Larsson, G; Larsson, B W; Munck, I M
1998-01-01
In 1994, the questionnaire 'Quality of Care from the Patient's Perspective' (QPP) was developed using a conventional factor analytical approach (Wilde et al. 1994). The items and conceptual framework of this questionnaire were derived from a theoretical model, which, in turn, was developed from qualitative patient interviews, using a grounded theory method of analysis (Wilde et al. 1993). The aims of this study were to develop further the dimensionality of the QPP using structural equation modelling combined with advances in factor analysis modelling, and to refine the instrument. This comparatively new methodology extracts more information out of questionnaire data and is considered to be superior to traditional scaling methods. The sample consisted of 611 somatic inpatients from four departments at a Swedish hospital. Data collected with the QPP were explored with the new tool tracing the dimensions postulated in the theoretical model underlying the QPP. A nested factor model was developed fulfilling statistical criteria for adjustment between model and data. The model consists of a general factor and 16 subordinate factors. Most of the original QPP scales were reproduced with the new statistical technique. However, some content changes were made which appear to bring the QPP scales closer to patients' meaning representations of the area. Some changes were also made to the response format, changes which appear to strengthen the psychometric properties of the instrument. The refined QPP will hopefully contribute to a more differentiated picture of quality of care when applied in the field. All scales, items, and response formats of the revised QPP are presented in an appendix. PMID:9801632
Perera, Harsha N
2015-01-01
Notwithstanding the wide use of the Trait Emotional Intelligence Questionnaire-Short Form (TEIQue-SF) as a brief assessment of trait emotional intelligence (TEI), the psychometric properties of this measure have not been systematically examined. This article reports on research conducted to evaluate the latent structure underlying TEIQue-SF item data and test the gender invariance of scores as critical initial steps in determining the psychometric robustness of the inventory. In doing so, the article demonstrates an application of exploratory structural equation modeling as an alternative to the more restrictive independent clusters model of confirmatory factor analysis for examining factorially complex personality data. On the basis of 476 responses to the TEIQue-SF, evidence was obtained for the multidimensionality of the inventory reflected in a retained correlated traits solution. Tests of gender invariance revealed equivalence of item factor loadings, intercepts, uniquenesses, correlated uniquenesses, and the factor variance-covariance matrix, but not latent means. Men were found to be moderately higher on self-control and sociability than women, whereas women scored marginally higher on emotionality than men. No significant gender differences were found on mean levels of well-being. The benefits of the multidimensionality of the TEIQue-SF, limitations of the study, and directions for future research are discussed. PMID:25774661
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…
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…
Selective Mutism Questionnaire: Measurement Structure and Validity
ERIC Educational Resources Information Center
Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.
2008-01-01
The psychometric properties of the Selective Mutism Questionnaire (SMQ) are evaluated using a clinical sample of children with selective mutism (SM). The study shows that SMQ is useful in determining the severity of a child's nonspeaking behaviors, the scope of these behaviors and necessary follow up assessment.
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…
Revisiting the Factor Structure of the Questionnaire on Smoking Urges
ERIC Educational Resources Information Center
Toll, Benjamin A.; McKee, Sherry A.; Krishnan-Sarin, Suchitra; O'Malley, Stephanie S.
2004-01-01
This study assessed the factor structure of the Questionnaire on Smoking Urges (QSU), a commonly used assessment of cravings for cigarettes, with a sample of smokers presenting for treatment in a smoking cessation trial. On the basis of previous research, three confirmatory factor analytic models were tested. Model 1 hypothesized a 26-item,…
The Infant Crying Questionnaire: initial factor structure and validation.
Haltigan, John D; Leerkes, Esther M; Burney, Regan V; O'Brien, Marion; Supple, Andrew J; Calkins, Susan D
2012-12-01
The current project reports on an initial investigation into the factor structure of the Infant Crying Questionnaire (ICQ), a measure designed to assess parental beliefs about infant crying, in a sample of 259 primiparous mothers. Exploratory factor analyses yielded evidence for a five-factor structure to the ICQ, with two factors that may be conceptually viewed as infant-oriented beliefs regarding infant crying (Attachment/Comfort and Crying as Communication) and three factors conceptually reflecting parent-oriented beliefs regarding infant crying (Minimization, Directive Control, and Spoiling). Each of the scales demonstrated strong internal consistency and was associated with concurrent measures of mothers' causal attributions about emotional responses to infant crying. Predictive validity to observed maternal sensitivity at 6 months and mother-reported infant behavioral problems at one year was demonstrated. The importance of a questionnaire method to assess parents' beliefs regarding infant crying in developmental research is discussed and future methodological directions are outlined. PMID:23007097
Stein, Catherine M; Morris, Nathan J; Nock, Nora L
2012-01-01
Structural equation modeling (SEM) is a multivariate statistical framework that is used to model complex relationships between directly and indirectly observed (latent) variables. SEM is a general framework that involves simultaneously solving systems of linear equations and encompasses other techniques such as regression, factor analysis, path analysis, and latent growth curve modeling. Recently, SEM has gained popularity in the analysis of complex genetic traits because it can be used to better analyze the relationships between correlated variables (traits), to model genes as latent variables as a function of multiple observed genetic variants, and assess the association between multiple genetic variants and multiple correlated phenotypes of interest. Though the general SEM framework only allows for the analysis of independent observations, recent work has extended SEM for the analysis of general pedigrees. Here, we review the theory of SEM for both unrelated and family data, the available software for SEM, and provide an example of SEM analysis. PMID:22307716
Structural equation model trees.
Brandmaier, Andreas M; von Oertzen, Timo; McArdle, John J; Lindenberger, Ulman
2013-03-01
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
The Selective Mutism Questionnaire: Measurement Structure and Validity
Letamendi, Andrea M.; Chavira, Denise A.; Hitchcock, Carla A.; Roesch, Scott C.; Shipon-Blum, Elisa; Stein, Murray B.; Roesch, Scott C.
2010-01-01
Objective To evaluate the factor structure, reliability, and validity of the 17-item Selective Mutism Questionnaire. Method Diagnostic interviews were administered via telephone to 102 parents of children identified with selective mutism (SM) and 43 parents of children without SM from varying U.S. geographic regions. Children were between the ages of 3 and 11 inclusive and comprised 58% girls and 42% boys. SM diagnoses were determined using the Anxiety Disorders Interview Schedule for Children - Parent Version (ADIS-C/P); SM severity was assessed using the 17-item Selective Mutism Questionnaire (SMQ); and behavioral and affective symptoms were assessed using the Child Behavior Checklist (CBCL). An exploratory factor analysis (EFA) was conducted to investigate the dimensionality of the SMQ and a modified parallel analysis procedure was used to confirm EFA results. Internal consistency, construct validity, and incremental validity were also examined. Results The EFA yielded a 13-item solution consisting of three factors: a) Social Situations Outside of School, b) School Situations, and c) Home and Family Situations. Internal consistency of SMQ factors and total scale ranged from moderate to high. Convergent and incremental validity were also well supported. Conclusions Measure structure findings are consistent with the 3-factor solution found in a previous psychometric evaluation of the SMQ. Results also suggest that the SMQ provides useful and unique information in the prediction of SM phenomenon beyond other child anxiety measures. PMID:18698268
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…
Exploratory structural equation modeling of personality data.
Booth, Tom; Hughes, David J
2014-06-01
The current article compares the use of exploratory structural equation modeling (ESEM) as an alternative to confirmatory factor analytic (CFA) models in personality research. We compare model fit, factor distinctiveness, and criterion associations of factors derived from ESEM and CFA models. In Sample 1 (n = 336) participants completed the NEO-FFI, the Trait Emotional Intelligence Questionnaire-Short Form, and the Creative Domains Questionnaire. In Sample 2 (n = 425) participants completed the Big Five Inventory and the depression and anxiety scales of the General Health Questionnaire. ESEM models provided better fit than CFA models, but ESEM solutions did not uniformly meet cutoff criteria for model fit. Factor scores derived from ESEM and CFA models correlated highly (.91 to .99), suggesting the additional factor loadings within the ESEM model add little in defining latent factor content. Lastly, criterion associations of each personality factor in CFA and ESEM models were near identical in both inventories. We provide an example of how ESEM and CFA might be used together in improving personality assessment. PMID:24682748
The Eysenck Personality Questionnaire Brief Version: factor structure and reliability.
Sato, Toru
2005-11-01
The short scale of the Eysenck Personality Questionnaire-Revised (EPQR-S; H. J. Eysenck & S. B. G. Eysenck, 1992) is a 48-item personality questionnaire primarily designed to measure an individual's level of extraversion (vs. introversion) and neuroticism. Although L. J. Francis, L. B. Brown, and R. Philipchalk (1992) created the Eysenck Personality Questionnaire Revised-Abbreviated (EPQR-A), an even briefer version of the EPQR-S, the reliability coefficients of some of the measures have been less than satisfactory (S. Forrest, C. A. Lewis, & M. Shevlin, 2000). Because brevity and reliability are both extremely important, the author of the present study created a briefer version of the EPQR-S, more reliable than the EPQR-A, by making slight alterations in the item content as well as the response format of the EPQR-S. Two hundred and sixty eight participants completed the original EPQR-S and the 24-item newly revised briefer version of the EPQR-S (EPQ-BV) twice. The findings revealed that the EPQ-BV has good internal consistency, test-retest reliability, and concurrent validity. A principal component analysis revealed a solution with factor loadings that accurately reflected the primary measures of the EPQR-S. These findings are discussed in relation to the psychometric properties of the EPQR-A and the original version of the EPQR-S. PMID:16419443
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…
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…
ERIC Educational Resources Information Center
Sun, Huaping; Hernandez, Diley
2012-01-01
This study investigates the structural invariance of the Achievement Goal Questionnaire (AGQ) in American, Chinese, and Dutch college students. Using confirmatory factor analyses (CFA), the authors found evidence for the four-factor structure of achievement goals in all three samples. Subsequent multigroup CFAs supported structural invariance of…
On a Equation in Finite Algebraically Structures
ERIC Educational Resources Information Center
Valcan, Dumitru
2013-01-01
Solving equations in finite algebraically structures (semigroups with identity, groups, rings or fields) many times is not easy. Even the professionals can have trouble in such cases. Therefore, in this paper we proposed to solve in the various finite groups or fields, a binomial equation of the form (1). We specify that this equation has been…
ERIC Educational Resources Information Center
Rast, Philippe; Zimprich, Daniel; Van Boxtel, Martin; Jolles, Jellemer
2009-01-01
The Cognitive Failures Questionnaire (CFQ) is designed to assess a person's proneness to committing cognitive slips and errors in the completion of everyday tasks. Although the CFQ is a widely used instrument, its factor structure remains an issue of scientific debate. The present study used data of a representative sample (N = 1,303, 24-83 years…
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.
2014-01-01
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
Variational structure of the Vlasov equation
Berk, H. L.; Dominguez, R. R.; Maschke, E. K.
1981-03-01
The variational structure of the Vlasov-Maxwell integral equations is derived for a plasma equilibrium having two ignorable coordinates. It is shown that the kernel of the Maxwell equations is a self-adjoint integral operator. This operator may also be represented as a differential equation of arbitrary order. This representation is useful when the differential operator is truncated to finite order, yielding a system of intrinsically self-adjoint differential equations.
Wronskian Structures of Solutions for Soliton Equations
NASA Astrophysics Data System (ADS)
Hirota, R.; Ohta, Y.; Satsuma, J.
Solutions for the equations of the Kadomtsev-Petviashvili hierarchy are given in terms of Wronskian. The two-dimensional Toda lattice equation and the two-dimensional Toda molecule equation are investigated and their solutions are expressed in the form of two-directional Wronskian and double Wronskian. These solutions have common structure so that we can construct systems of these equations and their Wronskian solutions.
Tan, P P; Hawkins, W E
2000-08-01
This study investigated the factor structure of the Minnesota Satisfaction Questionnaire when used by individuals with psychiatric disabilities who are participating in vocational rehabilitation. The sample consisted of 87 respondents recruited from Columbus, Ohio, in 1996 who worked in noncompetitive employment. Factor analyses with varimax rotation conducted on the short-form of the questionnaire indicated three factors, an intrinsic factor and an extrinsic factor (as proposed by the Herzberg two-factor theory) as well as another pertaining to satisfaction derived from participating in vocational rehabilitation. PMID:11026387
Factor structure of the Minnesota Satisfaction Questionnaire short form for restaurant employees.
Hancer, Mura; George, R Thomas
2004-02-01
The factor structure of the Minnesota Satisfaction Questionnaire short form for nonsupervisory restaurant employees was explored in questions among 2000 employees of three full-service restaurant chains operating in midwestern United States. A total of 2000 surveys were distributed to hourly employees of the three chains. From the mailing, 924 surveys were returned and found useable, a 46.2% response rate. Principal factors analysis identified a four-factor structure for the employees, in contrast to the original two-factor structure, but as in other studies the structure was multifactorial. PMID:15077790
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
Gisli H Gudjonsson; Jon F Sigurdsson
1999-01-01
The purpose of this paper was to investigate the factor structure and reliability of the Gudjonsson Confession Questionnaire (GCQ-R) and to investigate its relationship with personality. The GCQ-R measures offenders' reported reasons for confessing to the police and their attitude towards the confession. A total of 411 Icelandic prison inmates and 108 juvenile offenders completed the GCQ-R. A principal component
Oh, Woon Yong; Lee, Ji Woong; Lee, Chong Eon; Ko, Moon Seok; Jeong, Jae Hong
2009-12-01
In this study, a structured survey questionnaire was used to determine consumers' preferences and behavior with regard to horse meat at a horse meat restaurant located in Jeju, Korea, from October 1 to December 24, 2005. The questionnaire employed in this study consisted of 20 questions designed to characterize six general attributes: horse meat sensory property, physical appearance, health condition, origin, price, and other attributes. Of the 1370 questionnaires distributed, 1126 completed questionnaires were retained based on the completeness of the answers, representing an 82.2% response rate. Two issues were investigated that might facilitate the search for ways to improve horse meat production and marketing programs in Korea. The first step was to determine certain important factors, called principal components, which enabled the researchers to understand the needs of horse meat consumers via principal component analysis. The second step was to define consumer segments with regard to their preferences for horse meat, which was accomplished via cluster analysis. The results of the current study showed that health condition, price, origin, and leanness were the most critical physical attributes affecting the preferences of horse meat consumers. Four segments of consumers, with different demands for horse meat attributes, were identified: origin-sensitive consumers, price-sensitive consumers, quality and safety-sensitive consumers, and non-specific consumers. Significant differences existed among segments of consumers in terms of age, nature of work, frequency of consumption, and general level of acceptability of horse meat. PMID:20163664
Bayesian lasso for semiparametric structural equation models.
Guo, Ruixin; Zhu, Hongtu; Chow, Sy-Miin; Ibrahim, Joseph G
2012-06-01
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
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.
Wang, Li; Zhang, Hua; Yuan, Wei-An; Wang, Yi-Xing; Tang, Jie; Cui, Chen; Zeng, Jin; Miao, Ping; Jiang, Jian
2014-11-01
By reviewing research contents of patient-reported outcome (PRO) and discussing Chinese medicine (CM) theories related to chronic liver disease (CLD), we have followed international PRO questionnaire development specification, combined CM theories such as uniformed spirit and body, correspondence between human and the universe, yin in property and yang in function of Gan, and seven emotions, and constructed theoretical structure of PRO questionnaire of treating CLD, including four major areas as physiology, psychology, independence, and society and nature. Of them, the physiological field contained six aspects such as blood deficiency, yin deficiency, bleeding, disorder of qi movement, improper transformation and transportation of Pi-Wei, and abnormal biliary excretion. The psychological field contained two aspects: Gan-related emotions and general disease related emotions. The independence field contained two aspects: daily life and study and work. The field of society and nature contains three aspects: social relations, social environment, and natural adaptability. PMID:25566635
Evaluation of adherence to oral antiviral hepatitis B treatment using structured questionnaires
Giang, Leesa; Selinger, Christian P; Lee, Alice Unah
2012-01-01
AIM: To assess adherence rates to nucleos(t)ide analogues (NUCs) therapy in patients with chronic hepatitis B virus infection and determine factors associated with adherence. METHODS: The questionnaire study was conducted in the liver clinics at Concord Repatriation General Hospital. All patients who were currently taking one or more NUCs were asked to complete a structured, self-administered 32-item questionnaire. Adherence was measured using visual analogue scales. The patient’s treating clinician was also asked to assess their patient’s adherence via a structured questionnaire. RESULTS: A total of 80 patients completed the questionnaire. Sixty six percent of the patients (n = 49) reported optimal adherence whilst 25 (33.8%) graded their adherence to NUCs as suboptimal. Thirty four (43%) patients reported to have omitted taking their NUCs sometime in the past. Recent non-adherence was uncommon. Amongst the patients who reported skipping medications, the most common reason cited was ”forgetfulness“ (n = 27, 56.25%). Other common reasons included: ran out of medications (n = 5, 10.42%), being too busy (n = 4, 8.33%) and due to a change in daily routine (n = 5, 10.42%). Patients who reported low adherence to other prescription pills were also more likely to miss taking NUCs (P = 0.04). Patients who were under the care of a language-discordant clinician were also more likely to report suboptimal adherence to NUCs (P = 0.04). CONCLUSION: Adherence rates were much less than that expected by the physician and has potential adverse affect on long term outcome. Communication and education appear central and strategies need to be implemented to improve ongoing adherence. PMID:22400085
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…
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
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
Multiplicity Control in Structural Equation Modeling
ERIC Educational Resources Information Center
Cribbie, Robert A.
2007-01-01
Researchers conducting structural equation modeling analyses rarely, if ever, control for the inflated probability of Type I errors when evaluating the statistical significance of multiple parameters in a model. In this study, the Type I error control, power and true model rates of famsilywise and false discovery rate controlling procedures were…
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,…
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...
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
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
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
Barron, David; Swami, Viren; Hutchinson, Gerard
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
Factor structure of the Self-Regulation Questionnaire (SRQ) at Spanish universities.
Pichardo, Carmen; Justicia, Fernando; de la Fuente, Jesús; Martínez-Vicente, José Manuel; Berbén, Ana B G
2014-01-01
The Self-Regulation Questionnaire (SRQ) has been used in psychology research during the last decade. The instrument has been used in a variety of life domains: psychological well-being, dispositional happiness, depressive symptoms and career adaptability. This investigation studies the factor structure and internal consistency of the SRQ, extracting a short version in the Spanish context and examining its relation to academic variables (self-regulated learning and grades). The analysis started from a version with 63 items, representing seven conceptual dimensions. This version was administered to a sample of 834 students from Education and Psychology. The data from the above-mentioned sample were randomly divided into two sets, each containing 50% of the students (n = 417): exploratory and confirmatory. In the exploratory sample, exploratory factor analysis findings suggested a more parsimonious measurement model, with 17 items and 4 first-order factors. The confirmatory sample was used in the confirmatory factor analysis. The results show evidence for the internal consistency of the Short Self-Regulation Questionnaire (SSRQ) in the Spanish context, with indices greater than .90 and errors around .05. Regarding academic variables, both versions are related to self-regulated learning (r = .40, p < .01) and students' grades (r = .15, p < .01). Differences from other studies done in North America are discussed, as well as similarities to a study from North-West University (in South Africa). PMID:26054362
Fischer, H Felix; Tritt, Karin; Klapp, Burghard F; Fliege, Herbert
2011-12-01
A wide range of questionnaires for measuring depression are available. Item Response Theory models can help to evaluate the questionnaires exceeding the boundaries of Classical Test Theory and provide an opportunity to equate the questionnaires. In this study after checking for unidimensionality, a General Partial Credit Model was applied to data from two different depression scales [Patient Health Questionnaire (PHQ-9) and ICD-10-Symptom Rating (ISR)] obtained in clinical settings from a consecutive sample, including 4517 observations from a total of 2999 inpatients and outpatients of a psychosomatic clinic. The precision of each questionnaire was compared and the model was used to transform scores based on the assumed underlying latent trait. Both instruments were constructed to measure the same construct and their estimates of depression severity are highly correlated. Our analysis showed that the predicted scores provided by the conversion tables are similar to the observed scores in a validation sample. The PHQ-9 and ISR depression scales measure depression severity across a broad range with similar precision. While the PHQ-9 shows advantages in measuring low or high depression severity, the ISR is more parsimonious and also suitable for clinical purposes. Furthermore, the equation tables derived in this study enhance the comparability of studies using either one of the instruments, but due to substantial statistical spread the comparison of individual scores is imprecise. PMID:22021205
Wording effects and the factor structure of the 12-item General Health Questionnaire (GHQ-12).
Molina, J Gabriel; Rodrigo, Maria F; Losilla, Josep-Maria; Vives, Jaume
2014-09-01
The 12-item version of the General Health Questionnaire (GHQ-12) has become a popular screening instrument with which to measure general psychological health in different settings. Previous studies into the factorial structure of the GHQ-12 have mainly supported multifactor solutions, and only a few recent works have shown that the GHQ-12 was best represented by a single substantive factor when method effects associated with negatively worded items were considered. Confirmatory factor analysis was applied to compare competing measurement models from previous research, including correlated traits-correlated methods and correlated traits-correlated uniquenesses approaches, to obtain further evidence about the factorial structure of the GHQ-12. This goal was achieved with data from 3,050 participants who completed the GHQ-12 included in the Catalonian Survey of Working Conditions (Catalonian Labor Relations and Quality of Work Department, 2012). The results showed additional evidence that the GHQ-12 has a unidimensional structure after controlling for method effects associated with negatively worded items. Furthermore, we found evidence for our hypothesis about the spurious nature of the 3-factor solution in Graetz's (1991) model after comparing its fit with that found for alternative models resulting from different combinations of the negatively worded items. An implication of our results is that future research about the factor structure of the GHQ-12 should take method effects associated with negative wording into account in order to avoid reaching inaccurate conclusions about its dimensionality. PMID:24708077
Moksnes, Unni Karin; Byrne, Don G; Mazanov, Jason; Espnes, Geir Arild
2010-06-01
The present study reports an evaluation of the factor structure of the Norwegian version of the Adolescent Stress Questionnaire (ASQ-N) among 723 students. Principal components analysis (PCA) revealed nine internally consistent dimensions of adolescent stress. Scales constructed from this PCA correlated positively with measures of depression and anxiety and negatively with self-esteem. Girls reported higher stress levels than boys in seven of the nine scales and age was also positively correlated with the scale scores of adolescent stress. The results revealed that the instrument has potential for measuring adolescent stress. The stability of the ASQ-N needs to be tested repeatedly, across cohorts and over time, to establish the adequacy for use in Norwegian adolescent studies. PMID:20149144
Swami, Viren
2009-03-01
The present study examined the factor structure of a Malay translation of the Sociocultural Attitudes Towards Appearance Questionnaire-3 among a community sample of 554 Malaysian women. Results of an exploratory factor analysis revealed the existence of four factors, two of which (Information and Internalization-Athlete) mirrored those found among Western samples. An additional factor was an amalgamation of two factors reported in the West, namely Pressure and Internalization-General. A fourth factor consisted of six items, four of which cross-loaded onto previous factors, and was consequently dropped from analyses. Cronbach's alpha coefficients for the three retained factors were all above .82, and the three factors were significantly correlated with each other and with participants' body mass index. The results of this study stress the need for locally developed scales in the study of body image and a shift away from reliance on scales developed in the West. PMID:19249260
Williams, Matthew J; Dalgleish, Tim; Karl, Anke; Kuyken, Willem
2014-06-01
The five facet mindfulness questionnaire (FFMQ; Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006) and the self-compassion scale (SCS; Neff, 2003) are widely used measures of mindfulness and self-compassion in mindfulness-based intervention research. The psychometric properties of the FFMQ and the SCS need to be independently replicated in community samples and relevant clinical samples to support their use. Our primary aim was to establish the factor structures of the FFMQ and SCS in individuals with recurrent depression in remission, since mindfulness-based cognitive therapy (MBCT) was developed as a treatment for preventing depressive relapse. In order to determine the consistency across populations, we examined the factor structures of the FFMQ and SCS in 3 samples: (1) a convenience sample of adults, (2) a sample of adults who practice meditation, and (3) a sample of adults who suffer from recurrent depression and were recruited to take part in a trial of MBCT. Confirmatory factor analyses (CFAs) showed that a 4-factor hierarchical model of the FFMQ best fits the community sample and the clinical sample but that a 5-factor hierarchical model of the FFMQ best fits the meditator sample. CFA did not endorse the SCS 6-factor hierarchical structure in any of the 3 samples. Clinicians and researchers should be aware of the psychometric properties of the FFMQ to measure mindfulness when comparing meditators and nonmeditators. Further research is needed to develop a more psychometrically robust measure of self-compassion. PMID:24490681
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.
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.…
Structural equation modeling for observational studies
Grace, J.B.
2008-01-01
Structural equation modeling (SEM) represents a framework for developing and evaluating complex hypotheses about systems. This method of data analysis differs from conventional univariate and multivariate approaches familiar to most biologists in several ways. First, SEMs are multiequational and capable of representing a wide array of complex hypotheses about how system components interrelate. Second, models are typically developed based on theoretical knowledge and designed to represent competing hypotheses about the processes responsible for data structure. Third, SEM is conceptually based on the analysis of covariance relations. Most commonly, solutions are obtained using maximum-likelihood solution procedures, although a variety of solution procedures are used, including Bayesian estimation. Numerous extensions give SEM a very high degree of flexibility in dealing with nonnormal data, categorical responses, latent variables, hierarchical structure, multigroup comparisons, nonlinearities, and other complicating factors. Structural equation modeling allows researchers to address a variety of questions about systems, such as how different processes work in concert, how the influences of perturbations cascade through systems, and about the relative importance of different influences. I present 2 example applications of SEM, one involving interactions among lynx (Lynx pardinus), mongooses (Herpestes ichneumon), and rabbits (Oryctolagus cuniculus), and the second involving anuran species richness. Many wildlife ecologists may find SEM useful for understanding how populations function within their environments. Along with the capability of the methodology comes a need for care in the proper application of SEM.
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 of determinants of planning.
Gärling, Tommy; Fujii, Satoshi
2002-02-01
A model is proposed that implies that planning evoked by the formation of an implementation intention is related to behavioral intention and perceived behavioral control, whereas in accordance with the theory of planned behavior, behavioral intention is related to attitude and perceived behavioral control. Measures of attitude toward the behavior, perceived behavioral control, behavioral intention, and planning were constructed from 192 undergraduates' ratings of descriptions of two fictitious situations in which a target behavior was varied with respect to benefit and actual behavioral control. Structural equation modeling yielded an acceptable fit of the proposed model. PMID:11885756
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…
Connolly, Kevin M.; Coffey, Scott F.; Baschnagel, Joseph S.; Drobes, David J.; Saladin, Michael E.
2009-01-01
The current study compared the psychometric properties and clinical/research utility of four distinct factor/subscale models of alcohol craving (three factor-derived models, and one rationally-derived model) as measured by the Alcohol Craving Questionnaire-Now in social (n = 52) and alcohol dependent (n = 71) drinkers. All participants completed a self-report measure of alcohol abuse in addition to engaging in a structured interview and cue reactivity protocol. Participants provided self-reported craving, as well as desire to approach or avoid drinking, during a cue exposure task using separate analogue scales. Factor/subscale models were compared in terms of internal consistency, convergent and divergent validity, and ability to predict cue-elicited approach and craving in addition to diagnostic status. All models demonstrated high levels of internal consistency, convergent and divergent validity, and the ability to predict both cue-elicited craving and alcohol dependence status. Specific strengths and weaknesses of each model are examined and the theoretical, clinical, and research utility of the current findings are discussed. PMID:19423243
Pedrero-Pérez, Eduardo J; Ruiz-Sánchez-de-León, José M; Winpenny-Tejedor, Carmen
2015-12-01
The factorial structure of the Dysexecutive Questionnaire (DEX) is an unresolved issue in scientific literature. One-to-five-factor solutions have been found in several studies by applying different research methods. Only a few of these studies used appropriate analysis procedures to suit a Likert scale-type of answer or investigated large enough samples to ensure the stability of factorial solutions. The present study examines a sample of 2151 subjects, 1482 from the general population and 669 from a clinical population. An unrestricted factorial analysis was carried out on both samples. The results unequivocally point to a single-factor solution in both samples. This means that only one latent variable is displayed in the DEX, which accounts for symptoms of oversight malfunction in activities of daily living. It is concluded that the diversity of results previously obtained in other studies may be due to using research methods that depict Likert-type scales on a continuum when they are actually ordinal categorical measures. In conclusion, the DEX should be considered a screening test that reports symptoms of prefrontal malfunction, although it is unable to specify what areas or functions have been affected, as previous studies have claimed. PMID:25517980
The Hamiltonian structure of discrete KP equations
NASA Astrophysics Data System (ADS)
Kisisel, Ali Ulas Ozgur
2000-12-01
This dissertation contains a study of a two dimensional generalization of Toda equations, introduced by Gieseker in [Gie1]. These are completely integrable differential- difference equations, and are constructed using algebraic geometry. They provide integrable discretizations of the KP equation. We put these systems into Hamiltonian framework by introducing appropriate Poisson brackets. These brackets are non-local, and possess interesting arithmetic and combinatorial properties. One feature that makes them ubiquotious is, they give birth to new brackets for other systems, the examples being periodic band matrix systems that are discussed in [vM-M]. One gets a bi-Hamiltonian interpretation for the band matrix systems by combining the new brackets with the old. The first chapter of the dissertation contains exposition to the material and a collection of relatively well-known results. The second chapter relates discrete KP equations to algebraic geometry. The correspondence between the relevant classes of objects is stated and proven in detail. The third chapter constitutes the core of the thesis. The Poisson brackets that we mentioned are introduced here. The involutivity of the conserved quantities is proven. A bi-Hamiltonian structure for the band matrix systems is gotten. Surprisingly, there seems to be no bi-Hamiltonian interpretation of the discrete KP systems in general. In the end, there is a combinatorial result related to the brackets. The brackets naturally define antisymmetric products on a certain set of objects on the toroidal grid. We call these objects ``toroidal pipe diagrams'' because of their shape. It seems that each of these toroidal pipe diagrams can be interpreted as a 1-cycle on the grid which itself is a discrete torus. Then the product defines an intersection pairing of cycles. This is reminiscent of Goldman and Turaev's intersection pairing on (continuous) surfaces [T], so we guess that there is a link, and this may be an instance of ``discrete'' string topology [C-S].
Self-silencing and depression in women and men: Comparative structural equation models
Kenneth M. Cramer; Melanie D. Gallant; Michelle W. Langlois
2005-01-01
Three personality and sociocultural variables—self-concealment, self-esteem, and masculinity—were evaluated for their role in mediating the relation between self-silencing and depression. There were 825 male and female undergraduates who completed a questionnaire package that included the relevant measures. An analysis of structural equation models supported two hypothesized conceptualizations, each fitting either sex. For females, depression was predicted directly by self-silencing, self-concealment,
Lorrie L. Powel; Jack A. Clark
2005-01-01
In both research and clinical settings, men who survive prostate cancer emphasize the need for more open communication about the challenges they face. They explain that symptomatic dysfunction associated with treatment is grounded in complex social situations and relationships. Yet, structured quality of life questionnaires preclude expressions of the elaborate accounts they often evoke. We explore this in the case
ERIC Educational Resources Information Center
Edwards, Jeffrey R.; O'Neill, Regina M.
1998-01-01
Confirmatory factor analysis was used to evaluate alternative factor structures, based on previous exploratory factor analyses and coping dimensions derived from the theory of R. Lazarus, for the Ways of Coping Questionnaire (S. Folkman and R. Lazarus, 1988). Results from responses of 654 college graduates provide little support for the factor…
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
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…
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.
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. (Bulletin of the Menninger Clinic, 79[3], 232-254). PMID:26366981
2010-01-01
Background Accurate measurement of the components of physical activity during pregnancy can aid in our understanding of the dose response relationships between physical activity and corresponding perinatal outcomes. The aim of this study was to develop and evaluate a one-week recall questionnaire to assess moderate to vigorous physical activity during pregnancy. Methods To assess concurrent-related validity, 177 pregnant women (median 18 weeks' gestation, interquartile range (IQR) 15 -23) kept a structured diary and wore an accelerometer (Actigraph) for one week. At the conclusion of the week, they completed the Pregnancy Infection and Nutrition 3 (PIN3) physical activity questionnaire over the telephone. To assess evidence for test-retest reliability, 109 pregnant women (median 19 weeks' gestation, IQR 18-27) completed the questionnaire twice over the telephone, within 48 hours apart, recalling the same two time periods. Spearman correlation coefficients (SCC) and intraclass correlation coefficients (ICC) were used to assess evidence for validity and reliability, respectively. Results Comparison of the questionnaire to the structured diary was moderate to substantial (SCC 0.47 to 0.69) for several measures of moderate or vigorous physical activity using either perceived or absolute intensity. Comparison of moderate to vigorous physical activity from the questionnaire (absolute intensity using MET-hours/week) to the accelerometer ranged from 0.12 to 0.23 using SCC for absolute intensity (MET-hours/week) and 0.28 to 0.34 using relative intensity (hours/week) (n = 177). Test-retest reliability was moderate to almost perfect for moderate to vigorous physical activity, with the ICC ranging from 0.56 to 0.82 for both perceived and absolute intensities. Conclusions The PIN3 one-week recall questionnaire assessed moderate to vigorous physical activity in the past week with evidence for reliability and validity. PMID:20302668
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
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…
ERIC Educational Resources Information Center
Kim, Sooyeon; Brody, Gene H.; Murry, Velma McBride
2003-01-01
Applied confirmatory factor analysis in a test of alternative factor models and measurement invariance across gender groups, using data from the Early Adolescent Temperament Questionnaire focusing on shyness, high-intensity pleasure, activity level, attention, irritability, and fear. Found that factor models based on composite indicators showed…
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).…
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…
ERIC Educational Resources Information Center
Rudasill, Kathleen Moritz; Foust, Regan Clark; Callahan, Carolyn M.
2007-01-01
Gifted students report that they are often perceived differently than nonidentified students (Cross, Coleman, & Stewart, 1993); thus, they employ social coping strategies to manipulate the visibility of their giftedness. The Social Coping Questionnaire (SCQ; Swiatek, 1995) was designed to assess these strategies. This study's purpose was to…
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…
Suicidal ideation in adolescents: A structural equation modeling approach.
Choi, Jung-Hyun; Yu, Mi; Kim, Kyoung-Eun
2014-06-19
The purpose of this study is to test a model linking adolescents' experience of violence and peer support to their happiness and suicidal ideation. The participants were high school students in Seoul, and in Kyungi, and Chungnam Provinces in Korea. The Conflict Tactics Scale, School Violence Scale, Oxford Happiness Inventory, and Suicidal Ideation Questionnaire were administered to just over 1000 adolescents. The model was tested using a path analysis technique within structural equation modeling. The model fit indices suggest that the revised model is a better fit for the data than the original hypothesized model. The experience of violence had a significant negative direct effect and peer support had a significant positive direct effect on their happiness. Happiness had a significant negative effect and the experience of violence had a significant positive effect on suicidal ideation. These findings demonstrate the fundamental importance of reducing exposure of violence to adolescents, and that increasing peer support and their happiness may be the key to adolescent suicidal ideation prevention. PMID:24943997
A Framework for Structural Equation Models in General Pedigrees
Nathan J. Morris; Robert C. Elston; Catherine M. Stein
2010-01-01
Background\\/Aims: Structural Equation Modeling (SEM) is an analysis approach that accounts for both the causal relationships between variables and the errors associated with the measurement of these variables. In this paper, a framework for implementing structural equation models (SEMs) in family data is proposed. Methods: This framework includes both a latent measurement model and a structural model with covariates. It
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
Fermionic covariant prolongation structure theory for supernonlinear evolution equation
Cheng Jipeng; Wang Shikun; Wu Ke; Zhao Weizhong
2010-09-15
We investigate the superprincipal bundle and its associated superbundle. The super(nonlinear)connection on the superfiber bundle is constructed. Then by means of the connection theory, we establish the fermionic covariant prolongation structure theory of the supernonlinear evolution equation. In this geometry theory, the fermionic covariant fundamental equations determining the prolongation structure are presented. As an example, the supernonlinear Schroedinger equation is analyzed in the framework of this fermionic covariant prolongation structure theory. We obtain its Lax pairs and Baecklund transformation.
Three-Dimensional Structured Networks for Matrix Equation Solving
Li-xin Wang; Jerry M. Mendel
1991-01-01
Two three-dimensional structured networks are developed for solving linear equations and the Lyapunov equation. The basic idea of the structured network approaches is to first represent a given equation-solving problem by a 3-D structured network so that if the network matches a desired pattern array, the weights of the linear neurons give the solution to the problem: then, train the
Dilatonic equation of hydrostatic equilibrium and neutron star structure
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Bordbar, G. H.; Eslam Panah, B.; Najafi, M.
2015-08-01
In this paper, we present a new hydrostatic equilibrium equation related to dilaton gravity. We consider a spherical symmetric metric to obtain the hydrostatic equilibrium equation of stars in 4-dimensions, and generalize TOV equation to the case of regarding a dilaton field. Then, we calculate the structure properties of neutron star using our obtained hydrostatic equilibrium equation employing the modern equations of state of neutron star matter derived from microscopic calculations. We show that the maximum mass of neutron star depends on the parameters of dilaton field and cosmological constant. In other words, by setting the parameters of new hydrostatic equilibrium equation, we calculate the maximum mass of neutron star.
de Minzi, M C; Sacchi, C
2001-02-01
The aim of this work was to examine how the presence of inapplicable items might change the factor structure of the 1984 Ways of Coping Questionnaire by Lazarus and Folkman. The Spanish version of the Ways of Coping Questionnaire was administered to 156 subjects with university degrees. The 95 women and 61 men whose ages were from 18 and 45 years (M = 27.8, SD = 12.1) were of middle socioeconomic status. All were residents of Buenos Aires. To study whether relevant items modify the factor structure of the Ways of Coping Questionnaire, two factor analyses were carried out, one with items rated as not relevant (Item Mean) and the other with the same items rated as not chosen. In both factor analyses, principal axes method and oblimin rotation were performed, and five factors were considered. Congruence indexes were performed. Analysis showed that not choosing an item because it does not coincide with one's behavior or ideas is not the same as not selecting that item because it does not apply to the current threatening situation. Lack of discrimination between situations when analyzing data leads to a distorted interpretation of the way in which the subject actually behaves or copes with the situation. PMID:11293018
Generalized Appended Product Indicator Procedure for Nonlinear Structural Equation Analysis.
ERIC Educational Resources Information Center
Wall, Melanie M.; Amemiya, Yasuo
2001-01-01
Considers the estimation of polynomial structural models and shows a limitation of an existing method. Introduces a new procedure, the generalized appended product indicator procedure, for nonlinear structural equation analysis. Addresses statistical issues associated with the procedure through simulation. (SLD)
Tse, Wai S; Rochelle, Tina L; Cheung, Jacky C K
2011-06-01
The relationship between personality, social functioning, and depression remains unclear. The present study employs structural equation modeling to examine the mediating role of social functioning between harm avoidance (HA), self-directedness (SD), and depression. A sample of 902 individuals completed a self-report questionnaire consisting of the following scales: HA and SD subscales of the Temperament and Character Inventory (TCI), Beck Depression Inventory (BDI), and Social Adaptation Self-Evaluation Scale (SASS). Structural equation modeling via analysis of moment structure was used to estimate the fit of nine related models. Results indicated that social functioning is a mediator between harm avoidance or self-directness and depression. Self-directedness was also shown to have direct effects on depression. The results support the social reinforcement theory of depression and provide a theoretical account of how the variables are related based on correlation methods. Suggestions are offered for future experimental and longitudinal research. PMID:22044236
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…
Two Rules of Identification for Structural Equation Models
ERIC Educational Resources Information Center
Bollen, Kenneth A.; Davis, Walter R.
2009-01-01
Identification of structural equation models remains a challenge to many researchers. Although empirical tests of identification are readily available in structural equation modeling software, these examine local identification and rely on sample estimates of parameters. Rules of identification are available, but do not include all models…
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.
Monge-Rojas, Rafael; Smith-Castro, Vanesa; Colon-Ramos, Uriyoán; Garita-Arce, Carlos; Sánchez-López, Marta; Chinnock, Anne
2010-10-01
This study designed and validated a questionnaire aimed at examining parental feeding styles to encourage healthy eating habits among Costa Rican adolescents. Adolescents (n=133; mean age 15.4 years), and their parents, participated in the study. The parents completed a parental feeding style questionnaire, and the adolescents completed 3-day food records. Confirmatory factor analyses suggest four distinct parental feeding styles, (a) verbal encouragement of healthy eating behaviors; (b) use of verbal sanctions to indirectly control the intake of healthy food; (c) direct control of access to and intake of food; and (d) use of food to regulate emotions and behavior. There were no correlations between dietary intake and the verbal encouragement of healthy eating behaviors, but there were significant negative correlations between (1) "the use of verbal sanctions to indirectly control the intake of healthy food", and the consumption of fruit and vegetable, of calcium, iron, vitamin B6 and folic acid intake, and (2) between the "direct control of access to and intake of food" and fast food consumption and total carbohydrates intake. The use of food to regulate emotions and behavior was positively correlated with high energy-dense food consumption. Stratification of the data shows significant differences by gender in the correlations between parental feeding style and dietary intake. Understanding parental feeding styles in a Latin American context is a first step in helping researchers develops culturally-appropriate parenting intervention/prevention strategies to encourage healthy eating behaviors during adolescence. PMID:20600415
ERIC Educational Resources Information Center
Piedmont, Ralph L.; Sherman, Martin F.; Sherman, Nancy C.; Williams, Joseph E. G.
2003-01-01
This study examined the psychometrics of the Structured Clinical Interview for DSM-IV Personality Disorders Personality Questionnaire (SCID-IIP) self-report personality questionnaire. The responses to the instrument were found reliable and evidenced good self-other convergence. Correlations with external criteria showed the SCID-IIP to contain…
Validating a tourism development theory with structural equation modeling
Yooshik Yoon; Dogan Gursoy; Joseph S. Chen
2001-01-01
This study attempts to examine the structural effects of four tourism-impact factors on total impact and on local residents’ support for tourism development. To achieve the above goal, five research hypotheses are proposed. Three hundred and four questionnaires from a mail survey of randomly selected residents from the Norfolk\\/Virginia Beach\\/Newport News area were analyzed. A confirmatory factor analysis and structural
Critical Factors Analysis for Offshore Software Development Success by Structural Equation Modeling
NASA Astrophysics Data System (ADS)
Wada, Yoshihisa; Tsuji, Hiroshi
In order to analyze the success/failure factors in offshore software development service by the structural equation modeling, this paper proposes to follow two approaches together; domain knowledge based heuristic analysis and factor analysis based rational analysis. The former works for generating and verifying of hypothesis to find factors and causalities. The latter works for verifying factors introduced by theory to build the model without heuristics. Following the proposed combined approaches for the responses from skilled project managers of the questionnaire, this paper found that the vendor property has high causality for the success compared to software property and project property.
New Formulation of the Governing Equations for Analyzing Outrigger Structures
NASA Astrophysics Data System (ADS)
Er, Guo-Kang
2010-05-01
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.
Evaluating the Internal Structure of the Eysenck Personality Questionnaire: Objective Criteria.
ERIC Educational Resources Information Center
Helmes, Edward
1989-01-01
Objective criteria for evaluating the Eysenck Personality Inventory's internal structure are discussed. An approach based on targeted rotations and the test's scoring key is proposed as a means of providing common criteria. Data from earlier structure and test results for 195 undergraduates support the utility of 3 criteria developed. (SLD)
USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES
This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...
A general non-linear multilevel structural equation mixture model
Kelava, Augustin; Brandt, Holger
2014-01-01
In the past 2 decades latent variable modeling has become a standard tool in the social sciences. In the same time period, traditional linear structural equation models have been extended to include non-linear interaction and quadratic effects (e.g., Klein and Moosbrugger, 2000), and multilevel modeling (Rabe-Hesketh et al., 2004). We present a general non-linear multilevel structural equation mixture model (GNM-SEMM) that combines recent semiparametric non-linear structural equation models (Kelava and Nagengast, 2012; Kelava et al., 2014) with multilevel structural equation mixture models (Muthén and Asparouhov, 2009) for clustered and non-normally distributed data. The proposed approach allows for semiparametric relationships at the within and at the between levels. We present examples from the educational science to illustrate different submodels from the general framework. PMID:25101022
Fit Index Sensitivity in Multilevel Structural Equation Modeling
Boulton, Aaron Jacob
2011-07-29
Multilevel Structural Equation Modeling (MSEM) is used to estimate latent variable models in the presence of multilevel data. A key feature of MSEM is its ability to quantify the extent to which a hypothesized model fits the observed data. Several...
Darcy, Alison M; Hardy, Kristina K; Crosby, Ross D; Lock, James; Peebles, Rebecka
2013-06-01
The study explored the psychometric properties of the Eating Disorder Examination Questionnaire (EDE-Q) among 1637 university students. Participants were divided into male (n=432) and female (n=544) competitive athletes, and male (n=229) and female (n=429) comparison groups comprised of individuals who had not engaged in competitive sports for at least one year. All groups were subjected to confirmatory factor analysis (CFA) to test the fit of the published factor structure in this population, and then exploratory FA (EFA). A three-factor solution was the best fit for three out of four groups, with a two-factor solution providing best fit for the male comparison group. The first factor for all groups resembled a combined Shape and Weight Concern subscale. The factor structure among male and female competitive athletes was remarkably similar; however, non-competitive athletic/low activity males appear qualitatively different from other groups. PMID:23453695
The structural equations of Cartan and the wave solution Einstein's equation
Shcherban, Vladimir
2008-01-01
Work consists of introduction, two chapters, conclusion and four applications. In this work is examined the condition, with which the wave space metrics of Riemann- Cartan is the solution of Einstein equation in the void. Geometric structures were for this purpose studied on the differentiated variety: connectedness, curvature and twisting connectedness. For this was used this analytical apparatus of differential geometry as the calculation of exterior forms. In the first chapter the following concepts are examined: - variety; - vectors and 1- forms on the varieties; - metric tensor, connectedness and the covariant derivative; - form with the values in the vector spaces; - the structural equations of Cartan. The second chapter is dedicated to the presence of condition, during which wave certificate is the solution of Einstein equation in the void. Using the first and second structural equations of Cartan for the variety without twisting of that allotted by wave certificate, they were calculated: the 1- forms ...
On the structure of the exact master equation
Ines de Vega
2014-03-31
We derive a master equation from the exact stochastic Liouville von-Neumann (SLN) equation \\cite{stockburger2002,wallsbook}. 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 \\cite{koch2008,koch2010}.
Analytic structure of solutions to multiconfiguration equations
NASA Astrophysics Data System (ADS)
Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas; Sørensen, Thomas Østergaard
2009-08-01
We study the regularity at the positions of the (fixed) nuclei of solutions to (non-relativistic) multiconfiguration equations (including Hartree-Fock) of Coulomb systems. We prove the following: let {phiv1, ..., phivM} be any solution to the rank-M multiconfiguration equations for a molecule with L fixed nuclei at R_1,\\ldots,R_L\\in{\\bb R}^3 . Then, for any j in {1, ..., M}, k in {1, ..., L}, there exists a neighborhood U_{j,k}\\subseteq{\\bb R}^3 of Rk, and functions phiv(1)j,k, phiv(2)j,k, real analytic in Uj,k, such that \\vphantom{\\frac12}\\varphi_j(\\mathbf{x})=\\varphi^{(1)}_{j,k}(\\mathbf{x}) +|\\mathbf{x}-R_k|\\varphi^{(2)}_{j,k}(\\mathbf{x}),\\qquad {\\bf x}\\in U_{j,k}. A similar result holds for the corresponding electron density. The proof uses the Kustaanheimo-Stiefel transformation, as applied in [9] to the study of the eigenfunctions of the Schrödinger operator of atoms and molecules near two-particle coalescence points.
Freshman Academic Achievement: A Structural Equation Model.
ERIC Educational Resources Information Center
Zhang, Zhicheng; RiCharde, R. Stephen
The causal structure between academic achievement and cognitive, psychological, and facilitative variables during the freshman year in college was studied. Data from 455 freshmen were used in the analysis. Participants completed measures of student goals, facilitative skills, and learning and thinking styles. Pre-college and freshman achievement…
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…
Hill, Ryan M; Rey, Yasmin; Marin, Carla E; Sharp, Carla; Green, Kelly L; Pettit, Jeremy W
2015-06-01
Five versions of the Interpersonal Needs Questionnaire (INQ), a self-report measure of perceived burdensomeness and thwarted belongingness, have been used in recent studies (including 10-, 12-, 15-, 18-, and 25-items). Findings regarding the associations between perceived burdensomeness, thwarted belongingness, and suicidal ideation using different versions have been mixed, potentially due to differences in measurement scales. This study evaluated factor structure, internal consistency, and concurrent predictive validity of these five versions in three samples. Samples 1 and 2 were comprised of 449 and 218 undergraduates, respectively; Sample 3 included 114 adolescent psychiatric inpatients. All versions demonstrated acceptable internal consistency. The 10-item version and 15-item version demonstrated the best, most consistent model fit in confirmatory factor analyses. Both perceived burdensomeness and thwarted belongingness consistently predicted concurrent suicidal ideation on the 10-item INQ only. Future research should consider using the 15-item or 10-item versions. PMID:25308815
Molero Alonso, Fernando; Recio Saboya, Patricia; Cuadrado Guirado, Isabel
2010-08-01
The Multifactor Leadership Questionnaire (MLQ) has been one of the most commonly used instruments to assess leadership in organizational settings for the last two decades. However, the factor structure proposed by the MLQ authors has received some criticism. The aim of this work is to examine the fit indices of several alternative factor models suggested by the literature. In order to accomplish this objective, we conducted confirmatory factor analyses in a sample of 954 participants using a Spanish version of the MLQ. Results show that the model that produces the better fit with the data consists of four factors: transformational leadership, developmental/transactional leadership, corrective leadership and avoidant/passive leadership. This model is parsimonious and consistent with the MLQ literature. PMID:20667281
Generalized Appended Product Indicator Procedure for Nonlinear Structural Equation Analysis
Melanie M. Wall; Yasuo Amemiya
2001-01-01
Interest in considering nonlinear structural equation models is well documented in the behavioral and social sciences as well as in the education and marketing literature. This article considers estimation of polynomial structural models. An existing method is shown to have a limitation that the produced estimator is inconsistent for most practical situations. A new procedure is introduced and defined for
Structural equation modelling and regression analysis in tourism research
Robin Nunkoo; Haywantee Ramkissoon
2011-01-01
This paper explores the concept of structural equation modelling (SEM) and discusses the steps which researchers should follow when using this technique. This involves the development of a theoretical model, testing of a confirmatory measurement model, and evaluating the structural model with hypothesised path relations. For the benefit of readers, the discussion is supported by an illustration of a theoretical
Structural Equation Modeling in the Communication Sciences, 1995-2000.
ERIC Educational Resources Information Center
Holbert, R. Lance; Stephenson, Michael T.
2002-01-01
Notes that structural equation modeling (SEM) is a viable multivariate tool used by communication researchers for the past quarter century. Summarizes the use of this technique from 1995-2000 in 37 communication-based academic journals. Identifies and critically assesses 3 unique methods for testing structural relationships via SEM in terms of the…
On Nonequivalence of Several Procedures of Structural Equation Modeling
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Chan, Wai
2005-01-01
The normal theory based maximum likelihood procedure is widely used in structural equation modeling. Three alternatives are: the normal theory based generalized least squares, the normal theory based iteratively reweighted least squares, and the asymptotically distribution-free procedure. When data are normally distributed and the model structure…
Examining the cognitive model of caregiving--a structural equation modelling approach.
Hesse, Klaus; Klingberg, Stefan
2014-07-30
The study tests assumptions from the "cognitive model of caregiving" (Kuipers et al., 2010), which aims to inform interventions for carers of people with psychoses. The sample comprised 61 relatives of patients with schizophrenia. Standardized psychological assessments were conducted twice within 6 months including Involvement Evaluation Questionnaire (IEQ-EU), a short form of the Symptom Checklist 90-R (SCL K9), the Family Questionnaire (FQ), scales measuring control attributions of the Illness Perception Questionnaire for Schizophrenia (IPQS-R) and emotions toward the ill relative. Structural equation modelling was used to analyse data. We identified two pathways: (a) from "attributing control to relatives" to distress, intermediated by anxiety for the patient and emotional overinvolvement (EOI), and (b) from "attribution control to patient" to distress, intermediated by anger about the patient and criticism. The model provided a good fit to the data and was successfully replicated at a second point in time. We were able to find supporting evidence for a cognitive model of caregiving. Control attributions and emotions of informal caregivers are important when interventions are planned reducing expressed emotion and burden of caregivers. PMID:24740133
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
Cecchini, Jose A; Fernández-Rio, Javier; Méndez-Giménez, Antonio
2015-06-27
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
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…
Miranda, Ana; Grau, Dolores; Rosel, Jesús; Meliá, Amanda
2009-11-01
One hundred and fifty-five mothers of children with attention deficit/hyperactivity disorder (ADHD) completed a semi-structured interview, the Parenting Stress Index Questionnaire (Abidin, 1990), to evaluate parenting stress. The Parenting Scale (Arnold, O'Leary, Wolff & Acker, 1993) was also administered to measure dysfunctional discipline strategies. Structural equation modeling was used to test a model in which the independent variables were the Child's Characteristics and the Socio-Educational Status of his or her family; intermediate variables were Parenting Stress concerning the Child Domain and concerning the Parent Domain; and the dependent variable was Parental Discipline. The results confirm our hypotheses. Interventions in these families should therefore incorporate a component focused on Parenting Stress (in both the Child Domain and the Parent Domain), as a determinant of Parental Discipline. PMID:19899651
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
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.
Robust Structural Equation Modeling with Missing Data and Auxiliary Variables
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Zhang, Zhiyong
2012-01-01
The paper develops a two-stage robust procedure for structural equation modeling (SEM) and an R package "rsem" to facilitate the use of the procedure by applied researchers. In the first stage, M-estimates of the saturated mean vector and covariance matrix of all variables are obtained. Those corresponding to the substantive variables are then…
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…
Analyzing Mixed-Dyadic Data Using Structural Equation Models
ERIC Educational Resources Information Center
Peugh, James L.; DiLillo, David; Panuzio, Jillian
2013-01-01
Mixed-dyadic data, collected from distinguishable (nonexchangeable) or indistinguishable (exchangeable) dyads, require statistical analysis techniques that model the variation within dyads and between dyads appropriately. The purpose of this article is to provide a tutorial for performing structural equation modeling analyses of cross-sectional…
Model Comparison of Nonlinear Structural Equation Models with Fixed Covariates.
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan
2003-01-01
Proposed a new nonlinear structural equation model with fixed covariates to deal with some complicated substantive theory and developed a Bayesian path sampling procedure for model comparison. Illustrated the approach with an illustrative example using data from an international study. (SLD)
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…
Testable Implications of Linear Structural Equation Models Bryant Chen
California at Los Angeles, University of
structural equation model (SEM) rely on the likelihood ra- tio or chi-square test which simultaneously tests ratio or chi-square test that compares the covariance matrix implied by the model that a global chi-square test Copyright c 2014, Association for the Advancement of Artificial Intelligence (www
Testable Implications of Linear Structural Equation Models Bryant Chen
Tian, Jin
structural equation model (SEM) rely on the likelihood ratio or chi-square test which simulta- neously tests of testing a model is a likelihood ratio or chi-square test that compares the covariance matrix implied is very large and complex, it is possible that a global chi-square test will not reject the model even
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…
Evaluating Interventions with Multimethod Data: A Structural Equation Modeling Approach
ERIC Educational Resources Information Center
Crayen, Claudia; Geiser, Christian; Scheithauer, Herbert; Eid, Michael
2011-01-01
In many intervention and evaluation studies, outcome variables are assessed using a multimethod approach comparing multiple groups over time. In this article, we show how evaluation data obtained from a complex multitrait-multimethod-multioccasion-multigroup design can be analyzed with structural equation models. In particular, we show how the…
CSS Equation, etc, Follow from Structure of TMD Factorization
John Collins
2012-12-24
I show that the forms of the Collins-Soper-Sterman and renormalization-group equations for the evolution of transverse-momentum-dependent (TMD) parton densities in QCD follow from the structure of TMD factorization. A derivation does not need to directly use detailed properties of the operator definition of the TMD parton densities.
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…
Principles and practice in reporting structural equation analyses
Roderick P. McDonald; Moon-Ho Ringo Ho
2002-01-01
Principles for reporting analyses using structural equation modeling are reviewed, with the goal of supplying readers with complete and accurate information. It is recommended that every report give a detailed justification of the model used, along with plausible alternatives and an account of identifiability. Nonnormality and missing data problems should also be addressed. A complete set of parameters and their
Play Context, Commitment, and Dating Violence: A Structural Equation Model
ERIC Educational Resources Information Center
Gonzalez-Mendez, Rosaura; Hernandez-Cabrera, Juan Andres
2009-01-01
This study develops a structural equation model to describe the effect of two groups of factors (type of commitment and play context) on the violence experienced during intimate partner conflict. After contrasting the model in adolescents and university students, we have confirmed that aggressive play and the simulation of jealousy and anger…
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…
Bayesian Analysis of Structural Equation Model with Fixed Covariates.
ERIC Educational Resources Information Center
Lee, Sik-Yum; Shi, Jian-Qing
2000-01-01
Extends the LISREL model to incorporate fixed covariates at both the measurement and the structural equations of the model, establishing a Bayesian procedure with conjugate type prior distributions. Illustrates the efficiency of the algorithm and presents a goodness of fit statistic for assessing the proposed model. (SLD)
The General Linear Model as Structural Equation Modeling
ERIC Educational Resources Information Center
Graham, James M.
2008-01-01
Statistical procedures based on the general linear model (GLM) share much in common with one another, both conceptually and practically. The use of structural equation modeling path diagrams as tools for teaching the GLM as a body of connected statistical procedures is presented. A heuristic data set is used to demonstrate a variety of univariate…
Multiplicity Control in Structural Equation Modeling: Incorporating Parameter Dependencies
ERIC Educational Resources Information Center
Smith, Carrie E.; Cribbie, Robert A.
2013-01-01
When structural equation modeling (SEM) analyses are conducted, significance tests for all important model relationships (parameters including factor loadings, covariances, etc.) are typically conducted at a specified nominal Type I error rate ([alpha]). Despite the fact that many significance tests are often conducted in SEM, rarely is…
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
Peculiar symmetry structure of some known discrete nonautonomous equations
NASA Astrophysics Data System (ADS)
Garifullin, R. N.; Habibullin, I. T.; Yamilov, R. I.
2015-06-01
We study the generalized symmetry structure of three known discrete nonautonomous equations. One of them is the semidiscrete dressing chain of Shabat. Two others are completely discrete equations defined on the square lattice. The first one is a discrete analogue of the dressing chain introduced by Levi and Yamilov. The second one is a nonautonomous generalization of the potential discrete KdV equation or, in other words, the H1 equation of the well-known Adler?Bobenko?Suris list. We demonstrate that these equations have generalized symmetries in both directions if and only if their coefficients, depending on the discrete variables, are periodic. The order of the simplest generalized symmetry in at least one direction depends on the period and may be arbitrarily high. We substantiate this picture by some theorems in the case of small periods. In case of an arbitrarily large period, we show that it is possible to construct two hierarchies of generalized symmetries and conservation laws. The same picture should take place in case of any nonautonomous equation of the Adler?Bobenko?Suris list.
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…
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…
Tian P. S. Oei; Penelope A. Hasking; Ross Mc D. Young
2005-01-01
The drinking refusal self-efficacy questionnaire (DRSEQ: Young, R.M., Oei, T.P.S., 1996. Drinking expectancy profile: test manual. Behaviour Research and Therapy Centre, University of Queensland, Australia; Young, R.M., Oei, T.P.S., Crook, G.M., 1991. Development of a drinking refusal self-efficacy questionnaire. J. Psychopathol. Behav. Assess., 13, 1–15) assesses a person's belief in their ability to resist alcohol. The DRSEQ is a sound
Development and validation of a weight-related eating questionnaire.
Schembre, Susan; Greene, Geoffrey; Melanson, Kathleen
2009-04-01
The objective of this study was to develop an improved weight-related eating questionnaire (WREQ) that reflects recent advancements in the assessment and understanding of theory-based eating behaviors. A sequential process of measurement development was used to construct this brief but comprehensive questionnaire. By factor analysis and structural equation modeling, a 16-item, four-factor structure was found to best fit the data. This newly developed questionnaire measures two constructs of dietary restraint (routine and compensatory restraint), susceptibility to external cues (external eating), and emotional eating. The WREQ demonstrated good preliminary construct validation against similar psychometrics, BMI, and measures of fruit and vegetable and dietary fat intake. Further validation analyses, particularly against other energy intake measures, are justified. Successful development and preliminary validation of this updated weight-related eating behavior questionnaire provides support for the WREQ as an improvement over existing eating behavior measures and warrants its use in future research. PMID:19447354
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.
ERIC Educational Resources Information Center
Raykov, Tenko; Shrout, Patrick E.
2002-01-01
Discusses a method for obtaining point and interval estimates of reliability for composites of measures with a general structure. The approach is based on fitting a correspondingly constrained structural equation model and generalizes earlier covariance structure analysis methods for scale reliability estimation with congeneric tests. (SLD)
Religion, Forgiveness, Hostility and Health: A Structural Equation Analysis
Laura J. Lutjen; Nava R. Silton; Kevin J. Flannelly
Religious participation has been shown to increase certain factors thought to be protective of health, including social support\\u000a and positive health habits. The current study considers whether religious participation may likewise have a positive influence\\u000a on health by increasing forgiveness and diminishing hostility. A structural equation analysis of data collected from a national\\u000a survey of 1,629 participants supported the hypothesized
Universal structure and universal equations (PDE) for unitary ensembles
NASA Astrophysics Data System (ADS)
Rumanov, Igor
2010-08-01
Random matrix ensembles with unitary invariance of measure (UE) are described in a unified way using a combination of Tracy-Widom (TW) and Adler-Shiota-van Moerbeke approaches to the derivation of partial differential equations (PDEs) for spectral gap probabilities. First, general three-term recurrence relations for UE restricted to subsets of real line, or, in other words, for functions in the resolvent kernel, are obtained. Using them, simple universal relations between all TW dependent variables and one-dimensional Toda lattice ?-functions are found. A universal system of PDE for UE is derived from previous relations, which leads also to a single independent PDE for spectral gap probability of various UE. Thus, orthogonal function bases and Toda lattice are seen at the core of correspondence of different approaches. Moreover, Toda-AKNS system provides a common structure of PDE for unitary ensembles. Interestingly, this structure can be seen in two very different forms: one arises from orthogonal function-Toda lattice considerations, while the other comes from Schlesinger equations for isomonodromic deformations and their relation to TW equations. The simple example of Gaussian matrices most neatly exposes this structure.
The local Callan-Symanzik equation: structure and applications
Florent Baume; Boaz Keren-Zur; Riccardo Rattazzi; Lorenzo Vitale
2014-12-03
The local Callan-Symanzik equation describes the response of a quantum field theory to local scale transformations in the presence of background sources. The consistency conditions associated with this anomalous equation imply non-trivial relations among the $\\beta$-function, the anomalous dimensions of composite operators and the short distance singularities of correlators. In this paper we discuss various aspects of the local Callan-Symanzik equation and present new results regarding the structure of its anomaly. We then use the equation to systematically write the n-point correlators involving the trace of the energy-momentum tensor. We use the latter result to give a fully detailed proof that the UV and IR asymptotics in a neighbourhood of a 4D CFT must also correspond to CFTs. We also clarify the relation between the matrix entering the gradient flow formula for the $\\beta$-function and a manifestly positive metric in coupling space associated with matrix elements of the trace of the energy momentum tensor.
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.
Structural Stability of the Coalescence/Breakup Equation.
NASA Astrophysics Data System (ADS)
Brown, Philip S., Jr.
1995-11-01
An analysis of the structural stability of the coalescence/breakup equation is performed to determine the degree to which changes in the equation's formulation can affect the solution. The work was motivated by speculation in various quarters that the currently used coalescence/breakup formulation should be adjusted to achieve better agreement between solutions and field observations. Both analytical procedures and numerical experiments, in which hypothetical changes in the rate coefficients are assumed, show the coalescence/breakup equation in its current formulation to be structurally stable. Not only do small changes in the rate coefficients produce negligible change in the solutions, but even large changes in the rate coefficients fail to destroy the fundamental behavior of the system in that all solutions continue to approach a unique equilibrium. Moderate-sized perturbations of the coefficients are found to have only minor influence on the solutions unless the coalescence and breakup efficiencies, constituents of the rate coefficients, are perturbed in an opposite sense to reinforce the individual effects. Only with such changes in the formulation is the equilibrium solution found to be altered to a significant degree.
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
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.,…
ERIC Educational Resources Information Center
McCormick, Ernest J.
The Position Analysis Questionnaire (PAQ) is a job analysis instrument consisting of 187 job elements organized into six divisions. The PAQ was used in the eight studies summarized in this final report. The studies were: (1) ratings of the attribute requirements of PAQ job elements, (2) a series of principal components analyses of these attribute…
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
Olivier Luminet; Cecile Leroy; Emmanuel Roy
2007-01-01
In this research, we investigated the psychometrical properties of the Trait Emotional Intelligence Questionnaire (TEIQue, Petrides & Furnham, 2003) in a French-speaking population. In summary, we found that (a) TEIQue scores were globally normally distributed and reliable; (b) the United Kingdom four-factor structure (well-being, self-control, emotionality, sociability) replicated in our data; (c) TEIQue scores were dependent on gender but relatively
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
a105 ?Chapter9?Little? ? 2007/2/12 ? 15:58 ? page 207 ? #1 a105 a105 a105 a105 a105 CHAPTER NINE Structural Equation Modeling of Mediation and Moderation With Contextual Factors Todd D. Little University of Kansas Noel A. Card University of Arizona... relationships are de- scribed in terms such as indirect influences, distal vs. proximal causes, interme- diate outcomes, and ultimate causes; all of which share the concept of mediation. Similarly, researchers must often consider that an observed relationship...
Introduction to the special section on structural equation modeling.
Tomarken, Andrew J; Baker, Timothy B
2003-11-01
Structural equation modeling (SEM) is a frequently used data-analytic technique in psychopathology research. This popularity is due to the unique capabilities and broad applicability of SEM and to recent advances in model and software development. Unfortunately, the popularity and accessibility of SEM is matched by its complexities and ambiguities. Thus, users are often faced with difficult decisions regarding a variety of issues. This special section is designed to increase the effective use of SEM by reviewing recently developed modeling capabilities, identifying common problems in application, and recommending appropriate strategies for analysis and evaluation. PMID:14674866
Predicting Overall Service Quality. A Structural Equation Modelling Approach
Carme Saurina; Germà Coenders
In this article, the results of a modified SERVQUAL questionnaire (Parasuraman et al., 1991) are reported. The modifications consisted in substituting questionnaire items particularly suited to a specific service (banking) and context (county of Girona, Spain) for the original rather general and abstract items. These modifications led to more interpretable factors which accounted for a higher percentage of item variance.
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.
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.
The Interface Between Theory and Data in Structural Equation Models
Grace, James B.; Bollen, Kenneth A.
2006-01-01
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, for representing general concepts. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling general relationships 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 influences of suites of variables are often of interest.
Questionnaire Development Resources
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.
NASA Astrophysics Data System (ADS)
Stalin, S.; Senthilvelan, M.
2011-10-01
In this Letter, we formulate an exterior differential system for the newly discovered cubically nonlinear integrable Camassa-Holm type equation. From the exterior differential system we establish the integrability of this equation. We then study Cartan prolongation structure of this equation. We also discuss the method of identifying conservation laws and Bäcklund transformation for this equation from the identified exterior differential system.
Bayesian Analysis of Structural Equation Models with Nonlinear Covariates and Latent Variables
ERIC Educational Resources Information Center
Song, Xin-Yuan; Lee, Sik-Yum
2006-01-01
In this article, we formulate a nonlinear structural equation model (SEM) that can accommodate covariates in the measurement equation and nonlinear terms of covariates and exogenous latent variables in the structural equation. The covariates can come from continuous or discrete distributions. A Bayesian approach is developed to analyze the…
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.
Structural equation modeling in medical research: a primer
2010-01-01
Background Structural equation modeling (SEM) is a set of statistical techniques used to measure and analyze the relationships of observed and latent variables. Similar but more powerful than regression analyses, it examines linear causal relationships among variables, while simultaneously accounting for measurement error. The purpose of the present paper is to explicate SEM to medical and health sciences researchers and exemplify their application. Findings To facilitate its use we provide a series of steps for applying SEM to research problems. We then present three examples of how SEM has been utilized in medical and health sciences research. Conclusion When many considerations are given to research planning, SEM can provide a new perspective on analyzing data and potential for advancing research in medical and health sciences. PMID:20969789
Shock wave structure using nonlinear model Boltzmann equations
NASA Technical Reports Server (NTRS)
Segal, Ben Maurice
1971-01-01
The structure of a strong plane shock wave in a monatomic rarefied perfect gas is one of the simplest problems able to be posed in kinetic theory, and one of the hardest to solve. Its simplicity lies in the absence of solid boundaries, geometrical complications, or internal molecular energy. Its difficulty arises from the great departure of the gas from equilibrium within the shock, which invalidates many of the techniques used successfully elsewhere in kinetic theory. In addition to this theoretical challenge, the modern development of ballistics and hypersonic flight has helped to stimulate extensive theoretical and experimental interest in the shock problem. The experimenters in turn have encountered great difficulties on account of the very small physical dimensions of shocks. In fact, until very recently indeed, any close comparisons of theoretical and experimental shock structure results have been rather unprofitable due to the inadequacies of both theory and experiment. During the last few years this situation has been appreciably improved by development of the Monte Carlo method. This allows idealized 'experiments' to be performed on large computers instead of in wind tunnels, using a known intermolecular force law. The most developed of these methods has been shown to be equivalent theoretically to the Boltzmann equation and to give results which agree extremely closely with measurements of high accuracy. Thus Monte Carlo results not only form the soundest basis for our present theoretical knowledge of shock wave structure, but, for purposes of developing other theories, can also be considered a very valuable experimental resource. However, such results remain very expensive to obtain. In this thesis we develop more economical kinetic theory methods for the approximate prediction of shock structure, and compare our results with those of the Monte Carlo method.
Anxiety, Depression and Hopelessness in Adolescents: A Structural Equation Model
Cunningham, Shaylyn; Gunn, Thelma; Alladin, Assen; Cawthorpe, David
2008-01-01
Objective This study tested a structural model, examining the relationship between a latent variable termed demoralization and measured variables (anxiety, depression and hopelessness) in a community sample of Canadian youth. Methods The combined sample consisted of data collected from four independent studies from 2001 to 2005. Nine hundred and seventy one (n=971) participants were high school students (grades 10–12) from three geographic locations: Calgary, Saskatchewan and Lethbridge. Participants completed the Beck Anxiety Inventory (BAI), Beck Depression Inventory-Revised (BDI-II), Beck Hopelessness Scale (BHS), and demographic survey. Structural equation modeling was used for statistical analysis. Results The analysis revealed that the final model, including depression, anxiety and hopelessness and one latent variable demoralization, fit the data (chi-square value, X2 (2) = 7.25, p< .001, goodness of fit indices (CFI=0.99, NFI=0.98) and standardized error (0.05). Overall, the findings suggest that close relationships exist among depression, anxiety, hopelessness and demoralization that is stable across demographic variables. Further, the model explains the relationship between sub-clinical anxiety, depression and hopelessness. Conclusion These findings contribute to a theoretical framework, which has implications for educational and clinical intervention. The present findings will help guide further preventative research on examining demoralization as a precursor to sub-clinical anxiety and depression. PMID:18769644
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.
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.
NASA Astrophysics Data System (ADS)
Ab Hamid, Mohd Rashid; Mustafa, Zainol; Mohd Suradi, Nur Riza; Idris, Fazli; Abdullah, Mokhtar
2013-04-01
Culture and employee-focused criteria are important factors for the success of any organization. These factors have to be aligned with the productivity initiatives in the organization in order to gear ahead for excellence. Therefore, this article investigated the impact of culture and employee-focused criteria on productivity in Higher Education Institutions (HEIs) in Malaysia using intangible indicators through core values. The hypothesized relationship was tested using Structural Equation Modeling (SEM) with the PLS estimation technique. 429 questionnaires were returned from the target population. The results of the modelling revealed that the PLS estimation confirmed all the hypotheses tested as in the hypothesized model. The results generally support significant relationships between culture values, employee-focused values and productivity-focused values. The study also confirmed the mediating role of employee-focused values for the relationship between culture values and productivity-focused values. In conclusion, the empirically validated results supported the adequacy of the hypothezised model of the impact of culture and employee-focused criteria on productivity in HEI through value-based indicators.
Linking impulsivity to dysfunctional thought control and insomnia: a structural equation model.
Schmidt, Ralph E; Gay, Philippe; Ghisletta, Paolo; VAN DER Linden, Martial
2010-03-01
According to cognitive models of insomnia, excessive mental activity at bedtime may be viewed as an important impediment to the process of falling asleep. A further assumption of these models is that 'cognitive arousal' may be perpetuated and exacerbated by counterproductive strategies of thought management. As yet, little is known about factors that may predispose people to rely on these strategies when confronted with thoughts that keep them awake at night. This study examined the relations between impulsivity, use of different thought-control strategies and insomnia severity. A sample of 391 university students completed the UPPS Impulsive Behavior Scale, the Thought Control Questionnaire Insomnia-Revised and the Insomnia Severity Index. Correlation analyses revealed that two facets of impulsivity (urgency and lack of perseverance), two strategies of thought control (aggressive suppression and worry) and insomnia severity were positively associated. Follow-up structural equation modeling analyses showed that the two mentioned thought-control strategies mediated the effects of the two facets of impulsivity on sleep problems. These findings extend existing cognitive accounts of insomnia by suggesting how predisposing and perpetuating factors may be related: specific personality traits may incline individuals to respond with dysfunctional thought-control strategies to unwanted mental activity at night. PMID:19659917
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
Carretero Domínguez, Noelia; Gil-Monte, Pedro Rafael; Luciano Devis, Juan Vicente
2011-11-01
Most studies focusing on the antecedents and consequences of workplace bullying have used a cross-sectional design, which impedes determining the causality of the relationships. In the present work, we analyzed, by means of structural equation models, the relationship between workplace bullying and some variables that are considered antecedents (interpersonal conflicts, role ambiguity, role conflict, and workplace social support) or consequences (health complaints and inclination to absenteeism from work) of this phenomenon. Multicenter study with two phases. The sample consisted of 696 employees from 66 centers. Workplace bullying was assessed by means of the "Mobbing-UNIPSICO" questionnaire, and the other variables with frequency scales. The cross-sectional models indicated a significant association between role conflict, workplace social support, and workplace bullying in both study periods. Concerning the longitudinal relationships, only workplace social support was a significant predictor of workplace bullying, which, in turn, was a cross-sectional and longitudinal predictor of workers' health complaints. Our results show the mediating effect of workplace bullying between certain work conditions and health complaints, and it is recommendable to replicate these findings in a multi-occupational sample. PMID:22047848
On the specification of structural equation models for ecological systems
Grace, J.B.; Michael, Anderson T.; Han, O.; Scheiner, S.M.
2010-01-01
The use of structural equation modeling (SEM) is often motivated by its utility for investigating complex networks of relationships, but also because of its promise as a means of representing theoretical concepts using latent variables. In this paper, we discuss characteristics of ecological theory and some of the challenges for proper specification of theoretical ideas in structural equation models (SE models). In our presentation, we describe some of the requirements for classical latent variable models in which observed variables (indicators) are interpreted as the effects of underlying causes. We also describe alternative model specifications in which indicators are interpreted as having causal influences on the theoretical concepts. We suggest that this latter nonclassical specification (which involves another variable type-the composite) will often be appropriate for ecological studies because of the multifaceted nature of our theoretical concepts. In this paper, we employ the use of meta-models to aid the translation of theory into SE models and also to facilitate our ability to relate results back to our theories. We demonstrate our approach by showing how a synthetic theory of grassland biodiversity can be evaluated using SEM and data from a coastal grassland. In this example, the theory focuses on the responses of species richness to abiotic stress and disturbance, both directly and through intervening effects on community biomass. Models examined include both those based on classical forms (where each concept is represented using a single latent variable) and also ones in which the concepts are recognized to be multifaceted and modeled as such. To address the challenge of matching SE models with the conceptual level of our theory, two approaches are illustrated, compositing and aggregation. Both approaches are shown to have merits, with the former being preferable for cases where the multiple facets of a concept have widely differing effects in the system and the latter being preferable where facets act together consistently when influencing other parts of the system. Because ecological theory characteristically deals with concepts that are multifaceted, we expect the methods presented in this paper will be useful for ecologists wishing to use SEM. ?? 2010 by the Ecological Society of America.
Using structural equation modeling to investigate relationships among ecological variables
Malaeb, Z.A.; Kevin, Summers J.; Pugesek, B.H.
2000-01-01
Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1989). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables-sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude -0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0.1258. Natural variability had a positive direct effect on biodiversity of magnitude 0.5347 and a negative indirect effect mediated through growth potential of magnitude -0.1105 yielding a positive total effects of magnitude 0.4242. Sediment contamination had a negative direct effect on biodiversity of magnitude -0.1956 and a negative indirect effect on growth potential via biodiversity of magnitude -0.067. Biodiversity had a positive effect on growth potential of magnitude 0.8432, and growth potential had a positive effect on biodiversity of magnitude 0.3398. The correlation between biodiversity and growth potential was estimated at 0.7658 and that between sediment contamination and natural variability at -0.3769.
Pajulo, Marjukka; Tolvanen, Mimmi; Karlsson, Linnea; Halme-Chowdhury, Elina; Öst, Camilla; Luyten, Patrick; Mayes, Linda; Karlsson, Hasse
2015-07-01
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
Montero-Marin, Jesús; Piva Demarzo, Marcelo Marcos; Pereira, Joao Paulo; Olea, Marina; García-Campayo, Javier
2014-01-01
Background The training to become a dentist can create psychological distress. The present study evaluates the structure of the ‘Perceived Stress Questionnaire’ (PSQ), its internal consistency model and interrelatedness with burnout, anxiety, depression and resilience among dental students. Methods The study employed a cross-sectional design. A sample of Spanish dental students (n?=?314) completed the PSQ, the ‘Goldberg Anxiety and Depression Scale’ (GADS), ‘Connor-Davidson Resilience Scale’ (10-item CD-RISC) and ‘Maslach Burnout Inventory-Student Survey’ (MBI-SS). The structure was estimated using Parallel Analysis from polychoric correlations. Unweighted Least Squares was the method for factor extraction, using the Item Response Theory to evaluate the discriminative power of items. Internal consistency was assessed by squaring the correlation between the latent true variable and the observed variable. The relationships between the PSQ and the other constructs were analysed using Spearman’s coefficient. Results The results showed a PSQ structure through two sub-factors (‘frustration’ and ‘tenseness’) with regard to one general factor (‘perceived stress’). Items that did not satisfy discriminative capacity were rejected. The model fit were acceptable (GFI?=?0.98; RSMR?=?0.06; AGFI?=?0.98; NFI?=?0.98; RFI?=?0.98). All the factors showed adequate internal consistency as measured by the congeneric model (?0.91). High and significant associations were observed between perceived stress and burnout, anxiety, depression and resilience. Conclusions The PSQ showed a hierarchical bi-factor structure among Spanish dental students. Using the questionnaire as a uni-dimensional scale may be useful in perceived stress level discrimination, while the sub-factors could help us to refine perceived stress analysis and improve therapeutic processes. PMID:24466330
Carrard, Isabelle; Rebetez, Marie My Lien; Mobbs, Olivia; Van der Linden, Martial
2015-03-01
The Eating Disorder Examination-Questionnaire (EDE-Q) is a self-report questionnaire that is widely used to investigate the core features of eating disorders. The EDE-Q is derived from the Eating Disorder Examination, a semi-structured interview considered as the "gold standard" in the assessment of eating disorders. To verify the factor structure of both instruments, originally composed of four subscales, factor analyses have been conducted with various samples. Heterogeneous results were found. Because no study had investigated the factor structure of the EDE-Q in individuals with binge eating disorder, the goal of our study was to fill this gap. We started with a review of the studies on the EDE and EDE-Q factor structure to decide which models to compare. Among 21 studies that were identified, three models had been replicated several times. We compared these three models-a 22-item, 3-factor model, a brief 7-item, 3-factor model and a brief 8-item, 1-factor model-in two samples of participants, one with threshold and subthreshold criteria for binge eating disorder (N = 116) and one without eating disorders (N = 161). Confirmatory factor analysis revealed a good fit for the brief 7-item, 3-factor model for both populations, whereas other solutions were not acceptable. Cronbach's alpha coefficients of the three factors were acceptable to good, ranging between 0.714 and 0.953. The group with binge eating disorder symptoms had significantly higher scores for each factor. This brief 7-item instrument might be useful for screening or short interventions. PMID:25194301
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
ERIC Educational Resources Information Center
Richter, Jorg; Sagatun, Ase; Heyerdahl, Sonja; Oppedal, Brit; Roysamb, Espen
2011-01-01
Background: The SDQ is currently one of the internationally most frequently used screening instruments for child and adolescent mental health purposes. However, its structure, cross-cultural equivalence, and its applicability in ethnic minority groups is still a matter of discussion. Methods: SDQ self-report data of 5,379 ethnic Norwegian and 865…
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
Arhonditsis, George B.
Application of Bayesian structural equation modeling for examining phytoplankton dynamics to explore the spatiotemporal phytoplankton community patterns in the Neuse River Estuary (study period 1995e inorganic nitrogen), and temperature on total phytoplankton biomass and phytoplankton community structure
Factors of home dream recall: a structural equation model.
Schredl, Michael; Wittmann, Lutz; Ciric, Petra; Götz, Simon
2003-06-01
Previous research has indicated that personality factors such as openness to experience, creativity, visual memory, attitude toward dreams, and sleep behavior is related to home dream recall frequency (DRF). However, a study investigating all areas simultaneously within one sample in order to determine the percentage of variance explained by all variables and to take intercorrelations between the influencing factors into account has not been performed till now. The present study with 444 participants fills this gap. Using several indicators for each of the variables mentioned above, a structural equation model was tested. Although the model fit was satisfying, the four factors which were significantly related to DRF: personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams, explained only 8.4% of the total variance. As this value is considerably lower than those of studies investigating a single influencing factor and using similar measurement instruments in similar samples, one might speculate about possible expectancy effects in these previous studies, an effect which has been demonstrated for DRF in the laboratory setting. In addition, the small percentage of explained variance of each single factors (<3%) may indicate that other, in this study unmeasured, variables such as sleep duration (state aspect), introspection, and cognitive functioning immediately upon awakening (sleep inertia) show substantial covariance with the interindividual differences in DRF. Future studies should focus on longitudinal aspects in order to differentiate between state versus trait factors (although methodologic issues, e.g. the effect of the measurement technique on DRF itself, have to be clarified) and investigate additional variables which might be associated with DRF (see above). PMID:12753350
Chan, Raymond C K; Qing, Yonghong; Wu, Qiuping; Shum, David
2010-06-01
This study aimed to examine the latent structure of the Chinese version of the Comprehensive Assessment of Prospective Memory (CAPM) using confirmatory factor analysis. A total of 264 healthy Chinese participants (118 men and 146 women) took part in the study and their ages ranged from 17 to 90 years. There was no gender effect upon the frequency of prospective memory (PM) forgetting but age and education were found to be correlated significantly with these frequencies in the current sample. Results of the study also showed that the model with the best fit had a tripartite structure which consisted of a general memory factor (with all items loading on it) plus a basic activities of daily living as well as an instrumental activities of daily living factor. Furthermore, this tripartite model was robust across subgroups with respect to gender, education, and age. These findings provide support for the construct validity of the original CAPM and demonstrate its utility in another culture. PMID:20155572
ERIC Educational Resources Information Center
Song, Xin-Yuan; Lee, Sik-Yum
2006-01-01
Structural equation models are widely appreciated in social-psychological research and other behavioral research to model relations between latent constructs and manifest variables and to control for measurement error. Most applications of SEMs are based on fully observed continuous normal data and models with a linear structural equation.…
Maximum Likelihood Analysis of Nonlinear Structural Equation Models with Dichotomous Variables
ERIC Educational Resources Information Center
Song, Xin-Yuan; Lee, Sik-Yum
2005-01-01
In this article, a maximum likelihood approach is developed to analyze structural equation models with dichotomous variables that are common in behavioral, psychological and social research. To assess nonlinear causal effects among the latent variables, the structural equation in the model is defined by a nonlinear function. The basic idea of the…
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…
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.
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)…
Evaluation of Structural Equation Mixture Models: Parameter Estimates and Correct Class Assignment
ERIC Educational Resources Information Center
Tueller, Stephen; Lubke, Gitta
2010-01-01
Structural equation mixture models (SEMMs) are latent class models that permit the estimation of a structural equation model within each class. Fitting SEMMs is illustrated using data from 1 wave of the Notre Dame Longitudinal Study of Aging. Based on the model used in the illustration, SEMM parameter estimation and correct class assignment are…
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…
Abundant multisoliton structures of the Konopelchenko-Dubrovsky equation
NASA Astrophysics Data System (ADS)
Zhao, Hong; Han, Ji-Guang; Wang, Wei-Tao; An, Hong-Yong
2006-12-01
Using the homogenous balance method, the nonlinear transformations of the (2+1)-dimensional integrable Konopelchenko-Dubrovsky equation are given, and then some new special types of single solitary wave solution and the multisoliton solutions are constructed.
Development and Validation of the Cognitive Behavioral Physical Activity Questionnaire.
Schembre, Susan M; Durand, Casey P; Blissmer, Bryan J; Greene, Geoffrey W
2015-01-01
Purpose . Develop and demonstrate preliminary validation of a brief questionnaire aimed at assessing social cognitive determinants of physical activity (PA) in a college population. Design . Quantitative and observational. Setting . A midsized northeastern university. Subjects . Convenience sample of 827 male and female college students age 18 to 24 years. Measures . International Physical Activity Questionnaire and a PA stage-of-change algorithm. Analysis . A sequential process of survey development, including item generation and data reduction analyses by factor analysis, was followed with the goal of creating a parsimonious questionnaire. Structural equation modeling was used for confirmatory factor analysis and construct validation was confirmed against self-reported PA and stage of change. Validation analyses were replicated in a second, independent sample of 1032 college students. Results . Fifteen items reflecting PA self-regulation, outcome expectations, and personal barriers explained 65% of the questionnaire data and explained 28.6% and 39.5% of the variance in total PA and moderate-to-vigorous-intensity PA, respectively. Scale scores were distinguishable across the stages of change. Findings were similar when the Cognitive Behavioral Physical Activity Questionnaire (CBPAQ) was tested in a similar and independent sample of college students (40%; R (2) moderate-to-vigorous-intensity PA = .40; p < .001). Conclusion . The CBPAQ successfully explains and predicts PA behavior in a college population, warranting its incorporation into future studies aiming at understanding and improving on PA behavior in college students. PMID:25162324
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
Cognitive indicators of social anxiety in youth: a structural equation analysis.
Rudy, Brittany M; Davis, Thompson E; Matthews, Russell A
2014-01-01
Previous studies have demonstrated significant relationships among various cognitive variables such as negative cognition, self-efficacy, and social anxiety. Unfortunately, few studies focus on the role of cognition among youth, and researchers often fail to use domain-specific measures when examining cognitive variables. Therefore, the purpose of the present study was to examine domain-specific cognitive variables (i.e., socially oriented negative self-referent cognition and social self-efficacy) and their relationships to social anxiety in children and adolescents using structural equation modeling techniques. A community sample of children and adolescents (n=245; 55.9% female; 83.3% Caucasian, 9.4% African American, 2% Asian, 2% Hispanic, 2% "other," and 1.2% not reported) completed questionnaires assessing social cognition and social anxiety symptomology. Three latent variables were created to examine the constructs of socially oriented negative self-referent cognition (as measured by the SONAS scale), social self-efficacy (as measured by the SEQSS-C), and social anxiety (as measured by the SPAI-C and the Brief SA). The resulting measurement model of latent variables fit the data well. Additionally, consistent with the study hypothesis, results indicated that social self-efficacy likely mediates the relationship between socially oriented negative self-referent cognition and social anxiety, and socially oriented negative self-referent cognition yields significant direct and indirect effects on social anxiety. These findings indicate that socially oriented negative cognitions are associated with youth's beliefs about social abilities and the experience of social anxiety. Future directions for research and study limitations, including use of cross-sectional data, are discussed. PMID:24411119
NASA Technical Reports Server (NTRS)
Park, K. C.; Belvin, W. Keith
1990-01-01
A general form for the first-order representation of the continuous second-order linear structural-dynamics equations is introduced to derive a corresponding form of first-order continuous Kalman filtering equations. Time integration of the resulting equations 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 Kalman filtering equations involving only symmetric sparse N x N solution matrices.
N = 4 superextension of the Liouville equation with quaternion structure
Ivanov, E.A.; Krivonos, S.O.
1985-11-01
The authors construct an N = 4 supersymmetric extension of the Liouville equation. It has internal SU(2) x SU(2) gauge symmetry and can be adequately formulated in terms of a real quaternion N = 4 superfield on which definite conditions of Grassmann analyticity are imposed. Both the dynamic equations as well as the analyticity conditions follow from the zero-curvature representation on the superalgebra SU(1,1/2). It is shown that the obtained system is invariant with respect to transformations of the infinitedimensional superalgebra of the SU(2) superstring, the realization of these transformations differing from those previously known. The possible connection between the N = 4 Liouville equation and the theory of the SU(2) superstring is discussed.
Using SAS PROC TCALIS for multigroup structural equation modelling with mean structures.
Gu, Fei; Wu, Wei
2011-11-01
Multigroup structural equation modelling (SEM) is a technique frequently used to evaluate measurement invariance in social and behavioural science research. Before version 9.2, SAS was incapable of handling multigroup SEM. However, this limitation is resolved in PROC TCALIS in SAS 9.2. For the purpose of illustration, this paper provides a step-by-step guide to programming the tests of measurement invariance and partial invariance using PROC TCALIS for multigroup SEM with mean structures. Fit indices and parameter estimates are validated, thus providing an alternative tool for researchers conducting both applied and simulated studies. Other new features (e.g., different types of modelling languages and estimation methods) and limitations (e.g., ordered-categorical SEM and multilevel SEM) of the TCALIS procedure are also briefly discussed. PMID:21973099
Solving Differential Equations in Developmental Models of Multicellular Structures Expressed
Prusinkiewicz, Przemyslaw
Anabaena. Reference P. Federl and P. Prusinkiewicz: Solving differential equations in developmental models with a developmental model of the multicellular bacterium Anabaena. 1 Introduction Recent advances in genetics have solution by revisiting the diffusion-based developmental model of the blue-green alga Anabaena catenula [1
Structural equations for Killing tensors of arbitrary rank Thomas Wolf
Wolf, Thomas
for the integration of the geodesic equation for the Kerr metric by Carter and which is important in classical of arbitrary degree of the geodesic motion in a Riemannian space Vn into the form (FA ) ;k = P B kABFB . The FA Introduction As symmetries of a Riemannian space are associated with conservation laws of geodesic motion
Structural equations for Killing tensors of arbitrary rank* Thomas Wolf
Wolf, Thomas
* * the integration of the geodesic equation for the Kerr metric by Carter and which is important in c* *lassical * * P degree of the geodesic motion in a Riemannian space Vn into the form (FA);* *k= B k and [ ] in the following complete an* *tisymmetrization. But KT's are not only linked to geodesic motion. When motion
Parkes, John
The internal structure of the two-soliton solution to nonlinear evolution equations of a certain.m.campbell@strath.ac.uk and e.j.parkes@strath.ac.uk. Abstract We consider the class of nonlinear evolution equations that have N of nonlinear evolution equations of which the KdV equation is a member,and it is this class of equations
ERIC Educational Resources Information Center
Purdue Univ., Lafayette, IN. Educational Research Center.
The 116-item parent questionnaire is designed for parents of elementary school children. It is intended to be used with the child's mother, or the person acting as the child's mother. The questionnaire consists of a section devoted to demographic variables and scales measuring 14 parent variables: (1) parent's achievement aspirations for the…
Structure of Helicity and Global Solutions of Incompressible Navier-Stokes Equation
NASA Astrophysics Data System (ADS)
Lei, Zhen; Lin, Fang-Hua; Zhou, Yi
2015-05-01
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.
Spirtes, Peter
1 Using Path Diagrams as a Structural Equation Modelling Tool by Peter Spirtes, Thomas Richardson, Chris Meek, Richard Scheines, and Clark Glymour1 1. Introduction Linear structural equation models (SEMs
Spirtes, Peter
1 Using Path Diagrams as a Structural Equation Modelling Tool by Peter Spirtes, Thomas Richardson, Chris Meek, Richard Scheines, and Clark Glymour 1. Introduction Linear structural equation models (SEMs
Regularity and Global Structure of Solutions to Hamilton-Jacobi equations II. Convex initial data
Regularity and Global Structure of Solutions to Hamilton-Jacobi equations II. Convex initial data of Sciences, Beijing 100080, P. R. China jwang@amss.ac.cn Abstract. The paper is concerned with the Hamilton-Jacobi. Moreover, our results depend only on H and its domain of definition. Keywords: Hamilton-Jacobi equations
Effect of the Number of Variables on Measures of Fit in Structural Equation Modeling.
ERIC Educational Resources Information Center
Kenny, David A.; McCoach, D. Betsy
2003-01-01
Used three approaches to understand the effect of the number of variables in the model on model fit in structural equation modeling through computer simulation. Developed a simple formula for the theoretical value of the comparative fit index. (SLD)
Parental authority questionnaire.
Buri, J R
1991-08-01
A questionnaire was developed for the purpose of measuring Baumrind's (1971) permissive, authoritarian, and authoritative parental authority prototypes. It consists of 30 items per parent and yields permissive, authoritarian, and authoritative scores for both the mother and the father; each of these scores is derived from the phenomenological appraisals of the parents' authority by their son or daughter. The results of several studies have supported the Parental Authority Questionnaire as a psychometrically sound and valid measure of Baumrind's parental authority prototypes, and they have suggested that this questionnaire has considerable potential as a valuable tool in the investigation of correlates of parental permissiveness, authoritarianism, and authoritativeness. PMID:16370893
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.
Timothy Teo
2010-01-01
This study examined pre-service teachers’ self-reported behavioral intentions to use technology. Three hundred and fourteen\\u000a participants completed a survey questionnaire measuring their responses to six constructs from a research model that extends\\u000a the technology acceptance model (TAM) by including facilitating conditions and subjective norm. Structural equation modeling\\u000a was used as the main technique for data analysis. This study contributes to
Exploiting chordal structure in systems of polynomial equations
Cifuentes Pardo, Diego Fernando
2014-01-01
Chordal structure and bounded treewidth allow for efficient computation in linear algebra, graphical models, constraint satisfaction and many other areas. Nevertheless, it has not been studied whether chordality might also ...
$R$-matrices and Hamiltonian Structures for Certain Lax Equations
Chao-Zhong Wu
2013-05-06
In this paper a list of $R$-matrices on a certain coupled Lie algebra is obtained. With one of these $R$-matrices, we construct infinitely many bi-Hamiltonian structures for each of the two-component BKP and the Toda lattice hierarchies. We also show that, when such two hierarchies are reduced to their subhierarchies, these bi-Hamiltonian structures are reduced correspondingly.
Inverse diffraction grating of Maxwell's equations in biperiodic structures.
Bao, Gang; Cui, Tao; Li, Peijun
2014-02-24
Consider a time-harmonic electromagnetic plane wave incident on a perfectly conducting biperiodic surface (crossed grating). The diffraction is modeled as a boundary value problem for the three-dimensional Maxwell equation. The surface is assumed to be a small and smooth deformation of a planar surface. In this paper, a novel approach is developed to solve the inverse diffraction grating problem in the near-field regime, which is to reconstruct the surface with resolution beyond Rayleigh's criterion. The method requires only a single incident field with one polarization, one frequency, and one incident direction, and is realized by using the fast Fourier transform. Numerical results show that the method is simple, efficient, and stable to reconstruct biperiodic surfaces with subwavelength resolution. PMID:24663798
Review of Ballistic Limit Equations for Composite Structure Walls of Satellites
NASA Astrophysics Data System (ADS)
Schaefer, Frank K.*; Schneider, E.; Lambert, M.
2004-08-01
In this paper a review of existing ballistic limit equations for CFRP (Carbon Fibre Reinforced Plastics) structure walls of satellites is given, and two new ballistic limit equations are presented. The predictive capabilities of the equations are compared to a set of experimental hypervelocity impact test data of CFRP plates and CFRP honeycomb sandwich panels (satellite structure wall) from ENVISAT, AXAF, and a generic technology program. In the literature, three ballistic limit equations for sandwich panels (SP) made from CFRP face-sheets and Al- honeycomb (H/C) core were found and analyzed (Frost's approach, Approach using Christiansen's Whipple shield Ballistic Limit Equation (BLE), and Taylor's approach). Furthermore, in this paper, a new ballistic limit equation was proposed for CFRP H/C SP (Modified ESA Triple Wall Equation) and for composite panels (plates) with and without MLI attached to the surface. The amount of impact data on CFRP structure walls of satellites found in the literature was rather scarce. The new BLE for CFRP plates makes good predictions to the available set of test data. For the BLE for CFRP H/C SP, it was found that Frost's approach and application of Christiansen's BLE to CFRP H/C SP lead to an overprediction of the ballistic limit diameters for ENVISAT structure walls and the samples of the generic technology program. Taylor's approach and the newly designed MET ballistic limit equation have both yielded good predictions for all samples except for the AXAF samples that had rather thin-walled face-sheets and a thin Al H/C core: for these samples the predictions were conservative. Thus, for use in risk analysis tools for satellites (e. g. ESA's ESABASE/DEBRIS tool or NASA's BUMPER code), it is recommended to use either the MET or Taylor equation.
Maximum Likelihood Analysis of a Two-Level Nonlinear Structural Equation Model with Fixed Covariates
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan
2005-01-01
In this article, a maximum likelihood (ML) approach for analyzing a rather general two-level structural equation model is developed for hierarchically structured data that are very common in educational and/or behavioral research. The proposed two-level model can accommodate nonlinear causal relations among latent variables as well as effects…
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
Simsek, Gulhayat Golbasi; Noyan, Fatma
2009-01-01
Social sciences research often entails the analysis of data with a multilevel structure. An example of multilevel data is containing measurement on university students nested within instructors. This paper concentrates on multilevel analysis of structural equation modeling with educational data. Data used in this study were gathered from 17647…
ERIC Educational Resources Information Center
Willse, John T.; Goodman, Joshua T.; Allen, Nancy; Klaric, John
2008-01-01
The current research demonstrates the effectiveness of using structural equation modeling (SEM) for the investigation of subgroup differences with sparse data designs where not every student takes every item. Simulations were conducted that reflected missing data structures like those encountered in large survey assessment programs (e.g., National…
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…
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…
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…
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,…
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…
Functional structure model of human body and Yinyang-Wuxing equations
NASA Astrophysics Data System (ADS)
Fuli, Li
1987-12-01
The functional structure of human body is composed of five interacting functional subsystems. The connections between them are described by Wuxing theory. Wuxing diagram and Wuxing equations of human body are presented. The dynamics of human body is studied. Self-organization structure model of Jingluo is considered. Experimental tests of dynamics of human body are proposed.
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…
G. Iovane; P. Giordano
2005-01-01
In this work we introduce the hypersingular integral equations and analyze a realistic model of gravitational waveguides on a cantorian space-time. A waveguiding effect is considered with respect to the large scale structure of the Universe, where the structure formation appears as if it were a classically self-similar random process at all astrophysical scales. The result is that it seems
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.
Questioning Newton's second law: What is the structure of equations of motion?
Claus Lämmerzahl; Patricia Rademaker
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
Eichler West, R M; Wilcox, G L
1996-09-01
The solution to matrix equations which describe branched neuron-like structures can be made more efficient by minimizing matrix banding. This can be accomplished through the reordering of the compartmental numbering system. The renumbering method presented here extends upon the numbering method of Hines ((1984) Int. J. Biomed. Comput., 15: 69-76). A demonstration of efficient numbering will be presented for several general cases of branching structures. Theoretical computational savings can be estimated for the above structures. An algorithm to renumber a matrix already in Hines form will be described. Branched nerve equations, electrical networks and chemical reaction models are examples of systems which can benefit from this application. PMID:8884608
Sha, W.T.; Chao, B.T.; Soo, S.L.
1981-12-01
Local volume averaged conservation equations for multiphase flow in regions containing a distributed fixed solid structure with heat transfer are treated. In addition to the usual concept of volume porosity and distributed resistance, the anisotropic nature of the porous media is accounted for by formulating the equations in terms of velocities of phases associated with directional surface permeability. The resulting basic equations are in the form of differential integral transport equations with probability integrals based on the configurations and velocities of the interface. Limiting cases of pure stratified flow and highly dispersed mixture flow are noted. Validity and basis of the governing equations used in the COMMIX-2 code at its present stage of development are demonstrated.
Spatially Periodic Domain Structure in Coupled Reaction--Diffusion Equations for Segment Formation
NASA Astrophysics Data System (ADS)
Sakaguchi, Hidetsugu
2012-02-01
Segment formation is an important process of pattern formation in the developing vertebrate embryo. The mechanism of such pattern formation is considered to be different from that of Turing instability. We propose reaction--diffusion equations generating traveling pulses and coupled reaction--diffusion equations for two genes that generate a domain structure. Next, we construct a synthetic model for segment formation by combining the coupled reaction--diffusion equations. A spatially periodic domain structure is found in the numerical simulation of the model equation. It is shown that the wavelength of the spatially periodic pattern and the proportion of the sizes of the anterior and posterior domains in each segment can be controlled by adjusting some system parameters.
NASA Astrophysics Data System (ADS)
Bomont, J. M.; Bretonnet, J. L.
2002-06-01
Recently, we proposed a new self-consistent integral equation to obtain the pair correlation function of simple fluids in the case of pairwise additive forces [J. Chem. Phys. 114, 4141 (2001)]. Here this integral equation is applied to predict the structural and thermodynamic properties of xenon at supercritical temperatures and low densities, with the aim of examining the possible effect of the three-body dispersion forces. The validity of our extended integral equation is tested against molecular dynamics, and the results are compared to recent small-angle neutron scattering measurements [Formisano et al. Phys. Rev. E 58, 2648 (1998)] and thermodynamic properties. The good agreement found between semianalytic calculations and simulation or experimental results of the structural and thermodynamic properties gives clear indication of the efficiency of the use of our integral equation conjugated with an effective pair potential consisting of the Aziz-Slaman two-body potential plus the Axilrod-Teller three-body potential.
A family of solution algorithms for nonlinear structural analysis based on relaxation equations
NASA Technical Reports Server (NTRS)
Park, K. C.
1981-01-01
A family of hierarchical algorithms for nonlinear structural equations are presented. The algorithms are based on the Davidenko-Branin type homotopy and shown to yield consistent hierarchical perturbation equations. The algorithms appear to be particularly suitable to problems involving bifurcation and limit point calculations. An important by-product of the algorithms is that it provides a systematic and economical means for computing the stepsize at each iteration stage when a Newton-like method is employed to solve the systems of equations. Some sample problems are provided to illustrate the characteristics of the algorithms.
Fluid/Structure Interaction Studies of Aircraft Using High Fidelity Equations on Parallel Computers
NASA Technical Reports Server (NTRS)
Guruswamy, Guru; VanDalsem, William (Technical Monitor)
1994-01-01
Abstract Aeroelasticity which 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 modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST 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. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional super computers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; Byun, Chansup; VanDalsem, William (Technical Monitor)
1994-01-01
Aeroelasticity which 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 modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST 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. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional supercomputers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENASERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
QUESTIONNAIRE Anne Landfield Greig
develop and select cost-effective green building products. The data gathered from this questionnaire-cycle assessment is its comprehensive, multi- dimensional scope. Many green building to develop environmental profiles for building products. The goal is to help manufacturers and designers
The Depression Coping Questionnaire.
ERIC Educational Resources Information Center
Kleinke, Chris L.
College students (N=396), chronic pain patients (N=319), and schizophrenic veterans (N=43) completed the Depression Coping Questionnaire (DCQ) and the Beck Depression Inventory (BDI). Factor analysis of the DCQ identified eleven coping responses: social support, problem solving, self-blame/escape, aggression, indulgence, activities, medication,…
The Preschool Behavior Questionnaire
Lenore B. Behar
1977-01-01
In summary, the Preschool Behavior Questionnaire was developed as a screening instrument for use by preschool teachers, providing norms for children, ages 3–6. During the 34-month period since its publication in late 1974, the scale has been used to a considerable extent in the screening of young children. Those who have used the scale evaluate it highly. However, the variations
Facilities Sharing Questionnaire Survey.
ERIC Educational Resources Information Center
California Community Colleges, Sacramento. Office of the Chancellor.
In order to determine the extent to which the California community colleges share and borrow facilities, a questionnaire was sent to each California community college in January 1974. Sixty-six (96 percent) of the 69 districts responded. Analysis of the data revealed that the typical campus shared 7.5 facilities and borrowed 5.6. More than 37…
Date_____/_____/_____ PERSONAL TRAINING QUESTIONNAIRE
) for your blood pressure or heart condition? 7. Do you know of any other reason why you should not do in the last 3 months 2. Taking medication for high blood pressure 3. Hernia or other condition that may THURSDAY FRIDAY SATURDAY SUNDAY #12;Physical Activity Readiness Questionnaire (American College of Sports
A ballistic limit equation for hypervelocity impacts on CFRP Al H/C satellite structures
NASA Astrophysics Data System (ADS)
Ryan, S.; Schäfer, F.; Destefanis, R.; Lambert, M.
Composite sandwich panels consisting of Carbon Fiber Reinforced Plastic facesheets bonded to Aluminum honeycomb cores CFRP Al H C SP are amongst the most commonly used structures for satellites due to their relative low mass and high thermal and mechanical stability To assess the threat of micrometeoroid orbital debris M OD on a satellite mission equations which define the limits of structural perforation in terms of impactor mass velocity and angle are required This type of equation is referred to as a Ballistic Limit Equation BLE There is presently no validated BLE existing for application in the risk assessment of CFRP Al H C SP structures During a recent experimental test campaign performed in the framework of ESA Contract 16721 e g 1 using EMI s two-stage light-gas guns the ballistic performance of multiple representative CFRP Al HC SP structural configurations GOCE Radarsat-2 Herschel Planck BeppoSax was investigated The experimental results have been used to adjust and validate a new empirical BLE derived from an existing Whipple Shield BLE which provides a significant improvement in the accuracy of ballistic performance prediction over existing techniques Additionally the equation is capable of predicting the ballistic limit of an Electronic-box representative structure located behind the structural wall Good agreement with the experimental results is achieved for the vast majority of test set-ups For some set-ups the ballistic limit was conservatively predicted however this is attributed to the additional
Salama-Younes, Mareï; Montazeri, Ali; Ismaïl, Amany; Roncin, Charles
2009-01-01
Background The objectives of this study were to test the factor structure and internal consistency of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) in elderly French people, and to test the relationship between these two questionnaires. Methods Using a standard 'forward-backward' translation procedure, the English language versions of the two instruments (i.e. the 12-item General Health Questionnaire and the Subjective Vitality Scale) were translated into French. A sample of adults aged 58–72 years then completed both questionnaires. Internal consistency was assessed by Cronbach's alpha coefficient. The factor structures of the two instruments were extracted by confirmatory factor analysis (CFA). Finally, the relationship between the two instruments was assessed by correlation analysis. Results In all, 217 elderly adults participated in the study. The mean age of the respondents was 61.7 (SD = 6.2) years. The mean GHQ-12 score was 17.4 (SD = 8.0), and analysis showed satisfactory internal consistency (Cronbach's alpha coefficient = 0.78). The mean VS score was 22.4 (SD = 7.4) and its internal consistency was found to be good (Cronbach's alpha coefficient = 0.83). While CFA showed that the VS was uni-dimensional, analysis for the GHQ-12 demonstrated a good fit not only to the two-factor model (positive vs. negative items) but also to a three-factor model. As expected, there was a strong and significant negative correlation between the GHQ-12 and the VS (r = -0.71, P < 0.001). Conclusion The results showed that the French versions of the 12-item General Health Questionnaire (GHQ-12) and the Subjective Vitality Scale (VS) are reliable measures of psychological distress and vitality. They also confirm a significant negative correlation between these two instruments, lending support to their convergent validity in an elderly French population. The findings indicate that both measures have good structural characteristics. PMID:19265516
An integral equation theory for solvation effects on the molecular structural fluctuation
NASA Astrophysics Data System (ADS)
Matsumura, Yoshihiro; Sato, Hirofumi
2015-07-01
A new integral equation theory is proposed, which enables us to efficiently compute conformational distribution of a polyatomic molecule in solution phase. The solvation effect on the intramolecular correlation function is evaluated through a self-consistent procedure. In addition, the analytical expression of solvation free energy is derived, explicitly taking into account the molecular structural fluctuation. The derived equation establishes a direct route between the structural fluctuation and free energy of the molecule. The method was successfully applied to a series of n-alkanes in aqueous solutions to demonstrate the superiority of the proposed theory.
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…
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.
Biological fitness and the Price Equation in class-structured populations.
Grafen, Alan
2015-05-21
Price?s extended covariance selection mathematics is applied to class-structured populations with additional assumptions, to derive the 'genetic Price Equation with class structure'. Each individual belongs to a class, and there may be overlapping generations; the equation is genetic because the trait is restricted to an arbitrary weighted sum of allele frequencies. Two special cases are then considered, a demography-like case corresponding to Fisher's fundamental theorem of natural selection, and a sex-ratio-like case corresponding to Fisher's sex ratio argument: these differ in whether it is natural to assume that the per-capita or the total reproductive values of each class are maintained from the parental to the descendant population. These cases also match the two existing attempts to eliminate from the effects of natural selection those passive changes in allele frequencies that are caused by the class structure, and suggest improvements in one of them. In each case a more specialised Price Equation, and a 'fundamental theorem of natural selection', are proved, which hold out of class-structure equilibrium, showing that passive changes can be eliminated in more than one way, and hinting at the possibility of a more general formulation. Previous class-structured Price Equations and a 'fundamental theorem' are linked to these results. The power of Price's formal approach is vividly illustrated by this lucid conspectus of otherwise self-standing theories with confusing interconnections. PMID:25701635
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."
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.
Greenshields, Christopher J
2007-01-01
Howard Brenner has recently proposed modifications to the Navier-Stokes equations that relate to a diffusion of fluid volume that would be significant for flows with high density gradients. In a previous paper (Greenshields & Reese, 2007), we found these modifications gave good predictions of the viscous structure of shock waves in argon in the range Mach 1.0-12.0 (while conventional Navier-Stokes equations are known to fail above about Mach 2). However, some areas of concern with this model were a somewhat arbitrary choice of modelling coefficient, and potentially unphysical and unstable solutions. In this paper, we therefore present slightly different modifications to include molecule mass diffusion fully in the Navier-Stokes equations. These modifications are shown to be stable and produce physical solutions to the shock problem of a quality broadly similar to those from the family of extended hydrodynamic models that includes the Burnett equations. The modifications primarily add a diffusion term to t...
Food frequency questionnaires.
Pérez Rodrigo, Carmen; Aranceta, Javier; Salvador, Gemma; Varela-Moreiras, Gregorio
2015-01-01
Food Frequency Questionnaires are dietary assessment tools widely used in epidemiological studies investigating the relationship between dietary intake and disease or risk factors since the early '90s. The three main components of these questionnaires are the list of foods, frequency of consumption and the portion size consumed. The food list should reflect the food habits of the study population at the time the data is collected. The frequency of consumption may be asked by open ended questions or by presenting frequency categories. Qualitative Food Frequency Questionnaires do not ask about the consumed portions; semi-quantitative include standard portions and quantitative questionnaires ask respondents to estimate the portion size consumed either in household measures or grams. The latter implies a greater participant burden. Some versions include only close-ended questions in a standardized format, while others add an open section with questions about some specific food habits and practices and admit additions to the food list for foods and beverages consumed which are not included. The method can be self-administered, on paper or web-based, or interview administered either face-to-face or by telephone. Due to the standard format, especially closed-ended versions, and method of administration, FFQs are highly cost-effective thus encouraging its widespread use in large scale epidemiological cohort studies and also in other study designs. Coding and processing data collected is also less costly and requires less nutrition expertise compared to other dietary intake assessment methods. However, the main limitations are systematic errors and biases in estimates. Important efforts are being developed to improve the quality of the information. It has been recommended the use of FFQs with other methods thus enabling the adjustments required. PMID:25719771
Generalized estimating equations for ordinal data: a note on working correlation structures.
Lumley, T
1996-03-01
Generalized estimating equations (Liang, K. Y. and Zeger, S., 1986, Biometrika 73, 13-22) allow longitudinal or clustered data to be modeled with minimal assumptions about their dependence structures. Association structures for polytomous data have generally required the estimation of a large number of parameters. In many applications involving repeated categorical data, an ordinal structure is present. A range of association structures and computational methods for ordinal categorical data is described, based on the cumulative odds ratio, which allows much more parsimonious models. This permits the generalized estimating equation methodology to be used for smaller sets of ordinal data and with less effort expended on modeling associations. The method is illustrated on sets of ordinal data from medical studies. PMID:8934602
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.
What is the Structure of Equations of Motion? Testing Newton's Second Law
NASA Astrophysics Data System (ADS)
Rademaker, Dipl. Phys./Math. Patricia; Laemmerzahl, Claus
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. Re-laxing the validity of this axiom by allowing for higher order time derivatives in the equations of motion, for example, 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, that higher order derivatives induce a zitterbewegung. As a consequence, the main motion resulting from the second order equations of motion is rather resistant to modifications. The gauge principle leads to a gauge field with the property of a space metric. We confront this general scheme with experimental data.
Structural Equation Models for Interchangeable Dyads: Being the Same Makes a Difference
ERIC Educational Resources Information Center
Woody, Erik; Sadler, Pamela
2005-01-01
Structural equation modeling (SEM) offers a flexible method for studying the patterns of interdependence in partners' behavior, which lie at the heart of interactions and relationships. Although SEM has been applied to the study of distinguishable dyads, in which partners are distinguishable by type, such as male and female, it has rarely been…
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?…
Eight Myths About Causality and Structural Equation Kenneth A. Bollen and Judea Pearl
California at Los Angeles, University of
Chapter 15 Eight Myths About Causality and Structural Equation Models Kenneth A. Bollen and Judea accumulated. A variety of misunderstandings and myths about the nature of SEMs and their role in causal by presenting eight myths about causality and SEMs in the hope that this will lead to a more accurate
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);…
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…
ERIC Educational Resources Information Center
Butner, Jonathan; Amazeen, Polemnia G.; Mulvey, Genna M.
2005-01-01
The authors present a dynamical multilevel model that captures changes over time in the bidirectional, potentially asymmetric influence of 2 cyclical processes. S. M. Boker and J. Graham's (1998) differential structural equation modeling approach was expanded to the case of a nonlinear coupled oscillator that is common in bimanual coordination…
Bayesian Analysis of Nonlinear Structural Equation Models with Nonignorable Missing Data
ERIC Educational Resources Information Center
Lee, Sik-Yum
2006-01-01
A Bayesian approach is developed for analyzing nonlinear structural equation models with nonignorable missing data. The nonignorable missingness mechanism is specified by a logistic regression model. A hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm is used to produce the joint Bayesian estimates of…
Maximum Likelihood Estimation of Nonlinear Structural Equation Models with Ignorable Missing Data
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan; Lee, John C. K.
2003-01-01
The existing maximum likelihood theory and its computer software in structural equation modeling are established on the basis of linear relationships among latent variables with fully observed data. However, in social and behavioral sciences, nonlinear relationships among the latent variables are important for establishing more meaningful models…
A Robust Bayesian Approach for Structural Equation Models with Missing Data
ERIC Educational Resources Information Center
Lee, Sik-Yum; Xia, Ye-Mao
2008-01-01
In this paper, normal/independent distributions, including but not limited to the multivariate t distribution, the multivariate contaminated distribution, and the multivariate slash distribution, are used to develop a robust Bayesian approach for analyzing structural equation models with complete or missing data. In the context of a nonlinear…
ERIC Educational Resources Information Center
Mooijaart, Ab; Satorra, Albert
2009-01-01
In this paper, we show that for some structural equation models (SEM), the classical chi-square goodness-of-fit test is unable to detect the presence of nonlinear terms in the model. As an example, we consider a regression model with latent variables and interactions terms. Not only the model test has zero power against that type of…
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
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,…
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…
A STRUCTURAL EQUATION MODEL: GREECEâ€™S TOURISM DEMAND FOR TOURIST DESTINATION
Prasert Chaitip; Chukiat Chaiboonsri; Sandor Kovacs; Peter Balogh
2010-01-01
Structural equation model (LISREL 8) was applied to test the causal relationships between tourist travel motivations and tourist destination. A survey containing Likert scale questions was conducted to collect data from 100 tourists who had travelled to Greeceâ€™s tourist destination. With the help of factor analysis, four dimensions were identified for scales used in the study: travel cost satisfaction, tourism
Hypothesis Testing and Model Comparison in Two-Level Structural Equation Models.
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan
2001-01-01
Demonstrates the use of the well-known Bayes factor in the Bayesian literature for hypothesis testing and model comparison in general two-level structural equation models. Shows that the proposed method is flexible and can be applied to situations with a wide variety of nonnested models. (SLD)
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
Sahin, Elvan; Ertepinar, Hamide; Teksoz, Gaye
2012-01-01
The purpose of this study is to construct a structural equation model to examine the links among attitudes, values, and behaviors pertaining to sustainability, participation in outdoor recreation as well as gender and tendency to follow mass media for university students. The data were collected by on-line administration of a survey to 958…
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
ERIC Educational Resources Information Center
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…
Level-Specific Evaluation of Model Fit in Multilevel Structural Equation Modeling
ERIC Educational Resources Information Center
Ryu, Ehri; West, Stephen G.
2009-01-01
In multilevel structural equation modeling, the "standard" approach to evaluating the goodness of model fit has a potential limitation in detecting the lack of fit at the higher level. Level-specific model fit evaluation can address this limitation and is more informative in locating the source of lack of model fit. We proposed level-specific test…
ERIC Educational Resources Information Center
Elrod, Terry; Haubl, Gerald; Tipps, Steven W.
2012-01-01
Recent research reflects a growing awareness of the value of using structural equation models to analyze repeated measures data. However, such data, particularly in the presence of covariates, often lead to models that either fit the data poorly, are exceedingly general and hard to interpret, or are specified in a manner that is highly data…
ERIC Educational Resources Information Center
Raykov, Tenko; Amemiya, Yasuo
2008-01-01
A structural equation modeling method for examining time-invariance of variable specificity in longitudinal studies with multiple measures is outlined, which is developed within a confirmatory factor-analytic framework. The approach represents a likelihood ratio test for the hypothesis of stability in the specificity part of the residual term…
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
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):…
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…
Structure of variable-width square-well fluids from the reference hypernetted chain equation
Alejandro Gil-Villegas; Carlos Vega; Fernando Del Río; Anatol Malijevsky
1995-01-01
The problem of calculating the structure of square-well (SW) fluids in the context of non-conformal fluids is reviewed briefly. New and extensive results over a wide range of SW systems and thermodynamic states were obtained by means of the reference hypernetted chain (RHNC) integral equation. The results show that RHNC theory is in excellent agreement with the results of simulation,
Structure of variable-width square-well fluids from the reference hypernetted chain equation
ALEJANDRO GIL-VILLEGASt; CARLOS VEGA; ANATOL MALIJEVSKYII
The problem of calculating the structure of square-well (SW) fluids in the context of non-conformal fluids is reviewed briefly. New and extensive results over a wide range of SW systems and thermodynamic states were obtained by means of the reference hypernetted chain (RHNC) integral equation. The results show that RHNC theory is in excellent agreement with the results of simulation,
Implications of Recent Developments in Structural Equation Modeling for Counseling Psychology.
ERIC Educational Resources Information Center
Quintana, Stephen M.; Maxwell, Scott E.
1999-01-01
Reviews recent developments in structural equation modeling (SEM). Discusses issues critical to designing and evaluating SEM studies and recent technological developments. Examines innovations in applying SEM to different research contexts and designs. Also discusses procedures for redressing common problems and misunderstandings in the…
Dellar, Paul J.
Common Hamiltonian structure of the shallow water equations with horizontal temperature gradients of shallow water magnetohydrodynamics in velocity, height, and magnetic flux function variables. This Poisson, giving a simple and direct proof of the Jacobi identity in place of Ripa's long outline proof. The same
Teacher's Corner: A Review of Syllabi for a Sample of Structural Equation Modeling Courses
ERIC Educational Resources Information Center
Stapleton, Laura M.; Leite, Walter L.
2005-01-01
With increases in the use of structural equation modeling (SEM) in the social sciences, graduate course offerings in this statistical technique can be expected to increase. Knowledge of the content of current SEM course offerings may provide ideas to instructors developing new courses or enhancing current courses. This article discusses results…
Mobile computing acceptance factors in the healthcare industry: A structural equation model
Jen-her Wu; Shu-ching Wang; Li-min Lin
2007-01-01
Objective: This paper presents a revised technology acceptance model to examine what deter- mines mobile healthcare systems (MHS) acceptance by healthcare professionals. Method: Conformation factor analysis was performed to test the reliability and validity of the measurement model. The structural equation modeling technique was used to evaluate the causal model. Results: The results indicated that compatibility, perceived usefulness and perceived
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
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…
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…
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
Caro, Daniel H.; Sandoval-Hernández, Andrés; Lüdtke, Oliver
2014-01-01
The article employs exploratory structural equation modeling (ESEM) to evaluate constructs of economic, cultural, and social capital in international large-scale assessment (LSA) data from the Progress in International Reading Literacy Study (PIRLS) 2006 and the Programme for International Student Assessment (PISA) 2009. ESEM integrates the…
Painleve singularity structure analysis of three component Gross-Pitaevskii type equations
Kanna, T.; Sakkaravarthi, K.; Kumar, C. Senthil; Lakshmanan, M.; Wadati, M.
2009-11-15
In this paper, we have studied the integrability nature of a system of three-coupled Gross-Pitaevskii type nonlinear evolution equations arising in the context of spinor Bose-Einstein condensates by applying the Painleve singularity structure analysis. We show that only for two sets of parametric choices, corresponding to the known integrable cases, the system passes the Painleve test.
Women's Path into Science and Engineering Majors: A Structural Equation Model
ERIC Educational Resources Information Center
Camp, Amanda G.; Gilleland, Diane; Pearson, Carolyn; Vander Putten, Jim
2009-01-01
The intent of this study was to investigate the adequacy of Weidman's (1985, 1989) theoretical undergraduate socialization model as an empirical-based causal model pertaining to women's career path choice into a science or engineering (SE) major via structural equation modeling. Data were obtained from the Beginning Postsecondary Students…
Teacher's Corner: Structural Equation Modeling with the Sem Package in R
ERIC Educational Resources Information Center
Fox, John
2006-01-01
R is free, open-source, cooperatively developed software that implements the S statistical programming language and computing environment. The current capabilities of R are extensive, and it is in wide use, especially among statisticians. The sem package provides basic structural equation modeling facilities in R, including the ability to fit…
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan; Tang, Nian-Sheng
2007-01-01
The analysis of interaction among latent variables has received much attention. This article introduces a Bayesian approach to analyze a general structural equation model that accommodates the general nonlinear terms of latent variables and covariates. This approach produces a Bayesian estimate that has the same statistical optimal properties as a…
ERIC Educational Resources Information Center
Lee, Sik-Yum; Song, Xin-Yuan; Cai, Jing-Heng
2010-01-01
Analysis of ordered binary and unordered binary data has received considerable attention in social and psychological research. This article introduces a Bayesian approach, which has several nice features in practical applications, for analyzing nonlinear structural equation models with dichotomous data. We demonstrate how to use the software…
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…
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
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
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…
Perfectionism, Dysfunctional Attitudes, and Self-Esteem: A Structural Equations Analysis
ERIC Educational Resources Information Center
Ashby, Jeffrey S.; Rice, Kenneth G.
2002-01-01
The researchers in this study examined the association between adaptive and maladaptive dimensions of perfectionism and self-esteem. Confirmatory factor analysis and structural equations modeling were used to develop and test a model derived from theoretical links between perfectionism and self-esteem. Path models revealed that adaptive…
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
Cheung, Mike W. L.
2007-01-01
Mediators are variables that explain the association between an independent variable and a dependent variable. Structural equation modeling (SEM) is widely used to test models with mediating effects. This article illustrates how to construct confidence intervals (CIs) of the mediating effects for a variety of models in SEM. Specifically, mediating…
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…
An Assessment of Practical Solutions for Structural Equation Modeling with Complex Sample Data
ERIC Educational Resources Information Center
Stapleton, Laura M.
2006-01-01
This article discusses 5 approaches that secondary researchers might use to obtain robust estimates in structural equation modeling analyses when using data that come from large survey programs. These survey programs usually collect data using complex sampling designs and estimates obtained from conventional analyses that ignore the dependencies…
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…
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…
A Graphical Method for Assessing the Identification of Linear Structural Equation Models
ERIC Educational Resources Information Center
Eusebi, Paolo
2008-01-01
A graphical method is presented for assessing the state of identifiability of the parameters in a linear structural equation model based on the associated directed graph. We do not restrict attention to recursive models. In the recent literature, methods based on graphical models have been presented as a useful tool for assessing the state of…
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.…
What is the Structure of Equations of Motion? Testing Newton's Second Law
Claus Laemmerzahl
2010-01-01
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. Re-laxing the validity of this axiom by allowing for higher order time derivatives in the equations of motion, for example, would allow for a more general structure of interactions. We derive the
Developing Written Questionnaires: Determining if Questionnaires Should be Used
NSDL National Science Digital Library
Daniel R. Zalles
This module provides a strategy for determining whether a written questionnaire is an appropriate means of gathering data to meet the goals of an evaluation. The authors define which conditions are suitable for using questionnaires.
Tooze, Janet A.; Troiano, Richard P.; Carroll, Raymond J.; Moshfegh, Alanna J.; Freedman, Laurence S.
2013-01-01
Systematic investigations into the structure of measurement error of physical activity questionnaires are lacking. We propose a measurement error model for a physical activity questionnaire that uses physical activity level (the ratio of total energy expenditure to basal energy expenditure) to relate questionnaire-based reports of physical activity level to true physical activity levels. The 1999–2006 National Health and Nutrition Examination Survey physical activity questionnaire was administered to 433 participants aged 40–69 years in the Observing Protein and Energy Nutrition (OPEN) Study (Maryland, 1999–2000). Valid estimates of participants’ total energy expenditure were also available from doubly labeled water, and basal energy expenditure was estimated from an equation; the ratio of those measures estimated true physical activity level (“truth”). We present a measurement error model that accommodates the mixture of errors that arise from assuming a classical measurement error model for doubly labeled water and a Berkson error model for the equation used to estimate basal energy expenditure. The method was then applied to the OPEN Study. Correlations between the questionnaire-based physical activity level and truth were modest (r = 0.32–0.41); attenuation factors (0.43–0.73) indicate that the use of questionnaire-based physical activity level would lead to attenuated estimates of effect size. Results suggest that sample sizes for estimating relationships between physical activity level and disease should be inflated, and that regression calibration can be used to provide measurement error–adjusted estimates of relationships between physical activity and disease. PMID:23595007
General features and master equations for structurization in complex dusty plasmas
Tsytovich, V. N., E-mail: tsytov@lpi.ru [Russian Academy of Science, General Physics Institute (Russian Federation); Morfill, G. E., E-mail: gem@mpe.mpg.de [Max Planck Institute for Extraterrestrial Physics (Germany)
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.
NASA Astrophysics Data System (ADS)
Pankavich, S.; Shreif, Z.; Miao, Y.; Ortoleva, P.
2009-05-01
The kinetics of the self-assembly of nanocomponents into a virus, nanocapsule, or other composite structure is analyzed via a multiscale approach. The objective is to achieve predictability and to preserve key atomic-scale features that underlie the formation and stability of the composite structures. We start with an all-atom description, the Liouville equation, and the order parameters characterizing nanoscale features of the system. An equation of Smoluchowski type for the stochastic dynamics of the order parameters is derived from the Liouville equation via a multiscale perturbation technique. The self-assembly of composite structures from nanocomponents with internal atomic structure is analyzed and growth rates are derived. Applications include the assembly of a viral capsid from capsomers, a ribosome from its major subunits, and composite materials from fibers and nanoparticles. Our approach overcomes errors in other coarse-graining methods, which neglect the influence of the nanoscale configuration on the atomistic fluctuations. We account for the effect of order parameters on the statistics of the atomistic fluctuations, which contribute to the entropic and average forces driving order parameter evolution. This approach enables an efficient algorithm for computer simulation of self-assembly, whereas other methods severely limit the timestep due to the separation of diffusional and complexing characteristic times. Given that our approach does not require recalibration with each new application, it provides a way to estimate assembly rates and thereby facilitate the discovery of self-assembly pathways and kinetic dead-end structures.
Cattell, Raymond B; Boyle, Gregory J; Chant, David
2002-01-01
This theoretical note describes an expansion of the behavioral prediction equation, in line with the greater complexity encountered in models of structured learning theory (R. B. Cattell, 1996a). This presents learning theory with a vector substitute for the simpler scalar quantities by which traditional Pavlovian-Skinnerian models have hitherto been represented. Structured learning can be demonstrated by vector changes across a range of intrapersonal psychological variables (ability, personality, motivation, and state constructs). Its use with motivational dynamic trait measures (R. B. Cattell, 1985) should reveal new theoretical possibilities for scientifically monitoring change processes (dynamic calculus model: R. B. Cattell, 1996b), such as encountered within psychotherapeutic settings (R. B. Cattell, 1987). The enhanced behavioral prediction equation suggests that static conceptualizations of personality structure such as the Big Five model are less than optimal. PMID:11863038
Ovchinnikov, Yu. N., E-mail: ovc@itp.ac.ru [Max-Planck Institute for Physics of Complex Systems (Germany)
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.
The Toronto Empathy Questionnaire
Spreng, R. Nathan; McKinnon, Margaret C.; Mar, Raymond A.; Levine, Brian
2008-01-01
In order to formulate a parsimonious tool to assess empathy, we used factor analysis on a combination of self-report measures to examine consensus and developed a brief self-report measure of this common factor. The Toronto Empathy Questionnaire (TEQ) represents empathy as a primarily emotional process. In three studies, the TEQ demonstrated strong convergent validity, correlating positively with behavioral measures of social decoding, self-report measures of empathy, and negatively with a measure of Autism symptomatology. Moreover, it exhibited good internal consistency and high test-retest reliability. The TEQ is a brief, reliable, and valid instrument for the assessment of empathy. PMID:19085285
ATBC Study - Questionnaires and Forms
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Michigan Questionnaire Documentation System (MQDS)
Cheung, Gina-Qian
2013-04-03
The Michigan Questionnaire Documentation System (MQDS) is a powerful tool used to help create questionnaire documentation, with or without summary statistics, and other documentation based on the Blaise data model for a study. MQDS works by: 1...
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
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…
Global Bifurcation Structure and Parameter Dependence of the Hodgkin-Huxley Equations
NASA Astrophysics Data System (ADS)
Pan, Zhenxing; Doi, Shinji
The Hodgkin-Huxley (HH) equations of a squid giant axon are the most important mathematical model in electrophysiology and biology, and are also important in the development of various biologically inspired intelligent devices such as artificial neuron device and neural networks. The HH equations, however, include various constants or parameters whose values were determined based on physiological experiments, and thus the values possess inherent ambiguities. Also, the ‘constants’ are not really constant but change temporally. Thus, in this paper, we study the effects of the change of the constants or parameters on the dynamics of the HH equations and consider the parameter dependence and sensitivity of the equations; we study the bifurcation structure of the HH equations by changing their various parameters. In particular, we take the voltage-dependency of the dynamics of so-called gating variables as typical bifurcation parameters and show that the HH dynamics is very sensitive to the steady-state functions but not sensitive to the time ‘constants’ of gating variables.
Empathy in group psychoanalytic psychotherapy: questionnaire development.
Pavlovi?, Slavica; Vlastelica, Mirela
2008-09-01
The aim of this study is to develop a questionnaire that can observe empathy in group psychoanalytic psychotherapy and examine the structure of its factors. A questionnaire comprised of 160 items in five-point Likert-type scale was developed through analysis of communication and interaction related to empathizing during group sessions. The questionnaire was applied on 256 patients from 40 therapy groups in 9 cities in Croatia. All 20 group analysts are trained in the Institute for Group Analysis in Zagreb. The patients were selected based on group analysis criteria. After item discrimination and principal component analysis limited to five factors were assessed, 80 items were isolated, 20 of which made a control scale for socially desirable responses. Two parallel questionnaire forms were developed: Group-Analysis-Empathy 1 (GA-Em1) and Group-Analysis-Empathy 2 (GA-Em2). A new, reliable and valid questionnaire for empathy observation employable in group psychotherapy was designed. The following factors were isolated by means of factor analysis: 1. Emotional disclosure and sensibility; 2. Containing and metabolizing; 3. Immersion; 4. Resonance and responsiveness; 5. Insight. A new questionnaire on empathy in group-analytical psychotherapy can measure the capacity for emotional communication among group members and between the group and the group analyst - conductor. PMID:18982775
The Indeterministic Einstein Equation: Quantum Jumps, Spacetime Structure, and Dark Pseudomatter
Vladimir S. Mashkevich
2001-03-15
Current physics is faced with the fundamental problem of unifying quantum theory and general relativity, which would have resulted in quantum gravity. The main effort to construct the latter has been bent on quantizing spacetime structure, in particular metric. Meanwhile, taking account of the indeterministic aspect of the quantum description of matter, which manifests itself in quantum jumps, essentially affects classical spacetime structure and the Einstein equation. Quantum jumps give rise to a family of sets of simultaneous events, which implies the existence of universal cosmological time. In view of the jumps, the requirement for metric and its time derivative to be continuous implies that the Einstein equation should involve pseudomatter along with matter. Pseudomatter manifests itself only in gravitational effects, being thereby an absolutely dark ``matter''.
Unified QCD evolution equations and the dominant behaviour of structure functions at low x
NASA Astrophysics Data System (ADS)
Peschanski, R.; Wallon, S.
1995-02-01
We consider a system of evolution equations for quark and gluon structure functions satisfying the leading-logarithmic behaviour due to both QCD collinear (LL Q2) and infrared (LL1/ x) singularities. We show that these equations leave undetermined an arbitrary regular function of j in the Mellin-transformed weights. We consider the constraints resulting from energy-momentum conservation and from the decoupling of quark loops in the leading j-plane singularity. These constraints can be fulfilled without influencing the leading-log terms. As a particular consequence of the second constraint, the location of the leading singularity is determined in terms of the (LL1/ x) and (LL Q2) kernels. It leads to a value significantly lower than the LL1/ x evaluation, while remaining at j > 1, and compatible with the behaviour of structure functions observed at HERA.
Williamson, D A; Netemeyer, R G; Jackman, L P; Anderson, D A; Funsch, C L; Rabalais, J Y
1995-05-01
Risk factors for the development of eating disorder symptoms in female college athletes were studied using structural equation modeling. Three risk factors: social influence for thinness, athletic performance anxiety, and self-appraisal of athletic achievement, were selected for study. The association of these risk factors and eating disorder symptoms was hypothesized to be mediated by overconcern with body size and shape. The study sample was 98 women recruited from eight sports teams at a major university. Structural equation modeling analysis supported the hypothesized model and cross-validation of the model showed the findings to be stable. The results of this correlational study suggested that eating disorder symptoms in college athletes are significantly influenced by the interaction of sociocultural pressure for thinness, athletic performance anxiety, and negative self-appraisal of athletic achievement. If these risk factors lead to overconcern with body size and shape, then the emergence of an eating disorder is more probable. PMID:7620479
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.
Patelarou, Athina E; Dafermos, Vasilis; Brokalaki, Hero; Melas, Christos D; Koukia, Evmorfia
2015-06-01
The present study reports on the translation, cultural adaptation and validation of the Evidence-Based Practice Readiness Survey into the Greek language. Back-translation strategy for cross-cultural research was used to translate the questionnaire into Greek. The psychometric measurements that were performed included: reliability coefficients and explanatory factor analysis using a Varimax Rotation and Principal Components Method. In a further step, confirmatory analysis of the principal components was conducted. The internal consistency of the Greek Evidence-Based Practice Readiness Survey version, as assessed by the Cronbach's alpha coefficient, showed satisfactory results. The value for alpha was found equal to 0.85. The explanatory and confirmatory factor analysis demonstrated a four-factor structure of the tool. PMID:26057651
Internal null-controllability for a structurally damped beam equation, Version 4.0
Edward, Julian
Internal null-controllability for a structurally damped beam equation, Version 4.0 Julian Edward be an open subset of (0, 1). Let > 0. Consider the controllability problem: given u(x, 0) = u0(x) H2 (0, 1) H1 0 (0, 1), ut(x, 0) = u1(x) L2 (0, 1), can we find a control function f L2 ( Ã? (0, T
NASA Technical Reports Server (NTRS)
Thomas, G. R.
1973-01-01
Description of a variable step incremental procedure for the solution of nonlinear equations in finite element structural analysis. The proposed procedure is effective in improving the accuracy of the basic incremental technique and in providing, in addition, an accurate estimate of the discretization error. The proposed approach is highly appropriate for solving problems for which the user has no a priori estimate of the step size to use.
Quantum structure emerging from the transformation design of the Dirac equation
NASA Astrophysics Data System (ADS)
Lin, De-Hone
2014-06-01
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.
Xavier Antoine; Christophe Besse
2001-01-01
A transparent boundary condition for the two-dimensional linear Schrödinger equation is constructed through a microlocal approximation of the operator associating the Dirichlet data to the Neumann one in a “M-quasi hyperbolic” region. Several quasi-analytic characterization results concerning the asymptotic expansion of the total symbol of this operator in a subclass of inhomogeneous symbols with a quasi-polynomial-like structure are stated. In
Structural equation modeling in practice: A review and recommended two-step approach
James C. Anderson; David W. Gerbing
1988-01-01
In this article, we provide guidance for substantive researchers on the use of structural equation modeling in practice for theory testing and development. We present a comprehensive, two-step modeling approach that employs a series of nested models and sequential chi-square difference tests. We discuss the comparative advantages of this approach over a one-step approach. Considerations in specification, assessment of fit,
Asymptotics, structure, and integration of sound-proof atmospheric flow equations
NASA Astrophysics Data System (ADS)
Klein, Rupert
2009-07-01
Relative to the full compressible flow equations, sound-proof models filter acoustic waves while maintaining advection and internal waves. Two well-known sound-proof models, an anelastic model by Bannon and Durran’s pseudo-incompressible model, are shown here to be structurally very close to the full compressible flow equations. Essentially, the anelastic model is obtained by suppressing ? t ? in the mass continuity equation and slightly modifying the gravity term, whereas the pseudo-incompressible model results from dropping ? t p from the pressure equation. For length scales small compared to the density and pressure scale heights, the anelastic model reduces to the Boussinesq approximation, while the pseudo-incompressible model approaches the zero Mach number, variable density flow equations. Thus, for small scales, both models are asymptotically consistent with the full compressible flow equations, yet the pseudo-incompressible model is more general in that it remains valid in the presence of large density variations. For the relatively small density variations found in typical atmosphere-ocean flows, both models are found to yield very similar results, with deviations between models much smaller than deviations obtained when using different numerical schemes for the same model. This in agreement with Smolarkiewicz and Dörnbrack (Int J Numer Meth Fluids 56:1513-1519, 2007). Despite these useful properties, neither model can be derived by a low-Mach number asymptotic expansion for length scales comparable to the pressure scale height, i.e., for the regime they were originally designed for. Derivations of these models via scale analysis ignore an asymptotic time scale separation between advection and internal waves. In fact, only the classical Ogura and Phillips model, which assumes weak stratification of the order of the Mach number squared, can be obtained as a leading-order model from systematic low Mach number asymptotic analysis. Issues of formal asymptotics notwithstanding, the close structural similarity of the anelastic and pseudo-incompressible models to the full compressible flow equations makes them useful limit systems in building computational models for atmospheric flows. In the second part of the paper, we propose a second-order finite-volume projection method for the anelastic and pseudo-incompressible models that observes these structural similarities. The method is applied to test problems involving free convection in a neutral atmosphere, the breaking of orographic waves at high altitudes, and the descent of a cold air bubble in the small-scale limit. The scheme is meant to serve as a starting point for the development of a robust compressible atmospheric flow solver in future work.
Bayesian structural equation modeling: a more flexible representation of substantive theory.
Muthén, Bengt; Asparouhov, Tihomir
2012-09-01
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 Bayesian approach is particularly beneficial in applications where parameters are added to a conventional model such that a nonidentified model is obtained if maximum-likelihood estimation is applied. This approach is useful for measurement aspects of latent variable modeling, such as with confirmatory factor analysis, and the measurement part of structural equation modeling. Two application areas are studied, cross-loadings and residual correlations in confirmatory factor analysis. An example using a full structural equation model is also presented, showing an efficient way to find model misspecification. The approach encompasses 3 elements: model testing using posterior predictive checking, model estimation, and model modification. Monte Carlo simulations and real data are analyzed using Mplus. The real-data analyses use data from Holzinger and Swineford's (1939) classic mental abilities study, Big Five personality factor data from a British survey, and science achievement data from the National Educational Longitudinal Study of 1988. PMID:22962886
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
Anomalous wave structure in magnetized materials described by non-convex equations of state
Serna, Susana; Marquina, Antonio
2014-01-15
We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynamic properties of the material and the magnetic field as well as its possible rotation. We demonstrate that phase transitions induced by material properties do not necessarily imply the loss of genuine nonlinearity of the wavefields as is the case in classical hydrodynamics. The analytical expression of the nonlinearity factor allows us to determine the specific amount of magnetic field necessary to prevent formation of complex structure induced by phase transition in the material. We illustrate our analytical approach by considering two non-convex EOS that exhibit phase transitions and anomalous behavior in the evolution. We present numerical experiments validating the analysis performed through a set of one-dimensional Riemann problems. In the examples we show how to determine the appropriate amount of magnetic field in the initial conditions of the Riemann problem to transform a thermodynamic composite wave into a simple nonlinear wave.
Mixing Interview and Questionnaire Methods: Practical Problems in Aligning Data
ERIC Educational Resources Information Center
Harris, Lois R.; Brown, Gavin T. L.
2010-01-01
Structured questionnaires and semi-structured interviews are often used in mixed method studies to generate confirmatory results despite differences in methods of data collection, analysis, and interpretation. A review of 19 questionnaire-interview comparison studies found that consensus and consistency statistics were generally weak between…
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.…
Construct Validity of the Social Coping Questionnaire
ERIC Educational Resources Information Center
Swiatek, Mary Ann; Cross, Tracy L.
2007-01-01
The Social coping Questionnaire (SCQ) measures strategies used by gifted adolescents to minimize the negative effect they believe their high ability has on their social interactions. Previous studies have supported the factor structure, internal consistency, and test-retest reliability of the SCQ. The current study provides construct validity…
Technology Transfer Automated Retrieval System (TEKTRAN)
Psychometrically sound measures are considered a necessary condition for valid research. This study used structural equation modeling to examine the cross-cultural equivalence of a widely used measure of parental beliefs and practices regarding child feeding, the Child Feeding Questionnaire (CFQ) [B...
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
[Development of the Conscious Defensiveness Questionnaire (CDQ)].
Kunugimoto, Noriko; Yamasaki, Katsuyuki
2002-10-01
Conscious defensiveness has been found to mediate the relationship between hostility and coronary artery disease. In order to investigate the influence in Japan, the Conscious Defensiveness Questionnaire (CDQ) was developed and its validity and reliability were assessed in the present studies. The first study with college students (N = 419) was conducted to construct the CDQ as a 16-item questionnaire based on two preliminary researches. Factor analysis indicated that the 16 items in the CDQ conform to one factor structure, and the CDQ showed adequate factorial validity as well as high internal consistency. In the second study, the results of test-retest with college students (N = 225) revealed satisfactory stability of the CDQ over a 6- to 7-week period, and furthermore it showed construct validity in the relationships with peer ratings and nominations for college and graduate students (N = 191). Thus the present studies established the CDQ as a standardized questionnaire to measure conscious defensiveness. PMID:12516182
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
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
2011-04-01
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
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
Yang, Jinhua; Liu, Yanhui; Huang, Chunping; Zhu, Lefeng
2013-02-01
A higher turnover rate was identified in Chinese staff nurses and it was highly correlated with lower commitment. Empowering work environments that support professional practice have been positively related to nurse outcomes. This study was to integrate structural empowerment theory with magnet hospital characteristics and provide empirical evidence on the relationships between structural empowerment, professional practice environments and organizational commitment. A cross-sectional design was used to examine the relationships in a sample of 750 full-time nurses employed in five Chinese hospitals in 2011. Structural equation modeling was used to test the proposed hypotheses. The results support the hypothesized model. Professional practice environments partially mediated the relationship between empowerment and organizational commitment. Our findings suggest that higher empowerment facilitates the professional practice environments and commitment of these nurses. PMID:23425379
ERIC Educational Resources Information Center
Bassett, Hideko Hamada; Denham, Susanne; Mincic, Melissa; Graling, Kelly
2012-01-01
Research Findings: A theory-based 2-factor structure of preschoolers' emotion knowledge (i.e., recognition of emotional expression and understanding of emotion-eliciting situations) was tested using confirmatory factor analysis. Compared to 1- and 3-factor models, the 2-factor model showed a better fit to the data. The model was found to be…
Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack
2014-10-01
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
NASA Astrophysics Data System (ADS)
Ryan, S.; Schaefer, F.; Destefanis, R.; Lambert, M.
During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which was derived from an existing Whipple-shield BLE. This new BLE provided a good level of accuracy in predicting the ballistic performance of stand-alone sandwich panel structures. Additionally, the equation is capable of predicting the ballistic limit of a thin Al plate located at a standoff behind the sandwich panel structure. This thin plate is the representative of internal satellite systems, e.g. an Al electronic box cover, a wall of a metallic vessel, etc. Good agreement was achieved with both the experimental test campaign results and additional test data from the literature for the vast majority of set-ups investigated. For some experiments, the ballistic limit was conservatively predicted, a result attributed to shortcomings in correctly accounting for the presence of high surface density multi-layer insulation on the outer facesheet. Four existing BLEs commonly applied for application with stand-alone sandwich panels were reviewed using the new impact test data. It was found that a number of these common approaches provided non-conservative predictions for sandwich panels with CFRP facesheets.
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
Gene Network Inference via Structural Equation Modeling in Genetical Genomics Experiments
Liu, Bing; de la Fuente, Alberto; Hoeschele, Ina
2008-01-01
Our goal is gene network inference in genetical genomics or systems genetics experiments. For species where sequence information is available, we first perform expression quantitative trait locus (eQTL) mapping by jointly utilizing cis-, cis–trans-, and trans-regulation. After using local structural models to identify regulator–target pairs for each eQTL, we construct an encompassing directed network (EDN) by assembling all retained regulator–target relationships. The EDN has nodes corresponding to expressed genes and eQTL and directed edges from eQTL to cis-regulated target genes, from cis-regulated genes to cis–trans-regulated target genes, from trans-regulator genes to target genes, and from trans-eQTL to target genes. For network inference within the strongly constrained search space defined by the EDN, we propose structural equation modeling (SEM), because it can model cyclic networks and the EDN indeed contains feedback relationships. On the basis of a factorization of the likelihood and the constrained search space, our SEM algorithm infers networks involving several hundred genes and eQTL. Structure inference is based on a penalized likelihood ratio and an adaptation of Occam's window model selection. The SEM algorithm was evaluated using data simulated with nonlinear ordinary differential equations and known cyclic network topologies and was applied to a real yeast data set. PMID:18245846
Tice, Julie Anne Goodwin
1996-01-01
This research used structural equation modeling to test the construct validity of measures I I ion, and work of four global constructs: trait socialization, self-concept, organizational socialization' concept. Using ...
Structure of the space of solutions of Einstein's equations: A new variables approach
NASA Astrophysics Data System (ADS)
Saraykar, R. V.
1988-01-01
Following Ashtekar's new Hamiltonian formulation of general relativity [``A new Hamiltonian formulation of general relativity,'' Syracuse University preprint, 1986; Phys. Rev. Lett. 57, 2244 (1986); Proceedings of the Florence Conference on ``Constrained Systems'' (World Scientific, Singapore, 1986)], the results of Arms, Fischer, Marsden, and Moncrief [Ann. Inst. H. Poincaré 33, 147 (1980); Ann. Phys. (NY) 144, 81 (1982)] on the structure of the space of solutions of vacuum Einstein equations in the case of space-times admitting a compact Cauchy hypersurface are rederived and extended.
Structure of the space of solutions of Einstein's equations: A new variables approach
Saraykar, R.V.
1988-01-01
Following Ashtekar's new Hamiltonian formulation of general relativity (''A new Hamiltonian formulation of general relativity,'' Syracuse University preprint, 1986; Phys. Rev. Lett. 57, 2244 (1986); Proceedings of the Florence Conference on ''Constrained Systems'' (World Scientific, Singapore, 1986)), the results of Arms, Fischer, Marsden, and Moncrief (Ann. Inst. H. Poincare 33, 147 (1980); Ann. Phys. (NY) 144, 81 (1982)) on the structure of the space of solutions of vacuum Einstein equations in the case of space-times admitting a compact Cauchy hypersurface are rederived and extended.
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.
Structure properties of one-mode collaboration network model based on rate equation approach
NASA Astrophysics Data System (ADS)
Wang, Long; Ma, Yinghong
2014-12-01
The rate equation approach is very useful to describe the dynamic structure property of collaboration network, especially in calculating the node degree distribution and the joint degree distribution, and considering the correlation of node degrees. In this paper, we referee the two-mode collaboration network model (RDP), and translate it into one-mode RDP model. By the rate-equation approach, we study the node degree distribution in the one-mode RDP model (RDP) with numerical simulations verifying the feasibility of the model. It is proved that the node degree distribution of the model is a right-skewed power-law like distribution with the exponent ? in interval (1,3]. For the large enough node degree k, it can be proved that the node degree distribution is approximately power-law distribution. The joint degree distribution are also got by utilizing rate-equation approach and the node degree distribution. Through the joint degree distribution, we find that the correlation relationship of node degrees is nontrivial correlation relationship among the degrees of connected nodes that formed by spontaneously. Finally we get the clustering coefficient of the RDP model by calculating the mathematical expectation of degree distribution.
Post-1-Newtonian equations of motion for systems of arbitrarily structured bodies
Racine, E; Racine, Etienne; Flanagan, Eanna E.
2005-01-01
We give a surface integral derivation of post-1-Newtonian translational equations of motion for a system of arbitrarily structured bodies, including the coupling to all the bodies' mass and current multipole moments. The derivation requires only that the post-1-Newtonian vacuum field equations are satisfied in weak-field regions between the bodies; the bodies' internal gravity can be arbitrarily strong. The derivation extends previous results of Damour, Soffel and Xu (DSX) for weakly self-gravitating bodies for which the post-1-Newtonian field equations are satisfied everywhere. The derivation consists of a number of steps: (i) The definition of each body's current and mass multipole moments and center-of-mass worldline in terms of the behavior of the metric in a weak-field region surrounding the body. (ii) The definition for each body of a set of gravitoelectric and gravitomagnetic tidal moments, again in terms of the behavior of the metric in a weak-field region surrounding the body. For the special case of...
Analysing and Documenting Electronic Questionnaires
Jelke Bethlehem; Anco Hundepool
1998-01-01
Summary More and more, National Statistical Institutes (NSI's), research institutes, and commercial marketing research organisations are using computer-assisted interview systems for collecting survey data. The paper questionnaire is replaced by a computer program that guides the respondent through the questionnaire and checks the answers on the spot. The growing possibilities of computer hardware and software have made it possible to
Moerkerke, Beatrijs; Loeys, Tom; Vansteelandt, Stijn
2015-06-01
Inverse probability weighting for marginal structural models has been suggested as a strategy to estimate the direct effect of a treatment or exposure on an outcome in studies where the effect of mediator on outcome is subject to posttreatment confounding. This type of confounding, whereby confounders of the effect of mediator on outcome are themselves affected by the exposure, complicates mediation analyses and necessitates apt analysis strategies. In this article, we contrast the inverse probability weighting approach with the traditional path analysis approach to mediation analysis. We show that in a particular class of linear models, adjustment for posttreatment confounding can be realized via a fairly standard modification of the traditional path analysis approach. The resulting approach is simpler; by avoiding inverse probability weighting, it moreover results in direct effect estimators with smaller finite sample bias and greater precision. We further show that a particular variant of the G-estimation approach from the causal inference literature is equivalent with the path analysis approach in simple linear settings but is more generally applicable in settings with interactions and/or noncontinuous mediators and confounders. We conclude that the use of inverse probability weighting for marginal structural models to adjust for posttreatment confounding in mediation analysis is primarily indicated in nonlinear models for the outcome. PMID:25751514
Depth Averaged Equations Applied To Study of Defense Structures Effects On Dense Avalanche Flows
NASA Astrophysics Data System (ADS)
Naaim, M.; Bouvet-Naaim, F.; Faug, T.; Lachamp, P.
Avalanche zoning and protection devices are the complementary tools used to assess avalanche risk and protect persons and human activities in mountainous areas. Despite the intensive use of defense structures as protection against avalanches, their hydraulic and structural effects are not well known. Many structures were designed empirically using expert knowledge or knowledge developed in other domain such as hydraulic. Defence structures effects in terms of energy dissipation, deviation and snow retention are difficult to study in situ. The cost and difficulties of experiments, the danger and the weak annual number of avalanches in a given site, are the reasons why scientists oriented their research towards the use of numerical or laboratory physical models. This paper presents and discuss the possibilities to use depth averaged equations to study dense avalanche flows around defence structures. The used numerical resolu- tion method is based on an upwind numerical scheme. Equations are integrated on each cell of the mesh and the numerical fluxes are calculated thanks to a simplified Riemann solver where the retained solution is obtained as a combination of shock and rarefaction founctions. This allows taking into account the topography variation and jets and surges presence. These two characteristics are needed because both exper- imental and in situ observations showed a significant topography modifications and jets and surges formations during interaction between avalanche flows and structures. The case of vertical surfaces such as those made of concrete destined to deviate flows are treated by appropriated boundary condition functions. A discussion about the best way to integrate defence structures in such model is presented and discussed. This modelisation has, in a first time, been tested on analytical solutions and on experimen- tal laboratory scale model results. These tests have shown the capacity of this model, despite the strong hypothesis, to reproduce correctly some experimentally observed characteristics. In a second phase, this model was applied to study a well documented real case where a large avalanche flow interacted with a complex protection device composed of several types of defence structures. This comparison showed a good con- formity between the numerical results and in-situ observations concerning the global characteristics of the flows such as the deposit and the trajectory of the avalanche.
Kim, Min-Geun; Jang, Hong-Lae [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Seonho, E-mail: secho@snu.ac.kr [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)] [National Creative Research Initiatives Center for Isogeometric Optimal Design and Department of Naval Architecture and Ocean Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)
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.
Guidelines for a graph-theoretic implementation of structural equation modeling
Grace, James B.; Schoolmaster, Donald R., Jr.; Guntenspergen, Glenn R.; Little, Amanda M.; Mitchell, Brian R.; Miller, Kathryn M.; Schweiger, E. William
2012-01-01
Structural equation modeling (SEM) is increasingly being chosen by researchers as a framework for gaining scientific insights from the quantitative analyses of data. New ideas and methods emerging from the study of causality, influences from the field of graphical modeling, and advances in statistics are expanding the rigor, capability, and even purpose of SEM. Guidelines for implementing the expanded capabilities of SEM are currently lacking. In this paper we describe new developments in SEM that we believe constitute a third-generation of the methodology. Most characteristic of this new approach is the generalization of the structural equation model as a causal graph. In this generalization, analyses are based on graph theoretic principles rather than analyses of matrices. Also, new devices such as metamodels and causal diagrams, as well as an increased emphasis on queries and probabilistic reasoning, are now included. Estimation under a graph theory framework permits the use of Bayesian or likelihood methods. The guidelines presented start from a declaration of the goals of the analysis. We then discuss how theory frames the modeling process, requirements for causal interpretation, model specification choices, selection of estimation method, model evaluation options, and use of queries, both to summarize retrospective results and for prospective analyses. The illustrative example presented involves monitoring data from wetlands on Mount Desert Island, home of Acadia National Park. Our presentation walks through the decision process involved in developing and evaluating models, as well as drawing inferences from the resulting prediction equations. In addition to evaluating hypotheses about the connections between human activities and biotic responses, we illustrate how the structural equation (SE) model can be queried to understand how interventions might take advantage of an environmental threshold to limit Typha invasions. The guidelines presented provide for an updated definition of the SEM process that subsumes the historical matrix approach under a graph-theory implementation. The implementation is also designed to permit complex specifications and to be compatible with various estimation methods. Finally, they are meant to foster the use of probabilistic reasoning in both retrospective and prospective considerations of the quantitative implications of the results.
Bethanis, Kostas; Tzamalis, Pavlos; Hountas, Athanassios; Tsoucaris, Georges
2008-07-01
The algorithm [Bethanis, Tzamalis, Hountas & Tsoucaris (2002). Acta Cryst. A58, 265-269] which reformulates the quantum-mechanical problem of solving a Schrödinger (S) equation in a crystallographic context has been upgraded and tested for many aspects of convergence. The upgraded algorithm in reciprocal space aims at determining a wavefunction Phi(H) such that (a) Phi(H) fulfils the S equation within certain precision and (b) Phi(H) minimizes by least squares the differences between the calculated structure factors from the wavefunction and the observed ones. Calculations have been made with three molecules (11, 41 and 110 non-H atoms in the asymmetric unit) for different numbers of initially given phases. Three main questions have been addressed: (I) Does the iterative calculation of the wavefunction converge? (II) Do the calculated wavefunctions converge to a unique set of Phi(H) values independent of the initial random set of Phi(H)? (III) Is the calculated Phi(H) set a good approximation of a wavefunction able to produce within certain errors the correct values of the phases of the structure factors? Concerning questions (I) and (II), our results give a strong hint about fast convergence to a unique wavefunction independent of the arbitrary starting wavefunction. This is an essential prerequisite for practical applications. For question (III) in the case closer to the ab initio situation, the final mean phase error, respectively, for the three structures is 3, 26 and 28 degrees. The combination of (a) and (b) in the upgraded algorithm has been proved crucial especially for the results concerning the larger structures. PMID:18560161
Questionnaire Construction Manual. Annex: Literature Survey and Bibliography.
ERIC Educational Resources Information Center
Dyer, Robert; And Others
A literature review and bibliography on questionnaire construction are presented. The broad definition of questionnaire includes scales, structured interview forms, survey forms, and similar paper and pencil instruments used to elicit responses and collect information. A comprehensive literature search of journal articles, books, and reports in…
Factor Analysis of the Autism Spectrum Screening Questionnaire
ERIC Educational Resources Information Center
Posserud, Britt; Lundervold, Astri J.; Steijnen, Maaike C.; Verhoeven, Sophie; Stormark, Kjell Morten; Gillberg, Christopher
2008-01-01
The present study investigated the factor structure of parent and teacher Autism Spectrum Screening Questionnaire (ASSQ) in a population of 7-9 years old children. For validation purposes, factors derived were correlated with results on the Strengths and Difficulties Questionnaire (SDQ). A three-factor solution was identified on both parent and…
Construct Validity of the Children's Music-Related Behavior Questionnaire
ERIC Educational Resources Information Center
Valerio, Wendy H.; Reynolds, Alison M.; Morgan, Grant B.; McNair, Anne A.
2012-01-01
The purpose of this research was to investigate the construct validity of the Children's Music-Related Behavior Questionnaire (CMRBQ), an instrument designed for parents to document music-related behaviors about their children and themselves. The research problem was to examine the hypothesized factorial structure of the questionnaire. From a…
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.
An extended structure-based model based on a stochastic eddy-axis evolution equation
NASA Technical Reports Server (NTRS)
Kassinos, S. C.; Reynolds, W. C.
1995-01-01
We have proposed and implemented an extension of the structure-based model for weak deformations. It was shown that the extended model will correctly reduce to the form of standard k-e models for the case of equilibrium under weak mean strain. The realizability of the extended model is guaranteed by the method of its construction. The predictions of the proposed model were very good for rotating homogeneous shear flows and for irrotational axisymmetric contraction, but were seriously deficient in the case of plane strain and axisymmetric expansion. We have concluded that the problem behind these difficulties lies in the algebraic constitutive equation relating the Reynolds stresses to the structure parameters rather than in the slow model developed here. In its present form, this equation assumes that under irrotational strain the principal axes of the Reynolds stresses remain locked onto those of the eddy-axis tensor. This is correct in the RDT limit, but inappropriate under weaker mean strains, when the non-linear eddy-eddy interactions tend to misalign the two sets of principal axes and create some non-zero theta and gamma.
Kushner, M. G.; Krueger, R. F.; Wall, M. M.; Maurer, E. W.; Menk, J. S.; Menary, K. R.
2013-01-01
Background Clinical trials are typically designed to test the effect of a specific treatment on a single diagnostic entity. However, because common internalizing disorders are highly correlated (‘co-morbid ’), we sought to establish a practical and parsimonious method to characterize and quantify changes in a broad spectrum of internalizing psychopathology targeted for treatment in a clinical trial contrasting two transdiagnostic psychosocial interventions. Method Alcohol dependence treatment patients who had any of several common internalizing disorders were randomized to a six-session cognitive-behavioral therapy (CBT) experimental treatment condition or a progressive muscle relaxation training (PMRT) comparison treatment condition. Internalizing psychopathology was characterized at baseline and 4 months following treatment in terms of the latent structure of six distinct internalizing symptom domain surveys. Results Exploratory structural equation modeling (ESEM) identified a two-factor solution at both baseline and the 4-month follow-up : Distress (measures of depression, trait anxiety and worry) and Fear (measures of panic anxiety, social anxiety and agoraphobia). Although confirmatory factor analysis (CFA) demonstrated measurement invariance between the time-points, structural models showed that the latent means of Fear and Distress decreased substantially from baseline to follow-up for both groups, with a small but statistically significant advantage for the CBT group in terms of Distress (but not Fear) reduction. Conclusions The approach demonstrated in this study provides a practical solution to modeling co-morbidity in a clinical trial and is consistent with converging evidence pointing to the dimensional structure of internalizing psychopathology. PMID:23298776
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 high vorticity structures in incompressible 3D Euler equations
Agafontsev, D S; Mailybaev, A A
2015-01-01
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 $e^{-t/T_{\\ell}}$ and $e^{t/T_{\\omega}}$ describing compression in the transverse direction and the vorticity growth respectively, with the universal ratio $T_{\\ell}/T_{\\omega} \\approx 2/3$. We relate development of these structures to the gradual formation of the Kolmogorov energy spectrum $E_{k}\\propto\\, k^{-5/3}$, 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 $\\omega_{\\max} \\propto \\ell^{-2/3}$ for th...
2007-01-01
Background For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. Objectives The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability – athlete's personality – situation triangle. Methods Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199). Outcome measures included sport orientation (win and goal orientation and competitiveness), doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Results Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. Conclusion The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods. Future research, followed by policy development, should incorporate these factors to capture the complexity of the doping phenomenon and to identify points for effective anti-doping interventions. Sport governing bodies and anti-doping organisations need to recognise that using performance enhancements may be more of a rational, outcome optimizing behaviour than deviance and consider offering acceptable alternative performance-enhancing methods to doping. PMID:17996097
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
Betoret, Fernando Domenech
2009-01-01
This study examines the relationship between school resources, teacher self-efficacy, potential multi-level stressors and teacher burnout using structural equation modelling. The causal structure for primary and secondary school teachers was also examined. The sample was composed of 724 primary and secondary Spanish school teachers. The changes…
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)
Arms, J.M.; Marsden, J.E.; Moncrief, V.
1982-11-01
The space of solutions of Einstein's vacuum equations is shown to have conical singularities at each spacetime possessing a compact Cauchy surface of constant mean curvature and a nontrivial set of Killing fields. Similar results are shown for the coupled Einstein-Yang-Mills system. Combined with an appropriate slice theorem, the results show that the space of geometrically equivalent solutions is a stratified manifold with each stratum being a symplectic manifold characterized by the symmetry type of its members. Contents: Introduction 1. The Kuranishi map and its properties. 2. The momentum constraints. 3. The Hamiltonian constraints. 4. The Einstein-Yang-Mills system. 5. Discussion and examples.
Structural equation models to estimate risk of infection and tolerance to bovine mastitis
2013-01-01
Background One method to improve durably animal welfare is to select, as reproducers, animals with the highest ability to resist or tolerate infection. To do so, it is necessary to distinguish direct and indirect mechanisms of resistance and tolerance because selection on these traits is believed to have different epidemiological and evolutionary consequences. Methods We propose structural equation models with latent variables (1) to quantify the latent risk of infection and to identify, among the many potential mediators of infection, the few ones that influence it significantly and (2) to estimate direct and indirect levels of tolerance of animals infected naturally with pathogens. We applied the method to two surveys of bovine mastitis in the Walloon region of Belgium, in which we recorded herd management practices, mastitis frequency, and results of bacteriological analyses of milk samples. Results and discussion Structural equation models suggested that, among more than 35 surveyed herd characteristics, only nine (age, addition of urea in the rations, treatment of subclinical mastitis, presence of dirty liner, cows with hyperkeratotic teats, machine stripping, pre- and post-milking teat disinfection, and housing of milking cows in cubicles) were directly and significantly related to a latent measure of bovine mastitis, and that treatment of subclinical mastitis was involved in the pathway between post-milking teat disinfection and latent mastitis. These models also allowed the separation of direct and indirect effects of bacterial infection on milk productivity. Results suggested that infected cows were tolerant but not resistant to mastitis pathogens. Conclusions We revealed the advantages of structural equation models, compared to classical models, for dissecting measurements of resistance and tolerance to infectious diseases, here bovine mastitis. Using our method, we identified nine major risk factors that were directly associated with an increased risk of mastitis and suggested that cows were tolerant but not resistant to mastitis. Selection should aim at improved resistance to infection by mastitis pathogens, although further investigations are needed due to the limitations of the data used in this study. PMID:23496993
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?
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)
Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL
2011-01-01
The questionnaire is the instrument used for recording performance data on the nuclear material protection, control, and accountability (MPC&A) system at a nuclear facility. The performance information provides a basis for evaluating the effectiveness of the MPC&A system. The goal for the questionnaire is to provide an accurate representation of the performance of the MPC&A system as it currently exists in the facility. Performance grades for all basic MPC&A functions should realistically reflect the actual level of performance at the time the survey is conducted. The questionnaire was developed after testing and benchmarking the material control and accountability (MC&A) system effectiveness tool (MSET) in the United States. The benchmarking exercise at the Idaho National Laboratory (INL) proved extremely valuable for improving the content and quality of the early versions of the questionnaire. Members of the INL benchmark team identified many areas of the questionnaire where questions should be clarified and areas where additional questions should be incorporated. The questionnaire addresses all elements of the MC&A system. Specific parts pertain to the foundation for the facility's overall MPC&A system, and other parts pertain to the specific functions of the operational MPC&A system. The questionnaire includes performance metrics for each of the basic functions or tasks performed in the operational MPC&A system. All of those basic functions or tasks are represented as basic events in the MPC&A fault tree. Performance metrics are to be used during completion of the questionnaire to report what is actually being done in relation to what should be done in the performance of MPC&A functions.
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.
Structure of the set of stationary solutions of phase-lock equations in superconductivity
Mei-Qin Zhan
2007-01-01
In previous article [M. Zhan, Phase-lock equations and its connections to Ginzburg–Landau equations of superconductivity, J. Nonlinear Anal. 42 (2000) 1063–1075], we introduced a system of equations (phase-lock equations) to model the superconductivity phenomena. We investigated its connection to Ginzburg–Landau equations and proved the existence and uniqueness of both weak and strong solutions. In this article, we study the steady-state
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
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.
Butner, Jonathan; Amazeen, Polemnia G; Mulvey, Genna M
2005-06-01
The authors present a dynamical multilevel model that captures changes over time in the bidirectional, potentially asymmetric influence of 2 cyclical processes. S. M. Boker and J. Graham's (1998) differential structural equation modeling approach was expanded to the case of a nonlinear coupled oscillator that is common in bimanual coordination studies in which participants swing hand-held pendulums but is also applicable to social systems in general. The authors' nonlinear coupled oscillator model decomposed the fluctuations into a competitive component, unique to each individual variable, and a cooperative component that captured bidirectional influence. The authors' model also generated an index of the symmetry/asymmetry of bidirectional influence. Together, the models are useful quantitative tools for the study of interacting, changing processes. PMID:15998175
NASA Astrophysics Data System (ADS)
Luo, Huan; Greene, Raymond G.; Ghandehari, Kouros; Li, Ting; Ruoff, Arthur L.
1994-12-01
The crystal structures of three calcium chalcogenides CaS, CaSe, and CaTe were investigated by energy-dispersive x-ray-diffraction techniques using a synchrotron source to a static compression up to 52 GPa. For CaS and CaSe, a first-order phase transformation from the NaCl phase to the CsCl phase was observed at 40 and 38 GPa, respectively. For CaTe, it first transforms from the NaCl phase to an intermediate state possibly with a mixture of NaCl and MnP phases at 25 GPa, and then to the CsCl phase above 33 GPa. The phase transitions were reversible with small hysteresis. The equations of state and bulk moduli were obtained for all three compounds. The systematic behavior among the calcium chalcogenides under compression and the unusual transition sequence of CaTe are discussed.
Silveira, Marise Fagundes; Marôco, João P; Freire, Rafael Silveira; Martins, Andréa Maria Eleutério de Barros Lima; Marcopito, Luiz Francisco
2014-06-01
This study aimed to estimate the prevalence of impact of oral health conditions on physical and psychosocial dimensions among adolescents and to identify factors associated with severity of impact. The impact of oral health status was assessed by the instrument Oral Health Impact Profile (OHIP-14). The covariates were: socioeconomic status, habits and health care, use of dental services, and normative conditions of oral health. Structural equation modeling was performed, and 15.6% of adolescents reported impact in at least one dimension of the OHIP-14. The dimensions that showed the highest prevalence of impact were psychological distress (11.8%) and physical pain (6.6%). The number of teeth needing dental treatment, number of filled teeth, and CPI significantly affected severity of impact. In this adolescent population, unfavorable socioeconomic conditions were associated with reduced use of dental services, associated in turn with precarious oral health conditions and increased severity of impact. PMID:25099041
Lifetime abuse and self-harm in people with severe mental illness: A structural equation model.
O'Hare, Thomas; Shen, Ce; Sherrer, Margaret V
2015-07-01
We tested the hypothesis that lifetime physical and sexual abuse would have direct effects on self-harm (i.e., thoughts of self-harm, self-harming behaviors, and suicide attempts) and indirect effects on self-harm via negative appraisals of trauma and psychiatric symptoms in a sample of 242 clients with severe mental illness (SMI). Structural equation modeling partly confirmed our expectations. Although there was no direct effect between abuse and self-harm, abuse and self-harm appear to be fully mediated by negative appraisal and psychiatric symptoms. Limitations to this study include the cross-sectional nature of the research, which precludes firm causal inferences regarding the relationships among these factors. Longitudinal designs are needed to understand better the direct and indirect effects of abuse on people with SMI. (PsycINFO Database Record PMID:25866963
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.
Kramer, Lena; Hirsch, Oliver; Becker, Annette; Donner-Banzhoff, Norbert
2014-01-01
Introduction: The implementation of complex medical interventions in daily practice is often fraught with difficulties. According to the iterative phase model proposed by the British Medical Research Council (MRC), the development, implementation and evaluation of complex interventions should be theory-driven. A conceptual model that seems to be a promising framework is the Theory of planned behaviour (TPB). In our study we aimed to develop and validate a generic and multifaceted questionnaire based on the TPB to detect physicians’ willingness to implement complex medical interventions and the factors influencing this willingness. Methods: The questionnaire was developed according to the literature and was informed by previous qualitative research of our department. It was validated on the example of an electronic library of decision aids, arriba-lib. The sample consisted of 181 General Practitioners (GPs) who received a training regarding arriba-lib and subsequently filled in the questionnaire, assessing the TPB variables attitude, subjective norm, perceived behaviour control and intention. Follow-up assessments were conducted after two (assessing retest reliability) and eight weeks (assessing target behaviour). We performed a confirmatory factor analysis investigating the factorial structure of our questionnaire according to the TPB. Beside the calculation of the questionnaire’s psychometric properties we conducted a structural equation model and an ordinal regression to predict actual behaviour regarding the installation and application of arriba-lib. Results: The postulated three factorial model (attitude, subjective norm, perceived behaviour control) of our questionnaire based on the TPB was rejected. A two factorial model with a combined factor subjective norm/perceived behaviour control was accepted. The explained variance in the ordinal regression was low (Nagelkerke’s R2=.12). Neither attitude nor intention were able to predict the use or non-use of arriba-lib (attitude: p=.68, intention: p=.44). For the combined factor subjective norm/perceived behaviour control a significant, but small effect (p=.03) was shown. Conclusions: The TPB is not an adequate theoretical framework to guide the development of a generic questionnaire in the context of the implementation of complex interventions. To enable the successful implementation of complex medical interventions evaluators have to go through the whole development and evaluation process according to the MRC-model, without short cuts. Further, it has to be discussed if a generic instrument can be valid and useful. Regarding the TPB a publication bias regarding the theory’s applicability might have to be considered. PMID:24696674
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
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
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,…
Lin, Chin-Kai; Wu, Huey-Min; Lin, Chung-Hui; Wu, Yuh-Yih; Wu, Pei-Fang; Kuo, Bor-Chen; Yeung, Kwok-Tak
2012-10-01
The goal of this study was to examine the relationship between the validity of postural movement and bilateral motor integration in terms of sensory integration theory. Participants in this study were 61 Chinese children ages 48 to 70 months. Structural equation modeling was applied to assess the relation between measures tapping postural movement and bilateral motor integration: for postural movement, the measures involve the Monkey Task, Side-Sit Co-contraction, Prone on Elbows, Wheelbarrow Walk, Airplane, and Scooter Board Co-contraction from the DeGangi-Berk Test of Sensory Integration, and Standing Balance with Eyes Closed/Opened in Southern California Sensory Integration Tests. For bilateral motor integration, the measures chosen were the Rolling Pin Activity, Jump and Turn, Diadokokinesis, Drumming, and Upper Extremity Control from the DeGangi-Berk Test of Sensory Integration, and Cross the Midline in Southern California Sensory Integration Tests (SCSIT). Postural movement was highly correlated with the bilateral motor integration. The factor structure fit the theoretical conceptualization, classifying postural movement and bilateral motor integration together in the same category. Therapists could combine two separate objectives (postural movement and bilateral motor integration) of intervention in an activity to improve the adaptive skills based on the vestibular-proprioceptive integration. PMID:23265017
Questionnaires: the use and abuse of social survey methods in medical research
Eaden, J.; Mayberry, M.; Mayberry, J.
1999-01-01
We present a working review of survey methods based on market research technology. The structure of questionnaires, their distribution and analysis, are considered, together with techniques for increasing response rates.???Keywords: questionnaires; research methods PMID:10474722
NASA Astrophysics Data System (ADS)
Takayanagi, Sumiko; Bernstein, Lynne E.; Auer, Edward T.
2003-10-01
Structural equation modeling (SEM) was used to examine the statistical structure among sets of experiential (word age of acquisition and subjective familiarity) and lexical similarity (lexical equivalence class size and neighborhood density) variables for word identification and reaction time latency tasks. Stimuli were 240 vocoded monosyllabic English words with reduced intelligibility and altered similarity relationships. Participants detected a target word following a prime and on every trial reported the prime. The identification accuracy was estimated by words and phonemes correct, and detection latency was estimated by trimmed and harmonic mean RTs. A parsimonious SEM was chosen in terms of the chi-square and model fit indices that determine whether the models adequately described the particular associations of variables/interfactor relationships. The variable/factor error variances were constrained to be uncorrelated with each other in order to evaluate effects independently. A bootstrapping technique indicated that the regression weights of the top-down and bottom-up factors were small, but they were significant in the model. The variance accounted for (VAF) by the model was 7.1% for identification accuracy, and 5.2% for RT latency. The model also indicated that RT latency was highly influenced by prime identification accuracy (15% VAF). [Work supported by NIH/NIDCD00695.
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
A structural equation model of plant species richness and its application to a coastal wetland
Grace, J.B.; Pugesek, B.H.
1997-01-01
Studies of plant species richness have often emphasized the role of either community biomass (as an indicator of density effects) or abiotic factors. In this article we present a general model that simultaneously examines the relative importance of abiotic and density effects. General and specific models were developed to examine the importance of abiotic conditions, disturbance, and community biomass on plant species richness. Models were evaluated using structural equation modeling based on data from 190 plots across a coastal marsh landscape. The accepted model was found to explain 45% of the observed variation in richness, 75% of biomass, and 65% of light penetration. Model results indicate that abiotic conditions have both direct effects on the species pool and indirect effects on richness mediated through effects on biomass and shading. Effects of disturbance were found to be indirect via biomass. Strong density effects on richness were indicated by the results, and canopy light penetration was found to be a better predictor of richness than was biomass. Overall, it appears that richness in this coastal landscape is controlled in roughly equal proportions by abiotic influences on the species pool and density effects, with disturbance playing a lesser role. The structure of the general model presented should be applicable to a wide variety of herbaceous plant communities.
Kpadonou, A V; Rodrigues, M E
2015-01-01
We investigate in this paper the structures of neutron and quark stars in f(T) theory of gravity where T denotes the torsion scalar. Attention is attached to the TOV type equations of this theory and numerical integrations of these equations are performed with suitable EoS. We search for the deviation of the mass-radius diagrams for power-law and exponential type correction from the TT gravity. Our results show that for some values of the input parameters appearing in the considered models, f(T) theory promotes more the structures of the relativistic stars, in consistency with the observational data.
Questionnaires: Burden or Benefit to Universities?
ERIC Educational Resources Information Center
Petry, Glenn H.
1976-01-01
The problem of increasing questionnaire saturation experienced by colleges and universities is analyzed. Specific attention is focused upon attitudes toward questionnaires, reasons for nonresponse and factors that might improve the questionnaires, and, hopefully, the response rate. (LBH)
Scott-Parker, Bridie; Watson, Barry; King, Mark J; Hyde, Melissa K
2013-01-01
Young novice drivers constitute a major public health concern due to the number of crashes in which they are involved, and the resultant injuries and fatalities. Previous research suggests psychological traits (reward sensitivity, sensation seeking propensity), and psychological states (anxiety, depression) influence their risky behaviour. The relationships between gender, anxiety, depression, reward sensitivity, sensation seeking propensity and risky driving are explored. Participants (390 intermediate drivers, 17-25 years) completed two online surveys at a six month interval. Surveys comprised sociodemographics, Brief Sensation Seeking Scale, Kessler's Psychological Distress Scale, an abridged Sensitivity to Reward Questionnaire, and risky driving behaviour was measured by the Behaviour of Young Novice Drivers Scale. Structural equation modelling revealed anxiety, reward sensitivity and sensation seeking propensity predicted risky driving. Gender was a moderator, with only reward sensitivity predicting risky driving for males. Future interventions which consider the role of rewards, sensation seeking, and mental health may contribute to improved road safety for younger and older road users alike. PMID:22770376
75 FR 41876 - Federal Labor Standards Questionnaire(s); Complaint Intake Form
Federal Register 2010, 2011, 2012, 2013, 2014
2010-07-19
...FR-5376-N-66] Federal Labor Standards Questionnaire(s); Complaint Intake Form AGENCY: Office of the Chief Information Officer, HUD...Proposal: Federal Labor Standards Questionnaire(s); Complaint Intake Form. OMB Approval Number: 2501-0018. Form Numbers:...
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
NASA Astrophysics Data System (ADS)
Akbari, M. R.; Ganji, D. D.; Nimafar, M.; Ahmadi, A. R.
2014-12-01
In this paper, we aim to promote the capability of solving two complicated nonlinear differential equations: 1) Static analysis of the structure with variable cross section areas and materials with slope-deflection method; 2) the problem of one dimensional heat transfer with a logarithmic various surface A( x) and a logarithmic various heat generation G( x) with a simple and innovative approach entitled "Akbari-Ganji's method" (AGM). Comparisons are made between AGM and numerical method, the results of which reveal that this method is very effective and simple and can be applied for other nonlinear problems. It is significant that there are some valuable advantages in this method and also most of the differential equations sets can be answered in this manner while in other methods there is no guarantee to obtain the good results up to now. Brief excellences of this method compared to other approaches are as follows: 1) Differential equations can be solved directly by this method; 2) without any dimensionless procedure, equation(s) can be solved; 3) it is not necessary to convert variables into new ones. According to the aforementioned assertions which are proved in this case study, the process of solving nonlinear equation(s) is very easy and convenient in comparison to other methods.
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).
NASA Astrophysics Data System (ADS)
Meng, Xiang-Hua
2014-11-01
Taking the inhomogeneities of media and nonuniform boundaries into account, the variable-coefficient equations can describe more realistic physical phenomena than their constant-coefficient counterparts. In this paper, a variable-coefficient forced Kadomtsev-Petviashvili equation with inhomogeneous nonlinearity, dispersion, perturbed term and external force is investigated. Using a modified dependent variable transformation, this equation is first bilinearized. Then, the N-soliton solutions in two different kinds of determinant structure, that is the Wronskian and Grammian determinant soliton solutions for the variable-coefficient forced Kadomtsev-Petviashvili equation are presented and verified under certain coefficient constraints. The sample soliton solutions are given by choosing suitable determinant elements, and several kinds of soliton evolution situations are discussed and illustrated.
An informant questionnaire for detecting Alzheimer's disease: are some items better than others?
Sikkes, Sietske A M; Knol, Dirk L; van den Berg, Mark T; de Lange-de Klerk, Elly S M; Scheltens, Philip; Klein, Martin; Pijnenburg, Yolande A L; Uitdehaag, Bernard M J
2011-07-01
A decline in everyday cognitive functioning is important for diagnosing dementia. Informant questionnaires, such as the informant questionnaire on cognitive decline in the elderly (IQCODE), are used to measure this. Previously, conflicting results on the IQCODEs ability to discriminate between Alzheimer's disease (AD), mild cognitive impairment (MCI), and cognitively healthy elderly were found. We aim to investigate whether specific groups of items are more useful than others in discriminating between these patient groups. Informants of 180 AD, 59 MCI, and 89 patients with subjective memory complaints (SMC) completed the IQCODE. To investigate the grouping of questionnaire items, we used a two-dimensional graded response model (GRM).The association between IQCODE, age, gender, education, and diagnosis was modeled using structural equation modeling. The GRM with two groups of items fitted better than the unidimensional model. However, the high correlation between the dimensions (r=.90) suggested unidimensionality. The structural model showed that the IQCODE was able to differentiate between all patient groups. The IQCODE can be considered as unidimensional and as a useful addition to diagnostic screening in a memory clinic setting, as it was able to distinguish between AD, MCI, and SMC and was not influenced by gender or education. PMID:22882809
NASA Technical Reports Server (NTRS)
Byun, Chansup; Guruswamy, Guru P.
1993-01-01
This paper presents a procedure for computing the aeroelasticity of wing-body configurations on multiple-instruction, multiple-data (MIMD) parallel computers. In this procedure, fluids are modeled using Euler equations discretized by a finite difference method, and structures are modeled using finite element equations. The procedure is designed in such a way that each discipline can be developed and maintained independently by using a domain decomposition approach. A parallel integration scheme is used to compute aeroelastic responses by solving the coupled fluid and structural equations concurrently while keeping modularity of each discipline. The present procedure is validated by computing the aeroelastic response of a wing and comparing with experiment. Aeroelastic computations are illustrated for a High Speed Civil Transport type wing-body configuration.
Questionnaire Research in Higher Education.
ERIC Educational Resources Information Center
Inoue, Yukiko
The objective of this paper is to discuss the survey as a research method based on three questionnaire surveys developed and administered in educational settings: (1) a survey exploring the status aspiration and gender awareness of undergraduate women completed by 62 respondents; (2) a survey of computer-assisted instruction completed by 111…
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?
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…
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
ERIC Educational Resources Information Center
Byrne, Barbara M.
2001-01-01
Uses a confirmatory factor analytic (CFA) model as a paradigmatic basis for the comparison of three widely used structural equation modeling computer programs: (1) AMOS 4.0; (2) EQS 6; and (3) LISREL 8. Comparisons focus on aspects of programs that bear on the specification and testing of CFA models and the treatment of incomplete, nonnormally…
ERIC Educational Resources Information Center
Marsh, Herbert W.; Ludtke, Oliver; Robitzsch, Alexander; Trautwein, Ulrich; Asparouhov, Tihomir; Muthen, Bengt; Nagengast, Benjamin
2009-01-01
This article is a methodological-substantive synergy. Methodologically, we demonstrate latent-variable contextual models that integrate structural equation models (with multiple indicators) and multilevel models. These models simultaneously control for and unconfound measurement error due to sampling of items at the individual (L1) and group (L2)…
ERIC Educational Resources Information Center
Lee, Sik-Yum; Xia, Ye-Mao
2006-01-01
By means of more than a dozen user friendly packages, structural equation models (SEMs) are widely used in behavioral, education, social, and psychological research. As the underlying theory and methods in these packages are vulnerable to outliers and distributions with longer-than-normal tails, a fundamental problem in the field is the…
Tomas Chamorro-Premuzic; Montserrat Gomà-i-Freixanet; Adrian Furnham; Anna Muro
2009-01-01
This study replicates and extends a recent study on personality, intelligence and uses of music [Chamorro-Premuzic, T., & Furnham, A. (2007). Personality and music: Can traits explain how people use music in everyday life? British Journal of Psychology, 98, 175–185] using Spanish participants and structural equation modeling. Data from 245 university students showed that, in line with our hypotheses, individuals
ERIC Educational Resources Information Center
Nevitt, Johnathan; Hancock, Gregory R.
Though common structural equation modeling (SEM) methods are predicated upon the assumption of multivariate normality, applied researchers often find themselves with data clearly violating this assumption and without sufficient sample size to use distribution-free estimation methods. Fortunately, promising alternatives are being integrated into…
ERIC Educational Resources Information Center
Enders, Craig K.
2008-01-01
Recent missing data studies have argued in favor of an "inclusive analytic strategy" that incorporates auxiliary variables into the estimation routine, and Graham (2003) outlined methods for incorporating auxiliary variables into structural equation analyses. In practice, the auxiliary variables often have missing values, so it is reasonable to…
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…
Keke Lai; Ken Kelley
2011-01-01
In addition to evaluating a structural equation model (SEM) as a whole, often the model parameters are of interest and confidence intervals for those parameters are formed. Given a model with a good overall fit, it is entirely possible for the targeted effects of interest to have very wide confidence intervals, thus giving little information about the magnitude of the
ERIC Educational Resources Information Center
Museus, Samuel D.; Vue, Rican
2013-01-01
The purpose of this study is to examine socioeconomic differences in the interpersonal factors that influence college access among Asian Americans and Pacific Islanders (AAPIs). Data on 1,460 AAPIs from the Education Longitudinal Study (ELS: 02/06) were analyzed using structural equation modeling techniques. Findings suggest that parental…
ERIC Educational Resources Information Center
Ashida, Akemi
2015-01-01
Studies have investigated factors that impede enrolment in Honduras. However, they have not analysed individual factors as a whole or identified the relationships among them. This study used longitudinal data for 1971 children who entered primary schools from 1986 to 2000, and employed structural equation modelling to examine the factors…
ERIC Educational Resources Information Center
Farh, Jiing-Lih; Dobbins, Gregory H.
1989-01-01
Used structural equation model analysis to examine relationship between self-esteem and leniency bias in self-reports of performance. Results from 64 undergraduate students revealed that leniency bias was positively correlated with self-esteem. Findings also suggest that relationship between self-esteem and leniency bias was more positive when…
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…
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
Brussino, Silvina; Medrano, Leonardo; Sorribas, Patricia; Rabbia, Hugo H
2011-05-01
The aim of this study was to create an explanatory model that allows analyzing the predictive power of a set of variables related to political knowledge; more specifically, to analyze the relationship between the education level of young adults and the variables, interest in politics and internal political efficacy. We also analyzed the combined relationship between these variables, together with age, and political knowledge. We worked with a sample group of 280 young adults between the ages of 18-30 from the city of Córdoba (Argentina). The data was subjected to a structural equation modelling SEM analysis, which allowed for the corroboration of the following hypotheses: the higher the education level, the more the interest in politics; the higher the education level, the better the perception of internal political efficacy; the higher the education level, the more the political knowledge; the more the interest in politics, the more the political knowledge; and the better the perception of internal political efficacy, the more interest in politics. Moreover, the following hypotheses could not be verified: the older an individual, the more the political knowledge; and the better the perception of internal political efficacy, the more the political knowledge. The model obtained allows for discussion of the explanatory value of these socio-cognitive variables. PMID:21568176
A structural equation analysis of family accommodation in pediatric obsessive-compulsive disorder.
Caporino, Nicole E; Morgan, Jessica; Beckstead, Jason; Phares, Vicky; Murphy, Tanya K; Storch, Eric A
2012-01-01
Family accommodation of symptoms is counter to the primary goals of cognitive-behavioral therapy for pediatric obsessive-compulsive disorder (OCD) and can pose an obstacle to positive treatment outcomes. Although increased attention has been given to family accommodation in pediatric OCD, relatively little is known about associated child and parent characteristics, and their mediating/moderating effects. This study examined a structural equation model of parent and child variables related to parent reports of family accommodation. Sixty-one children with OCD (ages 6-17 years, 39% female) and their parents were recruited from a university-based clinic. They were administered clinician- and parent-rated measures of child OCD symptom severity, OCD-specific impairment, internalizing problems, and externalizing problems as well as parent anxiety, depression, empathy, consideration of future consequences, and accommodation. Results generally supported the hypothesized model. Family accommodation mediated the relationship between OCD symptom severity and parent-rated functional impairment; child internalizing problems mediated the relationship between parent anxiety and family accommodation; and parent empathy and consideration of future consequences interacted to predict family accommodation. Child externalizing problems were significantly associated with family accommodation but neither of these two variables was associated with parent depression. Findings suggest that reductions in family accommodation might be maximized by routinely screening for comorbid psychopathology in children with OCD and their parents, and using prescriptive or modular approaches to intervention. Directions for future research are discussed. PMID:21842196
Determinants of phubbing, which is the sum of many virtual addictions: A structural equation model.
Karada?, Engin; Tosunta?, ?ule Betül; Erzen, Evren; Duru, Pinar; Bostan, Nalan; ?ahin, Berrak Mizrak; Çulha, ?lkay; Babada?, Burcu
2015-06-01
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
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
Stress and Resilience in Functional Somatic Syndromes – A Structural Equation Modeling Approach
Fischer, Susanne; Lemmer, Gunnar; Gollwitzer, Mario; Nater, Urs M.
2014-01-01
Background Stress has been suggested to play a role in the development and perpetuation of functional somatic syndromes. The mechanisms of how this might occur are not clear. Purpose We propose a multi-dimensional stress model which posits that childhood trauma increases adult stress reactivity (i.e., an individual's tendency to respond strongly to stressors) and reduces resilience (e.g., the belief in one's competence). This in turn facilitates the manifestation of functional somatic syndromes via chronic stress. We tested this model cross-sectionally and prospectively. Methods Young adults participated in a web survey at two time points. Structural equation modeling was used to test our model. The final sample consisted of 3?054 participants, and 429 of these participated in the follow-up survey. Results Our proposed model fit the data in the cross-sectional (?2(21) ?=?48.808, p<.001, CFI ?=?.995, TLI ?=?.992, RMSEA ?=?.021, 90% CI [.013.029]) and prospective analyses (?2(21) ?=?32.675, p<.05, CFI ?=?.982, TLI ?=?.969, RMSEA ?=?.036, 90% CI [.001.059]). Discussion Our findings have several clinical implications, suggesting a role for stress management training in the prevention and treatment of functional somatic syndromes. PMID:25396736
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
Nonparametric Estimates of Gene × Environment Interaction Using Local Structural Equation Modeling.
Briley, Daniel A; Harden, K Paige; Bates, Timothy C; Tucker-Drob, Elliot M
2015-09-01
Gene × environment (G × E) interaction studies test the hypothesis that the strength of genetic influence varies across environmental contexts. Existing latent variable methods for estimating G × E interactions in twin and family data specify parametric (typically linear) functions for the interaction effect. An improper functional form may obscure the underlying shape of the interaction effect and may lead to failures to detect a significant interaction. In this article, we introduce a novel approach to the behavior genetic toolkit, local structural equation modeling (LOSEM). LOSEM is a highly flexible nonparametric approach for estimating latent interaction effects across the range of a measured moderator. This approach opens up the ability to detect and visualize new forms of G × E interaction. We illustrate the approach by using LOSEM to estimate gene × socioeconomic status interactions for six cognitive phenotypes. Rather than continuously and monotonically varying effects as has been assumed in conventional parametric approaches, LOSEM indicated substantial nonlinear shifts in genetic variance for several phenotypes. The operating characteristics of LOSEM were interrogated through simulation studies where the functional form of the interaction effect was known. LOSEM provides a conservative estimate of G × E interaction with sufficient power to detect statistically significant G × E signal with moderate sample size. We offer recommendations for the application of LOSEM and provide scripts for implementing these biometric models in Mplus and in OpenMx under R. PMID:26318287
De Stavola, Bianca L.; Daniel, Rhian M.; Ploubidis, George B.; Micali, Nadia
2015-01-01
The study of mediation has a long tradition in the social sciences and a relatively more recent one in epidemiology. The first school is linked to path analysis and structural equation models (SEMs), while the second is related mostly to methods developed within the potential outcomes approach to causal inference. By giving model-free definitions of direct and indirect effects and clear assumptions for their identification, the latter school has formalized notions intuitively developed in the former and has greatly increased the flexibility of the models involved. However, through its predominant focus on nonparametric identification, the causal inference approach to effect decomposition via natural effects is limited to settings that exclude intermediate confounders. Such confounders are naturally dealt with (albeit with the caveats of informality and modeling inflexibility) in the SEM framework. Therefore, it seems pertinent to revisit SEMs with intermediate confounders, armed with the formal definitions and (parametric) identification assumptions from causal inference. Here we investigate: 1) how identification assumptions affect the specification of SEMs, 2) whether the more restrictive SEM assumptions can be relaxed, and 3) whether existing sensitivity analyses can be extended to this setting. Data from the Avon Longitudinal Study of Parents and Children (1990–2005) are used for illustration. PMID:25504026
A GENERAL PANEL MODEL WITH RANDOM AND FIXED EFFECTS: A STRUCTURAL EQUATIONS APPROACH
Bollen, Kenneth A.; Brand, Jennie E.
2011-01-01
Fixed and random effects models for longitudinal data are common in sociology. Their primary advantage is that they control for time-invariant omitted variables. However, analysts face several issues when they employ these models. One is the uncertainty of whether to apply the fixed effects (FEM) versus the random effects (REM) models. Another less discussed issue is that the FEM and REM models as usually implemented might be insufficiently flexible. For instance, the effects of variables, including the latent time-invariant variable, might change over time rather than be constant as in the usual FEM and REM. The latent time-invariant variable might correlate with some variables and not others. Lagged endogenous variables might be necessary. Alternatives that move beyond the classic FEM and REM models are known, but they involve different estimators and software that make these extended models difficult to implement and to compare. This paper presents a general panel model that includes the standard FEM and REM as special cases. In addition, it provides a sequence of nested models that provide a richer range of models that researchers can easily compare with likelihood ratio tests and fit statistics. Furthermore, researchers can implement our general panel model and its special cases in widely available structural equation models (SEMs) software. The paper is oriented towards applied researchers with most technical details given in the appendix and footnotes. An extended empirical example illustrates our results. PMID:21769157
New solitary wave solutions of some nonlinear evolution equations with distinct physical structures
NASA Astrophysics Data System (ADS)
Sakthivel, Rathinasamy; Chun, Changbum
2008-12-01
In this paper, we obtain solitary wave solutions for some nonlinear partial differential equations. The Exp-function method is used to establish solitary wave solutions for Calogero-Bogoyavlenskii-Schiff and general modified Degasperis-Procesi and Camassa-Holm equations. The result shows that the Exp-function method yields new and more general solutions. Moreover, this method with the aid of symbolic computation provides a very effective and powerful mathematical tool for solving nonlinear evolution equations arising in mathematical physics.
Development of the Parental Psychological Flexibility Questionnaire.
Burke, Kylie; Moore, Susan
2015-08-01
This paper describes development and validation of the Parental Psychological Flexibility (PPF) Questionnaire, a parent-report measure designed to assess psychological flexibility among parents of pre-adolescents and adolescents (aged 10-18 years). Psychological flexibility within parenting refers to parents' accepting negative thoughts, emotions and urges about one's child and still acting in ways that are consistent with effective parenting. Exploratory factor analysis (n = 178 parents) of a 43-item draft measure, resulted in a 30-item, 3-factor structure. Three subscales were created, consistent with the psychological flexibility literature: acceptance, cognitive defusion and committed action. A second sample of parents (n = 192) was then used to confirm the factor structure and reliability and validity of the PPF. Results supported the 3-factor structure, reduced the number of items to 19 and demonstrated that the PPF subscales have adequate reliability and validity and are thus suitable for researching psychological flexibility among parents of pre-adolescents and adolescents. PMID:25236325
NASA Astrophysics Data System (ADS)
Krishnaswami, Govind S.
2006-08-01
Large-N multi-matrix loop equations are formulated as quadratic difference equations in concatenation of gluon correlations. Though non-linear, they involve highest rank correlations linearly. They are underdetermined in many cases. Additional linear equations for gluon correlations, associated to symmetries of action and measure are found. Loop equations aren't differential equations as they involve left annihilation, which doesn't satisfy the Leibnitz rule with concatenation. But left annihilation is a derivation of the commutative shuffle product. Moreover shuffle and concatenation combine to define a bialgebra. Motivated by deformation quantization, we expand concatenation around shuffle in powers of q, whose physical value is 1. At zeroth order the loop equations become quadratic PDEs in the shuffle algebra. If the variation of the action is linear in iterated commutators of left annihilations, these quadratic PDEs linearize by passage to shuffle reciprocal of correlations. Remarkably, this is true for regularized versions of the Yang-Mills, Chern-Simons and Gaussian actions. But the linear equations are underdetermined just as the loop equations were. For any particular solution, the shuffle reciprocal is explicitly inverted to get the zeroth order gluon correlations. To go beyond zeroth order, we find a Poisson bracket on the shuffle algebra and associative q-products interpolating between shuffle and concatenation. This method, and a complementary one of deforming annihilation rather than product are shown to give over and underestimates for correlations of a gaussian matrix model.
On the prolongation structures of Petrov type III vacuum spacetime equations
E. O. Ifidon
2011-09-22
The universal covering symmetry algebra of the Robinson-Trautman equations of Petrov Type III is shown to include the infinite-dimensional affine Kac-Moody algebra A_1 as a prolongation algebra. This algebra has slower growth than the contragradient algebra K_2 obtained previously for this equation.
NONLINEAR WAVE EQUATIONS ARISING IN MODELING OF SOME STRAIN-HARDENING STRUCTURES
Wei, Dongming
on a generalized Hooke's law. These equations can be used to model vibration of rods, beams, and plates made- alyzed and compared with some analytical solutions. 1 Generalized Hooke's law for Ludwick materials 1 for the material. When n = 1, equation (1) reduces to the Hooke's law for linear elastic material and the constant
The Manchester Driver Behaviour Questionnaire: a cross-cultural study.
Lajunen, Timo; Parker, Dianne; Summala, Heikki
2004-03-01
The aim of the present study was to investigate if the original factorial structure of the Manchester Driver Behaviour Questionnaire (DBQ) was replicated in Finland and The Netherlands. A postal questionnaire survey of drivers was carried out in Britain, Finland and The Netherlands. Exploratory factor analysis together with target (Procrustes) rotation and factorial agreement indexes were calculated to investigate the applicability of Finnish and Dutch versions of DBQ. Results of the factor comparisons showed that the DBQ four-factor structures found in Finland and The Netherlands were congruent but not perfect with the target structure found in Britain. Reliabilities of the scales were around the same level as in the British data. In addition to the four first-order factors, two second-order factors (deliberate violations and unintentional errors) were found in all three countries which supports the original structure by Reason et al. Issues related to cross-cultural use of traffic behaviour questionnaires are discussed. PMID:14642877
Structural equation modeling of the proximal–distal continuum of adherence drivers
McHorney, Colleen A; Zhang, Ning Jackie; Stump, Timothy; Zhao, Xiaoquan
2012-01-01
Objectives Nonadherence to prescription medications has been shown to be significantly influenced by three key medication-specific beliefs: patients’ perceived need for the prescribed medication, their concerns about the prescribed medication, and perceived medication affordability. Structural equation modeling was used to test the predictors of these three proximal determinants of medication adherence using the proximal–distal continuum of adherence drivers as the organizing conceptual framework. Methods In Spring 2008, survey participants were selected from the Harris Interactive Chronic Illness Panel, an internet-based panel of hundreds of thousands of adults with chronic disease. Respondents were eligible for the survey if they were aged 40 years and older, resided in the US, and reported having at least one of six chronic diseases: asthma, diabetes, hyperlipidemia, hypertension, osteoporosis, or other cardiovascular disease. A final sample size of 1072 was achieved. The proximal medication beliefs were measured by three multi-item scales: perceived need for medications, perceived medication concerns, and perceived medication affordability. The intermediate sociomedical beliefs and skills included four multi-item scales: perceived disease severity, knowledge about the prescribed medication, perceived immunity to side effects, and perceived value of nutraceuticals. Generic health beliefs and skills consisted of patient engagement in their care, health information-seeking tendencies, internal health locus of control, a single-item measure of self-rated health, and general mental health. Structural equation modeling was used to model proximal–distal continuum of adherence drivers. Results The average age was 58 years (range = 40–90 years), and 65% were female and 89% were white. Forty-one percent had at least a four-year college education, and just under half (45%) had an annual income of $50,000 or more. Hypertension and hyperlipidemia were each reported by about a quarter of respondents (24% and 23%, respectively). A smaller percentage of respondents had osteoporosis (17%), diabetes (15%), asthma (13%), or other cardiovascular disease (8%). Three independent variables were significantly associated with the three proximal adherence drivers: perceived disease severity, knowledge about the medication, and perceived value of nutraceuticals. Both perceived immunity to side effects and patient engagement was significantly associated with perceived need for medications and perceived medication concerns. Conclusion Testing the proximal–distal continuum of adherence drivers shed light on specific areas where adherence dialogue and enhancement should focus. Our results can help to inform the design of future adherence interventions as well as the content of patient education materials and adherence reminder letters. For long-term medication adherence, patients need to autonomously and intrinsically commit to therapy and that, in turn, is more likely to occur if they are both informed (disease and medication knowledge and rationale, disease severity, consequences of nonadherence, and side effects) and motivated (engaged in their care, perceive a need for medication, and believe the benefits outweigh the risks). PMID:23204839
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
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 (R (2) 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
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
Cai, Xiaodong; Bazerque, Juan Andrés; Giannakis, Georgios B
2013-01-01
Integrating genetic perturbations with gene expression data not only improves accuracy of regulatory network topology inference, but also enables learning of causal regulatory relations between genes. Although a number of methods have been developed to integrate both types of data, the desiderata of efficient and powerful algorithms still remains. In this paper, sparse structural equation models (SEMs) are employed to integrate both gene expression data and cis-expression quantitative trait loci (cis-eQTL), for modeling gene regulatory networks in accordance with biological evidence about genes regulating or being regulated by a small number of genes. A systematic inference method named sparsity-aware maximum likelihood (SML) is developed for SEM estimation. Using simulated directed acyclic or cyclic networks, the SML performance is compared with that of two state-of-the-art algorithms: the adaptive Lasso (AL) based scheme, and the QTL-directed dependency graph (QDG) method. Computer simulations demonstrate that the novel SML algorithm offers significantly better performance than the AL-based and QDG algorithms across all sample sizes from 100 to 1,000, in terms of detection power and false discovery rate, in all the cases tested that include acyclic or cyclic networks of 10, 30 and 300 genes. The SML method is further applied to infer a network of 39 human genes that are related to the immune function and are chosen to have a reliable eQTL per gene. The resulting network consists of 9 genes and 13 edges. Most of the edges represent interactions reasonably expected from experimental evidence, while the remaining may just indicate the emergence of new interactions. The sparse SEM and efficient SML algorithm provide an effective means of exploiting both gene expression and perturbation data to infer gene regulatory networks. An open-source computer program implementing the SML algorithm is freely available upon request. PMID:23717196
A structural equation model analysis of postfire plant diversity in California shrublands
Grace, J.B.; Keeley, J.E.
2006-01-01
This study investigates patterns of plant diversity following wildfires in fire-prone shrublands of California, seeks to understand those patterns in terms of both local and landscape factors, and considers the implications for fire management. Ninety study sites were established following extensive wildfires in 1993, and 1000-m2 plots were used to sample a variety of parameters. Data on community responses were collected for five years following fire. Structural equation modeling (SEM) was used to relate plant species richness to plant abundance, fire severity, abiotic conditions, within-plot heterogeneity, stand age, and position in the landscape. Temporal dynamics of average richness response was also modeled. Richness was highest in the first year following fire, indicating postfire enhancement of diversity. A general decline in richness over time was detected, with year-to-year variation attributable to annual variations in precipitation. Peak richness in the landscape was found where (1) plant abundance was moderately high, (2) within-plot heterogeneity was high, (3) soils were moderately low in nitrogen, high in sand content, and with high rock cover, (4) fire severity was low, and (5) stands were young prior to fire. Many of these characteristics were correlated with position in the landscape and associated conditions. We infer from the SEM results that postfire richness in this system is strongly influenced by local conditions and that these conditions are, in turn, predictably related to landscape-level conditions. For example, we observed that older stands of shrubs were characterized by more severe fires, which were associated with a low recovery of plant cover and low richness. These results may have implications for the use of prescribed fire in this system if these findings extrapolate to prescribed burns as we would expect. ?? 2006 by the Ecological Society of America.
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
Huang, Cheng; Guo, Chaoran; Yu, Shaohua; Feng, Yan; Song, Julia; Eriksen, Michael; Redmon, Pam; Koplan, Jeffrey
2013-01-01
Objective To investigate smoking prevalence and cessation services provided by male physicians in hospitals in three Chinese cities. Methods Data were collected from a survey of male physicians employed at 33 hospitals in Changsha, Qingdao and Wuxi City (n=720). Exploratory factor analysis was performed to identify latent variables, and confirmatory structural equation modelling analysis was performed to test the relationships between predictor variables and smoking in male physicians, and their provision of cessation services. Results Of the sampled male physicians, 25.7% were current smokers, and 54.0% provided cessation services by counselling (18.8%), distributing self-help materials (17.1%), and providing traditional remedies or medication (18.2%). Factors that predicted smoking included peer smoking (OR 1.14 95% CI 1.03 to 1.26) and uncommon knowledge (OR 0.94 95% CI 0.89 to 0.99), a variable measuring awareness of the association of smoking with stroke, heart attack, premature ageing and impotence in male adults as well as the role of passive smoking in heart attack. Factors that predicted whether physicians provided smoking cessation services included peer smoking (OR 0.82 95% CI 0.76 to 0.89), physicians’ own smoking (OR 0.87 95% CI 0.81 to 0.93), training in cessation (OR 1.36 95% CI 1.27 to 1.45) and access to smoking cessation resources (OR 1.69 95% CI 1.58 to 1.82). Conclusions The smoke-free policy is not strictly implemented at healthcare facilities, and smoking remains a public health problem among male physicians. A holistic approach, including a stricter implementation of the smoke-free policy, comprehensive education on the hazards of smoking, training in standard smoking-cessation techniques and provision of cessation resources, is needed to curb the smoking epidemic among male physicians and to promote smoking cessation services in China. PMID:23821489
Shieh, Grace S; Chen, Chung-Ming; Yu, Ching-Yun; Huang, Juiling; Wang, Woei-Fuh; Lo, Yi-Chen
2008-01-01
Background With the abundant information produced by microarray technology, various approaches have been proposed to infer transcriptional regulatory networks. However, few approaches have studied subtle and indirect interaction such as genetic compensation, the existence of which is widely recognized although its mechanism has yet to be clarified. Furthermore, when inferring gene networks most models include only observed variables whereas latent factors, such as proteins and mRNA degradation that are not measured by microarrays, do participate in networks in reality. Results Motivated by inferring transcriptional compensation (TC) interactions in yeast, a stepwise structural equation modeling algorithm (SSEM) is developed. In addition to observed variables, SSEM also incorporates hidden variables to capture interactions (or regulations) from latent factors. Simulated gene networks are used to determine with which of six possible model selection criteria (MSC) SSEM works best. SSEM with Bayesian information criterion (BIC) results in the highest true positive rates, the largest percentage of correctly predicted interactions from all existing interactions, and the highest true negative (non-existing interactions) rates. Next, we apply SSEM using real microarray data to infer TC interactions among (1) small groups of genes that are synthetic sick or lethal (SSL) to SGS1, and (2) a group of SSL pairs of 51 yeast genes involved in DNA synthesis and repair that are of interest. For (1), SSEM with BIC is shown to outperform three Bayesian network algorithms and a multivariate autoregressive model, checked against the results of qRT-PCR experiments. The predictions for (2) are shown to coincide with several known pathways of Sgs1 and its partners that are involved in DNA replication, recombination and repair. In addition, experimentally testable interactions of Rad27 are predicted. Conclusion SSEM is a useful tool for inferring genetic networks, and the results reinforce the possibility of predicting pathways of protein complexes via genetic interactions. PMID:18312694
Hurlimann, Anna; Hemphill, Elizabeth; McKay, Jennifer; Geursen, Gus
2008-09-01
The use of recycled water is being promoted through policy in many parts of the world with the aim of achieving sustainable water management. However there are some major barriers to the success of recycled water use policies and their instruments, in particular for potable reuse schemes. One of these barriers can be a lack of community support. Despite the critical nature of community attitudes to recycled water to the success of projects, they are often little understood. Further information is required to ensure the successful implementation of recycled water policy and to ensure sustainable management of water resources is achieved. The aim of this paper is to establish the key components of community satisfaction with recycled water. This was investigated through a case study of the Mawson Lakes population in South Australia, where recycled water is used for non-potable purposes through a dual water supply system (the 'recycled water system'). This paper reports results from a survey of 162 Mawson Lakes residents. A structural equation model (SEM) was developed and tested to explain and predict components of community satisfaction with recycled water use (for non-potable use) through the dual water supply system. Results indicate the components of satisfaction with recycled water use were an individual's positive perception of: the Water Authority's communication, trust in the Water Authority, fairness in the recycled water system's implementation, quality of the recycled water, financial value of the recycled water system, and risk associated with recycled water use (negative relationship). The results of this study have positive implications for the future management and implementation of recycled water projects in particular through dual water supply systems. The results indicate to water authorities and water policy developers guiding principles for community consultation with regards to the management of recycled water projects. PMID:17662519
Boyer, Laurent; Cermolacce, Michel; Dassa, Daniel; Fernandez, Jessica; Boucekine, Mohamed; Richieri, Raphaelle; Vaillant, Florence; Dumas, Remy; Auquier, Pascal; Lancon, Christophe
2012-01-01
Objective The aim of this study was to examine the complex relationships among neurocognition, insight and nonadherence in patients with schizophrenia. Methods Design: Cross-sectional study. Inclusion criteria: Diagnosis of schizophrenia according to the DSM-IV-TR criteria. Data collection: Neurocognition was assessed using a global approach that addressed memory, attention, and executive functions; insight was analyzed using the multidimensional ‘Scale to assess Unawareness of Mental Disorder;’ and nonadherence was measured using the multidimensional ‘Medication Adherence Rating Scale.’ Analysis: Structural equation modeling (SEM) was applied to examine the non-straightforward relationships among the following latent variables: neurocognition, ‘awareness of positive symptoms’ and ‘negative symptoms’, ‘awareness of mental disorder’ and nonadherence. Results One hundred and sixty-nine patients were enrolled. The final testing model showed good fit, with normed ?2?=?1.67, RMSEA?=?0.063, CFI?=?0.94, and SRMR?=?0.092. The SEM revealed significant associations between (1) neurocognition and ‘awareness of symptoms,’ (2) ‘awareness of symptoms’ and ‘awareness of mental disorder’ and (3) ‘awareness of mental disorder’ and nonadherence, mainly in the ‘attitude toward taking medication’ dimension. In contrast, there were no significant links between neurocognition and nonadherence, neurocognition and ‘awareness of mental disorder,’ and ‘awareness of symptoms’ and nonadherence. Conclusions Our findings support the hypothesis that neurocognition influences ‘awareness of symptoms,’ which must be integrated into a higher level of insight (i.e., the ‘awareness of mental disorder’) to have an impact on nonadherence. These findings have important implications for the development of effective strategies to enhance medication adherence. PMID:23144705
NASA Technical Reports Server (NTRS)
Hale, A. L.; Meirovitch, L.
1977-01-01
This paper outlines a computer program especially tailored to the task of deriving explicit equations of motion for structures with point-connected substructures. The special purpose program is written in FORTRAN and is designed for performing the specific algebraic operations encountered in the derivation of explicit equations of motion. The derivation is by the Lagrangian approach. Using an orderly kinematical procedure and a discretization and/or truncation scheme, it is possible to write the kinetic and potential energy of each substructure in a compact vector-matrix form. Then, if each element of the matrices and vectors encountered in the kinetic and potential energy is a known algebraic expression, the computer program performs the necessary operations to evaluate the kinetic and potential energy of the system explicitly. Lagrange's equations for small motions about equilibrium can be deduced directly from the explicit form of the system kinetic and potential energy.
Construction and Validation of Attitudes Toward Plagiarism Questionnaire
Mavrinac, Martina; Brumini, Gordana; Bili?-Zulle, Lidija; Petrove?ki, Mladen
2010-01-01
Aim To develop and test the psychometric characteristics of a questionnaire measuring attitudes toward plagiarism. Methods Participants were 227 undergraduates and graduate students from three Croatian universities, with a median age of 21 years (range 18 to 48). Research was conducted from March to June 2009. For the purpose of construction of the first version of the questionnaire, 67 statements (items) were developed. The statements were based on the relevant literature and were developed following rules and recommendations for questionnaire writing, and 36 items were chosen for final validation. Factor analysis was used to find out the factor structure of the questionnaire and to measure construct validity. Results The final version of the questionnaire consisted of 29 items divided into a three-factor structure: factor I – positive attitude toward plagiarism (12 items); factor II – negative attitude toward plagiarism (7 items); and factor III – subjective norms toward plagiarism (10 items). Cronbach ? was calculated to confirm the reliability of the scale: factor I – ??=?0.83; factor II – ??=?0.79; and factor III – ??=?0.85. Correlations between factors were: -0.37 between I and II, -0.41 between I and III, and +0.31 between II and III. Conclusion Attitudes Toward Plagiarism questionnaire was developed, with good psychometric characteristics. It will be used in future research as a standardized tool for measuring attitudes toward plagiarism. PMID:20564761
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.
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
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.
Rancourt, Diana; Jelalian, Elissa
2014-01-01
Objective?To introduce and illustrate recent advances in statistical approaches to simultaneous modeling of multiple change processes.?Methods?Provide a general overview of how to use structural equations to simultaneously model multiple change processes and illustrate the use of a theoretical model of change to guide selection of an appropriate specification from competing alternatives. The selected latent change score model is then fit to data collected during an adolescent weight-control treatment trial.?Results?A latent change score model is built starting with the foundation of repeated-measures analysis of variance and illustrated using graphical notation.?Conclusions?The assumptions behind using structural equations to model change are discussed as well as limitations of the approach. Practical guidance is provided on matching the statistical model to the theory underlying the observed change processes and the research question(s) being answered by the analyses. PMID:24190912
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.
Hiroyuki Shimada; Anne Tiedemann; Stephen R. Lord; Megumi Suzukawa; Hyuma Makizako; Kumiko Kobayashi; Takao Suzuki
2011-01-01
The purpose of this study was to determine the interrelationships between lower limb muscle performance, balance, gait and falls in older people using structural equation modeling. Study participants were two hundred and thirteen people aged 65 years and older (mean age, 80.0±7.1 years), who used day-care services in Japan. The outcome measures were the history of falls three months retrospectively
Federal Register 2010, 2011, 2012, 2013, 2014
2013-07-26
...Standards Questionnaire(s); Complaint Intake Form AGENCY: Office of Labor Relations...Labor Standards Questionnaire; Complaint Intake Form. OMB Approval Number: 2501-0018...4731, Federal Labor Standard Complaint Intake form, will be used by HUD and...
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
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
2014-01-01
Background Self-rated health is a robust predictor of several health outcomes, such as functional ability, health care utilization, morbidity and mortality. The purpose of this study is to investigate and explore how health locus of control and disease burden relate to self-rated health among patients at risk for cardiovascular disease. Methods In 2009, 414 Swedish patients who were using statins completed a questionnaire about their health, diseases and their views on the three-dimensional health locus of control scale. The scale determines which category of health locus of control – internal, chance or powerful others – a patient most identifies with. The data was analyzed using logistic regression and a structural equation modeling approach. Results The analyses showed positive associations between internal health locus of control and self-rated health, and a negative association between health locus of control in chance and powerful others and self-rated health. High internal health locus of control was negatively associated with the cumulative burden of diseases, while health locus of control in chance and powerful others were positively associated with burden of diseases. In addition, age and education level had indirect associations with self-rated health through health locus of control. Conclusions This study suggests that self-rated health is positively correlated with internal locus of control and negatively associated with high locus of control in chance and powerful others in patients at high risk for cardiovascular disease. Furthermore, disease burden seems to be negatively associated with self-rated health. PMID:24885619
Emotion Regulation Questionnaire (ERQ) Gross & John
Gross, James J.
Emotion Regulation Questionnaire (ERQ) Gross & John 9/03 The Emotion Regulation Questionnaire is designed to assess individual differences in the habitual use of two emotion regulation strategies differences in two emotion regulation processes: Implications for affect, relationships, and well
Surveys and questionnaires in nursing research.
Timmins, Fiona
2015-06-17
Surveys and questionnaires are often used in nursing research to elicit the views of large groups of people to develop the nursing knowledge base. This article provides an overview of survey and questionnaire use in nursing research, clarifies the place of the questionnaire as a data collection tool in quantitative research design and provides information and advice about best practice in the development of quantitative surveys and questionnaires. PMID:26080989
Thermodynamic structure of Lanczos-Lovelock field equations from near-horizon symmetries
Kothawala, Dawood; Padmanabhan, T.
2009-05-15
It is well known that, for a wide class of spacetimes with horizons, Einstein equations near the horizon can be written as a thermodynamic identity. It is also known that the Einstein tensor acquires a highly symmetric form near static, as well as stationary, horizons. We show that, for generic static spacetimes, this highly symmetric form of the Einstein tensor leads quite naturally and generically to the interpretation of the near-horizon field equations as a thermodynamic identity. We further extend this result to generic static spacetimes in Lanczos-Lovelock gravity, and show that the near-horizon field equations again represent a thermodynamic identity in all these models. These results confirm the conjecture that this thermodynamic perspective of gravity extends far beyond Einstein's theory.
Exact multiplicity and global structure of solutions for a class of semilinear elliptic equations
NASA Astrophysics Data System (ADS)
Xu, Benlong
2008-05-01
In this paper, we establish an exact multiplicity result of solutions for a class of semilinear elliptic equation. We also obtain a precise global bifurcation diagram of the solution set. As a result, an open problem presented by C.-H. Hsu and Y.-W. Shih [C.-H. Hsu, Y.-W. Shih, Solutions of semilinear elliptic equations with asymptotic linear nonlinearity, Nonlinear Anal. 50 (2002) 275-283] is completely solved. Our argument is mainly based on bifurcation theory and continuation method.
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…
A Brief Guide to Questionnaire Development
NSDL National Science Digital Library
Robert Frary
This comprehensive guide leads the user step-by-step through questionnaire creation. Topics include preliminary considerations, writing the questionnaire items, issues that may come up when giving the questionnaire, statistical considerations, and references for further reading. This resource is intended for novice and professional evaluators.
Murakami, S.; Mizuno, M. )
1991-08-01
This paper reports on the constitutive equations for creep, swelling, and damage under irradiation discussed in terms of incorporating the transient behavior of swelling after the incubation fluence as well as the effect of transient creep. Creep during irradiation is assumed to consist of irradiation-induced creep and irradiation-affected thermal creep, and the dilatational part of irradiation-induced creep is identified with swelling. The irradiation-induced creep is formulated by postulating the stress-induced preferential absorption mechanism. Then, the continuous transition of swelling after the incubation fluence is formulated using the curvature parameter of Bates and Korenko. For transient creep, on the other hand, the McVetty creep law and the Kachanov-Rabotnov creep damage theory are modified to describe irradiation-affected thermal creep. The resulting equations are applied to predict creep before, during, and after irradiation of 20% cold-worked Type 316 stainless steel at elevated temperatures, and the validity of the equations is discussed by comparison with experiments. Finally, the bulging and rupture process in fast breeder reactor fuel cladding is analyzed using the equations.
A steplike contrast structure in a singularly perturbed system of elliptic equations
NASA Astrophysics Data System (ADS)
Butuzov, V. F.; Levashova, N. T.; Mel'nikova, A. A.
2013-09-01
A singularly perturbed boundary value problem for a system of elliptic equations in a two-dimensional region is considered. The asymptotics and existence of a solution with an internal transition layer are studied. The asymptotics is justified by the method of differential inequalities.
NASA Astrophysics Data System (ADS)
Butuzov, V. F.; Levashova, N. T.; Mel'nikova, A. A.
2012-11-01
A singularly perturbed boundary value problem for a system of equations with different powers of a small parameter is considered in the one-dimensional case. The asymptotic behavior and existence of a solution with an internal transition layer are analyzed. The asymptotics are substantiated using the asymptotic method of differential inequalities.
The viscous Cahn-Hilliard equation: Morse decomposition and structure of the global attractor
the Ginzburg{Landau free energy functional F() = Z fF()+ 2 2 jrj2gdx and look for constrained (mass. For the Cahn{Hilliard equation one knows, moreover, that there exist inertial manifolds [36] and inertial sets [15]. By de#12;nition, the inertial manifolds and inertial sets are #12;nite dimensional
The viscous CahnHilliard equation: Morse decomposition and structure of the global attractor
functional F(j) = Z \\Omega fF (j) + ffl 2 2 jrjj 2 g dx and look for constrained (mass--conserving) gradient this is not in general the case. For the Cahn--Hilliard equation one knows, moreover, that there exist inertial manifolds [36] and inertial sets [15]. By definition, the inertial manifolds and inertial sets are finite
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.
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
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.
Waldyr A. Rodrigues Jr.; Samuel A. Wainer
2015-06-01
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,\
NASA Astrophysics Data System (ADS)
Babaji, G.; Hussain, L. A.
Solving the Poisson equation for the electrostatic potential in a solid is an integral part of a modern electronic structure calculation. In this work, the Poisson equation for the diamond-structure semiconductors is solved using the Green Function Cellular Method. The charge density was obtained from a first principle consideration of the atomic wave functions for the electrons. The real solid harmonics JL, and HL are used in expanding the Poisson equation Green function, therefore, most of the calculations were done in the spherical coordinates system. The maximum value of the index L considered is six. The Poisson equation is solved only for the state k = 0 in this work. The results show that the total electron-electron Coulomb potential, VCE(rn) is given mainly by the central cell contribution and thus varies in a similar fashion. From a certain value at the origin, the total potential initially increases with the distance up to a certain point and then decreases as the distance is further advanced. The peak potential is roughly at about 0.05d in carbon, 0.03d in silicon and germanium, and 0.02d in gray tin. The rate of convergence of the external cells potential contribution over the l summation is faster than the central cell contribution, while the total potential rate is the slowest. In general the rate of convergence at a given point depends on the distance and direction of the point. The mathematical formulation and the results of the calculations are presented and discussed
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.
Thermodynamic structure of field equations near apparent horizon for radiating black holes
Uma Papnoi; Megan Govender; Sushant G Ghosh
2014-11-10
We study the intriguing analogy between gravitational dynamics of the horizon and thermodynamics for the case of nonstationary radiating spherically symmetric black holes both in four dimensions and higher dimensions. By defining all kinematical parameters of nonstationary radiating black holes in terms of null vectors, we demonstrate that it is possible to interpret the Einstein field equations near the apparent horizon in the form of a thermodynamical identity $TdS=dE+PdV$.
Symmetry and Hamiltonian structure of the scaling equation in isotropic turbulence
Zheng Ran; Shuqin Pan
2010-07-19
The assumption of similarity and self-preservation, which permits an analytical determination of the energy decay in isotropic turbulence, has played an important role in the development of turbulence theory for more than half a century. Sedov (1944), who first found an ingenious way to obtain two equations from one. Nonethless, it appears that this problem has never been reinvestigated in depth subsequent to this earlier work. In the present paper, such an analysis is carried out, yielding a much more complete picture of self-preservation isotropic turbulence. Based on these exact solutions, some physically significant consequences of recent advances in the theory of self-preserved homogenous statistical solution of the Navier-Stokes equations are presented. New results could be obtained for the analysis on turbulence features, such as the scaling behavior, the spectrum, and also the large scale dynamics. The general energy spectra and their behavior in different wave number range are investigated. This letter only focus on the scaling equation.
The Development and Psychometric Properties of the Selective Mutism Questionnaire
ERIC Educational Resources Information Center
Bergman, R. Lindsey; Keller, Melody L.; Piacentini, John; Bergman, Andrea J.
2008-01-01
Research on selective mutism (SM) has been limited by the absence of standardized, psychometrically sound assessment measures. The purpose of our investigation was to present two studies that examined the factor structure and initial reliability and validity of the Selective Mutism Questionnaire (SMQ), a 17-item parent report measure of failure to…
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…
Latent Variable Analysis of the Rutter Children's Behavior Questionnaire.
ERIC Educational Resources Information Center
Berglund, Lars
1999-01-01
Analyzed the data from the Rutter Children's Behaviour Questionnaire (M. Rutter, 1967) from 450 Swedish children in grades 2, 5, and 8 using latent variable analysis. Findings show a structure described by a nested hierarchical model with seven first order factors. Some items have rather weak relations to their latent factors. (SLD)
The Development and Psychometric Properties of the Selective Mutism Questionnaire
R. Lindsey Bergman; Melody L. Keller; John Piacentini; Andrea J. Bergman
2008-01-01
Research on selective mutism (SM) has been limited by the absence of standardized, psychometrically sound assessment measures. The purpose of our investigation was to present two studies that examined the factor structure and initial reliability and validity of the Selective Mutism Questionnaire (SMQ), a 17-item parent report measure of failure to speak related to SM. Study 1 (N = 589) utilized an
The Development and Evaluation of the Academic Entitlement Questionnaire
ERIC Educational Resources Information Center
Kopp, Jason P.; Zinn, Tracy E.; Finney, Sara J.; Jurich, Daniel P.
2011-01-01
Validity evidence was gathered for the Academic Entitlement Questionnaire (AEQ). After reviewing entitlement literature, items were written to cover the breadth of academic entitlement. Results provide evidence for the substantive, structural, and external aspects of validity of the AEQ. Implications for research and use of the AEQ are discussed.…
Kramer, A; Assadian, O; Helfrich, J; Krüger, C; Pfenning, I; Ryll, S; Perner, A; Loczenski, B
2013-01-01
From January to May 2012, 1,860 hospitals throughout Germany received a questionnaire encompassing 77 items. Additionally, 300 outpatient care services and 310 nursing homes for elderly in Berlin also received a 10-item questionnaire asking on their implemented infection control practices. All questionnaires were anonymous. A total of 229 completed questionnaires from hospitals, 14 questionnaires from outpatient care services, and 16 questionnaires from nursing homes were eligible for further analysis. The lack of Infection Control physicians was identified as the largest issue. In hospitals sized 400-999 beds a gap of 71%, and in hospitals sized ?1,000 beds a gap of 17% was reported. Depending on the number of hospital beds, 13-29% of hospitals sized ?100 beds reported not havening one infection control nurse. Since based on the number of beds in larger institutions or in facilities caring for high-risk patients several infection control nurses may be required, the deficiency in infection control nurses may even be higher, particularly in secondary and tertiary care facilities. Furthermore, the analysis revealed that the legal requirements for surveillance and reporting of notifiable infectious diseases have not yet been implemented in 11% of the facilities. The implementation of antibiotic strategies did show significant gaps. However, deficiencies in the implemented measures for the prevention of surgical site infections were less frequent. Yet 12% of the participants did not have a dedicated infection control concept for their surgical services. Eight percent of hospitals were not prepared for an outbreak management and 10% did not have established regulations for wearing surgical scrubs. Deficiencies in waste disposal and the control of air-conditioning systems were also noted. Based on the results of this survey, conclusions on the optimal resource allocation for further improvement of patient safety may be drawn. While all participating nursing homes had some sort of infection control consultation, this only applied to 12 out of 16 outpatient nursing services. However, all 16 nursing services worked on the basis of an implemented infection control plan. Though legally binding hygiene recommendations have not yet been implemented for nursing homes, the necessity of infection control to assure patient safety has obviously been recognised throughout these services. PMID:23967397
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.
Wave packets in Honeycomb Structures and Two-Dimensional Dirac Equations
Charles L. Fefferman; Michael I. Weinstein
2012-12-25
In a recent article [10], the authors proved that the non-relativistic Schr\\"odinger operator with a generic honeycomb lattice potential has conical (Dirac) points in its dispersion surfaces. These conical points occur for quasi-momenta, which are located at the vertices of the Brillouin zone, a regular hexagon. In this paper, we study the time-evolution of wave-packets, which are spectrally concentrated near such conical points. We prove that the large, but finite, time dynamics is governed by the two-dimensional Dirac equations.
Algebraic structure of $tt^*$ equations for Calabi-Yau sigma models
Alim, Murad
2014-01-01
The $tt^*$ equations define a flat connection on the moduli spaces of $2d, \\mathcal{N}=2$ quantum field theories. For conformal theories with $c=3d$, which can be realized as nonlinear sigma models into Calabi-Yau d-folds, this flat connection is equivalent to special geometry for threefolds and to its analogs in other dimensions. We show that the non-holomorphic content of the $tt^*$ equations in the cases $d=1,2,3$ is captured in terms of finitely many generators of special functions, which close under derivatives. The generators are understood as coordinates on a larger moduli space. This space parameterizes a freedom in choosing representatives of the chiral ring while preserving a constant topological metric. Geometrically, the freedom corresponds to a choice of forms on the target space respecting the Hodge filtration and having a constant pairing. Linear combinations of vector fields on that space are identified with generators of a Lie algebra. This Lie algebra replaces the non-holomorphic derivatives...
Woesler, Richard [Florian-Geyer-Str. 96, 12489 Berlin (Germany)
2007-02-21
The computations of the present text with non-relativistic quantum teleportation equations and special relativity are totally speculative, physically correct computations can be done using quantum field theory, which remain to be done in future. Proposals for what might be called statistical time loop experiments with, e.g., photon polarization states are described when assuming the simplified non-relativistic quantum teleportation equations and special relativity. However, a closed time loop would usually not occur due to phase incompatibilities of the quantum states. Histories with such phase incompatibilities are called inconsistent ones in the present text, and it is assumed that only consistent histories would occur. This is called an exclusion principle for inconsistent histories, and it would yield that probabilities for certain measurement results change. Extended multiple parallel experiments are proposed to use this statistically for transmission of classical information over distances, and regarding time. Experiments might be testable in near future. However, first a deeper analysis, including quantum field theory, remains to be done in future.
Self-administered Clinical Questionnaire for Outpatients
Gumpel, J. M.; Mason, A. M. S.
1974-01-01
A self-administered questionnaire designed for prerecording the routine clinical information required from outpatients has been found to be acceptable to them. Such a questionnaire should greatly ease the collection and recording of basic clinical information and offer the doctor more effective use of his time. With the questionnaire more information was recorded and therefore available in the case notes than at a conventional doctor-patient consultation. No administrative problems occurred in its distribution, use, and return. PMID:4832238