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Sample records for hierarchical linear growth

  1. Using hierarchical linear growth models to evaluate protective mechanisms that mediate science achievement

    Science.gov (United States)

    von Secker, Clare Elaine

    The study of students at risk is a major topic of science education policy and discussion. Much research has focused on describing conditions and problems associated with the statistical risk of low science achievement among individuals who are members of groups characterized by problems such as poverty and social disadvantage. But outcomes attributed to these factors do not explain the nature and extent of mechanisms that account for differences in performance among individuals at risk. There is ample theoretical and empirical evidence that demographic differences should be conceptualized as social contexts, or collections of variables, that alter the psychological significance and social demands of life events, and affect subsequent relationships between risk and resilience. The hierarchical linear growth models used in this dissertation provide greater specification of the role of social context and the protective effects of attitude, expectations, parenting practices, peer influences, and learning opportunities on science achievement. While the individual influences of these protective factors on science achievement were small, their cumulative effect was substantial. Meta-analysis conducted on the effects associated with psychological and environmental processes that mediate risk mechanisms in sixteen social contexts revealed twenty-two significant differences between groups of students. Positive attitudes, high expectations, and more intense science course-taking had positive effects on achievement of all students, although these factors were not equally protective in all social contexts. In general, effects associated with authoritative parenting and peer influences were negative, regardless of social context. An evaluation comparing the performance and stability of hierarchical linear growth models with traditional repeated measures models is included as well.

  2. Hierarchical linear modeling of FIM instrument growth curve characteristics after spinal cord injury.

    Science.gov (United States)

    Warschausky, S; Kay, J B; Kewman, D G

    2001-03-01

    To examine the recovery of aspects of functional independence as a continuous process using growth curve analysis. Retrospective database review of functional outcome assessment data from inception cohort. Inpatient rehabilitation unit; community. A total of 142 subjects (79.6% men; age range, 18-77yr; mean age +/- standard deviation, 36.2 +/- 15.5yr) who were admitted to a rehabilitation unit between March 1986 and November 1994 with a minimum of 4 postinjury FIM assessments. Neurologic subgroups included 63 individuals with paraplegia, 36 with low tetraplegia, 24 with high tetraplegia, and 19 with incomplete injury. FIM instrument. Growth curve analyses with hierarchical linear modeling using a decelerating recovery function yielded a reliable model in which longer rehabilitation length of stay was associated with a more rapid rate of recovery but lower plateau. Neurologic injury category had expected effects on rate and degree of recovery. Level of impairment-specific results included an age effect in which older age was associated with lower level of plateau. In specific neurologic groups there was a significant gender effect, in which men made more rapid recovery than women, and a significant effect of level of education, in which higher education was associated with more rapid rate of recovery. Rate of FIM recovery was reliably modeled in the sample with incomplete injuries, but none of the demographic predictors was significant. Functional recovery can be modeled as a decelerating rather than simple linear function. The study of predictors of recovery characteristics, including rate of recovery and plateau, offers a valuable way of understanding rehabilitative needs and outcomes. Gender and education effects on the recovery process are intriguing and warrant further investigation.

  3. Application of piecewise hierarchical linear growth modeling to the study of continuity in behavioral development of baboons (Papio hamadryas).

    Science.gov (United States)

    Hernández-Lloreda, María Victoria; Colmenares, Fernando; Martínez-Arias, Rosario

    2004-09-01

    In behavioral science, developmental discontinuities are thought to arise when the association between an outcome measure and the underlying process changes over time. Sudden changes in behavior across time are often taken to indicate that a reorganization in the outcome-process relationship may have occurred. The authors proposed in this article the use of piecewise hierarchical linear growth modeling as a statistical methodology to search for discontinuities in behavioral development and illustrated its possibilities by applying 2-piece hierarchical linear models to the study of developmental trajectories of baboon (Papio hamadryas) mothers' behavior during their infants' 1st year of life. The authors provided empirical evidence that piecewise growth modeling can be used to determine whether abrupt changes in development trajectories are tied to changes in the underlying process. ((c) 2004 APA, all rights reserved).

  4. Hierarchical Linear Modeling (HLM): An Introduction to Key Concepts within Cross-Sectional and Growth Modeling Frameworks. Technical Report #1308

    Science.gov (United States)

    Anderson, Daniel

    2012-01-01

    This manuscript provides an overview of hierarchical linear modeling (HLM), as part of a series of papers covering topics relevant to consumers of educational research. HLM is tremendously flexible, allowing researchers to specify relations across multiple "levels" of the educational system (e.g., students, classrooms, schools, etc.).…

  5. Multicollinearity in hierarchical linear models.

    Science.gov (United States)

    Yu, Han; Jiang, Shanhe; Land, Kenneth C

    2015-09-01

    This study investigates an ill-posed problem (multicollinearity) in Hierarchical Linear Models from both the data and the model perspectives. We propose an intuitive, effective approach to diagnosing the presence of multicollinearity and its remedies in this class of models. A simulation study demonstrates the impacts of multicollinearity on coefficient estimates, associated standard errors, and variance components at various levels of multicollinearity for finite sample sizes typical in social science studies. We further investigate the role multicollinearity plays at each level for estimation of coefficient parameters in terms of shrinkage. Based on these analyses, we recommend a top-down method for assessing multicollinearity in HLMs that first examines the contextual predictors (Level-2 in a two-level model) and then the individual predictors (Level-1) and uses the results for data collection, research problem redefinition, model re-specification, variable selection and estimation of a final model.

  6. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    CERN Document Server

    Jelonek, M

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of modeling hierarchical linear equations and estimation based on MPlus software. I present my own model to illustrate the impact of different factors on school acceptation level.

  7. Modeling hierarchical structures - Hierarchical Linear Modeling using MPlus

    OpenAIRE

    Jelonek, Magdalena

    2006-01-01

    The aim of this paper is to present the technique (and its linkage with physics) of overcoming problems connected to modeling social structures, which are typically hierarchical. Hierarchical Linear Models provide a conceptual and statistical mechanism for drawing conclusions regarding the influence of phenomena at different levels of analysis. In the social sciences it is used to analyze many problems such as educational, organizational or market dilemma. This paper introduces the logic of m...

  8. When to Use Hierarchical Linear Modeling

    National Research Council Canada - National Science Library

    Veronika Huta

    2014-01-01

    Previous publications on hierarchical linear modeling (HLM) have provided guidance on how to perform the analysis, yet there is relatively little information on two questions that arise even before analysis...

  9. An introduction to hierarchical linear modeling

    National Research Council Canada - National Science Library

    Woltman, Heather; Feldstain, Andrea; MacKay, J. Christine; Rocchi, Meredith

    2012-01-01

    This tutorial aims to introduce Hierarchical Linear Modeling (HLM). A simple explanation of HLM is provided that describes when to use this statistical technique and identifies key factors to consider before conducting this analysis...

  10. Managing Clustered Data Using Hierarchical Linear Modeling

    Science.gov (United States)

    Warne, Russell T.; Li, Yan; McKyer, E. Lisako J.; Condie, Rachel; Diep, Cassandra S.; Murano, Peter S.

    2012-01-01

    Researchers in nutrition research often use cluster or multistage sampling to gather participants for their studies. These sampling methods often produce violations of the assumption of data independence that most traditional statistics share. Hierarchical linear modeling is a statistical method that can overcome violations of the independence…

  11. Managing Clustered Data Using Hierarchical Linear Modeling

    Science.gov (United States)

    Warne, Russell T.; Li, Yan; McKyer, E. Lisako J.; Condie, Rachel; Diep, Cassandra S.; Murano, Peter S.

    2012-01-01

    Researchers in nutrition research often use cluster or multistage sampling to gather participants for their studies. These sampling methods often produce violations of the assumption of data independence that most traditional statistics share. Hierarchical linear modeling is a statistical method that can overcome violations of the independence…

  12. Hierarchical linear regression models for conditional quantiles

    Institute of Scientific and Technical Information of China (English)

    TIAN Maozai; CHEN Gemai

    2006-01-01

    The quantile regression has several useful features and therefore is gradually developing into a comprehensive approach to the statistical analysis of linear and nonlinear response models,but it cannot deal effectively with the data with a hierarchical structure.In practice,the existence of such data hierarchies is neither accidental nor ignorable,it is a common phenomenon.To ignore this hierarchical data structure risks overlooking the importance of group effects,and may also render many of the traditional statistical analysis techniques used for studying data relationships invalid.On the other hand,the hierarchical models take a hierarchical data structure into account and have also many applications in statistics,ranging from overdispersion to constructing min-max estimators.However,the hierarchical models are virtually the mean regression,therefore,they cannot be used to characterize the entire conditional distribution of a dependent variable given high-dimensional covariates.Furthermore,the estimated coefficient vector (marginal effects)is sensitive to an outlier observation on the dependent variable.In this article,a new approach,which is based on the Gauss-Seidel iteration and taking a full advantage of the quantile regression and hierarchical models,is developed.On the theoretical front,we also consider the asymptotic properties of the new method,obtaining the simple conditions for an n1/2-convergence and an asymptotic normality.We also illustrate the use of the technique with the real educational data which is hierarchical and how the results can be explained.

  13. Understanding the mathematics and science achievement and growth trajectories of high ability high school students using hierarchical linear modeling

    Science.gov (United States)

    Belen-Ferrer, Bellasanta

    2009-12-01

    This study used longitudinal data and individual, family, and academic-related matriculation variables to examine trends in initial status and growth trajectories in overall academics, mathematics, and science achievement among 224 high ability high school Asian students. Results indicate that females have an advantage in both initial status and growth rates in overall academics and science. None of the family variables entered in the models were found to be significantly related to overall academics grade point average. All available matriculation variables entered into the models explained less than or at most about half the variance in initial achievement status and growth rate in overall academics and science but not in mathematics. These results strongly imply that other factors, notably family and school and/or classroom-related variables, not measured by the ones used in the models could explain the expected variance in initial status and growth rate of the students especially in Mathematics.

  14. An introduction to hierarchical linear modeling

    Directory of Open Access Journals (Sweden)

    Heather Woltman

    2012-02-01

    Full Text Available This tutorial aims to introduce Hierarchical Linear Modeling (HLM. A simple explanation of HLM is provided that describes when to use this statistical technique and identifies key factors to consider before conducting this analysis. The first section of the tutorial defines HLM, clarifies its purpose, and states its advantages. The second section explains the mathematical theory, equations, and conditions underlying HLM. HLM hypothesis testing is performed in the third section. Finally, the fourth section provides a practical example of running HLM, with which readers can follow along. Throughout this tutorial, emphasis is placed on providing a straightforward overview of the basic principles of HLM.

  15. When to Use Hierarchical Linear Modeling

    Directory of Open Access Journals (Sweden)

    Veronika Huta

    2014-04-01

    Full Text Available Previous publications on hierarchical linear modeling (HLM have provided guidance on how to perform the analysis, yet there is relatively little information on two questions that arise even before analysis: Does HLM apply to one’s data and research question? And if it does apply, how does one choose between HLM and other methods sometimes used in these circumstances, including multiple regression, repeated-measures or mixed ANOVA, and structural equation modeling or path analysis? The purpose of this tutorial is to briefly introduce HLM and then to review some of the considerations that are helpful in answering these questions, including the nature of the data, the model to be tested, and the information desired on the output. Some examples of how the same analysis could be performed in HLM, repeated-measures or mixed ANOVA, and structural equation modeling or path analysis are also provided. .

  16. Fast, Linear Time Hierarchical Clustering using the Baire Metric

    CERN Document Server

    Contreras, Pedro

    2011-01-01

    The Baire metric induces an ultrametric on a dataset and is of linear computational complexity, contrasted with the standard quadratic time agglomerative hierarchical clustering algorithm. In this work we evaluate empirically this new approach to hierarchical clustering. We compare hierarchical clustering based on the Baire metric with (i) agglomerative hierarchical clustering, in terms of algorithm properties; (ii) generalized ultrametrics, in terms of definition; and (iii) fast clustering through k-means partititioning, in terms of quality of results. For the latter, we carry out an in depth astronomical study. We apply the Baire distance to spectrometric and photometric redshifts from the Sloan Digital Sky Survey using, in this work, about half a million astronomical objects. We want to know how well the (more costly to determine) spectrometric redshifts can predict the (more easily obtained) photometric redshifts, i.e. we seek to regress the spectrometric on the photometric redshifts, and we use clusterwi...

  17. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  18. Building Algebra Testlets: A Comparison of Hierarchical and Linear Structures.

    Science.gov (United States)

    Wainer, Howard; And Others

    1991-01-01

    Hierarchical (adaptive) and linear methods of testlet construction were compared. The performance of 2,080 ninth and tenth graders on a 4-item testlet was used to predict performance on the entire test. The adaptive test was slightly superior as a predictor, but the cost of obtaining that superiority was considerable. (SLD)

  19. A hierarchical linear model for tree height prediction.

    Science.gov (United States)

    Vicente J. Monleon

    2003-01-01

    Measuring tree height is a time-consuming process. Often, tree diameter is measured and height is estimated from a published regression model. Trees used to develop these models are clustered into stands, but this structure is ignored and independence is assumed. In this study, hierarchical linear models that account explicitly for the clustered structure of the data...

  20. Augmenting Visual Analysis in Single-Case Research with Hierarchical Linear Modeling

    Science.gov (United States)

    Davis, Dawn H.; Gagne, Phill; Fredrick, Laura D.; Alberto, Paul A.; Waugh, Rebecca E.; Haardorfer, Regine

    2013-01-01

    The purpose of this article is to demonstrate how hierarchical linear modeling (HLM) can be used to enhance visual analysis of single-case research (SCR) designs. First, the authors demonstrated the use of growth modeling via HLM to augment visual analysis of a sophisticated single-case study. Data were used from a delayed multiple baseline…

  1. Thirteen years after. Using hierarchical linear modeling to investigate long-term assessment center validity

    OpenAIRE

    Jansen, P.G.W.

    2003-01-01

    Using hierarchical linear modeling the author investigated temporal trends in the predictive validity of an assessment center for career advancement (measured as salary growth) over a 13-year period, for a sample of 456 academic graduates. Using year of entry and tenure as controls, linear and quadratic properties of individual salary curves could be predicted by the assessment center dimensions. The validity of the (clinical) overall assessment rating for persons with tenure of at least 12 y...

  2. Hierarchical Gompertzian growth maps with application in astrophysics

    CERN Document Server

    De Martino, S

    2010-01-01

    The Gompertz model describes the growth in time of the size of significant quantities associated to a large number of systems, taking into account nonlinearity features by a linear equation satisfied by a nonlinear function of the size. Following this scheme, we introduce a class of hierarchical maps which describe discrete sequences of intermediate characteristic scales. We find the general solutions of the maps, which account for a rich set of possible phenomena. Eventually, we provide an important application, by showing that a map belonging to the class so introduced generates all the observed astrophysical length and mass scales.

  3. Impact of hierarchical memory systems on linear algebra algorithm design

    Energy Technology Data Exchange (ETDEWEB)

    Gallivan, K.; Jalby, W.; Meier, U.; Sameh, A.H.

    1988-01-01

    Linear algebra algorithms based on the BLAS or extended BLAS do not achieve high performance on multivector processors with a hierarchical memory system because of a lack of data locality. For such machines, block linear algebra algorithms must be implemented in terms of matrix-matrix primitives (BLAS3). Designing efficient linear algebra algorithms for these architectures requires analysis of the behavior of the matrix-matrix primitives and the resulting block algorithms as a function of certain system parameters. The analysis must identify the limits of performance improvement possible via blocking and any contradictory trends that require trade-off consideration. The authors propose a methodology that facilitates such an analysis and use it to analyze the performance of the BLAS3 primitives used in block methods. A similar analysis of the block size-performance relationship is also performed at the algorithm level for block versions of the LU decomposition and the Gram-Schmidt orthogonalization procedures.

  4. Hierarchical Non-linear Image Registration Integrating Deformable Segmentation

    Institute of Scientific and Technical Information of China (English)

    RAN Xin; QI Fei-hu

    2005-01-01

    A hierarchical non-linear method for image registration was presented, which integrates image segmentation and registration under a variational framework. An improved deformable model is used to simultaneously segment and register feature from multiple images. The objects in the image pair are segmented by evolving a single contour and meanwhile the parameters of affine registration transformation are found out. After that, a contour-constrained elastic registration is applied to register the images correctly. The experimental results indicate that the proposed approach is effective to segment and register medical images.

  5. Dietary arginine and linear growth

    DEFF Research Database (Denmark)

    van Vught, Anneke J A H; Dagnelie, Pieter C; Arts, Ilja C W

    2013-01-01

    The amino acid arginine is a well-known growth hormone (GH) stimulator and GH is an important modulator of linear growth. The aim of the present study was to investigate the effect of dietary arginine on growth velocity in children between 7 and 13 years of age. Data from the Copenhagen School...

  6. Finite Population Correction for Two-Level Hierarchical Linear Models.

    Science.gov (United States)

    Lai, Mark H C; Kwok, Oi-Man; Hsiao, Yu-Yu; Cao, Qian

    2017-03-16

    The research literature has paid little attention to the issue of finite population at a higher level in hierarchical linear modeling. In this article, we propose a method to obtain finite-population-adjusted standard errors of Level-1 and Level-2 fixed effects in 2-level hierarchical linear models. When the finite population at Level-2 is incorrectly assumed as being infinite, the standard errors of the fixed effects are overestimated, resulting in lower statistical power and wider confidence intervals. The impact of ignoring finite population correction is illustrated by using both a real data example and a simulation study with a random intercept model and a random slope model. Simulation results indicated that the bias in the unadjusted fixed-effect standard errors was substantial when the Level-2 sample size exceeded 10% of the Level-2 population size; the bias increased with a larger intraclass correlation, a larger number of clusters, and a larger average cluster size. We also found that the proposed adjustment produced unbiased standard errors, particularly when the number of clusters was at least 30 and the average cluster size was at least 10. We encourage researchers to consider the characteristics of the target population for their studies and adjust for finite population when appropriate. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  7. Modeling local item dependence with the hierarchical generalized linear model.

    Science.gov (United States)

    Jiao, Hong; Wang, Shudong; Kamata, Akihito

    2005-01-01

    Local item dependence (LID) can emerge when the test items are nested within common stimuli or item groups. This study proposes a three-level hierarchical generalized linear model (HGLM) to model LID when LID is due to such contextual effects. The proposed three-level HGLM was examined by analyzing simulated data sets and was compared with the Rasch-equivalent two-level HGLM that ignores such a nested structure of test items. The results demonstrated that the proposed model could capture LID and estimate its magnitude. Also, the two-level HGLM resulted in larger mean absolute differences between the true and the estimated item difficulties than those from the proposed three-level HGLM. Furthermore, it was demonstrated that the proposed three-level HGLM estimated the ability distribution variance unaffected by the LID magnitude, while the two-level HGLM with no LID consideration increasingly underestimated the ability variance as the LID magnitude increased.

  8. Hierarchical and Non-Hierarchical Linear and Non-Linear Clustering Methods to “Shakespeare Authorship Question”

    Directory of Open Access Journals (Sweden)

    Refat Aljumily

    2015-09-01

    Full Text Available A few literary scholars have long claimed that Shakespeare did not write some of his best plays (history plays and tragedies and proposed at one time or another various suspect authorship candidates. Most modern-day scholars of Shakespeare have rejected this claim, arguing that strong evidence that Shakespeare wrote the plays and poems being his name appears on them as the author. This has caused and led to an ongoing scholarly academic debate for quite some long time. Stylometry is a fast-growing field often used to attribute authorship to anonymous or disputed texts. Stylometric attempts to resolve this literary puzzle have raised interesting questions over the past few years. The following paper contributes to “the Shakespeare authorship question” by using a mathematically-based methodology to examine the hypothesis that Shakespeare wrote all the disputed plays traditionally attributed to him. More specifically, the mathematically based methodology used here is based on Mean Proximity, as a linear hierarchical clustering method, and on Principal Components Analysis, as a non-hierarchical linear clustering method. It is also based, for the first time in the domain, on Self-Organizing Map U-Matrix and Voronoi Map, as non-linear clustering methods to cover the possibility that our data contains significant non-linearities. Vector Space Model (VSM is used to convert texts into vectors in a high dimensional space. The aim of which is to compare the degrees of similarity within and between limited samples of text (the disputed plays. The various works and plays assumed to have been written by Shakespeare and possible authors notably, Sir Francis Bacon, Christopher Marlowe, John Fletcher, and Thomas Kyd, where “similarity” is defined in terms of correlation/distance coefficient measure based on the frequency of usage profiles of function words, word bi-grams, and character triple-grams. The claim that Shakespeare authored all the disputed

  9. A note on adding and deleting edges in hierarchical log-linear models

    DEFF Research Database (Denmark)

    Edwards, David

    2012-01-01

    The operations of edge addition and deletion for hierarchical log-linear models are defined, and polynomial-time algorithms for the operations are given......The operations of edge addition and deletion for hierarchical log-linear models are defined, and polynomial-time algorithms for the operations are given...

  10. Predictability of extremes in non-linear hierarchically organized systems

    Science.gov (United States)

    Kossobokov, V. G.; Soloviev, A.

    2011-12-01

    Understanding the complexity of non-linear dynamics of hierarchically organized systems progresses to new approaches in assessing hazard and risk of the extreme catastrophic events. In particular, a series of interrelated step-by-step studies of seismic process along with its non-stationary though self-organized behaviors, has led already to reproducible intermediate-term middle-range earthquake forecast/prediction technique that has passed control in forward real-time applications during the last two decades. The observed seismic dynamics prior to and after many mega, great, major, and strong earthquakes demonstrate common features of predictability and diverse behavior in course durable phase transitions in complex hierarchical non-linear system of blocks-and-faults of the Earth lithosphere. The confirmed fractal nature of earthquakes and their distribution in space and time implies that many traditional estimations of seismic hazard (from term-less to short-term ones) are usually based on erroneous assumptions of easy tractable analytical models, which leads to widespread practice of their deceptive application. The consequences of underestimation of seismic hazard propagate non-linearly into inflicted underestimation of risk and, eventually, into unexpected societal losses due to earthquakes and associated phenomena (i.e., collapse of buildings, landslides, tsunamis, liquefaction, etc.). The studies aimed at forecast/prediction of extreme events (interpreted as critical transitions) in geophysical and socio-economical systems include: (i) large earthquakes in geophysical systems of the lithosphere blocks-and-faults, (ii) starts and ends of economic recessions, (iii) episodes of a sharp increase in the unemployment rate, (iv) surge of the homicides in socio-economic systems. These studies are based on a heuristic search of phenomena preceding critical transitions and application of methodologies of pattern recognition of infrequent events. Any study of rare

  11. On the unnecessary ubiquity of hierarchical linear modeling.

    Science.gov (United States)

    McNeish, Daniel; Stapleton, Laura M; Silverman, Rebecca D

    2017-03-01

    In psychology and the behavioral sciences generally, the use of the hierarchical linear model (HLM) and its extensions for discrete outcomes are popular methods for modeling clustered data. HLM and its discrete outcome extensions, however, are certainly not the only methods available to model clustered data. Although other methods exist and are widely implemented in other disciplines, it seems that psychologists have yet to consider these methods in substantive studies. This article compares and contrasts HLM with alternative methods including generalized estimating equations and cluster-robust standard errors. These alternative methods do not model random effects and thus make a smaller number of assumptions and are interpreted identically to single-level methods with the benefit that estimates are adjusted to reflect clustering of observations. Situations where these alternative methods may be advantageous are discussed including research questions where random effects are and are not required, when random effects can change the interpretation of regression coefficients, challenges of modeling with random effects with discrete outcomes, and examples of published psychology articles that use HLM that may have benefitted from using alternative methods. Illustrative examples are provided and discussed to demonstrate the advantages of the alternative methods and also when HLM would be the preferred method. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  12. Investigating follow-up outcome change using hierarchical linear modeling.

    Science.gov (United States)

    Ogrodniczuk, J S; Piper, W E; Joyce, A S

    2001-03-01

    Individual change in outcome during a one-year follow-up period for 98 patients who received either interpretive or supportive psychotherapy was examined using hierarchical linear modeling (HLM). This followed a previous study that had investigated average (treatment condition) change during follow-up using traditional methods of data analysis (repeated measures ANOVA, chi-square tests). We also investigated whether two patient personality characteristics-quality of object relations (QOR) and psychological mindedness (PM)-predicted individual change. HLM procedures yielded findings that were not detected using traditional methods of data analysis. New findings indicated that the rate of individual change in outcome during follow-up varied significantly among the patients. QOR was directly related to favorable individual change for supportive therapy patients, but not for patients who received interpretive therapy. The findings have implications for determining which patients will show long-term benefit following short-term supportive therapy and how to enhance it. The study also found significant associations between QOR and final outcome level.

  13. Scale of association: hierarchical linear models and the measurement of ecological systems

    Science.gov (United States)

    Sean M. McMahon; Jeffrey M. Diez

    2007-01-01

    A fundamental challenge to understanding patterns in ecological systems lies in employing methods that can analyse, test and draw inference from measured associations between variables across scales. Hierarchical linear models (HLM) use advanced estimation algorithms to measure regression relationships and variance-covariance parameters in hierarchically structured...

  14. Nonresident Undergraduates' Performance in English Writing Classes-Hierarchical Linear Modeling Analysis

    National Research Council Canada - National Science Library

    Allison A Vaughn; Matthew Bergman; Barry Fass-Holmes

    2015-01-01

    ...) in the fall term of the five most recent academic years. Hierarchical linear modeling analyses showed that the predictors with the largest effect sizes were English writing programs and class level...

  15. LIMO EEG: a toolbox for hierarchical LInear MOdeling of ElectroEncephaloGraphic data

    National Research Council Canada - National Science Library

    Pernet, Cyril R; Chauveau, Nicolas; Gaspar, Carl; Rousselet, Guillaume A

    2011-01-01

    ...). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data...

  16. LIMO EEG: A Toolbox for Hierarchical LInear MOdeling of ElectroEncephaloGraphic Data

    National Research Council Canada - National Science Library

    Pernet, Cyril R; Chauveau, Nicolas; Gaspar, Carl; Rousselet, Guillaume A

    2011-01-01

    ...). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data...

  17. Black Hole Growth in Hierarchical Galaxy Formation

    CERN Document Server

    Malbon, R K; Frenk, C S; Lacey, C G; Malbon, Rowena K.

    2006-01-01

    We incorporate a model for black hole growth during galaxy mergers into the semi-analytical galaxy formation model based on Lambda-CDM proposed by Baugh et al. (2005). Our black hole model has one free parameter, which we set by matching the observed zeropoint of the local correlation between black hole mass and bulge luminosity. We present predictions for the evolution with redshift of the relationships between black hole mass and bulge properties. Our simulations reproduce the evolution of the optical luminosity function of quasars. We study the demographics of the black hole population and address the issue of how black holes acquire their mass. We find that the direct accretion of cold gas during starbursts is an important growth mechanism for lower mass black holes and at high redshift. On the other hand, the re-assembly of pre-existing black hole mass into larger units via merging dominates the growth of more massive black holes at low redshift. This prediction could be tested by future gravitational wa...

  18. Growth Mechanism of Pumpkin-Shaped Vaterite Hierarchical Structures

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2015-03-01

    CaCO3-based biominerals possess sophisticated hierarchical structures and promising mechanical properties. Recent researches imply that vaterite may play an important role in formation of CaCO3-based biominerals. However, as a less common polymorph of CaCO3, the growth mechanism of vaterite remains not very clear. Here we report the growth of a pumpkin-shaped vaterite hierarchical structure with a six-fold symmetrical axis and lamellar microstructure. We demonstrate that the growth is controlled by supersaturation and the intrinsic crystallographic anisotropy of vaterite. For the scenario of high supersaturation, the nucleation rate is higher than the lateral extension rate, favoring the ``double-leaf'' spherulitic growth. Meanwhile, nucleation occurs preferentially in as determined by the crystalline structure of vaterite, modulating the grown products with a hexagonal symmetry. The results are beneficial for an in-depth understanding of the biomineralization of CaCO3. The growth mechanism may also be applicable to interpret the formation of similar hierarchical structures of other materials. The authors gratefully acknowledge the financial support from National Science Foundation of China (Grant Nos. 51172104 and 50972057) and National Key Basic Research Program of China (Grant No. 2010CB630705).

  19. Item Response Theory Using Hierarchical Generalized Linear Models

    Directory of Open Access Journals (Sweden)

    Hamdollah Ravand

    2015-03-01

    Full Text Available Multilevel models (MLMs are flexible in that they can be employed to obtain item and person parameters, test for differential item functioning (DIF and capture both local item and person dependence. Papers on the MLM analysis of item response data have focused mostly on theoretical issues where applications have been add-ons to simulation studies with a methodological focus. Although the methodological direction was necessary as a first step to show how MLMs can be utilized and extended to model item response data, the emphasis needs to be shifted towards providing evidence on how applications of MLMs in educational testing can provide the benefits that have been promised. The present study uses foreign language reading comprehension data to illustrate application of hierarchical generalized models to estimate person and item parameters, differential item functioning (DIF, and local person dependence in a three-level model.

  20. Classification errors in contingency tables analyzed with hierarchical log-linear models. Technical report No. 20

    Energy Technology Data Exchange (ETDEWEB)

    Korn, E L

    1978-08-01

    This thesis is concerned with the effect of classification error on contingency tables being analyzed with hierarchical log-linear models (independence in an I x J table is a particular hierarchical log-linear model). Hierarchical log-linear models provide a concise way of describing independence and partial independences between the different dimensions of a contingency table. The structure of classification errors on contingency tables that will be used throughout is defined. This structure is a generalization of Bross' model, but here attention is paid to the different possible ways a contingency table can be sampled. Hierarchical log-linear models and the effect of misclassification on them are described. Some models, such as independence in an I x J table, are preserved by misclassification, i.e., the presence of classification error will not change the fact that a specific table belongs to that model. Other models are not preserved by misclassification; this implies that the usual tests to see if a sampled table belong to that model will not be of the right significance level. A simple criterion will be given to determine which hierarchical log-linear models are preserved by misclassification. Maximum likelihood theory is used to perform log-linear model analysis in the presence of known misclassification probabilities. It will be shown that the Pitman asymptotic power of tests between different hierarchical log-linear models is reduced because of the misclassification. A general expression will be given for the increase in sample size necessary to compensate for this loss of power and some specific cases will be examined.

  1. Hierarchical linear model: thinking outside the traditional repeated-measures analysis-of-variance box.

    Science.gov (United States)

    Lininger, Monica; Spybrook, Jessaca; Cheatham, Christopher C

    2015-04-01

    Longitudinal designs are common in the field of athletic training. For example, in the Journal of Athletic Training from 2005 through 2010, authors of 52 of the 218 original research articles used longitudinal designs. In 50 of the 52 studies, a repeated-measures analysis of variance was used to analyze the data. A possible alternative to this approach is the hierarchical linear model, which has been readily accepted in other medical fields. In this short report, we demonstrate the use of the hierarchical linear model for analyzing data from a longitudinal study in athletic training. We discuss the relevant hypotheses, model assumptions, analysis procedures, and output from the HLM 7.0 software. We also examine the advantages and disadvantages of using the hierarchical linear model with repeated measures and repeated-measures analysis of variance for longitudinal data.

  2. Hierarchical Linear Model: Thinking Outside the Traditional Repeated-Measures Analysis-of-Variance Box

    Science.gov (United States)

    Lininger, Monica; Spybrook, Jessaca; Cheatham, Christopher C.

    2015-01-01

    Longitudinal designs are common in the field of athletic training. For example, in the Journal of Athletic Training from 2005 through 2010, authors of 52 of the 218 original research articles used longitudinal designs. In 50 of the 52 studies, a repeated-measures analysis of variance was used to analyze the data. A possible alternative to this approach is the hierarchical linear model, which has been readily accepted in other medical fields. In this short report, we demonstrate the use of the hierarchical linear model for analyzing data from a longitudinal study in athletic training. We discuss the relevant hypotheses, model assumptions, analysis procedures, and output from the HLM 7.0 software. We also examine the advantages and disadvantages of using the hierarchical linear model with repeated measures and repeated-measures analysis of variance for longitudinal data. PMID:25875072

  3. Liquid phase epitaxial growth of heterostructured hierarchical MOF thin films

    KAUST Repository

    Chernikova, Valeriya

    2017-05-10

    Precise control of epitaxial growth of MOF-on-MOF thin films, for ordered hierarchical tbo-type structures is demonstrated. The heterostructured MOF thin film was fabricated by successful sequential deposition of layers from two different MOFs. The 2-periodic layers, edge-transitive 4,4-square lattices regarded as supermolecular building layers, were commendably cross-linked using a combination of inorganic/organic and organic pillars.

  4. Predicting longitudinal change in language production and comprehension in individuals with Down syndrome: hierarchical linear modeling.

    Science.gov (United States)

    Chapman, Robin S; Hesketh, Linda J; Kistler, Doris J

    2002-10-01

    Longitudinal change in syntax comprehension and production skill, measured four times across a 6-year period, was modeled in 31 individuals with Down syndrome who were between the ages of 5 and 20 years at the start of the study. Hierarchical Linear Modeling was used to fit individual linear growth curves to the measures of syntax comprehension (TACL-R) and mean length of spontaneous utterances obtained in 12-min narrative tasks (MLU-S), yielding two parameters for each participant's comprehension and production: performance at study start and growth trajectory. Predictor variables were obtained by fitting linear growth curves to each individual's concurrent measures of nonverbal visual cognition (Pattern Analysis subtest of the Stanford-Binet), visual short-term memory (Bead Memory subtest), and auditory short-term memory (digit span), yielding two individual predictor parameters for each measure: performance at study start and growth trajectory. Chronological age at study start (grand-mean centered), sex, and hearing status were also taken as predictors. The best-fitting HLM model of the comprehension parameters uses age at study start, visual short-term memory, and auditory short-term memory as predictors of initial status and age at study start as a predictor of growth trajectory. The model accounted for 90% of the variance in intercept parameters, 79% of the variance in slope parameters, and 24% of the variance at level 1. The some predictors were significant predictors of initial status in the best model for production, with no measures predicting slope. The model accounted for 81% of the intercept variance and 43% of the level 1 variance. When comprehension parameters are added to the predictor set, the best model, accounting for 94% of the intercept and 22% of the slope variance, uses only comprehension at study start as a predictor of initial status and comprehension slope as a predictor of production slope. These results reflect the fact that expressive

  5. Hierarchical Linear Modeling for Analysis of Ecological Momentary Assessment Data in Physical Medicine and Rehabilitation Research.

    Science.gov (United States)

    Terhorst, Lauren; Beck, Kelly Battle; McKeon, Ashlee B; Graham, Kristin M; Ye, Feifei; Shiffman, Saul

    2017-08-01

    Ecological momentary assessment (EMA) methods collect real-time data in real-world environments, which allow physical medicine and rehabilitation researchers to examine objective outcome data and reduces bias from retrospective recall. The statistical analysis of EMA data is directly related to the research question and the temporal design of the study. Hierarchical linear modeling, which accounts for multiple observations from the same participant, is a particularly useful approach to analyzing EMA data. The objective of this paper was to introduce the process of conducting hierarchical linear modeling analyses with EMA data. This is accomplished using exemplars from recent physical medicine and rehabilitation literature.

  6. Linear growth in asthmatic children

    Directory of Open Access Journals (Sweden)

    Maria Ângela Reis de Góes Monteiro Antonio

    2003-01-01

    Full Text Available Asthma is the most frequent chronic inflammatory disease in childhood, and its prevalence has increased remarkably over the last decades. Therefore, the scientific community became interested in studying the growth of the affected children. The relationship between asthma and growth suffers the influence of the clinical picture, of therapeutics, but the different study methods make it difficult to distinguish the factors responsible for the growth retardation detected by some authors. This review has the purpose of providing an overall outlook on this matter.

  7. Meta-Analysis in Higher Education: An Illustrative Example Using Hierarchical Linear Modeling

    Science.gov (United States)

    Denson, Nida; Seltzer, Michael H.

    2011-01-01

    The purpose of this article is to provide higher education researchers with an illustrative example of meta-analysis utilizing hierarchical linear modeling (HLM). This article demonstrates the step-by-step process of meta-analysis using a recently-published study examining the effects of curricular and co-curricular diversity activities on racial…

  8. A Hierarchical Linear Model with Factor Analysis Structure at Level 2

    Science.gov (United States)

    Miyazaki, Yasuo; Frank, Kenneth A.

    2006-01-01

    In this article the authors develop a model that employs a factor analysis structure at Level 2 of a two-level hierarchical linear model (HLM). The model (HLM2F) imposes a structure on a deficient rank Level 2 covariance matrix [tau], and facilitates estimation of a relatively large [tau] matrix. Maximum likelihood estimators are derived via the…

  9. Examining Factors Affecting Science Achievement of Hong Kong in PISA 2006 Using Hierarchical Linear Modeling

    Science.gov (United States)

    Lam, Terence Yuk Ping; Lau, Kwok Chi

    2014-01-01

    This study uses hierarchical linear modeling to examine the influence of a range of factors on the science performances of Hong Kong students in PISA 2006. Hong Kong has been consistently ranked highly in international science assessments, such as Programme for International Student Assessment and Trends in International Mathematics and Science…

  10. Meta-Analysis in Higher Education: An Illustrative Example Using Hierarchical Linear Modeling

    Science.gov (United States)

    Denson, Nida; Seltzer, Michael H.

    2011-01-01

    The purpose of this article is to provide higher education researchers with an illustrative example of meta-analysis utilizing hierarchical linear modeling (HLM). This article demonstrates the step-by-step process of meta-analysis using a recently-published study examining the effects of curricular and co-curricular diversity activities on racial…

  11. Analyzing Multilevel Data: Comparing Findings from Hierarchical Linear Modeling and Ordinary Least Squares Regression

    Science.gov (United States)

    Rocconi, Louis M.

    2013-01-01

    This study examined the differing conclusions one may come to depending upon the type of analysis chosen, hierarchical linear modeling or ordinary least squares (OLS) regression. To illustrate this point, this study examined the influences of seniors' self-reported critical thinking abilities three ways: (1) an OLS regression with the student…

  12. Hierarchical Linear Modeling with Maximum Likelihood, Restricted Maximum Likelihood, and Fully Bayesian Estimation

    Science.gov (United States)

    Boedeker, Peter

    2017-01-01

    Hierarchical linear modeling (HLM) is a useful tool when analyzing data collected from groups. There are many decisions to be made when constructing and estimating a model in HLM including which estimation technique to use. Three of the estimation techniques available when analyzing data with HLM are maximum likelihood, restricted maximum…

  13. Missing Data Treatments at the Second Level of Hierarchical Linear Models

    Science.gov (United States)

    St. Clair, Suzanne W.

    2011-01-01

    The current study evaluated the performance of traditional versus modern MDTs in the estimation of fixed-effects and variance components for data missing at the second level of an hierarchical linear model (HLM) model across 24 different study conditions. Variables manipulated in the analysis included, (a) number of Level-2 variables with missing…

  14. Hierarchical linear modeling of longitudinal pedigree data for genetic association analysis

    DEFF Research Database (Denmark)

    Tan, Qihua; B Hjelmborg, Jacob V; Thomassen, Mads;

    2014-01-01

    on the mean level of a phenotype, they are not sufficiently straightforward to handle the kinship correlation on the time-dependent trajectories of a phenotype. We introduce a 2-level hierarchical linear model to separately assess the genetic associations with the mean level and the rate of change...

  15. Optimizing linear growth measurement in children.

    Science.gov (United States)

    Foote, Jan M

    2014-01-01

    A child's pattern of linear growth is one of the most sensitive indicators of health and well-being. However, many health care personnel use casual techniques and faulty instruments to measure children's growth and keep imprecise growth charts, making interpretation of growth patterns problematic. This situation can delay diagnosis and treatment of children with growth disorders and other conditions that affect growth. It can also lead to undue anxiety and unnecessary evaluation of children who are actually growing well. A clinical practice guideline was developed to optimize the accuracy and reliability of linear growth measurement. This article presents strategies to implement the guideline and thereby increase awareness of the importance of standardized growth measurement techniques and instruments, facilitate staff training and competency, and encourage standardized record keeping. These strategies will give providers more confidence in their interpretation of children's growth patterns and allow them to recognize potential problems, possibly before other symptoms appear.

  16. Hierarchical Shrinkage Priors and Model Fitting for High-dimensional Generalized Linear Models

    Science.gov (United States)

    Yi, Nengjun; Ma, Shuangge

    2013-01-01

    Genetic and other scientific studies routinely generate very many predictor variables, which can be naturally grouped, with predictors in the same groups being highly correlated. It is desirable to incorporate the hierarchical structure of the predictor variables into generalized linear models for simultaneous variable selection and coefficient estimation. We propose two prior distributions: hierarchical Cauchy and double-exponential distributions, on coefficients in generalized linear models. The hierarchical priors include both variable-specific and group-specific tuning parameters, thereby not only adopting different shrinkage for different coefficients and different groups but also providing a way to pool the information within groups. We fit generalized linear models with the proposed hierarchical priors by incorporating flexible expectation-maximization (EM) algorithms into the standard iteratively weighted least squares as implemented in the general statistical package R. The methods are illustrated with data from an experiment to identify genetic polymorphisms for survival of mice following infection with Listeria monocytogenes. The performance of the proposed procedures is further assessed via simulation studies. The methods are implemented in a freely available R package BhGLM (http://www.ssg.uab.edu/bhglm/). PMID:23192052

  17. Hierarchical Helical Order in the Twisted Growth of Plant Organs

    Science.gov (United States)

    Wada, Hirofumi

    2012-09-01

    The molecular and cellular basis of left-right asymmetry in plant morphogenesis is a fundamental issue in biology. A rapidly elongating root or hypocotyl of twisting mutants of Arabidopsis thaliana exhibits a helical growth with a handedness opposite to that of the underlying cortical microtubule arrays in epidermal cells. However, how such a hierarchical helical order emerges is currently unknown. We propose a model for investigating macroscopic chiral asymmetry in Arabidopsis mutants. Our elastic model suggests that the helical pattern observed is a direct consequence of the simultaneous presence of anisotropic growth and tilting of cortical microtubule arrays. We predict that the root helical pitch angle is a function of the microtubule helical angle and elastic moduli of the tissues. The proposed model is versatile and is potentially important for other biological systems ranging from protein fibrous structures to tree trunks.

  18. Correction: β-Sialon nanowires, nanobelts and hierarchical nanostructures: morphology control, growth mechanism and cathodoluminescence properties

    Science.gov (United States)

    Huang, Juntong; Huang, Zhaohui; Liu, Yangai; Fang, Minghao; Chen, Kai; Huang, Yaoting; Huang, Saifang; Ji, Haipeng; Yang, Jingzhou; Wu, Xiaowen; Zhang, Shaowei

    2016-07-01

    Correction for `β-Sialon nanowires, nanobelts and hierarchical nanostructures: morphology control, growth mechanism and cathodoluminescence properties' by Juntong Huang, et al., Nanoscale, 2014, 6, 424-432.

  19. Hospital- and patient-related characteristics determining maternity length of stay: a hierarchical linear model approach.

    Science.gov (United States)

    Leung, K M; Elashoff, R M; Rees, K S; Hasan, M M; Legorreta, A P

    1998-03-01

    The purpose of this study was to identify factors related to pregnancy and childbirth that might be predictive of a patient's length of stay after delivery and to model variations in length of stay. California hospital discharge data on maternity patients (n = 499,912) were analyzed. Hierarchical linear modeling was used to adjust for patient case mix and hospital characteristics and to account for the dependence of outcome variables within hospitals. Substantial variation in length of stay among patients was observed. The variation was mainly attributed to delivery type (vaginal or cesarean section), the patient's clinical risk factors, and severity of complications (if any). Furthermore, hospitals differed significantly in maternity lengths of stay even after adjustment for patient case mix. Developing risk-adjusted models for length of stay is a complex process but is essential for understanding variation. The hierarchical linear model approach described here represents a more efficient and appropriate way of studying interhospital variations than the traditional regression approach.

  20. The Impact of Neighborhood Characteristics on Housing Prices-An Application of Hierarchical Linear Modeling

    OpenAIRE

    Lee Chun Chang; Hui-Yu Lin

    2012-01-01

    Housing data are of a nested nature as houses are nested in a village, a town, or a county. This study thus applies HLM (hierarchical linear modelling) in an empirical study by adding neighborhood characteristic variables into the model for consideration. Using the housing data of 31 neighborhoods in the Taipei area as analysis samples and three HLM sub-models, this study discusses the impact of neighborhood characteristics on house prices. The empirical results indicate that the impact of va...

  1. Hierarchical Linear Modeling to Explore the Influence of Satisfaction with Public Facilities on Housing Prices

    OpenAIRE

    Chung-Chang Lee

    2009-01-01

    This paper uses hierarchical linear modeling (HLM) to explore the influence of satisfaction with public facilities on both individual residential and overall (or regional) levels on housing prices. The empirical results indicate that the average housing prices between local cities and counties exhibit significant variance. At the macro level, the explanatory power of the variable ¡§convenience of life¡¨ on the average housing prices of all counties and cities reaches the 5% significance level...

  2. To Aggregate or Not and Potentially Better Questions for Clustered Data: The Need for Hierarchical Linear Modeling in CTE Research

    Science.gov (United States)

    Nimon, Kim

    2012-01-01

    Using state achievement data that are openly accessible, this paper demonstrates the application of hierarchical linear modeling within the context of career technical education research. Three prominent approaches to analyzing clustered data (i.e., modeling aggregated data, modeling disaggregated data, modeling hierarchical data) are discussed…

  3. Study of the relationship between organizational culture and organizational outcomes using hierarchical linear modeling methodology.

    Science.gov (United States)

    Platonova, Elena A; Hernandez, S Robert; Shewchuk, Richard M; Leddy, Kelly M

    2006-01-01

    This study examines how perceptions of organizational culture influence organizational outcomes, specially, individual employee job satisfaction. The study was conducted in the health care industry in the United States. It examined the data on employee perceptions of job attributes, organizational culture, and job satisfaction, collected by Press Ganey Associates from 88 hospitals across the country in 2002-2003. Hierarchical linear modeling was used to test how organizational culture affects individual employee job satisfaction. Results indicated that some dimensions of organizational culture, specifically, job security and performance recognition, play a role in improving employee job satisfaction.

  4. Neighborhood Predictors of Intimate Partner Violence: A Theory-Informed Analysis Using Hierarchical Linear Modeling.

    Science.gov (United States)

    Voith, Laura A; Brondino, Michael J

    2017-09-01

    Due to high prevalence rates and deleterious effects on individuals, families, and communities, intimate partner violence (IPV) is a significant public health problem. Because IPV occurs in the context of communities and neighborhoods, research must examine the broader environment in addition to individual-level factors to successfully facilitate behavior change. Drawing from the Social Determinants of Health framework and Social Disorganization Theory, neighborhood predictors of IPV were tested using hierarchical linear modeling. Results indicated that concentrated disadvantage and female-to-male partner violence were robust predictors of women's IPV victimization. Implications for theory, practice, and policy, and future research are discussed. © Society for Community Research and Action 2017.

  5. Growth Mechanism of a Unique Hierarchical Vaterite Structure

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2013-03-01

    Calcium carbonate is one of the most significant minerals in nature as well as in biogenic sources. Calcium carbonate occurs naturally in three crystalline polymorphs, i.e., calcite, aragonite, and vaterite. Although it has been attracted much research attention to understanding of the formation mechanisms of the material, the properties of the vaterite polymorph is not well known. Here we report synthesis and formation mechanism of a unique hierarchical structure of vaterite. The material is grown by a controlled diffusion method. The structure possesses a core and an outer part. The core is convex lens-like and is formed by vaterite nanocrystals that have small misorientations. The outer part is separated into six garlic clove-like segments. Each segment possesses piles of plate-like vaterite crystals, and the orientations of the plates continuously change from pile to pile. Based on real-time experimental results and the structural analysis, a growth mechanism is presented. Work supported by NSFC (Grant No. 51172104) and MOST of China (Grant No. 2101CB630705)

  6. Emittance Growth in Linear Induction Accelerators

    OpenAIRE

    Ekdahl, Carl

    2017-01-01

    The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. Some of the possible causes for the emittance growth in the DARHT LIA have been investigated using particle-in-ce...

  7. Controlled Growth of a Hierarchical Nickel Carbide "Dandelion" Nanostructure.

    Science.gov (United States)

    Qiao, Liang; Zhao, Wenxia; Qin, Yueling; Swihart, Mark T

    2016-07-01

    We present a new type of highly hierarchical but nonporous nanostructure with a unique "dandelion" morphology. Based on the time evolution of these Ni3 C nanostructures, we suggest a mechanism for their formation. This type of hierarchical nanocrystal, with high accessible specific surface area in a relatively large (ca. 750 nm overall diameter) stable structure, can be valuable in catalysis and related applications.

  8. The impact of hierarchical memory systems on linear algebra algorithm design

    Energy Technology Data Exchange (ETDEWEB)

    Gallivan, K.; Jalby, W.; Meier, U.; Sameh, A.

    1987-09-14

    Performing an extremely detailed performance optimization analysis is counterproductive when the concern is performance behavior on a class of architecture, since general trends are obscured by the overwhelming number of machine-specific considerations required. Instead, in this paper, a methodology is used which identifies the effects of a hierarchical memory system on the performance of linear algebra algorithms on multivector processors; provides a means of producing a set of algorithm parameters, i.e., blocksizes, as functions of system parameters which yield near-optimal performance; and provides guidelines for algorithm designers which reduce the influence of the hierarchical memory system on algorithm performance to negligible levels and thereby allow them to concentrate on machine-specific optimizations. The remainder of this paper comprises five major discussions. First, the methodology and the attendant architectural model are discussed. Next, an analysis of the basic BLAS3 matrix-matrix primitive is presented. This is followed by a discussion of three block algorithms: a block LU decomposition, a block LDL/sup T/ decomposition and a block Gram-Schmidt algorithm. 22 refs., 9 figs.

  9. Hierarchical linear modeling (HLM) of longitudinal brain structural and cognitive changes in alcohol-dependent individuals during sobriety

    DEFF Research Database (Denmark)

    Yeh, P.H.; Gazdzinski, S.; Durazzo, T.C.;

    2007-01-01

    and unique hierarchical linear models allow assessments of the complex relationships among outcome measures of longitudinal data sets. These HLM applications suggest that chronic cigarette smoking modulates the temporal dynamics of brain structural and cognitive changes in alcoholics during prolonged......Background: Hierarchical linear modeling (HLM) can reveal complex relationships between longitudinal outcome measures and their covariates under proper consideration of potentially unequal error variances. We demonstrate the application of FILM to the study of magnetic resonance imaging (MRI...... time points. Using HLM, we modeled volumetric and cognitive outcome measures as a function of cigarette and alcohol use variables. Results: Different hierarchical linear models with unique model structures are presented and discussed. The results show that smaller brain volumes at baseline predict...

  10. Evidence for a non-universal Kennicutt-Schmidt relationship using hierarchical Bayesian linear regression

    CERN Document Server

    Shetty, Rahul; Bigiel, Frank

    2012-01-01

    We develop a Bayesian linear regression method which rigorously treats measurement uncertainties, and accounts for hierarchical data structure for investigating the relationship between the star formation rate and gas surface density. The method simultaneously estimates the intercept, slope, and scatter about the regression line of each individual subject (e.g. a galaxy) and the population (e.g. an ensemble of galaxies). Using synthetic datasets, we demonstrate that the Bayesian method accurately recovers the parameters of both the individuals and the population, especially when compared to commonly employed least squares methods, such as the bisector. We apply the Bayesian method to estimate the Kennicutt-Schmidt (KS) parameters of a sample of spiral galaxies compiled by Bigiel et al. (2008). We find significant variation in the KS parameters, indicating that no single KS relationship holds for all galaxies. This suggests that the relationship between molecular gas and star formation differs between galaxies...

  11. LIMO EEG: A Toolbox for Hierarchical LInear MOdeling of ElectroEncephaloGraphic Data

    Directory of Open Access Journals (Sweden)

    Cyril R. Pernet

    2011-01-01

    Full Text Available Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip. LIMO EEG is a Matlab toolbox (EEGLAB compatible to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses.

  12. Associations among attachment, sexuality, and marital satisfaction in adult Chilean couples: a linear hierarchical models analysis.

    Science.gov (United States)

    Heresi Milad, Eliana; Rivera Ottenberger, Diana; Huepe Artigas, David

    2014-01-01

    This study aimed to explore the associations among attachment system type, sexual satisfaction, and marital satisfaction in adult couples in stable relationships. Participants were 294 couples between the ages of 20 and 70 years who answered self-administered questionnaires. Hierarchical linear modeling revealed that the anxiety and avoidance, sexual satisfaction, and marital satisfaction dimensions were closely related. Specifically, the avoidance dimension, but not the anxiety dimension, corresponded to lower levels of sexual and marital satisfaction. Moreover, for the sexual satisfaction variable, an interaction effect was observed between the gender of the actor and avoidance of the partner, which was observed only in men. In the marital satisfaction dimension, effects were apparent only at the individual level; a positive relation was found between the number of years spent living together and greater contentment with the relationship. These results confirm the hypothetical association between attachment and sexual and marital satisfaction and demonstrate the relevance of methodologies when the unit of analysis is the couple.

  13. Meta-analysis methods for synthesizing treatment effects in multisite studies: hierarchical linear modeling (HLM perspective

    Directory of Open Access Journals (Sweden)

    Sema A. Kalaian

    2003-06-01

    Full Text Available The objectives of the present mixed-effects meta-analytic application are to provide practical guidelines to: (a Calculate..treatment effect sizes from multiple sites; (b Calculate the overall mean of the site effect sizes and their variances; (c..Model the heterogeneity in these site treatment effects as a function of site and program characteristics plus..unexplained random error using Hierarchical Linear Modeling (HLM; (d Improve the ability of multisite evaluators..and policy makers to reach sound conclusions about the effectiveness of educational and social interventions based on..multisite evaluations; and (e Illustrate the proposed methodology by applying these methods to real multi-site research..data.

  14. An exploratory analysis of treatment completion and client and organizational factors using hierarchical linear modeling.

    Science.gov (United States)

    Woodward, Albert; Das, Abhik; Raskin, Ira E; Morgan-Lopez, Antonio A

    2006-11-01

    Data from the Alcohol and Drug Services Study (ADSS) are used to analyze the structure and operation of the substance abuse treatment industry in the United States. Published literature contains little systematic empirical analysis of the interaction between organizational characteristics and treatment outcomes. This paper addresses that deficit. It develops and tests a hierarchical linear model (HLM) to address questions about the empirical relationship between treatment inputs (industry costs, types and use of counseling and medical personnel, diagnosis mix, patient demographics, and the nature and level of services used in substance abuse treatment), and patient outcomes (retention and treatment completion rates). The paper adds to the literature by demonstrating a direct and statistically significant link between treatment completion and the organizational and staffing structure of the treatment setting. Related reimbursement issues, questions for future analysis, and limitations of the ADSS for this analysis are discussed.

  15. Personality change over 40 years of adulthood: hierarchical linear modeling analyses of two longitudinal samples.

    Science.gov (United States)

    Helson, Ravenna; Jones, Constance; Kwan, Virginia S Y

    2002-09-01

    Normative personality change over 40 years was shown in 2 longitudinal cohorts with hierarchical linear modeling of California Psychological Inventory data obtained at multiple times between ages 21-75. Although themes of change and the paucity of differences attributable to gender and cohort largely supported findings of multiethnic cross-sectional samples, the authors also found much quadratic change and much individual variability. The form of quadratic change supported predictions about the influence of period of life and social climate as factors in change over the adult years: Scores on Dominance and Independence peaked in the middle age of both cohorts, and scores on Responsibility were lowest during peak years of the culture of individualism. The idea that personality change is most pronounced before age 30 and then reaches a plateau received no support.

  16. LIMO EEG: a toolbox for hierarchical LInear MOdeling of ElectroEncephaloGraphic data.

    Science.gov (United States)

    Pernet, Cyril R; Chauveau, Nicolas; Gaspar, Carl; Rousselet, Guillaume A

    2011-01-01

    Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB) and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses.

  17. The Asian clam Corbicula fluminea as a biomonitor of trace element contamination: accounting for different sources of variation using an hierarchical linear model.

    Science.gov (United States)

    Shoults-Wilson, W Aaron; Peterson, James T; Unrine, Jason M; Rickard, James; Black, Marsha C

    2009-10-01

    In the present study, specimens of the invasive clam, Corbicula fluminea, were collected above and below possible sources of potentially toxic trace elements (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the Altamaha River system (Georgia, U.S.A.). Bioaccumulation of these elements was quantified, along with environmental (water and sediment) concentrations. Hierarchical linear models were used to account for variability in tissue concentrations related to environmental (site water chemistry and sediment characteristics) and individual (growth metrics) variables while identifying the strongest relations between these variables and trace element accumulation. The present study found significantly elevated concentrations of Cd, Cu, and Hg downstream of the outfall of kaolin-processing facilities, Zn downstream of a tire cording facility, and Cr downstream of both a nuclear power plant and a paper pulp mill. Models of the present study indicated that variation in trace element accumulation was linked to distance upstream from the estuary, dissolved oxygen, percentage of silt and clay in the sediment, elemental concentrations in sediment, shell length, and bivalve condition index. By explicitly modeling environmental variability, the Hierarchical linear modeling procedure allowed the identification of sites showing increased accumulation of trace elements that may have been caused by human activity. Hierarchical linear modeling is a useful tool for accounting for environmental and individual sources of variation in bioaccumulation studies.

  18. Longitudinal hierarchical linear modeling analyses of California Psychological Inventory data from age 33 to 75: an examination of stability and change in adult personality.

    Science.gov (United States)

    Jones, Constance J; Livson, Norman; Peskin, Harvey

    2003-06-01

    Twenty aspects of personality assessed via the California Psychological Inventory (CPI; Gough & Bradley, 1996) from age 33 to 75 were examined in a sample of 279 individuals. Oakland Growth Study and Berkeley Guidance Study members completed the CPI a maximum of 4 times. We used longitudinal hierarchical linear modeling (HLM) to ask the following: Which personality characteristics change and which do not? Five CPI scales showed uniform lack of change, 2 showed heterogeneous change giving an averaged lack of change, 4 showed linear increases with age, 2 showed linear decreases with age, 4 showed gender or sample differences in linear change, 1 showed a quadratic peak, and 2 showed a quadratic nadir. The utility of HLM becomes apparent in portraying the complexity of personality change and stability.

  19. Emittance growth in linear induction accelerators

    CERN Document Server

    Ekdahl, C A; Schulze, M E; Carlson, C A; Frayer, D K; Mostrum, C; Thoma, C H

    2014-01-01

    The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.

  20. A Hierarchical Bayesian Setting for an Inverse Problem in Linear Parabolic PDEs with Noisy Boundary Conditions

    KAUST Repository

    Ruggeri, Fabrizio

    2016-05-12

    In this work we develop a Bayesian setting to infer unknown parameters in initial-boundary value problems related to linear parabolic partial differential equations. We realistically assume that the boundary data are noisy, for a given prescribed initial condition. We show how to derive the joint likelihood function for the forward problem, given some measurements of the solution field subject to Gaussian noise. Given Gaussian priors for the time-dependent Dirichlet boundary values, we analytically marginalize the joint likelihood using the linearity of the equation. Our hierarchical Bayesian approach is fully implemented in an example that involves the heat equation. In this example, the thermal diffusivity is the unknown parameter. We assume that the thermal diffusivity parameter can be modeled a priori through a lognormal random variable or by means of a space-dependent stationary lognormal random field. Synthetic data are used to test the inference. We exploit the behavior of the non-normalized log posterior distribution of the thermal diffusivity. Then, we use the Laplace method to obtain an approximated Gaussian posterior and therefore avoid costly Markov Chain Monte Carlo computations. Expected information gains and predictive posterior densities for observable quantities are numerically estimated using Laplace approximation for different experimental setups.

  1. Exploring the Effects of Congruence and Holland's Personality Codes on Job Satisfaction: An Application of Hierarchical Linear Modeling Techniques

    Science.gov (United States)

    Ishitani, Terry T.

    2010-01-01

    This study applied hierarchical linear modeling to investigate the effect of congruence on intrinsic and extrinsic aspects of job satisfaction. Particular focus was given to differences in job satisfaction by gender and by Holland's first-letter codes. The study sample included nationally represented 1462 female and 1280 male college graduates who…

  2. Exploring the Effects of Congruence and Holland's Personality Codes on Job Satisfaction: An Application of Hierarchical Linear Modeling Techniques

    Science.gov (United States)

    Ishitani, Terry T.

    2010-01-01

    This study applied hierarchical linear modeling to investigate the effect of congruence on intrinsic and extrinsic aspects of job satisfaction. Particular focus was given to differences in job satisfaction by gender and by Holland's first-letter codes. The study sample included nationally represented 1462 female and 1280 male college graduates who…

  3. Motivation, Classroom Environment, and Learning in Introductory Geology: A Hierarchical Linear Model

    Science.gov (United States)

    Gilbert, L. A.; Hilpert, J. C.; Van Der Hoeven Kraft, K.; Budd, D.; Jones, M. H.; Matheney, R.; Mcconnell, D. A.; Perkins, D.; Stempien, J. A.; Wirth, K. R.

    2013-12-01

    Prior research has indicated that highly motivated students perform better and that learning increases in innovative, reformed classrooms, but untangling the student effects from the instructor effects is essential to understanding how to best support student learning. Using a hierarchical linear model, we examine these effects separately and jointly. We use data from nearly 2,000 undergraduate students surveyed by the NSF-funded GARNET (Geoscience Affective Research NETwork) project in 65 different introductory geology classes at research universities, public masters-granting universities, liberal arts colleges and community colleges across the US. Student level effects were measured as increases in expectancy and self-regulation using the Motivated Strategies for Learning Questionnaire (MSLQ; Pintrich et al., 1991). Instructor level effects were measured using the Reformed Teaching Observation Protocol, (RTOP; Sawada et al., 2000), with higher RTOP scores indicating a more reformed, student-centered classroom environment. Learning was measured by learning gains on a Geology Concept Inventory (GCI; Libarkin and Anderson, 2005) and normalized final course grade. The hierarchical linear model yielded significant results at several levels. At the student level, increases in expectancy and self-regulation are significantly and positively related to higher grades regardless of instructor; the higher the increase, the higher the grade. At the instructor level, RTOP scores are positively related to normalized average GCI learning gains. The higher the RTOP score, the higher the average class GCI learning gains. Across both levels, average class GCI learning gains are significantly and positively related to student grades; the higher the GCI learning gain, the higher the grade. Further, the RTOP scores are significantly and negatively related to the relationship between expectancy and course grade. The lower the RTOP score, the higher the correlation between change in

  4. Examining Factors Affecting Science Achievement of Hong Kong in PISA 2006 Using Hierarchical Linear Modeling

    Science.gov (United States)

    Lam, Terence Yuk Ping; Lau, Kwok Chi

    2014-10-01

    This study uses hierarchical linear modeling to examine the influence of a range of factors on the science performances of Hong Kong students in PISA 2006. Hong Kong has been consistently ranked highly in international science assessments, such as Programme for International Student Assessment and Trends in International Mathematics and Science Study; therefore, an exploration of the factors that affect science performances of Hong Kong students can give a lens to examine how science education can be improved in Hong Kong and other countries. The analyses reveal that student backgrounds as male, at higher grade levels, and born in mainland (when in the same grade) are associated with better science performance. Among the attitudinal factors, enjoyment of science and self-efficacy in science play important roles in scientific achievements. Most of the parental factors, on the other hand, are not having significant impacts on achievement after student attitudes are taken into account, with only parents' value of science having a small effect. School student intake is found to be a strong predictor of school average achievement, as well as a major mediator of the effects of school enrollment size and school socio-economic status. The findings differ from recently reported results, which suggested that school enrollment size was associated with achievement. This study also points out the problems of the use of science instruction time as a school-level variable to explain science achievement in Hong Kong.

  5. Hierarchical linear modeling of longitudinal pedigree data for genetic association analysis.

    Science.gov (United States)

    Tan, Qihua; B Hjelmborg, Jacob V; Thomassen, Mads; Jensen, Andreas Kryger; Christiansen, Lene; Christensen, Kaare; Zhao, Jing Hua; Kruse, Torben A

    2014-01-01

    Genetic association analysis on complex phenotypes under a longitudinal design involving pedigrees encounters the problem of correlation within pedigrees, which could affect statistical assessment of the genetic effects. Approaches have been proposed to integrate kinship correlation into the mixed-effect models to explicitly model the genetic relationship. These have proved to be an efficient way of dealing with sample clustering in pedigree data. Although current algorithms implemented in popular statistical packages are useful for adjusting relatedness in the mixed modeling of genetic effects on the mean level of a phenotype, they are not sufficiently straightforward to handle the kinship correlation on the time-dependent trajectories of a phenotype. We introduce a 2-level hierarchical linear model to separately assess the genetic associations with the mean level and the rate of change of a phenotype, integrating kinship correlation in the analysis. We apply our method to the Genetic Analysis Workshop 18 genome-wide association studies data on chromosome 3 to estimate the genetic effects on systolic blood pressure measured over time in large pedigrees. Our method identifies genetic variants associated with blood pressure with estimated inflation factors of 0.99, suggesting that our modeling of random effects efficiently handles the genetic relatedness in pedigrees. Application to simulated data captures important variants specified in the simulation. Our results show that the method is useful for genetic association studies in related samples using longitudinal design.

  6. Establishing Causality Using Longitudinal Hierarchical Linear Modeling: An Illustration Predicting Achievement From Self-Control.

    Science.gov (United States)

    Duckworth, Angela Lee; Tsukayama, Eli; May, Henry

    2010-10-01

    The predictive validity of personality for important life outcomes is well established, but conventional longitudinal analyses cannot rule out the possibility that unmeasured third-variable confounds fully account for the observed relationships. Longitudinal hierarchical linear models (HLM) with time-varying covariates allow each subject to serve as his or her own control, thus eliminating between-individual confounds. HLM also allows the directionality of the causal relationship to be tested by reversing time-lagged predictor and outcome variables. We illustrate these techniques through a series of models that demonstrate that within-individual changes in self-control over time predict subsequent changes in GPA but not vice-versa. The evidence supporting a causal role for self-control was not moderated by IQ, gender, ethnicity, or income. Further analyses rule out one time-varying confound: self-esteem. The analytic approach taken in this study provides the strongest evidence to date for the causal role of self-control in determining achievement.

  7. Working memory contributions to relative clause attachment processing: a hierarchical linear modeling analysis.

    Science.gov (United States)

    Traxler, Matthew J

    2007-07-01

    An eye-movement-monitoring experiment tested readers' responses to sentences containing relative clauses that could be attached to one or both of two preceding nouns. Previous experiments with such sentences have indicated that globally ambiguous relative clauses are processed more quickly than are determinately attached relative clauses. Central to the present research, a recent study (Swets, Desmet, Hambrick, & Ferreira, 2007) showed that offline preferences for such sentences differ as a function of working memory capacity. Specifically, both English and Dutch participants' preference for the second of two nouns as the host for the relative clause increased as their working memory capacity increased. In the present study, readers' working memory capacity was measured, and eye movements were monitored. Hierarchical linear modeling was used to determine whether working memory capacity moderated readers' online processing performance. The modeling indicated that determinately attached sentences were harder to process than globally ambiguous sentences, that working memory did not affect processing of the relative clause itself, but that working memory did moderate how easy it was to integrate the relative clause with the preceding sentence context. Specifically, in contrast with the offline results from Swets and colleagues' study, readers with higher working memory capacity were more likely to prefer the first noun over the second noun as the host for the relative clause.

  8. Analysis of HIV medication adherence in relation to person and treatment characteristics using hierarchical linear modeling.

    Science.gov (United States)

    Halkitis, Perry; Palamar, Joseph; Mukherjee, Preetika

    2008-04-01

    The purpose of this investigation was to consider person characteristics, treatment level variables, and illicit drug use to help explain the HIV antiviral adherence patterns of a community-based, non-drug-treatment-seeking sample of men who have sex with men (MSM). Adherence data were gathered for 300 MSM eight times over the course of 1 year using electronic monitoring. Treatment and person level characteristics were assessed at baseline assessment using computer-administered surveys, and drug usage was established via a diagnostic inventory. These longitudinal data were analyzed via Hierarchical Linear Modeling. The sample was diverse in terms of age and race/ethnicity. Across the span of the year in which the participants were assessed, adherence rates were relatively stable and high (means: 82% to 90%) at each time point and remained relatively stable across the yearlong investigation. Lower adherence rates were evident among those who were drug users, black identified (in terms of race), older, and by pill burden. Individuals on HIV antiretroviral therapy demonstrated consistent although not optimal adherence rates when assessed during the course of a year. The significance of numerous person level factors such as age, race, and drug use suggest that adherence to treatment may in part be impacted by the circumstances that the individual brings to the treatment behavior, and suggests interventions that delve beyond the behavioral to consider and address life social and intrapersonal circumstances that may interfere with adherence behaviors.

  9. Determination of a Differential Item Functioning Procedure Using the Hierarchical Generalized Linear Model

    Directory of Open Access Journals (Sweden)

    Tülin Acar

    2012-01-01

    Full Text Available The aim of this research is to compare the result of the differential item functioning (DIF determining with hierarchical generalized linear model (HGLM technique and the results of the DIF determining with logistic regression (LR and item response theory–likelihood ratio (IRT-LR techniques on the test items. For this reason, first in this research, it is determined whether the students encounter DIF with HGLM, LR, and IRT-LR techniques according to socioeconomic status (SES, in the Turkish, Social Sciences, and Science subtest items of the Secondary School Institutions Examination. When inspecting the correlations among the techniques in terms of determining the items having DIF, it was discovered that there was significant correlation between the results of IRT-LR and LR techniques in all subtests; merely in Science subtest, the results of the correlation between HGLM and IRT-LR techniques were found significant. DIF applications can be made on test items with other DIF analysis techniques that were not taken to the scope of this research. The analysis results, which were determined by using the DIF techniques in different sample sizes, can be compared.

  10. Using hierarchical linear modeling to explore predictors of pain after total hip and knee arthroplasty as a consequence of osteoarthritis.

    Science.gov (United States)

    Halket, Ashley; Stratford, Paul W; Kennedy, Deborah M; Woodhouse, Linda J

    2010-02-01

    Hierarchical linear modeling was used to establish differences in, and the average pattern of, recovery of the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and 2 composite performance-specific measures of pain as well as to determine if significant individual variations exist in the growth curves for each measure. Predictors of postoperative pain were also of interest. One hundred forty-seven patients undergoing unilateral primary hip or knee arthroplasty completed 4 performance measures-self-paced 40-m walk, timed up and go, stair test, and 6-minute walk-and the WOMAC prearthroplasty and at multiple points in time between 2 and 27 weeks postarthroplasty. Although patients reported different levels of postoperative pain initially, similar recovery patterns were noted. Predictive variables were found to be site of joint arthroplasty and WOMAC prearthroplasty pain scores for the WOMAC pain subscale, the site of joint arthroplasty and sex for the first composite pain score, and sex for the second composite. 2010 Elsevier Inc. All rights reserved.

  11. Hierarchical generalized linear models for multiple groups of rare and common variants: jointly estimating group and individual-variant effects.

    Directory of Open Access Journals (Sweden)

    Nengjun Yi

    2011-12-01

    Full Text Available Complex diseases and traits are likely influenced by many common and rare genetic variants and environmental factors. Detecting disease susceptibility variants is a challenging task, especially when their frequencies are low and/or their effects are small or moderate. We propose here a comprehensive hierarchical generalized linear model framework for simultaneously analyzing multiple groups of rare and common variants and relevant covariates. The proposed hierarchical generalized linear models introduce a group effect and a genetic score (i.e., a linear combination of main-effect predictors for genetic variants for each group of variants, and jointly they estimate the group effects and the weights of the genetic scores. This framework includes various previous methods as special cases, and it can effectively deal with both risk and protective variants in a group and can simultaneously estimate the cumulative contribution of multiple variants and their relative importance. Our computational strategy is based on extending the standard procedure for fitting generalized linear models in the statistical software R to the proposed hierarchical models, leading to the development of stable and flexible tools. The methods are illustrated with sequence data in gene ANGPTL4 from the Dallas Heart Study. The performance of the proposed procedures is further assessed via simulation studies. The methods are implemented in a freely available R package BhGLM (http://www.ssg.uab.edu/bhglm/.

  12. Hierarchical Generalized Linear Models for Multiple Groups of Rare and Common Variants: Jointly Estimating Group and Individual-Variant Effects

    Science.gov (United States)

    Yi, Nengjun; Liu, Nianjun; Zhi, Degui; Li, Jun

    2011-01-01

    Complex diseases and traits are likely influenced by many common and rare genetic variants and environmental factors. Detecting disease susceptibility variants is a challenging task, especially when their frequencies are low and/or their effects are small or moderate. We propose here a comprehensive hierarchical generalized linear model framework for simultaneously analyzing multiple groups of rare and common variants and relevant covariates. The proposed hierarchical generalized linear models introduce a group effect and a genetic score (i.e., a linear combination of main-effect predictors for genetic variants) for each group of variants, and jointly they estimate the group effects and the weights of the genetic scores. This framework includes various previous methods as special cases, and it can effectively deal with both risk and protective variants in a group and can simultaneously estimate the cumulative contribution of multiple variants and their relative importance. Our computational strategy is based on extending the standard procedure for fitting generalized linear models in the statistical software R to the proposed hierarchical models, leading to the development of stable and flexible tools. The methods are illustrated with sequence data in gene ANGPTL4 from the Dallas Heart Study. The performance of the proposed procedures is further assessed via simulation studies. The methods are implemented in a freely available R package BhGLM (http://www.ssg.uab.edu/bhglm/). PMID:22144906

  13. Stability of fMRI striatal response to alcohol cues: a hierarchical linear modeling approach.

    Science.gov (United States)

    Schacht, Joseph P; Anton, Raymond F; Randall, Patrick K; Li, Xingbao; Henderson, Scott; Myrick, Hugh

    2011-05-01

    In functional magnetic resonance imaging (fMRI) studies of alcohol-dependent individuals, alcohol cues elicit activation of the ventral and dorsal aspects of the striatum (VS and DS), which are believed to underlie aspects of reward learning critical to the initiation and maintenance of alcohol dependence. Cue-elicited striatal activation may represent a biological substrate through which treatment efficacy may be measured. However, to be useful for this purpose, VS or DS activation must first demonstrate stability across time. Using hierarchical linear modeling (HLM), this study tested the stability of cue-elicited activation in anatomically and functionally defined regions of interest in bilateral VS and DS. Nine non-treatment-seeking alcohol-dependent participants twice completed an alcohol cue reactivity task during two fMRI scans separated by 14 days. HLM analyses demonstrated that, across all participants, alcohol cues elicited significant activation in each of the regions of interest. At the group level, these activations attenuated slightly between scans, but session-wise differences were not significant. Within-participants stability was best in the anatomically defined right VS and DS and in a functionally defined region that encompassed right caudate and putamen (intraclass correlation coefficients of .75, .81, and .76, respectively). Thus, within this small sample, alcohol cue-elicited fMRI activation had good reliability in the right striatum, though a larger sample is necessary to ensure generalizability and further evaluate stability. This study also demonstrates the utility of HLM analytic techniques for serial fMRI studies, in which separating within-participants variance (individual changes in activation) from between-participants factors (time or treatment) is critical. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. The effects of oestrogens on linear bone growth

    DEFF Research Database (Denmark)

    Juul, A

    2001-01-01

    Regulation of linear bone growth in children and adolescents comprises a complex interaction of hormones and growth factors. Growth hormone (GH) is considered to be the key hormone regulator of linear growth in childhood. The pubertal increase in growth velocity associated with GH has traditionally...... female growth spurt despite lack of androgen action. Oestrogens may also influence linear bone growth indirectly via modulation of the GH-insulin-like growth factor-I (IGF-I) axis. Thus, ER blockade diminishes endogenous GH secretion, androgen receptor (AR) blockade increases GH secretion in peripubertal...... boys, and non-aromatizable androgens [oxandrolone or dihydrotestosterone (DHT)] have no effect on GH secretion. Treatment with aromatase inhibitors reduces circulating IGF-I concentrations in healthy males, and reduces growth in boys with testotoxicosis. Taken together, these findings suggest...

  15. A hierarchical linear modeling assessment of dual-addiction status and change in sexual compulsivity over time.

    Science.gov (United States)

    Wright, Paul J

    2010-08-01

    This study examined the association between dual-addiction status and sexual compulsivity over time in a sample of self-identified sexually compulsive males. Hierarchical linear modeling was utilized to address the study's research questions. Dually addicted sexually compulsive males exhibited lower rates of sexual compulsivity than their singularly addicted counterparts initially but displayed less precipitous declines in sexual compulsiveness over time. Implications for treatment providers are discussed.

  16. Piecewise Linear-Linear Latent Growth Mixture Models with Unknown Knots

    Science.gov (United States)

    Kohli, Nidhi; Harring, Jeffrey R.; Hancock, Gregory R.

    2013-01-01

    Latent growth curve models with piecewise functions are flexible and useful analytic models for investigating individual behaviors that exhibit distinct phases of development in observed variables. As an extension of this framework, this study considers a piecewise linear-linear latent growth mixture model (LGMM) for describing segmented change of…

  17. Hierarchical structure of the countries based on electricity consumption and economic growth

    Science.gov (United States)

    Kantar, Ersin; Aslan, Alper; Deviren, Bayram; Keskin, Mustafa

    2016-07-01

    We investigate the hierarchical structures of countries based on electricity consumption and economic growth by using the real amounts of their consumption over a certain time period. We use electricity consumption data to detect the topological properties of 64 countries from 1971 to 2008. These countries are divided into three clusters: low income group, middle income group and high income group countries. Firstly, a relationship between electricity consumption and economic growth is investigated by using the concept of hierarchical structure methods (minimal spanning tree (MST) and hierarchical tree (HT)). Secondly, we perform bootstrap techniques to investigate a value of the statistical reliability to the links of the MST. Finally, we use a clustering linkage procedure in order to observe the cluster structure more clearly. The results of the structural topologies of these trees are as follows: (i) we identified different clusters of countries according to their geographical location and economic growth, (ii) we found a strong relation between energy consumption and economic growth for all the income groups considered in this study and (iii) the results are in good agreement with the causal relationship between electricity consumption and economic growth.

  18. Evaluating the Impacts of ICT Use: A Multi-Level Analysis with Hierarchical Linear Modeling

    Science.gov (United States)

    Song, Hae-Deok; Kang, Taehoon

    2012-01-01

    The purpose of this study is to evaluate the impacts of ICT use on achievements by considering not only ICT use, but also the process and background variables that influence ICT use at both the student- and school-level. This study was conducted using data from the 2010 Survey of Seoul Education Longitudinal Research. A Hierarchical Linear…

  19. Hierarchical Linear Models for Energy Prediction using Inertial Sensors: A Comparative Study for Treadmill Walking.

    Science.gov (United States)

    Vathsangam, Harshvardhan; Emken, B Adar; Schroeder, E Todd; Spruijt-Metz, Donna; Sukhatme, Gaurav S

    2013-12-01

    Walking is a commonly available activity to maintain a healthy lifestyle. Accurately tracking and measuring calories expended during walking can improve user feedback and intervention measures. Inertial sensors are a promising measurement tool to achieve this purpose. An important aspect in mapping inertial sensor data to energy expenditure is the question of normalizing across physiological parameters. Common approaches such as weight scaling require validation for each new population. An alternative is to use a hierarchical approach to model subject-specific parameters at one level and cross-subject parameters connected by physiological variables at a higher level. In this paper, we evaluate an inertial sensor-based hierarchical model to measure energy expenditure across a target population. We first determine the optimal movement and physiological features set to represent data. Periodicity based features are more accurate (phierarchical model with a subject-specific regression model and weight exponent scaled models. Subject-specific models perform significantly better (pmodels at all exponent scales whereas the hierarchical model performed worse than both. However, using an informed prior from the hierarchical model produces similar errors to using a subject-specific model with large amounts of training data (phierarchical modeling is a promising technique for generalized prediction energy expenditure prediction across a target population in a clinical setting.

  20. booc.io: An Education System with Hierarchical Concept Maps and Dynamic Non-linear Learning Plans.

    Science.gov (United States)

    Schwab, Michail; Strobelt, Hendrik; Tompkin, James; Fredericks, Colin; Huff, Connor; Higgins, Dana; Strezhnev, Anton; Komisarchik, Mayya; King, Gary; Pfister, Hanspeter

    2017-01-01

    Information hierarchies are difficult to express when real-world space or time constraints force traversing the hierarchy in linear presentations, such as in educational books and classroom courses. We present booc.io, which allows linear and non-linear presentation and navigation of educational concepts and material. To support a breadth of material for each concept, booc.io is Web based, which allows adding material such as lecture slides, book chapters, videos, and LTIs. A visual interface assists the creation of the needed hierarchical structures. The goals of our system were formed in expert interviews, and we explain how our design meets these goals. We adapt a real-world course into booc.io, and perform introductory qualitative evaluation with students.

  1. Hierarchical linear modeling (HLM) of longitudinal brain structural and cognitive changes in alcohol-dependent individuals during sobriety.

    Science.gov (United States)

    Yeh, Ping-Hong; Gazdzinski, Stefan; Durazzo, Timothy C; Sjöstrand, Karl; Meyerhoff, Dieter J

    2007-12-01

    Hierarchical linear modeling (HLM) can reveal complex relationships between longitudinal outcome measures and their covariates under proper consideration of potentially unequal error variances. We demonstrate the application of HLM to the study of magnetic resonance imaging (MRI)-derived brain volume changes and cognitive changes in abstinent alcohol-dependent individuals as a function of smoking status, smoking severity, and drinking quantities. Twenty non-smoking recovering alcoholics (nsALC) and 30 age-matched smoking recovering alcoholics (sALC) underwent quantitative MRI and cognitive assessments at 1 week, 1 month, and 7 months of sobriety. Eight non-smoking light drinking controls were studied at baseline and 7 months later. Brain and ventricle volumes at each time point were quantified using MRI masks, while the boundary shift integral method measured volume changes between time points. Using HLM, we modeled volumetric and cognitive outcome measures as a function of cigarette and alcohol use variables. Different hierarchical linear models with unique model structures are presented and discussed. The results show that smaller brain volumes at baseline predict faster brain volume gains, which were also related to greater smoking and drinking severities. Over 7 months of abstinence from alcohol, sALC compared to nsALC showed less improvements in visuospatial learning and memory despite larger brain volume gains and ventricular shrinkage. Different and unique hierarchical linear models allow assessments of the complex relationships among outcome measures of longitudinal data sets. These HLM applications suggest that chronic cigarette smoking modulates the temporal dynamics of brain structural and cognitive changes in alcoholics during prolonged sobriety.

  2. Linear growth of structure in massive bigravity

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, Adam R. [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Rd., Cambridge CB3 0WA (United Kingdom); Akrami, Yashar [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway); Koivisto, Tomi S., E-mail: a.r.solomon@damtp.cam.ac.uk, E-mail: yashar.akrami@astro.uio.no, E-mail: tomi.koivisto@nordita.org [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)

    2014-10-01

    The ghost-free theory of massive gravity with two dynamical metrics has been shown to produce viable cosmological expansion, where the late-time acceleration of the Universe is due to the finite range of the gravitational interaction rather than a nonzero cosmological constant. Here the cosmological perturbations are studied in this theory. The full perturbation equations are presented in a general gauge and analyzed, focusing on subhorizon scales in the quasistatic limit during the matter-dominated era. An evolution equation for the matter inhomogeneities and the parameters quantifying the deviations from general relativistic structure formation are expressed in terms of five functions whose forms are determined directly by the coupling parameters in the theory. The evolution equation has a similar structure to Horndeski-type scalar-tensor theories, exhibiting a modified growth rate and scale-dependence at intermediate wavenumbers. Predictions of the theory are confronted with observational data on both background expansion and large-scale structure, although care must be taken to ensure a model is stable. It is found that while the stable models fit the data well, they feature deviations from the standard cosmology that could be detected or ruled out by near-future experiments.

  3. Greater expectations: using hierarchical linear modeling to examine expectancy for treatment outcome as a predictor of treatment response.

    Science.gov (United States)

    Price, Matthew; Anderson, Page; Henrich, Christopher C; Rothbaum, Barbara Olasov

    2008-12-01

    A client's expectation that therapy will be beneficial has long been considered an important factor contributing to therapeutic outcomes, but recent empirical work examining this hypothesis has primarily yielded null findings. The present study examined the contribution of expectancies for treatment outcome to actual treatment outcome from the start of therapy through 12-month follow-up in a clinical sample of individuals (n=72) treated for fear of flying with either in vivo exposure or virtual reality exposure therapy. Using a piecewise hierarchical linear model, outcome expectancy predicted treatment gains made during therapy but not during follow-up. Compared to lower levels, higher expectations for treatment outcome yielded stronger rates of symptom reduction from the beginning to the end of treatment on 2 standardized self-report questionnaires on fear of flying. The analytic approach of the current study is one potential reason that findings contrast with prior literature. The advantages of using hierarchical linear modeling to assess interindividual differences in longitudinal data are discussed.

  4. Pedagogical Representations to Teach Linear Relations in Chinese and U.S. Classrooms: Parallel or Hierarchical?

    Science.gov (United States)

    Huang, Rongjin; Cai, Jinfa

    2011-01-01

    This study investigates Chinese and U.S. teachers' construction and use of pedagogical representations surrounding implementation of mathematical tasks. It does this by analyzing video-taped lessons from the Learner's Perspective Study, involving 15 Chinese and 10 U.S. consecutive lessons on the topic of linear equations/linear relations. We…

  5. Non-linear Growth Models in Mplus and SAS.

    Science.gov (United States)

    Grimm, Kevin J; Ram, Nilam

    2009-10-01

    Non-linear growth curves or growth curves that follow a specified non-linear function in time enable researchers to model complex developmental patterns with parameters that are easily interpretable. In this paper we describe how a variety of sigmoid curves can be fit using the Mplus structural modeling program and the non-linear mixed-effects modeling procedure NLMIXED in SAS. Using longitudinal achievement data collected as part of a study examining the effects of preschool instruction on academic gain we illustrate the procedures for fitting growth models of logistic, Gompertz, and Richards functions. Brief notes regarding the practical benefits, limitations, and choices faced in the fitting and estimation of such models are included.

  6. Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function.

    Science.gov (United States)

    Vuori, Kaarina; Strandén, Ismo; Sevón-Aimonen, Marja-Liisa; Mäntysaari, Esa A

    2006-01-01

    A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.

  7. Linear grain growth kinetics and rotation in nanocrystalline Ni

    OpenAIRE

    Farkas, Diana; Mohanty, S.; Monk, J.

    2007-01-01

    We report three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Ni. The results show the grain size increasing linearly with time, contrary to the square root of the time kinetics observed in coarse-grained structures. The average grain boundary energy per unit area decreases simultaneously with the decrease in total grain boundary area associated with grain growth. The average mobility of the boundaries increases as the grain size increases. The r...

  8. Remarks on Hierarchic Control for a Linearized Micropolar Fluids System in Moving Domains

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Isaías Pereira de, E-mail: isaias@ufpi.edu.br [Universidade Federal do Piauí, Dpto. Matemática (Brazil)

    2015-12-15

    We study a Stackelberg strategy subject to the evolutionary linearized micropolar fluids equations in domains with moving boundaries, considering a Nash multi-objective equilibrium (non necessarily cooperative) for the “follower players” (as is called in the economy field) and an optimal problem for the leader player with approximate controllability objective. We will obtain the following main results: the existence and uniqueness of Nash equilibrium and its characterization, the approximate controllability of the linearized micropolar system with respect to the leader control and the existence and uniqueness of the Stackelberg–Nash problem, where the optimality system for the leader is given.

  9. Hierarchical linear modeling analyses of the NEO-PI-R scales in the Baltimore Longitudinal Study of Aging.

    Science.gov (United States)

    Terracciano, Antonio; McCrae, Robert R; Brant, Larry J; Costa, Paul T

    2005-09-01

    The authors examined age trends in the 5 factors and 30 facets assessed by the Revised NEO Personality Inventory in Baltimore Longitudinal Study of Aging data (N=1,944; 5,027 assessments) collected between 1989 and 2004. Consistent with cross-sectional results, hierarchical linear modeling analyses showed gradual personality changes in adulthood: a decline in Neuroticism up to age 80, stability and then decline in Extraversion, decline in Openness, increase in Agreeableness, and increase in Conscientiousness up to age 70. Some facets showed different curves from the factor they define. Birth cohort effects were modest, and there were no consistent Gender x Age interactions. Significant nonnormative changes were found for all 5 factors; they were not explained by attrition but might be due to genetic factors, disease, or life experience. Copyright (c) 2005 APA, all rights reserved.

  10. Hierarchical Linear Modeling Analyses of NEO-PI-R Scales In the Baltimore Longitudinal Study of Aging

    Science.gov (United States)

    Terracciano, Antonio; McCrae, Robert R.; Brant, Larry J.; Costa, Paul T.

    2009-01-01

    We examined age trends in the five factors and 30 facets assessed by the Revised NEO Personality Inventory in Baltimore Longitudinal Study of Aging data (N = 1,944; 5,027 assessments) collected between 1989 and 2004. Consistent with cross-sectional results, Hierarchical Linear Modeling analyses showed gradual personality changes in adulthood: a decline up to age 80 in Neuroticism, stability and then decline in Extraversion, decline in Openness, increase in Agreeableness, and increase up to age 70 in Conscientiousness. Some facets showed different curves from the factor they define. Birth cohort effects were modest, and there were no consistent Gender × Age interactions. Significant non-normative changes were found for all five factors; they were not explained by attrition but might be due to genetic factors, disease, or life experience. PMID:16248708

  11. A Hierarchical Generalized Linear Model in Combination with Dispersion Modeling to Improve Sib-Pair Linkage Analysis.

    Science.gov (United States)

    Lee, Woojoo; Kim, Jeonghwan; Lee, Youngjo; Park, Taesung; Suh, Young Ju

    2015-01-01

    We explored a hierarchical generalized linear model (HGLM) in combination with dispersion modeling to improve the sib-pair linkage analysis based on the revised Haseman-Elston regression model for a quantitative trait. A dispersion modeling technique was investigated for sib-pair linkage analysis using simulation studies and real data applications. We considered 4 heterogeneous dispersion settings according to a signal-to-noise ratio (SNR) in the various statistical models based on the Haseman-Elston regression model. Our numerical studies demonstrated that susceptibility loci could be detected well by modeling the dispersion parameter appropriately. In particular, the HGLM had better performance than the linear regression model and the ordinary linear mixed model when the SNR is low, i.e., when substantial noise was present in the data. The study shows that the HGLM in combination with dispersion modeling can be utilized to identify multiple markers showing linkage to familial complex traits accurately. Appropriate dispersion modeling might be more powerful to identify markers closest to the major genes which determine a quantitative trait. © 2015 S. Karger AG, Basel.

  12. The linear growth of structure in the Rh = ct universe

    Science.gov (United States)

    Melia, Fulvio

    2017-01-01

    We use recently published redshift space distortion measurements of the cosmological growth rate, fσ8(z), to examine whether the linear evolution of perturbations in the Rh = ct cosmology is consistent with the observed development of large-scale structure. We find that these observations favour Rh = ct over the version of Λ cold dark matter (ΛCDM) optimized with the joint analysis of Planck and linear growth rate data, particularly in the redshift range 0 data. When ΛCDM is optimized using solely the growth rate measurements; however, the two models fit the observations equally well though, in this case, the low-redshift measurements find a lower value for the fluctuation amplitude than is expected in Planck ΛCDM. Our results strongly affirm the need for more precise measurements of fσ8(z) at all redshifts, but especially at z < 1.

  13. Application of a Hierarchical Linear Model to the Study of Adolescent Deviance in an Overlapping Cohort Design.

    Science.gov (United States)

    Raudenbush, Stephen W.; Chan, Wing-Shing

    1993-01-01

    Used data on attitudes toward deviance during adolescence to illustrate assessment of psychometric properties of instrument for studying change, compare adequacy of linear and curvilinear growth models, control for time invariant and time-varying covariates, and link overlapping data cohorts. Findings suggest that prodeviant attitudes increased…

  14. The relationship between carbon dioxide emission and economic growth: Hierarchical structure methods

    Science.gov (United States)

    Deviren, Seyma Akkaya; Deviren, Bayram

    2016-06-01

    Carbon dioxide (CO2) emission has an essential role in the current debate on sustainable development and environmental protection. CO2 emission is also directly linked with use of energy which plays a focal role both for production and consumption in the world economy. Therefore the relationship between the CO2 emission and economic growth has a significant implication for the environmental and economical policies. In this study, within the scope of sociophysics, the topology, taxonomy and relationships among the 33 countries, which have almost the high CO2 emission and economic growth values, are investigated by using the hierarchical structure methods, such as the minimal spanning tree (MST) and hierarchical tree (HT), over the period of 1970-2010. The average linkage cluster analysis (ALCA) is also used to examine the cluster structure more clearly in HTs. According to their proximity, economic ties and economic growth, different clusters of countries are identified from the structural topologies of these trees. We have found that the high income & OECD countries are closely connected to each other and are isolated from the upper middle and lower middle income countries from the MSTs, which are obtained both for the CO2 emission and economic growth. Moreover, the high income & OECD clusters are homogeneous with respect to the economic activities and economic ties of the countries. It is also mentioned that the Group of Seven (G7) countries (CAN, ENG, FRA, GER, ITA, JPN, USA) are connected to each other and these countries are located at the center of the MST for the results of CO2 emission. The same analysis may also successfully apply to the other environmental sources and different countries.

  15. Non-linear growth and condensation in multiplex networks

    CERN Document Server

    Nicosia, Vincenzo; Latora, Vito; Barthelemy, Marc

    2013-01-01

    Different types of interactions coexist and coevolve to shape the structure and function of a multiplex network. We propose here a general class of growth models in which the various layers of a multiplex network coevolve through a set of non-linear preferential attachment rules. We show, both numerically and analytically, that by tuning the level of non-linearity these models allow to reproduce either homogeneous or heterogeneous degree distributions, together with positive or negative degree correlations across layers. In particular, we derive the condition for the appearance of a condensed state in which a single node connects to nearly all other nodes of a layer.

  16. Hierarchical linear modeling of visual acuity change over time: rate of functional recovery after macular hole surgery.

    Science.gov (United States)

    Wittich, Walter; Overbury, Olga; Kapusta, Michael A; Watanabe, Donald H

    2007-09-01

    To examine acuity recovery rate after Macular Hole (MH) surgery, using Hierarchical Linear Modeling (HLM) with linear and curvilinear regression analysis. Preoperative MH diameter (OCT) and acuity (ETDRS) were recorded in 20 eyes. Acuities were tested during follow-up (6 to 23 months), with three to eight measurements per eye. The resulting 95 acuities were analyzed using HLM. Variability at the level of the person was explained by change over time, using a natural logarithm conversion. Across patients, MH diameter was used to predict slopes and intercepts at the level of the individual. MH diameter was able to account for significant amounts of variability in preoperative acuity (intercept) and significantly influenced rate of functional recovery (slope). A nonlinear approach to the data accounted for the largest amount of variance. Participants with larger MHs recovered relatively more acuity sooner while eyes with smaller MHs had better absolute acuity outcome. HLM provides important insight into the recovery process after MH surgery and is more flexible with follow-up data. In the context of MH treatment, most recuperation occurred during the initial 6 months.

  17. Factors Associated With Rehabilitation Outcomes After Traumatic Brain Injury: Comparing Functional Outcomes Between TBIMS Centers Using Hierarchical Linear Modeling.

    Science.gov (United States)

    Dahdah, Marie N; Hofmann, Melissa; Pretz, Christopher; An, Viktoriya; Barnes, Sunni A; Bennett, Monica; Dreer, Laura E; Bergquist, Thomas; Shafi, Shahid

    To examine differences in patient outcomes across Traumatic Brain Injury Model Systems (TBIMS) rehabilitation centers and factors that influence these differences using hierarchical linear modeling (HLM). Sixteen TBIMS centers. A total of 2056 individuals 16 years or older with moderate to severe traumatic brain injury (TBI) who received inpatient rehabilitation. Multicenter observational cohort study using HLM to analyze prospectively collected data. Functional Independence Measure and Disability Rating Scale total scores at discharge and 1 year post-TBI. Duration of posttraumatic amnesia (PTA) demonstrated a significant inverse relationship with functional outcomes. However, the magnitude of this relationship (change in functional status for each additional day in PTA) varied among centers. Functional status at discharge from rehabilitation and at 1 year post-TBI could be predicted using the slope and intercept of each TBIMS center for the duration of PTA, by comparing it against the average slope and intercept. HLM demonstrated center effect due to variability in the relationship between PTA and functional outcomes of patients. This variability is not accounted for in traditional linear regression modeling. Future studies examining variations in patient outcomes between centers should utilize HLM to measure the impact of additional factors that influence patient rehabilitation functional outcomes.

  18. Contributions of Individual Differences and Contextual Variables to Reading Achievement of English Language Learners: An Empirical Investigation Using Hierarchical Linear Modeling

    Science.gov (United States)

    Ardasheva, Yuliya; Tretter, Thomas R.

    2013-01-01

    This nonexperimental study explored the relationships among individual differences, contextual variables, and reading achievement of English language learners (ELLs) in one large urban school district in the United States. The sample comprised 840 students in Grades 3-8 and 10 nested within 37 schools. Hierarchical linear modeling results indicate…

  19. Reconstruction of late Holocene climate based on tree growth and mechanistic hierarchical models

    Science.gov (United States)

    Tipton, John; Hooten, Mevin B.; Pederson, Neil; Tingley, Martin; Bishop, Daniel

    2016-01-01

    Reconstruction of pre-instrumental, late Holocene climate is important for understanding how climate has changed in the past and how climate might change in the future. Statistical prediction of paleoclimate from tree ring widths is challenging because tree ring widths are a one-dimensional summary of annual growth that represents a multi-dimensional set of climatic and biotic influences. We develop a Bayesian hierarchical framework using a nonlinear, biologically motivated tree ring growth model to jointly reconstruct temperature and precipitation in the Hudson Valley, New York. Using a common growth function to describe the response of a tree to climate, we allow for species-specific parameterizations of the growth response. To enable predictive backcasts, we model the climate variables with a vector autoregressive process on an annual timescale coupled with a multivariate conditional autoregressive process that accounts for temporal correlation and cross-correlation between temperature and precipitation on a monthly scale. Our multi-scale temporal model allows for flexibility in the climate response through time at different temporal scales and predicts reasonable climate scenarios given tree ring width data.

  20. Non-linear plasma wake growth of electron holes

    Science.gov (United States)

    Hutchinson, I. H.; Haakonsen, C. B.; Zhou, C.

    2015-03-01

    An object's wake in a plasma with small Debye length that drifts across the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable size, beyond which their uncontrolled growth disrupts the ions. The hole growth calculations provide a quantitative prediction of hole profile and size evolution. Hole growth appears to explain the observations of recent particle-in-cell simulations.

  1. Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function

    Directory of Open Access Journals (Sweden)

    Mäntysaari Esa A

    2006-06-01

    Full Text Available Abstract A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.

  2. Non-Linear Behaviour Of Gelatin Networks Reveals A Hierarchical Structure

    KAUST Repository

    Yang, Zhi

    2015-12-14

    We investigate the strain hardening behaviour of various gelatin networks - namely physically-crosslinked gelatin gel, chemically-crosslinked gelatin gels, and a hybrid gels made of a combination of the former two - under large shear deformations using the pre-stress, strain ramp, and large amplitude oscillation shear protocols. Further, the internal structures of physically-crosslinked gelatin gel and chemically-crosslinked gelatin gels were characterized by small angle neutron scattering (SANS) to enable their internal structures to be correlated with their nonlinear rheology. The Kratky plots of SANS data demonstrate the presence of small cross-linked aggregates within the chemically-crosslinked network, whereas in the physically-crosslinked gels a relatively homogeneous structure is observed. Through model fitting to the scattering data, we were able to obtain structural parameters, such as correlation length (ξ), cross-sectional polymer chain radius (Rc), and the fractal dimension (df) of the gel networks. The fractal dimension df obtained from the SANS data of the physically-crosslinked and chemically crosslinked gels is 1.31 and 1.53, respectively. These values are in excellent agreement with the ones obtained from a generalized non-linear elastic theory we used to fit our stress-strain curves. The chemical crosslinking that generates coils and aggregates hinders the free stretching of the triple helices bundles in the physically-crosslinked gels.

  3. Evolution of platinum hierarchical microstructure amine - Assisted growth via solvothermal method

    Science.gov (United States)

    Ooi, Mahayatun Dayana Johan; Aziz, Azlan Abdul

    2015-04-01

    Here we studied the formation of Platinum hierarchical microstructure by varying the synthesis time using amine assisted growth via solvothermal method. A small cluster of particles was produced at a shorter synthesis time (5h) while fully grown flower-like microstructure were formed at 9h of reaction. The synthesized Pt particles exhibit high absorption peak at 230 nm corresponding to Pt absorption peak. The catalytic property of the synthesized Pt is greatly influenced by its geometrical shape. The fully grown flower-like particles exhibit large electrochemical surface area (4.88 cm-2 g-1) and catalytic stability at a longer period, which can serve as a potential catalyst for electro-oxidation of formic acid.

  4. Stepwise Splitting Growth and Pseudocapacitive Properties of Hierarchical Three-Dimensional Co3O4 Nanobooks

    Directory of Open Access Journals (Sweden)

    Huilong Chen

    2017-04-01

    Full Text Available Three-dimensional hierarchical Co3O4 nanobooks have been synthesized successfully on a large scale by calcining orthorhombic Co(CO30.5(OH·0.11H2O precursors with identical morphologies. Based on the influence of reaction time and urea concentration on the nanostructures of the precursors, a stepwise splitting growth mechanism can be proposed to understand the formation of the 3D nanobooks. The 3D Co3O4 nanobooks exhibit excellent pseudocapacitive performances with specific capacitances of 590, 539, 476, 453, and 421 F/g at current densities of 0.5, 1, 2, 4, and 8 A/g, respectively. The devices can retain ca. 97.4% of the original specific capacitances after undergoing charge–discharge cycle tests 1000 times continuously at 4 A/g.

  5. The effect of maternal psychopathology on parent-child agreement of child anxiety symptoms: A hierarchical linear modeling approach.

    Science.gov (United States)

    Affrunti, Nicholas W; Woodruff-Borden, Janet

    2015-05-01

    The current study examined the effects of maternal anxiety, worry, depression, child age and gender on mother and child reports of child anxiety using hierarchical linear modeling. Participants were 73 mother-child dyads with children between the ages of 7 and 10 years. Reports of child anxiety symptoms, including symptoms of specific disorders (e.g., social phobia) were obtained using concordant versions of the Screen for Anxiety and Related Emotional Disorders (SCARED). Children reported significantly higher levels of anxiety symptoms relative to their mothers. Maternal worry and depression predicted for significantly lower levels of maternal-reported child anxiety and increasing discrepant reports. Maternal anxiety predicted for higher levels of maternal-reported child anxiety and decreasing discrepant reports. Maternal depression was associated with increased child-reported child anxiety symptoms. No significant effect of child age or gender was observed. Findings may inform inconsistencies in previous studies on reporter discrepancies. Implications and future directions are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Using Hierarchical Linear Modeling to Examine How Individual SLPs Differentially Contribute to Children's Language and Literacy Gains in Public Schools.

    Science.gov (United States)

    Farquharson, Kelly; Tambyraja, Sherine R; Logan, Jessica; Justice, Laura M; Schmitt, Mary Beth

    2015-08-01

    The purpose of this study was twofold: (a) to determine the unique contributions in children's language and literacy gains, over 1 academic year, that are attributable to the individual speech-language pathologist (SLP) and (b) to explore possible child- and SLP-level factors that may further explain SLPs' contributions to children's language and literacy gains. Participants were 288 kindergarten and 1st-grade children with language impairment who were currently receiving school-based language intervention from SLPs. Using hierarchical linear modeling, we partitioned the variance in children's gains in language (i.e., grammar, vocabulary) and literacy (i.e., word decoding) that could be attributed to their individual SLP. Results revealed a significant contribution of individual SLPs to children's gains in grammar, vocabulary, and word decoding. Children's fall language scores and grade were significant predictors of SLPs' contributions, although no SLP-level predictors were significant. The present study makes a first step toward incorporating implementation science and suggests that, for children receiving school-based language intervention, variance in child language and literacy gains in an academic year is at least partially attributable to SLPs. Continued work in this area should examine the possible SLP-level characteristics that may further explicate the relative contributions of SLPs.

  7. Hierarchical multivariate mixture generalized linear models for the analysis of spatial data: An application to disease mapping.

    Science.gov (United States)

    Torabi, Mahmoud

    2016-09-01

    Disease mapping of a single disease has been widely studied in the public health setup. Simultaneous modeling of related diseases can also be a valuable tool both from the epidemiological and from the statistical point of view. In particular, when we have several measurements recorded at each spatial location, we need to consider multivariate models in order to handle the dependence among the multivariate components as well as the spatial dependence between locations. It is then customary to use multivariate spatial models assuming the same distribution through the entire population density. However, in many circumstances, it is a very strong assumption to have the same distribution for all the areas of population density. To overcome this issue, we propose a hierarchical multivariate mixture generalized linear model to simultaneously analyze spatial Normal and non-Normal outcomes. As an application of our proposed approach, esophageal and lung cancer deaths in Minnesota are used to show the outperformance of assuming different distributions for different counties of Minnesota rather than assuming a single distribution for the population density. Performance of the proposed approach is also evaluated through a simulation study. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. A comprehensive meta-analysis of Triple P-Positive Parenting Program using hierarchical linear modeling: effectiveness and moderating variables.

    Science.gov (United States)

    Nowak, Christoph; Heinrichs, Nina

    2008-09-01

    A meta-analysis encompassing all studies evaluating the impact of the Triple P-Positive Parenting Program on parent and child outcome measures was conducted in an effort to identify variables that moderate the program's effectiveness. Hierarchical linear models (HLM) with three levels of data were employed to analyze effect sizes. The results (N=55 studies) indicate that Triple P causes positive changes in parenting skills, child problem behavior and parental well-being in the small to moderate range, varying as a function of the intensity of the intervention. The most salient findings of variables moderating the interventions' impact were larger effects found on parent report as compared to observational measures and more improvement associated with more intensive formats and initially more distressed families. Sample characteristics (e.g., child's age, being a boy) and methodological features (e.g., study quality) exhibited different degrees of predictive power. The analysis clearly identified several strengths of the Triple P system, most importantly its ability to effect meaningful improvement in parents and children. Some limitations pertain to the small evidence-base of certain formats of Triple P and the lack of follow-up data beyond 3 years after the intervention. Many of the present findings may be relevant to other evidence-based parenting programs.

  9. Ethnic differences in the effect of parenting on gang involvement and gang delinquency: a longitudinal, hierarchical linear modeling perspective.

    Science.gov (United States)

    Walker-Barnes, C J; Mason, C A

    2001-01-01

    This study examined the relative influence of peer and parenting behavior on changes in adolescent gang involvement and gang-related delinquency. An ethnically diverse sample of 300 ninth-grade students was recruited and assessed on eight occasions during the school year. Analyses were conducted using hierarchical linear modeling. Results indicated that, in general, adolescents decreased their level of gang involvement over the course of the school year, whereas the average level of gang delinquency remained constant over time. As predicted, adolescent gang involvement and gang-related delinquency were most strongly predicted by peer gang involvement and peer gang delinquency, respectively. Nevertheless, parenting behavior continued to significantly predict change in both gang involvement and gang delinquency, even after controlling for peer behavior. A significant interaction between parenting and ethnic and cultural heritage found the effect of parenting to be particularly salient for Black students, for whom higher levels of behavioral control and lower levels of lax parental control were related to better behavioral outcomes over time, whereas higher levels of psychological control predicted worse behavioral outcomes.

  10. Non-linear optical titanyl arsenates: Crystal growth and properties

    Science.gov (United States)

    Nordborg, Jenni Eva Louise

    Crystals are appreciated not only for their appearance, but also for their unique physical properties which are utilized by the photonic industry in appliances that we come across every day. An important part of enabling the technical use of optical devices is the manufacture of crystals. This dissertation deals with a specific group of materials called the potassium titanyl phosphate (KIP) family, known for their non-linear optical and ferroelectric properties. The isomorphs vary in their linear optical and dielectric properties, which can be tuned to optimize device performance by forming solid solutions of the different materials. Titanyl arsenates have a wide range of near-infrared transmission which makes them useful for tunable infrared lasers. The isomorphs examined in the present work were primarily RbTiOASO4 (RTA) and CsTiOAsO4 (CTA) together with the mixtures RbxCs 1-xTiOAsO4 (RCTA). Large-scale crystals were grown by top seeding solution growth utilizing a three-zone furnace with excellent temperature control. Sufficiently slow cooling and constant upward lifting produced crystals with large volumes useable for technical applications. Optical quality RTA crystals up to 10 x 12 x 20 mm were grown. The greater difficulty in obtaining good crystals of CTA led to the use of mixed RCTA materials. The mixing of rubidium and cesium in RCTA is more favorable to crystal growth than the single components in pure RTA and CTA. Mixed crystals are rubidium-enriched and contain only 20-30% of the cesium concentration in the flux. The cesium atoms show a preference for the larger cation site. The network structure is very little affected by the cation substitution; consequently, the non-linear optical properties of the Rb-rich isomorphic mixtures of RTA and CTA can be expected to remain intact. Crystallographic methods utilizing conventional X-ray tubes, synchrotron radiation and neutron diffraction have been employed to investigate the properties of the atomic

  11. Hierarchical polymeric scaffolds support the growth of MC3T3-E1 cells.

    Science.gov (United States)

    Akbarzadeh, Rosa; Minton, Joshua A; Janney, Cara S; Smith, Tyler A; James, Paul F; Yousefi, Azizeh-Mitra

    2015-02-01

    Tissue engineering makes use of the principles of biology and engineering to sustain 3D cell growth and promote tissue repair and/or regeneration. In this study, macro/microporous scaffold architectures have been developed using a hybrid solid freeform fabrication/thermally induced phase separation (TIPS) technique. Poly(lactic-co-glycolic acid) (PLGA) dissolved in 1,4-dioxane was used to generate a microporous matrix by the TIPS method. The 3D-bioplotting technique was used to fabricate 3D macroporous constructs made of polyethylene glycol (PEG). Embedding the PEG constructs inside the PLGA solution prior to the TIPS process and subsequent extraction of PEG following solvent removal (1,4-dioaxane) resulted in a macro/microporous structure. These hierarchical scaffolds with a bimodal pore size distribution (300 μm) contained orthogonally interconnected macro-channels generated by the extracted PEG. The diameter of the macro-channels was varied by tuning the dispensing parameters of the 3D bioplotter. The in vitro cell culture using murine MC3T3-E1 cell line for 21 days demonstrated that these scaffolds could provide a favorable environment to support cell adhesion and growth.

  12. [Determinants of weight and linear growth deficits in children under two years of age].

    Science.gov (United States)

    Oliveira, Valterlinda Alves de; Assis, Ana Marlúcia Oliveira; Pinheiro, Sandra Maria Conceição; Barreto, Mauricio Lima

    2006-10-01

    To identify determinants of protein-energy malnutrition resulting in weight and linear growth deficits in children. A cross-sectional study was carried out among 1,041 children (under two years of age) from 10 municipalities in Bahia, Northeastern Brazil, during 1999-2000. Both logistic regression and a hierarchical approach were used to identify factors associated with the anthropometric measures. The basic determinant found in the final model for linear growth retardation was having up to two household appliances (OR=2.9; 95% CI: 1.74-4.90); as an underlying determinant, not attending prenatal visits (OR=2.7; 95% CI: 1.47-4.97); and, among immediate determinants were low birth weight (OR=3.6; 95% CI: 1.72-7.70) and reported hospitalization within 12 months before the interview (OR=2.4; 95% CI: 1.42-4.10). Determinants of weight deficit at the basic, underlying and immediate levels were: per capita monthly income of less than one-fourth of the minimum wage (OR=3.4; 95% CI: 1.41-8.16), not attending prenatal visits (OR=2.1; 95% CI: 1.03-4.35) and low birth weight (OR=4.8; 95% CI: 2.00-11.48) respectively. Children's weight and linear deficits were accounted for the overlapping of poor material living conditions, limited access to health care and disease burden. Interventions aimed at improving living conditions and better access to health care programs are strategies towards equity in children's health and nutrition.

  13. New insights into the nature of cerebellar-dependent eyeblink conditioning deficits in schizophrenia: A hierarchical linear modeling approach

    Directory of Open Access Journals (Sweden)

    Amanda R Bolbecker

    2016-01-01

    Full Text Available Evidence of cerebellar dysfunction in schizophrenia has mounted over the past several decades, emerging from neuroimaging, neuropathological, and behavioral studies. Consistent with these findings, cerebellar-dependent delay eyeblink conditioning (dEBC deficits have been identified in schizophrenia. While repeated measures analysis of variance (ANOVA is traditionally used to analyze dEBC data, hierarchical linear modeling (HLM more reliably describes change over time by accounting for the dependence in repeated measures data. This analysis approach is well suited to dEBC data analysis because it has less restrictive assumptions and allows unequal variances. The current study examined dEBC measured with electromyography in a single-cue tone paradigm in an age-matched sample of schizophrenia participants and healthy controls (N=56 per group using HLM. Subjects participated in 90 trials (10 blocks of dEBC, during which a 400 ms tone co-terminated with a 50 ms air puff delivered to the left eye. Each block also contained 1 tone-alone trial. The resulting block averages of dEBC data were fitted to a 3-parameter logistic model in HLM, revealing significant differences between schizophrenia and control groups on asymptote and inflection point, but not slope. These findings suggest that while the learning rate is not significantly different compared to controls, associative learning begins to level off later and a lower ultimate level of associative learning is achieved in schizophrenia. Given the large sample size in the present study, HLM may provide a more nuanced and definitive analysis of differences between schizophrenia and controls on dEBC.

  14. How much do differences in medical schools influence student performance? A longitudinal study employing hierarchical linear modeling.

    Science.gov (United States)

    Hecker, Kent; Violato, Claudio

    2008-01-01

    Medical school curricula have undergone considerable change in the past half century. There is little evidence, however, for the impact of various curricula and educational policies on student learning once incoming performance and the nonrandom nature of students nested within schools has been accounted for. To investigate effects of school variables on United States Medical Licensing Examination (USMLE) Step 1-3 scores over an 11-year period (1994-2004). Using Association of American Medical Colleges and USMLE longitudinal data for 116 medical schools, hierarchical linear modeling was used to study the effects of school variables on Step 1-3. Mean unadjusted between school variance was 14.74%, 10.50%, and 11.25%, for USMLE Step 1-3. When student covariates were included, between-school variation was less than 5%. The variance accounted for in student performance by the student covariates ranged from 27.58% to 36.51% for Step 1,16.37% to 24.48% for Step 2 and 19.22% to 25.32% for Step 3.The proportion of the between-school variance that was accounted for by the student covariates ranged between 81.22% and 88.26% for Step 1, 48.44% and 79.77% for Step 2, and 68.41% and 80.78% for Step 3 [corrected]. School-level variables did not consistently predict for adjusted mean school Step performance. Individual student differences account for most of the variation in USMLE performance with small contributions from between-school variation and even smaller contribution from curriculum and educational policies.

  15. New Insights into the Nature of Cerebellar-Dependent Eyeblink Conditioning Deficits in Schizophrenia: A Hierarchical Linear Modeling Approach.

    Science.gov (United States)

    Bolbecker, Amanda R; Petersen, Isaac T; Kent, Jerillyn S; Howell, Josselyn M; O'Donnell, Brian F; Hetrick, William P

    2016-01-01

    Evidence of cerebellar dysfunction in schizophrenia has mounted over the past several decades, emerging from neuroimaging, neuropathological, and behavioral studies. Consistent with these findings, cerebellar-dependent delay eyeblink conditioning (dEBC) deficits have been identified in schizophrenia. While repeated-measures analysis of variance is traditionally used to analyze dEBC data, hierarchical linear modeling (HLM) more reliably describes change over time by accounting for the dependence in repeated-measures data. This analysis approach is well suited to dEBC data analysis because it has less restrictive assumptions and allows unequal variances. The current study examined dEBC measured with electromyography in a single-cue tone paradigm in an age-matched sample of schizophrenia participants and healthy controls (N = 56 per group) using HLM. Subjects participated in 90 trials (10 blocks) of dEBC, during which a 400 ms tone co-terminated with a 50 ms air puff delivered to the left eye. Each block also contained 1 tone-alone trial. The resulting block averages of dEBC data were fitted to a three-parameter logistic model in HLM, revealing significant differences between schizophrenia and control groups on asymptote and inflection point, but not slope. These findings suggest that while the learning rate is not significantly different compared to controls, associative learning begins to level off later and a lower ultimate level of associative learning is achieved in schizophrenia. Given the large sample size in the present study, HLM may provide a more nuanced and definitive analysis of differences between schizophrenia and controls on dEBC.

  16. Hierarchical Network Design

    DEFF Research Database (Denmark)

    Thomadsen, Tommy

    2005-01-01

    of different types of hierarchical networks. This is supplemented by a review of ring network design problems and a presentation of a model allowing for modeling most hierarchical networks. We use methods based on linear programming to design the hierarchical networks. Thus, a brief introduction to the various....... The thesis investigates models for hierarchical network design and methods used to design such networks. In addition, ring network design is considered, since ring networks commonly appear in the design of hierarchical networks. The thesis introduces hierarchical networks, including a classification scheme...... linear programming based methods is included. The thesis is thus suitable as a foundation for study of design of hierarchical networks. The major contribution of the thesis consists of seven papers which are included in the appendix. The papers address hierarchical network design and/or ring network...

  17. Hierarchical TiO2 nanospheres with dominant {001} facets: facile synthesis, growth mechanism, and photocatalytic activity.

    Science.gov (United States)

    Li, Hongmei; Zeng, Yangsu; Huang, Tongcheng; Piao, Lingyu; Yan, Zijie; Liu, Min

    2012-06-11

    Hierarchical TiO(2) nanospheres with controlled surface morphologies and dominant {001} facets were directly synthesized from Ti powder by a facile, one-pot, hydrothermal method. The obtained hierarchical TiO(2) nanospheres have a uniform size of 400-500 nm and remarkable 78 % fraction of {001} facets. The influence of the reaction temperature, amount of HF, and reaction time on the morphology and the exposed facets was systematically studied. A possible growth mechanism speculates that Ti powder first dissolves in HF solution, and then flowerlike TiO(2) nanostructures are formed by assembly of TiO(2) nanocrystals. Because of the high concentration of HF in the early stage, these TiO(2) nanostructures were etched, and hollow structures formed on the surface. After the F(-) ions were effectively absorbed on the crystal surfaces, {001} facets appear and grow steadily. At the same time, the {101} facets also grow and meet the {101} facets from adjacent truncated tetragonal pyramids, causing coalescence of these facets and formation of nanospheres with dominant {001} facets. With further extension of the reaction time, single-crystal {001} facets of hierarchical TiO(2) nanospheres are dissolved and TiO(2) nanospheres with dominant {101} facets are obtained. The photocatalytic activities of the hierarchical TiO(2) nanospheres were evaluated and found to be closely related to the exposed {001} facets. Owing to the special hierarchical architecture and high percentage of exposed {001} facets, the TiO(2) nanospheres exhibit much enhanced photocatalytic efficiency (almost fourfold) compared to P25 TiO(2) as a benchmark material. This study provides new insight into crystal-facet engineering of anatase TiO(2) nanostructures with high percentage of {001} facets as well as opportunities for controllable synthesis of 3D hierarchical nanostructures.

  18. Linear Growth of Structure in the Symmetron Model

    CERN Document Server

    Brax, Philippe; Davis, Anne-Christine; Li, Baojiu; Schmauch, Benoit; Shaw, Douglas J

    2011-01-01

    In the symmetron mechanism, the fifth force mediated by a coupled scalar field (the symmetron) is suppressed in high-density regions due to the restoration of symmetry in the symmetron potential. In this paper we study the background cosmology and large scale structure formation in the linear perturbation regime of the symmetron model. Analytic solutions to the symmetron in the cosmological background are found, which agree well with numerical results. We discuss the effect of the symmetron perturbation on the growth of matter perturbation, in particular the implications of the brief period of tachyonic instability caused by the negative mass squared of the symmetron during symmetry breaking. Our analysis and numerical results show that this instability has only very small effects on the growth of structures on sub-horizon scales, and even at horizon scales its influence is not as drastic as naively expected. The symmetron fifth force in the non-tachyonic regime does affect the formation of structure in a non...

  19. Hydrothermal Fabrication of WO3 Hierarchical Architectures: Structure, Growth and Response

    Directory of Open Access Journals (Sweden)

    Chuan-Sheng Wu

    2015-07-01

    Full Text Available Recently hierarchical architectures, consisting of two-dimensional (2D nanostructures, are of great interest for potential applications in energy and environmental. Here, novel rose-like WO3 hierarchical architectures were successfully synthesized via a facile hydrothermal method. The as-prepared WO3 hierarchical architectures were in fact assembled by numerous nanosheets with an average thickness of ~30 nm. We found that the oxalic acid played a significant role in governing morphologies of WO3 during hydrothermal process. Based on comparative studies, a possible formation mechanism was also proposed in detail. Furthermore, gas-sensing measurement showed that the well-defined 3D WO3 hierarchical architectures exhibited the excellent gas sensing properties towards CO.

  20. Hierarchical photocatalysts.

    Science.gov (United States)

    Li, Xin; Yu, Jiaguo; Jaroniec, Mietek

    2016-05-01

    As a green and sustainable technology, semiconductor-based heterogeneous photocatalysis has received much attention in the last few decades because it has potential to solve both energy and environmental problems. To achieve efficient photocatalysts, various hierarchical semiconductors have been designed and fabricated at the micro/nanometer scale in recent years. This review presents a critical appraisal of fabrication methods, growth mechanisms and applications of advanced hierarchical photocatalysts. Especially, the different synthesis strategies such as two-step templating, in situ template-sacrificial dissolution, self-templating method, in situ template-free assembly, chemically induced self-transformation and post-synthesis treatment are highlighted. Finally, some important applications including photocatalytic degradation of pollutants, photocatalytic H2 production and photocatalytic CO2 reduction are reviewed. A thorough assessment of the progress made in photocatalysis may open new opportunities in designing highly effective hierarchical photocatalysts for advanced applications ranging from thermal catalysis, separation and purification processes to solar cells.

  1. The Antibacterial Polyamide 6-ZnO Hierarchical Nanofibers Fabricated by Atomic Layer Deposition and Hydrothermal Growth

    Science.gov (United States)

    Wang, Zhengduo; Zhang, Li; Liu, Zhongwei; Sang, Lijun; Yang, Lizhen; Chen, Qiang

    2017-06-01

    In this paper, we report the combination of atomic layer deposition (ALD) with hydrothermal techniques to deposit ZnO on electrospun polyamide 6 (PA 6) nanofiber (NF) surface in the purpose of antibacterial application. The micro- and nanostructures of the hierarchical fibers are characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and scanning transmission electron microscopy (STEM). We find that NFs can grow into "water lily"- and "caterpillar"-like shapes, which depend on the number of ALD cycles and the hydrothermal reaction period. It is believed that the thickness of ZnO seed layer by ALD process and the period in hydrothermal reaction have the same importance in crystalline growth and hierarchical fiber formation. The tests of antibacterial activity demonstrate that the ZnO/PA 6 core-shell composite fabricated by the combination of ALD with hydrothermal are markedly efficient in suppressing bacteria survivorship.

  2. Hierarchical linear modeling of California Verbal Learning Test--Children's Version learning curve characteristics following childhood traumatic head injury.

    Science.gov (United States)

    Warschausky, Seth; Kay, Joshua B; Chi, PaoLin; Donders, Jacobus

    2005-03-01

    California Verbal Learning Test-Children's Version (CVLT-C) indices have been shown to be sensitive to the neurocognitive effects of traumatic brain injury (TBI). The effects of TBI on the learning process were examined with a growth curve analysis of CVLT-C raw scores across the 5 learning trials. The sample with history of TBI comprised 86 children, ages 6-16 years, at a mean of 10.0 (SD=19.5) months postinjury; 37.2% had severe injury, 27.9% moderate, and 34.9% mild. The best-fit model for verbal learning was with a quadratic function. Greater TBI severity was associated with lower rate of acquisition and more gradual deceleration in the rate of acquisition. Intelligence test index scores, previously shown to be sensitive to severity of TBI, were positively correlated with rate of acquisition. Results provide evidence that the CVLT-C learning slope is not a simple linear function and further support for specific effects of TBI on verbal learning. ((c) 2005 APA, all rights reserved).

  3. Systemic inflammation, growth factors, and linear growth in the setting of infection and malnutrition.

    Science.gov (United States)

    DeBoer, Mark D; Scharf, Rebecca J; Leite, Alvaro M; Férrer, Alessandra; Havt, Alexandre; Pinkerton, Relana; Lima, Aldo A; Guerrant, Richard L

    2017-01-01

    Deficits in weight gain and linear growth are seen frequently among children in areas where malnutrition and recurrent infections are common. Although both inflammation and malnutrition can result in growth hormone (GH) resistance, the interrelationships of infection, inflammation, and growth deficits in developing areas remain unclear. The aim of this study was to evaluate relationships between low levels of systemic inflammation, growth factors, and anthropometry in a case-control cohort of underweight and normal weight children in northern Brazil. We evaluated data from 147 children ages 6 to 24 mo evaluated in the MAL-ED (Interactions of Malnutrition and Enteric Disease) case-control study following recruitment from a nutrition clinic for impoverished families in Fortaleza, Brazil. We used nonparametric tests and linear regression to evaluate relationships between current symptoms of infections (assessed by questionnaire), systemic inflammation (assessed by high-sensitivity C-reactive protein [hsCRP]), the GH insulin-like growth factor-1 (IGF-1) axis, and measures of anthropometry. All models were adjusted for age and sex. Children with recent symptoms of diarrhea, cough, and fever (compared with those without symptoms) had higher hsCRP levels; those with recent diarrhea and fever also had lower IGF-1 and higher GH levels. Stool myeloperoxidase was positively associated with serum hsCRP. hsCRP was in turn positively associated with GH and negatively associated with IGF-1 and IGF-binding protein-3 (IGFBP-3), suggesting a state of GH resistance. After adjustment for hsCRP, IGF-1 and IGFBP-3 were positively and GH was negatively associated with Z scores for height and weight. Infection and inflammation were linked to evidence of GH resistance, whereas levels of GH, IGF-1, and IGFBP-3 were associated with growth indices independent of hsCRP. These data implicate complex interrelationships between infection, nutritional status, GH axis, and linear growth in

  4. Growth of hierarchical based ZnO micro/nanostructured films and their tunable wettability behavior

    Science.gov (United States)

    Suresh Kumar, P.; Dhayal Raj, A.; Mangalaraj, D.; Nataraj, D.; Ponpandian, N.; Li, Lin; Chabrol, G.

    2011-05-01

    Hierarchical zinc oxide (ZnO) micro/nanostructured thin films were grown onto as-prepared and different annealed ZnO seed layer films by a simple two step chemical process. A cost effective successive ionic layer adsorption and reaction (SILAR) method was employed to grow the seed layer films at optimal temperature (80 °C) and secondly, different hierarchical based ZnO structured thin films were deposited over the seed layered films by chemical bath deposition (CBD). The influence of seed layer on the structural, surface morphological, optical and wettability behavior of the ZnO thin films were systematically investigated. The XRD analysis confirms the high crystalline nature of both the seed layer and corresponding ZnO micro/nanostructured films with a perfect hexagonal structure oriented along (0 0 2) direction. The surface morphology revels a complex and orientated hierarchical based ZnO structured films with diverse shapes from plates to hexagonal rod-like crystal to tube-like structure and even much more complex needle-like shapes during secondary nucleation, by changing the seed layer conditions. The water contact angle (WCA) measurements on hierarchical ZnO structured films are completely examined to study its surface wettability behavior for its suitability in future self-cleaning application. Photoluminescence (PL) spectra of the ZnO structured film exhibit UV and visible emissions in the range of 420-500 nm. The present approach demonstrates its potential for low-temperature, large-scale, controlled synthesis of crystalline hierarchical ZnO nanostructures films.

  5. Controlled synthesis, growth mechanism and highly efficient solar photocatalysis of nitrogen-doped bismuth subcarbonate hierarchical nanosheets architectures.

    Science.gov (United States)

    Dong, Fan; Sun, Yanjuan; Ho, Wing-Kei; Wu, Zhongbiao

    2012-07-21

    The synthesis and self-assembly of hierarchical architectures from nanoscale building blocks with unique morphology, orientation and dimension have opened up new opportunities to enhance their functional performances and remain a great challenge. This work represents tunable synthesis of various types of 3D monodisperse in situ N-doped (BiO)(2)CO(3) hierarchical architectures composed of 2D single-crystal nanosheets with dominant (001) facets by a one-pot template-free hydrothermal method from bismuth citrate and ammonia solution. Depending on the concentration of ammonia solution, the morphology of N-doped (BiO)(2)CO(3), including dandelion-like, hydrangea-like and peony flower-like microspheres, can be selectively constructed due to different self-assembly patterns of nanosheets. It was revealed that the ammonia played dual roles in the formation of N-doped (BiO)(2)CO(3) architectures. One is to hydrolyze bismuth citrate, and the other is to behave as a nitrogen doping source. The in situ doped nitrogen substituted for oxygen in (BiO)(2)CO(3) and subsequently narrowed the band gap, making N-doped (BiO)(2)CO(3) visible light active. Due to the special nanosheets architectures, the prepared various N-doped (BiO)(2)CO(3) materials exhibited especially efficient photocatalytic activity and high durability for the removal of NO in air under both visible and UV light irradiation. Based on the direct observation of the growth process with respect to phase structure, chemical composition and morphological structure, a novel growth mechanism is revealed, which involves a unique multistep pathway, including reaction-nucleation, aggregation, crystallization, dissolution-recrystallization, and Ostwald ripening. The facile synthesis approach and the proposed growth mechanism could provide new insights into the design and controlled synthesis of inorganic hierarchical materials with new or enhanced properties.

  6. Biomimetic hierarchical growth and self-assembly of hydroxyapatite/titania nanocomposite coatings and their biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Nathanael, A. Joseph, E-mail: ajosephnc@yahoo.com [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Im, Young Min [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Oh, Tae Hwan, E-mail: taehwanoh@ynu.ac.kr [Department of Nano, Medical and Polymer Materials, Yeungnam University, Gyeongsan (Korea, Republic of); Yuvakkumar, R. [Department of Nanomaterials Engineering, Chungnam National University, Daejeon (Korea, Republic of); Mangalaraj, D. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore (India)

    2015-03-30

    Graphical abstract: - Highlights: • Novel ‘bowtie’ like biomimetic HA/TiO{sub 2} nanocomposite coatings were prepared. • Simple sol–gel method was used to achieve this novel structure. • Details analysis confirms the formation of bowtie like structure in many ways. • Their functional analysis showed their enhanced activity for biomedical application. - Abstract: This article describes a systematic study of the biomimetic hierarchical growth of hydroxyapatite (HA)/titania (TiO{sub 2}) nanocomposite layered coatings applied by a simple sol–gel dip coating method. Highly stable HA and TiO{sub 2} sols were prepared prior to inducing biomimetic hierarchical growth. Initially, the samples formed a small leaf like structure; however, increasing the dipping cycle resulted in formation of an elongated seed-like structure. Increasing the number of dipping cycles further resulted in a ‘bowtie’ or straw-bale like nanowire structure with a length of 500 nm and a width of 100 nm. Each nanowire like structure had a width of very few nanometers. The crystalline structures, micro/nano structures and surface properties of the coatings were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy respectively. In vitro cellular assays revealed that the growth of the cells in the ‘bowtie’ like structure improved over other samples.

  7. Hierarchical stochastic modeling of large river ecosystems and fish growth across spatio-temporal scales and climate models: the Missouri River endangered pallid sturgeon example

    Science.gov (United States)

    Wildhaber, Mark L.; Wikle, Christopher K.; Moran, Edward H.; Anderson, Christopher J.; Franz, Kristie J.; Dey, Rima

    2017-01-01

    We present a hierarchical series of spatially decreasing and temporally increasing models to evaluate the uncertainty in the atmosphere – ocean global climate model (AOGCM) and the regional climate model (RCM) relative to the uncertainty in the somatic growth of the endangered pallid sturgeon (Scaphirhynchus albus). For effects on fish populations of riverine ecosystems, cli- mate output simulated by coarse-resolution AOGCMs and RCMs must be downscaled to basins to river hydrology to population response. One needs to transfer the information from these climate simulations down to the individual scale in a way that minimizes extrapolation and can account for spatio-temporal variability in the intervening stages. The goal is a framework to determine whether, given uncertainties in the climate models and the biological response, meaningful inference can still be made. The non-linear downscaling of climate information to the river scale requires that one realistically account for spatial and temporal variability across scale. Our down- scaling procedure includes the use of fixed/calibrated hydrological flow and temperature models coupled with a stochastically parameterized sturgeon bioenergetics model. We show that, although there is a large amount of uncertainty associated with both the climate model output and the fish growth process, one can establish significant differences in fish growth distributions between models, and between future and current climates for a given model.

  8. Exploring survey participation, data combination, and research validity in a substance use study: an application of hierarchical linear modeling.

    Science.gov (United States)

    Orsi, Rebecca; Chapman, Phillip L; Edwards, Ruth W

    2010-01-01

    A sound decision regarding combination of datasets is critical for research validity. Data were collected between 1996 and 2000 via a 99-item survey of substance use behaviors. Two groups of 7th-12th grade students in predominately White communities are compared: 166,578 students from 193 communities with high survey participation and 41,259 students from 65 communities with lower participation. Hierarchical logistic models are used to explore whether the two datasets may be combined for further study of community-level substance use effects. "Scenario analysis" is introduced. Results suggest the datasets may reasonably be combined. Limitations and further research are discussed.

  9. Non-compliance with growth hormone treatment in children is common and impairs linear growth.

    Directory of Open Access Journals (Sweden)

    Wayne S Cutfield

    Full Text Available BACKGROUND: GH therapy requires daily injections over many years and compliance can be difficult to sustain. As growth hormone (GH is expensive, non-compliance is likely to lead to suboptimal growth, at considerable cost. Thus, we aimed to assess the compliance rate of children and adolescents with GH treatment in New Zealand. METHODS: This was a national survey of GH compliance, in which all children receiving government-funded GH for a four-month interval were included. Compliance was defined as ≥ 85% adherence (no more than one missed dose a week on average to prescribed treatment. Compliance was determined based on two parameters: either the number of GH vials requested (GHreq by the family or the number of empty GH vials returned (GHret. Data are presented as mean ± SEM. FINDINGS: 177 patients were receiving GH in the study period, aged 12.1 ± 0.6 years. The rate of returned vials, but not number of vials requested, was positively associated with HVSDS (p < 0.05, such that patients with good compliance had significantly greater linear growth over the study period (p<0.05. GHret was therefore used for subsequent analyses. 66% of patients were non-compliant, and this outcome was not affected by sex, age or clinical diagnosis. However, Maori ethnicity was associated with a lower rate of compliance. INTERPRETATION: An objective assessment of compliance such as returned vials is much more reliable than compliance based on parental or patient based information. Non-compliance with GH treatment is common, and associated with reduced linear growth. Non-compliance should be considered in all patients with apparently suboptimal response to GH treatment.

  10. Linear growth of children on a ketogenic diet: does the protein-to-energy ratio matter?

    Science.gov (United States)

    Nation, Judy; Humphrey, Maureen; MacKay, Mark; Boneh, Avihu

    2014-11-01

    Ketogenic diet is a structured effective treatment for children with intractable epilepsy. Several reports have indicated poor linear growth in children on the diet but the mechanism of poor growth has not been elucidated. We aimed to explore whether the protein to energy ratio plays a role in linear growth of children on ketogenic diet. Data regarding growth and nutrition were, retrospectively, collected from the clinical histories of 35 children who were treated with ketogenic diet for at least 6 months between 2002 and 2010. Patients were stratified into groups according to periods of satisfactory or poor linear growth. Poor linear growth was associated with protein or caloric intake of <80% recommended daily intake, and with a protein-to-energy ratio consistently ≤1.4 g protein/100 kcal even when protein and caloric intakes were adequate. We recommend a protein-to-energy ratio of 1.5 g protein/100 kcal be prescribed to prevent growth retardation.

  11. Implicit and Explicit Knowledge of Linear and Exponential Growth in 5- and 9-Year-Olds

    Science.gov (United States)

    Ebersbach, Mirjam; Resing, Wilma C. M.

    2008-01-01

    The present study examined children's implicit and explicit knowledge of linear and non-linear processes. Five- and nine-year-olds (N = 60) were asked to forecast linear and exponential growth by providing the corresponding number of beads. Implicit knowledge was assessed via the magnitudes of the forecasts; explicit knowledge was investigated…

  12. GROWTH ANALYSIS IN RABBIT USING GOMPERTZ NON-LINEAR MODEL

    Directory of Open Access Journals (Sweden)

    A. Setiaji

    2014-10-01

    Full Text Available An experiment was conducted to compare the growth curve of rabbit. Three breeds of rabbit,namely Indonesian Local Rabbit (IL, Flamish Giant (FG and Rex (R were used in the study.Individual body weights of each breed was measured from birth to 63 days of age with 3-days interval.Those periodical data were separated into different sex, be then it was averaged to analysis growthpattern. Growth curve parameters were estimated to fit growth data. There was no difference in bodyweight between sexs within breed. Indonesian local rabbit had the lowest body weight. The resultsshowed that growth curve paramaters among three breeds were significantly different (P<0.05 for bothsexes. FG had the highest value of asymptotic mature weight, followed by R and IL. In conclusion,Gompertz model was excellent fit for the growth data in rabbit with a high coefficient determination (R2= 0.999.

  13. 一类高阶线性系统的分层控制%Hierarchical Control of a Class of High-dimensional Linear Systems

    Institute of Scientific and Technical Information of China (English)

    杨开红; 季海波

    2015-01-01

    近年来,一种基于系统层次结构的分层控制方法发展了起来,它主要针对的是高阶复杂系统。为了分析和控制这类系统,我们首先根据需要构建一个合适的低阶抽象系统,然后在此基础上分析和设计原始系统控制律,即所谓的接口函数。本文将此方法用于一类高阶线性系统的稳定控制问题,并得到了相应的控制律。最后,算例部分的仿真结果说明了这种方法的有效性。%Recently, the hierarchical control method based on a hierarchical architecture has been developed, which is mainly aimed at large-scale complex systems. In order to analyze and control this class of systems, we at first, construct an appropri-ate and low-dimensional abstract system, then synthesize and lift the control law from the obtained abstraction of the original system by the notion of interface function. This paper studies the stable control problem of a class of high-dimensional linear systems and obtains the results by employing the hierarchical control method. Finally, a simulation example is given to illus-trate the effectiveness of this method.

  14. CSR-induced emittance growth in achromats: Linear formalism revisited

    Science.gov (United States)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  15. CSR-induced emittance growth in achromats: Linear formalism revisited

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.

    2015-09-11

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  16. Iron in tubewell water and linear growth in rural Bangladesh.

    Science.gov (United States)

    Briend, A; Hoque, B A; Aziz, K M

    1990-02-01

    The growth of 694 children from rural Bangladesh was studied. Children drinking water containing greater than 1 mg iron/l (n = 628) were significantly taller than those drinking less than 1 mg iron/l (n = 66): their mean (SD) height for age Z score was -2.10 (1.34) compared with -2.45 (1.24), p less than 0.05. This suggests that iron deficiency may contribute to growth retardation in poor communities.

  17. Using hierarchical linear models to test differences in Swedish results from OECD’s PISA 2003: Integrated and subject-specific science education

    Directory of Open Access Journals (Sweden)

    Maria Åström

    2012-06-01

    Full Text Available The possible effects of different organisations of the science curriculum in schools participating in PISA 2003 are tested with a hierarchical linear model (HLM of two levels. The analysis is based on science results. Swedish schools are free to choose how they organise the science curriculum. They may choose to work subject-specifically (with Biology, Chemistry and Physics, integrated (with Science or to mix these two. In this study, all three ways of organising science classes in compulsory school are present to some degree. None of the different ways of organising science education displayed statistically significant better student results in scientific literacy as measured in PISA 2003. The HLM model used variables of gender, country of birth, home language, preschool attendance, an economic, social and cultural index as well as the teaching organisation.

  18. Linear-scaling density-functional simulations of charged point defects in Al2O3 using hierarchical sparse matrix algebra.

    Science.gov (United States)

    Hine, N D M; Haynes, P D; Mostofi, A A; Payne, M C

    2010-09-21

    We present calculations of formation energies of defects in an ionic solid (Al(2)O(3)) extrapolated to the dilute limit, corresponding to a simulation cell of infinite size. The large-scale calculations required for this extrapolation are enabled by developments in the approach to parallel sparse matrix algebra operations, which are central to linear-scaling density-functional theory calculations. The computational cost of manipulating sparse matrices, whose sizes are determined by the large number of basis functions present, is greatly improved with this new approach. We present details of the sparse algebra scheme implemented in the ONETEP code using hierarchical sparsity patterns, and demonstrate its use in calculations on a wide range of systems, involving thousands of atoms on hundreds to thousands of parallel processes.

  19. Effect of milk proteins on linear growth and IGF variables in overweight adolescents

    DEFF Research Database (Denmark)

    Larnkjær, Anni; Arnberg, Karina; Michaelsen, Kim F

    2014-01-01

    Milk may stimulate growth acting via insulin-like growth factor-I (IGF-I) secretion but the effect in adolescents is less examined. This study investigates the effect of milk proteins on linear growth, IGF-I, IGF binding protein-3 (IGFBP-3) and IGF-I/IGFBP-3 ratio in overweight adolescents....

  20. Non-linear Plasma Wake Growth of Electron Holes

    CERN Document Server

    Hutchinson, I H; Zhou, C

    2015-01-01

    An object's wake in a plasma with small Debye length that drifts \\emph{across} the magnetic field is subject to electrostatic electron instabilities. Such situations include, for example, the moon in the solar wind wake and probes in magnetized laboratory plasmas. The instability drive mechanism can equivalently be considered drift down the potential-energy gradient or drift up the density-gradient. The gradients arise because the plasma wake has a region of depressed density and electrostatic potential into which ions are attracted along the field. The non-linear consequences of the instability are analysed in this paper. At physical ratios of electron to ion mass, neither linear nor quasilinear treatment can explain the observation of large-amplitude perturbations that disrupt the ion streams well before they become ion-ion unstable. We show here, however, that electron holes, once formed, continue to grow, driven by the drift mechanism, and if they remain in the wake may reach a maximum non-linearly stable...

  1. Introduction into Hierarchical Matrices

    KAUST Repository

    Litvinenko, Alexander

    2013-12-05

    Hierarchical matrices allow us to reduce computational storage and cost from cubic to almost linear. This technique can be applied for solving PDEs, integral equations, matrix equations and approximation of large covariance and precision matrices.

  2. The effects of oestrogens on linear bone growth

    DEFF Research Database (Denmark)

    Juul, A

    2001-01-01

    boys, and non-aromatizable androgens [oxandrolone or dihydrotestosterone (DHT)] have no effect on GH secretion. Treatment with aromatase inhibitors reduces circulating IGF-I concentrations in healthy males, and reduces growth in boys with testotoxicosis. Taken together, these findings suggest...

  3. GENETIC DEFECTS IN THE GROWTH HORMONE-IGF-I AXIS CAUSING GROWTH HORMONE INSENSITIVITY AND IMPAIRED LINEAR GROWTH

    Directory of Open Access Journals (Sweden)

    Martin O. Savage

    2011-12-01

    Full Text Available Human genetic defects in the growth hormone (GH –IGF-I axis affecting the IGF system present with growth failure as their principal clinical feature. This is usually associated with GH insensitivity (GHI presenting in childhood as severe or mild short stature. Dysmorphic features and metabolic abnormalities may also be present. The field of GHI due to mutations affecting GH action has evolved radidly since the first description of the extreme phenotype related to homozygous GH receptor (GHR mutations in 1966. A continuum of genetic, phenotypic, and biochemical abnormalities can be defined associated with clinically relevant defects in linear growth. The mechanisms of the GH–IGF-I axis in the regulation of normal human growth is discussed followed by descriptions of mutations in GHR, STAT5B, IGF-I, IGFALS, IGF1R and GH1 defects causing bioinactive GH or anti-GH antibodies. These GH-IGF-I axis defects are associated with a range of clinical, and hormonal characteristics. An up-dated approach to the clinical assessment of the patient with GHI focussing on investigation of the GH–IGF-I axis and relevant molecular studies contributing to the identification of causative genetic defects is also discussed.

  4. Effect of O2 pressure on the hydrothermal growth of CuO hierarchical microstructures: characterization and hydrogen adsorption capacity

    Science.gov (United States)

    Roble, M.; Diaz-Droguett, D.

    2017-08-01

    In the present study, the effect of injected O2 pressure to a hydrothermal reactor on the growth, morphology, structure and hydrogen adsorption properties of CuO hierarchical microstructures was investigated. The synthesis consisted of a simple one-step hydrothermal reaction using copper chloride and aqueous ammonia. Hydrothermal reactions were carried at 200 °C at reaction times of 1 and 12 h injecting at the beginning of the synthesis O2 pressures of 0, 30 or 60 bar. The samples were characterized by SEM and EDS for morphological and chemical information, XRD for determination of crystalline phases, lattice parameters and crystallinity grade using Rietveld refinement. Specific surface area was determined using BET method from nitrogen adsorption/desorption isotherm measurements. Hydrogen adsorption capacities at 20 °C were studied for key samples using the quartz crystal microbalance technique under gas exposure pressures between 3 and 100 Torr. It was found that the samples were of monoclinic CuO phase consisting mainly of sphere-like hierarchical microstructures of different average sizes assembled by sheets. The effect of the reactor pressure was mainly seen on average size of the CuO microstructures due to changes in the growth rate, specifically during the first stages of the hydrothermal reaction. Reactor pressure induced changes on the crystallinity of the samples were determined but no correlation was stated. Hydrogen adsorption capacities of studied samples measured at 100 Torr ranged from 0.27 to 0.6 wt%, indicating a good performance as compared with other reported values. Oxygen deficiency in CuO can influence on the hydrogen adsorption capacity.

  5. Abnormal gut integrity is associated with reduced linear growth in rural Malawian children.

    Science.gov (United States)

    Weisz, Ariana J; Manary, Micah J; Stephenson, Kevin; Agapova, Sophia; Manary, Faith G; Thakwalakwa, Chrissie; Shulman, Robert J; Manary, Mark J

    2012-12-01

    The aim of the present study was to investigate the relation of environmental enteropathy, as measured by the dual sugar absorption test, to linear growth faltering in 2- to 5-year-old Malawian children. Dietary quality, food insecurity, anthropometry, and site-specific sugar testing were measured in 418 children, and anthropometry was reassessed 3 months later. A linear regression model predicting linear growth was created. Better growth was associated with less urinary lactulose excretion, more clean water usage, not sleeping with animals, and no previous history of malnutrition. Eighty-seven percent of children studied demonstrated evidence of environmental enteropathy. In conclusion, abnormal gut integrity is associated with reduced linear growth in a population of rural African preschool-age children.

  6. A multilevel excess hazard model to estimate net survival on hierarchical data allowing for non-linear and non-proportional effects of covariates.

    Science.gov (United States)

    Charvat, Hadrien; Remontet, Laurent; Bossard, Nadine; Roche, Laurent; Dejardin, Olivier; Rachet, Bernard; Launoy, Guy; Belot, Aurélien

    2016-08-15

    The excess hazard regression model is an approach developed for the analysis of cancer registry data to estimate net survival, that is, the survival of cancer patients that would be observed if cancer was the only cause of death. Cancer registry data typically possess a hierarchical structure: individuals from the same geographical unit share common characteristics such as proximity to a large hospital that may influence access to and quality of health care, so that their survival times might be correlated. As a consequence, correct statistical inference regarding the estimation of net survival and the effect of covariates should take this hierarchical structure into account. It becomes particularly important as many studies in cancer epidemiology aim at studying the effect on the excess mortality hazard of variables, such as deprivation indexes, often available only at the ecological level rather than at the individual level. We developed here an approach to fit a flexible excess hazard model including a random effect to describe the unobserved heterogeneity existing between different clusters of individuals, and with the possibility to estimate non-linear and time-dependent effects of covariates. We demonstrated the overall good performance of the proposed approach in a simulation study that assessed the impact on parameter estimates of the number of clusters, their size and their level of unbalance. We then used this multilevel model to describe the effect of a deprivation index defined at the geographical level on the excess mortality hazard of patients diagnosed with cancer of the oral cavity. Copyright © 2016 John Wiley & Sons, Ltd.

  7. The growth of disks and bulges during hierarchical galaxy formation. I: fast evolution vs secular processes

    CERN Document Server

    Tonini, Chiara; Croton, Darren J; Wyithe, J Stuart B

    2016-01-01

    We present a theoretical model for the evolution of mass, angular momentum and size of galaxy disks and bulges, and we implement it into the semi-analytic galaxy formation code SAGE. The model follows both secular and violent evolutionary channels, including smooth accretion, disk instabilities, minor and major mergers. We find that the combination of our recipe with hierarchical clustering produces two distinct populations of bulges: merger-driven bulges, akin to classical bulges and ellipticals, and instability-driven bulges, akin to secular (or pseudo-)bulges. The model can successfully reproduce the mass-size relation of gaseous and stellar disks, the evolution of the mass-size relation of ellipticals, the Faber-Jackson relation, and the magnitude-colour diagram of classical and secular bulges. The model predicts only a small overlap of merger-driven and instability-driven components in the same galaxy, and predicts different bulge types as a function of galaxy mass and disk fraction. Bulge type also affe...

  8. Non-linear pattern formation in bone growth and architecture.

    Science.gov (United States)

    Salmon, Phil

    2014-01-01

    The three-dimensional morphology of bone arises through adaptation to its required engineering performance. Genetically and adaptively bone travels along a complex spatiotemporal trajectory to acquire optimal architecture. On a cellular, micro-anatomical scale, what mechanisms coordinate the activity of osteoblasts and osteoclasts to produce complex and efficient bone architectures? One mechanism is examined here - chaotic non-linear pattern formation (NPF) - which underlies in a unifying way natural structures as disparate as trabecular bone, swarms of birds flying, island formation, fluid turbulence, and others. At the heart of NPF is the fact that simple rules operating between interacting elements, and Turing-like interaction between global and local signals, lead to complex and structured patterns. The study of "group intelligence" exhibited by swarming birds or shoaling fish has led to an embodiment of NPF called "particle swarm optimization" (PSO). This theoretical model could be applicable to the behavior of osteoblasts, osteoclasts, and osteocytes, seeing them operating "socially" in response simultaneously to both global and local signals (endocrine, cytokine, mechanical), resulting in their clustered activity at formation and resorption sites. This represents problem-solving by social intelligence, and could potentially add further realism to in silico computer simulation of bone modeling. What insights has NPF provided to bone biology? One example concerns the genetic disorder juvenile Pagets disease or idiopathic hyperphosphatasia, where the anomalous parallel trabecular architecture characteristic of this pathology is consistent with an NPF paradigm by analogy with known experimental NPF systems. Here, coupling or "feedback" between osteoblasts and osteoclasts is the critical element. This NPF paradigm implies a profound link between bone regulation and its architecture: in bone the architecture is the regulation. The former is the emergent

  9. Fatigue crack growth simulations of 3-D linear elastic cracks under thermal load by XFEM

    Institute of Scientific and Technical Information of China (English)

    Himanshu PATHAK[1; Akhilendra SINGH[2; I.V. SINGH[3; S. K. YADAV[3

    2015-01-01

    This paper deals with the fatigue crack growth simulations of three-dimensional linear elastic cracks by XFEM under cyclic thermal load. Both temperature and displacement approximations are extrinsically enriched by Heaviside and crack front enrichment functions. Crack growth is modelled by successive linear extensions, and the end points of these linear extensions are joined by cubic spline segments to obtain a modified crack front. Different crack geometries such as planer, non-planer and arbitrary spline shape cracks are simulated under thermal shock, adiabatic and isothermal loads to reveal the sturdiness and versatility of the XFEM approach.

  10. Hierarchical classification strategy for Phenotype extraction from epidermal growth factor receptor endocytosis screening

    NARCIS (Netherlands)

    L. Cao (Lu); M. Graauw (Marjo de); K. Yan (Kuan); L.C.J. Winkel (Leah C.J.); F.J. Verbeek (Fons)

    2016-01-01

    textabstractBackground: Endocytosis is regarded as a mechanism of attenuating the epidermal growth factor receptor (EGFR) signaling and of receptor degradation. There is increasing evidence becoming available showing that breast cancer progression is associated with a defect in EGFR endocytosis. In

  11. A Bayesian Hierarchical Selection Model for Academic Growth with Missing Data

    Science.gov (United States)

    Allen, Jeff

    2017-01-01

    Using a sample of schools testing annually in grades 9-11 with a vertically linked series of assessments, a latent growth curve model is used to model test scores with student intercepts and slopes nested within school. Missed assessments can occur because of student mobility, student dropout, absenteeism, and other reasons. Missing data…

  12. Growth rate controlled synthesis of hierarchical Bi2S3/In2S3 core/shell microspheres with enhanced photocatalytic activity

    Science.gov (United States)

    Zhou, Juan; Tian, Guohui; Chen, Yajie; Shi, Yunhan; Tian, Chungui; Pan, Kai; Fu, Honggang

    2014-02-01

    Core/shell heterostructure composite has great potential applications in photocatalytic field because the introduction of core can remarkably improve charge transport and enhance the electron-hole separation. Herein, hierarchical Bi2S3/In2S3 core/shell structured microspheres were prepared via a simple one-pot hydrothermal process based on different growth rate of the two kinds of sulphides. The results showed that, the as-prepared hierarchical Bi2S3/In2S3 core/shell heterostructure exhibits significant visible light photocatalytic activity for degradation of 2, 4-dichlorophenol. The introduction of Bi2S3 core can not only improve charge transport and enhance the electron-hole separation, but also broaden the visible light response. The hierarchical porous folwer-like shell of In2S3 could increase the specific surface area and remarkably enhanced the chemical stability of Bi2S3 against oxidation.

  13. Between-session and within-session habituation in Prolonged Exposure Therapy for posttraumatic stress disorder: a hierarchical linear modeling approach.

    Science.gov (United States)

    Sripada, Rebecca K; Rauch, Sheila A M

    2015-03-01

    Prolonged Exposure Therapy is a frontline intervention for posttraumatic stress disorder, but the mechanisms underlying its efficacy are not fully understood. Previous research demonstrates that between- and within-session habituation of fear during exposure is associated with treatment outcome, but these calculations are historically performed with summary statistics such as mean subjective units of distress (SUDS). This question could be better assessed with an analytic technique that uses all SUDS measurements available within sessions. Hierarchical linear modeling was used to investigate the impact of treatment response on SUDS nested within therapy sessions nested within 14 patients. Symptom change (t=-2.43, p=.03) and responder status (t=-2.68, p=.02) predicted slope of SUDS across sessions, but did not reliably predict slope of SUDS within-session, indicating that high responders demonstrated differential between- but not within-session habituation. Thus, individuals who show greater habituation between treatment sessions may be more likely to respond to treatment. Published by Elsevier Ltd.

  14. Analyzing Economic Attainment Patterns of Foreign Born Latin American Male Immigrants to The United States: an Example Using Hierarchical Linear Modeling

    Directory of Open Access Journals (Sweden)

    David J. Gotcher

    2001-09-01

    Full Text Available The paper presents the research which examines and endeavors to account for variation in the economic attainments of immigrants to the United States from Latin America, through the use of Hierarchical Linear Modeling. When analyzing this variation, researchers typically choose between two competing explanations. Human capital theory contends that variation in economic attainment is a product of different characteristics of individuals. Social capital theory contends that variation in economic attainment is a product of differences in characteristics of the societies from which the workers come. The author's central thesis is that we need not choose between human and social capital theories, that we can rely on both theoretical approaches, that it is an empirical and not a theoretical question how much variation can be explained by one set of factors versus the other. The real problem then is to build an appropriate methodology that allows us to partition the variation in economic attainments, identifying how much is explained by individual and how much by group characteristics. Using a multi-level modeling technique, this research presents such a methodology.

  15. The influences of cognitive appraisal, physical injury, coping strategy, and forgiveness of others on PTSD symptoms in traffic accidents using hierarchical linear modeling.

    Science.gov (United States)

    Hyun, Myoung-Ho; Bae, Sung-Man

    2017-09-01

    The purpose of this study was to identify how physical injury, perceived threat, forgiveness of others, and problem-focused coping influence the change of posttraumatic stress disorder (PTSD) symptoms. One hundred twenty patients who had experienced a traumatic vehicle accident participated in 1 to 2 months after the accident; 70 of these people involved at 6 months after the accident. We used a hierarchical linear model analysis to verify the impacts of predictors on change of PTSD symptoms as time passed. The results showed that PTSD symptoms decreased over time, and greater perceived threat would worsen PTSD symptoms and more forgiveness would decrease PTSD symptoms. On the other hand problem-focused coping and physical injury severity were not significantly related to the PTSD symptoms. Specifically, greater perceived threat was found to be related with a deceleration of the decrease in PTSD symptoms, whereas greater forgiveness of others was associated with an acceleration of this decrease. However, problem-focused coping and physical injury severity had no influence on the change rate of PTSD symptoms. Cognitive variable could be more important than physical injury to understand PTSD. In addition, forgiveness of other in a traumatic situation needs to be considered as one of coping strategies.

  16. Hierarchical Linear Model Approach to the Determinants of Activities of Daily Living of Chinese Oldest Old at Both Individual and Regional levels

    Institute of Scientific and Technical Information of China (English)

    Yin Deting; Lu Jiehua

    2007-01-01

    Based on the Chinese longitudinal healthy longevity survey conducted in 2002,this paper uses hierarchical linear model(HLM)to make an approach to the possible determinants of activities of daily living(ADL)of Chinese oldest old(aged 80 and above)by combining both individual and provincial level factors.The descriptive analysis shows that there is a great differential in ADL by province among Chinese oldest old.The findings turn out that there does exist a significant differential in ADL between oldest old and young old,and that there is also a great differential in ADL by province among Chinese oldest old.The HLM demonstrates that comorbidity,age,cognitive impairment,visual impairment,and emotion could be the most important individual factors while natural environment,medical facilities,type of staple food and poverty rate in urban areas are the most significantly regional determinants of ADL of oldest old.The findings imply that future actions should not only be taken at individual level,but also at regional level in order to achieve the goal of a healthy aging society in China.

  17. Non-linear growth analysis of Sumatera thin tail sheep and its cross breds

    Directory of Open Access Journals (Sweden)

    Agus Suparyanto

    2001-12-01

    Full Text Available Growth curve is a figure of individual ability to express its genetic potential to maximum size under the existingenvironmental condition. Three non-linear growth curves, von Bertalanffy, Logistic and Gompertz, were used to analyze the weight-age relationship for five genotypes of sheep. The data were collected from IP2TP Sei Putih, North Sumatera. Num ber of animals which were collected consisted of five genotypes i.e, indigenous Sumatera (n=275, St. Croix (n=571, St. Croix Cross (n=899, Barbados Blackbelly Cross (n=471 and composite (n=740. The three non-linear growth curves were compared to obtain the most suitable curve for describing the shape of growth curves among sheep genotypes. The growth curves of von Bertalanffy fitted better than the others. The results showed that regression parameters of B or M (integral constante were significantly different (P0.05. The data show that there was correlation between A and k.

  18. Efficent Estimation of the Non-linear Volatility and Growth Model

    OpenAIRE

    2009-01-01

    Ramey and Ramey (1995) introduced a non-linear model relating volatility to growth. The solution of this model by generalised computer algorithms for non-linear maximum likelihood estimation encounters the usual difficulties and is, at best, tedious. We propose an algebraic solution for the model that provides fully efficient estimators and is elementary to implement as a standard ordinary least squares procedure. This eliminates issues such as the ‘guesstimation’ of initial values and mul...

  19. Growth of Hierarchically Structured High-Surface Area Alumina on FeCrAl Alloy Wires

    Directory of Open Access Journals (Sweden)

    Chandni Rallan

    2013-01-01

    Full Text Available The formation of metastable alumina phases due to the oxidation of commercial FeCrAl alloy wires (0.5 mm thickness at various temperatures and time periods has been examined. Samples were isothermally oxidised in air using a thermogravimetric analyzer (TGA. The morphology of the oxidised samples was analyzed using an Electronic Scanning Electron Microscope (ESEM and X-ray on the surface analysis was done using an Energy Dispersive X-Ray (EDX analyzer. The technique of X-Ray Diffraction (XRD was used to characterize the phase of the oxide growth. The entire study showed that it was possible to grow high-surface area gamma alumina on the FeCrAl alloy wire surfaces when isothermally oxidised above 800°C over several hours.

  20. Quiescent Sox2+ Cells Drive Hierarchical Growth and Relapse in Sonic Hedgehog Subgroup Medulloblastoma

    Science.gov (United States)

    Vanner, Robert J.; Remke, Marc; Gallo, Marco; Selvadurai, Hayden J.; Coutinho, Fiona; Lee, Lilian; Kushida, Michelle; Head, Renee; Morrissy, Sorana; Zhu, Xueming; Aviv, Tzvi; Voisin, Veronique; Clarke, Ian D.; Li, Yisu; Mungall, Andrew J.; Moore, Richard A.; Ma, Yussanne; Jones, Steven J.M.; Marra, Marco A.; Malkin, David; Northcott, Paul A.; Kool, Marcel; Pfister, Stefan M.; Bader, Gary; Hochedlinger, Konrad; Korshunov, Andrey; Taylor, Michael D.; Dirks, Peter B.

    2015-01-01

    SUMMARY Functional heterogeneity within tumors presents a significant therapeutic challenge. Here we show that quiescent, therapy-resistant Sox2+ cells propagate sonic hedgehog subgroup medulloblastoma by a mechanism that mirrors a neurogenic program. Rare Sox2+ cells produce rapidly cycling doublecortin+ progenitors that, together with their postmitotic progeny expressing NeuN, comprise tumor bulk. Sox2+ cells are enriched following anti-mitotic chemotherapy and Smoothened inhibition, creating a reservoir for tumor regrowth. Lineage traces from Sox2+ cells increase following treatment, suggesting that this population is responsible for relapse. Targeting Sox2+ cells with the antineoplastic mithramycin abrogated tumor growth. Addressing functional heterogeneity and eliminating Sox2+ cells presents a promising therapeutic paradigm for treatment of sonic hedgehog subgroup medulloblastoma. PMID:24954133

  1. Hierarchical LiFePO4 with a controllable growth of the (010) facet for lithium-ion batteries.

    Science.gov (United States)

    Guo, Binbin; Ruan, Hongcheng; Zheng, Cheng; Fei, Hailong; Wei, Mingdeng

    2013-09-27

    Hierarchically structured LiFePO4 was successfully synthesized by ionic liquid solvothermal method. These hierarchically structured LiFePO4 samples were constructed from nanostructured platelets with their (010) facets mainly exposed. To the best of our knowledge, facet control of a hierarchical LiFePO4 crystal has not been reported yet. Based on a series of experimental results, a tentative mechanism for the formation of these hierarchical structures was proposed. After these hierarchically structured LiFePO4 samples were coated with a thin carbon layer and used as cathode materials for lithium-ion batteries, they exhibited excellent high-rate discharge capability and cycling stability. For instance, a capacity of 95% can be maintained for the LiFePO4 sample at a rate as high as 20 C, even after 1000 cycles.

  2. Hierarchical Factor Structure of the Turkish Version of the Posttraumatic Growth Inventory in a Normal Population

    Directory of Open Access Journals (Sweden)

    Mucahit Kagan

    2012-10-01

    Full Text Available Background: Negative consequences of traumatic experiences, such as depression, anxiety, or dissociative symptoms, etc. have been reported by many researchers. However, it is proposed that stressful events not only lead to poor psychological outcomes but also may trigger positive changes. Several instruments gauging posttraumatic benefits have been developed to examine the effects of factors that may promote positive psychological outcomes in the aftermath of stressful events. The Posttraumatic Growth Inventory (PTGI is one of the prominent instruments that assess posttraumatic positive changes. In this study we aimed to assess psychometric properties of the Turkish version of the PTGI. Method: This study differed to an extent from previous studies concerning the features of the PTGI. We used a dispositional form of the instrument in a sample recruited from high school and university students. Our data were collected from 723 volunteers. 367 subjects were males (50.76% and 356 subjects were females (49.24%. Also we did not specify any selection criteria in recruiting subjects owing to their adverse life experiences with a presumption that stressful life events are not uncommon in normal population. We administered to participants a dispositional form of the Posttraumatic Growth Inventory and the Personal View Survey-III. Item statistics for the measure were computed. We performed an explanatory factor analysis by using principal components with promax rotation and a confirmatory factor analysis by using structural equation modeling. Since the factor inter-correlations were higher than .40 we computed Schmid-Leiman transformation to obtain second-order general factor loadings. Inner consistencies and 15-day test-retest intracorrelations were calculated. Results: Item discrimination indexes ranged from .28 to .72. Promax rotated principal components analysis pointed out a three-factor structure. It was found in model testing with structural

  3. The Non-Linear Effect of Corporate Taxes on Economic Growth

    Directory of Open Access Journals (Sweden)

    Huňady Ján

    2015-03-01

    Full Text Available The paper deals with the problem of taxation and its potential impact on economic growth and presents some new empirical insights into this topic. The main aim of the paper is to verify an assumed nonlinear impact of corporate tax rates on economic growth. Based on the theory of public finance and taxation, we hypothesize that at relatively low tax rates it is possible that the impact of taxation on economic growth become slightly positive. On the other hand when the tax rates are higher a negative impact of taxation on economic growth could be expected. Despite the fact that the most of the existing studies find a negative linear relationship between these variables, we can also find strong support for a non-linear relationship from several theoretical models as well as some empirical studies. Based on panel data fixed-effects econometric models, we, as well, find empirical evidence for a non-linear relationship between nominal and effective corporate tax rates and economic growth. Our data consists of annual observations for the period 1999 to 2011 for EU Member States. Based on the results, we also estimated the optimal level of the corporate tax rate in terms of maximizing economic growth in the average of the EU countries.

  4. Tourism and Economic Growth in South Africa: Evidence from Linear and Nonlinear Cointegration Frameworks

    Directory of Open Access Journals (Sweden)

    Andrew Phiri

    2016-03-01

    Full Text Available NorthWest University, South Africa Abstract: Tourism is increasingly being recognized as an essential component of economic growth in South Africa. The purpose of this study is to examine cointegration and causal effects between tourism and economic growth in South Africa for annual data collected between 1995 and 2014. To this end, the paper contrasts two empirical approaches; (1 Engle and Granger (1987 linear cointegration framework, and (2 Enders and Granger (1998 nonlinear cointegration framework. Furthermore, two empirical measures of tourism development are used in the study, namely; tourist receipts and number of international tourist arrivals. The empirical results of the linear framework supports the tourism-led growth hypothesis when tourist receipts are used as a measure of tourismdevelopment.However, the nonlinear framework depicts bi-directional causality between tourist receipts and economic growth. Also, the linear framework supports the economic growth-driven-tourism-hypothesis for tourist arrivals whereas the nonlinear framework depicts no causality between tourist arrivals and economic growth.

  5. Incorporating Endmember Variability into Linear Unmixing of Coarse Resolution Imagery: Mapping Large-Scale Impervious Surface Abundance Using a Hierarchically Object-Based Spectral Mixture Analysis

    Directory of Open Access Journals (Sweden)

    Chengbin Deng

    2015-07-01

    Full Text Available As an important indicator of anthropogenic impacts on the Earth’s surface, it is of great necessity to accurately map large-scale urbanized areas for various science and policy applications. Although spectral mixture analysis (SMA can provide spatial distribution and quantitative fractions for better representations of urban areas, this technique is rarely explored with 1-km resolution imagery. This is due mainly to the absence of image endmembers associated with the mixed pixel problem. Consequently, as the most profound source of error in SMA, endmember variability has rarely been considered with coarse resolution imagery. These issues can be acute for fractional land cover mapping due to the significant spectral variations of numerous land covers across a large study area. To solve these two problems, a hierarchically object-based SMA (HOBSMA was developed (1 to extrapolate local endmembers for regional spectral library construction; and (2 to incorporate endmember variability into linear spectral unmixing of MODIS 1-km imagery for large-scale impervious surface abundance mapping. Results show that by integrating spatial constraints from object-based image segments and endmember extrapolation techniques into multiple endmember SMA (MESMA of coarse resolution imagery, HOBSMA improves the discriminations between urban impervious surfaces and other land covers with well-known spectral confusions (e.g., bare soil and water, and particularly provides satisfactory representations of urban fringe areas and small settlements. HOBSMA yields promising abundance results at the km-level scale with relatively high precision and small bias, which considerably outperforms the traditional simple mixing model and the aggregated MODIS land cover classification product.

  6. Degree Growth, Linear Independence and Periods of a Class of Rational Dynamical Systems

    CERN Document Server

    Ostafe, Alina

    2011-01-01

    We introduce and study algebraic dynamical systems generated by triangular systems of rational functions. We obtain several results about the degree growth and linear independence of iterates as well as about possible lengths of trajectories generated by such dynamical systems over finite fields. Some of these results are generalisations of those known in the polynomial case, some are new even in this case.

  7. Understanding Linear and Exponential Growth: Searching for the Roots in 6- To 9-Year-Olds

    Science.gov (United States)

    Ebersbach, Mirjam; Van Dooren, Wim; Van den Noortgate, Wim; Resing, Wilma C. M.

    2008-01-01

    Previous studies have suggested that children as young as 9 years old have developed an understanding of non-linear growth processes prior to formal education. The present experiment aimed at investigating this competency in even younger samples (i.e., in kindergartners, first, and third graders, ages 6, 7 and 9, respectively). Children (N=90)…

  8. Growth mechanism and photocatalytic activity of self-organized N-doped (BiO)₂CO₃ hierarchical nanosheet microspheres from bismuth citrate and urea.

    Science.gov (United States)

    Dong, Fan; Xiong, Ting; Wang, Rui; Sun, Yanjuan; Jiang, Yanke

    2014-05-14

    Synthesis of nano-/microstructured functional materials with 3D hierarchical microspheres structure has provided new opportunities for optimizing their physical and chemical properties. This work revealed a new growth mechanism of self-organized N-doped (BiO)2CO3 hierarchical microspheres which were fabricated by hydrothermal treatment of bismuth citrate and urea without an additive. Based on time-dependent observation, several evolution processes were believed to account for the formation of the self-organized N-doped (BiO)2CO3 hierarchical microspheres. Initially, crystallized (BiO)4CO3(OH)2 particles were formed during the nucleation and crystallization processes. Subsequently, the intermediate (BiO)4CO3(OH)2 reacted with CO3(2-) to generate (BiO)2CO3 growth nuclei on the surface of the CO2 bubbles which can act as heterogeneous nucleation centers. Next, the (BiO)2CO3 growth nuclei aggregated together after the consumption of CO2 bubbles with the increased concentration of OH(-) and further grew to be nanosheets. The microspheres constructed by small nanosheets further grew with the consumption of small particles. Finally, all (BiO)4CO3(OH)2 transformed to the (BiO)2CO3 phase, accompanied by the doping of N element into the lattice of (BiO)2CO3, and thereby, the well-defined N-doped (BiO)2CO3 hierarchical microspheres were shaped. Depending on the distance between neighboring CO2 bubbles, the resulting microspheres can be linked or dispersed. Besides, the gradual release of CO2 bubbles and CO3(2-) played a crucial role in controlling the nucleation and growth process, resulting in different sizes of microspheres. The fabricated N-doped (BiO)2CO3 hierarchical microspheres displayed admirably efficient and durable photocatalytic activity under both UV and visible light towards removal of NO, which is mainly attributed to the introduction of N element and the special hierarchical structure. This work provides new insights into the controlled synthesis of

  9. The transition towards immortality: non-linear autocatalytic growth of citations to scientific papers

    CERN Document Server

    Golosovsky, Michael

    2013-01-01

    We discuss microscopic mechanisms of complex network growth, with the special emphasis of how these mechanisms can be evaluated from the measurements on real networks. As an example we consider the network of citations to scientific papers. Contrary to common belief that its growth is determined by the linear preferential attachment, our microscopic measurements show that it is driven by the nonlinear autocatalytic growth. This invalidates the scale-free hypothesis for the citation network. The nonlinearity is responsible for a dramatic dynamical phase transition: while the citation lifetime of majority of papers is 6-10 years, the highly-cited papers have practically infinite lifetime.

  10. The Transition Towards Immortality: Non-linear Autocatalytic Growth of Citations to Scientific Papers

    Science.gov (United States)

    Golosovsky, Michael; Solomon, Sorin

    2013-04-01

    We discuss microscopic mechanisms of complex network growth, with the special emphasis of how these mechanisms can be evaluated from the measurements on real networks. As an example we consider the network of citations to scientific papers. Contrary to common belief that its growth is determined by the linear preferential attachment, our microscopic measurements show that it is driven by the nonlinear autocatalytic growth. This invalidates the scale-free hypothesis for the citation network. The nonlinearity is responsible for a dramatic dynamical phase transition: while the citation lifetime of majority of papers is 6-10 years, the highly-cited papers have practically infinite lifetime.

  11. RTA beam dynamics experiments: Limiting cumulative transverse instability growth in a linear periodic system

    Science.gov (United States)

    Houck, Tim; Lidia, Steve; Westenskow, Glen

    2001-05-01

    A critical issue for a Two-Beam accelerator based upon extended relativistic klystrons is controlling the cumulative dipole instability growth. We describe a theoretical scheme to reduce the growth from an exponential to a more manageable linear rate, and a new experiment to test this concept. The experiment utilizes a 1-MeV, 600-Amp, 200-ns electron beam and a short beamline of periodically spaced RF dipole pillbox cavities and solenoid magnets for transport. Descriptions of the RTA injector and the planned beamline are presented, followed by theoretical studies of the beam transport and dipole mode growth.

  12. Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines.

    Science.gov (United States)

    Grajeda, Laura M; Ivanescu, Andrada; Saito, Mayuko; Crainiceanu, Ciprian; Jaganath, Devan; Gilman, Robert H; Crabtree, Jean E; Kelleher, Dermott; Cabrera, Lilia; Cama, Vitaliano; Checkley, William

    2016-01-01

    Childhood growth is a cornerstone of pediatric research. Statistical models need to consider individual trajectories to adequately describe growth outcomes. Specifically, well-defined longitudinal models are essential to characterize both population and subject-specific growth. Linear mixed-effect models with cubic regression splines can account for the nonlinearity of growth curves and provide reasonable estimators of population and subject-specific growth, velocity and acceleration. We provide a stepwise approach that builds from simple to complex models, and account for the intrinsic complexity of the data. We start with standard cubic splines regression models and build up to a model that includes subject-specific random intercepts and slopes and residual autocorrelation. We then compared cubic regression splines vis-à-vis linear piecewise splines, and with varying number of knots and positions. Statistical code is provided to ensure reproducibility and improve dissemination of methods. Models are applied to longitudinal height measurements in a cohort of 215 Peruvian children followed from birth until their fourth year of life. Unexplained variability, as measured by the variance of the regression model, was reduced from 7.34 when using ordinary least squares to 0.81 (p linear mixed-effect models with random slopes and a first order continuous autoregressive error term. There was substantial heterogeneity in both the intercept (p linear regression equation for both estimation and prediction of population- and individual-level growth in height. We show that cubic regression splines are superior to linear regression splines for the case of a small number of knots in both estimation and prediction with the full linear mixed effect model (AIC 19,352 vs. 19,598, respectively). While the regression parameters are more complex to interpret in the former, we argue that inference for any problem depends more on the estimated curve or differences in curves rather

  13. In-situ observation for growth of hierarchical metal-organic frameworks and their self-sequestering mechanism for gas storage

    Science.gov (United States)

    Hyo Park, Jung; Min Choi, Kyung; Joon Jeon, Hyung; Jung Choi, Yoon; Ku Kang, Jeung

    2015-07-01

    Although structures with the single functional constructions and micropores were demonstrated to capture many different molecules such as carbon dioxide, methane, and hydrogen with high capacities at low temperatures, their feeble interactions still limit practical applications at room temperature. Herein, we report in-situ growth observation of hierarchical pores in pomegranate metal-organic frameworks (pmg-MOFs) and their self-sequestering storage mechanism, not observed for pristine MOFs. Direct observation of hierarchical pores inside the pmg-MOF was evident by in-situ growth X-ray measurements while self-sequestering storage mechanism was revealed by in-situ gas sorption X-ray analysis and molecular dynamics simulations. The results show that meso/macropores are created at the early stage of crystal growth and then enclosed by micropore crystalline shells, where hierarchical pores are networking under self-sequestering mechanism to give enhanced gas storage. This pmg-MOF gives higher CO2 (39%) and CH4 (14%) storage capacity than pristine MOF at room temperature, in addition to fast kinetics with robust capacity retention during gas sorption cycles, thus giving the clue to control dynamic behaviors of gas adsorption.

  14. Transition from exponential to linear photoautotrophic growth changes the physiology of Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Schuurmans, R M; Matthijs, J C P; Hellingwerf, K J

    2017-04-01

    Phototrophic microorganisms like cyanobacteria show growth curves in batch culture that differ from the corresponding growth curves of chemotrophic bacteria. Instead of the usual three phases, i.e., lag-, log-, and stationary phase, phototrophs display four distinct phases. The extra growth phase is a phase of linear, light-limited growth that follows the exponential phase and is often ignored as being different. Results of this study demonstrate marked growth phase-dependent alterations in the photophysiology of the cyanobacterium Synechocystis sp. PCC 6803 between cells harvested from the exponential and the linear growth phase. Notable differences are a gradual shift in the energy transfer of the light-harvesting phycobilisomes to the photosystems and a distinct change in the redox state of the plastoquinone pool. These differences will likely affect the result of physiological studies and the efficiency of product formation of Synechocystis in biotechnological applications. Our study also demonstrates that the length of the period of exponential growth can be extended by a gradually stronger incident light intensity that matches the increase of the cell density of the culture.

  15. Comparing non-linear mathematical models to describe growth of different animals

    Directory of Open Access Journals (Sweden)

    Jhony Tiago Teleken

    2017-02-01

    Full Text Available The main objective of this study was to compare the goodness of fit of five non-linear growth models, i.e. Brody, Gompertz, Logistic, Richards and von Bertalanffy in different animals. It also aimed to evaluate the influence of the shape parameter on the growth curve. To accomplish this task, published growth data of 14 different groups of animals were used and four goodness of fit statistics were adopted: coefficient of determination (R2, root mean square error (RMSE, Akaike information criterion (AIC and Bayesian information criterion (BIC. In general, the Richards growth equation provided better fits to experimental data than the other models. However, for some animals, different models exhibited better performance. It was obtained a possible interpretation for the shape parameter, in such a way that can provide useful insights to predict animal growth behavior.

  16. Linear growth and nonlinear saturation of proton ring-driven instabilities in the inner magnetosphere: Linear theory and PIC simulations

    Science.gov (United States)

    Min, K.; Liu, K.; Gary, S. P.

    2015-12-01

    In the inner magnetosphere, the energy-dependent convection of ring current ions can lead to the ring-type proton velocity distributions with ∂fp(vperp)/∂vperp > 0 and ring speeds around the Alfvén speed. This ring-type velocity distribution is known to drive fast magnetosonic waves at propagation quasi-perpendicular to the background magnetic field B0 and, with sufficient temperature anisotropy, electromagnetic ion cyclotron (EMIC) waves at propagation parallel to B0. While there is an abundant literature on linear theory and computer simulations of EMIC waves driven by bi-Maxwellian ion distributions, the literature on the instabilities associated with ring-type proton velocity distributions in the inner magnetosphere is less substantial. Even less studied is the interplay of the two instabilities which lead to the growth of EMIC and fast magnetosonic waves, respectively. The goal of this paper is to provide a comprehensive picture of the instabilities responsible for the two types of waves and their interplay in the conditions of the inner magnetosphere, using linear dispersion theory and self-consistent particle-in-cell (PIC) simulations. For systematic analyses, two-component proton distributions fp = fr + fb are used, where fr represents a tenuous energetic proton velocity distribution with ∂fr(vperp)/∂vperp > 0 providing free energy and fb represents a dense Maxwellian background with sufficiently small beta corresponding to the inner magnetospheric condition. Both an ideal velocity ring and a partial shell with sinn-type pitch angle dependence will be considered for the fr component.

  17. Mechanical picture of the linear transient growth of vortical perturbations in incompressible smooth shear flows

    Science.gov (United States)

    Chagelishvili, George; Hau, Jan-Niklas; Khujadze, George; Oberlack, Martin

    2016-08-01

    The linear dynamics of perturbations in smooth shear flows covers the transient exchange of energies between (1) the perturbations and the basic flow and (2) different perturbations modes. Canonically, the linear exchange of energies between the perturbations and the basic flow can be described in terms of the Orr and the lift-up mechanisms, correspondingly for two-dimensional (2D) and three-dimensional (3D) perturbations. In this paper the mechanical basis of the linear transient dynamics is introduced and analyzed for incompressible plane constant shear flows, where we consider the dynamics of virtual fluid particles in the framework of plane perturbations (i.e., perturbations with plane surfaces of constant phase) for the 2D and 3D case. It is shown that (1) the formation of a pressure perturbation field is the result of countermoving neighboring sets of incompressible fluid particles in the flow, (2) the keystone of the energy exchange mechanism between the basic flow and perturbations is the collision of fluid particles with the planes of constant pressure in accordance with the classical theory of elastic collision of particles with a rigid wall, making the pressure field the key player in this process, (3) the interplay of the collision process and the shear flow kinematics describes the transient growth of plane perturbations and captures the physics of the growth, and (4) the proposed mechanical picture allows us to reconstruct the linearized Euler equations in spectral space with a time-dependent shearwise wave number, the linearized Euler equations for Kelvin modes. This confirms the rigor of the presented analysis, which, moreover, yields a natural generalization of the proposed mechanical picture of the transient growth to the well-established linear phenomenon of vortex-wave-mode coupling.

  18. The Relationship between Economic Growth and Money Laundering – a Linear Regression Model

    Directory of Open Access Journals (Sweden)

    Daniel Rece

    2009-09-01

    Full Text Available This study provides an overview of the relationship between economic growth and money laundering modeled by a least squares function. The report analyzes statistically data collected from USA, Russia, Romania and other eleven European countries, rendering a linear regression model. The study illustrates that 23.7% of the total variance in the regressand (level of money laundering is “explained” by the linear regression model. In our opinion, this model will provide critical auxiliary judgment and decision support for anti-money laundering service systems.

  19. Local Lyapunov exponents sublimiting growth rates of linear random differential equations

    CERN Document Server

    Siegert, Wolfgang

    2009-01-01

    Establishing a new concept of local Lyapunov exponents the author brings together two separate theories, namely Lyapunov exponents and the theory of large deviations. Specifically, a linear differential system is considered which is controlled by a stochastic process that during a suitable noise-intensity-dependent time is trapped near one of its so-called metastable states. The local Lyapunov exponent is then introduced as the exponential growth rate of the linear system on this time scale. Unlike classical Lyapunov exponents, which involve a limit as time increases to infinity in a fixed system, here the system itself changes as the noise intensity converges, too.

  20. Economic growth and energy consumption revisited. Evidence from linear and nonlinear Granger causality

    Energy Technology Data Exchange (ETDEWEB)

    Chiou-Wei, Song Zan [Department of Managerial Economics, Nan-Hua University, Chia-Yi (China); Chen, Ching-Fu [Department of Transportation and Communication Management Science, National Cheng Kung University, 1, Ta-Hsueh Road, Tainan, 701 (China); Zhu, Zhen [Department of Economics, College of Business, University of Central Oklahoma, Edmon, OK, 43034 (United States)

    2008-11-15

    The relationship between energy consumption and economic growth is considered as an imperative issue in energy economics. Previous studies have ignored the nonlinear behavior which could be caused by structural breaks. In this study, both linear and nonlinear Granger causality tests are applied to examine the causal relationship between energy consumption and economic growth for a sample of Asian newly industrialized countries as well as the U.S. This study finds evidence supporting a neutrality hypothesis for the United States, Thailand, and South Korea. However, empirical evidence on Philippines and Singapore reveals a unidirectional causality running from economic growth to energy consumption while energy consumption may have affected economic growth for Taiwan, Hong Kong, Malaysia and Indonesia. Policy implications are also discussed. (author)

  1. Growth of self-organized hierarchical ZnO nanoarchitectures by a simple In/In2S3 controlled thermal evaporation process.

    Science.gov (United States)

    Shen, Guozhen; Bando, Yoshio; Lee, Cheol-Jin

    2005-06-02

    Novel hierarchical ZnO nanoarchitectures, such as microtrepangs, microbelts, nanoflowers, nanocombs, nanowheels, and nanofans assembled by ZnO nanocones, nanobowling pins, nanobottles, nanoarrows, and nanonails, have had their growth controlled by the thermal evaporation of Zn and a mixture of In and In2S3. Both the morphologies of the products and their construction units could be efficiently controlled by simple adjustment of the weight ratio of In/In2S3. The phase structure, morphologies, and photoluminescence properties of the ZnO products were investigated by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and photoluminescence spectroscopy. These novel hierarchical ZnO nanoarchitectures may be attractive building blocks for creating optical or other nanodevices.

  2. Fuzzy inference systems with no any base and linearly parameter growth

    Institute of Scientific and Technical Information of China (English)

    Shitong WANG; Korris F. L. CHUNG; Jieping LU; Bin HAN; Dewen HU

    2004-01-01

    A class of new fuzzy inference systems New-FISs is presented. Compared with the standard fuzzy system,New-FIS is still a universal approximator and has no fuzzy rule base and linearly parameter growth. Thus, it effectively overcomes the second "curse of dimensionality": there is an exponential growth in the number of parameters of a fuzzy system as the number of input variables, resulting in surprisingly reduced computational complexity and being especially suitable for applications, where the complexity is of the first importance with respect to the approximation accuracy.

  3. Linear and nonlinear causality between sectoral electricity consumption and economic growth. Evidence from Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Cheng-Lang, Yang; Chang, Chih-Heng [Department of Managerial Economics, Nanhua University, Chiayi 62102 (China); Lin, Hung-Pin [Department of International Business and Trade, Shu-Te University, Kaohsiung 82445 (China)

    2010-11-15

    This study investigates the linear and nonlinear causality between the total electricity consumption (TEC) and real gross domestic production (RGDP). Unlike previous literature, we solve the undetermined relation between RGDP and electricity consumption by classifying TEC into industrial sector consumption (ISC) and residential sector consumption (RSC) as well as investigating how TEC, ISC, and RSC influence Taiwan's RGDP. By using the Granger's linear causality test, it is shown that (1) there is a bidirectional causality among TEC, ISC, and RGDP, but a neutrality between RSC and RGDP with regard to the linear causality and (2) there is still a bidirectional causality between TEC and RGDP, but a unidirectional causality between RSC and RGDP with regard to the nonlinear causality. On the basis of (1) and (2), we suggest that the electricity policy formulators loosen the restriction on ISC and limit RSC in order to achieve the goal of economic growth. (author)

  4. Linear and nonlinear causality between sectoral electricity consumption and economic growth: Evidence from Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Cheng-Lang [Department of Managerial Economics, Nanhua University, Chiayi 62102, Taiwan (China); Lin, Hung-Pin, E-mail: lhp0606@stu.edu.t [Department of International Business and Trade, Shu-Te University, Kaohsiung 82445, Taiwan (China); Chang, Chih-Heng [Department of Managerial Economics, Nanhua University, Chiayi 62102, Taiwan (China)

    2010-11-15

    This study investigates the linear and nonlinear causality between the total electricity consumption (TEC) and real gross domestic production (RGDP). Unlike previous literature, we solve the undetermined relation between RGDP and electricity consumption by classifying TEC into industrial sector consumption (ISC) and residential sector consumption (RSC) as well as investigating how TEC, ISC, and RSC influence Taiwan's RGDP. By using the Granger's linear causality test, it is shown that (i) there is a bidirectional causality among TEC, ISC, and RGDP, but a neutrality between RSC and RGDP with regard to the linear causality and (ii) there is still a bidirectional causality between TEC and RGDP, but a unidirectional causality between RSC and RGDP with regard to the nonlinear causality. On the basis of (i) and (ii), we suggest that the electricity policy formulators loosen the restriction on ISC and limit RSC in order to achieve the goal of economic growth.

  5. Controllable growth of polyaniline nanowire arrays on hierarchical macro/mesoporous graphene foams for high-performance flexible supercapacitors

    Science.gov (United States)

    Yu, Pingping; Zhao, Xin; Li, Yingzhi; Zhang, Qinghua

    2017-01-01

    Free-standing hierarchical macro/mesoporous flexible graphene foam have been constructed by rational intergration ofwell dispersed graphene oxide sheets and amino-modified polystyrene (PS) spheres through a facile ;templating and embossing; technique. The three dimensional (3D) macro/mesoporous flexible graphene foam not only inherits the uniform porous structures of graphene foam, but also contains hierarchical macro/mesopores on the struts by sacrificing PS spheres and the activation of KOH, which could providing rapid pathways for ionic and electronic transport to high specific capacitance. Vertically polyaniline (PANI) nanowire arrays are then uniformly deposited onto the hierarchical macro/mesoporous graphene foam(fRGO-F/PANI) by a simple in situ polymerization, which show a high specific capacitance of 939 F g-1. Thanks to the synergistic function of 3D bicontinuous hierarchical porous structure of graphene foam and effective immobilization of PANI nanowires on the struts, the assembled symmetric supercapctior with fRGO-F/PANI as electrodes exhibits a maximum energy density and power density of 20.9 Wh kg-1 and 103.2 kW kg-1, respectively. Moreover, it also displays an excellent cyclic stability with a 88.7% retention after 5000 cycles.

  6. A Linear Programming Approach for Modeling and Simulation of Growth and Lipid Accumulation of Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    Clemens Posten

    2013-10-01

    Full Text Available The unicellular microalga Phaeodactylum tricornutum exhibits the ability to accumulate triacylglycerols to a high specific content when nutrients are limited in the culture medium. Therefore, the organism is a promising candidate for biodiesel production. Mathematical modeling can substantially contribute to process development and optimization of algae cultivation on different levels. In our work we describe a linear programming approach to model and simulate the growth and storage molecule accumulation of P. tricornutum. The model is based on mass and energy balances and shows that the organism realizes the inherent drive for maximization of energy to biomass conversion and growth. The model predicts that under nutrient limiting conditions both storage carbohydrates and lipids are synthesized simultaneously but at different rates. The model was validated with data gained from batch growth experiments.

  7. Linear surface roughness growth and flow smoothening in a three-dimensional biofilm model

    Science.gov (United States)

    Head, D. A.

    2013-09-01

    The sessile microbial communities known as biofilms exhibit varying architectures as environmental factors are varied, which for immersed biofilms includes the shear rate of the surrounding flow. Here we modify an established agent-based biofilm model to include affine flow and employ it to analyze the growth of surface roughness of single-species, three-dimensional biofilms. We find linear growth laws for surface geometry in both horizontal and vertical directions and measure the thickness of the active surface layer, which is shown to anticorrelate with roughness. Flow is shown to monotonically reduce surface roughness without affecting the thickness of the active layer. We argue that the rapid roughening is due to nonlocal surface interactions mediated by the nutrient field, which are curtailed when advection competes with diffusion. We further argue the need for simplified models to elucidate the underlying mechanisms coupling flow to growth.

  8. Growth kinetics and toxicity of Enterobacter cloacae grown on linear alkylbenzene sulfonate as sole carbon source.

    Science.gov (United States)

    Khleifat, Khaled M; Tarawneh, Khaled A; Ali Wedyan, Mohammad; Al-Tarawneh, Amjad A; Al Sharafa, Khalid

    2008-10-01

    A successful attempt was made to isolate linear alkylbenzene sulfonate (LAS)-degrading bacteria from soil irrigated with wastewater. The isolated bacteria were able to use LAS as sole carbon and energy source. Maximum growth rates on LAS reached only 0.27 h(-1). 16S-rRNA sequencing and fatty-acid analysis placed the bacteria in the genus Enterobacter cloacae. The growth curves of E. cloacae both in the presence of and the absence of LAS were monitored using measurements of optical density at 600 nm in two different media, nutrient broth and M9 minimal medium, and were modeled mathematically. Growth in NB fit the Riccati and Voltera models, indicating that LAS is not toxic to E. cloacae cells. However, growth of E. cloacae in LAS-containing MM fit the Riccati and Voltera models, whereas growth in LAS-free MM fit the Riccati model only. Furthermore, the kinetic data shown were modeled by Monod's, Andrew's, and Tessier's specific growth rate equations, coupled with the rate of consumption of different concentrations of LAS as sole carbon and energy source, and we determined that Andrew's model best fit these data adequately as a result of the cell-inhibitory effect.

  9. Evaluating Non-Linear Regression Models in Analysis of Persian Walnut Fruit Growth

    Directory of Open Access Journals (Sweden)

    I. Karamatlou

    2016-02-01

    Full Text Available Introduction: Persian walnut (Juglans regia L. is a large, wind-pollinated, monoecious, dichogamous, long lived, perennial tree cultivated for its high quality wood and nuts throughout the temperate regions of the world. Growth model methodology has been widely used in the modeling of plant growth. Mathematical models are important tools to study the plant growth and agricultural systems. These models can be applied for decision-making anddesigning management procedures in horticulture. Through growth analysis, planning for planting systems, fertilization, pruning operations, harvest time as well as obtaining economical yield can be more accessible.Non-linear models are more difficult to specify and estimate than linear models. This research was aimed to studynon-linear regression models based on data obtained from fruit weight, length and width. Selecting the best models which explain that fruit inherent growth pattern of Persian walnut was a further goal of this study. Materials and Methods: The experimental material comprising 14 Persian walnut genotypes propagated by seed collected from a walnut orchard in Golestan province, Minoudasht region, Iran, at latitude 37◦04’N; longitude 55◦32’E; altitude 1060 m, in a silt loam soil type. These genotypes were selected as a representative sampling of the many walnut genotypes available throughout the Northeastern Iran. The age range of walnut trees was 30 to 50 years. The annual mean temperature at the location is16.3◦C, with annual mean rainfall of 690 mm.The data used here is the average of walnut fresh fruit and measured withgram/millimeter/day in2011.According to the data distribution pattern, several equations have been proposed to describesigmoidal growth patterns. Here, we used double-sigmoid and logistic–monomolecular models to evaluate fruit growth based on fruit weight and4different regression models in cluding Richards, Gompertz, Logistic and Exponential growth for evaluation

  10. Investigation of various growth mechanisms of solid tumour growth within the linear-quadratic model for radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    McAneney, H [School of Mathematics and Physics, Queen' s University Belfast, Belfast (United Kingdom); O' Rourke, S F C [School of Mathematics and Physics, Queen' s University Belfast, Belfast (United Kingdom)

    2007-02-21

    The standard linear-quadratic survival model for radiotherapy is used to investigate different schedules of radiation treatment planning to study how these may be affected by different tumour repopulation kinetics between treatments. The laws for tumour cell repopulation include the logistic and Gompertz models and this extends the work of Wheldon et al (1977 Br. J. Radiol. 50 681), which was concerned with the case of exponential re-growth between treatments. Here we also consider the restricted exponential model. This has been successfully used by Panetta and Adam (1995 Math. Comput. Modelling 22 67) in the case of chemotherapy treatment planning.Treatment schedules investigated include standard fractionation of daily treatments, weekday treatments, accelerated fractionation, optimized uniform schedules and variation of the dosage and {alpha}/{beta} ratio, where {alpha} and {beta} are radiobiological parameters for the tumour tissue concerned. Parameters for these treatment strategies are extracted from the literature on advanced head and neck cancer, prostate cancer, as well as radiosensitive parameters. Standardized treatment protocols are also considered. Calculations based on the present analysis indicate that even with growth laws scaled to mimic initial growth, such that growth mechanisms are comparable, variation in survival fraction to orders of magnitude emerged. Calculations show that the logistic and exponential models yield similar results in tumour eradication. By comparison the Gompertz model calculations indicate that tumours described by this law result in a significantly poorer prognosis for tumour eradication than either the exponential or logistic models. The present study also shows that the faster the tumour growth rate and the higher the repair capacity of the cell line, the greater the variation in outcome of the survival fraction. Gaps in treatment, planned or unplanned, also accentuate the differences of the survival fraction given

  11. Investigation of various growth mechanisms of solid tumour growth within the linear-quadratic model for radiotherapy

    Science.gov (United States)

    McAneney, H.; O'Rourke, S. F. C.

    2007-02-01

    The standard linear-quadratic survival model for radiotherapy is used to investigate different schedules of radiation treatment planning to study how these may be affected by different tumour repopulation kinetics between treatments. The laws for tumour cell repopulation include the logistic and Gompertz models and this extends the work of Wheldon et al (1977 Br. J. Radiol. 50 681), which was concerned with the case of exponential re-growth between treatments. Here we also consider the restricted exponential model. This has been successfully used by Panetta and Adam (1995 Math. Comput. Modelling 22 67) in the case of chemotherapy treatment planning.Treatment schedules investigated include standard fractionation of daily treatments, weekday treatments, accelerated fractionation, optimized uniform schedules and variation of the dosage and α/β ratio, where α and β are radiobiological parameters for the tumour tissue concerned. Parameters for these treatment strategies are extracted from the literature on advanced head and neck cancer, prostate cancer, as well as radiosensitive parameters. Standardized treatment protocols are also considered. Calculations based on the present analysis indicate that even with growth laws scaled to mimic initial growth, such that growth mechanisms are comparable, variation in survival fraction to orders of magnitude emerged. Calculations show that the logistic and exponential models yield similar results in tumour eradication. By comparison the Gompertz model calculations indicate that tumours described by this law result in a significantly poorer prognosis for tumour eradication than either the exponential or logistic models. The present study also shows that the faster the tumour growth rate and the higher the repair capacity of the cell line, the greater the variation in outcome of the survival fraction. Gaps in treatment, planned or unplanned, also accentuate the differences of the survival fraction given alternative growth

  12. Urinary osteocalcin and serum pro-C-type natriuretic peptide predict linear catch-up growth in infants

    DEFF Research Database (Denmark)

    Kilpeläinen, Leena; Ivaska, Kaisa K; Kuiri-Hänninen, Tanja;

    2012-01-01

    Preterm (PT) infants are at risk of growth failure despite advanced early care and nutrition. In addition to poor weight gain, slow postnatal linear growth also is associated with adverse neurological outcome. Markers distinguishing infants at risk for impaired catch-up growth are needed. The aim...

  13. Linear Growth and Child Development in Burkina Faso, Ghana, and Malawi.

    Science.gov (United States)

    Prado, Elizabeth L; Abbeddou, Souheila; Adu-Afarwuah, Seth; Arimond, Mary; Ashorn, Per; Ashorn, Ulla; Brown, Kenneth H; Hess, Sonja Y; Lartey, Anna; Maleta, Kenneth; Ocansey, Eugenia; Ouédraogo, Jean-Bosco; Phuka, John; Somé, Jérôme W; Vosti, Steve A; Yakes Jimenez, Elizabeth; Dewey, Kathryn G

    2016-08-01

    We aimed to produce quantitative estimates of the associations between 4 domains of child development and linear growth during 3 periods: before birth, early infancy, and later infancy. We also aimed to determine whether several factors attenuated these associations. In 3700 children in Burkina Faso, Ghana, and Malawi, growth was measured several times from birth to age 18 months. At 18 months, language, motor, socioemotional, and executive function development were assessed. In Burkina Faso (n = 1111), personal-social development was assessed rather than the latter 2 domains. Linear growth was significantly associated with language, motor, and personal-social development but not socioemotional development or executive function. For language, the pooled adjusted estimate of the association with length-for-age z score (LAZ) at 6 months was 0.13 ± 0.02 SD, and with ΔLAZ from 6 to 18 months it was 0.11 ± 0.03 SD. For motor, these estimates were 0.16 ± 0.02 SD and 0.22 ± 0.03 SD, respectively. In 1412 children measured at birth, estimates of the association with LAZ at birth were similar (0.07-0.16 SD for language and 0.09-0.18 SD for motor development). These associations were weaker or absent in certain subsets of children with high levels of developmental stimulation or mothers who received nutritional supplementation. Growth faltering during any period from before birth to 18 months is associated with poor development of language and motor skills. Interventions to provide developmental stimulation or maternal supplementation may protect children who are faltering in growth from poor language and motor development. Copyright © 2016 by the American Academy of Pediatrics.

  14. Describing Growth Pattern of Bali Cows Using Non-linear Regression Models

    Directory of Open Access Journals (Sweden)

    Mohd. Hafiz A.W

    2016-12-01

    Full Text Available The objective of this study was to evaluate the best fit non-linear regression model to describe the growth pattern of Bali cows. Estimates of asymptotic mature weight, rate of maturing and constant of integration were derived from Brody, von Bertalanffy, Gompertz and Logistic models which were fitted to cross-sectional data of body weight taken from 74 Bali cows raised in MARDI Research Station Muadzam Shah Pahang. Coefficient of determination (R2 and residual mean squares (MSE were used to determine the best fit model in describing the growth pattern of Bali cows. Von Bertalanffy model was the best model among the four growth functions evaluated to determine the mature weight of Bali cattle as shown by the highest R2 and lowest MSE values (0.973 and 601.9, respectively, followed by Gompertz (0.972 and 621.2, respectively, Logistic (0.971 and 648.4, respectively and Brody (0.932 and 660.5, respectively models. The correlation between rate of maturing and mature weight was found to be negative in the range of -0.170 to -0.929 for all models, indicating that animals of heavier mature weight had lower rate of maturing. The use of non-linear model could summarize the weight-age relationship into several biologically interpreted parameters compared to the entire lifespan weight-age data points that are difficult and time consuming to interpret.

  15. The Linear Growth of Structure in the R_h=ct Universe

    CERN Document Server

    Melia, Fulvio

    2016-01-01

    We use recently published redshift space distortion measurements of the cosmological growth rate, f sigma_8(z), to examine whether the linear evolution of perturbations in the R_h=ct cosmology is consistent with the observed development of large scale structure. We find that these observations favour R_h=ct over the version of LCDM optimized with the joint analysis of Planck and linear growth rate data, particularly in the redshift range 0 < z < 1, where a significant curvature in the functional form of f sigma_8(z) predicted by the standard model---but not by R_h=ct---is absent in the data. When LCDM is optimized using solely the growth rate measurements, however, the two models fit the observations equally well though, in this case, the low-redshift measurements find a lower value for the fluctuation amplitude than is expected in Planck LCDM. Our results strongly affirm the need for more precise measurements of f sigma_8(z) at all redshifts, but especially at z < 1.

  16. Linear growth and child development in low- and middle-income countries: a meta-analysis.

    Science.gov (United States)

    Sudfeld, Christopher R; McCoy, Dana Charles; Danaei, Goodarz; Fink, Günther; Ezzati, Majid; Andrews, Kathryn G; Fawzi, Wafaie W

    2015-05-01

    The initial years of life are critical for physical growth and broader cognitive, motor, and socioemotional development, but the magnitude of the link between these processes remains unclear. Our objective was to produce quantitative estimates of the cross-sectional and prospective association of height-for-age z score (HAZ) with child development. Observational studies conducted in low- and middle-income countries (LMICs) presenting data on the relationship of linear growth with any measure of child development among children 2 years old (95% CI, 0.05-0.12; I(2) = 78%). Prospectively, each unit increase in HAZ for children ≤ 2 years old was associated with a +0.22-SD increase in cognition at 5 to 11 years after multivariate adjustment (95% CI, 0.17-0.27; I(2) = 0%). HAZ was also significantly associated with earlier walking age and better motor scores (P development. Effective interventions that reduce linear growth restriction may improve developmental outcomes; however, integration with environmental, educational, and stimulation interventions may produce larger positive effects. Copyright © 2015 by the American Academy of Pediatrics.

  17. Long-term linear growth of children with severe steroid-responsive nephrotic syndrome.

    Science.gov (United States)

    Emma, Francesco; Sesto, Antonella; Rizzoni, Gianfranco

    2003-08-01

    The present study was designed to evaluate the risk of permanent linear growth impairment in a selected group of 42 children with steroid-dependent nephrotic syndrome (SDNS) and 14 children with frequently relapsing nephrotic syndrome (FRNS). Longitudinal height measurements were available in all patients from the onset of the disease for a mean follow-up of 11.7+/-3.5 years. During the prepubertal period, patients lost 0.49+/-0.6 height SD score (HtSDS) ( P<0.001). Twenty-three patients have reached their final height with an average loss of 0.92+/-0.8 HtSDS from the onset of their disease ( P<0.001) and 0.68+/-0.7 from their target HtSDS ( P<0.001). The pubertal growth spurt was mildly delayed in male but not female patients. Steroid therapy, calculated as the mean duration of prednisone (PDN) treatment or as the average cumulative PDN dose, was the only predictor of poor growth evolution. Partial catch-up growth occurred after PDN withdrawal. Children with early onset NS and adolescent patients, who were still receiving PDN after the age of 9 years in girls and 11 years in boys, were at higher risk for HtSDS loss. In conclusion, children with severe steroid-responsive NS are at risk of permanent growth retardation secondary to prolonged courses of steroid treatment.

  18. Numerical computation of the linear stability of the diffusion model for crystal growth simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.; Sorensen, D.C. [Rice Univ., Houston, TX (United States); Meiron, D.I.; Wedeman, B. [California Institute of Technology, Pasadena, CA (United States)

    1996-12-31

    We consider a computational scheme for determining the linear stability of a diffusion model arising from the simulation of crystal growth. The process of a needle crystal solidifying into some undercooled liquid can be described by the dual diffusion equations with appropriate initial and boundary conditions. Here U{sub t} and U{sub a} denote the temperature of the liquid and solid respectively, and {alpha} represents the thermal diffusivity. At the solid-liquid interface, the motion of the interface denoted by r and the temperature field are related by the conservation relation where n is the unit outward pointing normal to the interface. A basic stationary solution to this free boundary problem can be obtained by writing the equations of motion in a moving frame and transforming the problem to parabolic coordinates. This is known as the Ivantsov parabola solution. Linear stability theory applied to this stationary solution gives rise to an eigenvalue problem of the form.

  19. Increased linear bone growth by GH in the absence of SOCS2 is independent of IGF-1.

    Science.gov (United States)

    Dobie, Ross; Ahmed, Syed F; Staines, Katherine A; Pass, Chloe; Jasim, Seema; MacRae, Vicky E; Farquharson, Colin

    2015-11-01

    Growth hormone (GH) signaling is essential for postnatal linear bone growth, but the relative importance of GHs actions on the liver and/or growth plate cartilage remains unclear. The importance of liver derived insulin like-growth factor-1 (IGF-1) for endochondral growth has recently been challenged. Here, we investigate linear growth in Suppressor of Cytokine Signaling-2 (SOCS2) knockout mice, which have enhanced growth despite normal systemic GH/IGF-1 levels. Wild-type embryonic ex vivo metatarsals failed to exhibit increased linear growth in response to GH, but displayed increased Socs2 transcript levels (P GH treatment enhanced metatarsal linear growth over a 12 day period. Despite this increase, IGF-1 transcript and protein levels were not increased in response to GH. In accordance with these data, IGF-1 levels were unchanged in GH-challenged postnatal Socs2(-/-) conditioned medium despite metatarsals showing enhanced linear growth. Growth-plate Igf1 mRNA levels were not elevated in juvenile Socs2(-/-) mice. GH did however elevate IGF-binding protein 3 levels in conditioned medium from GH challenged metatarsals and this was more apparent in Socs2(-/-) metatarsals. GH did not enhance the growth of Socs2(-/-) metatarsals when the IGF receptor was inhibited, suggesting that IGF receptor mediated mechanisms are required. IGF-2 may be responsible as IGF-2 promoted metatarsal growth and Igf2 expression was elevated in Socs2(-/-) (but not WT) metatarsals in response to GH. These studies emphasise the critical importance of SOCS2 in regulating GHs ability to promote bone growth. Also, GH appears to act directly on the metatarsals of Socs2(-/-) mice, promoting growth via a mechanism that is independent of IGF-1.

  20. Parallel hierarchical radiosity rendering

    Energy Technology Data Exchange (ETDEWEB)

    Carter, M.

    1993-07-01

    In this dissertation, the step-by-step development of a scalable parallel hierarchical radiosity renderer is documented. First, a new look is taken at the traditional radiosity equation, and a new form is presented in which the matrix of linear system coefficients is transformed into a symmetric matrix, thereby simplifying the problem and enabling a new solution technique to be applied. Next, the state-of-the-art hierarchical radiosity methods are examined for their suitability to parallel implementation, and scalability. Significant enhancements are also discovered which both improve their theoretical foundations and improve the images they generate. The resultant hierarchical radiosity algorithm is then examined for sources of parallelism, and for an architectural mapping. Several architectural mappings are discussed. A few key algorithmic changes are suggested during the process of making the algorithm parallel. Next, the performance, efficiency, and scalability of the algorithm are analyzed. The dissertation closes with a discussion of several ideas which have the potential to further enhance the hierarchical radiosity method, or provide an entirely new forum for the application of hierarchical methods.

  1. Determinantes dos déficits ponderal e de crescimento linear de crianças menores de dois anos Determinants of weight and linear growth deficits in children under two years of age

    Directory of Open Access Journals (Sweden)

    Valterlinda Alves de Oliveira

    2006-10-01

    Full Text Available OBJETIVO: Identificar os determinantes da desnutrição energético-protéica que ocasionam déficits ponderal e de crescimento linear em crianças. MÉTODOS: Estudo transversal envolvendo 1.041 crianças (menores de dois anos de idade de 10 municípios do Estado da Bahia, de 1999 a 2000. Utilizou-se a técnica de regressão logística e estratégia da abordagem hierárquica para identificar os fatores associados ao estado antropométrico. RESULTADOS: O modelo final para déficit no crescimento linear revelou como determinante básico: a posse de dois ou menos equipamentos domésticos (OR=2,9; IC 95%: 1,74-4,90 e no nível subjacente, a ausência de consulta pré-natal (OR=2,7; IC 95%: 1,47-4,97; entre os determinantes imediatos o baixo peso ao nascer (OBJECTIVE: To identify determinants of protein-energy malnutrition resulting in weight and linear growth deficits in children. METHODS: A cross-sectional study was carried out among 1,041 children (under two years of age from 10 municipalities in Bahia, Northeastern Brazil, during 1999-2000. Both logistic regression and a hierarchical approach were used to identify factors associated with the anthropometric measures. RESULTS: The basic determinant found in the final model for linear growth retardation was having up to two household appliances (OR=2.9; 95% CI: 1.74-4.90; as an underlying determinant, not attending prenatal visits (OR=2.7; 95% CI: 1.47-4.97; and, among immediate determinants were low birth weight (OR=3.6; 95% CI: 1.72-7.70 and reported hospitalization within 12 months before the interview (OR=2.4; 95% CI: 1.42-4.10. Determinants of weight deficit at the basic, underlying and immediate levels were: per capita monthly income of less than one-fourth of the minimum wage (OR=3.4; 95% CI: 1.41-8.16, not attending prenatal visits (OR=2.1; 95% CI: 1.03-4.35 and low birth weight (OR=4.8; 95% CI: 2.00-11.48 respectively. CONCLUSIONS: Children's weight and linear deficits were accounted for

  2. Linear surface roughness growth and flow smoothening in a three-dimensional biofilm model

    CERN Document Server

    Head, D A

    2013-01-01

    The sessile microbial communities known as biofilms exhibit different surface structures as environmental factors are varied, including nutrient availability and flow-generated shear stresses. Here we modify an established agent-based biofilm model to include adhesive interactions, permitting it to mechanically react to an imposed stress. This model is employed to analyse the growth of surface roughness of single-species, three-dimensional biofilms. We find linear growth laws of surface geometry in both horizontal and vertical directions, and an active surface layer whose thickness anti-correlates with roughness. Flow is consistently shown to reduce surface roughness without affecting the active layer. We argue that the rapid roughening is due to non-local surface interactions mediated by the nutrient field which are curtailed by sufficiently rapid flows, and suggest simplified models will need to be developed to elucidate the underlying mechanisms.

  3. Effect of linear alkylbenzene sulfonate on population growth of Daphnia galeata: a life table evaluation.

    Science.gov (United States)

    Tanaka, Y; Nakanishi, J

    2001-01-01

    The chronic effect of linear alkylbenzene sulfonate (LAS12) on a daphnid species (Daphnia galeata) was examined by the life table experiment. The estimated responses in the intrinsic rate of population growth r were analyzed with two alternate concentration-response functions, i.e., the power function and the quadratic function. Based on the best-fit power function model with biases corrected by the jackknife procedure, the population-level EC50, which is defined as the concentration of chemicals that reduces the population growth rate (the intrinsic rate of natural increase) by 50%, was estimated as 2.5 mg/L. The 48-h acute immobility test yielded EC50 of 4.6 mg/L. The population-level effect of LAS12 on this test species is considerably more sensitive than the acute lethal effects to neonates.

  4. Homogeneous shear turbulence - bypass concept via interplay of linear transient growth and nonlinear transverse cascade

    Science.gov (United States)

    Mamatsashvili, George; Dong, Siwei; Khujadze, George; Chagelishvili, George; Jiménez, Javier; Foysi, Holger

    2016-04-01

    We performed direct numerical simulations of homogeneous shear turbulence to study the mechanism of the self-sustenance of subcritical turbulence in spectrally stable (constant) shear flows. For this purpose, we analyzed the turbulence dynamics in Fourier/wavenumber/spectral space based on the simulation data for the domain aspect ratio 1 : 1 : 1. Specifically, we examined the interplay of linear transient growth of Fourier harmonics and nonlinear processes. The transient growth of harmonics is strongly anisotropic in spectral space. This, in turn, leads to anisotropy of nonlinear processes in spectral space and, as a result, the main nonlinear process appears to be not a direct/inverse, but rather a transverse/angular redistribution of harmonics in Fourier space referred to as the nonlinear transverse cascade. It is demonstrated that the turbulence is sustained by the interplay of the linear transient, or nonmodal growth and the transverse cascade. This course of events reliably exemplifies the wellknown bypass scenario of subcritical turbulence in spectrally stable shear flows. These processes mainly operate at large length scales, comparable to the box size. Consequently, the central, small wavenumber area of Fourier space (the size of which is determined below) is crucial in the self-sustenance and is labeled the vital area. Outside the vital area, the transient growth and the transverse cascade are of secondary importance - Fourier harmonics are transferred to dissipative scales by the nonlinear direct cascade. The number of harmonics actively participating in the self-sustaining process (i.e., the harmonics whose energies grow more than 10% of the maximum spectral energy at least once during evolution) is quite large - it is equal to 36 for the considered box aspect ratio - and obviously cannot be described by low-order models.

  5. Growth and antioxidant response in Hydrocharis dubis (Bl.) Backer exposed to linear alkylbenzene sulfonate.

    Science.gov (United States)

    Wu, Zhonghua; Yu, Dan; Li, Jinlin; Wu, Gongguo; Niu, Xiaona

    2010-04-01

    A two-week exposure experiment was designed to investigate the toxicity of linear alkylbenzene sulfonate (LAS) on the aquatic plant Hydrocharis dubis (Bl.) Backer, focusing on growth, photosynthetic pigments and the activities of antioxidant enzymes. No significant differences were observed in the growth parameters of H. dubis when H. dubis was exposed to lower LAS doses (10 mg l(-1)) resulted in significant decreases in all growth parameters of H. dubis. No significant effect on pigment contents was observed at up to 50 mg l(-1) LAS, beyond which pigment contents declined gradually. Malondialdehyde (MDA) content did not show obvious differences when H. dubis plants were exposed to growth and physiology of H. dubis when the dose of LAS exceeded 10 mg l(-1) . Therefore, LAS at current environmental concentrations dose not appear to cause evident phytotoxic effects on H. dubis.

  6. Plasma endotoxin core antibody concentration and linear growth are unrelated in rural Malawian children aged 2-5 years

    Science.gov (United States)

    Environmental enteropathy is subclinical inflammation of the upper gastrointestinal tract associated with reduced linear growth in developing countries. Usually investigators have used biopsy or a dual sugar absorption test to assess environmental enteropathy. Such tests are time and resource intens...

  7. The effect of changes in sea surface temperature on linear growth of Porites coral in Ambon Bay

    Energy Technology Data Exchange (ETDEWEB)

    Corvianawatie, Corry, E-mail: corvianawatie@students.itb.ac.id; Putri, Mutiara R., E-mail: mutiara.putri@fitb.itb.ac.id [Oceanography Study Program, Bandung Institute of Technology (ITB), Jl. Ganesha 10 Bandung (Indonesia); Cahyarini, Sri Y., E-mail: yuda@geotek.lipi.go.id [Research Center for Geotechnology, Indonesian Institute of Sciences (LIPI), Bandung (Indonesia)

    2015-09-30

    Coral is one of the most important organisms in the coral reef ecosystem. There are several factors affecting coral growth, one of them is changes in sea surface temperature (SST). The purpose of this research is to understand the influence of SST variability on the annual linear growth of Porites coral taken from Ambon Bay. The annual coral linear growth was calculated and compared to the annual SST from the Extended Reconstructed Sea Surface Temperature version 3b (ERSST v3b) model. Coral growth was calculated by using Coral X-radiograph Density System (CoralXDS) software. Coral sample X-radiographs were used as input data. Chronology was developed by calculating the coral’s annual growth bands. A pair of high and low density banding patterns observed in the coral’s X-radiograph represent one year of coral growth. The results of this study shows that Porites coral extents from 2001-2009 and had an average growth rate of 1.46 cm/year. Statistical analysis shows that the annual coral linear growth declined by 0.015 cm/year while the annual SST declined by 0.013°C/year. SST and the annual linear growth of Porites coral in the Ambon Bay is insignificantly correlated with r=0.304 (n=9, p>0.05). This indicates that annual SST variability does not significantly influence the linear growth of Porites coral from Ambon Bay. It is suggested that sedimentation load, salinity, pH or other environmental factors may affect annual linear coral growth.

  8. Long-term wave growth and its linear and nonlinear interactions with wind fluctuations

    Directory of Open Access Journals (Sweden)

    Z. Ge

    2008-05-01

    Full Text Available Following Ge and Liu (2007, the simultaneously recorded time series of wave elevation and wind velocity are examined for long-term (on Lavrenov's τ4-scale or 3 to 6 h linear and nonlinear interactions between the wind fluctuations and the wave field. Over such long times the detected interaction patterns should reveal general characteristics for the wave growth process. The time series are divided into three episodes, each approximately 1.33 h long, to represent three sequential stages of wave growth. The classic Fourier-domain spectral and bispectral analyses are used to identify the linear and quadratic interactions between the waves and the wind fluctuations as well as between different components of the wave field.

    The results show clearly that as the wave field grows the linear interaction becomes enhanced and covers wider range of frequencies. Two different wave-induced components of the wind fluctuations are identified. These components, one at around 0.4 Hz and the other at around 0.15 to 0.2 Hz, are generated and supported by both linear and quadratic wind-wave interactions probably through the distortions of the waves to the wind field. The fact that the higher-frequency wave-induced component always stays with the equilibrium range of the wave spectrum around 0.4 Hz and the lower-frequency one tends to move with the downshifting of the primary peak of the wave spectrum defines the partition of the primary peak and the equilibrium range of the wave spectrum, a characteristic that could not be revealed by short-time wavelet-based analyses in Ge and Liu (2007. Furthermore, these two wave-induced peaks of the wind spectrum appear to have different patterns of feedback to the wave field. The quadratic wave-wave interactions also are assessed using the auto-bispectrum and are found to be especially active during the first and the third episodes. Such directly detected wind-wave interactions, both linear and

  9. Linear growth patterns in small for gestational age and preterm infants after zinc supplementation

    Directory of Open Access Journals (Sweden)

    Caecilia Nancy Setiawan

    2016-07-01

    Full Text Available Background Low birth weight (LBW infants are at risk for growth disturbances due to intrauterine zinc deficiency. Zinc supplementation is expected to improve the linear growth of LBW babies. Objective To assess the effect of zinc supplementation on linear growth in preterm and small for gestational age (SGA infants. Methods This quasi-experimental study had a pre- and post-test design. Subjects were LBW infants hospitalized in Kariadi Hospital during March-December 2011, consisted of SGA and preterm neonates. All subjects were given 5 mg of zinc syrup daily for 3 months. Subjects’ head circumference, weight, and length were measured monthly. Serum zinc levels were measured before and after supplementation. Data were analyzed with Chi-square test, independent T-test, and general linear model repeated measure. Results A total of 61 subjects were enrolled consisted of 31 preterm and 30 SGA neonates. Mean serum zinc levels in the preterm group were 168.2 (SD 54.5 μg/dL pre-supplementation and 163.6 (SD 50.7 μg/dL post-supplementation (P=0.049, while mean serum zinc levels in the SGA group were 174.8 (SD 46.6 μg/dL pre-supplementation and 167.4 (SD 49.4 μg/dL post-supplementation (P=0.271. Median percentage preterm weight and length increased from 87.3 to 102.4% in the third month (P<0.001 and from 95.8 to 103.9% in the third month (P<0.001, respectively. Median percentage SGA weight and length increased from 73.5 to 98.3% in the third month (P<0.001 and from 94.5 to 102.2% in the third month (P<0.001, respectively. Conclusion Both, the preterm and SGA infants exhibit catch-up growth after three months of zinc supplementation. [

  10. Controlled synthesis of ZnO branched nanorod arrays by hierarchical solution growth and application in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fang Xiaoming, E-mail: cexmfang@scut.edu.cn; Peng Lihua; Shang Xiaoying; Zhang Zhengguo

    2011-07-29

    We demonstrate the controlled synthesis of ZnO branched nanorod arrays on fluorine-doped SnO{sub 2}-coated glass substrates by the hierarchical solution growth method. In the secondary growth, the concentration of Zn(NO{sub 3}){sub 2}/hexamethylenetetramine plays an important role in controlling the morphology of the branched nanorod arrays, besides that of diaminopropane used as a structure-directing agent to induce the growth of branches. The population density and morphology of the branched nanorod arrays depend on those of the nanorod arrays obtained from the primary growth, which can be modulated though the concentration of Zn(NO{sub 3}){sub 2}/hexamethylenetetramine in the primary growth solution. The dye-sensitized ZnO branched nanorod arrays exhibit much stronger optical absorption as compared with its corresponding primary nanorod arrays, suggesting that the addition of the branches improves light harvesting. The dye-sensitized solar cell based on the optimized ZnO branched nanorod array reaches a conversion efficiency of 1.66% under the light radiation of 1000 W/m{sup 2}. The branched nanorod arrays can also be applied in other application fields of ZnO.

  11. Graphene Oxide Templated Growth and Superior Lithium Storage Performance of Novel Hierarchical Co2V2O7 Nanosheets.

    Science.gov (United States)

    Luo, Yanzhu; Xu, Xu; Zhang, Yuxiang; Chen, Chih-Yen; Zhou, Liang; Yan, Mengyu; Wei, Qiulong; Tian, Xiaocong; Mai, Liqiang

    2016-02-01

    Hierarchical Co2V2O7 nanosheets consisted of interconnected nanoparticles are synthesized by a facile method using graphene oxide as the template. The electrochemical reaction mechanism of the Co2V2O7 nanosheets is thoroughly investigated by in situ XRD and ex situ TEM. The initial Co2V2O7 transforms into CoO nanoparticles and vanadium oxides in the first cycle, and the following reversible conversion reaction mainly occurs between CoO and Co and lithiation/delithiation of the vanadium oxides. The Co2V2O7 nanosheet displays a high reversible capacity (962 mAh/g at 0.5 A/g) and remarkable high rate capability. When cycled at 5.0 A/g, a reversible capacity of 441 mAh/g can be retained after 900 cycles. The stable high capacity and excellent rate capability make the hierarchical Co2V2O7 nanosheets a promising anode material for lithium-ion batteries.

  12. Consequences of bounds on longitudinal emittance growth for the design of recirculating linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compaction in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in [1]. Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV.

  13. Ability of non-linear mixed models to predict growth in laying hens

    Directory of Open Access Journals (Sweden)

    Luis Fernando Galeano-Vasco

    2014-11-01

    Full Text Available In this study, the Von Bertalanffy, Richards, Gompertz, Brody, and Logistics non-linear mixed regression models were compared for their ability to estimate the growth curve in commercial laying hens. Data were obtained from 100 Lohmann LSL layers. The animals were identified and then weighed weekly from day 20 after hatch until they were 553 days of age. All the nonlinear models used were transformed into mixed models by the inclusion of random parameters. Accuracy of the models was determined by the Akaike and Bayesian information criteria (AIC and BIC, respectively, and the correlation values. According to AIC, BIC, and correlation values, the best fit for modeling the growth curve of the birds was obtained with Gompertz, followed by Richards, and then by Von Bertalanffy models. The Brody and Logistic models did not fit the data. The Gompertz nonlinear mixed model showed the best goodness of fit for the data set, and is considered the model of choice to describe and predict the growth curve of Lohmann LSL commercial layers at the production system of University of Antioquia.

  14. Crystal growth of an organic non-linear optical material from the vapour phase

    CERN Document Server

    Hou, W

    1999-01-01

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the va...

  15. Fatty acid as structure directing agent for controlled secondary growth of CoFe2O4 nanoparticles to achieve mesoscale assemblies: A facile approach for developing hierarchical structures

    Science.gov (United States)

    Saikia, K.; Kaushik, S. D.; Sen, D.; Mazumder, S.; Deb, P.

    2016-08-01

    Mesoscale hierarchical assemblies have emerged out as a new class of structures between fine dimension nanoparticles and bulk structures, having distinctly different physical properties from either side. Controlling the self-assembly process of primary nanoparticles and subsequent secondary growth mechanism is the key aspect for achieving such ordered structures. In this work, we introduce a new insight on achieving hierarchical assemblies of CoFe2O4 nanoparticles based on the temporal stability of the primary nanoparticles, where, the growth and stability of the primary particles are controlled by using oleic acid. It is found that the developed particles, at a critical concentration of oleic acid, prefer a secondary growth process, rather than promoting their individual growth. Domination of the attractive hydrophobic interaction over steric repulsion among the primary particles at this critical concentration of oleic acid is found to be the key factor for the initial aggregation of the primary particles, which eventually leads to the formation of spherical hierarchical assemblies via oriented attachment. It is also realized that the extremely well or poor stability conditions of the primary particles do not allow this secondary growth process. Estimated values of Co2+ distribution factor show that the cation distribution factor of CoFe2O4 system is not affected by the nature of dominant growth processes, when these are controlled. Interestingly, magnetic measurements reflect the stronger interparticle interaction in the hierarchical system and high magnetic moment values at low magnetic field.

  16. Sphere-shaped hierarchical cathode with enhanced growth of nanocrystal planes for high-rate and cycling-stable li-ion batteries.

    Science.gov (United States)

    Zhang, Linjing; Li, Ning; Wu, Borong; Xu, Hongliang; Wang, Lei; Yang, Xiao-Qing; Wu, Feng

    2015-01-14

    High-energy and high-power Li-ion batteries have been intensively pursued as power sources in electronic vehicles and renewable energy storage systems in smart grids. With this purpose, developing high-performance cathode materials is urgently needed. Here we report an easy and versatile strategy to fabricate high-rate and cycling-stable hierarchical sphered cathode Li(1.2)Ni(0.13)Mn(0.54)Co(0.13)O2, by using an ionic interfusion method. The sphere-shaped hierarchical cathode is assembled with primary nanoplates with enhanced growth of nanocrystal planes in favor of Li(+) intercalation/deintercalation, such as (010), (100), and (110) planes. This material with such unique structural features exhibits outstanding rate capability, cyclability, and high discharge capacities, achieving around 70% (175 mAh g(-1)) of the capacity at 0.1 C rate within about 2.1 min of ultrafast charging. Such cathode is feasible to construct high-energy and high-power Li-ion batteries.

  17. Hierarchical rutile TiO2 flower cluster-based high efficiency dye-sensitized solar cells via direct hydrothermal growth on conducting substrates.

    Science.gov (United States)

    Ye, Meidan; Liu, Hsiang-Yu; Lin, Changjian; Lin, Zhiqun

    2013-01-28

    Dye-sensitized solar cells (DSSCs) based on hierarchical rutile TiO(2) flower clusters prepared by a facile, one-pot hydrothermal process exhibit a high efficiency. Complex yet appealing rutile TiO(2) flower films are, for the first time, directly hydrothermally grown on a transparent conducting fluorine-doped tin oxide (FTO) substrate. The thickness and density of as-grown flower clusters can be readily tuned by tailoring growth parameters, such as growth time, the addition of cations of different valence and size, initial concentrations of precursor and cation, growth temperature, and acidity. Notably, the small lattice mismatch between the FTO substrate and rutile TiO(2) renders the epitaxial growth of a compact rutile TiO(2) layer on the FTO glass. Intriguingly, these TiO(2) flower clusters can then be exploited as photoanodes to produce DSSCs, yielding a power conversion efficiency of 2.94% despite their rutile nature, which is further increased to 4.07% upon the TiCl(4) treatment.

  18. Growth and Zeros of Meromorphic Solutions to Second-Order Linear Differential Equations

    Directory of Open Access Journals (Sweden)

    Maamar Andasmas

    2016-04-01

    Full Text Available The main purpose of this article is to investigate the growth of meromorphic solutions to homogeneous and non-homogeneous second order linear differential equations f00+Af0+Bf = F, where A(z, B (z and F (z are meromorphic functions with finite order having only finitely many poles. We show that, if there exist a positive constants σ > 0, α > 0 such that |A(z| ≥ eα|z|σ as |z| → +∞, z ∈ H, where dens{|z| : z ∈ H} > 0 and ρ = max{ρ(B, ρ(F} < σ, then every transcendental meromorphic solution f has an infinite order. Further, we give some estimates of their hyper-order, exponent and hyper-exponent of convergence of distinct zeros.

  19. Early Weight Gain, Linear Growth, and Mid-Childhood Blood Pressure

    DEFF Research Database (Denmark)

    Perng, Wei; Rifas-Shiman, Sheryl L; Kramer, Michael S;

    2016-01-01

    In recent years, the prevalence of hypertension and prehypertension increased markedly among children and adolescents, highlighting the importance of identifying determinants of elevated blood pressure early in life. Low birth weight and rapid early childhood weight gain are associated with higher...... future blood pressure. However, few studies have examined the timing of postnatal weight gain in relation to later blood pressure, and little is known regarding the contribution of linear growth. We studied 957 participants in Project Viva, an ongoing US prebirth cohort. We examined the relations...... of gains in body mass index z-score and length/height z-score during 4 early life age intervals (birth to 6 months, 6 months to 1 year, 1 to 2 years, and 2 to 3 years) with blood pressure during mid-childhood (6-10 years) and evaluated whether these relations differed by birth size. After accounting...

  20. Synthesis, crystal growth and studies on non-linear optical property of new chalcones

    Science.gov (United States)

    Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

    2006-09-01

    The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

  1. Linear optical studies of metal surfaces: Diffusion, growth, and surface dynamics

    Science.gov (United States)

    Nabighian, Edward Ara

    Through the use of laser-induced thermal desorption, a monolayer density grating is produced on a Ni(111) substrate. Using linear optical diffraction from this grating we monitor surface diffusion. By varying the angular direction of the grating we also monitor the azimuthal dependence of diffusion over 360° rotation. For hydrogen on Ni(111) we measured the diffusion rates from 65 K to 240 K, yielding diffusion rates which vary from 2 × 10 -15 cm2/sec to 2 × 10-7 cm2/sec. The results reveal energies of diffusion in both the classical overbarrier hopping and phonon-assisted quantum regimes. For xenon on Ni(111) we measured the diffusion rates from 30 K to 60 K, yielding diffusion rates which vary from 1.3 × 10-10 cm2/sec to 1 × 10-9 cm2/sec. In the case of xenon diffusion, the results also reveal an unusually low diffusivity. In addition, growth measurements of xenon on Ni(111) were studied from 35 K to 60 K using an optical reflectance difference technique. The growth of xenon was found to change mechanisms as temperature varied. At 35 K xenon grows in 3-dimensional islands (Volmer-Weber growth), at 40 K xenon grows as 2-dimensional islands (Frank van der Merwe growth), and above 60 K xenon grows to a thickness of only one monolayer. We can not only monitor the growth mechanism, but the growth rate as well. Finally we use optical reflectance difference to monitor sputtering and annealing on the Ni(111) substrate. The competing surface roughening of sputtering and surface reordering of annealing was found to follow an Arrhenius form with an activation energy of Ea = 1.1 eV/atom given by direct atom evaporation from step edges. By monitoring the formation of islands and pits on the surface during sputtering at various temperatures we are able to determine that above 823 K the annealing process reorders the surface faster than sputtering can create surface roughness. As temperature decreases we see an increase in island and pit formation due to the lessened

  2. On effects of viscosity and magnetic fields on the largest growth rate of linear Rayleigh-Taylor instability

    Science.gov (United States)

    Jiang, Fei

    2016-11-01

    In this article, we investigate the effect of viscosity on the largest growth rate in the linear Rayleigh-Taylor (RT) instability of a three-dimensional nonhomogeneous incompressible viscous flow in a bounded domain. By adapting a modified variational approach and careful analysis, we show that the largest growth rate in linear RT instability tends to zero as the viscosity coefficient goes to infinity. Moreover, the largest growth rate increasingly converges to one of the corresponding inviscid fluids as the viscosity coefficient goes to zero. Applying these analysis techniques to the corresponding viscous magnetohydrodynamic fluids, we can also show that the largest growth rate in linear magnetic RT instability tends to zero as the strength of horizontal (or vertical) magnetic field increasingly goes to a critical value.

  3. Non-linear growth: The road ahead for Indian IT outsourcing companies

    Directory of Open Access Journals (Sweden)

    Y.L.R. Moorthi

    2011-09-01

    Full Text Available India-centric IT services companies (major among them being the SWITCH companies -- Satyam, Wipro, Infosys, TCS, Cognizant and HCL grew rapidly for more than a decade by providing low cost, high quality business process and IT outsourcing services. With the bigger companies already crossing the 100,000-employee mark, they are now turning their attention to non-linear revenue (i.e. revenue less dependent on the number of employees or greater revenue earned per employee. For this, they need to pursue ‘disruptive’ strategies which are distinctly different from the ‘incremental’ initiatives they adopted in the past to maintain linear revenue. This paper first outlines the disruptive and the incremental initiatives of the SWITCH companies and the road ahead for them. This is followed by an interview with R Chandrasekaran, President and MD, Global Delivery, Cognizant, who discusses Cognizant’s key operating principles – which include customer-centricity, their unique Two-in-a-Box operating model and their emphasis on working together with clients to make their businesses stronger – and how they have contributed to the company’s spectacular growth story.

  4. Geometric and growth rate tests of General Relativity with recovered linear cosmological perturbations

    CERN Document Server

    Wilson, Michael J

    2016-01-01

    I investigate the consistency of the VIMOS Public Extragalactic Redshift Survey v7 galaxy sample with the expansion history and linear growth rate predicted by General Relativity (GR) and a Planck (2015) cosmology. To do so, I measure the redshift-space power spectrum, which is anisotropic due to both redshift-space distortions (RSD) and the Alcock-Paczynski (AP) effect. In Chapter 6, I place constraints of $f \\sigma_8(0.76) = 0.44 \\pm 0.04$ and $f \\sigma_8(1.05) = 0.28 \\pm 0.08$, which remain consistent with GR at 95% confidence. Marginalising over the anisotropic AP effect degrades the constraints by a factor of three but allows $F_{AP} \\equiv (1+z) D_A H/c$ to be simultaneously constrained. The VIPERS v7 joint-posterior on $(f \\sigma_8, F_{AP})$ shows no compelling deviation from GR. Chapter 7 investigates the inclusion of a simple density transform: `clipping' prior to the RSD analysis. This tackles the root-cause of non-linearity and may extend the validity of perturbation theory. Moreover, this marked s...

  5. Linear and nonlinear causality between renewable energy consumption and economic growth in the USA

    Directory of Open Access Journals (Sweden)

    Haiyun Xu

    2016-12-01

    Full Text Available This study aims to investigate Granger causality between renewable energy consumption (REC and economic growth (EG for USA. To accomplish this objective and to add the stronger evidence to the controversial issue, the tests were done under a new framework that embeds wavelet analysis, a novel tool, in nonlinear causality test approaches developed recently. The classical linear causality test procedure was also involved for comparison. The empirical data sources from the USA Energy Information Administration and Economist Intelligence Unit (EIU CountryData database. Sample period is from January 1993 to October 2014. The results indicate significantly the existence of unidirectional causality from EG to REC and support the conservation hypothesis. In additional, further evidences show that the causal relationship among them is not constant and depends on the time scale or frequency ranges, and that wavelet analysis is an important aid to capture the nonlinear causality. This suggests that renewable energy limitations do not seem to damage economic growth. These results have implications of importance for research analysts as well as policy makers of energy economy.

  6. Influence of plant growth on degradation of linear alkylbenzene sulfonate in sludge-amended soil.

    Science.gov (United States)

    Mortensen, G K; Egsgaard, H; Ambus, P; Jensen, E S; Grøn, C

    2001-01-01

    Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the possible accumulation and effects of linear alkylbenzene sulfonate (LAS) in the soil ecosystem. Therefore, we have studied the uptake and degradation of LAS in greenhouse pot experiments. Sewage sludge was incorporated into a sandy soil to give a range from very low to very high applications (0.4 to 90 Mg dry wt. ha(-1)). In addition, LAS was added as water solutions. The soil was transferred to pots and sown with barley (Hordeum vulgare L. cv. Apex), rape (Brassica napus L. cv. Hyola 401), or carrot (Daucus carota L.). Also, plant-free controls were established. For all additions there was no plant uptake above the detection limit at 0.5 mg LAS kg(-1) d.w, but plant growth stimulated the degradation. With a growth period of 30 d, LAS concentrations in soil from pots with rape had dropped from 27 to 1.4 mg kg(-1) dry wt., but in plant-free pots the concentration decreased only to 2.4 mg kg(-1) dry wt. When LAS was added as a spike, the final concentration in soil from planted pots was 0.7 mg kg(-1) dry wt., but in pots without plants the final concentration was much higher (2.5 mg kg(-1) dry wt.). During degradation, the relative fraction of homologues C10, C11, and C12 decreased, while C13 increased.

  7. Linear growth and final height characteristics in adolescent females with anorexia nervosa.

    Directory of Open Access Journals (Sweden)

    Dalit Modan-Moses

    Full Text Available OBJECTIVE: Growth retardation is an established complication of anorexia nervosa (AN. However, findings concerning final height of AN patients are inconsistent. The aim of this study was to assess these phenomena in female adolescent inpatients with AN. METHODS: We retrospectively studied all 211 female adolescent AN patients hospitalized in an inpatient eating disorders department from 1/1/1987 to 31/12/99. Height and weight were assessed at admission and thereafter routinely during hospitalization and follow-up. Final height was measured in 69 patients 2-10 years after discharge. Pre-morbid height data was available in 29 patients. RESULTS: Patients' height standard deviation scores (SDS on admission (-0.285±1.0 and discharge (-0.271±1.02 were significantly (p<0.001 lower than expected in normal adolescents. Patients admitted at age ≤13 years, or less than 1 year after menarche, were more severely growth-impaired than patients admitted at an older age, (p = 0.03. Final height SDS, available for 69 patients, was -0.258±1.04, significantly lower than expected in a normal population (p = 0.04, and was more severely compromised in patients who were admitted less than 1 year from their menarche. In a subgroup of 29 patients with complete growth data (pre-morbid, admission, discharge, and final adult height, the pre-morbid height SDS was not significantly different from the expected (-0.11±1.1, whereas heights at the other time points were significantly (p = 0.001 lower (-0.56±1.2, -0.52±1.2, and -0.6±1.2, respectively. CONCLUSIONS: Our findings suggest that whereas the premorbid height of female adolescent AN patients is normal, linear growth retardation is a prominent feature of their illness. Weight restoration is associated with catch-up growth, but complete catch-up is often not achieved.

  8. Linear Growth and Final Height Characteristics in Adolescent Females with Anorexia Nervosa

    Science.gov (United States)

    Kochavi, Brigitte; Toledano, Anat; Segev, Sharon; Balawi, Fadel; Mitrany, Edith; Stein, Daniel

    2012-01-01

    Objective Growth retardation is an established complication of anorexia nervosa (AN). However, findings concerning final height of AN patients are inconsistent. The aim of this study was to assess these phenomena in female adolescent inpatients with AN. Methods We retrospectively studied all 211 female adolescent AN patients hospitalized in an inpatient eating disorders department from 1/1/1987 to 31/12/99. Height and weight were assessed at admission and thereafter routinely during hospitalization and follow-up. Final height was measured in 69 patients 2–10 years after discharge. Pre-morbid height data was available in 29 patients. Results Patients’ height standard deviation scores (SDS) on admission (−0.285±1.0) and discharge (−0.271±1.02) were significantly (p<0.001) lower than expected in normal adolescents. Patients admitted at age ≤13 years, or less than 1 year after menarche, were more severely growth-impaired than patients admitted at an older age, (p = 0.03). Final height SDS, available for 69 patients, was −0.258±1.04, significantly lower than expected in a normal population (p = 0.04), and was more severely compromised in patients who were admitted less than 1 year from their menarche. In a subgroup of 29 patients with complete growth data (pre-morbid, admission, discharge, and final adult height), the pre-morbid height SDS was not significantly different from the expected (−0.11±1.1), whereas heights at the other time points were significantly (p = 0.001) lower (−0.56±1.2, −0.52±1.2, and −0.6±1.2, respectively). Conclusions Our findings suggest that whereas the premorbid height of female adolescent AN patients is normal, linear growth retardation is a prominent feature of their illness. Weight restoration is associated with catch-up growth, but complete catch-up is often not achieved. PMID:23029058

  9. Understanding uncertainties in non-linear population trajectories: a Bayesian semi-parametric hierarchical approach to large-scale surveys of coral cover.

    Directory of Open Access Journals (Sweden)

    Julie Vercelloni

    Full Text Available Recently, attempts to improve decision making in species management have focussed on uncertainties associated with modelling temporal fluctuations in populations. Reducing model uncertainty is challenging; while larger samples improve estimation of species trajectories and reduce statistical errors, they typically amplify variability in observed trajectories. In particular, traditional modelling approaches aimed at estimating population trajectories usually do not account well for nonlinearities and uncertainties associated with multi-scale observations characteristic of large spatio-temporal surveys. We present a Bayesian semi-parametric hierarchical model for simultaneously quantifying uncertainties associated with model structure and parameters, and scale-specific variability over time. We estimate uncertainty across a four-tiered spatial hierarchy of coral cover from the Great Barrier Reef. Coral variability is well described; however, our results show that, in the absence of additional model specifications, conclusions regarding coral trajectories become highly uncertain when considering multiple reefs, suggesting that management should focus more at the scale of individual reefs. The approach presented facilitates the description and estimation of population trajectories and associated uncertainties when variability cannot be attributed to specific causes and origins. We argue that our model can unlock value contained in large-scale datasets, provide guidance for understanding sources of uncertainty, and support better informed decision making.

  10. Understanding uncertainties in non-linear population trajectories: a Bayesian semi-parametric hierarchical approach to large-scale surveys of coral cover.

    Science.gov (United States)

    Vercelloni, Julie; Caley, M Julian; Kayal, Mohsen; Low-Choy, Samantha; Mengersen, Kerrie

    2014-01-01

    Recently, attempts to improve decision making in species management have focussed on uncertainties associated with modelling temporal fluctuations in populations. Reducing model uncertainty is challenging; while larger samples improve estimation of species trajectories and reduce statistical errors, they typically amplify variability in observed trajectories. In particular, traditional modelling approaches aimed at estimating population trajectories usually do not account well for nonlinearities and uncertainties associated with multi-scale observations characteristic of large spatio-temporal surveys. We present a Bayesian semi-parametric hierarchical model for simultaneously quantifying uncertainties associated with model structure and parameters, and scale-specific variability over time. We estimate uncertainty across a four-tiered spatial hierarchy of coral cover from the Great Barrier Reef. Coral variability is well described; however, our results show that, in the absence of additional model specifications, conclusions regarding coral trajectories become highly uncertain when considering multiple reefs, suggesting that management should focus more at the scale of individual reefs. The approach presented facilitates the description and estimation of population trajectories and associated uncertainties when variability cannot be attributed to specific causes and origins. We argue that our model can unlock value contained in large-scale datasets, provide guidance for understanding sources of uncertainty, and support better informed decision making.

  11. Collaborative Hierarchical Sparse Modeling

    CERN Document Server

    Sprechmann, Pablo; Sapiro, Guillermo; Eldar, Yonina C

    2010-01-01

    Sparse modeling is a powerful framework for data analysis and processing. Traditionally, encoding in this framework is done by solving an l_1-regularized linear regression problem, usually called Lasso. In this work we first combine the sparsity-inducing property of the Lasso model, at the individual feature level, with the block-sparsity property of the group Lasso model, where sparse groups of features are jointly encoded, obtaining a sparsity pattern hierarchically structured. This results in the hierarchical Lasso, which shows important practical modeling advantages. We then extend this approach to the collaborative case, where a set of simultaneously coded signals share the same sparsity pattern at the higher (group) level but not necessarily at the lower one. Signals then share the same active groups, or classes, but not necessarily the same active set. This is very well suited for applications such as source separation. An efficient optimization procedure, which guarantees convergence to the global opt...

  12. 变革型领导与团队成员工作态度:基于多层线性模型的研究%Transformational Leadership and Team Work Attitudes:A Hierarchical Linear Modeling Study

    Institute of Scientific and Technical Information of China (English)

    王桢; 罗正学; 李旭培

    2013-01-01

    This study investigated the relationship among transformational leadership, team satisfaction and team identification, explored the mediating role of team leaning and research the boundary condition of team leadership and team learning. Survey data were collected from 85 customer service teams in high-tech organizations. Hierarchical linear modeling results demonstrated that the relationship between transformational leadership and team satisfaction and identification was partially mediated by team learning. And team member expertise moderated the relationship between transformational leadership and team learning.%本研究探讨团队层面变革型领导与成员团队满意度、团队认同之间的关系,考察团队学习的中介作用,以及影响变革型领导和团队学习关系的权变因素.采用问卷调查方式对某省通讯运营商的85个客服团队进行调查.采用多层线性模型(Hierarchical Linear Modeling)对团队变革型领导、团队学习、团队满意度、团队认同之间的关系进行分析.结果表明,团队学习对团队领导的变革型领导行为与员工工作态度的关系具有一定的中介作用.团队成员工作技能在变革型领导和团队学习间起调节作用.

  13. Facile growth and composition-dependent photocatalytic activity of flowerlike BiOCl1-xBrx hierarchical microspheres

    Science.gov (United States)

    Qin, Qin; Guo, Yingna; Zhou, Dandan; Yang, Yuxin; Guo, Yihang

    2016-12-01

    A group of nanosheet-assembled three-dimensional BiOCl1-xBrx hierarchical microspheres (x = 0, 0.3, 0.4, 0.5, 0.7, 0.8 and 1.0) with layered tetragonal crystal phase were prepared by 2-methoxyethanol-assisted solvothermal route and using ionic liquids as both halogen sources and structure-directing agent. By the combination of the results including XRD, XPS and UV-vis/DR spectra, lattice substitution of halogen atoms each other and then formation of BiOCl1-xBrx solid solution was evidenced. Additionally, the BiOCl1-xBrx microspheres exhibited interesting composition-dependent band gaps. The simulated sunlight and visible-light photocatalytic properties including degradation, mineralization and reusability of the BiOCl1-xBrx microspheres were evaluated by selecting p-nitrophenol (PNP) and tetrabromobisphenol-A (TBBPA) as the target pollutant compounds, finding that the balance between the suitable band gap and adequate potential of the valence band in BiOCl1-xBrx crystals dominated their photocatalytic activity. Additionally, the BiOCl1-xBrx microspheres with advantages such as enhanced photon utilization efficiency, larger BET surface area and favorable (110) exposed reactive surface gave the positive influence on their photocatalytic activity. Based on the results of photoelectrochemistry experiment and indirect chemical probe testing, direct •O2- and hVB+ photooxidation for the decomposition of PNP or TBBPA was revealed.

  14. Alkali-etching growth of nest-like Ag@mTiO2 hierarchical nanostructures and their potential applications.

    Science.gov (United States)

    Zhang, Zongnan; Zhang, Haijiao

    2017-06-01

    Porous nanomaterials have attracted extensive interests in adsorption, catalysis, biosensors, and biomedicine due to their high surface area, well-defined pore structure and tunable pore size. However, how to obtain porous nanomaterials of desirable component and unique structure with multifunctionalities and synergetic properties is still a great challenge. In this work, a novel nest-like Ag@mTiO2 hierarchical nanostructure with Ag nanoparticle as the core and a mesoporous crystalline TiO2 as the protective shell was successfully prepared by layer-by-layer assembly technique and alkali-etching hydrothermal route. By simply changing the conditions of alkali etching, different nanostructures could be obtained, such as core-shell or rattle type. In the process, the thickness of coating silica layer and TiO2 shell both played important roles for the formation of desired nanostructures. The as-prepared products had a large specific surface area of 301m(2)/g and a tailored TiO2 outer shell. Raman spectra results showed perfect SERS signal of the tags enhanced and remained good stability even after one month. Doxycycline (Doxy) was chosen to evaluate their drug loading and controlled release properties. The results indicated that the obtained Ag@mTiO2 nanoparticles exhibited good biocompatibility and excellent drug-loading capacity. Consequently, they are also expected to serve as ideal candidates for more potential applications including photocatalysis, drug controlled release, biosensor and cell imaging, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Hierarchical classification approach for mapping rubber tree growth using per-pixel and object-oriented classifiers with SPOT-5 imagery

    Directory of Open Access Journals (Sweden)

    Hayder Dibs

    2017-06-01

    Full Text Available There has been growing interest in Malaysia to increase the productivity of latex. This made accurate knowledge of rubber tree growth and age distribution a helpful decision making tool for the government, rubber plantation managers, and harvesters. Gathering this information using conventional methods is difficult, time consuming, and limited in spatial coverage. This paper presents hierarchical classification approach to obtain accurate map of rubber tree growth age distribution using SPOT-5 satellite imagery. The objective of the study is to evaluate the performance of pixel-based and object-oriented classifiers for rubber growth classification. At the first level, the general land cover was classified into eight land cover classes (soil, water body, rubber, mature oil palm, young oil palm, forest, urban area, and other vegetation using Mahalanobis distance (MD, k-nearest neighbor (k-NN, and Support Vector Machine (SVM classifiers. Thereafter, the best classification map, k-NN output, was used to select only pixels that belong to the rubber class from the SPOT-5 image. The extracted pixels served as input into the next classification hierarchy where four classifiers, MD, k-NN, SVM, and decision tree (DT, were implemented to map rubber trees into three intra-classes (mature, middle-aged, and young rubbers. The result produced overall accuracy of 97.48%, 96.90%, 96.25%, and 80.80% for k-NN, SVM, MD, and DT respectively. The result indicates that object-oriented classifiers are better than pixel-based methods mapping rubber tree growth.

  16. TOXIC EFFECTS OF LINEAR ALKYLBENZENE SULFONATE, ANTHRACENE AND THEIR MIXTURE ON GROWTH OF A MICROBIAL CONSORTIUM ISOLATED FROM POLLUTED SEDIMENT

    OpenAIRE

    2010-01-01

    The aim of this study was to determine the effect of linear alkylbenzene sulfonate (LAS), anthracene and a LAS-anthracene mixture on the growth of a microbial consortium isolated from polluted sediment. The microbial consortium was grown in a sterile glass bottle with mineral medium containing 1 g/L of glucose. Microbial growth inhibition produced by LAS, anthracene and combinations of LAS and anthracene was determined by viable count in nutritive agar; inhibitory concentration 50 (IC50) was ...

  17. Potential role of IGF-1 z score to predict permanent linear growth impairment in children with IBD.

    Science.gov (United States)

    Lee, Jessica J; Mitchell, Paul D; Hood, Helen C; Grand, Richard J; Cohen, Laurie E

    2014-04-01

    In this pilot study, we analyzed serum insulin-like growth factor 1 (IGF-1)- and IGF-binding protein-3-for-age z scores from 54 inflammatory bowel disease children with no, temporary, or permanent growth impairment. Although our findings did not reach statistical significance, patients with permanent linear growth impairment had lower IGF-1-for-age z scores (-1.76 [-2.25 to -0.43]) compared with those with no or temporary growth impairment (-0.84 [-1.49 to -0.3]) and -1.16 [-1.59 to -1.51], respectively). IGF-binding protein-3 levels were similar across the 3 groups. In the absence of significant inflammation and malnutrition, lower IGF-1-for-age z scores may help distinguish patients likely to have permanent growth impairment from those whose growth impairment is likely to be temporary.

  18. Linear Growth and Fat and Lean Tissue Gain during Childhood: Associations with Cardiometabolic and Cognitive Outcomes in Adolescent Indian Children.

    Directory of Open Access Journals (Sweden)

    Ghattu V Krishnaveni

    Full Text Available We aimed to determine how linear growth and fat and lean tissue gain during discrete age periods from birth to adolescence are related to adolescent cardiometabolic risk factors and cognitive ability.Adolescents born to mothers with normal glucose tolerance during pregnancy from an Indian birth cohort (N = 486, age 13.5 years had detailed anthropometry and measurements of body fat (fat%, fasting plasma glucose, insulin and lipid concentrations, blood pressure and cognitive function. Insulin resistance (HOMA-IR was calculated. These outcomes were examined in relation to birth measurements and statistically independent measures (conditional SD scores representing linear growth, and fat and lean tissue gain during birth-1, 1-2, 2-5, 5-9.5 and 9.5-13.5 years in 414 of the children with measurements at all these ages.Birth length and linear growth at all ages were positively associated with current height. Fat gain, particularly during 5-9.5 years was positively associated with fat% at 13.5 years (0.44 SD per SD [99.9% confidence interval: 0.29,0.58]. Greater fat gain during mid-late childhood was associated with higher systolic blood pressure (5-9.5 years: 0.23 SD per SD [0.07,0.40] and HOMA-IR (5-9.5 years: 0.24 [0.08,0.40], 9.5-13.5 years: 0.22 [0.06,0.38]. Greater infant growth (up to age 2 years in linear, fat or lean components was unrelated to cardiometabolic risk factors or cognitive function.This study suggests that factors that increase linear, fat and lean growth in infancy have no adverse cardiometabolic effects in this population. Factors that increase fat gain in mid-late childhood may increase cardiometabolic risk, without any benefit to cognitive abilities.

  19. Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system

    Science.gov (United States)

    Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.

    2016-01-01

    It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).

  20. Hierarchical weeping willow nano-tree growth and effect of branching on dye-sensitized solar cell efficiency.

    Science.gov (United States)

    Herman, Indria; Yeo, Junyeob; Hong, Sukjoon; Lee, Daeho; Nam, Koo Hyun; Choi, Jun-ho; Hong, Won-hwa; Lee, Dongjin; Grigoropoulos, Costas P; Ko, Seung Hwan

    2012-05-17

    In this paper we have demonstrated the simple, low cost, low temperature, hydrothermal growth of weeping willow ZnO nano-trees with very long branches to realize high efficiency dye-sensitized solar cells (DSSCs). We also discuss the effects of branching on solar cell efficiency. By introducing branched growth on the backbone ZnO nanowires (NWs), the short circuit current density and the overall light conversion efficiency of the branched ZnO NW DSSCs increased to almost four times that for vertically grown ZnO NWs. The efficiency increase is attributed to the increase in surface area for higher dye loading and light harvesting and also to reduced charge recombination through direct conduction along the crystalline ZnO branches. As the length of the branches increased, the branches became flaccid and the increase in solar cell efficiency slowed down because the effective surface area increase was hindered by branch bundling during the drying process and subsequent decrease in the dye loading.

  1. The lesional skin of linear IgA bullous dermatosis expresses growth-regulated peptide (GRO)-alpha.

    Science.gov (United States)

    Tsunemi, Yuichiro; Ihn, Hironobu; Saeki, Hidehisa; Tamaki, Kunihiko

    2004-07-01

    The patient was a 62-year-old man with erythema with tense vesiculobullae and erosions on the bilateral elbows, right knee, and one buttock. A skin biopsy specimen revealed subepidermal blister formation with a predominant infiltration of neutrophils and papillary neutrophilic microabscesses. Direct immunofluorescence study showed linear deposition of IgA and weak deposition of IgG at the basement membrane zone of the lesional skin, and indirect immunofluorescence study showed linear deposition of IgA at the epidermal side of the 1M NaCl-separated normal skin. He was diagnosed with linear IgA bullous dermatosis. Immunohistochemical study revealed that the lesional and perilesional keratinocytes expressed growth-regulated peptide (GRO) -alpha, a potent chemoattractant for neutrophils. This suggests that GRO-alpha plays a role in the infiltration of neutrophils into the lesional skin and in bulla formation in linear IgA bullous dermatosis.

  2. Associations of Linear Growth and Relative Weight Gain in Early Life with Human Capital at 30 Years of Age.

    Science.gov (United States)

    Horta, Bernardo Lessa; Victora, Cesar G; de Mola, Christian Loret; Quevedo, Luciana; Pinheiro, Ricardo Tavares; Gigante, Denise P; Motta, Janaina Vieira Dos Santos; Barros, Fernando C

    2017-03-01

    To assess the associations of birthweight, nutritional status and growth in childhood with IQ, years of schooling, and monthly income at 30 years of age. In 1982, the 5 maternity hospitals in Pelotas, Brazil, were visited daily and 5914 live births were identified. At 30 years of age, 3701 subjects were interviewed. IQ, years of schooling, and income were measured. On average, their IQ was 98 points, they had 11.4 years of schooling, and the mean income was 1593 reais. After controlling for several confounders, birthweight and attained weight and length/height for age at 2 and 4 years of age were associated positively with IQ, years of years of schooling, and income, except for the association between length at 2 years of age and income. Conditional growth analyses were used to disentangle linear growth from relative weight gain. Conditional length at 2 years of age ≥1 SD score above the expected value, compared with ≥1 SD below the expected, was associated with an increase in IQ (4.28 points; 95% CI, 2.66-5.90), years of schooling (1.58 years; 95% CI, 1.08-2.08), and monthly income (303 Brazilian reais; 95% CI, 44-563). Relative weight gain, above what would be expected from linear growth, was not associated with the outcomes. In a middle-income setting, promotion of linear growth in the first 1000 days of life is likely to increase adult IQ, years of schooling, and income. Weight gain in excess of what is expected from linear growth does not seem to improve human capital. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Combination therapy with acipimox enhances the effect of growth hormone treatment on linear body growth in the normal and small-for-gestational-age rat.

    Science.gov (United States)

    Vickers, M H; Hofman, P L; Gluckman, P D; Lobie, P E; Cutfield, W S

    2006-12-01

    Growth hormone (GH) therapy is often associated with adverse side effects, including impaired insulin sensitivity. GH treatment of children with idiopathic short stature does not lead to an optimized final adult height. It has been demonstrated that FFA reduction induced by pharmacological antilipolysis can stimulate GH secretion per se in both normal subjects and those with GH deficiency. However, to date, no investigation has been undertaken to establish efficacy of combination treatment with GH and FFA regulators on linear body growth. Using a model of maternal undernutrition in the rat to induce growth-restricted offspring, we investigated the hypothesis that combination treatment with GH and FFA regulators can enhance linear body growth above that of GH alone. At postnatal day 28, male offspring of normally nourished mothers (controls) and offspring born with low birth weight [small for gestational age (SGA)] were treated with saline, GH, or GH (5 mg.kg(-1).day(-1)) in combination with acipimox (GH + acipimox, 20 mg.kg(-1).day(-1)) or fenofibrate (GH + fenofibrate, 30 mg.kg(-1).day(-1)) for 40 days. GH plus acipimox treatment significantly enhanced linear body growth in the control and SGA animals above that of GH, as quantified by tibial and total body length. Treatment with GH significantly increased fasting plasma insulin, insulin-to-glucose ratio, and plasma volumes in control and SGA animals but was not significantly different between saline and GH-plus-acipimox-treated animals. GH-induced lipolysis was blocked by GH plus acipimox treatment in both control and SGA animals, concomitant with a significant reduction in fasting plasma FFA and insulin concentrations. This is the first study to show that GH plus acipimox combination therapy, via pharmacological blocking of lipolysis during GH exposure, can significantly enhance the efficacy of GH in linear growth promotion and ameliorate unwanted metabolic side effects.

  4. Hierarchical matrices algorithms and analysis

    CERN Document Server

    Hackbusch, Wolfgang

    2015-01-01

    This self-contained monograph presents matrix algorithms and their analysis. The new technique enables not only the solution of linear systems but also the approximation of matrix functions, e.g., the matrix exponential. Other applications include the solution of matrix equations, e.g., the Lyapunov or Riccati equation. The required mathematical background can be found in the appendix. The numerical treatment of fully populated large-scale matrices is usually rather costly. However, the technique of hierarchical matrices makes it possible to store matrices and to perform matrix operations approximately with almost linear cost and a controllable degree of approximation error. For important classes of matrices, the computational cost increases only logarithmically with the approximation error. The operations provided include the matrix inversion and LU decomposition. Since large-scale linear algebra problems are standard in scientific computing, the subject of hierarchical matrices is of interest to scientists ...

  5. Stunted at 10 Years. Linear Growth Trajectories and Stunting from Birth to Pre-Adolescence in a Rural Bangladeshi Cohort.

    Directory of Open Access Journals (Sweden)

    Pernilla Svefors

    Full Text Available Few studies in low-income settings analyse linear growth trajectories from foetal life to pre-adolescence. The aim of this study is to describe linear growth and stunting from birth to 10 years in rural Bangladesh and to analyse whether maternal and environmental determinants at conception are associated with linear growth throughout childhood and stunting at 10 years.Pregnant women participating in the MINIMat trial were identified in early pregnancy and a birth cohort (n = 1054 was followed with 19 growth measurements from birth to 10 years. Analyses of baseline predictors and mean height-for-age Z-scores (HAZ over time were modelled using GLMM. Logistic regression analysis was used to investigate the associations between baseline predictors and stunting (HAZ<-2 at 10 years. HAZ decreased to 2 years, followed by an increase up to 10 years, while the average height-for-age difference in cm (HAD to the WHO reference median continued to increase up to 10 years. Prevalence of stunting was highest at 2 years (50% decreasing to 29% at 10 years. Maternal height, maternal educational level and season of conception were all independent predictors of HAZ from birth to pre-adolescence (p<0.001 and stunting at 10 years. The highest probability to be stunted at 10 years was for children born by short mothers (<147.5 cm (ORadj 2.93, 95% CI: 2.06-4.20, mothers with no education (ORadj 1.74, 95% CI 1.17-2.81 or those conceived in the pre-monsoon season (ORadj 1.94, 95% CI 1.37-2.77.Height growth trajectories and prevalence of stunting in pre-adolescence showed strong intergenerational associations, social differentials, and environmental influence from foetal life. Targeting women before and during pregnancy is needed for the prevention of impaired child growth.

  6. Econometric Modelling of the Variations of Norway’s Export Trade across Continents and over Time: The Two-Stage Non-Full Rank Hierarchical Linear Econometric Model Approach

    Directory of Open Access Journals (Sweden)

    Yohannes Yebabe Tesfay

    2015-01-01

    Full Text Available This paper applies the two-stage hierarchical non-full rank linear econometric model to make a deep analysis based on revenue generated from key Norwegian export items over the world’s continents. The model’s ability to analyse the variation of Norway’s export trade gives us the following interesting details: (1 for each continent intra- and intervariation of export items, (2 access to deep knowledge about the characteristics of the Norway’s export items revenue, (3 quantifying the economic importance and sustainability of export items within continents; and finally (4 comparing a given export item economic importance across continents. The results suggest the following important policy implications for Norway. First, Europe is the most important trade partner for Norway. In fact, 81.5% of Norwegian export items are transported to Europe. Second, there is a structural shift in Norwegian exports from North and Central America to Asia and Oceania. Third, the new importance of Asia and Oceania is also emphasized by the 85% increase in export revenues over the period 1988–2012. The trade pattern has changed and trade policy must change accordingly. The analysis has shown that in 2012 there are two important export continents for Norway: Europe and Asia and Oceania.

  7. Taurine, a major amino acid of oyster, enhances linear bone growth in a mouse model of protein malnutrition.

    Science.gov (United States)

    Moon, Phil-Dong; Kim, Min-Ho; Lim, Hun-Sun; Oh, Hyun-A; Nam, Sun-Young; Han, Na-Ra; Kim, Myong-Jo; Jeong, Hyun-Ja; Kim, Hyung-Min

    2015-05-06

    Oysters (Oys) contain various beneficial components, such as, antioxidants and amino acids. However, the effects of Oys or taurine (Tau), a major amino acid in Oys on bone growth have not been determined. In the present study, we evaluated the effects of Oys or Tau on linear bone growth in a mouse model of protein malnutrition. To make the protein malnutrition in a mouse, we used a low protein diet. Growth plate thickness was increased by Oys or Tau. Bone volume/tissue volume, trabecular thickness, trabecular number, connection density, and total porosity were also improved by Oys or Tau. Oys or Tau increased insulin-like growth factor-1 (IGF-1) levels in serum, liver, and tibia-growth plate. Phosphorylations of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5) were increased by Oys and by Tau. These findings show that Oys or Tau may increase growth plate thickness by elevating IGF-1 levels and by promoting the phosphorylations of JAK2-STAT5, and suggest that Oys or Tau are growth-promoting substances of potential use in the food and pharmaceutical industries. © 2015 International Union of Biochemistry and Molecular Biology.

  8. Inflammation and linear bone growth: the inhibitory role of SOCS2 on GH/IGF-1 signaling.

    Science.gov (United States)

    Farquharson, Colin; Ahmed, S Faisal

    2013-04-01

    Linear bone growth is widely recognized to be adversely affected in children with chronic kidney disease (CKD) and other chronic inflammatory disorders. The growth hormone (GH)/insulin-like growth factor-1 (IGF-1) pathway is anabolic to the skeleton and inflammatory cytokines compromise bone growth through a number of different mechanisms, which include interference with the systemic as well as the tissue-level GH/IGF-1 axis. Despite attempts to promote growth and control disease, there are an increasing number of reports of the persistence of poor growth in a substantial proportion of patients receiving rhGH and/or drugs that block cytokine action. Thus, there is an urgent need to consider better and alternative forms of therapy that are directed specifically at the mechanism of the insult which leads to abnormal bone health. Suppressor of cytokine signaling 2 (SOCS2) expression is increased in inflammatory conditions including CKD, and is a recognized inhibitor of GH signaling. Therefore, in this review, we will focus on the premise that SOCS2 signaling represents a critical pathway in growth plate chondrocytes through which pro-inflammatory cytokines alter both GH/IGF-1 signaling and cellular function.

  9. Stability of bubbles in a linear elastic medium: Implications for bubble growth in marine sediments

    Science.gov (United States)

    Algar, C. K.; Boudreau, B. P.

    2010-09-01

    Methane bubbles in muddy fine-grained sediments grow initially through a process of elastic expansion, punctuated by discrete fracture events (LEFM-growth). The ability of the surrounding sediments to support a stress and actively resist expansion can, under conditions of low gas production or high sediment toughness, result in the cessation of growth and the presence of stable bubbles. Thus, it is possible for a bubble to stop growing despite the presence of a source in the sediments that continues to produce gas. This contrasts with growth of bubbles in a fluid medium, which cannot support a stress and so will continue to grow as long as a surrounding source provides gas. This "no-growth" condition is the result of the coupling between gas supply (methane production or supersaturation) and the sediment mechanics. Here we quantify this condition and present a criterion for the switch between no-growth and the LEFM growth regimes. We apply this theory to the sediments of Eckernförde Bay, in the Kiel Bight, Germany, and despite the absence of measurements for the key sediment mechanical properties, we can provide a qualitative explanation for the sizes and shapes of the observed bubble population with depth in the sediment. We also show how the release of hydrostatic pressure can stimulate growth, by pushing otherwise stable bubbles into the LEFM growth regime. This could provide a mechanism for the release of bubbles during periods of low water, such as during low tide or wave events.

  10. The Oportunidades program increases the linear growth of children enrolled at young ages in urban Mexico.

    Science.gov (United States)

    Leroy, Jef L; García-Guerra, Armando; García, Raquel; Dominguez, Clara; Rivera, Juan; Neufeld, Lynnette M

    2008-04-01

    The goal of this study was to evaluate the impact of Mexico's conditional cash transfer program, Oportunidades, on the growth of children Oportunidades, with its strong nutrition component, is an effective tool to improve the growth of infants in poor urban households.

  11. Linear spectral unmixing to monitor crop growth in typical organic and inorganic amended arid soil

    Science.gov (United States)

    El Battay, A.; Mahmoudi, H.

    2016-06-01

    The soils of the GCC countries are dominantly sandy which is typical of arid regions such as the Arabian Peninsula. Such soils are low in nutrients and have a poor water holding capacity associated with a high infiltration rate. Soil amendments may rehabilitate these soils by restoring essential soil properties and hence enable site revegetation and revitalization for crop production, especially in a region where food security is a priority. In this study, two inorganic amendments; AustraHort and Zeoplant pellet, and one organic locally produced compost were tested as soil amendments at the experimental field of the International Center for Biosaline Agriculture in Dubai, UAE. The main objective is to assess the remote sensing ability to monitor crop growth, for instance Okra (Abelmoschus esculentus), having these amendments, as background with the soil. Three biomass spectral vegetation indices were used namely; NDVI, TDVI and SAVI. Pure spectral signatures of the soil and the three amendments were collected, using a field spectroradiometer, in addition to the spectral signatures of Okra in two growing stages (vegetative and flowering) in the field with a mixed F.O.V of the plant and amended soil during March and May 2015. The spectral signatures were all collected using the FieldSpec® HandHeld 2 (HH2) in the spectral range 325 nm - 1075 nm over 12 plots. A set of 4 plots were assigned for each of the three amendments as follow: three replicates of a 1.5 by 1.5 meter plot with 3kg/m2 of each amendment and 54 plants, one plot as control and all plots were given irrigation treatments at 100% based on ETc. Spectra collected over the plots were inversed in the range of 400-900 nm via a Linear Mixture Model using pure soil and amendments spectral signatures as reference. Field pictures were used to determine the vegetation fraction (in term of area of the F.O.V). Hence, the Okra spectral signatures were isolated for all plots with the three types of amendments. The

  12. Effect of therapy with a new glucocorticoid, deflazacort, on linear growth and growth hormone secretion after renal transplantation.

    Science.gov (United States)

    Ferraris, J R; Fainstein Day, P; Gutman, R; Granillo, E; Ramirez, J; Ruiz, S; Pasqualini, T

    1992-11-01

    Deflazacort is an oxazoline compound derived from prednisolone with similar antiinflammatory effects but fewer side effects. We studied changes in kidney function, growth velocity, weight/height ratio, and growth hormone secretion before and a year after substitution of deflazacort for methylprednisone in nine patients aged 9 to 15 years, 4 years after renal transplantation; all were in Tanner pubertal stage 1. Methylprednisone (mean +/- SEM: 0.2 +/- 0.02 mg/kg per day) was replaced by deflazacort (0.3 +/- 0.03 mg/kg per day) for a mean period of 15 months. Serum creatinine and calculated creatinine clearance did not change significantly during deflazacort treatment. Growth velocity increased from 1.5 +/- 0.3 to 3.2 +/- 0.5 cm/yr (p < 0.005) in the nine patients. Weight/height ratio decreased from 28.4% +/- 8.5% to 16% +/- 6.7% (p < 0.005). Cushingoid appearance decreased in all patients. Mean spontaneous growth hormone secretion increased from 2.5 +/- 0.4 to 4.4 +/- 1.2 ng/ml (p < 0.05). Our findings indicate that immunosuppressive treatment with deflazacort is as effective as methylprednisone and is associated with fewer side effects.

  13. Non-linear growth: The road ahead for Indian IT outsourcing companies

    Directory of Open Access Journals (Sweden)

    Y.L.R. Moorthi

    2011-06-01

    Full Text Available Indian IT outsourcing companies (major among them being the SWITCH companies -- Satyam, Wipro, Infosys, TCS, Cognizant and HCL grew rapidly for more than a decade on low cost business process and IT outsourcing. With the bigger companies already reaching a high of 100,000 employees, they are now turning their attention to non-linear revenue (i.e. revenue less dependent on numbers or greater revenue earned per employee. For this they need to pursue ‘disruptive’ strategies which are distinctly different from the ‘incremental’ initiatives they adopted in the past to maintain linear revenue. This paper first outlines the disruptive and the incremental initiatives of the SWITCH companies and the road ahead for them. This is followed by an interview with S Gopalakrishnan, CEO and MD, Infosys Technologies who discusses the non-linear initiatives of the company and the challenges it faces in the field.

  14. Distribution of linear growth rates in different directions in root apical meristems

    Directory of Open Access Journals (Sweden)

    Jerzy Nakielski

    2014-01-01

    Full Text Available Growth of apical meristems in plants may be well described by the growth tensor method. Hejnowicz (Envir. Exp. Bot. 1989, 29 determined growth tensors for roots: one with a minimum and the other with a maximum of the relative elemental growth rate in volume and used them for the description of two types of apices: one with an apical cell and merophytes (I, and the other with files of cells converging towards a quiescent centre, CQ (II. In the present paper the same cases are considered from the point of view of a spatial and directional variation of the relative elemental rate of growth in length, RERG1. Maps of the RERG1 in two planes: axial and tangential, the latter determined by periclinal-longitudinal (PL and periclinal-tangential (PT principal growth directions, are shown. In an apical part of apex i where there is maximum volumetric growth, there also occurs a maximum of RERG1 for all directions. In regions other than this RERG1 decreases although RERG1 in the PL direction predominates everywhere. In apex II RERG1 for all directions has a minimum in CQ and becomes increasingly larger with increasing distance from it - the maximum is in the PL direction in the cylindrical part of the apex. In peripheral parts of both apices, in the place of the root/cap junction, RERG, in the anticlinal direction is significantly small.

  15. Selecting a linear mixed model for longitudinal data: repeated measures analysis of variance, covariance pattern model, and growth curve approaches.

    Science.gov (United States)

    Liu, Siwei; Rovine, Michael J; Molenaar, Peter C M

    2012-03-01

    With increasing popularity, growth curve modeling is more and more often considered as the 1st choice for analyzing longitudinal data. Although the growth curve approach is often a good choice, other modeling strategies may more directly answer questions of interest. It is common to see researchers fit growth curve models without considering alterative modeling strategies. In this article we compare 3 approaches for analyzing longitudinal data: repeated measures analysis of variance, covariance pattern models, and growth curve models. As all are members of the general linear mixed model family, they represent somewhat different assumptions about the way individuals change. These assumptions result in different patterns of covariation among the residuals around the fixed effects. In this article, we first indicate the kinds of data that are appropriately modeled by each and use real data examples to demonstrate possible problems associated with the blanket selection of the growth curve model. We then present a simulation that indicates the utility of Akaike information criterion and Bayesian information criterion in the selection of a proper residual covariance structure. The results cast doubt on the popular practice of automatically using growth curve modeling for longitudinal data without comparing the fit of different models. Finally, we provide some practical advice for assessing mean changes in the presence of correlated data.

  16. Growth of linear Ni-filled carbon nanotubes by local arc discharge in liquid ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, Takuya [Department of Electric Engineering, Graduated School of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan); Kurumi, Satoshi [Department of Electric Engineering, College of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan); Suzuki, Kaoru, E-mail: kaoru@ele.cst.nihon-u.ac.jp [Department of Electric Engineering, College of Science and Technology, Nihon University, 1-8-14 Surugadai Kanda, Chiyoda, Tokyo 101-8308 (Japan)

    2014-02-15

    The cylindrical geometry of carbon nanotubes (CNTs) allows them to be filled with metal catalysts; the resulting metal-filled CNTs possess different properties depending on the filler metal. Here we report the synthesis of Ni-filled CNTs in which Ni is situated linearly and homogeneously by local arc discharge in liquid ethanol. The structural characteristics of synthesized Ni-filled CNTs were determined by transmission electron microscopy (TEM), and the relationship between pyrolysis conditions and the length and diameter of Ni-filled CNTs was examined. The encapsulated Ni was identified by a TEM-equipped energy-dispersive X-ray spectroscope and found to have a single-crystal fcc structure by nano-beam diffraction. The features of linear Ni-filled CNT are expected to be applicable to probes for magnetic force microscopy.

  17. How maternal malnutrition affects linear growth and development in the offspring.

    Science.gov (United States)

    Papathakis, Peggy C; Singh, Lauren N; Manary, Mark J

    2016-11-05

    Maternal malnutrition is common in the developing world and has detrimental effects on both the mother and infant. Pre-pregnancy nutritional status and weight gain during pregnancy are positively related to fetal growth and development. Internationally, there is no agreement on the method of diagnosis or treatment of moderate or severe malnutrition during pregnancy. Establishing clear guidelines for diagnosis and treatment will be essential in elevating the problem. Possible anthropometric measurements used to detect and monitor maternal malnutrition include pre-pregnancy BMI, weight gain, and mid upper arm circumference. Food supplements have the potential to increase gestational weight gain and energy intake which are positively associated with fetal growth and development. Overall more studies are needed to conclude the impact of food/nutrient supplements on infant growth in undernourished pregnant women in developing countries. Currently, a study underway may provide much needed documentation of the benefits of treating malnutrition in pregnancy.

  18. Stochastic differential equation model for linear growth birth and death processes with immigration and emigration

    Science.gov (United States)

    Granita, Bahar, A.

    2015-03-01

    This paper discusses on linear birth and death with immigration and emigration (BIDE) process to stochastic differential equation (SDE) model. Forward Kolmogorov equation in continuous time Markov chain (CTMC) with a central-difference approximation was used to find Fokker-Planckequation corresponding to a diffusion process having the stochastic differential equation of BIDE process. The exact solution, mean and variance function of BIDE process was found.

  19. Stochastic differential equation model for linear growth birth and death processes with immigration and emigration

    Energy Technology Data Exchange (ETDEWEB)

    Granita, E-mail: granitafc@gmail.com [Dept. Mathematical Education, State Islamic University of Sultan Syarif Kasim Riau, 28293 Indonesia and Dept. of Mathematical Science, Universiti Teknologi Malaysia, 81310,Johor (Malaysia); Bahar, A. [Dept. of Mathematical Science, Universiti Teknologi Malaysia, 81310,Johor Malaysia and UTM Center for Industrial and Applied Mathematics (UTM-CIAM) (Malaysia)

    2015-03-09

    This paper discusses on linear birth and death with immigration and emigration (BIDE) process to stochastic differential equation (SDE) model. Forward Kolmogorov equation in continuous time Markov chain (CTMC) with a central-difference approximation was used to find Fokker-Planckequation corresponding to a diffusion process having the stochastic differential equation of BIDE process. The exact solution, mean and variance function of BIDE process was found.

  20. Normal Subgroup Growth of Linear Groups: the (G2; F4;E8)-Theorem

    CERN Document Server

    Larsen, Michael

    2011-01-01

    Let G be a finitely generated group and M_n(G) the number of its normal subgroup subgroups of index at most n. For linear groups G we show that M_n(G) can grow polynomially in n only if the semisimple part of the Zariski closure of G has simple components only of type G2, F4 or E8 (and in this case indeed this can happened!)

  1. Growth Trajectories of Mathematics Achievement: Longitudinal Tracking of Student Academic Progress

    Science.gov (United States)

    Mok, Magdalena M. C.; McInerney, Dennis M.; Zhu, Jinxin; Or, Anthony

    2015-01-01

    Background: A number of methods to investigate growth have been reported in the literature, including hierarchical linear modelling (HLM), latent growth modelling (LGM), and multidimensional scaling applied to longitudinal profile analysis (LPAMS). Aims: This study aimed at modelling the mathematics growth of students over a span of 6 years from…

  2. How Much Growth Can We Expect? A Conditional Analysis of R-CBM Growth Rates by Level of Performance

    Science.gov (United States)

    Silberglitt, Benjamin; Hintze, John M.

    2007-01-01

    This study examined the reading growth rates of 7,544 students in Grades 2-6, measured over 1 year using Reading-Curriculum-Based Measurement (R-CBM) benchmark assessments administered in the fall, winter, and spring. The authors used hierarchical linear modeling to establish and compare student rates of growth within each grade level based on…

  3. How maternal malnutrition affects linear growth and development in the offspring

    Science.gov (United States)

    Maternal malnutrition is common in the developing world and has detrimental effects on both the mother and infant. Pre-pregnancy nutritional status and weight gain during pregnancy are positively related to fetal growth and development. Internationally, there is no agreement on the method of diagnos...

  4. Existence of Nontrivial Weak Solutions to Quasi-Linear Elliptic Equations with Exponential Growth

    Institute of Scientific and Technical Information of China (English)

    WANG Chong

    2013-01-01

    In this paper,we study the existence of nontrivial weak solutions to the following quasi-linear elliptic equations -△nu+V(x)|u|n-2u-f(x,u)/|x|β,x∈Rn (n≥2),where-△nu=-div(|▽u|n-2▽7u),0≤β < n,V∶ Rn → R is a continuous function,f (x,u)is continuous in Rn × R and behaves like eαun/n-1 as u → +∞.

  5. Essential growth rate for bounded linear perturbation of non-densely defined Cauchy problems

    Science.gov (United States)

    Ducrot, A.; Liu, Z.; Magal, P.

    2008-05-01

    This paper is devoted to the study of the essential growth rate of some class of semigroup generated by bounded perturbation of some non-densely defined problem. We extend some previous results due to Thieme [H.R. Thieme, Quasi-compact semigroups via bounded perturbation, in: Advances in Mathematical Population Dynamics--Molecules, Cells and Man, Houston, TX, 1995, in: Ser. Math. Biol. Med., vol. 6, World Sci. Publishing, River Edge, NJ, 1997, pp. 691-711] to a class of non-densely defined Cauchy problems in Lp. In particular in the context the integrated semigroup is not operator norm locally Lipschitz continuous. We overcome the lack of Lipschitz continuity of the integrated semigroup by deriving some weaker properties that are sufficient to give information on the essential growth rate.

  6. Emittance Growth Due to Multiple Coulomb Scattering in a Linear Collider Based on Plasma Wakefield Acceleration

    CERN Document Server

    Mete, Oznur; Xia, Guoxing; Labiche, Marc; Karamyshev, Oleg; Wei, Yelong; Welsch, Carsten; Wing, Matthew

    2014-01-01

    Alternative acceleration technologies are currently under development for cost-effective, robust, compact and efficient solutions. One such technology is plasma wakefield acceleration, driven by either a charged particle or laser beam. However, the potential issues must be studied in detail. In this paper, the emittance growth of the witness beam through elastic scattering from gaseous media is derived. The model is compared with the numerical studies.

  7. Impact of pediatric inflammatory bowel disease on linear growth: Data from a national cohort study in Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Mohammad I El Mouzan

    2016-01-01

    Full Text Available Background/Aim: Linear growth impairment (LGI is one of the most important features peculiar to children with inflammatory bowel disease (IBD. The aim of this report is to define the impact of IBD on the linear growth of children in the Kingdom of Saudi Arabia (KSA. Setting and Design: Multicenter retrospective study. Patients and Methods: Data from a cohort of newly- diagnosed children with IBD from 2003 to 2012 were analyzed retrospectively. The diagnosis of IBD was confirmed in accordance with the published criteria. Length/height for age was measured at diagnosis. The World Health Organization (WHO reference was used and LGI was defined by length/height for age <-2 standard deviation. Chi-square test was used to test the significance of estimates and a P < 0.05 was considered significant. Results: There were 374 children from 0.33 to 16 years of age, including 119 ulcerative colitis (UC (32%, and 255 Crohn's disease (CD (68% patients. The prevalence of LGI was 26%, 28%, and 21% in IBD, CD, and UC, respectively. In children below 10 years, LGI was significantly more common in CD (P = 0.010, while in UC children, it was more common in older children (P = 0.011. Conclusion: This study demonstrates a prevalence of LGI consistent with that reported in the literature, but higher in CD children with early onset (<10 years and in older children with UC, underscoring the importance of monitoring growth in children with IBD in the Saudi population. Prospective studies are needed to define the impact of IBD on growth velocity, puberty, and final adult stature.

  8. Stunting at birth: recognition of early-life linear growth failure in the western highlands of Guatemala.

    Science.gov (United States)

    Solomons, Noel W; Vossenaar, Marieke; Chomat, Anne-Marie; Doak, Colleen M; Koski, Kristine G; Scott, Marilyn E

    2015-07-01

    Measurements of length at birth, or in the neonatal period, are challenging to obtain and often discounted for lack of validity. Hence, classical 'under-5' stunting rates have been derived from surveys on children from 6 to 59 months of age. Guatemala has a high prevalence of stunting (49.8%), but the age of onset of growth failure is not clearly defined. The objective of the study was to assess length-for-age within the first 1.5 months of life among Guatemalan infants. As part of a cross-sectional observational study, supine length was measured in young infants. Mothers' height was measured. Length-for-age Z-scores (HAZ) were generated and stunting was defined as HAZ <-2 using WHO growth standards. Eight rural, indigenous Mam-Mayan villages (n 200, 100% of Mayan indigenous origin) and an urban clinic of Quetzaltenango (n 106, 27% of Mayan indigenous origin), Guatemala. Three hundred and six newborns with a median age of 19 d. The median rural HAZ was -1.56 and prevalence of stunting was 38%; the respective urban values were -1.41 and 25%. Linear regression revealed no relationship between infant age and HAZ (r = 0.101, r(2) = 0.010, P = 0.077). Maternal height explained 3% of the variability in HAZ (r = 0.171, r(2) = 0.029, P = 0.003). Stunting must be carried over from in utero growth retardation in short-stature Guatemalan mothers. As linear growth failure in this setting begins in utero, its prevention must be linked to maternal care strategies during gestation, or even before. A focus on maternal nutrition and health in an intergenerational dimension is needed to reduce its prevalence.

  9. Hierarchical Multiagent Reinforcement Learning

    Science.gov (United States)

    2004-01-25

    In this paper, we investigate the use of hierarchical reinforcement learning (HRL) to speed up the acquisition of cooperative multiagent tasks. We...introduce a hierarchical multiagent reinforcement learning (RL) framework and propose a hierarchical multiagent RL algorithm called Cooperative HRL. In

  10. Hierarchical growth of TiO2 nanosheets on anodic ZnO nanowires for high efficiency dye-sensitized solar cells

    Science.gov (United States)

    Miles, David O.; Lee, Chang Soo; Cameron, Petra J.; Mattia, Davide; Kim, Jong Hak

    2016-09-01

    We present a novel route to hierarchical core-shell structures consisting of an anodic ZnO nanowire core surrounded by a shell of TiO2 nanosheets (ZNW@TNS). This material combines the beneficial properties of enhanced electron transport, provided by the nanowire core, with the high surface area and chemical stability of the TiO2 shell. Quasi-solid-state dye-sensitized solar cells (qssDSSCs) are prepared using different quantities of either the bare ZnO nanowires or the hierarchical nanowire structures and the effect on cell performance is examined. It is found that whilst the addition of the bare ZnO nanowires results in a decrease in cell performance, significant improvements can be achieved with the addition of small quantities of the hierarchical structures. Power conversion efficiencies of up to 7.5% are achieved under 1 Sun, AM 1.5 simulated sunlight, with a ∼30% increase compared to non-hierarchical mesoporous TiO2 films. A solid-state DSSC (ssDSSC) with a single component solid polymer also exhibits excellent efficiency of 7.2%. The improvement in cell performance is related to the improved light scattering, surface area and electron transport properties via the use of reflectance spectroscopy, BET surface area measurements and electrochemical impedance spectroscopy.

  11. Effects of linear alkylbenzene sulfonate on the growth and toxin production of Microcystis aeruginosa isolated from Lake Dianchi.

    Science.gov (United States)

    Wang, Zhi; Zhang, Junqian; Song, Lirong; Li, Enhua; Wang, Xuelei; Xiao, Bangding

    2015-04-01

    The exogenous organic pollutant linear alkylbenzene sulfonate (LAS) pollution and Microcystis bloom are two common phenomena in eutrophic lakes, but the effects of LAS alone on Microcystis remain unclear. In the present study, we investigated the effects of LAS on the growth, photochemical efficiency, and microcystin production of Microcystis aeruginosa in the laboratory. Results showed that low LAS (≤10 mg/L) concentrations improved the growth of M. aeruginosa (12 days of exposure). High LAS (20 mg/L) concentrations inhibited the growth of M. aeruginosa on the first 8 days of exposure; afterward, growth progressed. After 12 days of exposure, the concentrations of chlorophyll a in algal cells were not significantly affected by any of LAS concentrations (0.05 to 20 mg/L) in the present study; by contrast, carotenoid and protein concentrations were significantly inhibited when LAS concentrations reached as high as 20 mg/L. After 6 and 12 days of exposure, low LAS (≤10 mg/L) concentrations enhanced the maximal photochemical efficiency (Fv/Fm) and the maximal electron transport rate (ETRmax) of M. aeruginosa. Furthermore, LAS increased the microcystin production of M. aeruginosa. Extracellular and intracellular microcystin contents were significantly increased after M. aeruginosa was exposed to high LAS concentrations. Our results indicated that LAS in eutrophic lakes may increase the risk of Microcystis bloom and microcystin production.

  12. Memory Stacking in Hierarchical Networks.

    Science.gov (United States)

    Westö, Johan; May, Patrick J C; Tiitinen, Hannu

    2016-02-01

    Robust representations of sounds with a complex spectrotemporal structure are thought to emerge in hierarchically organized auditory cortex, but the computational advantage of this hierarchy remains unknown. Here, we used computational models to study how such hierarchical structures affect temporal binding in neural networks. We equipped individual units in different types of feedforward networks with local memory mechanisms storing recent inputs and observed how this affected the ability of the networks to process stimuli context dependently. Our findings illustrate that these local memories stack up in hierarchical structures and hence allow network units to exhibit selectivity to spectral sequences longer than the time spans of the local memories. We also illustrate that short-term synaptic plasticity is a potential local memory mechanism within the auditory cortex, and we show that it can bring robustness to context dependence against variation in the temporal rate of stimuli, while introducing nonlinearities to response profiles that are not well captured by standard linear spectrotemporal receptive field models. The results therefore indicate that short-term synaptic plasticity might provide hierarchically structured auditory cortex with computational capabilities important for robust representations of spectrotemporal patterns.

  13. Using Personality Traits to Construct Linear Growth Models of Mental Health in Family Members of Individuals With Severe Brain Injury

    DEFF Research Database (Denmark)

    Trujillo, Michael; Perrin, Paul B; Doser, Karoline

    2016-01-01

    Objective: No studies have examined the impact of personality traits on mental health among caregivers of individuals with severe brain injury. Therefore, the purpose of the current study was to construct linear growth models to examine whether the personality traits of family members of individu......Objective: No studies have examined the impact of personality traits on mental health among caregivers of individuals with severe brain injury. Therefore, the purpose of the current study was to construct linear growth models to examine whether the personality traits of family members...... of individuals with severe brain injury could predict the trajectories of their own mental health-related quality of life (HRQoL), anxiety, and depression beginning in a neurointensive care unit through 1 year after injury. Method: Danish family members of individuals with severe brain injury (n = 52) completed...... the Short Form-36 assessing mental HRQoL (vitality, social functioning, role limitations-emotional, mental health), anxiety, and depression across 5 time points during the 1st year after injury. The measure of personality was administered 3 months after the patients' discharge. Results: All mental HRQo...

  14. Linear Growth Arrest Without Weight Gain Due to Overuse of Topical Clobetasol

    Directory of Open Access Journals (Sweden)

    Zahra Razavi

    2014-11-01

    Full Text Available Prolonged potent topical glucocorticoid therapy in infants can cause iatrogenic Cushing’s syndrome. This case highlights the rarity of poor weight gain in iatrogenic Cushing’s syndrome. A 17-month-old boy was referred to outpatients pediatric endocrine clinic for evaluation of growth failure. On presentation his weight was 9.7kg (5th percentile and height was 72cm (-3.6 SD below mean for age and sex. Systemic examination revealed grossly moon-like face, hypertrichosis and thin skin in the genital area. His mother reported using local clobetasol for the previous seven months for his diaper dermatitis. Baseline plasma cortisol was low (0.3ng/ml, normal range: 60 to 280ng/ml. During standard dose of synthetic adrenocorticotropic hormone test, the peak cortisol level was 0.4ng/ml (N>180ng/ml and was consistent with hypothalamic–pituitary–adrenal axis suppression. The patient’s clinical presentation and laboratory investigations confirmed the diagnosis of secondary adrenal insufficiency and iatrogenic Cushing’s syndrome. He was treated successfully by discontinuing use of clobetasol. His appearance and growth returned to normal within two months. Morning cortisol was 101.2ng/ml after stopping the oral physiologic dose of hydrocortisone. Our case differed from other reports of iatrogenic Cushing’s syndrome by presenting in poor weight gain rather than obesity.

  15. Zinc-iron, but not zinc-alone supplementation, increased linear growth of stunted infants with low haemoglobin.

    Science.gov (United States)

    Fahmida, Umi; Rumawas, Johanna S P; Utomo, Budi; Patmonodewo, Soemiarti; Schultink, Werner

    2007-01-01

    Zinc supplementation has been shown to benefit linear growth. However the effect may depend on whether zinc is the most limiting nutrient. This study aims to investigate the effect of supplementation with zinc-given alone or with iron and vitamin-A in improving infantsf micronutrient status and linear growth. The study was a double-blind-community-intervention study involving 800 infants aged 3-6 months in rural East Lombok, West Nusa Tenggara. Syrup consisting of zinc-alone, Zn (10 mg/d), zinc+iron, Zn+Fe (10 mg/d of each), zinc+iron+vitamin-A, Zn+Fe+vit.A (10 mg/d of each zinc and iron plus 1,000 IU vitamin-A), or placebo were given daily for six months. Outcomes measured were length, weight, and micronutrient status (haemoglobin, se-rum zinc, ferritin and retinol). Zn+Fe and Zn+Fe+vit.A supplementations benefit zinc and iron status of the sub-jects, while Zn-alone supplementation disadvantaged haemoglobin and iron status. The highest increment in vi-tamin A and haemoglobin status was shown in Zn+Fe+vit.A group. An effect on linear growth was observed among initially-stunted subjects in Zn+Fe and Zn+Fe+vit.A groups who grew 1.1-1.5 cm longer than placebo. On the other hand, in the Zn-alone group, mean height-for-age Z-score decreased to a greater extent than placebo. The between-group difference in HAZ among initially-stunted subjects was significant after four months sup-plementation. While the difference was not significant in follow-up after 6 months, the pattern remained the same where means height-for-age Z-score in Zn+Fe+vit.A and Zn+Fe groups were higher than placebo and Zn-alone groups. Given the low haemoglobin/iron status of the subjects, zinc supplementation would have positive effect on growth if the low haemoglobin/iron status is also addressed and corrected.

  16. Hierarchical Clustering and Active Galaxies

    CERN Document Server

    Hatziminaoglou, E; Manrique, A

    2000-01-01

    The growth of Super Massive Black Holes and the parallel development of activity in galactic nuclei are implemented in an analytic code of hierarchical clustering. The evolution of the luminosity function of quasars and AGN will be computed with special attention paid to the connection between quasars and Seyfert galaxies. One of the major interests of the model is the parallel study of quasar formation and evolution and the History of Star Formation.

  17. Hierarchical Network Design

    DEFF Research Database (Denmark)

    Thomadsen, Tommy

    2005-01-01

    Communication networks are immensely important today, since both companies and individuals use numerous services that rely on them. This thesis considers the design of hierarchical (communication) networks. Hierarchical networks consist of layers of networks and are well-suited for coping...... the clusters. The design of hierarchical networks involves clustering of nodes, hub selection, and network design, i.e. selection of links and routing of ows. Hierarchical networks have been in use for decades, but integrated design of these networks has only been considered for very special types of networks....... The thesis investigates models for hierarchical network design and methods used to design such networks. In addition, ring network design is considered, since ring networks commonly appear in the design of hierarchical networks. The thesis introduces hierarchical networks, including a classification scheme...

  18. 基于分层线性模型的流动人口社会融合影响因素研究%A Research on the Factors Affecting Social Integration of Floating Population Based on Hierarchical Linear Model

    Institute of Scientific and Technical Information of China (English)

    薛艳

    2016-01-01

    根据2012年全国流动人口动态监测结果和反映31个省市基本公共服务均等化的指标数据,建立分层线性模型从流动人口个体和省级层面考察影响流动人口社会融合的影响因素和作用程度的大小。研究发现,流动人口的社会融合不仅与个人因素有关,而且还受地区基本公共服务差异化的影响。个体层面从户口性质、就业状况、医疗保险、自我融入意愿、本地人接受程度、收入情况与住房条件解释流动人口社会融合差异的63�12%;省级层面从基础教育、医疗卫生、公共就业及基本社会保障解释流动人口社会融合的差异为36�83%。最后从政府、公民社会参与角度出发,提出促进流动人口社会融合的措施和建议。%Based on the dynamic monitoring of floating population in 2012 and the index data of 31 provinces and cities, this paper investigated the factors and their effect all the social integration of floating population using hierarchical linear model. It is found that the social integration of the floating population is not only related to individual factors, but also to the influence of regional basic public services. At individual level, a series of factors like nature of hukou, employment status, health insurance, self integration, local acceptance, income and housing conditions, are analyzed to explain the differences of 63�12% in social integration of migrant population; at the provincial level, factors like basic education, health care, public employment and basic social barriers are considered to explain the 36�83% of difference in social integration of the floating population. Finally, from the perspective of government and civil society participation, the measures and suggestions of promoting the social integration of floating population are proposed.

  19. 班级背景对中学生网络成瘾影响的多层线性分析%Hierarchical linear analysis of the impact of class context on Internet addiction among middle school students

    Institute of Scientific and Technical Information of China (English)

    吴贤华; 蒙衡; 吴汉荣

    2012-01-01

    目的 探讨班级背景对中学生网络成瘾的影响,为寻找班级背景变量及为干预中学生网络成瘾提供参考.方法 采用网络使用评价量表、长处与困难量表、青少年生活质量量表,对整群抽取的武汉与麻城两市2898名学生进行问卷调查,采用多层线性模型对网络成瘾影响因素进行分析.结果 性别、多动注意力缺陷、同伴问题与青少年生活质量总分在学生层上对网络成瘾有影响;情绪障碍、品行障碍在学生层与班级层对网络成瘾影响存在跨级交互作用;其中青少年生活质量和同伴问题对网络成瘾起负向预测作用;班级背景对网络成瘾有影响.结论 在探讨网络成瘾影响因素的同时,应关注班级背景对网络成瘾的影响.%Objective To explore the effects of class context on Internet addiction and provide evidence for the Internet addiction intervention. Methods A total of 2 898 middle school students from Wuhan and Macheng were surveyed by using of cluster sampling and were asked to fill the following scales: Internet use questionnaire, strengths and difficulties questionnaire ( Kids) , and adolescent quality of life questionnaire. Data were analyzed about the influencing factors of Internet addiction by hierarchical linear modeling. Results It was found that gender, attention deficit/hyperactivity, peer problems and adolescent quality of life had effects on Internet addiction at the student level while emotional disorder and conduct disorder had cross-level Interaction effects on Internet addiction both at student and class level. Anymore, adolescent quality of life and peer problems had negative effects on Internet addiction. Conclusion It is suggested that class context should not be neglected when studying the factors of Internet addiction among middle-school students.

  20. A hierarchical linear analysis of the effects of group variables on member exercise adherence%群体变量对成员锻炼坚持性影响的多层线性分析

    Institute of Scientific and Technical Information of China (English)

    王深; 刘一平; 王春发; 张倩

    2015-01-01

    以52个有组织的锻炼群体共601名锻炼成员为研究对象,运用分层线性模型分析技术,主要考察锻炼群体的样本特征、凝聚力、领导行为等变量,在群体水平上对成员锻炼坚持性的影响。结果表明:个体锻炼坚持性存在显著的群体差异,个体锻炼坚持性的总体变异有12.8%由群体差异造成;锻炼群体的成立时间、凝聚力与领导行为等因素是影响成员锻炼坚持性的重要群体变量;群体成立时间、群体凝聚力与领导行为,对成员锻炼坚持性的群体变异均具有较大的解释率和显著的正向预测作用。%By basing their research objects on totally 601 exercise members from 52 organized exercise groups, and by applying hierarchical linear model analysis techniques, the authors mainly examined the effects of such variables as the sample characteristic, cohesion and leading behavior of the exercise groups on member exercise adherence at the group level, and revealed the following findings: individual exercise adherence has a significant group differ-ence:12%of the total variance of individual exercise adherence is caused by group difference;such factors as exer-cise group establishment time, cohesion and leading behavior are important group variables that affect member ex-ercise adherence;group establishment time, group cohesion and leading behavior have a higher explanation rate and a significant positive prediction function on the group variance of member exercise adherence.

  1. An extensive weight-driven network with non-linear growth information

    Science.gov (United States)

    Wang, Lin; Qing Zhang, Gui; Lun Chen, Tian

    2008-12-01

    In many real-world networks such as the Internet, World Wide Web, etc., the number of edges grows in time in a nonlinear fashion. We consider growing weighted networks in which the number of outgoing edges is a nonlinear function of time and the evolution of the edges' weight is based on a mixed mechanism of weight-driven and inner selection dynamics. Moreover, two kinds of selection fashion of nodes (connected by newly established edges) have been investigated. In the common accelerating growth model, the network exhibits a wide-range power law distribution of node strengths. In the poverty alleviation model, node strength distribution can display transition from power law distribution to Poission-like distribution. The clustering coefficient, the weighted shortest path and the correlation property have been investigated simultaneously.

  2. Crystal growth and characterisation of mixed niobates for non-linear optical applications

    CERN Document Server

    Jiang, Q

    1999-01-01

    Temperature tuned NCPM has been realised by using both wavelengths. The measured phase matching temperatures increase with increasing spontaneous polarisation. KLN also has large non-linear optical coefficient (d sub 3 sub 1 =2.14 d sub 3 sub 1 sup l sup i sup N sup b sup O sup 3), a reasonably high damage threshold (1.75 times that of LiNbO sub 3), wide temperature acceptance (approx 5 deg C) and angular acceptance (approx 8 deg). Potassium sodium niobate (K sub x Na sub 1 sub - sub x NbO sub 3 , KNN) crystals have been grown and they are confirmed to be ferroelectric. However, they are unstable and break up into small pieces after a short period of time. By employing ferroelectric phenomenological theory, it is revealed that the birefringence of a ferroelectric crystal consists of two parts: one relating to a ferroelectric free of any electrical displacement and the other depending on the spontaneous polarisation. The theoretical outcomes provide a brief explanation of the experimental results in modifying ...

  3. Toxic effects of linear alkylbenzene sulfonate on metabolic activity, growth rate, and microcolony formation of Nitrosomonas and Nitrosospira strains.

    Science.gov (United States)

    Brandt, K K; Hesselsøe, M; Roslev, P; Henriksen, K; Sørensen, J

    2001-06-01

    Strong inhibitory effects of the anionic surfactant linear alkylbenzene sulfonate (LAS) on four strains of autotrophic ammonia-oxidizing bacteria (AOB) are reported. Two Nitrosospira strains were considerably more sensitive to LAS than two Nitrosomonas strains were. Interestingly, the two Nitrosospira strains showed a weak capacity to remove LAS from the medium. This could not be attributed to adsorption or any other known physical or chemical process, suggesting that biodegradation of LAS took place. In each strain, the metabolic activity (50% effective concentration [EC(50)], 6 to 38 mg liter(-1)) was affected much less by LAS than the growth rate and viability (EC(50), 3 to 14 mg liter(-1)) were. However, at LAS levels that inhibited growth, metabolic activity took place only for 1 to 5 days, after which metabolic activity also ceased. The potential for adaptation to LAS exposure was investigated with Nitrosomonas europaea grown at a sublethal LAS level (10 mg liter(-1)); compared to control cells, preexposed cells showed severely affected cell functions (cessation of growth, loss of viability, and reduced NH(4)(+) oxidation activity), demonstrating that long-term incubation at sublethal LAS levels was also detrimental. Our data strongly suggest that AOB are more sensitive to LAS than most heterotrophic bacteria are, and we hypothesize that thermodynamic constraints make AOB more susceptible to surfactant-induced stress than heterotrophic bacteria are. We further suggest that AOB may comprise a sensitive indicator group which can be used to determine the impact of LAS on microbial communities.

  4. Non-linear antigenic regions in epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) studied by EGF-TGF alpha chimaeras.

    Science.gov (United States)

    van de Poll, M L; van Rotterdam, W; Gadellaa, M M; Stortelers, C; van Vugt, M J; van Zoelen, E J

    2000-07-01

    With the help of 16 chimaeras between human epidermal growth factor (hEGF) and human transforming growth factor alpha (hTGF alpha), a detailed analysis was performed on the epitope recognized by two polyclonal antibodies raised against hEGF, and one polyclonal antibody raised against hTGF alpha. All three antibodies recognized essentially the same antigenic site, a non-linear and conformation-dependent sequence that is located near the second and fourth disulphide-bonded cysteines and that includes the start of the B-loop beta-sheet. The epitope recognized by the anti-hEGF antibodies was further characterized using 8 chimaeras between hEGF and an EGF-repeat from Drosophila Notch and was found to include Met(21), Ala(30) and Asn(32). All three polyclonal antibodies were able to neutralize the biological activity of the respective growth factor when tested on 32D murine haematopoietic progenitor cells transfected with ErbB-1, indicating that the receptor binding domain is shielded upon binding of the antibody.

  5. A high-resolution MRI study of linear growth of the human fetal skull base

    Energy Technology Data Exchange (ETDEWEB)

    Jeffery, N. [University Coll., London (United Kingdom). Dept. of Anatomy and Development Biology

    2002-04-01

    The skull base, otherwise referred to as the basicranium or cranial base, plays a key role in the process of skull development, providing both support for the brain and an architectural component of the craniofacial complex. Consequently, the fetal skull base has been the focus of numerous studies employing various methods, including sectioning, plain radiography and CT. This paper investigates high-resolution (hr) MRI as an alternative method for looking at and quantifying the fetal skull base. The evaluation tests two basic hypotheses drawn from previous studies. These suggest that the anterior segment of the midline skull base grows more rapidly than the posterior segment and that the width of the posterior cranial fossa increases disproportionately in relation to its length. I imaged 42 formalin preserved human fetuses from museum collections with hrMRI. The T2-weighted image voxels were significantly smaller than those acquired with conventional clinical MRI. Landmarks of the fetal skull base were identified on reformatted axial and sagittal images. Bivariate plots revealed that the growth rate of the anterior skull base is almost twice that of the posterior skull base and that increases in the width of the posterior cranial fossa exceed those in its length. These findings confirm those of previous investigations and show that hrMRI offers a way forward in noninvasive quantification of fetal morphology. ----------------------------------------------------------------------------.

  6. Local food supplementation and psychosocial stimulation improve linear growth and cognitive development among Indonesian infants aged 6 to 9 months.

    Science.gov (United States)

    Helmizar, Helmizar; Jalal, Fasli; Lipoeto, Nur Indrawati; Achadi, Endang L

    2017-01-01

    To evaluate the effect of culturally-relevant food supplementation and psychosocial stimulation on infant growth and development. A community-based randomized controlled trial was conducted in 40 clusters from 5 selected villages in Tanah Datar District of West Sumatera, Indonesia. We assessed 355 infants aged 6 to 9 months at the beginning of the study. The infants were divided into 4 groups: 1) Food Supplementation (FS); 2) Psychosocial Stimulation (PS); 3) Food Supplementation and Psychosocial Stimulation (FS+PS); and 4) Control Group (CG). The formula food supplement was comprised of a variety of local food sources (local MP-ASI) and adjusted for the local habits. The quality of psychosocial stimulation was assessed with the Infant HOME inventory method. Progress at 6 months was assessed by anthropometry and the Bayley scores of cognition, language and motor function. There were improvements in linear growth, cognitive and motor development of children in the FS (pcognitive development increased to 21.4±12.2 points (effect size 0.56) (pdevelopment increased to 20.7±18.4 points (effect size 0.50) (pcognitive and motor development.

  7. The growth of α-sexithiophene films on Ag(111) studied by means of PEEM with linearly polarized light.

    Science.gov (United States)

    Wagner, Thorsten; Ghanbari, Ebrahim; Huber, Daniel; Zeppenfeld, Peter

    2015-12-01

    In this study, we used photo electron emission microscopy (PEEM) to investigate the growth of α-sexithiophene (α-6 T) on Ag(111) surfaces. The experiments were carried out with linearly polarized ultraviolet-light (Hg lamp with hν=4.9 eV) in order to probe the alignment of the molecules on the surface. In particular, we acquired images before, during, and after growth while changing the polarization in a stepwise manner. For the stationary states of the clean and the α-6 T covered surfaces, we monitored the local electron yield and the intensity of the ultraviolet C-light (100-280 nm) reflected from the whole sample using PEEM and a photodiode, respectively. Due to the high ionization potential (IP>5 eV), there is no direct photoelectron emission from the organic crystallites. However, the photoelectron emission of the metal/organic interface is influenced by anisotropic absorption of the incident light beam, since the adsorbed molecules act as dichroic filters with distinct orientations. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Effects of viscosity and conductivity stratification on the linear stability and transient growth within compressible Couette flow

    Science.gov (United States)

    Saikia, Bijaylakshmi; Ramachandran, Ashwin; Sinha, Krishnendu; Govindarajan, Rama

    2017-02-01

    Accurate prediction of laminar to turbulent transition in compressible flows is a challenging task, as it can be affected by a combination of factors. Compressibility causes large variations in thermodynamic as well as transport properties of a gas, which in turn are known to affect flow stability. We study the stratification of individual transport properties and their combined behavior. We also examine the effect of a change in the magnitude of viscosity and conductivity on flow stability. The Couette flow of a perfect gas is our model problem and both modal and non-modal analyses are carried out. We notice a large destabilizing role of the increase in the conductivity value and a dramatic stabilizing effect of mean viscosity stratification, over a range of free-stream Mach number, Reynolds number, Prandtl number, and disturbance wavenumber. In the combined case, viscosity stratification plays a dominant role. We find this to be the case for finite-time transient growth in the parameter regime below linear instability as well as asymptotically at large time. A budget of the transient growth energy amplification is also shown to identify the effects of transport properties on the constituents of perturbation energy. The extensive results presented in this paper, we believe should motivate those studying more realistic flows to examine how these contrasting effects of stratification come together.

  9. Associations of Infant Feeding and Timing of Weight Gain and Linear Growth during Early Life with Childhood Blood Pressure: Findings from a Prospective Population Based Cohort Study.

    Science.gov (United States)

    de Beer, Marieke; Vrijkotte, Tanja G M; Fall, Caroline H D; van Eijsden, Manon; Osmond, Clive; Gemke, Reinoud J B J

    2016-01-01

    Small birth size and rapid postnatal growth have been associated with higher future blood pressure. The timing of these effects, the relative importance of weight gain and linear growth and the role of infant feeding need to be clarified. We assessed how blood pressure relates to birth weight, infant and childhood growth and infant feeding (duration of exclusive breastfeeding and timing of introduction of complementary feeding) in 2227 children aged 5 years from a prospective cohort study (Amsterdam Born Children and their Development). Postnatal growth was represented by statistically independent measures of relative weight gain (weight gain independent of height) and linear growth in four age periods during infancy (0-1 month; 1-3 months; 3-6 months; 6-12 months) and from 12 months to 5 years. Lower birth weight was associated with higher childhood diastolic blood pressure (-0.38 mm Hg.SD-1; P = 0.007). Faster relative weight gain and linear growth after 1 month were positively associated with systolic and diastolic blood pressure. Associations of linear growth with systolic blood pressure ranged from 0.47 to 1.49 mm Hg.SD-1; Pgrowth. Compared to breastfeeding 1 month was associated with lower blood pressure (e.g. >6 months -1.56 mm Hg systolic blood pressure; P6 months, introduction of complementary feeding pressure (e.g. 4-6 months 0.91 mm Hg systolic blood pressure; P = 0.004). After the age of one month faster growth in either weight or height is associated with higher childhood blood pressure. It is unknown whether faster weight gain and linear growth carry the same risk for adult hypertension and cardiovascular morbidity. Longer breastfeeding and delayed introduction of complementary feeding may be associated with lower adult blood pressure.

  10. Hierarchical Data Structures, Institutional Research, and Multilevel Modeling

    Science.gov (United States)

    O'Connell, Ann A.; Reed, Sandra J.

    2012-01-01

    Multilevel modeling (MLM), also referred to as hierarchical linear modeling (HLM) or mixed models, provides a powerful analytical framework through which to study colleges and universities and their impact on students. Due to the natural hierarchical structure of data obtained from students or faculty in colleges and universities, MLM offers many…

  11. Growth and characterization of nanodiamond layers prepared using the plasma-enhanced linear antennas microwave CVD system

    Energy Technology Data Exchange (ETDEWEB)

    Fendrych, Frantisek; Taylor, Andrew; Peksa, Ladislav; Kratochvilova, Irena; Kluiber, Zdenek; Fekete, Ladislav [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, CZ-18221 Prague 8 (Czech Republic); Vlcek, Jan [Department of Physics and Measurement, Institute of Chemical Technology Prague, Technicka 5, CZ-16628 Prague 6 (Czech Republic); Rezacova, Vladimira; Petrak, Vaclav [Faculty of Biomedical Engineering, Czech Technical University, Sitna 3105, CZ-27201 Kladno 2 (Czech Republic); Liehr, Michael [Leybold Optics Dresden GmbH, Zur Wetterwarte 50, D-01109 Dresden (Germany); Nesladek, Milos, E-mail: fendrych@fzu.c [IMOMEC division, IMEC, Institute for Materials Research, University Hasselt, Wetenschapspark 1, B-3590 Diepenbeek (Belgium)

    2010-09-22

    Industrial applications of plasma-enhanced chemical vapour deposition (CVD) diamond grown on large area substrates, 3D shapes, at low substrate temperatures and on standard engineering substrate materials require novel plasma concepts. Based on the pioneering work of the group at AIST in Japan, the high-density coaxial delivery type of plasmas has been explored (Tsugawa et al 2006 New Diamond Front. Carbon Technol. 16 337-46). However, an important challenge is to obtain commercially interesting growth rates at very low substrate temperatures. In this work we introduce the concept of novel linear antenna sources, designed at Leybold Optics Dresden, using high-frequency pulsed MW discharge with a high plasma density. This type of pulse discharges leads to the preparation of nanocrystalline diamond (NCD) thin films, compared with ultra-NCD thin films prepared in (Tsugawa et al 2006 New Diamond Front. Carbon Technol. 16 337-46). We present optical emission spectroscopy data for the CH{sub 4}-CO{sub 2}-H{sub 2} gas chemistry and we discuss the basic properties of the NCD films grown.

  12. Hierarchical ZnO Nanowires-loaded Sb-doped SnO2-ZnO Micrograting Pattern via Direct Imprinting-assisted Hydrothermal Growth and Its Selective Detection of Acetone Molecules.

    Science.gov (United States)

    Choi, Hak-Jong; Choi, Seon-Jin; Choo, Soyoung; Kim, Il-Doo; Lee, Heon

    2016-01-08

    We propose a novel synthetic route by combining imprinting transfer of a Sb-doped SnO2 (ATO)-ZnO composite micrograting pattern (MP), i.e., microstrip lines, on a sensor substrate and subsequent hydrothermal growth of ZnO nanowires (NWs) for producing a hierarchical ZnO NW-loaded ATO-ZnO MP as an improved chemo-resistive sensing layer. Here, ATO-ZnO MP structure with 3-μm line width, 9-μm pitch, and 6-μm height was fabricated by direct transfer of mixed ATO and ZnO nanoparticle (NP)-dispersed resists, which are pre-patterned on a polydimethylsiloxane (PDMS) mold. ZnO NWs with an average diameter of less than 50 nm and a height of 250 nm were quasi-vertically grown on the ATO-ZnO MP, leading to markedly enhanced surface area and heterojunction composites between each ATO NP, ZnO NP, and ZnO NW. A ZnO NW-loaded MP sensor with a relative ratio of 1:9 between ATO and ZnO (1:9 ATO-ZnO), exhibited highly sensitive and selective acetone sensing performance with 2.84-fold higher response (R air/R gas = 12.8) compared to that (R air/R gas = 4.5) of pristine 1:9 ATO-ZnO MP sensor at 5 ppm. Our results demonstrate the processing advantages of direct imprinting-assisted hydrothermal growth for large-scale homogeneous coating of hierarchical oxide layers, particularly for applications in highly sensitive and selective chemical sensors.

  13. Micromechanics of hierarchical materials

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon, Jr.

    2012-01-01

    A short overview of micromechanical models of hierarchical materials (hybrid composites, biomaterials, fractal materials, etc.) is given. Several examples of the modeling of strength and damage in hierarchical materials are summarized, among them, 3D FE model of hybrid composites...... with nanoengineered matrix, fiber bundle model of UD composites with hierarchically clustered fibers and 3D multilevel model of wood considered as a gradient, cellular material with layered composite cell walls. The main areas of research in micromechanics of hierarchical materials are identified, among them......, the investigations of the effects of load redistribution between reinforcing elements at different scale levels, of the possibilities to control different material properties and to ensure synergy of strengthening effects at different scale levels and using the nanoreinforcement effects. The main future directions...

  14. Hierarchical auxetic mechanical metamaterials.

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I; Azzopardi, Keith M; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N

    2015-02-11

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  15. Hierarchical Auxetic Mechanical Metamaterials

    Science.gov (United States)

    Gatt, Ruben; Mizzi, Luke; Azzopardi, Joseph I.; Azzopardi, Keith M.; Attard, Daphne; Casha, Aaron; Briffa, Joseph; Grima, Joseph N.

    2015-02-01

    Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.

  16. Applied Bayesian Hierarchical Methods

    CERN Document Server

    Congdon, Peter D

    2010-01-01

    Bayesian methods facilitate the analysis of complex models and data structures. Emphasizing data applications, alternative modeling specifications, and computer implementation, this book provides a practical overview of methods for Bayesian analysis of hierarchical models.

  17. Programming with Hierarchical Maps

    DEFF Research Database (Denmark)

    Ørbæk, Peter

    This report desribes the hierarchical maps used as a central data structure in the Corundum framework. We describe its most prominent features, ague for its usefulness and briefly describe some of the software prototypes implemented using the technology....

  18. Catalysis with hierarchical zeolites

    DEFF Research Database (Denmark)

    Holm, Martin Spangsberg; Taarning, Esben; Egeblad, Kresten

    2011-01-01

    Hierarchical (or mesoporous) zeolites have attracted significant attention during the first decade of the 21st century, and so far this interest continues to increase. There have already been several reviews giving detailed accounts of the developments emphasizing different aspects of this research...... topic. Until now, the main reason for developing hierarchical zeolites has been to achieve heterogeneous catalysts with improved performance but this particular facet has not yet been reviewed in detail. Thus, the present paper summaries and categorizes the catalytic studies utilizing hierarchical...... zeolites that have been reported hitherto. Prototypical examples from some of the different categories of catalytic reactions that have been studied using hierarchical zeolite catalysts are highlighted. This clearly illustrates the different ways that improved performance can be achieved with this family...

  19. Growth of 3D hierarchical porous NiO@carbon nanoflakes on graphene sheets for high-performance lithium-ion batteries.

    Science.gov (United States)

    Wang, Xiongwei; Zhang, Ludan; Zhang, Zehui; Yu, Aishui; Wu, Peiyi

    2016-02-07

    Nickel oxide (NiO) as one of the anode electrode materials for lithium ion batteries (LIBs) has attracted considerable research attention. However, the poor electron conductivity and bad capacity retention performance greatly hinder its wide application. Herein, we prepared a novel three-dimensional (3D) hierarchical porous graphene@NiO@carbon composite via a simple solvothermal process, in which the graphene sheets were uniformly wrapped by porous NiO@carbon nanoflakes. In this case, nickelocene was creatively used as the precursor for both NiO and amorphous carbon, while graphene oxide sheets were employed as a template for the two-dimensional nanostructure and the conductive graphene backbone. The resultant composites possess high surface area (196 m(2) g(-1)) and large pore volume (0.46 cm(3) g(-1)). When it is applied as an anode for LIBs, the carbon outer-layer can effectively suppress the large volume change and serious aggregation of NiO nanoparticles during the charge-discharge process. Therefore, the graphene@NiO@carbon composites show a high reversible capacity of 1042 mA h g(-1) at a current density of 200 mA g(-1), an excellent rate performance and long cycle life. We believe that our method provides a new route for the fabrication of novel transition metal oxide composites.

  20. Avaliação do crescimento linear de crianças e adolescentes com asma Linear growth evaluation of asthmatic children

    Directory of Open Access Journals (Sweden)

    MARIA ÂNGELA G. MONTEIRO-ANTONIO

    2002-06-01

    Full Text Available OBJETIVO: Estudar a influência da asma atópica sobre a estatura e a velocidade de crescimento em crianças e adolescentes brasileiros, considerando as condições socioeconômicas, a história natural da doença e o crescimento individual. MÉTODOS: Foram acompanhados 66 pacientes do Ambulatório de Imunologia, Alergia e Pneumologia do Hospital das Clínicas da Universidade Estadual de Campinas (HC/Unicamp, com idade entre 4 e 14 anos completos. A altura foi medida ao início do estudo e a cada três meses, e a idade óssea realizada uma vez durante o período de observação. Os pacientes foram divididos em dois grupos de acordo com o desenvolvimento puberal: pré-púbere e púbere. RESULTADOS: Nos 40 pacientes do grupo pré-púbere, com seguimento de 0,5 - 1,3 anos, a média dos escores z da altura/idade foi 0,028±0,978 e a da velocidade de crescimento foi 0,045±1,110. Os 26 pacientes do grupo púbere, com seguimento de 0,6 - 1,5 anos, tiveram a média dos escores z da altura/idade de -0,170±1,209 e a da velocidade de crescimento de -0,042±2,321. No grupo pré-púbere, os pacientes que tiveram uma ou mais pneumonias, apresentaram menor média do escore z da velocidade de crescimento (p=0,04, enquanto nos pacientes púberes, o mesmo se observou em relação ao uso de corticosteróides em dose alta (p=0,02. CONCLUSÕES: O manejo correto da asma, associado ao controle das infecções e à condições de vida favoráveis, permitem que as crianças e adolescentes cresçam normalmente, atingindo seu potencial genético pleno.OBJETIVE: The aim was to assess the effect of atopic asthma on the stature and growth velocity of Brazilian adolescents and children, taking into consideration their socioeconomic conditions, natural disease history and individual growth .METHODS: 66 patients had been seen at the Pneumology, Immunology and Allergy Ambulatory, Unicamp, University Hospital. Their height and weight were measured every 3 months and the bone

  1. Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

    Science.gov (United States)

    Schwarz, L.K.; Runge, M.C.

    2009-01-01

    Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

  2. Semiparametric Quantile Modelling of Hierarchical Data

    Institute of Scientific and Technical Information of China (English)

    Mao Zai TIAN; Man Lai TANG; Ping Shing CHAN

    2009-01-01

    The classic hierarchical linear model formulation provides a considerable flexibility for modelling the random effects structure and a powerful tool for analyzing nested data that arise in various areas such as biology, economics and education. However, it assumes the within-group errors to be independently and identically distributed (i.i.d.) and models at all levels to be linear. Most importantly, traditional hierarchical models (just like other ordinary mean regression methods) cannot characterize the entire conditional distribution of a dependent variable given a set of covariates and fail to yield robust estimators. In this article, we relax the aforementioned and normality assumptions, and develop a so-called Hierarchical Semiparametric Quantile Regression Models in which the within-group errors could be heteroscedastic and models at some levels are allowed to be nonparametric. We present the ideas with a 2-level model. The level-l model is specified as a nonparametric model whereas level-2 model is set as a parametric model. Under the proposed semiparametric setting the vector of partial derivatives of the nonparametric function in level-1 becomes the response variable vector in level 2. The proposed method allows us to model the fixed effects in the innermost level (i.e., level 2) as a function of the covariates instead of a constant effect. We outline some mild regularity conditions required for convergence and asymptotic normality for our estimators. We illustrate our methodology with a real hierarchical data set from a laboratory study and some simulation studies.

  3. Micromolar Cd2+ affects the growth, hierarchical structure and peptide composition of the biosilica of the freshwater diatom Nitzschia palea (Kutzing) W. Smith

    NARCIS (Netherlands)

    Heredia, Alejandro; Figueira, Etelvina; Rodrigues, Carina T.; Rodriguez-Galvan, Andres; Basiuk, Vladimir A.; Vrieling, Engel G.; Almeida, Salome F. P.

    2012-01-01

    Biosilica from diatoms is formed at ambient conditions under the control of biological and physicochemical processes. The changes in growth and biosilica formation through uptake of different concentrations of Cd2+ by the diatom Nitzschia palea (Kutzing) W. Smith was investigated, correlating Cd2+ e

  4. Neutrosophic Hierarchical Clustering Algoritms

    Directory of Open Access Journals (Sweden)

    Rıdvan Şahin

    2014-03-01

    Full Text Available Interval neutrosophic set (INS is a generalization of interval valued intuitionistic fuzzy set (IVIFS, whose the membership and non-membership values of elements consist of fuzzy range, while single valued neutrosophic set (SVNS is regarded as extension of intuitionistic fuzzy set (IFS. In this paper, we extend the hierarchical clustering techniques proposed for IFSs and IVIFSs to SVNSs and INSs respectively. Based on the traditional hierarchical clustering procedure, the single valued neutrosophic aggregation operator, and the basic distance measures between SVNSs, we define a single valued neutrosophic hierarchical clustering algorithm for clustering SVNSs. Then we extend the algorithm to classify an interval neutrosophic data. Finally, we present some numerical examples in order to show the effectiveness and availability of the developed clustering algorithms.

  5. Quantum transport through hierarchical structures.

    Science.gov (United States)

    Boettcher, S; Varghese, C; Novotny, M A

    2011-04-01

    The transport of quantum electrons through hierarchical lattices is of interest because such lattices have some properties of both regular lattices and random systems. We calculate the electron transmission as a function of energy in the tight-binding approximation for two related Hanoi networks. HN3 is a Hanoi network with every site having three bonds. HN5 has additional bonds added to HN3 to make the average number of bonds per site equal to five. We present a renormalization group approach to solve the matrix equation involved in this quantum transport calculation. We observe band gaps in HN3, while no such band gaps are observed in linear networks or in HN5. We provide a detailed scaling analysis near the edges of these band gaps.

  6. Bayesian hierarchical modeling of drug stability data.

    Science.gov (United States)

    Chen, Jie; Zhong, Jinglin; Nie, Lei

    2008-06-15

    Stability data are commonly analyzed using linear fixed or random effect model. The linear fixed effect model does not take into account the batch-to-batch variation, whereas the random effect model may suffer from the unreliable shelf-life estimates due to small sample size. Moreover, both methods do not utilize any prior information that might have been available. In this article, we propose a Bayesian hierarchical approach to modeling drug stability data. Under this hierarchical structure, we first use Bayes factor to test the poolability of batches. Given the decision on poolability of batches, we then estimate the shelf-life that applies to all batches. The approach is illustrated with two example data sets and its performance is compared in simulation studies with that of the commonly used frequentist methods. (c) 2008 John Wiley & Sons, Ltd.

  7. Newborn length predicts early infant linear growth retardation and disproportionately high weight gain in a low-income population1-2

    Science.gov (United States)

    Berngard, S Clark; Berngard, Jennifer Bishop; Krebs, Nancy F; Garcés, Ana; Miller, Leland V; Westcott, Jamie; Wright, Linda L; Kindem, Mark; Hambidge, K Michael

    2013-01-01

    Background Stunting is prevalent by the age of 6 mo in the indigenous population of the Western Highlands of Guatemala. Aim The objective of this study was to determine the time course and predictors of linear growth failure and weight-for-age in early infancy. Study Design and Subjects One hundred and forty eight term newborns had measurements of length and weight in their homes, repeated at 3 and 6 mo. Maternal measurements were also obtained. Results Mean ± SD length-for-age Z-score (LAZ) declined from newborn -1.0 (1.01) to -2.20 (1.05) and -2.26 (1.01) at 3 and 6 mo respectively. Stunting rates for newborn, 3 and 6 mo were 47%, 53% and 56% respectively. A multiple regression model (R2 = 0.64) demonstrated that the major predictor of LAZ at 3 mo was newborn LAZ with the other predictors being newborn weight-for-age Z-score (WAZ), gender and maternal education*maternal age interaction. Because WAZ remained essentially constant and LAZ declined during the same period, weight-for-length Z-score (WLZ) increased from -0.44 to +1.28 from birth to 3 mo. The more severe the linear growth failure, the greater WAZ was in proportion to the LAZ. Conclusion The primary conclusion is that impaired fetal linear growth is the major predictor of early infant linear growth failure indicating that prevention needs to start with maternal interventions. PMID:24083893

  8. 重複觀測量數之分析:多群體多變項線性成長模式的估計Data Analysis of Repeated Measures: Estimating a Multi-Group Multivariate Linear Growth Model

    Directory of Open Access Journals (Sweden)

    溫福星 Fur-Hsing Wen

    2012-03-01

    Full Text Available 本研究利用「台灣教育長期追蹤資料庫」的一般分析能力與數學分析能力的四波調查結果,配合男、女學生樣本進行多群體多條追蹤資料的線性成長模式估計。在考慮重複觀測資料誤差項在不同時點的變異數非同質與不同時點間的共變數非獨立情況下,以及男、女學生的不同成長軌跡,將誤差項結構設為無限制結構,利用虛擬變項交互項法與虛擬變項多樣本法同時估計不同性別、不同能力的線性成長軌跡變化。由於全部追蹤資料樣本存在遺失值的情形,本研究以階層線性模式(hierarchical linear modeling, HLM)軟體對完整資料2,806位學生進行分析,其估計結果發現,在完整資料的兩條成長軌跡模式中,男、女學生誤差項共變異數矩陣結構相同,但線性成長軌跡不恆等。除此之外,本文並對競爭模式比較的結果在文章最後進行討論並提出相關的建議。 This paper demonstrates the data analysis of the repeated measures from the Taiwan Education Panel Survey (TEPS. Based on the four data waves on the TEPS, we consider two abilities (general and mathematic and two population groups (male and female students to construct a multi-group multivariate linear growth model. Because the two-group multivariate repeated measures belong to the different populations and the different research variables, the residual terms of linear growth models may imply heterogeneity of the error covariance structure. We treat the error covariance structure as an unrestricted structure to compare the various types of models. The results from the HLM on the complete data (2,806 students reveal that the male and female students in this study have the same error covariance structure but have distinct linear growth trajectories. In addition, comparisons of the competitive models and related suggestions are discussed in the results and conclusion

  9. The effect of folic acid supplementation with ferrous sulfate on the linear and ponderal growth of children aged 6-24 months: a randomized controlled trial.

    Science.gov (United States)

    Medeiros, D A; Hadler, M C C M; Sugai, A; Torres, V M

    2015-02-01

    Studies evaluating the effect of folic acid supplementation, either alone or in combination with iron, on the linear and ponderal growth of children are practically nonexistent. The aim of this study was to assess the effect of folic acid supplementation with ferrous sulfate on both linear growth and weight gain in anemic and nonanemic children attending Municipal Daycare Centers in Goiania, State of Goias, Brazil. A double-blind, randomized, controlled trial was conducted on 188 children aged 6-24 months. The effects of ferrous sulfate and folic acid supplementation were evaluated using the analysis of variance procedure, based on a double factorial model with two factors of fixed effects (folic acid supplementation and ferrous sulfate supplementation), adjusted for initial weight. The level of significance was 0.05. The children who received folic acid supplementation showed greater weight gain than the monthly average weight gain of those not given the supplement (P=0.026). This effect was independent of the dose of ferrous sulfate (P for interaction=0.693). Folic acid supplementation increased the gain of weight-for-age Z-score when compared with the placebo group (P=0.018), independent of the dose of ferrous sulfate. Folic acid had no effect on linear growth. The use of folic acid supplementation increased the monthly average weight gain and the gain in weight-for-age Z-score compared with the placebo group. This effect was independent of the dose of ferrous sulfate.

  10. Strategic games on a hierarchical network model

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Among complex network models, the hierarchical network model is the one most close to such real networks as world trade web, metabolic network, WWW, actor network, and so on. It has not only the property of power-law degree distribution, but growth based on growth and preferential attachment, showing the scale-free degree distribution property. In this paper, we study the evolution of cooperation on a hierarchical network model, adopting the prisoner's dilemma (PD) game and snowdrift game (SG) as metaphors of the interplay between connected nodes. BA model provides a unifying framework for the emergence of cooperation. But interestingly, we found that on hierarchical model, there is no sign of cooperation for PD game, while the frequency of cooperation decreases as the common benefit decreases for SG. By comparing the scaling clustering coefficient properties of the hierarchical network model with that of BA model, we found that the former amplifies the effect of hubs. Considering different performances of PD game and SG on complex network, we also found that common benefit leads to cooperation in the evolution. Thus our study may shed light on the emergence of cooperation in both natural and social environments.

  11. On the spatial linear growth of gravity-capillary water waves sheared by a laminar air flow

    NARCIS (Netherlands)

    Tsai, Y.S.; Grass, A.J.; Simons, R.R.

    2005-01-01

    The initial growth of mechanically generated small amplitude water waves below a laminar air stream was examined numerically and experimentally in order to explore the primary growth mechanism, that is, the interfacial instability of coupled laminar air and water flows. Measurements of the laminar v

  12. Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-07

    Materials Design is often at the forefront of technological innovation. While there has always been a push to generate increasingly low density materials, such as aero or hydrogels, more recently the idea of bicontinuous structures has gone more into play. This review will cover some of the methods and applications for generating both porous, and hierarchically porous structures.

  13. Universality: Accurate Checks in Dyson's Hierarchical Model

    Science.gov (United States)

    Godina, J. J.; Meurice, Y.; Oktay, M. B.

    2003-06-01

    In this talk we present high-accuracy calculations of the susceptibility near βc for Dyson's hierarchical model in D = 3. Using linear fitting, we estimate the leading (γ) and subleading (Δ) exponents. Independent estimates are obtained by calculating the first two eigenvalues of the linearized renormalization group transformation. We found γ = 1.29914073 ± 10 -8 and, Δ = 0.4259469 ± 10-7 independently of the choice of local integration measure (Ising or Landau-Ginzburg). After a suitable rescaling, the approximate fixed points for a large class of local measure coincide accurately with a fixed point constructed by Koch and Wittwer.

  14. Bias factors associated with assessing the validity of university teaching: a hierarchical linear model Factores de sesgo asociados a la validez de la evaluación docente universitaria: un modelo jerárquico lineal.

    Directory of Open Access Journals (Sweden)

    Raciel Acevedo Alvarez

    2006-12-01

    Full Text Available The present study analyzes the variables that are intrinsically linked with the student, professor and class environment in relation to the university educational evaluation questionnaires. The participants in the study were 374 students with an age mean of 19.9 and 29 professors with an age mean of 36 from 3 different departments at the Universidad de Costa Rica (UCR at the city of Guanacaste. The hierarchical lineal models were used for the data analysis, a quantitative methodology which facilitates the evaluation of the determinants which affect the results of the study. However, only four of these determinants were associated with the evaluation concerned, class size, enrolment year, department type and forecasted achievement levels. The results obtained from the study demonstrate that these kinds of evaluation are valid despite the results being slightly affected by a range of factors from externalities to teacher competence. El presente estudio analiza las variables del estudiante, la clase y el profesor asociadas con el sesgo en los cuestionarios aplicados a los estudiantes en la evaluación docente universitaria. En la propuesta han participado 374 estudiantes y 29 profesores de tres departamentos de la Universidad de Costa Rica (UCR, sede de Guanacaste, con una media de edad de 19.9 para los estudiantes y de 36 años los profesores. Para el análisis de los datos se utilizaron los modelos jerárquicos lineales, una metodología cuantitativa, cuyas estimaciones permitieron comprobar que de todos los determinantes incluidos en el estudio, solamente, cuatro de ellos (número de estudiantes en el curso, cantidad de años en la institución, tipo de departamento al que pertenece el estudiante y expectativa de nota estaban ligeramente asociados a este tipo de evaluación. Los resultados demuestran que estas evaluaciones son válidas y se ven poco afectadas por los elementos externos a la competencia docente.

  15. Oriented attachment growth of BiOCl nanosheets with exposed {l_brace}1 1 0{r_brace} facets and photocatalytic activity of the hierarchical nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhankui, E-mail: zkcui@foxmail.com [Key Laboratory of Micro-Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, Xuchang University, Xuchang 461000 (China); Mi, Liwei [Key Laboratory of Micro-Nano Materials for Energy Storage and Conversion of Henan Province, Institute of Surface Micro and Nano Materials, Xuchang University, Xuchang 461000 (China); Zeng, Dawen [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-02-05

    Highlights: Black-Right-Pointing-Pointer Growth of BiOCl nanosheets in EG medium was experimentally revealed. Black-Right-Pointing-Pointer Oriented attachment mechanism governed formation of single crystalline BiOCl. Black-Right-Pointing-Pointer The exposed facets of BiOCl nanosheets were {l_brace}1 1 0{r_brace} planes. Black-Right-Pointing-Pointer The samples could efficiently degrade MO irradiated either by UV or by Vis. Black-Right-Pointing-Pointer The high efficiency was associated with the exposed {l_brace}1 1 0{r_brace} facets of BiOCl. - Abstract: The formation mechanism of nanosheet assembled BiOCl nanostructures in non-aqueous solvothermal system was investigated through time series experiments. The products obtained at different reaction times were characterized by XRD, SEM and (HR)TEM techniques. The photocatalytic property of the samples was measured by decomposing the organic dye of methyl orange. The ability to generate hydroxyl radicals for the samples was also measured by photoluminescence method using coumarin as fluorescence probe molecules. It was revealed that oriented attachment was responsible for the slow transformation of BiOCl from polycrystalline nanoparticles to single crystalline nanosheets. The role of the solvent ethylene glycol and the interaction with the other species during the oriented attachment growth of the BiOCl nanosheets was discussed. The photocatalytic activity tests demonstrated that the BiOCl nanostructures could efficiently decompose methyl orange under either UV light irradiation or visible light irradiation. The high photodegradation efficiency was associated with the atomic arrangement of exposed {l_brace}1 1 0{r_brace} facets.

  16. The Joint Trajectory of Adolescent Aggression: An Application of Hierarchical Multivariate Linear Model%青少年攻击行为的发展及家庭体罚的影响

    Institute of Scientific and Technical Information of China (English)

    吴鹏; 刘华山; 姜春艳; 马玉芝

    2012-01-01

    Objective: To display the joint trajectory of three forms of aggression among adolescents, to explore the gender difference in the growth of adolescent aggression and the role of corpora] punishment. Methods: Three aggression forms were assessed 4 times in a year. 294 junior middle school students attended this longitudinal study and the data was analyzed through mulvariate HLM. Results: ①'There was a significant negative slope in the growth model of physical aggression and a significant gender difference in the growth model. ②The slope correlated positively to the intercept in growth of physical aggression. ③The corporal punishment can predict the intercept of three growth model. Conclusion: There is a significant growth in adolescent's physical aggression and a gender difference in the developmental tendency. Boys display more rapid increase in the development of physical aggression. The intercept of the physical aggression growth is correlated positively with the slope of the growth and the relational aggression has the same correlation. Corporal punishment would affect the intercept of the physical aggression, the relational aggression and the verbal aggression.%目的:探讨青少年三种攻击行为的共同发展趋势和性别差异,分析家庭体罚对青少年攻击的影响.方法:使用Bjorkquist 等人编制的DIA量表和Strauss等人编制的CTSPC问卷追踪测查294名初中生的攻击行为和家庭体罚,采用多元多层线性模型分析了青少年身体攻击、关系攻击和言语攻击的整体发展状况及相互影响.结果:①青少年身体攻击增长率显著,男生的增长率显著高于女生;②身体攻击增长模型的斜率和截距有显著正相关:③家庭体罚能显著正向影响三种攻击增长模型的截距,但不会影响其斜率.结论:青少年身体攻击呈增长趋势,男生增长更快,家庭体罚可以影响青少年的攻击行为.

  17. Linear and Ponderal Growth Trajectories in Well-Nourished, Iron-Sufficient Infants Are Unimpaired by Iron Supplementation12

    OpenAIRE

    2009-01-01

    Iron deficiency remains the most common nutritional deficiency worldwide and supplementation is recommended during periods of high risk, including infancy. However, questions have been raised about possible adverse effects of iron on growth in iron-sufficient (IS) infants and the advisability of across-the-board iron supplementation. This study examined whether short- or long-term growth was impaired in IS infants who received iron supplementation. From a longitudinal study of healthy, breast...

  18. Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

    Directory of Open Access Journals (Sweden)

    Schneider Andreas S

    2012-09-01

    Full Text Available Abstract Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM [Gilbert et al., Journal of the

  19. Recombinant human growth hormone treatment, using two dose regimens in children with chronic renal failure--a report on linear growth and adverse effects

    DEFF Research Database (Denmark)

    Hertel, Niels Thomas; Holmberg, Christer; Rönnholm, Kai A R

    2002-01-01

    The aim of this study was to study the efficiency and the adverse effects of 2 or 4 IU/m2/day of growth hormone (GH) in the first year and 4 IU/m2/day in the second. Of 29 growth-retarded children with chronic renal failure (CRF) (aged 3.4-15.1 years), 23 completed the first year of therapy, and 16...

  20. Image meshing via hierarchical optimization

    Institute of Scientific and Technical Information of China (English)

    Hao XIE; Ruo-feng TONG‡

    2016-01-01

    Vector graphic, as a kind of geometric representation of raster images, has many advantages, e.g., defi nition independence and editing facility. A popular way to convert raster images into vector graphics is image meshing, the aim of which is to fi nd a mesh to represent an image as faithfully as possible. For traditional meshing algorithms, the crux of the problem resides mainly in the high non-linearity and non-smoothness of the objective, which makes it difficult to fi nd a desirable optimal solution. To ameliorate this situation, we present a hierarchical optimization algorithm solving the problem from coarser levels to fi ner ones, providing initialization for each level with its coarser ascent. To further simplify the problem, the original non-convex problem is converted to a linear least squares one, and thus becomes convex, which makes the problem much easier to solve. A dictionary learning framework is used to combine geometry and topology elegantly. Then an alternating scheme is employed to solve both parts. Experiments show that our algorithm runs fast and achieves better results than existing ones for most images.

  1. Image meshing via hierarchical optimization*

    Institute of Scientific and Technical Information of China (English)

    Hao XIE; Ruo-feng TONGS

    2016-01-01

    Vector graphic, as a kind of geometric representation of raster images, has many advantages, e.g., definition independence and editing facility. A popular way to convert raster images into vector graphics is image meshing, the aim of which is to find a mesh to represent an image as faithfully as possible. For traditional meshing algorithms, the crux of the problem resides mainly in the high non-linearity and non-smoothness of the objective, which makes it difficult to find a desirable optimal solution. To ameliorate this situation, we present a hierarchical optimization algorithm solving the problem from coarser levels to finer ones, providing initialization for each level with its coarser ascent. To further simplify the problem, the original non-convex problem is converted to a linear least squares one, and thus becomes convex, which makes the problem much easier to solve. A dictionary learning framework is used to combine geometry and topology elegantly. Then an alternating scheme is employed to solve both parts. Experiments show that our algorithm runs fast and achieves better results than existing ones for most images.

  2. Growth, Structure, and Photocatalytic Properties of Hierarchical V₂O₅-TiO₂ Nanotube Arrays Obtained from the One-step Anodic Oxidation of Ti-V Alloys.

    Science.gov (United States)

    Nevárez-Martínez, María C; Mazierski, Paweł; Kobylański, Marek P; Szczepańska, Grażyna; Trykowski, Grzegorz; Malankowska, Anna; Kozak, Magda; Espinoza-Montero, Patricio J; Zaleska-Medynska, Adriana

    2017-04-05

    V₂O₅-TiO₂ mixed oxide nanotube (NT) layers were successfully prepared via the one-step anodization of Ti-V alloys. The obtained samples were characterized by scanning electron microscopy (SEM), UV-Vis absorption, photoluminescence spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (DRX), and micro-Raman spectroscopy. The effect of the applied voltage (30-50 V), vanadium content (5-15 wt %) in the alloy, and water content (2-10 vol %) in an ethylene glycol-based electrolyte was studied systematically to determine their influence on the morphology, and for the first-time, on the photocatalytic properties of these nanomaterials. The morphology of the samples varied from sponge-like to highly-organized nanotubular structures. The vanadium content in the alloy was found to have the highest influence on the morphology and the sample with the lowest vanadium content (5 wt %) exhibited the best auto-alignment and self-organization (length = 1 μm, diameter = 86 nm and wall thickness = 11 nm). Additionally, a probable growth mechanism of V₂O₅-TiO₂ nanotubes (NTs) over the Ti-V alloys was presented. Toluene, in the gas phase, was effectively removed through photodegradation under visible light (LEDs, λmax = 465 nm) in the presence of the modified TiO₂ nanostructures. The highest degradation value was 35% after 60 min of irradiation. V₂O₅ species were ascribed as the main structures responsible for the generation of photoactive e(-) and h⁺ under Vis light and a possible excitation mechanism was proposed.

  3. Hierarchical manifold learning.

    Science.gov (United States)

    Bhatia, Kanwal K; Rao, Anil; Price, Anthony N; Wolz, Robin; Hajnal, Jo; Rueckert, Daniel

    2012-01-01

    We present a novel method of hierarchical manifold learning which aims to automatically discover regional variations within images. This involves constructing manifolds in a hierarchy of image patches of increasing granularity, while ensuring consistency between hierarchy levels. We demonstrate its utility in two very different settings: (1) to learn the regional correlations in motion within a sequence of time-resolved images of the thoracic cavity; (2) to find discriminative regions of 3D brain images in the classification of neurodegenerative disease,

  4. Hierarchically Structured Electrospun Fibers

    Directory of Open Access Journals (Sweden)

    Nicole E. Zander

    2013-01-01

    Full Text Available Traditional electrospun nanofibers have a myriad of applications ranging from scaffolds for tissue engineering to components of biosensors and energy harvesting devices. The generally smooth one-dimensional structure of the fibers has stood as a limitation to several interesting novel applications. Control of fiber diameter, porosity and collector geometry will be briefly discussed, as will more traditional methods for controlling fiber morphology and fiber mat architecture. The remainder of the review will focus on new techniques to prepare hierarchically structured fibers. Fibers with hierarchical primary structures—including helical, buckled, and beads-on-a-string fibers, as well as fibers with secondary structures, such as nanopores, nanopillars, nanorods, and internally structured fibers and their applications—will be discussed. These new materials with helical/buckled morphology are expected to possess unique optical and mechanical properties with possible applications for negative refractive index materials, highly stretchable/high-tensile-strength materials, and components in microelectromechanical devices. Core-shell type fibers enable a much wider variety of materials to be electrospun and are expected to be widely applied in the sensing, drug delivery/controlled release fields, and in the encapsulation of live cells for biological applications. Materials with a hierarchical secondary structure are expected to provide new superhydrophobic and self-cleaning materials.

  5. HDS: Hierarchical Data System

    Science.gov (United States)

    Pearce, Dave; Walter, Anton; Lupton, W. F.; Warren-Smith, Rodney F.; Lawden, Mike; McIlwrath, Brian; Peden, J. C. M.; Jenness, Tim; Draper, Peter W.

    2015-02-01

    The Hierarchical Data System (HDS) is a file-based hierarchical data system designed for the storage of a wide variety of information. It is particularly suited to the storage of large multi-dimensional arrays (with their ancillary data) where efficient access is needed. It is a key component of the Starlink software collection (ascl:1110.012) and is used by the Starlink N-Dimensional Data Format (NDF) library (ascl:1411.023). HDS organizes data into hierarchies, broadly similar to the directory structure of a hierarchical filing system, but contained within a single HDS container file. The structures stored in these files are self-describing and flexible; HDS supports modification and extension of structures previously created, as well as functions such as deletion, copying, and renaming. All information stored in HDS files is portable between the machines on which HDS is implemented. Thus, there are no format conversion problems when moving between machines. HDS can write files in a private binary format (version 4), or be layered on top of HDF5 (version 5).

  6. Hierarchical video summarization

    Science.gov (United States)

    Ratakonda, Krishna; Sezan, M. Ibrahim; Crinon, Regis J.

    1998-12-01

    We address the problem of key-frame summarization of vide in the absence of any a priori information about its content. This is a common problem that is encountered in home videos. We propose a hierarchical key-frame summarization algorithm where a coarse-to-fine key-frame summary is generated. A hierarchical key-frame summary facilitates multi-level browsing where the user can quickly discover the content of the video by accessing its coarsest but most compact summary and then view a desired segment of the video with increasingly more detail. At the finest level, the summary is generated on the basis of color features of video frames, using an extension of a recently proposed key-frame extraction algorithm. The finest level key-frames are recursively clustered using a novel pairwise K-means clustering approach with temporal consecutiveness constraint. We also address summarization of MPEG-2 compressed video without fully decoding the bitstream. We also propose efficient mechanisms that facilitate decoding the video when the hierarchical summary is utilized in browsing and playback of video segments starting at selected key-frames.

  7. Synthesis and Characterization of ZnTe Hierarchical Nanostructures

    Directory of Open Access Journals (Sweden)

    Baohua Zhang

    2012-01-01

    Full Text Available Single-crystalline ZnTe hierarchical nanostructures have been successfully synthesized by a simple thermal evaporation technology. The as-prepared products were characterized with X-ray diffraction (XRD, scanning electron microcopy (SEM, transmission electron microscope (TEM, and photoluminescence spectrum (PL. These results showed that the ZnTe hierarchical nanostructures consisted of nanowires and nanolumps. The room temperature PL spectrum exhibited a pure green luminescence centered at 545nm. The growth mechanism of hierarchical nanostructure was also discussed.

  8. Rational design of hierarchically-structured CuBi2O4 composites by deliberate manipulation of the nucleation and growth kinetics of CuBi2O4 for environmental applications

    Science.gov (United States)

    Oh, Wen-Da; Lua, Shun-Kuang; Dong, Zhili; Lim, Teik-Thye

    2016-01-01

    A versatile, eco-friendly synthesis scheme was developed to fabricate a series of hierarchically-structured CuBi2O4 composites for environmental applications. By simple tuning of the synthesis protocol (i.e. controlling the ethylene glycol to water ratio in the reaction matrix and employing different auxiliary metal precursors consisting of Cu2+, Co2+ or Fe3+ species), deposition of various metal oxides on CuBi2O4 was achieved. The proposed one-pot synthesis protocol utilizes the fast nucleation and controlled growth kinetics of CuBi2O4 to deliberately immobilize the desired metal oxides on the surface of the CuBi2O4. The manipulation of the diffusion rate, mass transfer kinetics and atomic mobility of the metal precursors by controlling the viscosity and dielectric properties of the reaction matrix lead to the formation of different CuBi2O4 composites with the desired properties. The synergistic coupling effect between the CuBi2O4 and deposited metal oxide contributed to the superior performance of the novel CuBi2O4 composites. The CuBi2O4 composites demonstrate excellent potential for various environmental applications such as being a catalyst for generating sulfate radicals from peroxymonosulfate for organic pollutant removal in water and being a disinfectant. The proposed green synthesis protocol is simple and offers flexibility for fabricating hierarchically-structured CuBi2O4 composites with enhanced properties for targeted applications.A versatile, eco-friendly synthesis scheme was developed to fabricate a series of hierarchically-structured CuBi2O4 composites for environmental applications. By simple tuning of the synthesis protocol (i.e. controlling the ethylene glycol to water ratio in the reaction matrix and employing different auxiliary metal precursors consisting of Cu2+, Co2+ or Fe3+ species), deposition of various metal oxides on CuBi2O4 was achieved. The proposed one-pot synthesis protocol utilizes the fast nucleation and controlled growth kinetics

  9. Association of Linear Growth Impairment in Pediatric Crohn's Disease and a Known Height Locus: A Pilot Study

    NARCIS (Netherlands)

    J.J. Lee (Jessica); J.B. Essers (Jonah); S. Kugathasan (Subra); J.C. Escher (Johanna); G. Lettre (Guillaume); J.L. Butler (Johannah); M.C. Stephens (Michael); M.F. Ramoni (Marco); R.J. Grand (Richard); J.N. Hirschhorn (Joel)

    2010-01-01

    textabstractThe etiology of growth impairment in Crohn's disease (CD) has been inadequately explained by nutritional, hormonal, and/or disease-related factors, suggesting that genetics may be an additional contributor. The aim of this cross-sectional study was to investigate genetic variants associa

  10. Linear growth, growth-hormone secretion and IGF-I generation in children with neglected hypothyroidism before and after thyroxine replacement.

    Science.gov (United States)

    Soliman, Ashraf T; Omar, Magdy; El Awwa, Ahmad; Rizk, Mostafa M; El Alaily, Rania K; Bedair, Elsaid M A

    2008-10-01

    We studied growth hormone (GH) stimulation and insulin-like growth factor -I (IGF-I) generation tests in 15 children with neglected congenital hypothyroidism (CH) (age = 6.4 +/- 4.2 years) and measured their growth parameters for >1 years after starting thyroxine (T4) replacement. One year after treatment, height SDS (HtSDS) increased from -4.3 +/- 2.5 to -2.7 +/- 2.3. Peak GH response to clonidine increased from 3.2 +/- 1.2 ng ml(-1) to 7.62 +/- 1.38 ng ml(-1) after treatments. Basal and peak IGF-I response to GH increased from (34.66 +/- 17.3 ng ml(-1) and 58.4 +/- 36.99 ng ml(-1), respectively) before treatment to (130.6 +/- 97.8 ng ml(-1) and 193.75 +/- 122.5 ng ml(-1), respectively). HtSDS increments were correlated significantly with basal free T4 concentrations (r = 0.622, P < 0.01). In summary, after long period of hypothyroidism, T4 replacement produced significant, although incomplete, catch-up growth through a partial recovery of GH- IGF-I axis.

  11. Hierarchical Boltzmann simulations and model error estimation

    Science.gov (United States)

    Torrilhon, Manuel; Sarna, Neeraj

    2017-08-01

    A hierarchical simulation approach for Boltzmann's equation should provide a single numerical framework in which a coarse representation can be used to compute gas flows as accurately and efficiently as in computational fluid dynamics, but a subsequent refinement allows to successively improve the result to the complete Boltzmann result. We use Hermite discretization, or moment equations, for the steady linearized Boltzmann equation for a proof-of-concept of such a framework. All representations of the hierarchy are rotationally invariant and the numerical method is formulated on fully unstructured triangular and quadrilateral meshes using a implicit discontinuous Galerkin formulation. We demonstrate the performance of the numerical method on model problems which in particular highlights the relevance of stability of boundary conditions on curved domains. The hierarchical nature of the method allows also to provide model error estimates by comparing subsequent representations. We present various model errors for a flow through a curved channel with obstacles.

  12. Scaling-Up Access to Family Planning May Improve Linear Growth and Child Development in Low and Middle Income Countries

    OpenAIRE

    Günther Fink; Sudfeld, Christopher R.; Goodarz Danaei; Majid Ezzati; Wafaie W Fawzi

    2014-01-01

    Background: A large literature has indicated a robust association between birth spacing and child survival, but evidence on the association of birth timing with physical growth in low and middle income countries (LMICs) remains limited. Methods and Results: Data from 153 cross-sectional Demographic and Health Surveys (DHS) across 61 LMICs conducted between 1990 and 2011 were combined to assess the association of birth timing with child stunting (height-for-age z-score

  13. Growth, spectral and crystallization perfection studies of semi organic non linear optical crystal - L-alanine lithium chloride

    Science.gov (United States)

    Redrothu, Hanumantharao; Kalainathan, S.; Bhagavannarayana, G.

    2012-06-01

    Single crystals of L-alanine lithium chloride single crystals were successfully grown using slow evaporation solution growth technique at constant temperature (303K). The formation of the new crystal has been confirmed by single-crystal X-ray diffraction, FT-IR studies. The crystalline perfection was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The powder second harmonic generation (SHG) has been confirmed by Nd: YAG laser. The results have been discussed in detail.

  14. Split photosystem protein, linear-mapping topology, and growth of structural complexity in the plastid genome of chromera velia

    KAUST Repository

    Janouškovec, Jan

    2013-08-22

    The canonical photosynthetic plastid genomes consist of a single circular-mapping chromosome that encodes a highly conserved protein core, involved in photosynthesis and ATP generation. Here, we demonstrate that the plastid genome of the photosynthetic relative of apicomplexans, Chromera velia, departs from this view in several unique ways. Core photosynthesis proteins PsaA and AtpB have been broken into two fragments, which we show are independently transcribed, oligoU-tailed, translated, and assembled into functional photosystem I and ATP synthase complexes. Genome-wide transcription profiles support expression of many other highly modified proteins, including several that contain extensions amounting to hundreds of amino acids in length. Canonical gene clusters and operons have been fragmented and reshuffled into novel putative transcriptional units. Massive genomic coverage by paired-end reads, coupled with pulsed-field gel electrophoresis and polymerase chain reaction, consistently indicate that the C. velia plastid genome is linear-mapping, a unique state among all plastids. Abundant intragenomic duplication probably mediated by recombination can explain protein splits, extensions, and genome linearization and is perhaps the key driving force behind the many features that defy the conventional ways of plastid genome architecture and function. © The Author 2013.

  15. Self-Esteem Trajectories among Ethnic Minority Adolescents: A Growth Curve Analysis of the Patterns and Predictors of Change

    Science.gov (United States)

    Greene, Melissa L.; Way, Niobe

    2005-01-01

    The current study presents a growth curve analysis of self-esteem among Black, Latino, and Asian American high school students. A series of hierarchical linear models were used to examine patterns and predictors of change in self-esteem over time. Results revealed an average increase in self-esteem with age. Although boys and girls experienced…

  16. Self-Esteem Trajectories among Ethnic Minority Adolescents: A Growth Curve Analysis of the Patterns and Predictors of Change

    Science.gov (United States)

    Greene, Melissa L.; Way, Niobe

    2005-01-01

    The current study presents a growth curve analysis of self-esteem among Black, Latino, and Asian American high school students. A series of hierarchical linear models were used to examine patterns and predictors of change in self-esteem over time. Results revealed an average increase in self-esteem with age. Although boys and girls experienced…

  17. Detecting Hierarchical Structure in Networks

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard;

    2012-01-01

    a generative Bayesian model that is able to infer whether hierarchies are present or not from a hypothesis space encompassing all types of hierarchical tree structures. For efficient inference we propose a collapsed Gibbs sampling procedure that jointly infers a partition and its hierarchical structure......Many real-world networks exhibit hierarchical organization. Previous models of hierarchies within relational data has focused on binary trees; however, for many networks it is unknown whether there is hierarchical structure, and if there is, a binary tree might not account well for it. We propose....... On synthetic and real data we demonstrate that our model can detect hierarchical structure leading to better link-prediction than competing models. Our model can be used to detect if a network exhibits hierarchical structure, thereby leading to a better comprehension and statistical account the network....

  18. Context updates are hierarchical

    Directory of Open Access Journals (Sweden)

    Anton Karl Ingason

    2016-10-01

    Full Text Available This squib studies the order in which elements are added to the shared context of interlocutors in a conversation. It focuses on context updates within one hierarchical structure and argues that structurally higher elements are entered into the context before lower elements, even if the structurally higher elements are pronounced after the lower elements. The crucial data are drawn from a comparison of relative clauses in two head-initial languages, English and Icelandic, and two head-final languages, Korean and Japanese. The findings have consequences for any theory of a dynamic semantics.

  19. GLOBAL EXISTENCE, UNIFORM DECAY AND EXPONENTIAL GROWTH FOR A CLASS OF SEMI-LINEAR WAVE EQUATION WITH STRONG DAMPING

    Institute of Scientific and Technical Information of China (English)

    Hua CHEN; Gongwei LIU

    2013-01-01

    In this paper,we consider the nonlinearly damped semi-linear wave equation associated with initial and Dirichlet boundary conditions.We prove the existence of a local weak solution and introduce a family of potential wells and discuss the invariants and vacuum isolating behavior of solutions.Furthermore,we prove the global existence of solutions in both cases which are polynomial and exponential decay in the energy space respectively,and the asymptotic behavior of solutions for the cases of potential well family with 0 < E(0) < d.At last we show that the energy will grow up as an exponential function as time goes to infinity,provided the initial data is large enough or E(0) < 0.

  20. Homoepitaxial Growth and Photoluminescence Properties of Hierarchical In2O3 Nanostuctures%分级氧化铟纳米结构的同质外延生长及发光性能

    Institute of Scientific and Technical Information of China (English)

    郭太波; 陈翌庆; 张新华; 刘利柱

    2011-01-01

    Large-scale hierarchical In2O3 nanostructures have been synthesized using vapor transport and condensation method without any catalyst, taking advantage of the self-assembly property and epitaxial vapor-solid (VS) growth mechanism, and were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show that the In2O3 nanorods are single crystals with body-centered cubic (bcc) structure, epitaxially growing along 〈100〉 and 〈111〉 directions. Homoepitaxial interconnections can be observed at the branched junctions, and the growth process of the nanorods arrayed on the microcrystals is a combination of “secondary nucleation” and VS process. The room-temperature photoluminescence spectrum of In2O3 nanostructures exhibited ultraviolet emission at 386 nm and blue emission at 435 nm, which can be ascribed to the near-band-edge (NBE) emission and the possible recombination of a photo-excited hole with an electron occupying the singly ionized oxygen vacancies, respectively.%用无催化碳热还原法合成了大量三维分级的In2O3亚微/纳米结构,用XRD、SEM、TEM和EDS等手段对In2O3纳米棒的形貌、成分和结构进行了表征.结果表明:In2O3纳米棒为具有体心立方结构单晶,沿着和方向外延生长,属于自组装和气固外延生长机制.同质外延生长的分级结构是"二次成核"和气固生长协同作用造成的.In2O3纳米棒的室温光致发光的发光峰位于386和435 nm,属于紫外发光和蓝光发光,分别起源于近带边发射和光生空穴与占据单离子氧空位的电子之间的复合.

  1. Associations of linear growth and relative weight gain during early life with adult health and human capital in countries of low and middle income: findings from five birth cohort studies

    OpenAIRE

    Adair, Linda S.; Fall, Caroline HD; Osmond, Clive; Aryeh D. Stein; Martorell, Reynaldo; Ramirez-Zea, Manuel; Sachdev, Harshpal Singh; Dahly, Darren L; Bas, Isabelita; Norris, Shane A; Micklesfield, Lisa; Hallal, Pedro; Victora, Cesar G.; ,

    2013-01-01

    Summary Background Fast weight gain and linear growth in children in low-income and middle-income countries are associated with enhanced survival and improved cognitive development, but might increase risk of obesity and related adult cardiometabolic diseases. We investigated how linear growth and relative weight gain during infancy and childhood are related to health and human capital outcomes in young adults. Methods We used data from five prospective birth cohort studies from Brazil, Guate...

  2. Determinants of linear growth from infancy to school-aged years: a population-based follow-up study in urban Amazonian children

    Directory of Open Access Journals (Sweden)

    Lourenço Barbara H

    2012-06-01

    Full Text Available Abstract Background Although linear growth during childhood may be affected by early-life exposures, few studies have examined whether the effects of these exposures linger on during school age, particularly in low- and middle-income countries. Methods We conducted a population-based longitudinal study of 256 children living in the Brazilian Amazon, aged 0.1 y to 5.5 y in 2003. Data regarding socioeconomic and maternal characteristics, infant feeding practices, morbidities, and birth weight and length were collected at baseline of the study (2003. Child body length/height was measured at baseline and at follow-up visits (in 2007 and 2009. Restricted cubic splines were used to construct average height-for-age Z score (HAZ growth curves, yielding estimated HAZ differences among exposure categories at ages 0.5 y, 1 y, 2 y, 5 y, 7 y, and 10 y. Results At baseline, median age was 2.6 y (interquartile range, 1.4 y–3.8 y, and mean HAZ was −0.53 (standard deviation, 1.15; 10.2% of children were stunted. In multivariable analysis, children in households above the household wealth index median were 0.30 Z taller at age 5 y (P = 0.017, and children whose families owned land were 0.34 Z taller by age 10 y (P = 0.023, when compared with poorer children. Mothers in the highest tertile for height had children whose HAZ were significantly higher compared with those of children from mothers in the lowest height tertile at all ages. Birth weight and length were positively related to linear growth throughout childhood; by age 10 y, children weighing >3500 g at birth were 0.31 Z taller than those weighing 2501 g to 3500 g (P = 0.022 at birth, and children measuring ≥51 cm at birth were 0.51 Z taller than those measuring ≤48 cm (P = 0.005. Conclusions Results suggest socioeconomic background is a potentially modifiable predictor of linear growth during the school-aged years. Maternal height and child’s anthropometric characteristics at

  3. First-passage phenomena in hierarchical networks

    CERN Document Server

    Tavani, Flavia

    2016-01-01

    In this paper we study Markov processes and related first passage problems on a class of weighted, modular graphs which generalize the Dyson hierarchical model. In these networks, the coupling strength between two nodes depends on their distance and is modulated by a parameter $\\sigma$. We find that, in the thermodynamic limit, ergodicity is lost and the "distant" nodes can not be reached. Moreover, for finite-sized systems, there exists a threshold value for $\\sigma$ such that, when $\\sigma$ is relatively large, the inhomogeneity of the coupling pattern prevails and "distant" nodes are hardly reached. The same analysis is carried on also for generic hierarchical graphs, where interactions are meant to involve $p$-plets ($p>2$) of nodes, finding that ergodicity is still broken in the thermodynamic limit, but no threshold value for $\\sigma$ is evidenced, ultimately due to a slow growth of the network diameter with the size.

  4. Efficient scalable algorithms for hierarchically semiseparable matrices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shen; Xia, Jianlin; Situ, Yingchong; Hoop, Maarten V. de

    2011-09-14

    Hierarchically semiseparable (HSS) matrix algorithms are emerging techniques in constructing the superfast direct solvers for both dense and sparse linear systems. Here, we develope a set of novel parallel algorithms for the key HSS operations that are used for solving large linear systems. These include the parallel rank-revealing QR factorization, the HSS constructions with hierarchical compression, the ULV HSS factorization, and the HSS solutions. The HSS tree based parallelism is fully exploited at the coarse level. The BLACS and ScaLAPACK libraries are used to facilitate the parallel dense kernel operations at the ne-grained level. We have appplied our new parallel HSS-embedded multifrontal solver to the anisotropic Helmholtz equations for seismic imaging, and were able to solve a linear system with 6.4 billion unknowns using 4096 processors, in about 20 minutes. The classical multifrontal solver simply failed due to high demand of memory. To our knowledge, this is the first successful demonstration of employing the HSS algorithms in solving the truly large-scale real-world problems. Our parallel strategies can be easily adapted to the parallelization of the other rank structured methods.

  5. Effects of animal source food and micronutrient fortification in complementary food products on body composition, iron status, and linear growth

    DEFF Research Database (Denmark)

    Skau, Jutta Kloppenborg Heick; Touch, Bunthang; Chhoun, Chamnan

    2015-01-01

    Background: Poor nutritional quality of complementary foods often limits growth. Animal source foods, such as milk or meat, are often unaffordable. Local affordable alternatives are needed. Objective: We evaluate the efficacy of 2 newly developed, rice-based complementary food products: WinFood (WF......) with small fish and edible spiders and WinFood-Lite (WF-L) fortified with small fish, against 2 existing fortified corn-soy blend products, CSB+ (purely plant based) and CSB++ (8% dried skimmed milk). Design: In total, 419 infants aged 6 mo were enrolled in this randomized, single-blinded study for 9 mo...... foods. The dietary role of edible spiders needs to be further explored. This trial was registered at controlled-trials.com as ISRCTN19918531....

  6. Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

    Energy Technology Data Exchange (ETDEWEB)

    Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604407, Tamil Nadu (India); Vinitha, G. [Department of Physics, School of Advanced Sciences, VIT Chennai, 600127 Tamil Nadu (India); Caroline, M. Lydia, E-mail: lydiacaroline2006@yahoo.co.in [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604407, Tamil Nadu (India)

    2017-04-15

    An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P2{sub 1}. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm{sup 2}. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics. - Graphical abstract: Good quality transparent single crystals of L-valinium L-valine chloride single crystal was grown by slow evaporation technique. The grown crystals were analyzed using different instrumentation methods to check its usefulness for the device fabrication. The determination of nonlinear refractive index (n{sub 2}), absorption coefficient (β) and third order nonlinear susceptibility was determined by Z scan technique, highlighted that LVVCl can serve as a promising candidate for opto electronic and nonlinear optical applications.

  7. Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

    Science.gov (United States)

    Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia

    2017-04-01

    An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

  8. Mechanics of hierarchical 3-D nanofoams

    Science.gov (United States)

    Chen, Q.; Pugno, N. M.

    2012-01-01

    In this paper, we study the mechanics of new three-dimensional hierarchical open-cell foams, and, in particular, its Young's modulus and plastic strength. We incorporate the effects of the surface elasticity and surface residual stress in the linear elastic and plastic analyses. The results show that, as the cross-sectional dimension decreases, the influences of the surface effect on Young's modulus and plastic strength increase, and the surface effect makes the solid stiffer and stronger; similarly, as level n increases, these quantities approach to those of the classical theory as lower bounds.

  9. Hierarchical Ag mesostructures for single particle SERS substrate

    Science.gov (United States)

    Xu, Minwei; Zhang, Yin

    2017-01-01

    Hierarchical Ag mesostructures with highly rough surface morphology have been synthesized at room temperature through a simple seed-mediated approach. Electron microscopy characterizations indicate that the obtained Ag mesostructures exhibit a textured surface morphology with the flower-like architecture. Moreover, the particle size can be tailored easily in the range of 250-500 nm. For the growth process of the hierarchical Ag mesostructures, it is believed that the self-assembly mechanism is more reasonable rather than the epitaxial overgrowth of Ag seed. The oriented attachment of nanoparticles is revealed during the formation of Ag mesostructures. Single particle surface enhanced Raman spectra (sp-SERS) of crystal violet adsorbed on the hierarchical Ag mesostructures were measured. Results reveal that the hierarchical Ag mesostructures can be highly sensitive sp-SERS substrates with good reproducibility. The average enhancement factors for individual Ag mesostructures are estimated to be about 106.

  10. Cellular and molecular insight into the inhibition of primary root growth of Arabidopsis induced by peptaibols, a class of linear peptide antibiotics mainly produced by Trichoderma spp.

    Science.gov (United States)

    Shi, Wei-Ling; Chen, Xiu-Lan; Wang, Li-Xia; Gong, Zhi-Ting; Li, Shuyu; Li, Chun-Long; Xie, Bin-Bin; Zhang, Wei; Shi, Mei; Li, Chuanyou; Zhang, Yu-Zhong; Song, Xiao-Yan

    2016-04-01

    Trichoderma spp. are well known biocontrol agents that produce a variety of antibiotics. Peptaibols are a class of linear peptide antibiotics mainly produced by Trichoderma Alamethicin, the most studied peptaibol, is reported as toxic to plants at certain concentrations, while the mechanisms involved are unclear. We illustrated the toxic mechanisms of peptaibols by studying the growth-inhibitory effect of Trichokonin VI (TK VI), a peptaibol from Trichoderma longibrachiatum SMF2, on Arabidopsis primary roots. TK VI inhibited root growth by suppressing cell division and cell elongation, and disrupting root stem cell niche maintenance. TK VI increased auxin content and disrupted auxin response gradients in root tips. Further, we screened the Arabidopsis TK VI-resistant mutant tkr1. tkr1 harbors a point mutation in GORK, which encodes gated outwardly rectifying K(+)channel proteins. This mutation alleviated TK VI-induced suppression of K(+)efflux in roots, thereby stabilizing the auxin gradient. The tkr1 mutant also resisted the phytotoxicity of alamethicin. Our results indicate that GORK channels play a key role in peptaibol-plant interaction and that there is an inter-relationship between GORK channels and maintenance of auxin homeostasis. The cellular and molecular insight into the peptaibol-induced inhibition of plant root growth advances our understanding of Trichoderma-plant interactions. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  11. A linear polyethylenimine mediated siRNA-based therapy targeting human epidermal growth factor receptor in SPC-A1 xenograft mice.

    Science.gov (United States)

    Zhang, Pinghai; Xu, Nuo; Zhou, Lei; Xu, Xin; Wang, Yuehong; Li, Ka; Zeng, Zhaochong; Wang, Xiangdong; Zhang, Xin; Bai, Chunxue

    2013-12-01

    Linear polyethylenimine (LPEI) is considered as a desirable gene in vivo delivery system, but whether it could deliver the specific siRNA targeted EGFR to the tumor site to inhibit the growth of NSCLC xenograft in nude mice still needs to be examined. In this study, LPEI/siRNA was made into a complex and SPC-A1-xenografted mice model was established. Then, stable LPEI/siRNA-EGFR complexes were intraperitoneally administrated. Afterwards, tumor growth was measured every 3 days. At the end of the experiment, tumor volume was calculated, and tumors were weighed, and examined for EGFR expression, proliferation, and apoptosis evaluations. By using blood samples, toxicity tests including aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine (Cr) were measured for liver and renal function evaluation. Serum concentrations of TNF-α and IFN-γ were also examined. Our results demonstrated that LPEI/siRNA-EGFR complexes could downregulate EGFR expression in SPC-A1 xenografted tumor upon single i.p. injection. LPEI/siRNA-EGFR complexes inhibited tumor growth and did not induce organ toxicity in SPC-A1-xenografted mice. At the end of the experiment no significant IFN-α increase was detected in LPEI/siRNA complexes or glucose-treated groups. The novel modality of siRNA-based therapy targeting EGFR may be of great potential in NSCLC treatment.

  12. Sensitivity analysis for linear structural equation models, longitudinal mediation with latent growth models and blended learning in biostatistics education

    Science.gov (United States)

    Sullivan, Adam John

    In chapter 1, we consider the biases that may arise when an unmeasured confounder is omitted from a structural equation model (SEM) and sensitivity analysis techniques to correct for such biases. We give an analysis of which effects in an SEM are and are not biased by an unmeasured confounder. It is shown that a single unmeasured confounder will bias not just one but numerous effects in an SEM. We present sensitivity analysis techniques to correct for biases in total, direct, and indirect effects when using SEM analyses, and illustrate these techniques with a study of aging and cognitive function. In chapter 2, we consider longitudinal mediation with latent growth curves. We define the direct and indirect effects using counterfactuals and consider the assumptions needed for identifiability of those effects. We develop models with a binary treatment/exposure followed by a model where treatment/exposure changes with time allowing for treatment/exposure-mediator interaction. We thus formalize mediation analysis with latent growth curve models using counterfactuals, makes clear the assumptions and extends these methods to allow for exposure mediator interactions. We present and illustrate the techniques with a study on Multiple Sclerosis(MS) and depression. In chapter 3, we report on a pilot study in blended learning that took place during the Fall 2013 and Summer 2014 semesters here at Harvard. We blended the traditional BIO 200: Principles of Biostatistics and created ID 200: Principles of Biostatistics and epidemiology. We used materials from the edX course PH207x: Health in Numbers: Quantitative Methods in Clinical & Public Health Research and used. These materials were used as a video textbook in which students would watch a given number of these videos prior to class. Using surveys as well as exam data we informally assess these blended classes from the student's perspective as well as a comparison of these students with students in another course, BIO 201

  13. Improving Measurement Precision of Hierarchical Latent Traits Using Adaptive Testing

    Science.gov (United States)

    Wang, Chun

    2014-01-01

    Many latent traits in social sciences display a hierarchical structure, such as intelligence, cognitive ability, or personality. Usually a second-order factor is linearly related to a group of first-order factors (also called domain abilities in cognitive ability measures), and the first-order factors directly govern the actual item responses.…

  14. Hierarchical Data Structures in Adventure Education and Therapy

    Science.gov (United States)

    Russell, Keith; Sibthorp, Jim

    2004-01-01

    Hierarchical linear modeling (HIM) is an approach used in data analysis to better understand how program outcomes are affected by the "nested" nature of data collected in many studies. An outcome can be considered variables such as an individual's self-efficacy, social skills, or more targeted outcomes such as demonstrated reading and mathematical…

  15. Hierarchical partial order ranking.

    Science.gov (United States)

    Carlsen, Lars

    2008-09-01

    Assessing the potential impact on environmental and human health from the production and use of chemicals or from polluted sites involves a multi-criteria evaluation scheme. A priori several parameters are to address, e.g., production tonnage, specific release scenarios, geographical and site-specific factors in addition to various substance dependent parameters. Further socio-economic factors may be taken into consideration. The number of parameters to be included may well appear to be prohibitive for developing a sensible model. The study introduces hierarchical partial order ranking (HPOR) that remedies this problem. By HPOR the original parameters are initially grouped based on their mutual connection and a set of meta-descriptors is derived representing the ranking corresponding to the single groups of descriptors, respectively. A second partial order ranking is carried out based on the meta-descriptors, the final ranking being disclosed though average ranks. An illustrative example on the prioritization of polluted sites is given.

  16. Trees and Hierarchical Structures

    CERN Document Server

    Haeseler, Arndt

    1990-01-01

    The "raison d'etre" of hierarchical dustering theory stems from one basic phe­ nomenon: This is the notorious non-transitivity of similarity relations. In spite of the fact that very often two objects may be quite similar to a third without being that similar to each other, one still wants to dassify objects according to their similarity. This should be achieved by grouping them into a hierarchy of non-overlapping dusters such that any two objects in ~ne duster appear to be more related to each other than they are to objects outside this duster. In everyday life, as well as in essentially every field of scientific investigation, there is an urge to reduce complexity by recognizing and establishing reasonable das­ sification schemes. Unfortunately, this is counterbalanced by the experience of seemingly unavoidable deadlocks caused by the existence of sequences of objects, each comparatively similar to the next, but the last rather different from the first.

  17. Hierarchical Affinity Propagation

    CERN Document Server

    Givoni, Inmar; Frey, Brendan J

    2012-01-01

    Affinity propagation is an exemplar-based clustering algorithm that finds a set of data-points that best exemplify the data, and associates each datapoint with one exemplar. We extend affinity propagation in a principled way to solve the hierarchical clustering problem, which arises in a variety of domains including biology, sensor networks and decision making in operational research. We derive an inference algorithm that operates by propagating information up and down the hierarchy, and is efficient despite the high-order potentials required for the graphical model formulation. We demonstrate that our method outperforms greedy techniques that cluster one layer at a time. We show that on an artificial dataset designed to mimic the HIV-strain mutation dynamics, our method outperforms related methods. For real HIV sequences, where the ground truth is not available, we show our method achieves better results, in terms of the underlying objective function, and show the results correspond meaningfully to geographi...

  18. Optimisation by hierarchical search

    Science.gov (United States)

    Zintchenko, Ilia; Hastings, Matthew; Troyer, Matthias

    2015-03-01

    Finding optimal values for a set of variables relative to a cost function gives rise to some of the hardest problems in physics, computer science and applied mathematics. Although often very simple in their formulation, these problems have a complex cost function landscape which prevents currently known algorithms from efficiently finding the global optimum. Countless techniques have been proposed to partially circumvent this problem, but an efficient method is yet to be found. We present a heuristic, general purpose approach to potentially improve the performance of conventional algorithms or special purpose hardware devices by optimising groups of variables in a hierarchical way. We apply this approach to problems in combinatorial optimisation, machine learning and other fields.

  19. How hierarchical is language use?

    Science.gov (United States)

    Frank, Stefan L.; Bod, Rens; Christiansen, Morten H.

    2012-01-01

    It is generally assumed that hierarchical phrase structure plays a central role in human language. However, considerations of simplicity and evolutionary continuity suggest that hierarchical structure should not be invoked too hastily. Indeed, recent neurophysiological, behavioural and computational studies show that sequential sentence structure has considerable explanatory power and that hierarchical processing is often not involved. In this paper, we review evidence from the recent literature supporting the hypothesis that sequential structure may be fundamental to the comprehension, production and acquisition of human language. Moreover, we provide a preliminary sketch outlining a non-hierarchical model of language use and discuss its implications and testable predictions. If linguistic phenomena can be explained by sequential rather than hierarchical structure, this will have considerable impact in a wide range of fields, such as linguistics, ethology, cognitive neuroscience, psychology and computer science. PMID:22977157

  20. How hierarchical is language use?

    Science.gov (United States)

    Frank, Stefan L; Bod, Rens; Christiansen, Morten H

    2012-11-22

    It is generally assumed that hierarchical phrase structure plays a central role in human language. However, considerations of simplicity and evolutionary continuity suggest that hierarchical structure should not be invoked too hastily. Indeed, recent neurophysiological, behavioural and computational studies show that sequential sentence structure has considerable explanatory power and that hierarchical processing is often not involved. In this paper, we review evidence from the recent literature supporting the hypothesis that sequential structure may be fundamental to the comprehension, production and acquisition of human language. Moreover, we provide a preliminary sketch outlining a non-hierarchical model of language use and discuss its implications and testable predictions. If linguistic phenomena can be explained by sequential rather than hierarchical structure, this will have considerable impact in a wide range of fields, such as linguistics, ethology, cognitive neuroscience, psychology and computer science.

  1. Inference in HIV dynamics models via hierarchical likelihood

    OpenAIRE

    2010-01-01

    HIV dynamical models are often based on non-linear systems of ordinary differential equations (ODE), which do not have analytical solution. Introducing random effects in such models leads to very challenging non-linear mixed-effects models. To avoid the numerical computation of multiple integrals involved in the likelihood, we propose a hierarchical likelihood (h-likelihood) approach, treated in the spirit of a penalized likelihood. We give the asymptotic distribution of the maximum h-likelih...

  2. Associative Hierarchical Random Fields.

    Science.gov (United States)

    Ladický, L'ubor; Russell, Chris; Kohli, Pushmeet; Torr, Philip H S

    2014-06-01

    This paper makes two contributions: the first is the proposal of a new model-The associative hierarchical random field (AHRF), and a novel algorithm for its optimization; the second is the application of this model to the problem of semantic segmentation. Most methods for semantic segmentation are formulated as a labeling problem for variables that might correspond to either pixels or segments such as super-pixels. It is well known that the generation of super pixel segmentations is not unique. This has motivated many researchers to use multiple super pixel segmentations for problems such as semantic segmentation or single view reconstruction. These super-pixels have not yet been combined in a principled manner, this is a difficult problem, as they may overlap, or be nested in such a way that the segmentations form a segmentation tree. Our new hierarchical random field model allows information from all of the multiple segmentations to contribute to a global energy. MAP inference in this model can be performed efficiently using powerful graph cut based move making algorithms. Our framework generalizes much of the previous work based on pixels or segments, and the resulting labelings can be viewed both as a detailed segmentation at the pixel level, or at the other extreme, as a segment selector that pieces together a solution like a jigsaw, selecting the best segments from different segmentations as pieces. We evaluate its performance on some of the most challenging data sets for object class segmentation, and show that this ability to perform inference using multiple overlapping segmentations leads to state-of-the-art results.

  3. SYNTHESIS OF HIERARCHICALLY POROUS ZEOLITE FAU/ALUMINA COMPOSITES BY SECONDARY GROWTH ON SEEDED ALUMINA SUBSTRATES%二次生长法合成多级孔道FAU/氧化铝复合物

    Institute of Scientific and Technical Information of China (English)

    王佳; 赵天波; 宗保宁; 杜泽学

    2016-01-01

    以整体型大孔-介孔氧化铝为载体,使用浸涂法负载NaY晶种并二次生长合成大孔-介孔-微孔FAU/氧化铝复合物,考察载体晶型及晶种胶的辅助作用对合成沸石复合物的影响;采用XRD、SEM、氮气吸附-脱附、DTA/TG对合成样品进行表征.结果表明:沸石在整体材料上的覆盖度由载体的物化性质、晶种悬浊液或二次晶化液的化学组成共同决定;γ-Al2O3载体经过含晶种胶的沸石悬浊液负载晶种,二次晶化后形成载体骨架部分转化为沸石且保持载体微观形貌的结构;α-Al2O3载体沸石的覆盖度因二次晶化液中晶种胶的辅助作用而明显改善.%The trimodal porous structured hierarchical FAU/alumina composites (macro-pores/meso-pores/micro-pores) were hydrothermally synthesized using macro-mesoporous alumina monoliths as substrates by seeding and secondary growth method.The influences of supports with different physicochemical features and the seed gel assistant on the properties of the resultant composites were studied.The zeolite seed and composites were characterized by XRD, SEM, nitrogen adsorption-desorption isotherms and DTA/TG.The results show that the coverage of zeolite on monoliths was determined by both of the physicochemical features of the substrates and the chemical compositions of the seed suspension or secondary crystallization solution.After being seeded, the substrate of γ-Al2O3 was partially transformed into zeolite structure with the retainment of the original substrate morphology.The zeolite coverage on α-Al2O3 support is improved significantly by the assistant of seed gel.

  4. Scaling-up access to family planning may improve linear growth and child development in low and middle income countries.

    Directory of Open Access Journals (Sweden)

    Günther Fink

    Full Text Available A large literature has indicated a robust association between birth spacing and child survival, but evidence on the association of birth timing with physical growth in low and middle income countries (LMICs remains limited.Data from 153 cross-sectional Demographic and Health Surveys (DHS across 61 LMICs conducted between 1990 and 2011 were combined to assess the association of birth timing with child stunting (height-for-age z-score <-2. A total of 623,789 children of birth order 1-5 contributed to the maternal age analysis, while the birth spacing dataset consisted of 584,226 children of birth order 2 and higher. Compared to 27-34 year old mothers, maternal age under 18 years was associated with a relative stunting risk of 1.35 (95% CI: 1.29-1.40 for firstborn children, whereas the relative risk was 1.24 (95% CI: 1.19-1.29 for mothers aged 18-19 years. The association of young maternal age with stunting was significantly greater for urban residents and those in the top 50% of household wealth. Birth intervals less than 12 months and 12-23 months had relative risks for stunting of 1.09 (95% CI: 1.06-1.12 and 1.06 (95% CI: 1.05-1.06 as compared to a 24-35 month inter-pregnancy interval, respectively. The strength of both teenage pregnancy and short birth interval associations showed substantial variation across WHO region. We estimate that 8.6% (6.9-10.3% of stunted cases in the South Asian DHS sample would have been averted by jointly eliminating teen pregnancies and birth intervals less than 24 months, while only 3.6% (1.5-5.7% of stunting cases would have prevented in the Middle East and North Africa sample.Postponing the age of first birth and increasing inter-pregnancy intervals has the potential to significantly reduce the prevalence of stunting and improve child development in LMICs.

  5. Construction and minimality of coordinated linear systems

    NARCIS (Netherlands)

    Kempker, P.L.; Ran, A.C.M.; Schuppen, J.H. van

    2014-01-01

    Coordinated linear systems are a particular class of hierarchical systems with a top-to-bottom information structure, consisting of a coordinator system and two or more subsystems. This paper deals with the construction and minimality of coordinated linear systems. Construction procedures are given

  6. Dietary diversity, animal source food consumption and linear growth among children aged 1-5 years in Bandung, Indonesia: a longitudinal observational study.

    Science.gov (United States)

    Muslimatun, Siti; Wiradnyani, Luh Ade Ari

    2016-07-01

    Dietary diversity involves adequate intake of macronutrient and micronutrient. The inclusion of animal source foods (ASF) in the diet helps prevent multiple nutrient deficiencies and any resultant, linear growth retardation. The objective of the current study was to assess the relationship between dietary diversity, ASF consumption and height-for-age z-score (HAZ) among children aged 12-59 months old across a 1-year observation. This longitudinal observational study without controls was conducted among four age groups: 12-23 months (n 57), 24-35 months (n 56), 36-47 months (n 58) and 48-59 months (n 56). Anthropometry and dietary intake were measured during each of four visits at 16-20-week intervals. The general characteristics and other observations were only collected at baseline and endline. During the year-long study period, approximately 27 % of the children ate a diverse diet (consumed ≥6 out of 9 food groups) according to ≥3 visits. ASF consumption was high, particularly for eggs, poultry, processed meats and liquid milk. Yet, micronutrient intake inadequacy, especially of Zn, Ca, Fe and vitamin A, was highly prevalent. A multivariate regression analysis showed that the consumption of a diverse diet and ASF was not significantly associated with the HAZ at endline, after controlling for demographic characteristics and the baseline HAZ. The consumption of a diverse diet was significantly associated with Ca intake adequacy. Moreover, ASF consumption was significantly associated with adequate intake of protein and micronutrients, particularly vitamin A, Ca and Zn. Thus, the recommendation is to continue and strengthen the promotion of consuming a diverse diet that includes ASF in supporting the linear growth of young children.

  7. Linearization Techniques

    Directory of Open Access Journals (Sweden)

    Gildeberto S. Cardoso

    2011-01-01

    Full Text Available This paper presents a study of linear control systems based on exact feedback linearization and approximate feedback linearization. As exact feedback linearization is applied, a linear controller can perform the control objectives. The approximate feedback linearization is required when a nonlinear system presents a noninvolutive property. It uses a Taylor series expansion in order to compute a nonlinear transformation of coordinates to satisfy the involutivity conditions.

  8. Patient satisfaction and organizational impact: a hierarchical linear modeling approach.

    Science.gov (United States)

    Otani, Koichiro; Kim, B Joon; Waterman, Brian; Boslaugh, Sarah; Klinkenberg, W Dean; Dunagan, W Claiborne

    2012-01-01

    This article presents the rationale for using multilevel analysis to address the broad environmental contexts in patient satisfaction research. This study utilized patient satisfaction data and the American Hospital Association Hospital Guide Book (2004). This study found significant contributions of individual patient attribute reactions (nursing care, physician care, etc.), and also clearly demonstrated hospital-level effects and cross-level interactions on patient satisfaction. Thus, it is clear that patient satisfaction is not solely explained by patients' attribute reactions and their demographic variables, but is also explained by patients' hospital levels. This approach would offer additional understanding in patient satisfaction research.

  9. Linear Logic Validation and Hierarchical Modeling for Interactive Storytelling Control

    OpenAIRE

    Dang, Kim Dung; Pham, Phuong Thao; Champagnat, Ronan; Rabah, Mourad

    2013-01-01

    International audience; The games are typical interactive applications where the system has to react to user actions and behavior with respect to some predefined rules established by the designer. The storytelling allows the interactive system to unfold the scenario of the game story according to these inputs and constraints. In order to improve system's behavior, the scenario should be structured and the system's control should be validated. In this paper, we deal with these two issues. We f...

  10. Hierarchical Dragonfly Wing: Microstructure-Biomechanical Behavior Relations

    Institute of Scientific and Technical Information of China (English)

    Yinglong Chen; Xishu Wang; Huaihui Ren; Hang Yin; Su Jia

    2012-01-01

    The dragonfly wing,which consists of veins and membrane,is of biological hierarchical material.We observed the cross-sections of longitudinal veins and membrane using Environmental Scanning Electron Microscopy (ESEM).Based on the experiments and previous studies,we described the longitudinal vein and the membrane in terms of two hierarchical levels of organization of composite materials at the micro- and nano-scales.The longitudinal vein of dragonfly wing has a complex sandwich structure with two chitinous shells and a protein layer,and it is considered as the first hierarchical level of the vein.Moreover,the chitinous shells are concentric multilayered structures.Clusters of nano-fibrils grow along the circumferential orientation embedded into the protein layer.It is considered as the second level of the hierarchy.Similarly,the upper and lower epidermises of membrane constitute the first hierarchical level of organization in micro scale.Similar to the vein shell,the membrane epidermises were found to be a paralleled multilayered structure,defined as the second hierarchical level of the membrane.Combining with the mechanical behavior analysis of the dragonfly wing,we concluded that the growth orientation of the hierarchical structure of the longitudinal vein and membrane is relevant to its biomechanical behavior.

  11. Hierarchical fringe tracking

    CERN Document Server

    Petrov, Romain G; Boskri, Abdelkarim; Folcher, Jean-Pierre; Lagarde, Stephane; Bresson, Yves; Benkhaldoum, Zouhair; Lazrek, Mohamed; Rakshit, Suvendu

    2014-01-01

    The limiting magnitude is a key issue for optical interferometry. Pairwise fringe trackers based on the integrated optics concepts used for example in GRAVITY seem limited to about K=10.5 with the 8m Unit Telescopes of the VLTI, and there is a general "common sense" statement that the efficiency of fringe tracking, and hence the sensitivity of optical interferometry, must decrease as the number of apertures increases, at least in the near infrared where we are still limited by detector readout noise. Here we present a Hierarchical Fringe Tracking (HFT) concept with sensitivity at least equal to this of a two apertures fringe trackers. HFT is based of the combination of the apertures in pairs, then in pairs of pairs then in pairs of groups. The key HFT module is a device that behaves like a spatial filter for two telescopes (2TSF) and transmits all or most of the flux of a cophased pair in a single mode beam. We give an example of such an achromatic 2TSF, based on very broadband dispersed fringes analyzed by g...

  12. Onboard hierarchical network

    Science.gov (United States)

    Tunesi, Luca; Armbruster, Philippe

    2004-02-01

    The objective of this paper is to demonstrate a suitable hierarchical networking solution to improve capabilities and performances of space systems, with significant recurrent costs saving and more efficient design & manufacturing flows. Classically, a satellite can be split in two functional sub-systems: the platform and the payload complement. The platform is in charge of providing power, attitude & orbit control and up/down-link services, whereas the payload represents the scientific and/or operational instruments/transponders and embodies the objectives of the mission. One major possibility to improve the performance of payloads, by limiting the data return to pertinent information, is to process data on board thanks to a proper implementation of the payload data system. In this way, it is possible to share non-recurring development costs by exploiting a system that can be adopted by the majority of space missions. It is believed that the Modular and Scalable Payload Data System, under development by ESA, provides a suitable solution to fulfil a large range of future mission requirements. The backbone of the system is the standardised high data rate SpaceWire network http://www.ecss.nl/. As complement, a lower speed command and control bus connecting peripherals is required. For instance, at instrument level, there is a need for a "local" low complexity bus, which gives the possibility to command and control sensors and actuators. Moreover, most of the connections at sub-system level are related to discrete signals management or simple telemetry acquisitions, which can easily and efficiently be handled by a local bus. An on-board hierarchical network can therefore be defined by interconnecting high-speed links and local buses. Additionally, it is worth stressing another important aspect of the design process: Agencies and ESA in particular are frequently confronted with a big consortium of geographically spread companies located in different countries, each one

  13. Hierarchical Reverberation Mapping

    CERN Document Server

    Brewer, Brendon J

    2013-01-01

    Reverberation mapping (RM) is an important technique in studies of active galactic nuclei (AGN). The key idea of RM is to measure the time lag $\\tau$ between variations in the continuum emission from the accretion disc and subsequent response of the broad line region (BLR). The measurement of $\\tau$ is typically used to estimate the physical size of the BLR and is combined with other measurements to estimate the black hole mass $M_{\\rm BH}$. A major difficulty with RM campaigns is the large amount of data needed to measure $\\tau$. Recently, Fine et al (2012) introduced a new approach to RM where the BLR light curve is sparsely sampled, but this is counteracted by observing a large sample of AGN, rather than a single system. The results are combined to infer properties of the sample of AGN. In this letter we implement this method using a hierarchical Bayesian model and contrast this with the results from the previous stacked cross-correlation technique. We find that our inferences are more precise and allow fo...

  14. Linear algebra

    CERN Document Server

    Shilov, Georgi E

    1977-01-01

    Covers determinants, linear spaces, systems of linear equations, linear functions of a vector argument, coordinate transformations, the canonical form of the matrix of a linear operator, bilinear and quadratic forms, Euclidean spaces, unitary spaces, quadratic forms in Euclidean and unitary spaces, finite-dimensional space. Problems with hints and answers.

  15. Linear Psoriasis

    Directory of Open Access Journals (Sweden)

    Agarwalla Arun

    2001-01-01

    Full Text Available Linear psoriasis, inflammatory linear varrucous epidermal naevus (ILVEN. Lichen straitus, linear lichen planus and invasion of epidermal naevi by psoriasis have clinical and histopathological overlap. We report two young male patients of true linear psoriasis without classical lesions elsewhere which were proved histopathologically. Seasonal variation and good response to topical antipsoriatic treatment supported the diagnosis.

  16. Hierarchical materials: Background and perspectives

    DEFF Research Database (Denmark)

    2016-01-01

    Hierarchical design draws inspiration from analysis of biological materials and has opened new possibilities for enhancing performance and enabling new functionalities and extraordinary properties. With the development of nanotechnology, the necessary technological requirements for the manufactur...

  17. Hierarchical clustering for graph visualization

    CERN Document Server

    Clémençon, Stéphan; Rossi, Fabrice; Tran, Viet Chi

    2012-01-01

    This paper describes a graph visualization methodology based on hierarchical maximal modularity clustering, with interactive and significant coarsening and refining possibilities. An application of this method to HIV epidemic analysis in Cuba is outlined.

  18. Direct hierarchical assembly of nanoparticles

    Science.gov (United States)

    Xu, Ting; Zhao, Yue; Thorkelsson, Kari

    2014-07-22

    The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

  19. Functional annotation of hierarchical modularity.

    Directory of Open Access Journals (Sweden)

    Kanchana Padmanabhan

    Full Text Available In biological networks of molecular interactions in a cell, network motifs that are biologically relevant are also functionally coherent, or form functional modules. These functionally coherent modules combine in a hierarchical manner into larger, less cohesive subsystems, thus revealing one of the essential design principles of system-level cellular organization and function-hierarchical modularity. Arguably, hierarchical modularity has not been explicitly taken into consideration by most, if not all, functional annotation systems. As a result, the existing methods would often fail to assign a statistically significant functional coherence score to biologically relevant molecular machines. We developed a methodology for hierarchical functional annotation. Given the hierarchical taxonomy of functional concepts (e.g., Gene Ontology and the association of individual genes or proteins with these concepts (e.g., GO terms, our method will assign a Hierarchical Modularity Score (HMS to each node in the hierarchy of functional modules; the HMS score and its p-value measure functional coherence of each module in the hierarchy. While existing methods annotate each module with a set of "enriched" functional terms in a bag of genes, our complementary method provides the hierarchical functional annotation of the modules and their hierarchically organized components. A hierarchical organization of functional modules often comes as a bi-product of cluster analysis of gene expression data or protein interaction data. Otherwise, our method will automatically build such a hierarchy by directly incorporating the functional taxonomy information into the hierarchy search process and by allowing multi-functional genes to be part of more than one component in the hierarchy. In addition, its underlying HMS scoring metric ensures that functional specificity of the terms across different levels of the hierarchical taxonomy is properly treated. We have evaluated our

  20. Hierarchical architecture of active knits

    Science.gov (United States)

    Abel, Julianna; Luntz, Jonathan; Brei, Diann

    2013-12-01

    Nature eloquently utilizes hierarchical structures to form the world around us. Applying the hierarchical architecture paradigm to smart materials can provide a basis for a new genre of actuators which produce complex actuation motions. One promising example of cellular architecture—active knits—provides complex three-dimensional distributed actuation motions with expanded operational performance through a hierarchically organized structure. The hierarchical structure arranges a single fiber of active material, such as shape memory alloys (SMAs), into a cellular network of interlacing adjacent loops according to a knitting grid. This paper defines a four-level hierarchical classification of knit structures: the basic knit loop, knit patterns, grid patterns, and restructured grids. Each level of the hierarchy provides increased architectural complexity, resulting in expanded kinematic actuation motions of active knits. The range of kinematic actuation motions are displayed through experimental examples of different SMA active knits. The results from this paper illustrate and classify the ways in which each level of the hierarchical knit architecture leverages the performance of the base smart material to generate unique actuation motions, providing necessary insight to best exploit this new actuation paradigm.

  1. A Bayesian hierarchical modeling approach for analyzing observational data from marine ecological studies.

    Science.gov (United States)

    Qian, Song S; Craig, J Kevin; Baustian, Melissa M; Rabalais, Nancy N

    2009-12-01

    We introduce the Bayesian hierarchical modeling approach for analyzing observational data from marine ecological studies using a data set intended for inference on the effects of bottom-water hypoxia on macrobenthic communities in the northern Gulf of Mexico off the coast of Louisiana, USA. We illustrate (1) the process of developing a model, (2) the use of the hierarchical model results for statistical inference through innovative graphical presentation, and (3) a comparison to the conventional linear modeling approach (ANOVA). Our results indicate that the Bayesian hierarchical approach is better able to detect a "treatment" effect than classical ANOVA while avoiding several arbitrary assumptions necessary for linear models, and is also more easily interpreted when presented graphically. These results suggest that the hierarchical modeling approach is a better alternative than conventional linear models and should be considered for the analysis of observational field data from marine systems.

  2. HIERARCHICAL OPTIMIZATION MODEL ON GEONETWORK

    Directory of Open Access Journals (Sweden)

    Z. Zha

    2012-07-01

    Full Text Available In existing construction experience of Spatial Data Infrastructure (SDI, GeoNetwork, as the geographical information integrated solution, is an effective way of building SDI. During GeoNetwork serving as an internet application, several shortcomings are exposed. The first one is that the time consuming of data loading has been considerately increasing with the growth of metadata count. Consequently, the efficiency of query and search service becomes lower. Another problem is that stability and robustness are both ruined since huge amount of metadata. The final flaw is that the requirements of multi-user concurrent accessing based on massive data are not effectively satisfied on the internet. A novel approach, Hierarchical Optimization Model (HOM, is presented to solve the incapability of GeoNetwork working with massive data in this paper. HOM optimizes the GeoNetwork from these aspects: internal procedure, external deployment strategies, etc. This model builds an efficient index for accessing huge metadata and supporting concurrent processes. In this way, the services based on GeoNetwork can maintain stable while running massive metadata. As an experiment, we deployed more than 30 GeoNetwork nodes, and harvest nearly 1.1 million metadata. From the contrast between the HOM-improved software and the original one, the model makes indexing and retrieval processes more quickly and keeps the speed stable on metadata amount increasing. It also shows stable on multi-user concurrent accessing to system services, the experiment achieved good results and proved that our optimization model is efficient and reliable.

  3. Hierarchical Bayesian sparse image reconstruction with application to MRFM

    CERN Document Server

    Dobigeon, Nicolas; Tourneret, Jean-Yves

    2008-01-01

    This paper presents a hierarchical Bayesian model to reconstruct sparse images when the observations are obtained from linear transformations and corrupted by an additive white Gaussian noise. Our hierarchical Bayes model is well suited to such naturally sparse image applications as it seamlessly accounts for properties such as sparsity and positivity of the image via appropriate Bayes priors. We propose a prior that is based on a weighted mixture of a positive exponential distribution and a mass at zero. The prior has hyperparameters that are tuned automatically by marginalization over the hierarchical Bayesian model. To overcome the complexity of the posterior distribution, a Gibbs sampling strategy is proposed. The Gibbs samples can be used to estimate the image to be recovered, e.g. by maximizing the estimated posterior distribution. In our fully Bayesian approach the posteriors of all the parameters are available. Thus our algorithm provides more information than other previously proposed sparse reconstr...

  4. Advanced hierarchical distance sampling

    Science.gov (United States)

    Royle, Andy

    2016-01-01

    In this chapter, we cover a number of important extensions of the basic hierarchical distance-sampling (HDS) framework from Chapter 8. First, we discuss the inclusion of “individual covariates,” such as group size, in the HDS model. This is important in many surveys where animals form natural groups that are the primary observation unit, with the size of the group expected to have some influence on detectability. We also discuss HDS integrated with time-removal and double-observer or capture-recapture sampling. These “combined protocols” can be formulated as HDS models with individual covariates, and thus they have a commonality with HDS models involving group structure (group size being just another individual covariate). We cover several varieties of open-population HDS models that accommodate population dynamics. On one end of the spectrum, we cover models that allow replicate distance sampling surveys within a year, which estimate abundance relative to availability and temporary emigration through time. We consider a robust design version of that model. We then consider models with explicit dynamics based on the Dail and Madsen (2011) model and the work of Sollmann et al. (2015). The final major theme of this chapter is relatively newly developed spatial distance sampling models that accommodate explicit models describing the spatial distribution of individuals known as Point Process models. We provide novel formulations of spatial DS and HDS models in this chapter, including implementations of those models in the unmarked package using a hack of the pcount function for N-mixture models.

  5. Multiple comparisons in genetic association studies: a hierarchical modeling approach.

    Science.gov (United States)

    Yi, Nengjun; Xu, Shizhong; Lou, Xiang-Yang; Mallick, Himel

    2014-02-01

    Multiple comparisons or multiple testing has been viewed as a thorny issue in genetic association studies aiming to detect disease-associated genetic variants from a large number of genotyped variants. We alleviate the problem of multiple comparisons by proposing a hierarchical modeling approach that is fundamentally different from the existing methods. The proposed hierarchical models simultaneously fit as many variables as possible and shrink unimportant effects towards zero. Thus, the hierarchical models yield more efficient estimates of parameters than the traditional methods that analyze genetic variants separately, and also coherently address the multiple comparisons problem due to largely reducing the effective number of genetic effects and the number of statistically "significant" effects. We develop a method for computing the effective number of genetic effects in hierarchical generalized linear models, and propose a new adjustment for multiple comparisons, the hierarchical Bonferroni correction, based on the effective number of genetic effects. Our approach not only increases the power to detect disease-associated variants but also controls the Type I error. We illustrate and evaluate our method with real and simulated data sets from genetic association studies. The method has been implemented in our freely available R package BhGLM (http://www.ssg.uab.edu/bhglm/).

  6. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Science.gov (United States)

    Saito, Noriko; Haneda, Hajime

    2011-12-01

    We review the solvothermal synthesis, using a mixture of ethylene glycol (EG) and water as the solvent, of zinc oxide (ZnO) particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i) EG restricts the growth of ZnO microcrystals, (ii) EG promotes the self-assembly of small crystallites into spheroidal particles and (iii) the high water content of EG results in hollow spheres.

  7. Hierarchical structures of ZnO spherical particles synthesized solvothermally

    Directory of Open Access Journals (Sweden)

    Noriko Saito and Hajime Haneda

    2011-01-01

    Full Text Available We review the solvothermal synthesis, using a mixture of ethylene glycol (EG and water as the solvent, of zinc oxide (ZnO particles having spherical and flower-like shapes and hierarchical nanostructures. The preparation conditions of the ZnO particles and the microscopic characterization of the morphology are summarized. We found the following three effects of the ratio of EG to water on the formation of hierarchical structures: (i EG restricts the growth of ZnO microcrystals, (ii EG promotes the self-assembly of small crystallites into spheroidal particles and (iii the high water content of EG results in hollow spheres.

  8. Hierarchical topic modeling with nested hierarchical Dirichlet process

    Institute of Scientific and Technical Information of China (English)

    Yi-qun DING; Shan-ping LI; Zhen ZHANG; Bin SHEN

    2009-01-01

    This paper deals with the statistical modeling of latent topic hierarchies in text corpora. The height of the topic tree is assumed as fixed, while the number of topics on each level as unknown a priori and to be inferred from data. Taking a nonparametric Bayesian approach to this problem, we propose a new probabilistic generative model based on the nested hierarchical Dirichlet process (nHDP) and present a Markov chain Monte Carlo sampling algorithm for the inference of the topic tree structure as welt as the word distribution of each topic and topic distribution of each document. Our theoretical analysis and experiment results show that this model can produce a more compact hierarchical topic structure and captures more free-grained topic relationships compared to the hierarchical latent Dirichlet allocation model.

  9. Fabrication and analysis of gecko-inspired hierarchical polymer nanosetae.

    Science.gov (United States)

    Ho, Audrey Yoke Yee; Yeo, Lip Pin; Lam, Yee Cheong; Rodríguez, Isabel

    2011-03-22

    A gecko's superb ability to adhere to surfaces is widely credited to the large attachment area of the hierarchical and fibrillar structure on its feet. The combination of these two features provides the necessary compliance for the gecko toe-pad to effectively engage a high percentage of the spatulae at each step to any kind of surface topography. With the use of multi-tiered porous anodic alumina template and capillary force assisted nanoimprinting, we have successfully fabricated a gecko-inspired hierarchical topography of branched nanopillars on a stiff polymer. We also demonstrated that the hierarchical topography improved the shear adhesion force over a topography of linear structures by 150%. A systematic analysis to understand the phenomenon was performed. It was determined that the effective stiffness of the hierarchical branched structure was lower than that of the linear structure. The reduction in effective stiffness favored a more efficient bending of the branched topography and a better compliance to a test surface, hence resulting in a higher area of residual deformation. As the area of residual deformation increased, the shear adhesion force emulated. The branched pillar topography also showed a marked increase in hydrophobicity, which is an essential property in the practical applications of these structures for good self-cleaning in dry adhesion conditions.

  10. Modelling hierarchical and modular complex networks: division and independence

    Science.gov (United States)

    Kim, D.-H.; Rodgers, G. J.; Kahng, B.; Kim, D.

    2005-06-01

    We introduce a growing network model which generates both modular and hierarchical structure in a self-organized way. To this end, we modify the Barabási-Albert model into the one evolving under the principles of division and independence as well as growth and preferential attachment (PA). A newly added vertex chooses one of the modules composed of existing vertices, and attaches edges to vertices belonging to that module following the PA rule. When the module size reaches a proper size, the module is divided into two, and a new module is created. The karate club network studied by Zachary is a simple version of the current model. We find that the model can reproduce both modular and hierarchical properties, characterized by the hierarchical clustering function of a vertex with degree k, C(k), being in good agreement with empirical measurements for real-world networks.

  11. Renormalization of Hierarchically Interacting Isotropic Diffusions

    Science.gov (United States)

    den Hollander, F.; Swart, J. M.

    1998-10-01

    We study a renormalization transformation arising in an infinite system of interacting diffusions. The components of the system are labeled by the N-dimensional hierarchical lattice ( N≥2) and take values in the closure of a compact convex set bar D subset {R}^d (d ≥slant 1). Each component starts at some θ ∈ D and is subject to two motions: (1) an isotropic diffusion according to a local diffusion rate g: bar D to [0,infty ] chosen from an appropriate class; (2) a linear drift toward an average of the surrounding components weighted according to their hierarchical distance. In the local mean-field limit N→∞, block averages of diffusions within a hierarchical distance k, on an appropriate time scale, are expected to perform a diffusion with local diffusion rate F ( k) g, where F^{(k)} g = (F_{c_k } circ ... circ F_{c_1 } ) g is the kth iterate of renormalization transformations F c ( c>0) applied to g. Here the c k measure the strength of the interaction at hierarchical distance k. We identify F c and study its orbit ( F ( k) g) k≥0. We show that there exists a "fixed shape" g* such that lim k→∞ σk F ( k) g = g* for all g, where the σ k are normalizing constants. In terms of the infinite system, this property means that there is complete universal behavior on large space-time scales. Our results extend earlier work for d = 1 and bar D = [0,1], resp. [0, ∞). The renormalization transformation F c is defined in terms of the ergodic measure of a d-dimensional diffusion. In d = 1 this diffusion allows a Yamada-Watanabe-type coupling, its ergodic measure is reversible, and the renormalization transformation F c is given by an explicit formula. All this breaks down in d≥2, which complicates the analysis considerably and forces us to new methods. Part of our results depend on a certain martingale problem being well-posed.

  12. Deliberate change without hierarchical influence?

    DEFF Research Database (Denmark)

    Nørskov, Sladjana; Kesting, Peter; Ulhøi, John Parm

    2017-01-01

    Purpose This paper aims to present that deliberate change is strongly associated with formal structures and top-down influence. Hierarchical configurations have been used to structure processes, overcome resistance and get things done. But is deliberate change also possible without formal...... reveals that deliberate change is indeed achievable in a non-hierarchical collaborative OSS community context. However, it presupposes the presence and active involvement of informal change agents. The paper identifies and specifies four key drivers for change agents’ influence. Originality....../value The findings contribute to organisational analysis by providing a deeper understanding of the importance of leadership in making deliberate change possible in non-hierarchical settings. It points to the importance of “change-by-conviction”, essentially based on voluntary behaviour. This can open the door...

  13. Static Correctness of Hierarchical Procedures

    DEFF Research Database (Denmark)

    Schwartzbach, Michael Ignatieff

    1990-01-01

    A system of hierarchical, fully recursive types in a truly imperative language allows program fragments written for small types to be reused for all larger types. To exploit this property to enable type-safe hierarchical procedures, it is necessary to impose a static requirement on procedure calls....... We introduce an example language and prove the existence of a sound requirement which preserves static correctness while allowing hierarchical procedures. This requirement is further shown to be optimal, in the sense that it imposes as few restrictions as possible. This establishes the theoretical...... basis for a general type hierarchy with static type checking, which enables first-order polymorphism combined with multiple inheritance and specialization in a language with assignments. We extend the results to include opaque types. An opaque version of a type is different from the original but has...

  14. Linear Text vs. Non-Linear Hypertext in Handheld Computers: Effects on Declarative and Structural Knowledge, and Learner Motivation

    Science.gov (United States)

    Son, Chanhee; Park, Sanghoon; Kim, Minjeong

    2011-01-01

    This study compared linear text-based and non-linear hypertext-based instruction in a handheld computer regarding effects on two different levels of knowledge (declarative and structural knowledge) and learner motivation. Forty four participants were randomly assigned to one of three experimental conditions: linear text, hierarchical hypertext,…

  15. The structure of dust aggregates in hierarchical coagulation

    CERN Document Server

    Dominik, Carsten; Borel, Herman

    2016-01-01

    Dust coagulation in interstellar space and protoplanetary disks is usually treated as one of 2 extreme cases: Particle-Cluster Aggregation and Cluster-Cluster Aggregation. In this paper we study the process of hierarchical growth, where aggregates are built from significantly smaller aggregates (but not monomers). We show that this process can be understood as a modified, PCA-like process that produces porous, but non-fractal particles whose filling factor is chiefly determined by the porosity of the building blocks. We also show that in a coagulation environment where relative velocities are driven by turbulence, a logarithmically flat mass distribution (equal mass per mass decade) as it is typically found in environments where fragmentation replenishes small grains, leads to a situation where small particles and aggregates dominate the growth of large ones. Therefore, in such environments, hierarchical growth should be seen as the norm. Consequently, we predict that the aggregates in such environments are n...

  16. Structural integrity of hierarchical composites

    Directory of Open Access Journals (Sweden)

    Marco Paggi

    2012-01-01

    Full Text Available Interface mechanical problems are of paramount importance in engineering and materials science. Traditionally, due to the complexity of modelling their mechanical behaviour, interfaces are often treated as defects and their features are not explored. In this study, a different approach is illustrated, where the interfaces play an active role in the design of innovative hierarchical composites and are fundamental for their structural integrity. Numerical examples regarding cutting tools made of hierarchical cellular polycrystalline materials are proposed, showing that tailoring of interface properties at the different scales is the way to achieve superior mechanical responses that cannot be obtained using standard materials

  17. Non-hierarchical clustering methods on factorial subspaces

    OpenAIRE

    Tortora, Cristina

    2011-01-01

    Cluster analysis (CA) aims at finding homogeneous group of individuals, where homogeneous is referred to individuals that present similar characteristics. Many CA techniques already exist, among the non-hierarchical ones the most known, thank to its simplicity and computational property, is k-means method. However, the method is unstable when the number of variables is large and when variables are correlated. This problem leads to the development of two-step methods, they perform a linear tra...

  18. Distinguishing between linear and exponential cell growth during the division cycle: Single-cell studies, cell-culture studies, and the object of cell-cycle research

    OpenAIRE

    Cooper Stephen

    2006-01-01

    Abstract Background Two approaches to understanding growth during the cell cycle are single-cell studies, where growth during the cell cycle of a single cell is measured, and cell-culture studies, where growth during the cell cycle of a large number of cells as an aggregate is analyzed. Mitchison has proposed that single-cell studies, because they show variations in cell growth patterns, are more suitable for understanding cell growth during the cell cycle, and should be preferred over cultur...

  19. Effect of complementary feeding with lipid-based nutrient supplements and corn-soy blend on the incidence of stunting and linear growth among 6- to 18-month-old infants and children in rural Malawi.

    Science.gov (United States)

    Mangani, Charles; Maleta, Kenneth; Phuka, John; Cheung, Yin Bun; Thakwalakwa, Chrissie; Dewey, Kathryn; Manary, Mark; Puumalainen, Taneli; Ashorn, Per

    2015-12-01

    Low nutritional value of complementary foods is associated with high incidence of childhood growth stunting in low-income countries. This study was done to test a hypothesis that dietary complementation with lipid-based nutrient supplements (LNS) promotes linear growth and reduces the incidence of severe stunting among at-risk infants. A total of 840 6-month-old healthy infants in rural Malawi were enrolled to a randomised assessor-blinded trial. The participants received 12-month supplementation with nothing, milk-LNS, soy-LNS, or corn-soy blend (CSB). Supplements provided micronutrients and approximately 280 kcal energy per day. Outcomes were incidence of severe and very severe stunting [length-for-age z-score, (LAZ) supplementation and the lower incidence of stunting. Exploratory analyses suggest that provision of milk-LNS, but not soy-LNS promotes linear growth among at-risk infants mainly between 9 and 12 months of age.

  20. A Review on the Fabrication of Hierarchical ZnO Nanostructures for Photocatalysis Application

    Directory of Open Access Journals (Sweden)

    Yi Xia

    2016-11-01

    Full Text Available Semiconductor photocatalysis provides potential solutions for many energy and environmental-related issues. Recently, various semiconductors with hierarchical nanostructures have been fabricated to achieve efficient photocatalysts owing to their multiple advantages, such as high surface area, porous structures, as well as enhanced light harvesting. ZnO has been widely investigated and considered as the most promising alternative photocatalyst to TiO2. Herein, we present a review on the fabrication methods, growth mechanisms and photocatalytic applications of hierarchical ZnO nanostructures. Various synthetic strategies and growth mechanisms, including multistep sequential growth routes, template-based synthesis, template-free self-organization and precursor or self-templating strategies, are highlighted. In addition, the fabrication of multicomponent ZnO-based nanocomposites with hierarchical structures is also included. Finally, the application of hierarchical ZnO nanostructures and nanocomposites in typical photocatalytic reactions, such as pollutant degradation and H2 evolution, is reviewed.

  1. Cellular interactions on hierarchical poly(ε-caprolactone) nanowire micropatterns.

    Science.gov (United States)

    Du, Ke; Gan, Zhihua

    2012-09-26

    A double template method to fabricate poly(ε-caprolactone) (PCL) hierarchical patterned nanowires with highly ordered nano- and microscaled topography was developed in this study. The topography of PCL film with a patterned nanowire surface can be easily and well controlled by changing the template and melting time of PCL film on the templates. The surface morphology, water contact angle, protein adsorption, and cell growth behavior on the PCL films with different surface structures were well studied. The results revealed that the PCL nanowire arrays and the hierarchical patterned nanowires showed higher capability of protein adsorption and better cell growth than the PCL film with smooth surface. Typically, the PCL surface with hierarchical nanowire patterns was most favorable for cell attachment and proliferation. The present study was innovative at fabrication of polymer substrates with hierarchical architecture of nanowires inside microscaled islands to gain insight into the cell response to this unique topography and to develop a new method of constructing the bionic surface for tissue engineering applications.

  2. Sensory Hierarchical Organization and Reading.

    Science.gov (United States)

    Skapof, Jerome

    The purpose of this study was to judge the viability of an operational approach aimed at assessing response styles in reading using the hypothesis of sensory hierarchical organization. A sample of 103 middle-class children from a New York City public school, between the ages of five and seven, took part in a three phase experiment. Phase one…

  3. A Hierarchical Algorithm for Integrated Scheduling and Control With Applications to Power Systems

    DEFF Research Database (Denmark)

    Sokoler, Leo Emil; Dinesen, Peter Juhler; Jørgensen, John Bagterp

    2016-01-01

    The contribution of this paper is a hierarchical algorithm for integrated scheduling and control via model predictive control of hybrid systems. The controlled system is a linear system composed of continuous control, state, and output variables. Binary variables occur as scheduling decisions...... portfolio case study show that the hierarchical algorithm reduces the computation to solve the OCP by several orders of magnitude. The improvement in computation time is achieved without a significant increase in the overall cost of operation....

  4. Hierarchical modeling and its numerical implementation for layered thin elastic structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jin-Rae [Hongik University, Sejong (Korea, Republic of)

    2017-05-15

    Thin elastic structures such as beam- and plate-like structures and laminates are characterized by the small thickness, which lead to classical plate and laminate theories in which the displacement fields through the thickness are assumed linear or higher-order polynomials. These classical theories are either insufficient to represent the complex stress variation through the thickness or may encounter the accuracy-computational cost dilemma. In order to overcome the inherent problem of classical theories, the concept of hierarchical modeling has been emerged. In the hierarchical modeling, the hierarchical models with different model levels are selected and combined within a structure domain, in order to make the modeling error be distributed as uniformly as possible throughout the problem domain. The purpose of current study is to explore the potential of hierarchical modeling for the effective numerical analysis of layered structures such as laminated composite. For this goal, the hierarchical models are constructed and the hierarchical modeling is implemented by selectively adjusting the level of hierarchical models. As well, the major characteristics of hierarchical models are investigated through the numerical experiments.

  5. Crack Propagation in Bamboo's Hierarchical Cellular Structure

    Science.gov (United States)

    Habibi, Meisam K.; Lu, Yang

    2014-07-01

    Bamboo, as a natural hierarchical cellular material, exhibits remarkable mechanical properties including excellent flexibility and fracture toughness. As far as bamboo as a functionally graded bio-composite is concerned, the interactions of different constituents (bamboo fibers; parenchyma cells; and vessels.) alongside their corresponding interfacial areas with a developed crack should be of high significance. Here, by using multi-scale mechanical characterizations coupled with advanced environmental electron microscopy (ESEM), we unambiguously show that fibers' interfacial areas along with parenchyma cells' boundaries were preferred routes for crack growth in both radial and longitudinal directions. Irrespective of the honeycomb structure of fibers along with cellular configuration of parenchyma ground, the hollow vessels within bamboo culm affected the crack propagation too, by crack deflection or crack-tip energy dissipation. It is expected that the tortuous crack propagation mode exhibited in the present study could be applicable to other cellular natural materials as well.

  6. Linear Systems.

    Science.gov (United States)

    The report documents a series of seminars at Rome Air Development Center with the content equivalent to an intense course in Linear Systems . Material...is slanted toward the practicing engineer and introduces some of the fundamental concepts and techniques for analyzing linear systems . Techniques for

  7. Linear response theory for quantum open systems

    OpenAIRE

    Wei, J. H.; Yan, YiJing

    2011-01-01

    Basing on the theory of Feynman's influence functional and its hierarchical equations of motion, we develop a linear response theory for quantum open systems. Our theory provides an effective way to calculate dynamical observables of a quantum open system at its steady-state, which can be applied to various fields of non-equilibrium condensed matter physics.

  8. Amino acids assisted hydrothermal synthesis of hierarchically structured ZnO with enhanced photocatalytic activities

    Science.gov (United States)

    Guo, Yanxia; Lin, Siwen; Li, Xuan; Liu, Yuping

    2016-10-01

    Novel hierarchically structured ZnO, including rose-like, dandelion-like and flower-like, have been synthesized through a simple hydrothermal process using different amino acids (glutamine, histidine and glycine) as structure-directing agents and urea as deposition agent, followed by subsequent calcination. Amino acids played a crucial role in the formation of hierarchically structured ZnO, and different amino acids could induce different exquisite shapes and assembly ways, as well as more oxygen defects. The prepared hierarchically structured ZnO exhibited excellent photocatalytic activities for the photodegradation of Rhodamine B, which was associated with their special hierarchical structures, large BET surface area and the existence of more oxygen defects. Amino acid-assisted growth mechanism of hierarchically structured ZnO was also discussed.

  9. Hierarchical Prisoner's Dilemma in Hierarchical Public-Goods Game

    CERN Document Server

    Fujimoto, Yuma; Kaneko, Kunihiko

    2016-01-01

    The dilemma in cooperation is one of the major concerns in game theory. In a public-goods game, each individual pays a cost for cooperation, or to prevent defection, and receives a reward from the collected cost in a group. Thus, defection is beneficial for each individual, while cooperation is beneficial for the group. Now, groups (say, countries) consisting of individual players also play games. To study such a multi-level game, we introduce a hierarchical public-goods (HPG) game in which two groups compete for finite resources by utilizing costs collected from individuals in each group. Analyzing this HPG game, we found a hierarchical prisoner's dilemma, in which groups choose the defection policy (say, armaments) as a Nash strategy to optimize each group's benefit, while cooperation optimizes the total benefit. On the other hand, for each individual within a group, refusing to pay the cost (say, tax) is a Nash strategy, which turns to be a cooperation policy for the group, thus leading to a hierarchical d...

  10. Linear algebra

    CERN Document Server

    Stoll, R R

    1968-01-01

    Linear Algebra is intended to be used as a text for a one-semester course in linear algebra at the undergraduate level. The treatment of the subject will be both useful to students of mathematics and those interested primarily in applications of the theory. The major prerequisite for mastering the material is the readiness of the student to reason abstractly. Specifically, this calls for an understanding of the fact that axioms are assumptions and that theorems are logical consequences of one or more axioms. Familiarity with calculus and linear differential equations is required for understand

  11. On the rotational intergrowth of hierarchical FAU/EMT zeolites.

    Science.gov (United States)

    Khaleel, Maryam; Wagner, Andrew J; Mkhoyan, K Andre; Tsapatsis, Michael

    2014-09-01

    A structural study of a hierarchical zeolite X, which is similar to the one first synthesized by Inayat et al.,12 was performed using transmission electron microscopy imaging and diffraction. Evidence is provided, by comparison to simulations, that this material is an intergrowth of FAU and EMT and a conceptual model is presented for the growth of the FAU material with a small fraction of EMT in an atypical morphology of assembled sheets with well-defined intersection angles.

  12. Linear Models

    CERN Document Server

    Searle, Shayle R

    2012-01-01

    This 1971 classic on linear models is once again available--as a Wiley Classics Library Edition. It features material that can be understood by any statistician who understands matrix algebra and basic statistical methods.

  13. Linear programming

    CERN Document Server

    Solow, Daniel

    2014-01-01

    This text covers the basic theory and computation for a first course in linear programming, including substantial material on mathematical proof techniques and sophisticated computation methods. Includes Appendix on using Excel. 1984 edition.

  14. Linear algebra

    CERN Document Server

    Berberian, Sterling K

    2014-01-01

    Introductory treatment covers basic theory of vector spaces and linear maps - dimension, determinants, eigenvalues, and eigenvectors - plus more advanced topics such as the study of canonical forms for matrices. 1992 edition.

  15. Linear algebra

    CERN Document Server

    Liesen, Jörg

    2015-01-01

    This self-contained textbook takes a matrix-oriented approach to linear algebra and presents a complete theory, including all details and proofs, culminating in the Jordan canonical form and its proof. Throughout the development, the applicability of the results is highlighted. Additionally, the book presents special topics from applied linear algebra including matrix functions, the singular value decomposition, the Kronecker product and linear matrix equations. The matrix-oriented approach to linear algebra leads to a better intuition and a deeper understanding of the abstract concepts, and therefore simplifies their use in real world applications. Some of these applications are presented in detailed examples. In several ‘MATLAB-Minutes’ students can comprehend the concepts and results using computational experiments. Necessary basics for the use of MATLAB are presented in a short introduction. Students can also actively work with the material and practice their mathematical skills in more than 300 exerc...

  16. 进城务工人员随迁子女的学业成就及其影响因素——基于多层次线性模型(HLM)的分析%The Empirical Study on The Academic Achievement of Children of Migrant Workers And Its Inlfuencing Factors:Basing on analysis of Hierarchical Linear Model(HLM)

    Institute of Scientific and Technical Information of China (English)

    尚伟伟

    2015-01-01

    This study investigate the student's academic performance of 3800 children of migrant workers form Henan province Zhengzhou, Luoyang, Xuchang city, and then adopt the method of Hierarchical Linear Modeling(HLM), explores the impact of different level factors of the individuals, families and schools for children's academic achievement of migrant workers. The results showed that: the migrant children schools and public schools there were signiifcant differences in students' academic achievement, the academic achievement differences are 6.13% between schools; From inside the public schools, the academic achievement exist obvious differences in the group between the children of migrant workers and local children; Peer relations, parents' education expectation and expectation by themselves have a signiifcantly positive inlfuence on students' academic achievement, frequency of transfering and lfowing, the way to school time on students' academic achievement is a signiifcant negative impact; The level of teachers' wages have signiifcant positive inlfuence on students' academic achievement, but the training number of teachers have negative inlfuence on students' academic achievement.%本研究对河南省郑州、洛阳、许昌三所城市的3714名进城务工人员随迁子女进行了学生学业成就调查,然后采用多层线性模型分析的方法,探索了学生个体、家庭、学校不同层面因素对进城务工人员随迁子女学业成就产生的影响.研究结果显示:民工子弟学校与公立学校在学生学业成就方面存在显著的差异,其中有6.13%的学业成就差异来源于校际之间;在公立学校内部,进城务工人员随迁子女与本地户籍学生的学业成就存在明显的组内差异;同伴关系、父母教育期望以及学生自我期望对学生学业成就均有显著的正向影响,转学流动频率、上学路上花费时间对学生学业成就则有显著的负向影响;教师工资水平对学生学业

  17. Hierarchical structure of biological systems

    Science.gov (United States)

    Alcocer-Cuarón, Carlos; Rivera, Ana L; Castaño, Victor M

    2014-01-01

    A general theory of biological systems, based on few fundamental propositions, allows a generalization of both Wierner and Berthalanffy approaches to theoretical biology. Here, a biological system is defined as a set of self-organized, differentiated elements that interact pair-wise through various networks and media, isolated from other sets by boundaries. Their relation to other systems can be described as a closed loop in a steady-state, which leads to a hierarchical structure and functioning of the biological system. Our thermodynamical approach of hierarchical character can be applied to biological systems of varying sizes through some general principles, based on the exchange of energy information and/or mass from and within the systems. PMID:24145961

  18. Automatic Hierarchical Color Image Classification

    Directory of Open Access Journals (Sweden)

    Jing Huang

    2003-02-01

    Full Text Available Organizing images into semantic categories can be extremely useful for content-based image retrieval and image annotation. Grouping images into semantic classes is a difficult problem, however. Image classification attempts to solve this hard problem by using low-level image features. In this paper, we propose a method for hierarchical classification of images via supervised learning. This scheme relies on using a good low-level feature and subsequently performing feature-space reconfiguration using singular value decomposition to reduce noise and dimensionality. We use the training data to obtain a hierarchical classification tree that can be used to categorize new images. Our experimental results suggest that this scheme not only performs better than standard nearest-neighbor techniques, but also has both storage and computational advantages.

  19. Intuitionistic fuzzy hierarchical clustering algorithms

    Institute of Scientific and Technical Information of China (English)

    Xu Zeshui

    2009-01-01

    Intuitionistic fuzzy set (IFS) is a set of 2-tuple arguments, each of which is characterized by a mem-bership degree and a nonmembership degree. The generalized form of IFS is interval-valued intuitionistic fuzzy set (IVIFS), whose components are intervals rather than exact numbers. IFSs and IVIFSs have been found to be very useful to describe vagueness and uncertainty. However, it seems that little attention has been focused on the clus-tering analysis of IFSs and IVIFSs. An intuitionistic fuzzy hierarchical algorithm is introduced for clustering IFSs, which is based on the traditional hierarchical clustering procedure, the intuitionistic fuzzy aggregation operator, and the basic distance measures between IFSs: the Hamming distance, normalized Hamming, weighted Hamming, the Euclidean distance, the normalized Euclidean distance, and the weighted Euclidean distance. Subsequently, the algorithm is extended for clustering IVIFSs. Finally the algorithm and its extended form are applied to the classifications of building materials and enterprises respectively.

  20. Hierarchical Formation of Galactic Clusters

    CERN Document Server

    Elmegreen, B G

    2006-01-01

    Young stellar groupings and clusters have hierarchical patterns ranging from flocculent spiral arms and star complexes on the largest scale to OB associations, OB subgroups, small loose groups, clusters and cluster subclumps on the smallest scales. There is no obvious transition in morphology at the cluster boundary, suggesting that clusters are only the inner parts of the hierarchy where stars have had enough time to mix. The power-law cluster mass function follows from this hierarchical structure: n(M_cl) M_cl^-b for b~2. This value of b is independently required by the observation that the summed IMFs from many clusters in a galaxy equals approximately the IMF of each cluster.

  1. Hierarchical Cont-Bouchaud model

    CERN Document Server

    Paluch, Robert; Holyst, Janusz A

    2015-01-01

    We extend the well-known Cont-Bouchaud model to include a hierarchical topology of agent's interactions. The influence of hierarchy on system dynamics is investigated by two models. The first one is based on a multi-level, nested Erdos-Renyi random graph and individual decisions by agents according to Potts dynamics. This approach does not lead to a broad return distribution outside a parameter regime close to the original Cont-Bouchaud model. In the second model we introduce a limited hierarchical Erdos-Renyi graph, where merging of clusters at a level h+1 involves only clusters that have merged at the previous level h and we use the original Cont-Bouchaud agent dynamics on resulting clusters. The second model leads to a heavy-tail distribution of cluster sizes and relative price changes in a wide range of connection densities, not only close to the percolation threshold.

  2. Template-Free Fabrication of Bi2WO6 Hierarchical Hollow Microspheres with Visible-Light-Driven Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yuxue Zhou

    2016-09-01

    Full Text Available Highly hierarchical hollow bismuth tungstate (Bi2WO6 microspheres self-assembled by thin nanoplates have been fabricated via a facile template-free solvothermal route. The possible growth pattern and formation mechanism of hierarchical hollow Bi2WO6 microspheres was investigated. The excellent visible-light-driven photocatalytic performance on rhodamine B (RhB degradation was displayed by hierarchical hollow Bi2WO6 microspheres. Such well-organized hierarchical hollow Bi2WO6 microspheres show potential application in water treatment fields by full use of solar energy.

  3. Hybrid and hierarchical composite materials

    CERN Document Server

    Kim, Chang-Soo; Sano, Tomoko

    2015-01-01

    This book addresses a broad spectrum of areas in both hybrid materials and hierarchical composites, including recent development of processing technologies, structural designs, modern computer simulation techniques, and the relationships between the processing-structure-property-performance. Each topic is introduced at length with numerous  and detailed examples and over 150 illustrations.   In addition, the authors present a method of categorizing these materials, so that representative examples of all material classes are discussed.

  4. Treatment Protocols as Hierarchical Structures

    Science.gov (United States)

    Ben-Bassat, Moshe; Carlson, Richard W.; Puri, Vinod K.; Weil, Max Harry

    1978-01-01

    We view a treatment protocol as a hierarchical structure of therapeutic modules. The lowest level of this structure consists of individual therapeutic actions. Combinations of individual actions define higher level modules, which we call routines. Routines are designed to manage limited clinical problems, such as the routine for fluid loading to correct hypovolemia. Combinations of routines and additional actions, together with comments, questions, or precautions organized in a branching logic, in turn, define the treatment protocol for a given disorder. Adoption of this modular approach may facilitate the formulation of treatment protocols, since the physician is not required to prepare complex flowcharts. This hierarchical approach also allows protocols to be updated and modified in a flexible manner. By use of such a standard format, individual components may be fitted together to create protocols for multiple disorders. The technique is suited for computer implementation. We believe that this hierarchical approach may facilitate standarization of patient care as well as aid in clinical teaching. A protocol for acute pancreatitis is used to illustrate this technique.

  5. Hierarchical method of task assignment for multiple cooperating UAV teams

    Institute of Scientific and Technical Information of China (English)

    Xiaoxuan Hu; Huawei Ma; Qingsong Ye; He Luo

    2015-01-01

    The problem of task assignment for multiple cooperat-ing unmanned aerial vehicle (UAV) teams is considered. Multiple UAVs forming several smal teams are needed to perform attack tasks on a set of predetermined ground targets. A hierarchical task assignment method is presented to address the problem. It breaks the original problem down to three levels of sub-problems: tar-get clustering, cluster al ocation and target assignment. The first two sub-problems are central y solved by using clustering algo-rithms and integer linear programming, respectively, and the third sub-problem is solved in a distributed and paral el manner, using a mixed integer linear programming model and an improved ant colony algorithm. The proposed hierarchical method can reduce the computational complexity of the task assignment problem con-siderably, especial y when the number of tasks or the number of UAVs is large. Experimental results show that this method is feasi-ble and more efficient than non-hierarchical methods.

  6. Lidov-Kozai Mechanism in Hydrodynamical Disks: Linear Stability Analysis

    Science.gov (United States)

    Zanazzi, J. J.; Lai, Dong

    2017-01-01

    Recent SPH simulations by Martin et al. (2014) suggest a circumstellar gaseous disk may exhibit coherent eccentricity-inclination oscillations due to the tidal forcing of an inclined binary companion, in a manner that resembles Lidov-Kozai oscillations in hierarchical triple systems. We carry out linear stability analysis for the eccentricity growth of circumstellar disks in binaries, including the effects of gas pressure and viscosity and secular (orbital-averaged) tidal force from the inclined companion. We find that the growth of disk eccentricity depends on the dimensionless ratio (S) between c_s^2 (the disk sound speed squared) and the tidal torque acting on the disk (per unit mass) from the companion. For S ≪ 1, the standard Lidov-Kozai result is recovered for a thin disk annulus: eccentricity excitation occurs when the mutual inclination I between the disk and binary lies between 39° and 141°. As S increases, the inclination window for eccentricity growth generally becomes narrower. For S ≳ a few, eccentricity growth is suppressed for all inclination angles. Surprisingly, we find that for S ˜ 1 and certain disk density/pressure profiles, eccentricity excitation can occur even when I is much less than 39°.

  7. Understanding the unusual adsorption behavior in hierarchical zeolite nanosheets.

    Science.gov (United States)

    Bai, Peng; Olson, David H; Tsapatsis, Michael; Siepmann, J Ilja

    2014-08-04

    Hierarchical zeolites are advanced materials possessing the catalytic and adsorption properties of conventional zeolites while eliminating their transport limitations through the introduction of mesopores. Recent experiments comparing the adsorption in hierarchical self-pillared pentasils (SPP) and silicalite-1 (MFI) revealed an interesting crossover in sorbate loading for branched or long-chain alkanes but not for shorter linear alkanes, but an explanation for this behavior is not readily available through experimental probes due to the complications arising from the presence of multiple adsorption sites. Here we present a molecular simulation study on the adsorption of alkane isomers and show that a multi-step mechanism, found here for all molecules, is responsible for the observed phenomena. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Linear regression

    CERN Document Server

    Olive, David J

    2017-01-01

    This text covers both multiple linear regression and some experimental design models. The text uses the response plot to visualize the model and to detect outliers, does not assume that the error distribution has a known parametric distribution, develops prediction intervals that work when the error distribution is unknown, suggests bootstrap hypothesis tests that may be useful for inference after variable selection, and develops prediction regions and large sample theory for the multivariate linear regression model that has m response variables. A relationship between multivariate prediction regions and confidence regions provides a simple way to bootstrap confidence regions. These confidence regions often provide a practical method for testing hypotheses. There is also a chapter on generalized linear models and generalized additive models. There are many R functions to produce response and residual plots, to simulate prediction intervals and hypothesis tests, to detect outliers, and to choose response trans...

  9. Linear algebra

    CERN Document Server

    Sahai, Vivek

    2013-01-01

    Beginning with the basic concepts of vector spaces such as linear independence, basis and dimension, quotient space, linear transformation and duality with an exposition of the theory of linear operators on a finite dimensional vector space, this book includes the concept of eigenvalues and eigenvectors, diagonalization, triangulation and Jordan and rational canonical forms. Inner product spaces which cover finite dimensional spectral theory and an elementary theory of bilinear forms are also discussed. This new edition of the book incorporates the rich feedback of its readers. We have added new subject matter in the text to make the book more comprehensive. Many new examples have been discussed to illustrate the text. More exercises have been included. We have taken care to arrange the exercises in increasing order of difficulty. There is now a new section of hints for almost all exercises, except those which are straightforward, to enhance their importance for individual study and for classroom use.

  10. Linear algebra

    CERN Document Server

    Edwards, Harold M

    1995-01-01

    In his new undergraduate textbook, Harold M Edwards proposes a radically new and thoroughly algorithmic approach to linear algebra Originally inspired by the constructive philosophy of mathematics championed in the 19th century by Leopold Kronecker, the approach is well suited to students in the computer-dominated late 20th century Each proof is an algorithm described in English that can be translated into the computer language the class is using and put to work solving problems and generating new examples, making the study of linear algebra a truly interactive experience Designed for a one-semester course, this text adopts an algorithmic approach to linear algebra giving the student many examples to work through and copious exercises to test their skills and extend their knowledge of the subject Students at all levels will find much interactive instruction in this text while teachers will find stimulating examples and methods of approach to the subject

  11. Clinical time series prediction: Toward a hierarchical dynamical system framework.

    Science.gov (United States)

    Liu, Zitao; Hauskrecht, Milos

    2015-09-01

    Developing machine learning and data mining algorithms for building temporal models of clinical time series is important for understanding of the patient condition, the dynamics of a disease, effect of various patient management interventions and clinical decision making. In this work, we propose and develop a novel hierarchical framework for modeling clinical time series data of varied length and with irregularly sampled observations. Our hierarchical dynamical system framework for modeling clinical time series combines advantages of the two temporal modeling approaches: the linear dynamical system and the Gaussian process. We model the irregularly sampled clinical time series by using multiple Gaussian process sequences in the lower level of our hierarchical framework and capture the transitions between Gaussian processes by utilizing the linear dynamical system. The experiments are conducted on the complete blood count (CBC) panel data of 1000 post-surgical cardiac patients during their hospitalization. Our framework is evaluated and compared to multiple baseline approaches in terms of the mean absolute prediction error and the absolute percentage error. We tested our framework by first learning the time series model from data for the patients in the training set, and then using it to predict future time series values for the patients in the test set. We show that our model outperforms multiple existing models in terms of its predictive accuracy. Our method achieved a 3.13% average prediction accuracy improvement on ten CBC lab time series when it was compared against the best performing baseline. A 5.25% average accuracy improvement was observed when only short-term predictions were considered. A new hierarchical dynamical system framework that lets us model irregularly sampled time series data is a promising new direction for modeling clinical time series and for improving their predictive performance. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Learning curve estimation in medical devices and procedures: hierarchical modeling.

    Science.gov (United States)

    Govindarajulu, Usha S; Stillo, Marco; Goldfarb, David; Matheny, Michael E; Resnic, Frederic S

    2017-07-30

    In the use of medical device procedures, learning effects have been shown to be a critical component of medical device safety surveillance. To support their estimation of these effects, we evaluated multiple methods for modeling these rates within a complex simulated dataset representing patients treated by physicians clustered within institutions. We employed unique modeling for the learning curves to incorporate the learning hierarchy between institution and physicians and then modeled them within established methods that work with hierarchical data such as generalized estimating equations (GEE) and generalized linear mixed effect models. We found that both methods performed well, but that the GEE may have some advantages over the generalized linear mixed effect models for ease of modeling and a substantially lower rate of model convergence failures. We then focused more on using GEE and performed a separate simulation to vary the shape of the learning curve as well as employed various smoothing methods to the plots. We concluded that while both hierarchical methods can be used with our mathematical modeling of the learning curve, the GEE tended to perform better across multiple simulated scenarios in order to accurately model the learning effect as a function of physician and hospital hierarchical data in the use of a novel medical device. We found that the choice of shape used to produce the 'learning-free' dataset would be dataset specific, while the choice of smoothing method was negligibly different from one another. This was an important application to understand how best to fit this unique learning curve function for hierarchical physician and hospital data. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Clinical time series prediction: towards a hierarchical dynamical system framework

    Science.gov (United States)

    Liu, Zitao; Hauskrecht, Milos

    2014-01-01

    Objective Developing machine learning and data mining algorithms for building temporal models of clinical time series is important for understanding of the patient condition, the dynamics of a disease, effect of various patient management interventions and clinical decision making. In this work, we propose and develop a novel hierarchical framework for modeling clinical time series data of varied length and with irregularly sampled observations. Materials and methods Our hierarchical dynamical system framework for modeling clinical time series combines advantages of the two temporal modeling approaches: the linear dynamical system and the Gaussian process. We model the irregularly sampled clinical time series by using multiple Gaussian process sequences in the lower level of our hierarchical framework and capture the transitions between Gaussian processes by utilizing the linear dynamical system. The experiments are conducted on the complete blood count (CBC) panel data of 1000 post-surgical cardiac patients during their hospitalization. Our framework is evaluated and compared to multiple baseline approaches in terms of the mean absolute prediction error and the absolute percentage error. Results We tested our framework by first learning the time series model from data for the patient in the training set, and then applying the model in order to predict future time series values on the patients in the test set. We show that our model outperforms multiple existing models in terms of its predictive accuracy. Our method achieved a 3.13% average prediction accuracy improvement on ten CBC lab time series when it was compared against the best performing baseline. A 5.25% average accuracy improvement was observed when only short-term predictions were considered. Conclusion A new hierarchical dynamical system framework that lets us model irregularly sampled time series data is a promising new direction for modeling clinical time series and for improving their predictive

  14. Linear algebra

    CERN Document Server

    Allenby, Reg

    1995-01-01

    As the basis of equations (and therefore problem-solving), linear algebra is the most widely taught sub-division of pure mathematics. Dr Allenby has used his experience of teaching linear algebra to write a lively book on the subject that includes historical information about the founders of the subject as well as giving a basic introduction to the mathematics undergraduate. The whole text has been written in a connected way with ideas introduced as they occur naturally. As with the other books in the series, there are many worked examples.Solutions to the exercises are available onlin

  15. Hierarchical spatiotemporal matrix models for characterizing invasions.

    Science.gov (United States)

    Hooten, Mevin B; Wikle, Christopher K; Dorazio, Robert M; Royle, J Andrew

    2007-06-01

    The growth and dispersal of biotic organisms is an important subject in ecology. Ecologists are able to accurately describe survival and fecundity in plant and animal populations and have developed quantitative approaches to study the dynamics of dispersal and population size. Of particular interest are the dynamics of invasive species. Such nonindigenous animals and plants can levy significant impacts on native biotic communities. Effective models for relative abundance have been developed; however, a better understanding of the dynamics of actual population size (as opposed to relative abundance) in an invasion would be beneficial to all branches of ecology. In this article, we adopt a hierarchical Bayesian framework for modeling the invasion of such species while addressing the discrete nature of the data and uncertainty associated with the probability of detection. The nonlinear dynamics between discrete time points are intuitively modeled through an embedded deterministic population model with density-dependent growth and dispersal components. Additionally, we illustrate the importance of accommodating spatially varying dispersal rates. The method is applied to the specific case of the Eurasian Collared-Dove, an invasive species at mid-invasion in the United States at the time of this writing.

  16. Hierarchical flexural strength of enamel: transition from brittle to damage-tolerant behaviour.

    Science.gov (United States)

    Bechtle, Sabine; Özcoban, Hüseyin; Lilleodden, Erica T; Huber, Norbert; Schreyer, Andreas; Swain, Michael V; Schneider, Gerold A

    2012-06-07

    Hard, biological materials are generally hierarchically structured from the nano- to the macro-scale in a somewhat self-similar manner consisting of mineral units surrounded by a soft protein shell. Considerable efforts are underway to mimic such materials because of their structurally optimized mechanical functionality of being hard and stiff as well as damage-tolerant. However, it is unclear how different hierarchical levels interact to achieve this performance. In this study, we consider dental enamel as a representative, biological hierarchical structure and determine its flexural strength and elastic modulus at three levels of hierarchy using focused ion beam (FIB) prepared cantilevers of micrometre size. The results are compared and analysed using a theoretical model proposed by Jäger and Fratzl and developed by Gao and co-workers. Both properties decrease with increasing hierarchical dimension along with a switch in mechanical behaviour from linear-elastic to elastic-inelastic. We found Gao's model matched the results very well.

  17. Comment on the paper: "Crystal growth and spectroscopic characterization of Aloevera amino acid added lithium sulfate monohydrate: a non-linear optical crystal".

    Science.gov (United States)

    Srinivasan, Bikshandarkoil R

    2015-01-05

    The title paper (Manimekalai et al., 2014) reports a slow evaporation solution growth of a so called 'Aloevera amino acid added lithium sulfate monohydrate' (AALSMH) crystal. In this communication, many points of criticism, concerning the crystal growth, NMR spectrum and X-ray powder pattern of this so called AALSMH nonlinear optical crystal are highlighted. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Growth and characterization of binary and pseudo-binary 3-5 compounds exhibiting non-linear optical behavior. Undergraduate research opportunities in microgravity science and technology

    Science.gov (United States)

    Witt, August F.

    1992-01-01

    In line with the specified objectives, a Bridgman-type growth configuration in which unavoidable end effects - conventionally leading to growth interface relocation - are compensated by commensurate input-power changes is developed; the growth rate on a microscale is predictable and unaffected by changes in heat transfer conditions. To permit quantitative characterization of the growth furnace cavity (hot-zone), a 3-D thermal field mapping technique, based on the thermal image, is being tested for temperatures up to 1100 C. Computational NIR absorption analysis was modified to now permit characterization of semi-insulating single crystals. Work on growth and characterization of bismuth-silicate was initiated. Growth of BSO (B12SiO20) for seed material by the Czochralski technique is currently in progress. Undergraduate research currently in progress includes: ground based measurements of the wetting behavior (contact angles) of semiconductor melts on substrates consisting of potential confinement materials for solidification experiments in a reduced gravity environment. Hardware modifications required for execution of the wetting experiments in a KC-135 facility are developed.

  19. Hierarchical Control for Smart Grids

    DEFF Research Database (Denmark)

    Trangbæk, K; Bendtsen, Jan Dimon; Stoustrup, Jakob

    2011-01-01

    This paper deals with hierarchical model predictive control (MPC) of smart grid systems. The design consists of a high level MPC controller, a second level of so-called aggregators, which reduces the computational and communication-related load on the high-level control, and a lower level...... of autonomous consumers. The control system is tasked with balancing electric power production and consumption within the smart grid, and makes active use of the flexibility of a large number of power producing and/or power consuming units. The objective is to accommodate the load variation on the grid, arising...

  20. Scalable Hierarchical Algorithms for stochastic PDEs and UQ

    KAUST Repository

    Litvinenko, Alexander

    2015-01-07

    H-matrices and Fast Multipole (FMM) are powerful methods to approximate linear operators coming from partial differential and integral equations as well as speed up computational cost from quadratic or cubic to log-linear (O(n log n)), where n number of degrees of freedom in the discretization. The storage is reduced to the log-linear as well. This hierarchical structure is a good starting point for parallel algorithms. Parallelization on shared and distributed memory systems was pioneered by Kriemann [1,2]. Since 2005, the area of parallel architectures and software is developing very fast. Progress in GPUs and Many-Core Systems (e.g. XeonPhi with 64 cores) motivated us to extend work started in [1,2,7,8].

  1. Scalable Hierarchical Algorithms for stochastic PDEs and Uncertainty Quantification

    KAUST Repository

    Litvinenko, Alexander

    2015-01-05

    H-matrices and Fast Multipole (FMM) are powerful methods to approximate linear operators coming from partial differential and integral equations as well as speed up computational cost from quadratic or cubic to log-linear (O(n log n)), where n number of degrees of freedom in the discretization. The storage is reduced to the log-linear as well. This hierarchical structure is a good starting point for parallel algorithms. Parallelization on shared and distributed memory systems was pioneered by R. Kriemann, 2005. Since 2005, the area of parallel architectures and software is developing very fast. Progress in GPUs and Many-Core Systems (e.g. XeonPhi with 64 cores) motivated us to extend work started in [1,2,7,8].

  2. Hierarchical Structures in Hypertext Learning Environments

    NARCIS (Netherlands)

    Bezdan, Eniko; Kester, Liesbeth; Kirschner, Paul A.

    2011-01-01

    Bezdan, E., Kester, L., & Kirschner, P. A. (2011, 9 September). Hierarchical Structures in Hypertext Learning Environments. Presentation for the visit of KU Leuven, Open University, Heerlen, The Netherlands.

  3. Linear programming

    CERN Document Server

    Karloff, Howard

    1991-01-01

    To this reviewer’s knowledge, this is the first book accessible to the upper division undergraduate or beginning graduate student that surveys linear programming from the Simplex Method…via the Ellipsoid algorithm to Karmarkar’s algorithm. Moreover, its point of view is algorithmic and thus it provides both a history and a case history of work in complexity theory. The presentation is admirable; Karloff's style is informal (even humorous at times) without sacrificing anything necessary for understanding. Diagrams (including horizontal brackets that group terms) aid in providing clarity. The end-of-chapter notes are helpful...Recommended highly for acquisition, since it is not only a textbook, but can also be used for independent reading and study. —Choice Reviews The reader will be well served by reading the monograph from cover to cover. The author succeeds in providing a concise, readable, understandable introduction to modern linear programming. —Mathematics of Computing This is a textbook intend...

  4. Simulating Self-organization and Interference between Certain Hierarchical Structures.

    Science.gov (United States)

    Raczynski, Stanislaw

    2014-10-01

    A model of the dynamics and interactions between organizations with self-organizing hierarchical structures is presented for discrete events. The active objects of the model are individuals (people, organization members). The parameters of an individual are ability, corruption level, resources, and lust for power, among others. Three organizations are generated and interact with each other, attempting to gain more members and power. The individuals appear and disappear, due to a simple 'birth-and-death' process. If an individual disappears from the model, a corresponding reconfiguration in the hierarchical structure occurs. The organization's growth and macro-patterns are the result of the activities of the individuals. The aim of the simulation is to visualize the evolution of the organizations and the stability of the whole system. A 'steady state' for the model is rare; instead, in most parameter configurations, the model enters into oscillations.

  5. Hierarchical Modelling of Flood Risk for Engineering Decision Analysis

    DEFF Research Database (Denmark)

    Custer, Rocco

    Societies around the world are faced with flood risk, prompting authorities and decision makers to manage risk to protect population and assets. With climate change, urbanisation and population growth, flood risk changes constantly, requiring flood risk management strategies that are flexible...... and robust. Traditional risk management solutions, e.g. dike construction, are not particularly flexible, as they are difficult to adapt to changing risk. Conversely, the recent concept of integrated flood risk management, entailing a combination of several structural and non-structural risk management...... measures, allows identifying flexible and robust flood risk management strategies. Based on it, this thesis investigates hierarchical flood protection systems, which encompass two, or more, hierarchically integrated flood protection structures on different spatial scales (e.g. dikes, local flood barriers...

  6. Dynamic Organization of Hierarchical Memories.

    Science.gov (United States)

    Kurikawa, Tomoki; Kaneko, Kunihiko

    2016-01-01

    In the brain, external objects are categorized in a hierarchical way. Although it is widely accepted that objects are represented as static attractors in neural state space, this view does not take account interaction between intrinsic neural dynamics and external input, which is essential to understand how neural system responds to inputs. Indeed, structured spontaneous neural activity without external inputs is known to exist, and its relationship with evoked activities is discussed. Then, how categorical representation is embedded into the spontaneous and evoked activities has to be uncovered. To address this question, we studied bifurcation process with increasing input after hierarchically clustered associative memories are learned. We found a "dynamic categorization"; neural activity without input wanders globally over the state space including all memories. Then with the increase of input strength, diffuse representation of higher category exhibits transitions to focused ones specific to each object. The hierarchy of memories is embedded in the transition probability from one memory to another during the spontaneous dynamics. With increased input strength, neural activity wanders over a narrower state space including a smaller set of memories, showing more specific category or memory corresponding to the applied input. Moreover, such coarse-to-fine transitions are also observed temporally during transient process under constant input, which agrees with experimental findings in the temporal cortex. These results suggest the hierarchy emerging through interaction with an external input underlies hierarchy during transient process, as well as in the spontaneous activity.

  7. Combined treatment with GH and IGF-I: additive effect on cortical bone mass but not on linear bone growth in female rats.

    Science.gov (United States)

    Sundström, Katja; Cedervall, Therese; Ohlsson, Claes; Camacho-Hübner, Cecilia; Sävendahl, Lars

    2014-12-01

    The growth-promoting effect of combined therapy with GH and IGF-I in normal rats is not known. We therefore investigated the efficacy of treatment with recombinant human (rh)GH and/or rhIGF-I on longitudinal bone growth and bone mass in intact, prepubertal, female Sprague-Dawley rats. rhGH was injected twice daily sc (5 mg/kg·d) and rhIGF-I continuously infused sc (2.2 or 4.4 mg/kg·d) for 28 days. Longitudinal bone growth was monitored by weekly x-rays of tibiae and nose-anus length measurements, and tibial growth plate histomorphology was analyzed. Bone mass was evaluated by peripheral quantitative computed tomography. In addition, serum levels of IGF-I, rat GH, acid labile subunit, IGF binding protein-3, 150-kDa ternary complex formation, and markers of bone formation and degradation were measured. Monotherapy with rhGH was more effective than rhIGF-I (4.4 mg/kg·d) to increase tibia and nose-anus length, whereas combined therapy did not further increase tibia, or nose-anus, lengths or growth plate height. In contrast, combined rhGH and rhIGF-I (4.4 mg/kg·d) therapy had an additive stimulatory effect on cortical bone mass vs rhGH alone. Combined treatment with rhGH and rhIGF-I resulted in markedly higher serum IGF-I concentrations vs rhGH alone but did not compromise the endogenous secretion of GH. We conclude that rhIGF-I treatment augments cortical bone mass but does not further improve bone growth in rhGH-treated young, intact, female rats.

  8. Modeling place field activity with hierarchical slow feature analysis

    Directory of Open Access Journals (Sweden)

    Fabian eSchoenfeld

    2015-05-01

    Full Text Available In this paper we present six experimental studies from the literature on hippocampal place cells and replicate their main results in a computational framework based on the principle of slowness. Each of the chosen studies first allows rodents to develop stable place field activity and then examines a distinct property of the established spatial encoding, namely adaptation to cue relocation and removal; directional firing activity in the linear track and open field; and results of morphing and stretching the overall environment. To replicate these studies we employ a hierarchical Slow Feature Analysis (SFA network. SFA is an unsupervised learning algorithm extracting slowly varying information from a given stream of data, and hierarchical application of SFA allows for high dimensional input such as visual images to be processed efficiently and in a biologically plausible fashion. Training data for the network is produced in ratlab, a free basic graphics engine designed to quickly set up a wide range of 3D environments mimicking real life experimental studies, simulate a foraging rodent while recording its visual input, and training & sampling a hierarchical SFA network.

  9. Linear systems

    CERN Document Server

    Bourlès, Henri

    2013-01-01

    Linear systems have all the necessary elements (modeling, identification, analysis and control), from an educational point of view, to help us understand the discipline of automation and apply it efficiently. This book is progressive and organized in such a way that different levels of readership are possible. It is addressed both to beginners and those with a good understanding of automation wishing to enhance their knowledge on the subject. The theory is rigorously developed and illustrated by numerous examples which can be reproduced with the help of appropriate computation software. 60 exe

  10. Hierarchical vertical decompositions, ray shooting, and circular arc queries in simple polygons

    NARCIS (Netherlands)

    Oostrum, R. van; Ahn, Hee-Kap; Cheng, S.-W.; Golin, Mordecai

    1999-01-01

    A new hierarchical decomposition of a simple polygon is introduced. The hierarchy has depth O(log n), linear size, and its regions have maximum degree three. Using this hierarchy, circular ray shooting queries in a simple polygon can be answered in O(log* n) query time and O(nlogn) space. If the rad

  11. Discovering hierarchical structure in normal relational data

    DEFF Research Database (Denmark)

    Schmidt, Mikkel Nørgaard; Herlau, Tue; Mørup, Morten

    2014-01-01

    Hierarchical clustering is a widely used tool for structuring and visualizing complex data using similarity. Traditionally, hierarchical clustering is based on local heuristics that do not explicitly provide assessment of the statistical saliency of the extracted hierarchy. We propose a non-param...

  12. Discursive Hierarchical Patterning in Economics Cases

    Science.gov (United States)

    Lung, Jane

    2011-01-01

    This paper attempts to apply Lung's (2008) model of the discursive hierarchical patterning of cases to a closer and more specific study of Economics cases and proposes a model of the distinct discursive hierarchical patterning of the same. It examines a corpus of 150 Economics cases with a view to uncovering the patterns of discourse construction.…

  13. A Model of Hierarchical Key Assignment Scheme

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhigang; ZHAO Jing; XU Maozhi

    2006-01-01

    A model of the hierarchical key assignment scheme is approached in this paper, which can be used with any cryptography algorithm. Besides, the optimal dynamic control property of a hierarchical key assignment scheme will be defined in this paper. Also, our scheme model will meet this property.

  14. Galaxy formation through hierarchical clustering

    Science.gov (United States)

    White, Simon D. M.; Frenk, Carlos S.

    1991-01-01

    Analytic methods for studying the formation of galaxies by gas condensation within massive dark halos are presented. The present scheme applies to cosmogonies where structure grows through hierarchical clustering of a mixture of gas and dissipationless dark matter. The simplest models consistent with the current understanding of N-body work on dissipationless clustering, and that of numerical and analytic work on gas evolution and cooling are adopted. Standard models for the evolution of the stellar population are also employed, and new models for the way star formation heats and enriches the surrounding gas are constructed. Detailed results are presented for a cold dark matter universe with Omega = 1 and H(0) = 50 km/s/Mpc, but the present methods are applicable to other models. The present luminosity functions contain significantly more faint galaxies than are observed.

  15. Groups possessing extensive hierarchical decompositions

    CERN Document Server

    Januszkiewicz, T; Leary, I J

    2009-01-01

    Kropholler's class of groups is the smallest class of groups which contains all finite groups and is closed under the following operator: whenever $G$ admits a finite-dimensional contractible $G$-CW-complex in which all stabilizer groups are in the class, then $G$ is itself in the class. Kropholler's class admits a hierarchical structure, i.e., a natural filtration indexed by the ordinals. For example, stage 0 of the hierarchy is the class of all finite groups, and stage 1 contains all groups of finite virtual cohomological dimension. We show that for each countable ordinal $\\alpha$, there is a countable group that is in Kropholler's class which does not appear until the $\\alpha+1$st stage of the hierarchy. Previously this was known only for $\\alpha= 0$, 1 and 2. The groups that we construct contain torsion. We also review the construction of a torsion-free group that lies in the third stage of the hierarchy.

  16. Hierarchical networks of scientific journals

    CERN Document Server

    Palla, Gergely; Mones, Enys; Pollner, Péter; Vicsek, Tamás

    2015-01-01

    Scientific journals are the repositories of the gradually accumulating knowledge of mankind about the world surrounding us. Just as our knowledge is organised into classes ranging from major disciplines, subjects and fields to increasingly specific topics, journals can also be categorised into groups using various metrics. In addition to the set of topics characteristic for a journal, they can also be ranked regarding their relevance from the point of overall influence. One widespread measure is impact factor, but in the present paper we intend to reconstruct a much more detailed description by studying the hierarchical relations between the journals based on citation data. We use a measure related to the notion of m-reaching centrality and find a network which shows the level of influence of a journal from the point of the direction and efficiency with which information spreads through the network. We can also obtain an alternative network using a suitably modified nested hierarchy extraction method applied ...

  17. Adaptive Sampling in Hierarchical Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Knap, J; Barton, N R; Hornung, R D; Arsenlis, A; Becker, R; Jefferson, D R

    2007-07-09

    We propose an adaptive sampling methodology for hierarchical multi-scale simulation. The method utilizes a moving kriging interpolation to significantly reduce the number of evaluations of finer-scale response functions to provide essential constitutive information to a coarser-scale simulation model. The underlying interpolation scheme is unstructured and adaptive to handle the transient nature of a simulation. To handle the dynamic construction and searching of a potentially large set of finer-scale response data, we employ a dynamic metric tree database. We study the performance of our adaptive sampling methodology for a two-level multi-scale model involving a coarse-scale finite element simulation and a finer-scale crystal plasticity based constitutive law.

  18. Hierarchically Nanostructured Materials for Sustainable Environmental Applications

    Science.gov (United States)

    Ren, Zheng; Guo, Yanbing; Liu, Cai-Hong; Gao, Pu-Xian

    2013-11-01

    This article presents a comprehensive overview of the hierarchical nanostructured materials with either geometry or composition complexity in environmental applications. The hierarchical nanostructures offer advantages of high surface area, synergistic interactions and multiple functionalities towards water remediation, environmental gas sensing and monitoring as well as catalytic gas treatment. Recent advances in synthetic strategies for various hierarchical morphologies such as hollow spheres and urchin-shaped architectures have been reviewed. In addition to the chemical synthesis, the physical mechanisms associated with the materials design and device fabrication have been discussed for each specific application. The development and application of hierarchical complex perovskite oxide nanostructures have also been introduced in photocatalytic water remediation, gas sensing and catalytic converter. Hierarchical nanostructures will open up many possibilities for materials design and device fabrication in environmental chemistry and technology.

  19. A neural signature of hierarchical reinforcement learning.

    Science.gov (United States)

    Ribas-Fernandes, José J F; Solway, Alec; Diuk, Carlos; McGuire, Joseph T; Barto, Andrew G; Niv, Yael; Botvinick, Matthew M

    2011-07-28

    Human behavior displays hierarchical structure: simple actions cohere into subtask sequences, which work together to accomplish overall task goals. Although the neural substrates of such hierarchy have been the target of increasing research, they remain poorly understood. We propose that the computations supporting hierarchical behavior may relate to those in hierarchical reinforcement learning (HRL), a machine-learning framework that extends reinforcement-learning mechanisms into hierarchical domains. To test this, we leveraged a distinctive prediction arising from HRL. In ordinary reinforcement learning, reward prediction errors are computed when there is an unanticipated change in the prospects for accomplishing overall task goals. HRL entails that prediction errors should also occur in relation to task subgoals. In three neuroimaging studies we observed neural responses consistent with such subgoal-related reward prediction errors, within structures previously implicated in reinforcement learning. The results reported support the relevance of HRL to the neural processes underlying hierarchical behavior.

  20. Hierarchical Identity-Based Lossy Trapdoor Functions

    CERN Document Server

    Escala, Alex; Libert, Benoit; Rafols, Carla

    2012-01-01

    Lossy trapdoor functions, introduced by Peikert and Waters (STOC'08), have received a lot of attention in the last years, because of their wide range of applications in theoretical cryptography. The notion has been recently extended to the identity-based scenario by Bellare et al. (Eurocrypt'12). We provide one more step in this direction, by considering the notion of hierarchical identity-based lossy trapdoor functions (HIB-LTDFs). Hierarchical identity-based cryptography generalizes identitybased cryptography in the sense that identities are organized in a hierarchical way; a parent identity has more power than its descendants, because it can generate valid secret keys for them. Hierarchical identity-based cryptography has been proved very useful both for practical applications and to establish theoretical relations with other cryptographic primitives. In order to realize HIB-LTDFs, we first build a weakly secure hierarchical predicate encryption scheme. This scheme, which may be of independent interest, is...

  1. Hierarchically nanostructured materials for sustainable environmental applications

    Science.gov (United States)

    Ren, Zheng; Guo, Yanbing; Liu, Cai-Hong; Gao, Pu-Xian

    2013-01-01

    This review presents a comprehensive overview of the hierarchical nanostructured materials with either geometry or composition complexity in environmental applications. The hierarchical nanostructures offer advantages of high surface area, synergistic interactions, and multiple functionalities toward water remediation, biosensing, environmental gas sensing and monitoring as well as catalytic gas treatment. Recent advances in synthetic strategies for various hierarchical morphologies such as hollow spheres and urchin-shaped architectures have been reviewed. In addition to the chemical synthesis, the physical mechanisms associated with the materials design and device fabrication have been discussed for each specific application. The development and application of hierarchical complex perovskite oxide nanostructures have also been introduced in photocatalytic water remediation, gas sensing, and catalytic converter. Hierarchical nanostructures will open up many possibilities for materials design and device fabrication in environmental chemistry and technology. PMID:24790946

  2. Hierarchically Nanostructured Materials for Sustainable Environmental Applications

    Directory of Open Access Journals (Sweden)

    Zheng eRen

    2013-11-01

    Full Text Available This article presents a comprehensive overview of the hierarchical nanostructured materials with either geometry or composition complexity in environmental applications. The hierarchical nanostructures offer advantages of high surface area, synergistic interactions and multiple functionalities towards water remediation, environmental gas sensing and monitoring as well as catalytic gas treatment. Recent advances in synthetic strategies for various hierarchical morphologies such as hollow spheres and urchin-shaped architectures have been reviewed. In addition to the chemical synthesis, the physical mechanisms associated with the materials design and device fabrication have been discussed for each specific application. The development and application of hierarchical complex perovskite oxide nanostructures have also been introduced in photocatalytic water remediation, gas sensing and catalytic converter. Hierarchical nanostructures will open up many possibilities for materials design and device fabrication in environmental chemistry and technology.

  3. Hierarchically Nanoporous Bioactive Glasses for High Efficiency Immobilization of Enzymes

    DEFF Research Database (Denmark)

    He, W.; Min, D.D.; Zhang, X.D.

    2014-01-01

    Bioactive glasses with hierarchical nanoporosity and structures have been heavily involved in immobilization of enzymes. Because of meticulous design and ingenious hierarchical nanostructuration of porosities from yeast cell biotemplates, hierarchically nanostructured porous bioactive glasses can...

  4. Hierarchical mutual information for the comparison of hierarchical community structures in complex networks

    CERN Document Server

    Perotti, Juan Ignacio; Caldarelli, Guido

    2015-01-01

    The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the {\\it hierarchical mutual information}, which is a generalization of the traditional mutual information, and allows to compare hierarchical partitions and hierarchical community structures. The {\\it normalized} version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here, the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies, and on the hierarchical ...

  5. Identification and Characterization of a Gene stp17 Located on the Linear Plasmid pBSSB1 as an Enhanced Gene of Growth and Motility in Salmonella enterica Serovar Typhi

    Science.gov (United States)

    Zhang, Haifang; Zhu, Yunxia; Xie, Xiaofang; Wang, Min; Du, Hong; Xu, Shungao; Zhang, Ying; Gong, Mingyu; Ni, Bin; Xu, Huaxi; Huang, Xinxiang

    2016-01-01

    The linear plasmid pBSSB1 mediates the flagellar phase variation in H:z66 positive Salmonella enterica serovar Typhi (S. Typhi). The gene named stp17 (S. Typhi plasmid number 17 gene) is located on pBSSB1 and encodes the protein STP17. The expression pattern at the protein-level and function of STP17 remains unknown. In this study, the recombinant protein STP17His6 was expressed, purified and used to prepare the polyclonal anti-STP17 antibody. We detected protein-level expression of stp17 in S. Typhi and further investigated the protein expression characteristics of stp17 in different growth phases by western blot analysis. The effects of STP17 on bacterial growth and motility were analyzed. In addition, the structure of STP17 was predicted and the active site of STP17 was identified by site-directed mutagenesis. The results showed that STP17 was expressed stably in the wild type strain of S. Typhi. STP17 expression at the protein level peaks when cultures reach an OD600 value of 1.2. The growth rate and motility of the Δstp17 strain were significantly decreased compared with the wild type strain (P characteristics of STP17 in S. Typhi, showing that STP17 promotes bacterial growth and motility, which may be associated with its potential ATPase activity. PMID:27761429

  6. Alligator osteoderms: Mechanical behavior and hierarchical structure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Irene H. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Yang, Wen, E-mail: wey005@eng.ucsd.edu [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Departments of Mechanical and Aerospace Engineering and Nanoengineering, University of California, San Diego, La Jolla, CA 92093 (United States)

    2014-02-01

    Osteoderms are bony scutes embedded underneath the dermal layers of the skin acting as a protection of the alligator (Archosauria: Crocodylia) internal organs and tissues. Additionally, these scutes function as an aid in temperature regulation. The scutes are inter-linked by fibrous connective tissue. They have properties similar to bone and thus have the necessary toughness to provide protection against predators. The scutes consist of hydroxyapatite and have a porosity of approximately 12%. They have a disc-like morphology with a ridge along the middle of the plate, called the keel; the outer perimeter of the disc has depressions, grooves, and jagged edges which anchor the collagen and act as sutures. Computerized tomography reveals the pattern of elongated pores, which emanate from the keel in a radial pattern. Micro-indentation measurements along the cross-section show a zigzag behavior due to the porosity. Compression results indicate that the axial direction is the strongest (UTS ∼ 67 MPa) and toughest (11 MJ/m{sup 3}); this is the orientation in which they undergo the largest external compression forces from predator teeth. Toughening mechanisms are identified through observation of the damage progression and interpreted in mechanistic terms. They are: flattening of pores, microcrack opening, and microcrack growth and coalescence. Collagen plays an essential role in toughening and plasticity by providing bridges that impede the opening of the cracks and prevent their growth. - Highlights: • We characterized the hierarchical structure of alligator scute. • The anisotropic mechanical behavior of alligator scute was studied. • Toughening mechanisms were identified at the micro- and nano-levels.

  7. Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    Weiyan Meng; Yanmin Zhou; Yanjing Zhang; Qing Cai; Liming Yang; Jinghui Zhao; Chnnyan Li

    2011-01-01

    In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hierarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching (EE). MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched (SLA) as well as Machined (M) surfaces respectively. The results show significant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

  8. Generalizing Fisher's “reproductive value”: “Incipient” and “penultimate” reproductive-value functions when environment limits growth; linear approximants for nonlinear Mendelian mating models†

    Science.gov (United States)

    Samuelson, Paul A.

    1978-01-01

    In the usual Darwinian case in which struggle for existence leads to density limitations on the environment's carrying capacity, R. A. Fisher's reproductive-value concept reduces to zero for every initial age group. To salvage some meaning for Fisher's notion, two variant reproductive-value concepts are defined here: an “incipient reproductive-value function,” applicable to a system's early dilute stage when density effects are still ignorable; and a “second-order penultimate reproductive-value function,” linking to a system's initial conditions near equilibrium its much later small deviations from carrying-capacity equilibrium. Also, slowly changing age-structured mortality and fertility parameters of Lotka and Mendelian mating systems are shown to suggest linear reproductive-value surrogates that provide approximations for truly nonlinear diploid and haploid models. PMID:16592600

  9. Non-linear model of cancer growth and metastasis: a limiting nutrient as a major determinant of tumor shape and diffusion.

    Science.gov (United States)

    Pescarmona, G P; Scalerandi, M; Delsanto, P P; Condat, C A

    1999-12-01

    A new approach for modelling the spatio-temporal evolution of tumors is presented. To test its validity, a very basic model is considered, which, in spite of its simplicity, is capable of generating a multiplicity of morphologies and growth and migration rates. From an in-vivo scenario of basic life processes, cancer cell proliferation is described as a competition for basic nutrients. The chosen mathematical treatment and simulation techniques permit a direct implementation of the local nonlinear couplings existing between the various cell populations and the free and bound nutrient concentration. A discussion of the results and proposed improvements and applications of the model is also presented.

  10. Inference in HIV dynamics models via hierarchical likelihood

    CERN Document Server

    Commenges, D; Putter, H; Thiebaut, R

    2010-01-01

    HIV dynamical models are often based on non-linear systems of ordinary differential equations (ODE), which do not have analytical solution. Introducing random effects in such models leads to very challenging non-linear mixed-effects models. To avoid the numerical computation of multiple integrals involved in the likelihood, we propose a hierarchical likelihood (h-likelihood) approach, treated in the spirit of a penalized likelihood. We give the asymptotic distribution of the maximum h-likelihood estimators (MHLE) for fixed effects, a result that may be relevant in a more general setting. The MHLE are slightly biased but the bias can be made negligible by using a parametric bootstrap procedure. We propose an efficient algorithm for maximizing the h-likelihood. A simulation study, based on a classical HIV dynamical model, confirms the good properties of the MHLE. We apply it to the analysis of a clinical trial.

  11. Likelihood Approximation With Hierarchical Matrices For Large Spatial Datasets

    KAUST Repository

    Litvinenko, Alexander

    2017-09-03

    We use available measurements to estimate the unknown parameters (variance, smoothness parameter, and covariance length) of a covariance function by maximizing the joint Gaussian log-likelihood function. To overcome cubic complexity in the linear algebra, we approximate the discretized covariance function in the hierarchical (H-) matrix format. The H-matrix format has a log-linear computational cost and storage O(kn log n), where the rank k is a small integer and n is the number of locations. The H-matrix technique allows us to work with general covariance matrices in an efficient way, since H-matrices can approximate inhomogeneous covariance functions, with a fairly general mesh that is not necessarily axes-parallel, and neither the covariance matrix itself nor its inverse have to be sparse. We demonstrate our method with Monte Carlo simulations and an application to soil moisture data. The C, C++ codes and data are freely available.

  12. Hierarchical population model with a carrying capacity distribution

    CERN Document Server

    Indekeu, J O

    2002-01-01

    A time- and space-discrete model for the growth of a rapidly saturating local biological population $N(x,t)$ is derived from a hierarchical random deposition process previously studied in statistical physics. Two biologically relevant parameters, the probabilities of birth, $B$, and of death, $D$, determine the carrying capacity $K$. Due to the randomness the population depends strongly on position, $x$, and there is a distribution of carrying capacities, $\\Pi (K)$. This distribution has self-similar character owing to the imposed hierarchy. The most probable carrying capacity and its probability are studied as a function of $B$ and $D$. The effective growth rate decreases with time, roughly as in a Verhulst process. The model is possibly applicable, for example, to bacteria forming a "towering pillar" biofilm. The bacteria divide on randomly distributed nutrient-rich regions and are exposed to random local bactericidal agent (antibiotic spray). A gradual overall temperature change away from optimal growth co...

  13. A Multi-Objective Input–Output Linear Model for Water Supply, Economic Growth and Environmental Planning in Resource-Based Cities

    Directory of Open Access Journals (Sweden)

    Wenlan Ke

    2016-02-01

    Full Text Available Water resource and environment capacity have become two of the most important restrictions for sustainable development in resource-based cities whose leading industries are the exploitation and processing of resources. Taking Ordos in China as an example, this article constructs an integrated model combining a multi-objective optimization model with input–output analysis to achieve the tradeoffs between economic growth, water utilization and environmental protection. This dynamic model includes socioeconomic, water supply–demand, water quality control, air quality control, energy consumption control and integrated policy sub-models. These six sub-models interact with each other. After simulation, this article proposes efficient solutions on industrial restructuring by maximizing the Gross Regional Product of Ordos from 394.3 in 2012 to 785.1 billion RMB in 2025 with a growth rate of 6.4% annually; and presents a water supply plan by maximizing the proportion of reclaimed water from 2% to 6.3% through sewage treatment technology selection and introduction, and effective water allocation. Meanwhile, the environmental impacts are all in line with the planning targets. This study illustrates that the integrated modeling is generic and can be applied to any region suffering uncoordinated development issues and can serve as a pre-evaluation approach for conducting early warning research to offer suggestions for government decision-making.

  14. A 3D AgCl hierarchical superstructure synthesized by a wet chemical oxidation method.

    Science.gov (United States)

    Lou, Zaizhu; Huang, Baibiao; Ma, Xiangchao; Zhang, Xiaoyang; Qin, Xiaoyan; Wang, Zeyan; Dai, Ying; Liu, Yuanyuan

    2012-12-07

    A novel 3D AgCl hierarchical superstructure, with fast growth along the 〈111〉 directions of cubic seeds, is synthesized by using a wet chemical oxidation method. The morphological structures and the growth process are investigated by scanning electron microscopy and X-ray diffraction. The crystal structures are analyzed by their crystallographic orientations. The surface energy of AgCl facets {100}, {110}, and {111} with absorbance of Cl(-) ions is studied by density functional theory calculations. Based on the experimental and computational results, a plausible mechanism is proposed to illustrate the formation of the 3D AgCl hierarchical superstructures. With more active sites, the photocatalytic activity of the 3D AgCl hierarchical superstructures is better than those of concave and cubic ones in oxygen evolution under irradiation by visible light.

  15. Object recognition with hierarchical discriminant saliency networks

    Directory of Open Access Journals (Sweden)

    Sunhyoung eHan

    2014-09-01

    Full Text Available The benefits of integrating attention and object recognition are investigated. While attention is frequently modeled as pre-processor for recognition, we investigate the hypothesis that attention is an intrinsic component of recognition and vice-versa. This hypothesis is tested with a recognitionmodel, the hierarchical discriminant saliency network (HDSN, whose layers are top-down saliency detectors, tuned for a visual class according to the principles of discriminant saliency. The HDSN has two possible implementations. In a biologically plausible implementation, all layers comply with the standard neurophysiological model of visual cortex, with sub-layers of simple and complex units that implement a combination of filtering, divisive normalization, pooling, and non-linearities. In a neuralnetwork implementation, all layers are convolutional and implement acombination of filtering, rectification, and pooling. The rectificationis performed with a parametric extension of the now popular rectified linearunits (ReLUs, whose parameters can be tuned for the detection of targetobject classes. This enables a number of functional enhancementsover neural network models that lack a connection to saliency, including optimal feature denoising mechanisms for recognition, modulation ofsaliency responses by the discriminant power of the underlying features,and the ability to detect both feature presence and absence.In either implementation, each layer has a precise statistical interpretation, and all parameters are tuned by statistical learning. Each saliency detection layer learns more discriminant saliency templates than its predecessors and higher layers have larger pooling fields. This enables the HDSN to simultaneously achieve high selectivity totarget object classes and invariance. The resulting performance demonstrates benefits for all the functional enhancements of the HDSN.

  16. Hierarchically structured, nitrogen-doped carbon membranes

    KAUST Repository

    Wang, Hong

    2017-08-03

    The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced on a large-scale approach. The unique HNDCM holds great promise as components in separation and advanced carbon devices because they could offer unconventional fluidic transport phenomena on the nanoscale. Overall, the invention set forth herein covers a hierarchically structured, nitrogen-doped carbon membranes and methods of making and using such a membranes.

  17. A Model for Slicing JAVA Programs Hierarchically

    Institute of Scientific and Technical Information of China (English)

    Bi-Xin Li; Xiao-Cong Fan; Jun Pang; Jian-Jun Zhao

    2004-01-01

    Program slicing can be effectively used to debug, test, analyze, understand and maintain objectoriented software. In this paper, a new slicing model is proposed to slice Java programs based on their inherent hierarchical feature. The main idea of hierarchical slicing is to slice programs in a stepwise way, from package level, to class level, method level, and finally up to statement level. The stepwise slicing algorithm and the related graph reachability algorithms are presented, the architecture of the Java program Analyzing Tool (JATO) based on hierarchical slicing model is provided, the applications and a small case study are also discussed.

  18. Hierarchical analysis of acceptable use policies

    Directory of Open Access Journals (Sweden)

    P. A. Laughton

    2008-01-01

    Full Text Available Acceptable use policies (AUPs are vital tools for organizations to protect themselves and their employees from misuse of computer facilities provided. A well structured, thorough AUP is essential for any organization. It is impossible for an effective AUP to deal with every clause and remain readable. For this reason, some sections of an AUP carry more weight than others, denoting importance. The methodology used to develop the hierarchical analysis is a literature review, where various sources were consulted. This hierarchical approach to AUP analysis attempts to highlight important sections and clauses dealt with in an AUP. The emphasis of the hierarchal analysis is to prioritize the objectives of an AUP.

  19. Hierarchical modeling and analysis for spatial data

    CERN Document Server

    Banerjee, Sudipto; Gelfand, Alan E

    2003-01-01

    Among the many uses of hierarchical modeling, their application to the statistical analysis of spatial and spatio-temporal data from areas such as epidemiology And environmental science has proven particularly fruitful. Yet to date, the few books that address the subject have been either too narrowly focused on specific aspects of spatial analysis, or written at a level often inaccessible to those lacking a strong background in mathematical statistics.Hierarchical Modeling and Analysis for Spatial Data is the first accessible, self-contained treatment of hierarchical methods, modeling, and dat

  20. Multi-scaling hierarchical structure analysis on the sequence of E. coli complete genome

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We have applied the newly developed hierarchical structure theory for complex systems to analyze the multi-scaling structures of the nucleotide density distribution along a linear DNA sequence from the complete Escherichia coli genome. The hierarchical symmetry in the nucleotide density distribution was demonstrated. In particular, we have shown that the G, C density distribution that represents a strong H-bonding between the two DNA chains is more coherent with smaller similarity parameter compared to that of A, T density distribution, indicating a better organized multi-scaling fluctuation field for G, C density distribution along the genome sequence. The biological significance of these findings is under investigation.