFA (or PFA) method, three generations may be the best choice for the reduction of large-scale detailed chemistry.
Bayesian Meta-Analysis of Cronbach's Coefficient Alpha to Evaluate Informative Hypotheses
ERIC Educational Resources Information Center
Okada, Kensuke
2015-01-01
This paper proposes a new method to evaluate informative hypotheses for meta-analysis of Cronbach's coefficient alpha using a Bayesian approach. The coefficient alpha is one of the most widely used reliability indices. In meta-analyses of reliability, researchers typically form specific informative hypotheses beforehand, such as "alpha of…
Bayesian Meta-Analysis of Cronbach's Coefficient Alpha to Evaluate Informative Hypotheses
ERIC Educational Resources Information Center
Okada, Kensuke
2015-01-01
This paper proposes a new method to evaluate informative hypotheses for meta-analysis of Cronbach's coefficient alpha using a Bayesian approach. The coefficient alpha is one of the most widely used reliability indices. In meta-analyses of reliability, researchers typically form specific informative hypotheses beforehand, such as "alpha of…
Calculation and Analysis of Heat Transfer Coefficients in a Circulating Fluidized Bed Boiler Furnace
NASA Astrophysics Data System (ADS)
Wang, Zhiwei; Yang, Jianhua; Li, Qinghai
A new way for the circulating fluidized bed (CFB) boiler research is proposed by the supervisory information system (SIS) in power plant level. The heat transfer coefficient in CFB boiler furnace is calculated and analyzed by the SIS calculation analysis in a commercial CFB boiler, the way how to calculate the heat transfer coefficient in SIS is introduced, and the heat transfer coefficient is accurately received by calculating a large amount of data from database. The relation about the heat transfer coefficient to unit load, bed temperature, bed velocity, and suspension density is analyzed; the linear relation could be accepted for the commercial CFB design. A new calculating and simple way for the heat transfer coefficient of CFB boiler is proposed for CFB boiler design. Using this research result, the reheat spray water flux larger than the design value in lots of commercial CFB boilers is analyzed; the main reason is the designed heat transfer coefficient smaller than the actual value.
Impact of Maternal Death on Household Economy in Rural China: A Prospective Path Analysis
Ye, Fang; Ao, Deng; Feng, Yao; Wang, Lin; Chen, Jie; Huntington, Dale
2015-01-01
Objectives The present study aimed to explore the inter-relationships among maternal death, household economic status after the event, and potential influencing factors. Methods We conducted a prospective cohort study of households that had experienced maternal death (n = 195) and those that experienced childbirth without maternal death (n = 384) in rural China. All the households were interviewed after the event occurred and were followed up 12 months later. Structural equation modeling was used to test the relationship model, utilizing income and expenditure per capita in the following year after the event as the main outcome variables, maternal death as the predictor, and direct costs, the amount of money offset by positive and negative coping strategies, whether the husband remarried, and whether the newborn was alive as the mediators. Results In the following year after the event, the path analysis revealed a direct effect from maternal death to lower income per capita (standardized coefficient = -0.43, p = 0.041) and to lower expenditure per capita (standardized coefficient = -0.51, p<0.001). A significant indirect effect was found from maternal death to lower income and expenditure per capita mediated by the influencing factors of higher direct costs, less money from positive coping methods, more money from negative coping, and the survival of the newborn. Conclusion This study analyzed the direct and indirect effects of maternal death on a household economy. The results provided evidence for better understanding the mechanism of how this event affects a household economy and provided a reference for social welfare policies to target the most vulnerable households that have suffered from maternal deaths. PMID:26247210
Impact of Maternal Death on Household Economy in Rural China: A Prospective Path Analysis.
Ye, Fang; Ao, Deng; Feng, Yao; Wang, Lin; Chen, Jie; Huntington, Dale; Wang, Haijun; Wang, Yan
2015-01-01
The present study aimed to explore the inter-relationships among maternal death, household economic status after the event, and potential influencing factors. We conducted a prospective cohort study of households that had experienced maternal death (n = 195) and those that experienced childbirth without maternal death (n = 384) in rural China. All the households were interviewed after the event occurred and were followed up 12 months later. Structural equation modeling was used to test the relationship model, utilizing income and expenditure per capita in the following year after the event as the main outcome variables, maternal death as the predictor, and direct costs, the amount of money offset by positive and negative coping strategies, whether the husband remarried, and whether the newborn was alive as the mediators. In the following year after the event, the path analysis revealed a direct effect from maternal death to lower income per capita (standardized coefficient = -0.43, p = 0.041) and to lower expenditure per capita (standardized coefficient = -0.51, p<0.001). A significant indirect effect was found from maternal death to lower income and expenditure per capita mediated by the influencing factors of higher direct costs, less money from positive coping methods, more money from negative coping, and the survival of the newborn. This study analyzed the direct and indirect effects of maternal death on a household economy. The results provided evidence for better understanding the mechanism of how this event affects a household economy and provided a reference for social welfare policies to target the most vulnerable households that have suffered from maternal deaths.
Uncertainty Analysis of Seebeck Coefficient and Electrical Resistivity Characterization
NASA Technical Reports Server (NTRS)
Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred
2014-01-01
In order to provide a complete description of a materials thermoelectric power factor, in addition to the measured nominal value, an uncertainty interval is required. The uncertainty may contain sources of measurement error including systematic bias error and precision error of a statistical nature. The work focuses specifically on the popular ZEM-3 (Ulvac Technologies) measurement system, but the methods apply to any measurement system. The analysis accounts for sources of systematic error including sample preparation tolerance, measurement probe placement, thermocouple cold-finger effect, and measurement parameters; in addition to including uncertainty of a statistical nature. Complete uncertainty analysis of a measurement system allows for more reliable comparison of measurement data between laboratories.
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
Currently, clustering with some form of correlation coefficient as the gene similarity metric has become a popular method for profiling genomic data. The Pearson correlation coefficient and the standard deviation (SD)-weighted correlation coefficient are the two most widely-used correlations as the similarity metrics in clustering microarray data. However, these two correlations are not optimal for analyzing replicated microarray data generated by most laboratories. An effective correlation coefficient is needed to provide statistically sufficient analysis of replicated microarray data. In this study, we describe a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. The value of SCC is revealed by its comparison with two other correlation coefficients that are currently the most widely-used (Pearson correlation coefficient and SD-weighted correlation coefficient) using statistical measures on both synthetic expression data as well as real gene expression data from Saccharomyces cerevisiae. Two leading clustering methods, hierarchical and k-means clustering were applied for the comparison. The comparison indicated that using SCC achieves better clustering performance. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. Functional analysis suggested that some of the genetic mechanisms that control germination in such diverse plant lineages as mosses and angiosperms are also conserved among ferns. This study shows that SCC is an alternative to the Pearson
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
2008-01-01
Background Currently, clustering with some form of correlation coefficient as the gene similarity metric has become a popular method for profiling genomic data. The Pearson correlation coefficient and the standard deviation (SD)-weighted correlation coefficient are the two most widely-used correlations as the similarity metrics in clustering microarray data. However, these two correlations are not optimal for analyzing replicated microarray data generated by most laboratories. An effective correlation coefficient is needed to provide statistically sufficient analysis of replicated microarray data. Results In this study, we describe a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. The value of SCC is revealed by its comparison with two other correlation coefficients that are currently the most widely-used (Pearson correlation coefficient and SD-weighted correlation coefficient) using statistical measures on both synthetic expression data as well as real gene expression data from Saccharomyces cerevisiae. Two leading clustering methods, hierarchical and k-means clustering were applied for the comparison. The comparison indicated that using SCC achieves better clustering performance. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. Functional analysis suggested that some of the genetic mechanisms that control germination in such diverse plant lineages as mosses and angiosperms are also conserved among ferns. Conclusion This study shows that SCC is
Path analysis of the energy density of wood in eucalyptus clones.
Couto, A M; Teodoro, P E; Trugilho, P F
2017-03-16
Path analysis has been used for establishing selection criteria in genetic breeding programs for several crops. However, it has not been used in eucalyptus breeding programs yet. In the present study, we aimed to identify the wood technology traits that could be used as the criteria for direct and indirect selection of eucalyptus genotypes with high energy density of wood. Twenty-four eucalyptus clones were evaluated in a completely randomized design with five replications. The following traits were assessed: basic wood density, total extractives, lignin content, ash content, nitrogen content, carbon content, hydrogen content, sulfur content, oxygen content, higher calorific power, holocellulose, and energy density. After verifying the variability of all evaluated traits among the clones, a two-dimensional correlation network was used to determine the phenotypic patterns among them. The obtained coefficient of determination (0.94) presented a higher magnitude in relation to the effect of the residual variable, and it served as an excellent model for explaining the genetic effects related to the variations observed in the energy density of wood in all eucalyptus clones. However, for future studies, we recommend evaluating other traits, especially the morphological traits, because of the greater ease in their measurement. Selecting clones with high basic density is the most promising strategy for eucalyptus breeding programs that aim to increase the energy density of wood because of its high heritability and magnitude of the cause-and-effect relationship with this trait.
Multidimensional stock network analysis: An Escoufier's RV coefficient approach
NASA Astrophysics Data System (ADS)
Lee, Gan Siew; Djauhari, Maman A.
2013-09-01
The current practice of stocks network analysis is based on the assumption that the time series of closed stock price could represent the behaviour of the each stock. This assumption leads to consider minimal spanning tree (MST) and sub-dominant ultrametric (SDU) as an indispensible tool to filter the economic information contained in the network. Recently, there is an attempt where researchers represent stock not only as a univariate time series of closed price but as a bivariate time series of closed price and volume. In this case, they developed the so-called multidimensional MST to filter the important economic information. However, in this paper, we show that their approach is only applicable for that bivariate time series only. This leads us to introduce a new methodology to construct MST where each stock is represented by a multivariate time series. An example of Malaysian stock exchange will be presented and discussed to illustrate the advantages of the method.
Path Length Entropy Analysis of Diastolic Heart Sounds
Griffel, B.; Zia, M. K.; Fridman, V.; Saponieri, C.; Semmlow, J. L.
2013-01-01
Early detection of coronary artery disease (CAD) using the acoustic approach, a noninvasive and cost-effective method, would greatly improve the outcome of CAD patients. To detect CAD, we analyze diastolic sounds for possible CAD murmurs. We observed diastolic sounds to exhibit 1/f structure and developed a new method, path length entropy (PLE) and a scaled version (SPLE), to characterize this structure to improve CAD detection. We compare SPLE results to Hurst exponent, Sample entropy and Multi-scale entropy for distinguishing between normal and CAD patients. SPLE achieved a sensitivity-specificity of 80%–81%, the best of the tested methods. However, PLE and SPLE are not sufficient to prove nonlinearity, and evaluation using surrogate data suggests that our cardiovascular sound recordings do not contain significant nonlinear properties. PMID:23930808
Abraham, Michael H; Gil-Lostes, Javier; Corr, Stuart; Acree, William E
2012-11-23
Gas-water partition coefficients, K(w), and gas-solvent partition coefficients, K(s), have been determined for chlorodifluoromethane and for 1,1,1,3,3,3-hexafluoropropane by headspace analysis, using a very simple experimental procedure. These partition coefficients then yield water-solvent partition coefficients, P(s). Where comparisons can be made there is excellent agreement with literature values for K(w) and P(s). The obtained values of K(s) and P(s) can be used to obtain physicochemical properties, or descriptors, for the refrigerants. Combination of these descriptors with previous equations we have developed enables partition coefficients to be obtained for a host of systems. Copyright © 2012 Elsevier B.V. All rights reserved.
Pawel, David; Leggett, Richard Wayne; Eckerman, Keith F; Nelson, Christopher
2007-01-01
Federal Guidance Report No. 13 (FGR 13) provides risk coefficients for estimation of the risk of cancer due to low-level exposure to each of more than 800 radionuclides. Uncertainties in risk coefficients were quantified in FGR 13 for 33 cases (exposure to each of 11 radionuclides by each of three exposure pathways) on the basis of sensitivity analyses in which various combinations of plausible biokinetic, dosimetric, and radiation risk models were used to generate alternative risk coefficients. The present report updates the uncertainty analysis in FGR 13 for the cases of inhalation and ingestion of radionuclides and expands the analysis to all radionuclides addressed in that report. The analysis indicates that most risk coefficients for inhalation or ingestion of radionuclides are determined within a factor of 5 or less by current information. That is, application of alternate plausible biokinetic and dosimetric models and radiation risk models (based on the linear, no-threshold hypothesis with an adjustment for the dose and dose rate effectiveness factor) is unlikely to change these coefficients by more than a factor of 5. In this analysis the assessed uncertainty in the radiation risk model was found to be the main determinant of the uncertainty category for most risk coefficients, but conclusions concerning the relative contributions of risk and dose models to the total uncertainty in a risk coefficient may depend strongly on the method of assessing uncertainties in the risk model.
Global Qualitative Flow-Path Modeling for Local State Determination in Simulation and Analysis
NASA Technical Reports Server (NTRS)
Malin, Jane T. (Inventor); Fleming, Land D. (Inventor)
1998-01-01
For qualitative modeling and analysis, a general qualitative abstraction of power transmission variables (flow and effort) for elements of flow paths includes information on resistance, net flow, permissible directions of flow, and qualitative potential is discussed. Each type of component model has flow-related variables and an associated internal flow map, connected into an overall flow network of the system. For storage devices, the implicit power transfer to the environment is represented by "virtual" circuits that include an environmental junction. A heterogeneous aggregation method simplifies the path structure. A method determines global flow-path changes during dynamic simulation and analysis, and identifies corresponding local flow state changes that are effects of global configuration changes. Flow-path determination is triggered by any change in a flow-related device variable in a simulation or analysis. Components (path elements) that may be affected are identified, and flow-related attributes favoring flow in the two possible directions are collected for each of them. Next, flow-related attributes are determined for each affected path element, based on possibly conflicting indications of flow direction. Spurious qualitative ambiguities are minimized by using relative magnitudes and permissible directions of flow, and by favoring flow sources over effort sources when comparing flow tendencies. The results are output to local flow states of affected components.
Factors influencing first childbearing timing decisions among men: Path analysis
Kariman, Nourossadat; Amerian, Maliheh; Jannati, Padideh; Salmani, Fatemeh
2016-01-01
Background: Factors that influence men’s childbearing intentions have been relatively unexplored in the literature. Objective: This study aimed to determine the influencing factors about the first childbearing timing decisions of men. Materials and Methods: In this cross-sectional study, 300 men who were referred to private and governmental healthcare centers in Shahrood, Iran were randomly recruited from April to September 2014. Data were collected using a demographic questionnaire, the Quality of Life Questionnaire; ENRICH Marital Satisfaction Questionnaire, Synder’s Hope Scale, and the Multidimensional Scale of Perceived Social Support. Results: After removing the statistically insignificant paths, men’s age at marriage had the highest direct effect (β=0.86) on their first childbearing decision. Marital satisfaction (β=-0.09), social support (β=0.06), economic status (β=0.06), and quality of life (β=-0.08) were other effective factors on men’s first childbearing decisions. Moreover, marital satisfaction and social support had significant indirect effects on men’s childbearing decisions (β=-0.04 and -0.01, respectively). Conclusion: Many factors, including personal factors (age at marriage and quality of life), family factors (marital satisfaction), and social factors (social support), can affect men’s decision to have a child. Policymakers are hence required to develop strategies to promote the socioeconomic and family conditions of the couples and to encourage them to have as many children as they desire at an appropriate time. PMID:27738661
Physical Analysis of the Drag and Magnus Coefficients of the Topspin Tennis Ball
NASA Astrophysics Data System (ADS)
Smith, Elizabeth; Howald, Craig
2007-05-01
We experimentally determined the drag and Magnus coefficients of a topspin tennis ball using video analysis. Three video cameras were used to record the initial spin, projectile motion, and final spin of the ball. From these recordings the initial velocity, initial spin, final spin, horizontal acceleration, vertical acceleration, x position, and y positions of the ball were extracted. The coefficient of drag was calculated to be CD=0.6104 +/-0.06187 and the Magnus coefficient was calculated to be CM=0.6576+/-0.08767. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.OSS07.P1.14
Exact Analysis of Squared Cross-Validity Coefficient in Predictive Regression Models.
Shieh, Gwowen
2009-01-01
In regression analysis, the notion of population validity is of theoretical interest for describing the usefulness of the underlying regression model, whereas the presumably more important concept of population cross-validity represents the predictive effectiveness for the regression equation in future research. It appears that the inference procedures of the squared multiple correlation coefficient have been extensively developed. In contrast, a full range of statistical methods for the analysis of the squared cross-validity coefficient is considerably far from complete. This article considers a distinct expression for the definition of the squared cross-validity coefficient as the direct connection and monotone transformation to the squared multiple correlation coefficient. Therefore, all the currently available exact methods for interval estimation, power calculation, and sample size determination of the squared multiple correlation coefficient are naturally modified and extended to the analysis of the squared cross-validity coefficient. The adequacies of the existing approximate procedures and the suggested exact method are evaluated through a Monte Carlo study. Furthermore, practical applications in areas of psychology and management are presented to illustrate the essential features of the proposed methodologies. The first empirical example uses 6 control variables related to driver characteristics and traffic congestion and their relation to stress in bus drivers, and the second example relates skills, cognitive performance, and personality to team performance measures. The results in this article can facilitate the recommended practice of cross-validation in psychological and other areas of social science research.
Someswara Rao, Chinta; Viswanadha Raju, S.
2016-01-01
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. PMID:26981409
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.
Sesli, M; Yegenoglu, E D
2010-11-16
Five different similarity coefficients (Jaccard, Sorensen-Dice, simple matching, Rogers and Tanimoto, and Russel and Rao) were evaluated and 10 wild olives analyzed with RAPD markers. The influence of the similarity coefficients on wild olives clustering was investigated. Forty-five primers were used on samples from 10 wild olives (Wild 1 and 2 obtained from Mugla province; Wild 3, 4, 5, 6, 7, and 8 from Manisa province and Wild 9 and 10 from Izmir province of Turkey). The similarity matrices obtained from RAPD markers were compared by the Mantel test. Cluster analysis was made with UPGMA dendrograms, and the consensus fork indexes between all pairs of dendrograms were calculated. The Jaccard and Sorensen-Dice coefficients gave the same results, due to the fact that both exclude negative co-occurrences. The dendrograms using the simple matching and Rogers and Tanimoto coefficients were similar; Wild 4 (Akhisar, Manisa) and Wild 9 (Bornova, Izmir) olives had the closest genetic similarities. This occurred because these coefficients include negative co-occurrences. The Russel and Rao coefficients produced different results, because they include negative co-occurrences in the denominator. We concluded that the coefficients that do not include negative co-occurrences are more efficient for studies of wild olives clustering based on RAPD markers.
ERIC Educational Resources Information Center
Carley, Kathleen M.; And Others
1993-01-01
Discussion of citation networks as a reflection of the intellectual developments in a scientific field focuses on an analysis of citations in the "Journal of Conflict Resolution." Main path analysis is described; the development of the field of conflict resolution is discussed; and interdisciplinarity is explored. (17 references) (LRW)
Effect of perfectly matched layer reflection coefficient on modal analysis of leaky waveguide modes.
Lai, Chih-Hsien; Chang, Hung-chun
2011-01-17
The reflection coefficient is one important parameter of the perfectly matched layer (PML). Here we investigate its effect on the modal analysis of leaky waveguide modes by examining three different leaky waveguide structures, i.e., the holey fiber, the air-core terahertz pipe waveguide, and the gain-guided and index-antiguided slab waveguide. Numerical results reveal that the typical values 10(-8) ~10(-12) are inadequate for obtaining the imaginary part of the complex propagation constant, and the suggested reflection coefficient would be much smaller, for example, 10(-50) or 10(-100). With such a small coefficient, both the computational window size and the PML thickness can be significantly reduced without loss of stability. Moreover, in some cases, the modal field profiles can only be accurately obtained with such a small coefficient.
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 (p<0.0001), I(2)=73%, test for overall effect Z=8.67 (p<0.00001). ADCmin correlated 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.
An Optimization-Driven Analysis Pipeline to Uncover Biomarkers and Signaling Paths: Cervix Cancer
Lorenzo, Enery; Camacho-Caceres, Katia; Ropelewski, Alexander J.; Rosas, Juan; Ortiz-Mojer, Michael; Perez-Marty, Lynn; Irizarry, Juan; Gonzalez, Valerie; Rodríguez, Jesús A.; Cabrera-Rios, Mauricio; Isaza, Clara
2015-01-01
Establishing how a series of potentially important genes might relate to each other is relevant to understand the origin and evolution of illnesses, such as cancer. High-throughput biological experiments have played a critical role in providing information in this regard. A special challenge, however, is that of trying to conciliate information from separate microarray experiments to build a potential genetic signaling path. This work proposes a two-step analysis pipeline, based on optimization, to approach meta-analysis aiming to build a proxy for a genetic signaling path. PMID:26388997
Density-dependent analysis of nonequilibrium paths improves free energy estimates
Minh, David D. L.
2009-01-01
When a system is driven out of equilibrium by a time-dependent protocol that modifies the Hamiltonian, it follows a nonequilibrium path. Samples of these paths can be used in nonequilibrium work theorems to estimate equilibrium quantities such as free energy differences. Here, we consider analyzing paths generated with one protocol using another one. It is posited that analysis protocols which minimize the lag, the difference between the nonequilibrium and the instantaneous equilibrium densities, will reduce the dissipation of reprocessed trajectories and lead to better free energy estimates. Indeed, when minimal lag analysis protocols based on exactly soluble propagators or relative entropies are applied to several test cases, substantial gains in the accuracy and precision of estimated free energy differences are observed. PMID:19485432
Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data
Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes
2009-10-19
Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.
NASA Astrophysics Data System (ADS)
Jones, Reese E.; Mandadapu, Kranthi K.
2012-04-01
We present a rigorous Green-Kubo methodology for calculating transport coefficients based on on-the-fly estimates of: (a) statistical stationarity of the relevant process, and (b) error in the resulting coefficient. The methodology uses time samples efficiently across an ensemble of parallel replicas to yield accurate estimates, which is particularly useful for estimating the thermal conductivity of semi-conductors near their Debye temperatures where the characteristic decay times of the heat flux correlation functions are large. Employing and extending the error analysis of Zwanzig and Ailawadi [Phys. Rev. 182, 280 (1969)], 10.1103/PhysRev.182.280 and Frenkel [in Proceedings of the International School of Physics "Enrico Fermi", Course LXXV (North-Holland Publishing Company, Amsterdam, 1980)] to the integral of correlation, we are able to provide tight theoretical bounds for the error in the estimate of the transport coefficient. To demonstrate the performance of the method, four test cases of increasing computational cost and complexity are presented: the viscosity of Ar and water, and the thermal conductivity of Si and GaN. In addition to producing accurate estimates of the transport coefficients for these materials, this work demonstrates precise agreement of the computed variances in the estimates of the correlation and the transport coefficient with the extended theory based on the assumption that fluctuations follow a Gaussian process. The proposed algorithm in conjunction with the extended theory enables the calculation of transport coefficients with the Green-Kubo method accurately and efficiently.
Thomas, S; Fell, D A
1993-01-01
A computer program (MetaCon) is described for the evaluation of flux control, concentration control and branch-point distribution control coefficients of a metabolic pathway. Requiring only the reaction scheme as input, the program produces algebraic expressions for the control coefficients in terms of elasticity coefficients, metabolite concentrations and pathway fluxes. Any of these variables can be substituted by numeric or simple algebraic expressions; the expressions will then be automatically rearranged in terms of the remaining unknown variables. When all variables have been substituted, numeric values will be obtained for the control coefficients. The program is a computerized implementation of the matrix method for the determination of control coefficients. The features of MetaCon are compared with those of other programs available to workers in Metabolic Control Analysis. Potential benefits of, and methods of using, MetaCon are discussed. The mathematical background and validity of the matrix method rules are discussed, and the algorithm used by MetaCon is described. The matrix method is shown to be a specific case of a previously described general formalism for calculating control coefficients. PMID:8503870
Jones, Reese E; Mandadapu, Kranthi K
2012-04-21
We present a rigorous Green-Kubo methodology for calculating transport coefficients based on on-the-fly estimates of: (a) statistical stationarity of the relevant process, and (b) error in the resulting coefficient. The methodology uses time samples efficiently across an ensemble of parallel replicas to yield accurate estimates, which is particularly useful for estimating the thermal conductivity of semi-conductors near their Debye temperatures where the characteristic decay times of the heat flux correlation functions are large. Employing and extending the error analysis of Zwanzig and Ailawadi [Phys. Rev. 182, 280 (1969)] and Frenkel [in Proceedings of the International School of Physics "Enrico Fermi", Course LXXV (North-Holland Publishing Company, Amsterdam, 1980)] to the integral of correlation, we are able to provide tight theoretical bounds for the error in the estimate of the transport coefficient. To demonstrate the performance of the method, four test cases of increasing computational cost and complexity are presented: the viscosity of Ar and water, and the thermal conductivity of Si and GaN. In addition to producing accurate estimates of the transport coefficients for these materials, this work demonstrates precise agreement of the computed variances in the estimates of the correlation and the transport coefficient with the extended theory based on the assumption that fluctuations follow a Gaussian process. The proposed algorithm in conjunction with the extended theory enables the calculation of transport coefficients with the Green-Kubo method accurately and efficiently.
Moraes, Claudia Leite de; Marques, Emanuele Souza; Reichenheim, Michael Eduardo; Ferreira, Marcela de Freitas; Salles-Costa, Rosana
2016-11-01
To investigate the direct and indirect associations between psychological and physical intimate partner violence and the occurrence of common mental disorders (CMD) and how they relate to the occurrence of household food insecurity (HFI). This was a population-based cross-sectional study. Intimate partner violence was assessed using the Brazilian version of the Revised Conflict Tactics Scale (CTS2) and HFI was assessed using the Brazilian Food Insecurity Scale. The propositional analytical model was based on a review of the literature and was tested using path analysis. Duque de Caxias, Greater Rio de Janeiro, Brazil (April-December 2010). Women (n 849) who had been in a relationship in the 12 months preceding the interview. Both psychological and physical violence were found to be major risk factors of HFI. Psychological violence was associated with HFI indirectly via physical violence and CMD, and directly by an unidentified path. The effects of physical violence seemed to be manifested exclusively through CMD. Most of the variables in the propositional model related to socio-economic position, demographic characteristics, degree of women's social support and partner alcohol misuse were retained in the 'final' model, indicating that these factors contribute significantly to the increased likelihood of HFI. The results reinforce the importance of considering domestic violence and other psychosocial aspects of family life when implementing interventions designed to reduce/eradicate HFI.
Vibrational Analysis of a Shipboard Free Electron Laser Beam Path
2011-12-01
springs. Reducing the sprung mass of the system allows for a lower spring rate and more easily produced real springs. The uneven distribution of mass due...the rate change of the deformation is small enough due to the long period of oscillation to allow operation. 35 Figure 21. Underwater...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited VIBRATIONAL ANALYSIS
NASA Technical Reports Server (NTRS)
Nesbitt, J. A.; Heckel, R. W.
1987-01-01
Interdiffusion in Ni-rich Ni-Cr-Al alloys is investigated experimentally after annealing at 1100 and 1200 C using gamma/gamma, gamma/gamma+beta, gamma/gamma+gamma prime, and gamma/gamma+alpha diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the gamma phase of Ni-Cr-Al alloys. The location and extent of maxima and minima in the concentration profiles of the diffusion couples indicate that both cross-term diffusion coefficients are positive. Measurements are also presented of the ternary interdiffusion coefficients of the gamma phase in the Ni-Cr-Al system. It is shown that the interdiffusion coefficients can be accurately predicted by using a ternary finite-difference interdiffusion model.
NASA Technical Reports Server (NTRS)
Nesbitt, J. A.; Heckel, R. W.
1987-01-01
Interdiffusion in Ni-rich Ni-Cr-Al alloys is investigated experimentally after annealing at 1100 and 1200 C using gamma/gamma, gamma/gamma+beta, gamma/gamma+gamma prime, and gamma/gamma+alpha diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the gamma phase of Ni-Cr-Al alloys. The location and extent of maxima and minima in the concentration profiles of the diffusion couples indicate that both cross-term diffusion coefficients are positive. Measurements are also presented of the ternary interdiffusion coefficients of the gamma phase in the Ni-Cr-Al system. It is shown that the interdiffusion coefficients can be accurately predicted by using a ternary finite-difference interdiffusion model.
Analysis of the ACTS-Vancouver Path Propagation Data
NASA Technical Reports Server (NTRS)
Kharadly, M.; Ross, R.; Dow, B.
1996-01-01
The data described here cover the two-year period from 1 December 1993 to 30 November, 1995. The analysis is done for two sets of valid data: (a) observed or total attenuation data, which includes all atmospheric effects plus the additional attenuation resulting from wet antenna surfaces during rain events, and (b) adjusted attenuation data as in (a) minus estimated values of attenuation due to wetting the antenna surfaces. In both cases, average and worst month cumulative distribution functions (CDF's), fade-duration statistics, and fade-slope statistics for the 20 and 27 GHz beacons are presented.
NASA Astrophysics Data System (ADS)
Kim, B.; Eun, S.; Seo, W.; Park, J.; Ahn, J.; Moon, K.
2013-12-01
Aerosols in the atmosphere can scatter and absorb solar radiation and their spatial/temporal distributions are highly inhomogeneous due to short lifetimes (about a few weeks or less). Through scattering and absorption of solar radiation, aerosols directly affect visibility and climate through the modification of the Earth's energy budget (Charlson et al., 1992; Yan, 2007; Wang, 2012). This study investigates long-term trends and characteristics of aerosol light scattering coefficient at Seoul and Baengnyeongdo, 100 km upstream of Seoul, in Korea. Aerosol scattering coefficients were measured continuously with nephelometers. The analysis period is limited to one year of 2011. For the relationship analysis of extinction coefficients (σext) to visibility and aerosol optical depth, σsp observed at 3 p.m. have been used with help of aerosol absorption coefficients (σap) in order to remove its dependence upon relative humidity (RH), and also those of rainy period have been excluded. As expected, σext estimated are inversely proportional to visibility observation by eye. Aerosol extinction coefficients have been vertically integrated with an assumption of nearly well-mixed within an e-folding height to determine aerosol optical depth (τa), and compared with those retrieved from sunphotometer. The results show a reasonable agreement in spite of an inherent difference of each definition. We expect these findings would help to eventually understand aerosol radiative forcing and its effect on the regional climate change around Korea.
ANALYSIS AND DESIGN OF JUMP COEFFICIENTS IN DISCRETE STOCHASTIC DIFFUSION MODELS*
MEINECKE, LINA; ENGBLOM, STEFAN; HELLANDER, ANDREAS; LÖTSTEDT, PER
2017-01-01
In computational systems biology, the mesoscopic model of reaction-diffusion kinetics is described by a continuous time, discrete space Markov process. To simulate diffusion stochastically, the jump coefficients are obtained by a discretization of the diffusion equation. Using unstructured meshes to represent complicated geometries may lead to negative coefficients when using piecewise linear finite elements. Several methods have been proposed to modify the coefficients to enforce the nonnegativity needed in the stochastic setting. In this paper, we present a method to quantify the error introduced by that change. We interpret the modified discretization matrix as the exact finite element discretization of a perturbed equation. The forward error, the error between the analytical solutions to the original and the perturbed equations, is bounded by the backward error, the error between the diffusion of the two equations. We present a backward analysis algorithm to compute the diffusion coefficient from a given discretization matrix. The analysis suggests a new way of deriving nonnegative jump coefficients that minimizes the backward error. The theory is tested in numerical experiments indicating that the new method is superior and also minimizes the forward error. PMID:28611531
ERIC Educational Resources Information Center
Brown, Steven D.; Lent, Robert W.; Telander, Kyle; Tramayne, Selena
2011-01-01
We performed a meta-analytic path analysis of an abbreviated version of social cognitive career theory's (SCCT) model of work performance (Lent, Brown, & Hackett, 1994). The model we tested included the central cognitive predictors of performance (ability, self-efficacy, performance goals), with the exception of outcome expectations. Results…
Errata to the Werts-Linn Comments on Boyle's "Path Analysis and Ordinal Data."
ERIC Educational Resources Information Center
Werts, Charles E.; Linn, Robert L.
The Werts-Linn procedure for dealing with categorical errors of measurement in "Comments on Boyle's 'Path Analysis and Ordinal Data'" in The American Journal of Sociology, volume 76, number 6, May 1971, is shown to be inappropriate to the problem of ordered categories. (For related document, see TM 002 301.) (DB)
ERIC Educational Resources Information Center
Brown, Steven D.; Lent, Robert W.; Telander, Kyle; Tramayne, Selena
2011-01-01
We performed a meta-analytic path analysis of an abbreviated version of social cognitive career theory's (SCCT) model of work performance (Lent, Brown, & Hackett, 1994). The model we tested included the central cognitive predictors of performance (ability, self-efficacy, performance goals), with the exception of outcome expectations. Results…
ERIC Educational Resources Information Center
Hurd, Noelle M.; Stoddard, Sarah A.; Zimmerman, Marc A.
2013-01-01
This study explored how neighborhood characteristics may relate to African American adolescents' internalizing symptoms via adolescents' social support and perceptions of neighborhood cohesion. Participants included 571 urban, African American adolescents (52% female; "M" age = 17.8). A multilevel path analysis testing both direct and…
The Effects of Credibility, Reliance, and Exposure on Media Agenda-Setting: A Path Analysis Model.
ERIC Educational Resources Information Center
Wanta, Wayne; Hu, Yu-Wei
1994-01-01
Uses path analysis to investigate a model of agenda-setting. Supports the model, showing that, if individuals perceive the media to be highly credible, they will rely on the media for information, will increase their exposure to media messages and in turn will become more susceptible to agenda-setting. (SR)
ERIC Educational Resources Information Center
Hurd, Noelle M.; Stoddard, Sarah A.; Zimmerman, Marc A.
2013-01-01
This study explored how neighborhood characteristics may relate to African American adolescents' internalizing symptoms via adolescents' social support and perceptions of neighborhood cohesion. Participants included 571 urban, African American adolescents (52% female; "M" age = 17.8). A multilevel path analysis testing both direct and…
Mathematics Teaching Anxiety and Self-Efficacy Beliefs toward Mathematics Teaching: A Path Analysis
ERIC Educational Resources Information Center
Peker, Murat
2016-01-01
The purpose of this study was to investigate the relationship between pre-service primary school teachers' mathematics teaching anxiety and their self-efficacy beliefs toward mathematics teaching through path analysis. There were a total of 250 pre-service primary school teachers involved in this study. Of the total, 202 were female and 48 were…
Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel.
Toribio, Jesús; González, Beatriz; Matos, Juan-Carlos
2015-11-04
In this paper, a fracto-metallographic analysis was performed on the cracked specimens of cold drawn pearlitic steel subjected to fatigue tests. Fatigue cracks are transcollonial and exhibit a preference for fracturing pearlitic lamellae, with non-uniform crack opening displacement values, micro-discontinuities, branchings, bifurcations and frequent local deflections that create microstructural roughness. At the micro-level, the cold drawn pearlitic steel exhibits higher micro-roughness than the hot rolled bar (this is a consequence of the manufacturing process by cold drawing), so that the actual fractured surface in the cold drawn wire is greater than that in the hot rolled bar, due to the fact that the crack deflection events are more frequent and with higher angle in the former (the heavily drawn prestressing steel wire). These findings show the relevant role on the manufacturing process by cold drawing in the fatigue crack propagation in pearlitic steel.
Evaluation of Reliability Coefficients for Two-Level Models via Latent Variable Analysis
ERIC Educational Resources Information Center
Raykov, Tenko; Penev, Spiridon
2010-01-01
A latent variable analysis procedure for evaluation of reliability coefficients for 2-level models is outlined. The method provides point and interval estimates of group means' reliability, overall reliability of means, and conditional reliability. In addition, the approach can be used to test simple hypotheses about these parameters. The…
Psychometric Inferences from a Meta-Analysis of Reliability and Internal Consistency Coefficients
ERIC Educational Resources Information Center
Botella, Juan; Suero, Manuel; Gambara, Hilda
2010-01-01
A meta-analysis of the reliability of the scores from a specific test, also called reliability generalization, allows the quantitative synthesis of its properties from a set of studies. It is usually assumed that part of the variation in the reliability coefficients is due to some unknown and implicit mechanism that restricts and biases the…
Evaluation of Reliability Coefficients for Two-Level Models via Latent Variable Analysis
ERIC Educational Resources Information Center
Raykov, Tenko; Penev, Spiridon
2010-01-01
A latent variable analysis procedure for evaluation of reliability coefficients for 2-level models is outlined. The method provides point and interval estimates of group means' reliability, overall reliability of means, and conditional reliability. In addition, the approach can be used to test simple hypotheses about these parameters. The…
Analysis and Simulation for a Spotlight-Mode Aircraft SAR in Circular Flight Path
NASA Technical Reports Server (NTRS)
Jin, M.; Chen, M.
1993-01-01
A spotlight aircraft SAR in a circular flight path can efficiently obtain an image with very high azimuth resolution or a wider azimuth viewing angle. An analysis on the spotlight SAR is made regarding the required PRF, the predicted resolution, and the computation complexity as a function of the aircraft altitude and the distance between a target and the center of the flight path projection. An efficient processing algorithm based on the exact wide beam spectrum is presented. The results of simulation indicate that the impulse responses meet the predicted resolution performance.
NASA Astrophysics Data System (ADS)
Hannemann, Klaus; Karl, Sebastian; Martinez Schramm, Jan; Steelant, Johan
2010-10-01
In the framework of the European Commission co-funded LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) project, the methodology of a combined ground-based testing and numerical modelling analysis of supersonic combustion flow paths was established. The approach is based on free jet testing of complete supersonic combustion ramjet (scramjet) configurations consisting of intake, combustor and nozzle in the High Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Center (DLR) and computational fluid dynamics studies utilising the DLR TAU code. The capability of the established methodology is demonstrated by applying it to the flow path of the generic HyShot II scramjet flight experiment configuration.
NASA Astrophysics Data System (ADS)
Ishii, Katsuhiro; Nishidate, Izumi; Iwai, Toshiaki
2014-05-01
Numerical analysis of optical propagation in highly scattering media is investigated when light is normally incident to the surface and re-emerges backward from the same point. This situation corresponds to practical light scattering setups, such as in optical coherence tomography. The simulation uses the path-length-assigned Monte Carlo method based on an ellipsoidal algorithm. The spatial distribution of the scattered light is determined and the dependence of its width and penetration depth on the path-length is found. The backscattered light is classified into three types, in which ballistic, snake, and diffuse photons are dominant.
NASA Astrophysics Data System (ADS)
Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan
2013-09-01
In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.
NASA Astrophysics Data System (ADS)
Jo, Y.; Chang, C.; Koh, H. J.
2014-12-01
The frictional coefficient of fractures, a fundamental parameter needed to analyze a variety of geomechanical problems for microseismicity, is normally determined from laboratory shear tests. However, recovered rock cores are rarely available because of difficulties and high cost in getting undisturbed core samples. In that case, the frictional coefficient should be either assumed or estimated indirectly. We investigate the frictional property of fractures of various sandstones in laboratory tests and attempt to correlate that with other properties measureable relatively readily even without cores. We use various sandstones obtained from different depths of a 1 km deep borehole drilled for coal bed methane development in a Paleozoic sedimentary basin, South Korea. The sandstones have various physical properties (e.g. P-wave velocity (VP) of 2253-5038 m/s) and chemical compositions in terms of clay content (5-31%). We conduct direct shear tests in an artificial saw-cut fracture in the sandstones and determined frictional coefficients in a range of 0.36-0.57. The frictional coefficients have an inverse-linear correlation with clay contents measured from XRD analysis. These results are also quite consistent with those from previous clay gouge experiments (Takahashi et al., 2007; Tembe et al., 2010; Kohli & Zoback, 2013). They also have a linear correlation with VP. Our study demonstrates that frictional coefficients can be estimated empirically from such properties. To check feasibility of such an approach, we apply the obtained empirical relation to the borehole where cores were recovered. The clay contents in sandstone formations are estimated from the borehole gamma ray log calibrated using the XRD clay content data. Clay content estimated from gamma ray varies significantly with depth in a range of 0-45%. This range of clay content corresponds to frictional coefficients of 0.25-0.58. Comparison between estimated and measured frictional coefficients shows a
First order analysis of the effect of pitching on the drag coefficient
Wilson, R.E.; Neff, J.A.
1985-11-01
A first order analysis was made for the drag coefficient of a pitching NACA 0015 airfoil below stall. The inviscid velocity ditribution for a translating NACA 0015 airfoil was superimposed with the additional circulation velocity for a pitching ellipse. The resulting velocity distribution was used to numerically integrate a momentum/boundary layer formulation to obtain the drag coefficient. For both laminar and turbulent boundary layers it was found that the effect of pitching on the drag coefficient can be approximated by a shift in angle of attack. The shift angle was found to be a linear function of the pitching velocity and to be less than the induced angle of attack caused by the pitching.
Vulnerabilities, Influences and Interaction Paths: Failure Data for Integrated System Risk Analysis
NASA Technical Reports Server (NTRS)
Malin, Jane T.; Fleming, Land
2006-01-01
We describe graph-based analysis methods for identifying and analyzing cross-subsystem interaction risks from subsystem connectivity information. By discovering external and remote influences that would be otherwise unexpected, these methods can support better communication among subsystem designers at points of potential conflict and to support design of more dependable and diagnosable systems. These methods identify hazard causes that can impact vulnerable functions or entities if propagated across interaction paths from the hazard source to the vulnerable target. The analysis can also assess combined impacts of And-Or trees of disabling influences. The analysis can use ratings of hazards and vulnerabilities to calculate cumulative measures of the severity and importance. Identification of cross-subsystem hazard-vulnerability pairs and propagation paths across subsystems will increase coverage of hazard and risk analysis and can indicate risk control and protection strategies.
Vulnerabilities, Influences and Interaction Paths: Failure Data for Integrated System Risk Analysis
NASA Technical Reports Server (NTRS)
Malin, Jane T.; Fleming, Land
2006-01-01
We describe graph-based analysis methods for identifying and analyzing cross-subsystem interaction risks from subsystem connectivity information. By discovering external and remote influences that would be otherwise unexpected, these methods can support better communication among subsystem designers at points of potential conflict and to support design of more dependable and diagnosable systems. These methods identify hazard causes that can impact vulnerable functions or entities if propagated across interaction paths from the hazard source to the vulnerable target. The analysis can also assess combined impacts of And-Or trees of disabling influences. The analysis can use ratings of hazards and vulnerabilities to calculate cumulative measures of the severity and importance. Identification of cross-subsystem hazard-vulnerability pairs and propagation paths across subsystems will increase coverage of hazard and risk analysis and can indicate risk control and protection strategies.
Structure coefficients for different initial metallicities for use in stellar analysis
NASA Astrophysics Data System (ADS)
Inlek, Gulay; Budding, Edwin; Demircan, Osman
2017-09-01
Internal structure coefficients for zero age Main Sequence (ZAMS) model stars with different initial metallicities are presented. A series of (Eggleton) stellar models with masses between 1-40 M_{⊙} and metallicities Z=0.0001, Z=0.001, Z=0.004, Z=0.01, Z=0.02, and Z=0.03 were used. We have also calculated the same coefficients for a recommended solar metallicity value Z=0.0134 (Asplund et al. in Annu. Rev. Astron. Astrophys. 47:481, 2009). For each model, values of the internal structure constants k2, k3, k4 and related coefficients have been derived by numerically integrating Radau's equation with the (FORTRAN) program RADAU. The (Eggleton) stellar models used come from the ` EZ-Web' compilation of the Dept. of Astronomy, University of Wisconsin, Madison. The calculations follow the procedure given by Inlek and Budding (Astrophys. Space Sci. 342:365, 2012). These new results were compared with others in the literature. We deduce that the current state of theoretical evaluation of structure coefficients is generally in sufficient agreement with data obtained from apsidal advance rates of selected well-observed eccentric eclipsing binary stars at the present time, given the probable errors of the latter. However, new results coming from more precise and extensive data sets in the wake of the Kepler Mission, or similar future surveys, may call for further theoretical specification or refinement. The derivation of structure coefficients from observations of apsidal motion in close eccentric binary systems requires specification of relevant parameters from light curve analysis. A self-consistent treatment then implies inclusion of the structure coefficients within the fitting function of such analysis.
Chen, Wenhui; Lei, Yalin
2017-02-01
Identifying the impact path on factors of CO2 emissions is crucial for the government to take effective measures to reduce carbon emissions. The most existing research focuses on the total influence of factors on CO2 emissions without differentiating between the direct and indirect influence. Moreover, scholars have addressed the relationships among energy consumption, economic growth, and CO2 emissions rather than estimating all the causal relationships simultaneously. To fill this research gaps and explore overall driving factors' influence mechanism on CO2 emissions, this paper utilizes a path analysis model with latent variables (PA-LV) to estimate the direct and indirect effect of factors on China's energy-related carbon emissions and to investigate the causal relationships among variables. Three key findings emanate from the analysis: (1) The change in the economic growth pattern inhibits the growth rate of CO2 emissions by reducing the energy intensity; (2) adjustment of industrial structure contributes to energy conservation and CO2 emission reduction by raising the proportion of the tertiary industry; and (3) the growth of CO2 emissions impacts energy consumption and energy intensity negatively, which results in a negative impact indirectly on itself. To further control CO2 emissions, the Chinese government should (1) adjust the industrial structure and actively develop its tertiary industry to improve energy efficiency and develop low-carbon economy, (2) optimize population shifts to avoid excessive population growth and reduce energy consumption, and (3) promote urbanization steadily to avoid high energy consumption and low energy efficiency.
Two-condition within-participant statistical mediation analysis: A path-analytic framework.
Montoya, Amanda K; Hayes, Andrew F
2017-03-01
Researchers interested in testing mediation often use designs where participants are measured on a dependent variable Y and a mediator M in both of 2 different circumstances. The dominant approach to assessing mediation in such a design, proposed by Judd, Kenny, and McClelland (2001), relies on a series of hypothesis tests about components of the mediation model and is not based on an estimate of or formal inference about the indirect effect. In this article we recast Judd et al.'s approach in the path-analytic framework that is now commonly used in between-participant mediation analysis. By so doing, it is apparent how to estimate the indirect effect of a within-participant manipulation on some outcome through a mediator as the product of paths of influence. This path-analytic approach eliminates the need for discrete hypothesis tests about components of the model to support a claim of mediation, as Judd et al.'s method requires, because it relies only on an inference about the product of paths-the indirect effect. We generalize methods of inference for the indirect effect widely used in between-participant designs to this within-participant version of mediation analysis, including bootstrap confidence intervals and Monte Carlo confidence intervals. Using this path-analytic approach, we extend the method to models with multiple mediators operating in parallel and serially and discuss the comparison of indirect effects in these more complex models. We offer macros and code for SPSS, SAS, and Mplus that conduct these analyses. (PsycINFO Database Record
Random effects coefficient of determination for mixed and meta-analysis models.
Demidenko, Eugene; Sargent, James; Onega, Tracy
2012-01-01
The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine.
Analysis of the coefficient of variation in shear and tensile bond strength tests.
Romano, Fábio Lourenço; Ambrosano, Gláucia Maria Bovi; Magnani, Maria Beatriz Borges de Araújo; Nouer, Darcy Flávio
2005-09-01
The coefficient of variation is a dispersion measurement that does not depend on the unit scales, thus allowing the comparison of experimental results involving different variables. Its calculation is crucial for the adhesive experiments performed in laboratories because both precision and reliability can be verified. The aim of this study was to evaluate and to suggest a classification of the coefficient variation (CV) for in vitro experiments on shear and tensile strengths. The experiments were performed in laboratory by fifty international and national studies on adhesion materials. Statistical data allowing the estimation of the coefficient of variation was gathered from each scientific article since none of them had such a measurement previously calculated. Excel worksheet was used for organizing the data while the sample normality was tested by using Shapiro Wilk tests (alpha = 0.05) and the Statistical Analysis System software (SAS). A mean value of 6.11 (SD = 1.83) for the coefficient of variation was found by the data analysis and the data had a normal distribution (p>0.05). A range classification was proposed for the coefficient of variation from such data, that is, it should be considered low for a value lesser than 2.44; intermediate for a value between 2.44 and 7.94, high for a value between 7.94 and 9.78, and finally, very high for a value greater than 9.78. Such classification can be used as a guide for experiments on adhesion materials, thus making the planning easier as well as revealing precision and validity concerning the data.
Gibson, LaTosha M; Gopalan, Balaji; Pisupati, Sarma V; Shadle, Lawrence J
2013-10-01
New robust Lagrangian computational fluid dynamic (CFD) models are powerful tools that can be used to study the behavior of a diverse population of coal particle sizes, densities, and mineral compositions in entrained gasifiers. By using this approach, the responses of the particles impacting the wall were characterized over a range of velocities (1 to 8 m/s) and incident angles (90 to 20°). Within CFD models, the kinematic coefficient of restitution is the boundary condition defining the particle wall behavior. Four surfaces were studied to simulate the physical conditions of different entrained-flow gasification particle–surface collision scenarios: 1) a flat metal plate 2) a low viscosity silicon adhesive, 3) a high viscosity silicon adhesive, and 4) adhered particles on a flat metal plate with Young's modulus of elasticity ranging from 0.9 to 190 GPa. Entrained flow and drop experiments were conducted with granular coke particles, polyethylene beads and polystyrene pellets. The particle normal and tangential coefficients of restitution were measured using high speed imaging and particle tracking. The measured coefficients of restitution were observed to have a strong dependence on the rebound angles for most of the data. Suitable algebraic expressions for the normal and the tangential component of the coefficient of restitution were developed based upon ANOVA analysis. These expressions quantify the effect of normalized Young's modulus, particle equancy, and relative velocity on the coefficient of restitution. The coefficient of restitution did not have a strong dependence on the particle velocity over the range considered as long as the velocity was above the critical velocity. However, strong correlations were found between the degree of equancy of the particles and the mean coefficient of restitution such that the coefficient of restitution decreased for smaller particle equancies. It was concluded that the degree of equancy and the normalized Young
NASA Astrophysics Data System (ADS)
Minina, N. A.; Emishkin, V. A.; Ovchinnikov, I. N.
2017-01-01
The development of an experimental method for the determination of stress concentration coefficient by the photometric analysis of surface reflectivity of material near stress concentrator and at a distance from it is considered in the paper. The experiments were performed with the AD-19 aluminum alloy samples under fatigue test conditions realized at a vibrating table with cantilevered sample. Notches 5 mm long and 0.4 mm wide spaced at constant intervals were applied by electrical discharge along one edge of the samples. The reflections of light from the fragments in the vicinity of the stress concentrator and from the opposite edge of the sample were compared with the help of photometric image analyzer. It is shown that such analysis can be used to determine the stress concentration coefficients.
NASA Technical Reports Server (NTRS)
Maday, Yvon; Ronquist, Einar M.
1989-01-01
The numerical analysis of spectral methods when non-constant coefficients appear in the equation, either due to the original statement of the equations or to take into account the deformed geometry, is presented. Particular attention is devoted to the optimality of the discretization even for low values of the discretization parameter. The effect of some overintegration is also addressed, in order to possibly improve the accuracy of the discretization.
2013-01-01
Background The synthesis of information across microarray studies has been performed by combining statistical results of individual studies (as in a mosaic), or by combining data from multiple studies into a large pool to be analyzed as a single data set (as in a melting pot of data). Specific issues relating to data heterogeneity across microarray studies, such as differences within and between labs or differences among experimental conditions, could lead to equivocal results in a melting pot approach. Results We applied statistical theory to determine the specific effect of different means and heteroskedasticity across 19 groups of microarray data on the sign and magnitude of gene-to-gene Pearson correlation coefficients obtained from the pool of 19 groups. We quantified the biases of the pooled coefficients and compared them to the biases of correlations estimated by an effect-size model. Mean differences across the 19 groups were the main factor determining the magnitude and sign of the pooled coefficients, which showed largest values of bias as they approached ±1. Only heteroskedasticity across the pool of 19 groups resulted in less efficient estimations of correlations than did a classical meta-analysis approach of combining correlation coefficients. These results were corroborated by simulation studies involving either mean differences or heteroskedasticity across a pool of N > 2 groups. Conclusions The combination of statistical results is best suited for synthesizing the correlation between expression profiles of a gene pair across several microarray studies. PMID:23822712
Automatic Match between Delimitation Line and Real Terrain Based on Least-Cost Path Analysis
NASA Astrophysics Data System (ADS)
Feng, C. Q.; Jiang, N.; Zhang, X. N.; Ma, J.
2013-11-01
Nowadays, during the international negotiation on separating dispute areas, manual adjusting is lonely applied to the match between delimitation line and real terrain, which not only consumes much time and great labor force, but also cannot ensure high precision. Concerning that, the paper mainly explores automatic match between them and study its general solution based on Least -Cost Path Analysis. First, under the guidelines of delimitation laws, the cost layer is acquired through special disposals of delimitation line and terrain features line. Second, a new delimitation line gets constructed with the help of Least-Cost Path Analysis. Third, the whole automatic match model is built via Module Builder in order to share and reuse it. Finally, the result of automatic match is analyzed from many different aspects, including delimitation laws, two-sided benefits and so on. Consequently, a conclusion is made that the method of automatic match is feasible and effective.
NASA Astrophysics Data System (ADS)
Uchida, Nariya; Grest, Gary S.; Everaers, Ralf
2008-01-01
We combine computer simulations and scaling arguments to develop a unified view of polymer entanglement based on the primitive path analysis of the microscopic topological state. Our results agree with experimentally measured plateau moduli for three different polymer classes over a wide range of reduced polymer densities: (i) semidilute theta solutions of synthetic polymers, (ii) the corresponding dense melts above the glass transition or crystallization temperature, and (iii) solutions of semiflexible (bio)polymers such as F-actin or suspensions of rodlike viruses. Together, these systems cover the entire range from loosely to tightly entangled polymers. In particular, we argue that the primitive path analysis renormalizes a loosely to a tightly entangled system and provide a new explanation of the successful Lin-Noolandi packing conjecture for polymer melts.
Managbanag, J. R.; Witten, Tarynn M.; Bonchev, Danail; Fox, Lindsay A.; Tsuchiya, Mitsuhiro; Kennedy, Brian K.; Kaeberlein, Matt
2008-01-01
Background Identification of genes that modulate longevity is a major focus of aging-related research and an area of intense public interest. In addition to facilitating an improved understanding of the basic mechanisms of aging, such genes represent potential targets for therapeutic intervention in multiple age-associated diseases, including cancer, heart disease, diabetes, and neurodegenerative disorders. To date, however, targeted efforts at identifying longevity-associated genes have been limited by a lack of predictive power, and useful algorithms for candidate gene-identification have also been lacking. Methodology/Principal Findings We have utilized a shortest-path network analysis to identify novel genes that modulate longevity in Saccharomyces cerevisiae. Based on a set of previously reported genes associated with increased life span, we applied a shortest-path network algorithm to a pre-existing protein–protein interaction dataset in order to construct a shortest-path longevity network. To validate this network, the replicative aging potential of 88 single-gene deletion strains corresponding to predicted components of the shortest-path longevity network was determined. Here we report that the single-gene deletion strains identified by our shortest-path longevity analysis are significantly enriched for mutations conferring either increased or decreased replicative life span, relative to a randomly selected set of 564 single-gene deletion strains or to the current data set available for the entire haploid deletion collection. Further, we report the identification of previously unknown longevity genes, several of which function in a conserved longevity pathway believed to mediate life span extension in response to dietary restriction. Conclusions/Significance This work demonstrates that shortest-path network analysis is a useful approach toward identifying genetic determinants of longevity and represents the first application of network analysis of aging
PathGrid: The Transfer of Astronomical Image Algorithms to the Analysis of Medical Microscopy Data
NASA Astrophysics Data System (ADS)
Walton, N. A.; Brenton, J. D.; Caldas, C.; Irwin, M. J.; Akram, A.; Gonzalez-Solares, E.; Lewis, J. R.; MacCullum, P.; Morris, L. J.; Rixon, G. T.
2009-09-01
We describe our pilot `PathGrid' study which applies astronomical image processing and data handling techniques to the challenges involved in analysing Tissue Micro Array (TMA) image data. Image analysis has been applied to the input TMA data using open source solutions developed for an astronomical context. The resulting data products are in turn interfaced to the clinical trials systems in use at the Cambridge Research Institute (Cancer Research-UK).
Sharrock, R; Gudjonsson, G H
1993-05-01
The main purpose of this study was to investigate the relationship between interrogative suggestibility and previous convictions among 108 defendants in criminal trials, using a path analysis technique. It was hypothesized that previous convictions, which may provide defendants with interrogative experiences, would correlate negatively with 'shift' as measured by the Gudjonsson Suggestibility Scale (Gudjonsson, 1984a), after intelligence and memory had been controlled for. The hypothesis was partially confirmed and the theoretical and practical implications of the findings are discussed.
Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M
2013-03-15
The minimum energy path (MEP) of the reaction, CF(3)CHFCF(3) + H → transition state (TS) → CF(3)CFCF(3) + H(2), has been computed at different ab initio levels and with density functional theory (DFT) using different functionals. The computed B3LYP/6-31++G**, BH&HLYP/cc-pVDZ, BMK/6-31++G**, M05/6-31+G**, M05-2X/6-31+G**, UMP2/6-31++G**, PUMP2/6-31++G**//UMP2/6-31++G**, RCCSD(T)/aug-cc-pVDZ//UMP2/6-31++G**, RCCSD(T)/aug-cc-pVTZ(spd,sp)//UMP2//6-31++G**, RCCSD(T)/CBS//M05/6-31+G**, and RCCSD(T)/CBS//UMP2/6-31++G** MEPs, and associated gradients and Hessians, were used in reaction rate coefficient calculations based on the transition state theory (TST). Reaction rate coefficients were computed between 300 and 1500 K at various levels of TST, which include conventional TST, canonical variational TST (CVT) and improved CVT (ICVT), and with different tunneling corrections, namely, Wigner, zero-curvature, and small-curvature (SCT). The computed rate coefficients obtained at different ab initio, DFT and TST levels are compared with experimental values available in the 1000-1200 K temperature range. Based on the rate coefficients computed at the ICVT/SCT level, the highest TST level used in this study, the BH&HLYP functional performs best among all the functionals used, while the RCCSD(T)/CBS//MP2/6-31++G** level is the best among all the ab initio levels used. Comparing computed reaction rate coefficients obtained at different levels of theory shows that, the computed barrier height has the strongest effect on the computed reaction rate coefficients as expected. Variational effects on the computed rate coefficients are found to be negligibly small. Although tunneling effects are relatively small at high temperatures (~1500 K), SCT corrections are significant at low temperatures (~300 K), and both barrier heights and the magnitudes of the imaginary frequencies affect SCT corrections. Copyright © 2012 Wiley Periodicals, Inc.
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.
NASA Astrophysics Data System (ADS)
Szefczyk, Borys; Claeyssens, Frederik; Mulholland, Adrian J.; Sokalski, W. Andrzej
We have performed a detailed, quantum chemical, decomposition analysis of the physical nature of key interactions in the model enzyme chorismate mutase (CM), for several active conformations produced by high level combined quantum mechanics/molecular mechanics (QM/MM) modeling. In opposition to our previous study, interactions between selected residues in the active site of CM were analysed along the whole reaction path, for several paths. The interaction energy is calculated up to Møller-Plesset second order level of theory and decomposed into physically meaningful components (electrostatic, exchange, delocalization, and electron correlation). This analysis shows, that the dominant interaction is differential stabilization by Arg90: this residue significantly stabilizes the transition state (TS) relative to the substrate in all the paths studied. Interactions in the active site of CM are dominated by the electrostatic component, whereas other components, for example electron correlation, are constant during reaction. Electrostatic effects alone are found to be responsible for lowering the barrier for reaction at the active site. Analysis of four reaction paths derived from QM/MM modeling shows that differences in the height of the barrier are due to differences in the electrostatic interactions of several weakly interacting residues. The influence of conformational effects, such as hydroxyl group rotation in the chorismate/TS, and the distance between Arg90 and the reacting chorismate, have also been analysed. The results show that specific conformations provide better activation barrier lowering. Even small changes in the conformation, like rotation of the hydroxyl group in chorismate (substrate), can significantly alter the activation barrier.0
Bayesian meta-analysis of Cronbach's coefficient alpha to evaluate informative hypotheses.
Okada, Kensuke
2015-12-01
This paper proposes a new method to evaluate informative hypotheses for meta-analysis of Cronbach's coefficient alpha using a Bayesian approach. The coefficient alpha is one of the most widely used reliability indices. In meta-analyses of reliability, researchers typically form specific informative hypotheses beforehand, such as 'alpha of this test is greater than 0.8' or 'alpha of one form of a test is greater than the others.' The proposed method enables direct evaluation of these informative hypotheses. To this end, a Bayes factor is calculated to evaluate the informative hypothesis against its complement. It allows researchers to summarize the evidence provided by previous studies in favor of their informative hypothesis. The proposed approach can be seen as a natural extension of the Bayesian meta-analysis of coefficient alpha recently proposed in this journal (Brannick and Zhang, 2013). The proposed method is illustrated through two meta-analyses of real data that evaluate different kinds of informative hypotheses on superpopulation: one is that alpha of a particular test is above the criterion value, and the other is that alphas among different test versions have ordered relationships. Informative hypotheses are supported from the data in both cases, suggesting that the proposed approach is promising for application.
CFD analysis of flow through Venturi tube and its discharge coefficient
NASA Astrophysics Data System (ADS)
Tukimin, A.; Zuber, M.; Ahmad, K. A.
2016-10-01
Venturi tube plays a very important role in different fields of engineering. It has a number of industrial applications in which its design is an essential factor. Venturi tube used in gas measurement applications provides an accurate critical gas flow measurement. There is a need to design Venturi tube with an effective analytical tool or software. In this work, two parameters: pressure drop and velocity discharge nozzle were analyzed using Computational Fluid Dynamics (CFD). The results obtained were then analyzed for accurate determination of the Venturi tube's discharge coefficient, Cd. It was found that there is less than 1% difference between the average values of the discharge coefficient obtained from the numerical analysis and experimental results.
PathGrid: a service-orientated architecture for microscopy image analysis.
Walton, N A; Brenton, J D; Caldas, C; Irwin, M J; Akram, A; Gonzalez-Solares, E; Lewis, J R; Maccallum, P H; Morris, L J; Rixon, G T
2010-08-28
This paper describes 'PathGrid'--an analysis and data integration system, developed initially to meet the demands in the analysis of medical microscopy imaging data. An overview of the current system is given, describing the techniques used in developing the data handling infrastructure and the analysis algorithm development. The use of software created in the context of systems designed for the astronomy domain is noted, specifically infrastructure from the astronomy virtual observatory movement for data discovery, access and workflow management, and astronomical image analysis software adapted for the analysis of high-throughput astronomy imaging surveys. This paper notes the applicability of the techniques from the astronomy domain. The testbed infrastructure deployment is described, emphasizing its speed and ease of use and support. The validity of the analysis techniques is confirmed through the pilot study described here--with the application to a large sample of immunohistochemistry microscopy data obtained in part for assessing the oestrogen receptor status of breast cancers. The analysis showed that the specificity and sensitivity values for the automatic scoring using PathGrid were within the errors of those obtained via a 'gold standard' manual pathologist scoring.
Morphological Awareness in Literacy Acquisition of Chinese Second Graders: A Path Analysis.
Zhang, Haomin
2016-02-01
The present study tested a path diagram regarding the contribution of morphological awareness (MA) to early literacy acquisition among Chinese-speaking second graders ([Formula: see text]). Three facets of MA were addressed, namely derivational awareness, compound awareness and compound structure awareness. The model aimed to test a theory of causal order among measures of MA and literacy outcomes. Drawing upon multivariate path analysis, direct and indirect effects of MA were analyzed to identify their role in literacy performance among young children. Results revealed that all three facets of MA made significant contributions to lexical inference ability. In addition, compound awareness showed a unique and significant contribution to vocabulary knowledge. It was also observed that lexical inference ability had a mediating effect predictive of both vocabulary knowledge and reading comprehension. Moreover, vocabulary knowledge mediated the effect of MA on reading comprehension. However, no significant contribution of MA to reading comprehension was found after controlling for lexical inference ability and vocabulary knowledge.
NASA Astrophysics Data System (ADS)
Dirba, I.; Kleperis, J.
2011-01-01
Analytical and numerical modelling is performed for the linear actuator of a parallel path magnet motor. In the model based on finite-element analysis, the 3D problem is reduced to a 2D problem, which is sufficiently precise in a design aspect and allows modelling the principle of a parallel path motor. The paper also describes a relevant numerical model and gives comparison with experimental results. The numerical model includes all geometrical and physical characteristics of the motor components. The magnetic flux density and magnetic force are simulated using FEMM 4.2 software. An experimental model has also been developed and verified for the core of switchable magnetic flux linear actuator and motor. The results of experiments are compared with those of theoretical/analytical and numerical modelling.
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 (P<0.001). After the sensitivity analysis, two studies were excluded, and the pooled r was -0.61 (95% CI: -0.66, -0.56) and was not significantly heterogeneous (P = 0.127). Regarding tumor type subgroup analysis, there were sufficient data to support a strong negative correlation 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.
Shiraishi, Fumihide; Sriyudthsak, Kansuporn; Suzuki, Yusuke
2010-02-01
This paper investigates the accuracy of a matrix method proposed by other researchers to calculate time-varying flux control coefficients (dynamic FCCs) from elasticity coefficients by means of summation and connectivity theorems in the framework of metabolic control analysis. A mathematical model for the fed-batch penicillin V fermentation process is used as a case example for discussion. Calculated results reveal that this method produces significant calculation errors because the theorems are essentially valid only in steady state, although it may provide rough time-transient behaviors of FCCs. Strictly, therefore, dynamic FCCs should be directly calculated from the differential equations for metabolite concentrations and sensitivities. Copyright (c) 2009 Elsevier Inc. All rights reserved.
Determination and analysis of distribution coefficients of 137Cs in soils from Biscay (Spain).
Elejalde, C; Herranz, M; Legarda, F; Romero, F
2000-10-01
The distribution coefficient of (137)Cs has been determined in 58 soils from 12 sampling points from Biscay by treating 10 g with 25 ml of an aqueous solution with an activity of 1765 Bq in the radionuclide, by shaking during 64 h and measuring the residual activity with a suitable detector. Soils were characterised by sampling depth, particle size analysis and the usual chemical parameters. Soils were thereafter treated to fix the chemical forms of (137)Cs speciation by successive extractions in order to determine fractions due to exchangeable, associated with carbonates, iron oxide and organic matter fractions, obtaining by difference the amount taken by the rest of the soil constituents. For this research, 16 soils from four points were selected from the previous samples. The greatest mean percentages of (137)Cs sorption were with the rest (69.93), exchangeable (13.17) and organic matter (12.54%) fractions. This paper includes also the calculation of partial distribution coefficients for chemical species as well as relations of distribution coefficients both among them and with soil parameters.
NASA Astrophysics Data System (ADS)
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.
Correlates of Unwanted Births in Bangladesh: A Study through Path Analysis.
Roy, Tapan Kumar; Singh, Brijesh P
2016-01-01
Unwanted birth is an important public health concern due to its negative association with adverse outcomes of mothers and children as well as socioeconomic development of a country. Although a number of studies have been investigated the determinants of unwanted births through logistic regression analysis, an extensive assessment using path model is lacking. In the current study, we applied path analysis to know the important covariates for unwanted births in Bangladesh. The study used data extracted from Bangladesh Demographic and Health Survey (BDHS) 2011. It considered sub-sample consisted of 7,972 women who had given most recent births five years preceding the date of interview or who were currently pregnant at survey time. Correlation analysis was used to find out the significant association with unwanted births. This study provided the factors affecting unwanted births in Bangladesh. The path model was used to determine the direct, indirect and total effects of socio-demographic factors on unwanted births. The result exhibited that more than one-tenth of the recent births were unwanted in Bangladesh. The differentials of unwanted births were women's age, education, age at marriage, religion, socioeconomic status, exposure of mass-media and use of family planning. In correlation analysis, it showed that unwanted births were positively correlated with women age and place of residence and these relationships were significant. On the contrary, unwanted births were inversely significantly correlated with education and social status. The total effects of endogenous variables such as women age, place of residence and use of family planning methods had favorable effect on unwanted births. Policymakers and program planners need to design programs and services carefully to reduce unwanted births in Bangladesh, especially, service should focus on helping those groups of women who were identified in the analysis as being at increased risks of unwanted births- older women
Correlates of Unwanted Births in Bangladesh: A Study through Path Analysis
Singh, Brijesh P.
2016-01-01
Background Unwanted birth is an important public health concern due to its negative association with adverse outcomes of mothers and children as well as socioeconomic development of a country. Although a number of studies have been investigated the determinants of unwanted births through logistic regression analysis, an extensive assessment using path model is lacking. In the current study, we applied path analysis to know the important covariates for unwanted births in Bangladesh. Methods The study used data extracted from Bangladesh Demographic and Health Survey (BDHS) 2011. It considered sub-sample consisted of 7,972 women who had given most recent births five years preceding the date of interview or who were currently pregnant at survey time. Correlation analysis was used to find out the significant association with unwanted births. This study provided the factors affecting unwanted births in Bangladesh. The path model was used to determine the direct, indirect and total effects of socio-demographic factors on unwanted births. Results The result exhibited that more than one-tenth of the recent births were unwanted in Bangladesh. The differentials of unwanted births were women’s age, education, age at marriage, religion, socioeconomic status, exposure of mass-media and use of family planning. In correlation analysis, it showed that unwanted births were positively correlated with women age and place of residence and these relationships were significant. On the contrary, unwanted births were inversely significantly correlated with education and social status. The total effects of endogenous variables such as women age, place of residence and use of family planning methods had favorable effect on unwanted births. Conclusion Policymakers and program planners need to design programs and services carefully to reduce unwanted births in Bangladesh, especially, service should focus on helping those groups of women who were identified in the analysis as being at
Silva, L A; Peixoto, L A; Teodoro, P E; Rodrigues, E V; Laviola, B G; Bhering, L L
2017-03-22
Jatropha is a species with great potential for biodiesel production, and the knowledge on how the main agronomic traits are correlated will contribute to its improvement. Therefore, the objectives of this study were to estimate the genetic parameters of the traits: plant height at 12 and 40 months, canopy projection on the row at 12 and 40 months, canopy projection between the row at 12 and 40 months, number of branches at 40 months, grain yield, and oil yield; to verify the existence of phenotypic correlation between these traits; to verify the influence of the morphological traits on oil yield by means of path analysis; and to evaluate the relationship between the productive traits in Jatropha and the morphological traits measured at different ages. Sixty-seven half-sib families were evaluated using a completely randomized block design with two replications and five plants per plot. Analysis of variance was used to estimate the genetic value. Phenotypic correlations were given by the Pearson correlation between traits. For the canonical correlation analysis, two groups of traits were established: group I, consisting of traits of economic importance for the culture, and group II, consisting of morphological traits. Path analysis was carried out considering oil yield as the main dependent variable. Genetic variability was observed among Jatropha families. Productive traits can be indirectly selected via morphological traits due to the correlation between these two groups of traits. Therefore, canonical correlations and path analysis are two strategies that may be useful in Jatropha-breeding program when the objective is to select productive traits via morphological traits.
On the Relation Between Projections of the Reweighted Path Ensemble
NASA Astrophysics Data System (ADS)
Bolhuis, Peter G.; Lechner, Wolfgang
2011-11-01
We derive several distribution functions for the recently introduced reweighted path ensemble [Rogal et al. in J. Chem. Phys. 133:174109, 2010]: the configurational and path densities, the reactive current, and the generalized committors for the different path types. We relate these distributions to the free energy and to the expressions for the rate constant in the transition state theory, the reactive flux method, the transition path (interface) sampling framework, and the Bayesian path statistics. In addition, we compute the transmission coefficient (distribution) from the reweighted path ensemble. Finally, we derive the path sampling shooting point distributions. For a simple two dimensional Langevin model we illustrate how these novel distributions can be used as analysis tools in rare event simulations.
Thermal optical path difference analysis of the telescope correct lens assembly
NASA Astrophysics Data System (ADS)
Hsu, Ming-Ying; Chang, Shenq-Tsong; Huang, Ting-Ming
2012-12-01
The effect of correct lens thermal optical path difference (OPD) on the optical performance of the Cassegrain telescope system is presented. The correct lens assembly includes several components such as a set of correct lenses, lens mount, spacer, mount barrel, and retainer. The heat transfer from the surrounding environment to the correct lens barrel will cause optical system aberration. The temperature distribution of the baffle is from 20.546°C to 21.485°C. Meanwhile, the off-axis ray's path of the OPD has taken the lens incidence point and emergence point into consideration. The correct lens temperature distribution is calculated by the lens barrel heat transfer analysis; the thermal distortion and stress are solved by the Finite Element Method (FEM) software. The temperature distribution is weighted to each incidence ray path, and the thermal OPD is calculated. The thermal OPD on the Z direction is transferred to optical aberration by fitting OPD into a rigid body motion and the Zernike polynomial. The aberration results can be used to evaluate the thermal effect on the correct lens assembly in the telescope system.
Error analysis of coefficient-based regularized algorithm for density-level detection.
Chen, Hong; Pan, Zhibin; Li, Luoqing; Tang, Yuanyan
2013-04-01
In this letter, we consider a density-level detection (DLD) problem by a coefficient-based classification framework with [Formula: see text]-regularizer and data-dependent hypothesis spaces. Although the data-dependent characteristic of the algorithm provides flexibility and adaptivity for DLD, it leads to difficulty in generalization error analysis. To overcome this difficulty, an error decomposition is introduced from an established classification framework. On the basis of this decomposition, the estimate of the learning rate is obtained by using Rademacher average and stepping-stone techniques. In particular, the estimate is independent of the capacity assumption used in the previous literature.
Numerical determination of lateral loss coefficients for subchannel analysis in nuclear fuel bundles
Sin Kim; Goon-Cherl Park
1995-09-01
An accurate prediction of cross-flow based on detailed knowledge of the velocity field in subchannels of a nuclear fuel assembly is of importance in nuclear fuel performance analysis. In this study, the low-Reynolds number {kappa}-{epsilon} turbulence model has been adopted in two adjacent subchannels with cross-flow. The secondary flow is estimated accurately by the anisotropic algebraic Reynolds stress model. This model was numerically calculated by the finite element method and has been verified successfully through comparison with existing experimental data. Finally, with the numerical analysis of the velocity field in such subchannel domain, an analytical correlation of the lateral loss coefficient is obtained to predict the cross-flow rate in subchannel analysis codes. The correlation is expressed as a function of the ratio of the lateral flow velocity to the donor subchannel axial velocity, recipient channel Reynolds number and pitch-to-diameter.
NASA Astrophysics Data System (ADS)
Acri, Antonio; Offner, Guenter; Nijman, Eugene; Rejlek, Jan
2016-10-01
Noise legislations and the increasing customer demands determine the Noise Vibration and Harshness (NVH) development of modern commercial vehicles. In order to meet the stringent legislative requirements for the vehicle noise emission, exact knowledge of all vehicle noise sources and their acoustic behavior is required. Transfer path analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. Transmission paths from different sources to target points of interest and their contributions can be analyzed by applying TPA. This technique is applied on test measurements, which can only be available on prototypes, at the end of the designing process. In order to overcome the limits of TPA, a numerical transfer path analysis methodology based on the substructuring of a multibody system is proposed in this paper. Being based on numerical simulation, this methodology can be performed starting from the first steps of the designing process. The main target of the proposed methodology is to get information of noise sources contributions of a dynamic system considering the possibility to have multiple forces contemporary acting on the system. The contributions of these forces are investigated with particular focus on distribute or moving forces. In this paper, the mathematical basics of the proposed methodology and its advantages in comparison with TPA will be discussed. Then, a dynamic system is investigated with a combination of two methods. Being based on the dynamic substructuring (DS) of the investigated model, the methodology proposed requires the evaluation of the contact forces at interfaces, which are computed with a flexible multi-body dynamic (FMBD) simulation. Then, the structure-borne noise paths are computed with the wave based method (WBM). As an example application a 4-cylinder engine is investigated and the proposed methodology is applied on the
NASA Astrophysics Data System (ADS)
Dong, Keqiang; Zhang, Hong; Gao, You
2017-01-01
Identifying the mutual interaction in aero-engine gas path system is a crucial problem that facilitates the understanding of emerging structures in complex system. By employing the multiscale multifractal detrended cross-correlation analysis method to aero-engine gas path system, the cross-correlation characteristics between gas path system parameters are established. Further, we apply multiscale multifractal detrended cross-correlation distance matrix and minimum spanning tree to investigate the mutual interactions of gas path variables. The results can infer that the low-spool rotor speed (N1) and engine pressure ratio (EPR) are main gas path parameters. The application of proposed method contributes to promote our understanding of the internal mechanisms and structures of aero-engine dynamics.
Wang, Nizhuan; Zeng, Weiming; Chen, Lei
2013-05-30
Independent component analysis (ICA) has been widely used in functional magnetic resonance imaging (fMRI) data to evaluate the functional connectivity, which assumes that the sources of functional networks are statistically independent. Recently, many researchers have demonstrated that sparsity is an effective assumption for fMRI signal separation. In this research, we present a sparse approximation coefficient-based ICA (SACICA) model to analyse fMRI data, which is a promising combination model of sparse features and an ICA technique. The SACICA method consists of three procedures. The wavelet packet decomposition procedure, which decomposes the fMRI data into wavelet tree nodes with different degrees of sparsity, is first. Then, the sparse approximation coefficients set formation procedure, in which an effective Lp norm is proposed to measure the sparse degree of the distinct wavelet tree nodes, is second. The ICA decomposition and reconstruction procedure, which utilises the sparse approximation coefficients set of the fMRI data, is last. The hybrid data experimental results demonstrated that the SACICA method exhibited the stronger spatial source reconstruction ability with respect to the unsmoothed fMRI data and better detection sensitivity of the functional signal on the smoothed fMRI data than the FastICA method. Furthermore, task-related experiments also revealed that SACICA was not only effective in discovering the functional networks but also exhibited a better detection sensitivity of the visual-related functional signal. In addition, the SACICA combined with Fast-FENICA proposed by Wang et al. (2012) was demonstrated to conduct the group analysis effectively on the resting-state data set.
Grech-Sollars, Matthew; Saunders, Dawn E; Phipps, Kim P; Clayden, Jonathan D; Clark, Chris A
2012-10-01
Embryonal brain tumors constitute a large and important subgroup of pediatric brain tumors. Apparent diffusion coefficient (ADC) measures have been previously used in the analysis of these tumors. We investigated a newly described ADC-derived parameter, the apparent transient coefficient in tumor (ATCT), a measure of the gradient change of ADC from the peri-tumoral edema into the tumor core, to study whether ATCT correlates with survival outcome. Sixty-one patients with histologically proven embryonal brain tumors and who had diffusion-weighted imaging (DWI) as part of their clinical imaging were enrolled in a retrospective study correlating ADC measures with survival. Kaplan-Meier survival curves were constructed for extent of surgical resection, age <3 years at diagnosis, tumor type, and metastasis at presentation. A multivariate survival analysis was performed that took into consideration ATCT and variables found to be significant in the Kaplan-Meier analysis as covariates. Results from the multivariate analysis showed that ATCT was the only significant covariate (P < .001). Survival analysis using Kaplan-Meier curves, dividing the patients into 4 groups of increasing values of ATCT, showed that more negative values of ATCT were significantly associated with a poorer prognosis (P < .001). A statistically significant difference was observed for survival data with respect to the change in ADC from edema into the tumor volume. Results show that more negative ATCT values are significantly associated with a poorer survival among children with embryonal brain tumors, irrespective of tumor type, extent of resection, age <3 years at diagnosis, and metastasis at presentation.
NASA Astrophysics Data System (ADS)
Selden, Nathaniel; Gimelshein, Natalia; Gimelshein, Sergey; Ketsdever, Andrew
2009-07-01
A method that connects measurements of radiometric forces on a heated vane in the transitional flow regime with the kinetic modeling of the flow, and derives the accommodation coefficients through the successive analysis of measured and computed results, is proposed. The method utilizes the fact that radiometric forces exerted on heated objects immersed in rarefied gases are governed by the interaction of gas molecules with the surface. Experimental results on radiometric forces on a 0.11 m diameter circular vane are obtained on a nano-Newton thrust stand in a 3 m long vacuum chamber for pressures ranging from approximately 0.01 to 1 Pa. The vane was heated to 419 K on the hot side and 396 K on the cold side. The numerical modeling is conducted using a combined ellipsoidal statistical Bhatnagar-Gross-Krook/direct simulation Monte Carlo approach that allows accurate and time efficient analysis of radiometric forces on a vane in large vacuum chambers filled with rarefied gas. Accommodation coefficients for the Maxwell model are estimated for argon, xenon, and helium on a machined aluminum surface, and found to be 0.81, 0.86, and 0.53, respectively.
Gajewski, Byron J; Lee, Robert; Thompson, Sarah; Dunton, Nancy; Becker, Annette; Wells, Valorie
2006-11-15
Path analytic models are useful tools in quantitative nursing research. They allow researchers to hypothesize causal inferential paths and test the significance of these paths both directly and indirectly through a mediating variable. A standard statistical method in the path analysis literature is to treat the variables as having a normal distribution and to estimate paths using several least squares regression equations. The parameters corresponding to the direct paths have point and interval estimates based on normal distribution theory. Indirect paths are a product of the direct path from the independent variable to the mediating variable and the direct path of the mediating variable to the dependent variable. However, in the case of non-normal distributions, the point and interval estimates of the indirect path become much more difficult to estimate. We address the issue of calculating indirect point and interval estimates in the case of non-normally distributed data. Our substantive application is a nursing home research problem in which the variables in the path analysis of interest involve variables with normal, Bernoulli, or Poisson distributions. Additionally, one of the Poisson variables is observed with error. This paper addresses estimating point and interval estimation of indirect paths for variables with non-normal distributions in the presence of missing data and measurement error. We handle these difficulties from a fully Bayesian point of view. We present our substantive path analysis motivated from a nursing home structure, process, and outcomes model. Our results focus on the impact job turnover in the nursing homes has on nursing home outcomes.
Free wake analysis of hover performance using a new influence coefficient method
NASA Technical Reports Server (NTRS)
Quackenbush, Todd R.; Bliss, Donald B.; Ong, Ching Cho; Ching, Cho Ong
1990-01-01
A new approach to the prediction of helicopter rotor performance using a free wake analysis was developed. This new method uses a relaxation process that does not suffer from the convergence problems associated with previous time marching simulations. This wake relaxation procedure was coupled to a vortex-lattice, lifting surface loads analysis to produce a novel, self contained performance prediction code: EHPIC (Evaluation of Helicopter Performance using Influence Coefficients). The major technical features of the EHPIC code are described and a substantial amount of background information on the capabilities and proper operation of the code is supplied. Sample problems were undertaken to demonstrate the robustness and flexibility of the basic approach. Also, a performance correlation study was carried out to establish the breadth of applicability of the code, with very favorable results.
NASA Astrophysics Data System (ADS)
Baek, Jieun; Choi, Yosoon
2017-04-01
Most algorithms for least-cost path analysis usually calculate the slope gradient between the source cell and the adjacent cells to reflect the weights for terrain slope into the calculation of travel costs. However, these algorithms have limitations that they cannot analyze the least-cost path between two cells when obstacle cells with very high or low terrain elevation exist between the source cell and the target cell. This study presents a new algorithm for least-cost path analysis by correcting digital elevation models of natural landscapes to find possible paths satisfying the constraint of maximum or minimum slope gradient. The new algorithm calculates the slope gradient between the center cell and non-adjacent cells using the concept of extended move-sets. If the algorithm finds possible paths between the center cell and non-adjacent cells with satisfying the constraint of slope condition, terrain elevation of obstacle cells existing between two cells is corrected from the digital elevation model. After calculating the cumulative travel costs to the destination by reflecting the weight of the difference between the original and corrected elevations, the algorithm analyzes the least-cost path. The results of applying the proposed algorithm to the synthetic data sets and the real-world data sets provide proof that the new algorithm can provide more accurate least-cost paths than other conventional algorithms implemented in commercial GIS software such as ArcGIS.
Evaluation of dispersivity coefficients by means of a laboratory image analysis
NASA Astrophysics Data System (ADS)
Citarella, Donato; Cupola, Fausto; Tanda, Maria Giovanna; Zanini, Andrea
2015-01-01
This paper describes the application of an innovative procedure that allows the estimation of longitudinal and transverse dispersivities in an experimental plume devised in a laboratory sandbox. The phenomenon of transport in porous media is studied using sodium fluorescein as tracer. The fluorescent excitation was achieved by using blue light and the concentration data were obtained through the processing of side wall images collected with a high resolution color digital camera. After a calibration process, the relationship between the luminosity of the emitted fluorescence and the fluorescein concentration was determined at each point of the sandbox. The relationships were used to describe the evolution of the transport process quantitatively throughout the entire domain. Some check tests were performed in order to verify the reliability of the experimental device. Numerical flow and transport models of the sandbox were developed and calibrated comparing computed and observed flow rates and breakthrough curves. The estimation of the dispersivity coefficients was carried out by analyzing the concentration field deduced from the images collected during the experiments; the dispersivity coefficients were evaluated in the domain zones where the tracer affected the porous medium under the hypothesis that the transport phenomenon is described by advection-dispersion equation (ADE) and by computing the differential components of the concentration by means of a numerical leap-frog scheme. The values determined agree with the ones referred in literature for similar media and with the coefficients obtained by calibrating the numerical model. Very interesting considerations have been made from the analysis of the performance of the methodology at different locations in the flow domain and phases of the plume evolution.
NASA Technical Reports Server (NTRS)
Bogert, Philip B.; Satyanarayana, Arunkumar; Chunchu, Prasad B.
2006-01-01
Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.
Yu, Liyang; Han, Qi; Niu, Xiamu; Yiu, S M; Fang, Junbin; Zhang, Ye
2016-02-01
Most of the existing image modification detection methods which are based on DCT coefficient analysis model the distribution of DCT coefficients as a mixture of a modified and an unchanged component. To separate the two components, two parameters, which are the primary quantization step, Q1, and the portion of the modified region, α, have to be estimated, and more accurate estimations of α and Q1 lead to better detection and localization results. Existing methods estimate α and Q1 in a completely blind manner, without considering the characteristics of the mixture model and the constraints to which α should conform. In this paper, we propose a more effective scheme for estimating α and Q1, based on the observations that, the curves on the surface of the likelihood function corresponding to the mixture model is largely smooth, and α can take values only in a discrete set. We conduct extensive experiments to evaluate the proposed method, and the experimental results confirm the efficacy of our method.
Yuan, Xian-Zheng; Shi, Xiao-Shuang; Yuan, Chun-Xin; Wang, Yu-Ping; Qiu, Yan-Ling; Guo, Rong-Bo; Wang, Li-Sheng
2014-02-01
In order to facilitate the application of Anaerobic Digestion Model No. 1 (ADM1), an approach for a detailed calculation of stoichiometric coefficients for amino acids acidogenesis during the anaerobic digestion of blue algae is presented. The simulation results obtained support the approach by good predictions of the dynamic behavior of cumulative methane production, pH values as well as the concentrations of acetate, propionate, butyrate, valerate and inorganic nitrogen. The sensitivity analysis based on Monte Carlo simulation showed that the stoichiometric coefficients for amino acids acidogenesis had high sensitivities to the outputs of the model. The model further indicated that the Gibbs free energies from the uptake of long-chain fatty acids (LCFA), valerate and butyrate were positive through the digestion, while the free energies for other components were negative. During the digestion, the cumulative heat productions from microbial activities and methane were 77.69 kJ and 185.76 kJ, respectively. This result suggested that proper heat preservation of anaerobic digesters could minimize the external heating needs due to the heat produced from microbial activities. Copyright © 2013 Elsevier Ltd. All rights reserved.
The Land Gini Coefficient and Its Application for Land Use Structure Analysis in China
Zheng, Xinqi; Xia, Tian; Yang, Xin; Yuan, Tao; Hu, Yecui
2013-01-01
We introduce the Gini coefficient to assess the rationality of land use structure. The rapid transformation of land use in China provides a typical case for land use structure analysis. In this study, a land Gini coefficient (LGC) analysis tool was developed. The land use structure rationality was analyzed and evaluated based on statistical data for China between 1996 and 2008. The results show: (1)The LGC of three major land use types–farmland, built-up land and unused land–was smaller when the four economic districts were considered as assessment units instead of the provinces. Therefore, the LGC is spatially dependent; if the calculation unit expands, then the LGC decreases, and this relationship does not change with time. Additionally, land use activities in different provinces of a single district differed greatly. (2) At the national level, the LGC of the three main land use types indicated that during the 13 years analyzed, the farmland and unused land were evenly distributed across China. However, the built-up land distribution was relatively or absolutely unequal and highlights the rapid urbanization in China. (3) Trends in the distribution of the three major land use types are very different. At the national level, when using a district as the calculation unit, the LGC of the three main land use types increased, and their distribution became increasingly concentrated. However, when a province was used as the calculation unit, the LGC of the farmland increased, while the LGC of the built-up and unused land decreased. These findings indicate that the distribution of the farmland became increasingly concentrated, while the built-up land and unused land became increasingly uniform. (4) The LGC analysis method of land use structure based on geographic information systems (GIS) is flexible and convenient. PMID:24130764
NASA Astrophysics Data System (ADS)
van Lew, Baldur; Botha, Charl P.; Milles, Julien R.; Vrooman, Henri A.; van de Giessen, Martijn; Lelieveldt, Boudewijn P. F.
2015-03-01
The cohort size required in epidemiological imaging genetics studies often mandates the pooling of data from multiple hospitals. Patient data, however, is subject to strict privacy protection regimes, and physical data storage may be legally restricted to a hospital network. To enable biomarker discovery, fast data access and interactive data exploration must be combined with high-performance computing resources, while respecting privacy regulations. We present a system using fast and inherently secure light-paths to access distributed data, thereby obviating the need for a central data repository. A secure private cloud computing framework facilitates interactive, computationally intensive exploration of this geographically distributed, privacy sensitive data. As a proof of concept, MRI brain imaging data hosted at two remote sites were processed in response to a user command at a third site. The system was able to automatically start virtual machines, run a selected processing pipeline and write results to a user accessible database, while keeping data locally stored in the hospitals. Individual tasks took approximately 50% longer compared to a locally hosted blade server but the cloud infrastructure reduced the total elapsed time by a factor of 40 using 70 virtual machines in the cloud. We demonstrated that the combination light-path and private cloud is a viable means of building an analysis infrastructure for secure data analysis. The system requires further work in the areas of error handling, load balancing and secure support of multiple users.
Path analysis for adherence to pelvic floor muscle exercise among women with urinary incontinence.
Chen, Shu-Yueh; Tzeng, Ya-Ling
2009-06-01
This study developed and tested the accuracy of a model designed to predict adherence to a pelvic floor muscle exercise regimen by Taiwanese women with urinary incontinence. The sample was composed of 106 women treated for urinary incontinence at urban hospitals in central and northern Taiwan from April 2000 to March 2003. All participants had practiced prescribed pelvic floor muscle exercises for at least 6 weeks at the time they completed study measures, which included adherence to pelvic floor muscle exercise, self-efficacy for the exercise, knowledge of the exercise, attitudes toward the exercise, dyadic cohesion, perceived benefits of the exercise, and severity of urine loss. After stepwise multiple regression analysis, a path analysis was conducted, with significant paths retained as modifiers. Self-efficacy for pelvic floor muscle exercise strongly and directly affected adherence to the exercise regimen. Attitudes toward the exercise, dyadic cohesion, and perceived benefits of the exercise affected adherence when mediated by self-efficacy for pelvic floor muscle exercise. Severity of urine loss also directly affected adherence. Exercise knowledge affected neither self-efficacy nor adherence. The model fit the data and accounted for 40% of adherence variance. Findings affirm the significant role of self-efficacy in predicting adherence to pelvic floor muscle exercise. Thus, self-efficacy for exercise can be an indicator for nurses to tailor exercise-training programs for women with urinary incontinence. Nurses can use the study findings to develop interventions to increase women's adherence to the exercise.
Ghasemi, Fakhradin; Kalatpour, Omid; Moghimbeigi, Abbas; Mohhamadfam, Iraj
2017-04-26
Unsafe behavior is closely related to occupational accidents. Work pressure is one the main factors affecting employees' behavior. The aim of the present study was to provide a path analysis model for explaining how work pressure affects safety behavior. Using a self-administered questionnaire, six variables supposed to affect safety employees' behavior were measured. The path analysis model was constructed based on several hypotheses. The goodness of fit of the model was assessed using both absolute and comparative fit indices. Work pressure was determined not to influence safety behavior directly. However, it negatively influenced other variables. Group attitude and personal attitude toward safety were the main factors mediating the effect of work pressure on safety behavior. Among the variables investigated in the present study, group attitude, personal attitude and work pressure had the strongest effects on safety behavior. Managers should consider that in order to improve employees' safety behavior, work pressure should be reduced to a reasonable level, and concurrently a supportive environment, which ensures a positive group attitude toward safety, should be provided. Replication of the study is recommended.
Genetic parameters and path analysis in cowpea genotypes grown in the Cerrado/Pantanal ecotone.
Lopes, K V; Teodoro, P E; Silva, F A; Silva, M T; Fernandes, R L; Rodrigues, T C; Faria, T C; Corrêa, A M
2017-05-18
Estimating genetic parameters in plant breeding allows us to know the population potential for selecting and designing strategies that can maximize the achievement of superior genotypes. The objective of this study was to evaluate the genetic potential of a population of 20 cowpea genotypes by estimating genetic parameters and path analysis among the traits to guide the selection strategies. The trial was conducted in randomized block design with four replications. Its morphophysiological components, components of green grain production and dry grain yield were estimated from genetic use and correlations between the traits. Phenotypic correlations were deployed through path analysis into direct and indirect effects of morphophysiological traits and yield components on dry grain yield. There were significant differences (P < 0.01) between the genotypes for most the traits, indicating the presence of genetic variability in the population and the possibility of practicing selection. The population presents the potential for future genetic breeding studies and is highly promising for the selection of traits dry grain yield, the number of grains per pod, and hundred grains mass. A number of grains per green pod is the main determinant trait of dry grain yield that is also influenced by the cultivar cycle and that the selection for the dry grain yield can be made indirectly by selecting the green pod mass and green pod length.
Laser-Induced Breakdown Spectroscopy in open-path configuration for the analysis of distant objects
NASA Astrophysics Data System (ADS)
Sallé, B.; Mauchien, P.; Maurice, S.
2007-08-01
A review of recent results on stand-off Laser-Induced Breakdown Spectroscopy (LIBS) analysis and applications is presented. Stand-off LIBS was suggested for elemental analysis of materials located in environments where any physical access was not possible but optical access could be envisaged. This review only refers to the use of the open-path LIBS configuration in which the laser beam and the returning plasma light are transmitted through the atmosphere. It does not present the results obtained with a transportation of the laser pulses to the target through an optical fiber. Open-path stand-off LIBS has mainly been used with nanosecond laser pulses for solid sample analysis at distances of tens of meters. Liquid samples have also been analyzed at distances of a few meters. The distances achievable depend on many parameters including the laser characteristics (pulse energy and power, beam divergence, spatial profile) and the optical system used to focus the pulses at a distance. A large variety of laser focusing systems have been employed for stand-off analysis comprising refracting or reflecting telescope. Efficient collection of the plasma light is also needed to obtain analytically useful signals. For stand-off LIBS analysis, a lens or a mirror is required to increase the solid angle over which the plasma light can be collected. The light collection device can be either at an angle from the laser beam path or collinear with the optical axis of the system used to focus the laser pulses on the target surface. These different configurations have been used depending on the application such as rapid sorting of metal samples, identification of material in nuclear industry, process control and monitoring in metallurgical industry, applications in future planetary missions, detection of environmental contamination or cleaning of objects of cultural heritage. Recent stand-off analyses of metal samples have been reported using femtosecond laser pulses to extend LIBS
Vereecken, H; Vanderborght, J; Kasteel, R; Spiteller, M; Schäffer, A; Close, M
2011-01-01
In this study, we analyzed sorption parameters for pesticides that were derived from batch and column or batch and field experiments. The batch experiments analyzed in this study were run with the same pesticide and soil as in the column and field experiments. We analyzed the relationship between the pore water velocity of the column and field experiments, solute residence times, and sorption parameters, such as the organic carbon normalized distribution coefficient ( ) and the mass exchange coefficient in kinetic models, as well as the predictability of sorption parameters from basic soil properties. The batch/column analysis included 38 studies with a total of 139 observations. The batch/field analysis included five studies, resulting in a dataset of 24 observations. For the batch/column data, power law relationships between pore water velocity, residence time, and sorption constants were derived. The unexplained variability in these equations was reduced, taking into account the saturation status and the packing status (disturbed-undisturbed) of the soil sample. A new regression equation was derived that allows estimating the values derived from column experiments using organic matter and bulk density with an value of 0.56. Regression analysis of the batch/column data showed that the relationship between batch- and column-derived values depends on the saturation status and packing of the soil column. Analysis of the batch/field data showed that as the batch-derived value becomes larger, field-derived values tend to be lower than the corresponding batch-derived values, and vice versa. The present dataset also showed that the variability in the ratio of batch- to column-derived value increases with increasing pore water velocity, with a maximum value approaching 3.5.
Hierarchy of Dysfunction Related to Dressing Performance in Stroke Patients: A Path Analysis Study
Fujita, Takaaki; Nagayama, Hirofumi; Sato, Atsushi; Yamamoto, Yuichi; Yamane, Kazuhiro; Otsuki, Koji; Tsuchiya, Kenji; Tozato, Fusae
2016-01-01
Previous reports indicated that various dysfunctions caused by stroke affect the level of independence in dressing. These dysfunctions can be hierarchical, and these effects on dressing performance can be complicated in stroke patients. However, there are no published reports focusing on the hierarchical structure of the relationships between the activities of daily living and balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits. The purpose of this study was to elucidate the hierarchical and causal relationships between dressing performance and these dysfunctions in stroke patients. This retrospective study included 104 first-time stroke patients. The causal relationship between the dressing performance and age, time post stroke, balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits were examined using path analysis. A hypothetical path model was created based on previous studies, and the goodness of fit between the data and model were verified. A modified path model was created that achieved an almost perfect fit to the data. Balance function and abdominal muscle strength have direct effects on dressing performance, with standardized direct effect estimates of 0.78 and 0.15, respectively. Age, motor and sensory functions of the affected lower limb, and strength of abdominal muscle and knee extension on the unaffected side have indirect effects on dressing by influencing balance function. Our results suggest that dressing performance depends strongly on balance function, and it is mainly influenced by the motor function of the affected lower limb. PMID:26954499
NASA Astrophysics Data System (ADS)
Mockler, Eva M.; O'Loughlin, Fiachra E.; Bruen, Michael
2016-05-01
Increasing pressures on water quality due to intensification of agriculture have raised demands for environmental modeling to accurately simulate the movement of diffuse (nonpoint) nutrients in catchments. As hydrological flows drive the movement and attenuation of nutrients, individual hydrological processes in models should be adequately represented for water quality simulations to be meaningful. In particular, the relative contribution of groundwater and surface runoff to rivers is of interest, as increasing nitrate concentrations are linked to higher groundwater discharges. These requirements for hydrological modeling of groundwater contribution to rivers initiated this assessment of internal flow path partitioning in conceptual hydrological models. In this study, a variance based sensitivity analysis method was used to investigate parameter sensitivities and flow partitioning of three conceptual hydrological models simulating 31 Irish catchments. We compared two established conceptual hydrological models (NAM and SMARG) and a new model (SMART), produced especially for water quality modeling. In addition to the criteria that assess streamflow simulations, a ratio of average groundwater contribution to total streamflow was calculated for all simulations over the 16 year study period. As observations time-series of groundwater contributions to streamflow are not available at catchment scale, the groundwater ratios were evaluated against average annual indices of base flow and deep groundwater flow for each catchment. The exploration of sensitivities of internal flow path partitioning was a specific focus to assist in evaluating model performances. Results highlight that model structure has a strong impact on simulated groundwater flow paths. Sensitivity to the internal pathways in the models are not reflected in the performance criteria results. This demonstrates that simulated groundwater contribution should be constrained by independent data to ensure results
Hong, Ki Hwan; Lim, Yong Gyu; Park, Kwang Suk
2009-12-01
We present a new method measuring body impedance using a thigh-to-thigh current path, which can reflect the abdominal fat portion more sensitively and can be conveniently applied during the daily use on a toilet seat. Two pairs of electrodes were installed on a toilet seat to provide current and to permit voltage measurement through a thigh-to-thigh current path. The effectiveness of the method was compared with conventional foot-to-foot and hand-to-foot current paths by simulation and by experiments referenced to computed tomography (CT) image analysis. Body impedance using three different current paths was measured, and abdominal CT images were acquired for eight subjects. Measured body impedances were compared with the visceral to subcutaneous fat ratio (VF/SF) calculated from the CT-determined abdominal fat volume. The thigh-to-thigh current path was about 75% more sensitive in abdominal fat measurement than the conventional current paths in simulation experiments and displayed a higher VF/SF correlation (r = 0.768) than the foot-to-foot (r = 0.425) and hand-to-foot (r = 0.497) current paths.
NASA Astrophysics Data System (ADS)
Lin, Cheng-Shian; Tsay, Jyh-Jong
2016-05-01
Passive forgery detection aims to detect traces of image tampering without the need for prior information. With the increasing demand for image content protection, passive detection methods able to identify image tampering areas are increasingly needed. However, most current passive approaches either work only for image-level JPEG compression detection and cannot localize region-level forgery, or suffer from high-false detection rates in localizing altered regions. This paper proposes an effective approach based on discrete cosine transform coefficient analysis for the detection and localization of altered regions of JPEG compressed images. This approach can also work with altered JPEG images resaved in JPEG compressed format with different quality factors. Experiments with various tampering methods such as copy-and-paste, image completion, and composite tampering, show that the proposed approach is able to effectively detect and localize altered areas and is not sensitive to image contents such as edges and textures.
Liu, Xuan; Ramella-Roman, Jessica C.; Huang, Yong; Guo, Yuan; Kang, Jin U.
2013-01-01
In this study, we proposed 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 validated our model and used the simulation method to study the statistical properties of cross-correlation coefficients (XCC) between Ascans which have been recently applied in transverse motion analysis by our group. The results of simulation show that over sampling is essential for accurate motion tracking; exponential decay of OCT signal leads to an under estimate of motion which can be corrected; lateral heterogeneity of sample leads to an over estimate of motion for a few pixels corresponding to the structural boundary. PMID:23456001
Small, J R
1993-01-01
This paper is a study into the effects of experimental error on the estimated values of flux control coefficients obtained using specific inhibitors. Two possible techniques for analysing the experimental data are compared: a simple extrapolation method (the so-called graph method) and a non-linear function fitting method. For these techniques, the sources of systematic errors are identified and the effects of systematic and random errors are quantified, using both statistical analysis and numerical computation. It is shown that the graph method is very sensitive to random errors and, under all conditions studied, that the fitting method, even under conditions where the assumptions underlying the fitted function do not hold, outperformed the graph method. Possible ways of designing experiments to minimize the effects of experimental errors are analysed and discussed. PMID:8257434
Analysis of rotordynamic coefficients of helically-grooved turbulent annular seals
NASA Technical Reports Server (NTRS)
Kim, C.-H.; Childs, D. W.
1986-01-01
An analysis for helically-grooved turbulent annular seals is developed to predict leakage and dynamic coefficients, as related to rotordynamics. The grooved surface pattern is formulated as an inhomogeneous directivity in surface shear stress. The zeroth-order equations define the steady-state leakage and the circumferential velocity development due to wall shear for a centered rotor position. The first-order equations define perturbations in the pressure and axial and circumferential velocity fields due to small motion of the rotor about the centered position. Numerical results are presented for proposed grooved seals in the High Pressure Oxygen Turbopump (HPTOP) of the Space Shuttle Main Engine (SSME) and for a water-pump application. The results show that an optimum helix angle exists from a rotordynamic stability viewpoint. Further, a properly designed helically-grooved stator is predicted to have pronounced stability advantages over other currently used seals.
NASA Astrophysics Data System (ADS)
Kikuchi, Yuta; Tsumura, Kyosuke; Kunihiro, Teiji
2016-05-01
We give a quantitative analysis of the dynamical properties of fermionic cold atomic gases in normal phase, such as the shear viscosity, heat conductivity, and viscous relaxation times, using the novel microscopic expressions derived by the renormalization group (RG) method, where the Boltzmann equation is faithfully solved to extract the hydrodynamics without recourse to any ansatz. In particular, we examine the quantum statistical effects, temperature dependence, and scattering-length dependence of the transport coefficients and the viscous relaxation times. The numerical calculation shows that the relation τπ = η / P, which is derived in the relaxation-time approximation (RTA) and is used in most of the literature, turns out to be satisfied quite well, while the similar relation for the viscous relaxation time τJ of the heat conductivity is satisfied only approximately with a considerable error.
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.
Seynaeve, Bert; Rosseel, Eveline; Nicolai, Bart; Vandewalle, Stefan . E-mail: Stefan.Vandewalle@cs.kuleuven.be
2007-05-20
Partial differential equations with random coefficients appear for example in reliability problems and uncertainty propagation models. Various approaches exist for computing the stochastic characteristics of the solution of such a differential equation. In this paper, we consider the spectral expansion approach. This method transforms the continuous model into a large discrete algebraic system. We study the convergence properties of iterative methods for solving this discretized system. We consider one-level and multi-level methods. The classical Fourier mode analysis technique is extended towards the stochastic case. This is done by taking the eigenstructure into account of a certain matrix that depends on the random structure of the problem. We show how the convergence properties depend on the particulars of the algorithm, on the discretization parameters and on the stochastic characteristics of the model. Numerical results are added to illustrate some of our theoretical findings.
NASA Astrophysics Data System (ADS)
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.
Gaussian white noise analysis and its application to Feynman path integral
NASA Astrophysics Data System (ADS)
Suryawan, Herry Pribawanto
2016-02-01
In applied science, Gaussian white noise (the time derivative of Brownian motion) is often chosen as a mathematical idealization of phenomena involving sudden and extremely large fluctuations. It is also possible to define and study Gaussian white noise in a mathematically rigorous framework. In this survey paper we review the Gaussian white noise as an object in an infinite dimensional topological vector space. A brief construction of Gaussian white noise space and Gaussian white noise distributions will be presented. Gaussian white noise analysis provides a framework which offers various generalization of concept known from finite dimensional analysis to the infinite dimensional case, among them are differential operators, Fourier transform, and distribution theory. We will also present some recent developments and results on the application of Gaussian white noise theory to Feynman's path integral approach for quantum mechanics.
[Monitoring and analysis of CO2 and CH4 using long path FTIR spectroscopy over Beijing].
Xu, Liang; Liu, Jian-guo; Gao, Min-guang; Lu, Yi-huai; Liu, Wen-qing; Wei, Xiu-li; Zhu, Jun; Zhang, Tian-shu; Chen, Jun
2007-05-01
Recently, the greenhouse effect is well known and is of great worldwide concern. CO2 and CH4 are two of the main human activity-induced greenhouse gases in the atmosphere. It is important for environmental scientists to monitor their long-term variation. A Fourier transform infrared spectrometer was used to monitor the concentrations of CO2 and CH4 at a specific site in Beijing. The pollution air was passed through a long open path and the absorption spectra were collected over a period of a month. Quantitative analysis was performed by means of the nonlinear least square method using synthetically generated spectra, which was than convolved with instrumental line shape function. Ambient levels of CO2 and CH4 are reported with a time resolution of five minutes for 4-10, September 2005, and some analysis is present.
Use of the varying coefficient model in an exercise and depression meta-analysis.
Kelley, George A; Kelley, Kristi S
2012-06-26
Use a recently developed varying coefficient model to determine the effects of exercise in adults with depression. Data from a recent meta-analysis addressing the effects of exercise on depression in adults were used. Studies were limited to randomized controlled intervention trials of any type of chronic exercise (for example, walking and jogging) in adults greater than or equal to 18 years of age with a diagnosis of depression. For each study, the standardized mean difference (exercise minus control) effect size for depression, adjusted for small-sample bias, was calculated. Variance statistics for each effect size and pooling of results were calculated using the recently proposed varying coefficient (VC) model for standardized mean differences. Standardized effect-sizes of 0.20, 0.50 and 0.80 were considered to represent small, medium and large effects. Results were considered statistically significant if the 95% confidence intervals did not cross 0, with negative results indicative of reductions in depression. These findings were then compared with results using traditional random-effects (RE) models. A total of 23 studies representing 907 men and women (476 exercise, 431 control) were pooled for analysis. Both RE and VC models resulted in large, statistically significant improvements in depression as a result of exercise in adults. However, the VC model resulted in a larger overall effect size as well as confidence intervals that were narrower than previously reported using the RE model. The overall mean effect size for the RE model was -0.82 with a 95% confidence interval of -1.12 to -0.51. For the VC model, overall mean effect size was -0.88 with a 95% confidence interval of -1.08 to -0.68. The relative difference between the RE and VC approaches was 7.3%. The VC model, a potentially preferable model, confirms the positive effects of exercise on depression in adults.
NASA Astrophysics Data System (ADS)
Scholtes, Ingo; Wider, Nicolas; Garas, Antonios
2016-03-01
Despite recent advances in the study of temporal networks, the analysis of time-stamped network data is still a fundamental challenge. In particular, recent studies have shown that correlations in the ordering of links crucially alter causal topologies of temporal networks, thus invalidating analyses based on static, time-aggregated representations of time-stamped data. These findings not only highlight an important dimension of complexity in temporal networks, but also call for new network-analytic methods suitable to analyze complex systems with time-varying topologies. Addressing this open challenge, here we introduce a novel framework for the study of path-based centralities in temporal networks. Studying betweenness, closeness and reach centrality, we first show than an application of these measures to time-aggregated, static representations of temporal networks yields misleading results about the actual importance of nodes. To overcome this problem, we define path-based centralities in higher-order aggregate networks, a recently proposed generalization of the commonly used static representation of time-stamped data. Using data on six empirical temporal networks, we show that the resulting higher-order measures better capture the true, temporal centralities of nodes. Our results demonstrate that higher-order aggregate networks constitute a powerful abstraction, with broad perspectives for the design of new, computationally efficient data mining techniques for time-stamped relational data.
Wang, Jin-Yu; Chu, Jie; Sun, Shi-Hua; Zhang, Jie; Guo, Xiao-Lei; Jia, Cun-Xian
2017-01-01
This study explores the effects of social psychological factors on suicidal intent among suicide attempters in rural China. Suicide attempters were identified by the county-level Centers for Disease Control and Prevention (CDCs) and interviewed by the research team. A path analysis was conducted with physical illness, social support, and negative life events as exogenous variables, and life satisfaction, depressive emotions, and suicidal intent as endogenous variables. Beginning with a saturation model, a best model was obtained after removing the paths that were not significant. In the final model, depressive emotions and life satisfaction were directly associated with suicidal intent, and the standardized effect estimates were 0.3007 (p < 0.001) and -0.1182 (p = 0.0368). Physical illness, social support, and negative life events did not directly affect suicidal intent but had indirect effect. Depressive emotions may be the most important and direct predictor of suicidal intent; physical illness, negative life events, and social support affect suicidal intent through life satisfaction and depressive emotions.
Analysis of Two-Phase Path Management Scheme for MPLS Traffic Engineering
NASA Astrophysics Data System (ADS)
Tamura, Hitomi; Kawahara, Kenji; Oie, Yuji
Traffic Engineering (TE) is important for improving QoS in forwarding paths by efficient use of network resources. In fact, MPLS allows several detour paths to be (pre-)established for some source-destination pair as well as its primary path of minimum hops. Thus, we focus on a two-phase path management scheme using these two kinds of paths. In the first phase, each primary path is allocated to a flow on a specific source-destination pair if the path is not congested, i.e., if its utilization is less than some predetermined threshold; otherwise, as the second phase, one of the detour paths is allocated randomly if the path is available. Therefore, in this paper, we analytically evaluate this path management scheme by extending the M/M/c/c queueing system, and through some numerical results we investigate the impact of a threshold on the flow-blocking probability. Through some numerical results, we discuss the adequacy of the path management scheme for MPLS-TE.
NASA Technical Reports Server (NTRS)
Childs, D. W.
1983-01-01
An improved theory for the prediction of the rotordynamic coefficients of turbulent annular seals was developed. Predictions from the theory are compared to the experimental results and an approach for the direct calculation of empirical turbulent coefficients from test data are introduced. An improved short seal solution is shown to do a better job of calculating effective stiffness and damping coefficients than either the original short seal solution or a finite length solution. However, the original short seal solution does a much better job of predicting equivalent added mass coefficient.
NASA Astrophysics Data System (ADS)
Mashayekhi, Mohammad Jalali; Behdinan, Kamran
2017-10-01
The increasing demand to minimize undesired vibration and noise levels in several high-tech industries has generated a renewed interest in vibration transfer path analysis. Analyzing vibration transfer paths within a system is of crucial importance in designing an effective vibration isolation strategy. Most of the existing vibration transfer path analysis techniques are empirical which are suitable for diagnosis and troubleshooting purpose. The lack of an analytical transfer path analysis to be used in the design stage is the main motivation behind this research. In this paper an analytical transfer path analysis based on the four-pole theory is proposed for multi-energy-domain systems. Bond graph modeling technique which is an effective approach to model multi-energy-domain systems is used to develop the system model. In this paper an electro-mechanical system is used as a benchmark example to elucidate the effectiveness of the proposed technique. An algorithm to obtain the equivalent four-pole representation of a dynamical systems based on the corresponding bond graph model is also presented in this paper.
NASA Astrophysics Data System (ADS)
Lukacs, B.; Berczi, Sz.
1997-03-01
On the basis of the new Catalog of Antarctic Meteorites (Yanai, Kojima, Haramura, 1995) we carried out statistical analysis on the bulk composition of chondrites (of the 2987 classified chondrites on 403 samples). From averages of van Schmus-Wood petrologic classes (vSW-pc), we have projected paths of thermal evolution of chondritic parent bodies of E, H, L and LL types. Transformations in the ferrous compounds were projected to the vSW-table, then their changes between the vSW-pc stages were projected to the compositional field of the Fe + FeS vs Fe-oxides diagram. There the sequence of vSW-pc averages (representing higher and higher heat-impact with increasing vSW-pc numbers) formed an oxidation and reduction series from the initial reduction (for all types) through reoxidation (for H, L, LL types) until final outflow of iron (for L and LL types).
A path analysis of reading comprehension for adults with low literacy
Mellard, Daryl F.; Fall, Emily; Woods, Kari L.
2010-01-01
Adult literacy interventions often rely on models of reading validated with children or adult populations with a broad range of reading. Such models do not fully satisfy the need for intervention research and development for adults with low literacy. Thus, the authors hypothesized that a model representing the relationship between reading component skills would be predictive of reading comprehension for an adult population with low literacy and beneficial to adult literacy researchers. Using data from 174 adults participating in adult basic education and secondary education programs, the authors performed a path analysis of component skills' contribution to reading comprehension. The findings are clear that existing reading models do not describe this population. The implications are discussed in terms of instructional and curricular interventions. PMID:20179309
A stochastic analysis of terrain evaluation variables for path selection. [roving vehicle navigation
NASA Technical Reports Server (NTRS)
Donohue, J. G.; Shen, C. N.
1978-01-01
A stochastic analysis was performed on the variables associated with the characteristics of the terrain encountered by a roving system with an autonomous navigation system. A laser rangefinder is employed to detect terrain features at ranges up to 75 m. Analytic expressions and a numerical scheme were developed to calculate the variance of data on these four variables: (1) body clearance, (2) in-path slope, (3) tilt slope, and (4) wheel deviation. The variance is due to noise in the range data. It was found that the standard deviation of these terrain variables is large enough to warrant the use of a safety margin to aid the roving vehicle in avoiding high risk areas.
Hurd, Noelle M; Stoddard, Sarah A; Zimmerman, Marc A
2012-01-01
This study explored how neighborhood characteristics may relate to African American adolescents’ internalizing symptoms via adolescents’ social support and perceptions of neighborhood cohesion. Participants included 571 urban, African American adolescents (52% female; M age = 17.8). A multilevel path analysis testing both direct and indirect effects of neighborhood characteristics on adolescents’ mental health outcomes was conducted. Higher neighborhood poverty and unemployment rates predicted greater internalizing symptoms via lower cumulative social support and perceptions of neighborhood cohesion. In contrast, higher concentrations of African American and residentially stable residents in one’s neighborhood related to fewer internalizing symptoms among adolescent residents via greater cumulative social support and perceptions of neighborhood cohesion. Implications of these findings are discussed. PMID:23199188
[Monitoring and analysis of urban ozone using open path Fourier transform infrared spectrometry].
Li, Sheng; Gao, Min-guang; Zhang, Yu-jun; Liu, Wen-qing; Xu, Liang; Tong, Jing-jing; Cheng, Si-yang; Jin, Ling; Wei, Xiu-li; Wang, Ya-ping; Chen, Jun
2011-12-01
An ozone monitoring system was developed by the method of open path Fourier transform infrared (OP-FTIR) spectrometry based on our FTIR spectrometer. In order to improve measurement precision and detection limit, the quantitative analysis was completed to get ozone concentration by combining synthetic background spectrum method which uses information from HITRAN database and instrumental line shape, and nonlinear least squares (NLLSQ) method. The measurement methods for system detection limit were discussed and the result is 1.42 nmol x mol(-1) with sixteen times averages. The authors developed continuous monitoring experiments in the suburban area of Hefei. For the day and month measurement results, the authors analyzed their variations with the generation sources. The result has shown that this system is reliable and precise and can be used as a new device and method for national ozone monitoring.
The familial influence of loss and trauma on refugee mental health: a multilevel path analysis.
Nickerson, Angela; Bryant, Richard A; Brooks, Robert; Steel, Zachary; Silove, Derrick; Chen, Jack
2011-02-01
Although the impact of human rights violations on the mental health of refugees has been well documented, little is known about these effects at a family level. In this study the authors examined the relationships among loss, trauma, and mental health at the individual and family levels in resettled Mandaean refugees (N = 315). Trauma, loss, posttraumatic stress disorder, depression, complicated grief, and mental health-related quality of life were assessed. A multilevel path analysis revealed that loss and trauma significantly impacted on psychological outcomes at both the individual and family levels. Effect sizes ranged from .21 to .68 at the individual level, and .38 to .99 at the family level, highlighting the importance of the family when considering the psychological impact of refugee-related trauma. Copyright © 2011 International Society for Traumatic Stress Studies.
Analysis of non-rainy attenuation on earth-space path in Ota, Southwest Nigeria
NASA Astrophysics Data System (ADS)
Omotosho, T. V.; Akinwumi, S. A.; Usikalu, M. R.; Ometan, O. O.; Adewusi, M. O.; Abdullah, M.
2017-05-01
Propagation effects due to atmospheric gases and tropospheric scintillation requires accurate modelling in the design of satellite communication systems. The combination of the two attenuation phenomena was observed within the period of August 2014 to December 2015. The result of this paper presents the on-going observation and data analysis of non-rainy attenuation on earth-space path in Ota, Southwest Nigeria. Results of clear-sky attenuation vary between 0 dBm and 4.85 dBm in January and February 2015 respectively. While a value of 4.23 dBm and 4.75 dBm were observed in October 2014 and 2015 respectively. The results will be useful for satellite communication system design and will be submitted to ITU-R Study group 3 Databank.
A stochastic analysis of terrain evaluation variables for path selection. [roving vehicle navigation
NASA Technical Reports Server (NTRS)
Donohue, J. G.; Shen, C. N.
1978-01-01
A stochastic analysis was performed on the variables associated with the characteristics of the terrain encountered by a roving system with an autonomous navigation system. A laser rangefinder is employed to detect terrain features at ranges up to 75 m. Analytic expressions and a numerical scheme were developed to calculate the variance of data on these four variables: (1) body clearance, (2) in-path slope, (3) tilt slope, and (4) wheel deviation. The variance is due to noise in the range data. It was found that the standard deviation of these terrain variables is large enough to warrant the use of a safety margin to aid the roving vehicle in avoiding high risk areas.
Lockie, Stewart; Lyons, Kristen; Lawrence, Geoffrey; Grice, Janet
2004-10-01
Path analysis of attitudinal, motivational, demographic and behavioural factors influencing food choice among Australian consumers who had consumed at least some organic food in the preceding 12 months showed that concern with the naturalness of food and the sensory and emotional experience of eating were the major determinants of increasing levels of organic consumption. Increasing consumption was also related to other 'green consumption' behaviours such as recycling and to lower levels of concern with convenience in the purchase and preparation of food. Most of these factors were, in turn, strongly affected by gender and the level of responsibility taken by respondents for food provisioning within their households, a responsibility dominated by women. Education had a slightly negative effect on the levels of concern for sensory and emotional appeal due to lower levels of education among women. Income, age, political and ecological values and willingness to pay a premium for safe and environmentally friendly foods all had extremely minor effects.
Visualization and analysis of occlusion for human jaws using a "functionally generated path"
NASA Astrophysics Data System (ADS)
Myszkowski, Karol; Herder, Jens; Kunii, Tosiyasu L.; Ibusuki, Masumi
1996-03-01
Dynamic characteristics of occlusion during lower jaw motion are useful in the diagnosis of jaw articulation problems and in computer-aided design/ manufacture of teeth restorations. The Functionally Generated Path (FGP), produced as a surface which envelops the actual occlusal surface of the moving opponent jaw, can be used for compact representation of dynamic occlusal relations. In traditional dentistry FGP is recorded as a bite impression in a patient's mouth. We propose an efficient computerized technique for FGP reconstruction and validate it through implementation and testing. The distance maps between occlusal surfaces of jaws, calculated for multiple projection directions and accumulated for mandibular motion, provide information for FGP computation. Rasterizing graphics hardware is used for fast calculation of the distance maps. Real-world data are used: the scanned shape of teeth and the measured motion of the lower jaw. We show applications of FGP to analysis of the occlusion relations and occlusal surface design for restorations.
A path analysis of reading comprehension for adults with low literacy.
Mellard, Daryl F; Fall, Emily; Woods, Kari L
2010-01-01
Adult literacy interventions often rely on models of reading validated with children or adult populations with a broad range of reading abilities. Such models do not fully satisfy the need for intervention research and development for adults with low literacy. Thus, the authors hypothesized that a model representing the relationship between reading component skills would be predictive of reading comprehension for an adult population with low literacy and beneficial to adult literacy researchers. Using data from 174 adults participating in adult basic education and secondary education programs, the authors performed a path analysis of component skills' contribution to reading comprehension. The findings are clear that existing reading models do not describe this population. The implications are discussed in terms of instructional and curricular interventions.
NASA Astrophysics Data System (ADS)
Kim, Ba-Leum; Jung, Jin-Young; Oh, Il-Kwon
2017-06-01
In this study, we developed a modified transfer path analysis (MTPA) method to more accurately estimate the operational force of the main vibration source in a complicated system subjected to multiple vibration sources, base excitation and several disturbances. In the proposed method, transmissibility functions are adopted to compensate the disturbances due to base excitation or to reject transferred forces from other vibration sources. The MTPA method was verified numerically using a simple beam model and was practically applied to estimate vibration forces of a compressor in an outdoor air conditioner unit. Present results show that the MTPA method is feasible for predicting the pure operation forces of the compressor in an outdoor air conditioner unit regardless of the vibration sources due to a rotating fan and base excitations. The proposed MTPA method has very important advantages that it can be used to more accurately estimates the operational force of the main vibration source, properly rejecting other vibration sources and disturbances.
Peer and parental influences on adolescents' substance use: a path analysis.
Webster, R A; Hunter, M; Keats, J A
1994-04-01
Five hundred and seven 14-to-16-year-old students gave self-report responses to a substance use questionnaire. The questionnaire assessed adolescents' use, preferences, and norms and also their perceptions of their parents' and peers' use and norms in relation to alcohol, tobacco, and tea/coffee. Path analysis revealed that adolescents' internalization of parental and peer pressures is a stronger predictor of substance use than are direct effects. Internalized effects occur by means of preferences rather than norms, and peer pressure is predominantly through modeling behavior, whereas parental influence is through perceived normative standards. Peers' influence is stronger in relation to tobacco use, parental influence is stronger in relation to tea/coffee use, and both are equally important in relation to alcohol use. These findings are discussed in relation to preventive strategies.
Class start times, sleep, and academic performance in college: a path analysis.
Onyper, Serge V; Thacher, Pamela V; Gilbert, Jack W; Gradess, Samuel G
2012-04-01
Path analysis was used to examine the relationship between class start times, sleep, circadian preference, and academic performance in college-aged adults. Consistent with observations in middle and high school students, college students with later class start times slept longer, experienced less daytime sleepiness, and were less likely to miss class. Chronotype was an important moderator of sleep schedules and daytime functioning; those with morning preference went to bed and woke up earlier and functioned better throughout the day. The benefits of taking later classes did not extend to academic performance, however; grades were somewhat lower in students with predominantly late class schedules. Furthermore, students taking later classes were at greater risk for increased alcohol consumption, and among all the factors affecting academic performance, alcohol misuse exerted the strongest effect. Thus, these results indicate that later class start times in college, while allowing for more sleep, also increase the likelihood of alcohol misuse, ultimately impeding academic success.
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.
Vinicius, Lucio; Mumby, Hannah S
2013-05-01
The comparative analysis of animal growth still awaits full integration into life-history studies, partially due to the difficulty of defining a comparable measure of growth rate across species. Using growth data from 50 primate species, we introduce a modified "general growth model" and a dimensionless growth rate coefficient β that controls for size scaling and phylogenetic effects in the distribution of growth rates. Our results contradict the prevailing idea that slow growth characterizes primates as a group: the observed range of β values shows that not all primates grow slowly, with galago species exhibiting growth rates similar or above the mammalian average, while other strepsirrhines and most New World monkeys show limited reduction in growth rates. Low growth rate characterizes apes and some papionines. Phylogenetic regressions reveal associations between β and life-history variables, providing tests for theories of primate growth evolution. We also show that primate slow growth is an exclusively postnatal phenomenon. Our study exemplifies how the dimensionless approach promotes the integration of growth rate data into comparative life-history analysis, and demonstrates its potential applicability to other cases of adaptive diversification of animal growth patterns.
ERIC Educational Resources Information Center
Luk, HingKwan; Jacobs, Lucy C.
Two studies that compare the use of analysis of patterns in time (APT) (formerly non-metric temporal path analysis) and the linear models approach (LMA) are reported. In the first study, scores on the College Entrance Examination Board French Achievement Test (CEEBFAT), number of years of study of high school French (YHSF), and course achievement…
ERIC Educational Resources Information Center
McBee, Matthew
2010-01-01
This study focused on the analysis of a large-scale data set (N = 326,352) collected by the Georgia Department of Education using multilevel path analysis to model the probability that a student would be identified for participation in a gifted program. The model examined individual- and school-level factors that influence the probability that an…
ERIC Educational Resources Information Center
Luk, HingKwan; Jacobs, Lucy C.
Two studies that compare the use of analysis of patterns in time (APT) (formerly non-metric temporal path analysis) and the linear models approach (LMA) are reported. In the first study, scores on the College Entrance Examination Board French Achievement Test (CEEBFAT), number of years of study of high school French (YHSF), and course achievement…
NASA Astrophysics Data System (ADS)
Janse van Rensburg, E. J.
2010-08-01
In this paper the models of pulled Dyck paths in Janse van Rensburg (2010 J. Phys. A: Math. Theor. 43 215001) are generalized to pulled Motzkin path models. The generating functions of pulled Motzkin paths are determined in terms of series over trinomial coefficients and the elastic response of a Motzkin path pulled at its endpoint (see Orlandini and Whittington (2004 J. Phys. A: Math. Gen. 37 5305-14)) is shown to be R(f) = 0 for forces pushing the endpoint toward the adsorbing line and R(f) = f(1 + 2cosh f))/(2sinh f) → f as f → ∞, for forces pulling the path away from the X-axis. In addition, the elastic response of a Motzkin path pulled at its midpoint is shown to be R(f) = 0 for forces pushing the midpoint toward the adsorbing line and R(f) = f(1 + 2cosh (f/2))/sinh (f/2) → 2f as f → ∞, for forces pulling the path away from the X-axis. Formal combinatorial identities arising from pulled Motzkin path models are also presented. These identities are the generalization of combinatorial identities obtained in directed paths models to their natural trinomial counterparts.
NASA Astrophysics Data System (ADS)
Johnson, James; Conley, Catharine; Siegel, Bette
As systems, technologies, and plans for the human exploration of Mars and other destinations beyond low Earth orbit begin to coalesce, it is imperative that frequent and early consideration is given to how planetary protection practices and policy will be upheld. While the development of formal planetary protection requirements for future human space systems and operations may still be a few years from fruition, guidance to appropriately influence mission and system design will be needed soon to avoid costly design and operational changes. The path to constructing such requirements is a journey that espouses key systems engineering practices of understanding shared goals, objectives and concerns, identifying key stakeholders, and iterating a draft requirement set to gain community consensus. This paper traces through each of these practices, beginning with a literary analysis of nearly three decades of publications addressing planetary protection concerns with respect to human exploration. Key goals, objectives and concerns, particularly with respect to notional requirements, required studies and research, and technology development needs have been compiled and categorized to provide a current ‘state of knowledge’. This information, combined with the identification of key stakeholders in upholding planetary protection concerns for human missions, has yielded a draft requirement set that might feed future iteration among space system designers, exploration scientists, and the mission operations community. Combining the information collected with a proposed forward path will hopefully yield a mutually agreeable set of timely, verifiable, and practical requirements for human space exploration that will uphold international commitment to planetary protection. Keywords: planetary protection, human spaceflight requirements, human space exploration, human space operations, systems engineering, literature analysis
Intimate partner violence in the eastern part of Iran: a path analysis of risk factors.
Moghaddam Hosseini, Vahideh; Asadi, Zahra Sadat; Akaberi, Arash; Hashemian, Masoumeh
2013-08-01
Intimate partner violence against women is a widespread phenomenon that is the cause of many deleterious health and social consequences. This study examines the impact of some risk factors on partner violence in the eastern region of Iran, using path analysis. The study used a population-based cross sectional study design. In this study, 251 married women who were referred to the health centers were selected through a proportionally stratified and randomized sampling method. Domestic violence was measured using Conflict Tactics Scale and the socio-demographic variable was assessed by a self-report questionnaire. Bayesian Structural Equation Modeling was used for evaluating the overall path analysis and the direct and indirect p-value was estimated by Bootstrap method. AMOS and SPSS software were used to analyze data. The prevalence of overall violence was 78.1%, with 37.8% and 0.8% of women reporting minor and severe violence, respectively, and 39.8% reporting both severe and minor forms of violence. Psychological violence was the most common type of violence reported (66.5%). The model showed that husbands' drug abuse and women's higher level of education compared to their husbands were the first and second most important factors that significantly and directly influenced the violence. The women's attitude, however, had the least effect on the violence. The findings indicated that higher educated women and women with addicted husbands were more likely to experience violence. Treating the drug abuse disorders, especially mental disorders, using behavioral couple's therapy, as well as modifying certain traditional and cultural biases against women's empowerment are suggested.
Tansey, Timothy N; Iwanaga, Kanako; Bezyak, Jill; Ditchman, Nicole
2017-05-04
Individuals with disabilities are more likely to live in poverty, have more health issues, and be less likely to be employed than their same-aged peers. Although these issues may be attenuated by vocational rehabilitation services, amotivation and ambivalence to employment can limit the readiness of persons with disabilities to engage in these services. Drawing on self-efficacy, self-determination, and stages of change theories, the purpose of this study was to develop and test an integrated self-determined work motivation model for people with disabilities. Participants included 277 people with disabilities recruited through vocational rehabilitation agencies across 8 states. Path analysis was used to evaluate the contribution of functional disability, self-determination, and social efficacy variables in a hypothesized integrated self-determined work motivation model. Model estimations used maximum likelihood estimation and model-data fit was examined using several goodness-of-fit indices. The initial path analysis indicated a less than optimal fit between the model and the observed data. Post hoc model modifications were conducted based on examination of the critical ratios and modification indices and theoretical consideration. The respecified integrated self-determined work motivation model fit the data very well, χ2/df = 1.88, CFI = .99, and RMSEA = 0.056. The R2 for the endogenous variables in the model ranged from .19 to .54. Findings from this study support the integrated self-determined work motivation model in vocational rehabilitation as a useful framework for understanding the relationship among functioning levels, self-determination and self-efficacy factors, vocational rehabilitation engagement, and readiness for employment. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Honjo, Kaori; Tsutsumi, Akizumi; Kawachi, Ichiro; Kawakami, Norito
2006-01-01
Despite the overall decline in cigarette smoking prevalence in the US, social class inequalities in smoking are likely to persist, or even to widen. One possible reason for the increasing gap in smoking prevalence across social class could be our lack of understanding of causal mechanisms: in other words, what accounts for the social gradient in smoking behavior? In this paper, we examine the mechanisms behind social gradients related to smoking cessation by use of path analysis techniques. The data come from a 3-year follow-up telephone survey of a cohort of US adults. The sample for the present analysis was drawn from the 481 respondents who reported being smokers and employed at baseline and who completed the follow-up interview. We examined two social class indicators, educational attainment and household income, in relation to smoking cessation. We tested the potential mediating effects of the following variables: differential use of resources for smoking cessation (e.g., booklet, pamphlet, quit line, nicotine replacement therapy and smoking cessation program), differential environments in terms of smoking at worksite and home, and differences in peer smoking. Our path analyses suggest that smokers from high social class are likely to use effective resources for smoking cessation and have restrictive home environment in terms of smoking, which leads to a relatively higher smoking cessation rate compared to those from low social class. The results of this study suggest that interventions should target resources for smoking cessation and home environments in terms of smoking to reduce socio-economic disparities in smoking cessation.
Rigdon, J. Brian; Smith, Marcus Daniel; Mulder, Samuel A
2014-01-07
PathFinder is a graph search program, traversing a directed cyclic graph to find pathways between labeled nodes. Searches for paths through ordered sequences of labels are termed signatures. Determining the presence of signatures within one or more graphs is the primary function of Path Finder. Path Finder can work in either batch mode or interactively with an analyst. Results are limited to Path Finder whether or not a given signature is present in the graph(s).
[Optical Path Difference Analysis and Simulation of Four Typical Rotary Type Interferometer].
Feng, Ming-chun; Liu, Wen-qing; Xu, Liang; Gao, Min-guang; Wei, Xiu-li; Tong, Jing-jing; Li, Xiang-xian
2015-11-01
The four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type optical path difference of the interferometer are simulated based on the optical path difference formula. The rotation velcocity of the four kinds of interferometers is also simulated. By simulation and contrast of the optical path difference, the relationship is intuitively reflect by figure between the optical path difference and the rotation angle. The scope of the rotation angle is discussed within 3% of the velocity errors. It is the very good reference significance to study the structure and properties of the interferometer by analyzing and simulating the optical path difference discussed in the paper.
Delgado, J; Liao, J C
1992-01-01
The methodology previously developed for determining the Flux Control Coefficients [Delgado & Liao (1992) Biochem. J. 282, 919-927] is extended to the calculation of metabolite Concentration Control Coefficients. It is shown that the transient metabolite concentrations are related by a few algebraic equations, attributed to mass balance, stoichiometric constraints, quasi-equilibrium or quasi-steady states, and kinetic regulations. The coefficients in these relations can be estimated using linear regression, and can be used to calculate the Control Coefficients. The theoretical basis and two examples are discussed. Although the methodology is derived based on the linear approximation of enzyme kinetics, it yields reasonably good estimates of the Control Coefficients for systems with non-linear kinetics. PMID:1497632
Analysis of Manning’s and Drag Coefficients for Flexible Submerged Vegetation
NASA Astrophysics Data System (ADS)
Yusof, Khamaruzaman Wan; Mujahid Muhammad, Muhammad; Mustafa, Muhammad Raza Ul; Azazi Zakaria, Nor; Gahani, Aminuddin Ab.
2017-06-01
Accurate determination of flow resistance is of great significance in modelling of open channels that will convey water efficiently. Although, resistance or drag induced by vegetation have been systematically studied for several decades, estimating of the resistance remain as a challenge. This is because most of previous studies use artificial vegetation to investigate flow - vegetation interactions. To overcome this, the present study evaluates the vegetation resistance in terms of Manning’s roughness coefficient and drag coefficient using a natural flexible vegetation (cow grass) under submerged condition. From the experimental result obtained, it was observed that the Manning’s and drag coefficients decreased with the increasing in average velocity. Also, graphical relationship between Manning’s coefficient, n and drag coefficient, CD has been developed with R2 = 0.9465, which indicate that there exist a strong correlation between n and CD, and one can use the proposed graphical model to predict the n - values corresponding to the CD - values.
Worry, Worry Attacks, and PTSD among Cambodian Refugees: A Path Analysis Investigation
Hinton, Devon E.; Nickerson, Angela; Bryant, Richard A.
2011-01-01
Among traumatized Cambodian refugees, this article investigates worry (e.g., the types of current life concerns) and how worry worsens posttraumatic stress disorder (PTSD). To explore how worry worsens PTSD, we examine a path model of worry to see whether certain key variables (e.g., worry-induced somatic arousal and worry-induced trauma recall) mediate the relationship between worry and PTSD. Survey data were collected from March 2010 until May 2010 in a convenience sample of 201 adult Cambodian refugees attending a psychiatric clinic in Massachusetts, USA. We found that worry was common in this group (65%), that worry was often about current life concerns (e.g., lacking financial resources, children not attending school, health concerns, concerns about relatives in Cambodia), and that worry often induced panic attacks: in the entire sample, 41% (83/201) of the patients had “worry attacks” (i.e., worry episodes that resulted in a panic episode) in the last month. “Worry attacks” were highly associated with PTSD presence. In the entire sample, generalized anxiety disorder was also very prevalent, and was also highly associated with PTSD. Path analysis revealed that the effect of worry on PTSD severity was mediated by worry-induced somatic arousal, worry-induced catastrophic cognitions, worry-induced trauma recall, inability to stop worry, and irritability. The final model accounted for 75% of the variance in PTSD severity among patients with worry. The public health and treatment implications of the study’s findings that worry may have a potent impact on PTSD severity in severely traumatized populations are discussed: worry and daily concerns are key areas of intervention for these worry-hypersensitive (and hence daily-stressor-hypersensitive) populations. PMID:21663803
Leak-Path Factor Analysis for the Nuclear Materials Storage Facility
Shaffer, C.; Leonard, M.
1999-06-13
Leak-path factors (LPFs) were calculated for the Nuclear Materials Storage Facility (NMSF) located in the Plutonium Facility, Building 41 at the Los Alamos National Laboratory Technical Area 55. In the unlikely event of an accidental fire powerful enough to fail a container holding actinides, the subsequent release of oxides, modeled as PuO{sub 2} aerosols, from the facility and into the surrounding environment was predicted. A 1-h nondestructive assay (NDA) laboratory fire accident was simulated with the MELCOR severe accident analysis code. Fire-driven air movement along with wind-driven air infiltration transported a portion of these actinides from the building. This fraction is referred to as the leak-path factor. The potential effect of smoke aerosol on the transport of the actinides was investigated to verify the validity of neglecting the smoke as conservative. The input model for the NMSF consisted of a system of control volumes, flow pathways, and surfaces sufficient to model the thermal-hydraulic conditions within the facility and the aerosol transport data necessary to simulate the transport of PuO{sub 2} particles. The thermal-hydraulic, heat-transfer, and aerosol-transport models are solved simultaneously with data being exchanged between models. A MELCOR input model was designed such that it would reproduce the salient features of the fire per the corresponding CFAST calculation. Air infiltration into and out of the facility would be affected strongly by wind-driven differential pressures across the building. Therefore, differential pressures were applied to each side of the building according to guidance found in the ASHRAE handbook using a standard-velocity head equation with a leading multiplier to account for the orientation of the wind with the building. The model for the transport of aerosols considered all applicable transport processes, but the deposition within the building clearly was dominated by gravitational settling.
Worry, worry attacks, and PTSD among Cambodian refugees: a path analysis investigation.
Hinton, Devon E; Nickerson, Angela; Bryant, Richard A
2011-06-01
Among traumatized Cambodian refugees, this article investigates worry (e.g., the types of current life concerns) and how worry worsens posttraumatic stress disorder (PTSD). To explore how worry worsens PTSD, we examine a path model of worry to see whether certain key variables (e.g., worry-induced somatic arousal and worry-induced trauma recall) mediate the relationship between worry and PTSD. Survey data were collected from March 2010 until May 2010 in a convenience sample of 201 adult Cambodian refugees attending a psychiatric clinic in Massachusetts, USA. We found that worry was common in this group (65%), that worry was often about current life concerns (e.g., lacking financial resources, children not attending school, health concerns, concerns about relatives in Cambodia), and that worry often induced panic attacks: in the entire sample, 41% (83/201) of the patients had "worry attacks" (i.e., worry episodes that resulted in a panic episode) in the last month. "Worry attacks" were highly associated with PTSD presence. In the entire sample, generalized anxiety disorder was also very prevalent, and was also highly associated with PTSD. Path analysis revealed that the effect of worry on PTSD severity was mediated by worry-induced somatic arousal, worry-induced catastrophic cognitions, worry-induced trauma recall, inability to stop worry, and irritability. The final model accounted for 75% of the variance in PTSD severity among patients with worry. The public health and treatment implications of the study's findings that worry may have a potent impact on PTSD severity in severely traumatized populations are discussed: worry and daily concerns are key areas of intervention for these worry-hypersensitive (and hence daily-stressor-hypersensitive) populations.
Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation.
Lawrence, Michael A; Leib, Daniel J; Ostrowski, Stephanie J; Carlson, Lara A
2017-05-01
Lawrence, MA, Leib, DJ, Ostrowski, SJ, and Carlson, LA. Nonlinear analysis of an unstable bench press bar path and muscle activation. J Strength Cond Res 31(5): 1206-1211, 2017-Unstable resistance exercises are typically performed to improve the ability of stabilizing muscles to maintain joint integrity under a load. The purpose of this study was to examine the effects of an unstable load (as provided by a flexible barbell and a load suspended by elastic bands) on the bar path, the primary musculature, and stabilizing musculature while bench pressing using nonlinear analyses. Fifteen resistance-trained men (age 24.2 ± 2.7 years, mass 84.1 ± 12.0 kg, height 1.77 ± 0.05 m, 9.9 ± 3.4 years of lifting experience, and bench press 1 repetition maximum (RM) 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (total load 75% 1RM) and unstable (total load 60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and bar stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). During the unstable condition, the bar moved in more ways and was less predictable in the mediolateral and anteroposterior directions. However, the muscle activation patterns of all muscles were more constrained with the unstable barbell. These findings suggest that the unstable condition was more challenging to control, but subjects controlled the instability by contracting their muscles in a more stable pattern or "staying tight" throughout the exercise.
WFC3/UVIS External CTE Monitor: 2016 Updates on Coefficients and Analysis Pipeline
NASA Astrophysics Data System (ADS)
Gosmeyer, C. M.; Baggett, S.
2017-03-01
The evolution of the charge transfer efficiency (CTE) of Hubbleâs WFC3/UVIS detector has been monitored since 2009, using observations of star clusters NGC 104 and NGC 6791. We present here results from an updated analysis pipeline with an improved cross-identification of sources and a new capability to study CTE loss mitigation by use of flash levels 6 - 116 e-/pix. We measure flux loss due to CTE degradation as a function of source brightness, observation date, background level, and vertical distance from the readout amplifier with a 2nd degree polynomial, whose coefficients are provided to allow observers to estimate flux corrections for their point-source photometry. Current flux losses for images with the recommended minimum 12 e-/pix background are 5 - 15%, depending on source brightness. These losses are further reduced via use of the CTE-corrected images now available from the Mikulski Archive for Space Telescopes. Within its overall growth, there appears to be a flattening in the CTE degradation rate that may be correlated with the Solar cycle maximum. The data reported here span from October 2009 to August 2016 and were calibrated with calwf3 v3.3.
NASA Astrophysics Data System (ADS)
Yamaikina, Irene V.; Furmanchuk, Dmitryi A.
1998-06-01
Method of erythrocyte sedimentation rate (ESR) measurement is non-specific one. The ESR are tightly correlated to increase or decrease of aggregation coefficient (N). The variations of N could happen due to two main reasons: either changes in concentration of plasma proteins (first of all of fibrinogen) or changes of erythrocyte membrane characteristics (surface charge, transmembrane potential). The cross-method of ESR analysis has been proposed, using blood samples from patient and healthy donor of the same ABO blood groups and Rh-factors. The hematocrit (Ho)-ESR dependencies were measured in four variants: (1) patient's erythrocytes in patient's plasma; (2) patient's erythrocytes in donor's plasma; (3) donor's erythrocytes in donor's plasma; (4) donor's erythrocytes in patient's plasma. On presenting the ESR data for more than 100 patients with different bone marrow disorders after chemotherapy in the coordinates Ho-ESR three conventional zones could be marked out: high-ESR zone, medium zone and zone of low level of Ho. Proposed cross-method allows to estimate which of the two aforementioned reasons results in ESR variation. Some patients revealed not only changed fibrinogen level but additional changes in membrane affinity to fibrinogen. The modificated ESR cross-method opens us some new capacities in medical diagnostics.
Ray propagation path analysis of acousto-ultrasonic signals in composites
NASA Technical Reports Server (NTRS)
Kautz, Harold E.
1987-01-01
The most important result was the demonstration that acousto-ultrasonic (AU) energy introduced into a laminated graphite/resin propagates by two modes through the structure. The first mode, along the graphite fibers, is the faster. The second mode, through the resin matrix, besides being slower is also more strongly attenuated at the higher frequencies. This demonstration was accomplished by analyzing the time and frequency domain of the composite AU signal and comparing them to the same for a neat resin specimen of the same chemistry and geometry as the composite matrix. Analysis of the fine structure of AU spectra was accomplished by various geometrical strategies. It was shown that the multitude of narrow peaks associated with AU spectra are the effect of the many pulse arrivals in the signal. The shape and distribution of the peaks is mainly determined by the condition of nonnormal reflections of ray paths. A cepstrum analysis was employed which can be useful in detecting characteristic times. Analysis of propagation modes can be accomplished while ignoring the fine structure.
Comparative Analysis of Control Coefficients on the Performance of CNTFET Under Different Parameters
NASA Astrophysics Data System (ADS)
Imam, Safayat-Al; Kalam, Nasheen; Abdullah, Sharmin
2016-02-01
This paper deals with the performance of both gate and drain control coefficients to analyze the behavior of carbon nanotube field effect transistors (CNTFETs) under ballistic conditions and based on the change of different parameter value, such as oxide thickness of structure and temperature variation. A thorough study of both gate and drain control coefficient effects on the performance of CNTFETs has been conducted under different temperature and oxide layers and the output of the device has been analyzed through different parameters. Higher values of control coefficient help to attain larger transconductance by the increasing temperatures. For a fixed value of control coefficient, 4nm thickness of oxide has a transconductance of ˜ 4.5 × 10-5 S/m. Smaller oxide layer thickness has higher slope of increment in transconductance value. ON-state current to leakage current ratio shows a steady state response toward increment of gate control coefficient. Also, increment of oxide thickness has an adverse effect on current ratio, while a linear decay of current ratio is observed with the increased value of drain controlled one. Drain-induced battery lowering (DIBL) effect decreases with the value of gate control one and increases with the drain control coefficient. In this way, the optimum value for both the control coefficients has to be considered in order to perform well.
NASA Technical Reports Server (NTRS)
Brooks, Cuyler W., Jr.; Harris, Charles D.; Harvey, William D.
1991-01-01
A swept supercritical wing incorporating laminar flow control at transonic flow conditions was designed and tested. The definition of an experimental suction coefficient and a derivation of the compressible and incompressible formulas for the computation of the coefficient from measurable quantities is presented. The suction flow coefficient in the highest velocity nozzles is shown to be overpredicted by as much as 12 percent through the use of an incompressible formula. However, the overprediction on the computed value of suction drag when some of the suction nozzles were operating in the compressible flow regime is evaluated and found to be at most 6 percent at design conditions.
Vassar, Matt; Bradley, Greg
2012-10-01
The purpose of this study was to use a meta-analytic method known as reliability generalization to investigate the score reliability for a popular depression measure: The Reynolds Adolescent Depression Scale. We used the technique to provide an aggregate estimate of coefficient alpha across empirical studies that have employed the measure over time and across populations. Furthermore, we identified sample and demographic characteristics associated with variance in coefficient alpha. We discuss conditions associated with variability in coefficient alpha and alert researchers and practitioners to appropriate uses of the scale based on common reliability benchmarks.
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.
NASA Astrophysics Data System (ADS)
Mockler, E. M.; O'Loughlin, F.; Bruen, M. P.
2013-12-01
Conceptual rainfall runoff (CRR) models aim to capture the dominant hydrological processes in a catchment in order to predict the flows in a river. Most flood forecasting models focus on predicting total outflows from a catchment and often perform well without the correct distribution between individual pathways. However, modelling of water flow paths within a catchment, rather than its overall response, is specifically needed to investigate the physical and chemical transport of matter through the various elements of the hydrological cycle. Focus is increasingly turning to accurately quantifying the internal movement of water within these models to investigate if the simulated processes contributing to the total flows are realistic in the expectation of generating more robust models. Parameter regionalisation is required if such models are to be widely used, particularly in ungauged catchments. However, most regionalisation studies to date have typically consisted of calibrations and correlations of parameters with catchment characteristics, or some variations of this. In order for a priori parameter estimation in this manner to be possible, a model must be parametrically parsimonious while still capturing the dominant processes of the catchment. The presence of parameter interactions within most CRR model structures can make parameter prediction in ungauged basins very difficult, as the functional role of the parameter within the model may not be uniquely identifiable. We use a variance based sensitivity analysis method to investigate parameter sensitivities and interactions in the global parameter space of three CRR models, simulating a set of 30 Irish catchments within a variety of hydrological settings over a 16 year period. The exploration of sensitivities of internal flow path partitioning was a specific focus and correlations between catchment characteristics and parameter sensitivities were also investigated to assist in evaluating model performances
On load paths and load bearing topology from finite element analysis
NASA Astrophysics Data System (ADS)
Kelly, D.; Reidsema, C.; Lee, M.
2010-06-01
Load paths can be mapped from vector plots of 'pointing stress vectors'. They define a path along which a component of load remains constant as it traverses the solution domain. In this paper the theory for the paths is first defined. Properties of the plots that enable a designer to interpret the structural behavior from the contours are then identified. Because stress is a second order tensor defined on an orthogonal set of axes, the vector plots define separate paths for load transfer in each direction of the set of axes. An algorithm is therefore presented that combines the vectors to define a topology to carry the loads. The algorithm is shown to straighten the paths reducing bending moments and removing stress concentration. Application to a bolted joint, a racing car body and a yacht hull demonstrate the usefulness of the plots.
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)
ERIC Educational Resources Information Center
Middleton, James A.; Leavy, Aisling; Leader, Lars
2013-01-01
This study investigated the relationship among critical motivational variables and mathematics achievement as middle grades students engaged in a reform-oriented curriculum, "Mathematics in Context." We tested 327 students in fifth, sixth, and seventh grade before and after two years of implementation. We performed a path analysis with…
ERIC Educational Resources Information Center
Tonyan, Holli A.; Nuttall, Joce
2014-01-01
Family day care or childminding involves a particularly transient workforce. This paper introduces Eco(logical)-Cultural Theory (ECT) to examine the cultural organisation of childminding and presents an ECT analysis of pilot survey results: asking minders about their daily routines and their career paths. Reasons for becoming a minder and…
ERIC Educational Resources Information Center
Tonyan, Holli A.; Nuttall, Joce
2014-01-01
Family day care or childminding involves a particularly transient workforce. This paper introduces Eco(logical)-Cultural Theory (ECT) to examine the cultural organisation of childminding and presents an ECT analysis of pilot survey results: asking minders about their daily routines and their career paths. Reasons for becoming a minder and…
Pereira, Jose Antonio Sousa; Rosado, Elsa; Bali, Maria; Metens, Thierry; Chao, Shih-Li
2015-10-01
To explore the role of histogram analysis of apparent diffusion coefficient (ADC) MRI maps based on entire tumor volume data in determining pancreatic neuroendocrine tumor (PNT) grade. Retrospective evaluation of 22 patients with PNTs included low-grade (G1; n = 15), intermediate-grade (G2; n = 4), and high-grade (G3; n = 3) tumors. Regions of interest containing the lesion were drawn on every section of the ADC map containing the tumor and summated to obtain histograms for entire tumor volume. Calculated histographic parameters included mean ADC (mADC), 5th percentile ADC, 10th percentile ADC, 25th percentile ADC, 50th percentile ADC, 75th percentile ADC (ADC75), 90th percentile ADC (ADC90) and 95th percentile ADC (ADC95), skewness and kurtosis. Histogram parameters were correlated with tumor grade by repeated measures analysis of variance with Tukey-Kramer post hoc comparisons. The mADC, ADC75, ADC90, and ADC95 were significantly higher in G1 tumors (1283 ± 267; 1404 ± 300; 1495 ± 318; 1562 ± 347 × 10(-6) mm(2)/s) compared to G2 (892 ± 390; 952 ± 381; 1036 ± 384; 1072 ± 374 × 10(-6) mm(2)/s) and to G3 tumors (733 ± 225; 864 ± 284; 1008 ± 288; 1152 ± 192 × 10(-6) mm(2)/s) (p value <0.05). Skewness and kurtosis were significantly different between G1 (0.041 ± 0.466; 2.802 ± 0.679) and G3 (1.01 ± 1.140; 5.963 ± 4.008) tumors (p value <0.05). Tumor volume (mL) was significantly higher on G3 (55 ± 15.7) compared to G1 (1.9 ± 2.7) and G2 (4.5 ± 3.6) tumors (p value <0.05). In this small sample size, we did not detect statistically significant parameters between G2 (n = 4) and G3 (n = 3) tumors. Histographic analysis of ADC maps on the basis of the entire tumor volume can be useful in differentiating histologic grades of PNTs.
Røysland, Kjetil; Gran, Jon Michael; Ledergerber, Bruno; von Wyl, Viktor; Young, James; Aalen, Odd O
2011-10-30
When applying survival analysis, such as Cox regression, to data from major clinical trials or other studies, often only baseline covariates are used. This is typically the case even if updated covariates are available throughout the observation period, which leaves large amounts of information unused. The main reason for this is that such time-dependent covariates often are internal to the disease process, as they are influenced by treatment, and therefore lead to confounded estimates of the treatment effect. There are, however, methods to exploit such covariate information in a useful way. We study the method of dynamic path analysis applied to data from the Swiss HIV Cohort Study. To adjust for time-dependent confounding between treatment and the outcome 'AIDS or death', we carried out the analysis on a sequence of mimicked randomized trials constructed from the original cohort data. To analyze these trials together, regular dynamic path analysis is extended to a composite analysis of weighted dynamic path models. Results using a simple path model, with one indirect effect mediated through current HIV-1 RNA level, show that most or all of the total effect go through HIV-1 RNA for the first 4 years. A similar model, but with CD4 level as mediating variable, shows a weaker indirect effect, but the results are in the same direction. There are many reasons to be cautious when drawing conclusions from estimates of direct and indirect effects. Dynamic path analysis is however a useful tool to explore underlying processes, which are ignored in regular analyses. Copyright © 2011 John Wiley & Sons, Ltd.
NASA Astrophysics Data System (ADS)
Yan, Baozhu; Liu, Wenguang; Zhou, Qiong; Du, Shaojun; Yang, Yi
2017-06-01
In order to measure the absorption coefficient and performance degradation characteristics of optical components which used in high power laser system, an intra-cavity device was established based on a discharge-drived CW chemical laser. Two pieces of 45 degree reflecting mirrors were tested. Each mirror was tested for more than twenty times, and high power laser irradiation on the testing mirrors lasted 100 seconds continuously in each test. The dependence of absorption coefficients on irradiation times was acquired. The testing results of both reflecting mirrors showed that, the differences between the experimental absorption coefficients and their fitting curve were up to 30.7% and 21.6% respectively, and the differences were independent of irradiation condition, such as irradiation energy, irradiation power and beam crosssectional area. The uncertainty of absorption coefficient was composed of two parts. For one thing, the uncertainty of the direct measurement results, such as the temperature rise of optical components, can cause the uncertainty of absorption coefficients. This part of uncertainty was about 11.3%. For another, the resonant cavity need to be adjusted again when other optical components were replaced, which lead to the change of the incident angle of the optical components to be measured. A typical film system of 24 layers (12 pairs) was calculated by Thin Film Design Software called TFCalc, which showed the absorption coefficients increased with the increase of incident angle. When the angle of incidence was 0.5 degree from the design value, there would be -60 71ppm difference of absorption coefficient from the original one, and the uncertainty was 14.5%. When there was a deviation of 1 degree, the difference of absorption coefficient and the uncertainty were -112 155ppm and 31.7% respectively. This results showed that, the deviation of incident angle was between 0.5 1 degree in the test. In order to reduce the testing uncertainty of absorption
Influences of system uncertainties on the numerical transfer path analysis of engine systems
NASA Astrophysics Data System (ADS)
Acri, A.; Nijman, E.; Acri, A.; Offner, G.
2017-10-01
Practical mechanical systems operate with some degree of uncertainty. In numerical models uncertainties can result from poorly known or variable parameters, from geometrical approximation, from discretization or numerical errors, from uncertain inputs or from rapidly changing forcing that can be best described in a stochastic framework. Recently, random matrix theory was introduced to take parameter uncertainties into account in numerical modeling problems. In particular in this paper, Wishart random matrix theory is applied on a multi-body dynamic system to generate random variations of the properties of system components. Multi-body dynamics is a powerful numerical tool largely implemented during the design of new engines. In this paper the influence of model parameter variability on the results obtained from the multi-body simulation of engine dynamics is investigated. The aim is to define a methodology to properly assess and rank system sources when dealing with uncertainties. Particular attention is paid to the influence of these uncertainties on the analysis and the assessment of the different engine vibration sources. Examples of the effects of different levels of uncertainties are illustrated by means of examples using a representative numerical powertrain model. A numerical transfer path analysis, based on system dynamic substructuring, is used to derive and assess the internal engine vibration sources. The results obtained from this analysis are used to derive correlations between parameter uncertainties and statistical distribution of results. The derived statistical information can be used to advance the knowledge of the multi-body analysis and the assessment of system sources when uncertainties in model parameters are considered.
NASA Technical Reports Server (NTRS)
Shealy, D. L.; Chao, S.
1984-01-01
A ray tracing analysis was performed for several configurations for the inner channel of the dual path X-ray telescope, which is proposed to use the second mirror of the Stanford/MSFC Wolter-Schwarzchild telescope and a normal incident layered synthetic microstructure (LSM) mirror to form a secondary image near the front of the telescope. The LSM mirror shapes considered were spherical, ellipsoid, hyperboloid, and constant optical path length (OPL) aspheric. Only the constant OPL case gave good axial resolution. All cases had poor off axis resolution as judged by the RMS blur circle radius.
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
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.
NASA Astrophysics Data System (ADS)
Yu, Shao-De; Wu, Shi-Bin; Wang, Hao-Yu; Wei, Xin-Hua; Chen, Xin; Pan, Wan-Long; Hu, Jiani; Xie, Yao-Qin
2015-12-01
Similarity coefficient mapping (SCM) aims to improve the morphological evaluation of weighted magnetic resonance imaging However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM? The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multi-echo . Generated maps were investigated from signal-to-noise ratio (SNR) and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation. Project supported in part by the National High Technology Research and Development Program of China (Grant Nos. 2015AA043203 and 2012AA02A604), the National Natural Science Foundation of China (Grant Nos. 81171402, 61471349, and 81501463), the Innovative Research Team Program of Guangdong Province, China (Grant No. 2011S013), the Science and Technological Program for Higher Education, Science and Research, and Health Care Institutions of Guangdong Province, China (Grant No. 2011108101001), the Natural Science Foundation of Guangdong Province, China (Grant No. 2014A030310360), the Fundamental Research Program of Shenzhen City, China (Grant No. JCYJ20140417113430639), and Beijing Center for Mathematics and Information Interdisciplinary Sciences, China.
Federal Guidance Report No.13 (FGR 13) provides cancer risk coefficients for modes of environmental exposure to each of more than 800 radionuclides (EPA 1999), including inhalation of airborne activity and ingestion of activity in food or drinking water.
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
General framework for transfer path analysis: History, theory and classification of techniques
NASA Astrophysics Data System (ADS)
van der Seijs, Maarten V.; de Klerk, Dennis; Rixen, Daniel J.
2016-02-01
Transfer Path Analysis (TPA) designates the family of test-based methodologies to study the transmission of mechanical vibrations. Since the first adaptation of electric network analogies in the field of mechanical engineering a century ago, a multitude of TPA methods have emerged and found their way into industrial development processes. Nowadays the TPA paradigm is largely commercialised into out-of-the-box testing products, making it difficult to articulate the differences and underlying concepts that are paramount to understanding the vibration transmission problem. The aim of this paper is to derive and review a wide repertoire of TPA techniques from their conceptual basics, liberating them from their typical field of application. A selection of historical references is provided to align methodological developments with particular milestones in science. Eleven variants of TPA are derived from a unified framework and classified into three categories, namely classical, component-based and transmissibility-based TPA. Current challenges and practical aspects are discussed and reference is made to related fields of research.
A multilevel path analysis of contact frequency between social network members
NASA Astrophysics Data System (ADS)
van den Berg, Pauline; Arentze, Theo; Timmermans, Harry
2012-04-01
Recently, there has been an increasing interest in the role of social networks in spatial-choice and travel behavior. It has been acknowledged that social activities and the travel for these activities can emerge from individuals' social networks and that social activities are responsible for an important portion of travel demand. The influence of information and communication technologies (ICT's) is also important in this respect. The purpose of the paper is to examine the effects of characteristics of egos and ego-alter relationships on the frequency of social interaction by different communication modes, using multilevel path analysis. The analyses are based on social network data collected in 2008 in the Eindhoven region in the Netherlands among 116 respondents. The results indicate a complementary relationship between contact frequencies by different modes. The contact frequencies of the different modes, especially face-to-face and telephone, can also be largely explained by the ego's personal characteristics and the type of relationship and the distance between ego and alter.
Nickerson, Angela; Bryant, Richard A; Brooks, Robert; Steel, Zachary; Silove, Derrick
2009-01-01
The Mandaeans are a small religious community originating from Iraq and Iran who are facing the possibility of cultural extinction within the next few generations. This study aimed to examine the relationships between life experiences, psychopathology and fear of cultural extinction in Mandaean refugees. A survey was conducted of 315 adult Iraqi Mandaean refugees living in Australia. Past traumatic experiences and current resettlement difficulties were assessed. Mental health outcomes were also examined, including measures of posttraumatic stress disorder (PTSD) and depression. Fear of cultural extinction was measured by items developed in consultation with the Mandaean community. A path analysis was employed to investigate the relationship between trauma, living difficulties, PTSD, depression, and fear of cultural extinction. Results indicated that trauma and living difficulties impacted indirectly on fear of cultural extinction, while PTSD (and not depression) directly predicted levels of anxiety about the Mandaean culture ceasing to exist. The current findings indicate that past trauma and symptoms of posttraumatic stress contribute to fear of cultural extinction. Exposure to human rights violations enacted on the basis of religion has significant mental health consequences that extend beyond PTSD. The relationship between perception of threat, PTSD, and fear of cultural extinction is considered in the context of cognitive models of traumatic stress. Government immigration policy must prioritize the reunification of small, endangered groups to sustain cultural traditions. Treatment interventions implemented with cultural groups facing extinction should take into consideration anxiety about loss of culture.
The Longitudinal Process of Early Parent Involvement on Student Achievement: A Path Analysis
Hayakawa, Momoko; Englund, Michelle M.; Warner-Richter, Mallory N.; Reynolds, Arthur J
2016-01-01
This longitudinal study investigated the process whereby early parent involvement in preschool effects student achievement from kindergarten through 6th grade. Participants were 1,539 low-income, mainly African American children and their mothers, in the Chicago Longitudinal Study. Program children (N = 989) received one or two years of the Child-Parent Center (CPC) program – a preschool intervention that strongly promoted parents' development of parent involvement skills within the school and at home. Children from similar backgrounds who did not attend the CPC, but participated in available local resources (e.g. day care), were obtained as a comparison group (N = 550). Path analysis revealed an interactive process between parent involvement, academic achievement, and children's motivation. Early parent involvement directly influenced kindergarten achievement, which in turn influenced first grade student motivation. Highly motivated children then encouraged parents to continue involvement. The cyclic nature of this process across elementary school was observed. The model accounted for 61% of the variance in 6th grade achievement. Findings suggest that early parent involvement promoted in the CPC program, sets the stage for subsequent parent involvement, student motivation, and academic achievement throughout early and middle childhood. PMID:27867317
A path analysis model of factors influencing children's requests for unhealthy foods.
Pettigrew, Simone; Jongenelis, Michelle; Miller, Caroline; Chapman, Kathy
2017-01-01
Little is known about the complex combination of factors influencing the extent to which children request unhealthy foods from their parents. The aim of this study was to develop a comprehensive model of influencing factors to provide insight into potential methods of reducing these requests. A web panel provider was used to administer a national online survey to a sample of 1302 Australian parent-child dyads (total sample n=2604). Initial univariate analyses identified potential predictors of children's requests for and consumption of unhealthy foods. The identified variables were subsequently incorporated into a path analysis model that included both parents' and children's reports of children's requests for unhealthy foods. The resulting model accounted for a substantial 31% of the variance in parent-reported food request frequency and 27% of the variance in child-reported request frequency. The variable demonstrating the strongest direct association with both parents' and children's reports of request frequency was the frequency of children's current intake of unhealthy foods. Parents' and children's exposure to food advertising and television viewing time were also positively associated with children's unhealthy food requests. The results highlight the need to break the habitual provision of unhealthy foods to avoid a vicious cycle of requests resulting in consumption.
Stigmatization and self-determination of preregistration nurses: A path analysis.
Perlman, Dana; Brighton, Renee; Patterson, Christopher; Moxham, Lorna; Taylor, Ellie K; Sumskis, Susan; Heffernan, Tim
2017-04-20
The concept of stigma and the stigmatizing behaviours of health-care professionals can have a profound influence on people with mental illness. A key construct that has been identified as influencing our behaviours is self-determination. As such, in the present study, we attempted to examine the connection and influence of motivational measures on the stigmatization of preregistration nurses. Data were collected once using three surveys that measured the motivational responses and stigmatizing behaviours of preregistration nurses after an approved mental health clinical placement. Using a path analysis, the results indicated that psychological needs significantly influenced preregistration nurses' self-determination towards work. In addition, self-determination was a significant influence on the stigmatization behaviours of preregistration nurses. The results of the present study provide initial empirical evidence that supports the importance of professional self-determination and the potential connection of quality care, as illustrated with the low stigmatizing behaviours of preregistration nurses who are more self-determined towards their work/career. Because of the significant results of the present study, it is recommended that future research is needed that uses self-determination theory as a lens to understand the application and importance within the field of nurse education. © 2017 Australian College of Mental Health Nurses Inc.
Path-following analysis of the dynamical response of a piecewise-linear capsule system
NASA Astrophysics Data System (ADS)
Páez Chávez, Joseph; Liu, Yang; Pavlovskaia, Ekaterina; Wiercigroch, Marian
2016-08-01
The dynamical response of a piecewise-linear capsule system is studied by means of path-following techniques in this paper. As the capsule model belongs to the class of piecewise-smooth dynamical systems involving impact and friction, a special care is taken in order to divide the trajectory of the system into a smooth vector field in each disjoint subregion. Specifically we study a two-sided drifting system focusing on directional control and energy consumption. We aim to address two practical problems which are maximizing the rate of progression and directional control of the system by following a typical period-1 trajectory. The one-parameter analysis shows that two types of bifurcations, grazing bifurcation and boundary-intersection crossing bifurcation are found, and the maximal rate of progression is achieved when the capsule performs the oscillations without sticking phases. In our two-parameter study, the control parameters for which the rate of progression is maximal are identified using fixed value of power consumption, and the curves which divide the motion of the capsule between forward and backward progression are obtained.
The Longitudinal Process of Early Parent Involvement on Student Achievement: A Path Analysis.
Hayakawa, Momoko; Englund, Michelle M; Warner-Richter, Mallory N; Reynolds, Arthur J
2013-01-01
This longitudinal study investigated the process whereby early parent involvement in preschool effects student achievement from kindergarten through 6(th) grade. Participants were 1,539 low-income, mainly African American children and their mothers, in the Chicago Longitudinal Study. Program children (N = 989) received one or two years of the Child-Parent Center (CPC) program - a preschool intervention that strongly promoted parents' development of parent involvement skills within the school and at home. Children from similar backgrounds who did not attend the CPC, but participated in available local resources (e.g. day care), were obtained as a comparison group (N = 550). Path analysis revealed an interactive process between parent involvement, academic achievement, and children's motivation. Early parent involvement directly influenced kindergarten achievement, which in turn influenced first grade student motivation. Highly motivated children then encouraged parents to continue involvement. The cyclic nature of this process across elementary school was observed. The model accounted for 61% of the variance in 6(th) grade achievement. Findings suggest that early parent involvement promoted in the CPC program, sets the stage for subsequent parent involvement, student motivation, and academic achievement throughout early and middle childhood.
The Promotion Strategy of Green Construction Materials: A Path Analysis Approach
Huang, Chung-Fah; Chen, Jung-Lu
2015-01-01
As one of the major materials used in construction, cement can be very resource-consuming and polluting to produce and use. Compared with traditional cement processing methods, dry-mix mortar is more environmentally friendly by reducing waste production or carbon emissions. Despite the continuous development and promotion of green construction materials, only a few of them are accepted or widely used in the market. In addition, the majority of existing research on green construction materials focuses more on their physical or chemical characteristics than on their promotion. Without effective promotion, their benefits cannot be fully appreciated and realized. Therefore, this study is conducted to explore the promotion of dry-mix mortars, one of the green materials. This study uses both qualitative and quantitative methods. First, through a case study, the potential of reducing carbon emission is verified. Then a path analysis is conducted to verify the validity and predictability of the samples based on the technology acceptance model (TAM) in this study. According to the findings of this research, to ensure better promotion results and wider application of dry-mix mortar, it is suggested that more systematic efforts be invested in promoting the usefulness and benefits of dry-mix mortar. The model developed in this study can provide helpful references for future research and promotion of other green materials. PMID:28793613
The Promotion Strategy of Green Construction Materials: A Path Analysis Approach.
Huang, Chung-Fah; Chen, Jung-Lu
2015-10-14
As one of the major materials used in construction, cement can be very resource-consuming and polluting to produce and use. Compared with traditional cement processing methods, dry-mix mortar is more environmentally friendly by reducing waste production or carbon emissions. Despite the continuous development and promotion of green construction materials, only a few of them are accepted or widely used in the market. In addition, the majority of existing research on green construction materials focuses more on their physical or chemical characteristics than on their promotion. Without effective promotion, their benefits cannot be fully appreciated and realized. Therefore, this study is conducted to explore the promotion of dry-mix mortars, one of the green materials. This study uses both qualitative and quantitative methods. First, through a case study, the potential of reducing carbon emission is verified. Then a path analysis is conducted to verify the validity and predictability of the samples based on the technology acceptance model (TAM) in this study. According to the findings of this research, to ensure better promotion results and wider application of dry-mix mortar, it is suggested that more systematic efforts be invested in promoting the usefulness and benefits of dry-mix mortar. The model developed in this study can provide helpful references for future research and promotion of other green materials.
Transfer path analysis: Current practice, trade-offs and consideration of damping
NASA Astrophysics Data System (ADS)
Oktav, Akın; Yılmaz, Çetin; Anlaş, Günay
2017-02-01
Current practice of experimental transfer path analysis is discussed in the context of trade-offs between accuracy and time cost. An overview of methods, which propose solutions for structure borne noise, is given, where assumptions, drawbacks and advantages of methods are stated theoretically. Applicability of methods is also investigated, where an engine induced structure borne noise of an automobile is taken as a reference problem. Depending on this particular problem, sources of measurement errors, processing operations that affect results and physical obstacles faced in the application are analysed. While an operational measurement is common in all stated methods, when it comes to removal of source, or the need for an external excitation, discrepancies are present. Depending on the chosen method, promised outcomes like independent characterisation of the source, or getting information about mounts also differ. Although many aspects of the problem are reported in the literature, damping and its effects are not considered. Damping effect is embedded in the measured complex frequency response functions, and it is needed to be analysed in the post processing step. Effects of damping, reasons and methods to analyse them are discussed in detail. In this regard, a new procedure, which increases the accuracy of results, is also proposed.
Stress optical path difference analysis of off-axis lens ray trace footprint
NASA Astrophysics Data System (ADS)
Hsu, Ming-Ying; Chan, Chia-Yen; Lin, Wei-Cheng; Wu, Kun-Huan; Chen, Chih-Wen; Chan, Shenq-Tsong; Huang, Ting-Ming
2013-06-01
The mechanical and thermal stress on lens will cause the glass refractive index different, the refractive index of light parallel and light perpendicular to the direction of stress. The refraction index changes will introduce Optical Path Difference (OPD). This study is applying Finite Element Method (FEM) and optical ray tracing; calculate off axis ray stress OPD. The optical system stress distribution result is calculated from finite element simulation, and the stress coordinate need to rotate to optical path direction. Meanwhile, weighting stress to each optical ray path and sum the ray path OPD. The Z-direction stress OPD can be fitted by Zernike polynomial, the separated to sag difference, and rigid body motion. The fitting results can be used to evaluate the stress effect on optical component.
Granular clustering: self-consistent analysis for general coefficients of restitution.
Thiesen, E; Morgado, W A M
2006-05-01
We study the equilibrium behavior of one-dimensional granular clusters and one-particle granular gases for a variety of velocity-dependent coefficients of restitution r. We obtain equations describing the long-time behavior for the cluster's pressure, rms velocity, and granular interspacing. We show that for extremely long times, clusters with velocity-dependent coefficients of restitution are unstable and dissolve into homogeneous, quasielastic gases, but clusters with velocity-independent r are permanent. This is in accordance with hydrodynamic studies pointing to the transient nature of density instabilities for granular gases with velocity-dependent r.
Using wave intensity analysis to determine local reflection coefficient in flexible tubes.
Li, Ye; Parker, Kim H; Khir, Ashraf W
2016-09-06
It has been shown that reflected waves affect the shape and magnitude of the arterial pressure waveform, and that reflected waves have physiological and clinical prognostic values. In general the reflection coefficient is defined as the ratio of the energy of the reflected to the incident wave. Since pressure has the units of energy per unit volume, arterial reflection coefficient are traditionally defined as the ratio of reflected to the incident pressure. We demonstrate that this approach maybe prone to inaccuracies when applied locally. One of the main objectives of this work is to examine the possibility of using wave intensity, which has units of energy flux per unit area, to determine the reflection coefficient. We used an in vitro experimental setting with a single inlet tube joined to a second tube with different properties to form a single reflection site. The second tube was long enough to ensure that reflections from its outlet did not obscure the interactions of the initial wave. We generated an approximately half sinusoidal wave at the inlet of the tube and took measurements of pressure and flow along the tube. We calculated the reflection coefficient using wave intensity (RdI and RdI(0.5)) and wave energy (RI and RI(0.5)) as well as the measured pressure (RdP) and compared these results with the reflection coefficient calculated theoretically based on the mechanical properties of the tubes. The experimental results show that the reflection coefficients determined by all the techniques we studied increased or decreased with distance from the reflection site, depending on the type of reflection. In our experiments, RdP, RdI(0.5) and RI(0.5) are the most reliable parameters to measure the mean reflection coefficient, whilst RdI and RI provide the best measure of the local reflection coefficient, closest to the reflection site. Additional work with bifurcations, tapered tubes and in vivo experiments are needed to further understand, validate the method
Group analysis of Benjamin—Bona—Mahony equations with time dependent coefficients
NASA Astrophysics Data System (ADS)
Vaneeva, Olena; Popovych, Roman O.; Sophocleous, Christodoulos
2015-06-01
Group classification of a class of Benjamin-Bona-Mahony (BBM) equations with time dependent coefficients is carried out. Two equivalent lists of equations possessing Lie symmetry extensions are presented: up to point equivalence within the class of BBM equations and without the simplification by equivalence transformations. It is shown that the complete results can be achieved using either the gauging of arbitrary elements of the class by the equivalence transformations or the method of mapping between classes. As by-product of the second approach the complete group classification of a class of variable-coefficient BBM equations with forcing term is derived.
NASA Astrophysics Data System (ADS)
Abdelrahman, Awad; Mamat, Mustafa; Rivaie, Mohd; Omer, Osman
2015-05-01
Nonlinear conjugate gradient (CG) methods are the most important method for solving large-scale unconstrained optimization problems. Many studies and modifications have been conducted recently to improve this method. In this paper, a new class of conjugate gradient coefficients (βk ) with a new parameter m =‖gk ‖ /‖gk -1 ‖ that possess global convergence properties is presented. The global convergence and sufficient decent property result is established using inexact line searches to determine the (αk>0 ) is a step size of CG methods. Numerical result shows that the new formula is superior and more efficient when compared to other CG coefficients.
Vehicle wheel drag coefficient in relation to travelling velocity - CFD analysis
NASA Astrophysics Data System (ADS)
Leśniewicz, P.; Kulak, M.; Karczewski, M.
2016-10-01
In order to understand the aerodynamic losses associated with a rotating automobile wheel, a detailed characteristics of the drag coefficient in relation to the applied velocity are necessary. Single drag coefficient value is most often reported for the commercially available vehicles, much less is revealed about the influence of particular car components on the energy consumption in various driving cycles. However, detailed flow potential losses determination is desired for performance estimation. To address these needs, the numerical investigation of an isolated wheel is proposed herein.
PathNet: A Tool for Pathway Analysis Using Topological Information
2012-09-24
relations among pathways. In this study, we used PathNet to identify biologically relevant results in two Alzheimer ?s disease microarray datasets, and...important component in Alzheimer ?s disease progression, despite the absence of this pathway in the standard enrichment analyses. Conclusions: PathNet is a...Honjo K, van Reekum R, Verhoeff NP: Alzheimer’s disease and infection: do infectious agents contribute to progression of Alzheimer’s disease? Alzheimers
De Vico, Luca; Page, Christopher S; Garavelli, Marco; Bernardi, Fernando; Basosi, Riccardo; Olivucci, Massimo
2002-04-17
Multiconfigurational second-order perturbation theory computations and reaction path mapping for the retinal protonated Schiff base models all-trans-nona-2,4,6,8-tetraeniminium and 2-cis-nona-2,4,6,8-tetraeniminium cation demonstrate that, in isolated conditions, retinal chromophores exhibit at least three competing excited-state double bond isomerization paths. These paths are associated with the photoisomerization of the double bonds in positions 9, 11, and 13, respectively, and are controlled by barriers that favor the position 11. The computations provide a basis for the understanding of the observed excited-state lifetime in both naturally occurring and synthetic chromophores in solution and, tentatively, in the protein environment. In particular, we provide a rationalization of the excited-state lifetimes observed for a group of locked retinal chromophores which suggests that photoisomerization in bacteriorhodopsin is the result of simultaneous specific "catalysis" (all-trans --> 13-cis path) accompanied by specific "inhibition" (all-trans --> 11-cis path). The nature of the S(1) --> S(0) decay channel associated with the three paths has also been investigated at the CASSCF level of theory. It is shown that the energy surfaces in the vicinity of the conical intersection for the photoisomerization about the central double bond of retinal (position 11) and the two corresponding lateral double bonds (positions 9 and 13) are structurally different.
Werner, Kent; Bosson, Emma; Berglund, Sten
2006-12-01
Safety assessment related to the siting of a geological repository for spent nuclear fuel deep in the bedrock requires identification of potential flow paths and the associated travel times for radionuclides originating at repository depth. Using the Laxemar candidate site in Sweden as a case study, this paper describes modeling methodology, data integration, and the resulting water flow models, focusing on the Quaternary deposits and the upper 150 m of the bedrock. Example simulations identify flow paths to groundwater discharge areas and flow paths in the surface system. The majority of the simulated groundwater flow paths end up in the main surface waters and along the coastline, even though the particles used to trace the flow paths are introduced with a uniform spatial distribution at a relatively shallow depth. The calculated groundwater travel time, determining the time available for decay and retention of radionuclides, is on average longer to the coastal bays than to other biosphere objects at the site. Further, it is demonstrated how GIS-based modeling can be used to limit the number of surface flow paths that need to be characterized for safety assessment. Based on the results, the paper discusses an approach for coupling the present models to a model for groundwater flow in the deep bedrock.
Bhattacharya, Indrajit; Ramachandran, Anandhi
2015-07-31
Healthcare information technology (HIT) applications are being ubiquitously adopted globally and have been indicated to have effects on certain dimensions of recruitment and retention of healthcare professionals. Retention of healthcare professionals is affected by their job satisfaction (JS), commitment to the organization and intention to stay (ITS) that are interlinked with each other and influenced by many factors related to job, personal, organization, etc. The objectives of the current study were to determine if HIT was one among the factors and, if so, propose a probable retention model that incorporates implementation and use of HIT as a strategy. This was a cross-sectional survey study covering 20 hospitals from urban areas of India. The sample (n = 586) consisted of doctors, nurses, paramedics and hospital administrators. Data was collected through a structured questionnaire. Factors affecting job satisfaction were determined. Technology acceptance by the healthcare professionals was also determined. Interactions between the factors were predicted using a path analysis model. The overall satisfaction rate of the respondents was 51 %. Based on factor analysis method, 10 factors were identified for JS and 9 factors for ITS. Availability and use of information technology was one factor that affected JS. The need for implementing technology influenced ITS through work environment and career growth. Also, the study indicated that nearly 70 % of the respondents had awareness of HIT, but only 40 % used them. The importance of providing training for HIT applications was stressed by many respondents. The results are in agreement with literature studies exploring job satisfaction and retention among healthcare professionals. Our study documented a relatively medium level of job satisfaction among the healthcare professionals in the urban area. Information technology was found to be one among the factors that can plausibly influence their job satisfaction and
Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China
Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming
2015-01-01
Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a
Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China.
Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming
2015-01-01
Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a
Suárez, Inmaculada; Coto, Baudilio
2015-08-14
Average molecular weights and polydispersity indexes are some of the most important parameters considered in the polymer characterization. Usually, gel permeation chromatography (GPC) and multi angle light scattering (MALS) are used for this determination, but GPC values are overestimated due to the dispersion introduced by the column separation. Several procedures were proposed to correct such effect usually involving more complex calibration processes. In this work, a new method of calculation has been considered including diffusion effects. An equation for the concentration profile due to diffusion effects along the GPC column was considered to be a Fickian function and polystyrene narrow standards were used to determine effective diffusion coefficients. The molecular weight distribution function of mono and poly disperse polymers was interpreted as a sum of several Fickian functions representing a sample formed by only few kind of polymer chains with specific molecular weight and diffusion coefficient. Proposed model accurately fit the concentration profile along the whole elution time range as checked by the computed standard deviation. Molecular weights obtained by this new method are similar to those obtained by MALS or traditional GPC while polydispersity index values are intermediate between those obtained by the traditional GPC combined to Universal Calibration method and the MALS method. Values for Pearson and Lin coefficients shows improvement in the correlation of polydispersity index values determined by GPC and MALS methods when diffusion coefficients and new methods are used.
Bootsie: estimation of coefficient of variation of AFLP data by bootstrap analysis
USDA-ARS?s Scientific Manuscript database
Bootsie is an English-native replacement for ASG Coelho’s “DBOOT” utility for estimating coefficient of variation of a population of AFLP marker data using bootstrapping. Bootsie improves on DBOOT by supporting batch processing, time-to-completion estimation, built-in graphs, and a suite of export t...
USDA-ARS?s Scientific Manuscript database
Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial deterioration of both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (Keff) between impure sucrose syrup and crystal has been investigated in a batch laboratory c...
Measurement and analysis of the dextran partition coefficient in sucrose crystallization
NASA Astrophysics Data System (ADS)
Promraksa, Arwut; Flood, Adrian E.; Schneider, Philip A.
2009-07-01
The effect of crystallization conditions on the dextran partition coefficient between impure syrup and sugar crystal has been investigated in a batch crystallizer. The crystallizer is operated isothermally at temperatures of 30, 40, and 50 °C, at constant relative supersaturations of 0.05, 0.07, and 0.09, and with mother liquor dextran concentrations of 1000 and 2000 ppm/Brix. The dextran content has been determined by the CSR method. A 1:1 mass ratio of high-fraction dextran (approximately 250,000 Da) and low-fraction dextran (60,000-90,000 Da) is used to represent a wide range of dextran contamination. It is seen that the dextran partition coefficient in sucrose crystallization increases with both increasing supersaturation and increasing crystallization temperature. However it appears that these are secondary effects, with the partition coefficient strongly correlating with crystal growth rate alone, despite the regressed data having large variations in temperature, mother liquor dextran content, and supersaturation. Dextran incorporation into the sugar crystal results from both dextran adsorption onto the crystal surface and mother liquor inclusions. The explanation for the variation in the dextran content in sugar crystal with respect to the growth rate is due to increased adsorption due to the higher surface roughness of crystals grown at high growth rates. Although the dextran concentration in the solution affects the dextran content in the crystal, it does not strongly affect the dextran partition coefficient.
Analysis of oscillatory motion of a light airplane at high values of lift coefficient
NASA Technical Reports Server (NTRS)
Batterson, J. G.
1983-01-01
A modified stepwise regression is applied to flight data from a light research air-plane operating at high angles at attack. The well-known phenomenon referred to as buckling or porpoising is analyzed and modeled using both power series and spline expansions of the aerodynamic force and moment coefficients associated with the longitudinal equations of motion.
Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients
ERIC Educational Resources Information Center
Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako
2012-01-01
Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…
Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients
ERIC Educational Resources Information Center
Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako
2012-01-01
Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…
Price, D.E.; Brereton, S.; Newton, M.; Moore, B.; Muirhead, D.; Pastrnak, J.; Prokosch, D.; Spence, B.; Towle, R.
2000-09-05
POV-Ray Ricochet Tracker is a freeware computer code developed to analyze high-speed fragment ricochet trajectory paths in complex 3-D areas such as explosives tiring chambers, facility equipment rooms, or shipboard Command and Control Centers. The code analyzes as many as millions of individual fragment trajectory paths in three dimensions and tracks these trajectory paths for up to four bounces through the three-dimensional model. It allows determination of the probabilities of hitting any designated areas or objects in the model. It creates renderings of any ricochet flight paths of interest in photo realistic renderings of the 3-D model. POV-Ray Ricochet Tracker is a customized version of the Persistence of Vision{trademark} Ray-Tracer (POV-Ray{trademark}) version 3.02 code for the Macintosh{trademark} Operating System (MacOS{trademark}). POV-Ray is a third generation graphics engine that creates three-dimensional, very high quality (photo-realistic) images with realistic reflections, shading, textures, perspective, and other effects using a rendering technique called ray-tracing. It reads a text tile that describes the objects, lighting, and camera location in a scene and generates an image of that scene from the viewpoint of the camera. More information about POV-Ray, including the executable and source code, may be found at http://www.povray.org. The customized code (POV-Ray Shrapnel Tracker, V3.02-Custom Build 2) generates individual fragment trajectory paths at any desired angle intervals in three dimensions. The code tracks these trajectory paths through any complex three-dimensional space, and outputs detailed data for each ray as requested by the user. The output may include trajectory source location, initial direction of each trajectory, vector data for each bounce point, and any impacts with designated model target surfaces during any trajectory segment (direct path or reflected paths). This allows determination of the three-dimensional trajectory of
Analysis of strain paths of sheared edges during hole expansion tests
NASA Astrophysics Data System (ADS)
Koebel, Philipp; Van Tyne, Chester J.; Hora, Pavel; Manopulo, Niko
2013-12-01
One of the limitations to the widespread use of advanced high strength steel (AHSS) sheets is the cracking of sheared edges during subsequent stretching operations, as nearly all stamped parts are sheared prior to sheet forming. Cracking at the edge occurs at levels below the conventional forming limit criteria. Understanding the strain path of the sheared edge during a hole expansion test should provide insight into the strain path of a sheared edge when it is stretched during production. As a result, experimental as well as finite element simulations are used for analyzing the strain path behavior of a sheared edge during hole expansion tests. The shearing process changes the global behavior in the sheet during a hole expansion, and the finite element results indicate that the strain paths for points near the edge of the hole during expansion are non-linear due to the presence of the shear affected zone (SAZ). These results are consistent with previously measured experimental values for the strain path.
Job Stress and Related Factors Among Iranian Male Staff Using a Path Analysis Model
Azad-Marzabadi, Esfandiar; Gholami Fesharaki, Mohammad
2016-01-01
Background In recent years, job stress has been cited as a risk factor for some diseases. Objectives Given the importance of this subject, we established a new model for classifying job stress among Iranian male staff using path analysis. Materials and Methods This cross-sectional study was done on male staff in Tehran, Iran, 2013. The participants in the study were selected using a proportional stratum sampling method. The tools used included nine questionnaires (1- HSE questionnaire; 2- GHQ questionnaire; 3- Beck depression inventory; 4- Framingham personality type; 5- Azad-Fesharaki’s physical activity questionnaire; 6- Adult attachment style questionnaire; 7- Azad socioeconomic questionnaire; 8- Job satisfaction survey; and 9- demographic questionnaire). Results A total of 575 individuals (all male) were recruited for the study. Their mean (±SD) age was 33.49 (±8.9) and their mean job experience was 12.79 (±8.98) years. The pathway of job stress among Iranian male staff showed an adequate model fit (RMSEA=0.021, GFI=0.99, AGFI=0.97, P=0.136). In addition, the total effect of variables like personality type (β=0.283), job satisfaction (β=0.287), and age (β=0.108) showed a positive relationship with job stress, while variables like general health (β=-0.151) and depression (β=-0.242) showed the reverse effect on job stress. Conclusions According to the results of this study, we can conclude that our suggested model is suited to explaining the pathways of stress among Iranian male staff. PMID:27621934
Ling, Jiying; Robbins, Lorraine B; McCarthy, Valerie Lander; Speck, Barbara J
2015-01-01
Physical activity (PA) is important for controlling childhood obesity, but a comprehensive PA model for school-aged children is lacking. Guided by the youth PA promotion (YPAP) model, this study estimated the direct and indirect effects of self-efficacy, enjoyment, parental influence, and environment on self-reported PA and pedometer steps. A secondary purpose was to explore the association between self-reported PA and pedometer steps. An observational and prospective study was conducted among 133 children, aged 8-11 years old, from 10 elementary schools with afterschool programs in a Midwestern U.S. school district from August through October 2013. PA was assessed by a 7-day recall scale and pedometers. Other variables were assessed by validated questionnaires. Approximately 65 (49%) children were overweight or obese-only 17 (13%) met national PA recommendations-and body mass index z-score was negatively correlated with pedometer steps (r = -.18 p = .04). A path analysis showed that self-efficacy had a direct effect on self-reported PA and pedometer steps, enjoyment had only a direct effect on self-reported PA, and parental influence had a direct effect on pedometer steps and an indirect effect on self-reported PA through self-efficacy and enjoyment. The association between self-reported PA and pedometer steps was not significant. Because this study only partially supports the YPAP model, studies with a larger sample size and longitudinal design are essential to further examine this model. The nonsignificant relationship of self-reported PA with pedometer steps may be due to the systematic error resulting from a common method artifact of self-report. Given the importance of parental influence, enjoyment, and self-efficacy, targeting these three determinants in future interventions to increase PA among children is recommended.
Zarillo, G.A.; Liu, T.C.; Tsien, H.S.; Zimmerman, M.S.
1985-02-01
Recent geomorphic evidence from the inner shelf and shoreface to the east of Long Island's barrier island system indicates that reworking of glacial outwash deposits at the inner shelf-shoreface transition, as sea level rises, may be supplying much of the sediment needed to maintain barrier island to the west. A conceptual model describing sediment dispersal from outwash source areas was developed from this hypothesis. It was reasoned that outwash sediments ranging from silts to coarse gravels would be subject to differential transport paths across and along the shoreface upon reworking. Coarser grain sizes would move onshore toward the intertidal beach, whereas finer sediments would move offshore. Sand of intermediate grain size would be concentrated in the surf zone and move alongshore in wave-generated longshore currents. To test this model, 400 samples from the beach and shoreface of Long Island were analyzed for grain-size frequency distribution and each grain-size class was examined for frequency of occurrence in the cross-shore and alongshore directions. On a spatially averaged basis, grain-size classes displayed peak abundance in specific zones across the shoreface as predicted by the model, but alongshore trends could not be recognized among the noisy data. Therefore, empirical orthogonal functions (EOF) were used to examine uncorrelated modes of variability in the occurrence of each grain-size class in the alongshore direction. The first function, representing more than 60% of the variability among the data, showed that grain sizes subject to longshore transport in the surf zone increase in frequency in the alongshore direction relative to coarser grain sizes. Results also show that peak concentrations of coarse sediments correspond to zones subject to frequent overwashing. It is concluded that EOF analysis of individual grain-size classes holds promise for extracting trends from noisy data sets.
Slip flow coefficient analysis in water hydraulics gear pump for environmental friendly application
NASA Astrophysics Data System (ADS)
Yusof, A. A.; Wasbari, F.; Zakaria, M. S.; Ibrahim, M. Q.
2013-12-01
Water hydraulics is the sustainable option in developing fluid power systems with environmental friendly approach. Therefore, an investigation on water-based external gear pump application is being conducted, as a low cost solution in the shifting effort of using water, instead of traditional oil hydraulics in fluid power application. As the gear pump is affected by fluid viscosity, an evaluation has been conducted on the slip flow coefficient, in order to understand to what extent the spur gear pump can be used with water-based hydraulic fluid. In this paper, the results of a simulated study of variable-speed fixed displacement gear pump are presented. The slip flow coefficient varies from rotational speed of 250 RPM to 3500 RPM, and provides volumetric efficiency ranges from 9 % to 97% accordingly.
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.
NASA Astrophysics Data System (ADS)
Riquelme, Rodrigo; Lira, Ignacio; Pérez-López, Carlos; Rayas, Juan A.; Rodríguez-Vera, Ramón
2007-05-01
Two methods to measure the diffusion coefficient of a species in a liquid by optical interferometry were compared. The methods were tested on a 1.75 M NaCl aqueous solution diffusing into water at 26 °C. Results were D = 1.587 × 10-9 m2 s-1 with the first method and D = 1.602 × 10-9 m2 s-1 with the second method. Monte Carlo simulation was used to assess the possible dispersion of these results. The standard uncertainties were found to be of the order of 0.05 × 10-9 m2 s-1 with both methods. We found that the value of the diffusion coefficient obtained by either method is very sensitive to the magnification of the optical system, and that if diffusion is slow the measurement of time does not need to be very accurate.
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.
NASA Astrophysics Data System (ADS)
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.
Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System
NASA Technical Reports Server (NTRS)
Welch, Bryan
2004-01-01
This paper investigates the optimization of an orbit for a Low-Earth Orbiting (LEO) satellite for coastal coverage over Antarctic and United States shorelines as part of the Geostationary/Low-Earth Orbiting Radar Image Acquisition (GLORIA) System. Simulations over a range of orbital parameters are performed to determine the optimal orbit. Scattering coefficients are computed for the optimal orbit throughout the day and characterized to compare various scenarios for which link budget comparisons could then be made.
Umanodan, Tomokazu; Fukukura, Yoshihiko; Kumagae, Yuichi; Shindo, Toshikazu; Nakajo, Masatoyo; Takumi, Koji; Nakajo, Masanori; Hakamada, Hiroto; Umanodan, Aya; Yoshiura, Takashi
2017-04-01
To determine the diagnostic performance of apparent diffusion coefficient (ADC) histogram analysis in diffusion-weighted (DW) magnetic resonance imaging (MRI) for differentiating adrenal adenoma from pheochromocytoma. We retrospectively evaluated 52 adrenal tumors (39 adenomas and 13 pheochromocytomas) in 47 patients (21 men, 26 women; mean age, 59.3 years; range, 16-86 years) who underwent DW 3.0T MRI. Histogram parameters of ADC (b-values of 0 and 200 [ADC200 ], 0 and 400 [ADC400 ], and 0 and 800 s/mm(2) [ADC800 ])-mean, variance, coefficient of variation (CV), kurtosis, skewness, and entropy-were compared between adrenal adenomas and pheochromocytomas, using the Mann-Whitney U-test. Receiver operating characteristic (ROC) curves for the histogram parameters were generated to differentiate adrenal adenomas from pheochromocytomas. Sensitivity and specificity were calculated by using a threshold criterion that would maximize the average of sensitivity and specificity. Variance and CV of ADC800 were significantly higher in pheochromocytomas than in adrenal adenomas (P < 0.001 and P = 0.001, respectively). With all b-value combinations, the entropy of ADC was significantly higher in pheochromocytomas than in adrenal adenomas (all P ≤ 0.001), and showed the highest area under the ROC curve among the ADC histogram parameters for diagnosing adrenal adenomas (ADC200 , 0.82; ADC400 , 0.87; and ADC800 , 0.92), with sensitivity of 84.6% and specificity of 84.6% (cutoff, ≤2.82) with ADC200 ; sensitivity of 89.7% and specificity of 84.6% (cutoff, ≤2.77) with ADC400 ; and sensitivity of 94.9% and specificity of 92.3% (cutoff, ≤2.67) with ADC800 . ADC histogram analysis of DW MRI can help differentiate adrenal adenoma from pheochromocytoma. 3 J. Magn. Reson. Imaging 2017;45:1195-1203. © 2016 International Society for Magnetic Resonance in Medicine.
Ab initio MO analysis of interaction paths between radicals in ferromagnetic organic systems.
Orimoto, Yuuichi; Imai, Takahiro; Naka, Kazunari; Aoki, Yuriko
2006-05-04
Interaction path analyses for pi-conjugated organic systems were performed at the ab initio molecular orbital level to examine the relationship between inter-radical interactions and the high-spin stability of the system. It was found that the high-spin stability results from through-bond interactions between radicals, not from through-space interactions, in relation to the stabilization of a low-spin state due to the effects of electron correlation. L(ij)(min) value for estimating the mixing of nonbonding molecular orbitals well predicted the relationship between the through-bond interactions and the high-spin stability. Furthermore, molecular orbital calculations revealed that the all-trans type interaction path between radicals produces long-range exchange interactions, and the additivity of high-spin stability is observed by keeping short-range through-bond interaction paths.
Analysis of lifetime of wireless sensor network with base station moving on different paths
NASA Astrophysics Data System (ADS)
Singh, Ashutosh Kumar; Purohit, N.; Varma, S.
2014-05-01
Energy saving is the top most requirement of the wireless sensor network (WSN) for making it a cost effective technology. In this direction, minimisation of the distance between the communicating nodes should be an obvious choice, as it consumes the biggest chunk of the node energy. But the stationary nature of nodes (including the base station) in the standard WSN does not allow it; thus, the provision of a moving base station has been recently introduced. A few schemes with moving base station have already been developed but they suffer from several drawbacks, for example, the path over which the base station can move has not been considered which is highly unfeasible. An efficient and implementable moving strategy is needed to be developed, which is the primary goal of the present work. The fuzzy logic inference mechanism has been developed and the performance of the same is illustrated in terms of WSN lifetime. Lifetime of a WSN depends on many factors, for example, residual energy of nodes, distance between communicating nodes and base station, etc. Ability of fuzzy logic theory to address more than one factor simultaneously gives it an upper edge over other alternatives. The present work explores the possibilities of building either a circular shaped or a cross-shaped path in the deployment area. A relative study of the movement of base station on these paths has been presented. Simulation results show that the cross path always give better performance than circular path and the lifetime improves with increase in the length of the predefined path.
NASA Technical Reports Server (NTRS)
Ruf, Joseph H.
1992-01-01
Phase 2+ Space Shuttle Main Engine powerheads, E0209 and E0215 degraded their main combustion chamber (MCC) liners at a faster rate than is normal for phase 2 powerheads. One possible cause of the accelerated degradation was a reduction of coolant flow through the MCC. Hardware changes were made to the preburner fuel leg which may have reduced the resistance and, therefore, pulled some of the hydrogen from the MCC coolant leg. A computational fluid dynamics (CFD) analysis was performed to determine hydrogen flow path resistances of the phase 2+ fuel preburner injector elements relative to the phase 2 element. FDNS was implemented on axisymmetric grids with the hydrogen assumed to be incompressible. The analysis was performed in two steps: the first isolated the effect of the different inlet areas and the second modeled the entire injector element hydrogen flow path.
NASA Astrophysics Data System (ADS)
Pelkey, Ramona K.
Gender, ethnicity, family economic status, reading score, mathematics score, and number of science semesters successfully completed were examined for their contributory role to a student's science score on a high-stakes, high school exit examination. Path analysis and analysis of variance procedures were used to quantify each variable's influence on science score. Gender, ethnicity, and family economic status were found to be moderators while reading proved to mediate within the model. The path model was created using a calibration sample and cross-validated using a hold-out validation sample. Bootstrapping was used to verify the goodness of fit of the model. A predictive equation explained 66% (R2 = .66) of the variance in observed TAKS science score.
Liu, An-Nuo; Wang, Lu-Lu; Li, Hui-Ping; Gong, Juan; Liu, Xiao-Hong
2017-05-01
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.
Zheng, Han-Qin; Chiang-Hsieh, Yi-Fan; Chien, Chia-Hung; Hsu, Bo-Kai Justin; Liu, Tsung-Lin; Chen, Ching-Nen Nathan; Chang, Wen-Chi
2014-03-14
Algae are important non-vascular plants that have many research applications, including high species diversity, biofuel sources, and adsorption of heavy metals and, following processing, are used as ingredients in health supplements. The increasing availability of next-generation sequencing (NGS) data for algae genomes and transcriptomes has made the development of an integrated resource for retrieving gene expression data and metabolic pathway essential for functional analysis and systems biology. In a currently available resource, gene expression profiles and biological pathways are displayed separately, making it impossible to easily search current databases to identify the cellular response mechanisms. Therefore, in this work the novel AlgaePath database was developed to retrieve transcript abundance profiles efficiently under various conditions in numerous metabolic pathways. AlgaePath is a web-based database that integrates gene information, biological pathways, and NGS datasets for the green algae Chlamydomonas reinhardtii and Neodesmus sp. UTEX 2219-4. Users can search this database to identify transcript abundance profiles and pathway information using five query pages (Gene Search, Pathway Search, Differentially Expressed Genes (DEGs) Search, Gene Group Analysis, and Co-expression Analysis). The transcript abundance data of 45 and four samples from C. reinhardtii and Neodesmus sp. UTEX 2219-4, respectively, can be obtained directly on pathway maps. Genes that are differentially expressed between two conditions can be identified using Folds Search. The Gene Group Analysis page includes a pathway enrichment analysis, and can be used to easily compare the transcript abundance profiles of functionally related genes on a map. Finally, the Co-expression Analysis page can be used to search for co-expressed transcripts of a target gene. The results of the searches will provide a valuable reference for designing further experiments and for elucidating critical
Endo, Satoshi
2016-08-10
Narcosis occurs as a result of the accumulation of chemicals in the phospholipid membrane. The toxic threshold concentration in the membrane is thought to be relatively constant across different chemicals and species. Hence, estimating chemical concentrations in the membrane is expected to reduce the variability of narcotic critical body residue (CBR) data. In this study, a high quality CBR dataset for three aquatic species reported recently in the literature was evaluated with the internal equilibrium distribution concept. The raw wet-weight-based CBR values were converted to membrane-weight-based CBR values by assuming that the chemical is distributed in storage lipids, membranes, proteins, and water according to the respective equilibrium partition coefficients. Several sets of partition coefficients were compared for this analysis. The results were consistent with the notion that the use of a structural protein instead of serum albumin as a surrogate for the body protein fraction could reduce the variability of CBRs. Partition coefficients predicted by polyparameter linear free energy relationships (PP-LFERs) reduced the variability of CBRs as much as or even more than experimental partition coefficients did. It is suggested that CBR data for chemicals with larger structural diversity and biological species with more distinct compositions are needed to evaluate further the equilibrium distribution concept and the constant membrane threshold hypothesis.
Dalirsefat, Seyed Benyamin; da Silva Meyer, Andréia; Mirhoseini, Seyed Ziyaeddin
2009-01-01
Establishing accurate genetic similarity and dissimilarity between individuals is an essential and decisive point for clustering and analyzing inter and intra population diversity because different similarity and dissimilarity indices may yield contradictory outcomes. We assessed the variations caused by three commonly used similarity coefficients including Jaccard, Sorensen-Dice and Simple matching in the clustering and ordination of seven Iranian native silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), strains analyzed by amplified fragment length polymorphism markers. Comparisons among the similarity coefficients were made using the Spearman correlation analysis, dendrogram evaluation (visual inspection and consensus fork index - CIC), projection efficiency in a two-dimensional space, and groups formed by the Tocher optimization procedure. The results demonstrated that for almost all methodologies, the Jaccard and Sorensen-Dice coefficients revealed extremely close results, because both of them exclude negative co-occurrences. Due to the fact that there is no guarantee that the DNA regions with negative cooccurrences between two strains are indeed identical, the use of coefficients such as Jaccard and Sorensen-Dice that do not include negative co-occurrences was imperative for closely related organisms. PMID:20050782
Bennell, Craig; Gauthier, Donna; Gauthier, Donald; Melnyk, Tamara; Musolino, Evanya
2010-06-15
In order to determine whether a series of unsolved crimes has been committed by the same offender, the police often must rely on an analysis of behavioural evidence. When carrying out this task, some type of similarity coefficient is typically relied on to assess the degree of behavioural stability and distinctiveness that exists across a set of crimes and questions inevitably arise as to which coefficient to use. In cases of juvenile sex offences, research has suggested that a taxonomic similarity index outperforms the most commonly used metric at the moment, Jaccard's coefficient, especially under conditions of data degradation (missing data). However, recent research has failed to replicate this result in cases of serial homicide and burglary, especially when relatively large sample sizes are used. The current study provides further support for these recent findings using adult serial sexual assault data. Across a range of conditions, the current study demonstrates that Jaccard's coefficient slightly outperforms the taxonomic similarity index on a measure of linking accuracy. Potential explanations for the results are provided, implications are discussed, and future research directions are presented. (c) 2010 Elsevier Ireland Ltd. All rights reserved.
Tokuda, Yasuharu; Hayano, Keiko; Ozaki, Makiko; Bito, Seiji; Yanai, Haruo; Koizumi, Shunzo
2009-04-01
A growing number of physicians are leaving their hospitals because of painful working conditions in hospitals throughout Japan. We set out to analyze the interrelationships between working conditions, job satisfaction, burnout and mental health among Japanese physicians. A cross-sectional survey was conducted in 2007 for hospital physicians throughout Japan. A path analysis based on structural equation modeling was utilized for examining the interrelationships between work control, on-call duty volume, job satisfaction (the Japan Hospital Physicians Satisfaction Scale), burnout (the Japanese version of the Maslach Burnout Inventory) and mental health (the General Health Questionnaire). Of 336 physicians who received a solicitation E-mail, 236 participated in our study (response rate, 70%). Sixty physicians (25.4%) were women with a mean age of 41 yr. In the path analysis, burnout and poor mental health were related directly to job dissatisfaction and short sleeping time, while they were related indirectly to poor work control and heavy on-call duty. In the multi-group path analysis of both genders, sleeping time was related to job satisfaction more likely among female physicians but less among male physicians. Healthcare policy makers need to implement immediate, extensive and decisive measures to improve work condition and to reduce overwork among hospital physicians.
2004-03-01
coefficients have been found to vary with changes in hematocrit, blood lipids (fasted versus postprandial sampling) and organ lipids (Fiserova-Bergerova...assumed that blood was taken in various fasted or postprandial states depending on the individual. The one to two hour postprandial value (Fiserova...being made up of tissue water, neutral lipids (non-polar lipids including triglycerides and cholesterol ) and phospholipids (lipids with a phosphoric acid
Condensation Coefficient: Definitions, Estimations, Modern Experimental and Calculation Data
NASA Astrophysics Data System (ADS)
Kryukov, A. P.; Levashov, V. Yu.; Pavlyukevich, N. V.
2014-01-01
A brief analysis of different approaches to the calculation and measurement of the condensation coefficient of a vapor is presented. It is shown that, on frequent occasions, calculations give values of this coefficient that are at variance with the corresponding experimental data and that the condensation coefficient is determined most exactly on the basis of the molecular-kinetic theory. It was established that the spread in the literature data on the measured values of this coefficient is explained mainly by the fact that these values were obtained not in the immediate vicinity from the boundary between the gas and liquid phases but at a large distance (as compared to the mean free path of molecules) from it. Results of calculations of the condensation coefficient of argon by the method of moleculardynamic simulation are presented.
Feasibility Analysis of Improving On-Campus Learning Paths via a Depth Sensor
ERIC Educational Resources Information Center
Pan, Wen-Fu; Tu, Shih-Chun; Chien, Mei-Ying
2014-01-01
This research aims to apply a depth sensor to create a human-body-sensing context for outdoor learning paths; it is conducted by incorporating both quasi-experiment and survey to compare students' cognitive learning outcome within the context and understand students' attitudes toward the context created. The result of ANCOVA indicates that the…
Morphological Awareness in Literacy Acquisition of Chinese Second Graders: A Path Analysis
ERIC Educational Resources Information Center
Zhang, Haomin
2016-01-01
The present study tested a path diagram regarding the contribution of morphological awareness (MA) to early literacy acquisition among Chinese-speaking second graders (N = 123). Three facets of MA were addressed, namely derivational awareness, compound awareness and compound structure awareness. The model aimed to test a theory of causal order…
Knowledge Monitoring, Goal Orientations, Self-Efficacy, and Academic Performance: A Path Analysis
ERIC Educational Resources Information Center
Al-Harthy, Ibrahim S.; Was, Christopher A.
2013-01-01
The purpose of this study was to examine the relationship between knowledge monitoring and motivation as defined by self-efficacy and goal orientations. A path model was proposed to hypothesize the causal relations among predictors of the students' total score in the Educational Psychology course. The sample consisted of undergraduate students…
ERIC Educational Resources Information Center
Ritzhaupt, Albert D.; Dawson, Kara; Cavanaugh, Cathy
2012-01-01
The purpose of this research was to examine the effects of teachers' characteristics, school characteristics, and contextual characteristics on classroom technology integration and teacher use of technology as mediators of student use of technology. A research-based path model was designed and tested based on data gathered from 732 teachers from…
Numerical analysis of the crack growth path in the cement mantle of the reconstructed acetabulum.
Benbarek, Smaïl; Bachir Bouiadjra, Bel Abbes; El Mokhtar, Bouziane Mohamed; Achour, Tarik; Serier, Boualem
2013-01-01
In this study, we use the finite element method to analyze the propagation's path of the crack in the orthopedic cement of the total hip replacement. In fact, a small python statement was incorporated with the Abaqus software to do in loop the following operations: extracting the crack propagation direction from the previous study using the maximal circumferential stresses criterion, drawing the new path, meshing and calculating again (stresses and fracture parameters). The loop is broken when the user's desired crack length is reached (number of propagations) or the value of the mode I stress intensity factor is negative. Results show that the crack propagation's path can be influenced by human body posture. The existing of a cavity in the vicinity of the crack can change its propagation path or can absolutely attract it enough to meet it. Crack can propagate in the outward direction (toward the acetabulum bone) and cannot propagate in the opposite direction, the mode I stress intensity factor increases with the crack length and that of mode II vanishes.
Morphological Awareness in Literacy Acquisition of Chinese Second Graders: A Path Analysis
ERIC Educational Resources Information Center
Zhang, Haomin
2016-01-01
The present study tested a path diagram regarding the contribution of morphological awareness (MA) to early literacy acquisition among Chinese-speaking second graders (N = 123). Three facets of MA were addressed, namely derivational awareness, compound awareness and compound structure awareness. The model aimed to test a theory of causal order…
Knowledge Monitoring, Goal Orientations, Self-Efficacy, and Academic Performance: A Path Analysis
ERIC Educational Resources Information Center
Al-Harthy, Ibrahim S.; Was, Christopher A.
2013-01-01
The purpose of this study was to examine the relationship between knowledge monitoring and motivation as defined by self-efficacy and goal orientations. A path model was proposed to hypothesize the causal relations among predictors of the students' total score in the Educational Psychology course. The sample consisted of undergraduate students…
ERIC Educational Resources Information Center
Ritzhaupt, Albert D.; Dawson, Kara; Cavanaugh, Cathy
2012-01-01
The purpose of this research was to examine the effects of teachers' characteristics, school characteristics, and contextual characteristics on classroom technology integration and teacher use of technology as mediators of student use of technology. A research-based path model was designed and tested based on data gathered from 732 teachers from…
Feasibility Analysis of Improving On-Campus Learning Paths via a Depth Sensor
ERIC Educational Resources Information Center
Pan, Wen-Fu; Tu, Shih-Chun; Chien, Mei-Ying
2014-01-01
This research aims to apply a depth sensor to create a human-body-sensing context for outdoor learning paths; it is conducted by incorporating both quasi-experiment and survey to compare students' cognitive learning outcome within the context and understand students' attitudes toward the context created. The result of ANCOVA indicates that the…
Path Analysis on Educational Fiscal Decision-Making Mechanism in China
ERIC Educational Resources Information Center
Zhao, Hongbin; Sun, Baicai
2007-01-01
In China's current educational fiscal decision making, problems are as follows: no law to trust or not abiding by available laws, absence of equity and efficiency, as well as the standardization of decision-making procedures. It is necessary to set up effective fiscal decision-making mechanism in education and rationally devise reliable paths.
Path Analysis on Educational Fiscal Decision-Making Mechanism in China
ERIC Educational Resources Information Center
Zhao, Hongbin; Sun, Baicai
2007-01-01
In China's current educational fiscal decision making, problems are as follows: no law to trust or not abiding by available laws, absence of equity and efficiency, as well as the standardization of decision-making procedures. It is necessary to set up effective fiscal decision-making mechanism in education and rationally devise reliable paths.
Benchmark 1 - Nonlinear strain path forming limit of a reverse draw: Part C: Benchmark analysis
NASA Astrophysics Data System (ADS)
Wu, Xin
2013-12-01
This document summarizes the Benchmark 1 results and presents all submitted FEA results from 9 participants and experimental results in 104 figures, including load-displacement curves, strain path evolutions over four specified blank positions, and deformed under different forming settings: three sheet materials, three blank geometries (width), and two shim heights that alter the strain paths and the two stage strain ratio with major strain path changes. The fourth specified point corresponds to the location of localized necking. The FEA models and software/hardware used by the participants are provided. The rich data presented from both simulation and experimental measurement provide valuable information on the current interest in material plasticity/formability and their prediction under continuous non-linear strain path that exist in this reverse draw process. At the request of the author, and Proceedings Editor, a corrected and updated version of this paper was published on January 2, 2014. The Corrigendum attached to the updated article PDF contains a list of the changes made to the original published version.
ERIC Educational Resources Information Center
Lund, Stefan
2008-01-01
Decentralisation policy in Sweden emphasises school capitation allowance, the local upper secondary schools' decision-making and pupils' choices in contrast to previous bureaucratic governing. The aim of this article is to discuss how pupils' educational choice paths are a part of the different kinds of integration and differentiation processes…
Bagli, Stefano; Geneletti, Davide; Orsi, Francesco
2011-04-15
Least-cost path analysis (LCPA) allows designers to find the 'cheapest' way to connect two locations within a cost surface, which can be computed by combining multiple criteria, and therefore by accounting for different issues (environmental impact, economic investment, etc.). This procedure can be easily implemented with modern Geographic Information System (GIS) technologies, and consequently it has been widely employed to support planning and design of different types of linear infrastructures, ranging from roads to pipelines. This paper presents an approach based on the integration of multicriteria evaluation (MCE) and LCPA to identify the most suitable route for a 132 kV power line. Criteria such as cost, visibility, population density, and ecosystem naturalness were used for the analysis. Firstly, spatial MCE and LCPA were combined to generate cost surfaces, and to identify alternative paths. Subsequently, MCE was used to compare the alternatives, and rank them according to their overall suitability. Finally, a sensitivity analysis allowed the stability of the results to be tested and the most critical factors of the evaluation to be detected. The study found that small changes in the location of the power line start and end points can result in significantly different paths, and consequently impact levels. This suggested that planners should always consider alternative potential locations of terminals in order to identify the best path. Furthermore, it was shown that the use of different weight scenarios may help making the model adaptable to varying environmental and social contexts. The approach was tested on a real-world case study in north-eastern Italy.
Jin, Bo; Lant, Paul; Ge, Xiangyu
2005-08-20
The aerated stirred reactor (ASR) has been widely used in biochemical and wastewater treatment processes. The information describing how the activated sludge properties and operation conditions affect the hydrodynamics and mass transfer coefficient is missing in the literature. The aim of this study was to investigate the influence of flow regime, superficial gas velocity (U(G)), power consumption unit (P/V(L)), sludge loading, and apparent viscosity (mu(ap)) of activated sludge fluid on the mixing time (t(m)), gas hold-up (epsilon), and volumetric mass transfer coefficient (k(L)a) in an activated sludge aerated stirred column reactor (ASCR). The activated sludge fluid performed a non-Newtonian rheological behavior. The sludge loading significantly affected the fluid hydrodynamics and mass transfer. With an increase in the U(G) and P/V(L), the epsilon and k(L)a increased, and the t(m), decreased. The epsilon, k(L)a, and t(m), were influenced dramatically as the flow regime changed from homogeneous to heterogeneous patterns. The proposed mathematical models predicted the experimental results well under experimental conditions, indicating that the U(G), P/V(L), and mu(ap) had significant impact on the t(m), epsilon, and k(L)a. These models were able to give the t(m), epsilon, and k(L)a values with an error around +/-8%, and always less than +/-10%. Copyright 2005 Wiley Periodicals, Inc.
Return period adjustment for runoff coefficients based on analysis in undeveloped Texas watersheds
Dhakal, Nirajan; Fang, Xing; Asquith, William H.; Cleveland, Theodore G.; Thompson, David B.
2013-01-01
The rational method for peak discharge (Qp) estimation was introduced in the 1880s. The runoff coefficient (C) is a key parameter for the rational method that has an implicit meaning of rate proportionality, and the C has been declared a function of the annual return period by various researchers. Rate-based runoff coefficients as a function of the return period, C(T), were determined for 36 undeveloped watersheds in Texas using peak discharge frequency from previously published regional regression equations and rainfall intensity frequency for return periods T of 2, 5, 10, 25, 50, and 100 years. The C(T) values and return period adjustments C(T)/C(T=10 year) determined in this study are most applicable to undeveloped watersheds. The return period adjustments determined for the Texas watersheds in this study and those extracted from prior studies of non-Texas data exceed values from well-known literature such as design manuals and textbooks. Most importantly, the return period adjustments exceed values currently recognized in Texas Department of Transportation design guidance when T>10 years.
ERIC Educational Resources Information Center
Spanier, Graham B.; Glick, Paul C.
1980-01-01
Presents a demographic analysis of the paths to remarriage--the extent and timing of remarriage, social factors associated with remarriage, and the impact of the event which preceded remarriage (divorce or widowhood). (Author)
a Latent Variable Path Analysis Model of Secondary Physics Enrollments in New York State.
NASA Astrophysics Data System (ADS)
Sobolewski, Stanley John
The Percentage of Enrollment in Physics (PEP) at the secondary level nationally has been approximately 20% for the past few decades. For a more scientifically literate citizenry as well as specialists to continue scientific research and development, it is desirable that more students enroll in physics. Some of the predictor variables for physics enrollment and physics achievement that have been identified previously includes a community's socioeconomic status, the availability of physics, the sex of the student, the curriculum, as well as teacher and student data. This study isolated and identified predictor variables for PEP of secondary schools in New York. Data gathered by the State Education Department for the 1990-1991 school year was used. The source of this data included surveys completed by teachers and administrators on student characteristics and school facilities. A data analysis similar to that done by Bryant (1974) was conducted to determine if the relationships between a set of predictor variables related to physics enrollment had changed in the past 20 years. Variables which were isolated included: community, facilities, teacher experience, number of type of science courses, school size and school science facilities. When these variables were isolated, latent variable path diagrams were proposed and verified by the Linear Structural Relations computer modeling program (LISREL). These diagrams differed from those developed by Bryant in that there were more manifest variables used which included achievement scores in the form of Regents exam results. Two criterion variables were used, percentage of students enrolled in physics (PEP) and percent of students enrolled passing the Regents physics exam (PPP). The first model treated school and community level variables as exogenous while the second model treated only the community level variables as exogenous. The goodness of fit indices for the models was 0.77 for the first model and 0.83 for the second
NASA Astrophysics Data System (ADS)
Thomas, J. B.; Bodnar, R. J.; Shimizu, N.; Sinha, A. K.
2002-09-01
Partition coefficients ( zircon/meltD M) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that D REE increase in compatibility with increasing atomic number, similar to results of previous studies. However, D REE determined using the MIM technique are, in general, lower than previously reported values. Calculated D REE indicate that light REE with atomic numbers less than Sm are incompatible in zircon and become more incompatible with decreasing atomic number. This behavior is in contrast to most previously published results which indicate D > 1 and define a flat partitioning pattern for elements from La through Sm. The partition coefficients for the heavy REE determined using the MIM technique are lower than previously published results by factors of ≈15 to 20 but follow a similar trend. These differences are thought to reflect the effects of mineral and/or glass contaminants in samples from earlier studies which employed bulk analysis techniques. D REE determined using the MIM technique agree well with values predicted using the equations of Brice (1975), which are based on the size and elasticity of crystallographic sites. The presence of Ce 4+ in the melt results in elevated D Ce compared to neighboring REE due to the similar valence and size of Ce 4+ and Zr 4+. Predicted zircon/meltD values for Ce 4+ and Ce 3+ indicate that the Ce 4+/Ce 3+ ratios of the melt ranged from about 10 -3 to 10 -2. Partition coefficients for other trace elements determined in this study increase in compatibility in the order Ba < Rb < B < Sr < Ti < Y < Nb, with Ba, Rb, B and Sr showing incompatible behavior (D M < 1.0), and Ti, Y and Nb showing compatible behavior (D M > 1.0). The effect of partition coefficients on melt evolution during
NASA Technical Reports Server (NTRS)
Kyser, A. C.
1977-01-01
Results are presented from an elementary analysis of the effect of sweep angle on the idealized structural weight of swept wings, with cruise Mach number M and lift coefficient C sub L as parameters. The analysis indicates that sweep is unnecessary for cruise Mach numbers below about 0.80, whereas for the higher subsonic speeds, a well defined minimum-weight condition exists at a sweep angle in the neighborhood of 35 deg or 40 deg, depending on M and C sub L. The results further indicate that wing-structure weight increases sharply with Mach number in the high subsonic range, with Mach 0.85 wings weighing half again as much as Mach 0.75 wings. Weight is also shown to increase with cruise lift coefficient, but the effect is not strong for the usual range of design lift coefficients. Minimum wing-structure weight is found to occur at a ratio of thickness to normal chord of about 18 percent, but it is concluded that the thickness ratio for optimum wing design would probably lie in the range of 12 to 15 percent.
The use of the coefficient of variation in detecting sincerity of effort: a meta-analysis.
Shechtman, Orit; Anton, Stephen D; Kanasky, William F; Robinson, Michael E
2006-01-01
The coefficient of variation (CV) is used to determine sincerity of effort of strength measurements. However, there is a controversy in the literature concerning its validity and effectiveness. We used a meta-analytic approach and calculated the effect size between maximal and submaximal efforts for the CV of grip, elbow flexion and knee extension. We summarized findings concerning stability, sensitivity and specificity of the CV. We found large effect sizes (d > or = 0.8) for all comparisons indicating that submaximal efforts were more variable than maximal efforts. We also found large error rates and low stability of the CV. The error rates and stability values of the CV are unacceptable from both a clinical and a medico-legal standpoint. Therefore, the use of the CV for assessing sincerity of effort needs to be questioned.
NASA Astrophysics Data System (ADS)
Lee, Haw-Long; Chang, Win-Jin; Chen, Wen-Lih; Yang, Yu-Ching
2012-06-01
This paper numerically investigates the hyperbolic thermoelastic problem of an annular fin. The ambient convection heat transfer coefficient of the fin is assumed to be spatially varying. The major difficulty in dealing with such problems is the suppression of numerical oscillations in the vicinity of a jump discontinuity. An efficient numerical scheme involving hybrid application of Laplace transform and control volume method in conjunction with hyperbolic shape functions is used to solve the linear hyperbolic heat conduction equation. The transformed nodal temperatures are inverted to the physical quantities by using numerical inversion of the Laplace transform. Then the stress distributions in the annular fin are calculated subsequently. The results in the illustrated examples show that the application of hyperbolic shape functions can successfully suppress the numerical oscillations in the vicinity of jump discontinuities.
Evaporation in relation to CO 2 concentration: Analysis of mass transfer coefficient
NASA Astrophysics Data System (ADS)
Ojha, C. S. P.; Yasuda, Hiroshi; Rao, Surampalli; Abd Elbasit, Mohamed A. M.; Kumar, Manoj
2011-11-01
In this study, the potential of mass transfer approach in estimating evaporation changes under different CO 2 levels are evaluated using data from controlled chamber experiments in which radiation and wind velocity were kept constant and temperature and relative humidity profiles were varied in different patterns along with CO 2 concentration. Currently, FAO procedure lists three approaches to compute air vapour pressure based on temperature and relative humidity profiles. In this study, the impact of using different procedures of estimating air vapour pressure is examined to assess the use of mass transfer approach for estimating evaporation. To achieve this, a part of the data is used to calibrate mass transfer coefficient which is subsequently used to project evaporation for future states. Accordingly, strategies are ranked for their potential in estimating evaporation. The effect of evaporation rate is compared at 400 ppm and 600 ppm CO 2 level. It has been observed that the evaporation rate is more pronounced at higher CO 2 level.
Analysis of rain fade duration models for Earth-to-satellite path based on data measured in Malaysia
NASA Astrophysics Data System (ADS)
Dao, Hassan; Rafiqul, Islam Md; Al-Khateeb, Khalid A. S.
2013-12-01
Statistical analysis of rain fade duration is crucial information for system engineer to design and plan a fade mitigation technique (FMT) for the satellite communication system. An investigation is carried out based on data measured of one year period in Kuala Lumpur, Malaysia from satellite path of MEASAT3. This paper presents statistical analysis of measured fade duration on high elevation angle (77.4°) in Ku-band compared to three prediction models of fade duration. It is found that none of the models could predict measured fade duration distribution accurately.
NASA Astrophysics Data System (ADS)
Jacob, Anaïs; Mehmanparast, Ali
2016-07-01
The effects of microstructure, grain and grain boundary (GB) properties on predicted damage paths and indicative crack propagation direction have been examined for a polycrystalline material using mesoscale finite element simulations. Numerical analyses were carried out on a compact tension specimen geometry containing granular mesh structures with random grain shapes and sizes of average diameter 100μm. Nanoindentation tests were performed to investigate the dependency of mesoscale hardness measurements on the indentation location with respect to grain and GB regions. Finite element results have shown that under tensile loading conditions, the predicted damage paths are very sensitive to the granular mesh structure, GB properties and individual grain properties. Furthermore, finite element results have revealed that the cracking mode (i.e., transgranular/intergranular) and maximum crack deviation angle are strongly dependent on the material microstructures employed in simulations.
Analysis and Simulation for a Spotlight-Mode Aircraft SAR in Circular Flight Path
NASA Technical Reports Server (NTRS)
Jin, Michael Y.; Chen, Ming
1993-01-01
A wide azimuth beam SAR can offer higher resolution or wider azimuth viewing angle; two factors that help better characterize the backscattering property of targets for various science applications. One disadvantage of wide beam SAR is that a much higher pulse repetition frequency (PRF) is usually required since PRF is proportional to the radar beam angle. This problem can be resolved using a spotlight-mode concept: steering a narrow beam SAR to a fixed spot on the ground. The drawback of a spotlight-mode SAR is its limited coverage. A conventional spotlight-mode SAR operates along a straight line path as shown in Figure 1. It can be shown that spotlight-mode SAR that follows a straight line path has difficulty in achieving the ultimate resolution of lambda/4. It also cannot utilize the full 180 degree of azimuth viewing angle that can be attained only when the synthetic aperture length approaches infinity.
Watanabe, Kazuhiro; Otsuka, Yasumasa; Inoue, Akiomi; Sakurai, Kenji; Ui, Akiko; Nakata, Akinori
2016-08-01
Physical inactivity is one of the major risk factors for dyslipidemia and coronary heart disease. Job resources have been identified as determinants of employees' vigor and physical activity habits. Our first purpose was to comprehensively analyze the series of relationships of job resources, through vigor and exercise habit (i.e., one aspect of physical activity), to serum lipid levels in a sample of Japanese employees in a manufacturing company. Our second purpose was to investigate sex differences in these relationships using a multiple-group path analysis. Data were collected from 4543 employees (men = 4018, women = 525) during a medical checkup conducted in February and March 2012. Job resources (job control, skill utilization, suitable jobs, and meaningfulness of work), vigor, exercise habit, triglyceride, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured cross-sectionally. Job resources and vigor were positively associated with exercise habit in both sexes. Exercise habit was inversely associated with triglyceride (-0.03 in men and -0.01 in women, ps < 0.05) and LDL-C (-0.07 in both sexes, ps < 0.05). HDL-C was positively associated with exercise habit (0.03 in both sexes, ps < 0.05). There was no significant difference by sex in path coefficients, except for the covariance between suitable jobs and meaningfulness of work. Higher levels of job resources were associated with greater vigor, leading to exercise habit, which in turn, improved serum lipid levels. Longitudinal studies are required to demonstrate causality.
Standardized Regression Coefficients as Indices of Effect Sizes in Meta-Analysis
ERIC Educational Resources Information Center
Kim, Rae Seon
2011-01-01
When conducting a meta-analysis, it is common to find many collected studies that report regression analyses, because multiple regression analysis is widely used in many fields. Meta-analysis uses effect sizes drawn from individual studies as a means of synthesizing a collection of results. However, indices of effect size from regression analyses…
Standardized Regression Coefficients as Indices of Effect Sizes in Meta-Analysis
ERIC Educational Resources Information Center
Kim, Rae Seon
2011-01-01
When conducting a meta-analysis, it is common to find many collected studies that report regression analyses, because multiple regression analysis is widely used in many fields. Meta-analysis uses effect sizes drawn from individual studies as a means of synthesizing a collection of results. However, indices of effect size from regression analyses…
NASA Astrophysics Data System (ADS)
Quan, Xiangyu; Moriyama, Asuka; Kouichi, Nitta; Matoba, Osamu; Awatsuji, Yasuhiro
2017-04-01
This paper provides overall analytical insights on the common-path incoherent digital holography using dual-focusing lens with diffraction gratings. Especially when one tries to seek an off-axis solution using the suggested configuration, the low temporal and spatial coherence require specific conditions on parameters of the set-up. AA mathematical explanation on the off-axis digital holography is described.
Path loss analysis in millimeter wave cellular systems for urban mobile communications
NASA Astrophysics Data System (ADS)
Rajagopalan, Ramesh; Hoffman, Mitchell
2016-09-01
The proliferation in the number of mobile devices and developments in cellular technology has led to an ever increasing demand for mobile data. The global bandwidth shortage facing wireless carriers today has motivated research for fifth generation (5G) cellular systems. In recent years, millimeter wave (mmW) frequencies between 30 and 300 GHz are being considered as a promising technology for 5G systems. Such systems can offer superior user experience by providing data rates that exceed one Gigabit per second and latencies lower than a millisecond. However, there is little research about cellular mmW propagation in densely populated urban environments. Understanding the radio channel is a primary requirement for optimal design of mmW systems. Radio propagation in mmW systems faces significant challenges due to rapidly varying channel conditions and intermittent connectivity. In this paper, we study the propagation of mmW spectrum in an urban environment. We use a statistical model to simulate an urban environment with diverse building distributions. We perform extensive simulations to analyze the path loss behavior for both line of sight (LOS) and non line of sight (NLOS) conditions for 28 GHZ and 73 GHZ mmW frequencies. We observe that the path loss approximates a logarithmic fit for both LOS and NLOS environments. Our simulations show that the omnidirectional free space path loss is approximately 30 dB higher for mmW systems compared to current 3G PP cellular systems. To address this challenge, we propose using highly directional horn antennas with beam forming for reducing the path loss.
Levant, Ronald F; Stefanov, Dimitre G; Rankin, Thomas J; Halter, Margaret J; Mellinger, Chris; Williams, Christine M
2013-07-01
This study tested a theoretical model of one mediator and 4 moderators of the relationships between 2 masculinity variables (Traditional Masculinity Ideology and Gender Role Conflict) and Attitudes Toward Seeking Professional Psychological Services (Attitudes). Self-stigma was the hypothesized mediator, and the hypothesized moderators were (a) Depression, (b) General Self-efficacy, (c) Precontemplation, and (d) Barriers to Help-seeking. A sample of 654 men responded to an online survey of 9 questionnaires. After evaluating mediation in the absence of moderation, moderated path analyses were conducted for each moderator. The relationship between Traditional Masculinity Ideology and Attitudes was partially mediated by Self-stigma, whereas that between Gender Role Conflict and Attitudes was completely mediated. No indirect or direct paths involving Gender Role Conflict were moderated by any moderators. Both Depression and Barriers to Help-seeking demonstrated mediated moderation by moderating both Stage 1 (the path from Traditional Masculinity Ideology to Self-stigma) of the mediated relationships and the direct effects between Traditional Masculinity Ideology and Attitudes. Precontemplation moderated the direct effect between Traditional Masculinity Ideology and Attitudes. The findings suggest that the relationships between masculinity variables and men's negative help-seeking attitudes may be better understood through their relationships with other variables that serve as mediators and moderators. Findings from the present study may offer some direction in the design of interventions to remediate men's negative help-seeking attitudes. PsycINFO Database Record (c) 2013 APA, all rights reserved.
NASA Technical Reports Server (NTRS)
Campbell, R. H.; Kolstad, R. B.; Holle, D. F.; Miller, T. J.; Krause, P.; Horton, K.; Macke, T.
1983-01-01
Path Pascal is high-level experimental programming language based on PASCAL, which incorporates extensions for systems and real-time programming. Pascal is extended to treat real-time concurrent systems.
NASA Technical Reports Server (NTRS)
Campbell, R. H.; Kolstad, R. B.; Holle, D. F.; Miller, T. J.; Krause, P.; Horton, K.; Macke, T.
1983-01-01
Path Pascal is high-level experimental programming language based on PASCAL, which incorporates extensions for systems and real-time programming. Pascal is extended to treat real-time concurrent systems.
[Influencing factors in measuring absorption coefficient of suspended particulate matters].
Yu, Xiao-long; Shen, Fang; Zhang, Jin-fang
2013-05-01
Absorption coefficient of suspended particulate matters in natural water is one of the key parameters in ocean color remote sensing. In order to study the influencing factors that affect the measurement, a series of experiments were designed to measure samples using transmittance method (T method), transmittance-reflectance method (T-R method) and absorptance method (A method). The results shows that absorption coefficient measured by the A method has a much lower error compared to the T method and T-R method due to influencing factors,such as filter-to-filter variations, water content of the filter, and homogeneity of filter load and so on. Another factor influence absorption coefficient is path-length amplification induced by multiple scattering inside the filter. To determine the path-length amplification, the true absorption was measured by AC-s (WetLabs). The linear fitting result shows that the mean path-length amplification is much higher for the A method than that of the T-R method and the T method (4.01 versus 2.20 and 2.32), and the corresponding correlation coefficient are 0.90, 0.87 and 0.80. For the A method and the T-R method, higher correlation coefficients are calculated when using polynomial fitting, and the value are 0.95 and 0.94. Analysis of the mean relative error caused by different influencing factors indicates that path-length amplification is the largest error source in measuring the absorption coefficient.
NASA Astrophysics Data System (ADS)
Amirataee, Babak; Montaseri, Majid; Sanikhani, Hadi
2016-10-01
Reference evapotranspiration (ET0) is considered a key parameter for evaluating the climatic changes as well as spatial and temporal patterns of parameters influencing the eco-hydrological processes. The analysis of trend variations of this index can be used to determine appropriate strategies in planning and management of water resources. In this paper, the trend variations of monthly and annual ET0 in Urmia Lake basin, located in the northwest of Iran, have been analyzed using data from 14 synoptic stations in the study area. Regarding the significant effect of autocorrelation coefficients with different lags on trend variations of ET0, this paper has resorted to modified Mann-Kendall test via eliminating the significance effect of autocorrelation coefficients with different lags to analyze the trend variations. Furthermore, Theil-Sen estimator has been used to determine the slope of trend line of ET0. The results indicated an increasing trend in ET0 values at all the studied stations. Having used the modified Mann-Kendall test, the values of significant increasing (positive) trend, which were estimated using common Mann-Kendall test, dramatically decreased. As such, the values of only 7 stations have been significant at 95 % level. The results confirmed the need for eliminating the significance effect of autocorrelation coefficients with different lags to determine and evaluate the trend of hydrological variables.
Deformation analysis of amorphous metals based on atomic elastic stiffness coefficients
NASA Astrophysics Data System (ADS)
Yashiro, K.; Nishimura, M.; Tomita, Y.
2006-06-01
The elastic limit of a crystal can be evaluated by the positiveness of elastic stiffness coefficients, Bijkl. We had demonstrated that the nucleation of lattice defects such as dislocation and cleavage cracking can be predicted by the atomic Bijkl at each atom point. Amorphous metals and bulk metallic glasses draw intense interest whether the criteria are applicable or not since they are regarded as the ultimate of lattice defects. In the present study, an amorphous Ni-Al binary alloy is made by a usual melt-quench simulation and subjected to tension by means of molecular dynamics simulation. During simulations, the positiveness of atomic Bijkl is discussed for all atoms. Contrary to an Ni-Al crystal, many atoms show negative value even in the initial equilibrium of the amorphous before loading. These unstable atoms turn out to be the non-clustered atom or the outer-shell of the local cluster such as 12(0, 0, 12, 0) icosahedron. On the other hand, the centre atoms of the local clusters show high stability resulting in the positive Bijkl of the whole system. It is also demonstrated that the change in the atomic Bijkl can reveal the collapse and re-configuration of local clusters during the deformation.
NASA Astrophysics Data System (ADS)
Bricaud, Annick; Babin, Marcel; Morel, André; Claustre, Hervé
1995-07-01
Variability in the chlorophyll (chl) a-specific absorption coefficients of living phytoplankton aph*(λ) was analyzed using a data set including 815 spectra determined with the wet filter technique in different regions of the world ocean (covering the chlorophyll concentration range 0.02-25 mg m-3). The aph* values were observed to decrease rather regularly from oligotrophic to eutrophic waters, spanning over more than 1 order of magnitude (0.18 to 0.01 m2 mg-1) at the blue absorption maximum. The observed covariation between aph*(λ) and the field chl a concentration (chl) can be explained considering (1) the level or pigment packaging and (2) the contribution of accessory pigments to absorption. Empirical relationships between aph*(λ) and
A meta-analysis of the canopy light extinction coefficient in terrestrial ecosystems
NASA Astrophysics Data System (ADS)
Zhang, Liangxia; Hu, Zhongmin; Fan, Jiangwen; Zhou, Decheng; Tang, Fengpei
2014-12-01
The canopy light extinction coefficient ( K) is a key factor in affecting ecosystem carbon, water, and energy processes. However, K is assumed as a constant in most biogeochemical models owing to lack of in-site measurements at diverse terrestrial ecosystems. In this study, by compiling data of K measured at 88 terrestrial ecosystems, we investigated the spatiotemporal variations of this index across main ecosystem types, including grassland, cropland, shrubland, broadleaf forest, and needleleaf forest. Our results indicated that the average K of all biome types during whole growing season was 0.56. However, this value in the peak growing season was 0.49, indicating a certain degree of seasonal variation. In addition, large variations in K exist within and among the plant functional types. Cropland had the highest value of K (0.62), followed by broadleaf forest (0.59), shrubland (0.56), grassland (0.50), and needleleaf forest (0.45). No significant spatial correlation was found between K and the major environmental factors, i.e., mean annual precipitation, mean annual temperature, and leaf area index (LAI). Intra-annually, significant negative correlations between K and seasonal changes in LAI were found in the natural ecosystems. In cropland, however, the temporal relationship was site-specific. The ecosystem type specific values of K and its temporal relationship with LAI observed in this study may contribute to improved modeling of global biogeochemical cycles.
Wavelet coefficient analysis for the quantitative determination of damage in tendons and cables
NASA Astrophysics Data System (ADS)
Rizzo, Piervincenzo; Lanza di Scalea, Francesco
2005-05-01
Wires, bars, multi-wire strands made of steel or composite materials are widely used in civil infrastructures as tensioning members in cable-stayed bridges, suspension bridges and prestressed concrete. The health monitoring of these components is a long-standing challenge in the NDE community. In the last few years, the authors have been conducting a study on the application of ultrasonic guided waves for the structural health monitoring of bars and multi-wire strands. This paper presents an application of a signal processing technique based on the Discrete Wavelet Transform (DWT) for the detection and the quantification of damage (in the form of small notches) in loaded seven-wire steel strands. The DWT is applied to ultrasonic signals generated and detected via magnetostrictive transducers. The detection and the quantification of damage in the strands are accomplished by constructing and computing a damage index based on the variance and the root mean square of the wavelet coefficient vector of the ultrasonic damage signatures. It is shown that the logarithmic value of the damage index is linearly dependent on the damage size. In the last portion of the paper an eight-dimensional damage index is constructed and it is fed to an artificial neural network that classifies the size and the location of the notch.
Kim, Isok
2014-01-01
This study used a path analytic technique to examine associations among critical ethnic awareness, racial discrimination, social support, and depressive symptoms. Using a convenience sample from online survey of Asian American adults (N = 405), the study tested 2 main hypotheses: First, based on the empowerment theory, critical ethnic awareness would be positively associated with racial discrimination experience; and second, based on the social support deterioration model, social support would partially mediate the relationship between racial discrimination and depressive symptoms. The result of the path analysis model showed that the proposed path model was a good fit based on global fit indices, χ²(2) = 4.70, p = .10; root mean square error of approximation = 0.06; comparative fit index = 0.97; Tucker-Lewis index = 0.92; and standardized root mean square residual = 0.03. The examinations of study hypotheses demonstrated that critical ethnic awareness was directly associated (b = .11, p < .05) with the racial discrimination experience, whereas social support had a significant indirect effect (b = .48; bias-corrected 95% confidence interval [0.02, 1.26]) between the racial discrimination experience and depressive symptoms. The proposed path model illustrated that both critical ethnic awareness and social support are important mechanisms for explaining the relationship between racial discrimination and depressive symptoms among this sample of Asian Americans. This study highlights the usefulness of the critical ethnic awareness concept as a way to better understand how Asian Americans might perceive and recognize racial discrimination experiences in relation to its mental health consequences.
NASA Astrophysics Data System (ADS)
Quan, J.
2016-12-01
Near surface air temperature (Ta) is one of the most critical variables in climatology, hydrology, epidemiology and environmental health. In-situ measurements are not efficient for characterizing spatially heterogeneous Ta, while remote sensing is a powerful tool to break this limitation. This study proposes a mapping framework for daily mean Ta using an enhanced empirical regression method based on remote sensing data. It differs from previous studies in three aspects. First, nighttime light data is introduced as a predictor (besides seven most Ta-relevant variables, i.e., land surface temperature, normalized difference vegetation index, impervious surface area, black sky albedo, normalized difference water index, elevation, and duration of daylight) considering the urbanization-induced Ta increase over a large area. Second, independent components are extracted using principal component analysis considering the correlations among the above predictors. Third, a composite sinusoidal coefficient regression is developed considering the dynamic Ta-predictor relationship. The derived coefficients are then applied back to the spatially collocated predictors to reconstruct spatio-temporal Ta. This method is performed with 333 weather stations in China during the 2001-2012 period. Evaluation shows overall mean error of -0.01 K, root mean square error (RMSE) of 2.53 K, correlation coefficient (R2) of 0.96, and average uncertainty of 0.21 K. Model inter-comparison shows that this method outperforms six additional empirical regressions that have not incorporated nighttime light data or considered multi-predictor correlations or coefficient dynamics (by 0.18-2.60 K in RMSE and 0.00-0.15 in R2).
Rural out-migration in southern Manitoba: a simple path analysis of "push" factors.
Todd, D
1981-01-01
"Rural out-migration from southern Manitoba over the period 1971-76 is subjected to a path-analytic model which claims that the exodus is due to unsatisfactory economic and social conditions. In particular, the model is structured so that migration and community satisfaction both depend upon the economic standing of a community. Results indicate that while economic conditions are key factors in rural out-migration, other variables, especially those representative of rural isolation, are also of great importance. These conclusions remain tenable even after allowing for feedback effects from the rural out-migration." (summary in FRE) excerpt
NASA Technical Reports Server (NTRS)
Ko, H. C.
1973-01-01
The wave-normal emissivity and the ray emissivity formulas for an electron moving along a helical path in a magnetoactive medium are presented. Simplified formulas for the case of an isotropic plasma are also given. Because of the helical motion of the electron, a difference exists between the radiated power per unit solid angle and the received power per unit solid angle. The relation between these two quantities in a magnetoactive medium is shown. Results are compared with those obtained by others, and the sources of discrepancies are pointed out.
NASA Technical Reports Server (NTRS)
Keesler, E. L.
1974-01-01
The functional paths of the Orbital Maneuver Subsystem (OMS) is defined. The operational flight instrumentation required for performance monitoring, fault detection, and annunciation is described. The OMS is a pressure fed rocket engine propulsion subsystem. One complete OMS shares each of the two auxiliary propulsion subsystem pods with a reaction control subsystem. Each OMS is composed of a pressurization system, a propellant tanking system, and a gimbaled rocket engine. The design, development, and operation of the system are explained. Diagrams of the system are provided.
An Analysis of the Assembly Path Planning of Decelerator Based on Virtual Technology
NASA Astrophysics Data System (ADS)
Jin, Xiangyang; Zhang, Tiefeng; Yang, Hanlin
According to structural features of different components of decelerator, the general rule of three-dimensional solid modeling of components is summarized, the three-dimensional model of gear stand is built, all components are organized into groups to form a whole partial assembly, and various kinds of assembly relations are added among components, as well as hierarchical relations. Then the assembly path of decelerator is programmed, the sequence of assembling components is decided, and finally the assembly simulation is completed, laying the foundation for component disassembly. Virtual assembly technology helps to introduce advanced design approaches, improve the quality of products, reduce development cost and shorten development cycle.
NASA Astrophysics Data System (ADS)
Rogal, Jutta; Lechner, Wolfgang; Juraszek, Jarek; Ensing, Bernd; Bolhuis, Peter G.
2010-11-01
We introduce a reweighting scheme for the path ensembles in the transition interface sampling framework. The reweighting allows for the analysis of free energy landscapes and committor projections in any collective variable space. We illustrate the reweighting scheme on a two dimensional potential with a nonlinear reaction coordinate and on a more realistic simulation of the Trp-cage folding process. We suggest that the reweighted path ensemble can be used to optimize possible nonlinear reaction coordinates.
NASA Technical Reports Server (NTRS)
Taylor, C. M.
1977-01-01
A ceramic/metallic aircraft gas turbine outer gas path seal designed to enable improved engine performance is studied. Flexible numerical analysis schemes suitable for the determination of transient temperature profiles and thermal stress distributions in the seal are outlined. An estimation of the stresses to which a test seal is subjected during simulated engine deceleration from sea level takeoff to idle conditions is made. Experimental evidence has indicated that the surface layer of the seal is probably subjected to excessive tensile stresses during cyclic temperature loading. This assertion is supported by the analytical results presented. Brief consideration is given to means of mitigating this adverse stressing.
ERIC Educational Resources Information Center
Dolan, Conor V.; Wicherts, Jelte M.; Molenaar, Peter C. M.
2004-01-01
We consider the question of how variation in the number and reliability of indicators affects the power to reject the hypothesis that the regression coefficients are zero in latent linear regression analysis. We show that power remains constant as long as the coefficient of determination remains unchanged. Any increase in the number of indicators…
Eggleston, Gillian; Yen, Jenny Wu Tiu; Alexander, Clay; Gober, Jessica
2012-07-01
Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial metabolism of sucrose and fructose from both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (K(eff)) between impure sucrose syrup and crystal has been investigated in a batch laboratory crystallizer and a batch pilot plant-scale vacuum pan. Laboratory crystallization was operated at 65.5°C (150°F), 60.0°C (140°F), and 51.7°C (125°F) with a 78.0 Brix (% refractometric dissolved solids) pure sucrose syrup containing 0%, 0.1%, 0.2%, 1.0%, 2.0%, 3.0%, and 10% (at 65.5°C only) mannitol on a Brix basis. Produced mother liquor and crystals were separated by centrifugation and their mannitol contents measured by ion chromatography with integrated pulsed amperometric detection (IC-IPAD). The extent of mannitol partitioning into the crystals depended strongly on the mannitol concentration in the feed syrup and, to a lesser extent, the crystallization temperature. At 65.5 and 60.0°C, the K(eff) varied from ~0.4% to 3.0% with 0.2% to 3.0% mannitol in the feed syrup, respectively. The mannitol K(eff) was lower than that reported for dextran (~9-10% K(eff)), another product of Leuconstoc deterioration, under similar sucrose crystal growth conditions. At 10% mannitol concentration in the syrup at 65.5°C, co-crystallization of mannitol with sucrose occurred and the crystal growth rate was greatly impeded. In both laboratory and pilot plant crystallizations (95.7% purity; 78.0 Brix; 65.5°C), mannitol tended to cause conglomerates to form, which became progressively worse with increased mannitol syrup concentration. At the 3% mannitol concentration, crystallization at both the laboratory and pilot plant scales was more difficult. Mannitol incorporation into the sucrose crystal results mostly from liquid syrup inclusions but adsorption onto the crystal surface may play a minor role at lower mannitol concentrations.
Advanced Launch System Multi-Path Redundant Avionics Architecture Analysis and Characterization
NASA Technical Reports Server (NTRS)
Baker, Robert L.
1993-01-01
The objective of the Multi-Path Redundant Avionics Suite (MPRAS) program is the development of a set of avionic architectural modules which will be applicable to the family of launch vehicles required to support the Advanced Launch System (ALS). To enable ALS cost/performance requirements to be met, the MPRAS must support autonomy, maintenance, and testability capabilities which exceed those present in conventional launch vehicles. The multi-path redundant or fault tolerance characteristics of the MPRAS are necessary to offset a reduction in avionics reliability due to the increased complexity needed to support these new cost reduction and performance capabilities and to meet avionics reliability requirements which will provide cost-effective reductions in overall ALS recurring costs. A complex, real-time distributed computing system is needed to meet the ALS avionics system requirements. General Dynamics, Boeing Aerospace, and C.S. Draper Laboratory have proposed system architectures as candidates for the ALS MPRAS. The purpose of this document is to report the results of independent performance and reliability characterization and assessment analyses of each proposed candidate architecture and qualitative assessments of testability, maintainability, and fault tolerance mechanisms. These independent analyses were conducted as part of the MPRAS Part 2 program and were carried under NASA Langley Research Contract NAS1-17964, Task Assignment 28.
Analysis of climate paths reveals potential limitations on species range shifts.
Early, Regan; Sax, Dov F
2011-11-01
Forecasts of species endangerment under climate change usually ignore the processes by which species ranges shift. By analysing the 'climate paths' that range shifts might follow, and two key range-shift processes--dispersal and population persistence--we show that short-term climatic and population characteristics have dramatic effects on range-shift forecasts. By employing this approach with 15 amphibian species in the western USA, we make unexpected predictions. First, inter-decadal variability in climate change can prevent range shifts by causing gaps in climate paths, even in the absence of geographic barriers. Second, the hitherto unappreciated trait of persistence during unfavourable climatic conditions is critical to species range shifts. Third, climatic fluctuations and low persistence could lead to endangerment even if the future potential range size is large. These considerations may render habitat corridors ineffectual for some species, and conservationists may need to consider managed relocation and augmentation of in situ populations. © 2011 Blackwell Publishing Ltd/CNRS.
Sanagi, Mohd Marsin; Miskam, Mazidatulakmam; Wan Ibrahim, Wan Aini; Hermawan, Dadan; Aboul-Enein, Hassan Y
2010-07-01
A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.
NASA Astrophysics Data System (ADS)
Lathabai, Hiran H.; Prabhakaran, Thara; Changat, Manoj
2015-07-01
Biotechnology, ever since its inception has had a huge impact on the society and its various applications have been intricately woven into the human web of life. Its evolution amidst all the other research realms vital to mankind is remarkable. In this paper, we intend to identify the radical innovations in Biotechnology for Engineering using network analyses. Centrality analysis and Path analysis are used for identifying important works. Existence of Flow Vergence effect in the scientific literature is revealed. Flow Vergence gradient, an arc metric derived from FV model, is utilised for Path analysis which detects pivotal papers of paradigm shift more accurately. A major paradigm shift has been identified in the business models of Biotechnology for Engineering - 'Capability to Connectivity' model. Evidence towards the adoption of business practices in BT firms by nanotechnology start-ups is also identified. The notion of critical divergence is introduced and the exhibition of interdisciplinary interaction in emerging fields due to critical divergence is discussed. Implications of above analyses which target: (i) Science and technology policy makers, (ii) industrialists and investors, (iii) researchers in academia as well as industry, are also discussed.
The impact of photon flight path on S1 pulse shape analysis in liquid xenon two-phase detectors
NASA Astrophysics Data System (ADS)
Moongweluwan, M.
2016-02-01
The LUX dark matter search experiment is a 350 kg dual-phase xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. The success of two-phase xenon detectors for dark matter searches relies on their ability to distinguish electron recoil (ER) background events from nuclear recoil (NR) signal events. Typically, the NR-ER discrimination is obtained from the ratio of the electroluminescence light (S2) to the prompt scintillation light (S1). Analysis of the S1 pulse shape is an additional discrimination technique that can be used to distinguish NR from ER. Pulse-shape NR-ER discrimination can be achieved based on the ratio of the de-excitation processes from singlet and triplet states that generate the S1. The NR S1 is dominated by the de-excitation process from singlet states with a time constant of about 3 ns while the ER S1 is dominated by the de-excitation process from triplet states with a time constant of about 24 ns. As the size of the detectors increases, the variation in the S1 photon flight path can become comparable to these decay constants, reducing the utility of pulse-shape analysis to separate NR from ER. The effect of path length variations in the LUX detector has been studied using the results of simulations and the impact on the S1 pulse shape analysis is discussed.
Kordaß, Bernd; Ruge, Sebastian
2015-01-01
Analysis of temporomandibular joint (TMJ) function using condylar path tracings is a challenge in functionally oriented dentistry. In most cases, reference points on the skin surface over the TMJ region are defined as "arbitrary", "individual" or "kinematic" condylar hinge axis points, which are displayed as "condylar paths" in motion. To what extent these reference points represent the actual condylar paths in each individual patient is ultimately unclear because the geometric relationship of the actual condyle to the selected reference point is usually unknown. Depending on the location of the point on the condyle and the centers of rotation of mandibular movement, these trajectories can vary greatly during combined rotational and sliding movements (eg, opening and closing movements of the mandible); this represents a grid of points located in the vicinity of the TMJ. To record the actual condylar path as the movement trajectory of a given point (eg, the condylar center), technological solutions are needed with which to link the tracing technology with the appropriate imaging technology capable of scanning the condyle, including the points of interest, and displaying them in real dynamic motion. Sicat Function (Sicat, D-Bonn) is such a solution. Sicat Function links cone beam computed tomography (CBCT) scans (made using the Galileos CBCT scanner; Sirona, Bensheim, Germany) with ultrasound-based, three-dimensional (3D) functional jaw movement recordings of the mandible (made using the JMT+ Jaw Motion Tracker; Sicat, Bonn, Germany). Digital images of the dental arches acquired with the intraoral scanner Cerec system (Sirona) can also be superimposed. This results in the generation of a 3D model of the bony mandible, including the TMJ, which reproduces the 3D real dynamic movement of the condyles simultaneously with that of the condylar paths at defined points (with the condylar centers being a particular point of interest). Sicat Function is an integrated, digital
Exact Analysis of Squared Cross-Validity Coefficient in Predictive Regression Models
ERIC Educational Resources Information Center
Shieh, Gwowen
2009-01-01
In regression analysis, the notion of population validity is of theoretical interest for describing the usefulness of the underlying regression model, whereas the presumably more important concept of population cross-validity represents the predictive effectiveness for the regression equation in future research. It appears that the inference…
Exact Analysis of Squared Cross-Validity Coefficient in Predictive Regression Models
ERIC Educational Resources Information Center
Shieh, Gwowen
2009-01-01
In regression analysis, the notion of population validity is of theoretical interest for describing the usefulness of the underlying regression model, whereas the presumably more important concept of population cross-validity represents the predictive effectiveness for the regression equation in future research. It appears that the inference…
NASA Astrophysics Data System (ADS)
Bhowmik, Mrinal K.; Bhattacharjee, Debotosh; Basu, Dipak K.; Nasipuri, Mita
2011-06-01
In this paper, an image fusion technique based on weighted average of Daubechies wavelet transform (db2) coefficients from visual face image and their corresponding thermal images have been presented. Further, a comparative study has been conducted for dimensionality reduction based on Principal Component Analysis (PCA) and Independent Component Analysis (ICA). Fused images thus obtained are classified using a multi-layer perceptron (MLP). For experiments IRIS Thermal/Visual Face Database has been used. Experimental results show that the performance of ICA architecture-I is better than the other two approaches i.e. PCA and ICA-II. The average success rate for PCA, ICA-I and ICA-II are 91.13%, 94.44% and 89.72% respectively. However, approaches presented here achieves maximum success rate of 100% in some cases, especially in case of varying illumination.
NASA Astrophysics Data System (ADS)
Zhou, Jianqin; Shen, Jun; Neill, W. Stuart
2016-07-01
A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry-Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy's formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes.
NASA Technical Reports Server (NTRS)
Powell, W. B.
1973-01-01
A methodology is described for the analysis of a transient temperature measurement made in a flat or curved plate subjected to convective heat transfer, such that the surface heat flux, the hot-gas temperture, and the gas heat transfer coefficient can be determined. It is shown that if the transient temperature measurement is made at a particular point located nearly midway in the thickness of the plate there is an important simplification in the data analysis process, in that the factor relating the surface heat flux to the measured rate of rise of temperature becomes invariant for a Fourier Number above 0.60 and for all values of the Biot Number. Parameters are derived, tabulated, and plotted which enable straightforward determination of the surface heat flux, the hot-gas temperature, of the plate, the rate of rise of temperature, the plate thickness and curvature, and the mean thermal properties of the plate material at the test temperature.
Ternary diffusion path in terms of eigenvalues and eigenvectors
NASA Astrophysics Data System (ADS)
Ram-Mohan, L. R.; Dayananda, Mysore A.
2016-04-01
Based on the transfer matrix methodology, a new analysis is presented for the description of slopes of the ternary diffusion path for a solid-solid diffusion couple. Concentration profiles and diffusion paths for isothermal, ternary diffusion couples are examined in the context of eigenvalues and eigenvectors obtained from the diagonalisation of the ? ternary interdiffusion coefficients employed for their representation. New relations are derived relating the decoupled interdiffusion fluxes to combinations of concentration gradients through the major and minor eigenvalues, and the diffusion path becomes parallel to the major eigenvector at each path end. General expressions for the slope of the ternary diffusion path at any section of the couple are also derived in terms of eigenvalue and eigenvector parameters. Expressions for the path slope at the Matano plane involve only concentrations, major and minor eigenvalues and eigenvector parameters. New constraints relating the eigenvalues and the concentration gradients of the individual components are also presented at selected sections, where the diffusion path is parallel to the straight line joining the terminal composition points on an isotherm. Applications of the various relations are illustrated with the aid of a hypothetical couple and an experimental Cu-Ni-Zn diffusion couple.
Point and path performance of light aircraft: A review and analysis
NASA Technical Reports Server (NTRS)
Smetana, F. O.; Summey, D. C.; Johnson, W. D.
1973-01-01
The literature on methods for predicting the performance of light aircraft is reviewed. The methods discussed in the review extend from the classical instantaneous maximum or minimum technique to techniques for generating mathematically optimum flight paths. Classical point performance techniques are shown to be adequate in many cases but their accuracies are compromised by the need to use simple lift, drag, and thrust relations in order to get closed form solutions. Also the investigation of the effect of changes in weight, altitude, configuration, etc. involves many essentially repetitive calculations. Accordingly, computer programs are provided which can fit arbitrary drag polars and power curves with very high precision and which can then use the resulting fits to compute the performance under the assumption that the aircraft is not accelerating.
Social support, stress, health, and academic success in Ghanaian adolescents: a path analysis.
Glozah, Franklin N; Pevalin, David J
2014-06-01
The aim of this study is to gain a better understanding of the role psychosocial factors play in promoting the health and academic success of adolescents. A total of 770 adolescent boys and girls in Senior High Schools were randomly selected to complete a self-report questionnaire. School reported latest terminal examination grades were used as the measure of academic success. Structural equation modelling indicated a relatively good fit to the posteriori model with four of the hypothesised paths fully supported and two partially supported. Perceived social support was negatively related to stress and predictive of health and wellbeing but not academic success. Stress was predictive of health but not academic success. Finally, health and wellbeing was able to predict academic success. These findings have policy implications regarding efforts aimed at promoting the health and wellbeing as well as the academic success of adolescents in Ghana.
Graphical and Statistical Analysis of Airplane Passenger Cabin RF Coupling Paths to Avionics
NASA Technical Reports Server (NTRS)
Jafri, Madiha; Ely, Jay; Vahala, Linda
2003-01-01
Portable wireless technology provides many benefits to modern day travelers. Over the years however, numerous reports have cited portable electronic devices (PEDs) as a possible cause of electromagnetic interference (EMI) to aircraft navigation and communication radio systems. PEDs may act as transmitters, both intentional and unintentional, and their signals may be detected by the various radio receiver antennas installed on the aircraft. Measurement of the radiated field coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas is defined herein as interference path loss (IPL). IPL data is required for assessing the threat of PEDs to aircraft radios, and is very dependent upon airplane size, the interfering transmitter position within the airplane, and the location of the particular antenna for the aircraft system of concern. NASA Langley Research Center, Eagles Wings Inc., and United Airlines personnel performed extensive IPL measurements on several Boeing 737 airplanes.
Quantum path analysis of high-order above-threshold ionization
NASA Astrophysics Data System (ADS)
Kopold, R.; Becker, W.; Kleber, M.
2000-05-01
High-order above-threshold ionization spectra are calculated via an improved Keldysh approximation that takes rescattering into account. An approximate method of evaluating the crucial multidimensional integral proceeds via the saddle point method. The saddle points define complex orbits in position space that depart from the ion and return to it to rescatter. The real parts of these orbits are very closely related to the trajectories of the simple-man model. The spectra are analyzed in terms of these quantum orbits whose constructive and destructive interferences generate the spectrum's intricate structures. In most spectral regions, the six trajectories having the shortest travel times between start and return already provide an excellent approximation to the exact calculation. In exceptional cases, more orbits are required. The quantum orbits provide an illuminating illustration of the quantum mechanical path integral.
Analysis of the spectral response of fractal antennas related with its geometry and current paths
NASA Astrophysics Data System (ADS)
Cuadrado, Alexander; López-Alonso, José M.; Martínez-Antón, Juan C.; Ezquerro, José M.; González, Francisco J.; Alda, Javier
2015-08-01
Fractal antennas have been proposed to improve the bandwidth of resonant structures and optical antennas. Their multiband characteristics are of interest in radiofrequency and microwave technologies. In this contribution we link the geometry of the current paths built-in the fractal antenna with the spectral response. We have seen that the actual currents owing through the structure are not limited to the portion of the fractal that should be geometrically linked with the signal. This fact strongly depends on the design of the fractal and how the different scales are arranged within the antenna. Some ideas involving materials that could actively respond to the incoming radiation could be of help to spectrally select the response of the multiband design.
Path analysis examining self-efficacy and decision-making performance on a simulated baseball task.
Hepler, Teri J; Feltz, Deborah L
2012-03-01
The purpose of this study was to examine the relationship between decision-making self-efficacy and decision-making performance in sport. Undergraduate students (N = 78) performzed 10 trials of a decision-making task in baseball. Self-efficacy was measured before performing each trial. Decision-making performance was assessed by decision speed and decision accuracy. Path analyses examined the relationships between self-efficacy, residualized past performance, and current performance. The results indicated that self-efficacy was a significant and consistent predictor of decision speed (eight of nine trials), but not decision accuracy (four of nine trials). It was also found that experience does not have a meaningful effect on the relationship between self-efficacy and decision-making performance in sport.
Sorority Affiliation and Sexual Assault Victimization: Assessing Vulnerability Using Path Analysis.
Franklin, Cortney A
2016-07-01
The current research used survey data from 282 college women to investigate the relationship between female Greek membership and sexual assault victimization. Drawing from routine activity theory, low self-control, and social learning theory, this study tested a theoretical model that identified pertinent factors present among sorority environments to determine the relationships between Greek affiliation and sexual assault. Path analyses revealed that sorority women reported consuming more alcohol and with greater frequency, increased risk-taking behavior, delayed assessments of threat and responses to risk, and increased contact with fraternity men-all of which significantly predicted sexual assault. Future theory, research, and policy directions are proposed. © The Author(s) 2015.
Kudi: A free open-source python library for the analysis of properties along reaction paths.
Vogt-Geisse, Stefan
2016-05-01
With increasing computational capabilities, an ever growing amount of data is generated in computational chemistry that contains a vast amount of chemically relevant information. It is therefore imperative to create new computational tools in order to process and extract this data in a sensible way. Kudi is an open source library that aids in the extraction of chemical properties from reaction paths. The straightforward structure of Kudi makes it easy to use for users and allows for effortless implementation of new capabilities, and extension to any quantum chemistry package. A use case for Kudi is shown for the tautomerization reaction of formic acid. Kudi is available free of charge at www.github.com/stvogt/kudi.
McGue, M; Rao, D C; Iselius, L; Russell, J M
1985-01-01
A path model and associated statistical method for the analysis of data on twin families are introduced and applied to high density lipoprotein cholesterol (HDL-c) observations in the Swedish Twin Family Study. The proposed path model incorporates both genetic and environmental sources of familial resemblance, maternal environmental effects, intergenerational differences in heritabilities, marital resemblance due to either primary or secondary phenotypic homogamy, and twin residual environmental correlations. Application of the model to HDL-c levels resulted in parameter estimates consistent with those reported in earlier reviews and in the analysis of nuclear family and twin data. Genetic heritability was estimated as h2 = .363 +/- .243, cultural heritability as c2 = .187 +/- .082, and the proportion of phenotypic variance due to residual environmental effects as r2 = .450 +/- .207. Although the parameter estimates were comparable, the statistical tests of hypotheses were, relative to other designs, of low statistical power. It appears that environmental indices are necessary for powerful tests of hypotheses. PMID:4050793
Gholamnia Shirvani, Zeinab; Ghofranipour, Fazlollah; Gharakhanlou, Reza; Kazemnejad, Anoshirvan
2014-11-30
Level of physical activity as a key determinant of healthy lifestyle less than is required in individuals particularly women. Applying theories of behavioral change about complex behaviors such as physical activity leads to identify effective factors and their relations. The aim of this study was to determine predictors of physical activity behavior based on the Theory of Planned Behavior in military staff's wives in Tehran. This cross-sectional study was performed in 180 military personnel's spouses residing in organizational houses, in Tehran, Iran in 2014. The participants were randomly selected with multi-stage cluster sampling. The validity and reliability of the theory based scale evaluated before conducting the path analysis. Statistical analysis was carried out using SPSS16 and LISREL8.8. The results indicated the model explained 77% and 17% of intention and behavior variance. Subjective norms (Beta=0.83) and intention (Beta=0.37) were the strongest predictors of intention and behavior, respectively. The instrumental and affective attitude had no significant path to intention and behavior. The direct relation of perceived behavioral control to behavior was non-significant. This research demonstrated relative importance and relationships of Theory of Planned Behavior constructs in physical activity behavior of military personnel's spouses in Tehran. It is essential to consider these determinants in designing of educational interventions for promoting and maintaining physical activity behavior in this target group.
NASA Technical Reports Server (NTRS)
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.
NASA Astrophysics Data System (ADS)
Huang, Xianli; Morita, Shigeru; Oishi, Tetsutarou; Murakami, Izumi; Goto, Motoshi; Zhang, Hongming; Liu, Yang
2016-10-01
With impurity pellet injection and a one-dimensional transport code, the transport of Al and Fe ions has been analyzed in the Large Helical Device (LHD) based on extreme ultraviolet (EUV) space-resolved spectroscopy. The total density of Fe ions in the plasma core has been analyzed from the radial profiles of the Fe n =3-2 Lα emissions. When the ne profile is peaked or hollow, the Fe density also exhibits a peaked or hollow profile, respectively. Fe transport analysis shows that the convective velocity (V) is outward in the plasma core and inward near the edge when the ne profile is hollow. On the other hand, the V takes negative value over the whole radial range in the peaked ne profile. Therefore, the different Fe density profiles between peaked and hollow ne profiles can be explained by the significant difference in the V profile. Comparison of the transport coefficients between Al and Fe shows the magnitude of V for Al ions seems to be smaller than that for Fe ions while the difference in the diffusion coefficient profile is not significant. The difference in the decay time of line emissions between the two speices is attributed to the weaker convection for the Al.
Analysis of ligand-protein exchange by Clustering of Ligand Diffusion Coefficient Pairs (CoLD-CoP).
Snyder, David A; Chantova, Mihaela; Chaudhry, Saadia
2015-06-01
NMR spectroscopy is a powerful tool in describing protein structures and protein activity for pharmaceutical and biochemical development. This study describes a method to determine weak binding ligands in biological systems by using hierarchic diffusion coefficient clustering of multidimensional data obtained with a 400 MHz Bruker NMR. Comparison of DOSY spectrums of ligands of the chemical library in the presence and absence of target proteins show translational diffusion rates for small molecules upon interaction with macromolecules. For weak binders such as compounds found in fragment libraries, changes in diffusion rates upon macromolecular binding are on the order of the precision of DOSY diffusion measurements, and identifying such subtle shifts in diffusion requires careful statistical analysis. The "CoLD-CoP" (Clustering of Ligand Diffusion Coefficient Pairs) method presented here uses SAHN clustering to identify protein-binders in a chemical library or even a not fully characterized metabolite mixture. We will show how DOSY NMR and the "CoLD-CoP" method complement each other in identifying the most suitable candidates for lysozyme and wheat germ acid phosphatase.
Analysis of ligand-protein exchange by Clustering of Ligand Diffusion Coefficient Pairs (CoLD-CoP)
NASA Astrophysics Data System (ADS)
Snyder, David A.; Chantova, Mihaela; Chaudhry, Saadia
2015-06-01
NMR spectroscopy is a powerful tool in describing protein structures and protein activity for pharmaceutical and biochemical development. This study describes a method to determine weak binding ligands in biological systems by using hierarchic diffusion coefficient clustering of multidimensional data obtained with a 400 MHz Bruker NMR. Comparison of DOSY spectrums of ligands of the chemical library in the presence and absence of target proteins show translational diffusion rates for small molecules upon interaction with macromolecules. For weak binders such as compounds found in fragment libraries, changes in diffusion rates upon macromolecular binding are on the order of the precision of DOSY diffusion measurements, and identifying such subtle shifts in diffusion requires careful statistical analysis. The "CoLD-CoP" (Clustering of Ligand Diffusion Coefficient Pairs) method presented here uses SAHN clustering to identify protein-binders in a chemical library or even a not fully characterized metabolite mixture. We will show how DOSY NMR and the "CoLD-CoP" method complement each other in identifying the most suitable candidates for lysozyme and wheat germ acid phosphatase.
NASA Astrophysics Data System (ADS)
Nayak, Ramesh K.; Sundarraj, Suresh
2010-02-01
Mold-metal interface heat transfer coefficient values need to be determined precisely to accurately predict thermal histories at different locations in automotive castings. Thermomechanical simulations were carried out for Al-Si alloy casting processes using a commercial code. The cooling curve results were validated with experimental data from the literature for a cylindrical-shaped casting. Our analysis indicates that the interface heat transfer coefficient (IHTC) initial value choice between chill-metal and the sand mold-metal interfaces has a marked effect on the cooling curves. In addition, after choosing an IHTC initial value, the solidification rates of the alloy near the chill-metal interfaces varied during subsequent cooling when the gap began to form. However, the gap formation, which results in an IHTC change from the initial value, does not affect the cooling curves within the vicinity of the sand-metal interface. Optimized initial IHTC values of 3000 and 7000 W m-2-K-1 were determined for a sand-metal interface and a chill (steel or copper)-metal interfaces, respectively. The initial IHTC had a significant effect on the prediction of secondary dendrite arm spacing (SDAS) (varying between approximately 15 microns and 70 microns) and ultimate tensile strength (UTS) (varying between approximately 250 MPa and 370 MPa) for initial IHTC values that were less than the optimized value of 7000 W m-2 K-1 for the chill-metal interfaces.
Santos, A. dos; Fuga, R.; Abe, A.Y.
2005-10-15
TORT, an S{sub N} three-dimensional transport code, is employed for the analysis of the inversion point of the isothermal reactivity coefficient of the IPEN/MB-01 reactor. The analyses are performed in companion NJOY, AMPX-II, and TORT systems considering the data libraries ENDF/B-VI.8, JENDL3.3, and JEF3.0. The analyses reveal that for this peculiar problem, there is a need to convert all the computer codes to DOUBLE-PRECISION as well as to increase to seven the number of digits of the ANISN library generated by XSDRNPM. Contrary to the traditional diffusion theory codes, TORT k{sub eff} results are very sensitive to the number of both fine and broad groups. For instance, the traditional and very well known two- and four-group structure, largely utilized in several diffusion codes, produced simply unacceptable k{sub eff} results. The highest deviation between calculated and experimental values found for the inversion point was -4.48 deg. C. At first glance, there appears to be a significant discrepancy. However, in terms of reactivity coefficient, this discrepancy means a deviation of -0.90 {+-} 0.05 pcm/deg. C, which indicates that the calculational methodology and related nuclear data libraries meet the desired accuracy (-1.0 pcm/deg. C) for the determination of this parameter for thermal reactors.
Lomond, Jasmine S; Tong, Anthony Z
2011-01-01
Analysis of dissolved methane, ethylene, acetylene, and ethane in water is crucial in evaluating anaerobic activity and investigating the sources of hydrocarbon contamination in aquatic environments. A rapid chromatographic method based on phase equilibrium between water and its headspace is developed for these analytes. The new method requires minimal sample preparation and no special apparatus except those associated with gas chromatography. Instead of Henry's Law used in similar previous studies, partition coefficients are used for the first time to calculate concentrations of dissolved hydrocarbon gases, which considerably simplifies the calculation involved. Partition coefficients are determined to be 128, 27.9, 1.28, and 96.3 at 30°C for methane, ethylene, acetylene, and ethane, respectively. It was discovered that the volume ratio of gas-to-liquid phase is critical to the accuracy of the measurements. The method performance can be readily improved by reducing the volume ratio of the two phases. Method validation shows less than 6% variation in accuracy and precision except at low levels of methane where interferences occur in ambient air. Method detection limits are determined to be in the low ng/L range for all analytes. The performance of the method is further tested using environmental samples collected from various sites in Nova Scotia.
Kim, Jong Kyung; Chang, Sun Ju
2015-08-01
The purpose of this study was to examine the relationship between attitudes toward their organizations and voluntary turnover intention among South Korean clinical nurses. Data from a total of 312 clinical nurses in six hospitals in South Korea were collected for the study. Both hierarchical multiple regression analysis and path analysis were used to analyse the data. The overall fit of the hypothetical model was good. Voluntary turnover intention was found to have significant direct pathways to job embeddedness and organizational commitment. Organizational commitment and satisfaction with organizational rewards had indirect pathways to voluntary turnover intention through job embeddedness. All variances explained 62.3% of the voluntary turnover intention scores. The findings suggest that greater job embeddedness, organizational commitment and satisfaction with organizational rewards lead to lower voluntary turnover intention among clinical nurses in South Korea. © 2014 Wiley Publishing Asia Pty Ltd.
Jacob, Gitta A; Ower, Nicole; Buchholz, Angela
2013-03-01
Experiential avoidance (EA) is an important factor in maintaining different forms of psychopathology including borderline personality pathology (BPD). So far little is known about the functions of EA, BPD features and general psychopathology for positive emotions. In this study we investigated three different anticipated pathways of their influence on positive emotions. A total of 334 subjects varying in general psychopathology &/or BPD features completed an online survey including self-ratings of BPD features, psychopathology, negative and positive emotions, and EA. Measures of positive emotions included both a general self-rating (PANAS) and emotional changes induced by two positive movie clips. Data were analyzed by means of path analysis. In comparing the three path models, one model was found clearly superior: In this model, EA acts as a mediator of the influence of psychopathology, BPD features, and negative emotions in the prediction of both measures of positive emotions. EA plays a central role in maintaining lack of positive emotions. Therapeutic implications and study limitations are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.
Rahmati, Sara; Abovsky, Mark; Pastrello, Chiara; Jurisica, Igor
2017-01-01
Molecular pathway data are essential in current computational and systems biology research. While there are many primary and integrated pathway databases, several challenges remain, including low proteome coverage (57%), low overlap across different databases, unavailability of direct information about underlying physical connectivity of pathway members, and high fraction of protein-coding genes without any pathway annotations, i.e. ‘pathway orphans’. In order to address all these challenges, we developed pathDIP, which integrates data from 20 source pathway databases, ‘core pathways’, with physical protein–protein interactions to predict biologically relevant protein–pathway associations, referred to as ‘extended pathways’. Cross-validation determined 71% recovery rate of our predictions. Data integration and predictions increase coverage of pathway annotations for protein-coding genes to 86%, and provide novel annotations for 5732 pathway orphans. PathDIP (http://ophid.utoronto.ca/pathdip) annotates 17 070 protein-coding genes with 4678 pathways, and provides multiple query, analysis and output options. PMID:27899558
Zeng, Fanmin; Yang, Bangxiang; Fu, Xiaoqian
2015-01-01
Abstract Introduction This study sought to identify a model that explains the relationship between psychosocial factors and chronic pain in female patients, and to explore all of these constructs in a single study and provide a more holistic examination of the overall psychosocial factors that female patients with chronic pain encounter. Methods Female patients with chronic pain (n = 147), aged 20–65 (M = 34.9 years, SD = 11.25), from an outpatient pain clinic completed a cross‐sectional self‐report questionnaire on anxiety, life events, personality, social support, and alexithymia. Data were analyzed by means of path analysis. Results The direct effect of anxiety on female patients with chronic pain was greatest among all the paths. Personality and alexithymia led to chronic pain in female patients only indirectly, mediated by life events. The personality factors of neuroticism and extraversion were associated positively with social support, which had an indirect effect on the influence of life events on chronic pain. However, alexithymia was associated negatively with social support, which had an indirect effect on the influence of life events on chronic pain. Discussion Our findings provide evidence that life events are a mediator in the relationship between personality, social support, alexithymia, and chronic pain in female patients. PMID:26568558
Zhao, Renjie; Evans, James W.; Oliveira, Tiago J.
2016-04-08
Here, a discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possible additional barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for nonuniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessed as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.
Zhao, Renjie; Evans, James W.; Oliveira, Tiago J.
2016-04-08
Here, a discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possible additional barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for nonuniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessedmore » as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.« less
NASA Astrophysics Data System (ADS)
Ma, Junhai; Ren, Wenbo; Zhan, Xueli
2017-04-01
Based on the study of scholars at home and abroad, this paper improves the three-dimensional IS-LM model in macroeconomics, analyzes the equilibrium point of the system and stability conditions, focuses on the parameters and complex dynamic characteristics when Hopf bifurcation occurs in the three-dimensional IS-LM macroeconomics system. In order to analyze the stability of limit cycles when Hopf bifurcation occurs, this paper further introduces the first Lyapunov coefficient to judge the limit cycles, i.e. from a practical view of the business cycle. Numerical simulation results show that within the range of most of the parameters, the limit cycle of 3D IS-LM macroeconomics is stable, that is, the business cycle is stable; with the increase of the parameters, limit cycles becomes unstable, and the value range of the parameters in this situation is small. The research results of this paper have good guide significance for the analysis of macroeconomics system.
Lu, Z Q J; Lowhorn, N D; Wong-Ng, W; Zhang, W; Thomas, E L; Otani, M; Green, M L; Tran, T N; Caylor, C; Dilley, N R; Downey, A; Edwards, B; Elsner, N; Ghamaty, S; Hogan, T; Jie, Q; Li, Q; Martin, J; Nolas, G; Obara, H; Sharp, J; Venkatasubramanian, R; Willigan, R; Yang, J; Tritt, T
2009-01-01
In an effort to develop a Standard Reference Material (SRM™) for Seebeck coefficient, we have conducted a round-robin measurement survey of two candidate materials-undoped Bi2Te3 and Constantan (55 % Cu and 45 % Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of different commercial and custom-built measurement systems and techniques. In this paper we report the detailed statistical analyses on the interlaboratory measurement results and the statistical methodology for analysis of irregularly sampled measurement curves in the interlaboratory study setting. Based on these results, we have selected Bi2Te3 as the prototype standard material. Once available, this SRM will be useful for future interlaboratory data comparison and instrument calibrations.
Bayesian Uncertainty Quantification for Bond Energies and Mobilities Using Path Integral Analysis
Chang, Joshua C.; Fok, Pak-Wing; Chou, Tom
2015-01-01
Dynamic single-molecule force spectroscopy is often used to distort bonds. The resulting responses, in the form of rupture forces, work applied, and trajectories of displacements, are used to reconstruct bond potentials. Such approaches often rely on simple parameterizations of one-dimensional bond potentials, assumptions on equilibrium starting states, and/or large amounts of trajectory data. Parametric approaches typically fail at inferring complicated bond potentials with multiple minima, while piecewise estimation may not guarantee smooth results with the appropriate behavior at large distances. Existing techniques, particularly those based on work theorems, also do not address spatial variations in the diffusivity that may arise from spatially inhomogeneous coupling to other degrees of freedom in the macromolecule. To address these challenges, we develop a comprehensive empirical Bayesian approach that incorporates data and regularization terms directly into a path integral. All experimental and statistical parameters in our method are estimated directly from the data. Upon testing our method on simulated data, our regularized approach requires less data and allows simultaneous inference of both complex bond potentials and diffusivity profiles. Crucially, we show that the accuracy of the reconstructed bond potential is sensitive to the spatially varying diffusivity and accurate reconstruction can be expected only when both are simultaneously inferred. Moreover, after providing a means for self-consistently choosing regularization parameters from data, we derive posterior probability distributions, allowing for uncertainty quantification. PMID:26331254
NASA Technical Reports Server (NTRS)
James, R.; Brownlow, J. D.
1985-01-01
A study is performed under NASA contract to evaluate data from an AN/FPS-16 radar installed for support of flight programs at Dryden Flight Research Facility of NASA Ames Research Center. The purpose of this study is to provide information necessary for improving post-flight data reduction and knowledge of accuracy of derived radar quantities. Tracking data from six flights are analyzed. Noise and bias errors in raw tracking data are determined for each of the flights. A discussion of an altitude bias error during all of the tracking missions is included. This bias error is defined by utilizing pressure altitude measurements made during survey flights. Four separate filtering methods, representative of the most widely used optimal estimation techniques for enhancement of radar tracking data, are analyzed for suitability in processing both real-time and post-mission data. Additional information regarding the radar and its measurements, including typical noise and bias errors in the range and angle measurements, is also presented. This report is in two parts. This is part 2, a discussion of the modeling of propagation path errors.
Roohafza, Hamidreza; Feizi, Awat; Afshar, Hamid; Mazaheri, Mina; Behnamfar, Omid; Hassanzadeh-Keshteli, Ammar; Adibi, Peyman
2016-01-01
AIM: To provide a structural model of the relationship between personality traits, perceived stress, coping strategies, social support, and psychological outcomes in the general population. METHODS: This is a cross sectional study in which the study group was selected using multistage cluster and convenience sampling among a population of 4 million. For data collection, a total of 4763 individuals were asked to complete a questionnaire on demographics, personality traits, life events, coping with stress, social support, and psychological outcomes such as anxiety and depression. To evaluate the comprehensive relationship between the variables, a path model was fitted. RESULTS: The standard electronic modules showed that personality traits and perceived stress are important determinants of psychological outcomes. Social support and coping strategies were demonstrated to reduce the increasing cumulative positive effects of neuroticism and perceived stress on the psychological outcomes and enhance the protective effect of extraversion through decreasing the positive effect of perceived stress on the psychological outcomes. CONCLUSION: Personal resources play an important role in reduction and prevention of anxiety and depression. In order to improve the psychological health, it is necessary to train and reinforce the adaptive coping strategies and social support, and thus, to moderate negative personality traits. PMID:27354968
Aero-thermo-dynamic analysis of a low ballistic coefficient deployable capsule in Earth re-entry
NASA Astrophysics Data System (ADS)
Zuppardi, G.; Savino, R.; Mongelluzzo, G.
2016-10-01
The paper deals with a microsatellite and the related deployable recovery capsule. The aero-brake is folded at launch and deployed in space and is able to perform a de-orbiting controlled re-entry. This kind of capsule, with a flexible, high temperature resistant fabric, thanks to its lightness and modulating capability, can be an alternative to the current ;conventional; recovery capsules. The present authors already analyzed the trajectory and the aerodynamic behavior of low ballistic coefficient capsules during Earth re-entry and Mars entry. In previous studies, aerodynamic longitudinal stability analysis and evaluation of thermal and aerodynamic loads for a possible suborbital re-entry demonstrator were carried out in both continuum and rarefied regimes. The present study is aimed at providing preliminary information about thermal and aerodynamic loads and longitudinal stability for a similar deployable capsule, as well as information about the electronic composition of the plasma sheet and its possible influence on radio communications at the altitudes where GPS black-out could occur. Since the computer tests were carried out at high altitudes, therefore in rarefied flow fields, use of Direct Simulation Monte Carlo codes was mandatory. The computations involved both global aerodynamic quantities (drag and longitudinal moment coefficients) and local aerodynamic quantities (heat flux and pressure distributions along the capsule surface). The results verified that the capsule at high altitude (150 km) is self-stabilizing; it is stable around the nominal attitude or at zero angle of attack and unstable around the reverse attitude or at 180° angle of attack. The analysis also pointed out the presence of extra statically stable equilibrium trim points.
One-Sided Measurement Approach on Ultrasonic Beam Path Analysis in CFRP Composite Laminates
NASA Astrophysics Data System (ADS)
Im, K. H.; Hsu, D. K.; Kim, H. J.; Song, S. J.; Dayal, V.; Barnard, D.; Park, J. W.; Lee, K. S.; Yang, Y. J.; Yang, I. Y.
2008-02-01
Composite materials are attractive for a wide range of applications because of high performance engineering structures. In particular, the importance of carbon-fiber reinforced plastics (CFRP) has been generally recognized in both space and civil aircraft industries; so, CFRP composite laminates are widely used. It is very important to detect defects in composite laminates because they cause the mechanical properties (stiffness, strength) of the laminate to be reduced. As well known for ultrasonic technique for evaluating the defect of CFRP composite laminates, a pitch-catch technique was found to be more practical than normal incidence backwall echo of longitudinal wave to arbitrary flaws in the composite, including fiber orientation, low level porosity, ply waviness, and cracks. The measurement depth using Rayleigh probes can be increased by increasing the separation distance of the transmitting and receiving probes. Also, with the aid of the automatic scanner, the one-sided pitch-catch probe was used to produce C-scan images for mapping out the images with beam profiles. Especially pitch-catch beam path was nondestructively characterized for the specimens when measuring a peak-to-peak amplitude and time-of-flight in order to build the beam profile modeling in the unidirectional CFRP composite laminates. Also, the pitch-catch simulation was performed to predict the beam profile trend of wave propagation in the unidirectional CF/Epoxy composite laminates. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with simulated results and one-side ultrasonic measurement might be very useful to detect the defects in CFRP composites.
NASA Astrophysics Data System (ADS)
Sun, X.; Abshire, J. B.; Ramanathan, A. K.; Mao, J.; Kawa, S. R.
2016-12-01
A multi-wavelength sampling integrated path differential (IPDA) CO2 lidar is analyzed and modeled. The instrument transmits laser pulses at a series of wavelengths across the 1572.33 nm CO2 absorption line. The receiver measures the received laser pulse energy and time of flight at each wavelength. The measurements are then fit to a CO2 absorption line shape to determine the total column CO2 mixing ratio. The receiver model includes effects of solar background, photon detection shot noise, detector dark current, preamplifier noise and laser speckle noise. The least-square curve fit is a linear fit in the optical depth domain and the logarithm of the raw measurements. The column CO2 mixing ratio is proportional to the scaling factor resulted from the curve fit. There are several advantages to performing the curve fit in the optical depth domain: (a) the result is directly proportional to the CO2molecule number density of the column; (b) it is a standard linear least square error fit where the theory is well established; (c) there is no need to separately estimate the off-line optical transmission. The receiver model further gives insight about the effects of various instrument parameters and the difference between the atmosphere model used in the curve fit and the actual atmosphere. For example, we can use the model to estimate the biases in the retrieved CO2 mixing ratio from small errors in the meteorological data used to generate the line shape used in the curve fit. We have shown that the estimated instrument performance using this receiver model agrees with the results from our recent airborne measurements. The receiver model is also used in the simulation of the impact of the lidar measurements of the global greenhouse gas distribution and their projected impact on quantification of surface sources and sinks.
Kanick, S C; Robinson, D J; Sterenborg, H J C M; Amelink, A
2009-11-21
Single fiber reflectance spectroscopy is a method to noninvasively quantitate tissue absorption and scattering properties. This study utilizes a Monte Carlo (MC) model to investigate the effect that optical properties have on the propagation of photons that are collected during the single fiber reflectance measurement. MC model estimates of the single fiber photon path length (L(SF)) show excellent agreement with experimental measurements and predictions of a mathematical model over a wide range of optical properties and fiber diameters. Simulation results show that L(SF) is unaffected by changes in anisotropy (g epsilon [0.8, 0.9, 0.95]), but is sensitive to changes in phase function (Henyey-Greenstein versus modified Henyey-Greenstein). A 20% decrease in L(SF) was observed for the modified Henyey-Greenstein compared with the Henyey-Greenstein phase function; an effect that is independent of optical properties and fiber diameter and is approximated with a simple linear offset. The MC model also returns depth-resolved absorption profiles that are used to estimate the mean sampling depth (Z(SF)) of the single fiber reflectance measurement. Simulated data are used to define a novel mathematical expression for Z(SF) that is expressed in terms of optical properties, fiber diameter and L(SF). The model of sampling depth indicates that the single fiber reflectance measurement is dominated by shallow scattering events, even for large fibers; a result that suggests that the utility of single fiber reflectance measurements of tissue in vivo will be in the quantification of the optical properties of superficial tissues.
NASA Astrophysics Data System (ADS)
Ivanov, A.; Voynikova, D.; Gocheva-Ilieva, S.; Kulina, H.; Iliev, I.
2015-10-01
The monitoring and control of air quality in urban areas is important problem in many European countries. The main air pollutants are observed and a huge amount of data is collected during the last years. In Bulgaria, the air quality is surveyed by the official environmental agency and in many towns exceedances of harmful pollutants are detected. The aim of this study is to investigate the pollution from 9 air pollutants in the town of Dimitrovgrad, Bulgaria in the period of 5 years based on hourly data. Principal Component Analysis (PCA) is used to discover the patterns in the overall pollution and the contribution of the 9 pollutants. In addition the Generalized Path Seeker (GPS) regularized regression method is applied to find dependence of CO (carbon monoxide) with respect to other pollutants and 8 meteorological parameters. It is reported that the CO concentrations are in continuously repeated low level quantities very harmful for human health.
Daghestani, Nart S; Brownsword, Richard; Weidmann, Damien
2014-12-15
Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration. The instrument is driven by a chirped distributed feedback mid-infrared quantum cascade laser centered at ~1283.46 cm^{-1} and covers intense rotational-vibrational transitions from the fundamental ν_{4} band of methane. A full forward model simulating molecular absorption and dispersion profiles, as well as instrumental noise, is demonstrated. The instrument's analytical model is validated and used for quantitative instrumental optimization. The temporal evolution of atmospheric methane mixing ratios is retrieved using a fitting algorithm based on the model. Full error propagation analysis on precision gives a normalized sensitivity of ~3 ppm.m.Hz^{-0.5} for atmospheric methane.
NASA Astrophysics Data System (ADS)
Bong, H. J.; Leem, D.; Kim, J. H.; Im, Y. T.; Lee, M. G.
2016-05-01
The friction coefficient for aluminum alloy 3003 was determined from a specially designed tip test and finite element (FE) simulations. Measured radial tip distance after the tip test was compared to the FE simulations by iteratively changing friction coefficient and the best fitting friction coefficient was determined. To consider strain rate effect on flow stress response during large plastic deformation, a new combined Hollomon- Voce hardening law was proposed. The friction under three different surface conditions was considered by the proposed inverse FE analysis. The results showed that there was obvious strain rate effect on the predicted punch load in the tip test. Moreover, the different friction coefficients were numerically determined for punch/workpiece and die/workpiece interfaces. Two possible causes of this difference were discussed by the analysis on contact normal pressure and slip velocity distributions of the two interfaces.
Doughty, Michael J; Aakre, Bente Monica
2008-09-01
The aim of this study was to compare two methods of assessments of the coefficient of variation (COV) of endothelial cell area. A single image (Topcon SP-2000P specular microscope) was obtained from the central region of the corneal endothelium of 45 healthy white (Norwegian) individuals, aged from 24 to 43 years and without a history of major eye disease or surgery. The image file was printed to A3-size, the cell-cell boundaries marked manually and the areas of the cells measured with a digitiser pad. The same image file was independently processed by the semi-automated Topcon IMAGEnet system. From either method, the cell area data from 100 contiguous cells approximately in the middle portion of the images were used to calculate the average cell area (AVG), the coefficient of variation (COV) on the cell areas and the endothelial cell density (ECD). Both methods produced similar AVG and ECD values that were not statistically different (p >or= 0.180). The SD values on the cell areas increased in relation to the AVG values (Pearson's r >or= 0.557). The resultant COV values were only marginally higher with the manual method (27.8 versus. 26.3 per cent) but the limits of agreement (LoA) for the COV values were rather large at -4.9 to +7.9 per cent. A semi-automated image analysis system can be used to generate COV data for the corneal endothelium similar to those of a manual method. The limits of agreement between the methods are substantial and this probably reflects the extreme sensitivity of the COV calculation to even a few different cell area values. This poor agreement needs to be considered in any comparative studies.
VAMEGHI, Roshanak; AMIR ALI AKBARI, Sedigheh; SAJEDI, Firoozeh; SAJJADI, Homeira; ALAVI MAJD, Hamid
2016-01-01
Objective Given that several factors involved in the incidence or exacerbation of developmental disorders in children, the present study aimed to investigate the relationship between some of the risk factors affecting mothers’ health and development in children using path analysis. Materials & Methods The present cross-sectional analytical study was conducted on 750 mothers and their children in health centers in Tehran, Iran in 2014 enrolled through multi-stage random sampling. Data were collected using a demographic and personal information questionnaire, the Perceived Stress Scale, Beck’s depression Inventory, Spielberger’ anxiety inventory, the WHO domestic violence questionnaire and an ages & stages questionnaire for assessing children’s development. Data were analyzed using SPSS.19 (Chicago, IL, USA) and Lisrel 8.8. Results Developmental delay was observed in 12.1% of the children. The mean stress score was 23.94±8.62 in the mothers, 50.7% of whom showed mild to severe depression, 84.2% moderate to severe anxiety and 35.3% had been subjected to domestic violence. The path analysis showed that children’s development was affected directly by perceived stress (β=-0.09) and depression (β=-0.17) and indirectly by domestic violence (β=-0.05278) and anxiety (β=-0.0357). Of all the variables examined, depression had the biggest influence on development in the children (β=-0.17). The proposed model showed a good fit (GFI=1, RMSEA=0.034). Conclusion Children’s development was influenced indirectly by domestic violence and anxiety and directly by perceived stress and depression in mothers. It is thus suggested that more concern and attention be paid to women’s mental health and the domestic violence they experience. PMID:27843465
NASA Astrophysics Data System (ADS)
Daigle, H.; Rice, M. A.
2015-12-01
Relative permeabilities to water and gas are important parameters for accurate modeling of the formation of methane hydrate deposits and production of methane from hydrate reservoirs. Experimental measurements of gas and water permeability in the presence of hydrate are difficult to obtain. The few datasets that do exist suggest that relative permeability obeys a power law relationship with water or gas saturation with exponents ranging from around 2 to greater than 10. Critical path analysis and percolation theory provide a framework for interpreting the saturation-dependence of relative permeability based on percolation thresholds and the breadth of pore size distributions, which may be determined easily from 3-D images or gas adsorption-desorption hysteresis. We show that the exponent of the permeability-saturation relationship for relative permeability to water is related to the breadth of the pore size distribution, with broader pore size distributions corresponding to larger exponents. Relative permeability to water in well-sorted sediments with narrow pore size distributions, such as Berea sandstone or Toyoura sand, follows percolation scaling with an exponent of 2. On the other hand, pore-size distributions determined from argon adsorption measurements we performed on clays from the Nankai Trough suggest that relative permeability to water in fine-grained intervals may be characterized by exponents as large as 10 as determined from critical path analysis. We also show that relative permeability to the gas phase follows percolation scaling with a quadratic dependence on gas saturation, but the threshold gas saturation for percolation changes with hydrate saturation, which is an important consideration in systems in which both hydrate and gas are present, such as during production from a hydrate reservoir. Our work shows how measurements of pore size distributions from 3-D imaging or gas adsorption may be used to determine relative permeabilities.
Daigle, Hugh; Rice, Mary Anna; Daigle, Hugh
2015-12-14
Relative permeabilities to water and gas are important parameters for accurate modeling of the formation of methane hydrate deposits and production of methane from hydrate reservoirs. Experimental measurements of gas and water permeability in the presence of hydrate are difficult to obtain. The few datasets that do exist suggest that relative permeability obeys a power law relationship with water or gas saturation with exponents ranging from around 2 to greater than 10. Critical path analysis and percolation theory provide a framework for interpreting the saturation-dependence of relative permeability based on percolation thresholds and the breadth of pore size distributions, which may be determined easily from 3-D images or gas adsorption-desorption hysteresis. We show that the exponent of the permeability-saturation relationship for relative permeability to water is related to the breadth of the pore size distribution, with broader pore size distributions corresponding to larger exponents. Relative permeability to water in well-sorted sediments with narrow pore size distributions, such as Berea sandstone or Toyoura sand, follows percolation scaling with an exponent of 2. On the other hand, pore-size distributions determined from argon adsorption measurements we performed on clays from the Nankai Trough suggest that relative permeability to water in fine-grained intervals may be characterized by exponents as large as 10 as determined from critical path analysis. We also show that relative permeability to the gas phase follows percolation scaling with a quadratic dependence on gas saturation, but the threshold gas saturation for percolation changes with hydrate saturation, which is an important consideration in systems in which both hydrate and gas are present, such as during production from a hydrate reservoir. Our work shows how measurements of pore size distributions from 3-D imaging or gas adsorption may be used to determine relative permeabilities.
White Noise Path Integrals in Stochastic Neurodynamics
NASA Astrophysics Data System (ADS)
Carpio-Bernido, M. Victoria; Bernido, Christopher C.
2008-06-01
The white noise path integral approach is used in stochastic modeling of neural activity, where the primary dynamical variables are the relative membrane potentials, while information on transmembrane ionic currents is contained in the drift coefficient. The white noise path integral allows a natural framework and can be evaluated explicitly to yield a closed form for the conditional probability density.
Gollob, Stephan; Kocur, Georg Karl; Schumacher, Thomas; Mhamdi, Lassaad; Vogel, Thomas
2017-02-01
In acoustic emission analysis, common source location algorithms assume, independently of the nature of the propagation medium, a straight (shortest) wave path between the source and the sensors. For heterogeneous media such as concrete, the wave travels in complex paths due to the interaction with the dissimilar material contents and with the possible geometrical and material irregularities present in these media. For instance, cracks and large air voids present in concrete influence significantly the way the wave travels, by causing wave path deviations. Neglecting these deviations by assuming straight paths can introduce significant errors to the source location results. In this paper, a novel source localization method called FastWay is proposed. It accounts, contrary to most available shortest path-based methods, for the different effects of material discontinuities (cracks and voids). FastWay, based on a heterogeneous velocity model, uses the fastest rather than the shortest travel paths between the source and each sensor. The method was evaluated both numerically and experimentally and the results from both evaluation tests show that, in general, FastWay was able to locate sources of acoustic emissions more accurately and reliably than the traditional source localization methods.
Darch, Jonathan; Milner, Ben; Vaseghi, Saeed
2008-12-01
The aim of this work is to develop methods that enable acoustic speech features to be predicted from mel-frequency cepstral coefficient (MFCC) vectors as may be encountered in distributed speech recognition architectures. The work begins with a detailed analysis of the multiple correlation between acoustic speech features and MFCC vectors. This confirms the existence of correlation, which is found to be higher when measured within specific phonemes rather than globally across all speech sounds. The correlation analysis leads to the development of a statistical method of predicting acoustic speech features from MFCC vectors that utilizes a network of hidden Markov models (HMMs) to localize prediction to specific phonemes. Within each HMM, the joint density of acoustic features and MFCC vectors is modeled and used to make a maximum a posteriori prediction. Experimental results are presented across a range of conditions, such as with speaker-dependent, gender-dependent, and gender-independent constraints, and these show that acoustic speech features can be predicted from MFCC vectors with good accuracy. A comparison is also made against an alternative scheme that substitutes the higher-order MFCCs with acoustic features for transmission. This delivers accurate acoustic features but at the expense of a significant reduction in speech recognition accuracy.
USDA-ARS?s Scientific Manuscript database
Critical path analysis (CPA) is a method for estimating macroscopic transport coefficients of heterogeneous materials that are highly disordered at the micro-scale. Developed originally to model conduction in semiconductors, numerous researchers have noted that CPA might also have relevance to flow ...
Meta-Analysis inside and outside Particle Physics: Convergence Using the Path of Least Resistance?
ERIC Educational Resources Information Center
Jackson, Dan; Baker, Rose
2013-01-01
In this note, we explain how the method proposed by Hartung and Knapp provides a compromise between conventional meta-analysis methodology and "unconstrained averaging", as used by the Particle Data Group.
Meta-analysis inside and outside particle physics: convergence using the path of least resistance?
Jackson, Dan; Baker, Rose
2013-06-01
In this note, we explain how the method proposed by Hartung and Knapp provides a compromise between conventional meta-analysis methodology and 'unconstrained averaging', as used by the Particle Data Group. Copyright © 2013 John Wiley & Sons, Ltd.
Meta-Analysis inside and outside Particle Physics: Convergence Using the Path of Least Resistance?
ERIC Educational Resources Information Center
Jackson, Dan; Baker, Rose
2013-01-01
In this note, we explain how the method proposed by Hartung and Knapp provides a compromise between conventional meta-analysis methodology and "unconstrained averaging", as used by the Particle Data Group.
Chhana, Ashika; Aati, Opetaia; Gamble, Gregory D; Callon, Karen E; Doyle, Anthony J; Roger, Mark; McQueen, Fiona M; Horne, Anne; Reid, Ian R; Cornish, Jillian; Dalbeth, Nicola
2016-02-01
To determine the relationship between tophus, erosion and bone remodeling factors in gout. Computed tomography bone erosion and circulating bone factors were measured in adults with tophaceous gout. Multiple regression modeling and path analysis were used to determine predictors of erosion. Tophus number, Māori or Pacific ethnicity, creatinine, receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), and sclerostin were independently associated with erosion. Path analysis showed a direct effect of tophus number on erosion, partially mediated through OPG, RANKL, and sclerostin. Tophus number is strongly associated with bone erosion in gout. Circulating RANKL, OPG, and sclerostin are potential mediators of tophus-related erosion.
Lu, Tao; Wang, Min; Liu, Guangying; Dong, Guang-Hui; Qian, Feng
2016-01-01
It is well known that there is strong relationship between HIV viral load and CD4 cell counts in AIDS studies. However, the relationship between them changes during the course of treatment and may vary among individuals. During treatments, some individuals may experience terminal events such as death. Because the terminal event may be related to the individual's viral load measurements, the terminal mechanism is non-ignorable. Furthermore, there exists competing risks from multiple types of events, such as AIDS-related death and other death. Most joint models for the analysis of longitudinal-survival data developed in literatures have focused on constant coefficients and assume symmetric distribution for the endpoints, which does not meet the needs for investigating the nature of varying relationship between HIV viral load and CD4 cell counts in practice. We develop a mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects to deal with varying relationship between the two endpoints for longitudinal-competing risks survival data. A fully Bayesian inference procedure is established to estimate parameters in the joint model. The proposed method is applied to a multicenter AIDS cohort study. Various scenarios-based potential models that account for partial data features are compared. Some interesting findings are presented.
NASA Astrophysics Data System (ADS)
Thompson, Sarah Ann; Sydeman, William J.; Santora, Jarrod A.; Black, Bryan A.; Suryan, Robert M.; Calambokidis, John; Peterson, William T.; Bograd, Steven J.
2012-08-01
Upwelling in eastern boundary current systems is a primary driver of ecosystem productivity. Typically, peak upwelling occurs during spring and summer, but winter upwelling may also be important to ecosystem functions. In this study, we investigated the hypothesis that winter and spring/summer upwelling, operating through indirect trophic interactions, are important to a suite of top predators in the California Current. To test this hypothesis, we collated information on upwelling, chlorophyll-a concentrations, zooplankton and forage fish, and related these to predator responses including rockfish growth, salmon abundance, seabird productivity and phenology (timing of egg-laying), and whale abundance. Seabird diets served in part as food web indicators. We modeled pathways of response using path analysis and tested for significance of the dominant paths with multiple regression. We found support for the hypothesis that relationships between upwelling and top predator variables were mediated primarily by intermediate trophic levels. Both winter and summer upwelling were important in path models, as were intermediate lower and mid trophic level functional groups represented by chlorophyll-a, zooplankton, and forage fish. Significant pathways of response explained from 50% to 80% of the variation of seabird (Cassin's auklet (Ptychoramphus aleuticus) and common murre (Uria aalge)), humpback whale (Megaptera novaeangliae) and Chinook salmon (Oncorhynchus tshawytscha) dependent variables, whereas splitnose rockfish (Sebastes diploproa) showed no significant response pathways. Upwelling and trophic responses for salmon were established for both the year of ocean entry and the year of return, with zooplankton important in the year of ocean entry and forage fish important in the year of return. This study provides one of the first comparative investigations between upwelling and predators, from fish to marine mammals and birds within a geographically restricted area
ERIC Educational Resources Information Center
Simon, Patricia
2006-01-01
The application range of Cohen's Kappa is extended to the field of sequential observation data, where omission mistakes of an observer may often occur. It is shown how the omission mistakes can be incorporated into the calculation of the Kappa coefficient without violating the statistic it is based on. The enhanced coefficient is termed Kappa…
Analysis of Surface Drainage Paths for Mine Reclamation Using Geographic Information Systems
NASA Astrophysics Data System (ADS)
Choi, Y.; Park, H.
2009-05-01
This study presents an application of GIS-based hydrological modeling and spatial analysis to a coal mining site to effectively control the contaminated surface runoff for mine reclamation. A reliable DEM (Digital Elevation Model) was generated at the study area by detailed topographical surveys. Hydrological analyses were performed to extract the characteristics of drainage system such as flow direction, flow accumulation and catchment area from DEM. The results of spatial analysis showed that some runoff drained through waste dump can flow in the river without any purification. Consequently, several practical actions were suggested to optimize the design of drainage system in the study area for mine reclamation.
NASA Technical Reports Server (NTRS)
Zhu, Sheng-Hu; Stoltzfus, Joel M.; Benz, Frank J.; Yuen, Walter W.
1988-01-01
A theoretical model is being developed jointly by the NASA White Sands Test Facility (WSTF) and the University of California at Santa Barbara (UCSB) to analyze data generated from the WSTF frictional heating test facility. Analyses of the data generated in the first seconds of the frictional heating test are shown to be effective in determining the friction coefficient between the rubbing interfaces. Different friction coefficients for carobn steel and Monel K-500 are observed. The initial condition of the surface is shown to affect only the initial value of the friction coefficient but to have no significant influence on the average steady-state friction coefficient. Rotational speed and the formation of oxide film on the rotating surfaces are shown to have a significant effect on the friction coefficient.
NASA Technical Reports Server (NTRS)
Zhu, Sheng-Hu; Stoltzfus, Joel M.; Benz, Frank J.; Yuen, Walter W.
1988-01-01
A theoretical model is being developed jointly by the NASA White Sands Test Facility (WSTF) and the University of California at Santa Barbara (UCSB) to analyze data generated from the WSTF frictional heating test facility. Analyses of the data generated in the first seconds of the frictional heating test are shown to be effective in determining the friction coefficient between the rubbing interfaces. Different friction coefficients for carobn steel and Monel K-500 are observed. The initial condition of the surface is shown to affect only the initial value of the friction coefficient but to have no significant influence on the average steady-state friction coefficient. Rotational speed and the formation of oxide film on the rotating surfaces are shown to have a significant effect on the friction coefficient.
Kumar, Birendra; Mali, Himanshi; Gupta, Ekta
2014-01-01
Menthofuran rich eight half-sib seed progeny of Mentha piperita (MPS-36) were studied for various genetic parameters, namely, coefficient of variation, heritability, genetic advance, correlation, and path of various plant and oil attributes, namely, plant height, L:S ratio, herb yield, β -myrcene, limonene, 1,8-cineole, menthone, menthofuran, neomenthone, pulegone, and menthol. Maximum genotypic coefficient of variation and genetic advance as percentage of mean were recorded for pulegone, followed by menthofuran and 1,8-cineole. The genotypic correlation in general was higher than phenotypic; positive significant correlation was recorded for limonene with 1,8-cineole and menthone, β -myrcene with limonene, and 1,8-cineole and menthofuran with neomenthol. A high direct positive effect on menthofuran was of neomenthol.
Kumar, Birendra; Mali, Himanshi; Gupta, Ekta
2014-01-01
Menthofuran rich eight half-sib seed progeny of Mentha piperita (MPS-36) were studied for various genetic parameters, namely, coefficient of variation, heritability, genetic advance, correlation, and path of various plant and oil attributes, namely, plant height, L : S ratio, herb yield, β-myrcene, limonene, 1,8-cineole, menthone, menthofuran, neomenthone, pulegone, and menthol. Maximum genotypic coefficient of variation and genetic advance as percentage of mean were recorded for pulegone, followed by menthofuran and 1,8-cineole. The genotypic correlation in general was higher than phenotypic; positive significant correlation was recorded for limonene with 1,8-cineole and menthone, β-myrcene with limonene, and 1,8-cineole and menthofuran with neomenthol. A high direct positive effect on menthofuran was of neomenthol. PMID:24963471
ERIC Educational Resources Information Center
Brown, Steven D.; Tramayne, Selena; Hoxha, Denada; Telander, Kyle; Fan, Xiaoyan; Lent, Robert W.
2008-01-01
This study tested Social Cognitive Career Theory's (SCCT) academic performance model using a two-stage approach that combined meta-analytic and structural equation modeling methodologies. Unbiased correlations obtained from a previously published meta-analysis [Robbins, S. B., Lauver, K., Le, H., Davis, D., & Langley, R. (2004). Do psychosocial…
ERIC Educational Resources Information Center
Brown, Steven D.; Tramayne, Selena; Hoxha, Denada; Telander, Kyle; Fan, Xiaoyan; Lent, Robert W.
2008-01-01
This study tested Social Cognitive Career Theory's (SCCT) academic performance model using a two-stage approach that combined meta-analytic and structural equation modeling methodologies. Unbiased correlations obtained from a previously published meta-analysis [Robbins, S. B., Lauver, K., Le, H., Davis, D., & Langley, R. (2004). Do psychosocial…
NASA Astrophysics Data System (ADS)
Rukhovich, D. I.; Rukhovich, A. D.; Rukhovich, D. D.; Simakova, M. S.; Kulyanitsa, A. L.; Bryzzhev, A. V.; Koroleva, P. V.
2016-08-01
The coefficients of the soil line are often taken into account in calculations of vegetation indices. These coefficients are usually calculated for the entire satellite image, or are taken as constants without any calculations. In both cases, the informativeness of these coefficients is low and insufficient for the needs of soil mapping. In our study, we calculated soil line coefficients at 8000 lattice points for the territory of Plavsk, Arsen'evsk, and Chern districts of Tula oblast on the basis of 34 Landsat 5, 7, and 8 images obtained in 1985-2014. In order to distinguish between the soil line calculated for a given image and the soil line calculated for lattice points on the basis of dozens of multitemporal images, we suggest that the latter can be referred to as the temporal soil line. The temporal soil line is described by a classical equation: NIR = RED a + b, where a is its slope relative to the horizontal axis (RED), and b is the Y-axis (NIR) intercept. Both coefficients were used to create soil maps. The verification of the maps was performed with the use of data on 1985 soil pits. The informativeness of these coefficients appeared to be sufficient for delineation of eight groups of soils of different taxonomic levels: soddy moderately podzolic soils, soddy slightly podzolic soils, soddy-podzolic soils, light gray forest soils, gray forest soils, dark gray forest soils, podzolized chernozems, and leached chernozems. The b coefficient proved to be more informative, as it allowed us to create the soil map precisely on its basis. In order to create the soil map on the basis of the a coefficient, we had to apply some threshold values of the b coefficient. The bare soil on each of Landsat scenes was separated with the help of the mask of agricultural fields and the notion of the spectral neighborhood of soil line (SNSL).
Multilayer thin-film inspection through measurements of reflection coefficients.
Wu, Kai; Lee, Cheng-Chung; Brock, Neal J; Kimbrough, Brad
2011-08-15
A vibration-insensitive interferometer is described to measure the thickness, refraction index and surface profile of thin-film stack at normal incidence. By satisfying the continuous boundary conditions of electric and magnetic fields at interfaces in a multilayer film stack, the reflection coefficient phase of the thin-film stack can be distinguished from the phase of spatial path difference, thus thickness and refraction index can be extracted. The experiment results showed that the measurement precision is significantly increased after the phase analysis was added into the reflectance analysis.
Siderius, Daniel W; Krekelberg, William P; Roberts, Christopher J; Shen, Vincent K
2012-05-07
Protein-protein interactions in solution may be quantified by the osmotic second virial coefficient (OSVC), which can be measured by various experimental techniques including light scattering. Analysis of Rayleigh light scattering measurements from such experiments requires identification of a scattering volume and the thermodynamic constraints imposed on that volume, i.e., the statistical mechanical ensemble in which light scattering occurs. Depending on the set of constraints imposed on the scattering volume, one can obtain either an apparent OSVC, A(2,app), or the true thermodynamic OSVC, B(22)(osm), that is rigorously defined in solution theory [M. A. Blanco, E. Sahin, Y. Li, and C. J. Roberts, J. Chem. Phys. 134, 225103 (2011)]. However, it is unclear to what extent A(2,app) and B(22)(osm) differ, which may have implications on the physical interpretation of OSVC measurements from light scattering experiments. In this paper, we use the multicomponent hard-sphere model and a well-known equation of state to directly compare A(2,app) and B(22)(osm). Our results from the hard-sphere equation of state indicate that A(2,app) underestimates B(22)(osm), but in a systematic manner that may be explained using fundamental thermodynamic expressions for the two OSVCs. The difference between A(2,app) and B(22)(osm) may be quantitatively significant, but may also be obscured in experimental application by statistical uncertainty or non-steric interactions. Consequently, the two OSVCs that arise in the analysis of light scattering measurements do formally differ, but in a manner that may not be detectable in actual application.
NASA Astrophysics Data System (ADS)
Siderius, Daniel W.; Krekelberg, William P.; Roberts, Christopher J.; Shen, Vincent K.
2012-05-01
Protein-protein interactions in solution may be quantified by the osmotic second virial coefficient (OSVC), which can be measured by various experimental techniques including light scattering. Analysis of Rayleigh light scattering measurements from such experiments requires identification of a scattering volume and the thermodynamic constraints imposed on that volume, i.e., the statistical mechanical ensemble in which light scattering occurs. Depending on the set of constraints imposed on the scattering volume, one can obtain either an apparent OSVC, A2,app, or the true thermodynamic OSVC, {B_{22}^{osm}}, that is rigorously defined in solution theory [M. A. Blanco, E. Sahin, Y. Li, and C. J. Roberts, J. Chem. Phys. 134, 225103 (2011), 10.1063/1.3596726]. However, it is unclear to what extent A2,app and {B_{22}^{osm}} differ, which may have implications on the physical interpretation of OSVC measurements from light scattering experiments. In this paper, we use the multicomponent hard-sphere model and a well-known equation of state to directly compare A2,app and {B_{22}^{osm}}. Our results from the hard-sphere equation of state indicate that A2,app underestimates {B_{22}^{osm}}, but in a systematic manner that may be explained using fundamental thermodynamic expressions for the two OSVCs. The difference between A2,app and {B_{22}^{osm}} may be quantitatively significant, but may also be obscured in experimental application by statistical uncertainty or non-steric interactions. Consequently, the two OSVCs that arise in the analysis of light scattering measurements do formally differ, but in a manner that may not be detectable in actual application.
Etherington, W G; Martin, S W; Dohoo, I R; Bosu, W T
1985-07-01
Path analysis was used to determine the interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows. The data used in the analysis were collected on 226 Holstein-Friesian cows calving in a commercial dairy herd during a 17 month period (May 1, 1981 to October 1, 1982). The data were obtained from a double blind study evaluating the effects of gonadotrophin releasing hormone and cloprostenol in postpartum cows. Rectal palpation to assess uterine involution and ovarian activity was performed on each cow on days 15, 24 and 28 postpartum. At the same time, blood samples were collected for subsequent progesterone assay. Data were recorded on the occurrence of reproductive diseases and events from the time of parturition until the diagnosis of pregnancy or until the cow left the herd in the case of culled cows. There was an increase in the incidence of retained placenta, in the percentage of cows with abnormal vaginal discharge in the early postpartum period as well as a delay in uterine involution during the winter months. In addition, cows calving during the winter had prolonged intervals to first estrus, first service and conception compared to cows calving during the summer. (Cows calving during the warmest months, on average, were seen in estrus 24 days sooner, received first service 42 days sooner and conceived 27 days sooner than cows calving during the coldest months of the year).(ABSTRACT TRUNCATED AT 250 WORDS)
Huang, Da Wei; Sherman, Brad T.; Lempicki, Richard A.
2009-01-01
Functional analysis of large gene lists, derived in most cases from emerging high-throughput genomic, proteomic and bioinformatics scanning approaches, is still a challenging and daunting task. The gene-annotation enrichment analysis is a promising high-throughput strategy that increases the likelihood for investigators to identify biological processes most pertinent to their study. Approximately 68 bioinformatics enrichment tools that are currently available in the community are collected in this survey. Tools are uniquely categorized into three major classes, according to their underlying enrichment algorithms. The comprehensive collections, unique tool classifications and associated questions/issues will provide a more comprehensive and up-to-date view regarding the advantages, pitfalls and recent trends in a simpler tool-class level rather than by a tool-by-tool approach. Thus, the survey will help tool designers/developers and experienced end users understand the underlying algorithms and pertinent details of particular tool categories/tools, enabling them to make the best choices for their particular research interests. PMID:19033363
ERIC Educational Resources Information Center
Hu, Chun-mei; Cui, Shu-jing; Wang, Lei
2016-01-01
Objective: To investigate the path analysis of work family conflict, job salary and promotion satisfaction, work engagement to subjective well-being of the primary and middle school principals, and provide advice for enhancing their well-being. Methods: Using convenient sampling, totally 300 primary and middle school principals completed the WFC,…
ERIC Educational Resources Information Center
Harrison, Neil; Agnew, Steve
2016-01-01
This study examines the construction of debt attitudes among 439 first-year undergraduates in England and New Zealand. It works from a conceptual model that predicts that attitudes will be partly determined by a range of social factors, mediated through personality and 'financial literacy'. Path analysis is used to explore this model. The proposed…
ERIC Educational Resources Information Center
Chang, Hsiu-Ju
2016-01-01
This research focus on the temporal path analysis of learning stress, test anxiety, peer stress (classmate relatedness), teacher relatedness, autonomy, and self-regulative performance in junior high school. Owing to the processes of self-determination always combines several negotiations with the interactive perceptions of personal experiences and…
ERIC Educational Resources Information Center
Kelly, William E.
2010-01-01
The relation between reading for pleasure, night-sky watching interest, and openness to experience were examined in a sample of 129 college students. Results of a path analysis examining a mediation model indicated that the influence of night-sky interest on reading for pleasure was not mediated by the broad personality domain openness to…
ERIC Educational Resources Information Center
Chiu, Chung-Yi; Lynch, Ruth Torkelson; Chan, Fong; Rose, Lindsey
2012-01-01
The main objective of this study was to evaluate the health action process approach (HAPA) as a motivational model for dietary self-management for people with multiple sclerosis (MS). Quantitative descriptive research design using path analysis was used. Participants were 209 individuals with MS recruited from the National MS Society and a…
ERIC Educational Resources Information Center
Kelly, William E.
2010-01-01
The relation between reading for pleasure, night-sky watching interest, and openness to experience were examined in a sample of 129 college students. Results of a path analysis examining a mediation model indicated that the influence of night-sky interest on reading for pleasure was not mediated by the broad personality domain openness to…
ERIC Educational Resources Information Center
Wooten, William
1993-01-01
When knowledge, skills, and abilities of four job classes (secretarial/clerical, managerial/administrative, professional/technical, service) were identified, 68% of those determined important for managerial/administrative were also important for secretarial/clerical. Job analysis proved useful in identifying possible career paths, and potential…
ERIC Educational Resources Information Center
Chiu, Chung-Yi; Lynch, Ruth Torkelson; Chan, Fong; Rose, Lindsey
2012-01-01
The main objective of this study was to evaluate the health action process approach (HAPA) as a motivational model for dietary self-management for people with multiple sclerosis (MS). Quantitative descriptive research design using path analysis was used. Participants were 209 individuals with MS recruited from the National MS Society and a…
Singh, Abanish; Babyak, Michael A; Nolan, Daniel K; Brummett, Beverly H; Jiang, Rong; Siegler, Ilene C; Kraus, William E; Shah, Svati H; Williams, Redford B; Hauser, Elizabeth R
2015-06-01
We performed gene-environment interaction genome-wide association analysis (G × E GWAS) to identify SNPs whose effects on metabolic traits are modified by chronic psychosocial stress in the Multi-Ethnic Study of Atherosclerosis (MESA). In Whites, the G × E GWAS for hip circumference identified five SNPs within the Early B-cell Factor 1 (EBF1) gene, all of which were in strong linkage disequilibrium. The gene-by-stress interaction (SNP × STRESS) term P-values were genome-wide significant (Ps = 7.14E-09 to 2.33E-08, uncorrected; Ps = 1.99E-07 to 5.18E-07, corrected for genomic control). The SNP-only (without interaction) model P-values (Ps = 0.011-0.022) were not significant at the conventional genome-wide significance level. Further analysis of related phenotypes identified gene-by-stress interaction effects for waist circumference, body mass index (BMI), fasting glucose, type II diabetes status, and common carotid intimal-medial thickness (CCIMT), supporting a proposed model of gene-by-stress interaction that connects cardiovascular disease (CVD) risk factor endophenotypes such as central obesity and increased blood glucose or diabetes to CVD itself. Structural equation path analysis suggested that the path from chronic psychosocial stress to CCIMT via hip circumference and fasting glucose was larger (estimate = 0.26, P = 0.033, 95% CI = 0.02-0.49) in the EBF1 rs4704963 CT/CC genotypes group than the same path in the TT group (estimate = 0.004, P = 0.34, 95% CI = -0.004-0.012). We replicated the association of the EBF1 SNPs and hip circumference in the Framingham Offspring Cohort (gene-by-stress term P-values = 0.007-0.012) as well as identified similar path relationships. This observed and replicated interaction between psychosocial stress and variation in the EBF1 gene may provide a biological hypothesis for the complex relationship between psychosocial stress, central obesity, diabetes, and cardiovascular disease.
USDA-ARS?s Scientific Manuscript database
Many quantitative and qualitative traits interact to affect lint yield in upland cotton. Breeders should be aware of these traits and their interactions before embarking on a breeding program to improve lint yield. In this study, twelve diverse germplasm lines of upland cotton were used to investiga...
Floquet analysis of Kuznetsov-Ma breathers: A path towards spectral stability of rogue waves
NASA Astrophysics Data System (ADS)
Cuevas-Maraver, J.; Kevrekidis, P. G.; Frantzeskakis, D. J.; Karachalios, N. I.; Haragus, M.; James, G.
2017-07-01
In the present work, we aim at taking a step towards the spectral stability analysis of Peregrine solitons, i.e., wave structures that are used to emulate extreme wave events. Given the space-time localized nature of Peregrine solitons, this is a priori a nontrivial task. Our main tool in this effort will be the study of the spectral stability of the periodic generalization of the Peregrine soliton in the evolution variable, namely the Kuznetsov-Ma breather. Given the periodic structure of the latter, we compute the corresponding Floquet multipliers, and examine them in the limit where the period of the orbit tends to infinity. This way, we extrapolate towards the stability of the limiting structure, namely the Peregrine soliton. We find that multiple unstable modes of the background are enhanced, yet no additional unstable eigenmodes arise as the Peregrine limit is approached. We explore the instability evolution also in direct numerical simulations.
NASA Astrophysics Data System (ADS)
Wang, Z.; Ireland, P. T.; Jones, T. V.
1995-04-01
The heat transfer coefficient over the surface of a pedestal with fillet radii has been measured using thermochromic liquid crystals and the transient heat transfer method. The tests were performed at engine representative Reynolds numbers for a geometry typical of those used in turbine blade cooling systems. The heat conduction process that occurs in the engine was subsequently modeled numerically with a finite element discretization of the solid pedestal. The measured heat transfer coefficients were used to derive the exact boundary conditions applicable to the engine. The temperature field within the pedestal, calculated using the correct heat transfer coefficient distribution, is compared to that calculated using an area-averaged heat transfer coefficient. Metal temperature differences of 90 K are predicted across the blade wall.
NASA Astrophysics Data System (ADS)
Li, Zhao; Hudson, Mary; Paral, Jan; Wiltberger, Michael; Turner, Drew
2016-07-01
The 17-18 March 2015 storm is the largest geomagnetic storm in the Van Allen Probes era to date. The Lyon-Fedder-Mobarry global MHD model has been run for this event using ARTEMIS data as solar wind input. The ULF wave power spectral density of the azimuthal electric field and compressional magnetic field is analyzed in the 0.5-8.3 mHz range. The lowest three azimuthal modes account for 70% of the total power during quiet times. However, during high activity, they are not exclusively dominant. The calculation of the radial diffusion coefficient is presented. We conclude that the electric field radial diffusion coefficient is dominant over the magnetic field coefficient by one to two orders of magnitude. This result contrasts with the dominant magnetic field diffusion coefficient used in most 3-D diffusion models.
da Silva, Gabriel; Chen, Chiung-Chu; Bozzelli, Joseph W
2007-09-06
Aromatic compounds such as toluene and xylene are major components of many fuels. Accurate kinetic mechanisms for the combustion of toluene are, however, incomplete, as they do not accurately model experimental results such as strain rates and ignition times and consistently underpredict conversion. Current kinetic mechanisms for toluene combustion neglect the reactions of the methylphenyl radicals, and we believe that this is responsible, in part, for the shortcomings of these models. We also demonstrate how methylphenyl radical formation is important in the combustion and pyrolysis of other alkyl-substituted aromatic compounds such as xylene and trimethylbenzene. We have studied the oxidation reactions of the methylphenyl radicals with O2 using computational ab initio and density functional theory methods. A detailed reaction submechanism is presented for the 2-methylphenyl radical + O2 system, with 16 intermediates and products. For each species, enthalpies of formation are calculated using the computational methods G3 and G3B3, with isodesmic work reactions used to minimize computational errors. Transition states are calculated at the G3B3 level, yielding high-pressure limit elementary rate constants as a function of temperature. For the barrierless methylphenyl + O2 and methylphenoxy + O association reactions, rate constants are determined from variational transition state theory. Multichannel, multifrequency quantum Rice-Ramsperger-Kassel (qRRK) theory, with master equation analysis for falloff, provides rate constants as a function of temperature and pressure from 800 to 2400 K and 1 x 10(-4) to 1 x 10(3) atm. Analysis of our results shows that the dominant pathways for reaction of the three isomeric methylphenyl radicals is formation of methyloxepinoxy radicals and subsequent ring opening to methyl-dioxo-hexadienyl radicals. The next most important reaction pathway involves formation of methylphenoxy radicals + O in a chain branching process. At lower
NASA Astrophysics Data System (ADS)
Hsu, Ming-Ying; Lin, Yu-Chuan; Chan, Chia-Yen; Lin, Wei-Cheng; Chan, Shenq-Tsong; Huang, Ting-Ming
2012-10-01
The Cassegrain telescope system in this study, is discussion correct lens thermal OPD (Optical Path Difference) effect optical performance. The correct lens assembly are includes several components such as correct lens, lens mount, spacer, mount barrel and retainer. The heat transfer from surrounding to the correct lens barrel will causes optical system aberration. Meanwhile, the off-axis rays path of the OPD must consider lens incidence point and emergence point. The correct lens temperature distribution is calculate the lens barrel heat transfer analysis, the thermal distortion and stress are solve by FEM (Finite Element Method) software. The temperature calculation results can be weighting to each incidence ray path and calculate thermal OPD. The thermal OPD on Z-direction can be fitted by rigid body motion and Zernike polynomial. The fitting results can be used to evaluate the thermal effect on correct lens assembly in telescope system.
NASA Astrophysics Data System (ADS)
Gauglitz, J.; McIlvin, M. R.; Moran, D. M.; Waterbury, J. B.; Saito, M. A.
2016-02-01
Marine diazotrophic cyanobacteria provide a key source of new nitrogen into the oceans and are important contributors to primary production. The geographic distribution of these cyanobacteria is impacted by available iron and phosphorus as well as environmental conditions such as temperature, however available iron concentrations are thought to be particularly critical due to the high demand for iron in cellular processes. Iron bioavailability and microorganismal adaptations to low iron environments may thus play a key role in dictating community structure, however the mechanisms by which cyanobacteria acquire iron and regulate its uptake are not well defined. In this study, the unicellular diazotroph, Crocosphaera watsonii WH8501, was acclimated to a range of bioavailable iron concentrations (from 0.001nM to 8.13nM Fe') using trace metal clean culturing techniques and the proteomes were analyzed by LC/MS-MS. Physiological and proteomic data indicate three distinct phenotypic ranges: iron-replete, iron-limited, and iron-starved. Trends in photosynthetic, carbon fixation and iron storage proteins across the iron gradient indicate that the C. watsonii proteome responds directly to iron availability. Further analysis of relative protein expression, which describes the physiological state of the cell, will lead to insights into how C. watsonii is able to adapt to iron-limited conditions and the resulting biogeochemical implications will be discussed.
Linear and nonlinear dynamic analysis of redundant load path bearingless rotor systems
NASA Technical Reports Server (NTRS)
Murthy, V. R.; Shultz, Louis A.
1994-01-01
The goal of this research is to develop the transfer matrix method to treat nonlinear autonomous boundary value problems with multiple branches. The application is the complete nonlinear aeroelastic analysis of multiple-branched rotor blades. Once the development is complete, it can be incorporated into the existing transfer matrix analyses. There are several difficulties to be overcome in reaching this objective. The conventional transfer matrix method is limited in that it is applicable only to linear branch chain-like structures, but consideration of multiple branch modeling is important for bearingless rotors. Also, hingeless and bearingless rotor blade dynamic characteristics (particularly their aeroelasticity problems) are inherently nonlinear. The nonlinear equations of motion and the multiple-branched boundary value problem are treated together using a direct transfer matrix method. First, the formulation is applied to a nonlinear single-branch blade to validate the nonlinear portion of the formulation. The nonlinear system of equations is iteratively solved using a form of Newton-Raphson iteration scheme developed for differential equations of continuous systems. The formulation is then applied to determine the nonlinear steady state trim and aeroelastic stability of a rotor blade in hover with two branches at the root. A comprehensive computer program is developed and is used to obtain numerical results for the (1) free vibration, (2) nonlinearly deformed steady state, (3) free vibration about the nonlinearly deformed steady state, and (4) aeroelastic stability tasks. The numerical results obtained by the present method agree with results from other methods.
Thermal stress analysis of ceramic gas-path seal components for aircraft turbines
NASA Technical Reports Server (NTRS)
Kennedy, F. E.; Bill, R. C.
1979-01-01
Stress and temperature distributions were evaluated numerically for a blade-tip seal system proposed for gas turbine applications. The seal consists of an abradable ceramic layer on metallic backing with intermediate layers between the ceramic layer and metal substrate. The most severe stresses in the seal, as far as failure is concerned, are tensile stresses at the top of the ceramic layer and shear and normal stresses at the layer interfaces. All these stresses reach their maximum values during the deceleration phase of a test engine cycle. A parametric study was carried out to evaluate the influence of various design parameters on these critical stress values. The influences of material properties and geometric parameters of the ceramic, intermediate, and backing layers were investigated. After the parametric study was completed, a seal system was designed which incorporated materials with beneficial elastic and thermal properties in each layer of the seal. An analysis of the proposed seal design shows an appreciable decrease in the magnitude of the maximum critical stresses over those obtained with earlier configurations.
2011-01-01
Background Chromosomal aneuploidy, that is to say the gain or loss of chromosomes, is the most common abnormality in cancer. While certain aberrations, most commonly translocations, are known to be strongly associated with specific cancers and contribute to their formation, most aberrations appear to be non-specific and arbitrary, and do not have a clear effect. The understanding of chromosomal aneuploidy and its role in tumorigenesis is a fundamental open problem in cancer biology. Results We report on a systematic study of the characteristics of chromosomal aberrations in cancers, using over 15,000 karyotypes and 62 cancer classes in the Mitelman Database. Remarkably, we discovered a very high co-occurrence rate of chromosome gains with other chromosome gains, and of losses with losses. Gains and losses rarely show significant co-occurrence. This finding was consistent across cancer classes and was confirmed on an independent comparative genomic hybridization dataset of cancer samples. The results of our analysis are available for further investigation via an accompanying website. Conclusions The broad generality and the intricate characteristics of the dichotomy of aneuploidy, ranging across numerous tumor classes, are revealed here rigorously for the first time using statistical analyses of large-scale datasets. Our finding suggests that aneuploid cancer cells may use extra chromosome gain or loss events to restore a balance in their altered protein ratios, needed for maintaining their cellular fitness. PMID:21714908
Dynamic analysis and control PID path of a model type gantry crane
NASA Astrophysics Data System (ADS)
Ospina-Henao, P. A.; López-Suspes, Framsol
2017-06-01
This paper presents an alternate form for the dynamic modelling of a mechanical system that simulates in real life a gantry crane type, using Euler’s classical mechanics and Lagrange formalism, which allows find the equations of motion that our model describe. Moreover, it has a basic model design system using the SolidWorks software, based on the material and dimensions of the model provides some physical variables necessary for modelling. In order to verify the theoretical results obtained, a contrast was made between solutions obtained by simulation in SimMechanics-Matlab and Euler-Lagrange equations system, has been solved through Matlab libraries for solving equation’s systems of the type and order obtained. The force is determined, but not as exerted by the spring, as this will be the control variable. The objective is to bring the mass of the pendulum from one point to another with a specified distance without the oscillation from it, so that, the answer is overdamped. This article includes an analysis of PID control in which the equations of motion of Euler-Lagrange are rewritten in the state space, once there, they were implemented in Simulink to get the natural response of the system to a step input in F and then draw the desired trajectories.
Exploring the association between speed and safety: A path analysis approach.
Gargoum, Suliman A; El-Basyouny, Karim
2016-08-01
Road safety is influenced by many factors; these factors include characteristics of the road, climate, traffic and, most importantly, vehicle speeds. Previous research shows that increases in speed are typically associated with an increased collision risk. Moreover, previous studies have also found relationships between road and traffic characteristics and collisions. In addition, these features have also been found to affect speeds. This paper aims to model all the aforementioned relationships simultaneously using a Structural Equation Modelling approach. More specifically, the paper attempts to model the relationship between average speed and collision frequency, while taking into account the effects of factors that confound the relationship. Moreover, the analysis attempts to assess the mediated effects that some variables have on collisions through their effects on speed. The data used in this study originated from 353 two-lane urban roads in the city of Edmonton, Canada. The average speeds were obtained from 35 million speed survey observations collected over a five-year period. The speed data are linked to the crash frequency at each location during the same time frame, along with the other factors (road, traffic and climate). The results show that, among others, average speed, volume, segment length, medians and horizontal curves all have statistically significant effects on collisions. On the other hand, shoulders, speed limits and vehicle-lengths are some variables that significantly influence speeds. The results also show that the effects of some variables on safety are indeed mediated through speeds (both partial and full mediation is observed). These findings provide valuable insight that may assist decision makers in choosing and developing alternative speed management strategies, which, in turn, could help improve safety. Copyright © 2016 Elsevier Ltd. All rights reserved.
A simple and accurate algorithm for path integral molecular dynamics with the Langevin thermostat
NASA Astrophysics Data System (ADS)
Liu, Jian; Li, Dezhang; Liu, Xinzijian
2016-07-01
We introduce a novel simple algorithm for thermostatting path integral molecular dynamics (PIMD) with the Langevin equation. The staging transformation of path integral beads is employed for demonstration. The optimum friction coefficients for the staging modes in the free particle limit are used for all systems. In comparison to the path integral Langevin equation thermostat, the new algorithm exploits a different order of splitting for the phase space propagator associated to the Langevin equation. While the error analysis is made for both algorithms, they are also employed in the PIMD simulations of three realistic systems (the H2O molecule, liquid para-hydrogen, and liquid water) for comparison. It is shown that the new thermostat increases the time interval of PIMD by a factor of 4-6 or more for achieving the same accuracy. In addition, the supplementary material shows the error analysis made for the algorithms when the normal-mode transformation of path integral beads is used.
A simple and accurate algorithm for path integral molecular dynamics with the Langevin thermostat.
Liu, Jian; Li, Dezhang; Liu, Xinzijian
2016-07-14
We introduce a novel simple algorithm for thermostatting path integral molecular dynamics (PIMD) with the Langevin equation. The staging transformation of path integral beads is employed for demonstration. The optimum friction coefficients for the staging modes in the free particle limit are used for all systems. In comparison to the path integral Langevin equation thermostat, the new algorithm exploits a different order of splitting for the phase space propagator associated to the Langevin equation. While the error analysis is made for both algorithms, they are also employed in the PIMD simulations of three realistic systems (the H2O molecule, liquid para-hydrogen, and liquid water) for comparison. It is shown that the new thermostat increases the time interval of PIMD by a factor of 4-6 or more for achieving the same accuracy. In addition, the supplementary material shows the error analysis made for the algorithms when the normal-mode transformation of path integral beads is used.
Tang, Yanhua; Wang, Haiyi; Ma, Lu; Zhang, Xiaojing; Yu, Guo; Li, Jie; Ye, Huiyi
2016-08-01
To define correlations between the pathological grades of hepatocellular carcinomas (HCCs) and apparent diffusion coefficients (ADCs) derived using breath-holding diffusion-weighted imaging (BH-DWI). We retrospectively evaluated 94 patients (105 lesions) with pathologically proved HCC who underwent hepatic DWI on a 3.0-T MR platform. HCCs were divided into five groups: well-differentiated (n = 10), well-to-moderately differentiated (n = 11), moderately differentiated (n = 51), moderately to poorly differentiated (n = 20), and poorly differentiated (n = 13) groups. The ADCs of carcinomas across different histological grades were compared by one-way analysis of variance. Spearman's rank correlation test was used to analyze correlations between the degree of histopathological differentiation and ADC. Results were corrected for multiple comparisons using the Bonferroni correction. The BH technique yielded ADC values that differed significantly by the extent of differentiation (F = 8.392, p < 0.001). A significant negative correlation was found between the extent of differentiation and ADCs (r = -0.462, p < 0.001). The mean ADC values of poorly differentiated HCCs were significantly lower than the well-, well-to-moderately, moderately, and moderately to poorly differentiated HCCs (p values were <0.001, <0.001, 0.003, and 0.031, respectively). ADC values obtained with BH-DWI may be of importance to non-invasively predict HCC tumor differentiation, and the extent of histological HCC differentiation was inversely correlated with ADC values.
NASA Astrophysics Data System (ADS)
Virgo, Simon; von Hagke, Christoph; Urai, Janos L.
2017-04-01
Boudins are periodic structures that form by layer parallel extension in mechanically layered rocks. The characteristics of boudins such as orientation and geometry provide constraints on the paleo stress field as well as the rheology of the rocks during deformation. However, most characterizations of boudinage are based on 2D observations and do not consider the 3-dimensional complexity and potentially non-coaxial polyphase genesis of boudinage structures. In marble quarries in the high grade complex on Naxos, Greece, we studied spectacular outcrops of amphibolite and pegmatite boudins, in combination with serial slicing of quarried blocks to reconstruct the 3D boudin structures. We identified five boudin generations with two distinct generations of early, high grade pinch-and-swell followed by two generations of brittle shearband and torn boudins formed along the retrograde path under greenschist facies conditions. The five generations of boudinage indicate that E-W compression is the main mode of deformation in the marbles. The axis of extension changes from subvertical during pinch-and swell deformation to subhorizontal N-S extension at later stages of deformation. Later phases of boudinage are influenced by existing boudin geometries, producing complex structures in 3D. In 2D section the complexity is not directly apparent and reveals itself only after statistical analysis of long continuous sections. Apart from implications for the regional geology, our findings highlight the importance of 3D characterization of boudinage structures for boudin classification. The insights we gain from the analysis of multiphase boudinage structures on Naxos are the basis for quantitative boudin analysis to infer rheology, effective stress, vorticity and strain, and establish a boudin classification scheme with appeal to a complete mechanics.
NASA Astrophysics Data System (ADS)
Cano, Francisco; García, Ángela; Berbén, A. B. G.; Justicia, Fernando
2014-07-01
The purpose of this research was to build and test a conceptual model of the complex interrelationships between students' learning in science (learning approaches and self-regulation), their reading comprehension, question-asking in class and science achievement. These variables were measured by means of a test and a series of questionnaires administered to 604 ninth-grade students, and the data collected were analysed using a correlational, cross-sectional design. Results of a path analysis indicated that (a) students' self-regulated and intentional knowledge-constructing activity (self-regulated strategy use, deep approach and knowledge-building) were what chiefly accounted for their question-asking in class; (b) question-asking (high and low levels) was related directly to reading comprehension and indirectly, through its contribution to the this, to academic achievement; (c) reading comprehension was directly and negatively associated with surface approach and indirectly and positively related to deep approach and knowledge-building; and (d) some of these variables, particularly reading comprehension, accounted for academic achievement in science. This model explained nearly 30% of the variance in academic achievement and provided a substantial and distinctive insight into the web of interrelationships among these variables. Implications for future research and science teaching and learning are discussed (e.g. the importance of supporting students' efforts to learn science in a meaningful, active and self-regulated way and of improving their reading comprehension).
Oliveira, Aline Gaudard E Silva de; Reichenheim, Michael Eduardo; Moraes, Claudia Leite; Howard, Louise Michele; Lobato, Gustavo
2017-04-01
The aim of the study was to explore the pathways by which childhood sexual abuse (CSA), psychological and physical intimate partner violence (IPV) during pregnancy, and other covariates relate to each other and to posttraumatic stress disorder (PTSD) symptoms in the postpartum period. The sample comprised 456 women who gave birth at a maternity service for high-risk pregnancies in Rio de Janeiro, Brazil, interviewed at 6-8 weeks after birth. A path analysis was carried out to explore the postulated pathways between exposures and outcome. Trauma History Questionnaire, Conflict Tactics Scales and Posttraumatic Stress Disorder Checklist were used to assess information about exposures of main interest and outcome. The link between CSA and PTSD symptoms was mediated by history of trauma, psychiatric history, psychological IPV, and fear of childbirth during pregnancy. Physical IPV was directly associated with postnatal PTSD symptoms, whereas psychological IPV connection seemed to be partially mediated by physical abuse and fear of childbirth during pregnancy. The role of CSA, IPV, and other psychosocial characteristics on the occurrence of PTSD symptoms following childbirth as well as the intricate network of these events should be acknowledged in clinic and intervention approaches.