Nonferromagnetic linear variable differential transformer
Ellis, James F.; Walstrom, Peter L.
1977-06-14
A nonferromagnetic linear variable differential transformer for accurately measuring mechanical displacements in the presence of high magnetic fields is provided. The device utilizes a movable primary coil inside a fixed secondary coil that consists of two series-opposed windings. Operation is such that the secondary output voltage is maintained in phase (depending on polarity) with the primary voltage. The transducer is well-suited to long cable runs and is useful for measuring small displacements in the presence of high or alternating magnetic fields.
Signal Enhancement with Variable Span Linear Filters
Benesty, Jacob; Christensen, Mads Græsbøll; Jensen, Jesper Rindom
This book introduces readers to the novel concept of variable span speech enhancement filters, and demonstrates how it can be used for effective noise reduction in various ways. Further, the book provides the accompanying Matlab code, allowing readers to easily implement the main ideas discussed....... Variable span filters combine the ideas of optimal linear filters with those of subspace methods, as they involve the joint diagonalization of the correlation matrices of the desired signal and the noise. The book shows how some well-known filter designs, e.g. the minimum distortion, maximum signal......-to-noise ratio, Wiener, and tradeoff filters (including their new generalizations) can be obtained using the variable span filter framework. It then illustrates how the variable span filters can be applied in various contexts, namely in single-channel STFT-based enhancement, in multichannel enhancement in both...
Signal enhancement with variable span linear filters
Benesty, Jacob; Jensen, Jesper R
2016-01-01
This book introduces readers to the novel concept of variable span speech enhancement filters, and demonstrates how it can be used for effective noise reduction in various ways. Further, the book provides the accompanying Matlab code, allowing readers to easily implement the main ideas discussed. Variable span filters combine the ideas of optimal linear filters with those of subspace methods, as they involve the joint diagonalization of the correlation matrices of the desired signal and the noise. The book shows how some well-known filter designs, e.g. the minimum distortion, maximum signal-to-noise ratio, Wiener, and tradeoff filters (including their new generalizations) can be obtained using the variable span filter framework. It then illustrates how the variable span filters can be applied in various contexts, namely in single-channel STFT-based enhancement, in multichannel enhancement in both the time and STFT domains, and, lastly, in time-domain binaural enhancement. In these contexts, the properties of ...
Signal Enhancement with Variable Span Linear Filters
Benesty, Jacob; Christensen, Mads Græsbøll; Jensen, Jesper Rindom
This book introduces readers to the novel concept of variable span speech enhancement filters, and demonstrates how it can be used for effective noise reduction in various ways. Further, the book provides the accompanying Matlab code, allowing readers to easily implement the main ideas discussed....... Variable span filters combine the ideas of optimal linear filters with those of subspace methods, as they involve the joint diagonalization of the correlation matrices of the desired signal and the noise. The book shows how some well-known filter designs, e.g. the minimum distortion, maximum signal...
Linear odd Poisson bracket on Grassmann variables
A linear odd Poisson bracket (antibracket) realized solely in terms of Grassmann variables is suggested. It is revealed that the bracket, which corresponds to a semi-simple Lie group, has at once three Grassmann-odd nilpotent Δ-like differential operators of the first, the second and the third orders with respect to Grassmann derivatives, in contrast with the canonical odd Poisson bracket having the only Grassmann-odd nilpotent differential Δ-operator of the second order. It is shown that these Δ-like operators together with a Grassmann-odd nilpotent Casimir function of this bracket form a finite-dimensional Lie superalgebra. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Measures of Linear Correlation for Multiple Variables
Wang, Jianji; Zheng, Nanning
2014-01-01
Multivariate linear correlation analysis plays an important role in various fields such as statistics, economics, and big data analytics. However, there was no compact formulation to define and measure multivariate linear correlation. In this paper, we propose a pair of coupling coefficients, the multivariate linear correlation coefficient (LCC) and linear incorrelation coefficient (LIC), to measure the strength of multivariate linear correlation and linear irrelevance. Pearson's correlation ...
Solitary Wave in Linear ODE with Variable Coefficients
LIU Shi-Da; FU Zun-Tao; LIU Shi-Kuo; XIN Guo-Jun; LIANG Fu-Ming; FENG Bei-Ye
2003-01-01
In this paper, the linear ordinary differential equations with variable coefficients are obtained from thecontrolling equations satisfied by wavelet transform or atmospheric internal gravity waves, and these linear equationscan be further transformed into Weber equations. From Weber equations, the homoclinic orbit solutions can be derived,so the solitary wave solutions to linear equations with variable coefficients are obtained.
MN112: a new Galactic candidate Luminous Blue Variable
Gvaramadze, V V; Fabrika, S; Sholukhova, O; Berdnikov, L N; Cherepashchuk, A M; Zharova, A V
2009-01-01
We report the discovery of a new Galactic candidate Luminous Blue Variable (cLBV) via detection of an infrared circular nebula and follow-up spectroscopy of its central star. The nebula, MN112, is one of many dozens of circular nebulae detected at 24 $\\mu$m the Spitzer Space Telescope archival data, whose morphology is similar to that of nebulae associated with known (c)LBVs and related evolved massive stars. Specifically, the core-halo morphology of MN112 bears a striking resemblance to the circumstellar nebula associated with the Galactic cLBV GAL 079.29+00.46, which suggests that both nebulae might have a similar origin and that the central star of MN112 is a LBV. The spectroscopy of the central star showed that its spectrum is almost identical to that of the bona fide LBV P Cygni, which also supports the LBV classification of the object. To further constrain the nature of MN112, we searched for signatures of possible high-amplitude ($\\ga 1$ mag) photometric variability of the central star using archival a...
Dimension Reduction of the Explanatory Variables in Multiple Linear Regression
Filzmoser, P.; Croux, Christophe
2003-01-01
Abstract: In classical multiple linear regression analysis problems will occur if the regressors are either multicollinear or if the number of regressors is larger than the number of observations. In this note a new method is introduced which constructs orthogonal predictor variables in a way to have a maximal correlation with the dependent variable. The predictor variables are linear combinations of the original regressors. This method allows a major reduction of the number of predictors ...
Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects
Oliveira, A S; Cieslinski, D; Jablonski, F J; Silva, K M G; Almeida, L A; Rodriguez-Ardila, A; Palhares, M S
2016-01-01
The increasing number of synoptic surveys made by small robotic telescopes, as the photometric Catalina Real-Time Transient Survey (CRTS), represents a unique opportunity for the discovery of new variable objects, improving the samples of many classes of variables. Our goal is the discovery of new magnetic Cataclysmic Variables (mCVs). They are rare objects, which probe interesting accretion scenarios controlled by the white-dwarf magnetic field. We performed an optical spectroscopic survey to search for signatures of magnetic accretion on 47 variable objects selected mostly from CRTS. Our sample includes 13 polar strong candidates, from which 5 are new discoveries. Accretion disks seem to be present in other 19 objects. One is a previously known probable intermediate polar. We suggest 8 other objects could also be of this class. In particular, 7 of them have spectra consistent with short-period intermediate polars. We suggest one object is a novalike of the VY~Scl class. We also caught one dwarf nova in erup...
Fuzzy variable linear programming with fuzzy technical coefficients
Sanwar Uddin Ahmad
2012-11-01
Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Fuzzy linear programming is an application of fuzzy set theory in linear decision making problems and most of these problems are related to linear programming with fuzzy variables. In this paper an approximate but convenient method for solving these problems with fuzzy non-negative technical coefficient and without using the ranking functions, is proposed. With the help of numerical examples, the method is illustrated.
Linear EV model with replicate observations on independent variables
LIU; Jixue; ZHANG; Sanguo; CHEN; Xiru
2006-01-01
This paper studies the linear EV model when replicate observations are made only on independent variables. We construct the estimates of regression coefficients and prove the consistency and asymptotic normality under some proper conditions. Results obtained reveal the difference between the case where the independent and dependent variables are observed repeatedly and simultaneously and the case studied in this article.
ASYMPTOTIC ANALYSIS OF LINEARLY ELASTIC SHALLOW SHELLS WITH VARIABLE THICKNESS
无
2001-01-01
The author considers a linearly elastic shallow shell with variable thickness and shows that, as the thickness of the shell goes to zero, the solution of the three-dimensional equations converges to the solution of the two-dimensional shallow shell equations with variable thickness.
A Partitioning and Bounded Variable Algorithm for Linear Programming
Sheskin, Theodore J.
2006-01-01
An interesting new partitioning and bounded variable algorithm (PBVA) is proposed for solving linear programming problems. The PBVA is a variant of the simplex algorithm which uses a modified form of the simplex method followed by the dual simplex method for bounded variables. In contrast to the two-phase method and the big M method, the PBVA does…
A Non-Gaussian Spatial Generalized Linear Latent Variable Model
Irincheeva, Irina
2012-08-03
We consider a spatial generalized linear latent variable model with and without normality distributional assumption on the latent variables. When the latent variables are assumed to be multivariate normal, we apply a Laplace approximation. To relax the assumption of marginal normality in favor of a mixture of normals, we construct a multivariate density with Gaussian spatial dependence and given multivariate margins. We use the pairwise likelihood to estimate the corresponding spatial generalized linear latent variable model. The properties of the resulting estimators are explored by simulations. In the analysis of an air pollution data set the proposed methodology uncovers weather conditions to be a more important source of variability than air pollution in explaining all the causes of non-accidental mortality excluding accidents. © 2012 International Biometric Society.
Free piston variable-stroke linear-alternator generator
Haaland, C.M.
1998-12-15
A free-piston variable stroke linear-alternator AC power generator for a combustion engine is described. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod. 8 figs.
Free piston variable-stroke linear-alternator generator
Haaland, Carsten M. (Dadeville, AL)
1998-01-01
A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.
Multi-linear variable separation approach to nonlinear systems
Xiao-yan TANG; Sen-yue LOU
2009-01-01
The multi-linear variable separation approach is reviewed in this article. The method has been recently established and successfully solved a large number of nonlinear systems. One of the most exciting findings is that the basic multi-linear variable separation solution can be expressed by a universal formula including two (1+1)-dimensional functions, and at least one is arbitrary for integrable systems.Furthermore, the method has been extended in two different ways so as to enroll more low dimensional functions in the solution.
Identification of the Predicator Variables of Candidate Teacher Teaching Motivations
Bozpolat, Ebru
2016-01-01
The purpose of this study was to determine whether the internal and external teaching motivations of 3rd and 4th year students of the Faculty of Education of Cumhuriyet University are predicted by the variables of gender, department, year level, conscious preference of department they are studying in, whether there is a teacher in their family,…
Noise Reduction with Optimal Variable Span Linear Filters
Jensen, Jesper Rindom; Benesty, Jacob; Christensen, Mads Græsbøll
2016-01-01
In this paper, the problem of noise reduction is addressed as a linear filtering problem in a novel way by using concepts from subspace-based enhancement methods, resulting in variable span linear filters. This is done by forming the filter coefficients as linear combinations of a number of eigen......In this paper, the problem of noise reduction is addressed as a linear filtering problem in a novel way by using concepts from subspace-based enhancement methods, resulting in variable span linear filters. This is done by forming the filter coefficients as linear combinations of a number...... included in forming the filter. Using these concepts, a number of different filter designs are considered, like minimum distortion, Wiener, maximum SNR, and tradeoff filters. Interestingly, all these can be expressed as special cases of variable span filters. We also derive expressions for the speech...... distortion and noise reduction of the various filter designs. Moreover, we consider an alternative approach, wherein the filter is designed for extracting an estimate of the noise signal, which can then be extracted from the observed signals, which is referred to as the indirect approach. Simulations...
Kaya, Deniz; Izgiol, Dilek; Kesan, Cenk
2014-01-01
The aim was to determine elementary mathematics teacher candidates' problem solving skills and analyze problem solving skills according to various variables. The data were obtained from total 306 different grade teacher candidates receiving education in Department of Elementary Mathematics Education, Buca Faculty of Education, Dokuz Eylul…
Estimation and variable selection for generalized additive partial linear models
Wang, Li
2011-08-01
We study generalized additive partial linear models, proposing the use of polynomial spline smoothing for estimation of nonparametric functions, and deriving quasi-likelihood based estimators for the linear parameters. We establish asymptotic normality for the estimators of the parametric components. The procedure avoids solving large systems of equations as in kernel-based procedures and thus results in gains in computational simplicity. We further develop a class of variable selection procedures for the linear parameters by employing a nonconcave penalized quasi-likelihood, which is shown to have an asymptotic oracle property. Monte Carlo simulations and an empirical example are presented for illustration. © Institute of Mathematical Statistics, 2011.
Oscillations in linear difference equations with variable coefficients
Ch. G. Philos
1991-01-01
Full Text Available A class of linear difference equations with variable coefficients is considered. Sufficient conditions and necessary conditions for the oscillation of the solutions are established. In the special cases where the coefficients are constant or periodic the conditions become both necessary and sufficient.
Stability of a linear oscillator with variable parameters
Alexander O. Ignatyev
1997-01-01
A criterion of asymptotic stability for a linear oscillator with variable parameters is obtained. It is shown that this criterion is close to a necessary and sufficient conditions of asymptotic stability. An instability theorem is proved, and a mechanical example is considered.
Linear latent variable models: the lava-package
Holst, Klaus Kähler; Budtz-Jørgensen, Esben
2013-01-01
An R package for specifying and estimating linear latent variable models is presented. The philosophy of the implementation is to separate the model specification from the actual data, which leads to a dynamic and easy way of modeling complex hierarchical structures. Several advanced features are...
Support vector classification algorithm based on variable parameter linear programming
Xiao Jianhua; Lin Jian
2007-01-01
To solve the problems of SVM in dealing with large sample size and asymmetric distributed samples, a support vector classification algorithm based on variable parameter linear programming is proposed.In the proposed algorithm, linear programming is employed to solve the optimization problem of classification to decrease the computation time and to reduce its complexity when compared with the original model.The adjusted punishment parameter greatly reduced the classification error resulting from asymmetric distributed samples and the detailed procedure of the proposed algorithm is given.An experiment is conducted to verify whether the proposed algorithm is suitable for asymmetric distributed samples.
Notes on Multi-linear Variable Separation Approach
SHEN Shou-Feng; ZHANG Jun; PAN Zu-Liang
2005-01-01
The multi-linear variable separation approach method is very useful to solve (2+1)-dimensional integrable systems. In this letter, we extend this method to solve (1+1)-dimensional Boiti system, (2+1)-dimensional Burgers system, (2+1)-dimensional breaking soliton system, and (2+1)-dimensional Maccari system. Some new exact solutions are obtained and the universal formula obtained from many (2+1)-dimensional systems is extended or modified.
Stability theorems for multidimensional linear systems with variable parameters
Shrivastava, S. K.
1981-01-01
A Liapunov-type approach is used to derive two equivalent theorems which govern the stability of coupled linear systems with varying multiple parameters. The theorems generalize some of the existing theorems applicable to systems with constant parameters and the Sonin-Polya theorem applicable to a single-degree-of-freedom system with variable coefficients. As an illustration, the proposed theorems are applied to mechanical systems with varying inertia, stiffness, gyroscopic, and damping terms, and velocity and position-dependent forces.
Kao, Wil; Prince, Thomas A; Tang, Sumin; Ene, Irina; Kim, Kyu Bin; Levitan, David; Kulkarni, Shrinivas R; Laher, Russ R
2016-01-01
We present a sample of 59 periodic variables from the Palomar Transient Factory, selected from published catalogues of white dwarf (WD) candidates. The variability can likely be attributed to ellipsoidal variation of the tidally distorted companion induced by the gravity of the primary (WD or hot subdwarf) or to the reflection of hot emission by a cooler companion. We searched 11,311 spectroscopically or photometrically selected WD candidates from three hot star/WD catalogues, using the Lomb-Scargle periodogram to single out promising sources. We present period estimates for the candidates, 45 of which were not previously identified as periodic variables, and find that most have a period shorter than a few days. Additionally, we discuss the eclipsing systems in our sample and present spectroscopic data on selected sources.
Kao, Wil; Kaplan, David L.; Prince, Thomas A.; Tang, Sumin; Ene, Irina; Kim, Kyu Bin; Levitan, David; Kulkarni, Shrinivas R.; Laher, Russ R.
2016-09-01
We present a sample of 59 periodic variables from the Palomar Transient Factory, selected from published catalogues of white dwarf (WD) candidates. The variability can likely be attributed to ellipsoidal variation of the tidally distorted companion induced by the gravity of the primary (WD or hot subdwarf) or to the reflection of hot emission by a cooler companion. We searched 11 311 spectroscopically or photometrically selected WD candidates from three hot star/WD catalogues, using the Lomb-Scargle periodogram to single out promising sources. We present period estimates for the candidates, 45 of which were not previously identified as periodic variables, and find that most have a period shorter than a few days. Additionally, we discuss the eclipsing systems in our sample and present spectroscopic data on selected sources.
Exploring the Variable Sky with LINEAR. III. Classification of Periodic Light Curves
Palaversa, Lovro; Ivezić, Željko; Eyer, Laurent; Ruždjak, Domagoj; Sudar, Davor; Galin, Mario; Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana; Božić, Hrvoje; Loebman, Sarah; Sesar, Branimir; Rimoldini, Lorenzo; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Stuart, J. Scott; Becker, Andrew C.; Srdoč, Gregor; Wozniak, Przemyslaw; Oluseyi, Hakeem
2013-10-01
We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ~0.03 mag at r = 15 to ~0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ~200,000 most probable candidate variables with r learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median period increases from 5.9 hr to 8.8 hr. These large samples of robustly classified variable stars will enable detailed statistical studies of the Galactic structure and physics of binary and other stars and we make these samples publicly available.
IR Microspectrometers based on Linear-Variable Optical Filters
Emadi, A.; Wu, H; De Graaf, G.; Wolffenbuttel, R.F.
2013-01-01
This paper presents the design, fabrication and characterization of Infra-Red (IR) Linear Variable Optical Filter (LVOF)-based micro-spectrometers. Two LVOF microspectrometer designs have been realized: one for operating in the 1400 nm to 2500 nm wavelength range and another between 3000 nm and 5000 nm. The IR LVOFs have been fabricated in an IC-Compatible process using resist reflow. The LVOF provides the possibility to have a small size, robust and high-resolution micro-spectrometer in the ...
Spectral measurement using IC-compatible linear variable optical filter
Emadi, A.; Grabarnik, S.; Wu, H; De Graaf, G.; Hedsten, K.; Enoksson, P.; Correia, J. H.; Wolffenbuttel, R.F.
2010-01-01
This paper reports on the functional and spectral characterization of a microspectrometer based on a CMOS detector array covered by an IC-Compatible Linear Variable Optical Filter (LVOF). The Fabry-Perot LVOF is composed of 15 dielectric layers with a tapered middle cavity layer, which has been fabricated in an IC-Compatible process using resist reflow. A pattern of trenches is made in a resist layer by lithography and followed by a reflow step result in a smooth tapered resist layer. The lit...
Explicit estimating equations for semiparametric generalized linear latent variable models
Ma, Yanyuan
2010-07-05
We study generalized linear latent variable models without requiring a distributional assumption of the latent variables. Using a geometric approach, we derive consistent semiparametric estimators. We demonstrate that these models have a property which is similar to that of a sufficient complete statistic, which enables us to simplify the estimating procedure and explicitly to formulate the semiparametric estimating equations. We further show that the explicit estimators have the usual root n consistency and asymptotic normality. We explain the computational implementation of our method and illustrate the numerical performance of the estimators in finite sample situations via extensive simulation studies. The advantage of our estimators over the existing likelihood approach is also shown via numerical comparison. We employ the method to analyse a real data example from economics. © 2010 Royal Statistical Society.
Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects
De Oliveira, A. S.; Rodrigues, C. V.; CIESLINSKI, D.; Jablonski, F. J.; Silva, K. M. G.; Almeida, L. A.; Rodriguez-Ardila, A.; M.S. Palhares
2016-01-01
The increasing number of synoptic surveys made by small robotic telescopes, as the photometric Catalina Real-Time Transient Survey (CRTS), represents a unique opportunity for the discovery of new variable objects, improving the samples of many classes of variables. Our goal is the discovery of new magnetic Cataclysmic Variables (mCVs). They are rare objects, which probe interesting accretion scenarios controlled by the white-dwarf magnetic field. We performed an optical spectroscopic survey t...
Variable Selection in the Partially Linear Errors-in-Variables Models for Longitudinal Data
Yi-ping YANG; Liu-gen XUE; Wei-hu CHENG
2012-01-01
This paper proposes a new approach for variable selection in partially linear errors-in-variables (EV) models for longitudinal data by penalizing appropriate estimating functions.We apply the SCAD penalty to simultaneously select significant variables and estimate unknown parameters.The rate of convergence and the asymptotic normality of the resulting estimators are established.Furthermore,with proper choice of regularization parameters,we show that the proposed estimators perform as well as the oracle procedure.A new algorithm is proposed for solving penalized estimating equation.The asymptotic results are augmented by a simulation study.
A method for linearizing a nonlinear system with six state variables and three control variables
Hsia, W. S.
1986-01-01
A nonlinear system governed by x = f(x,u) with six state variables and three control variables is considered in this project. A set of transformations from (x,u) - space to (z,v) - space is defined such that the linear tangent model is independent of the operating point in the z-space. Therefore, it is possible to design a control law satisfying all operating points in the transformed space. An algorithm to construct the above transformations and to obtain the associated linearized system is described in this report. This method is applied to a rigid body using pole placement for the control law. Results are verified by numerical simulation. Closed loop poles in x-space using traditional local linearization are compared with those pole placements in the z-space.
A Simple Linear Ranking Algorithm Using Query Dependent Intercept Variables
Ailon, Nir
2008-01-01
The LETOR website contains three information retrieval datasets used as a benchmark for testing machine learning ideas for ranking. Algorithms participating in the challenge are required to assign score values to search results for a collection of queries, and are measured using standard IR ranking measures (NDCG, precision, MAP) that depend only the relative score-induced order of the results. Similarly to many of the ideas proposed in the participating algorithms, we train a linear classifier. In contrast with other participating algorithms, we define an additional free variable (intercept, or benchmark) for each query. This allows expressing the fact that results for different queries are incomparable for the purpose of determining relevance. The cost of this idea is the addition of relatively few nuisance parameters. Our approach is simple, and we used a standard logistic regression library to test it. The results beat the reported participating algorithms. Hence, it seems promising to combine our approac...
EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES
Palaversa, Lovro; Eyer, Laurent; Rimoldini, Lorenzo [Observatoire Astronomique de l' Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Ivezić, Željko; Loebman, Sarah; Hunt-Walker, Nicholas; VanderPlas, Jacob; Westman, David; Becker, Andrew C. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States); Ruždjak, Domagoj; Sudar, Davor; Božić, Hrvoje [Hvar Observatory, Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Galin, Mario [Faculty of Geodesy, Kačićeva 26, 10000 Zagreb (Croatia); Kroflin, Andrea; Mesarić, Martina; Munk, Petra; Vrbanec, Dijana [Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb (Croatia); Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States); Srdoč, Gregor, E-mail: lovro.palaversa@unige.ch [Saršoni 90, 51216 Viškovo (Croatia); and others
2013-10-01
We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg{sup 2} of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the
EXPLORING THE VARIABLE SKY WITH LINEAR. III. CLASSIFICATION OF PERIODIC LIGHT CURVES
We describe the construction of a highly reliable sample of ∼7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10,000 deg2 of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ∼0.03 mag at r = 15 to ∼0.20 mag at r = 18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ∼200,000 most probable candidate variables with r < 17 and visually confirmed and classified ∼7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars (β Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median
ENVIRONMENTAL ATTITUDES OF BIOLOGY TEACHER CANDIDATES AND THE ASSESSMENTS IN TERMS OF SOME VARIABLES
UĞULU, İlker; ERKOL, Sevilay
2013-01-01
Studying individuals and students' attitudes towards environment and factors affecting students to be responsible individuals towards their environment may provide help towards the solution of environmental problems. In this study, it is aimed to evaluate environmental attitudes of biology teacher candidates in terms of some variables. As a means of data collection, Environmental Attitude Scale and the personal information form have been used. Environmental Attitude Scale which has 35 items i...
Antoniucci, S.; Giannini, T.; Li Causi, G.; Lorenzetti, D., E-mail: simone.antoniucci@oa-roma.inaf.it, E-mail: teresa.giannini@oa-roma.inaf.it, E-mail: gianluca.licausi@oa-roma.inaf.it, E-mail: dario.lorenzetti@oa-roma.inaf.it [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio (Italy)
2014-02-10
Aiming to statistically study the variability in the mid-IR of young stellar objects, we have compared the 3.6, 4.5, and 24 μm Spitzer fluxes of 1478 sources belonging to the C2D (Cores to Disks) legacy program with the WISE fluxes at 3.4, 4.6, and 22 μm. From this comparison, we have selected a robust sample of 34 variable sources. Their variations were classified per spectral Class (according to the widely accepted scheme of Class I/flat/II/III protostars), and per star forming region. On average, the number of variable sources decreases with increasing Class and is definitely higher in Perseus and Ophiuchus than in Chamaeleon and Lupus. According to the paradigm Class ≡ Evolution, the photometric variability can be considered to be a feature more pronounced in less evolved protostars, and, as such, related to accretion processes. Moreover, our statistical findings agree with the current knowledge of star formation activity in different regions. The 34 selected variables were further investigated for similarities with known young eruptive variables, namely the EXors. In particular, we analyzed (1) the shape of the spectral energy distribution, (2) the IR excess over the stellar photosphere, (3) magnitude versus color variations, and (4) output parameters of model fitting. This first systematic search for EXors ends up with 11 bona fide candidates that can be considered as suitable targets for monitoring or future investigations.
Rotational properties of the Haumea family members and candidates: Short-term variability
Thirouin, Audrey; Noll, Keith S; Moskovitz, Nicholas A; Ortiz, Jose-Luis; Doressoundiram, Alain
2016-01-01
Haumea is one of the most interesting and intriguing transneptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than ten TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the transneptunian belt. Various models have been proposed but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members, and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27+/-1.19 h for the confirmed family members, 6.44+/-1.16 h for the candidates...
Fermi variability study of the candidate pulsar binary 2FGL J0523.3−2530
Xing, Y.; Wang, ZX; Ng, SCY
2014-01-01
The Fermi source 2FGL~J0523.3$-$2530 has recently been identified as a candidate millisecond pulsar binary with an orbital period of 16.5 hrs. We have carried out detailed studies of the source's emission properties by analyzing data taken with the Fermi Large Area Telescope in the 0.2--300 GeV energy range. Long-term, yearly variability from the source has been found, with a factor of 4 flux variations in 1--300 GeV. From spectral analysis, we find an extra spectral component at 2--3 GeV tha...
Generalized linear models for categorical and continuous limited dependent variables
Smithson, Michael
2013-01-01
Introduction and OverviewThe Nature of Limited Dependent VariablesOverview of GLMsEstimation Methods and Model EvaluationOrganization of This BookDiscrete VariablesBinary VariablesLogistic RegressionThe Binomial GLMEstimation Methods and IssuesAnalyses in R and StataExercisesNominal Polytomous VariablesMultinomial Logit ModelConditional Logit and Choice ModelsMultinomial Processing Tree ModelsEstimation Methods and Model EvaluationAnalyses in R and StataExercisesOrdinal Categorical VariablesModeling Ordinal Variables: Common Practice versus Best PracticeOrdinal Model AlternativesCumulative Mod
Mustafa İLHAN
2012-06-01
Full Text Available This research aims to investigate geometric thinking levels of candidate mathematics teachers of primary and secondary schools in terms of various variables. The participants of the study consist of candidate primary and secondary school mathematics teachers studying at Dicle University in spring semester of 2010 – 2011 academic year. In collection of data, the geometric thinking test developed by Usiskin (1982 was used. According to research findings, most of the candidate primary and secondary school mathematics teachers couldn’t reach the required geometric thinking level. There weren’t any meaningful difference between geometric thinking levels of candidate primary and secondary school mathematics teachers. Geometric thinking levels of candidate primary and secondary school mathematics teachers showed a significant difference in terms of class variable, while they didn’t differ significantly in terms of gender and type of graduated high school variables.
Rotation Periods, Variability Properties and Ages for Kepler Exoplanet Candidate Host Stars
Walkowicz, Lucianne M
2013-01-01
We report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. We use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line-of-sight, and find a number of systems with possible spin-orbit misalignment. We additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.
The (non-)variability of magnetic chemically peculiar candidates in the Large Magellanic Cloud
Paunzen, E; Poleski, R; Krticka, J; Netopil, M; Zejda, M
2013-01-01
The galactic magnetic chemically peculiar (mCP) stars of the upper main sequence are well known as periodic spectral and light variables. The observed variability is obviously caused by the uneven distribution of overabundant chemical elements on the surfaces of rigidly rotating stars. The mechanism causing the clustering of some chemical elements into disparate structures on mCP stars has not been fully understood up to now. The observations of light changes of mCP candidates recently revealed in the nearby Large Magellanic Cloud (LMC) should provide us with information about their rotational periods and about the distribution of optically active elements on mCP stars born in other galaxies. We queried for photometry at the Optical Gravitational Lensing Experiment (OGLE)-III survey of published mCP candidates selected because of the presence of the characteristic 5200A flux depression. In total, the intersection of both sources resulted in twelve stars. We performed our own and standard periodogram time seri...
Rotational Properties of the Haumea Family Members and Candidates: Short-term Variability.
Thirouin, Audrey; Sheppard, Scott S.; Noll, Keith S.; Moskovitz, Nicholas A.; Ortiz, Jose Luis; Doressoundiram, Alain
2016-06-01
Haumea is one of the most interesting and intriguing trans-Neptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than 10 TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the trans-Neptunian belt. Various models have been proposed, but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27 ± 1.19 hr for the confirmed family members, 6.44 ± 1.16 hr for the candidates, and 7.65 ± 0.54 hr for other TNOs (without relation to the family). According to our study, there is a possibility that Haumea family members rotate faster than other TNOs; however, the sample of family members is still too limited for a secure conclusion. We also highlight the fast rotation of 2002 GH32. This object has a 0.36 ± 0.02 mag amplitude lightcurve and a rotational period of about 3.98 hr. Assuming 2002 GH32 is a triaxial object in hydrostatic equilibrium, we derive a lower limit to the density of 2.56 g cm‑3. This density is similar to Haumea’s and much more dense than other small TNO densities.
SUPPORTING STUDENTS’ UNDERSTANDING OF LINEAR EQUATIONS WITH ONE VARIABLE USING ALGEBRA TILES
Sari Saraswati; Ratu Ilma Indra Putri; Somakim
2016-01-01
This research aimed to describe how algebra tiles can support students’ understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students use the algebra tiles to find a method to solve linear equations with one variable. Design research was used as an approach in this study. It ...
The Classical Linear Regression Model with one Incomplete Binary Variable
Toutenburg, Helge; Nittner, T.
1999-01-01
We present three different methods based on the conditional mean imputation when binary explanatory variables are incomplete. Apart from the single imputation and multiple imputation especially the so-called pi imputation is presented as a new procedure. Seven procedures are compared in a simulation experiment when missing data are confined to one independent binary variable: complete case analysis, zero order regression, categorical zero order regression, pi imputation, single imputation, mu...
Supporting Students' Understanding of Linear Equations with One Variable Using Algebra Tiles
Saraswati, Sari; Putri, Ratu Ilma Indra; Somakim
2016-01-01
This research aimed to describe how algebra tiles can support students' understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students…
Short- and long-term variations in non-linear dynamics of heart rate variability
Kanters, J K; Højgaard, M V; Agner, E;
1996-01-01
rate and describes mainly linear correlations. Non-linear predictability is correlated with heart rate variability measured as the standard deviation of the R-R intervals and the respiratory activity expressed as power of the high-frequency band. The dynamics of heart rate variability changes suddenly......OBJECTIVES: The purpose of the study was to investigate the short- and long-term variations in the non-linear dynamics of heart rate variability, and to determine the relationships between conventional time and frequency domain methods and the newer non-linear methods of characterizing heart rate...... variability. METHODS: Twelve healthy subjects were investigated by 3-h ambulatory ECG recordings repeated on 3 separate days. Correlation dimension, non-linear predictability, mean heart rate, and heart rate variability in the time and frequency domains were measured and compared with the results from...
Interpreting Multiple Linear Regression: A Guidebook of Variable Importance
Nathans, Laura L.; Oswald, Frederick L.; Nimon, Kim
2012-01-01
Multiple regression (MR) analyses are commonly employed in social science fields. It is also common for interpretation of results to typically reflect overreliance on beta weights, often resulting in very limited interpretations of variable importance. It appears that few researchers employ other methods to obtain a fuller understanding of what…
The Central Star Candidate of the Planetary Nebula Sh2-71: Photometric and Spectroscopic Variability
Močnik, Teo; Pollacco, Don; Street, Rachel A
2015-01-01
We present the analysis of several newly obtained and archived photometric and spectroscopic datasets of the intriguing and yet poorly understood 13.5-mag central star candidate of the bipolar planetary nebula Sh2-71. Photometric observations confirmed the previously determined quasi-sinusoidal lightcurve with a period of 68 days and also indicated periodic sharp brightness dips, possibly eclipses, with a period of 17.2 days. In addition, the comparison between U and V lightcurves revealed that the 68-day brightness variations are accompanied by a variable reddening effect of $\\Delta E(U-V)=0.38$. Spectroscopic datasets demonstrated pronounced variations in spectral profiles of Balmer, helium and singly ionised metal lines and indicated that these variations occur on a time-scale of a few days. The most accurate verification to date revealed that spectral variability is not correlated with the 68-day brightness variations. The mean radial velocity of the observed star was measured to be $\\sim$26 km/s with an ...
Discovery of two new Galactic candidate luminous blue variables with WISE
Gvaramadze, V V; Miroshnichenko, A S; Berdnikov, L N; Langer, N; Stringfellow, G S; Todt, H; Hamann, W -R; Grebel, E K; Buckley, D; Crause, L; Crawford, S; Gulbis, A; Hettlage, C; Hooper, E; Husser, T -O; Kotze, P; Loaring, N; Nordsieck, K H; O'Donoghue, D; Pickering, T; Potter, S; Colmenero, E Romero; Vaisanen, P; Williams, T; Wolf, M; Reichart, D E; Ivarsen, K M; Haislip, J B; Nysewander, M C; LaCluyze, A P
2012-01-01
We report the discovery of two new Galactic candidate luminous blue variable (cLBV) stars via detection of circular shells (typical of known confirmed and cLBVs) and follow-up spectroscopy of their central stars. The shells were detected at 22 um in the archival data of the Mid-Infrared All Sky Survey carried out with the Wide-field Infrared Survey Explorer (WISE). Follow-up optical spectroscopy of the central stars of the shells conducted with the renewed Southern African Large Telescope (SALT) showed that their spectra are very similar to those of the well-known LBVs P Cygni and AG Car, and the recently discovered cLBV MN112, which implies the LBV classification for these stars as well. The LBV classification of both stars is supported by detection of their significant photometric variability: one of them brightened in the R- and I-bands by 0.68\\pm0.10 mag and 0.61\\pm0.04 mag, respectively, during the last 13-18 years, while the second one (known as Hen 3-1383) varies its B,V,R,I and K_s brightnesses by \\si...
Variable Selection for Marginal Longitudinal Generalized Linear Models
Eva Cantoni; Joanna Mills Flemming; Elvezio Ronchetti
2003-01-01
Variable selection is an essential part of any statistical analysis and yet has been somewhat neglected in the context of longitudinal data analysis. In this paper we propose a generalized version of Mallows's Cp (GCp) suitable for use with both parametric and nonparametric models. GCp provides an estimate of a measure of model's adequacy for prediction. We examine its performance with popular marginal longitudinal models (fitted using GEE) and contrast results with what is typically done in ...
Peixin ZHAO
2013-01-01
In this paper,we consider the variable selection for the parametric components of varying coefficient partially linear models with censored data.By constructing a penalized auxiliary vector ingeniously,we propose an empirical likelihood based variable selection procedure,and show that it is consistent and satisfies the sparsity.The simulation studies show that the proposed variable selection method is workable.
Branched–linear polyion complexes at variable charge densities
Structural behavior of complexes formed by a charged and branched copolymer and an oppositely charged and linear polyion was examined by Monte Carlo simulations employing a coarse-grained bead–spring model. The fractional bead charge and the branching density were systematically varied; the former between 0e and 1e and the latter such that both the comb-polymer and the bottle-brush limits were included. The number of beads of the main chain of the branched copolymer and of the linear polyion was always kept constant and equal, and a single side-chain length was used. Our analysis involved characterization of the complex as well as investigation of size, shape, and flexibility of the charged moieties. An interplay between Coulomb interaction and side-chain repulsion governed the structure of the polyion complex. At strong Coulomb interaction, the complexes underwent a gradual transition from a globular structure at low branching density to an extended one at high branching density. As the electrostatic coupling was decreased, the transition was smoothened and shifted to lower branching density, and, eventually, a behavior similar to that found for neutral branched polymer was observed. Structural analogies and dissimilarities with uncharged branched polymers in poor solutions are discussed. (paper)
Admissibilities of linear estimator in a class of linear models with a multivariate t error variable
无
2010-01-01
This paper discusses admissibilities of estimators in a class of linear models,which include the following common models:the univariate and multivariate linear models,the growth curve model,the extended growth curve model,the seemingly unrelated regression equations,the variance components model,and so on.It is proved that admissible estimators of functions of the regression coefficient β in the class of linear models with multivariate t error terms,called as Model II,are also ones in the case that error terms have multivariate normal distribution under a strictly convex loss function or a matrix loss function.It is also proved under Model II that the usual estimators of β are admissible for p 2 with a quadratic loss function,and are admissible for any p with a matrix loss function,where p is the dimension of β.
WenJun Zhang
2015-09-01
Full Text Available An ecological network can be constructed by calculating the sampling data of taxon by sample type. A statistically significant Pearson linear correlation means an indirect or direct linear interaction between two taxa, and a statistically significant partial correlation based on Pearson linear correlation, due to elimination of indirect effects of other taxa, means a candidate direct interaction between two taxa. People always use Pearson linear correlation to find interactions. However, some undeterministic interactions may be found and some candidate direct interactions may be missed when using this method. The results show that partial linear correlation (y is approximately half of the Pearson linear correlation (x (y=-0.0064+0.4785x, r2=0.173, p is less than 0.00001, n=1447, which means that indirect interactions increase mean interaction strength of taxa in the network. In all predicted interactions by partial linear correlation, about 34.35 percent (x, 0-100 percent (i.e., one-third of them are not successfully detected by linear correlation. In all predicted interactions by Pearson linear correlation, 50.58 percent (y, 0-100 percent (i.e., half of them are undeterministic interactions, i.e., not successfully detected by partial linear correlation, and 49.42 percent (z, 0-100 percent (i.e., half of them are candidate direct interactions, i.e., successfully detected by partial linear correlation also. The proportion of missed (x, mis-predicted (y and precisely predicted candidate direct interactions (z by Pearson linear correlation analysis decreases (r=-0.49, p=0.07, increases (r=0.48, p=0.08, and decreases (r=-0.48, p=0.08 slightly with the number of taxa (m respectively. Results show that the precisely predicted (z candidate direct interactions by Pearson linear correlation analysis are not necessarily those with the highest Pearson linear correlations. We should not try to choose a portion (e.g., 49.42 percent (z of predicted
A linearly expanding universe with variable G and $\\Lambda$
Arbab, A I
1999-01-01
We have studied a cosmological model with a cosmological term of the form linearly with time for both radiation and matter dominated epochs. The cosmological constant is found to decrease as $t^{-2}$ and the rate of particle creation is smaller than the Steady State value. The model gives present age of the universe $(\\rm t_p$) is found to be $\\rm t_p=H_p^{-1}$, where $\\rm H_p$ is the Hubble constant. The model is free from the main problems of the Standard Model. Since the scale factor $\\rm R\\propto t$ during the entire evolution of the universe the ratio of the cosmological constant at the Planck and present time is $\\rm\\fr{\\Lambda_{Pl}}{\\Lambda_p}=10^{120}$. This decay law justifies why, today, the cosmological constant is exceedingly small.
Non-linear variability in geophysics scaling and fractals
Lovejoy, S
1991-01-01
consequences of broken symmetry -here parity-is studied. In this model, turbulence is dominated by a hierarchy of helical (corkscrew) structures. The authors stress the unique features of such pseudo-scalar cascades as well as the extreme nature of the resulting (intermittent) fluctuations. Intermittent turbulent cascades was also the theme of a paper by us in which we show that universality classes exist for continuous cascades (in which an infinite number of cascade steps occur over a finite range of scales). This result is the multiplicative analogue of the familiar central limit theorem for the addition of random variables. Finally, an interesting paper by Pasmanter investigates the scaling associated with anomolous diffusion in a chaotic tidal basin model involving a small number of degrees of freedom. Although the statistical literature is replete with techniques for dealing with those random processes characterized by both exponentially decaying (non-scaling) autocorrelations and exponentially decaying...
The linear system theory's account of behavior maintained by variable-ratio schedules.
McDowell, J. J; Wixted, J T
1988-01-01
The mathematical theory of linear systems, which has been used successfully to describe behavior maintained by variable-interval schedules, is extended to describe behavior maintained by variable-ratio schedules. The result of the analysis is a pair of equations, one of which expresses response rate on a variable-ratio schedule as a function of the mean ratio requirement (n) that the schedule arranges. The other equation expresses response rate on a variable-ratio schedule as a function of re...
WenJun Zhang; Xin Li
2015-01-01
An ecological network can be constructed by calculating the sampling data of taxon by sample type. A statistically significant Pearson linear correlation means an indirect or direct linear interaction between two taxa, and a statistically significant partial correlation based on Pearson linear correlation, due to elimination of indirect effects of other taxa, means a candidate direct interaction between two taxa. People always use Pearson linear correlation to find interactions. However, some...
Hundreds of new cluster candidates in the VISTA variables in the Via Lactea survey DR1
Barba, R H; Castellon, J L Nilo; Firpo, V; Minniti, D; Lucas, P; Emerson, J P; Hempel, M; Soto, M; Saito, R K
2015-01-01
VISTA variables in the Via Lactea is an ESO Public survey dedicated to scan the bulge and an adjacent portion of the Galactic disk in the fourth quadrant using the VISTA telescope and the near-infrared camera VIRCAM. One of the leading goals of the VVV survey is to contribute to the knowledge of the star cluster population of the Milky Way. To improve the census of the Galactic star clusters, we performed a systematic scan of the JHKs images of the Galactic plane section of the VVV survey. Our detection procedure is based on a combination of superficial density maps and visual inspection of promising features in the NIR images. The material examined are color-composite images corresponding to the DR1 of VVV. We report the discovery of 493 new star cluster candidates. The analysis of the spatial distribution show that the clusters are very concentrated in he Galactic plane, presenting some local maxima around the position of large star-forming complexes, such as G305, RCW 95, and RCW 106. The vast majority of ...
Possible candidates for multiple occurrence of variable stars in the VSX catalogue
Liska, Jiri; Auer, Reinhold Friedrich; Prudil, Zdenek; Juranova, Anna
2015-01-01
A paper about variable stars with possible multiple occurrence in the VSX catalogue is presented. Our main criteria for identification of such duplicities were the angular distance among stars (below 1 arcmin) and close periods of objects. In our approach, we also considered double or half values of periods to reveal possible misclassification among stars with similar light curve shapes. The probability of false identification is expressed by the parameter R giving the relative difference between periods. We found 1487 pairs of stars in angular distance lower than 1 arcmin with period difference R lower than 0.1 %, which are high-probable candidates on duplicates. From this sample, 354 pairs have exactly the same periods (R = 0.0 %) and should be considered as definite duplicates. The main contribution of certain duplicates comes from the Catalina Sky Survey (73 pairs have two names with CSS acronym) and from the BEST projects (71 pairs). Distribution of identified duplicates on the sky is not homogeneous but...
Selection of AGN candidates in the GOODS-South Field through SPITZER/MIPS 24 microns variability
García-González, Judit; Alonso-Herrero, Almudena; Pérez-González, Pablo G.; Hernán-Caballero, Antonio; Sarajedini, Vicki L.; Villar, Víctor
2014-01-01
We present a study of galaxies showing mid-infrared variability in the deepest Spitzer/MIPS 24 $\\mu$m surveys in the GOODS-South field. We divide the dataset in epochs and subepochs to study the long-term (months-years) and the short-term (days) variability. We use a $\\chi^2$-statistics method to select AGN candidates with a probability $\\leq$ 1% that the observed variability is due to statistical errors alone. We find 39 (1.7% of the parent sample) sources that show long-term variability and...
SUPPORTING STUDENTS’ UNDERSTANDING OF LINEAR EQUATIONS WITH ONE VARIABLE USING ALGEBRA TILES
Sari Saraswati
2016-01-01
Full Text Available This research aimed to describe how algebra tiles can support students’ understanding of linear equations with one variable. This article is a part of a larger research on learning design of linear equations with one variable using algebra tiles combined with balancing method. Therefore, it will merely discuss one activity focused on how students use the algebra tiles to find a method to solve linear equations with one variable. Design research was used as an approach in this study. It consists of three phases, namely preliminary design, teaching experiment and retrospective analysis. Video registrations, students’ written works, pre-test, post-test, field notes, and interview are technic to collect data. The data were analyzed by comparing the hypothetical learning trajectory (HLT and the actual learning process. The result shows that algebra tiles could supports students’ understanding to find the formal solution of linear equation with one variable.
Selection of AGN candidates in the GOODS-South Field through Spitzer/MIPS 24 μm variability
García González, Judit; Alonso Herrero, Almudena; Pérez González, Pablo Guillermo; Hernán Caballero, Antonio; Sarajedini, Vicki L.; Villar, Victor
2015-01-01
We present a study of galaxies showing mid-infrared variability in data taken in the deepest Spitzer/MIPS 24 mu m surveys in the Great Observatory Origins Deep Survey South field. We divide the data set in epochs and subepochs to study the long-term (months-years) and the short-term (days) variability. We use a chi^(2)-statistics method to select active galactic nucleus (AGN) candidates with a probability
Central limit theorems for directional and linear random variables with applications
García-Portugués, Eduardo; Crujeiras, Rosa M.; González-Manteiga, Wenceslao
2014-01-01
A central limit theorem for the integrated squared error of the directional-linear kernel density estimator is established. The result enables the construction and analysis of two testing procedures based on squared loss: a nonparametric independence test for directional and linear random variables and a goodness-of-fit test for parametric families of directional-linear densities. Limit distributions for both test statistics, and a consistent bootstrap strategy for the goodness-of-fit test, a...
Tanev, George; Saadi, Dorthe Bodholt; Hoppe, Karsten;
2014-01-01
Chronic stress detection is an important factor in predicting and reducing the risk of cardiovascular disease. This work is a pilot study with a focus on developing a method for detecting short-term psychophysiological changes through heart rate variability (HRV) features. The purpose of this pilot...... features. Standardizing non-linear HRV features for each subject was found to be an important factor for the improvement of the classification results....
Erdogan, Ahmet
2010-01-01
Based on Social Cognitive Carier Theory (SCCT) (Lent, Brown, & Hackett, 1994, 2002), this study tested the effects of mathematics teacher candidates' self-efficacy in, outcome expectations from, and interest in CAME on their intentions to integrate Computer-Assisted Mathematics Education (CAME). While mathematics teacher candidates' outcome…
A linear structural equation approach to cross-sectional models with lagged variables
Folmer, H.; Knaap, G.A. van der
1981-01-01
Lagged variables play an important role in cross-sectional models in geography and regional sciences. This paper starts with an overview of the situations in which they may be required. Lagged variables also pose serious problems from a statistical point of view: multicollinearity and the determination of the length of the lag. Some common approaches to these two problems are discussed and evaluated.As an alternative a linear structural equation approach is presented, where the lagged variabl...
High-Dimensional Non-Linear Variable Selection through Hierarchical Kernel Learning
Bach, Francis
2009-01-01
We consider the problem of high-dimensional non-linear variable selection for supervised learning. Our approach is based on performing linear selection among exponentially many appropriately defined positive definite kernels that characterize non-linear interactions between the original variables. To select efficiently from these many kernels, we use the natural hierarchical structure of the problem to extend the multiple kernel learning framework to kernels that can be embedded in a directed acyclic graph; we show that it is then possible to perform kernel selection through a graph-adapted sparsity-inducing norm, in polynomial time in the number of selected kernels. Moreover, we study the consistency of variable selection in high-dimensional settings, showing that under certain assumptions, our regularization framework allows a number of irrelevant variables which is exponential in the number of observations. Our simulations on synthetic datasets and datasets from the UCI repository show state-of-the-art pre...
Sammer, G
1998-05-01
In the investigation of heart rate and heart rate variability, the discrimination between mental workload, physical activity and respiration is known to be methodologically difficult. At most, heart rate variability measures are more likely to be coarse-grained measures with variability confounded by heart rate. Moreover, the spectral analysis of heart rate variability shows broad-band frequency characteristics, pointing towards non-stationarity or non-linearity. From this it is suggested to focus on non-linear dynamic analyses that are variance-insensitive. The experimental section of the paper focuses on the estimation of two non-linear measures for both heartbeat dynamics and respiration, the correlation dimension indicating complexity and the Lyapunov exponents indicating predictability. The results indicate that the complexity of heart dynamics is related to the type of task and that the predictability of heart dynamics is related to the amount of load. PMID:9613233
Johnson, J.
2016-06-01
(Abstract only) A spreadsheet of 3,548 automatically classified candidate Cepheid variable stars from the ASAS (All Sky Automated Survey) photometry data was provided to AAVSO (American Association of Variable Star Observers) members for analysis. It was known that the computer filters had significantly overpopulated the list. Patrick Wils originally investigated a small subset of the data using 2MASS, PPMXL, and ROTSE data, and discovered that the vast majority of the 84 candidates he surveyed appeared to have been misidentified, demonstrating the need to reclassify these variables. The most common misidentification seemed to be of BY Draconis stars (K and M spotted dwarfs), which led to an ongoing project to systematically identify BY Draconis stars from this data set. The stars are sorted using the International Variable Star Index (VSX) information and ASAS light curves to search for prior reclassification by other authors in the time since the initial population of the candidate list (e.g. using ROTSE data), along with infrared photometry (2MASS) and proper motion (PPMXL) data. An analysis of light curves and phase plots using the AAVSO software vstar is the final step in identifying potential BY Draconis stars. The goal of this project has been to submit updated identifications for these stars to VSX. This final presentation on this project will identify the last set of reclassified BY Draconis stars and discuss future directions for this research.
Pei Xin ZHAO; Liu Gen XUE
2011-01-01
In this paper,we present a variable selection procedure by combining basis function approximations with penalized estimating equations for semiparametric varying-coefficient partially linear models with missing response at random.The proposed procedure simultaneously selects significant variables in parametric components and nonparametric components.With appropriate selection of the tuning parameters,we establish the consistency of the variable selection procedure and the convergence rate of the regularized estimators.A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.
Some Properties of A Lack-of-Fit Test for a Linear Errors in Variables Model
Li-xing Zhu; Heng-jian Cui; K.W.Ng
2004-01-01
The relationship between the linear errors-in-variables model and the corresponding ordinary linear model in statistical inference is studied.It is shown that normality of the distribution of covariate is a necessary and su cient condition for the equivalence.Therefore,testing for lack-of-t in linear errors-in-variables model can be converted into testing for it in the corresponding ordinary linear model under normality assumption.A test of score type is constructed and the limiting chi-squared distribution is derived under the null hypothesis.Furthermore,we discuss the power of the test and the choice of the weight function involved in the test statistic.
küçükosmanoğlu, hayrettin onur
2013-01-01
The purpose of this study to evaluate the levels of the music teacher candidates Self-Esteem by socio-demographic variables. Literature was reviewed, "Personal Information Form" and the "Rosenberg Self-Esteem Scale" used in order to obtain research data. For the purposes of this study, statistical analysis of the findings are presented in the tables. The study group of said research encompasses 101 undergraduates studying in Necmettin Erbakan University, Department of Fine Arts Education, a...
Variable Selection for Generalized Linear Mixed Models by L1-Penalized Estimation
Groll, Andreas
2011-01-01
Generalized linear mixed models are a widely used tool for modeling longitudinal data. However, their use is typically restricted to few covariates, because the presence of many predictors yields unstable estimates. The presented approach to the fitting of generalized linear mixed models includes an L1-penalty term that enforces variable selection and shrinkage simultaneously. A gradient ascent algorithm is proposed that allows to maximize the penalized loglikelihood yielding models with r...
Approximation of Functions of Two Variables by Certain Linear Positive Operators
Fatma Taşdelen; Ali Olgun; Gülen Bascanbaz-Tunca
2007-08-01
We introduce certain linear positive operators and study some approximation properties of these operators in the space of functions, continuous on a compact set, of two variables. We also find the order of this approximation by using modulus of continuity. Moreover we define an th order generalization of these operators and observe its approximation properties. Furthermore, we study the convergence of the linear positive operators in a weighted space of functions of two variables and find the rate of this convergence using weighted modulus of continuity.
Buscha, Franz; Conte, Anna
2013-01-01
This paper examines the consequences of introducing a normally distributed effect into a system where the dependent variable is ordered and the explanatory variable is ordered and endogenous. Using simulation techniques we show that a naïve bivariate ordered probit estimator which fails to take a mixed effect into account will result in inconsistent estimates even when identification conditions are optimal. Our results suggest this finding only applies to non-linear endogenous systems.
Antoniucci, S; Causi, G Li; Lorenzetti, D
2014-01-01
Aiming at statistically studying the variability in the mid-IR of young stellar objects (YSOs), we have compared the 3.6, 4.5, and 24 um Spitzer fluxes of 1478 sources belonging to the C2D (Cores to Disks) legacy program with the WISE fluxes at 3.4, 4.6, and 22 um. From this comparison we have selected a robust sample of 34 variable sources. Their variations were classified per spectral Class (according to the widely accepted scheme of Class I/flat/II/III protostars), and per star forming region. On average, the number of variable sources decreases with increasing Class and is definitely higher in Perseus and Ophiuchus than in Chamaeleon and Lupus. According to the paradigm Class Evolution, the photometric variability can be considered to be a feature more pronounced in less evolved protostars, and, as such, related to accretion processes. Moreover, our statistical findings agree with the current knowledge of the star formation activity in different regions. The 34 selected variables were further investigate...
The Multifaceted Variable Approach: Selection of Method in Solving Simple Linear Equations
Tahir, Salma; Cavanagh, Michael
2010-01-01
This paper presents a comparison of the solution strategies used by two groups of Year 8 students as they solved linear equations. The experimental group studied algebra following a multifaceted variable approach, while the comparison group used a traditional approach. Students in the experimental group employed different solution strategies,…
Severe linear growth retardation in rural Zambian children: the influence of biological variables.
Hautvast, J.L.A.; Tolboom, J.J.M.; Kaftwembe, E.M.; Musonda, R.M.; Mwanakasale, V.; Staveren, W.A. van; Hof, M.A. van 't; Sauerwein, R.W.; Willems, J.L.; Monnens, L.A.H.
2000-01-01
BACKGROUND: The prevalence of stunting in preschool children in Zambia is high; stunting has detrimental effects on concurrent psychomotor development and later working capacity. OBJECTIVE: Our objective was to investigate biological variables that may contribute to linear growth retardation in pres
Vardanjan Gumedin Surenovich
2012-01-01
The functional similarity method applicable for the simulation of various physical processes is considered in the proposed paper. A solution to some linear differential equations with variable coefficients is provided. The aforementioned equations are widely used as part of solutions to problems of mechanics of deformable solid bodies.
The Practical Stability of the Linear Systems with the Phase Space Variable Measurability
SOPRONIUK, Y.
2007-04-01
Full Text Available For the linear transitional systems with the variable measurability of the phase space it was formulated and solved the problem about the practical stability. It was proved the theorem about the criteria of the practical stability, on the base of which it was developed the algorithm of the digital method of the search of the quality criteria of the practical stability.
Low voltage RF MEMS variable capacitor with linear C-V response
Elshurafa, Amro M.
2012-07-23
An RF MEMS variable capacitor, fabricated in the PolyMUMPS process and tuned electrostatically, possessing a linear capacitance-voltage response is reported. The measured quality factor of the device was 17 at 1GHz, while the tuning range was 1.2:1 and was achieved at an actuation DC voltage of 8V only. Further, the linear regression coefficient was 0.98. The variable capacitor was created such that it has both vertical and horizontal capacitances present. As the top suspended plate moves towards the bottom fixed plate, the vertical capacitance increases whereas the horizontal capacitance decreases simultaneously such that the sum of the two capacitances yields a linear capacitance-voltage relation. © 2012 The Institution of Engineering and Technology.
A linearly-acting variable-reluctance generator for thermoacoustic engines
Highlights: • A new design for a linear alternator for thermoacoustic power converters is presented. • A theoretical and semi-empirical model of the generator is developed and validated. • The variable-reluctance generator’s performance is experimentally characterized. • Scaling to higher frequency suggests efficient operation with thermoacoustic engines. - Abstract: A crucial element in a thermoacoustic power converter for reliable small-scale power generation applications is an efficient acoustic-to-electric energy converter. In this work, an acoustic-to-electric transducer for application with a back-to-back standing wave thermoacoustic engine, based on a linearly-acting variable-reluctance generator is proposed, built and experimentally tested. Static and dynamic experiments are performed on one side of the generator on a shaker table at 60 Hz with 5 mm peak-to-peak displacement for performance characterization. A theoretical and empirical model of the variable-reluctance generator are presented and validated with experimental data. A frequency scaling based on the empirical model indicates that a maximum power output of 84 W at 78% generator efficiency is feasible at the thermoacoustic engine’s operating frequency of 250 Hz, not considering power electronic losses. This suggests that the linearly-acting variable-reluctance generator can efficiently convert high frequency small amplitude acoustic oscillations to useful electricity and thus enables its integration into a thermoacoustic power converter
A strain-tunable nanoimprint lithography for linear variable photonic crystal filters
Liu, Longju; Khan, Haris A.; Li, Jingjing; Hillier, Andrew C.; Lu, Meng
2016-07-01
This paper presents the fabrication methodology of a linear variable photonic crystal (PC) filter with narrowband reflection that varies over a broad spectral range along the length of the filter. The key component of the linear variable PC filter is a polymer surface-relief grating whose period changes linearly as a function of its position on the filter. The grating is fabricated using a nanoreplica molding process with a wedge-shaped elastomer mold. The top surface of the mold carries the grating pattern and the wedge is formed by a shallow angle between the top and bottom surfaces of the mold. During the replica molding process, a uniaxial force is applied to stretch the mold, resulting in a nearly linearly varying grating period. The period of the grating is determined using the magnitude of the force and the local thickness of the mold. The grating period of the fabricated device spans a range of 421.8–463.3 nm over a distance of 20 mm. A high refractive index dielectric film is deposited on the graded-period grating to act as the waveguide layer of the PC device. The resonance reflection feature of the device varies linearly in a range of 680.2–737.0 nm over the length of the grating.
Study of the luminous blue variable star candidate G26.47+0.02 and its environment
Paron, S.; Combi, J. A.; Petriella, A.; Giacani, E.
2012-01-01
The luminous blue variable (LBV) stars are peculiar very massive stars. The study of these stellar objects and their surroundings is important for understanding the evolution of massive stars and its effects on the interstellar medium. We study the LBV star candidate G26.47+0.02. Using several large-scale surveys in different frequencies we performed a multiwavelength study of G26.47+0.02 and its surroundings. We found a molecular shell (seen in the 13CO J=1-0 line) that partially surrounds t...
Noiseless Linear Amplifiers in Entanglement-Based Continuous-Variable Quantum Key Distribution
Yichen Zhang
2015-06-01
Full Text Available We propose a method to improve the performance of two entanglement-based continuous-variable quantum key distribution protocols using noiseless linear amplifiers. The two entanglement-based schemes consist of an entanglement distribution protocol with an untrusted source and an entanglement swapping protocol with an untrusted relay. Simulation results show that the noiseless linear amplifiers can improve the performance of these two protocols, in terms of maximal transmission distances, when we consider small amounts of entanglement, as typical in realistic setups.
OUTPUT VARIABLE STRUCTURE CONTROL FOR TIME-INVARIANT LINEAR TIME-DELAY SINGULAR SYSTEM
Jifeng GUO; Cunchen GAO
2007-01-01
Synthesis and design of output variable structure controller for time-invariant linear time-delay singular system are studied. In the case that the system is regular and the system index is one, switching function with integral compensator and variable structure controller are designed, which guarantee that the sliding mode is asymptotically stable and the solution trajectory of the system arrives at the switching manifold in limited time. The design method is applicable to the systems which can be regularized. Finally, a numerical example is given to demonstrate effectiveness and simplicity of the design method.
Zhang, Yichen; Yu, Song; Guo, Hong
2015-11-01
We propose a modified no-switching continuous-variable quantum key distribution protocol by employing a practical noiseless linear amplifier at the receiver to increase the maximal transmission distance and tolerable excess noise. A security analysis is presented to derive the secure bound of the protocol in presence of a Gaussian noisy lossy channel. Simulation results show that the modified protocol can not only transmit longer distance and tolerate more channel excess noise than the original protocol, but also distribute more secure keys in the enhanced region where we define a critical point to separate the enhanced and degenerative region. This critical point presents the condition of using a practical noiseless linear amplifier in the no-switching continuous-variable quantum cryptography, which is meaningful and instructive to implement a practical experiment.
Xuemei HU; Feng LIU; Zhizhong WANG
2009-01-01
The authors propose a V_(N,P) test statistic for testing finite-order serial correlation in a semiparametric varying coefficient partially linear errors-in-variables model. The test statistic is shown to have asymptotic normal distribution under the null hypothesis of no serial correlation. Some Monte Carlo experiments are conducted to examine the finite sample performance of the proposed V_(N,P) test statistic. Simulation results confirm that the proposed test performs satisfactorily in estimated size and power.
Linear differential equations with variable coefficients: Fundamental theorem of the solving kernel
The present work shows a new fundamental theorem concerning the explicit solution of a homogeneous or non-homogeneous linear differential equation of order n, with variable coefficients. In facts, the explicit solution of the mentioned equations is reduced to the knowledge of just one particular integral: the kernel of the homogeneous or of the associated homogeneous equation respectively. Because of its several and relevant consequences, the theorem has been properly named: fundamental theorem of the solving kernel
A Non-linear "Inflation-Relative Prices Variability" Relationship: Evidence from Latin America
Mª Ángeles Caraballo Pou; Carlos Dabús; Diego Caramuta
2006-01-01
This paper presents evidence on a non-linear "inflation-relative prices variability" relationship in three Latin American countries with very high inflation experiences: Argentina, Brazil and Peru. More precisely, and in contrast to results found in previous literature for similar countries, we find a non-concave relation at higher inflation regimes, i.e. when inflation rate surpasses certain threshold. This non-concavity is mainly explained by the unexpected component of inflation, which sug...
Non-linear and scale-invariant analysis of the Heart Rate Variability
Kalda, J; Vainu, M; Laan, M
2003-01-01
Human heart rate fluctuates in a complex and non-stationary manner. Elaborating efficient and adequate tools for the analysis of such signals has been a great challenge for the researchers during last decades. Here, an overview of the main research results in this field is given. The following question are addressed: (a) what are the intrinsic features of the heart rate variability signal; (b) what are the most promising non-linear measures, bearing in mind clinical diagnostic and prognostic applications.
Pellegrini, Claudio; Schroeder, Alexandre; Santini, Otavio; Vendrami, Carlos Eduardo; Lenzi, Arcanjo; Silva, Olavo
2014-01-01
The household appliances market noise levels requirements have rapidly increased in the last years. Despite the traditional approach for defining noise requirements focused on steady-state sound power levels, the transient noise is becoming a key factor in defining sound quality specification. Variable speed compressor technologies lead to a significant advantage on this aspect since in standard operation conditions the compressor runs at relatively low speeds for most of the time. Linear mot...
Hundreds of new cluster candidates in the VISTA Variables in the Vía Láctea survey DR1
Barbá, R. H.; Roman-Lopes, A.; Nilo Castellón, J. L.; Firpo, V.; Minniti, D.; Lucas, P.; Emerson, J. P.; Hempel, M.; Soto, M.; Saito, R. K.
2015-09-01
Context. VISTA variables in the Vía Láctea is an ESO Public survey dedicated to scanning the bulge and an adjacent portion of the Galactic disk in the fourth quadrant using the VISTA telescope and its near-infrared camera VIRCAM. One of the leading goals of the VVV survey is to contribute to knowledge of the star cluster population of the Milky Way. Aims: To improve the census of Galactic star clusters, we performed a systematic and careful scan of the JHKs images of the Galactic plane section of the VVV survey. Methods: Our detection procedure is based on a combination of stellar density maps and visual inspection of promising features in the J-, H-, and KS-band images. The material examined are VVV JHKS color-composite images corresponding to Data Release 1 of VVV. Results: We report the discovery of 493 new infrared star cluster candidates. The analysis of the spatial distribution show that the clusters are very concentrated in the Galactic plane, presenting some local maxima around the position of large star-forming complexes, such as G305, RCW 95, and RCW 106. The vast majority of the new star cluster candidates are quite compact and generally surrounded by bright and/or dark nebulosities. IRAS point sources are associated with 59% of the sample, while 88% are associated with MSX point sources. GLIMPSE 8 μm images of the cluster candidates show a variety of morphologies, with 292 clusters dominated by knotty sources, while 361 clusters show some kind of nebulosity in this wavelength regime. Spatial cross-correlation with young stellar objects, masers, and extended green-object catalogs suggest that a large sample of the new cluster candidates are extremely young. In particular, 104 star clusters associated with methanol masers are excellent candidates for ongoing massive star formation. Also, there is a special set of sixteen cluster candidates that present clear signposts of star-forming activity having associated simultaneosly dark nebulae, young stellar
Ebru Olcay KARABULUT
2009-12-01
Full Text Available The aim of this survey is; students’ studying in Physical Education and Sport Department of AEÜ and GÜ through problem solving test and to specify whether students differentiate according to independent variables obtained from personal variables and to reveal relation between students’ ability of problem solving. Totally, 304 students, whom were selected randomly among the students studying in Physical Education and Sport Department of AEÜ and GÜ voluntarily participated in this survey. In this survey, Personal Data Form and Problem Solving Inventory (PÇE were used as a means of data collection. The research indicated that the skills of problem solving and approaches of problem solving generally the university students is medium level. The average point of the sub-dimensions and its total of the skill of problem solving didn’t change in a meaningful level accordingly class and national but it changed in a meaningful level depending on the university, sex, branches of sports.
A Population of Short-Period Variable Quasars from PTF as Supermassive Black Hole Binary Candidates
Charisi, M; Haiman, Z; Price-Whelan, A M; Graham, M J; Bellm, E C; Laher, R R; Marka, S
2016-01-01
Supermassive black hole binaries (SMBHBs) at sub-parsec separations should be common in galactic nuclei, as a result of frequent galaxy mergers. Hydrodynamical simulations of circumbinary discs predict strong periodic modulation of the mass accretion rate on time-scales comparable to the orbital period of the binary. As a result, SMBHBs may be recognized by the periodic modulation of their brightness. We conducted a statistical search for periodic variability in a sample of 35,383 spectroscopically confirmed quasars in the photometric database of the Palomar Transient Factory (PTF). We analysed Lomb-Scargle periodograms and assessed the significance of our findings by modeling each individual quasar's variability as a damped random walk (DRW). We identified 50 quasars with significant periodicity beyond the DRW model, typically with short periods of a few hundred days. We find 33 of these to remain significant after a re-analysis of their periodograms including additional optical data from the intermediate-PT...
AKYEL, Yakup; YILMAZ, İdris
2008-01-01
Empathy is the process of setting yourself instead of someone else’s place and comprehending everything from his point of view, Understanding and feeling his senses and thoughts correctly and conveying this state to him. That’s why empathy appears to be a significant variable in educational activities. Especially, spreading the sporting activities into the society. Physical educators have high emphatic skills, emphatic lavels and their qualifications, research ability and production abilities...
Hundreds of new cluster candidates in the VISTA variables in the Via Lactea survey DR1
Barba, R. H.; Roman-Lopes, A.; Castellon, J. L. Nilo; Firpo, V.; Minniti, D.; Lucas, P.; Emerson, J.P.; Hempel, M.(Deutsches Elektronen-Synchrotron, Hamburg, Germany); Soto, M.; R. K. Saito
2015-01-01
VISTA variables in the Via Lactea is an ESO Public survey dedicated to scan the bulge and an adjacent portion of the Galactic disk in the fourth quadrant using the VISTA telescope and the near-infrared camera VIRCAM. One of the leading goals of the VVV survey is to contribute to the knowledge of the star cluster population of the Milky Way. To improve the census of the Galactic star clusters, we performed a systematic scan of the JHKs images of the Galactic plane section of the VVV survey. Ou...
Humphreys, Roberta M.; Davidson, Kris [Minnesota Institute for Astrophysics, 116 Church Street SE, University of Minnesota, Minneapolis, MN 55455 (United States); Weis, Kerstin; Bomans, D. J.; Burggraf, Birgitta, E-mail: roberta@umn.edu, E-mail: kweis@astro.rub.de [Astronomical Institute, Ruhr-Universitaet Bochum (Germany)
2014-07-20
An increasing number of non-terminal eruptions are being found in the numerous surveys for optical transients. Very little is known about these giant eruptions, their progenitors and their evolutionary state. A greatly improved census of the likely progenitor class, including the most luminous evolved stars, the luminous blue variables (LBVs), and the warm and cool hypergiants is now needed for a complete picture of the final pre-supernova stages of very massive stars. We have begun a survey of the evolved and unstable luminous star populations in several nearby resolved galaxies. In this second paper on M31 and M33, we review the spectral characteristics, spectral energy distributions, circumstellar ejecta, and evidence for mass loss for 82 luminous and variable stars. We show that many of these stars have warm circumstellar dust including several of the Fe II emission line stars, but conclude that the confirmed LBVs in M31 and M33 do not. The confirmed LBVs have relatively low wind speeds even in their hot, quiescent or visual minimum state compared to the B-type supergiants and Of/WN stars which they spectroscopically resemble. The nature of the Fe II emission line stars and their relation to the LBV state remains uncertain, but some have properties in common with the warm hypergiants and the sgB[e] stars. Several individual stars are discussed in detail. We identify three possible candidate LBVs and three additional post-red supergiant candidates. We suggest that M33-013406.63 (UIT301,B416) is not an LBV/S Dor variable, but is a very luminous late O-type supergiant and one of the most luminous stars or pair of stars in M33.
A variable ULX and possible IMBH candidate in M51a
Earnshaw, Hannah M.; Roberts, Timothy P.; Heil, Lucy M.; Mezcua, Mar; Walton, Dominic J.; Done, Chris; Harrison, Fiona A.; Lansbury, George B.; Middleton, Matthew J.; Sutton, Andrew D.
2016-03-01
Ultraluminous X-ray source (ULX)-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ULX, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analyse the source using archival data from XMM-Newton, Chandra and NuSTAR, and by examining optical and radio data from HST and Very Large Array. Our X-ray spectral analysis shows that the source has a hard power-law spectral shape with a photon index Γ ˜ 1.5, which persists despite the source's X-ray luminosity varying by over an order of magnitude. The power spectrum of the source features a break at 6.5^{+0.5}_{-1.1} × 10-3 Hz, from a low-frequency spectral index of α _1={-}0.1^{+0.5}_{-0.2} to a high-frequency spectral index of α _2=6.5^{+0.05}_{-0.14}, making it analogous to the low-frequency break found in the power spectra of low/hard state black holes (BHs). We can take a lower frequency limit for a corresponding high-frequency break to calculate a BH mass upper limit of 1.6 × 103 M⊙. Using the X-ray/radio Fundamental Plane, we calculate another upper limit to the BH mass of 3.5 × 104 M⊙ for a BH in the low/hard state. The hard spectrum, high rms variability and mass limits are consistent with ULX-7 being an intermediate-mass BH; however we cannot exclude other interpretations of this source's interesting behaviour, most notably a neutron star with an extreme accretion rate.
Genetic Variability of Argan Tree and Preselection of the Candidate Plus Trees
Naima AIT AABD
2010-12-01
Full Text Available Argan tree productivity shows a wide disparity in space and time, while the degraded forest areas show low growth and unproductive shrubs. Moreover, even if reforestation, currently led by various local actors (Waters and Forests, Agency of Social Development, Cooperatives and Associations of development experienced a technical improvement, the plants used do not meet any selection criteria. Generally, unknown origin seedlings are used in reforestation and good seedlings are not reproduced. In this context, this study investigates through a choice of pilot sites the characterization in-situ of populations and/or argan trees with two selection criteria related to fruit: facility of crushing and oil content. For this purpose, and with the support of local population, the identification of performance trees, prospection and collection of fruits were realized in various sites representing five principal provinces of argan trees area (Essaouira; Taroudante; Agadir Ida Outanane; Chtouka-Ait Baha and Tiznit. Within each provenance, measurements related to 6750 fruits and the morphometric data were subjected to the analysis of the variance, according to the general linear model, where the genotype factor (mother tree is hierarchical to provenance factor. This study offers preliminary information for the development of a breeding population and allows us to make a first selection of trees, having a clear superiority relating to the characters related to the production of oil and the facility of crushing seeds. At the present moment there is a genetic base large enough to initiate a breeding program.
Charisi, Maria; Haiman, Zoltán; Price-Whelan, Adrian M; Márka, Szabolcs
2015-01-01
Graham et al. (2015) discovered a supermassive black hole binary (SMBHB) candidate and identified the detected 5.2 yr period of the optical variability as the orbital period of the binary. Hydrodynamical simulations predict multiple periodic components for the variability of SMBHBs, thus raising the possibility that the true period of the binary is different from 5.2 yr. We analyse the periodogram of PG1302 and find no compelling evidence for additional peaks. We derive upper limits on any additional periodic modulations in the available data, by modeling the light-curve as the sum of red noise and the known 5.2 yr periodic component, and injecting additional sinusoidal signals. We find that, with the current data, we would be able to detect with high significance (false alarm probability <1%) secondary periodic terms with periods in the range predicted by the simulations, if the amplitude of the variability was at least ~0.07 mag (compared to 0.14 mag for the main peak). A three-year follow-up monitoring ...
A variable ULX and possible IMBH candidate in M51a
Earnshaw, Hannah M; Heil, Lucy M; Mezcua, Mar; Walton, Dominic J; Done, Chris; Harrison, Fiona A; Lansbury, George B; Middleton, Matthew J; Sutton, Andrew D
2015-01-01
ULX-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ultraluminous X-ray source, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analyse the source using archival data from XMM-Newton, Chandra and NuSTAR, and by examining optical and radio data from HST and VLA. Our X-ray spectral analysis shows that the source has a hard power-law spectral shape with a photon index Gamma~1.5, which persists despite the source's X-ray luminosity varying by over an order of magnitude. The power spectrum of the source features a break at ~7x10^-3 Hz, from a low-frequency spectral index of alpha_1=0.1^{+0.2}_{-0.1} to a high-frequency spectral index of alpha_2=0.7^{+0.1}_{-0.3}, making it analogous to the low-frequency break found in the power spectra of low/hard state black holes (BHs). We can take a lower frequency limit for a corresponding high-frequency break to calculate a BH mass upper limit of 1.6x10^3 solar masse...
Elena Sarabia Cachadiña, PhD
2013-05-01
Full Text Available Phantom-limb pain (PLP is a phenomenon that may appear among people with amputation. Some studies reveal that 70% of people with amputation experience PLP years postamputation. There is a lack of scientific evidence about the cause of PLP. It has been hypothesized that the autonomic nervous system (ANS could be involved in the mechanism that triggers PLP, but this hypothesis remains unclear. The aim of this study was to correlate ANS function, through heart rate variability (HRV analysis, with PLP in adult males with amputation. The study population comprised 35 subjects, with 27 reporting PLP often or always. The rest of the subjects did not report any PLP. In order to calculate linear and nonlinear parameters of HRV, all subjects underwent 10 min of resting heart rate monitoring. The study did not find correlations between HRV parameters and PLP. Most of the subjects showed decreased values in linear parameters of HRV while nonlinear values were normal. HRV is not implicated in PLP. Linear and nonlinear methods for HRV analysis might reflect different physiological phenomena; while linear values place people with amputation at cardiovascular risk, nonlinear values indicate normality.
Sarabia Cachadiña, Elena; Granados García, Pablo; Tonon Da Luz, S C; Goya Esteban, Rebeca; Barquero Pérez, Oscar; Naranjo Orellana, J; Berral de la Rosa, F J
2013-01-01
Phantom-limb pain (PLP) is a phenomenon that may appear among people with amputation. Some studies reveal that 70% of people with amputation experience PLP years postamputation. There is a lack of scientific evidence about the cause of PLP. It has been hypothesized that the autonomic nervous system (ANS) could be involved in the mechanism that triggers PLP, but this hypothesis remains unclear. The aim of this study was to correlate ANS function, through heart rate variability (HRV) analysis, with PLP in adult males with amputation. The study population comprised 35 subjects, with 27 reporting PLP often or always. The rest of the subjects did not report any PLP. In order to calculate linear and nonlinear parameters of HRV, all subjects underwent 10 min of resting heart rate monitoring. The study did not find correlations between HRV parameters and PLP. Most of the subjects showed decreased values in linear parameters of HRV while nonlinear values were normal. HRV is not implicated in PLP. Linear and nonlinear methods for HRV analysis might reflect different physiological phenomena; while linear values place people with amputation at cardiovascular risk, nonlinear values indicate normality. PMID:23881769
Rotational modulation of the linear polarimetric variability of the cool dwarf TVLM 513$-$46546
Miles-Páez, P A; Pallé, E
2015-01-01
Aims: We aimed to monitor the optical linear polarimetric signal of the magnetized, rapidly rotating M8.5 dwarf TVLM 513$-$46546. Methods: $R$- and $I$-band linear polarimetry images were collected with the ALFOSC instrument of the 2.56-m Nordic Optical Telescope on two consecutive nights covering about 0.5 and 4 rotation cycles in the $R$ and $I$ filters, respectively. We also obtained simultaneous intensity curves by means of differential photometry. The typical precision of the data is $\\pm$0.46\\% ($R$), $\\pm$0.35\\% ($I$) in the linear polarization degree and $\\pm$9 mmag ($R$), $\\pm$1.6 mmag ($I$) in the differential intensity curves. Results: Strong and variable linear polarization is detected in the $R$ and $I$ filters, with values of maximum polarization ($p^{*}$ = 1.30$\\pm$0.35 \\%) similar for both bands. The intensity and the polarimetric curves present a sinusoid-like pattern with a periodicity of $\\sim$1.98 h, which we ascribe to structures in TVLM 513$-$46's surface synchronized with rotation. We f...
Kleshchegonov, S A; Kan'kovska, O I
2009-01-01
Some indices of non-linear heart rate variability (HRV) in pregnant women were assessed with reference to early diagnosis of gestational pathology. It was shown that simultaneous decrease of approximate entropy (ApEn) as low as 1.96 and increase of detrended fluctuation analysis (DFA) parameter of more than 0.85 are associated with the development of severe complications of pregnancy in 75% of the cases examined between 16 and 23 weeks. The informative value of isolated DFA index is twice that of ApEn. Combined use of DFA and ApEn indices of non-linear HRV ensures a 12 times higher probability of correct prognosis of obstetric pathology compared with theoretical (apriori) probability. PMID:19711523
Guo, Ying; Lv, Geli; Zeng, Guihua
2015-11-01
We show that the tolerable excess noise can be dynamically balanced in source preparation while inserting a tunable linear optics cloning machine (LOCM) for balancing the secret key rate and the maximal transmission distance of continuous-variable quantum key distribution (CVQKD). The intensities of source noise are sensitive to the tunable LOCM and can be stabilized to the suitable values to eliminate the impact of channel noise and defeat the potential attacks even in the case of the degenerated linear optics amplifier (LOA). The LOCM-additional noise can be elegantly employed by the reference partner of reconciliation to regulate the secret key rate and the transmission distance. Simulation results show that there is a considerable improvement in the secret key rate of the LOCM-based CVQKD while providing a tunable LOCM for source preparation with the specified parameters in suitable ranges.
Seidou, O.; Asselin, J. J.; Ouarda, T. B. M. J.
2007-08-01
Multivariate linear regression is one of the most popular modeling tools in hydrology and climate sciences for explaining the link between key variables. Piecewise linear regression is not always appropriate since the relationship may experiment sudden changes due to climatic, environmental, or anthropogenic perturbations. To address this issue, a practical and general approach to the Bayesian analysis of the multivariate regression model is presented. The approach allows simultaneous single change point detection in a multivariate sample and can account for missing data in the response variables and/or in the explicative variables. It also improves on recently published change point detection methodologies by allowing a more flexible and thus more realistic prior specification for the existence of a change and the date of change as well as for the regression parameters. The estimation of all unknown parameters is achieved by Monte Carlo Markov chain simulations. It is shown that the developed approach is able to reproduce the results of Rasmussen (2001) as well as those of Perreault et al. (2000a, 2000b). Furthermore, two of the examples provided in the paper show that the proposed methodology can readily be applied to some problems that cannot be addressed by any of the above-mentioned approaches because of limiting model structure and/or restrictive prior assumptions. The first of these examples deals with single change point detection in the multivariate linear relationship between mean basin-scale precipitation at different periods of the year and the summer-autumn flood peaks of the Broadback River located in northern Quebec, Canada. The second one addresses the problem of missing data estimation with uncertainty assessment in multisite streamflow records with a possible simultaneous shift in mean streamflow values that occurred at an unknown date.
Variable selection in multiple linear regression: The influence of individual cases
SJ Steel
2007-12-01
Full Text Available The influence of individual cases in a data set is studied when variable selection is applied in multiple linear regression. Two different influence measures, based on the C_p criterion and Akaike's information criterion, are introduced. The relative change in the selection criterion when an individual case is omitted is proposed as the selection influence of the specific omitted case. Four standard examples from the literature are considered and the selection influence of the cases is calculated. It is argued that the selection procedure may be improved by taking the selection influence of individual data cases into account.
Controlling Continuous-Variable Quantum Key Distribution with Tuned Linear Optics Cloning Machines
Guo, Ying; Qiu, Deli; Huang, Peng; Zeng, Guihua
2015-09-01
We show that the tolerable excess noise can be elegantly controlled while inserting a tunable linear optics cloning machine (LOCM) for continuous-variable key distribution (CVQKD). The LOCM-tuned noise can be stabilized to an optimal value by the reference partner of reconciliation to guarantee the high secret key rate. Simulation results show that there is a considerable improvement of the performance for the LOCM-based CVQKD protocol in terms of the secret rate while making a fine balance between the secret key rate and the transmission distance with the dynamically tuned parameters in suitable ranges.
DISCRETE VARIABLE STRUCTURE CONTROL OF LINEAR TIME-INVARIANT SYSTEMS WITH TIME DELAY
蔡国平; 黄金枝
2002-01-01
A discrete variable structure control(DVSC) method for the linear time-invariant systems with time delay was presented. The continuous time-delay systems are first transformed into the standard discrete form which contains no time delay by augmenting the state variables. Then the switching surface is determined by using the ideal quasi-sliding mode. As it is difficult for the state trajectory to reach the switching surface exactly, the reaching condition in the form of approach law is used to design the controller. The deduced switching surface and controller contain not only the current step of state feedback but also some former steps of controls. Stability analysis with and without time-delay information is also investigated in this paper. Numerical simulation was carried out to demonstrate the effectiveness and feasibility of the presented control method.
Hansen, Niels Chr.; Sadakata, Makiko; Pearce, Marcus
It is a long-held belief in historical musicology that the prosody of composers’ native languages is reflected in the rhythmic and melodic properties of their music. Applying the normalised Pairwise Variability Index (nPVI) to speech alongside musical scores, research has established quantitative...... similarities between durational variability in language and music. This work capitalises on the fact that syllable-timed languages like Italian and French have low nPVI while stress-timed languages like German and Austro-German have high nPVI. Extending this approach to analyses of historical developments, a...... recent paper ascribed linearly increasing nPVI in Austro-German music, but not Italian music, to waning Italian influence on Austro-German music after the Baroque Era. This “Italian Influence Hypothesis” is, however, a post-hoc hypothesis, and since we cannot perform controlled experiments on historical...
We present mid-IR and radio observations of the Galactic luminous blue variables (LBVs) candidate HD 168625 and its associated nebula. We obtained mid-IR spectroscopic observations using the Infrared Spectrograph on board the Spitzer Space Telescope, and performed mid-IR and radio imaging observations using VISIR on the Very Large Telescope and the Very Large Array with comparable angular resolution. Our spectroscopic observations detected spectral features attributable to polycyclic aromatic hydrocarbons (PAHs) and therefore indicate the presence of a photodissociation region (PDR) around the ionized nebula. This result increases the number of LBVs and LBV candidates where a PDR has been found, confirming the importance of such a component in the total mass-loss budget of the central object during this elusive phase of massive star evolution. We have analyzed and compared the mid-IR and radio maps, and derive several results concerning the associated nebula. There is evidence for grain distribution variations across the nebula, with a predominant contribution from bigger grains in the northern part of the nebula while PAH and smaller grains are more concentrated in the southern part. A compact radio component located where there is a lack of thermal dust grains corroborates the presence of a shock in the southern nebula, which could arise as a consequence of the interaction of a fast outflow with the slower, expanding dusty nebula. Such a shock would be a viable means for PAH production as well as for changes in the grain size distribution. Finally, from the detection of a central radio component probably associated with the wind from the central massive supergiant, we derive a current mass-loss rate of M-dot =(1.46±0.15)x10-6 Msun yr-1.
Homogenization of linear viscoelastic heterogeneous media is here extended from two phase inclusion-matrix media to three phase inclusion-matrix media. Each phase obeying to a compressible Maxwellian behaviour, this analytic method leads to an equivalent elastic homogenization problem in the Laplace-Carson space. For some particular microstructures, such as the Hashin composite sphere assemblage, an exact solution is obtained. The inversion of the Laplace-Carson transforms of the overall stress-strain behaviour gives in such cases an internal variable formulation. As expected, the number of these internal variables and their evolution laws are modified to take into account the third phase. Moreover, evolution laws of averaged stresses and strains per phase can still be derived for three phase media. Results of this model are compared to full fields computations of representative volume elements using finite element method, for various concentrations and sizes of inclusion. Relaxation and creep test cases are performed in order to compare predictions of the effective response. The internal variable formulation is shown to yield accurate prediction in both cases. (authors)
Yu. I. Shapovalov
2015-03-01
Full Text Available Introduction. The architecture of MAOPCs functions system and examples of its application for solving the tasks of multivariate analysis of linear periodically time-variable (LPTV circuits based on the frequency symbolic method are considered in this paper. The method is based on approximation of transfer functions of LPTV circuits in the form of trigonometric polynomials of the Fourier. The MAOPCs functions system is implemented in the environment of MATLAB. Architecture and functions of the system MAOPCs. The system consists of 17 functions that are implemented in the environment of MATLAB. Each function has arguments and global variables and carries out over them identified transformation. Functions and global variables form the input data program for research LPTV circuit and should be defined (set at the time of calling the function. Conclusions. The MAOPCs functions system enables to investigate LPTV circuits, setting in program input data the algorithms for their research and to use a strong symbolic apparatus and other standard functions of the package MATLAB in full, without understanding the deep of mathematical apparatus of implemented methods.
FLORIN MARIUS PAVELESCU
2010-01-01
In econometric models, linear regressions with three explanatory variables are widely used. As examples can be cited: Cobb-Douglas production function with three inputs (capital, labour and disembodied technical change), Kmenta function used for approximation of CES production function parameters, error-correction models, etc. In case of multiple linear regressions, estimated parameters values and some statistical tests are influenced by collinearity between explanatory variables. In fact, co...
We present a new quasi-stellar object (QSO) selection algorithm using a Support Vector Machine, a supervised classification method, on a set of extracted time series features including period, amplitude, color, and autocorrelation value. We train a model that separates QSOs from variable stars, non-variable stars, and microlensing events using 58 known QSOs, 1629 variable stars, and 4288 non-variables in the MAssive Compact Halo Object (MACHO) database as a training set. To estimate the efficiency and the accuracy of the model, we perform a cross-validation test using the training set. The test shows that the model correctly identifies ∼80% of known QSOs with a 25% false-positive rate. The majority of the false positives are Be stars. We applied the trained model to the MACHO Large Magellanic Cloud (LMC) data set, which consists of 40 million light curves, and found 1620 QSO candidates. During the selection none of the 33,242 known MACHO variables were misclassified as QSO candidates. In order to estimate the true false-positive rate, we crossmatched the candidates with astronomical catalogs including the Spitzer Surveying the Agents of a Galaxy's Evolution LMC catalog and a few X-ray catalogs. The results further suggest that the majority of the candidates, more than 70%, are QSOs.
Non-linear variability in microquasars in relation with the winds from their accretion disks
Janiuk, Agnieszka; Sukova, Petra; Capitanio, Fiamma; Bianchi, Stefano; Kowalski, Wojtek
2016-01-01
The microquasar IGR J17091, which is the recently discovered analogue of the well known source GRS 1915+105, exhibits quasi-periodic outbursts, with a period of 5-70 seconds, and regular amplitudes, referred to as "heartbeat state". We argue that these states are plausibly explained by accretion disk instability, driven by the dominant radiation pressure. Using our GLobal Accretion DIsk Simulation hydrodynamical code, we model these outbursts quantitatively. We also find a correlation between the presence of massive outflows launched from the accretion disk and the stabilization of its oscillations. We verify the theoretical predictions with the available timing and spectral observations. Furthermore, we postulate that the underlying non-linear differential equations that govern the evolution of an accretion disk are responsible for the variability pattern of several other microquasars, including XTE J1550-564, GX 339-4, and GRO J1655-40. This is based on the signatures of deterministic chaos in the observed ...
Zhang, Henggui; Aziz, Wajid; Monfredi, Oliver; Abbas, Syed Ali; Shah, Saeed Arif; Kazmi, Syeda Sobia Hassan; Butt, Wasi Haider
2016-01-01
The dynamical fluctuations in the rhythms of biological systems provide valuable information about the underlying functioning of these systems. During the past few decades analysis of cardiac function based on the heart rate variability (HRV; variation in R wave to R wave intervals) has attracted great attention, resulting in more than 17000-publications (PubMed list). However, it is still controversial about the underling mechanisms of HRV. In this study, we performed both linear (time domain and frequency domain) and nonlinear analysis of HRV data acquired from humans and animals to identify the relationship between HRV and heart rate (HR). The HRV data consists of the following groups: (a) human normal sinus rhythm (n = 72); (b) human congestive heart failure (n = 44); (c) rabbit sinoatrial node cells (SANC; n = 67); (d) conscious rat (n = 11). In both human and animal data at variant pathological conditions, both linear and nonlinear analysis techniques showed an inverse correlation between HRV and HR, supporting the concept that HRV is dependent on HR, and therefore, HRV cannot be used in an ordinary manner to analyse autonomic nerve activity of a heart. PMID:27336907
Hippotherapy acute impact on heart rate variability non-linear dynamics in neurological disorders.
Cabiddu, Ramona; Borghi-Silva, Audrey; Trimer, Renata; Trimer, Vitor; Ricci, Paula Angélica; Italiano Monteiro, Clara; Camargo Magalhães Maniglia, Marcela; Silva Pereira, Ana Maria; Rodrigues das Chagas, Gustavo; Carvalho, Eliane Maria
2016-05-15
Neurological disorders are associated with autonomic dysfunction. Hippotherapy (HT) is a therapy treatment strategy that utilizes a horse in an interdisciplinary approach for the physical and mental rehabilitation of people with physical, mental and/or psychological disabilities. However, no studies have been carried out which evaluated the effects of HT on the autonomic control in these patients. Therefore, the objective of the present study was to investigate the effects of a single HT session on cardiovascular autonomic control by time domain and non-linear analysis of heart rate variability (HRV). The HRV signal was recorded continuously in twelve children affected by neurological disorders during a HT session, consisting in a 10-minute sitting position rest (P1), a 15-minute preparatory phase sitting on the horse (P2), a 15-minute HT session (P3) and a final 10-minute sitting position recovery (P4). Time domain and non-linear HRV indices, including Sample Entropy (SampEn), Lempel-Ziv Complexity (LZC) and Detrended Fluctuation Analysis (DFA), were calculated for each treatment phase. We observed that SampEn increased during P3 (SampEn=0.56±0.10) with respect to P1 (SampEn=0.40±0.14, pdisabilities attributable to neurological disorders by eliciting an acute autonomic response during the therapy and during the recovery period. PMID:26988283
A light sheet confocal microscope for image cytometry with a variable linear slit detector
Hutcheson, Joshua A.; Khan, Foysal Z.; Powless, Amy J.; Benson, Devin; Hunter, Courtney; Fritsch, Ingrid; Muldoon, Timothy J.
2016-03-01
We present a light sheet confocal microscope (LSCM) capable of high-resolution imaging of cell suspensions in a microfluidic environment. In lieu of conventional pressure-driven flow or mechanical translation of the samples, we have employed a novel method of fluid transport, redox-magnetohydrodynamics (redox-MHD). This method achieves fluid motion by inducing a small current into the suspension in the presence of a magnetic field via electrodes patterned onto a silicon chip. This on-chip transportation requires no moving parts, and is coupled to the remainder of the imaging system. The microscopy system comprises a 450 nm diode 20 mW laser coupled to a single mode fiber and a cylindrical lens that converges the light sheet into the back aperture of a 10x, 0.3 NA objective lens in an epi-illumination configuration. The emission pathway contains a 150 mm tube lens that focuses the light onto the linear sensor at the conjugate image plane. The linear sensor (ELiiXA+ 8k/4k) has three lateral binning modes which enables variable detection aperture widths between 5, 10, or 20 μm, which can be used to vary axial resolution. We have demonstrated redox-MHD-enabled light sheet microscopy in suspension of fluorescent polystyrene beads. This approach has potential as a high-throughput image cytometer with myriad cellular diagnostic applications.
Abramov, Rafail V
2011-01-01
Chaotic multiscale dynamical systems are common in many areas of science, one of the examples being the interaction of the slow climate dynamics with the fast turbulent weather dynamics. One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation property promotes the suppression of chaos at the slow variables through the rapid mixing at the fast variables, both theoretically and through numerical simulations. A suitable mathematical framework is developed, connecting the slow dynamics on the tangent subspaces to the infinite-time linear response of the mean state to a constant external forcing at the fast variables. Additionally, it is shown that the uncoupled dynamics for the slow variables may remain chaotic while the complete multiscale system loses chaos and becomes completely pred...
Relating Linear and Volumetric Variables Through Body Scanning to Improve Human Interfaces in Space
Margerum, Sarah E.; Ferrer, Mike A.; Young, Karen S.; Rajulu, Sudhakar
2010-01-01
Designing space suits and vehicles for the diverse human population present unique challenges for the methods of traditional anthropometry. Space suits are bulky and allow the operator to shift position within the suit and inhibit the ability to identify body landmarks. Limited suit sizing options also cause variability in fit and performance between similarly sized individuals. Space vehicles are restrictive in volume in both the fit and the ability to collect data. NASA's Anthropometric and Biomechanics Facility (ABF) has utilized 3D scanning to shift from traditional linear anthropometry to explore and examine volumetric capabilities to provide anthropometric solutions for design. Overall, the key goals are to improve the human-system performance and develop new processes to aid in the design and evaluation of space systems. Four case studies are presented that illustrate the shift from purely linear analyses to an augmented volumetric toolset to predict and analyze the human within the space suit and vehicle. The first case study involves the calculation of maximal head volume to estimate total free volume in the helmet for proper air exchange. Traditional linear measurements resulted in an inaccurate representation of the head shape, yet limited data exists for the determination of a large head volume. Steps were first taken to identify and classify a maximum head volume and the resulting comparisons to the estimate are presented in this paper. This study illustrates the gap between linear components of anthropometry and the need for overall volume metrics in order to provide solutions. A second case study examines the overlay of the space suit scans and components onto scanned individuals to quantify fit and clearance to aid in sizing the suit to the individual. Restrictions in space suit size availability present unique challenges to optimally fit the individual within a limited sizing range while maintaining performance. Quantification of the clearance and
Potirakis, Stelios M.; Contoyiannis, Yiannis; Melis, Nikolaos S.; Kopanas, John; Antonopoulos, George; Balasis, Georgios; Kontoes, Charalampos; Nomicos, Constantinos; Eftaxias, Konstantinos
2016-08-01
The preparation process of two recent earthquakes (EQs) that occurred in Cephalonia (Kefalonia), Greece, ((38.22° N, 20.53° E), 26 January 2014, Mw = 6.0, depth ˜ 20 km) and ((38.25° N, 20.39° E), 3 February 2014, Mw = 5.9, depth ˜ 10 km), respectively, is studied in terms of the critical dynamics revealed in observables of the involved non-linear processes. Specifically, we show, by means of the method of critical fluctuations (MCF), that signatures of critical, as well as tricritical, dynamics were embedded in the fracture-induced electromagnetic emissions (EMEs) recorded by two stations in locations near the epicentres of these two EQs. It is worth noting that both the MHz EMEs recorded by the telemetric stations on the island of Cephalonia and the neighbouring island of Zante (Zakynthos) reached a simultaneously critical condition a few days before the occurrence of each earthquake. The critical characteristics embedded in the EME signals were further verified using the natural time (NT) method. Moreover, we show, in terms of the NT method, that the foreshock seismic activity also presented critical characteristics before each event. Importantly, the revealed critical process seems to be focused on the area corresponding to the western Cephalonia zone, following the seismotectonic and hazard zoning of the Ionian Islands area near Cephalonia.
Nelson Maculan; Gérard Plateau; Abdel Lisser
2003-01-01
We present integer linear models with a polynomial number of variables and constraints for combinatorial optimization problems in graphs: optimum elementary cycles, optimum elementary paths and optimum tree problems.Apresentamos modelos lineares inteiros com um número polinomial de variáveis e restrições para problemas de otimização combinatória em grafos: ciclos elementares ótimos, caminhos elementares ótimos e problemas em árvores ótimas.
A. Aminataei
2014-05-01
Full Text Available In this paper, a new and ecient approach is applied for numerical approximation of the linear dierential equations with variable coecients based on operational matrices with respect to Hermite polynomials. Explicit formulae which express the Hermite expansioncoecients for the moments of derivatives of any dierentiable function in terms of the original expansion coecients of the function itself are given in the matrix form. The mainimportance of this scheme is that using this approach reduces solving the linear dierentialequations to solve a system of linear algebraic equations, thus greatly simplifying the problem. In addition, two experiments are given to demonstrate the validity and applicability of the method
Rodrigues-da-Silva, Rodrigo Nunes; Martins da Silva, João Hermínio; Singh, Balwan; Jiang, Jianlin; Meyer, Esmeralda V S; Santos, Fátima; Banic, Dalma Maria; Moreno, Alberto; Galinski, Mary R; Oliveira-Ferreira, Joseli; Lima-Junior, Josué da Costa
2016-01-01
Synthetic peptide vaccines provide the advantages of safety, stability and low cost. The success of this approach is highly dependent on efficient epitope identification and synthetic strategies for efficacious delivery. In malaria, the Merozoite Surface Protein-9 of Plasmodium vivax (PvMSP9) has been considered a vaccine candidate based on the evidence that specific antibodies were able to inhibit merozoite invasion and recombinant proteins were highly immunogenic in mice and humans. However the identities of linear B-cell epitopes within PvMSP9 as targets of functional antibodies remain undefined. We used several publicly-available algorithms for in silico analyses and prediction of relevant B cell epitopes within PMSP9. We show that the tandem repeat sequence EAAPENAEPVHENA (PvMSP9E795-A808) present at the C-terminal region is a promising target for antibodies, given its high combined score to be a linear epitope and located in a putative intrinsically unstructured region of the native protein. To confirm the predictive value of the computational approach, plasma samples from 545 naturally exposed individuals were screened for IgG reactivity against the recombinant PvMSP9-RIRII729-972 and a synthetic peptide representing the predicted B cell epitope PvMSP9E795-A808. 316 individuals (58%) were responders to the full repetitive region PvMSP9-RIRII, of which 177 (56%) also presented total IgG reactivity against the synthetic peptide, confirming it validity as a B cell epitope. The reactivity indexes of anti-PvMSP9-RIRII and anti-PvMSP9E795-A808 antibodies were correlated. Interestingly, a potential role in the acquisition of protective immunity was associated with the linear epitope, since the IgG1 subclass against PvMSP9E795-A808 was the prevalent subclass and this directly correlated with time elapsed since the last malaria episode; however this was not observed in the antibody responses against the full PvMSP9-RIRII. In conclusion, our findings identified and
Turnbull, Laura; Bracken, Louise; Wainwright, John
2014-05-01
A major challenge for geomorphologists is to scale up small-magnitude erosional processes to predict landscape form and landscape-scale sediment flux. Here, we present a sediment connectivity framework, showing the controls and dynamics of sediment transport which govern erosional processes across multiple scales. This framework is based on the concept that the interplay of structural components (morphology) and process components (flow of energy/transport vectors and materials) determines the long-term behaviour of the sediment flux, which is manifest as a change in landform. The sediment connectivity framework therefore incorporates all aspects of the geomorphic system that control sediment flux. Because of the link between process (flux) and form, sediment connectivity is a product of sediment entrainment and sediment-transport distance and the emergent characteristics of sediment deposition and sediment residence times. Therefore, depending on the dominant processes in operation and their spatial and temporal configuration, the scaling of erosion differs in form and extent. Sediment-transport distances are an integral component of this sediment connectivity framework, as they provide a means of addressing the non-linearity of erosional processes within spatially and temporally variable environments. We apply this sediment-connectivity framework to test how structural and process components of a system alter sediment flux. Specifically, we use a modelling-based approach to investigate how antecedent soil-moisture content and rainfall characteristics affect hydrological and sediment connectivity over a shrub-encroachment gradient in the southwest USA; a region that is undergoing rapid vegetation transitions. We carried out scenario-based runoff and erosion modelling using MAHLERAN to investigate the impact of changes in runoff and erosion to soil moisture and rainfall characteristics. Using outputs from these simulations, we quantify hydrological and sediment
Goulart, Cássia Da Luz; Simon, Julio Cristiano; Schneiders, Paloma De Borba; San Martin, Elisabete Antunes; Cabiddu, Ramona; Borghi-Silva, Audrey; Trimer, Renata; da Silva, Andréa Lúcia Gonçalves
2016-01-01
Introduction Chronic obstructive pulmonary disease (COPD) is recognized as a multisystemic inflammatory disease associated with extrapulmonary comorbidities, including respiratory muscle weakness and cardiovascular and cardiac autonomic regulation disorders. We investigated whether alterations in respiratory muscle strength (RMS) would affect cardiac autonomic modulation in COPD patients. Methods This study was a cross-sectional study done in ten COPD patients affected by moderate to very severe disease. The heart rate variability (HRV) signal was recorded using a Polar cardiofrequencimeter at rest in the sitting position (10 minutes) and during a respiratory sinus arrhythmia maneuver (RSA-M; 4 minutes). Linear analysis in the time and frequency domains and nonlinear analysis were performed on the recorded signals. RMS was assessed using a digital manometer, which provided the maximum inspiratory pressure (PImax) and the maximum expiratory pressure (PEmax). Results During the RSA-M, patients presented an HRV power increase in the low-frequency band (LFnu) (46.9±23.7 vs 75.8±27.2; P=0.01) and a decrease in the high-frequency band (HFnu) (52.8±23.5 vs 24.0±27.0; P=0.01) when compared to the resting condition. Significant associations were found between RMS and HRV spectral indices: PImax and LFnu (r=−0.74; P=0.01); PImax and HFnu (r=0.74; P=0.01); PEmax and LFnu (r=−0.66; P=0.01); PEmax and HFnu (r=0.66; P=0.03); between PEmax and sample entropy (r=0.83; PRSA-M. Conclusion COPD patients with impaired RMS presented altered cardiac autonomic control, characterized by marked sympathetic modulation and a reduced parasympathetic response; reduced HRV complexity was observed during the RSA-M. PMID:27555757
Remy, Pascal
2015-01-01
We investigate Gevrey order and summability properties of formal power series solutions of some classes of inhomogeneous linear partial differential equations with variable coefficients and analytic initial conditions. In particular, we give necessary and sufficient conditions under which these solutions are convergent or are k-summable, for a convenient k, in a given direction.
Kayaalp, G.Tamer
1999-01-01
In animal breeding, when there is a relationship between the dependent (Y) and independent (X) variables, regression analysis is applied. But when one of the variables has one or more missing observations regression analysis cannot be applied. This paper illustrates and discusses a regression analysis in which the independent variable (X) has a missing observation.
Christiansen, Bo
2015-04-01
Linear regression methods are without doubt the most used approaches to describe and predict data in the physical sciences. They are often good first order approximations and they are in general easier to apply and interpret than more advanced methods. However, even the properties of univariate regression can lead to debate over the appropriateness of various models as witnessed by the recent discussion about climate reconstruction methods. Before linear regression is applied important choices have to be made regarding the origins of the noise terms and regarding which of the two variables under consideration that should be treated as the independent variable. These decisions are often not easy to make but they may have a considerable impact on the results. We seek to give a unified probabilistic - Bayesian with flat priors - treatment of univariate linear regression and prediction by taking, as starting point, the general errors-in-variables model (Christiansen, J. Clim., 27, 2014-2031, 2014). Other versions of linear regression can be obtained as limits of this model. We derive the likelihood of the model parameters and predictands of the general errors-in-variables model by marginalizing over the nuisance parameters. The resulting likelihood is relatively simple and easy to analyze and calculate. The well known unidentifiability of the errors-in-variables model is manifested as the absence of a well-defined maximum in the likelihood. However, this does not mean that probabilistic inference can not be made; the marginal likelihoods of model parameters and the predictands have, in general, well-defined maxima. We also include a probabilistic version of classical calibration and show how it is related to the errors-in-variables model. The results are illustrated by an example from the coupling between the lower stratosphere and the troposphere in the Northern Hemisphere winter.
FLORIN MARIUS PAVELESCU
2010-12-01
Full Text Available In econometric models, linear regressions with three explanatory variables are widely used. As examples can be cited: Cobb-Douglas production function with three inputs (capital, labour and disembodied technical change, Kmenta function used for approximation of CES production function parameters, error-correction models, etc. In case of multiple linear regressions, estimated parameters values and some statistical tests are influenced by collinearity between explanatory variables. In fact, collinearity acts as a noise which distorts the signal (proper parameter values. This influence is emphasized by the coefficients of alignment to collinearity hazard values. The respective coefficients have some similarities with the signal to noise ratio. Consequently, it may be used when the type of collinearity is determined. For these reasons, the main purpose of this paper is to identify all the modeling factors and quantify their impact on the above-mentioned indicator values in the context of linear regression with three explanatory variables.Classification-JEL:C13,C20,C51,C52Keywords:types of collinearity, coefficient of mediated correlation, rank of explanatory variable, order of attractor of collinearity, mediated collinearity, anticollinearity.
Zheng-yan Lin; Yu-ze Yuan
2012-01-01
Semiparametric models with diverging number of predictors arise in many contemporary scientific areas. Variable selection for these models consists of two components: model selection for non-parametric components and selection of significant variables for the parametric portion.In this paper,we consider a variable selection procedure by combining basis function approximation with SCAD penalty.The proposed procedure simultaneously selects significant variables in the parametric components and the nonparametric components.With appropriate selection of tuning parameters,we establish the consistency and sparseness of this procedure.
Nelson Maculan
2003-01-01
Full Text Available We present integer linear models with a polynomial number of variables and constraints for combinatorial optimization problems in graphs: optimum elementary cycles, optimum elementary paths and optimum tree problems.Apresentamos modelos lineares inteiros com um número polinomial de variáveis e restrições para problemas de otimização combinatória em grafos: ciclos elementares ótimos, caminhos elementares ótimos e problemas em árvores ótimas.
Kim Gaik Tay
2010-04-01
Full Text Available In the present work, by considering the artery as a prestressed thin-walled elastic tube with a symmetrical stenosis and the blood as an incompressible viscous fluid, we have studied the amplitude modulation of nonlinear waves in such a composite medium through the use of the reductive perturbation method [23]. The governing evolutions can be reduced to the dissipative non-linear Schrodinger (NLS equation with variable coefficient. The progressive wave solution to the above non-linear evolution equation is then sought.
陈化; 罗壮初
2002-01-01
In this paper the authors study a class of non-linear singular partial differential equation in complex domain Ct × Cnx. Under certain assumptions, they prove the existence and uniqueness of holomorphic solution near origin of Ct × Cnx.
Analysis of Design Variables of Annular Linear Induction Electromagnetic Pump using an MHD Model
The generated force is affected by lots of factors including electrical input, hydrodynamic flow, geometrical shape, and so on. These factors, which are the design variables of an ALIP, should be suitably analyzed to optimally design an ALIP. Analysis on the developed pressure and efficiency of the ALIP according to the change of design variables is required for the ALIP satisfying requirements. In this study, the design variables of the ALIP are analyzed by using ideal MHD analysis model. Electromagnetic force and efficiency are derived by analyzing the main design variables such as pump core length, inner core diameter, flow gap and turns of coils. The developed pressure and efficiency of the ALIP were derived and analyzed on the change of the main variables such as pump core length, inner core diameter, flow gap, and turns of coils of the ALIP
Analysis of Design Variables of Annular Linear Induction Electromagnetic Pump using an MHD Model
Kwak, Jae Sik; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2015-05-15
The generated force is affected by lots of factors including electrical input, hydrodynamic flow, geometrical shape, and so on. These factors, which are the design variables of an ALIP, should be suitably analyzed to optimally design an ALIP. Analysis on the developed pressure and efficiency of the ALIP according to the change of design variables is required for the ALIP satisfying requirements. In this study, the design variables of the ALIP are analyzed by using ideal MHD analysis model. Electromagnetic force and efficiency are derived by analyzing the main design variables such as pump core length, inner core diameter, flow gap and turns of coils. The developed pressure and efficiency of the ALIP were derived and analyzed on the change of the main variables such as pump core length, inner core diameter, flow gap, and turns of coils of the ALIP.
MENKA PETKOVSKA
2000-12-01
Full Text Available The concept of higher order frequency response functions (FRFs is used for the analysis of non-linear adsorption kinetics on a particle scale, for the case of non-isothermal micropore diffusion with variable diffusivity. Six series of FRFs are defined for the general non-isothermal case. A non-linerar mathematical model is postulated and the first and second order FRFs derived and simulated. A variable diffusivity influences the shapes of the second order FRFs relating the sorbate concentration in the solid phase and t he gas pressure significantly, but they still keep their characteristics which can be used for discrimination of this from other kinetic mechanisms. It is also shown that first and second order particle FRFs offter sufficient information for an easy and fast estimation of all model parameters, including those defining the system non-linearity.
Emadi, A.; Wu, H; De Graaf, G.; Wolffenbuttel, R.F.
2011-01-01
In this paper the concept of a microspectrometer based on a Linear Variable Optical Filter (LVOF) for operation in the visible spectrum is presented and used in two different designs: the first is for the narrow spectral band between 610 nm and 680 nm, whereas the other is for the wider spectral band between 570 nm and 740 nm. Design considerations, fabrication and measurement results of the LVOF are presented. An iterative signal processing algorithm based on an initial calibration has been ...
Ünal
2015-08-01
Full Text Available The goal of this study is to study the candidate students of university lecturer’s the skills of solving problem acording to the difrent variables. İn the study , the descriptive survey model has been used. the stduy of 2013-2014 education-teaching academic year involves one thousand students of candidate teacher from the deparment of classroom teaching and the department of physical education and sports from different universities such as the university of Ahi Evran the university of Gazi Osman Paşa, the university of Kahramanmaraş Sütçü İmam and the university of Gaziantep. The form of personal in formation prepared by the resarcher and the inventory of solving problem developed by Heppner Peterson ( 1982 have been used as the datas of the study. The scale has been translated by Şahin and Heppner (1993. The inferential Analyses have been done on the collected datas such as t-test, LSD,and ANOVA (p<0.05. Acording to the results, there is no difference between the variable of class and age of the attendants on the other hand , there is a meaning ful difference between the variable of educating programme, sex, living place, the education of mother and father, the profession of mother and father and the level of family income .
Effect of milk proteins on linear growth and IGF variables in overweight adolescents
Larnkjær, Anni; Arnberg, Karina; Michaelsen, Kim F;
2014-01-01
Milk may stimulate growth acting via insulin-like growth factor-I (IGF-I) secretion but the effect in adolescents is less examined. This study investigates the effect of milk proteins on linear growth, IGF-I, IGF binding protein-3 (IGFBP-3) and IGF-I/IGFBP-3 ratio in overweight adolescents....
Chen, Hua; Lua, Zhuangehu
2008-01-01
In this paper we study a class of non-linear singular partial differential equation in complex domain Csub(t) x C n sub(x). Under certain assumptions, we prove the existence and uniqueness of holomorphic solution near origin of Csub(t) x C n sub(x).
A New Linear Oscillatory Actuator with Variable Characteristics Using Two Sets of Coils.
Kitayama, Fumiya; Hirata, Katsuhiro; Niguchi, Noboru; Kobayashi, Masashi
2016-01-01
Nowadays, electromagnetic linear oscillatory actuators are used as vibration control devices because of their high controllability. However, there is a problem that thrust and vibration are small at a wide drive frequency range. In order to improve this problem, we propose a new linear oscillatory actuator that can easily change its own characteristics by using two sets of coils. Through finite element analysis, large vibration was observed at 100 Hz in a series connection, and large vibration and high thrust were observed at 70 Hz and 140 Hz in a parallel connection. From these results, we verified that the actuator had two different characteristics due to switchable connections, and could generate high thrust and large vibration by smaller currents at a wide drive frequency range. PMID:26999136
R. E. Chandler; Wheater, H. S.
2002-01-01
In the early 1990s a cluster of extreme flood events occurred in the south Galway region of western Ireland, and this led to speculation of changing rainfall patterns in the area. In this paper we illustrate the use of generalized linear models (GLMs) to test for such changes and quantify their structure. GLMs, long established in the statistical literature, provide a flexible and rigorous formal framework within which to distinguish between possible climate change scenarios and are able to d...
Rindskopf, David
1984-01-01
Using LISREL, the only types of constraints allowed are fixing parameters at a constant value and constraining parameters to be equal. In this paper, two new concepts ("phantom" and "imaginary" latent variables) are introduced which allow fairly general equality and inequality constraints on factor loadings and structural model coefficients.…
We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole accreting material from a close companion. We created long-term light curves for these sources, correcting for background, interstellar absorption, and instrumental effects. We tested for variability by examining the goodness of fit for the best-fit constant intensity. We also created structure functions (SFs) for every object in our sample, the first time this technique has been applied to XBs. We found significant variability in 28 out of 34 GCs and GC candidates; the other 6 sources had 0.3-10 keV luminosities fainter than ∼2 × 1036 erg s–1, limiting our ability to detect similar variability. The SFs of XBs with 0.3-10 keV luminosities ∼2-50 × 1036 erg s–1 generally showed considerably more variability than the published ensemble SF of active galactic nuclei (AGNs). Our brightest XBs were mostly consistent with the AGN SF; however, their 2-10 keV fluxes could be matched by <1 AGN per square degree. These encouraging results suggest that examining the long-term light curves of other X-ray sources in the field may provide an important distinction between X-ray binaries and background galaxies, as the X-ray emission spectra from these two classes of X-ray sources are similar. Additionally, we identify 3 new black hole candidates (BHCs) using additional XMM-Newton data, bringing the total number of M31 GC BHCs to 9, with 8 covered in this survey.
Ahangar, Reza Gharoie; Pournaghshband, Hassan
2010-01-01
In this paper, researchers estimated the stock price of activated companies in Tehran (Iran) stock exchange. It is used Linear Regression and Artificial Neural Network methods and compared these two methods. In Artificial Neural Network, of General Regression Neural Network method (GRNN) for architecture is used. In this paper, first, researchers considered 10 macro economic variables and 30 financial variables and then they obtained seven final variables including 3 macro economic variables and 4 financial variables to estimate the stock price using Independent components Analysis (ICA). So, we presented an equation for two methods and compared their results which shown that artificial neural network method is more efficient than linear regression method.
Non-Linear Dynamics of Macroeconomic Variables: The Case of Greece
Sophia Kassapi
2015-06-01
Full Text Available This paper is part of an ongoing doctoral dissertation. It examines the long run relationship between government spending on education, GDP growth and educational enrollments in all levels, for Greece in the years 1960-2012, leveling up to capture more complex dependent dynamics in time series. OECD Indicator A11 shows that, life satisfaction, civic engagement and health. are at the same level for adults with tertiary education and adults with upper secondary education for Greece. Having conducted Linear Granger tests, this study goes beyond, following the methodology of both non-parametric testing for asymptotic Granger causality in C, and non-parametric bootstrapped bidirectional Granger causality, an MS Dos application in C. We apply a new nonparametric test for Granger non-causality by Diks and Panchenko (2005, 2006 as well as the conventional linear Granger test on the time series. The secondary data used in this present study, have been processed through MATLAB interpolation function. There is a strong symmetric nonlinear causal relationship detected between government spending on education and enrollments in higher education, and vice versa, .An even stronger, both symmetric and asymmetric nonlinear relationship between higher education enrollments and Gdp growth is validated confirming a spectacular case of “adverse causality”. Government spending in education is causally related with Gdp growth in a symmetric as much as an asymmetric nonlinear relationship. Also, lagged values of secondary enrollments are a major predictor of Gdp growth. Keywords: Economic growth, Greek economy, Granger Causality, Non-linearity.
M. G. Poddar; Vinod Kumar; Yash Paul Sharma
2014-01-01
The aim of this study is to analyse and compare the heart rate variability (HRV) of normal and hypertension cases using time domain, frequency domain, and nonlinear methods. For short term HRV analysis, a five-minute electrocardiogram (ECG) of 57 normal and 56 hypertension subjects were recorded with prior verification of their clinical status by a cardiologist. Most time domain features of hypertension cases have clearly reduced values over normal subjects, frequency domain features, like po...
On the Godunov Scheme Applied to the Variable Cross-Section Linear Wave Equation
We investigate the accuracy of the Godunov scheme applied to the variable cross-section acoustic equations. Contrarily to the constant cross-section case, the accuracy issue of this scheme in the low Mach number regime appears even in the one-dimensional case; on the other hand, we show that it is possible to construct another Godunov type scheme which is accurate in the low Mach number regime. (authors)
THE BLUE AND MINQUE IN GAUSS-MARKOFF MODEL WITH LINEAR TRANSFORMATION OF THE OBSERVABLE VARIABLES
无
2007-01-01
For a singular linear model A = (y, Xβ, σ2 V) and its transformed model AF = (Fy, FXβ, σ2FVF'), where V is nonnegative definite and X can be rank-deficient,the expressions for the differences of the estimates for the vector of FXβ and the variance factor σ2 are given. Moreover, the necessary and sufficient conditions for the equalities of the estimates for the vector of FXβ and the variance factor σ2 are also established. In the meantime, works in Baksalary and Kala (1981) are strengthened and consequences in Puntanen and Nurhonen (1992), and Puntanen (1996) are extended.
Linear-Number-of-Variables Kernel for Unit-Conflict-Free-Max-Sat Parameterized Above Expectation
Crowston, R; Jones, M; Yeo, A
2010-01-01
A formula $F$ in conjunctive normal form (CNF) is unit-conflict free (UCF) if for no variable $x$ both clauses, $(x)$ and $(\\bar{x})$ appear in $F$. It is well-known that for a UCF CNF with $n$ variables and $m$ clauses, it is always possible to satisfy at least $p\\cdot m$ clauses, where $p=(\\sqrt{5}-1)/2$. The parameterized problem UCF-Max-Sat-AE asks whether for a given UCF CNF formula it is possible to satisfy at least $p\\cdot m + k$ clauses, where integer $k$ is the parameter. Mahajan and Raman (J. Algorithms 31(2):335--354, 1999) asked whether UCF-Max-Sat-AE is fixed-parameter tractable, i.e., whether UCF-Max-Sat-AE can be solved in time $f(k)(nm)^{O(1)}$ for some computable function $f$ of $k$ only. We prove that UCF-Max-Sat-AE is fixed-parameter tractable by describing a polynomial-time algorithm that transforms any instance of UCF-Max-Sat-AE into an equivalent instance with at most $\\lfloor 4k/(7-3\\sqrt{5})\\rfloor$ variables.
A multi-body aeroelastic design code based on the implementation of the combined aeroelastic beam element is extended to cover closed loop operation conditions of wind turbines. The equations of a controller for variable generator speed and pitch controlled operation in high wind speeds are combined with the aeroelastic equations of motion for the complete wind turbine, in order to provide a compound servo-aeroelastic system of equations. The control equations comprise linear differential equations for the pitch and generator torque actuators, the control feedback elements (PI control) and the various filters acting on the feedback signals. In its non-linear form the dynamic equations are integrated in time to provide the reference state, while upon linearization of the system and transformation in the non-rotating frame, the linear stability equations are derived. Stability results for a multi-MW wind turbine, show that the coupling of the controller dynamics with the aeroelastic dynamics of the machine is important and must be taken into account in view of defining the controller parameters
Kelly, Anne; Jacobsson, Susanne; Hussain, Shahida; Olcén, Per; Mölling, Paula
2013-01-01
The factor H binding protein (fHbp) is currently being evaluated in clinical trials as a vaccine candidate for a meningococcal group B vaccine. We have previously described the prevalence and sequence variation of fHbp (Jacobsson et al., 2009) and here we investigate the expression of the antigen. The present study includes isolates from carriers (n = 62) and patients with invasive Neisseria meningitidis infections (n = 146), of which 62 had a fatal outcome. Among the invasive isolates from patients with fatal and non-fatal infections fHbp allele 1 was most common (42% and 29% respectively), but it was only identified in 3% of the carrier isolates, where allele 16 was most frequent (13%). The Fluorescence-activated cell sorting analysis identified fHbp expression in all except seven isolates and further analysis by Western blot showed that five of these seven samples were indeed negative using a polyclonal anti-fHbp serum. The negative isolates belonged to serogroup B fHbp allele 24, Y allele 104, and W-135 allele 16 (all invasive). Two were non-serogroupable carrier isolates (allele 21 and 101). An interesting finding is that isolates from invasive infections with fatal outcome had lower expression of fHbp or lower affinity for the fHbp antibody compared to isolates from non-fatal invasive infections and carriers. PMID:23030708
无
2005-01-01
The multi-linear variable separation approach (MLVSA ) is very useful to solve (2+ 1)-dimensional integrable systems. In this letter, we extend this method to solve a (1+1)-dimensional coupled integrable dispersion-less system.Namely, by using a Backlund transformation and the MLVSA, we find a new general solution and define a new "universal formula". Then, some new (1+1)-dimensional coherent structures of this universal formula can be found by selecting corresponding functions appropriately. Specially, in some conditions, bell soliton and kink soliton can transform each other, which are illustrated graphically.
Quantization of spin-two field in terms of Fierz variables the linear case
We give a complete self-contained presentation of the description of spin-two fields using Fierz variables A sub(α β μ) instead of the conventional standard approach which deals with second order symmetric tensor φ sub(μ ν). After a short review of the classical properties of the Gierz field we present the quantization procedure. The theory presents a striking similitude with electrodynamics which induced us to follow analogy with the Fermi-Gupta-Breuler scheme of quantization. (author)
Records and sequences of records from random variables with a linear trend
Franke, Jasper; Wergen, Gregor; Krug, Joachim
2010-01-01
We consider records and sequences of records drawn from discrete time series of the form $X_{n}=Y_{n}+cn$, where the $Y_{n}$ are independent and identically distributed random variables and $c$ is a constant drift. For very small and very large drift velocities, we investigate the asymptotic behavior of the probability $p_n(c)$ of a record occurring in the $n$th step and the probability $P_N(c)$ that all $N$ entries are records, i.e. that $X_1 < X_2 < ... < X_N$. Our work is motivated by the ...
Best, William M. J.; Liu, Michael C.; Magnier, Eugene A.; Aller, Kimberly M.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Deacon, Niall R. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Dupuy, Trent J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Redstone, Joshua [Facebook, 335 Madison Ave, New York, NY 10017-4677 (United States); Price, P. A., E-mail: wbest@ifa.hawaii.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
2013-11-10
We present initial results from a wide-field (30,000 deg{sup 2}) search for L/T transition brown dwarfs within 25 pc using the Pan-STARRS1 and Wide-field Infrared Survey Explorer (WISE) surveys. Previous large-area searches have been incomplete for L/T transition dwarfs, because these objects are faint in optical bands and have near-infrared (near-IR) colors that are difficult to distinguish from background stars. To overcome these obstacles, we have cross-matched the Pan-STARRS1 (optical) and WISE (mid-IR) catalogs to produce a unique multi-wavelength database for finding ultracool dwarfs. As part of our initial discoveries, we have identified seven brown dwarfs in the L/T transition within 9-15 pc of the Sun. The L9.5 dwarf PSO J140.2308+45.6487 and the T1.5 dwarf PSO J307.6784+07.8263 (both independently discovered by Mace et al.) show possible spectroscopic variability at the Y and J bands. Two more objects in our sample show evidence of photometric J-band variability, and two others are candidate unresolved binaries based on their spectra. We expect our full search to yield a well-defined, volume-limited sample of L/T transition dwarfs that will include many new targets for study of this complex regime. PSO J307.6784+07.8263 in particular may be an excellent candidate for in-depth study of variability, given its brightness (J = 14.2 mag) and proximity (11 pc)
We present initial results from a wide-field (30,000 deg2) search for L/T transition brown dwarfs within 25 pc using the Pan-STARRS1 and Wide-field Infrared Survey Explorer (WISE) surveys. Previous large-area searches have been incomplete for L/T transition dwarfs, because these objects are faint in optical bands and have near-infrared (near-IR) colors that are difficult to distinguish from background stars. To overcome these obstacles, we have cross-matched the Pan-STARRS1 (optical) and WISE (mid-IR) catalogs to produce a unique multi-wavelength database for finding ultracool dwarfs. As part of our initial discoveries, we have identified seven brown dwarfs in the L/T transition within 9-15 pc of the Sun. The L9.5 dwarf PSO J140.2308+45.6487 and the T1.5 dwarf PSO J307.6784+07.8263 (both independently discovered by Mace et al.) show possible spectroscopic variability at the Y and J bands. Two more objects in our sample show evidence of photometric J-band variability, and two others are candidate unresolved binaries based on their spectra. We expect our full search to yield a well-defined, volume-limited sample of L/T transition dwarfs that will include many new targets for study of this complex regime. PSO J307.6784+07.8263 in particular may be an excellent candidate for in-depth study of variability, given its brightness (J = 14.2 mag) and proximity (11 pc)
A New Cataclysmic Variable RX J0757.0+6306 Candidate for the Shortest Period Intermediate Polar
Tovmassian, G H; Kroll, P; Szkody, P; Mason, P A; Zickgraf, F J; Krautter, J; Thiering, I; Serrano, A; Howell, S; Ciardi, D R
1998-01-01
A new cataclysmic variable is identified as the optical counterpart of the faint and hard X-ray source RX J0757.0+6306 discovered during the ROSAT all-sky survey. Strong double-peaked emission lines bear evidence of an accretion disc via an S-wave which varies with a period of 81 +/- 5 min. We identify this period as the orbital period of the binary system. CCD photometry reveals an additional period of 8.52 +/- 0.15 min. which was stable over four nights. We suggest that RX J0757.0+6306 is possibly an intermediate polar, but we cannot exclude the possibility that it is a member of the SU UMa group of dwarf novae.
A 7MeV S-Band 2998MHz Variable Pulse Length Linear Accelerator System
Hernandez, Michael; Mishin, Andrey V; Saverskiy, Aleksandr J; Skowbo, Dave; Smith, Richard
2005-01-01
American Science and Engineering High Energy Systems Division (AS&E HESD) has designed and commissioned a variable pulse length 7 MeV electron accelerator system. The system is capable of delivering a 7 MeV electron beam with a pulse length of 10 nS FWHM and a peak current of 1 ampere. The system can also produce electron pulses with lengths of 20, 50, 100, 200, 400 nS and 3 uS FWHM with corresponding lower peak currents. The accelerator system consists of a gridded electron gun, focusing coil, an electrostatic deflector system, Helmholtz coils, a standing wave side coupled S-band linac, a 2.6 MW peak power magnetron, an RF circulator, a fast toroid, vacuum system and a PLC/PC control system. The system has been operated at repetition rates up to 250pps. The design, simulations and experimental results from the accelerator system are presented in this paper.
Effects of breathing patterns and light exercise on linear and nonlinear heart rate variability.
Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Kumar, Mohit; Behrens, Martin
2015-08-01
Despite their use in cardiac risk stratification, the physiological meaning of nonlinear heart rate variability (HRV) measures is not well understood. The aim of this study was to elucidate effects of breathing frequency, tidal volume, and light exercise on nonlinear HRV and to determine associations with traditional HRV indices. R-R intervals, blood pressure, minute ventilation, breathing frequency, and respiratory gas concentrations were measured in 24 healthy male volunteers during 7 conditions: voluntary breathing at rest, and metronome guided breathing (0.1, 0.2 and 0.4 Hz) during rest, and cycling, respectively. The effect of physical load was significant for heart rate (HR; p p p p < 0.05 to <0.01). In conclusion, while light exercise does not significantly affect short-time HRV nonlinear indices, respiratory activity has to be considered as a potential contributor at rest and during light dynamic exercise. PMID:26187271
Origins of Total-Dose Response Variability in Linear Bipolar Microcircuits
LM1ll voltage comparators exhibit a wide range of total-dose-induced degradation. Simulations show this variability may be a natural consequence of the low base doping of the substrate PNP (SPNP) input transistors. Low base doping increases the SPNP's collector to base breakdown voltage, current gain, and sensitivity to small fluctuations in the radiation-induced oxide defect densities. The build-up of oxide trapped charge (Not) and interface traps (Nit) is shown to be a function of pre-irradiation bakes. Experimental data indicate that, despite its structural similarities to the LM111, irradiated input transistors of the LM124 operational amplifier do not exhibit the same sensitivity to variations in pre-irradiation thermal cycles. Further disparities in LM111 and LM124 responses may result from a difference in the oxide defect build-up in the two part types. Variations in processing, packaging, and circuit effects are suggested as potential explanations
Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T
2016-01-01
A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070
Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.
2016-01-01
A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070
M. G. Poddar
2014-11-01
Full Text Available The aim of this study is to analyse and compare the heart rate variability (HRV of normal and hypertension cases using time domain, frequency domain, and nonlinear methods. For short term HRV analysis, a five-minute electrocardiogram (ECG of 57 normal and 56 hypertension subjects were recorded with prior verification of their clinical status by a cardiologist. Most time domain features of hypertension cases have clearly reduced values over normal subjects, frequency domain features, like power in different spectral bands, also have the distinguishable decreased values, whereas sympathovagal balance has clear edge over hypertension cases than normal cases. Nonlinear parameters of Poincare plot, approximate entropy and sample entropy, have higher values in normal cases when compared with hypertension cases. Support vector machine-based binary system classifies these two classes with 100 per cent accuracy and 100 per cent sensitivity when all time domain, frequency domain, and nonlinear features were used. It may work as a better predictor for in patients with hypertension.Science Journal, Vol. 64, No. 6, November 2014, pp.542-548, DOI:http://dx.doi.org/10.14429/dsj.64.7867
Humphreys, Roberta M; Davidson, Kris; Bomans, D J; Burggraf, Birgitta
2014-01-01
An increasing number of non-terminal eruptions are being found in the numerous surveys for optical transients. Very little is known about these giant eruptions, their progenitors and their evolutionary state. A greatly improved census of the likely progenitor class, including the most luminous evolved stars, the Luminous Blue Varaibles (LBVs), and the warm and cool hypergiants is now needed for a complete picture of the final pre-SN stages of very massive stars. We have begun a survey of the evolved and un stable luminous star populations in several nearby resolved galaxies. In this second paper on M31 and M33, we review the spectral characteristics, spectral energy distributions, circumstellar ejecta, and evidence for mass loss for 82 luminous and variable stars.We show that many of these stars have warm circumstellar dust including several of the Fe II emission line stars, but conclude that the confirmed LBVs in M31 and M33 do not. The confirmed LBVs have relatively low wind speeds even in their hot, quiesc...
Lee, C. Y.; Tippett, M. K.; Sobel, A. H.; Camargo, S. J.
2014-12-01
We are working towards the development of a new statistical-dynamical downscaling system to study the influence of climate on tropical cyclones (TCs). The first step is development of an appropriate model for TC intensity as a function of environmental variables. We approach this issue with a stochastic model consisting of a multiple linear regression model (MLR) for 12-hour intensity forecasts as a deterministic component, and a random error generator as a stochastic component. Similar to the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS), MLR relates the surrounding environment to storm intensity, but with only essential predictors calculated from monthly-mean NCEP reanalysis fields (potential intensity, shear, etc.) and from persistence. The deterministic MLR is developed with data from 1981-1999 and tested with data from 2000-2012 for the Atlantic, Eastern North Pacific, Western North Pacific, Indian Ocean, and Southern Hemisphere basins. While the global MLR's skill is comparable to that of the operational statistical models (e.g., SHIPS), the distribution of the predicted maximum intensity from deterministic results has a systematic low bias compared to observations; the deterministic MLR creates almost no storms with intensities greater than 100 kt. The deterministic MLR can be significantly improved by adding the stochastic component, based on the distribution of random forecasting errors from the deterministic model compared to the training data. This stochastic component may be thought of as representing the component of TC intensification that is not linearly related to the environmental variables. We find that in order for the stochastic model to accurately capture the observed distribution of maximum storm intensities, the stochastic component must be auto-correlated across 12-hour time steps. This presentation also includes a detailed discussion of the distributions of other TC-intensity related quantities, as well as the inter
Marscher, Alan P
2014-01-01
A single measurement of linear polarization of a nonthermal source provides direct information about the mean direction and level of ordering of the magnetic field. Monitoring of the polarization in blazars, combined with millimeter-wave VLBI imaging in both total and polarized intensity, has the potential to determine the geometry of the magnetic field. This is a key probe of the physical processes in the relativistic jet, such as ordered field components, turbulence, magnetic reconnections, magnetic collimation and acceleration of the jet flow, particle acceleration, and radiative processes that produce extremely luminous, highly variable nonthermal emission. Well-sampled monitoring observations of multi-waveband flux and radio-optical polarization of blazars show a variety of behavior. In some cases, the observed polarization patterns appear systematic, while in others randomness dominates. Explanations involve helical magnetic fields, turbulence, and perhaps particle acceleration that depends on the angle...
Kazemi, A.; Motlagh, M.R. Jahed; Naghshbandy, A.H. [Centre of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran)
2007-05-15
This article investigates the application of a multi-variable nonlinear controller to the model of a power system. The proposed controller is based on the feedback linearization concept and its main goal is improvement of transient stability and voltage regulation at post-fault conditions. It will be shown that the controller enhances first swing stability and system damping under large disturbances as well as improves terminal voltage regulation. The response of the system is simulated on a test system in the presence of three-phase short circuit at terminal of the synchronous generator and compared to the performance of the standard IEEE type-1 voltage regulator, PSS and PID speed regulator. (author)
Kwon, Y.
2015-12-01
Large-scale patterns of woody plant species diversity have long been studied yet it is still one of the most controversial issues in biogeography. At continental to global scale, energy availability measured by potential evapotranspiration (PET) (i.e. PET-only model) and related water-energy dynamics model (i.e. Wang's model based on China's woody plant richness) has been two primary determinants for species richness. We identified several issues in existing modeling approaches that 1) species richness are derived from species range map not a plot data, 2) they over-predicted richness in Florida peninsular at the cost of R square values for better overall model fit and 3) they lack thorough examination for spatial autocorrelation of residuals. The plot-level forest inventory and analysis (FIA) program data set (total 2,745,363 tally trees from 79,145 ground plots in the eastern US forest) used for species richness showed different pattern to range-map based richness. We applied Elastic-Net regularization for variable selections then used spatial Poisson Generalized Linear Model (GLM) and to handle spatial autocorrelations. Elastic-Net approach produced Frost frequency days (FRS), PET, AET, and seasonality of precipitation (PSN, defined as the coefficient of variation of monthly mean precipitation) as best explanatory variables and produced good model fit (R2 of 0.67) without over-prediction for Florida peninsular. Partial regression revealed that PSN successfully accounted for very low species richness in Florida. The seasonality of precipitation as climatic variability explained climatic stability permitted species specialization than greater seasonality. Also, we compared our best model with two other richness models (i.e. PET-only and Wang's model) and demonstrated that spatial autocorrelation was highest for the use of just PET-only, intermediate for Wang's model, and lowest for ours.
Shapovalova, A. I.; Popović, L. Č.; Chavushyan, V. H.; Burenkov, A. N.; Ilić, D.; Kollatschny, W.; Kovačević, A.; Valdés, J. R.; Patiño-Álvarez, V.; León-Tavares, J.; Torrealba, J.; Zhdanova, V. E.
2016-02-01
We report the results of the first long-term (1990-2014) optical spectrophotometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift, high-luminosity, radio-quiet quasar. In the monitored period, the continua and Hγ fluxes changed about two times, while the Hβ flux changed about 1.4 times. We found periodical variations in the photometric flux with periods of 1200, 1850, and 4000 days, and 4500-day periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, buts with small significance level, while the 1850-day period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s-1. However, Hβ shows a broader mean profile and has a larger time lag (τ ˜ 120 days) than Hγ (τ ˜ 60 days). We estimate that the mass of the black hole is ˜2.6 × 109 M⊙. The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of the broad lines, we discuss a scenario where dense, gas-rich, cloudy-like structures are orbiting around a recoiling black hole.
Kılıç, Selim
2013-01-01
Linear regression is an approach to modeling the association between a numeric dependent variable y and one or more independent variables denoted X. The case of one explanatory variable in regression model is called simple linear regression. For more than one explanatory variable, then the model is called multiple linear regression. The dependent variable should be a numeric variable in linear regression. It is recommended at least 10 times as many cases as the number of independent variables...
Qiao, Ming; Li, Chengzhou; Liu, Yihe; Wang, Yuru; Li, Zhaoji; Zhang, Bo
2016-05-01
A novel triple reduced surface field (RESURF) lateral double-diffused metal oxide semiconductor field effect transistor (LDMOS) with partial linear variable doping (LVD) N-type top (N-top) layer is proposed in this paper. Compared with the conventional triple RESURF LDMOS, a partial LVD N-top layer is introduced in the surface of N-well, providing a low on-resistance conduction path and leading to an optimized surface electric field, which alleviates the inherent tradeoff between the breakdown voltage (BV) and specific on-resistance (Ron,sp). With the n-drift region length of 70 μm, the novel triple RESURF LDMOS obtains a high BV of 847 V and a low Ron,sp of 79 mΩ cm2 which are 76 V higher and 46 mΩ cm2 lower than those of the conventional triple RESURF LDMOS. Therefore, the novel triple RESURF LDMOS can greatly improve the tradeoff between BV and Ron,sp. Furthermore, compared with the other existing technologies in the high BV level, the novel triple RESURF LDMOS can achieve a highest figure of merit (FOM, defined as BV2/Ron,sp) of 9.08 MW/cm2 and the conventional RESURF silicon limits are broken.
Emadi, Arvin; Wu, Huaiwen; de Graaf, Ger; Wolffenbuttel, Reinoud
2012-01-01
In this paper the concept of a microspectrometer based on a Linear Variable Optical Filter (LVOF) for operation in the visible spectrum is presented and used in two different designs: the first is for the narrow spectral band between 610 nm and 680 nm, whereas the other is for the wider spectral band between 570 nm and 740 nm. Design considerations, fabrication and measurement results of the LVOF are presented. An iterative signal processing algorithm based on an initial calibration has been implemented to enhance the spectral resolution. Experimental validation is based on the spectrum of a Neon lamp. The results of measurements have been used to analyze the operating limits of the concept and to explain the sources of error in the algorithm. It is shown that the main benefits of a LVOF-based microspectrometer are in case of implementation in a narrowband application. The realized LVOF microspectrometers show a spectral resolution of 2.2 nm in the wideband design and 0.7 nm in the narrowband design. PMID:22274371
甘智华; 王龙一; 刘东立; 马潇辉; 邱利民
2012-01-01
Experiment between linear variable displacement transducer method and RC load method was carried out based on a linear compressor. Experiment results show that PV power at the compressor outlet (inlet of a regenerator) obtained by RC approach is 5%-20% lower than the PV power on piston face obtained by linear variable displacement transducer method.%针对一台线性压缩机,分别采用LVDT和RC负载法进行了实验研究,实验结果表明:采用RC负载法测量得到的压缩机出口(即回热器入口)PV功与LVDT测量得到的活塞端面PV功之差,占整个输入电功的5％ -20％,进一步减小了线性压缩机损失.
Futao Guo; Guangyu Wang; John L Innes; Xiangqing Ma; Long Sun; Haiqing Hu
2015-01-01
The purpose of this study was to determine a suitable model for investigating the effects of climate factors on the area burned by forest fire in the Tahe forest region, Daxing’an Mountains, in northeast China. The response variables were the area burned by lightning-caused fire, human-caused fire, and total burned area. The predictor variables were nine climate variables collected from the local weather station. Three regression models were utilized, including multiple linear regression, log-linear model (log-transformation on both response and predictor variables), and gamma-generalized linear model. The goodness-of-fit of the models were compared based on model fitting statistics such as R2, AIC, and RMSE. The results revealed that the gamma-generalized linear model was generally superior to both multiple linear regression model and log-linear model for fitting the fire data. Further, the best models were selected based on the criteria that the climate variables were statistically significant at a=0.05. The gamma best models indicated that maximum wind speed, precipitation, and days that rainfall greater than 0.1 mm had significant impacts on the area burned by the lightning-caused fire, while the mean temperature and minimum relative humidity were the main drivers of the burned area caused by human activities. Overall, the total burned area by forest fire was significantly influenced by days that rainfall greater than 0.1 mm and minimum rela-tive humidity, indicating that the moisture condition of forest stands determine the burned area by forest fire.
SHEN Shou-Feng; ZHANG Jun; PAN Zu-Liang
2005-01-01
By using a Backlund transformation and the multi-linear variable separation approach, we find a new generalsolution ofa (2+1)-dimensional generalization of the nonlinear Schrodinger system. The new "universal" formula is defined, and then, rich coherent structures can be found by selecting corresponding functions appropriately.
Osborn, John C
2013-01-01
ABSTRACT The Candidate is an attempt to marry elements of journalism and gaming into a format that both entertains and educates the player. The Google-AP Scholarship, a new scholarship award that is given to several journalists a year to work on projects at the threshold of technology and journalism, funded the project. The objective in this prototype version of the game is to put the player in the shoes of a congressional candidate during an off-year election, specificall...
Yang, Qin; Zou, Hong-Yan; Zhang, Yan; Tang, Li-Juan; Shen, Guo-Li; Jiang, Jian-Hui; Yu, Ru-Qin
2016-01-15
Most of the proteins locate more than one organelle in a cell. Unmixing the localization patterns of proteins is critical for understanding the protein functions and other vital cellular processes. Herein, non-linear machine learning technique is proposed for the first time upon protein pattern unmixing. Variable-weighted support vector machine (VW-SVM) is a demonstrated robust modeling technique with flexible and rational variable selection. As optimized by a global stochastic optimization technique, particle swarm optimization (PSO) algorithm, it makes VW-SVM to be an adaptive parameter-free method for automated unmixing of protein subcellular patterns. Results obtained by pattern unmixing of a set of fluorescence microscope images of cells indicate VW-SVM as optimized by PSO is able to extract useful pattern features by optimally rescaling each variable for non-linear SVM modeling, consequently leading to improved performances in multiplex protein pattern unmixing compared with conventional SVM and other exiting pattern unmixing methods. PMID:26592652
Kunz, V.C.; Borges, E.N.; Coelho, R.C.; Gubolino, L.A.; Martins, L.E.B.; Silva, E.
2012-01-01
The objectives of this study were to evaluate and compare the use of linear and nonlinear methods for analysis of heart rate variability (HRV) in healthy subjects and in patients after acute myocardial infarction (AMI). Heart rate (HR) was recorded for 15 min in the supine position in 10 patients with AMI taking β-blockers (aged 57 ± 9 years) and in 11 healthy subjects (aged 53 ± 4 years). HRV was analyzed in the time domain (RMSSD and RMSM), the frequency domain using low- and high-frequency bands in normalized units (nu; LFnu and HFnu) and the LF/HF ratio and approximate entropy (ApEn) were determined. There was a correlation (P < 0.05) of RMSSD, RMSM, LFnu, HFnu, and the LF/HF ratio index with the ApEn of the AMI group on the 2nd (r = 0.87, 0.65, 0.72, 0.72, and 0.64) and 7th day (r = 0.88, 0.70, 0.69, 0.69, and 0.87) and of the healthy group (r = 0.63, 0.71, 0.63, 0.63, and 0.74), respectively. The median HRV indexes of the AMI group on the 2nd and 7th day differed from the healthy group (P < 0.05): RMSSD = 10.37, 19.95, 24.81; RMSM = 23.47, 31.96, 43.79; LFnu = 0.79, 0.79, 0.62; HFnu = 0.20, 0.20, 0.37; LF/HF ratio = 3.87, 3.94, 1.65; ApEn = 1.01, 1.24, 1.31, respectively. There was agreement between the methods, suggesting that these have the same power to evaluate autonomic modulation of HR in both AMI patients and healthy subjects. AMI contributed to a reduction in cardiac signal irregularity, higher sympathetic modulation and lower vagal modulation. PMID:22370707
V.C. Kunz
2012-05-01
Full Text Available The objectives of this study were to evaluate and compare the use of linear and nonlinear methods for analysis of heart rate variability (HRV in healthy subjects and in patients after acute myocardial infarction (AMI. Heart rate (HR was recorded for 15 min in the supine position in 10 patients with AMI taking β-blockers (aged 57 ± 9 years and in 11 healthy subjects (aged 53 ± 4 years. HRV was analyzed in the time domain (RMSSD and RMSM, the frequency domain using low- and high-frequency bands in normalized units (nu; LFnu and HFnu and the LF/HF ratio and approximate entropy (ApEn were determined. There was a correlation (P < 0.05 of RMSSD, RMSM, LFnu, HFnu, and the LF/HF ratio index with the ApEn of the AMI group on the 2nd (r = 0.87, 0.65, 0.72, 0.72, and 0.64 and 7th day (r = 0.88, 0.70, 0.69, 0.69, and 0.87 and of the healthy group (r = 0.63, 0.71, 0.63, 0.63, and 0.74, respectively. The median HRV indexes of the AMI group on the 2nd and 7th day differed from the healthy group (P < 0.05: RMSSD = 10.37, 19.95, 24.81; RMSM = 23.47, 31.96, 43.79; LFnu = 0.79, 0.79, 0.62; HFnu = 0.20, 0.20, 0.37; LF/HF ratio = 3.87, 3.94, 1.65; ApEn = 1.01, 1.24, 1.31, respectively. There was agreement between the methods, suggesting that these have the same power to evaluate autonomic modulation of HR in both AMI patients and healthy subjects. AMI contributed to a reduction in cardiac signal irregularity, higher sympathetic modulation and lower vagal modulation.
Thukral, Kanika; Vijayan, N; Haranath, D; Jayaramakrishnan, V; Philip, J; Sreekanth, P; Bhagavannaryana, G
2015-12-01
Single crystal of l-Asparagine Monohydrate, an organic material has been successfully grown by slow evaporation solution growth technique at ambient condition. The lattice parameters and its strain of the grown crystal have been evaluated from powder X-ray diffraction and found that it belongs to orthorhombic crystal system. The polarizability has been measured by using the Clausius-Mossotti relation. The crystalline perfection of grown single crystal has been examined by high resolution X-ray diffraction and its imperfection in the diffraction plane was clearly visible by recording topographical image of the plane. From the high resolution XRD, it confirms that the crystal contained high crystalline perfection. The optical behavior was analyzed by photoluminescence and birefringence methods. In the photoluminescence, a broad peak has been observed at 475 nm which suggest that it emits blue light. The decay tendency of the material has also been observed by calculating decay constant. The optical homogeneity has been determined by the dispersion pattern of the material. The two photon absorption coefficient was further calculated by Z-scan, which gives the information about the third order non linear optical behavior of the material. The value of two-photon absorption coefficient is 4.25 × 10(-12)m/W. The thermal parameters like thermal effusivity, thermal diffusivity, specific heat and thermal conductivity was obtained by using photopyroelectric technique. The ferroelectric behavior of the grown specimen was analyzed from PE (polarization VS electric field) loop. The loop suggests that the material was a nearly equivalent to ideal capacitor. PMID:26148830
A linear gate providing a variable gate duration from 0,40μsec to 4μsec was developed. The electronic circuity consists of a linear circuit and an enable circuit. The input signal can be either unipolar or bipolar. If the input signal is bipolar, the negative portion will be filtered. The operation of the linear gate is controlled by the application of a positive enable pulse. (author)
Martin Wittenberg
2005-01-01
We analyse models in which additional "controls" or proxies are included in a regression. This might occur intentionally if there is significant measurement error in a key regressor or if a key variable is not measured at all. We develop a test of the hypothesis that a subset of the regressors are all proxying for the same latent variable and we show how an estimate of the structural coefficient might be obtained more efficiently than is available in the current literature. We apply the proce...
Cottle, J'Neil; Covey, Kevin R.; Ford Schlafly, Edward; Arce, Hector G.; Borissova, Jura; Downes, Juan Jose; Feigelson, Eric; Getman, Konstantin V.; Kim, Jinyoung Serena; Roman-Lopes, Alexandre; Roman-Zuniga, Carlos G.; Stringfellow, Guy S.; Ybarra, Jason E.; Chojnowski, S. Drew; Frinchaboy, Peter M.; Hearty, Fred R.; Majewski, Steven R.; Skrutskie, Michael F.; Stassun, Keivan; Wilson, John C.; Zasowski, Gail
2016-01-01
Precise measurements of the intrinsic (e.g., T_eff & log g) and dynamical (e.g, radial velocity & v sin i) properties of young stars provide important constraints for models of star formation and early stellar evolution. The APOGEE-2 YSO Young Cluster Program aims to measure the dynamics and star formation history uniformly across the full extent of the Orion star forming complex, based on thousands of high-resolution H-band spectra that APOGEE-2 will obtain of candidate Orion members. We utilize data from wide-field photometric surveys to select candidate YSOs throughout Orion via two complementary techniques. We follow the Koenig et al. (2014) criteria by using WISE+2MASS data to identify YSOs with IR excesses due to warm circumstellar dust; we also use multi-epoch optical PanSTARRS photometry to identify variable YSOs both with and without circumstellar disks (or circumstellar materials). The IR excess technique identifies 1729 candidates brighter than H=12.8 mag, a limit selected to ensure a minimum S/N > 50 for a typical 3-hour APOGEE exposure. selecting sources which display significant variability in at least 3 PanSTARRS bands similarly produces a preliminary sample of 1500 candidates with H<12.8 mag. In total, we identify nearly 2700 YSO candidates, 450 of which were identified via both selection methods. The resulting catalog exhibits clear spatial over-densities associated with known sub-regions of Orion such as the ONC, sigma Ori and L1641, and provides a uniform catalog for spectroscopic targeting over Orion's full 250+ sq. degree footprint.
Dralle, David N.; Boisramé, Gabrielle F. S.; Thompson, Sally E.
2014-11-01
The linearized hillslope Boussinesq equation, introduced by Brutsaert (1994), describes the dynamics of saturated, subsurface flow from hillslopes with shallow, unconfined aquifers. In this paper, we use a new analytical technique to solve the linearized hillslope Boussinesq equation to predict water table dynamics and hillslope discharge to channels. The new solutions extend previous analytical treatments of the linearized hillslope Boussinesq equation to account for the impact of spatiotemporal heterogeneity in water table recharge. The results indicate that the spatial character of recharge may significantly alter both steady state subsurface storage characteristics and the transient hillslope hydrologic response, depending strongly on similarity measures of controls on the subsurface flow dynamics. Additionally, we derive new analytical solutions for the linearized hillslope-storage Boussinesq equation and explore the interaction effects of recharge structure and hillslope morphology on water storage and base flow recession characteristics. A theoretical recession analysis, for example, demonstrates that decreasing the relative amount of downslope recharge has a similar effect as increasing hillslope convergence. In general, the theory suggests that recharge heterogeneity can serve to diminish or enhance the hydrologic impacts of hillslope morphology.
durdukoca, şule fırat; Arıbaş, Sebahattin
2011-01-01
This study has been done to determine the learning styles of the teacher candidates who study at Inonu University, department of primary school education Primary School Teaching Programme in the fall term of the academic year 2009-2010 and to confirm that whether these learning styles become different or not according to social-economic factors. The sample of this study has been built up by the 260 students who attend Inonu University, Faculty of Education, Department of Primary School Educat...
Savić, Stevan; Milovanović, Boško; Lužanin, Zorana; Lazić, Lazar; Dolinaj, Dragan
2015-08-01
This paper presents an analysis of the homogenised mean maximum ( T max) and minimum ( T min) temperatures. The data used in the analysis were collected at eight stations in the Autonomous Province of Vojvodina (Serbia) during the 1949-2008 period. The trends obtained from the slopes of the regression lines using the least square method show 0.9 °C/60 years for T max and 1.1 °C/60 years for T min; the non-parametric Mann-Kendall test was used to determine the statistically significant increasing trends of these two extreme parameters. In this paper, we analyse the influence of the Vangengeim-Girs classification of atmospheric circulation on the T max and T min trends in the Autonomous Province of Vojvodina (Serbia) using linear and quadratic models based on the least square method. Linear stepwise regression and the forward method reveal the highest dependence of T max and T min when the W or E circulation types are included in the model. Non-linear models show a greater contribution of T max and T min at W, E and C circulation types, respectively. The correction of the variance contribution of quadratic models ranges from approximately 16 to 44 % for T max and 32 to 38 % for T min.
Johnston, Kyle B
2016-01-01
With the advent of digital astronomy, new benefits and new problems have been presented to the modern day astronomer. While data can be captured in a more efficient and accurate manor using digital means, the efficiency of data retrieval has led to an overload of scientific data for processing and storage. This paper will focus on the construction and application of a supervised pattern classification algorithm for the identification of variable stars. Given the reduction of a survey of stars into a standard feature space, the problem of using prior patterns to identify new observed patterns can be reduced to time tested classification methodologies and algorithms. Such supervised methods, so called because the user trains the algorithms prior to application using patterns with known classes or labels, provide a means to probabilistically determine the estimated class type of new observations. This paper will demonstrate the construction and application of a supervised classification algorithm on variable sta...
Liu, W.; Lin, S.
2008-01-01
A simultaneous confidence band provides useful information on the plausible range of the unknown regression model. Construction of a simultaneous confidence band has a history going back to Working and Hotelling (1929) and is often a hard problem when the region over which a confidence band is required is restricted and the number of predictor variables is more than one. This article considers the construction of exact one-sided and two-sided simultaneous confidence bands of hyperbolic shape ...
JHANKAL ANUJ
2015-01-01
Full Text Available MHD boundary layer flow near stagnation point of linear stretching sheet with variable thermal conductivity are solved using He’s Homotopy Perturbation Method (HPM, which is one of the semi-exact method. Similarity transformation has been used to reduce the governing differential equations into an ordinary non-linear differential equation. The main advantage of HPM is that it does not require the small parameter in the equations and hence the limitations of traditional perturbations can be eliminated. In this paper firstly, the basic idea of the HPM for solving nonlinear differential equations is briefly introduced and then it is employed to derive solution of nonlinear governing equations of MHD boundary layer flow with nonlinear term. The influence of various relevant physical characteristics are presented and discussed.
Murat TEKİN
2009-12-01
Full Text Available The aim of this study is to investigate the physical education teacher candidates’ sex, class, mother and father learning and the democratic approach levels according to various variability’s. The sample of the study consists of 163 girls and 135 boys, totally 298 students from 1st 2nd 3rd and 4th classes, students who study at the department of physical education and sports teacher of Selçuk University and Karamanoğlu Mehmetbey University.First of all available information’s related to aim of study were given by consulting the scanned literature. Therefore, a theoretical frame which is about the topic was done. Secondly; democratic approach levels which developed by Gözütok (199518 was used. On the analyzing and commenting, to determine differences; t test, one Way ANOVA (one way variance analyze were used and to determine the difference between the groups tukey test was used and P< 0,05 significance was received. SPSS (Statistical package for social sciences was used to assess the data assessment and finding the calculated the values. Cronbah alpha 0,78As a result of this study; the teacher candidates who study at physical education and sport academy; sex and father and mother’s variant standard of learning; as there is a meaningful difference; according to class variant there is no differences. Key words : Physical Education, Teacher Candidate, Democratic Approach.
S Sarah; Gh Jeelani; Shakeel Ahmed
2011-06-01
This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the KashmirValley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Resultsindicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO3, Mg–HCO3 and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca2+, Mg2+, Na+, K+, NO3 and HCO$^{−}_{3}$, CO3 and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO3 concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.
Şeker, Murat; Zergeroğlu, Erkan; Tatlicioğlu, Enver
2016-01-01
In this study, a robust backstepping approach for the control problem of the variable-speed wind turbine with a permanent magnet synchronous generator is presented. Specifically, to overcome the negative effects of parametric uncertainties in both mechanical and electrical subsystems, a robust controller with a differentiable compensation term is proposed. The proposed methodology ensures the generator velocity tracking error to uniformly approach a small bound where practical tracking is achieved. Stability of the overall system is ensured by Lyapunov-based arguments. Comparative simulation studies with a standard proportional-integral-type controller are performed to illustrate the effectiveness, feasibility and efficiency of the proposed controller.
Torres Silva dos Santos, Alexandre; Moisés Santos e Silva, Cláudio
2013-01-01
Wind speed analyses are currently being employed in several fields, especially in wind power generation. In this study, we used wind speed data from records of Universal Fuess anemographs at an altitude of 10 m from 47 weather stations of the National Institute of Meteorology (Instituto Nacional de Meteorologia-INMET) from January 1986 to December 2011. The objective of the study was to investigate climatological aspects and wind speed trends. To this end, the following methods were used: filling of missing data, descriptive statistical calculations, boxplots, cluster analysis, and trend analysis using the Mann-Kendall statistical method. The seasonal variability of the average wind speeds of each group presented higher values for winter and spring and lower values in the summer and fall. The groups G1, G2, and G5 showed higher annual averages in the interannual variability of wind speeds. These observed peaks were attributed to the El Niño and La Niña events, which change the behavior of global wind circulation and influence wind speeds over the region. Trend analysis showed more significant negative values for the G3, G4, and G5 groups for all seasons of the year and in the annual average for the period under study. PMID:24250267
Röken, Christian; Schöneberg, Sebastian; Schuppan, Florian
2016-01-01
A leptonic one-zone model accounting for the radiation emission of blazars is presented. This model describes multiple successive injections of mono-energetic, ultra-relativistic, interacting electron populations, which are subjected to synchrotron and synchrotron-self Compton radiative losses. The electron number density is computed analytically by solving a time-dependent, relativistic transport equation. Moreover, the synchrotron and synchrotron-self Compton intensities as well as the corresponding total fluences are explicitly calculated. The lightcurves and fluences are plotted for realistic parameter values, showing that the model can simultaneously explain both the specific short-time variability in the flaring of blazars and the characteristic broad-band fluence behavior.
M. Bhuvaneswari
2015-01-01
Full Text Available The present study analyzed convective heat transfer and fluid flow characteristics of nanofluid in a two-dimensional square cavity under different combinations of thermophysical models of nanofluids. The right vertical wall temperature is varying linearly with height and the left wall is maintained at low temperature whereas the horizontal walls are adiabatic. Finite volume method is used to solve the governing equations. Two models are considered to calculate the effective thermal conductivity of the nanofluid and four models are considered to calculate the effective viscosity of the nanofluid. Numerical solutions are carried out for different combinations of effective viscosity and effective thermal conductivity models with different volume fractions of nanoparticles and Rayleigh numbers. It is found that the heat transfer rate increases for Models M1 and M3 on increasing the volume fraction of the nanofluid, whereas heat transfer rate decreases for Model M4 on increasing the volume fraction of the nanoparticle. The difference among the effective dynamic viscosity models of nanofluid plays an important role here such that the average Nusselt number demonstrates an increasing or decreasing trend with the concentration of nanoparticle.
Shapovalova, A I; Chavushyan, V H; Burenkov, A N; Ilic, D; Kollatschny, W; Kovacevic, A; Valdes, J R; Patino-Alvarez, V; Leon-Tavares, J; Torrealba, J; Zhdanova, V E
2016-01-01
We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and H$\\gamma$ fluxes changed for around two times, while the H$\\beta$ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s$^{-1}$. However, H$\\beta$ shows broade...
Corbet, R.H.D.; Charles, P.A.; Honey, W.B.; Smale, A.P.; Thorstensen, J.R.; Menzies, J.W.
1987-08-15
Results are presented of extensive CCD optical photometry (over 1000 frames representing approx. 150 hr of integration time) of the optical counterpart of the X-ray source GX339-4 obtained during the high (soft) state. The source was seen to be significantly variable. We do not, however, detect any periodic modulation with semi-amplitude greater than approx. 0.03 mag for periods less than approx. 0.5 day or semi-amplitude greater than approx. 0.07 mag for longer periods. An optical spectrum obtained shortly after GX339-4 made a transition from a 'low' to a 'high' state is also presented and compared with previous results.
Minar Naomi Damanik-Ambarita
2016-07-01
Full Text Available The biotic integrity of the Guayas River basin in Ecuador is at environmental risk due to extensive anthropogenic activities. We investigated the potential impacts of hydromorphological and chemical variables on biotic integrity using macroinvertebrate-based bioassessments. The bioassessment methods utilized included the Biological Monitoring Working Party adapted for Colombia (BMWP-Col and the average score per taxon (ASPT, via an extensive sampling campaign that was completed throughout the river basin at 120 sampling sites. The BMWP-Col classification ranged from very bad to good, and from probable severe pollution to clean water based on the ASPT scores. Generalized linear models (GLMs and sensitivity analysis were used to relate the bioassessment index to hydromorphological and chemical variables. It was found that elevation, nitrate-N, sediment angularity, logs, presence of macrophytes, flow velocity, turbidity, bank shape, land use and chlorophyll were the key environmental variables affecting the BMWP-Col. From the analyses, it was observed that the rivers at the upstream higher elevations of the river basin were in better condition compared to lowland systems and that a higher flow velocity was linked to a better BMWP-Col score. The nitrate concentrations were very low in the entire river basin and did not relate to a negative impact on the macroinvertebrate communities. Although the results of the models provided insights into the ecosystem, cross fold model development and validation also showed that there was a level of uncertainty in the outcomes. However, the results of the models and sensitivity analysis can support water management actions to determine and focus on alterable variables, such as the land use at different elevations, monitoring of nitrate and chlorophyll concentrations, macrophyte presence, sediment transport and bank stability.
Hutka, Stefanie; Bidelman, Gavin M.; Moreno, Sylvain
2013-01-01
There is convincing empirical evidence for bidirectional transfer between music and language, such that experience in either domain can improve mental processes required by the other. This music-language relationship has been studied using linear models (e.g., comparing mean neural activity) that conceptualize brain activity as a static entity. The linear approach limits how we can understand the brain’s processing of music and language because the brain is a nonlinear system. Furthermore, there is evidence that the networks supporting music and language processing interact in a nonlinear manner. We therefore posit that the neural processing and transfer between the domains of language and music are best viewed through the lens of a nonlinear framework. Nonlinear analysis of neurophysiological activity may yield new insight into the commonalities, differences, and bidirectionality between these two cognitive domains not measurable in the local output of a cortical patch. We thus propose a novel application of brain signal variability (BSV) analysis, based on mutual information and signal entropy, to better understand the bidirectionality of music-to-language transfer in the context of a nonlinear framework. This approach will extend current methods by offering a nuanced, network-level understanding of the brain complexity involved in music-language transfer. PMID:24454295
Zhang, Da; She, Jin; Yang, Jun; Yu, Mengsun
2015-06-01
Acute hypoxia activates several autonomic mechanisms, mainly in cardiovascular system and respiratory system. The influence of acute hypoxia on linear and nonlinear heart rate variability (HRV) has been studied, but the parameters in the process of hypoxia are still unclear. Although the changes of HRV in frequency domain are related to autonomic responses, how nonlinear dynamics change with the decrease of ambient atmospheric pressure is unknown either. Eight healthy male subjects were exposed to simulated altitude from sea level to 3600 m in 10 min. HRV parameters in frequency domain were analyzed by wavelet packet transform (Daubechies 4, 4 level) followed by Hilbert transform to assess the spectral power of modified low frequency (0.0625-0.1875 Hz, LFmod), modified high frequency (0.1875-0.4375 Hz, HFmod), and the LFmod/HFmod ratio in every 1 min. Nonlinear parameters were also quantified by sample entropy (SampEn) and short term fractal correlation exponent (α1) in the process. Hypoxia was associated with the depression of both LFmod and HFmod component. They were significantly lower than that at sea level at 3600 m and 2880 m respectively (both p altitude. Monitoring linear and nonlinear HRV parameters continuously in the process of hypoxia would be an effective way to evaluate the different regulatory mechanisms of autonomic nervous system. PMID:26088333
StefanieAndreaHutka
2013-12-01
Full Text Available There is convincing empirical evidence for bidirectional transfer between music and language, such that experience in either domain can improve mental processes required by the other. This music-language relationship has been studied using linear models (e.g., comparing mean neural activity that conceptualize brain activity as a static entity. The linear approach limits how we can understand the brain’s processing of music and language because the brain is a nonlinear system. Furthermore, there is evidence that the networks supporting music and language processing interact in a nonlinear manner. We therefore posit that the neural processing and transfer between the domains of language and music are best viewed through the lens of a nonlinear framework. Nonlinear analysis of neurophysiological activity may yield new insight into the commonalities, differences, and bidirectionality between these two cognitive domains not measurable in the local output of a cortical patch. We thus propose a novel application of brain signal variability (BSV analysis, based on mutual information and signal entropy, to better understand the bidirectionality of music-to-language transfer in the context of a nonlinear framework. This approach will extend current methods by offering a nuanced, network-level understanding of the brain complexity involved in music-language transfer.
Berdyugin, A; Sadegi, S; Tsygankov, S; Sakanoi, T; Kagitani, M; Yoneda, M; Okano, S; Poutanen, J
2016-01-01
We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained with the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and T60 (Haleakala, Hawaii, USA) remotely controlled telescopes during 31 observing nights. Polarimetry in the optical wavelengths has been complemented by observations in the X-rays with the SWIFT space observatory. Optical polarimetry revealed small intrinsic polarization in HD 48099 with 0.1% peak to peak variation over the orbital period of 3.08 days. The variability pattern is typical for binary systems, showing strong second harmonic of the orbital period. We apply our model code for the electron scattering in the circumstellar matter to put constraints on the system geometry. A good model fit is obtained for scattering of li...
Juliana Petrini
2012-12-01
Full Text Available The objective of this work was to assess the degree of multicollinearity and to identify the variables involved in linear dependence relations in additive-dominant models. Data of birth weight (n=141,567, yearling weight (n=58,124, and scrotal circumference (n=20,371 of Montana Tropical composite cattle were used. Diagnosis of multicollinearity was based on the variance inflation factor (VIF and on the evaluation of the condition indexes and eigenvalues from the correlation matrix among explanatory variables. The first model studied (RM included the fixed effect of dam age class at calving and the covariates associated to the direct and maternal additive and non-additive effects. The second model (R included all the effects of the RM model except the maternal additive effects. Multicollinearity was detected in both models for all traits considered, with VIF values of 1.03 - 70.20 for RM and 1.03 - 60.70 for R. Collinearity increased with the increase of variables in the model and the decrease in the number of observations, and it was classified as weak, with condition index values between 10.00 and 26.77. In general, the variables associated with additive and non-additive effects were involved in multicollinearity, partially due to the natural connection between these covariables as fractions of the biological types in breed composition.O objetivo deste trabalho foi avaliar o grau de multicolinearidade e identificar as variáveis envolvidas na dependência linear em modelos aditivo-dominantes. Foram utilizados dados de peso ao nascimento (n=141.567, peso ao ano (n=58.124 e perímetro escrotal (n=20.371 de bovinos de corte compostos Montana Tropical. O diagnóstico de multicolinearidade foi baseado no fator de inflação de variância (VIF e no exame dos índices de condição e dos autovalores da matriz de correlações entre as variáveis explanatórias. O primeiro modelo estudado (RM incluiu o efeito fixo de classe de idade da mãe ao parto e
Highlights of the LINEAR survey
Palaversa, Lovro
2015-01-01
Lincoln Near-Earth Asteroid Research asteroid survey (LINEAR) observed approximately 10,000 deg$^2$ of the northern sky in the period roughly from 1998 to 2013. Long baseline of observations combined with good cadence and depth ($14.5 < r_{SDSS}< 17.5$) provides excellent basis for investigation of variable and transient objects in this relatively faint and underexplored part of the sky. Details covering the repurposing of this survey for use in time domain astronomy, creation of a highly reliable catalogue of approximately 7,200 periodically variable stars (RR Lyrae, eclipsing binaries, SX Phe stars and LPVs) as well as search for optical signatures of exotic transient events (such as tidal disruption event candidates), are presented.
If the prediction of seismic events remains impossible up to now, to foresee damages experienced by a structure submitted to an earthquake becomes more and more relevant. It is a well known fact that these damages depends both the nature of the earthquake and the structure characteristics. Then, for a given structure such as a precise building, the main parameter of the problem stays the earthquake nature. The characterisation of seismic movements lead to different representations of a signal from the simple accelerogram to the Acceleration Displacement Response Spectrum. From these representations searchers and engineers go on trying to define the damaging potential of an earthquake by performing calculations of what is called the DamagiPotential Index. This paper aims to characterise the dispersion of damage experienced by simple RC structures (columns and frames) according to different Damaging Potential Index in order to evaluate the relevance of these Index or their ability to foresee damage. The effects of non linearity, the correlation between different Damaging Potential and Damage Index, the influence of seismic level or Index value on the dispersion of damage are then tested in this study and presented hereafter to give an illustration of damage scatter due to seismic movement variability. (authors)
Variable Permanent Magnet Quadrupole
Mihara, T.; Iwashita, Y.; /Kyoto U.; Kumada, M.; /NIRS, Chiba; Spencer, C.M.; /SLAC
2007-05-23
A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments.
Berdyugin, A.; Piirola, V.; Sadegi, S.; Tsygankov, S.; Sakanoi, T.; Kagitani, M.; Yoneda, M.; Okano, S.; Poutanen, J.
2016-06-01
Aims: We investigate the structure of the O-type binary system HD 48099 by measuring linear polarization that arises due to light scattering process. High-precison polarimetry provides independent estimates of the orbital parameters and gives important information on the properties of the system. Methods: Linear polarization measurements of HD 48099 in the B, V and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained with the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and T60 (Haleakala, Hawaii, USA) remotely controlled telescopes during 31 observing nights. Polarimetry in the optical wavelengths has been complemented by observations in the X-rays with the Swift space observatory. Results: Optical polarimetry revealed small intrinsic polarization in HD 48099 with ~0.1% peak to peak variation over the orbital period of 3.08 d. The variability pattern is typical for binary systems, showing strong second harmonic of the orbital period. We apply our model code for the electron scattering in the circumstellar matter to put constraints on the system geometry. A good model fit is obtained for scattering of light on a cloud produced by the colliding stellar winds. The geometry of the cloud, with a broad distribution of scattering particles away from the orbital plane, helps in constraining the (low) orbital inclination. We derive from the polarization data the inclination i = 17° ± 2° and the longitude of the ascending node Ω = 82° ± 1° of the binary orbit. The available X-ray data provide additional evidence for the existence of the colliding stellar winds in the system. Another possible source of the polarized light could be scattering from the stellar photospheres. The models with circumstellar envelopes, or matter confined to the orbital plane, do not provide good constraints on the low inclination, better than i ≤ 27°, as is already suggested by the absence of eclipses. The
Qiao Ming; Zhuang Xiang; Wu Li-Juan; Zhang Wen-Tong; Wen Heng-Juan; Zhang Bo; Li Zhao-Ji
2012-01-01
Based on the theoretical and experimental investigation of a thin silicon layer (TSL) with linear variable doping (LVD) and further research on the TSL LVD with a multiple step field plate (MSFP),a breakdown voltage (BV) model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator (SOI) device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field (ENDIF),from which the reduced surface field (RESURF) condition is deduced.The drain in the centre of the device has a good self-isolation effect but the problem of the high voltage interconnection (HVI) line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET (nLDMOS) with MSFP is realized.The experimental breakdown voltage (BV) and specific on-resistance (Ron,sp) of the TSL LVD SOI device are 694 V and 21.3 Ω.mm2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively.
Handbook on linear motor application
This book guides the application for Linear motor. It lists classification and speciality of Linear Motor, terms of linear-induction motor, principle of the Motor, types on one-side linear-induction motor, bilateral linear-induction motor, linear-DC Motor on basic of the motor, linear-DC Motor for moving-coil type, linear-DC motor for permanent-magnet moving type, linear-DC motor for electricity non-utility type, linear-pulse motor for variable motor, linear-pulse motor for permanent magneto type, linear-vibration actuator, linear-vibration actuator for moving-coil type, linear synchronous motor, linear electromagnetic motor, linear electromagnetic solenoid, technical organization and magnetic levitation and linear motor and sensor.
Allard Marc-Antoine
2012-11-01
Full Text Available Abstract Background Lymphoid infiltration is a prognostic marker in solid tumors, such as colorectal, breast and lung carcinomas. However, lymphoid infiltration is heterogeneous and the reproducibility of quantification based on single counts within a tumor is very low. We aimed to develop a reproducible method for evaluating lymphoid infiltration in tumors. Methods Virtual slides were obtained from tissue sections from the localized colorectal carcinomas of 117 patients, stained for CD3 and CD45R0. We assessed the variation of lymphoid cell density by automatic counts in 1 mm-wide, 5 μm-long segments of the invasive front, along an axis 4 mm in length running perpendicular to the invasive front of the tumor. Results We plotted curves of the variation of lymphocyte density across the tumor front. Three distinct patterns emerged from this linear quantification of lymphocyte (LQLI. In pattern 1, there was a high density of lymphocytes within the tumor. In pattern 2, lymphocyte density peaked close to the invasive margin. In pattern 3, lymphocytes were diffusely distributed, at low density. It was possible to classify all the tumors studied, and interobserver reproducibility was excellent (kappa =0.9. By contrast, single counts of CD3+ cells on tissue microarrays were highly variable for a given LQLI pattern, confirming the heterogeneity of lymphoid infiltration within individual tumors. In univariate analysis, all pathologic features (stage, metastatic lymph node ratio (LNR, vascular embolism, perineural invasion, CD3+ cell density, LQLI patterns for CD3+ and CD45R0+ cells were found to have a significant effect on disease-free survival (DFS. In multivariate analysis, only the LQLI pattern for CD3+ cells (HR: 6.02; 95% CI: 2.74-13.18 and metastatic lymph node ratio (HR: 6.14; 95% CI: 2.32-16.2 were associated with DFS. Conclusion LQLI is an automated, reproducible method for the assessment of lymphoid infiltration. However, validation of its
Eberly, Lynn E
2007-01-01
This chapter describes multiple linear regression, a statistical approach used to describe the simultaneous associations of several variables with one continuous outcome. Important steps in using this approach include estimation and inference, variable selection in model building, and assessing model fit. The special cases of regression with interactions among the variables, polynomial regression, regressions with categorical (grouping) variables, and separate slopes models are also covered. Examples in microbiology are used throughout. PMID:18450050
Shit, G. C.; Sreeparna Majee
2014-01-01
An analysis has been made to investigate the effects of thermal radiation on the magnetohydrodynamic (MHD) flow and heat transfer over an inclined non-linear stretching sheet. The surface velocity of the stretching sheet and the transverse magnetic field are assumed to vary as a power function of the distance from the origin. The effect of internal heat generation/absorption is taken into account. The fluid viscosity is assumed to vary as an inverse linear function of temperature. A generaliz...
Stefanie Andrea Hutka; Bidelman, Gavin M.; Sylvain eMoreno
2013-01-01
There is convincing empirical evidence for bidirectional transfer between music and language, such that experience in either domain can improve mental processes required by the other. This music-language relationship has been studied using linear models (e.g., comparing mean neural activity) that conceptualize brain activity as a static entity. The linear approach limits how we can understand the brain’s processing of music and language because the brain is a nonlinear system. Furthermore, th...
Hutka, Stefanie; Bidelman, Gavin M.; Moreno, Sylvain
2013-01-01
There is convincing empirical evidence for bidirectional transfer between music and language, such that experience in either domain can improve mental processes required by the other. This music-language relationship has been studied using linear models (e.g., comparing mean neural activity) that conceptualize brain activity as a static entity. The linear approach limits how we can understand the brain’s processing of music and language because the brain is a nonlinear system. Furthermore, th...
Meel-van den Abeelen, Aisha S.S.; Simpson, David M.; Wang, Lotte J.Y.; Slump, Cornelis H; Zhang, Rong; Tarumi, Takashi; Rickards, Caroline A.; Payne, Stephen; Mitsis, Georgios D.; Kostoglou, Kyriaki; Marmarelis, Vasilis; Shin, Dae; Tzeng, Yu-Chieh; Ainslie, Philip N; Gommer, Erik
2014-01-01
Transfer function analysis (TFA) is a frequently used method to assess dynamic cerebral autoregulation (CA) using spontaneous oscillations in blood pressure (BP) and cerebral blood flow velocity (CBFV). However, controversies and variations exist in how research groups utilise TFA, causing high variability in interpretation. The objective of this study was to evaluate between-centre variability in TFA outcome metrics. 15 centres analysed the same 70 BP and CBFV datasets from healthy subjects ...
Highlights: • The Tau-Chebyshev method solves the linear fluid flow equations in spherical shells. • The fluid motion is driven by a central force proportional to the radial position. • The full Navier–Stokes equations are solved by the spectral element method. • The linear results are verified with the solution of the Navier–Stokes equations. • The solution of the linear problems is used to initiate non-linear calculations. -- Abstract: The onset of thermal convection in a non-rotating spherical shell is investigated using linear theory. The Tau-Chebyshev spectral method is used to integrate the linearized equations. We investigate the onset of thermal convection by considering two cases of the radial gravitational field (i) a local acceleration, acting radially inward, that is proportional to the distance from the center r, and (ii) a radial gravitational central force that is proportional to r−n. The former case has been widely analyzed in the literature, because it constitutes a simplified model that is usually used, in astrophysics and geophysics, and is studied here to validate the numerical method. The latter case was analyzed since the case n = 5 has been experimentally realized (by means of the dielectrophoretic effect) under microgravity condition, in the experimental container called GeoFlow, inside the International Space Station. Our study is aimed to clarify the role of (i) a radially inward central force (either proportional to r or to r−n), (ii) a base conductive temperature distribution provided by either a uniform heat source or an imposed temperature difference between outer and inner spheres, and (iii) the aspect ratio η (ratio of the radii of the inner and outer spheres), on the critical Rayleigh number. In all cases the surface of the spheres has been assumed to be rigid. The results obtained with the linear theory based on the Tau-Chebyshev spectral method are compared with those of the integration of the full non-linear
Remy, Pascal
2016-01-01
In this article, we investigate Gevrey and summability properties of formal power series solutions of certain classes of inhomogeneous linear integro-differential equations with analytic coefficients in a neighborhood of $(0,0)\\in\\mathbb{C}^{2}$. In particular, we give necessary and sufficient conditions under which these solutions are convergent or are k-summable, for a convenient positive rational number k, in a given direction.
G. C. Shit
2014-01-01
Full Text Available An analysis has been made to investigate the effects of thermal radiation on the magnetohydrodynamic (MHD flow and heat transfer over an inclined non-linear stretching sheet. The surface velocity of the stretching sheet and the transverse magnetic field are assumed to vary as a power function of the distance from the origin. The effect of internal heat generation/absorption is taken into account. The fluid viscosity is assumed to vary as an inverse linear function of temperature. A generalized similarity transformation is used to reduce the governing partial differential equations to a system of non-linear coupled ordinary differential equations, and is solved numerically by using a finite difference scheme. The numerical results concerned with the velocity, temperature and concentration distributions as well as the skin-friction coefficient and the Nusselt number for various values of the dimensionless parameters of interest are obtained. Some important findings reported in this paper reveal that the effect of thermal radiation and heat generation/absorption have significant role in controlling the rate of heat transfer in the boundary layer region.
Tantalum oxide coatings as candidate environmental barriers
Moldovan, Monica; Weyant, C. M.; Johnson, D. Lynn; Faber, K. T.
2004-01-01
Tantalum (Ta) oxide, due to its high-temperature capabilities and thermal expansion coefficient similar to silicon nitride, is a promising candidate for environmental barriers for silicon (Si) nitride-based ceramics. This paper focuses on the development of plasma-sprayed Ta oxide as an environmental barrier coating for silicon nitride. Using a D-optimal design of experiments, plasma-spray processing variables were optimized to maximize coating density. The effect of processing variables on c...
Colin, G.
2006-10-15
Spark ignition engine control has become a major issue for the compliance with emissions legislation while ensuring driving comfort. Engine down-sizing is one of the promising ways to reduce fuel consumption and resulting CO{sub 2} emissions. Combining several existing technologies such as supercharging and variable valve actuation, down-sizing is a typical example of the problems encountered in Spark Ignited (SI) engine control: nonlinear systems with saturation of actuators; numerous major physical phenomena not measurable; limited computing time; control objectives (consumption, pollution, performance) often competing. A methodology of modelling and model-based control (internal model and predictive control) for these systems is also proposed and applied to the air path of the down-sized engine. Models, physicals and generics, are built to estimate in-cylinder air mass, residual burned gases mass and air scavenged mass from the intake to the exhaust. The complete and generic engine torque control architecture for the turbo-charged SI engine with variable cam-shaft timing was tested in simulation and experimentally (on engine and vehicle). These tests show that new possibilities are offered in order to decrease pollutant emissions and optimize engine efficiency. (author)
杨俊华; 郑俭华; 杨梦丽; 吴捷
2012-01-01
在额定风速以上时,为保证风电机组的安全稳定运行,需要降低风力机捕获风能,使风力机的转速及功率维持在额定值,基于微分几何反馈线性化方法,提出变桨距风力发电机组恒功率控制策略.建立了风力机的仿射非线性模型,采用微分几何反馈线性化变换实现全局精确线性化；根据新的线性化模型,以风力机转速为输出反馈变量,叶片桨距角为输入控制变量,设计桨距角控制器;在风速高于额定值时调节风力机维持在额定转速,从而实现额定风速以上的恒功率控制.仿真结果表明,所提控制策略能较好地解决变桨距风力发电机组额定风速以上的恒功率控制问题,控制方法具有较好的适应性和鲁棒性.%When the wind speed exceeds the rated value, the wind power captured by the wind turbine must be reduced to guarantee the wind turbine to operate in the safe and stable status. A control scheme for limiting the power of the variable pitch wind turbine based on the differential geometry feedback linearized theory is proposed to keep the rotational speed and output power at the rated value. An affine nonlinear model of the wind turbine is developed and then globally exactly linearized by a differential geometry transformation. With the new linearized model, we design a novel pitch angle controller in which the output feedback variable is the rotational speed and the input control variable is the blade pitch angle. When the wind speed exceeds the rated value, the pitch angle controller changes the blade pitch angle to reduce the rotational speed back to the rated value for ensuring the constant output power. Simulation results show that, when the wind speed is above the rated value, the proposed control strategy effectively implements the constant output power control for the variable pitch wind turbine with fine flexibility and robustness.
This study was initiated to investigate, whether there are any radiation-induced changes in DNA-content and if these changes can be repaired. Seeds of Vicia faba L. were grown in glass culture vessels. After 10 to 20 days the seedings were irradiated using a 1 C1 60Co gammasource (90mrad/h and 33 rad/h) and a 5 mCi 252Cf neutronsource (90 mrad/h). Both, neutron and gamma irradiation cause a reduction in nuclear DNA-content even after low doses (1 to 10 rad). The extent of depression is only depending on linear energy transfer. Parallel to the induced minimum in DNA-content, but shifted to higher doses, also the mitotic activity reaches a minimum. Whereas neutron irradiation results in a total stop after doses of 8 rad, gamma-irradiation only induces a depression of 80 %. Whith higher doses the mitotic activity increases again. The neutron-induced changes in DNA-content seem to be restored within 90 minutes after irradiation. No continuous increase could be found after low gamma-doses. Gamma-irradiation with higher dose rates (60Co, 33 rad/h) causes a general decrease over the dose-range studied (100 to 1600 rad). Following doses of 100 rad the mitotic activity increases significantly. With higher doses the decrease is exponential. A dose-dependent mitotic delay could also be observed. As described by many authors, unscheduled DNA-synthesis (UDS) could not be detected in nuclei of Vicia faba. This indicates that an other system, perhaps acting in situ - at the damaged place - is responsible for the repair of radiation-induced thymine-damages. (Author)
Silke Dornieden
Full Text Available Alzheimer's disease (AD is a progressive neurodegenerative disorder with devastating effects. Currently, therapeutic options are limited to symptomatic treatment. For more than a decade, research focused on immunotherapy for the causal treatment of AD. However, clinical trials with active immunization using Aβ encountered severe complications, for example meningoencephalitis. Consequently, attention focused on passive immunization using antibodies. As an alternative to large immunoglobulins (IgGs, Aβ binding single-chain variable fragments (scFvs were used for diagnostic and therapeutic research approaches. scFvs can be expressed in E. coli and may provide improved pharmacokinetic properties like increased blood-brain barrier permeability or reduced side-effects in vivo. In this study, we constructed an scFv from an Aβ binding IgG, designated IC16, which binds the N-terminal region of Aβ (Aβ(1-8. scFv-IC16 was expressed in E. coli, purified and characterized with respect to its interaction with different Aβ species and its influence on Aβ fibril formation. We were able to show that scFv-IC16 strongly influenced the aggregation behavior of Aβ and could be applied as an Aβ detection probe for plaque staining in the brains of transgenic AD model mice. The results indicate potential for therapy and diagnosis of AD.
Heart rate variability (HRV) from the frequency domain and three calculations of entropy (En), approximate (ApEn), sample (SampEn) and Lempel–Ziv (LZEn), were assessed for intra- and inter-visit reproducibility from short-term recordings in persons with tetraplegia and neurologically intact controls. The intraclass correlation coefficient (ICC) was calculated for multiple comparisons to determine the reproducibility in both groups during a 4 h visit and across three visits. By ICC in both groups, ApEn, SampEn and LZEn possessed excellent intra- (≥0.87) and inter-visit reproducibility (≥0.90). In contrast, frequency domain measures were collectively less concise. In general on intra- and inter-visit comparisons for both groups, high frequency (HF) measures were more reliable than low frequency (LF). In control subjects relative to other units of expression, normalized units (nu) of LF had the best intra-visit reliability across all comparisons. This was not the case on inter-visit comparisons where absolute (≥0.74) and natural log (ln) (≥0.66) representations of LF were more reliable. In the group with tetraplegia, LFln was the most reliable for comparisons up to or including 180 min (≥0.60) and two visits (≥0.63). Thus, calculations of En and HF HRV appear to be more reliable than LF HRV and less confounded by small sample sizes
Linear Network Fractional Routing
S.ASOKAN,
2011-07-01
Full Text Available A Network is a finite directed acyclic graph with source messages from a fixed alphabet and message demands at sink nodes. Linear Programming is an algorithm design method. It can be used whenthe solution to a problem can be viewed as the result of a sequence of decisions. The Linear Programming model for the network problem where in every variable has a value one or zero. The problem is todetermine a method of transmitting the messages through the network such that all sink demands are satisfied. We will prove fractional routing capacity for some solvable network using Linear Programmingmodel.
Linear models: permutation methods
Cade, B.S.
2005-01-01
Permutation tests (see Permutation Based Inference) for the linear model have applications in behavioral studies when traditional parametric assumptions about the error term in a linear model are not tenable. Improved validity of Type I error rates can be achieved with properly constructed permutation tests. Perhaps more importantly, increased statistical power, improved robustness to effects of outliers, and detection of alternative distributional differences can be achieved by coupling permutation inference with alternative linear model estimators. For example, it is well-known that estimates of the mean in linear model are extremely sensitive to even a single outlying value of the dependent variable compared to estimates of the median [7, 19]. Traditionally, linear modeling focused on estimating changes in the center of distributions (means or medians). However, quantile regression allows distributional changes to be estimated in all or any selected part of a distribution or responses, providing a more complete statistical picture that has relevance to many biological questions [6]...
李笕列; 荣冈
2009-01-01
Mixed integer linear programming(MILP)approach for simultaneous gross error detection and data reconciliation has been proved as an efficient Way to adjust process data with material,energy,and other balance constrains.BUt the efficiency will decrease significantly when this method IS applied in a large-scale problem because there are too many binary variables involved.In this article, an improved method IS proposed in order to generate gross error candidates with reliability factors before data rectification.Candidates are used in the MILP objectivc function to improve the emciency and accuracy by reducing the number of binary variables and gwmg accurate weights for suspected gross errors candidates.Performance of this improved method IS compared and discussed by applying the algorithm in a widely used industrial example.
Ho, Yi-Lwun; Lin, Chen; Lin, Yen-Hung; Lo, Men-Tzung
2011-01-01
Aims The influences of nonstationarity and nonlinearity on heart rate time series can be mathematically qualified or quantified by multiscale entropy (MSE). The aim of this study is to investigate the prognostic value of parameters derived from MSE in the patients with systolic heart failure. Methods and Results Patients with systolic heart failure were enrolled in this study. One month after clinical condition being stable, 24-hour Holter electrocardiogram was recording. MSE as well as other standard parameters of heart rate variability (HRV) and detrended fluctuation analysis (DFA) were assessed. A total of 40 heart failure patients with a mea age of 56±16 years were enrolled and followed-up for 684±441 days. There were 25 patients receiving β-blockers treatment. During follow-up period, 6 patients died or received urgent heart transplantation. The short-term exponent of DFA and the slope of MSE between scale 1 to 5 were significantly different between patients with or without β-blockers (p = 0.014 and p = 0.028). Only the area under the MSE curve for scale 6 to 20 (Area6–20) showed the strongest predictive power between survival (n = 34) and mortality (n = 6) groups among all the parameters. The value of Area6–2021.2 served as a significant predictor of mortality or heart transplant (p = 0.0014). Conclusion The area under the MSE curve for scale 6 to 20 is not relevant to β-blockers and could further warrant independent risk stratification for the prognosis of CHF patients. PMID:21533258
Yi-Lwun Ho
Full Text Available AIMS: The influences of nonstationarity and nonlinearity on heart rate time series can be mathematically qualified or quantified by multiscale entropy (MSE. The aim of this study is to investigate the prognostic value of parameters derived from MSE in the patients with systolic heart failure. METHODS AND RESULTS: Patients with systolic heart failure were enrolled in this study. One month after clinical condition being stable, 24-hour Holter electrocardiogram was recording. MSE as well as other standard parameters of heart rate variability (HRV and detrended fluctuation analysis (DFA were assessed. A total of 40 heart failure patients with a mea age of 56±16 years were enrolled and followed-up for 684±441 days. There were 25 patients receiving β-blockers treatment. During follow-up period, 6 patients died or received urgent heart transplantation. The short-term exponent of DFA and the slope of MSE between scale 1 to 5 were significantly different between patients with or without β-blockers (p = 0.014 and p = 0.028. Only the area under the MSE curve for scale 6 to 20 (Area(6-20 showed the strongest predictive power between survival (n = 34 and mortality (n = 6 groups among all the parameters. The value of Area(6-2021.2 served as a significant predictor of mortality or heart transplant (p = 0.0014. CONCLUSION: The area under the MSE curve for scale 6 to 20 is not relevant to β-blockers and could further warrant independent risk stratification for the prognosis of CHF patients.
Vretenar, M
2014-01-01
The main features of radio-frequency linear accelerators are introduced, reviewing the different types of accelerating structures and presenting the main characteristics aspects of linac beam dynamics.
Cochran, Donna J.; Boutte, Alvin J.; Chen, Dakai; Pellish, Jonathan A.; Ladbury, Raymond L.; Casey, Megan C.; Campola, Michael J.; Wilcox, Edward P.; Obryan, Martha V.; LaBel, Kenneth A.; Lauenstein, Jean-Marie; Batchlor, David A.; Oldham, Timothy R.
2012-01-01
Vulnerability of a variety of candidate spacecraft electronics to total ionizing dose and displacement damage is studied. Devices tested include optoelectronics, digital, analog, linear, and hybrid devices.
Sparse Linear Identifiable Multivariate Modeling
Henao, Ricardo; Winther, Ole
2011-01-01
In this paper we consider sparse and identifiable linear latent variable (factor) and linear Bayesian network models for parsimonious analysis of multivariate data. We propose a computationally efficient method for joint parameter and model inference, and model comparison. It consists of a fully...... Bayesian hierarchy for sparse models using slab and spike priors (two-component δ-function and continuous mixtures), non-Gaussian latent factors and a stochastic search over the ordering of the variables. The framework, which we call SLIM (Sparse Linear Identifiable Multivariate modeling), is validated and...... computational complexity. We attribute this mainly to the stochastic search strategy used, and to parsimony (sparsity and identifiability), which is an explicit part of the model. We propose two extensions to the basic i.i.d. linear framework: non-linear dependence on observed variables, called SNIM (Sparse Non-linear...
Investigating Academic Achievements and Critical Thinking Dispositions of Teacher Candidates
Karagöl, Ibrahim; Bekmezci, Sinan
2015-01-01
The aim of this study is to examine the relationship between academic achievements and critical thinking dispositions of teacher candidates in Faculty of Education and to find out whether critical thinking dispositions and academic achievements scores of teacher candidates differ according to different variables. The population consists of the…
From November 28 to December 9, the Stanford Linear Accelerator Center hosted an International Workshop on Next Generation Linear Colliders. The attendance, including delegations from CERN, Frascati (Italy), KEK (Japan), Livermore (US), Novosibirsk (USSR), Drsay (France) and SLAC itself reflected the international interest in this new approach to higher energies
Analysis of MERCATOR data Part I: variable B stars
De Cat, P; Aerts, C; Goossens, K; Saesen, S; Cuypers, J; Yakut, K; Scuflaire, R; Dupret, M A; observers,; observers, many
2005-01-01
We re-classified 31 variable B stars which were observed more than 50 times in the Geneva photometric system with the P7 photometer attached to the MERCATOR telescope (La Palma) during its first 3 years of scientific observations. HD89688 is a possible beta Cephei/slowly pulsating B star hybrid and the main mode of the COROT target HD180642 shows non-linear effects. The Maia candidates are re-classified as either ellipsoidal variables or spotted stars. Although the mode identification is still ongoing, all the well-identified modes so far have a degree l = 0, 1 or 2.
One of the simplest, yet most profound, questions we can ask about the Universe is, how much stuff is in it, and further what is that stuff composed of? Needless to say, the answer to this question has very important implications for the evolution of the Universe, determining both the ultimate fate and the course of structure formation. Remarkably, at this late date in the history of the Universe we still do not have a definitive answer to this simplest of questions---although we have some very intriguing clues. It is known with certainty that most of the material in the Universe is dark, and we have the strong suspicion that the dominant component of material in the Cosmos is not baryons, but rather is exotic relic elementary particles left over from the earliest, very hot epoch of the Universe. If true, the Dark Matter question is a most fundamental one facing both particle physics and cosmology. The leading particle dark matter candidates are: the axion, the neutralino, and a light neutrino species. All three candidates are accessible to experimental tests, and experiments are now in progress. In addition, there are several dark horse, long shot, candidates, including the superheavy magnetic monopole and soliton stars. 13 refs
N.C. Lenin
2010-06-01
Full Text Available In this paper, the results of a finite element analysis are carried out on new stator geometry of a three phase longitudinal flux Linear Switched Reluctance Motor (LSRM. In the new geometry, pole shoes are affixed to the stator poles. Static and dynamic characteristics for the proposed structure have been highlighted. Motor performance for variable load conditions is discussed. The 2-Dimensional (2-D finite element analysis (FEA and the experimental results of this paper prove that LSRMs are one of the strong candidates for linear propulsion drive