A Model and Questionnaire of Language Identity in Iran: A Structural Equation Modelling Approach
ERIC Educational Resources Information Center
Khatib, Mohammad; Rezaei, Saeed
2013-01-01
This study consisted of three main phases including the development of a hypothesised model of language identity in Iran, developing and validating a questionnaire based on this model and finally testing the model based on the questionnaire data. In the first phase of this research, a hypothesised model of language identity in Iran was developed…
De Bondt, Niki; Van Petegem, Peter
2015-01-01
The Overexcitability Questionnaire-Two (OEQ-II) measures the degree and nature of overexcitability, which assists in determining the developmental potential of an individual according to Dabrowski's Theory of Positive Disintegration. Previous validation studies using frequentist confirmatory factor analysis, which postulates exact parameter constraints, led to model rejection and a long series of model modifications. Bayesian structural equation modeling (BSEM) allows the application of zero-mean, small-variance priors for cross-loadings, residual covariances, and differences in measurement parameters across groups, better reflecting substantive theory and leading to better model fit and less overestimation of factor correlations. Our BSEM analysis with a sample of 516 students in higher education yields positive results regarding the factorial validity of the OEQ-II. Likewise, applying BSEM-based alignment with approximate measurement invariance, the absence of non-invariant factor loadings and intercepts across gender is supportive of the psychometric quality of the OEQ-II. Compared to males, females scored significantly higher on emotional and sensual overexcitability, and significantly lower on psychomotor overexcitability.
Paper to Electronic Questionnaires: Effects on Structured Questionnaire Forms
NASA Technical Reports Server (NTRS)
Trujillo, Anna C.
2009-01-01
With the use of computers, paper questionnaires are being replaced by electronic questionnaires. The formats of traditional paper questionnaires have been found to effect a subject's rating. Consequently, the transition from paper to electronic format can subtly change results. The research presented begins to determine how electronic questionnaire formats change subjective ratings. For formats where subjects used a flow chart to arrive at their rating, starting at the worst and middle ratings of the flow charts were the most accurate but subjects took slightly more time to arrive at their answers. Except for the electronic paper format, starting at the worst rating was the most preferred. The paper and electronic paper versions had the worst accuracy. Therefore, for flowchart type of questionnaires, flowcharts should start at the worst rating and work their way up to better ratings.
Structural Validity of the Multifactor Leadership Questionnaire.
ERIC Educational Resources Information Center
Tepper, Bennett J.; Percy, Paul M.
1994-01-01
Two studies with 290 college students and 95 business managers investigated the latent structure of items from the Multifactor Leadership Questionnaire (MLQ). Results support models in which transformational and transactional leadership items load on separate factors and suggest that charismatic and inspirational leadership scales converge for…
ERIC Educational Resources Information Center
Aitken, Madison; Martinussen, Rhonda; Wolfe, Richard G.; Tannock, Rosemary
2015-01-01
The Strengths and Difficulties Questionnaire (SDQ) is a 25-item screening measure for emotional and behavioral problems in children and adolescents aged 4 to 16. Structural equation modeling was used to test the five-factor structure of teacher and parent ratings on the British version of the SDQ in a community sample of 501 Canadian children aged…
Structural Equation Model Trees
ERIC Educational Resources Information Center
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2013-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
Structural Equation Model Trees
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2015-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789
Factorial Structure of the Anxiety Control Questionnaire in Chinese Adolescents
ERIC Educational Resources Information Center
Shujuan, Wang; Meihua, Qian; Jianxin, Zhang
2009-01-01
This article examines the psychometric structure of the Anxiety Control Questionnaire (ACQ) in Chinese adolescents. With the data collected from 212 senior high school students (94 females, 110 males, 8 unknown), seven models are tested using confirmatory factor analyses in the framework of the multitrait-multimethod strategy. Results indicate…
Structural and Convergent Validity of the Homework Performance Questionnaire
ERIC Educational Resources Information Center
Pendergast, Laura L.; Watkins, Marley W.; Canivez, Gary L.
2014-01-01
Homework is a requirement for most school-age children, but research on the benefits and drawbacks of homework is limited by lack of psychometrically sound measurement of homework performance. This study examined the structural and convergent validity of scores from the newly developed Homework Performance Questionnaire -- Teacher Scale (HPQ-T).…
The Structure and Validity of the Multidimensional Social Support Questionnaire
ERIC Educational Resources Information Center
Hardesty, Patrick H.; Richardson, George B.
2012-01-01
The factor structure and concurrent validity of the Multidimensional Social Support Questionnaire, a brief measure of perceived social support for use with adolescents, was examined. Findings suggest that four dimensions of perceived social support may yield more information than assessments of the unitary construct of support. (Contains 8 tables…
Generalized Multilevel Structural Equation Modeling
ERIC Educational Resources Information Center
Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew
2004-01-01
A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…
The Brief Aggression Questionnaire: Structure, Validity, Reliability, and Generalizability.
Webster, Gregory D; DeWall, C Nathan; Pond, Richard S; Deckman, Timothy; Jonason, Peter K; Le, Bonnie M; Nichols, Austin Lee; Schember, Tatiana Orozco; Crysel, Laura C; Crosier, Benjamin S; Smith, C Veronica; Paddock, E Layne; Nezlek, John B; Kirkpatrick, Lee A; Bryan, Angela D; Bator, Renée J
2015-01-01
In contexts that increasingly demand brief self-report measures (e.g., experience sampling, longitudinal and field studies), researchers seek succinct surveys that maintain reliability and validity. One such measure is the 12-item Brief Aggression Questionnaire (BAQ; Webster et al., 2014), which uses 4 3-item subscales: Physical Aggression, Verbal Aggression, Anger, and Hostility. Although prior work suggests the BAQ's scores are reliable and valid, we addressed some lingering concerns. Across 3 studies (N = 1,279), we found that the BAQ had a 4-factor structure, possessed long-term test-retest reliability across 12 weeks, predicted differences in behavioral aggression over time in a laboratory experiment, generalized to a diverse nonstudent sample, and showed convergent validity with a displaced aggression measure. In addition, the BAQ's 3-item Anger subscale showed convergent validity with a trait anger measure. We discuss the BAQ's potential reliability, validity, limitations, and uses as an efficient measure of aggressive traits. PMID:26055531
Bifactor structure of the schizotypal personality questionnaire (SPQ).
Preti, Antonio; Siddi, Sara; Vellante, Marcello; Scanu, Rosanna; Muratore, Tamara; Gabrielli, Mersia; Tronci, Debora; Masala, Carmelo; Petretto, Donatella Rita
2015-12-30
The schizotypal personality questionnaire (SPQ) is used to characterize schizotypy, a complex construct helpful for the investigation of schizophrenia-related psychopathology and putative endophenotypes. The SPQ factor structure at item level has been rarely replicated and no study had tested a bifactor model of the SPQ so far. The unidimensional, the correlated, the second-order and the bifactor models of the SPQ were tested to evaluate whether the items converge into a major single factor defining the schizotypy-proneness of the participants, to be used for grouping purpose. Parallel principal component analysis (PCA) and confirmatory factor analysis (CFA) were used to determine the optimal number of factors and components in a cross-sectional, survey design involving 649 college students (males: 47%). The first-order, nine-subscale model was confirmed by CFA in the whole sample. The best evidence from parallel PCA in the training set was in favor of a two-factor model; the bifactor implementation of this model showed good fit in the subsequent CFA. Two main dimensions of positive and negative symptoms underlie schizotypy in non-clinical samples, entailing specific risk of psychosis. On a measurement level, the study provided support for the use of the total scores of the SPQ to characterize schizotypy. PMID:26607431
ERIC Educational Resources Information Center
Harris, Sandra M.; Halpin, Glennelle
The purpose of this study was to investigate the factor structure of a Factors Influencing Pursuit of Higher Education (FIPHE) Questionnaire which addresses factors influencing a person's decision to pursue higher education. Researchers used a literature-based, rational factors approach to develop the questionnaire; the three-part study included a…
ERIC Educational Resources Information Center
Cui, Lixia; Lin, Wenwen; Oei, Tian P. S.
2011-01-01
This study investigated cross-cultural differences in the factor structure and psychometric properties of the Young Schema Questionnaire (short form; YSQ-SF). The participants were 712 Chinese undergraduate students. The total sample was randomly divided into two sub-samples. Exploratory Factor Analysis (EFA) was conducted on questionnaire results…
Cosi Muñoz, Sandra; Vigil-Colet, Andreu; Canals Sans, Josepa
2009-02-01
Development of the proactive/reactive questionnaire for teachers: factor structure and psychometric properties. The main purpose of this study was to develop a proactive/reactive aggression questionnaire for children in Spanish, reported by teachers. To develop the questionnaire, we selected eight items from the most widely used questionnaires in English using the criteria of a group of experts. Exploratory factor analysis on a sample of 267 children yielded two dimensions, one of proactive and the other of reactive aggression, consisting of four items each. Both scales showed good reliability and were related to an external criterion such as academic performance. PMID:19178871
Structural Analysis of the Resident Assistant Cultural Diversity Questionnaire
ERIC Educational Resources Information Center
Johnson, Vanessa D.; Kang, Young-Shin; Thompson, George F.
2011-01-01
This study investigated the five-factor structure of the Resident Assistant Cultural Diversity (RACD) instrument, which assesses resident assistant (RA) confidence in addressing issues of cultural diversity in college and university residence halls. The instrument has five components that explore RA confidence: (1) belief in the need for cultural…
Structural Equation Modeling of Multivariate Time Series
ERIC Educational Resources Information Center
du Toit, Stephen H. C.; Browne, Michael W.
2007-01-01
The covariance structure of a vector autoregressive process with moving average residuals (VARMA) is derived. It differs from other available expressions for the covariance function of a stationary VARMA process and is compatible with current structural equation methodology. Structural equation modeling programs, such as LISREL, may therefore be…
Reducing the Length of Questionnaires through Structurally Incomplete Designs: An Illustration
ERIC Educational Resources Information Center
Smits, Niels; Vorst, Harrie C. M.
2007-01-01
This paper serves as an illustration of the usefulness of structurally incomplete designs as an approach to reduce the length of educational questionnaires. In structurally incomplete test designs, respondents only fill out a subset of the total item set, while all items are still provided to the whole sample. The scores on the unadministered…
ERIC Educational Resources Information Center
Andrei, Federica; Smith, Martin M.; Surcinelli, Paola; Baldaro, Bruno; Saklofske, Donald H.
2016-01-01
This study investigated the structure and validity of the Italian translation of the Trait Emotional Intelligence Questionnaire. Data were self-reported from 227 participants. Confirmatory factor analysis supported the four-factor structure of the scale. Hierarchical regressions also demonstrated its incremental validity beyond demographics, the…
The Specific Analysis of Structural Equation Models
ERIC Educational Resources Information Center
McDonald, Roderick P.
2004-01-01
Conventional structural equation modeling fits a covariance structure implied by the equations of the model. This treatment of the model often gives misleading results because overall goodness of fit tests do not focus on the specific constraints implied by the model. An alternative treatment arising from Pearl's directed acyclic graph theory…
Roedler, Frauke S; Pohl, Sabine; Oechtering, Gerhard U
2013-12-01
Brachycephalic syndrome (BS) is a complex canine disease, which is characterized by diverse clinical signs primarily involving the respiratory and gastrointestinal systems. Through a structured owner questionnaire, the present study investigated how owners perceived the frequency and severity of a broad spectrum of welfare-relevant impairments caused by this hereditary disease. One hundred owners of brachycephalic dogs (Pugs and French bulldogs) referred for surgical treatment of BS completed the questionnaire. As a basis for comparison, 20 owners of mesocephalic dogs also completed part of the questionnaire. Questionnaire responses revealed that in addition to the well-known respiratory signs, brachycephalic dogs experienced severe exercise intolerance and prolonged recovery time after physical exercise (88%), significant heat sensitivity (more severe signs at temperatures above 19°C; 50%) and a variety of sleep problems (56%). To our knowledge, this is the first study using a structured owner questionnaire specifically to investigate a broad range of problems caused by selective breeding for brachycephaly. In particular, decreased exercise tolerance, increased recovery time due to heat intolerance and the extent of sleep problems have either been underestimated in the past, or have severely worsened over recent generations of dogs. The extent and severity of clinical signs and their impact on quality of life greatly exceeded our expectations. This study emphasizes the major impact that selective breeding for extreme brachycephalic features has on animal welfare. PMID:24176279
Factor Structure of the Children's Behavior Questionnaire in Children with Williams Syndrome
ERIC Educational Resources Information Center
Leyfer, Ovsanna; John, Angela E.; Woodruff-Borden, Janet; Mervis, Carolyn B.
2012-01-01
To examine the factor structure of temperament in 5-10-year-olds with Williams syndrome, an exploratory factor analysis was conducted on the responses of parents of 192 children on the children's behavior questionnaire. Four factors were identified. Two corresponded to factors reported for typically developing children: effortful control and…
Temperament factor structure in fragile X syndrome: the children's behavior questionnaire.
Roberts, Jane E; Tonnsen, Bridgette L; Robinson, Marissa; McQuillin, Samuel D; Hatton, Deborah D
2014-02-01
Early patterns of temperament lay the foundation for a variety of developmental constructs such as self-regulation, psychopathology, and resilience. Children with fragile X syndrome (FXS) display unique patterns of temperament compared to age-matched clinical and non-clinical samples, and early patterns of temperament have been associated with later anxiety in this population. Despite these unique patterns in FXS and recent reports of atypical factor structure of temperament questionnaires in Williams Syndrome (Leyfer, John, Woodruff-Borden, & Mervis, 2012), no studies have examined the latent factor structure of temperament scales in FXS to ensure measurement validity in this sample. The present study used confirmatory factor analysis to examine the factor structure of a well-validated parent-reported temperament questionnaire, the Children's Behavior Questionnaire (Rothbart, Ahadi, Hershey, & Fisher, 2001), in a sample of 90 males with FXS ages 3-9 years. Our data produced a similar, but not identical, three-factor model that retained the original CBQ factors of negative affectivity, effortful control, and extraversion/surgency. In particular, our FXS sample demonstrated stronger factor loadings for fear and shyness than previously reported loadings in non-clinical samples, consistent with reports of poor social approach and elevated anxiety in this population. Although the original factor structure of the Children's Behavior Questionnaire is largely retained in children with FXS, differences in factor loading magnitudes may reflect phenotypic characteristics of the syndrome. These findings may inform future developmental and translational research efforts. PMID:24380785
Bayesian Lasso for Semiparametric Structural Equation Models
Guo, Ruixin; Zhu, Hongtu; Chow, Sy-Miin; Ibrahim, Joseph G.
2011-01-01
Summary There has been great interest in developing nonlinear structural equation models and associated statistical inference procedures, including estimation and model selection methods. In this paper a general semiparametric structural equation model (SSEM) is developed in which the structural equation is composed of nonparametric functions of exogenous latent variables and fixed covariates on a set of latent endogenous variables. A basis representation is used to approximate these nonparametric functions in the structural equation and the Bayesian Lasso method coupled with a Markov Chain Monte Carlo (MCMC) algorithm is used for simultaneous estimation and model selection. The proposed method is illustrated using a simulation study and data from the Affective Dynamics and Individual Differences (ADID) study. Results demonstrate that our method can accurately estimate the unknown parameters and correctly identify the true underlying model. PMID:22376150
2009-01-01
Background Self-reported data are a common source of information about drug exposure. Modes of data collection differ considerably and the questionnaire's structure may affect prevalence estimates. We compared the recall of medication use evaluated by means of two questionnaires differing in structure and length. Methods Drug utilization was assessed by two alternative versions of a questionnaire (A – 4 pages, including specific questions for 12 indications/pharmacological groups and one question for "other medicines"; B – 1 page, including 1 open-ended question to cover overall drug consumption). Each of 32 classes in a private University in Maputo, Mozambique, was randomly assigned questionnaire A (233 participants) or B (276 participants). Logistic regression (allowing for clustering by classroom) was used to compare the two groups in terms of socio-demographic characteristics and medication used during the previous month. Results Overall, 67.4% of the subjects had used at least one drug during the previous month. The following prevalences were greater among participants completing questionnaire A: use of drugs from two or more pharmacological groups (60.5% vs. 34.4%, p < 0.001), use of two or more drugs (66.2% vs. 43.0%, p < 0.001), and use of antibiotics (14.6% vs. 6.9%, p = 0.001), antifungals (9.4% vs. 4.0%, p = 0.013), antiparasitics (5.6% vs. 1.8%, p = 0.031) and antacids (8.6% vs. 3.6%, p = 0.024). Information about duration of treatment and medical advice was more complete with version A. Conclusion The indication/drug-specific questions (questionnaire A) revealed a significantly higher prevalence of use of medicines – antibiotics, antifungals, antiparasitics and antacids – without compromising the completeness of the information. PMID:19563651
Psychometric properties and factor structure of an L2 reading motivation questionnaire.
Kim, Hee-jung; Choi, Sunhee
2014-01-01
The purpose of this study is to investigate the psychometric properties and factor structure of a popular second language reading motivation questionnaire developed by Mori (2002). 550 first year high school students in Korea answered the 30-item questionnaire which consists of statements indicating different degrees of English reading motivation. Exploratory factor analysis was conducted with principal axis factoring and promax rotation, which yielded a four-factor solution. The factors included 'Intercultural and Intellectual Orientation', 'Reading Efficacy', 'Intrinsic Motivation', and 'Negative Attitudes'. The results supported the multidimensionality of the construct of L2 reading motivation, but could not replicate the nine factor structure which was originally proposed by Mori. The implications for further research on L2 reading motivation and development of a more valid L2 reading scale are discussed. PMID:24704649
Raffan, Eleanor; Smith, Stephen P; O'Rahilly, Stephen; Wardle, Jane
2015-01-01
Background. Dogs are compelling models in which to study obesity since the condition shares many characteristics between humans and dogs. Differences in eating behaviour are recognised to contribute to obesity susceptibility in other species but this has not been systematically studied in dogs. Aim. To develop and validate an owner-reported measure of canine eating behaviour and owner or dog related factors which can alter the development of obesity. Further, to then test variation in food-motivation in dogs and its association with obesity and owner management. Methods. Owner interviews, a literature review and existing human appetite scales were used to identify relevant topics and generate items for the questionnaire. Following a pilot phase, a 75 item online questionnaire was distributed via social media. Responses from 302 dog/owner dyads were analysed and factor structure and descriptive statistics calculated. Results were compared with descriptions of dog behaviour and management from a subset of respondents during semi-structured interviews. The optimum questions were disseminated as a 34 item final questionnaire completed by 213 owners, with a subset of respondents repeating the questionnaire 3 weeks later to assess test-retest reliability. Results. Analysis of responses to the final questionnaire relating to 213 dog/owner dyads showed a coherent factor structure and good test-retest reliability. There were three dog factors (food responsiveness and satiety, lack of selectivity, Interest in food), four owner factors (owner motivation to control dog weight, owner intervention to control dog weight, restriction of human food, exercise taken) and two dog health factors (signs of gastrointestinal disease, current poor health). Eating behaviour differed between individuals and between breed groups. High scores on dog factors (high food-motivation) and low scores on owner factors (less rigorous control of diet/exercise) were associated with obesity. Owners of more highly food-motivated dogs exerted more control over their dogs' food intake than those of less food-motivated dogs. Conclusions. The DORA questionnaire is a reliable and informative owner-reported measure of canine eating behaviour and health and management factors which can be associated with obesity development. The tool will be applicable to study of the canine obesity model and to clinical veterinarians. Results revealed eating behaviour to be similarly associated with obesity as exercise and owners giving titbits. PMID:26468435
Smith, Stephen P.; O’Rahilly, Stephen; Wardle, Jane
2015-01-01
Background. Dogs are compelling models in which to study obesity since the condition shares many characteristics between humans and dogs. Differences in eating behaviour are recognised to contribute to obesity susceptibility in other species but this has not been systematically studied in dogs. Aim. To develop and validate an owner-reported measure of canine eating behaviour and owner or dog related factors which can alter the development of obesity. Further, to then test variation in food-motivation in dogs and its association with obesity and owner management. Methods. Owner interviews, a literature review and existing human appetite scales were used to identify relevant topics and generate items for the questionnaire. Following a pilot phase, a 75 item online questionnaire was distributed via social media. Responses from 302 dog/owner dyads were analysed and factor structure and descriptive statistics calculated. Results were compared with descriptions of dog behaviour and management from a subset of respondents during semi-structured interviews. The optimum questions were disseminated as a 34 item final questionnaire completed by 213 owners, with a subset of respondents repeating the questionnaire 3 weeks later to assess test–retest reliability. Results. Analysis of responses to the final questionnaire relating to 213 dog/owner dyads showed a coherent factor structure and good test–retest reliability. There were three dog factors (food responsiveness and satiety, lack of selectivity, Interest in food), four owner factors (owner motivation to control dog weight, owner intervention to control dog weight, restriction of human food, exercise taken) and two dog health factors (signs of gastrointestinal disease, current poor health). Eating behaviour differed between individuals and between breed groups. High scores on dog factors (high food-motivation) and low scores on owner factors (less rigorous control of diet/exercise) were associated with obesity. Owners of more highly food-motivated dogs exerted more control over their dogs’ food intake than those of less food-motivated dogs. Conclusions. The DORA questionnaire is a reliable and informative owner-reported measure of canine eating behaviour and health and management factors which can be associated with obesity development. The tool will be applicable to study of the canine obesity model and to clinical veterinarians. Results revealed eating behaviour to be similarly associated with obesity as exercise and owners giving titbits. PMID:26468435
ERIC Educational Resources Information Center
Anil, Duygu
2011-01-01
This study aims, in line with PISA (Programmes for International Students' Achievement Evaluation) 2006, at constructing a structural equation model between variables considered to be associated with 15 year old Turkish students' science achievement scores and their responses to students questionnaire. In this sense, this is a relational research…
A Structural Equation Modelling Approach for Massive Blended Synchronous Teacher Training
ERIC Educational Resources Information Center
Kannan, Kalpana; Narayanan, Krishnan
2015-01-01
This paper presents a structural equation modelling (SEM) approach for blended synchronous teacher training workshop. It examines the relationship among various factors that influence the Satisfaction (SAT) of participating teachers. Data were collected with the help of a questionnaire from about 500 engineering college teachers. These teachers…
Quantifying parsimony in structural equation modeling
Preacher, Kristopher J.
2006-01-01
Fitting propensity (FP) is defined as a model's average ability to fit diverse data patterns, all else being equal. The relevance of FP to model selection is examined in the context of structural equation modeling (SEM). In SEM it is well known...
Structural Equation Modeling in Behavioral Research
April 27, 2012 10:00 AM - 11:00 AM + Add to Outlook Calendar Date and Time: Friday, April 27th, 10:00-11:00am, EPS/7107 Lecturer: Natalia Frishman, MD PhD Candidate Iowa State University Print This Page Structural Equation Modeling in Behavioral Research News
A Brief Guide to Structural Equation Modeling
ERIC Educational Resources Information Center
Weston, Rebecca; Gore, Paul A., Jr.
2006-01-01
To complement recent articles in this journal on structural equation modeling (SEM) practice and principles by Martens and by Quintana and Maxwell, respectively, the authors offer a consumer's guide to SEM. Using an example derived from theory and research on vocational psychology, the authors outline six steps in SEM: model specification,…
Causality, Confirmation, Credulity, and Structural Equation Modeling.
ERIC Educational Resources Information Center
Biddle, Bruce J.; Marlin, Marjorie M.
1987-01-01
Defines structural equation modeling (SEM) and points out its relation to other more familiar data-analytic techniques, as well as some of the potentials and pitfalls of SEM in the analysis of developmental data. Discussion focuses on causal modeling, path diagrams, ordinary least-squares regression analysis, and powerful methods for model…
ERIC Educational Resources Information Center
Jacobs, Karen; Struyf, Elke
2013-01-01
Socioemotional guidance of students has recently become an integral part of education, however no instrument exists to measure integrated socioemotional guidance. This study therefore examines the factor structure and reliability of the Socioemotional Guidance Questionnaire. Psychometric properties of the Socioemotional Guidance Questionnaire and…
Argyrides, Marios; Kkeli, Natalie; Kendeou, Panayiota
2014-06-01
The current study aimed to confirm the factor structure and reliability of the newly translated Greek version of the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3) among 1753 Greek-Cypriot high school students. Results of the structural equation modeling indicated a very good fit with the original four-factor structure of the SATAQ-3 for both males and females. The Cronbach's alpha coefficients for the four subscales were .92 for 'Internalization-General', .82 for 'Internalization-Athlete', .94 for 'Pressure' and .88 for 'Information'. Further analyses showed no significant differences between BMI categories with respect to the Internalization-General, Internalization-Athlete and Information factors but there were significant differences on the Pressure factor. The findings of the current study support the existence of the original four-factor structure of the SATAQ-3. The validity and reliability results of the Greek version of the SATAQ-3 support its use in Greek-speaking countries or populations. PMID:24958653
Kamaruzzaman, Syahrul Nizam; Egbu, C O; Zawawi, Emma Marinie Ahmad; Karim, Saipol Bari Abd; Woon, Chen Jia
2015-05-01
It is accepted that occupants who are more satisfied with their workplace's building internal environment are more productive. The main objective of the study was to measure the occupants' level of satisfaction and the perceived importance of the design or refurbishment on office conditions. The study also attempted to determine the factors affecting the occupants' satisfaction with their building or office conditions. Post-occupancy evaluations were conducted using a structured questionnaire developed by the Built Environment Research Group at the University of Manchester, UK. Our questionnaires incorporate 22 factors relating to the internal environment and rate these in terms of "user satisfaction" and "degree of importance." The questions were modified to reflect the specific setting of the study and take into consideration the local conditions and climate in Malaysia. The overall mean satisfaction of the occupants toward their office environment was 5.35. The results were measured by a single item of overall liking of office conditions in general. Occupants were more satisfied with their state of health in the workplace, but they were extremely dissatisfied with the distance away from a window. The factor analysis divided the variables into three groups, namely intrusion, air quality, and office appearance. Structural equation modeling (SEM) was then used to determine which factor had the most significant influence on occupants' satisfaction: appearance. The findings from the study suggest that continuous improvement in aspects of the building's appearance needs to be supported with effective and comprehensive maintenance to sustain the occupants' satisfaction. PMID:25864077
Structural comparison of a translated dental attitude questionnaire: a factor analytic study.
Timmerman, E M; Hoogstraten, J; Nauta, M; Meijer, K
1996-08-01
In 1984 the Dental Attitude Questionnaire (DAQ), an instrument for assessing various aspects of a person's attitude toward oral health care, was presented by STOCKWELL & BANTING. The DAQ consists of six content scales, Cynicism, Health Concern, Motivation, Oral Function, Social Aesthetic and Susceptibility, and two validity scales, Halo and Infrequency. A Dutch translation was presented in 1986 by HOOGSTRATEN & BROERS. In order to replicate the factor analysis on the original DAQ as reported by STOCKWELL & BANTING, the present study was undertaken. The results show a change in factor structure from a three factor solution to a two factor solution. A confirmatory factor analysis shows that the original three factor structure of the DAQ is not present in the data collected with the translated version. To account for this change, some possible reasons are discussed. PMID:8871029
Generalized Ideal Gas Equations for Structureful Universe
Shahid N. Afridi; Khalid Khan
2006-09-04
We have derived generalized ideal gas equations for a structureful universe consisting of all forms of matters. We have assumed a universe that contains superclusters. Superclusters are then made of clusters. Each cluster can be further divided into smaller ones and so on. We have derived an expression for the entropy of such a universe. Our model is rather independent of the geometry of the intermediate clusters. Our calculations are valid for a non-interacting universe within non-relativistic limits. We suggest that structure formation can reduce the expansion rate of the universe.
Exploring the factor structure of the Food Cravings Questionnaire-Trait in Cuban adults
Rodríguez-Martín, Boris C.; Molerio-Pérez, Osana
2014-01-01
Food cravings refer to an intense desire to eat specific foods. The Food Cravings Questionnaire-Trait (FCQ-T) is the most commonly used instrument to assess food cravings as a multidimensional construct. Its 39 items have an underlying nine-factor structure for both the original English and Spanish version; but subsequent studies yielded fewer factors. As a result, a 15-item version of the FCQ-T with one-factor structure has been proposed (FCQ-T-reduced; see this Research Topic). The current study aimed to explore the factor structure of the Spanish version for both the FCQ-T and FCQ-T-reduced in a sample of 1241 Cuban adults. Results showed a four-factor structure for the FCQ-T, which explained 55% of the variance. Factors were highly correlated. Using the items of the FCQ-T-reduced only showed a one-factor structure, which explained 52% of the variance. Both versions of the FCQ-T were positively correlated with body mass index (BMI), scores on the Food Thoughts Suppression Inventory and weight cycling. In addition, women had higher scores than men and restrained eaters had higher scores than unrestrained eaters. To summarize, results showed that (1) the FCQ-T factor structure was significantly reduced in Cuban adults and (2) the FCQ-T-reduced may represent a good alternative to efficiently assess food craving on a trait level. PMID:24672503
COVARIANCE STRUCTURE OF PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS
Larsson, Stig
COVARIANCE STRUCTURE OF PARABOLIC STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS ANNIKA LANG, STIG LARSSON, AND CHRISTOPH SCHWAB Abstract. In this paper parabolic random partial differential equations and parabolic sto- chastic partial differential equations driven by a Wiener process are considered. A deter
Wee, Hwee-Lin; Ravens-Sieberer, Ulrike; Erhart, Michael; Li, Shu-Chuen
2007-01-01
Background Quality of life (QoL) outcomes are useful in the assessment of physical, mental and social well-being and for informed healthcare decision making. However, few studies have evaluated QoL issues among Asian children due largely to the lack of culturally valid and reliable QoL questionnaires. Hence, we aimed to report the psychometric properties, in particular factor structure, of KINDL (Singapore) questionnaires among school-going children. Methods Students aged 8–16 years from participating schools were selected by convenience sampling. Subjects self-completed KINDL-Kid (Singapore) and KINDL-Kiddo (Singapore) questionnaires, which were cross-culturally adapted from KINDL (Germany English) for use in Singapore. We evaluated floor and ceiling effects, internal consistency and performed factor analysis. Results A total of 328 respondents (mean (SD) age: 9.6 (1.31) years; 67% female; 75% Chinese, 16% Malays, 9% Indians and others) completed KINDL-Kid while 1,026 respondents (mean (SD) age: 14.0 (1.00) years; 82% female; 82% Chinese, 12% Malays; 6% Indians and others) completed KINDL-Kiddo. Mean (SD) TOTAL QoL score was 65.5 (12.76) and 56.6 (11.92) for KINDL-Kid and KINDL-Kiddo, respectively. Floor and ceiling effects were important in five of six KINDL-Kid and two of six KINDL-Kiddo subscales. Reliability coefficients ranged from 0.40 to 0.71 (KINDL-Kid) and 0.44 to 0.84 (KINDL-Kiddo). Factor analysis generated eight and seven factors in KINDL-Kid and KINDL-Kiddo, respectively. Conclusion KINDL-Kiddo exhibited good psychometric properties and may be used to assess QoL in this multi-ethnic English-speaking Asian population. However, psychometric properties of KINDL-Kid may need to be improved either by developing new items or modifying existing items. PMID:17239229
Barron, David; Swami, Viren; Towell, Tony; Hutchinson, Gerard; Morgan, Kevin D
2015-01-01
Much debate in schizotypal research has centred on the factor structure of the Schizotypal Personality Questionnaire (SPQ), with research variously showing higher-order dimensionality consisting of two to seven dimensions. In addition, cross-cultural support for the stability of those factors remains limited. Here, we examined the factor structure of the SPQ among British and Trinidadian adults. Participants from a White British subsample (n = 351) resident in the UK and from an African Caribbean subsample (n = 284) resident in Trinidad completed the SPQ. The higher-order factor structure of the SPQ was analysed through confirmatory factor analysis, followed by multiple-group analysis for the model of best fit. Between-group differences for sex and ethnicity were investigated using multivariate analysis of variance in relation to the higher-order domains. The model of best-fit was the four-factor structure, which demonstrated measurement invariance across groups. Additionally, these data had an adequate fit for two alternative models: (a) 3-factor and (b) modified 4-factor model. The British subsample had significantly higher scores across all domains than the Trinidadian group, and men scored significantly higher on the disorganised domain than women. The four-factor structure received confirmatory support and, importantly, support for use with populations varying in ethnicity and culture. PMID:25699263
2013-01-01
Background The Otitis Media-6 questionnaire (OM-6) is the most frequently used instrument to measure health related quality of life in children with otitis media. The main objectives of this study are 1) to translate and cross-culturally adapt the OM-6 into Danish, and 2) to assess important psychometric properties including structural validity and interpretability of the OM-6 in a Danish population of children suffering from otitis media. Methods The OM-6 was translated and cross-culturally adapted according to international guidelines. A longitudinal validation study enrolled 491 children and their families, and the measurement properties of the OM-6 were evaluated using the Cosmin taxonomy. The properties assessed were construct and structural validity (confirmatory factor analysis) including internal consistency, reproducibility (test-retest reliability and smallest detectable change), responsiveness and interpretability. Results A total of 435 children were eligible to participate in the study. Analyses of structural validity and internal consistency indicated that parent appraisal of hearing and speech problems may be problematic. Both scales showed similarly good test-retest reliability and construct validity, were able to discriminate between diagnostic subgroups and responsive to change. Cut-off values of 16.7 and 30.0 were found to represent minimal important change for the patients. Conclusions The Danish version of the OM-6 is a reliable, valid, responsive and interpretable questionnaire to measure quality of life in children with otitis media. This study sheds light on possible weaknesses of the instrument that needs to be acknowledged in the utilization of the instrument. However, despite these issues our results support the continuing use of OM-6 as a 1-factor functional health scale with a separate global health rating. Furthermore, indications of values representing minimal important change as perceived by the respondent are presented. PMID:24257471
Grilo, Carlos M.; Henderson, Kathryn E.; Bell, Robert L.; Crosby, Ross D.
2012-01-01
Objective The Eating Disorder Examination-Questionnaire (EDE-Q) is increasingly used in studies with bariatric surgery patients although little is known about psychometric properties of this self-report measure in this clinical group. The current study evaluated the factor structure and construct validity of the EDE-Q in bariatric surgery candidates. Methods Participants were a consecutive series of 174 obese bariatric surgery candidates who completed the EDE-Q and a battery of behavioral and psychological measures. Results Confirmatory factor analysis (CFA) revealed an inadequate fit for the original EDE-Q structure but revealed a good fit for an alternative structure suggested by recent research with obese samples. CFA supported a 7-item, 3-factor structure; the three factors were interpreted as dietary restraint, shape/weight overvaluation, and body dissatisfaction. The three factors converged with other relevant collateral measures. Conclusions These factor analytic findings, which replicate recent findings from studies with diverse obese samples, demonstrated convergent validity. Implications of these findings for clinical assessment and research with bariatric surgery patients are discussed. PMID:23229951
Model Comparison of Bayesian Semiparametric and Parametric Structural Equation Models
ERIC Educational Resources Information Center
Song, Xin-Yuan; Xia, Ye-Mao; Pan, Jun-Hao; Lee, Sik-Yum
2011-01-01
Structural equation models have wide applications. One of the most important issues in analyzing structural equation models is model comparison. This article proposes a Bayesian model comparison statistic, namely the "L[subscript nu]"-measure for both semiparametric and parametric structural equation models. For illustration purposes, we consider…
ERIC Educational Resources Information Center
Brown, Sharon L.
1994-01-01
Explored structure of brief version of Ways of Coping (WOC) Questionnaire and coping strategies employed by students enrolled in stressful academic programs. Findings from 207 veterinary medicine students lend support to view that there are relatively stable underlying coping structures across samples or groups within specified coping situations.…
AN ATMOSPHERIC STRUCTURE EQUATION FOR GRAIN GROWTH
Ormel, C.W.
2014-07-01
We present a method to include the evolution of the grain size and grain opacity ?{sub gr} in the equations describing the structure of protoplanetary atmospheres. The key assumption of this method is that a single grain size dominates the grain size distribution at any height r. In addition to following grain growth, the method accounts for mass deposition by planetesimals and grain porosity. We illustrate this method by computation of a simplified atmosphere structure model. In agreement with previous works, grain coagulation is seen to be very efficient. The opacity drops to values much below the often-used ''interstellar medium opacities'' (?1 cm{sup 2} g{sup –1}) and the atmosphere structure profiles for temperature and density resemble that of the grain-free case. Deposition of planetesimals in the radiative part of the atmosphere hardly influences this outcome as the added surface is quickly coagulated away. We observe a modest dependence on the internal structure (porosity), but show that filling factors cannot become too large because of compression by gas drag.
Fournier, Jay C.; DeRubeis, Robert J.; Beck, Aaron T.
2013-01-01
Background This study examines the structure of the Personality Belief Questionnaire (PBQ), a self-report instrument designed to assess dysfunctional beliefs associated with personality pathology, as proposed by the cognitive theory of personality dysfunction. Methods The PBQ was examined using exploratory factor analysis with responses from 438 depressed outpatients, and confirmatory factor analysis with responses from 683 treatment-seeking psychiatric outpatients. All participants were assessed for personality disorder using a standard clinical interview. The validity of the resulting factor structure was assessed in the combined sample (N=1121) by examining PBQ scores for patients with and without personality disorder diagnoses. Results Exploratory and confirmatory analyses converged to indicate that the PBQ is best described by 7 empirically identified factors: 6 assess dysfunctional beliefs associated with forms of personality pathology recognized in DSM-IV. Validity analyses revealed that those diagnosed with a personality disorder evidenced a higher average score on all factors, relative to those without these disorders. Subsets of patients diagnosed with specific DSM-IV personality disorders scored higher, on average, on the factor associated with their respective diagnosis, relative to all other factors. Conclusions The pattern of results has implications for the conceptualization of personality pathology. To our knowledge, no formal diagnostic or assessment system has yet systematically incorporated the role of dysfunctional beliefs into its description of personality pathology. The identification of dysfunctional beliefs may not only aid in case conceptualization, but may provide unique targets for psychological treatment. Recommendations for future personality pathology assessment systems are provided. PMID:21910933
Factor structure of the Parent Emotional Reaction Questionnaire: analysis and validation
Holt, Tonje; Cohen, Judith A.; Mannarino, Anthony
2015-01-01
Background Although many children experience violence and abuse each year, there is a lack of instruments measuring parents’ emotional reactions to these events. One instrument, the Parent Emotional Reaction Questionnaire (PERQ), allows researchers and clinicians to survey a broad spectrum of parents’ feelings directly related to their children's traumatic experiences. The objectives of this study were: (1) to examine the factor structure and the internal consistency of the PERQ; (2) to evaluate the discriminant validity of the instrument; and (3) to measure whether potential subscales are sensitive to change. Method A Norwegian sample of 120 primary caregivers of a clinical sample of 120 traumatized children and youths (M age=14.7, SD=2.2; 79.8% girls) were asked to report their emotional reactions to their child's self-reported worst trauma. Exploratory factor analysis was used to explore the underlying factor structure of the data. Results The analysis of the PERQ showed a three-factor structure, conceptualized as PERQdistress, PERQshame, and PERQguilt. The internal consistencies of all three subscales were satisfactory. The correlations between the PERQ subscales and two other parental measurements revealed small to moderate effect sizes, supporting the discriminant validity of the PERQ subscales. The differences in sum scores of the PERQ subscales before and after a therapeutic intervention suggest that all of the subscales were sensitive to change. Conclusions Study findings support the validity of conceptualizing the PERQ as three separate subscales that capture clinically meaningful features of parents’ feelings after their children have experienced trauma. However, the subscales need to be further evaluated using a larger sample size and a confirmatory factor analytic approach. PMID:26333541
Structural equation modeling: strengths, limitations, and misconceptions.
Tomarken, Andrew J; Waller, Niels G
2005-01-01
Because structural equation modeling (SEM) has become a very popular data-analytic technique, it is important for clinical scientists to have a balanced perception of its strengths and limitations. We review several strengths of SEM, with a particular focus on recent innovations (e.g., latent growth modeling, multilevel SEM models, and approaches for dealing with missing data and with violations of normality assumptions) that underscore how SEM has become a broad data-analytic framework with flexible and unique capabilities. We also consider several limitations of SEM and some misconceptions that it tends to elicit. Major themes emphasized are the problem of omitted variables, the importance of lower-order model components, potential limitations of models judged to be well fitting, the inaccuracy of some commonly used rules of thumb, and the importance of study design. Throughout, we offer recommendations for the conduct of SEM analyses and the reporting of results. PMID:17716081
Ruiz-Párraga, Gema T; López-Martínez, Alicia E; Rusu, Adina C; Hasenbring, Monika I
2015-01-01
To analyze the factorial structure and psychometric properties of the Spanish adaptation of the AEQ, and to validate it by reporting relevant pain-related variables, which were not investigated in the original study. One hundred and fifty Spanish patients diagnosed with chronic back and neck pain were referred by physicians from different pain clinics in Spain; all the patients filled out the questionnaires at their clinic. A series of principal components analyses (PCA) was performed to develop the Spanish version of the AEQ. Reliability and validity were also calculated. The PCAs revealed five fear-avoidance scales (Kaiser-Meyer-Olkin measures were between .60 and .88, and Bartlett's tests were significant, p .73) and suitable validity (p < .05). New results associated with pain-related cognitive/affective and behavioural responses are discussed. This instrument will probably help clinicians to identify Spanish patients at a high risk of chronicity and to develop treatments tailored to the different profiles in order to improve secondary and tertiary prevention in back and neck pain. PMID:26585121
Chen, Liuxi; Xu, Kai; Fu, Lingyun; Xu, Shaofang; Gao, Qianqian; Wang, Wei
2015-01-01
Consistent results have shown a relationship between the psychological world of children and their perceived parental bonding or family attachment style, but to date there is no single measure covering both styles. The authors designed a statement matrix with 116 items for this purpose and compared it with the Parental Bonding Instrument (PBI) in a study with 718 university students. After exploratory and confirmatory factor analyses, five factors (scales)--namely, Paternal/Maternal Encouragement (5 items each), Paternal/Maternal Abuse (5 items each), Paternal/Maternal Freedom Release (5 items each), General Attachment (5 items), and Paternal/Maternal Dominance (4 items each)--were defined to form a Family Relationship Questionnaire (FRQ). The internal alphas of the factors ranged from .64 to .83, and their congruency coefficients were .93 to .98 in samples regarding father and mother. Women scored significantly higher on FRQ General Attachment and Maternal Encouragement and lower on Paternal Abuse than men did; only children scored significantly higher on Paternal and Maternal Encouragements than children with siblings did. Women also scored significantly higher on PBI Paternal Autonomy Denial; only children scored significantly higher on Paternal and Maternal Cares and Maternal Autonomy Denial. All intercorrelations between FRQ scales were low to medium, and some correlations between FRQ and PBI scales were medium to high. This study demonstrates that the FRQ has a structure of five factors with satisfactory discriminant and convergent validities, which might help to characterize family relationships in healthy and clinical populations. PMID:26366981
ERIC Educational Resources Information Center
Chiu, Chung-Yi; Jochman, Joseph; Fujikawa, Mayu; Strand, David; Cheing, Gladys; Lee, Gloria; Chan, Fong
2014-01-01
Purpose: To examine the factorial structure of the "Coping Strategy Questionnaire"-24 (CSQ-24) in a sample of Canadians with chronic musculoskeletal pain. Method: The sample included 171 workers' compensation clients (50.9% men) recruited from outpatient rehabilitation facilities in Canada. Mean age of participants was 42.45 years…
ERIC Educational Resources Information Center
Thombs, Brett D.; Bernstein, David P.; Lobbestael, Jill; Arntz, Arnoud
2009-01-01
Objective: The 28-item Childhood Trauma Questionnaire-Short Form (CTQ-SF) has been translated into at least 10 different languages. The validity of translated versions of the CTQ-SF, however, has generally not been examined. The objective of this study was to investigate the factor structure, internal consistency reliability, and known-groups…
ERIC Educational Resources Information Center
He, Jian-Ping; Burstein, Marcy; Schmitz, Anja; Merikangas, Kathleen R.
2013-01-01
The Strengths and Difficulties Questionnaire (SDQ) is one of the most commonly used instruments for screening psychopathology in children and adolescents. This study evaluated the hypothesized five-factor structure of the SDQ and examined its convergent validity against comprehensive clinical diagnostic assessments. Data were derived from the…
Sensitivity Equations for a Size-Structured Population Model
-structured population models. The growth and mortality rates of the shrimp population are affected by severalSensitivity Equations for a Size-Structured Population Model H. T. Banks, Stacey L. Ernstberger-structured population model and derive sensitivity partial differential equations for the sensitivities of solutions
Atomic Structure Schrdinger equation has approximate solutions for multi-
Zakarian, Armen
Atomic Structure Schrödinger equation has approximate solutions for multi- electron atoms, which indicate that all atoms are like hydrogen Atomic Structure Schrödinger equation has approximate solutions 3s 3p 3d Energy hydrogen multi-electron #12;Atomic Structure · orbitals are populated by electrons
... Ask Brochures and Resources Videos AANA / Patients Pre-Anesthesia Questionnaire Page Content The information you supply below ... supplements; complementary or alternative medicines)______________________________________________________ _______________________________________________________________ Prior ... Pre-Anesthesia Questionnaire Please answer the following questions. These responses ...
A Structural Equation Modeling Analysis of Influences on Juvenile Delinquency
ERIC Educational Resources Information Center
Barrett, David E.; Katsiyannis, Antonis; Zhang, Dalun; Zhang, Dake
2014-01-01
This study examined influences on delinquency and recidivism using structural equation modeling. The sample comprised 199,204 individuals: 99,602 youth whose cases had been processed by the South Carolina Department of Juvenile Justice and a matched control group of 99,602 youth without juvenile records. Structural equation modeling for the…
Fitting ARMA Time Series by Structural Equation Models.
ERIC Educational Resources Information Center
van Buuren, Stef
1997-01-01
This paper outlines how the stationary ARMA (p,q) model (G. Box and G. Jenkins, 1976) can be specified as a structural equation model. Maximum likelihood estimates for the parameters in the ARMA model can be obtained by software for fitting structural equation models. The method is applied to three problem types. (SLD)
ERIC Educational Resources Information Center
Bjornsdottir, Gyda; Halldorsson, Jonas G.; Steinberg, Stacy; Hansdottir, Ingunn; Kristjansson, Kristleifur; Stefansson, Hreinn; Stefansson, Kari
2014-01-01
This article describes psychometric testing of an Icelandic adaptation of the "Adult Reading History Questionnaire" (ARHQ), designed to detect a history of reading difficulties indicative of dyslexia. Tested in a large and diverse sample of 2,187 adults, the Icelandic adaptation demonstrated internal consistency reliability…
ERIC Educational Resources Information Center
Paivio, Sandra, C.; Cramer, Kenneth, M.
2004-01-01
Objective: The aims of this study were to examine (1) the psychometric properties of the Childhood Trauma Questionnaire [CTQ; Bernstein, D., Fink, L., Handelsman, L., Foote, J., Lovejoy, M., Wenzel, K., Sapareto, E., & Ruggiero, J. (1994). Initial reliability and validity of a new retrospective measure of child abuse and neglect. American Journal…
The Home Situations Questionnaire-PDD Version: Factor Structure and Psychometric Properties
ERIC Educational Resources Information Center
Chowdhury, M.; Aman, M. G.; Scahill, L.; Swiezy, N.; Arnold, L. E.; Lecavalier, L.; Johnson, C.; Handen, B.; Stigler, K.; Bearss, K.; Sukhodolsky, D.; McDougle, C. J.
2010-01-01
Background: The Home Situations Questionnaire (HSQ) is a caregiver-rated scale designed to assess behavioural non-compliance in everyday settings that has been used in several studies in typically developing children. Currently there is no accepted measure of behavioural non-compliance in children with pervasive developmental disorders (PDDs).…
Component Structure, Reliability, and Stability of Lawrence's Self-Esteem Questionnaire (LAWSEQ)
ERIC Educational Resources Information Center
Rae, Gordon; Dalto, Georgia; Loughrey, Dolores; Woods, Caroline
2011-01-01
Lawrence's Self-Esteem Questionnaire (LAWSEQ) was administered to 120 Year 1 pupils in six schools in Belfast, Northern Ireland. A principal components analysis indicated that the scale items were unidimensional and that the reliability of the scores, as estimated by Cronbach's alpha, was satisfactory ([alpha] = 0.73). There were no differences…
Sensitivity of rocky planet structures to the equation of state
Swift, D C
2009-06-10
Structures were calculated for Mercury, Venus, Earth, the Moon, and Mars, using a core-mantle model and adjusting the core radius to reproduce the observed mass and diameter of each body. Structures were calculated using Fe and basalt equations of state of different degrees of sophistication for the core and mantle. The choice of equation of state had a significant effect on the inferred structure. For each structure, the moment of inertia ratio was calculated and compared with observed values. Linear Grueneisen equations of state fitted to limited portions of shock data reproduced the observed moments of inertia significantly better than did more detailed equations of state incorporating phase transitions, presumably reflecting the actual compositions of the bodies. The linear Grueneisen equations of state and corresponding structures seem however to be a reasonable starting point for comparative simulations of large-scale astrophysical impacts.
New Formulation of the Governing Equations for Analyzing Outrigger Structures
Er, G.-K.
2010-05-21
In this paper, an easily comprehensible solution procedure is proposed for the analysis of outrigger-braced structures. The idea is based on the compatibility of the columns' axial deformation. The unknowns are selected to be the axial forces in the columns. The resulted governing equations and the equations for the optimum analysis of the outrigger locations are different from the conventional ones, but numerical analysis shows that the results obtained with the new equations are same as those obtained with conventional equations. The relations between the new equations and the conventional ones are also figured out. The new procedure of formulating the governing equations can be easily extended to more complicated cases of outrigger-braced structures.
Structured Multi-Matrix Variate, Matrix Polynomial Equations: Solution Techniques
Garimella Rama Murthy
2012-07-21
In this research paper, structured bi-matrix variate, matrix quadratic equations are considered. Some lemmas related to determining the eigenvalues of unknown matrices are proved. Also, a method of determining the diagonalizabe unknown matrices is provided. The results are generalized to multi-matrix variate, matrix polynomial equations. Briefly generalization to tensor variate polynomial equations is discussed. It is hoped that the results lead to important contributions in "non-commutative algebra".
Hamiltonian structures for the Ostrovsky-Vakhnenko equation
NASA Astrophysics Data System (ADS)
Brunelli, J. C.; Sakovich, S.
2013-01-01
We obtain a bi-Hamiltonian formulation for the Ostrovsky-Vakhnenko (OV) equation using its higher order symmetry and a new transformation to the Caudrey-Dodd-Gibbon-Sawada-Kotera equation. Central to this derivation is the relation between Hamiltonian structures when dependent and independent variables are transformed.
The relativistic equations of stellar structure and evolution
NASA Technical Reports Server (NTRS)
Thorne, K. S.
1977-01-01
The general-relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general-relativistic version of the mixing-length formalism for convection is presented.
Case Residuals in Structural Equation Modeling
ERIC Educational Resources Information Center
Cardinale, John
2011-01-01
From the beginning, lead methodologists in psychometrics and quantitative psychology have been well aware of the problems of fitting structural and confirmatory factor models. The question we approach in our research is how to best detect this misfit and how to identify specific sources of misfit by scrutinizing the data at the case level. Since…
Reporting Results from Structural Equation Modeling Analyses in Archives of Scientific Psychology
Hoyle, Rick H.; Isherwood, Jennifer C.
2013-01-01
Psychological research typically involves the analysis of data (e.g., questionnaire responses, records of behavior) using statistical methods. The description of how those methods are used and the results they produce is a key component of scholarly publications. Despite their importance, these descriptions are not always complete and clear. In order to ensure the completeness and clarity of these descriptions, the Archives of Scientific Psychology requires that authors of manuscripts to be considered for publication adhere to a set of publication standards. Although the current standards cover most of the statistical methods commonly used in psychological research, they do not cover them all. In this manuscript, we propose adjustments to the current standards and the addition of additional standards for a statistical method not adequately covered in the current standards—structural equation modeling (SEM). Adherence to the standards we propose would ensure that scholarly publications that report results of data analyzed using SEM are complete and clear. Scientific Abstract We recommend reporting standards consistent with the Journal Article Reporting Standards (JARS) of the American Psychological Association for manuscripts in which results from structural equation modeling (SEM) analyses are presented. For all sections of the general JARS except the results section, we recommend minor adjustments. For the results section of the JARS, we provide a supplemental module specific to reports of research that use SEM. The result is a questionnaire that ensures thorough and detailed reports of SEM analyses in the Archives. PMID:23997997
Bayesian Semiparametric Structural Equation Models with Latent Variables
ERIC Educational Resources Information Center
Yang, Mingan; Dunson, David B.
2010-01-01
Structural equation models (SEMs) with latent variables are widely useful for sparse covariance structure modeling and for inferring relationships among latent variables. Bayesian SEMs are appealing in allowing for the incorporation of prior information and in providing exact posterior distributions of unknowns, including the latent variables. In…
Cecchini, Jose A.; Fernández-Rio, Javier; Méndez-Giménez, Antonio
2015-01-01
This study explored the relationships between athletes’ competence self-perceptions and metaperceptions. Two hundred and fifty one student-athletes (14.26 ± 1.89 years), members of twenty different teams (basketball, soccer) completed a questionnaire which included the Perception of Success Questionnaire, the Competence subscale of the Intrinsic Motivation Inventory, and modified versions of both questionnaires to assess athletes’ metaperceptions. Structural equation modelling analysis revealed that athletes’ task and ego metaperceptions positively predicted task and ego self-perceptions, respectively. Competence metaperceptions were strong predictors of competence self-perceptions, confirming the atypical metaperception formation in outcome-dependent contexts such as sport. Task and ego metaperceptions positively predicted athletes’ competence metaperceptions. How coaches value their athletes’ competence is more influential on what the athletes think of themselves than their own self-perceptions. Athletes’ ego and task metaperceptions influenced their competence metaperceptions (how coaches rate their competence). Therefore, athletes build their competence metaperceptions using all information available from their coaches. Finally, only task-self perfections positively predicted athletes’ competence self-perceptions. PMID:26240662
He, Jian-Ping; Burstein, Marcy; Schmitz, Anja; Merikangas, Kathleen R
2013-05-01
The Strengths and Difficulties Questionnaire (SDQ) is one of the most commonly used instruments for screening psychopathology in children and adolescents. This study evaluated the hypothesized five-factor structure of the SDQ and examined its convergent validity against comprehensive clinical diagnostic assessments. Data were derived from the National Comorbidity Survey - Adolescent Supplement (NCS-A), a nationally representative sample of U.S. adolescents aged 13 to 18 years. Parents/parent surrogates (n=6,483) was asked to complete a self-administered questionnaire including the SDQ and DSM-IV comprehensive diagnostic information on the participating adolescents. Confirmatory factor analysis (CFA) was conducted to assess the factor structure of the SDQ. The five-factor solution of the SDQ (including emotional, conduct, hyperactivity-inattention, peer relationship, and prosocial) provided a satisfactory fit to the data, and was invariant across sex, age, race/ethnicity and income subgroups. SDQ scores predicted a significantly increased probability of meeting criteria for a DSM-IV disorder, with better prediction for behavior disorders than for mood disorders. Decreasing the SDQ cutoffs to the 80th percentile significantly increased the sensitivity from 39% to 63% for the SDQ Total Difficulties Score, with an expected decrease in specificity from 93% to 87%. This work confirms the five-factor structure of the SDQ in an ethnically and sociodemogrpahically diverse community sample of adolescents. Our findings strengthen empirical evidence for the use of the parent-reported SDQ as a screening tool for DSM-IV behavioral and emotional disorders in adolescents identified in the general population. PMID:23183936
From Questionnaire to Conversation: A Structural Intervention to Improve HIV Test Counseling
Sheon, Nicolas; Lee, Seung-Hee; Facente, Shelley
2010-01-01
Objectives We describe the effects of structural intervention to enhance the quality of HIV test counseling interaction with men who have sex with men (MSM) in San Francisco. Methods Audio recordings of 28 rapid HIV test sessions by seven counselors were collected in two phases: before and after implementation of a waiting room intervention prior to the session. The sessions were analyzed using sequence maps to visualize and compare the sequence and distribution of four activities: counseling, information delivery, data collection, and sample collection. Results Prior to the intervention, counselors and clients often oriented to data collection about the client’s past risk as if it were a survey. In sessions recorded after the intervention, questions about past risk were dispersed throughout the session and embedded within an elaborated discussion of the client’s particular life circumstances. Conclusion Direct observation with the aid of sequence maps illuminates the ways that counselors and clients collaboratively orient to various tasks. Practice Implications We demonstrated the feasibility of a structural intervention that improved the quality of both counseling and the accuracy of client risk data without requiring additional session time or counselor training. PMID:20888723
Killing-Yano equations and G-structures
G. Papadopoulos
2008-04-28
We solve the Killing-Yano equation on manifolds with a $G$-structure for $G=SO(n), U(n), SU(n), Sp(n)\\cdot Sp(1), Sp(n), G_2$ and $Spin(7)$. Solutions include nearly-K\\"ahler, weak holonomy $G_2$, balanced SU(n) and holonomy $G$ manifolds. As an application, we find that particle probes on $AdS_4\\times X$ compactifications of type IIA and 11-dimensional supergravity admit a ${\\cal W}$-type of symmetry generated by the fundamental forms. We also explore the ${\\cal W}$-symmetries of string and particle actions in heterotic and common sector supersymmetric backgrounds. In the heterotic case, the generators of the ${\\cal W}$-symmetries completely characterize the solutions of the gravitino Killing spinor equation, and the structure constants of the ${\\cal W}$-symmetry algebra depend on the solution of the dilatino Killing spinor equation.
Tests for Stability in Linear Structural Equation Systems.
ERIC Educational Resources Information Center
Bentler, P. N.; Freeman, Edward H.
1983-01-01
Interpretations regarding the effects of exogenous and endogenous variables on endogenous variables in linear structural equation systems depend upon the convergence of a matrix power series. The test for convergence developed by Joreskog and Sorbom is shown to be only sufficient, not necessary and sufficient. (Author/JKS)
A Structural Equation Model for Predicting Business Student Performance
ERIC Educational Resources Information Center
Pomykalski, James J.; Dion, Paul; Brock, James L.
2008-01-01
In this study, the authors developed a structural equation model that accounted for 79% of the variability of a student's final grade point average by using a sample size of 147 students. The model is based on student grades in 4 foundational business courses: introduction to business, macroeconomics, statistics, and using databases. Educators and…
Structural Equation Modeling Diagnostics Using R Package Semdiag and EQS
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Zhang, Zhiyong
2012-01-01
Yuan and Hayashi (2010) introduced 2 scatter plots for model and data diagnostics in structural equation modeling (SEM). However, the generation of the plots requires in-depth understanding of their underlying technical details. This article develops and introduces an R package semdiag for easily drawing the 2 plots. With a model specified in EQS…
Bayesian Data-Model Fit Assessment for Structural Equation Modeling
ERIC Educational Resources Information Center
Levy, Roy
2011-01-01
Bayesian approaches to modeling are receiving an increasing amount of attention in the areas of model construction and estimation in factor analysis, structural equation modeling (SEM), and related latent variable models. However, model diagnostics and model criticism remain relatively understudied aspects of Bayesian SEM. This article describes…
Structural Equations and Causal Explanations: Some Challenges for Causal SEM
ERIC Educational Resources Information Center
Markus, Keith A.
2010-01-01
One common application of structural equation modeling (SEM) involves expressing and empirically investigating causal explanations. Nonetheless, several aspects of causal explanation that have an impact on behavioral science methodology remain poorly understood. It remains unclear whether applications of SEM should attempt to provide complete…
Implementing Restricted Maximum Likelihood Estimation in Structural Equation Models
ERIC Educational Resources Information Center
Cheung, Mike W.-L.
2013-01-01
Structural equation modeling (SEM) is now a generic modeling framework for many multivariate techniques applied in the social and behavioral sciences. Many statistical models can be considered either as special cases of SEM or as part of the latent variable modeling framework. One popular extension is the use of SEM to conduct linear mixed-effects…
Asymptotic Biases in Exploratory Factor Analysis and Structural Equation Modeling
ERIC Educational Resources Information Center
Ogasawara, Haruhiko
2004-01-01
Formulas for the asymptotic biases of the parameter estimates in structural equation models are provided in the case of the Wishart maximum likelihood estimation for normally and nonnormally distributed variables. When multivariate normality is satisfied, considerable simplification is obtained for the models of unstandardized variables. Formulas…
A Structural Equation Model of Conceptual Change in Physics
ERIC Educational Resources Information Center
Taasoobshirazi, Gita; Sinatra, Gale M.
2011-01-01
A model of conceptual change in physics was tested on introductory-level, college physics students. Structural equation modeling was used to test hypothesized relationships among variables linked to conceptual change in physics including an approach goal orientation, need for cognition, motivation, and course grade. Conceptual change in physics…
Habitat fragmentation and reproductive success: a structural equation modelling approach
Helle, Samuli
Habitat fragmentation and reproductive success: a structural equation modelling approach Eric Le on the effects of habitat fragmentation, whereby habitat is lost and the spatial configuration of remaining habitat patches is altered, on individual breeding per- formance. However, we still lack consensus of how
A Bayesian Approach for Analyzing Longitudinal Structural Equation Models
ERIC Educational Resources Information Center
Song, Xin-Yuan; Lu, Zhao-Hua; Hser, Yih-Ing; Lee, Sik-Yum
2011-01-01
This article considers a Bayesian approach for analyzing a longitudinal 2-level nonlinear structural equation model with covariates, and mixed continuous and ordered categorical variables. The first-level model is formulated for measures taken at each time point nested within individuals for investigating their characteristics that are dynamically…
Using Fixed Thresholds with Grouped Data in Structural Equation Modeling
ERIC Educational Resources Information Center
Koran, Jennifer; Hancock, Gregory R.
2010-01-01
Valuable methods have been developed for incorporating ordinal variables into structural equation models using a latent response variable formulation. However, some model parameters, such as the means and variances of latent factors, can be quite difficult to interpret because the latent response variables have an arbitrary metric. This limitation…
Multilevel Analysis of Structural Equation Models via the EM Algorithm.
ERIC Educational Resources Information Center
Jo, See-Heyon
The question of how to analyze unbalanced hierarchical data generated from structural equation models has been a common problem for researchers and analysts. Among difficulties plaguing statistical modeling are estimation bias due to measurement error and the estimation of the effects of the individual's hierarchical social milieu. This paper…
Multiple Imputation Strategies for Multiple Group Structural Equation Models
ERIC Educational Resources Information Center
Enders, Craig K.; Gottschall, Amanda C.
2011-01-01
Although structural equation modeling software packages use maximum likelihood estimation by default, there are situations where one might prefer to use multiple imputation to handle missing data rather than maximum likelihood estimation (e.g., when incorporating auxiliary variables). The selection of variables is one of the nuances associated…
Latent Growth Curves within Developmental Structural Equation Models.
ERIC Educational Resources Information Center
McArdle, J. J.; Epstein, David
1987-01-01
Uses structural equation modeling to combine traditional ideas from repeated-measures ANOVA with some traditional ideas from longitudinal factor analysis. The model describes a latent growth curve model that permits the estimation of parameters representing individual and group dynamics. (Author/RH)
The relativistic equations of stellar structure and evolution
NASA Technical Reports Server (NTRS)
Thorne, K. S.
1975-01-01
The general relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. A general relativistic version of the mixing-length formalism for convection is presented. It is argued that in work on spherical systems, general relativity theorists have identified the wrong quantity as total mass-energy inside radius r.
ERIC Educational Resources Information Center
Makikangas, Anne; Feldt, Taru; Kinnunen, Ulla; Tolvanen, Asko; Kinnunen, Marja-Liisa; Pulkkinen, Lea
2006-01-01
This study provides new knowledge about the factor structure of the 12-item General Health Questionnaire (GHQ-12; D. Goldberg, 1972) through the application of confirmatory factor analysis to longitudinal data, thereby enabling investigation of the factor structure, its invariance across time, and the rank-order stability of the factors. Two…
Rönnlund, Michael; Vestergren, Peter; Stenling, Andreas; Nilsson, Lars-Göran; Bergdahl, Maud; Bergdahl, Jan
2015-10-01
We investigated the factorial structure of the Perceived Stress Questionnaire (PSQ-recent; Levenstein, Prantera, Varvo et al., 1993) in a large (N = 1516; 35-95 years) population-based Swedish sample (Nilsson, Adolfsson, Bäckman et al., 2004; Nilsson, Bäckman, Erngrund et al., 1997). Exploratory principal components analysis (PCA) was conducted on a first, randomly drawn subsample (n = 506). Next, the model based on the PCA was tested in a second sample (n = 505). Finally, a third sample (n = 505) was used to cross-validate the model. Five components were extracted in the PCA (eigenvalue > 1) and labeled "Demands," "Worries/Tension," "Lack of joy," "Conflict," and "Fatigue," respectively. Twenty-one out of the 30 original PSQ items were retained in a confirmatory factor analysis (CFA) model that included the five (first-order) factors and, additionally, a general (second-order) stress factor, not considered in prior models. The model showed reasonable goodness of fit [?(2)(184) = 511.2, p < 0.001; CFI = 0.904; RMSEA = 0.059; and SRMR = 0.063]. Multigroup confirmatory factor analyses supported the validity of the established model. The results are discussed in relation to prior investigations of the factorial structure of the PSQ. PMID:26096909
Multidisciplinary optimization of controlled space structures with global sensitivity equations
NASA Technical Reports Server (NTRS)
Padula, Sharon L.; James, Benjamin B.; Graves, Philip C.; Woodard, Stanley E.
1991-01-01
A new method for the preliminary design of controlled space structures is presented. The method coordinates standard finite element structural analysis, multivariable controls, and nonlinear programming codes and allows simultaneous optimization of the structures and control systems of a spacecraft. Global sensitivity equations are a key feature of this method. The preliminary design of a generic geostationary platform is used to demonstrate the multidisciplinary optimization method. Fifteen design variables are used to optimize truss member sizes and feedback gain values. The goal is to reduce the total mass of the structure and the vibration control system while satisfying constraints on vibration decay rate. Incorporating the nonnegligible mass of actuators causes an essential coupling between structural design variables and control design variables. The solution of the demonstration problem is an important step toward a comprehensive preliminary design capability for structures and control systems. Use of global sensitivity equations helps solve optimization problems that have a large number of design variables and a high degree of coupling between disciplines.
Extended Navier-Stokes equations, ultrasonic absorption and shock structure
NASA Astrophysics Data System (ADS)
Emanuel, G.
2015-01-01
The Navier-Stokes (N-S) equations for a steady or unsteady, compressible, continuum flow are modified. The extension is based on a Stokesian fluid with a single nonlinear term in an isotropic stress, rate-of-deformation relation. This is the simplest possible nonlinear extension that also satisfies the second law of thermodynamics. The transport coefficient of this term is referred to as the third viscosity coefficient. In the extended version, the momentum and energy equations each contain a nonlinear term that is proportional to this new coefficient. These terms are significant only when the velocity gradient is extremely large. They are inconsequential, e.g., in a laminar boundary layer. Nevertheless, there are flows where the extended version of the N-S equations is relevant. The first of these is an ultrasonic, unsteady, one-dimensional flow, which is used for evaluating the bulk viscosity. In this case, the linearized N-S equations become singular as the ultrasonic frequency increases toward infinity. When the frequency is sufficiently large, nonlinear terms in the extended N-S equations need to be retained. The terms that are proportional to the third viscosity coefficient increase in importance, relative to linear terms, as the fourth power of the frequency. A second example is shock wave structure. A model is established and numerically solved for the normalized density derivative. Results are compared with corresponding measurements for argon when the upstream Mach number is 1.058 and 1.23. Good agreement between the extended N-S predictions and measurements is obtained for both Mach numbers with a single, but extremely small, value for the third viscosity coefficient. An important difference between conventional and extended N-S shock structure solutions is that the extended-model solution depends on the upstream pressure, whereas the conventional solution does not.
ERIC Educational Resources Information Center
Crede, Marcus; Niehorster, Sarah
2012-01-01
This paper presents a meta-analytic review (k = 237, N = 44,668) of the adjustment to college literature. The review, based on studies using the Student Adaptation to College Questionnaire, is organized around three primary themes: (1) the structure of students' adjustment to college, (2) the relationship of adjustment to college constructs with…
ERIC Educational Resources Information Center
Uz Bas, Asli; Yurdabakan, Irfan
2012-01-01
The present study aimed to evaluate the factor structure of the Reactive-Proactive Aggression Questionnaire (RPQ) with Turkish children, and to investigate gender, grade-level, and socioeconomic status (SES) differences in reactive and proactive aggression. Participants consisted of 1,081 Turkish children (544 boys and 537 girls) aged 9 to 14…
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; Byun, Chansup
1993-01-01
A computational procedure is presented to study fluid-structural interaction problems for three-dimensional aerospace structures. The flow is modeled using the three-dimensional unsteady Euler/Navier-Stokes equations and solved using the finite-difference approach. The three dimensional structure is modeled using shell/plate finite-element formulation. The two disciplines are coupled using a domain decomposition approach. Accurate procedures both in time and space are developed to combine the solutions from the flow equations with those of the structural equations. Time accuracy is maintained using aeroelastic configuration-adaptive moving grids that are computed every time step. The work done by aerodynamic forces due to structural deformations is preserved using consistent loads. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Results are illustrated for a typical wing-body configuration.
Crystal structure optimisation using an auxiliary equation of state
NASA Astrophysics Data System (ADS)
Jackson, Adam J.; Skelton, Jonathan M.; Hendon, Christopher H.; Butler, Keith T.; Walsh, Aron
2015-11-01
Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy-volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular, for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other "beyond" density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS, and ZnTe using nine density functionals and applied to the quaternary semiconductor Cu2ZnSnS4 and the magnetic metal-organic framework HKUST-1.
Crystal structure optimisation using an auxiliary equation of state.
Jackson, Adam J; Skelton, Jonathan M; Hendon, Christopher H; Butler, Keith T; Walsh, Aron
2015-11-14
Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy-volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular, for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other "beyond" density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS, and ZnTe using nine density functionals and applied to the quaternary semiconductor Cu2ZnSnS4 and the magnetic metal-organic framework HKUST-1. PMID:26567640
Model fit evaluation in multilevel structural equation models
Ryu, Ehri
2014-01-01
Assessing goodness of model fit is one of the key questions in structural equation modeling (SEM). Goodness of fit is the extent to which the hypothesized model reproduces the multivariate structure underlying the set of variables. During the earlier development of multilevel structural equation models, the “standard” approach was to evaluate the goodness of fit for the entire model across all levels simultaneously. The model fit statistics produced by the standard approach have a potential problem in detecting lack of fit in the higher-level model for which the effective sample size is much smaller. Also when the standard approach results in poor model fit, it is not clear at which level the model does not fit well. This article reviews two alternative approaches that have been proposed to overcome the limitations of the standard approach. One is a two-step procedure which first produces estimates of saturated covariance matrices at each level and then performs single-level analysis at each level with the estimated covariance matrices as input (Yuan and Bentler, 2007). The other level-specific approach utilizes partially saturated models to obtain test statistics and fit indices for each level separately (Ryu and West, 2009). Simulation studies (e.g., Yuan and Bentler, 2007; Ryu and West, 2009) have consistently shown that both alternative approaches performed well in detecting lack of fit at any level, whereas the standard approach failed to detect lack of fit at the higher level. It is recommended that the alternative approaches are used to assess the model fit in multilevel structural equation model. Advantages and disadvantages of the two alternative approaches are discussed. The alternative approaches are demonstrated in an empirical example. PMID:24550882
ERIC Educational Resources Information Center
Sanne, Bjarte; Torsheim, Torbjorn; Heiervang, Einar; Stormark, Kjell Morten
2009-01-01
Objective: To test Goodman's theoretical 5-factor model of the Strengths and Difficulties Questionnaire (SDQ) in an analysis of the Norwegian parent (P) and teacher (T) versions of the questionnaire. Method: The T-SDQ was analyzed for 8,999 (95.4% of all) children in primary school grades 2-4 in Bergen, Norway, whereas the P-SDQ was examined for…
Mixed effects structural equation models and phenotypic causal networks.
Valente, Bruno Dourado; de Magalhães Rosa, Guilherme Jordão
2013-01-01
Complex networks with causal relationships among variables are pervasive in biology. Their study, however, requires special modeling approaches. Structural equation models (SEM) allow the representation of causal mechanisms among phenotypic traits and inferring the magnitude of causal relationships. This information is important not only in understanding how variables relate to each other in a biological system, but also to predict how this system reacts under external interventions which are common in fields related to health and food production. Nevertheless, fitting a SEM requires defining a priori the causal structure among traits, which is the qualitative information that describes how traits are causally related to each other. Here, we present directions for the applications of SEM to investigate a system of phenotypic traits after searching for causal structures among them. The search may be performed under confounding effects exerted by genetic correlations. PMID:23756905
A New Look at the Big Five Factor Structure through Exploratory Structural Equation Modeling
ERIC Educational Resources Information Center
Marsh, Herbert W.; Ludtke, Oliver; Muthen, Bengt; Asparouhov, Tihomir; Morin, Alexandre J. S.; Trautwein, Ulrich; Nagengast, Benjamin
2010-01-01
NEO instruments are widely used to assess Big Five personality factors, but confirmatory factor analyses (CFAs) conducted at the item level do not support their a priori structure due, in part, to the overly restrictive CFA assumptions. We demonstrate that exploratory structural equation modeling (ESEM), an integration of CFA and exploratory…
ERIC Educational Resources Information Center
Okech, David
2012-01-01
Objectives: Using baseline and second wave data, the study evaluated the measurement and structural properties of parenting stress, personal mastery, and economic strain with N = 381 lower income parents who decided to join and those who did not join in a child development savings account program. Methods: Structural equation modeling mean and…
A semiparametric Bayesian approach for structural equation models.
Song, Xin-Yuan; Pan, Jun-Hao; Kwok, Timothy; Vandenput, Liesbeth; Ohlsson, Claes; Leung, Ping-Chung
2010-06-01
In the development of structural equation models (SEMs), observed variables are usually assumed to be normally distributed. However, this assumption is likely to be violated in many practical researches. As the non-normality of observed variables in an SEM can be obtained from either non-normal latent variables or non-normal residuals or both, semiparametric modeling with unknown distribution of latent variables or unknown distribution of residuals is needed. In this article, we find that an SEM becomes nonidentifiable when both the latent variable distribution and the residual distribution are unknown. Hence, it is impossible to estimate reliably both the latent variable distribution and the residual distribution without parametric assumptions on one or the other. We also find that the residuals in the measurement equation are more sensitive to the normality assumption than the latent variables, and the negative impact on the estimation of parameters and distributions due to the non-normality of residuals is more serious. Therefore, when there is no prior knowledge about parametric distributions for either the latent variables or the residuals, we recommend making parametric assumption on latent variables, and modeling residuals nonparametrically. We propose a semiparametric Bayesian approach using the truncated Dirichlet process with a stick breaking prior to tackle the non-normality of residuals in the measurement equation. Simulation studies and a real data analysis demonstrate our findings, and reveal the empirical performance of the proposed methodology. A free WinBUGS code to perform the analysis is available in Supporting Information. PMID:20533410
Structural relaxation in atomic clusters: Master equation dynamics
NASA Astrophysics Data System (ADS)
Miller, Mark A.; Doye, Jonathan P. K.; Wales, David J.
1999-10-01
The role of the potential energy landscape in determining the relaxation dynamics of model clusters is studied using a master equation. Two types of energy landscape are examined: a single funnel, as exemplified by 13-atom Morse clusters, and the double funnel landscape of the 38-atom Lennard-Jones cluster. Interwell rate constants are calculated using Rice-Ramsperger-Kassel-Marcus theory within the harmonic approximation, but anharmonic model partition functions are also considered. Decreasing the range of the potential in the Morse clusters is shown to hinder relaxation toward the global minimum, and this effect is related to the concomitant changes in the energy landscape. The relaxation modes that emerge from the master equation are interpreted and analyzed to extract interfunnel rate constants for the Lennard-Jones cluster. Since this system is too large for a complete characterization of the energy landscape, the conditions under which the master equation can be applied to a limited database are explored. Connections are made to relaxation processes in proteins and structural glasses.
Structural Equation Modeling: Applications in ecological and evolutionary biology research
Pugesek, Bruce H.; von Eye, Alexander; Tomer, Adrian
2003-01-01
This book presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems. Supplementary information can be found at the authors website, http://www.jamesbgrace.com/. ? Details why multivariate analyses should be used to study ecological systems ? Exposes unappreciated weakness in many current popular analyses ? Emphasizes the future methodological developments needed to advance our understanding of ecological systems.
Structure detection of semiparametric structural equation models with Bayesian adaptive group lasso.
Feng, Xiang-Nan; Wang, Guo-Chang; Wang, Yi-Fan; Song, Xin-Yuan
2015-04-30
Structural equation models (SEMs) are widely recognized as the most important statistical tool for assessing the interrelationships among latent variables. This study develops a Bayesian adaptive group least absolute shrinkage and selection operator procedure to perform simultaneous model selection and estimation for semiparametric SEMs, wherein the structural equation is formulated using the additive nonparametric functions of observed and latent variables. We propose the use of basis expansions to approximate the unknown functions. By introducing adaptive penalties to the groups of basis expansions, the nonlinear, linear, or non-existent effects of observed and latent variables in the structural equation can be automatically detected. A simulation study demonstrates that the proposed method performs satisfactorily. This paper presents an application of revealing the observed and latent risk factors of diabetic kidney disease. PMID:25640461
2014-01-01
Background Early feeding practices lay the foundation for children’s eating habits and weight gain. Questionnaires are available to assess parental feeding but overlapping and inconsistent items, subscales and terminology limit conceptual clarity and between study comparisons. Our aim was to consolidate a range of existing items into a parsimonious and conceptually robust questionnaire for assessing feeding practices with very young children (<3 years). Methods Data were from 462 mothers and children (age 21–27 months) from the NOURISH trial. Items from five questionnaires and two study-specific items were submitted to a priori item selection, allocation and verification, before theoretically-derived factors were tested using Confirmatory Factor Analysis. Construct validity of the new factors was examined by correlating these with child eating behaviours and weight. Results Following expert review 10 factors were specified. Of these, 9 factors (40 items) showed acceptable model fit and internal reliability (Cronbach’s ?: 0.61-0.89). Four factors reflected non-responsive feeding practices: ‘Distrust in Appetite’, ‘Reward for Behaviour’, ‘Reward for Eating’, and ‘Persuasive Feeding’. Five factors reflected structure of the meal environment and limits: ‘Structured Meal Setting’, ‘Structured Meal Timing’, ‘Family Meal Setting’, ‘Overt Restriction’ and ‘Covert Restriction’. Feeding practices generally showed the expected pattern of associations with child eating behaviours but none with weight. Conclusion The Feeding Practices and Structure Questionnaire (FPSQ) provides a new reliable and valid measure of parental feeding practices, specifically maternal responsiveness to children’s hunger/satiety signals facilitated by routine and structure in feeding. Further validation in more diverse samples is required. PMID:24898364
A Y-like structure in Jupiter's equator
NASA Astrophysics Data System (ADS)
Barrado-Izagirre, N.; Legarreta, J.; García-Melendo, E.; Sánchez-Lavega, A.; Gómez-Forrellad, J. M.
2015-10-01
In this work we are presenting a study of peculiar Y-shaped structures that appeared in the equatorial zone of Jupiter between September and December 2012.These low albedo structures (named Y1 and Y2) were oriented along the equator and centered on it (at latitude 0.5ºto 1ºN). By using images acquired by a worldwide network of observers contributing to the PVOL-IOPW database [3] and operating small telescopes,we have analyzed the morphology of the structures and the surrounding area as well as the dynamical evolution during their lifetime 90 and 60 days respectively. In this period of time convective activity was registered near the vertex of these structures. We have complemented the study with a set of images in ultraviolet and near infrared wavelengths obtained by the Hubble Space Telescope (HST) for this epoch. The features were not visible at 255 nm wavelengths which indicate that they were vertically thin and placed in altitude between the upper Equatorial hazes and the main cloud deck. In addition, they move faster than their surroundings. Finally, we interpret the phenomenon as the manifestation of a transient equatorially trapped Kelvin wave.
ERIC Educational Resources Information Center
Aguado, Jaume; Campbell, Alistair; Ascaso, Carlos; Navarro, Purificacion; Garcia-Esteve, Lluisa; Luciano, Juan V.
2012-01-01
In this study, the authors tested alternative factor models of the 12-item General Health Questionnaire (GHQ-12) in a sample of Spanish postpartum women, using confirmatory factor analysis. The authors report the results of modeling three different methods for scoring the GHQ-12 using estimation methods recommended for categorical and binary data.…
ERIC Educational Resources Information Center
Forde, David R.; Baron, Stephen W.; Scher, Christine D.; Stein, Murray B.
2012-01-01
This study examines the psychometric properties of the Childhood Trauma Questionnaire short form (CTQ-SF) with street youth who have run away or been expelled from their homes (N = 397). Internal reliability coefficients for the five clinical scales ranged from 0.65 to 0.95. Confirmatory Factor Analysis (CFA) was used to test the five-factor…
ERIC Educational Resources Information Center
Ottmar, Erin R.; Konold, Timothy R.; Berry, Robert Q.; Grissmer, David W.; Cameron, Claire E.
2014-01-01
Psychometric properties of 24 items from the fifth grade Early Childhood Longitudinal Study-Kindergarten Cohort Mathematics Teacher Questionnaire were investigated in a sample of 5,181 participants. These items asked teachers to report how often they had their classroom students engage in different mathematics content, skills and instructional…
ERIC Educational Resources Information Center
Caballo, C.; Crespo, M.; Jenaro, C.; Verdugo, M. A.; Martinez, J. L.
2005-01-01
Background: The Quality of Life Questionnaire (QOL-Q) is used widely to evaluate the quality of life of persons with intellectual disability (ID). Its validity for use with Spanish-speaking cultures has been demonstrated for individuals with visual disabilities, but not for those with physical or intellectual disabilities. Such was the purpose of…
ERIC Educational Resources Information Center
Ausderau, Karla; Sideris, John; Furlong, Melissa; Little, Lauren M.; Bulluck, John; Baranek, Grace T.
2014-01-01
This national online survey study characterized sensory features in 1,307 children with autism spectrum disorder (ASD) ages 2-12 years using the Sensory Experiences Questionnaire Version 3.0 (SEQ-3.0). Using the SEQ-3.0, a confirmatory factor analytic model with four substantive factors of hypothesized sensory response patterns (i.e.,…
NASA Astrophysics Data System (ADS)
Slemrod, M.
1990-12-01
This paper considers an infinite system of partial differential equations, the coagulation-diffusion equations, which add spatial diffusion to the classical coagulation equations. The main emphasis is placed on deriving an infinite system of ordinary differential equations which described the structured interface between reacting coagulation and dilute concentration. Existence of solutions to interfacial equaitons is proven under spatial boundary conditions.
Bayesian Learning of Genetic Network Structure in the Space of Differential Equation Models
Kaban, Ata
Bayesian Learning of Genetic Network Structure in the Space of Differential Equation Models Daniel.Kaban@cs.bham.ac.uk) Keywords: gene networks, differential equations, Metropolis-Hastings, Bayesian model inference and model, non-linear differential equations. Differential equation models were used before as a means
Global Structure and Asymptotic Behavior of Weak Solutions to Flood Wave Equations
Global Structure and Asymptotic Behavior of Weak Solutions to Flood Wave Equations Tao Luo: Flood wave equations, Weak solutions, Relaxation, Shock waves Abstract The present paper concerns with the global structure and asymptotic behavior of the discontinuous solutions to flood wave equations
Structural equation models of VMT growth in US urbanised areas.
Ewing, Reid; Hamidi, Shima; Gallivan, Frank; Nelson, Arthur C.; Grace, James B.
2014-01-01
Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its kind. The cross-sectional and longitudinal models together, plus the transportation literature generally, give us a basis for generalising across studies to arrive at elasticity values of VMT with respect to different urban variables.
NASA Astrophysics Data System (ADS)
Papanikolaou, Dimitrios; Papanikolaou, Ioannis; Diakakis, Michalis; Deligiannakis, Georgios
2013-04-01
In the face of a growing number of natural disasters and the increasing costs associated with them, Europe and Greece in particular, have devoted significant efforts and resources in natural hazards mitigation during the last decades. Despite the significant legislative efforts (e.g. 1998/22/EC, 2001/792/EC, 2007/60/EC Directives, 3013/2002 Act) and even though a number of steps has been taken towards improving civil protection, recent catastrophic events have illustrated the weaknesses of current approaches. In particular, in Greece, events such as the 1999 Athens earthquake, the 2007 and 2009 wildfires have shown the inadequacy of prevention and mitigation practices. Given the enhanced civil protection responsibilities, given by the Greek national law (Acts 3013/2002, 3852/2010) to local authorities in Greece, this work analyses and evaluates the existing structure and current management framework under which local authorities function and examines their risk mitigation practices. We conducted the largest questionnaire survey regarding Civil Protections issues, among the municipalities of Greece. To this aim, this work used a innovative online tool to assess current framework. Therefore, a network connecting civil protection departments of municipalities was developed, based on an Internet platform that acted also as a communication tool. Overall, we had feedback either online or offline from 125 municipalities across the country (representing more than one/third of the total municipalities of Greece). Through this network, municipal civil protection officials completed surveys designed to obtain and quantify information on several aspects of civil protection practices and infrastructure. In particular, the examined factors included: (i) personnel and equipment, (ii) inter-agency cooperation, (iii) training, (iv) compliance with existing regulations and (v) persistent problems encountered by civil protection departments, that prevent the effectiveness of current practices. Responses showed that civil protection personnel lack adequate training and expertise, many are overstretched with several duties, while several prevention actions are carried out by seasonal or voluntary staff. Approximately half of the heads of civil protection offices do not hold a university degree, only 27% have a relevant scientific background (geoscientists or engineers) and more than half of them are elected members and not permanent staff, implying that no continuity is secured. Inter-agency cooperation is shown to be poor and organizational learning from international practices not adequate. Half of the municipalities report that the authorization processes are too slow so that prevention actions particularly regarding forest fires are severely delayed. Existing regulations are not followed by a significant portion of municipalities since 19% have not established a civil protection office and 23% have not compiled an action plan yet. Existing action plans lack important information, present no spatial data and are predominantly catalogues and tables of information regarding authorised personnel and equipment. Overall, underfunding, poor coordination of the different actors involved, lack of training and understaffing, lack of proper equipment and several other issues are held responsible by officials for preventing effectiveness of current practices. Finally, the EU emergency number 112 is widely unknown (87%). This work was held under the LIFE+ project "Local Authorities Alliance for Forest Fire Prevention - LIFE08/ENV/GR/000553" which is implemented with the contribution of the LIFE financial instrument of the European Community.
Two-vortex structure of electron, nonlocality and Dirac equation
S. C. Tiwari
2012-01-20
The dimensionless electromagnetic coupling constant $\\alpha=e^2 /\\hbar c$ may have three interpretations: as the well known ratio between the electron charge radius $e^2/mc^2$ and the Compton wavelength of electron $\\lambda_c= \\hbar /mc$, as a ratio of two angular momenta since Planck constant has the dimension of angular momentum, and two flux quanta $e$ and $hc/e$. The anomalous part of the electron magnetic moment together with the unified picture of the three interpretations of $\\alpha$ is suggested to have deep physical significance. The electric charge is proposed to be a new quantum of flux such that a two-vortex structure of electron is envisaged. In analogy with quantum conditions we postulate sub-quantum conditions applicable in a region of the order of $\\lambda_c$ replacing $\\hbar$ by a universal constant $f=e^2 /2\\pi c$ and apply it to Dirac equation in internal space that gives rise to the anomalous magnetic moment of electron. Dirac spinor and 2-spinor representation for vortex structure of electron in the single particle Dirac framework are discussed. The role of sub-quantum rules and the internal variables for developing the present ideas is also debated. A critical discussion on the past attempts to give fundamental importance to magnetism and flux quantum is given to delineate the new ideas in the present work.
Equation of State of Structured Matter at Finite Temperature
NASA Astrophysics Data System (ADS)
Maruyama, T.; Yasutake, N.; Tatsumi, T.
We investigate the properties of nuclear matter at the first-order phase transitions such as liquid-gas phase transition and hadron-quark phase transition. As a general feature of the first-order phase transitions of matter consisting of many species of charged particles, there appears a mixed phases with geometrical structures called ``pasta'' due to the balance of the Coulomb repulsion and the surface tension between two phases [G.~D.~Ravenhall, C.~J.~Pethick and J.~R.~Wilson, Phys. Rev. Lett. 50 (1983), 2066. M.~Hashimoto, H.~Seki and M.~Yamada, Prog. Theor. Phys. 71 (1984), 320.] The equation of state (EOS) of mixed phase is different from the one obtained by a bulk application of the Gibbs conditions or by the Maxwell construction due to the effects of the non-uniform structure. We show that the charge screening and strong surface tension make the EOS close to that of the Maxwell construction. The thermal effects are elucidated as well as the above finite-size effects.
Questionnaire Development Resources
Downloadable resources made available by DCEG for use in developing study questionnaires. Includes questionnaires reviewed and approved by DCEG’s Technical Evaluation Committee, as well as non-reviewed questionnaire modules to be used as starting points for development.
Vilhena, Estela; Pais-Ribeiro, José; Silva, Isabel; Cardoso, Helena; Mendonça, Denisa
2014-01-01
Living with obesity is an experience that may affect multiple aspects of an individual's life. Obesity is considered a relevant public health problem in modern societies. To determine the comparative efficacy of different treatments and to assess their impact on patients' everyday life, it is important to identify factors that are relevant to the quality of life of obese patients. The present study aims to evaluate, in Portuguese obese patients, the simultaneous impact of several psychosocial factors on quality of life. This study also explores the mediating role of stigma in the relationship between positive/negative affect and quality of life. A sample of 215 obese patients selected from the main hospitals in Portugal completed self-report questionnaires to assess sociodemographic, clinical, psychosocial, and quality of life variables. Data were analysed using structural equation modeling. The model fitted the data reasonably well, CFI = 0.9, RMSEA = 0.06. More enthusiastic and more active patients had a better quality of life. Those who reflect lower perception of stigma had a better physical and mental health. Partial mediation effects of stigma between positive affect and mental health and between negative affect and physical health were found. The stigma is pervasive and causes consequences for psychological and physical health. PMID:24693421
Online Social Presence: Score Validity of the Computer-Mediated Communication Questionnaire
ERIC Educational Resources Information Center
Yen, Cherng-Jyh
2008-01-01
The purpose of this study was to conduct a confirmatory factor analysis of the Computer-Mediated Communication Questionnaire scores, using structural equation modeling, to assess the consistency between the empirical data and the hypothesized factor structure of the CMCQ in the proposed models, which is stipulated by the theoretical framework and…
Critical Missing Equation of Quantum Physics for Understanding Atomic Structures
Xiaofei Huang
2013-11-01
This paper presents an optimization approach to explain why and how a quantum system evolves from an arbitrary initial state to a stationary state, satisfying the time-independent Schr\\"{o}dinger equation. It also points out the inaccuracy of this equation, which is critial important in quantum mechanics and quantum chemistry, due to a fundamental flaw in it conflicting with the physical reality. The some directions are suggested on how to modify the equation to fix the problem
Energy conservation equations and interaction contributions at a structural interface between two
Cerveny, Vlastislav
Energy conservation equations and interaction contributions at a structural interface between twoÂmails: johana@seis.karlov.mff.cuni.cz, vcerveny@seis.karlov.mff.cuni.cz Summary Energy conservation equations is to investigate numeriÂ cally the energy conservation equations and the interaction contributions. An attempt
ERIC Educational Resources Information Center
Ritter, Lois A. Ed.; Sue, Valerie M., Ed.
2007-01-01
Internet-based surveys are still relatively new, and researchers are just beginning to articulate best practices for questionnaire design. Online questionnaire design has generally been guided by the principles applying to other self-administered instruments, such as paper-based questionnaires. Web-based questionnaires, however, have the potential…
Hard ellipses: Equation of state, structure and self-diffusion
Wen-Sheng Xu; Yan-Wei Li; Zhao-Yan Sun; Li-Jia An
2013-06-26
We present an event-driven molecular dynamics study for hard ellipses and assess the effects of aspect ratio and area fraction on their physical properties. For state points in the plane of aspect ratio (k=1-9) and area fraction (phi=0.01-0.8), we identify three different phases, including isotropic, plastic and nematic states. The equation of state (EOS) is shown for a wide range of aspect ratios and is compared with the scaled particle theory (SPT) for the isotropic states. We find that SPT provides a good description of the EOS for the isotropic phase of hard ellipses. At large fixed phi, the reduced pressure p increases with k in both the isotropic and the plastic phases, and interestingly, its dependence on k is rather weak in the nematic phase. We rationalize the thermodynamics of hard ellipses in terms of particle motions. The plastic crystal is shown to form for aspect ratios up to k=1.4, while appearance of the stable nematic phase starts approximately at k=3. We quantitatively determine the locations of the isotropic-plastic (I-P) transition and the isotropic-nematic (I-N) transition by analyzing the bond-orientation correlations and the angular correlations, respectively. As expected, the I-P transition point is found to increase with k, while a larger k leads to a smaller area fraction where the I-N transition takes place. Moreover, our simulations strongly support that the two-dimensional nematic phase in hard ellipses has only quasi-long-range orientational order. The self-diffusion of hard ellipses is further explored and connections are revealed between the structure and the self-diffusion. We discuss the relevance of our results to the glass transition in hard ellipses. Finally, the results of the isodiffusivity lines are evaluated for hard ellipses and we discuss the effect of spatial dimension on the diffusive dynamics of hard ellipsoidal particles.
Inferring causal phenotype networks using structural equation models.
Rosa, Guilherme J M; Valente, Bruno D; de los Campos, Gustavo; Wu, Xiao-Lin; Gianola, Daniel; Silva, Martinho A
2011-01-01
Phenotypic traits may exert causal effects between them. For example, on the one hand, high yield in dairy cows may increase the liability to certain diseases and, on the other hand, the incidence of a disease may affect yield negatively. Likewise, the transcriptome may be a function of the reproductive status in mammals and the latter may depend on other physiological variables. Knowledge of phenotype networks describing such interrelationships can be used to predict the behavior of complex systems, e.g. biological pathways underlying complex traits such as diseases, growth and reproduction. Structural Equation Models (SEM) can be used to study recursive and simultaneous relationships among phenotypes in multivariate systems such as genetical genomics, system biology, and multiple trait models in quantitative genetics. Hence, SEM can produce an interpretation of relationships among traits which differs from that obtained with traditional multiple trait models, in which all relationships are represented by symmetric linear associations among random variables, such as covariances and correlations. In this review, we discuss the application of SEM and related techniques for the study of multiple phenotypes. Two basic scenarios are considered, one pertaining to genetical genomics studies, in which QTL or molecular marker information is used to facilitate causal inference, and another related to quantitative genetic analysis in livestock, in which only phenotypic and pedigree information is available. Advantages and limitations of SEM compared to traditional approaches commonly used for the analysis of multiple traits, as well as some indication of future research in this area are presented in a concluding section. PMID:21310061
Meta-Analytic Structural Equation Modeling (MASEM): Comparison of the Multivariate Methods
ERIC Educational Resources Information Center
Zhang, Ying
2011-01-01
Meta-analytic Structural Equation Modeling (MASEM) has drawn interest from many researchers recently. In doing MASEM, researchers usually first synthesize correlation matrices across studies using meta-analysis techniques and then analyze the pooled correlation matrix using structural equation modeling techniques. Several multivariate methods of…
ERIC Educational Resources Information Center
Maslowsky, Julie; Jager, Justin; Hemken, Douglas
2015-01-01
Latent variables are common in psychological research. Research questions involving the interaction of two variables are likewise quite common. Methods for estimating and interpreting interactions between latent variables within a structural equation modeling framework have recently become available. The latent moderated structural equations (LMS)…
On bi-Hamiltonian structure of two-component Novikov equation
NASA Astrophysics Data System (ADS)
Li, Nianhua; Liu, Q. P.
2013-01-01
In this Letter, we present a bi-Hamiltonian structure for the two-component Novikov equation. We also show that proper reduction of this bi-Hamiltonian structure leads to the Hamiltonian operators found by Hone and Wang for the Novikov equation.
Progress in Integrated Fluid/Structure/Controls Computations Using High Fidelity Equations
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; VanDalsem, William R. (Technical Monitor)
1995-01-01
Aeroelasticity that involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of aircraft which can experience complex flow/structure interactions. Supersonic transports can experience vortex induced aeroelastic oscillations whereas subsonic transports can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Using these high fidelity methods, design quantities such as structural stresses can be directly computed. Computations using these high fidelity equations require state-of-the-art large computational resources. This paper will describe the transition from potential equations to Euler/Navier-Stokes equations for fluids and from modal equations to finite element equations for structures. Complexities associated with grids for moving control surfaces will be discussed. All contents of the paper will be limited to those already presented at domestic conferences within U.S. such as those sponsored by AIAA. It will not include any materials related to HPCCP computational work.
Appendix B: Questionnaire B1: Questionnaire
. Where was the study child born? City ST ___ ___ Country 6. What is the child's sex? Male Female 7. HowAppendix B: Questionnaire B1: Questionnaire #12;Do not write in this space To protect your child/her as the "study child". This page, which includes his/her personal information, will be separated from the rest
On the band gap structure of Hill's equation
NASA Astrophysics Data System (ADS)
Allaire, G.; Orive, R.
2005-06-01
We revisit the old problem of finding the stability and instability intervals of a second-order elliptic equation on the real line with periodic coefficients (Hill's equation). It is well known that the stability intervals correspond to the spectrum of the Bloch family of operators defined on a single period. Here we propose a characterization of the instability intervals. We introduce a new family of non-self-adjoint operators, formally equivalent to the Bloch ones but with an imaginary Bloch parameter, that we call exponential. We prove that they admit a countable infinite number of eigenvalues which, when they are real, completely characterize the intervals of instability of Hill's equation.
Pajulo, Marjukka; Tolvanen, Mimmi; Karlsson, Linnea; Halme-Chowdhury, Elina; Öst, Camilla; Luyten, Patrick; Mayes, Linda; Karlsson, Hasse
2015-01-01
Parental reflective functioning (PRF) is the capacity to focus on experience and feelings in oneself and in the child. Individual differences in PRF reportedly affect child attachment and socioemotional development. In this study, we report work on developing a questionnaire to assess PRF during pregnancy (Prenatal Parental Reflective Functioning Questionnaire; P-PRFQ). The factor structure of the 33-item version of the P-PRFQ was explored using pilot study data from the Finn Brain Birth Cohort Study (n = 124 mothers, n = 82 fathers). Construct validity was assessed against the Pregnancy Interview (PI; A. Slade, L. Grunebaum, L. Huganir, & M. Reeves, 1987, 2002, 2011) in a subsample of 29 mothers from the same pilot sample. Exploratory and confirmatory factor analysis resulted in a 14-item P-PRFQ, with three factors which seem to capture relevant aspects of prenatal parental mentalization-F1: "Opacity of mental states," F2: "Reflecting on the fetus-child," and F3: "The dynamic nature of the mental states." Functioning of the factor structure was further tested in the large cohort with 600 mothers and 600 fathers. Correlations with the PI result were high, both regarding total and factor scores of the P-PRFQ. Cost-effective tools to assess key areas of early parenting are needed for both research and clinical purposes. The 14-item P-PRFQ seems to be an applicable and promising new tool for assessing very early parental mentalizing capacity. PMID:26096692
NASA Technical Reports Server (NTRS)
Hou, Gene; Koganti, Gopichand
1993-01-01
Controls-structure integrated design is a complicated multidisciplinary design optimization problem which involves the state equations pertaining to open-loop eigenvalues and control laws. In order to alleviate the intensity of the computation, this study uses the adjoint variable method to derive sensitivity equations for the eigenvalue, Liapunov, and Riccati equations. These individual sensitivity equations are then combined together to form the multidisciplinary sensitivity equations for the control structure integrated design problems. A set of linear sensitivity equations, proportional in number to the number of performance functions involved in the optimization process, are solved. This proposed approach may provide a great saving in computer resources. The validity of the newly developed sensitivity equations is verified by numerical examples.
System Characteristics, Satisfaction and E-Learning Usage: A Structural Equation Model (SEM)
ERIC Educational Resources Information Center
Ramayah, T.; Lee, Jason Wai Chow
2012-01-01
With the advent of the Internet, more and more public universities in Malaysia are putting in effort to introduce e-learning in their respective universities. Using a structured questionnaire derived from the literature, data was collected from 250 undergraduate students from a public university in Penang, Malaysia. Data was analyzed using AMOS…
Hamiltonian structure of propagation equations for ultrashort optical pulses
NASA Astrophysics Data System (ADS)
Amiranashvili, Sh.; Demircan, A.
2010-07-01
A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring to the quantum creation and annihilation operators. The derived z-propagated Hamiltonian accounts for forward and backward waves, arbitrary medium dispersion, and four-wave mixing processes. As a simple application we obtain integrals of motion for the pulse propagation. The integrals reflect time-averaged fluxes of energy, momentum, and photons transferred by the pulse. Furthermore, pulses in the form of stationary nonlinear waves are considered. They yield extremal values of the momentum flux for a given energy flux. Simplified propagation equations are obtained by reduction of the Hamiltonian. In particular, the complex electric field reduces to an analytic signal for the unidirectional propagation. Solutions of the full bidirectional model are numerically compared to the predictions of the simplified equation for the analytic signal and to the so-called forward Maxwell equation. The numerics is effectively tested by examining the conservation laws.
Hamiltonian structure of propagation equations for ultrashort optical pulses
Amiranashvili, Sh.; Demircan, A.
2010-07-15
A Hamiltonian framework is developed for a sequence of ultrashort optical pulses propagating in a nonlinear dispersive medium. To this end a second-order nonlinear wave equation for the electric field is transformed into a first-order propagation equation for a suitably defined complex electric field. The Hamiltonian formulation is then introduced in terms of normal variables, i.e., classical complex fields referring to the quantum creation and annihilation operators. The derived z-propagated Hamiltonian accounts for forward and backward waves, arbitrary medium dispersion, and four-wave mixing processes. As a simple application we obtain integrals of motion for the pulse propagation. The integrals reflect time-averaged fluxes of energy, momentum, and photons transferred by the pulse. Furthermore, pulses in the form of stationary nonlinear waves are considered. They yield extremal values of the momentum flux for a given energy flux. Simplified propagation equations are obtained by reduction of the Hamiltonian. In particular, the complex electric field reduces to an analytic signal for the unidirectional propagation. Solutions of the full bidirectional model are numerically compared to the predictions of the simplified equation for the analytic signal and to the so-called forward Maxwell equation. The numerics is effectively tested by examining the conservation laws.
Park, Byung-Chan; Kim, Eun-A; Kim, Soo Geun
2010-01-01
Objectives This study was conducted to develop a model describing the interaction between lifestyle, job, and postural factors and parts of the upper extremities in shipyard workers. Methods A questionnaire survey was given to 2,140 workers at a shipyard in Ulsan City. The questionnaire consisted of questions regarding the subjects' general characteristics, lifestyle, tenure, physical burden, job control, posture and musculoskeletal symptoms. The overall relationship between variables was analyzed by a structural equation model (SEM). Results The positive rate of upper extremity musculoskeletal symptoms increased in employees who worked longer hours, had severe physical burden, and did not have any control over their job. Work with a more frequent unstable posture and for longer hours was also associated with an increased positive rate of musculoskeletal symptoms. Multiple logistic regression analysis showed that unstable posture and physical burden were closely related to the positive rate of musculoskeletal symptoms after controlling for age, smoking, drinking, exercise, tenure, and job control. In SEM analysis, work-related musculoskeletal disease was influenced directly and indirectly by physical and job stress factors, lifestyle, age, and tenure (p < 0.05). The strongest correlations were found between physical factors and work-related musculoskeletal disease. Conclusion The model in this study provides a better approximation of the complexity of the actual relationship between risk factors and work-related musculoskeletal disorders. Among the variables evaluated in this study, physical factors (work posture) had the strongest association with musculoskeletal disorders. PMID:22953172
Rassin, E; Muris, P; Schmidt, H; Merckelbach, H
2000-09-01
Research has shown that there are strong similarities in content between the obsessions and compulsions that characterize obsessive-compulsive disorder and nonclinical obsessions and compulsions. However, clinical and nonclinical obsessions and compulsions do differ with respect to characteristics like frequency, intensity, discomfort and elicited resistance. Two separate concepts have been invoked to explain how normal obsessions and compulsions may develop into clinical phenomena. First, it is suggested that thought-action fusion (TAF) contributes to obsessive-compulsive symptoms. Second, thought suppression may intensify obsessive-compulsive symptoms due to its paradoxical effect on intrusive thoughts. Although both phenomena have been found to contribute to obsessive-compulsive symptoms, possible interactions between these two have never been investigated. The current study explored how TAF and thought suppression interact in the development of obsessive-compulsive symptoms. Undergraduate psychology students (N = 173) completed questionnaires pertaining to TAF, thought suppression and obsessive-compulsive symptoms. Covariances between the scores on these questionnaires were analyzed by means of structural equation modeling. Results suggest that TAF triggers thought suppression, while thought suppression, in turn, promotes obsessive-compulsive symptoms. PMID:10957823
ERIC Educational Resources Information Center
Smith, Dennis W.; Lee, Jay T.; Colwell, Brian; Stevens-Manser, Stacey
2008-01-01
In response to the problem of adolescent smoking and limited appropriate cessation resources, this study examined the pattern and structure of the American Lung Association, Why Do You Smoke? (WDS) to determine its appropriateness for use in youth smoking cessation programs. The WDS is used to help smokers identify primary motivations for using…
2012-01-01
Background The Recalled Parental Rearing Behavior questionnaire (FEE, [1,2]) assesses perceived parental rearing behavior separately for each parent. An ultra-short screening version (FEE-US) with the same three scales each for the mother and the father is reported and factor-analytically validated. Methods N = 4,640 subjects aged 14 to 92 (M = 48.4 years) were selected by the random-route sampling method. The ultra-short questionnaire version was derived from the long version through item and factor analyses. In a confirmatory factor analysis framework, the hypothesized three-factorial structure was fitted to the empirical data and tested for measurement invariance, differential item functioning, item discriminability, and convergent and discriminant factorial validity. Effects of gender or age were assessed using MANOVAs. Results The a-priori hypothesized model resulted in mostly adequate overall fit. Neither gender nor age group yielded considerable effects on the factor structure, but had small effects on means of raw score sums. Factorial validities could be confirmed. Scale sums are well-suited to rank respondents along the respective latent dimension. Conclusion The structure of the long version with the factors Rejection & Punishment, Emotional Warmth, and Control & Overprotection could be replicated for both father and mother items in the ultra-short screening version using confirmatory factor analyses. These results indicate that the ultra-short screening version is a time-saving and promising screening instrument for research settings and in individual counseling. However, the shortened scales do not necessarily represent the full spectrum covered by the full-scale dimensions. PMID:23134704
Yi Zhu; Jianke Yang
2007-03-14
Weak interactions of solitary waves in the generalized nonlinear Schr\\"{o}dinger equations are studied. It is first shown that these interactions exhibit similar fractal dependence on initial conditions for different nonlinearities. Then by using the Karpman-Solov'ev method, a universal system of dynamical equations is derived for the velocities, amplitudes, positions and phases of interacting solitary waves. These dynamical equations contain a single parameter, which accounts for the different forms of nonlinearity. When this parameter is zero, these dynamical equations are integrable, and the exact analytical solutions are derived. When this parameter is non-zero, the dynamical equations exhibit fractal structures which match those in the original wave equations both qualitatively and quantitatively. Thus the universal nature of fractal structures in the weak interaction of solitary waves is analytically established. The origin of these fractal structures is also explored. It is shown that these structures bifurcate from the initial conditions where the solutions of the integrable dynamical equations develop finite-time singularities. Based on this observation, an analytical criterion for the existence and locations of fractal structures is obtained. Lastly, these analytical results are applied to the generalized nonlinear Schr\\"{o}dinger equations with various nonlinearities such as the saturable nonlinearity, and predictions on their weak interactions of solitary waves are made.
Pendergast, Laura L.; Scharf, Rebecca J.; Rasmussen, Zeba A.; Seidman, Jessica C.; Schaefer, Barbara A.; Svensen, Erling; Tofail, Fahmida; Koshy, Beena; Kosek, Margaret; Rasheed, Muneera A.; Roshan, Reeba; Maphula, Angelina; Shrestha, Rita; Murray-Kolb, Laura E.
2014-01-01
Background The Self-Reporting Questionnaire (SRQ) is a screening instrument that has been shown to be an effective measure of depression in postpartum women and is widely used in developing nations. Methods The SRQ was administered to 2,028 mothers from eight nations at two time points: one and six months postpartum. All data were obtained from the Interactions of Malnutrition and Enteric Infections: Consequences for Child Health and Development (MAL-ED) study. The sample included women from MAL-ED sites in Bangladesh, Brazil, India, Nepal, Pakistan, Peru, South Africa, and Tanzania. This study examined three aspects of validity of SRQ scores including (a) structural validity, (b) cross-cultural invariance, and (c) invariance over time. Results A 16-item, one-factor structure with items reflecting somatic symptoms removed was deemed to be superior to the original structure in this postpartum population. Although differential item functioning (DIF) across sites was evident, the one-factor model was a good fit to the data from seven sites, and the structure was invariant across the one- and six-month time points. Limitations Findings are based on data from self-report scales. No information about the clinical status of the participants was available. Conclusions Overall, findings support the validity of a modified model of the SRQ among postpartum women. Somatic symptoms (e.g., headaches, not sleeping well) may not reflect internalizing problems in a postpartum population. Implications for researchers and practitioners are discussed. PMID:24981251
Structure of Helicity and Global Solutions of Incompressible Navier-Stokes Equation
NASA Astrophysics Data System (ADS)
Lei, Zhen; Lin, Fang-Hua; Zhou, Yi
2015-12-01
In this paper we derive a new energy identity for the three-dimensional incompressible Navier-Stokes equations by a special structure of helicity. The new energy functional is critical with respect to the natural scalings of the Navier-Stokes equations. Moreover, it is conditionally coercive. As an application we construct a family of finite energy smooth solutions to the Navier-Stokes equations whose critical norms can be arbitrarily large.
Assessing Epistemological Beliefs: Schommer's Questionnaire Revisited.
ERIC Educational Resources Information Center
Clarebout, Geraldine; Elen, Jan; Luyten, Lieve; Bamps, Hadewych
2001-01-01
Reviewed the literature on the questionnaire developed by M. Schommer to assess epistemological beliefs and studied the factor structure of the questionnaire in 2 studies involving 117 junior college students and 148 university students. In neither study could Schommer's factor structure be retrieved. Results reveal counter-indications to the use…
Ostermann, Thomas; Büssing, Arndt; Beer, Andre-Michael; Matthiessen, Peter F
2005-01-01
Background Quality of life (QoL) of patients has become a central evaluation parameter that also acts as an aid for decisions related to treatment strategies particularly for patients with chronic illnesses. In Germany, one of the newer instruments attempting to measure distinct QoL aspects is the "Herdecke Questionnaire for Quality of Life" (HLQ). In this study, we aimed to validate the HLQ with respect to its factorial structure, and to develop a short form. The validation has been carried out in relation to other questionnaires including the SF-36 Health Survey, the Mood-Scale Bf-S, the Giessen Physical Complaints Questionnaire GBB-24 and McGill's Pain Perception Scale SES. Methods Data for this study derived from a model project on the treatment of patients using naturopathy methods in Blankenstein Hospital, Hattingen. In total, 2,461 patients between the ages of 16 and 92 years (mean age: 58.0 ± 13.4 years) were included in this study. Most of the patients (62%) suffered from rheumatic diseases. Factorial validation of the HLQ, it's reliability and external consistency analysis and the development of a short form were carried out using the SPSS software. Results Structural analysis of the HLQ-items pointed to a 6-factor model. The internal consistency of both the long and the short version is excellent (Cronbach's ? is 0.935 for the HLQ-L and 0.862 for the HLQ-S). The highest reliability in the HLQ-L was obtained for the "Initiative Power and Interest" scale, the lowest for the 2-item scales "Digestive Well-Being" and the "Physical Complaints". However, the scales found by factor analysis herein were only in part congruent with the original 5-scale model which was approved a multitrait analysis approach. The new instrument shows good correlations with several scales of other relevant QoL instruments. The scales "Initiative Power and Interest", "Social Interaction", "Mental Balance", "Motility", "Physical Complaints", "Digestive Well-Being" sufficiently differentiate the diagnostic groups, particularly between the patients suffering on connective tissue and soft tissue disorders from those with metabolic and nutritional disorders or hypersensitivity reactions. Conclusion Both the factorial validation and the development of a consistent short-form of the HLQ are important steps forward for researchers in the field of QoL who wish to use the HLQ as a reliable and valid instrument. The results indicate that the HLQ is a unique QoL-instrument that can be used for both in-patient and out-patient-treatment. However, to improve to profile of the HLQ, there is still the need for strengthening the Questionnaire in the dimensions of physical well-being. This is the subject of a separate ongoing study. PMID:16004612
Nonlinear static and dynamic analysis of beam structures using fully intrinsic equations
NASA Astrophysics Data System (ADS)
Sotoudeh, Zahra
2011-07-01
Beams are structural members with one dimension much larger than the other two. Examples of beams include propeller blades, helicopter rotor blades, and high aspect-ratio aircraft wings in aerospace engineering; shafts and wind turbine blades in mechanical engineering; towers, highways and bridges in civil engineering; and DNA modeling in biomedical engineering. Beam analysis includes two sets of equations: a generally linear two-dimensional problem over the cross-sectional plane and a nonlinear, global one-dimensional analysis. This research work deals with a relatively new set of equations for one-dimensional beam analysis, namely the so-called fully intrinsic equations. Fully intrinsic equations comprise a set of geometrically exact, nonlinear, first-order partial differential equations that is suitable for analyzing initially curved and twisted anisotropic beams. A fully intrinsic formulation is devoid of displacement and rotation variables, making it especially attractive because of the absence of singularities, infinite-degree nonlinearities, and other undesirable features associated with finite rotation variables. In spite of the advantages of these equations, using them with certain boundary conditions presents significant challenges. This research work will take a broad look at these challenges of modeling various boundary conditions when using the fully intrinsic equations. Hopefully it will clear the path for wider and easier use of the fully intrinsic equations in future research. This work also includes application of fully intrinsic equations in structural analysis of joined-wing aircraft, different rotor blade configuration and LCO analysis of HALE aircraft.
NASA Technical Reports Server (NTRS)
Collins, Emmanuel G., Jr.; Richter, Stephen
1990-01-01
One well known deficiency of LQG compensators is that they do not guarantee any measure of robustness. This deficiency is especially highlighted when considering control design for complex systems such as flexible structures. There has thus been a need to generalize LQG theory to incorporate robustness constraints. Here we describe the maximum entropy approach to robust control design for flexible structures, a generalization of LQG theory, pioneered by Hyland, which has proved useful in practice. The design equations consist of a set of coupled Riccati and Lyapunov equations. A homotopy algorithm that is used to solve these design equations is presented.
The abundant symmetry structure of hierarchies of nonlinear equations obtained by reciprocal links
NASA Astrophysics Data System (ADS)
Carillo, Sandra; Fuchssteiner, Benno
1989-07-01
Explicit computation for a Kawamoto-type equation shows that there is a rich associated symmetry structure for four separate hierarchies of nonlinear integrodifferential equations. Contrary to the general belief that symmetry groups for nonlinear evolution equations in 1+1 dimensions have to be Abelian, it is shown that, in this case, the symmetry group is noncommutative. Its semisimple part is isomorphic to the affine Lie algebra A(1)1 associated to sl(2,C). In two of the additional hierarchies that were found, an explicit dependence of the independent variable occurs. Surprisingly, the generic invariance for the Kawamoto-type equation obtained in Rogers and Carillo [Phys. Scr. 36, 865 (1987)] via a reciprocal link to the Möbius invariance of the singularity equation of the Kaup-Kupershmidt (KK) equation only holds for one of the additional hierarchies of symmetry groups. Thus the generic invariance is not a universal property for the complete symmetry group of equations obtained by reciprocal links. In addition to these results, the bi-Hamiltonian formulation of the hierarchy is given. A direct Bäcklund transformation between the (KK) hierarchy and the hierarchy of singularity equation for the Caudrey-Dodd-Gibbon-Sawada-Kotera equation is exhibited: This shows that the abundant symmetry structure found for the Kawamoto equation must exist for all fifth-order equations, which are known to be completely integrable since these equations are connected either by Bäcklund transformations or reciprocal links. It is shown that similar results must hold for all hierarchies emerging out of singularity hierarchies via reciprocal links. Furthermore, general aspects of the results are discussed.
Structural equation modeling of mediation and moderation with contextual factors
Little, Todd D.; Card, N. A.; Bovaird, James A.; Preacher, Kristopher J.; Crandall, C. S.
2007-01-01
2 X 2 + b 3 X 3 + b 4 W 1 + b 5 W 2 + b 6 W 3 + e x1w1 . (3) For each regression, the residuals of the prediction (e.g., e x1w1 from equation 3) would be saved as a new variable in the dataset (e.g., o X 1 W 1 ,whereo denotes the fact... that share a common indicator in their composition should be allowed to correlate. For example, o X 1 W 1 should be allowed to correlate with each product indicator that shares X 1 and each product indicator that shares W 1 . That is, because o X 1 W 1...
Structural Equation Modeling of Paired-Comparison and Ranking Data
ERIC Educational Resources Information Center
Maydeu-Olivares, Albert; Bockenholt, Ulf
2005-01-01
L. L. Thurstone's (1927) model provides a powerful framework for modeling individual differences in choice behavior. An overview of Thurstonian models for comparative data is provided, including the classical Case V and Case III models as well as more general choice models with unrestricted and factor-analytic covariance structures. A flow chart…
NASA Technical Reports Server (NTRS)
Taylor, Lawrence W., Jr.; Rajiyah, H.
1991-01-01
Partial differential equations for modeling the structural dynamics and control systems of flexible spacecraft are applied here in order to facilitate systems analysis and optimization of these spacecraft. Example applications are given, including the structural dynamics of SCOLE, the Solar Array Flight Experiment, the Mini-MAST truss, and the LACE satellite. The development of related software is briefly addressed.
Fitting Data to Model: Structural Equation Modeling Diagnosis Using Two Scatter Plots
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Hayashi, Kentaro
2010-01-01
This article introduces two simple scatter plots for model diagnosis in structural equation modeling. One plot contrasts a residual-based M-distance of the structural model with the M-distance for the factor score. It contains information on outliers, good leverage observations, bad leverage observations, and normal cases. The other plot contrasts…
ERIC Educational Resources Information Center
Wasserman, Nicholas H.
2014-01-01
Algebraic structures are a necessary aspect of algebraic thinking for K-12 students and teachers. An approach for introducing the algebraic structure of groups and fields through the arithmetic properties required for solving simple equations is summarized; the collective (not individual) importance of these axioms as a foundation for algebraic…
ERIC Educational Resources Information Center
Kim, Young-Mi; Neff, James Alan
2010-01-01
A model incorporating the direct and indirect effects of parental monitoring on adolescent alcohol use was evaluated by applying structural equation modeling (SEM) techniques to data on 4,765 tenth-graders in the 2001 Monitoring the Future Study. Analyses indicated good fit of hypothesized measurement and structural models. Analyses supported both…
OpenMx: An Open Source Extended Structural Equation Modeling Framework
ERIC Educational Resources Information Center
Boker, Steven; Neale, Michael; Maes, Hermine; Wilde, Michael; Spiegel, Michael; Brick, Timothy; Spies, Jeffrey; Estabrook, Ryne; Kenny, Sarah; Bates, Timothy; Mehta, Paras; Fox, John
2011-01-01
OpenMx is free, full-featured, open source, structural equation modeling (SEM) software. OpenMx runs within the "R" statistical programming environment on Windows, Mac OS-X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced--these…
ERIC Educational Resources Information Center
Goldstein, Harvey; Bonnet, Gerard; Rocher, Thierry
2007-01-01
The Programme for International Student Assessment comparative study of reading performance among 15-year-olds is reanalyzed using statistical procedures that allow the full complexity of the data structures to be explored. The article extends existing multilevel factor analysis and structural equation models and shows how this can extract richer…
Application of Exploratory Structural Equation Modeling to Evaluate the Academic Motivation Scale
ERIC Educational Resources Information Center
Guay, Frédéric; Morin, Alexandre J. S.; Litalien, David; Valois, Pierre; Vallerand, Robert J.
2015-01-01
In this research, the authors examined the construct validity of scores of the Academic Motivation Scale using exploratory structural equation modeling. Study 1 and Study 2 involved 1,416 college students and 4,498 high school students, respectively. First, results of both studies indicated that the factor structure tested with exploratory…
On the multi-symplectic structure of the Serre-Green-Naghdi equations
Chhay, Marx; Clamond, Didier
2015-01-01
In this short note, we present a multi-symplectic structure of the Serre-Green-Naghdi (SGN) equations modelling nonlinear long surface waves in shallow water. This multi-symplectic structure allow the use of efficient finite difference or pseudo-spectral numerical schemes preserving exactly the multi-symplectic form at the discrete level.
Structural Equation Modeling in Assessing Students' Understanding of the State Changes of Matter
ERIC Educational Resources Information Center
Stamovlasis, Dimitrios; Tsitsipis, Georgios; Papageorgiou, George
2012-01-01
In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of the particulate nature of matter, the collective properties and physical changes, such as melting, evaporation, boiling and condensation. The structural relationships among particular groups of items were investigated. In addition,…
Basu, Abhik; Naji, Ali; Pandit, Rahul
2014-01-01
We generalize the method of A. M. Polyakov, [ Phys. Rev. E 52 6183 (1995)] for obtaining structure-function relations in turbulence in the stochastically forced Burgers equation, to develop structure-function hierarchies for turbulence in three models for magnetohydrodynamics (MHD). These are the Burgers analogs of MHD in one dimension [ Eur. Phys. J. B 9 725 (1999)], and in three dimensions (3DMHD and 3D Hall MHD). Our study provides a convenient and unified scheme for the development of structure-function hierarchies for turbulence in a variety of coupled hydrodynamical equations. For turbulence in the three sets of MHD equations mentioned above, we obtain exact relations for third-order structure functions and their derivatives; these expressions are the analogs of the von Kármán-Howarth relations for fluid turbulence. We compare our work with earlier studies of such relations in 3DMHD and 3D Hall MHD. PMID:24580182
NASA Technical Reports Server (NTRS)
Park, K. C.; Alvin, K. F.; Belvin, W. Keith
1991-01-01
A second-order form of discrete Kalman filtering equations is proposed as a candidate state estimator for efficient simulations of control-structure interactions in coupled physical coordinate configurations as opposed to decoupled modal coordinates. The resulting matrix equation of the present state estimator consists of the same symmetric, sparse N x N coupled matrices of the governing structural dynamics equations as opposed to unsymmetric 2N x 2N state space-based estimators. Thus, in addition to substantial computational efficiency improvement, the present estimator can be applied to control-structure design optimization for which the physical coordinates associated with the mass, damping and stiffness matrices of the structure are needed instead of modal coordinates.
Recursion operators and bi-Hamiltonian structure of the general heavenly equation
Sheftel, M B; Yaz?c?, D
2015-01-01
We discover two additional Lax pairs and three nonlocal recursion operators for symmetries of the general heavenly equation introduced by Doubrov and Ferapontov. Converting the equation to a two-component form, we obtain Lagrangian and Hamiltonian structures of the two-component general heavenly system. We study all point symmetries of the two-component system and, using the inverse Noether theorem in the Hamiltonian form, obtain all the integrals of motion corresponding to each variational (Noether) symmetry. We discover that all the recursion operators coincide in the two-component form. Applying the recursion operator to the first Hamiltonian structure we obtain second Hamiltonian structure. We prove the Jacobi identities for the second Hamiltonian operator and compatibility of the two Hamiltonian structures. Thus, we demonstrate that the general heavenly equation in the two-component form is a bi-Hamiltonian system integrable in the sense of Magri. We demonstrate how to obtain nonlocal Hamiltonian flows g...
ERIC Educational Resources Information Center
Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.
This questionnaire assesses drug use practices in junior and senior high school students. The 21 multiple choice items pertain to drug use practices, use history, available of drugs, main reason for drug use, and demographic data. The questionnaire is untimed, group administered, and may be given by the classroom teacher in about 10 minutes. Item…
ERIC Educational Resources Information Center
Cook, David I.
1975-01-01
Contends that student evaluative questionnaires should be designed by instructors themselves to help improve their classroom performance and therefore should contain only questions that students are capable of answering objectively and not, for instance, questions about the relevancy of the course. Contains a sample questionnaire. (GH)
Creswell, Kasey G.; Chung, Tammy; Wright, Aidan G. C.; Clark, Duncan B.; Black, Jessica J.; Martin, Christopher S.
2015-01-01
Aims This study examined the personality traits of negative emotionality and constraint and the ability to resist drinking during negative affective states as correlates of solitary drinking in adolescence. We hypothesized that higher levels of negative emotionality and lower levels of constraint would predict solitary drinking and that these relationships would be mediated by the ability to resist drinking in response to negative emotions. Design Structural equation modeling was used to fit a path model from the personality traits of negative emotionality and constraint to solitary drinking status through intermediate effects on the ability to resist drinking during negative emotions using cross-sectional data. Setting Clinical and community settings in Pennsylvania, USA. Participants The sample included 761 adolescent drinkers (mean age = 17.1). Measurements Adolescents completed the Lifetime Drinking History, the Multidimensional Personality Questionnaire, the Constructive Thinking Inventory and the Situational Confidence Questionnaire. Findings The path model provided a good fit to the data. The association between trait negative emotionality and solitary drinking was fully mediated by adolescents' ability to resist drinking during negative affective states (b = 0.05, P = 0.01). In contrast, constraint had a direct effect on solitary drinking (odds ratio (OR) = 0.79, b = –0.23, P<0.01), as well as an indirect effect through the ability to resist drinking during negative affective states (b = –0.03, P = 0.02). Conclusions The ability to resist drinking while experiencing negative feelings or emotions may be an important underlying mechanism linking trait negative emotionality (a tendency toward depression, anxiety and poor reaction to stress) and constraint (lack of impulsiveness) to adolescent solitary drinking. PMID:25664806
Stone, D H
1993-01-01
The design of questionnaires is a craft which has been badly neglected by the medical profession. A questionnaire should be appropriate, intelligible, unambiguous, unbiased, capable of coping with all possible responses, satisfactorily coded, piloted, and ethical. The key steps in designing a questionnaire are to: decide what data you need, select items for inclusion, design the individual questions, compose the wording, design the layout and presentation, think about coding, prepare the first draft and pretest, pilot, and evaluate the form, and perform the survey. Despite the apparently complicated nature of the task, theoretical knowledge is no substitute for practical experience. PMID:8281062
Wang, Jong-Yi; Liang, Wen-Miin; Yang, Tung-Chuan; Lee, Young-Chang; Wang, Chia-Woei
2015-01-01
Objective Patients with infertility are a high risk group in depression and anxiety. However, an existing theoretically and empirically validated model of stressors, stress, and mental symptoms specific for infertile patients is still a void. This study aimed to determine the related factors and their relational structures that affect the level of depressive and anxiety symptoms among infertile patients. Methods A cross-sectional sample of 400 infertility outpatients seeking reproduction treatments in three teaching hospitals across Taiwan participated in the structured questionnaire survey in 2011. The hypothesized model comprising 10 latent variables was tested by Structural Equation Modeling using AMOS 17. Results Goodness-of-fit indexes, including ?2/DF = 1.871, PGFI = 0.746, PNFI = 0.764, and others, confirmed the modified model fit the data well. Marital stressor, importance of children, guilt-and-blame, and social stressor showed a direct effect on perceived stress. Instead of being a factor of stress, social support was directly and positively related to self-esteem. Perceived stress and self-esteem were the two major mediators for the relationships between stressors and mental symptoms. Increase in social support and self-esteem led to decrease in mental symptoms among the infertile patients. Conclusions The relational structures were identified and named as the Stressors Stress Symptoms Model, clinically applied to predict anxiety and depression from various stressors. Assessing sources and level of infertility-related stress and implementing culturally-sensitive counseling with an emphasis on positive personal value may assist in preventing the severity of depression and anxiety. PMID:26484531
Second-order discrete Kalman filtering equations for control-structure interaction simulations
NASA Technical Reports Server (NTRS)
Park, K. C.; Belvin, W. Keith; Alvin, Kenneth F.
1991-01-01
A general form for the first-order representation of the continuous, second-order linear structural dynamics equations is introduced in order to derive a corresponding form of first-order Kalman filtering equations (KFE). Time integration of the resulting first-order KFE is carried out via a set of linear multistep integration formulas. It is shown that a judicious combined selection of computational paths and the undetermined matrices introduced in the general form of the first-order linear structural systems leads to a class of second-order discrete KFE involving only symmetric, N x N solution matrix.
The Environmental Satisfaction Questionnaire
ERIC Educational Resources Information Center
Corazzini, John G.; And Others
1977-01-01
The Environmental Satisfaction Questionnaire (ESQ) is an instrument that has been developed to provide assessment information which can be used for redesign purposes. The article includes an explanation of the technology of the ESQ and several examples. (Author)
NASA Technical Reports Server (NTRS)
Thorne, K. S.; Zytkow, A. N.
1976-01-01
The general relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general relativistic version of the mixing-length formalism for convection is presented. Finally, it is argued that in previous work on spherical systems general relativity theorists have identified the wrong quantity as "total mass-energy inside radius r."
McGuire, Brian E.; Morrison, Todd G.; Barker, Lynne A.; Morton, Nicholas; McBrinn, Judith; Caldwell, Sheena; Wilson, Colin F.; McCann, John; Carton, Simone; Delargy, Mark; Walsh, Jane
2014-01-01
Aims: This study sought to address two questions: (1) what is the inter-rater reliability of the Dysexecutive Questionnaire (DEX) when completed by patients, their significant others, and clinicians; and (2) does the factor structure of the DEX vary for these three groups? Methods: We obtained DEX ratings for 113 patients with an acquired brain injury from two brain injury services in the UK and two services in Ireland. We gathered data from two groups of raters—“significant others” (DEX-SO) such as partners and close family members and “clinicians” (DEX-C), who were psychologists or rehabilitation physicians working closely with the patient and who were able to provide an opinion about the patient’s level of everyday executive functioning. Intra-class correlation coefficients and their 95% confidence intervals were calculated between each of the three groups (self, significant other, clinician). Principal axis factor (PAF) analyses were also conducted for each of the three groups. Results: The factor analysis revealed a consistent one-factor model for each of the three groups of raters. However, the inter-rater reliability analyses showed a low level of agreement between the self-ratings and the ratings of the two groups of independent raters. We also found low agreement between the significant others and the clinicians. Conclusion: Although there was a consistent finding of a single factor solution for each of the three groups, the low level of agreement between significant others and clinicians raises a question about the reliability of the DEX. PMID:25346668
An analysis of the vertical structure equation for arbitrary thermal profiles
NASA Technical Reports Server (NTRS)
Cohn, Stephen E.; Dee, Dick P.
1989-01-01
The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.
An analysis of the vertical structure equation for arbitrary thermal profiles
NASA Technical Reports Server (NTRS)
Cohn, Stephen E.; Dee, Dick P.
1987-01-01
The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.
Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory
Aupic, Jana; Urbic, Tomaz
2014-05-14
Monte Carlo simulations and integral equation theory were used to predict the thermodynamics and structure of a two-dimensional Coulomb fluid. We checked the possibility that integral equations reproduce Kosterlitz-Thouless and vapor-liquid phase transitions of the electrolyte and critical points. Integral equation theory results were compared to Monte Carlo data and the correctness of selected closure relations was assessed. Among selected closures hypernetted-chain approximation results matched computer simulation data best, but these equations unfortunately break down at temperatures well above the Kosterlitz-Thouless transition. The Kovalenko-Hirata closure produces results even at very low temperatures and densities, but no sign of phase transition was detected.
Gunzler, Douglas D; Morris, Nathan
2015-10-30
Structural equation modeling (SEM) is a very general approach to analyzing data in the presence of measurement error and complex causal relationships. In this tutorial, we describe SEM, with special attention to exploratory factor analysis, confirmatory factor analysis, and multiple indicator multiple cause modeling. The tutorial is motivated by a problem of symptom overlap routinely faced by clinicians and researchers, in which symptoms or test results are common to two or more co-occurring conditions. As a result of such overlap, diagnoses, treatment decisions, and inferences about the effectiveness of treatments for these conditions can be biased. This problem is further complicated by increasing reliance on patient-reported outcomes, which introduces systematic error based on an individual's interpretation of a test questionnaire. SEM provides flexibility in handling this type of differential item functioning and disentangling the overlap. Scales and scoring approaches can be revised to be free of this overlap, leading to better care. This tutorial uses an example of depression screening in multiple sclerosis patients in which depressive symptoms overlap with other symptoms, such as fatigue, cognitive impairment, and functional impairment. Details of how MPlus (Muthén & Muthén, Los Angeles,?CA, USA) software can be used to address the symptom overlap problem, including data requirements, code and output are described in this tutorial. Copyright © 2015?John Wiley & Sons, Ltd. PMID:26045102
NASA Astrophysics Data System (ADS)
Velayutham, Sunitadevi; Aldridge, Jill M.
2013-04-01
The primary aim of this study was two-fold: 1) to identify salient psychosocial features of the classroom environment that influence students' motivation and self-regulation in science learning; and 2) to examine the effect of the motivational constructs of learning goal orientation, science task value and self-efficacy in science learning on students' self-regulation in science classrooms. Data collected from 1360 science students in grades 8, 9 and 10 in five public schools in Perth, Western Australia were utilized to validate the questionnaires and to investigate the hypothesized relationships. Structural Equation Modeling analysis suggested that student cohesiveness, investigation and task orientation were the most influential predictors of student motivation and self-regulation in science learning. In addition, learning goal orientation, task value and self-efficacy significantly influenced students' self-regulation in science. The findings offer potential opportunities for educators to plan and implement effective pedagogical strategies aimed at increasing students' motivation and self-regulation in science learning.
Questioning Newton's second law: What is the structure of equations of motion?
Claus Lämmerzahl; Patricia Rademaker
2009-04-30
Interactions are explored through the observation of the dynamics of particles. On the classical level the basic underlying assumption in that scheme is that Newton's second law holds. Relaxing the validity of this axiom by, e.g., allowing for higher order time derivatives in the equations of motion would allow for a more general structure of interactions. We derive the structure of interactions by means of a gauge principle and discuss the physics emerging from equations of motion of higher order. One main result is higher order derivatives induce a zitterbewegung. As a consequence the main motion resulting from the second order equation of motion is rather robust against modifications. The gauge principle leads to a gauge field with the property of a space metric. We confront this general scheme with experimental data.
Questioning Newton's second law: What is the structure of equations of motion?
Lämmerzahl, Claus
2009-01-01
Interactions are explored through the observation of the dynamics of particles. On the classical level the basic underlying assumption in that scheme is that Newton's second law holds. Relaxing the validity of this axiom by, e.g., allowing for higher order time derivatives in the equations of motion would allow for a more general structure of interactions. We derive the structure of interactions by means of a gauge principle and discuss the physics emerging from equations of motion of higher order. One main result is higher order derivatives induce a zitterbewegung. As a consequence the main motion resulting from the second order equation of motion is rather robust against modifications. The gauge principle leads to a gauge field with the property of a space metric. We confront this general scheme with experimental data.
ERIC Educational Resources Information Center
Zhang, Dongbo
2012-01-01
Using structural equation modeling analysis, this study examined the contribution of vocabulary and grammatical knowledge to second language reading comprehension among 190 advanced Chinese English as a foreign language learners. Vocabulary knowledge was measured in both breadth (Vocabulary Levels Test) and depth (Word Associates Test);…
Prescriptive Statements and Educational Practice: What Can Structural Equation Modeling (SEM) Offer?
ERIC Educational Resources Information Center
Martin, Andrew J.
2011-01-01
Longitudinal structural equation modeling (SEM) can be a basis for making prescriptive statements on educational practice and offers yields over "traditional" statistical techniques under the general linear model. The extent to which prescriptive statements can be made will rely on the appropriate accommodation of key elements of research design,…
A Structural Equation Modelling of the Academic Self-Concept Scale
ERIC Educational Resources Information Center
Matovu, Musa
2014-01-01
The study aimed at validating the academic self-concept scale by Liu and Wang (2005) in measuring academic self-concept among university students. Structural equation modelling was used to validate the scale which was composed of two subscales; academic confidence and academic effort. The study was conducted on university students; males and…
ERIC Educational Resources Information Center
Hill, P. W.
1984-01-01
The use of structural equation modeling is discussed in testing a range of theories of learning and cognition involving the concept of a hierarchy of variables of increasing complexity. To illustrate this approach, one method is applied to Bloom's taxonomy to test the theoretical assumption of hierarchical organization. (Author/MSE)
Band structure analysis of an analytically solvable Hill equation with continuous potential
NASA Astrophysics Data System (ADS)
Morozov, G. V.; Sprung, D. W. L.
2015-03-01
This paper concerns analytically solvable cases of Hill’s equation containing a continuously differentiable periodic potential. We outline a procedure for constructing the Floquet-Bloch fundamental system, and analyze the band structure of the system. The similarities to, and differences from, the cases of a piecewise constant periodic potential and the Mathieu potential, are illuminated.
The Effect of Varying Degrees of Nonnormality in Structural Equation Modeling
ERIC Educational Resources Information Center
Lei, Ming; Lomax, Richard G.
2005-01-01
This simulation study investigated the robustness of structural equation modeling to different degrees of nonnormality under 2 estimation methods, generalized least squares and maximum likelihood, and 4 sample sizes, 100, 250, 500, and 1,000. Each of the slight and severe nonnormality degrees was comprised of pure skewness, pure kurtosis, and both…
ERIC Educational Resources Information Center
Budsankom, Prayoonsri; Sawangboon, Tatsirin; Damrongpanit, Suntorapot; Chuensirimongkol, Jariya
2015-01-01
The purpose of the research is to develop and identify the validity of factors affecting higher order thinking skills (HOTS) of students. The thinking skills can be divided into three types: analytical, critical, and creative thinking. This analysis is done by applying the meta-analytic structural equation modeling (MASEM) based on a database of…
The Relation among Fit Indexes, Power, and Sample Size in Structural Equation Modeling
ERIC Educational Resources Information Center
Kim, Kevin H.
2005-01-01
The relation among fit indexes, power, and sample size in structural equation modeling is examined. The noncentrality parameter is required to compute power. The 2 existing methods of computing power have estimated the noncentrality parameter by specifying an alternative hypothesis or alternative fit. These methods cannot be implemented easily and…
Spiritual Leadership and Organizational Culture: A Study of Structural Equation Modeling
ERIC Educational Resources Information Center
Karadag, Engin
2009-01-01
The aim of this study is to test the spiritual leadership behaviors of school principles in a structural equation model. The study is designed to test causality with the assumption that causality exists between the two variables. In this study, spiritual leadership behavior of managers is treated as the independent variable whereas the…
ERIC Educational Resources Information Center
Celik, Eyup; Arici, Neslihan
2014-01-01
This study aimed to predict the effects of levels of sexual awareness, sexual courage, and sexual self-disclosure on sexual embarrassment. Data was collected from 336 married individuals, who have students in the Sultangazi District of Istanbul. According to the structural equation model (SEM), sexual self-disclosure, directly, and sexual courage…
ERIC Educational Resources Information Center
Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.
2013-01-01
Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…
Structural Equation Modeling in Language Testing and Learning Research: A Review
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2011-01-01
Despite the recent increase of structural equation modeling (SEM) in language testing and learning research and Kunnan's (1998) call for the proper use of SEM to produce useful findings, there seem to be no reviews about how SEM is applied in these areas or about the extent to which the current application accords with appropriate practices. To…
An Application of Structural Equation Modeling for Developing Good Teaching Characteristics Ontology
ERIC Educational Resources Information Center
Phiakoksong, Somjin; Niwattanakul, Suphakit; Angskun, Thara
2013-01-01
Ontology is a knowledge representation technique which aims to make knowledge explicit by defining the core concepts and their relationships. The Structural Equation Modeling (SEM) is a statistical technique which aims to explore the core factors from empirical data and estimates the relationship between these factors. This article presents an…
ERIC Educational Resources Information Center
Johnson, Jennifer E.; Burlingame, Gary M.; Olsen, Joseph A.; Davies, D. Robert; Gleave, Robert L.
2005-01-01
This study examined the definitional and statistical overlap among 4 key group therapeutic relationship constructs--group climate, cohesion, alliance, and empathy--across member-member, member-group, and member-leader relationships. Three multilevel structural equation models were tested using self-report measures completed by 662 participants…
ERIC Educational Resources Information Center
Karadag, Engin; Kilicoglu, Gökhan; Yilmaz, Derya
2014-01-01
The purpose of this study is to explain constructed theoretical models that organizational cynicism perceptions of primary school teachers affect school culture and academic achievement, by using structural equation modeling. With the assumption that there is a cause-effect relationship between three main variables, the study was constructed with…
ERIC Educational Resources Information Center
Chen, Wei; Wang, Long; Zhang, Xing-Li; Shi, Jian-Nong
2012-01-01
The objective of this study was to investigate the impact of trauma exposure on the posttraumatic stress symptomatology (PTSS) of children who resided near the epicenter of the 2008 Wenchuan earthquake. The mechanisms of this impact were explored via structural equation models with self-esteem and coping strategies included as mediators. The…
ERIC Educational Resources Information Center
Li, Spencer D.
2011-01-01
Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the…
COHERENT STRUCTURES AND CARRIER SHOCKS IN THE NONLINEAR PERIODIC MAXWELL EQUATIONS
Simpson, Gideon
.1. Nonlinear geometric optics expansion 14 4.2. Periodic Media and xNLCME 16 4.3. Conservation Laws2010 #12;periodic and nonlinear constituitive laws. This paper explores a class of nonlinear hyperbolicCOHERENT STRUCTURES AND CARRIER SHOCKS IN THE NONLINEAR PERIODIC MAXWELL EQUATIONS GIDEON SIMPSON
ERIC Educational Resources Information Center
Wang, Jing-Ru; Chen, Shin-Feng
2014-01-01
This study used a Chinese-language version of the Index of Science Reading Awareness (ISRA) to investigate metacognitive awareness and the Reading Comprehension of Science Test (RCST) to explore comprehension of science text by Taiwanese students. Structural equation modeling (SEM) results confirmed the validity of the underlying models of…
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2010-01-01
Because structural equation models are widely used in testing and assessment, investigation into the accuracy of such models may help raise awareness of the value of reanalysis or replication. We focused on second language testing and learning studies and examined: (a) To what extent is information necessary for replication provided by authors?…
ERIC Educational Resources Information Center
Bollen, Kenneth A.; Maydeu-Olivares, Albert
2007-01-01
This paper presents a new polychoric instrumental variable (PIV) estimator to use in structural equation models (SEMs) with categorical observed variables. The PIV estimator is a generalization of Bollen's (Psychometrika 61:109-121, 1996) 2SLS/IV estimator for continuous variables to categorical endogenous variables. We derive the PIV estimator…
Bias and Efficiency in Structural Equation Modeling: Maximum Likelihood versus Robust Methods
ERIC Educational Resources Information Center
Zhong, Xiaoling; Yuan, Ke-Hai
2011-01-01
In the structural equation modeling literature, the normal-distribution-based maximum likelihood (ML) method is most widely used, partly because the resulting estimator is claimed to be asymptotically unbiased and most efficient. However, this may not hold when data deviate from normal distribution. Outlying cases or nonnormally distributed data,…
ERIC Educational Resources Information Center
Green, Samuel B.; Yang, Yanyun
2009-01-01
A method is presented for estimating reliability using structural equation modeling (SEM) that allows for nonlinearity between factors and item scores. Assuming the focus is on consistency of summed item scores, this method for estimating reliability is preferred to those based on linear SEM models and to the most commonly reported estimate of…
Using Structural Equation Modeling to Improve Research in Career and Technical Education
ERIC Educational Resources Information Center
Kim, Heeja; Rojewski, Jay W.
2002-01-01
This paper describes structural equation modeling (SEM) and possibilities for using SEM to address problems specific to workforce education and career development. A sample of adolescents identified as work-bound (i.e., transition directly from secondary school to work) from the National Education Longitudinal Study 1988-1996 database (NELS:…
Performance and scaling of locally-structured grid methods forpartial differential equations
Colella, Phillip; Bell, John; Keen, Noel; Ligocki, Terry; Lijewski, Michael; Van Straalen, Brian
2007-07-19
In this paper, we discuss some of the issues in obtaining high performance for block-structured adaptive mesh refinement software for partial differential equations. We show examples in which AMR scales to thousands of processors. We also discuss a number of metrics for performance and scalability that can provide a basis for understanding the advantages and disadvantages of this approach.
Residuals and the Residual-Based Statistic for Testing Goodness of Fit of Structural Equation Models
ERIC Educational Resources Information Center
Foldnes, Njal; Foss, Tron; Olsson, Ulf Henning
2012-01-01
The residuals obtained from fitting a structural equation model are crucial ingredients in obtaining chi-square goodness-of-fit statistics for the model. The authors present a didactic discussion of the residuals, obtaining a geometrical interpretation by recognizing the residuals as the result of oblique projections. This sheds light on the…
Anti-Transgender Prejudice: A Structural Equation Model of Associated Constructs
ERIC Educational Resources Information Center
Tebbe, Esther N.; Moradi, Bonnie
2012-01-01
This study aimed to identify theoretically relevant key correlates of anti-transgender prejudice. Specifically, structural equation modeling was used to test the unique relations of anti-lesbian, gay, and bisexual (LGB) prejudice; traditional gender role attitudes; need for closure; and social dominance orientation with anti-transgender prejudice.…
Self-Conscious Emotions in Response to Perceived Failure: A Structural Equation Model
ERIC Educational Resources Information Center
Bidjerano, Temi
2010-01-01
This study explored the occurrence of self-conscious emotions in response to perceived academic failure among 4th-grade students from the United States and Bulgaria, and the author investigated potential contributors to such negative emotional experiences. Results from structural equation modeling indicated that regardless of country, negative…
ERIC Educational Resources Information Center
Enders, Craig K.; Bandalos, Deborah L.
2001-01-01
Used Monte Carlo simulation to examine the performance of four missing data methods in structural equation models: (1)full information maximum likelihood (FIML); (2) listwise deletion; (3) pairwise deletion; and (4) similar response pattern imputation. Results show that FIML estimation is superior across all conditions of the design. (SLD)
Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling
ERIC Educational Resources Information Center
Nevitt, Jonathan; Hancock, Gregory R.
2004-01-01
Through Monte Carlo simulation, small sample methods for evaluating overall data-model fit in structural equation modeling were explored. Type I error behavior and power were examined using maximum likelihood (ML), Satorra-Bentler scaled and adjusted (SB; Satorra & Bentler, 1988, 1994), residual-based (Browne, 1984), and asymptotically…
Evaluating Small Sample Approaches for Model Test Statistics in Structural Equation Modeling.
ERIC Educational Resources Information Center
Nevitt, Jonathan
Structural equation modeling (SEM) attempts to remove the negative influence of measurement error and allows for investigation of relationships at the level of the underlying constructs of interest. SEM has been regarded as a "large sample" technique since its inception. Recent developments in SEM, some of which are currently available in popular…
ERIC Educational Resources Information Center
Eid, Michael; Nussbeck, Fridtjof W.; Geiser, Christian; Cole, David A.; Gollwitzer, Mario; Lischetzke, Tanja
2008-01-01
The question as to which structural equation model should be selected when multitrait-multimethod (MTMM) data are analyzed is of interest to many researchers. In the past, attempts to find a well-fitting model have often been data-driven and highly arbitrary. In the present article, the authors argue that the measurement design (type of methods…
ERIC Educational Resources Information Center
MacIntosh, Randall
1997-01-01
Presents KANT, a FORTRAN 77 software program that tests assumptions of multivariate normality in a data set. Based on the test developed by M. V. Mardia (1985), the KANT program is useful for those engaged in structural equation modeling with latent variables. (SLD)
ERIC Educational Resources Information Center
Bechger, Timo M.; Maris, Gunter
2004-01-01
This paper is about the structural equation modelling of quantitative measures that are obtained from a multiple facet design. A facet is simply a set consisting of a finite number of elements. It is assumed that measures are obtained by combining each element of each facet. Methods and traits are two such facets, and a multitrait-multimethod…
Bayesian Structural Equation Modeling: A More Flexible Representation of Substantive Theory
ERIC Educational Resources Information Center
Muthen, Bengt; Asparouhov, Tihomir
2012-01-01
This article proposes a new approach to factor analysis and structural equation modeling using Bayesian analysis. The new approach replaces parameter specifications of exact zeros with approximate zeros based on informative, small-variance priors. It is argued that this produces an analysis that better reflects substantive theories. The proposed…
ERIC Educational Resources Information Center
Chen, Ying-Chieh; Li, Ren-Hau; Chen, Sheng-Hwang
2013-01-01
The purpose of this cross-sectional study was to test a cause-and-effect model of factors affecting leisure satisfaction among Taiwanese adolescents. A structural equation model was proposed in which the relationships among leisure motivation, leisure involvement, and leisure satisfaction were explored. The study collected data from 701 adolescent…
ERIC Educational Resources Information Center
Kim, Minkee; Song, Jinwoong
2010-01-01
Many models in science education have tried to clarify the causal relationships of affective variables on student performance, by presenting theoretical models, exploratory SEM (structural equation models), and confirmatory SEM. Based on the literature, the recent AS-TI-CU model scrutinised the most robust stimuli of conceptual understanding (CU):…
NONLINEAR WAVE EQUATIONS ARISING IN MODELING OF SOME STRAIN-HARDENING STRUCTURES
Wei, Dongming
NONLINEAR WAVE EQUATIONS ARISING IN MODELING OF SOME STRAIN-HARDENING STRUCTURES DONGMING WEI crashworthy vehicles. These metals are special cases of nonlinear strain-hardening elastic-plastic materials on the heat treatment received by the metal or alloy. The parameter n is called the strain-hardening exponent
An Examination of Statistical Power in Multigroup Dynamic Structural Equation Models
ERIC Educational Resources Information Center
Prindle, John J.; McArdle, John J.
2012-01-01
This study used statistical simulation to calculate differential statistical power in dynamic structural equation models with groups (as in McArdle & Prindle, 2008). Patterns of between-group differences were simulated to provide insight into how model parameters influence power approximations. Chi-square and root mean square error of…
ERIC Educational Resources Information Center
Tokar, David M.; Withrow, Jason R.; Hall, Rosalie J.; Moradi, Bonnie
2003-01-01
Structural equation modeling was used to test theoretically based models in which psychological separation and attachment security variables were related to career indecision and those relations were mediated through vocational self-concept crystallization. Results indicated that some components of separation and attachment security did relate to…
Meta-Analytic Structural Equation Modeling: A Two-Stage Approach
ERIC Educational Resources Information Center
Cheung, Mike W. L.; Chan, Wai
2005-01-01
To synthesize studies that use structural equation modeling (SEM), researchers usually use Pearson correlations (univariate r), Fisher z scores (univariate z), or generalized least squares (GLS) to combine the correlation matrices. The pooled correlation matrix is then analyzed by the use of SEM. Questionable inferences may occur for these ad hoc…
ERIC Educational Resources Information Center
Horzum, Mehmet Baris; Kaymak, Zeliha Demir; Gungoren, Ozlem Canan
2015-01-01
The relationship between online learning readiness, academic motivations, and perceived learning was investigated via structural equation modeling in the research. The population of the research consisted of 750 students who studied using the online learning programs of Sakarya University. 420 of the students who volunteered for the research and…
Blow-up results for vector-valued nonlinear heat equations with no gradient structure
Zaag, Hatem
Blow-up results for vector-valued nonlinear heat equations with no gradient structure Hatem Zaag, nonlinear optics). See for example Levermore and Olivier [15] and the references inside. Blow-up results(t)|H + when t T, we say: u(t) blows-up in finite time T in H. In this paper, we are interested in the finite
ERIC Educational Resources Information Center
Hellle, Laura; Tuijula, Tiina; Laakkonen, Eero
2009-01-01
The purpose of the study is to shed light on the mechanisms behind scholastic achievement in high school by testing a structural equations model based on the work by Vermunt (1998). It was presumed that self-regulation of learning would predict scholastic achievement and that learning orientations would predict self-regulation of learning. A…
A Demonstration of a Systematic Item-Reduction Approach Using Structural Equation Modeling
ERIC Educational Resources Information Center
Larwin, Karen; Harvey, Milton
2012-01-01
Establishing model parsimony is an important component of structural equation modeling (SEM). Unfortunately, little attention has been given to developing systematic procedures to accomplish this goal. To this end, the current study introduces an innovative application of the jackknife approach first presented in Rensvold and Cheung (1999). Unlike…
ERIC Educational Resources Information Center
Raykov, Tenko; Marcoulides, George A.
2006-01-01
A structural equation modeling approach to scale reliability evaluation can be employed to estimate generalizability theory indexes in settings where sampling of subjects and conditions is carried out. In one- and two-facet crossed designs, it is demonstrated how this method can be used to obtain estimates of relative generalizability…
Standards-Based Evaluation and Teacher Career Satisfaction: A Structural Equation Modeling Analysis
ERIC Educational Resources Information Center
Conley, Sharon; Muncey, Donna E.; You, Sukkyung
2005-01-01
Structural equation modeling was used to assess the plausibility of a conceptual model specifying hypothesized linkages among perceptions of characteristics of standards-based evaluation, work environment mediators, and career satisfaction and other outcomes. Four comprehensive high schools located in two neighboring counties in southern…
Giannakis, Georgios
1 Inference of gene regulatory networks with sparse structural equation models exploiting genetic Integrating genetic perturbations with gene expression data not only improves accuracy of regulatory net- work topology inference, but also enables learning of causal regulatory relations between genes. Although
General features and master equations for structurization in complex dusty plasmas
Tsytovich, V. N.; Morfill, G. E.
2012-02-15
Dust structurization is considered to be typical for complex plasmas. Homogeneous dusty plasmas are shown to be universally unstable. The dusty plasma structurization instability is similar to the gravitational instability and can results in creation of different compact dust structures. A general approach for investigation of the nonlinear stage of structurization in dusty plasmas is proposed and master equations for the description of self-organized structures are formulated in the general form that can be used for any nonlinear model of dust screening. New effects due to the scattering of ions on the nonlinearly screened grains are calculated: nonlinear ion dust drag force and nonlinear ion diffusion. The physics of confinement of dust and plasma components in the equilibria of compact dust structures is presented and is supported by numerical calculations of master equations. The necessary conditions for the existence of equilibrium structures are found for an arbitrary nonlinearity in dust screening. Features of compact dust structures observed in recent experiments agree with the numerically calculated ones. Some proposals for future experiments in spherical chamber are given.
Quantization of wave equations and hermitian structures in partial differential varieties.
Paneitz, S M; Segal, I E
1980-12-01
Sufficiently close to 0, the solution variety of a nonlinear relativistic wave equation-e.g., of the form squarevarphi + m(2)varphi + gvarphi(p) = 0-admits a canonical Lorentz-invariant hermitian structure, uniquely determined by the consideration that the action of the differential scattering transformation in each tangent space be unitary. Similar results apply to linear time-dependent equations or to equations in a curved asymptotically flat space-time. A close relation of the Riemannian structure to the determination of vacuum expectation values is developed and illustrated by an explicit determination of a perturbative 2-point function for the case of interaction arising from curvature. The theory underlying these developments is in part a generalization of that of M. G. Krein and collaborators concerning stability of differential equations in Hilbert space and in part a precise relation between the unitarization of given symplectic linear actions and their full probabilistic quantization. The unique causal structure in the infinite symplectic group is instrumental in these developments. PMID:16592923
Ovchinnikov, Yu. N.
2013-09-15
Solutions to the generalized Ginzburg-Landau equations for superconductors are obtained for a Ginzburg-Landau parameter {kappa} close to unity. The families of solutions with arbitrary number n of flux quanta in a unit cell are analyzed. It is shown that under certain conditions, a cascade of phase transitions between different structures in a magnetic field appears near T{sub c}. Algebraic equations are derived for determining the boundaries of coexistence of different phases on the (T, H{sub 0}) plane.
Solution of quadratic matrix equations for free vibration analysis of structures.
NASA Technical Reports Server (NTRS)
Gupta, K. K.
1973-01-01
An efficient digital computer procedure and the related numerical algorithm are presented herein for the solution of quadratic matrix equations associated with free vibration analysis of structures. Such a procedure enables accurate and economical analysis of natural frequencies and associated modes of discretized structures. The numerically stable algorithm is based on the Sturm sequence method, which fully exploits the banded form of associated stiffness and mass matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be substantially more accurate and economical than other existing procedures of such analysis. Numerical examples are presented for two structures - a cantilever beam and a semicircular arch.
Wu, Jiun-Yu
2011-10-21
Conventional statistical methods assuming data sampled under simple random sampling are inadequate for use on complex survey data with a multilevel structure and non-independent observations. In structural equation modeling ...
ERIC Educational Resources Information Center
Yeh, Yu-Chen; Lin, Sunny S. J.; Tseng, Yin-Hsing; Hwang, Fang-Ming
2012-01-01
This study constructed a questionnaire, named "Lifestyle Change in Regard to Problematic Internet Use (LC-PIU)," for helping school psychologists detect early indications of PIU-related lifestyle changes in university populations. Our focus is on all university students who use the Internet, not users who already show dependent symptoms. The…
NATIONAL INSTITUTES OF HEALTH Diet History Questionnaire Today's date: MONTH DAY YEAR |___|___| 0 0 1 1 2 2 3 3 4 5 6 7 8 01 Jan 02 Feb 03 Mar 04 Apr 05 May 06 Jun 07 Jul 08 Aug 09 Sep 10 Oct 11 Nov 12
Narcotics Center Questionnaire, 1968.
ERIC Educational Resources Information Center
Marks, John B.; And Others
This questionnaire assesses drug knowledge, drug use practices, and attitudes toward drugs in junior high school, senior high school, and college students. The 105 items (multiple choice, yes/no, or completion) are concerned with personal and demographic data, "book" knowledge of drugs, "street" knowledge of drugs (drug argot and the like),…
Questionnaire typography and production.
Gray, M
1975-06-01
This article describes the typographic principles and practice which provide the basis of good design and print, the relevant printing processes which can be used, and the graphic designer's function in questionnaire production. As they impose constraints on design decisions to be discussed later in the text, the various methods of printing and production are discussed first. PMID:15677172
Iles-Smith, Jake; Lambert, Neill; Nazir, Ahsan
2015-01-01
We explore excitonic energy transfer dynamics in a molecular dimer system coupled to both structured and unstructured oscillator environments. By extending the reaction coordinate master equation technique developed in [J. Iles-Smith, N. Lambert, and A. Nazir, Phys. Rev. A 90, 032114 (2014)], we go beyond the commonly used Born-Markov approximations to incorporate system-environment correlations and the resultant non-Markovian dynamical effects. We obtain energy transfer dynamics for both underdamped and overdamped oscillator environments that are in perfect agreement with the numerical hierarchical equations of motion over a wide range of parameters. Furthermore, we show that the Zusman equations, which may be obtained in a semiclassical limit of the reaction coordinate model, are often incapable of describing the correct dynamical behaviour. This demonstrates the necessity of properly accounting for quantum correlations generated between the system and its environment when the Born-Markov approximations no ...
ERIC Educational Resources Information Center
Novotna, Jarmila; Hoch, Maureen
2008-01-01
Many students have difficulties with basic algebraic concepts at high school and at university. In this paper two levels of algebraic structure sense are defined: for high school algebra and for university algebra. We suggest that high school algebra structure sense components are sub-components of some university algebra structure sense…
NASA Astrophysics Data System (ADS)
Myeong, Jeon-Ok; Crawley, Frank E.
The theory of reasoned action (Ajzen & Fishbein, 1980; Fishbein & Ajzen, 1975) was used to predict and understand Korean high school students' track choice for college entrance. First-year high school students (N = 665) from four representative regions of Korea participated in the study. The survey instruments were questionnaires developed according to the guidelines of the TRA. The target behavior of interest in this study was Korean students' choice of the science track when they completed the track application forms during the first year of high school. Predictors included TRA model and external variables. Multiple regression and the structural equation modeling with LISREL (Jöreskog & Sörbom, 1986) were used to analyze the data. The TRA was found to be applicable for understanding and predicting track choice, with minor modifications. Subjective norm was found to exert a direct influence on personal beliefs and the target behavior.
Toda, Hiroyuki; Inoue, Takeshi; Tsunoda, Tomoya; Nakai, Yukiei; Tanichi, Masaaki; Tanaka, Teppei; Hashimoto, Naoki; Nakato, Yasuya; Nakagawa, Shin; Kitaichi, Yuji; Mitsui, Nobuyuki; Boku, Shuken; Tanabe, Hajime; Nibuya, Masashi; Yoshino, Aihide; Kusumi, Ichiro
2015-01-01
Background Previous studies have shown the interaction between heredity and childhood stress or life events on the pathogenesis of a major depressive disorder (MDD). In this study, we tested our hypothesis that childhood abuse, affective temperaments, and adult stressful life events interact and influence the diagnosis of MDD. Patients and methods A total of 170 healthy controls and 98 MDD patients were studied using the following self-administered questionnaire surveys: the Patient Health Questionnaire-9 (PHQ-9), the Life Experiences Survey, the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire, and the Child Abuse and Trauma Scale (CATS). The data were analyzed with univariate analysis, multivariable analysis, and structural equation modeling. Results The neglect scores of the CATS indirectly predicted the diagnosis of MDD through cyclothymic and anxious temperament scores of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire in the structural equation modeling. Two temperaments – cyclothymic and anxious – directly predicted the diagnosis of MDD. The validity of this result was supported by the results of the stepwise multivariate logistic regression analysis as follows: three factors – neglect, cyclothymic, and anxious temperaments – were significant predictors of MDD. Neglect and the total CATS scores were also predictors of remission vs treatment-resistance in MDD patients independently of depressive symptoms. Limitations The sample size was small for the comparison between the remission and treatment-resistant groups in MDD patients in multivariable analysis. Conclusion This study suggests that childhood abuse, especially neglect, indirectly predicted the diagnosis of MDD through increased affective temperaments. The important role as a mediator of affective temperaments in the effect of childhood abuse on MDD was suggested. PMID:26316754
On the minimal set of conservation laws and the Hamiltonian structure of the Whitham equations
A. Ya. Maltsev
2015-03-03
We consider the questions connected with the Hamiltonian properties of the Whitham equations in case of several spatial dimensions. An essential point of our approach here is a connection of the Hamiltonian structure of the Whitham system with the finite-dimensional Poisson bracket defined on the space of periodic or quasi-periodic solutions. From our point of view, this approach gives a possibility to construct the Hamiltonian structure of the Whitham equations under minimal requirements on the properties of the initial system. The Poisson bracket for the Whitham system can be considered here as a deformation of the finite-dimensional bracket with the aid of the Dubrovin - Novikov procedure of bracket averaging. At the end, we consider the examples where the constructions of the paper play an essential role for the construction of the Poisson bracket for the Whitham system.
Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation
NASA Technical Reports Server (NTRS)
Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)
2002-01-01
This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.
Numerical solution of quadratic matrix equations for free vibration analysis of structures
NASA Technical Reports Server (NTRS)
Gupta, K. K.
1975-01-01
This paper is concerned with the efficient and accurate solution of the eigenvalue problem represented by quadratic matrix equations. Such matrix forms are obtained in connection with the free vibration analysis of structures, discretized by finite 'dynamic' elements, resulting in frequency-dependent stiffness and inertia matrices. The paper presents a new numerical solution procedure of the quadratic matrix equations, based on a combined Sturm sequence and inverse iteration technique enabling economical and accurate determination of a few required eigenvalues and associated vectors. An alternative procedure based on a simultaneous iteration procedure is also described when only the first few modes are the usual requirement. The employment of finite dynamic elements in conjunction with the presently developed eigenvalue routines results in a most significant economy in the dynamic analysis of structures.
Quantum structure emerging from the transformation design of the Dirac equation
Lin, De-Hone
2014-06-15
It is shown that a quantum structure can be created by a set of chosen constraint conditions that emerge from the transformation design of the Dirac equation in general relativity. As an explanation, the constraints that cause novel bound states with the quantization rule of a 2D Coulomb system are presented. The discussion in this paper provides a systematic way to look for constraints that generate a required quantization rule. -- Highlights: •We perform the transformation design of space and time for spin-1/2 matter waves. •A quantum rule could naturally emerge as constraints imposed on the Dirac equation itself. •New fermion states share the quantum spectrum of a 2D Coulomb system. •Transformation design uncovers a new exact solvable model. •A quantum spectrum can be created by a geometric structure.
ERIC Educational Resources Information Center
Armey, Michael F.; Fresco, David M.; Moore, Michael T.; Mennin, Douglas S.; Turk, Cynthia L.; Heimberg, Richard G.; Kecmanovic, Jelena; Alloy, Lauren B.
2009-01-01
Depressive rumination, as assessed by Nolen-Hoeksema's Response Styles Questionnaire (RSQ), predicts the onset, chronicity, and duration of depressed mood. However, some RSQ items contain depressive content and result in a heterogeneous factor structure. After the a priori elimination of items potentially confounded with depressed item content,…
Hamiltonian structures of nonlinear evolution equations connected with a polynomial pencil
Gadzhiev, I.T.; Gerdzhikov, V.S.; Ivanov, M.I.
1986-09-01
For a generalized Zakharov-Shabat system in which the matrix potential is a polynomial in the spectral parameter a generating operator is constructed which makes it possible to compactly write out the nonlinear evolution equations (NEE) connected with the system. The eigenfunctions of the generating operator - the ''squares'' of solutions of the original system - are found. The Hamiltonian property of the NEE and the existence of a hierachy of Hamiltonian structures are established.
Jacobi equations and Comparison Theorems for corank 1 sub-Riemannian structures with symmetries
NASA Astrophysics Data System (ADS)
Li, Chengbo; Zelenko, Igor
2011-04-01
The Jacobi curve of an extremal of optimal control problem is a curve in a Lagrangian Grassmannian defined up to a symplectic transformation and containing all information about the solutions of the Jacobi equations along this extremal. In our previous works we constructed the canonical bundle of moving frames and the complete system of symplectic invariants, called curvature maps, for parametrized curves in Lagrange Grassmannians satisfying very general assumptions. The structural equation for a canonical moving frame of the Jacobi curve of an extremal can be interpreted as the normal form for the Jacobi equation along this extremal and the curvature maps can be seen as the "coefficients" of this normal form. In the case of a Riemannian metric there is only one curvature map and it is naturally related to the Riemannian curvature tensor. In the present paper we study the curvature maps for a sub-Riemannian structure on a corank 1 distribution having an additional transversal infinitesimal symmetry. After the factorization by the integral foliation of this symmetry, such sub-Riemannian structure can be reduced to a Riemannian manifold equipped with a closed 2-form (a magnetic field). We obtain explicit expressions for the curvature maps of the original sub-Riemannian structure in terms of the curvature tensor of this Riemannian manifold and the magnetic field. We also estimate the number of conjugate points along the sub-Riemannian extremals in terms of the bounds for the curvature tensor of this Riemannian manifold and the magnetic field in the case of a uniform magnetic field. The language developed for the calculation of the curvature maps can be applied to more general sub-Riemannian structures with symmetries, including sub-Riemmannian structures appearing naturally in Yang-Mills fields.
He, Tung-Hsien; Chang, Shan-Mao; Chen, Shu-Hui Eileen; Gou, Wen Johnny
2012-02-01
This study applied structural equation modeling (SEM) techniques to define the relations among trichotomous goals (mastery goals, performance-approach goals, and performance-avoidance goals), self-efficacy, use of metacognitive self-regulation strategies, positive belief in seeking help, and help-avoidance behavior. Elementary school students (N = 105), who were learning English as a foreign language, were surveyed using five self-report scales. The structural equation model showed that self-efficacy led to the adoption of mastery goals but discouraged the adoption of performance-approach goals and performance-avoidance goals. Furthermore, mastery goals increased the use of metacognitive self-regulation strategies, whereas performance-approach goals and performance-avoidance goals reduced their use. Mastery goals encouraged positive belief in help-seeking, but performance-avoidance goals decreased such belief. Finally, performance-avoidance goals directly led to help-avoidance behavior, whereas positive belief assumed a critical role in reducing help-avoidance. The established structural equation model illuminated the potential causal relations among these variables for the young learners in this study. PMID:22582685
Cosmological structure formation under MOND: a new numerical solver for Poisson's equation
NASA Astrophysics Data System (ADS)
Llinares, Claudio; Knebe, Alexander; Zhao, Hongsheng
2008-12-01
We present a novel solver for an analogue to Poisson's equation in the framework of modified Newtonian dynamics (MOND). This equation is highly non-linear and hence standard codes based upon tree structures and/or fast Fourier transforms in general are not applicable; one needs to defer to multigrid relaxation techniques. After a detailed description of the necessary modifications to the cosmological N-body code AMIGA (formerly known as MLAPM) we utilize the new code to revisit the issue of cosmic structure formation under MOND. We find that the proper (numerical) integration of a MONDian Poisson's equation has some noticeable effects on the final results when compared against simulations of the same kind but based upon rather ad hoc assumptions about the properties of the MONDian force field. Namely, we find that the large-scale structure evolution is faster in our revised MOND model leading to an even stronger clustering of galaxies, especially when compared to the standard ? cold dark matter paradigm.
Chiorri, Carlo; Marsh, Herbert W; Ubbiali, Alessandro; Donati, Deborah
2016-01-01
Confirmatory factor analyses (CFAs) typically fail to support the a priori 5-factor structure of Big Five self-report instruments, due in part to the overly restrictive CFA assumptions. We show that exploratory structural equation modeling (ESEM), an integration of CFA and exploratory factor analysis, overcomes these problems in relation to responses to the 44-item Big Five Inventory (BFI) administered to a large Italian community sample. ESEM fitted the data better and resulted in less correlated factors than CFA, although ESEM and CFA factor scores correlated at near unity with observed raw scores. Tests of gender invariance with a 13-model taxonomy of full measurement invariance showed that the factor structure of the BFI is gender-invariant and that women score higher on Neuroticism, Agreeableness, Extraversion, and Conscientiousness. Through ESEM one could address substantively important issues about BFI psychometric properties that could not be appropriately addressed through traditional approaches. PMID:25932664
Solution of linear systems of equations with a structural analysis code on the NAS CRAY-2
Poole, E.L.; Overman, A.L.
1988-12-01
Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.
Numerical solution of Q2 evolution equations for polarized structure functions
NASA Astrophysics Data System (ADS)
Hirai, M.; Kumano, S.; Miyama, M.
1998-01-01
We investigate numerical solution of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) Q2 evolution equations for longitudinally polarized structure functions. Flavor nonsinglet and singlet equations with next-to-leading-order ?s corrections are studied. A brute-force method is employed. Dividing the variables x and Q2 into small steps, we simply solve the integrodifferential equations. Numerical results indicate that accuracy is better than 1% in the region 10 -5 < x < 0.8 if more than two hundred Q2 steps and more than one thousand x steps are taken. Our evolution results are compared with polarized experimental data of the spin asymmetry A1 by the SLAC-E130, SLAC-E143, EMC, and SMC collaborations. The comparison indicates that we cannot assume A1 is independent of Q2. We provide a FORTRAN program for the Q2 evolution and devolution of polarized nonsinglet-quark, singlet-quark, ?q i+? overlineqi, and gluon distributions (and corresponding structure functions).
Using Presence Questionnaires in Reality Using Presence Questionnaires in Reality
Slater, Mel
compared to immersive virtual. #12;Using Presence Questionnaires in Reality 2 1. Introduction The concept1 Using Presence Questionnaires in Reality Using Presence Questionnaires in Reality Martin Usoh different presence question- naires can distinguish between real and virtual experiences. One group of 10
A structurally damped plate equation with Dirichlet-Neumann boundary conditions
NASA Astrophysics Data System (ADS)
Denk, Robert; Schnaubelt, Roland
2015-08-01
We investigate sectoriality and maximal regularity in Lp-Lq-Sobolev spaces for the structurally damped plate equation with Dirichlet-Neumann (clamped) boundary conditions. We obtain unique solutions with optimal regularity for the inhomogeneous problem in the whole space, in the half-space, and in bounded domains of class C4. It turns out that the first-order system related to the scalar equation on Rn is sectorial only after a shift in the operator. On the half-space one has to include zero boundary conditions in the underlying function space in order to obtain sectoriality of the shifted operator and maximal regularity for the case of homogeneous boundary conditions. We further show that the semigroup solving the problem on bounded domains is exponentially stable.
NASA Astrophysics Data System (ADS)
Gonczarek, Ryszard; Krzyzosiak, Mateusz; Gonczarek, Adam; Jacak, Lucjan
2015-06-01
In this paper, we discuss the mathematical structure of the s-wave superconducting gap and other quantitative characteristics of superconducting systems. In particular, we evaluate and discuss integrals inherent in fundamental equations describing superconducting systems. The results presented here extend the approach formulated by Abrikosov and Maki, which was restricted to the first-order expansion. A few infinite families of integrals are derived and allow us to express the fundamental equations by means of analytic formulas. They can be then exploited in order to find some quantitative characteristics of superconducting systems by the method of successive approximations. We show that the results can be applied to some modern formalisms in order to study high-Tc superconductors and other superconducting materials of the new generation.
Rusli, Bin Nordin; Edimansyah, Bin Abdin; Naing, Lin
2008-01-01
Background The relationships between working conditions [job demand, job control and social support]; stress, anxiety, and depression; and perceived quality of life factors [physical health, psychological wellbeing, social relationships and environmental conditions] were assessed using a sample of 698 male automotive assembly workers in Malaysia. Methods The validated Malay version of the Job Content Questionnaire (JCQ), Depression Anxiety Stress Scales (DASS) and the World Health Organization Quality of Life-Brief (WHOQOL-BREF) were used. A structural equation modelling (SEM) analysis was applied to test the structural relationships of the model using AMOS version 6.0, with the maximum likelihood ratio as the method of estimation. Results The results of the SEM supported the hypothesized structural model (?2 = 22.801, df = 19, p = 0.246). The final model shows that social support (JCQ) was directly related to all 4 factors of the WHOQOL-BREF and inversely related to depression and stress (DASS). Job demand (JCQ) was directly related to stress (DASS) and inversely related to the environmental conditions (WHOQOL-BREF). Job control (JCQ) was directly related to social relationships (WHOQOL-BREF). Stress (DASS) was directly related to anxiety and depression (DASS) and inversely related to physical health, environment conditions and social relationships (WHOQOL-BREF). Anxiety (DASS) was directly related to depression (DASS) and inversely related to physical health (WHOQOL-BREF). Depression (DASS) was inversely related to the psychological wellbeing (WHOQOL-BREF). Finally, stress, anxiety and depression (DASS) mediate the relationships between job demand and social support (JCQ) to the 4 factors of WHOQOL-BREF. Conclusion These findings suggest that higher social support increases the self-reported quality of life of these workers. Higher job control increases the social relationships, whilst higher job demand increases the self-perceived stress and decreases the self-perceived quality of life related to environmental factors. The mediating role of depression, anxiety and stress on the relationship between working conditions and perceived quality of life in automotive workers should be taken into account in managing stress amongst these workers. PMID:18254966
OpenMx: An Open Source Extended Structural Equation Modeling Framework
Boker, Steven; Neale, Michael; Maes, Hermine; Wilde, Michael; Spiegel, Michael; Brick, Timothy; Spies, Jeffrey; Estabrook, Ryne; Kenny, Sarah; Bates, Timothy; Mehta, Paras; Fox, John
2012-01-01
OpenMx is free, full–featured, open source, structural equation modeling (SEM) software. OpenMx runs within the R statistical programming environment on Windows, Mac OS–X, and Linux computers. The rationale for developing OpenMx is discussed along with the philosophy behind the user interface. The OpenMx data structures are introduced — these novel structures define the user interface framework and provide new opportunities for model specification. Two short example scripts for the specification and fitting of a confirmatory factor model are next presented. We end with an abbreviated list of modeling applications available in OpenMx 1.0 and a discussion of directions for future development. PMID:23258944
Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven
2012-01-01
Truant youth represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining co-morbid problem behaviors. The present study addresses the need to examine the interrelationships of multiple domains of psychosocial functioning, including substance involvement, mental health, and delinquency, among truant youth. Exploratory structural equation modeling on baseline data collected on 219 truant youths identified two major factors reflecting psychosocial functioning, and found the factor structure was similar across major sociodemographic subgroups. Further analyses supported the validity of the factor structure. The research and service delivery implications of the findings are discussed. PMID:23243383
NASA Astrophysics Data System (ADS)
Nosov, Victor V.; Lukin, Vladimir P.; Nosov, Evgeny V.; Torgaev, Andrey V.
2014-11-01
Coherent structures (topological solitons) indoors had been simulated by numerical solving of hydrodynamics equations. "Indoors" means inside the closed volume without the external direct wind influence and without the exchange of internal and external medium through the borders. Results of six boundary value problems are demonstrated: spectrograph pavilion and telescope dome of large astronomical telescopes (LSVT and BTA), cubic room, flat square cuvette, square section tube, parietal turbulence (thermals). The solitary large vortices (coherent structures, topological solitons) are observed indoors. The scenes of air motion as a result of simulation of coherent structures with identical boundary conditions are the practically same as the scenes, independently previously registered at experiments by us (indoors LSVT and BTA).
ATBC Study - Questionnaires and Forms
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Guides & Reports for Questionnaire Design
Applied Research Program (ARP) staff use a variety of methods to develop and test questionnaires, including established Questionnaire Design Principles, empirical methods such as Cognitive Testing and psychometric methods such as Item Response Theory Modeling.
Diet History Questionnaire: International Applications
ARP staff adapted the Diet History Questionnaire (DHQ) for use by Canadian populations in collaboration with the Alberta Cancer Board. This questionnaire takes into account the different food fortification polices of the U.S. and Canada.
Diet History Questionnaire: Suggested Citations
Use of the Diet History Questionnaire and Diet*Calc Analysis Software for publication purposes should contain a citation which includes version information for the software, questionnaire, and nutrient database.
Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack
2014-01-01
The present study assessed the impact of sample size on the power and fit of structural equation modeling applied to functional brain connectivity hypotheses. The data consisted of time-constrained minimum norm estimates of regional brain activity during performance of a reading task obtained with magnetoencephalography. Power analysis was first conducted for an autoregressive model with 5 latent variables (brain regions), each defined by 3 indicators (successive activity time bins). A series of simulations were then run by generating data from an existing pool of 51 typical readers (aged 7.5-12.5 years). Sample sizes ranged between 20 and 1,000 participants and for each sample size 1,000 replications were run. Results were evaluated using chi-square Type I errors, model convergence, mean RMSEA (root mean square error of approximation) values, confidence intervals of the RMSEA, structural path stability, and D-Fit index values. Results suggested that 70 to 80 participants were adequate to model relationships reflecting close to not so close fit as per MacCallum et al.'s recommendations. Sample sizes of 50 participants were associated with satisfactory fit. It is concluded that structural equation modeling is a viable methodology to model complex regional interdependencies in brain activation in pediatric populations. PMID:25435589
Structural equation modeling of sleep apnea, inflammation, and metabolic dysfunction in children.
Waters, Karen A; Mast, Benjamin T; Vella, Silvano; de la Eva, Roland; O'Brien, Louise M; Bailey, Sherryn; Tam, Charmaine S; Wong, Melanie; Baur, Louise A
2007-12-01
Obstructive sleep apnea (OSA), often concomitant with obesity, increases the risk for the metabolic syndrome. One mechanism that may participate in this association is upregulation of inflammatory pathways. We used structural equation modeling to assess the interrelations between childhood obesity, OSA, inflammation, and metabolic dysfunction. One hundred and eighty-four children (127 boys, mean age: 8.5 +/- 4.1 years) had height and weight measured, underwent overnight polysomnography and had fasting blood taken. The blood was analyzed for insulin, glucose, lipids, leptin, and cytokines [interferon (IFN)-gamma, granulocyte macrophage-colony stimulating factor, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-alpha]. Structural equation modeling (SEM) was used to evaluate associations between the outcomes of interest including hypoxia, arousal (related to respiratory and spontaneous), obesity, metabolic dysfunction, and inflammatory markers. Two cytokine factors and one metabolic factor were derived for the SEM. These factors provided good fit in the structural equation model (chi(2)/df = 2.855; comparative fit index = 0.90, root mean squared error of approximation = 0.10) and all factor loadings were significantly different from zero (P < or = 0.01). Overall, our results indicate that while obesity (as measured by body mass index z-score) has a major influence on the metabolic dysfunction associated with OSA, arousal indices, and cytokine markers may also influence this association. Our results support the hypothesis that OSA is a contributor to the mechanisms that link sleep, systemic inflammation and insulin resistance, and show that the interrelations may begin in childhood. PMID:18036084
Hsu, Hsien-Yuan
2011-02-22
Two Monte Carlo studies were conducted to investigate the sensitivity of fit indices in detecting model misspecification in multilevel structural equation models (MSEM) with normally distributed or dichotomous outcome variables separately under...
Kyougoku, Makoto
2015-01-01
Purpose. The purpose of this study is to demonstrate the hypothetical model based on structural relationship with the occupational dysfunction on psychological problems (stress response, burnout syndrome, and depression) in healthcare workers. Method. Three cross sectional studies were conducted to assess the following relations: (1) occupational dysfunction on stress response (n = 468), (2) occupational dysfunction on burnout syndrome (n = 1,142), and (3) occupational dysfunction on depression (n = 687). Personal characteristics were collected through a questionnaire (such as age, gender, and job category, opportunities for refreshment, time spent on leisure activities, and work relationships) as well as the Classification and Assessment of Occupational Dysfunction (CAOD). Furthermore, study 1 included the Stress Response Scale-18 (SRS-18), study 2 used the Japanese Burnout Scale (JBS), and study 3 employed the Center for Epidemiological Studies Depression Scale (CES-D). The Kolmogorov–Smirnov test, confirmatory factor analysis (CFA), exploratory factor analysis (EFA), and path analysis of structural equation modeling (SEM) analysis were used in all of the studies. EFA and CFA were used to measure structural validity of four assessments; CAOD, SRS-18, JBS, and CES-D. For examination of a potential covariate, we assessed the correlation of the total and factor score of CAOD and personal factors in all studies. Moreover, direct and indirect effects of occupational dysfunction on stress response (Study 1), burnout syndrome (Study 2), and depression (Study 3) were also analyzed. Results. In study 1, CAOD had 16 items and 4 factors. In Study 2 and 3, CAOD had 16 items and 5 factors. SRS-18 had 18 items and 3 factors, JBS had 17 items and 3 factors, and CES-D had 20 items and 4 factors. All studies found that there were significant correlations between the CAOD total score and the personal factor that included opportunities for refreshment, time spent on leisure activities, and work relationships (p < 0.01). The hypothesis model results suggest that the classification of occupational dysfunction had good fit on the stress response (RMSEA = 0.061, CFI = 0.947, and TLI = 0.943), burnout syndrome (RMSEA = 0.076, CFI = 0.919, and TLI = 0.913), and depression (RMSEA = 0.060, CFI = 0.922, TLI = 0.917). Moreover, the detected covariates include opportunities for refreshment, time spent on leisure activities, and work relationships on occupational dysfunction. Conclusion. Our findings indicate that psychological problems are associated with occupational dysfunction in healthcare workers. Reduction of occupational dysfunction might be a strategy of better preventive occupational therapies for healthcare workers with psychological problems. However, longitudinal studies will be needed to determine a causal relationship. PMID:26618078
NASA Astrophysics Data System (ADS)
Hussain, Nur Farahin Mee; Zahid, Zalina
2014-12-01
Nowadays, in the job market demand, graduates are expected not only to have higher performance in academic but they must also be excellent in soft skill. Problem-Based Learning (PBL) has a number of distinct advantages as a learning method as it can deliver graduates that will be highly prized by industry. This study attempts to determine the satisfaction level of engineering students on the PBL Approach and to evaluate their determinant factors. The Structural Equation Modeling (SEM) was used to investigate how the factors of Good Teaching Scale, Clear Goals, Student Assessment and Levels of Workload affected the student satisfaction towards PBL approach.
Shadwick, B.A.; Buell, W.F.; Shadwick, B.A.
1997-12-01
The quantum Liouville equation for an n-level atomic system driven by external fields has a nontrivial kinematic structure; the quantities tr {rho}{sup j}, j=1,2,{hor_ellipsis},n remain constant in time, independent of the Hamiltonian. These invariants are physically significant; the qualitative character of the solution depends on their existence. A generic numerical method will not, in general, preserve these invariants. We present a numerical technique which evolves the density matrix {ital via} unitary transformations thus {ital exactly} preserving these invariants to {ital all orders} in the time step. {copyright} {ital 1997} {ital The American Physical Society}
The Use of Structural Equation Modeling in Stuttering Research: Concepts and Directions
Levine, Stephen Z.; Petrides, K. V.; Davis, Stephen; Jackson, Chris J.; Howell, Peter
2007-01-01
This article provides a brief introduction to the history and applications of the class of data analytic techniques collectively known as Structural Equation Modeling (SEM). Using an example based on psychological factors thought to affect the likelihood of stuttering, we discuss the issues of specification, identification, and model fit and modification in SEM. We also address points relating to model specification strategies, item parceling, advanced modeling, and suggestions for reporting SEM analyses. It is noted that SEM techniques can contribute to the elucidation of the developmental pathways that lead to stuttering. PMID:18677423
Integrable structure of conformal field theory; 2, q-operator and DDV equation
Bazhanov, V V; Zamolodchikov, A B
1996-01-01
This paper is a direct continuation of \\BLZ\\ where we begun the study of the integrable structures in Conformal Field Theory. We show here how to construct the operators {\\bf Q}_{\\pm}(\\lambda) which act in highest weight Virasoro module and commute for different values of the parameter \\lambda. These operators appear to be the CFT analogs of the Q - matrix of Baxter\\ \\Baxn , in particular they satisfy famous Baxter's {\\bf T}-{\\bf Q} equation. We also show that under natural assumptions about analytic properties of the operators {\\bf Q}(\\lambda) as the functions of \\lambda the Baxter's relation allows one to derive the nonlinear integral equations of Destri-de Vega (DDV) \\dVega\\ for the eigenvalues of the {\\bf Q}-operators. We then use the DDV equation to obtain the asymptotic expansions of the {\\bf Q} - operators at large \\lambda; it is remarkable that unlike the expansions of the {\\bf T} operators of \\ \\BLZ, the asymptotic series for {\\bf Q}(\\lambda) contains the "dual" nonlocal Integrals of Motion along wit...
Integrable Structure of Conformal Field Theory II. Q-operator and DDV equation
V. Bazhanov; S. Lukyanov; A. Zamolodchikov
1996-04-17
This paper is a direct continuation of\\ \\BLZ\\ where we begun the study of the integrable structures in Conformal Field Theory. We show here how to construct the operators ${\\bf Q}_{\\pm}(\\lambda)$ which act in highest weight Virasoro module and commute for different values of the parameter $\\lambda$. These operators appear to be the CFT analogs of the $Q$ - matrix of Baxter\\ \\Baxn, in particular they satisfy famous Baxter's ${\\bf T}-{\\bf Q}$ equation. We also show that under natural assumptions about analytic properties of the operators ${\\bf Q}(\\lambda)$ as the functions of $\\lambda$ the Baxter's relation allows one to derive the nonlinear integral equations of Destri-de Vega (DDV)\\ \\dVega\\ for the eigenvalues of the ${\\bf Q}$-operators. We then use the DDV equation to obtain the asymptotic expansions of the ${\\bf Q}$ - operators at large $\\lambda$; it is remarkable that unlike the expansions of the ${\\bf T}$ operators of \\ \\BLZ, the asymptotic series for ${\\bf Q}(\\lambda)$ contains the ``dual'' nonlocal Integrals of Motion along with the local ones. We also discuss an intriguing relation between the vacuum eigenvalues of the ${\\bf Q}$ - operators and the stationary transport properties in boundary sine-Gordon model. On this basis we propose a number of new exact results about finite voltage charge transport through the point contact in quantum Hall system.
Integrable Structure of Conformal Field Theory II. Q-operator and DDV equation
NASA Astrophysics Data System (ADS)
Bazhanov, Vladimir V.; Lukyanov, Sergei L.; Zamolodchikov, Alexander B.
This paper is a direct continuation of [1] where we began the study of the integrable structures in Conformal Field Theory. We show here how to construct the operators Q+/-(? ) which act in the highest weight Virasoro module and commute for different values of the parameter ?. These operators appear to be the CFT analogs of the Q - matrix of Baxter [2], in particular they satisfy Baxter's famous T- Q equation. We also show that under natural assumptions about analytic properties of the operators as the functions of ? the Baxter's relation allows one to derive the nonlinear integral equations of Destri-de Vega (DDV) [3] for the eigenvalues of the Q-operators. We then use the DDV equation to obtain the asymptotic expansions of the Q - operators at large ? it is remarkable that unlike the expansions of the T operators of [1], the asymptotic series for Q(?) contains the ``dual'' nonlocal Integrals of Motion along with the local ones. We also discuss an intriguing relation between the vacuum eigenvalues of the Q - operators and the stationary transport properties in the boundary sine-Gordon model. On this basis we propose a number of new exact results about finite voltage charge transport through the point contact in the quantum Hall system.
Job and Professional Leaving Among Newly Licensed RNs: A Structural Equation Model.
Unruh, Lynn; Zhang, Ning Jackie; Chisolm, Latarsha
2016-01-01
With more than 50% of the nursing workforce close to retirement, it is especially important to keep younger nurses in nursing jobs and careers. This study empirically tests a structural equation model of registered nurse (RN) intent to leave the job and profession using data from a survey of newly licensed RNs (NLRNs). Job demands, difficulties and control, intent to leave the job, and intent to leave the profession were latent variables. A number of direct, indirect, and mediating relationships were modeled. Measurement models for all latent variables and the structural model had good fit. The final model showed a path from job demands, difficulties, and control to job satisfaction to intent to leave the job to intent to leave the profession. The results suggest that the process of an NLRN intending to leave the job and profession involves a number of mediators between the work environment and this intent. PMID:25433000
Duncan, T E; Stoolmiller, M
1993-03-01
Recent advances in structural modeling techniques allow for the testing of complex models representing social and behavioral processes. However, most reported applications in sport and physical activity have been limited to simple models involving variables measured at a single point in time. Therefore, the purpose of this article is to demonstrate the use of both cross-sectional and longitudinal latent variable modeling techniques by examining the relationships among efficacy cognitions, social support, and the exercise behaviors of sedentary adults. Results revealed a good fit for the re-specified model, suggesting the existence of a lagged feedback mechanism in which exercise behaviors influenced residual change in social support. In turn, efficacy cognitions appeared to serve a mediational function in the synchronous relationship between social support and exercise behavior. Findings are discussed in terms of the utility of structural equation modeling techniques for understanding the complex social and cognitive processes involved in exercise behavior. PMID:8451525
NASA Astrophysics Data System (ADS)
Kim, Min-Geun; Jang, Hong-Lae; Cho, Seonho
2013-05-01
An efficient adjoint design sensitivity analysis method is developed for reduced atomic systems. A reduced atomic system and the adjoint system are constructed in a locally confined region, utilizing generalized Langevin equation (GLE) for periodic lattice structures. Due to the translational symmetry of lattice structures, the size of time history kernel function that accounts for the boundary effects of the reduced atomic systems could be reduced to a single atom's degrees of freedom. For the problems of highly nonlinear design variables, the finite difference method is impractical for its inefficiency and inaccuracy. However, the adjoint method is very efficient regardless of the number of design variables since one additional time integration is required for the adjoint GLE. Through numerical examples, the derived adjoint sensitivity turns out to be accurate and efficient through the comparison with finite difference sensitivity.
Killing-Yano equations with torsion, worldline actions and G-structures
G. Papadopoulos
2011-11-29
We determine the geometry of the target spaces of supersymmetric non-relativistic particles with torsion and magnetic couplings, and with symmetries generated by the fundamental forms of G-structures for $G= U(n), SU(n), Sp(n), Sp(n)\\cdot Sp(1), G_2$ and $Spin(7)$. We find that the Killing-Yano equation, which arises as a condition for the invariance of the worldline action, does not always determine the torsion coupling uniquely in terms of the metric and fundamental forms. We show that there are several connections with skew-symmetric torsion for $G=U(n), SU(n)$ and $G_2$ that solve the invariance conditions. We describe all these compatible connections for each of the $G$-structures and explain the geometric nature of the couplings.
NASA Astrophysics Data System (ADS)
Liu, Zhihua; Magal, Pierre; Ruan, Shigui
2014-08-01
Normal form theory is very important and useful in simplifying the forms of equations restricted on the center manifolds in studying nonlinear dynamical problems. In this paper, using the center manifold theorem associated with the integrated semigroup theory, we develop a normal form theory for semilinear Cauchy problems in which the linear operator is not densely defined and is not a Hille-Yosida operator and present procedures to compute the Taylor expansion and normal form of the reduced system restricted on the center manifold. We then apply the main results and computation procedures to determine the direction of the Hopf bifurcation and stability of the bifurcating periodic solutions in a structured evolutionary epidemiological model of influenza A drift and an age structured population model.
Wing Kai Wong
1996-01-05
We use the BLM procedure to eliminate the renormalization scale ambiguity in the evolution equation for the non-singlet deep-inelastic structure function $F_2^{\\text NS}(x,Q).$ The scale of the QCD coupling in the $\\overline{\\text{MS}}$ scheme has the form $Q^*(x) = Q (1-x)^{1/2} / x~f(x) $, where $x$ is the Bjorken variable and $f(x)$ is a smoothly varying function bounded between 0.30 to 0.45. Equivalently, the evolution of the $n$th moment of the structure function should contain an effective $\\Lambda_{\\text{QCD}}$ pattern, with $\\Lambda_n \\sim n^{1/2}$. This variation of $\\Lambda_n$ agrees with experimental data.
Kim, Min-Geun; Jang, Hong-Lae; Cho, Seonho
2013-05-01
An efficient adjoint design sensitivity analysis method is developed for reduced atomic systems. A reduced atomic system and the adjoint system are constructed in a locally confined region, utilizing generalized Langevin equation (GLE) for periodic lattice structures. Due to the translational symmetry of lattice structures, the size of time history kernel function that accounts for the boundary effects of the reduced atomic systems could be reduced to a single atom’s degrees of freedom. For the problems of highly nonlinear design variables, the finite difference method is impractical for its inefficiency and inaccuracy. However, the adjoint method is very efficient regardless of the number of design variables since one additional time integration is required for the adjoint GLE. Through numerical examples, the derived adjoint sensitivity turns out to be accurate and efficient through the comparison with finite difference sensitivity.
Grace, J.B.; Bollen, K.A.
2008-01-01
Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.
Psychometric Evaluation of the Chinese Virtues Questionnaire
ERIC Educational Resources Information Center
Duan, Wenjie; Ho, Samuel M. Y.; Bai, Yu; Tang, Xiaoqing
2013-01-01
Objectives: The present study examined the psychometric properties of the Chinese Virtues Questionnaire (CVQ). The reliability, factor structure, construct validity, and temporal stability of the inventory were examined. Method: A university student sample ("n" = 878) and a working adult sample ("n" = 153) were recruited.…
Development of high vorticity structures in incompressible 3D Euler equations
NASA Astrophysics Data System (ADS)
Agafontsev, D. S.; Kuznetsov, E. A.; Mailybaev, A. A.
2015-08-01
We perform the systematic numerical study of high vorticity structures that develop in the 3D incompressible Euler equations from generic large-scale initial conditions. We observe that a multitude of high vorticity structures appear in the form of thin vorticity sheets (pancakes). Our analysis reveals the self-similarity of the pancakes evolution, which is governed by two different exponents e-t/T? and et/T? describing compression in the transverse direction and the vorticity growth, respectively, with the universal ratio T?/T? ? 2/3. We relate development of these structures to the gradual formation of the Kolmogorov energy spectrum Ek ? k-5/3, which we observe in a fully inviscid system. With the spectral analysis, we demonstrate that the energy transfer to small scales is performed through the pancake structures, which accumulate in the Kolmogorov interval of scales and evolve according to the scaling law ?max ? ?-2/3 for the local vorticity maximums ?max and the transverse pancake scales ?.
Development of uncertainty-based work injury model using Bayesian structural equation modelling.
Chatterjee, Snehamoy
2014-01-01
This paper proposed a Bayesian method-based structural equation model (SEM) of miners' work injury for an underground coal mine in India. The environmental and behavioural variables for work injury were identified and causal relationships were developed. For Bayesian modelling, prior distributions of SEM parameters are necessary to develop the model. In this paper, two approaches were adopted to obtain prior distribution for factor loading parameters and structural parameters of SEM. In the first approach, the prior distributions were considered as a fixed distribution function with specific parameter values, whereas, in the second approach, prior distributions of the parameters were generated from experts' opinions. The posterior distributions of these parameters were obtained by applying Bayesian rule. The Markov Chain Monte Carlo sampling in the form Gibbs sampling was applied for sampling from the posterior distribution. The results revealed that all coefficients of structural and measurement model parameters are statistically significant in experts' opinion-based priors, whereas, two coefficients are not statistically significant when fixed prior-based distributions are applied. The error statistics reveals that Bayesian structural model provides reasonably good fit of work injury with high coefficient of determination (0.91) and less mean squared error as compared to traditional SEM. PMID:24111548
ERIC Educational Resources Information Center
Rugutt, John Kipngeno
This study used structural equation modeling and multilevel modeling approaches for purposes of simultaneous study of individual and group change patterns on three waves of two longitudinally assessed domains. This study illustrates a few of the dual approaches to the analysis of covariance structures as they relate to the same individual growth…
ERIC Educational Resources Information Center
Caldas, Stephen J.; Cornigans, Linda
2015-01-01
This study used structural equation modeling to conduct a first and second order confirmatory factor analysis (CFA) of a scale developed by McDonald and Moberg (2002) to measure three dimensions of social capital among a diverse group of middle- and upper-middle-class elementary school parents in suburban New York. A structural path model was…
ERIC Educational Resources Information Center
van den Putte, Bas; Hoogstraten, Johan
1997-01-01
Problems found in the application of structural equation modeling to the theory of reasoned action are explored, and an alternative model specification is proposed that improves the fit of the data while leaving intact the structural part of the model being tested. Problems and the proposed alternative are illustrated. (SLD)
Boettger, J.C.; Wills, J.M.
1992-03-01
High precision electronic band structure calculations for BeO have revealed a large volume discontinuity structural phase transition on the 0 K isotherm at about 1 Mbar. Although, this transition has not been observed experimentally, the accuracy of the calculations is such that the existence of this transition is unambiguous. A transition of this magnitude is likely to have a substantial impact on hydrodynamic simulations involving BeO. Here we report the creation of a new SESAME equations of state for BeO which incorporates the effect of the theoretically determined phase transition. This new EOS will be added to the SESAME library as material number 7612.
Physician Enabling Skills Questionnaire
Hudon, Catherine; Lambert, Mireille; Almirall, José
2015-01-01
Abstract Objective To evaluate the reliability and validity of the newly developed Physician Enabling Skills Questionnaire (PESQ) by assessing its internal consistency, test-retest reliability, concurrent validity with patient-centred care, and predictive validity with patient activation and patient enablement. Design Validation study. Setting Saguenay, Que. Participants One hundred patients with at least 1 chronic disease who presented in a waiting room of a regional health centre family medicine unit. Main outcome measures Family physicians’ enabling skills, measured with the PESQ at 2 points in time (ie, while in the waiting room at the family medicine unit and 2 weeks later through a mail survey); patient-centred care, assessed with the Patient Perception of Patient-Centredness instrument; patient activation, assessed with the Patient Activation Measure; and patient enablement, assessed with the Patient Enablement Instrument. Results The internal consistency of the 6 subscales of the PESQ was adequate (Cronbach ? = .69 to .92). The test-retest reliability was very good (r = 0.90; 95% CI 0.84 to 0.93). Concurrent validity with the Patient Perception of Patient-Centredness instrument was good (r = ?0.67; 95% CI ?0.78 to ?0.53; P < .001). The PESQ accounts for 11% of the total variance with the Patient Activation Measure (r2 = 0.11; P = .002) and 19% of the variance with the Patient Enablement Instrument (r2 = 0.19; P < .001). Conclusion The newly developed PESQ presents good psychometric properties, allowing for its use in practice and research.
A structured doubling algorithm for Lur'e Equations Federico Poloni1
Reis, Timo
assumption) is equivalent to solving the algebraic Riccati equation (ARE) [10,12,13] AT X + XA - (XB + C)R-1 to eliminate certain parts of the Lur'e equation, such that a projected algebraic Riccati equation is obtained Lur'e equations of slightly smaller size. After a finite number of steps this leads to an algebraic
Solving the 3D Acoustic Wave-equation on Generalized Structured Meshes: A FDTD Approach
NASA Astrophysics Data System (ADS)
Shragge, J. C.
2014-12-01
The key computational kernel of most advanced 3D seismic imaging and inversion algorithms involves calculating solutions of the 3D acoustic wave equation, most commonly with a finite-difference time-domain (FDTD) methodology. While well suited for regularly sampled rectilinear computational domains, FDTD methods seemingly have limited applicability in scenarios involving irregular 3D domain boundary surfaces and mesh interiors that are best described by non-Cartesian geometry (e.g., surface topography). Using coordinate mapping relationships and differential geometry, a FDTD approach can be developed for generating solutions to the 3D acoustic wave equation that is applicable to generalized 3D coordinate systems and (quadrilateral-faced hexahedral) structured meshes. The developed numerical implementation is similar to established Cartesian approaches, save for a necessary introduction of weighted first- and mixed second-order partial-derivative operators that account for spatially varying geometry. The approach is validated on three different types of computational meshes: (1) an ``internal boundary'' mesh conforming to a dipping water bottom; (2) analytical ``semi-orthogonal cylindrical" coordinates; and (3) analytic semi-orthogonal and numerically specified ``topographic" coordinate meshes. Impulse response tests and numerical analysis demonstrate the viability of the approach for kernel computations for 3D seismic imaging and inversion experiments for non-Cartesian geometry scenarios.
Domenico Gazzillo; Achille Giacometti; Raffaele G. Della Valle; Elisabetta Venuti; Flavio Carsughi
1999-10-15
Integral equation of pure liquids, combined with a new "scaling approximation" based on a corresponding states treatment of pair correlation functions, is used to evaluate approximate structure factors for colloidal fluids constituted of uncharged particles with polydispersity in size and energy parameters. Both hard spheres and Lennard-Jones interactions are considered. For polydisperse hard spheres, the scaling approximation is compared to theories utilized by small angle scattering experimentalists (decoupling approximation, local monodisperse approximation)and to the van der Waals one-fluid theory. The results are tested against predictions from analytical expressions, exact within the Percus-Yevick approximation. For polydisperse Lennard-Jones particles, the scaling approximation combined with a "modified hypernetted chain" integral equation, is tested against molecular dynamics data generated for the present work. Despite ist simplicity, the scaling approximation exhibits a satisfactory performance for both potentials and represents a considerable improvement over the above mentioned theories. Shortcomings of the proposed theory, its applicability to the analysis of experimental scattering data, and its possible extensions to different potentials are finally discussed.
Numerical solutions of Navier-Stokes equations for the structure of a trailing vortex
NASA Technical Reports Server (NTRS)
Jain, A. C.
1977-01-01
The structure and decay of a trailing vortex were analyzed during the numerical solutions of the full Navier-Stokes equations. Unsteady forms of the governing equations were recast in terms of circulation, vorticity, and stream function as dependent variables, and a second upwind finite difference scheme was used to integrate them with prescribed initial and boundary conditions. The boundary conditions at the outer edge and at the outflow section of the trailing vortex were considered. Different models of the flow were postulated, and solutions were obtained describing the development of the flow as integration proceeds in time. A parametric study was undertaken with a view to understanding the various phenomena that may possibly occur in the trailing vortex. Using the Hoffman and Joubert law of circulation at the inflow section, the results of this investigation were compared with experimental data for a Convair 990 wind model and a rectangular wing. With an exponentially decaying law of circulation at the inflow section and an adverse pressure gradient at the outer edge of the trailing vortex, solutions depict vortex bursting through the sudden expansion of the core and/or through the stagnation and consequent reversal of the flow on the axis. It was found that this bursting takes place at lower values of the swirl ratio as the Reynolds number increases.
IQ heritability estimation: analyzing genetically-informative data with structural equation models.
Gallardo Pujol, David; García-Forero, Carlos; Kramp, Uwe; Maydeu-Olivares, Albert; Andrés-Pueyo, Antonio
2007-02-01
When analyzing genetic data, Structural Equations Modeling (SEM) provides a straightforward methodology to decompose phenotypic variance using a model-based approach. Furthermore, several models can be easily implemented, tested, and compared using SEM, allowing the researcher to obtain valuable information about the sources of variability. This methodology is briefly described and applied to re-analyze a Spanish set of IQ data using the biometric ACE model. In summary, we report heritability estimates that are consistent with those of previous studies and support substantial genetic contribution to phenotypic IQ; around 40% of the variance can be attributable to it. With regard to the environmental contribution, shared environment accounts for 50% of the variance, and non-shared environment accounts for the remaining 10%. These results are discussed in the text. PMID:17295998
Analysis of traffic accident size for Korean highway using structural equation models.
Lee, Ju-Yeon; Chung, Jin-Hyuk; Son, Bongsoo
2008-11-01
Accident size can be expressed as the number of involved vehicles, the number of damaged vehicles, the number of deaths and/or the number of injured. Accident size is the one of the important indices to measure the level of safety of transportation facilities. Factors such as road geometric condition, driver characteristic and vehicle type may be related to traffic accident size. However, all these factors interact in complicate ways so that the interrelationships among the variables are not easily identified. A structural equation model is adopted to capture the complex relationships among variables because the model can handle complex relationships among endogenous and exogenous variables simultaneously and furthermore it can include latent variables in the model. In this study, we use 2649 accident data occurred on highways in Korea and estimate relationship among exogenous factors and traffic accident size. The model suggests that road factors, driver factors and environment factors are strongly related to the accident size. PMID:19068300
From patterns to causal understanding: Structural equation modeling (SEM) in soil ecology
Eisenhauer, Nico; Powell, Jeff R; Grace, James B.; Bowker, Matthew A.
2015-01-01
In this perspectives paper we highlight a heretofore underused statistical method in soil ecological research, structural equation modeling (SEM). SEM is commonly used in the general ecological literature to develop causal understanding from observational data, but has been more slowly adopted by soil ecologists. We provide some basic information on the many advantages and possibilities associated with using SEM and provide some examples of how SEM can be used by soil ecologists to shift focus from describing patterns to developing causal understanding and inspiring new types of experimental tests. SEM is a promising tool to aid the growth of soil ecology as a discipline, particularly by supporting research that is increasingly hypothesis-driven and interdisciplinary, thus shining light into the black box of interactions belowground.
IT vendor selection model by using structural equation model & analytical hierarchy process
NASA Astrophysics Data System (ADS)
Maitra, Sarit; Dominic, P. D. D.
2012-11-01
Selecting and evaluating the right vendors is imperative for an organization's global marketplace competitiveness. Improper selection and evaluation of potential vendors can dwarf an organization's supply chain performance. Numerous studies have demonstrated that firms consider multiple criteria when selecting key vendors. This research intends to develop a new hybrid model for vendor selection process with better decision making. The new proposed model provides a suitable tool for assisting decision makers and managers to make the right decisions and select the most suitable vendor. This paper proposes a Hybrid model based on Structural Equation Model (SEM) and Analytical Hierarchy Process (AHP) for long-term strategic vendor selection problems. The five steps framework of the model has been designed after the thorough literature study. The proposed hybrid model will be applied using a real life case study to assess its effectiveness. In addition, What-if analysis technique will be used for model validation purpose.
The Cusp Catastrophe Model as Cross-Sectional and Longitudinal Mixture Structural Equation Models
Chow, Sy-Miin; Witkiewitz, Katie; Grasman, Raoul P. P. P.; Maisto, Stephen A.
2015-01-01
Catastrophe theory (Thom, 1972, 1993) is the study of the many ways in which continuous changes in a system’s parameters can result in discontinuous changes in one or several outcome variables of interest. Catastrophe theory–inspired models have been used to represent a variety of change phenomena in the realm of social and behavioral sciences. Despite their promise, widespread applications of catastrophe models have been impeded, in part, by difficulties in performing model fitting and model comparison procedures. We propose a new modeling framework for testing one kind of catastrophe model — the cusp catastrophe model — as a mixture structural equation model (MSEM) when cross-sectional data are available; or alternatively, as an MSEM with regime-switching (MSEM-RS) when longitudinal panel data are available. The proposed models and the advantages offered by this alternative modeling framework are illustrated using two empirical examples and a simulation study. PMID:25822209
Students attitude towards calculus subject: A case-study using structural equation modeling
NASA Astrophysics Data System (ADS)
Awang, Noorehan; Hamid, Nur Nadiah Abd.
2015-10-01
This study was designed to assess the attitude of Bumiputera students towards mathematics. The instrument used to measure the attitude was Test of Mathematics Related Attitude (TOMRA). This test measures students' attitudes in four criteria: normality of mathematics (N), attitudes towards mathematics inquiry (I), adoption of mathematics attitude (A) and enjoyment of mathematics lessons (E). The target population of this study was all computer science and quantitative science students who enrolled in a Calculus subject at UiTM Negeri Sembilan. Confirmatory Factor Analysis was carried out and the inter-relationship among the four criteria was analyzed using Structural Equation Modeling. The students scored high in E, moderately in A and relatively low in N and I.
2012-01-01
Background Structural equation modeling developed as a statistical melding of path analysis and factor analysis that obscured a fundamental tension between a factor preference for multiple indicators and path modeling’s openness to fewer indicators. Discussion Multiple indicators hamper theory by unnecessarily restricting the number of modeled latents. Using the few best indicators – possibly even the single best indicator of each latent – encourages development of theoretically sophisticated models. Additional latent variables permit stronger statistical control of potential confounders, and encourage detailed investigation of mediating causal mechanisms. Summary We recommend the use of the few best indicators. One or two indicators are often sufficient, but three indicators may occasionally be helpful. More than three indicators are rarely warranted because additional redundant indicators provide less research benefit than single indicators of additional latent variables. Scales created from multiple indicators can introduce additional problems, and are prone to being less desirable than either single or multiple indicators. PMID:23088287
Analyzing average and conditional effects with multigroup multilevel structural equation models
Mayer, Axel; Nagengast, Benjamin; Fletcher, John; Steyer, Rolf
2014-01-01
Conventionally, multilevel analysis of covariance (ML-ANCOVA) has been the recommended approach for analyzing treatment effects in quasi-experimental multilevel designs with treatment application at the cluster-level. In this paper, we introduce the generalized ML-ANCOVA with linear effect functions that identifies average and conditional treatment effects in the presence of treatment-covariate interactions. We show how the generalized ML-ANCOVA model can be estimated with multigroup multilevel structural equation models that offer considerable advantages compared to traditional ML-ANCOVA. The proposed model takes into account measurement error in the covariates, sampling error in contextual covariates, treatment-covariate interactions, and stochastic predictors. We illustrate the implementation of ML-ANCOVA with an example from educational effectiveness research where we estimate average and conditional effects of early transition to secondary schooling on reading comprehension. PMID:24795668
Ab initio studies of equations of state and chemical reactions of reactive structural materials
NASA Astrophysics Data System (ADS)
Zaharieva, Roussislava
The motivations for the research issues addressed in this thesis are based on the needs of the aerospace structural analysis and the design community. The specific focus is related to the characterization and shock induced chemical reactions of multi-functional structural-energetic materials that are also known as the reactive structural materials and their reaction capabilities. Usually motivation for selection of aerospace structural materials is to realize required strength characteristics and favorable strength to weight ratios. The term strength implies resistance to loads experienced during the service life of the structure, including resistance to fatigue loads, corrosion and other extreme conditions. Thus, basically the structural materials are single function materials that resist loads experienced during the service life of the structure. However, it is desirable to select materials that are capable of offering more than one basic function of strength. Very often, the second function is the capability to provide functions of sensing and actuation. In this thesis, the second function is different. The second function is the energetic characteristics. Thus, the choice of dual functions of the material are the structural characteristics and energetic characteristics. These materials are also known by other names such as the reactive material structures or dual functional structural energetic materials. Specifically the selected reactive materials include mixtures of selected metals and metal oxides that are also known as thermite mixtures, reacting intermetallic combinations and oxidizing materials. There are several techniques that are available to synthesize these structural energetic materials or reactive material structures and new synthesis techniques constitute an open research area. The focus of this thesis, however, is the characterization of chemical reactions of reactive material structures that involve two or more solids (or condensed matter). The subject of studies of the shock or thermally induced chemical reactions of the two solids comprising these reactive materials, from first principles, is a relatively new field of study. The published literature on ab initio techniques or quantum mechanics based approaches consists of the ab initio or ab initio-molecular dynamics studies in related fields that contain a solid and a gas. One such study in the literature involves a gas and a solid. This is an investigation of the adsorption of gasses such as carbon monoxide (CO) on Tungsten. The motivation for these studies is to synthesize alternate or synthetic fuel technology by Fischer-Tropsch process. In this thesis these studies are first to establish the procedure for solid-solid reaction and then to extend that to consider the effects of mechanical strain and temperature on the binding energy and chemisorptions of CO on tungsten. Then in this thesis, similar studies are also conducted on the effect of mechanical strain and temperature on the binding energies of Titanium and hydrogen. The motivations are again to understand the method and extend the method to such solid-solid reactions. A second motivation is to seek strained conditions that favor hydrogen storage and strain conditions that release hydrogen easily when needed. Following the establishment of ab initio and ab initio studies of chemical reactions between a solid and a gas, the next step of research is to study thermally induced chemical reaction between two solids (Ni+Al). Thus, specific new studies of the thesis are as follows: (1) Ab initio Studies of Binding energies associated with chemisorption of (a) CO on W surfaces (111, and 100) at elevated temperatures and strains and (b) adsorption of hydrogen in titanium base. (2) Equations of state of mixtures of reactive material structures from ab initio methods. (3) Ab initio studies of the reaction initiation, transition states and reaction products of intermetallic mixtures of (Ni+Al) at elevated temperatures and strains. (4) Press-cure synthesis of Nano-nickel and nano-aluminum based reacti
Pennig, Sibylle; Schady, Arthur
2014-01-01
In some regions the exposure to railway noise is extremely concentrated, which may lead to high residential annoyance. Nonacoustical factors contribute to these reactions, but there is limited evidence on the interrelations between the nonacoustical factors that influence railway noise annoyance. The aims of the present study were (1) to examine exposure-response relationships between long-term railway noise exposure and annoyance in a region severely affected by railway noise and (2) to determine a priori proposed interrelations between nonacoustical factors by structural equation analysis. Residents (n = 320) living close to railway tracks in the Middle Rhine Valley completed a socio-acoustic survey. Individual noise exposure levels were calculated by an acoustical simulation model for this area. The derived exposure-response relationships indicated considerably higher annoyance at the same noise exposure level than would have been predicted by the European Union standard curve, particularly for the night-time period. In the structural equation analysis, 72% of the variance in noise annoyance was explained by the noise exposure (L(den)) and nonacoustical variables. The model provides insights into several causal mechanisms underlying the formation of railway noise annoyance considering indirect and reciprocal effects. The concern about harmful effects of railway noise and railway traffic, the perceived control and coping capacity, and the individual noise sensitivity were the most important factors that influence noise annoyance. All effects of the nonacoustical factors on annoyance were mediated by the perceived control and coping capacity and additionally proposed indirect effects of the theoretical model were supported by the data. PMID:25387535
Htun, Tha Pyai; Lim, Peng Im; Ho-Lim, Sarah
2015-01-01
Objectives The aim of this study was to examine the relationships among maternal and infant characteristics, breastfeeding techniques, and exclusive breastfeeding initiation in different modes of birth using structural equation modeling approaches. Methods We examined a hypothetical model based on integrating concepts of a breastfeeding decision-making model, a breastfeeding initiation model, and a social cognitive theory among 952 mother-infant dyads. The LATCH breastfeeding assessment tool was used to evaluate breastfeeding techniques and two infant feeding categories were used (exclusive and non-exclusive breastfeeding). Results Structural equation models (SEM) showed that multiparity was significantly positively associated with breastfeeding techniques and the jaundice of an infant was significantly negatively related to exclusive breastfeeding initiation. A multigroup analysis in the SEM showed no difference between the caesarean section and vaginal delivery groups estimates of breastfeeding techniques on exclusive breastfeeding initiation. Breastfeeding techniques were significantly positively associated with exclusive breastfeeding initiation in the entire sample and in the vaginal deliveries group. However, breastfeeding techniques were not significantly associated with exclusive breastfeeding initiation in the cesarean section group. Maternal age, maternal race, gestations, birth weight of infant, and postnatal complications had no significant impacts on breastfeeding techniques or exclusive breastfeeding initiation in our study. Overall, the models fitted the data satisfactorily (GFI = 0.979–0.987; AGFI = 0.951–0.962; IFI = 0.958–0.962; CFI = 0.955–0.960, and RMSEA = 0.029–0.034). Conclusions Multiparity and jaundice of an infant were found to affect breastfeeding technique and exclusive breastfeeding initiation respectively. Breastfeeding technique was related to exclusive breastfeeding initiation according to the mode of birth. This relationship implies the importance of early effective interventions among first-time mothers with jaundice infants in improving breastfeeding techniques and promoting exclusive breastfeeding initiation. PMID:26566028
ERIC Educational Resources Information Center
Ellison, William D.; Levy, Kenneth N.
2012-01-01
Using exploratory structural equation modeling and multiple regression, we examined the factor structure and criterion relations of the primary scales of the Inventory of Personality Organization (IPO; Kernberg & Clarkin, 1995) in a nonclinical sample. Participants (N = 1,260) completed the IPO and measures of self-concept clarity, defenses,…
NASA Astrophysics Data System (ADS)
Maslov, V. P.; Shafarevich, A. I.
2006-12-01
Asymptotic solutions of the Navier-Stokes equations describing three-phase coherent structures of the Taylor scale are constructed. These equations are related to topological invariants of the Liouville foliations on the three-dimensional torus into two-dimensional tori. The solutions turn out to be unstable with respect to small-scale perturbations, which finally leads to the appearance of perturbations of Kolmogorov scale. The flicker noise occurs at the corresponding frequencies.
NASA Astrophysics Data System (ADS)
Saccomandi, Giuseppe; Vitolo, Raffaele
2014-08-01
Using the theory of 1 + 1 hyperbolic systems we put in perspective the mathematical and geometrical structure of the celebrated circularly polarized waves solutions for isotropic hyperelastic materials determined by Carroll [Acta Mechanica 3, 167-181 (1967)]. We show that a natural generalization of this class of solutions yields an infinite family of linear solutions for the equations of isotropic elastodynamics. Moreover, we determine a huge class of hyperbolic partial differential equations having the same property of the shear wave system. Restricting the attention to the usual first order asymptotic approximation of the equations determining transverse waves we provide the complete integration of this system using generalized symmetries.
Measurement Services Association Questionnaire Results.
ERIC Educational Resources Information Center
Wood, Lewis J.; Gillis, Rod
This paper presents the results of a questionnaire sent to 211 Measurement Services Association members. Sixty-four centers responded. The main purpose of the questionnaire was to find out what hardware and software are used by testing centers throughout the country. Results indicate that 52 institutions use mainframe computers, 50 use…
The Situational Outlook Questionnaire: assessing the context for change.
Isaksen, Scott G
2007-04-01
The Situational Outlook Questionnaire has been in use for many years as an assessment of the climate that supports change, innovation, and creativity. This study reports the descriptive statistics, internal consistency, factor structure, and other psychometric results from a sample of 4,730 respondents. Further areas for improvement of the questionnaire and assessment approach are identified. PMID:17564220
Wills, John M; Mattsson, Ann E
2012-06-06
Brooks, Johansson, and Skriver, using the LMTO-ASA method and considerable insight, were able to explain many of the ground state properties of the actinides. In the many years since this work was done, electronic structure calculations of increasing sophistication have been applied to actinide elements and compounds, attempting to quantify the applicability of DFT to actinides and actinide compounds and to try to incorporate other methodologies (i.e. DMFT) into DFT calculations. Through these calculations, the limits of both available density functionals and ad hoc methodologies are starting to become clear. However, it has also become clear that approximations used to incorporate relativity are not adequate to provide rigorous tests of the underlying equations of DFT, not to mention ad hoc additions. In this talk, we describe the result of full-potential LMTO calculations for the elemental actinides, comparing results obtained with a full Dirac basis with those obtained from scalar-relativistic bases, with and without variational spin-orbit. This comparison shows that the scalar relativistic treatment of actinides does not have sufficient accuracy to provide a rigorous test of theory and that variational spin-orbit introduces uncontrolled errors in the results of electronic structure calculations on actinide elements.
Gardiner, Lesley; Akintola, Adebayo; Chen, Gang; Catania, Jeffrey M.; Vaidya, Vishal; Burghardt, Robert C.; Bonventre, Joseph V.; Trzeciakowski, Jerome; Parrish, Alan R.
2012-01-01
Background Chronic kidney disease (CKD) is a major public health problem, and despite continued research in the field, there is still a need to identify both biomarkers of risk and progression, as well as potential therapeutic targets. Structural equation modeling (SEM) is a family of statistical techniques that has been utilized in the fields of sociology and psychology for many years; however, its utilization in the biological sciences is relatively novel. SEM's ability to investigate complex relationships in an efficient, single model could be utilized to understand the progression of CKD, as well as to develop a predictive model to assess kidney status in the patient. Methods Fischer 344 rats were fed either an ad libitum diet or a calorically restricted diet, and a time-course study of kidney structure and function was performed. EQS, a SEM software package, was utilized to generate five CKD models of the Fisher 344 rat and identify relationships between measured variables and estimates of kidney damage and kidney function. Results All models identified strong relationships between a biomarker for CKD, kidney injury molecule-1 (Kim-1) and kidney damage, in the Fischer 344 rat CKD model. Models also indicate a strong relationship between age and renal damage and dysfunction. Conclusion SEM can be used to model CKD and could be useful to examine biomarkers in CKD patients. PMID:22269876
Parallel Workflows for Data-Driven Structural Equation Modeling in Functional Neuroimaging
Kenny, Sarah; Andric, Michael; Boker, Steven M.; Neale, Michael C.; Wilde, Michael; Small, Steven L.
2009-01-01
We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406
Swedler, David I; Verma, Santosh K; Huang, Yueng-Hsiang; Lombardi, David A; Chang, Wen-Ruey; Brennan, Melayne; Courtney, Theodore K
2015-01-01
Objective Safety climate has previously been associated with increasing safe workplace behaviours and decreasing occupational injuries. This study seeks to understand the structural relationship between employees’ perceptions of safety climate, performing a safety behaviour (ie, wearing slip-resistant shoes) and risk of slipping in the setting of limited-service restaurants. Methods At baseline, we surveyed 349 employees at 30 restaurants for their perceptions of their safety training and management commitment to safety as well as demographic data. Safety performance was identified as wearing slip-resistant shoes, as measured by direct observation by the study team. We then prospectively collected participants’ hours worked and number of slips weekly for the next 12?weeks. Using a confirmatory factor analysis, we modelled safety climate as a higher order factor composed of previously identified training and management commitment factors. Results The 349 study participants experienced 1075 slips during the 12-week follow-up. Confirmatory factor analysis supported modelling safety climate as a higher order factor composed of safety training and management commitment. In a structural equation model, safety climate indirectly affected prospective risk of slipping through safety performance, but no direct relationship between safety climate and slips was evident. Conclusions Results suggest that safety climate can reduce workplace slips through performance of a safety behaviour as well as suggesting a potential causal mechanism through which safety climate can reduce workplace injuries. Safety climate can be modelled as a higher order factor composed of safety training and management commitment. PMID:25710968
Hoyle, Rick H; Gottfredson, Nisha C
2015-10-01
When the goal of prevention research is to capture in statistical models some measure of the dynamic complexity in structures and processes implicated in problem behavior and its prevention, approaches such as multilevel modeling (MLM) and structural equation modeling (SEM) are indicated. Yet the assumptions that must be satisfied if these approaches are to be used responsibly raise concerns regarding their use in prevention research involving smaller samples. In this article, we discuss in nontechnical terms the role of sample size in MLM and SEM and present findings from the latest simulation work on the performance of each approach at sample sizes typical of prevention research. For each statistical approach, we draw from extant simulation studies to establish lower bounds for sample size (e.g., MLM can be applied with as few as ten groups comprising ten members with normally distributed data, restricted maximum likelihood estimation, and a focus on fixed effects; sample sizes as small as N?=?50 can produce reliable SEM results with normally distributed data and at least three reliable indicators per factor) and suggest strategies for making the best use of the modeling approach when N is near the lower bound. PMID:24752569
Parallel workflows for data-driven structural equation modeling in functional neuroimaging.
Kenny, Sarah; Andric, Michael; Boker, Steven M; Neale, Michael C; Wilde, Michael; Small, Steven L
2009-01-01
We present a computational framework suitable for a data-driven approach to structural equation modeling (SEM) and describe several workflows for modeling functional magnetic resonance imaging (fMRI) data within this framework. The Computational Neuroscience Applications Research Infrastructure (CNARI) employs a high-level scripting language called Swift, which is capable of spawning hundreds of thousands of simultaneous R processes (R Development Core Team, 2008), consisting of self-contained SEMs, on a high performance computing system (HPC). These self-contained R processing jobs are data objects generated by OpenMx, a plug-in for R, which can generate a single model object containing the matrices and algebraic information necessary to estimate parameters of the model. With such an infrastructure in place a structural modeler may begin to investigate exhaustive searches of the model space. Specific applications of the infrastructure, statistics related to model fit, and limitations are discussed in relation to exhaustive SEM. In particular, we discuss how workflow management techniques can help to solve large computational problems in neuroimaging. PMID:19876406
On the structure of the master equation for a two-level system coupled to a thermal bath
NASA Astrophysics Data System (ADS)
de Vega, Inés
2015-04-01
We derive a master equation from the exact stochastic Liouville-von-Neumann (SLN) equation (Stockburger and Grabert 2002 Phys. Rev. Lett. 88 170407). The latter depends on two correlated noises and describes exactly the dynamics of an oscillator (which can be either harmonic or present an anharmonicity) coupled to an environment at thermal equilibrium. The newly derived master equation is obtained by performing analytically the average over different noise trajectories. It is found to have a complex hierarchical structure that might be helpful to explain the convergence problems occurring when performing numerically the stochastic average of trajectories given by the SLN equation (Koch et al 2008 Phys. Rev. Lett. 100 230402, Koch 2010 PhD thesis Fakultät Mathematik und Naturwissenschaften der Technischen Universitat Dresden).
Alcaraz, Saül; Viladrich, Carme; Torregrosa, Miquel
2013-01-01
When assessing team environments in youth sport, participants often spend substantial time responding to lots of items in questionnaires, causing a lack of efficiency (i.e. time and effort) and a decrease of data quality. The purpose of this work was to create short-forms of the questionnaires PeerMCYSQ, SCQPeer, TEOSQ, and also to analyse the existing short-form of the SCQCoach. In Study 1 we developed the short-forms of the instruments. We shortened the questionnaires by using both theory driven and data-driven criteria. In Study 2, we used also qualitative and quantitative data with the aim of validating the short-forms. Finally, in Study 3 we tested the last version of the short-forms and sought evidences concerning their criterion validity. The results showed evidence that supports the psychometric merit of these short-forms: (a) significantly less missing values were obtained; (b) all the factors obtained alpha values above .70; (c) confirmatory factor analyses demonstrated that the short-forms fitted the hypothesized models well; (d) correlations between variables were coherent with expectations, and (e) structural equation modeling results showed significant paths consistent with previous literature. On average, our participants only spent a third of the time used to complete the original questionnaires. PMID:24230940
DIVING QUESTIONNAIRE University of Florida
Slatton, Clint
. Number of months since last active diving period: ______ months Bottom time using SCUBA: ______ hours Number of dives using SCUBA: ______ Average depth: ______ feet. Maximum depth: ______ feet RecreationalDIVING QUESTIONNAIRE University of Florida Division of Environmental Health and Safety Diving
A General Questionnaire Analysis Program
ERIC Educational Resources Information Center
Aiken, Lewis R.
1978-01-01
A general FORTRAN computer program for analyzing categorical or frequency data obtained from questionnaires is described. A variety of descriptive statistics, chi square, Kendall's tau and Cramer's statistic are provided. (Author/JKS)
Physical Activity Questionnaire Search Results
The Brunel Lifestyle Physical Activity Questionnaire a4 If you add together each session of pre-planned physical activity that you engage in during a normal week, how much time would you estimate that you spend in total?
Cook, Andrew J; Brawer, Peter A; Vowles, Kevin E
2006-04-01
The cognitive-behavioral, fear-avoidance (FA) model of chronic pain (Vlaeyen JWS, Kole-Snijders AMJ, Boeren RGB, van Eek H. Fear of movement/(re)injury in chronic low back pain and its relation to behavioral performance. Pain 1995a;62:363-72) has found broad empirical support, but its multivariate, predictive relationships have not been uniformly validated. Applicability of the model across age groups of chronic pain patients has also not been tested. Goals of this study were to validate the predictive relationships of the multivariate FA model using structural equation modeling and to evaluate the factor structure of the Tampa Scale of Kinesiophobia (TSK), levels of pain-related fear, and fit of the FA model across three age groups: young (< or =40), middle-aged (41-54), and older (> or =55) adults. A heterogeneous sample of 469 chronic pain patients provided ratings of catastrophizing, pain-related fear, depression, perceived disability, and pain severity. Using a confirmatory approach, a 2-factor, 13-item structure of the TSK provided the best fit and was invariant across age groups. Older participants were found to have lower TSK fear scores than middle-aged participants for both factors (FA, Harm). A modified version of the Vlaeyen JWS, Kole-Snijders AMJ, Boeren RGB, van Eek H (Fear of movement/(re)injury in chronic low back pain and its relation to behavioral performance. Pain 1995a;62:363-72.) FA model provided a close fit to the data (chi(2)(29)=42.0, p>0.05, GFI=0.98, AGFI=0.97, CFI=0.99, RMSEA=0.031 (90% CI 0.000-0.050), p close fit=0.95). Multigroup analyses revealed significant differences in structural weights for older vs. middle-aged participants. For older chronic pain patients, a stronger mediating role for pain-related fear was supported. Results are consistent with a FA model of chronic pain, while indicating some important age group differences in this model and in levels of pain-related fear. Longitudinal testing of the multivariate model is recommended. PMID:16495008
ERIC Educational Resources Information Center
de Guzman, Allan B.; Jimenez, Benito Christian B.; Jocson, Kathlyn P.; Junio, Aileen R.; Junio, Drazen E.; Jurado, Jasper Benjamin N.; Justiniano, Angela Bianca F.
2013-01-01
Anchored on the key constucts of Ajzen's Theory of Planned Behavior (1985), this paper seeks to test a model that explores the influence of knowledge, attitude, and caring behavior on nursing students' behavioral intention toward geriatric care. A five-part survey-questionnaire was administered to 839 third and fourth year nursing students from a…
ERIC Educational Resources Information Center
Rowe, Kenneth J.; Hill, Peter W.
1998-01-01
Illustrates an approach to modeling educational effectiveness in classrooms by combining multilevel analysis and structural equation modeling in a two-step process. Data from a longitudinal study of 4,558 students in 334 class groups show how progress can be accounted for by the grouping effects of students within classes and schools. (SLD)
ERIC Educational Resources Information Center
Thompson, Bruce
This paper provides an introduction to basic issues concerning structural equation modeling (SEM), a research methodology increasingly being used in social science research. First, seven key issues that must be considered in any SEM analysis are explained. These include matrix of associations to analyze, model identification, parameter estimation…
ERIC Educational Resources Information Center
Furlow, Carolyn F.; Beretvas, S. Natasha
2005-01-01
Three methods of synthesizing correlations for meta-analytic structural equation modeling (SEM) under different degrees and mechanisms of missingness were compared for the estimation of correlation and SEM parameters and goodness-of-fit indices by using Monte Carlo simulation techniques. A revised generalized least squares (GLS) method for…
ERIC Educational Resources Information Center
In'nami, Yo; Koizumi, Rie
2013-01-01
The importance of sample size, although widely discussed in the literature on structural equation modeling (SEM), has not been widely recognized among applied SEM researchers. To narrow this gap, we focus on second language testing and learning studies and examine the following: (a) Is the sample size sufficient in terms of precision and power of…
ERIC Educational Resources Information Center
Stephens, Ana C.; Knuth, Eric J.; Blanton, Maria L.; Isler, Isil; Gardiner, Angela Murphy; Marum, Tim
2013-01-01
This paper reports results from a written assessment given to 290 third-, fourth-, and fifth-grade students prior to any instructional intervention. We share and discuss students' responses to items addressing their understanding of equation structure and the meaning of the equal sign. We found that many students held an operational conception of…
ERIC Educational Resources Information Center
Holland, Paul W.
D. B. Rubin's model for causal inference in experiments and observational studies is enlarged to analyze the problem of "causes causing causes" and is compared to path analysis and recursive structural equations models. A special quasiexperimental design, the encouragement design, is used to give concreteness to the discussion by focusing on the…
ERIC Educational Resources Information Center
Jen, Tsung-Hau; Lee, Che-Di; Chien, Chin-Lung; Hsu, Ying-Shao; Chen, Kuan-Ming
2013-01-01
Based on the Trends in International Mathematics and Science Study 2007 study and a follow-up national survey, data for 3,901 Taiwanese grade 8 students were analyzed using structural equation modeling to confirm a social-relation-based affection-driven model (SRAM). SRAM hypothesized relationships among students' perceived social relationships in…
ERIC Educational Resources Information Center
Xie, Qin; Andrews, Stephen
2013-01-01
This study introduces Expectancy-value motivation theory to explain the paths of influences from perceptions of test design and uses to test preparation as a special case of washback on learning. Based on this theory, two conceptual models were proposed and tested via Structural Equation Modeling. Data collection involved over 870 test takers of…
ERIC Educational Resources Information Center
Santos-George, Arlene A.
2012-01-01
This dissertation empirically tested Tinto's student integration theory through structural equation modeling using a national sample of 2,847 first-time entering community college students. Tinto theorized that the more academically and socially integrated a student is to the college environment, the more likely the student will persist…
ERIC Educational Resources Information Center
Huang, Heng-Tsung Danny
2010-01-01
Thus far, few research studies have examined the practice of integrated speaking test tasks in the field of second/foreign language oral assessment. This dissertation utilized structural equation modeling (SEM) and qualitative techniques to explore the relationships among topical knowledge, anxiety, and integrated speaking test performance and to…
ERIC Educational Resources Information Center
Glockner-Rist, Angelika; Hoijtink, Herbert
2003-01-01
Both structural equation modeling (SEM) and item response theory (IRT) can be used for factor analysis of dichotomous item responses. In this case, the measurement models of both approaches are formally equivalent. They were refined within and across different disciplines, and make complementary contributions to central measurement problems…
ERIC Educational Resources Information Center
Enders, Craig K.
2002-01-01
Proposed a method for extending the Bollen-Stine bootstrap model (K. Bollen and R. Stine, 1992) fit to structural equation models with missing data. Developed a Statistical Analysis System macro program to implement this procedure, and assessed its usefulness in a simulation. The new method yielded model rejection rates close to the nominal 5%…
The Michigan data needs questionnaire
NASA Technical Reports Server (NTRS)
Hill-Rowley, R.
1981-01-01
The data needs questionnaire is an element in the project design study for the Michigan Resource Inventory Act and is aimed at gathering information on what inventory information is required by land use planners throughout the state. Analysis of questionnaire responses is discussed. Some information on current use categories was tabulated. The respondents selected a broad range of categories at all levels of detail. Those most frequently indicated were urban categories.
Mann, Sarah L; Selby, Edward A; Bates, Marsha E; Contrada, Richard J
2015-10-01
High frequency heart rate variability (HRV) is a measure of neurocardiac communication thought to reflect predominantly parasympathetic cardiac regulation. Low HRV has been associated empirically with clinical and subclinical levels of anxiety and depression and, more recently, high levels of HRV have been associated with better performance on some measures of executive functioning (EF). These findings have offered support for theories proposing HRV as an index measure of a broad, self-regulatory capacity underlying aspects of emotion regulation and executive control. This study sought to test that proposition by using a structural equation modeling approach to examine the relationships of HRV to negative affect (NA) and EF in a large sample of U.S. adults ages 30s-80s. HRV was modeled as a predictor of an NA factor (self-reported trait anxiety and depression symptoms) and an EF factor (performance on three neuropsychological tests tapping facets of executive abilities). Alternative models also were tested to determine the utility of HRV for predicting NA and EF, with and without statistical control of demographic and health-related covariates. In the initial structural model, HRV showed a significant positive relationship to EF and a nonsignificant relationship to NA. In a covariate-adjusted model, HRV's associations with both constructs were nonsignificant. Age emerged as the only significant predictor of NA and EF in the final model, showing inverse relationships to both. Findings may reflect population and methodological differences from prior research; they also suggest refinements to the interpretations of earlier findings and theoretical claims regarding HRV. PMID:26168884
Pediatric Health-Related Quality of Life: A Structural Equation Modeling Approach
Villalonga-Olives, Ester; Kawachi, Ichiro; Almansa, Josué; Witte, Claudia; Lange, Benjamin; Kiese-Himmel, Christiane; von Steinbüchel, Nicole
2014-01-01
Objectives One of the most referenced theoretical frameworks to measure Health Related Quality of Life (HRQoL) is the Wilson and Cleary framework. With some adaptions this framework has been validated in the adult population, but has not been tested in pediatric populations. Our goal was to empirically investigate it in children. Methods The contributory factors to Health Related Quality of Life that we included were symptom status (presence of chronic disease or hospitalizations), functional status (developmental status), developmental aspects of the individual (social-emotional) behavior, and characteristics of the social environment (socioeconomic status and area of education). Structural equation modeling was used to assess the measurement structure of the model in 214 German children (3–5 years old) participating in a follow-up study that investigates pediatric health outcomes. Results Model fit was ?2?=?5.5; df?=?6; p?=?0.48; SRMR ?=?0.01. The variance explained of Health Related Quality of Life was 15%. Health Related Quality of Life was affected by the area education (i.e. where kindergartens were located) and development status. Developmental status was affected by the area of education, socioeconomic status and individual behavior. Symptoms did not affect the model. Conclusions The goodness of fit and the overall variance explained were good. However, the results between children' and adults' tests differed and denote a conceptual gap between adult and children measures. Indeed, there is a lot of variety in pediatric Health Related Quality of Life measures, which represents a lack of a common definition of pediatric Health Related Quality of Life. We recommend that researchers invest time in the development of pediatric Health Related Quality of Life theory and theory based evaluations. PMID:25415751
Yu, Ge; Sessions, John G; Fu, Yu; Wall, Martin
2015-10-01
We investigated the reciprocal relationship between individual social capital and perceived mental and physical health in the UK. Using data from the British Household Panel Survey from 1991 to 2008, we fitted cross-lagged structural equation models that include three indicators of social capital vis. social participation, social network, and loneliness. Given that multiple measurement points (level 1) are nested within individuals (level 2), we also applied a multilevel model to allow for residual variation in the outcomes at the occasion and individual levels. Controlling for gender, age, employment status, educational attainment, marital status, household wealth, and region, our analyses suggest that social participation predicts subsequent change in perceived mental health, and vice versa. However, whilst loneliness is found to be significantly related to perceived mental and physical health, reciprocal causality is not found for perceived mental health. Furthermore, we find evidence for reverse effects with both perceived mental and physical health appearing to be the dominant causal factor with respect to the prospective level of social network. Our findings thus shed further light on the importance of social participation and social inclusion in health promotion and aid the development of more effective public health policies in the UK. PMID:26277109
Lu, Huancai; Wu, Sean F
2009-03-01
The vibroacoustic responses of a highly nonspherical vibrating object are reconstructed using Helmholtz equation least-squares (HELS) method. The objectives of this study are to examine the accuracy of reconstruction and the impacts of various parameters involved in reconstruction using HELS. The test object is a simply supported and baffled thin plate. The reason for selecting this object is that it represents a class of structures that cannot be exactly described by the spherical Hankel functions and spherical harmonics, which are taken as the basis functions in the HELS formulation, yet the analytic solutions to vibroacoustic responses of a baffled plate are readily available so the accuracy of reconstruction can be checked accurately. The input field acoustic pressures for reconstruction are generated by the Rayleigh integral. The reconstructed normal surface velocities are validated against the benchmark values, and the out-of-plane vibration patterns at several natural frequencies are compared with the natural modes of a simply supported plate. The impacts of various parameters such as number of measurement points, measurement distance, location of the origin of the coordinate system, microphone spacing, and ratio of measurement aperture size to the area of source surface of reconstruction on the resultant accuracy of reconstruction are examined. PMID:19275312
Network inference of AP pattern formation system in D.melanogaster by structural equation modeling
NASA Astrophysics Data System (ADS)
Aburatani, S.; Toh, H.
2014-03-01
Within the field of systems biology, revealing the control systems functioning during embryogenesis is an important task. To clarify the mechanisms controlling sequential events, the relationships between various factors and the expression of specific genes should be determined. In this study, we applied a method based on Structural Equation Modeling (SEM), combined with factor analysis. SEM can include the latent variables within the constructed model and infer the relationships among the latent and observed variables, as a network model. We improved a method for the construction of initial models for the SEM calculation, and applied our approach to estimate the regulatory network for Antero-Posterior (AP) pattern formation in D. melanogaster embryogenesis. In this new approach, we combined cross-correlation and partial correlation to summarize the temporal information and to extract the direct interactions from the gene expression profiles. In the inferred model, 18 transcription factor genes were regulated by not only the expression of other genes, but also the estimated factors. Since each factor regulated the same type of genes, these factors were considered to be involved in maternal effects or spatial morphogen distributions. The interpretation of the inferred network model allowed us to reveal the regulatory mechanism for the patterning along the head to tail axis in D. melanogaster.
Modelling Pathways to Rubisco Degradation: A Structural Equation Network Modelling Approach
Tétard-Jones, Catherine; Gatehouse, Angharad M. R.; Cooper, Julia; Leifert, Carlo; Rushton, Steven
2014-01-01
‘Omics analysis (transcriptomics, proteomics) quantifies changes in gene/protein expression, providing a snapshot of changes in biochemical pathways over time. Although tools such as modelling that are needed to investigate the relationships between genes/proteins already exist, they are rarely utilised. We consider the potential for using Structural Equation Modelling to investigate protein-protein interactions in a proposed Rubisco protein degradation pathway using previously published data from 2D electrophoresis and mass spectrometry proteome analysis. These informed the development of a prior model that hypothesised a pathway of Rubisco Large Subunit and Small Subunit degradation, producing both primary and secondary degradation products. While some of the putative pathways were confirmed by the modelling approach, the model also demonstrated features that had not been originally hypothesised. We used Bayesian analysis based on Markov Chain Monte Carlo simulation to generate output statistics suggesting that the model had replicated the variation in the observed data due to protein-protein interactions. This study represents an early step in the development of approaches that seek to enable the full utilisation of information regarding the dynamics of biochemical pathways contained within proteomics data. As these approaches gain attention, they will guide the design and conduct of experiments that enable ‘Omics modelling to become a common place practice within molecular biology. PMID:24498339
Lee, Sik-Yum; Song, Xin-Yuan
2004-05-01
Missing data are very common in behavioural and psychological research. In this paper, we develop a Bayesian approach in the context of a general nonlinear structural equation model with missing continuous and ordinal categorical data. In the development, the missing data are treated as latent quantities, and provision for the incompleteness of the data is made by a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. We show by means of a simulation study that the Bayesian estimates are accurate. A Bayesian model comparison procedure based on the Bayes factor and path sampling is proposed. The required observations from the posterior distribution for computing the Bayes factor are simulated by the hybrid algorithm in Bayesian estimation. Our simulation results indicate that the correct model is selected more frequently when the incomplete records are used in the analysis than when they are ignored. The methodology is further illustrated with a real data set from a study concerned with an AIDS preventative intervention for Filipina sex workers. PMID:15171804
La Peyre, M.K.; Mendelssohn, I.A.; Reams, M.A.; Templet, P.H.; Grace, J.B.
2001-01-01
Integrated management and policy models suggest that solutions to environmental issues may be linked to the socioeconomic and political Characteristics of a nation. In this study, we empirically explore these suggestions by applying them to the wetland management activities of nations. Structural equation modeling was used to evaluate a model of national wetland management effort and one of national wetland protection. Using five predictor variables of social capital, economic capital, environmental and political characteristics, and land-use pressure, the multivariate models were able to explain 60% of the variation in nations' wetland protection efforts based on data from 90 nations, as defined by level of participation, in the international wetland convention. Social capital had the largest direct effect on wetland protection efforts, suggesting that increased social development may eventually lead to better wetland protection. In contrast, increasing economic development had a negative linear relationship with wetland protection efforts, suggesting the need for explicit wetland protection programs as nations continue to focus on economic development. Government, environmental characteristics, and land-use pressure also had a positive direct effect on wetland protection, and mediated the effect of social capital on wetland protection. Explicit wetland protection policies, combined with a focus on social development, would lead to better wetland protection at the national level.
Fyhri, Aslak; Klaeboe, Ronny
2009-01-01
The proposed effect of road traffic noise on hypertension and ischemic heart disease finds mixed empirical support. One problem with many studies is that the directions of the causal relationships are not identified. This is often the case when cross-sectional data and multivariate regression models are utilised. The aim of the study was to explore the relationship between road traffic noise and health. More specifically the relationships between noise complaints, noise sensitivity and subjectively reported hypertension and heart problems were investigated. 1842 respondents in Oslo, Norway were interviewed about their experience of the local environment and their subjective health complaints. The interviews were conducted as part of two surveys. Individual measures of air pollution (NO(2)) and noise (Lden) were calculated. The data were analysed using Structural Equation Models. Only sensitivity to noise is related to hypertension and chest pain. No relationships between noise exposure and health complaints were identified. Rather than noise being the causal agent leading to health problems, the results suggest that the noise-health relationships in these studies may be spurious. It is conceivable that individual vulnerability is reflected both in ill health and in being sensitive to noise. The benefit of including more contextual variables in a model of noise-health relationships is supported. PMID:18823662
Determinants of Phubbing, Which is the Sum of Many Virtual Addictions: A Structural Equation Model
Karada?, Engi?n; Tosunta?, ?ule Betül; Erzen, Evren; Duru, Pinar; Bostan, Nalan; ?ahi?n, Berrak Mizrak; Çulha, ?LKAY; Babada?, Burcu
2015-01-01
Background and Aims Phubbing can be described as an individual looking at his or her mobile phone during a conversation with other individuals, dealing with the mobile phone and escaping from interpersonal communication. In this research, determinants of phubbing behavior were investigated; in addition, the effects of gender, smart phone ownership and social media membership were tested as moderators. Methods To examine the cause–effect relations among the variables of the theoretical model, the research employs a correlational design. Participants were 409 university students who were selected via random sampling. Phubbing was obtained via the scales featuring mobile phone addiction, SMS addiction, internet addiction, social media addiction and game addiction. The obtained data were analyzed using a correlation analysis, multiple linear regression analysis and structural equation model. Results The results showed that the most important determinants of phubbing behavior are mobile phone, SMS, social media and internet addictions. Discussion Although the findings show that the highest correlation value explaining phubbing is a mobile phone addiction, the other correlation values reflect a dependency on the phone. Conclusions There is an increasing tendency towards mobile phone use, and this tendency prepares the basis of phubbing. PMID:26014669
2013-01-01
Background To improve quality of life (QOL) in patients with multiple sclerosis (MS), it is important to decrease disability and prevent relapse. The aim of this study was to examine the causal and mutual relationships contributing to QOL in Japanese patients with MS, develop path diagrams, and explore interventions with the potential to improve patient QOL. Methods Data of 163 Japanese MS patients were obtained using the Functional Assessment of MS (FAMS) and Nottingham Adjustment Scale-Japanese version (NAS-J) tests, as well as four additional factors that affect QOL (employment status, change of income, availability of disease information, and communication with medical staff). Data were then used in structural equation modeling to develop path diagrams for factors contributing to QOL. Results The Expanded Disability Status Scale (EDSS) score had a significant effect on the total FAMS score. Although EDSS negatively affected the FAMS symptom score, NAS-J subscale scores of anxiety/depression and acceptance were positively related to the FAMS symptom score. Changes in employment status after MS onset negatively affected all NAS-J scores. Knowledge of disease information improved the total NAS-J score, which in turn improved many FAMS subscale scores. Communication with doctors and nurses directly and positively affected some FAMS subscale scores. Conclusions Disability and change in employment status decrease patient QOL. However, the present findings suggest that other factors, such as acquiring information on MS and communicating with medical staff, can compensate for the worsening of QOL. PMID:23339479
Structural equation modeling of the inflammatory response to traffic air pollution
Baja, Emmanuel S.; Schwartz, Joel D.; Coull, Brent A.; Wellenius, Gregory A.; Vokonas, Pantel S.; Suh, Helen H.
2015-01-01
Several epidemiological studies have reported conflicting results on the effect of traffic-related pollutants on markers of inflammation. In a Bayesian framework, we examined the effect of traffic pollution on inflammation using structural equation models (SEMs). We studied measurements of C-reactive protein (CRP), soluble vascular cell adhesion molecule-1 (sVCAM-1), and soluble intracellular adhesion molecule-1 (sICAM-1) for 749 elderly men from the Normative Aging Study. Using repeated measures SEMs, we fit a latent variable for traffic pollution that is reflected by levels of black carbon, carbon monoxide, nitrogen monoxide and nitrogen dioxide to estimate its effect on a latent variable for inflammation that included sICAM-1, sVCAM-1 and CRP. Exposure periods were assessed using 1-, 2-, 3-, 7-, 14- and 30-day moving averages previsit. We compared our findings using SEMs with those obtained using linear mixed models. Traffic pollution was related to increased inflammation for 3-, 7-, 14- and 30-day exposure periods. An inter-quartile range increase in traffic pollution was associated with a 2.3% (95% posterior interval (PI): 0.0–4.7%) increase in inflammation for the 3-day moving average, with the most significant association observed for the 30-day moving average (23.9%; 95% PI: 13.9–36.7%). Traffic pollution adversely impacts inflammation in the elderly. SEMs in a Bayesian framework can comprehensively incorporate multiple pollutants and health outcomes simultaneously in air pollution–cardiovascular epidemiological studies. PMID:23232970
Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.
2015-01-01
Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb. This study used Monte Carlo data simulation techniques to evaluate sample size requirements for common applied SEMs. Across a series of simulations, we systematically varied key model properties, including number of indicators and factors, magnitude of factor loadings and path coefficients, and amount of missing data. We investigated how changes in these parameters affected sample size requirements with respect to statistical power, bias in the parameter estimates, and overall solution propriety. Results revealed a range of sample size requirements (i.e., from 30 to 460 cases), meaningful patterns of association between parameters and sample size, and highlight the limitations of commonly cited rules-of-thumb. The broad “lessons learned” for determining SEM sample size requirements are discussed. PMID:25705052
ERIC Educational Resources Information Center
Furnham, Adrian; Guenole, Nigel; Levine, Stephen Z.; Chamorro-Premuzic, Tomas
2013-01-01
This study presents new analyses of NEO Personality Inventory-Revised (NEO-PI-R) responses collected from a large British sample in a high-stakes setting. The authors show the appropriateness of the five-factor model underpinning these responses in a variety of new ways. Using the recently developed exploratory structural equation modeling (ESEM)…
Löffler, Antje; Luck, Tobias; Then, Francisca S.; Sikorski, Claudia; Kovacs, Peter; Böttcher, Yvonne; Breitfeld, Jana; Tönjes, Anke; Horstmann, Annette; Löffler, Markus; Engel, Christoph; Thiery, Joachim; Villringer, Arno; Stumvoll, Michael; Riedel-Heller, Steffi G.
2015-01-01
The Three-Factor-Eating-Questionnaire (TFEQ) is an established instrument to assess eating behaviour. Analysis of the TFEQ-factor structure was based on selected, convenient and clinical samples so far. Aims of this study were (I) to analyse the factor structure of the German version of the TFEQ and (II)—based on the refined factor structure—to examine the association between eating behaviour and the body mass index (BMI) in a general population sample of 3,144 middle-aged and older participants (40–79 years) of the ongoing population based cohort study of the Leipzig Research Center for Civilization Diseases (LIFE Health Study). The factor structure was examined in a split-half analysis with both explorative and confirmatory factor analysis. Associations between TFEQ-scores and BMI values were tested with multiple regression analyses controlled for age, gender, and education. We found a three factor solution for the TFEQ with an ‘uncontrolled eating’, a ‘cognitive restraint’ and an ‘emotional eating’ domain including 29 of the original 51 TFEQ-items. Scores of the ‘uncontrolled eating domain’ showed the strongest correlation with BMI values (partial r = 0.26). Subjects with scores above the median in both ‘uncontrolled eating’ and ‘emotional eating’ showed the highest BMI values (mean = 29.41 kg/m²), subjects with scores below the median in all three domains showed the lowest BMI values (mean = 25.68 kg/m²; F = 72.074, p<0.001). Our findings suggest that the TFEQ is suitable to identify subjects with specific patterns of eating behaviour that are associated with higher BMI values. Such information may help health care professionals to develop and implement more tailored interventions for overweight and obese individuals. PMID:26230264
Laughlin, D.C.; Abella, S.R.; Covington, W.W.; Grace, J.B.
2007-01-01
Question: How are the effects of mineral soil properties on understory plant species richness propagated through a network of processes involving the forest overstory, soil organic matter, soil nitrogen, and understory plant abundance? Location: North-central Arizona, USA. Methods: We sampled 75 0.05-ha plots across a broad soil gradient in a Pinus ponderosa (ponderosa pine) forest ecosystem. We evaluated multivariate models of plant species richness using structural equation modeling. Results: Richness was highest at intermediate levels of understory plant cover, suggesting that both colonization success and competitive exclusion can limit richness in this system. We did not detect a reciprocal positive effect of richness on plant cover. Richness was strongly related to soil nitrogen in the model, with evidence for both a direct negative effect and an indirect non-linear relationship mediated through understory plant cover. Soil organic matter appeared to have a positive influence on understory richness that was independent of soil nitrogen. Richness was lowest where the forest overstory was densest, which can be explained through indirect effects on soil organic matter, soil nitrogen and understory cover. Finally, model results suggest a variety of direct and indirect processes whereby mineral soil properties can influence richness. Conclusions: Understory plant species richness and plant cover in P. ponderosa forests appear to be significantly influenced by soil organic matter and nitrogen, which are, in turn, related to overstory density and composition and mineral soil properties. Thus, soil properties can impose direct and indirect constraints on local species diversity in ponderosa pine forests. ?? IAVS; Opulus Press.
A Structural Equation Model Analysis of Relationships among ENSO, Seasonal Descriptors and Wildfires
Slocum, Matthew G.; Orzell, Steve L.
2013-01-01
Seasonality drives ecological processes through networks of forcings, and the resultant complexity requires creative approaches for modeling to be successful. Recently ecologists and climatologists have developed sophisticated methods for fully describing seasons. However, to date the relationships among the variables produced by these methods have not been analyzed as networks, but rather with simple univariate statistics. In this manuscript we used structural equation modeling (SEM) to analyze a proposed causal network describing seasonality of rainfall for a site in south-central Florida. We also described how this network was influenced by the El Niño-Southern Oscillation (ENSO), and how the network in turn affected the site’s wildfire regime. Our models indicated that wet and dry seasons starting later in the year (or ending earlier) were shorter and had less rainfall. El Niño conditions increased dry season rainfall, and via this effect decreased the consistency of that season’s drying trend. El Niño conditions also negatively influenced how consistent the moistening trend was during the wet season, but in this case the effect was direct and did not route through rainfall. In modeling wildfires, our models showed that area burned was indirectly influenced by ENSO via its effect on dry season rainfall. Area burned was also indirectly reduced when the wet season had consistent rainfall, as such wet seasons allowed fewer wildfires in subsequent fire seasons. Overall area burned at the study site was estimated with high accuracy (R2 score = 0.63). In summary, we found that by using SEMs, we were able to clearly describe causal patterns involving seasonal climate, ENSO and wildfire. We propose that similar approaches could be effectively applied to other sites where seasonality exerts strong and complex forcings on ecological processes. PMID:24086670
2014-01-01
Background Epidemiological research has long observed a varying prevalence of hypertension across socioeconomic strata. However, patterns of association and underlying causal mechanisms are poorly understood in sub-Saharan Africa. Using education and income as indicators, we investigated the extent to which socioeconomic status is linked to blood pressure in the first wave of the National Income Dynamics Study — a South African longitudinal study of more than 15000 adults – and whether bio-behavioural risk factors mediate the association. Methods In a cross-sectional analysis, structural equation modelling was employed to estimate the effect of socioeconomic status on systolic and diastolic blood pressure and to assess the role of a set of bio-behavioural risk factors in explaining the observed relationships. Results After adjustment for age, race and antihypertensive treatment, higher education and income were independently associated with higher diastolic blood pressure in men. In women higher education predicted lower values of both diastolic and systolic blood pressure while higher income predicted lower systolic blood pressure. In both genders, body mass index was a strong mediator of an adverse indirect effect of socioeconomic status on blood pressure. Together with physical exercise, alcohol use, smoking and resting heart rate, body mass index therefore contributed substantially to mediation of the observed relationships in men. By contrast, in women unmeasured factors played a greater role. Conclusion In countries undergoing epidemiological transition, effects of socioeconomic status on blood pressure may vary by gender. In women, factors other than those listed above may have substantial role in mediating the association and merit investigation. PMID:24885860
Dang, Bich N.; Westbrook, Robert A.; Black, William C.; Rodriguez-Barradas, Maria C.; Giordano, Thomas P.
2013-01-01
Introduction Analogous to the business model of customer satisfaction and retention, patient satisfaction could serve as an innovative, patient-centered focus for increasing retention in HIV care and adherence to HAART, and ultimately HIV suppression. Objective To test, through structural equation modeling (SEM), a model of HIV suppression in which patient satisfaction influences HIV suppression indirectly through retention in HIV care and adherence to HAART. Methods We conducted a cross-sectional study of adults receiving HIV care at two clinics in Texas. Patient satisfaction was based on two validated items, one adapted from the Consumer Assessment of Healthcare Providers and Systems survey (“Would you recommend this clinic to other patients with HIV?) and one adapted from the Delighted-Terrible Scale, (“Overall, how do you feel about the care you got at this clinic in the last 12 months?”). A validated, single-item question measured adherence to HAART over the past 4 weeks. Retention in HIV care was based on visit constancy in the year prior to the survey. HIV suppression was defined as plasma HIV RNA <48 copies/mL at the time of the survey. We used SEM to test hypothesized relationships. Results The analyses included 489 patients (94% of eligible patients). The patient satisfaction score had a mean of 8.5 (median 9.2) on a 0- to 10- point scale. A total of 46% reported “excellent” adherence, 76% had adequate retention, and 70% had HIV suppression. In SEM analyses, patient satisfaction with care influences retention in HIV care and adherence to HAART, which in turn serve as key determinants of HIV suppression (all p<.0001). Conclusions Patient satisfaction may have direct effects on retention in HIV care and adherence to HAART. Interventions to improve the care experience, without necessarily targeting objective clinical performance measures, could serve as an innovative method for optimizing HIV outcomes. PMID:23382948
Kapetanovic, Suad; Griner, Ray; Zeldow, Bret; Nichols, Sharon; Leister, Erin; Gelbard, Harris A.; Miller, Tracie L.; Hazra, Rohan; Mendez, Armando J.; Malee, Kathleen; Kammerer, Betsy; Williams, Paige L.
2014-01-01
Objective To examine the relationship between markers of vascular dysfunction and neurodevelopmental outcomes in perinatally HIV-infected (PHIV+) and perinatally HIV-exposed but uninfected (PHEU) youth. Design Cross-sectional design within a prospective, 15-site US-based cohort study. Methods Neurodevelopmental outcomes were evaluated in relation to nine selected vascular biomarkers in 342 youth (212 PHIV+, 130 PHEU). Serum levels were assessed for adiponectin, C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6), soluble vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-selectin), monocyte chemoattractant protein (sMCP-1), intercellular adhesion molecule-1 (sICAM-1), and P-selectin (sP-selectin). The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) was administered at entry, yielding a Full-Scale IQ score, and four index scores. Factor analysis was conducted to reduce the biomarkers to fewer factors with related biological roles. Structural equation models (SEMs) were used to measure associations between resulting factors and WISC-IV scores. Results Mean participant age was 11.4 years, 54% were female, 70% black. The nine biomarkers were clustered into three factor groups: F1 (fibrinogen, CRP, and IL-6); F2 (sICAM-1 and sVCAM-1); and F3 (MCP-1, sP-selectin, and sE-selectin). Adiponectin showed little correlation with any factor. SEMs revealed significant negative association of F1 with WISC-IV processing speed score in the total cohort. This effect remained significant after adjusting for HIV status and other potential confounders. A similar association was observed when restricted to PHIV+ participants in both unadjusted and adjusted SEMs. Conclusion Aggregate measures of fibrinogen, CRP, and IL-6 may serve as a latent biomarker associated with relatively decreased processing speed in both PHIV+ and PHEU youth. PMID:24670521
NASA Astrophysics Data System (ADS)
Lentini, N. E.; Hackett, E. E.
2015-10-01
Inadequate representation of the environment is a limitation for prediction of radar system performance as well as for validation of propagation codes. To improve understanding of how different environmental effects/parameters compete and compare, this study examines the sensitivity of radar wave propagation to a suite of environmental parameters for low grazing angle near-surface radar systems at 3-15 GHz at horizontal and vertical polarizations. A global sensitivity analysis method is used, which accounts for parameter interactions, and propagation is modeled using the parabolic equation method. Environmental parameters examined include eight sea state parameters and eight parameters characterizing the vertical structure and character of range-independent refractivity profiles. The relative importance of parameters varies more with frequency than polarization, and parameter interactions are found to be significant. Atmospheric mixed layer parameters are found to be the most sensitive, particularly the thickness of the mixed layer. The most significant ocean surface parameter is swell period, although sea directionality is important at 3 GHz and sea surface roughness and salinity are important at 9 and 15 GHz. Because of the spatial variability of sensitivity throughout the domain, regional analysis is performed to determine the most important parameters in different regions of the domain (1000 m in altitude and 60 km in range). These regional sensitivity results, along with those for the whole domain, provide guidance on prioritization of environmental characterization in numerical weather prediction and inversion studies (e.g., refractivity from clutter studies), which are two common methods currently used to address environmental effects on propagation.
Psychometric validation of the Dysexecutive Questionnaire (DEX).
Shaw, Simone; Oei, Tian P S; Sawang, Sukanlaya
2015-03-01
This study reported on the validation of the psychometric properties, the factorability, validity, and sensitivity of the Dysexecutive Questionnaire (DEX) in 3 clinical and nonclinical samples. A mixed sample of 997 participants--community (n = 663), psychiatric (depressed [n = 92] and anxious [n = 122]), and neurologically impaired (n = 120)--completed self-report questionnaires assessing executive dysfunction, depression, anxiety, stress, general self-efficacy, and satisfaction with life. Before analyses the data were randomly split into 2 subsets (A and B). Exploratory factor analysis performed on Subset A produced a 3-factor model (Factor 1: Inhibition, Factor 2: Volition, and Factor 3: Social Regulation) in which 15 of the original 20 items provided a revised factor structure that was superior to all other structures. A series of confirmatory factor analyses performed on Subset B confirmed that this revised factor structure was valid and reliable. The revised structure, labeled the DEX-R, was found to be a reliable and valid tool for assessing behavioral symptoms of dysexecutive functioning in mixed community, psychiatric, and neurological samples. PMID:25602692
NASA Astrophysics Data System (ADS)
Xiong, D. R.; Deng, L.; Zhang, C.
2015-08-01
Starting from hydrodynamic equations, we have established a set of hydrodynamic equations for average flow and a set of dynamic equations of auto- and cross-correlations of turbulent velocity and temperature fluctuations, following the classic Reynold's treatment of turbulence. The combination of the two sets of equations leads to a complete and self-consistent mathematical expressions ready for the calculations of stellar structure and oscillations. In this paper, non-locality and anisotropy of turbulent convection are concisely presented, together with defining and calibrating of the three convection parameters (c1, c2 and c3) included in the algorithm. With the non-local theory of convection, the structure of the convective envelope and the major characteristics of non-adiabatic linear oscillations are demonstrated by numerical solutions. Great effort has been exercised to the choice of convection parameters and pulsation instabilities of the models, the results of which show that within large ranges of all three parameters (c1, c2 and c3) the main properties of pulsation stability keep unchanged.
NASA Astrophysics Data System (ADS)
Reus, V.; Belloni, L.; Zemb, T.; Lutterbach, N.; Versmold, H.
1997-04-01
Electrostatically stabilized aqueous suspensions of bromopolystyrene particles have been studied by scattering and osmotic pressure measurements. We investigated their structure and the interparticle interactions as a function of the volume fraction at very low salinity of the order of micromole/l. At slow crystallization speed we observe perfect crystals, body centrered cubic crystals by light scattering for volume fractions between 0.04 and 0.7% and face centrered cubic crystals by Ultra Small Angle X ray Scattering (USAXS) for higher volume fractions (2 12%). After shear the crystal displays other structures. At low volume fractions (0.1 0.3%), some reflexions disappear by light scattering whereas a strong diffuse “prepeak" appears before the first Bragg peak for higher concentrations (2 12%) evidenced by USAXS. This “prepeak" can be attributed to defects in the crystal. Osmotic pressures have been measured by difference between the hydrostatic pressure in the solution and in the reservoir separated by an hemipermeable membrane. The experimental data are very well reproduced by the Poisson Boltzmann Cell (PBC) theory which shows that the interaction between particles is purely repulsive. No attractive contribution has been experimentally detected. By calculating the mean square displacement of a particle inside its cage from the eccentric PBC model, we have verified that the Lindemann criterion for the existence of crystals (against melting) is satisfied. This study has allowed to determine the equation of state of an electrostatical colloidal crystal and is equivalent to an ultraprecise force/distance measurement between latex particles since the measured forces are of the order of 10^{-12} N for distances of the order of 4000 Å. Des suspensions aqueuses de particules de bromopolystyrène ont été caractérisées par diffusion de lumière, diffusion de rayons X aux petits angles et par des mesures de pression osmotique. Nous avons ainsi étudié leur structure et les interactions interparticulaires en fonction de la fraction volumique à salinité constante de l'ordre de la micromole/l. Lorsque la cristallisation est lente, nous observons des cristaux parfaits cubiques centrés par diffusion de lumière pour des fractions volumiques comprises entre 0,04 et 0,7 % et cubiques faces centrées pax diffusion de rayons X aux petits angles pour des fractions volumiques plus élevées (2 12 %). Après cisaillement, des défauts apparaissent dans les cristaux ; ils sont caractérisés par la disparition de certaines raies de Bragg en diffusion de lumière pour des échantillons de fraction volumique comprise entre 0,1 et 0,3 % et par la présence d'un pré pic observé par diffusion de rayons X aux petits angles avant le premier pic de Bragg, pour des échantillons plus concentrés (2 12 %). Les pressions osmotiques ont été mesurées par différence de pression hydrostatique entre la solution et le réservoir séparés par une membrane hémiperméable. Les données expérimentales sont bien reproduites par la théorie Poisson Boltzmann Réseau (PBR) qui montre que les interactions sont purement répulsives. Aucune force attractive faible de longue portée n'a été détectée expérimentalement. En calculant le déplacement moyen d'une particule à l'intérieur de sa cage à l'aide du modèle PBR "excentré", nous avons vérifié que le critère de Lindemann était satisfait pour tous les cristaux observés. Cette étude a permis de déterminer l'équation d'état d'un cristal colloidal électrostatique. Les résultats sont équivalents à une mesure de force ultraprécise puisque les forces d'interaction mesurées entre particules sont de l'ordre de 10^{-12} N pour des distances centre à centre de l'ordre de 4000 Å.
N. Nettelmann; B. Holst; A. Kietzmann; M. French; R. Redmer; D. Blaschke
2008-06-06
The equation of state of hydrogen, helium, and water effects interior structure models of giant planets significantly. We present a new equation of state data table, LM-REOS, generated by large scale quantum molecular dynamics simulations for hydrogen, helium, and water in the warm dense matter regime, i.e.for megabar pressures and temperatures of several thousand Kelvin, and by advanced chemical methods in the complementary regions. The influence of LM-REOS on the structure of Jupiter is investigated and compared with state-of-the-art results within a standard three-layer model consistent with astrophysical observations of Jupiter. Our new Jupiter models predict an important impact of mixing effects of helium in hydrogen with respect to an altered compressibility and immiscibility.
Narcotics Center Questionnaire (Spring 1969).
ERIC Educational Resources Information Center
Marks, John B.; And Others
This questionnaire assesses drug knowledge, drug use practices, and attitudes in junior high school, senior high school, and college students. The 115 items (multiple choice, yes/no, agree/disagree, or completion) deal with personal and demographic data, general attitudes, attitudes toward institutions (police, American business, Army, etc.),…
Physical Activity Questionnaire Search Results
Neighborhood Physical Activity Questionnaire (NPAQ) A1 In a USUAL WEEK, do you cycle in or around your new neighbourhood or new local area to get to or from somewhere (such as cycling to a shop or to public transport) or for recreation, health or fitness (including cycling with your dog)?
College Student Services Accreditation Questionnaire.
ERIC Educational Resources Information Center
Cassel, Russell N.
1979-01-01
This questionnaire is intended for use as one aspect in accrediting the "Student Personnel Services" which an institution of higher learning provides for students. Areas in question include personal development, health fostering, vocational preparation, effective personalized learning, economic viability, transpersonal offerings, and satisfactory…
HEALTH AND HAZARD ASSESSMENT QUESTIONNAIRE
Fleming, Andrew J.
Questionnaire, the Director, University Health Services will assess the applicant's capability to perform that it is used to determine whether the prospective employee has the physical, and other capabilities, to perform accommodation is required to enable an employee to carry out the inherent requirements of the job. For more
Physical Activity Questionnaire Search Results
The Physical Activity Questionnaire for Elderly Japanese (PAQ-EJ) 1 Over 7 typical days, how often did you take a walk or ride a bicycle on errands such as going to or from a store or taking children to school?
Diet History Questionnaire: Canadian Version
The Diet History Questionnaire (DHQ) and the DHQ nutrient database were modified for use in Canada through the collaborative efforts of Dr. Amy Subar and staff at the Risk Factor Monitoring and Methods Branch, and Dr. Ilona Csizmadi and colleagues in the Division of Population Health and Information at the Alberta Cancer Board in Canada.
HEALTH AND HAZARD ASSESSMENT QUESTIONNAIRE
Fleming, Andrew J.
1 HEALTH AND HAZARD ASSESSMENT QUESTIONNAIRE The information on this form will be kept strictly the property of the University Health Service of the University of Newcastle. The University of Newcastle is committed to achieving a safe and healthy workplace for its staff. Based on the completed Health and Hazard
Physical Activity Questionnaire Search Results
Global Physical Activity Questionnaire (GPAQ) 13 Do you do any moderate-intensity sports, fitness or recreational (leisure) activities that causes a small increase in breathing or heart rate such as brisk walking, cycling, swimming, volleyball) for at least 10 minutes continuously?
Development and validity of the Outdoor Falls Questionnaire.
Chippendale, Tracy
2015-09-01
The aim of this study was to develop and examine the content and face validity of the Outdoor Falls Questionnaire. The initial questionnaire was developed by the primary investigator on the basis of the existing literature on outdoor falls. A rating scale was used to obtain feedback from content experts to ascertain the validity of each question and the questionnaire as a whole. Cognitive interviewing of community-dwelling seniors was performed to ensure accurate interpretation of each question. An expert in questionnaire design reviewed the questions for language and structure. Content experts rated the questionnaire as a whole as 'quite relevant' or 'very relevant' to outdoor falls. The majority of individual questions (22 of 32) were rated by experts as either quite relevant or very relevant. Feedback from reviewers and older adults on specific questions were incorporated into the revised questionnaire. Preliminary testing demonstrates that the Outdoor Falls Questionnaire has good content and face validity. Further testing is needed to examine factor structure, to establish reliability, internal consistency, and interclass correlations. PMID:25851838
Swope, Sarah M; Parker, Ingrid M
2012-12-01
Herbivores, seed predators, and pollinators can exert strong impacts on their host plants. They can also affect the strength of each other's impact by modifying traits in their shared host, producing super- or sub-additive outcomes. This phenomenon is especially relevant to biological control of invasive plants because most invaders are attacked by multiple agents. Unfortunately, complex interactions among agents are rarely studied. We used structural equation modeling (SEM) to quantify the effect of two biocontrol agents and generalist pollinators on the invasive weed Centaurea solstitialis, and to identify and quantify the direct and indirect interaction pathways among them. The weevil Eustenopus villosus is both a bud herbivore and a predispersal seed predator; the fly Chaetorellia succinea is also a predispersal seed predator; Apis mellifera is the primary pollinator. We conducted this work at three sites spanning the longitudinal range of C. solstitialis in California (USA) from the coast to the Sierra Nevada Mountains. SEM revealed that bud herbivory had the largest total effect on the weed's fecundity. The direct effect of bud herbivory on final seed set was 2-4 times larger in magnitude than the direct effect of seed predation by both agents combined. SEM also revealed important indirect interactions; by reducing the number of inflorescences plants produced, bud herbivory indirectly reduced the plant's attractiveness to ovipositing seed predators. This indirect, positive pathway reduced bud herbivory's direct negative effect by 11-25%. In the same way, bud herbivory also reduced pollinator visitation, although the magnitude of this pathway was relatively small. E. villosus oviposition deterred C. succinea oviposition, which is unfortunate because C. succinea is the more voracious of the seed predators. Finally, C. succinea oviposition indirectly deterred pollinator visitation, thereby enhancing its net effect on the plant. This study demonstrates the powerful insights that can be gained from the SEM approach in understanding the multiple direct and indirect interactions among agents and pollinators and their effects on an invasive weed. Such an approach may improve our ability to manage weeds with biocontrol agents by identifying pathways that could be exploited by future agents and minimizing the possibility of interference with established agents. PMID:23387114
NASA Astrophysics Data System (ADS)
Katul, Gabriel G.; Manes, Costantino; Porporato, Amilcare; Bou-Zeid, Elie; Chamecki, Marcelo
2015-09-01
The compensated three-dimensional turbulent kinetic energy spectrum exhibits a peculiar bump at wave numbers in the vicinity of the crossover from inertial to viscous regimes due to pile up in turbulent kinetic energy, a phenomenon referred to as the bottleneck effect. The origin of this bump is linked to an inflection point in the second-order structure function in physical space caused by competition between vortex stretching and viscous diffusion mechanisms. The bump location and magnitude are reasonably predicted from a novel analytical solution to the Von Kármán-Howarth equation reflecting the competition between these two mechanisms and accounting for variable structure skewness with decreasing scale.
Katul, Gabriel G; Manes, Costantino; Porporato, Amilcare; Bou-Zeid, Elie; Chamecki, Marcelo
2015-09-01
The compensated three-dimensional turbulent kinetic energy spectrum exhibits a peculiar bump at wave numbers in the vicinity of the crossover from inertial to viscous regimes due to pile up in turbulent kinetic energy, a phenomenon referred to as the bottleneck effect. The origin of this bump is linked to an inflection point in the second-order structure function in physical space caused by competition between vortex stretching and viscous diffusion mechanisms. The bump location and magnitude are reasonably predicted from a novel analytical solution to the Von Kármán-Howarth equation reflecting the competition between these two mechanisms and accounting for variable structure skewness with decreasing scale. PMID:26465558
NASA Technical Reports Server (NTRS)
Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)
1994-01-01
In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.
High-Accuracy Finite Difference Equations for Simulation of Photonic Structures
Hadley, G.R.
1999-04-23
Progress towards the development of such algorithms as been reported for waveguide analysis'-3and vertical-cavity laser simulation. In all these cases, the higher accuracy order was obtained for a single spatial dimension. More recently, this concept was extended to differencing of the Helmholtz Equation on a 2-D grid, with uniform regions treated to 4th order and dielectric interfaces to 3'd order5. No attempt was made to treat corners properly. In this talk I will describe the extension of this concept to allow differencing of the Helmholtz Equation on a 2-D grid to 6* order in uniform regions and 5* order at dielectric interfaces. In addition, the first known derivation of a finite difference equation for a dielectric comer that allows correct satisfaction of all boundary conditions will be presented. This equation is only accurate to first order, but as will be shown, results in simulations that are third-order-accurate. In contrast to a previous approach3 that utilized a generalized Douglas scheme to increase the accuracy order of the difference second derivative, the present method invokes the Helmholtz Equation itself to convert derivatives of high order in a single direction into mixed
The higher grading structure of the WKI hierarchy and the two-component short pulse equation
NASA Astrophysics Data System (ADS)
França, G. S.; Gomes, J. F.; Zimerman, A. H.
2012-08-01
A higher grading affine algebraic construction of integrable hierarchies, containing the Wadati-Konno-Ichikawa (WKI) hierarchy as a particular case, is proposed. We show that a two-component generalization of the Schäfer-Wayne short pulse equation arises quite naturally from the first negative flow of the WKI hierarchy. Some novel integrable nonautonomous models are also proposed. The conserved charges, both local and nonlocal, are obtained from the Riccati form of the spectral problem. The loop-soliton solutions of the WKI hierarchy are systematically constructed through gauge followed by reciprocal Bäcklund transformation, establishing the precise connection between the whole WKI and AKNS hierarchies. The connection between the short pulse equation with the sine-Gordon model is extended to a correspondence between the two-component short pulse equation and the Lund-Regge model.
Briki, Walid; Chaouachi, Anis; Patrick, Thomas; Chamari, Karim
2015-01-01
Aim The present study attempted to test McCullough and Willoughby’s hypothesis that self-control mediates the relationships between religiosity and psychosocial outcomes. Specifically, this study examined whether trait self-control (TSC) mediates the relationship of identified-introjected religiosity with positive and negative health-related-feelings (HRF) in healthy Muslims. Methods Two hundred eleven French-speaking participants (116 females, 95 males; Mage = 28.15, SDage = 6.90) answered questionnaires. One hundred ninety participants were retained for the analyses because they reported to be healthy (105 females, 85 males; Mage = 27.72, SDage = 6.80). To examine the relationships between religiosity, TSC and HRF, two competing mediation models were tested using structural equation model analysis: While a starting model used TSC as mediator of the religiosity-HRF relationship, an alternative model used religiosity as mediator of the TSC-HRF relationship. Results The findings revealed that TSC mediated the relationship between identified religiosity and positive HRF, and that identified religiosity mediated the relationship between TSC and positive and negative HRF, thereby validating both models. Moreover, the comparison of both models showed that the starting model explained 13.211% of the variance (goodness of fit = 1.000), whereas the alternative model explained 6.877% of the variance (goodness of fit = 0.987). Conclusion These results show that the starting model is the most effective model to account for the relationships between religiosity, TSC, and HRF. Therefore, this study provides initial insights into how religiosity influences psychological health through TSC. Important practical implications for the religious education are suggested. PMID:25962179
Yuki, Kenya; Asaoka, Ryo; Tsubota, Kazuo
2015-01-01
Purpose To investigate the relationship between visual function and the risks of falling and injurious falls in subjects with primary open angle glaucoma (POAG) Methods Questionnaires were conducted in 365 POAG patients to assess history of falls and falls with injury and general patient health. Structural equation modeling (SEM) was used to investigate the relationship between visual function, as measured by a patient’s binocular integrated visual field and visual acuity (VA), general health and the risks of falling and injurious falls. Results Among the 365 subjects, 55 subjects experienced falls in the past year. A significant difference was observed in worse-eye VA between the faller and non-faller groups (p = 0.03). SEM of fallers obtained a Root Mean Square Error of Approximation (RMSEA) of 0.035 and a Comparative Fit Index (CFI) of 0.99. The 95% confidence intervals (CI) of regression coefficients from this model suggested better VA and worse VA were significant risk factors for falling. Among the 55 fallers, 22 subjects experienced an associated injury. There was a significant difference in gender between the non-injurious and injurious faller groups (p = 0.002). SEM of injurious fallers obtained a RMSEA of 0.074 and a CFI of 0.97. In this SEM model, the 95% CI of regression coefficients suggested gender and average total deviation values in the lower peripheral visual field were significant risk factors for an injurious fall. Conclusions This study suggests that worse-eye and better-eye VAs are associated with falls. Furthermore, patients with inferior visual field loss and females were found to be at greater risk of injurious falls. PMID:26053502
LNG FEM: GENERATING GRADED MESHES AND SOLVING ELLIPTIC EQUATIONS ON 2-D DOMAINS OF POLYGONAL, Minnesota 55455Â0436 Phone: 612-624-6066 Fax: 612-626-7370 URL: http://www.ima.umn.edu #12;LNG FEM AND VICTOR NISTOR Abstract. We develop LNG FEM, a software package for graded mesh gen- eration
The solution of linear systems of equations with a structural analysis code on the NAS CRAY-2
NASA Technical Reports Server (NTRS)
Poole, Eugene L.; Overman, Andrea L.
1988-01-01
Two methods for solving linear systems of equations on the NAS Cray-2 are described. One is a direct method; the other is an iterative method. Both methods exploit the architecture of the Cray-2, particularly the vectorization, and are aimed at structural analysis applications. To demonstrate and evaluate the methods, they were installed in a finite element structural analysis code denoted the Computational Structural Mechanics (CSM) Testbed. A description of the techniques used to integrate the two solvers into the Testbed is given. Storage schemes, memory requirements, operation counts, and reformatting procedures are discussed. Finally, results from the new methods are compared with results from the initial Testbed sparse Choleski equation solver for three structural analysis problems. The new direct solvers described achieve the highest computational rates of the methods compared. The new iterative methods are not able to achieve as high computation rates as the vectorized direct solvers but are best for well conditioned problems which require fewer iterations to converge to the solution.
Barrett, Frederick S; Johnson, Matthew W; Griffiths, Roland R
2015-11-01
The 30-item revised Mystical Experience Questionnaire (MEQ30) was previously developed within an online survey of mystical-type experiences occasioned by psilocybin-containing mushrooms. The rated experiences occurred on average eight years before completion of the questionnaire. The current paper validates the MEQ30 using data from experimental studies with controlled doses of psilocybin. Data were pooled and analyzed from five laboratory experiments in which participants (n=184) received a moderate to high oral dose of psilocybin (at least 20 mg/70 kg). Results of confirmatory factor analysis demonstrate the reliability and internal validity of the MEQ30. Structural equation models demonstrate the external and convergent validity of the MEQ30 by showing that latent variable scores on the MEQ30 positively predict persisting change in attitudes, behavior, and well-being attributed to experiences with psilocybin while controlling for the contribution of the participant-rated intensity of drug effects. These findings support the use of the MEQ30 as an efficient measure of individual mystical experiences. A method to score a "complete mystical experience" that was used in previous versions of the mystical experience questionnaire is validated in the MEQ30, and a stand-alone version of the MEQ30 is provided for use in future research. PMID:26442957
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; MacMurdy, Dale E.; Kapania, Rakesh K.
1994-01-01
Strong interactions between flow about an aircraft wing and the wing structure can result in aeroelastic phenomena which significantly impact aircraft performance. Time-accurate methods for solving the unsteady Navier-Stokes equations have matured to the point where reliable results can be obtained with reasonable computational costs for complex non-linear flows with shock waves, vortices and separations. The ability to combine such a flow solver with a general finite element structural model is key to an aeroelastic analysis in these flows. Earlier work involved time-accurate integration of modal structural models based on plate elements. A finite element model was developed to handle three-dimensional wing boxes, and incorporated into the flow solver without the need for modal analysis. Static condensation is performed on the structural model to reduce the structural degrees of freedom for the aeroelastic analysis. Direct incorporation of the finite element wing-box structural model with the flow solver requires finding adequate methods for transferring aerodynamic pressures to the structural grid and returning deflections to the aerodynamic grid. Several schemes were explored for handling the grid-to-grid transfer of information. The complex, built-up nature of the wing-box complicated this transfer. Aeroelastic calculations for a sample wing in transonic flow comparing various simple transfer schemes are presented and discussed.
White, R D; Robson, R E
2011-09-01
In this paper, we generalize the semiclassical Boltzmann kinetic equation for dilute gases to consider highly nonequilibrium electrons and positrons in soft condensed matter, accounting rigorously for all types of interactions, including positronium formation, and allowing for both coherent and incoherent scattering processes. The limitations inherent in the seminal paper of Cohen and Lekner [M. H. Cohen and J. Lekner, Phys. Rev. 158, 305 (1967); Y. Sakai, J. Phys. D 40, R441 (2007)] are avoided by solving the kinetic equation using a "multiterm" spherical harmonic representation of the velocity distribution function, as well as formulating a necessarily nonperturbative treatment of nonconservative collisional processes such as positronium formation. Numerical calculations of transport properties are carried out for a Percus-Yevick model of a hard-sphere system, and for positrons in liquid argon. New phenomena are predicted, including structure-induced negative conductivity and anisotropic diffusion. PMID:22060346
Waldyr A. Rodrigues Jr.; Samuel A. Wainer
2015-09-24
We discuss the physics of interacting tensor fields and particles living in $M=\\mathrm{S0}(1,4)/\\mathrm{S0} (1,3)\\simeq\\mathbb{R}\\times S^{3}$ a submanifold of $\\mathring{M}=(\\mathbb{R}^{5},\\boldsymbol{\\mathring{g}})$, where $\\boldsymbol{\\mathring {g}}$ has signature $(1,4)$. Structure $(M,\\boldsymbol{g})$ where $(\\boldsymbol{g=i}^{\\ast}\\boldsymbol{\\mathring{g}})$ is a Lorentzian manifold. Structure $(M,\\boldsymbol{g,}\\tau_{\\boldsymbol{g}},\\uparrow)$ is primely used to study the energy-momentum conservation law (for a system of physical fields (and particles) living in $M$ and to get the respective equations of motion. We construct two different de Sitter spacetime structures $M^{dSL}=(M,\\boldsymbol{g,D},\\tau_{\\boldsymbol{g}},\\uparrow)$ and $M^{dSTP}=(M,\\boldsymbol{g,\
Microscopic Theory of the Nuclear Equation of State and Neutron Star Structure
NASA Astrophysics Data System (ADS)
Baldo, Marcello; Burgio, Fiorella
The Bethe-Brueckner-Goldstone many-body theory of the Nuclear Equation of State is reviewed in some details. In the theory, one performs an expansion in terms of the Brueckner two-body scattering matrix and an ordering of the corresponding many-body diagrams according to the number of their hole-lines. Recent results are reported, both for symmetric and for pure neutron matter, based on realistic two-nucleon interactions. It is shown that there is strong evidence of convergence in the expansion. Once three-body forces are introduced, the phenomenological saturation point is reproduced and the theory is applied to the study of neutron star properties. One finds that in the interior of neutron stars the onset of hyperons strongly softens the Nuclear Equation of State. As a consequence, the maximum mass of neutron stars turns out to be at the lower limit of the present phenomenological observation.
The Hamiltonian structure of Dirac's equation in tensor form and its Fermi quantization
NASA Technical Reports Server (NTRS)
Reifler, Frank; Morris, Randall
1992-01-01
Currently, there is some interest in studying the tensor forms of the Dirac equation to elucidate the possibility of the constrained tensor fields admitting Fermi quantization. We demonstrate that the bispinor and tensor Hamiltonian systems have equivalent Fermi quantizations. Although the tensor Hamiltonian system is noncanonical, representing the tensor Poisson brackets as commutators for the Heisenberg operators directly leads to Fermi quantization without the use of bispinors.
Design of psychosocial factors questionnaires: a systematic measurement approach
Vargas, Angélica; Felknor, Sarah A
2012-01-01
Background Evaluation of psychosocial factors requires instruments that measure dynamic complexities. This study explains the design of a set of questionnaires to evaluate work and non-work psychosocial risk factors for stress-related illnesses. Methods The measurement model was based on a review of literature. Content validity was performed by experts and cognitive interviews. Pilot testing was carried out with a convenience sample of 132 workers. Cronbach’s alpha evaluated internal consistency and concurrent validity was estimated by Spearman correlation coefficients. Results Three questionnaires were constructed to evaluate exposure to work and non-work risk factors. Content validity improved the questionnaires coherence with the measurement model. Internal consistency was adequate (?=0.85–0.95). Concurrent validity resulted in moderate correlations of psychosocial factors with stress symptoms. Conclusions Questionnaires´ content reflected a wide spectrum of psychosocial factors sources. Cognitive interviews improved understanding of questions and dimensions. The structure of the measurement model was confirmed. PMID:22628068
Byrd, Jimmy
2010-01-14
The purpose of the study was to examine multilevel regression models in the context of multilevel structural equation modeling (SEM) in terms of accuracy of parameter estimates, standard errors, and fit indices in normal ...
Franz, Delbert D.; Melching, Charles S.
1997-01-01
The Full EQuations UTiLities (FEQUTL) model is a computer program for computation of tables that list the hydraulic characteristics of open channels and control structures as a function of upstream and downstream depths; these tables facilitate the simulation of unsteady flow in a stream system with the Full Equations (FEQ) model. Simulation of unsteady flow requires many iterations for each time period computed. Thus, computation of hydraulic characteristics during the simulations is impractical, and preparation of function tables and application of table look-up procedures facilitates simulation of unsteady flow. Three general types of function tables are computed: one-dimensional tables that relate hydraulic characteristics to upstream flow depth, two-dimensional tables that relate flow through control structures to upstream and downstream flow depth, and three-dimensional tables that relate flow through gated structures to upstream and downstream flow depth and gate setting. For open-channel reaches, six types of one-dimensional function tables contain different combinations of the top width of flow, area, first moment of area with respect to the water surface, conveyance, flux coefficients, and correction coefficients for channel curvilinearity. For hydraulic control structures, one type of one-dimensional function table contains relations between flow and upstream depth, and two types of two-dimensional function tables contain relations among flow and upstream and downstream flow depths. For hydraulic control structures with gates, a three-dimensional function table lists the system of two-dimensional tables that contain the relations among flow and upstream and downstream flow depths that correspond to different gate openings. Hydraulic control structures for which function tables containing flow relations are prepared in FEQUTL include expansions, contractions, bridges, culverts, embankments, weirs, closed conduits (circular, rectangular, and pipe-arch shapes), dam failures, floodways, and underflow gates (sluice and tainter gates). The theory for computation of the hydraulic characteristics is presented for open channels and for each hydraulic control structure. For the hydraulic control structures, the theory is developed from the results of experimental tests of flow through the structure for different upstream and downstream flow depths. These tests were done to describe flow hydraulics for a single, steady-flow design condition and, thus, do not provide complete information on flow transitions (for example, between free- and submerged-weir flow) that may result in simulation of unsteady flow. Therefore, new procedures are developed to approximate the hydraulics of flow transitions for culverts, embankments, weirs, and underflow gates.
NASA Astrophysics Data System (ADS)
Bilonick, Richard A.; Connell, Daniel P.; Talbott, Evelyn O.; Rager, Judith R.; Xue, Tao
2015-02-01
The objective of this study was to remove systematic bias among fine particulate matter (PM2.5) mass concentration measurements made by different types of samplers used in the Pittsburgh Aerosol Research and Inhalation Epidemiology Study (PARIES). PARIES is a retrospective epidemiology study that aims to provide a comprehensive analysis of the associations between air quality and human health effects in the Pittsburgh, Pennsylvania, region from 1999 to 2008. Calibration was needed in order to minimize the amount of systematic error in PM2.5 exposure estimation as a result of including data from 97 different PM2.5 samplers at 47 monitoring sites. Ordinary regression often has been used for calibrating air quality measurements from pairs of measurement devices; however, this is only appropriate when one of the two devices (the "independent" variable) is free from random error, which is rarely the case. A group of methods known as "errors-in-variables" (e.g., Deming regression, reduced major axis regression) has been developed to handle calibration between two devices when both are subject to random error, but these methods require information on the relative sizes of the random errors for each device, which typically cannot be obtained from the observed data. When data from more than two devices (or repeats of the same device) are available, the additional information is not used to inform the calibration. A more general approach that often has been overlooked is the use of a measurement error structural equation model (SEM) that allows the simultaneous comparison of three or more devices (or repeats). The theoretical underpinnings of all of these approaches to calibration are described, and the pros and cons of each are discussed. In particular, it is shown that both ordinary regression (when used for calibration) and Deming regression are particular examples of SEMs but with substantial deficiencies. To illustrate the use of SEMs, the 7865 daily average PM2.5 mass concentration measurements made by seven collocated samplers at an urban monitoring site in Pittsburgh, Pennsylvania, were used. These samplers, which included three federal reference method (FRM) samplers, three speciation samplers, and a tapered element oscillating microbalance (TEOM), operated at various times during the 10-year PARIES study period. Because TEOM measurements are known to depend on temperature, the constructed SEM provided calibration equations relating the TEOM to the FRM and speciation samplers as a function of ambient temperature. It was shown that TEOM imprecision and TEOM bias (relative to the FRM) both decreased as temperature increased. It also was shown that the temperature dependency for bias was non-linear and followed a sigmoidal (logistic) pattern. The speciation samplers exhibited only small bias relative to the FRM samplers, although the FRM samplers were shown to be substantially more precise than both the TEOM and the speciation samplers. Comparison of the SEM results to pairwise simple linear regression results showed that the regression results can differ substantially from the correctly-derived calibration equations, especially if the less-precise device is used as the independent variable in the regression.
On the Equation H=mv^2 and the Fine Structure of the Hydrogen Atom
Ezzat G. Bakhoum
2002-12-26
The recently introduced reconciliation of the theories of special relativity and wave mechanics implies that the mass-energy equivalence principle must be expressed mathematically as H = mv^2, where H is the total energy of a particle, m is its relativistic mass, and v is its velocity; not H = mc^2 as was widely believed. In this paper, the equation H = mv^2 will be used to calculate the energy levels in the spectrum of the hydrogen atom. It is demonstrated that the well-known Sommerfeld-Dirac formula is still obtained, but without the constant term m_0 c^2 that was originally present in the formula.
NASA Astrophysics Data System (ADS)
Ravindran, P.; Asokamani, R.
1994-07-01
We report here the ambient and high-pressure electronic-structure calculations of the potentially important ordered intermetallic alloy Zr3Al obtained using the self-consistent linear muffin-tin orbitals (LMTO) method. Further total-energy calculations were made using the tight-binding LMTO scheme in the L12 and DO19 phases in order to study its structural stability. From total-energy studies and the band filling of bonding states results, we conclude that it is easier to create instability in the L12 lattice of Zr3Al and this prediction is consistent with the experimentally observed martensitic structural transition from DO19-->L12 structure. To make a comparative study, the band structure and total-energy calculations of isoelectronic Ti3Al were also made. The calculated bulk modulus and its pressure derivative, determined using a universal equation of state, are reported. The nature of chemical bonding in Zr3Al is also discussed. Using the band-structure results, within the BCS formalism, the superconducting transition temperature (Tc) was calculated and it is compared with the experimental value. The ambient-pressure band-structure, and Tc calculations of the A15 compound Nb3Al were made with a view to compare its superconducting behavior with that of Zr3Al at high pressures as Zr3Al should mimic Nb3Al at high pressures. The pressure dependence of Tc of Zr3Al is analyzed. Our calculations on Zr3Al are in contradiction with the often quoted correlation between the low density of states at the Fermi level and structural stability in similar systems and this is further corroborated with our more recent studies on Ti3In and Ni3In.
19 CFR 357.105 - Questionnaires.
Code of Federal Regulations, 2010 CFR
2010-04-01
...ADMINISTRATION, DEPARTMENT OF COMMERCE SHORT SUPPLY PROCEDURES § 357.105 Questionnaires...product to determine whether it is in short supply. Questionnaires shall be completed...not received within this period will be deemed favorable to the...
NASA Astrophysics Data System (ADS)
Bao, Minhang; Yang, Heng; Sun, Yuancheng; French, Paddy J.
2003-11-01
We modified the Reynolds equation to extend its applications to squeeze-film air damping of perforated plates (i.e., the hole-plates) by adding a term related to the damping effect of gas flow through holes. The modified Reynolds equation (MRE) is generally effective for a perforated hole-plate with a finite thickness and finite lateral dimensions as well as a non-perforated hole-plate. Analytical expressions of damping pressure for long rectangular hole-plates and regular rectangular hole-plates have been found. For MEMS devices with typical dimensions, 'effective damping width' approximation is introduced so that the boundary effect on damping force can be treated easily. The conditions for 'effective damping width' approximation are discussed. Based on the concept of 'effective damping width', damping forces for circular plates and even hole-plates with irregular shapes can be found. The results obtained by the MRE method match the numerical results obtained by ANSYS/FLOTRAN very well. The comparison between the MRE results and the experimental results by Kim et al (1999 MEMS '99 pp 296-301) shows that the MRE results agree with the experimental results much better than the FEM simulation given by Kim et al.
Kimura, Daisuke; Nakatani, Ken; Takeda, Tokunori; Fujita, Takashi; Sunahara, Nobuyuki; Inoue, Katsumi; Notoya, Masako
2015-01-01
The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated “Social participation” acted on cognitive function. PMID:25658829
Hamilton, J.D. ); O'Flaherty, E.J.; Shukla, R.; Gartside, P.S. ); Ross, R. )
1994-01-01
This study provided an assessment of the effects of lead on early growth in rats based on structural equation modeling and nested analysis of variance (ANOVA). Structural equation modeling showed that lead in drinking water (250, 500, or 1000 ppm) had a direct negative effect on body weight and tail length (i.e., growth) in female rats during the first week of exposure. During the following 2 weeks of exposure, high correlation between growth measurements taken over time resulted in reduced early postnatal growth. By the fourth week of exposure, reduced growth was not evident. Mating began after 8 weeks of exposure, and exposure continued during gestation. Decreased fetal body weight was detected when the effects of litter size, intrauterine position, and sex were controlled in a nested ANOVA. Lead exposure did not appear to affect fetal skeletal development, possibly because lead did not alter maternal serum calcium and phosphorus levels. The effect of lead on individual fetal body weight suggests that additional studies are needed to examine the effect of maternal lead exposure on fetal development and early postnatal growth. 24 refs., 4 figs., 6 tabs.
19 CFR 357.105 - Questionnaires.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 19 Customs Duties 3 2012-04-01 2012-04-01 false Questionnaires. 357.105 Section 357.105 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE SHORT SUPPLY PROCEDURES § 357.105 Questionnaires. For reviews conducted under section 106(b)(2), the Secretary normally will send questionnaires...
19 CFR 357.105 - Questionnaires.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 19 Customs Duties 3 2010-04-01 2010-04-01 false Questionnaires. 357.105 Section 357.105 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE SHORT SUPPLY PROCEDURES § 357.105 Questionnaires. For reviews conducted under section 106(b)(2), the Secretary normally will send questionnaires...
19 CFR 357.105 - Questionnaires.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 19 Customs Duties 3 2011-04-01 2011-04-01 false Questionnaires. 357.105 Section 357.105 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE SHORT SUPPLY PROCEDURES § 357.105 Questionnaires. For reviews conducted under section 106(b)(2), the Secretary normally will send questionnaires...
Senior High School Questionnaire. Appendix C.
ERIC Educational Resources Information Center
Welch, Wayne W.; And Others
This was developed in collaboration with the White Bear Lake Senior High School Evaluation Committee to evaluate the school's flexible module scheduling program. It includes a questionnaire about the school and its program and a questionnaire form for interviews in the community. Part I of the high school questionnaire has 25 questions about the…
Variable-complexity aerodynamic optimization of an HSCT wing using structural wing-weight equations
NASA Technical Reports Server (NTRS)
Hutchison, M. G.; Unger, E. R.; Mason, W. H.; Grossman, B.; Haftka, R. T.
1992-01-01
A new approach for combining conceptual and preliminary design techniques for wing optimization is presented for the high-speed civil transport (HSCT). A wing-shape parametrization procedure is developed which allows the linking of planform and airfoil design variables. Variable-complexity design strategies are used to combine conceptual and preliminary-design approaches, both to preserve interdisciplinary design influences and to reduce computational expense. In the study, conceptual-design-level algebraic equations are used to estimate aircraft weight, supersonic wave drag, friction drag and drag due to lift. The drag due to lift and wave drag are also evaluated using more detailed, preliminary-design-level techniques. The methodology is applied to the minimization of the gross weight of an HSCT that flies at Mach 3.0 with a range of 6500 miles.
Validation of a Parent Report Questionnaire
Trabulsi, Jillian; Yao, Manjiang; Bevans, Katherine B.; DeRusso, Patricia A.
2015-01-01
Objective. To evaluate the reliability and validity of the Infant Gastrointestinal Symptom Questionnaire (IGSQ), a tool to assess feeding tolerance in infants. Methods. Qualitative methods were used to develop IGSQ content across 5 symptom clusters, yielding a 13-item index of parent-reported infant digestion and elimination behaviors over the prior 7 days. Classical psychometric methods evaluated factor structure, interrater and retest reliability, and validity in 4 prospective studies of 836 infants. Results. Interrater and retest reliability were acceptable to good. IGSQ Index score was highly correlated (r = 0.89) with daily parent reports. IGSQ scores were significantly different between infants whose parents planned to switch formulas because of perceived feeding problems and those without parental concerns. Conclusions. The IGSQ is a practical, reliable, and valid method for assessment of infant gastrointestinal-related behaviors. Its use in clinical studies can provide empirical evidence to advance parent education regarding both normal and clinically meaningful feeding-related behaviors. PMID:25758425
ERIC Educational Resources Information Center
Lay, Jinn-Guey; Chi, Yu-Lin; Hsieh, Yeu-Sheng; Chen, Yu-Wen
2013-01-01
Understanding the usage of the geographic information system (GIS) among geography teachers is a crucial step in evaluating the current dissemination of GIS knowledge and skills in Taiwan's educational system. The primary contribution of this research is to further our understanding of the factors that affect teachers' GIS usage. The structural…
ERIC Educational Resources Information Center
Sebastianelli, Rose; Swift, Caroline; Tamimi, Nabil
2015-01-01
The authors examined how six factors related to content and interaction affect students' perceptions of learning, satisfaction, and quality in online master of business administration (MBA) courses. They developed three scale items to measure each factor. Using survey data from MBA students at a private university, the authors estimated structural…
A Comparison of Normal and Elliptical Estimation Methods in Structural Equation Models.
ERIC Educational Resources Information Center
Schumacker, Randall E.; Cheevatanarak, Suchittra
Monte Carlo simulation compared chi-square statistics, parameter estimates, and root mean square error of approximation values using normal and elliptical estimation methods. Three research conditions were imposed on the simulated data: sample size, population contamination percent, and kurtosis. A Bentler-Weeks structural model established the…
Structural Equation Analysis of a Hypothesised Symptom Model in the Autism Spectrum
ERIC Educational Resources Information Center
van Lang, Natasja D. J.; Boomsma, Anne; Sytema, Sjoerd; de Bildt, Annelies A.; Kraijer, Dirk W.; Ketelaars, Cees; Minderaa, Ruud B.
2006-01-01
Background: Several studies showed a different symptom structure underlying the spectrum of autistic-like disorders from the behaviour triad as mentioned in the DSM-IV. In the present study, a hypothesised symptom model for autism was constructed, based on earlier explorative findings, and was put to a confirmatory test. Method: Items from the…
ERIC Educational Resources Information Center
Stapleton, Laura M.
2008-01-01
This article discusses replication sampling variance estimation techniques that are often applied in analyses using data from complex sampling designs: jackknife repeated replication, balanced repeated replication, and bootstrapping. These techniques are used with traditional analyses such as regression, but are currently not used with structural…
Nooijen, Marcel; Huntington, Lee M.; Demel, Ond?ej; Datta, Dipayan; Kong, Liguo; Shamasundar, K. R.; Lotrich, V.; Neese, Frank
2014-02-28
The novel multireference equation-of-motion coupled-cluster (MREOM-CC) approaches provide versatile and accurate access to a large number of electronic states. The methods proceed by a sequence of many-body similarity transformations and a subsequent diagonalization of the transformed Hamiltonian over a compact subspace. The transformed Hamiltonian is a connected entity and preserves spin- and spatial symmetry properties of the original Hamiltonian, but is no longer Hermitean. The final diagonalization spaces are defined in terms of a complete active space (CAS) and limited excitations (1h, 1p, 2h, …) out of the CAS. The methods are invariant to rotations of orbitals within their respective subspaces (inactive, active, external). Applications to first row transition metal atoms (Cr, Mn, and Fe) are presented yielding results for up to 524 electronic states (for Cr) with an rms error compared to experiment of about 0.05 eV. The accuracy of the MREOM family of methods is closely related to its favorable extensivity properties as illustrated by calculations on the O{sub 2}–O{sub 2} dimer. The computational costs of the transformation steps in MREOM are comparable to those of closed-shell Coupled Cluster Singles and Doubles (CCSD) approach.
Further Evaluation of the Outcome Questionnaire-45.2
ERIC Educational Resources Information Center
Rice, Kenneth G.; Suh, Hanna; Ege, Engin
2014-01-01
Data from clinical and nonclinical samples ("Ns" = 2,096, 618) were used to evaluate and replicate the measurement structure of the Outcome Questionnaire-45.2. Different measurement models and invariance tests were evaluated and the best psychometric support was found for a shortened measure of two factors: overall maladjustment and…
Querying databases of trajectories of differential equations: Data structures for trajectories
NASA Technical Reports Server (NTRS)
Grossman, Robert
1989-01-01
One approach to qualitative reasoning about dynamical systems is to extract qualitative information by searching or making queries on databases containing very large numbers of trajectories. The efficiency of such queries depends crucially upon finding an appropriate data structure for trajectories of dynamical systems. Suppose that a large number of parameterized trajectories gamma of a dynamical system evolving in R sup N are stored in a database. Let Eta is contained in set R sup N denote a parameterized path in Euclidean Space, and let the Euclidean Norm denote a norm on the space of paths. A data structure is defined to represent trajectories of dynamical systems, and an algorithm is sketched which answers queries.
Multi-Center Electronic Structure Calculations for Plasma Equation of State
Wilson, B G; Johnson, D D; Alam, A
2010-12-14
We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.
Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2014-01-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level. PMID:25339790
NASA Astrophysics Data System (ADS)
Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2014-09-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level.
NASA Astrophysics Data System (ADS)
White, R. D.; Robson, R. E.; Nicoletopoulos, P.; Dujko, S.
2012-05-01
The Franck-Hertz experiment with neon gas is modelled as an idealised steady-state Townsend experiment and analysed theoretically using (a) multi-term solution of Boltzmann equation and (b) Monte-Carlo simulation. Theoretical electron periodic electron structures, together with the `window' of reduced fields in which they occur, are compared with experiment, and it is explained why it is necessary to account for all competing scattering processes in order to explain the observed experimental `wavelength'. The study highlights the fundamental flaws in trying to explain the observations in terms of a single, assumed dominant electronic excitation process, as is the case in text books and the myriad of misleading web sites.
Stenling, Andreas; Ivarsson, Andreas; Hassmén, Peter; Lindwall, Magnus
2015-01-01
In the present work we investigated distinct sources of construct-relevant psychometric multidimensionality in two sport-specific measures of coaches' need-supportive (ISS-C) and controlling interpersonal (CCBS) styles. A recently proposed bifactor exploratory structural equation modeling (ESEM) framework was employed to achieve this aim. In Study 1, using a sample of floorball players, the results indicated that the ISS-C can be considered as a unidimensional measure, with one global factor explaining most of the variance in the items. In Study 2, using a sample of male ice hockey players, the results indicated that the items in the CCBS are represented by both a general factor and specific factors, but the subscales differ with regard to the amount of variance in the items accounted for by the general and specific factors. These results add further insight into the psychometric properties of these two measures and the dimensionality of these two constructs. PMID:26388808
Stenling, Andreas; Ivarsson, Andreas; Hassmén, Peter; Lindwall, Magnus
2015-01-01
In the present work we investigated distinct sources of construct-relevant psychometric multidimensionality in two sport-specific measures of coaches' need-supportive (ISS-C) and controlling interpersonal (CCBS) styles. A recently proposed bifactor exploratory structural equation modeling (ESEM) framework was employed to achieve this aim. In Study 1, using a sample of floorball players, the results indicated that the ISS-C can be considered as a unidimensional measure, with one global factor explaining most of the variance in the items. In Study 2, using a sample of male ice hockey players, the results indicated that the items in the CCBS are represented by both a general factor and specific factors, but the subscales differ with regard to the amount of variance in the items accounted for by the general and specific factors. These results add further insight into the psychometric properties of these two measures and the dimensionality of these two constructs. PMID:26388808
Seaman, B.T.; Carr, L.D.; Holland, M.J.
2005-03-01
All Bloch states of the mean field of a Bose-Einstein condensate in the presence of a one-dimensional lattice are presented in closed analytic form. The band structure is investigated by analyzing the stationary states of the nonlinear Schroedinger, or Gross-Pitaevskii, equation for both repulsive and attractive condensates. The appearance of swallowtails in the bands is examined and interpreted in terms of the condensates superfluid properties. The nonlinear stability properties of the Bloch states are described and the stable regions of the bands and swallowtails are mapped out. We find that the Kronig-Penney potential has the same properties as a sinusoidal potential. Bose-Einstein condensates are trapped in sinusoidal optical lattices. The Kronig-Penney potential has the advantage of being analytically tractable, unlike the sinusoidal potential, and, therefore, serves as a good model for understanding experimental phenomena.
Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark
2013-07-25
The cis and trans conformation of a branched cyclic hydrocarbon affects the packing and, hence, the density, exhibited by that compound. Reported here are density data for branched cyclohexane (C6) compounds including methylcyclohexane, ethylcyclohexane (ethylcC6), cis-1,2-dimethylcyclohexane (cis-1,2), cis-1,4-dimethylcyclohexane (cis-1,4), and trans-1,4-dimethylcyclohexane (trans-1,4) determined at temperatures up to 525 K and pressures up to 275 MPa. Of the four branched C6 isomers, cis-1,2 exhibits the largest densities and the smallest densities are exhibited by trans-1,4. The densities are modeled with the Peng–Robinson (PR) equation of state (EoS), the high-temperature, high-pressure, volume-translated (HTHP VT) PREoS, and the perturbed chain, statistical associating fluid theory (PC-SAFT) EoS. Model calculations highlight the capability of these equations to account for the different densities observed for the four isomers investigated in this study. The HTHP VT-PREoS provides modest improvements over the PREoS, but neither cubic EoS is capable of accounting for the effect of isomer structural differences on the observed densities. The PC-SAFT EoS, with pure component parameters from the literature or from a group contribution method, provides improved density predictions relative to those obtained with the PREoS or HTHP VT-PREoS. However, the PC-SAFT EoS, with either set of parameters, also cannot fully account for the effect of the C6 isomer structure on the resultant density.
Development and Preliminary Validation of Chinese Preschoolers’ Eating Behavior Questionnaire
Zhang, Yuhai; Wang, Baoxi; Sun, Lijun; Shang, Lei
2014-01-01
Background The objective of this study was to develop a questionnaire for caregivers to assess the eating behavior of Chinese preschoolers. Methods To assess children’s eating behaviors, 152 items were derived from a broad review of the literature related to epidemiology surveys and the assessment of children’s eating behaviors. All of these items were reviewed by 50 caregivers of preschoolers and 10 experienced pediatricians. Seventy-seven items were selected for use in a primary questionnaire. After conducting an exploratory factor analysis and a variability analysis on the data from 313 preschoolers used to evaluate this primary questionnaire, we deleted 39 of these 77 items. A Chinese Preschoolers’ Eating Behavior Questionnaire (CPEBQ) was finally established from the remaining 38 items. The structure of this questionnaire was explored by factor analysis, and its reliability, validity and discriminative ability were evaluated with data collected from caregivers of 603 preschoolers. Results The CPEBQ consisted of 7 dimensions and 38 items. The 7 dimensions were food fussiness, food responsiveness, eating habit, satiety responsiveness, exogenous eating, emotional eating and initiative eating. The Cronbach’s ? coefficient for the questionnaire was 0.92, and the test-retest reliability was 0.72. There were significant differences between the scores of normal-weight, overweight and obese preschoolers when it was referred to food fussiness, food responsiveness, eating habits, satiety responsiveness and emotional eating (p<0.05). Differences in caregiver’s education levels also had significant effects on scores for food fussiness, eating habits and exogenous eating (p<0.05). Conclusions The CPEBQ satisfies the conditions of reliability and validity, in accordance with psychometric demands. The questionnaire can be employed to evaluate the characteristics of Chinese preschoolers’ eating behaviors; therefore, it can be used in child health care practice and research. PMID:24520359
Colibazzi, Tiziano; Zhu, Hongtu; Bansal, Ravi; Schultz, Robert T.; Wang, Zhishun; Peterson, Bradley S.
2008-01-01
Previous studies have investigated patterns of volumetric covariance (i.e. intercorrelation) among brain regions. Methodological issues, however, have limited the validity and generalizability of findings from these prior studies. Additionally, patterns of volumetric covariance have often been assumed to reflect the presence of structural networks, but this assumption has never been tested formally. We identified patterns of volumetric covariance, correlated these patterns with behavioral measures, and tested the hypothesis that the observed patterns of covariance reflect the presence of underlying networks. Specifically, we performed factor analysis on regional brain volumes of 99 healthy children and adults, and we correlated factor scores with scores on the Stroop Word-Color Interference Test. We identified four latent volumetric systems in each hemisphere: dorsal cortical, limbic, posterior, and basal ganglia. The positive correlation of the right posterior system with Stroop scores suggested that larger latent volumes are detrimental to inhibitory control. We also applied Structural Equation Modeling (SEM) to our dataset (n = 107) to test whether a model based on the anatomical pathways within cortico-striatal-thalamic-cortical (CSTC) circuits accounts for the covariances observed in our sample. The degree to which SEM predicted volumetric covariance in the CSTC circuit depended on whether we controlled for age and whole brain volume in the analyses. Removing the effects of age worsened the fit of the model, pointing to a possible developmental component in establishing connections within CSTC circuits. These modeling techniques may prove useful in the future for the study of structural networks in disease populations. PMID:17935179
NASA Astrophysics Data System (ADS)
Hollingshead, Kyle B.; Truskett, Thomas M.
2015-04-01
We use molecular dynamics simulations to test integral equation theory predictions for the structure of fluids of spherical particles with eight different piecewise-constant pair-interaction forms comprising a hard core and a combination of two shoulders and/or wells. Since model pair potentials like these are of interest for discretized or coarse-grained representations of effective interactions in complex fluids (e.g., for computationally intensive inverse optimization problems), we focus here on assessing how accurately their properties can be predicted by analytical or simple numerical closures including Percus-Yevick, hypernetted-chain, and reference hypernetted-chain closures and first-order mean spherical and modified first-order mean spherical approximations. To make quantitative comparisons between the predicted and simulated radial distribution functions, we introduce a cumulative structural error metric. For equilibrium fluid state points of these models, we find that the reference hypernetted-chain closure is the most accurate of the tested approximations as characterized by this metric or related thermodynamic quantities.
NASA Astrophysics Data System (ADS)
Uchiyama, Yusuke; Konno, Hidetoshi
2014-04-01
Defect turbulence described by the one-dimensional complex Ginzburg-Landau equation is investigated and analyzed via a birth-death process of the local structures composed of defects, holes, and modulated amplitude waves (MAWs). All the number statistics of each local structure, in its stationary state, are subjected to Poisson statistics. In addition, the probability density functions of interarrival times of defects, lifetimes of holes, and MAWs show the existence of long-memory and some characteristic time scales caused by zigzag motions of oscillating traveling holes. The corresponding stochastic process for these observations is fully described by a non-Markovian master equation.
New York Community Environment Study Questionnaire.
ERIC Educational Resources Information Center
Glaser, Daniel; Snow, Mary
This questionnaire assesses neighborhood drug problem concern, drug use practices, knowledge of drugs and agencies dealing with drugs, and views on drug education in persons aged 13 or older. The questionnaire has 31 items (multiple-choice or free response), most with several parts. The items deal with demographic and personal data, problems in…
Applying Learning Strategy Questionnaires: Problems and Possibilities
ERIC Educational Resources Information Center
Schellings, Gonny
2011-01-01
This article discusses measuring learning strategies by means of questionnaires. In "multi-method" research, in which think-aloud measures are compared with questionnaires, low or moderate correlations are found. A conclusion often drawn is that learners are not able to verbally report on their learning activities. Alternative explanations concern…
Name of Audit Self-Assessment Questionnaire
New Mexico, University of
Name of Audit Self-Assessment Questionnaire Audit Number Self-Assessment Questionnaire BD-2 1 of 8 from you so that Internal Audit can effectively determine the correct level and areas of focus of their activity in the upcoming audit of your area. Your input is important and appreciated. Please return
ERIC Educational Resources Information Center
Moulding, Richard; Anglim, Jeromy; Nedeljkovic, Maja; Doron, Guy; Kyrios, Michael; Ayalon, Ariel
2011-01-01
The study aimed to examine the factor structure of the Obsessive Beliefs Questionnaire (OBQ), the most widely used measure of dysfunctional beliefs in obsessive-compulsive disorder (OCD). Multiple exploratory methods (exploratory factor analysis, cluster analysis by variable, multidimensional scaling) were used to examine the questionnaire.…
ERIC Educational Resources Information Center
Honey, Emma; McConachie, Helen; Turner, Michelle; Rodgers, Jacqui
2012-01-01
The repetitive behaviour questionnaire (RBQ) (Turner, 1995) is one of the three most commonly used interview/questionnaire measures of repetitive behaviour (Honey et al., in preparation). Despite this there is a scarcity of information concerning its structure, reliability and validity. The psychometric properties of the RBQ were examined when…
Psychometric Properties of the Portuguese Version of the Quality of Life Questionnaire (QOL-Q)
ERIC Educational Resources Information Center
Albuquerque, Cristina P.
2012-01-01
Background: This study analyzes the psychometric properties of the Portuguese version of the Quality of Life Questionnaire (QOL-Q; Quality of Life Questionnaire Manual--1993 Manual and 2004 Revision. 2004, IDS Publishing Company, Worthington, OH; Schalock & Keith 2004). Method: The analysis of the factorial structure was carried out on a sample of…
Diet History Questionnaire II and Canadian Diet History Questionnaire II: Coding Guidelines
A questionnaire data file is an ASCII text file containing data from completed Diet History Questionnaires. If using paper forms, this file can be created by a scanner or a data entry system. If using DHQ*Web, the questionnaire data file is created automatically.
Tice, Julie Anne Goodwin
1996-01-01
, construct validity evidence was first examined at the subscale item-level and then at the higher-order construct level. The research sample included employees (N=298) of a large Midwestern corporation who responded to questionnaire items measuring the global...
ERIC Educational Resources Information Center
Amzat, Ismail Hussein; Idris, Datuk Abdul Rahman
2012-01-01
Purpose: The purpose of this paper is to discuss the effect of management and decision-making styles on the job satisfaction of academic staff in a Malaysian Research University. Design/methodology/approach: The sample consisted of 218 respondents. The instruments used in the study were the Teacher Job Satisfaction Questionnaire and the Decision…
ERIC Educational Resources Information Center
Zhang, Limei; Zhang, Lawrence Jun
2013-01-01
This article investigates the relationships between test takers' strategy use and test performance on an EFL reading test. For this study 209 Chinese college students were invited to participate in a reading comprehension test and answer a 30-item strategy use questionnaire. Results showed that two factors underlay test takers' reading test…
ERIC Educational Resources Information Center
Schweizer, Karl
2008-01-01
Structural equation modeling provides the framework for investigating experimental effects on the basis of variances and covariances in repeated measurements. A special type of confirmatory factor analysis as part of this framework enables the appropriate representation of the experimental effect and the separation of experimental and…
ERIC Educational Resources Information Center
King, Daniel W.; King, Lynda A.; McArdle, John J.; Shalev, Arieh Y.; Doron-LaMarca, Susan
2009-01-01
Depression and posttraumatic stress disorder (PTSD) are highly comorbid conditions that may arise following exposure to psychological trauma. This study examined their temporal sequencing and mutual influence using bivariate latent difference score structural equation modeling. Longitudinal data from 182 emergency room patients revealed level of…
ERIC Educational Resources Information Center
Leite, Walter L.; Zuo, Youzhen
2011-01-01
Among the many methods currently available for estimating latent variable interactions, the unconstrained approach is attractive to applied researchers because of its relatively easy implementation with any structural equation modeling (SEM) software. Using a Monte Carlo simulation study, we extended and evaluated the unconstrained approach to…
ERIC Educational Resources Information Center
Oh, Hyeon-Joo; Glutting, Joseph J.; Watkins, Marley W.; Youngstrom, Eric A.; McDermott, Paul A.
2004-01-01
In this study, the authors used structural equation modeling to investigate relationships between ability constructs from the "Wechsler Intelligence Scale for Children-Third Edition" (WISC-III; Wechsler, 1991) in explaining reading and mathematics achievement constructs on the "Wechsler Individual Achievement Test" (WIAT; Wechsler, 1992).…
ERIC Educational Resources Information Center
de Guzman, Allan B.; Ines, Joanna Louise C.; Inofinada, Nina Josefa A.; Ituralde, Nielson Louie J.; Janolo, John Robert E.; Jerezo, Jnyv L.; Jhun, Hyae Suk J.
2013-01-01
While a number of empirical studies have been conducted regarding risk for falls among the elderly, there is still a paucity of similar studies in a developing country like the Philippines. This study purports to test through Structural Equation Modeling (SEM) a model that shows the interaction between and among nutrition, balance, fear of…
ERIC Educational Resources Information Center
Enders, Craig K.
2005-01-01
The Bollen-Stine bootstrap can be used to correct for standard error and fit statistic bias that occurs in structural equation modeling (SEM) applications due to nonnormal data. The purpose of this article is to demonstrate the use of a custom SAS macro program that can be used to implement the Bollen-Stine bootstrap with existing SEM software.…
ERIC Educational Resources Information Center
Enders, Craig K.; Peugh, James L.
2004-01-01
Two methods, direct maximum likelihood (ML) and the expectation maximization (EM) algorithm, can be used to obtain ML parameter estimates for structural equation models with missing data (MD). Although the 2 methods frequently produce identical parameter estimates, it may be easier to satisfy missing at random assumptions using EM. However, no…
Total dietary fat and saturated fat intake are associated with obesity, elevated cholesterol, and heart disease. This study tested a multi-group structural equation model to explore differences in the relative influence of individual, social, and physical environment factors on dietary fat intake amongst adults aged 40-70 years.
ERIC Educational Resources Information Center
Yu, Baohua
2013-01-01
This study examined the interrelationships of integrative motivation, competence in second language (L2) communication, sociocultural adaptation, academic adaptation and persistence of international students at an Australian university. Structural equation modelling demonstrated that the integrative motivation of international students has a…
ERIC Educational Resources Information Center
Crano, William D.; Mendoza, Jorge L.
1987-01-01
An analysis using data drawn from Nancy Bayley's Berkeley Growth Study is performed for didactic purposes to illustrate the use of structural equation modeling on a child development data set. Alternatives to standard latent factor approaches are demonstrated for use in research situations in which the subject-to-variable ratio is less than…
Leipply, Desirae; Draper, David E
2010-03-01
The Mg(2+)-induced folding of RNA tertiary structures is readily observed via titrations of RNA with MgCl(2). Such titrations are commonly analyzed using a site binding formalism that includes a parameter, the Hill coefficient n, which is sometimes deemed the number of Mg(2+) ions bound by the native RNA at specific sites. However, the long-range nature of electrostatic interactions allows ions some distance from the RNA to stabilize an RNA structure. A complete description of all interactions taking place between Mg(2+) and an RNA uses a preferential interaction coefficient, Gamma(2+), which represents the "excess" Mg(2+) neutralizing the RNA charge. The difference between Gamma(2+) for the native and unfolded RNA forms (DeltaGamma(2+)) is the number of Mg(2+) ions "taken up" by an RNA upon folding. Here we determine the conditions under which the Hill coefficient n can be equated to the ion uptake DeltaGamma(2+) and find that two approximations are necessary: (i) the Mg(2+) activity coefficient is independent of concentration during a titration, and (ii) the dependence of DeltaGamma(2+) on Mg(2+) concentration is weak. Titration experiments with a Mg(2+)-binding dye and an adenine-binding riboswitch were designed to test these approximations. Inclusion of a 30-fold excess of KCl over MgCl(2) was sufficient to maintain a constant Mg(2+) activity coefficient. We also observed that Mg(2+) uptake by the RNA varied from near zero to approximately 2.6 as the Mg(2+) concentration increases over an approximately 100-fold range. It is possible to determine DeltaGamma(2+) from Mg(2+)-RNA titrations, but the values are only applicable to a limited range of solution conditions. PMID:20112919
Leipply, Desirae; Draper, David E.
2010-01-01
The Mg2+-induced folding of RNA tertiary structures is readily observed via titrations of RNA with MgCl2. Such titrations are commonly analyzed using a site-binding formalism that includes a parameter, the Hill coefficient n, which is sometimes deemed the number of Mg2+ ions bound by the native RNA at specific sites. However, the long-range nature of electrostatic interactions allows ions some distance from the RNA to stabilize an RNA structure. A complete description of all interactions taking place between Mg2+ and an RNA uses a preferential interaction coefficient, ?2+, which represents the 'excess' Mg2+ neutralizing the RNA charge. The difference between ?2+ for the native and unfolded RNA forms (??2+) is the number of Mg2+ ions ‘taken up’ by an RNA upon folding. Here we ask under what conditions the Hill coefficient n can be equated to the ion uptake ??2+, and find that two approximations are necessary: (i) the Mg2+ activity coefficient is independent of concentration during a titration, and (ii) the dependence of ??2+ on Mg2+ concentration is weak. Titration experiments with a Mg2+-binding dye and an adenine-binding riboswitch were designed to test these approximations. Inclusion of a 30-fold excess of KCl over MgCl2 was sufficient to maintain a constant Mg2+ activity coefficient. We also observed that Mg2+ uptake by the RNA varied from near zero to ~2.6 as the Mg2+ concentration increases over ~100-fold range. It is possible to determine ??2+ from Mg2+ - RNA titrations, but the values are only applicable to a limited range of solution conditions. PMID:20112919
Bardenheier, Barbara H.; Bullard, Kai McKeever; Caspersen, Carl J.; Cheng, Yiling J.; Gregg, Edward W.; Geiss, Linda S.
2013-01-01
OBJECTIVE To use structural modeling to test a hypothesized model of causal pathways related with prediabetes among older adults in the U.S. RESEARCH DESIGN AND METHODS Cross-sectional study of 2,230 older adults (?50 years) without diabetes included in the morning fasting sample of the 2001–2006 National Health and Nutrition Examination Surveys. Demographic data included age, income, marital status, race/ethnicity, and education. Behavioral data included physical activity (metabolic equivalent hours per week for vigorous or moderate muscle strengthening, walking/biking, and house/yard work), and poor diet (refined grains, red meat, added sugars, solid fats, and high-fat dairy). Structural-equation modeling was performed to examine the interrelationships among these variables with family history of diabetes, high blood pressure, BMI, large waist (waist circumference: women, ?35 inches; men, ?40 inches), triglycerides ?200 mg/dL, and total and HDL (?60 mg/dL) cholesterol. RESULTS After dropping BMI and total cholesterol, our best-fit model included three single factors: socioeconomic position (SEP), physical activity, and poor diet. Large waist had the strongest direct effect on prediabetes (0.279), followed by male sex (0.270), SEP (?0.157), high blood pressure (0.122), family history of diabetes (0.070), and age (0.033). Physical activity had direct effects on HDL (0.137), triglycerides (?0.136), high blood pressure (?0.132), and large waist (?0.067); poor diet had direct effects on large waist (0.146) and triglycerides (0.148). CONCLUSIONS Our results confirmed that, while including factors known to be associated with high risk of developing prediabetes, large waist circumference had the strongest direct effect. The direct effect of SEP on prediabetes suggests mediation by some unmeasured factor(s). PMID:23649617
Pollman, Curtis D
2014-11-15
Structural equation modeling (SEM) provides a framework that can more properly handle complex variable interactions inherent in mercury cycling and its bioaccumulation compared to more traditional regression-based methods. SEM was applied to regional data sets for three different types of aquatic ecosystems within Florida, USA--lakes, streams, and the Everglades--to evaluate the underlying nature (i.e., indirect and direct) of the relationships between fish mercury concentrations and trophic state related variables such as nutrients, dissolved organic carbon (DOC), sulfate, and alkalinity. The modeling results indicated some differences in key variable relationships--for example, the effect of nutrients on fish mercury in lakes and streams was uniformly negative through direct and indirect pathways consistent with biodilution or eutrophication-associated effects on food web structure. Somewhat surprisingly, however, was that total phosphorus did not serve as a meaningful variable in the Everglades model, apparently because its effects were masked or secondary to the effects of DOC. What is perhaps a more important result were two key similarities across the three systems. First, the modeling clearly indicates that the dominant influence on fish tissue mercury concentrations in all three systems is related to variations in the methylmercury signal. Second, the modeling demonstrated that the effect of DOC on fish mercury concentrations was exerted through multiple and antagonistic pathways, including facilitated transport of total mercury and methylmercury, enhanced rates of methylation, and limitations imposed on bioavailability. Indeed, while the individual DOC pathways in the models were all highly significant (generally p<0.001), the net effect of DOC in each model was greatly reduced or insignificant. These results can help explain contradictory results obtained previously by other researchers in other systems, and illustrate the importance of SEM as a modeling tool when studying systems with complex interactions such as the aquatic mercury cycle. PMID:25173863
Geiser, Christian; Bishop, Jacob; Lockhart, Ginger; Shiffman, Saul; Grenard, Jerry L.
2013-01-01
Latent state-trait (LST) and latent growth curve (LGC) models are frequently used in the analysis of longitudinal data. Although it is well-known that standard single-indicator LGC models can be analyzed within either the structural equation modeling (SEM) or multilevel (ML; hierarchical linear modeling) frameworks, few researchers realize that LST and multivariate LGC models, which use multiple indicators at each time point, can also be specified as ML models. In the present paper, we demonstrate that using the ML-SEM rather than the SL-SEM framework to estimate the parameters of these models can be practical when the study involves (1) a large number of time points, (2) individually-varying times of observation, (3) unequally spaced time intervals, and/or (4) incomplete data. Despite the practical advantages of the ML-SEM approach under these circumstances, there are also some limitations that researchers should consider. We present an application to an ecological momentary assessment study (N = 158 youths with an average of 23.49 observations of positive mood per person) using the software Mplus (Muthén and Muthén, 1998–2012) and discuss advantages and disadvantages of using the ML-SEM approach to estimate the parameters of LST and multiple-indicator LGC models. PMID:24416023
Ravangard, Ramin; Yasami, Shamim; Shokrpour, Nasrin; Sajjadnia, Zahra; Farhadi, Payam
2015-01-01
Nurses are the largest group and an important part of the providers in the health care systems that who a key role in hospitals. Any defect and deficiency in their work can result in irreversible outcomes. This study aimed to determine the effect of supervisors' support and mediating factors on the job performance (JOBPER) of 400 nurses working in the teaching hospitals affiliated to Shiraz University of Medical Sciences, using structural equation modeling. The results showed that the supervisor's support had a significant negative effect on work-family conflict (t = -2.57) and a positive effect on organizational commitment (t = 4.03); Work-family conflict had a significant positive effect on job stress (t = 11.24) and a negative effect on organizational commitment (t = -3.35) and JOBPER (t = -2.29). Family-work conflict had a positive effect on job stress (t = 4.48) and a negative effect on organizational commitment (t = -2.54). Finally, job stress had a negative effect (t = -3.30), and organizational commitment showed a positive effect (t = 5.96) on the studied nurses' JOBPER. According to the results, supervisor's support could influence JOBPER through reducing work-family conflict and increasing organizational commitment. Therefore, to improve the nurses' JOBPER in the hospitals, some strategies are recommended. PMID:26218002
Bavarian, Niloofar; Flay, Brian R.; Ketcham, Patricia L.; Smit, Ellen; Kodama, Cathy; Martin, Melissa; Saltz, Robert F.
2014-01-01
Objective To test a theory-driven model of health behavior to predict the illicit use of prescription stimulants (IUPS) among college students. Participants A probability sample of 554 students from one university located in California (response rate = 90.52%). Methods Students completed a paper-based survey developed with guidance from the Theory of Triadic Influence. We first assessed normality of measures and checked for multicollinearity. A single structural equation model of frequency of IUPS in college was then tested using constructs from the theory’s three streams of influence (i.e., intrapersonal, social situation/context, and sociocultural environment) and four levels of causation (i.e., ultimate causes, distal influences, proximal predictors, and immediate precursors). Results Approximately 18% of students reported engaging in IUPS during college, with frequency of use ranging from never to 40 or more times per academic term. The model tested had strong fit and the majority of paths specified within and across streams were significant at the p<.01 level. Additionally, 46% of the variance in IUPS frequency was explained by the tested model. Conclusions Results suggest the utility of the TTI as an integrative model of health behavior, specifically in predicting IUPS, and provide insight on the need for multifaceted prevention and intervention efforts. PMID:24647369
Ratnam, Kalai Anand; Dominic, P D D; Ramayah, T
2014-08-01
The investments and costs of infrastructure, communication, medical-related equipments, and software within the global healthcare ecosystem portray a rather significant increase. The emergence of this proliferation is then expected to grow. As a result, information and cross-system communication became challenging due to the detached independent systems and subsystems which are not connected. The overall model fit expending over a sample size of 320 were tested with structural equation modelling (SEM) using AMOS 20.0 as the modelling tool. SPSS 20.0 is used to analyse the descriptive statistics and dimension reliability. Results of the study show that system utilisation and system impact dimension influences the overall level of services of the healthcare providers. In addition to that, the findings also suggest that systems integration and security plays a pivotal role for IT resources in healthcare organisations. Through this study, a basis for investigation on the need to improvise the Malaysian healthcare ecosystem and the introduction of a cloud computing platform to host the national healthcare information exchange has been successfully established. PMID:24957398
Chen, Yuan; Wong, Lena L. N.; Zhu, Shufeng; Xi, Xin
2015-01-01
Objective To examine the direct and indirect effects of demographical factors on speech perception and vocabulary outcomes of Mandarin-speaking children with cochlear implants (CIs). Methods 115 participants implanted before the age of 5 and who had used CI before 1 to 3 years were evaluated using a battery of speech perception and vocabulary tests. Structural equation modeling was used to test the hypotheses proposed. Results Early implantation significantly contributed to speech perception outcomes while having undergone a hearing aid trial (HAT) before implantation, maternal educational level (MEL), and having undergone universal newborn hearing screening (UNHS) before implantation had indirect effects on speech perception outcomes via their effects on age at implantation. In addition, both age at implantation and MEL had direct and indirect effects on vocabulary skills, while UNHS and HAT had indirect effects on vocabulary outcomes via their effects on age at implantation. Conclusion A number of factors had indirect and direct effects on speech perception and vocabulary outcomes in Mandarin-speaking children with CIs and these factors were not necessarily identical to those reported among their English-speaking counterparts. PMID:26348360
Wen, Xiao-Yong; Yang, Yunqing; Yan, Zhenya
2015-07-01
In this paper, a simple and constructive method is presented to find the generalized perturbation (n,M)-fold Darboux transformations (DTs) of the modified nonlinear Schrödinger (MNLS) equation in terms of fractional forms of determinants. In particular, we apply the generalized perturbation (1,N-1)-fold DTs to find its explicit multi-rogue-wave solutions. The wave structures of these rogue-wave solutions of the MNLS equation are discussed in detail for different parameters, which display abundant interesting wave structures, including the triangle and pentagon, etc., and may be useful to study the physical mechanism of multirogue waves in optics. The dynamical behaviors of these multi-rogue-wave solutions are illustrated using numerical simulations. The same Darboux matrix can also be used to investigate the Gerjikov-Ivanov equation such that its multi-rogue-wave solutions and their wave structures are also found. The method can also be extended to find multi-rogue-wave solutions of other nonlinear integrable equations. PMID:26274257
Development of the Sport Orientation Questionnaire.
ERIC Educational Resources Information Center
Gill, Diane L.; Deeter, Thomas E.
1988-01-01
An analysis of the Sport Orientation Questionnaire, a multidimensional, sport-specific measure of individual differences in achievement orientation, indicates that it is a valid and reliable measure of individual sport achievement orientation. (JD)
Physical Activity Questionnaires (PAQ) Validation Studies - References
Wareham NJ, Jakes RW, Rennie KL et al. Validity and repeatability of a simple index derived from the short physical activity questionnaire used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.
Development of the Eating Habits Questionnaire
Graham, Erin Collins
2005-02-17
The purpose of the studies presented was to develop and examine the psychometric properties of the Eating Habits Questionnaire (EHQ). The author designed the 21-item self-report inventory to assess cognitions, behaviors, and feelings related...
Data Request Questionnaire: Name of Requestor: _________________________________
Miami, University of
Data Request Questionnaire: Name of Requestor: _________________________________ Circle One:_________________________ Telephone: __________________________ Email: _____________________________ What data variables and level?___________________________________________________________________ Describe how will you use the data? By signing this document, you agree to follow the Data Policy outlined
Standardized Questionnaires of Walking & Bicycling Database
This database contains questionnaire items and a list of validation studies for standardized items concerning walking and biking from multiple national and international physical activity questionnaires (PAQs). The purpose of this database is to provide easy access to a large number of items assessing duration and frequency of walking and bicycling in the non-disabled adult population. We also briefly review the results of validation studies identified for some of the PAQs.
Validation of a maternal questionnaire on correlates of physical activity in preschool children
McMinn, Alison M.; van Sluijs, Esther M. F.; Harvey, Nicholas C.; Cooper, Cyrus; Inskip, Hazel M.; Godfrey, Keith M.; Griffin, Simon J.
2009-12-02
Abstract Background Valid measures of physical activity correlates in preschool children are lacking. This study aimed to assess the validity, factor structure and internal consistency of a maternal questionnaire on potential correlates of four...
Spanish version of the Thought-Action Fusion Questionnaire and its application in eating disorders
Jáuregui-Lobera, I; Santed-Germán, Ma; Bolaños-Ríos, P; Garrido-Casals, O
2013-01-01
Purpose The aims of the study were to analyze the psychometric properties of the Spanish version of the Thought-Action Fusion Questionnaire (TAF-SP), as well as to determine its validity by evaluating the relationship of the TAF-SP to different instruments. Patients and methods Two groups were studied: one comprising 146 patients with eating disorders; and another a group of 200 students. Results Three factors were obtained: TAF–Moral; TAF–Likelihood-others; and TAF–Likelihood-oneself. The internal consistency of the TAF-SP was determined by means of Cronbach’s ? coefficient, with values ranging between 0.84–0.95. The correlations with other instruments refected adequate validity. The three-factor structure was tested by means of a linear structural equation model, and the structure fit satisfactorily. Differences in TAF-SP scores between the diagnostic subgroups were also analyzed. Conclusion The TAF-SP meets the psychometric requirements for measuring thought-action fusion and shows adequate internal consistency and validity. PMID:24043960
Body image during pregnancy: an evaluation of the suitability of the body attitudes questionnaire
2012-01-01
Background Available data suggest that body dissatisfaction is common during pregnancy and may even be a precursor to post-natal depression. However, in order to accurately identify at-risk women, it is essential to first establish that body image measures function appropriately in pregnant populations. Our study examines the suitability of the Body Attitudes Questionnaire (BAQ) for measuring body dissatisfaction among pregnant women by comparing the psychometric functioning of the BAQ: (1) across key phases of pregnancy, and (2) between pregnant and non-pregnant women. Methods A total of 176 pregnant women from Melbourne, Victoria filled out a questionnaire battery containing demographic questions and the Body Attitudes Questionnaire at 16, 24, and 32 weeks during pregnancy. A comparison group of 148 non-pregnant women also completed the questionnaire battery at Time 1. Evaluations of the psychometric properties of the BAQ consisted of a series of measurement invariance tests conducted within a structural equation modelling framework. Results Although the internal consistency and factorial validity of the subscales of the BAQ were established across time and also in comparisons between pregnant and non-pregnant women, measurement invariance tests showed non-invariant item intercepts across pregnancy and also in comparison with the non-pregnant subgroup. Inspection of modification indices revealed a complex, non-uniform pattern of differences in item intercepts across groups. Conclusions Collectively, our findings suggest that comparisons of body dissatisfaction between pregnant and non-pregnant women (at least based on the BAQ) are likely to be conflated by differential measurement biases that serve to undermine attempts to accurately assess level of body dissatisfaction. Researchers should be cautious in assessments of body dissatisfaction among pregnant women until a suitable measure has been established for use in this population. Given the fact that body dissatisfaction is often associated with maladaptive behaviours, such as unhealthy eating and extreme weight loss behaviours, and with ante-and post-natal depression, that have serious negative implications for women’s health and well-being, and potentially also for the unborn foetus during pregnancy, developing a suitable body image screening tool, specific to the perinatal period is clearly warranted. PMID:22950761
Owili, Patrick Opiyo; Hsu, Yi-Hsin Elsa; Chern, Jin-Yuan; Chiu, Chiung-Hsuan Megan; Wang, Bill; Huang, Kuo-Cherh; Muga, Miriam Adoyo
2015-01-01
Background Health care resource allocation is key towards attaining equity in the health system. However, health professionals’ perceived impact and attitude towards health care resource allocation in Sub-Saharan Africa is unknown; furthermore, they occupy a position which makes them notice the impact of different policies in their health system. This study explored perceptions and attitudes of health professionals in Kenya on health care resource allocation mechanism. Method We conducted a survey of a representative sample of 341 health professionals in Moi Teaching and Referral Hospital from February to April 2012, consisting of over 3000 employees. We assessed health professionals’ perceived impact and attitudes on health care resource allocation mechanism in Kenya. We used structural equation modeling and applied a Confirmatory Factor Analysis using Robust Maximum Likelihood estimation procedure to test the hypothesized model. Results We found that the allocation mechanism was negatively associated with their perceived positive impact (-1.04, p < .001), health professionals’ satisfaction (-0.24, p < .01), and professionals’ attitudes (-1.55, p < .001) while it was positively associated with perceived negative impact (1.14, p < .001). Perceived positive impact of the allocation mechanism was negatively associated with their overall satisfaction (-0.08) and attitude (-0.98) at p < .001, respectively. Furthermore, overall satisfaction was negatively associated with attitude (-1.10, p <.001). On the other hand, perceived negative impact of the allocation was positively associated with overall satisfaction (0.29, p <.001) but was not associated with attitude. Conclusion The result suggests that health care resource allocation mechanism has a negative effect towards perceptions, attitudes and overall satisfaction of health professionals who are at the frontline in health care. These findings can serve as a crucial reference for policymakers as the Kenyan health system move towards devolving the system of governance. PMID:26039053
Lin, Fa-Hsuan; Agnew, John A.; Belliveau, John W.; Zeffiro, Thomas A.
2010-01-01
Tasks employing parametric variation in movement rate are associated with predictable modulations in neural activity, and provide a convenient context for developing new techniques for system identification. Using a multistage approach, we explored the functional and effective connectivity of a visuomotor control system by combining generalized partial least squares (gPLS) with subsequent structural equation modeling (SEM) to reveal the relationships between neural activity and finger movement rate in an experiment involving visually-paced left or right thumb flexion. The gPLS in the first analysis stage automatically identified spatially distributed sets of BOLD-contrast signal changes using linear combinations of sigmoidal basis functions parameterized by kinematic variables. The gPLS provided superior sensitivity in detecting task-related functional activity patterns via a step-wise comparison with both classical linear modeling and behavior correlation analysis. These activity patterns were used in the second analysis stage, which employed SEM to characterize the areal regional interactions. The hybrid gPLS/SEM procedure allowed modeling of complex regional interactions in a network including primary motor cortex, premotor areas, cerebellum, thalamus, and basal ganglia, with differential activity modulations with respect to rate observed in the corticocerebellar and corticostriate subsystems. This effective connectivity analysis of visuomotor control circuits showed that both the left and right corticocerebellar and corticostriate circuits exhibited movement rate-related modulation. The identification of the functional connectivity among regions participating particular classes of behavior using gPLS, followed by the estimation of the effective connectivity using SEM is an efficient means to characterize the neural interactions underlying variations in sensorimotor behavior. PMID:19288462
NASA Astrophysics Data System (ADS)
Parra-Rivas, P.; Gomila, D.; Matías, M. A.; Coen, S.; Gelens, L.
2014-04-01
It has been recently uncovered that coherent structures in microresonators such as cavity solitons and patterns are intimately related to Kerr frequency combs. In this work, we present a general analysis of the regions of existence and stability of cavity solitons and patterns in the Lugiato-Lefever equation, a mean-field model that finds applications in many different nonlinear optical cavities. We demonstrate that the rich dynamics and coexistence of multiple solutions in the Lugiato-Lefever equation are of key importance to understanding frequency comb generation. A detailed map of how and where to target stable Kerr frequency combs in the parameter space defined by the frequency detuning and the pump power is provided. Moreover, the work presented also includes the organization of various dynamical regimes in terms of bifurcation points of higher codimension in regions of parameter space that were previously unexplored in the Lugiato-Lefever equation. We discuss different dynamical instabilities such as oscillations and chaotic regimes.
ERIC Educational Resources Information Center
Schembre, Susan M.; Riebe, Deborah A.
2011-01-01
Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO[subscript 2]max) as well as sub-maximal exercise testing. The International Physical Activity Questionnaire is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO[subscript…
NHEXAS PHASE I MARYLAND STUDY--TECHNICIAN WALKTHROUGH QUESTIONNAIRE DATA
The Technician Walkthrough questionnaire data set contains information about each household as determined during a walkthrough by trained technicians. The information is from 403 technician walkthrough questionnaires for 80 households across 6 cycles. The questionnaire includes...
NHEXAS PHASE I ARIZONA STUDY--BASELINE QUESTIONNAIRE DATA
The Baseline Questionnaire data set provides information about the household using the primary resident (IRN 01) and other residents who chose to participate. The information is from 1106 Baseline Questionnaires for 534 households. The Baseline Questionnaire was administered to...
77 FR 39986 - Information Collection; Health Screening Questionnaire
Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-06
... Forest Service Information Collection; Health Screening Questionnaire AGENCY: Forest Service, USDA... a currently approved information collection, Health Screening Questionnaire. DATES: Comments must be...: Title: Health Screening Questionnaire. OMB Number: 0596-0164. Expiration Date of Approval: January...
Reliability and Validity of the Iranian Version of Nijmegen Questionnaire in Iranians with Asthma
Ravanbakhsh, Majid; Raji, Hanieh; Haddadzadeh Shoushtari, Maryam
2015-01-01
Background: The aim of this study was to assess the validity and reliability of Nijmegen questionnaire (NQ) translated to Farsi for diagnosis of the hyperventilation syndrome (HVS) in patients with asthma. Materials and Methods: The original version of NQ was translated to Farsi and then back-translated to English again to assess its agreement with the original version. To determine its cultural adaptation, a pilot study was carried out. The mean score of the questionnaire and the mean pressure of end tidal carbon dioxide (PETCO2) were compared in 100 asthmatic patients to determine the validity of the questionnaire. For reliability, 52 out of 100 patients randomly filled out the questionnaire with an interval of 5 to 10 days. Internal consistency and content validity of the questionnaire were assessed by Cronbach’s alpha coefficient and by calculating floor and ceiling effects respectively. The exploratory factor analysis was used to assess the factor structure. Results: There was a significant inverse correlation between NQ scores and PETCO2 (P=?0.783). Cronbach’s alpha coefficient was greater than 0.7, indicating good internal consistency of the questionnaire (P=0.702). The questionnaire had a good stability in an interval of 5 to 10 days (P=0.826). The NQ had no floor and ceiling effect. and also factor analysis of 16 scales showed that this questionnaire has a five-factor structure, which can describe 55% of data variance. Conclusion: The Iranian version of the Nijmegen questionnaire is a valid and reliable tool for detection of patients with HVS. In addition, the questionnaire can be used to evaluate the condition of respiratory function in people with asthma. PMID:26528366
Bogdan G. Dimitrov
2008-10-29
In this paper a new block-structure method is presented for the solution of the well-known from gravity theory matrix system of equations g{ij}g{jk}=delta{i}{k} (with respect to the unknown covariant components g{ij} and by known contravariant ones g{jk}) by transforming this matrix system into a linear algebraic system of equations in the general N-dimensional case. Although powerful computer methods exist for the solution of this problem for a given (fixed) dimension of the matrices g{ij} and especially for numerical elements of g{ij}, the structure of the obtained linear algebraic system in the general N-dimensional case and for arbitrary elements of g{ij} (functions) has not been known. The proposed new analytical block-structure method for the case of symmetrical matrices g{ij} and g{jk} (the standard case in gravity theory) is based on the construction of a block-structure matrix, whose "elements" are again matrices. The method allows to obtain the structure of this linear system in the general N-dimensional case, after multiplication (to the left) with the transponed matrix. Some arguments are given why the proposed method may be applied, after some refinement and generalization for the case of non-symmetrical matrices g{ij} and g{jk}, for finding the graviton modes in the Kaluza-Klein expansion in theories with extra dimensions.
ERIC Educational Resources Information Center
Thompson, Janny M.; Blain, Michelle D.
1992-01-01
Describes visual method for condensing and presenting feedback to career counseling clients on their vocational needs and satisfaction as assessed by Minnesota Importance Questionnaire paired form and long-form Minnesota Satisfaction Questionnaire. Describes instruments and their place in career counseling and illustrates use of satisfaction x…
NASA Astrophysics Data System (ADS)
Kengne, Emmanuel; Lakhssassi, Ahmed
2015-10-01
Motivated by recent experimental investigations in the context of matter wave solitons in Bose-Einstein condensates (BECs), we consider the 1+1 Gross-Pitaevskii equation with complex time-varying harmonic potential, and time-varying cubic and quintic nonlinearities. By performing a modified lens-type transformation for the one-dimensional GP equation, we present one and/or two parameter exact analytical solutions which describe the propagation of bright, kink, and dark solitary waves on the vanishing continuous wave (cw) background. Based on exact analytical solutions of the GP equation, we investigate analytically the dynamics of matter-wave solitons in the BEC systems. Our studies show that the solitons' amplitude depends on both the scattering length and the feeding/loss term of the potential while their motion depends on the external trapping potential and solution parameters.
Knowledge Elecitation for Factors Affecting Taskforce Productivity using a Questionnaire
Muhammad Sohail; Abdur Rashid Khan
2009-07-30
In this paper we present the process of Knowledge Elicitation through a structured questionnaire technique. This is an effort to depict a problem domain as Investigation of factors affecting taskforce productivity. The problem has to be solved using the expert system technology. This problem is the very first step how to acquire knowledge from the domain experts. Knowledge Elicitation is one of the difficult tasks in knowledge base formation which is a key component of expert system. The questionnaire was distributed among 105 different domain experts of Public and Private Organizations (i.e. Education Institutions, Industries and Research etc) in Pakistan. A total 61 responses from these experts were received. All the experts were well qualified, highly experienced and has been remained the members for selection committees a number of times for different posts. Facts acquired were analyzed from which knowledge was extracted and elicited. A standard shape was given to the questionnaire for further research as a knowledge learning tool. This tool may be used as a standard document for selection and promotion of employees.
The study on the outsourcing of Taiwan's hospitals: a questionnaire survey research
Hsiao, Chih-Tung; Pai, Jar-Yuan; Chiu, Hero
2009-01-01
Background The aim of this study was to assess the outsourcing situation in Taiwanese hospitals and compares the differences in hospital ownership and in accreditation levels. Methods This research combined two kinds of methods: a questionnaire survey and the in-depth interview to two CEOs of the sample hospitals. One hospital is not-for-profit, while the other is a public hospital and the research samples are from the hospital data from Taiwan's 2005 to 2007 Department of Health qualifying lists of hospital accreditation. The returned questionnaires were analyzed with STATISTICA® 7.1 version software. Results The results for non-medical items showed medical waste and common trash both have the highest rate (94.6 percent) of being outsourced. The gift store (75 percent) and linen (73 percent) follow close behind, while the lowest rate of outsourcing is in utility maintenance (13.5 percent). For medical items, the highest rate of outsourcing is in the ambulance units (51.4 percent), while the hemodialysis center follows close behind with a rate of 50 percent. For departments of nutrition, pharmacy, and nursing however, the outsourcing rate is lower than 3 percent. This shows that Taiwan's hospitals are still conservative in their willingness to outsource for medical items. The results of the satisfaction paired t-test show that the non-medical items have a higher score than the medical items. The factor analysis showed the three significant factors in of non medical items' outsourcing are "performance", "finance", and "human resource". For medical items, the two factors are "operation" and satisfaction". To further exam the factor validity and reliability of the satisfaction model, a confirmative factor analysis (CFA) was conducted using structure equation modeling (SEM) method and found the model fitting well. Conclusion Hospitals, especially for public hospitals, can get benefits from outsourcing to revive the full-time-equivalent and human resource limitation. PMID:19435526
University of Michigan Drug Education Questionnaire.
ERIC Educational Resources Information Center
Francis, John Bruce; Patch, David J.
This questionnaire assesses attitudes toward potential drug education programs and drug use practices in college students. The 87 items (multiple choice or free response) pertain to the history and extent of usage of 27 different drugs, including two non-existent drugs which may be utilized as a validity check; attitude toward the content, format,…
Caregivers feeding styles questionnaire. Establishing cutoff points
Technology Transfer Automated Retrieval System (TEKTRAN)
Researchers use the Caregiver's Feeding Styles Questionnaire (CFSQ) to categorize parent feeding into authoritative, authoritarian, indulgent, and uninvolved styles. The CFSQ assesses self-reported feeding and classifies parents using median splits which are used in a substantial body of parenting l...
IRON AND STEEL EFFLUENT GUIDELINES ECONOMIC QUESTIONNAIRE
Resource Purpose:This information acquired via the questionnaire is used to support development of the effluent guidelines for the Iron and Steel Point Source Category (40CFR Part 420). One of the statutory decision criteria for the adoption of a best available treatment t...
The Personal Attributes Questionnaire: A Conceptual Analysis.
ERIC Educational Resources Information Center
Ozer, Daniel
The rich complexity of the concepts of masculinity and femininity has been reflected in personality measures in at least two different ways: by employing a variety of subscales with comparatively homogeneous items or by using a single scale with comparatively heterogeneous items. The Personal Attributes Questionnaire (PAQ) was the subject of an…
Utah Drop-Out Drug Use Questionnaire.
ERIC Educational Resources Information Center
Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.
This questionnaire assesses drug use practices in high school drop-outs. The 79 items (multiple choice or apply/not apply) are concerned with demographic data and use, use history, reasons for use/nonuse, attitudes toward drugs, availability of drugs, and drug information with respect to narcotics, amphetamines, LSD, Marijuana, and barbiturates.…
INSURANCE & CLAIMS MANAGEMENT SPECIAL EVENTS QUESTIONNAIRE
Li, Mo
INSURANCE & CLAIMS MANAGEMENT SPECIAL EVENTS QUESTIONNAIRE TODAY'S DATE: / / 1. TITLE OF EVENT: 2. EVENT DATE (S): HOURS: 3. DESCRIBE EVENT: 4. SPONSORING ORGANIZATION: 5. ADDRESS: 6. CONTACT PERSON. OF PARTICIPANTS: NUMBER OF PARTICIPANTS UNDER 18: APPROXIMATE NO. OF EVENT ATTENDEES: 9. ANY VEHICLES INVOLVED
Canadian Version of the Diet History Questionnaire
The Diet History Questionnaire (DHQ) and the DHQ nutrient database were modified for use in Canada through the collaborative efforts of Dr. Amy Subar and staff at the Risk Factor Monitoring and Methods Branch, and Dr. Ilona Csizmadi and colleagues in the Division of Population Health and Information at the Alberta Cancer Board in Canada.
Validation of the Child Sport Cohesion Questionnaire
ERIC Educational Resources Information Center
Martin, Luc J.; Carron, Albert V.; Eys, Mark A.; Loughead, Todd
2013-01-01
The purpose of the present study was to test the validity evidence of the Child Sport Cohesion Questionnaire (CSCQ). To accomplish this task, convergent, discriminant, and known-group difference validity were examined, along with factorial validity via confirmatory factor analysis (CFA). Child athletes (N = 290, M[subscript age] = 10.73 plus or…
Diet History Questionnaire Paper-based Forms
DHQ-1 is the standard version of the NCI's Diet History Questionnaire. It was originally printed in 1998, reprinted in 2002 with minor changes to the front page and the development of a Spanish translation, and reprinted again in 2007 with changes to the Today's Date field to include the years 2007-2011.
Applicant Questionnaire for admission to the
British Columbia, University of
) 1. Have you taken university-level courses in the following subjects? Biology Chemistry Physics taxonomic keys to classify soils? Measured tree dimensions? Advised a client or employer on a business for overcoming these gaps? NOTE: this questionnaire is only part of the supporting documentation required
ANNUAL MEDICAL HISTORY QUESTIONNAIRE FOR RESPIRATOR USE
Slatton, Clint
ANNUAL MEDICAL HISTORY QUESTIONNAIRE FOR RESPIRATOR USE Occupational Medicine Program Name: UFID Telephone Number: Describe any apparent difficulties noted with respirator use, if any: Have you had or do that might interferewith respirator use or result in limited work ability 18. Are you taking any medications
Cardiff's TELEform: Scanning the Diet History Questionnaire
Software, such as Cardiff's TELEform Information Capture System, is available to create and print a scannable version of the Diet History Questionnaire form. To create booklets, you may still need to hire a professional printer. Using TELEform, you will be able to scan the instrument with an imaging scanner (contact Cardiff for specifications).
Language Usage Questionnaire, Ethiopian Schoolchildren. Draft.
ERIC Educational Resources Information Center
Ferguson, Charles A.; And Others
The questionnaire presented here was designed to be administered to a representative sample of Ethiopian children enrolled in primary and secondary schools. Responses to be elicited pertain to --(1) personal use of language in several domains of speech behavior, (2) use of language by others in situations which the respondent has had an…
The Knowledge of Memory Aging Questionnaire.
ERIC Educational Resources Information Center
Cherry, Katie E.; West, Robin L.; Reese, Celinda M.; Santa Maria, Michael P.; Yassuda, Monica
2000-01-01
The Knowledge of Memory Aging Questionnaire was tested in a group of studies with several populations: 33 mental health professionals; 85 older adults; and 110, 32, and 46 undergraduates. Older adults and professionals knew more about pathological than normal memory aging. Instruction improved undergraduates' pathological knowledge. Instrument…
Equation of state and thermal expansion of metals with FCC structure: Application to Cu, Al and Ni
NASA Astrophysics Data System (ADS)
Tam, Pham Dinh; Hoc, Nguyen Quang; Tinh, Bui Duc; Hien, Nguyen Duc
2014-10-01
The equation of state, the expressions of lattice parameter and thermal expansion coefficient in general form are obtained by the statistical moment method. Applying to Cu, Al and Ni metals, we determine these properties in simple analytic form for each metal. Numerical results for the thermal expansion coefficient of these metals in different temperatures and pressures are in good agreement with experiments.
Technology Transfer Automated Retrieval System (TEKTRAN)
The classical model to describe solute transport in soil is based on the advective-dispersive equation where Fick’s law is used to explain dispersion. From the microscopic point of view this is equivalent to consider that the motion of the particles of solute may be simulated by the Brownian motion....
Presaghi, Fabio; Manca, Maura; Rodriguez-Franco, Luis; Curcio, Giuseppe
2015-01-01
In the last years, intimate partner violence (IPV) became a relevant problem for community and for social life, particularly in young people. Its correct assessment and evaluation in the population is mandatory. Our objectives were: Confirm factor structure of Dating Violence Questionnaire (DVQ) and investigate its convergent and divergent validity. The DVQ along with other personality measures were filled by a sample of 418 university students (Females = 310) of average age of 23 y.o. (SD = 4.71). A subsample of participants (223 students) consented in being involved also in retest and filled also the Revised Eysenck Personality Questionnaire (short form) and a brief scale for describing the behavior of the (past) partner after the breaking of the relationship (BRS). The 8-factor structure, with respect to the two other competing models, reported better fit indexes and showed significant correlations with other personality measures. Personality traits, both Neuroticism and Psychoticism, correlated with Sexual Violence, while Detachment correlated only with Neuroticism and Coercion, Humiliation and Physical Violence correlated with only Psychoticism. Extraversion did not report significant relationships with any of the 8 DVQ factors. Also the predictive validity of DVQ was satisfactory with the partner violent reaction to the break of relationship predicted positively predicted by Coercion (b = 0.22) and by Humiliation (b = 0.20) and negatively by Emotional Punishment (b = -0.18). The present results indicate a good factor structure of the questionnaire, and interesting correlations with personality traits, allowing to identify psychological aspects with a predisposing role for anti-social aggressive behaviors. Further studies will be aimed at ascertaining other possible determinants of intimate partner violence and the weight of cultural aspects. PMID:25992602
A Physical Activity Questionnaire: Reproducibility and Validity
Barbosa, Nicolas; Sanchez, Carlos E.; Vera, Jose A.; Perez, Wilson; Thalabard, Jean-Christophe; Rieu, Michel
2007-01-01
This study evaluates the Quantification de L’Activite Physique en Altitude chez les Enfants (QAPACE) supervised self-administered questionnaire reproducibility and validity on the estimation of the mean daily energy expenditure (DEE) on Bogotá’s schoolchildren. The comprehension was assessed on 324 students, whereas the reproducibility was studied on a different random sample of 162 who were exposed twice to it. Reproducibility was assessed using both the Bland-Altman plot and the intra-class correlation coefficient (ICC). The validity was studied in a sample of 18 girls and 18 boys randomly selected, which completed the test - re-test study. The DEE derived from the questionnaire was compared with the laboratory measurement results of the peak oxygen uptake (Peak VO2) from ergo-spirometry and Leger Test. The reproducibility ICC was 0.96 (95% C.I. 0.95-0.97); by age categories 8-10, 0.94 (0.89-0. 97); 11-13, 0.98 (0.96- 0.99); 14-16, 0.95 (0.91-0.98). The ICC between mean TEE as estimated by the questionnaire and the direct and indirect Peak VO2 was 0.76 (0.66) (p<0.01); by age categories, 8-10, 11-13, and 14-16 were 0.89 (0.87), 0.76 (0.78) and 0.88 (0.80) respectively. The QAPACE questionnaire is reproducible and valid for estimating PA and showed a high correlation with the Peak VO2 uptake. Key pointsThe presence of a supervisor, the limited size of the group with the possibility of answering to their questions could explain the high reproducibility for this questionnaire.No study in the literature had directly addressed the issue of estimating a yearly average PA including school and vacation period.A two step procedure, in the population of schoolchildren of Bogotá, gives confidence in the use of the QAPACE questionnaire in a large epidemiological survey in related populations. PMID:24149485
A Permutation Test for Correlated Errors in Adjacent Questionnaire Items
ERIC Educational Resources Information Center
Hildreth, Laura A.; Genschel, Ulrike; Lorenz, Frederick O.; Lesser, Virginia M.
2013-01-01
Response patterns are of importance to survey researchers because of the insight they provide into the thought processes respondents use to answer survey questions. In this article we propose the use of structural equation modeling to examine response patterns and develop a permutation test to quantify the likelihood of observing a specific…
User questionnaire to evaluate the radiological workspace.
van Ooijen, Peter M A; Koesoema, Allya P; Oudkerk, Matthijs
2006-01-01
Over the past few years, an increase in digitalization of radiology departments can be seen, which has a large impact on the work of the radiologists. This impact is not only demonstrated by the increased use of digital images but also by changing demands on the whole reading environment. In this study, we evaluated the satisfaction of our radiologists with our digital Picture Archival and Communication System environment and their workspace. This evaluation was performed by distribution of a questionnaire consisting of a score sheet and some open questions to all radiologists and residents. Out of 25 questionnaires, 12 were adequately answered and returned. Results clearly showed that most problems were present in the area of reading room design and layout and comfort and ergonomics. Based on the results from this study, adaptations were made and the results were also used in the planning of the redesign of the entire department of radiology. PMID:16767350
Maxwell, Jonathan P
2007-06-01
I developed a Chinese version of the Aggression Questionnaire (Buss & Perry, 1992) by translating scale items into Chinese and subjecting them to standard validation procedures. I used confirmatory factor analysis via structural equation modeling to compare several measurement models. Models based on Buss and Perry's (1992) original four-factor (29-item) scale failed to replicate in the Chinese sample; however, the construct validity of Bryant and Smith's (2001) abridged version of the Aggression Questionnaire received strong overall support. The new 12-item scale demonstrated good fit to the data and adequate internal reliability. Evidence for criterion validity was provided by the scale's sensitivity to differing levels of aggression in males and females. Convergent and discriminant validity received partial support from the pattern of correlations with a measure of anger rumination. Linguistic and metric equivalence were supported by high correlation coefficients between scores on Chinese and English versions of the scale completed by bilingual Chinese on separate occasions. Consistent replications of these preliminary results across three independent samples suggest that the Chinese version of the Aggression Questionnaire may be useful for clinical assessment and cross-cultural research. PMID:17518550