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Sample records for general linear groups

  1. Applications of multivariate modeling to neuroimaging group analysis: A comprehensive alternative to univariate general linear model

    PubMed Central

    Chen, Gang; Adleman, Nancy E.; Saad, Ziad S.; Leibenluft, Ellen; Cox, RobertW.

    2014-01-01

    All neuroimaging packages can handle group analysis with t-tests or general linear modeling (GLM). However, they are quite hamstrung when there are multiple within-subject factors or when quantitative covariates are involved in the presence of a within-subject factor. In addition, sphericity is typically assumed for the variance–covariance structure when there are more than two levels in a within-subject factor. To overcome such limitations in the traditional AN(C)OVA and GLM, we adopt a multivariate modeling (MVM) approach to analyzing neuroimaging data at the group level with the following advantages: a) there is no limit on the number of factors as long as sample sizes are deemed appropriate; b) quantitative covariates can be analyzed together with within- subject factors; c) when a within-subject factor is involved, three testing methodologies are provided: traditional univariate testing (UVT)with sphericity assumption (UVT-UC) and with correction when the assumption is violated (UVT-SC), and within-subject multivariate testing (MVT-WS); d) to correct for sphericity violation at the voxel level, we propose a hybrid testing (HT) approach that achieves equal or higher power via combining traditional sphericity correction methods (Greenhouse–Geisser and Huynh–Feldt) with MVT-WS. PMID:24954281

  2. An algorithm for the construction of substitution box for block ciphers based on projective general linear group

    NASA Astrophysics Data System (ADS)

    Altaleb, Anas; Saeed, Muhammad Sarwar; Hussain, Iqtadar; Aslam, Muhammad

    2017-03-01

    The aim of this work is to synthesize 8*8 substitution boxes (S-boxes) for block ciphers. The confusion creating potential of an S-box depends on its construction technique. In the first step, we have applied the algebraic action of the projective general linear group PGL(2,GF(28)) on Galois field GF(28). In step 2 we have used the permutations of the symmetric group S256 to construct new kind of S-boxes. To explain the proposed extension scheme, we have given an example and constructed one new S-box. The strength of the extended S-box is computed, and an insight is given to calculate the confusion-creating potency. To analyze the security of the S-box some popular algebraic and statistical attacks are performed as well. The proposed S-box has been analyzed by bit independent criterion, linear approximation probability test, non-linearity test, strict avalanche criterion, differential approximation probability test, and majority logic criterion. A comparison of the proposed S-box with existing S-boxes shows that the analyses of the extended S-box are comparatively better.

  3. Comparing Multiple-Group Multinomial Log-Linear Models for Multidimensional Skill Distributions in the General Diagnostic Model. Research Report. ETS RR-08-35

    ERIC Educational Resources Information Center

    Xu, Xueli; von Davier, Matthias

    2008-01-01

    The general diagnostic model (GDM) utilizes located latent classes for modeling a multidimensional proficiency variable. In this paper, the GDM is extended by employing a log-linear model for multiple populations that assumes constraints on parameters across multiple groups. This constrained model is compared to log-linear models that assume…

  4. Generalized Linear Covariance Analysis

    NASA Technical Reports Server (NTRS)

    Carpenter, James R.; Markley, F. Landis

    2014-01-01

    This talk presents a comprehensive approach to filter modeling for generalized covariance analysis of both batch least-squares and sequential estimators. We review and extend in two directions the results of prior work that allowed for partitioning of the state space into solve-for'' and consider'' parameters, accounted for differences between the formal values and the true values of the measurement noise, process noise, and textita priori solve-for and consider covariances, and explicitly partitioned the errors into subspaces containing only the influence of the measurement noise, process noise, and solve-for and consider covariances. In this work, we explicitly add sensitivity analysis to this prior work, and relax an implicit assumption that the batch estimator's epoch time occurs prior to the definitive span. We also apply the method to an integrated orbit and attitude problem, in which gyro and accelerometer errors, though not estimated, influence the orbit determination performance. We illustrate our results using two graphical presentations, which we call the variance sandpile'' and the sensitivity mosaic,'' and we compare the linear covariance results to confidence intervals associated with ensemble statistics from a Monte Carlo analysis.

  5. Weil Representation of a Generalized Linear Group over a Ring of Truncated Polynomials over a Finite Field Endowed with a Second Class Involution

    NASA Astrophysics Data System (ADS)

    Gutiérrez Frez, Luis; Pantoja, José

    2015-09-01

    We construct a complex linear Weil representation ρ of the generalized special linear group G={SL}_*^{1}(2,A_n) (A_n=K[x]/< x^nrangle , K the quadratic extension of the finite field k of q elements, q odd), where A_n is endowed with a second class involution. After the construction of a specific data, the representation is defined on the generators of a Bruhat presentation of G, via linear operators satisfying the relations of the presentation. The structure of a unitary group U associated to G is described. Using this group we obtain a first decomposition of ρ.

  6. Quantization of general linear electrodynamics

    SciTech Connect

    Rivera, Sergio; Schuller, Frederic P.

    2011-03-15

    General linear electrodynamics allow for an arbitrary linear constitutive relation between the field strength 2-form and induction 2-form density if crucial hyperbolicity and energy conditions are satisfied, which render the theory predictive and physically interpretable. Taking into account the higher-order polynomial dispersion relation and associated causal structure of general linear electrodynamics, we carefully develop its Hamiltonian formulation from first principles. Canonical quantization of the resulting constrained system then results in a quantum vacuum which is sensitive to the constitutive tensor of the classical theory. As an application we calculate the Casimir effect in a birefringent linear optical medium.

  7. Removing an intersubject variance component in a general linear model improves multiway factoring of event-related spectral perturbations in group EEG studies.

    PubMed

    Spence, Jeffrey S; Brier, Matthew R; Hart, John; Ferree, Thomas C

    2013-03-01

    Linear statistical models are used very effectively to assess task-related differences in EEG power spectral analyses. Mixed models, in particular, accommodate more than one variance component in a multisubject study, where many trials of each condition of interest are measured on each subject. Generally, intra- and intersubject variances are both important to determine correct standard errors for inference on functions of model parameters, but it is often assumed that intersubject variance is the most important consideration in a group study. In this article, we show that, under common assumptions, estimates of some functions of model parameters, including estimates of task-related differences, are properly tested relative to the intrasubject variance component only. A substantial gain in statistical power can arise from the proper separation of variance components when there is more than one source of variability. We first develop this result analytically, then show how it benefits a multiway factoring of spectral, spatial, and temporal components from EEG data acquired in a group of healthy subjects performing a well-studied response inhibition task.

  8. Semi-Parametric Generalized Linear Models.

    DTIC Science & Technology

    1985-08-01

    is nonsingular, upper triangular, and of full rank r. It is known (Dongarra et al., 1979) that G-1 FT is the Moore - Penrose inverse of L . Therefore... GENERALIZED LINEAR pq Mathematics Research Center University of Wisconsin-Madison 610 Walnut Street Madison, Wisconsin 53705 TI C August 1985 E T NOV 7 8...North Carolina 27709 -. -.. . - -.-. g / 6 O5’o UNIVERSITY OF WISCONSIN-MADISON MATHD4ATICS RESEARCH CENTER SD4I-PARAMETRIC GENERALIZED LINEAR MODELS

  9. Small diameter symmetric networks from linear groups

    NASA Technical Reports Server (NTRS)

    Campbell, Lowell; Carlsson, Gunnar E.; Dinneen, Michael J.; Faber, Vance; Fellows, Michael R.; Langston, Michael A.; Moore, James W.; Multihaupt, Andrew P.; Sexton, Harlan B.

    1992-01-01

    In this note is reported a collection of constructions of symmetric networks that provide the largest known values for the number of nodes that can be placed in a network of a given degree and diameter. Some of the constructions are in the range of current potential engineering significance. The constructions are Cayley graphs of linear groups obtained by experimental computation.

  10. Linear and nonlinear generalized Fourier transforms.

    PubMed

    Pelloni, Beatrice

    2006-12-15

    This article presents an overview of a transform method for solving linear and integrable nonlinear partial differential equations. This new transform method, proposed by Fokas, yields a generalization and unification of various fundamental mathematical techniques and, in particular, it yields an extension of the Fourier transform method.

  11. Extended Generalized Linear Latent and Mixed Model

    ERIC Educational Resources Information Center

    Segawa, Eisuke; Emery, Sherry; Curry, Susan J.

    2008-01-01

    The generalized linear latent and mixed modeling (GLLAMM framework) includes many models such as hierarchical and structural equation models. However, GLLAMM cannot currently accommodate some models because it does not allow some parameters to be random. GLLAMM is extended to overcome the limitation by adding a submodel that specifies a…

  12. Stagewise generalized estimating equations with grouped variables.

    PubMed

    Vaughan, Gregory; Aseltine, Robert; Chen, Kun; Yan, Jun

    2017-02-13

    Forward stagewise estimation is a revived slow-brewing approach for model building that is particularly attractive in dealing with complex data structures for both its computational efficiency and its intrinsic connections with penalized estimation. Under the framework of generalized estimating equations, we study general stagewise estimation approaches that can handle clustered data and non-Gaussian/non-linear models in the presence of prior variable grouping structure. As the grouping structure is often not ideal in that even the important groups may contain irrelevant variables, the key is to simultaneously conduct group selection and within-group variable selection, that is, bi-level selection. We propose two approaches to address the challenge. The first is a bi-level stagewise estimating equations (BiSEE) approach, which is shown to correspond to the sparse group lasso penalized regression. The second is a hierarchical stagewise estimating equations (HiSEE) approach to handle more general hierarchical grouping structure, in which each stagewise estimation step itself is executed as a hierarchical selection process based on the grouping structure. Simulation studies show that BiSEE and HiSEE yield competitive model selection and predictive performance compared to existing approaches. We apply the proposed approaches to study the association between the suicide-related hospitalization rates of the 15-19 age group and the characteristics of the school districts in the State of Connecticut.

  13. Alternative approach to general coupled linear optics

    SciTech Connect

    Wolski, Andrzej

    2005-11-29

    The Twiss parameters provide a convenient description of beam optics in uncoupled linear beamlines. For coupled beamlines, a variety of approaches are possible for describing the linear optics; here, we propose an approach and notation that naturally generalizes the familiar Twiss parameters to the coupled case in three degrees of freedom. Our approach is based on an eigensystem analysis of the matrix of second-order beam moments, or alternatively (in the case of a storage ring) on an eigensystem analysis of the linear single-turn map. The lattice functions that emerge from this approach have an interpretation that is conceptually very simple: in particular, the lattice functions directly relate the beam distribution in phase space to the invariant emittances. To emphasize the physical significance of the coupled lattice functions, we develop the theory from first principles, using only the assumption of linear symplectic transport. We also give some examples of the application of this approach, demonstrating its advantages of conceptual and notational simplicity.

  14. Permutation inference for the general linear model

    PubMed Central

    Winkler, Anderson M.; Ridgway, Gerard R.; Webster, Matthew A.; Smith, Stephen M.; Nichols, Thomas E.

    2014-01-01

    Permutation methods can provide exact control of false positives and allow the use of non-standard statistics, making only weak assumptions about the data. With the availability of fast and inexpensive computing, their main limitation would be some lack of flexibility to work with arbitrary experimental designs. In this paper we report on results on approximate permutation methods that are more flexible with respect to the experimental design and nuisance variables, and conduct detailed simulations to identify the best method for settings that are typical for imaging research scenarios. We present a generic framework for permutation inference for complex general linear models (glms) when the errors are exchangeable and/or have a symmetric distribution, and show that, even in the presence of nuisance effects, these permutation inferences are powerful while providing excellent control of false positives in a wide range of common and relevant imaging research scenarios. We also demonstrate how the inference on glm parameters, originally intended for independent data, can be used in certain special but useful cases in which independence is violated. Detailed examples of common neuroimaging applications are provided, as well as a complete algorithm – the “randomise” algorithm – for permutation inference with the glm. PMID:24530839

  15. Evaluating the double Poisson generalized linear model.

    PubMed

    Zou, Yaotian; Geedipally, Srinivas Reddy; Lord, Dominique

    2013-10-01

    The objectives of this study are to: (1) examine the applicability of the double Poisson (DP) generalized linear model (GLM) for analyzing motor vehicle crash data characterized by over- and under-dispersion and (2) compare the performance of the DP GLM with the Conway-Maxwell-Poisson (COM-Poisson) GLM in terms of goodness-of-fit and theoretical soundness. The DP distribution has seldom been investigated and applied since its first introduction two decades ago. The hurdle for applying the DP is related to its normalizing constant (or multiplicative constant) which is not available in closed form. This study proposed a new method to approximate the normalizing constant of the DP with high accuracy and reliability. The DP GLM and COM-Poisson GLM were developed using two observed over-dispersed datasets and one observed under-dispersed dataset. The modeling results indicate that the DP GLM with its normalizing constant approximated by the new method can handle crash data characterized by over- and under-dispersion. Its performance is comparable to the COM-Poisson GLM in terms of goodness-of-fit (GOF), although COM-Poisson GLM provides a slightly better fit. For the over-dispersed data, the DP GLM performs similar to the NB GLM. Considering the fact that the DP GLM can be easily estimated with inexpensive computation and that it is simpler to interpret coefficients, it offers a flexible and efficient alternative for researchers to model count data.

  16. Symmetry Groups for Linear Programming Relaxations of Orthogonal Array Problems

    DTIC Science & Technology

    2015-03-26

    Symmetry Groups for Linear Programming Relaxations of Orthogonal Array Problems THESIS MARCH 2015 David M. Arquette, Second Lieutenant, USAF AFIT-ENC...work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENC-MS-15-M-003 SYMMETRY GROUPS FOR LINEAR...PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENC-MS-15-M-003 SYMMETRY GROUPS FOR LINEAR PROGRAMMING RELAXATIONS OF ORTHOGONAL ARRAY PROBLEMS David M

  17. Hybrid approximate message passing for generalized group sparsity

    NASA Astrophysics Data System (ADS)

    Fletcher, Alyson K.; Rangan, Sundeep

    2013-09-01

    We consider the problem of estimating a group sparse vector x ∈ Rn under a generalized linear measurement model. Group sparsity of x means the activity of different components of the vector occurs in groups - a feature common in estimation problems in image processing, simultaneous sparse approximation and feature selection with grouped variables. Unfortunately, many current group sparse estimation methods require that the groups are non-overlapping. This work considers problems with what we call generalized group sparsity where the activity of the different components of x are modeled as functions of a small number of boolean latent variables. We show that this model can incorporate a large class of overlapping group sparse problems including problems in sparse multivariable polynomial regression and gene expression analysis. To estimate vectors with such group sparse structures, the paper proposes to use a recently-developed hybrid generalized approximate message passing (HyGAMP) method. Approximate message passing (AMP) refers to a class of algorithms based on Gaussian and quadratic approximations of loopy belief propagation for estimation of random vectors under linear measurements. The HyGAMP method extends the AMP framework to incorporate priors on x described by graphical models of which generalized group sparsity is a special case. We show that the HyGAMP algorithm is computationally efficient, general and offers superior performance in certain synthetic data test cases.

  18. Centering, Scale Indeterminacy, and Differential Item Functioning Detection in Hierarchical Generalized Linear and Generalized Linear Mixed Models

    ERIC Educational Resources Information Center

    Cheong, Yuk Fai; Kamata, Akihito

    2013-01-01

    In this article, we discuss and illustrate two centering and anchoring options available in differential item functioning (DIF) detection studies based on the hierarchical generalized linear and generalized linear mixed modeling frameworks. We compared and contrasted the assumptions of the two options, and examined the properties of their DIF…

  19. Linear mixed-effects modeling approach to FMRI group analysis

    PubMed Central

    Chen, Gang; Saad, Ziad S.; Britton, Jennifer C.; Pine, Daniel S.; Cox, Robert W.

    2013-01-01

    Conventional group analysis is usually performed with Student-type t-test, regression, or standard AN(C)OVA in which the variance–covariance matrix is presumed to have a simple structure. Some correction approaches are adopted when assumptions about the covariance structure is violated. However, as experiments are designed with different degrees of sophistication, these traditional methods can become cumbersome, or even be unable to handle the situation at hand. For example, most current FMRI software packages have difficulty analyzing the following scenarios at group level: (1) taking within-subject variability into account when there are effect estimates from multiple runs or sessions; (2) continuous explanatory variables (covariates) modeling in the presence of a within-subject (repeated measures) factor, multiple subject-grouping (between-subjects) factors, or the mixture of both; (3) subject-specific adjustments in covariate modeling; (4) group analysis with estimation of hemodynamic response (HDR) function by multiple basis functions; (5) various cases of missing data in longitudinal studies; and (6) group studies involving family members or twins. Here we present a linear mixed-effects modeling (LME) methodology that extends the conventional group analysis approach to analyze many complicated cases, including the six prototypes delineated above, whose analyses would be otherwise either difficult or unfeasible under traditional frameworks such as AN(C)OVA and general linear model (GLM). In addition, the strength of the LME framework lies in its flexibility to model and estimate the variance–covariance structures for both random effects and residuals. The intraclass correlation (ICC) values can be easily obtained with an LME model with crossed random effects, even at the presence of confounding fixed effects. The simulations of one prototypical scenario indicate that the LME modeling keeps a balance between the control for false positives and the

  20. Generalized Weyl-Heisenberg (GWH) groups

    NASA Astrophysics Data System (ADS)

    Ghaani Farashahi, Arash

    2014-09-01

    Let be a locally compact group, be a locally compact Abelian (LCA) group, be a continuous homomorphism, and let be the semi-direct product of and with respect to the continuous homomorphism . In this article, we introduce the Generalized Weyl-Heisenberg (GWH) group associate with the semi-direct product group . We will study basic properties of from harmonic analysis aspects. Finally, we will illustrate applications of these methods in the case of some well-known semi-direct product groups.

  1. From linear to generalized linear mixed models: A case study in repeated measures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Compared to traditional linear mixed models, generalized linear mixed models (GLMMs) can offer better correspondence between response variables and explanatory models, yielding more efficient estimates and tests in the analysis of data from designed experiments. Using proportion data from a designed...

  2. Generalized perceptual linear prediction features for animal vocalization analysis.

    PubMed

    Clemins, Patrick J; Johnson, Michael T

    2006-07-01

    A new feature extraction model, generalized perceptual linear prediction (gPLP), is developed to calculate a set of perceptually relevant features for digital signal analysis of animal vocalizations. The gPLP model is a generalized adaptation of the perceptual linear prediction model, popular in human speech processing, which incorporates perceptual information such as frequency warping and equal loudness normalization into the feature extraction process. Since such perceptual information is available for a number of animal species, this new approach integrates that information into a generalized model to extract perceptually relevant features for a particular species. To illustrate, qualitative and quantitative comparisons are made between the species-specific model, generalized perceptual linear prediction (gPLP), and the original PLP model using a set of vocalizations collected from captive African elephants (Loxodonta africana) and wild beluga whales (Delphinapterus leucas). The models that incorporate perceptional information outperform the original human-based models in both visualization and classification tasks.

  3. A general non-linear multilevel structural equation mixture model

    PubMed Central

    Kelava, Augustin; Brandt, Holger

    2014-01-01

    In the past 2 decades latent variable modeling has become a standard tool in the social sciences. In the same time period, traditional linear structural equation models have been extended to include non-linear interaction and quadratic effects (e.g., Klein and Moosbrugger, 2000), and multilevel modeling (Rabe-Hesketh et al., 2004). We present a general non-linear multilevel structural equation mixture model (GNM-SEMM) that combines recent semiparametric non-linear structural equation models (Kelava and Nagengast, 2012; Kelava et al., 2014) with multilevel structural equation mixture models (Muthén and Asparouhov, 2009) for clustered and non-normally distributed data. The proposed approach allows for semiparametric relationships at the within and at the between levels. We present examples from the educational science to illustrate different submodels from the general framework. PMID:25101022

  4. Generalized Linear Multi-Frequency Imaging in VLBI

    NASA Astrophysics Data System (ADS)

    Likhachev, S.; Ladygin, V.; Guirin, I.

    2004-07-01

    In VLBI, generalized Linear Multi-Frequency Imaging (MFI) consists of multi-frequency synthesis (MFS) and multi-frequency analysis (MFA) of the VLBI data obtained from observations on various frequencies. A set of linear deconvolution MFI algorithms is described. The algorithms make it possible to obtain high quality images interpolated on any given frequency inside any given bandwidth, and to derive reliable estimates of spectral indexes for radio sources with continuum spectrum.

  5. Linear equations in general purpose codes for stiff ODEs

    SciTech Connect

    Shampine, L. F.

    1980-02-01

    It is noted that it is possible to improve significantly the handling of linear problems in a general-purpose code with very little trouble to the user or change to the code. In such situations analytical evaluation of the Jacobian is a lot cheaper than numerical differencing. A slight change in the point at which the Jacobian is evaluated results in a more accurate Jacobian in linear problems. (RWR)

  6. Uncertainty relations, zero point energy and the linear canonical group

    NASA Technical Reports Server (NTRS)

    Sudarshan, E. C. G.

    1993-01-01

    The close relationship between the zero point energy, the uncertainty relations, coherent states, squeezed states, and correlated states for one mode is investigated. This group-theoretic perspective enables the parametrization and identification of their multimode generalization. In particular the generalized Schroedinger-Robertson uncertainty relations are analyzed. An elementary method of determining the canonical structure of the generalized correlated states is presented.

  7. A Matrix Approach for General Higher Order Linear Recurrences

    DTIC Science & Technology

    2011-01-01

    properties of linear recurrences (such as the well-known Fibonacci and Pell sequences ). In [2], Er defined k linear recurring sequences of order at...the nth term of the ith generalized order-k Fibonacci sequence . Communicated by Lee See Keong. Received: March 26, 2009; Revised: August 28, 2009...6], the author gave the generalized order-k Fibonacci and Pell (F-P) sequence as follows: For m ≥ 0, n > 0 and 1 ≤ i ≤ k uin = 2 muin−1 + u i n−2

  8. Solution of generalized shifted linear systems with complex symmetric matrices

    NASA Astrophysics Data System (ADS)

    Sogabe, Tomohiro; Hoshi, Takeo; Zhang, Shao-Liang; Fujiwara, Takeo

    2012-07-01

    We develop the shifted COCG method [R. Takayama, T. Hoshi, T. Sogabe, S.-L. Zhang, T. Fujiwara, Linear algebraic calculation of Green's function for large-scale electronic structure theory, Phys. Rev. B 73 (165108) (2006) 1-9] and the shifted WQMR method [T. Sogabe, T. Hoshi, S.-L. Zhang, T. Fujiwara, On a weighted quasi-residual minimization strategy of the QMR method for solving complex symmetric shifted linear systems, Electron. Trans. Numer. Anal. 31 (2008) 126-140] for solving generalized shifted linear systems with complex symmetric matrices that arise from the electronic structure theory. The complex symmetric Lanczos process with a suitable bilinear form plays an important role in the development of the methods. The numerical examples indicate that the methods are highly attractive when the inner linear systems can efficiently be solved.

  9. Beam envelope calculations in general linear coupled lattices

    SciTech Connect

    Chung, Moses; Qin, Hong; Groening, Lars; Xiao, Chen; Davidson, Ronald C.

    2015-01-15

    The envelope equations and Twiss parameters (β and α) provide important bases for uncoupled linear beam dynamics. For sophisticated beam manipulations, however, coupling elements between two transverse planes are intentionally introduced. The recently developed generalized Courant-Snyder theory offers an effective way of describing the linear beam dynamics in such coupled systems with a remarkably similar mathematical structure to the original Courant-Snyder theory. In this work, we present numerical solutions to the symmetrized matrix envelope equation for β which removes the gauge freedom in the matrix envelope equation for w. Furthermore, we construct the transfer and beam matrices in terms of the generalized Twiss parameters, which enables calculation of the beam envelopes in arbitrary linear coupled systems.

  10. Linkage Group Xix of Chlamydomonas Reinhardtii Has a Linear Map

    PubMed Central

    Holmes, J. A.; Johnson, D. E.; Dutcher, S. K.

    1993-01-01

    Linkage group XIX (or the UNI linkage group) of Chlamydomonas reinhardtii has been reported to show a circular meiotic recombination map. A circular map predicts the existence of strong chiasma and chromatid interference, which would lead to an excess number of two-strand double crossovers during meiosis. We have tested this prediction in multipoint crosses. Our results are consistent with a linear linkage group that shows positive chiasma interference and no chromatid interference. Chiasma interference occurs both within arms and across the centromere. Of the original loci that contributed to the circular map, we find that two map to other linkage groups and a third cannot be retested because the mutant strain that defined it has been lost. A second reported unusual property for linkage group XIX was the increase in meiotic recombination with increases in temperature during a period that precedes the onset of meiosis. Although we observed changes in recombination frequencies in some intervals on linkage group XIX in crosses to CC-1952, and in strains heterozygous for the mutation ger1 at 16°, we also show that our strains do not exhibit the previously observed patterns of temperature-sensitive recombination for two different pairs of loci on linkage group XIX. We conclude that linkage group XIX has a linear genetic map that is not significantly different from other Chlamydomonas linkage groups. PMID:8462847

  11. Confidence Intervals for Assessing Heterogeneity in Generalized Linear Mixed Models

    ERIC Educational Resources Information Center

    Wagler, Amy E.

    2014-01-01

    Generalized linear mixed models are frequently applied to data with clustered categorical outcomes. The effect of clustering on the response is often difficult to practically assess partly because it is reported on a scale on which comparisons with regression parameters are difficult to make. This article proposes confidence intervals for…

  12. Testing non-linearity and directedness of interactions between neural groups in the macaque inferotemporal cortex.

    PubMed

    Freiwald, W A; Valdes, P; Bosch, J; Biscay, R; Jimenez, J C; Rodriguez, L M; Rodriguez, V; Kreiter, A K; Singer, W

    1999-12-15

    Information processing in the visual cortex depends on complex and context sensitive patterns of interactions between neuronal groups in many different cortical areas. Methods used to date for disentangling this functional connectivity presuppose either linearity or instantaneous interactions, assumptions that are not necessarily valid. In this paper a general framework that encompasses both linear and non-linear modelling of neurophysiological time series data by means of Local Linear Non-linear Autoregressive models (LLNAR) is described. Within this framework a new test for non-linearity of time series and for non-linearity of directedness of neural interactions based on LLNAR is presented. These tests assess the relative goodness of fit of linear versus non-linear models via the bootstrap technique. Additionally, a generalised definition of Granger causality is presented based on LLNAR that is valid for both linear and non-linear systems. Finally, the use of LLNAR for measuring non-linearity and directional influences is illustrated using artificial data, reference data as well as local field potentials (LFPs) from macaque area TE. LFP data is well described by the linear variant of LLNAR. Models of this sort, including lagged values of the preceding 25 to 60 ms, revealed the existence of both uni- and bi-directional influences between recording sites.

  13. The Linear Algebra Curriculum Study Group Recommendations for the First Course in Linear Algebra.

    ERIC Educational Resources Information Center

    Carlson, David; And Others

    1993-01-01

    Presents five recommendations of the Linear Algebra Curriculum Study Group: (1) The syllabus must respond to the client disciplines; (2) The first course should be matrix oriented; (3) Faculty should consider the needs and interests of students; (4) Faculty should use technology; and (5) At least one follow-up course should be required. Provides a…

  14. Generalized linear mixed models for meta-analysis.

    PubMed

    Platt, R W; Leroux, B G; Breslow, N

    1999-03-30

    We examine two strategies for meta-analysis of a series of 2 x 2 tables with the odds ratio modelled as a linear combination of study level covariates and random effects representing between-study variation. Penalized quasi-likelihood (PQL), an approximate inference technique for generalized linear mixed models, and a linear model fitted by weighted least squares to the observed log-odds ratios are used to estimate regression coefficients and dispersion parameters. Simulation results demonstrate that both methods perform adequate approximate inference under many conditions, but that neither method works well in the presence of highly sparse data. Under certain conditions with small cell frequencies the PQL method provides better inference.

  15. Credibility analysis of risk classes by generalized linear model

    NASA Astrophysics Data System (ADS)

    Erdemir, Ovgucan Karadag; Sucu, Meral

    2016-06-01

    In this paper generalized linear model (GLM) and credibility theory which are frequently used in nonlife insurance pricing are combined for reliability analysis. Using full credibility standard, GLM is associated with limited fluctuation credibility approach. Comparison criteria such as asymptotic variance and credibility probability are used to analyze the credibility of risk classes. An application is performed by using one-year claim frequency data of a Turkish insurance company and results of credible risk classes are interpreted.

  16. A general theory of linear cosmological perturbations: bimetric theories

    NASA Astrophysics Data System (ADS)

    Lagos, Macarena; Ferreira, Pedro G.

    2017-01-01

    We implement the method developed in [1] to construct the most general parametrised action for linear cosmological perturbations of bimetric theories of gravity. Specifically, we consider perturbations around a homogeneous and isotropic background, and identify the complete form of the action invariant under diffeomorphism transformations, as well as the number of free parameters characterising this cosmological class of theories. We discuss, in detail, the case without derivative interactions, and compare our results with those found in massive bigravity.

  17. Residuals analysis of the generalized linear models for longitudinal data.

    PubMed

    Chang, Y C

    2000-05-30

    The generalized estimation equation (GEE) method, one of the generalized linear models for longitudinal data, has been used widely in medical research. However, the related sensitivity analysis problem has not been explored intensively. One of the possible reasons for this was due to the correlated structure within the same subject. We showed that the conventional residuals plots for model diagnosis in longitudinal data could mislead a researcher into trusting the fitted model. A non-parametric method, named the Wald-Wolfowitz run test, was proposed to check the residuals plots both quantitatively and graphically. The rationale proposedin this paper is well illustrated with two real clinical studies in Taiwan.

  18. Linear spin-2 fields in most general backgrounds

    NASA Astrophysics Data System (ADS)

    Bernard, Laura; Deffayet, Cédric; Schmidt-May, Angnis; von Strauss, Mikael

    2016-04-01

    We derive the full perturbative equations of motion for the most general background solutions in ghost-free bimetric theory in its metric formulation. Clever field redefinitions at the level of fluctuations enable us to circumvent the problem of varying a square-root matrix appearing in the theory. This greatly simplifies the expressions for the linear variation of the bimetric interaction terms. We show that these field redefinitions exist and are uniquely invertible if and only if the variation of the square-root matrix itself has a unique solution, which is a requirement for the linearized theory to be well defined. As an application of our results we examine the constraint structure of ghost-free bimetric theory at the level of linear equations of motion for the first time. We identify a scalar combination of equations which is responsible for the absence of the Boulware-Deser ghost mode in the theory. The bimetric scalar constraint is in general not manifestly covariant in its nature. However, in the massive gravity limit the constraint assumes a covariant form when one of the interaction parameters is set to zero. For that case our analysis provides an alternative and almost trivial proof of the absence of the Boulware-Deser ghost. Our findings generalize previous results in the metric formulation of massive gravity and also agree with studies of its vielbein version.

  19. Linearized pseudo-Einstein equations on the Heisenberg group

    NASA Astrophysics Data System (ADS)

    Barletta, Elisabetta; Dragomir, Sorin; Jacobowitz, Howard

    2017-02-01

    We study the pseudo-Einstein equation R11bar = 0 on the Heisenberg group H1 = C × R. We consider first order perturbations θɛ =θ0 + ɛ θ and linearize the pseudo-Einstein equation about θ0 (the canonical Tanaka-Webster flat contact form on H1 thought of as a strictly pseudoconvex CR manifold). If θ =e2uθ0 the linearized pseudo-Einstein equation is Δb u - 4 | Lu|2 = 0 where Δb is the sublaplacian of (H1 ,θ0) and L bar is the Lewy operator. We solve the linearized pseudo-Einstein equation on a bounded domain Ω ⊂H1 by applying subelliptic theory i.e. existence and regularity results for weak subelliptic harmonic maps. We determine a solution u to the linearized pseudo-Einstein equation, possessing Heisenberg spherical symmetry, and such that u(x) → - ∞ as | x | → + ∞.

  20. General covariance from the quantum renormalization group

    NASA Astrophysics Data System (ADS)

    Shyam, Vasudev

    2017-03-01

    The quantum renormalization group (QRG) is a realization of holography through a coarse-graining prescription that maps the beta functions of a quantum field theory thought to live on the "boundary" of some space to holographic actions in the "bulk" of this space. A consistency condition will be proposed that translates into general covariance of the gravitational theory in the D +1 dimensional bulk. This emerges from the application of the QRG on a planar matrix field theory living on the D dimensional boundary. This will be a particular form of the Wess-Zumino consistency condition that the generating functional of the boundary theory needs to satisfy. In the bulk, this condition forces the Poisson bracket algebra of the scalar and vector constraints of the dual gravitational theory to close in a very specific manner, namely, the manner in which the corresponding constraints of general relativity do. A number of features of the gravitational theory will be fixed as a consequence of this form of the Poisson bracket algebra. In particular, it will require the metric beta function to be of the gradient form.

  1. Linear and nonlinear propagation of water wave groups

    NASA Technical Reports Server (NTRS)

    Pierson, W. J., Jr.; Donelan, M. A.; Hui, W. H.

    1992-01-01

    Results are presented from a study of the evolution of waveforms with known analytical group shapes, in the form of both transient wave groups and the cloidal (cn) and dnoidal (dn) wave trains as derived from the nonlinear Schroedinger equation. The waveforms were generated in a long wind-wave tank of the Canada Centre for Inland Waters. It was found that the low-amplitude transients behaved as predicted by the linear theory and that the cn and dn wave trains of moderate steepness behaved almost as predicted by the nonlinear Schroedinger equation. Some of the results did not fit into any of the available theories for waves on water, but they provide important insight on how actual groups of waves propagate and on higher-order effects for a transient waveform.

  2. Comparative Study of Algorithms for Automated Generalization of Linear Objects

    NASA Astrophysics Data System (ADS)

    Azimjon, S.; Gupta, P. K.; Sukhmani, R. S. G. S.

    2014-11-01

    Automated generalization, rooted from conventional cartography, has become an increasing concern in both geographic information system (GIS) and mapping fields. All geographic phenomenon and the processes are bound to the scale, as it is impossible for human being to observe the Earth and the processes in it without decreasing its scale. To get optimal results, cartographers and map-making agencies develop set of rules and constraints, however these rules are under consideration and topic for many researches up until recent days. Reducing map generating time and giving objectivity is possible by developing automated map generalization algorithms (McMaster and Shea, 1988). Modification of the scale traditionally is a manual process, which requires knowledge of the expert cartographer, and it depends on the experience of the user, which makes the process very subjective as every user may generate different map with same requirements. However, automating generalization based on the cartographic rules and constrains can give consistent result. Also, developing automated system for map generation is the demand of this rapid changing world. The research that we have conveyed considers only generalization of the roads, as it is one of the indispensable parts of a map. Dehradun city, Uttarakhand state of India was selected as a study area. The study carried out comparative study of the generalization software sets, operations and algorithms available currently, also considers advantages and drawbacks of the existing software used worldwide. Research concludes with the development of road network generalization tool and with the final generalized road map of the study area, which explores the use of open source python programming language and attempts to compare different road network generalization algorithms. Thus, the paper discusses the alternative solutions for automated generalization of linear objects using GIS-technologies. Research made on automated of road network

  3. Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Gottwald, Fabian; Karsten, Sven; Ivanov, Sergei D.; Kühn, Oliver

    2015-06-01

    Fundamental understanding of complex dynamics in many-particle systems on the atomistic level is of utmost importance. Often the systems of interest are of macroscopic size but can be partitioned into a few important degrees of freedom which are treated most accurately and others which constitute a thermal bath. Particular attention in this respect attracts the linear generalized Langevin equation, which can be rigorously derived by means of a linear projection technique. Within this framework, a complicated interaction with the bath can be reduced to a single memory kernel. This memory kernel in turn is parametrized for a particular system studied, usually by means of time-domain methods based on explicit molecular dynamics data. Here, we discuss that this task is more naturally achieved in frequency domain and develop a Fourier-based parametrization method that outperforms its time-domain analogues. Very surprisingly, the widely used rigid bond method turns out to be inappropriate in general. Importantly, we show that the rigid bond approach leads to a systematic overestimation of relaxation times, unless the system under study consists of a harmonic bath bi-linearly coupled to the relevant degrees of freedom.

  4. Extracting Embedded Generalized Networks from Linear Programming Problems.

    DTIC Science & Technology

    1984-09-01

    E EXTRACTING EMBEDDED GENERALIZED NETWORKS FROM LINEAR PROGRAMMING PROBLEMS by Gerald G. Brown * . ___Richard D. McBride * R. Kevin Wood LcL7...authorized. EA Gerald ’Brown Richar-rD. McBride 46;val Postgrduate School University of Southern California Monterey, California 93943 Los Angeles...REOT UBE . OV S.SF- PERFOING’ CAORG soN UER. 7. AUTNOR(a) S. CONTRACT ON GRANT NUME111() Gerald G. Brown Richard D. McBride S. PERFORMING ORGANIZATION

  5. Generalization of continuous-variable quantum cloning with linear optics

    SciTech Connect

    Zhai Zehui; Guo Juan; Gao Jiangrui

    2006-05-15

    We propose an asymmetric quantum cloning scheme. Based on the proposal and experiment by Andersen et al. [Phys. Rev. Lett. 94, 240503 (2005)], we generalize it to two asymmetric cases: quantum cloning with asymmetry between output clones and between quadrature variables. These optical implementations also employ linear elements and homodyne detection only. Finally, we also compare the utility of symmetric and asymmetric cloning in an analysis of a squeezed-state quantum key distribution protocol and find that the asymmetric one is more advantageous.

  6. Evolutionary dynamics of general group interactions in structured populations

    NASA Astrophysics Data System (ADS)

    Li, Aming; Broom, Mark; Du, Jinming; Wang, Long

    2016-02-01

    The evolution of populations is influenced by many factors, and the simple classical models have been developed in a number of important ways. Both population structure and multiplayer interactions have been shown to significantly affect the evolution of important properties, such as the level of cooperation or of aggressive behavior. Here we combine these two key factors and develop the evolutionary dynamics of general group interactions in structured populations represented by regular graphs. The traditional linear and threshold public goods games are adopted as models to address the dynamics. We show that for linear group interactions, population structure can favor the evolution of cooperation compared to the well-mixed case, and we see that the more neighbors there are, the harder it is for cooperators to persist in structured populations. We further show that threshold group interactions could lead to the emergence of cooperation even in well-mixed populations. Here population structure sometimes inhibits cooperation for the threshold public goods game, where depending on the benefit to cost ratio, the outcomes are bistability or a monomorphic population of defectors or cooperators. Our results suggest, counterintuitively, that structured populations are not always beneficial for the evolution of cooperation for nonlinear group interactions.

  7. Generalized space and linear momentum operators in quantum mechanics

    SciTech Connect

    Costa, Bruno G. da

    2014-06-15

    We propose a modification of a recently introduced generalized translation operator, by including a q-exponential factor, which implies in the definition of a Hermitian deformed linear momentum operator p{sup ^}{sub q}, and its canonically conjugate deformed position operator x{sup ^}{sub q}. A canonical transformation leads the Hamiltonian of a position-dependent mass particle to another Hamiltonian of a particle with constant mass in a conservative force field of a deformed phase space. The equation of motion for the classical phase space may be expressed in terms of the generalized dual q-derivative. A position-dependent mass confined in an infinite square potential well is shown as an instance. Uncertainty and correspondence principles are analyzed.

  8. General quantum constraints on detector noise in continuous linear measurements

    NASA Astrophysics Data System (ADS)

    Miao, Haixing

    2017-01-01

    In quantum sensing and metrology, an important class of measurement is the continuous linear measurement, in which the detector is coupled to the system of interest linearly and continuously in time. One key aspect involved is the quantum noise of the detector, arising from quantum fluctuations in the detector input and output. It determines how fast we acquire information about the system and also influences the system evolution in terms of measurement backaction. We therefore often categorize it as the so-called imprecision noise and quantum backaction noise. There is a general Heisenberg-like uncertainty relation that constrains the magnitude of and the correlation between these two types of quantum noise. The main result of this paper is to show that, when the detector becomes ideal, i.e., at the quantum limit with minimum uncertainty, not only does the uncertainty relation takes the equal sign as expected, but also there are two new equalities. This general result is illustrated by using the typical cavity QED setup with the system being either a qubit or a mechanical oscillator. Particularly, the dispersive readout of a qubit state, and the measurement of mechanical motional sideband asymmetry are considered.

  9. Generalized linear mixed model for segregation distortion analysis

    PubMed Central

    2011-01-01

    Background Segregation distortion is a phenomenon that the observed genotypic frequencies of a locus fall outside the expected Mendelian segregation ratio. The main cause of segregation distortion is viability selection on linked marker loci. These viability selection loci can be mapped using genome-wide marker information. Results We developed a generalized linear mixed model (GLMM) under the liability model to jointly map all viability selection loci of the genome. Using a hierarchical generalized linear mixed model, we can handle the number of loci several times larger than the sample size. We used a dataset from an F2 mouse family derived from the cross of two inbred lines to test the model and detected a major segregation distortion locus contributing 75% of the variance of the underlying liability. Replicated simulation experiments confirm that the power of viability locus detection is high and the false positive rate is low. Conclusions Not only can the method be used to detect segregation distortion loci, but also used for mapping quantitative trait loci of disease traits using case only data in humans and selected populations in plants and animals. PMID:22078575

  10. Multivariate sparse group lasso for the multivariate multiple linear regression with an arbitrary group structure

    PubMed Central

    Li, Yanming; Zhu, Ji

    2015-01-01

    Summary We propose a multivariate sparse group lasso variable selection and estimation method for data with high-dimensional predictors as well as high-dimensional response variables. The method is carried out through a penalized multivariate multiple linear regression model with an arbitrary group structure for the regression coefficient matrix. It suits many biology studies well in detecting associations between multiple traits and multiple predictors, with each trait and each predictor embedded in some biological functioning groups such as genes, pathways or brain regions. The method is able to effectively remove unimportant groups as well as unimportant individual coefficients within important groups, particularly for large p small n problems, and is flexible in handling various complex group structures such as overlapping or nested or multilevel hierarchical structures. The method is evaluated through extensive simulations with comparisons to the conventional lasso and group lasso methods, and is applied to an eQTL association study. PMID:25732839

  11. A new family of gauges in linearized general relativity

    NASA Astrophysics Data System (ADS)

    Esposito, Giampiero; Stornaiolo, Cosimo

    2000-05-01

    For vacuum Maxwell theory in four dimensions, a supplementary condition exists (due to Eastwood and Singer) which is invariant under conformal rescalings of the metric, in agreement with the conformal symmetry of the Maxwell equations. Thus, starting from the de Donder gauge, which is not conformally invariant but is the gravitational counterpart of the Lorenz gauge, one can consider, led by formal analogy, a new family of gauges in general relativity, which involve fifth-order covariant derivatives of metric perturbations. The admissibility of such gauges in the classical theory is first proven in the cases of linearized theory about flat Euclidean space or flat Minkowski spacetime. In the former, the general solution of the equation for the fulfillment of the gauge condition after infinitesimal diffeomorphisms involves a 3-harmonic 1-form and an inverse Fourier transform. In the latter, one needs instead the kernel of powers of the wave operator, and a contour integral. The analysis is also used to put restrictions on the dimensionless parameter occurring in the DeWitt supermetric, while the proof of admissibility is generalized to a suitable class of curved Riemannian backgrounds. Eventually, a non-local construction of the tensor field is obtained which makes it possible to achieve conformal invariance of the above gauges.

  12. Optimization in generalized linear models: A case study

    NASA Astrophysics Data System (ADS)

    Silva, Eliana Costa e.; Correia, Aldina; Lopes, Isabel Cristina

    2016-06-01

    The maximum likelihood method is usually chosen to estimate the regression parameters of Generalized Linear Models (GLM) and also for hypothesis testing and goodness of fit tests. The classical method for estimating GLM parameters is the Fisher scores. In this work we propose to compute the estimates of the parameters with two alternative methods: a derivative-based optimization method, namely the BFGS method which is one of the most popular of the quasi-Newton algorithms, and the PSwarm derivative-free optimization method that combines features of a pattern search optimization method with a global Particle Swarm scheme. As a case study we use a dataset of biological parameters (phytoplankton) and chemical and environmental parameters of the water column of a Portuguese reservoir. The results show that, for this dataset, BFGS and PSwarm methods provided a better fit, than Fisher scores method, and can be good alternatives for finding the estimates for the parameters of a GLM.

  13. Generalized t-statistic for two-group classification.

    PubMed

    Komori, Osamu; Eguchi, Shinto; Copas, John B

    2015-06-01

    In the classic discriminant model of two multivariate normal distributions with equal variance matrices, the linear discriminant function is optimal both in terms of the log likelihood ratio and in terms of maximizing the standardized difference (the t-statistic) between the means of the two distributions. In a typical case-control study, normality may be sensible for the control sample but heterogeneity and uncertainty in diagnosis may suggest that a more flexible model is needed for the cases. We generalize the t-statistic approach by finding the linear function which maximizes a standardized difference but with data from one of the groups (the cases) filtered by a possibly nonlinear function U. We study conditions for consistency of the method and find the function U which is optimal in the sense of asymptotic efficiency. Optimality may also extend to other measures of discriminatory efficiency such as the area under the receiver operating characteristic curve. The optimal function U depends on a scalar probability density function which can be estimated non-parametrically using a standard numerical algorithm. A lasso-like version for variable selection is implemented by adding L1-regularization to the generalized t-statistic. Two microarray data sets in the study of asthma and various cancers are used as motivating examples.

  14. Are There Optical Solitary Wave Solutions in Linear Media with Group Velocity Dispersion?

    NASA Technical Reports Server (NTRS)

    Li, Zhonghao; Zhou, Guosheng

    1996-01-01

    A generalized exact optical bright solitary wave solution in a three dimensional dispersive linear medium is presented. The most interesting property of the solution is that it can exist in the normal group-velocity-dispersion (GVD) region. In addition, another peculiar feature is that it may achieve a condition of 'zero-dispersion' to the media so that a solitary wave of arbitrarily small amplitude may be propagated with no dependence on is pulse width.

  15. Adaptive Error Estimation in Linearized Ocean General Circulation Models

    NASA Technical Reports Server (NTRS)

    Chechelnitsky, Michael Y.

    1999-01-01

    Data assimilation methods are routinely used in oceanography. The statistics of the model and measurement errors need to be specified a priori. This study addresses the problem of estimating model and measurement error statistics from observations. We start by testing innovation based methods of adaptive error estimation with low-dimensional models in the North Pacific (5-60 deg N, 132-252 deg E) to TOPEX/POSEIDON (TIP) sea level anomaly data, acoustic tomography data from the ATOC project, and the MIT General Circulation Model (GCM). A reduced state linear model that describes large scale internal (baroclinic) error dynamics is used. The methods are shown to be sensitive to the initial guess for the error statistics and the type of observations. A new off-line approach is developed, the covariance matching approach (CMA), where covariance matrices of model-data residuals are "matched" to their theoretical expectations using familiar least squares methods. This method uses observations directly instead of the innovations sequence and is shown to be related to the MT method and the method of Fu et al. (1993). Twin experiments using the same linearized MIT GCM suggest that altimetric data are ill-suited to the estimation of internal GCM errors, but that such estimates can in theory be obtained using acoustic data. The CMA is then applied to T/P sea level anomaly data and a linearization of a global GFDL GCM which uses two vertical modes. We show that the CMA method can be used with a global model and a global data set, and that the estimates of the error statistics are robust. We show that the fraction of the GCM-T/P residual variance explained by the model error is larger than that derived in Fukumori et al.(1999) with the method of Fu et al.(1993). Most of the model error is explained by the barotropic mode. However, we find that impact of the change in the error statistics on the data assimilation estimates is very small. This is explained by the large

  16. Process Setting through General Linear Model and Response Surface Method

    NASA Astrophysics Data System (ADS)

    Senjuntichai, Angsumalin

    2010-10-01

    The objective of this study is to improve the efficiency of the flow-wrap packaging process in soap industry through the reduction of defectives. At the 95% confidence level, with the regression analysis, the sealing temperature, temperatures of upper and lower crimper are found to be the significant factors for the flow-wrap process with respect to the number/percentage of defectives. Twenty seven experiments have been designed and performed according to three levels of each controllable factor. With the general linear model (GLM), the suggested values for the sealing temperature, temperatures of upper and lower crimpers are 185, 85 and 85° C, respectively while the response surface method (RSM) provides the optimal process conditions at 186, 89 and 88° C. Due to different assumptions between percentage of defective and all three temperature parameters, the suggested conditions from the two methods are then slightly different. Fortunately, the estimated percentage of defectives at 5.51% under GLM process condition and the predicted percentage of defectives at 4.62% under RSM process condition are not significant different. But at 95% confidence level, the percentage of defectives under RSM condition can be much lower approximately 2.16% than those under GLM condition in accordance with wider variation. Lastly, the percentages of defectives under the conditions suggested by GLM and RSM are reduced by 55.81% and 62.95%, respectively.

  17. A general approach to mixed effects modeling of residual variances in generalized linear mixed models

    PubMed Central

    Kizilkaya, Kadir; Tempelman, Robert J

    2005-01-01

    We propose a general Bayesian approach to heteroskedastic error modeling for generalized linear mixed models (GLMM) in which linked functions of conditional means and residual variances are specified as separate linear combinations of fixed and random effects. We focus on the linear mixed model (LMM) analysis of birth weight (BW) and the cumulative probit mixed model (CPMM) analysis of calving ease (CE). The deviance information criterion (DIC) was demonstrated to be useful in correctly choosing between homoskedastic and heteroskedastic error GLMM for both traits when data was generated according to a mixed model specification for both location parameters and residual variances. Heteroskedastic error LMM and CPMM were fitted, respectively, to BW and CE data on 8847 Italian Piemontese first parity dams in which residual variances were modeled as functions of fixed calf sex and random herd effects. The posterior mean residual variance for male calves was over 40% greater than that for female calves for both traits. Also, the posterior means of the standard deviation of the herd-specific variance ratios (relative to a unitary baseline) were estimated to be 0.60 ± 0.09 for BW and 0.74 ± 0.14 for CE. For both traits, the heteroskedastic error LMM and CPMM were chosen over their homoskedastic error counterparts based on DIC values. PMID:15588567

  18. A general protocol to afford enantioenriched linear homoprenylic amines.

    PubMed

    Bosque, Irene; Foubelo, Francisco; Gonzalez-Gomez, Jose C

    2013-11-21

    The reaction of a readily obtained chiral branched homoprenylamonium salt with a range of aldehydes, including aliphatic substrates, affords the corresponding linear isomers in good yields and enantioselectivities.

  19. Connections between Generalizing and Justifying: Students' Reasoning with Linear Relationships

    ERIC Educational Resources Information Center

    Ellis, Amy B.

    2007-01-01

    Research investigating algebra students' abilities to generalize and justify suggests that they experience difficulty in creating and using appropriate generalizations and proofs. Although the field has documented students' errors, less is known about what students do understand to be general and convincing. This study examines the ways in which…

  20. When are emotions related to group-based appraisals? A comparison between group-based emotions and general group emotions.

    PubMed

    Kuppens, Toon; Yzerbyt, Vincent Y

    2014-12-01

    In the literature on emotions in intergroup relations, it is not always clear how exactly emotions are group-related. Here, we distinguish between emotions that involve appraisals of immediate group concerns (i.e., group-based emotions) and emotions that do not. Recently, general group emotions, measured by asking people how they feel "as a group member" but without specifying an object for these emotions, have been conceptualized as reflecting appraisals of group concerns. In contrast, we propose that general group emotions are best seen as emotions about belonging to a group. In two studies, general group emotions were closely related to emotions that are explicitly measured as belonging emotions. Two further studies showed that general group emotions were not related to appraisals of immediate group concerns, whereas group-based emotions were. We argue for more specificity regarding the group-level aspects of emotion that are tapped by emotion measures.

  1. Generalizing a Categorization of Students' Interpretations of Linear Kinematics Graphs

    ERIC Educational Resources Information Center

    Bollen, Laurens; De Cock, Mieke; Zuza, Kristina; Guisasola, Jenaro; van Kampen, Paul

    2016-01-01

    We have investigated whether and how a categorization of responses to questions on linear distance-time graphs, based on a study of Irish students enrolled in an algebra-based course, could be adopted and adapted to responses from students enrolled in calculus-based physics courses at universities in Flanders, Belgium (KU Leuven) and the Basque…

  2. A General Linear Method for Equating with Small Samples

    ERIC Educational Resources Information Center

    Albano, Anthony D.

    2015-01-01

    Research on equating with small samples has shown that methods with stronger assumptions and fewer statistical estimates can lead to decreased error in the estimated equating function. This article introduces a new approach to linear observed-score equating, one which provides flexible control over how form difficulty is assumed versus estimated…

  3. On the Feasibility of a Generalized Linear Program

    DTIC Science & Technology

    1989-03-01

    generealized linear program by applying the same algorithm to a "phase-one" problem without requiring that the initial basic feasible solution to the latter be non-degenerate. secUrMTY C.AMlIS CAYI S OP ?- PAeES( UII -W & ,

  4. The general linear inverse problem - Implication of surface waves and free oscillations for earth structure.

    NASA Technical Reports Server (NTRS)

    Wiggins, R. A.

    1972-01-01

    The discrete general linear inverse problem reduces to a set of m equations in n unknowns. There is generally no unique solution, but we can find k linear combinations of parameters for which restraints are determined. The parameter combinations are given by the eigenvectors of the coefficient matrix. The number k is determined by the ratio of the standard deviations of the observations to the allowable standard deviations in the resulting solution. Various linear combinations of the eigenvectors can be used to determine parameter resolution and information distribution among the observations. Thus we can determine where information comes from among the observations and exactly how it constraints the set of possible models. The application of such analyses to surface-wave and free-oscillation observations indicates that (1) phase, group, and amplitude observations for any particular mode provide basically the same type of information about the model; (2) observations of overtones can enhance the resolution considerably; and (3) the degree of resolution has generally been overestimated for many model determinations made from surface waves.

  5. Generalized linear and generalized additive models in studies of species distributions: Setting the scene

    USGS Publications Warehouse

    Guisan, A.; Edwards, T.C.; Hastie, T.

    2002-01-01

    An important statistical development of the last 30 years has been the advance in regression analysis provided by generalized linear models (GLMs) and generalized additive models (GAMs). Here we introduce a series of papers prepared within the framework of an international workshop entitled: Advances in GLMs/GAMs modeling: from species distribution to environmental management, held in Riederalp, Switzerland, 6-11 August 2001. We first discuss some general uses of statistical models in ecology, as well as provide a short review of several key examples of the use of GLMs and GAMs in ecological modeling efforts. We next present an overview of GLMs and GAMs, and discuss some of their related statistics used for predictor selection, model diagnostics, and evaluation. Included is a discussion of several new approaches applicable to GLMs and GAMs, such as ridge regression, an alternative to stepwise selection of predictors, and methods for the identification of interactions by a combined use of regression trees and several other approaches. We close with an overview of the papers and how we feel they advance our understanding of their application to ecological modeling. ?? 2002 Elsevier Science B.V. All rights reserved.

  6. Role of group velocity in tracking field energy in linear dielectrics

    NASA Astrophysics Data System (ADS)

    Ware, Michael J.; Glasgow, S. A.; Peatross, Justin B.

    2001-11-01

    A new context for the group delay function (valid for pulses of arbitrary bandwidth) is presented for electromagnetic pulses propagating in a uniform linear dielectric medium. The traditional formulation of group velocity is recovered by taking a narrowband limit of this generalized context. The arrival time of a light pulse at a point in space is defined using a time expectation integral over the Poynting vector. The delay between pulse arrival times at two distinct points consists of two parts: a spectral superposition of group delays and a delay due to spectral reshaping via absorption or amplification. The use of the new context is illustrated for pulses propagating both superluminally and subluminally. The inevitable transition to subluminal behavior for any initially superluminal pulse is also demonstrated.

  7. Generalizing a categorization of students' interpretations of linear kinematics graphs

    NASA Astrophysics Data System (ADS)

    Bollen, Laurens; De Cock, Mieke; Zuza, Kristina; Guisasola, Jenaro; van Kampen, Paul

    2016-06-01

    We have investigated whether and how a categorization of responses to questions on linear distance-time graphs, based on a study of Irish students enrolled in an algebra-based course, could be adopted and adapted to responses from students enrolled in calculus-based physics courses at universities in Flanders, Belgium (KU Leuven) and the Basque Country, Spain (University of the Basque Country). We discuss how we adapted the categorization to accommodate a much more diverse student cohort and explain how the prior knowledge of students may account for many differences in the prevalence of approaches and success rates. Although calculus-based physics students make fewer mistakes than algebra-based physics students, they encounter similar difficulties that are often related to incorrectly dividing two coordinates. We verified that a qualitative understanding of kinematics is an important but not sufficient condition for students to determine a correct value for the speed. When comparing responses to questions on linear distance-time graphs with responses to isomorphic questions on linear water level versus time graphs, we observed that the context of a question influences the approach students use. Neither qualitative understanding nor an ability to find the slope of a context-free graph proved to be a reliable predictor for the approach students use when they determine the instantaneous speed.

  8. Linear polarization of a group of symbiotic systems

    NASA Astrophysics Data System (ADS)

    Brandi, E.; García, L. G.; Piirola, V.; Scaltriti, F.; Quiroga, C.

    2000-08-01

    We report linear polarization measurements of a set of symbiotic stars, made at several epochs during the period 1994-1998. Evidence of intrinsic polarization is looked for from the wavelength dependence of the polarization degree and position angle in UBVRI bands. The results have also been analysed to search for temporal variability of polarization. Several objects have shown a polarization spectrum different from that produced by interstellar dust grains and/or polarimetric variations on time scales as short as several days or months, indicating the presence of polarization component of circumstellar origin. Based on observations taken at Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación and the National Universities of La Plata, Córdoba and San Juan.

  9. Algebraic linearization of dynamics of Calogero type for any Coxeter group

    NASA Astrophysics Data System (ADS)

    Caseiro, R.; Françoise, J.-P.; Sasaki, R.

    2000-07-01

    Calogero-Moser systems can be generalized for any root system (including the noncrystallographic cases). The algebraic linearization of the generalized Calogero-Moser systems and of their quadratic (respectively quartic) perturbations are discussed.

  10. Commensurate Priors for Incorporating Historical Information in Clinical Trials Using General and Generalized Linear Models.

    PubMed

    Hobbs, Brian P; Sargent, Daniel J; Carlin, Bradley P

    2012-08-28

    Assessing between-study variability in the context of conventional random-effects meta-analysis is notoriously difficult when incorporating data from only a small number of historical studies. In order to borrow strength, historical and current data are often assumed to be fully homogeneous, but this can have drastic consequences for power and Type I error if the historical information is biased. In this paper, we propose empirical and fully Bayesian modifications of the commensurate prior model (Hobbs et al., 2011) extending Pocock (1976), and evaluate their frequentist and Bayesian properties for incorporating patient-level historical data using general and generalized linear mixed regression models. Our proposed commensurate prior models lead to preposterior admissible estimators that facilitate alternative bias-variance trade-offs than those offered by pre-existing methodologies for incorporating historical data from a small number of historical studies. We also provide a sample analysis of a colon cancer trial comparing time-to-disease progression using a Weibull regression model.

  11. Generalized linear IgA dermatosis with palmar involvement.

    PubMed

    Norris, Ivy N; Haeberle, M Tye; Callen, Jeffrey P; Malone, Janine C

    2015-09-17

    Linear IgA bullous dermatosis (LABD) is a sub-epidermal blistering disorder characterized by deposition of IgA along the basement membrane zone (BMZ) as detected by immunofluorescence microscopy. The diagnosis is made by clinicopathologic correlation with immunofluorescence confirmation. Differentiation from other bullous dermatoses is important because therapeutic measures differ. Prompt initiation of the appropriate therapies can have a major impact on outcomes. We present three cases with prominent palmar involvement to alert the clinician of this potential physical exam finding and to consider LABD in the right context.

  12. Transferability of regional permafrost disturbance susceptibility modelling using generalized linear and generalized additive models

    NASA Astrophysics Data System (ADS)

    Rudy, Ashley C. A.; Lamoureux, Scott F.; Treitz, Paul; van Ewijk, Karin Y.

    2016-07-01

    To effectively assess and mitigate risk of permafrost disturbance, disturbance-prone areas can be predicted through the application of susceptibility models. In this study we developed regional susceptibility models for permafrost disturbances using a field disturbance inventory to test the transferability of the model to a broader region in the Canadian High Arctic. Resulting maps of susceptibility were then used to explore the effect of terrain variables on the occurrence of disturbances within this region. To account for a large range of landscape characteristics, the model was calibrated using two locations: Sabine Peninsula, Melville Island, NU, and Fosheim Peninsula, Ellesmere Island, NU. Spatial patterns of disturbance were predicted with a generalized linear model (GLM) and generalized additive model (GAM), each calibrated using disturbed and randomized undisturbed locations from both locations and GIS-derived terrain predictor variables including slope, potential incoming solar radiation, wetness index, topographic position index, elevation, and distance to water. Each model was validated for the Sabine and Fosheim Peninsulas using independent data sets while the transferability of the model to an independent site was assessed at Cape Bounty, Melville Island, NU. The regional GLM and GAM validated well for both calibration sites (Sabine and Fosheim) with the area under the receiver operating curves (AUROC) > 0.79. Both models were applied directly to Cape Bounty without calibration and validated equally with AUROC's of 0.76; however, each model predicted disturbed and undisturbed samples differently. Additionally, the sensitivity of the transferred model was assessed using data sets with different sample sizes. Results indicated that models based on larger sample sizes transferred more consistently and captured the variability within the terrain attributes in the respective study areas. Terrain attributes associated with the initiation of disturbances were

  13. Item Purification in Differential Item Functioning Using Generalized Linear Mixed Models

    ERIC Educational Resources Information Center

    Liu, Qian

    2011-01-01

    For this dissertation, four item purification procedures were implemented onto the generalized linear mixed model for differential item functioning (DIF) analysis, and the performance of these item purification procedures was investigated through a series of simulations. Among the four procedures, forward and generalized linear mixed model (GLMM)…

  14. An Application of General System Theory (GST) to Group Therapy.

    ERIC Educational Resources Information Center

    Matthews, Charles O.

    1992-01-01

    Demonstrates the compatibility of General System Theory (GST) with the traditional counseling literature in explicating a therapy group's progression through Tuckman's (1965, 1977) developmental stages (forming, storming, norming, performing, and adjourning). Description uses both traditional group literature and GST concepts. (Author/NB)

  15. Computer analysis of general linear networks using digraphs.

    NASA Technical Reports Server (NTRS)

    Mcclenahan, J. O.; Chan, S.-P.

    1972-01-01

    Investigation of the application of digraphs in analyzing general electronic networks, and development of a computer program based on a particular digraph method developed by Chen. The Chen digraph method is a topological method for solution of networks and serves as a shortcut when hand calculations are required. The advantage offered by this method of analysis is that the results are in symbolic form. It is limited, however, by the size of network that may be handled. Usually hand calculations become too tedious for networks larger than about five nodes, depending on how many elements the network contains. Direct determinant expansion for a five-node network is a very tedious process also.

  16. Generalized geometry, T-duality, and renormalization group flow

    NASA Astrophysics Data System (ADS)

    Streets, Jeffrey

    2017-04-01

    We interpret the physical B-field renormalization group flow in the language of Courant algebroids, clarifying the sense in which this flow is the natural ;Ricci flow; for generalized geometry. Next we show that the B-field renormalization group flow preserves T-duality in a natural sense. As corollaries we obtain new long time existence results for the B-field renormalization group flow.

  17. Bayesian generalized linear mixed modeling of Tuberculosis using informative priors

    PubMed Central

    Woldegerima, Woldegebriel Assefa

    2017-01-01

    TB is rated as one of the world’s deadliest diseases and South Africa ranks 9th out of the 22 countries with hardest hit of TB. Although many pieces of research have been carried out on this subject, this paper steps further by inculcating past knowledge into the model, using Bayesian approach with informative prior. Bayesian statistics approach is getting popular in data analyses. But, most applications of Bayesian inference technique are limited to situations of non-informative prior, where there is no solid external information about the distribution of the parameter of interest. The main aim of this study is to profile people living with TB in South Africa. In this paper, identical regression models are fitted for classical and Bayesian approach both with non-informative and informative prior, using South Africa General Household Survey (GHS) data for the year 2014. For the Bayesian model with informative prior, South Africa General Household Survey dataset for the year 2011 to 2013 are used to set up priors for the model 2014. PMID:28257437

  18. Bayesian generalized linear mixed modeling of Tuberculosis using informative priors.

    PubMed

    Ojo, Oluwatobi Blessing; Lougue, Siaka; Woldegerima, Woldegebriel Assefa

    2017-01-01

    TB is rated as one of the world's deadliest diseases and South Africa ranks 9th out of the 22 countries with hardest hit of TB. Although many pieces of research have been carried out on this subject, this paper steps further by inculcating past knowledge into the model, using Bayesian approach with informative prior. Bayesian statistics approach is getting popular in data analyses. But, most applications of Bayesian inference technique are limited to situations of non-informative prior, where there is no solid external information about the distribution of the parameter of interest. The main aim of this study is to profile people living with TB in South Africa. In this paper, identical regression models are fitted for classical and Bayesian approach both with non-informative and informative prior, using South Africa General Household Survey (GHS) data for the year 2014. For the Bayesian model with informative prior, South Africa General Household Survey dataset for the year 2011 to 2013 are used to set up priors for the model 2014.

  19. Minimum deformations of commutative algebra and linear group GL(n)

    NASA Astrophysics Data System (ADS)

    Zupnik, B. M.

    1993-06-01

    In the algebra of formal series M q ( x i ), the relations of generalized commutativity that preserve the tensor I q grading and depend on parameters q(i, k) are considered. A norm of the differential calculus on M q consistent with the I q grading is chosen. A new construction of a symmetrized tensor product of algebras of the type M q ( x i ) and a corresponding definition of the minimally deformed linear group QGL(n) and Lie algebra qgl(n) are proposed. A study is made of the connection of QGL(n) and qgl(n) with the special matrix algebra Mat( n, Q), which consists of matrices with noncommuting elements. The deformed determinant in the algebra Mat( n, Q) is defined. The exponential mapping in the algebra Mat( n, Q) is considered on the basis of the Campbell-Hausdorff formula.

  20. Group classification of a generalized Black-Scholes-Merton equation

    NASA Astrophysics Data System (ADS)

    Bozhkov, Y.; Dimas, S.

    2014-07-01

    The complete group classification of a generalization of the Black-Scholes-Merton model is carried out by making use of the underlying equivalence and additional equivalence transformations. For each nonlinear case obtained through this classification, invariant solutions are given. To that end, two boundary conditions of financial interest are considered, the terminal and the barrier option conditions.

  1. Doubly robust estimation of generalized partial linear models for longitudinal data with dropouts.

    PubMed

    Lin, Huiming; Fu, Bo; Qin, Guoyou; Zhu, Zhongyi

    2017-04-03

    We develop a doubly robust estimation of generalized partial linear models for longitudinal data with dropouts. Our method extends the highly efficient aggregate unbiased estimating function approach proposed in Qu et al. (2010) to a doubly robust one in the sense that under missing at random (MAR), our estimator is consistent when either the linear conditional mean condition is satisfied or a model for the dropout process is correctly specified. We begin with a generalized linear model for the marginal mean, and then move forward to a generalized partial linear model, allowing for nonparametric covariate effect by using the regression spline smoothing approximation. We establish the asymptotic theory for the proposed method and use simulation studies to compare its finite sample performance with that of Qu's method, the complete-case generalized estimating equation (GEE) and the inverse-probability weighted GEE. The proposed method is finally illustrated using data from a longitudinal cohort study.

  2. Linear response theory for the density matrix renormalization group: efficient algorithms for strongly correlated excited states.

    PubMed

    Nakatani, Naoki; Wouters, Sebastian; Van Neck, Dimitri; Chan, Garnet Kin-Lic

    2014-01-14

    Linear response theory for the density matrix renormalization group (DMRG-LRT) was first presented in terms of the DMRG renormalization projectors [J. J. Dorando, J. Hachmann, and G. K.-L. Chan, J. Chem. Phys. 130, 184111 (2009)]. Later, with an understanding of the manifold structure of the matrix product state (MPS) ansatz, which lies at the basis of the DMRG algorithm, a way was found to construct the linear response space for general choices of the MPS gauge in terms of the tangent space vectors [J. Haegeman, J. I. Cirac, T. J. Osborne, I. Pižorn, H. Verschelde, and F. Verstraete, Phys. Rev. Lett. 107, 070601 (2011)]. These two developments led to the formulation of the Tamm-Dancoff and random phase approximations (TDA and RPA) for MPS. This work describes how these LRTs may be efficiently implemented through minor modifications of the DMRG sweep algorithm, at a computational cost which scales the same as the ground-state DMRG algorithm. In fact, the mixed canonical MPS form implicit to the DMRG sweep is essential for efficient implementation of the RPA, due to the structure of the second-order tangent space. We present ab initio DMRG-TDA results for excited states of polyenes, the water molecule, and a [2Fe-2S] iron-sulfur cluster.

  3. Linear response theory for the density matrix renormalization group: Efficient algorithms for strongly correlated excited states

    NASA Astrophysics Data System (ADS)

    Nakatani, Naoki; Wouters, Sebastian; Van Neck, Dimitri; Chan, Garnet Kin-Lic

    2014-01-01

    Linear response theory for the density matrix renormalization group (DMRG-LRT) was first presented in terms of the DMRG renormalization projectors [J. J. Dorando, J. Hachmann, and G. K.-L. Chan, J. Chem. Phys. 130, 184111 (2009)]. Later, with an understanding of the manifold structure of the matrix product state (MPS) ansatz, which lies at the basis of the DMRG algorithm, a way was found to construct the linear response space for general choices of the MPS gauge in terms of the tangent space vectors [J. Haegeman, J. I. Cirac, T. J. Osborne, I. Pižorn, H. Verschelde, and F. Verstraete, Phys. Rev. Lett. 107, 070601 (2011)]. These two developments led to the formulation of the Tamm-Dancoff and random phase approximations (TDA and RPA) for MPS. This work describes how these LRTs may be efficiently implemented through minor modifications of the DMRG sweep algorithm, at a computational cost which scales the same as the ground-state DMRG algorithm. In fact, the mixed canonical MPS form implicit to the DMRG sweep is essential for efficient implementation of the RPA, due to the structure of the second-order tangent space. We present ab initio DMRG-TDA results for excited states of polyenes, the water molecule, and a [2Fe-2S] iron-sulfur cluster.

  4. Grouping in sparse random-dot patterns: linear and nonlinear mechanisms

    NASA Astrophysics Data System (ADS)

    Kashi, Ramanujan S.; Papathomas, Thomas V.; Gorea, Andrei

    1997-06-01

    This study reports on experiments conducted with human observers to investigate the properties of linear and non- linear, perceptual grouping mechanisms by using reverse- polarity sparse random-dot patterns. The stimuli were generated by spatially superimposing a sparse set of randomly distributed square elements onto a copy of the original set that was expanded or rotated about the center of the screen. In the control experiment both the original and transformed sets contained elements of identical luminance contrast with the background. The main experiments involved a reverse- contrast random-dot pattern, in which the transformed set consisted of elements of equal contrast magnitude but opposite polarity to that of the original set. At least two competing global percepts are possible: 'forward grouping' in which perceived grouping agrees with the physical transformation; or 'reverse grouping' in a direction orthogonal to that of the 'forward grouping.' The two-alternative forced-choice (2AFC) task was to report the direction of the global grouping. For the control experiment, the observers reported forward grouping both at the fovea and eccentricities of up to 4 degrees; as expected, no reverse grouping was observed. With the reverse-polarity stimulus, reverse grouping was observed at high eccentricities and low contrasts, but forward grouping dominated under foveal viewing. In another experiment, the influence of chromatic mechanisms was studied by using opposite-contrast red elements on a yellow background. In this experiment reverse grouping was not observed, which indicates that color mechanisms veto reverse grouping. Reverse grouping can be hypothesized to be the result of processing by linear oriented spatial mechanisms, in analogy with reverse-phi motion. Forward grouping, on the other hand, can be explained by non-linear preprocessing (such s squaring or full-wave rectification).

  5. Flexible Approaches to Computing Mediated Effects in Generalized Linear Models: Generalized Estimating Equations and Bootstrapping

    ERIC Educational Resources Information Center

    Schluchter, Mark D.

    2008-01-01

    In behavioral research, interest is often in examining the degree to which the effect of an independent variable X on an outcome Y is mediated by an intermediary or mediator variable M. This article illustrates how generalized estimating equations (GEE) modeling can be used to estimate the indirect or mediated effect, defined as the amount by…

  6. An efficient method for generalized linear multiplicative programming problem with multiplicative constraints.

    PubMed

    Zhao, Yingfeng; Liu, Sanyang

    2016-01-01

    We present a practical branch and bound algorithm for globally solving generalized linear multiplicative programming problem with multiplicative constraints. To solve the problem, a relaxation programming problem which is equivalent to a linear programming is proposed by utilizing a new two-phase relaxation technique. In the algorithm, lower and upper bounds are simultaneously obtained by solving some linear relaxation programming problems. Global convergence has been proved and results of some sample examples and a small random experiment show that the proposed algorithm is feasible and efficient.

  7. Generalized entropies and the transformation group of superstatistics

    PubMed Central

    Hanel, Rudolf; Thurner, Stefan; Gell-Mann, Murray

    2011-01-01

    Superstatistics describes statistical systems that behave like superpositions of different inverse temperatures β, so that the probability distribution is , where the “kernel” f(β) is nonnegative and normalized [∫f(β)dβ = 1]. We discuss the relation between this distribution and the generalized entropic form . The first three Shannon–Khinchin axioms are assumed to hold. It then turns out that for a given distribution there are two different ways to construct the entropy. One approach uses escort probabilities and the other does not; the question of which to use must be decided empirically. The two approaches are related by a duality. The thermodynamic properties of the system can be quite different for the two approaches. In that connection, we present the transformation laws for the superstatistical distributions under macroscopic state changes. The transformation group is the Euclidean group in one dimension.

  8. Group Lifting Structures For Multirate Filter Banks, II: Linear Phase Filter Banks

    SciTech Connect

    Brislawn, Christopher M

    2008-01-01

    The theory of group lifting structures is applied to linear phase lifting factorizations for the two nontrivial classes of two-channel linear phase perfect reconstruction filter banks, the whole-and half-sample symmetric classes. Group lifting structures defined for the reversible and irreversible classes of whole-and half-sample symmetric filter banks are shown to satisfy the hypotheses of the uniqueness theorem for group lifting structures. It follows that linear phase lifting factorizations of whole-and half-sample symmetric filter banks are therefore independent of the factorization methods used to compute them. These results cover the specification of user-defined whole-sample symmetric filter banks in Part 2 of the ISO JPEG 2000 standard.

  9. Summary goodness-of-fit statistics for binary generalized linear models with noncanonical link functions.

    PubMed

    Canary, Jana D; Blizzard, Leigh; Barry, Ronald P; Hosmer, David W; Quinn, Stephen J

    2016-05-01

    Generalized linear models (GLM) with a canonical logit link function are the primary modeling technique used to relate a binary outcome to predictor variables. However, noncanonical links can offer more flexibility, producing convenient analytical quantities (e.g., probit GLMs in toxicology) and desired measures of effect (e.g., relative risk from log GLMs). Many summary goodness-of-fit (GOF) statistics exist for logistic GLM. Their properties make the development of GOF statistics relatively straightforward, but it can be more difficult under noncanonical links. Although GOF tests for logistic GLM with continuous covariates (GLMCC) have been applied to GLMCCs with log links, we know of no GOF tests in the literature specifically developed for GLMCCs that can be applied regardless of link function chosen. We generalize the Tsiatis GOF statistic originally developed for logistic GLMCCs, (TG), so that it can be applied under any link function. Further, we show that the algebraically related Hosmer-Lemeshow (HL) and Pigeon-Heyse (J(2) ) statistics can be applied directly. In a simulation study, TG, HL, and J(2) were used to evaluate the fit of probit, log-log, complementary log-log, and log models, all calculated with a common grouping method. The TG statistic consistently maintained Type I error rates, while those of HL and J(2) were often lower than expected if terms with little influence were included. Generally, the statistics had similar power to detect an incorrect model. An exception occurred when a log GLMCC was incorrectly fit to data generated from a logistic GLMCC. In this case, TG had more power than HL or J(2) .

  10. A generalized concordance correlation coefficient based on the variance components generalized linear mixed models for overdispersed count data.

    PubMed

    Carrasco, Josep L

    2010-09-01

    The classical concordance correlation coefficient (CCC) to measure agreement among a set of observers assumes data to be distributed as normal and a linear relationship between the mean and the subject and observer effects. Here, the CCC is generalized to afford any distribution from the exponential family by means of the generalized linear mixed models (GLMMs) theory and applied to the case of overdispersed count data. An example of CD34+ cell count data is provided to show the applicability of the procedure. In the latter case, different CCCs are defined and applied to the data by changing the GLMM that fits the data. A simulation study is carried out to explore the behavior of the procedure with a small and moderate sample size.

  11. Elliptical galaxies kinematics within general relativity with renormalization group effects

    SciTech Connect

    Rodrigues, Davi C.

    2012-09-01

    The renormalization group framework can be applied to Quantum Field Theory on curved space-time, but there is no proof whether the beta-function of the gravitational coupling indeed goes to zero in the far infrared or not. In a recent paper [1] we have shown that the amount of dark matter inside spiral galaxies may be negligible if a small running of the General Relativity coupling G is present (δG/G{sub 0}∼<10{sup −7} across a galaxy). Here we extend the proposed model to elliptical galaxies and present a detailed analysis on the modeling of NGC 4494 (an ordinary elliptical) and NGC 4374 (a giant elliptical). In order to compare our results to a well known alternative model to the standard dark matter picture, we also evaluate NGC 4374 with MOND. In this galaxy MOND leads to a significative discrepancy with the observed velocity dispersion curve and has a significative tendency towards tangential anisotropy. On the other hand, the approach based on the renormalization group and general relativity (RGGR) could be applied with good results to these elliptical galaxies and is compatible with lower mass-to-light ratios (of about the Kroupa IMF type)

  12. Linear and nonlinear associations between general intelligence and personality in Project TALENT.

    PubMed

    Major, Jason T; Johnson, Wendy; Deary, Ian J

    2014-04-01

    Research on the relations of personality traits to intelligence has primarily been concerned with linear associations. Yet, there are no a priori reasons why linear relations should be expected over nonlinear ones, which represent a much larger set of all possible associations. Using 2 techniques, quadratic and generalized additive models, we tested for linear and nonlinear associations of general intelligence (g) with 10 personality scales from Project TALENT (PT), a nationally representative sample of approximately 400,000 American high school students from 1960, divided into 4 grade samples (Flanagan et al., 1962). We departed from previous studies, including one with PT (Reeve, Meyer, & Bonaccio, 2006), by modeling latent quadratic effects directly, controlling the influence of the common factor in the personality scales, and assuming a direction of effect from g to personality. On the basis of the literature, we made 17 directional hypotheses for the linear and quadratic associations. Of these, 53% were supported in all 4 male grades and 58% in all 4 female grades. Quadratic associations explained substantive variance above and beyond linear effects (mean R² between 1.8% and 3.6%) for Sociability, Maturity, Vigor, and Leadership in males and Sociability, Maturity, and Tidiness in females; linear associations were predominant for other traits. We discuss how suited current theories of the personality-intelligence interface are to explain these associations, and how research on intellectually gifted samples may provide a unique way of understanding them. We conclude that nonlinear models can provide incremental detail regarding personality and intelligence associations.

  13. Study of linear and nonlinear optical properties of dendrimers using density matrix renormalization group method

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Ramasesha, S.

    2009-08-01

    We have used the density matrix renormalization group (DMRG) method to study the linear and nonlinear optical responses of first generation nitrogen based dendrimers with donor acceptor groups. We have employed Pariser-Parr-Pople Hamiltonian to model the interacting π electrons in these systems. Within the DMRG method we have used an innovative scheme to target excited states with large transition dipole to the ground state. This method reproduces exact optical gaps and polarization in systems where exact diagonalization of the Hamiltonian is possible. We have used a correction vector method which tacitly takes into account the contribution of all excited states, to obtain the ground state polarizibility, first hyperpolarizibility, and two photon absorption cross sections. We find that the lowest optical excitations as well as the lowest excited triplet states are localized. It is interesting to note that the first hyperpolarizibility saturates more rapidly with system size compared to linear polarizibility unlike that of linear polyenes.

  14. Study of linear and nonlinear optical properties of dendrimers using density matrix renormalization group method.

    PubMed

    Mukhopadhyay, S; Ramasesha, S

    2009-08-21

    We have used the density matrix renormalization group (DMRG) method to study the linear and nonlinear optical responses of first generation nitrogen based dendrimers with donor acceptor groups. We have employed Pariser-Parr-Pople Hamiltonian to model the interacting pi electrons in these systems. Within the DMRG method we have used an innovative scheme to target excited states with large transition dipole to the ground state. This method reproduces exact optical gaps and polarization in systems where exact diagonalization of the Hamiltonian is possible. We have used a correction vector method which tacitly takes into account the contribution of all excited states, to obtain the ground state polarizibility, first hyperpolarizibility, and two photon absorption cross sections. We find that the lowest optical excitations as well as the lowest excited triplet states are localized. It is interesting to note that the first hyperpolarizibility saturates more rapidly with system size compared to linear polarizibility unlike that of linear polyenes.

  15. Three-photon circular dichroism: towards a generalization of chiroptical non-linear light absorption.

    PubMed

    Friese, Daniel H; Ruud, Kenneth

    2016-02-07

    We present the theory of three-photon circular dichroism (3PCD), a novel non-linear chiroptical property not yet described in the literature. We derive the observable absorption cross section including the orientational average of the necessary seventh-rank tensors and provide origin-independent expressions for 3PCD using either a velocity-gauge treatment of the electric dipole operator or a length-gauge formulation using London atomic orbitals. We present the first numerical results for hydrogen peroxide, 3-methylcyclopentanone (MCP) and 4-helicene, including also a study of the origin dependence and basis set convergence of 3PCD. We find that for the 3PCD-brightest low-lying Rydberg state of hydrogen peroxide, the dichroism is extremely basis set dependent, with basis set convergence not being reached before a sextuple-zeta basis is used, whereas for the MCP and 4-helicene molecules, the basis set dependence is more moderate and at the triple-zeta level the 3PCD contributions are more or less converged irrespective of whether the considered states are Rydberg states or not. The character of the 3PCD-brightest states in MCP is characterized by a fairly large charge-transfer character from the carbonyl group to the ring system. In general, the quadrupole contributions to 3PCD are found to be very small.

  16. Regression Is a Univariate General Linear Model Subsuming Other Parametric Methods as Special Cases.

    ERIC Educational Resources Information Center

    Vidal, Sherry

    Although the concept of the general linear model (GLM) has existed since the 1960s, other univariate analyses such as the t-test and the analysis of variance models have remained popular. The GLM produces an equation that minimizes the mean differences of independent variables as they are related to a dependent variable. From a computer printout…

  17. Estimation of Complex Generalized Linear Mixed Models for Measurement and Growth

    ERIC Educational Resources Information Center

    Jeon, Minjeong

    2012-01-01

    Maximum likelihood (ML) estimation of generalized linear mixed models (GLMMs) is technically challenging because of the intractable likelihoods that involve high dimensional integrations over random effects. The problem is magnified when the random effects have a crossed design and thus the data cannot be reduced to small independent clusters. A…

  18. Prediction of formability for non-linear deformation history using generalized forming limit concept (GFLC)

    NASA Astrophysics Data System (ADS)

    Volk, Wolfram; Suh, Joungsik

    2013-12-01

    The prediction of formability is one of the most important tasks in sheet metal process simulation. The common criterion in industrial applications is the Forming Limit Curve (FLC). The big advantage of FLCs is the easy interpretation of simulation or measurement data in combination with an ISO standard for the experimental determination. However, the conventional FLCs are limited to almost linear and unbroken strain paths, i.e. deformation histories with non-linear strain increments often lead to big differences in comparison to the prediction of the FLC. In this paper a phenomenological approach, the so-called Generalized Forming Limit Concept (GFLC), is introduced to predict the localized necking on arbitrary deformation history with unlimited number of non-linear strain increments. The GFLC consists of the conventional FLC and an acceptable number of experiments with bi-linear deformation history. With the idea of the new defined "Principle of Equivalent Pre-Forming" every deformation state built up of two linear strain increments can be transformed to a pure linear strain path with the same used formability of the material. In advance this procedure can be repeated as often as necessary. Therefore, it allows a robust and cost effective analysis of beginning instability in Finite Element Analysis (FEA) for arbitrary deformation histories. In addition, the GFLC is fully downwards compatible to the established FLC for pure linear strain paths.

  19. Secret Message Decryption: Group Consulting Projects Using Matrices and Linear Programming

    ERIC Educational Resources Information Center

    Gurski, Katharine F.

    2009-01-01

    We describe two short group projects for finite mathematics students that incorporate matrices and linear programming into fictional consulting requests presented as a letter to the students. The students are required to use mathematics to decrypt secret messages in one project involving matrix multiplication and inversion. The second project…

  20. Implementing general quantum measurements on linear optical and solid-state qubits

    NASA Astrophysics Data System (ADS)

    Ota, Yukihiro; Ashhab, Sahel; Nori, Franco

    2013-03-01

    We show a systematic construction for implementing general measurements on a single qubit, including both strong (or projection) and weak measurements. We mainly focus on linear optical qubits. The present approach is composed of simple and feasible elements, i.e., beam splitters, wave plates, and polarizing beam splitters. We show how the parameters characterizing the measurement operators are controlled by the linear optical elements. We also propose a method for the implementation of general measurements in solid-state qubits. Furthermore, we show an interesting application of the general measurements, i.e., entanglement amplification. YO is partially supported by the SPDR Program, RIKEN. SA and FN acknowledge ARO, NSF grant No. 0726909, JSPS-RFBR contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.

  1. The linear stability of plane stagnation-point flow against general disturbances

    NASA Astrophysics Data System (ADS)

    Brattkus, K.; Davis, S. H.

    1991-02-01

    The linear-stability theory of plane stagnation-point flow against an infinite flat plate is re-examined. Disturbances are generalized from those of Goertler type to include other types of variations along the plate. It is shown that Hiemenz flow is linearly stable and that the Goertler-type modes are those that decay slowest. This work then rationalizes the use of such self-similar disturbances on Hiemenz flow and shows how questions of disturbance structure can be approached on other self-similar flows.

  2. The linear stability of plane stagnation-point flow against general disturbances

    NASA Technical Reports Server (NTRS)

    Brattkus, K.; Davis, S. H.

    1991-01-01

    The linear-stability theory of plane stagnation-point flow against an infinite flat plate is re-examined. Disturbances are generalized from those of Goertler type to include other types of variations along the plate. It is shown that Hiemenz flow is linearly stable and that the Goertler-type modes are those that decay slowest. This work then rationalizes the use of such self-similar disturbances on Hiemenz flow and shows how questions of disturbance structure can be approached on other self-similar flows.

  3. Estimate of influenza cases using generalized linear, additive and mixed models.

    PubMed

    Oviedo, Manuel; Domínguez, Ángela; Pilar Muñoz, M

    2015-01-01

    We investigated the relationship between reported cases of influenza in Catalonia (Spain). Covariates analyzed were: population, age, data of report of influenza, and health region during 2010-2014 using data obtained from the SISAP program (Institut Catala de la Salut - Generalitat of Catalonia). Reported cases were related with the study of covariates using a descriptive analysis. Generalized Linear Models, Generalized Additive Models and Generalized Additive Mixed Models were used to estimate the evolution of the transmission of influenza. Additive models can estimate non-linear effects of the covariates by smooth functions; and mixed models can estimate data dependence and variability in factor variables using correlations structures and random effects, respectively. The incidence rate of influenza was calculated as the incidence per 100 000 people. The mean rate was 13.75 (range 0-27.5) in the winter months (December, January, February) and 3.38 (range 0-12.57) in the remaining months. Statistical analysis showed that Generalized Additive Mixed Models were better adapted to the temporal evolution of influenza (serial correlation 0.59) than classical linear models.

  4. Generalized approach to global renormalization-group theory for fluids

    NASA Astrophysics Data System (ADS)

    Ramana, A. Sai Venkata; Menon, S. V. G.

    2012-04-01

    The global renormalization-group theory (GRGT) for fluids is derived starting with the square-gradient approximation for the Helmholtz free energy functional such that any mean-field free energy density and direct correlation function can be employed. The new derivation uses Wilson's functions for representing density fluctuations, thereby relaxing the assumption of cosine variation of density fluctuations used in earlier approaches. The generality of the present approach is shown by deriving the relationships to the earlier developments. A qualitative way to infer the free parameters in the present form of GRGT is also suggested. The new theory is applied to square-well fluids of ranges 1.5 and 3.0 (in units of hard-sphere diameter) and Lennard-Jones fluids. It is shown that the present theory produces a flat isotherm in the two-phase region. Thus the theory accounts for fluctuations at all length scales and avoids the use of Maxwell's construction. An analysis of the liquid-vapor phase diagrams and the critical constants obtained for different potentials shows that, with a mean-field free energy density that is accurate away from the critical region and an appropriate coarse graining length for the mean-field theory, GRGT can provide results in good agreement with the simulation and experimental results.

  5. Semiparametric Analysis of Heterogeneous Data Using Varying-Scale Generalized Linear Models.

    PubMed

    Xie, Minge; Simpson, Douglas G; Carroll, Raymond J

    2008-01-01

    This article describes a class of heteroscedastic generalized linear regression models in which a subset of the regression parameters are rescaled nonparametrically, and develops efficient semiparametric inferences for the parametric components of the models. Such models provide a means to adapt for heterogeneity in the data due to varying exposures, varying levels of aggregation, and so on. The class of models considered includes generalized partially linear models and nonparametrically scaled link function models as special cases. We present an algorithm to estimate the scale function nonparametrically, and obtain asymptotic distribution theory for regression parameter estimates. In particular, we establish that the asymptotic covariance of the semiparametric estimator for the parametric part of the model achieves the semiparametric lower bound. We also describe bootstrap-based goodness-of-scale test. We illustrate the methodology with simulations, published data, and data from collaborative research on ultrasound safety.

  6. A regularized point process generalized linear model for assessing the functional connectivity in the cat motor cortex.

    PubMed

    Chen, Zhe; Putrino, David F; Ba, Demba E; Ghosh, Soumya; Barbieri, Riccardo; Brown, Emery N

    2009-01-01

    Identification of multiple simultaneously recorded neural spike train recordings is an important task in understanding neuronal dependency, functional connectivity, and temporal causality in neural systems. An assessment of the functional connectivity in a group of ensemble cells was performed using a regularized point process generalized linear model (GLM) that incorporates temporal smoothness or contiguity of the solution. An efficient convex optimization algorithm was then developed for the regularized solution. The point process model was applied to an ensemble of neurons recorded from the cat motor cortex during a skilled reaching task. The implications of this analysis to the coding of skilled movement in primary motor cortex is discussed.

  7. A review of linear response theory for general differentiable dynamical systems

    NASA Astrophysics Data System (ADS)

    Ruelle, David

    2009-04-01

    The classical theory of linear response applies to statistical mechanics close to equilibrium. Away from equilibrium, one may describe the microscopic time evolution by a general differentiable dynamical system, identify nonequilibrium steady states (NESS) and study how these vary under perturbations of the dynamics. Remarkably, it turns out that for uniformly hyperbolic dynamical systems (those satisfying the 'chaotic hypothesis'), the linear response away from equilibrium is very similar to the linear response close to equilibrium: the Kramers-Kronig dispersion relations hold, and the fluctuation-dispersion theorem survives in a modified form (which takes into account the oscillations around the 'attractor' corresponding to the NESS). If the chaotic hypothesis does not hold, two new phenomena may arise. The first is a violation of linear response in the sense that the NESS does not depend differentiably on parameters (but this nondifferentiability may be hard to see experimentally). The second phenomenon is a violation of the dispersion relations: the susceptibility has singularities in the upper half complex plane. These 'acausal' singularities are actually due to 'energy nonconservation': for a small periodic perturbation of the system, the amplitude of the linear response is arbitrarily large. This means that the NESS of the dynamical system under study is not 'inert' but can give energy to the outside world. An 'active' NESS of this sort is very different from an equilibrium state, and it would be interesting to see what happens for active states to the Gallavotti-Cohen fluctuation theorem.

  8. Invariance of the generalized oscillator under a linear transformation of the related system of orthogonal polynomials

    NASA Astrophysics Data System (ADS)

    Borzov, V. V.; Damaskinsky, E. V.

    2017-02-01

    We consider the families of polynomials P = { P n ( x)} n=0 ∞ and Q = { Q n ( x)} n=0 ∞ orthogonal on the real line with respect to the respective probability measures μ and ν. We assume that { Q n ( x)} n=0 ∞ and { P n ( x)} n=0 ∞ are connected by linear relations. In the case k = 2, we describe all pairs (P,Q) for which the algebras A P and A Q of generalized oscillators generated by { Qn(x)} n=0 ∞ and { Pn(x)} n=0 ∞ coincide. We construct generalized oscillators corresponding to pairs (P,Q) for arbitrary k ≥ 1.

  9. Construction of invariants of the coadjoint representation of Lie groups using linear algebra methods

    NASA Astrophysics Data System (ADS)

    Kurnyavko, O. L.; Shirokov, I. V.

    2016-07-01

    We offer a method for constructing invariants of the coadjoint representation of Lie groups that reduces this problem to known problems of linear algebra. This method is based on passing to symplectic coordinates on the coadjoint representation orbits, which play the role of local coordinates on those orbits. The corresponding transition functions are their parametric equations. Eliminating the symplectic coordinates from the transition functions, we can obtain the complete set of invariants. The proposed method allows solving the problem of constructing invariants of the coadjoint representation for Lie groups with an arbitrary dimension and structure.

  10. Application of the Hyper-Poisson Generalized Linear Model for Analyzing Motor Vehicle Crashes.

    PubMed

    Khazraee, S Hadi; Sáez-Castillo, Antonio Jose; Geedipally, Srinivas Reddy; Lord, Dominique

    2015-05-01

    The hyper-Poisson distribution can handle both over- and underdispersion, and its generalized linear model formulation allows the dispersion of the distribution to be observation-specific and dependent on model covariates. This study's objective is to examine the potential applicability of a newly proposed generalized linear model framework for the hyper-Poisson distribution in analyzing motor vehicle crash count data. The hyper-Poisson generalized linear model was first fitted to intersection crash data from Toronto, characterized by overdispersion, and then to crash data from railway-highway crossings in Korea, characterized by underdispersion. The results of this study are promising. When fitted to the Toronto data set, the goodness-of-fit measures indicated that the hyper-Poisson model with a variable dispersion parameter provided a statistical fit as good as the traditional negative binomial model. The hyper-Poisson model was also successful in handling the underdispersed data from Korea; the model performed as well as the gamma probability model and the Conway-Maxwell-Poisson model previously developed for the same data set. The advantages of the hyper-Poisson model studied in this article are noteworthy. Unlike the negative binomial model, which has difficulties in handling underdispersed data, the hyper-Poisson model can handle both over- and underdispersed crash data. Although not a major issue for the Conway-Maxwell-Poisson model, the effect of each variable on the expected mean of crashes is easily interpretable in the case of this new model.

  11. Experimenting Clinical Pathways in General Practice: a Focus Group Investigation with Italian General Practitioners

    PubMed Central

    Zannini, Lucia; Cattaneo, Cesarina; Peduzzi, Paolo; Lopiccoli, Silvia; Auxilia, Francesco

    2012-01-01

    Background Clinical governance is considered crucial in primary care. Since 2005, clinical pathways have been experimentally implemented at the Local Health Authority of Monza Brianza (ASLMB), Italy, to develop general practitioners’ (GPs) care of patients affected by some chronic diseases. The experimentation was aimed at introducing clinical governance in primary care, increasing GPs’ involvement in the care of their patients, and improving both patients’ and professionals’ satisfaction. In the period 2005-2006, 12% of the 763 employed GPs in the ASLMB were involved in the experiment, while this percentage increased to 15-20% in 2007-2008. Design and Methods Twenty-four GPs were purposively sampled, randomly divided into two groups and asked to participate in focus groups (FGs) held in 2008, aimed at evaluating their perception of the experiment. The FGs were audio-recorded, dialogues were typed out and undergone to a thematic analysis, according to the Interpretative Phenomenological Approach. Results Four major themes emerged: i) clinical pathways can result in GPs working in a more efficient and effective fashion; ii) they can assure higher levels of both patient and professional satisfaction, since they sustain a caring approach and strengthen the GPs’ role; iii) nevertheless, clinical pathways increase the bureaucratic workload and problems can arise in relationships among GPs and the LHA; iv) the implementation of clinical pathways can be improved, especially by reducing bureaucracy and by assuring their continuity. Conclusions Managerial aspects should be considered with care in order to experimentally introduce clinical pathways in general practice, and continuity of the experimentation should be guaranteed to improve GPs’ adherence and commitment. Acknowledgments the Authors thank Dr. AP. Cantù and Dr D. Cereda who participated in the two focus groups as observers. PMID:25181354

  12. Incorporating More Individual Accountability in Group Activities in General Chemistry

    ERIC Educational Resources Information Center

    Cox, Charles T., Jr.

    2015-01-01

    A modified model of cooperative learning known as the GIG model (for group-individual-group) designed and implemented in a large enrollment freshman chemistry course. The goal of the model is to establish a cooperative environment while emphasizing greater individual accountability using both group and individual assignments. The assignments were…

  13. Unified Einstein-Virasoro Master Equation in the General Non-Linear Sigma Model

    SciTech Connect

    Boer, J. de; Halpern, M.B.

    1996-06-05

    The Virasoro master equation (VME) describes the general affine-Virasoro construction $T=L^abJ_aJ_b+iD^a \\dif J_a$ in the operator algebra of the WZW model, where $L^ab$ is the inverse inertia tensor and $D^a $ is the improvement vector. In this paper, we generalize this construction to find the general (one-loop) Virasoro construction in the operator algebra of the general non-linear sigma model. The result is a unified Einstein-Virasoro master equation which couples the spacetime spin-two field $L^ab$ to the background fields of the sigma model. For a particular solution $L_G^ab$, the unified system reduces to the canonical stress tensors and conventional Einstein equations of the sigma model, and the system reduces to the general affine-Virasoro construction and the VME when the sigma model is taken to be the WZW action. More generally, the unified system describes a space of conformal field theories which is presumably much larger than the sum of the general affine-Virasoro construction and the sigma model with its canonical stress tensors. We also discuss a number of algebraic and geometrical properties of the system, including its relation to an unsolved problem in the theory of $G$-structures on manifolds with torsion.

  14. Fitting host-parasitoid models with CV2 > 1 using hierarchical generalized linear models.

    PubMed Central

    Perry, J N; Noh, M S; Lee, Y; Alston, R D; Norowi, H M; Powell, W; Rennolls, K

    2000-01-01

    The powerful general Pacala-Hassell host-parasitoid model for a patchy environment, which allows host density-dependent heterogeneity (HDD) to be distinguished from between-patch, host density-independent heterogeneity (HDI), is reformulated within the class of the generalized linear model (GLM) family. This improves accessibility through the provision of general software within well-known statistical systems, and allows a rich variety of models to be formulated. Covariates such as age class, host density and abiotic factors may be included easily. For the case where there is no HDI, the formulation is a simple GLM. When there is HDI in addition to HDD, the formulation is a hierarchical generalized linear model. Two forms of HDI model are considered, both with between-patch variability: one has binomial variation within patches and one has extra-binomial, overdispersed variation within patches. Examples are given demonstrating parameter estimation with standard errors, and hypothesis testing. For one example given, the extra-binomial component of the HDI heterogeneity in parasitism is itself shown to be strongly density dependent. PMID:11416907

  15. A method for assigning species into groups based on generalized Mahalanobis distance between habitat model coefficients

    USGS Publications Warehouse

    Williams, C.J.; Heglund, P.J.

    2009-01-01

    Habitat association models are commonly developed for individual animal species using generalized linear modeling methods such as logistic regression. We considered the issue of grouping species based on their habitat use so that management decisions can be based on sets of species rather than individual species. This research was motivated by a study of western landbirds in northern Idaho forests. The method we examined was to separately fit models to each species and to use a generalized Mahalanobis distance between coefficient vectors to create a distance matrix among species. Clustering methods were used to group species from the distance matrix, and multidimensional scaling methods were used to visualize the relations among species groups. Methods were also discussed for evaluating the sensitivity of the conclusions because of outliers or influential data points. We illustrate these methods with data from the landbird study conducted in northern Idaho. Simulation results are presented to compare the success of this method to alternative methods using Euclidean distance between coefficient vectors and to methods that do not use habitat association models. These simulations demonstrate that our Mahalanobis-distance- based method was nearly always better than Euclidean-distance-based methods or methods not based on habitat association models. The methods used to develop candidate species groups are easily explained to other scientists and resource managers since they mainly rely on classical multivariate statistical methods. ?? 2008 Springer Science+Business Media, LLC.

  16. Normality of raw data in general linear models: The most widespread myth in statistics

    USGS Publications Warehouse

    Kery, Marc; Hatfield, Jeff S.

    2003-01-01

    In years of statistical consulting for ecologists and wildlife biologists, by far the most common misconception we have come across has been the one about normality in general linear models. These comprise a very large part of the statistical models used in ecology and include t tests, simple and multiple linear regression, polynomial regression, and analysis of variance (ANOVA) and covariance (ANCOVA). There is a widely held belief that the normality assumption pertains to the raw data rather than to the model residuals. We suspect that this error may also occur in countless published studies, whenever the normality assumption is tested prior to analysis. This may lead to the use of nonparametric alternatives (if there are any), when parametric tests would indeed be appropriate, or to use of transformations of raw data, which may introduce hidden assumptions such as multiplicative effects on the natural scale in the case of log-transformed data. Our aim here is to dispel this myth. We very briefly describe relevant theory for two cases of general linear models to show that the residuals need to be normally distributed if tests requiring normality are to be used, such as t and F tests. We then give two examples demonstrating that the distribution of the response variable may be nonnormal, and yet the residuals are well behaved. We do not go into the issue of how to test normality; instead we display the distributions of response variables and residuals graphically.

  17. On linear groups of degree 2 over a finite commutative ring

    SciTech Connect

    Bashkirov, Evgenii L.; Eser, Hasan

    2014-08-20

    Let p > 3 be a prime number and F{sub p} be a field of p elements. Let K be a commutative and associative ring obtained by adjoining to F{sub p} an element α such that α satisfies a polynomial over F{sub p} and a polynomial of the least degree whose root is α can be written as a product of distinct polynomials irreducible over F{sub p}. We prove that the special linear group SL{sub 2}(K) is generated by two elementary transvections ( (table) ), ( (table) )

  18. Fast and local non-linear evolution of steep wave-groups on deep water: A comparison of approximate models to fully non-linear simulations

    SciTech Connect

    Adcock, T. A. A.; Taylor, P. H.

    2016-01-15

    The non-linear Schrödinger equation and its higher order extensions are routinely used for analysis of extreme ocean waves. This paper compares the evolution of individual wave-packets modelled using non-linear Schrödinger type equations with packets modelled using fully non-linear potential flow models. The modified non-linear Schrödinger Equation accurately models the relatively large scale non-linear changes to the shape of wave-groups, with a dramatic contraction of the group along the mean propagation direction and a corresponding extension of the width of the wave-crests. In addition, as extreme wave form, there is a local non-linear contraction of the wave-group around the crest which leads to a localised broadening of the wave spectrum which the bandwidth limited non-linear Schrödinger Equations struggle to capture. This limitation occurs for waves of moderate steepness and a narrow underlying spectrum.

  19. Random generalized linear model: a highly accurate and interpretable ensemble predictor

    PubMed Central

    2013-01-01

    Background Ensemble predictors such as the random forest are known to have superior accuracy but their black-box predictions are difficult to interpret. In contrast, a generalized linear model (GLM) is very interpretable especially when forward feature selection is used to construct the model. However, forward feature selection tends to overfit the data and leads to low predictive accuracy. Therefore, it remains an important research goal to combine the advantages of ensemble predictors (high accuracy) with the advantages of forward regression modeling (interpretability). To address this goal several articles have explored GLM based ensemble predictors. Since limited evaluations suggested that these ensemble predictors were less accurate than alternative predictors, they have found little attention in the literature. Results Comprehensive evaluations involving hundreds of genomic data sets, the UCI machine learning benchmark data, and simulations are used to give GLM based ensemble predictors a new and careful look. A novel bootstrap aggregated (bagged) GLM predictor that incorporates several elements of randomness and instability (random subspace method, optional interaction terms, forward variable selection) often outperforms a host of alternative prediction methods including random forests and penalized regression models (ridge regression, elastic net, lasso). This random generalized linear model (RGLM) predictor provides variable importance measures that can be used to define a “thinned” ensemble predictor (involving few features) that retains excellent predictive accuracy. Conclusion RGLM is a state of the art predictor that shares the advantages of a random forest (excellent predictive accuracy, feature importance measures, out-of-bag estimates of accuracy) with those of a forward selected generalized linear model (interpretability). These methods are implemented in the freely available R software package randomGLM. PMID:23323760

  20. A Comparison between Linear IRT Observed-Score Equating and Levine Observed-Score Equating under the Generalized Kernel Equating Framework

    ERIC Educational Resources Information Center

    Chen, Haiwen

    2012-01-01

    In this article, linear item response theory (IRT) observed-score equating is compared under a generalized kernel equating framework with Levine observed-score equating for nonequivalent groups with anchor test design. Interestingly, these two equating methods are closely related despite being based on different methodologies. Specifically, when…

  1. On the linear representations of the symmetry groups of single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cotfas, Nicolae

    2006-08-01

    The positions of atoms forming a carbon nanotube are usually described by using a system of generators of the symmetry group. Each atomic position corresponds to an element of the set {\\bb Z}\\times \\{0,1,\\ldots,n\\} \\times \\{0,1\\} , where n depends on the considered nanotube. We obtain an alternative, rather different description by starting from a three-axes description of the honeycomb lattice. In our mathematical model, which is a factor space defined by an equivalence relation in the set \\{(v_0,v_1,v_2)\\in {\\bb Z}^3\\mid v_0+v_1+v_2\\in \\{0,1\\}\\} , the neighbours of an atomic position can be described in a simpler way, and the mathematical objects with geometric or physical significance have a simpler and more symmetric form. We present some results concerning the linear representations of the symmetry groups of single-wall carbon nanotubes in order to illustrate the proposed approach.

  2. Linear and nonlinear quantification of respiratory sinus arrhythmia during propofol general anesthesia.

    PubMed

    Chen, Zhe; Purdon, Patrick L; Pierce, Eric T; Harrell, Grace; Walsh, John; Salazar, Andres F; Tavares, Casie L; Brown, Emery N; Barbieri, Riccardo

    2009-01-01

    Quantitative evaluation of respiratory sinus arrhythmia (RSA) may provide important information in clinical practice of anesthesia and postoperative care. In this paper, we apply a point process method to assess dynamic RSA during propofol general anesthesia. Specifically, an inverse Gaussian probability distribution is used to model the heartbeat interval, whereas the instantaneous mean is identified by a linear or bilinear bivariate regression on the previous R-R intervals and respiratory measures. The estimated second-order bilinear interaction allows us to evaluate the nonlinear component of the RSA. The instantaneous RSA gain and phase can be estimated with an adaptive point process filter. The algorithm's ability to track non-stationary dynamics is demonstrated using one clinical recording. Our proposed statistical indices provide a valuable quantitative assessment of instantaneous cardiorespiratory control and heart rate variability (HRV) during general anesthesia.

  3. Neutron source strength measurements for Varian, Siemens, Elekta, and General Electric linear accelerators.

    PubMed

    Followill, David S; Stovall, Marilyn S; Kry, Stephen F; Ibbott, Geoffrey S

    2003-01-01

    The shielding calculations for high energy (>10 MV) linear accelerators must include the photoneutron production within the head of the accelerator. Procedures have been described to calculate the treatment room door shielding based on the neutron source strength (Q value) for a specific accelerator and energy combination. Unfortunately, there is currently little data in the literature stating the neutron source strengths for the most widely used linear accelerators. In this study, the neutron fluence for 36 linear accelerators, including models from Varian, Siemens, Elekta/Philips, and General Electric, was measured using gold-foil activation. Several of the models and energy combinations had multiple measurements. The neutron fluence measured in the patient plane was independent of the surface area of the room, suggesting that neutron fluence is more dependent on the direct neutron fluence from the head of the accelerator than from room scatter. Neutron source strength, Q, was determined from the measured neutron fluences. As expected, Q increased with increasing photon energy. The Q values ranged from 0.02 for a 10 MV beam to 1.44(x10(12)) neutrons per photon Gy for a 25 MV beam. The most comprehensive set of neutron source strength values, Q, for the current accelerators in clinical use are presented for use in calculating room shielding.

  4. Wave packet dynamics in one-dimensional linear and nonlinear generalized Fibonacci lattices.

    PubMed

    Zhang, Zhenjun; Tong, Peiqing; Gong, Jiangbin; Li, Baowen

    2011-05-01

    The spreading of an initially localized wave packet in one-dimensional linear and nonlinear generalized Fibonacci (GF) lattices is studied numerically. The GF lattices can be classified into two classes depending on whether or not the lattice possesses the Pisot-Vijayaraghavan property. For linear GF lattices of the first class, both the second moment and the participation number grow with time. For linear GF lattices of the second class, in the regime of a weak on-site potential, wave packet spreading is close to ballistic diffusion, whereas in the regime of a strong on-site potential, it displays stairlike growth in both the second moment and the participation number. Nonlinear GF lattices are then investigated in parallel. For the first class of nonlinear GF lattices, the second moment of the wave packet still grows with time, but the corresponding participation number does not grow simultaneously. For the second class of nonlinear GF lattices, an analogous phenomenon is observed for the weak on-site potential only. For a strong on-site potential that leads to an enhanced nonlinear self-trapping effect, neither the second moment nor the participation number grows with time. The results can be useful in guiding experiments on the expansion of noninteracting or interacting cold atoms in quasiperiodic optical lattices.

  5. Thermodynamic bounds and general properties of optimal efficiency and power in linear responses

    NASA Astrophysics Data System (ADS)

    Jiang, Jian-Hua

    2014-10-01

    We study the optimal exergy efficiency and power for thermodynamic systems with an Onsager-type "current-force" relationship describing the linear response to external influences. We derive, in analytic forms, the maximum efficiency and optimal efficiency for maximum power for a thermodynamic machine described by a N ×N symmetric Onsager matrix with arbitrary integer N. The figure of merit is expressed in terms of the largest eigenvalue of the "coupling matrix" which is solely determined by the Onsager matrix. Some simple but general relationships between the power and efficiency at the conditions for (i) maximum efficiency and (ii) optimal efficiency for maximum power are obtained. We show how the second law of thermodynamics bounds the optimal efficiency and the Onsager matrix and relate those bounds together. The maximum power theorem (Jacobi's Law) is generalized to all thermodynamic machines with a symmetric Onsager matrix in the linear-response regime. We also discuss systems with an asymmetric Onsager matrix (such as systems under magnetic field) for a particular situation and we show that the reversible limit of efficiency can be reached at finite output power. Cooperative effects are found to improve the figure of merit significantly in systems with multiply cross-correlated responses. Application to example systems demonstrates that the theory is helpful in guiding the search for high performance materials and structures in energy researches.

  6. On General Issues of Bilingual Education for Minority Ethnic Groups

    ERIC Educational Resources Information Center

    Mingyuan, Gu

    2014-01-01

    Minority language literacy is an important issue in national education policy for any multi-nationality country. China sticks to the policy of safeguarding the rights and interests of ethnic minority groups to use their own languages and writing systems. In education, considering communications among different nationalities and the development of…

  7. On Parametrization of the Linear GL(4,C) and Unitary SU(4) Groups in Terms of Dirac Matrices

    NASA Astrophysics Data System (ADS)

    Red'Kov, Victor M.; Bogush, Andrei A.; Tokarevskaya, Natalia G.

    2008-02-01

    Parametrization of 4 × 4-matrices G of the complex linear group GL(4,C) in terms of four complex 4-vector parameters (k,m,n,l) is investigated. Additional restrictions separating some subgroups of GL(4,C) are given explicitly. In the given parametrization, the problem of inverting any 4 × 4 matrix G is solved. Expression for determinant of any matrix G is found: det G = F(k,m,n,l). Unitarity conditions G+ = G-1 have been formulated in the form of non-linear cubic algebraic equations including complex conjugation. Several simplest solutions of these unitarity equations have been found: three 2-parametric subgroups G1, G2, G3 - each of subgroups consists of two commuting Abelian unitary groups; 4-parametric unitary subgroup consis! ting of a product of a 3-parametric group isomorphic SU(2) and 1-parametric Abelian group. The Dirac basis of generators Λk, being of Gell-Mann type, substantially differs from the basis λi used in the literature on SU(4) group, formulas relating them are found - they permit to separate SU(3) subgroup in SU(4). Special way to list 15 Dirac generators of GL(4,C) can be used {Λk} = {μiÅνjÅ(μiVνj = KÅL ÅM )}, which permit to factorize SU(4) transformations according to S = eiaμ eibνeikKeilLeimM, where two first factors commute with each other and are isomorphic to SU(2) group, the three last ones are 3-parametric groups, each of them consisting of three Abelian commuting unitary subgroups. Besides, the structure of fifteen Dirac matrices Λk permits to separate twenty 3-parametric subgroups in SU(4) isomorphic to SU(2); those subgroups might be used as bigger elementary blocks in constructing of a general transformation SU(4). It is shown how one can specify the present approach for the pseudounitary group SU(2,2) and SU(3,1).

  8. On relating the generalized equivalent uniform dose formalism to the linear-quadratic model.

    PubMed

    Djajaputra, David; Wu, Qiuwen

    2006-12-01

    Two main approaches are commonly used in the literature for computing the equivalent uniform dose (EUD) in radiotherapy. The first approach is based on the cell-survival curve as defined in the linear-quadratic model. The second approach assumes that EUD can be computed as the generalized mean of the dose distribution with an appropriate fitting parameter. We have analyzed the connection between these two formalisms by deriving explicit formulas for the EUD which are applicable to normal distributions. From these formulas we have established an explicit connection between the two formalisms. We found that the EUD parameter has strong dependence on the parameters that characterize the distribution, namely the mean dose and the standard deviation around the mean. By computing the corresponding parameters for clinical dose distributions, which in general do not follow the normal distribution, we have shown that our results are also applicable to actual dose distributions. Our analysis suggests that caution should be used in using generalized EUD approach for reporting and analyzing dose distributions.

  9. Ab initio characterization of the quantum linear-zigzag transition using density matrix renormalization group calculations

    NASA Astrophysics Data System (ADS)

    Silvi, Pietro; Calarco, Tommaso; Morigi, Giovanna; Montangero, Simone

    2014-03-01

    Ions of the same charge inside confining potentials can form crystalline structures which can be controlled by means of the ion density and of the external trap parameters. In particular, a linear chain of trapped ions exhibits a transition to a zigzag equilibrium configuration, which is controlled by the strength of the transverse confinement. Studying this phase transition in the quantum regime is a challenging problem, even when employing numerical methods to simulate microscopically quantum many-body systems. Here we present a compact analytical treatment to map the original long-range problem into a short-range quantum field theory on a lattice. We provide a complete numerical architecture, based on the density matrix renormalization group, to address the effective quantum ϕ4 model. This technique is instrumental in giving a complete characterization of the phase diagram, as well as pinpointing the universality class of the criticality.

  10. Model Averaging Methods for Weight Trimming in Generalized Linear Regression Models.

    PubMed

    Elliott, Michael R

    2009-03-01

    In sample surveys where units have unequal probabilities of inclusion, associations between the inclusion probability and the statistic of interest can induce bias in unweighted estimates. This is true even in regression models, where the estimates of the population slope may be biased if the underlying mean model is misspecified or the sampling is nonignorable. Weights equal to the inverse of the probability of inclusion are often used to counteract this bias. Highly disproportional sample designs have highly variable weights; weight trimming reduces large weights to a maximum value, reducing variability but introducing bias. Most standard approaches are ad hoc in that they do not use the data to optimize bias-variance trade-offs. This article uses Bayesian model averaging to create "data driven" weight trimming estimators. We extend previous results for linear regression models (Elliott 2008) to generalized linear regression models, developing robust models that approximate fully-weighted estimators when bias correction is of greatest importance, and approximate unweighted estimators when variance reduction is critical.

  11. A generalized fuzzy linear programming approach for environmental management problem under uncertainty.

    PubMed

    Fan, Yurui; Huang, Guohe; Veawab, Amornvadee

    2012-01-01

    In this study, a generalized fuzzy linear programming (GFLP) method was developed to deal with uncertainties expressed as fuzzy sets that exist in the constraints and objective function. A stepwise interactive algorithm (SIA) was advanced to solve GFLP model and generate solutions expressed as fuzzy sets. To demonstrate its application, the developed GFLP method was applied to a regional sulfur dioxide (SO2) control planning model to identify effective SO2 mitigation polices with a minimized system performance cost under uncertainty. The results were obtained to represent the amount of SO2 allocated to different control measures from different sources. Compared with the conventional interval-parameter linear programming (ILP) approach, the solutions obtained through GFLP were expressed as fuzzy sets, which can provide intervals for the decision variables and objective function, as well as related possibilities. Therefore, the decision makers can make a tradeoff between model stability and the plausibility based on solutions obtained through GFLP and then identify desired policies for SO2-emission control under uncertainty.

  12. Two-stage method of estimation for general linear growth curve models.

    PubMed

    Stukel, T A; Demidenko, E

    1997-06-01

    We extend the linear random-effects growth curve model (REGCM) (Laird and Ware, 1982, Biometrics 38, 963-974) to study the effects of population covariates on one or more characteristics of the growth curve when the characteristics are expressed as linear combinations of the growth curve parameters. This definition includes the actual growth curve parameters (the usual model) or any subset of these parameters. Such an analysis would be cumbersome using standard growth curve methods because it would require reparameterization of the original growth curve. We implement a two-stage method of estimation based on the two-stage growth curve model used to describe the response. The resulting generalized least squares (GLS) estimator for the population parameters is consistent, asymptotically efficient, and multivariate normal when the number of individuals is large. It is also robust to model misspecification in terms of bias and efficiency of the parameter estimates compared to maximum likelihood with the usual REGCM. We apply the method to a study of factors affecting the growth rate of salmonellae in a cubic growth model, a characteristic that cannot be analyzed easily using standard techniques.

  13. Compact tunable silicon photonic differential-equation solver for general linear time-invariant systems.

    PubMed

    Wu, Jiayang; Cao, Pan; Hu, Xiaofeng; Jiang, Xinhong; Pan, Ting; Yang, Yuxing; Qiu, Ciyuan; Tremblay, Christine; Su, Yikai

    2014-10-20

    We propose and experimentally demonstrate an all-optical temporal differential-equation solver that can be used to solve ordinary differential equations (ODEs) characterizing general linear time-invariant (LTI) systems. The photonic device implemented by an add-drop microring resonator (MRR) with two tunable interferometric couplers is monolithically integrated on a silicon-on-insulator (SOI) wafer with a compact footprint of ~60 μm × 120 μm. By thermally tuning the phase shifts along the bus arms of the two interferometric couplers, the proposed device is capable of solving first-order ODEs with two variable coefficients. The operation principle is theoretically analyzed, and system testing of solving ODE with tunable coefficients is carried out for 10-Gb/s optical Gaussian-like pulses. The experimental results verify the effectiveness of the fabricated device as a tunable photonic ODE solver.

  14. General linear codes for fault-tolerant matrix operations on processor arrays

    NASA Technical Reports Server (NTRS)

    Nair, V. S. S.; Abraham, J. A.

    1988-01-01

    Various checksum codes have been suggested for fault-tolerant matrix computations on processor arrays. Use of these codes is limited due to potential roundoff and overflow errors. Numerical errors may also be misconstrued as errors due to physical faults in the system. In this a set of linear codes is identified which can be used for fault-tolerant matrix operations such as matrix addition, multiplication, transposition, and LU-decomposition, with minimum numerical error. Encoding schemes are given for some of the example codes which fall under the general set of codes. With the help of experiments, a rule of thumb for the selection of a particular code for a given application is derived.

  15. Generalization of the ordinary state-based peridynamic model for isotropic linear viscoelasticity

    NASA Astrophysics Data System (ADS)

    Delorme, Rolland; Tabiai, Ilyass; Laberge Lebel, Louis; Lévesque, Martin

    2017-02-01

    This paper presents a generalization of the original ordinary state-based peridynamic model for isotropic linear viscoelasticity. The viscoelastic material response is represented using the thermodynamically acceptable Prony series approach. It can feature as many Prony terms as required and accounts for viscoelastic spherical and deviatoric components. The model was derived from an equivalence between peridynamic viscoelastic parameters and those appearing in classical continuum mechanics, by equating the free energy densities expressed in both frameworks. The model was simplified to a uni-dimensional expression and implemented to simulate a creep-recovery test. This implementation was finally validated by comparing peridynamic predictions to those predicted from classical continuum mechanics. An exact correspondence between peridynamics and the classical continuum approach was shown when the peridynamic horizon becomes small, meaning peridynamics tends toward classical continuum mechanics. This work provides a clear and direct means to researchers dealing with viscoelastic phenomena to tackle their problem within the peridynamic framework.

  16. Towards downscaling precipitation for Senegal - An approach based on generalized linear models and weather types

    NASA Astrophysics Data System (ADS)

    Rust, H. W.; Vrac, M.; Lengaigne, M.; Sultan, B.

    2012-04-01

    Changes in precipitation patterns with potentially less precipitation and an increasing risk for droughts pose a threat to water resources and agricultural yields in Senegal. Precipitation in this region is dominated by the West-African Monsoon being active from May to October, a seasonal pattern with inter-annual to decadal variability in the 20th century which is likely to be affected by climate change. We built a generalized linear model for a full spatial description of rainfall in Senegal. The model uses season, location, and a discrete set of weather types as predictors and yields a spatially continuous description of precipitation occurrences and intensities. Weather types have been defined on NCEP/NCAR reanalysis using zonal and meridional winds, as well as relative humidity. This model is suitable for downscaling precipitation, particularly precipitation occurrences relevant for drough risk mapping.

  17. Solving the Linear Balance Equation on the Globe as a Generalized Inverse Problem

    NASA Technical Reports Server (NTRS)

    Lu, Huei-Iin; Robertson, Franklin R.

    1999-01-01

    A generalized (pseudo) inverse technique was developed to facilitate a better understanding of the numerical effects of tropical singularities inherent in the spectral linear balance equation (LBE). Depending upon the truncation, various levels of determinancy are manifest. The traditional fully-determined (FD) systems give rise to a strong response, while the under-determined (UD) systems yield a weak response to the tropical singularities. The over-determined (OD) systems result in a modest response and a large residual in the tropics. The FD and OD systems can be alternatively solved by the iterative method. Differences in the solutions of an UD system exist between the inverse technique and the iterative method owing to the non- uniqueness of the problem. A realistic balanced wind was obtained by solving the principal components of the spectral LBE in terms of vorticity in an intermediate resolution. Improved solutions were achieved by including the singular-component solutions which best fit the observed wind data.

  18. Comparing a single case to a control group - Applying linear mixed effects models to repeated measures data.

    PubMed

    Huber, Stefan; Klein, Elise; Moeller, Korbinian; Willmes, Klaus

    2015-10-01

    In neuropsychological research, single-cases are often compared with a small control sample. Crawford and colleagues developed inferential methods (i.e., the modified t-test) for such a research design. In the present article, we suggest an extension of the methods of Crawford and colleagues employing linear mixed models (LMM). We first show that a t-test for the significance of a dummy coded predictor variable in a linear regression is equivalent to the modified t-test of Crawford and colleagues. As an extension to this idea, we then generalized the modified t-test to repeated measures data by using LMMs to compare the performance difference in two conditions observed in a single participant to that of a small control group. The performance of LMMs regarding Type I error rates and statistical power were tested based on Monte-Carlo simulations. We found that starting with about 15-20 participants in the control sample Type I error rates were close to the nominal Type I error rate using the Satterthwaite approximation for the degrees of freedom. Moreover, statistical power was acceptable. Therefore, we conclude that LMMs can be applied successfully to statistically evaluate performance differences between a single-case and a control sample.

  19. A Bayesian approach for inducing sparsity in generalized linear models with multi-category response

    PubMed Central

    2015-01-01

    Background The dimension and complexity of high-throughput gene expression data create many challenges for downstream analysis. Several approaches exist to reduce the number of variables with respect to small sample sizes. In this study, we utilized the Generalized Double Pareto (GDP) prior to induce sparsity in a Bayesian Generalized Linear Model (GLM) setting. The approach was evaluated using a publicly available microarray dataset containing 99 samples corresponding to four different prostate cancer subtypes. Results A hierarchical Sparse Bayesian GLM using GDP prior (SBGG) was developed to take into account the progressive nature of the response variable. We obtained an average overall classification accuracy between 82.5% and 94%, which was higher than Support Vector Machine, Random Forest or a Sparse Bayesian GLM using double exponential priors. Additionally, SBGG outperforms the other 3 methods in correctly identifying pre-metastatic stages of cancer progression, which can prove extremely valuable for therapeutic and diagnostic purposes. Importantly, using Geneset Cohesion Analysis Tool, we found that the top 100 genes produced by SBGG had an average functional cohesion p-value of 2.0E-4 compared to 0.007 to 0.131 produced by the other methods. Conclusions Using GDP in a Bayesian GLM model applied to cancer progression data results in better subclass prediction. In particular, the method identifies pre-metastatic stages of prostate cancer with substantially better accuracy and produces more functionally relevant gene sets. PMID:26423345

  20. Dental treatment under general anesthesia in a group of patients with cerebral palsy and a group of healthy pediatric patients

    PubMed Central

    Escanilla-Casal, Alejandro; Aznar-Gómez, Mirella; Viaño, José M.; Rivera-Baró, Alejandro

    2014-01-01

    This is a comparative study between two groups, one of healthy children and the other of children with cerebral palsy, which underwent dental treatment under general anesthesia at Hospital Sant Joan de Déu Barcelona. The purpose of the study was to compare and determine oral pathology, frequency, severity and postoperative complications in pediatric patients with and without an underlying disease which undergo a dental treatment under general anesthesia. Key words:General anesthesia, cerebral palsy, pediatric patients. PMID:24608223

  1. 26 CFR 1.79-1 - Group-term life insurance-general rules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Group-term life insurance-general rules. 1.79-1...-term life insurance—general rules. (a) What is group-term life insurance? Life insurance is not group-term life insurance for purposes of section 79 unless it meets the following conditions: (1)...

  2. Solutions for Determining the Significance Region Using the Johnson-Neyman Type Procedure in Generalized Linear (Mixed) Models.

    PubMed

    Lazar, Ann A; Zerbe, Gary O

    2011-12-01

    Researchers often compare the relationship between an outcome and covariate for two or more groups by evaluating whether the fitted regression curves differ significantly. When they do, researchers need to determine the "significance region," or the values of the covariate where the curves significantly differ. In analysis of covariance (ANCOVA), the Johnson-Neyman procedure can be used to determine the significance region; for the hierarchical linear model (HLM), the Miyazaki and Maier (M-M) procedure has been suggested. However, neither procedure can assume nonnormally distributed data. Furthermore, the M-M procedure produces biased (downward) results because it uses the Wald test, does not control the inflated Type I error rate due to multiple testing, and requires implementing multiple software packages to determine the significance region. In this article, we address these limitations by proposing solutions for determining the significance region suitable for generalized linear (mixed) model (GLM or GLMM). These proposed solutions incorporate test statistics that resolve the biased results, control the Type I error rate using Scheffé's method, and uses a single statistical software package to determine the significance region.

  3. General linear response formula for non integrable systems obeying the Vlasov equation

    NASA Astrophysics Data System (ADS)

    Patelli, Aurelio; Ruffo, Stefano

    2014-11-01

    Long-range interacting N-particle systems get trapped into long-living out-of-equilibrium stationary states called quasi-stationary states (QSS). We study here the response to a small external perturbation when such systems are settled into a QSS. In the N → ∞ limit the system is described by the Vlasov equation and QSS are mapped into stable stationary solutions of such equation. We consider this problem in the context of a model that has recently attracted considerable attention, the Hamiltonian mean field (HMF) model. For such a model, stationary inhomogeneous and homogeneous states determine an integrable dynamics in the mean-field effective potential and an action-angle transformation allows one to derive an exact linear response formula. However, such a result would be of limited interest if restricted to the integrable case. In this paper, we show how to derive a general linear response formula which does not use integrability as a requirement. The presence of conservation laws (mass, energy, momentum, etc.) and of further Casimir invariants can be imposed a posteriori. We perform an analysis of the infinite time asymptotics of the response formula for a specific observable, the magnetization in the HMF model, as a result of the application of an external magnetic field, for two stationary stable distributions: the Boltzmann-Gibbs equilibrium distribution and the Fermi-Dirac one. When compared with numerical simulations the predictions of the theory are very good away from the transition energy from inhomogeneous to homogeneous states. Contribution to the Topical Issue "Theory and Applications of the Vlasov Equation", edited by Francesco Pegoraro, Francesco Califano, Giovanni Manfredi and Philip J. Morrison.

  4. Linear propargylic alcohol functionality attached to the indazole-7-carboxamide as a JAK1-specific linear probe group.

    PubMed

    Kim, Mi Kyoung; Shin, Heerim; Cho, Seo Young; Chong, Youhoon

    2014-02-01

    Selective inhibition of JAK1 has recently been proposed as an appropriate therapeutic rationale for the treatment of inflammatory diseases such as rheumatoid arthritis (RA). In this study, through pairwise comparison and 3D alignment of the JAK isozyme structures bound to the same inhibitor molecule, we reasoned that an alkynol functionality would serve as an isozyme-specific probe group, which would enable the resulting inhibitor to differentiate the ATP-binding site of JAK1 from those of other isozymes. The 3-alkynolyl-5-(4'-indazolyl)indazole-7-carboxamide derivatives were thus prepared, and in vitro evaluation of their inhibitory activity against the JAK isozymes revealed that the propargyl alcohol functionality endowed the 5-(4'-indazolyl)indazole-7-carboxamide scaffold with JAK1 selectivity over other JAK isozymes, particularly JAK2.

  5. Development and validation of a general purpose linearization program for rigid aircraft models

    NASA Technical Reports Server (NTRS)

    Duke, E. L.; Antoniewicz, R. F.

    1985-01-01

    A FORTRAN program that provides the user with a powerful and flexible tool for the linearization of aircraft models is discussed. The program LINEAR numerically determines a linear systems model using nonlinear equations of motion and a user-supplied, nonlinear aerodynamic model. The system model determined by LINEAR consists of matrices for both the state and observation equations. The program has been designed to allow easy selection and definition of the state, control, and observation variables to be used in a particular model. Also, included in the report is a comparison of linear and nonlinear models for a high performance aircraft.

  6. Predicting estuarine use patterns of juvenile fish with Generalized Linear Models

    NASA Astrophysics Data System (ADS)

    Vasconcelos, R. P.; Le Pape, O.; Costa, M. J.; Cabral, H. N.

    2013-03-01

    Statistical models are key for estimating fish distributions based on environmental variables, and validation is generally advocated as indispensable but seldom applied. Generalized Linear Models were applied to distributions of juvenile Solea solea, Solea senegalensis, Platichthys flesus and Dicentrarchus labrax in response to environmental variables throughout Portuguese estuaries. Species-specific Delta models with two sub-models were used: Binomial (presence/absence); Gamma (density when present). Models were fitted and tested on separate data sets to estimate the accuracy and robustness of predictions. Temperature, salinity and mud content in sediment were included in most models for presence/absence; salinity and depth in most models for density (when present). In Binomial models (presence/absence), goodness-of-fit, accuracy and robustness varied concurrently among species, and fair to high accuracy and robustness were attained for all species, in models with poor to high goodness-of-fit. But in Gamma models (density when present), goodness-of-fit was not indicative of accuracy and robustness. Only for Platichthys flesus were Gamma and also coupled Delta models (density) accurate and robust, despite some moderate bias and inconsistency in predicted density. The accuracy and robustness of final density estimations were defined by the accuracy and robustness of the estimations of presence/absence and density (when present) provided by the sub-models. The mismatches between goodness-of-fit, accuracy and robustness of positive density models, as well as the difference in performance of presence/absence and density models demonstrated the importance of validation procedures in the evaluation of the value of habitat suitability models as predictive tools.

  7. The overlooked potential of Generalized Linear Models in astronomy-II: Gamma regression and photometric redshifts

    NASA Astrophysics Data System (ADS)

    Elliott, J.; de Souza, R. S.; Krone-Martins, A.; Cameron, E.; Ishida, E. E. O.; Hilbe, J.

    2015-04-01

    Machine learning techniques offer a precious tool box for use within astronomy to solve problems involving so-called big data. They provide a means to make accurate predictions about a particular system without prior knowledge of the underlying physical processes of the data. In this article, and the companion papers of this series, we present the set of Generalized Linear Models (GLMs) as a fast alternative method for tackling general astronomical problems, including the ones related to the machine learning paradigm. To demonstrate the applicability of GLMs to inherently positive and continuous physical observables, we explore their use in estimating the photometric redshifts of galaxies from their multi-wavelength photometry. Using the gamma family with a log link function we predict redshifts from the PHoto-z Accuracy Testing simulated catalogue and a subset of the Sloan Digital Sky Survey from Data Release 10. We obtain fits that result in catastrophic outlier rates as low as ∼1% for simulated and ∼2% for real data. Moreover, we can easily obtain such levels of precision within a matter of seconds on a normal desktop computer and with training sets that contain merely thousands of galaxies. Our software is made publicly available as a user-friendly package developed in Python, R and via an interactive web application. This software allows users to apply a set of GLMs to their own photometric catalogues and generates publication quality plots with minimum effort. By facilitating their ease of use to the astronomical community, this paper series aims to make GLMs widely known and to encourage their implementation in future large-scale projects, such as the Large Synoptic Survey Telescope.

  8. MGMRES: A generalization of GMRES for solving large sparse nonsymmetric linear systems

    SciTech Connect

    Young, D.M.; Chen, J.Y.

    1994-12-31

    The authors are concerned with the solution of the linear system (1): Au = b, where A is a real square nonsingular matrix which is large, sparse and non-symmetric. They consider the use of Krylov subspace methods. They first choose an initial approximation u{sup (0)} to the solution {bar u} = A{sup {minus}1}B of (1). They also choose an auxiliary matrix Z which is nonsingular. For n = 1,2,{hor_ellipsis} they determine u{sup (n)} such that u{sup (n)} {minus} u{sup (0)}{epsilon}K{sub n}(r{sup (0)},A) where K{sub n}(r{sup (0)},A) is the (Krylov) subspace spanned by the Krylov vectors r{sup (0)}, Ar{sup (0)}, {hor_ellipsis}, A{sup n{minus}1}r{sup 0} and where r{sup (0)} = b{minus}Au{sup (0)}. If ZA is SPD they also require that (u{sup (n)}{minus}{bar u}, ZA(u{sup (n)}{minus}{bar u})) be minimized. If, on the other hand, ZA is not SPD, then they require that the Galerkin condition, (Zr{sup n}, v) = 0, be satisfied for all v{epsilon}K{sub n}(r{sup (0)}, A) where r{sup n} = b{minus}Au{sup (n)}. In this paper the authors consider a generalization of GMRES. This generalized method, which they refer to as `MGMRES`, is very similar to GMRES except that they let Z = A{sup T}Y where Y is a nonsingular matrix which is symmetric by not necessarily SPD.

  9. Efficient analysis of Q-level nested hierarchical general linear models given ignorable missing data.

    PubMed

    Shin, Yongyun; Raudenbush, Stephen W

    2013-09-28

    This article extends single-level missing data methods to efficient estimation of a Q-level nested hierarchical general linear model given ignorable missing data with a general missing pattern at any of the Q levels. The key idea is to reexpress a desired hierarchical model as the joint distribution of all variables including the outcome that are subject to missingness, conditional on all of the covariates that are completely observed and to estimate the joint model under normal theory. The unconstrained joint model, however, identifies extraneous parameters that are not of interest in subsequent analysis of the hierarchical model and that rapidly multiply as the number of levels, the number of variables subject to missingness, and the number of random coefficients grow. Therefore, the joint model may be extremely high dimensional and difficult to estimate well unless constraints are imposed to avoid the proliferation of extraneous covariance components at each level. Furthermore, the over-identified hierarchical model may produce considerably biased inferences. The challenge is to represent the constraints within the framework of the Q-level model in a way that is uniform without regard to Q; in a way that facilitates efficient computation for any number of Q levels; and also in a way that produces unbiased and efficient analysis of the hierarchical model. Our approach yields Q-step recursive estimation and imputation procedures whose qth-step computation involves only level-q data given higher-level computation components. We illustrate the approach with a study of the growth in body mass index analyzing a national sample of elementary school children.

  10. A theorem on orbit structures (strata) of compact linear Lie groups

    NASA Astrophysics Data System (ADS)

    Sartori, G.

    1983-04-01

    We present a comprehensive constructive proof of a theorem characterizing the tangent space to a stratum (orbit structure) of the Euclidean space Rn, seat of an orthogonal representation of a compact group G. The characterization is made in terms of gradients of a complete set (integrity basis) of G-invariant polynomials. In a recent paper [M. Abud and G. Sartori, Phys. Lett. B 104, 147 (1981)], the theorem, which may be considered a generalization of a theorem by Michel [C. R. Acad. Sci. Ser. A 272, 433 (1971)], has been shown to be effective in the determination of the equations of the strata and in the determination of natural extrema of G-invariant functions.

  11. Generalized linear discriminant analysis: a unified framework and efficient model selection.

    PubMed

    Ji, Shuiwang; Ye, Jieping

    2008-10-01

    High-dimensional data are common in many domains, and dimensionality reduction is the key to cope with the curse-of-dimensionality. Linear discriminant analysis (LDA) is a well-known method for supervised dimensionality reduction. When dealing with high-dimensional and low sample size data, classical LDA suffers from the singularity problem. Over the years, many algorithms have been developed to overcome this problem, and they have been applied successfully in various applications. However, there is a lack of a systematic study of the commonalities and differences of these algorithms, as well as their intrinsic relationships. In this paper, a unified framework for generalized LDA is proposed, which elucidates the properties of various algorithms and their relationships. Based on the proposed framework, we show that the matrix computations involved in LDA-based algorithms can be simplified so that the cross-validation procedure for model selection can be performed efficiently. We conduct extensive experiments using a collection of high-dimensional data sets, including text documents, face images, gene expression data, and gene expression pattern images, to evaluate the proposed theories and algorithms.

  12. Profile local linear estimation of generalized semiparametric regression model for longitudinal data

    PubMed Central

    Sun, Liuquan; Zhou, Jie

    2013-01-01

    This paper studies the generalized semiparametric regression model for longitudinal data where the covariate effects are constant for some and time-varying for others. Different link functions can be used to allow more flexible modelling of longitudinal data. The nonparametric components of the model are estimated using a local linear estimating equation and the parametric components are estimated through a profile estimating function. The method automatically adjusts for heterogeneity of sampling times, allowing the sampling strategy to depend on the past sampling history as well as possibly time-dependent covariates without specifically model such dependence. A K -fold cross-validation bandwidth selection is proposed as a working tool for locating an appropriate bandwidth. A criteria for selecting the link function is proposed to provide better fit of the data. Large sample properties of the proposed estimators are investigated. Large sample pointwise and simultaneous confidence intervals for the regression coefficients are constructed. Formal hypothesis testing procedures are proposed to check for the covariate effects and whether the effects are time-varying. A simulation study is conducted to examine the finite sample performances of the proposed estimation and hypothesis testing procedures. The methods are illustrated with a data example. PMID:23471814

  13. Projecting nuisance flooding in a warming climate using generalized linear models and Gaussian processes

    NASA Astrophysics Data System (ADS)

    Vandenberg-Rodes, Alexander; Moftakhari, Hamed R.; AghaKouchak, Amir; Shahbaba, Babak; Sanders, Brett F.; Matthew, Richard A.

    2016-11-01

    Nuisance flooding corresponds to minor and frequent flood events that have significant socioeconomic and public health impacts on coastal communities. Yearly averaged local mean sea level can be used as proxy to statistically predict the impacts of sea level rise (SLR) on the frequency of nuisance floods (NFs). In this study, we use generalized linear models (GLM) and Gaussian Process (GP) models combined to (i) estimate the frequency of NF associated with the change in mean sea level, and (ii) quantify the associated uncertainties via a novel and statistically robust approach. We calibrate our models to the water level data from 18 tide gauges along the coasts of United States, and after validation, we estimate the frequency of NF associated with the SLR projections in year 2030 (under RCPs 2.6 and 8.5), along with their 90% bands, at each gauge. The historical NF-SLR data are very noisy, and show large changes in variability (heteroscedasticity) with SLR. Prior models in the literature do not properly account for the observed heteroscedasticity, and thus their projected uncertainties are highly suspect. Among the models used in this study, the Negative Binomial Distribution GLM with GP best characterizes the uncertainties associated with NF estimates; on validation data ≈93% of the points fall within the 90% credible limit, showing our approach to be a robust model for uncertainty quantification.

  14. Characterizing the performance of the Conway-Maxwell Poisson generalized linear model.

    PubMed

    Francis, Royce A; Geedipally, Srinivas Reddy; Guikema, Seth D; Dhavala, Soma Sekhar; Lord, Dominique; LaRocca, Sarah

    2012-01-01

    Count data are pervasive in many areas of risk analysis; deaths, adverse health outcomes, infrastructure system failures, and traffic accidents are all recorded as count events, for example. Risk analysts often wish to estimate the probability distribution for the number of discrete events as part of doing a risk assessment. Traditional count data regression models of the type often used in risk assessment for this problem suffer from limitations due to the assumed variance structure. A more flexible model based on the Conway-Maxwell Poisson (COM-Poisson) distribution was recently proposed, a model that has the potential to overcome the limitations of the traditional model. However, the statistical performance of this new model has not yet been fully characterized. This article assesses the performance of a maximum likelihood estimation method for fitting the COM-Poisson generalized linear model (GLM). The objectives of this article are to (1) characterize the parameter estimation accuracy of the MLE implementation of the COM-Poisson GLM, and (2) estimate the prediction accuracy of the COM-Poisson GLM using simulated data sets. The results of the study indicate that the COM-Poisson GLM is flexible enough to model under-, equi-, and overdispersed data sets with different sample mean values. The results also show that the COM-Poisson GLM yields accurate parameter estimates. The COM-Poisson GLM provides a promising and flexible approach for performing count data regression.

  15. Developing a methodology to predict PM10 concentrations in urban areas using generalized linear models.

    PubMed

    Garcia, J M; Teodoro, F; Cerdeira, R; Coelho, L M R; Kumar, Prashant; Carvalho, M G

    2016-09-01

    A methodology to predict PM10 concentrations in urban outdoor environments is developed based on the generalized linear models (GLMs). The methodology is based on the relationship developed between atmospheric concentrations of air pollutants (i.e. CO, NO2, NOx, VOCs, SO2) and meteorological variables (i.e. ambient temperature, relative humidity (RH) and wind speed) for a city (Barreiro) of Portugal. The model uses air pollution and meteorological data from the Portuguese monitoring air quality station networks. The developed GLM considers PM10 concentrations as a dependent variable, and both the gaseous pollutants and meteorological variables as explanatory independent variables. A logarithmic link function was considered with a Poisson probability distribution. Particular attention was given to cases with air temperatures both below and above 25°C. The best performance for modelled results against the measured data was achieved for the model with values of air temperature above 25°C compared with the model considering all ranges of air temperatures and with the model considering only temperature below 25°C. The model was also tested with similar data from another Portuguese city, Oporto, and results found to behave similarly. It is concluded that this model and the methodology could be adopted for other cities to predict PM10 concentrations when these data are not available by measurements from air quality monitoring stations or other acquisition means.

  16. A generalized linear model for peak calling in ChIP-Seq data.

    PubMed

    Xu, Jialin; Zhang, Yu

    2012-06-01

    Chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-Seq) has become a routine for detecting genome-wide protein-DNA interaction. The success of ChIP-Seq data analysis highly depends on the quality of peak calling (i.e., to detect peaks of tag counts at a genomic location and evaluate if the peak corresponds to a real protein-DNA interaction event). The challenges in peak calling include (1) how to combine the forward and the reverse strand tag data to improve the power of peak calling and (2) how to account for the variation of tag data observed across different genomic locations. We introduce a new peak calling method based on the generalized linear model (GLMNB) that utilizes negative binomial distribution to model the tag count data and account for the variation of background tags that may randomly bind to the DNA sequence at varying levels due to local genomic structures and sequence contents. We allow local shifting of peaks observed on the forward and the reverse stands, such that at each potential binding site, a binding profile representing the pattern of a real peak signal is fitted to best explain the observed tag data with maximum likelihood. Our method can also detect multiple peaks within a local region if there are multiple binding sites in the region.

  17. The overlooked potential of Generalized Linear Models in astronomy, I: Binomial regression

    NASA Astrophysics Data System (ADS)

    de Souza, R. S.; Cameron, E.; Killedar, M.; Hilbe, J.; Vilalta, R.; Maio, U.; Biffi, V.; Ciardi, B.; Riggs, J. D.

    2015-09-01

    Revealing hidden patterns in astronomical data is often the path to fundamental scientific breakthroughs; meanwhile the complexity of scientific enquiry increases as more subtle relationships are sought. Contemporary data analysis problems often elude the capabilities of classical statistical techniques, suggesting the use of cutting edge statistical methods. In this light, astronomers have overlooked a whole family of statistical techniques for exploratory data analysis and robust regression, the so-called Generalized Linear Models (GLMs). In this paper-the first in a series aimed at illustrating the power of these methods in astronomical applications-we elucidate the potential of a particular class of GLMs for handling binary/binomial data, the so-called logit and probit regression techniques, from both a maximum likelihood and a Bayesian perspective. As a case in point, we present the use of these GLMs to explore the conditions of star formation activity and metal enrichment in primordial minihaloes from cosmological hydro-simulations including detailed chemistry, gas physics, and stellar feedback. We predict that for a dark mini-halo with metallicity ≈ 1.3 × 10-4Z⨀, an increase of 1.2 × 10-2 in the gas molecular fraction, increases the probability of star formation occurrence by a factor of 75%. Finally, we highlight the use of receiver operating characteristic curves as a diagnostic for binary classifiers, and ultimately we use these to demonstrate the competitive predictive performance of GLMs against the popular technique of artificial neural networks.

  18. Fast inference in generalized linear models via expected log-likelihoods

    PubMed Central

    Ramirez, Alexandro D.; Paninski, Liam

    2015-01-01

    Generalized linear models play an essential role in a wide variety of statistical applications. This paper discusses an approximation of the likelihood in these models that can greatly facilitate computation. The basic idea is to replace a sum that appears in the exact log-likelihood by an expectation over the model covariates; the resulting “expected log-likelihood” can in many cases be computed significantly faster than the exact log-likelihood. In many neuroscience experiments the distribution over model covariates is controlled by the experimenter and the expected log-likelihood approximation becomes particularly useful; for example, estimators based on maximizing this expected log-likelihood (or a penalized version thereof) can often be obtained with orders of magnitude computational savings compared to the exact maximum likelihood estimators. A risk analysis establishes that these maximum EL estimators often come with little cost in accuracy (and in some cases even improved accuracy) compared to standard maximum likelihood estimates. Finally, we find that these methods can significantly decrease the computation time of marginal likelihood calculations for model selection and of Markov chain Monte Carlo methods for sampling from the posterior parameter distribution. We illustrate our results by applying these methods to a computationally-challenging dataset of neural spike trains obtained via large-scale multi-electrode recordings in the primate retina. PMID:23832289

  19. Fast inference in generalized linear models via expected log-likelihoods.

    PubMed

    Ramirez, Alexandro D; Paninski, Liam

    2014-04-01

    Generalized linear models play an essential role in a wide variety of statistical applications. This paper discusses an approximation of the likelihood in these models that can greatly facilitate computation. The basic idea is to replace a sum that appears in the exact log-likelihood by an expectation over the model covariates; the resulting "expected log-likelihood" can in many cases be computed significantly faster than the exact log-likelihood. In many neuroscience experiments the distribution over model covariates is controlled by the experimenter and the expected log-likelihood approximation becomes particularly useful; for example, estimators based on maximizing this expected log-likelihood (or a penalized version thereof) can often be obtained with orders of magnitude computational savings compared to the exact maximum likelihood estimators. A risk analysis establishes that these maximum EL estimators often come with little cost in accuracy (and in some cases even improved accuracy) compared to standard maximum likelihood estimates. Finally, we find that these methods can significantly decrease the computation time of marginal likelihood calculations for model selection and of Markov chain Monte Carlo methods for sampling from the posterior parameter distribution. We illustrate our results by applying these methods to a computationally-challenging dataset of neural spike trains obtained via large-scale multi-electrode recordings in the primate retina.

  20. Population decoding of motor cortical activity using a generalized linear model with hidden states.

    PubMed

    Lawhern, Vernon; Wu, Wei; Hatsopoulos, Nicholas; Paninski, Liam

    2010-06-15

    Generalized linear models (GLMs) have been developed for modeling and decoding population neuronal spiking activity in the motor cortex. These models provide reasonable characterizations between neural activity and motor behavior. However, they lack a description of movement-related terms which are not observed directly in these experiments, such as muscular activation, the subject's level of attention, and other internal or external states. Here we propose to include a multi-dimensional hidden state to address these states in a GLM framework where the spike count at each time is described as a function of the hand state (position, velocity, and acceleration), truncated spike history, and the hidden state. The model can be identified by an Expectation-Maximization algorithm. We tested this new method in two datasets where spikes were simultaneously recorded using a multi-electrode array in the primary motor cortex of two monkeys. It was found that this method significantly improves the model-fitting over the classical GLM, for hidden dimensions varying from 1 to 4. This method also provides more accurate decoding of hand state (reducing the mean square error by up to 29% in some cases), while retaining real-time computational efficiency. These improvements on representation and decoding over the classical GLM model suggest that this new approach could contribute as a useful tool to motor cortical decoding and prosthetic applications.

  1. Partitioning the set of subgroups of a finite group using Thompson's generalized characters

    NASA Astrophysics Data System (ADS)

    Doyle, Michael P.

    For a collection of subgroups P of a finite group G, we define the counting function psiP(g) = |{ x ∈ G: ∈ P }|. We partition the set of subgroups of G by defining an equivalence relation so that psiP is a generalized character for every equivalence class P. In some groups the equivalence relation can be refined to produce more generalized characters. We classify all refinements for elementary abelian p-groups of order p3, dihedral groups, and the direct product of a dihedral group of order 2 p and a cyclic group.

  2. 26 CFR 1.79-1 - Group-term life insurance-general rules.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... one dollar of paid-up whole-life insurance) at the employee's attained age at the beginning of the... 26 Internal Revenue 2 2013-04-01 2013-04-01 false Group-term life insurance-general rules. 1.79-1...-term life insurance—general rules. (a) What is group-term life insurance? Life insurance is not...

  3. 26 CFR 1.79-1 - Group-term life insurance-general rules.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... one dollar of paid-up whole-life insurance) at the employee's attained age at the beginning of the... 26 Internal Revenue 2 2012-04-01 2012-04-01 false Group-term life insurance-general rules. 1.79-1...-term life insurance—general rules. (a) What is group-term life insurance? Life insurance is not...

  4. A generalized harmonic balance method for forced non-linear oscillations: the subharmonic cases

    NASA Astrophysics Data System (ADS)

    Wu, J. J.

    1992-12-01

    This paper summarizes and extends results in two previous papers, published in conference proceedings, on a variant of the generalized harmonic balance method (GHB) and its application to obtain subharmonic solutions of forced non-linear oscillation problems. This method was introduced as an alternative to the method of multiple scales, and it essentially consists of two parts. First, the part of the multiple scales method used to reduce the problem to a set of differential equations is used to express the solution as a sum of terms of various harmonics with unknown, time dependent coefficients. Second, the form of solution so obtained is substituted into the original equation and the coefficients of each harmonic are set to zero. Key equations of approximations for a subharmonic case are derived for the cases of both "small" damping and excitations, and "Large" damping and excitations, which are shown to be identical, in the intended order of approximation, to those obtained by Nayfeh using the method of multiple scales. Detailed numerical formulations, including the derivation of the initial conditions, are presented, as well as some numerical results for the frequency-response relations and the time evolution of various harmonic components. Excellent agreement is demonstrated between results by GHB and by integrating the original differential equation directly. The improved efficiency in obtaining numerical solutions using GHB as compared with integrating the original differential equation is demonstrated also. For the case of large damping and excitations and for non-trivial solutions, it is noted that there exists a threshold value of the force beyond which no subharmonic excitations are possible.

  5. Generalized Functional Linear Models for Gene-based Case-Control Association Studies

    PubMed Central

    Mills, James L.; Carter, Tonia C.; Lobach, Iryna; Wilson, Alexander F.; Bailey-Wilson, Joan E.; Weeks, Daniel E.; Xiong, Momiao

    2014-01-01

    By using functional data analysis techniques, we developed generalized functional linear models for testing association between a dichotomous trait and multiple genetic variants in a genetic region while adjusting for covariates. Both fixed and mixed effect models are developed and compared. Extensive simulations show that Rao's efficient score tests of the fixed effect models are very conservative since they generate lower type I errors than nominal levels, and global tests of the mixed effect models generate accurate type I errors. Furthermore, we found that the Rao's efficient score test statistics of the fixed effect models have higher power than the sequence kernel association test (SKAT) and its optimal unified version (SKAT-O) in most cases when the causal variants are both rare and common. When the causal variants are all rare (i.e., minor allele frequencies less than 0.03), the Rao's efficient score test statistics and the global tests have similar or slightly lower power than SKAT and SKAT-O. In practice, it is not known whether rare variants or common variants in a gene are disease-related. All we can assume is that a combination of rare and common variants influences disease susceptibility. Thus, the improved performance of our models when the causal variants are both rare and common shows that the proposed models can be very useful in dissecting complex traits. We compare the performance of our methods with SKAT and SKAT-O on real neural tube defects and Hirschsprung's disease data sets. The Rao's efficient score test statistics and the global tests are more sensitive than SKAT and SKAT-O in the real data analysis. Our methods can be used in either gene-disease genome-wide/exome-wide association studies or candidate gene analyses. PMID:25203683

  6. Generalized functional linear models for gene-based case-control association studies.

    PubMed

    Fan, Ruzong; Wang, Yifan; Mills, James L; Carter, Tonia C; Lobach, Iryna; Wilson, Alexander F; Bailey-Wilson, Joan E; Weeks, Daniel E; Xiong, Momiao

    2014-11-01

    By using functional data analysis techniques, we developed generalized functional linear models for testing association between a dichotomous trait and multiple genetic variants in a genetic region while adjusting for covariates. Both fixed and mixed effect models are developed and compared. Extensive simulations show that Rao's efficient score tests of the fixed effect models are very conservative since they generate lower type I errors than nominal levels, and global tests of the mixed effect models generate accurate type I errors. Furthermore, we found that the Rao's efficient score test statistics of the fixed effect models have higher power than the sequence kernel association test (SKAT) and its optimal unified version (SKAT-O) in most cases when the causal variants are both rare and common. When the causal variants are all rare (i.e., minor allele frequencies less than 0.03), the Rao's efficient score test statistics and the global tests have similar or slightly lower power than SKAT and SKAT-O. In practice, it is not known whether rare variants or common variants in a gene region are disease related. All we can assume is that a combination of rare and common variants influences disease susceptibility. Thus, the improved performance of our models when the causal variants are both rare and common shows that the proposed models can be very useful in dissecting complex traits. We compare the performance of our methods with SKAT and SKAT-O on real neural tube defects and Hirschsprung's disease datasets. The Rao's efficient score test statistics and the global tests are more sensitive than SKAT and SKAT-O in the real data analysis. Our methods can be used in either gene-disease genome-wide/exome-wide association studies or candidate gene analyses.

  7. A general linear model-based approach for inferring selection to climate

    PubMed Central

    2013-01-01

    Background Many efforts have been made to detect signatures of positive selection in the human genome, especially those associated with expansion from Africa and subsequent colonization of all other continents. However, most approaches have not directly probed the relationship between the environment and patterns of variation among humans. We have designed a method to identify regions of the genome under selection based on Mantel tests conducted within a general linear model framework, which we call MAntel-GLM to Infer Clinal Selection (MAGICS). MAGICS explicitly incorporates population-specific and genome-wide patterns of background variation as well as information from environmental values to provide an improved picture of selection and its underlying causes in human populations. Results Our results significantly overlap with those obtained by other published methodologies, but MAGICS has several advantages. These include improvements that: limit false positives by reducing the number of independent tests conducted and by correcting for geographic distance, which we found to be a major contributor to selection signals; yield absolute rather than relative estimates of significance; identify specific geographic regions linked most strongly to particular signals of selection; and detect recent balancing as well as directional selection. Conclusions We find evidence of selection associated with climate (P < 10-5) in 354 genes, and among these observe a highly significant enrichment for directional positive selection. Two of our strongest 'hits’, however, ADRA2A and ADRA2C, implicated in vasoconstriction in response to cold and pain stimuli, show evidence of balancing selection. Our results clearly demonstrate evidence of climate-related signals of directional and balancing selection. PMID:24053227

  8. Protein structure validation by generalized linear model root-mean-square deviation prediction.

    PubMed

    Bagaria, Anurag; Jaravine, Victor; Huang, Yuanpeng J; Montelione, Gaetano T; Güntert, Peter

    2012-02-01

    Large-scale initiatives for obtaining spatial protein structures by experimental or computational means have accentuated the need for the critical assessment of protein structure determination and prediction methods. These include blind test projects such as the critical assessment of protein structure prediction (CASP) and the critical assessment of protein structure determination by nuclear magnetic resonance (CASD-NMR). An important aim is to establish structure validation criteria that can reliably assess the accuracy of a new protein structure. Various quality measures derived from the coordinates have been proposed. A universal structural quality assessment method should combine multiple individual scores in a meaningful way, which is challenging because of their different measurement units. Here, we present a method based on a generalized linear model (GLM) that combines diverse protein structure quality scores into a single quantity with intuitive meaning, namely the predicted coordinate root-mean-square deviation (RMSD) value between the present structure and the (unavailable) "true" structure (GLM-RMSD). For two sets of structural models from the CASD-NMR and CASP projects, this GLM-RMSD value was compared with the actual accuracy given by the RMSD value to the corresponding, experimentally determined reference structure from the Protein Data Bank (PDB). The correlation coefficients between actual (model vs. reference from PDB) and predicted (model vs. "true") heavy-atom RMSDs were 0.69 and 0.76, for the two datasets from CASD-NMR and CASP, respectively, which is considerably higher than those for the individual scores (-0.24 to 0.68). The GLM-RMSD can thus predict the accuracy of protein structures more reliably than individual coordinate-based quality scores.

  9. Determinants of hospital closure in South Korea: use of a hierarchical generalized linear model.

    PubMed

    Noh, Maengseok; Lee, Youngjo; Yun, Sung-Cheol; Lee, Sang-Il; Lee, Moo-Song; Khang, Young-Ho

    2006-11-01

    Understanding causes of hospital closure is important if hospitals are to survive and continue to fulfill their missions as the center for health care in their neighborhoods. Knowing which hospitals are most susceptible to closure can be of great use for hospital administrators and others interested in hospital performance. Although prior studies have identified a range of factors associated with increased risk of hospital closure, most are US-based and do not directly relate to health care systems in other countries. We examined determinants of hospital closure in a nationally representative sample: 805 hospitals established in South Korea before 1996 were examined-hospitals established in 1996 or after were excluded. Major organizational changes (survival vs. closure) were followed for all South Korean hospitals from 1996 through 2002. With the use of a hierarchical generalized linear model, a frailty model was used to control correlation among repeated measurements for risk factors for hospital closure. Results showed that ownership and hospital size were significantly associated with hospital closure. Urban hospitals were less likely to close than rural hospitals. However, the urban location of a hospital was not associated with hospital closure after adjustment for the proportion of elderly. Two measures for hospital competition (competitive beds and 1-Hirshman--Herfindalh index) were positively associated with risk of hospital closure before and after adjustment for confounders. In addition, annual 10% change in competitive beds was significantly predictive of hospital closure. In conclusion, yearly trends in hospital competition as well as the level of hospital competition each year affected hospital survival. Future studies need to examine the contribution of internal factors such as management strategies and financial status to hospital closure in South Korea.

  10. Assessing the Tangent Linear Behaviour of Common Tracer Transport Schemes and Their Use in a Linearised Atmospheric General Circulation Model

    NASA Technical Reports Server (NTRS)

    Holdaway, Daniel; Kent, James

    2015-01-01

    The linearity of a selection of common advection schemes is tested and examined with a view to their use in the tangent linear and adjoint versions of an atmospheric general circulation model. The schemes are tested within a simple offline one-dimensional periodic domain as well as using a simplified and complete configuration of the linearised version of NASA's Goddard Earth Observing System version 5 (GEOS-5). All schemes which prevent the development of negative values and preserve the shape of the solution are confirmed to have nonlinear behaviour. The piecewise parabolic method (PPM) with certain flux limiters, including that used by default in GEOS-5, is found to support linear growth near the shocks. This property can cause the rapid development of unrealistically large perturbations within the tangent linear and adjoint models. It is shown that these schemes with flux limiters should not be used within the linearised version of a transport scheme. The results from tests using GEOS-5 show that the current default scheme (a version of PPM) is not suitable for the tangent linear and adjoint model, and that using a linear third-order scheme for the linearised model produces better behaviour. Using the third-order scheme for the linearised model improves the correlations between the linear and non-linear perturbation trajectories for cloud liquid water and cloud liquid ice in GEOS-5.

  11. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    NASA Astrophysics Data System (ADS)

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy

  12. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

    PubMed

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-07

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy

  13. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    SciTech Connect

    Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal

    2015-04-07

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy

  14. A Community Needs Index for Adolescent Pregnancy Prevention Program Planning: Application of Spatial Generalized Linear Mixed Models.

    PubMed

    Johnson, Glen D; Mesler, Kristine; Kacica, Marilyn A

    2017-02-06

    Objective The objective is to estimate community needs with respect to risky adolescent sexual behavior in a way that is risk-adjusted for multiple community factors. Methods Generalized linear mixed modeling was applied for estimating teen pregnancy and sexually transmitted disease (STD) incidence by postal ZIP code in New York State, in a way that adjusts for other community covariables and residual spatial autocorrelation. A community needs index was then obtained by summing the risk-adjusted estimates of pregnancy and STD cases. Results Poisson regression with a spatial random effect was chosen among competing modeling approaches. Both the risk-adjusted caseloads and rates were computed for ZIP codes, which allowed risk-based prioritization to help guide funding decisions for a comprehensive adolescent pregnancy prevention program. Conclusions This approach provides quantitative evidence of community needs with respect to risky adolescent sexual behavior, while adjusting for other community-level variables and stabilizing estimates in areas with small populations. Therefore, it was well accepted by the affected groups and proved valuable for program planning. This methodology may also prove valuable for follow up program evaluation. Current research is directed towards further improving the statistical modeling approach and applying to different health and behavioral outcomes, along with different predictor variables.

  15. On the Global and Linear Convergence of the Generalized Alternating Direction Method of Multipliers

    DTIC Science & Technology

    2012-08-01

    This paper shows that global linear convergence can be guaranteed under the above assumptions on strong convexity and Lipschitz gradient on one of the...linear convergence can be guaranteed under the above assumptions on strong convexity and Lipschitz gradient on one of the two functions, along with certain...extensive literature on the ADM and its applications , there are very few results on its rate of convergence until the very recent past. Work [13] shows

  16. On the dynamics of canopy resistance: Generalized linear estimation and relationships with primary micrometeorological variables

    NASA Astrophysics Data System (ADS)

    Irmak, Suat; Mutiibwa, Denis

    2010-08-01

    The 1-D and single layer combination-based energy balance Penman-Monteith (PM) model has limitations in practical application due to the lack of canopy resistance (rc) data for different vegetation surfaces. rc could be estimated by inversion of the PM model if the actual evapotranspiration (ETa) rate is known, but this approach has its own set of issues. Instead, an empirical method of estimating rc is suggested in this study. We investigated the relationships between primary micrometeorological parameters and rc and developed seven models to estimate rc for a nonstressed maize canopy on an hourly time step using a generalized-linear modeling approach. The most complex rc model uses net radiation (Rn), air temperature (Ta), vapor pressure deficit (VPD), relative humidity (RH), wind speed at 3 m (u3), aerodynamic resistance (ra), leaf area index (LAI), and solar zenith angle (Θ). The simplest model requires Rn, Ta, and RH. We present the practical implementation of all models via experimental validation using scaled up rc data obtained from the dynamic diffusion porometer-measured leaf stomatal resistance through an extensive field campaign in 2006. For further validation, we estimated ETa by solving the PM model using the modeled rc from all seven models and compared the PM ETa estimates with the Bowen ratio energy balance system (BREBS)-measured ETa for an independent data set in 2005. The relationships between hourly rc versus Ta, RH, VPD, Rn, incoming shortwave radiation (Rs), u3, wind direction, LAI, Θ, and ra were presented and discussed. We demonstrated the negative impact of exclusion of LAI when modeling rc, whereas exclusion of ra and Θ did not impact the performance of the rc models. Compared to the calibration results, the validation root mean square difference between observed and modeled rc increased by 5 s m-1 for all rc models developed, ranging from 9.9 s m-1 for the most complex model to 22.8 s m-1 for the simplest model, as compared with the

  17. Intraoperative radiation therapy using mobile electron linear accelerators: report of AAPM Radiation Therapy Committee Task Group No. 72.

    PubMed

    Beddar, A Sam; Biggs, Peter J; Chang, Sha; Ezzell, Gary A; Faddegon, Bruce A; Hensley, Frank W; Mills, Michael D

    2006-05-01

    Intraoperative radiation therapy (IORT) has been customarily performed either in a shielded operating suite located in the operating room (OR) or in a shielded treatment room located within the Department of Radiation Oncology. In both cases, this cancer treatment modality uses stationary linear accelerators. With the development of new technology, mobile linear accelerators have recently become available for IORT. Mobility offers flexibility in treatment location and is leading to a renewed interest in IORT. These mobile accelerator units, which can be transported any day of use to almost any location within a hospital setting, are assembled in a nondedicated environment and used to deliver IORT. Numerous aspects of the design of these new units differ from that of conventional linear accelerators. The scope of this Task Group (TG-72) will focus on items that particularly apply to mobile IORT electron systems. More specifically, the charges to this Task Group are to (i) identify the key differences between stationary and mobile electron linear accelerators used for IORT, (ii) describe and recommend the implementation of an IORT program within the OR environment, (iii) present and discuss radiation protection issues and consequences of working within a nondedicated radiotherapy environment, (iv) describe and recommend the acceptance and machine commissioning of items that are specific to mobile electron linear accelerators, and (v) design and recommend an efficient quality assurance program for mobile systems.

  18. Evidence for the conjecture that sampling generalized cat states with linear optics is hard

    NASA Astrophysics Data System (ADS)

    Rohde, Peter P.; Motes, Keith R.; Knott, Paul A.; Fitzsimons, Joseph; Munro, William J.; Dowling, Jonathan P.

    2015-01-01

    Boson sampling has been presented as a simplified model for linear optical quantum computing. In the boson-sampling model, Fock states are passed through a linear optics network and sampled via number-resolved photodetection. It has been shown that this sampling problem likely cannot be efficiently classically simulated. This raises the question as to whether there are other quantum states of light for which the equivalent sampling problem is also computationally hard. We present evidence, without using a full complexity proof, that a very broad class of quantum states of light—arbitrary superpositions of two or more coherent states—when evolved via passive linear optics and sampled with number-resolved photodetection, likely implements a classically hard sampling problem.

  19. Reversibility of a quantum channel: General conditions and their applications to Bosonic linear channels

    NASA Astrophysics Data System (ADS)

    Shirokov, M. E.

    2013-11-01

    The method of complementary channel for analysis of reversibility (sufficiency) of a quantum channel with respect to families of input states (pure states for the most part) are considered and applied to Bosonic linear (quasi-free) channels, in particular, to Bosonic Gaussian channels. The obtained reversibility conditions for Bosonic linear channels have clear physical interpretation and their sufficiency is also shown by explicit construction of reversing channels. The method of complementary channel gives possibility to prove necessity of these conditions and to describe all reversed families of pure states in the Schrodinger representation. Some applications in quantum information theory are considered. Conditions for existence of discrete classical-quantum subchannels and of completely depolarizing subchannels of a Bosonic linear channel are presented.

  20. Reversibility of a quantum channel: General conditions and their applications to Bosonic linear channels

    SciTech Connect

    Shirokov, M. E.

    2013-11-15

    The method of complementary channel for analysis of reversibility (sufficiency) of a quantum channel with respect to families of input states (pure states for the most part) are considered and applied to Bosonic linear (quasi-free) channels, in particular, to Bosonic Gaussian channels. The obtained reversibility conditions for Bosonic linear channels have clear physical interpretation and their sufficiency is also shown by explicit construction of reversing channels. The method of complementary channel gives possibility to prove necessity of these conditions and to describe all reversed families of pure states in the Schrodinger representation. Some applications in quantum information theory are considered. Conditions for existence of discrete classical-quantum subchannels and of completely depolarizing subchannels of a Bosonic linear channel are presented.

  1. A generalized hybrid transfinite element computational approach for nonlinear/linear unified thermal/structural analysis

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1987-01-01

    The present paper describes the development of a new hybrid computational approach for applicability for nonlinear/linear thermal structural analysis. The proposed transfinite element approach is a hybrid scheme as it combines the modeling versatility of contemporary finite elements in conjunction with transform methods and the classical Bubnov-Galerkin schemes. Applicability of the proposed formulations for nonlinear analysis is also developed. Several test cases are presented to include nonlinear/linear unified thermal-stress and thermal-stress wave propagations. Comparative results validate the fundamental capablities of the proposed hybrid transfinite element methodology.

  2. Commentary on the statistical properties of noise and its implication on general linear models in functional near-infrared spectroscopy

    PubMed Central

    Huppert, Theodore J.

    2016-01-01

    Abstract. Functional near-infrared spectroscopy (fNIRS) is a noninvasive neuroimaging technique that uses low levels of light to measure changes in cerebral blood oxygenation levels. In the majority of NIRS functional brain studies, analysis of this data is based on a statistical comparison of hemodynamic levels between a baseline and task or between multiple task conditions by means of a linear regression model: the so-called general linear model. Although these methods are similar to their implementation in other fields, particularly for functional magnetic resonance imaging, the specific application of these methods in fNIRS research differs in several key ways related to the sources of noise and artifacts unique to fNIRS. In this brief communication, we discuss the application of linear regression models in fNIRS and the modifications needed to generalize these models in order to deal with structured (colored) noise due to systemic physiology and noise heteroscedasticity due to motion artifacts. The objective of this work is to present an overview of these noise properties in the context of the linear model as it applies to fNIRS data. This work is aimed at explaining these mathematical issues to the general fNIRS experimental researcher but is not intended to be a complete mathematical treatment of these concepts. PMID:26989756

  3. Recent advances toward a general purpose linear-scaling quantum force field.

    PubMed

    Giese, Timothy J; Huang, Ming; Chen, Haoyuan; York, Darrin M

    2014-09-16

    Conspectus There is need in the molecular simulation community to develop new quantum mechanical (QM) methods that can be routinely applied to the simulation of large molecular systems in complex, heterogeneous condensed phase environments. Although conventional methods, such as the hybrid quantum mechanical/molecular mechanical (QM/MM) method, are adequate for many problems, there remain other applications that demand a fully quantum mechanical approach. QM methods are generally required in applications that involve changes in electronic structure, such as when chemical bond formation or cleavage occurs, when molecules respond to one another through polarization or charge transfer, or when matter interacts with electromagnetic fields. A full QM treatment, rather than QM/MM, is necessary when these features present themselves over a wide spatial range that, in some cases, may span the entire system. Specific examples include the study of catalytic events that involve delocalized changes in chemical bonds, charge transfer, or extensive polarization of the macromolecular environment; drug discovery applications, where the wide range of nonstandard residues and protonation states are challenging to model with purely empirical MM force fields; and the interpretation of spectroscopic observables. Unfortunately, the enormous computational cost of conventional QM methods limit their practical application to small systems. Linear-scaling electronic structure methods (LSQMs) make possible the calculation of large systems but are still too computationally intensive to be applied with the degree of configurational sampling often required to make meaningful comparison with experiment. In this work, we present advances in the development of a quantum mechanical force field (QMFF) suitable for application to biological macromolecules and condensed phase simulations. QMFFs leverage the benefits provided by the LSQM and QM/MM approaches to produce a fully QM method that is able to

  4. Comparing Regression Coefficients between Nested Linear Models for Clustered Data with Generalized Estimating Equations

    ERIC Educational Resources Information Center

    Yan, Jun; Aseltine, Robert H., Jr.; Harel, Ofer

    2013-01-01

    Comparing regression coefficients between models when one model is nested within another is of great practical interest when two explanations of a given phenomenon are specified as linear models. The statistical problem is whether the coefficients associated with a given set of covariates change significantly when other covariates are added into…

  5. Closed and Open Systems: The Tavistock Group from a General System Perspective.

    ERIC Educational Resources Information Center

    Rugel, Robert P.

    1991-01-01

    Describes phases in the life of a Tavistock group composed of college students using concepts from Von Bertalanffy's general systems theory, MacKenzie's role theory, and Kantor's family theory. Discusses early, middle, and late phases of typical 16-session group as it moves from a closed to an open system. (Author/NB)

  6. Group versus Individual Training in Establishing Generalization of Language Skills with Severely Handicapped Individuals.

    ERIC Educational Resources Information Center

    Oliver, Peter R.; Scott, Teri L.

    1981-01-01

    Eight severely mentally handicapped adults were taught two adjective concepts--one adjective using group training and one adjective using individual instruction. Although group and individual training were equally effective in terms of rates of acquisition, generalization was 45 percent greater when exemplars of each adjective concept were taught…

  7. Two Group Development Patterns of Virtual Learning Teams: Linear Progression and Adaptive Progression

    ERIC Educational Resources Information Center

    Yoon, Seung Won

    2006-01-01

    This study examined member behaviors, distribution of performed behaviors, and development-shaping forces in order to identify group development patterns of virtual learning teams. Participants of this study were 7 newly formed virtual learning teams working on a final group project in a 12-week online graduate-level course. Examining the group…

  8. Maximum Marginal Likelihood Estimation of a Monotonic Polynomial Generalized Partial Credit Model with Applications to Multiple Group Analysis.

    PubMed

    Falk, Carl F; Cai, Li

    2016-06-01

    We present a semi-parametric approach to estimating item response functions (IRF) useful when the true IRF does not strictly follow commonly used functions. Our approach replaces the linear predictor of the generalized partial credit model with a monotonic polynomial. The model includes the regular generalized partial credit model at the lowest order polynomial. Our approach extends Liang's (A semi-parametric approach to estimate IRFs, Unpublished doctoral dissertation, 2007) method for dichotomous item responses to the case of polytomous data. Furthermore, item parameter estimation is implemented with maximum marginal likelihood using the Bock-Aitkin EM algorithm, thereby facilitating multiple group analyses useful in operational settings. Our approach is demonstrated on both educational and psychological data. We present simulation results comparing our approach to more standard IRF estimation approaches and other non-parametric and semi-parametric alternatives.

  9. Some Numerical Methods for Exponential Analysis with Connection to a General Identification Scheme for Linear Processes

    DTIC Science & Technology

    1980-11-01

    generalized nodel described by Eykhoff [1, 2], Astrom and Eykhoff [3], and on pages 209-220 of Eykhoff [4]. The origin of the general- ized model can be...aspects of process-parameter estimation," IEEE Trans. Auto. Control, October 1963, pp. 347-357. 3. K. J. Astrom and P. Eykhoff, "System

  10. Expected Estimating Equation using Calibration Data for Generalized Linear Models with a Mixture of Berkson and Classical Errors in Covariates

    PubMed Central

    de Dieu Tapsoba, Jean; Lee, Shen-Ming; Wang, Ching-Yun

    2013-01-01

    Data collected in many epidemiological or clinical research studies are often contaminated with measurement errors that may be of classical or Berkson error type. The measurement error may also be a combination of both classical and Berkson errors and failure to account for both errors could lead to unreliable inference in many situations. We consider regression analysis in generalized linear models when some covariates are prone to a mixture of Berkson and classical errors and calibration data are available only for some subjects in a subsample. We propose an expected estimating equation approach to accommodate both errors in generalized linear regression analyses. The proposed method can consistently estimate the classical and Berkson error variances based on the available data, without knowing the mixture percentage. Its finite-sample performance is investigated numerically. Our method is illustrated by an application to real data from an HIV vaccine study. PMID:24009099

  11. Nested generalized linear mixed model with ordinal response: Simulation and application on poverty data in Java Island

    NASA Astrophysics Data System (ADS)

    Widyaningsih, Yekti; Saefuddin, Asep; Notodiputro, Khairil A.; Wigena, Aji H.

    2012-05-01

    The objective of this research is to build a nested generalized linear mixed model using an ordinal response variable with some covariates. There are three main jobs in this paper, i.e. parameters estimation procedure, simulation, and implementation of the model for the real data. At the part of parameters estimation procedure, concepts of threshold, nested random effect, and computational algorithm are described. The simulations data are built for 3 conditions to know the effect of different parameter values of random effect distributions. The last job is the implementation of the model for the data about poverty in 9 districts of Java Island. The districts are Kuningan, Karawang, and Majalengka chose randomly in West Java; Temanggung, Boyolali, and Cilacap from Central Java; and Blitar, Ngawi, and Jember from East Java. The covariates in this model are province, number of bad nutrition cases, number of farmer families, and number of health personnel. In this modeling, all covariates are grouped as ordinal scale. Unit observation in this research is sub-district (kecamatan) nested in district, and districts (kabupaten) are nested in province. For the result of simulation, ARB (Absolute Relative Bias) and RRMSE (Relative Root of mean square errors) scale is used. They show that prov parameters have the highest bias, but more stable RRMSE in all conditions. The simulation design needs to be improved by adding other condition, such as higher correlation between covariates. Furthermore, as the result of the model implementation for the data, only number of farmer family and number of medical personnel have significant contributions to the level of poverty in Central Java and East Java province, and only district 2 (Karawang) of province 1 (West Java) has different random effect from the others. The source of the data is PODES (Potensi Desa) 2008 from BPS (Badan Pusat Statistik).

  12. Solution of a General Linear Complementarity Problem Using Smooth Optimization and Its Application to Bilinear Programming and LCP

    SciTech Connect

    Fernandes, L.; Friedlander, A.; Guedes, M.; Judice, J.

    2001-07-01

    This paper addresses a General Linear Complementarity Problem (GLCP) that has found applications in global optimization. It is shown that a solution of the GLCP can be computed by finding a stationary point of a differentiable function over a set defined by simple bounds on the variables. The application of this result to the solution of bilinear programs and LCPs is discussed. Some computational evidence of its usefulness is included in the last part of the paper.

  13. General relation between the group delay and dwell time in multicomponent electron systems

    NASA Astrophysics Data System (ADS)

    Zhai, Feng; Lu, Junqiang

    2016-10-01

    For multicomponent electron scattering states, we derive a general relation between the Wigner group delay and the Bohmian dwell time. It is found that the definition of group delay should account for the phase of the spinor wave functions of propagating modes. The difference between the group delay and dwell time comes from both the interference delay and the decaying modes. For barrier tunneling of helical electrons on a surface of topological insulators, our calculations including the trigonal-warping term show that the decaying modes can contribute greatly to the group delay. The derived relation between the group delay and the dwell time is helpful to unify the two definitions of tunneling time in a quite general situation.

  14. Principal components and generalized linear modeling in the correlation between hospital admissions and air pollution

    PubMed Central

    de Souza, Juliana Bottoni; Reisen, Valdério Anselmo; Santos, Jane Méri; Franco, Glaura Conceição

    2014-01-01

    OBJECTIVE To analyze the association between concentrations of air pollutants and admissions for respiratory causes in children. METHODS Ecological time series study. Daily figures for hospital admissions of children aged < 6, and daily concentrations of air pollutants (PM10, SO2, NO2, O3 and CO) were analyzed in the Região da Grande Vitória, ES, Southeastern Brazil, from January 2005 to December 2010. For statistical analysis, two techniques were combined: Poisson regression with generalized additive models and principal model component analysis. Those analysis techniques complemented each other and provided more significant estimates in the estimation of relative risk. The models were adjusted for temporal trend, seasonality, day of the week, meteorological factors and autocorrelation. In the final adjustment of the model, it was necessary to include models of the Autoregressive Moving Average Models (p, q) type in the residuals in order to eliminate the autocorrelation structures present in the components. RESULTS For every 10:49 μg/m3 increase (interquartile range) in levels of the pollutant PM10 there was a 3.0% increase in the relative risk estimated using the generalized additive model analysis of main components-seasonal autoregressive – while in the usual generalized additive model, the estimate was 2.0%. CONCLUSIONS Compared to the usual generalized additive model, in general, the proposed aspect of generalized additive model − principal component analysis, showed better results in estimating relative risk and quality of fit. PMID:25119940

  15. Antitumor activities and interaction with DNA of oxaliplatin-type platinum complexes with linear or branched alkoxyacetates as leaving groups.

    PubMed

    Yin, Runting; Gou, Shaohua; Liu, Xia; Lou, Liguang

    2011-08-01

    Five oxaliplatin-typed platinum complexes containing trans-1R, 2R-diaminocyclohexane chelating platinum cores, characteristic of linear or branched alkoxycarboxylates as leaving groups, were biologically evaluated. These compounds showed higher antitumor activity, lower toxicity in vivo than cisplatin or oxaliplatin. And the results revealed that the antitumor activity and interaction with DNA of these compounds were highly related to the nature of leaving groups. Among these complexes, 5a, cis-(trans-1R, 2R-diaminocyclohexane) bis (2-tert-butoxyacetate) platinum(II), showed the highest antitumor activity and the lowest toxicity.

  16. A general algorithm for control problems with variable parameters and quasi-linear models

    NASA Astrophysics Data System (ADS)

    Bayón, L.; Grau, J. M.; Ruiz, M. M.; Suárez, P. M.

    2015-12-01

    This paper presents an algorithm that is able to solve optimal control problems in which the modelling of the system contains variable parameters, with the added complication that, in certain cases, these parameters can lead to control problems governed by quasi-linear equations. Combining the techniques of Pontryagin's Maximum Principle and the shooting method, an algorithm has been developed that is not affected by the values of the parameters, being able to solve conventional problems as well as cases in which the optimal solution is shown to be bang-bang with singular arcs.

  17. Identification of general linear relationships between activation energies and enthalpy changes for dissociation reactions at surfaces.

    PubMed

    Michaelides, Angelos; Liu, Z-P; Zhang, C J; Alavi, Ali; King, David A; Hu, P

    2003-04-02

    The activation energy to reaction is a key quantity that controls catalytic activity. Having used ab inito calculations to determine an extensive and broad ranging set of activation energies and enthalpy changes for surface-catalyzed reactions, we show that linear relationships exist between dissociation activation energies and enthalpy changes. Known in the literature as empirical Brønsted-Evans-Polanyi (BEP) relationships, we identify and discuss the physical origin of their presence in heterogeneous catalysis. The key implication is that merely from knowledge of adsorption energies the barriers to catalytic elementary reaction steps can be estimated.

  18. A substructure coupling procedure applicable to general linear time-invariant dynamic systems

    NASA Technical Reports Server (NTRS)

    Howsman, T. G.; Craig, R. R., Jr.

    1984-01-01

    A substructure synthesis procedure applicable to structural systems containing general nonconservative terms is presented. In their final form, the nonself-adjoint substructure equations of motion are cast in state vector form through the use of a variational principle. A reduced-order mode for each substructure is implemented by representing the substructure as a combination of a small number of Ritz vectors. For the method presented, the substructure Ritz vectors are identified as a truncated set of substructure eigenmodes, which are typically complex, along with a set of generalized real attachment modes. The formation of the generalized attachment modes does not require any knowledge of the substructure flexible modes; hence, only the eigenmodes used explicitly as Ritz vectors need to be extracted from the substructure eigenproblem. An example problem is presented to illustrate the method.

  19. Optimization of biochemical systems by linear programming and general mass action model representations.

    PubMed

    Marín-Sanguino, Alberto; Torres, Néstor V

    2003-08-01

    A new method is proposed for the optimization of biochemical systems. The method, based on the separation of the stoichiometric and kinetic aspects of the system, follows the general approach used in the previously presented indirect optimization method (IOM) developed within biochemical systems theory. It is called GMA-IOM because it makes use of the generalized mass action (GMA) as the model system representation form. The GMA representation avoids flux aggregation and thus prevents possible stoichiometric errors. The optimization of a system is used to illustrate and compare the features, advantages and shortcomings of both versions of the IOM method as a general strategy for designing improved microbial strains of biotechnological interest. Special attention has been paid to practical problems for the actual implementation of the new proposed strategy, such as the total protein content of the engineered strain or the deviation from the original steady state and its influence on cell viability.

  20. General theory of spherically symmetric boundary-value problems of the linear transport theory.

    NASA Technical Reports Server (NTRS)

    Kanal, M.

    1972-01-01

    A general theory of spherically symmetric boundary-value problems of the one-speed neutron transport theory is presented. The formulation is also applicable to the 'gray' problems of radiative transfer. The Green's function for the purely absorbing medium is utilized in obtaining the normal mode expansion of the angular densities for both interior and exterior problems. As the integral equations for unknown coefficients are regular, a general class of reduction operators is introduced to reduce such regular integral equations to singular ones with a Cauchy-type kernel. Such operators then permit one to solve the singular integral equations by the standard techniques due to Muskhelishvili. We discuss several spherically symmetric problems. However, the treatment is kept sufficiently general to deal with problems lacking azimuthal symmetry. In particular the procedure seems to work for regions whose boundary coincides with one of the coordinate surfaces for which the Helmholtz equation is separable.

  1. The Exact Solution for Linear Thermoelastic Axisymmetric Deformations of Generally Laminated Circular Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.; Schultz, Marc R.

    2012-01-01

    A detailed exact solution is presented for laminated-composite circular cylinders with general wall construction and that undergo axisymmetric deformations. The overall solution is formulated in a general, systematic way and is based on the solution of a single fourth-order, nonhomogeneous ordinary differential equation with constant coefficients in which the radial displacement is the dependent variable. Moreover, the effects of general anisotropy are included and positive-definiteness of the strain energy is used to define uniquely the form of the basis functions spanning the solution space of the ordinary differential equation. Loading conditions are considered that include axisymmetric edge loads, surface tractions, and temperature fields. Likewise, all possible axisymmetric boundary conditions are considered. Results are presented for five examples that demonstrate a wide range of behavior for specially orthotropic and fully anisotropic cylinders.

  2. Building functional groups of marine benthic macroinvertebrates on the basis of general community assembly mechanisms

    NASA Astrophysics Data System (ADS)

    Alexandridis, Nikolaos; Bacher, Cédric; Desroy, Nicolas; Jean, Fred

    2017-03-01

    The accurate reproduction of the spatial and temporal dynamics of marine benthic biodiversity requires the development of mechanistic models, based on the processes that shape macroinvertebrate communities. The modelled entities should, accordingly, be able to adequately represent the many functional roles that are performed by benthic organisms. With this goal in mind, we applied the emergent group hypothesis (EGH), which assumes functional equivalence within and functional divergence between groups of species. The first step of the grouping involved the selection of 14 biological traits that describe the role of benthic macroinvertebrates in 7 important community assembly mechanisms. A matrix of trait values for the 240 species that occurred in the Rance estuary (Brittany, France) in 1995 formed the basis for a hierarchical classification that generated 20 functional groups, each with its own trait values. The functional groups were first evaluated based on their ability to represent observed patterns of biodiversity. The two main assumptions of the EGH were then tested, by assessing the preservation of niche attributes among the groups and the neutrality of functional differences within them. The generally positive results give us confidence in the ability of the grouping to recreate functional diversity in the Rance estuary. A first look at the emergent groups provides insights into the potential role of community assembly mechanisms in shaping biodiversity patterns. Our next steps include the derivation of general rules of interaction and their incorporation, along with the functional groups, into mechanistic models of benthic biodiversity.

  3. Interaction between participants in focus groups with older patients and general practitioners.

    PubMed

    Moen, Janne; Antonov, Karolina; Nilsson, J Lars G; Ring, Lena

    2010-05-01

    Group interaction is put forward as the principal advantage for focus group research, although rarely reported on. The aim of the article is to contribute to the methodological knowledge regarding focus group research by providing an empirical example of the application of the Lehoux, Poland, and Daudelin template suggested for analysis of the interaction in focus groups. The data source was 18 focus groups' performance in Sweden: 12 with older patients and 6 with general practitioners (GPs). GPs found common ground in belonging to the same profession, whereas the older patients, instead of constituting a group in the word's real sense, started just sharing a common focus. We found the template easy to understand and use, except for identifying participants' explicit and implicit purposes for participating. Furthermore, adding an interaction analysis to the content analysis helped us appreciate and clarify the contexts from which these data were created.

  4. Robust conic generalized partial linear models using RCMARS method - A robustification of CGPLM

    NASA Astrophysics Data System (ADS)

    Özmen, Ayşe; Weber, Gerhard Wilhelm

    2012-11-01

    GPLM is a combination of two different regression models each of which is used to apply on different parts of the data set. It is also adequate to high dimensional, non-normal and nonlinear data sets having the flexibility to reflect all anomalies effectively. In our previous study, Conic GPLM (CGPLM) was introduced using CMARS and Logistic Regression. According to a comparison with CMARS, CGPLM gives better results. In this study, we include the existence of uncertainty in the future scenarios into CMARS and linear/logit regression part in CGPLM and robustify it with robust optimization which is dealt with data uncertainty. Moreover, we apply RCGPLM on a small data set as a numerical experience from the financial sector.

  5. Iterative solution of general sparse linear systems on clusters of workstations

    SciTech Connect

    Lo, Gen-Ching; Saad, Y.

    1996-12-31

    Solving sparse irregularly structured linear systems on parallel platforms poses several challenges. First, sparsity makes it difficult to exploit data locality, whether in a distributed or shared memory environment. A second, perhaps more serious challenge, is to find efficient ways to precondition the system. Preconditioning techniques which have a large degree of parallelism, such as multicolor SSOR, often have a slower rate of convergence than their sequential counterparts. Finally, a number of other computational kernels such as inner products could ruin any gains gained from parallel speed-ups, and this is especially true on workstation clusters where start-up times may be high. In this paper we discuss these issues and report on our experience with PSPARSLIB, an on-going project for building a library of parallel iterative sparse matrix solvers.

  6. Quasi-Linear Parameter Varying Representation of General Aircraft Dynamics Over Non-Trim Region

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob

    2007-01-01

    For applying linear parameter varying (LPV) control synthesis and analysis to a nonlinear system, it is required that a nonlinear system be represented in the form of an LPV model. In this paper, a new representation method is developed to construct an LPV model from a nonlinear mathematical model without the restriction that an operating point must be in the neighborhood of equilibrium points. An LPV model constructed by the new method preserves local stabilities of the original nonlinear system at "frozen" scheduling parameters and also represents the original nonlinear dynamics of a system over a non-trim region. An LPV model of the motion of FASER (Free-flying Aircraft for Subscale Experimental Research) is constructed by the new method.

  7. Linear stability of plane Poiseuille flow over a generalized Stokes layer

    NASA Astrophysics Data System (ADS)

    Quadrio, Maurizio; Martinelli, Fulvio; Schmid, Peter J.

    2011-12-01

    Linear stability of plane Poiseuille flow subject to spanwise velocity forcing applied at the wall is studied. The forcing is stationary and sinusoidally distributed along the streamwise direction. The long-term aim of the study is to explore a possible relationship between the modification induced by the wall forcing to the stability characteristic of the unforced Poiseuille flow and the signifcant capabilities demonstrated by the same forcing in reducing turbulent friction drag. We present in this paper the statement of the mathematical problem, which is considerably more complex that the classic Orr-Sommerfeld-Squire approach, owing to the streamwise-varying boundary condition. We also report some preliminary results which, although not yet conclusive, describe the effects of the wall forcing on modal and non-modal characteristics of the flow stability.

  8. Generalization of the tensor renormalization group approach to 3-D or higher dimensions

    NASA Astrophysics Data System (ADS)

    Teng, Peiyuan

    2017-04-01

    In this paper, a way of generalizing the tensor renormalization group (TRG) is proposed. Mathematically, the connection between patterns of tensor renormalization group and the concept of truncation sequence in polytope geometry is discovered. A theoretical contraction framework is therefore proposed. Furthermore, the canonical polyadic decomposition is introduced to tensor network theory. A numerical verification of this method on the 3-D Ising model is carried out.

  9. FIDDLE: A Computer Code for Finite Difference Development of Linear Elasticity in Generalized Curvilinear Coordinates

    NASA Technical Reports Server (NTRS)

    Kaul, Upender K.

    2005-01-01

    A three-dimensional numerical solver based on finite-difference solution of three-dimensional elastodynamic equations in generalized curvilinear coordinates has been developed and used to generate data such as radial and tangential stresses over various gear component geometries under rotation. The geometries considered are an annulus, a thin annular disk, and a thin solid disk. The solution is based on first principles and does not involve lumped parameter or distributed parameter systems approach. The elastodynamic equations in the velocity-stress formulation that are considered here have been used in the solution of problems of geophysics where non-rotating Cartesian grids are considered. For arbitrary geometries, these equations along with the appropriate boundary conditions have been cast in generalized curvilinear coordinates in the present study.

  10. Teaching Is Learning--Maximum Incentive, Minimum Discipline in Student Groups Teaching General Chemistry

    NASA Astrophysics Data System (ADS)

    Benvenuto, Mark

    2001-02-01

    A novel form of teaching and test scoring has been developed, in which student group work and test performance are linked to bonus points on weekly quizzes. A class of 71 students was divided into 12 groups of five or six students. The groups taught sections of a general chemistry class, and their test grades were adjusted upward on the basis of the scores achieved for each quiz or test. The scoring technique involves the possibility of only upward adjustments, to maximize positive reinforcement for good test performance. Work requirements resulting from this technique, for both the students and the faculty member, are discussed.

  11. Small Group Instruction for Students with Autism: General Case Training and Observational Learning

    ERIC Educational Resources Information Center

    Tekin-Iftar, Elif; Birkan, Bunyamin

    2010-01-01

    A multiple-probe design across response chains and students was used to evaluate the combined instructional effects of progressive time delay, general case training, and observational learning on the food and drink preparation skills of three children with autism. All instruction was delivered in a group learning arrangement. The data suggested…

  12. CONSTRUCTION OF A GENERAL GROUP TEST FOR PUERTO RICAN STUDENTS IN THE ELEMENTARY AND SECONDARY SCHOOLS.

    ERIC Educational Resources Information Center

    ROCA, PABLO

    THIS STUDY ATTEMPTED TO DEVELOP A GROUP TEST OF GENERAL ABILITY WHICH WILL ACCURATELY ASSESS THE INTELLECTUAL CAPACITIES OF ELEMENTARY AND SECONDARY STUDENTS IN THE PUERTO RICAN SCHOOLS. THE OBJECTIVES WERE--(1) TO DETERMINE WHAT COMMON INTELLECTUAL TASKS INDICATE MENTAL ABILITY IN SPANISH-SPEAKING PUERTO RICAN AND OTHER ENGLISH-SPEAKING AMERICAN…

  13. Modeling Differential Item Functioning Using a Generalization of the Multiple-Group Bifactor Model

    ERIC Educational Resources Information Center

    Jeon, Minjeong; Rijmen, Frank; Rabe-Hesketh, Sophia

    2013-01-01

    The authors present a generalization of the multiple-group bifactor model that extends the classical bifactor model for categorical outcomes by relaxing the typical assumption of independence of the specific dimensions. In addition to the means and variances of all dimensions, the correlations among the specific dimensions are allowed to differ…

  14. Promoting Student Learning through Group Problem Solving in General Chemistry Recitations

    ERIC Educational Resources Information Center

    Mahalingam, Madhu; Schaefer, Fred; Morlino, Elisabeth

    2008-01-01

    We describe the implementation and effects of group problem solving in recitation sections associated with the general chemistry course at a small private science university. Recitation sections of approximately 45 students are used to supplement large (approximately 180 students) lecture sections. The primary goal of recitation is working in…

  15. Learning-Related Behaviors: Small Group Reading Instruction in the General Education Classroom

    ERIC Educational Resources Information Center

    Weiss, Stacy L.

    2013-01-01

    Supplemental small group reading instruction is frequently provided in the general education setting to struggling students at elementary schools that use response to intervention frameworks. Although building reading proficiency is the main focus of the intervention, students' learning-related behaviors should also be addressed to improve…

  16. A novel synchronization scheme with a simple linear control and guaranteed convergence time for generalized Lorenz chaotic systems.

    PubMed

    Chuang, Chun-Fu; Sun, Yeong-Jeu; Wang, Wen-June

    2012-12-01

    In this study, exponential finite-time synchronization for generalized Lorenz chaotic systems is investigated. The significant contribution of this paper is that master-slave synchronization is achieved within a pre-specified convergence time and with a simple linear control. The designed linear control consists of two parts: one achieves exponential synchronization, and the other realizes finite-time synchronization within a guaranteed convergence time. Furthermore, the control gain depends on the parameters of the exponential convergence rate, the finite-time convergence rate, the bound of the initial states of the master system, and the system parameter. In addition, the proposed approach can be directly and efficiently applied to secure communication. Finally, four numerical examples are provided to demonstrate the feasibility and correctness of the obtained results.

  17. A generalized Lyapunov theory for robust root clustering of linear state space models with real parameter uncertainty

    NASA Technical Reports Server (NTRS)

    Yedavalli, R. K.

    1992-01-01

    The problem of analyzing and designing controllers for linear systems subject to real parameter uncertainty is considered. An elegant, unified theory for robust eigenvalue placement is presented for a class of D-regions defined by algebraic inequalities by extending the nominal matrix root clustering theory of Gutman and Jury (1981) to linear uncertain time systems. The author presents explicit conditions for matrix root clustering for different D-regions and establishes the relationship between the eigenvalue migration range and the parameter range. The bounds are all obtained by one-shot computation in the matrix domain and do not need any frequency sweeping or parameter gridding. The method uses the generalized Lyapunov theory for getting the bounds.

  18. Providing mentorship support to general surgery residents: a model for structured group facilitation

    PubMed Central

    Champion, Caitlin; Bennett, Sean; Carver, David; El Tawil, Karim; Fabbro, Sarah; Howatt, Neil; Noei, Farahnaz; Rae, Rachel; Haggar, Fatima; Arnaout, Angel

    2015-01-01

    Summary Mentorship is foundational to surgical training, with recognized benefits for both mentees and mentors. The University of Ottawa General Surgery Mentorship Program was developed as a module-based group facilitation program to support inclusive personal and professional development of junior general surgery residents. The group format provided an opportunity for both vertical and horizontal mentorship relationships between staff mentors and resident mentees. Perceived benefits of program participants were evaluated at the conclusion of the first year of the program. The program was well-received by staff and resident participants and may provide a time-efficient and inclusive mentorship structure with the additional benefit of peer support. We review the development and implementation of the program to date and share our mentorship experience to encourage the growth of formal mentorship opportunities within general surgery training programs. PMID:26424687

  19. Classical and Generalized Solutions of Time-Dependent Linear Differential Algebraic Equations

    DTIC Science & Technology

    1993-10-15

    matrix pencils, [G59]. The book [GrM86] also contains a treatment of the general system (1.1) utilizing a condition of "transferabilitv’" which...C(t) and N(t) are analytic functions of t and N(t) is nilpotent upper (or lower) triangular for all t E J. From the structure of N(t), it follows that...the operator Y(t)l7 n is nilpotent , so that (1.2b) has the unique solution z = E (-1)k(N(t)-)kg, and (1.2a) is k=1 it an explicit ODE. But no

  20. Incorporating cancer risk information into general practice: a qualitative study using focus groups with health professionals

    PubMed Central

    Usher-Smith, Juliet A; Silarova, Barbora; Ward, Alison; Youell, Jane; Muir, Kenneth R; Campbell, Jackie; Warcaba, Joanne

    2017-01-01

    Background It is estimated that approximately 40% of all cases of cancer are attributable to lifestyle factors. Providing people with personalised information about their future risk of cancer may help promote behaviour change. Aim To explore the views of health professionals on incorporating personalised cancer risk information, based on lifestyle factors, into general practice. Design and setting Qualitative study using data from six focus groups with a total of 24 general practice health professionals from the NHS Nene Clinical Commissioning Group in England. Method The focus groups were guided by a schedule covering current provision of lifestyle advice relating to cancer and views on incorporating personalised cancer risk information. Data were audiotaped, transcribed verbatim, and then analysed using thematic analysis. Results Providing lifestyle advice was viewed as a core activity within general practice but the influence of lifestyle on cancer risk was rarely discussed. The word ‘cancer’ was seen as a potentially powerful motivator for lifestyle change but the fact that it could generate health anxiety was also recognised. Most focus group participants felt that a numerical risk estimate was more likely to influence behaviour than generic advice. All felt that general practice should provide this information, but there was a clear need for additional resources for it to be offered widely. Conclusion Study participants were in support of providing personalised cancer risk information in general practice. The findings highlight a number of potential benefits and challenges that will inform the future development of interventions in general practice to promote behaviour change for cancer prevention. PMID:28193618

  1. The general Lie group and similarity solutions for the one-dimensional Vlasov-Maxwell equations

    NASA Technical Reports Server (NTRS)

    Roberts, D.

    1985-01-01

    The general Lie point transformation group and the associated reduced differential equations and similarity forms for the solutions are derived here for the coupled (nonlinear) Vlasov-Maxwell equations in one spatial dimension. The case of one species in a background is shown to admit a larger group than the multispecies case. Previous exact solutions are shown to be special cases of the above solutions, and many of the new solutions are found to constrain the form of the distribution function much more than, for example, the BGK solutions do. The individual generators of the Lie group are used to find the possible subgroups. Finally, a simple physical argument is given to show that the asymptotic solution for a one-species, one-dimensional plasma is one of the general similarity solutions.

  2. Generalization of verbal conditioning to verbal and nonverbal behavior: group therapy with chronic psychiatric patients1

    PubMed Central

    Tracey, Dorothy A.; Briddell, Dan W.; Wilson, G. Terence

    1974-01-01

    Twelve chronic hospitalized female patients received token reinforcement contingent on two separate classes of verbalizations: (a) positive statements about optional activities available in the hospital setting, and (b) positive statements about people. Cross-class generalization of reinforced verbal responses about activities to overt behavior was tested by actual participation in activities; within-class generalization of verbal responses about people to verbalizations in another stimulus setting was assessed in a structured interview situation. A multiple baseline design with contingency reversals was employed to demonstrate experimental control of both classes of verbalizations in the group sessions. Positive statements about activities generalized to actual participation in activities, while generalization of positive statements about people to verbalization in the extragroup setting did not occur. PMID:4465377

  3. A computer program for the generalized chi-square analysis of competing risks grouped survival data (CRISCAT).

    PubMed

    Stanish, W M; Chi, G Y; Johnson, W D; Koch, G G; Landis, J R; Liu-Chi, S

    1978-09-01

    CRISCAT is a computer program for the analysis of grouped survival data with competing risks via weighted least squares methods. Competing risks adjustments are obtained from general matrix operations using many of the strategies employed in a previously developed program (GENCAT) for multivariate categorical data. CRISCAT computes survival rates at several time points for multiple causes of failure, where each rate is adjusted for other causes in the sense that failure due to thes other causes has been eliminated as a risk. The program can generate functions of the adjusted survival rates, to which asymptotic regression models may be fit. CRISCAT yields test statistics for hypotheses involving either these functions or estimated model parameters. Thus, this computational algorithm links competing risks theory to linear models methods for contingency table analysis and provides a unified approach to estimation and hypothesis testing of functions involving competing risks adjusted rates.

  4. Methodological Quality and Reporting of Generalized Linear Mixed Models in Clinical Medicine (2000–2012): A Systematic Review

    PubMed Central

    Casals, Martí; Girabent-Farrés, Montserrat; Carrasco, Josep L.

    2014-01-01

    Background Modeling count and binary data collected in hierarchical designs have increased the use of Generalized Linear Mixed Models (GLMMs) in medicine. This article presents a systematic review of the application and quality of results and information reported from GLMMs in the field of clinical medicine. Methods A search using the Web of Science database was performed for published original articles in medical journals from 2000 to 2012. The search strategy included the topic “generalized linear mixed models”,“hierarchical generalized linear models”, “multilevel generalized linear model” and as a research domain we refined by science technology. Papers reporting methodological considerations without application, and those that were not involved in clinical medicine or written in English were excluded. Results A total of 443 articles were detected, with an increase over time in the number of articles. In total, 108 articles fit the inclusion criteria. Of these, 54.6% were declared to be longitudinal studies, whereas 58.3% and 26.9% were defined as repeated measurements and multilevel design, respectively. Twenty-two articles belonged to environmental and occupational public health, 10 articles to clinical neurology, 8 to oncology, and 7 to infectious diseases and pediatrics. The distribution of the response variable was reported in 88% of the articles, predominantly Binomial (n = 64) or Poisson (n = 22). Most of the useful information about GLMMs was not reported in most cases. Variance estimates of random effects were described in only 8 articles (9.2%). The model validation, the method of covariate selection and the method of goodness of fit were only reported in 8.0%, 36.8% and 14.9% of the articles, respectively. Conclusions During recent years, the use of GLMMs in medical literature has increased to take into account the correlation of data when modeling qualitative data or counts. According to the current recommendations, the quality of

  5. The Influences of Group and Independent General Practice on Patient Care

    PubMed Central

    Sellers, E. M.

    1965-01-01

    When the practices of four general practitioners, members of multispecialist-general practitioner salaried groups (clinic doctors) were compared with those of four independent general practitioners (solo practitioners), it was noted that: group practice patients had more office laboratory investigation and greater in-hospital consultation and referral. On the other hand, independent practitioners' patients seemed to receive more personal attention from the doctor, a fuller explanation of diagnosis and treatment during office hours, more drug samples and more laboratory investigation in hospital. Group and independent practices are similar with respect to the rate of follow-up visits, the volume of preventive medicine, the number of radiographs and special procedures, the total number of drugs ordered, and the in-hospital formal written consultation rate and office consultation rate. The similarities between two types of practice may be a result of the interaction of group and independent practice in the same community. It is concluded that the team approach to medical care is not incompatible with independent practice. PMID:14323656

  6. Balint Groups as a Means to Increase Job Satisfaction and Prevent Burnout Among General Practitioners

    PubMed Central

    Kjeldmand, Dorte; Holmström, Inger

    2008-01-01

    PURPOSE General practitioners (GPs) occupy a central position in health care and often have demanding working situations. This corps shows signs of exhaustion, and many consider quitting their job or plan to retire early. It is therefore urgent to find ways of improving GP’s satisfaction with their work. One approach might be Balint group participation. The aim of this study was to explore GPs’ experience of participating in Balint groups and its influence on their work life. METHODS We conducted a descriptive, qualitative study. Nine GPs who had participated in Balint groups for 3 to 15 years were interviewed. A phenomenologic analysis was carried out to describe the phenomenon of Balint group participation. RESULTS The GPs perceived that their Balint group participation influenced their work life. Analyses revealed several interrelating themes: competence, professional identity, and a sense of security, which increased through parallel processes, creating a base of endurance and satisfaction, thus enabling the GPs to rediscover the joy of being a physician. CONCLUSIONS The GPs in this study described their Balint group participation as beneficial and essential to their work life as physicians in several ways. It seemed to increase their competence in patient encounters and enabled them to endure in their job and find joy and challenge in their relationships with patients. Balint groups might thus help GPs handle a demanding work life and prevent burnout. These groups might not suit all GPs, however, and additional ways to reduce stress and increase job satisfaction should be offered. PMID:18332406

  7. FUSED KERNEL-SPLINE SMOOTHING FOR REPEATEDLY MEASURED OUTCOMES IN A GENERALIZED PARTIALLY LINEAR MODEL WITH FUNCTIONAL SINGLE INDEX*

    PubMed Central

    Jiang, Fei; Ma, Yanyuan; Wang, Yuanjia

    2015-01-01

    We propose a generalized partially linear functional single index risk score model for repeatedly measured outcomes where the index itself is a function of time. We fuse the nonparametric kernel method and regression spline method, and modify the generalized estimating equation to facilitate estimation and inference. We use local smoothing kernel to estimate the unspecified coefficient functions of time, and use B-splines to estimate the unspecified function of the single index component. The covariance structure is taken into account via a working model, which provides valid estimation and inference procedure whether or not it captures the true covariance. The estimation method is applicable to both continuous and discrete outcomes. We derive large sample properties of the estimation procedure and show different convergence rate of each component of the model. The asymptotic properties when the kernel and regression spline methods are combined in a nested fashion has not been studied prior to this work even in the independent data case. PMID:26283801

  8. FUSED KERNEL-SPLINE SMOOTHING FOR REPEATEDLY MEASURED OUTCOMES IN A GENERALIZED PARTIALLY LINEAR MODEL WITH FUNCTIONAL SINGLE INDEX.

    PubMed

    Jiang, Fei; Ma, Yanyuan; Wang, Yuanjia

    We propose a generalized partially linear functional single index risk score model for repeatedly measured outcomes where the index itself is a function of time. We fuse the nonparametric kernel method and regression spline method, and modify the generalized estimating equation to facilitate estimation and inference. We use local smoothing kernel to estimate the unspecified coefficient functions of time, and use B-splines to estimate the unspecified function of the single index component. The covariance structure is taken into account via a working model, which provides valid estimation and inference procedure whether or not it captures the true covariance. The estimation method is applicable to both continuous and discrete outcomes. We derive large sample properties of the estimation procedure and show different convergence rate of each component of the model. The asymptotic properties when the kernel and regression spline methods are combined in a nested fashion has not been studied prior to this work even in the independent data case.

  9. Biohybrid Control of General Linear Systems Using the Adaptive Filter Model of Cerebellum

    PubMed Central

    Wilson, Emma D.; Assaf, Tareq; Pearson, Martin J.; Rossiter, Jonathan M.; Dean, Paul; Anderson, Sean R.; Porrill, John

    2015-01-01

    The adaptive filter model of the cerebellar microcircuit has been successfully applied to biological motor control problems, such as the vestibulo-ocular reflex (VOR), and to sensory processing problems, such as the adaptive cancelation of reafferent noise. It has also been successfully applied to problems in robotics, such as adaptive camera stabilization and sensor noise cancelation. In previous applications to inverse control problems, the algorithm was applied to the velocity control of a plant dominated by viscous and elastic elements. Naive application of the adaptive filter model to the displacement (as opposed to velocity) control of this plant results in unstable learning and control. To be more generally useful in engineering problems, it is essential to remove this restriction to enable the stable control of plants of any order. We address this problem here by developing a biohybrid model reference adaptive control (MRAC) scheme, which stabilizes the control algorithm for strictly proper plants. We evaluate the performance of this novel cerebellar-inspired algorithm with MRAC scheme in the experimental control of a dielectric electroactive polymer, a class of artificial muscle. The results show that the augmented cerebellar algorithm is able to accurately control the displacement response of the artificial muscle. The proposed solution not only greatly extends the practical applicability of the cerebellar-inspired algorithm, but may also shed light on cerebellar involvement in a wider range of biological control tasks. PMID:26257638

  10. Biohybrid Control of General Linear Systems Using the Adaptive Filter Model of Cerebellum.

    PubMed

    Wilson, Emma D; Assaf, Tareq; Pearson, Martin J; Rossiter, Jonathan M; Dean, Paul; Anderson, Sean R; Porrill, John

    2015-01-01

    The adaptive filter model of the cerebellar microcircuit has been successfully applied to biological motor control problems, such as the vestibulo-ocular reflex (VOR), and to sensory processing problems, such as the adaptive cancelation of reafferent noise. It has also been successfully applied to problems in robotics, such as adaptive camera stabilization and sensor noise cancelation. In previous applications to inverse control problems, the algorithm was applied to the velocity control of a plant dominated by viscous and elastic elements. Naive application of the adaptive filter model to the displacement (as opposed to velocity) control of this plant results in unstable learning and control. To be more generally useful in engineering problems, it is essential to remove this restriction to enable the stable control of plants of any order. We address this problem here by developing a biohybrid model reference adaptive control (MRAC) scheme, which stabilizes the control algorithm for strictly proper plants. We evaluate the performance of this novel cerebellar-inspired algorithm with MRAC scheme in the experimental control of a dielectric electroactive polymer, a class of artificial muscle. The results show that the augmented cerebellar algorithm is able to accurately control the displacement response of the artificial muscle. The proposed solution not only greatly extends the practical applicability of the cerebellar-inspired algorithm, but may also shed light on cerebellar involvement in a wider range of biological control tasks.

  11. Generalized Uncertainty Quantification for Linear Inverse Problems in X-ray Imaging

    SciTech Connect

    Fowler, Michael James

    2014-04-25

    In industrial and engineering applications, X-ray radiography has attained wide use as a data collection protocol for the assessment of material properties in cases where direct observation is not possible. The direct measurement of nuclear materials, particularly when they are under explosive or implosive loading, is not feasible, and radiography can serve as a useful tool for obtaining indirect measurements. In such experiments, high energy X-rays are pulsed through a scene containing material of interest, and a detector records a radiograph by measuring the radiation that is not attenuated in the scene. One approach to the analysis of these radiographs is to model the imaging system as an operator that acts upon the object being imaged to produce a radiograph. In this model, the goal is to solve an inverse problem to reconstruct the values of interest in the object, which are typically material properties such as density or areal density. The primary objective in this work is to provide quantitative solutions with uncertainty estimates for three separate applications in X-ray radiography: deconvolution, Abel inversion, and radiation spot shape reconstruction. For each problem, we introduce a new hierarchical Bayesian model for determining a posterior distribution on the unknowns and develop efficient Markov chain Monte Carlo (MCMC) methods for sampling from the posterior. A Poisson likelihood, based on a noise model for photon counts at the detector, is combined with a prior tailored to each application: an edge-localizing prior for deconvolution; a smoothing prior with non-negativity constraints for spot reconstruction; and a full covariance sampling prior based on a Wishart hyperprior for Abel inversion. After developing our methods in a general setting, we demonstrate each model on both synthetically generated datasets, including those from a well known radiation transport code, and real high energy radiographs taken at two U. S. Department of Energy

  12. The generalized cross-validation method applied to geophysical linear traveltime tomography

    NASA Astrophysics Data System (ADS)

    Bassrei, A.; Oliveira, N. P.

    2009-12-01

    The oil industry is the major user of Applied Geophysics methods for the subsurface imaging. Among different methods, the so-called seismic (or exploration seismology) methods are the most important. Tomography was originally developed for medical imaging and was introduced in exploration seismology in the 1980's. There are two main classes of geophysical tomography: those that use only the traveltimes between sources and receivers, which is a cinematic approach and those that use the wave amplitude itself, being a dynamic approach. Tomography is a kind of inverse problem, and since inverse problems are usually ill-posed, it is necessary to use some method to reduce their deficiencies. These difficulties of the inverse procedure are associated with the fact that the involved matrix is ill-conditioned. To compensate this shortcoming, it is appropriate to use some technique of regularization. In this work we make use of regularization with derivative matrices, also called smoothing. There is a crucial problem in regularization, which is the selection of the regularization parameter lambda. We use generalized cross validation (GCV) as a tool for the selection of lambda. GCV chooses the regularization parameter associated with the best average prediction for all possible omissions of one datum, corresponding to the minimizer of GCV function. GCV is used for an application in traveltime tomography, where the objective is to obtain the 2-D velocity distribution from the measured values of the traveltimes between sources and receivers. We present results with synthetic data, using a geological model that simulates different features, like a fault and a reservoir. The results using GCV are very good, including those contaminated with noise, and also using different regularization orders, attesting the feasibility of this technique.

  13. Mediation analysis when a continuous mediator is measured with error and the outcome follows a generalized linear model.

    PubMed

    Valeri, Linda; Lin, Xihong; VanderWeele, Tyler J

    2014-12-10

    Mediation analysis is a popular approach to examine the extent to which the effect of an exposure on an outcome is through an intermediate variable (mediator) and the extent to which the effect is direct. When the mediator is mis-measured, the validity of mediation analysis can be severely undermined. In this paper, we first study the bias of classical, non-differential measurement error on a continuous mediator in the estimation of direct and indirect causal effects in generalized linear models when the outcome is either continuous or discrete and exposure-mediator interaction may be present. Our theoretical results as well as a numerical study demonstrate that in the presence of non-linearities, the bias of naive estimators for direct and indirect effects that ignore measurement error can take unintuitive directions. We then develop methods to correct for measurement error. Three correction approaches using method of moments, regression calibration, and SIMEX are compared. We apply the proposed method to the Massachusetts General Hospital lung cancer study to evaluate the effect of genetic variants mediated through smoking on lung cancer risk.

  14. Instability and change detection in exponential families and generalized linear models, with a study of Atlantic tropical storms

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Chatterjee, S.

    2014-11-01

    Exponential family statistical distributions, including the well-known normal, binomial, Poisson, and exponential distributions, are overwhelmingly used in data analysis. In the presence of covariates, an exponential family distributional assumption for the response random variables results in a generalized linear model. However, it is rarely ensured that the parameters of the assumed distributions are stable through the entire duration of the data collection process. A failure of stability leads to nonsmoothness and nonlinearity in the physical processes that result in the data. In this paper, we propose testing for stability of parameters of exponential family distributions and generalized linear models. A rejection of the hypothesis of stable parameters leads to change detection. We derive the related likelihood ratio test statistic. We compare the performance of this test statistic to the popular normal distributional assumption dependent cumulative sum (Gaussian CUSUM) statistic in change detection problems. We study Atlantic tropical storms using the techniques developed here, so to understand whether the nature of these tropical storms has remained stable over the last few decades.

  15. General expressions for R1ρ relaxation for N-site chemical exchange and the special case of linear chains

    NASA Astrophysics Data System (ADS)

    Koss, Hans; Rance, Mark; Palmer, Arthur G.

    2017-01-01

    Exploration of dynamic processes in proteins and nucleic acids by spin-locking NMR experiments has been facilitated by the development of theoretical expressions for the R1ρ relaxation rate constant covering a variety of kinetic situations. Herein, we present a generalized approximation to the chemical exchange, Rex, component of R1ρ for arbitrary kinetic schemes, assuming the presence of a dominant major site population, derived from the negative reciprocal trace of the inverse Bloch-McConnell evolution matrix. This approximation is equivalent to first-order truncation of the characteristic polynomial derived from the Bloch-McConnell evolution matrix. For three- and four-site chemical exchange, the first-order approximations are sufficient to distinguish different kinetic schemes. We also introduce an approach to calculate R1ρ for linear N-site schemes, using the matrix determinant lemma to reduce the corresponding 3N × 3N Bloch-McConnell evolution matrix to a 3 × 3 matrix. The first- and second order-expansions of the determinant of this 3 × 3 matrix are closely related to previously derived equations for two-site exchange. The second-order approximations for linear N-site schemes can be used to obtain more accurate approximations for non-linear N-site schemes, such as triangular three-site or star four-site topologies. The expressions presented herein provide powerful means for the estimation of Rex contributions for both low (CEST-limit) and high (R1ρ-limit) radiofrequency field strengths, provided that the population of one state is dominant. The general nature of the new expressions allows for consideration of complex kinetic situations in the analysis of NMR spin relaxation data.

  16. Increasing opportunistic oral cancer screening examinations: findings from focus groups with general dentists in Puerto Rico.

    PubMed

    Psoter, Walter J; Morse, Douglas E; Sánchez-Ayendez, Melba; Vega, Carmen M Vélez; Aguilar, Maria L; Buxó-Martinez, Carmen J; Psoter, Jodi A; Kerr, Alexander R; Lane, Christina M; Scaringi, Vincent J; Elias, Augusto

    2015-06-01

    This study aims to identify educational and training modalities that dentists in Puerto Rico (PR) believe will increase the quality and quantity of opportunistic oral cancer screening examinations (OCS) in dental offices on the island. The study was conducted in three phases: a systematic search of relevant literature, an expert review and consensus panel, and focus groups (FG) involving PR general dentists. To increase OCS by dentists in PR, the FG participants proposed a small group, hands-on OCS training, an integrated oral cancer course, and readily available videos, photographs, and computer simulations to further demonstrate OCS performance and facilitate differential diagnosis. OCS training requirements for licensure and re-licensure, improving OCS dentist-patient communication skills, and establishment of an oral lesion referral center were also viewed favorably. In conclusion, general dentists in our FGs believed the quality and quantity of OCS in Puerto Rico can be increased through the application of specific continuing education and training modalities.

  17. Identifying competencies required for medication prescribing for general practice residents: a nominal group technique study

    PubMed Central

    2014-01-01

    Background Teaching of medication prescribing is a specific challenge in general practice curriculum. The aim of this study was to identify and rank the competencies required for prescribing medication for general practice residents in France. Methods Qualitative consensus study using the nominal group technique. We invited different stakeholders of the general practice curriculum and medication use in primary care to a series of meetings. The nominal group technique allowed for the quick development of a list of consensual and ranked answers to the following question: “At the end of their general practice curriculum, in terms of medication prescribing, what should residents be able to do?”. Results Four meetings were held that involved a total of 31 participants, enabling the creation of a final list of 29 ranked items, grouped in 4 domains. The four domains identified were ‘pharmacology’, ‘regulatory standards’, ‘therapeutics’, and ‘communication (both with patients and healthcare professionals)’. Overall, the five items the most highly valued across the four meetings were: ‘write a legible and understandable prescription’, ‘identify specific populations’, ‘prescribe the doses and durations following the indication’, ‘explain a lack of medication prescription to the patient’, ‘decline inappropriate medication request’. The ‘communication skills’ domain was the domain with the highest number of items (10 items), and with the most highly-valued items. Conclusion The study results suggest a need for developing general practice residents’ communication skills regarding medication prescribing. PMID:25084813

  18. Renormalization group equations and matching in a general quantum field theory with kinetic mixing

    NASA Astrophysics Data System (ADS)

    Fonseca, Renato M.; Malinský, Michal; Staub, Florian

    2013-11-01

    We work out a set of simple rules for adopting the two-loop renormalization group equations of a generic gauge field theory given in the seminal works of Machacek and Vaughn to the most general case with an arbitrary number of Abelian gauge factors and comment on the extra subtleties possibly encountered upon matching a set of effective gauge theories in such a framework.

  19. Generalization of Weber's adiabatic bond charge model to amorphous group IV semiconductors

    NASA Astrophysics Data System (ADS)

    Winer, K.; Wooten, F.

    1984-11-01

    The generalization of Weber's adiabatic bond charge model to amorphous group IV semiconductors is described. Methods of relaxing the coordinates to their equilibrium configuration and of calculating the dynamical matrix for the phonon spectra are given. Particular emphasis is given to the optimization of the Coulomb subroutines required in this model. Estimates of computation time are included for the calculation of equilibrium configuration on a Cray computer.

  20. Focus group evaluation of teachers' views on a new general education program in Hong Kong.

    PubMed

    Shek, Daniel T L; Yu, Lu; Chi, Xinli

    2017-02-01

    Using teachers' focus group interviews (n=40), this study examined the impact of the General University Requirements (GUR) implemented at The Hong Kong Polytechnic University (PolyU). Results showed that teachers were generally satisfied with the GUR subjects and its implementation in its second year. Teachers regarded the design of GUR subjects was good and the students generally welcomed the subjects. Interactive teaching and learning methods adopted in GUR subjects such as fieldwork, hands-on projects, and team debates were highly appreciated by the respondents. Teachers also reflected that the GUR had promoted the intrapersonal and interpersonal development of the students. However, several challenges were also reported by teachers, including the difficulty level of Freshman Seminar subjects and lack of interaction in some GUR subjects, which suggested directions for further improvements.

  1. Psychometric Properties of the Generalized Anxiety Disorder Questionnaire for DSM-IV Among Four Racial Groups

    PubMed Central

    Robinson, Christina M.; Klenck, Suzanne C.; Norton, Peter J.

    2010-01-01

    The Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV) is a self-report diagnostic measure of generalized anxiety disorder. Previous studies have established the psychometric properties of the GAD-Q-IV revealing excellent diagnostic specificity and sensitivity as well as good test-retest reliability and convergent and discriminant validity (Newman et al., 2002). Recent analyses with other measures of anxiety symptoms have revealed differences across racial or national groups. Given that the GAD-Q-IV was tested primarily on Caucasian (78%) participants, the purpose of this study was to demonstrate the psychometric properties of the GAD-Q-IV across four racial groups: African American, Caucasian, Hispanic/Latino, and Asian. A student sample of 585 undergraduate psychology students completed the GAD-Q-IV as well as other measures of anxiety symptoms. A clinical replication sample was obtained from 188 clinical participants who completed the GAD-Q-IV as part of a larger psychotherapy study. Results indicated excellent and very similar factor structures in the student sample, and similar psychometric properties across both samples across the racial groups. Implications for the use of the GAD-Q-IV across racial groups are discussed. PMID:20830629

  2. Using a generalized linear mixed model approach to explore the role of age, motor proficiency, and cognitive styles in children's reach estimation accuracy.

    PubMed

    Caçola, Priscila M; Pant, Mohan D

    2014-10-01

    The purpose was to use a multi-level statistical technique to analyze how children's age, motor proficiency, and cognitive styles interact to affect accuracy on reach estimation tasks via Motor Imagery and Visual Imagery. Results from the Generalized Linear Mixed Model analysis (GLMM) indicated that only the 7-year-old age group had significant random intercepts for both tasks. Motor proficiency predicted accuracy in reach tasks, and cognitive styles (object scale) predicted accuracy in the motor imagery task. GLMM analysis is suitable to explore age and other parameters of development. In this case, it allowed an assessment of motor proficiency interacting with age to shape how children represent, plan, and act on the environment.

  3. Cadmium-hazard mapping using a general linear regression model (Irr-Cad) for rapid risk assessment.

    PubMed

    Simmons, Robert W; Noble, Andrew D; Pongsakul, P; Sukreeyapongse, O; Chinabut, N

    2009-02-01

    Research undertaken over the last 40 years has identified the irrefutable relationship between the long-term consumption of cadmium (Cd)-contaminated rice and human Cd disease. In order to protect public health and livelihood security, the ability to accurately and rapidly determine spatial Cd contamination is of high priority. During 2001-2004, a General Linear Regression Model Irr-Cad was developed to predict the spatial distribution of soil Cd in a Cd/Zn co-contaminated cascading irrigated rice-based system in Mae Sot District, Tak Province, Thailand (Longitude E 98 degrees 59'-E 98 degrees 63' and Latitude N 16 degrees 67'-16 degrees 66'). The results indicate that Irr-Cad accounted for 98% of the variance in mean Field Order total soil Cd. Preliminary validation indicated that Irr-Cad 'predicted' mean Field Order total soil Cd, was significantly (p < 0.001) correlated (R (2) = 0.92) with 'observed' mean Field Order total soil Cd values. Field Order is determined by a given field's proximity to primary outlets from in-field irrigation channels and subsequent inter-field irrigation flows. This in turn determines Field Order in Irrigation Sequence (Field Order(IS)). Mean Field Order total soil Cd represents the mean total soil Cd (aqua regia-digested) for a given Field Order(IS). In 2004-2005, Irr-Cad was utilized to evaluate the spatial distribution of total soil Cd in a 'high-risk' area of Mae Sot District. Secondary validation on six randomly selected field groups verified that Irr-Cad predicted mean Field Order total soil Cd and was significantly (p < 0.001) correlated with the observed mean Field Order total soil Cd with R (2) values ranging from 0.89 to 0.97. The practical applicability of Irr-Cad is in its minimal input requirements, namely the classification of fields in terms of Field Order(IS), strategic sampling of all primary fields and laboratory based determination of total soil Cd (T-Cd(P)) and the use of a weighed coefficient for Cd (Coeff

  4. A generalized electrostatic micro-mirror (GEM) model for a two-axis convex piecewise linear shaped MEMS mirror

    NASA Astrophysics Data System (ADS)

    Edwards, C. L.; Edwards, M. L.

    2009-05-01

    MEMS micro-mirror technology offers the opportunity to replace larger optical actuators with smaller, faster ones for lidar, network switching, and other beam steering applications. Recent developments in modeling and simulation of MEMS two-axis (tip-tilt) mirrors have resulted in closed-form solutions that are expressed in terms of physical, electrical and environmental parameters related to the MEMS device. The closed-form analytical expressions enable dynamic time-domain simulations without excessive computational overhead and are referred to as the Micro-mirror Pointing Model (MPM). Additionally, these first-principle models have been experimentally validated with in-situ static, dynamic, and stochastic measurements illustrating their reliability. These models have assumed that the mirror has a rectangular shape. Because the corners can limit the dynamic operation of a rectangular mirror, it is desirable to shape the mirror, e.g., mitering the corners. Presented in this paper is the formulation of a generalized electrostatic micromirror (GEM) model with an arbitrary convex piecewise linear shape that is readily implemented in MATLAB and SIMULINK for steady-state and dynamic simulations. Additionally, such a model permits an arbitrary shaped mirror to be approximated as a series of linearly tapered segments. Previously, "effective area" arguments were used to model a non-rectangular shaped mirror with an equivalent rectangular one. The GEM model shows the limitations of this approach and provides a pre-fabrication tool for designing mirror shapes.

  5. Variable selection in Bayesian generalized linear-mixed models: an illustration using candidate gene case-control association studies.

    PubMed

    Tsai, Miao-Yu

    2015-03-01

    The problem of variable selection in the generalized linear-mixed models (GLMMs) is pervasive in statistical practice. For the purpose of variable selection, many methodologies for determining the best subset of explanatory variables currently exist according to the model complexity and differences between applications. In this paper, we develop a "higher posterior probability model with bootstrap" (HPMB) approach to select explanatory variables without fitting all possible GLMMs involving a small or moderate number of explanatory variables. Furthermore, to save computational load, we propose an efficient approximation approach with Laplace's method and Taylor's expansion to approximate intractable integrals in GLMMs. Simulation studies and an application of HapMap data provide evidence that this selection approach is computationally feasible and reliable for exploring true candidate genes and gene-gene associations, after adjusting for complex structures among clusters.

  6. SAS macro programs for geographically weighted generalized linear modeling with spatial point data: applications to health research.

    PubMed

    Chen, Vivian Yi-Ju; Yang, Tse-Chuan

    2012-08-01

    An increasing interest in exploring spatial non-stationarity has generated several specialized analytic software programs; however, few of these programs can be integrated natively into a well-developed statistical environment such as SAS. We not only developed a set of SAS macro programs to fill this gap, but also expanded the geographically weighted generalized linear modeling (GWGLM) by integrating the strengths of SAS into the GWGLM framework. Three features distinguish our work. First, the macro programs of this study provide more kernel weighting functions than the existing programs. Second, with our codes the users are able to better specify the bandwidth selection process compared to the capabilities of existing programs. Third, the development of the macro programs is fully embedded in the SAS environment, providing great potential for future exploration of complicated spatially varying coefficient models in other disciplines. We provided three empirical examples to illustrate the use of the SAS macro programs and demonstrated the advantages explained above.

  7. Correlated-imaging-based chosen plaintext attack on general cryptosystems composed of linear canonical transforms and phase encodings

    NASA Astrophysics Data System (ADS)

    Wu, Jingjing; Liu, Wei; Liu, Zhengjun; Liu, Shutian

    2015-03-01

    We introduce a chosen-plaintext attack scheme on general optical cryptosystems that use linear canonical transform and phase encoding based on correlated imaging. The plaintexts are chosen as Gaussian random real number matrixes, and the corresponding ciphertexts are regarded as prior knowledge of the proposed attack method. To establish the reconstruct of the secret plaintext, correlated imaging is employed using the known resources. Differing from the reported attack methods, there is no need to decipher the distribution of the decryption key. The original secret image can be directly recovered by the attack in the absence of decryption key. In addition, the improved cryptosystems combined with pixel scrambling operations are also vulnerable to the proposed attack method. Necessary mathematical derivations and numerical simulations are carried out to demonstrate the validity of the proposed attack scheme.

  8. Metrics of separation performance in chromatography: Part 3: General separation performance of linear solvent strength gradient liquid chromatography.

    PubMed

    Blumberg, Leonid M; Desmet, Gert

    2015-09-25

    The separation performance metrics defined in Part 1 of this series are applied to the evaluation of general separation performance of linear solvent strength (LSS) gradient LC. Among the evaluated metrics was the peak capacity of an arbitrary segment of a chromatogram. Also evaluated were the peak width, the separability of two solutes, the utilization of separability, and the speed of analysis-all at an arbitrary point of a chromatogram. The means are provided to express all these metrics as functions of an arbitrary time during LC analysis, as functions of an arbitrary outlet solvent strength changing during the analysis, as functions of parameters of the solutes eluting during the analysis, and as functions of several other factors. The separation performance of gradient LC is compared with the separation performance of temperature-programmed GC evaluated in Part 2.

  9. Trajectories of Change in University Students' General Views of Group Work Following One Single Group Assignment: Significance of Instructional Context and Multidimensional Aspects of Experience

    ERIC Educational Resources Information Center

    Wosnitza, Marold; Volet, Simone

    2014-01-01

    This paper examines how distinct trajectories of change in students' general views of group work over the duration of one single group assignment could be explained by multidimensional aspects of their experience and the overall instructional context. Science (336) and Education (377) students involved in a semester-long group assignment…

  10. PyR@TE. Renormalization group equations for general gauge theories

    NASA Astrophysics Data System (ADS)

    Lyonnet, F.; Schienbein, I.; Staub, F.; Wingerter, A.

    2014-03-01

    Although the two-loop renormalization group equations for a general gauge field theory have been known for quite some time, deriving them for specific models has often been difficult in practice. This is mainly due to the fact that, albeit straightforward, the involved calculations are quite long, tedious and prone to error. The present work is an attempt to facilitate the practical use of the renormalization group equations in model building. To that end, we have developed two completely independent sets of programs written in Python and Mathematica, respectively. The Mathematica scripts will be part of an upcoming release of SARAH 4. The present article describes the collection of Python routines that we dubbed PyR@TE which is an acronym for “Python Renormalization group equations At Two-loop for Everyone”. In PyR@TE, once the user specifies the gauge group and the particle content of the model, the routines automatically generate the full two-loop renormalization group equations for all (dimensionless and dimensionful) parameters. The results can optionally be exported to LaTeX and Mathematica, or stored in a Python data structure for further processing by other programs. For ease of use, we have implemented an interactive mode for PyR@TE in form of an IPython Notebook. As a first application, we have generated with PyR@TE the renormalization group equations for several non-supersymmetric extensions of the Standard Model and found some discrepancies with the existing literature. Catalogue identifier: AERV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERV_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 924959 No. of bytes in distributed program, including test data, etc.: 495197 Distribution format: tar.gz Programming language: Python. Computer

  11. Analytic Coarse-Mesh Finite-Difference Method Generalized for Heterogeneous Multidimensional Two-Group Diffusion Calculations

    SciTech Connect

    Garcia-Herranz, Nuria; Cabellos, Oscar; Aragones, Jose M.; Ahnert, Carol

    2003-05-15

    In order to take into account in a more effective and accurate way the intranodal heterogeneities in coarse-mesh finite-difference (CMFD) methods, a new equivalent parameter generation methodology has been developed and tested. This methodology accounts for the dependence of the nodal homogeneized two-group cross sections and nodal coupling factors, with interface flux discontinuity (IFD) factors that account for heterogeneities on the flux-spectrum and burnup intranodal distributions as well as on neighbor effects.The methodology has been implemented in an analytic CMFD method, rigorously obtained for homogeneous nodes with transverse leakage and generalized now for heterogeneous nodes by including IFD heterogeneity factors. When intranodal mesh node heterogeneity vanishes, the heterogeneous solution tends to the analytic homogeneous nodal solution. On the other hand, when intranodal heterogeneity increases, a high accuracy is maintained since the linear and nonlinear feedbacks on equivalent parameters have been shown to be as a very effective way of accounting for heterogeneity effects in two-group multidimensional coarse-mesh diffusion calculations.

  12. [Non linear principal component analysis and clues for a differential approach of five groups experiencing social precariousness].

    PubMed

    Meyer, C

    2008-01-01

    We wished to develop an original way of taking care of people experiencing great social precariousness. Our purpose was to develop communication and relational skills, to stimulate expression of emotions and feelings, to bring out personal resources, to increase well-being, motivation and self-esteem, and thus favour rehabilitation. Our sample is composed of long-term unemployed people, of people benefiting from measures of integration into the working process, of people living in community homes, of drug addicts, and of drug-addicted female prisoners. Our research is based on an integrated quantitative and qualitative methodology, with rating scales for the artistic production and observational frames for items of verbal and non-verbal behaviour completing the psychometric questionnaires. It is an action research; we use art therapy, which is a common practice in the health sector, especially with subjects having problems expressing there feelings through words. We have carried out a non linear principal component analysis (PRINCALS) on the data of the projective test (Rotter), as well as a between groups comparison of the responses to the questionnaire on life satisfaction (FLZ), with the help of the Mann-Whitney test. It is from these comparisons that we are able to draw out a few clues for differential treating strategies, depending on the inclusion into the five sub-groups that we have followed.

  13. Acceptance criteria for flattening filter-free photon beam from standard medical electron linear accelerator: AERB task group recommendations

    PubMed Central

    Sahani, G.; Sharma, S. D.; Sharma, P. K. Dash; Deshpande, D. D.; Negi, P. S.; Sathianarayanan, V. K.; Rath, G. K.

    2014-01-01

    Medical electron linear accelerators with the capability of generating unflat photon (flattening filter-free, FFF) beams are also available commercially for clinical applications in radiotherapy. However, the beam characteristics evaluation criteria and parameters are not yet available for such photon beams. Atomic Energy Regulatory Board (AERB) of India constituted a Task Group comprising experts from regulatory agency, advisory body/research and technical institutions, and clinical radiotherapy centers in the country to evolve and recommend the acceptance criteria for the flattening filter-free (FFF) photon beams. The Task Group thoroughly reviewed the literature and inputs of the manufactures/suppliers of the FFF linac and recommended a set of dosimetry parameters for evaluating the characteristics of the unflat photon beam. The recommendations included the evaluation of quality index, degree of unflatness, difference in percentage surface dose between flat and unflat photon beams, percentage depth dose at 10 cm depth, off-axis-ratios and radiation beam penumbra. The recommended parameters were evaluated for FFF photon beams generated by three different models of the linac, and it was observed that recommended evaluation methods are simple and easy to be implemented with the existing dosimetry and quality assurance infrastructure of the linac facilities of the radiotherapy departments. Recommendations were also made for periodic quality control check of the unflat photon beams and constancy evaluation in the beam characteristics. PMID:25525307

  14. General intellectual impairment in chronic right hemisphere damaged patients with anosognosia: a group study.

    PubMed

    Mattioli, F; Gialanella, B; Stampatori, C; Scarpazza, C

    2012-01-01

    The study evaluates the possible relations between cognitive impairment, persisting anosognosia for hemiplegia and peripersonal neglect. Thirty eight chronic right hemisphere stroke patients were divided in three age- and education-matched groups: A (n = 13) patients with left hemiparesis, peripersonal neglect, and anosognosia for hemiplegia; B (n = 12) patients with left hemiparesis and peripersonal neglect, and C (n = 13) patients with left hemiparesis only. We used MMSE and WAIS Verbal IQ and verbal subtests to assess cognitive impairment in patients, in order to avoid a bias due to visuospatial deficit, which is common in patients with neglect. VIQ, Information, Digit Span and Vocabulary WAIS subtests as well as MMSE were found to be significantly lower in group A versus group B. No difference was found in any test between groups B and C, indicating a general worse cognition in patients compared to those without anosognosia for hemiplegia. Patients with anosognosia for hemiplegia also showed larger brain lesions and, more frequently, frontal, parietal, temporal and basal ganglia involvement, particularly if they had low verbal IQ, indicating a relationship between cognitive impairment, persisting anosognosia for hemiplegia and large right hemisphere lesions.

  15. A Focus Group on Dental Pain Complaints with General Medical Practitioners: Developing a Treatment Algorithm.

    PubMed

    Carter, Ava Elizabeth; Carter, Geoff; Abbey, Robyn

    2016-01-01

    Objective. The differential diagnosis of pain in the mouth can be challenging for general medical practitioners (GMPs) as many different dental problems can present with similar signs and symptoms. This study aimed to create a treatment algorithm for GMPs to effectively and appropriately refer the patients and prescribe antibiotics. Design. The study design is comprised of qualitative focus group discussions. Setting and Subjects. Groups of GMPs within the Gold Coast and Brisbane urban and city regions. Outcome Measures. Content thematically analysed and treatment algorithm developed. Results. There were 5 focus groups with 8-9 participants per group. Addressing whether antibiotics should be given to patients with dental pain was considered very important to GMPs to prevent overtreatment and creating antibiotic resistance. Many practitioners were unsure of what the different forms of dental pains represent. 90% of the practitioners involved agreed that the treatment algorithm was useful to daily practice. Conclusion. Common dental complaints and infections are seldom surgical emergencies but can result in prolonged appointments for those GMPs who do not regularly deal with these issues. The treatment algorithm for referral processes and prescriptions was deemed easily downloadable and simple to interpret and detailed but succinct enough for clinical use by GMPs.

  16. A Focus Group on Dental Pain Complaints with General Medical Practitioners: Developing a Treatment Algorithm

    PubMed Central

    Carter, Geoff; Abbey, Robyn

    2016-01-01

    Objective. The differential diagnosis of pain in the mouth can be challenging for general medical practitioners (GMPs) as many different dental problems can present with similar signs and symptoms. This study aimed to create a treatment algorithm for GMPs to effectively and appropriately refer the patients and prescribe antibiotics. Design. The study design is comprised of qualitative focus group discussions. Setting and Subjects. Groups of GMPs within the Gold Coast and Brisbane urban and city regions. Outcome Measures. Content thematically analysed and treatment algorithm developed. Results. There were 5 focus groups with 8-9 participants per group. Addressing whether antibiotics should be given to patients with dental pain was considered very important to GMPs to prevent overtreatment and creating antibiotic resistance. Many practitioners were unsure of what the different forms of dental pains represent. 90% of the practitioners involved agreed that the treatment algorithm was useful to daily practice. Conclusion. Common dental complaints and infections are seldom surgical emergencies but can result in prolonged appointments for those GMPs who do not regularly deal with these issues. The treatment algorithm for referral processes and prescriptions was deemed easily downloadable and simple to interpret and detailed but succinct enough for clinical use by GMPs. PMID:27462469

  17. Accounting for uncertainty in confounder and effect modifier selection when estimating average causal effects in generalized linear models.

    PubMed

    Wang, Chi; Dominici, Francesca; Parmigiani, Giovanni; Zigler, Corwin Matthew

    2015-09-01

    Confounder selection and adjustment are essential elements of assessing the causal effect of an exposure or treatment in observational studies. Building upon work by Wang et al. (2012, Biometrics 68, 661-671) and Lefebvre et al. (2014, Statistics in Medicine 33, 2797-2813), we propose and evaluate a Bayesian method to estimate average causal effects in studies with a large number of potential confounders, relatively few observations, likely interactions between confounders and the exposure of interest, and uncertainty on which confounders and interaction terms should be included. Our method is applicable across all exposures and outcomes that can be handled through generalized linear models. In this general setting, estimation of the average causal effect is different from estimation of the exposure coefficient in the outcome model due to noncollapsibility. We implement a Bayesian bootstrap procedure to integrate over the distribution of potential confounders and to estimate the causal effect. Our method permits estimation of both the overall population causal effect and effects in specified subpopulations, providing clear characterization of heterogeneous exposure effects that may vary considerably across different covariate profiles. Simulation studies demonstrate that the proposed method performs well in small sample size situations with 100-150 observations and 50 covariates. The method is applied to data on 15,060 US Medicare beneficiaries diagnosed with a malignant brain tumor between 2000 and 2009 to evaluate whether surgery reduces hospital readmissions within 30 days of diagnosis.

  18. Effect of Smoothing in Generalized Linear Mixed Models on the Estimation of Covariance Parameters for Longitudinal Data.

    PubMed

    Mullah, Muhammad Abu Shadeque; Benedetti, Andrea

    2016-11-01

    Besides being mainly used for analyzing clustered or longitudinal data, generalized linear mixed models can also be used for smoothing via restricting changes in the fit at the knots in regression splines. The resulting models are usually called semiparametric mixed models (SPMMs). We investigate the effect of smoothing using SPMMs on the correlation and variance parameter estimates for serially correlated longitudinal normal, Poisson and binary data. Through simulations, we compare the performance of SPMMs to other simpler methods for estimating the nonlinear association such as fractional polynomials, and using a parametric nonlinear function. Simulation results suggest that, in general, the SPMMs recover the true curves very well and yield reasonable estimates of the correlation and variance parameters. However, for binary outcomes, SPMMs produce biased estimates of the variance parameters for high serially correlated data. We apply these methods to a dataset investigating the association between CD4 cell count and time since seroconversion for HIV infected men enrolled in the Multicenter AIDS Cohort Study.

  19. The statistical performance of an MCF-7 cell culture assay evaluated using generalized linear mixed models and a score test.

    PubMed

    Rey deCastro, B; Neuberg, Donna

    2007-05-30

    Biological assays often utilize experimental designs where observations are replicated at multiple levels, and where each level represents a separate component of the assay's overall variance. Statistical analysis of such data usually ignores these design effects, whereas more sophisticated methods would improve the statistical power of assays. This report evaluates the statistical performance of an in vitro MCF-7 cell proliferation assay (E-SCREEN) by identifying the optimal generalized linear mixed model (GLMM) that accurately represents the assay's experimental design and variance components. Our statistical assessment found that 17beta-oestradiol cell culture assay data were best modelled with a GLMM configured with a reciprocal link function, a gamma error distribution, and three sources of design variation: plate-to-plate; well-to-well, and the interaction between plate-to-plate variation and dose. The gamma-distributed random error of the assay was estimated to have a coefficient of variation (COV) = 3.2 per cent, and a variance component score test described by X. Lin found that each of the three variance components were statistically significant. The optimal GLMM also confirmed the estrogenicity of five weakly oestrogenic polychlorinated biphenyls (PCBs 17, 49, 66, 74, and 128). Based on information criteria, the optimal gamma GLMM consistently out-performed equivalent naive normal and log-normal linear models, both with and without random effects terms. Because the gamma GLMM was by far the best model on conceptual and empirical grounds, and requires only trivially more effort to use, we encourage its use and suggest that naive models be avoided when possible.

  20. The Weyl group and asymptotics: All supergravity billiards have a closed form general integral

    NASA Astrophysics Data System (ADS)

    Fré, Pietro; Sorin, Alexander S.

    2009-07-01

    In this paper we show that all supergravity billiards corresponding to σ-models on any U/H non-compact-symmetric space and obtained by compactifying supergravity to D=3 admit a closed form general integral depending analytically on a complete set of integration constants. The key point in establishing the integration algorithm is provided by an upper triangular embedding of the solvable Lie algebra associated with U/H into sl(N,R) which is guaranteed to exist for all non-compact symmetric spaces and also for homogeneous special geometries non-corresponding to symmetric spaces. In this context we establish a remarkable relation between the end-points of the time-flow and the properties of the Weyl group. The asymptotic states of the developing Universe are in one-to-one correspondence with the elements of the Weyl group which is a property of the Tits-Satake universality classes and not of their single representatives. Furthermore the Weyl group admits a natural ordering in terms of ℓ, the number of reflections with respect to the simple roots. The direction of time flows is always from the minimal accessible value of ℓ to the maximum one or vice versa.

  1. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  2. Use of reflectance spectrophotometry and colorimetry in a general linear model for the determination of the age of bruises.

    PubMed

    Hughes, Vanessa K; Langlois, Neil E I

    2010-12-01

    Bruises can have medicolegal significance such that the age of a bruise may be an important issue. This study sought to determine if colorimetry or reflectance spectrophotometry could be employed to objectively estimate the age of bruises. Based on a previously described method, reflectance spectrophotometric scans were obtained from bruises using a Cary 100 Bio spectrophotometer fitted with a fibre-optic reflectance probe. Measurements were taken from the bruise and a control area. Software was used to calculate the first derivative at 490 and 480 nm; the proportion of oxygenated hemoglobin was calculated using an isobestic point method and a software application converted the scan data into colorimetry data. In addition, data on factors that might be associated with the determination of the age of a bruise: subject age, subject sex, degree of trauma, bruise size, skin color, body build, and depth of bruise were recorded. From 147 subjects, 233 reflectance spectrophotometry scans were obtained for analysis. The age of the bruises ranged from 0.5 to 231.5 h. A General Linear Model analysis method was used. This revealed that colorimetric measurement of the yellowness of a bruise accounted for 13% of the bruise age. By incorporation of the other recorded data (as above), yellowness could predict up to 32% of the age of a bruise-implying that 68% of the variation was dependent on other factors. However, critical appraisal of the model revealed that the colorimetry method of determining the age of a bruise was affected by skin tone and required a measure of the proportion of oxygenated hemoglobin, which is obtained by spectrophotometric methods. Using spectrophotometry, the first derivative at 490 nm alone accounted for 18% of the bruise age estimate. When additional factors (subject sex, bruise depth and oxygenation of hemoglobin) were included in the General Linear Model this increased to 31%-implying that 69% of the variation was dependent on other factors. This

  3. Multisite multivariate modeling of daily precipitation and temperature in the Canadian Prairie Provinces using generalized linear models

    NASA Astrophysics Data System (ADS)

    Asong, Zilefac E.; Khaliq, M. N.; Wheater, H. S.

    2016-11-01

    Based on the Generalized Linear Model (GLM) framework, a multisite stochastic modelling approach is developed using daily observations of precipitation and minimum and maximum temperatures from 120 sites located across the Canadian Prairie Provinces: Alberta, Saskatchewan and Manitoba. Temperature is modeled using a two-stage normal-heteroscedastic model by fitting mean and variance components separately. Likewise, precipitation occurrence and conditional precipitation intensity processes are modeled separately. The relationship between precipitation and temperature is accounted for by using transformations of precipitation as covariates to predict temperature fields. Large scale atmospheric covariates from the National Center for Environmental Prediction Reanalysis-I, teleconnection indices, geographical site attributes, and observed precipitation and temperature records are used to calibrate these models for the 1971-2000 period. Validation of the developed models is performed on both pre- and post-calibration period data. Results of the study indicate that the developed models are able to capture spatiotemporal characteristics of observed precipitation and temperature fields, such as inter-site and inter-variable correlation structure, and systematic regional variations present in observed sequences. A number of simulated weather statistics ranging from seasonal means to characteristics of temperature and precipitation extremes and some of the commonly used climate indices are also found to be in close agreement with those derived from observed data. This GLM-based modelling approach will be developed further for multisite statistical downscaling of Global Climate Model outputs to explore climate variability and change in this region of Canada.

  4. Automatic optimal filament segmentation with sub-pixel accuracy using generalized linear models and B-spline level-sets

    PubMed Central

    Xiao, Xun; Geyer, Veikko F.; Bowne-Anderson, Hugo; Howard, Jonathon; Sbalzarini, Ivo F.

    2016-01-01

    Biological filaments, such as actin filaments, microtubules, and cilia, are often imaged using different light-microscopy techniques. Reconstructing the filament curve from the acquired images constitutes the filament segmentation problem. Since filaments have lower dimensionality than the image itself, there is an inherent trade-off between tracing the filament with sub-pixel accuracy and avoiding noise artifacts. Here, we present a globally optimal filament segmentation method based on B-spline vector level-sets and a generalized linear model for the pixel intensity statistics. We show that the resulting optimization problem is convex and can hence be solved with global optimality. We introduce a simple and efficient algorithm to compute such optimal filament segmentations, and provide an open-source implementation as an ImageJ/Fiji plugin. We further derive an information-theoretic lower bound on the filament segmentation error, quantifying how well an algorithm could possibly do given the information in the image. We show that our algorithm asymptotically reaches this bound in the spline coefficients. We validate our method in comprehensive benchmarks, compare with other methods, and show applications from fluorescence, phase-contrast, and dark-field microscopy. PMID:27104582

  5. Optimizing the general linear model for functional near-infrared spectroscopy: an adaptive hemodynamic response function approach

    PubMed Central

    Uga, Minako; Dan, Ippeita; Sano, Toshifumi; Dan, Haruka; Watanabe, Eiju

    2014-01-01

    Abstract. An increasing number of functional near-infrared spectroscopy (fNIRS) studies utilize a general linear model (GLM) approach, which serves as a standard statistical method for functional magnetic resonance imaging (fMRI) data analysis. While fMRI solely measures the blood oxygen level dependent (BOLD) signal, fNIRS measures the changes of oxy-hemoglobin (oxy-Hb) and deoxy-hemoglobin (deoxy-Hb) signals at a temporal resolution severalfold higher. This suggests the necessity of adjusting the temporal parameters of a GLM for fNIRS signals. Thus, we devised a GLM-based method utilizing an adaptive hemodynamic response function (HRF). We sought the optimum temporal parameters to best explain the observed time series data during verbal fluency and naming tasks. The peak delay of the HRF was systematically changed to achieve the best-fit model for the observed oxy- and deoxy-Hb time series data. The optimized peak delay showed different values for each Hb signal and task. When the optimized peak delays were adopted, the deoxy-Hb data yielded comparable activations with similar statistical power and spatial patterns to oxy-Hb data. The adaptive HRF method could suitably explain the behaviors of both Hb parameters during tasks with the different cognitive loads during a time course, and thus would serve as an objective method to fully utilize the temporal structures of all fNIRS data. PMID:26157973

  6. Generalized linear solvation energy model applied to solute partition coefficients in ionic liquid-supercritical carbon dioxide systems.

    PubMed

    Planeta, Josef; Karásek, Pavel; Hohnová, Barbora; Sťavíková, Lenka; Roth, Michal

    2012-08-10

    Biphasic solvent systems composed of an ionic liquid (IL) and supercritical carbon dioxide (scCO(2)) have become frequented in synthesis, extractions and electrochemistry. In the design of related applications, information on interphase partitioning of the target organics is essential, and the infinite-dilution partition coefficients of the organic solutes in IL-scCO(2) systems can conveniently be obtained by supercritical fluid chromatography. The data base of experimental partition coefficients obtained previously in this laboratory has been employed to test a generalized predictive model for the solute partition coefficients. The model is an amended version of that described before by Hiraga et al. (J. Supercrit. Fluids, in press). Because of difficulty of the problem to be modeled, the model involves several different concepts - linear solvation energy relationships, density-dependent solvent power of scCO(2), regular solution theory, and the Flory-Huggins theory of athermal solutions. The model shows a moderate success in correlating the infinite-dilution solute partition coefficients (K-factors) in individual IL-scCO(2) systems at varying temperature and pressure. However, larger K-factor data sets involving multiple IL-scCO(2) systems appear to be beyond reach of the model, especially when the ILs involved pertain to different cation classes.

  7. Estimation of breeding values for mean and dispersion, their variance and correlation using double hierarchical generalized linear models.

    PubMed

    Felleki, M; Lee, D; Lee, Y; Gilmour, A R; Rönnegård, L

    2012-12-01

    The possibility of breeding for uniform individuals by selecting animals expressing a small response to environment has been studied extensively in animal breeding. Bayesian methods for fitting models with genetic components in the residual variance have been developed for this purpose, but have limitations due to the computational demands. We use the hierarchical (h)-likelihood from the theory of double hierarchical generalized linear models (DHGLM) to derive an estimation algorithm that is computationally feasible for large datasets. Random effects for both the mean and residual variance parts of the model are estimated together with their variance/covariance components. An important feature of the algorithm is that it can fit a correlation between the random effects for mean and variance. An h-likelihood estimator is implemented in the R software and an iterative reweighted least square (IRWLS) approximation of the h-likelihood is implemented using ASReml. The difference in variance component estimates between the two implementations is investigated, as well as the potential bias of the methods, using simulations. IRWLS gives the same results as h-likelihood in simple cases with no severe indication of bias. For more complex cases, only IRWLS could be used, and bias did appear. The IRWLS is applied on the pig litter size data previously analysed by Sorensen & Waagepetersen (2003) using Bayesian methodology. The estimates we obtained by using IRWLS are similar to theirs, with the estimated correlation between the random genetic effects being -0·52 for IRWLS and -0·62 in Sorensen & Waagepetersen (2003).

  8. SNP_NLMM: A SAS Macro to Implement a Flexible Random Effects Density for Generalized Linear and Nonlinear Mixed Models

    PubMed Central

    Vock, David M.; Davidian, Marie; Tsiatis, Anastasios A.

    2014-01-01

    Generalized linear and nonlinear mixed models (GMMMs and NLMMs) are commonly used to represent non-Gaussian or nonlinear longitudinal or clustered data. A common assumption is that the random effects are Gaussian. However, this assumption may be unrealistic in some applications, and misspecification of the random effects density may lead to maximum likelihood parameter estimators that are inconsistent, biased, and inefficient. Because testing if the random effects are Gaussian is difficult, previous research has recommended using a flexible random effects density. However, computational limitations have precluded widespread use of flexible random effects densities for GLMMs and NLMMs. We develop a SAS macro, SNP_NLMM, that overcomes the computational challenges to fit GLMMs and NLMMs where the random effects are assumed to follow a smooth density that can be represented by the seminonparametric formulation proposed by Gallant and Nychka (1987). The macro is flexible enough to allow for any density of the response conditional on the random effects and any nonlinear mean trajectory. We demonstrate the SNP_NLMM macro on a GLMM of the disease progression of toenail infection and on a NLMM of intravenous drug concentration over time. PMID:24688453

  9. General characterization of Tityus fasciolatus scorpion venom. Molecular identification of toxins and localization of linear B-cell epitopes.

    PubMed

    Mendes, T M; Guimarães-Okamoto, P T C; Machado-de-Avila, R A; Oliveira, D; Melo, M M; Lobato, Z I; Kalapothakis, E; Chávez-Olórtegui, C

    2015-06-01

    This communication describes the general characteristics of the venom from the Brazilian scorpion Tityus fasciolatus, which is an endemic species found in the central Brazil (States of Goiás and Minas Gerais), being responsible for sting accidents in this area. The soluble venom obtained from this scorpion is toxic to mice being the LD50 is 2.984 mg/kg (subcutaneally). SDS-PAGE of the soluble venom resulted in 10 fractions ranged in size from 6 to 10-80 kDa. Sheep were employed for anti-T. fasciolatus venom serum production. Western blotting analysis showed that most of these venom proteins are immunogenic. T. fasciolatus anti-venom revealed consistent cross-reactivity with venom antigens from Tityus serrulatus. Using known primers for T. serrulatus toxins, we have identified three toxins sequences from T. fasciolatus venom. Linear epitopes of these toxins were localized and fifty-five overlapping pentadecapeptides covering complete amino acid sequence of the three toxins were synthesized in cellulose membrane (spot-synthesis technique). The epitopes were located on the 3D structures and some important residues for structure/function were identified.

  10. Automatic optimal filament segmentation with sub-pixel accuracy using generalized linear models and B-spline level-sets.

    PubMed

    Xiao, Xun; Geyer, Veikko F; Bowne-Anderson, Hugo; Howard, Jonathon; Sbalzarini, Ivo F

    2016-08-01

    Biological filaments, such as actin filaments, microtubules, and cilia, are often imaged using different light-microscopy techniques. Reconstructing the filament curve from the acquired images constitutes the filament segmentation problem. Since filaments have lower dimensionality than the image itself, there is an inherent trade-off between tracing the filament with sub-pixel accuracy and avoiding noise artifacts. Here, we present a globally optimal filament segmentation method based on B-spline vector level-sets and a generalized linear model for the pixel intensity statistics. We show that the resulting optimization problem is convex and can hence be solved with global optimality. We introduce a simple and efficient algorithm to compute such optimal filament segmentations, and provide an open-source implementation as an ImageJ/Fiji plugin. We further derive an information-theoretic lower bound on the filament segmentation error, quantifying how well an algorithm could possibly do given the information in the image. We show that our algorithm asymptotically reaches this bound in the spline coefficients. We validate our method in comprehensive benchmarks, compare with other methods, and show applications from fluorescence, phase-contrast, and dark-field microscopy.

  11. Assessing intervention efficacy on high-risk drinkers using generalized linear mixed models with a new class of link functions.

    PubMed

    Prates, Marcos O; Aseltine, Robert H; Dey, Dipak K; Yan, Jun

    2013-11-01

    Unhealthy alcohol use is one of the leading causes of morbidity and mortality in the United States. Brief interventions with high-risk drinkers during an emergency department (ED) visit are of great interest due to their possible efficacy and low cost. In a collaborative study with patients recruited at 14 academic ED across the United States, we examined the self-reported number of drinks per week by each patient following the exposure to a brief intervention. Count data with overdispersion have been mostly analyzed with generalized linear mixed models (GLMMs), of which only a limited number of link functions are available. Different choices of link function provide different fit and predictive power for a particular dataset. We propose a class of link functions from an alternative way to incorporate random effects in a GLMM, which encompasses many existing link functions as special cases. The methodology is naturally implemented in a Bayesian framework, with competing links selected with Bayesian model selection criteria such as the conditional predictive ordinate (CPO). In application to the ED intervention study, all models suggest that the intervention was effective in reducing the number of drinks, but some new models are found to significantly outperform the traditional model as measured by CPO. The validity of CPO in link selection is confirmed in a simulation study that shared the same characteristics as the count data from high-risk drinkers. The dataset and the source code for the best fitting model are available in Supporting Information.

  12. The overlooked potential of generalized linear models in astronomy - III. Bayesian negative binomial regression and globular cluster populations

    NASA Astrophysics Data System (ADS)

    de Souza, R. S.; Hilbe, J. M.; Buelens, B.; Riggs, J. D.; Cameron, E.; Ishida, E. E. O.; Chies-Santos, A. L.; Killedar, M.

    2015-10-01

    In this paper, the third in a series illustrating the power of generalized linear models (GLMs) for the astronomical community, we elucidate the potential of the class of GLMs which handles count data. The size of a galaxy's globular cluster (GC) population (NGC) is a prolonged puzzle in the astronomical literature. It falls in the category of count data analysis, yet it is usually modelled as if it were a continuous response variable. We have developed a Bayesian negative binomial regression model to study the connection between NGC and the following galaxy properties: central black hole mass, dynamical bulge mass, bulge velocity dispersion and absolute visual magnitude. The methodology introduced herein naturally accounts for heteroscedasticity, intrinsic scatter, errors in measurements in both axes (either discrete or continuous) and allows modelling the population of GCs on their natural scale as a non-negative integer variable. Prediction intervals of 99 per cent around the trend for expected NGC comfortably envelope the data, notably including the Milky Way, which has hitherto been considered a problematic outlier. Finally, we demonstrate how random intercept models can incorporate information of each particular galaxy morphological type. Bayesian variable selection methodology allows for automatically identifying galaxy types with different productions of GCs, suggesting that on average S0 galaxies have a GC population 35 per cent smaller than other types with similar brightness.

  13. Acute toxicity of ammonia (NH3-N) in sewage effluent to Chironomus riparius: II. Using a generalized linear model

    USGS Publications Warehouse

    Monda, D.P.; Galat, D.L.; Finger, S.E.; Kaiser, M.S.

    1995-01-01

    Toxicity of un-ionized ammonia (NH3-N) to the midge, Chironomus riparius was compared, using laboratory culture (well) water and sewage effluent (≈0.4 mg/L NH3-N) in two 96-h, static-renewal toxicity experiments. A generalized linear model was used for data analysis. For the first and second experiments, respectively, LC50 values were 9.4 mg/L (Test 1A) and 6.6 mg/L (Test 2A) for ammonia in well water, and 7.8 mg/L (Test 1B) and 4.1 mg/L (Test 2B) for ammonia in sewage effluent. Slopes of dose-response curves for Tests 1A and 2A were equal, but mortality occurred at lower NH3-N concentrations in Test 2A (unequal intercepts). Response ofC. riparius to NH3 in effluent was not consistent; dose-response curves for tests 1B and 2B differed in slope and intercept. Nevertheless, C. riparius was more sensitive to ammonia in effluent than in well water in both experiments, indicating a synergistic effect of ammonia in sewage effluent. These results demonstrate the advantages of analyzing the organisms entire range of response, as opposed to generating LC50 values, which represent only one point on the dose-response curve.

  14. Towards obtaining spatiotemporally precise responses to continuous sensory stimuli in humans: a general linear modeling approach to EEG.

    PubMed

    Gonçalves, Nuno R; Whelan, Robert; Foxe, John J; Lalor, Edmund C

    2014-08-15

    Noninvasive investigation of human sensory processing with high temporal resolution typically involves repeatedly presenting discrete stimuli and extracting an average event-related response from scalp recorded neuroelectric or neuromagnetic signals. While this approach is and has been extremely useful, it suffers from two drawbacks: a lack of naturalness in terms of the stimulus and a lack of precision in terms of the cortical response generators. Here we show that a linear modeling approach that exploits functional specialization in sensory systems can be used to rapidly obtain spatiotemporally precise responses to complex sensory stimuli using electroencephalography (EEG). We demonstrate the method by example through the controlled modulation of the contrast and coherent motion of visual stimuli. Regressing the data against these modulation signals produces spatially focal, highly temporally resolved response measures that are suggestive of specific activation of visual areas V1 and V6, respectively, based on their onset latency, their topographic distribution and the estimated location of their sources. We discuss our approach by comparing it with fMRI/MRI informed source analysis methods and, in doing so, we provide novel information on the timing of coherent motion processing in human V6. Generalizing such an approach has the potential to facilitate the rapid, inexpensive spatiotemporal localization of higher perceptual functions in behaving humans.

  15. Projected changes in precipitation and temperature over the Canadian Prairie Provinces using the Generalized Linear Model statistical downscaling approach

    NASA Astrophysics Data System (ADS)

    Asong, Z. E.; Khaliq, M. N.; Wheater, H. S.

    2016-08-01

    In this study, a multisite multivariate statistical downscaling approach based on the Generalized Linear Model (GLM) framework is developed to downscale daily observations of precipitation and minimum and maximum temperatures from 120 sites located across the Canadian Prairie Provinces: Alberta, Saskatchewan and Manitoba. First, large scale atmospheric covariates from the National Center for Environmental Prediction (NCEP) Reanalysis-I, teleconnection indices, geographical site attributes, and observed precipitation and temperature records are used to calibrate GLMs for the 1971-2000 period. Then the calibrated models are used to generate daily sequences of precipitation and temperature for the 1962-2005 historical (conditioned on NCEP predictors), and future period (2006-2100) using outputs from five CMIP5 (Coupled Model Intercomparison Project Phase-5) Earth System Models corresponding to Representative Concentration Pathway (RCP): RCP2.6, RCP4.5, and RCP8.5 scenarios. The results indicate that the fitted GLMs are able to capture spatiotemporal characteristics of observed precipitation and temperature fields. According to the downscaled future climate, mean precipitation is projected to increase in summer and decrease in winter while minimum temperature is expected to warm faster than the maximum temperature. Climate extremes are projected to intensify with increased radiative forcing.

  16. Complex-number representation of informed basis functions in general linear modeling of Functional Magnetic Resonance Imaging.

    PubMed

    Wang, Pengwei; Wang, Zhishun; He, Lianghua

    2012-03-30

    Functional Magnetic Resonance Imaging (fMRI), measuring Blood Oxygen Level-Dependent (BOLD), is a widely used tool to reveal spatiotemporal pattern of neural activity in human brain. Standard analysis of fMRI data relies on a general linear model and the model is constructed by convolving the task stimuli with a hypothesized hemodynamic response function (HRF). To capture possible phase shifts in the observed BOLD response, the informed basis functions including canonical HRF and its temporal derivative, have been proposed to extend the hypothesized hemodynamic response in order to obtain a good fitting model. Different t contrasts are constructed from the estimated model parameters for detecting the neural activity between different task conditions. However, the estimated model parameters corresponding to the orthogonal basis functions have different physical meanings. It remains unclear how to combine the neural features detected by the two basis functions and construct t contrasts for further analyses. In this paper, we have proposed a novel method for representing multiple basis functions in complex domain to model the task-driven fMRI data. Using this method, we can treat each pair of model parameters, corresponding respectively to canonical HRF and its temporal derivative, as one complex number for each task condition. Using the specific rule we have defined, we can conveniently perform arithmetical operations on the estimated model parameters and generate different t contrasts. We validate this method using the fMRI data acquired from twenty-two healthy participants who underwent an auditory stimulation task.

  17. Depth-compensated diffuse optical tomography enhanced by general linear model analysis and an anatomical atlas of human head.

    PubMed

    Tian, Fenghua; Liu, Hanli

    2014-01-15

    One of the main challenges in functional diffuse optical tomography (DOT) is to accurately recover the depth of brain activation, which is even more essential when differentiating true brain signals from task-evoked artifacts in the scalp. Recently, we developed a depth-compensated algorithm (DCA) to minimize the depth localization error in DOT. However, the semi-infinite model that was used in DCA deviated significantly from the realistic human head anatomy. In the present work, we incorporated depth-compensated DOT (DC-DOT) with a standard anatomical atlas of human head. Computer simulations and human measurements of sensorimotor activation were conducted to examine and prove the depth specificity and quantification accuracy of brain atlas-based DC-DOT. In addition, node-wise statistical analysis based on the general linear model (GLM) was also implemented and performed in this study, showing the robustness of DC-DOT that can accurately identify brain activation at the correct depth for functional brain imaging, even when co-existing with superficial artifacts.

  18. The Effectiveness of an Electronic Student Response System in Teaching Biology to the Non-Major Utilizing Nine Group-Paced, Linear Programs.

    ERIC Educational Resources Information Center

    Bessler, William Carl

    This paper presents the procedures, results, and conclusions of a study designed to determine the effectiveness of an electronic student response system in teaching biology to the non-major. Nine group-paced linear programs were used. Subjects were 664 college students divided into treatment and control groups. The effectiveness of the response…

  19. Influence of a dichlophenyl group on the geometric structure, electronic properties, and static linear polarizability of La at C{sub 74}

    SciTech Connect

    Tang Chunmei; Deng Kaiming; Tan Weishi; Yuan Yongbo; Liu Yuzhen; Wu Haiping; Huang Decai; Hu Fenglan; Yang Jinlong; Wang Xin

    2007-07-15

    The generalized gradient approximation based on density functional theory is used to study which effects are brought by the dichlophenyl group C{sub 6}H{sub 3}Cl{sub 2} on the geometric structure, electronic properties, and static linear polarizability of La at C{sub 74}. It is found that the most favorable endohedral site of a La atom in La at C{sub 74}, similar to the cases of Ca at C{sub 74} and Eu at C{sub 74}, is off-center under a [6, 6] double bond along the C{sub 2} axis on the {sigma}{sub h} plane, yielding a structure marked as La at C{sub 74}-2. It is interesting that the La at C{sub 74} molecule has 1{mu}{sub B} magnetic moment, while La at C{sub 74}(C{sub 6}H{sub 3}Cl{sub 2}) has a closed-shell electronic structure. With respect to the static linear polarizability, La at C{sub 74}-2 has a nonzero value only in the positive z direction 679.6 A{sup 3} and shows a giant anisotropic polarizability due to its low C{sub 2v}-symmetric structure in contrast to the isotropic polarizability of C{sub 60} with I{sub h}-symmetric structure as well as the transference of about three electrons from the La atom to the carbon cage. However, the three components along the x, y, and z directions for La at C{sub 74}(C{sub 6}H{sub 3}Cl{sub 2}) are, respectively, 998.7, 821.4, and 710.3 A{sup 3} with the mean value 843.5 A{sup 3}, much larger than that of La at C{sub 74}-2. The static linear polarizability anisotropy of La at C{sub 74}(C{sub 6}H{sub 3}Cl{sub 2}) 251.9 A{sup 3} is much smaller than that of La at C{sub 74} 679.6 A{sup 3} because the inclined dichlorophenyl group completely destroys the C{sub 2v} symmetry of La at C{sub 74}-2.

  20. Performance of meta-GGA Functionals on General Main Group Thermochemistry, Kinetics, and Noncovalent Interactions.

    PubMed

    Hao, Pan; Sun, Jianwei; Xiao, Bing; Ruzsinszky, Adrienn; Csonka, Gábor I; Tao, Jianmin; Glindmeyer, Stephen; Perdew, John P

    2013-01-08

    Among the computationally efficient semilocal density functionals for the exchange-correlation energy, meta-generalized-gradient approximations (meta-GGAs) are potentially the most accurate. Here, we assess the performance of three new meta-GGAs (revised Tao-Perdew-Staroverov-Scuseria or revTPSS, regularized revTPSS or regTPSS, and meta-GGA made simple or MGGA_MS), within and beyond their "comfort zones," on Grimme's big test set of main-group molecular energetics (thermochemistry, kinetics, and noncovalent interactions). We compare them against the standard Perdew-Burke-Ernzerhof (PBE) GGA, TPSS, and Minnesota M06L meta-GGAs, and Becke-3-Lee-Yang-Parr (B3LYP) hybrid of GGA with exact exchange. The overall performance of these three new meta-GGA functionals is similar. However, dramatic differences occur for different test sets. For example, M06L and MGGA_MS perform best for the test sets that contain noncovalent interactions. For the 14 Diels-Alder reaction energies in the "difficult" DARC subset, the mean absolute error ranges from 3 kcal mol(-1) (MGGA_MS) to 15 kcal mol(-1) (B3LYP), while for some other reaction subsets the order of accuracy is reversed; more generally, the tested new semilocal functionals outperform the standard B3LYP for ring reactions. Some overall improvement is found from long-range dispersion corrections for revTPSS and regTPSS but not for MGGA_MS. Formal and universality criteria for the functionals are also discussed.

  1. Kalman estimator- and general linear model-based on-line brain activation mapping by near-infrared spectroscopy

    PubMed Central

    2010-01-01

    Background Near-infrared spectroscopy (NIRS) is a non-invasive neuroimaging technique that recently has been developed to measure the changes of cerebral blood oxygenation associated with brain activities. To date, for functional brain mapping applications, there is no standard on-line method for analysing NIRS data. Methods In this paper, a novel on-line NIRS data analysis framework taking advantages of both the general linear model (GLM) and the Kalman estimator is devised. The Kalman estimator is used to update the GLM coefficients recursively, and one critical coefficient regarding brain activities is then passed to a t-statistical test. The t-statistical test result is used to update a topographic brain activation map. Meanwhile, a set of high-pass filters is plugged into the GLM to prevent very low-frequency noises, and an autoregressive (AR) model is used to prevent the temporal correlation caused by physiological noises in NIRS time series. A set of data recorded in finger tapping experiments is studied using the proposed framework. Results The obtained results suggest that the method can effectively track the task related brain activation areas, and prevent the noise distortion in the estimation while the experiment is running. Thereby, the potential of the proposed method for real-time NIRS-based brain imaging was demonstrated. Conclusions This paper presents a novel on-line approach for analysing NIRS data for functional brain mapping applications. This approach demonstrates the potential of a real-time-updating topographic brain activation map. PMID:21138595

  2. Statistical Downscaling of Seasonal Forecasts and Climate Change Scenarios using Generalized Linear Modeling Approach for Stochastic Weather Generators

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Katz, R. W.; Rajagopalan, B.; Podesta, G. P.

    2009-12-01

    Climate forecasts and climate change scenarios are typically provided in the form of monthly or seasonally aggregated totals or means. But time series of daily weather (e.g., precipitation amount, minimum and maximum temperature) are commonly required for use in agricultural decision-making. Stochastic weather generators constitute one technique to temporally downscale such climate information. The recently introduced approach for stochastic weather generators, based generalized linear modeling (GLM), is convenient for this purpose, especially with covariates to account for seasonality and teleconnections (e.g., with the El Niño phenomenon). Yet one important limitation of stochastic weather generators is a marked tendency to underestimate the observed interannual variance of seasonally aggregated variables. To reduce this “overdispersion” phenomenon, we incorporate time series of seasonal total precipitation and seasonal mean minimum and maximum temperature in the GLM weather generator as covariates. These seasonal time series are smoothed using locally weighted scatterplot smoothing (LOESS) to avoid introducing underdispersion. Because the aggregate variables appear explicitly in the weather generator, downscaling to daily sequences can be readily implemented. The proposed method is applied to time series of daily weather at Pergamino and Pilar in the Argentine Pampas. Seasonal precipitation and temperature forecasts produced by the International Research Institute for Climate and Society (IRI) are used as prototypes. In conjunction with the GLM weather generator, a resampling scheme is used to translate the uncertainty in the seasonal forecasts (the IRI format only specifies probabilities for three categories: below normal, near normal, and above normal) into the corresponding uncertainty for the daily weather statistics. The method is able to generate potentially useful shifts in the probability distributions of seasonally aggregated precipitation and

  3. Power and Sample Size Calculations for Testing Linear Combinations of Group Means under Variance Heterogeneity with Applications to Meta and Moderation Analyses

    ERIC Educational Resources Information Center

    Shieh, Gwowen; Jan, Show-Li

    2015-01-01

    The general formulation of a linear combination of population means permits a wide range of research questions to be tested within the context of ANOVA. However, it has been stressed in many research areas that the homogeneous variances assumption is frequently violated. To accommodate the heterogeneity of variance structure, the…

  4. Symposium on General Linear Model Approach to the Analysis of Experimental Data in Educational Research (Athens, Georgia, June 29-July 1, 1967). Final Report.

    ERIC Educational Resources Information Center

    Bashaw, W. L., Ed.; Findley, Warren G., Ed.

    This volume contains the five major addresses and subsequent discussion from the Symposium on the General Linear Models Approach to the Analysis of Experimental Data in Educational Research, which was held in 1967 in Athens, Georgia. The symposium was designed to produce systematic information, including new methodology, for dissemination to the…

  5. Developing a Measure of General Academic Ability: An Application of Maximal Reliability and Optimal Linear Combination to High School Students' Scores

    ERIC Educational Resources Information Center

    Dimitrov, Dimiter M.; Raykov, Tenko; AL-Qataee, Abdullah Ali

    2015-01-01

    This article is concerned with developing a measure of general academic ability (GAA) for high school graduates who apply to colleges, as well as with the identification of optimal weights of the GAA indicators in a linear combination that yields a composite score with maximal reliability and maximal predictive validity, employing the framework of…

  6. Generalization of Muscle Strength Capacities as Assessed From Different Variables, Tests, and Muscle Groups.

    PubMed

    Cuk, Ivan; Prebeg, Goran; Sreckovic, Sreten; Mirkov, Dragan M; Jaric, Slobodan

    2017-02-01

    Cuk, I, Prebeg, G, Sreckovic, S, Mirkov, DM, and Jaric, S. Generalization of muscle strength capacities as assessed from different variables, tests, and muscle groups. J Strength Cond Res 31(2): 305-312, 2017-The muscle strength capacities to exert force under various movement conditions have been indiscriminately assessed from various strength tests and variables applied on different muscles. We tested the hypotheses that the distinctive strength capacities would be revealed (H1) through different strength tests, and (H2) through different strength variables. Alternatively, (H3) all strength variables independent of the selected test could depict the same strength capacity of the tested muscle. Sixty subjects performed both the standard strength test and the test of alternating contractions of 6 pairs of antagonistic muscles acting in different leg and arm joints. The dependent variables obtained from each test and muscle were the maximum isometric force and the rate of force development. A confirmatory principle component analysis set to 2 factors explained 31.9% of the total variance. The factor loadings discerned between the tested arm and leg muscles, but not between the strength tests and variables. An exploratory analysis applied on the same data revealed 6 factors that explained 60.1% of the total variance. Again, the individual factors were mainly loaded by different tests and variables obtained from the same pair of antagonistic muscles. Therefore, a comprehensive assessment of the muscle strength capacity of the tested individual should be based on a single strength test and variable obtained from a number of different muscles, than on a single muscle tested through different tests and variables. The selected muscles should act in different limbs and joints, while the maximum isometric force should be the variable of choice.

  7. Alcohol Habits in Patients with Long-Term Musculoskeletal Pain: Comparison with a Matched Control Group from the General Population

    ERIC Educational Resources Information Center

    Thelin Bronner, Kerstin Birgitta; Wennberg, Peter; Kallmen, Hakan; Schult, Marie-Louise Birgitta

    2012-01-01

    This prospective study aimed to describe alcohol habits in patients with chronic pain compared with those in a matched control group from the general Swedish population. In total, 100 consecutive patients enrolled were matched against 100 individuals in a control group on the basis of age and sex. Alcohol habits were measured using the Alcohol Use…

  8. Symmetry Groups and New Exact Solutions to (2+1)-Dimensional Variable Coefficient Canonical Generalized KP Equation

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Hua; Liu, Xi-Qiang; Bai, Cheng-Lin

    2007-09-01

    In this paper, the modified CK's direct method to find symmetry groups of nonlinear partial differential equation is extended to (2+1)-dimensional variable coefficient canonical generalized KP (VCCGKP) equation. As a result, symmetry groups, Lie point symmetry group and Lie symmetry for the VCCGKP equation are obtained. In fact, the Lie point symmetry group coincides with that obtained by the standard Lie group approach. Applying the given Lie symmetry, we obtain five types of similarity reductions and a lot of new exact solutions, including hyperbolic function solutions, triangular periodic solutions, Jacobi elliptic function solutions and rational solutions, for the VCCGKP equation.

  9. A Comparison of Four Linear Equating Methods for the Common-Item Nonequivalent Groups Design Using Simulation Methods. ACT Research Report Series, 2013 (2)

    ERIC Educational Resources Information Center

    Topczewski, Anna; Cui, Zhongmin; Woodruff, David; Chen, Hanwei; Fang, Yu

    2013-01-01

    This paper investigates four methods of linear equating under the common item nonequivalent groups design. Three of the methods are well known: Tucker, Angoff-Levine, and Congeneric-Levine. A fourth method is presented as a variant of the Congeneric-Levine method. Using simulation data generated from the three-parameter logistic IRT model we…

  10. Scalar-Tensor gravity with system-dependent potential and its relation with Renormalization Group extended General Relativity

    SciTech Connect

    Rodrigues, Davi C.; Piattella, Oliver F.; Chauvineau, Bertrand E-mail: Bertrand.Chauvineau@oca.eu

    2015-09-01

    We show that Renormalization Group extensions of the Einstein-Hilbert action for large scale physics are not, in general, a particular case of standard Scalar-Tensor (ST) gravity. We present a new class of ST actions, in which the potential is not necessarily fixed at the action level, and show that this extended ST theory formally contains the Renormalization Group case. We also propose here a Renormalization Group scale setting identification that is explicitly covariant and valid for arbitrary relativistic fluids.

  11. An Alternative to Ancova When Group Regressions are Heterogeneous: The Generalized Johnson-Neyman Procedure.

    ERIC Educational Resources Information Center

    Forster, Fred

    The purpose of this study was to develop the Johnson-Neyman Procedure (JN-Procedure) appropriate to multiple groups and covariables, and demonstrate its use in the analysis of group differences. A sequence of significance tests which makes it possible to identify the most parsimonious analysis of group differences appropriate to a given set of…

  12. A generating set direct search augmented Lagrangian algorithm for optimization with a combination of general and linear constraints.

    SciTech Connect

    Lewis, Robert Michael (College of William and Mary, Williamsburg, VA); Torczon, Virginia Joanne (College of William and Mary, Williamsburg, VA); Kolda, Tamara Gibson

    2006-08-01

    We consider the solution of nonlinear programs in the case where derivatives of the objective function and nonlinear constraints are unavailable. To solve such problems, we propose an adaptation of a method due to Conn, Gould, Sartenaer, and Toint that proceeds by approximately minimizing a succession of linearly constrained augmented Lagrangians. Our modification is to use a derivative-free generating set direct search algorithm to solve the linearly constrained subproblems. The stopping criterion proposed by Conn, Gould, Sartenaer and Toint for the approximate solution of the subproblems requires explicit knowledge of derivatives. Such information is presumed absent in the generating set search method we employ. Instead, we show that stationarity results for linearly constrained generating set search methods provide a derivative-free stopping criterion, based on a step-length control parameter, that is sufficient to preserve the convergence properties of the original augmented Lagrangian algorithm.

  13. The 'heartsink' patient revisited. The Welsh Philosophy And General Practice discussion Group.

    PubMed Central

    Butler, C C; Evans, M

    1999-01-01

    The term 'heartsink patient' is now part of the vocabulary of general practice. But what and where is the heartsink? How should the phenomenon be studied? What are the implications of differing interpretations for general practice? The heartsink patient presents personal, social, and soteriological (pertaining to salvation) problems in physical terms. This poses a fundamental challenge to the philosophical foundations of general practice. Emphasizing a biomedical role justifies questioning the legitimacy of 'heartsinks' as patients. Alternatively, general practice should reassert its acceptance of suffering, whatever its origin and presentation. This would justify accommodating a far greater range of problems than simply those explained by biomedicine alone, and make general practice soteriological to the core. PMID:10343431

  14. Patterns, Quantities, and Linear Functions

    ERIC Educational Resources Information Center

    Ellis, Amy B.

    2009-01-01

    Pattern generalization and a focus on quantities are important aspects of algebraic reasoning. This article describes two different approaches to teaching and learning linear functions for middle school students. One group focused on patterns in number tables, and the other group worked primarily with real-world quantities. This article highlights…

  15. Functional specialization and generalization for grouping of stimuli based on colour and motion

    PubMed Central

    Zeki, Semir; Stutters, Jonathan

    2013-01-01

    This study was undertaken to learn whether the principle of functional specialization that is evident at the level of the prestriate visual cortex extends to areas that are involved in grouping visual stimuli according to attribute, and specifically according to colour and motion. Subjects viewed, in an fMRI scanner, visual stimuli composed of moving dots, which could be either coloured or achromatic; in some stimuli the moving coloured dots were randomly distributed or moved in random directions; in others, some of the moving dots were grouped together according to colour or to direction of motion, with the number of groupings varying from 1 to 3. Increased activation was observed in area V4 in response to colour grouping and in V5 in response to motion grouping while both groupings led to activity in separate though contiguous compartments within the intraparietal cortex. The activity in all the above areas was parametrically related to the number of groupings, as was the prominent activity in Crus I of the cerebellum where the activity resulting from the two types of grouping overlapped. This suggests (a) that, the specialized visual areas of the prestriate cortex have functions beyond the processing of visual signals according to attribute, namely that of grouping signals according to colour (V4) or motion (V5); (b) that the functional separation evident in visual cortical areas devoted to motion and colour, respectively, is maintained at the level of parietal cortex, at least as far as grouping according to attribute is concerned; and (c) that, by contrast, this grouping-related functional segregation is not maintained at the level of the cerebellum. PMID:23415950

  16. ELAS: A general-purpose computer program for the equilibrium problems of linear structures. Volume 2: Documentation of the program. [subroutines and flow charts

    NASA Technical Reports Server (NTRS)

    Utku, S.

    1969-01-01

    A general purpose digital computer program for the in-core solution of linear equilibrium problems of structural mechanics is documented. The program requires minimum input for the description of the problem. The solution is obtained by means of the displacement method and the finite element technique. Almost any geometry and structure may be handled because of the availability of linear, triangular, quadrilateral, tetrahedral, hexahedral, conical, triangular torus, and quadrilateral torus elements. The assumption of piecewise linear deflection distribution insures monotonic convergence of the deflections from the stiffer side with decreasing mesh size. The stresses are provided by the best-fit strain tensors in the least squares at the mesh points where the deflections are given. The selection of local coordinate systems whenever necessary is automatic. The core memory is used by means of dynamic memory allocation, an optional mesh-point relabelling scheme and imposition of the boundary conditions during the assembly time.

  17. 75 FR 41521 - Delphi Corporation, Automotive Holding Group, Plant 6, Currently Known as General Motors...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-16

    ... Chemicals, Interim Physicians, LLC and HSS Material Management, Flint, MI; Delphi Corporation, Automotive..., Flint, MI; Amended Certification Regarding Eligibility To Apply for Worker Adjustment Assistance and..., Flint, Michigan and Delphi Corporation, Automotive Holding Group, Plant 2, including on-site...

  18. Teaching Is Learning--Maximum Incentive, Minimum Discipline in Student Groups Teaching General Chemistry.

    ERIC Educational Resources Information Center

    Benvenuto, Mark

    2001-01-01

    Presents a teaching approach that uses student group teaching wherein students teach, are rewarded for good performance and benefit from other students' academic achievement during quizzes. Discusses the scope and limitations of this approach. Includes 15 references. (YDS)

  19. Accuracy assessment of the linear Poisson-Boltzmann equation and reparametrization of the OBC generalized Born model for nucleic acids and nucleic acid-protein complexes.

    PubMed

    Fogolari, Federico; Corazza, Alessandra; Esposito, Gennaro

    2015-04-05

    The generalized Born model in the Onufriev, Bashford, and Case (Onufriev et al., Proteins: Struct Funct Genet 2004, 55, 383) implementation has emerged as one of the best compromises between accuracy and speed of computation. For simulations of nucleic acids, however, a number of issues should be addressed: (1) the generalized Born model is based on a linear model and the linearization of the reference Poisson-Boltmann equation may be questioned for highly charged systems as nucleic acids; (2) although much attention has been given to potentials, solvation forces could be much less sensitive to linearization than the potentials; and (3) the accuracy of the Onufriev-Bashford-Case (OBC) model for nucleic acids depends on fine tuning of parameters. Here, we show that the linearization of the Poisson Boltzmann equation has mild effects on computed forces, and that with optimal choice of the OBC model parameters, solvation forces, essential for molecular dynamics simulations, agree well with those computed using the reference Poisson-Boltzmann model.

  20. Change in attachment to the therapy group generalizes to change in individual attachment among women with binge eating disorder.

    PubMed

    Keating, Leah; Tasca, Giorgio A; Gick, Mary; Ritchie, Kerri; Balfour, Louise; Bissada, Hany

    2014-03-01

    Attachment to groups is analogous to attachment to individuals, and may play an important role in group functioning and in group psychotherapy outcomes. This study examined whether attachment to the therapy group can change during treatment, and whether such change predicts improvements in treatment outcomes, including individual attachment, up to 1 year posttreatment. Eighty-seven women with binge eating disorder (BED) attended Group Psychodynamic Interpersonal Psychotherapy (GPIP). Participants were assigned to one of two conditions in which groups were homogeneously composed of women with either higher or lower individual attachment anxiety. Outcomes were assessed pre, post, 6 months, and 1 year posttreatment. Attachment to the group was assessed at weeks 4, 8, 12, and 16 of GPIP. Group attachment insecurity decreased significantly during treatment. Reductions in group attachment avoidance predicted decreases in individual attachment insecurity at 1 year posttreatment. Study condition did not moderate these associations. These results indicate that women with BED who receive GPIP are able to generalize improvements in group attachment security to their individual attachment relationships outside of therapy up to 1 year post group treatment.

  1. An Investigation of the General Abilities Index in a Group of Diagnostically Mixed Patients

    ERIC Educational Resources Information Center

    Harrison, Allyson G.; DeLisle, Michelle M.; Parker, Kevin C. H.

    2008-01-01

    The General Ability Index (GAI) was compared with Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) Full Scale Intelligence Quotient (FSIQ) from the WAIS-III in data obtained from 381 adults assessed for reported learning or attention problems between 1998 and 2005. Not only did clients with more neurocognitively based disorders (i.e.,…

  2. Group classification and conservation laws of the generalized Klein-Gordon-Fock equation

    NASA Astrophysics Data System (ADS)

    Muatjetjeja, B.

    2016-08-01

    In the present paper, we perform Lie and Noether symmetries of the generalized Klein-Gordon-Fock equation. It is shown that the principal Lie algebra, which is one-dimensional, has several possible extensions. It is further shown that several cases arise for which Noether symmetries exist. Exact solutions for some cases are also obtained from the invariant solutions of the investigated equation.

  3. [Photophoresis and mesophotophoresis of angioprotectant group preparations for comprehensive treatment of patients with chronic generalized parodontitis].

    PubMed

    Prikuls, V F

    2008-01-01

    Examination of 118 patients with chronic generalized parodontitis of medium and heavy severity was performed and treatment was elaborated with the use of laser therapy and angioprotectants' photophoresis and mesophotophoresis. Use of the mentioned physical and physical-pharmacological methods in comprehensive cure let to shorten the course of treatment and increase remission duration.

  4. An Exploratory Study of the Application of Generalized Inverse to ILS Estimation of Overidentified Equations in Linear Models

    DTIC Science & Technology

    1975-04-15

    paper is a compromise in the same nature as the 2SLS. We use the Moore - Penrose (MP) generalized inverse to... Moore - Penrose generalized inverse ; Indirect Least Squares; 1’wo Stage Least Squares; Instrumental Variables; Limited Information Maximum L-..clihood...Abstract -In this paper , we propose a procedure based on the use of the Moore - Penrose inverse of matrices for deriving unique Indirect Least Squares

  5. The Factorial Validity of The Maslach Burnout Inventory--General Survey in Representative Samples of Eight Different Occupational Groups

    ERIC Educational Resources Information Center

    Langballe, Ellen Melbye; Falkum, Erik; Innstrand, Siw Tone; Aasland, Olaf Gjerlow

    2006-01-01

    The Maslach Burnout Inventory--General Survey (MBI-GS) is designed to measure the three subdimensions (exhaustion, cynicism, and professional efficacy) of burnout in a wide range of occupations. This article examines the factorial validity of the MBI-GS across eight different occupational groups in Norway: lawyers, physicians, nurses, teachers,…

  6. Cultural Similarities in Perfectionism: Perfectionistic Strivings and Concerns Generalize across Chinese and Canadian Groups

    ERIC Educational Resources Information Center

    Smith, Martin M.; Saklofske, Donald H.; Yan, Gonggu; Sherry, Simon B.

    2016-01-01

    This study supports the generalizability of perfectionistic strivings and concerns across Canadian and Chinese university students (N = 1,006) and demonstrates the importance of establishing measurement invariance prior to hypothesis testing with different groups. No latent mean difference in perfectionistic concerns was observed, but Canadian…

  7. Using Interdependent Group-Oriented Reinforcement to Enhance Academic Performance in General Education Classrooms

    ERIC Educational Resources Information Center

    Skinner, Christopher H.; Williams, Robert L.; Neddenriep, Christine E.

    2004-01-01

    In their meta-analysis, Stage and Quiroz (1997) found that group-oriented contingencies yielded the largest effect size of interventions designed to reduce inappropriate behaviors in public schools. However, such procedures may be underutilized for enhancing academic performance and learning. The current article describes how interdependent…

  8. Multiple Linear Regressions by Maximizing the Likelihood under Assumption of Generalized Gauss-Laplace Distribution of the Error

    PubMed Central

    Jäntschi, Lorentz

    2016-01-01

    Multiple linear regression analysis is widely used to link an outcome with predictors for better understanding of the behaviour of the outcome of interest. Usually, under the assumption that the errors follow a normal distribution, the coefficients of the model are estimated by minimizing the sum of squared deviations. A new approach based on maximum likelihood estimation is proposed for finding the coefficients on linear models with two predictors without any constrictive assumptions on the distribution of the errors. The algorithm was developed, implemented, and tested as proof-of-concept using fourteen sets of compounds by investigating the link between activity/property (as outcome) and structural feature information incorporated by molecular descriptors (as predictors). The results on real data demonstrated that in all investigated cases the power of the error is significantly different by the convenient value of two when the Gauss-Laplace distribution was used to relax the constrictive assumption of the normal distribution of the error. Therefore, the Gauss-Laplace distribution of the error could not be rejected while the hypothesis that the power of the error from Gauss-Laplace distribution is normal distributed also failed to be rejected. PMID:28090215

  9. Multiple Linear Regressions by Maximizing the Likelihood under Assumption of Generalized Gauss-Laplace Distribution of the Error.

    PubMed

    Jäntschi, Lorentz; Bálint, Donatella; Bolboacă, Sorana D

    2016-01-01

    Multiple linear regression analysis is widely used to link an outcome with predictors for better understanding of the behaviour of the outcome of interest. Usually, under the assumption that the errors follow a normal distribution, the coefficients of the model are estimated by minimizing the sum of squared deviations. A new approach based on maximum likelihood estimation is proposed for finding the coefficients on linear models with two predictors without any constrictive assumptions on the distribution of the errors. The algorithm was developed, implemented, and tested as proof-of-concept using fourteen sets of compounds by investigating the link between activity/property (as outcome) and structural feature information incorporated by molecular descriptors (as predictors). The results on real data demonstrated that in all investigated cases the power of the error is significantly different by the convenient value of two when the Gauss-Laplace distribution was used to relax the constrictive assumption of the normal distribution of the error. Therefore, the Gauss-Laplace distribution of the error could not be rejected while the hypothesis that the power of the error from Gauss-Laplace distribution is normal distributed also failed to be rejected.

  10. Multivariate General Linear Models (MGLM) on Riemannian Manifolds with Applications to Statistical Analysis of Diffusion Weighted Images

    PubMed Central

    Kim, Hyunwoo J.; Adluru, Nagesh; Collins, Maxwell D.; Chung, Moo K.; Bendlin, Barbara B.; Johnson, Sterling C.; Davidson, Richard J.; Singh, Vikas

    2014-01-01

    Linear regression is a parametric model which is ubiquitous in scientific analysis. The classical setup where the observations and responses, i.e., (xi, yi) pairs, are Euclidean is well studied. The setting where yi is manifold valued is a topic of much interest, motivated by applications in shape analysis, topic modeling, and medical imaging. Recent work gives strategies for max-margin classifiers, principal components analysis, and dictionary learning on certain types of manifolds. For parametric regression specifically, results within the last year provide mechanisms to regress one real-valued parameter, xi ∈ R, against a manifold-valued variable, yi ∈ . We seek to substantially extend the operating range of such methods by deriving schemes for multivariate multiple linear regression —a manifold-valued dependent variable against multiple independent variables, i.e., f : Rn → . Our variational algorithm efficiently solves for multiple geodesic bases on the manifold concurrently via gradient updates. This allows us to answer questions such as: what is the relationship of the measurement at voxel y to disease when conditioned on age and gender. We show applications to statistical analysis of diffusion weighted images, which give rise to regression tasks on the manifold GL(n)/O(n) for diffusion tensor images (DTI) and the Hilbert unit sphere for orientation distribution functions (ODF) from high angular resolution acquisition. The companion open-source code is available on nitrc.org/projects/riem_mglm. PMID:25580070

  11. Insights of private general practitioners in group practice on the introduction of National Health Insurance in South Africa

    PubMed Central

    Luiz, John; Carmichael, Teresa; Peersman, Wim; Derese, Anselme

    2016-01-01

    Background The South African government intends to contract with ‘accredited provider groups’ for capitated primary care under National Health Insurance (NHI). South African solo general practitioners (GPs) are unhappy with group practice. There is no clarity on the views of GPs in group practice on contracting to the NHI. Objectives To describe the demographic and practice profile of GPs in group practice in South Africa, and evaluate their views on NHI, compared to solo GPs. Methods This was a descriptive survey. The population of 8721 private GPs in South Africa with emails available were emailed an online questionnaire. Descriptive statistical analyses and thematic content analysis were conducted. Results In all, 819 GPs responded (568 solo GPs and 251 GPs in groups). The results are focused on group GPs. GPs in groups have a different demographic practice profile compared to solo GPs. GPs in groups expected R4.86 million ($0.41 million) for a hypothetical NHI proposal of comprehensive primary healthcare (excluding medicines and investigations) to a practice population of 10 000 people. GPs planned a clinical team of 8 to 12 (including nurses) and 4 to 6 administrative staff. GPs in group practices saw three major risks: patient, organisational and government, with three related risk management strategies. Conclusions GPs can competitively contract with NHI, although there are concerns. NHI contracting should not be limited to groups. All GPs embraced strong teamwork, including using nurses more effectively. This aligns well with the emergence of family medicine in Africa. PMID:27380785

  12. A randomized clinical trial comparing general exercise, McKenzie treatment and a control group in patients with neck pain.

    PubMed

    Kjellman, Görel; Oberg, Birgitta

    2002-07-01

    Seventy-seven patients with neck pain in the primary health care were included in a prospective, randomized clinical trial and randomly assigned to general exercise, McKenzie treatment, or a control group. Seventy patients completed the treatment; response rate 93% at 12-month follow-up. All three groups showed significant improvement regarding the main outcomes, pain intensity and Neck Disability Index, even at 12-month follow-up, but there was no significant difference between the groups. In all, 79% reported that they were better or completely restored after treatment, although 51% reported constant/daily pain. In the McKenzie group compared with the control group, a tendency toward greater improvement was noted for pain intensity at 3 weeks and at 6-month follow-up, and for post-treatment Neck Disability Index. Significant improvement in Distress and Risk Assessment Method scores was shown in the McKenzie group only. The three groups had similar recurrence rates, although after 12 months the McKenzie group showed a tendency toward fewer visits for additional health care. The study did not provide a definite evidence of treatment efficacy in patients with neck pain, however, there was a tendency toward a better outcome with the two active alternatives compared with the control group.

  13. Stereocomplex Crystallization of Linear Two-Armed Stereo Diblock Copolymers: Effects of Chain Directional Change, Coinitiator Moiety, and Terminal Groups.

    PubMed

    Tsuji, Hideto; Ogawa, Michiaki; Arakawa, Yuki

    2017-03-30

    Two-armed poly(l-lactide) (PLLA)-b-poly(d-lactide) (PDLA) (2-LD) copolymers with a wide-range of molecular weight were synthesized and the effect of coinitiator moiety, which functions as impurity and causes chain directional change in the middle of molecules (Effect A), and/or the additional effect of types of terminal groups (Effect B) on crystallization behavior of 2-LD copolymers were studied, in comparison with that reported for one-armed PLLA-b-PDLA (1-LD) copolymers. Formation of only stereocomplex (SC) crystallites in 2-LD and 1-LD copolymers indicates that neighboring PLLA and PDLA blocks facilitated SC crystallization and neither Effect A nor B affected the crystalline species. Effect A and/or B (both hydroxyl terminal groups) disturbed cold SC crystallization of 2-LD copolymers compared to that of 1-LD copolymers. Crystalline growth morphologies of 2-LD and 1-LD copolymers during cold SC crystallization were spherical and solid sheaf, respectively, exhibiting that crystalline growth morphology was influenced by Effects A and/or B. The melting temperature or crystalline thickness of SC crystallites were determined by number-average molecular weight per one block and not affected by Effect A or B. Maximum radial growth rates of spherulites of 2-LD copolymers compared to those of 1-LD copolymers were largely decreased by Effect A and/or B (both hydroxyl terminal groups).

  14. a General Algorithm for the Generation of Quasilattices by Means of the Cut and Projection Method Using the SIMPLEX Method of Linear Programming and the Moore-Penrose Generalized Inverse

    NASA Astrophysics Data System (ADS)

    Aragón, J. L.; Vázquez Polo, G.; Gómez, A.

    A computational algorithm for the generation of quasiperiodic tiles based on the cut and projection method is presented. The algorithm is capable of projecting any type of lattice embedded in any euclidean space onto any subspace making it possible to generate quasiperiodic tiles with any desired symmetry. The simplex method of linear programming and the Moore-Penrose generalized inverse are used to construct the cut (strip) in the higher dimensional space which is to be projected.

  15. National asthma attack audit 1991-2. General Practitioners in Asthma Group.

    PubMed Central

    Neville, R G; Clark, R C; Hoskins, G; Smith, B

    1993-01-01

    OBJECTIVE--To describe the frequency and characteristics of asthma attacks in the United Kingdom and to compare actual management with recommended guidelines for the management of attacks. DESIGN--Correspondence survey. SETTING--218 general practices in the United Kingdom. SUBJECTS--1775 patients of all ages who had a total of 1805 asthma attacks over three months. MAIN OUTCOME MEASURES--Patient characteristics, place of management of attacks, comparison of actual management with recommended guidelines. RESULTS--Of the 1805 attacks, 300 occurred in boys aged 0-9, 144 in girls aged 0-9, and 118 in women aged 20-29. The estimated frequency of attacks in the community was 14.3 per 1000 patients per year. 1546 (86%) patients with attacks were managed within general practice, 225 (12%) were admitted to hospital, and 34 (2%) were discharged from an accident and emergency department. Two patients died. On initial presentation, 248 (14%) patients were "not breathless," 900 (50%) were "moderately breathless," 535 (30%) were "breathless and distressed," 68 (4%) were "too breathless to talk," and 2 were "moribund." Recording of clinical data was variable. Underuse of nebulised bronchodilators and systemic steroid was apparent in all grades of clinical severity. Contrary to current guidelines for asthma management, "step up" in maintenance therapy after an attack was often not practised. CONCLUSION--Reported management was at variance with recommended guidelines. This has major implications for the design and distribution of future guidelines. PMID:8461773

  16. Diversity of Methane-Cycling Archaea in Hydrothermal Sediment Investigated by General and Group-Specific PCR Primers

    PubMed Central

    Teske, Andreas P.

    2014-01-01

    The zonation of anaerobic methane-cycling Archaea in hydrothermal sediment of Guaymas Basin was studied by general primer pairs (mcrI, ME1/ME2, mcrIRD) targeting the alpha subunit of methyl coenzyme M reductase gene (mcrA) and by new group-specific mcrA and 16S rRNA gene primer pairs. The mcrIRD primer pair outperformed the other general mcrA primer pairs in detection sensitivity and phylogenetic coverage. Methanotrophic ANME-1 Archaea were the only group detected with group-specific primers only. The detection of 14 mcrA lineages surpasses the diversity previously found in this location. Most phylotypes have high sequence similarities to hydrogenotrophs, methylotrophs, and anaerobic methanotrophs previously detected at Guaymas Basin or at hydrothermal vents, cold seeps, and oil reservoirs worldwide. Additionally, five mcrA phylotypes belonging to newly defined lineages are detected. Two of these belong to deeply branching new orders, while the others are new species or genera of Methanopyraceae and Methermicoccaceae. Downcore diversity decreases from all groups detected in the upper 6 cm (∼2 to 40°C, sulfate measurable to 4 cm) to only two groups below 6 cm (>40°C). Despite the presence of hyperthermophilic genera (Methanopyrus, Methanocaldococcus) in cooler surface strata, no genes were detected below 10 cm (≥60°C). While mcrA-based and 16S rRNA gene-based community compositions are generally congruent, the deeply branching mcrA cannot be assigned to specific 16S rRNA gene lineages. Our study indicates that even among well-studied metabolic groups and in previously characterized model environments, major evolutionary branches are overlooked. Detecting these groups by improved molecular biological methods is a crucial first step toward understanding their roles in nature. PMID:25527539

  17. Diversity of methane-cycling archaea in hydrothermal sediment investigated by general and group-specific PCR primers.

    PubMed

    Lever, Mark A; Teske, Andreas P

    2015-02-01

    The zonation of anaerobic methane-cycling Archaea in hydrothermal sediment of Guaymas Basin was studied by general primerpairs (mcrI, ME1/ME2, mcrIRD) targeting the alpha subunit of methyl coenzyme M reductase gene (mcrA) and by new group specific mcrA and 16S rRNA gene primer pairs. The mcrIRD primer pair outperformed the other general mcrA primer pairs indetection sensitivity and phylogenetic coverage. Methanotrophic ANME-1 Archaea were the only group detected with group specific primers only. The detection of 14 mcrA lineages surpasses the diversity previously found in this location. Most phylotypes have high sequence similarities to hydrogenotrophs, methylotrophs, and anaerobic methanotrophs previously detected at Guaymas Basin or at hydrothermal vents, cold seeps, and oil reservoirs worldwide. Additionally, five mcrA phylotypes belonging to newly defined lineages are detected. Two of these belong to deeply branching new orders, while the others are new species or genera of Methanopyraceae and Methermicoccaceae. Downcore diversity decreases from all groups detected in the upper 6 cm(2 to 40 °C, sulfate measurable to 4 cm) to only two groups below 6 cm (>40 °C). Despite the presence of hyperthermophilic genera (Methanopyrus, Methanocaldococcus) in cooler surface strata, no genes were detected below 10 cm (>60 °C). While mcrAbased and 16S rRNA gene-based community compositions are generally congruent, the deeply branching mcrA cannot be assigned to specific 16S rRNA gene lineages. Our study indicates that even among well-studied metabolic groups and in previously characterized model environments, major evolutionary branches are overlooked. Detecting these groups by improved molecular biological methods is a crucial first step toward understanding their roles in nature.

  18. Wronskian solutions of the T-, Q- and Y-systems related to infinite dimensional unitarizable modules of the general linear superalgebra gl (M | N)

    NASA Astrophysics Data System (ADS)

    Tsuboi, Zengo

    2013-05-01

    In [1] (Z. Tsuboi, Nucl. Phys. B 826 (2010) 399, arxiv:arXiv:0906.2039), we proposed Wronskian-like solutions of the T-system for [ M , N ]-hook of the general linear superalgebra gl (M | N). We have generalized these Wronskian-like solutions to the ones for the general T-hook, which is a union of [M1 ,N1 ]-hook and [M2 ,N2 ]-hook (M =M1 +M2, N =N1 +N2). These solutions are related to Weyl-type supercharacter formulas of infinite dimensional unitarizable modules of gl (M | N). Our solutions also include a Wronskian-like solution discussed in [2] (N. Gromov, V. Kazakov, S. Leurent, Z. Tsuboi, JHEP 1101 (2011) 155, arxiv:arXiv:1010.2720) in relation to the AdS5 /CFT4 spectral problem.

  19. General analysis of group velocity effects in collinear optical parametric amplifiers and generators.

    PubMed

    Arisholm, Gunnar

    2007-05-14

    Group velocity mismatch (GVM) is a major concern in the design of optical parametric amplifiers (OPAs) and generators (OPGs) for pulses shorter than a few picoseconds. By simplifying the coupled propagation equations and exploiting their scaling properties, the number of free parameters for a collinear OPA is reduced to a level where the parameter space can be studied systematically by simulations. The resulting set of figures show the combinations of material parameters and pulse lengths for which high performance can be achieved, and they can serve as a basis for a design.

  20. General guidelines for medically screening mixed population groups potentially exposed to nerve or vesicant agents

    SciTech Connect

    Watson, A.P.; Munro, N.B. ); Sidell, F.R. ); Leffingwell, S.S. . Center for Environmental Health and Injury Control)

    1992-01-01

    A number of state and local planners have requested guidance on screening protocols and have expressed interest in sampling body fluids from exposed or potentially exposed individuals as a means of estimating agent dose. These guidelines have been developed to provide a clear statement that could be used by state and local emergency response personnel in the event of a nerve or vesicant agent incident resulting in off-post contamination; maximum protection from harm is the goal. The assumption is that any population group so exposed would be heterogeneous for age, gender, reproductive status, and state of health.

  1. Learning to fit in: an exploratory study of general perceived self efficacy in selected refugee groups.

    PubMed

    Sulaiman-Hill, Cheryl M R; Thompson, Sandra C

    2013-02-01

    As self efficacy beliefs help determine an individual's response to challenging situations, we explored the impact of the refugee experience on efficacy beliefs and their contribution to resettlement. General self efficacy (GSE) was assessed in 186 resettled Afghan and Kurdish refugees against a range of personal and temporal variables. Although no differences in GSE in relation to temporal factors were noted, significant relationships between self efficacy, lower psychological distress and higher subjective well being were evident. The findings suggest that GSE, because of its positive association with mental health and well being, is a variable worthy of further examination in refugees. In addition to ensuring a supportive environment for learning English, proactive employment strategies should be encouraged. Further research examining the use of successful refugee role models to promote self efficacy, enhance motivation for learning and ensure newly arrived refugees view resettlement as a challenge, rather than a threat, is recommended.

  2. Digital communication between clinician and patient and the impact on marginalised groups: a realist review in general practice

    PubMed Central

    Huxley, Caroline J; Atherton, Helen; Watkins, Jocelyn Anstey; Griffiths, Frances

    2015-01-01

    Background Increasingly, the NHS is embracing the use of digital communication technology for communication between clinicians and patients. Policymakers deem digital clinical communication as presenting a solution to the capacity issues currently faced by general practice. There is some concern that these technologies may exacerbate existing inequalities in accessing health care. It is not known what impact they may have on groups who are already marginalised in their ability to access general practice. Aim To assess the potential impact of the availability of digital clinician–patient communication on marginalised groups’ access to general practice in the UK. Design and setting Realist review in general practice. Method A four-step realist review process was used: to define the scope of the review; to search for and scrutinise evidence; to extract and synthesise evidence; and to develop a narrative, including hypotheses. Results Digital communication has the potential to overcome the following barriers for marginalised groups: practical access issues, previous negative experiences with healthcare service/staff, and stigmatising reactions from staff and other patients. It may reduce patient-related barriers by offering anonymity and offers advantages to patients who require an interpreter. It does not impact on inability to communicate with healthcare professionals or on a lack of candidacy. It is likely to work best in the context of a pre-existing clinician–patient relationship. Conclusion Digital communication technology offers increased opportunities for marginalised groups to access health care. However, it cannot remove all barriers to care for these groups. It is likely that they will remain disadvantaged relative to other population groups after their introduction. PMID:26622034

  3. Solutions for Determining the Significance Region Using the Johnson-Neyman Type Procedure in Generalized Linear (Mixed) Models

    ERIC Educational Resources Information Center

    Lazar, Ann A.; Zerbe, Gary O.

    2011-01-01

    Researchers often compare the relationship between an outcome and covariate for two or more groups by evaluating whether the fitted regression curves differ significantly. When they do, researchers need to determine the "significance region," or the values of the covariate where the curves significantly differ. In analysis of covariance (ANCOVA),…

  4. Group cognitive-behavioral therapy for generalized anxiety disorder: treatment outcome and long-term follow-up.

    PubMed

    Dugas, Michel J; Ladouceur, Robert; Léger, Eliane; Freeston, Mark H; Langlois, Frédéric; Provencher, Martin D; Boisvert, Jean-Marie

    2003-08-01

    A recently developed cognitive-behavioral treatment for generalized anxiety disorder (GAD) targets intolerance of uncertainty by the reevaluation of positive beliefs about worry, problem-solving training, and cognitive exposure. As previous studies have established the treatment's efficacy when delivered individually, the present study tests the treatment in a group format as a way to enhance its cost-benefit ratio. A total of 52 GAD patients received 14 sessions of cognitive-behavioral therapy in small groups of 4 to 6 participants. A wait-list control design was used, and standardized clinician ratings and self-report questionnaires assessed GAD symptoms, intolerance of uncertainty, anxiety, depression, and social adjustment. Results show that the treatment group, relative to the wait-list group, had greater posttest improvement on all dependent variables and that treated participants made further gains over the 2-year follow-up phase of the study.

  5. SUMMARY OF GENERAL WORKING GROUP A+B+D: CODES BENCHMARKING.

    SciTech Connect

    WEI, J.; SHAPOSHNIKOVA, E.; ZIMMERMANN, F.; HOFMANN, I.

    2006-05-29

    Computer simulation is an indispensable tool in assisting the design, construction, and operation of accelerators. In particular, computer simulation complements analytical theories and experimental observations in understanding beam dynamics in accelerators. The ultimate function of computer simulation is to study mechanisms that limit the performance of frontier accelerators. There are four goals for the benchmarking of computer simulation codes, namely debugging, validation, comparison and verification: (1) Debugging--codes should calculate what they are supposed to calculate; (2) Validation--results generated by the codes should agree with established analytical results for specific cases; (3) Comparison--results from two sets of codes should agree with each other if the models used are the same; and (4) Verification--results from the codes should agree with experimental measurements. This is the summary of the joint session among working groups A, B, and D of the HI32006 Workshop on computer codes benchmarking.

  6. DNA SEQUENCING RESEARCH GROUP (DSRG) 2003—A GENERAL SURVEY OF CORE DNA SEQUENCING FACILITIES

    PubMed Central

    Wiebe, Glenis J.; Pershad, Rashmi; Escobar, Helaman; Hawes, John W.; Hunter, Timothy; Jackson-Machelski, Emily; Knudtson, Kevin L.; Robertson, Margaret; Thannhauser, Theodore W.

    2003-01-01

    DNA sequencing core facilities serve as centralized resources within both academic and commercial institutions, providing expertise in the area of DNA analysis. The composition and configuration of these facilities continue to evolve in response to new developments in instrumentation and methodology. The goal of the 2003 DNA Sequencing Research Group (DSRG) survey was to identify recent changes in staffing, funding, instrumentation, services, and customer relations. Responses to 58 survey questions from 30 participants are presented to offer a look at the current typical DNA core sequencing facility. The results from this study will serve as a resource for institutions to benchmark their shared core laboratories, and to give facility directors an opportunity to compare and contrast their respective services and experiences.

  7. Direct Linearization and Adjoint Approaches to Evaluation of Atmospheric Weighting Functions and Surface Partial Derivatives: General Principles, Synergy and Areas of Application

    NASA Technical Reports Server (NTRS)

    Ustino, Eugene A.

    2006-01-01

    This slide presentation reviews the observable radiances as functions of atmospheric parameters and of surface parameters; the mathematics of atmospheric weighting functions (WFs) and surface partial derivatives (PDs) are presented; and the equation of the forward radiative transfer (RT) problem is presented. For non-scattering atmospheres this can be done analytically, and all WFs and PDs can be computed analytically using the direct linearization approach. For scattering atmospheres, in general case, the solution of the forward RT problem can be obtained only numerically, but we need only two numerical solutions: one of the forward RT problem and one of the adjoint RT problem to compute all WFs and PDs we can think of. In this presentation we discuss applications of both the linearization and adjoint approaches

  8. Intensive care discharge summaries for general practice staff: a focus group study

    PubMed Central

    Bench, Suzanne; Cornish, Jocelyn; Xyrichis, Andreas

    2016-01-01

    Background Understanding how patients and relatives can be supported after hospital discharge is a UK research priority. Intensive Care Unit (ICU) discharge summaries are a simple way of providing GPs with the information they require to coordinate ongoing care, but little evidence is available to guide best practice. Aim This study aimed at better understanding the information needs of GP staff (GPs and practice nurses) supporting former patients of ICUs and their families following discharge from hospital, and identifying the barriers/facilitators associated with ICU–primary care information transfer. Design and setting This was a qualitative exploratory study of practices and participants throughout the UK. Method Audiotaped focus group discussions, complemented by small-group/individual interviews, were conducted with 15 former patients of ICUs, four relatives, and 20 GP staff between June and September 2015. Demographic data were captured by questionnaire and qualitative data were thematically analysed. Results Findings suggest variability in discharge information experiences and blurred lines of responsibility between hospital and GP staff, and patients/relatives. Continuity of care was affected by delayed or poor communication from the hospital; GPs’ limited contact with patients from critical care; and a lack of knowledge of the effects of critical illness or resources available to ameliorate these difficulties. Time pressures and information technology were, respectively, the most commonly mentioned barrier and facilitator. Conclusion Effective rehabilitation after a critical illness requires a coordinated and comprehensive approach, incorporating the provision of well-completed, timely, and relevant ICU–primary care discharge information. Health professionals need an improved understanding of critical illness, and patients and families must be included in all aspects of the information-sharing process. PMID:27872086

  9. Polynomial approximation of functions of matrices and its application to the solution of a general system of linear equations

    NASA Technical Reports Server (NTRS)

    Tal-Ezer, Hillel

    1987-01-01

    During the process of solving a mathematical model numerically, there is often a need to operate on a vector v by an operator which can be expressed as f(A) while A is NxN matrix (ex: exp(A), sin(A), A sup -1). Except for very simple matrices, it is impractical to construct the matrix f(A) explicitly. Usually an approximation to it is used. In the present research, an algorithm is developed which uses a polynomial approximation to f(A). It is reduced to a problem of approximating f(z) by a polynomial in z while z belongs to the domain D in the complex plane which includes all the eigenvalues of A. This problem of approximation is approached by interpolating the function f(z) in a certain set of points which is known to have some maximal properties. The approximation thus achieved is almost best. Implementing the algorithm to some practical problem is described. Since a solution to a linear system Ax = b is x= A sup -1 b, an iterative solution to it can be regarded as a polynomial approximation to f(A) = A sup -1. Implementing the algorithm in this case is also described.

  10. Outcomes of hepatitis C screening programs targeted at risk groups hidden in the general population: a systematic review

    PubMed Central

    2014-01-01

    Background Effective screening programs are urgently needed to provide undiagnosed hepatitis C virus (HCV)-infected individuals with therapy. This systematic review of characteristics and outcomes of screening programs for HCV focuses on strategies to identify HCV risk groups hidden in the general population. Methods We conducted a comprehensive search of MEDLINE and EMBASE databases for articles published between 1991–2010, including studies that screened the general population using either a newly developed (nonintegrated) screening program or one integrated in existing health care facilities. Look-back studies, prevalence studies, and programs targeting high-risk groups in care (e.g., current drug users) were excluded. Results After reviewing 7052 studies, we identified 67 screening programs: 24 nonintegrated; 41 programs integrated in a variety of health care facilities (e.g., general practitioner); and 2 programs with both integrated and nonintegrated strategies. Together, these programs identified approximately 25,700 HCV-infected individuals. In general, higher HCV prevalence was found in programs in countries with intermediate to high HCV prevalence, in psychiatric clinics, and in programs that used a prescreening selection based on HCV risk factors. Only 6 programs used a comparison group for evaluation purposes, and 1 program used theory about effective promotion for screening. Comparison of the programs and their effectiveness was hampered by lack of reported data on program characteristics, clinical follow-up, and type of diagnostic test. Conclusions A prescreening selection based on risk factors can increase the efficiency of screening in low-prevalence populations, and we need programs with comparison groups to evaluate effectiveness. Also, program characteristics such as type of diagnostic test, screening uptake, and clinical outcomes should be reported systematically. PMID:24450797

  11. Screening for celiac disease in the general population and in high-risk groups

    PubMed Central

    Card, Timothy R; Kaukinen, Katri; Bai, Julio; Zingone, Fabiana; Sanders, David S; Murray, Joseph A

    2015-01-01

    Background Celiac disease (CD) occurs in approximately 1% of the Western population. It is a lifelong disorder that is associated with impaired quality of life (QOL) and an excessive risk of comorbidity and death. Objectives To review the literature on screening for CD in relation to the current World Health Organization (WHO) criteria for mass screening. Methods We performed a PubMed search to identify indexed papers on CD screening with a publication date from 1900 until 1 June 2014. When we deemed an abstract relevant, we read the corresponding paper in detail. Results CD fulfills several WHO criteria for mass screening (high prevalence, available treatment and difficult clinical detection), but it has not yet been established that treatment of asymptomatic CD may reduce the excessive risk of severe complications, leading to higher QOL nor that it is cost-effective. Conclusions Current evidence is not sufficient to support mass screening for CD, but active case-finding may be appropriate, as we recognize that most patients with CD will still be missed by this strategy. Although proof of benefit is still lacking, screening for CD may be appropriate in high-risk groups. PMID:25922671

  12. An a-posteriori error estimator for linear elastic fracture mechanics using the stable generalized/extended finite element method

    NASA Astrophysics Data System (ADS)

    Lins, R. M.; Ferreira, M. D. C.; Proença, S. P. B.; Duarte, C. A.

    2015-12-01

    In this study, a recovery-based a-posteriori error estimator originally proposed for the Corrected XFEM is investigated in the framework of the stable generalized FEM (SGFEM). Both Heaviside and branch functions are adopted to enrich the approximations in the SGFEM. Some necessary adjustments to adapt the expressions defining the enhanced stresses in the original error estimator are discussed in the SGFEM framework. Relevant aspects such as effectivity indexes, error distribution, convergence rates and accuracy of the recovered stresses are used in order to highlight the main findings and the effectiveness of the error estimator. Two benchmark problems of the 2-D fracture mechanics are selected to assess the robustness of the error estimator hereby investigated. The main findings of this investigation are: the SGFEM shows higher accuracy than G/XFEM and a reduced sensitivity to blending element issues. The error estimator can accurately capture these features of both methods.

  13. Quantum, classical, and hybrid QM/MM calculations in solution: General implementation of the ddCOSMO linear scaling strategy

    SciTech Connect

    Lipparini, Filippo; Scalmani, Giovanni; Frisch, Michael J.; Lagardère, Louis; Stamm, Benjamin; Cancès, Eric; Maday, Yvon; Piquemal, Jean-Philip; Mennucci, Benedetta

    2014-11-14

    We present the general theory and implementation of the Conductor-like Screening Model according to the recently developed ddCOSMO paradigm. The various quantities needed to apply ddCOSMO at different levels of theory, including quantum mechanical descriptions, are discussed in detail, with a particular focus on how to compute the integrals needed to evaluate the ddCOSMO solvation energy and its derivatives. The overall computational cost of a ddCOSMO computation is then analyzed and decomposed in the various steps: the different relative weights of such contributions are then discussed for both ddCOSMO and the fastest available alternative discretization to the COSMO equations. Finally, the scaling of the cost of the various steps with respect to the size of the solute is analyzed and discussed, showing how ddCOSMO opens significantly new possibilities when cheap or hybrid molecular mechanics/quantum mechanics methods are used to describe the solute.

  14. Extraintestinal salmonellosis in a general hospital (1991 to 1996): relationships between Salmonella genomic groups and clinical presentations.

    PubMed

    Rodríguez, M; de Diego, I; Mendoza, M C

    1998-11-01

    Episodes of extraintestinal salmonellosis treated at a general hospital (1,522 beds) over a 6-year period (1991 to 1996) were characterized by the analysis of phenotypic and genotypic traits of Salmonella organisms and clinical data from medical reports. Extraintestinal salmonellosis accounted for 8% of all salmonellosis episodes. Fifty-two medical reports, dealing with 6 cases of typhoid fever, 32 cases of bacteremia, and 14 focal infections, were reviewed. All cases of typhoid fever except 1, 7 cases of bacteremia, and 5 focal infections were not related to any underlying disease or predisposing factors, while 25 cases of bacteremia and 9 focal infections were associated with some of these risk factors. All typhoid isolates and 65.4% of the nontyphoid isolates were susceptible to antimicrobials. Fifty-one nontyphoid strains were analyzed and assigned to 21 genomic groups, which were defined by serotype, combined ribotype, and combined randomly amplified polymorphic DNA type (each genomic group could include organisms differing in some phenotypic traits). The relationships between genomic groups and clinical presentations were traced. Organisms causing 22 episodes (17 episodes of bacteremia, 2 of pneumonia, 1 of peritonitis, 1 of pyelonephritis, and 1 of cystitis) belonged to a prevalent Salmonella enterica serotype Enteritidis genomic group, which included organisms assigned to four phage types, five biotypes, and four resistance patterns, causing infections in patients with and without risk factors. Seven other genomic groups, 4 Enteritidis groups (associated with both bacteremia and focal infections), 2 Typhimurium groups (one associated with bacteremia and the other with focal infections) and 1 Brandenburg group (associated with bacteremia) included two or more strains, and the remaining 13 genomic groups consisted of only one strain each.

  15. A generalized partially linear mean-covariance regression model for longitudinal proportional data, with applications to the analysis of quality of life data from cancer clinical trials.

    PubMed

    Zheng, Xueying; Qin, Guoyou; Tu, Dongsheng

    2017-02-19

    Motivated by the analysis of quality of life data from a clinical trial on early breast cancer, we propose in this paper a generalized partially linear mean-covariance regression model for longitudinal proportional data, which are bounded in a closed interval. Cholesky decomposition of the covariance matrix for within-subject responses and generalized estimation equations are used to estimate unknown parameters and the nonlinear function in the model. Simulation studies are performed to evaluate the performance of the proposed estimation procedures. Our new model is also applied to analyze the data from the cancer clinical trial that motivated this research. In comparison with available models in the literature, the proposed model does not require specific parametric assumptions on the density function of the longitudinal responses and the probability function of the boundary values and can capture dynamic changes of time or other interested variables on both mean and covariance of the correlated proportional responses. Copyright © 2017 John Wiley & Sons, Ltd.

  16. Well-conditioning global-local analysis using stable generalized/extended finite element method for linear elastic fracture mechanics

    NASA Astrophysics Data System (ADS)

    Malekan, Mohammad; Barros, Felicio Bruzzi

    2016-11-01

    Using the locally-enriched strategy to enrich a small/local part of the problem by generalized/extended finite element method (G/XFEM) leads to non-optimal convergence rate and ill-conditioning system of equations due to presence of blending elements. The local enrichment can be chosen from polynomial, singular, branch or numerical types. The so-called stable version of G/XFEM method provides a well-conditioning approach when only singular functions are used in the blending elements. This paper combines numeric enrichment functions obtained from global-local G/XFEM method with the polynomial enrichment along with a well-conditioning approach, stable G/XFEM, in order to show the robustness and effectiveness of the approach. In global-local G/XFEM, the enrichment functions are constructed numerically from the solution of a local problem. Furthermore, several enrichment strategies are adopted along with the global-local enrichment. The results obtained with these enrichments strategies are discussed in detail, considering convergence rate in strain energy, growth rate of condition number, and computational processing. Numerical experiments show that using geometrical enrichment along with stable G/XFEM for global-local strategy improves the convergence rate and the conditioning of the problem. In addition, results shows that using polynomial enrichment for global problem simultaneously with global-local enrichments lead to ill-conditioned system matrices and bad convergence rate.

  17. Domain-general mechanisms: what they are, how they evolved, and how they interact with modular, domain-specific mechanisms to enable cohesive human groups.

    PubMed

    MacDonald, Kevin

    2014-08-01

    Domain-general mechanisms are evolutionarily ancient, resulting from the evolution of affective cues signaling the attainment of evolutionary goals. Explicit processing is a particularly important set of domain-general mechanisms for constructing human groups - enabling ideologies specifying future goal states and rationalizing group aims, enabling knowledge of others' reputations essential to cooperation, understanding the rights and obligations of group membership, monitoring group members, and providing appropriate punishments to those who deviate from group aims.

  18. Generalized linear dynamics of a plant-parasitic nematode population and the economic evaluation of crop rotations.

    PubMed

    Van Den Berg, W; Rossing, W A H

    2005-03-01

    In 1-year experiments, the final population density of nematodes is usually modeled as a function of initial density. Often, estimation of the parameters is precarious because nematode measurements, although laborious and expensive, are imprecise and the range in initial densities may be small. The estimation procedure can be improved by using orthogonal regression with a parameter for initial density on each experimental unit. In multi-year experiments parameters of a dynamic model can be estimated with optimization techniques like simulated annealing or Bayesian methods such as Markov chain Monte Carlo (MCMC). With these algorithms information from different experiments can be combined. In multi-year dynamic models, the stability of the steady states is an important issue. With chaotic dynamics, prediction of densities and associated economic loss will be possible only on a short timescale. In this study, a generic model was developed that describes population dynamics in crop rotations. Mathematical analysis showed stable steady states do exist for this dynamic model. Using the Metropolis algorithm, the model was fitted to data from a multi-year experiment on Pratylenchus penetrans dynamics with treatments that varied between years. For three crops, parameters for a yield loss assessment model were available and gross margin of the six possible rotations comprising these three crops and a fallow year were compared at the steady state of nematode density. Sensitivity of mean gross margin to changes in the parameter estimates was investigated. We discuss the general applicability of the dynamic rotation model and the opportunities arising from combination of the model with Bayesian calibration techniques for more efficient utilization and collection of data relevant for economic evaluation of crop rotations.

  19. Use and Uptake of eHealth in General Practice: A Cross-Sectional Survey and Focus Group Study Among Health Care Users and General Practitioners

    PubMed Central

    Krijgsman, Johan W; Brabers, Anne E; Jong, Judith D De; Friele, Roland D

    2016-01-01

    Background Policy makers promote the use of eHealth to widen access to health care services and to improve the quality and safety of care. Nevertheless, the enthusiasm among policy makers for eHealth does not match its uptake and use. eHealth is defined in this study as “health services delivered or enhanced through the Internet and related information and communication technologies.” Objective The objective of this study was to investigate (1) the current use of eHealth in the Netherlands by general practitioners (GPs) and health care users, (2) the future plans of GPs to provide eHealth and the willingness of health care users to use eHealth services, and (3) the perceived positive effects and barriers from the perspective of GPs and health care users. Methods A cross-sectional survey of a sample of Dutch GPs and members of the Dutch Health Care Consumer Panel was conducted in April 2014. A pre-structured questionnaire was completed by 171 GPs (12% response) and by 754 health care users (50% response). In addition, two focus groups were conducted in June 2014: one group with GPs (8 participants) and one with health care users (10 participants). Results Three-quarters of Dutch GPs that responded to the questionnaire (67.3%, 115/171) offered patients the possibility of requesting a prescription via the Internet, and half of them offered patients the possibility of asking a question via the Internet (49.1%, 84/171). In general, they did intend to provide future eHealth services. Nonetheless, many of the GPs perceived barriers, especially concerning its innovation (eg, insufficient reliable, secure systems) and the sociopolitical context (eg, lack of financial compensation for the time spent on implementation). By contrast, health care users were generally not aware of existing eHealth services offered by their GPs. Nevertheless, half of them were willing to use eHealth services when offered by their GP. In general, health care users have positive attitudes

  20. Algorithmic framework for group analysis of differential equations and its application to generalized Zakharov-Kuznetsov equations

    NASA Astrophysics Data System (ADS)

    Huang, Ding-jiang; Ivanova, Nataliya M.

    2016-02-01

    In this paper, we explain in more details the modern treatment of the problem of group classification of (systems of) partial differential equations (PDEs) from the algorithmic point of view. More precisely, we revise the classical Lie algorithm of construction of symmetries of differential equations, describe the group classification algorithm and discuss the process of reduction of (systems of) PDEs to (systems of) equations with smaller number of independent variables in order to construct invariant solutions. The group classification algorithm and reduction process are illustrated by the example of the generalized Zakharov-Kuznetsov (GZK) equations of form ut +(F (u)) xxx +(G (u)) xyy +(H (u)) x = 0. As a result, a complete group classification of the GZK equations is performed and a number of new interesting nonlinear invariant models which have non-trivial invariance algebras are obtained. Lie symmetry reductions and exact solutions for two important invariant models, i.e., the classical and modified Zakharov-Kuznetsov equations, are constructed. The algorithmic framework for group analysis of differential equations presented in this paper can also be applied to other nonlinear PDEs.

  1. The Effectiveness of Mindfulness-Based Cognitive Group Therapy on Marital Satisfaction and General Health in Woman With Infertility

    PubMed Central

    Shargh, Najmeh Abedi; Bakhshani, Nour Mohammad; Mohebbi, Mohammad Davoud; Mahmudian, Khadije; Ahovan, Masood; Mokhtari, Mojgan; Gangali, Alireza

    2016-01-01

    Infertility affects around 80 million people around the world and it has been estimated that psychological problems in infertile couples is within the range of 25-60%. The purpose of this study was to determine the effectiveness of Mindfulness-based cognitive group therapy on consciousness regarding marital satisfaction and general health in woman with infertility. Recent work is a clinical trial with a pre/posttest plan for control group. Covering 60 women who were selected by in access method and arranged randomly in interference (30) and control (30) groups. Before and after implementation of independent variable, all subjects were measured in both groups using Enrich questionnaire and marital satisfaction questionnaire. Results of covariance analysis of posttest, after controlling the scores of pretest illustrated the meaningful difference of marital satisfaction and mental health scores in interference and control groups after treatment and the fact that MBCT treatment in infertile women revealed that this method has an appropriate contribution to improvement of marital satisfaction and mental health. Necessary trainings for infertile people through consultation services can improve their mental health and marital satisfaction and significantly help reducing infertile couples’ problems. PMID:26493418

  2. The diagnostic role of gut feelings in general practice A focus group study of the concept and its determinants

    PubMed Central

    Stolper, Erik; van Bokhoven, Marloes; Houben, Paul; Van Royen, Paul; van de Wiel, Margje; van der Weijden, Trudy; Jan Dinant, Geert

    2009-01-01

    Background General practitioners sometimes base clinical decisions on gut feelings alone, even though there is little evidence of their diagnostic and prognostic value in daily practice. Research into these aspects and the use of the concept in medical education require a practical and valid description of gut feelings. The goal of our study was therefore to describe the concept of gut feelings in general practice and to identify their main determinants Methods Qualitative research including 4 focus group discussions. A heterogeneous sample of 28 GPs. Text analysis of the focus group discussions, using a grounded theory approach. Results Gut feelings are familiar to most GPs in the Netherlands and play a substantial role in their everyday routine. The participants distinguished two types of gut feelings, a sense of reassurance and a sense of alarm. In the former case, a GP is sure about prognosis and therapy, although they may not always have a clear diagnosis in mind. A sense of alarm means that a GP has the feeling that something is wrong even though objective arguments are lacking. GPs in the focus groups experienced gut feelings as a compass in situations of uncertainty and the majority of GPs trusted this guide. We identified the main determinants of gut feelings: fitting, alerting and interfering factors, sensation, contextual knowledge, medical education, experience and personality. Conclusion The role of gut feelings in general practice has become much clearer, but we need more research into the contributions of individual determinants and into the test properties of gut feelings to make the concept suitable for medical education. PMID:19226455

  3. Race and Ethnic Group Differences in Comorbid Major Depressive Disorder, Generalized Anxiety Disorder, and Chronic Medical Conditions.

    PubMed

    Watkins, Daphne C; Assari, Shervin; Johnson-Lawrence, Vicki

    2015-09-01

    This study tested whether race and ethnic group differences exist for lifetime major depressive disorder and/or general anxiety disorder with one or more chronic medical conditions. Data from the National Survey of American Life, which included 3570 African American, 1438 Caribbean Black, and 891 non-Hispanic White adults were analyzed. Outcomes included at least one and multiple chronic medical conditions, from a list of 14 medical conditions (e.g., arthritis, cancer, diabetes, kidney disease, stroke, heart disease, etc.). Logistic regressions were fitted to data to determine how the association between major depressive disorder, general anxiety disorder, and one or more chronic medical conditions vary across race and ethnicity. Lifetime major depressive disorder (but not lifetime general anxiety disorder) was associated with at least one chronic medical condition among African Americans and Caribbean Blacks, but not non-Hispanic Whites. Lifetime major depressive disorder was similarly associated with multiple chronic medical conditions among African Americans, Caribbean Blacks, and non-Hispanic Whites. For Caribbean Blacks, stronger associations were found between major depressive disorder and general anxiety disorder with one or more chronic medical conditions compared to African Americans and non-Hispanic Whites. Findings suggest that race and ethnicity may shape the links between comorbid psychiatric disorders and chronic medical conditions. Mental health screening of individuals with chronic medical conditions in primary health-care settings may benefit from tailoring based on race and ethnicity. More research is needed to understand why associations between physical and mental health vary among race and ethnic groups.

  4. Efficient tree tensor network states (TTNS) for quantum chemistry: generalizations of the density matrix renormalization group algorithm.

    PubMed

    Nakatani, Naoki; Chan, Garnet Kin-Lic

    2013-04-07

    We investigate tree tensor network states for quantum chemistry. Tree tensor network states represent one of the simplest generalizations of matrix product states and the density matrix renormalization group. While matrix product states encode a one-dimensional entanglement structure, tree tensor network states encode a tree entanglement structure, allowing for a more flexible description of general molecules. We describe an optimal tree tensor network state algorithm for quantum chemistry. We introduce the concept of half-renormalization which greatly improves the efficiency of the calculations. Using our efficient formulation we demonstrate the strengths and weaknesses of tree tensor network states versus matrix product states. We carry out benchmark calculations both on tree systems (hydrogen trees and π-conjugated dendrimers) as well as non-tree molecules (hydrogen chains, nitrogen dimer, and chromium dimer). In general, tree tensor network states require much fewer renormalized states to achieve the same accuracy as matrix product states. In non-tree molecules, whether this translates into a computational savings is system dependent, due to the higher prefactor and computational scaling associated with tree algorithms. In tree like molecules, tree network states are easily superior to matrix product states. As an illustration, our largest dendrimer calculation with tree tensor network states correlates 110 electrons in 110 active orbitals.

  5. Linear perturbation renormalization group for the two-dimensional Ising model with nearest- and next-nearest-neighbor interactions in a field

    NASA Astrophysics Data System (ADS)

    Sznajd, J.

    2016-12-01

    The linear perturbation renormalization group (LPRG) is used to study the phase transition of the weakly coupled Ising chains with intrachain (J ) and interchain nearest-neighbor (J1) and next-nearest-neighbor (J2) interactions forming the triangular and rectangular lattices in a field. The phase diagrams with the frustration point at J2=-J1/2 for a rectangular lattice and J2=-J1 for a triangular lattice have been found. The LPRG calculations support the idea that the phase transition is always continuous except for the frustration point and is accompanied by a divergence of the specific heat. For the antiferromagnetic chains, the external field does not change substantially the shape of the phase diagram. The critical temperature is suppressed to zero according to the power law when approaching the frustration point with an exponent dependent on the value of the field.

  6. Linear perturbation renormalization group for the two-dimensional Ising model with nearest- and next-nearest-neighbor interactions in a field.

    PubMed

    Sznajd, J

    2016-12-01

    The linear perturbation renormalization group (LPRG) is used to study the phase transition of the weakly coupled Ising chains with intrachain (J) and interchain nearest-neighbor (J_{1}) and next-nearest-neighbor (J_{2}) interactions forming the triangular and rectangular lattices in a field. The phase diagrams with the frustration point at J_{2}=-J_{1}/2 for a rectangular lattice and J_{2}=-J_{1} for a triangular lattice have been found. The LPRG calculations support the idea that the phase transition is always continuous except for the frustration point and is accompanied by a divergence of the specific heat. For the antiferromagnetic chains, the external field does not change substantially the shape of the phase diagram. The critical temperature is suppressed to zero according to the power law when approaching the frustration point with an exponent dependent on the value of the field.

  7. Decomposition of small-footprint full waveform LiDAR data based on generalized Gaussian model and grouping LM optimization

    NASA Astrophysics Data System (ADS)

    Ma, Hongchao; Zhou, Weiwei; Zhang, Liang; Wang, Suyuan

    2017-04-01

    Full waveform airborne Light Detection And Ranging(LiDAR) data contains abundant information which may overcome some deficiencies of discrete LiDAR point cloud data provided by conventional LiDAR systems. Processing full waveform data to extract more information than coordinate values alone is of great significance for potential applications. The Levenberg–Marquardt (LM) algorithm is a traditional method used to estimate parameters of a Gaussian model when Gaussian decomposition of full waveform LiDAR data is performed. This paper employs the generalized Gaussian mixture function to fit a waveform, and proposes using the grouping LM algorithm to optimize the parameters of the function. It is shown that the grouping LM algorithm overcomes the common drawbacks which arise from the conventional LM for parameter optimization, such as the final results being influenced by the initial parameters, possible algorithm interruption caused by non-numerical elements that occurred in the Jacobian matrix, etc. The precision of the point cloud generated by the grouping LM is evaluated by comparing it with those provided by the LiDAR system and those generated by the conventional LM. Results from both simulation and real data show that the proposed algorithm can generate a higher-quality point cloud, in terms of point density and precision, and can extract other information, such as echo location, pulse width, etc., more precisely as well.

  8. A pilot study of clonazepam versus psychodynamic group therapy plus clonazepam in the treatment of generalized social anxiety disorder

    PubMed Central

    Knijnik, Daniela Z.; Blanco, Carlos; Salum, Giovanni Abrahão; Moraes, Carolina U.; Mombach, Clarissa; Almeida, Ellen; Pereira, Marília; Strapasson, Atahualpa; Manfro, Gisele G.; Eizirik, Cláudio L.

    2015-01-01

    Background Both Psychodynamic Group Therapy (PGT) and clonazepam are used as treatment strategies in reducing symptoms of generalized social anxiety disorder (GSAD). However, many individuals remain symptomatic after treatment with PGT or clonazepam. Method Fifty-eight adult outpatients with a diagnosis of GSAD according to DSM-IV were randomized to 12 weeks PGT plus clonazepam or clonazepam. The Clinical Global Impression-Improvement (CGI-I) Scale was the primary efficacy measure. Secondary efficacy measures included the Liebowitz Social Anxiety Scale (LSAS) total score, the World Health Organization Instrument to Assess Quality of Life-Bref (WHOQOL-Bref) Scale and the Beck Depression Inventory (BDI). Results CGI-I data from 57 patients (intent-to-treat population) showed that patients who received PGT plus clonazepam presented significantly greater improvement than those who received clonazepam (p=0.033). There were no significant differences between the two groups in the secondary efficacy measures. Conclusion/Discussion Our study suggests that the combination of PGT with clonazepam may be a promising strategy for the treatment of GSAD, regarding gains in the global functioning. However the present study failed to detect more specific changes in social anxiety symptomatology between the two groups. PMID:18774274

  9. Euclidean Closed Linear Transformations of Complex Spacetime and generally of Complex Spaces of dimension four endowed with the Same or Different Metric

    NASA Astrophysics Data System (ADS)

    Vossos, Spyridon; Vossos, Elias

    2016-08-01

    closed LSTT is reduced, if one RIO has small velocity wrt another RIO. Thus, we have infinite number of closed LSTTs, each one with the corresponding SR theory. In case that we relate accelerated observers with variable metric of spacetime, we have the case of General Relativity (GR). For being that clear, we produce a generalized Schwarzschild metric, which is in accordance with any SR based on this closed complex LSTT and Einstein equations. The application of this kind of transformations to the SR and GR is obvious. But, the results may be applied to any linear space of dimension four endowed with steady or variable metric, whose elements (four- vectors) have spatial part (vector) with Euclidean metric.

  10. A general non-Abelian density matrix renormalization group algorithm with application to the C2 dimer

    NASA Astrophysics Data System (ADS)

    Sharma, Sandeep

    2015-01-01

    We extend our previous work [S. Sharma and G. K.-L. Chan, J. Chem. Phys. 136, 124121 (2012)], which described a spin-adapted (SU(2) symmetry) density matrix renormalization group algorithm, to additionally utilize general non-Abelian point group symmetries. A key strength of the present formulation is that the requisite tensor operators are not hard-coded for each symmetry group, but are instead generated on the fly using the appropriate Clebsch-Gordan coefficients. This allows our single implementation to easily enable (or disable) any non-Abelian point group symmetry (including SU(2) spin symmetry). We use our implementation to compute the ground state potential energy curve of the C2 dimer in the cc-pVQZ basis set (with a frozen-core), corresponding to a Hilbert space dimension of 1012 many-body states. While our calculated energy lies within the 0.3 mEh error bound of previous initiator full configuration interaction quantum Monte Carlo and correlation energy extrapolation by intrinsic scaling calculations, our estimated residual error is only 0.01 mEh, much more accurate than these previous estimates. Due to the additional efficiency afforded by the algorithm, the excitation energies (Te) of eight lowest lying excited states: a3Πu, b 3 Σg - , A1Πu, c 3 Σu + , B1Δg, B ' 1 Σg + , d3Πg, and C1Πg are calculated, which agree with experimentally derived values to better than 0.06 eV. In addition, we also compute the potential energy curves of twelve states: the three lowest levels for each of the irreducible representations 1 Σg + , 1 Σu + , 1 Σg - , and 1 Σu - , to an estimated accuracy of 0.1 mEh of the exact result in this basis.

  11. Generalized Vibrational Perturbation Theory for Rotovibrational Energies of Linear, Symmetric and Asymmetric Tops: Theory, Approximations, and Automated Approaches to Deal with Medium-to-Large Molecular Systems

    PubMed Central

    Piccardo, Matteo; Bloino, Julien; Barone, Vincenzo

    2015-01-01

    Models going beyond the rigid-rotor and the harmonic oscillator levels are mandatory for providing accurate theoretical predictions for several spectroscopic properties. Different strategies have been devised for this purpose. Among them, the treatment by perturbation theory of the molecular Hamiltonian after its expansion in power series of products of vibrational and rotational operators, also referred to as vibrational perturbation theory (VPT), is particularly appealing for its computational efficiency to treat medium-to-large systems. Moreover, generalized (GVPT) strategies combining the use of perturbative and variational formalisms can be adopted to further improve the accuracy of the results, with the first approach used for weakly coupled terms, and the second one to handle tightly coupled ones. In this context, the GVPT formulation for asymmetric, symmetric, and linear tops is revisited and fully generalized to both minima and first-order saddle points of the molecular potential energy surface. The computational strategies and approximations that can be adopted in dealing with GVPT computations are pointed out, with a particular attention devoted to the treatment of symmetry and degeneracies. A number of tests and applications are discussed, to show the possibilities of the developments, as regards both the variety of treatable systems and eligible methods. © 2015 Wiley Periodicals, Inc. PMID:26345131

  12. Generalized Vibrational Perturbation Theory for Rotovibrational Energies of Linear, Symmetric and Asymmetric Tops: Theory, Approximations, and Automated Approaches to Deal with Medium-to-Large Molecular Systems.

    PubMed

    Piccardo, Matteo; Bloino, Julien; Barone, Vincenzo

    2015-08-05

    Models going beyond the rigid-rotor and the harmonic oscillator levels are mandatory for providing accurate theoretical predictions for several spectroscopic properties. Different strategies have been devised for this purpose. Among them, the treatment by perturbation theory of the molecular Hamiltonian after its expansion in power series of products of vibrational and rotational operators, also referred to as vibrational perturbation theory (VPT), is particularly appealing for its computational efficiency to treat medium-to-large systems. Moreover, generalized (GVPT) strategies combining the use of perturbative and variational formalisms can be adopted to further improve the accuracy of the results, with the first approach used for weakly coupled terms, and the second one to handle tightly coupled ones. In this context, the GVPT formulation for asymmetric, symmetric, and linear tops is revisited and fully generalized to both minima and first-order saddle points of the molecular potential energy surface. The computational strategies and approximations that can be adopted in dealing with GVPT computations are pointed out, with a particular attention devoted to the treatment of symmetry and degeneracies. A number of tests and applications are discussed, to show the possibilities of the developments, as regards both the variety of treatable systems and eligible methods.

  13. Sources of stress for students in high school college preparatory and general education programs: group differences and associations with adjustment.

    PubMed

    Suldo, Shannon M; Shaunessy, Elizabeth; Thalji, Amanda; Michalowski, Jessica; Shaffer, Emily

    2009-01-01

    Navigating puberty while developing independent living skills may render adolescents particularly vulnerable to stress, which may ultimately contribute to mental health problems (Compas, Orosan, & Grant, 1993; Elgar, Arlett, & Groves, 2003). The academic transition to high school presents additional challenges as youth are required to interact with a new and larger peer group and manage greater academic expectations. For students enrolled in academically rigorous college preparatory programs, such as the International Baccalaureate (IB) program, the amount of stress perceived may be greater than typical (Suldo, Shaunessy, & Hardesty, 2008). This study investigated the environmental stressors and psychological adjustment of 162 students participating in the IB program and a comparison sample of 157 students in general education. Factor analysis indicated students experience 7 primary categories of stressors, which were examined in relation to students' adjustment specific to academic and psychological functioning. The primary source of stress experienced by IB students was related to academic requirements. In contrast, students in the general education program indicated higher levels of stressors associated with parent-child relations, academic struggles, conflict within family, and peer relations, as well as role transitions and societal problems. Comparisons of correlations between categories of stressors and students' adjustment by curriculum group reveal that students in the IB program reported more symptoms of psychopathology and reduced academic functioning as they experienced higher levels of stress, particularly stressors associated with academic requirements, transitions and societal problems, academic struggles, and extra-curricular activities. Applied implications stem from findings suggesting that students in college preparatory programs are more likely to (a) experience elevated stress related to academic demands as opposed to more typical adolescent

  14. On the characterization of dynamic supramolecular systems: a general mathematical association model for linear supramolecular copolymers and application on a complex two-component hydrogen-bonding system.

    PubMed

    Odille, Fabrice G J; Jónsson, Stefán; Stjernqvist, Susann; Rydén, Tobias; Wärnmark, Kenneth

    2007-01-01

    A general mathematical model for the characterization of the dynamic (kinetically labile) association of supramolecular assemblies in solution is presented. It is an extension of the equal K (EK) model by the stringent use of linear algebra to allow for the simultaneous presence of an unlimited number of different units in the resulting assemblies. It allows for the analysis of highly complex dynamic equilibrium systems in solution, including both supramolecular homo- and copolymers without the recourse to extensive approximations, in a field in which other analytical methods are difficult. The derived mathematical methodology makes it possible to analyze dynamic systems such as supramolecular copolymers regarding for instance the degree of polymerization, the distribution of a given monomer in different copolymers as well as its position in an aggregate. It is to date the only general means to characterize weak supramolecular systems. The model was fitted to NMR dilution titration data by using the program Matlab, and a detailed algorithm for the optimization of the different parameters has been developed. The methodology is applied to a case study, a hydrogen-bonded supramolecular system, salen 4+porphyrin 5. The system is formally a two-component system but in reality a three-component system. This results in a complex dynamic system in which all monomers are associated to each other by hydrogen bonding with different association constants, resulting in homo- and copolymers 4n5m as well as cyclic structures 6 and 7, in addition to free 4 and 5. The system was analyzed by extensive NMR dilution titrations at variable temperatures. All chemical shifts observed at different temperatures were used in the fitting to obtain the DeltaH degrees and DeltaS degrees values producing the best global fit. From the derived general mathematical expressions, system 4+5 could be characterized with respect to above-mentioned parameters.

  15. Evaluation of cavity occurrence in the Maynardville Limestone and the Copper Ridge Dolomite at the Y-12 Plant using logistic and general linear models

    SciTech Connect

    Shevenell, L.A.; Beauchamp, J.J.

    1994-11-01

    Several waste disposal sites are located on or adjacent to the karstic Maynardville Limestone (Cmn) and the Copper Ridge Dolomite (Ccr) at the Oak Ridge Y-12 Plant. These formations receive contaminants in groundwaters from nearby disposal sites, which can be transported quite rapidly due to the karst flow system. In order to evaluate transport processes through the karst aquifer, the solutional aspects of the formations must be characterized. As one component of this characterization effort, statistical analyses were conducted on the data related to cavities in order to determine if a suitable model could be identified that is capable of predicting the probability of cavity size or distribution in locations for which drilling data are not available. Existing data on the locations (East, North coordinates), depths (and elevations), and sizes of known conduits and other water zones were used in the analyses. Two different models were constructed in the attempt to predict the distribution of cavities in the vicinity of the Y-12 Plant: General Linear Models (GLM), and Logistic Regression Models (LOG). Each of the models attempted was very sensitive to the data set used. Models based on subsets of the full data set were found to do an inadequate job of predicting the behavior of the full data set. The fact that the Ccr and Cmn data sets differ significantly is not surprising considering the hydrogeology of the two formations differs. Flow in the Cmn is generally at elevations between 600 and 950 ft and is dominantly strike parallel through submerged, partially mud-filled cavities with sizes up to 40 ft, but more typically less than 5 ft. Recognized flow in the Ccr is generally above 950 ft elevation, with flow both parallel and perpendicular to geologic strike through conduits, which tend to be large than those on the Cnm, and are often not fully saturated at the shallower depths.

  16. General-Relativistic Three-Dimensional Multi-group Neutrino Radiation-Hydrodynamics Simulations of Core-Collapse Supernovae

    NASA Astrophysics Data System (ADS)

    Roberts, Luke F.; Ott, Christian D.; Haas, Roland; O'Connor, Evan P.; Diener, Peter; Schnetter, Erik

    2016-11-01

    We report on a set of long-term general-relativistic three-dimensional (3D) multi-group (energy-dependent) neutrino radiation-hydrodynamics simulations of core-collapse supernovae. We employ a full 3D two-moment scheme with the local M1 closure, three neutrino species, and 12 energy groups per species. With this, we follow the post-core-bounce evolution of the core of a nonrotating 27 - {M}⊙ progenitor in full unconstrained 3D and in octant symmetry for ≳380 ms. We find the development of an asymmetric runaway explosion in our unconstrained simulation. We test the resolution dependence of our results and, in agreement with previous work, find that low resolution artificially aids explosion and leads to an earlier runaway expansion of the shock. At low resolution, the octant and full 3D dynamics are qualitatively very similar, but at high resolution, only the full 3D simulation exhibits the onset of explosion.

  17. Cost justification of clinical pharmacy services on a general surgery team: focus on diagnosis-related group cases.

    PubMed

    Bertch, K E; Hatoum, H T; Willett, M S; Witte, K W

    1988-11-01

    We used a novel approach to cost-justify clinical pharmacy services on a general surgery team in nine diagnosis-related group cases. The clinical pharmacist monitored nine patients longitudinally on a general surgery team from admission to discharge and intervened in their therapeutic management. Each recommendation was analyzed for rationale, acceptance, perceived impact on quality and/or cost of patient care, whether self-initiated or solicited, and impact on patient outcome. Types of recommendations and outcomes were categorized by process and outcome measurement criteria. Total cost avoidance per patient was calculated using costs of drug therapy, laboratory tests, and length of stay. Accounting for cost of clinical pharmacy services, net cost avoidance per patient was calculated. The clinical pharmacist made 101 recommendations on nine patients. Physicians accepted 82 percent of the recommendations; 77 percent of the recommendations were self-initiated and 23 percent were solicited. Recommendations had a perceived impact on cost, quality, or both at 13, 31, and 56 percent, respectively. Most recommendations (79 percent) brought patient therapy to a level of conformance with current standards of practice as documented in the medical literature. Recommendations that potentially preserved a major organ function by preventing drug-induced toxicity or the exacerbation of existing problems constituted 16 percent of the total. None of the accepted recommendations adversely affected patient outcome and 23 percent directly resulted in a measurable positive outcome in patient care. A total of four hospital days was potentially saved for two cases. Based on objective outcome criteria, a 1.9-day increase in therapeutic control was documented per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Self-affinities for the amplitude and the wavelength of folds: A general renormalization-group argument

    NASA Astrophysics Data System (ADS)

    Kikuchi, K.; Nagahama, H.

    2013-12-01

    A method to analyze self-affinities is introduced and applied to the large scale fold geometries of Quaternary and Tertiary sediments in the inner belt of the Northeast Honshu Arc, Japan (Kikuchi et al. 2013). Based on this analysis, their geometries are self-affine and can be differently scaled in different directions. They recognize the self-affinities for the amplitude and the wavelength of folds and a crossover from local to global altitude (vertical) variation of the geometries of folds in the Northeast Honshu Arc. Moreover, they discuss self-affinity for the crustal deformation is related to the b-value in Gutenberg-Richter's law, the fractal dimension and the uniformity of the crustal fragmentation. Softening behaviour can lead to localisation of fold packets in layered materials and a progression to chaos with fractal geometries (Hunt and Wadee, 1991). Why do fractal geometries exist and what is the control on the fractal dimension that is responsible for temperature and strain-rate dependence?(Ord and Hobbs, 2011). Shimamoto (1974) examined the conditions of similarity for geometrically similar systems of inhomogeneous viscous Newtonian fluids under similar boundary conditions, making use of the method of dimensional analysis (Buckingham's Pi-theorem). Then, based on the completely similarity, he vividly derived a relationship between the wavelength of fold and initial thickness of folded layer. Buckingham's Pi-theorem is sufficient to the first problems of fold systems. But the complete similarity can not give us the self-affinities of folds. A general renormalization-group argument is proposed to the applicability of the incomplete self-similarity theory (Barenblatt, 1979). So in this paper, based on the general renormalization-group argument, we derive the self-affinities for the amplitude and the wavelength of folds. Keywords: Fold, Self-Affinities, Dimensional Analysis, Pi-theorem, Incomplete self-similarity R e f e r e n c e s Barenblatt, G.I. (1979

  19. Using generalized linear models to estimate selectivity from short-term recoveries of tagged red drum Sciaenops ocellatus: Effects of gear, fate, and regulation period

    USGS Publications Warehouse

    Bacheler, N.M.; Hightower, J.E.; Burdick, S.M.; Paramore, L.M.; Buckel, J.A.; Pollock, K.H.

    2010-01-01

    Estimating the selectivity patterns of various fishing gears is a critical component of fisheries stock assessment due to the difficulty in obtaining representative samples from most gears. We used short-term recoveries (n = 3587) of tagged red drum Sciaenops ocellatus to directly estimate age- and length-based selectivity patterns using generalized linear models. The most parsimonious models were selected using AIC, and standard deviations were estimated using simulations. Selectivity of red drum was dependent upon the regulation period in which the fish was caught, the gear used to catch the fish (i.e., hook-and-line, gill nets, pound nets), and the fate of the fish upon recovery (i.e., harvested or released); models including all first-order interactions between main effects outperformed models without interactions. Selectivity of harvested fish was generally dome-shaped and shifted toward larger, older fish in response to regulation changes. Selectivity of caught-and-released red drum was highest on the youngest and smallest fish in the early and middle regulation periods, but increased on larger, legal-sized fish in the late regulation period. These results suggest that catch-and-release mortality has consistently been high for small, young red drum, but has recently become more common in larger, older fish. This method of estimating selectivity from short-term tag recoveries is valuable because it is simpler than full tag-return models, and may be more robust because yearly fishing and natural mortality rates do not need to be modeled and estimated. ?? 2009 Elsevier B.V.

  20. Using generalized linear models to estimate selectivity from short-term recoveries of tagged red drum Sciaenops ocellatus: Effects of gear, fate, and regulation period

    USGS Publications Warehouse

    Burdick, Summer M.; Hightower, Joseph E.; Bacheler, Nathan M.; Paramore, Lee M.; Buckel, Jeffrey A.; Pollock, Kenneth H.

    2010-01-01

    Estimating the selectivity patterns of various fishing gears is a critical component of fisheries stock assessment due to the difficulty in obtaining representative samples from most gears. We used short-term recoveries (n = 3587) of tagged red drum Sciaenops ocellatus to directly estimate age- and length-based selectivity patterns using generalized linear models. The most parsimonious models were selected using AIC, and standard deviations were estimated using simulations. Selectivity of red drum was dependent upon the regulation period in which the fish was caught, the gear used to catch the fish (i.e., hook-and-line, gill nets, pound nets), and the fate of the fish upon recovery (i.e., harvested or released); models including all first-order interactions between main effects outperformed models without interactions. Selectivity of harvested fish was generally dome-shaped and shifted toward larger, older fish in response to regulation changes. Selectivity of caught-and-released red drum was highest on the youngest and smallest fish in the early and middle regulation periods, but increased on larger, legal-sized fish in the late regulation period. These results suggest that catch-and-release mortality has consistently been high for small, young red drum, but has recently become more common in larger, older fish. This method of estimating selectivity from short-term tag recoveries is valuable because it is simpler than full tag-return models, and may be more robust because yearly fishing and natural mortality rates do not need to be modeled and estimated.

  1. On using a generalized linear model to downscale daily precipitation for the center of Portugal: an analysis of trends and extremes

    NASA Astrophysics Data System (ADS)

    Pulquério, Mário; Garrett, Pedro; Santos, Filipe Duarte; Cruz, Maria João

    2015-04-01

    Portugal is on a climate change hot spot region, where precipitation is expected to decrease with important impacts regarding future water availability. As one of the European countries affected more by droughts in the last decades, it is important to assess how future precipitation regimes will change in order to study its impacts on water resources. Due to the coarse scale of global circulation models, it is often needed to downscale climate variables to the regional or local scale using statistical and/or dynamical techniques. In this study, we tested the use of a generalized linear model, as implemented in the program GLIMCLIM, to downscale precipitation for the center of Portugal where the Tagus basin is located. An analysis of the method performance is done as well as an evaluation of future precipitation trends and extremes for the twenty-first century. Additionally, we perform the first analysis of the evolution of droughts in climate change scenarios by the Standardized Precipitation Index in the study area. Results show that GLIMCLIM is able to capture the precipitation's interannual variation and seasonality correctly. However, summer precipitation is considerably overestimated. Additionally, precipitation extremes are in general well recovered, but high daily rainfall may be overestimated, and dry spell lengths are not correctly recovered by the model. Downscaled projections show a reduction in precipitation between 19 and 28 % at the end of the century. Results indicate that precipitation extremes will decrease and the magnitude of droughts can increase up to three times in relation to the 1961-1990 period which can have strong ecological, social, and economic impacts.

  2. Pathways of the North Pacific Intermediate Water identified through the tangent linear and adjoint models of an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Fujii, Y.; Nakano, T.; Usui, N.; Matsumoto, S.; Tsujino, H.; Kamachi, M.

    2014-12-01

    This study develops a strategy for tracing a target water mass, and applies it to analyzing the pathway of the North Pacific Intermediate Water (NPIW) from the subarctic gyre to the northwestern part of the subtropical gyre south of Japan in a simulation of an ocean general circulation model. This strategy estimates the pathway of the water mass that travels from an origin to a destination area during a specific period using a conservation property concerning tangent linear and adjoint models. In our analysis, a large fraction of the low salinity origin water mass of NPIW initially comes from the Okhotsk or Bering Sea, flows through the southeastern side of the Kuril Islands, and is advected to the Mixed Water Region (MWR) by the Oyashio current. It then enters the Kuroshio Extension (KE) at the first KE ridge, and is advected eastward by the KE current. However, it deviates southward from the KE axis around 158°E over the Shatsky Rise, or around 170ºE on the western side of the Emperor Seamount Chain, and enters the subtropical gyre. It is finally transported westward by the recirculation flow. This pathway corresponds well to the shortcut route of NPIW from MWR to the region south of Japan inferred from analysis of the long-term freshening trend of NPIW observation.

  3. Development of the complex general linear model in the Fourier domain: application to fMRI multiple input-output evoked responses for single subjects.

    PubMed

    Rio, Daniel E; Rawlings, Robert R; Woltz, Lawrence A; Gilman, Jodi; Hommer, Daniel W

    2013-01-01

    A linear time-invariant model based on statistical time series analysis in the Fourier domain for single subjects is further developed and applied to functional MRI (fMRI) blood-oxygen level-dependent (BOLD) multivariate data. This methodology was originally developed to analyze multiple stimulus input evoked response BOLD data. However, to analyze clinical data generated using a repeated measures experimental design, the model has been extended to handle multivariate time series data and demonstrated on control and alcoholic subjects taken from data previously analyzed in the temporal domain. Analysis of BOLD data is typically carried out in the time domain where the data has a high temporal correlation. These analyses generally employ parametric models of the hemodynamic response function (HRF) where prewhitening of the data is attempted using autoregressive (AR) models for the noise. However, this data can be analyzed in the Fourier domain. Here, assumptions made on the noise structure are less restrictive, and hypothesis tests can be constructed based on voxel-specific nonparametric estimates of the hemodynamic transfer function (HRF in the Fourier domain). This is especially important for experimental designs involving multiple states (either stimulus or drug induced) that may alter the form of the response function.

  4. Generalized linear mixed model analysis of risk factors for contamination of moisture-enhanced pork with Campylobacter jejuni and Salmonella enterica Typhimurium.

    PubMed

    Wen, Xuesong; Li, Jing; Dickson, James S

    2014-10-01

    Translocation of foodborne pathogens into the interior tissues of pork through moisture enhancement may be of concern if the meat is undercooked. In the present study, a five-strain mixture of Campylobacter jejuni or Salmonella enterica Typhimurium was evenly spread on the surface of fresh pork loins. Pork loins were injected, sliced, vacuum packaged, and stored. After storage, sliced pork was cooked by traditional grilling. Survival of Salmonella Typhimurium and C. jejuni in the interior tissues of the samples were analyzed by enumeration. The populations of these pathogens dropped below the detection limit (10 colony-forming units/g) in most samples that were cooked to 71.1°C or above. The general linear mixed model procedure was used to model the association between risk factors and the presence/absence of these pathogens after cooking. Estimated regression coefficients associated with the fixed effects indicated that the recovery probability of Salmonella Typhimurium was negatively associated with increasing level of enhancement. The effects of moisture enhancement and cooking on the recovery probability of C. jejuni were moderated by storage temperature. Our findings will assist food processors and regulatory agencies with science-based evaluation of the current processing, storage condition, and cooking guideline for moisture-enhanced pork.

  5. Pathways of the North Pacific Intermediate Water identified through the tangent linear and adjoint models of an ocean general circulation model

    NASA Astrophysics Data System (ADS)

    Fujii, Yosuke; Nakano, Toshiya; Usui, Norihisa; Matsumoto, Satoshi; Tsujino, Hiroyuki; Kamachi, Masafumi

    2013-04-01

    This study develops a strategy for tracing a target water mass, and applies it to analyzing the pathway of the North Pacific Intermediate Water (NPIW) from the subarctic gyre to the northwestern part of the subtropical gyre south of Japan in a simulation of an ocean general circulation model. This strategy estimates the pathway of the water mass that travels from an origin to a destination area during a specific period using a conservation property concerning tangent linear and adjoint models. In our analysis, a large fraction of the low salinity origin water mass of NPIW initially comes from the Okhotsk or Bering Sea, flows through the southeastern side of the Kuril Islands, and is advected to the Mixed Water Region (MWR) by the Oyashio current. It then enters the Kuroshio Extension (KE) at the first KE ridge, and is advected eastward by the KE current. However, it deviates southward from the KE axis around 158°E over the Shatsky Rise, or around 170°E on the western side of the Emperor Seamount Chain, and enters the subtropical gyre. It is finally transported westward by the recirculation flow. This pathway corresponds well to the shortcut route of NPIW from MWR to the region south of Japan inferred from analysis of the long-term freshening trend of NPIW observation. Copyright 2013 John Wiley & Sons, Ltd.

  6. Mechanisms of change during group metacognitive therapy for repetitive negative thinking in primary and non-primary generalized anxiety disorder.

    PubMed

    McEvoy, Peter M; Erceg-Hurn, David M; Anderson, Rebecca A; Campbell, Bruce N C; Nathan, Paula R

    2015-10-01

    Repetitive negative thinking (RNT) is a transdiagnostic process that serves to maintain emotional disorders. Metacognitive theory suggests that positive and negative metacognitive beliefs guide the selection of RNT as a coping strategy which, in turn, increases psychological distress. The aim of this study was to test the indirect effect of metacognitive beliefs on psychological distress via RNT. Patients (N=52) with primary and non-primary generalized anxiety disorder attended a brief, six-week group metacognitive therapy program and completed measures of metacognitive beliefs, RNT, and symptoms at the first and final treatment sessions, and at a one-month follow-up. Prospective indirect effects models found that negative metacognitive beliefs (but not positive metacognitive beliefs) had a significant indirect effect on psychological distress via RNT. As predicted by metacognitive theory, targeting negative metacognitions in treatment appears to reduce RNT and, in turn, emotional distress. Further research using alternative measures at multiple time points during therapy is required to determine whether the absence of a relationship with positive metacognitive beliefs in this study was a consequence of (a) psychometric issues, (b) these beliefs only being relevant to a subgroup of patients, or (c) a lack of awareness early in treatment.

  7. How do general practitioners implement decision-making regarding COPD patients with exacerbations? An international focus group study

    PubMed Central

    Laue, Johanna; Melbye, Hasse; Halvorsen, Peder A; Andreeva, Elena A; Godycki-Cwirko, Maciek; Wollny, Anja; Francis, Nick A; Spigt, Mark; Kung, Kenny; Risør, Mette Bech

    2016-01-01

    Purpose To explore the decision-making of general practitioners (GPs) concerning treatment with antibiotics and/or oral corticosteroids and hospitalization for COPD patients with exacerbations. Methods Thematic analysis of seven focus groups with 53 GPs from urban and rural areas in Norway, Germany, Wales, Poland, Russia, the Netherlands, and Hong Kong. Results Four main themes were identified. 1) Dealing with medical uncertainty: the GPs aimed to make clear medical decisions and avoid unnecessary prescriptions and hospitalizations, yet this was challenged by uncertainty regarding the severity of the exacerbations and concerns about overlooking comorbidities. 2) Knowing the patient: contextual knowledge about the individual patient provided a supplementary framework to biomedical knowledge, allowing for more differentiated decision-making. 3) Balancing the patients’ perspective: the GPs considered patients’ experiential knowledge about their own body and illness as valuable in assisting their decision-making, yet felt that dealing with disagreements between their own and their patients’ perceptions concerning the need for treatment or hospitalization could be difficult. 4) Outpatient support and collaboration: both formal and informal caregivers and organizational aspects of the health systems influenced the decision-making, particularly in terms of mitigating potentially severe consequences of “wrong decisions” and concerning the negotiation of responsibilities. Conclusion Fear of overlooking severe comorbidity and of further deteriorating symptoms emerged as a main driver of GPs’ management decisions. GPs consider a holistic understanding of illness and the patients’ own judgment crucial to making reasonable decisions under medical uncertainty. Moreover, GPs’ decisions depend on the availability and reliability of other formal and informal carers, and the health care systems’ organizational and cultural code of conduct. Strengthening the

  8. Opipramol for the treatment of generalized anxiety disorder: a placebo-controlled trial including an alprazolam-treated group.

    PubMed

    Möller, H J; Volz, H P; Reimann, I W; Stoll, K D

    2001-02-01

    Opipramol, a drug widely prescribed in Germany, is a tricyclic compound with no reuptake-inhibiting properties. However, it has pronounced D2-, 5-HT2-, and H1-blocking potential and high affinity to sigma receptors (sigma-1 and sigma-2). In early controlled trials, anxiolytic effects were revealed. However, those studies were performed before the concept of generalized anxiety disorder (GAD) was established. Because of the interesting receptor-binding profile and promising results of the early clinical trials, the authors performed a state-of-the-art placebo-controlled trial using alprazolam as an active control. Three hundred seven outpatients with GAD were included. After a 7-day single-blind placebo washout, patients were randomly assigned to receive either opipramol (final dose, 200 mg/day), alprazolam (2 mg/day), or placebo and were treated for 28 days. The efficacy of both active compounds was higher than the effects with placebo treatment. There were statistically significant differences (p < 0.05, according to the analysis of covariance) in the main outcome criterion (baseline-adjusted final means of an intent-to-treat analysis of the total scores on the Hamilton Rating Scale for Anxiety) and in secondary efficacy parameters, with global improvement of 47% for placebo and significantly more for opipramol (63%) and alprazolam (64%). Regarding safety and tolerability, no substantial differences in the number of adverse events observed between treatment groups were obvious. Sedation seemed more pronounced with alprazolam treatment than with opipramol or placebo. In this trial, it was demonstrated for the first time that opipramol, a strong but nonselective sigma site ligand, possesses anxiolytic efficacy superior to placebo in the treatment of GAD.

  9. A semiparametric negative binomial generalized linear model for modeling over-dispersed count data with a heavy tail: Characteristics and applications to crash data.

    PubMed

    Shirazi, Mohammadali; Lord, Dominique; Dhavala, Soma Sekhar; Geedipally, Srinivas Reddy

    2016-06-01

    Crash data can often be characterized by over-dispersion, heavy (long) tail and many observations with the value zero. Over the last few years, a small number of researchers have started developing and applying novel and innovative multi-parameter models to analyze such data. These multi-parameter models have been proposed for overcoming the limitations of the traditional negative binomial (NB) model, which cannot handle this kind of data efficiently. The research documented in this paper continues the work related to multi-parameter models. The objective of this paper is to document the development and application of a flexible NB generalized linear model with randomly distributed mixed effects characterized by the Dirichlet process (NB-DP) to model crash data. The objective of the study was accomplished using two datasets. The new model was compared to the NB and the recently introduced model based on the mixture of the NB and Lindley (NB-L) distributions. Overall, the research study shows that the NB-DP model offers a better performance than the NB model once data are over-dispersed and have a heavy tail. The NB-DP performed better than the NB-L when the dataset has a heavy tail, but a smaller percentage of zeros. However, both models performed similarly when the dataset contained a large amount of zeros. In addition to a greater flexibility, the NB-DP provides a clustering by-product that allows the safety analyst to better understand the characteristics of the data, such as the identification of outliers and sources of dispersion.

  10. Multitemporal Modelling of Socio-Economic Wildfire Drivers in Central Spain between the 1980s and the 2000s: Comparing Generalized Linear Models to Machine Learning Algorithms

    PubMed Central

    Vilar, Lara; Gómez, Israel; Martínez-Vega, Javier; Echavarría, Pilar; Riaño, David; Martín, M. Pilar

    2016-01-01

    The socio-economic factors are of key importance during all phases of wildfire management that include prevention, suppression and restoration. However, modeling these factors, at the proper spatial and temporal scale to understand fire regimes is still challenging. This study analyses socio-economic drivers of wildfire occurrence in central Spain. This site represents a good example of how human activities play a key role over wildfires in the European Mediterranean basin. Generalized Linear Models (GLM) and machine learning Maximum Entropy models (Maxent) predicted wildfire occurrence in the 1980s and also in the 2000s to identify changes between each period in the socio-economic drivers affecting wildfire occurrence. GLM base their estimation on wildfire presence-absence observations whereas Maxent on wildfire presence-only. According to indicators like sensitivity or commission error Maxent outperformed GLM in both periods. It achieved a sensitivity of 38.9% and a commission error of 43.9% for the 1980s, and 67.3% and 17.9% for the 2000s. Instead, GLM obtained 23.33, 64.97, 9.41 and 18.34%, respectively. However GLM performed steadier than Maxent in terms of the overall fit. Both models explained wildfires from predictors such as population density and Wildland Urban Interface (WUI), but differed in their relative contribution. As a result of the urban sprawl and an abandonment of rural areas, predictors like WUI and distance to roads increased their contribution to both models in the 2000s, whereas Forest-Grassland Interface (FGI) influence decreased. This study demonstrates that human component can be modelled with a spatio-temporal dimension to integrate it into wildfire risk assessment. PMID:27557113

  11. Atlas-guided volumetric diffuse optical tomography enhanced by generalized linear model analysis to image risk decision-making responses in young adults

    PubMed Central

    Lin, Zi-Jing; Li, Lin; Cazzell, Mary; Liu, Hanli

    2014-01-01

    Diffuse optical tomography (DOT) is a variant of functional near infrared spectroscopy and has the capability of mapping or reconstructing three dimensional (3D) hemodynamic changes due to brain activity. Common methods used in DOT image analysis to define brain activation have limitations because the selection of activation period is relatively subjective. General linear model (GLM)-based analysis can overcome this limitation. In this study, we combine the atlas-guided 3D DOT image reconstruction with GLM-based analysis (i.e., voxel-wise GLM analysis) to investigate the brain activity that is associated with risk decision-making processes. Risk decision-making is an important cognitive process and thus is an essential topic in the field of neuroscience. The Balloon Analog Risk Task (BART) is a valid experimental model and has been commonly used to assess human risk-taking actions and tendencies while facing risks. We have used the BART paradigm with a blocked design to investigate brain activations in the prefrontal and frontal cortical areas during decision-making from 37 human participants (22 males and 15 females). Voxel-wise GLM analysis was performed after a human brain atlas template and a depth compensation algorithm were combined to form atlas-guided DOT images. In this work, we wish to demonstrate the excellence of using voxel-wise GLM analysis with DOT to image and study cognitive functions in response to risk decision-making. Results have shown significant hemodynamic changes in the dorsal lateral prefrontal cortex (DLPFC) during the active-choice mode and a different activation pattern between genders; these findings correlate well with published literature in functional magnetic resonance imaging (fMRI) and fNIRS studies. PMID:24619964

  12. Women have relatively larger brains than men: a comment on the misuse of general linear models in the study of sexual dimorphism.

    PubMed

    Forstmeier, Wolfgang

    2011-11-01

    General linear models (GLM) have become such universal tools of statistical inference, that their applicability to a particular data set is rarely questioned. These models are designed to minimize residuals along the y-axis, while assuming that the predictor (x-axis) is free of statistical noise (ordinary least square regression, OLS). However, in practice, this assumption is often violated, which can lead to erroneous conclusions, particularly when two predictors are correlated with each other. This is best illustrated by two examples from the study of allometry, which have received great interest: (1) the question of whether men or women have relatively larger brains after accounting for body size differences, and (2) whether men indeed have shorter index fingers relative to ring fingers (digit ratio) than women. In depth analysis of these examples clearly shows that GLMs produce spurious sexual dimorphism in body shape where there is none (e.g. relative brain size). Likewise, they may fail to detect existing sexual dimorphisms in which the larger sex has the lower trait values (e.g. digit ratio) and, conversely, tend to exaggerate sexual dimorphism in which the larger sex has the relatively larger trait value (e.g. most sexually selected traits). These artifacts can be avoided with reduced major axis regression (RMA), which simultaneously minimizes residuals along both the x and the y-axis. Alternatively, in cases where isometry can be established there are no objections against and good reasons for the continued use of ratios as a simple means of correcting for size differences.

  13. Guanidinium groups act as general-acid catalysts in phosphoryl transfer reactions: a two-proton inventory on a model system.

    PubMed

    Piatek, Anna M; Gray, Mark; Anslyn, Eric V

    2004-08-18

    Cleavage/transesterification of phosphodiesters is catalyzed by various acidic groups in solution and with enzymes. General-acid catalysts can transfer protons to the developing phosphorane intermediate, resulting in a monoprotic-monoanionic intermediate, giving the so-called "triester mechanism". Using a proton inventory on a model compound (1) possessing an intramolecular hydrogen bond between a phosphodiester and a guanidinium group, we find that two protons move in the rate-determining step for cleavage/transesterification. In contrast, HPNP shows a single-proton inventory and is a substrate well accepted to react with the movement of only one proton at the transition state. We therefore propose a mechanism for 1 that involves general-acid catalysis by the guanidinium group. This leads one to conclude that other, more acidic groups, such as ammonium and imidazolium, would also act as general-acid catalysts.

  14. Prevalence of antimicrobial resistance in enteric Escherichia coli from domestic pets and assessment of associated risk markers using a generalized linear mixed model.

    PubMed

    Leite-Martins, Liliana R; Mahú, Maria I M; Costa, Ana L; Mendes, Angelo; Lopes, Elisabete; Mendonça, Denisa M V; Niza-Ribeiro, João J R; de Matos, Augusto J F; da Costa, Paulo Martins

    2014-11-01

    Antimicrobial resistance (AMR) is a growing global public health problem, which is caused by the use of antimicrobials in both human and animal medical practice. The objectives of the present cross-sectional study were as follows: (1) to determine the prevalence of resistance in Escherichia coli isolated from the feces of pets from the Porto region of Portugal against 19 antimicrobial agents and (2) to assess the individual, clinical and environmental characteristics associated with each pet as risk markers for the AMR of the E. coli isolates. From September 2009 to May 2012, rectal swabs were collected from pets selected using a systematic random procedure from the ordinary population of animals attending the Veterinary Hospital of Porto University. A total of 78 dogs and 22 cats were sampled with the objective of isolating E. coli. The animals' owners, who allowed the collection of fecal samples from their pets, answered a questionnaire to collect information about the markers that could influence the AMR of the enteric E. coli. Chromocult tryptone bile X-glucuronide agar was used for E. coli isolation, and the disk diffusion method was used to determine the antimicrobial susceptibility. The data were analyzed using a multilevel, univariable and multivariable generalized linear mixed model (GLMM). Several (49.7%) of the 396 isolates obtained in this study were multidrug-resistant. The E. coli isolates exhibited resistance to the antimicrobial agent's ampicillin (51.3%), cephalothin (46.7%), tetracycline (45.2%) and streptomycin (43.4%). Previous quinolone treatment was the main risk marker for the presence of AMR for 12 (ampicillin, cephalothin, ceftazidime, cefotaxime, nalidixic acid, ciprofloxacin, gentamicin, tetracycline, streptomycin, chloramphenicol, trimethoprim-sulfamethoxazole and aztreonam) of the 15 antimicrobials assessed. Coprophagic habits were also positively associated with an increased risk of AMR for six drugs, ampicillin, amoxicillin

  15. Does a research group increase impact on the scientific community or general public discussion? Alternative metric-based evaluation

    PubMed Central

    De Gregori, Manuela; Scotti, Valeria; De Silvestri, Annalisa; Curti, Moreno; Fanelli, Guido; Allegri, Massimo; Schatman, Michael E

    2016-01-01

    In this study, we investigated the impact of scientific publications of the Italian SIMPAR (Study In Multidisciplinary PAin Research) group by using altmetrics, defined as nontraditional metrics constituting an alternative to more traditional citation-impact metrics, such as impact factor and H-index. By correlating traditional and alternative metrics, we attempted to verify whether publications by the SIMPAR group collectively had more impact than those performed by its individual members, either in solo publications or in publications coauthored by non-SIMPAR group investigators (which for the purpose of this study we will refer to as “individual publications”). For all the 12 members of the group analyzed (pain therapists, biologists, and pharmacologists), we created Open Researcher and Contributor ID and Impact Story accounts, and synchronized these data. Manually, we calculated the level metrics for each article by dividing the data obtained from the research community by those obtained from the public community. We analyzed 759 articles, 18 of which were published by the SIMPAR group. Altmetrics demonstrated that SIMPAR group publications were more likely to be saved (77.8% vs 45.9%), discussed (61.1% vs 1.1%, P<0.0001), and publicly viewed (11.1% vs 1.3%, P=0.05) than individual publications. These results support the importance of multidisciplinary research groups in the impact of scientific literature; the interaction and synergy among the research participants allowed the obtainment of high impact-literature in the field of personalized pain medicine. Finally, our findings demonstrate the potential of altmetrics in estimating the value of the research products of a group. PMID:27358575

  16. Does a research group increase impact on the scientific community or general public discussion? Alternative metric-based evaluation.

    PubMed

    De Gregori, Manuela; Scotti, Valeria; De Silvestri, Annalisa; Curti, Moreno; Fanelli, Guido; Allegri, Massimo; Schatman, Michael E

    2016-01-01

    In this study, we investigated the impact of scientific publications of the Italian SIMPAR (Study In Multidisciplinary PAin Research) group by using altmetrics, defined as nontraditional metrics constituting an alternative to more traditional citation-impact metrics, such as impact factor and H-index. By correlating traditional and alternative metrics, we attempted to verify whether publications by the SIMPAR group collectively had more impact than those performed by its individual members, either in solo publications or in publications coauthored by non-SIMPAR group investigators (which for the purpose of this study we will refer to as "individual publications"). For all the 12 members of the group analyzed (pain therapists, biologists, and pharmacologists), we created Open Researcher and Contributor ID and Impact Story accounts, and synchronized these data. Manually, we calculated the level metrics for each article by dividing the data obtained from the research community by those obtained from the public community. We analyzed 759 articles, 18 of which were published by the SIMPAR group. Altmetrics demonstrated that SIMPAR group publications were more likely to be saved (77.8% vs 45.9%), discussed (61.1% vs 1.1%, P<0.0001), and publicly viewed (11.1% vs 1.3%, P=0.05) than individual publications. These results support the importance of multidisciplinary research groups in the impact of scientific literature; the interaction and synergy among the research participants allowed the obtainment of high impact-literature in the field of personalized pain medicine. Finally, our findings demonstrate the potential of altmetrics in estimating the value of the research products of a group.

  17. A General Chemistry and Precalculus First-Year Interest Group (FIG): Effect on Retention, Skills, and Attitudes

    ERIC Educational Resources Information Center

    Pence, Laura E.; Workman, Harry J.; Haruta, Mako E.

    2005-01-01

    The backdrop of the calculus reform movement created a fertile movement for the creation of overlap between general chemistry and precalculus as many of the goals emphasized key concepts from the chemistry lab. By using the graphing calculator in both precalculus and chemistry laboratory enhanced the students' comfort and competence with the…

  18. Linear drug eruption.

    PubMed

    Alfonso, R; Belinchon, I

    2001-01-01

    Linear eruptions are sometimes associated with systemic diseases and they may also be induced by various drugs. Paradoxically, such acquired inflammatory skin diseases tend to follow the system of Blaschko's lines. We describe a case of unilateral linear drug eruption caused by ibuprofen, which later became bilateral and generalized.

  19. A general entry to linear, dendritic and branched thiourea-linked glycooligomers as new motifs for phosphate ester recognition in water.

    PubMed

    Jiménez Blanco, José L; Bootello, Purificación; Ortiz Mellet, Carmen; Gutiérrez Gallego, Ricardo; García Fernández, José M

    2004-01-07

    A blockwise iterative synthetic strategy for the preparation of linear, dendritic and branched full-carbohydrate architectures has been developed by using sugar azido(carbamate) isothiocyanates as key templates; the presence of intersaccharide thiourea bridges provides anchoring points for hydrogen bond-directed molecular recognition of phosphate esters in water.

  20. A Generalization of Pythagoras's Theorem and Application to Explanations of Variance Contributions in Linear Models. Research Report. ETS RR-14-18

    ERIC Educational Resources Information Center

    Carlson, James E.

    2014-01-01

    Many aspects of the geometry of linear statistical models and least squares estimation are well known. Discussions of the geometry may be found in many sources. Some aspects of the geometry relating to the partitioning of variation that can be explained using a little-known theorem of Pappus and have not been discussed previously are the topic of…

  1. On the perturbation of the group generalized inverse for a class of bounded operators in Banach spaces

    NASA Astrophysics Data System (ADS)

    Castro-González, N.; Vélez-Cerrada, J. Y.

    2008-05-01

    Given a bounded operator A on a Banach space X with Drazin inverse AD and index r, we study the class of group invertible bounded operators B such that I+AD(B-A) is invertible and . We show that they can be written with respect to the decomposition as a matrix operator, , where B1 and are invertible. Several characterizations of the perturbed operators are established, extending matrix results. We analyze the perturbation of the Drazin inverse and we provide explicit upper bounds of ||B#-AD|| and ||BB#-ADA||. We obtain a result on the continuity of the group inverse for operators on Banach spaces.

  2. Separation and Identification of a Mixture of Group 6 Transition-Metal Carbonyl Compounds Using GC-MS in the General Chemistry Curriculum

    ERIC Educational Resources Information Center

    Fong, Lawrence K.

    2004-01-01

    Students in the general chemistry course are advised to scrutinize data obtained by gas chromatograph (GC) for segregation, and mass spectroscopy (MS) for recognizing combination of group 6 transition-metal carbonyl compounds. The GC-MS method arouses students' interest, as it can be applied to real-world situations, such as the routine…

  3. Exploring the Knowledge, Attitudes, Beliefs, and Communication Preferences of the General Public regarding HPV: Findings from CDC Focus Group Research and Implications for Practice

    ERIC Educational Resources Information Center

    Friedman, Allison L.; Shepeard, Hilda

    2007-01-01

    Genital human papillomavirus (HPV) infection is the most common sexually transmitted virus in the United States, causing genital warts, cervical cell abnormalities, and cervical cancer in women. To inform HPV education efforts, 35 focus groups were conducted with members of the general public, stratified by gender, race/ethnicity, and urban/rural…

  4. Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups

    ERIC Educational Resources Information Center

    Lieberman, Lauren; Lucas, Mark; Jones, Jeffery; Humphreys, Dan; Cody, Ann; Vaughn, Bev; Storms, Tommie

    2013-01-01

    "Helping General Physical Educators and Adapted Physical Educators Address the Office of Civil Rights Dear Colleague Guidance Letter: Part IV--Sport Groups" provides the the following articles: (1) "Sport Programming Offered by Camp Abilities and the United States Association for Blind Athletes" (Lauren Lieberman and Mark…

  5. Certain generalizations regarding the behavior of group components of shale oil in thermal processing, on the basis of derivatographic analysis

    SciTech Connect

    Georgiev, I.

    1992-05-20

    Derivatographic analysis is a frequently used method for obtaining supplementary information on the structure, structural changes, and processes taking place in thermal processing of substances. It is also extensively in studying solid fuels. The work reported here was aimed at studying the changes taking place under the conditions of derivatographic analysis in the group components of the residue (distilling above 350{degrees}C) from the liquid product obtained after thermal breakdown of Bulgarian oil shales in a unit with a solid heat-carrier. The group components - oils, resins, and asphaltenes - were obtained by separating the residue by means of procedures given. The derivatographic studies were performed in Paulik-Paulik-Erdey MOM apparatus in an inert medium with a heating rate of 6{degrees}/min, and DTA 1/10, DTG 1/10, and TG 1000 mg. 8 refs., 3 figs.

  6. GENERAL: Symmetry Reductions and Group-Invariant Solutions of (2 + 1)-Dimensional Caudrey-Dodd-Gibbon-Kotera-Sawada Equation

    NASA Astrophysics Data System (ADS)

    Lü, Na; Mei, Jian-Qin; Zhang, Hong-Qing

    2010-04-01

    With the aid of symbolic computation, we present the symmetry transformations of the (2 + 1)-dimensional Caudrey-Dodd-Gibbon-Kotera-Sawada equation with Lou's direct method that is based on Lax pairs. Moreover, with the symmetry transformations we obtain the Lie point symmetries of the CDGKS equation, and reduce the equation with the obtained symmetries. As a result, three independent reductions are presented and some group-invariant solutions of the equation are given.

  7. Spatio-temporal Rasch analysis of quality of life outcomes in the French general population. Measurement invariance and group comparisons

    PubMed Central

    2012-01-01

    Background This study aims at analyzing Health related quality of life (HRQoL) data on the French general population between 1995 and 2003 using an Item Response Theory (IRT) model. Methods Data concerned 26388 individuals having responded to the SF36 questionnaire in 1995 or in 2003. General Health, Mental Health and Physical Functioning dimensions have been analyzed using a latent regression mixed Partial Credit Model. Differential Item Functioning (DIF) have been searched on each item between age categories, genders, regions of residency, and years of study. Mean and variance of the latent traits have been explained by the same variables, in order to quantify their impact. Results Few DIF have been detected between age categories or genders. The analysis shows already known evolutions for HRQoL data: the decrease with age and the differences between genders with worst values for women. We note differences between regions, with better mean value in Paris, in the West or in the South of France, and worst values in the North and in the East. Last, a decrease of the three studied dimensions is noted between 1995 and 2003. Conclusions This study using IRT model offers several advantages compared to a classical approach based on scores. First, DIF can be taken into account. More, handling of missing data is easy, because IRT models do not required imputation of missing data. Last, analysis using IRT model is more powerful than analysis based on scores, and allow highlighting a most important number of effects. PMID:23190935

  8. The Effectiveness of Group Training of CBT-Based Stress Management on Anxiety, Psychological Hardiness and General Self-Efficacy among University Students

    PubMed Central

    Jafar, Hamdam Molla; Salabifard, Seddigheh; Mousavi, Seyedeh Maryam; Sobhani, Zahra

    2016-01-01

    Background: Admission to university is a very sensitive period of life for efficient, active, and young workforces in any country, and it is mostly associated with many changes in social and human relationships. These changes lead to anxiety in students. Moreover, humans need certain functions in order to adaptively deal with different life situations and challenges. By training stress management, these functions can help human acquire the required abilities. Objective: The present study was aimed at investigating the effectiveness of stress management training in anxiety, psychological hardiness, and general self-efficacy among university students. Method: The study was a quasi-experimental intervention (pretest-posttest-follow-up) including a control group, it was a fundamental applied study. The statistical population consisted of all students of Islamic Azad University, Karaj, Iran. Convenient sampling was employed to select 30 students who were divided into an experimental group (n=15) and a control group (n=15). Before stress management training, both groups filled out Beck Anxiety Inventory, Long and Goulet scale of psychological hardiness, and General Self-efficacy Scale (GSE-10). Afterwards, the experimental group was provided with stress management training. And after the experiment, the abovementioned questionnaires and scales were responded by the two groups. Finally the collected data were analyzed and compared using one-way MANOVA. Results: The results of MANOVA indicated that there was a significant difference between the two groups in terms of anxiety, hardiness, and general self-efficacy (p<0.001). Conclusion: According to the results of the present study and those of previous investigations that are in agreement with those of the present study, it can be concluded that stress management among university students cause anxiety to drop; moreover, it enhances their psychological hardiness and self-efficacy. In regard with the role and importance of

  9. Frequency regulators for the nonperturbative renormalization group: A general study and the model A as a benchmark

    NASA Astrophysics Data System (ADS)

    Duclut, Charlie; Delamotte, Bertrand

    2017-01-01

    We derive the necessary conditions for implementing a regulator that depends on both momentum and frequency in the nonperturbative renormalization-group flow equations of out-of-equilibrium statistical systems. We consider model A as a benchmark and compute its dynamical critical exponent z . This allows us to show that frequency regulators compatible with causality and the fluctuation-dissipation theorem can be devised. We show that when the principle of minimal sensitivity (PMS) is employed to optimize the critical exponents η , ν , and z , the use of frequency regulators becomes necessary to make the PMS a self-consistent criterion.

  10. A Functional Generalization of the Field-Theoretical Renormalization Group Approach for the Single-Impurity Anderson Model

    NASA Astrophysics Data System (ADS)

    Freire, Hermann; Corrêa, Eberth

    2012-02-01

    We apply a functional implementation of the field-theoretical renormalization group (RG) method up to two loops to the single-impurity Anderson model. To achieve this, we follow a RG strategy similar to that proposed by Vojta et al. (in Phys. Rev. Lett. 85:4940, 2000), which consists of defining a soft ultraviolet regulator in the space of Matsubara frequencies for the renormalized Green's function. Then we proceed to derive analytically and solve numerically integro-differential flow equations for the effective couplings and the quasiparticle weight of the present model, which fully treat the interplay of particle-particle and particle-hole parquet diagrams and the effect of the two-loop self-energy feedback into them. We show that our results correctly reproduce accurate numerical renormalization group data for weak to slightly moderate interactions. These results are in excellent agreement with other functional Wilsonian RG works available in the literature. Since the field-theoretical RG method turns out to be easier to implement at higher loops than the Wilsonian approach, higher-order calculations within the present approach could improve further the results for this model at stronger couplings. We argue that the present RG scheme could thus offer a possible alternative to other functional RG methods to describe electronic correlations within this model.

  11. [2-stage group psychotherapy with integrated autogenic training within the scope of a general integrated psychotherapy concept].

    PubMed

    Barolin, Gerhard S

    2003-01-01

    Group-therapy and autogenic training in combination show mutual potentiation. Our results have proved the hypothesis to be true and we have also been able to explain it by an analysis of the neurophysiological and psychological findings concerning both methods. Our "model" has proved to be very economical in time and can be easily applied. It needs basic psychotherapeutical education but no special additive schooling. It is particularly well employed in rehabilitation patients, elderly patients and geronto-rehabilitation patients. As numbers of such patients are steadily increasing, it could soon become highly important, and in the technically dominated medicine of today, the particularly communicative component that we postulate in integrated psychotherapy could also grow in importance. By combining the two methods, it is not method that is at the centre of our endeavours but the patient.

  12. High-Risk groups for late diagnosis of HIV infection: a need for rethinking testing policy in the general population.

    PubMed

    Delpierre, Cyrille; Cuzin, Lise; Lauwers-Cances, Valérie; Marchou, Bruno; Lang, Thierry

    2006-12-01

    The aim of the study was to identify high-risk groups and the determinants of late HIV diagnosis in France in the era of highly active antiretroviral therapy (HAART), from January 1996 to June 2005. Informations were collected from an electronic medical record of all HIV- 1-infected patients who sought care in six HIV reference centers in France, constituting a prospective multicentric cohort. Patients were defined as "late testers" if they had presented with either symptoms of clinical AIDS or a CD4 cell count less than 200/mm(3) during the year of diagnosis, as "nonlate" if their CD4 count was above 200, and as "unknown" if CD4 cell count in the year at the time of diagnosis was not documented. Among the 4516 patients available for analysis, the percentage of late testing was 38% (n = 1718) and decreased after 2003 (31.5% in 2004-2005). This percentage was higher in heterosexual men (48.2%) than in homosexual men (31.7%) or heterosexual women (32.6%) and was higher for patients older than 30. Heterosexual men living in a couple with children had a higher risk of late testing (odds ratio [OR] = 1.65, 95% confidence interval [CI]: 1.03 to 2.66), while heterosexual women in a couple without children had a lower risk (OR = 0.46, 95% CI: 0.25 to 0.83). Among homosexual men, unemployment was associated with late testing (OR = 2.23, 95% CI: 1.14 to 4.36). The proportion of late testing was still high. Groups classically identified as low risk for HIV infection, particularly heterosexual men in a couple with children, were found to be at high risk for late testing. It seems necessary to improve HIV testing policy in the heterosexual population.

  13. Practice-based small group learning (PBSGL) for CPD: a pilot with general practice trainees to support the transition to independent practice.

    PubMed

    Rial, Jonathan; Scallan, Samantha

    2013-05-01

    The paper describes a small-scale enquiry with UK-based general practice specialty trainees (GPSTs) at the time of transition from training to independent practice. It aimed to identify whether they were supported in making this transition through attending practice-based small group learning (PBSGL) sessions. Participants in the study reported that the sessions helped them to consolidate their learning from their third year of training (GPST3), improved their ability to identify and use evidence in practice, and shifted the focus of their learning needs away from the two UK general practice postgraduate exams (applied Knowledge Test or aKT; and Clinical Skills assessment or CSa) and towards 'real world' practice. The two pilot groups have become established as means of peer support and continue to meet, with small changes in composition. The work has led to the wider roll out of PBSGL for newly qualified GPs across Wessex.

  14. Tobacco Smoking in HIV-Infected versus General Population in France: Heterogeneity across the Various Groups of People Living with HIV

    PubMed Central

    Tron, Laure; Lert, France; Spire, Bruno; Dray-Spira, Rosemary

    2014-01-01

    Background Although the various groups of people living with HIV (PLWHIV) considerably differ regarding socioeconomic and behavioral characteristics, their specificities regarding tobacco smoking have been poorly investigated. We aimed to assess patterns of tobacco consumption across the various groups of PLWHIV and to compare them to the general population, accounting for the specific socioeconomic profile of PLWHIV. Methods We used data of the ANRS-Vespa2 study, a national representative survey on PLWHIV conducted in France in 2011. Prevalence of past and current tobacco consumption, heavy smoking and strong nicotine dependence were assessed among the various groups of PLWHIV as defined by transmission category, gender and geographic origin, and compared to the French general population using direct standardization and multivariate Poisson regression models, accounting for gender, age, education and geographic origin. Results Among the 3,019 participants aged 18–85 years (median time since HIV diagnosis: 12 years), 37.5% were current smokers and 22.1% were past smokers, with marked differences across the various groups of PLWHIV. Compared to the general population, the prevalence of regular smoking was increased among HIV-infected men who have sex with men (MSM) (adjusted prevalence rate ratio (aPRR): 1.19, 95% confidence interval (95% CI): 1.07–1.32), French-native women (aPRR: 1.32, 95% CI: 1.10–1.57), and heterosexual French-native men (although not significantly, aPRR: 1.19, 95% CI: 0.98–1.45). Additionally, HIV-infected MSM were significantly less likely to be ex-smokers (aPRR: 0.73, 95% CI: 0.64–0.82) than the general population and similar trends were observed among heterosexual French-native men (aPRR: 0.89, 95% CI: 0.78–1.02) and women (aPRR: 0.84, 95% CI: 0.70–1.01). HIV-infected sub-Saharan African migrants were less likely to be regular smokers than the general population. Conclusions Smoking constitutes a major concern in various groups

  15. PaTz groups for primary palliative care: reinventing cooperation between general practitioners and district nurses in palliative care: an evaluation study combining data from focus groups and a questionnaire

    PubMed Central

    2014-01-01

    Background PaTz (an acronym for ‘PAlliatieve Thuis Zorg’; palliative care at home) is an intervention to improve palliative care provision and strengthen the generalist knowledge of palliative care. In PaTz general practitioners and district nurses meet on a regular basis to identify patients with palliative care needs and to discuss care for these patients. This study explores experiences with regard to collaboration between general practitioners and district nurses, and perceived benefits of and barriers for implementation of PaTz. Methods This study is conducted within the primary care setting. Participants were 24 general practitioners who filled in a questionnaire, and seven general practitioners, five district nurses and two palliative care consultants who attended one of two focus groups. Results PaTz led to improved collaboration. Participants felt informational and emotional support from other PaTz participants. Also they felt that continuity of care was enhanced by PaTz. Practical recommendations for implementation were: meetings every 6 to 8 weeks, regular attendance from both general practitioners and district nurses, presence of a palliative care consultant, and a strong chairman. Conclusions PaTz is successful in enhancing collaboration in primary palliative care and easy to implement. Participants felt it improved continuity of care and knowledge on palliative care. Further research is needed to investigate whether patient and carer outcomes improve. PMID:24444024

  16. Conserving the linear momentum in stochastic dynamics: Dissipative particle dynamics as a general strategy to achieve local thermostatization in molecular dynamics simulations.

    PubMed

    Passler, Peter P; Hofer, Thomas S

    2017-02-15

    Stochastic dynamics is a widely employed strategy to achieve local thermostatization in molecular dynamics simulation studies; however, it suffers from an inherent violation of momentum conservation. Although this short-coming has little impact on structural and short-time dynamic properties, it can be shown that dynamics in the long-time limit such as diffusion is strongly dependent on the respective thermostat setting. Application of the methodically similar dissipative particle dynamics (DPD) provides a simple, effective strategy to ensure the advantages of local, stochastic thermostatization while at the same time the linear momentum of the system remains conserved. In this work, the key parameters to employ the DPD thermostats in the framework of periodic boundary conditions are investigated, in particular the dependence of the system properties on the size of the DPD-region as well as the treatment of forces near the cutoff. Structural and dynamical data for light and heavy water as well as a Lennard-Jones fluid have been compared to simulations executed via stochastic dynamics as well as via use of the widely employed Nose-Hoover chain and Berendsen thermostats. It is demonstrated that a small size of the DPD region is sufficient to achieve local thermalization, while at the same time artifacts in the self-diffusion characteristic for stochastic dynamics are eliminated. © 2016 Wiley Periodicals, Inc.

  17. A fractal model of HIV transmission on complex socio-geographic networks. Part 2: spread from a ghettoized 'core group' into a 'general population'.

    PubMed

    Wallace, R

    1994-01-01

    "Study of the initial stages of HIV transmission along a 'sociogeographic network'--a large, complex, spatially focused social network with possibly fractal geometry--is extended to include interaction between a low-dimensional ghettoized 'core group' within which the disease spreads very rapidly and a higher dimensional, more loosely structured 'general population' in which spread is relatively slow. A mathematical modeling exercise suggests that contextually modulated interaction between them can be highly nonlinear and may greatly increase the initial rate of disease transmission within the general population. This work contributes to a growing body of literature which suggests that programs to control HIV infection within the majority heterosexual population of the United States will fail spectacularly without particular focus on the coupled physical and social stabilization and rehabilitation of the urban ghettoes of marginalized populations which are the present, and rapidly expanding, disease epicenters. Evidence suggests their continued disintegration can both increase disease rates within the epicenters and increase the coupling between core groups and general populations by creating large numbers of spatially or economically displaced refugees."

  18. LINEAR ACCELERATOR

    DOEpatents

    Christofilos, N.C.; Polk, I.J.

    1959-02-17

    Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.

  19. Evidence of a general 2/3-power law of scaling leaf nitrogen to phosphorus among major plant groups and biomes

    PubMed Central

    Reich, Peter B.; Oleksyn, Jacek; Wright, Ian J.; Niklas, Karl J.; Hedin, Lars; Elser, James J.

    2010-01-01

    Scaling relations among plant traits are both cause and consequence of processes at organ-to-ecosystem scales. The relationship between leaf nitrogen and phosphorus is of particular interest, as both elements are essential for plant metabolism; their limited availabilities often constrain plant growth, and general relations between the two have been documented. Herein, we use a comprehensive dataset of more than 9300 observations of approximately 2500 species from 70 countries to examine the scaling of leaf nitrogen to phosphorus within and across taxonomical groups and biomes. Power law exponents derived from log–log scaling relations were near 2/3 for all observations pooled, for angiosperms and gymnosperms globally, and for angiosperms grouped by biomes, major functional groups, orders or families. The uniform 2/3 scaling of leaf nitrogen to leaf phosphorus exists along a parallel continuum of rising nitrogen, phosphorus, specific leaf area, photosynthesis and growth, as predicted by stoichiometric theory which posits that plants with high growth rates require both high allocation of phosphorus-rich RNA and a high metabolic rate to support the energy demands of macromolecular synthesis. The generality of this finding supports the view that this stoichiometric scaling relationship and the mechanisms that underpin it are foundational components of the living world. Additionally, although abundant variance exists within broad constraints, these results also support the idea that surprisingly simple rules regulate leaf form and function in terrestrial ecosystems. PMID:19906667

  20. Evidence of a general 2/3-power law of scaling leaf nitrogen to phosphorus among major plant groups and biomes.

    PubMed

    Reich, Peter B; Oleksyn, Jacek; Wright, Ian J; Niklas, Karl J; Hedin, Lars; Elser, James J

    2010-03-22

    Scaling relations among plant traits are both cause and consequence of processes at organ-to-ecosystem scales. The relationship between leaf nitrogen and phosphorus is of particular interest, as both elements are essential for plant metabolism; their limited availabilities often constrain plant growth, and general relations between the two have been documented. Herein, we use a comprehensive dataset of more than 9300 observations of approximately 2500 species from 70 countries to examine the scaling of leaf nitrogen to phosphorus within and across taxonomical groups and biomes. Power law exponents derived from log-log scaling relations were near 2/3 for all observations pooled, for angiosperms and gymnosperms globally, and for angiosperms grouped by biomes, major functional groups, orders or families. The uniform 2/3 scaling of leaf nitrogen to leaf phosphorus exists along a parallel continuum of rising nitrogen, phosphorus, specific leaf area, photosynthesis and growth, as predicted by stoichiometric theory which posits that plants with high growth rates require both high allocation of phosphorus-rich RNA and a high metabolic rate to support the energy demands of macromolecular synthesis. The generality of this finding supports the view that this stoichiometric scaling relationship and the mechanisms that underpin it are foundational components of the living world. Additionally, although abundant variance exists within broad constraints, these results also support the idea that surprisingly simple rules regulate leaf form and function in terrestrial ecosystems.

  1. Non-Linear Approach in Kinesiology Should Be Preferred to the Linear--A Case of Basketball.

    PubMed

    Trninić, Marko; Jeličić, Mario; Papić, Vladan

    2015-07-01

    In kinesiology, medicine, biology and psychology, in which research focus is on dynamical self-organized systems, complex connections exist between variables. Non-linear nature of complex systems has been discussed and explained by the example of non-linear anthropometric predictors of performance in basketball. Previous studies interpreted relations between anthropometric features and measures of effectiveness in basketball by (a) using linear correlation models, and by (b) including all basketball athletes in the same sample of participants regardless of their playing position. In this paper the significance and character of linear and non-linear relations between simple anthropometric predictors (AP) and performance criteria consisting of situation-related measures of effectiveness (SE) in basketball were determined and evaluated. The sample of participants consisted of top-level junior basketball players divided in three groups according to their playing time (8 minutes and more per game) and playing position: guards (N = 42), forwards (N = 26) and centers (N = 40). Linear (general model) and non-linear (general model) regression models were calculated simultaneously and separately for each group. The conclusion is viable: non-linear regressions are frequently superior to linear correlations when interpreting actual association logic among research variables.

  2. Parametric Identification of Systems Via Linear Operators.

    DTIC Science & Technology

    1978-09-01

    A general parametric identification /approximation model is developed for the black box identification of linear time invariant systems in terms of... parametric identification techniques derive from the general model as special cases associated with a particular linear operator. Some possible

  3. General theory for multiple input-output perturbations in complex molecular systems. 1. Linear QSPR electronegativity models in physical, organic, and medicinal chemistry.

    PubMed

    González-Díaz, Humberto; Arrasate, Sonia; Gómez-SanJuan, Asier; Sotomayor, Nuria; Lete, Esther; Besada-Porto, Lina; Ruso, Juan M

    2013-01-01

    In general perturbation methods starts with a known exact solution of a problem and add "small" variation terms in order to approach to a solution for a related problem without known exact solution. Perturbation theory has been widely used in almost all areas of science. Bhor's quantum model, Heisenberg's matrix mechanincs, Feyman diagrams, and Poincare's chaos model or "butterfly effect" in complex systems are examples of perturbation theories. On the other hand, the study of Quantitative Structure-Property Relationships (QSPR) in molecular complex systems is an ideal area for the application of perturbation theory. There are several problems with exact experimental solutions (new chemical reactions, physicochemical properties, drug activity and distribution, metabolic networks, etc.) in public databases like CHEMBL. However, in all these cases, we have an even larger list of related problems without known solutions. We need to know the change in all these properties after a perturbation of initial boundary conditions. It means, when we test large sets of similar, but different, compounds and/or chemical reactions under the slightly different conditions (temperature, time, solvents, enzymes, assays, protein targets, tissues, partition systems, organisms, etc.). However, to the best of our knowledge, there is no QSPR general-purpose perturbation theory to solve this problem. In this work, firstly we review general aspects and applications of both perturbation theory and QSPR models. Secondly, we formulate a general-purpose perturbation theory for multiple-boundary QSPR problems. Last, we develop three new QSPR-Perturbation theory models. The first model classify correctly >100,000 pairs of intra-molecular carbolithiations with 75-95% of Accuracy (Ac), Sensitivity (Sn), and Specificity (Sp). The model predicts probabilities of variations in the yield and enantiomeric excess of reactions due to at least one perturbation in boundary conditions (solvent, temperature

  4. Combined AIE/EBE/GMRES approach to incompressible flows. [Adaptive Implicit-Explicit/Grouped Element-by-Element/Generalized Minimum Residuals

    NASA Technical Reports Server (NTRS)

    Liou, J.; Tezduyar, T. E.

    1990-01-01

    Adaptive implicit-explicit (AIE), grouped element-by-element (GEBE), and generalized minimum residuals (GMRES) solution techniques for incompressible flows are combined. In this approach, the GEBE and GMRES iteration methods are employed to solve the equation systems resulting from the implicitly treated elements, and therefore no direct solution effort is involved. The benchmarking results demonstrate that this approach can substantially reduce the CPU time and memory requirements in large-scale flow problems. Although the description of the concepts and the numerical demonstration are based on the incompressible flows, the approach presented here is applicable to larger class of problems in computational mechanics.

  5. Extending the simple linear regression model to account for correlated responses: an introduction to generalized estimating equations and multi-level mixed modelling.

    PubMed

    Burton, P; Gurrin, L; Sly, P

    1998-06-15

    Much of the research in epidemiology and clinical science is based upon longitudinal designs which involve repeated measurements of a variable of interest in each of a series of individuals. Such designs can be very powerful, both statistically and scientifically, because they enable one to study changes within individual subjects over time or under varied conditions. However, this power arises because the repeated measurements tend to be correlated with one another, and this must be taken into proper account at the time of analysis or misleading conclusions may result. Recent advances in statistical theory and in software development mean that studies based upon such designs can now be analysed more easily, in a valid yet flexible manner, using a variety of approaches which include the use of generalized estimating equations, and mixed models which incorporate random effects. This paper provides a particularly simple illustration of the use of these two approaches, taking as a practical example the analysis of a study which examined the response of portable peak expiratory flow meters to changes in true peak expiratory flow in 12 children with asthma. The paper takes the reader through the relevant practicalities of model fitting, interpretation and criticism and demonstrates that, in a simple case such as this, analyses based upon these model-based approaches produce reassuringly similar inferences to standard analyses based upon more conventional methods.

  6. Solar System constraints on renormalization group extended general relativity: The PPN and Laplace-Runge-Lenz analyses with the external potential effect

    NASA Astrophysics Data System (ADS)

    Rodrigues, Davi C.; Mauro, Sebastião; de Almeida, Álefe O. F.

    2016-10-01

    General relativity extensions based on renormalization group effects are motivated by a known physical principle and constitute a class of extended gravity theories that have some unexplored unique aspects. In this work we develop in detail the Newtonian and post-Newtonian limits of a realization called renormalization group extended general relativity (RGGR). Special attention is given to the external potential effect, which constitutes a type of screening mechanism typical of RGGR. In the Solar System, RGGR depends on a single dimensionless parameter ν¯⊙, and this parameter is such that for ν¯⊙=0 one fully recovers GR in the Solar System. Previously this parameter was constrained to be |ν¯ ⊙|≲10-21 , without considering the external potential effect. Here we show that under a certain approximation RGGR can be cast in a form compatible with the parametrized post-Newtonian (PPN) formalism, and we use both the PPN formalism and the Laplace-Runge-Lenz technique to put new bounds on ν¯⊙, either considering or not the external potential effect. With the external potential effect the new bound reads |ν¯ ⊙|≲10-16 . We discuss the possible consequences of this bound on the dark matter abundance in galaxies.

  7. Le langage des espaces et des groupes quantiques

    NASA Astrophysics Data System (ADS)

    Maltsiniotis, Georges

    1993-01-01

    We study the foundations of the differential calculus in quantum geometry. The notions of (differential) quantum space and cone are introduced. Generalizing a construction of Manin, to a quantum cone we associate the quantum group of its “linear automorphisms preserving the differentials” and deduce a de Rham complex on this group. We give examples of differential calculi on quantum hyperplanes and quantum linear groups.

  8. 3-Year-Old Children Selectively Generalize Object Functions Following a Demonstration from a Linguistic In-group Member: Evidence from the Phenomenon of Scale Error

    PubMed Central

    Oláh, Katalin; Elekes, Fruzsina; Pető, Réka; Peres, Krisztina; Király, Ildikó

    2016-01-01

    The present study investigated 3-year-old children’s learning processes about object functions. We built on children’s tendency to commit scale errors with tools to explore whether they would selectively endorse object functions from a linguistic in-group over an out-group model. Participants (n = 37) were presented with different object sets, and a model speaking either in their native or a foreign language demonstrated how to use the presented tools. In the test phase, children received the object sets with two modifications: the original tool was replaced by one that was too big to achieve the goal but was otherwise identical, and another tool was added to the set that looked different but was appropriately scaled for goal attainment. Children in the Native language condition were significantly more likely to commit scale errors – that is, choose the over-sized tool – than children in the Foreign language condition (48 vs. 30%). We propose that these results provide insight into the characteristics of human-specific learning processes by showing that children are more likely to generalize object functions to a category of artifacts following a demonstration from an in-group member. PMID:27445925

  9. On the linear programming bound for linear Lee codes.

    PubMed

    Astola, Helena; Tabus, Ioan

    2016-01-01

    Based on an invariance-type property of the Lee-compositions of a linear Lee code, additional equality constraints can be introduced to the linear programming problem of linear Lee codes. In this paper, we formulate this property in terms of an action of the multiplicative group of the field [Formula: see text] on the set of Lee-compositions. We show some useful properties of certain sums of Lee-numbers, which are the eigenvalues of the Lee association scheme, appearing in the linear programming problem of linear Lee codes. Using the additional equality constraints, we formulate the linear programming problem of linear Lee codes in a very compact form, leading to a fast execution, which allows to efficiently compute the bounds for large parameter values of the linear codes.

  10. Generalized teleportation and entanglement recycling.

    PubMed

    Strelchuk, Sergii; Horodecki, Michał; Oppenheim, Jonathan

    2013-01-04

    We introduce new teleportation protocols which are generalizations of the original teleportation protocols that use the Pauli group and the port-based teleportation protocols, introduced by Hiroshima and Ishizaka, that use the symmetric permutation group. We derive sufficient conditions for a set of operations, which in general need not form a group, to give rise to a teleportation protocol and provide examples of such schemes. This generalization leads to protocols with novel properties and is needed to push forward new schemes of computation based on them. Port-based teleportation protocols and our generalizations use a large resource state consisting of N singlets to teleport only a single qubit state reliably. We provide two distinct protocols which recycle the resource state to teleport multiple states with error linearly increasing with their number. The first protocol consists of sequentially teleporting qubit states, and the second teleports them in a bulk.

  11. Generalized Teleportation and Entanglement Recycling

    NASA Astrophysics Data System (ADS)

    Strelchuk, Sergii; Horodecki, Michał; Oppenheim, Jonathan

    2013-01-01

    We introduce new teleportation protocols which are generalizations of the original teleportation protocols that use the Pauli group and the port-based teleportation protocols, introduced by Hiroshima and Ishizaka, that use the symmetric permutation group. We derive sufficient conditions for a set of operations, which in general need not form a group, to give rise to a teleportation protocol and provide examples of such schemes. This generalization leads to protocols with novel properties and is needed to push forward new schemes of computation based on them. Port-based teleportation protocols and our generalizations use a large resource state consisting of N singlets to teleport only a single qubit state reliably. We provide two distinct protocols which recycle the resource state to teleport multiple states with error linearly increasing with their number. The first protocol consists of sequentially teleporting qubit states, and the second teleports them in a bulk.

  12. Wei-Norman equations for classical groups

    NASA Astrophysics Data System (ADS)

    Charzyński, Szymon; Kuś, Marek

    2015-08-01

    We show that the nonlinear autonomous Wei-Norman equations, expressing the solution of a linear system of non-autonomous equations on a Lie algebra, can be reduced to the hierarchy of matrix Riccati equations in the case of all classical simple Lie algebras. The result generalizes our previous one concerning the complex Lie algebra of the special linear group. We show that it cannot be extended to all simple Lie algebras, in particular to the exceptional G2 algebra.

  13. Linear Programming Problems for Generalized Uncertainty

    ERIC Educational Resources Information Center

    Thipwiwatpotjana, Phantipa

    2010-01-01

    Uncertainty occurs when there is more than one realization that can represent an information. This dissertation concerns merely discrete realizations of an uncertainty. Different interpretations of an uncertainty and their relationships are addressed when the uncertainty is not a probability of each realization. A well known model that can handle…

  14. Linear derivative Cartan formulation of general relativity

    NASA Astrophysics Data System (ADS)

    Kummer, W.; Schütz, H.

    2005-07-01

    Beside diffeomorphism invariance also manifest SO(3,1) local Lorentz invariance is implemented in a formulation of Einstein gravity (with or without cosmological term) in terms of initially completely independent vielbein and spin connection variables and auxiliary two-form fields. In the systematic study of all possible embeddings of Einstein gravity into that formulation with auxiliary fields, the introduction of a “bi-complex” algebra possesses crucial technical advantages. Certain components of the new two-form fields directly provide canonical momenta for spatial components of all Cartan variables, whereas the remaining ones act as Lagrange multipliers for a large number of constraints, some of which have been proposed already in different, less radical approaches. The time-like components of the Cartan variables play that role for the Lorentz constraints and others associated to the vierbein fields. Although also some ternary ones appear, we show that relations exist between these constraints, and how the Lagrange multipliers are to be determined to take care of second class ones. We believe that our formulation of standard Einstein gravity as a gauge theory with consistent local Poincaré algebra is superior to earlier similar attempts.

  15. Generalized Ultrametric Semilattices of Linear Signals

    DTIC Science & Technology

    2014-01-23

    second edition, 2001. [10] Robert C. Flagg and Ralph Kopperman. Continuity spaces: Reconciling domains and metric spaces. Theoretical Computer Science, 177...point. Theoretical Computer Science, 238(1-2):483–488, 2000. [31] Alan V. Oppenheim , Alan S. Willsky, and S. Hamid Nawab. Signals & Systems. Prentice

  16. Missed opportunities to offer HIV tests to high-risk groups during general practitioners’ STI-related consultations: an observational study

    PubMed Central

    Joore, I K; Reukers, D F M; Donker, G A; van Sighem, A I; Op de Coul, E L M; Prins, J M; Geerlings, S E; Barth, R E; van Bergen, J E A M; van den Broek, I V

    2016-01-01

    Objectives Prior research has shown that Dutch general practitioners (GPs) do not always offer HIV testing and the number of undiagnosed HIV patients remains high. We aimed to further investigate the frequency and reasons for (not) testing for HIV and the contribution of GPs to the diagnosis of HIV infections in the Netherlands. Design Observational study. Setting (1) Dutch primary care network of 42–45 sentinel practices where report forms during sexually transmitted infection (STI)-related consultations were routinely collected, 2008–2013. (2) Dutch observational cohort with medical data of HIV-positive patients in HIV care, 2008–2013. Outcome measures The proportion of STI-related consultations in patients from high-risk groups tested for HIV, with additional information requested from GPs on HIV testing preconsultation or postconsultation for whom HIV testing was indicated, but not performed. Next, information was collected on the profile of HIV-positive patients entering specialised HIV care following diagnosis by GPs. Results Initially, an HIV test was reported (360/907) in 40% of STI-related consultations in high-risk groups. Additionally, in 26% of consultations an HIV test had been performed in previous or follow-up consultations or at different STI-care facilities. The main reasons for not testing were perceived insignificant risk; ‘too’ recent risk according to GPs or the reluctance of patients. The initiative of the patient was a strong determinant for HIV testing. GPs diagnosed about one third of all newly found cases of HIV. Compared with STI clinics, HIV-positive patients diagnosed in general practice were more likely to be older, female, heterosexual male or sub-Saharan African. Conclusions In one-third of the STI-related consultations of persons from high-risk groups, no HIV test was performed in primary care, which is lower than previously reported. Risk-based testing has intrinsic limitations and implementation of new additional

  17. Tobacco Use among U.S. Racial/Ethnic Minority Groups--African Americans, American Indians and Alaska Natives, Asian Americans and Pacific Islanders, and Hispanics: A Report of the Surgeon General. Executive Summary.

    ERIC Educational Resources Information Center

    Center for Chronic Disease Prevention and Health Promotion (DHHS/CDC), Atlanta, GA.

    Smoking is the leading cause of preventable death in the United States and certain racial and ethnic minority groups are at higher risk for using tobacco. This is the first Surgeon General's report to focus on tobacco use among these four racial and ethnic minority groups. It provides a single, comprehensive source of data on each group's pattern…

  18. LINEAR ACCELERATOR

    DOEpatents

    Colgate, S.A.

    1958-05-27

    An improvement is presented in linear accelerators for charged particles with respect to the stable focusing of the particle beam. The improvement consists of providing a radial electric field transverse to the accelerating electric fields and angularly introducing the beam of particles in the field. The results of the foregoing is to achieve a beam which spirals about the axis of the acceleration path. The combination of the electric fields and angular motion of the particles cooperate to provide a stable and focused particle beam.

  19. Linear Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03667 Linear Clouds

    These clouds are located near the edge of the south polar region. The cloud tops are the puffy white features in the bottom half of the image.

    Image information: VIS instrument. Latitude -80.1N, Longitude 52.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. System theory as applied differential geometry. [linear system

    NASA Technical Reports Server (NTRS)

    Hermann, R.

    1979-01-01

    The invariants of input-output systems under the action of the feedback group was examined. The approach used the theory of Lie groups and concepts of modern differential geometry, and illustrated how the latter provides a basis for the discussion of the analytic structure of systems. Finite dimensional linear systems in a single independent variable are considered. Lessons of more general situations (e.g., distributed parameter and multidimensional systems) which are increasingly encountered as technology advances are presented.

  1. Use of lipid-based nutrient supplements (LNS) to improve the nutrient adequacy of general food distribution rations for vulnerable sub-groups in emergency settings.

    PubMed

    Chaparro, Camila M; Dewey, Kathryn G

    2010-01-01

    The term 'lipid-based nutrient supplements' (LNS) refers generically to a range of fortified, lipid-based products, including products like Ready-to-Use Therapeutic Foods (RUTF) (a large daily ration with relatively low micronutrient concentration) as well as highly concentrated supplements (1-4 teaspoons/day, providing <100 kcal/day) to be used for 'point-of-use' fortification. RUTF have been successfully used for the management of severe acute malnutrition (SAM) among children in emergency settings. Recent research on smaller doses of LNS for prevention of malnutrition has created interest in their potential use in emergency settings to ensure a more nutritionally adequate ration for the most vulnerable groups [e.g. infants and children between 6 and 24 months of age, and pregnant and lactating women (PLW)]. Currently, the main food and nutrition interventions in emergency settings include general food distribution (GFD) rations, which are provided to the affected population as a whole, and selective (or supplementary) feeding programs (SFP), which are to be provided to nutritionally vulnerable or malnourished individuals. In addition to logistical and operational challenges that may limit the intended effect of these programs, the nutritional quality of the food commodities provided may be insufficient to meet the needs of infants and young children and PLW. Because these subgroups have particularly high nutrient needs for growth and development, meeting these needs is challenging in settings where the ration is limited to a few food commodities, with little access to a diverse diet and bioavailable sources of micronutrients. In recent years, there has been increased attention to adding micronutrient interventions, on top of the other food-based interventions (such as GFDs and SFPs), to fill micronutrient gaps in diets in emergency settings. The focus of this document is the potential role of LNS in meeting the nutritional needs of these vulnerable subgroups

  2. Applying generalized linear models as an explanatory tool of sex steroids, thyroid hormones and their relationships with environmental and physiologic factors in immature East Pacific green sea turtles (Chelonia mydas).

    PubMed

    Labrada-Martagón, Vanessa; Méndez-Rodríguez, Lia C; Mangel, Marc; Zenteno-Savín, Tania

    2013-09-01

    Generalized linear models were fitted to evaluate the relationship between 17β-estradiol (E2), testosterone (T) and thyroxine (T4) levels in immature East Pacific green sea turtles (Chelonia mydas) and their body condition, size, mass, blood biochemistry parameters, handling time, year, season and site of capture. According to external (tail size) and morphological (<77.3 straight carapace length) characteristics, 95% of the individuals were juveniles. Hormone levels, assessed on sea turtles subjected to a capture stress protocol, were <34.7nmolTL(-1), <532.3pmolE2 L(-1) and <43.8nmolT4L(-1). The statistical model explained biologically plausible metabolic relationships between hormone concentrations and blood biochemistry parameters (e.g. glucose, cholesterol) and the potential effect of environmental variables (season and study site). The variables handling time and year did not contribute significantly to explain hormone levels. Differences in sex steroids between season and study sites found by the models coincided with specific nutritional, physiological and body condition differences related to the specific habitat conditions. The models correctly predicted the median levels of the measured hormones in green sea turtles, which confirms the fitted model's utility. It is suggested that quantitative predictions could be possible when the model is tested with additional data.

  3. Coset spaces for quantum groups

    NASA Astrophysics Data System (ADS)

    Skoda, Zoran

    Consideration of symmetries often simplifies problems in physics and geometry. Quantum groups are analogues of groups, and they can describe a novel kind of symmetry. We view them as objects of noncommutative geometry. They may act on algebras of noncommutative or quantum observables. We propose a theory of coset spaces for quantum groups in the language of coactions of Hopf algebras and analyse an example which should be thought as a quantum group analogue of the flag variety. In the classical case the flag variety is the coset space of the special linear group modulo its Borel subgroup of lower triangular matrices. We introduce and study a notion of localized coinvariants; the quantum group coset space is viewed as a system of algebras of localized coinvariants, equipped with a quantum version of the locally trivial principal bundle where the total space is described by the quantum special linear group and the base space is described by the system of algebras of localized coinvariants. We use quasideterminants, the commutation relations between the quantum minors and the noncommutative Gauss decomposition to formulate and prove the main results. We apply our axiomatization of quantum group fibre bundles to obtain a generalization of a concept of Perelomov coherent states to the Hopf algebra setting and obtain the corresponding resolution of unity formula.

  4. The Additive Impact of Group and Individual Publicly Displayed Feedback: Examining Individual Response Patterns and Response Generalization in a Safe-Driving Occupational Intervention

    ERIC Educational Resources Information Center

    Ludwig, Timothy D.; Geller, E. Scott; Clarke, Steven W.

    2010-01-01

    Additive effects of publicly posting individual feedback following group goal-setting and feedback were evaluated. The turn-signal use of pizza deliverers was studied in a multiple baseline design across two pizza stores. After baseline observations, pizza deliverers voted on a group turn-signal goal and then received 4 weeks of group feedback on…

  5. 26 CFR 1.1502-92A - Ownership change of a loss group or a loss subgroup generally applicable for testing dates before...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... addition to the information concerning stock ownership of the common parent, the single statement must... is an ownership change of a subsidiary. (b) Determination of an ownership change—(1) Parent change method—(i) Loss group. A loss group has an ownership change if the loss group's common parent has...

  6. Comparison of the COPD Population Screener and International Primary Care Airway Group questionnaires in a general Japanese population: the Hisayama study

    PubMed Central

    Tsukuya, Go; Samukawa, Takuya; Matsumoto, Koichiro; Fukuyama, Satoru; Kumamoto, Tomohiro; Uchida, Akifumi; Koriyama, Chihaya; Ninomiya, Toshiharu; Inoue, Hiromasa

    2016-01-01

    Background The incidence of chronic obstructive pulmonary disease (COPD) is increasing worldwide. In Japan and other countries, epidemiological studies have found that many patients with COPD are underdiagnosed and untreated, and thus, early detection and treatment of COPD has been emphasized. Screening questionnaires may have utility in the initial detection of COPD. Objective This study aimed to validate and compare the COPD Population Screener (COPD-PS) and the International Primary Care Airway Group (IPAG) questionnaires in a general Japanese population. Patients and methods Eligible subjects 40 years of age and older living in the town of Hisayama were solicited to participate in a health checkup in 2012. All subjects 40–79 years of age without physician-diagnosed asthma or lung resection were recruited, and 2,336 subjects who fully completed both questionnaires and who had valid spirometry measurements were analyzed. Persistent airflow obstruction (AO) was defined by a postbronchodilator forced expiratory volume in 1 second/forced vital capacity <0.70. Receiver operating characteristic curves, net reclassification improvement, and integrated discrimination improvement were used to examine the ability of the COPD-PS and IPAG questionnaires to discriminate between subjects with and without AO. Results The overall area under the receiver operating characteristic curve for the COPD-PS questionnaire was 0.747 (95% confidence interval [CI], 0.707–0.788) and for the IPAG was 0.775 (95% CI, 0.735–0.816), with no significant difference (P=0.09). The net reclassification improvement and integrated discrimination improvement were −0.107 (95% CI, −0.273–0.058; P=0.203) and −0.014 (95% CI, −0.033–0.006; P=0.182), respectively. Conclusion The five-item COPD-PS questionnaire was comparable to the eight-item IPAG for discriminating between subjects with and without AO. The COPD-PS is a simple and useful screening questionnaire for persistent AO. PMID

  7. Perfect commuting-operator strategies for linear system games

    NASA Astrophysics Data System (ADS)

    Cleve, Richard; Liu, Li; Slofstra, William

    2017-01-01

    Linear system games are a generalization of Mermin's magic square game introduced by Cleve and Mittal. They show that perfect strategies for linear system games in the tensor-product model of entanglement correspond to finite-dimensional operator solutions of a certain set of non-commutative equations. We investigate linear system games in the commuting-operator model of entanglement, where Alice and Bob's measurement operators act on a joint Hilbert space, and Alice's operators must commute with Bob's operators. We show that perfect strategies in this model correspond to possibly infinite-dimensional operator solutions of the non-commutative equations. The proof is based around a finitely presented group associated with the linear system which arises from the non-commutative equations.

  8. The Linear Plasmid Prophage Vp58.5 of Vibrio parahaemolyticus Is Closely Related to the Integrating Phage VHML and Constitutes a New Incompatibility Group of Telomere Phages▿ †

    PubMed Central

    Zabala, Beatriz; Hammerl, Jens A.; Espejo, Romilio T.; Hertwig, Stefan

    2009-01-01

    Vibrio parahaemolyticus O3:K6 pandemic strains recovered in Chile frequently possess a 42-kb plasmid which is the prophage of a myovirus. We studied the prototype phage VP58.5 and show that it does not integrate into the host cell chromosome but replicates as a linear plasmid (Vp58.5) with covalently closed ends (telomeres). The Vp58.5 replicon coexists with other plasmid prophages (N15, PY54, and ΦKO2) in the same cell and thus belongs to a new incompatibility group of telomere phages. We determined the complete nucleotide sequence (42,612 nucleotides) of the VP58.5 phage DNA and compared it with that of the plasmid prophage. The two molecules share the same nucleotide sequence but are 35% circularly permuted to each other. In contrast to the hairpin ends of the plasmid, VP58.5 phage DNA contains 5′-protruding ends. The VP58.5 sequence is 92% identical to the sequence of phage VHML, which was reported to integrate into the host chromosome. However, the gene order and termini of the phage DNAs are different. The VHML genome exhibits the same gene order as does the Vp58.5 plasmid. VHML phage DNA has been reported to contain terminal inverted repeats. This repetitive sequence is similar to the telomere resolution site (telRL) of VP58.5 which, after processing by the phage protelomerase, forms the hairpin ends of the Vp58.5 prophage. It is discussed why these closely related phages may be so different in terms of their genome ends and their lifestyle. PMID:19587034

  9. Identification of Relevant Phytochemical Constituents for Characterization and Authentication of Tomatoes by General Linear Model Linked to Automatic Interaction Detection (GLM-AID) and Artificial Neural Network Models (ANNs)

    PubMed Central

    Hernández Suárez, Marcos; Astray Dopazo, Gonzalo; Larios López, Dina; Espinosa, Francisco

    2015-01-01

    There are a large number of tomato cultivars with a wide range of morphological, chemical, nutritional and sensorial characteristics. Many factors are known to affect the nutrient content of tomato cultivars. A complete understanding of the effect of these factors would require an exhaustive experimental design, multidisciplinary scientific approach and a suitable statistical method. Some multivariate analytical techniques such as Principal Component Analysis (PCA) or Factor Analysis (FA) have been widely applied in order to search for patterns in the behaviour and reduce the dimensionality of a data set by a new set of uncorrelated latent variables. However, in some cases it is not useful to replace the original variables with these latent variables. In this study, Automatic Interaction Detection (AID) algorithm and Artificial Neural Network (ANN) models were applied as alternative to the PCA, AF and other multivariate analytical techniques in order to identify the relevant phytochemical constituents for characterization and authentication of tomatoes. To prove the feasibility of AID algorithm and ANN models to achieve the purpose of this study, both methods were applied on a data set with twenty five chemical parameters analysed on 167 tomato samples from Tenerife (Spain). Each tomato sample was defined by three factors: cultivar, agricultural practice and harvest date. General Linear Model linked to AID (GLM-AID) tree-structured was organized into 3 levels according to the number of factors. p-Coumaric acid was the compound the allowed to distinguish the tomato samples according to the day of harvest. More than one chemical parameter was necessary to distinguish among different agricultural practices and among the tomato cultivars. Several ANN models, with 25 and 10 input variables, for the prediction of cultivar, agricultural practice and harvest date, were developed. Finally, the models with 10 input variables were chosen with fit’s goodness between 44 and

  10. Identification of Relevant Phytochemical Constituents for Characterization and Authentication of Tomatoes by General Linear Model Linked to Automatic Interaction Detection (GLM-AID) and Artificial Neural Network Models (ANNs).

    PubMed

    Hernández Suárez, Marcos; Astray Dopazo, Gonzalo; Larios López, Dina; Espinosa, Francisco

    2015-01-01

    There are a large number of tomato cultivars with a wide range of morphological, chemical, nutritional and sensorial characteristics. Many factors are known to affect the nutrient content of tomato cultivars. A complete understanding of the effect of these factors would require an exhaustive experimental design, multidisciplinary scientific approach and a suitable statistical method. Some multivariate analytical techniques such as Principal Component Analysis (PCA) or Factor Analysis (FA) have been widely applied in order to search for patterns in the behaviour and reduce the dimensionality of a data set by a new set of uncorrelated latent variables. However, in some cases it is not useful to replace the original variables with these latent variables. In this study, Automatic Interaction Detection (AID) algorithm and Artificial Neural Network (ANN) models were applied as alternative to the PCA, AF and other multivariate analytical techniques in order to identify the relevant phytochemical constituents for characterization and authentication of tomatoes. To prove the feasibility of AID algorithm and ANN models to achieve the purpose of this study, both methods were applied on a data set with twenty five chemical parameters analysed on 167 tomato samples from Tenerife (Spain). Each tomato sample was defined by three factors: cultivar, agricultural practice and harvest date. General Linear Model linked to AID (GLM-AID) tree-structured was organized into 3 levels according to the number of factors. p-Coumaric acid was the compound the allowed to distinguish the tomato samples according to the day of harvest. More than one chemical parameter was necessary to distinguish among different agricultural practices and among the tomato cultivars. Several ANN models, with 25 and 10 input variables, for the prediction of cultivar, agricultural practice and harvest date, were developed. Finally, the models with 10 input variables were chosen with fit's goodness between 44 and 100

  11. Placing clinical variables on a common linear scale of empirically based risk as a step towards construction of a general patient acuity score from the electronic health record: a modelling study

    PubMed Central

    Rothman, Steven I; Rothman, Michael J; Solinger, Alan B

    2013-01-01

    Objective To explore the hypothesis that placing clinical variables of differing metrics on a common linear scale of all-cause postdischarge mortality provides risk functions that are directly correlated with in-hospital mortality risk. Design Modelling study. Setting An 805-bed community hospital in the southeastern USA. Participants 42302 inpatients admitted for any reason, excluding obstetrics, paediatric and psychiatric patients. Outcome measures All-cause in-hospital and postdischarge mortalities, and associated correlations. Results Pearson correlation coefficients comparing in-hospital risks with postdischarge risks for creatinine, heart rate and a set of 12 nursing assessments are 0.920, 0.922 and 0.892, respectively. Correlation between postdischarge risk heart rate and the Modified Early Warning System (MEWS) component for heart rate is 0.855. The minimal excess risk values for creatinine and heart rate roughly correspond to the normal reference ranges. We also provide the risks for values outside that range, independent of expert opinion or a regression model. By summing risk functions, a first-approximation patient risk score is created, which correctly ranks 6 discharge categories by average mortality with p<0.001 for differences in category means, and Tukey's Honestly Significant Difference Test confirmed that the means were all different at the 95% confidence level. Conclusions Quantitative or categorical clinical variables can be transformed into risk functions that correlate well with in-hospital risk. This methodology provides an empirical way to assess inpatient risk from data available in the Electronic Health Record. With just the variables in this paper, we achieve a risk score that correlates with discharge disposition. This is the first step towards creation of a universal measure of patient condition that reflects a generally applicable set of health-related risks. More importantly, we believe that our approach opens the door to a way of

  12. Sparse linear programming subprogram

    SciTech Connect

    Hanson, R.J.; Hiebert, K.L.

    1981-12-01

    This report describes a subprogram, SPLP(), for solving linear programming problems. The package of subprogram units comprising SPLP() is written in Fortran 77. The subprogram SPLP() is intended for problems involving at most a few thousand constraints and variables. The subprograms are written to take advantage of sparsity in the constraint matrix. A very general problem statement is accepted by SPLP(). It allows upper, lower, or no bounds on the variables. Both the primal and dual solutions are returned as output parameters. The package has many optional features. Among them is the ability to save partial results and then use them to continue the computation at a later time.

  13. 26 CFR 1.1502-92A - Ownership change of a loss group or a loss subgroup generally applicable for testing dates before...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Under paragraph (b)(1)(i) of this section, section 382 and the regulations thereunder are applied to L...)(1)(i) of this section. The amount of consolidated taxable income of the L loss group for any post... § 1.382-2T nor of the L loss group under paragraph (b)(1)(i) of this section. The following is...

  14. 26 CFR 1.1502-95A - Rules on ceasing to be a member of a consolidated group generally applicable for corporations...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Corporations Joining Or Leaving Consolidated Groups) Before June 25, 1999 § 1.1502-95A Rules on ceasing to be a... portion of the Year 1 consolidated net operating loss, and thereafter each joins with M in filing... join) that is filed after the close of the consolidated return year of the group of which the...

  15. ALPS: A Linear Program Solver

    NASA Technical Reports Server (NTRS)

    Ferencz, Donald C.; Viterna, Larry A.

    1991-01-01

    ALPS is a computer program which can be used to solve general linear program (optimization) problems. ALPS was designed for those who have minimal linear programming (LP) knowledge and features a menu-driven scheme to guide the user through the process of creating and solving LP formulations. Once created, the problems can be edited and stored in standard DOS ASCII files to provide portability to various word processors or even other linear programming packages. Unlike many math-oriented LP solvers, ALPS contains an LP parser that reads through the LP formulation and reports several types of errors to the user. ALPS provides a large amount of solution data which is often useful in problem solving. In addition to pure linear programs, ALPS can solve for integer, mixed integer, and binary type problems. Pure linear programs are solved with the revised simplex method. Integer or mixed integer programs are solved initially with the revised simplex, and the completed using the branch-and-bound technique. Binary programs are solved with the method of implicit enumeration. This manual describes how to use ALPS to create, edit, and solve linear programming problems. Instructions for installing ALPS on a PC compatible computer are included in the appendices along with a general introduction to linear programming. A programmers guide is also included for assistance in modifying and maintaining the program.

  16. Quasideterminant solutions of the generalized Heisenberg magnet model

    NASA Astrophysics Data System (ADS)

    Saleem, U.; Hassan, M.

    2010-01-01

    In this paper we present the Darboux transformation for the generalized Heisenberg magnet (GHM) model based on the general linear Lie group GL(n) and construct multi-soliton solutions in terms of quasideterminants. Further we relate the quasideterminant multi-soliton solutions obtained by means of Darboux transformation with those obtained by the dressing method. We also discuss the model based on the Lie group SU(n) and obtain explicit soliton solutions of the model based on SU(2).

  17. Optimism about safety and group-serving interpretations of safety among pedestrians and cyclists in relation to road use in general and under low light conditions.

    PubMed

    King, M J; Wood, J M; Lacherez, P F; Marszalek, R P

    2012-01-01

    Drivers are known to be optimistic about their risk of crash involvement, believing that they are less likely to be involved in a crash than other drivers. However, little comparative research has been conducted among other road users. In addition, optimism about crash risk is conceptualised as applying only to an individual's assessment of his or her personal risk of crash involvement. The possibility that the self-serving nature of optimism about safety might be generalised to the group-level as a cyclist or a pedestrian, i.e., becoming group-serving rather than self-serving, has been overlooked in relation to road safety. This study analysed a subset of data collected as part of a larger research project on the visibility of pedestrians, cyclists and road workers, focusing on a set of questionnaire items administered to 406 pedestrians, 838 cyclists and 622 drivers. The items related to safety in various scenarios involving drivers, pedestrians and cyclists, allowing predictions to be derived about group differences in agreement with items based on the assumption that the results would exhibit group-serving bias. Analysis of the responses indicated that specific hypotheses about group-serving interpretations of safety and responsibility were supported in 22 of the 26 comparisons. When the nine comparisons relevant to low lighting conditions were considered separately, seven were found to be supported. The findings of the research have implications for public education and for the likely acceptance of messages which are inconsistent with current assumptions and expectations of pedestrians and cyclists. They also suggest that research into group-serving interpretations of safety, even for temporary roles rather than enduring groups, could be fruitful. Further, there is an implication that gains in safety can be made by better educating road users about the limitations of their visibility and the ramifications of this for their own road safety, particularly in low

  18. Doctors and alcohol. The responses of a self-selected group of general practitioners to patients with alcohol-related problems.

    PubMed

    Casswell, S; McPherson, M

    1982-07-14

    A postal survey of New Zealand general practitioners gathered information from a self-selected sample about their response to alcohol problems. Responses to a series of attitude statements measured the extent to which doctors held traditional beliefs about alcoholism as a disease, the management of which requires abstinence; emerging concepts of alcohol dependence and more moralistic attitudes. General practitioners who responded to the survey were found to be largely in sympathy with the disease concept of alcohol problems though some of the more recently emerging concepts were also widely accepted. The majority reported that they felt they did have an active role to play in connection with the alcohol problems of their patients, both in terms of treatment or advice giving, and referral to specialist agencies. Over half of the respondents requested guidelines for treatment and advice giving. Only a small proportion of general practitioners reported pessimism about their personal role in relation to their patients' alcohol problems. The results are discussed in the context of recent research evidence showing the relative efficacy of a structured advice-counseling session of the type in which general practitioners might engage.

  19. OREGANO_VE: a new parallelised 3D solver for the general (non-)linear Maxwell visco-elastic problem: validation and application to the calculation of surface deformation in the earthquake cycle

    NASA Astrophysics Data System (ADS)

    Yamasaki, Tadashi; Houseman, Gregory; Hamling, Ian; Postek, Elek

    2010-05-01

    We have developed a new parallelized 3-D numerical code, OREGANO_VE, for the solution of the general visco-elastic problem in a rectangular block domain. The mechanical equilibrium equation is solved using the finite element method for a (non-)linear Maxwell visco-elastic rheology. Time-dependent displacement and/or traction boundary conditions can be applied. Matrix assembly is based on a tetrahedral element defined by 4 vertex nodes and 6 nodes located at the midpoints of the edges, and within which displacement is described by a quadratic interpolation function. For evaluating viscoelastic relaxation, an explicit time-stepping algorithm (Zienkiewicz and Cormeau, Int. J. Num. Meth. Eng., 8, 821-845, 1974) is employed. We test the accurate implementation of the OREGANO_VE by comparing numerical and analytic (or semi-analytic half-space) solutions to different problems in a range of applications: (1) equilibration of stress in a constant density layer after gravity is switched on at t = 0 tests the implementation of spatially variable viscosity and non-Newtonian viscosity; (2) displacement of the welded interface between two blocks of differing viscosity tests the implementation of viscosity discontinuities, (3) displacement of the upper surface of a layer under applied normal load tests the implementation of time-dependent surface tractions (4) visco-elastic response to dyke intrusion (compared with the solution in a half-space) tests the implementation of all aspects. In each case, the accuracy of the code is validated subject to use of a sufficiently small time step, providing assurance that the OREGANO_VE code can be applied to a range of visco-elastic relaxation processes in three dimensions, including post-seismic deformation and post-glacial uplift. The OREGANO_VE code includes a capability for representation of prescribed fault slip on an internal fault. The surface displacement associated with large earthquakes can be detected by some geodetic observations

  20. A Study of Tracking and Ability Grouping in Mathematics and Science Courses in Virginia's Secondary Schools. House Document No. 58. Report of the Department of Education to the Governor and the General Assembly of Virginia.

    ERIC Educational Resources Information Center

    Virginia State Dept. of Education, Richmond.

    This study was conducted to determine the status of tracking and ability grouping for mathematics and science courses in the public secondary schools of Virginia as required by the General Assembly of Virginia. Guided by Virginia's standards for accrediting public schools that deal with instructional programs, the study team sought to determine if…

  1. A Study of Issues Related to Discipline, Grouping and Tracking, and Special Education in New Castle County, Delaware, Desegration Area. Volume I, General Issues and Introduction: Discipline Study.

    ERIC Educational Resources Information Center

    Achilles, Charles M.; And Others

    In the former New Castle County (Delaware) School District (reorganized into four districts in 1981), minority students were numerically overrepresented from 1979 to 1982 in suspensions from school and in placement in special education and lower academic groupings. To determine if the overrepresentation was based on discriminatory practices or…

  2. 26 CFR 1.1502-95A - Rules on ceasing to be a member of a consolidated group generally applicable for corporations...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Dates (and Corporations Joining Or Leaving Consolidated Groups) Before June 25, 1999 § 1.1502-95A Rules... joins with M in filing consolidated returns. Under § 1.1502-92A, the L loss subgroup has an ownership... the first return in which the members of a new loss subgroup join) that is filed after the close...

  3. 26 CFR 1.1502-95A - Rules on ceasing to be a member of a consolidated group generally applicable for corporations...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Dates (and Corporations Joining Or Leaving Consolidated Groups) Before June 25, 1999 § 1.1502-95A Rules... joins with M in filing consolidated returns. Under § 1.1502-92A, the L loss subgroup has an ownership... the first return in which the members of a new loss subgroup join) that is filed after the close...

  4. 26 CFR 1.1502-95A - Rules on ceasing to be a member of a consolidated group generally applicable for corporations...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Dates (and Corporations Joining Or Leaving Consolidated Groups) Before June 25, 1999 § 1.1502-95A Rules... joins with M in filing consolidated returns. Under § 1.1502-92A, the L loss subgroup has an ownership... the first return in which the members of a new loss subgroup join) that is filed after the close...

  5. 26 CFR 1.1502-95A - Rules on ceasing to be a member of a consolidated group generally applicable for corporations...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Dates (and Corporations Joining Or Leaving Consolidated Groups) Before June 25, 1999 § 1.1502-95A Rules... joins with M in filing consolidated returns. Under § 1.1502-92A, the L loss subgroup has an ownership... the first return in which the members of a new loss subgroup join) that is filed after the close...

  6. 26 CFR 1.1502-91A - Application of section 382 with respect to a consolidated group generally applicable for testing...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... of a group or loss subgroup. (b) Definitions and nomenclature. For purposes of this section and §§ 1.1502-92A through 1.1502-99A, unless otherwise stated: (1) The definitions and nomenclature contained in section 382 and the regulations thereunder (including the nomenclature and assumptions relating to...

  7. 26 CFR 1.1502-91A - Application of section 382 with respect to a consolidated group generally applicable for testing...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... of a group or loss subgroup. (b) Definitions and nomenclature. For purposes of this section and §§ 1.1502-92A through 1.1502-99A, unless otherwise stated: (1) The definitions and nomenclature contained in section 382 and the regulations thereunder (including the nomenclature and assumptions relating to...

  8. General practitioner notes as a source of information for case-control studies in young women. UK National Case-Control Study Group.

    PubMed Central

    Chilvers, C E; Pike, M C; Taylor, C N; Hermon, C; Crossley, B; Smith, S J

    1994-01-01

    STUDY OBJECTIVE--The UK National Case-Control Study was carried out to investigate the relationship between oral contraceptive use and breast cancer risk. This study investigates whether general practitioner notes could be used as the sole data source for epidemiological studies of young women and what the effect would be on non-response and recall bias. DESIGN--Case-control study with data on gynaecological, obstetric, and contraceptive history collected at interview and from general practitioners' notes. Information from these two sources was compared. SETTING--This was a population-based study. PARTICIPANTS--Altogether 755 women with breast cancer aged under 36 years at diagnosis, each with an age-matched control, participated in the study. Response rates at interview were 72% and 89% for cases and controls but GP data were available for 90% of the 1049 case and first-selected control pairs. MAIN RESULTS--There was generally good agreement between the two data sources with respect to obstetric history and gynaecological procedures (hysterectomy, oophorectomy, and tubal ligation). The use of intra-uterine devices, or diaphragm, and partner's vasectomy were not reliably recorded in the GP's notes. The overall results of the UK study would have been qualitatively the same with respect to the relationship between oral contraceptive use and breast cancer risk if GP notes only had been used, in spite of the fact that only about half of all oral contraceptive usage was recorded in the notes. Response rates would have been higher, recall bias eliminated, and the cost of the study halved. CONCLUSIONS--When planning case-control studies in young women, the possibility of using GP notes as the primary data source should be considered. Lack of data on potential confounding factors is a possible drawback to such use. The practice of destroying GP's notes shortly after the death of patients seriously restricts the possibility of using these notes when studying rapidly fatal

  9. Quadratic Generalized Scale Invariance

    NASA Astrophysics Data System (ADS)

    Lovejoy, S.; Schertzer, D.; Addor, J. B.

    Nearly twenty years ago, two of us argued that in order to account for the scaling strat- ification of the atmosphere, that an anisotropic "unified scaling model" of the atmo- sphere was required with elliptical dimension 23/9=2.555... "in between" the standard 3-D (small scale) and 2-D large scale model. This model was based on the formal- ism of generalized scale invariance (GSI). Physically, GSI is justified by arguing that various conserved fluxes (energy, buoyancy force variance etc.) should define the ap- propriate notion of scale. In a recent large scale satellite cloud image analysis, we directly confirmed this model by studying the isotropic (angle averaged) horizontal cloud statistics. Mathematically, GSI is based on a a group of scale changing opera- tors and their generators but to date, both analyses (primarily of cloud images) and nu- merical (multifractal) simulations, have been limited to the special case of linear GSI. This has shown that cloud texture can plausibly be associated with local linearizations. However realistic morphologies involve spatially avarying textures; the full non linear GSI is clearly necessary. In this talk, we first show that the observed angle averaged (multi)scaling statistics only give a realtively weak constraint on the nonlinear gner- ator: that the latter can be expressed by self-similar (isotropic) part, and a deviatoric part described (in two dimensions) by an arbitrary scalar potential which contains all the information about the cloud morphology. We then show (using a theorem due to Poincaré) how to reduce nonlinear GSI to linear GSI plus a nonlinear coordinate trans- formation numerically, using this to take multifractal GSI modelling to the next level of approximation: quadratic GSI. We show many examples of the coresponding simu- lations which include transitions from various morphologies (including cyclones) and we discuss the results in relation to satellite cloud images.

  10. Utilizing the Zero-One Linear Programming Constraints to Draw Multiple Sets of Matched Samples from a Non-Treatment Population as Control Groups for the Quasi-Experimental Design

    ERIC Educational Resources Information Center

    Li, Yuan H.; Yang, Yu N.; Tompkins, Leroy J.; Modarresi, Shahpar

    2005-01-01

    The statistical technique, "Zero-One Linear Programming," that has successfully been used to create multiple tests with similar characteristics (e.g., item difficulties, test information and test specifications) in the area of educational measurement, was deemed to be a suitable method for creating multiple sets of matched samples to be…

  11. [Environmental and biological monitoring of exposure to PAHs in Taranto coke-oven workers and in two groups of the general population from Apulia].

    PubMed

    Campo, L; Vimercati, L; Carrus, A; Bisceglia, L; Pesatori, A C; Bertazzi, P A; Assennato, G; Fustinoni, S

    2012-01-01

    The exposure to PAHs was assessed by personal air sampling and urinary 1-hydroxypyrene (1-OHP) in 100 coke-oven workers (CW) of the Taranto plant and in subjects from the general population living close (NC, 18) and far away (FC, 15) from the plant. Median airborne benzo[a]pyrene (BaP) and 1-OHP levels were 152, 1.5, and 3.6 ng/m3 and 2.0, 0.5 and 0.6 microg/g creatinine in CW, NC, and FC, respectively. BaP exposure exceeded the German acceptable (70 ng/m3) and tolerable (700 ng/m3) limit risk based values in 82 and 11% of CW and the European target value for ambient air (1 ng/m3) in about 65% of NC and FC. 1-OHP levels exceed the proposed biological limit value for the coke-oven industry (4.4 microg/g crt) in 21% of CW and the Italian reference value (0.3 microg/g crt) in about 90% of NC and FC. The exposure resulted lower than in the past, but this study highlights that PAHs exposure from the coke plant still poses a health risk for workers and the general population.

  12. Generalized SU(2) Proca theory

    NASA Astrophysics Data System (ADS)

    Allys, Erwan; Peter, Patrick; Rodríguez, Yeinzon

    2016-10-01

    Following previous works on generalized Abelian Proca theory, also called vector Galileon, we investigate the massive extension of an SU(2) gauge theory, i.e., the generalized SU(2) Proca model, which could be dubbed non-Abelian vector Galileon. This particular symmetry group permits fruitful applications in cosmology such as inflation driven by gauge fields. Our approach consists in building, in an exhaustive way, all the Lagrangians containing up to six contracted Lorentz indices. For this purpose, and after identifying by group theoretical considerations all the independent Lagrangians which can be written at these orders, we consider the only linear combinations propagating 3 degrees of freedom and having healthy dynamics for their longitudinal mode, i.e., whose pure Stückelberg contribution turns into the SU(2) multi-Galileon dynamics. Finally, and after having considered the curved space-time expansion of these Lagrangians, we discuss the form of the theory at all subsequent orders.

  13. Generalized Multilevel Structural Equation Modeling

    ERIC Educational Resources Information Center

    Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew

    2004-01-01

    A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…

  14. MS overline -on-shell quark mass relation up to four loops in QCD and a general SU (N ) gauge group

    NASA Astrophysics Data System (ADS)

    Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias; Wellmann, David

    2016-10-01

    We compute the relation between heavy quark masses defined in the modified minimal subtraction and the on-shell schemes. Detailed results are presented for all coefficients of the SU (Nc) color factors. The reduction of the four-loop on-shell integrals is performed for a general QCD gauge parameter. Altogether there are about 380 master integrals. Some of them are computed analytically, others with high numerical precision using Mellin-Barnes representations, and the rest numerically with the help of FIESTA. We discuss in detail the precise numerical evaluation of the four-loop master integrals. Updated relations between various short-distance masses and the MS ¯ quark mass to next-to-next-to-next-to-leading order accuracy are provided for the charm, bottom and top quarks. We discuss the dependence on the renormalization and factorization scale.

  15. Linearly Forced Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Lundgren, T. S.

    2003-01-01

    Stationary isotropic turbulence is often studied numerically by adding a forcing term to the Navier-Stokes equation. This is usually done for the purpose of achieving higher Reynolds number and longer statistics than is possible for isotropic decaying turbulence. It is generally accepted that forcing the Navier-Stokes equation at low wave number does not influence the small scale statistics of the flow provided that there is wide separation between the largest and smallest scales. It will be shown, however, that the spectral width of the forcing has a noticeable effect on inertial range statistics. A case will be made here for using a broader form of forcing in order to compare computed isotropic stationary turbulence with (decaying) grid turbulence. It is shown that using a forcing function which is directly proportional to the velocity has physical meaning and gives results which are closer to both homogeneous and non-homogeneous turbulence. Section 1 presents a four part series of motivations for linear forcing. Section 2 puts linear forcing to a numerical test with a pseudospectral computation.

  16. Non Linear Conjugate Gradient

    SciTech Connect

    Newman, Gregory A.; Commer, Michael

    2006-11-17

    Software that simulates and inverts electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a time harmonic source field excitation arising from the following antenna geometery: loops and grounded bipoles, as well as point electric and magnetic dioples. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria. The software is an upgrade from the code NLCGCS_MP ver 1.0. The upgrade includes the following components: Incorporation of new 1 D field sourcing routines to more accurately simulate the 3D electromagnetic field for arbitrary geologic& media, treatment for generalized finite length transmitting antenna geometry (antennas with vertical and horizontal component directions). In addition, the software has been upgraded to treat transverse anisotropy in electrical conductivity.

  17. Standard Error of Linear Observed-Score Equating for the NEAT Design with Nonnormally Distributed Data

    ERIC Educational Resources Information Center

    Zu, Jiyun; Yuan, Ke-Hai

    2012-01-01

    In the nonequivalent groups with anchor test (NEAT) design, the standard error of linear observed-score equating is commonly estimated by an estimator derived assuming multivariate normality. However, real data are seldom normally distributed, causing this normal estimator to be inconsistent. A general estimator, which does not rely on the…

  18. Why quantum dynamics is linear

    NASA Astrophysics Data System (ADS)

    Jordan, Thomas F.

    2009-11-01

    A seed George planted 45 years ago is still producing fruit now. In 1961, George set out the fundamental proposition that quantum dynamics is described most generally by linear maps of density matrices. Since the first sprout from George's seed appeared in 1962, we have known that George's fundamental proposition can be used to derive the linear Schrodinger equation in cases where it can be expected to apply. Now we have a proof of George's proposition that density matrices are mapped linearly to density matrices, that there can be no nonlinear generalization of this. That completes the derivation of the linear Schrodinger equation. The proof of George's proposition replaces Wigner's theorem that a symmetry transformation is represented by a linear or antilinear operator. The assumption needed to prove George's proposition is just that the dynamics does not depend on anything outside the system but must allow the system to be described as part of a larger system. This replaces the physically less compelling assumption of Wigner's theorem that absolute values of inner products are preserved. The history of this question is reviewed. Nonlinear generalizations of quantum mechanics have been proposed. They predict small but clear nonlinear effects, which very accurate experiments have not seen. This begs the question. Is there a reason in principle why nonlinearity is not found? Is it impossible? Does quantum dynamics have to be linear? Attempts to prove this have not been decisive, because either their assumptions are not compelling or their arguments are not conclusive. The question has been left unsettled. The simple answer, based on a simple assumption, was found in two steps separated by 44 years.

  19. Preconditioned quantum linear system algorithm.

    PubMed

    Clader, B D; Jacobs, B C; Sprouse, C R

    2013-06-21

    We describe a quantum algorithm that generalizes the quantum linear system algorithm [Harrow et al., Phys. Rev. Lett. 103, 150502 (2009)] to arbitrary problem specifications. We develop a state preparation routine that can initialize generic states, show how simple ancilla measurements can be used to calculate many quantities of interest, and integrate a quantum-compatible preconditioner that greatly expands the number of problems that can achieve exponential speedup over classical linear systems solvers. To demonstrate the algorithm's applicability, we show how it can be used to compute the electromagnetic scattering cross section of an arbitrary target exponentially faster than the best classical algorithm.

  20. The Panchromatic High-Resolution Spectroscopic Survey of Local Group Star Clusters. I. General data reduction procedures for the VLT/X-shooter UVB and VIS arm

    NASA Astrophysics Data System (ADS)

    Schönebeck, Frederik; Puzia, Thomas H.; Pasquali, Anna; Grebel, Eva K.; Kissler-Patig, Markus; Kuntschner, Harald; Lyubenova, Mariya; Perina, Sibilla

    2014-12-01

    Aims: Our dataset contains spectroscopic observations of 29 globular clusters in the Magellanic Clouds and the Milky Way performed with VLT/X-shooter over eight full nights. To derive robust results instrument and pipeline systematics have to be well understood and properly modeled. We aim at a consistent data reduction procedure with an accurate understanding of the measurement accuracy limitations. Here we present detailed data reduction procedures for the VLT/X-shooter UVB and VIS arm. These are not restricted to our particular dataset, but are generally applicable to different kinds of X-shooter data without major limitation on the astronomical object of interest. Methods: ESO's X-shooter pipeline (v1.5.0) performs well and reliably for the wavelength calibration and the associated rectification procedure, yet we find several weaknesses in the reduction cascade that are addressed with additional calibration steps, such as bad pixel interpolation, flat fielding, and slit illumination corrections. Furthermore, the instrumental PSF is analytically modeled and used to reconstruct flux losses at slit transit. This also forms the basis for an optimal extraction of point sources out of the two-dimensional pipeline product. Regular observations of spectrophotometric standard stars obtained from the X-shooter archive allow us to detect instrumental variability, which needs to be understood if a reliable absolute flux calibration is desired. Results: A cascade of additional custom calibration steps is presented that allows for an absolute flux calibration uncertainty of ≲10% under virtually every observational setup, provided that the signal-to-noise ratio is sufficiently high. The optimal extraction increases the signal-to-noise ratio typically by a factor of 1.5, while simultaneously correcting for resulting flux losses. The wavelength calibration is found to be accurate to an uncertainty level of Δλ ≃ 0.02 Å. Conclusions: We find that most of the X

  1. A general route to monoorganopnicogen(III) (M = Sb, Bi) compounds with a pincer (N,C,N) group and oxo ligands.

    PubMed

    Strîmb, Gabriela; Pöllnitz, Alpár; Raţ, Ciprian I; Silvestru, Cristian

    2015-06-07

    The reaction of RMCl2 [R = 2,6-[MeN(CH2CH2)2NCH2]2C6H3; M = Sb (1), Bi (2)] with KOH affords the isolation of the oxides cyclo-R2M2O2 [M = Sb (3), Bi (4)]. Treatment of 3 with trifluoroacetic acid produced an ionic species (5) with a dinuclear cation that contains organic ligands protonated partially at one of the pendant arms. The cyclic oxides 3 and 4 are able to trap gaseous CO2 to give “RMCO3” [M = Sb (6), Bi (7)], the degree of these organometallic carbonates’ oligomerization being under investigation. The reactivity of the dinuclear oxide 3 was also investigated towards oxalic acid or dopamine hydrochloride and pure mononuclear compounds could be isolated, i.e. RSb[O(O)CC(O)O] (8) and RSb[O2-1,2-C6H3-3-(CH2)2NH3]Cl (9). The reaction of the dichlorides 1 and 2 with ethylene glycol, pinacol or catechol, in the presence of KOH, led to 2-organo-1,3,2-dioxastibolanes or -bismolanes RM(OCH2)2 [M = Sb (10), Bi (11)], RM(OCMe2)2 [M = Sb (12), Bi (13)] and 2-organo-1,3,2-dioxastibole or -bismole RM(O2-1,2-C6H4) [M = Sb (14), Bi (15)], respectively. The compounds were investigated by NMR spectroscopy, including variable temperature experiments, providing evidence for the presence of the intramolecular N→M interactions in solution. Single crystal X-ray diffraction studies were performed for most compounds and revealed an organic group R acting as a pincer ligand resulting in a distorted square pyramidal (N,C,N)MO2 core with cis intramolecular N→M interactions placed trans to M–O bonds. This is in contrast to the N→M interactions trans to each other as found in the RMCl2 used as starting materials. The crystals of the oxides 3 and 4·4H2O contain different geometric isomers with anti and syn orientation of the M–C bonds, respectively, with respect to the planar M2O2 ring. In the supramolecular polymeric architecture established in the crystal of 4·4H2O an important finding is the experimental observation of water hexamer units with a [tetramer + 2

  2. Minimal Solution of Singular LR Fuzzy Linear Systems

    PubMed Central

    Nikuie, M.; Ahmad, M. Z.

    2014-01-01

    In this paper, the singular LR fuzzy linear system is introduced. Such systems are divided into two parts: singular consistent LR fuzzy linear systems and singular inconsistent LR fuzzy linear systems. The capability of the generalized inverses such as Drazin inverse, pseudoinverse, and {1}-inverse in finding minimal solution of singular consistent LR fuzzy linear systems is investigated. PMID:24737977

  3. Linear Logistic Test Modeling with R

    ERIC Educational Resources Information Center

    Baghaei, Purya; Kubinger, Klaus D.

    2015-01-01

    The present paper gives a general introduction to the linear logistic test model (Fischer, 1973), an extension of the Rasch model with linear constraints on item parameters, along with eRm (an R package to estimate different types of Rasch models; Mair, Hatzinger, & Mair, 2014) functions to estimate the model and interpret its parameters. The…

  4. Linear determining equations for differential constraints

    SciTech Connect

    Kaptsov, O V

    1998-12-31

    A construction of differential constraints compatible with partial differential equations is considered. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the classical determining equations used in the search for admissible Lie operators. As applications of this approach equations of an ideal incompressible fluid and non-linear heat equations are discussed.

  5. A Constrained Linear Estimator for Multiple Regression

    ERIC Educational Resources Information Center

    Davis-Stober, Clintin P.; Dana, Jason; Budescu, David V.

    2010-01-01

    "Improper linear models" (see Dawes, Am. Psychol. 34:571-582, "1979"), such as equal weighting, have garnered interest as alternatives to standard regression models. We analyze the general circumstances under which these models perform well by recasting a class of "improper" linear models as "proper" statistical models with a single predictor. We…

  6. A neural network for bounded linear programming

    SciTech Connect

    Culioli, J.C.; Protopopescu, V.; Britton, C.; Ericson, N. )

    1989-01-01

    The purpose of this paper is to describe a neural network implementation of an algorithm recently designed at ORNL to solve the Transportation and the Assignment Problems, and, more generally, any explicitly bounded linear program. 9 refs.

  7. Group Dynamic Processes in Email Groups

    ERIC Educational Resources Information Center

    Alpay, Esat

    2005-01-01

    Discussion is given on the relevance of group dynamic processes in promoting decision-making in email discussion groups. General theories on social facilitation and social loafing are considered in the context of email groups, as well as the applicability of psychodynamic and interaction-based models. It is argued that such theories may indeed…

  8. GENERAL PURPOSE ADA PACKAGES

    NASA Technical Reports Server (NTRS)

    Klumpp, A. R.

    1994-01-01

    Ten families of subprograms are bundled together for the General-Purpose Ada Packages. The families bring to Ada many features from HAL/S, PL/I, FORTRAN, and other languages. These families are: string subprograms (INDEX, TRIM, LOAD, etc.); scalar subprograms (MAX, MIN, REM, etc.); array subprograms (MAX, MIN, PROD, SUM, GET, and PUT); numerical subprograms (EXP, CUBIC, etc.); service subprograms (DATE_TIME function, etc.); Linear Algebra II; Runge-Kutta integrators; and three text I/O families of packages. In two cases, a family consists of a single non-generic package. In all other cases, a family comprises a generic package and its instances for a selected group of scalar types. All generic packages are designed to be easily instantiated for the types declared in the user facility. The linear algebra package is LINRAG2. This package includes subprograms supplementing those in NPO-17985, An Ada Linear Algebra Package Modeled After HAL/S (LINRAG). Please note that LINRAG2 cannot be compiled without LINRAG. Most packages have widespread applicability, although some are oriented for avionics applications. All are designed to facilitate writing new software in Ada. Several of the packages use conventions introduced by other programming languages. A package of string subprograms is based on HAL/S (a language designed for the avionics software in the Space Shuttle) and PL/I. Packages of scalar and array subprograms are taken from HAL/S or generalized current Ada subprograms. A package of Runge-Kutta integrators is patterned after a built-in MAC (MIT Algebraic Compiler) integrator. Those packages modeled after HAL/S make it easy to translate existing HAL/S software to Ada. The General-Purpose Ada Packages program source code is available on two 360K 5.25" MS-DOS format diskettes. The software was developed using VAX Ada v1.5 under DEC VMS v4.5. It should be portable to any validated Ada compiler and it should execute either interactively or in batch. The largest package

  9. Linear integrated circuits

    NASA Astrophysics Data System (ADS)

    Young, T.

    This book is intended to be used as a textbook in a one-semester course at a variety of levels. Because of self-study features incorporated, it may also be used by practicing electronic engineers as a formal and thorough introduction to the subject. The distinction between linear and digital integrated circuits is discussed, taking into account digital and linear signal characteristics, linear and digital integrated circuit characteristics, the definitions for linear and digital circuits, applications of digital and linear integrated circuits, aspects of fabrication, packaging, and classification and numbering. Operational amplifiers are considered along with linear integrated circuit (LIC) power requirements and power supplies, voltage and current regulators, linear amplifiers, linear integrated circuit oscillators, wave-shaping circuits, active filters, DA and AD converters, demodulators, comparators, instrument amplifiers, current difference amplifiers, analog circuits and devices, and aspects of troubleshooting.

  10. A linear programming manual

    NASA Technical Reports Server (NTRS)

    Tuey, R. C.

    1972-01-01

    Computer solutions of linear programming problems are outlined. Information covers vector spaces, convex sets, and matrix algebra elements for solving simultaneous linear equations. Dual problems, reduced cost analysis, ranges, and error analysis are illustrated.

  11. Linear Accelerator (LINAC)

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? A linear accelerator (LINAC) is the ... Therapy (SBRT) . top of page How does the equipment work? The linear accelerator uses microwave technology (similar ...

  12. Factors that influence self-reported general health status among different Asian ethnic groups: evidence from the Roadmap to the New Horizon: Linking Asians to Improved Health and Wellness study.

    PubMed

    Maty, Siobhan C; Leung, Holden; Lau, Christine; Kim, Gemma

    2011-06-01

    Little is known about the determinants of self-reported general health status among different Asian ethnic subgroups. Using a community-based participatory research approach, we designed, administered, and analyzed a cross-sectional survey of 705 Asians (292 Chinese, 226 Korean, 187 Vietnamese) in the Portland, Oregon region to describe associations between general health status and several sociodemographic and health-related factors in pooled and ethnic-group-stratified samples. Ethnic variation existed in all covariate distributions, except employment, public-service use, language use, health status, visiting healthcare providers, sleep habits, and use of prayer, meditation, yoga or acupuncture. Acculturation measures were strong predictors of poor/fair health in logistic regression models regardless of ethnicity. Ethnic variation in outcome status existed for all remaining covariates. Most health-related research overlooks the heterogeneity within the Asian population. These findings highlight substantial variability in the associations between self-reported general health status and sociodemographic and health-related measures between Asian ethnic groups.

  13. Order-constrained linear optimization.

    PubMed

    Tidwell, Joe W; Dougherty, Michael R; Chrabaszcz, Jeffrey S; Thomas, Rick P

    2017-02-27

    Despite the fact that data and theories in the social, behavioural, and health sciences are often represented on an ordinal scale, there has been relatively little emphasis on modelling ordinal properties. The most common analytic framework used in psychological science is the general linear model, whose variants include ANOVA, MANOVA, and ordinary linear regression. While these methods are designed to provide the best fit to the metric properties of the data, they are not designed to maximally model ordinal properties. In this paper, we develop an order-constrained linear least-squares (OCLO) optimization algorithm that maximizes the linear least-squares fit to the data conditional on maximizing the ordinal fit based on Kendall's τ. The algorithm builds on the maximum rank correlation estimator (Han, 1987, Journal of Econometrics, 35, 303) and the general monotone model (Dougherty & Thomas, 2012, Psychological Review, 119, 321). Analyses of simulated data indicate that when modelling data that adhere to the assumptions of ordinary least squares, OCLO shows minimal bias, little increase in variance, and almost no loss in out-of-sample predictive accuracy. In contrast, under conditions in which data include a small number of extreme scores (fat-tailed distributions), OCLO shows less bias and variance, and substantially better out-of-sample predictive accuracy, even when the outliers are removed. We show that the advantages of OCLO over ordinary least squares in predicting new observations hold across a variety of scenarios in which researchers must decide to retain or eliminate extreme scores when fitting data.

  14. IR Linearity Monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2012-10-01

    These observations will be used to monitor the signal non-linearity of the IR channel, as well as to update the IR channel non-linearity calibration reference file. The non-linearity behavior of each pixel in the detector will be investigated through the use of full frame and subarray flat fields, while the photometric behavior of point sources will be studied using observations of 47 Tuc. This is a continuation of the Cycle 19 non-linearity monitor, program 12696.

  15. IR linearity monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2013-10-01

    These observations will be used to monitor the signal non-linearity of the IR channel, as well as to update the IR channel non-linearity calibration reference file. The non-linearity behavior of each pixel in the detector will be investigated through the use of full frame and subarray flat fields, while the photometric behavior of point sources will be studied using observations of 47 Tuc. This is a continuation of the Cycle 20 non-linearity monitor, program 13079.

  16. Linear-Algebra Programs

    NASA Technical Reports Server (NTRS)

    Lawson, C. L.; Krogh, F. T.; Gold, S. S.; Kincaid, D. R.; Sullivan, J.; Williams, E.; Hanson, R. J.; Haskell, K.; Dongarra, J.; Moler, C. B.

    1982-01-01

    The Basic Linear Algebra Subprograms (BLAS) library is a collection of 38 FORTRAN-callable routines for performing basic operations of numerical linear algebra. BLAS library is portable and efficient source of basic operations for designers of programs involving linear algebriac computations. BLAS library is supplied in portable FORTRAN and Assembler code versions for IBM 370, UNIVAC 1100 and CDC 6000 series computers.

  17. Invertible linear ordinary differential operators

    NASA Astrophysics Data System (ADS)

    Chetverikov, Vladimir N.

    2017-03-01

    We consider invertible linear ordinary differential operators whose inversions are also differential operators. To each such operator we assign a numerical table. These tables are described in the elementary geometrical language. The table does not uniquely determine the operator. To define this operator uniquely some additional information should be added, as it is described in detail in this paper. The possibility of generalization of these results to partial differential operators is also discussed.

  18. LINPACK. Simultaneous Linear Algebraic Equations

    SciTech Connect

    Miller, M.A.

    1990-05-01

    LINPACK is a collection of FORTRAN subroutines which analyze and solve various classes of systems of simultaneous linear algebraic equations. The collection deals with general, banded, symmetric indefinite, symmetric positive definite, triangular, and tridiagonal square matrices, as well as with least squares problems and the QR and singular value decompositions of rectangular matrices. A subroutine-naming convention is employed in which each subroutine name consists of five letters which represent a coded specification (TXXYY) of the computation done by that subroutine. The first letter, T, indicates the matrix data type. Standard FORTRAN allows the use of three such types: S REAL, D DOUBLE PRECISION, and C COMPLEX. In addition, some FORTRAN systems allow a double-precision complex type: Z COMPLEX*16. The second and third letters of the subroutine name, XX, indicate the form of the matrix or its decomposition: GE General, GB General band, PO Positive definite, PP Positive definite packed, PB Positive definite band, SI Symmetric indefinite, SP Symmetric indefinite packed, HI Hermitian indefinite, HP Hermitian indefinite packed, TR Triangular, GT General tridiagonal, PT Positive definite tridiagonal, CH Cholesky decomposition, QR Orthogonal-triangular decomposition, SV Singular value decomposition. The final two letters, YY, indicate the computation done by the particular subroutine: FA Factor, CO Factor and estimate condition, SL Solve, DI Determinant and/or inverse and/or inertia, DC Decompose, UD Update, DD Downdate, EX Exchange. The LINPACK package also includes a set of routines to perform basic vector operations called the Basic Linear Algebra Subprograms (BLAS).

  19. LINPACK. Simultaneous Linear Algebraic Equations

    SciTech Connect

    Dongarra, J.J.

    1982-05-02

    LINPACK is a collection of FORTRAN subroutines which analyze and solve various classes of systems of simultaneous linear algebraic equations. The collection deals with general, banded, symmetric indefinite, symmetric positive definite, triangular, and tridiagonal square matrices, as well as with least squares problems and the QR and singular value decompositions of rectangular matrices. A subroutine-naming convention is employed in which each subroutine name consists of five letters which represent a coded specification (TXXYY) of the computation done by that subroutine. The first letter, T, indicates the matrix data type. Standard FORTRAN allows the use of three such types: S REAL, D DOUBLE PRECISION, and C COMPLEX. In addition, some FORTRAN systems allow a double-precision complex type: Z COMPLEX*16. The second and third letters of the subroutine name, XX, indicate the form of the matrix or its decomposition: GE General, GB General band, PO Positive definite, PP Positive definite packed, PB Positive definite band, SI Symmetric indefinite, SP Symmetric indefinite packed, HI Hermitian indefinite, HP Hermitian indefinite packed, TR Triangular, GT General tridiagonal, PT Positive definite tridiagonal, CH Cholesky decomposition, QR Orthogonal-triangular decomposition, SV Singular value decomposition. The final two letters, YY, indicate the computation done by the particular subroutine: FA Factor, CO Factor and estimate condition, SL Solve, DI Determinant and/or inverse and/or inertia, DC Decompose, UD Update, DD Downdate, EX Exchange. The LINPACK package also includes a set of routines to perform basic vector operations called the Basic Linear Algebra Subprograms (BLAS).

  20. Linear collider: a preview

    SciTech Connect

    Wiedemann, H.

    1981-11-01

    Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.

  1. The linear separability problem: some testing methods.

    PubMed

    Elizondo, D

    2006-03-01

    The notion of linear separability is used widely in machine learning research. Learning algorithms that use this concept to learn include neural networks (single layer perceptron and recursive deterministic perceptron), and kernel machines (support vector machines). This paper presents an overview of several of the methods for testing linear separability between two classes. The methods are divided into four groups: Those based on linear programming, those based on computational geometry, one based on neural networks, and one based on quadratic programming. The Fisher linear discriminant method is also presented. A section on the quantification of the complexity of classification problems is included.

  2. Linear mass actuator

    NASA Technical Reports Server (NTRS)

    Holloway, Sidney E., III (Inventor); Crossley, Edward A., Jr. (Inventor); Jones, Irby W. (Inventor); Miller, James B. (Inventor); Davis, C. Calvin (Inventor); Behun, Vaughn D. (Inventor); Goodrich, Lewis R., Sr. (Inventor)

    1992-01-01

    A linear mass actuator includes an upper housing and a lower housing connectable to each other and having a central passageway passing axially through a mass that is linearly movable in the central passageway. Rollers mounted in the upper and lower housings in frictional engagement with the mass translate the mass linearly in the central passageway and drive motors operatively coupled to the roller means, for rotating the rollers and driving the mass axially in the central passageway.

  3. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  4. Linear phase compressive filter

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

  5. Linear phase compressive filter

    DOEpatents

    McEwan, T.E.

    1995-06-06

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line. 2 figs.

  6. Recombineering linear BACs.

    PubMed

    Chen, Qingwen; Narayanan, Kumaran

    2015-01-01

    Recombineering is a powerful genetic engineering technique based on homologous recombination that can be used to accurately modify DNA independent of its sequence or size. One novel application of recombineering is the assembly of linear BACs in E. coli that can replicate autonomously as linear plasmids. A circular BAC is inserted with a short telomeric sequence from phage N15, which is subsequently cut and rejoined by the phage protelomerase enzyme to generate a linear BAC with terminal hairpin telomeres. Telomere-capped linear BACs are protected against exonuclease attack both in vitro and in vivo in E. coli cells and can replicate stably. Here we describe step-by-step protocols to linearize any BAC clone by recombineering, including inserting and screening for presence of the N15 telomeric sequence, linearizing BACs in vivo in E. coli, extracting linear BACs, and verifying the presence of hairpin telomere structures. Linear BACs may be useful for functional expression of genomic loci in cells, maintenance of linear viral genomes in their natural conformation, and for constructing innovative artificial chromosome structures for applications in mammalian and plant cells.

  7. A cluster-randomised, parallel group, controlled intervention study of genetic prostate cancer risk assessment and use of PSA tests in general practice—the ProCaRis study: study protocol

    PubMed Central

    Kirkegaard, Pia; Vedsted, Peter; Edwards, Adrian; Fenger-Grøn, Morten; Bro, Flemming

    2013-01-01

    Introduction Unsystematic screening for prostate cancer (PCa) is common, causing a high number of false-positive results. Valid instruments for assessment of individual risk of PCa have been called for. A DNA-based genetic test has been tested retrospectively. The clinical use of this test needs further investigation. The primary objective is to evaluate the impact on the use of prostate-specific antigen (PSA) tests of introducing genetic PCa risk assessment in general practice. The secondary objectives are to evaluate PCa-related patient experiences, and to explore sociocultural aspects of genetic risk assessment in patients at high PCa risk. Methods and analysis The study is a cluster-randomised, controlled intervention study with practice as the unit of randomisation. We expect 140 practices to accept participation and include a total of 1244 patients in 4 months. Patients requesting a PSA test in the intervention group practices will be offered a genetic PCa risk assessment. Patients requesting a PSA test in the control group practices will be handled according to current guidelines. Data will be collected from registers, patient questionnaires and interviews. Quantitative data will be analysed according to intention-to-treat principles. Baseline characteristics will be compared between groups. Longitudinal analyses will include time in risk, and multivariable analysis will be conducted to evaluate the influence of general practitioner and patient-specific variables on future PSA testing. Interview data will be transcribed verbatim and analysed from a social-constructivist perspective. Ethics and dissemination Consent will be obtained from patients who can withdraw from the study at any time. The study provides data to the ongoing conceptual and ethical discussions about genetic risk assessment and classification of low-risk and high-risk individuals. The intervention model might be applicable to other screening areas regarding risk of cancer with identified

  8. Similarity analysis of differential equations by Lie group.

    NASA Technical Reports Server (NTRS)

    Na, T. Y.; Hansen, A. G.

    1971-01-01

    Methods for transforming partial differential equations into forms more suitable for analysis and solution are investigated. The idea of Lie's infinitesimal contact transformation group is introduced to develop a systematic method which involves mostly algebraic manipulations. A thorough presentation of the application of this general method to the problem of similarity analysis in a broader sense - namely, the similarity between partial and ordinary differential equations, boundary value and initial value problems, and nonlinear and linear equations - is given with new and very general methods evolved for deriving the possible groups of transformations.

  9. Systems of Inhomogeneous Linear Equations

    NASA Astrophysics Data System (ADS)

    Scherer, Philipp O. J.

    Many problems in physics and especially computational physics involve systems of linear equations which arise e.g. from linearization of a general nonlinear problem or from discretization of differential equations. If the dimension of the system is not too large standard methods like Gaussian elimination or QR decomposition are sufficient. Systems with a tridiagonal matrix are important for cubic spline interpolation and numerical second derivatives. They can be solved very efficiently with a specialized Gaussian elimination method. Practical applications often involve very large dimensions and require iterative methods. Convergence of Jacobi and Gauss-Seidel methods is slow and can be improved by relaxation or over-relaxation. An alternative for large systems is the method of conjugate gradients.

  10. SLAC Linear Collider

    SciTech Connect

    Richter, B.

    1985-12-01

    A report is given on the goals and progress of the SLAC Linear Collider. The status of the machine and the detectors are discussed and an overview is given of the physics which can be done at this new facility. Some ideas on how (and why) large linear colliders of the future should be built are given.

  11. Linear Equations: Equivalence = Success

    ERIC Educational Resources Information Center

    Baratta, Wendy

    2011-01-01

    The ability to solve linear equations sets students up for success in many areas of mathematics and other disciplines requiring formula manipulations. There are many reasons why solving linear equations is a challenging skill for students to master. One major barrier for students is the inability to interpret the equals sign as anything other than…

  12. Linearization of Robot Manipulators

    NASA Technical Reports Server (NTRS)

    Kreutz, Kenneth

    1987-01-01

    Four nonlinear control schemes equivalent. Report discusses theory of nonlinear feedback control of robot manipulator, emphasis on control schemes making manipulator input and output behave like decoupled linear system. Approach, called "exact external linearization," contributes efforts to control end-effector trajectories, positions, and orientations.

  13. Linear models: permutation methods

    USGS Publications Warehouse

    Cade, B.S.; Everitt, B.S.; Howell, D.C.

    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]...

  14. Linear force device

    NASA Technical Reports Server (NTRS)

    Clancy, John P.

    1988-01-01

    The object of the invention is to provide a mechanical force actuator which is lightweight and manipulatable and utilizes linear motion for push or pull forces while maintaining a constant overall length. The mechanical force producing mechanism comprises a linear actuator mechanism and a linear motion shaft mounted parallel to one another. The linear motion shaft is connected to a stationary or fixed housing and to a movable housing where the movable housing is mechanically actuated through actuator mechanism by either manual means or motor means. The housings are adapted to releasably receive a variety of jaw or pulling elements adapted for clamping or prying action. The stationary housing is adapted to be pivotally mounted to permit an angular position of the housing to allow the tool to adapt to skewed interfaces. The actuator mechanisms is operated by a gear train to obtain linear motion of the actuator mechanism.

  15. Localization of blood-group-related linear poly-N-acetyllactosamine structure in different human tissues by Griffonia simplicifolia agglutinin-II staining following endo-beta-galactosidase digestion.

    PubMed

    Ito, N; Kawahara, S; Hirano, Y; Morimura, Y; Nakajima, K; Uchida, K; Hirota, T

    1994-04-01

    Endo-beta-galactosidase from Escherichia freundii cleaves polylactosaminyl structures as follows: R-GlcNAc beta I-3Gal beta I-4GlcNac beta I-R' + H2O-->R-GlcNAc beta I-3Gal + GlcNAc beta I-R'. By staining with Griffonia simplicifolia agglutinin-II following the enzyme digestion, the distribution of R-GlcNAc beta I-3Gal beta I-4GlcNAc can be demonstrated in tissue sections. This carbohydrate chain is one of the backbone structures carrying the blood-group-related antigens and, thus, localization of this structure may provide detailed information about the distribution of variants with different backbone structures. Various formalin-fixed, paraffin-embedded tissue sections were stained by Griffonia simplicifolia agglutinin-II with or without prior enzyme digestion and the reactivity of the agglutinin imparted by enzyme digestion was studied in the following tissues and cells: pancreatic acinar cells, gastric surface mucosae, duct cells and mucous cells of salivary glands and tracheal glands, surface epithelium of trachea, goblet cells of large intestine, columnar epithelium of uterine cervical glands, distal and collecting tubules of kidney, certain cells of anterior lobe and colloid of middle lobe of pituitary glands, epithelial reticular cells and Hassall's corpuscles of thymus and Kupffer cells of liver. In gastric surface mucosae, the reactivity of the agglutinin appeared in non-secretor individuals but not in the secretor individuals, and in mucous cells of salivary and tracheal glands the reactivity appeared in Le(a- b-) non-secretor individuals but not in Le(a + b-) non-secretor or secretor individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Directions in General Relativity

    NASA Astrophysics Data System (ADS)

    Hu, B. L.; Ryan, M. P., Jr.; Vishveshwara, C. V.

    2005-10-01

    Preface; Dieter Brill: a spacetime perspective; 1. Thawing the frozen formalism: the difference between observables and what we observe A. Anderson; 2. Jacobi's action and the density of states J. D. Brown and J. W. York; 3. Decoherence of correlation histories E. Calzetta and B. L. Hu; 4. The initial value problem in light of Ashtekar's variables R. Capovilla, J. Dell and T. Jacobson; 5. Status report on an axiomatic basis for functional integration P. Cartier and C. DeWitt-Morette; 6. Solution of the coupled Einstein constraints on asymptotically Euclidean manifolds Y. Choquet-Bruhat; 7. Compact Cauchy horizons and Cauchy surfaces P. Chrusciel and J. Isenberg; 8. The classical electron J. M. Cohen and E. Mustafa; 9. Gauge (in)variance, mass and parity in D=3 revisited S. Deser; 10. Triality, exceptional Lie groups and Dirac operators F. Flaherty; 11. The reduction of the state vector and limitations on measurement in the quantum mechanics of closed systems J. B. Hartle; 12 Quantum linearization instabilities of de Sitter spacetime A. Higuchi; 13. What is the true description of charged black holes? G. T. Horowitz; 14. Limits on the adiabatic index in static stellar models L. Lindblom and A. K. M. Masood-ul-Alam; 15. On the relativity of rotation B. Mashhoon; 16. Recent progress and open problems in linearization stability V. E. Moncrief; 17. Brill waves N. Ó Murchadha; 18. You can't get there from here: constraints on topology change K. Schleich and D. M. Witt; 19. Time, measurement and information loss in quantum cosmology L. Smolin; 20. Impossible measurements on quantum fields R. Sorkin; 21. A new condition implying the existence of a constant mean curvature foliation F. J. Tipler; 22. Maximal slices in stationary spacetimes with ergoregions R. M. Wald; 23. (1 + 1) - Dimensional methods for general relativity J. H. Yoon; 24. Coalescence of primal gravity waves to make cosmological mass without matter D. E. Holz, W. A. Miller, M. Wakano and J. A. Wheeler.

  17. Linear ubiquitination in immunity.

    PubMed

    Shimizu, Yutaka; Taraborrelli, Lucia; Walczak, Henning

    2015-07-01

    Linear ubiquitination is a post-translational protein modification recently discovered to be crucial for innate and adaptive immune signaling. The function of linear ubiquitin chains is regulated at multiple levels: generation, recognition, and removal. These chains are generated by the linear ubiquitin chain assembly complex (LUBAC), the only known ubiquitin E3 capable of forming the linear ubiquitin linkage de novo. LUBAC is not only relevant for activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) in various signaling pathways, but importantly, it also regulates cell death downstream of immune receptors capable of inducing this response. Recognition of the linear ubiquitin linkage is specifically mediated by certain ubiquitin receptors, which is crucial for translation into the intended signaling outputs. LUBAC deficiency results in attenuated gene activation and increased cell death, causing pathologic conditions in both, mice, and humans. Removal of ubiquitin chains is mediated by deubiquitinases (DUBs). Two of them, OTULIN and CYLD, are constitutively associated with LUBAC. Here, we review the current knowledge on linear ubiquitination in immune signaling pathways and the biochemical mechanisms as to how linear polyubiquitin exerts its functions distinctly from those of other ubiquitin linkage types.

  18. Optimal Linear Control.

    DTIC Science & Technology

    1979-12-01

    OPTIMAL LINEAR CONTROL C.A. HARVEY M.G. SAFO NOV G. STEIN J.C. DOYLE HONEYWELL SYSTEMS & RESEARCH CENTER j 2600 RIDGWAY PARKWAY j [ MINNEAPOLIS...RECIPIENT’S CAT ALC-’ W.IMIJUff’? * J~’ CR2 15-238-4F TP P EI)ŕll * (~ Optimal Linear Control ~iOGRPR UBA m a M.G Lnar o Con_ _ _ _ _ _ R PORT__ _ _ I RE...Characterizations of optimal linear controls have been derived, from which guides for selecting the structure of the control system and the weights in

  19. Linear magnetic bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (Inventor)

    1983-01-01

    A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

  20. Reversibility of a Symmetric Linear Cellular Automata

    NASA Astrophysics Data System (ADS)

    Del Rey, A. Martín; Sánchez, G. Rodríguez

    The characterization of the size of the cellular space of a particular type of reversible symmetric linear cellular automata is introduced in this paper. Specifically, it is shown that those symmetric linear cellular with 2k + 1 cells, and whose transition matrix is a k-diagonal square band matrix with nonzero entries equal to 1 are reversible. Furthermore, in this case the inverse cellular automata are explicitly computed. Moreover, the reversibility condition is also studied for a general number of cells.