Science.gov

Sample records for a-site randomness effect

  1. Coordination effects on the electronic structure of the CuA site of cytochrome c oxidase

    NASA Astrophysics Data System (ADS)

    Koizumi, Kenichi; Shigeta, Yasuteru; Okuyama, Orio; Nakamura, Haruki; Takano, Yu

    2012-04-01

    The CuA site is the electron mediator in cytochrome c oxidase (CcO), providing an appropriate electronic structure for rapid electron transfer. We have studied the coordinating effects of His, Met, and the peptide carbonyl group of Glu of the CuA site, using the density functional theory. Our computation demonstrates that the His ligation provides strong orbital and electrostatic effects on the electronic structure of the CuA site, while that the Met coordination gives weak orbital and electrostatic effects. A coordination of the peptide carbonyl group affects the electronic structure of the CuA site only electrostatically.

  2. Application of the microtremor measurements to a site effect study

    NASA Astrophysics Data System (ADS)

    Rezaei, Sadegh; Choobbasti, Asskar Janalizadeh

    2017-07-01

    Earthquake has left much life and property damages. The occurrence of such events necessitates the execution of plans for combating the earthquakes. One of the most important methods for combating earthquakes includes assessing dynamic characteristics of soil and site effect. One of the methods by which one can state dynamic characteristics of the soil of an area is the measurement of microtremors. Microtremors are small-scale vibrations that occur in the ground and have an amplitude range of about 0.1-1 microns. Microtremor measurement is fast, applicable, cost-effective. Microtremor measurements were taken at 15 stations in the Babol, north of Iran. Regarding H/V spectral ratio method, peak frequency and amplification factor were calculated for all microtremor stations. According to the analysis, the peak frequency varies from 0.67 to 8.10 Hz within the study area. Also, the authors investigated the validity of the results by comparing them with SESAME guidelines and geotechnical conditions of study area. The microtremor analysis results are consistent with SESAME guidelines and geotechnical condition of study area. The results show that the microtremor observations are acceptable methods for assessing dynamic characteristics of soil and site effect in the Babol City.

  3. Effect of A-site Non-stoichiometry on LSCF Cathodes

    SciTech Connect

    Templeton, Jared W.; Lu, Zigui; Stevenson, Jeffry W.; Hardy, John S.

    2011-09-01

    LSCF Cathodes were explored when effected with A-site non-stoichiometry. At 700-800 C, the operating temperatures of intermediate temperature (IT-) SOFCs have enabled the use of stainless steels in the SOFC framework and current collectors, allowing significant reductions in cost. However, the lower operating temperatures of IT-SOFC's also result in significant decreases in power densities of cells with LSM cathodes due to their high activation energies. LSCF is a mixed ionic electronic conducting perovskite that exhibits higher performance than LSM/YSZ composites and shows potential as a replacement cathode. This study investigates the effect of A-site stoichiometry on the performance of LSCF cathodes. Cell tests showed that A-site and Sr-deficient LSCF cathodes consistently outperformed stoichiometric LSCF cathodes, exhibiting up to 10% higher cell power densities. It was also observed that all stoichiometric, A-site, and Sr-deficient LSCF cathodes degraded over time at similar rates. Contributions of ohmic and electrode polarization losses to cell degradation rates were similar regardless of cathode composition.

  4. Relatively random: context effects on perceived randomness and predicted outcomes.

    PubMed

    Matthews, William J

    2013-09-01

    This article concerns the effect of context on people's judgments about sequences of chance outcomes. In Experiment 1, participants judged whether sequences were produced by random, mechanical processes (such as a roulette wheel) or skilled human action (such as basketball shots). Sequences with lower alternation rates were judged more likely to result from human action. However, this effect was highly context-dependent: A moderate alternation rate was judged more likely to indicate a random physical process when encountered among sequences with lower alternation rates than when embedded among sequences with higher alternation rates. Experiment 2 found the same effect for predictions of the next outcome following a streak: A streak of 3 at the end of the sequence was judged less likely to continue by participants who had encountered shorter terminal streaks in previous trials than by those who had encountered longer ones. These contrast effects (a) help to explain variability in the types of sequences that are judged to be random and that elicit the gambler's fallacy, and urge caution about attempts to establish universal parameterizations of these effects; (b) are congruent with theories of sequence judgment that emphasize the importance of people's actual experiences with sequences of different kinds; (c) provide a link between models of sequence judgment and broader accounts of psychophysical/economic judgment; and (d) may offer new insight into individual differences in randomness judgments and sequence predictions. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  5. Relatively Random: Context Effects on Perceived Randomness and Predicted Outcomes

    ERIC Educational Resources Information Center

    Matthews, William J.

    2013-01-01

    This article concerns the effect of context on people's judgments about sequences of chance outcomes. In Experiment 1, participants judged whether sequences were produced by random, mechanical processes (such as a roulette wheel) or skilled human action (such as basketball shots). Sequences with lower alternation rates were judged more likely to…

  6. Effects on residential property values of proximity to a site contaminated with radioactive waste

    SciTech Connect

    Payne, B.A.; Olshansky, S.J.; Segel, T.E.

    1985-01-01

    An issue often raised by the public regarding projects that involve hazardous chemical or radioactive waste sites is whether distance from these sites affects residential property values. Previous research has studied changes in the housing market in communities near Three Mile Island after the 1979 accident and legal precedents of compensation for loss of property value because of proximity to hazardous areas. However, this research has not addressed effects on residential property values of proximity specifically to hazardous chemical or radioactive waste sites. The effects of the proximity of residence to such a site in West Chicago, Illinois - used for many years for disposal of thorium waste from processing ores - were investigated in this study. Single-family residence sales located within about 0.4 km of the West Chicago site were compared with residence sales located between 0.4 km and 1.6 km from the site. Trends in average annual selling prices were analyzed both before and after publicity appeared about the existence of the radioactive material at the site. Results indiate that older residences (built before 1950) located within about 0.4 km of the disposal site experienced a prolonged depression in selling prices after the publicity, in comparison with older residences located farther from the site and with all transactions on newer residences. These results confirm to some extent public perceptions and potentially raise legal issues associated with property values. Suggestions are provided for mitigative measures to alleviate these issues. 22 references, 1 figure.

  7. Effect Sizes in Cluster-Randomized Designs

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2007-01-01

    Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to…

  8. Effect Sizes in Cluster-Randomized Designs

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2007-01-01

    Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to…

  9. Effective Lagrangians and chiral random matrix theory

    SciTech Connect

    Halasz, M.A.; Verbaarschot, J.J.M.

    1995-08-15

    Recently, sum rules were derived for the inverse eigenvalues of the Dirac operator. They were obtained in two different ways: (i) starting from the low-energy effective Lagrangian and (ii) starting from a random matrix theory with the symmetries of the Dirac operator. This suggests that the effective theory can be obtained directly from the random matrix theory. Previously, this was shown for three or more colors with fundamental fermions. In this paper we construct the effective theory from a random matrix theory for two colors in the fundamental representation and for an arbitrary number of colors in the adjoint representation. We construct a fermionic partition function for Majorana fermions in Euclidean spacetime. Their reality condition is formulated in terms of complex conjugation of the second kind.

  10. The Random-Effect DINA Model

    ERIC Educational Resources Information Center

    Huang, Hung-Yu; Wang, Wen-Chung

    2014-01-01

    The DINA (deterministic input, noisy, and gate) model has been widely used in cognitive diagnosis tests and in the process of test development. The outcomes known as slip and guess are included in the DINA model function representing the responses to the items. This study aimed to extend the DINA model by using the random-effect approach to allow…

  11. The Random-Effect DINA Model

    ERIC Educational Resources Information Center

    Huang, Hung-Yu; Wang, Wen-Chung

    2014-01-01

    The DINA (deterministic input, noisy, and gate) model has been widely used in cognitive diagnosis tests and in the process of test development. The outcomes known as slip and guess are included in the DINA model function representing the responses to the items. This study aimed to extend the DINA model by using the random-effect approach to allow…

  12. Acousto-optic effect in random media

    NASA Astrophysics Data System (ADS)

    Hoskins, Jeremy G.; Schotland, John C.

    2017-03-01

    We consider the acousto-optic effect in a random medium. We derive the radiative transport equations that describe the propagation of multiply scattered light in a medium whose dielectric permittivity is modulated by an acoustic wave. Using this result, we present an analysis of the sensitivity of an acousto-optic measurement to the presence of a small absorbing inhomogeneity.

  13. Random-effects models for longitudinal data

    SciTech Connect

    Laird, N.M.; Ware, J.H.

    1982-12-01

    Models for the analysis of longitudinal data must recognize the relationship between serial observations on the same unit. Multivariate models with general covariance structure are often difficult to apply to highly unbalanced data, whereas two-stage random-effects models can be used easily. In two-stage models, the probability distributions for the response vectors of different individuals belong to a single family, but some random-effects parameters vary across individuals, with a distribution specified at the second stage. A general family of models is discussed, which includes both growth models and repeated-measures models as special cases. A unified approach to fitting these models, based on a combination of empirical Bayes and maximum likelihood estimation of model parameters and using the EM algorithm, is discussed. Two examples are taken from a current epidemiological study of the health effects of air pollution.

  14. Effective band structure of random alloys.

    PubMed

    Popescu, Voicu; Zunger, Alex

    2010-06-11

    Random substitutional A(x)B(1-x) alloys lack formal translational symmetry and thus cannot be described by the language of band-structure dispersion E(k(→)). Yet, many alloy experiments are interpreted phenomenologically precisely by constructs derived from wave vector k(→), e.g., effective masses or van Hove singularities. Here we use large supercells with randomly distributed A and B atoms, whereby many different local environments are allowed to coexist, and transform the eigenstates into an effective band structure (EBS) in the primitive cell using a spectral decomposition. The resulting EBS reveals the extent to which band characteristics are preserved or lost at different compositions, band indices, and k(→) points, showing in (In,Ga)N the rapid disintegration of the valence band Bloch character and in Ga(N,P) the appearance of a pinned impurity band.

  15. Random Test Run Length and Effectiveness

    NASA Technical Reports Server (NTRS)

    Andrews, James H.; Groce, Alex; Weston, Melissa; Xu, Ru-Gang

    2008-01-01

    A poorly understood but important factor in many applications of random testing is the selection of a maximum length for test runs. Given a limited time for testing, it is seldom clear whether executing a small number of long runs or a large number of short runs maximizes utility. It is generally expected that longer runs are more likely to expose failures -- which is certainly true with respect to runs shorter than the shortest failing trace. However, longer runs produce longer failing traces, requiring more effort from humans in debugging or more resources for automated minimization. In testing with feedback, increasing ranges for parameters may also cause the probability of failure to decrease in longer runs. We show that the choice of test length dramatically impacts the effectiveness of random testing, and that the patterns observed in simple models and predicted by analysis are useful in understanding effects observed.

  16. Random Test Run Length and Effectiveness

    NASA Technical Reports Server (NTRS)

    Andrews, James H.; Groce, Alex; Weston, Melissa; Xu, Ru-Gang

    2008-01-01

    A poorly understood but important factor in many applications of random testing is the selection of a maximum length for test runs. Given a limited time for testing, it is seldom clear whether executing a small number of long runs or a large number of short runs maximizes utility. It is generally expected that longer runs are more likely to expose failures -- which is certainly true with respect to runs shorter than the shortest failing trace. However, longer runs produce longer failing traces, requiring more effort from humans in debugging or more resources for automated minimization. In testing with feedback, increasing ranges for parameters may also cause the probability of failure to decrease in longer runs. We show that the choice of test length dramatically impacts the effectiveness of random testing, and that the patterns observed in simple models and predicted by analysis are useful in understanding effects observed.

  17. Estimating the causal effect of randomization versus treatment preference in a doubly randomized preference trial.

    PubMed

    Marcus, Sue M; Stuart, Elizabeth A; Wang, Pei; Shadish, William R; Steiner, Peter M

    2012-06-01

    Although randomized studies have high internal validity, generalizability of the estimated causal effect from randomized clinical trials to real-world clinical or educational practice may be limited. We consider the implication of randomized assignment to treatment, as compared with choice of preferred treatment as it occurs in real-world conditions. Compliance, engagement, or motivation may be better with a preferred treatment, and this can complicate the generalizability of results from randomized trials. The doubly randomized preference trial (DRPT) is a hybrid randomized and nonrandomized design that allows for estimation of the causal effect of randomization versus treatment preference. In the DRPT, individuals are first randomized to either randomized assignment or choice assignment. Those in the randomized assignment group are then randomized to treatment or control, and those in the choice group receive their preference of treatment versus control. Using the potential outcomes framework, we apply the algebra of conditional independence to show how the DRPT can be used to derive an unbiased estimate of the causal effect of randomization versus preference for each of the treatment and comparison conditions. Also, we show how these results can be implemented using full matching on the propensity score. The methodology is illustrated with a DRPT of introductory psychology students who were randomized to randomized assignment or preference of mathematics versus vocabulary training. We found a small to moderate benefit of preference versus randomization with respect to the mathematics outcome for those who received mathematics training.

  18. Polarity Effects in the Hisg Gene of Salmonella Require a Site within the Coding Sequence

    PubMed Central

    Ciampi, M. S.; Roth, J. R.

    1988-01-01

    A single site in the middle of the coding sequence of the hisG gene of Salmonella is required for most of the polar effect of mutations in this gene. Nonsense and insertion mutations mapping upstream of this point in the hisG gene all have strong polar effects on expression of downstream genes in the operon; mutations mapping promotor distal to this site have little or no polar effect. Two previously known hisG mutations, mapping in the region of the polarity site, abolish the polarity effect of insertion mutations mapping upstream of this region. New polarity site mutations have been selected which have lost the polar effect of upstream nonsense mutations. All mutations abolishing the function of the site are small deletions; three are identical, 28-bp deletions which have arisen independently. A fourth mutation is a deletion of 16 base pairs internal to the larger deletion. Several point mutations within this 16-bp region have no effect on the function of the polarity site. We believe that a small number of polarity sites of this type are responsible for polarity in all genes. The site in the hisG gene is more easily detected than most because it appears to be the only such site in the hisG gene and because it maps in the center of the coding sequence. PMID:3282985

  19. Effect of noise correlations on randomized benchmarking

    NASA Astrophysics Data System (ADS)

    Ball, Harrison; Stace, Thomas M.; Flammia, Steven T.; Biercuk, Michael J.

    2016-02-01

    Among the most popular and well-studied quantum characterization, verification, and validation techniques is randomized benchmarking (RB), an important statistical tool used to characterize the performance of physical logic operations useful in quantum information processing. In this work we provide a detailed mathematical treatment of the effect of temporal noise correlations on the outcomes of RB protocols. We provide a fully analytic framework capturing the accumulation of error in RB expressed in terms of a three-dimensional random walk in "Pauli space." Using this framework we derive the probability density function describing RB outcomes (averaged over noise) for both Markovian and correlated errors, which we show is generally described by a Γ distribution with shape and scale parameters depending on the correlation structure. Long temporal correlations impart large nonvanishing variance and skew in the distribution towards high-fidelity outcomes—consistent with existing experimental data—highlighting potential finite-sampling pitfalls and the divergence of the mean RB outcome from worst-case errors in the presence of noise correlations. We use the filter-transfer function formalism to reveal the underlying reason for these differences in terms of effective coherent averaging of correlated errors in certain random sequences. We conclude by commenting on the impact of these calculations on the utility of single-metric approaches to quantum characterization, verification, and validation.

  20. A Mixed Effects Randomized Item Response Model

    ERIC Educational Resources Information Center

    Fox, J.-P.; Wyrick, Cheryl

    2008-01-01

    The randomized response technique ensures that individual item responses, denoted as true item responses, are randomized before observing them and so-called randomized item responses are observed. A relationship is specified between randomized item response data and true item response data. True item response data are modeled with a (non)linear…

  1. Estimating the Causal Effect of Randomization versus Treatment Preference in a Doubly Randomized Preference Trial

    ERIC Educational Resources Information Center

    Marcus, Sue M.; Stuart, Elizabeth A.; Wang, Pei; Shadish, William R.; Steiner, Peter M.

    2012-01-01

    Although randomized studies have high internal validity, generalizability of the estimated causal effect from randomized clinical trials to real-world clinical or educational practice may be limited. We consider the implication of randomized assignment to treatment, as compared with choice of preferred treatment as it occurs in real-world…

  2. Effective cutoffs for detecting random, partially random, and nonrandom 370-item MMPI-2 short form protocols.

    PubMed

    Pinsoneault, Terry B

    2011-01-01

    The ability of the 370-item short form MMPI-2 (Butcher, Graham, Ben-Porath, Tellegen, Dahlstrom, & Kaemmer, 2001) validity scales to detect random protocols was investigated using samples of 500 nonrandom protocols, 250 half-random protocols, and 250 all-random protocols. The long-form cutoff of VRIN ≥ 80 was unable to detect protocols with either level of randomness. The long-form cutoffs of Fp ≥ 100 or F ≥ 100 were able to detect all-random but not half-random protocols. Alternative cutoffs for VRIN, Fp, and F were investigated and short-form subscales of those scales were developed to improve detection of partially random protocols. An algorithm using alternative cutoffs for the scales and the new subscales was highly effective, detecting almost all of the random protocols as well as the nonrandom protocols. A follow-up cross-validation study was conducted that confirmed the effectiveness of the algorithm.

  3. Effects of smooth random surface on fluid monolayer thermodynamics

    NASA Astrophysics Data System (ADS)

    Khlyupin, A. N.

    2016-11-01

    We consider the lattice gas approach to statistical mechanics of fluid adsorbed on random surfaces with fluid-fluid and fluid-surface potentials. It was shown that effective Hamiltonian contains quenched random interactions and random site fields. Their statistical features combine the properties of random geometry and fluid-fluid pair interaction potential. The high-temperature expansion leads to infinite-ranged random field model and Sherrington-Kirkpatrick spin-glass model. Thermodynamic properties are evaluated using replica theory procedure widely used to analyze quenched disorder systems. On the other hand we consider the random field model in random graph with finite connectivity instead of previous “infinite-ranged” approximations. This model has been investigated using finite connectivity technique. The replica symmetry ansatz for the order function is expressed in terms of an effective-field distribution. Analysis of random geometry effects on thermodynamic properties in such approach was done for the first time.

  4. A random effects epidemic-type aftershock sequence model.

    PubMed

    Lin, Feng-Chang

    2011-04-01

    We consider an extension of the temporal epidemic-type aftershock sequence (ETAS) model with random effects as a special case of a well-known doubly stochastic self-exciting point process. The new model arises from a deterministic function that is randomly scaled by a nonnegative random variable, which is unobservable but assumed to follow either positive stable or one-parameter gamma distribution with unit mean. Both random effects models are of interest although the one-parameter gamma random effects model is more popular when modeling associated survival times. Our estimation is based on the maximum likelihood approach with marginalized intensity. The methods are shown to perform well in simulation experiments. When applied to an earthquake sequence on the east coast of Taiwan, the extended model with positive stable random effects provides a better model fit, compared to the original ETAS model and the extended model with one-parameter gamma random effects.

  5. Random effects logistic models for analysing efficacy of a longitudinal randomized treatment with non-adherence.

    PubMed

    Small, Dylan S; Ten Have, Thomas R; Joffe, Marshall M; Cheng, Jing

    2006-06-30

    We present a random effects logistic approach for estimating the efficacy of treatment for compliers in a randomized trial with treatment non-adherence and longitudinal binary outcomes. We use our approach to analyse a primary care depression intervention trial. The use of a random effects model to estimate efficacy supplements intent-to-treat longitudinal analyses based on random effects logistic models that are commonly used in primary care depression research. Our estimation approach is an extension of Nagelkerke et al.'s instrumental variables approximation for cross-sectional binary outcomes. Our approach is easily implementable with standard random effects logistic regression software. We show through a simulation study that our approach provides reasonably accurate inferences for the setting of the depression trial under model assumptions. We also evaluate the sensitivity of our approach to model assumptions for the depression trial. Copyright (c) 2005 John Wiley & Sons, Ltd.

  6. General Framework for Effect Sizes in Cluster Randomized Experiments

    ERIC Educational Resources Information Center

    VanHoudnos, Nathan

    2016-01-01

    Cluster randomized experiments are ubiquitous in modern education research. Although a variety of modeling approaches are used to analyze these data, perhaps the most common methodology is a normal mixed effects model where some effects, such as the treatment effect, are regarded as fixed, and others, such as the effect of group random assignment…

  7. The Random-Effect Generalized Rating Scale Model

    ERIC Educational Resources Information Center

    Wang, Wen-Chung; Wu, Shiu-Lien

    2011-01-01

    Rating scale items have been widely used in educational and psychological tests. These items require people to make subjective judgments, and these subjective judgments usually involve randomness. To account for this randomness, Wang, Wilson, and Shih proposed the random-effect rating scale model in which the threshold parameters are treated as…

  8. The Random-Effect Generalized Rating Scale Model

    ERIC Educational Resources Information Center

    Wang, Wen-Chung; Wu, Shiu-Lien

    2011-01-01

    Rating scale items have been widely used in educational and psychological tests. These items require people to make subjective judgments, and these subjective judgments usually involve randomness. To account for this randomness, Wang, Wilson, and Shih proposed the random-effect rating scale model in which the threshold parameters are treated as…

  9. Estimation of the Nonlinear Random Coefficient Model when Some Random Effects Are Separable

    ERIC Educational Resources Information Center

    du Toit, Stephen H. C.; Cudeck, Robert

    2009-01-01

    A method is presented for marginal maximum likelihood estimation of the nonlinear random coefficient model when the response function has some linear parameters. This is done by writing the marginal distribution of the repeated measures as a conditional distribution of the response given the nonlinear random effects. The resulting distribution…

  10. Estimation of the Nonlinear Random Coefficient Model when Some Random Effects Are Separable

    ERIC Educational Resources Information Center

    du Toit, Stephen H. C.; Cudeck, Robert

    2009-01-01

    A method is presented for marginal maximum likelihood estimation of the nonlinear random coefficient model when the response function has some linear parameters. This is done by writing the marginal distribution of the repeated measures as a conditional distribution of the response given the nonlinear random effects. The resulting distribution…

  11. Effect of randomness in logistic maps

    NASA Astrophysics Data System (ADS)

    Khaleque, Abdul; Sen, Parongama

    2015-01-01

    We study a random logistic map xt+1 = atxt[1 - xt] where at are bounded (q1 ≤ at ≤ q2), random variables independently drawn from a distribution. xt does not show any regular behavior in time. We find that xt shows fully ergodic behavior when the maximum allowed value of at is 4. However , averaged over different realizations reaches a fixed point. For 1 ≤ at ≤ 4, the system shows nonchaotic behavior and the Lyapunov exponent is strongly dependent on the asymmetry of the distribution from which at is drawn. Chaotic behavior is seen to occur beyond a threshold value of q1(q2) when q2(q1) is varied. The most striking result is that the random map is chaotic even when q2 is less than the threshold value 3.5699⋯ at which chaos occurs in the nonrandom map. We also employ a different method in which a different set of random variables are used for the evolution of two initially identical x values, here the chaotic regime exists for all q1 ≠ q2 values.

  12. Bayesian nonparametric centered random effects models with variable selection.

    PubMed

    Yang, Mingan

    2013-03-01

    In a linear mixed effects model, it is common practice to assume that the random effects follow a parametric distribution such as a normal distribution with mean zero. However, in the case of variable selection, substantial violation of the normality assumption can potentially impact the subset selection and result in poor interpretation and even incorrect results. In nonparametric random effects models, the random effects generally have a nonzero mean, which causes an identifiability problem for the fixed effects that are paired with the random effects. In this article, we focus on a Bayesian method for variable selection. We characterize the subject-specific random effects nonparametrically with a Dirichlet process and resolve the bias simultaneously. In particular, we propose flexible modeling of the conditional distribution of the random effects with changes across the predictor space. The approach is implemented using a stochastic search Gibbs sampler to identify subsets of fixed effects and random effects to be included in the model. Simulations are provided to evaluate and compare the performance of our approach to the existing ones. We then apply the new approach to a real data example, cross-country and interlaboratory rodent uterotrophic bioassay.

  13. Summer School Effects in a Randomized Field Trial

    ERIC Educational Resources Information Center

    Zvoch, Keith; Stevens, Joseph J.

    2013-01-01

    This field-based randomized trial examined the effect of assignment to and participation in summer school for two moderately at-risk samples of struggling readers. Application of multiple regression models to difference scores capturing the change in summer reading fluency revealed that kindergarten students randomly assigned to summer school…

  14. Effects of random potentials in three-dimensional quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Zhao, Peng-Lu; Wang, An-Min; Liu, Guo-Zhu

    2017-06-01

    Three-dimensional quantum electrodynamics exhibits a number of interesting properties, such as dynamical chiral symmetry breaking, weak confinement, and non-Fermi-liquid behavior, and also has wide applications in condensed-matter physics. We study the effects of random potentials, which exist in almost all realistic condensed-matter systems, on the low-energy behaviors of massless Dirac fermions by means of renormalization-group method, and show that the role of random mass is significantly enhanced by the gauge interaction, whereas random scalar and vector potentials are insusceptible to the gauge interaction at the one-loop order. The static random potential breaks the Lorentz invariance, and as such induces unusual renormalization of fermion velocity. We then consider the case in which three types of random potentials coexist in the system. The random scalar potential is found to play a dominant role in the low-energy region, and drives the system to undergo a quantum phase transition.

  15. Semiparametric Approach to a Random Effects Quantile Regression Model

    PubMed Central

    Kim, Mi-Ok; Yang, Yunwen

    2011-01-01

    We consider a random effects quantile regression analysis of clustered data and propose a semiparametric approach using empirical likelihood. The random regression coefficients are assumed independent with a common mean, following parametrically specified distributions. The common mean corresponds to the population-average effects of explanatory variables on the conditional quantile of interest, while the random coefficients represent cluster specific deviations in the covariate effects. We formulate the estimation of the random coefficients as an estimating equations problem and use empirical likelihood to incorporate the parametric likelihood of the random coefficients. A likelihood-like statistical criterion function is yield, which we show is asymptotically concave in a neighborhood of the true parameter value and motivates its maximizer as a natural estimator. We use Markov Chain Monte Carlo (MCMC) samplers in the Bayesian framework, and propose the resulting quasi-posterior mean as an estimator. We show that the proposed estimator of the population-level parameter is asymptotically normal and the estimators of the random coefficients are shrunk toward the population-level parameter in the first order asymptotic sense. These asymptotic results do not require Gaussian random effects, and the empirical likelihood based likelihood-like criterion function is free of parameters related to the error densities. This makes the proposed approach both flexible and computationally simple. We illustrate the methodology with two real data examples. PMID:22347760

  16. Random diffusion and leverage effect in financial markets

    NASA Astrophysics Data System (ADS)

    Perelló, Josep; Masoliver, Jaume

    2003-03-01

    We prove that Brownian market models with random diffusion coefficients provide an exact measure of the leverage effect [J-P. Bouchaud et al., Phys. Rev. Lett. 87, 228701 (2001)]. This empirical fact asserts that past returns are anticorrelated with future diffusion coefficient. Several models with random diffusion have been suggested but without a quantitative study of the leverage effect. Our analysis lets us to fully estimate all parameters involved and allows a deeper study of correlated random diffusion models that may have practical implications for many aspects of financial markets.

  17. Random diffusion and leverage effect in financial markets.

    PubMed

    Perelló, Josep; Masoliver, Jaume

    2003-03-01

    We prove that Brownian market models with random diffusion coefficients provide an exact measure of the leverage effect [J-P. Bouchaud et al., Phys. Rev. Lett. 87, 228701 (2001)]. This empirical fact asserts that past returns are anticorrelated with future diffusion coefficient. Several models with random diffusion have been suggested but without a quantitative study of the leverage effect. Our analysis lets us to fully estimate all parameters involved and allows a deeper study of correlated random diffusion models that may have practical implications for many aspects of financial markets.

  18. Effects of random fields in an antiferromagnetic Ising bilayer film

    NASA Astrophysics Data System (ADS)

    Kaneyoshi, T.

    2017-10-01

    The magnetic properties (phase diagrams and magnetizations) of an antiferromagnetic Ising bilayer film with random fields are investigated by the use of the effective field theory with correlations. It is examined how an uncompensated magnetization can be realized in the system, due to the effects of random fields in the two layers. They show the tricritical, compensation point and reentrant phenomena, depending on these parameters.

  19. Particle morphology effects in random sequential adsorption

    NASA Astrophysics Data System (ADS)

    Budinski-Petković, Lj.; Lončarević, I.; Dujak, D.; Karač, A.; Šćepanović, J. R.; Jakšić, Z. M.; Vrhovac, S. B.

    2017-02-01

    The properties of the random sequential adsorption of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. The depositing objects are formed by self-avoiding lattice steps, whereby the size of the objects is gradually increased by wrapping the walks in several different ways. The aim of this work is to investigate the impact of the geometrical properties of the shapes on the jamming density θJ and on the temporal evolution of the coverage fraction θ (t ) . Our results suggest that the order of symmetry axis of a shape exerts a decisive influence on adsorption kinetics near the jamming limit θJ. The decay of probability for the insertion of a new particle onto a lattice is described in a broad range of the coverage θ by the product between the linear and the stretched exponential function for all examined objects. The corresponding fitting parameters are discussed within the context of the shape descriptors, such as rotational symmetry and the shape factor (parameter of nonsphericity) of the objects. Predictions following from our calculations suggest that the proposed fitting function for the insertion probability is consistent with the exponential approach of the coverage fraction θ (t ) to the jamming limit θJ.

  20. Comparative effects of precommercial thinning, urea fertilizer, and red alder in a site II, coast Douglas-fir plantation.

    Treesearch

    Richard E. Miller; Edmund L. Obermeyer; Harry W. Anderson

    1999-01-01

    We varied the number of red alder retained with 300 Douglas-fir per acre on a high-quality site in coastal Oregon. Alder densities of 0, 20, 40, and 80 per acre were tested. Our fifth treatment eliminated nitrogen-fixing alder, but substituted nitrogen fertilizer. Treatment 6 had neither thinning nor alder control. Treatments were randomly assigned within each of three...

  1. Effective trapping of random walkers in complex networks

    NASA Astrophysics Data System (ADS)

    Hwang, S.; Lee, D.-S.; Kahng, B.

    2012-04-01

    Exploring the World Wide Web has become one of the key issues in information science, specifically in view of its application to the PageRank-like algorithms used in search engines. The random walk approach has been employed to study such a problem. The probability of return to the origin (RTO) of random walks is inversely related to how information can be accessed during random surfing. We find analytically that the RTO probability for a given starting node shows a crossover from a slow to a fast decay behavior with time and the crossover time increases with the degree of the starting node. We remark that the RTO probability becomes almost constant in the early-time regime as the degree exponent approaches two. This result indicates that a random surfer can be effectively trapped at the hub and supports the necessity of the random jump strategy empirically used in the Google's search engine.

  2. Fixed effects, random effects and GEE: what are the differences?

    PubMed

    Gardiner, Joseph C; Luo, Zhehui; Roman, Lee Anne

    2009-01-30

    For analyses of longitudinal repeated-measures data, statistical methods include the random effects model, fixed effects model and the method of generalized estimating equations. We examine the assumptions that underlie these approaches to assessing covariate effects on the mean of a continuous, dichotomous or count outcome. Access to statistical software to implement these models has led to widespread application in numerous disciplines. However, careful consideration should be paid to their critical assumptions to ascertain which model might be appropriate in a given setting. To illustrate similarities and differences that might exist in empirical results, we use a study that assessed depressive symptoms in low-income pregnant women using a structured instrument with up to five assessments that spanned the pre-natal and post-natal periods. Understanding the conceptual differences between the methods is important in their proper application even though empirically they might not differ substantively. The choice of model in specific applications would depend on the relevant questions being addressed, which in turn informs the type of design and data collection that would be relevant. Copyright (c) 2008 John Wiley & Sons, Ltd.

  3. Effect of Mutations on the Binding of Kanamycin-B to RNA Hairpins Derived from the Mycobacterium tuberculosis Ribosomal A-Site.

    PubMed

    Truitt, Amber R; Choi, Bok-Eum; Li, Jenny; Soto, Ana Maria

    2015-12-29

    Kanamycin is an aminoglycoside antibiotic used in the treatment of drug-resistant tuberculosis. Mutations at the rRNA A-site have been associated with kanamycin resistance in Mycobacterium tuberculosis clinical isolates. Understanding the effect of these mutations on the conformation of the M. tuberculosis A-site is critical for understanding the mechanisms of antibiotic resistance in M. tuberculosis. In this work, we have studied RNA hairpins derived from the M. tuberculosis A-site, the wild type and three mutants at the following positions (M. tuberculosis/Escherichia coli numbering): A1400/1408 → G, C1401/1409 → U, and the double mutant G1483/1491 C1401/1409 → UA. Specifically, we used circular dichroism, ultraviolet spectroscopy, and fluorescence spectroscopy to characterize the conformation, stability, and binding affinity of kanamycin-B and other aminoglycoside antibiotics for these RNA hairpins. Our results show that the mutations affect the conformation of the decoding site, with the mutations at position 1401/1409 resulting in significant destabilizations. Interestingly, the mutants bind paromomycin with weaker affinity than the wild type, but they bind kanamycin-B with similar affinity than the wild type. The results suggest that the presence of mutations does not prevent kanamycin-B from binding. Instead, kanamycin may promote different interactions with a third partner in the mutants compared to the wild type. Furthermore, our results with longer and shorter hairpins suggest that the region of the A-site that varies among organisms may have modulating effects on the binding and interactions of the A-site.

  4. Analog model for quantum gravity effects: phonons in random fluids.

    PubMed

    Krein, G; Menezes, G; Svaiter, N F

    2010-09-24

    We describe an analog model for quantum gravity effects in condensed matter physics. The situation discussed is that of phonons propagating in a fluid with a random velocity wave equation. We consider that there are random fluctuations in the reciprocal of the bulk modulus of the system and study free phonons in the presence of Gaussian colored noise with zero mean. We show that, in this model, after performing the random averages over the noise function a free conventional scalar quantum field theory describing free phonons becomes a self-interacting model.

  5. Empirical vs natural weighting in random effects meta-analysis.

    PubMed

    Shuster, Jonathan J

    2010-05-30

    This article brings into serious question the validity of empirically based weighting in random effects meta-analysis. These methods treat sample sizes as non-random, whereas they need to be part of the random effects analysis. It will be demonstrated that empirical weighting risks substantial bias. Two alternate methods are proposed. The first estimates the arithmetic mean of the population of study effect sizes per the classical model for random effects meta-analysis. We show that anything other than an unweighted mean of study effect sizes will risk serious bias for this targeted parameter. The second method estimates a patient level effect size, something quite different from the first. To prevent inconsistent estimation for this population parameter, the study effect sizes must be weighted in proportion to their total sample sizes for the trial. The two approaches will be presented for a meta-analysis of a nasal decongestant, while at the same time will produce counter-intuitive results for the DerSimonian-Laird approach, the most popular empirically based weighted method. It is concluded that all past publications based on empirically weighted random effects meta-analysis should be revisited to see if the qualitative conclusions hold up under the methods proposed herein. It is also recommended that empirically based weighted random effects meta-analysis not be used in the future, unless strong cautions about the assumptions underlying these analyses are stated, and at a minimum, some form of secondary analysis based on the principles set forth in this article be provided to supplement the primary analysis. Copyright (c) 2009 John Wiley & Sons, Ltd.

  6. Empirical vs. natural weighting in random effects meta-analysis

    PubMed Central

    Shuster, Jonathan J

    2013-01-01

    SUMMARY This paper brings into serious question the validity of empirically based weighting in random effects Meta-Analysis. These methods treat sample sizes as non-random, whereas they need to be part of the random effects analysis. It will be demonstrated that empirical weighting risks substantial bias. Two alternate methods are proposed. The first estimates the arithmetic mean of the population of study effect sizes per the classical model for random effects meta-analysis. We show that anything other than an unweighted mean of study effect sizes will risk serious bias for this targeted parameter. The second method estimates a patient level effect size, something quite different from the first. To prevent inconsistent estimation for this population parameter, the study effect sizes must be weighted in proportion to their total sample sizes for the trial. The two approaches will be presented for a meta-analysis of a nasal decongestant, while at the same time will produce counter-intuitive results for the DerSimonian-Laird approach, the most popular empirically based weighted method. It is concluded that all past publications based on empirically weighted random effects meta-analysis should be revisited to see if the qualitative conclusions hold up under the methods proposed herein. It is also recommended that empirically based weighted random effects meta-analysis not be used in the future, unless strong cautions about the assumptions underlying these analyses are stated, and at a minimum, some form of secondary analysis based on the principles set forth in this article be provided to supplement the primary analysis. PMID:19475538

  7. Macroscopic random Paschen-Back effect in ultracold atomic gases

    NASA Astrophysics Data System (ADS)

    Modugno, M.; Sherman, E. Ya.; Konotop, V. V.

    2017-06-01

    We consider spin- and density-related properties of single-particle states in a one-dimensional system with random spin-orbit coupling. We show that the presence of an additional Zeeman field Δ induces both nonlinear spin polarization and delocalization of states localized at Δ =0 , corresponding to a random macroscopic analog of the Paschen-Back effect. While the conventional Paschen-Back effect corresponds to a saturated Δ dependence of the spin polarization, here the gradual suppression of the spin-orbit coupling effects by the Zeeman field is responsible both for the spin saturation and delocalization of the particles.

  8. Fixed and random effects selection in linear and logistic models.

    PubMed

    Kinney, Satkartar K; Dunson, David B

    2007-09-01

    We address the problem of selecting which variables should be included in the fixed and random components of logistic mixed effects models for correlated data. A fully Bayesian variable selection is implemented using a stochastic search Gibbs sampler to estimate the exact model-averaged posterior distribution. This approach automatically identifies subsets of predictors having nonzero fixed effect coefficients or nonzero random effects variance, while allowing uncertainty in the model selection process. Default priors are proposed for the variance components and an efficient parameter expansion Gibbs sampler is developed for posterior computation. The approach is illustrated using simulated data and an epidemiologic example.

  9. Application of Poisson random effect models for highway network screening.

    PubMed

    Jiang, Ximiao; Abdel-Aty, Mohamed; Alamili, Samer

    2014-02-01

    In recent years, Bayesian random effect models that account for the temporal and spatial correlations of crash data became popular in traffic safety research. This study employs random effect Poisson Log-Normal models for crash risk hotspot identification. Both the temporal and spatial correlations of crash data were considered. Potential for Safety Improvement (PSI) were adopted as a measure of the crash risk. Using the fatal and injury crashes that occurred on urban 4-lane divided arterials from 2006 to 2009 in the Central Florida area, the random effect approaches were compared to the traditional Empirical Bayesian (EB) method and the conventional Bayesian Poisson Log-Normal model. A series of method examination tests were conducted to evaluate the performance of different approaches. These tests include the previously developed site consistence test, method consistence test, total rank difference test, and the modified total score test, as well as the newly proposed total safety performance measure difference test. Results show that the Bayesian Poisson model accounting for both temporal and spatial random effects (PTSRE) outperforms the model that with only temporal random effect, and both are superior to the conventional Poisson Log-Normal model (PLN) and the EB model in the fitting of crash data. Additionally, the method evaluation tests indicate that the PTSRE model is significantly superior to the PLN model and the EB model in consistently identifying hotspots during successive time periods. The results suggest that the PTSRE model is a superior alternative for road site crash risk hotspot identification.

  10. Random Effects Structure for Confirmatory Hypothesis Testing: Keep It Maximal

    ERIC Educational Resources Information Center

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the…

  11. Effects of random fields in an antiferromagnetic Ising spin glass

    PubMed

    Vieira; Nobre; Yokoi

    2000-05-01

    The effects of random fields on the two-sublattice infinite-ranged Ising spin-glass model are investigated. This model is expected to be appropriate as a mean-field description of antiferromagnetic spin glasses such as FexMn1-xTiO3. Within replica-symmetric calculations, we study the influence of Gaussian and bimodal random fields on the phase transitions and phase diagrams. It is shown that, in the presence of random fields, the first-order transitions are weakened and may become continuous. Also, the antiferromagnetic phases are always destroyed by sufficiently strong random fields. A qualitative comparison with existing experimental results and the limitations of the present calculations are discussed.

  12. Random Effects: Variance Is the Spice of Life.

    PubMed

    Jupiter, Daniel C

    Covariates in regression analyses allow us to understand how independent variables of interest impact our dependent outcome variable. Often, we consider fixed effects covariates (e.g., gender or diabetes status) for which we examine subjects at each value of the covariate. We examine both men and women and, within each gender, examine both diabetic and nondiabetic patients. Occasionally, however, we consider random effects covariates for which we do not examine subjects at every value. For example, we examine patients from only a sample of hospitals and, within each hospital, examine both diabetic and nondiabetic patients. The random sampling of hospitals is in contrast to the complete coverage of all genders. In this column I explore the differences in meaning and analysis when thinking about fixed and random effects variables. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  13. A Gompertzian model with random effects to cervical cancer growth

    SciTech Connect

    Mazlan, Mazma Syahidatul Ayuni; Rosli, Norhayati

    2015-05-15

    In this paper, a Gompertzian model with random effects is introduced to describe the cervical cancer growth. The parameters values of the mathematical model are estimated via maximum likehood estimation. We apply 4-stage Runge-Kutta (SRK4) for solving the stochastic model numerically. The efficiency of mathematical model is measured by comparing the simulated result and the clinical data of the cervical cancer growth. Low values of root mean-square error (RMSE) of Gompertzian model with random effect indicate good fits.

  14. The blocked-random effect in pictures and words.

    PubMed

    Toglia, M P; Hinman, P J; Dayton, B S; Catalano, J F

    1997-06-01

    Picture and word recall was examined in conjunction with list organization. 60 subjects studied a list of 30 items, either words or their pictorial equivalents. The 30 words/pictures, members of five conceptual categories, each represented by six exemplars, were presented either blocked by category or in a random order. While pictures were recalled better than words and a standard blocked-random effect was observed, the interaction indicated that the recall advantage of a blocked presentation was restricted to the word lists. A similar pattern emerged for clustering. These findings are discussed in terms of limitations upon the pictorial superiority effect.

  15. A Gompertzian model with random effects to cervical cancer growth

    NASA Astrophysics Data System (ADS)

    Mazlan, Mazma Syahidatul Ayuni; Rosli, Norhayati

    2015-05-01

    In this paper, a Gompertzian model with random effects is introduced to describe the cervical cancer growth. The parameters values of the mathematical model are estimated via maximum likehood estimation. We apply 4-stage Runge-Kutta (SRK4) for solving the stochastic model numerically. The efficiency of mathematical model is measured by comparing the simulated result and the clinical data of the cervical cancer growth. Low values of root mean-square error (RMSE) of Gompertzian model with random effect indicate good fits.

  16. Power analysis for random-effects meta-analysis

    PubMed Central

    Jackson, Dan; Turner, Rebecca

    2017-01-01

    One of the reasons for the popularity of meta-analysis is the notion that these analyses will possess more power to detect effects than individual studies. This is inevitably the case under a fixed-effect model. However, the inclusion of the between-study variance in the random-effects model, and the need to estimate this parameter, can have unfortunate implications for this power. We develop methods for assessing the power of random-effects meta-analyses, and the average power of the individual studies that contribute to meta-analyses, so that these powers can be compared. In addition to deriving new analytical results and methods, we apply our methods to 1991 meta-analyses taken from the Cochrane Database of Systematic Reviews to retrospectively calculate their powers. We find that, in practice, 5 or more studies are needed to reasonably consistently achieve powers from random-effects meta-analyses that are greater than the studies that contribute to them. Not only is statistical inference under the random-effects model challenging when there are very few studies but also less worthwhile in such cases. The assumption that meta-analysis will result in an increase in power is challenged by our findings. PMID:28378395

  17. A-Site (MCe) Substitution Effects on the Structures and Properties of CaBi4Ti4O15 Ceramics

    NASA Astrophysics Data System (ADS)

    Yan, Haixue; Li, Chengen; Zhou, Jiaguang; Zhu, Weimin; He, Lianxin; Song, Yuxin

    2000-11-01

    We investigated the effect of A-site compound substitution on the structures and properties of Ca0.8(MCe)0.1Bi4Ti4O15 (M denotes Li, Na and K) ceramics. The samples were prepared by the conventional ceramic technique. Sintering characteristics of Ca0.8(MCe)0.1Bi4Ti4O15 and CaBi4Ti4O15 ceramics were discussed. X-ray powder diffraction patterns of the three modified CBT-based compounds show a single phase of bismuth oxide layer type structure with m=4. The hysteresis loops of polarization versus electric field of the four compounds were also measured. A-site compound substitution improves the piezoelectric properties and the high-temperature resistivity of these materials. A-site (LiCe) and (KCe) substitution not only improves the Curie temperature but also decreases the temperature coefficient of dielectric constant (TK\\varepsilon). Among the three modified ceramics, only the Curie temperature of Ca0.8(NaCe)0.1Bi4Ti4O15 is lower than that of CaBi4Ti4O15; however, its TK\\varepsilon is the lowest. As a result, all the three modified CBT-based ceramics were found to be excellent high-temperature piezoelectric materials.

  18. The Effect of Random Voids in the Modified Gurson Model

    NASA Astrophysics Data System (ADS)

    Fei, Huiyang; Yazzie, Kyle; Chawla, Nikhilesh; Jiang, Hanqing

    2012-02-01

    The porous plasticity model (usually referred to as the Gurson-Tvergaard-Needleman model or modified Gurson model) has been widely used in the study of microvoid-induced ductile fracture. In this paper, we studied the effects of random voids on the porous plasticity model. Finite-element simulations were conducted to study a copper/tin/copper joint bar under uniaxial tension using the commercial finite-element package ABAQUS. A randomly distributed initial void volume fraction with different types of distribution was introduced, and the effects of this randomness on the crack path and macroscopic stress-strain behavior were studied. It was found that consideration of the random voids is able to capture more detailed and localized deformation features, such as different crack paths and different ultimate tensile strengths, and meanwhile does not change the macroscopic stress-strain behavior. It seems that the random voids are able to qualitatively explain the scattered observations in experiments while keeping the macroscopic measurements consistent.

  19. Polarity effects in the hisG gene of salmonella require a site within the coding sequence.

    PubMed

    Ciampi, M S; Roth, J R

    1988-02-01

    A single site in the middle of the coding sequence of the hisG gene of Salmonella is required for most of the polar effect of mutations in this gene. Nonsense and insertion mutations mapping upstream of this point in the hisG gene all have strong polar effects on expression of downstream genes in the operon; mutations mapping promotor distal to this site have little or no polar effect. Two previously known hisG mutations, mapping in the region of the polarity site, abolish the polarity effect of insertion mutations mapping upstream of this region. New polarity site mutations have been selected which have lost the polar effect of upstream nonsense mutations. All mutations abolishing the function of the site are small deletions; three are identical, 28-bp deletions which have arisen independently. A fourth mutation is a deletion of 16 base pairs internal to the larger deletion. Several point mutations within this 16-bp region have no effect on the function of the polarity site. We believe that a small number of polarity sites of this type are responsible for polarity in all genes. The site in the hisG gene is more easily detected than most because it appears to be the only such site in the hisG gene and because it maps in the center of the coding sequence.

  20. Random effects structure for confirmatory hypothesis testing: Keep it maximal

    PubMed Central

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the standards that have been in place for many decades. Through theoretical arguments and Monte Carlo simulation, we show that LMEMs generalize best when they include the maximal random effects structure justified by the design. The generalization performance of LMEMs including data-driven random effects structures strongly depends upon modeling criteria and sample size, yielding reasonable results on moderately-sized samples when conservative criteria are used, but with little or no power advantage over maximal models. Finally, random-intercepts-only LMEMs used on within-subjects and/or within-items data from populations where subjects and/or items vary in their sensitivity to experimental manipulations always generalize worse than separate F1 and F2 tests, and in many cases, even worse than F1 alone. Maximal LMEMs should be the ‘gold standard’ for confirmatory hypothesis testing in psycholinguistics and beyond. PMID:24403724

  1. Modelling the random effects covariance matrix in longitudinal data.

    PubMed

    Daniels, Michael J; Zhao, Yan D

    2003-05-30

    A common class of models for longitudinal data are random effects (mixed) models. In these models, the random effects covariance matrix is typically assumed constant across subject. However, in many situations this matrix may differ by measured covariates. In this paper, we propose an approach to model the random effects covariance matrix by using a special Cholesky decomposition of the matrix. In particular, we will allow the parameters that result from this decomposition to depend on subject-specific covariates and also explore ways to parsimoniously model these parameters. An advantage of this parameterization is that there is no concern about the positive definiteness of the resulting estimator of the covariance matrix. In addition, the parameters resulting from this decomposition have a sensible interpretation. We propose fully Bayesian modelling for which a simple Gibbs sampler can be implemented to sample from the posterior distribution of the parameters. We illustrate these models on data from depression studies and examine the impact of heterogeneity in the covariance matrix on estimation of both fixed and random effects.

  2. Computer-Assisted Dieting: Effects of a Randomized Nutrition Intervention

    ERIC Educational Resources Information Center

    Schroder, Kerstin E. E.

    2011-01-01

    Objectives: To compare the effects of a computer-assisted dieting intervention (CAD) with and without self-management training on dieting among 55 overweight and obese adults. Methods: Random assignment to a single-session nutrition intervention (CAD-only) or a combined CAD plus self-management group intervention (CADG). Dependent variables were…

  3. Effect Sizes in Three-Level Cluster-Randomized Experiments

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2011-01-01

    Research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Many of these designs involve two levels of clustering or nesting (students within classes and classes within schools). Researchers would like to compute effect size indexes based on the standardized mean difference to…

  4. Family Maltreatment, Substance Problems, and Suicidality: Randomized Prevention Effectiveness Trial

    DTIC Science & Technology

    2008-02-01

    another institution? NO YES → Is it a multi-center clinical trial (e.g., Oncology Group, ACTG, Industry-initiated)? YES NO → Provide name(s...NO YES → You must comply with the clinical trial registration requirements detailed at http://www.stonybrook.edu/research/humans...and Suicidality: Randomized Prevention Effectiveness Trial PRINCIPAL INVESTIGATOR: Richard E. Heyman, Ph.D

  5. Performance of Random Effects Model Estimators under Complex Sampling Designs

    ERIC Educational Resources Information Center

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  6. Computer-Assisted Dieting: Effects of a Randomized Nutrition Intervention

    ERIC Educational Resources Information Center

    Schroder, Kerstin E. E.

    2011-01-01

    Objectives: To compare the effects of a computer-assisted dieting intervention (CAD) with and without self-management training on dieting among 55 overweight and obese adults. Methods: Random assignment to a single-session nutrition intervention (CAD-only) or a combined CAD plus self-management group intervention (CADG). Dependent variables were…

  7. Modelling the random effects covariance matrix in longitudinal data

    PubMed Central

    Daniels, Michael J.; Zhao, Yan D.

    2009-01-01

    SUMMARY A common class of models for longitudinal data are random effects (mixed) models. In these models, the random effects covariance matrix is typically assumed constant across subject. However, in many situations this matrix may differ by measured covariates. In this paper, we propose an approach to model the random effects covariance matrix by using a special Cholesky decomposition of the matrix. In particular, we will allow the parameters that result from this decomposition to depend on subject-specific covariates and also explore ways to parsimoniously model these parameters. An advantage of this parameterization is that there is no concern about the positive definiteness of the resulting estimator of the covariance matrix. In addition, the parameters resulting from this decomposition have a sensible interpretation. We propose fully Bayesian modelling for which a simple Gibbs sampler can be implemented to sample from the posterior distribution of the parameters. We illustrate these models on data from depression studies and examine the impact of heterogeneity in the covariance matrix on estimation of both fixed and random effects. PMID:12720301

  8. Performance of Random Effects Model Estimators under Complex Sampling Designs

    ERIC Educational Resources Information Center

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  9. Effect Sizes in Three-Level Cluster-Randomized Experiments

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2011-01-01

    Research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Many of these designs involve two levels of clustering or nesting (students within classes and classes within schools). Researchers would like to compute effect size indexes based on the standardized mean difference to…

  10. Nonlinear mixed-effects models for pharmacokinetic data analysis: assessment of the random-effects distribution.

    PubMed

    Drikvandi, Reza

    2017-02-13

    Nonlinear mixed-effects models are frequently used for pharmacokinetic data analysis, and they account for inter-subject variability in pharmacokinetic parameters by incorporating subject-specific random effects into the model. The random effects are often assumed to follow a (multivariate) normal distribution. However, many articles have shown that misspecifying the random-effects distribution can introduce bias in the estimates of parameters and affect inferences about the random effects themselves, such as estimation of the inter-subject variability. Because random effects are unobservable latent variables, it is difficult to assess their distribution. In a recent paper we developed a diagnostic tool based on the so-called gradient function to assess the random-effects distribution in mixed models. There we evaluated the gradient function for generalized liner mixed models and in the presence of a single random effect. However, assessing the random-effects distribution in nonlinear mixed-effects models is more challenging, especially when multiple random effects are present, and therefore the results from linear and generalized linear mixed models may not be valid for such nonlinear models. In this paper, we further investigate the gradient function and evaluate its performance for such nonlinear mixed-effects models which are common in pharmacokinetics and pharmacodynamics. We use simulations as well as real data from an intensive pharmacokinetic study to illustrate the proposed diagnostic tool.

  11. Comparative effects of urea fertilizer and red alder in a site III, coast Douglas-fir plantation in the Washington Cascade Range.

    Treesearch

    Richard E. Miller; Harry W. Anderson; Marshall Murray; Rick. Leon

    2005-01-01

    Five randomly assigned treatments were used to quantify effects of adding varying numbers of red alder (Alnus rubra Bong.) or nitrogen (N) fertilization on growth of a 10-year-old conifer plantation at a medium quality site in the western Washington Cascade Range. Zero, 20, 40, and 80 alder trees per acre were retained along with about 300 conifers...

  12. Effective thermal conductivity of a thin, randomly oriented composite material

    SciTech Connect

    Phelan, P.E.; Niemann, R.C.

    1997-10-01

    The thermal conductivity of a randomly oriented composite material is modeled using a probabilistic approach in order to determine if a size effect exists for the thermal conductivity at small composite thicknesses. The numerical scheme employs a random number generator to position the filler elements, which have a relatively high thermal conductivity, within a matrix having a relative low thermal conductivity. The results indicate that, below some threshold thickness, the composite thermal conductivity is independent of thickness. The threshold thickness increases for increasing filler fraction and increasing k{sub f}/k{sub m}, the ratio between the filler and matrix thermal conductivities.

  13. Effects of Blockiness on the phase behavior of random copolymers

    NASA Astrophysics Data System (ADS)

    Vanderwoude, Gordon; Shi, An-Chang

    Theoretical study of random block copolymers remains a challenging topic due in part to the sheer enormity of their phase space. In this study we use the self-consistent field theory to investigate the phase behaviour of linear (AB)n-type and (AB)n-C-type multiblock copolymers with randomly distributed A and B blocks. In particular, we examine the effect of ``blockiness'' of the random copolymers on the formation of ordered phases. The blockiness can be quantified by the average length of individual A or B blocks, which can be taken as a measure of the heterogeneity of the random copolymers. We observed that the critical value of the χ parameter, at which the order-disorder transition occurs, decreases with increasing blockiness in the (AB)n copolymers. We also observed that the phase behaviour of the (AB)n-C copolymers depends strongly on the blockiness of the random chain. In particular, the blockiness governs whether or not the A/B blocks can phase separate within the A/B domains, thus dictating whether the (AB)n-C behaves as A/B-C diblock copolymers or as ABC terpolymers. The theoretical phase diagrams will be compared with available experiments.

  14. Effects of cation disorder and size on metamagnetism in A-site substituted Pr0.5Ca0.5MnO3 system

    NASA Astrophysics Data System (ADS)

    Mavani, K. R.; Paulose, P. L.

    2005-04-01

    The effects of A-site cation disorder and size on metamagnetism of ABO3 type charge and orbital ordered Pr0.5Ca0.5MnO3 system have been studied by substituting Ba+2 for Ca+2 or La+3 for Pr+3. Substitution of 5% Ba+2 or 5% La+3 drastically reduces the critical magnetic field (Hc) for metamagnetism and induces successive steplike metamagnetic transitions at low temperatures. Interestingly, with further increase in substitution, Hc rises. We find that there is a sharp decrease in electrical resistivity corresponding to the metamagnetic transitions, which is indicative of strongly correlated magnetic and electronic transitions in these manganites.

  15. Magnetodielectric effects in A -site cation-ordered chromate spinels Li M C r4O8 (M =Ga and In)

    NASA Astrophysics Data System (ADS)

    Saha, Rana; Fauth, Francois; Avdeev, Maxim; Kayser, Paula; Kennedy, Brendan J.; Sundaresan, A.

    2016-08-01

    We report the occurrence of a magnetodielectric effect and its correlation with structure and magnetism in the A -site ordered chromate spinel oxides Li M C r4O8 (M =Ga , In). In addition to magnetic and dielectric measurements, temperature dependent synchrotron and neutron diffraction experiments have been carried out for the Ga compound. The results are compared and contrasted with that of a corresponding conventional B -site magnetic chromate spinel oxide, ZnC r2O4 . Like ZnC r2O4 , the A -site ordered chromate spinels exhibit a magnetodielectric effect at the magnetic ordering temperature (TN˜13 -15 K ), resulting from magnetoelastic coupling through a spin Jahn-Teller effect. While the presence of a broad magnetic anomaly, associated with a short-range magnetic ordering (TSO˜45 K ) in ZnC r2O4 , does not cause any dielectric anomaly, a sharp change in dielectric constant has been observed in LiInC r4O8 at the magnetic anomaly, which is associated with the opening of a spin gap (TSG˜60 K ). Contrary to the In compound, a broad dielectric anomaly exists at the onset of short-range antiferromagnetic ordering (TSO˜55 K ) in LiGaC r4O8 . The differences in dielectric behavior of these compounds have been discussed in terms of breathing distortion of the C r4 tetrahedra.

  16. A site effect study in the Verchiano valley during the 1997 Umbria-Marche (Central Italy) earthquakes

    NASA Astrophysics Data System (ADS)

    Gaffet, Stephane; Cultrera, Giovanna; Dietrich, Michel; Courboulex, Francoise; Marra, Fabrizio; Bouchon, Michel; Caserta, Arrigo; Cornou, Cecile; Deschamps, Anne; Glot, Jean-Paul; Guiguet, Robert

    Strong site effects were observed during the two M W 5.7 and M W 6.0 main shocks of the Colfiorito seismic crisis which occured on September 26, 1997 in Umbria-Marche (Central Italy).The most obvious indications of these effects are the dramatic differences in damage shown by buildings of similar construction in neighboring villages.Such observations were specifically made in the Verchiano valley in the fault area, 15 km south of Colfiorito where the Verchiano village and the Colle and Camino hamlets were heavily damaged (MCS intensity IX-X) since the first main shock of 1997/09/26,while in contrast, the Curasci village located 2 km eastwards remains almost intact.In order to study the anomalous ground motion amplifications in this area, an array of 11, 3-components seismo- and accelero-meters was set up during the 1997/10/20-24 period, extending from the western side of the valley, up to the top of Mount San Salvatore, going accross the Colle and Curasci hamlets.During the experiment, 67 aftershocks enlightened the valley from the Colfiorito (10 km north) and the Sellano (6 km south) active swarms.Seismic refraction experiments were conducted at the same time in the 500 m wide, 1500 m long Verchiano valley in order to determine the thickness and main characteristics of the alluvial infilling.The main results are: (i) compared to the valley side ground motion, and for all the events, recordings in the central part of the valley (piana di Verchiano) show relative amplification of 10 with a clear lengthening of the seismogram duration by a factor of 2 - (ii) broad band relative amplification of 6-8 is also clearly identified at the top of the Mount San Salvatore overhanging the valley - (iii) any of the site effect measurements done explains by itself the strongly contrasted damage observed at Colle and Curasci: i.e. the modification of the near-field radiation pattern by interaction with the free heterogeneous surface may have induced local shadow zones that saved

  17. Neighborhood Effects in a Behavioral Randomized Controlled Trial

    PubMed Central

    Pruitt, Sandi L.; Leonard, Tammy; Murdoch, James; Hughes, Amy; McQueen, Amy; Gupta, Samir

    2015-01-01

    Randomized controlled trials (RCTs) of interventions intended to modify health behaviors may be influenced by neighborhood effects which can impede unbiased estimation of intervention effects. Examining a RCT designed to increase colorectal cancer (CRC) screening (N=5,628), we found statistically significant neighborhood effects: average CRC test use among neighboring study participants was significantly and positively associated with individual patient’s CRC test use. This potentially important spatially-varying covariate has not previously been considered in a RCT. Our results suggest that future RCTs of health behavior interventions should assess potential social interactions between participants, which may cause intervention arm contamination and may bias effect size estimation. PMID:25456014

  18. Effective diffusion equation in a random velocity field

    NASA Technical Reports Server (NTRS)

    Vinals, Jorge; Sekerka, Robert F.

    1992-01-01

    The effects are studied of assumed random velocity fields on diffusion in a binary fluid. Random velocity fields can result, for example, from the high-frequency components of residual accelerations onboard spacecraft (often called g-jitter). An effective diffusion equation is derived for an average concentration which includes spatial and temporal correlations induced by the fluctuating velocity fields assumed to be Gaussianly distributed. The resulting equation becomes nonlocal, and if correlations between different components of the velocity field exist, it is also anisotropic. The simple limiting case of short correlation times is discussed and an effective diffusivity is obtained which reflects the enhanced mixing caused by the velocity fields. The results obtained in the limit of short correlation times are valid even if the probability distribution of the velocity field is not Gaussian.

  19. Effect of A-Site Cation Ordering on Chemical Stability, Oxygen Stoichiometry and Electrical Conductivity in Layered LaBaCo2O5+δ Double Perovskite

    PubMed Central

    Bernuy-Lopez, Carlos; Høydalsvik, Kristin; Einarsrud, Mari-Ann; Grande, Tor

    2016-01-01

    The effect of the A-site cation ordering on the chemical stability, oxygen stoichiometry and electrical conductivity in layered LaBaCo2O5+δ double perovskite was studied as a function of temperature and partial pressure of oxygen. Tetragonal A-site cation ordered layered LaBaCo2O5+δ double perovskite was obtained by annealing cubic A-site cation disordered La0.5Ba0.5CoO3-δ perovskite at 1100 °C in N2. High temperature X-ray diffraction between room temperature (RT) and 800 °C revealed that LaBaCo2O5+δ remains tetragonal during heating in oxidizing atmosphere, but goes through two phase transitions in N2 and between 450 °C and 675 °C from tetragonal P4/mmm to orthorhombic Pmmm and back to P4/mmm due to oxygen vacancy ordering followed by disordering of the oxygen vacancies. An anisotropic chemical and thermal expansion of LaBaCo2O5+δ was demonstrated. La0.5Ba0.5CoO3-δ remained cubic at the studied temperature irrespective of partial pressure of oxygen. LaBaCo2O5+δ is metastable with respect to La0.5Ba0.5CoO3-δ at oxidizing conditions inferred from the thermal evolution of the oxygen deficiency and oxidation state of Co in the two materials. The oxidation state of Co is higher in La0.5Ba0.5CoO3-δ resulting in a higher electrical conductivity relative to LaBaCo2O5+δ. The conductivity in both materials was reduced with decreasing partial pressure of oxygen pointing to a p-type semiconducting behavior. PMID:28773279

  20. Magnet/Hall-Effect Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

    1991-01-01

    In proposed magnet/Hall-effect random-access memory (MHRAM), bits of data stored magnetically in Perm-alloy (or equivalent)-film memory elements and read out by using Hall-effect sensors to detect magnetization. Value of each bit represented by polarity of magnetization. Retains data for indefinite time or until data rewritten. Speed of Hall-effect sensors in MHRAM results in readout times of about 100 nanoseconds. Other characteristics include high immunity to ionizing radiation and storage densities of order 10(Sup6)bits/cm(Sup 2) or more.

  1. Random effects of fissile lumps in molten salt reactors

    SciTech Connect

    Dulla, S.; Ravetto, P.; Prinja, A. K.

    2013-07-01

    The problem of the effect of fissile lumps spatially appearing in a random fashion inside a fluid fuel reactor is addressed. The effect on reactivity is evaluated by means of first-order perturbation theory. The analysis is carried out in diffusion theory with the presence of delayed neutron emissions in one dimensional plane geometry. The estimation of the mean value and standard deviation of the reactivity inserted is performed by Monte Carlo simulations and a deterministic quadrature approach, to compare the methods in terms of computational effort and the accuracy of the results. The results presented show that the effects constitute an important issue in the assessment of these innovative systems. (authors)

  2. Magnet/Hall-Effect Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

    1991-01-01

    In proposed magnet/Hall-effect random-access memory (MHRAM), bits of data stored magnetically in Perm-alloy (or equivalent)-film memory elements and read out by using Hall-effect sensors to detect magnetization. Value of each bit represented by polarity of magnetization. Retains data for indefinite time or until data rewritten. Speed of Hall-effect sensors in MHRAM results in readout times of about 100 nanoseconds. Other characteristics include high immunity to ionizing radiation and storage densities of order 10(Sup6)bits/cm(Sup 2) or more.

  3. Effect of thermal noise on random lasers in diffusion regime

    NASA Astrophysics Data System (ADS)

    Zarei, Mohammad Ali; Hosseini-Farzad, Mahmood; Montakhab, Afshin

    2015-09-01

    In this paper, we study the effects of thermal noise on the time evolution of a weak light pulse (probe) in the presence of a strong light pulse (pump) within a gain medium which includes random scatterer particles. Suitable thermal noise term is added to a set of four coupled equations including three diffusion equations for energy densities and a rate equation for the upper level population in a four-level gain medium. These equations have been solved simultaneously by Crank-Nicholson numerical method. The main result is that the back-scattered output probe light is increased as the thermal noise strength is increased and simultaneously, with the same rate, the amplified spontaneous emission is decreased. Therefore, the amplified response of the random laser in diffusion regime for the input probe pulse is enhanced due to effect of the thermal noise.

  4. [Randomized controlled trials terminated prematurely: beneficial therapy effects].

    PubMed

    Kluth, L A; Rink, M; Ahyai, S A; Fisch, M; Shariat, S F; Dahm, P

    2013-08-01

    Randomized controlled trials (RCTs) stopped prematurely for beneficial therapy effects are becoming increasingly more prevalent in the urological literature and often receive great attention in the public and medical media. Urologists who practice evidence-based medicine should be aware of the potential bias and the different reasons why and how early termination of RCTs can and will affect the results. This review provides insights into the challenges clinical urologists face by interpreting the results of prematurely terminated RCTs.

  5. Radiation Effects of Commercial Resistive Random Access Memories

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; LaBel, Kenneth A.; Berg, Melanie; Wilcox, Edward; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Buchner, Stephen; Khachatrian, Ani; Roche, Nicolas

    2014-01-01

    We present results for the single-event effect response of commercial production-level resistive random access memories. We found that the resistive memory arrays are immune to heavy ion-induced upsets. However, the devices were susceptible to single-event functional interrupts, due to upsets from the control circuits. The intrinsic radiation tolerant nature of resistive memory makes the technology an attractive consideration for future space applications.

  6. Analyzing degradation data with a random effects spline regression model

    DOE PAGES

    Fugate, Michael Lynn; Hamada, Michael Scott; Weaver, Brian Phillip

    2017-03-17

    This study proposes using a random effects spline regression model to analyze degradation data. Spline regression avoids having to specify a parametric function for the true degradation of an item. A distribution for the spline regression coefficients captures the variation of the true degradation curves from item to item. We illustrate the proposed methodology with a real example using a Bayesian approach. The Bayesian approach allows prediction of degradation of a population over time and estimation of reliability is easy to perform.

  7. Randomization inference for treatment effects on a binary outcome.

    PubMed

    Rigdon, Joseph; Hudgens, Michael G

    2015-03-15

    Two methods are developed for constructing randomization-based confidence sets for the average effect of a treatment on a binary outcome. The methods are nonparametric and require no assumptions about random sampling from a larger population. Both of the resulting 1 - α confidence sets are exact in the sense that the probability of containing the true treatment effect is at least 1 - α. Both types of confidence sets are also guaranteed to have width no greater than one. In contrast, a previously proposed asymptotic confidence interval is not exact and may have width greater than 1. The first approach combines Bonferroni-adjusted prediction sets for the attributable effects in the treated and untreated. The second method entails inverting a permutation test. Simulations are presented comparing the two randomization-based confidence sets with the asymptotic interval as well as the standard Wald confidence interval and a commonly used exact interval for the difference in binomial proportions. Results show for small to moderate sample sizes that the permutation confidence set attains the narrowest width on average among the methods that maintain nominal coverage. Extensions that allow for stratifying on categorical baseline covariates are also discussed. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Effects of Check and Connect on Attendance, Behavior, and Academics: A Randomized Effectiveness Trial

    ERIC Educational Resources Information Center

    Maynard, Brandy R.; Kjellstrand, Elizabeth K.; Thompson, Aaron M.

    2014-01-01

    Objectives: This study examined the effects of Check & Connect (C&C) on the attendance, behavior, and academic outcomes of at-risk youth in a field-based effectiveness trial. Method: A multisite randomized block design was used, wherein 260 primarily Hispanic (89%) and economically disadvantaged (74%) students were randomized to treatment…

  9. Effects of Check and Connect on Attendance, Behavior, and Academics: A Randomized Effectiveness Trial

    ERIC Educational Resources Information Center

    Maynard, Brandy R.; Kjellstrand, Elizabeth K.; Thompson, Aaron M.

    2014-01-01

    Objectives: This study examined the effects of Check & Connect (C&C) on the attendance, behavior, and academic outcomes of at-risk youth in a field-based effectiveness trial. Method: A multisite randomized block design was used, wherein 260 primarily Hispanic (89%) and economically disadvantaged (74%) students were randomized to treatment…

  10. Effective Perron-Frobenius eigenvalue for a correlated random map.

    PubMed

    Pool, Roman R; Cáceres, Manuel O

    2010-09-01

    We investigate the evolution of random positive linear maps with various type of disorder by analytic perturbation and direct simulation. Our theoretical result indicates that the statistics of a random linear map can be successfully described for long time by the mean-value vector state. The growth rate can be characterized by an effective Perron-Frobenius eigenvalue that strongly depends on the type of correlation between the elements of the projection matrix. We apply this approach to an age-structured population dynamics model. We show that the asymptotic mean-value vector state characterizes the population growth rate when the age-structured model has random vital parameters. In this case our approach reveals the nontrivial dependence of the effective growth rate with cross correlations. The problem was reduced to the calculation of the smallest positive root of a secular polynomial, which can be obtained by perturbations in terms of Green's function diagrammatic technique built with noncommutative cumulants for arbitrary n -point correlations.

  11. Lasso adjustments of treatment effect estimates in randomized experiments

    PubMed Central

    Bloniarz, Adam; Liu, Hanzhong; Zhang, Cun-Hui; Sekhon, Jasjeet S.; Yu, Bin

    2016-01-01

    We provide a principled way for investigators to analyze randomized experiments when the number of covariates is large. Investigators often use linear multivariate regression to analyze randomized experiments instead of simply reporting the difference of means between treatment and control groups. Their aim is to reduce the variance of the estimated treatment effect by adjusting for covariates. If there are a large number of covariates relative to the number of observations, regression may perform poorly because of overfitting. In such cases, the least absolute shrinkage and selection operator (Lasso) may be helpful. We study the resulting Lasso-based treatment effect estimator under the Neyman–Rubin model of randomized experiments. We present theoretical conditions that guarantee that the estimator is more efficient than the simple difference-of-means estimator, and we provide a conservative estimator of the asymptotic variance, which can yield tighter confidence intervals than the difference-of-means estimator. Simulation and data examples show that Lasso-based adjustment can be advantageous even when the number of covariates is less than the number of observations. Specifically, a variant using Lasso for selection and ordinary least squares (OLS) for estimation performs particularly well, and it chooses a smoothing parameter based on combined performance of Lasso and OLS. PMID:27382153

  12. Effectiveness of adenotonsillectomy in PFAPA syndrome: a randomized study.

    PubMed

    Garavello, Werner; Romagnoli, Marco; Gaini, Renato Maria

    2009-08-01

    To evaluate whether adenotonsillectomy leads to complete resolution in children with PFAPA (periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis) syndrome. Thirty-nine children with PFAPA syndrome were randomized to either adenotonsillectomy (surgery group; n = 19) or expectant management (control group; n = 20). All patients were then invited prospectively to record all PFAPA episodes, and were evaluated clinically every 3 months for 18 months after randomization. The proportion of patients experiencing complete resolution was 63% in the surgery group and 5% in the control group (P < .001). The mean (+/- standard deviation) number of episodes recorded during the study period was 0.7 +/- 1.2 in the surgery group and 8.1 +/- 3.9 in the control group (P < .001). The episodes were less severe in the surgery group. Adenotonsillectomy is an effective treatment strategy for children with PFAPA syndrome.

  13. Effect of A-site cations on the broadband-sensitive upconversion of AZrO3:Er3+,Ni2+ (A = Ca, Sr, Ba) phosphors

    NASA Astrophysics Data System (ADS)

    Luitel, Hom Nath; Mizuno, Shintaro; Tani, Toshihiko; Takeda, Yasuhiko

    2017-02-01

    We investigated broadband-sensitive upconversion processes in a series of AZrO3 type perovskites codoped with Ni2+ and Er3+, especially giving focus on the effect of the A-site host cations viz. Ca, Sr, Ba. Absorption and Stokes emission of the Ni2+ changed remarkably according to the A-site cations making difference in the Ni2+ to Er3+ energy transfer efficiency. The energy transfer extent from the Ni2+ sensitizers to the Er3+ emitters and the back transfer from the Er3+ to the Ni2+ were studied to clarify the guide for efficient broadband-sensitive upconversion. The Ni2+ to Er3+ energy transfer efficiency and hence the Er3+ upconversion emission intensity was dependent on the extent of overlap between the Er3+ absorption and the Ni2+ emission bands. Larger the overlap, faster was the energy transfer from the Ni2+ to the Er3+, leading to more intense Er3+ upconversion emission. However, back energy transfer from the Er3+ to the Ni2+ due to significant overlap of the Er3+ emission band with the Ni2+ absorption band reduced the upconversion emission intensity. Another important factor is the upconversion efficiency of the Er3+ emitters themselves after the energy transfer from the Ni2+ sensitizers, which was significantly improved when the symmetry around the Er3+ was lowered. As a result of these combined effects, the CaZrO3 host exhibited the most intense Ni2+-sensitized upconversion emission compared to the Sr and Ba analogues. Thus, for the efficient broadband-sensitive upconversion to be realized, a low symmetry host to manifest efficient upconversion of the Er3+ emitters and controlled Ni2+ absorption and emission bands to suppress the back energy transfer while maintaining efficient energy transfer in the forward direction are essential.

  14. Effect of random charge fluctuation on strongly coupled dusty Plasma

    SciTech Connect

    Issaad, M.; Rouiguia, L.; Djebli, M.

    2008-09-07

    Modeling the interaction between particles is an open issue in dusty plasma. We dealt with strongly coupled dust particles in two dimensional confined system. For small number of clusters, we investigate the effect of random charge fluctuation on background configuration. The study is conducted for a short rang as well as a long rang potential interaction. Numerical simulation is performed using Monte-Carlo simulation in the presence of parabolic confinement and at low temperature. We have studied the background configurations for a dust particles with constant charge and in the presence of random charge fluctuation due to the discrete nature of charge carriers. The latter is studied for a positively charged dust when the dominant charging process is due to photo-emission from the dust surface. It is found, for small classical cluster consisting of small number of particles, short rang potential gives the same result as long rang one. It is also found that the random charge fluctuation affect the background configurations.

  15. The Effect of Random Edge Removal on Network Degree Sequence

    PubMed Central

    DuBois, Thomas; Eubank, Stephen; Srinivasan, Aravind

    2012-01-01

    Many networks arise in a random and distributed fashion, and yet result in having a specific type of degree structure: e.g., the WWW, many social networks, biological networks, etc., exhibit power-law, stretched exponential, or similar degree structures. Much work has examined how a graph’s degree-structure influences other graph properties such as connectivity, diameter, etc. Probabilistic edge removal models link failures, information spreading, and processes that consider (random) subgraphs. They also model spreading influence of information as in the independent cascade model [20]. We examine what happens to a graph’s degree structure under edge failures where the edges are removed independently with identical probabilities. We start by analyzing the effect of edge failure on the degree sequence for power-law and exponential networks, and improve upon results of Martin, Carr & Faulon and Cooper & Lu; then, using intuition from the power-law case, we derive asymptotic results for almost any degree sequence of interest. Our major result shows a classification of degree sequences which leads to simple rules that give much of the new expected degree sequence after random edge-removal; we also provide associated concentration bounds. PMID:23024579

  16. A-SITE-AND/OR B-SITE-MODIFIED PBZRTIO3 MATERIALS AND (PB, SR, CA, BA, MG) (ZR, TI,NB, TA)O3 FILMS HAVING UTILITY IN FERROELECTRIC RANDOM ACCESS MEMORIES AND HIGH PERFORMANCE THIN FILM MICROACTUATORS

    NASA Technical Reports Server (NTRS)

    Roeder, Jeffrey F. (Inventor); Chen, Ing-Shin (Inventor); Bilodeau, Steven (Inventor); Baum, Thomas H. (Inventor)

    2004-01-01

    A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

  17. Effective band structure of random III-V alloys

    NASA Astrophysics Data System (ADS)

    Popescu, Voicu; Zunger, Alex

    2010-03-01

    Random substitutional alloys have no long range order (LRO) or translational symmetry so rigorously speaking they have no E(k) band structure or manifestations thereof. Yet, many experiments on alloys are interpreted using the language of band theory, e.g. inferring Van Hove singularities, band dispersion and effective masses. Many standard alloy theories (VCA- or CPA-based) have the LRO imposed on the alloy Hamiltonian, assuming only on-site disorder, so they can not be used to judge the extent of LRO that really exists. We adopt the opposite way, by using large (thousand atom) randomly generated supercells in which chemically identical alloy atoms are allowed to have different local environments (a polymorphous representation). This then drives site-dependent atomic relaxation as well as potential fluctuations. The eigenstates from such supercells are then mapped onto the Brillouin zone (BZ) of the primitive cell, producing effective band dispersion. Results for (In,Ga)X show band-like behaviour only near the centre and faces of the BZ but rapidly lose such characteristics away from γ or for higher bands. We further analyse the effects of stoichiometry variation, internal relaxation, and short-range order on the alloy band structure.

  18. Random-effects models for serial observations with binary response

    SciTech Connect

    Stiratelli, R.; Laird, N.; Ware, J.H.

    1984-12-01

    This paper presents a general mixed model for the analysis of serial dichotomous responses provided by a panel of study participants. Each subject's serial responses are assumed to arise from a logistic model, but with regression coefficients that vary between subjects. The logistic regression parameters are assumed to be normally distributed in the population. Inference is based upon maximum likelihood estimation of fixed effects and variance components, and empirical Bayes estimation of random effects. Exact solutions are analytically and computationally infeasible, but an approximation based on the mode of the posterior distribution of the random parameters is proposed, and is implemented by means of the EM algorithm. This approximate method is compared with a simpler two-step method proposed by Korn and Whittemore, using data from a panel study of asthmatics originally described in that paper. One advantage of the estimation strategy described here is the ability to use all of the data, including that from subjects with insufficient data to permit fitting of a separate logistic regression model, as required by the Korn and Whittemore method. However, the new method is computationally intensive.

  19. Effect of overpasses in the Biham-Middleton-Levine traffic flow model with random and parallel update rule.

    PubMed

    Ding, Zhong-Jun; Jiang, Rui; Gao, Zi-You; Wang, Bing-Hong; Long, Jiancheng

    2013-08-01

    The effect of overpasses in the Biham-Middleton-Levine traffic flow model with random and parallel update rules has been studied. An overpass is a site that can be occupied simultaneously by an eastbound car and a northbound one. Under periodic boundary conditions, both self-organized and random patterns are observed in the free-flowing phase of the parallel update model, while only the random pattern is observed in the random update model. We have developed mean-field analysis for the moving phase of the random update model, which agrees with the simulation results well. An intermediate phase is observed in which some cars could pass through the jamming cluster due to the existence of free paths in the random update model. Two intermediate states are observed in the parallel update model, which have been ignored in previous studies. The intermediate phases in which the jamming skeleton is only oriented along the diagonal line in both models have been analyzed, with the analyses agreeing well with the simulation results. With the increase of overpass ratio, the jamming phase and the intermediate phases disappear in succession for both models. Under open boundary conditions, the system exhibits only two phases when the ratio of overpasses is below a threshold in the random update model. When the ratio of the overpass is close to 1, three phases could be observed, similar to the totally asymmetric simple exclusion process model. The dependence of the average velocity, the density, and the flow rate on the injection probability in the moving phase has also been obtained through mean-field analysis. The results of the parallel model under open boundary conditions are similar to that of the random update model.

  20. Mixed-Effects Modeling with Crossed Random Effects for Subjects and Items

    ERIC Educational Resources Information Center

    Baayen, R. H.; Davidson, D. J.; Bates, D. M.

    2008-01-01

    This paper provides an introduction to mixed-effects models for the analysis of repeated measurement data with subjects and items as crossed random effects. A worked-out example of how to use recent software for mixed-effects modeling is provided. Simulation studies illustrate the advantages offered by mixed-effects analyses compared to…

  1. A mediator effect size in randomized clinical trials.

    PubMed

    Kraemer, Helena Chmura

    2014-12-01

    To understand the process by which a treatment (T) achieves an effect on outcome (O) and thus to improve the effect of T on O, it is vital to detect mediators, to compare the impact of different mediators, and to develop hypotheses about the causal factors (all mediators) linking T and O. An index is needed to facilitate interpretation of the potential clinical importance of a mediator (M) of choice of T on treatment O in randomized clinical trials (RCTs). Ideally such a mediator effect size should (1) be invariant under any rescaling of M and O consistent with the model used, and (2) reflect the difference between the overall observed effect of T on O and what the maximal effect of T on O could be were the association between T and M broken. A mediator effect size is derived first for the traditional linear model, and then more generally for any categorical (ordered or non-ordered) potential mediator. Issues such as the problem of multiple treatments, outcomes and mediators, and of causal inferences, and the correspondence between this approach and earlier ones, are discussed. Illustrations are given of the application of the approach. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Effects of reciprocity on random walks in weighted networks.

    PubMed

    Zhang, Zhongzhi; Li, Huan; Sheng, Yibin

    2014-12-12

    It has been recently reported that the reciprocity of real-life weighted networks is very pronounced, however its impact on dynamical processes is poorly understood. In this paper, we study random walks in a scale-free directed weighted network with a trap at the central hub node, where the weight of each directed edge is dominated by a parameter controlling the extent of network reciprocity. We derive two expressions for the mean first passage time (MFPT) to the trap, by using two different techniques, the results of which agree well with each other. We also analytically determine all the eigenvalues as well as their multiplicities for the fundamental matrix of the dynamical process, and show that the largest eigenvalue has an identical dominant scaling as that of the MFPT.We find that the weight parameter has a substantial effect on the MFPT, which behaves as a power-law function of the system size with the power exponent dependent on the parameter, signaling the crucial role of reciprocity in random walks occurring in weighted networks.

  3. Effect of Random Clustering on Surface Damage Density Estimates

    SciTech Connect

    Matthews, M J; Feit, M D

    2007-10-29

    Identification and spatial registration of laser-induced damage relative to incident fluence profiles is often required to characterize the damage properties of laser optics near damage threshold. Of particular interest in inertial confinement laser systems are large aperture beam damage tests (>1cm{sup 2}) where the number of initiated damage sites for {phi}>14J/cm{sup 2} can approach 10{sup 5}-10{sup 6}, requiring automatic microscopy counting to locate and register individual damage sites. However, as was shown for the case of bacteria counting in biology decades ago, random overlapping or 'clumping' prevents accurate counting of Poisson-distributed objects at high densities, and must be accounted for if the underlying statistics are to be understood. In this work we analyze the effect of random clumping on damage initiation density estimates at fluences above damage threshold. The parameter {psi} = a{rho} = {rho}/{rho}{sub 0}, where a = 1/{rho}{sub 0} is the mean damage site area and {rho} is the mean number density, is used to characterize the onset of clumping, and approximations based on a simple model are used to derive an expression for clumped damage density vs. fluence and damage site size. The influence of the uncorrected {rho} vs. {phi} curve on damage initiation probability predictions is also discussed.

  4. Effects of reciprocity on random walks in weighted networks

    PubMed Central

    Zhang, Zhongzhi; Li, Huan; Sheng, Yibin

    2014-01-01

    It has been recently reported that the reciprocity of real-life weighted networks is very pronounced, however its impact on dynamical processes is poorly understood. In this paper, we study random walks in a scale-free directed weighted network with a trap at the central hub node, where the weight of each directed edge is dominated by a parameter controlling the extent of network reciprocity. We derive two expressions for the mean first passage time (MFPT) to the trap, by using two different techniques, the results of which agree well with each other. We also analytically determine all the eigenvalues as well as their multiplicities for the fundamental matrix of the dynamical process, and show that the largest eigenvalue has an identical dominant scaling as that of the MFPT.We find that the weight parameter has a substantial effect on the MFPT, which behaves as a power-law function of the system size with the power exponent dependent on the parameter, signaling the crucial role of reciprocity in random walks occurring in weighted networks. PMID:25500907

  5. The Effectiveness of Propolis on Gingivitis: A Randomized Controlled Trial

    PubMed Central

    Paulino, Niraldo; Nör, Jacques E.; Moreira, Alexandre

    2014-01-01

    Abstract Background: A randomized, double-blind, controlled clinical trial was conducted to evaluate the effectiveness of a propolis rinse on induced gingivitis by using the co-twin study design. Methods: Twenty-one twin pairs (n=42) were enrolled in a gingivitis study with oral hygiene promotion (14 days) and gingivitis induction (21 days). During the gingivitis induction phase, one member of the twin pair was randomly assigned to a 2% typified propolis rinse, and the other was assigned a color-matched 0.05% sodium fluoride plus 0.05% cetylpyridinium chloride rinse (positive control). Patients rinsed twice daily with 20 mL for 30 seconds for 21 days. Gingivitis was measured on days −14 (baseline), 0 (after hygiene phase), and 21 (after no-hygiene phase) by using the Papillary Bleeding Score (PBS) and by standard digital imaging of the gum tissues (G-parameter). Results: The 38 persons who completed the study (age 13–22 years) were well balanced according to PBS at baseline and G-parameter after the initial hygiene phase. After 21 days without oral hygiene, the propolis rinse and positive control rinse groups did not differ significantly for average PBS measurements or G-parameter. Conclusions: Use of a 2% typified propolis rinse was equivalent to a positive control rinse during a 21-day no-hygiene period. PMID:25380344

  6. The effectiveness of propolis on gingivitis: a randomized controlled trial.

    PubMed

    Bretz, Walter A; Paulino, Niraldo; Nör, Jacques E; Moreira, Alexandre

    2014-12-01

    A randomized, double-blind, controlled clinical trial was conducted to evaluate the effectiveness of a propolis rinse on induced gingivitis by using the co-twin study design. Twenty-one twin pairs (n=42) were enrolled in a gingivitis study with oral hygiene promotion (14 days) and gingivitis induction (21 days). During the gingivitis induction phase, one member of the twin pair was randomly assigned to a 2% typified propolis rinse, and the other was assigned a color-matched 0.05% sodium fluoride plus 0.05% cetylpyridinium chloride rinse (positive control). Patients rinsed twice daily with 20 mL for 30 seconds for 21 days. Gingivitis was measured on days -14 (baseline), 0 (after hygiene phase), and 21 (after no-hygiene phase) by using the Papillary Bleeding Score (PBS) and by standard digital imaging of the gum tissues (G-parameter). The 38 persons who completed the study (age 13-22 years) were well balanced according to PBS at baseline and G-parameter after the initial hygiene phase. After 21 days without oral hygiene, the propolis rinse and positive control rinse groups did not differ significantly for average PBS measurements or G-parameter. Use of a 2% typified propolis rinse was equivalent to a positive control rinse during a 21-day no-hygiene period.

  7. Random copolymers at a selective interface: saturation effects.

    PubMed

    Kłos, J; Sommer, J-U

    2007-11-07

    Combining scaling arguments and Monte Carlo simulations using the bond fluctuation method we have studied concentration effects for the adsorption of symmetric AB-random copolymers at selective, symmetric interfaces. For the scaling analysis we consider a hierarchy of two length scales given by the excess (adsorption) blobs and by two dimensional thermal blobs in the semidilute surface regime. When both length scales match, a densely packed array of adsorption blobs is formed (saturation). We show that for random copolymer adsorption the interface concentration can be further increased (oversaturation) due to reorganization of excess blobs. Crossing over this threshold results in a qualitative change in the behavior of the adsorption layer which involves a change in the average shape of the adsorbed chains towards a hairpinlike form. We have analyzed the distribution of loops and tails of adsorbed chains in the various concentration regimes as well as the chain order parameter, concentration profiles, and the exchange rate of individual chains. We emphasized the role of saturation scaling which dominates the behavior of static and dynamic quantities at higher surface concentration.

  8. Vasopressin Boosts Placebo Analgesic Effects in Women: A Randomized Trial

    PubMed Central

    Colloca, Luana; Pine, Daniel S.; Ernst, Monique; Miller, Franklin G.; Grillon, Christian

    2015-01-01

    Background Social cues and interpersonal interactions strongly contribute to evoke placebo effects that are pervasive in medicine and depend upon the activation of endogenous modulatory systems. Here we explore the possibility to boost placebo effects by targeting pharmacologically the vasopressin system, characterized by a sexually dimorphic response and involved in the regulation of human and nonhuman social behaviors. Methods We enrolled 109 healthy participants and studied the effects of intranasal administration of Avp1a and Avp1b arginine vasopressin receptor agonists against 1) no-treatment, 2) oxytocin, and 3) saline, in a randomized, placebo-controlled, double-blind, parallel design trial using a well-established model of placebo analgesia while controlling for sex differences. Results Vasopressin agonists boosted placebo effects in women but had no effect in men. The effects of vasopressin on expectancy-induced analgesia were significantly larger than those observed in the no-treatment (p<004), oxytocin (p<0.001) and saline (p<0.015) groups. Moreover, women with lower dispositional anxiety and cortisol levels showed the largest vasopressin-induced modulation of placebo effects, suggesting a moderating interplay between pre-existing psychological factors and cortisol changes. Conclusions This is the first study that demonstrates that arginine vasopressin boosts placebo effects and that the effect of vasopressin depends upon a significant sex by treatment interaction. These findings are novel and might open up new avenues for clinically relevant research due to the therapeutic potentials of vasopressin and oxytocin as well as the possibility to systematically control for influences of placebo responses in clinical trials. PMID:26321018

  9. Static and dynamic optical properties of La1-xSrxFeO3-δ: The effects of A-site and oxygen stoichiometry

    DOE PAGES

    Sergey Y. Smolin; Sfeir, Matthew Y.; Scafetta, Mark D.; ...

    2015-12-09

    Perovskite oxides are a promising material class for photovoltaic and photocatalytic applications due to their visible band gaps, nanosecond recombination lifetimes, and great chemical diversity. However, there is limited understanding of the link between composition and static and dynamic optical properties, despite the critical role these properties play in the design of light-harvesting devices. To clarify these relationships, we systemically studied the optoelectronic properties in La1-xSrxFeO3-δ epitaxial films, uncovering the effects of A-site cation substitution and oxygen stoichiometry. Variable-angle spectroscopic ellipsometry was used to measure static optical properties, revealing a linear increase in absorption coefficient at 1.25 eV and amore » red-shifting of the optical absorption edge with increasing Sr fraction. The absorption spectra can be similarly tuned through the introduction of oxygen vacancies, indicating the critical role that nominal Fe valence plays in optical absorption. Dynamic optoelectronic properties were studied with ultrafast transient reflectance spectroscopy, revealing similar nanosecond photoexcited carrier lifetimes for oxygen deficient and stoichiometric films with the same nominal Fe valence. Furthermore, these results demonstrate that while the static optical absorption is strongly dependent on nominal Fe valence tuned through cation or anion stoichiometry, oxygen vacancies do not appear to play a significantly detrimental role in the recombination kinetics.« less

  10. Effect of packing method on the randomness of disc packings

    NASA Astrophysics Data System (ADS)

    Zhang, Z. P.; Yu, A. B.; Oakeshott, R. B. S.

    1996-06-01

    The randomness of disc packings, generated by random sequential adsorption (RSA), random packing under gravity (RPG) and Mason packing (MP) which gives a packing density close to that of the RSA packing, has been analysed, based on the Delaunay tessellation, and is evaluated at two levels, i.e. the randomness at individual subunit level which relates to the construction of a triangle from a given edge length distribution and the randomness at network level which relates to the connection between triangles from a given triangle frequency distribution. The Delaunay tessellation itself is also analysed and its almost perfect randomness at the two levels is demonstrated, which verifies the proposed approach and provides a random reference system for the present analysis. It is found that (i) the construction of a triangle subunit is not random for the RSA, MP and RPG packings, with the degree of randomness decreasing from the RSA to MP and then to RPG packing; (ii) the connection of triangular subunits in the network is almost perfectly random for the RSA packing, acceptable for the MP packing and not good for the RPG packing. Packing method is an important factor governing the randomness of disc packings.

  11. Effective dynamic constitutive parameters of acoustic metamaterials with random microstructure

    NASA Astrophysics Data System (ADS)

    Caleap, Mihai; Drinkwater, Bruce W.; Wilcox, Paul D.

    2012-03-01

    A multiple scattering analysis in a non-viscous fluid is developed in order to predict the effective constitutive parameters of certain suspensions of disordered particles or bubbles. The analysis is based on an effective field approach, and uses suitable pair-correlation functions to account for the essential features of densely distributed particles. The effective medium that is equivalent to the original suspension of particles is a medium with space and time dispersion, and hence, its parameters are functions of the frequency of the incident acoustic wave. Under the quasi-crystalline approximation, novel expressions are presented for effective constitutive parameters, which are valid at any frequency and wavelength. The emerging possibility of designing fluid-particle mixtures to form acoustic metamaterials is discussed. Our theory provides a convenient tool for testing ideas in silico in the search for new metamaterials with specific desired properties. An important conclusion of the proposed approach is that negative constitutive parameters can also be achieved by using suspensions of particles with random microstructures with properties similar to those shown in periodic arrays of microstructures.

  12. Experimental studies of random-field effects in uniaxial random antiferromagnets

    SciTech Connect

    Wong, P.Z.; Cable, J.W.; von Molnar, S.; Dimon, P.

    1983-11-01

    We discuss how random fields (RFs) are generated in uniaxial random antiferromagnets (URAFs) by applied fields and review the experiments that have been performed on these systems. They include direct and indirect specific heat measurements, neutron scattering experiments and phase diagram studies. We compare the results of different experiments on different systems, discuss their implications on the theories, and suggest further experiments. A new explanation for the Lorentzian-squared (LSQ) structure factor observed in the neutron scattering experiments is also given. 47 references, 4 figures.

  13. Auditory model: effects on learning under blocked and random practice schedules.

    PubMed

    Han, Dong-Wook; Shea, Charles H

    2008-12-01

    An experiment was conducted to determine the impact of an auditory model on blocked, random, and mixed practice schedules of three five-segment timing sequences (relative time constant). We were interested in whether or not the auditory model differentially affected the learning of relative and absolute timing under blocked and random practice. Participants (N = 80) were randomly assigned to one of eight practice conditions, which differed in practice schedule (blocked-blocked, blocked-random, random-blocked, random-random) and auditory model (no model, model). The results indicated that the auditory model enhanced relative timing performance on the delayed retention test regardless of the practice schedule, but it did not influence the learning of absolute timing. Blocked-blocked and blocked-random practice conditions resulted in enhanced relative timing retention performance relative to random-blocked and random-random practice schedules. Random-random and blocked-random practice schedules resulted in better absolute timing than blocked-blocked or random-blocked practice, regardless of the presence or absence of an auditory model during acquisition. Thus, considering both relative and absolute timing, the blocked-random practice condition resulted in overall learning superior to the other practice schedules. The results also suggest that an auditory model produces an added effect on learning relative timing regardless of the practice schedule, but it does not influence the learning of absolute timing.

  14. Placebo Effects and the Common Cold: A Randomized Controlled Trial

    PubMed Central

    Barrett, Bruce; Brown, Roger; Rakel, Dave; Rabago, David; Marchand, Lucille; Scheder, Jo; Mundt, Marlon; Thomas, Gay; Barlow, Shari

    2011-01-01

    blinded to echinacea, and 70 pg/mL and 1 cell for the group with open-label echinacea, also not statistically significant. Among the 120 participants who at intake rated echinacea’s effectiveness as greater than 50 on a 100-point scale for which 100 is extremely effective, illness duration was 2.58 days shorter (95% CI, −4.47 to −0.68 days) in those blinded to placebo rather than no pill, and mean global severity score was 26% lower but not significantly different (−97.0, 95% CI, −249.8 to 55.8 points). In this subgroup, neither duration nor severity differed significantly between the group blinded to echinacea and the open-label echinacea group. CONCLUSIONS Participants randomized to the no-pill group tended to have longer and more severe illnesses than those who received pills. For the subgroup who believed in echinacea and received pills, illnesses were substantively shorter and less severe, regardless of whether the pills contained echinacea. These findings support the general idea that beliefs and feelings about treatments may be important and perhaps should be taken into consideration when making medical decisions. PMID:21747102

  15. Randomized perturbed posturography: methodology and effects of midazolam sedation.

    PubMed

    Ledin, T; Gupta, A; Larsen, L E; Odkvist, L M

    1993-05-01

    To study quiescent stance without applying external disturbances is not a theoretically appealing way to unveil the dynamic properties of human equilibrium. Methods to disturb equilibrium range from standing on foam surface, attaching vibrators to the calves to interfere with somatosensation, and exposure to body-position tracking environments, as in dynamic posturography (EquiTest). The EquiTest apparatus was modified by a menu-driven software to allow arbitrary movements of the support surface and visual surround, and force data were recorded for subsequent analysis. The support surface was randomly moved in the antero-posterior direction. First equilibrium was studied on the stable support surface, then low (RMS 1.3 cm) and high (RMS 2.6 cm) amplitude movements were used. Vision was either present or absent at all test amplitudes. Equilibrium was evaluated by the confidence (61%) ellipse sway area and average sway velocity during 45 s. Eleven healthy subjects aged 23-36 years (mean 29) were sedated with a short acting sedative, midazolam 0.1 mg/kg. Randomized perturbed posturography was conducted at baseline, and at about 60, 120 and 180 min after injection. Psychomotor tests were conducted at baseline, and at 30, 90, 150 and 210 min. Large interindividual variations were found. One subject could not be tested at all at 60 min due to sleepiness, whereas some subjects felt nearly full awake at 30 min. Sway areas were larger at 60 min, but not subsequently. At 60 min, sway velocities with open eyes were higher, just as when vision was absent and low amplitude movements were used. Later no effects could be shown.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Worksite intervention effects on physical health: a randomized controlled trial.

    PubMed

    Atlantis, Evan; Chow, Chin-Moi; Kirby, Adrienne; Fiatarone Singh, Maria A

    2006-09-01

    Overweight and physical inactivity are risk factors for increased disease burden and health care expenditure. Well-designed studies are still needed to determine the treatment efficacy of worksite interventions targeting such risk factors. This randomized controlled trial was conducted at one of Australia's casinos in 2002-2003, to investigate the effects of a comprehensive exercise and lifestyle intervention on physical fitness. Only 6.4% of the workforce expressed interest in being study participants. Seventy-three employees (aged 32 +/- 8 years, 51% overweight/obese, 73% shift workers and 52% women) were recruited and randomized to treatment or wait-list control groups for 24 weeks, 44 of whom completed the intervention. Components of the intervention include supervised moderate-to-high intensity exercise including combined aerobic (at least 20 min duration 3 days/week) and weight-training (for an estimated 30 min completed 2-3 days/week), and dietary/health education (delivered via group seminars, one-on-one counselling and literature through the provision of a worksite manual). ANCOVA, by intention-to-treat and of study completers, found significant between-group differences in the mean waist circumference and predicted maximal oxygen uptake (VO2max), favouring the intervention, but effects were concentrated in one subject. For study completers, between-group differences in the mean waist circumference (82.3 +/- 9.2 versus 90.5 +/- 17.8 cm, p = 0.01) and predicted VO2max (47 versus 41 ml/kg/min, p < 0.001) remained significant without the outlier, favouring the intervention. Higher intervention compliance predicted greater improvements in physical fitness. No significant effects on body mass or body mass index were found. This worksite intervention significantly improved waist circumference and aerobic fitness in healthy but sedentary employees, most of whom were shift workers. Worksite interventions have the potential to counter the increasing burden of

  17. Effects of calcitriol on random skin flap survival in rats

    PubMed Central

    Zhou, Kai-liang; Zhang, Yi-hui; Lin, Ding-sheng; Tao, Xian-yao; Xu, Hua-zi

    2016-01-01

    Calcitriol, a metabolite of vitamin D, is often used in osteoporosis clinics. However, the material has other bioactivities; for example, it accelerates angiogenesis, has anti-inflammatory properties, and inhibits oxidative stress. We investigated the effects of calcitriol in a random skin flap rat model. “McFarlane flap” models were established in 84 male Sprague Dawley rats, divided into two groups. One group received intraperitoneal injections of calcitriol (2 μg/kg/day) whereas control rats received intraperitoneal injections of saline. The percentage flap survival area and tissue water content were measured 7 days later, which showed that calcitriol improved flap survival area and reduced tissue edema. It also increased the mean vessel density and upregulated levels of VEGF mRNA/protein, both of which promote flap angiogenesis. Moreover, it decreased leukocyte and macrophage infiltration, reduced the inflammatory proteins IL1β and IL6, increased SOD activity, decreased MDA content, and upregulated the level of autophagy. Overall, our results suggest that calcitriol promotes skin flap survival by accelerating angiogenesis, having anti-inflammatory effects, reducing oxidative stress, and promoting autophagy. PMID:26732750

  18. An effective Hamiltonian approach to quantum random walk

    NASA Astrophysics Data System (ADS)

    Sarkar, Debajyoti; Paul, Niladri; Bhattacharya, Kaushik; Ghosh, Tarun Kanti

    2017-03-01

    In this article we present an effective Hamiltonian approach for discrete time quantum random walk. A form of the Hamiltonian for one-dimensional quantum walk has been prescribed, utilizing the fact that Hamiltonians are generators of time translations. Then an attempt has been made to generalize the techniques to higher dimensions. We find that the Hamiltonian can be written as the sum of a Weyl Hamiltonian and a Dirac comb potential. The time evolution operator obtained from this prescribed Hamiltonian is in complete agreement with that of the standard approach. But in higher dimension we find that the time evolution operator is additive, instead of being multiplicative (see Chandrashekar, Sci. Rep. 3, 2829 (18)). We showed that in the case of two-step walk, the time evolution operator effectively can have multiplicative form. In the case of a square lattice, quantum walk has been studied computationally for different coins and the results for both the additive and the multiplicative approaches have been compared. Using the graphene Hamiltonian, the walk has been studied on a graphene lattice and we conclude the preference of additive approach over the multiplicative one.

  19. Random effects specifications in eigenvector spatial filtering: a simulation study

    NASA Astrophysics Data System (ADS)

    Murakami, Daisuke; Griffith, Daniel A.

    2015-10-01

    Eigenvector spatial filtering (ESF) is becoming a popular way to address spatial dependence. Recently, a random effects specification of ESF (RE-ESF) is receiving considerable attention because of its usefulness for spatial dependence analysis considering spatial confounding. The objective of this study was to analyze theoretical properties of RE-ESF and extend it to overcome some of its disadvantages. We first compare the properties of RE-ESF and ESF with geostatistical and spatial econometric models. There, we suggest two major disadvantages of RE-ESF: it is specific to its selected spatial connectivity structure, and while the current form of RE-ESF eliminates the spatial dependence component confounding with explanatory variables to stabilize the parameter estimation, the elimination can yield biased estimates. RE-ESF is extended to cope with these two problems. A computationally efficient residual maximum likelihood estimation is developed for the extended model. Effectiveness of the extended RE-ESF is examined by a comparative Monte Carlo simulation. The main findings of this simulation are as follows: Our extension successfully reduces errors in parameter estimates; in many cases, parameter estimates of our RE-ESF are more accurate than other ESF models; the elimination of the spatial component confounding with explanatory variables results in biased parameter estimates; efficiency of an accuracy maximization-based conventional ESF is comparable to RE-ESF in many cases.

  20. Random Walks and Effective Optical Depth in Relativistic Flow

    NASA Astrophysics Data System (ADS)

    Shibata, Sanshiro; Tominaga, Nozomu; Tanaka, Masaomi

    2014-05-01

    We investigate the random walk process in relativistic flow. In the relativistic flow, photon propagation is concentrated in the direction of the flow velocity due to the relativistic beaming effect. We show that in the pure scattering case, the number of scatterings is proportional to the size parameter ξ ≡ L/l 0 if the flow velocity β ≡ v/c satisfies β/Γ Gt ξ-1, while it is proportional to ξ2 if β/Γ Lt ξ-1, where L and l 0 are the size of the system in the observer frame and the mean free path in the comoving frame, respectively. We also examine the photon propagation in the scattering and absorptive medium. We find that if the optical depth for absorption τa is considerably smaller than the optical depth for scattering τs (τa/τs Lt 1) and the flow velocity satisfies \\beta \\gg \\sqrt{2\\tau _a/\\tau _s}, then the effective optical depth is approximated by τ* ~= τa(1 + β)/β. Furthermore, we perform Monte Carlo simulations of radiative transfer and compare the results with the analytic expression for the number of scatterings. The analytic expression is consistent with the results of the numerical simulations. The expression derived in this study can be used to estimate the photon production site in relativistic phenomena, e.g., gamma-ray burst and active galactic nuclei.

  1. The Effectiveness of Mandatory-Random Student Drug Testing

    ERIC Educational Resources Information Center

    James-Burdumy, Susanne; Goesling, Brian; Deke, John; Einspruch, Eric

    2011-01-01

    One approach some U.S. schools now use to combat high rates of adolescent substance use is school-based mandatory-random student drug testing (MRSDT). Under MRSDT, students and their parents sign consent forms agreeing to the students' participation in random drug testing as a condition of participating in athletics and other school-sponsored…

  2. A Study of Head Start Effectiveness Using a Randomized Design.

    ERIC Educational Resources Information Center

    Abbott-Shim, Martha; Lambert, Richard; McCart, Frances

    Although an extensive body of literature exists on the impact of Head Start, very few studies have used an experimental design with random assignment, a key methodological component needed to increase the weight of evaluation findings. This study used a randomized design with a wide range of outcomes related to school readiness to assess the…

  3. Plan a Site Visit with Your Legislator

    ERIC Educational Resources Information Center

    Ochs, Mike

    2005-01-01

    When members of Congress head home for a recess, participants in the grassroots network have an opportunity to use one of their effective education tools: the site visit. A site visit occurs when a legislator actually visits one's business, school, or organization to see one's work firsthand. A local site visit is effective because grassroots…

  4. Effective messages in vaccine promotion: a randomized trial.

    PubMed

    Nyhan, Brendan; Reifler, Jason; Richey, Sean; Freed, Gary L

    2014-04-01

    To test the effectiveness of messages designed to reduce vaccine misperceptions and increase vaccination rates for measles-mumps-rubella (MMR). A Web-based nationally representative 2-wave survey experiment was conducted with 1759 parents age 18 years and older residing in the United States who have children in their household age 17 years or younger (conducted June-July 2011). Parents were randomly assigned to receive 1 of 4 interventions: (1) information explaining the lack of evidence that MMR causes autism from the Centers for Disease Control and Prevention; (2) textual information about the dangers of the diseases prevented by MMR from the Vaccine Information Statement; (3) images of children who have diseases prevented by the MMR vaccine; (4) a dramatic narrative about an infant who almost died of measles from a Centers for Disease Control and Prevention fact sheet; or to a control group. None of the interventions increased parental intent to vaccinate a future child. Refuting claims of an MMR/autism link successfully reduced misperceptions that vaccines cause autism but nonetheless decreased intent to vaccinate among parents who had the least favorable vaccine attitudes. In addition, images of sick children increased expressed belief in a vaccine/autism link and a dramatic narrative about an infant in danger increased self-reported belief in serious vaccine side effects. Current public health communications about vaccines may not be effective. For some parents, they may actually increase misperceptions or reduce vaccination intention. Attempts to increase concerns about communicable diseases or correct false claims about vaccines may be especially likely to be counterproductive. More study of pro-vaccine messaging is needed.

  5. Effects of nattokinase on blood pressure: a randomized, controlled trial.

    PubMed

    Kim, Ji Young; Gum, Si Nae; Paik, Jean Kyung; Lim, Hyo Hee; Kim, Kyong-Chol; Ogasawara, Kazuya; Inoue, Kenichi; Park, Sungha; Jang, Yangsoo; Lee, Jong Ho

    2008-08-01

    The objective of this study was to examine the effects of nattokinase supplementation on blood pressure in subjects with pre-hypertension or stage 1 hypertension. In a randomized, double-blind, placebo-controlled trial, 86 participants ranging from 20 to 80 years of age with an initial untreated systolic blood pressure (SBP) of 130 to 159 mmHg received nattokinase (2,000 FU/capsule) or a placebo capsule for 8 weeks. Seventy-three subjects completed the protocol. Compared with the control group, the net changes in SBP and diastolic blood pressure (DBP) were -5.55 mmHg (95% confidence interval [CI], -10.5 to -0.57 mmHg; p<0.05) and -2.84 mmHg (CI, -5.33 to -0.33 mmHg; p<0.05), respectively, after the 8-week intervention. The corresponding net change in renin activity was -1.17 ng/mL/h for the nattokinase group compared with the control group (p<0.05). In conclusion, nattokinase supplementation resulted in a reduction in SBP and DBP. These findings suggest that increased intake of nattokinase may play an important role in preventing and treating hypertension.

  6. Sequential methods for random-effects meta-analysis

    PubMed Central

    Higgins, Julian P T; Whitehead, Anne; Simmonds, Mark

    2011-01-01

    Although meta-analyses are typically viewed as retrospective activities, they are increasingly being applied prospectively to provide up-to-date evidence on specific research questions. When meta-analyses are updated account should be taken of the possibility of false-positive findings due to repeated significance tests. We discuss the use of sequential methods for meta-analyses that incorporate random effects to allow for heterogeneity across studies. We propose a method that uses an approximate semi-Bayes procedure to update evidence on the among-study variance, starting with an informative prior distribution that might be based on findings from previous meta-analyses. We compare our methods with other approaches, including the traditional method of cumulative meta-analysis, in a simulation study and observe that it has Type I and Type II error rates close to the nominal level. We illustrate the method using an example in the treatment of bleeding peptic ulcers. Copyright © 2010 John Wiley & Sons, Ltd. PMID:21472757

  7. Effects of trimetazidine in nonischemic heart failure: a randomized study.

    PubMed

    Winter, José Luis; Castro, Pablo F; Quintana, Juan Carlos; Altamirano, Rodrigo; Enriquez, Andres; Verdejo, Hugo E; Jalil, Jorge E; Mellado, Rosemarie; Concepción, Roberto; Sepúlveda, Pablo; Rossel, Victor; Sepúlveda, Luis; Chiong, Mario; García, Lorena; Lavandero, Sergio

    2014-03-01

    Heart failure (HF) is associated with changes in myocardial metabolism that lead to impairment of contractile function. Trimetazidine (TMZ) modulates cardiac energetic efficiency and improves outcomes in ischemic heart disease. We evaluated the effects of TMZ on left ventricular ejection fraction (LVEF), cardiac metabolism, exercise capacity, O2 uptake, and quality of life in patients with nonischemic HF. Sixty patients with stable nonischemic HF under optimal medical therapy were included in this randomized double-blind study. Patients were randomized to TMZ (35 mg orally twice a day) or placebo for 6 months. LVEF, 6-minute walk test (6MWT), maximum O2 uptake in cardiopulmonary exercise test, different markers of metabolism, oxidative stress, and endothelial function, and quality of life were assessed at baseline and after TMZ treatment. Left ventricular peak glucose uptake was evaluated with the use of the maximum standardized uptake value (SUV) by 18-fluorodeoxyglucose positron emission tomography ((18)FDG-PET). Etiology was idiopathic in 85% and hypertensive in 15%. Both groups were similar in age, functional class, LVEF, and levels of N-terminal pro-B-type natriuretic peptide at baseline. After 6 months of TMZ treatment, no changes were observed in LVEF (31 ± 10% vs 34 ± 8%; P = .8), 6MWT (443 ± 25 m vs 506 ± 79 m; P = .03), maximum O2 uptake (19.1 ± 5.0 mL kg(-1) min(-1) vs 23.0 ± 7.2 mL kg(-1) min(-1); P = .11), functional class (percentages of patients in functional classes I/II/III/IV 10/3753/0 vs 7/40/50/3; P = .14), or quality of life (32 ± 26 points vs 24 ± 18 points; P = .25) in TMZ versus placebo, respectively. In the subgroup of patients evaluated with (18)FDG-PET, no significant differences were observed in SUV between both groups (7.0 ± 3.6 vs 8.2 ± 3.4 respectively; P = .47). In patients with nonischemic HF, the addition of TMZ to optimal medical treatment does not result in significant changes of LVEF, exercise capacity, O2 uptake, or

  8. Effects of auriculotherapy on labour pain: a randomized clinical trial.

    PubMed

    Mafetoni, Reginaldo Roque; Shimo, Antonieta Keiko Kakuda

    2016-01-01

    Assessing the effects of auriculotherapy in pain control and its outcomes on the duration of labour. This is a randomized, controlled, double-blind trial with preliminary data. Thirty pregnant women with gestational age ≥ 37 weeks, cervical dilatation ≥ 4 cm and two or more contractions in 10 minutes were selected and randomly divided into three groups: auriculotherapy, placebo and control. Auriculotherapy was applied using crystal beads on four strategic points. No statistical significance was found between the groups with regard to pain; however, the women from the auriculotherapy group had lower intensity and less perception of pain at 30, 60 and 120 minutes of treatment. The average duration of labour was shorter in the auriculotherapy group (248.7 versus placebo 414.8 versus control 296.3 minutes); caesarean section rates were higher in the placebo group (50%) and the same in the other groups (10%). Mothers who received auriculotherapy presented a tendency for greater pain control and shorter labour duration; however, caesarean section rates in this group were similar to the control group. This trial precedes a larger study in progress. Registration of Brazilian Clinical Trials: RBR-47hhbj. Avaliar os efeitos da auriculoterapia no controle da dor e seus desfechos na duração do trabalho de parto. Trata-se de um ensaio controlado, randomizado e duplo-cego, com dados preliminares. Foram selecionadas 30 parturientes com idade gestacional ≥ 37 semanas, dilatação cervical ≥ 4 cm e duas ou mais contrações em 10 minutos, divididas aleatoriamente em três grupos: auriculoterapia, placebo ou controle. A auriculoterapia foi aplicada com microesferas de cristais em quatro pontos estratégicos. Não houve significância estatística entre os grupos com relação à dor; no entanto, as mulheres do grupo de auriculoterapia, apresentaram menor intensidade e menor percepção da dor aos 30, 60 e 120 minutos do tratamento. A média de duração do trabalho de

  9. Random Field effects in perpendicular-anisotropy multilayer films

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Silevitch, Daniel; Rosenbaum, Thomas

    With the application of a magnetic field transverse to the magnetic easy axis, randomly-distributed 3D collections of dipole-coupled Ising spins form a realization of the Random-Field Ising Model. Tuning the strength of the site-specific random field, and hence the disorder, via the applied transverse field regulates the domain reversal energetics and hence the macroscopic hysteresis loop. We extend this approach to two dimensions, using sputtered Perpendicular Magnetic Anisotropy (PMA) Co/Pt multilayer thin films. We characterize the coercive fields and hysteresis loops at a series of temperatures and transverse fields.

  10. RANDOM WALKS AND EFFECTIVE OPTICAL DEPTH IN RELATIVISTIC FLOW

    SciTech Connect

    Shibata, Sanshiro; Tominaga, Nozomu; Tanaka, Masaomi

    2014-05-20

    We investigate the random walk process in relativistic flow. In the relativistic flow, photon propagation is concentrated in the direction of the flow velocity due to the relativistic beaming effect. We show that in the pure scattering case, the number of scatterings is proportional to the size parameter ξ ≡ L/l {sub 0} if the flow velocity β ≡ v/c satisfies β/Γ >> ξ{sup –1}, while it is proportional to ξ{sup 2} if β/Γ << ξ{sup –1}, where L and l {sub 0} are the size of the system in the observer frame and the mean free path in the comoving frame, respectively. We also examine the photon propagation in the scattering and absorptive medium. We find that if the optical depth for absorption τ{sub a} is considerably smaller than the optical depth for scattering τ{sub s} (τ{sub a}/τ{sub s} << 1) and the flow velocity satisfies β≫√(2τ{sub a}/τ{sub s}), then the effective optical depth is approximated by τ{sub *} ≅ τ{sub a}(1 + β)/β. Furthermore, we perform Monte Carlo simulations of radiative transfer and compare the results with the analytic expression for the number of scatterings. The analytic expression is consistent with the results of the numerical simulations. The expression derived in this study can be used to estimate the photon production site in relativistic phenomena, e.g., gamma-ray burst and active galactic nuclei.

  11. Randomness versus deterministic chaos: Effect on invasion percolation clusters

    NASA Astrophysics Data System (ADS)

    Peng, Chung-Kang; Prakash, Sona; Herrmann, Hans J.; Stanley, H. Eugene

    1990-10-01

    What is the difference between randomness and chaos \\? Although one can define randomness and one can define chaos, one cannot easily assess the difference in a practical situation. Here we compare the results of these two antipodal approaches on a specific example. Specifically, we study how well the logistic map in its chaotic regime can be used as quasirandom number generator by calculating pertinent properties of a well-known random process: invasion percolation. Only if λ>λ*1 (the first reverse bifurcation point) is a smooth extrapolation in system size possible, and percolation exponents are retrieved. If λ≠1, a sequential filling of the lattice with the random numbers generates a measurable anisotropy in the growth sequence of the clusters, due to short-range correlations.

  12. Effect of randomly varying impedance on the interference of the direct and ground-reflected waves.

    PubMed

    Ostashev, Vladimir E; Wilson, D Keith; Vecherin, Sergey N

    2011-10-01

    A randomly varying ground impedance is introduced into the solution for the sound field produced by a point source in a homogeneous atmosphere above a flat ground. The results show that in general the ground with a random impedance cannot be represented by an effective, non-random impedance. The behavior of the solution is studied with a relaxation model for the impedance in which porosity and the static flow resistivity are random variables. Mean values and standard deviations are adopted from measurements of two types of ground surfaces. For both surfaces, the mean intensity of the sound field above a random-impedance ground deviates only slightly from the intensity above a non-random impedance. The normalized standard deviation of intensity fluctuations can, however, be greater than one, thus indicating that for a particular realization of the random impedance, the sound intensity might significantly deviate from the intensity for a non-random impedance.

  13. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering

    NASA Technical Reports Server (NTRS)

    Zhu, P. Y.; Fung, A. K.

    1986-01-01

    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  14. Effective medium approximation for effective propagation constant calculation in a dense random medium. [electromagnetic wave scattering

    NASA Technical Reports Server (NTRS)

    Zhu, P. Y.; Fung, A. K.

    1986-01-01

    The effective medium approximation (EMA) formalism developed for scalar wave calculations in solid state physics is generalized to electromagnetic wave scattering in a dense random medium. Results are applied to compute the effective propagation constant in a dense medium involving discrete spherical scatterers. When compared with a common quasicrystalline approximation (QCA), it is found that EMA accounts for backward scattering and the effect of correlation among three scatterers which are not available in QCA. It is also found that there is not much difference in the calculated normalized phase velocity between the use of these two approximations. However, there is a significant difference in the computed effective loss tangent in a nonabsorptive random medium. The computed effective loss tangent using EMA and measurements from a snow medium are compared, showing good agreement.

  15. Examples of Mixed-Effects Modeling with Crossed Random Effects and with Binomial Data

    ERIC Educational Resources Information Center

    Quene, Hugo; van den Bergh, Huub

    2008-01-01

    Psycholinguistic data are often analyzed with repeated-measures analyses of variance (ANOVA), but this paper argues that mixed-effects (multilevel) models provide a better alternative method. First, models are discussed in which the two random factors of participants and items are crossed, and not nested. Traditional ANOVAs are compared against…

  16. Effects of Check & Connect on Attendance, Behavior, and Academics: A Randomized Effectiveness Trial

    ERIC Educational Resources Information Center

    Maynard, Brandy R.; Kjellstrand, Elizabeth K.; Thompson, Aaron M.

    2014-01-01

    The present study evaluates the effectiveness of Check & Connect (C&C) in a randomly assigned sample of students who were all receiving Communities in Schools (CIS) services. The research questions for the study include: Are there differences in attendance, academics, and behavior for CIS students who also receive C&C compared to…

  17. Examples of Mixed-Effects Modeling with Crossed Random Effects and with Binomial Data

    ERIC Educational Resources Information Center

    Quene, Hugo; van den Bergh, Huub

    2008-01-01

    Psycholinguistic data are often analyzed with repeated-measures analyses of variance (ANOVA), but this paper argues that mixed-effects (multilevel) models provide a better alternative method. First, models are discussed in which the two random factors of participants and items are crossed, and not nested. Traditional ANOVAs are compared against…

  18. Fixed and random effect analysis of multi-subject fMRI data using wavelet transform.

    PubMed

    Soleymani, Mohammad; Hossein-Zadeh, Gholam-Ali; Soltanian-Zadeh, Hamid

    2009-01-30

    We propose a new method to estimate the random effect variance in group analysis of fMRI data. In the first level of analysis, general linear model (GLM) is used to estimate a parameter map ("effect") for each subject. After applying discrete wavelet transform to the "effect" maps, noise is reduced through a vertical energy thresholding (VET). The fixed effect component in each coefficient is derived by averaging the wavelet coefficients along all subjects. Then, the wavelet coefficients containing significant random effect are identified by their higher sample variance along the subjects. Wavelet coefficients containing random effect component in each subject are used to reconstruct the random effect maps through an inverse wavelet transform. Random effect variance is obtained from random effect maps for use in random effect analysis. The proposed method and other methods like GLM group analysis and variance ratio smoothing are applied to both experimental and artificial fMRI data. ROC curves, obtained from the simulated data, show improved group activation detection compared to existing random effect analysis methods. For the experimental data, the proposed method shows its high sensitivity by detecting multiple activation regions, namely visual cortex, cuneus, precuneus, thalamus, and cerebellum. From these regions, precuneus and cerebellum are not detected by majority of the previously published methods.

  19. Random effects coefficient of determination for mixed and meta-analysis models.

    PubMed

    Demidenko, Eugene; Sargent, James; Onega, Tracy

    2012-01-01

    The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine.

  20. Random-effects models for meta-analytic structural equation modeling: review, issues, and illustrations.

    PubMed

    Cheung, Mike W-L; Cheung, Shu Fai

    2016-06-01

    Meta-analytic structural equation modeling (MASEM) combines the techniques of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Both fixed-effects and random-effects models can be defined in MASEM. Random-effects models are well known in conventional meta-analysis but are less studied in MASEM. The primary objective of this paper was to address issues related to random-effects models in MASEM. Specifically, we compared two different random-effects models in MASEM-correlation-based MASEM and parameter-based MASEM-and explored their strengths and limitations. Two examples were used to illustrate the similarities and differences between these models. We offered some practical guidelines for choosing between these two models. Future directions for research on random-effects models in MASEM were also discussed. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Effect of local A-site strain on dipole stability in A6GaNb9O30 (A = Ba, Sr, Ca) tetragonal tungsten bronze relaxor dielectrics.

    PubMed

    Miller, Andrew J; Rotaru, Andrei; Arnold, Donna C; Morrison, Finlay D

    2015-06-21

    A series of isovalently A-site substituted relaxor dielectric tetragonal tungsten bronzes of general formula Ba(6-x-y)Sr(x)Ca(y)GaNb(9)O(30) were investigated. The long-range (average) crystal structure as determined by conventional diffraction techniques varies monotonically according to Vegard's law. The dielectric properties, however, do not display a similar, simple "average size" dependence and instead show a dependence on the statistical size variance, i.e. size mismatch, of the A-cation. The difficulties in Vogel-Fulcher analysis of relative permittivity and the complementary approach of using dielectric loss data fitted to Jonscher's empirical universal dielectric relaxation model is discussed.

  2. A-site substitution effect of perovskite-type cobalt and manganese oxides on two-step water splitting reaction for solar hydrogen production

    NASA Astrophysics Data System (ADS)

    Kaneko, Hiroshi; Hasegawa, Takumi; Mori, Kohei

    2017-06-01

    The perovskite type metal oxides (ABO3: A and B are metal elements) are attractive material for the two-step water splitting process to produce solar hydrogen, because the diversity of perovskite compound with substitution of metal ion makes its reducibility changeable. The perovskite-type cobalt and manganese oxides are prepared with substitution of metal ion in the A-site, and the performance of two-step water splitting reaction is investigated. The LaCoO3 and Ca0.45Sr0.4La0.15MnO3-δ, containing more trivalent metal ions in the A-site of perovskite structure, are most promising materials for solar hydrogen production. It is found that the two-step water-splitting reaction with Ca0.45Sr0.4La0.15MnO3-δ of the perovskite-type manganese oxide proceed stoichiometrically and Ca0.45Sr0.4La0.15MnO3-δ can produce much H2 gas (4cm3/g-sample) at the reduction temperature of 1400 °C.

  3. A likelihood reformulation method in non-normal random effects models.

    PubMed

    Liu, Lei; Yu, Zhangsheng

    2008-07-20

    In this paper, we propose a practical computational method to obtain the maximum likelihood estimates (MLE) for mixed models with non-normal random effects. By simply multiplying and dividing a standard normal density, we reformulate the likelihood conditional on the non-normal random effects to that conditional on the normal random effects. Gaussian quadrature technique, conveniently implemented in SAS Proc NLMIXED, can then be used to carry out the estimation process. Our method substantially reduces computational time, while yielding similar estimates to the probability integral transformation method (J. Comput. Graphical Stat. 2006; 15:39-57). Furthermore, our method can be applied to more general situations, e.g. finite mixture random effects or correlated random effects from Clayton copula. Simulations and applications are presented to illustrate our method.

  4. Side effects can enhance treatment response through expectancy effects: an experimental analgesic randomized controlled trial.

    PubMed

    Berna, Chantal; Kirsch, Irving; Zion, Sean R; Lee, Yvonne C; Jensen, Karin B; Sadler, Pamela; Kaptchuk, Ted J; Edwards, Robert R

    2017-02-04

    In randomized controlled trials, medication side effects may lead to beliefs that one is receiving the active intervention and enhance active treatment responses, thereby increasing drug-placebo differences. We tested these hypotheses with an experimental double-blind randomized controlled trial of a nonsteroidal anti-inflammatory drug with and without the addition of atropine to induce side effects. One hundred healthy volunteers were told they would be randomized to either combined analgesics that might produce dry mouth or inert placebos. In reality, they were randomized double blind, double-dummy to 1 of the 4 conditions: (1) 100 mg diclofenac + 1.2 mg atropine, (2) placebo + 1.2 mg atropine, (3) 100 mg diclofenac + placebo, or (4) placebo + placebo, and tested with heat-induced pain. Groups did not differ significantly in demographics, temperature producing moderate pain, state anxiety, or depression. Analgesia was observed in all groups; there was a significant interaction between diclofenac and atropine, without main effects. Diclofenac alone was not better than double-placebo. The addition of atropine increased pain relief more than 3-fold among participants given diclofenac (d = 0.77), but did not enhance the response to placebo (d = 0.09). A chain of mediation analysis demonstrated that the addition of atropine increased dry mouth symptoms, which increased beliefs that one had received the active medication, which, in turn, increased analgesia. In addition to this indirect effect of atropine on analgesia (via dry mouth and beliefs), analyses suggest that among those who received diclofenac, atropine directly increased analgesia. This possible synergistic effect between diclofenac and atropine might warrant future research.

  5. Effects of random rewiring on the degree correlation of scale-free networks

    PubMed Central

    Qu, Jing; Wang, Sheng-Jun; Jusup, Marko; Wang, Zhen

    2015-01-01

    Random rewiring is used to generate null networks for the purpose of analyzing the topological properties of scale-free networks, yet the effects of random rewiring on the degree correlation are subject to contradicting interpretations in the literature. We comprehensively analyze the degree correlation of randomly rewired scale-free networks and show that random rewiring increases disassortativity by reducing the average degree of the nearest neighbors of high-degree nodes. The effect can be captured by the measures of the degree correlation that consider all links in the network, but not by analogous measures that consider only links between degree peers, hence the potential for contradicting interpretations. We furthermore find that random and directional rewiring affect the topology of a scale-free network differently, even if the degree correlation of the rewired networks is the same. Consequently, the network dynamics is changed, which is proven here by means of the biased random walk. PMID:26482005

  6. Effects of random rewiring on the degree correlation of scale-free networks.

    PubMed

    Qu, Jing; Wang, Sheng-Jun; Jusup, Marko; Wang, Zhen

    2015-10-20

    Random rewiring is used to generate null networks for the purpose of analyzing the topological properties of scale-free networks, yet the effects of random rewiring on the degree correlation are subject to contradicting interpretations in the literature. We comprehensively analyze the degree correlation of randomly rewired scale-free networks and show that random rewiring increases disassortativity by reducing the average degree of the nearest neighbors of high-degree nodes. The effect can be captured by the measures of the degree correlation that consider all links in the network, but not by analogous measures that consider only links between degree peers, hence the potential for contradicting interpretations. We furthermore find that random and directional rewiring affect the topology of a scale-free network differently, even if the degree correlation of the rewired networks is the same. Consequently, the network dynamics is changed, which is proven here by means of the biased random walk.

  7. The electronic structure of RbTiOPO4 and the effects of the A-site cation substitution in KTiOPO4-family crystals.

    PubMed

    Atuchin, V V; Kesler, V G; Meng, Guangsi; Lin, Z S

    2012-10-10

    The electronic structure of RbTiOPO(4) has been investigated with x-ray photoemission spectroscopy. Detailed photoemission spectra of the element core levels have been recorded under excitation by nonmonochromatic Al Kα radiation (1486.6 eV). The chemical bonding parameters are compared to those reported for complex titanates and phosphates. The band structures of KTiOPO(4), RbTiOPO(4), K(0.535)R(0.465)TiOPO(4) and TlTiOPO(4) have been calculated by ab initio methods and compared to available experimental results. It is found that the band structure of KTP-type phosphate crystals is weakly dependent on the nature of the A-site (A=K, Rb, Tl) element.

  8. The effect of microscale random Alfven waves on the propagation of large-scale Alfven waves

    NASA Astrophysics Data System (ADS)

    Namikawa, T.; Hamabata, H.

    1983-04-01

    The ponderomotive force generated by random Alfven waves in a collisionless plasma is evaluated taking into account mean magnetic and velocity shear and is expressed as a series involving spatial derivatives of mean magnetic and velocity fields whose coefficients are associated with the helicity spectrum function of random velocity field. The effect of microscale random Alfven waves through ponderomotive and mean electromotive forces generated by them on the propagation of large-scale Alfven waves is also investigated.

  9. Hydraulic conductivity of stratified unsaturated soils: Effects of random variability and layering

    NASA Astrophysics Data System (ADS)

    Gohardoust, Mohammad R.; Sadeghi, Morteza; Ziatabar Ahmadi, Mirkhalegh; Jones, Scott B.; Tuller, Markus

    2017-03-01

    For simulating flow in heterogeneous porous media it is computationally more efficient to define an equivalent effective (i.e., upscaled) medium rather than considering detailed spatial heterogeneities. In this paper, the effective unsaturated hydraulic conductivity (K) of soils exhibiting random variability, layering, or both is calculated based on numerical simulations of steady-state evaporation from a shallow water table. It is demonstrated that the effective K of randomly-varied coarse-textured soils generally falls between the harmonic and geometric means of the unsaturated hydraulic conductivities of the constituting soils. Layering and random variability when occurring concurrently magnify each other's effects on effective K. As a result, the higher the degree of heterogeneity, the lower the effective K. Therefore, neglecting either random spatial variability or layering in numerical simulations can lead to significant overestimation of water flow in soils.

  10. The Effectiveness of Mandatory-Random Student Drug Testing. NCEE 2010-4025

    ERIC Educational Resources Information Center

    James-Burdumy, Susanne; Goesling, Brian; Deke, John; Einspruch, Eric

    2010-01-01

    To help assess the effects of school-based random drug testing programs, the U.S. Department of Education's Institute of Education Sciences (IES) contracted with RMC Research Corporation and Mathematica Policy Research to conduct an experimental evaluation of the Mandatory-Random Student Drug Testing (MRSDT) programs in 36 high schools within…

  11. Evaluation of some random effects methodology applicable to bird ringing data

    USGS Publications Warehouse

    Burnham, K.P.; White, Gary C.

    2002-01-01

    Existing models for ring recovery and recapture data analysis treat temporal variations in annual survival probability (S) as fixed effects. Often there is no explainable structure to the temporal variation in S1,..., Sk; random effects can then be a useful model: Si = E(S) + ??i. Here, the temporal variation in survival probability is treated as random with average value E(??2) = ??2. This random effects model can now be fit in program MARK. Resultant inferences include point and interval estimation for process variation, ??2, estimation of E(S) and var (E??(S)) where the latter includes a component for ??2 as well as the traditional component for v??ar(S??\\S??). Furthermore, the random effects model leads to shrinkage estimates, Si, as improved (in mean square error) estimators of Si compared to the MLE, S??i, from the unrestricted time-effects model. Appropriate confidence intervals based on the Si are also provided. In addition, AIC has been generalized to random effects models. This paper presents results of a Monte Carlo evaluation of inference performance under the simple random effects model. Examined by simulation, under the simple one group Cormack-Jolly-Seber (CJS) model, are issues such as bias of ??s2, confidence interval coverage on ??2, coverage and mean square error comparisons for inference about Si based on shrinkage versus maximum likelihood estimators, and performance of AIC model selection over three models: Si ??? S (no effects), Si = E(S) + ??i (random effects), and S1,..., Sk (fixed effects). For the cases simulated, the random effects methods performed well and were uniformly better than fixed effects MLE for the Si.

  12. Randomized controlled trial of sealed in-office bleaching effectiveness.

    PubMed

    Santana, Mário Artur Pereira; Nahsan, Flávia Pardo Salata; Oliveira, Alaíde Hermínia de Aguiar; Loguércio, Alessandro Dourado; Faria-e-Silva, André Luis

    2014-01-01

    Regardless of the high success rate, patients commonly report the occurrence of tooth sensitivity during the in-office bleaching procedures. Recently, it has been demonstrated that using a customized tray (called sealed in-office bleaching technique) reduces peroxide penetration. The aim of this randomized clinical study was to evaluate tooth sensitivity and bleaching efficacy of sealed bleaching, in comparison with a conventional in-office technique. Twenty patients were randomized allocated in two groups in which 35% hydrogen peroxide gel was used in a single 45-min application. For the sealed technique, a customized bleaching tray was fabricated and carefully positioned over the bleaching agent during the session. The color was recorded at a baseline, 7 and 28 days after the bleaching session, using Vita Easy Shade spectrophotometer. Tooth sensitivity was recorded during (20 and 40 min) and immediately after the treatment using a visual analogue scale. The bleaching efficacy was evaluated by repeated-measures ANOVA, while the absolute risk of tooth sensitivity and its intensity were evaluated by Fisher's exact and Mann-Whitney tests, respectively (α=0.05). No significant difference on bleaching efficacy was observed between the conventional (7.4 and 8.1 ΔE) and sealed techniques (7.8 and 8.3 ΔE) at both evaluation periods. No significant difference was observed regarding the absolute risk of tooth sensitivity (p=0.15). Sealed technique showed a significant decrease of sensitivity intensity after 40 min (p=0.03). Sealed bleaching technique was able to reduce the sensitivity intensity during the bleaching procedure, without jeopardizing the bleaching efficacy.

  13. Identification of causal effects using instrumental variables in randomized trials with stochastic compliance.

    PubMed

    Scosyrev, Emil

    2013-01-01

    In randomized trials with imperfect compliance, it is sometimes recommended to supplement the intention-to-treat estimate with an instrumental variable (IV) estimate, which is consistent for the effect of treatment administration in those subjects who would get treated if randomized to treatment and would not get treated if randomized to control. The IV estimation however has been criticized for its reliance on simultaneous existence of complementary "fatalistic" compliance states. The objective of the present paper is to identify some sufficient conditions for consistent estimation of treatment effects in randomized trials with stochastic compliance. It is shown that in the stochastic framework, the classical IV estimator is generally inconsistent for the population-averaged treatment effect. However, even under stochastic compliance, with certain common experimental designs the IV estimator and a simple alternative estimator can be used for consistent estimation of the effect of treatment administration in well-defined and identifiable subsets of the study population.

  14. Shape effects on the random-packing density of tetrahedral particles.

    PubMed

    Zhao, Jian; Li, Shuixiang; Jin, Weiwei; Zhou, Xuan

    2012-09-01

    Regular tetrahedra have been demonstrated recently giving high packing density in random configurations. However, it is unknown whether the random-packing density of tetrahedral particles with other shapes can reach an even higher value. A numerical investigation on the random packing of regular and irregular tetrahedral particles is carried out. Shape effects of rounded corner, eccentricity, and height on the packing density of tetrahedral particles are studied. Results show that altering the shape of tetrahedral particles by rounding corners and edges, by altering the height of one vertex, or by lateral displacement of one vertex above its opposite face, all individually have the effect of reducing the random-packing density. In general, the random-packing densities of irregular tetrahedral particles are lower than that of regular tetrahedra. The ideal regular tetrahedron should be the shape which has the highest random-packing density in the family of tetrahedra, or even among convex bodies. An empirical formula is proposed to describe the rounded corner effect on the packing density, and well explains the density deviation of tetrahedral particles with different roundness ratios. The particles in the simulations are verified to be randomly packed by studying the pair correlation functions, which are consistent with previous results. The spherotetrahedral particle model with the relaxation algorithm is effectively applied in the simulations.

  15. Conceptualizing and Testing Random Indirect Effects and Moderated Mediation in Multilevel Models: New Procedures and Recommendations

    ERIC Educational Resources Information Center

    Bauer, Daniel J.; Preacher, Kristopher J.; Gil, Karen M.

    2006-01-01

    The authors propose new procedures for evaluating direct, indirect, and total effects in multilevel models when all relevant variables are measured at Level 1 and all effects are random. Formulas are provided for the mean and variance of the indirect and total effects and for the sampling variances of the average indirect and total effects.…

  16. Modeling multivariate survival data by a semiparametric random effects proportional odds model.

    PubMed

    Lam, K F; Lee, Y W; Leung, T L

    2002-06-01

    In this article, the focus is on the analysis of multivariate survival time data with various types of dependence structures. Examples of multivariate survival data include clustered data and repeated measurements from the same subject, such as the interrecurrence times of cancer tumors. A random effect semiparametric proportional odds model is proposed as an alternative to the proportional hazards model. The distribution of the random effects is assumed to be multivariate normal and the random effect is assumed to act additively to the baseline log-odds function. This class of models, which includes the usual shared random effects model, the additive variance components model, and the dynamic random effects model as special cases, is highly flexible and is capable of modeling a wide range of multivariate survival data. A unified estimation procedure is proposed to estimate the regression and dependence parameters simultaneously by means of a marginal-likelihood approach. Unlike the fully parametric case, the regression parameter estimate is not sensitive to the choice of correlation structure of the random effects. The marginal likelihood is approximated by the Monte Carlo method. Simulation studies are carried out to investigate the performance of the proposed method. The proposed method is applied to two well-known data sets, including clustered data and recurrent event times data.

  17. A random effects meta-analysis model with Box-Cox transformation.

    PubMed

    Yamaguchi, Yusuke; Maruo, Kazushi; Partlett, Christopher; Riley, Richard D

    2017-07-19

    In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatment effect, an inappropriate quantification of heterogeneity across studies and a wrongly symmetric prediction interval. We focus on problems caused by an inappropriate normality assumption of the random effects distribution, and propose a novel random effects meta-analysis model where a Box-Cox transformation is applied to the observed treatment effect estimates. The proposed model aims to normalise an overall distribution of observed treatment effect estimates, which is sum of the within-study sampling distributions and the random effects distribution. When sampling distributions are approximately normal, non-normality in the overall distribution will be mainly due to the random effects distribution, especially when the between-study variation is large relative to the within-study variation. The Box-Cox transformation addresses this flexibly according to the observed departure from normality. We use a Bayesian approach for estimating parameters in the proposed model, and suggest summarising the meta-analysis results by an overall median, an interquartile range and a prediction interval. The model can be applied for any kind of variables once the treatment effect estimate is defined from the variable. A simulation study suggested that when the overall distribution of treatment effect estimates are skewed, the overall mean and conventional I (2) from the normal random effects model could be inappropriate summaries, and the proposed model helped reduce this issue. We illustrated the proposed model using two examples, which revealed some important differences on summary results, heterogeneity measures and prediction intervals from the normal random effects model

  18. Teacher Effects in Early Grades: Evidence from a Randomized Study

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2011-01-01

    Background/Context: One important question to educational research is whether teachers can influence student achievement over time. This question is related to the durability of teacher effects on student achievement in successive grades. The research evidence about teacher effects on student achievement has been somewhat mixed. Some education…

  19. Teacher Effects in Early Grades: Evidence from a Randomized Study

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2011-01-01

    Background/Context: One important question to educational research is whether teachers can influence student achievement over time. This question is related to the durability of teacher effects on student achievement in successive grades. The research evidence about teacher effects on student achievement has been somewhat mixed. Some education…

  20. The impact of omitting the interaction between crossed factors in cross-classified random effects modelling.

    PubMed

    Shi, Yuying; Leite, Walter; Algina, James

    2010-02-01

    Cross-classified random effects modelling (CCREM) is a special case of multi-level modelling where the units of one level are nested within two cross-classified factors. Typically, CCREM analyses omit the random interaction effect of the cross-classified factors. We investigate the impact of the omission of the interaction effect on parameter estimates and standard errors. Results from a Monte Carlo simulation study indicate that, for fixed effects, both coefficients estimates and accompanied standard error estimates are not biased. For random effects, results are affected at level 2 but not at level 1 by the presence of an interaction variance and/or a correlation between the residual of level two factors. Results from the analysis of the Early Childhood Longitudinal Study and the National Educational Longitudinal Study agree with those obtained from simulated data. We recommend that researchers attempt to include interaction effects of cross-classified factors in their models.

  1. Investigating the effective factors in creatinine changes among hemodialysis patients using the linear random effects model

    PubMed Central

    Shabankhani, B; Kazemnezhad, A; Zaeri, F

    2015-01-01

    Background and objectives:Out of 10 apparently healthy humans, one was somewhat suffering from one of the types of renal disease. Hemodialysis is known as the most applicable method of taking care of this group of patients. In addition, serum creatinine is an important mark in the performance of kidneys. The aim of the present study was to investigate the effective factors in creatinine and its effect on the performance of kidneys. Materials and methods: The present study is a longitudinal experiment in which 500 participants were randomly selected from the hemodialysis patients in Mazandaran Province. Creatinine variable was considered as the longitudinal responding variable, which was measured 3 times per year over a period of 6 years. The random effects model was also considered the most appropriate model for the collected data. Results:The total mean value of creatinine was 1.62 ± 0.49, among men 1.69 ± 0.46 and among women 35.1 ± 0.49. Variables of weight (p<0.001), age of disease diagnosis (p<0.001), time (p<0.001), gender (p<0.005), and cardiovascular diseases were significant and had effects on the trend of creatinine changes among the hemodialysis patients. Creatinine mean value had an increasing trend. Conclusion:Blood creatinine had a significant effect on the performance of kidneys, and the identification of variables that affected the creatinine level was highly helpful in controlling the performance of the kidneys. The results of most studies conducted on hemodialysis patients indicated that by measuring and controlling variables like weight, tobacco consumption, and control of related diseases like blood pressure could predict and control creatinine changes precisely. PMID:28255403

  2. Electron correlation effects beyond the random phase approximation

    NASA Astrophysics Data System (ADS)

    Fan, J. D.; Malozovsky, Y. M.

    2016-04-01

    The methods that have been used to deal with a many-particle system can be basically sorted into three types: Hamiltonian, field theory and phenomenological method. The first two methods are more popular. Traditionally, the Hamiltonian method has been widely adopted in the conventional electronic theory for metals, alloys and semiconductors. Basically, the mean-field approximation (MFA) that has been working well for a weakly coupled system like a metal is employed to simplify a Hamiltonian corresponding to a particular electron system. However, for a strongly coupled many-particle system like a cuprate superconductor MFA should in principle not apply. Therefore, the field theory on the basis of Green’s function and the Feynman diagrams must be invoked. In this method, one is however more familiar with the random phase approximation (RPA) that gives rise to the same results as MFA because of being short of the information for higher-order terms of interaction. For a strongly coupled electron system, it is obvious that one has to deal with higher-order terms of a pair interaction to get a correct solution. Any ignorance of the higher-order terms implies that the more sophisticated information contained in those terms is discarded. However, to date one has not reached a consensus on how to deal with the higher-order terms beyond RPA. We preset here a method that is termed the diagrammatic iteration approach (DIA) and able to derive higher-order terms of the interaction from the information of lower-order ones on the basis of Feynman diagram, with which one is able to go beyond RPA step by step. It is in principle possible that all of higher-order terms can be obtained, and then sorted to groups of diagrams. It turns out that each of the groups can be replaced by an equivalent one, forming a diagrammatic Dyson-equation-like relation. The diagrammatic solution is eventually “translated” to a four-dimensional integral equation. The method can be applied to a

  3. Nifedipine versus terbutaline, tocolytic effectiveness and maternal and neonatal adverse effects: a randomized, controlled pilot trial.

    PubMed

    Padovani, Tania Regina; Guyatt, Gordon; Lopes, Luciane Cruz

    2015-03-01

    Although previous evidence suggests advantages of nifedipine over terbutaline as tocolytic agents, in some jurisdictions, terbutaline is approved for use and nifedipine is not. In women in preterm labour, we compared the impact of terbutaline versus nifedipine on inhibition of uterine contractions, preterm birth, neonatal sepsis, intracranial haemorrhage or necrotizing enterocolitis, death or admission to a neonatal intensive care unit and maternal adverse reactions. We randomized 32 women to nifedipine and 34 to terbutaline. We found no difference between groups in tocolysis or preterm birth. No serious maternal adverse effects or serious neonatal adverse outcome occurred in either group. Less serious maternal adverse effects less common with terbutaline included flushing (2.94% versus 43.7%) and headache (5.9% versus 31.2%). The administration of terbutaline increased tremor (76.4% versus 0%), nausea (58.8% versus 9.4%) and dizziness (29.4% versus 6.25%). The total number of side effects, and the proportion of women experiencing one or more side effects, proved greater with terbutaline. In this study, terbutaline and nifedipine performed similarly in their tocolytic effects. Each drug has specific side effects, although overall, nifedipine was associated with fewer adverse effects. © 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  4. Asymptotic Effect of Misspecification in the Random Part of the Multilevel Model

    ERIC Educational Resources Information Center

    Berkhof, Johannes; Kampen, Jarl Kennard

    2004-01-01

    The authors examine the asymptotic effect of omitting a random coefficient in the multilevel model and derive expressions for the change in (a) the variance components estimator and (b) the estimated variance of the fixed effects estimator. They apply the method of moments, which yields a closed form expression for the omission effect. In…

  5. Asymptotic Effect of Misspecification in the Random Part of the Multilevel Model

    ERIC Educational Resources Information Center

    Berkhof, Johannes; Kampen, Jarl Kennard

    2004-01-01

    The authors examine the asymptotic effect of omitting a random coefficient in the multilevel model and derive expressions for the change in (a) the variance components estimator and (b) the estimated variance of the fixed effects estimator. They apply the method of moments, which yields a closed form expression for the omission effect. In…

  6. Standardized Effect Size Measures for Mediation Analysis in Cluster-Randomized Trials

    ERIC Educational Resources Information Center

    Stapleton, Laura M.; Pituch, Keenan A.; Dion, Eric

    2015-01-01

    This article presents 3 standardized effect size measures to use when sharing results of an analysis of mediation of treatment effects for cluster-randomized trials. The authors discuss 3 examples of mediation analysis (upper-level mediation, cross-level mediation, and cross-level mediation with a contextual effect) with demonstration of the…

  7. Standardized Effect Size Measures for Mediation Analysis in Cluster-Randomized Trials

    ERIC Educational Resources Information Center

    Stapleton, Laura M.; Pituch, Keenan A.; Dion, Eric

    2015-01-01

    This article presents 3 standardized effect size measures to use when sharing results of an analysis of mediation of treatment effects for cluster-randomized trials. The authors discuss 3 examples of mediation analysis (upper-level mediation, cross-level mediation, and cross-level mediation with a contextual effect) with demonstration of the…

  8. Semi-parametric estimation of random effects in a logistic regression model using conditional inference.

    PubMed

    Petersen, Jørgen Holm

    2016-01-15

    This paper describes a new approach to the estimation in a logistic regression model with two crossed random effects where special interest is in estimating the variance of one of the effects while not making distributional assumptions about the other effect. A composite likelihood is studied. For each term in the composite likelihood, a conditional likelihood is used that eliminates the influence of the random effects, which results in a composite conditional likelihood consisting of only one-dimensional integrals that may be solved numerically. Good properties of the resulting estimator are described in a small simulation study.

  9. Effects of Cooperative Writing with Embedded Multimedia: A Randomized Experiment

    ERIC Educational Resources Information Center

    Madden, Nancy A.; Slavin, Robert E.; Logan, Michele

    2011-01-01

    The present study represented an effort to improve on the outcomes of the Puma (2006) study by creating a writing process program that provided students with compelling video models of effective writing practices in small writing teams. In this method, called Writing Wings with Media (WWM), students worked in 4-member, heterogeneous writing groups…

  10. Childhood Resiliency Effects from Schoolwide Treatment: A Cluster Randomized Trial

    ERIC Educational Resources Information Center

    Hinerman, Krystal M.; Hull, Darrell M.; Hayes, DeMarquis; Powell, Marvin G.; Ferguson, Sarah; Naslund-Hadley, Emma I.

    2014-01-01

    The purpose of the Childhood Resiliency Effects from Schoolwide Treatment (CREST) Pilot was to implement a comprehensive school wide social and character development program aimed at decreasing violence among students and assisting students exposed to violence in Belize City. This one-year pilot program implemented portions of the Positive Action…

  11. Family Maltreatment, Substance Problems, and Suicidality: Randomized Prevention Effectiveness Trial

    DTIC Science & Technology

    2007-02-01

    PARENTS WHO CARE – GUIDING GOOD CHOICES (AGES 9-14)................................................................................67 PARENTING WISELY...Australia, Couple CARE is a self -directed relationship education activity designed to help couples effectively strengthen their relationships by means of...relationship self -regulation, and less on universal prescriptions for specific skills. Couple CARE can enrich each couple’s relationship by assisting them to

  12. Effective algorithm for random mask generation used in secured optical data encryption and communication

    NASA Astrophysics Data System (ADS)

    Liu, Yuexin; Metzner, John J.; Guo, Ruyan; Yu, Francis T. S.

    2005-09-01

    An efficient and secure algorithm for random phase mask generation used in optical data encryption and transmission system is proposed, based on Diffie-Hellman public key distribution. Thus-generated random mask has higher security due to the fact that it is never exposed to the vulnerable transmitting channels. The effectiveness to retrieve the original image and its robustness against blind manipulation have been demonstrated by our numerical results. In addition, this algorithm can be easily extended to multicast networking system and refresh of this shared random key is also very simple to implement.

  13. Effect of the degree of disorder on electronic and optical properties in random superlattices

    NASA Technical Reports Server (NTRS)

    Wang, E. G.; Su, W. P.; Ting, C. S.

    1994-01-01

    A three-dimensional tight-binding calculation is developed and used to study disorder effects in a realistic random superlattice. With increasing disorder, a tendency of possible indirect-direct band-gap transition is suggested. Direct evidence of mobility edges between localized and extended states in three-dimensional random systems is given. As system disorder increases, the optical absorption intensities increase dramatically from five to forty-five times stronger than the ordered (GaAs)(sub 1)/(AlAs)(sub 1) superlattice. It is believed that the degree of disorder significantly affects electronic and optical properties of GaAs/AlAs random superlattices.

  14. Quantum random walks on congested lattices and the effect of dephasing

    PubMed Central

    Motes, Keith R.; Gilchrist, Alexei; Rohde, Peter P.

    2016-01-01

    We consider quantum random walks on congested lattices and contrast them to classical random walks. Congestion is modelled on lattices that contain static defects which reverse the walker’s direction. We implement a dephasing process after each step which allows us to smoothly interpolate between classical and quantum random walks as well as study the effect of dephasing on the quantum walk. Our key results show that a quantum walker escapes a finite boundary dramatically faster than a classical walker and that this advantage remains in the presence of heavily congested lattices. PMID:26812924

  15. Effect of randomness on multi-frequency aeroelastic responses resolved by Unsteady Adaptive Stochastic Finite Elements

    SciTech Connect

    Witteveen, Jeroen A.S. Bijl, Hester

    2009-10-01

    The Unsteady Adaptive Stochastic Finite Elements (UASFE) method resolves the effect of randomness in numerical simulations of single-mode aeroelastic responses with a constant accuracy in time for a constant number of samples. In this paper, the UASFE framework is extended to multi-frequency responses and continuous structures by employing a wavelet decomposition pre-processing step to decompose the sampled multi-frequency signals into single-frequency components. The effect of the randomness on the multi-frequency response is then obtained by summing the results of the UASFE interpolation at constant phase for the different frequency components. Results for multi-frequency responses and continuous structures show a three orders of magnitude reduction of computational costs compared to crude Monte Carlo simulations in a harmonically forced oscillator, a flutter panel problem, and the three-dimensional transonic AGARD 445.6 wing aeroelastic benchmark subject to random fields and random parameters with various probability distributions.

  16. Effective realization of random magnetic fields in compounds with large single-ion anisotropy

    NASA Astrophysics Data System (ADS)

    Herbrych, J.; Kokalj, J.

    2017-03-01

    We show that spin S =1 system with large and random single-ion anisotropy can be at low energies mapped to a S =1 /2 system with random magnetic fields. This is, for example, realized in Ni (Cl1 -xBrx)2-4 SC (NH2)2 compound (DTNX) and therefore it represents a long-sought realization of random local (on-site) magnetic fields in antiferromagnetic systems. We support the mapping by numerical study of S =1 and effective S =1 /2 anisotropic Heisenberg chains and find excellent agreement for static quantities and also for the spin conductivity. Such systems can therefore be used to study the effects of local random magnetic fields on transport properties.

  17. Worksite intervention effects on sleep quality: a randomized controlled trial.

    PubMed

    Atlantis, Evan; Chow, Chin-Moi; Kirby, Adrienne; Singh, Maria A Fiatarone

    2006-10-01

    Employees with sleep disturbance are at increased risk of disease. Exercise is believed to be effective for improving sleep quality, but few studies have been conducted. This study investigated the effects of a 24-week worksite exercise/behavioral intervention on self-rated sleep quality, via the Pittsburgh Sleep Quality Index (PSQI), in 73 employees. Greater post-test improvements in the PSQI (-2.0 +/- 2.6 vs. -1.3 +/- 2.7 points, p = .006, and -16 +/- 61 vs. -1 +/- 76%, p = .02) were found in treatment versus controls, and in women versus men (by -2.7 points [-5.0 to -0.3 points, p = .03], and by -72% [-142 to -2%, p = .04]). Similar results were found in the shift worker subgroup. Changes in sleep scores were not significantly related to baseline characteristics, changes in psychological health or quality-of-life scores, or level of exercise compliance.

  18. Electric Crosstalk Effect in Valence Change Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Wang, Hong; Wu, Shiwei; Song, Fang; Wang, Zhan; Gao, Haixia; Ma, Xiaohua

    2017-08-01

    Electric crosstalk phenomenon in valence change resistive switching memory (VCM) is systematically investigated. When a voltage is applied on the VCM device, an electric field is formed in the isolated region between the devices, which causes the oxygen vacancies in conductive filaments (CFs) to drift apart, leading to a consequent resistance degradation of the neighboring devices. The effects of distance between memory cells, electrodes widths and physical dimensions of CFs on the memory performance are investigated in this work. Furthermore, the strategies to mitigate electric crosstalk effects are developed. According to the simulation results, the crosstalk phenomenon can become more severe as the distance between memory cells or the electrode width decreases. In order to optimize the device performance, it is helpful to control the location of the break points of CFs in the device close to the top electrode. Alternatively, taking the integration density into account, switching materials with a small field accelerated parameter can also contribute to obtaining a stable performance.

  19. A Markov Chain Model for evaluating the effectiveness of randomized surveillance procedures

    SciTech Connect

    Edmunds, T.A.

    1994-01-01

    A Markov Chain Model has been developed to evaluate the effectiveness of randomized surveillance procedures. The model is applicable for surveillance systems that monitor a collection of assets by randomly selecting and inspecting the assets. The model provides an estimate of the detection probability as a function of the amount of time that an adversary would require to steal or sabotage the asset. An interactive computer code has been written to perform the necessary computations.

  20. What Works Clearinghouse Quick Review: "Have We Identified Effective Teachers? Validating Measures of Effective Teaching Using Random Assignment"

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2013

    2013-01-01

    "Have We Identified Effective Teachers? Validating Measures of Effective Teaching Using Random Assignment" tested whether a measure created by study authors could identify teachers who are effective at increasing student achievement. The authors used 2009-10 school year data to create a single composite measure of teacher effectiveness;…

  1. Heterogeneous Suppression of Sequential Effects in Random Sequence Generation, but Not in Operant Learning.

    PubMed

    Shteingart, Hanan; Loewenstein, Yonatan

    2016-01-01

    There is a long history of experiments in which participants are instructed to generate a long sequence of binary random numbers. The scope of this line of research has shifted over the years from identifying the basic psychological principles and/or the heuristics that lead to deviations from randomness, to one of predicting future choices. In this paper, we used generalized linear regression and the framework of Reinforcement Learning in order to address both points. In particular, we used logistic regression analysis in order to characterize the temporal sequence of participants' choices. Surprisingly, a population analysis indicated that the contribution of the most recent trial has only a weak effect on behavior, compared to more preceding trials, a result that seems irreconcilable with standard sequential effects that decay monotonously with the delay. However, when considering each participant separately, we found that the magnitudes of the sequential effect are a monotonous decreasing function of the delay, yet these individual sequential effects are largely averaged out in a population analysis because of heterogeneity. The substantial behavioral heterogeneity in this task is further demonstrated quantitatively by considering the predictive power of the model. We show that a heterogeneous model of sequential dependencies captures the structure available in random sequence generation. Finally, we show that the results of the logistic regression analysis can be interpreted in the framework of reinforcement learning, allowing us to compare the sequential effects in the random sequence generation task to those in an operant learning task. We show that in contrast to the random sequence generation task, sequential effects in operant learning are far more homogenous across the population. These results suggest that in the random sequence generation task, different participants adopt different cognitive strategies to suppress sequential dependencies when

  2. Size effect of nano scale phase change random access memory.

    PubMed

    Son, Ji Hoon; Choi, HongKyw; Jang, Nakwon; Kim, Hong Seung; Yi, Dong Young; Lee, Seong Hwan

    2010-05-01

    In this paper, we have investigated the size effect of nano scale PRAM using three-dimensional finite element analysis tool. The reset current and temperature profile of PRAM cells with top and bottom electrode contact hole size were calculated by the numerical method. And temperature profile of PRAM unit cell with size and thickness of GST thin film was simulated. As top electrode contact size was smaller, reset current decreased. But these variations couldn't affect to operate memory. On the other hand, as bottom electrode contact size was smaller, reset current abruptly decreased.

  3. Implementing randomized effectiveness trials in large insurance systems.

    PubMed

    Choudhry, Niteesh K; Shrank, William H

    2013-08-01

    The need to identify how best to structure health insurance and to deliver health care services is a central priority for comparative effectiveness research. Studies designed to evaluate these issues are frequently conducted in large insurance systems. We sought to describe the challenges faced when conducting trials in this context. Using the Post-Myocardial Infarction Free Rx Event and Economic Evaluation (MI FREEE) trial as an example, we describe the methodological and practical challenges of conducting trials in large insurance systems. We encountered six key challenges while conducting MI FREEE trial, namely the need to obtain plan sponsor permission to experiment, the desire of plan sponsors to have all of their beneficiaries receive the same intervention, the inaccuracy of claims-based identification methods and the impact of claims lag on the timely enrollment of potentially eligible patients, the reluctance of patients to participate in insurance-based interventions and the potential need for informed consent, the frequent introduction of new cointerventions in real-world delivery systems, and the high rates of loss to follow-up because of insurance "churn." We describe the approaches we used to overcome these challenges. Studies in insurance settings are a powerful and necessary design for evaluating comparative effectiveness interventions. There are numerous strategies to address the potential logistical and methodological challenges that this research environment uniquely creates. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. A spatial error model with continuous random effects and an application to growth convergence

    NASA Astrophysics Data System (ADS)

    Laurini, Márcio Poletti

    2017-10-01

    We propose a spatial error model with continuous random effects based on Matérn covariance functions and apply this model for the analysis of income convergence processes (β -convergence). The use of a model with continuous random effects permits a clearer visualization and interpretation of the spatial dependency patterns, avoids the problems of defining neighborhoods in spatial econometrics models, and allows projecting the spatial effects for every possible location in the continuous space, circumventing the existing aggregations in discrete lattice representations. We apply this model approach to analyze the economic growth of Brazilian municipalities between 1991 and 2010 using unconditional and conditional formulations and a spatiotemporal model of convergence. The results indicate that the estimated spatial random effects are consistent with the existence of income convergence clubs for Brazilian municipalities in this period.

  5. A spatial error model with continuous random effects and an application to growth convergence

    NASA Astrophysics Data System (ADS)

    Laurini, Márcio Poletti

    2017-07-01

    We propose a spatial error model with continuous random effects based on Matérn covariance functions and apply this model for the analysis of income convergence processes (β -convergence). The use of a model with continuous random effects permits a clearer visualization and interpretation of the spatial dependency patterns, avoids the problems of defining neighborhoods in spatial econometrics models, and allows projecting the spatial effects for every possible location in the continuous space, circumventing the existing aggregations in discrete lattice representations. We apply this model approach to analyze the economic growth of Brazilian municipalities between 1991 and 2010 using unconditional and conditional formulations and a spatiotemporal model of convergence. The results indicate that the estimated spatial random effects are consistent with the existence of income convergence clubs for Brazilian municipalities in this period.

  6. Albumin-binding of diclofenac and the effect of a site II inhibitor in the aqueous humor of cataract patients with the instillation of diclofenac.

    PubMed

    Osaki, Takashi; Ozaki, Mineo; Takamura, Norito; Ogata, Kenji; Tokunaga, Jin; Setoguchi, Nao; Arimori, Kazuhiko

    2014-05-01

    Diclofenac instillation has been used widely in cataract surgery to prevent postoperative inflammation. Since diclofenac binds strongly to albumin in the circulation, it does not have a sufficient effect on patients in whom diclofenac binds strongly to albumin in the aqueous humor. A decrease in diclofenac binding and an increase in free diclofenac levels are necessary in these patients. The binding of diclofenac to albumin was investigated in the aqueous humor. In a diclofenac binding assay with albumin in the aqueous humor of individual patients, diclofenac was extracted from aliquots of the aqueous humor, and its total levels were measured using ultra high performance liquid chromatography (UHPLC). Free diclofenac levels were measured using ultrafiltration and UHPLC. The albumin-binding fraction of diclofenac was 0.8 or higher in the aqueous humor of some patients. Ibuprofen significantly inhibited diclofenac binding to site II of albumin in mimic aqueous humor, but not in pooled aqueous humor. This difference may have been due to the weak binding of diclofenac to site II in the pooled aqueous humor. Flurbiprofen was used instead of diclofenac. Flurbiprofen has been shown to bind more strongly than diclofenac to the same site of albumin. Thus, the inhibitory effect of ibuprofen on the binding of flurbiprofen to albumin was investigated in pooled aqueous humor. The results indicated that ibuprofen significantly inhibited the flurbiprofen binding. An effective diclofenac administration method may be established for clinical application by the instillation of an appropriate inhibitor of binding to the albumin site II. Copyright © 2014 John Wiley & Sons, Ltd.

  7. Note on an Identity Between Two Unbiased Variance Estimators for the Grand Mean in a Simple Random Effects Model.

    PubMed

    Levin, Bruce; Leu, Cheng-Shiun

    2013-01-01

    We demonstrate the algebraic equivalence of two unbiased variance estimators for the sample grand mean in a random sample of subjects from an infinite population where subjects provide repeated observations following a homoscedastic random effects model.

  8. SEMIPARAMETRIC TRANSFORMATION MODELS WITH RANDOM EFFECTS FOR CLUSTERED FAILURE TIME DATA

    PubMed Central

    Zeng, Donglin; Lin, D. Y.; Lin, Xihong

    2009-01-01

    We propose a general class of semiparametric transformation models with random effects to formulate the effects of possibly time-dependent covariates on clustered or correlated failure times. This class encompasses all commonly used transformation models, including proportional hazards and proportional odds models, and it accommodates a variety of random-effects distributions, particularly Gaussian distributions. We show that the nonparametric maximum likelihood estimators of the model parameters are consistent, asymptotically normal and asymptotically efficient. We develop the corresponding likelihood-based inference procedures. Simulation studies demonstrate that the proposed methods perform well in practical situations. An illustration with a well-known diabetic retinopathy study is provided. PMID:19809573

  9. Multivariable Mendelian randomization: the use of pleiotropic genetic variants to estimate causal effects.

    PubMed

    Burgess, Stephen; Thompson, Simon G

    2015-02-15

    A conventional Mendelian randomization analysis assesses the causal effect of a risk factor on an outcome by using genetic variants that are solely associated with the risk factor of interest as instrumental variables. However, in some cases, such as the case of triglyceride level as a risk factor for cardiovascular disease, it may be difficult to find a relevant genetic variant that is not also associated with related risk factors, such as other lipid fractions. Such a variant is known as pleiotropic. In this paper, we propose an extension of Mendelian randomization that uses multiple genetic variants associated with several measured risk factors to simultaneously estimate the causal effect of each of the risk factors on the outcome. This "multivariable Mendelian randomization" approach is similar to the simultaneous assessment of several treatments in a factorial randomized trial. In this paper, methods for estimating the causal effects are presented and compared using real and simulated data, and the assumptions necessary for a valid multivariable Mendelian randomization analysis are discussed. Subject to these assumptions, we demonstrate that triglyceride-related pathways have a causal effect on the risk of coronary heart disease independent of the effects of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol.

  10. Music during bronchoscopic examination: the physiological effects. A randomized trial.

    PubMed

    Triller, Nadja; Erzen, Damjan; Duh, Stefan; Petrinec Primozic, Marija; Kosnik, Martina

    2006-01-01

    Patients scheduled for bronchoscopic procedures are often anxious and frightened. Reduction in the state of anxiety during an invasive procedure may prevent some possible complications. Music has been proposed as a safe nonpharmacological antianxiety intervention. We followed up physiological indicators of anxiety (blood pressure, heart rate) during bronchoscopic examination to determine the effect of music on the level of anxiety. Two hundred adult patients were included in the study. Blood pressure, heart rate, procedures performed during bronchoscopy and duration of examination were monitored. Patients' overall feelings during the procedure were rated from 0 (without unpleasant feelings) to 10 (unbearable). All patients used the Visual Analogue Scale (VAS). Two hundred adult patients referred for bronchoscopy were included in the study: 93 patients received music during the procedure and 107 served as control. There were no significant differences between the two groups in terms of age, sex, indications for bronchoscopy, procedures performed during bronchoscopy, duration of the examination and patients' subjective perception of the procedure. The mean hart rate, systolic and diastolic blood pressures were significantly lower in the music group compared to the control group. Our findings suggest that the application of music reduces anxiety during bronchoscopic examination as physiological indicators of anxiety, the mean heart rate, systolic and diastolic blood pressures, were significantly lower in the music group. Copyright 2006 S. Karger AG, Basel.

  11. Coherent potential theory of a random binary alloy Effects of scattering from two-sites clusters and off-diagonal randomness

    NASA Technical Reports Server (NTRS)

    Moorjani, K.; Tanaka, T.; Sokoloski, M. M.; Bose, S. M.

    1974-01-01

    Extension of the single-site coherent potential approximation for random binary alloys to include the effect of off-diagonal randomness and pair scattering. This extension is achieved by analyzing a one-band model of a random binary alloy in terms of a two-sites coherent potential approximation. Numerical results are presented for a number of different alloys. In the overlapping-band case, the presence of off-diagonal randomness is shown to modify the bandwidths to values larger than those obtained from the virtual-crystal approximation. A simple iterative procedure is described for overcoming the convergence difficulties in the split-band case. In this limit, the inclusion of pair scattering and off-diagonal randomness is found to lead to the appearance of structure in the density of states of the minority component band.

  12. Randomized controlled trial of the effectiveness of chlorhexidine showers before elective plastic surgical procedures.

    PubMed

    Veiga, Daniela Francescato; Damasceno, Carlos Américo Veiga; Veiga-Filho, Joel; Figueiras, Ricardo Góes; Vieira, Roberto Bezerra; Garcia, Edgard Silva; Silva, Virgínia Vilasboas; Novo, Neil Ferreira; Ferreira, Lydia Masako

    2009-01-01

    This randomized controlled trial was designed to assess the effect of preoperative chlorhexidine showers on skin colonization and postoperative infection rates associated with plastic surgical procedures involving the trunk. Chlorhexidine showers were effective in reducing skin colonization with coagulase-negative staphylococci and yeasts, but there was no difference in postoperative infection rates.

  13. Reconsidering Findings of "No Effects" in Randomized Control Trials: Modeling Differences in Treatment Impacts

    ERIC Educational Resources Information Center

    Chaney, Bradford

    2016-01-01

    The primary technique that many researchers use to analyze data from randomized control trials (RCTs)--detecting the average treatment effect (ATE)--imposes assumptions upon the data that often are not correct. Both theory and past research suggest that treatments may have significant impacts on subgroups even when showing no overall effect.…

  14. Reconsidering Findings of "No Effects" in Randomized Control Trials: Modeling Differences in Treatment Impacts

    ERIC Educational Resources Information Center

    Chaney, Bradford

    2016-01-01

    The primary technique that many researchers use to analyze data from randomized control trials (RCTs)--detecting the average treatment effect (ATE)--imposes assumptions upon the data that often are not correct. Both theory and past research suggest that treatments may have significant impacts on subgroups even when showing no overall effect.…

  15. A Multisite Randomized Effectiveness Trial of Motivational Enhancement Therapy for Spanish-Speaking Substance Users

    ERIC Educational Resources Information Center

    Carroll, Kathleen M.; Martino, Steve; Ball, Samuel A.; Nich, Charla; Frankforter, Tami; Anez, Luis M.; Paris, Manuel; Suarez-Morales, Lourdes; Szapocznik, Jose; Miller, William R.; Rosa, Carmen; Matthews, Julie; Farentinos, Chris

    2009-01-01

    Hispanic individuals are underrepresented in clinical and research populations and are often excluded from clinical trials in the United States. Hence, there are few data on the effectiveness of most empirically validated therapies for Hispanic substance users. The authors conducted a multisite randomized trial comparing the effectiveness of 3…

  16. A Multisite Randomized Effectiveness Trial of Motivational Enhancement Therapy for Spanish-Speaking Substance Users

    ERIC Educational Resources Information Center

    Carroll, Kathleen M.; Martino, Steve; Ball, Samuel A.; Nich, Charla; Frankforter, Tami; Anez, Luis M.; Paris, Manuel; Suarez-Morales, Lourdes; Szapocznik, Jose; Miller, William R.; Rosa, Carmen; Matthews, Julie; Farentinos, Chris

    2009-01-01

    Hispanic individuals are underrepresented in clinical and research populations and are often excluded from clinical trials in the United States. Hence, there are few data on the effectiveness of most empirically validated therapies for Hispanic substance users. The authors conducted a multisite randomized trial comparing the effectiveness of 3…

  17. Random-Effects Models for Meta-Analytic Structural Equation Modeling: Review, Issues, and Illustrations

    ERIC Educational Resources Information Center

    Cheung, Mike W.-L.; Cheung, Shu Fai

    2016-01-01

    Meta-analytic structural equation modeling (MASEM) combines the techniques of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Both fixed-effects and random-effects models can be defined in MASEM.…

  18. The Impact of Five Missing Data Treatments on a Cross-Classified Random Effects Model

    ERIC Educational Resources Information Center

    Hoelzle, Braden R.

    2012-01-01

    The present study compared the performance of five missing data treatment methods within a Cross-Classified Random Effects Model environment under various levels and patterns of missing data given a specified sample size. Prior research has shown the varying effect of missing data treatment options within the context of numerous statistical…

  19. Random-Effects Models for Meta-Analytic Structural Equation Modeling: Review, Issues, and Illustrations

    ERIC Educational Resources Information Center

    Cheung, Mike W.-L.; Cheung, Shu Fai

    2016-01-01

    Meta-analytic structural equation modeling (MASEM) combines the techniques of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Both fixed-effects and random-effects models can be defined in MASEM.…

  20. Longitudinal Achievement Effects of Multiyear Summer School: Evidence from the Teach Baltimore Randomized Field Trial

    ERIC Educational Resources Information Center

    Borman, Geoffrey D.; Dowling, N. Maritza

    2006-01-01

    Employing a randomized field trial, this 3-year study explored the effects of a multiyear summer school program in preventing the cumulative effect of summer learning losses and promoting longitudinal achievement growth, for a total treatment group of 438 students from high-poverty schools. Longitudinal outcomes for the participants were…

  1. A Randomized Effectiveness Trial of Brief Parent Training: Six-Month Follow-Up

    ERIC Educational Resources Information Center

    Kjøbli, John; Bjørnebekk, Gunnar

    2013-01-01

    Objective: To examine the follow-up effectiveness of brief parent training (BPT) for children with emerging or existing conduct problems. Method: With the use of a randomized controlled trial and parent and teacher reports, this study examined the effectiveness of BPT compared to regular services 6 months after the end of the intervention.…

  2. The Impact of Five Missing Data Treatments on a Cross-Classified Random Effects Model

    ERIC Educational Resources Information Center

    Hoelzle, Braden R.

    2012-01-01

    The present study compared the performance of five missing data treatment methods within a Cross-Classified Random Effects Model environment under various levels and patterns of missing data given a specified sample size. Prior research has shown the varying effect of missing data treatment options within the context of numerous statistical…

  3. Transient Adverse Side Effects During Neurofeedback Training: A Randomized, Sham-Controlled, Double Blind Study.

    PubMed

    Rogel, Ainat; Guez, Jonathan; Getter, Nir; Keha, Eldad; Cohen, Tzlil; Amor, Tali; Todder, Doron

    2015-09-01

    The benefits of clinical neurofeedback training are well known, however, its adverse side-effects are less studied. This research focuses on the transient adverse side effects of neurofeedback training via a double-blind, sham/controlled methodology. Thirty healthy undergraduate students volunteers were randomly divided into three treatment groups: increasing a modified Sensory Motor Rhythm, increasing Upper Alpha, and Sham/control group who receive a random reward. The training sessions were administered for a total of ten sessions. Questionnaires of transient adverse side effects were completed by all volunteers before each session. The results suggest that similar to most medical treatments, neurofeedback can cause transient adverse side effects. Moreover, most participants reported experiencing some side effects. The side effects can be divided into non-specific side effect, associated with the neurofeedback training in general and specific ones associated with the particular protocol. Sensory Motor Rhythm protocol seems to be the most sensitive to side effects.

  4. The Effect of the Random Magnetic Field Component on the Parker Instability

    NASA Astrophysics Data System (ADS)

    Kim, Jongsoo; Ryu, Dongsu

    2001-11-01

    The Parker instability is considered to play important roles in the evolution of the interstellar medium. Most studies on the development of the instability so far have been based on an initial equilibrium system with a uniform magnetic field. However, the Galactic magnetic field possesses a random component in addition to the mean uniform component, with comparable strength of the two components. Parker and Jokipii have recently suggested that the random component can suppress the growth of small wavelength perturbations. Here we extend their analysis by including gas pressure, which was ignored in their work, and study the stabilizing effect of the random component in the interstellar gas with finite pressure. Following Parker and Jokipii, we model the magnetic field as a mean azimuthal component, B(z), plus a random radial component, ɛ(z)B(z), where ɛ(z) is a random function of height from the equatorial plane. We show that for the observationally suggested values of <ɛ2>1/2, the tension due to the random component becomes important, so that the growth of the instability is either significantly reduced or completely suppressed. When the instability still works, the radial wavenumber of the most unstable mode is found to be zero. That is, the instability is reduced to be effectively two-dimensional. We discuss briefly the implications of our finding.

  5. Effects of zinc supplementation on subscales of anorexia in children: A randomized controlled trial

    PubMed Central

    Khademian, Majid; Farhangpajouh, Neda; Shahsanaee, Armindokht; Bahreynian, Maryam; Mirshamsi, Mehran; Kelishadi, Roya

    2014-01-01

    Objectives: This study aims to assess the effects of zinc supplementation on improving the appetite and its subscales in children. Methods: This study was conducted in 2013 in Isfahan, Iran. It had two phases. At the first step, after validation of the Child Eating Behaviour Questionaire (CEBQ), it was completed for 300 preschool children, who were randomly selected. The second phase was conducted as a randomized controlled trial. Eighty of these children were randomly selected, and were randomly assigned to two groups of equal number receiving zinc (10 mg/day) or placebo for 12 weeks. Results: Overall 77 children completed the trial (39 in the case and 3 in the control group).The results showed that zinc supplement can improve calorie intake in children by affecting some CEBQ subscales like Emotional over Eating and Food Responsible. Conclusion: Zinc supplementation had positive impact in promoting the calorie intake and some subscales of anorexia. PMID:25674110

  6. Lossless Astronomical Image Compression and the Effects of Random Noise

    NASA Technical Reports Server (NTRS)

    Pence, William

    2009-01-01

    In this paper we compare a variety of modern image compression methods on a large sample of astronomical images. We begin by demonstrating from first principles how the amount of noise in the image pixel values sets a theoretical upper limit on the lossless compression ratio of the image. We derive simple procedures for measuring the amount of noise in an image and for quantitatively predicting how much compression will be possible. We then compare the traditional technique of using the GZIP utility to externally compress the image, with a newer technique of dividing the image into tiles, and then compressing and storing each tile in a FITS binary table structure. This tiled-image compression technique offers a choice of other compression algorithms besides GZIP, some of which are much better suited to compressing astronomical images. Our tests on a large sample of images show that the Rice algorithm provides the best combination of speed and compression efficiency. In particular, Rice typically produces 1.5 times greater compression and provides much faster compression speed than GZIP. Floating point images generally contain too much noise to be effectively compressed with any lossless algorithm. We have developed a compression technique which discards some of the useless noise bits by quantizing the pixel values as scaled integers. The integer images can then be compressed by a factor of 4 or more. Our image compression and uncompression utilities (called fpack and funpack) that were used in this study are publicly available from the HEASARC web site.Users may run these stand-alone programs to compress and uncompress their own images.

  7. A site-holding effect of TiO2 surface hydroxyl in the photocatalytic direct synthesis of 1,1-diethoxyethane from ethanol.

    PubMed

    Zhang, Hongxia; Zhang, Wenqin; Zhao, Min; Yang, Pengju; Zhu, Zhenping

    2017-01-26

    To understand the mechanism of the photocatalytic direct synthesis of 1,1-diethoxyethane (DEE) from ethanol is vital for enhancing the reaction efficiency. Based on photocatalytic data of different phase TiO2 and F-TiO2 catalysts, radical trapping data, and GC-MS data, we proposed a photocatalytic mechanism for the preparation of both DEE in neat ethanol and 2,3-butanediol (2,3-BD) in ethanol-H2O using photocatalytic methods. In neat ethanol, hydroxyl isn't involved in the catalytic cyclic process but hydroxyl has an indirect site-holding effect, thus leading to more hydroxyl groups with higher activity. In ethanol-H2O, although the strong oxidant ˙OH radical is involved, fewer OH groups lead to higher selectivity of 2,3-BD. The interaction of the reactant/solvent with the surface group of the catalyst is important in the activity and selectivity of photocatalytic reactions. This finding gives fundamental insight into the role of TiO2 surface hydroxyl in the photocatalytic dehydrogenation process of alcohols and opens a promising path to obtaining both high selectivity and high conversion in TiO2-based photocatalytic activity.

  8. Effects of psychological therapies in randomized trials and practice-based studies.

    PubMed

    Barkham, Michael; Stiles, William B; Connell, Janice; Twigg, Elspeth; Leach, Chris; Lucock, Mike; Mellor-Clark, John; Bower, Peter; King, Michael; Shapiro, David A; Hardy, Gillian E; Greenberg, Leslie; Angus, Lynne

    2008-11-01

    Randomized trials of the effects of psychological therapies seek internal validity via homogeneous samples and standardized treatment protocols. In contrast, practice-based studies aim for clinical realism and external validity via heterogeneous samples of clients treated under routine practice conditions. We compared indices of treatment effects in these two types of studies. Using published transformation formulas, the Beck Depression Inventory (BDI) scores from five randomized trials of depression (N = 477 clients) were transformed into Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) scores and compared with CORE-OM data collected in four practice-based studies (N = 4,196 clients). Conversely, the practice-based studies' CORE-OM scores were transformed into BDI scores and compared with randomized trial data. Randomized trials showed a modest advantage over practice-based studies in amount of pre-post improvement. This difference was compressed or exaggerated depending on the direction of the transformation but averaged about 12%. There was a similarly sized advantage to randomized trials in rates of reliable and clinically significant improvement (RCSI). The largest difference was yielded by comparisons of effect sizes which suggested an advantage more than twice as large, reflecting narrower pre-treatment distributions in the randomized trials. Outcomes of completed treatments for depression in randomized trials appeared to be modestly greater than those in routine care settings. The size of the difference may be distorted depending on the method for calculating degree of change. Transforming BDI scores into CORE-OM scores and vice versa may be a preferable alternative to effect sizes for comparisons of studies using these measures.

  9. Joint modeling of survival time and longitudinal outcomes with flexible random effects.

    PubMed

    Choi, Jaeun; Zeng, Donglin; Olshan, Andrew F; Cai, Jianwen

    2017-08-30

    Joint models with shared Gaussian random effects have been conventionally used in analysis of longitudinal outcome and survival endpoint in biomedical or public health research. However, misspecifying the normality assumption of random effects can lead to serious bias in parameter estimation and future prediction. In this paper, we study joint models of general longitudinal outcomes and survival endpoint but allow the underlying distribution of shared random effect to be completely unknown. For inference, we propose to use a mixture of Gaussian distributions as an approximation to this unknown distribution and adopt an Expectation-Maximization (EM) algorithm for computation. Either AIC and BIC criteria are adopted for selecting the number of mixtures. We demonstrate the proposed method via a number of simulation studies. We illustrate our approach with the data from the Carolina Head and Neck Cancer Study (CHANCE).

  10. Effects of introducing nonlinear components for a random excited hybrid energy harvester

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoya; Gao, Shiqiao; Liu, Haipeng; Guan, Yanwei

    2017-01-01

    This work is mainly devoted to discussing the effects of introducing nonlinear components for a hybrid energy harvester under random excitation. For two different types of nonlinear hybrid energy harvesters subjected to random excitation, the analytical solutions of the mean output power, voltage and current are derived from Fokker-Planck (FP) equations. Monte Carlo simulation exhibits qualitative agreement with FP theory, showing that load values and excitation’s spectral density have an effect on the total mean output power, piezoelectric (PE) power and electromagnetic power. Nonlinear components affect output characteristics only when the PE capacitance of the hybrid energy harvester is non-negligible. Besides, it is also demonstrated that for this type of nonlinear hybrid energy harvesters under random excitation, introducing nonlinear components can improve output performances effectively.

  11. Bounds on the average causal effects in randomized trials with noncompliance by covariate adjustment.

    PubMed

    Shan, Na; Xu, Ping-Feng

    2016-11-01

    In randomized trials with noncompliance, causal effects cannot be identified without strong assumptions. Therefore, several authors have considered bounds on the causal effects. Applying an idea of VanderWeele (), Chiba () gave bounds on the average causal effects in randomized trials with noncompliance using the information on the randomized assignment, the treatment received and the outcome under monotonicity assumptions about covariates. But he did not consider any observed covariates. If there are some observed covariates such as age, gender, and race in a trial, we propose new bounds using the observed covariate information under some monotonicity assumptions similar to those of VanderWeele and Chiba. And we compare the three bounds in a real example. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Defining a clinically meaningful effect for the design and interpretation of randomized controlled trials.

    PubMed

    Keefe, Richard S E; Kraemer, Helena C; Epstein, Robert S; Frank, Ellen; Haynes, Ginger; Laughren, Thomas P; McNulty, James; Reed, Shelby D; Sanchez, Juan; Leon, Andrew C

    2013-05-01

    This article captures the proceedings of a meeting aimed at defining clinically meaningful effects for use in randomized controlled trials for psychopharmacological agents. Experts from a variety of disciplines defined clinically meaningful effects from their perspectives along with viewpoints about how to design and interpret randomized controlled trials. The article offers relevant, practical, and sometimes anecdotal information about clinically meaningful effects and how to interpret them. The concept for this session was the work of co-chairs Richard Keefe and the late Andy Leon. Faculty included Richard Keefe, PhD; James McNulty, AbScB; Robert S. Epstein, MD, MS; Shelby D. Reed, PhD; Juan Sanchez, MD; Ginger Haynes, PhD; Andrew C. Leon, PhD; Helena Chmura Kraemer, PhD; Ellen Frank, PhD, and Kenneth L. Davis, MD. The term clinically meaningful effect is an important aspect of designing and interpreting randomized controlled trials but can be particularly difficult in the setting of psychopharmacology where effect size may be modest, particularly over the short term, because of a strong response to placebo. Payers, regulators, patients, and clinicians have different concerns about clinically meaningful effects and may describe these terms differently. The use of moderators in success rate differences may help better delineate clinically meaningful effects. There is no clear consensus on a single definition for clinically meaningful differences in randomized controlled trials, and investigators must be sensitive to specific concerns of stakeholders in psychopharmacology in order to design and execute appropriate clinical trials.

  13. Effects of low-level radioactive-waste disposal on water chemistry in the unsaturated zone at a site near Sheffield, Illinois, 1982-84

    USGS Publications Warehouse

    Peters, C.A.; Striegl, R.G.; Mills, P.C.; Healy, R.W.

    1992-01-01

    A 1982-84 field study defined the chemistry of water collected from the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois. Chemical data were evaluated to determine the principal naturally occurring geochemical reactions in the unsaturated zone and to evaluate waste-induced effects on pore-water chemistry. Samples of precipitation, unsaturated-zone pore water, and saturated-zone water were analyzed for specific conductance, pH, alkalinity, major cations and anions, dissolved organic carbon, gross alpha and beta radiation, and tritium. Little change in concentration of most major constituents in the unsaturated-zone water was observed with respect to depth or distance from disposal trenches. Tritium and dissolved organic carbon concentrations were, however, dependent on proximity to trenches. The primary reactions, both on- site and off-site, were carbonate and clay dissolution, cation exchange, and the oxidation of pyrite. The major difference between on-site and off-site inorganic water chemistry resulted from the removal of the Roxana Silt and the Radnor Till Member of the Glasford Formation from on-site. Off-site, the Roxana Silt contributed substantial quantities of sodium to solution from montmorillonite dissolution and associated cation-exchange reactions. The Radnor Till Member provided exchange surfaces for magnesium. Precipitation at the site had an ionic composition of calcium zinc sulfate and an average pH of 4.6. Within 0.3 meter of the land surface, infiltrating rain water or snowmelt changed to an ionic canposition of calcium sulfate off-site and calcium bicarbonate on-site and had an average pH of 7.9; below that depth, pH averaged 7.5 and the ionic composition generally was calcium magnesium bicarbonate. Alkalinity and specific conductance differed primarily according to composition of geologic materials. Tritium concentrations ranged from 0.2 (detection limit) to 1,380 nanocuries per liter. The

  14. Effects of low-level radioactive-waste disposal on water chemistry in the unsaturated zone at a site near Sheffield, Illinois, 1982-84

    USGS Publications Warehouse

    Peters, C.A.; Striegl, R.G.; Mills, P.C.; Healy, R.W.

    1992-01-01

    A 1982-84 field study defined the chemistry of water collected from the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Ill. Chemical data were evaluated to determine the principal, naturally occurring geochemical reactions in the unsaturated zone and to evaluate waste-induced effects on pore-water chemistry. Samples of precipitation, unsaturated-zone pore water, and saturated-zone water were analyzed for specific conductance, pH, alkalinity, major cations and anions, dissolved organic carbon, gross alpha and beta radiation, and tritium. Little change in concentration of most major constituents in the unsaturated-zone water was observed with respect to depth or distance from disposal trenches. Tritium and dissolved organic carbon concentrations were, however, dependent on proximity to trenches. The primary reactions, both on-site and off-site, were carbonate and clay dissolution, cation exchange, and the oxidation of pyrite. The major difference between on-site and off-site inorganic water chemistry resulted from the removal of the Roxana Silt and the Radnor Till Member of the Glasford Formation from on-site. Off-site, the Roxana Silt contributed substantial quantities of sodium to solution from montmorillonite dissolution and associated cation-exchange reactions. The Radnor Till Member provided exchange surfaces for magnesium. Precipitation at the site had an ionic composition of calcium zinc sulfate and an average pH of 4.6. Within 0.3 meter of the land surface, infiltrating rainwater or snowmelt changed to an ionic composition of calcium sulfate off-site and calcium bicarbonate on-site and had an average pH of 7.9; below that depth, pH averaged 7.5 and the ionic composition generally was calcium magnesium bicarbonate. Alkalinity and specific conductance differed primarily according to composition of geologic materials. Tritium concentrations ranged from 0.2 (detection limit) to 1,380 nanocuries per liter. The

  15. Heterogeneous Suppression of Sequential Effects in Random Sequence Generation, but Not in Operant Learning

    PubMed Central

    Shteingart, Hanan; Loewenstein, Yonatan

    2016-01-01

    There is a long history of experiments in which participants are instructed to generate a long sequence of binary random numbers. The scope of this line of research has shifted over the years from identifying the basic psychological principles and/or the heuristics that lead to deviations from randomness, to one of predicting future choices. In this paper, we used generalized linear regression and the framework of Reinforcement Learning in order to address both points. In particular, we used logistic regression analysis in order to characterize the temporal sequence of participants’ choices. Surprisingly, a population analysis indicated that the contribution of the most recent trial has only a weak effect on behavior, compared to more preceding trials, a result that seems irreconcilable with standard sequential effects that decay monotonously with the delay. However, when considering each participant separately, we found that the magnitudes of the sequential effect are a monotonous decreasing function of the delay, yet these individual sequential effects are largely averaged out in a population analysis because of heterogeneity. The substantial behavioral heterogeneity in this task is further demonstrated quantitatively by considering the predictive power of the model. We show that a heterogeneous model of sequential dependencies captures the structure available in random sequence generation. Finally, we show that the results of the logistic regression analysis can be interpreted in the framework of reinforcement learning, allowing us to compare the sequential effects in the random sequence generation task to those in an operant learning task. We show that in contrast to the random sequence generation task, sequential effects in operant learning are far more homogenous across the population. These results suggest that in the random sequence generation task, different participants adopt different cognitive strategies to suppress sequential dependencies when

  16. Logistic random effects regression models: a comparison of statistical packages for binary and ordinal outcomes

    PubMed Central

    2011-01-01

    Background Logistic random effects models are a popular tool to analyze multilevel also called hierarchical data with a binary or ordinal outcome. Here, we aim to compare different statistical software implementations of these models. Methods We used individual patient data from 8509 patients in 231 centers with moderate and severe Traumatic Brain Injury (TBI) enrolled in eight Randomized Controlled Trials (RCTs) and three observational studies. We fitted logistic random effects regression models with the 5-point Glasgow Outcome Scale (GOS) as outcome, both dichotomized as well as ordinal, with center and/or trial as random effects, and as covariates age, motor score, pupil reactivity or trial. We then compared the implementations of frequentist and Bayesian methods to estimate the fixed and random effects. Frequentist approaches included R (lme4), Stata (GLLAMM), SAS (GLIMMIX and NLMIXED), MLwiN ([R]IGLS) and MIXOR, Bayesian approaches included WinBUGS, MLwiN (MCMC), R package MCMCglmm and SAS experimental procedure MCMC. Three data sets (the full data set and two sub-datasets) were analysed using basically two logistic random effects models with either one random effect for the center or two random effects for center and trial. For the ordinal outcome in the full data set also a proportional odds model with a random center effect was fitted. Results The packages gave similar parameter estimates for both the fixed and random effects and for the binary (and ordinal) models for the main study and when based on a relatively large number of level-1 (patient level) data compared to the number of level-2 (hospital level) data. However, when based on relatively sparse data set, i.e. when the numbers of level-1 and level-2 data units were about the same, the frequentist and Bayesian approaches showed somewhat different results. The software implementations differ considerably in flexibility, computation time, and usability. There are also differences in the availability

  17. Random exchange interaction effects on the phase transitions in frustrated classical Heisenberg model

    SciTech Connect

    Li, W. C.; Song, X.; Feng, J. J.; Zeng, M.; Gao, X. S.; Qin, M. H.; Jia, X. T.

    2015-07-07

    In this work, the effects of the random exchange interaction on the phase transitions and phase diagrams of classical frustrated Heisenberg model are investigated by Monte Carlo simulation in order to simulate the chemical doping effect in real materials. It is observed that the antiferromagnetic transitions shift toward low temperature with the increasing magnitude of the random exchange interaction, which can be qualitatively understood from the competitions among local spin states. This study is related to the magnetic properties in the doped iron-based superconductors.

  18. Network meta-analysis of disconnected networks: How dangerous are random baseline treatment effects?

    PubMed

    Béliveau, Audrey; Goring, Sarah; Platt, Robert W; Gustafson, Paul

    2017-07-24

    In network meta-analysis, the use of fixed baseline treatment effects (a priori independent) in a contrast-based approach is regularly preferred to the use of random baseline treatment effects (a priori dependent). That is because, often, there is not a need to model baseline treatment effects, which carry the risk of model misspecification. However, in disconnected networks, fixed baseline treatment effects do not work (unless extra assumptions are made), as there is not enough information in the data to update the prior distribution on the contrasts between disconnected treatments. In this paper, we investigate to what extent the use of random baseline treatment effects is dangerous in disconnected networks. We take 2 publicly available datasets of connected networks and disconnect them in multiple ways. We then compare the results of treatment comparisons obtained from a Bayesian contrast-based analysis of each disconnected network using random normally distributed and exchangeable baseline treatment effects to those obtained from a Bayesian contrast-based analysis of their initial connected network using fixed baseline treatment effects. For the 2 datasets considered, we found that the use of random baseline treatment effects in disconnected networks was appropriate. Because those datasets were not cherry-picked, there should be other disconnected networks that would benefit from being analyzed using random baseline treatment effects. However, there is also a risk for the normality and exchangeability assumption to be inappropriate in other datasets even though we have not observed this situation in our case study. We provide code, so other datasets can be investigated. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Random Process Theory Approach to Geometric Heterogeneous Surfaces: Effective Fluid-Solid Interaction

    NASA Astrophysics Data System (ADS)

    Khlyupin, Aleksey; Aslyamov, Timur

    2017-06-01

    Realistic fluid-solid interaction potentials are essential in description of confined fluids especially in the case of geometric heterogeneous surfaces. Correlated random field is considered as a model of random surface with high geometric roughness. We provide the general theory of effective coarse-grained fluid-solid potential by proper averaging of the free energy of fluid molecules which interact with the solid media. This procedure is largely based on the theory of random processes. We apply first passage time probability problem and assume the local Markov properties of random surfaces. General expression of effective fluid-solid potential is obtained. In the case of small surface irregularities analytical approximation for effective potential is proposed. Both amorphous materials with large surface roughness and crystalline solids with several types of fcc lattices are considered. It is shown that the wider the lattice spacing in terms of molecular diameter of the fluid, the more obtained potentials differ from classical ones. A comparison with published Monte-Carlo simulations was discussed. The work provides a promising approach to explore how the random geometric heterogeneity affects on thermodynamic properties of the fluids.

  20. Modeling zero-inflated count data using a covariate-dependent random effect model.

    PubMed

    Wong, Kin-Yau; Lam, K F

    2013-04-15

    In various medical related researches, excessive zeros, which make the standard Poisson regression model inadequate, often exist in count data. We proposed a covariate-dependent random effect model to accommodate the excess zeros and the heterogeneity in the population simultaneously. This work is motivated by a data set from a survey on the dental health status of Hong Kong preschool children where the response variable is the number of decayed, missing, or filled teeth. The random effect has a sound biological interpretation as the overall oral health status or other personal qualities of an individual child that is unobserved and unable to be quantified easily. The overall measure of oral health status, responsible for accommodating the excessive zeros and also the heterogeneity among the children, is covariate dependent. This covariate-dependent random effect model allows one to distinguish whether a potential covariate has an effect on the conceived overall oral health condition of the children, that is, the random effect, or has a direct effect on the magnitude of the counts, or both. We proposed a multiple imputation approach for estimation of the parameters. We discussed the choice of the imputation size. We evaluated the performance of the proposed estimation method through simulation studies, and we applied the model and method to the dental data.

  1. Predicting longitudinal trajectories of health probabilities with random-effects multinomial logit regression.

    PubMed

    Liu, Xian; Engel, Charles C

    2012-12-20

    Researchers often encounter longitudinal health data characterized with three or more ordinal or nominal categories. Random-effects multinomial logit models are generally applied to account for potential lack of independence inherent in such clustered data. When parameter estimates are used to describe longitudinal processes, however, random effects, both between and within individuals, need to be retransformed for correctly predicting outcome probabilities. This study attempts to go beyond existing work by developing a retransformation method that derives longitudinal growth trajectories of unbiased health probabilities. We estimated variances of the predicted probabilities by using the delta method. Additionally, we transformed the covariates' regression coefficients on the multinomial logit function, not substantively meaningful, to the conditional effects on the predicted probabilities. The empirical illustration uses the longitudinal data from the Asset and Health Dynamics among the Oldest Old. Our analysis compared three sets of the predicted probabilities of three health states at six time points, obtained from, respectively, the retransformation method, the best linear unbiased prediction, and the fixed-effects approach. The results demonstrate that neglect of retransforming random errors in the random-effects multinomial logit model results in severely biased longitudinal trajectories of health probabilities as well as overestimated effects of covariates on the probabilities. Copyright © 2012 John Wiley & Sons, Ltd.

  2. Effect of random field disorder on the first order transition in p-spin interaction model

    NASA Astrophysics Data System (ADS)

    Sumedha; Singh, Sushant K.

    2016-01-01

    We study the random field p-spin model with Ising spins on a fully connected graph using the theory of large deviations in this paper. This is a good model to study the effect of quenched random field on systems which have a sharp first order transition in the pure state. For p = 2, the phase-diagram of the model, for bimodal distribution of the random field, has been well studied and is known to undergo a continuous transition for lower values of the random field (h) and a first order transition beyond a threshold, htp(≈ 0.439) . We find the phase diagram of the model, for all p ≥ 2, with bimodal random field distribution, using large deviation techniques. We also look at the fluctuations in the system by calculating the magnetic susceptibility. For p = 2, beyond the tricritical point in the regime of first order transition, we find that for htp < h < 0.447, magnetic susceptibility increases rapidly (even though it never diverges) as one approaches the transition from the high temperature side. On the other hand, for 0.447 < h ≤ 0.5, the high temperature behaviour is well described by the Curie-Weiss law. For all p ≥ 2, we find that for larger magnitudes of the random field (h >ho = 1 / p!), the system does not show ferromagnetic order even at zero temperature. We find that the magnetic susceptibility for p ≥ 3 is discontinuous at the transition point for h

  3. The effect of random modulation of functional electrical stimulation parameters on muscle fatigue.

    PubMed

    Graham, Geoffrey M; Thrasher, T Adam; Popovic, Milos R

    2006-03-01

    Muscle contractions induced by functional electrical stimulation (FES) tend to result in rapid muscle fatigue, which greatly limits activities such as FES-assisted standing and walking. It was hypothesized that muscle fatigue caused by FES could be reduced by randomly modulating parameters of the electrical stimulus. Seven paraplegic subjects participated in this study. While subjects were seated, FES was applied to quadriceps and tibialis anterior muscles bilaterally using surface electrodes. The isometric force was measured, and the time for the force to drop by 3 dB (fatigue time) and the normalized force-time integral (FTI) were determined. Four different modes of FES were applied in random order: constant stimulation, randomized frequency (mean 40 Hz), randomized current amplitude, and randomized pulsewidth (mean 250 micros). In randomized trials, stimulation parameters were stochastically modulated every 100 ms in a range of +/-15% using a uniform probability distribution. There was no significant difference between the fatigue time measurements for the four modes of stimulation. There was also no significant difference in the FTI measurements. Therefore, our particular method of stochastic modulation of the stimulation parameters, which involved moderate (15%) variations updated every 100 ms and centered around 40 Hz, appeared to have no effect on muscle fatigue. There was a strong correlation between maximum force measurements and stimulation order, which was not apparent in the fatigue time or FTI measurements. It was concluded that a 10-min rest period between stimulation trials was insufficient to allow full recovery of muscle strength.

  4. Effective conductivity of particulate polymer composite electrolytes using random resistor network method

    SciTech Connect

    Kalnaus, Sergiy; Sabau, Adrian S; Newman, Sarah M; Tenhaeff, Wyatt E; Daniel, Claus; Dudney, Nancy J

    2011-01-01

    The effective DC conductivity of particulate composite electrolytes was obtained by solving electrostatics equations using random resistors network method in three dimensions. The composite structure was considered to consist of three phases: matrix, particulate filler, and conductive shell that surrounded each particle; each phase possessing a different conductivity. Different particle size distributions were generated using Monte Carlo simulations. Unlike effective medium formulations, it was shown that the random resistors network method was able to predict percolation thresholds for the effective composite conductivity. It was found that the mean particle radius has a higher influence on the effective composite conductivity compared to the effect of type of the particle size distributions that were considered. The effect of the shell thickness on the composite conductivity has been investigated. It was found that the conductivity enhancement due to the presence of the conductive shell phase becomes less evident as the shell thickness increases.

  5. Derivation of predicted no effect concentrations (PNEC) for marine environmental risk assessment: application of different approaches to the model contaminant Linear Alkylbenzene Sulphonates (LAS) in a site-specific environment.

    PubMed

    Hampel, M; González-Mazo, E; Vale, C; Blasco, J

    2007-05-01

    Four sediment-dwelling marine organisms were exposed to sediments spiked with increasing concentrations of Linear Alkylbenzene Sulphonate (LAS). The selected endpoint mortality was reported daily and acute LC(50) (96 h), as well as final LC(10) values were calculated for the derivation of environmentally safe predicted no effect concentrations (PNEC) for the sediment compartment. PNECs were estimated by both application of assessment factors (AF) and the equilibrium partitioning method (EPM) as proposed by the EU TGD. Finally, environmental risk assessment in a site-specific environment, the Sancti Petri Channel, South Iberian Peninsula, was carried out at three different sampling stations with known environmental LAS concentrations. PNECs obtained by the assessment factor approach with acute toxicity data were one to two orders of magnitude lower than those from the equilibrium partitioning method. On the other hand, when applying lower AFs to the estimated LC(10) values, the PNECs obtained by both approaches were more similar. Environmental risk assessment carried out with the estimated PNECs in a site specific environment with known sediment LAS concentrations revealed that PNECs obtained with acute toxicity data were over conservative whereas those obtained with AF=10 on LC(10) data and EPM produced more realistic results in accordance with field observations carried out in the study area.

  6. The effective density of randomly moving electrons and related characteristics of materials with degenerate electron gas

    SciTech Connect

    Palenskis, V.

    2014-04-15

    Interpretation of the conductivity of metals, of superconductors in the normal state and of semiconductors with highly degenerate electron gas remains a significant issue if consideration is based on the classical statistics. This study is addressed to the characterization of the effective density of randomly moving electrons and to the evaluation of carrier diffusion coefficient, mobility, and other parameters by generalization of the widely published experimental results. The generalized expressions have been derived for various kinetic parameters attributed to the non-degenerate and degenerate electron gas, by analyzing a random motion of the single type carriers in homogeneous materials. The values of the most important kinetic parameters for different metals are also systematized and discussed. It has been proved that Einstein's relation between the diffusion coefficient and the drift mobility of electrons is held for any level of degeneracy if the effective density of randomly moving carriers is properly taken into account.

  7. How large are the nonspecific effects of acupuncture? A meta-analysis of randomized controlled trials

    PubMed Central

    2010-01-01

    Background While several recent large randomized trials found clinically relevant effects of acupuncture over no treatment or routine care, blinded trials comparing acupuncture to sham interventions often reported only minor or no differences. This raises the question whether (sham) acupuncture is associated with particularly potent nonspecific effects. We aimed to investigate the size of nonspecific effects associated with acupuncture interventions. Methods MEDLINE, Embase, Cochrane Central Register of Controlled Clinical Trials and reference lists were searched up to April 2010 to identify randomized trials of acupuncture for any condition, including both sham and no acupuncture control groups. Data were extracted by one reviewer and verified by a second. Pooled standardized mean differences were calculated using a random effects model with the inverse variance method. Results Thirty-seven trials with a total of 5754 patients met the inclusion criteria. The included studies varied strongly regarding patients, interventions, outcome measures, methodological quality and effect sizes reported. Among the 32 trials reporting a continuous outcome measure, the random effects standardized mean difference between sham acupuncture and no acupuncture groups was -0.45 (95% confidence interval, -0.57, -0.34; I2 = 54%; Egger's test for funnel plot asymmetry, P = 0.25). Trials with larger effects of sham over no acupuncture reported smaller effects of acupuncture over sham intervention than trials with smaller nonspecific effects (β = -0.39, P = 0.029). Conclusions Sham acupuncture interventions are often associated with moderately large nonspecific effects which could make it difficult to detect small additional specific effects. Compared to inert placebo interventions, effects associated with sham acupuncture might be larger, which would have considerable implications for the design and interpretation of clinical trials. PMID:21092261

  8. Random forests as cumulative effects models: A case study of lakes and rivers in Muskoka, Canada.

    PubMed

    Jones, F Chris; Plewes, Rachel; Murison, Lorna; MacDougall, Mark J; Sinclair, Sarah; Davies, Christie; Bailey, John L; Richardson, Murray; Gunn, John

    2017-10-01

    Cumulative effects assessment (CEA) - a type of environmental appraisal - lacks effective methods for modeling cumulative effects, evaluating indicators of ecosystem condition, and exploring the likely outcomes of development scenarios. Random forests are an extension of classification and regression trees, which model response variables by recursive partitioning. Random forests were used to model a series of candidate ecological indicators that described lakes and rivers from a case study watershed (The Muskoka River Watershed, Canada). Suitability of the candidate indicators for use in cumulative effects assessment and watershed monitoring was assessed according to how well they could be predicted from natural habitat features and how sensitive they were to human land-use. The best models explained 75% of the variation in a multivariate descriptor of lake benthic-macroinvertebrate community structure, and 76% of the variation in the conductivity of river water. Similar results were obtained by cross-validation. Several candidate indicators detected a simulated doubling of urban land-use in their catchments, and a few were able to detect a simulated doubling of agricultural land-use. The paper demonstrates that random forests can be used to describe the combined and singular effects of multiple stressors and natural environmental factors, and furthermore, that random forests can be used to evaluate the performance of monitoring indicators. The numerical methods presented are applicable to any ecosystem and indicator type, and therefore represent a step forward for CEA. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  9. Multivariable Mendelian Randomization: The Use of Pleiotropic Genetic Variants to Estimate Causal Effects

    PubMed Central

    Burgess, Stephen; Thompson, Simon G.

    2015-01-01

    A conventional Mendelian randomization analysis assesses the causal effect of a risk factor on an outcome by using genetic variants that are solely associated with the risk factor of interest as instrumental variables. However, in some cases, such as the case of triglyceride level as a risk factor for cardiovascular disease, it may be difficult to find a relevant genetic variant that is not also associated with related risk factors, such as other lipid fractions. Such a variant is known as pleiotropic. In this paper, we propose an extension of Mendelian randomization that uses multiple genetic variants associated with several measured risk factors to simultaneously estimate the causal effect of each of the risk factors on the outcome. This “multivariable Mendelian randomization” approach is similar to the simultaneous assessment of several treatments in a factorial randomized trial. In this paper, methods for estimating the causal effects are presented and compared using real and simulated data, and the assumptions necessary for a valid multivariable Mendelian randomization analysis are discussed. Subject to these assumptions, we demonstrate that triglyceride-related pathways have a causal effect on the risk of coronary heart disease independent of the effects of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. PMID:25632051

  10. Logistic Regression with Multiple Random Effects: A Simulation Study of Estimation Methods and Statistical Packages

    PubMed Central

    Kim, Yoonsang; Emery, Sherry

    2013-01-01

    Several statistical packages are capable of estimating generalized linear mixed models and these packages provide one or more of three estimation methods: penalized quasi-likelihood, Laplace, and Gauss-Hermite. Many studies have investigated these methods’ performance for the mixed-effects logistic regression model. However, the authors focused on models with one or two random effects and assumed a simple covariance structure between them, which may not be realistic. When there are multiple correlated random effects in a model, the computation becomes intensive, and often an algorithm fails to converge. Moreover, in our analysis of smoking status and exposure to anti-tobacco advertisements, we have observed that when a model included multiple random effects, parameter estimates varied considerably from one statistical package to another even when using the same estimation method. This article presents a comprehensive review of the advantages and disadvantages of each estimation method. In addition, we compare the performances of the three methods across statistical packages via simulation, which involves two- and three-level logistic regression models with at least three correlated random effects. We apply our findings to a real dataset. Our results suggest that two packages—SAS GLIMMIX Laplace and SuperMix Gaussian quadrature—perform well in terms of accuracy, precision, convergence rates, and computing speed. We also discuss the strengths and weaknesses of the two packages in regard to sample sizes. PMID:24288415

  11. Logistic Regression with Multiple Random Effects: A Simulation Study of Estimation Methods and Statistical Packages.

    PubMed

    Kim, Yoonsang; Choi, Young-Ku; Emery, Sherry

    2013-08-01

    Several statistical packages are capable of estimating generalized linear mixed models and these packages provide one or more of three estimation methods: penalized quasi-likelihood, Laplace, and Gauss-Hermite. Many studies have investigated these methods' performance for the mixed-effects logistic regression model. However, the authors focused on models with one or two random effects and assumed a simple covariance structure between them, which may not be realistic. When there are multiple correlated random effects in a model, the computation becomes intensive, and often an algorithm fails to converge. Moreover, in our analysis of smoking status and exposure to anti-tobacco advertisements, we have observed that when a model included multiple random effects, parameter estimates varied considerably from one statistical package to another even when using the same estimation method. This article presents a comprehensive review of the advantages and disadvantages of each estimation method. In addition, we compare the performances of the three methods across statistical packages via simulation, which involves two- and three-level logistic regression models with at least three correlated random effects. We apply our findings to a real dataset. Our results suggest that two packages-SAS GLIMMIX Laplace and SuperMix Gaussian quadrature-perform well in terms of accuracy, precision, convergence rates, and computing speed. We also discuss the strengths and weaknesses of the two packages in regard to sample sizes.

  12. A Bayesian comparative effectiveness trial in action: developing a platform for multisite study adaptive randomization.

    PubMed

    Brown, Alexandra R; Gajewski, Byron J; Aaronson, Lauren S; Mudaranthakam, Dinesh Pal; Hunt, Suzanne L; Berry, Scott M; Quintana, Melanie; Pasnoor, Mamatha; Dimachkie, Mazen M; Jawdat, Omar; Herbelin, Laura; Barohn, Richard J

    2016-08-31

    In the last few decades, the number of trials using Bayesian methods has grown rapidly. Publications prior to 1990 included only three clinical trials that used Bayesian methods, but that number quickly jumped to 19 in the 1990s and to 99 from 2000 to 2012. While this literature provides many examples of Bayesian Adaptive Designs (BAD), none of the papers that are available walks the reader through the detailed process of conducting a BAD. This paper fills that gap by describing the BAD process used for one comparative effectiveness trial (Patient Assisted Intervention for Neuropathy: Comparison of Treatment in Real Life Situations) that can be generalized for use by others. A BAD was chosen with efficiency in mind. Response-adaptive randomization allows the potential for substantially smaller sample sizes, and can provide faster conclusions about which treatment or treatments are most effective. An Internet-based electronic data capture tool, which features a randomization module, facilitated data capture across study sites and an in-house computation software program was developed to implement the response-adaptive randomization. A process for adapting randomization with minimal interruption to study sites was developed. A new randomization table can be generated quickly and can be seamlessly integrated in the data capture tool with minimal interruption to study sites. This manuscript is the first to detail the technical process used to evaluate a multisite comparative effectiveness trial using adaptive randomization. An important opportunity for the application of Bayesian trials is in comparative effectiveness trials. The specific case study presented in this paper can be used as a model for conducting future clinical trials using a combination of statistical software and a web-based application. ClinicalTrials.gov Identifier: NCT02260388 , registered on 6 October 2014.

  13. Analysis of an incomplete longitudinal composite variable using a marginalized random effects model and multiple imputation.

    PubMed

    Gosho, Masahiko; Maruo, Kazushi; Ishii, Ryota; Hirakawa, Akihiro

    2016-11-16

    The total score, which is calculated as the sum of scores in multiple items or questions, is repeatedly measured in longitudinal clinical studies. A mixed effects model for repeated measures method is often used to analyze these data; however, if one or more individual items are not measured, the method cannot be directly applied to the total score. We develop two simple and interpretable procedures that infer fixed effects for a longitudinal continuous composite variable. These procedures consider that the items that compose the total score are multivariate longitudinal continuous data and, simultaneously, handle subject-level and item-level missing data. One procedure is based on a multivariate marginalized random effects model with a multiple of Kronecker product covariance matrices for serial time dependence and correlation among items. The other procedure is based on a multiple imputation approach with a multivariate normal model. In terms of the type-1 error rate and the bias of treatment effect in total score, the marginalized random effects model and multiple imputation procedures performed better than the standard mixed effects model for repeated measures analysis with listwise deletion and single imputations for handling item-level missing data. In particular, the mixed effects model for repeated measures with listwise deletion resulted in substantial inflation of the type-1 error rate. The marginalized random effects model and multiple imputation methods provide for a more efficient analysis by fully utilizing the partially available data, compared to the mixed effects model for repeated measures method with listwise deletion.

  14. A flash-drag effect in random motion reveals involvement of preattentive motion processing

    PubMed Central

    Fukiage, Taiki; Whitney, David; Murakami, Ikuya

    2013-01-01

    The flash-drag (FDE) effect refers to the phenomenon in which the position of a stationary flashed object in one location appears shifted in the direction of nearby motion. Over the past decade, it has been debated how bottom-up and top-down processes contribute to this illusion. In this study, we demonstrate that randomly phase-shifting gratings can produce the FDE. In the random motion sequence we used, the FDE inducer (a sinusoidal grating) jumped to a random phase every 125 ms and stood still until the next jump. Because this random sequence could not be tracked attentively, it was impossible for the observer to discern the jump direction at the time of the flash. By sorting the data based on the flash’s onset time relative to each jump time in the random motion sequence, we found that a large FDE with a broad temporal tuning occurred around 50 to 150 ms before the jump and that this effect was not correlated with any other jumps in the past or future. These results suggest that as few as two frames of unpredictable apparent motion can preattentively cause the FDE with a broad temporal tuning. PMID:22080448

  15. A flash-drag effect in random motion reveals involvement of preattentive motion processing.

    PubMed

    Fukiage, Taiki; Whitney, David; Murakami, Ikuya

    2011-11-11

    The flash-drag (FDE) effect refers to the phenomenon in which the position of a stationary flashed object in one location appears shifted in the direction of nearby motion. Over the past decade, it has been debated how bottom-up and top-down processes contribute to this illusion. In this study, we demonstrate that randomly phase-shifting gratings can produce the FDE. In the random motion sequence we used, the FDE inducer (a sinusoidal grating) jumped to a random phase every 125 ms and stood still until the next jump. Because this random sequence could not be tracked attentively, it was impossible for the observer to discern the jump direction at the time of the flash. By sorting the data based on the flash's onset time relative to each jump time in the random motion sequence, we found that a large FDE with a broad temporal tuning occurred around 50 to 150 ms before the jump and that this effect was not correlated with any other jumps in the past or future. These results suggest that as few as two frames of unpredictable apparent motion can preattentively cause the FDE with a broad temporal tuning.

  16. Treatment effects in randomized longitudinal trials with different types of nonignorable dropout.

    PubMed

    Yang, Manshu; Maxwell, Scott E

    2014-06-01

    Randomized longitudinal designs are commonly used in psychological and medical studies to investigate the treatment effect of an intervention or an experimental drug. Traditional linear mixed-effects models for randomized longitudinal designs are limited to maximum-likelihood methods that assume data are missing at random (MAR). In practice, because longitudinal data are often likely to be missing not at random (MNAR), the traditional mixed-effects model might lead to biased estimates of treatment effects. In such cases, an alternative approach is to utilize pattern-mixture models. In this article, a Monte Carlo simulation study compares the traditional mixed-effects model and 2 different approaches to pattern-mixture models (i.e., the differencing-averaging method and the averaging-differencing method) across different missing mechanisms (i.e., MAR, random-coefficient-dependent MNAR, or outcome-dependent MNAR) and different types of treatment-condition-based missingness. Results suggest that the traditional mixed-effects model is well suited for analyzing data with the MAR mechanism whereas the proposed pattern-mixture averaging-differencing model has the best overall performance for analyzing data with the MNAR mechanism. No method was found that could provide unbiased estimates under every missing mechanism, leading to a practical suggestion that researchers need to consider why data are missing and should also consider performing a sensitivity analysis to ascertain the extent to which their results are consistent across various missingness assumptions. Applications of different estimation methods are also illustrated using a real-data example. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  17. Healthy Families New York (HFNY) Randomized Trial: Effects on Early Child Abuse and Neglect

    ERIC Educational Resources Information Center

    DuMont, Kimberly; Mitchell-Herzfeld, Susan; Greene, Rose; Lee, Eunju; Lowenfels, Ann; Rodriguez, Monica; Dorabawila, Vajeera

    2008-01-01

    Objective: To evaluate the effects of a home visiting program modeled after Healthy Families America on parenting behaviors in the first 2 years of life. Methods: A sample of 1173 families at risk for child abuse and neglect who met the criteria for Healthy Families New York (HFNY) was randomly assigned to either an intervention group that was…

  18. Moving from Efficacy to Effectiveness in Cognitive Behavioral Therapy for Psychosis: A Randomized Clinical Practice Trial

    ERIC Educational Resources Information Center

    Lincoln, Tania M.; Ziegler, Michael; Mehl, Stephanie; Kesting, Marie-Luise; Lullmann, Eva; Westermann, Stefan; Rief, Winfried

    2012-01-01

    Objective: Randomized controlled trials have attested the efficacy of cognitive behavioral therapy (CBT) in reducing psychotic symptoms. Now, studies are needed to investigate its effectiveness in routine clinical practice settings. Method: Eighty patients with schizophrenia spectrum disorders who were seeking outpatient treatment were randomized…

  19. Effects of Assertiveness Training and Expressive Writing on Acculturative Stress in International Students: A Randomized Trial

    ERIC Educational Resources Information Center

    Tavakoli, Shedeh; Lumley, Mark A.; Hijazi, Alaa M.; Slavin-Spenny, Olga M.; Parris, George P.

    2009-01-01

    International university students often experience acculturative stress, and culturally appropriate techniques to manage stress are needed. This randomized trial tested the effects of group assertiveness training, private expressive writing, their combination, and a wait-list control on the acculturative stress, affect, and health of 118…

  20. The Effectiveness of Two Grammar Treatment Procedures for Children with SLI: A Randomized Clinical Trial

    ERIC Educational Resources Information Center

    Smith-Lock, Karen M.; Leitão, Suze; Prior, Polly; Nickels, Lyndsey

    2015-01-01

    Purpose: This study compared the effectiveness of two grammar treatment procedures for children with specific language impairment. Method: A double-blind superiority trial with cluster randomization was used to compare a cueing procedure, designed to elicit a correct production following an initial error, to a recasting procedure, which required…

  1. The Effectiveness of Two Grammar Treatment Procedures for Children with SLI: A Randomized Clinical Trial

    ERIC Educational Resources Information Center

    Smith-Lock, Karen M.; Leitão, Suze; Prior, Polly; Nickels, Lyndsey

    2015-01-01

    Purpose: This study compared the effectiveness of two grammar treatment procedures for children with specific language impairment. Method: A double-blind superiority trial with cluster randomization was used to compare a cueing procedure, designed to elicit a correct production following an initial error, to a recasting procedure, which required…

  2. Effects of Assertiveness Training and Expressive Writing on Acculturative Stress in International Students: A Randomized Trial

    ERIC Educational Resources Information Center

    Tavakoli, Shedeh; Lumley, Mark A.; Hijazi, Alaa M.; Slavin-Spenny, Olga M.; Parris, George P.

    2009-01-01

    International university students often experience acculturative stress, and culturally appropriate techniques to manage stress are needed. This randomized trial tested the effects of group assertiveness training, private expressive writing, their combination, and a wait-list control on the acculturative stress, affect, and health of 118…

  3. Effects of Aerobic Exercise on Overweight Children's Cognitive Functioning: A Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Davis, Catherine L.; Tomporowski, Phillip D.; Boyle, Colleen A.; Waller, Jennifer L.; Miller, Patricia H.; Naglieri, Jack A.; Gregoski, Mathew

    2007-01-01

    The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index [greater than or equal to] 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control…

  4. Healthy Families New York (HFNY) Randomized Trial: Effects on Early Child Abuse and Neglect

    ERIC Educational Resources Information Center

    DuMont, Kimberly; Mitchell-Herzfeld, Susan; Greene, Rose; Lee, Eunju; Lowenfels, Ann; Rodriguez, Monica; Dorabawila, Vajeera

    2008-01-01

    Objective: To evaluate the effects of a home visiting program modeled after Healthy Families America on parenting behaviors in the first 2 years of life. Methods: A sample of 1173 families at risk for child abuse and neglect who met the criteria for Healthy Families New York (HFNY) was randomly assigned to either an intervention group that was…

  5. Effects of a Voluntary Summer Reading Intervention on Reading Achievement: Results from a Randomized Field Trial

    ERIC Educational Resources Information Center

    Kim, James S.

    2006-01-01

    The effects of a voluntary summer reading intervention were assessed in a randomized field trial involving 552 students in 10 schools. In this study, fourth-grade children received eight books to read during their summer vacation and were encouraged by their teachers to practice oral reading at home with a family member and to use comprehension…

  6. The Effects of Student Coaching: An Evaluation of a Randomized Experiment in Student Advising

    ERIC Educational Resources Information Center

    Bettinger, Eric P.; Baker, Rachel B.

    2014-01-01

    College graduation rates often lag behind college attendance rates. One theory as to why students do not complete college is that they lack key information about how to be successful or fail to act on the information that they have. We present evidence from a randomized experiment which tests the effectiveness of individualized student coaching.…

  7. A Randomized Trial of Longitudinal Effects of Low-Intensity Responsivity Education/Prelinguistic Milieu Teaching

    ERIC Educational Resources Information Center

    Warren, Steven F.; Fey, Marc E.; Finestack, Lizbeth, H.; Brady, Nancy C.; Bredin-Oja, Shelley L.; Fleming, Kandace K.

    2008-01-01

    Purpose: To evaluate the longitudinal effects of a 6-month course of responsivity education (RE)/prelinguistic milieu teaching (PMT) for young children with developmental delay. Method: Fifty-one children, age 24-33 months, with fewer than 10 expressive words were randomly assigned to early-treatment/no-treatment groups. All treatment was added as…

  8. Moving from Efficacy to Effectiveness in Cognitive Behavioral Therapy for Psychosis: A Randomized Clinical Practice Trial

    ERIC Educational Resources Information Center

    Lincoln, Tania M.; Ziegler, Michael; Mehl, Stephanie; Kesting, Marie-Luise; Lullmann, Eva; Westermann, Stefan; Rief, Winfried

    2012-01-01

    Objective: Randomized controlled trials have attested the efficacy of cognitive behavioral therapy (CBT) in reducing psychotic symptoms. Now, studies are needed to investigate its effectiveness in routine clinical practice settings. Method: Eighty patients with schizophrenia spectrum disorders who were seeking outpatient treatment were randomized…

  9. A Mixture Proportional Hazards Model with Random Effects for Response Times in Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2016-01-01

    In this article, a new model for test response times is proposed that combines latent class analysis and the proportional hazards model with random effects in a similar vein as the mixture factor model. The model assumes the existence of different latent classes. In each latent class, the response times are distributed according to a…

  10. Extensions of a Versatile Randomization Test for Assessing Single-Case Intervention Effects

    ERIC Educational Resources Information Center

    Levin, Joel R.; Lall, Venessa F.; Kratochwill, Thomas R.

    2011-01-01

    The purpose of the present study was to investigate the statistical properties of two extensions of the Levin-Wampold (1999) single-case simultaneous start-point model's comparative effectiveness randomization test. The two extensions were (a) adapting the test to situations where there are more than two different intervention conditions and (b)…

  11. Random-Effects Models for Analyzing Clustered Data from a Nutrition Education Intervention.

    ERIC Educational Resources Information Center

    Woodruff, Susan I.

    1997-01-01

    Analyses of data from a nutrition education program were compared for multiple regression analysis using individual subject data, multiple regression using classroom data, two-level random effects model (REM) with subjects clustered within classrooms, and two-level REM with subjects clustered within sites. Advantages of REM are discussed. (SLD)

  12. When Repetition Isn't the Best Practice Strategy: Effects of Blocked and Random Practice Schedules

    ERIC Educational Resources Information Center

    Stambaugh, Laura A.

    2011-01-01

    The purpose of this study was to investigate the effects of blocked and random practice schedules on the performance accuracy, speed, temporal evenness, and attitude of beginning band students in a group instructional setting. The research assumptions were based on the contextual interference hypothesis, which predicts that a blocked practice…

  13. A Randomized Effectiveness Trial of Brief Cognitive-Behavioral Therapy for Depressed Adolescents Receiving Antidepressant Medication

    ERIC Educational Resources Information Center

    Clarke, Gregory; DeBar, Lynn; Lynch, Frances; Powell, James; Gale, John; O'Connor, Elizabeth; Ludman, Evette; Bush, Terry; Lin, Elizabeth H. B.; Von Korff, Michael; Hertert, Stephanie

    2005-01-01

    Objective: To test a collaborative-care, cognitive-behavioral therapy (CBT) program adjunctive to selective serotonin reuptake inhibitor (SSRI) treatment in HMO pediatric primary care. Method: A randomized effectiveness trial comparing a treatment-as-usual (TAU) control condition consisting primarily of SSRI medication delivered outside the…

  14. Effectiveness of a Parent Training Program in (Pre)Adolescence: Evidence from a Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Leijten, Patty; Overbeek, Geertjan; Janssens, Jan M. A. M.

    2012-01-01

    The present randomized controlled trial examined the effectiveness of the parent training program Parents and Children Talking Together (PCTT) for parents with children in the preadolescent period who experience parenting difficulties. The program is focused on reducing child problem behavior by improving parents' communication and problem solving…

  15. Extensions of a Versatile Randomization Test for Assessing Single-Case Intervention Effects

    ERIC Educational Resources Information Center

    Levin, Joel R.; Lall, Venessa F.; Kratochwill, Thomas R.

    2011-01-01

    The purpose of the present study was to investigate the statistical properties of two extensions of the Levin-Wampold (1999) single-case simultaneous start-point model's comparative effectiveness randomization test. The two extensions were (a) adapting the test to situations where there are more than two different intervention conditions and (b)…

  16. Cure fraction model with random effects for regional variation in cancer survival.

    PubMed

    Seppä, Karri; Hakulinen, Timo; Kim, Hyon-Jung; Läärä, Esa

    2010-11-30

    Assessing regional differences in the survival of cancer patients is important but difficult when separate regions are small or sparsely populated. In this paper, we apply a mixture cure fraction model with random effects to cause-specific survival data of female breast cancer patients collected by the population-based Finnish Cancer Registry. Two sets of random effects were used to capture the regional variation in the cure fraction and in the survival of the non-cured patients, respectively. This hierarchical model was implemented in a Bayesian framework using a Metropolis-within-Gibbs algorithm. To avoid poor mixing of the Markov chain, when the variance of either set of random effects was close to zero, posterior simulations were based on a parameter-expanded model with tailor-made proposal distributions in Metropolis steps. The random effects allowed the fitting of the cure fraction model to the sparse regional data and the estimation of the regional variation in 10-year cause-specific breast cancer survival with a parsimonious number of parameters. Before 1986, the capital of Finland clearly stood out from the rest, but since then all the 21 hospital districts have achieved approximately the same level of survival.

  17. A Mixture Proportional Hazards Model with Random Effects for Response Times in Tests

    ERIC Educational Resources Information Center

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2016-01-01

    In this article, a new model for test response times is proposed that combines latent class analysis and the proportional hazards model with random effects in a similar vein as the mixture factor model. The model assumes the existence of different latent classes. In each latent class, the response times are distributed according to a…

  18. Motivational Interviewing as a Supervision Strategy in Probation: A Randomized Effectiveness Trial

    ERIC Educational Resources Information Center

    Walters, Scott T.; Vader, Amanda M.; Nguyen, Norma; Harris, T. Robert; Eells, Jennifer

    2010-01-01

    Motivational interviewing (MI) has been recommended as a supervision style in probation. This project examined the effectiveness of an MI training curriculum on probation officer MI skill and subsequent probationer outcome. Twenty probation officers were randomized to receive MI training, or to a waiting list control, while an additional group of…

  19. Motivational Interviewing as a Supervision Strategy in Probation: A Randomized Effectiveness Trial

    ERIC Educational Resources Information Center

    Walters, Scott T.; Vader, Amanda M.; Nguyen, Norma; Harris, T. Robert; Eells, Jennifer

    2010-01-01

    Motivational interviewing (MI) has been recommended as a supervision style in probation. This project examined the effectiveness of an MI training curriculum on probation officer MI skill and subsequent probationer outcome. Twenty probation officers were randomized to receive MI training, or to a waiting list control, while an additional group of…

  20. The Instructional Effectiveness of Random, Logical and Ordering Theory Generated Learning Hierarchies.

    ERIC Educational Resources Information Center

    Partin, Ronald L.

    The instructional effectiveness of learning programs derived from Gagne-type task analysis, ordering theory analysis, and random sequenced presentation of complex intellectual skills were investigated. Fifty-seven high school students completed a self-instructional program derived from one of the three sequences. No significant differences were…

  1. Randomized controlled trial to assess the effectiveness of a videotape about radiotherapy

    PubMed Central

    Harrison, R; Dey, P; Slevin, N J; Eardley, A; Gibbs, A; Cowan, R; Logue, J P; Leidecker, V; Hopwood, P

    2001-01-01

    In a randomized controlled trial, the additional provision of information on videotape was no more effective than written information alone in reducing pre-treatment worry about radiotherapy. Images of surviving cancer patients, however, may provide further reassurance to patients once therapy is completed. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11139305

  2. Testing Mediators of Intervention Effects in Randomized Controlled Trials: An Evaluation of Three Depression Prevention Programs

    ERIC Educational Resources Information Center

    Stice, Eric; Rohde, Paul; Seeley, John R.; Gau, Jeff M.

    2010-01-01

    Objective: Evaluate a new 5-step method for testing mediators hypothesized to account for the effects of depression prevention programs. Method: In this indicated prevention trial, at-risk teens with elevated depressive symptoms were randomized to a group cognitive-behavioral (CB) intervention, group supportive expressive intervention, CB…

  3. The Effects of Student Coaching: An Evaluation of a Randomized Experiment in Student Advising

    ERIC Educational Resources Information Center

    Bettinger, Eric P.; Baker, Rachel B.

    2014-01-01

    College graduation rates often lag behind college attendance rates. One theory as to why students do not complete college is that they lack key information about how to be successful or fail to act on the information that they have. We present evidence from a randomized experiment which tests the effectiveness of individualized student coaching.…

  4. High-Dimensional Explanatory Random Item Effects Models for Rater-Mediated Assessments

    ERIC Educational Resources Information Center

    Kelcey, Ben; Wang, Shanshan; Cox, Kyle

    2016-01-01

    Valid and reliable measurement of unobserved latent variables is essential to understanding and improving education. A common and persistent approach to assessing latent constructs in education is the use of rater inferential judgment. The purpose of this study is to develop high-dimensional explanatory random item effects models designed for…

  5. Effectiveness of Stepped Care for Chronic Fatigue Syndrome: A Randomized Noninferiority Trial

    ERIC Educational Resources Information Center

    Tummers, Marcia; Knoop, Hans; Bleijenberg, Gijs

    2010-01-01

    Objective: In this randomized noninferiority study, the effectiveness and efficiency of stepped care for chronic fatigue syndrome (CFS) was compared to care as usual. Stepped care was formed by guided self-instruction, followed by cognitive behavior therapy (CBT) if the patient desired it. Care as usual encompassed CBT after a waiting period.…

  6. Exploring Mechanisms of Effective Teacher Coaching: A Tale of Two Cohorts From a Randomized Experiment

    ERIC Educational Resources Information Center

    Blazar, David; Kraft, Matthew A.

    2015-01-01

    Although previous research has shown that teacher coaching can improve teaching practices and student achievement, little is known about specific features of effective coaching programs. We estimate the impact of MATCH Teacher Coaching (MTC) on a range of teacher practices using a blocked randomized trial and explore how changes in the coaching…

  7. Exploring Mechanisms of Effective Teacher Coaching: A Tale of Two Cohorts From a Randomized Experiment

    ERIC Educational Resources Information Center

    Blazar, David; Kraft, Matthew A.

    2015-01-01

    Although previous research has shown that teacher coaching can improve teaching practices and student achievement, little is known about specific features of effective coaching programs. We estimate the impact of MATCH Teacher Coaching (MTC) on a range of teacher practices using a blocked randomized trial and explore how changes in the coaching…

  8. The Implications of Teacher Selection and Teacher Effects in Individually Randomized Group Treatment Trials

    ERIC Educational Resources Information Center

    Weiss, Michael J.

    2010-01-01

    Randomized experiments have become an increasingly popular design to evaluate the effectiveness of interventions in education (Spybrook, 2008). Many of the interventions evaluated in education are delivered to groups of students, rather than to individuals. Experiments designed to evaluate programs delivered at the group level often…

  9. Revisiting Fixed- and Random-Effects Models: Some Considerations for Policy-Relevant Education Research

    ERIC Educational Resources Information Center

    Clarke, Paul; Crawford, Claire; Steele, Fiona; Vignoles, Anna

    2015-01-01

    The use of fixed (FE) and random effects (RE) in two-level hierarchical linear regression is discussed in the context of education research. We compare the robustness of FE models with the modelling flexibility and potential efficiency of those from RE models. We argue that the two should be seen as complementary approaches. We then compare both…

  10. Effects of Behavioral Marital Therapy: A Meta-Analysis of Randomized Controlled Trials

    ERIC Educational Resources Information Center

    Shadish, William R.; Baldwin, Scott A.

    2005-01-01

    This meta-analysis summarizes results from 30 randomized experiments that compare behavioral marital therapy with no-treatment control with distressed couples. Results showed that behavioral marital therapy is significantly more effective than no treatment (d=.585). Although behavioral marital therapy research studies tend to be conducted under…

  11. The Effectiveness of Healthy Start Home Visit Program: Cluster Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Leung, Cynthia; Tsang, Sandra; Heung, Kitty

    2015-01-01

    Purpose: The study reported the effectiveness of a home visit program for disadvantaged Chinese parents with preschool children, using cluster randomized controlled trial design. Method: Participants included 191 parents and their children from 24 preschools, with 84 dyads (12 preschools) in the intervention group and 107 dyads (12 preschools) in…

  12. Effects of Aerobic Exercise on Overweight Children's Cognitive Functioning: A Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Davis, Catherine L.; Tomporowski, Phillip D.; Boyle, Colleen A.; Waller, Jennifer L.; Miller, Patricia H.; Naglieri, Jack A.; Gregoski, Mathew

    2007-01-01

    The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index [greater than or equal to] 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control…

  13. A General Panel Model with Random and Fixed Effects: A Structural Equations Approach

    ERIC Educational Resources Information Center

    Bollen, Kenneth A.; Brand, Jennie E.

    2010-01-01

    Fixed- and random-effects models for longitudinal data are common in sociology. Their primary advantage is that they control for time-invariant omitted variables. However, analysts face several issues when they employ these models. One is the choice of which to apply; another is that FEM and REM models as usually implemented might be…

  14. An Evaluation of Information Criteria Use for Correct Cross-Classified Random Effects Model Selection

    ERIC Educational Resources Information Center

    Beretvas, S. Natasha; Murphy, Daniel L.

    2013-01-01

    The authors assessed correct model identification rates of Akaike's information criterion (AIC), corrected criterion (AICC), consistent AIC (CAIC), Hannon and Quinn's information criterion (HQIC), and Bayesian information criterion (BIC) for selecting among cross-classified random effects models. Performance of default values for the 5…

  15. A Randomized Effectiveness Trial of Brief Cognitive-Behavioral Therapy for Depressed Adolescents Receiving Antidepressant Medication

    ERIC Educational Resources Information Center

    Clarke, Gregory; DeBar, Lynn; Lynch, Frances; Powell, James; Gale, John; O'Connor, Elizabeth; Ludman, Evette; Bush, Terry; Lin, Elizabeth H. B.; Von Korff, Michael; Hertert, Stephanie

    2005-01-01

    Objective: To test a collaborative-care, cognitive-behavioral therapy (CBT) program adjunctive to selective serotonin reuptake inhibitor (SSRI) treatment in HMO pediatric primary care. Method: A randomized effectiveness trial comparing a treatment-as-usual (TAU) control condition consisting primarily of SSRI medication delivered outside the…

  16. Educational Effects of the Tools of the Mind Curriculum: A Randomized Trial

    ERIC Educational Resources Information Center

    Barnett, W.Steven; Jung, Kwanghee; Yarosz, Donald J.; Thomas, Jessica; Hornbeck, Amy; Stechuk, Robert; Burns, Susan

    2008-01-01

    The effectiveness of the "Tools of the Mind (Tools)" curriculum in improving the education of 3- and 4-year-old children was evaluated by means of a randomized trial. The "Tools" curriculum, based on the work of Vygotsky, focuses on the development of self-regulation at the same time as teaching literacy and mathematics skills…

  17. Revisiting Fixed- and Random-Effects Models: Some Considerations for Policy-Relevant Education Research

    ERIC Educational Resources Information Center

    Clarke, Paul; Crawford, Claire; Steele, Fiona; Vignoles, Anna

    2015-01-01

    The use of fixed (FE) and random effects (RE) in two-level hierarchical linear regression is discussed in the context of education research. We compare the robustness of FE models with the modelling flexibility and potential efficiency of those from RE models. We argue that the two should be seen as complementary approaches. We then compare both…

  18. The Effectiveness of Healthy Start Home Visit Program: Cluster Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Leung, Cynthia; Tsang, Sandra; Heung, Kitty

    2015-01-01

    Purpose: The study reported the effectiveness of a home visit program for disadvantaged Chinese parents with preschool children, using cluster randomized controlled trial design. Method: Participants included 191 parents and their children from 24 preschools, with 84 dyads (12 preschools) in the intervention group and 107 dyads (12 preschools) in…

  19. Effectiveness of a Parent Training Program in (Pre)Adolescence: Evidence from a Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Leijten, Patty; Overbeek, Geertjan; Janssens, Jan M. A. M.

    2012-01-01

    The present randomized controlled trial examined the effectiveness of the parent training program Parents and Children Talking Together (PCTT) for parents with children in the preadolescent period who experience parenting difficulties. The program is focused on reducing child problem behavior by improving parents' communication and problem solving…

  20. Effectiveness of Stepped Care for Chronic Fatigue Syndrome: A Randomized Noninferiority Trial

    ERIC Educational Resources Information Center

    Tummers, Marcia; Knoop, Hans; Bleijenberg, Gijs

    2010-01-01

    Objective: In this randomized noninferiority study, the effectiveness and efficiency of stepped care for chronic fatigue syndrome (CFS) was compared to care as usual. Stepped care was formed by guided self-instruction, followed by cognitive behavior therapy (CBT) if the patient desired it. Care as usual encompassed CBT after a waiting period.…

  1. An Evaluation of Information Criteria Use for Correct Cross-Classified Random Effects Model Selection

    ERIC Educational Resources Information Center

    Beretvas, S. Natasha; Murphy, Daniel L.

    2013-01-01

    The authors assessed correct model identification rates of Akaike's information criterion (AIC), corrected criterion (AICC), consistent AIC (CAIC), Hannon and Quinn's information criterion (HQIC), and Bayesian information criterion (BIC) for selecting among cross-classified random effects models. Performance of default values for the 5…

  2. Effects of excluding a set of random effects on prediction error variance of breeding value.

    PubMed

    Cantet, R J

    1997-01-12

    The effects of excluding a set of random effects (U-effects) uncorrelated to breeding values (BV) on prediction error variance (PEV) is studied analytically. Two situations are considered for model comparison: (a) existence of a 'true' model, (b) uncertainty about which of the competing models is 'true'. Models compared are the 'long' one, which includes BV + U-effects, and the 'short' one which includes BV's as the only random systematic effect. Expressions for PEV(BV) were obtained for the long model (PEVL); the short model (PEVS); and the short model assuming the long model is the correct one (PEVSI). It is shown that in general PEVS ≤ PEVL ≤ PEVSI. Results are exemplified by means of an example including a computer simulation. RESUMEN: En este trabajo se estudia analiticamente el efecto de excluir una variable aleatoria (efecto U) no correlacionada con el valor de cría (BV), sobre la varianza del error de predicción de este último (PEV(BV)). Para ello se utilizan dos enfoques de comparación de modelos: (a) existencia de un modelo 'verdadero', (b) incertidumbre respecto de cuál de ambos modelos alternativos es el correcto. Los modelos que se comparan son: el 'largo', que incluye BV+U, y el 'corto', el cuál solo incluye BV. Se obtienen las expresiones para PEV(BV) en las siguientes situaciones: (1) en el modelo largo (PEVL), (2) en el modelo corto (PEVS), y (3) en el modelo corto pero asumiendo que el largo es el verdadero (PEVSI). Se demuestra que en general PEVS ≤ PEVL ≤ PEVSI. Los resultados obtenidos son ilustrados mediante un ejemplo que incluye una simulación estocástica. ZUSAMMENFASSUNG: Veränderung der Fehlervarianz der Zuchtwertvoraussage durch Vernachlässigung einer Gruppe zufäliger Wirkungen. Es wird die Auswirkung der Ausschaltung einer Gruppe zufälliger Wirkungen (U-effects), die mit Zuchtwerten (BV) nicht korreliert sind, auf die Varianz des Voraussage-Fehlers (PEV) analytisch untersucht. Zwei Modelle werden betrachtet: (a

  3. A randomized comparison of three chest compression techniques and associated hemodynamic effect during infant CPR: A randomized manikin study.

    PubMed

    Smereka, Jacek; Szarpak, Lukasz; Rodríguez-Núñez, Antonio; Ladny, Jerzy R; Leung, Steve; Ruetzler, Kurt

    2017-10-01

    Pediatric cardiac arrest is an uncommon but critical life-threatening event requiring effective cardiopulmonary resuscitation. High-quality cardio-pulmonary resuscitation (CPR) is essential, but is poorly performed, even by highly skilled healthcare providers. The recently described two-thumb chest compression technique (nTTT) consists of the two thumbs directed at the angle of 90° to the chest while having the fingers fist-clenched. This technique might facilitate adequate chest-compression depth, chest-compression rate and rate of full chest-pressure relief. 42 paramedics from the national Emergency Medical Service of Poland performed three single-rescuer CPR sessions for 10 minutes each. Each session was randomly assigned to the conventional two-thumb (TTHT), the conventional two-finger (TFT) or the nTTT. The manikin used for this study was connected with an arterial blood pressure measurement device and blood measurements were documented on a 10-seconds cycle. The nTTT provided significant higher systolic (82 vs. 30 vs. 41 mmHg). A statistically significant difference was noticed between nTTT and TFT (p<.001), nTTT and TTHT (p<0.001), TFT and TTHT (p=0.003). The median diastolic preassure using nTTT was 16 mmHg compared with 9 mmHg for TFT (p<0.001), and 9.5 mmHg for TTHT (p<0.001). Mean arterial pressure using distinct methods varied and amounted to 40 vs. 22. vs. 26 mmHg (nTTT vs. TFT vs. TTHT, respectively). A statistically significant difference was noticed between nTTT and TFT (p<0.001), nTTT and TTEHT (p<0.001), and TFT and TTHT (p<0.001). The highest median pulse pressure was obtained by the nTTT 67.5 mmHg. Pulse pressure was 31.5 mmHg in the TTHT and 24 mmHg in the TFT. The difference between TFT and TTHT (p=0.025), TFT and nTTT (p<0.001), as well as between TTHT and nTTT (p<0.001) were statistically significant. The new nTTT technique generated higher arterial blood pressures compared to established chest compression techniques using an infant manikin

  4. A random effects variance shift model for detecting and accommodating outliers in meta-analysis

    PubMed Central

    2011-01-01

    Background Meta-analysis typically involves combining the estimates from independent studies in order to estimate a parameter of interest across a population of studies. However, outliers often occur even under the random effects model. The presence of such outliers could substantially alter the conclusions in a meta-analysis. This paper proposes a methodology for identifying and, if desired, downweighting studies that do not appear representative of the population they are thought to represent under the random effects model. Methods An outlier is taken as an observation (study result) with an inflated random effect variance. We used the likelihood ratio test statistic as an objective measure for determining whether observations have inflated variance and are therefore considered outliers. A parametric bootstrap procedure was used to obtain the sampling distribution of the likelihood ratio test statistics and to account for multiple testing. Our methods were applied to three illustrative and contrasting meta-analytic data sets. Results For the three meta-analytic data sets our methods gave robust inferences when the identified outliers were downweighted. Conclusions The proposed methodology provides a means to identify and, if desired, downweight outliers in meta-analysis. It does not eliminate them from the analysis however and we consider the proposed approach preferable to simply removing any or all apparently outlying results. We do not however propose that our methods in any way replace or diminish the standard random effects methodology that has proved so useful, rather they are helpful when used in conjunction with the random effects model. PMID:21324180

  5. Pragmatic randomized trial evaluating the clinical and economic effectiveness of acupuncture for chronic low back pain.

    PubMed

    Witt, Claudia M; Jena, Susanne; Selim, Dagmar; Brinkhaus, Benno; Reinhold, Thomas; Wruck, Katja; Liecker, Bodo; Linde, Klaus; Wegscheider, Karl; Willich, Stefan N

    2006-09-01

    In a randomized controlled trial plus a nonrandomized cohort, the authors investigated the effectiveness and costs of acupuncture in addition to routine care in the treatment of chronic low back pain and assessed whether the effects of acupuncture differed in randomized and nonrandomized patients. In 2001, German patients with chronic low back pain were allocated to an acupuncture group or a no-acupuncture control group. Persons who did not consent to randomization were included in a nonrandomized acupuncture group. All patients were allowed to receive routine medical care in addition to study treatment. Back function (Hannover Functional Ability Questionnaire), pain, and quality of life were assessed at baseline and after 3 and 6 months, and cost-effectiveness was analyzed. Of 11,630 patients (mean age=52.9 years (standard deviation, 13.7); 59% female), 1,549 were randomized to the acupuncture group and 1,544 to the control group; 8,537 were included in the nonrandomized acupuncture group. At 3 months, back function improved by 12.1 (standard error (SE), 0.4) to 74.5 (SE, 0.4) points in the acupuncture group and by 2.7 (SE, 0.4) to 65.1 (SE, 0.4) points among controls (difference=9.4 points (95% confidence interval 8.3, 10.5); p<0.001). Nonrandomized patients had more severe symptoms at baseline and showed improvements in back function similar to those seen in randomized patients. The incremental cost-effectiveness ratio was euro10,526 (euros) per quality-adjusted life year. Acupuncture plus routine care was associated with marked clinical improvements in these patients and was relatively cost-effective.

  6. Full Bayes Poisson gamma, Poisson lognormal, and zero inflated random effects models: Comparing the precision of crash frequency estimates.

    PubMed

    Aguero-Valverde, Jonathan

    2013-01-01

    In recent years, complex statistical modeling approaches have being proposed to handle the unobserved heterogeneity and the excess of zeros frequently found in crash data, including random effects and zero inflated models. This research compares random effects, zero inflated, and zero inflated random effects models using a full Bayes hierarchical approach. The models are compared not just in terms of goodness-of-fit measures but also in terms of precision of posterior crash frequency estimates since the precision of these estimates is vital for ranking of sites for engineering improvement. Fixed-over-time random effects models are also compared to independent-over-time random effects models. For the crash dataset being analyzed, it was found that once the random effects are included in the zero inflated models, the probability of being in the zero state is drastically reduced, and the zero inflated models degenerate to their non zero inflated counterparts. Also by fixing the random effects over time the fit of the models and the precision of the crash frequency estimates are significantly increased. It was found that the rankings of the fixed-over-time random effects models are very consistent among them. In addition, the results show that by fixing the random effects over time, the standard errors of the crash frequency estimates are significantly reduced for the majority of the segments on the top of the ranking. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Peer Effects in the Workplace: Evidence from Random Groupings in Professional Golf Tournaments

    PubMed Central

    Guryan, Jonathan; Kroft, Kory; Notowidigdo, Matthew J.

    2010-01-01

    This paper uses random assignment in professional golf tournaments to test for peer effects in the workplace. We find no evidence that playing partners’ ability affects performance, contrary to recent evidence on peer effects in the workplace from laboratory experiments, grocery scanners, and soft-fruit pickers. In our preferred specification we can rule out peer effects larger than 0.043 strokes for a one stroke increase in playing partners’ ability. Our results complement existing studies on workplace peer effects and are useful in explaining how social effects vary across labor markets, across individuals, and with the form of incentives faced. PMID:20454555

  8. Fixed-, Random-, and Mixed-Effects ANOVA Models: A User-Friendly Guide for Increasing the Generalizability of ANOVA Results.

    ERIC Educational Resources Information Center

    Frederick, Brigitte N.

    Most researchers using analysis of variance (ANOVA) use a fixed-effects model. However, a random- or mixed-effects model may be a more appropriate fit for many research designs. One benefit of the random- and mixed-effects models is that they yield more generalizable results. This paper focuses on the similarities and differences between the…

  9. Effectiveness of energy conservation management on fatigue and participation in multiple sclerosis: A randomized controlled trial.

    PubMed

    Blikman, Lyan Jm; van Meeteren, Jetty; Twisk, Jos Wr; de Laat, Fred Aj; de Groot, Vincent; Beckerman, Heleen; Stam, Henk J; Bussmann, Johannes Bj

    2017-10-01

    Fatigue is a frequently reported and disabling symptom in multiple sclerosis (MS). To investigate the effectiveness of an individual energy conservation management (ECM) intervention on fatigue and participation in persons with primary MS-related fatigue. A total of 86 severely fatigued and ambulatory adults with a definite diagnosis of MS were randomized in a single-blind, two-parallel-arm randomized clinical trial to the ECM group or the information-only control group in outpatient rehabilitation departments. Blinded assessments were carried out at baseline and at 8, 16, 26 and 52 weeks after randomization. Primary outcomes were fatigue (fatigue subscale of Checklist Individual Strength - CIS20r) and participation (Impact on Participation and Autonomy scale - IPA). Modified intention-to-treat analysis was based on 76 randomized patients (ECM, n = 36; MS nurse, n=40). No significant ECM effects were found for fatigue (overall difference CIS20r between the groups = -0.81; 95% confidence interval (CI), -3.71 to 2.11) or for four out of five IPA domains. An overall unfavourable effect was found in the ECM group for the IPA domain social relations (difference between the groups = 0.19; 95% CI, 0.03 to 0.35). The individual ECM format used in this study did not reduce MS-related fatigue and restrictions in participation more than an information-only control condition.

  10. Estimation of treatment efficacy with complier average causal effects (CACE) in a randomized stepped wedge trial.

    PubMed

    Gruber, Joshua S; Arnold, Benjamin F; Reygadas, Fermin; Hubbard, Alan E; Colford, John M

    2014-05-01

    Complier average causal effects (CACE) estimate the impact of an intervention among treatment compliers in randomized trials. Methods used to estimate CACE have been outlined for parallel-arm trials (e.g., using an instrumental variables (IV) estimator) but not for other randomized study designs. Here, we propose a method for estimating CACE in randomized stepped wedge trials, where experimental units cross over from control conditions to intervention conditions in a randomized sequence. We illustrate the approach with a cluster-randomized drinking water trial conducted in rural Mexico from 2009 to 2011. Additionally, we evaluated the plausibility of assumptions required to estimate CACE using the IV approach, which are testable in stepped wedge trials but not in parallel-arm trials. We observed small increases in the magnitude of CACE risk differences compared with intention-to-treat estimates for drinking water contamination (risk difference (RD) = -22% (95% confidence interval (CI): -33, -11) vs. RD = -19% (95% CI: -26, -12)) and diarrhea (RD = -0.8% (95% CI: -2.1, 0.4) vs. RD = -0.1% (95% CI: -1.1, 0.9)). Assumptions required for IV analysis were probably violated. Stepped wedge trials allow investigators to estimate CACE with an approach that avoids the stronger assumptions required for CACE estimation in parallel-arm trials. Inclusion of CACE estimates in stepped wedge trials with imperfect compliance could enhance reporting and interpretation of the results of such trials.

  11. Effective method for emergency fertility preservation: random-start controlled ovarian stimulation.

    PubMed

    Cakmak, Hakan; Katz, Audra; Cedars, Marcelle I; Rosen, Mitchell P

    2013-12-01

    To determine whether random-start controlled ovarian stimulation (COS), in which a patient is stimulated on presentation regardless of her menstrual-cycle phase, has outcomes similar to conventional early follicular phase-start COS for fertility preservation in cancer patients. Retrospective cohort study. Academic medical center. Women recently diagnosed with cancer and in preparation for gonadotoxic therapy. Random- versus conventional-start COS. number of mature oocytes retrieved; secondary outcomes: pattern of follicular development, oocyte yield, and fertilization rate. The number of total and mature oocytes retrieved, oocyte maturity rate, mature oocyte yield, and fertilization rates were similar in random- (n = 35) and conventional-start (n = 93) COS cycles. No superiority was noted when comparing COS started in the late follicular (n = 13) or luteal phase (n = 22). The addition of letrozole, in the case of estrogen-sensitive cancers, did not adversely affect COS outcomes or oocyte maturity and competence in either random- or conventional-start protocols. Random-start COS is as effective as conventional-start COS in fertility preservation. This protocol would minimize delays and allow more patients to undergo fertility preservation and still proceed with cancer treatment within 2-3 weeks. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  12. Effectiveness of the clinical teaching associate model to improve clinical learning outcomes: a randomized controlled trial.

    PubMed

    Parchebafieh, Samaneh; Gholizadeh, Leila; Lakdizaji, Sima; Ghiasvandiyan, Shahrzad; Davoodi, Arefeh

    2014-01-01

    This study examined the effectiveness of the clinical teaching associate (CTA) model to improve clinical learning outcomes in nursing students. Students were randomly allocated to either the CTA (n = 28) or traditional training group (n = 32), and their clinical knowledge, skills, and satisfaction with the learning experience were assessed and compared. The results showed that the CTA model was equally effective in improving clinical knowledge, skills, and satisfaction of nursing students.

  13. The Effects of Random Vibration on the Dimensional Stability of Precision Structures

    NASA Astrophysics Data System (ADS)

    Edeson, Ruben L.; Aglietti, Guglielmo S.; Tatnall, Adrian R.

    2012-07-01

    Precision structures for space-based optical systems are typically subjected to brief periods of random vibration during the launch and ground testing phases. Such events pose a potential threat to the dimensional stability of such structures, which may be required to maintain positional tolerances on large optics in the low 10s of microns to meet optical performance requirements. Whilst there is an abundance of information in the literature on structural instability caused by hygrothermal cycling, there appears to have been little work done on the effects of random vibration. This issue has recently been addressed at RAL with a series of tests aimed at characterizing the behavior of dimensional instability in structures for high-resolution Earth-imaging cameras subject to random vibration. Firstly, a breadboard model of a typical “conventional” CFRP-based optical payload structure was produced and subjected to a range of environmental tests. The effects of random vibration were compared to those of other environmental stressors (such as thermal vacuum testing) and found to be significant. Next, controlled tests were performed on specific structural areas in order to assess the specific contributions of each area to overall instability. These tests made use of novel test setups and metrology techniques to assess the dimensional stability response of material samples and bolted joints to random vibration exposure. The tests were able to measure dimensional instability, characterize it over a series of tests of increasing vibration levels, and assess variability in results between identical samples. Finally, a predictive technique using a Finite Element Model with nonlinear kinematic hardening was produced. A time domain solution was obtained, using an analogy to Miner’s Rule to determine load cycle amplitudes. This model correlated reasonably well with test results. This paper presents this program of work, and the results. It also proposes ways to minimize

  14. Minimizing nocebo effects by conditioning with verbal suggestion: A randomized clinical trial in healthy humans.

    PubMed

    Bartels, Danielle J P; van Laarhoven, Antoinette I M; Stroo, Michiel; Hijne, Kim; Peerdeman, Kaya J; Donders, A Rogier T; van de Kerkhof, Peter C M; Evers, Andrea W M

    2017-01-01

    Nocebo effects, i.e., adverse treatment effects which are induced by patients' expectations, are known to contribute to the experience of physical symptoms such as pain and itch. A better understanding of how to minimize nocebo responses might eventually contribute to enhanced treatment effects. However, little is known about how to reduce nocebo effects. In the current randomized controlled study, we tested whether nocebo effects can be minimized by positive expectation induction with respect to electrical and histaminic itch stimuli. First, negative expectations about electrical itch stimuli were induced by verbal suggestion and conditioning (part 1: induction of nocebo effect). Second, participants were randomized to either the experimental group or one of the control groups (part 2: reversing nocebo effect). In the experimental group, positive expectations were induced by conditioning with verbal suggestion. In the control groups either the negative expectation induction was continued or an extinction procedure was applied. Afterwards, a histamine application test was conducted. Positive expectation induction resulted in a significantly smaller nocebo effect in comparison with both control groups. Mean change itch NRS scores showed that the nocebo effect was even reversed, indicating a placebo effect. Comparable effects were also found for histamine application. This study is the first to demonstrate that nocebo effects can be minimized and even reversed by conditioning with verbal suggestion. The results of the current study indicate that learning via counterconditioning and verbal suggestion represents a promising strategy for diminishing nocebo responses.

  15. Bayesian Estimation and Testing in Random Effects Meta-analysis of Rare Binary Adverse Events.

    PubMed

    Bai, Ou; Chen, Min; Wang, Xinlei

    Meta-analysis has been widely applied to rare adverse event data because it is very difficult to reliably detect the effect of a treatment on such events in an individual clinical study. However, it is known that standard meta-analysis methods are often biased, especially when the background incidence rate is very low. A recent work by Bhaumik et al. (2012) proposed new moment-based approaches under a natural random effects model, to improve estimation and testing of the treatment effect and the between-study heterogeneity parameter. It has been demonstrated that for rare binary events, their methods have superior performance to commonly-used meta-analysis methods. However, their comparison does not include any Bayesian methods, although Bayesian approaches are a natural and attractive choice under the random-effects model. In this paper, we study a Bayesian hierarchical approach to estimation and testing in meta-analysis of rare binary events using the random effects model in Bhaumik et al. (2012). We develop Bayesian estimators of the treatment effect and the heterogeneity parameter, as well as hypothesis testing methods based on Bayesian model selection procedures. We compare them with the existing methods through simulation. A data example is provided to illustrate the Bayesian approach as well.

  16. The Expected Sample Variance of Uncorrelated Random Variables with a Common Mean and Some Applications in Unbalanced Random Effects Models

    ERIC Educational Resources Information Center

    Vardeman, Stephen B.; Wendelberger, Joanne R.

    2005-01-01

    There is a little-known but very simple generalization of the standard result that for uncorrelated random variables with common mean [mu] and variance [sigma][superscript 2], the expected value of the sample variance is [sigma][superscript 2]. The generalization justifies the use of the usual standard error of the sample mean in possibly…

  17. Defining a Clinically Meaningful Effect for the Design and Interpretation of Randomized Controlled Trials

    PubMed Central

    Kraemer, Helena C.; Epstein, Robert S.; Frank, Ellen; Haynes, Ginger; Laughren, Thomas P.; Mcnulty, James; Reed, Shelby D.; Sanchez, Juan; Leon, Andrew C.

    2013-01-01

    Objective: This article captures the proceedings of a meeting aimed at defining clinically meaningful effects for use in randomized controlled trials for psychopharmacological agents. Design: Experts from a variety of disciplines defined clinically meaningful effects from their perspectives along with viewpoints about how to design and interpret randomized controlled trials. Setting: The article offers relevant, practical, and sometimes anecdotal information about clinically meaningful effects and how to interpret them. Participants: The concept for this session was the work of co-chairs Richard Keefe and the late Andy Leon. Faculty included Richard Keefe, PhD; James McNulty, AbScB; Robert S. Epstein, MD, MS; Shelby D. Reed, PhD; Juan Sanchez, MD; Ginger Haynes, PhD; Andrew C. Leon, PhD; Helena Chmura Kraemer, PhD; Ellen Frank, PhD, and Kenneth L. Davis, MD. Results: The term clinically meaningful effect is an important aspect of designing and interpreting randomized controlled trials but can be particularly difficult in the setting of psychopharmacology where effect size may be modest, particularly over the short term, because of a strong response to placebo. Payers, regulators, patients, and clinicians have different concerns about clinically meaningful effects and may describe these terms differently. The use of moderators in success rate differences may help better delineate clinically meaningful effects. Conclusion: There is no clear consensus on a single definition for clinically meaningful differences in randomized controlled trials, and investigators must be sensitive to specific concerns of stakeholders in psychopharmacology in order to design and execute appropriate clinical trials. PMID:23882433

  18. Self-Powered Random Number Generator Based on Coupled Triboelectric and Electrostatic Induction Effects at the Liquid-Dielectric Interface.

    PubMed

    Yu, Aifang; Chen, Xiangyu; Cui, Haotian; Chen, Libo; Luo, Jianjun; Tang, Wei; Peng, Mingzeng; Zhang, Yang; Zhai, Junyi; Wang, Zhong Lin

    2016-12-27

    Modern cryptography increasingly employs random numbers generated from physical sources in lieu of conventional software-based pseudorandom numbers, primarily owing to the great demand of unpredictable, indecipherable cryptographic keys from true random numbers for information security. Thus, far, the sole demonstration of true random numbers has been generated through thermal noise and/or quantum effects, which suffers from expensive and complex equipment. In this paper, we demonstrate a method for self-powered creation of true random numbers by using triboelectric technology to collect random signals from nature. This random number generator based on coupled triboelectric and electrostatic induction effects at the liquid-dielectric interface includes an elaborately designed triboelectric generator (TENG) with an irregular grating structure, an electronic-optical device, and an optical-electronic device. The random characteristics of raindrops are harvested through TENG and consequently transformed and converted by electronic-optical device and an optical-electronic device with a nonlinear characteristic. The cooperation of the mechanical, electrical, and optical signals ensures that the generator possesses complex nonlinear input-output behavior and contributes to increased randomness. The random number sequences are deduced from final electrical signals received by an optical-electronic device using a familiar algorithm. These obtained random number sequences exhibit good statistical characteristics, unpredictability, and unrepeatability. Our study supplies a simple, practical, and effective method to generate true random numbers, which can be widely used in cryptographic protocols, digital signatures, authentication, identification, and other information security fields.

  19. An Evaluation of the Effectiveness of Recruitment Methods: The Staying Well after Depression Randomized Controlled Trial

    PubMed Central

    Krusche, Adele; Rudolf von Rohr, Isabelle; Muse, Kate; Duggan, Danielle; Crane, Catherine; Williams, J. Mark G.

    2014-01-01

    Background Randomized controlled trials (RCTs) are widely accepted as being the most efficient way of investigating the efficacy of psychological therapies. However, researchers conducting RCTs commonly report difficulties recruiting an adequate sample within planned timescales. In an effort to overcome recruitment difficulties, researchers often are forced to expand their recruitment criteria or extend the recruitment phase, thus increasing costs and delaying publication of results. Research investigating the effectiveness of recruitment strategies is limited and trials often fail to report sufficient details about the recruitment sources and resources utilised. Purpose We examined the efficacy of strategies implemented during the Staying Well after Depression RCT in Oxford to recruit participants with a history of recurrent depression. Methods We describe eight recruitment methods utilised and two further sources not initiated by the research team and examine their efficacy in terms of (i) the return, including the number of potential participants who contacted the trial and the number who were randomized into the trial, (ii) cost-effectiveness, comprising direct financial cost and manpower for initial contacts and randomized participants, and (iii) comparison of sociodemographic characteristics of individuals recruited from different sources. Results Poster advertising, web-based advertising and mental health worker referrals were the cheapest methods per randomized participant; however, the ratio of randomized participants to initial contacts differed markedly per source. Advertising online, via posters and on a local radio station were the most cost-effective recruitment methods for soliciting participants who subsequently were randomized into the trial. Advertising across many sources (saturation) was found to be important. Limitations It may not be feasible to employ all the recruitment methods used in this trial to obtain participation from other

  20. An evaluation of the effectiveness of recruitment methods: the staying well after depression randomized controlled trial.

    PubMed

    Krusche, Adele; Rudolf von Rohr, Isabelle; Muse, Kate; Duggan, Danielle; Crane, Catherine; Williams, J Mark G

    2014-04-01

    Randomized controlled trials (RCTs) are widely accepted as being the most efficient way of investigating the efficacy of psychological therapies. However, researchers conducting RCTs commonly report difficulties in recruiting an adequate sample within planned timescales. In an effort to overcome recruitment difficulties, researchers often are forced to expand their recruitment criteria or extend the recruitment phase, thus increasing costs and delaying publication of results. Research investigating the effectiveness of recruitment strategies is limited, and trials often fail to report sufficient details about the recruitment sources and resources utilized. We examined the efficacy of strategies implemented during the Staying Well after Depression RCT in Oxford to recruit participants with a history of recurrent depression. We describe eight recruitment methods utilized and two further sources not initiated by the research team and examine their efficacy in terms of (1) the return, including the number of potential participants who contacted the trial and the number who were randomized into the trial; (2) cost-effectiveness, comprising direct financial cost and manpower for initial contacts and randomized participants; and (3) comparison of sociodemographic characteristics of individuals recruited from different sources. Poster advertising, web-based advertising, and mental health worker referrals were the cheapest methods per randomized participant; however, the ratio of randomized participants to initial contacts differed markedly per source. Advertising online, via posters, and on a local radio station were the most cost-effective recruitment methods for soliciting participants who subsequently were randomized into the trial. Advertising across many sources (saturation) was found to be important. It may not be feasible to employ all the recruitment methods used in this trial to obtain participation from other populations, such as those currently unwell, or in

  1. Seismic spatial effects on long-span bridge response in nonstationary inhomogeneous random fields

    NASA Astrophysics Data System (ADS)

    Jiahao, Lin; Yahui, Zhang; Yan, Zhao

    2005-06-01

    The long-span bridge response to nonstationary multiple seismic random excitations is investigated using the PEM (pseudo excitation method). This method transforms the nonstationary random response analysis into ordinary direct dynamic analysis, and therefore, the analysis can be solved conveniently using the Newmark, Wilson-θ schemes or the precise integration method. Numerical results of the seismic response for an actual long-span bridge using the proposed PEM are given and compared with the results based on the conventional stationary analysis. From the numerical comparisons, it was found that both the seismic spatial effect and the nonstationary effect are quite important, and that both stationary and nonstationary seismic analysis should pay special attention to the wave passage effect.

  2. Seismic spatial effects on dynamic response of long-span bridges in stationary inhomogeneous random fields

    NASA Astrophysics Data System (ADS)

    Jiahao, Lin; Yahui, Zhang; Yan, Zhao

    2004-12-01

    The seismic analysis of long-span bridges subjected to multiple ground excitations is an important problem. The conventional response spectrum method neglects the spatial effects of ground motion, and therefore may result in questionable conclusions. The random vibration approach has been regarded as more reliable. Unfortunately, so far, computational difficulties have not yet been satisfactorily resolved. In this paper, an accurate and efficient random vibration approach — pseudo excitation method (PEM), by which the above difficulties are overcome, is presented. It has been successfully used in the three dimensional seismic analysis of a number of long-span bridges with thousands of degrees of freedom and dozens of supports. The numerical results of a typical bridge show that the seismic spatial effects, particularly the wave passage effect, are sometimes quite important in evaluating the safety of long-span bridges.

  3. Fixed- and random-effects meta-analytic structural equation modeling: examples and analyses in R.

    PubMed

    Cheung, Mike W-L

    2014-03-01

    Meta-analytic structural equation modeling (MASEM) combines the ideas of meta-analysis and structural equation modeling for the purpose of synthesizing correlation or covariance matrices and fitting structural equation models on the pooled correlation or covariance matrix. Cheung and Chan (Psychological Methods 10:40-64, 2005b, Structural Equation Modeling 16:28-53, 2009) proposed a two-stage structural equation modeling (TSSEM) approach to conducting MASEM that was based on a fixed-effects model by assuming that all studies have the same population correlation or covariance matrices. The main objective of this article is to extend the TSSEM approach to a random-effects model by the inclusion of study-specific random effects. Another objective is to demonstrate the procedures with two examples using the metaSEM package implemented in the R statistical environment. Issues related to and future directions for MASEM are discussed.

  4. Effective fractional acoustic wave equations in one-dimensional random multiscale media.

    PubMed

    Garnier, Josselin; Solna, Knut

    2010-01-01

    This paper considers multiple scattering of waves propagating in a non-lossy one-dimensional random medium with short- or long-range correlations. Using stochastic homogenization theory it is possible to show that pulse propagation is described by an effective deterministic fractional wave equation, which corresponds to an effective medium with a frequency-dependent attenuation that obeys a power law with an exponent between 0 and 2. The exponent is related to the Hurst parameter of the medium, which is a characteristic parameter of the correlation properties of the fluctuations of the random medium. Moreover the frequency-dependent attenuation is associated with a special frequency-dependent phase, which ensures that causality and Kramers-Kronig relations are satisfied. In the time domain the effective wave equation has the form of a linear integro-differential equation with a fractional derivative.

  5. Effective-medium approximation for lattice random walks with long-range jumps

    NASA Astrophysics Data System (ADS)

    Thiel, Felix; Sokolov, Igor M.

    2016-07-01

    We consider the random walk on a lattice with random transition rates and arbitrarily long-range jumps. We employ Bruggeman's effective-medium approximation (EMA) to find the disorder-averaged (coarse-grained) dynamics. The EMA procedure replaces the disordered system with a cleverly guessed reference system in a self-consistent manner. We give necessary conditions on the reference system and discuss possible physical mechanisms of anomalous diffusion. In the case of a power-law scaling between transition rates and distance, lattice variants of Lévy-flights emerge as the effective medium, and the problem is solved analytically, bearing the effective anomalous diffusivity. Finally, we discuss several example distributions and demonstrate very good agreement with numerical simulations.

  6. Effect of Random Thermal Spikes on Stirling Convertor Heater Head Reliability

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Korovaichuk, Igor; Halford, Gary R.

    2004-01-01

    Onboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power converter has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.

  7. Effect of Random Thermal Spikes on Stirling Convertor Heater Head Reliability

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Korovaichuk, Igor; Halford, Gary R.

    2004-01-01

    Onboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power converter has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.

  8. Effect of Random Thermal Spikes on Stirling Convertor Heater Head Reliability

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Korovaichuk, Igor; Halford, Gary R.

    2004-01-01

    Onboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power convertor has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally, assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.

  9. Effects of A-site nonstoichiometry on oxide ion conduction in 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Prasertpalichat, Sasiporn; Schmidt, Whitney; Cann, David P.

    2016-06-01

    Lead free 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 ceramics were prepared by conventional solid-state mixed oxide route with the A-site stoichiometry modified to incorporate donor-doping (through Bi-excess) and acceptor-doping (through Na-excess). Both stoichiometric and nonstoichiometric ceramics exhibited a single perovskite phase with pseudo-cubic symmetry. A significant improvement in the dielectric properties was observed in Bi-excess compositions and a deterioration in the dielectric properties was observed in Na-excess compositions. Impedance spectroscopy was utilized to analyze the effects of A-site nonstoichiometry on conduction mechanisms. Compositions with Bi-excess resulted in an electrically homogeneous microstructure with an increase in resistivity by ˜3-4 orders of magnitude and an associated activation energy of 1.57eV which was close to half of the optical bandgap. In contrast, an electrically heterogeneous microstructure was observed in both the stoichiometric and Na-excess compositions. In addition, the Na-excess compositions exhibited low resistivities (ρ˜103Ω-cm) with characteristic peaks in the impedance data comparable to the recent observations of oxide ion conduction in (Bi0.5Na0.5)TiO3. Long term annealing studies were also conducted at 800∘C to identify changes in crystal structure and electrical properties. The results of this study demonstrates that the dielectric and electrical properties of 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 ceramics are very sensitive to Bi/Na stoichiometry.

  10. A cluster randomized controlled trial of the effectiveness and cost-effectiveness of Intermediate Care Clinics for Diabetes (ICCD): study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background World-wide healthcare systems are faced with an epidemic of type 2 diabetes. In the United Kingdom, clinical care is primarily provided by general practitioners (GPs) rather than hospital specialists. Intermediate care clinics for diabetes (ICCD) potentially provide a model for supporting GPs in their care of people with poorly controlled type 2 diabetes and in their management of cardiovascular risk factors. This study aims to (1) compare patients with type 2 diabetes registered with practices that have access to an ICCD service with those that have access only to usual hospital care; (2) assess the cost-effectiveness of the intervention; and (3) explore the views and experiences of patients, health professionals and other stakeholders. Methods/Design This two-arm cluster randomized controlled trial (with integral economic evaluation and qualitative study) is set in general practices in three UK Primary Care Trusts. Practices are randomized to one of two groups with patients referred to either an ICCD (intervention) or to hospital care (control). Intervention group: GP practices in the intervention arm have the opportunity to refer patients to an ICCD - a multidisciplinary team led by a specialist nurse and a diabetologist. Patients are reviewed and managed in the ICCD for a short period with a goal of improving diabetes and cardiovascular risk factor control and are then referred back to practice. or Control group: Standard GP care, with referral to secondary care as required, but no access to ICCD. Participants are adults aged 18 years or older who have type 2 diabetes that is difficult for their GPs to control. The primary outcome is the proportion of participants reaching three risk factor targets: HbA1c (≤7.0%); blood pressure (<140/80); and cholesterol (<4 mmol/l), at the end of the 18-month intervention period. The main secondary outcomes are the proportion of participants reaching individual risk factor targets and the overall 10-year risks

  11. Extensions of a versatile randomization test for assessing single-case intervention effects.

    PubMed

    Levin, Joel R; Lall, Venessa F; Kratochwill, Thomas R

    2011-02-01

    The purpose of the present study was to investigate the statistical properties of two extensions of the Levin-Wampold (1999) single-case simultaneous start-point model's comparative effectiveness randomization test. The two extensions were (a) adapting the test to situations where there are more than two different intervention conditions and (b) examining the test's performance in classroom-based intervention situations, where the number of time periods (and associated outcome observations) is much smaller than in the contexts for which the test was originally developed. Various Monte Carlo sampling situations were investigated, including from one to five participant blocks per condition and differing numbers of time periods, potential intervention start points, degrees of within-phase autocorrelation, and effect sizes. For all situations, it was found that the Type I error probability of the randomization test was maintained at an acceptable level. With a few notable exceptions, respectable power was observed only in situations where the numbers of observations and potential intervention start points were relatively large, effect sizes were large, and the degree of within-phase autocorrelation was relatively low. It was concluded that the comparative effectiveness randomization test, with its desirable internal validity and statistical-conclusion validity features, is a versatile analytic tool that can be incorporated into a variety of single-case school psychology intervention research situations. Copyright © 2010 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

  12. A note on variance estimation in random effects meta-regression.

    PubMed

    Sidik, Kurex; Jonkman, Jeffrey N

    2005-01-01

    For random effects meta-regression inference, variance estimation for the parameter estimates is discussed. Because estimated weights are used for meta-regression analysis in practice, the assumed or estimated covariance matrix used in meta-regression is not strictly correct, due to possible errors in estimating the weights. Therefore, this note investigates the use of a robust variance estimation approach for obtaining variances of the parameter estimates in random effects meta-regression inference. This method treats the assumed covariance matrix of the effect measure variables as a working covariance matrix. Using an example of meta-analysis data from clinical trials of a vaccine, the robust variance estimation approach is illustrated in comparison with two other methods of variance estimation. A simulation study is presented, comparing the three methods of variance estimation in terms of bias and coverage probability. We find that, despite the seeming suitability of the robust estimator for random effects meta-regression, the improved variance estimator of Knapp and Hartung (2003) yields the best performance among the three estimators, and thus may provide the best protection against errors in the estimated weights.

  13. Effects of selenium supplements on cancer prevention: meta-analysis of randomized controlled trials.

    PubMed

    Lee, Eun-Hyun; Myung, Seung-Kwon; Jeon, Young-Jee; Kim, Yeol; Chang, Yoon Jung; Ju, Woong; Seo, Hong Gwan; Huh, Bong Yul

    2011-11-01

    This meta-analysis aimed to investigate the preventive effect of selenium supplements alone on cancer as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and the Cochrane Library in July 2009. Of the 461 articles searched, 8 articles on 9 RCTs, which included 152,538 total participants, 32,110 in antioxidant supplement groups, and 120,428 in placebo groups, were included. In a random-effects meta-analysis of all 9 RCTs, selenium supplementation alone was found to have an overall preventive effect on cancer incidence [relative risk (RR) = 0.76; 95% confidence interval (CI) = 0.58-0.99]. Among subgroup meta-analyses, the preventive effect of selenium supplementation alone on cancer was apparently observed in populations with a low baseline serum selenium level (<125.6 ng/mL) (RR = 0.64; 95% CI = 0.53 to 0.78; I(2) = 45.5%; n = 7) and in high-risk populations for cancer (RR = 0.68; 95% CI = 0.58 to 0.80; I(2) = 41.5%; n = 8). The meta-analysis of randomized controlled trials indicates that there is possible evidence to support the use of selenium supplements alone for cancer prevention in the low baseline serum selenium level population and in the high-risk population for cancer.

  14. Effect of inter-crystal scatter on estimation methods for random coincidences and subsequent correction.

    PubMed

    Torres-Espallardo, I; Rafecas, M; Spanoudaki, V; McElroy, D P; Ziegler, S I

    2008-05-07

    Random coincidences can contribute substantially to the background in positron emission tomography (PET). Several estimation methods are being used for correcting them. The goal of this study was to investigate the validity of techniques for random coincidence estimation, with various low-energy thresholds (LETs). Simulated singles list-mode data of the MADPET-II small animal PET scanner were used as input. The simulations have been performed using the GATE simulation toolkit. Several sources with different geometries have been employed. We evaluated the number of random events using three methods: delayed window (DW), singles rate (SR) and time histogram fitting (TH). Since the GATE simulations allow random and true coincidences to be distinguished, a comparison between the number of random coincidences estimated using the standard methods and the number obtained using GATE was performed. An overestimation in the number of random events was observed using the DW and SR methods. This overestimation decreases for LETs higher than 255 keV. It is additionally reduced when the single events which have undergone a Compton interaction in crystals before being detected are removed from the data. These two observations lead us to infer that the overestimation is due to inter-crystal scatter. The effect of this mismatch in the reconstructed images is important for quantification because it leads to an underestimation of activity. This was shown using a hot-cold-background source with 3.7 MBq total activity in the background region and a 1.59 MBq total activity in the hot region. For both 200 keV and 400 keV LET, an overestimation of random coincidences for the DW and SR methods was observed, resulting in approximately 1.5% or more (at 200 keV LET: 1.7% for DW and 7% for SR) and less than 1% (at 400 keV LET: both methods) underestimation of activity within the background region. In almost all cases, images obtained by compensating for random events in the reconstruction

  15. The effects of motivation feedback in patients with severe mental illness: a cluster randomized controlled trial

    PubMed Central

    Jochems, Eline C; van der Feltz-Cornelis, Christina M; van Dam, Arno; Duivenvoorden, Hugo J; Mulder, Cornelis L

    2015-01-01

    Objective To evaluate the effectiveness of providing clinicians with regular feedback on the patient’s motivation for treatment in increasing treatment engagement in patients with severe mental illness. Methods Design: cluster randomized controlled trial (Dutch Trials Registry NTR2968). Participants: adult outpatients with a primary diagnosis of a psychotic disorder or a personality disorder and their clinicians, treated in 12 community mental health teams (the clusters) of two mental health institutions in the Netherlands. Interventions: monthly motivation feedback (MF) generated by clinicians additional to treatment as usual (TAU) and TAU by the community mental health teams. Primary outcome: treatment engagement at patient level, assessed at 12 months by clinicians. Randomization: teams were allocated to MF or TAU by a computerized randomization program that randomized each team to a single treatment by blocks of varying size. All participants within these teams received similar treatment. Clinicians and patients were not blind to treatment allocation at the 12-month assessment. Results The 294 randomized patients (148 MF, 146 TAU) and 57 clinicians (29 MF, 28 TAU) of 12 teams (6 MF, 6 TAU) were analyzed according to the intention-to-treat principle. No statistically significant differences between treatment groups on treatment engagement were found (adjusted mean difference =0.1, 95% confidence interval =−2.2 to 2.3, P=0.96, d=0). Preplanned ancillary analyses showed statistically significant interaction effects between treatment group and primary diagnosis on treatment motivation and quality of life (secondary outcomes), which were beneficial for patients with a primary diagnosis of a personality disorder but not for those with a psychotic disorder. There were no reports of adverse events. Conclusion The current findings imply that monitoring and discussing the patient’s motivation is insufficient to improve motivation and treatment engagement, and

  16. Effect of Random Geometric Uncertainty on the Computational Design of a 3-D Flexible Wing

    NASA Technical Reports Server (NTRS)

    Gumbert, C. R.; Newman, P. A.; Hou, G. J.-W.

    2002-01-01

    The effect of geometric uncertainty due to statistically independent, random, normally distributed shape parameters is demonstrated in the computational design of a 3-D flexible wing. A first-order second-moment statistical approximation method is used to propagate the assumed input uncertainty through coupled Euler CFD aerodynamic / finite element structural codes for both analysis and sensitivity analysis. First-order sensitivity derivatives obtained by automatic differentiation are used in the input uncertainty propagation. These propagated uncertainties are then used to perform a robust design of a simple 3-D flexible wing at supercritical flow conditions. The effect of the random input uncertainties is shown by comparison with conventional deterministic design results. Sample results are shown for wing planform, airfoil section, and structural sizing variables.

  17. Effects of random path fluctuations on the accuracy of laser ranging systems.

    PubMed

    Gardner, C S

    1976-10-01

    The effects of turbulence induced pathlength fluctuations on the accuracy of single color and two color laser ranging systems are examined. Correlation and structure functions for the path deviations are derived using several proposed models for the variation of C(n)(2) with altitude. For single color systems, random pathlength fluctuations can limit the accuracy of a range measurement to a few centimeters when the turbulence is strong (C(n)(2) ~ 10(-13) m(-2/3)), and the effective propagation path is long (>10 km). Two color systems can partially correct for the random path fluctuations so that in most cases their accuracy is limited to a few millimeters. However, at low elevation angles for satellite ranging (<20 degrees ) and over long horizontal paths, two color systems can also have errors approaching a few centimeters.

  18. Effect of visual biofeedback to acquire supraglottic swallow in healthy individuals: a randomized-controlled trial.

    PubMed

    Imada, Miho; Kagaya, Hitoshi; Ishiguro, Yuriko; Kato, Miho; Inamoto, Yoko; Tanaka, Takashi; Shibata, Seiko; Saitoh, Eiichi

    2016-06-01

    The aim of this study is to evaluate the effect of visual biofeedback therapy in acquiring supraglottic swallow (SGS) in a randomized-controlled trial with healthy individuals. Eighteen individuals (mean age, 26 years) who could not close or keep closed the vocal folds before and during the swallow in SGS were allocated randomly to either a visual biofeedback group (eight individuals) or a nonbiofeedback group (10 individuals). A videoendoscope was inserted intranasally and an SGS exercise, using 4 ml of green-colored water, was performed 30 times per day up to 5 days. When the participant failed to perform SGS, the result was provided only to the participants in the visual biofeedback group. The median length of time until acquiring SGS was 1.5 days in the visual biofeedback group and 3.5 days in the nonbiofeedback group (P=0.040). We concluded that visual biofeedback effectively enabled participants to acquire SGS earlier.

  19. Reliability of Space-Shuttle Pressure Vessels with Random Batch Effects

    NASA Technical Reports Server (NTRS)

    Feiveson, Alan H.; Kulkarni, Pandurang M.

    2000-01-01

    In this article we revisit the problem of estimating the joint reliability against failure by stress rupture of a group of fiber-wrapped pressure vessels used on Space-Shuttle missions. The available test data were obtained from an experiment conducted at the U.S. Department of Energy Lawrence Livermore Laboratory (LLL) in which scaled-down vessels were subjected to life testing at four accelerated levels of pressure. We estimate the reliability assuming that both the Shuttle and LLL vessels were chosen at random in a two-stage process from an infinite population with spools of fiber as the primary sampling unit. Two main objectives of this work are: (1) to obtain practical estimates of reliability taking into account random spool effects and (2) to obtain a realistic assessment of estimation accuracy under the random model. Here, reliability is calculated in terms of a 'system' of 22 fiber-wrapped pressure vessels, taking into account typical pressures and exposure times experienced by Shuttle vessels. Comparisons are made with previous studies. The main conclusion of this study is that, although point estimates of reliability are still in the 'comfort zone,' it is advisable to plan for replacement of the pressure vessels well before the expected Lifetime of 100 missions per Shuttle Orbiter. Under a random-spool model, there is simply not enough information in the LLL data to provide reasonable assurance that such replacement would not be necessary.

  20. Effects of mass consciousness: changes in random data during global events.

    PubMed

    Nelson, Roger; Bancel, Peter

    2011-01-01

    A long-term, continuing experiment is designed to assess the possibility that correlations may occur in synchronized random data streams generated during major world events. The project is motivated by numerous experiments that suggest that the behavior of random systems can be altered by directed mental intention, and related experiments showing subtle changes associated with group coherence. Since 1998, the Global Consciousness Project (GCP) has maintained a global network of random number generators (RNGs), recording parallel sequences of random data at 65 sites around the world. A rigorous experiment tests the hypothesis that data from the RNG network will deviate from expectation during times of "global events," defined as transitory episodes of widespread mental and emotional reaction to major world events. An ongoing replication experiment measures correlations across the network during the designated events, and the result from over 345 formal hypothesis tests departs substantially from expectation. A composite statistic for the replication series rejects the null hypothesis by more than six standard deviations. Secondary analyses reveal evidence of a second, independent correlation, as well as temporal and spatial structure in the data associated with the events. Controls exclude conventional physical explanations or experimental error as the source of the measured deviations. The experimental design constrains interpretation of the results: they suggest that some aspect of human consciousness is involved as a source of the effects. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Reliability of Space-Shuttle Pressure Vessels with Random Batch Effects

    NASA Technical Reports Server (NTRS)

    Feiveson, Alan H.; Kulkarni, Pandurang M.

    2000-01-01

    In this article we revisit the problem of estimating the joint reliability against failure by stress rupture of a group of fiber-wrapped pressure vessels used on Space-Shuttle missions. The available test data were obtained from an experiment conducted at the U.S. Department of Energy Lawrence Livermore Laboratory (LLL) in which scaled-down vessels were subjected to life testing at four accelerated levels of pressure. We estimate the reliability assuming that both the Shuttle and LLL vessels were chosen at random in a two-stage process from an infinite population with spools of fiber as the primary sampling unit. Two main objectives of this work are: (1) to obtain practical estimates of reliability taking into account random spool effects and (2) to obtain a realistic assessment of estimation accuracy under the random model. Here, reliability is calculated in terms of a 'system' of 22 fiber-wrapped pressure vessels, taking into account typical pressures and exposure times experienced by Shuttle vessels. Comparisons are made with previous studies. The main conclusion of this study is that, although point estimates of reliability are still in the 'comfort zone,' it is advisable to plan for replacement of the pressure vessels well before the expected Lifetime of 100 missions per Shuttle Orbiter. Under a random-spool model, there is simply not enough information in the LLL data to provide reasonable assurance that such replacement would not be necessary.

  2. Cultivating teacher mindfulness: Effects of a randomized controlled trial on work, home, and sleep outcomes.

    PubMed

    Crain, Tori L; Schonert-Reichl, Kimberly A; Roeser, Robert W

    2017-04-01

    The effects of randomization to a workplace mindfulness training (WMT) or a waitlist control condition on teachers' well-being (moods and satisfaction at work and home), quantity of sleep, quality of sleep, and sleepiness during the day were examined in 2 randomized, waitlist controlled trials (RCTs). The combined sample of the 2 RCTs, conducted in Canada and the United States, included 113 elementary and secondary school teachers (89% female). Measures were collected at baseline, postprogram, and 3-month follow-up; teachers were randomly assigned to condition after baseline assessment. Results showed that teachers randomized to WMT reported less frequent bad moods at work and home, greater satisfaction at work and home, more sleep on weekday nights, better quality sleep, and decreased insomnia symptoms and daytime sleepiness. Training-related group differences in mindfulness and rumination on work at home at postprogram partially mediated the reductions in negative moods at home and increases in sleep quality at follow-up. (PsycINFO Database Record

  3. Dosage Effects on School Readiness: Evidence from a Randomized Classroom-Based Intervention

    PubMed Central

    Zhai, Fuhua; Raver, C. Cybele; Jones, Stephanie M.; Li-Grining, Christine P.; Pressler, Emily; Gao, Qin

    2016-01-01

    Variations in the dosage of social interventions and the effects of dosage on program outcomes remain understudied. This study examines the dosage effects of the Chicago School Readiness Project, a randomized, multifaceted classroom-based intervention conducted in Head Start settings. Using a principal score matching method to address the issue of selection bias, the study finds that high-dosage levels of teacher training and mental health consultant class visits have larger effects on children’s school readiness than the effects estimated through intention-to-treat (ITT) analyses. Low-dosage levels of treatment are found to have effects that are smaller than those estimated in ITT analyses or to have no statistically significant program effects. Moreover, individual mental health consultation services provided to high-risk children are found to have statistically significant effects on their school readiness. The study discusses the implications of these findings for research and policy. PMID:21488322

  4. Effect of a mobile app intervention on vegetable consumption in overweight adults: a randomized controlled trial.

    PubMed

    Mummah, Sarah; Robinson, Thomas N; Mathur, Maya; Farzinkhou, Sarah; Sutton, Stephen; Gardner, Christopher D

    2017-09-15

    Mobile applications (apps) have been heralded as transformative tools to deliver behavioral health interventions at scale, but few have been tested in rigorous randomized controlled trials. We tested the effect of a mobile app to increase vegetable consumption among overweight adults attempting weight loss maintenance. Overweight adults (n=135) aged 18-50 years with BMI=28-40 kg/m(2) near Stanford, CA were recruited from an ongoing 12-month weight loss trial (parent trial) and randomly assigned to either the stand-alone, theory-based Vegethon mobile app (enabling goal setting, self-monitoring, and feedback and using "process motivators" including fun, surprise, choice, control, social comparison, and competition) or a wait-listed control condition. The primary outcome was daily vegetables servings, measured by an adapted Harvard food frequency questionnaire (FFQ) 8 weeks post-randomization. Daily vegetable servings from 24-hour dietary recalls, administered by trained, certified, and blinded interviewers 5 weeks post-randomization, was included as a secondary outcome. All analyses were conducted according to principles of intention-to-treat. Daily vegetable consumption was significantly greater in the intervention versus control condition for both measures (adjusted mean difference: 2.0 servings; 95% CI: 0.1, 3.8, p=0.04 for FFQ; and 1.0 servings; 95% CI: 0.2, 1.9; p=0.02 for 24-hour recalls). Baseline vegetable consumption was a significant moderator of intervention effects (p=0.002) in which effects increased as baseline consumption increased. These results demonstrate the efficacy of a mobile app to increase vegetable consumption among overweight adults. Theory-based mobile interventions may present a low-cost, scalable, and effective approach to improving dietary behaviors and preventing associated chronic diseases. ClinicalTrials.gov NCT01826591. Registered 27 March 2013.

  5. Behavioral effects of neurofeedback in adolescents with ADHD: a randomized controlled trial.

    PubMed

    Bink, Marleen; van Nieuwenhuizen, Chijs; Popma, Arne; Bongers, Ilja L; van Boxtel, Geert J M

    2015-09-01

    Neurofeedback has been proposed as a potentially effective intervention for reducing Attention Deficit Hyperactivity Disorder (ADHD) symptoms. However, it remains unclear whether neurofeedback is of additional value to treatment as usual (TAU) for adolescents with clinical ADHD symptoms. Using a multicenter parallel-randomized controlled trial design, adolescents with ADHD symptoms were randomized to receive either a combination of TAU and neurofeedback (NFB + TAU, n = 45) or TAU-only (n = 26). Randomization was computer generated and stratified for age group (ages 12 through 16, 16 through 20, 20 through 24). Neurofeedback treatment consisted of approximately 37 sessions of theta/sensorimotor rhythm (SMR)-training on the vertex (Cz). Primary behavioral outcome measures included the ADHD-rating scale, Youth Self Report, and Child Behavior Checklist all assessed pre- and post-intervention. Behavioral problems decreased equally for both groups with medium to large effect sizes, range of partial η2 = 0.08-0.31, p < 0.05. Hence, the combination of NFB + TAU was not more effective than TAU-only on the behavioral outcome measures. In addition, reported adverse effects were similar for both groups. On behavioral outcome measures, the combination of neurofeedback and TAU was as effective as TAU-only for adolescents with ADHD symptoms. Considering the absence of additional behavioral effects in the current study, in combination with the limited knowledge of specific treatment effects, it is questionable whether theta/SMR neurofeedback for adolescents with ADHD and comorbid disorders in clinical practice should be used. Further research is warranted to investigate possible working mechanisms and (long-term) specific treatment effects of neurofeedback.

  6. Unraveling the effect of La A-site substitution on oxygen ion diffusion and oxygen catalysis in perovskite BaFeO3 by data-mining molecular dynamics and density functional theory.

    PubMed

    Chen, Chi; Baiyee, Zarah Medina; Ciucci, Francesco

    2015-10-07

    BaFeO3 (BFO) is a promising parent material for high-temperature oxygen catalysis. The effects of La substitution on the oxygen ion diffusion and oxygen catalysis in A-site La-substituted BFO are studied by combining data-driven molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The data-driven MD simulations are capable of providing atomic level information regarding oxygen jumps at different sites, bridging the resolution gap of analysis between MD and DFT. The simulations identify several effects due to the introduction of La. First, according to simple electroneutrality considerations and DFT calculations, La tends to decrease the concentration of oxygen vacancies in BFO. Second, La substitution lowers the activation energy of local oxygen migration, providing faster paths for oxygen diffusion. The MD analysis predicts a higher hopping rate through La-containing bottlenecks as well as easier oxygen jumps from the La-rich cages and lower dwell times of oxygen in those cages. DFT calculations confirm a lower migration energy through La-containing bottlenecks. Third, the electrocatalytic activity of the material decreases with La, as indicated by a lower O p-band center and higher oxygen vacancy formation energies.

  7. Gravitational microlensing - The effect of random motion of individual stars in the lensing galaxy

    NASA Technical Reports Server (NTRS)

    Kundic, Tomislav; Wambsganss, Joachim

    1993-01-01

    We investigate the influence of random motion of individual stars in the lensing galaxy on the light curve of a gravitationally lensed background quasar. We compare this with the effects of the transverse motion of the galaxy. We find that three-dimensional random motion of stars with a velocity dispersion sigma in each dimension is more effective in producing 'peaks' in a microlensed light curve by a factor a about 1.3 than motion of the galaxy with a transverse velocity v(t) = sigma. This effectiveness parameter a seems to depend only weakly on the surface mass density. With an assumed transverse velocity of v(t) = 600 km/s of the galaxy lensing the QSO 2237+0305 and a measured velocity dispersion of sigma = 215 km/s, the expected rate of maxima in the light curves calculated for bulk motion alone has to be increased by about 10 percent due to the random motion of stars. As a consequence, the average time interval Delta t between two high-magnification events is smaller than the time interval Delta(t) bulk, calculated for bulk motion alone, Delta t about 0.9 Delta(t) bulk.

  8. The impact of random-effect misspecification on percentile estimation for longitudinal growth data.

    PubMed

    Cheon, Kyeongmi; Albert, Paul S; Zhang, Zhiwei

    2012-12-10

    Identifying unusual growth-related measurements or longitudinal patterns in growth is often the focus in fetal and pediatric medicine. For example, the goal of the ongoing National Fetal Growth Study is to develop both cross-sectional and longitudinal reference curves for ultrasound fetal growth measurements that can be used for this purpose. Current methodology for estimating cross-sectional and longitudinal reference curves relies mainly on the linear mixed model. The focus of this paper is on examining the robustness of percentile estimation to the assumptions with respect to the Gaussian random-effect assumption implicitly made in the standard linear mixed model. We also examine a random-effects distribution based on mixtures of normals and compare the two approaches under both correct and misspecified random-effects distributions. In general, we find that the standard linear mixed model is relatively robust for cross-sectional percentile estimation but less robust for longitudinal or 'personalized' reference curves based on the conditional distribution given prior ultrasound measurements. The methodology is illustrated with data from a longitudinal fetal growth study. Published 2012. This article is a US Government work and is in the public domain in the USA.

  9. Confidence intervals for single-case effect size measures based on randomization test inversion.

    PubMed

    Michiels, Bart; Heyvaert, Mieke; Meulders, Ann; Onghena, Patrick

    2017-02-01

    In the current paper, we present a method to construct nonparametric confidence intervals (CIs) for single-case effect size measures in the context of various single-case designs. We use the relationship between a two-sided statistical hypothesis test at significance level α and a 100 (1 - α) % two-sided CI to construct CIs for any effect size measure θ that contain all point null hypothesis θ values that cannot be rejected by the hypothesis test at significance level α. This method of hypothesis test inversion (HTI) can be employed using a randomization test as the statistical hypothesis test in order to construct a nonparametric CI for θ. We will refer to this procedure as randomization test inversion (RTI). We illustrate RTI in a situation in which θ is the unstandardized and the standardized difference in means between two treatments in a completely randomized single-case design. Additionally, we demonstrate how RTI can be extended to other types of single-case designs. Finally, we discuss a few challenges for RTI as well as possibilities when using the method with other effect size measures, such as rank-based nonoverlap indices. Supplementary to this paper, we provide easy-to-use R code, which allows the user to construct nonparametric CIs according to the proposed method.

  10. Effects of the random single-ion anisotropy and random magnetic field in the spin-3/2 Blume-Capel model

    NASA Astrophysics Data System (ADS)

    da Silva, W. P.; de Arruda, P. H. Z.; Tunes, T. M.; Godoy, M.; de Arruda, A. S.

    2017-01-01

    We have studied the effects of the random single-ion anisotropy and random magnetic field in the phase diagram and in the thermodynamic properties of the spin-3/2 Blume-Capel model via Curie-Weiss mean-field approximation. The phase diagrams were built in the planes temperature versus single-ion anisotropy, temperature versus magnetic field, temperature versus random parameters and the dependencies of magnetization were plotted versus temperature and single-ion anisotropy. These diagrams show that, in the space (D / J - T / J) , the type (first- or second-order) of the phase transition between the ferromagnetic and paramagnetic phases is dependent on the random parameters. Therefore, within these conditions the model presents tricritical behavior. For large values, and a certain critical value of the random parameters, the phase transition is only of second-order, but it is of first-order within the ordered phase, between the phase with m = 1 / 2 and m = 3 / 2 , which ends in a terminal critical point.

  11. Dose-Response Effects of the Text4baby Mobile Health Program: Randomized Controlled Trial

    PubMed Central

    Nielsen, Peter E; Szekely, Daniel R; Bihm, Jasmine W; Murray, Elizabeth A; Snider, Jeremy; Abroms, Lorien C

    2015-01-01

    Background Mobile health (mHealth) is growing rapidly, but more studies are needed on how to optimize programs, including optimal timing of messaging, dose of exposure, and value of interactive features. This study evaluates final outcomes of text4baby (a text message service for pregnant and postpartum women) from a randomized trial performed in a population of pregnant female soldiers and family members. Objective The study aims were to evaluate (1) treatment effects and (2) dose-response effects of text4baby on behavioral outcomes compared to control (no text4baby) condition. Methods The study was a randomized trial of text4baby at Madigan Army Medical Center. Female military health beneficiaries who met inclusion criteria were eligible for the study. Participants provided consent, completed a baseline questionnaire, and then were randomized to enroll in text4baby or not. They were followed up at 3 time points thereafter through delivery of their baby. Generalized estimating equation models were used to evaluate outcomes. We examined treatment effects and the effects of higher doses of text4baby messages on outcomes. Results We report descriptive statistics including dosage of text messages delivered. The main finding was a significant effect of high exposure to text4baby on self-reported alcohol consumption postpartum (OR 0.212, 95% CI 0.046-0.973, P=.046), as measured by the question “Since you found out about your pregnancy, have you consumed alcoholic beverages?” The text4baby participants also reported lower quantities of alcohol consumed postpartum. Conclusions Studies of text4baby have helped to build the mHealth evidence base. The effects of text4baby offer lessons for future scalable mHealth programs and suggest the need to study dose-response effects of these interventions. PMID:25630361

  12. The Effect of Blocked, Random and Mixed Practice Schedules on Speech Motor Learning of Tongue Twisters in Unimpaired Speakers.

    PubMed

    Jones, Kelly; Croot, Karen

    2016-10-01

    There are few investigations comparing practice schedules in speech motor learning, despite certain schedules being recommended for the clinical treatment of speech motor disorders. This study compared effects of random, blocked and mixed practice on tongue twister accuracy in unimpaired speakers. We hypothesized that blocked practice would benefit acquisition of learning, but that random practice and mixed blocked-then-random practice would yield superior retention of learning. We found that the random and blocked-random practice schedules yielded superior accuracy at the end of the acquisition phase of learning and at a 1-week retention test. Exploratory post hoc analyses raised the possibility that the retention effects were most evident when tongue twisters were elicited in a random schedule. Theoretical accounts of these results are discussed.

  13. Be skeptical about unexpected large apparent treatment effects: the case of an MRC AML12 randomization.

    PubMed

    Wheatley, Keith; Clayton, David

    2003-02-01

    The preliminary results of the twelfth Medical Research Council acute myeloid leukemia trial show no evidence of a survival advantage for five courses of therapy compared to four courses in a randomized comparison involving 1078 patients (hazard ratio 1.09, 95% confidence interval [CI] 0.87-1.37, p=0.4). However, the data presented to the independent data monitoring and ethics committee (DMEC) at both its reviews in 1998 suggested large benefits for the additional course with hazard ratios of 0.47 and 0.55 (95% CIs 0.29-0.77 and 0.38-0.80, p=0.003 and p=0.002, respectively). Despite these highly significant findings, the DMEC did not recommend closure of the randomization, a decision vindicated by the subsequent reversion to a null result. The main reason for not closing the randomization was that the treatment effects observed in 1998 (53% and 45% reductions in the odds of death) were considered too large to be clinically plausible, despite the p-values associated with them. Investigations have not identified any clinical explanations, such as different types of patients in the early and later parts of the trial, to explain the loss of benefit as the trial progressed. Thus, the most likely current explanation for the large benefit observed early on is the play of chance. Lessons to be learned from this example are that: fixed stopping rules based on some predetermined p-value should not be used and the decision to close a randomization or not should take account of other factors such as the medical plausibility of the magnitude of the treatment effect; chance effects do occur and happen more frequently than many clinicians realize; it is important that DMEC members are experienced in the interpretation of clinical trial evidence and aware of the dangers of early stopping without wholly convincing evidence.

  14. No Effect of Aspirin on Mammographic Density in a Randomized Controlled Clinical Trial

    PubMed Central

    McTiernan, Anne; Wang, CY; Sorensen, Bess; Xiao, Liren; Buist, Diana S. M.; Bowles, Erin J. Aiello; White, Emily; Rossing, Mary Anne; Potter, John; Urban, Nicole

    2009-01-01

    Background: Epidemiologic studies suggest a reduced risk of breast cancer among women who regularly use aspirin; a plausible mechanism is through aspirin effect on mammographic breast density, a breast cancer risk factor, possibly mediated through aspirin interference with estrogen synthesis. Methods: In a 2-arm randomized placebo-controlled clinical trial, we evaluated the effects of 6-months administration of 325 mg/day aspirin on total mammographic breast dense area and percent of the mammographic breast image occupied by dense areas (% density) in 143 postmenopausal women. Eligible women, recruited 2005-7, were healthy, not taking hormone therapy, with elevated mammographic breast density (American College of Radiology Breast Imaging Reporting and Data System (BI-RADS®) density category 2, 3 or 4) within 6 months prior to enrollment. Results: Women were a mean (s.d.) 59.5 (5.5) years. Geometric mean baseline percent density was 17.6% (95% CI 14.8, 20.9) in women randomized to aspirin and 19.2% (95% CI 16.3, 22.7) in women randomized to placebo. Percent density decreased in women randomized to aspirin by an absolute 0.8% vs. an absolute decrease of 1.2% in controls (p = 0.84). Total breast area and dense area decreased to a similar degree in women assigned to aspirin and in those assigned to placebo, with no differences statistically significantly different between trial arms. Conclusions: A single daily administration of adult-dose aspirin for 6 months had no effect on mammographic density in postmenopausal women. If aspirin affects breast cancer risk in postmenopausal women, it may do so through alternative pathways than mammographic breast density. PMID:19423529

  15. Random fluctuations and validity in measuring disease management effectiveness for small populations.

    PubMed

    Farah, J Ramsay; Kamali, Kyahn; Harner, Jeffrey; Duncan, Ian G; Messer, Thomas C

    2008-12-01

    One objective of a disease management (DM) program is the reduction of members' claims costs. A considerable amount of effort has been dedicated to standardizing the outcomes of DM measurement. An area that has not received as much attention is that of random fluctuations in measured outcomes and the related issue of the validity of outcomes subject to random fluctuation. From year to year, large random fluctuations in claims costs can increase or reduce actual savings from a DM program. Sponsors of DM programs want to know how large a group or sample is necessary to prevent the effect of random fluctuations from overwhelming the effect of claims reductions. In this paper, we measure the fluctuations in calculated DM savings in a large commercial population using an adjusted historical control methodology--the methodology that has become the industry standard and which is codified by DMAA's Guidelines. We then determine the sample size necessary to demonstrate DM program savings at different levels of confidence and model the effect on fluctuations in observed outcomes under different methods of choosing trend, different levels of truncation, and for different estimates of program savings. Some groups, particularly employers, will be smaller than the minimum size required for credible outcomes measurement. For groups smaller than this minimum size, we suggest a utilization-based outcomes measure that can be used as a proxy. For both claims- and utilization-based calculations, we provide confidence intervals to be placed around savings estimates. We do this for group sizes ranging from 1000 to 100,000 members.

  16. Randomized Controlled Trial of Social Media: Effect of Increased Intensity of the Intervention.

    PubMed

    Fox, Caroline S; Gurary, Ellen B; Ryan, John; Bonaca, Marc; Barry, Karen; Loscalzo, Joseph; Massaro, Joseph

    2016-04-27

    A prior randomized controlled trial of social media exposure at Circulation determined that social media did not increase 30-day page views. Whether insufficient social media intensity contributed to these results is uncertain. Original article manuscripts were randomized to social media exposure compared with no social media exposure (control) at Circulation beginning in January 2015. Social media exposure consisted of Facebook and Twitter posts on the journal's accounts. To increase social media intensity, a larger base of followers was built using advertising and organic growth, and posts were presented in triplicate and boosted on Facebook and retweeted on Twitter. The primary outcome was 30-day page views. Stopping rules were established at the point that 50% of the manuscripts were randomized and had 30-day follow-up to compare groups on 30-day page views. The trial was stopped for futility on September 26, 2015. Overall, 74 manuscripts were randomized to receive social media exposure, and 78 manuscripts were randomized to the control arm. The intervention and control arms were similar based on article type (P=0.85), geographic location of the corresponding author (P=0.33), and whether the manuscript had an editorial (P=0.80). Median number of 30-day page views was 499.5 in the social media arm and 450.5 in the control arm; there was no evidence of a treatment effect (P=0.38). There were no statistically significant interactions of treatment by manuscript type (P=0.86), by corresponding author (P=0.35), by trimester of publication date (P=0.34), or by editorial status (P=0.79). A more intensive social media strategy did not result in increased 30-day page views of original research. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  17. Effect of Co Substitution on the Crystal and Magnetic Structure of SrFeO2.75-δ: Stabilization of the "314-Type" Oxygen Vacancy Ordered Structure without A-Site Ordering.

    PubMed

    Marik, Sourav; Chennabasappa, Madhu; Fernández-Sanjulián, Javier; Petit, Emmanuel; Toulemonde, Olivier

    2016-10-03

    A study of the structure-composition-properties correlation is reported for the oxygen-deficient SrFe1-xCoxO2.75-δ (x = 0.1-0.85) materials. The introduction of Co in the parent SrFeO2.75 (Sr4Fe4O11) structure revealed an interesting structural transformation. At room temperature (RT), an orthorhombic (space group Cmmm, 2√2ap × 2ap × √2ap type, ap = lattice parameter of the cubic perovskite) → tetragonal (space group P4/mmm, ap × ap × 2ap type) → tetragonal (space group I4/mmm, 2ap × 2ap × 4ap type) structural transformation is observed in parallel with increasing Co content and decreasing oxygen content in the structure. At the same time, a rich variation in the magnetic properties is explored. The samples with x = 0.25, 0.3 show temperature-induced magnetization reversal. With increasing Co content in the structure, magnetic interactions start to weaken due to the random distribution of Fe and Co in the structure; the x = 0.5 sample shows frustration in the magnetic behavior with much smaller magnetization value. With a further increase in the Co content in the structure, RT ferrimagnetic-type behavior is observed for the sample with x = 0.85. The nuclear and magnetic structure refinements using RT and low-temperature neutron powder diffraction (NPD, 10 K) patterns confirm the formation of a "314-type" novel oxygen vacancy ordered phase for the sample with x = 0.85, which is the first case of "314-type" novel oxygen vacancy ordering without A-site (ABO3-δ type perovskite) ordering. The magnetic structure is G-type antiferromagnetic starting at room temperature. Further, the stabilization of the "314-type" complex superstructure is related to the ordering of oxygen vacancies in the oxygen-deficient Co-O layers, and the same assists in building a network of Co ions with different coordination environments, each with different spin states, and forms the spin-state ordering.

  18. Comparative effectiveness of childhood obesity interventions in pediatric primary care: a cluster-randomized clinical trial.

    PubMed

    Taveras, Elsie M; Marshall, Richard; Kleinman, Ken P; Gillman, Matthew W; Hacker, Karen; Horan, Christine M; Smith, Renata L; Price, Sarah; Sharifi, Mona; Rifas-Shiman, Sheryl L; Simon, Steven R

    2015-06-01

    Evidence of effective treatment of childhood obesity in primary care settings is limited. To examine the extent to which computerized clinical decision support (CDS) delivered to pediatric clinicians at the point of care of obese children, with or without individualized family coaching, improved body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) and quality of care. We conducted a cluster-randomized, 3-arm clinical trial. We enrolled 549 children aged 6 to 12 years with a BMI at the 95% percentile or higher from 14 primary care practices in Massachusetts from October 1, 2011, through June 30, 2012. Patients were followed up for 1 year (last follow-up, August 30, 2013). In intent-to-treat analyses, we used linear mixed-effects models to account for clustering by practice and within each person. In 5 practices randomized to CDS, pediatric clinicians received decision support on obesity management, and patients and their families received an intervention for self-guided behavior change. In 5 practices randomized to CDS + coaching, decision support was augmented by individualized family coaching. The remaining 4 practices were randomized to usual care. Smaller age-associated change in BMI and the Healthcare Effectiveness Data and Information Set (HEDIS) performance measures for obesity during the 1-year follow-up. At baseline, mean (SD) patient age and BMI were 9.8 (1.9) years and 25.8 (4.3), respectively. At 1 year, we obtained BMI from 518 children (94.4%) and HEDIS measures from 491 visits (89.4%). The 3 randomization arms had different effects on BMI over time (P = .04). Compared with the usual care arm, BMI increased less in children in the CDS arm during 1 year (-0.51 [95% CI, -0.91 to -0.11]). The CDS + coaching arm had a smaller magnitude of effect (-0.34 [95% CI, -0.75 to 0.07]). We found substantially greater achievement of childhood obesity HEDIS measures in the CDS arm (adjusted odds ratio, 2.28 [95% CI, 1

  19. Estimating causal effects from a randomized clinical trial when noncompliance is measured with error.

    PubMed

    Boatman, Jeffrey A; Vock, David M; Koopmeiners, Joseph S; Donny, Eric C

    2017-06-12

    Noncompliance or non-adherence to randomized treatment is a common challenge when interpreting data from randomized clinical trials. The effect of an intervention if all participants were forced to comply with the assigned treatment (i.e., the causal effect) is often of primary scientific interest. For example, in trials of very low nicotine content (VLNC) cigarettes, policymakers are interested in their effect on smoking behavior if their use were to be compelled by regulation. A variety of statistical methods to estimate the causal effect of an intervention have been proposed, but these methods, including inverse probability of compliance weighted (IPCW) estimators, assume that participants' compliance statuses are reported without error. This is an untenable assumption when compliance is based on self-report. Biomarkers (e.g., nicotine levels in the urine) may provide more reliable indicators of compliance but cannot perfectly discriminate between compliers and non-compliers. However, by modeling the distribution of the biomarker as a mixture distribution and writing the probability of compliance as a function of the mixture components, we show how the probability of compliance can be directly estimated from the data even when compliance status is unknown. To estimate the causal effect, we develop a new approach which re-weights participants by the product of their probability of compliance given the observed data and the inverse probability of compliance given confounders. We show that our proposed estimator is consistent and asymptotically normal and show that in some situations the proposed approach is more efficient than standard IPCW estimators. We demonstrate via simulation that the proposed estimator achieves smaller bias and greater efficiency than ad hoc approaches to estimating the causal effect when compliance is measured with error. We apply our method to data from a recently completed randomized trial of VLNC cigarettes. © The Author 2017

  20. An effective group psychoeducational intervention for improving compliance with vaginal dilation: A randomized controlled trial

    SciTech Connect

    Jeffries, Sherryl A.; Robinson, John W. . E-mail: johnrobi@cancerboard.ab.ca; Craighead, Peter S.; Keats, Melanie R.

    2006-06-01

    Purpose: Although vaginal dilation is often recommended to minimize or prevent vaginal scarring after pelvic radiotherapy, compliance with this recommendation has historically been very low. Therefore, effective intervention strategies are needed to enhance compliance with vaginal dilation after radiotherapy for gynecologic cancer. Methods and Materials: This study was a randomized controlled clinical trial of a psychoeducational intervention specifically designed to increase compliance with vaginal dilation. The information-motivation-behavioral skills model of enhancing compliance with behavioral change was the basis for the intervention design. Forty-two sexually active women, 21 to 65 years of age, diagnosed with Stages Ic-III cervical or endometrial cancer, who received pelvic radiotherapy, were randomized to either the experimental psychoeducational group or the information-only control group. Assessment via questionnaire occurred before treatment and at 6-week, 6-month, 12-month, 18-month, and 24-month follow-up. Assessment via interview also occurred at 6-month, 12-month, 18-month, and 24-month follow-up. Results: The psychoeducational intervention was successful in increasing compliance with vaginal dilation. Conclusions: This study is the first randomized controlled study to demonstrate the effectiveness of an intervention in increasing compliance with the use of vaginal dilators.

  1. A randomized study of the effect of carbonated water prior to myocardial SPECT.

    PubMed

    Vermeltfoort, Ilse A C; van Dijk, Arjan B; de Jong, Jeroen A F; Teule, Gerrit J J; Gevers, Marjon; Verhoeven, Bas; Raaijmakers, Esther; Knaapen, Paul; Raijmakers, Pieter G H M

    2014-08-01

    In myocardial perfusion single-photon emission computed tomography (SPECT), abdominal activity often interferes with the evaluation of perfusion in the inferior wall, especially after pharmacological stress. In this randomized study, we examined the effect of carbonated water intake versus still water intake on the quality of images obtained during myocardial perfusion images (MPI) studies. A total of 467 MIBI studies were randomized into a carbonated water group and a water group. The presence of intestinal activity adjacent to the inferior wall was evaluated by two observers. Furthermore, a semi-quantitative analysis was performed in the adenosine subgroup, using a count ratio of the inferior myocardial wall and adjacent abdominal activity. The need for repeated SPECT in the adenosine studies was 5.3% in the carbonated water group versus 19.4% in the still water group (p = 0.019). The inferior wall-to-abdomen count ratio was significantly higher in the carbonated water group compared to the still water group (2.11 ± 1.00 vs. 1.72 ± 0.73, p < 0.001). The effect of carbonated water during rest and after exercise was not significant. This randomized study showed that carbonated water significantly reduced the interference of extra-cardiac activity in adenosine SPECT MPI.

  2. Effects of prenatal yoga on women's stress and immune function across pregnancy: A randomized controlled trial.

    PubMed

    Chen, Pao-Ju; Yang, Luke; Chou, Cheng-Chen; Li, Chia-Chi; Chang, Yu-Cune; Liaw, Jen-Jiuan

    2017-04-01

    The effects of prenatal yoga on biological indicators have not been widely studied. Thus, we compared changes in stress and immunity salivary biomarkers from 16 to 36 weeks' gestation between women receiving prenatal yoga and those receiving routine prenatal care. For this longitudinal, prospective, randomized controlled trial, we recruited 94 healthy pregnant women at 16 weeks' gestation through convenience sampling from a prenatal clinic in Taipei. Participants were randomly assigned to intervention (n=48) or control (n=46) groups using Clinstat block randomization. The 20-week intervention comprised two weekly 70-min yoga sessions led by a midwife certified as a yoga instructor; the control group received only routine prenatal care. In both groups, participants' salivary cortisol and immunoglobulin A levels were collected before and after yoga every 4 weeks from 16 to 36 weeks' gestation. The intervention group had lower salivary cortisol (p<0.001) and higher immunoglobulin A (p<0.001) levels immediately after yoga than the control group. Specifically, the intervention group had significantly higher long-term salivary immunoglobulin A levels than the control group (p=0.018), and infants born to women in the intervention group weighed more than those born to the control group (p<0.001). Prenatal yoga significantly reduced pregnant women's stress and enhanced their immune function. Clinicians should learn the mechanisms of yoga and its effects on pregnant women. Our findings can guide clinicians to help pregnant women alleviate their stress and enhance their immune function. Copyright © 2017. Published by Elsevier Ltd.

  3. Bending and elongation effects on the random packing of curved spherocylinders.

    PubMed

    Meng, Lingyi; Li, Shuixiang; Lu, Peng; Li, Teng; Jin, Weiwei

    2012-12-01

    Studies on the macroscopic and microscopic packing properties of nonconvex particles are scarce. As a common concave form, the curved spherocylinder is used in the simulations, and its bending and elongation effects on the random packings are investigated numerically with sphere assembly models and a relaxation algorithm. The aspect ratio is demonstrated to be the main factor regarding the packing density. However, at certain aspect ratios of low densities around 0.3-0.4, the density of curved spherocylinders may increase by 15% more than that of the straight ones, indicating that bending is also a contributor to the packing density. The excluded volume of the curved spherocylinder decreases with the increase of the bending angle, indicating that the excluded volume is applicable in explaining the bending effect on the packing density variation of nonconvex particles. The packings are verified to be randomly distributed in orientation with no significant layering or in-plane order. The local arrangements are further analyzed from the radial distribution function and contact results. The results show that the random packings of nonconvex particles have significant differences and richer characteristics on both the macroscopic and microscopic properties compared with convex objects.

  4. A Randomized Effectiveness Trial of Interpersonal Psychotherapy for Depressed Women With Sexual Abuse Histories

    PubMed Central

    Talbot, Nancy L.; Chaudron, Linda H.; Ward, Erin A.; Duberstein, Paul R.; Conwell, Yeates; O’Hara, Michael W.; Tu, Xin; Lu, Naiji; He, Hua; Stuart, Scott

    2011-01-01

    Objectives Many depressed women seen in community mental health centers (CMHCs) have histories of childhood sexual abuse and are economically disadvantaged. Randomized trials are needed to test the effectiveness of evidence-based interventions in this population and setting. This study compared interpersonal psychotherapy with usual care psychotherapy among women in a CMHC. Methods Among 1,100 women seeking treatment in a CMHC, 230 (21%) had major depression and histories of childhood sexual abuse. Seventy women with major depression and sexual abuse before age 18 were randomly assigned to interpersonal psychotherapy (N=37) or usual care psychotherapy (N=33). Staff clinicians provided all treatments. Participants were assessed at study entry and at ten, 24, and 36 weeks after random assignment. Generalized estimating equations were used to examine change over time. Results Compared with women assigned to usual care, women who received interpersonal psychotherapy had greater reductions in depressive symptoms (Hamilton Rating Scale, p=.05, d=.34; Beck Depression Inventory–II, p=.01, d=.29), posttraumatic stress disorder symptoms (p=.04, d=.76), and shame (p=.002, d=.38). Interpersonal psychotherapy and usual care yielded comparable improvements in social and mental health–related functioning. Conclusions Interpersonal psychotherapy compared favorably to usual care psychotherapy in a CMHC in improving psychiatric symptoms and reducing shame among sexually abused women. However, there is a critical need for continued research to develop more effective treatments for the social and psychiatric sequelae of interpersonal trauma and socioeconomic disadvantage. PMID:21459988

  5. Effects of Vitamin D Intake on FEV1 and COPD Exacerbation: A Randomized Clinical Trial Study

    PubMed Central

    Zendedel, Abolfazl; Gholami, Mohammadreza; Anbari, Khatereh; Ghanadi, Kourosh; Bachari, Elham Ceneicel; Azargon, Alireza

    2015-01-01

    Aim: This study aimed to evaluate the effects of vitamin D intake on COPD exacerbation and FEV1 in the patients with severe and very severe COPD. Methods: This double blind placebo control randomized clinical trial study was done in the Ashayer university hospital in Khorramabad in 2012. Eighty eight patients with severe and very severe COPD were randomly selected from those who recoursed to the internal medicine clinic of Ashayer hospital. They were randomly allocated to case and placebo group. The patients received routine treatment for COPD. Along with the routine treatment, placebo group received 100,000 IU of oral vitamin D per month, for 6 months. Data was analyzed using SPSS computer software, paired t-test, independent t-test, non parametric t-test and Pearson correlation coefficients. Results: In each group, there were 44 patients. After the intervention, there were significant differences in FEV1 and the number of COPD exacerbation between the case and control group patients. Also, after the study, in the case group, FEV1 was increased and the number of COPD exacerbation was decreased significantly. Conclusion: Vitamin D intake decreased COPD exacerbation and improved FEV1 in the patients with severe and very severe COPD. It is suggested that baseline serum vitamin D levels will recorded in similar studies and the effect of vitamin D intake will evaluated regarding the baseline serum vitamin D levels. PMID:25946929

  6. Components of effective randomized controlled trials of hydrotherapy programs for fibromyalgia syndrome: A systematic review.

    PubMed

    Perraton, Luke; Machotka, Zuzana; Kumar, Saravana

    2009-11-30

    Previous systematic reviews have found hydrotherapy to be an effective management strategy for fibromyalgia syndrome (FMS). The aim of this systematic review was to summarize the components of hydrotherapy programs used in randomized controlled trials. A systematic review of randomized controlled trials was conducted. Only trials that have reported significant FMS-related outcomes were included. Data relating to the components of hydrotherapy programs (exercise type, duration, frequency and intensity, environmental factors, and service delivery) were analyzed. Eleven randomized controlled trials were included in this review. Overall, the quality of trials was good. Aerobic exercise featured in all 11 trials and the majority of hydrotherapy programs included either a strengthening or flexibility component. Great variability was noted in both the environmental components of hydrotherapy programs and service delivery. Aerobic exercise, warm up and cool-down periods and relaxation exercises are common features of hydrotherapy programs that report significant FMS-related outcomes. Treatment duration of 60 minutes, frequency of three sessions per week and an intensity equivalent to 60%-80% maximum heart rate were the most commonly reported exercise components. Exercise appears to be the most important component of an effective hydrotherapy program for FMS, particularly when considering mental health-related outcomes.

  7. Components of effective randomized controlled trials of hydrotherapy programs for fibromyalgia syndrome: A systematic review

    PubMed Central

    Perraton, Luke; Machotka, Zuzana; Kumar, Saravana

    2009-01-01

    Aim Previous systematic reviews have found hydrotherapy to be an effective management strategy for fibromyalgia syndrome (FMS). The aim of this systematic review was to summarize the components of hydrotherapy programs used in randomized controlled trials. Method A systematic review of randomized controlled trials was conducted. Only trials that have reported significant FMS-related outcomes were included. Data relating to the components of hydrotherapy programs (exercise type, duration, frequency and intensity, environmental factors, and service delivery) were analyzed. Results Eleven randomized controlled trials were included in this review. Overall, the quality of trials was good. Aerobic exercise featured in all 11 trials and the majority of hydrotherapy programs included either a strengthening or flexibility component. Great variability was noted in both the environmental components of hydrotherapy programs and service delivery. Conclusions Aerobic exercise, warm up and cool-down periods and relaxation exercises are common features of hydrotherapy programs that report significant FMS-related outcomes. Treatment duration of 60 minutes, frequency of three sessions per week and an intensity equivalent to 60%–80% maximum heart rate were the most commonly reported exercise components. Exercise appears to be the most important component of an effective hydrotherapy program for FMS, particularly when considering mental health-related outcomes. PMID:21197303

  8. Random effects in censored ordinal regression: latent structure and Bayesian approach.

    PubMed

    Xie, M; Simpson, D G; Carroll, R J

    2000-06-01

    This paper discusses random effects in censored ordinal regression and presents a Gibbs sampling approach to fit the regression model. A latent structure and its corresponding Bayesian formulation are introduced to effectively deal with heterogeneous and censored ordinal observations. This work is motivated by the need to analyze interval-censored ordinal data from multiple studies in toxicological risk assessment. Application of our methodology to the data offers further support to the conclusions developed earlier using GEE methods yet provides additional insight into the uncertainty levels of the risk estimates.

  9. Core polarization effects in the Hartree--Fock--random phase approximation schemes

    SciTech Connect

    Lipparini, E.; Stringari, S.

    1987-02-01

    Core polarization effects in odd nuclei are investigated in the framework of the Hartree--Fock and random phase approximation schemes. The results of the particle vibration coupling model are recovered by linearizing the equations of motion in the interaction Hamiltonian between the external and the core particles. The formalism is used to study the renormalization of diagonal and off-diagonal M1 matrix elements. It is found that M1 polarization effects exhibit a very strong dependence on the range of the force. Copyright 1987 Academic Press, Inc.

  10. The effects of metoclopramide on postoperative ileus. A randomized double-blind study.

    PubMed Central

    Davidson, E D; Hersh, T; Brinner, R A; Barnett, S M; Boyle, L P

    1979-01-01

    Metoclopramide or placebo was administered postoperatively in a randomized, double-blind fashion to 115 patients undergoing laparotomy. The effect of metoclopramide on postoperative adynamic ileus (PAI) was evaluated. The patients were stratified into two groups: Group A--those with laparotomy without a gastrointestinal anastomosis or ostomy procedure, and group B--those with laparotomy undergoing an anastomosis or ostomy procedure. Metoclopramide reduced nausea and emesis postoperatively. However, the only significant effect on postoperative adynamic ileus was an earlier return to tolerance of solid foods in the patients in Group A. PMID:582360

  11. Covert communications using random noise signals: effects of atmospheric propagation nulls and rain

    NASA Astrophysics Data System (ADS)

    Mohan, Karen M.; Narayanan, Ram M.

    2005-06-01

    In military communications, there exist numerous potential threats to message security. Ultra-wideband (UWB) signals provide secure communications because they cannot, in general, be detected using conventional receivers and they can be made relatively immune from jamming. The security of an UWB signal can be further improved by mixing it with random noise. By using a random noise signal, the user can conceal the message signal within the noise waveform and thwart detection by hostile forces. This paper describes a novel spread spectrum technique that can be used for secure and covert communications. The technique is based on the use of heterodyne correlation techniques to inject coherence in a random noise signal. The modulated signal to be transmitted containing the coherent carrier is mixed with a sample of an ultra-wideband (UWB) random noise signal. The frequency range of the UWB noise signal is appropriately chosen so that the lower sideband of the mixing process falls over the same frequency range. Both the frequency-converted noise-like signal and the original random noise signal are simultaneously transmitted on orthogonally polarized channels through a dual-polarized transmitting antenna. The receiver consists of a similar dual-polarized antenna that simultaneously receives the two orthogonally polarized transmitted signals, amplifies each in a minimum phase limiting amplifier, and mixes these signals in a double sideband upconverter. The upper sideband of the mixing process recovers the modulated signal, which can then be demodulated. The advantage of this technique lies in the relative immunity of the random noise-like unpolarized transmit signal from detection and jamming. Since the transmitted signal "appears" totally unpolarized and noise-like, linearly polarized receivers are unable to identify, decode, or otherwise extract useful information from the signal. The system is immune from interference caused by high power linearly polarized signal

  12. Effects of Physical Activity on Poststroke Cognitive Function: A Meta-Analysis of Randomized Controlled Trials.

    PubMed

    Oberlin, Lauren E; Waiwood, Aashna M; Cumming, Toby B; Marsland, Anna L; Bernhardt, Julie; Erickson, Kirk I

    2017-09-20

    Despite the social, health, and economic burdens associated with cognitive impairment poststroke, there is considerable uncertainty about the types of interventions that might preserve or restore cognitive abilities. The objective of this systematic review and meta-analysis was to evaluate the effects of physical activity (PA) training on cognitive function poststroke and identify intervention and sample characteristics that may moderate treatment effects. Randomized controlled trials examining the association between structured PA training and cognitive performance poststroke were identified using electronic databases EMBASE and MEDLINE. Intervention effects were represented by Hedges' g and combined into pooled effect sizes using random- and mixed-effects models. Effect sizes were subjected to moderation analyses using the between-group heterogeneity test. Fourteen studies met inclusion criteria, representing data from 736 participants. The primary analysis yielded a positive overall effect of PA training on cognitive performance (Hedges' g [95% confidence interval]=0.304 [0.14-0.47]). Mixed-effects analyses demonstrated that combined aerobic and strength training programs generated the largest cognitive gains and that improvements in cognitive performance were achieved even in the chronic stroke phase (mean=2.6 years poststroke). Positive moderate treatment effects were found for attention/processing speed measures (Hedges' g [confidence interval]=0.37 [0.10-0.63]), while the executive function and working memory domains did not reach significance (P>0.05). We found a significant positive effect of PA training on cognition poststroke with small to moderate treatment effects that are apparent even in the chronic stroke phase. Our findings support the use of PA training as a treatment strategy to promote cognitive recovery in stroke survivors. © 2017 American Heart Association, Inc.

  13. Effects of online cognitive treatment for problematic anger: a randomized controlled trial.

    PubMed

    Howie, Amanda J; Malouff, John M

    2014-01-01

    Problematic anger, which is common, has been associated with a wide range of negative interpersonal and intrapersonal consequences, including violent behaviour, relationship damage, health problems and low self-esteem. This article reports the results of the first randomized controlled trial of brief online cognitive treatment for anger. The sample included 75 adults who were randomly assigned to cognitive treatment or a waiting list control. The analyses with the 59 participants who completed the post-intervention assessment at four weeks after the beginning of the intervention showed that individuals who received the intervention reported significantly lower anger levels than the control group at post-assessment. The treatment group showed a substantial decrease in anger from pre to post. The results suggest that brief online cognitive treatment can be effective for reducing problematic anger in adults. These findings provide an initial support for the development of internet-based cognitive treatment for problematic anger.

  14. Effects of 3D random correlated velocity perturbations on predicted ground motions

    USGS Publications Warehouse

    Hartzell, S.; Harmsen, S.; Frankel, A.

    2010-01-01

    Three-dimensional, finite-difference simulations of a realistic finite-fault rupture on the southern Hayward fault are used to evaluate the effects of random, correlated velocity perturbations on predicted ground motions. Velocity perturbations are added to a three-dimensional (3D) regional seismic velocity model of the San Francisco Bay Area using a 3D von Karman random medium. Velocity correlation lengths of 5 and 10 km and standard deviations in the velocity of 5% and 10% are considered. The results show that significant deviations in predicted ground velocities are seen in the calculated frequency range (≤1 Hz) for standard deviations in velocity of 5% to 10%. These results have implications for the practical limits on the accuracy of scenario ground-motion calculations and on retrieval of source parameters using higher-frequency, strong-motion data.

  15. Effectiveness of acupuncture for the initiation of labour at term: a pilot randomized controlled trial.

    PubMed

    Gaudet, Laura M; Dyzak, Randal; Aung, Steven K H; Smith, Graeme N

    2008-12-01

    This study was designed to determine the effectiveness of acupuncture for the initiation of labour in women at term. A prospective pilot randomized control trial was undertaken, in which 16 pregnant women at term were randomly assigned to receive acupuncture either at sites reported to cause onset of labour or at nearby sham sites. The primary outcome assessed was the interval from initial acupuncture treatment to delivery. There was a difference in intervention to delivery interval of 62 hours in favour of the treatment group. Furthermore, women in this group had shorter labours by a mean of 2 hours and 20 minutes. The interesting results of this pilot trial warrant further investigation into the use of acupuncture for the initiation of labour in women at term.

  16. Effects of a random porosity model on double diffusive natural convection in a porous medium enclosure

    SciTech Connect

    Fu, W.S.; Ke, W.W.

    2000-01-01

    A double diffusive natural convection in a rectangular enclosure filled with porous medium is investigated numerically. The distribution of porosity is based upon the random porosity model. The Darcy-Brinkman-Forchheimer model is used and the factors of heat flux, mean porosity and standard deviation are taken into consideration. The SIMPLEC method with iterative processes is adopted to solve the governing equations. The effects of the random porosity model on the distributions of local Nusselt number are remarkable and the variations of the local Nusselt number become disordered. The contribution of latent heat transfer to the total heat transfer of the high Rayleigh number is larger than that of the low Rayleigh number and the variations of the latent heat transfer are not in order.

  17. Effect of Rosa damascene aromatherapy on sleep quality in cardiac patients: a randomized controlled trial.

    PubMed

    Hajibagheri, Ali; Babaii, Atye; Adib-Hajbaghery, Mohsen

    2014-08-01

    Sleep disorders are common among patients hospitalized in coronary care unit (CCU). This study aimed to investigate the effect of Rosa damascene aromatherapy on sleep quality of patients hospitalized in CCU. In this randomized controlled trial, 60 patients who met the inclusion criteria were conveniently sampled and randomly allocated to the experimental and control groups. Patients in the control group received routine care. In the experimental group, patients received routine care and Rosa damascene aromatherapy for three subsequent nights. In the both groups the sleep quality was assessed using the Pittsburgh Sleep Quality Index. After the study, the mean scores of five domains of Pittsburg Sleep Quality Index as well as the mean of total score of the index in the experimental group were significantly lower than the control group. Rosa damascene aromatherapy can significantly improve the sleep quality of patients hospitalized in CCUs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Effect of massage therapy on pain, anxiety, relaxation, and tension after colorectal surgery: A randomized study.

    PubMed

    Dreyer, Nikol E; Cutshall, Susanne M; Huebner, Marianne; Foss, Diane M; Lovely, Jenna K; Bauer, Brent A; Cima, Robert R

    2015-08-01

    The purpose of this randomized controlled trial was to evaluate the effect of postoperative massage in patients undergoing abdominal colorectal surgery. One hundred twenty-seven patients were randomized to receive a 20-min massage (n = 61) or social visit and relaxation session (no massage; n = 66) on postoperative days 2 and 3. Vital signs and psychological well-being (pain, tension, anxiety, satisfaction with care, relaxation) were assessed before and after each intervention. The study results indicated that postoperative massage significantly improved the patients' perception of pain, tension, and anxiety, but overall satisfaction was unchanged. In conclusion, massage may be beneficial during postoperative recovery for patients undergoing abdominal colorectal surgery. Further studies are warranted to optimize timing and duration and to determine other benefits in this clinical setting.

  19. Random crystal field effect on the magnetic and hysteresis behaviors of a spin-1 cylindrical nanowire

    NASA Astrophysics Data System (ADS)

    Zaim, N.; Zaim, A.; Kerouad, M.

    2017-02-01

    In this work, the magnetic behavior of the cylindrical nanowire, consisting of a ferromagnetic core of spin-1 atoms surrounded by a ferromagnetic shell of spin-1 atoms is studied in the presence of a random crystal field interaction. Based on Metropolis algorithm, the Monte Carlo simulation has been used to investigate the effects of the concentration of the random crystal field p, the crystal field D and the shell exchange interaction Js on the phase diagrams and the hysteresis behavior of the system. Some characteristic behaviors have been found, such as the first and second-order phase transitions joined by tricritical point for appropriate values of the system parameters, triple and isolated critical points can be also found. Depending on the Hamiltonian parameters, single, double and para hysteresis regions are explicitly determined.

  20. Effects of Traditional Chinese Medicine Huangqi Injection (Radix astragali) on Random Skin Flap Survival in Rats.

    PubMed

    Cai, Leyi; Cao, Bin; Lin, Dingsheng

    2015-10-01

    Huangqi (Radix astragali) is a traditional Chinese drug, designed to "buqi," which means invigorating vital energy, widely used in clinical settings. We investigated the effect of Huangqi injection on the survival of random skin flaps. McFarlane flaps were established in 60 rats divided into two groups. Postoperative celiac injections were given to both groups for 7 days. Huangqi was injected into the test group, and saline was injected into controls. On day 7, tissues were stained with hematoxylin and eosin, immunohistochemically evaluated, and the expression levels of xanthine oxidase determined. The mean area of flap survival in the test group was significantly higher compared with the controls. Expression of vascular endothelial growth factor and superoxide dismutase, and microvessel development, were markedly increased in the test group, and the malondialdehyde level was reduced. Huangqi injection promotes random skin flap survival. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  1. Effect of side-stream smoking on random-pattern skin flap survival in rats.

    PubMed

    Gazzalle, Anajara; Teixeira, Lourenço Frigeri; Pellizzari, Alice Cardoso; Cocolichio, Fernanda; Zampieri, Juliana Tonietto; Rauber, Daniel; Pezzin, Luíse S; Zago, Vanessa D; Braga-Silva, Jefferson Luis

    2014-04-01

    The secondhand exposure to cigarette smoke is being considered evil, and damage caused by this passive exposure has been proven by several studies. To investigate the effects of sidestream smoke exposure on random-pattern skin flap survival, 20 female rats were separated into 2 groups: group A (n = 10) was exposed 6 weeks to the smoke from the burning cigarette (passive smoking) and group B (n = 10) was the control group. After 6 weeks of exposition, a dorsal McFarlane flap of 4 × 10 cm was performed in all rats. Two weeks after this procedure, the ratio of necrotic and total areas was calculated using computer programs. The median area of necrosis in group A was 29.5%, significantly higher than that in group B with 17.5% (P < 0.024). In conclusion, this study suggests increased risk of random-pattern skin flap necrosis after sidestream exposure to cigarette smoke.

  2. Stressed Cooper pairing in QCD at high isospin density: effective Lagrangian and random matrix theory

    NASA Astrophysics Data System (ADS)

    Kanazawa, Takuya; Wettig, Tilo

    2014-10-01

    We generalize QCD at asymptotically large isospin chemical potential to an arbitrary even number of flavors. We also allow for small quark chemical potentials, which stress the coincident Fermi surfaces of the paired quarks and lead to a sign problem in Monte Carlo simulations. We derive the corresponding low-energy effective theory in both p- and ɛ-expansion and quantify the severity of the sign problem. We construct the random matrix theory describing our physical situation and show that it can be mapped to a known random matrix theory at low baryon density so that new insights can be gained without additional calculations. In particular, we explain the Silver Blaze phenomenon at high isospin density. We also introduce stressed singular values of the Dirac operator and relate them to the pionic condensate. Finally we comment on extensions of our work to two-color QCD.

  3. Effects of random and deterministic discrete scale invariance on the critical behavior of the Potts model.

    PubMed

    Monceau, Pascal

    2012-12-01

    The effects of disorder on the critical behavior of the q-state Potts model in noninteger dimensions are studied by comparison of deterministic and random fractals sharing the same dimensions in the framework of a discrete scale invariance. We carried out intensive Monte Carlo simulations. In the case of a fractal dimension slightly smaller than two d(f) ~/= 1.974636, we give evidence that the disorder structured by discrete scale invariance does not change the first order transition associated with the deterministic case when q = 7. Furthermore the study of the high value q = 14 shows that the transition is a second order one both for deterministic and random scale invariance, but that their behavior belongs to different university classes.

  4. A randomized effectiveness trial of a sex education program for minority youth in Miami, Florida.

    PubMed

    Sherr, Michael E; Pooler, David; Stamey, James; Jones, Johnny; Dyer, Preston

    2013-01-01

    Through this study the authors assessed the outcomes of a randomized effectiveness trial of Project U-Turn, a comprehensive sex education program for at-risk youth in Miami, Florida. Data collection occurred at pretest, three month, and six month follow-ups with a sample of teenagers randomly selected and assigned to treatment (n = 549) and control (n = 424) groups. Results from logistical and generalized multilevel modeling indicated the program did not contribute to teen responses at three or six month follow-ups. Other variables, however, had some influence on predicting teen responses to questions about their current and future sexual activity. Gender, use of alcohol, and participation in religious services predicted responses from teens at pretest and at three and six month follow-ups. Discussion of the findings, as well as implications for evidence-based social work with teens conclude the article.

  5. Finite size effects in the averaged eigenvalue density of Wigner random-sign real symmetric matrices

    NASA Astrophysics Data System (ADS)

    Dhesi, G. S.; Ausloos, M.

    2016-06-01

    Nowadays, strict finite size effects must be taken into account in condensed matter problems when treated through models based on lattices or graphs. On the other hand, the cases of directed bonds or links are known to be highly relevant in topics ranging from ferroelectrics to quotation networks. Combining these two points leads us to examine finite size random matrices. To obtain basic materials properties, the Green's function associated with the matrix has to be calculated. To obtain the first finite size correction, a perturbative scheme is hereby developed within the framework of the replica method. The averaged eigenvalue spectrum and the corresponding Green's function of Wigner random sign real symmetric N ×N matrices to order 1 /N are finally obtained analytically. Related simulation results are also presented. The agreement is excellent between the analytical formulas and finite size matrix numerical diagonalization results, confirming the correctness of the first-order finite size expression.

  6. Static and dynamic optical properties of La1-xSrxFeO3-δ: The effects of A-site and oxygen stoichiometry

    SciTech Connect

    Sergey Y. Smolin; Sfeir, Matthew Y.; Scafetta, Mark D.; Choquette, Amber K.; Baxter, Jason B.; May, Steven J.

    2015-12-09

    Perovskite oxides are a promising material class for photovoltaic and photocatalytic applications due to their visible band gaps, nanosecond recombination lifetimes, and great chemical diversity. However, there is limited understanding of the link between composition and static and dynamic optical properties, despite the critical role these properties play in the design of light-harvesting devices. To clarify these relationships, we systemically studied the optoelectronic properties in La1-xSrxFeO3-δ epitaxial films, uncovering the effects of A-site cation substitution and oxygen stoichiometry. Variable-angle spectroscopic ellipsometry was used to measure static optical properties, revealing a linear increase in absorption coefficient at 1.25 eV and a red-shifting of the optical absorption edge with increasing Sr fraction. The absorption spectra can be similarly tuned through the introduction of oxygen vacancies, indicating the critical role that nominal Fe valence plays in optical absorption. Dynamic optoelectronic properties were studied with ultrafast transient reflectance spectroscopy, revealing similar nanosecond photoexcited carrier lifetimes for oxygen deficient and stoichiometric films with the same nominal Fe valence. Furthermore, these results demonstrate that while the static optical absorption is strongly dependent on nominal Fe valence tuned through cation or anion stoichiometry, oxygen vacancies do not appear to play a significantly detrimental role in the recombination kinetics.

  7. A-site ordered quadruple perovskite oxides

    NASA Astrophysics Data System (ADS)

    Youwen, Long

    2016-07-01

    The A-site ordered perovskite oxides with chemical formula display many intriguing physical properties due to the introduction of transition metals at both A‧ and B sites. Here, research on the recently discovered intermetallic charge transfer occurring between A‧-site Cu and B-site Fe ions in LaCu3Fe4O12 and its analogues is reviewed, along with work on the magnetoelectric multiferroicity observed in LaMn3Cr4O12 with cubic perovskite structure. The Cu-Fe intermetallic charge transfer leads to a first-order isostructural phase transition accompanied by drastic variations in magnetism and electrical transport properties. The LaMn3Cr4O12 is a novel spin-driven multiferroic system with strong magnetoelectric coupling effects. The compound is the first example of cubic perovskite multiferroics to be found. It opens up a new arena for studying unexpected multiferroic mechanisms. Project supported by the National Basic Research Program of China (Grant No. 2014CB921500), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB07030300), and the National Natural Science Foundation of China (Grant No. 11574378).

  8. Aerobic exercise effects upon cognition in Mild Cognitive Impairment: A systematic review of randomized controlled trials.

    PubMed

    Cammisuli, D M; Innocenti, A; Franzoni, F; Pruneti, C

    2017-07-01

    Several studies have shown that physical activity has positive effects on cognition in healthy older adults without cognitive complains but lesser is known about the effectiveness of aerobic exercise in patients suffering from Mild Cognitive Impairment (MCI). The aim of the present study was to systematically review the evidence from randomized controlled trials (RCTs) about the effects of aerobic exercise upon cognition in MCI patients. To this end, PubMed, Cochrane and Web of Science databases were analytically searched for RCTs including aerobic exercise interventions for MCI patients. There is evidence that aerobic exercise improves cognition in MCI patients. Overall research reported moderate effects for global cognition, logical memory, inhibitory control and divided attention. Due to methodological limitations of the investigated studies, findings should be interpreted with caution. Standardized training protocols, larger scale interventions and follow-ups may also provide better insight into the preventive effects of aerobic exercise on cognitive deterioration in MCI and its conversion into dementia.

  9. Probiotics' preventive effect on pediatric food allergy: a meta-analysis of randomized controlled trials.

    PubMed

    Kong, Xiang-yi; Yang, Yi; Guan, Jian; Wang, Ren-zhi

    2014-09-01

    To investigate the preventive effect of probiotics on pediatric food allergy. From MEDLINE bibliographical database, we searched and reviewed all randomized controlled trials on the preventive effects of probiotics on pediatric food allergies up to September 2013 and excluded the studies that do not meet inclusion criteria and extracted the data. Meta-analysis for the results of homogenous studies was performed using RevMan 5.0 and the co-effect was pooled by using fixed-effects model of relative risk (RR) ratios. Ten trials published between 2007 and 2012 including 2701 cases were included. Meta-analysis based on included data showed that the preventive effect of prenatal and postnatal probiotic supplementation on food allergies was not significant with the RR=0.88 (95% CI: 0.76-1.03). Present evidences cannot show in unequivocal terms that prenatal and postnatal probiotic supplementation will prevent food allergic diseases.

  10. The Effect of Random Error on Diagnostic Accuracy Illustrated with the Anthropometric Diagnosis of Malnutrition

    PubMed Central

    2016-01-01

    Background It is often thought that random measurement error has a minor effect upon the results of an epidemiological survey. Theoretically, errors of measurement should always increase the spread of a distribution. Defining an illness by having a measurement outside an established healthy range will lead to an inflated prevalence of that condition if there are measurement errors. Methods and results A Monte Carlo simulation was conducted of anthropometric assessment of children with malnutrition. Random errors of increasing magnitude were imposed upon the populations and showed that there was an increase in the standard deviation with each of the errors that became exponentially greater with the magnitude of the error. The potential magnitude of the resulting error of reported prevalence of malnutrition were compared with published international data and found to be of sufficient magnitude to make a number of surveys and the numerous reports and analyses that used these data unreliable. Conclusions The effect of random error in public health surveys and the data upon which diagnostic cut-off points are derived to define “health” has been underestimated. Even quite modest random errors can more than double the reported prevalence of conditions such as malnutrition. Increasing sample size does not address this problem, and may even result in less accurate estimates. More attention needs to be paid to the selection, calibration and maintenance of instruments, measurer selection, training & supervision, routine estimation of the likely magnitude of errors using standardization tests, use of statistical likelihood of error to exclude data from analysis and full reporting of these procedures in order to judge the reliability of survey reports. PMID:28030627

  11. Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement.

    PubMed

    Borges, Alexandre L S; Münchow, Eliseu A; de Oliveira Souza, Ana Carolina; Yoshida, Takamitsu; Vallittu, Pekka K; Bottino, Marco C

    2015-08-01

    The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite. Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20×2×2 mm(3)) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey׳s test (α=5%). Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes׳ presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5 wt%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. A practical guide and power analysis for GLMMs: detecting among treatment variation in random effects

    PubMed Central

    Bolker, Ben M.; McCoy, Michael W.

    2015-01-01

    In ecology and evolution generalized linear mixed models (GLMMs) are becoming increasingly used to test for differences in variation by treatment at multiple hierarchical levels. Yet, the specific sampling schemes that optimize the power of an experiment to detect differences in random effects by treatment/group remain unknown. In this paper we develop a blueprint for conducting power analyses for GLMMs focusing on detecting differences in variance by treatment. We present parameterization and power analyses for random-intercepts and random-slopes GLMMs because of their generality as focal parameters for most applications and because of their immediate applicability to emerging questions in the field of behavioral ecology. We focus on the extreme case of hierarchically structured binomial data, though the framework presented here generalizes easily to any error distribution model. First, we determine the optimal ratio of individuals to repeated measures within individuals that maximizes power to detect differences by treatment in among-individual variation in intercept, among-individual variation in slope, and within-individual variation in intercept. Second, we explore how power to detect differences in target variance parameters is affected by total variation. Our results indicate heterogeneity in power across ratios of individuals to repeated measures with an optimal ratio determined by both the target variance parameter and total sample size. Additionally, power to detect each variance parameter was low overall (in most cases >1,000 total observations per treatment needed to achieve 80% power) and decreased with increasing variance in non-target random effects. With growing interest in variance as the parameter of inquiry, these power analyses provide a crucial component for designing experiments focused on detecting differences in variance. We hope to inspire novel experimental designs in ecology and evolution investigating the causes and implications of

  13. Effects of Testosterone Replacement on Electrocardiographic Parameters in Men: Findings From Two Randomized Trials.

    PubMed

    Gagliano-Jucá, Thiago; Içli, Tevhide Betül; Pencina, Karol M; Li, Zhuoying; Tapper, John; Huang, Grace; Travison, Thomas G; Tsitouras, Panayiotis; Harman, S Mitchell; Storer, Thomas W; Bhasin, Shalender; Basaria, Shehzad

    2017-05-01

    Endogenous testosterone levels have been negatively associated with QTc interval in small case series; the effects of testosterone therapy on electrocardiographic parameters have not been evaluated in randomized trials. To evaluate the effects of testosterone replacement on corrected QT interval (QTcF) in two randomized controlled trials. Men with pre- and postrandomization electrocardiograms (ECGs) from the Testosterone and Pain (TAP) and the Testosterone Effects on Atherosclerosis in Aging Men (TEAAM) Trials. Participants were randomized to either placebo or testosterone gel for 14 weeks (TAP) or 36 months (TEAAM). ECGs were performed at baseline and at the end of interventions in both trials; in the TEAAM trial ECGs were also obtained at 12 and 24 months. Difference in change in the QTcF between testosterone and placebo groups was assessed in each trial. Association of changes in testosterone levels with changes in QTcF was analyzed in men assigned to the testosterone group of each trial. Mean total testosterone levels increased in the testosterone group of both trials. In the TAP trial, there was a nonsignificant reduction in mean QTcF in the testosterone group compared with placebo (effect size = -4.72 ms; P = 0.228) and the changes in QTcF were negatively associated to changes in circulating testosterone (P = 0.036). In the TEAAM trial, testosterone attenuated the age-related increase in QTcF seen in the placebo group (effect size= -6.30 ms; P < 0.001). Testosterone replacement attenuated the age-related increase in QTcF duration in men. The clinical implications of these findings require further investigation.

  14. Effects of music on immunity and physiological responses in healthcare workers: a randomized controlled trial.

    PubMed

    Lai, Hui-Ling; Liao, Kuang-Wen; Huang, Chiung-Yu; Chen, Pin-Wen; Peng, Tai-Chu

    2013-04-01

    Research-based evidence supports the effectiveness of soothing music in improving stress-related psycho-physiological indices in a clinical setting. However, there is currently insufficient scientific knowledge of the effects of music on immune markers of stress in humans. Therefore, the aims of the study were to compare the effects of music and quiet rest on the levels of interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), interleukin-10 (IL-10), heart rate and mean arterial pressure among healthcare workers. By using a randomized controlled trial design, 60 nurses were randomly assigned to the stimulating or sedating music or rest groups for 30 min. Participants' psychoneuroimmunological parameters were measured using enzyme-linked immunosorbent assays. General estimating equation was used to analyse data. Results revealed that IL-6, TNF-α and IL-10 were not detectable in this population. No significance differences in heart rate were found among the three groups. However, the stimulating music group had significantly higher mean arterial pressure levels than the sedating music group but no differences between the quiet rest group and the sedating music group. Music with different tempi had little effect on mean arterial pressure. Any effect of music on immune markers of stress requires further research. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Sequential change detection and monitoring of temporal trends in random-effects meta-analysis.

    PubMed

    Dogo, Samson Henry; Clark, Allan; Kulinskaya, Elena

    2017-06-01

    Temporal changes in magnitude of effect sizes reported in many areas of research are a threat to the credibility of the results and conclusions of meta-analysis. Numerous sequential methods for meta-analysis have been proposed to detect changes and monitor trends in effect sizes so that meta-analysis can be updated when necessary and interpreted based on the time it was conducted. The difficulties of sequential meta-analysis under the random-effects model are caused by dependencies in increments introduced by the estimation of the heterogeneity parameter τ(2) . In this paper, we propose the use of a retrospective cumulative sum (CUSUM)-type test with bootstrap critical values. This method allows retrospective analysis of the past trajectory of cumulative effects in random-effects meta-analysis and its visualization on a chart similar to CUSUM chart. Simulation results show that the new method demonstrates good control of Type I error regardless of the number or size of the studies and the amount of heterogeneity. Application of the new method is illustrated on two examples of medical meta-analyses. © 2016 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd. © 2016 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd.

  16. Spatial panel data models of aquaculture production in West Sumatra province with random-effects

    NASA Astrophysics Data System (ADS)

    Sartika, Wimi; Susetyo, Budi; Syafitri, Utami Dyah

    2017-03-01

    Spatial Panel Regression is a statistical model that used to analyze the effect of several independent variables on the dependent variable based on using panel data and take the spatial effect into account. There are two approaches on predicting spatial panel data, Fixed Effect Spatial Autoregressive (SAR-FE) and Random Effect Spatial Autoregressive (SAR-RE). SAR-FE has the assumption that the intercept has vary acrros spatial unit, while the SAR-RE's assumption is the interception is on residual model and it only has a general intercept. The purpose of this study is to modeling the production of West Sumatra fishery using Spatial Panel Regression. The model uses secondary data which is published by "Badan Pusat Statistik" on the results of aquaculture production in West Sumatra. The test results shown that the level of West Sumatra 2004-2012 aquaculture production was precisely modeled by the approach of Spatial Autoregressive Random Effect. From SAR-RE model, the most influence factors on aquaculture production in West Sumatra province in 2004-2012 was the number of motor boats, the area of fish seeds, fish seed production, and the number of fishermen public waters.

  17. Additive effects of neurofeedback on the treatment of ADHD: A randomized controlled study.

    PubMed

    Lee, Eun-Jeong; Jung, Chul-Ho

    2017-02-01

    Neurofeedback (NF) has been identified as a "possibly efficacious" treatment in current evidence-based reviews; therefore, more research is needed to determine its effects. The current study examined the potential additive effect of NF for children diagnosed with ADHD beginning a medication trial first. Thirty-six children (6-12 years) with a DSM-IV-TR diagnosis of ADHD were randomly assigned to an NF with medication (NF condition) or a medication only condition. Children in the NF group attended 20 twice-weekly sessions. Outcome measures included individual cognitive performance scores (ADS, K-WISC-III), ADHD rating scores completed by their parents (ARS, CRS) and brainwave indices of left and right hemispheres before and after NF treatment. Significant additive treatment effect in any of the symptom variables was found and a reduction of theta waves in both the right and left hemispheres was recorded in NF condition participants. However our randomized controlled study could not demonstrate superior effects of combined NF on intelligent functioning compared to the medication treatment only. This study suggested any possible evidence of positive and additive treatment effects of NF on brainwaves and ADHD symptomatology.

  18. Hierarchical Bayesian modeling of random and residual variance-covariance matrices in bivariate mixed effects models.

    PubMed

    Bello, Nora M; Steibel, Juan P; Tempelman, Robert J

    2010-06-01

    Bivariate mixed effects models are often used to jointly infer upon covariance matrices for both random effects (u) and residuals (e) between two different phenotypes in order to investigate the architecture of their relationship. However, these (co)variances themselves may additionally depend upon covariates as well as additional sets of exchangeable random effects that facilitate borrowing of strength across a large number of clusters. We propose a hierarchical Bayesian extension of the classical bivariate mixed effects model by embedding additional levels of mixed effects modeling of reparameterizations of u-level and e-level (co)variances between two traits. These parameters are based upon a recently popularized square-root-free Cholesky decomposition and are readily interpretable, each conveniently facilitating a generalized linear model characterization. Using Markov Chain Monte Carlo methods, we validate our model based on a simulation study and apply it to a joint analysis of milk yield and calving interval phenotypes in Michigan dairy cows. This analysis indicates that the e-level relationship between the two traits is highly heterogeneous across herds and depends upon systematic herd management factors.

  19. 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

  20. The Effect of Interference on Temporal Order Memory for Random and Fixed Sequences in Nondemented Older Adults

    ERIC Educational Resources Information Center

    Tolentino, Jerlyn C.; Pirogovsky, Eva; Luu, Trinh; Toner, Chelsea K.; Gilbert, Paul E.

    2012-01-01

    Two experiments tested the effect of temporal interference on order memory for fixed and random sequences in young adults and nondemented older adults. The results demonstrate that temporal order memory for fixed and random sequences is impaired in nondemented older adults, particularly when temporal interference is high. However, temporal order…

  1. The Ecological Effects of Universal and Selective Violence Prevention Programs for Middle School Students: A Randomized Trial

    ERIC Educational Resources Information Center

    Simon, Thomas R.; Ikeda, Robin M.; Smith, Emilie Phillips; Reese, Le'Roy E.; Rabiner, David L.; Miller, Shari; Winn, Donna-Marie; Dodge, Kenneth A.; Asher, Steven R.; Horne, Arthur M.; Orpinas, Pamela; Martin, Roy; Quinn, William H.; Tolan, Patrick H.; Gorman-Smith, Deborah; Henry, David B.; Gay, Franklin N.; Schoeny, Michael; Farrell, Albert D.; Meyer, Aleta L.; Sullivan, Terri N.; Allison, Kevin W.

    2009-01-01

    This study reports the findings of a multisite randomized trial evaluating the separate and combined effects of 2 school-based approaches to reduce violence among early adolescents. A total of 37 schools at 4 sites were randomized to 4 conditions: (1) a universal intervention that involved implementing a student curriculum and teacher training…

  2. Cognitive-Behavioral Treatment for Panic Disorder with Agoraphobia: A Randomized, Controlled Trial and Cost-Effectiveness Analysis

    ERIC Educational Resources Information Center

    Roberge, Pasquale; Marchand, Andre; Reinharz, Daniel; Savard, Pierre

    2008-01-01

    A randomized, controlled trial was conducted to examine the cost-effectiveness of cognitive-behavioral treatment (CBT) for panic disorder with agoraphobia. A total of 100 participants were randomly assigned to standard (n = 33), group (n = 35), and brief (n = 32) treatment conditions. Results show significant clinical and statistical improvement…

  3. Effects of Cognitive Enhancement Therapy on Employment Outcomes in Early Schizophrenia: Results from a 2-Year Randomized Trial

    ERIC Educational Resources Information Center

    Eack, Shaun M.; Hogarty, Gerard E.; Greenwald, Deborah P.; Hogarty, Susan S.; Keshavan, Matcheri S.

    2011-01-01

    Objective: To examine the effects of psychosocial cognitive rehabilitation on employment outcomes in a randomized controlled trial for individuals with early course schizophrenia. Method: Early course schizophrenia outpatients (N = 58) were randomly assigned to cognitive enhancement therapy (CET) or an enriched supportive therapy (EST) control and…

  4. Effects of Cognitive Enhancement Therapy on Employment Outcomes in Early Schizophrenia: Results from a 2-Year Randomized Trial

    ERIC Educational Resources Information Center

    Eack, Shaun M.; Hogarty, Gerard E.; Greenwald, Deborah P.; Hogarty, Susan S.; Keshavan, Matcheri S.

    2011-01-01

    Objective: To examine the effects of psychosocial cognitive rehabilitation on employment outcomes in a randomized controlled trial for individuals with early course schizophrenia. Method: Early course schizophrenia outpatients (N = 58) were randomly assigned to cognitive enhancement therapy (CET) or an enriched supportive therapy (EST) control and…

  5. The Effect of Interference on Temporal Order Memory for Random and Fixed Sequences in Nondemented Older Adults

    ERIC Educational Resources Information Center

    Tolentino, Jerlyn C.; Pirogovsky, Eva; Luu, Trinh; Toner, Chelsea K.; Gilbert, Paul E.

    2012-01-01

    Two experiments tested the effect of temporal interference on order memory for fixed and random sequences in young adults and nondemented older adults. The results demonstrate that temporal order memory for fixed and random sequences is impaired in nondemented older adults, particularly when temporal interference is high. However, temporal order…

  6. The Effects of School Gardens on Children's Science Knowledge: A Randomized Controlled Trial of Low-Income Elementary Schools

    ERIC Educational Resources Information Center

    Wells, Nancy M.; Myers, Beth M.; Todd, Lauren E.; Barale, Karen; Gaolach, Brad; Ferenz, Gretchen; Aitken, Martha; Henderson, Charles R.; Tse, Caroline; Pattison, Karen Ostlie; Taylor, Cayla; Connerly, Laura; Carson, Janet B.; Gensemer, Alexandra Z.; Franz, Nancy K.; Falk, Elizabeth

    2015-01-01

    This randomized controlled trial or "true experiment" examines the effects of a school garden intervention on the science knowledge of elementary school children. Schools were randomly assigned to a group that received the garden intervention (n?=?25) or to a waitlist control group that received the garden intervention at the end of the…

  7. The Ecological Effects of Universal and Selective Violence Prevention Programs for Middle School Students: A Randomized Trial

    ERIC Educational Resources Information Center

    Simon, Thomas R.; Ikeda, Robin M.; Smith, Emilie Phillips; Reese, Le'Roy E.; Rabiner, David L.; Miller, Shari; Winn, Donna-Marie; Dodge, Kenneth A.; Asher, Steven R.; Horne, Arthur M.; Orpinas, Pamela; Martin, Roy; Quinn, William H.; Tolan, Patrick H.; Gorman-Smith, Deborah; Henry, David B.; Gay, Franklin N.; Schoeny, Michael; Farrell, Albert D.; Meyer, Aleta L.; Sullivan, Terri N.; Allison, Kevin W.

    2009-01-01

    This study reports the findings of a multisite randomized trial evaluating the separate and combined effects of 2 school-based approaches to reduce violence among early adolescents. A total of 37 schools at 4 sites were randomized to 4 conditions: (1) a universal intervention that involved implementing a student curriculum and teacher training…

  8. Cognitive-Behavioral Treatment for Panic Disorder with Agoraphobia: A Randomized, Controlled Trial and Cost-Effectiveness Analysis

    ERIC Educational Resources Information Center

    Roberge, Pasquale; Marchand, Andre; Reinharz, Daniel; Savard, Pierre

    2008-01-01

    A randomized, controlled trial was conducted to examine the cost-effectiveness of cognitive-behavioral treatment (CBT) for panic disorder with agoraphobia. A total of 100 participants were randomly assigned to standard (n = 33), group (n = 35), and brief (n = 32) treatment conditions. Results show significant clinical and statistical improvement…

  9. The Effects of School Gardens on Children's Science Knowledge: A Randomized Controlled Trial of Low-Income Elementary Schools

    ERIC Educational Resources Information Center

    Wells, Nancy M.; Myers, Beth M.; Todd, Lauren E.; Barale, Karen; Gaolach, Brad; Ferenz, Gretchen; Aitken, Martha; Henderson, Charles R.; Tse, Caroline; Pattison, Karen Ostlie; Taylor, Cayla; Connerly, Laura; Carson, Janet B.; Gensemer, Alexandra Z.; Franz, Nancy K.; Falk, Elizabeth

    2015-01-01

    This randomized controlled trial or "true experiment" examines the effects of a school garden intervention on the science knowledge of elementary school children. Schools were randomly assigned to a group that received the garden intervention (n?=?25) or to a waitlist control group that received the garden intervention at the end of the…

  10. Randomized Controlled Trial in Clinical Settings to Evaluate Effectiveness of Coping Skills Education Used with Progressive Tinnitus Management

    ERIC Educational Resources Information Center

    Henry, James A.; Thielman, Emily J.; Zaugg, Tara L.; Kaelin, Christine; Schmidt, Caroline J.; Griest, Susan; McMillan, Garnett P.; Myers, Paula; Rivera, Izel; Baldwin, Robert; Carlson, Kathleen

    2017-01-01

    Purpose: This randomized controlled trial evaluated, within clinical settings, the effectiveness of coping skills education that is provided with progressive tinnitus management (PTM). Method: At 2 Veterans Affairs medical centers, N = 300 veterans were randomized to either PTM intervention or 6-month wait-list control. The PTM intervention…

  11. Finite-element method for calculation of the effective permittivity of random inhomogeneous media

    NASA Astrophysics Data System (ADS)

    Myroshnychenko, Viktor; Brosseau, Christian

    2005-01-01

    The challenge of designing new solid-state materials from calculations performed with the help of computers applied to models of spatial randomness has attracted an increasing amount of interest in recent years. In particular, dispersions of particles in a host matrix are scientifically and technologically important for a variety of reasons. Herein, we report our development of an efficient computer code to calculate the effective (bulk) permittivity of two-phase disordered composite media consisting of hard circular disks made of a lossless dielectric (permittivity ɛ2 ) randomly placed in a plane made of a lossless homogeneous dielectric (permittivity ɛ1 ) at different surface fractions. Specifically, the method is based on (i) a finite-element description of composites in which both the host and the randomly distributed inclusions are isotropic phases, and (ii) an ordinary Monte Carlo sampling. Periodic boundary conditions are employed throughout the simulation and various numbers of disks have been considered in the calculations. From this systematic study, we show how the number of Monte Carlo steps needed to achieve equilibrated distributions of disks increases monotonically with the surface fraction. Furthermore, a detailed study is made of the dependence of the results on a minimum separation distance between disks. Numerical examples are presented to connect the macroscopic property such as the effective permittivity to microstructural characteristics such as the mean coordination number and radial distribution function. In addition, several approximate effective medium theories, exact bounds, exact results for two-dimensional regular arrays, and the exact dilute limit are used to test and validate the finite-element algorithm. Numerical results indicate that the fourth-order bounds provide an excellent estimate of the effective permittivity for a wide range of surface fractions, in accordance with the fact that the bounds become progressively narrower as

  12. Acute anti-inflammatory effects of inhaled budesonide in asthma: a randomized controlled trial.

    PubMed

    Gibson, P G; Saltos, N; Fakes, K

    2001-01-01

    Corticosteroids can have acute effects on airway function and methacholine airway responsiveness in asthma as early as 6 h after dosing, suggesting there may be an acute anti-inflammatory effect of inhaled corticosteroid in asthma. This study aimed to determine the effects of a single dose of inhaled budesonide on sputum eosinophils and mast cells in adults with asthma, and to examine whether the mechanism of clearance of eosinophils was by apoptosis. A randomized, double-blind, placebo-controlled, crossover study was conducted. At the screening visit, adults with stable asthma (n = 41) ceased inhaled corticosteroid therapy for 4 d and those with significant sputum eosinophilia (> or = 7%) were randomized (n = 26) to a single dose of budesonide 2,400 microg or placebo via Turbuhaler, on two separate study days. Symptoms and lung function were followed for 6 h, then sputum was induced and airway responsiveness to hypertonic saline determined. Sputum eosinophils (mean, SE) were significantly lower 6 h after budesonide (25%, 4.5), compared with placebo (37%, 6.2, p < 0.05). There was a 2.2-fold (95% CI 1.45 to 3.33) improvement in airway responsiveness with budesonide. No significant difference was seen on mast cells, apoptotic eosinophils, symptoms, or lung function. In conclusion, a single dose of inhaled corticosteroids has beneficial effects on airway inflammation and airway hyperresponsiveness as early as 6 h after dosing. This may be clinically useful as therapy during mild exacerbations of asthma.

  13. Bayesian nonparametric regression analysis of data with random effects covariates from longitudinal measurements.

    PubMed

    Ryu, Duchwan; Li, Erning; Mallick, Bani K

    2011-06-01

    We consider nonparametric regression analysis in a generalized linear model (GLM) framework for data with covariates that are the subject-specific random effects of longitudinal measurements. The usual assumption that the effects of the longitudinal covariate processes are linear in the GLM may be unrealistic and if this happens it can cast doubt on the inference of observed covariate effects. Allowing the regression functions to be unknown, we propose to apply Bayesian nonparametric methods including cubic smoothing splines or P-splines for the possible nonlinearity and use an additive model in this complex setting. To improve computational efficiency, we propose the use of data-augmentation schemes. The approach allows flexible covariance structures for the random effects and within-subject measurement errors of the longitudinal processes. The posterior model space is explored through a Markov chain Monte Carlo (MCMC) sampler. The proposed methods are illustrated and compared to other approaches, the "naive" approach and the regression calibration, via simulations and by an application that investigates the relationship between obesity in adulthood and childhood growth curves.

  14. The effectiveness of music in relieving pain in cancer patients: a randomized controlled trial.

    PubMed

    Huang, Shih-Tzu; Good, Marion; Zauszniewski, Jaclene A

    2010-11-01

    To examine effects of sedative music on cancer pain. A randomized controlled trial. Two large medical centers in Kaoshiung City, in southern Taiwan. 126 hospitalized persons with cancer pain. Participants were randomly assigned to an experimental (n=62) or a control group (n=64), with computerized minimization, stratifying on gender, pain, and hospital unit. Music choices included folk songs, Buddhist hymns (Taiwanese music), plus harp, and piano (American). The experimental group listened to music for 30 min; the control group rested in bed. Sensation and distress of pain were rated on 100mm VAS before and after the 30-min test. Using MANCOVA, there was significantly less posttest pain in the music versus the control group, p<.001. Effect sizes were large, Cohen's d=.64, sensation, d=.70, distress, indicating that music was very helpful for pain. Thirty minutes of music provided 50% relief in 42% of the music group compared to 8% of the controls. The number needed to treat (NNT) to find one with 50% sensation relief was three patients. More patients chose Taiwanese music (71%) than American music (29%), but both were liked and effective. Offering a choice of familiar, culturally appropriate music was a key element of the intervention. Findings extend the Good and Moore theory (1996) to cancer pain. Soft music was safe, effective, and liked by participants. It provided greater relief of cancer pain than analgesics alone. Thus nurses should offer calming, familiar music to supplement analgesic medication for persons with cancer pain. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Random-effects meta-analysis: the number of studies matters.

    PubMed

    Guolo, Annamaria; Varin, Cristiano

    2017-06-01

    This paper investigates the impact of the number of studies on meta-analysis and meta-regression within the random-effects model framework. It is frequently neglected that inference in random-effects models requires a substantial number of studies included in meta-analysis to guarantee reliable conclusions. Several authors warn about the risk of inaccurate results of the traditional DerSimonian and Laird approach especially in the common case of meta-analysis involving a limited number of studies. This paper presents a selection of likelihood and non-likelihood methods for inference in meta-analysis proposed to overcome the limitations of the DerSimonian and Laird procedure, with a focus on the effect of the number of studies. The applicability and the performance of the methods are investigated in terms of Type I error rates and empirical power to detect effects, according to scenarios of practical interest. Simulation studies and applications to real meta-analyses highlight that it is not possible to identify an approach uniformly superior to alternatives. The overall recommendation is to avoid the DerSimonian and Laird method when the number of meta-analysis studies is modest and prefer a more comprehensive procedure that compares alternative inferential approaches. R code for meta-analysis according to all of the inferential methods examined in the paper is provided.

  16. The effect of acupuncture on stroke recovery: study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Stroke is one of the leading causes of death and disability in China. Current treatments for stroke are limited and achieve no optimal effect. Acupuncture is widely used in the treatment of stroke and in improving the quality of life for patients in China. In most previous clinical studies, the effects of acupuncture have been diverse, and few well-designed randomized controlled trials have been conducted to investigate the long-term effect of acupuncture on acute stroke recovery. Method Three hundred and twenty eight subjects with acute cerebral apoplexy will be recruited. The patients will be randomized into two different groups: the intervention group will receive acupuncture treatment together with Western standard treatment for 2 weeks plus the secondary prevention treatment for 22 weeks; the control group will receive only the Western standard treatment for 2 weeks and the secondary prevention treatment for 22 weeks. The primary outcome measures are Barthel Index and the Stroke-Specific Quality Of Life. The secondary outcome measures are the National Institutes of Health Stroke Scale and Modified Rankin Scale. All assessments will be conducted at the baseline and at weeks 4, 12 and 24 of follow-up. Discussion This study will evaluate the effects of acupuncture on the long-term recovery of acute stroke and on improving the quality of life of the patients. The results of this study will help establish optimal integrated therapeutic strategies for patients with stroke. Trial registration Current Controlled Trials ISRCTN29932220 PMID:23145765

  17. Is EEG-biofeedback an effective treatment in autism spectrum disorders? A randomized controlled trial.

    PubMed

    Kouijzer, Mirjam E J; van Schie, Hein T; Gerrits, Berrie J L; Buitelaar, Jan K; de Moor, Jan M H

    2013-03-01

    EEG-biofeedback has been reported to reduce symptoms of autism spectrum disorders (ASD) in several studies. However, these studies did not control for nonspecific effects of EEG-biofeedback and did not distinguish between participants who succeeded in influencing their own EEG activity and participants who did not. To overcome these methodological shortcomings, this study evaluated the effects of EEG-biofeedback in ASD in a randomized pretest-posttest control group design with blinded active comparator and six months follow-up. Thirty-eight participants were randomly allocated to the EEG-biofeedback, skin conductance (SC)-biofeedback or waiting list group. EEG- and SC-biofeedback sessions were similar and participants were blinded to the type of feedback they received. Assessments pre-treatment, post-treatment, and after 6 months included parent ratings of symptoms of ASD, executive function tasks, and 19-channel EEG recordings. Fifty-four percent of the participants significantly reduced delta and/or theta power during EEG-biofeedback sessions and were identified as EEG-regulators. In these EEG-regulators, no statistically significant reductions of symptoms of ASD were observed, but they showed significant improvement in cognitive flexibility as compared to participants who managed to regulate SC. EEG-biofeedback seems to be an applicable tool to regulate EEG activity and has specific effects on cognitive flexibility, but it did not result in significant reductions in symptoms of ASD. An important finding was that no nonspecific effects of EEG-biofeedback were demonstrated.

  18. Effectiveness and moderators of the preventive intervention kids in divorce situations: A randomized controlled trial.

    PubMed

    Pelleboer-Gunnink, Hannah A; Van der Valk, Inge E; Branje, Susan J T; Van Doorn, Muriel D; Deković, Maja

    2015-10-01

    Children of divorced parents have an increased risk of a variety of problems in comparison to children from intact families. Therefore, several intervention programs have been developed directed at children of divorced parents. Yet, empirical data on the effectiveness of these interventions are limited. This study evaluated the school-based, child-directed prevention program Kids In Divorce Situations (KIDS) using a randomized controlled trial. The sample consisted of 156 children randomly assigned at the school level into an experimental (80 children) and control condition (76 children). In addition, 131 mothers and 76 fathers participated in the study. Four assessments took place: a pretest, a posttest, and two follow-up assessments conducted 6 months and 1 year after finishing KIDS. Latent growth analyses demonstrated that the intervention significantly reduced child-reported emotional problems and enhanced child-reported communication with the father and mother-reported communication with the child. The effect sizes ranged from .30-.63. Few moderation effects of gender, time since divorce, or perceived parental conflict on the intervention effects were found. After parental divorce, a limited school-based intervention for children can be efficacious in promoting children's emotional well-being and parent-child communication.

  19. Technology diffusion in hospitals: a log odds random effects regression model.

    PubMed

    Blank, Jos L T; Valdmanis, Vivian G

    2015-01-01

    This study identifies the factors that affect the diffusion of hospital innovations. We apply a log odds random effects regression model on hospital micro data. We introduce the concept of clustering innovations and the application of a log odds random effects regression model to describe the diffusion of technologies. We distinguish a number of determinants, such as service, physician, and environmental, financial and organizational characteristics of the 60 Dutch hospitals in our sample. On the basis of this data set on Dutch general hospitals over the period 1995-2002, we conclude that there is a relation between a number of determinants and the diffusion of innovations underlining conclusions from earlier research. Positive effects were found on the basis of the size of the hospitals, competition and a hospital's commitment to innovation. It appears that if a policy is developed to further diffuse innovations, the external effects of demand and market competition need to be examined, which would de facto lead to an efficient use of technology. For the individual hospital, instituting an innovations office appears to be the most prudent course of action. © 2013 The Authors. International Journal of Health Planning and Management published by John Wiley & Sons, Ltd.

  20. Differential Peer Effects, Student Achievement, and Student Absenteeism: Evidence From a Large-Scale Randomized Experiment.

    PubMed

    Eren, Ozkan

    2017-04-01

    Using data from a well-executed randomized experiment, I examine the effects of gender composition and peer achievement on high school students' outcomes in disadvantaged neighborhoods. Results show that having a higher proportion of female peers in the classroom improves girls' math test scores only in less-advanced courses. For male students, the estimated gender peer effects are positive but less precisely estimated. I also find no effect of average classroom achievement on female math test scores. Males, on the other hand, seem to benefit from a higher-achieving classroom. I propose mechanisms relating to lower gender stereotype influences and gender-specific attitudes toward competition as potential explanations for peer effects findings. Finally, having a higher proportion of female students in the classroom decreases student absenteeism among male students but has no impact on female attendance.

  1. Beneficial effects of Xuebijing injection on random skin flap survival in rats.

    PubMed

    Bin, Cao; Dingsheng, Lin; Leyi, Cai; Bin, Lin; Yuting, Lin; Liren, Wang; Zhijie, Li

    2015-06-15

    Improving survival of random skin flaps has important implications of reconstruction, and various kinds of agents have been tested for this purpose. In this study, the effects of Xuebijing (XBJ) injection on random skin flap survival in rats were evaluated. McFarlane flaps were established in 40 rats divided into two groups. XBJ was injected into the test group, and the same concentration of saline was injected into controls. Tissues were stained with hematoxylin and eosin stain and immunohistochemically evaluated, and the survival area of the flaps, superoxide dismutase, and malondialdehyde contents were examined. Compared with the control group, we found the mean survival area of the flaps in the test group was significantly larger, expression of vascular endothelial growth factor and superoxide dismutase activity increased markedly in the test group, malondialdehyde level in the test group was significantly lower, and the hematoxylin and eosin-stained slices showed that inflammation was clearly inhibited in the test group. In summary, XBJ improved survival of random skin flaps. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Monte Carlo particle transport in random media: The effects of mixing statistics

    NASA Astrophysics Data System (ADS)

    Larmier, Coline; Zoia, Andrea; Malvagi, Fausto; Dumonteil, Eric; Mazzolo, Alain

    2017-07-01

    Particle transport in random media obeying a given mixing statistics is key in several applications in nuclear reactor physics and more generally in diffusion phenomena emerging in optics and life sciences. Exact solutions for the ensemble-averaged physical observables are hardly available, and several approximate models have been thus developed, providing a compromise between the accurate treatment of the disorder-induced spatial correlations and the computational time. In order to validate these models, it is mandatory to use reference solutions in benchmark configurations, typically obtained by explicitly generating by Monte Carlo methods several realizations of random media, simulating particle transport in each realization, and finally taking the ensemble averages for the quantities of interest. In this context, intense research efforts have been devoted to Poisson (Markov) mixing statistics, where benchmark solutions have been derived for transport in one-dimensional geometries. In a recent work, we have generalized these solutions to two and three-dimensional configurations, and shown how dimension affects the simulation results. In this paper we will examine the impact of mixing statistics: to this aim, we will compare the reflection and transmission probabilities, as well as the particle flux, for three-dimensional random media obtained by using Poisson, Voronoi and Box stochastic tessellations. For each tessellation, we will furthermore discuss the effects of varying the fragmentation of the stochastic geometry, the material compositions, and the cross sections of the background materials.

  3. Effect of random errors in planar PIV data on pressure estimation in vortex dominated flows

    NASA Astrophysics Data System (ADS)

    McClure, Jeffrey; Yarusevych, Serhiy

    2015-11-01

    The sensitivity of pressure estimation techniques from Particle Image Velocimetry (PIV) measurements to random errors in measured velocity data is investigated using the flow over a circular cylinder as a test case. Direct numerical simulations are performed for ReD = 100, 300 and 1575, spanning laminar, transitional, and turbulent wake regimes, respectively. A range of random errors typical for PIV measurements is applied to synthetic PIV data extracted from numerical results. A parametric study is then performed using a number of common pressure estimation techniques. Optimal temporal and spatial resolutions are derived based on the sensitivity of the estimated pressure fields to the simulated random error in velocity measurements, and the results are compared to an optimization model derived from error propagation theory. It is shown that the reductions in spatial and temporal scales at higher Reynolds numbers leads to notable changes in the optimal pressure evaluation parameters. The effect of smaller scale wake structures is also quantified. The errors in the estimated pressure fields are shown to depend significantly on the pressure estimation technique employed. The results are used to provide recommendations for the use of pressure and force estimation techniques from experimental PIV measurements in vortex dominated laminar and turbulent wake flows.

  4. Randomized controlled trial of the effect of amniotomy on the duration of spontaneous labor.

    PubMed

    Vadivelu, Malarvizhi; Rathore, Swati; Benjamin, Santosh J; Abraham, Anuja; Belavendra, Antonisamy; Mathews, Jiji E

    2017-08-01

    To investigate the effect of amniotomy on the duration of spontaneous labor. In the present randomized controlled trial, women in spontaneous labor with singleton pregnancies presenting at a tertiary teaching hospital in South India between August 1, 2014, and October 31, 2015, were randomized in a 1:1 ratio to undergo amniotomy or conservative management. The primary outcome was the duration of labor. Per-protocol analyses were performed and the duration of labor was compared between the groups of patients. There were 144 patients randomized to each group. The median duration of labor was 235 minutes (interquartile range 117-355) in the amniotomy group and 364 minutes (interquartile range 201-580) in the conservative management group (P<0.001). Amniotomy was associated with a shorter duration of labor in comparison with conservative management in patients with singleton pregnancies experiencing spontaneous labor. Clinical Trials Registry-India: (CTRI) (CTRI/2014/12/005264). © 2017 International Federation of Gynecology and Obstetrics.

  5. Favorable effects of progesterone on skin random flap survival in rats

    PubMed Central

    Dingsheng, Lin; Zengbing, Liu; Dong, Huang

    2016-01-01

    Objective(s): The aim of this study is to determine the effects of progesterone treatment on the survival of random skin flaps. Materials and Methods: McFarlane flaps were established and 40 male rats were randomly assigned to the progesterone-treated as the test group or normal saline-treated as the control group. Progesterone or normal saline (10 mg/kg) was administered intraperitoneally once daily. On postoperative day 2, malondialdehyde (MDA) and superoxide dismutase (SOD) were detected using test kits. Flap survival rates were evaluated with transparent graph paper under direct visualization, the levels of inflammation were examined by haematoxylin and eosin (H&E) staining, and the expression of vascular endothelial growth factor (VEGF) was immunohistochemically evaluated on day 7. Results: Compared to that in the control group, the mean survival area was significantly larger in the progesterone group. SOD activity was increased significantly, but the MDA levels in the test group were decreased. H&E-stained slices revealed that inflammation was inhibited in the test group. VEGF expression markedly increased in the progesterone group. Conclusion: This study showed that progesterone administered intraperitoneally significantly improved random skin flap survival in rats. PMID:27917271

  6. Effects of acupuncture for initiation of labor: a double-blind randomized sham-controlled trial.

    PubMed

    Ajori, Ladan; Nazari, Leila; Eliaspour, Dariush

    2013-05-01

    This double-blind randomized controlled trial was conducted to evaluate whether use of acupuncture could initiate labor at term and thus reduce post-term induction. Between 2010 and 2011, a total of 80 women at 38 weeks of gestation or greater were randomized to acupuncture and sham acupuncture groups. Acupuncture points LI4, SP6 and BL67 were needled bilaterally. The primary outcome was initiation of labor. The time from acupuncture to delivery, mode of delivery, fetal and maternal outcome and Apgar scores were recorded. The trial is registered at irct.ir, number IRCT201111218151N1. Eighty women were randomized and 75 women completed the study procedure. Age, BMI, parity and gestational age were similar in both groups. Spontaneous labor was initiated in 94.7 % of acupuncture group and 89.2 % of sham acupuncture group (p = 0.430). There were no statistically significant difference between groups for time from enrollment to delivery (p = 0.06). According to this study, it seems that acupuncture was not effective in labor initiation compared to sham acupuncture.

  7. Effects of random dosimetry errors and the use of data on acute symptoms for dosimetry evaluation

    SciTech Connect

    Gilbert, E.S.

    1983-09-01

    Two approaches are used to address questions regarding dose measurement errors. The first is to describe and compare the effects of random error for several dose treatments including the use of grouped and ungrouped data, and analyses with and without truncation at 600 rad. It is found that the ways in which measurement error is most likely to mislead are through downward bias in the estimated regression coefficients and through distortion of the shape of the dose response curve. The second approach makes use of data on acute symptons to identify survivors in particular shielding situations or locations whose dose estimates may be especially biased or subject to unusual amounts of random error. It is found that the dose-response curves for acute symptoms differ considerably by many of the factors studied, but it is not possible to separate differences resulting from varying degrees of random error from systematic bias. The analyses also suggest that doses of Hiroshima survivors are in general better estimated than doses of Nagasaki survivors, a situation which could easily bias city comparisons. 17 references.

  8. The Effects of Inhalation Aromatherapy on Anxiety in Patients With Myocardial Infarction: A Randomized Clinical Trial

    PubMed Central

    Najafi, Zahra; Taghadosi, Mohsen; Sharifi, Khadijeh; Farrokhian, Alireza; Tagharrobi, Zahra

    2014-01-01

    Background: Anxiety is an important mental health problem in patients with cardiac disease. Anxiety reduces patients’ quality of life and increases the risk of different cardiac complications. Objectives: The aim of this study was to investigate the effects of inhalation aromatherapy on anxiety in patients with myocardial infarction. Patients and Methods: This was a randomized clinical trial conduced on 68 patients with myocardial infarction hospitalized in coronary care units of a large-scale teaching hospital affiliated to Kashan University of Medical Sciences, Kashan, Iran in 2013. By using the block randomization technique, patients were randomly assigned to experimental (33 patients receiving inhalation aromatherapy with lavender aroma twice a day for two subsequent days) and control (35 patients receiving routine care of study setting including no aromatherapy) groups. At the beginning of study and twenty minutes after each aromatherapy session, anxiety state of patients was assessed using the Spielberger’s State Anxiety Inventory. Data was analyzed using SPSS v. 16.0. We used Chi-square, Fisher’s exact, independent-samples T-test and repeated measures analysis of variance to analyze the study data. Results: The study groups did not differ significantly regarding baseline anxiety mean and demographic characteristics. However, after the administration of aromatherapy, anxiety mean in the experimental group was significantly lower than the control group. Conclusions: Inhalation aromatherapy with lavender aroma can reduce anxiety in patients with myocardial infarction. Consequently, healthcare providers, particularly nurses, can use this strategy to improve postmyocardial infarction anxiety management. PMID:25389481

  9. A randomized comparative effectiveness trial of using cable television to deliver diabetes prevention programming

    PubMed Central

    Ackermann, Ronald T; Sandy, Lewis G; Beauregard, Tom; Coblitz, Mark; Norton, Kristi L; Vojta, Deneen

    2014-01-01

    Objective To evaluate the use and effectiveness of two “in-home” strategies for delivering diabetes prevention programming using cable television. Methods An individually randomized, two-arm intervention trial including adults with diabetes risk factors living in two US cities. Interventions involved a 16-session lifestyle intervention delivered via “video-on-demand” cable television, offered alone versus in combination with web-based lifestyle support tools. Repeated measures longitudinal linear regression with imputation of missing observations was used to compare changes in body weight. Results A total of 306 individuals were randomized and offered the interventions. After 5 months, 265 (87%) participants viewed at least 1, and 110 (36%) viewed ≥9 of the video episodes. A total of 262 (86%) participants completed a 5-month weight measurement. In intention-to-treat analysis with imputation of missing observations, mean weight loss at 5 months for both treatment groups combined was 3.3% (95% CI 0.7-5.0%), regardless of intervention participation (with no differences between randomized groups (P = 0.19)), and was 4.9% (95% CI 2.1-6.5%) for participants who viewed ≥9 episodes. Conclusions In-home delivery of evidence-based diabetes prevention programming in a reality television format, offered with or without online behavioral support tools, can achieve modest weight losses consistent with past implementation studies of face-to-face programs using similar content. PMID:24740868

  10. The effect of extraction of third molars on late lower incisor crowding: a randomized controlled trial.

    PubMed

    Harradine, N W; Pearson, M H; Toth, B

    1998-05-01

    The problem of late mandibular incisor crowding is a well established phenomenon, the cause of which has been the substance of considerable debate over the years. A central issue is the possible role of the third molars though no definitive conclusions have been consistently drawn. This prospective study was designed to investigate the effects of randomly assigned early extraction of third molars on late crowding of the mandibular incisors. One-hundred-and-sixty-four patients entered the study from 1984 following completion of retention after orthodontic treatment. Seventy-seven patients (47%) returned for records up to a mean of 66 months later, and their start and finish study casts were digitized on a reflex microscope to determine Little's index of irregularity, intercanine width and arch length. Forty-four of the patients had been randomized to have third molars removed. There was no evidence of responder bias. Where third molars were extracted the mean increase in lower labial segment irregularity was reduced by 1.1 mm from a mean of 2.1 mm for the group where third molars were retained (P = 0.15, not statistically significant). This difference was also not considered to be clinically significant. The principal conclusion drawn from this randomized prospective study is that the removal of third molars to reduce or prevent late incisor crowding cannot be justified.

  11. A randomized comparative effectiveness trial of using cable television to deliver diabetes prevention programming.

    PubMed

    Ackermann, Ronald T; Sandy, Lewis G; Beauregard, Tom; Coblitz, Mark; Norton, Kristi L; Vojta, Deneen

    2014-07-01

    To evaluate the use and effectiveness of two "in-home" strategies for delivering diabetes prevention programming using cable television. An individually randomized, two-arm intervention trial including adults with diabetes risk factors living in two US cities. Interventions involved a 16-session lifestyle intervention delivered via "video-on-demand" cable television, offered alone versus in combination with web-based lifestyle support tools. Repeated measures longitudinal linear regression with imputation of missing observations was used to compare changes in body weight. A total of 306 individuals were randomized and offered the interventions. After 5 months, 265 (87%) participants viewed at least 1, and 110 (36%) viewed ≥9 of the video episodes. A total of 262 (86%) participants completed a 5-month weight measurement. In intention-to-treat analysis with imputation of missing observations, mean weight loss at 5 months for both treatment groups combined was 3.3% (95% CI 0.7-5.0%), regardless of intervention participation (with no differences between randomized groups (P = 0.19)), and was 4.9% (95% CI 2.1-6.5%) for participants who viewed ≥9 episodes. In-home delivery of evidence-based diabetes prevention programming in a reality television format, offered with or without online behavioral support tools, can achieve modest weight losses consistent with past implementation studies of face-to-face programs using similar content. © 2014 The Authors Obesity published by Wiley Periodicals, Inc. on behalf of The Obesity Society (TOS).

  12. Multilevel covariance regression with correlated random effects in the mean and variance structure.

    PubMed

    Quintero, Adrian; Lesaffre, Emmanuel

    2017-09-01

    Multivariate regression methods generally assume a constant covariance matrix for the observations. In case a heteroscedastic model is needed, the parametric and nonparametric covariance regression approaches can be restrictive in the literature. We propose a multilevel regression model for the mean and covariance structure, including random intercepts in both components and allowing for correlation between them. The implied conditional covariance function can be different across clusters as a result of the random effect in the variance structure. In addition, allowing for correlation between the random intercepts in the mean and covariance makes the model convenient for skewedly distributed responses. Furthermore, it permits us to analyse directly the relation between the mean response level and the variability in each cluster. Parameter estimation is carried out via Gibbs sampling. We compare the performance of our model to other covariance modelling approaches in a simulation study. Finally, the proposed model is applied to the RN4CAST dataset to identify the variables that impact burnout of nurses in Belgium. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Measured Vibration Effect of Numerous Sine Swept Harmonics on Random Shaker Applied to Effective Flight Model Representative Dummy

    NASA Astrophysics Data System (ADS)

    Polome, J.

    2012-07-01

    This paper presents the performance methodology and the achieved results of a vibration test campaign. The test performed by shaker simulates an unusual acoustic excitation containing a harmonic serial superimposed on random noise seen by electronic flight equipment. The paper is focused on main experimental aspects resulting of “helicopter simulation” capability applied on (representative) dummy electronic equipment. Wide internal instrumentation shows that the equipment is effectively answering to the stimuli by resonances excitation.

  14. The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial.

    PubMed

    Dhurandhar, Emily J; Dawson, John; Alcorn, Amy; Larsen, Lesli H; Thomas, Elizabeth A; Cardel, Michelle; Bourland, Ashley C; Astrup, Arne; St-Onge, Marie-Pierre; Hill, James O; Apovian, Caroline M; Shikany, James M; Allison, David B

    2014-08-01

    Breakfast is associated with lower body weight in observational studies. Public health authorities commonly recommend breakfast consumption to reduce obesity, but the effectiveness of adopting these recommendations for reducing body weight is unknown. We tested the relative effectiveness of a recommendation to eat or skip breakfast on weight loss in adults trying to lose weight in a free-living setting. We conducted a multisite, 16-wk, 3-parallel-arm randomized controlled trial in otherwise healthy overweight and obese adults [body mass index (in kg/m²) between 25 and 40] aged 20-65 y. Our primary outcome was weight change. We compared weight change in a control group with weight loss in experimental groups told to eat breakfast or to skip breakfast [no breakfast (NB)]. Randomization was stratified by prerandomization breakfast eating habits. A total of 309 participants were randomly assigned. A total of 283 of the 309 participants who were randomly assigned completed the intervention. Treatment assignment did not have a significant effect on weight loss, and there was no interaction between initial breakfast eating status and treatment. Among skippers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were -0.71 ± 1.16, -0.76 ± 1.26, and -0.61 ± 1.18 kg for the control, breakfast, and NB groups, respectively. Among breakfast consumers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were -0.53 ± 1.16, -0.59 ± 1.06, and -0.71 ± 1.17 kg for the control, breakfast, and NB groups, respectively. Self-reported compliance with the recommendation was 93.6% for the breakfast group and 92.4% for the NB group. A recommendation to eat or skip breakfast for weight loss was effective at changing self-reported breakfast eating habits, but contrary to widely espoused views this had no discernable effect on weight loss in free-living adults who were attempting to lose weight. © 2014 American Society for

  15. The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial123

    PubMed Central

    Dhurandhar, Emily J; Dawson, John; Alcorn, Amy; Larsen, Lesli H; Thomas, Elizabeth A; Cardel, Michelle; Bourland, Ashley C; Astrup, Arne; St-Onge, Marie-Pierre; Hill, James O; Apovian, Caroline M; Shikany, James M; Allison, David B

    2014-01-01

    Background: Breakfast is associated with lower body weight in observational studies. Public health authorities commonly recommend breakfast consumption to reduce obesity, but the effectiveness of adopting these recommendations for reducing body weight is unknown. Objective: We tested the relative effectiveness of a recommendation to eat or skip breakfast on weight loss in adults trying to lose weight in a free-living setting. Design: We conducted a multisite, 16-wk, 3-parallel-arm randomized controlled trial in otherwise healthy overweight and obese adults [body mass index (in kg/m2) between 25 and 40] aged 20–65 y. Our primary outcome was weight change. We compared weight change in a control group with weight loss in experimental groups told to eat breakfast or to skip breakfast [no breakfast (NB)]. Randomization was stratified by prerandomization breakfast eating habits. A total of 309 participants were randomly assigned. Results: A total of 283 of the 309 participants who were randomly assigned completed the intervention. Treatment assignment did not have a significant effect on weight loss, and there was no interaction between initial breakfast eating status and treatment. Among skippers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were −0.71 ± 1.16, −0.76 ± 1.26, and −0.61 ± 1.18 kg for the control, breakfast, and NB groups, respectively. Among breakfast consumers, mean (±SD) baseline weight-, age-, sex-, site-, and race-adjusted weight changes were −0.53 ± 1.16, −0.59 ± 1.06, and −0.71 ± 1.17 kg for the control, breakfast, and NB groups, respectively. Self-reported compliance with the recommendation was 93.6% for the breakfast group and 92.4% for the NB group. Conclusions: A recommendation to eat or skip breakfast for weight loss was effective at changing self-reported breakfast eating habits, but contrary to widely espoused views this had no discernable effect on weight loss in free-living adults who

  16. The effectiveness of lifestyle triple P in the Netherlands: a randomized controlled trial.

    PubMed

    Gerards, Sanne M P L; Dagnelie, Pieter C; Gubbels, Jessica S; van Buuren, Stef; Hamers, Femke J M; Jansen, Maria W J; van der Goot, Odilia H M; de Vries, Nanne K; Sanders, Matthew R; Kremers, Stef P J

    2015-01-01

    Lifestyle Triple P is a general parenting intervention which focuses on preventing further excessive weight gain in overweight and obese children. The objective of the current study was to assess the effectiveness of the Lifestyle Triple P intervention in the Netherlands. We used a parallel randomized controlled design to test the effectiveness of the intervention. In total, 86 child-parent triads (children 4-8 years old, overweight or obese) were recruited and randomly assigned (allocation ratio 1:1) to the Lifestyle Triple P intervention or the control condition. Parents in the intervention condition received a 14-week intervention consisting of ten 90-minute group sessions and four individual telephone sessions. Primary outcome measure was the children's body composition (BMI z-scores, waist circumference and skinfolds). The research assistant who performed the measurements was blinded for group assignment. Secondary outcome measures were the children's dietary behavior and physical activity level, parenting practices, parental feeding style, parenting style, and parental self-efficacy. Outcome measures were assessed at baseline and 4 months (short-term) and 12 months (long-term) after baseline. Multilevel multiple regression analyses were conducted to determine the effect of the intervention on primary and secondary outcome measures. No intervention effects were found on children's body composition. Analyses of secondary outcomes showed positive short-term intervention effects on children's soft-drink consumption and parental responsibility regarding physical activity, encouragement to eat, psychological control, and efficacy and satisfaction with parenting. Longer-term intervention effects were found on parent's report of children's time spent on sedentary behavior and playing outside, parental monitoring food intake, and responsibility regarding nutrition. Although the Lifestyle Triple P intervention showed positive effects on some parent reported child

  17. Can attention control conditions have detrimental effects on behavioral medicine randomized trials?

    PubMed

    Pagoto, Sherry L; McDermott, Mary M; Reed, George; Greenland, Philip; Mazor, Kathy M; Ockene, Judith K; Whited, Matt; Schneider, Kristin; Appelhans, Brad; Leung, Kathy; Merriam, Philip; Ockene, Ira

    2013-02-01

    Attention control (AC) conditions are used to balance nonspecific attention in randomized trials of behavioral interventions. Very little guidance about which behavioral interventions and outcomes merit AC is available in the literature. The primary aim of the present study is to demonstrate a scenario in which use of AC in a behavioral randomized trial was unnecessary and possibly detrimental. Exploratory analyses were performed in a randomized controlled trial that tested whether a patient-centered counseling intervention reduced low-density lipoprotein cholesterol levels in 355 participants with peripheral arterial disease, compared with AC and usual care (UC) conditions. The patient-centered counseling intervention was designed to activate participants to ask their physician for lipid-lowering medication and/or increase dose intensity, increase medication adherence, and reduce fat intake. The AC condition involved attention-matched telephone-delivered health education, and the UC condition consisted of an educational pamphlet. At 12-month follow-up, the mean low-density lipoprotein cholesterol changes were -11.1 and -6.8 mg/dL in the UC and AC conditions, respectively (p=.17). The proportion of participants who increased the use or dose intensity of medication was significantly lower in AC than in UC: 17.5% versus 30.5% (p=.03). No significant difference in other outcomes was observed between AC and UC. AC has significantly worse medication outcomes, and there is no indication of a therapeutic effect on other end points. Implications for the use of AC in behavioral randomized trials are discussed. clinicaltrials.gov Identifier: NCT00217919.

  18. Effect of an Immersive Preoperative Virtual Reality Experience on Patient Reported Outcomes: A Randomized Controlled Trial.

    PubMed

    Bekelis, Kimon; Calnan, Daniel; Simmons, Nathan; MacKenzie, Todd A; Kakoulides, George

    2017-06-01

    To investigate the effect of exposure to a virtual reality (VR) environment preoperatively on patient-reported outcomes for surgical operations. There is a scarcity of well-developed quality improvement initiatives targeting patient satisfaction. We performed a randomized controlled trial of patients undergoing cranial and spinal operations in a tertiary referral center. Patients underwent a 1:1 randomization to an immersive preoperative VR experience or standard preoperative experience stratified on type of operation. The primary outcome measures were the Evaluation du Vecu de l'Anesthesie Generale (EVAN-G) score and the Amsterdam Preoperative Anxiety and Information (APAIS) score, as markers of the patient's experience during the surgical encounter. During the study period, a total of 127 patients (mean age 55.3 years, 41.9% females) underwent randomization. The average EVAN-G score was 84.3 (standard deviation, SD, 6.4) after VR, and 64.3 (SD, 11.7) after standard preoperative experience (difference, 20.0; 95% confidence interval, CI, 16.6-23.3). Exposure to an immersive VR experience also led to higher APAIS score (difference, 29.9; 95% CI, 24.5-35.2). In addition, VR led to lower preoperative VAS stress score (difference, -41.7; 95% CI, -33.1 to -50.2), and higher preoperative VAS preparedness (difference, 32.4; 95% CI, 24.9-39.8), and VAS satisfaction (difference, 33.2; 95% CI, 25.4-41.0) scores. No association was identified with VAS stress score (difference, -1.6; 95% CI, -13.4 to 10.2). In a randomized controlled trial, we demonstrated that patients exposed to preoperative VR had increased satisfaction during the surgical encounter. Harnessing the power of this technology, hospitals can create an immersive environment that minimizes stress, and enhances the perioperative experience.

  19. Can attention control conditions have detrimental effects in behavioral medicine randomized trials?

    PubMed Central

    Pagoto, Sherry; McDermott, Mary M.; Reed, George; Greenland, Philip; Mazor, Kathy M.; Ockene, Judith K.; Whited, Matt; Schneider, Kristin; Appelhans, Brad; Leung, Kathy; Merriam, Philip; Ockene, Ira

    2012-01-01

    Objective Attention control conditions are used to balance nonspecific attention in randomized trials of behavioral interventions. Very little guidance is available in the literature about which behavioral interventions and outcomes merit an attention control. The primary aim of the present paper is to demonstrate a scenario in which use of attention control in a behavioral randomized trial was unnecessary and possibly detrimental. Methods Exploratory analyses were performed in a randomized controlled trial that tested whether a patient-centered telephone counseling (PC) intervention reduced low-density lipoprotein cholesterol (LDL-C) levels in 355 participants with peripheral arterial disease (PAD), compared to attention control (AC) and usual care (UC) conditions. The PC intervention was designed to activate participants to ask their physician for lipid-lowering medication and/or increase dose intensity, increase medication adherence, and reduce fat intake. The AC condition involved attention-matched phone-delivered health education, and the UC condition consisted of an educational pamphlet. Results At 12-month follow-up, mean LDL-C changes were −11.1, and −6.8 mg/dl in the UC and AC conditions, respectively (p=.17). The proportion of participants who increased use or dose intensity of medication was significantly lower in AC than UC, 17.5% versus 30.5% (p=0.03). No significant difference between AC and UC were observed on other outcomes. Conclusions The AC had significantly worse medication outcomes and there was no indication of a therapeutic effect on other endpoints. Implications for use of attention control in behavioral randomized trials are discussed. PMID:23197844

  20. Effect of Dietary Protein Supplementation on Blood Pressure: A Randomized Controlled Trial

    PubMed Central

    He, Jiang; Wofford, Marion R.; Reynolds, Kristi; Chen, Jing; Chen, Chung-Shiuan; Myers, Leann; Minor, Deborah L.; Elmer, Patricia J.; Jones, Daniel W.; Whelton, Paul K.

    2011-01-01

    Background Observational studies have reported an inverse association between dietary protein intake and blood pressure (BP). We compared the effect of soy protein, milk protein, and carbohydrate supplementation on BP among healthy adults. Methods and Results We conducted a randomized double-blind crossover trial with 3-intervention phases among 352 adults with prehypertension or stage-1 hypertension in New Orleans, Louisiana and Jackson, Mississippi from September 2003 to April 2008. The trial participants were assigned to take 40 grams/day of soy protein, milk protein, or carbohydrate supplementation each for 8 weeks in a random order. A 3-week washout period was implemented between the interventions. Three BPs were measured at 2 baseline and 2 termination visits during each of 3 intervention phases using a random-zero sphygmomanometer. Compared to carbohydrate controls, soy protein and milk protein supplementations were significantly associated with −2.0 mmHg (95% confidence interval −3.2 to −0.7, p=0.002) and −2.3 mmHg (−3.7 to −1.0, p=0.0007) net change in systolic BP, respectively. Diastolic BP was also reduced but this change did not reach statistical significance. There was no significant difference in the BP reductions achieved between soy or milk protein supplementation. Conclusions The results from this randomized controlled trial indicate that both soy and milk protein intake reduce systolic BP compared to a high glycemic index refined carbohydrate among patients with prehypertension and stage-1 hypertension. Furthermore, these findings suggest that partially replacing carbohydrate with soy or milk protein might be an important component of nutrition intervention strategies for the prevention and treatment of hypertension. PMID:21768541

  1. Comparative cost-effectiveness of three intrauterine devices: a multi-center randomized trial.

    PubMed

    Wen, Jin; Li, Ying; Li, Youping; Wang, Li; Zhou, Jian; Ba, Lei; Shen, Suqi; Wu, Yulin

    2010-05-01

    To determine the relative cost-effectiveness of three intrauterine devices (IUDs), MLCu375, TCu380A, and YuangongCu365. Cost-effectiveness of three IUDs, namely MLCu375, TCu380A, and YuangongCu365, was analyzed from the provider's perspective by means of a randomized trial with one-year follow-up carried out in six centers in China. YuangongCu 365 had the lowest termination and pregnancy rates (4.17% and 0.54%, respectively), followed by TCu380A (8.59% and 1.11%, respectively) and MLCu375 (14.17% and 2.04%, respectively). YuangongCu365 was more effective yet more costly than the MLCu375. There was a favorably dominating trend of cost-effectiveness for TCu380A comparing with MLCu375 when taking continuation rate as the effectiveness indicator, but there was no difference in cost-effectiveness between the two IUDs when using the pregnancy avoidance rate as the effectiveness measure. TCu380A is slightly more cost-effective than the MLCu375. YuangongCu365 is the most effective of the three devices and be used provided it is economically affordable. The comparative long-term safety and cost-effectiveness of these devices need to be further investigated. © 2010 Blackwell Publishing Asia Pty Ltd and Chinese Cochrane Center, West China Hospital of Sichuan University.

  2. Postural stability effects of random vibration at the feet of construction workers in simulated elevation.

    PubMed

    Simeonov, P; Hsiao, H; Powers, J; Ammons, D; Kau, T; Amendola, A

    2011-07-01

    The risk of falls from height on a construction site increases under conditions which degrade workers' postural control. At elevation, workers depend heavily on sensory information from their feet to maintain balance. The study tested two hypotheses: "sensory enhancement"--sub-sensory (undetectable) random mechanical vibrations at the plantar surface of the feet can improve worker's balance at elevation; and "sensory suppression"--supra-sensory (detectable) random mechanical vibrations can have a degrading effect on balance in the same experimental settings. Six young (age 20-35) and six aging (age 45-60) construction workers were tested while standing in standard and semi-tandem postures on instrumented gel insoles. The insoles applied sub- or supra-sensory levels of random mechanical vibrations to the feet. The tests were conducted in a surround-screen virtual reality system, which simulated a narrow plank at elevation on a construction site. Upper body kinematics was assessed with a motion-measurement system. Postural stability effects were evaluated by conventional and statistical mechanics sway measures, as well as trunk angular displacement parameters. Analysis of variance did not confirm the "sensory enhancement" hypothesis, but provided evidence for the "sensory suppression" hypothesis. The supra-sensory vibration had a destabilizing effect, which was considerably stronger in the semi-tandem posture and affected most of the sway variables. Sensory suppression associated with elevated vibration levels on a construction site may increase the danger of losing balance. Construction workers at elevation, e.g., on a beam or narrow plank might be at increased risk of fall if they can detect vibrations under their feet. To reduce the possibility of losing balance, mechanical vibration to supporting structures used as walking/working surfaces should be minimized when performing construction tasks at elevation. Published by Elsevier Ltd.

  3. Effectiveness of myofascial release in the management of plantar heel pain: a randomized controlled trial.

    PubMed

    Ajimsha, M S; Binsu, D; Chithra, S

    2014-06-01

    Previous studies have reported that stretching of the calf musculature and the plantar fascia are effective management strategies for plantar heel pain (PHP). However, it is unclear whether myofascial release (MFR) can improve the outcomes in this population. To investigate whether myofascial release (MFR) reduces the pain and functional disability associated with plantar heel pain (PHP) in comparison with a control group receiving sham ultrasound therapy (SUST). Randomized, controlled, double blinded trial. Nonprofit research foundation clinic in India. Sixty-six patients, 17 men and 49 women with a clinical diagnosis of PHP were randomly assigned into MFR or a control group and given 12 sessions of treatment per client over 4 weeks. The Foot Function Index (FFI) scale was used to assess pain severity and functional disability. The primary outcome measure was the difference in FFI scale scores between week 1 (pretest score), week 4 (posttest score), and follow-up at week 12 after randomization. Additionally, pressure pain thresholds (PPT) were assessed over the affected gastrocnemii and soleus muscles, and over the calcaneus, by an assessor blinded to the treatment allocation. The simple main effects analysis showed that the MFR group performed better than the control group in weeks 4 and 12 (P<0.001). Patients in the MFR and control groups reported a 72.4% and 7.4% reduction, respectively, in their pain and functional disability in week 4 compared with that in week 1, which persisted as 60.6% in the follow-up at week 12 in the MFR group compared to the baseline. The mixed ANOVA also revealed significant group-by-time interactions for changes in PPT over the gastrocnemii and soleus muscles, and the calcaneus (P<0.05). This study provides evidence that MFR is more effective than a control intervention for PHP. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Effect of music in endoscopy procedures: systematic review and meta-analysis of randomized controlled trials.

    PubMed

    Wang, Man Cai; Zhang, Ling Yi; Zhang, Yu Long; Zhang, Ya Wu; Xu, Xiao Dong; Zhang, You Cheng

    2014-10-01

    Endoscopies are common clinical examinations that are somewhat painful and even cause fear and anxiety for patients. We performed this systematic review and meta-analysis of randomized controlled trials to determine the effect of music on patients undergoing various endoscopic procedures. We searched the Cochrane Library, Issue 6, 2013, PubMed, and EMBASE databases up to July 2013. Randomized controlled trials comparing endoscopies, with and without the use of music, were included. Two authors independently abstracted data and assessed risk of bias. Subgroup analyses were performed to examine the impact of music on different types of endoscopic procedures. Twenty-one randomized controlled trials involving 2,134 patients were included. The overall effect of music on patients undergoing a variety of endoscopic procedures significantly improved pain score (weighted mean difference [WMD] = -1.53, 95% confidence interval [CI] [-2.53, -0.53]), anxiety (WMD = -6.04, 95% CI [-9.61, -2.48]), heart rate (P = 0.01), arterial pressure (P < 0.05), and satisfaction score (SMD = 1.83, 95% CI [0.76, 2.91]). Duration of the procedure (P = 0.29), except for gastrointestinal endoscopy (P = 0.03), and sedative or analgesic medication dose (P = 0.23, P = 0.12, respectively) were not significantly decreased in the music group, compared with the control group. Furthermore, music had little effect for patients undergoing colposcopy and bronchoscopy in the subanalysis. Our meta-analysis suggested that music may offer benefits for patients undergoing endoscopy, except in colposcopy and bronchoscopy. Wiley Periodicals, Inc.

  5. Is customized vestibular rehabilitation effective in patients with multiple sclerosis? A randomized controlled trial.

    PubMed

    Ozgen, Gulnur; Karapolat, Hale; Akkoc, Yesim; Yuceyar, Nur

    2016-08-01

    Balance disorders are among the most common problems encountered by patients diagnosed with multiple sclerosis (MS). The purpose of this randomized, controlled trial was to investigate the effects of customized vestibular rehabilitation (VR) on balance, functional capacity, quality of life, and depression in patients with MS. This study was designed as a prospective, randomized, controlled trial. The study was carried out in a single tertiary referral center. Forty consecutive patients referred with a diagnosis of MS were randomized into two groups: an exercise group (N.=20) and a control group (N.=20). The experimental group underwent customized VR and the wait-listed control group received the usual medical care. All of the patients were assessed with objective balance tests (Romberg Test, Tandem Romberg Test, Foam Romberg Test, Static Posturography, Six-Meter Walk Test, Five Times Sit-to-Stand Test, Berg Balance Scale, Timed Up and Go Test, Functional Gait Assessment, and Dynamic Gait Index), subjective balance parameters (Activities-Specific Balance Confidence Scale and Dizziness Handicap Inventory), and functional capacity (Six-Minute Walking Test), quality of life (Multiple Sclerosis Quality of Life-54), and depression (Beck Depression Inventory) scales. At the end of the trial, the exercise group exhibited significant changes in most of the evaluated parameters compared to the control group [except the Tandem Romberg with eyes closed and the Foam Romberg, standing with eyes open (P<0.05). No significant differences were observed in any of the parameters in the control group (P>0.05). The intergroup comparisons of differences indicated significant recoveries in favor of the exercise group in all of the evaluated parameters (P<0.05). This study confirms the effects of customized VR programs on balance, quality of life, and functional capacity in patients with MS. Customized VR is an effective method for treating balance disorders in patients with MS.

  6. A Bayesian hierarchical method to account for random effects in cytogenetic dosimetry based on calibration curves.

    PubMed

    Mano, Shuhei; Suto, Yumiko

    2014-11-01

    The dicentric chromosome assay (DCA) is one of the most sensitive and reliable methods of inferring doses of radiation exposure in patients. In DCA, one calibration curve is prepared in advance by in vitro irradiation to blood samples from one or sometimes multiple healthy donors in considering possible inter-individual variability. Although the standard method has been demonstrated to be quite accurate for actual dose estimates, it cannot account for random effects, which come from such as the blood donor used to prepare the calibration curve, the radiation-exposed patient, and the examiners. To date, it is unknown how these random effects impact on the standard method of dose estimation. We propose a novel Bayesian hierarchical method that incorporates random effects into the dose estimation. To demonstrate dose estimation by the proposed method and to assess the impact of inter-individual variability in samples from multiple donors on the estimation, peripheral blood samples from 13 occupationally non-exposed, non-smoking, healthy individuals were collected and irradiated with gamma rays. The results clearly showed significant inter-individual variability and the standard method using a sample from a single donor gave anti-conservative confidence interval of the irradiated dose. In contrast, the Bayesian credible interval for irradiated dose calculated by the proposed method using samples from multiple donors properly covered the actual doses. Although the classical confidence interval of calibration curve with accounting inter-individual variability in samples from multiple donors was roughly coincident with the Bayesian credible interval, the proposed method has better reasoning and potential for extensions.

  7. Effectiveness and cost-effectiveness of telehealthcare for chronic obstructive pulmonary disease: study protocol for a cluster randomized controlled trial.

    PubMed

    Udsen, Flemming Witt; Lilholt, Pernille Heyckendorff; Hejlesen, Ole; Ehlers, Lars Holger

    2014-05-21

    Several feasibility studies show promising results of telehealthcare on health outcomes and health-related quality of life for patients suffering from chronic obstructive pulmonary disease, and some of these studies show that telehealthcare may even lower healthcare costs. However, the only large-scale trial we have so far - the Whole System Demonstrator Project in England - has raised doubts about these results since it conclude that telehealthcare as a supplement to usual care is not likely to be cost-effective compared with usual care alone. The present study is known as 'TeleCare North' in Denmark. It seeks to address these doubts by implementing a large-scale, pragmatic, cluster-randomized trial with nested economic evaluation. The purpose of the study is to assess the effectiveness and the cost-effectiveness of a telehealth solution for patients suffering from chronic obstructive pulmonary disease compared to usual practice. General practitioners will be responsible for recruiting eligible participants (1,200 participants are expected) for the trial in the geographical area of the North Denmark Region. Twenty-six municipality districts in the region define the randomization clusters. The primary outcomes are changes in health-related quality of life, and the incremental cost-effectiveness ratio measured from baseline to follow-up at 12 months. Secondary outcomes are changes in mortality and physiological indicators (diastolic and systolic blood pressure, pulse, oxygen saturation, and weight). There has been a call for large-scale clinical trials with rigorous cost-effectiveness assessments in telehealthcare research. This study is meant to improve the international evidence base for the effectiveness and cost-effectiveness of telehealthcare to patients suffering from chronic obstructive pulmonary disease by implementing a large-scale pragmatic cluster-randomized clinical trial. Clinicaltrials.gov, http://NCT01984840, November 14, 2013.

  8. Coherent light scattering of heterogeneous randomly rough films and effective medium in the theory of electromagnetic wave multiple scattering

    NASA Astrophysics Data System (ADS)

    Berginc, G.

    2013-11-01

    We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell - Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength.

  9. Coherent light scattering of heterogeneous randomly rough films and effective medium in the theory of electromagnetic wave multiple scattering

    SciTech Connect

    Berginc, G

    2013-11-30

    We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell – Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength. (coherent light scattering)

  10. Effects of an Integrated Stress Management Program (ISMP) for Psychologically Distressed Students: A Randomized Controlled Trial.

    PubMed

    Kim, Sunah; Lee, Hyangkyu; Kim, Hyunlye; Noh, Dabok; Lee, Hyunhwa

    2016-07-01

    This study aimed to evaluate the effects of an integrated stress management program (ISMP) on college life stress, stress coping, psychological distress, and cortisol among male college students. Out of 137 initially enrolled students, 99 participants were identified as distressed subjects and randomly assigned to either the ISMP or control group. Ultimately, 84 participants (43: experimental, 41: control) completed pretest-posttest. The experimental group received eight 2-hr sessions over 4 weeks. Stress and psychological distress decreased significantly, whereas stress coping and cortisol did not improve significantly. Further studies with longer follow-up periods and physiological interventions are required. © 2015 Wiley Periodicals, Inc.

  11. Effectiveness of music interventions for women with high anxiety during coronary angiographic procedures: a randomized controlled.

    PubMed

    Nilsson, Ulrica

    2012-06-01

    The purpose was to investigate if women with high pre-procedural anxiety reported higher degree of relaxation and comfort if listening to music during coronary angiographic procedures. A prospective randomized controlled trial was used included 68 patients undergoing coronary angiography and/or PCI. The women were allocated to receive calming music and standard care or standard care only. Relaxation, environmental sound and discomfort associated with lying still were assessed. There was significantly more positive impression of the sound environment and less discomfort associated with lying still in women listening to music in comparison to women who received only standard care. No effect in relaxation was found.

  12. Effect of guided relaxation and imagery on falls self-efficacy: a randomized controlled trial.

    PubMed

    Kim, Bang Hyun; Newton, Roberta A; Sachs, Michael L; Glutting, Joseph J; Glanz, Karen

    2012-06-01

    To examine the effects of guided relaxation and imagery (GRI) on improvement in falls self-efficacy in older adults who report having a fear of falling. Randomized, controlled trial with allocation to GRI or guided relaxation with music of choice. General community. Ninety-one men and women aged 60 to 92. Participants were randomized to listen to a GRI audio compact disk (intervention group) or a guided relaxation audio compact disk and music of choice (control group) twice a week for 6 weeks for 10 minutes per session. Primary outcome measure was the Short Falls Efficacy Scale-International (FES-I). Secondary outcome measures were the Leisure Time Exercise Questionnaire (LTEQ) and the Timed Up and Go (TUG) mobility test. GRI participants reported greater improvements on the Short FES-I (P = .002) and LTEQ (P = .001) scores and shorter time on the TUG (P = .002) than the guided relaxation and music-of-choice group. GRI was more effective at increasing falls self-efficacy and self-reported leisure time exercise and reducing times on a simple mobility test than was guided relaxation with music of choice. GRI is an effective, simple, low-cost tool for older adults to improve falls self-efficacy and leisure time exercise behaviors. © 2012, Copyright the Authors Journal compilation © 2012, The American Geriatrics Society.

  13. Psychiatric symptoms moderate the effects of mental illness self-management in a randomized controlled trial.

    PubMed

    Steigman, Pamela J; Pickett, Susan A; Diehl, Sita M; Fox, Anthony; Grey, Dennis D; Shipley, Patricia; Cook, Judith A

    2014-03-01

    Depression has been shown to moderate the effects of physical illness self-management (ISM) programs. We attempted to replicate these findings for a mental ISM intervention. Outpatients with serious mental illness (N = 428) from eight Tennessee communities were randomly assigned to receive a peer-led self-management intervention called Building Recovery of Individual Dreams and Goals Through Education and Support or services as usual. Psychiatric symptoms were assessed with the Brief Symptom Inventory; the outcome of personal empowerment was measured by the Empowerment Scale. Intent-to-treat analysis using mixed-effects random regression found significant interaction effects between study condition and three moderating symptom profiles. Empowerment was greater for the intervention participants with high levels of depressive symptoms, anxiety symptoms, and general symptom distress than for the experimental participants with low symptom levels and the control subjects with high or low levels of symptoms. These results shed light on how mental ISM programs operate and ways these can be improved.

  14. The effectiveness of core stabilization exercise in adolescent idiopathic scoliosis: A randomized controlled trial.

    PubMed

    Gür, Gözde; Ayhan, Cigdem; Yakut, Yavuz

    2017-06-01

    Core stabilization training is used to improve postural balance in musculoskeletal problems. The purpose of this study was to investigate the effectiveness of stabilization training in adolescent idiopathic scoliosis. A randomized controlled trial, pretest-posttest design. In total, 25 subjects with adolescent idiopathic scoliosis were randomly divided into two groups: stabilization group ( n = 12) and control group ( n = 13). The stabilization group received core stabilization in addition to traditional rehabilitation, and the control group received traditional rehabilitation for 10 weeks. Assessment included Cobb's angle on radiograph, apical vertebral rotation in Adam's test, trunk asymmetry (Posterior Trunk Symmetry Index), cosmetic trunk deformity (Trunk Appearance Perception Scale), and quality of life (Scoliosis Research Society-22 questionnaire). Inter-group comparisons showed significantly greater improvements in the mean change in lumbar apical vertebral rotation degree and the pain domain of Scoliosis Research Society-22 in the stabilization group than those in the control group ( p < 0.05). No significant differences were observed for other measurements between the groups; however, trends toward greater improvement were observed in the stabilization group. Core stabilization training in addition to traditional exercises was more effective than traditional exercises alone in the correction of vertebral rotation and reduction of pain in adolescent idiopathic scoliosis. Clinical relevance Stabilization exercises are more effective in reducing rotation deformity and pain than traditional exercises in the conservative rehabilitation of adolescent idiopathic scoliosis. These improvements suggest that stabilization training should be added to rehabilitation programs in adolescent idiopathic scoliosis.

  15. Clinical effectiveness of dermal substitution in burns by topical negative pressure: a multicenter randomized controlled trial.

    PubMed

    Bloemen, Monica C T; van der Wal, Martijn B A; Verhaegen, Pauline D H M; Nieuwenhuis, Marianne K; van Baar, Margriet E; van Zuijlen, Paul P M; Middelkoop, Esther

    2012-01-01

    Previous research has shown clinical effectiveness of dermal substitution; however, in burn wounds, only limited effect has been shown. A problem in burn wounds is the reduced take of the autograft, when the substitute and graft are applied in one procedure. Recently, application of topical negative pressure (TNP) was shown to improve graft take. The aim of this study was to investigate if application of a dermal substitute in combination with TNP improves scar quality after burns. In a four-armed multicenter randomized controlled trial, a split-skin graft with or without a dermal substitute and with or without TNP was compared in patients with deep dermal or full-thickness burns requiring skin transplantation. Graft take and rate of wound epithelialization were evaluated. Three and 12 months postoperatively, scar parameters were measured. The results of 86 patients showed that graft take and epithelialization did not reveal significant differences. Significantly fewer wounds in the TNP group showed postoperative contamination, compared to other groups. Highest elasticity was measured in scars treated with the substitute and TNP, which was significantly better compared to scars treated with the substitute alone. Concluding, this randomized controlled trial shows the effectiveness of dermal substitution combined with TNP in burns, based on extensive wound and scar measurements. © 2012 by the Wound Healing Society.

  16. Effective pore-scale dispersion upscaling with a correlated continuous time random walk approach

    NASA Astrophysics Data System (ADS)

    Le Borgne, T.; Bolster, D.; Dentz, M.; de Anna, P.; Tartakovsky, A.

    2011-12-01

    We investigate the upscaling of dispersion from a pore-scale analysis of Lagrangian velocities. A key challenge in the upscaling procedure is to relate the temporal evolution of spreading to the pore-scale velocity field properties. We test the hypothesis that one can represent Lagrangian velocities at the pore scale as a Markov process in space. The resulting effective transport model is a continuous time random walk (CTRW) characterized by a correlated random time increment, here denoted as correlated CTRW. We consider a simplified sinusoidal wavy channel model as well as a more complex heterogeneous pore space. For both systems, the predictions of the correlated CTRW model, with parameters defined from the velocity field properties (both distribution and correlation), are found to be in good agreement with results from direct pore-scale simulations over preasymptotic and asymptotic times. In this framework, the nontrivial dependence of dispersion on the pore boundary fluctuations is shown to be related to the competition between distribution and correlation effects. In particular, explicit inclusion of spatial velocity correlation in the effective CTRW model is found to be important to represent incomplete mixing in the pore throats.

  17. Effects of micro- and subtle-expression reading skill training in medical students: A randomized trial.

    PubMed

    Yu, Eun Ho; Choi, Eun Jung; Lee, Sang Yeoup; Im, Sun Ju; Yune, So Jung; Baek, Sun Yong

    2016-10-01

    to investigate the effectiveness of the Micro Expression Training Tool (METT) and the Subtle Expression Training Tool (SETT) to help improve the non-verbal communication skills of medical students. In a randomized controlled trial, all participants were randomly allocated to either a training (n=41) or control group (n=41) and were pre-tested before education with METT and SETT at baseline. Then, training students took second tests after a 1-h class about interpreting micro and subtle expressions and control students took the second tests without the class. METT pre-test scores were positively related with female gender, agreeableness, whereas SETT pre-test scores were negatively related with age and positively related with female gender. Mean METT score increases of 29.3% and mean SETT score increases of 36.2% were observed after training, whereas the control group achieved only a mean METT score increase of 11.0% at second testing. Increases in both test scores in the training group were significantly higher than in the control group. METT and SETT are effective, simple tools for improving the micro- and subtle-expression reading skills of medical students. METT and SETT can be effective for improving the non-verbal communication skills of medical students. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  18. Effects of music on physiological and behavioral responses of premature infants: a randomized controlled trial.

    PubMed

    Alipour, Zahra; Eskandari, Narges; Ahmari Tehran, Hoda; Eshagh Hossaini, Seyed Kamal; Sangi, Sareh

    2013-08-01

    Despite persuasive theories about the beneficial effects of music and singing in developmental care for premature infants, few small studies are available in this regard. We conducted this study to investigate the physiological and behavioral responses of premature infants to recorded lullaby music and silence. In a randomized controlled trial, 90 premature infants in the neonatal care unit of a hospital in Qom (Iran) were randomly allocated to intervention (lullaby and silence) or control groups. Lullaby music was played via headphones at a volume of 50-60 dB. In the silence group, headphones were placed on the infants' ears while no music was played. The three groups were surveyed for physiological responses including oxygen saturation, respiratory and heart rates, and behavioral states every five minutes before, during, and after the intervention. The three groups were not significantly different in terms of mean values of respiratory and heart rates, oxygen saturation, and behavioral states of infants. Similarly, no significant within group differences in respiratory and heart rates, oxygen saturation, and behavioral states were observed at different times. Our findings did not support the beneficial effects of music for premature infants. However, music is a noninvasive, non-pharmaceutical, and relatively low-cost intervention that can be implemented at infants' bedside. Thus further research is warranted to determine whether the effects noted in previous studies can be consistently replicated in diverse settings and with diverse groups of preterm infants. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Pregnancy Research on Osteopathic Manipulation Optimizing Treatment Effects: The PROMOTE Study A Randomized Controlled Trial

    PubMed Central

    HENSEL, Kendi L.; BUCHANAN, Steve; BROWN, Sarah K.; RODRIGUEZ, Mayra; CRUSER, des Anges

    2014-01-01

    Objective To evaluate the efficacy of Osteopathic Manipulative Treatment (OMT) to reduce low back pain and improve functioning during the third trimester in pregnancy and improve selected outcomes of labor and delivery. Study Design PROMOTE was a randomized, placebo-controlled trial of 400 women in their third trimester. Women were randomized to usual care only (UCO), usual care plus OMT (OMT), or usual care plus placebo ultrasound treatment (PUT). The study included seven treatments over nine weeks. The OMT protocol included specific techniques administered by board-certified OMT specialists. Outcomes were assessed using self-report measures for pain and back-related functioning, and medical records for delivery outcomes. Results There were 136 women in the OMT group, 131 in PUT, and 133 in UCO. Characteristics at baseline were similar across groups. Findings indicate significant treatment effects for pain and back related functioning (P<.001 for both), with outcomes for the OMT group similar to that of the PUT, but both groups were significantly improved compared to UCO. For secondary outcome of meconium- stained amniotic fluid there were no differences between the groups. Conclusion OMT was effective for mitigating pain and functional deterioration compared to the UCO group; however OMT did not differ significantly from PUT. This may be attributed to PUT being a more active treatment than intended. There was no higher likelihood of conversion to high risk status based on treatment group. Therefore, OMT is a safe, effective adjunctive modality to improve pain and functioning during their third trimester. PMID:25068560

  20. Few Effects of Far Transfer of Working Memory Training in ADHD: A Randomized Controlled Trial

    PubMed Central

    Egeland, Jens; Aarlien, Anne Kristine; Saunes, Brit-Kari

    2013-01-01

    Objective Studies have shown that children with ADHD profit from working memory training, although few studies have investigated transfer effects comprehensively. The current Randomized Controlled Trial analyzes transfer to other neuropsychological (NP) domains, academic performance and everyday functioning at home and school. Method Sixty-seven children with ADHD were randomized into a control group or a training group. The training group underwent Cogmed’s RoboMemo program. All participants were assessed pre-training, immediately after and eight months later with a battery of NP tests, measures of mathematical and reading skills, as well as rating scales filled out by parents and teachers. Results There was a significant training effect in psychomotor speed, but not to any other NP measures. Reading and mathematics were improved. There were no training induced changes in symptom rating scales either at home or at school. The increased reading scores remained significant eight months later. Conclusion The study is the most comprehensive study of transfer effects to date, and with mixed results compared to previous research. More research is needed regarding how to improve the training program and the conditions and thresholds for successful training. Trial Registration Controlled-Trials.com ISRCTN19133620 PMID:24124503

  1. Unexpected Effects of a System-Distributed Mobile Application in Maternity Care: A Randomized Controlled Trial.

    PubMed

    Ledford, Christy J W; Womack, Jasmyne J; Rider, Heather A; Seehusen, Angela B; Conner, Stephen J; Lauters, Rebecca A; Hodge, Joshua A

    2017-09-01

    As pregnant mothers increasingly engage in shared decision making regarding prenatal decisions, such as induction of labor, the patient's level of activation may influence pregnancy outcomes. One potential tool to increase patient activation in the clinical setting is mobile applications. However, research is limited in comparing mobile apps with other modalities of patient education and engagement tools. This study was designed to test the effectiveness of a mobile app as a replacement for a spiral notebook guide as a patient education and engagement tool in the prenatal clinical setting. This randomized controlled trial was conducted in the Women's Health Clinic and Family Health Clinic of three hospitals. Repeated-measures analysis of covariance was used to test intervention effects in the study sample of 205 patients. Mothers used a mobile app interface to more frequently record information about their pregnancy; however, across time, mothers using a mobile app reported a significant decrease in patient activation. The unexpected negative effects in the group of patients randomized to the mobile app prompt these authors to recommend that health systems pause before distributing their own version of mobile apps that may decrease patient activation. Mobile apps can be inherently empowering and engaging, but how a system encourages their use may ultimately determine their adoption and success.

  2. A preliminary double-blind, placebo-controlled randomized study of baclofen effects in alcoholic smokers

    PubMed Central

    Zywiak, William H.; Edwards, Steven M.; Tidey, Jennifer W.; Swift, Robert M.; Kenna, George A.

    2014-01-01

    Rationale There is presently no approved single treatment for dual alcohol and nicotine dependencies. Objective This pilot study investigated baclofen effects in alcoholic smokers. Methods This was a preliminary double-blind placebo-controlled randomized clinical study with 30 alcoholic smokers randomized to baclofen at 80 mg/day or placebo. A subgroup (n=18) participated in an alcohol cue-reactivity experiment. Results Baclofen, compared with placebo, significantly decreased the percent days of abstinence from alcohol-tobacco co-use (p=0.004). Alcohol dependence severity moderated baclofen effects, with the higher severity group having the greater baclofen response (p<0.001). Although the percent days of alcohol-tobacco co-use declined in both groups, this decline was greater after placebo than baclofen (p<0.001). Secondary analyses on alcohol or tobacco use alone suggested that the increase in percent days of co-abstinence was driven by the medication differences on heavy drinking days and on percent days smoking. In the cue-reactivity substudy, baclofen slightly decreased alcohol urge (p=0.058) and significantly reduced salivation (p=0.001), but these effects were not related to cue type. Conclusions This study provides preliminary evidence suggesting a possible role of baclofen in the treatment of alcoholic smokers. However, the mixed results and the small sample require larger confirmatory studies. PMID:24973894

  3. Effect of olive oil massage on weight gain in preterm infants: A randomized controlled clinical trial

    PubMed Central

    Jabraeile, Mahnaz; Rasooly, Alehe Seyyed; Farshi, Mahni Rahkar; Malakouti, Jamileh

    2016-01-01

    Background: Despite the fact that effect of massage with or without oil on the baby's weight gain is not clear, but recent studies have shown that massage with essential oils make lipid absorption through the skin. The aim of this study was to evaluate the effect of olive oil massage on weight gain in preterm infants. Materials and Methods: This study was a single-blind, randomized controlled clinical trial. In this study, infants who met inclusion criteria for the study were divided into two groups by using random numbers table. Newborns in intervention group were under massage for 10 days and 3 times for 15 min daily; the mother of these newborns had been trained already using olive oil. Moreover, the infants of the control group were under massaging without oil same as the above-mentioned method. Researchers weighed babies daily during 10 days and recorded it at the checklist. Data from the study were reviewed and analyzed by descriptive statistics and repeated measure test using the statistical software SPSS/13. Results: This study showed that the neonatal weight gain in the infants with the oil massage was 21 g daily in average, whereas the increase in infant massage without oil was 7 g. This difference was statistically significant (P < 0.001). Conclusion: Considering the positive effect of infant massage on weight gain in premature infants with olive oil, it is recommended that nurses use oil in infant massage in the neonatal units. PMID:27397955

  4. Cognitive effects of calligraphy therapy for older people: a randomized controlled trial in Hong Kong.

    PubMed

    Kwok, Timothy C Y; Bai, Xue; Kao, Henry S R; Li, Jessie C Y; Ho, Florence K Y

    2011-01-01

    This pilot study investigated the effects of calligraphy therapy on cognitive function in older Hong Kong Chinese people with mild cognitive impairment. A single-blind, randomized controlled trial was carried out in a sample of 31 adults aged 65 years or older with mild cognitive impairment. They were randomly assigned to receive either intensive calligraphy training led by a trained research assistant for eight weeks (calligraphy group, n = 14) or no calligraphy treatment (control group, n = 17). Participants' cognitive function was assessed by the Chinese version of the Mini-Mental State Examination (CMMSE) before and after calligraphy treatment. Repeated measures analysis of variance and paired samples t-tests were used to analyze the data. A significant interaction effect of time and intervention was detected [F (1, 29) = 9.11, P = 0.005, η(2) = 0.24]. The calligraphy group was found to have a prominent increase in CMMSE global score, and scores in the cognitive areas of orientation, attention, and calculation after two months (ΔM = 2.36, P < 0.01), whereas their counterparts in the control group experienced a decline in CMMSE score (ΔM = -0.41, P < 0.05). Calligraphy therapy was effective for enhancing cognitive function in older people with mild cognitive impairment and should be incorporated as part of routine programs in both community and residential care settings.

  5. Cognitive effects of calligraphy therapy for older people: a randomized controlled trial in Hong Kong

    PubMed Central

    Kwok, Timothy CY; Bai, Xue; Kao, Henry SR; Li, Jessie CY; Ho, Florence KY

    2011-01-01

    Background: This pilot study investigated the effects of calligraphy therapy on cognitive function in older Hong Kong Chinese people with mild cognitive impairment. Methods: A single-blind, randomized controlled trial was carried out in a sample of 31 adults aged 65 years or older with mild cognitive impairment. They were randomly assigned to receive either intensive calligraphy training led by a trained research assistant for eight weeks (calligraphy group, n = 14) or no calligraphy treatment (control group, n = 17). Participants’ cognitive function was assessed by the Chinese version of the Mini-Mental State Examination (CMMSE) before and after calligraphy treatment. Repeated measures analysis of variance and paired samples t-tests were used to analyze the data. Results: A significant interaction effect of time and intervention was detected [F (1, 29) = 9.11, P = 0.005, η2 = 0.24]. The calligraphy group was found to have a prominent increase in CMMSE global score, and scores in the cognitive areas of orientation, attention, and calculation after two months (ΔM = 2.36, P < 0.01), whereas their counterparts in the control group experienced a decline in CMMSE score (ΔM = −0.41, P < 0.05). Conclusion: Calligraphy therapy was effective for enhancing cognitive function in older people with mild cognitive impairment and should be incorporated as part of routine programs in both community and residential care settings. PMID:22087066

  6. A new threshold dose-response model including random effects for data from developmental toxicity studies.

    PubMed

    Hunt, Daniel L; Rai, Shesh N

    2005-01-01

    Usually, in teratological dose finding studies, there are not only threshold effects but also extra variations that cannot be accounted for by the beta-binomial model alone. The beta-binomial model assumes correlation between fetuses in the same litter. The general random effect threshold (RE) model allows the additional variability that arises due to correlation and between litter variability to be modeled, in combination with threshold in the model. The goal of this research was to investigate a threshold dose-response model with random effects (RE) to model the variability that exists between litters of animals in studies of toxic agents. Data from a developmental toxicity study of a toxic agent were analysed, using the proposed RE threshold dose-response model, which is an extension of logit in form. Also, an approximate likelihood function was used to derive parameter estimates from this model, and tests were performed to determine the significance of the model parameters, in particular, the RE parameter. A simulation study was conducted to assess the performance of the RE threshold model in estimating the model parameters. 2005 John Wiley & Sons, Ltd.

  7. Modeling of optimum light absorption in random plasmonic solar cell using effective medium theory

    NASA Astrophysics Data System (ADS)

    Piralaee, M.; Asgari, A.

    2016-12-01

    Random plasmonic nanostructures are very suitable candidates for light trapping in thin film solar cells because of their ability of efficient transportation and localization of light in a broad spectrum. In this work, besides the introducing of a novel structure of plasmonic thin-film solar cell, in which metal nanoparticles are randomly distributed through the photoactive layer of solar cell, we are presenting a new simple calculation method which can predict the behavior of plasmonic solar cells. To avoid the difficulty of analytical calculation and due to small size of constituents of the structure, we have used the effective medium theory to describe its optical properties. We have used a general description of effective dielectric function that can support each effective medium theory named spectral density theory, which takes into account the percolation of metal component and also interaction among inclusions. Using this method, the optimum values of nanoparticle's filling fraction for each wavelength within the active layer can be found where the solar cell can have the maximum absorption of light, thereupon the optimum external quantum efficiency.

  8. Effect of botulinum toxin A and nitroglycerin on random skin flap survival in rats.

    PubMed

    Ghanbarzadeh, Kourosh; Tabatabaie, Omid Reza; Salehifar, Ebrahim; Amanlou, Massoud; Khorasani, Ghasemali

    2016-01-01

    A suitable pharmacological substitute for the well-established surgical delay technique for random skin flaps to increase viability has been elusive. To evaluate the effects of nitroglycerin and botulinum toxin type A on random flap survival in a rat model. The present controlled experimental study was performed in the four groups of rats. One week after intervention in each group, the flap was raised and kept in situ, and flap necrosis was evaluated through follow-up. Group 1 received intradermal botulinum toxin type A (BTX-A) and topical nitroglycerin 2%; group 2 received BTX-A and topical Vaseline (Unilever, USA); group 3 received topical nitroglycerin and intradermal normal saline; and group 4 received topical Vaseline and intradermal normal saline. BTX-A reduced the area of necrosis compared with control (24% versus 56% respectively; P<0.001). Nitroglycerin application was associated with a trend toward improved flap viability (42% versus 56%; P=0.059). The combination of topical nitroglycerin and BTX-A, compared with Vaseline and BTX-A, was associated with decreased flap necrosis (16.1% versus 24%, respectively), although it was not statistically significant (P=0.45). BTX-A was effective in reducing distal flap necrosis. The effect of BTX-A was significantly more pronounced than nitroglycerin ointment.

  9. Effects of honey supplementation on inflammatory markers among chronic smokers: a randomized controlled trial.

    PubMed

    Ghazali, Wan Syaheedah Wan; Romli, Aminah Che; Mohamed, Mahaneem

    2017-03-28

    Honey has been demonstrated to possess anti-inflammatory property. This is a randomized, controlled, open-label trial to determine the effects of 12-week honey oral supplementation on plasma inflammatory markers such as high sensitive C-reactive protein, interleukin-6 and tumor necrosis factor-α among chronic smokers. A total of 32 non-smokers and 64 chronic smokers from Quit Smoking Clinic and Health Campus, Universiti Sains Malaysia participated in the study. Smokers were then randomized into 2 groups: smokers with honey group that received Malaysian Tualang honey (20 g/day daily for 12 weeks) and smokers without honey group. Blood was obtained from non-smokers and smokers at pre-intervention, and from smokers at post-intervention for measurement of the inflammatory markers. At pre-intervention, smokers had significantly higher high sensitive C-reactive protein than non-smokers. In smokers with honey group, tumor necrosis factor-α was significantly increased while high sensitive C-reactive protein was significantly reduced at post-intervention than at pre-intervention. This study suggests that honey supplementation has opposite effects on tumor necrosis factor-α and high sensitive C-reactive protein indicating the inconclusive effect of honey on inflammation among chronic smokers which needs further study on other inflammatory markers. The Trial has been registered in the Australian New Zealand Clinical Trials Registry: ACTRN12615001236583 . Registered 11 November 2015 (Retrospectively Registered).

  10. Effects of Interventions on Use of Hearing Protectors among Farm Operators: A Randomized Controlled Trial

    PubMed Central

    McCullagh, Marjorie C.; Banerjee, Tanima; Cohen, Michael A.; Yang, James J.

    2016-01-01

    Objective The purpose of this study was to compare the effectiveness of three interventions designed to promote hearing protector device (HPD) use. Design Randomized controlled trial. Study Sample Farm operators (n=491) were randomly assigned to one of 5 intervention groups: 1) interactive Web-based information with mailed assortment of HPDs; 2) Interactive Web-based information only; 3) static Web-based information with mailed assortment of HPDs; 4) Static Web-based information only; or 5) mailed assortment of HPDs only. Data were analyzed using a mixed model approach. Results HPD use increased among all participants, and increased more among participants receiving the mailed HPDs (with or without information) compared to participants receiving other interventions. Participants receiving the interactive Web-based information had comparable increased use of HPDs to those receiving the static Web-based information. Participants receiving the mailed HPDs had more positive situational influences scale scores than other participants. Program satisfaction was highest among mailed and Web-based information groups. Conclusions A mailed assortment of hearing protectors was more effective than information. Interactive and static information delivered via Web were similarly effective. Programs interested in increasing HPD use among farmers should consider making hearing protectors more available to farmers. PMID:26766172

  11. Examining the effect of three low-intensity pediatric obesity interventions: a pilot randomized controlled trial.

    PubMed

    Looney, Shannon M; Raynor, Hollie A

    2014-12-01

    Primary care is an ideal setting to treat pediatric obesity. Effective, low-intensity (≤25 contact hours over 6 months) interventions that reduce standardized body mass index (z-BMI) and can be delivered by primary care providers are needed. This pilot randomized controlled trial investigated the effect of 3 low-intensity (≤25 contact hours over 6 months) pediatric obesity treatments on z-BMI. Twenty-two families (children 8.0 ± 1.8 years, z-BMI of 2.34 ± 0.48) were randomized into 1 of 3, 6-month, low-intensity conditions: newsletter (N), newsletter and growth monitoring (N + GM), or newsletter and growth monitoring plus family-based behavioral counseling (N + GM + BC). Anthropometrics and child eating and leisure-time behaviors were measured. Mixed-factor analyses of variance found a significant (P < .05) main effect of time for z-BMI and servings per day of sugar sweetened beverages, with both decreasing over time. Low-intensity obesity treatments can reduce z-BMI and may be more feasible in primary care. © The Author(s) 2014.

  12. Effects of interventions on use of hearing protectors among farm operators: A randomized controlled trial.

    PubMed

    McCullagh, Marjorie C; Banerjee, Tanima; Cohen, Michael A; Yang, James J

    2016-01-01

    The purpose of this study was to compare the effectiveness of three interventions designed to promote hearing protector device (HPD) use. Randomized controlled trial. Farm operators (n = 491) were randomly assigned to one of five intervention groups: (1) interactive web-based information with mailed assortment of HPDs; (2) Interactive web-based information only; (3) static web-based information with mailed assortment of HPDs; (4) Static web-based information only; or (5) mailed assortment of HPDs only. Data were analysed using a mixed model approach. HPD use increased among all participants, and increased more among participants receiving the mailed HPDs (with or without information) compared to participants receiving other interventions. Participants receiving the interactive web-based information had comparable increased use of HPDs to those receiving the static web-based information. Participants receiving the mailed HPDs had more positive situational influences scale scores than other participants. Program satisfaction was highest among mailed and web-based information groups. A mailed assortment of hearing protectors was more effective than information. Interactive and static information delivered via web were similarly effective. Programs interested in increasing HPD use among farmers should consider making hearing protectors more available to farmers.

  13. Randomized crossover trial studying the effect of music on examination anxiety.

    PubMed

    Lai, Hui-Ling; Chen, Pin-Wen; Chen, Chia-Jung; Chang, Hui-Kuan; Peng, Tai-Chu; Chang, Fwu-Mei

    2008-11-01

    The purpose of this study was to assess the effect of lento music on examination anxiety among nursing students. A randomized crossover classroom-based trial was conducted. Thirty-eight students with a mean age of 19.4 years (SD = .54) were randomly assigned to either a music/silence or a silence/music group sequence. The students in the music group were given a 40-min group-based music intervention in a classroom, whereas the students in the silence group received the regular test without music. Using paired t-tests, there were no significant different in pretest scores for state anxiety, examination anxiety, finger temperature and pulse rate between the two conditions. Nonetheless, the findings indicated that music intervention did effectively decrease examination anxiety and state anxiety as well as reducing pulse rate and increasing higher finger temperature (p = 0.05 to 0.001). In addition, significant differences were detected between the pretest and posttest measures for silence (p = 0.001). The results suggest that lento music is effective at anxiety reduction. This study provides evidence for nursing faculty and clinical educators to foster nursing students' mastering over the anxiety of examination by using lento music.

  14. A randomized treatment-placebo study of the effectiveness of acupuncture for benign vocal pathologies.

    PubMed

    Yiu, Edwin; Xu, Jie Jie; Murry, Tom; Wei, William I; Yu, Ming; Ma, Estella; Huang, Wei; Kwong, Yee-Lan Elaine

    2006-03-01

    Acupuncture is a widely accepted treatment option for many medical ailments in China. Some reports claim that acupuncture is effective for treating dysphonia associated with benign pathological tissue changes. However, many of these reports are based on anecdotal evidence that lacks a scientific experimental design. The objective of this study was to investigate the effectiveness of intensive acupuncture therapy for dysphonias associated with benign pathological changes with a randomized, control design. Twenty-four subjects aged between 19 and 51 years were randomly assigned to either an experimental group or a placebo group. The experimental group received acupuncture on acupoints Renyin (Stomach Channel 9), Lieque (Lung Channel 7), and Zhaohai (Kidney Channel 6), which are all related to improving throat problems and vocal function, whereas the placebo group received acupuncture on acupoints Houxi (Small Intestine Channel 3) and Kunlun (Bladder Channel 60), which are not related to voicing. All subjects received 10 intensive acupuncture sessions within a 20-day period. Acoustic analysis of voice range profile, perceptual analysis of voice quality, and self-perceptions of quality-of-life (QOL) measurement by patients were the outcome measures for determining treatment efficacy. Results revealed significant improvement in the treatment group in all three aspects when compared with the placebo group. The acupuncture effect was maintained into the second week after the completion of acupuncture treatment.

  15. Biases in Estimating Treatment Effects Due to Attrition in Randomized Controlled Trials and Cluster Randomized Controlled Trials: A Simulation Study

    ERIC Educational Resources Information Center

    Dong, Nianbo; Lipsey, Mark W.

    2011-01-01

    Attrition occurs when study participants who were assigned to the treatment and control conditions do not provide outcome data and thus do not contribute to the estimation of the treatment effects. It is very common in experimental studies in education as illustrated, for instance, in a meta-analysis studying "the effects of attrition on baseline…

  16. Cost-effectiveness of interventions to prevent HIV and STDs among women: a randomized controlled trial.

    PubMed

    Ruger, Jennifer Prah; Abdallah, Arbi Ben; Ng, Nora Y; Luekens, Craig; Cottler, Linda

    2014-10-01

    Injection drug use is a leading transmission route of HIV and STDs, and disease prevention among drug users is an important public health concern. This study assesses cost-effectiveness of behavioral interventions for reducing HIV and STDs infections among injection drug-using women. Cost-effectiveness analysis was conducted from societal and provider perspectives for randomized trial data and Bernoullian model estimates of infections averted for three increasingly intensive interventions: (1) NIDA's standard intervention (SI); (2) SI plus a well woman exam (WWE); and (3) SI, WWE, plus four educational sessions (4ES). Trial results indicate that 4ES was cost-effective relative to WWE, which was dominated by SI, for most diseases. Model estimates, however, suggest that WWE was cost-effective relative to SI and dominated 4ES for all diseases. Trial and model results agree that WWE is cost-effective relative to SI per hepatitis C infection averted ($109 308 for in trial, $6 016 in model) and per gonorrhea infection averted ($9 461 in trial, $14 044 in model). In sensitivity analysis, trial results are sensitive to 5 % change in WWE effectiveness relative to SI for hepatitis C and HIV. In the model, WWE remained cost-effective or cost-saving relative to SI for HIV prevention across a range of assumptions. WWE is cost-effective relative to SI for preventing hepatitis C and gonorrhea. WWE may have similar effects as the costlier 4ES.

  17. The Effectiveness and Cost‐Effectiveness of Spinal Cord Stimulation for Refractory Angina (RASCAL Study): A Pilot Randomized Controlled Trial

    PubMed Central

    Thomson, Simon; Duarte, Rui; Brookes, Morag; deBelder, Mark; Raphael, Jon; Davies, Ed; Taylor, Rod

    2016-01-01

    Background Patients with “refractory angina” (RA) unsuitable for coronary revascularization experience high levels of hospitalization and poor health‐related quality of life. Randomized trials have shown spinal cord stimulation (SCS) to be a promising treatment for chronic stable angina and RA; however, none has compared SCS with usual care (UC). The aim of this pilot study was to address the key uncertainties of conducting a definitive multicenter trial to assess the clinical and cost‐effectiveness of SCS in RA patients, i.e., recruitment and retention of patients, burden of outcome measures, our ability to standardize UC in a UK NHS setting. Methods RA patients deemed suitable were randomized in a 1:1 ratio to SCS plus UC (SCS group) or UC alone (UC group). We sought to assess: recruitment, uptake, and retention of patients; feasibility and acceptability of SCS treatment; the feasibility and acceptability of standardizing UC; and the feasibility and acceptability of the proposed trial outcome measures. Patient outcomes were assessed at baseline (prerandomization) and three and six months postrandomization. Results We failed to meet our planned recruitment target (45 patients) and randomized 29 patients (15 SCS group, 14 UC group) over a 42‐month period across four sites. None of the study participants chose to withdraw following consent and randomization. With exception of two deaths, all completed evaluation at baseline and follow‐up. Although the study was not formally powered to compare outcomes between groups, we saw a trend toward larger improvements in both primary and secondary outcomes in the SCS group. Conclusions While patient recruitment was found to be challenging, levels of participant retention, outcome completion, and acceptability of SCS therapy were high. A number of lessons are presented in order to take forward a future definitive pragmatic randomized trial. PMID:26387883

  18. Random nanostructure scattering layer for suppression of microcavity effect and light extraction in OLEDs.

    PubMed

    Shin, Jin-Wook; Cho, Doo-Hee; Moon, Jaehyun; Joo, Chul Woong; Lee, Jonghee; Huh, Jin Woo; Park, Seung Koo; Han, Jun-Han; Cho, Nam Sung; Hwang, Joohyun; Chu, Hye Yong; Lee, Jeong-Ik

    2014-06-15

    In this study, we investigated the effect of a random nanostructure scattering layer (RSL) on the microcavity and light extraction in organic light emitting diodes (OLEDs). In the case of the conventional OLED, the optical properties change with the thickness of the hole transporting layer (HTL) because of the presence of a microcavity. However, OLEDs equipped with the an RSL showed similar values of external quantum efficiency and luminous efficacy regardless of the HTL thickness. These phenomena can be understood by the scattering effect because of the RSL, which suppresses the microcavity effect and extracts the light confined in the device. Moreover, OLEDs with the RSL led to reduced spectrum and color changes with the viewing angle.

  19. Effects of Assertiveness Training and Expressive Writing on Acculturative Stress in International Students: A Randomized Trial

    PubMed Central

    Tavakoli, Shedeh; Lumley, Mark A.; Hijazi, Alaa M.; Slavin-Spenny, Olga M.; Parris, George P.

    2010-01-01

    International university students often experience acculturative stress, and culturally appropriate techniques to manage stress are needed. This randomized trial tested the effects of group assertiveness training, private expressive writing, their combination, and a wait-list control on the acculturative stress, affect, and health of 118 international students at an urban, American university. Interventions were conducted at the start of a semester, and assessments were conducted at baseline and the end of the semester. Group assertiveness training was rated positively by students and led to lower negative affect, whereas expressive writing was less well received and led to higher homesickness and fear, but also higher positive affect. The combined intervention had no effects, perhaps because the two components negated each other. It is concluded that group assertiveness training improves emotional adjustment of international students, but expressive writing has mixed effects and needs further development and study. PMID:20357910

  20. Effects of Vaccinium Berries on Serum Lipids: A Meta-Analysis of Randomized Controlled Trials

    PubMed Central

    Zhu, Yitong; Miao, Ya; Meng, Zheying; Zhong, Yuan

    2015-01-01

    The beneficial effects of anthocyanins consumption on cardiovascular risk are supported by mechanistic and epidemiologic evidence. In order to explore the effects of Vaccinium berries rich in anthocyanins on serum lipids, we conducted a meta-analysis of relevant randomized controlled trials (RCTs). Sixteen studies with 1109 subjects were included in this meta-analysis. Significant heterogeneity confirmed differential effects between Vaccinium subclasses. The whortleberry group is significantly superior to placebo in lipids improvement. Besides, bilberry groups show significant differences in reducing LDL-C and increasing HDL-C in comparison with other treatments. For many of the other subgroups and comparison arms, there was insufficient evidence to draw conclusions about efficacy. PMID:26345230

  1. Effectiveness of papain gel in venous ulcer treatment: randomized clinical trial1

    PubMed Central

    Rodrigues, Ana Luiza Soares; de Oliveira, Beatriz Guitton Renaud Baptista; Futuro, Débora Omena; Secoli, Silvia Regina

    2015-01-01

    OBJECTIVE: to assess the effectiveness of 2% papain gel compared to 2% carboxymethyl cellulose in the treatment of chronic venous ulcer patients. METHOD: randomized controlled clinical trial with 12-week follow-up. The sample consisted of 18 volunteers and 28 venous ulcers. In the trial group, 2% papain gel was used and, in the control group, 2% carboxymethyl cellulose gel. RESULTS: the trial group showed a significant reduction in the lesion area, especially between the fifth and twelfth week of treatment, with two healed ulcers and a considerable increase in the amount of epithelial tissue in the wound bed. CONCLUSION: 2% papain gel demonstrated greater effectiveness in the reduction of the lesion area, but was similar to 2% carboxymethyl cellulose gel regarding the reduction in the amount of exudate and devitalized tissue. Multicenter research is suggested to evidence the effectiveness of 2% papain gel in the healing of venous ulcers. UTN number: U1111-1157-2998 PMID:26155004

  2. Effects of random whole-body vibration on postural control in Parkinson's disease.

    PubMed

    Turbanski, Stephan; Haas, Christian T; Schmidtbleicher, Dietmar; Friedrich, Antje; Duisberg, Petra

    2005-01-01

    We investigated spontaneous effects of random whole-body vibration (rWBV) on postural control in Parkinsonian subjects. Effects were examined in biomechanical tests from a total of 52 patients divided equally into one experimental and one control group. Postural control was tested pre- and post-treatment in two standardized conditions (narrow standing and tandem standing). The intervention was based on rWBV (ŷ: 3 mm, f: 6 Hz 1 Hz/sec) consisting of 5 series lasting 60 seconds each. The main findings from this study were that (1) rWBV can improve postural stability in Parkinson's disease (PD) spontaneously (2) these effects depend on the test condition. Based on the results of this study, rWBV can be regarded as an additional device in physical therapy in PD.

  3. Optical properties of random metal-dielectric nanocomposite films: nanoparticle size effects

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2015-09-01

    The optical properties of a semicontinuous metal film that contains randomly distributed dielectric nanoparticles are analyzed by taking into account both filling ratios and nanoparticle size effects. A new generalization of the standard Maxwell-Garnett formula for the present system is derived, by means of the linearized hydrodynamic theory in conjunction with the Poisson equation and the appropriate boundary conditions. The dispersion curves of surface modes of the system are presented and found to be strongly dependent on the volume fraction of particles as well as the particles size. The attenuated total reflection spectra due to surface modes for the case of p-polarization are plotted and the effect of varying filling factor for fixed nanoparticles size is studied, as well as the effect of varying nanoinclusions size for a fixed volume fraction of particles.

  4. Sex effects in cocaine using methadone patients randomized to contingency management interventions

    PubMed Central

    Burch, Ashley E.; Rash, Carla J.; Petry, Nancy M.

    2015-01-01

    Contingency management (CM) is an effective treatment for promoting cocaine abstinence in patients receiving methadone maintenance. However, few studies have examined the effect of sex on treatment outcomes in this population. This study evaluated the impact of sex on longest duration of abstinence (LDA) and percent negative urine samples in 323 cocaine-using methadone patients from four randomized clinical trials comparing CM to standard methadone care. Overall, women had better treatment outcomes compared to men, demonstrated by an increase in both LDA and percentages of negative samples. Patients receiving CM also had significantly higher LDA and percentages of negative samples compared to patients receiving standard care, but sex by treatment condition effects were not significant. These data suggest that cocaine using methadone patients who are women have better substance use outcomes than men in interventions that regularly monitor cocaine use, and CM is equally efficacious regardless of sex. PMID:26237326

  5. Effectiveness and Cost-Effectiveness of Different Weekly Frequencies of Pilates for Chronic Low Back Pain: Randomized Controlled Trial.

    PubMed

    Miyamoto, Gisela Cristiane; Moura, Katherinne Ferro; Franco, Yuri Rafael dos Santos; Oliveira, Naiane Teixeira Bastos de; Amaral, Diego Diulgeroglo Vicco; Branco, Amanda Nery Castelo; Silva, Maria Liliane da; Lin, Christine; Cabral, Cristina Maria Nunes

    2016-03-01

    The Pilates method has been recommended to patients with low back pain, but the evidence on effectiveness is inconclusive. In addition, there is still no evidence for the cost-effectiveness of this method or for the ideal number of sessions to achieve the highest effectiveness. The aim of this study will be to investigate the effectiveness and cost-effectiveness of the Pilates method with different weekly frequencies in the treatment of patients with nonspecific low back pain. This is a randomized controlled trial with blinded assessor. This study will be conducted at a physical therapy clinic in São Paulo, Brazil. Two hundred ninety-six patients with nonspecific low back pain between the ages of 18 and 80 years will be assessed and randomly allocated to 4 groups (n=74 patients per group). All groups will receive an educational booklet. The booklet group will not receive additional exercises. Pilates group 1 will follow a Pilates-based program once a week, Pilates group 2 will follow the same program twice a week, and Pilates group 3 will follow the same program 3 times a week. The intervention will last 6 weeks. A blinded assessor will evaluate pain, quality-adjusted life-years, general and specific disability, kinesiophobia, pain catastrophizing, and global perceived effect 6 weeks, 6 months, and 12 months after randomization. Therapists and patients will not be blinded. This will be the first study to investigate different weekly frequencies of treatment sessions for nonspecific low back pain. The results of this study will contribute to a better definition of treatment programs for this population. © 2016 American Physical Therapy Association.

  6. Effectiveness of pharmacotherapy for severe personality disorders: meta-analyses of randomized controlled trials.

    PubMed

    Ingenhoven, Theo; Lafay, Patricia; Rinne, Thomas; Passchier, Jan; Duivenvoorden, Hugo

    2010-01-01

    There has been little systematic attempt to validate current pharmacologic treatment algorithms and guidelines for severe personality disorder. We evaluated studies on the effectiveness of psychoactive drugs on specific symptom domains for borderline and/or schizotypal personality disorder. The literature was searched for placebo-controlled randomized clinical trials (PC-RCTs) on the effectiveness of psychopharmacologic drugs in personality disorder patients. The PubMed, PsychINFO, PiCarta, Cochrane, and Web of Science databases were searched using the search terms borderline personality, schizotypal personality, personality disorder, cluster A, cluster B, treatment, drug, pharmacotherapy, antipsychotic, antidepressant, mood stabilizer, effect, outcome, review, and meta-analysis for studies published between 1980 and December 2007, and references were identified from bibliographies from articles and books. Placebo-controlled randomized clinical trials on the efficacy of antipsychotics, antidepressants, and mood stabilizers regarding cognitive-perceptual symptoms, impulsive-behavioral dyscontrol, and affective dysregulation (with subdomains depressed mood, anxiety, anger, and mood lability) were selected in patients with well defined borderline and/or schizotypal personality disorder. Studies whose primary emphasis was on the treatment of Axis I disorders were excluded. Meta-analyses were conducted using 21 retrieved studies. Antipsychotics have a moderate effect on cognitive-perceptual symptoms (5 PC-RCTs; standardized mean difference [SMD]=0.56) and a moderate to large effect on anger (4 PC-RCTs; SMD=0.69). Antidepressants have no significant effect on impulsive-behavioral dyscontrol and depressed mood. They have a small but significant effect on anxiety (5 PC-RCTs; SMD=0.30) and anger (4 PC-RCTs; SMD=0.34). Mood stabilizers have a very large effect on impulsive-behavioral dyscontrol (6 PC-RCTs; SMD=1.51) and anger (7 PC-RCTs; SMD=1.33), a large effect on anxiety

  7. Effectiveness of second generation antipsychotics: A systematic review of randomized trials

    PubMed Central

    Johnsen, Erik; Jørgensen, Hugo A

    2008-01-01

    Background Systematic reviews based on efficacy trials are inconclusive about which second generation antipsychotic drug (SGA) should be preferred in normal clinical practice, and studies with longer duration and more pragmatic designs are called for. Effectiveness studies, also known as naturalistic, pragmatic, practical or real life studies, adhere to these principles as they aim to mimic daily clinical practice and have longer follow-up. Objective To review the head-to-head effectiveness of SGAs in the domains of global outcomes, symptoms of disease, and tolerability. Methods Searches were made in Embase, PubMED, and the Cochrane central register of controlled trials for effectiveness studies published from 1980 to 2008, week 1. Different combinations of the keywords antipsychotic*, neuroleptic* AND open, pragmatic, practical, naturalistic, real life, effectiveness, side effect*, unwanted effect*, tolera* AND compar* AND random* were used. Results Sixteen different reports of randomized head-to-head comparisons of SGA effectiveness were located. There were differences regarding sample sizes, inclusion criteria and follow-up periods, as well as sources of financial sponsorship. In acute-phase and first-episode patients no differences between the SGAs were disclosed regarding alleviating symptoms of disease. Olanzapine was associated with more weight gain and adverse effects on serum lipids. In the chronic phase patients olanzapine groups had longer time to discontinuation of treatment and better treatment adherence compared to other SGAs. The majority of studies found no differences between the SGAs in alleviating symptoms of psychosis in chronically ill patients. Olanzapine was associated with more metabolic adverse effects compared to the others SGAs. There were surprisingly few between-drug differences regarding side effects. First generation antipsychotics were associated with lower total mental health care costs in 2 of 3 studies on chronically ill patients

  8. Effects of dyadic planning on physical activity in couples: A randomized controlled trial.

    PubMed

    Knoll, Nina; Hohl, Diana Hilda; Keller, Jan; Schuez, Natalie; Luszczynska, Aleksandra; Burkert, Silke

    2017-01-01

    Action planning can help translate physical activity intentions into action by linking situational cues with behavioral responses. Dyadic planning extends action planning and refers to target persons forming plans for their own behavior change together with partners. This study investigated whether a dyadic planning intervention could increase physical activity in target persons and their partners, whether these effects were moderated by relationship quality and mediated by action control, activity-specific received partner support, and control. Couples (n = 338; target persons randomized) were randomly assigned to (a) a dyadic planning condition (DPC); (b) an individual planning condition (IPC), in which target persons planned and partners worked on a distractor task; or (c) a control condition (CC), in which couples worked on a distractor task. During 3 assessments up to 6 weeks postintervention, moderate (primary outcome) and vigorous activity were objectively measured; other variables were self-reported. Multilevel and path models were fit. There were no beneficial direct effects of the intervention for DPC target persons. Over time, DPC partners' vigorous activity increased, but decreased again. At lower relationship quality, DPC target persons' activity decreased, whereas IPC target persons' vigorous activity increased. Mediation hypotheses were not supported. Mutual influence models indicated positive effects of partners' on target persons' moderate activity in DPC and CC, whereas for IPC, negative effects of target persons' on partners' moderate activity emerged. Findings revealed the complexity of effects of dyadic planning on behavior change. Adding relationship quality to the equation clarified effects of DPC and IPC on physical activity. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  9. Bayesian evidence synthesis for exploring generalizability of treatment effects: a case study of combining randomized and non-randomized results in diabetes.

    PubMed

    Verde, Pablo E; Ohmann, Christian; Morbach, Stephan; Icks, Andrea

    2016-05-10

    In this paper, we present a unified modeling framework to combine aggregated data from randomized controlled trials (RCTs) with individual participant data (IPD) from observational studies. Rather than simply pooling the available evidence into an overall treatment effect, adjusted for potential confounding, the intention of this work is to explore treatment effects in specific patient populations reflected by the IPD. In this way, by collecting IPD, we can potentially gain new insights from RCTs' results, which cannot be seen using only a meta-analysis of RCTs. We present a new Bayesian hierarchical meta-regression model, which combines submodels, representing different types of data into a coherent analysis. Predictors of baseline risk are estimated from the individual data. Simultaneously, a bivariate random effects distribution of baseline risk and treatment effects is estimated from the combined individual and aggregate data. Therefore, given a subgroup of interest, the estimated treatment effect can be calculated through its correlation with baseline risk. We highlight different types of model parameters: those that are the focus of inference (e.g., treatment effect in a subgroup of patients) and those that are used to adjust for biases introduced by data collection processes (e.g., internal or external validity). The model is applied to a case study where RCTs' results, investigating efficacy in the treatment of diabetic foot problems, are extrapolated to groups of patients treated in medical routine and who were enrolled in a prospective cohort study.

  10. The effects of vasonatrin peptide on random pattern skin flap survival.

    PubMed

    Wang, Shi-Ping; Lan, Zhi-Yong; Xia, Wei; Zhao, Xi; Ma, Ge-Jia; Liu, Bei; Pan, Bao-Hua; Guo, Shu-Zhong

    2014-01-01

    A lot of methods have been intensively investigated to improve random skin flap survival. Decreasing inflammation and alleviating tissue injury have been reported to be effective in improving survival ratio. Vasonatrin peptide (VNP) is a chimera of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP). The current study demonstrates that VNP possesses the venodilating actions of CNP, the natriuretic actions of ANP, and the unique arterial vasodilating actions not associated with either ANP or CNP. However, its effects on skin flap survival have not been previously reported. Sprague-Dawley rats, weighing 220 to 260 g, were randomly divided into 2 groups, namely, the VNP-treated group and the control group. Rectangular random dorsal skin flaps measuring 3 × 9 cm including the panniculus carnosus were elevated, then the flaps were sutured into their original places. In the VNP group, 0.1 mg/kg of VNP was administered intravenously (IV) after surgery and then daily for 3 days. In the control group, 1 mL/kg of saline was administered IV after surgery and then daily for 3 days. To observe the effects of VNP, blood perfusion, histopathological examination, the inflammatory mediators (tumor necrosis factor α, interleukin 1β, and interferon γ), and biochemical analysis (malondialdehyde, glutathione, and myeloperoxidase) were detected and the flap viability was evaluated 7 days after surgery by measuring necrotic flap area and total flap area. The viability measurements showed the percentage of flap survival was increased in the VNP-treated group (76.53% ± 6.36%) as compared with the control group (61.12% ± 4.92%) (P < 0.05), and the histological and biochemical assays corroborated the data. The blood perfusion of flaps in the VNP-treated group was higher than the control group (P < 0.05). The inflammatory mediators (tumor necrosis factor α, interleukin 1β, and interferon γ) were significantly lower in the VNP-treated group than the control group (P

  11. Fitting parametric random effects models in very large data sets with application to VHA national data.

    PubMed

    Gebregziabher, Mulugeta; Egede, Leonard; Gilbert, Gregory E; Hunt, Kelly; Nietert, Paul J; Mauldin, Patrick

    2012-10-24

    With the current focus on personalized medicine, patient/subject level inference is often of key interest in translational research. As a result, random effects models (REM) are becoming popular for patient level inference. However, for very large data sets that are characterized by large sample size, it can be difficult to fit REM using commonly available statistical software such as SAS since they require inordinate amounts of computer time and memory allocations beyond what are available preventing model convergence. For example, in a retrospective cohort study of over 800,000 Veterans with type 2 diabetes with longitudinal data over 5 years, fitting REM via generalized linear mixed modeling using currently available standard procedures in SAS (e.g. PROC GLIMMIX) was very difficult and same problems exist in Stata's gllamm or R's lme packages. Thus, this study proposes and assesses the performance of a meta regression approach and makes comparison with methods based on sampling of the full data. We use both simulated and real data from a national cohort of Veterans with type 2 diabetes (n=890,394) which was created by linking multiple patient and administrative files resulting in a cohort with longitudinal data collected over 5 years. The outcome of interest was mean annual HbA1c measured over a 5 years period. Using this outcome, we compared parameter estimates from the proposed random effects meta regression (REMR) with estimates based on simple random sampling and VISN (Veterans Integrated Service Networks) based stratified sampling of the full data. Our results indicate that REMR provides parameter estimates that are less likely to be biased with tighter confidence intervals when the VISN level estimates are homogenous. When the interest is to fit REM in repeated measures data with very large sample size, REMR can be used as a good alternative. It leads to reasonable inference for both Gaussian and non-Gaussian responses if parameter estimates are

  12. Effectiveness of PELOID therapy in carpal tunnel syndrome: A randomized controlled single blind study

    NASA Astrophysics Data System (ADS)

    Metin Ökmen, Burcu; Kasapoğlu Aksoy, Meliha; Güneş, Aygül; Eröksüz, Riza; Altan, Lale

    2017-02-01

    Carpal tunnel syndrome(CTS) is the most common neuromuscular cause of upper extremity disability. We aimed to investigate the effectiveness of peloid therapy in patients with CTS. This randomized, controlled, single-blind study enrolled 70 patients between the ages of 30 to 65 who had a diagnosis of either mild, mild-to-moderate, or moderate CTS. The patients were randomized into two groups using random number table. In the first group, (Group 1)(n = 35), patients were given splint (every night for 6 weeks) + peloid treatment(five consecutive days a week for 2 weeks) and in the second group, (Group 2)(n = 28), patients received splint treatment(every night for 6 weeks) alone. The patients were assessed by using visual analog scale(VAS) for pain, electroneuromyography(ENMG), the Boston Carpal Tunnel Syndrome Questionnaire(BCTSQ), hand grip strength(HGS), finger grip strength(FGS), and Short Form-12(SF-12). The data were obtained before treatment(W0), immediately after treatment(W2), and one month after treatment(W6). Both in Group 1 and 2, there was a statistically significant improvement in all the evaluation parameters at W2 and W6 when compared to W0(p < 0.05). Comparison of the groups with each other revealed significantly better results for VAS, BCTSQ, mSNCV, SF-12 in Group 1 than in Group 2 at W2(p < 0.05). There was also a statistically significant difference in favor of Group 1 for VAS, BCTSQ, FGS and MCS at W6 when compared to W0 (p < 0.05). The results of our study demonstrated that in patients with CTS; peloid + splint treatment was more effective than splint treatment alone in pain, functionality and life quality both at after treatment(W2) and one month after treatment (W6). We may suggest peloid as a supplementary therapeutic agent in CTS.

  13. Effects of Sevoflurane Inhalation During Cardiopulmonary Bypass on Pediatric Patients: A Randomized Controlled Clinical Trial.

    PubMed

    Xiong, Hong-Yan; Liu, Yang; Shu, Duan-Chao; Zhang, Sheng-Li; Qian, Xinhong; Duan, Wei-Xun; Cheng, Liang; Yu, Shi-Qiang; Jin, Zhen-Xiao

    2016-01-01

    The effects of sevoflurane inhalation during cardiopulmonary bypass (CPB) on postoperative courses and serum cardiac troponin I (cTnI) concentrations in pediatric patients undergoing cardiac surgery have not been extensively investigated. In this single-center, prospective, randomized trial, an anesthetic regimen containing 2% sevoflurane used throughout the CPB process was compared with a total intravenous anesthesia (TIVA) regimen. One hundred and three patients undergoing congenital heart defect repair with CPB were included in this prospective randomized controlled study. They were randomized into two groups: the sevoflurane group, who received 2% sevoflurane during CPB via an oxygenator, and the control group, who received only an oxygen-air mixture. The pre- and intra-operative parameters were comparable between the two groups. There was a slight but significant increase of arterial diastolic pressure in the sevoflurane group immediately after CPB compared with control patients (46.9 ± 9.3 mm Hg vs. 43.6 ± 8.9 mm Hg; p = 0.033). There was no death in either group. The postoperative ventilation time (in mean [95% confidence interval]) was shorter in the sevoflurane group than that in the control group (26.1 [19.2, 33.0] h vs. 37.7 [24.4, 50.9] h; p = 0.014). The postoperative ICU time, hospital days, and serial serum cTnI concentrations were not significantly different between the two groups. Inhalation of 2% sevoflurane during CPB is beneficial to the recovery of pediatric patients undergoing cardiac surgery but has no significant effect on postoperative cTnI release.

  14. The effects of assertiveness training in patients with schizophrenia: a randomized, single-blind, controlled study.

    PubMed

    Lee, Tso-Ying; Chang, Shih-Chin; Chu, Hsin; Yang, Chyn-Yng; Ou, Keng-Liang; Chung, Min-Huey; Chou, Kuei-Ru

    2013-11-01

    In this study, we investigated the effects of group assertiveness training on assertiveness, social anxiety and satisfaction with interpersonal communication among patients with chronic schizophrenia. Only limited studies highlighted the effectiveness of group assertiveness training among inpatients with schizophrenia. Given the lack of group assertiveness training among patients with schizophrenia, further development of programmes focusing on facilitating assertiveness, self-confidence and social skills among inpatients with chronic schizophrenia is needed. This study used a prospective, randomized, single-blinded, parallel-group design. This study employed a prospective, randomized, parallel-group design. Seventy-four patients were randomly assigned to experimental group receiving 12 sessions of assertiveness training, or a supportive control group. Data collection took place for the period of June 2009-July 2010. Among patients with chronic schizophrenia, assertiveness, levels of social anxiety and satisfaction with interpersonal communication significantly improved immediately after the intervention and at the 3-month follow-up in the intervention group. The results of a generalized estimating equation (GEE) indicated that: (1) assertiveness significantly improved from pre- to postintervention and was maintained until the follow-up; (2) anxiety regarding social interactions significantly decreased after assertiveness training; and (3) satisfaction with interpersonal communication slightly improved after the 12-session intervention and at the 3-month follow-up. Assertivenss training is a non-invasive and inexpensive therapy that appears to improve assertiveness, social anxiety and interpersonal communication among inpatients with chronic schizophrenia. These findings may provide a reference guide to clinical nurses for developing assertiveness-training protocols. © 2013 Blackwell Publishing Ltd.

  15. Effectiveness of PELOID therapy in carpal tunnel syndrome: A randomized controlled single blind study

    NASA Astrophysics Data System (ADS)

    Metin Ökmen, Burcu; Kasapoğlu Aksoy, Meliha; Güneş, Aygül; Eröksüz, Riza; Altan, Lale

    2017-08-01

    Carpal tunnel syndrome(CTS) is the most common neuromuscular cause of upper extremity disability. We aimed to investigate the effectiveness of peloid therapy in patients with CTS. This randomized, controlled, single-blind study enrolled 70 patients between the ages of 30 to 65 who had a diagnosis of either mild, mild-to-moderate, or moderate CTS. The patients were randomized into two groups using random number table. In the first group, (Group 1)( n = 35), patients were given splint (every night for 6 weeks) + peloid treatment(five consecutive days a week for 2 weeks) and in the second group, (Group 2)( n = 28), patients received splint treatment(every night for 6 weeks) alone. The patients were assessed by using visual analog scale(VAS) for pain, electroneuromyography(ENMG), the Boston Carpal Tunnel Syndrome Questionnaire(BCTSQ), hand grip strength(HGS), finger grip strength(FGS), and Short Form-12(SF-12). The data were obtained before treatment(W0), immediately after treatment(W2), and one month after treatment(W6). Both in Group 1 and 2, there was a statistically significant improvement in all the evaluation parameters at W2 and W6 when compared to W0( p < 0.05). Comparison of the groups with each other revealed significantly better results for VAS, BCTSQ, mSNCV, SF-12 in Group 1 than in Group 2 at W2( p < 0.05). There was also a statistically significant difference in favor of Group 1 for VAS, BCTSQ, FGS and MCS at W6 when compared to W0 ( p < 0.05). The results of our study demonstrated that in patients with CTS; peloid + splint treatment was more effective than splint treatment alone in pain, functionality and life quality both at after treatment(W2) and one month after treatment (W6). We may suggest peloid as a supplementary therapeutic agent in CTS.

  16. Randomized Evaluation of the Effectiveness of a Structured Educational Program for Patients With Essential Hypertension.

    PubMed

    Perl, Sabine; Niederl, Ella; Kos, Cornelia; Mrak, Peter; Ederer, Herbert; Rakovac, Ivo; Beck, Peter; Kraler, Elisabeth; Stoff, Ingrid; Klima, Gert; Pieske, Burkert M; Pieber, Thomas R; Zweiker, Robert

    2016-07-01

    Adherence to medication and lifestyle interventions are essential keys for the management of hypertension. In this respect, a structured educational program for hypertensive patients has got remarkable merits (herz.leben). In order to determine the isolated effect of participation in the educational program, neglecting the possible impact of more intense care, this prospective multicenter randomized controlled study was designed (NCT00453037). A total of 256 patients in 13 centers were enrolled and randomly assigned to 2 groups (G). G-I (n = 137) underwent the educational program immediately (T-0), G-II (n = 119) after 6 months (T-6). Follow-up visits were done after 6 (T-6) and 12 (T-12) months. Primary endpoint was a difference in office blood pressure (BP) at T-6, when only G-I had undergone the educational program. Patients' baseline characteristics were comparable. At T-6, systolic office and home BP were significantly lower in G-I compared to G-II: office BP systolic 139 (134-150) mm Hg vs. 150 (135-165) mm Hg (P < 0.01); diastolic 80 (76-85) mm Hg vs. 84 (75-90) mm Hg (ns); home BP systolic 133 (130-140) mm Hg vs. 142 (132-150) mm Hg (P < 0.01); diastolic 80 (75-85) mm Hg vs. 80 (76-89) mm Hg (ns)). At T-12, when all patients had undergone the educational program differences in BP disappeared. The results of this multicenter randomized controlled study provide significant evidence for benefit by participation in a structured educational program. Positive effects seem to be mediated by better adherence and life style changes due to higher levels of information and patient empowerment. Therefore, educational strategies should be considered as standard of care for hypertensive patients. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Effects of diammonium glycyrrhizinate on random skin flap survival in rats: An experimental study

    PubMed Central

    Lv, Qing-Bo; Gao, Xiang; Lin, Ding-Sheng; Chen, Yun; Cao, Bin; Zhou, Kai-Liang

    2016-01-01

    Partial necrosis of skin flaps continues to restrict the survival of local skin flaps following plastic and reconstructive surgeries. The aim of the present study was to investigate the effects of diammonium glycyrrhizinate (DG), a salt of glycyrrhetinic acid that has been widely used in the therapy of chronic hepatitis and human immunodeficiency virus infection, on random skin flap survival in rats. McFarlane flaps were established in 60 male Sprague-Dawley rats randomly divided into three groups. Group I served as the control group and was injected with saline (10 mg/kg) once per day. Group II and group III were the experimental groups, and were injected with 10 mg/kg DG once and twice per day, respectively. On day 7, the survival area of the flap was measured. Tissue samples were stained with hematoxylin and eosin and immunohistochemically evaluated. Tissue edema, neutrophil density, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were evaluated. The mean survival areas of the flaps of group II were significantly larger when compared with those of group I (P<0.05), and the rats of group III exhibited significantly higher survival areas than group II (P<0.05). Histologic and immunohistochemical evaluation showed that microvessel development and the expression level of vascular endothelial growth factor were higher in the two experimental groups than in the control group. Furthermore, SOD activity was significantly increased (P<0.05), while the neutrophil density and MDA level were significantly reduced (P<0.05) in group II when compared with group I. Significant differences between group II and group III with regard to SOD activity and MDA level were also observed (P<0.05). Thus, DG may have a dose-dependent effect on promoting the survival of random skin flaps. PMID:27588181

  18. Effect of Sensory Stimuli on Restless Legs Syndrome: A Randomized Crossover Study

    PubMed Central

    Rozeman, Anouk D.; Ottolini, Truus; Grootendorst, Diana C.; Vogels, Oscar J.M.; Rijsman, Roselyne M.

    2014-01-01

    Study Objective: A variety of sensory stimuli relieve restless legs syndrome symptoms. Because systematic evaluations of sensory stimulation in restless legs syndrome are largely lacking, we performed a randomized crossover study to evaluate the effect of external sensory stimulation on restless legs syndrome symptoms. Methods: Eighteen patients underwent 3 consecutive suggestive immobilization tests with the order of the following 3 conditions randomly assigned: no electrical stimulation (condition 1), tactile and proprioceptive sensory stimulation (condition 2), and tactile sensory stimulation only (condition 3). Restless legs syndrome symptoms were quantified by visual analog scales, and periodic leg movements during wake were measured. Results: Baseline visual analogue scale score was 4.5 (range 0-60) in condition 1, 10.5 (range 0-96) in condition 2, and 8.5 in condition 3 (p = 0.21). There was a tendency towards a higher maximum visual analogue scale score and visual analogue scale score at the end of the suggested immobilization test in the conditions with tactile sensory stimulation, though not significant (p = 0.74 and p = 0.29, respectively). Fifteen patients suffered from periodic leg movements during wake. Median indices were 18 (range 0-145) in condition 1, 26 (range 0-190) in condition 2, and 49 (range 0-228) in condition 3 (p = 0.76). Conclusions: We found a tendency towards less leg discomfort in the conditions in which an external sensory input was applied. This potential benefit of sensory stimuli on restless legs syndrome severity merits further investigation as this could open new ways towards a better pathophysiological understanding and non-pharmacological treatments. Citation: Rozeman AD, Ottolini T, Grootendorst DC, Vogels OJM, Rijsman RM. Effect of sensory stimuli on restless legs syndrome: a randomized crossover study. J Clin Sleep Med 2014;10(8):893-896. PMID:25126036

  19. Randomized controlled trial of the effect of regular paracetamol on influenza infection

    PubMed Central

    Jefferies, Sarah; Walker, Steven; Weatherall, Mark; Jennings, Lance; Luck, Michelle; Barrett, Kevin; Siebers, Robert; Blackmore, Timothy; Beasley, Richard; Perrin, Kyle

    2015-01-01

    Abstract Background and objective Anti‐pyretic treatment is recommended in the management of influenza infection. In animal models anti‐pyretic treatment increases mortality from influenza. We investigated the effects of paracetamol on viral and clinical outcomes in adults with influenza infection. Methods This is a randomized, double‐blind, placebo‐controlled trial of adults aged 18–65 years with influenza‐like illness and positive influenza rapid antigen test. Treatments were 1 g paracetamol four times a day, or matching placebo, for 5 days. Pernasal swabs were taken for influenza quantitative RT‐PCR at Baseline and Days 1, 2 and 5. Temperature and symptom scores were recorded for 5–14 days or time of resolution respectively. The primary outcome variable was area under the curve (AUC) for quantitative PCR log10 viral load from Baseline to Day 5. Results A total of 80 participants were randomized: no one was lost to follow up, and one withdrew after 4 days. There were 22 and 24 participants who were influenza PCR‐positive in placebo and in paracetamol groups respectively. Mean (SD) AUC PCR log10 viral load was 4.40 (0.91) in placebo and 4.64 (0.88) in paracetamol; difference was −0.24, 95% CI: −0.78 to 0.29, P = 0.36. In all participants there were no differences in symptom scores, temperature, time to resolution of illness and health status, with no interaction between randomized treatment and whether influenza was detected by PCR. Conclusion Regular paracetamol had no effect on viral shedding, temperature or clinical symptoms in patients with PCR‐confirmed influenza. There remains an insufficient evidence base for paracetamol use in influenza infection. Clinical trial registration: ACTRN12611000497909 at the Australian New Zealand Clinical Trials Registry. PMID:26638130

  20. Assessment of effectiveness of smoking cessation intervention among male prisoners in India: A randomized controlled trial

    PubMed Central

    Naik, Sachin; Khanagar, Sanjeev; Kumar, Amit; Ramachandra, Sujith; Vadavadagi, Sunil V.; Dhananjaya, Kiran Murthy

    2014-01-01

    Background: Tobacco smoking is an integral part of prison life and an established part of the culture. Little attention has been paid to prevention of smoking in prison. Approximately 70–80% of prisoners have been identified as current smokers. Aim: To assess the effectiveness of smoking cessation intervention among male prisoners at Central Jail, Bangalore city. Aim: To assess the effectiveness of smoking cessation intervention among male prisoners at Central Jail, Bangalore city. Materials and Methods: A randomized controlled trial was planned among male prisoners in Central Jail, Bangalore city. There were 1600 convicted prisoners. A self-administered questionnaire was given to the prisoners to assess their smoking behavior by which prevalence of tobacco smoking was found. Exactly 1352 tobacco users were studied. Among them, there were 1252 smokers. Based on inclusion criteria and informed consent given by the prisoners, a sample of 600 was chosen for the study by systematic random sampling. Among the 600 prisoners, 300 were randomly selected for the study group and 300 for the control group. Results: Prevalence of tobacco smoking among the prisoners was 92.60%. In the present study, after smoking cessation intervention, 17% showed no change in smoking, 21.66% reduced smoking, 16% stopped smoking, and 45.33% relapsed (P < 0.0001) at the end of 6-month follow-up in the study group. Conclusion: Tobacco use was high among the prisoners. Tobacco reduction is possible in the prison even if the living conditions are not favorable. Relatively high rate of relapse in our study indicates that some policies should be adopted to improve smokers’ information on consequences of tobacco on health and motivational intervention should be added to prisoners. PMID:25558450

  1. Personal health records: a randomized trial of effects on elder medication safety.

    PubMed

    Chrischilles, Elizabeth A; Hourcade, Juan Pablo; Doucette, William; Eichmann, David; Gryzlak, Brian; Lorentzen, Ryan; Wright, Kara; Letuchy, Elena; Mueller, Michael; Farris, Karen; Levy, Barcey

    2014-01-01

    To examine the impact of a personal health record (PHR) on medication-use safety among older adults. Online PHRs have potential as tools to manage health information. We know little about how to make PHRs accessible for older adults and what effects this will have. A PHR was designed and pretested with older adults and tested in a 6-month randomized controlled trial. After completing mailed baseline questionnaires, eligible computer users aged 65 and over were randomized 3:1 to be given access to a PHR (n=802) or serve as a standard care control group (n=273). Follow-up questionnaires measured change from baseline medication use, medication reconciliation behaviors, and medication management problems. Older adults were interested in keeping track of their health and medication information. A majority (55.2%) logged into the PHR and used it, but only 16.1% used it frequently. At follow-up, those randomized to the PHR group were significantly less likely to use multiple non-steroidal anti-inflammatory drugs-the most common warning generated by the system (viewed by 23% of participants). Compared with low/non-users, high users reported significantly more changes in medication use and improved medication reconciliation behaviors, and recognized significantly more side effects, but there was no difference in use of inappropriate medications or adherence measures. PHRs can engage older adults for better medication self-management; however, features that motivate continued use will be needed. Longer-term studies of continued users will be required to evaluate the impact of these changes in behavior on patient health outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  2. The effect of exercise on sleep and fatigue in rheumatoid arthritis: a randomized controlled study.

    PubMed

    Durcan, Laura; Wilson, Fiona; Cunnane, Gaye

    2014-10-01

    Sleep disturbance and chronic fatigue are common in rheumatoid arthritis (RA) and contribute to disability, symptomatology, and healthcare use. It has long been recognized in other populations that exercise can improve sleep and diminish fatigue. The effect of exercise on sleep quality and fatigue in RA has not been evaluated. Ours is a randomized controlled study in RA to determine the effect of an exercise program on sleep quality and fatigue. These were measured using the Pittsburgh Sleep Quality Index and the Fatigue Severity Scale. Patients were randomized to either a 12-week, home-based exercise intervention or usual care. The exercise program consisted of specific exercises to target individual deficiencies identified using the Health Assessment Questionnaire (HAQ) with cardiovascular work as per the guidelines. The intervention group was evaluated on a 3-week basis. Full evaluation was carried out at baseline and at 12 weeks. Forty patients were randomized to the intervention with 38 controls. In the exercise intervention group, there was a statistically significant improvement in HAQ (p = 0.00), pain (p = 0.05), stiffness (p = 0.05), sleep quality (p = 0.04), and fatigue (p = 0.04). In our control group, there was a statistically significant improvement demonstrated in their overall perceptions of the benefits of exercise, but none of the other variables. Our study demonstrates that an exercise program resulted in significant improvement in sleep quality and fatigue. This is particularly interesting given the importance of fatigue as an outcome measure in RA and gives us yet another reason to prescribe exercise in this population.

  3. Handwashing with soap or alcoholic solutions? A randomized clinical trial of its effectiveness.

    PubMed

    Zaragoza, M; Sallés, M; Gomez, J; Bayas, J M; Trilla, A

    1999-06-01

    The effectiveness of an alcoholic solution compared with the standard hygienic handwashing procedure during regular work in clinical wards and intensive care units of a large public university hospital in Barcelona was assessed. A prospective, randomized clinical trial with crossover design, paired data, and blind evaluation was done. Eligible health care workers (HCWs) included permanent and temporary HCWs of wards and intensive care units. From each category, a random sample of persons was selected. HCWs were randomly assigned to regular handwashing (liquid soap and water) or handwashing with the alcoholic solution by using a crossover design. The number of colony-forming units on agar plates from hands printing in 3 different samples was counted. A total of 47 HCWs were included. The average reduction in the number of colony-forming units from samples before handwashing to samples after handwashing was 49.6% for soap and water and 88.2% for the alcoholic solution. When both methods were compared, the average number of colony-forming units recovered after the procedure showed a statistically significant difference in favor of the alcoholic solution (P <.001). The alcoholic solution was well tolerated by HCWs. Overall acceptance rate was classified as "good" by 72% of HCWs after 2 weeks use. Of all HCWs included, 9.3% stated that the use of the alcoholic solution worsened minor pre-existing skin conditions. Although the regular use of hygienic soap and water handwashing procedures is the gold standard, the use of alcoholic solutions is effective and safe and deserves more attention, especially in situations in which the handwashing compliance rate is hampered by architectural problems (lack of sinks) or nursing work overload.

  4. The effects of random bottom bathymetry on coherence in shallow water acoustic propagation

    NASA Astrophysics Data System (ADS)

    Wylie, Jennifer Leigh

    In an ideal shallow water propagation channel the sound field is accurately described by normal modes and the mode structure is predictable with clean separated modes. However the real ocean environment is rarely ideal, and variations in bottom bathymetry and water column sound speed are usually present. Random fluctuations of the sound speed in time, space, and/or the boundaries can distort modes such that phase coherence is reduced and under some conditions completely lost. The basic research community seeks to understand the effects of internal waves on temporal coherence. Here the study method of choice is to use fixed system experiments that observe both oceanographic and acoustical fluctuations. On the other hand applied Naval research is focused on using mobile platforms to instantaneously measure spatial coherence shipboard, and they have little to no interest in measuring long term coherence. Here we seek to present a unified theory using normal modes. Both spatial and temporal coherence as well as the effects of source motion and Doppler will be addressed. Mode structure can be randomized in two ways: sound speed fluctuations and boundary variations. The research proposed here will emphasize spatial variations of the bottom bathymetry and how they affect mode arrivals. A parabolic equation model is used to predict mode shapes in a range dependent environment and random variations in bottom boundaries will be introduced and distortion in the mode arrival structure will be observed. The mode arrival structures will then be used to estimate temporal and spatial coherence of the mode arrivals and the predictions will be compared to the data from three different shallow water experiments.

  5. The effect of magnesium supplements on early post-transplantation glucose metabolism: a randomized controlled trial.

    PubMed

    Van Laecke, Steven; Nagler, Evi Vanessa; Taes, Youri; Van Biesen, Wim; Peeters, Patrick; Vanholder, Raymond

    2014-09-01

    Post-transplantation hypomagnesemia is common and predicts diabetes. Magnesium improves glycemic control in diabetics and insulin sensitivity in insulin resistant subjects. We aimed to assess the effectiveness of oral magnesium for improving glycemic control and insulin sensitivity at 3 months post-transplantation. We conducted a single-center, open-label, randomized parallel group study. We included adults with serum magnesium <1.7 mg/dl within 2 weeks after kidney transplantation. We randomized participants to 450 mg magnesium oxide up to three times daily or no treatment. The primary endpoint was the mean difference in fasting glycemia. Secondary endpoints were the mean difference in area under the curve (AUC) of glucose during an oral glucose tolerance test and insulin resistance measured by Homeostasis Model of Assessment-Insulin Resistance (HOMA-IR). Analyses were on intention-to-treat basis. In patients randomized to magnesium oxide (N = 27) versus no treatment (N = 27), fasting glycemia on average was 11.5 mg/dl lower (95% CI 1.7 to 21.3; P = 0.02). There was no difference between the two groups neither for 2 h AUC, where the mean value was 1164 mg/dl/min (95% CI -1884 to 4284; P = 0.45) lower in the treatment group nor for HOMA-IR. Magnesium supplements modestly improved fasting glycemia without effect on insulin resistance. Higher baseline glycemia among patients in the control group may have driven the positive outcome (ClinicalTrials.gov number: NCT01889576).

  6. Effects of structured patient education in adults with atopic dermatitis: Multicenter randomized controlled trial.

    PubMed

    Heratizadeh, Annice; Werfel, Thomas; Wollenberg, Andreas; Abraham, Susanne; Plank-Habibi, Sibylle; Schnopp, Christina; Sticherling, Michael; Apfelbacher, Christian; Biedermann, Tilo; Breuer, Kristine; Fell, Isabel; Fölster-Holst, Regina; Heine, Guido; Grimm, Jennifer; Hennighausen, Lars; Kugler, Claudia; Reese, Imke; Ring, Johannes; Schäkel, Knut; Schmitt, Jochen; Seikowski, Kurt; von Stebut, Esther; Wagner, Nicola; Waßmann-Otto, Anja; Wienke-Graul, Ute; Weisshaar, Elke; Worm, Margitta; Gieler, Uwe; Kupfer, Joerg

    2017-09-01

    Atopic dermatitis (AD) is a chronic relapsing skin disease prevalent in 1% to 3% of adults in Western industrialized countries. We sought to investigate the effectiveness of educational training in an outpatient setting on coping with the disease, quality of life, symptoms, and severity in adults with AD. In this German prospective, randomized controlled multicenter study, adult patients with moderate-to-severe AD were educated by referring to a comprehensive 12-hour training manual consented by a multiprofessional study group from different centers (Arbeitsgemeinschaft Neurodermitisschulung für Erwachsene [ARNE]). Patients were randomly allocated to the intervention or waiting control groups. Study visits were performed at baseline and after 1 year (1 year of follow-up). Primary outcomes were defined as a decrease in (1) "catastrophizing cognitions" with respect to itching (Juckreiz-Kognitions-Fragebogen questionnaire), (2) "social anxiety" (Marburger Hautfragebogen questionnaire), (3) subjective burden by symptoms of the disease (Skindex-29 questionnaire), and (4) improvement of disease signs and symptoms assessed by using the SCORAD index at 1 year of follow-up. Data were analyzed on an intention-to-treat basis. At 1 year of follow-up, patients from the intervention group (n = 168) showed a significantly better improvement compared with the waiting group (n = 147) in the following defined primary study outcomes: coping behavior with respect to itching (P < .001), quality of life assessed by using the Skindex-29 questionnaire (P < .001), and the SCORAD index (P < .001). This is the first randomized, controlled multicenter study on patient education in adult AD. The ARNE training program shows significant beneficial effects on a variety of psychosocial parameters, as well as AD severity. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  7. Exploring the question-behaviour effect: randomized controlled trial of motivational and question-behaviour interventions.

    PubMed

    Ayres, Karen; Conner, Mark; Prestwich, Andrew; Hurling, Robert; Cobain, Mark; Lawton, Rebecca; O'Connor, Daryl B

    2013-02-01

    Measuring intentions and other cognitions to perform a behaviour can promote performance of that behaviour (the question-behaviour effect, QBE). It has been suggested that this effect may be amplified for individuals motivated to perform the behaviour. The present research tested the efficacy of combining a motivational intervention (providing personal risk information) with measuring intentions and other cognitions in a fully crossed 2 × 2 design with an objective measure of behaviour in an at-risk population using a randomized controlled trial (RCT). Participants with elevated serum cholesterol levels were randomized to one of four conditions: a combined group receiving both a motivational intervention (personalized cardiovascular disease risk information) and a QBE manipulation (completing a questionnaire about diet), one group receiving a motivational intervention, one group receiving a QBE intervention, or one group receiving neither. All participants subsequently had the opportunity to obtain a personalized health plan linked to reducing personal risk for coronary heart disease. Neither the motivational nor the QBE manipulations alone significantly increased rates of obtaining the health plan. However, the interaction between conditions was significant. Decomposition of the interaction indicated that the combined condition (motivational plus QBE manipulation) produced significantly higher rates of obtaining the health plan (96.2%) compared to the other three groups combined (80.3%). The findings provide insights into the mechanism underlying the QBE and suggest the importance of motivation to perform the behaviour in observing the effect. What is already known on this subject? Research has indicated that merely asking questions about a behaviour may be sufficient to produce changes in that or related behaviours (referred to as the question-behaviour effect; QBE). Previous studies have suggested that the QBE may be moderated by the individual's motivation to

  8. Influences of anterior capsule polishing on effective lens position after cataract surgery: a randomized controlled trial

    PubMed Central

    Gao, Yang; Dang, Guang-Fu; Wang, Xu; Duan, Lian; Wu, Xin-Yi

    2015-01-01

    To evaluate the effects of anterior capsule polishing on effective lens position (ELP) and the actual axial movements of IOLs by measuring the anterior chamber depth (ACD). This prospective randomized double-blind controlled clinical trial included patients who underwent bilateral uneventful cataract surgeries and were implanted the same IOLs (SN60WF). Extensive polishing was performed randomly in the anterior capsule of one eye with Whitman Shepherd double-ended capsule polisher, and the opposite unpolished capsule was used as the control. The ACD was measured 1 day, 1 week, 1 month, 3 months and 6 months after surgery with the anterior segment optical coherence tomography (AS-OCT). The actual axial movement of IOL was defined as the root mean square (RMS) of the change in ELP at each visit. A total of 40 eyes of 20 patients were included, and 10 patients (50%) were men. All the patients underwent uneventful surgeries without intraoperative or postoperative complications, and returned on time for measurements. The mean age of them was 70.5±7.6 years (range 56 to 79 years). No significant differences were observed between the mean ELP of the control group and the polished group (P>0.05). Nevertheless, the ELPRMS of the polished group was significantly smaller than that of the control group (P=0.005). Polishing anterior capsule intraoperatively improved the axial position stability of the IOL in the long term. PMID:26550324

  9. Effects of acupressure on progress of labor and cesarean section rate: randomized clinical trial

    PubMed Central

    Mafetoni, Reginaldo Roque; Shimo, Antonieta Keiko Kakuda

    2015-01-01

    OBJECTIVE To analyze the effects of acupressure at the SP6 point on labor duration and cesarean section rates in parturients served in a public maternity hospital. METHODS This controlled, randomized, double-blind, pragmatic clinical trial involved 156 participants with gestational age ≥ 37 weeks, cervical dilation ≥ 4 cm, and ≥ 2 contractions in 10 min. The women were randomly divided into an acupressure, placebo, or control group at a university hospital in an inland city in the state of Sao Paulo, Brazil, in 2013. Acupressure was applied to the SP6 point during contractions for 20 min. RESULTS The average labor duration was significantly different between the SP6 acupressure group [221.5 min (SD = 162.4)] versus placebo [397.9 min (SD = 265.6)] and versus control [381.9 min (SD = 358.3)] (p = 0.0047); however, the groups were similar regarding the cesarean section rates (p = 0.2526) and Apgar scores in the first minute (p = 0.9542) and the fifth minute (p = 0.7218) of life of the neonate. CONCLUSIONS The SP6 acupressure point proved to be a complementary measure to induce labor and may shorten the labor duration without causing adverse effects to the mother or the newborn. However, it did not affect the cesarean section rate. PMID:25741644

  10. Crash Frequency Analysis Using Hurdle Models with Random Effects Considering Short-Term Panel Data.

    PubMed

    Chen, Feng; Ma, Xiaoxiang; Chen, Suren; Yang, Lin

    2016-10-26

    Random effect panel data hurdle models are established to research the daily crash frequency on a mountainous section of highway I-70 in Colorado. Road Weather Information System (RWIS) real-time traffic and weather and road surface conditions are merged into the models incorporating road characteristics. The random effect hurdle negative binomial (REHNB) model is developed to study the daily crash frequency along with three other competing models. The proposed model considers the serial correlation of observations, the unbalanced panel-data structure, and dominating zeroes. Based on several statistical tests, the REHNB model is identified as the most appropriate one among four candidate models for a typical mountainous highway. The results show that: (1) the presence of over-dispersion in the short-term crash frequency data is due to both excess zeros and unobserved heterogeneity in the crash data; and (2) the REHNB model is suitable for this type of data. Moreover, time-varying variables including weather conditions, road surface conditions and traffic conditions are found to play importation roles in crash frequency. Besides the methodological advancements, the proposed technology bears great potential for engineering applications to develop short-term crash frequency models by utilizing detailed data from field monitoring data such as RWIS, which is becoming more accessible around the world.

  11. Effectiveness of jaw relaxation for burn dressing pain: randomized clinical trial.

    PubMed

    Rafii, Forough; Mohammadi-Fakhar, Fahimeh; Jamshidi Orak, Roohangiz

    2014-12-01

    Patients hospitalized for burn injuries experience severe pain, both immediately after the injury and during daily therapeutic procedures such as dressing changes. Relaxation is increasingly suggested as a pain control technique that can be used by nurses in daily practice. Yet the effects of relaxation on burn pain are not clear. The aim of this study was to investigate whether jaw relaxation will decrease pain intensity of burn dressing. Accordingly, a randomized clinical trial (n = 100) was conducted between 2009 and 2010 to compare jaw relaxation and usual care. Consenting patients were randomly assigned to either experimental or control groups using minimization. The experimental group practiced jaw relaxation for 20 minutes before entering the dressing room. Data were collected by visual analog scale (VAS), and several structured questions were asked of the experimental group. No significant difference was seen between mean pain intensity scores in the experimental and control groups after dressing (p = .676). Regarding the ineffectiveness of jaw relaxation for pain intensity of burn dressing, future studies are suggested to concentrate on longer durations of relaxation time and continuing the procedure in dressing room. Simultaneous study of the effect of this technique on residual, breakthrough, and procedural burn pain is also recommended. Copyright © 2014 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.

  12. Effectiveness of oncogenetics training on general practitioners' consultation skills: a randomized controlled trial

    PubMed Central

    Houwink, Elisa J.F.; Muijtjens, Arno M.M.; van Teeffelen, Sarah R.; Henneman, Lidewij; Rethans, Jan Joost; van der Jagt, Liesbeth E.J.; van Luijk, Scheltus J.; Dinant, Geert Jan; van der Vleuten, Cees; Cornel, Martina C.

    2014-01-01

    Purpose: General practitioners are increasingly called upon to deliver genetic services and could play a key role in translating potentially life-saving advancements in oncogenetic technologies to patient care. If general practitioners are to make an effective contribution in this area, their genetics competencies need to be upgraded. The aim of this study was to investigate whether oncogenetics training for general practitioners improves their genetic consultation skills. Methods: In this pragmatic, blinded, randomized controlled trial, the intervention consisted of a 4-h training (December 2011 and April 2012), covering oncogenetic consultation skills (family history, familial risk assessment, and efficient referral), attitude (medical ethical issues), and clinical knowledge required in primary-care consultations. Outcomes were measured using observation checklists by unannounced standardized patients and self-reported questionnaires. Results: Of 88 randomized general practitioners who initially agreed to participate, 56 completed all measurements. Key consultation skills significantly and substantially improved; regression coefficients after intervention were equivalent to 0.34 and 0.28 at 3-month follow-up, indicating a moderate effect size. Satisfaction and perceived applicability of newly learned skills were highly scored. Conclusion: The general practitioner–specific training proved to be a feasible, satisfactory, and clinically applicable method to improve oncogenetics consultation skills and could be used as an educational framework to inform future training activities with the ultimate aim of improving medical care. PMID:23722870

  13. A general joint model for longitudinal measurements and competing risks survival data with heterogeneous random effects

    PubMed Central

    Li, Gang; Elashoff, Robert M.; Pan, Jianxin

    2011-01-01

    This article studies a general joint model for longitudinal measurements and competing risks survival data. The model consists of a linear mixed effects sub-model for the longitudinal outcome, a proportional cause-specific hazards frailty sub-model for the competing risks survival data, and a regression sub-model for the variance–covariance matrix of the multivariate latent random effects based on a modified Cholesky decomposition. The model provides a useful approach to adjust for non-ignorable missing data due to dropout for the longitudinal outcome, enables analysis of the survival outcome with informative censoring and intermittently measured time-dependent covariates, as well as joint analysis of the longitudinal and survival outcomes. Unlike previously studied joint models, our model allows for heterogeneous random covariance matrices. It also offers a framework to assess the homogeneous covariance assumption of existing joint models. A Bayesian MCMC procedure is developed for parameter estimation and inference. Its performances and frequentist properties are investigated using simulations. A real data example is used to illustrate the usefulness of the approach. PMID:20549344

  14. Crash Frequency Analysis Using Hurdle Models with Random Effects Considering Short-Term Panel Data

    PubMed Central

    Chen, Feng; Ma, Xiaoxiang; Chen, Suren; Yang, Lin

    2016-01-01

    Random effect panel data hurdle models are established to research the daily crash frequency on a mountainous section of highway I-70 in Colorado. Road Weather Information System (RWIS) real-time traffic and weather and road surface conditions are merged into the models incorporating road characteristics. The random effect hurdle negative binomial (REHNB) model is developed to study the daily crash frequency along with three other competing models. The proposed model considers the serial correlation of observations, the unbalanced panel-data structure, and dominating zeroes. Based on several statistical tests, the REHNB model is identified as the most appropriate one among four candidate models for a typical mountainous highway. The results show that: (1) the presence of over-dispersion in the short-term crash frequency data is due to both excess zeros and unobserved heterogeneity in the crash data; and (2) the REHNB model is suitable for this type of data. Moreover, time-varying variables including weather conditions, road surface conditions and traffic conditions are found to play importation roles in crash frequency. Besides the methodological advancements, the proposed technology bears great potential for engineering applications to develop short-term crash frequency models by utilizing detailed data from field monitoring data such as RWIS, which is becoming more accessible around the world. PMID:27792209

  15. Does Cox analysis of a randomized survival study yield a causal treatment effect?

    PubMed

    Aalen, Odd O; Cook, Richard J; Røysland, Kjetil

    2015-10-01

    Statistical methods for survival analysis play a central role in the assessment of treatment effects in randomized clinical trials in cardiovascular disease, cancer, and many other fields. The most common approach to analysis involves fitting a Cox regression model including a treatment indicator, and basing inference on the large sample properties of the regression coefficient estimator. Despite the fact that treatment assignment is randomized, the hazard ratio is not a quantity which admits a causal interpretation in the case of unmodelled heterogeneity. This problem arises because the risk sets beyond the first event time are comprised of the subset of individuals who have not previously failed. The balance in the distribution of potential confounders between treatment arms is lost by this implicit conditioning, whether or not censoring is present. Thus while the Cox model may be used as a basis for valid tests of the null hypotheses of no treatment effect if robust variance estimates are used, modeling frameworks more compatible with causal reasoning may be preferrable in general for estimation.

  16. Anxiety sensitivity risk reduction in smokers: A randomized control trial examining effects on panic

    PubMed Central

    Schmidt, Norman B.; Raines, Amanda M.; Allan, Nicholas P.; Zvolensky, Michael J.

    2016-01-01

    Empirical evidence has identified several risk factors for panic psychopathology, including smoking and anxiety sensitivity (AS; the fear of anxiety-related sensations). Smokers with elevated AS are therefore a particularly vulnerable population for panic. Yet, there is little knowledge about how to reduce risk of panic among high AS smokers. The present study prospectively evaluated panic outcomes within the context of a controlled randomized risk reduction program for smokers. Participants (N = 526) included current smokers who all received a state-of-the-art smoking cessation intervention with approximately half randomized to the AS reduction intervention termed Panic-smoking Program (PSP). The primary hypotheses focus on examining the effects of a PSP on panic symptoms in the context of this vulnerable population. Consistent with prediction, there was a significant effect of treatment condition on AS, such that individuals in the PSP condition, compared to those in the control condition, demonstrated greater decreases in AS throughout treatment and the follow-up period. In addition, PSP treatment resulted in lower rates of panic-related symptomatology. Moreover, mediation analyses indicated that reductions in AS resulted in lower panic symptoms. The present study provides the first empirical evidence that brief, targeted psychoeducational interventions can mitigate panic risk among smokers. PMID:26752327

  17. Anxiety sensitivity risk reduction in smokers: A randomized control trial examining effects on panic.

    PubMed

    Schmidt, Norman B; Raines, Amanda M; Allan, Nicholas P; Zvolensky, Michael J

    2016-02-01

    Empirical evidence has identified several risk factors for panic psychopathology, including smoking and anxiety sensitivity (AS; the fear of anxiety-related sensations). Smokers with elevated AS are therefore a particularly vulnerable population for panic. Yet, there is little knowledge about how to reduce risk of panic among high AS smokers. The present study prospectively evaluated panic outcomes within the context of a controlled randomized risk reduction program for smokers. Participants (N = 526) included current smokers who all received a state-of-the-art smoking cessation intervention with approximately half randomized to the AS reduction intervention termed Panic-smoking Program (PSP). The primary hypotheses focus on examining the effects of a PSP on panic symptoms in the context of this vulnerable population. Consistent with prediction, there was a significant effect of treatment condition on AS, such that individuals in the PSP condition, compared to those in the control condition, demonstrated greater decreases in AS throughout treatment and the follow-up period. In addition, PSP treatment resulted in lower rates of panic-related symptomatology. Moreover, mediation analyses indicated that reductions in AS resulted in lower panic symptoms. The present study provides the first empirical evidence that brief, targeted psychoeducational interventions can mitigate panic risk among smokers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Network sampling coverage II: The effect of non-random missing data on network measurement.

    PubMed

    Smith, Jeffrey A; Moody, James; Morgan, Jonathan

    2017-01-01

    Missing data is an important, but often ignored, aspect of a network study. Measurement validity is affected by missing data, but the level of bias can be difficult to gauge. Here, we describe the effect of missing data on network measurement across widely different circumstances. In Part I of this study (Smith and Moody, 2013), we explored the effect of measurement bias due to randomly missing nodes. Here, we drop the assumption that data are missing at random: what happens to estimates of key network statistics when central nodes are more/less likely to be missing? We answer this question using a wide range of empirical networks and network measures. We find that bias is worse when more central nodes are missing. With respect to network measures, Bonacich centrality is highly sensitive to the loss of central nodes, while closeness centrality is not; distance and bicomponent size are more affected than triad summary measures and behavioral homophily is more robust than degree-homophily. With respect to types of networks, larger, directed networks tend to be more robust, but the relation is weak. We end the paper with a practical application, showing how researchers can use our results (translated into a publically available java application) to gauge the bias in their own data.

  19. Generalized essential energy space random walks to more effectively accelerate solute sampling in aqueous environment.

    PubMed

    Lv, Chao; Zheng, Lianqing; Yang, Wei

    2012-01-28

    Molecular dynamics sampling can be enhanced via the promoting of potential energy fluctuations, for instance, based on a Hamiltonian modified with the addition of a potential-energy-dependent biasing term. To overcome the diffusion sampling issue, which reveals the fact that enlargement of event-irrelevant energy fluctuations may abolish sampling efficiency, the essential energy space random walk (EESRW) approach was proposed earlier. To more effectively accelerate the sampling of solute conformations in aqueous environment, in the current work, we generalized the EESRW method to a two-dimension-EESRW (2D-EESRW) strategy. Specifically, the essential internal energy component of a focused region and the essential interaction energy component between the focused region and the environmental region are employed to define the two-dimensional essential energy space. This proposal is motivated by the general observation that in different conformational events, the two essential energy components have distinctive interplays. Model studies on the alanine dipeptide and the aspartate-arginine peptide demonstrate sampling improvement over the original one-dimension-EESRW strategy; with the same biasing level, the present generalization allows more effective acceleration of the sampling of conformational transitions in aqueous solution. The 2D-EESRW generalization is readily extended to higher dimension schemes and employed in more advanced enhanced-sampling schemes, such as the recent orthogonal space random walk method. © 2012 American Institute of Physics

  20. Effects of acupressure on progress of labor and cesarean section rate: randomized clinical trial.

    PubMed

    Mafetoni, Reginaldo Roque; Shimo, Antonieta Keiko Kakuda

    2015-01-01

    OBJECTIVE To analyze the effects of acupressure at the SP6 point on labor duration and cesarean section rates in parturients served in a public maternity hospital. METHODS This controlled, randomized, double-blind, pragmatic clinical trial involved 156 participants with gestational age ≥ 37 weeks, cervical dilation ≥ 4 cm, and ≥ 2 contractions in 10 min. The women were randomly divided into an acupressure, placebo, or control group at a university hospital in an inland city in the state of Sao Paulo, Brazil, in 2013. Acupressure was applied to the SP6 point during contractions for 20 min. RESULTS The average labor duration was significantly different between the SP6 acupressure group [221.5 min (SD = 162.4)] versus placebo [397.9 min (SD = 265.6)] and versus control [381.9 min (SD = 358.3)] (p = 0.0047); however, the groups were similar regarding the cesarean section rates (p = 0.2526) and Apgar scores in the first minute (p = 0.9542) and the fifth minute (p = 0.7218) of life of the neonate. CONCLUSIONS The SP6 acupressure point proved to be a complementary measure to induce labor and may shorten the labor duration without causing adverse effects to the mother or the newborn. However, it did not affect the cesarean section rate.